Measurement of lifetimes in Fe,6462,Co,6361 , and 59Mn

NASA Astrophysics Data System (ADS)

Klintefjord, M.; Ljungvall, J.; Görgen, A.; Lenzi, S. M.; Bello Garrote, F. L.; Blazhev, A.; Clément, E.; de France, G.; Delaroche, J.-P.; Désesquelles, P.; Dewald, A.; Doherty, D. T.; Fransen, C.; Gengelbach, A.; Georgiev, G.; Girod, M.; Goasduff, A.; Gottardo, A.; Hadyńska-KlÈ©k, K.; Jacquot, B.; Konstantinopoulos, T.; Korichi, A.; Lemasson, A.; Libert, J.; Lopez-Martens, A.; Michelagnoli, C.; Navin, A.; Nyberg, J.; Pérez-Vidal, R. M.; Roccia, S.; Sahin, E.; Stefan, I.; Stuchbery, A. E.; Zielińska, M.; Barrientos, D.; Birkenbach, B.; Boston, A.; Charles, L.; Ciemala, M.; Dudouet, J.; Eberth, J.; Gadea, A.; González, V.; Harkness-Brennan, L.; Hess, H.; Jungclaus, A.; Korten, W.; Menegazzo, R.; Mengoni, D.; Million, B.; Pullia, A.; Ralet, D.; Recchia, F.; Reiter, P.; Salsac, M. D.; Sanchis, E.; Stezowski, O.; Theisen, Ch.; Valiente Dobon, J. J.

2017-02-01

Lifetimes of the 41+ states in Fe,6462 and the 11 /21- states in Co,6361 and 59Mn were measured at the Grand Accélérateur National d'Ions Lourds (GANIL) facility by using the Advanced Gamma Tracking Array (AGATA) and the large-acceptance variable mode spectrometer (VAMOS++). The states were populated through multinucleon transfer reactions with a 238U beam impinging on a 64Ni target, and lifetimes in the picosecond range were measured by using the recoil distance Doppler shift method. The data show an increase of collectivity in the iron isotopes approaching N =40 . The reduction of the subshell gap between the ν 2 p1 /2 and ν 1 g9 /2 orbitals leads to an increased population of the quasi-SU(3) pair (ν 1 g9 /2,ν 2 d5 /2 ), which causes an increase in quadrupole collectivity. This is not observed for the cobalt isotopes with N <40 for which the neutron subshell gap is larger due to the repulsive monopole component of the tensor nucleon-nucleon interaction. The extracted experimental B (E 2 ) values are compared with large-scale shell-model calculations and with beyond-mean-field calculations with the Gogny D1S interaction. A good agreement between calculations and experimental values is found, and the results demonstrate in particular the spectroscopic quality of the Lenzi, Nowacki, Poves, and Sieja (LNPS) shell-model interaction.

Experimental study of the isovector giant dipole resonance in 80Zr and 81Rb

NASA Astrophysics Data System (ADS)

Ceruti, S.; Camera, F.; Bracco, A.; Mentana, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Bocchi, G.; Bottoni, S.; Brambilla, S.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Wieland, O.; Bazzacco, D.; Ciemala, M.; Farnea, E.; Gottardo, A.; Kmiecik, M.; Maj, A.; Mengoni, D.; Michelagnoli, C.; Modamio, V.; Montanari, D.; Napoli, D.; Recchia, F.; Sahin, E.; Ur, C.; Valiente-Dobón, J. J.; Wasilewska, B.; Zieblinski, M.

2017-01-01

The isovector giant dipole resonance (IVGDR) γ decay was measured in the compound nuclei 80Zr and 81Rb at an excitation energy of E*=54 MeV. The fusion reaction 40Ca+40Ca at Ebeam=136 MeV was used to form the compound nucleus 80Zr, while the reaction 37Cl+44Ca at Ebeam=95 MeV was used to form the compound nucleus 81Rb at the same excitation energy. The IVGDR parameters extracted from the analysis were compared with the ones found at higher excitation energy (E*=83 MeV). The comparison allows one to observe two different nuclear mechanisms: (i) the IVGDR intrinsic width remains constant with the excitation energy in the nucleus 81Rb; (ii) the isospin-violating spreading width (i.e., Coulomb spreading width) remains constant with the excitation energy in the nucleus 80Zr. The experimental setup used for the γ -ray detection was composed by the AGATA demonstrator array coupled to the large-volume LaBr3:Ce detectors of the HECTOR+ array.

Gamma Ray Spectroscopy: Some highlights from the past, present and future

NASA Astrophysics Data System (ADS)

Beausang, Cornelius

2007-04-01

The early implementation stages of the current generation of large scale gamma-ray spectrometers, EUROGAM Phase 1 closely followed by Gammasphere Early Implementation, came online in the early 1990's. Last August the tenth anniversary of the full Gammasphere Array was celebrated. Large arrays of Compton suppressed Ge detectors, such as Gammasphere, Eurogam/Euroball/Jurosphere operated in both stand alone mode and, more recently, when coupled to highly selective and sensitive channel selection devices, such as the Fragment Mass Analyzer or RITU, or auxiliary detectors, such as Microball and Chico, have led to an unprecedented increase in our knowledge of the properties of the atomic nucleus when stressed by the application of high angular momentum, large proton or neutron imbalance, high temperatures etc. Gamma-ray spectroscopy is now routinely carried out at the limits of nuclear existence, either in terms of mass or in nuclei on, or beyond, the drip-lines. This talk will touch upon some of the classic results obtained with such arrays, will review the current state of the art in gamma-ray spectroscopy and consider some potentials for the future of the field with new arrays such as GRETA in the US and AGATA in Europe. This work is supported by the US Department of Energy under grant numbers DE-FG52-06NA26206 and DE-FG02-05ER41379.

Pygmy dipole resonance in 140Ce via inelastic scattering of 17O

NASA Astrophysics Data System (ADS)

Krzysiek, M.; Kmiecik, M.; Maj, A.; Bednarczyk, P.; Bracco, A.; Crespi, F. C. L.; Lanza, E. G.; Litvinova, E.; Paar, N.; Avigo, R.; Bazzacco, D.; Benzoni, G.; Birkenbach, B.; Blasi, N.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Ciemała, M.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Giaz, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hess, H.; Isocarte, R.; Jungclaus, A.; Leoni, S.; Ljungvall, J.; Lunardi, S.; Mazurek, K.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Milion, B.; Morales, A. I.; Napoli, D. R.; Nicolini, R.; Pellegri, L.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Salsac, M. D.; Siebeck, B.; Siem, S.; Söderström, P.-A.; Ur, C.; Valiente-Dobon, J. J.; Wieland, O.; Ziebliński, M.

2016-04-01

The γ decay from the high-lying states of 140Ce excited via inelastic scattering of 17O at a bombarding energy of 340 MeV was measured using the high-resolution AGATA-demonstrator array in coincidence with scattered ions detected in two segmented Δ E -E silicon detectors. Angular distributions of scattered ions and emitted γ rays were measured, as well as their differential cross sections. The excitation of 1- states below the neutron separation energy is similar to the one obtained in reactions with the α isoscalar probe. The comparison between the experimental differential cross sections and the corresponding predictions using the distorted-wave Born approximation allowed us to extract the isoscalar component of identified 1- pygmy states. For this analysis the form factor obtained by folding microscopically calculated transition densities and optical potentials was used.

Isospin Character of Low-Lying Pygmy Dipole States in Pb208 via Inelastic Scattering of O17 Ions

NASA Astrophysics Data System (ADS)

Crespi, F. C. L.; Bracco, A.; Nicolini, R.; Mengoni, D.; Pellegri, L.; Lanza, E. G.; Leoni, S.; Maj, A.; Kmiecik, M.; Avigo, R.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemała, M.; Grebosz, J.; Krzysiek, M.; Mazurek, K.; Zieblinski, M.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; Cederwall, B.; Charles, L.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Isocrate, R.; Jolie, J.; Jungclaus, A.; Karkour, N.; Korten, W.; Menegazzo, R.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Pullia, A.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Siebeck, B.; Siem, S.; Simpson, J.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.

2014-07-01

The properties of pygmy dipole states in Pb208 were investigated using the Pb208(O17, O17'γ) reaction at 340 MeV and measuring the γ decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted γ rays and of the scattered particles were measured. The results are compared with (γ, γ') and (p, p') data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2+ and 3- states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1- excited states from 4 to 8 MeV.

First measurement with a new setup for low-energy Coulomb excitation studies at INFN LNL

NASA Astrophysics Data System (ADS)

Rocchini, M.; Hadyńska-Klȩk, K.; Nannini, A.; Valiente-Dobón, J. J.; Goasduff, A.; Testov, D.; John, P. R.; Mengoni, D.; Zielińska, M.; Bazzacco, D.; Benzoni, G.; Boso, A.; Cocconi, P.; Chiari, M.; Doherty, D. T.; Galtarossa, F.; Jaworski, G.; Komorowska, M.; Matejska-Minda, M.; Melon, B.; Menegazzo, R.; Napiorkowski, P.; Napoli, D. R.; Ottanelli, M.; Perego, A.; Ramina, L.; Rampazzo, M.; Recchia, F.; Riccetto, S.; Rosso, D.; Siciliano, M.; Sona, P.

2017-07-01

A new segmented particle detector, SPIDER, has been designed to be used as an ancillary device with the GALILEO γ-ray spectrometer, as well as with other multi-detector γ-ray arrays that will be available at LNL in the future (e.g. AGATA). To commission the SPIDER-GALILEO experimental setup, a multi-step Coulomb excitation experiment was carried out with a 240 MeV beam of 66Zn produced by the Tandem-XTU accelerator at INFN Laboratori Nazionali di Legnaro. The measured particle and γ-ray spectra are compared with the results of detailed GEANT4 simulations which used the Coulomb excitation cross sections, estimated with the computer code GOSIA, as an input. The preliminary results indicate that precise transition probabilities will be obtained which are essential for solving discrepancies reported in the literature for this nucleus.

Pygmy dipole resonance in 124Sn populated by inelastic scattering of 17O

NASA Astrophysics Data System (ADS)

Pellegri, L.; Bracco, A.; Crespi, F. C. L.; Leoni, S.; Camera, F.; Lanza, E. G.; Kmiecik, M.; Maj, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Nicolini, R.; Vandone, V.; Wieland, O.; Bazzacco, D.; Bednarczyk, P.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Cederwall, B.; Charles, L.; Ciemala, M.; De Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Gernhäuser, R.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hess, H.; Isocrate, R.; Jolie, J.; Judson, D.; Jungclaus, A.; Karkour, N.; Krzysiek, M.; Litvinova, E.; Lunardi, S.; Mazurek, K.; Mengoni, D.; Michelagnoli, C.; Menegazzo, R.; Molini, P.; Napoli, D. R.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Salsac, M. D.; Siebeck, B.; Siem, S.; Simpson, J.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente Dobon, J. J.; Zieblinski, M.

2014-11-01

The γ decay from the high-lying states of 124Sn was measured using the inelastic scattering of 17O at 340 MeV. The emitted γ rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented ΔE- E silicon telescopes. The angular distribution was measured both for the γ rays and the scattered 17O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with (γ ,γ‧) and (α ,α‧ γ) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1- excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density.

Wilcoxon signed-rank-based technique for the pulse-shape analysis of HPGe detectors

NASA Astrophysics Data System (ADS)

Martín, S.; Quintana, B.; Barrientos, D.

2016-07-01

The characterization of the electric response of segmented-contact high-purity germanium detectors requires scanning systems capable of accurately associating each pulse with the position of the interaction that generated it. This process requires an algorithm sensitive to changes above the electronic noise in the pulse shapes produced at different positions, depending on the resolution of the Ge crystal. In this work, a pulse-shape comparison technique based on the Wilcoxon signed-rank test has been developed. It provides a method to distinguish pulses coming from different interaction points in the germanium crystal. Therefore, this technique is a necessary step for building a reliable pulse-shape database that can be used later for the determination of the position of interaction for γ-ray tracking spectrometry devices such as AGATA, GRETA or GERDA. The method was validated by comparison with a χ2 test using simulated and experimental pulses corresponding to a Broad Energy germanium detector (BEGe).

Laminated track design for inductrack maglev systems

DOEpatents

Post, Richard F.

2004-07-06

A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.

CMOS imager for pointing and tracking applications

NASA Technical Reports Server (NTRS)

Sun, Chao (Inventor); Pain, Bedabrata (Inventor); Yang, Guang (Inventor); Heynssens, Julie B. (Inventor)

2006-01-01

Systems and techniques to realize pointing and tracking applications with CMOS imaging devices. In general, in one implementation, the technique includes: sampling multiple rows and multiple columns of an active pixel sensor array into a memory array (e.g., an on-chip memory array), and reading out the multiple rows and multiple columns sampled in the memory array to provide image data with reduced motion artifact. Various operation modes may be provided, including TDS, CDS, CQS, a tracking mode to read out multiple windows, and/or a mode employing a sample-first-read-later readout scheme. The tracking mode can take advantage of a diagonal switch array. The diagonal switch array, the active pixel sensor array and the memory array can be integrated onto a single imager chip with a controller. This imager device can be part of a larger imaging system for both space-based applications and terrestrial applications.

Inductrack magnet configuration

DOEpatents

Post, Richard Freeman

2003-12-16

A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.

Inductrack magnet configuration

DOEpatents

Post, Richard Freeman

2003-10-14

A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.

Quadrupole collectivity in 42Ca from low-energy Coulomb excitation with AGATA

NASA Astrophysics Data System (ADS)

Hadyńska-Klęk, K.; Napiorkowski, P. J.; Zielińska, M.; Srebrny, J.; Maj, A.; Azaiez, F.; Valiente Dobón, J. J.; Kicińska-Habior, M.; Nowacki, F.; Naïdja, H.; Bounthong, B.; Rodríguez, T. R.; de Angelis, G.; Abraham, T.; Anil Kumar, G.; Bazzacco, D.; Bellato, M.; Bortolato, D.; Bednarczyk, P.; Benzoni, G.; Berti, L.; Birkenbach, B.; Bruyneel, B.; Brambilla, S.; Camera, F.; Chavas, J.; Cederwall, B.; Charles, L.; Ciemała, M.; Cocconi, P.; Coleman-Smith, P.; Colombo, A.; Corsi, A.; Crespi, F. C. L.; Cullen, D. M.; Czermak, A.; Désesquelles, P.; Doherty, D. T.; Dulny, B.; Eberth, J.; Farnea, E.; Fornal, B.; Franchoo, S.; Gadea, A.; Giaz, A.; Gottardo, A.; Grave, X.; Grębosz, J.; Görgen, A.; Gulmini, M.; Habermann, T.; Hess, H.; Isocrate, R.; Iwanicki, J.; Jaworski, G.; Judson, D. S.; Jungclaus, A.; Karkour, N.; Kmiecik, M.; Karpiński, D.; Kisieliński, M.; Kondratyev, N.; Korichi, A.; Komorowska, M.; Kowalczyk, M.; Korten, W.; Krzysiek, M.; Lehaut, G.; Leoni, S.; Ljungvall, J.; Lopez-Martens, A.; Lunardi, S.; Maron, G.; Mazurek, K.; Menegazzo, R.; Mengoni, D.; Merchán, E.; Męczyński, W.; Michelagnoli, C.; Million, B.; Myalski, S.; Napoli, D. R.; Niikura, M.; Obertelli, A.; Özmen, S. F.; Palacz, M.; Próchniak, L.; Pullia, A.; Quintana, B.; Rampazzo, G.; Recchia, F.; Redon, N.; Reiter, P.; Rosso, D.; Rusek, K.; Sahin, E.; Salsac, M.-D.; Söderström, P.-A.; Stefan, I.; Stézowski, O.; Styczeń, J.; Theisen, Ch.; Toniolo, N.; Ur, C. A.; Wadsworth, R.; Wasilewska, B.; Wiens, A.; Wood, J. L.; Wrzosek-Lipska, K.; Ziębliński, M.

2018-02-01

A Coulomb-excitation experiment to study electromagnetic properties of 42Ca was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in 42Ca were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E 2 matrix elements coupling six low-lying states in 42Ca, including the diagonal E 2 matrix elements of 21+ and 22+ states, were determined using the least-squares code gosia. The obtained set of reduced E 2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 01,2 + and 21,2 + states, as well as triaxiality for 01,2 + states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in 42Ca. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in 42Ca.

Development of a Receiver Processor For UAV Video Signal Acquisition and Tracking Using Digital Phased Array Antenna

DTIC Science & Technology

2010-09-01

53 Figure 26. Image of the phased array antenna...................................................................54...69 Figure 38. Computation of correction angle from array factor and sum/difference beams...71 Figure 39. Front panel of the tracking algorithm

The optimization of self-phased arrays for diurnal motion tracking of synchronous satellites

NASA Technical Reports Server (NTRS)

Theobold, D. M.; Hodge, D. B.

1977-01-01

The diurnal motion of a synchronous satellite necessitates mechanical tracking when a large aperture, high gain antenna is employed at the earth terminal. An alternative solution to this tracking problem is to use a self phased array consisting of a number of fixed pointed elements, each with moderate directivity. Non-mechanical tracking and adequate directive gain are achieved electronically by phase coherent summing of the element outputs. The element beamwidths provide overlapping area coverage of the satellite motion but introduce a diurnal variation into the array gain. The optimum element beamwidth and pointing direction of these elements can be obtained under the condition that the array gain is maximized simultaneously with the minimization of the diurnal variation.

Kalman filter-based tracking of moving objects using linear ultrasonic sensor array for road vehicles

NASA Astrophysics Data System (ADS)

Li, Shengbo Eben; Li, Guofa; Yu, Jiaying; Liu, Chang; Cheng, Bo; Wang, Jianqiang; Li, Keqiang

2018-01-01

Detection and tracking of objects in the side-near-field has attracted much attention for the development of advanced driver assistance systems. This paper presents a cost-effective approach to track moving objects around vehicles using linearly arrayed ultrasonic sensors. To understand the detection characteristics of a single sensor, an empirical detection model was developed considering the shapes and surface materials of various detected objects. Eight sensors were arrayed linearly to expand the detection range for further application in traffic environment recognition. Two types of tracking algorithms, including an Extended Kalman filter (EKF) and an Unscented Kalman filter (UKF), for the sensor array were designed for dynamic object tracking. The ultrasonic sensor array was designed to have two types of fire sequences: mutual firing or serial firing. The effectiveness of the designed algorithms were verified in two typical driving scenarios: passing intersections with traffic sign poles or street lights, and overtaking another vehicle. Experimental results showed that both EKF and UKF had more precise tracking position and smaller RMSE (root mean square error) than a traditional triangular positioning method. The effectiveness also encourages the application of cost-effective ultrasonic sensors in the near-field environment perception in autonomous driving systems.

Tracking and Navigation of Future NASA Spacecraft with the Square Kilometer Array

NASA Astrophysics Data System (ADS)

Resch, G. M.; Jones, D. L.; Connally, M. J.; Weinreb, S.; Preston, R. A.

2001-12-01

The international radio astronomy community is currently working on the design of an array of small radio antennas with a total collecting area of one square kilometer - more than a hundred times that of the largest existing (100-m) steerable antennas. An array of this size would provide obvious advantages for high data rate telemetry reception and for spacecraft navigation. Among these advantages are a two-orders-of-magnitude increase in sensitivity for telemetry downlink, flexible sub-arraying to track multiple spacecraft simultaneously, increased reliability through the use of large numbers of identical array elements, very accurate real-time angular spacecraft tracking, and a dramatic reduction in cost per unit area. NASA missions in many disciplines, including planetary science, would benefit from this increased ground-based tracking capability. The science return from planned missions could be increased, and opportunities for less expensive or completely new kinds of missions would be created.

Tracking marine mammals and ships with small and large-aperture hydrophone arrays

NASA Astrophysics Data System (ADS)

Gassmann, Martin

Techniques for passive acoustic tracking in all three spatial dimensions of marine mammals and ships were developed for long-term acoustic datasets recorded continuously over months using custom-designed arrays of underwater microphones (hydrophones) with spacing ranging from meters to kilometers. From the three-dimensional tracks, the acoustical properties of toothed whales and ships, such as sound intensity and directionality, were estimated as they are needed for the passive acoustic abundance estimation of toothed whales and for a quantitative description of the contribution of ships to the underwater soundscape. In addition, the tracks of the toothed whales reveal their underwater movements and demonstrate the potential of the developed tracking techniques to investigate their natural behavior and responses to sound generated by human activity, such as from ships or military SONAR. To track the periodically emitted echolocation sounds of toothed whales in an acoustically refractive environment in the upper ocean, a propagation-model based technique was developed for a hydrophone array consisting of one vertical and two L-shaped subarrays deployed from the floating instrument platform R/P FLIP. The technique is illustrated by tracking a group of five shallow-diving killer whales showing coordinated behavior. The challenge of tracking the highly directional echolocation sounds of deep-diving (< 1 km) toothed whales, in particular Cuvier's beaked whales, was addressed by embedding volumetric small-aperture (≈ 1 m element spacing) arrays into a large-aperture (≈ 1 km element spacing) seafloor array to reduce the minimum number of required receivers from five to two. The capabilities of this technique are illustrated by tracking several groups of up to three individuals over time periods from 10 min to 33 min within an area of 20 km2 in the Southern California Bight. To track and measure the underwater radiated sound of ships, a frequency domain beamformer was implemented for a volumetric hydrophone array (< 2 m element spacing) that was coupled to an autonomous acoustic seafloor recorder. This allows for the tracking and measurement of underwater radiated sound from ships of opportunity with a single instrument deployment and without depending on track information from the automatic information system (AIS).

Target Tracking Using SePDAF under Ambiguous Angles for Distributed Array Radar.

PubMed

Long, Teng; Zhang, Honggang; Zeng, Tao; Chen, Xinliang; Liu, Quanhua; Zheng, Le

2016-09-09

Distributed array radar can improve radar detection capability and measurement accuracy. However, it will suffer cyclic ambiguity in its angle estimates according to the spatial Nyquist sampling theorem since the large sparse array is undersampling. Consequently, the state estimation accuracy and track validity probability degrades when the ambiguous angles are directly used for target tracking. This paper proposes a second probability data association filter (SePDAF)-based tracking method for distributed array radar. Firstly, the target motion model and radar measurement model is built. Secondly, the fusion result of each radar's estimation is employed to the extended Kalman filter (EKF) to finish the first filtering. Thirdly, taking this result as prior knowledge, and associating with the array-processed ambiguous angles, the SePDAF is applied to accomplish the second filtering, and then achieving a high accuracy and stable trajectory with relatively low computational complexity. Moreover, the azimuth filtering accuracy will be promoted dramatically and the position filtering accuracy will also improve. Finally, simulations illustrate the effectiveness of the proposed method.

Characterization of a gamma-ray tracking array: A comparison of GRETINA and Gammasphere using a 60 Co source

DOE PAGES

Lauritsen, T.; Korichi, A.; Zhu, S.; ...

2016-08-21

In this paper, we provide a formalism for the characterization of tracking arrays with emphasis on the proper corrections required to extract their photopeak efficiencies and peak-to-total ratios. The methods are first applied to Gammasphere, a well characterized 4π array based on the principle of Compton suppression, and subsequently to GRETINA. In addition, the tracking efficiencies are then discussed and some guidelines as to what clustering angle to use in the tracking algorithm are presented. It was possible, using GEANT4 simulations, to scale the measured efficiencies up to the expected values for the full 4π implementation of GRETA.

Characterization of a gamma-ray tracking array: A comparison of GRETINA and Gammasphere using a 60 Co source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lauritsen, T.; Korichi, A.; Zhu, S.

2016-11-01

In this paper, we provide a formalism for the characterization of the tracking arrays with emphasis on the proper corrections required to extract their photopeak efficiencies and peak-to-total ratios. The methods are first applied to Gammasphere, a well characterized 4pi array based on the principle of Compton suppression, and subsequently to GRETINA. The tracking efficiencies are then discussed and some guidelines as to what clustering angle to use in the tracking algorithm are presented. It was possible, using GEANT4 simulations, to scale the measured efficiencies up to the expected values for the full 4pi implementation of GRETA.

Target Tracking Using SePDAF under Ambiguous Angles for Distributed Array Radar

PubMed Central

Long, Teng; Zhang, Honggang; Zeng, Tao; Chen, Xinliang; Liu, Quanhua; Zheng, Le

2016-01-01

Distributed array radar can improve radar detection capability and measurement accuracy. However, it will suffer cyclic ambiguity in its angle estimates according to the spatial Nyquist sampling theorem since the large sparse array is undersampling. Consequently, the state estimation accuracy and track validity probability degrades when the ambiguous angles are directly used for target tracking. This paper proposes a second probability data association filter (SePDAF)-based tracking method for distributed array radar. Firstly, the target motion model and radar measurement model is built. Secondly, the fusion result of each radar’s estimation is employed to the extended Kalman filter (EKF) to finish the first filtering. Thirdly, taking this result as prior knowledge, and associating with the array-processed ambiguous angles, the SePDAF is applied to accomplish the second filtering, and then achieving a high accuracy and stable trajectory with relatively low computational complexity. Moreover, the azimuth filtering accuracy will be promoted dramatically and the position filtering accuracy will also improve. Finally, simulations illustrate the effectiveness of the proposed method. PMID:27618058

Power optimal single-axis articulating strategies

NASA Technical Reports Server (NTRS)

Kumar, Renjith R.; Heck, Michael L.

1991-01-01

Power optimal single axis articulating PV array motion for Space Station Freedom is investigated. The motivation is to eliminate one of the articular joints to reduce Station costs. Optimal (maximum power) Beta tracking is addressed for local vertical local horizontal (LVLH) and non-LVLH attitudes. Effects of intra-array shadowing are also presented. Maximum power availability while Beta tracking is compared to full sun tracking and optimal alpha tracking. The results are quantified in orbital and yearly minimum, maximum, and average values of power availability.

Linear Combination of Heuristics Approach to Spatial Sampling Hyperspectral Data for Target Tracking

DTIC Science & Technology

2010-12-01

Figure 37 - Illustration of the tunable spectral polarimeter. ........................................... 154 Figure 38 - Illustration of micromirrors ...polarimeter. 9.2 Multiobject Tracking Spectrometer The idea of combining an array of MEMS micromirrors with an imager and a spectrometer array is the... micromirror array is located at an intermediate focal plane of the optical system. If all the individual mirrors are turned in the same direction

Feasibility Study of Solar Dome Encapsulation of Photovoltaic Arrays

NASA Technical Reports Server (NTRS)

1978-01-01

The technical and economic advantages of using air-supported plastic enclosures to protect flat plate photovoltaic arrays are described. Conceptual designs for a fixed, latitude-tilt array and a fully tracking array were defined. Detailed wind loads and strength analyses were performed for the fixed array. Detailed thermal and power output analyses provided array performance for typical seasonal and extreme temperature conditions. Costs of each design as used in a 200 MWe central power station were defined from manufacturing and material cost estimates. The capital cost and cost of energy for the enclosed fixed-tilt array were lower than for the enclosed tracking array. The enclosed fixed-tilt array capital investment was 38% less, and the levelized bus bar energy cost was 26% less than costs for a conventional, glass-encapsulated array design. The predicted energy cost for the enclosed fixed array was 79 mills/kW-h for direct current delivered to the power conditioning units.

A large-aperture low-cost hydrophone array for tracking whales from small boats.

PubMed

Miller, B; Dawson, S

2009-11-01

A passive sonar array designed for tracking diving sperm whales in three dimensions from a single small vessel is presented, and the advantages and limitations of operating this array from a 6 m boat are described. The system consists of four free floating buoys, each with a hydrophone, built-in recorder, and global positioning system receiver (GPS), and one vertical stereo hydrophone array deployed from the boat. Array recordings are post-processed onshore to obtain diving profiles of vocalizing sperm whales. Recordings are synchronized using a GPS timing pulse recorded onto each track. Sensitivity analysis based on hyperbolic localization methods is used to obtain probability distributions for the whale's three-dimensional location for vocalizations received by at least four hydrophones. These localizations are compared to those obtained via isodiachronic sequential bound estimation. Results from deployment of the system around a sperm whale in the Kaikoura Canyon in New Zealand are shown.

Quantitative 3-d diagnostic ultrasound imaging using a modified transducer array and an automated image tracking technique.

PubMed

Hossack, John A; Sumanaweera, Thilaka S; Napel, Sandy; Ha, Jun S

2002-08-01

An approach for acquiring dimensionally accurate three-dimensional (3-D) ultrasound data from multiple 2-D image planes is presented. This is based on the use of a modified linear-phased array comprising a central imaging array that acquires multiple, essentially parallel, 2-D slices as the transducer is translated over the tissue of interest. Small, perpendicularly oriented, tracking arrays are integrally mounted on each end of the imaging transducer. As the transducer is translated in an elevational direction with respect to the central imaging array, the images obtained by the tracking arrays remain largely coplanar. The motion between successive tracking images is determined using a minimum sum of absolute difference (MSAD) image matching technique with subpixel matching resolution. An initial phantom scanning-based test of a prototype 8 MHz array indicates that linear dimensional accuracy of 4.6% (2 sigma) is achievable. This result compares favorably with those obtained using an assumed average velocity [31.5% (2 sigma) accuracy] and using an approach based on measuring image-to-image decorrelation [8.4% (2 sigma) accuracy]. The prototype array and imaging system were also tested in a clinical environment, and early results suggest that the approach has the potential to enable a low cost, rapid, screening method for detecting carotid artery stenosis. The average time for performing a screening test for carotid stenosis was reduced from an average of 45 minutes using 2-D duplex Doppler to 12 minutes using the new 3-D scanning approach.

The use of integrated focal plane array technologies in laser microsatellite networks

NASA Astrophysics Data System (ADS)

Arnon, Shlomi

2004-10-01

Clustering micro satellites in cooperative fly formation constellations leads to high-performance space systems. The only way to achieve high-speed communication between the satellites is by a laser beam with a narrow divergence angle. In order to make the communication successful three types of focal plane detector arrays are required in the communication terminal: acquisition, tracking and communication detector arrays. The acquisition detector array is used to acquire the neighbor satellite using a wide field-of-view telescope. The tracking detector provides fast, real time and accurate direction location of the neighbor satellite. Based on the information from the acquisition and tracking detectors the receiver and transmitter maintain line of sight. The development of large, fast and very sensitive focal plane detector arrays makes it possible to implement the acquisition, tracking and communication with only one focal plane detector array. By doing so it is possible to reduce dramatically the size, weight, and cost of the optics and electronics which leads to lightweight communication terminals. As a result, the satellites are smaller and lighter, which reduces the space mission cost and increases the booster efficiency. In this paper we will present an overview of the concept of integrated focal plane arrays for laser satellite communication. We also present simulation results based on real system parameters and compare different implementation options.

Evaluation of Methods for In-Situ Calibration of Field-Deployable Microphone Phased Arrays

NASA Technical Reports Server (NTRS)

Humphreys, William M.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.

2017-01-01

Current field-deployable microphone phased arrays for aeroacoustic flight testing require the placement of hundreds of individual sensors over a large area. Depending on the duration of the test campaign, the microphones may be required to stay deployed at the testing site for weeks or even months. This presents a challenge in regards to tracking the response (i.e., sensitivity) of the individual sensors as a function of time in order to evaluate the health of the array. To address this challenge, two different methods for in-situ tracking of microphone responses are described. The first relies on the use of an aerial sound source attached as a payload on a hovering small Unmanned Aerial System (sUAS) vehicle. The second relies on the use of individually excited ground-based sound sources strategically placed throughout the array pattern. Testing of the two methods was performed in microphone array deployments conducted at Fort A.P. Hill in 2015 and at Edwards Air Force Base in 2016. The results indicate that the drift in individual sensor responses can be tracked reasonably well using both methods. Thus, in-situ response tracking methods are useful as a diagnostic tool for monitoring the health of a phased array during long duration deployments.

The NASA Inductrack Model Rocket Launcher at the Lawrence Livermore National Laboratory

NASA Technical Reports Server (NTRS)

Tung, L. S.; Post, R. F.; Cook, E.; Martinez-Frias, J.

2000-01-01

The Inductrack magnetic levitation system, developed at the Lawrence Livermore National Laboratory, is being studied for its possible use for launching rockets. Under NASA sponsorship, a small model system is being constructed at the Laboratory to pursue key technical aspects of this proposed application. The Inductrack is a passive magnetic levitation system employing special arrays of high-field permanent magnets (Halbach arrays) on the levitating carrier, moving above a "track" consisting of a close-packed array of shorted coils with which are interleaved with special drive coils. Halbach arrays produce a strong spatially periodic magnetic field on the front surface of the arrays, while canceling the field on their back surface. Relative motion between the Halbach arrays and the track coils induces currents in those coils. These currents levitate the carrier cart by interacting with the horizontal component of the magnetic field. Pulsed currents in the drive coils, synchronized with the motion of the carrier, interact with the vertical component of the magnetic field to provide acceleration forces. Motional stability, including resistance to both vertical and lateral aerodynamic forces, is provided by having Halbach arrays that interact with both the upper and the lower sides of the track coils. In its completed form the model system that is under construction will have a track approximately 100 meters in length along which the carrier cart will be propelled up to peak speeds of Mach 0.4 to 0.5 before being decelerated. Preliminary studies of the parameters of a full-scale system have also been made. These studies address the problems of scale-up, including means to simplify the track construction and to reduce the cost of the pulsed-power systems needed for propulsion.

Residual and suppressed-carrier arraying techniques for deep-space communications

NASA Technical Reports Server (NTRS)

Shihabi, M.; Shah, B.; Hinedi, S.; Million, S.

1995-01-01

Three techniques that use carrier information from multiple antennas to enhance carrier acquisition and tracking are presented. These techniques in combination with baseband combining are analyzed and simulated for residual and suppressed-carrier modulation. It is shown that the carrier arraying using a single carrier loop technique can acquire and track the carrier even when any single antenna in the array cannot do so by itself. The carrier aiding and carrier arraying using multiple carrier loop techniques, on the other hand, are shown to lock on the carrier only when one of the array elements has sufficient margin to acquire the carrier on its own.

Transition probabilities in neutron-rich Se,8280 and the role of the ν g9 /2 orbital

NASA Astrophysics Data System (ADS)

Litzinger, J.; Blazhev, A.; Dewald, A.; Didierjean, F.; Duchêne, G.; Fransen, C.; Lozeva, R.; Verney, D.; de Angelis, G.; Bazzacco, D.; Birkenbach, B.; Bottoni, S.; Bracco, A.; Braunroth, T.; Cederwall, B.; Corradi, L.; Crespi, F. C. L.; Désesquelles, P.; Eberth, J.; Ellinger, E.; Farnea, E.; Fioretto, E.; Gernhäuser, R.; Goasduff, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hackstein, M.; Hess, H.; Ibrahim, F.; Jolie, J.; Jungclaus, A.; Kolos, K.; Korten, W.; Leoni, S.; Lunardi, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatovic, T.; Million, B.; Möller, O.; Modamio, V.; Montagnoli, G.; Montanari, D.; Morales, A. I.; Napoli, D. R.; Niikura, M.; Pietralla, N.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Valiente-Dobón, J. J.; Vandone, V.; Vogt, A.

2018-04-01

Transition probabilities of intermediate-spin yrast and non-yrast excitations in Se,8280 were investigated in a recoil distance Doppler-shift (RDDS) experiment performed at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. The Cologne Plunger device for deep inelastic scattering was used for the RDDS technique and was combined with the AGATA Demonstrator array for the γ -ray detection and coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 80Se, the level lifetimes of the yrast (61+) and (81+) states and of a non-yrast band feeding the yrast 41+ state are determined. A spin and parity assignment of the head of this sideband is discussed based on the experimental results and supported by large-scale shell-model calculations. In 82Se, the level lifetimes of the yrast 61+ state and the yrare 42+ state and lifetime limits of the yrast (101+) state and of the 51- state are determined. Although the experimental results contain large uncertainties, they are interpreted with care in terms of large-scale shell-model calculations using the effective interactions JUN45 and jj44b. The excited states' wave functions are investigated and discussed with respect to the role of the neutron g9 /2 orbital.

Transition probabilities in neutron-rich Se,8684

NASA Astrophysics Data System (ADS)

Litzinger, J.; Blazhev, A.; Dewald, A.; Didierjean, F.; Duchêne, G.; Fransen, C.; Lozeva, R.; Sieja, K.; Verney, D.; de Angelis, G.; Bazzacco, D.; Birkenbach, B.; Bottoni, S.; Bracco, A.; Braunroth, T.; Cederwall, B.; Corradi, L.; Crespi, F. C. L.; Désesquelles, P.; Eberth, J.; Ellinger, E.; Farnea, E.; Fioretto, E.; Gernhäuser, R.; Goasduff, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hackstein, M.; Hess, H.; Ibrahim, F.; Jolie, J.; Jungclaus, A.; Kolos, K.; Korten, W.; Leoni, S.; Lunardi, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatovic, T.; Million, B.; Möller, O.; Modamio, V.; Montagnoli, G.; Montanari, D.; Morales, A. I.; Napoli, D. R.; Niikura, M.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Valiente Dobón, J. J.; Vandone, V.; Vogt, A.

2015-12-01

Reduced quadrupole transition probabilities for low-lying transitions in neutron-rich Se,8684 are investigated with a recoil distance Doppler shift (RDDS) experiment. The experiment was performed at the Istituto Nazionale di Fisica Nucleare (INFN) Laboratori Nazionali di Legnaro using the Cologne Plunger device for the RDDS technique and the AGATA Demonstrator array for the γ -ray detection coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 86Se the level lifetime of the yrast 21+ state and an upper limit for the lifetime of the 41+ state are determined for the first time. The results of 86Se are in agreement with previously reported predictions of large-scale shell-model calculations using Ni78-I and Ni78-II effective interactions. In addition, intrinsic shape parameters of lowest yrast states in 86Se are calculated. In semimagic 84Se level lifetimes of the yrast 41+ and 61+ states are determined for the first time. Large-scale shell-model calculations using effective interactions Ni78-II, JUN45, jj4b, and jj4pna are performed. The calculations describe B (E 2 ;21+→01+) and B (E 2 ;61+→41+) fairly well and point out problems in reproducing the experimental B (E 2 ;41+→21+) .

Design, testing, and economics of a 430 W sub p photovoltaic concentrator array for non grid-connected applications

NASA Astrophysics Data System (ADS)

Maish, A. B.; Rios, M., Jr.; Togami, H.

A stand-alone 430 W/sub p/ photovoltaic (PV) concentrating system for low power, non grid-connected applications has been designed, fabricated, and tested at Sandia National Laboratories. The array consists of four passively cooled Fresnel lens concentrating modules on a newly developed polar axis tracking structure. Two axis tracking is provided using a self powered clock drive unit mounted on a single post foundation. Test results of tracking accuracy, array output power, parasitic power, performance in winds and array reliability are discussed. using a range of estimated production costs for small production volumes, the life-cycle energy costs have been calculated and compared to the equivalent energy costs of a 3 kW diesel electric generator set and of an equivalent flat panel PV system.

The drift chamber array at the external target facility in HIRFL-CSR

NASA Astrophysics Data System (ADS)

Sun, Y. Z.; Sun, Z. Y.; Wang, S. T.; Duan, L. M.; Sun, Y.; Yan, D.; Tang, S. W.; Yang, H. R.; Lu, C. G.; Ma, P.; Yu, Y. H.; Zhang, X. H.; Yue, K.; Fang, F.; Su, H.

2018-06-01

A drift chamber array at the External Target Facility in HIRFL-CSR has been constructed for three-dimensional particle tracking in high-energy radioactive ion beam experiments. The design, readout, track reconstruction program and calibration procedures for the detector are described. The drift chamber array was tested in a 311 AMeV 40Ar beam experiment. The detector performance based on the measurements of the beam test is presented. A spatial resolution of 230 μm is achieved.

Deployment/retraction ground testing of a large flexible solar array

NASA Technical Reports Server (NTRS)

Chung, D. T.

1982-01-01

The simulated zero-gravity ground testing of the flexible fold-up solar array consisting of eighty-four full-size panels (.368 m x .4 m each) is addressed. Automatic, hands-off extension, retraction, and lockup operations are included. Three methods of ground testing were investigated: (1) vertical testing; (2) horizontal testing, using an overhead water trough to support the panels; and (3) horizontal testing, using an overhead track in conjunction with a counterweight system to support the panels. Method 3 was selected as baseline. The wing/assembly vertical support structure, the five-tier overhead track, and the mast-element support track comprise the test structure. The flexible solar array wing assembly was successfully extended and retracted numerous times under simulated zero-gravity conditions.

UAV Digital Tracking Array Design, Development and Testing

DTIC Science & Technology

2009-12-01

and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction...27 1. Tracking Principles ........................................................................... 27... principles and different modes for a tracking antenna. Different tracking techniques such as sequential lobing, conical scan and monopulse tracking are also

Dynamically re-configurable CMOS imagers for an active vision system

NASA Technical Reports Server (NTRS)

Yang, Guang (Inventor); Pain, Bedabrata (Inventor)

2005-01-01

A vision system is disclosed. The system includes a pixel array, at least one multi-resolution window operation circuit, and a pixel averaging circuit. The pixel array has an array of pixels configured to receive light signals from an image having at least one tracking target. The multi-resolution window operation circuits are configured to process the image. Each of the multi-resolution window operation circuits processes each tracking target within a particular multi-resolution window. The pixel averaging circuit is configured to sample and average pixels within the particular multi-resolution window.

Acoustic Source Elevation Angle Estimates Using Two Microphones

DTIC Science & Technology

2014-06-01

elevated. Elevation angles are successfully estimated, under certain conditions, for a loudspeaker broadcasting band limited white noise. 15. SUBJECT...INTENTIONALLY LEFT BLANK. 1 1. Introduction The U.S. Army uses acoustic arrays to track and locate various sources including...ground and airborne vehicles, small arms, mortars, and rockets. The tracking and locating algorithms often used with these acoustic arrays perform

Application of a single area array detector for acquistion, tracking and point-ahead in space optical communications

NASA Technical Reports Server (NTRS)

Clark, D. L.; Cosgrove, M.; Vanvranken, R.; Park, H.; Fitzmaurice, M.

1989-01-01

Functions of acquisition, tracking, and point-ahead in space optical communications are being combined into a single system utilizing an area array detector. An analysis is presented of the feasibility concept. The key parameters are: optical power less than 1 pW at 0.86 micrometer, acquisition in less than 30 seconds in an acquisition field of view (FOV) of 1 mrad, tracking with 0.5 microrad rms noise at 1000 Hz update rate, and point ahead transfer function precision of 0.25 microrad over a region of 150 microrad. Currently available array detectors were examined. The most demanding specifications are low output noise, a high detection efficiency, a large number of pixels, and frame rates over 1kHz. A proof of concept (POC) demonstration system is currently being built utilizing the Kodak HS-40 detector (a 128 x 128 photodiode array with a 64 channel CCD readout architecture which can be operated at frame rates as high as 40,000/sec). The POC system implements a windowing scheme and special purpose digital signal processing electronic for matched filter acquisition and tracking algorithms.

Array invariant-based ranging of a source of opportunity.

PubMed

Byun, Gihoon; Kim, J S; Cho, Chomgun; Song, H C; Byun, Sung-Hoon

2017-09-01

The feasibility of tracking a ship radiating random and anisotropic noise is investigated using ray-based blind deconvolution (RBD) and array invariant (AI) with a vertical array in shallow water. This work is motivated by a recent report [Byun, Verlinden, and Sabra, J. Acoust. Soc. Am. 141, 797-807 (2017)] that RBD can be applied to ships of opportunity to estimate the Green's function. Subsequently, the AI developed for robust source-range estimation in shallow water can be applied to the estimated Green's function via RBD, exploiting multipath arrivals separated in beam angle and travel time. In this letter, a combination of the RBD and AI is demonstrated to localize and track a ship of opportunity (200-900 Hz) to within a 5% standard deviation of the relative range error along a track at ranges of 1.8-3.4 km, using a 16-element, 56-m long vertical array in approximately 100-m deep shallow water.

Offshore killer whale tracking using multiple hydrophone arrays.

PubMed

Gassmann, Martin; Henderson, E Elizabeth; Wiggins, Sean M; Roch, Marie A; Hildebrand, John A

2013-11-01

To study delphinid near surface movements and behavior, two L-shaped hydrophone arrays and one vertical hydrophone line array were deployed at shallow depths (<125 m) from the floating instrument platform R/P FLIP, moored northwest of San Clemente Island in the Southern California Bight. A three-dimensional propagation-model based passive acoustic tracking method was developed and used to track a group of five offshore killer whales (Orcinus orca) using their emitted clicks. In addition, killer whale pulsed calls and high-frequency modulated (HFM) signals were localized using other standard techniques. Based on these tracks sound source levels for the killer whales were estimated. The peak to peak source levels for echolocation clicks vary between 170-205 dB re 1 μPa @ 1 m, for HFM calls between 185-193 dB re 1 μPa @ 1 m, and for pulsed calls between 146-158 dB re 1 μPa @ 1 m.

Autonomous Low Earth Orbit Satellite and Orbital Debris Tracking Using Mid Aperture COTS Optical Trackers

NASA Astrophysics Data System (ADS)

Ehrhorn, B.; Azari, D.

Low Earth Orbit (LEO) and Orbital Debris tracking have become considerably important with regard to Space Situational Awareness (SSA). This paper discusses the capabilities of autonomous LEO and Orbital Debris Tracking Systems using commercially available (mid aperture 20-24 inch) telescopes, tracking gimbals, and CCD imagers. RC Optical Systems has been developing autonomous satellite trackers that allow for unattended acquisition, imaging, and orbital determination of LEOs using low cost COTS equipment. The test setup from which we are gathering data consists of an RC Optical Systems Professional Series Elevation over Azimuth Gimbal with field de-rotation, RC Optical Systems 20 inch Ritchey-Chretien Telescope coupled to an e2v CCD42-40 CCD array, and 77mm f/4 tracking lens coupled to a KAF-0402ME CCD array. Central to success of LEO acquisition and open loop tracking is accurate modeling of Gimbal and telescope misalignments and flexures. Using pro-TPoint and a simple automated mapping routine we have modeled our primary telescope to achieve pointing and tracking accuracies within a population standard deviation of 1.3 arc-sec (which is 1.1 arc-sec RMS). Once modeled, a mobile system can easily and quickly be calibrated to the sky using a simple 6-10 star map to solve for axis tilt and collimation coefficients. Acquisition of LEO satellites is accomplished through the use of a wide field imager. Using a 77mm f/4 lens and 765 x 510 x 9mu CCD array yields a 1.28 x 0.85 degree field of view in our test setup. Accurate boresite within the acquisition array is maintained throughout the full range of motion through differential tpoint modeling of the main and acquisition imagers. Satellite identification is accomplished by detecting a stationary centroid as a point source and differentiating from the background of streaked stars in a single frame. We found 100% detection rate of LEO with radar cross sections (RCS) of > 0.5 meter*meter within the acquisition array, and approximately 90% within 0.25 degrees of center. Tests of open loop tracking revealed a vast majority of satellites remain within the main detector area of 0.19 x 0.19 degrees after initial centering. Once acquired, the satellite is centered within the main imager via automated adjustment of the epoch and inclination using non-linear least square fit. Thereafter, real time satellite position is sequentially determined and recorded using the main imaging array. Real time determination of the SGP4 Keplerian elements are solved using non-linear least squares regression. The tracking propagator is periodically updated to reflect the solved Keplerian elements in order to maintain the satellite position near image center. These processes are accomplished without the need for user intervention. Unattended fully autonomous LEO satellite tracking and orbital determination simply requires scheduling of appropriate targets and scripted command of the tracking system.

Middle-Late Pleistocene marine terraces and fault activity in the Sant'Agata di Militello coastal area (north-eastern Sicily)

NASA Astrophysics Data System (ADS)

Giunta, Giuseppe; Gueli, Anna M.; Monaco, Carmelo; Orioli, Silvia; Ristuccia, Gloria M.; Stella, Giuseppe; Troja, Sebastiano O.

2012-04-01

The coastal sector of Sant'Agata di Militello (north-eastern Sicily) is characterized by a flight of raised Middle-Upper Pleistocene marine terraces occurring at different heights with respect to present sea level. In particular, the geomorphological survey and the analysis of stereo-pairs of aerial photographs allowed to recognize at least five main orders of well preserved Quaternary surfaces and relative deposits mostly located at the hanging wall and at the footwall of the Pleistocene northwest-dipping Capo d'Orlando normal fault, which controlled the geomorphological evolution of the coastal area. The marine terraces show an overall good morphological continuity and are formed by marine platforms overlain by littoral deposits made up of yellow littoral sand and gravels in a sandy matrix. The continental sedimentary cover of the 3rd order terrace contains mammal-bearing deposits that were previously dated 200 ± 40 ka BP by isoleucine epimerization method, allowing to relate them to MIS 7.1 high-stand. In order to better define the whole terrace chronology, deposit samples were analyzed by Optically Stimulated Luminescence (OSL) methodology, a conventional SAR protocol used with sand-sized quartz. New datings, together with the detailed morphostructural analysis, allow to relate the 2nd and 4th order terraces to MIS 5.5 and 8.5, respectively, and to reconstruct the tectonic evolution of this coastal area, constraining the activity of the Capo d'Orlando fault.

High-speed particle tracking in microscopy using SPAD image sensors

NASA Astrophysics Data System (ADS)

Gyongy, Istvan; Davies, Amy; Miguelez Crespo, Allende; Green, Andrew; Dutton, Neale A. W.; Duncan, Rory R.; Rickman, Colin; Henderson, Robert K.; Dalgarno, Paul A.

2018-02-01

Single photon avalanche diodes (SPADs) are used in a wide range of applications, from fluorescence lifetime imaging microscopy (FLIM) to time-of-flight (ToF) 3D imaging. SPAD arrays are becoming increasingly established, combining the unique properties of SPADs with widefield camera configurations. Traditionally, the photosensitive area (fill factor) of SPAD arrays has been limited by the in-pixel digital electronics. However, recent designs have demonstrated that by replacing the complex digital pixel logic with simple binary pixels and external frame summation, the fill factor can be increased considerably. A significant advantage of such binary SPAD arrays is the high frame rates offered by the sensors (>100kFPS), which opens up new possibilities for capturing ultra-fast temporal dynamics in, for example, life science cellular imaging. In this work we consider the use of novel binary SPAD arrays in high-speed particle tracking in microscopy. We demonstrate the tracking of fluorescent microspheres undergoing Brownian motion, and in intra-cellular vesicle dynamics, at high frame rates. We thereby show how binary SPAD arrays can offer an important advance in live cell imaging in such fields as intercellular communication, cell trafficking and cell signaling.

An integrated bioinformatics infrastructure essential for advancing pharmacogenomics and personalized medicine in the context of the FDA's Critical Path Initiative.

PubMed

Tong, Weida; Harris, Stephen C; Fang, Hong; Shi, Leming; Perkins, Roger; Goodsaid, Federico; Frueh, Felix W

2007-01-01

Pharmacogenomics (PGx) is identified in the FDA Critical Path document as a major opportunity for advancing medical product development and personalized medicine. An integrated bioinformatics infrastructure for use in FDA data review is crucial to realize the benefits of PGx for public health. We have developed an integrated bioinformatics tool, called ArrayTrack, for managing, analyzing and interpreting genomic and other biomarker data (e.g. proteomic and metabolomic data). ArrayTrack is a highly flexible and robust software platform, which allows evolving with technological advances and changing user needs. ArrayTrack is used in the routine review of genomic data submitted to the FDA; here, three hypothetical examples of its use in the Voluntary eXploratory Data Submission (VXDS) program are illustrated.: © Published by Elsevier Ltd.

High-speed massively parallel scanning

DOEpatents

Decker, Derek E [Byron, CA

2010-07-06

A new technique for recording a series of images of a high-speed event (such as, but not limited to: ballistics, explosives, laser induced changes in materials, etc.) is presented. Such technique(s) makes use of a lenslet array to take image picture elements (pixels) and concentrate light from each pixel into a spot that is much smaller than the pixel. This array of spots illuminates a detector region (e.g., film, as one embodiment) which is scanned transverse to the light, creating tracks of exposed regions. Each track is a time history of the light intensity for a single pixel. By appropriately configuring the array of concentrated spots with respect to the scanning direction of the detection material, different tracks fit between pixels and sufficient lengths are possible which can be of interest in several high-speed imaging applications.

Performance, operational limits, of an Electronic Switching Spherical Array (ESSA) antenna

NASA Technical Reports Server (NTRS)

Stockton, R.

1979-01-01

The development of a microprocessor controller which provides multimode operational capability for the Electronic Switching Spherical Array (ESSA) Antenna is described. The best set of operating conditions were determined and the performance of an ESSA antenna was demonstrated in the following modes: (1) omni; (2) acquisition/track; (3) directive; and (4) multibeam. The control algorithms, software flow diagrams, and electronic circuitry were developed. The microprocessor and control electronics were built and interfaced with the antenna to carry out performance testing. The acquisition/track mode for users in the Tracking and Data Relay Satellite System is emphasized.

Array signal processing in the NASA Deep Space Network

NASA Technical Reports Server (NTRS)

Pham, Timothy T.; Jongeling, Andre P.

2004-01-01

In this paper, we will describe the benefits of arraying and past as well as expected future use of this application. The signal processing aspects of array system are described. Field measurements via actual tracking spacecraft are also presented.

Acoustic tracking of sperm whales in the Gulf of Alaska using a two-element vertical array and tags.

PubMed

Mathias, Delphine; Thode, Aaron M; Straley, Jan; Andrews, Russel D

2013-09-01

Between 15 and 17 August 2010, a simple two-element vertical array was deployed off the continental slope of Southeast Alaska in 1200 m water depth. The array was attached to a vertical buoy line used to mark each end of a longline fishing set, at 300 m depth, close to the sound-speed minimum of the deep-water profile. The buoy line also served as a depredation decoy, attracting seven sperm whales to the area. One animal was tagged with both a LIMPET dive depth-transmitting satellite and bioacoustic "B-probe" tag. Both tag datasets were used as an independent check of various passive acoustic schemes for tracking the whale in depth and range, which exploited the elevation angles and relative arrival times of multiple ray paths recorded on the array. Analytical tracking formulas were viable up to 2 km range, but only numerical propagation models yielded accurate locations up to at least 35 km range at Beaufort sea state 3. Neither localization approach required knowledge of the local bottom bathymetry. The tracking system was successfully used to estimate the source level of an individual sperm whale's "clicks" and "creaks" and predict the maximum detection range of the signals as a function of sea state.

A Ground-Based Near Infrared Camera Array System for UAV Auto-Landing in GPS-Denied Environment.

PubMed

Yang, Tao; Li, Guangpo; Li, Jing; Zhang, Yanning; Zhang, Xiaoqiang; Zhang, Zhuoyue; Li, Zhi

2016-08-30

This paper proposes a novel infrared camera array guidance system with capability to track and provide real time position and speed of a fixed-wing Unmanned air vehicle (UAV) during a landing process. The system mainly include three novel parts: (1) Infrared camera array and near infrared laser lamp based cooperative long range optical imaging module; (2) Large scale outdoor camera array calibration module; and (3) Laser marker detection and 3D tracking module. Extensive automatic landing experiments with fixed-wing flight demonstrate that our infrared camera array system has the unique ability to guide the UAV landing safely and accurately in real time. Moreover, the measurement and control distance of our system is more than 1000 m. The experimental results also demonstrate that our system can be used for UAV automatic accurate landing in Global Position System (GPS)-denied environments.

A linear refractive photovoltaic concentrator solar array flight experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, P.A.; Murphy, D.M.; Piszczor, M.F.

1995-12-31

Concentrator arrays deliver a number of generic benefits for space including high array efficiency, protection from space radiation effects, and minimized plasma interactions. The line focus concentrator concept delivers two added advantages: (1) low-cost mass production of the lens material and, (2) relaxation of precise array tracking requirements to only a single axis. New array designs emphasize lightweight, high stiffness, stow-ability and ease of manufacture and assembly. The linear refractive concentrator can be designed to provide an essentially flat response over a wide range of longitudinal pointing errors for satellites having only single-axis tracking capability. In this paper the authorsmore » address the current status of the SCARLET linear concentrator program with special emphasis on hardware development of an array-level linear refractive concentrator flight experiment. An aggressive, 6-month development and flight validation program, sponsored by the Ballistic Missile Defense Organization (BMDO) and NASA Lewis Research Center, will quantify and verify SCARLET benefits with in-orbit performance measurements.« less

Passive Localization of Multiple Sources Using Widely-Spaced Arrays with Application to Marine Mammals

DTIC Science & Technology

2007-09-30

the behavioral ecology of marine mammals by simultaneously tracking multiple vocalizing individuals in space and time. OBJECTIVES The ...goal is to contribute to the behavioral ecology of marine mammals by simultaneously tracking multiple vocalizing individuals in space and time. 15...OA Graduate Traineeship for E-M Nosal) LONG-TERM GOALS The goal of our research is to develop systems that use a widely spaced hydrophone array

Sensor modeling and demonstration of a multi-object spectrometer for performance-driven sensing

NASA Astrophysics Data System (ADS)

Kerekes, John P.; Presnar, Michael D.; Fourspring, Kenneth D.; Ninkov, Zoran; Pogorzala, David R.; Raisanen, Alan D.; Rice, Andrew C.; Vasquez, Juan R.; Patel, Jeffrey P.; MacIntyre, Robert T.; Brown, Scott D.

2009-05-01

A novel multi-object spectrometer (MOS) is being explored for use as an adaptive performance-driven sensor that tracks moving targets. Developed originally for astronomical applications, the instrument utilizes an array of micromirrors to reflect light to a panchromatic imaging array. When an object of interest is detected the individual micromirrors imaging the object are tilted to reflect the light to a spectrometer to collect a full spectrum. This paper will present example sensor performance from empirical data collected in laboratory experiments, as well as our approach in designing optical and radiometric models of the MOS channels and the micromirror array. Simulation of moving vehicles in a highfidelity, hyperspectral scene is used to generate a dynamic video input for the adaptive sensor. Performance-driven algorithms for feature-aided target tracking and modality selection exploit multiple electromagnetic observables to track moving vehicle targets.

Magnetic tracking for TomoTherapy systems: gradiometer based methods to filter eddy-current magnetic fields.

PubMed

McGary, John E; Xiong, Zubiao; Chen, Ji

2013-07-01

TomoTherapy systems lack real-time, tumor tracking. A possible solution is to use electromagnetic markers; however, eddy-current magnetic fields generated in response to a magnetic source can be comparable to the signal, thus degrading the localization accuracy. Therefore, the tracking system must be designed to account for the eddy fields created along the inner bore conducting surfaces. The aim of this work is to investigate localization accuracy using magnetic field gradients to determine feasibility toward TomoTherapy applications. Electromagnetic models are used to simulate magnetic fields created by a source and its simultaneous generation of eddy currents within a conducting cylinder. The source position is calculated using a least-squares fit of simulated sensor data using the dipole equation as the model equation. To account for field gradients across the sensor area (≈ 25 cm(2)), an iterative method is used to estimate the magnetic field at the sensor center. Spatial gradients are calculated with two arrays of uniaxial, paired sensors that form a gradiometer array, where the sensors are considered ideal. Experimental measurements of magnetic fields within the TomoTherapy bore are shown to be 1%-10% less than calculated with the electromagnetic model. Localization results using a 5 × 5 array of gradiometers are, in general, 2-4 times more accurate than a planar array of sensors, depending on the solenoid orientation and position. Simulation results show that the localization accuracy using a gradiometer array is within 1.3 mm over a distance of 20 cm from the array plane. In comparison, localization errors using single array are within 5 mm. The results indicate that the gradiometer method merits further studies and work due to the accuracy achieved with ideal sensors. Future studies should include realistic sensor models and extensive numerical studies to estimate the expected magnetic tracking accuracy within a TomoTherapy system before proceeding with prototype development.

Adaptive Jacobian Fuzzy Attitude Control for Flexible Spacecraft Combined Attitude and Sun Tracking System

NASA Astrophysics Data System (ADS)

Chak, Yew-Chung; Varatharajoo, Renuganth

2016-07-01

Many spacecraft attitude control systems today use reaction wheels to deliver precise torques to achieve three-axis attitude stabilization. However, irrecoverable mechanical failure of reaction wheels could potentially lead to mission interruption or total loss. The electrically-powered Solar Array Drive Assemblies (SADA) are usually installed in the pitch axis which rotate the solar arrays to track the Sun, can produce torques to compensate for the pitch-axis wheel failure. In addition, the attitude control of a flexible spacecraft poses a difficult problem. These difficulties include the strong nonlinear coupled dynamics between the rigid hub and flexible solar arrays, and the imprecisely known system parameters, such as inertia matrix, damping ratios, and flexible mode frequencies. In order to overcome these drawbacks, the adaptive Jacobian tracking fuzzy control is proposed for the combined attitude and sun-tracking control problem of a flexible spacecraft during attitude maneuvers in this work. For the adaptation of kinematic and dynamic uncertainties, the proposed scheme uses an adaptive sliding vector based on estimated attitude velocity via approximate Jacobian matrix. The unknown nonlinearities are approximated by deriving the fuzzy models with a set of linguistic If-Then rules using the idea of sector nonlinearity and local approximation in fuzzy partition spaces. The uncertain parameters of the estimated nonlinearities and the Jacobian matrix are being adjusted online by an adaptive law to realize feedback control. The attitude of the spacecraft can be directly controlled with the Jacobian feedback control when the attitude pointing trajectory is designed with respect to the spacecraft coordinate frame itself. A significant feature of this work is that the proposed adaptive Jacobian tracking scheme will result in not only the convergence of angular position and angular velocity tracking errors, but also the convergence of estimated angular velocity to the actual angular velocity. Numerical results are presented to demonstrate the effectiveness of the proposed scheme in tracking the desired attitude, as well as suppressing the elastic deflection effects of solar arrays during maneuver.

Development of a low cost integrated 15 kW A.C. solar tracking sub-array for grid connected PV power system applications

NASA Astrophysics Data System (ADS)

Stern, M.; West, R.; Fourer, G.; Whalen, W.; Van Loo, M.; Duran, G.

1997-02-01

Utility Power Group has achieved a significant reduction in the installed cost of grid-connected PV systems. The two part technical approach focused on 1) The utilization of a large area factory assembled PV panel, and 2) The integration and packaging of all sub-array power conversion and control functions within a single factory produced enclosure. Eight engineering prototype 15kW ac single axis solar tracking sub-arrays were designed, fabricated, and installed at the Sacramento Municipal Utility District's Hedge Substation site in 1996 and are being evaluated for performance and reliability. A number of design enhancements will be implemented in 1997 and demonstrated by the field deployment and operation of over twenty advanced sub-array PV power systems.

NASA Solar Array Demonstrates Commercial Potential

NASA Technical Reports Server (NTRS)

Creech, Gray

2006-01-01

A state-of-the-art solar-panel array demonstration site at NASA's Dryden Flight Research Center provides a unique opportunity for studying the latest in high-efficiency solar photovoltaic cells. This five-kilowatt solar-array site (see Figure 1) is a technology-transfer and commercialization success for NASA. Among the solar cells at this site are cells of a type that was developed in Dryden Flight Research Center s Environmental Research Aircraft and Sensor Technology (ERAST) program for use in NASA s Helios solar-powered airplane. This cell type, now denoted as A-300, has since been transferred to SunPower Corporation of Sunnyvale, California, enabling mass production of the cells for the commercial market. High efficiency separates these advanced cells from typical previously commercially available solar cells: Whereas typical previously commercially available cells are 12 to 15 percent efficient at converting sunlight to electricity, these advanced cells exhibit efficiencies approaching 23 percent. The increase in efficiency is due largely to the routing of electrical connections behind the cells (see Figure 2). This approach to increasing efficiency originated as a solution to the problem of maximizing the degree of utilization of the limited space available atop the wing of the Helios airplane. In retrospect, the solar cells in use at this site could be used on Helios, but the best cells otherwise commercially available could not be so used, because of their lower efficiencies. Historically, solar cells have been fabricated by use of methods that are common in the semiconductor industry. One of these methods includes the use of photolithography to define the rear electrical-contact features - diffusions, contact openings, and fingers. SunPower uses these methods to produce the advanced cells. To reduce fabrication costs, SunPower continues to explore new methods to define the rear electrical-contact features. The equipment at the demonstration site includes two fixed-angle solar arrays and one single-axis Sun-tracking array. One of the fixed arrays contains typical less-efficient commercial solar cells and is being used as a baseline for comparison of the other fixed array, which contains the advanced cells. The Sun-tracking array tilts to follow the Sun, using an advanced, real-time tracking device rather than customary pre-programmed mechanisms. Part of the purpose served by the demonstration is to enable determination of any potential advantage of a tracking array over a fixed array. The arrays are monitored remotely on a computer that displays pertinent information regarding the functioning of the arrays.

Detection of pointing errors with CMOS-based camera in intersatellite optical communications

NASA Astrophysics Data System (ADS)

Yu, Si-yuan; Ma, Jing; Tan, Li-ying

2005-01-01

For very high data rates, intersatellite optical communications hold a potential performance edge over microwave communications. Acquisition and Tracking problem is critical because of the narrow transmit beam. A single array detector in some systems performs both spatial acquisition and tracking functions to detect pointing errors, so both wide field of view and high update rate is required. The past systems tend to employ CCD-based camera with complex readout arrangements, but the additional complexity reduces the applicability of the array based tracking concept. With the development of CMOS array, CMOS-based cameras can employ the single array detector concept. The area of interest feature of the CMOS-based camera allows a PAT system to specify portion of the array. The maximum allowed frame rate increases as the size of the area of interest decreases under certain conditions. A commercially available CMOS camera with 105 fps @ 640×480 is employed in our PAT simulation system, in which only part pixels are used in fact. Beams angle varying in the field of view can be detected after getting across a Cassegrain telescope and an optical focus system. Spot pixel values (8 bits per pixel) reading out from CMOS are transmitted to a DSP subsystem via IEEE 1394 bus, and pointing errors can be computed by the centroid equation. It was shown in test that: (1) 500 fps @ 100×100 is available in acquisition when the field of view is 1mrad; (2)3k fps @ 10×10 is available in tracking when the field of view is 0.1mrad.

Gamma ray energy tracking in GRETINA

NASA Astrophysics Data System (ADS)

Lee, I. Y.

2011-10-01

The next generation of stable and exotic beam accelerators will provide physics opportunities to study nuclei farther away from the line of stability. However, these experiments will be more demanding on instrumentation performance. These come from the lower production rate for more exotic beams, worse beam impurities, and large beam velocity from the fragmentation and inverse reactions. Gamma-ray spectroscopy will be one of the most effective tools to study exotic nuclei. However, to fully exploit the physics reach provided by these new facilities, better gamma-ray detector will be needed. In the last 10 years, a new concept, gamma-ray energy tracking array, was developed. Tracking arrays will increase the detection sensitivity by factors of several hundred compared to current arrays used in nuclear physics research. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to correct the Doppler broadening of gamma rays emitted from high velocity nuclei. GRETINA is a gamma-ray tracking array which uses 28 Ge crystals, each with 36 segments, to cover ¼ of the 4 π of the 4 π solid angle. The gamma ray tracking technique requires detailed pulse shape information from each of the segments. These pulses are digitized using 14-bit 100 MHz flash ADCs, and digital signal analysis algorithms implemented in the on-board FPGAs provides energy, time and selection of pulse traces. A digital trigger system, provided flexible trigger functions including a fast trigger output, and also allows complicated trigger decisions to be made up to 20 microseconds. Further analyzed, carried out in a computer cluster, determine the energy, time, and three-dimensional positions of all gamma-ray interactions in the array. This information is then utilized, together with the characteristics of Compton scattering and pair-production processes, to track the scattering sequences of the gamma rays. GRETINA construction is completed in March 2011, and extensive engineering runs were carried out using radioactive sources, and beams from the 88-Inch Cyclotron at LBNL. The data obtained will be used to optimize its performance. Then the first scientific campaign will start in March 2012 at NSCL MSU.

Quantitative analysis of the improvement in omnidirectional maritime surveillance and tracking due to real-time image enhancement

NASA Astrophysics Data System (ADS)

de Villiers, Jason P.; Bachoo, Asheer K.; Nicolls, Fred C.; le Roux, Francois P. J.

2011-05-01

Tracking targets in a panoramic image is in many senses the inverse problem of tracking targets with a narrow field of view camera on a pan-tilt pedestal. In a narrow field of view camera tracking a moving target, the object is constant and the background is changing. A panoramic camera is able to model the entire scene, or background, and those areas it cannot model well are the potential targets and typically subtended far fewer pixels in the panoramic view compared to the narrow field of view. The outputs of an outward staring array of calibrated machine vision cameras are stitched into a single omnidirectional panorama and used to observe False Bay near Simon's Town, South Africa. A ground truth data-set was created by geo-aligning the camera array and placing a differential global position system receiver on a small target boat thus allowing its position in the array's field of view to be determined. Common tracking techniques including level-sets, Kalman filters and particle filters were implemented to run on the central processing unit of the tracking computer. Image enhancement techniques including multi-scale tone mapping, interpolated local histogram equalisation and several sharpening techniques were implemented on the graphics processing unit. An objective measurement of each tracking algorithm's robustness in the presence of sea-glint, low contrast visibility and sea clutter - such as white caps is performed on the raw recorded video data. These results are then compared to those obtained with the enhanced video data.

An update on the development of a line-focus refractive concentrator array

NASA Technical Reports Server (NTRS)

Piszczor, Michael F.; Oneill, Mark J.; Fraas, Lewis M.

1994-01-01

Concentrator arrays offer a number of generic benefits for space (i.e. high array efficiency, protection from space radiation effects, minimized plasma interactions, etc.). The line-focus refractive concept, however, also offers two very important advantages: (1) relaxation of precise array tracking requirements to only a single axis and (2) low-cost mass production of the lens material. The linear refractive concentrator can be designed to provide an essentially flat response over a wide range of longitudinal errors for satellites having only single-axis tracking capability. New panel designs emphasize light weight, high stiffness, storability, and ease of manufacturing and assembly. This paper addresses the current status of the concentrator program with special emphasis on the design implications, and flexibility, of using a linear refractive concentrator lens as well as details recent fabrication of prototype hardware.

An Update on the Development of a Line-Focus Refractive Concentrator Array

NASA Technical Reports Server (NTRS)

Piszczor, Michael F.; ONeill, Mark J.; Fraas, Lewis M.

1994-01-01

Concentrator arrays offer a number of generic benefits for space (i.e. high array efficiency, protection from space radiation effects, minimized plasma interactions, etc.). The line-focus refractive concentrator concept, however, also offers two very important advantages: (1) relaxation of precise array tracking requirements to only a single axis and (2) low-cost mass production of the lens material. The linear refractive concentrator can be designed to provide an essentially flat response over a wide range of longitudinal errors for satellites having only single-axis tracking capability. New panel designs emphasize light weight, high stiffness, stowability and ease of manufacturing and assembly. This paper will address the current status of the concentrator program with special emphasis on the design implications, and flexibility, of using a linear refractive concentrator lens as well as detail the recent fabrication of prototype hardware.

A compact presentation of DSN array telemetry performance

NASA Technical Reports Server (NTRS)

Greenhall, C. A.

1982-01-01

The telemetry performance of an arrayed receiver system, including radio losses, is often given by a family of curves giving bit error rate vs bit SNR, with tracking loop SNR at one receiver held constant along each curve. This study shows how to process this information into a more compact, useful format in which the minimal total signal power and optimal carrier suppression, for a given fixed bit error rate, are plotted vs data rate. Examples for baseband-only combining are given. When appropriate dimensionless variables are used for plotting, receiver arrays with different numbers of antennas and different threshold tracking loop bandwidths look much alike, and a universal curve for optimal carrier suppression emerges.

Laser radar range and detection performance for MEMS corner cube retroreflector arrays

NASA Astrophysics Data System (ADS)

Grasso, Robert J.; Odhner, Jefferson E.; Stewart, Hamilton; McDaniel, Robert V.

2004-12-01

BAE SYSTEMS reports on a program to characterize the performance of MEMS corner cube retroreflector arrays under laser illumination. These arrays have significant military and commercial application in the areas of: 1) target identification; 2) target tracking; 3) target location; 4) identification friend-or-foe (IFF); 5) parcel tracking, and; 6) search and rescue assistance. BAE SYSTEMS has theoretically determined the feasibility of these devices to learn if sufficient signal-to-noise performance exists to permit a cooperative laser radar sensor to be considered for device location and interrogation. Results indicate that modest power-apertures are required to achieve SNR performance consistent with high probability of detection and low false alarm rates.

Laser radar range and detection performance for MEMS corner cube retroreflector arrays

NASA Astrophysics Data System (ADS)

Grasso, Robert J.; Jost, Steven R.; Smith, M. J.; McDaniel, Robert V.

2004-01-01

BAE SYSTEMS reports on a program to characterize the performance of MEMS corner cube retroreflector arrays under laser illumination. These arrays have significant military and commercial application in the areas of: (1) target identification; (2) target tracking; (3) target location; (4) identification friend-or-foe (IFF); (5) parcel tracking, and; (6) search and rescue assistance. BAE SYSTEMS has theoretically determined the feasibility of these devices to learn if sufficient signal-to-noise performance exists to permit a cooperative laser radar sensor to be considered for device location and interrogation. Results indicate that modest power-apertures are required to achieve SNR performance consistent with high probability of detection and low false alarm rates.

Electronic Switching Spherical Array (ESSA) antenna systems

NASA Technical Reports Server (NTRS)

Hockensmith, R. P.

1984-01-01

ESSA (Electronic Switching Spherical Array) is an antenna system conceived, developed and qualified for linking satellite data transmissions with NASA's tracking and data relay satellites (TDRSS) and tracking and data acquisition satellites (TDAS). ESSA functions in the S band frequency region, cover 2 pi or more steradians with directional gain and operates in multiple selectable modes. ESSA operates in concert with the NASA's TDRS standard transponder in the retrodirective mode or independently in directional beam, program track and special modes. Organizations and projects to the ESSA applications for NASA's space use are introduced. Coverage gain, weight power and implementation and other performance information for satisfying a wide range of data rate requirements are included.

Lasercom system architecture with reduced complexity

NASA Technical Reports Server (NTRS)

Lesh, James R. (Inventor); Chen, Chien-Chung (Inventor); Ansari, Homayoon (Inventor)

1994-01-01

Spatial acquisition and precision beam pointing functions are critical to spaceborne laser communication systems. In the present invention, a single high bandwidth CCD detector is used to perform both spatial acquisition and tracking functions. Compared to previous lasercom hardware design, the array tracking concept offers reduced system complexity by reducing the number of optical elements in the design. Specifically, the design requires only one detector and one beam steering mechanism. It also provides the means to optically close the point-ahead control loop. The technology required for high bandwidth array tracking was examined and shown to be consistent with current state of the art. The single detector design can lead to a significantly reduced system complexity and a lower system cost.

LaserCom System Architecture With Reduced Complexity

NASA Technical Reports Server (NTRS)

Lesh, James R. (Inventor); Chen, Chien-Chung (Inventor); Ansari, Homa-Yoon (Inventor)

1996-01-01

Spatial acquisition and precision beam pointing functions are critical to spaceborne laser communication systems. In the present invention a single high bandwidth CCD detector is used to perform both spatial acquisition and tracking functions. Compared to previous lasercom hardware design, the array tracking concept offers reduced system complexity by reducing the number of optical elements in the design. Specifically, the design requires only one detector and one beam steering mechanism. It also provides means to optically close the point-ahead control loop. The technology required for high bandwidth array tracking was examined and shown to be consistent with current state of the art. The single detector design can lead to a significantly reduced system complexity and a lower system cost.

Tracking fin whale calls offshore the Galicia Margin, North East Atlantic Ocean.

PubMed

Gaspà Rebull, Oriol; Díaz Cusí, Jordi; Ruiz Fernández, Mario; Gallart Muset, Josep

2006-10-01

Data recorded during a temporary deployment of ocean bottom seismometers (OBSs) are used in this study to monitor the presence of fin whales around the array. In the summer of 2003, ten OBSs were placed 250 km from the NW coast of Iberia in the Galicia Margin, NE Atlantic Ocean for a period of one month. The recorded data set provided a large variety of signals, including fin whale vocalizations identified by their specific acoustic signature. The use of a dense array of seafloor receivers allowed investigation into the locations and tracks of the signal-generating whales using a seismological hypocentral location code. Individual pulses of different sequences have been chosen to study such tracks. Problems related to the correct identification of pulses, discrimination between direct and multiple arrivals, and the presence of more than one individual have been considered prior to location. Fin calls were concentrated in the last two weeks of the deployment and the locations were spread around the area covered by the array. These results illustrate that, besides its classical seismological aim, deployment of semipermanent seafloor seismic arrays can also provide valuable data for marine mammal behavior studies.

The Astronomical Low-Frequency Array

NASA Technical Reports Server (NTRS)

Jones, D. L.; Allen, R. J.; Blume, W. H.; Desch, M. M.; Erickson, W. C.; Kaiser, M. L.; Kassim, N. E.; Kuiper, T. B. H.; Mahoney, M. J.; Marsh, K. A.;

A Large Array of Small Antennas to Support Future NASA Missions

NASA Astrophysics Data System (ADS)

Jones, D. L.; Weinreb, S.; Preston, R. A.

2001-01-01

A team of engineers and scientists at JPL is currently working on the design of an array of small radio antennas with a total collecting area up to twenty times that of the largest existing (70 m) DSN antennas. An array of this size would provide obvious advantages for high data rate telemetry reception and for spacecraft navigation. Among these advantages are an order-of-magnitude increase in sensitivity for telemetry downlink, flexible sub-arraying to track multiple spacecraft simultaneously, increased reliability through the use of large numbers of identical array elements, very accurate real-time angular spacecraft tracking, and a dramatic reduction in cost per unit area. NASA missions in many disciplines, including planetary science, would benefit from this increased DSN capability. The science return from planned missions could be increased, and opportunities for less expensive or completely new kinds of missions would be created. The DSN array would also bean immensely valuable instrument for radio astronomy. Indeed, it would be by far the most sensitive radio telescope in the world. Additional information is contained in the original extended abstract.

Airborne electronically steerable phased array. [steerable antennas - systems analysis

NASA Technical Reports Server (NTRS)

Coats, R.

1975-01-01

Results of a study directed to the design of a lightweight high-gain, spaceborne communications array are presented. The array includes simultaneous transmission and receiving, automatic acquisition and tracking of a signal within a 60-degree cone from the array normal, and provides for independent forming of the transmit and receive beams. Application for this array is the space shuttle, space station, or any of the advanced manned (or unmanned) orbital vehicles. Performance specifications are also given.

Design, fabrication, and delivery of a charge injection device as a stellar tracking device

NASA Technical Reports Server (NTRS)

Burke, H. K.; Michon, G. J.; Tomlinson, H. W.; Vogelsong, T. L.; Grafinger, A.; Wilson, R.

1979-01-01

Six 128 x 128 CID imagers fabricated on bulk silicon and with thin polysilicon upper-level electrodes were tested in a star tracking mode. Noise and spectral response were measured as a function of temperature over the range of +25 C to -40 C. Noise at 0 C and below was less than 40 rms carriers/pixel for all devices at an effective noise bandwidth of 150 Hz. Quantum yield for all devices averaged 40% from 0.4 to 1.0 microns with no measurable temperature dependence. Extrapolating from these performance parameters to those of a large (400 x 400) array and accounting for design and processing improvements, indicates that the larger array would show a further improvement in noise performance -- on the order of 25 carriers. A preliminary evaluation of the projected performance of the 400 x 400 array and a representative set of star sensor requirements indicates that the CID has excellent potential as a stellar tracking device.

SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rea, A; Kuruvilla, A; Gill, G

Purpose: The purpose of this study was to observe the effect of an electromagnetic array used for patient localization and tumor tracking on optically-stimulated luminescent in-vivo dosimetry. Methods: A linear accelerator equipped with four photon energies was used to irradiate optically stimulated luminescent dosimeters (OSLDs) at the respective dmax depths and in the buildup region, with and without the presence of an electromagnetic array used for tumor tracking and patient localization. The OSLDs were placed on solid water slabs under 5 mm bolus and on each face of an octagonal phantom, and irradiated using both static beam and arc geometry,more » with and without the electromagnetic array under our setup. The electromagnetic array was placed 6 cm above the phantom to coincide with similar distances used during patient treatment. Ionization chamber measurements in a water phantom were also taken initially for comparison with the simple geometry OSLD measurements and published data. Results: Under simple geometry, a negligible change was observed at dmax for all energies when the electromagnetic array was placed over the setup. When measuring at five millimeter depth, increases of 1.3/3.1/16/18% were observed for energies 4X/6X/10X/15X respectively when the electromagnetic array was in place. Measurements using the octagonal phantom yielded scattered results for the lateral and posterior oblique fields, and showed increases in dose to the OSLDs placed on the anterior and lateral anterior faces of the phantom. Conclusion: Placing the electromagnetic array very close to the patient’s surface acts as a beam spoiler in the buildup region (at 5 mm depth), which in turn causes an increase in the measured dose reading of the OSLD. This increase in dose is more pronounced when the OSLD is placed directly underneath the electromagnetic array than off to one side or the other.« less

Labeled RFS-Based Track-Before-Detect for Multiple Maneuvering Targets in the Infrared Focal Plane Array.

PubMed

Li, Miao; Li, Jun; Zhou, Yiyu

2015-12-08

The problem of jointly detecting and tracking multiple targets from the raw observations of an infrared focal plane array is a challenging task, especially for the case with uncertain target dynamics. In this paper a multi-model labeled multi-Bernoulli (MM-LMB) track-before-detect method is proposed within the labeled random finite sets (RFS) framework. The proposed track-before-detect method consists of two parts-MM-LMB filter and MM-LMB smoother. For the MM-LMB filter, original LMB filter is applied to track-before-detect based on target and measurement models, and is integrated with the interacting multiple models (IMM) approach to accommodate the uncertainty of target dynamics. For the MM-LMB smoother, taking advantage of the track labels and posterior model transition probability, the single-model single-target smoother is extended to a multi-model multi-target smoother. A Sequential Monte Carlo approach is also presented to implement the proposed method. Simulation results show the proposed method can effectively achieve tracking continuity for multiple maneuvering targets. In addition, compared with the forward filtering alone, our method is more robust due to its combination of forward filtering and backward smoothing.

Labeled RFS-Based Track-Before-Detect for Multiple Maneuvering Targets in the Infrared Focal Plane Array

PubMed Central

Li, Miao; Li, Jun; Zhou, Yiyu

2015-01-01

The problem of jointly detecting and tracking multiple targets from the raw observations of an infrared focal plane array is a challenging task, especially for the case with uncertain target dynamics. In this paper a multi-model labeled multi-Bernoulli (MM-LMB) track-before-detect method is proposed within the labeled random finite sets (RFS) framework. The proposed track-before-detect method consists of two parts—MM-LMB filter and MM-LMB smoother. For the MM-LMB filter, original LMB filter is applied to track-before-detect based on target and measurement models, and is integrated with the interacting multiple models (IMM) approach to accommodate the uncertainty of target dynamics. For the MM-LMB smoother, taking advantage of the track labels and posterior model transition probability, the single-model single-target smoother is extended to a multi-model multi-target smoother. A Sequential Monte Carlo approach is also presented to implement the proposed method. Simulation results show the proposed method can effectively achieve tracking continuity for multiple maneuvering targets. In addition, compared with the forward filtering alone, our method is more robust due to its combination of forward filtering and backward smoothing. PMID:26670234

Compact, semi-passive beam steering prism array for solar concentrators.

PubMed

Zheng, Cheng; Li, Qiyuan; Rosengarten, Gary; Hawkes, Evatt; Taylor, Robert A

2017-05-10

In order to maximize solar energy utilization in a limited space (e.g., rooftops), solar collectors should track the sun. As an alternative to rotational tracking systems, this paper presents a compact, semi-passive beam steering prism array which has been designed, analyzed, and tested for solar applications. The proposed prism array enables a linear concentrator system to remain stationary so that it can integrate with a variety of different solar concentrators, and which should be particularly useful for systems which require a low profile (namely rooftop-mounted systems). A case study of this prism array working within a specific rooftop solar collector demonstrates that it can boost the average daily optical efficiency of the collector by 32.7% and expand its effective working time from 6 h to 7.33 h. Overall, the proposed design provides an alternative way to "follow" the sun for a wide range of solar thermal and photovoltaic concentrator systems.

Demonstration of Lasercom and Spatial Tracking with a Silicon Geiger-Mode APD Array

DTIC Science & Technology

2016-02-26

standardized pixel mask as described in the previous paragraph disabling 167 of the 1024 detectors in the array , this gives an absolute maximum rate...number of elements in an array based detector .5 In this paper, we present the results of photon-counting communication tests based on an arrayed ...semiconductor photon-counting detector .6 The array also has the ability to sense the spatial distribution of the received light giving it the potential to act

Spatial feature tracking impedence sensor using multiple electric fields

DOEpatents

Novak, J.L.

1998-08-11

Linear and other features on a workpiece are tracked by measuring the fields generated between electrodes arrayed in pairs. One electrode in each pair operates as a transmitter and the other as a receiver, and both electrodes in a pair are arrayed on a carrier. By combining and subtracting fields between electrodes in one pair and between a transmitting electrode in one pair and a receiving electrode in another pair, information describing the location and orientation of the sensor relative to the workpiece in up to six degrees of freedom may be obtained. Typical applications will measure capacitance, but other impedance components may be measured as well. The sensor is designed to track a linear feature axis or a protrusion or pocket in a workpiece. Seams and ridges can be tracked by this non-contact sensor. The sensor output is useful for robotic applications. 10 figs.

Spatial feature tracking impedence sensor using multiple electric fields

DOEpatents

Novak, James L.

1998-01-01

Linear and other features on a workpiece are tracked by measuring the fields generated between electrodes arrayed in pairs. One electrode in each pair operates as a transmitter and the other as a receiver, and both electrodes in a pair are arrayed on a carrier. By combining and subtracting fields between electrodes in one pair and between a transmitting electrode in one pair and a receiving electrode in another pair, information describing the location and orientation of the sensor relative to the workpiece in up to six degrees of freedom may be obtained. Typical applications will measure capacitance, but other impedance components may be measured as well. The sensor is designed to track a linear feature axis or a protrusion or pocket in a workpiece. Seams and ridges can be tracked by this non-contact sensor. The sensor output is useful for robotic applications.

Field emitter arrays and displays produced by ion tracking lithography

NASA Astrophysics Data System (ADS)

Felter, T. E.; Musket, R. G.; Bernhardt, A. F.

2005-12-01

When ions of sufficient electronic energy loss traverse a dielectric film or foil, they alter the chemical bonding along their nominally straight path within the material. A suitable etchant can quickly dissolve these so-called latent tracks leaving holes of small diameter (∼10 nm) but long length - several microns. Continuing the etching process gradually increases the diameter reproducibly and uniformly. The trackable medium can be applied as a uniform film onto large substrates. The small, monodisperse holes produced by this track etching can be used in conjunction with additional thin film processing to create functional structures attached to the substrate. For example, Lawrence Livermore National Laboratory and Candescent Technologies Corporation (CTC) co-developed a process to make arrays of gated field emitters (∼100 nm diameter electron guns) for CTC's Thin CRTTM displays, which have been fabricated to diagonal dimensions >13 in. Additional technological applications of ion tracking lithography will be briefly covered.

On the Limits of Infants' Quantification of Small Object Arrays

ERIC Educational Resources Information Center

Feigenson, Lisa; Carey, Susan

2005-01-01

Recent work suggests that infants rely on mechanisms of object-based attention and short-term memory to represent small numbers of objects. Such work shows that infants discriminate arrays containing 1, 2, or 3 objects, but fail with arrays greater than 3 [Feigenson, L., & Carey, S. (2003). Tracking individuals via object-files: Evidence from…

Fiber-optic hydrophone array for acoustic surveillance in the littoral

NASA Astrophysics Data System (ADS)

Hill, David; Nash, Phillip

2005-05-01

We describe a fibre-optic hydrophone array system architecture that can be tailored to meet the underwater acoustic surveillance requirements of the military, counter terrorist and customs authorities in protecting ports and harbours, offshore production facilities or coastal approaches. Physically the fibre-optic hydrophone array is in the form of a lightweight cable, enabling rapid deployment from a small vessel. Based upon an optical architecture of time and wavelength multiplexed interferometric hydrophones, the array is comprised of a series of hydrophone sub-arrays. Using multiple sub-arrays, extended perimeters many tens of kilometres in length can be monitored. Interrogated via a long (~50km) optical fibre data link, the acoustic date is processed using the latest open architecture sonar processing platform, ensuring that acoustic targets below, on and above the surface are detected, tracked and classified. Results obtained from an at sea trial of a 96-channel hydrophone array are given, showing the passive detection and tracking of a diver, small surface craft and big ocean going ships beyond the horizon. Furthermore, we describe how the OptaMarine fibre-optic hydrophone array fits into an integrated multi-layered approach to port and harbour security consisting of active sonar for diver detection and hull imaging, as well as thermal imaging and CCTV for surface monitoring. Finally, we briefly describe a complimentary land perimeter intruder detection system consisting of an array of fibre optic accelerometers.

The tip/tilt tracking sensor based on multi-anode photo-multiplier tube

NASA Astrophysics Data System (ADS)

Ma, Xiao-yu; Rao, Chang-hui; Tian, Yu; Wei, Kai

2013-09-01

Based on the demands of high sensitivity, precision and frame rate of tip/tilt tracking sensors in acquisition, tracking and pointing (ATP) systems for satellite-ground optical communications, this paper proposes to employ the multiple-anode photo-multiplier tubes (MAPMTs) in tip/tilt tracking sensors. Meanwhile, an array-type photon-counting system was designed to meet the requirements of the tip/tilt tracking sensors. The experiment results show that the tip/tilt tracking sensors based on MAPMTs can achieve photon sensitivity and high frame rate as well as low noise.

Laser technology for high precision satellite tracking

NASA Technical Reports Server (NTRS)

Plotkin, H. H.

1974-01-01

Fixed and mobile laser ranging stations have been developed to track satellites equipped with retro-reflector arrays. These have operated consistently at data rates of once per second with range precision better than 50 cm, using Q-switched ruby lasers with pulse durations of 20 to 40 nanoseconds. Improvements are being incorporated to improve the precision to 10 cm, and to permit ranging to more distant satellites. These include improved reflector array designs, processing and analysis of the received reflection pulses, and use of sub-nanosecond pulse duration lasers.

Field Programmable Gate Array Control of Power Systems in Graduate Student Laboratories

DTIC Science & Technology

2008-03-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited FIELD PROGRAMMABLE...REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Field Programmable Gate Array Control of Power Systems in Graduate Student...Electronics curriculum track is the development of a design center that explores Field Programmable Gate Array (FPGA) control of power electronics

Evaluation of the 2013 Southeast Asian Haze on Solar Generation Performance

PubMed Central

Maghami, Mohammadreza; Hizam, Hashim; Gomes, Chandima; Hajighorbani, Shahrooz; Rezaei, Nima

2015-01-01

Pollution in Southeast Asia is a major public energy problem and the cause of energy losses. A significant problem with respect to this type of pollution is that it decreases energy yield. In this study, two types of photovoltaic (PV) solar arrays were used to evaluate the effect of air pollution. The performance of two types of solar arrays were analysed in this research, namely, two units of a 1 kWp tracking flat photovoltaic (TFP) and two units of a 1 kWp fixed flat photovoltaic arrays (FFP). Data analysis was conducted on 2,190 samples at 30 min intervals from 01st June 2013, when both arrays were washed, until 30th June 2013. The performance was evaluated by using environmental data (irradiation, temperature, dust thickness, and air pollution index), power output, and energy yield. Multiple regression models were predicted in view of the environmental data and PV array output. Results showed that the fixed flat system was more affected by air pollution than the tracking flat plate. The contribution of this work is that it considers two types of photovoltaic arrays under the Southeast Asian pollution 2013. PMID:26275303

Light coupling into the Whispering Gallery Modes of a fiber array thin film solar cell for fixed partial Sun tracking

PubMed Central

Mariano, Marina; Rodríguez, Francisco J.; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

2014-01-01

We propose the use of whispering gallery mode coupling in a novel configuration based on implementing a thin film cell on the backside of an array of parallel fibers. We performed numerical calculations using the parameters of a thin film organic cell which demonstrate that light coupling becomes more effective as the angle for the incident light relative to the fiber array normal increases up to an optimal angle close to 55 deg. At this angle the power conversion efficiency of the fiber array solar cell we propose becomes 30% times larger than the one from an equivalent planar cell configuration. We demonstrate that the micro fiber array solar cell we propose may perform an effective partial tracking of the sun movement for over 100 degrees without any mechanical help. In addition, in the event that such fiber array cell would be installed with the adequate orientation on a vertical façade, an optimal photon-to-charge conversion would be reached for sunlight incident at 55 deg with respect to the horizon line, very close to the yearly average position for the sun at Latitude of 40 deg.

Analysis of Multi-Antenna GNSS Receiver Performance under Jamming Attacks.

PubMed

Vagle, Niranjana; Broumandan, Ali; Lachapelle, Gérard

2016-11-17

Although antenna array-based Global Navigation Satellite System (GNSS) receivers can be used to mitigate both narrowband and wideband electronic interference sources, measurement distortions induced by array processing methods are not suitable for high precision applications. The measurement distortions have an adverse effect on the carrier phase ambiguity resolution, affecting the navigation solution. Depending on the array attitude information availability and calibration parameters, different spatial processing methods can be implemented although they distort carrier phase measurements in some cases. This paper provides a detailed investigation of the effect of different array processing techniques on array-based GNSS receiver measurements and navigation performance. The main novelty of the paper is to provide a thorough analysis of array-based GNSS receivers employing different beamforming techniques from tracking to navigation solution. Two beamforming techniques, namely Power Minimization (PM) and Minimum Power Distortionless Response (MPDR), are being investigated. In the tracking domain, the carrier Doppler, Phase Lock Indicator (PLI), and Carrier-to-Noise Ratio (C/N₀) are analyzed. Pseudorange and carrier phase measurement distortions and carrier phase position performance are also evaluated. Performance analyses results from simulated GNSS signals and field tests are provided.

Experimental Validation of Displacement Underestimation in ARFI Ultrasound

PubMed Central

Czernuszewicz, Tomasz J.; Streeter, Jason E.; Dayton, Paul A.; Gallippi, Caterina M.

2014-01-01

Acoustic radiation force impulse (ARFI) imaging is an elastography technique that uses ultrasonic pulses to both displace and track tissue motion. Previous modeling studies have shown that ARFI displacements are susceptible to underestimation due to lateral and elevational shearing that occurs within the tracking resolution cell. In this study, optical tracking was utilized to experimentally measure the displacement underestimation achieved by acoustic tracking using a clinical ultrasound system. Three optically translucent phantoms of varying stiffness were created, embedded with sub-wavelength diameter microspheres, and ARFI excitation pulses with F/1.5 or F/3 lateral focal configurations were transmitted from a standard linear array to induce phantom motion. Displacements were tracked using confocal optical and acoustic methods. As predicted by earlier FEM studies, significant acoustic displacement underestimation was observed for both excitation focal configurations; the maximum underestimation error was 35% of the optically measured displacement for the F/1.5 excitation pulse in the softest phantom. Using higher F/#, less tightly focused beams in the lateral dimension improved accuracy of displacements by approximately 10 percentage points. This work experimentally demonstrates limitations of ARFI implemented on a clinical scanner using a standard linear array and sets up a framework for future displacement tracking validation studies. PMID:23858054

Solar array maximum power tracking with closed-loop control of a 30-centimeter ion thruster

NASA Technical Reports Server (NTRS)

Gruber, R. P.

1977-01-01

A new solar array/ion thruster system control concept has been developed and demonstrated. An ion thruster beam load is used to automatically and continuously operate an unregulated solar array at its maximum power point independent of variations in solar array voltage and current. Preliminary tests were run which verified that this method of control can be implemented with a few, physically small, signal level components dissipating less than two watts.

A 18 m 2 cylindrical tracking detector made of 2.6 m long, stereo mylar straw tubes with 100 μm resolution

NASA Astrophysics Data System (ADS)

Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Ghezzo, A.; Guaraldo, C.; Lanaro, A.; Locchi, P.; Lu, J.; Lucherini, V.; Mecozzi, A.; Pace, E.; Passamonti, L.; Qaisar, N.; Ricciardi, A.; Sarwar, S.; Serdyouk, V.; Trasatti, L.; Volkov, A.; Zia, A.

1998-12-01

An array of 2424 2.6 m-long, 15 mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled. The array covers a cylindrical tracking surface of 18 m 2 and provides coordinate measurement in the drift direction and along the wire. A correction of the systematic effects which are introduced by gravitational sag and electrostatics, thus dominating the detector performance especially with long straws, allows to determine wire position from drift-time distribution. The correction has been applied to reach a space resolution of 40 μm with DME, 100 μm with Ar+C 2H 6, and 100-200 μm with CO 2. Such a resolution is the best ever obtained for straws of these dimensions. A study of the gas leakage for the straw system has been performed, and results are reported. The array is being commissioned as a subdetector of the FINUDA spectrometer, and tracking performances are being studied with cosmic rays.

Power collection reduction by mirror surface nonflatness and tracking error for a central receiver solar power system.

PubMed

McFee, R H

1975-07-01

The effects of random waviness, curvature, and tracking error of plane-mirror heliostats in a rectangular array around a central-receiver solar power system are determined by subdividing each mirror into 484 elements, assuming the slope of each element to be representative of the surface slope average at its location, and summing the contributions of all elements and then of all mirrors in the array. Total received power and flux density distribution are computed for a given sun location and set of array parameter values. Effects of shading and blocking by adjacent mirrors are included in the calculation. Alt-azimuth mounting of the heliostats is assumed. Representative curves for two receiver diameters and two sun locations indicate a power loss of 20% for random waviness, curvature, and tracking error of 0.1 degrees rms, 0.002 m(-1), and 0.5 degrees , 3sigma, respectively, for an 18.2-m diam receiver and 0.3 degrees rms, 0.005 m(-1), and greater than 1 degrees , respectively, for a 30.4-m diam receiver.

Adaptive Locally Optimum Processing for Interference Suppression from Communication and Undersea Surveillance Signals

DTIC Science & Technology

1994-07-01

1993. "Analysis of the 1730-1732. Track - Before - Detect Approach to Target Detection using Pixel Statistics", to appear in IEEE Transactions Scholz, J...large surveillance arrays. One approach to combining energy in different spatial cells is track - before - detect . References to examples appear in the next... track - before - detect problem. The results obtained are not expected to depend strongly on model details. In particular, the structure of the tracking

Two microstrip arrays for interferometric SAR applications

NASA Technical Reports Server (NTRS)

Huang, J.

1993-01-01

Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

Automatic detection of recoil-proton tracks and background rejection criteria in liquid scintillator-micro-capillary-array fast neutron spectrometer

NASA Astrophysics Data System (ADS)

Mor, Ilan; Vartsky, David; Dangendorf, Volker; Tittelmeier, Kai.; Weierganz, Mathias; Goldberg, Mark Benjamin; Bar, Doron; Brandis, Michal

2018-06-01

We describe an analysis procedure for automatic unambiguous detection of fast-neutron-induced recoil proton tracks in a micro-capillary array filled with organic liquid scintillator. The detector is viewed by an intensified CCD camera. This imaging neutron detector possesses the capability to perform high position-resolution (few tens of μm), energy-dispersive transmission-imaging using ns-pulsed beams. However, when operated with CW or DC beams, it also features medium-quality spectroscopic capabilities for incident neutrons in the energy range 2-20 MeV. In addition to the recoil proton events which display a continuous extended track structure, the raw images exhibit complex ion-tracks from nuclear interactions of fast-neutrons in the scintillator, capillaries quartz-matrix and CCD. Moreover, as expected, one also observes a multitude of isolated scintillation spots of varying intensity (henceforth denoted "blobs") that originate from several different sources, such as: fragmented proton tracks, gamma-rays, heavy-ion reactions as well as events and noise that occur in the image-intensifier and CCD. In order to identify the continuous-track recoil proton events and distinguish them from all these background events, a rapid, computerized and automatic track-recognition-procedure was developed. Based on an appropriately weighted analysis of track parameters such as: length, width, area and overall light intensity, the method is capable of distinguishing a single continuous-track recoil proton from typically surrounding several thousands of background events that are found in each CCD frame.

Lightweight Battery Charge Regulator Used to Track Solar Array Peak Power

NASA Technical Reports Server (NTRS)

Soeder, James F.; Button, Robert M.

1999-01-01

A battery charge regulator based on the series-connected boost regulator (SCBR) technology has been developed for high-voltage spacecraft applications. The SCBR regulates the solar array power during insolation to prevent battery overcharge or undercharge conditions. It can also be used to provide regulated battery output voltage to spacecraft loads if necessary. This technology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. The high-voltage SCBR shown in the photograph has demonstrated power densities of over 1000 watts per kilogram (W/kg). Using four 150-W dc-dc converter modules, it can process 2500 W of power at 120 Vdc with a minimum input voltage of 90 Vdc. Efficiency of the SCBR was 94 to 98 percent over the entire operational range. Internally, the unit is made of two separate SCBR s, each with its own analog control circuitry, to demonstrate the modularity of the technology. The analog controllers regulate the output current and incorporate the output voltage limit with active current sharing between the two units. They also include voltage and current telemetry, on/off control, and baseplate temperature sensors. For peak power tracking, the SCBR was connected to a LabView-based data acquisition system for telemetry and control. A digital control algorithm for tracking the peak power point of a solar array was developed using the principle of matching the source impedance with the load impedance for maximum energy transfer. The algorithm was successfully demonstrated in a simulated spacecraft electrical system at the Boeing PhantomWorks High Voltage Test Facility in Seattle, Washington. The system consists of a 42-string, high-voltage solar array simulator, a 77-cell, 80-ampere-hour (A-hr) nickel-hydrogen battery, and a constant power-load module. The SCBR and the LabView control algorithm successfully tracked the solar array peak power point through various load transients, including sunlight discharge transients when the total load exceeded the maximum solar array output power.

Superdeformed and Triaxial States in 42Ca

NASA Astrophysics Data System (ADS)

Hadyńska-KlÈ©k, K.; Napiorkowski, P. J.; Zielińska, M.; Srebrny, J.; Maj, A.; Azaiez, F.; Valiente Dobón, J. J.; Kicińska-Habior, M.; Nowacki, F.; Naïdja, H.; Bounthong, B.; Rodríguez, T. R.; de Angelis, G.; Abraham, T.; Anil Kumar, G.; Bazzacco, D.; Bellato, M.; Bortolato, D.; Bednarczyk, P.; Benzoni, G.; Berti, L.; Birkenbach, B.; Bruyneel, B.; Brambilla, S.; Camera, F.; Chavas, J.; Cederwall, B.; Charles, L.; Ciemała, M.; Cocconi, P.; Coleman-Smith, P.; Colombo, A.; Corsi, A.; Crespi, F. C. L.; Cullen, D. M.; Czermak, A.; Désesquelles, P.; Doherty, D. T.; Dulny, B.; Eberth, J.; Farnea, E.; Fornal, B.; Franchoo, S.; Gadea, A.; Giaz, A.; Gottardo, A.; Grave, X.; GrÈ©bosz, J.; Görgen, A.; Gulmini, M.; Habermann, T.; Hess, H.; Isocrate, R.; Iwanicki, J.; Jaworski, G.; Judson, D. S.; Jungclaus, A.; Karkour, N.; Kmiecik, M.; Karpiński, D.; Kisieliński, M.; Kondratyev, N.; Korichi, A.; Komorowska, M.; Kowalczyk, M.; Korten, W.; Krzysiek, M.; Lehaut, G.; Leoni, S.; Ljungvall, J.; Lopez-Martens, A.; Lunardi, S.; Maron, G.; Mazurek, K.; Menegazzo, R.; Mengoni, D.; Merchán, E.; MÈ©czyński, W.; Michelagnoli, C.; Mierzejewski, J.; Million, B.; Myalski, S.; Napoli, D. R.; Nicolini, R.; Niikura, M.; Obertelli, A.; Özmen, S. F.; Palacz, M.; Próchniak, L.; Pullia, A.; Quintana, B.; Rampazzo, G.; Recchia, F.; Redon, N.; Reiter, P.; Rosso, D.; Rusek, K.; Sahin, E.; Salsac, M.-D.; Söderström, P.-A.; Stefan, I.; Stézowski, O.; Styczeń, J.; Theisen, Ch.; Toniolo, N.; Ur, C. A.; Vandone, V.; Wadsworth, R.; Wasilewska, B.; Wiens, A.; Wood, J. L.; Wrzosek-Lipska, K.; ZiÈ©bliński, M.

2016-08-01

Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in 42Ca were determined from E 2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 02+ has been obtained and the role of triaxiality in the A ˜40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time.

Design analysis tracking and data relay satellite simulation system

NASA Technical Reports Server (NTRS)

1974-01-01

The design and development of the equipment necessary to simulate the S-band multiple access link between user spacecraft, the Tracking and Data Relay Satellite, and a ground control terminal are discussed. The core of the S-band multiple access concept is the use of an Adaptive Ground Implemented Phased Array. The array contains thirty channels and provides the multiplexing and demultiplexing equipment required to demonstrate the ground implemented beam forming feature. The system provided will make it possible to demonstrate the performance of a desired user and ten interfering sources attempting to pass data through the multiple access system.

Energy conversion system

DOEpatents

Murphy, Lawrence M.

1987-01-01

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.

Energy conversion system

DOEpatents

Murphy, L.M.

1985-09-16

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.

Application of a silicon photodiode array for solar edge tracking in the Halogen Occultation Experiment

NASA Technical Reports Server (NTRS)

Mauldin, L. E., III; Moore, A. S.; Stump, C. S.; Mayo, L. S.

1985-01-01

The optical and electronic design of the Halogen Occultation Experiment (HALOE) elevation sunsensor is described. This system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned, monolithic charge coupled device. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the HALOE science instantaneous-field-of-view (IFOV) across the vertical solar diameter during instrument calibration, and then maintain the science IFOV four arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 0.7 micrometer operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability. The HALOE instrument is a gas correlation radiometer that is now being developed by NASA Langley Research Center for the Upper Atmospheric Research Satellite.

Faraday rotation measurement method and apparatus

NASA Technical Reports Server (NTRS)

Brockman, M. H. (Inventor)

1981-01-01

A method and device for measuring Faraday rotation of a received RF signal is described. A simultaneous orthogonal polarization receiver compensates for a 3 db loss due to splitting of a received signal into left circular and right circular polarization channels. The compensation is achieved by RF and modulation arraying utilizing a specific receiver array which also detects and measures Faraday rotation in the presence or absence of spin stabilization effects on a linear polarization vector. Either up-link or down-link measurement of Faraday rotation is possible. Specifically, the Faraday measurement apparatus utilized in conjunction with the specific receiver array provides a means for comparing the phase of a reference signal in the receiver array to the phase of a tracking loop signal related to the incoming signal, and comparing the phase of the reference signal to the phase of the tracking signal shifted in phase by 90 degrees. The averaged and unaveraged signals, are compared, the phase changes between the two signals being related to Faraday rotation.

Near- Source, Seismo-Acoustic Signals Accompanying a NASCAR Race at the Texas Motor Speedway

NASA Astrophysics Data System (ADS)

Stump, B. W.; Hayward, C.; Underwood, R.; Howard, J. E.; MacPhail, M. D.; Golden, P.; Endress, A.

2014-12-01

Near-source, seismo-acoustic observations provide a unique opportunity to characterize urban sources, remotely sense human activities including vehicular traffic and monitor large engineering structures. Energy separately coupled into the solid earth and atmosphere provides constraints on not only the location of these sources but also the physics of the generating process. Conditions and distances at which these observations can be made are dependent upon not only local geological conditions but also atmospheric conditions at the time of the observations. In order to address this range of topics, an empirical, seismo-acoustic study was undertaken in and around the Texas Motor Speedway in the Dallas-Ft. Worth area during the first week of April 2014 at which time a range of activities associated with a series of NASCAR races occurred. Nine, seismic sensors were deployed around the 1.5-mile track for purposes of documenting the direct-coupled seismic energy from the passage of the cars and other vehicles on the track. Six infrasound sensors were deployed on a rooftop in a rectangular array configuration designed to provide high frequency beam forming for acoustic signals. Finally, a five-element infrasound array was deployed outside the track in order to characterize how the signals propagate away from the sources in the near-source region. Signals recovered from within the track were able to track and characterize the motion of a variety of vehicles during the race weekend including individual racecars. Seismic data sampled at 1000 sps documented strong Doppler effects as the cars approached and moved away from individual sensors. There were faint seismic signals that arrived at seismic velocity but local acoustic to seismic coupling as supported by the acoustic observations generated the majority of seismic signals. Actual seismic ground motions were small as demonstrated by the dominance of regional seismic signals from a magnitude 4.0 earthquake that arrived at the local seismometers as the race began. The infrasound arrays recorded a variety of atmosphere only processes including substantial helicopter traffic although the array outside the track did not capture the details of the race as a result of the rapid attenuation of high frequency signals.

Improvements to Passive Acoustic Tracking Methods for Marine Mammal Monitoring

DTIC Science & Technology

2016-05-02

separate and associate calls from individual animals . Marine mammal; Passive acoustic monitoring; Localization; Tracking; Multiple source; Sparse array...position and hydrophone timing offset in addition to animal position Almost all marine mammal tracking methods treat animal position as the only unknown...Workshop on Detection, Classification and Localization (DCL) of Marine Mammals). The animals were expected to be relatively close to the surface

Array-based infra-red detection: an enabling technology for people counting, sensing, tracking, and intelligent detection

NASA Astrophysics Data System (ADS)

Stogdale, Nick; Hollock, Steve; Johnson, Neil; Sumpter, Neil

2003-09-01

A 16x16 element un-cooled pyroelectric detector array has been developed which, when allied with advanced tracking and detection algorithms, has created a universal detector with multiple applications. Low-cost manufacturing techniques are used to fabricate a hybrid detector, intended for economic use in commercial markets. The detector has found extensive application in accurate people counting, detection, tracking, secure area protection, directional sensing and area violation; topics which are all pertinent to the provision of Homeland Security. The detection and tracking algorithms have, when allied with interpolation techniques, allowed a performance much higher than might be expected from a 16x16 array. This paper reviews the technology, with particular attention to the array structure, algorithms and interpolation techniques and outlines its application in a number of challenging market areas. Viewed from above, moving people are seen as 'hot blobs' moving through the field of view of the detector; background clutter or stationary objects are not seen and the detector works irrespective of lighting or environmental conditions. Advanced algorithms detect the people and extract size, shape, direction and velocity vectors allowing the number of people to be detected and their trajectories of motion to be tracked. Provision of virtual lines in the scene allows bi-directional counting of people flowing in and out of an entrance or area. Definition of a virtual closed area in the scene allows counting of the presence of stationary people within a defined area. Definition of 'counting lines' allows the counting of people, the ability to augment access control devices by confirming a 'one swipe one entry' judgement and analysis of the flow and destination of moving people. For example, passing the 'wrong way' up a denied passageway can be detected. Counting stationary people within a 'defined area' allows the behaviour and size of groups of stationary people to be analysed and counted, an alarm condition can also be generated when people stray into such areas.

Solar photovoltaic power stations

NASA Technical Reports Server (NTRS)

Chowaniec, C. R.; Pittman, P. F.; Ferber, R. R.; Marshall, B. W.

1977-01-01

The subsystems of a solar photovoltaic central power system are identified and the cost of major components are estimated. The central power system, which would have a peak power capability in the range of 50 to 1000 MW, utilizes two types of subsystems - a power conditioner and a solar array. Despite differences in costs of inverters, the overall cost of the total power conditioning subsystem is about the same for all approaches considered. A combination of two inverters operating from balanced dc buses as a pair of 6-pulse groups is recommended. A number of different solar cell modules and tracking array structures were analyzed. It is concluded that when solar cell costs are high (greater than $500/kW), high concentration modules are more cost effective than those with low concentration. Vertical-axis tracking is the most effective of the studied tracking modes. For less expensive solar cells (less than $400/kW), fixed tilt collector/reflector modules are more cost effective than those which track.

Imaging with New Classic and Vision at the NPOI

NASA Astrophysics Data System (ADS)

Jorgensen, Anders

2018-04-01

The Navy Precision Optical Interferometer (NPOI) is unique among interferometric observatories for its ability to position telescopes in an equally-spaced array configuration. This configuration is optimal for interferometric imaging because it allows the use of bootstrapping to track fringes on long baselines with signal-to-noise ratio less than one. When combined with coherent integration techniques this can produce visibilities with acceptable SNR on baselines long enough to resolve features on the surfaces of stars. The stellar surface imaging project at NPOI combines the bootstrapping array configuration of the NPOI array, real-time fringe tracking, baseline- and wavelength bootstrapping with Earth rotation to provide dense coverage in the UV plane at a wide range of spatial frequencies. In this presentation, we provide an overview of the project and an update of the latest status and results from the project.

Real-Time Atmospheric Phase Fluctuation Correction Using a Phased Array of Widely Separated Antennas: X-Band Results and Ka-Band Progress

NASA Astrophysics Data System (ADS)

Geldzahler, B.; Birr, R.; Brown, R.; Grant, K.; Hoblitzell, R.; Miller, M.; Woods, G.; Argueta, A.; Ciminera, M.; Cornish, T.; D'Addario, L.; Davarian, F.; Kocz, J.; Lee, D.; Morabito, D.; Tsao, P.; Jakeman-Flores, H.; Ott, M.; Soloff, J.; Denn, G.; Church, K.; Deffenbaugh, P.

2016-09-01

NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Kaband) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida. In addition, we have used up to three 34m antennas separated by 250m at the Goldstone Deep Space Communication Complex in California at X-band 7.1 GHz incorporating real-time correction for tropospheric phase fluctuations. Such a demonstration can enable NASA to design and establish a high power, high resolution, 24/7 availability radar system for (a) tracking and characterizing observations of Near Earth Objects (NEOs), (b) tracking, characterizing and determining the statistics of small-scale (≤10cm) orbital debris, (c) incorporating the capability into its space communication and navigation tracking stations for emergency spacecraft commanding in the Ka band era which NASA is entering, and (d) fielding capabilities of interest to other US government agencies. We present herein the results of our phased array uplink combining at near 7.17 and 8.3 GHz using widely separated antennas demonstrations at both locales, the results of a study to upgrade from a communication to a radar system, and our vision for going forward in implementing a high performance, low lifecycle cost multi-element radar array.

Three-dimensional tracking of Cuvier's beaked whales' echolocation sounds using nested hydrophone arrays.

PubMed

Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

2015-10-01

Cuvier's beaked whales (Ziphius cavirostris) were tracked using two volumetric small-aperture (∼1 m element spacing) hydrophone arrays, embedded into a large-aperture (∼1 km element spacing) seafloor hydrophone array of five nodes. This array design can reduce the minimum number of nodes that are needed to record the arrival of a strongly directional echolocation sound from 5 to 2, while providing enough time-differences of arrivals for a three-dimensional localization without depending on any additional information such as multipath arrivals. To illustrate the capabilities of this technique, six encounters of up to three Cuvier's beaked whales were tracked over a two-month recording period within an area of 20 km(2) in the Southern California Bight. Encounter periods ranged from 11 min to 33 min. Cuvier's beaked whales were found to reduce the time interval between echolocation clicks while alternating between two inter-click-interval regimes during their descent towards the seafloor. Maximum peak-to-peak source levels of 179 and 224 dB re 1 μPa @ 1 m were estimated for buzz sounds and on-axis echolocation clicks (directivity index = 30 dB), respectively. Source energy spectra of the on-axis clicks show significant frequency components between 70 and 90 kHz, in addition to their typically noted FM upsweep at 40-60 kHz.

Infrared Imagery of Shuttle (IRIS). Task 2, summary report

NASA Technical Reports Server (NTRS)

Chocol, C. J.

1978-01-01

End-to-end tests of a 16 element indium antimonide sensor array and 10 channels of associated electronic signal processing were completed. Quantitative data were gathered on system responsivity, frequency response, noise, stray capacitance effects, and sensor paralleling. These tests verify that the temperature accuracies, predicted in the Task 1 study, can be obtained with a very carefully designed electro-optical flight system. Pre-flight and inflight calibration of a high quality are mandatory to obtain these accuracies. Also, optical crosstalk in the array-dewar assembly must be carefully eliminated by its design. Tests of the scaled up tracking system reticle also demonstrate that the predicted tracking system accuracies can be met in the flight system. In addition, improvements in the reticle pattern and electronics are possible, which will reduce the complexity of the flight system and increase tracking accuracy.

Technical Objective Document. Fiscal Year 1989

DTIC Science & Technology

1987-12-01

other special interest areas/technologies; and throuch a " delphi " process with the Center Technical Investment Committee *develop a "puts and takes...radar and larce optical systems in space, the detection and trackina of low observables, and the operation of sensors for tracking objects in space for...for reducing the processing time for adaptive beamforming in receive arrays, self-coherina techniques in larce distributed arrays and array self

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butler, W; Merrick, G; Kurko, B

Purpose: To quantify the effect of metal hip prosthesis on the ability to track and localize electromagnetic transponders. Methods: Three Calypso transponders were implanted into two prostate phantoms. The geometric center of the transponders were identified on computed tomography and set as the isocenter. With the phantom stationary on the treatment table and the tracking array 14-cm above the isocenter, data was acquired by the Calypso system at 10 Hz to establish the uncertainty in measurements. Transponder positional data was acquired with unilateral hip prostheses of different metallic compositions and then with bilateral hips placed at variable separation from themore » phantom. Results: Regardless of hip prosthesis composition, the average vector displacement in the presence of a unilateral prosthesis was < 0.5 mm. The greatest contribution to overall vector displacement occurred in the lateral dimension. With bilateral hip prosthesis, the average vector displacement was 0.3 mm. The displacement in the lateral dimension was markedly reduced compared with a unilateral hip, suggesting that there was a countervailing effect with bilateral hip prosthesis. The greatest average vector displacement was 0.6 mm and occurred when bilateral hip prostheses were placed within 4 cm of the detector array. Conclusion: Unilateral and bilateral hip prostheses did not have any meaningful effect on the ability to accurately track electromagnetic transponders implanted in a prostate phantom. At clinically realistic distances between the hip and detection array, the average tracking error is negligible.« less

Artificial light on water attracts turtle hatchlings during their near shore transit

PubMed Central

Thums, Michele; Whiting, Scott D.; Reisser, Julia; Pendoley, Kellie L.; Proietti, Maira; Hetzel, Yasha; Fisher, Rebecca; Meekan, Mark G.

2016-01-01

We examined the effect of artificial light on the near shore trajectories of turtle hatchlings dispersing from natal beaches. Green turtle (Chelonia mydas) hatchlings were tagged with miniature acoustic transmitters and their movements tracked within an underwater array of 36 acoustic receivers placed in the near shore zone. A total of 40 hatchlings were tracked, 20 of which were subjected to artificial light during their transit of the array. At the same time, we measured current speed and direction, which were highly variable within and between experimental nights and treatments. Artificial lighting affected hatchling behaviour, with 88% of individual trajectories oriented towards the light and spending, on average, 23% more time in the 2.25 ha tracking array (19.5 ± 5 min) than under ambient light conditions (15.8 ± 5 min). Current speed had little to no effect on the bearing (angular direction) of the hatchling tracks when artificial light was present, but under ambient conditions it influenced the bearing of the tracks when current direction was offshore and above speeds of approximately 32.5 cm s−1. This is the first experimental evidence that wild turtle hatchlings are attracted to artificial light after entering the ocean, a behaviour that is likely to subject them to greater risk of predation. The experimental protocol described in this study can be used to assess the effect of anthropogenic (light pollution, noise, etc.) and natural (wave action, current, wind, moonlight) influences on the in-water movements of sea turtle hatchlings during the early phase of dispersal. PMID:27293795

Artificial light on water attracts turtle hatchlings during their near shore transit.

PubMed

Thums, Michele; Whiting, Scott D; Reisser, Julia; Pendoley, Kellie L; Pattiaratchi, Charitha B; Proietti, Maira; Hetzel, Yasha; Fisher, Rebecca; Meekan, Mark G

2016-05-01

We examined the effect of artificial light on the near shore trajectories of turtle hatchlings dispersing from natal beaches. Green turtle (Chelonia mydas) hatchlings were tagged with miniature acoustic transmitters and their movements tracked within an underwater array of 36 acoustic receivers placed in the near shore zone. A total of 40 hatchlings were tracked, 20 of which were subjected to artificial light during their transit of the array. At the same time, we measured current speed and direction, which were highly variable within and between experimental nights and treatments. Artificial lighting affected hatchling behaviour, with 88% of individual trajectories oriented towards the light and spending, on average, 23% more time in the 2.25 ha tracking array (19.5 ± 5 min) than under ambient light conditions (15.8 ± 5 min). Current speed had little to no effect on the bearing (angular direction) of the hatchling tracks when artificial light was present, but under ambient conditions it influenced the bearing of the tracks when current direction was offshore and above speeds of approximately 32.5 cm s(-1). This is the first experimental evidence that wild turtle hatchlings are attracted to artificial light after entering the ocean, a behaviour that is likely to subject them to greater risk of predation. The experimental protocol described in this study can be used to assess the effect of anthropogenic (light pollution, noise, etc.) and natural (wave action, current, wind, moonlight) influences on the in-water movements of sea turtle hatchlings during the early phase of dispersal.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1992-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1990-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, K.C.

1992-12-08

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion. 16 figs.

CMOS VLSI Active-Pixel Sensor for Tracking

NASA Technical Reports Server (NTRS)

Pain, Bedabrata; Sun, Chao; Yang, Guang; Heynssens, Julie

2004-01-01

An architecture for a proposed active-pixel sensor (APS) and a design to implement the architecture in a complementary metal oxide semiconductor (CMOS) very-large-scale integrated (VLSI) circuit provide for some advanced features that are expected to be especially desirable for tracking pointlike features of stars. The architecture would also make this APS suitable for robotic- vision and general pointing and tracking applications. CMOS imagers in general are well suited for pointing and tracking because they can be configured for random access to selected pixels and to provide readout from windows of interest within their fields of view. However, until now, the architectures of CMOS imagers have not supported multiwindow operation or low-noise data collection. Moreover, smearing and motion artifacts in collected images have made prior CMOS imagers unsuitable for tracking applications. The proposed CMOS imager (see figure) would include an array of 1,024 by 1,024 pixels containing high-performance photodiode-based APS circuitry. The pixel pitch would be 9 m. The operations of the pixel circuits would be sequenced and otherwise controlled by an on-chip timing and control block, which would enable the collection of image data, during a single frame period, from either the full frame (that is, all 1,024 1,024 pixels) or from within as many as 8 different arbitrarily placed windows as large as 8 by 8 pixels each. A typical prior CMOS APS operates in a row-at-a-time ( grolling-shutter h) readout mode, which gives rise to exposure skew. In contrast, the proposed APS would operate in a sample-first/readlater mode, suppressing rolling-shutter effects. In this mode, the analog readout signals from the pixels corresponding to the windows of the interest (which windows, in the star-tracking application, would presumably contain guide stars) would be sampled rapidly by routing them through a programmable diagonal switch array to an on-chip parallel analog memory array. The diagonal-switch and memory addresses would be generated by the on-chip controller. The memory array would be large enough to hold differential signals acquired from all 8 windows during a frame period. Following the rapid sampling from all the windows, the contents of the memory array would be read out sequentially by use of a capacitive transimpedance amplifier (CTIA) at a maximum data rate of 10 MHz. This data rate is compatible with an update rate of almost 10 Hz, even in full-frame operation

Inductrack III configuration--a maglev system for high loads

DOEpatents

Post, Richard F

2015-03-24

Inductrack III configurations are suited for use in transporting heavy freight loads. Inductrack III addresses a problem associated with the cantilevered track of the Inductrack II configuration. The use of a cantilevered track could present mechanical design problems in attempting to achieve a strong enough track system such that it would be capable of supporting very heavy loads. In Inductrack III, the levitating portion of the track can be supported uniformly from below, as the levitating Halbach array used on the moving vehicle is a single-sided one, thus does not require the cantilevered track as employed in Inductrack II.

Inductrack III configuration--a maglev system for high loads

DOEpatents

Post, Richard F

2013-11-12

Inductrack III configurations are suited for use in transporting heavy freight loads. Inductrack III addresses a problem associated with the cantilevered track of the Inductrack II configuration. The use of a cantilevered track could present mechanical design problems in attempting to achieve a strong enough track system such that it would be capable of supporting very heavy loads. In Inductrack III, the levitating portion of the track can be supported uniformly from below, as the levitating Halbach array used on the moving vehicle is a single-sided one, thus does not require the cantilevered track as employed in Inductrack II.

Halbach array type focusing actuator for small and thin optical data storage device

NASA Astrophysics Data System (ADS)

Lee, Sung Q.; Park, Kang-Ho; Paek, Mun Chul

2004-09-01

The small form factor optical data storage devices are developing rapidly nowadays. Since it is designed for portable and compatibility with flesh memory, its components such as disk, head, focusing actuator, and spindle motor should be assembled within 5 mm. The thickness of focusing actuator is within 2 mm and the total working range is +/-100um, with the resolution of less than 1μm. Since the thickness is limited tightly, it is hard to place the yoke that closes the magnetic circuit and hard to make strong flux density without yoke. Therefore, Halbach array is adopted to increase the magnetic flux of one side without yoke. The proposed Halbach array type focusing actuator has the advantage of thin actuation structure with sacrificing less flex density than conventional magnetic array. The optical head unit is moved on the swing arm type tracking actuator. Focusing coil is attached to swing arm, and Halbach magnet array is positioned at the bottom of deck along the tracking line, and focusing actuator exerts force by the Fleming's left hand rule. The dynamics, working range, control resolution of focusing actuator are analyzed and performed.

Analysis and simulation tools for solar array power systems

NASA Astrophysics Data System (ADS)

Pongratananukul, Nattorn

This dissertation presents simulation tools developed specifically for the design of solar array power systems. Contributions are made in several aspects of the system design phases, including solar source modeling, system simulation, and controller verification. A tool to automate the study of solar array configurations using general purpose circuit simulators has been developed based on the modeling of individual solar cells. Hierarchical structure of solar cell elements, including semiconductor properties, allows simulation of electrical properties as well as the evaluation of the impact of environmental conditions. A second developed tool provides a co-simulation platform with the capability to verify the performance of an actual digital controller implemented in programmable hardware such as a DSP processor, while the entire solar array including the DC-DC power converter is modeled in software algorithms running on a computer. This "virtual plant" allows developing and debugging code for the digital controller, and also to improve the control algorithm. One important task in solar arrays is to track the maximum power point on the array in order to maximize the power that can be delivered. Digital controllers implemented with programmable processors are particularly attractive for this task because sophisticated tracking algorithms can be implemented and revised when needed to optimize their performance. The proposed co-simulation tools are thus very valuable in developing and optimizing the control algorithm, before the system is built. Examples that demonstrate the effectiveness of the proposed methodologies are presented. The proposed simulation tools are also valuable in the design of multi-channel arrays. In the specific system that we have designed and tested, the control algorithm is implemented on a single digital signal processor. In each of the channels the maximum power point is tracked individually. In the prototype we built, off-the-shelf commercial DC-DC converters were utilized. At the end, the overall performance of the entire system was evaluated using solar array simulators capable of simulating various I-V characteristics, and also by using an electronic load. Experimental results are presented.

Improved Modeling of Open Waveguide Aperture Radiators for use in Conformal Antenna Arrays

NASA Astrophysics Data System (ADS)

Nelson, Gregory James

Open waveguide apertures have been used as radiating elements in conformal arrays. Individual radiating element model patterns are used in constructing overall array models. The existing models for these aperture radiating elements may not accurately predict the array pattern for TEM waves which are not on boresight for each radiating element. In particular, surrounding structures can affect the far field patterns of these apertures, which ultimately affects the overall array pattern. New models of open waveguide apertures are developed here with the goal of accounting for the surrounding structure effects on the aperture far field patterns such that the new models make accurate pattern predictions. These aperture patterns (both E plane and H plane) are measured in an anechoic chamber and the manner in which they deviate from existing model patterns are studied. Using these measurements as a basis, existing models for both E and H planes are updated with new factors and terms which allow the prediction of far field open waveguide aperture patterns with improved accuracy. These new and improved individual radiator models are then used to predict overall conformal array patterns. Arrays of open waveguide apertures are constructed and measured in a similar fashion to the individual aperture measurements. These measured array patterns are compared with the newly modeled array patterns to verify the improved accuracy of the new models as compared with the performance of existing models in making array far field pattern predictions. The array pattern lobe characteristics are then studied for predicting fully circularly conformal arrays of varying radii. The lobe metrics that are tracked are angular location and magnitude as the radii of the conformal arrays are varied. A constructed, measured array that is close to conforming to a circular surface is compared with a fully circularly conformal modeled array pattern prediction, with the predicted lobe angular locations and magnitudes tracked, plotted and tabulated. The close match between the patterns of the measured array and the modeled circularly conformal array verifies the validity of the modeled circularly conformal array pattern predictions.

Nanosilicon dot arrays with a bit pitch and a track pitch of 25 nm formed by electron-beam drawing and reactive ion etching for 1 Tbit/in.{sup 2} storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosaka, Sumio; Sano, Hirotaka; Shirai, Masumi

2006-11-27

The formation of very fine Si dots with a bit pitch and a track pitch of less than 25 nm using electron-beam (EB) lithography on ZEP520 and calixarene EB resists and CF{sub 4} reactive ion etching has been demonstrated. The experimental results indicate that the calixarene resist is very suitable for forming an ultrahigh-packed bit array pattern of Si dots. This result promises to open the way toward 1 Tbit/in.{sup 2} storage using patterned media with a dot size of <15 nm.

Track reconstruction and background rejection for the Baikal neutrino telescope

NASA Astrophysics Data System (ADS)

Belolaptikov, I. A.; Djilkibaev, J.-A. M.; Domogatsky, G. V.; Klimushin, S. I.; Krabi, J.; Lanin, O. Ju.; Osipova, E. A.; Pavlov, A. A.; Spiering, Ch.; Wischnewski, R.

1994-05-01

We describe procedures to reconstruct muon tracks in the Baikal Neutrino Telescope including effective filtering of badly reconstructed events. Special attention is payed to reject downward going muons faking upward going muons from neutrino interactions. It is shown that a rejection factor of 106-as it is needed to operate a neutrino telescope at 1100 m.w.e. depth - can be obtained with a 200 PMT array. We present first results from NT-36, the 1993 array consisting of 36 PMTs. We observe satisfying agreement between Monte Carlo results and experimental data. This gives us confidence to our simulations of the full detector.

Methods for utilizing maximum power from a solar array

NASA Technical Reports Server (NTRS)

Decker, D. K.

1972-01-01

A preliminary study of maximum power utilization methods was performed for an outer planet spacecraft using an ion thruster propulsion system and a solar array as the primary energy source. The problems which arise from operating the array at or near the maximum power point of its 1-V characteristic are discussed. Two closed loop system configurations which use extremum regulators to track the array's maximum power point are presented. Three open loop systems are presented that either: (1) measure the maximum power of each array section and compute the total array power, (2) utilize a reference array to predict the characteristics of the solar array, or (3) utilize impedance measurements to predict the maximum power utilization. The advantages and disadvantages of each system are discussed and recommendations for further development are made.

Design and economics of a photovoltaic concentrator array for off-grid applications

NASA Astrophysics Data System (ADS)

Maish, A. B.; Rios, M., Jr.

1982-09-01

The array design and expected operation of a photovoltaic concentrator are discussed. A second generation stand alone 680 W/sub p/ photovoltaic (PV) concentrating array for low power, nongrid connected applications was designed. The array consists of six passive cooled point focus Fresnel lens concentrating modules on a two axis polar mount tracking structure. The new array design incorporates several major improvements to the first generation design. These include 50% more array area and a control system which allows unattended, fully automatic operation. The life cycle energy costs are calculated and compared to the equivalent energy costs of a 3 kW diesel electric generator set and an equivalent flat panel PV system.

Graphical Environment Tools for Application to Gamma-Ray Energy Tracking Arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todd, Richard A.; Radford, David C.

2013-12-30

Highly segmented, position-sensitive germanium detector systems are being developed for nuclear physics research where traditional electronic signal processing with mixed analog and digital function blocks would be enormously complex and costly. Future systems will be constructed using pipelined processing of high-speed digitized signals as is done in the telecommunications industry. Techniques which provide rapid algorithm and system development for future systems are desirable. This project has used digital signal processing concepts and existing graphical system design tools to develop a set of re-usable modular functions and libraries targeted for the nuclear physics community. Researchers working with complex nuclear detector arraysmore » such as the Gamma-Ray Energy Tracking Array (GRETA) have been able to construct advanced data processing algorithms for implementation in field programmable gate arrays (FPGAs) through application of these library functions using intuitive graphical interfaces.« less

Position and orientation tracking system

DOEpatents

Burks, Barry L.; DePiero, Fred W.; Armstrong, Gary A.; Jansen, John F.; Muller, Richard C.; Gee, Timothy F.

1998-01-01

A position and orientation tracking system presents a laser scanning appaus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle.

Position and orientation tracking system

DOEpatents

Burks, B.L.; DePiero, F.W.; Armstrong, G.A.; Jansen, J.F.; Muller, R.C.; Gee, T.F.

1998-05-05

A position and orientation tracking system presents a laser scanning apparatus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle. 14 figs.

Evaluation of Kapton pyrolysis, arc tracking, and arc propagation on the Space Station Freedom (SSF) solar array Flexible Current Carrier (FCC)

NASA Technical Reports Server (NTRS)

Stueber, Thomas J.

1991-01-01

Recent studies involving the use of polyimide Kapton coated wires indicate that if a momentary electrical short circuit occurs between two wires, sufficient heating of the Kapton can occur to thermally char (pyrolyze) the Kapton. Such charred Kapton has sufficient electrical conductivity to create an arc which tracks down the wires and possibly propagates to adjoining wires. These studies prompted an investigation to ascertain the likelihood of the Kapton pyrolysis, arc tracking and propagation phenomena, and the magnitude of destruction conceivably inflicted on Space Station Freedom's (SSF) Flexible Current Carrier (FCC) for the photovoltaic array. The geometric layout of the FCC, having a planar-type orientation as opposed to bundles, may reduce the probability of sustaining an arc. An experimental investigation was conducted to simulate conditions under which an arc can occur on the FCC of SSF, and the consequences of arc initiation.

Evaluation of Kapton pyrolysis, arc tracking, and arc propagation on the Space Station Freedom (SSF) solar array flexible current carrier (FCC)

NASA Technical Reports Server (NTRS)

Stueber, Thomas J.

1991-01-01

Recent studies involving the use of polyimide Kapton coated wires indicate that if a momentary electrical short circuit occurs between two wires, sufficient heating of the Kapton can occur to themally chlar (pyrolyze) the Kapton. Such charred Kapton has sufficient electricxl conductivity to create an arc which tracks down the wires and possibly propagates to adjoining wires. These studies prompted an invetigation to ascertain the likelihood of Kapton pyrolysis, arc tracking and propagation phenomena, and the magnitude of destruction conceivably inflicted on Space Station Freedom's (SSF's) Flexible Current Carrier (FCC) for the photovoltaic array. The geometric layout of the FCC, having a planar-type orientation as opposed to bundles, may reduce the probability of sustaining an arc. An experimental investigation was conducted to simulate conditions under which an arc can occur on the FCC of the SSF, and the consequences of arc initiation.

Effects of design on cost of flat-plate solar photovoltaic arrays for terrestrial central station power applications

NASA Technical Reports Server (NTRS)

Tsou, P.; Stolte, W.

1978-01-01

The paper examines the impact of module and array designs on the balance-of-plant costs for flat-plate terrestrial central station power applications. Consideration is given to the following types of arrays: horizontal, tandem, augmented, tilt adjusted, and E-W tracking. The life-cycle cost of a 20-year plant life serves as the costing criteria for making design and cost tradeoffs. A tailored code of accounts is developed for determining consistent photovoltaic power plant costs and providing credible photovoltaic system cost baselines for flat-plate module and array designs by costing several varying array design approaches.

The statistics of laser returns from cube-corner arrays on satellite

NASA Technical Reports Server (NTRS)

Lehr, C. G.

1973-01-01

A method first presented by Goodman is used to derive an equation for the statistical effects associated with laser returns from satellites having retroreflecting arrays of cube corners. The effect of the distribution on the returns of a satellite-tracking system is illustrated by a computation based on randomly generated numbers.

Radiation Pressure Forces, the Anomalous Acceleration, and Center of Mass Motion for the TOPEX/POSEIDON Spacecraft

NASA Technical Reports Server (NTRS)

Kubitschek, Daniel G.; Born, George H.

2000-01-01

Shortly after launch of the TOPEX/POSEIDON (T/P) spacecraft (s/c), the Precision Orbit Determination (POD) Team at NASA's Goddard Space Flight Center (GSFC) and the Center for Space Research at the University of Texas, discovered residual along-track accelerations, which were unexpected. Here, we describe the analysis of radiation pressure forces acting on the T/P s/c for the purpose of understanding and providing an explanation for the anomalous accelerations. The radiation forces acting on the T/P solar army, which experiences warping due to temperature gradients between the front and back surfaces, are analyzed and the resulting along-track accelerations are determined. Characteristics similar to those of the anomalous acceleration are seen. This analysis led to the development of a new radiation form model, which includes solar array warping and a solar array deployment deflection of as large as 2 deg. As a result of this new model estimates of the empirical along-track acceleration are reduced in magnitude when compared to the GSFC tuned macromodel and are less dependent upon beta(prime), the location of the Sun relative to the orbit plane. If these results we believed to reflect the actual orientation of the T/P solar array then motion of the solar array must influence the location of the s/c center of mass. Preliminary estimates indicate that the center of mass can vary by as much as 3 cm in the radial component of the s/c's position due to rotation of the deflected, warped solar array panel .The altimeter measurements rely upon accurate knowledge of the center of mass location relative to the s/c frame of reference. Any radial motion of the center of mass directly affects the altimeter measurements.

Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope

NASA Technical Reports Server (NTRS)

Bloser, P. F.; Hunter, S. D.; Ryan, J. M.; McConnell, M. L.; Miller, R. S.; Jackson, T. N.; Bai, B.; Jung, S.

2003-01-01

We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.

Comparison of Photovoltaic Energy Systems for the Solar Village

DTIC Science & Technology

1988-08-01

power -point-trackIng ( MPPT ) for the array. It also Includes AC and DC contactors, an isolation transformer, and a control system that fully automates...the day when the array is producing power , the battery controller uses excess array power , not needed for household use , to recharge the batteries. As...alone design) The battery controller used Is the Balance of System Specialists, Inc. Power Control Series model *8104820 rated at 48 volt, 20 amp. This

Tracking the global maximum power point of PV arrays under partial shading conditions

NASA Astrophysics Data System (ADS)

Fennich, Meryem

This thesis presents the theoretical and simulation studies of the global maximum power point tracking (MPPT) for photovoltaic systems under partial shading. The main goal is to track the maximum power point of the photovoltaic module so that the maximum possible power can be extracted from the photovoltaic panels. When several panels are connected in series with some of them shaded partially either due to clouds or shadows from neighboring buildings, several local maxima appear in the power vs. voltage curve. A power increment based MPPT algorithm is effective in identifying the global maximum from the several local maxima. Several existing MPPT algorithms are explored and the state-of-the-art power increment method is simulated and tested for various partial shading conditions. The current-voltage and power-voltage characteristics of the PV model are studied under different partial shading conditions, along with five different cases demonstrating how the MPPT algorithm performs when shading switches from one state to another. Each case is supplemented with simulation results. The method of tracking the Global MPP is based on controlling the DC-DC converter connected to the output of the PV array. A complete system simulation including the PV array, the direct current to direct current (DC-DC) converter and the MPPT is presented and tested using MATLAB software. The simulation results show that the MPPT algorithm works very well with the buck converter, while the boost converter needs further changes and implementation.

Tracking a convoy of multiple targets using acoustic sensor data

NASA Astrophysics Data System (ADS)

Damarla, T. R.

2003-08-01

In this paper we present an algorithm to track a convoy of several targets in a scene using acoustic sensor array data. The tracking algorithm is based on template of the direction of arrival (DOA) angles for the leading target. Often the first target is the closest target to the sensor array and hence the loudest with good signal to noise ratio. Several steps were used to generate a template of the DOA angle for the leading target, namely, (a) the angle at the present instant should be close to the angle at the previous instant and (b) the angle at the present instant should be within error bounds of the predicted value based on the previous values. Once the template of the DOA angles of the leading target is developed, it is used to predict the DOA angle tracks of the remaining targets. In order to generate the tracks for the remaining targets, a track is established if the angles correspond to the initial track values of the first target. Second the time delay between the first track and the remaining tracks are estimated at the highest correlation points between the first track and the remaining tracks. As the vehicles move at different speeds the tracks either compress or expand depending on whether a target is moving fast or slow compared to the first target. The expansion and compression ratios are estimated and used to estimate the predicted DOA angle values of the remaining targets. Based on these predicted DOA angles of the remaining targets the DOA angles obtained from the MVDR or Incoherent MUSIC will be appropriately assigned to proper tracks. Several other rules were developed to avoid mixing the tracks. The algorithm is tested on data collected at Aberdeen Proving Ground with a convoy of 3, 4 and 5 vehicles. Some of the vehicles are tracked and some are wheeled vehicles. The tracking algorithm results are found to be good. The results will be presented at the conference and in the paper.

Quality assurance for clinical implementation of an electromagnetic tracking system.

PubMed

Santanam, Lakshmi; Noel, Camille; Willoughby, Twyla R; Esthappan, Jacqueline; Mutic, Sasa; Klein, Eric E; Low, Daniel A; Parikh, Parag J

2009-08-01

The Calypso Medical 4D localization system utilizes alternating current electromagnetics for accurate, real-time tumor tracking. A quality assurance program to clinically implement this system is described here. Testing of the continuous electromagnetic tracking system (Calypso Medical Technologies, Seattle, WA) was performed using an in-house developed four-dimensional stage and a quality assurance fixture containing three radiofrequency transponders at independently measured locations. The following tests were performed to validate the Calypso system: (a) Localization and tracking accuracy, (b) system reproducibility, (c) measurement of the latency of the tracking system, and (d) measurement of transmission through the Calypso table overlay and the electromagnetic array. The translational and rotational localization accuracies were found to be within 0.01 cm and 1.0 degree, respectively. The reproducibility was within 0.1 cm. The average system latency was measured to be within 303 ms. The attenuation by the Calypso overlay was measured to be 1.0% for both 6 and 18 MV photons. The attenuations by the Calypso array were measured to be 2% and 1.5% for 6 and 18 MV photons, respectively. For oblique angles, the transmission was measured to be 3% for 6 MV, while it was 2% for 18 MV photons. A quality assurance process has been developed for the clinical implementation of an electromagnetic tracking system in radiation therapy.

Passive acoustic tracking of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground.

PubMed

Stanistreet, Joy E; Risch, Denise; Van Parijs, Sofie M

2013-01-01

Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring.

Passive Acoustic Tracking of Singing Humpback Whales (Megaptera novaeangliae) on a Northwest Atlantic Feeding Ground

PubMed Central

Stanistreet, Joy E.; Risch, Denise; Van Parijs, Sofie M.

2013-01-01

Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring. PMID:23593447

Multi-baseline bootstrapping at the Navy precision optical interferometer

NASA Astrophysics Data System (ADS)

Armstrong, J. T.; Schmitt, H. R.; Mozurkewich, D.; Jorgensen, A. M.; Muterspaugh, M. W.; Baines, E. K.; Benson, J. A.; Zavala, Robert T.; Hutter, D. J.

2014-07-01

The Navy Precision Optical Interferometer (NPOI) was designed from the beginning to support baseline boot- strapping with equally-spaced array elements. The motivation was the desire to image the surfaces of resolved stars with the maximum resolution possible with a six-element array. Bootstrapping two baselines together to track fringes on a third baseline has been used at the NPOI for many years, but the capabilities of the fringe tracking software did not permit us to bootstrap three or more baselines together. Recently, both a new backend (VISION; Tennessee State Univ.) and new hardware and firmware (AZ Embedded Systems and New Mexico Tech, respectively) for the current hybrid backend have made multi-baseline bootstrapping possible.

The FINUDA straw tube detector

NASA Astrophysics Data System (ADS)

Zia, A.; Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Lucherini, V.; Mecozzi, A.; Pace, E.; Passamonti, L.; Qaiser, N.; Russo, V.; Tomassini, S.; Sarwar, S.; Serdyouk, V.

2001-04-01

An array of 2424 2.6- m-long, 15- mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled at National Laboratories of Frascati of INFN for the FINUDA experiment. The array covers a cylindrical tracking surface of 18 m 2 and provides coordinate measurement in the drift direction and along the wire with a resolution of the order of 100 and 300 μm, respectively. The array has finished the commissioning phase and tests with cosmic rays are underway. The status straw tubes array and a very preliminary result from cosmic rays test are summarized in this work.

High-speed electronic beam steering using injection locking of a laser-diode array

NASA Astrophysics Data System (ADS)

Swanson, E. A.; Abbas, G. L.; Yang, S.; Chan, V. W. S.; Fujimoto, J. G.

1987-01-01

High-speed electronic steering of the output beam of a 10-stripe laser-diode array is reported. The array was injection locked to a single-frequency laser diode. High-speed steering of the locked 0.5-deg-wide far-field lobe is demonstrated either by modulating the injection current of the array or by modulating the frequency of the master laser. Closed-loop tracking bandwidths of 70 kHz and 3 MHz, respectively, were obtained. The beam-steering bandwidths are limited by the FM responses of the modulated devices for both techniques.

Silicon solar photovoltaic power stations

NASA Technical Reports Server (NTRS)

Chowaniec, C. R.; Ferber, R. R.; Pittman, P. F.; Marshall, B. W.

1977-01-01

Modular design of components and arrays, cost estimates for modules and support structures, and cost/performance analysis of a central solar photovoltaic power plant are discussed. Costs of collector/reflector arrays are judged the dominant element in the total capital investment. High-concentration solar tracking arrays are recommended as the most economic means for producing solar photovoltaic energy when solar cells costs are high ($500 per kW generated). Capital costs for power conditioning subsystem components are itemized and system busbar energy costs are discussed at length.

Tracking and Characterization of Aircraft Wakes Using Acoustic and Lidar Measurements

NASA Technical Reports Server (NTRS)

Booth, Earl R., Jr.; Humphreys, William M., Jr.

2005-01-01

Data from the 2003 Denver International Airport Wake Acoustics Test are further examined to discern spectral content of aircraft wake signatures, and to compare three dimensional wake tracking from acoustic data to wake tracking data obtained through use of continuous wave and pulsed lidar. Wake tracking data derived from acoustic array data agree well with both continuous wave and pulsed lidar in the horizontal plane, but less well with pulsed lidar in the vertical direction. Results from this study show that the spectral distribution of acoustic energy in a wake signature varies greatly with aircraft type.

Commercial-Off-The-Shelf Vehicles for Towed Array Magnetometry

DTIC Science & Technology

2009-09-01

a steering wheel, and brake and accelerator pedals like a car. By way of example, a ubiquitous side-by- side UTV is the John Deere Gator. The...tire tracks are imperfectly 42 followed. These new tracks will be at a slightly different angle , and one set of biases will not be able to take...tracks at an angle relative to the north-south traverses that we ran. In addition, we surveyed into the muddy wet section at the western end of the site

An Array of Optical Receivers for Deep-Space Communications

NASA Technical Reports Server (NTRS)

Vilnrotter, Chi-Wung; Srinivasan, Meera; Andrews, Kenneth

2007-01-01

An array of small optical receivers is proposed as an alternative to a single large optical receiver for high-data-rate communications in NASA s Deep Space Network (DSN). Because the telescope for a single receiver capable of satisfying DSN requirements must be greater than 10 m in diameter, the design, building, and testing of the telescope would be very difficult and expensive. The proposed array would utilize commercially available telescopes of 1-m or smaller diameter and, therefore, could be developed and verified with considerably less difficulty and expense. The essential difference between a single-aperture optical-communications receiver and an optical-array receiver is that a single-aperture receiver focuses all of the light energy it collects onto the surface of an optical detector, whereas an array receiver focuses portions of the total collected energy onto separate detectors, optically detects each fractional energy component, then combines the electrical signal from the array of detector outputs to form the observable, or "decision statistic," used to decode the transmitted data. A conceptual block diagram identifying the key components of the optical-array receiver suitable for deep-space telemetry reception is shown in the figure. The most conspicuous feature of the receiver is the large number of small- to medium-size telescopes, with individual apertures and number of telescopes selected to make up the desired total collecting area. This array of telescopes is envisioned to be fully computer- controlled via the user interface and prediction-driven to achieve rough pointing and tracking of the desired spacecraft. Fine-pointing and tracking functions then take over to keep each telescope pointed toward the source, despite imperfect pointing predictions, telescope-drive errors, and vibration caused by wind.

Characterization of the electrical output of flat-plate photovoltaic arrays

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Hill, G. M.; Ross, R. G., Jr.

1982-01-01

The electric output of flat-plate photovoltaic arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as direct-current to alternating-current power conditioners must be able to accommodate widely varying input levels, while maintaining operation at or near the array maximum power point.The results of an extensive computer simulation study that was used to define the parameters necessary for the systematic design of array/power-conditioner interfaces are presented as normalized ratios of power-conditioner parameters to array parameters, to make the results universally applicable to a wide variety of system sizes, sites, and operating modes. The advantages of maximum power tracking and a technique for computing average annual power-conditioner efficiency are discussed.

In vivo visualization of robotically implemented synthetic tracked aperture ultrasound (STRATUS) imaging system using curvilinear array

NASA Astrophysics Data System (ADS)

Zhang, Haichong K.; Aalamifar, Fereshteh; Boctor, Emad M.

2016-04-01

Synthetic aperture for ultrasound is a technique utilizing a wide aperture in both transmit and receive to enhance the ultrasound image quality. The limitation of synthetic aperture is the maximum available aperture size limit determined by the physical size of ultrasound probe. We propose Synthetic-Tracked Aperture Ultrasound (STRATUS) imaging system to overcome the limitation by extending the beamforming aperture size through ultrasound probe tracking. With a setup involving a robotic arm, the ultrasound probe is moved using the robotic arm, while the positions on a scanning trajectory are tracked in real-time. Data from each pose are synthesized to construct a high resolution image. In previous studies, we have demonstrated the feasibility through phantom experiments. However, various additional factors such as real-time data collection or motion artifacts should be taken into account when the in vivo target becomes the subject. In this work, we build a robot-based STRATUS imaging system with continuous data collection capability considering the practical implementation. A curvilinear array is used instead of a linear array to benefit from its wider capture angle. We scanned human forearms under two scenarios: one submerged the arm in the water tank under 10 cm depth, and the other directly scanned the arm from the surface. The image contrast improved 5.51 dB, and 9.96 dB for the underwater scan and the direct scan, respectively. The result indicates the practical feasibility of STRATUS imaging system, and the technique can be potentially applied to the wide range of human body.

Feasibility Study of Utilizing Existing Infrared Array Cameras for Daylight Star Tracking on NASA's Ultra Long Duration Balloon (ULDB) Missions

NASA Technical Reports Server (NTRS)

Tueller, Jack (Technical Monitor); Fazio, Giovanni G.; Tolls, Volker

2004-01-01

The purpose of this study was to investigate the feasibility of developing a daytime star tracker for ULDB flights using a commercially available off-the-shelf infrared array camera. This report describes the system used for ground-based tests, the observations, the test results, and gives recommendations for continued development.

Control, Filtering and Prediction for Phased Arrays in Directed Energy Systems

DTIC Science & Technology

2016-04-30

adaptive optics. 15. SUBJECT TERMS control, filtering, prediction, system identification, adaptive optics, laser beam pointing, target tracking, phase... laser beam control; furthermore, wavefront sensors are plagued by the difficulty of maintaining the required alignment and focusing in dynamic mission...developed new methods for filtering, prediction and system identification in adaptive optics for high energy laser systems including phased arrays. The

A Hybrid, Large-Scale Wireless Sensor Network for Real-Time Acquisition and Tracking

DTIC Science & Technology

2007-06-01

multicolor, Quantum Well Infrared Photodetector ( QWIP ), step-stare, large-format Focal Plane Array (FPA) is proposed and evaluated through performance...Photodetector ( QWIP ), step-stare, large-format Focal Plane Array (FPA) is proposed and evaluated through performance analysis. The thesis proposes...7 1. Multi-color IR Sensors - Operational Advantages ...........................8 2. Quantum-Well IR Photodetector ( QWIP

Stability Measurements for Alignment of the NIF Neutron Imaging System Pinhole Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fittinghoff, D N; Bower, D E; Drury, O B

2011-03-29

The alignment system for the National Ignition Facility's neutron imaging system has been commissioned and measurements of the relative stability of the 90-315 DIM, the front and the back of the neutron imaging pinhole array and an exploding pusher target have been made using the 90-135 and the 90-258 opposite port alignment systems. Additionally, a laser beam shot from the neutron-imaging Annex and reflected from a mirror at the back of the pinhole array was used to monitor the pointing of the pinhole. Over a twelve hour period, the relative stability of these parts was found to be within {approx}more » {+-}18 {micro}m rms even when using manual methods for tracking the position of the objects. For highly visible features, use of basic particle tracking techniques found that the front of the pinhole array was stable relative to the 90-135 opposite port alignment camera to within {+-}3.4 {micro}m rms. Reregistration, however, of the opposite port alignment systems themselves using the target alignment sensor was found to change the expected position of target chamber center by up to 194 {micro}m.« less

Multi-viewer tracking integral imaging system and its viewing zone analysis.

PubMed

Park, Gilbae; Jung, Jae-Hyun; Hong, Keehoon; Kim, Yunhee; Kim, Young-Hoon; Min, Sung-Wook; Lee, Byoungho

2009-09-28

We propose a multi-viewer tracking integral imaging system for viewing angle and viewing zone improvement. In the tracking integral imaging system, the pickup angles in each elemental lens in the lens array are decided by the positions of viewers, which means the elemental image can be made for each viewer to provide wider viewing angle and larger viewing zone. Our tracking integral imaging system is implemented with an infrared camera and infrared light emitting diodes which can track the viewers' exact positions robustly. For multiple viewers to watch integrated three-dimensional images in the tracking integral imaging system, it is needed to formulate the relationship between the multiple viewers' positions and the elemental images. We analyzed the relationship and the conditions for the multiple viewers, and verified them by the implementation of two-viewer tracking integral imaging system.

FPGA-based Trigger System for the Fermilab SeaQuest Experimentz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiu, Shiuan-Hal; Wu, Jinyuan; McClellan, Randall Evan

The SeaQuest experiment (Fermilab E906) detects pairs of energetic μ + and μ -produced in 120 GeV/c proton–nucleon interactions in a high rate environment. The trigger system we used consists of several arrays of scintillator hodoscopes and a set of field-programmable gate array (FPGA) based VMEbus modules. Signals from up to 96 channels of hodoscope are digitized by each FPGA with a 1-ns resolution using the time-to-digital convertor (TDC) firmware. The delay of the TDC output can be adjusted channel-by-channel in 1-ns step and then re-aligned with the beam RF clock. The hit pattern on the hodoscope planes is thenmore » examined against pre-determined trigger matrices to identify candidate muon tracks. Finally, information on the candidate tracks is sent to the 2nd-level FPGA-based track correlator to find candidate di-muon events. The design and implementation of the FPGA-based trigger system for SeaQuest experiment are presented.« less

FPGA-based trigger system for the Fermilab SeaQuest experimentz

NASA Astrophysics Data System (ADS)

Shiu, Shiuan-Hal; Wu, Jinyuan; McClellan, Randall Evan; Chang, Ting-Hua; Chang, Wen-Chen; Chen, Yen-Chu; Gilman, Ron; Nakano, Kenichi; Peng, Jen-Chieh; Wang, Su-Yin

2015-12-01

The SeaQuest experiment (Fermilab E906) detects pairs of energetic μ+ and μ- produced in 120 GeV/c proton-nucleon interactions in a high rate environment. The trigger system consists of several arrays of scintillator hodoscopes and a set of field-programmable gate array (FPGA) based VMEbus modules. Signals from up to 96 channels of hodoscope are digitized by each FPGA with a 1-ns resolution using the time-to-digital convertor (TDC) firmware. The delay of the TDC output can be adjusted channel-by-channel in 1-ns step and then re-aligned with the beam RF clock. The hit pattern on the hodoscope planes is then examined against pre-determined trigger matrices to identify candidate muon tracks. Information on the candidate tracks is sent to the 2nd-level FPGA-based track correlator to find candidate di-muon events. The design and implementation of the FPGA-based trigger system for SeaQuest experiment are presented.

FPGA-based Trigger System for the Fermilab SeaQuest Experimentz

DOE PAGES

Shiu, Shiuan-Hal; Wu, Jinyuan; McClellan, Randall Evan; ...

2015-09-10

The SeaQuest experiment (Fermilab E906) detects pairs of energetic μ + and μ -produced in 120 GeV/c proton–nucleon interactions in a high rate environment. The trigger system we used consists of several arrays of scintillator hodoscopes and a set of field-programmable gate array (FPGA) based VMEbus modules. Signals from up to 96 channels of hodoscope are digitized by each FPGA with a 1-ns resolution using the time-to-digital convertor (TDC) firmware. The delay of the TDC output can be adjusted channel-by-channel in 1-ns step and then re-aligned with the beam RF clock. The hit pattern on the hodoscope planes is thenmore » examined against pre-determined trigger matrices to identify candidate muon tracks. Finally, information on the candidate tracks is sent to the 2nd-level FPGA-based track correlator to find candidate di-muon events. The design and implementation of the FPGA-based trigger system for SeaQuest experiment are presented.« less

Improvements to Passive Acoustic Tracking Methods for Marine Mammal Monitoring

DTIC Science & Technology

2016-05-02

individual animals . 15. SUBJECT TERMS Marine mammal; Passive acoustic monitoring ; Localization; Tracking ; Multiple source ; Sparse array 16. SECURITY...al. 2004; Thode 2005; Nosal 2007] to localize animals in situations where straight-line propagation assumptions made by conventional marine mammal...Objective 1: Inveti for sound speed profiles. hydrophone position and hydrophone timing offset in addition to animal position Almost all marine mammal

UAVSAR Active Electronically Scanned Array

NASA Technical Reports Server (NTRS)

Sadowy, Gregory, A.; Chamberlain, Neil F.; Zawadzki, Mark S.; Brown, Kyle M.; Fisher, Charles D.; Figueroa, Harry S.; Hamilton, Gary A.; Jones, Cathleen E.; Vorperian, Vatche; Grando, Maurio B.

2011-01-01

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronically scanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

A real-time sub-μrad laser beam tracking system

NASA Astrophysics Data System (ADS)

Buske, Ivo; Schragner, Ralph; Riede, Wolfgang

2007-10-01

We present a rugged and reliable real-time laser beam tracking system operating with a high speed, high resolution piezo-electric tip/tilt mirror. Characteristics of the piezo mirror and position sensor are investigated. An industrial programmable automation controller is used to develop a real-time digital PID controller. The controller provides a one million field programmable gate array (FPGA) to realize a high closed-loop frequency of 50 kHz. Beam tracking with a root-mean-squared accuracy better than 0.15 μrad has been laboratory confirmed. The system is intended as an add-on module for established mechanical mrad tracking systems.

Simulation of solar array slewing of Indian remote sensing satellite

NASA Astrophysics Data System (ADS)

Maharana, P. K.; Goel, P. S.

The effect of flexible arrays on sun tracking for the IRS satellite is studied. Equations of motion of satellites carrying a rotating flexible appendage are developed following the Newton-Euler approach and utilizing the constrained modes of the appendage. The drive torque, detent torque and friction torque in the SADA are included in the model. Extensive simulations of the slewing motion are carried out. The phenomena of back-stepping, step-missing, step-slipping and the influences of array flexibility in the acquisition mode are observed for certain combinations of parameters.

A Method of Maximum Power Control in Single-phase Utility Interactive Photovoltaic Generation System by using PWM Current Source Inverter

NASA Astrophysics Data System (ADS)

Neba, Yasuhiko

This paper deals with a maximum power point tracking (MPPT) control of the photovoltaic generation with the single-phase utility interactive inverter. The photovoltaic arrays are connected by employing the PWM current source inverter to the utility. The use of the pulsating dc current and voltage allows the maximum power point to be searched. The inverter can regulate the array voltage and keep the arrays to the maximum power. This paper gives the control method and the experimental results.

Current status of the expanded GRAPES collaboration experiment at Ooty in India

NASA Astrophysics Data System (ADS)

Gupta, S.K.; Anita, H.M.; Iyer, A.; Jagadeesan, P.; Jain, A.; Karthikeyan, S.; Manoharan, P.K.; Mohanty, P.K.; Nayak, P.K.; Rao, B.S.; Ravindran, K.C.; Tanaka, H.; Tonwar, S.C.; Ogio, S.; Okuda, T.; Oshima, A.; Shimizu, N.; Yoshikoshi, T.; Badruddin; Hasan, R.; Ahmad, Shakeel; Mishra, A.P.; Shrivastava, P.K.; Koul, R.; Shah, G.N.; Mir, T.A.; Mufti, S.; Raha, S.; Ghosh, S.; Joarder, P.; Saha, S.; Boruah, K.; Datta, P.; Boruah, P.K.; Baruah, A.G.; Baishya, R.; Saikia, J.; Banerjee, D.; Subramanian, P.; Bhadra, A.; Kumar, S.; Agarwal, R.; Dubey, S.K.; Bhattacharjee, P.

GRAPES-3 experiment employs a high-density array of scintillators and a large area tracking muon telescope. The GRAPES collaboration is being expanded with addition of several major facilities. These include a Cerenkov telescope and low frequency dipole array for the measurement of shower energy. Addition of several modules of muon telescopes to cover a larger area, expansion of the scintillator array with greater separation between detectors. Installation of a neutron monitor is also planned. The current status of the experiment would be summarized.

Comparison of Two Detection Combination Algorithms for Phased Array Radars

DTIC Science & Technology

2015-07-01

data were generated by a simulator of multi-function radar ( MFR ) and the combination algorithms are evaluated with the recorded simulation data. With...electronically scanned phased array Multi-Function Radar ( MFR ), is a type of radar whose transmitter and receiver functions are composed of numerous...small transmit/receive modules. An MFR can perform many functions previously performed by individual, dedicated radars for search, tracking and

Terrestrial central station array life-cycle analysis support study

NASA Technical Reports Server (NTRS)

1978-01-01

Plant elements evaluated included designs for module, panel and array structures, as well as balance-of-plant systems. Installation and maintenance procedures and the impact of site environment were also evaluated. In terms of the cost of energy produced, the horizontal array configuration was found to be less expensive than the tandem array at latitudes less than 40 deg. Both of these configurations are less expensive than the rack design. However, the costs of energy for all three configurations are within approximately ?10 percent of each other. For flat plate panels, the seasonally adjusted and tracking array configurations are not economically attractive when compared to the three other designs. Balance-of-plant costs are approximately equal to (goal) module costs. The array structures and foundations are the most expensive items in the balance-of-plant costs.

Marine Bioacoustics: Soundtracks for the Future

DTIC Science & Technology

2013-09-30

studying humpback whale ecology. During summer courses, we provide students 1.) with a strong conceptual understanding of marine bioacoustics theory...localize and track vocalizing humpback whales . 2 During the summer course, we conducted a multi-frequency acoustic survey of Saanich Inlet, BC... humpback whales can be localized and tracked with hydrophone array deployed on Wave Gliders. Paper from this project will be presented at the 20th

SU-G-JeP1-01: A Combination of Real Time Electromagnetic Localization and Tracking with Cone Beam Computed Tomography in Stereotactic Radiosurgery for Brain Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muralidhar, K Raja; Pangam, Suresh; Ponaganti, Srinivas

2016-06-15

Purpose: 1. online verification of patient position during treatment using calypso electromagnetic localization and tracking system. 2. Verification and comparison of positional accuracy between cone beam computed tomography and calypso system. 3. Presenting the advantage of continuation localization in Stereotactic radiosurgery treatments. Methods: Ten brain tumor cases were taken for this study. Patients with head mask were under gone Computed Tomography (CT). Before scanning, mask was cut on the fore head area to keep surface beacons on the skin. Slice thickness of 0.65 mm were taken for this study. x, y, z coordinates of these beacons in TPS were enteredmore » into tracking station. Varian True Beam accelerator, equipped with On Board Imager was used to take Cone beam Computed Tomography (CBCT) to localize the patient. Simultaneously Surface beacons were used to localize and track the patient throughout the treatment. The localization values were compared in both systems. For localization CBCT considered as reference. Tracking was done throughout the treatment using Calypso tracking system using electromagnetic array. This array was in tracking position during imaging and treatment. Flattening Filter free beams of 6MV photons along with Volumetric Modulated Arc Therapy was used for the treatment. The patient movement was observed throughout the treatment ranging from 2 min to 4 min. Results: The average variation observed between calypso system and CBCT localization was less than 0.5 mm. These variations were due to manual errors while keeping beacon on the patient. Less than 0.05 cm intra-fraction motion was observed throughout the treatment with the help of continuous tracking. Conclusion: Calypso target localization system is one of the finest tools to perform radiosurgery in combination with CBCT. This non radiographic method of tracking is a real beneficial method to treat patients confidently while observing real-time motion information of the patient.« less

A Phased Array of Widely Separated Antennas for Space Communication and Planetary Radar

NASA Astrophysics Data System (ADS)

Geldzahler, B.; Bershad, C.; Brown, R.; Cox, R.; Hoblitzell, R.; Kiriazes, J.; Ledford, B.; Miller, M.; Woods, G.; Cornish, T.; D'Addario, L.; Davarian, F.; Lee, D.; Morabito, D.; Tsao, P.; Soloff, J.; Church, K.; Deffenbaugh, P.; Abernethy, K.; Anderson, W.; Collier, J.; Wellen, G.

NASA has successfully demonstrated coherent uplink arraying with real time compensation for atmospheric phase fluctuations at 7.145-7.190 GHz (X-band) and is pursuing a similar demonstration 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida. In addition, we have done the same demonstration with up to three 34m antennas separated by 250m at the Goldstone Deep Space Communication Complex in California at X-band 7.1 GHz. We have begun to infuse the capability at Goldstone into the Deep Space Network to provide a quasi-operational system. Such a demonstration can enable NASA to design and establish a high power (10 PW) high resolution (<10 cm), 24/7 availability radar system for (a) tracking and characterizing observations of Near Earth Objects (NEOs), (b) tracking, characterizing and determining the statistics of small-scale (≤10cm) orbital debris, (c) incorporating the capability into its space communication and navigation tracking stations for emergency spacecraft commanding in the Ka band era which NASA is entering, and (d) fielding capabilities of interest to other US government agencies. We present herein the results of our phased array uplink combining at near 7.17 and 8.3 GHz using widely separated antennas demonstrations, our moderately successful attempts to rescue the STEREO-B spacecraft (distance 2 astronomical units (185,000,000 miles), the first two attempts at imaging and ranging of near Earth asteroids, and progress in developing telescopes that are fully capable at radio and optical frequencies. And progress toward the implementation of our vision for going forward in implementing a high performance, low lifecycle cost multi-element radar array.

Millimetre Level Accuracy GNSS Positioning with the Blind Adaptive Beamforming Method in Interference Environments.

PubMed

Daneshmand, Saeed; Marathe, Thyagaraja; Lachapelle, Gérard

2016-10-31

The use of antenna arrays in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its superior capability to suppress both narrowband and wideband interference. However, the phase distortions resulting from array processing may limit the applicability of these methods for high precision applications using carrier phase based positioning techniques. This paper studies the phase distortions occurring with the adaptive blind beamforming method in which satellite angle of arrival (AoA) information is not employed in the optimization problem. To cater to non-stationary interference scenarios, the array weights of the adaptive beamformer are continuously updated. The effects of these continuous updates on the tracking parameters of a GNSS receiver are analyzed. The second part of this paper focuses on reducing the phase distortions during the blind beamforming process in order to allow the receiver to perform carrier phase based positioning by applying a constraint on the structure of the array configuration and by compensating the array uncertainties. Limitations of the previous methods are studied and a new method is proposed that keeps the simplicity of the blind beamformer structure and, at the same time, reduces tracking degradations while achieving millimetre level positioning accuracy in interference environments. To verify the applicability of the proposed method and analyze the degradations, array signals corresponding to the GPS L1 band are generated using a combination of hardware and software simulators. Furthermore, the amount of degradation and performance of the proposed method under different conditions are evaluated based on Monte Carlo simulations.

iTAG: Integrating a Cloud Based, Collaborative Animal Tracking Network into the GCOOS data portal in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Kirkpatrick, B. A.; Currier, R. D.; Simoniello, C.

2016-02-01

The tagging and tracking of aquatic animals using acoustic telemetry hardware has traditionally been the purview of individual researchers that specialize in single species. Concerns over data privacy and unauthorized use of receiver arrays have prevented the construction of large-scale, multi-species, multi-institution, multi-researcher collaborative acoustic arrays. We have developed a toolset to build the new portal using the Flask microframework, Python language, and Twitter bootstrap. Initial feedback has been overwhelmingly positive. The privacy policy has been praised for its granularity: principal investigators can choose between three levels of privacy for all data and hardware: Completely private - viewable only by the PI Visible to iTAG members Visible to the general public At the time of this writing iTAG is still in the beta stage, but the feedback received to date indicates that with the proper design and security features, and an iterative cycle of feedback from potential members, constructing a collaborative acoustic tracking network system is possible. Initial usage will be limited to the entry and searching for `orphan/mystery' tags, with the integration of historical array deployments and data following shortly thereafter. We have also been working with staff from the Ocean Tracking Network to allow for integration of the two systems. The database schema of iTAG is based on the marine metadata convention for acoustic telemetry. This should permit machine-to-machine data exchange between iTAG and OTN. The integration of animal telemetry data into the GCOOS portal will allow researchers to easily access the physiochemical oceanography data, thus allowing for a more in depth understanding of animal response and usage patterns.

Mineral resources of the Cabinet Mountains Wilderness, Lincoln and Sanders Counties, Montana

USGS Publications Warehouse

Lindsey, David A.; Wells, J.D.; Van Loenen, R. E.; Banister, D.P.; Welded, R.D.; Zilka, N.T.; Schmauch, S.W.

1978-01-01

This report describes the differential array, of seismometers recently installed at the Hollister, California, Municipal Airport. Such an array of relatively closely spaced seismometers has already been installed in El Centro and provided useful information for both engineering and seismological applications from the 1979 Imperial Valley earthquake. Differential ground motions, principally due to horizontally propagating surface waves, are important in determining the stresses in such extended structures as large mat foundations for nuclear power stations, dams, bridges and pipelines. Further, analyses of the records of the 1979 Imperial Valley earthquake from the differential array have demonstrated the utility of short-baseline array data in tracking the progress of the rupture wave front of an earthquake.

Advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) Small Spacecraft System

NASA Technical Reports Server (NTRS)

Lockett, Tiffany Russell; Martinez, Armando; Boyd, Darren; SanSouice, Michael; Farmer, Brandon; Schneider, Todd; Laue, Greg; Fabisinski, Leo; Johnson, Les; Carr, John A.

2015-01-01

This paper describes recent advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) currently being developed at NASA's Marshall Space Flight Center. The LISA-T array comprises a launch stowed, orbit deployed structure on which thin-film photovoltaic (PV) and antenna devices are embedded. The system provides significant electrical power generation at low weights, high stowage efficiency, and without the need for solar tracking. Leveraging high-volume terrestrial-market PVs also gives the potential for lower array costs. LISA-T is addressing the power starvation epidemic currently seen by many small-scale satellites while also enabling the application of deployable antenna arrays. Herein, an overview of the system and its applications are presented alongside sub-system development progress and environmental testing plans.

Advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) Small Spacecraft System

NASA Technical Reports Server (NTRS)

Russell, Tiffany; Martinez, Armando; Boyd, Darren; SanSoucie, Michael; Farmer, Brandon; Schneider, Todd; Fabisinski, Leo; Johnson, Les; Carr, John A.

2015-01-01

This paper describes recent advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) currently being developed at NASA's Marshall Space Flight Center. The LISA-T array comprises a launch stowed, orbit deployed structure on which thin-film photovoltaic (PV) and antenna devices are embedded. The system provides significant electrical power generation at low weights, high stowage efficiency, and without the need for solar tracking. Leveraging high-volume terrestrial-market PVs also gives the potential for lower array costs. LISA-T is addressing the power starvation epidemic currently seen by many small-scale satellites while also enabling the application of deployable antenna arrays. Herein, an overview of the system and its applications are presented alongside sub-system development progress and environmental testing plans/initial results.

Micromachined Radio Frequency (RF) Switches and Tunable Capacitors for Higher Performance Secure Communications Systems

DTIC Science & Technology

2003-04-01

range filters implemented with traditional semiconductor varactor diodes can require complex series-parallel circuit constructions to achieve sufficient...filter slice of the AIU and the varactor array modules are shown in Fig. 6.2. The complexity of the varactor array is clearly apparent. Further, it is...38 Fig. 6.2: Schematic of F-22 AIU UHF tracking filter, 2-pole filter, and varactor diode assembly

Performance Analysis for Lateral-Line-Inspired Sensor Arrays

DTIC Science & Technology

2011-06-01

found to affect numerous aspects of behavior including maneuvering in complex fluid environments, schooling, prey tracking, and environment mapping...190 5-29 Maps of the cost function for a reflected vortex model with an increasing array length but constant sensor spacing . The x at...length but constant sensor spacing . The x in each image denotes the true location of the vortex. The black lines correspond to level sets generated by the

Efficient Feature Extraction and Likelihood Fusion for Vehicle Tracking in Low Frame Rate Airborne Video

DTIC Science & Technology

2010-07-01

imagery, persistent sensor array I. Introduction New device fabrication technologies and heterogeneous embedded processors have led to the emergence of a...geometric occlusions between target and sensor , motion blur, urban scene complexity, and high data volumes. In practical terms the targets are small...distributed airborne narrow-field-of-view video sensor networks. Airborne camera arrays combined with com- putational photography techniques enable the

Phased-array laser radar: Concept and application

NASA Technical Reports Server (NTRS)

Kadrmas, K. A.

1973-01-01

The design and construction of a coaxial transmitter-receiver combination was investigated. Major emphasis was placed on simple permanent optical alignment, transmitter-receiver field of view matching, use of a pulsed gas laser as a transmitter maximum optical efficiency, complete digital control of data acquisition, and optical mount pointing and tracking. Also a means of expanding the coaxial transmitter-receiver concept to allow phased-array lidar, par-lidar was described.

Multiple-target tracking implementation in the ebCMOS camera system: the LUSIPHER prototype

NASA Astrophysics Data System (ADS)

Doan, Quang Tuyen; Barbier, Remi; Dominjon, Agnes; Cajgfinger, Thomas; Guerin, Cyrille

2012-06-01

The domain of the low light imaging systems progresses very fast, thanks to detection and electronic multiplication technology evolution, such as the emCCD (electron multiplying CCD) or the ebCMOS (electron bombarded CMOS). We present an ebCMOS camera system that is able to track every 2 ms more than 2000 targets with a mean number of photons per target lower than two. The point light sources (targets) are spots generated by a microlens array (Shack-Hartmann) used in adaptive optics. The Multiple-Target-Tracking designed and implemented on a rugged workstation is described. The results and the performances of the system on the identification and tracking are presented and discussed.

Soft-information flipping approach in multi-head multi-track BPMR systems

NASA Astrophysics Data System (ADS)

Warisarn, C.; Busyatras, W.; Myint, L. M. M.

2018-05-01

Inter-track interference is one of the most severe impairments in bit-patterned media recording system. This impairment can be effectively handled by a modulation code and a multi-head array jointly processing multiple tracks; however, such a modulation constraint has never been utilized to improve the soft-information. Therefore, this paper proposes the utilization of modulation codes with an encoded constraint defined by the criteria for soft-information flipping during a three-track data detection process. Moreover, we also investigate the optimal offset position of readheads to provide the most improvement in system performance. The simulation results indicate that the proposed systems with and without position jitter are significantly superior to uncoded systems.

Limits in point to point resolution of MOS based pixels detector arrays

NASA Astrophysics Data System (ADS)

Fourches, N.; Desforge, D.; Kebbiri, M.; Kumar, V.; Serruys, Y.; Gutierrez, G.; Leprêtre, F.; Jomard, F.

2018-01-01

In high energy physics point-to-point resolution is a key prerequisite for particle detector pixel arrays. Current and future experiments require the development of inner-detectors able to resolve the tracks of particles down to the micron range. Present-day technologies, although not fully implemented in actual detectors, can reach a 5-μm limit, this limit being based on statistical measurements, with a pixel-pitch in the 10 μm range. This paper is devoted to the evaluation of the building blocks for use in pixel arrays enabling accurate tracking of charged particles. Basing us on simulations we will make here a quantitative evaluation of the physical and technological limits in pixel size. Attempts to design small pixels based on SOI technology will be briefly recalled here. A design based on CMOS compatible technologies that allow a reduction of the pixel size below the micrometer is introduced here. Its physical principle relies on a buried carrier-localizing collecting gate. The fabrication process needed by this pixel design can be based on existing process steps used in silicon microelectronics. The pixel characteristics will be discussed as well as the design of pixel arrays. The existing bottlenecks and how to overcome them will be discussed in the light of recent ion implantation and material characterization experiments.

Genetic algorithm with maximum-minimum crossover (GA-MMC) applied in optimization of radiation pattern control of phased-array radars for rocket tracking systems.

PubMed

Silva, Leonardo W T; Barros, Vitor F; Silva, Sandro G

2014-08-18

In launching operations, Rocket Tracking Systems (RTS) process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs) with phased arrays (PAs). These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs), the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs). For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence.

Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) Applied in Optimization of Radiation Pattern Control of Phased-Array Radars for Rocket Tracking Systems

PubMed Central

Silva, Leonardo W. T.; Barros, Vitor F.; Silva, Sandro G.

2014-01-01

In launching operations, Rocket Tracking Systems (RTS) process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs) with phased arrays (PAs). These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs), the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs). For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence. PMID:25196013

High resolution three-dimensional robotic synthetic tracked aperture ultrasound imaging: feasibility study

NASA Astrophysics Data System (ADS)

Zhang, Haichong K.; Fang, Ting Yun; Finocchi, Rodolfo; Boctor, Emad M.

2017-03-01

Three dimensional (3D) ultrasound imaging is becoming a standard mode for medical ultrasound diagnoses. Conventional 3D ultrasound imaging is mostly scanned either by using a two dimensional matrix array or by motorizing a one dimensional array in the elevation direction. However, the former system is not widely assessable due to its cost, and the latter one has limited resolution and field-of-view in the elevation axis. Here, we propose a 3D ultrasound imaging system based on the synthetic tracked aperture approach, in which a robotic arm is used to provide accurate tracking and motion. While the ultrasound probe is moved by a robotic arm, each probe position is tracked and can be used to reconstruct a wider field-of-view as there are no physical barriers that restrict the elevational scanning. At the same time, synthetic aperture beamforming provides a better resolution in the elevation axis. To synthesize the elevational information, the single focal point is regarded as the virtual element, and forward and backward delay-andsum are applied to the radio-frequency (RF) data collected through the volume. The concept is experimentally validated using a general ultrasound phantom, and the elevational resolution improvement of 2.54 and 2.13 times was measured at the target depths of 20 mm and 110 mm, respectively.

Direct Data Distribution From Low-Earth Orbit

NASA Technical Reports Server (NTRS)

Budinger, James M.; Fujikawa, Gene; Kunath, Richard R.; Nguyen, Nam T.; Romanofsky, Robert R.; Spence, Rodney L.

1997-01-01

NASA Lewis Research Center (LeRC) is developing the space and ground segment technologies necessary to demonstrate a direct data distribution (1)3) system for use in space-to-ground communication links from spacecraft in low-Earth orbit (LEO) to strategically located tracking ground terminals. The key space segment technologies include a K-band (19 GHz) MMIC-based transmit phased array antenna, and a multichannel bandwidth- and power-efficient digital encoder/modulate with an aggregate data rate of 622 Mb/s. Along with small (1.8 meter), low-cost tracking terminals on the ground, the D3 system enables affordable distribution of data to the end user or archive facility through interoperability with commercial terrestrial telecommunications networks. The D3 system is applicable to both government and commercial science and communications spacecraft in LEO. The features and benefits of the D3 system concept are described. Starting with typical orbital characteristics, a set of baseline requirements for representative applications is developed, including requirements for onboard storage and tracking terminals, and sample link budgets are presented. Characteristics of the transmit array antenna and digital encoder/modulator are described. The architecture and components of the tracking terminal are described, including technologies for the next generation terminal. Candidate flights of opportunity for risk mitigation and space demonstration of the D3 features are identified.

Underwater behavior of sperm whales off Kaikoura, New Zealand, as revealed by a three-dimensional hydrophone array.

PubMed

Miller, Brian; Dawson, Stephen; Vennell, Ross

2013-10-01

Observations are presented of the vocal behavior and three dimensional (3D) underwater movements of sperm whales measured with a passive acoustic array off the coast of Kaikoura, New Zealand. Visual observations and vocal behaviors of whales were used to divide dive tracks into different phases, and depths and movements of whales are reported for each of these phases. Diving depths and movement information from 75 3D tracks of whales in Kaikoura are compared to one and two dimensional tracks of whales studied in other oceans. While diving, whales in Kaikoura had a mean swimming speed of 1.57 m/s, and, on average, dived to a depth of 427 m (SD = 117 m), spending most of their time at depths between 300 and 600 m. Creak vocalizations, assumed to be the prey capture phase of echolocation, occurred throughout the water column from sea surface to sea floor, but most occurred at depths of 400-550 m. Three dimensional measurement of tracking revealed several different "foraging" strategies, including active chasing of prey, lining up slow-moving or unsuspecting prey, and foraging on demersal or benthic prey. These movements provide the first 3D descriptions underwater behavior of whales at Kaikoura.

Operation's Concept for Array-Based Deep Space Network

NASA Technical Reports Server (NTRS)

Bagri, Durgadas S.; Statman, Joseph I.; Gatti, Mark S.

2005-01-01

The Array-based Deep Space Network (DSNArray) will be a part of more than 10(exp 3) times increase in the downlink/telemetry capability of the Deep space Network (DSN). The key function of the DSN-Array is to provide cost-effective, robust Telemetry, Tracking and Command (TT&C) services to the space missions of NASA and its international partners. It provides an expanded approach to the use of an array-based system. Instead of using the array as an element in the existing DSN, relying to a large extent on the DSN infrastructure, we explore a broader departure from the current DSN, using fewer elements of the existing DSN, and establishing a more modern Concept of Operations. This paper gives architecture of DSN-Array and its operation's philosophy. It also describes customer's view of operations, operations management and logistics - including maintenance philosophy, anomaly analysis and reporting.

An Overview of GRETINA and its Physics Program

NASA Astrophysics Data System (ADS)

Macchiavelli, Augusto

2016-09-01

GRETINA, a first implementation of a gamma-ray tracking array, combines unparalleled position resolution, large Ge efficiency, and good P/T to provide a powerful tool for in-beam gamma-ray spectroscopy. The commissioning in 2012 demonstrated the technical feasibility and unique capabilities of a gamma-ray tracking array, and successful physics campaigns have followed at NSCL/MSU(2013/14) and ATLAS/ANL (2014/15). New and exciting physic results have been shown in a broad range of topics, clearly confirming the expectations of excellent performance in both high- and Coulomb barrier-energy environments, and in multiple configurations. GRETINA is again operating at NSCL for a second campaign coupled to the S800 spectrometer. Following a brief status report of the array, I will present some selected highlights from the science campaigns, complementing the latest results to be discussed in this mini-symposium. Future plans, with an emphasis on the development and construction of the full 4 π GRETA, will also be discussed. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-05CH11231.

A Database of Tornado Events as Perceived by the USArray Transportable Array Network

NASA Astrophysics Data System (ADS)

Tytell, J. E.; Vernon, F.; Reyes, J. C.

2015-12-01

Over the course of the deployment of Earthscope's USArray Transportable Array (TA) network there have numerous tornado events that have occurred within the changing footprint of its network. The Array Network Facility based in San Diego, California, has compiled a database of these tornado events based on data provided by the NOAA Storm Prediction Center (SPC). The SPC data itself consists of parameters such as start-end point track data for each event, maximum EF intensities, and maximum track widths. Our database is Antelope driven and combines these data from the SPC with detailed station information from the TA network. We are now able to list all available TA stations during any specific tornado event date and also provide a single calculated "nearest" TA station per individual tornado event. We aim to provide this database as a starting resource for those with an interest in investigating tornado signatures within surface pressure and seismic response data. On a larger scale, the database may be of particular interest to the infrasound research community

Long range guided wave defect monitoring in rail track

NASA Astrophysics Data System (ADS)

Loveday, Philip W.; Long, Craig S.

2014-02-01

A guided wave ultrasound system was previously developed for monitoring rail track used on heavy duty freight lines. This system operates by transmitting guided waves between permanently installed transmit and receive transducers spaced approximately 1km apart. The system has been proven to reliably detect rail breaks without false alarms. While cracks are sometimes detected there is a trade - off between detecting cracks and the possibility of false alarms. Adding a pulse-echo mode of operation to the system could provide increased functionality by detecting, locating and possibly monitoring cracks. This would require an array of transducers to control the direction and mode of propagation and it would be necessary to detect cracks up to a range of approximately 500 m in either direction along the rail. A four transducer array was designed and full matrix capture was used for field measurements. Post processing of the signals showed that a thermite weld could be detected at a range of 790m from the transducer array. It was concluded that the required range can be achieved in new rail while it would be extremely difficult in very old rail.

Gimbal Control Algorithms for the Global Precipitation Measurement Core Observatory

NASA Technical Reports Server (NTRS)

Welter, Gary L.; Liu, Kuo Chia; Blaurock, Carl

2012-01-01

There are two gimbaled systems on the Global Precipitation Measurement Core Observatory: two single-degree-of-freedom solar arrays (SAs) and one two-degree-of-freedom high gain antenna (HGA). The guidance, navigation, and control analysis team was presented with the following challenges regarding SA orientation control during periods of normal mission science: (1) maximize solar flux on the SAs during orbit day, subject to battery charging limits, (2) minimize atmospheric drag during orbit night to reduce frequency of orbit maintenance thruster usage, (3) minimize atmospheric drag during orbits for which solar flux is nearly independent of SA orientation, and (4) keep array-induced spacecraft attitude disturbances within allocated tolerances. The team was presented with the following challenges regarding HGA control during mission science periods: (1) while tracking a ground-selected Tracking Data and Relay Satellite (TDRS), keep HGA control error below about 4', (2) keep array-induced spacecraft attitude disturbances small, and (3) minimize transition time between TDRSs subject to constraints imposed by item 2. This paper describes the control algorithms developed to achieve these goals and certain analysis done as part of that work.

Micromachined three-dimensional electrode arrays for transcutaneous nerve tracking

NASA Astrophysics Data System (ADS)

Rajaraman, Swaminathan; Bragg, Julian A.; Ross, James D.; Allen, Mark G.

2011-08-01

We report the development of metal transfer micromolded (MTM) three-dimensional microelectrode arrays (3D MEAs) for a transcutaneous nerve tracking application. The measurements of electrode-skin-electrode impedance (ESEI), electromyography (EMG) and nerve conduction utilizing these minimally invasive 3D MEAs are demonstrated in this paper. The 3D MEAs used in these measurements consist of a metalized micro-tower array that can penetrate the outer layers of the skin in a painless fashion and are fabricated using MTM technology. Two techniques, an inclined UV lithography approach and a double-side exposure of thick negative tone resist, have been developed to fabricate the 3D MEA master structure. The MEAs themselves are fabricated from the master structure utilizing micromolding techniques. Metal patterns are transferred during the micromolding process, thereby ensuring reduced process steps compared to traditional silicon-based approaches. These 3D MEAs have been packaged utilizing biocompatible Kapton® substrates. ESEI measurements have been carried out on test human subjects with standard commercial wet electrodes as a reference. The 3D MEAs demonstrate an order of magnitude lower ESEI (normalized to area) compared to wet electrodes for an area that is 12.56 times smaller. This compares well with other demonstrated approaches in literature. For a nerve tracking demonstration, we have chosen EMG and nerve conduction measurements on test human subjects. The 3D MEAs show 100% improvement in signal power and SNR/√area as compared to standard electrodes. They also demonstrate larger amplitude signals and faster rise times during nerve conduction measurements. We believe that this microfabrication and packaging approach scales well to large-area, high-density arrays required for applications like nerve tracking. This development will increase the stimulation and recording fidelity of skin surface electrodes, while increasing their spatial resolution by an order of magnitude or more. Although biopotential electrode systems are not without their challenges, the non-invasive access to neural information, along with the potential for automation with associated electronic and software development, is precisely what makes this technology an excellent candidate for the next generation in diagnostic, therapeutic, and prosthetic devices.

Tracking Solar Type II Bursts with Space Based Radio Interferometers

NASA Astrophysics Data System (ADS)

Hegedus, Alexander M.; Kasper, Justin C.; Manchester, Ward B.

2018-06-01

The Earth’s Ionosphere limits radio measurements on its surface, blocking out any radiation below 10 MHz. Valuable insight into many astrophysical processes could be gained by having a radio interferometer in space to image the low frequency window for the first time. One application is observing type II bursts tracking solar energetic particle acceleration in Coronal Mass Ejections (CMEs). In this work we create a simulated data processing pipeline for several space based radio interferometer (SBRI) concepts and evaluate their performance in the task of localizing these type II bursts.Traditional radio astronomy software is hard coded to assume an Earth based array. To circumvent this, we manually calculate the antenna separations and insert them along with the simulated visibilities into a CASA MS file for analysis. To create the realest possible virtual input data, we take a 2-temperature MHD simulation of a CME event, superimpose realistic radio emission models from the CME-driven shock front, and propagate the signal through simulated SBRIs. We consider both probabilistic emission models derived from plasma parameters correlated with type II bursts, and analytical emission models using plasma emission wave interaction theory.One proposed SBRI is the pathfinder mission SunRISE, a 6 CubeSat interferometer to circle the Earth in a GEO graveyard orbit. We test simulated trajectories of SunRISE and image what the array recovers, comparing it to the virtual input. An interferometer on the lunar surface would be a stable alternative that avoids noise sources that affect orbiting arrays, namely the phase noise from positional uncertainty and atmospheric 10s-100s kHz noise. Using Digital Elevation Models from laser altimeter data, we test different sets of locations on the lunar surface to find near optimal configurations for tracking type II bursts far from the sun. Custom software is used to model the response of different array configurations over the lunar year, combining ephemerides of the sun and moon to correlate the virtual data. We analyze the pros and cons of all approaches and offer recommendations for SRBIs that track type II bursts.

Relative potentials of concentrating and two-axis tracking flat-plate photovoltaic arrays for central-station applications

NASA Technical Reports Server (NTRS)

Borden, C. S.; Schwartz, D. L.

1984-01-01

The purpose of this study is to assess the relative economic potentials of concenrating and two-axis tracking flat-plate photovoltaic arrays for central-station applications in the mid-1990's. Specific objectives of this study are to provide information on concentrator photovoltaic collector probabilistic price and efficiency levels to illustrate critical areas of R&D for concentrator cells and collectors, and to compare concentrator and flat-plate PV price and efficiency alternatives for several locations, based on their implied costs of energy. To deal with the uncertainties surrounding research and development activities in general, a probabilistic assessment of commercially achievable concentrator photovoltaic collector efficiencies and prices (at the factory loading dock) is performed. The results of this projection of concentrator photovoltaic technology are then compared with a previous flat-plate module price analysis (performed early in 1983). To focus this analysis on specific collector alternatives and their implied energy costs for different locations, similar two-axis tracking designs are assumed for both concentrator and flat-plate options.

Improved charge injection device and a focal plane interface electronics board for stellar tracking

NASA Technical Reports Server (NTRS)

Michon, G. J.; Burke, H. K.

1984-01-01

An improved Charge Injection Device (CID) stellar tracking sensor and an operating sensor in a control/readout electronics board were developed. The sensor consists of a shift register scanned, 256x256 CID array organized for readout of 4x4 subarrays. The 4x4 subarrays can be positioned anywhere within the 256x256 array with a 2 pixel resolution. This allows continuous tracking of a number of stars simultaneously since nine pixels (3x3) centered on any star can always be read out. Organization and operation of this sensor and the improvements in design and semiconductor processing are described. A hermetic package incorporating an internal thermoelectric cooler assembled using low temperature solders was developed. The electronics board, which contains the sensor drivers, amplifiers, sample hold circuits, multiplexer, analog to digital converter, and the sensor temperature control circuits, is also described. Packaged sensors were evaluated for readout efficiency, spectral quantum efficiency, temporal noise, fixed pattern noise, and dark current. Eight sensors along with two tracker electronics boards were completed, evaluated, and delivered.

Dynamic kirigami structures for integrated solar tracking.

PubMed

Lamoureux, Aaron; Lee, Kyusang; Shlian, Matthew; Forrest, Stephen R; Shtein, Max

2015-09-08

Optical tracking is often combined with conventional flat panel solar cells to maximize electrical power generation over the course of a day. However, conventional trackers are complex and often require costly and cumbersome structural components to support system weight. Here we use kirigami (the art of paper cutting) to realize novel solar cells where tracking is integral to the structure at the substrate level. Specifically, an elegant cut pattern is made in thin-film gallium arsenide solar cells, which are then stretched to produce an array of tilted surface elements which can be controlled to within ±1°. We analyze the combined optical and mechanical properties of the tracking system, and demonstrate a mechanically robust system with optical tracking efficiencies matching conventional trackers. This design suggests a pathway towards enabling new applications for solar tracking, as well as inspiring a broader range of optoelectronic and mechanical devices.

Dynamic kirigami structures for integrated solar tracking

PubMed Central

Lamoureux, Aaron; Lee, Kyusang; Shlian, Matthew; Forrest, Stephen R.; Shtein, Max

2015-01-01

Optical tracking is often combined with conventional flat panel solar cells to maximize electrical power generation over the course of a day. However, conventional trackers are complex and often require costly and cumbersome structural components to support system weight. Here we use kirigami (the art of paper cutting) to realize novel solar cells where tracking is integral to the structure at the substrate level. Specifically, an elegant cut pattern is made in thin-film gallium arsenide solar cells, which are then stretched to produce an array of tilted surface elements which can be controlled to within ±1°. We analyze the combined optical and mechanical properties of the tracking system, and demonstrate a mechanically robust system with optical tracking efficiencies matching conventional trackers. This design suggests a pathway towards enabling new applications for solar tracking, as well as inspiring a broader range of optoelectronic and mechanical devices. PMID:26348820

High Rate User Ka-Band Phased Array Antenna Test Results

NASA Technical Reports Server (NTRS)

Caroglanian, Armen; Perko, Kenneth; Seufert, Steve; Dod, Tom; Warshowsky, Jay; Day, John H. (Technical Monitor)

2001-01-01

The High Rate User Phased Array Antenna (HRUPAA) is a Ka-Band planar phased array designed by the Harris Corporation for the NASA Goddard Space Flight Center. The HRUPAA permits a satellite to downlink data either to a ground station or through the Tracking and Data Relay Satellite System (TDRSS). The HRUPAA is scanned electronically by ground station / user satellite command over a 120 degree cone angle. The phased array has the advantage of not imparting attitude disturbances to the user spacecraft. The 288-element transmit-only array has distributed RF amplifiers integrated behind each of the printed patch antenna elements. The array has 33 dBW EIRP and is left-hand circularly polarized. An engineering model of a partially populated array has been developed and delivered to NASA Goddard Space Flight Center. This report deals with the testing of the engineering model at the Goddard Antenna Range near-field and compact range facilities. The antenna specifications are described first, followed by the test plan and test results.

Radial microstrip slotline feed network for circular mobile communications array

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Kelly, Eron S.; Lee, Richard Q.; Taub, Susan R.

1994-01-01

In mobile and satellite communications there is a need for low cost and low profile antennas which have a toroidal pattern. Antennas that have been developed for mobile communications include a L-Band electronically steered stripline phased array, a Ka-Band mechanically steered elliptical reflector antenna and a Ka-Band printed dipole. In addition, a L-Band mechanically steered microstrip array, a L-Band microstrip phased array tracking antenna for mounting on a car roof and an X-Band radial line slotted waveguide antenna have been demonstrated. In the above electronically scanned printed arrays, the individual element radiates normally to the plane of the array and hence require a phase shifter to scan the beam towards the horizon. Scanning in the azimuth is by mechanical or electronic steering. An alternate approach is to mount microstrip patch radiators on the surface of a cone to achieve the required elevation angle. The array then scans in the azimuth by beam switching.

Solar maximum: Solar array degradation

NASA Technical Reports Server (NTRS)

Miller, T.

1985-01-01

The 5-year in-orbit power degradation of the silicon solar array aboard the Solar Maximum Satellite was evaluated. This was the first spacecraft to use Teflon R FEP as a coverglass adhesive, thus avoiding the necessity of an ultraviolet filter. The peak power tracking mode of the power regulator unit was employed to ensure consistent maximum power comparisons. Telemetry was normalized to account for the effects of illumination intensity, charged particle irradiation dosage, and solar array temperature. Reference conditions of 1.0 solar constant at air mass zero and 301 K (28 C) were used as a basis for normalization. Beginning-of-life array power was 2230 watts. Currently, the array output is 1830 watts. This corresponds to a 16 percent loss in array performance over 5 years. Comparison of Solar Maximum Telemetry and predicted power levels indicate that array output is 2 percent less than predictions based on an annual 1.0 MeV equivalent election fluence of 2.34 x ten to the 13th power square centimeters space environment.

The performance of the γ-ray tracking array GRETINA for γ-ray spectroscopy with fast beams of rare isotopes

DOE PAGES

Weisshaar, D.; Bazin, D.; Bender, P. C.; ...

2016-12-03

The gamma-ray tracking array GRETINA was coupled to the S800 magnetic spectrometer for spectroscopy with fast beams of rare isotopes at the National Superconducting Cyclotron Laboratory on the campus of Michigan State University. We describe the technical details of this powerful setup and report on GRETINA's performance achieved with source and in-beam measurements. The gamma-ray multiplicity encountered in experiments with fast beams is usually low, allowing for a simplified and efficient treatment of the data in the gamma-ray analysis in terms of Doppler reconstruction and spectral quality. Finally, the results reported in this work were obtained from GRETINA consisting ofmore » 8 detector modules hosting four high-purity germanium crystals each. Currently, GRETINA consists of 10 detector modules.« less

Use of Very Long Baseline Array Interferometric Data for Spacecraft Navigation

NASA Technical Reports Server (NTRS)

Martin-Mur, Tomas J.; Antreasian, P.; Border, J.; Benson, J.; Dhawan, V.; Fomalont, E.; Graat, E.; Jacobson, R.; Lanyi, G.; McElrath, T.;

Development of an artificial sensor for hydrodynamic detection inspired by a seal's whisker array.

PubMed

Eberhardt, William C; Wakefield, Brendan F; Murphy, Christin T; Casey, Caroline; Shakhsheer, Yousef; Calhoun, Benton H; Reichmuth, Colleen

2016-08-31

Nature has shaped effective biological sensory systems to receive complex stimuli generated by organisms moving through water. Similar abilities have not yet been fully developed in artificial systems for underwater detection and monitoring, but such technology would enable valuable applications for military, commercial, and scientific use. We set out to design a fluid motion sensor array inspired by the searching performance of seals, which use their whiskers to find and follow underwater wakes. This sensor prototype, called the Wake Information Detection and Tracking System (WIDTS), features multiple whisker-like elements that respond to hydrodynamic disturbances encountered while moving through water. To develop and test this system, we trained a captive harbor seal (Phoca vitulina) to wear a blindfold while tracking a remote-controlled, propeller-driven submarine. After mastering the tracking task, the seal learned to carry the WIDTS adjacent to its own vibrissal array during active pursuit of the target. Data from the WIDTS sensors describe changes in the deflection angles of the whisker elements as they pass through the hydrodynamic trail left by the submarine. Video performance data show that these detections coincide temporally with WIDTS-wake intersections. Deployment of the sensors on an actively searching seal allowed for the direct comparison of our instrument to the ability of the biological sensory system in a proof-of-concept demonstration. The creation of the WIDTS provides a foundation for instrument development in the field of biomimetic fluid sensor technology.

Method and apparatus for acquisition and tracking of light sources in a transient event rich environment

NASA Technical Reports Server (NTRS)

Bolin, Kenneth (Inventor); Flynn, David (Inventor); Fowski, Walter (Inventor); Miklus, Kenneth (Inventor); Kissh, Frank (Inventor); Abreu, Rene (Inventor)

1993-01-01

A method and apparatus for tracking a light source in a transient event rich environment locks on to a light source incident on a field-of-view 1 of a charge-coupled-device (CCD) array 6, validates the permanence of said light source and transmits data relating to the brilliance and location of said light source if said light source is determined to be permanent.

Instrumentation Techniques for Tracking Low-Flying Vehicles

DTIC Science & Technology

1975-07-15

feet long (Appendix C). The weight budget could be 1000 pounds. The equip- ment in the pod would include (1) range and range rate measuring devices, (2...advantages would probably outweigh the drawback of beam spreading and loss of resolution as the beam is deflected from normal to the array plane. However...necessitates minimizing size and weight of the airborne equipment. .It is suggested that the data generated by the airborne tracking system be

Bayesian source tracking via focalization and marginalization in an uncertain Mediterranean Sea environment.

PubMed

Dosso, Stan E; Wilmut, Michael J; Nielsen, Peter L

2010-07-01

This paper applies Bayesian source tracking in an uncertain environment to Mediterranean Sea data, and investigates the resulting tracks and track uncertainties as a function of data information content (number of data time-segments, number of frequencies, and signal-to-noise ratio) and of prior information (environmental uncertainties and source-velocity constraints). To track low-level sources, acoustic data recorded for multiple time segments (corresponding to multiple source positions along the track) are inverted simultaneously. Environmental uncertainty is addressed by including unknown water-column and seabed properties as nuisance parameters in an augmented inversion. Two approaches are considered: Focalization-tracking maximizes the posterior probability density (PPD) over the unknown source and environmental parameters. Marginalization-tracking integrates the PPD over environmental parameters to obtain a sequence of joint marginal probability distributions over source coordinates, from which the most-probable track and track uncertainties can be extracted. Both approaches apply track constraints on the maximum allowable vertical and radial source velocity. The two approaches are applied for towed-source acoustic data recorded at a vertical line array at a shallow-water test site in the Mediterranean Sea where previous geoacoustic studies have been carried out.

SLR tracking of GPS-35

NASA Technical Reports Server (NTRS)

Pavlis, Erricos C.

1994-01-01

An experiment was designed to launch a corner cube retroreflector array on one of the Global Positioning Satellites (GPS). The launch on Aug. 31, 1993 ushered in the era of SLR tracking of GPS spacecraft. Once the space operations group finished the check-out procedures for the new satellite, the agreed upon SLR sites were allowed to track it. The first site to acquire GPS-35 was the Russian system at Maidanak and closely after the MLRS system at McDonald Observatory, Texas. The laser tracking network is currently tracking the GPS spacecraft known as GPS-35 or PRN 5 with great success. From the NASA side there are five stations that contribute data regularly and nearly as many from the international partners. Upcoming modifications to the ground receivers will allow for a further increase in the tracking capabilities of several additional sites and add some desperately needed southern hemisphere tracking. We are analyzing the data and are comparing SLR-derived orbits to those determined on the basis of GPS radiometric data.

Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

2013-01-26

This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array ofmore » newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high-resolution (fine scale, very near-field) fluid/structure interaction simulations of buoy motions, as well as array-scale, phase-resolving wave scattering simulations. These modeling efforts will utilize state-of-the-art research quality models, which have not yet been brought to bear on this complex problem of large array wave/structure interaction problem.« less

Controllability of Large SEP for Earth Orbit Raising

NASA Technical Reports Server (NTRS)

Woodcock, Gordon

2004-01-01

A six-degree-of-freedom (6DOF) simulation was constructed and exercised for a large solar electric propulsion (SEP) vehicle operating in low Earth orbit Nominal power was 500 kWe, with the large array sizes implied. Controllability issues, including gravity gradient, roll maneuvering for Sun tracking, and flexible arrays, and flight control methods, were investigated. Initial findings are that a SEP vehicle of this size is controllable and could be used for orbit raising of heavy payloads.

Compressive Channel Estimation and Tracking for Large Arrays in mm Wave Picocells

DTIC Science & Technology

2014-01-01

abling sophisticated adaptation, including frequency-selective spatiotemporal processing (e.g., per subcarrier beamforming in OFDM systems). This approach...subarrays are certainly required for more advanced functionalities such as multiuser MIMO [17], spatial multiplexing [18], [19], [20], [21], [22], and...case, a regu- larly spaced 2D array), an estimate of the N2t,1D × N2r,1D MIMO channel matrix H can be efficiently arrived at by estimating the spatial

Lighting Condition Analysis for Mars' Moon Phobos

NASA Technical Reports Server (NTRS)

Li, Zu Qun; de Carufel, Guy; Crues, Edwin Z.; Bielski, Paul

2016-01-01

This study used high fidelity computer simulation to investigate the lighting conditions, specifically the solar radiation flux over the surface, on Phobos. Ephemeris data from the Jet Propulsion Laboratory (JPL) DE405 model was used to model the state of the Sun, Earth, Moon, and Mars. An occultation model was developed to simulate Phobos' self-shadowing and its solar eclipses by Mars. The propagated Phobos state was compared with data from JPL's Horizon system to ensure the accuracy of the result. Results for Phobos lighting conditions over one Martian year are presented, which include the duration of solar eclipses, average solar radiation intensity, surface exposure time, available energy per unit area for sun tracking arrays, and available energy per unit area for fixed arrays (constrained by incident angle). The results show that: Phobos' solar eclipse time varies throughout the Martian year, with longer eclipse durations during the Martian spring and fall seasons and no eclipses during the Martian summer and winter seasons; solar radiation intensity is close to minimum at the summer solstice and close to maximum at the winter solstice; exposure time per orbit is relatively constant over the surface during the spring and fall but varies with latitude during the summer and winter; and Sun tracking solar arrays generate more energy than a fixed solar array. A usage example of the result is also present in this paper to demonstrate the utility.

SU-F-J-142: Proposed Method to Broaden Inclusion Potential of Patients Able to Use the Calypso Tracking System in Prostate Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fiedler, D; Kuo, H; Bodner, W

2016-06-15

Purpose: To introduce a non-standard method of patient setup, using BellyBoard immobilization, to better utilize the localization and tracking potential of an RF-beacon system with EBRT for prostate cancer. Methods: An RF-beacon phantom was imaged using a wide bore CT scanner, both in a standard level position and with a known rotation (4° pitch and 7.5° yaw). A commercial treatment planning system (TPS) was used to determine positional coordinates of each beacon, and the centroid of the three beacons for both setups. For each setup at the Linac, kV AP and Rt Lateral images were obtained. A full characterization ofmore » the RF-beacon system in clinical mode was completed for various beacons’ array-to-centroid distances, which includes vertical, lateral, and longitudinal offset data, as well as pitch and yaw offset measurements for the tilted phantom. For the single patient who has been setup using the proposed BellyBoard method, a supine simulation was first obtained. When abdominal protrusion was found to be exceeding the limits of the RF-Beacon system through distance-based analysis in the TPS, the patient is re-simulated prone with the BellyBoard. Array to centroid distance is measured again in the TPS, and if found to be within the localization or tracking region it is applied. Results: Characterization of limitations for the RF-beacon system in clinical mode showed acceptable consistency of offset determination for phantom setup accuracy. The nonstandard patient setup method reduced the beacons’ centroid-to-array distance by 8.32cm, from 25.13cm to 16.81cm; completely out of tracking range (greater than 20cm) to within setup tracking range (less than 20cm). Conclusion: Using the RF-beacon system in combination with this novel patient setup can allow patients who would otherwise not be candidates for beacon enhanced EBRT to now be able to benefit from the reduced PTV margins of this treatment method.« less

Improved receiver arrays and optimized parallel imaging accelerations applied to time-resolved 3D fluoroscopically tracked peripheral runoff CE-MRA.

PubMed

Weavers, Paul T; Borisch, Eric A; Hulshizer, Tom C; Rossman, Phillip J; Young, Phillip M; Johnson, Casey P; McKay, Jessica; Cline, Christopher C; Riederer, Stephen J

2016-04-01

Three-station stepping-table time-resolved 3D contrast-enhanced magnetic resonance angiography has conflicting demands in the need to limit acquisition time in proximal stations to match the speed of the advancing contrast bolus and in the distal-most station to avoid venous contamination while still providing clinically useful spatial resolution. This work describes improved receiver coil arrays which address this issue by allowing increased acceleration factors, providing increased spatial resolution per unit time. Receiver coil arrays were constructed for each station (pelvis, thigh, calf) and then integrated into a 48-element array for three-station peripheral CE-MRA. Coil element sizes and array configurations for these three stations were designed to improve SENSE-type parallel imaging taking advantage of an increase in coil count for all stations versus the previous 32 channel capability. At each station either acceleration apportionment or optimal CAIPIRINHA selection was used to choose the optimum acceleration parameters for each subject. Results were evaluated in both single- and multi-station studies. Single-station studies showed that SENSE acceleration in the thigh station could be readily increased from R=8 to R=10, allowing reduction of the frame time from 2.5 to 2.1 s to better image the typically rapidly advancing bolus at this station. Similarly, the improved coil array for the calf station permitted acceleration increase from R=8 to R=12, providing a 4.0 vs. 5.2 s frame time. Results in three-station studies suggest an improved ability to track the contrast bolus in peripheral CE-MRA. Modified receiver coil arrays and individualized parameter optimization have been used to provide improved acceleration at all stations in multi-station peripheral CE-MRA and provide high spatial resolution with frame times as short as 2.1 s. Copyright © 2015 Elsevier Inc. All rights reserved.

Evaluating De-centralised and Distributional Options for the Distributed Electronic Warfare Situation Awareness and Response Test Bed

DTIC Science & Technology

2013-12-01

effectors (deployed on ground based or aerial platforms) to detect , identify, locate, track or suppress stationary or slow moving surface based RF...ground based or aerial platforms) to detect , identify, locate, track or suppress stationary or slow moving surface based RF emitting targets. In the...Electronic Support EO Electro-Optic FPGAs Field Programmable Gate Arrays IR Infra-red LADAR Laser Detection and Ranging OSX Mac OS X; the apple

Propulsion and Levitation with a Large Electrodynamic Wheel

NASA Astrophysics Data System (ADS)

Gaul, Nathan; Lane, Hannah

We constructed an electrodynamic wheel using a motorized bicycle wheel with a radius of 12 inches and 36 one-inch cube magnets attached to the rim of the wheel. The radial magnetic field on the outside of the wheel was maximized by arranging the magnets into a series of Halbach arrays which amplify the field on one side of the array and reduce it on the other side. Rotating the wheel produces a rapidly oscillating magnetic field. When a conductive metal ``track'' is placed in this area of strong magnetic flux, eddy currents are produced in the track. These eddy currents create magnetic fields that interact with the magnetic fields from the electrodynamic wheel. The interaction of the magnetic fields produces lift and drag forces on the track which were measured with force gauges. Measurements were taken at a variety of wheel speeds, and the results were compared to the theoretical prediction that there should be a linear relationship between the lift and drag forces with increasing wheel speed. Partial levitation was achieved with the current electrodynamic wheel. In the future, the wheel will be upgraded to include 72 magnets rather than 36 magnets. This will double the frequency at which the magnetic field oscillates, increasing the magnetic flux. Electrodynamic wheels have applications to the transportation industry, since multiple electrodynamic wheels could be used on a vehicle to produce a lift and propulsion force over a conductive track.

Inkjet printing and electrical characterisation of DNA-templated cadmium sulphide nanowires

NASA Astrophysics Data System (ADS)

Nurdillayeva, R. N.; Oshido, A. B.; Bamford, T. A.; El-Zubir, O.; Houlton, A.; Hedley, J.; Pike, A. R.; Horrocks, B. R.

2018-04-01

Cadmium sulphide can be templated on λ-DNA molecules to form an aqueous dispersion of CdS/λ-DNA nanowires. Subsequent addition of ethylene glycol to 50% v/v is sufficient to formulate an ink suitable for printing using piezoelectric drop-on-demand technology. Printed droplet arrays show a coffee-ring morphology of individual deposits by fluorescence and Raman microscopy, but upon increasing the number of layers of printed material by repeated printing over each droplet, the dry deposit approaches closer to a disc shape. It is also possible to print parallel tracks by reducing the droplet separation in the array until neighbouring droplets overlap before they dry. The droplets coalesce to form a strip of width roughly equal to the diameter of the droplets. Evaporation-driven capillary flow sends the nanowires to the edges of the strip and when dry they form parallel tracks of CdS/λ-DNA nanowire bundles. Both droplets and tracks were printed onto Pt-on-glass interdigitated microelectrodes (10 μm width, 10 μm gap). The current-voltage characteristics of these two-terminal devices were approximately ohmic, but with some hysteresis. The conductance increased with temperature as a simple activated process with activation energies of 0.57 ± 0.02 eV (tracks) and 0.39 ± 0.02 eV (droplets). The impedance spectra of the printed films were consistent with hopping between CdS grains.

Photon caliper to achieve submillimeter positioning accuracy

NASA Astrophysics Data System (ADS)

Gallagher, Kyle J.; Wong, Jennifer; Zhang, Junan

2017-09-01

The purpose of this study was to demonstrate the feasibility of using a commercial two-dimensional (2D) detector array with an inherent detector spacing of 5 mm to achieve submillimeter accuracy in localizing the radiation isocenter. This was accomplished by delivering the Vernier ‘dose’ caliper to a 2D detector array where the nominal scale was the 2D detector array and the non-nominal Vernier scale was the radiation dose strips produced by the high-definition (HD) multileaf collimators (MLCs) of the linear accelerator. Because the HD MLC sequence was similar to the picket fence test, we called this procedure the Vernier picket fence (VPF) test. We confirmed the accuracy of the VPF test by offsetting the HD MLC bank by known increments and comparing the known offset with the VPF test result. The VPF test was able to determine the known offset within 0.02 mm. We also cross-validated the accuracy of the VPF test in an evaluation of couch hysteresis. This was done by using both the VPF test and the ExacTrac optical tracking system to evaluate the couch position. We showed that the VPF test was in agreement with the ExacTrac optical tracking system within a root-mean-square value of 0.07 mm for both the lateral and longitudinal directions. In conclusion, we demonstrated the VPF test can determine the offset between a 2D detector array and the radiation isocenter with submillimeter accuracy. Until now, no method to locate the radiation isocenter using a 2D detector array has been able to achieve such accuracy.

The Extensive Air Shower Experiment Kascade-Grande

NASA Astrophysics Data System (ADS)

Kang, Donghwa; Apel, W. D.; Arteaga, J. C.; Badea, F.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kickelbick, D.; Klages, H. O.; Kolotaev, Y.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schatz, G.; Schieler, H.; Schröder, F.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

The extensive air shower experiment KASCADE-Grande (KArlsruhe Shower Core and Array DEtector and Grande array) is located on site of the Forschungszentrum Karlsruhe in Germany. The original KASCADE experiment consisted of a densely packed scintillator array with unshielded and shielded detectors for the measurement of the electromagnetic and muonic shower component independently, as well as muon tracking devices and a hadron calorimeter. The Grande array as an extension of KASCADE consists of 37 scintillation detector stations covering an area of 700×700 m2. The main goal for the combined measurements of KASCADE and Grande is the investigation of the energy spectrum and composition of primary cosmic rays in the energy range of 1016 to 1018 eV. In this paper an overview of the KASCADE-Grande experiment and recent results will be presented.

Model-based adaptive 3D sonar reconstruction in reverberating environments.

PubMed

Saucan, Augustin-Alexandru; Sintes, Christophe; Chonavel, Thierry; Caillec, Jean-Marc Le

2015-10-01

In this paper, we propose a novel model-based approach for 3D underwater scene reconstruction, i.e., bathymetry, for side scan sonar arrays in complex and highly reverberating environments like shallow water areas. The presence of multipath echoes and volume reverberation generates false depth estimates. To improve the resulting bathymetry, this paper proposes and develops an adaptive filter, based on several original geometrical models. This multimodel approach makes it possible to track and separate the direction of arrival trajectories of multiple echoes impinging the array. Echo tracking is perceived as a model-based processing stage, incorporating prior information on the temporal evolution of echoes in order to reject cluttered observations generated by interfering echoes. The results of the proposed filter on simulated and real sonar data showcase the clutter-free and regularized bathymetric reconstruction. Model validation is carried out with goodness of fit tests, and demonstrates the importance of model-based processing for bathymetry reconstruction.

KSC-00padig052

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, Fla. -- As the early morning sky lights up, Space Shuttle Endeavour inches its way to Launch Pad 39B (on the horizon) via the crawlerway that leads from the Vehicle Assembly Building. The Shuttle is atop the Mobile Launcher Platform (MLP). Visible beneath the MLP is the crawler-transporter, which moves on four double-tracked crawlers. Each shoe on the crawler track weighs a ton. Unloaded, the transporter weighs 6 million pounds and moves at 2 mph. The maximum speed of the loaded transporter is 1 mph. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC00padig052

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, Fla. -- As the early morning sky lights up, Space Shuttle Endeavour inches its way to Launch Pad 39B (on the horizon) via the crawlerway that leads from the Vehicle Assembly Building. The Shuttle is atop the Mobile Launcher Platform (MLP). Visible beneath the MLP is the crawler-transporter, which moves on four double-tracked crawlers. Each shoe on the crawler track weighs a ton. Unloaded, the transporter weighs 6 million pounds and moves at 2 mph. The maximum speed of the loaded transporter is 1 mph. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

Obscura telescope with a MEMS micromirror array for space observation of transient luminous phenomena or fast-moving objects.

PubMed

Park, J H; Garipov, G K; Jeon, J A; Khrenov, B A; Kim, J E; Kim, M; Kim, Y K; Lee, C-H; Lee, J; Na, G W; Nam, S; Park, I H; Park, Y-S

2008-12-08

We introduce a novel telescope consisting of a pinhole-like camera with rotatable MEMS micromirrors substituting for pinholes. The design is ideal for observations of transient luminous phenomena or fast-moving objects, such as upper atmospheric lightning and bright gamma ray bursts. The advantage of the MEMS "obscura telescope" over conventional cameras is that it is capable both of searching for events over a wide field of view, and fast zooming to allow detailed investigation of the structure of events. It is also able to track the triggering object to investigate its space-time development, and to center the interesting portion of the image on the photodetector array. We present the proposed system and the test results for the MEMS obscura telescope which has a field of view of 11.3 degrees, sixteen times zoom-in and tracking within 1 ms. (c) 2008 Optical Society of America

Transparent thin shield for radio frequency transmit coils.

PubMed

Rivera, Debra S; Schulz, Jessica; Siegert, Thomas; Zuber, Verena; Turner, Robert

2015-02-01

To identify a shielding material compatible with optical head-motion tracking for prospective motion correction and which minimizes radio frequency (RF) radiation losses at 7 T without sacrificing line-of-sight to an imaging target. We evaluated a polyamide mesh coated with silver. The thickness of the coating was approximated from the composition ratio provided by the material vendor and validated by an estimate derived from electrical conductivity and light transmission measurements. The performance of the shield is compared to a split-copper shield in the context of a four-channel transmit-only loop array. The mesh contains less than a skin-depth of silver coating (300 MHz) and attenuates light by 15 %. Elements of the array vary less in the presence of the mesh shield as compared to the split-copper shield indicating that the array behaves more symmetrically with the mesh shield. No degradation of transmit efficiency was observed for the mesh as compared to the split-copper shield. We present a shield compatible with future integration of camera-based motion-tracking systems. Based on transmit performance and eddy-current evaluations the mesh shield is appropriate for use at 7 T.

A Study of a Two Stage Maximum Power Point Tracking Control of a Photovoltaic System under Partially Shaded Insolation Conditions

NASA Astrophysics Data System (ADS)

Kobayashi, Kenji; Takano, Ichiro; Sawada, Yoshio

A photovoltaic array shows relatively low output power density, and has a greatly drooping Current-Voltage (I-V) characteristic. Therefore, Maximum Power Point Tracking (MPPT) control is used to maximize the output power of the array. Many papers have been reported in relation to MPPT. However, the Current-Power (I-P) curve sometimes shows multi-local maximum points mode under non-uniform insolation conditions. The operating point of the PV system tends to converge to a local maximum output point which is not the real maximal output point on the I-P curve. Some papers have been also reported, trying to avoid this difficulty. However most of those control systems become rather complicated. Then, the two stage MPPT control method is proposed in this paper to realize a relatively simple control system which can track the real maximum power point even under non-uniform insolation conditions. The feasibility of this control concept is confirmed for steady insolation as well as for rapidly changing insolation by simulation study using software PSIM and LabVIEW. In addition, simulated experiment confirms fundament al operation of the two stage MPPT control.

Predictability of GNSS signal observations in support of Space Situational Awareness using passive radar

NASA Astrophysics Data System (ADS)

Mahmud, M. S.; Lambert, A.; Benson, C.

2015-07-01

GNSS signals have been proposed as emitters of opportunity to enhance Space Situational Awareness (SSA) by tracking small items of space debris using bistatic radar. Although the scattered GNSS signal levels from small items of space debris are incredibly low, the dynamic disturbances of the observed object are very small, and the phase of the scattered signals is well behaved. It is therefore plausible that coherent integration periods on the order of many minutes could be achieved. However, even with long integration periods, very large receiver arrays with extensive, but probably viable, processing are required to recover the scattered signal. Such large arrays will be expensive, and smaller more affordable arrays will collect insufficient signal power to detect the small objects (relative to wavelength) that are necessary to maintain the necessary phase coherency. The investments necessary to build a large receiver array are unlikely without substantial risk reduction. Pini and Akos have previously reported on use of very large radio telescopes to analyse the short-term modulation performance of GNSS satellite signals. In this work we report on tracking of GPS satellites with a radio-astronomy VLBI antenna system to assess the stability of the observed GPS signal over a time period indicative of that proposed for passive radar. We also confirm some of the processing techniques that may be used in both demonstrations and the final system. We conclude from the limited data set that the signal stability when observed by a high-gain tracking antenna and compared against a high quality, low phase-noise clock is excellent, as expected. We conclude by framing further works to reduce risk for a passive radar SSA capability using GNSS signals. http://www.ignss.org/Conferences/PastConferencePapers/2015ConferencePastPapers/2015PeerReviewedPapers/tabid/147/Default.aspx

Linear array of photodiodes to track a human speaker for video recording

NASA Astrophysics Data System (ADS)

DeTone, D.; Neal, H.; Lougheed, R.

2012-12-01

Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

SOLARTRAK. Solar Array Tracking Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manish, A.B.; Dudley, J.

1995-06-01

SolarTrak used in conjunction with various versions of 68HC11-based SolarTrack hardware boards provides control system for one or two axis solar tracking arrays. Sun position is computed from stored position data and time from an on-board clock/calendar chip. Position feedback can be by one or two offset motor turn counter square wave signals per axis, or by a position potentiometer. A limit of 256 counts resolution is imposed by the on-board analog to digital (A/D) convertor. Control is provided for one or two motors. Numerous options are provided to customize the controller for specific applications. Some options are imposed atmore » compile time, some are setable during operation. Software and hardware board designs are provided for Control Board and separate User Interface Board that accesses and displays variables from Control Board. Controller can be used with range of sensor options ranging from a single turn count sensor per motor to systems using dual turn-count sensors, limit sensors, and a zero reference sensor. Dual axis trackers oriented azimuth elevation, east west, north south, or polar declination can be controlled. Misalignments from these orientations can also be accommodated. The software performs a coordinate transformation using six parameters to compute sun position in misaligned coordinates of the tracker. Parameters account for tilt of tracker in two directions, rotation about each axis, and gear ration errors in each axis. The software can even measure and compute these prameters during an initial setup period if current from a sun position sensor or output from photovoltaic array is available as an anlog voltage to the control board`s A/D port. Wind or emergency stow to aj present position is available triggered by digital or analog signals. Night stow is also available. Tracking dead band is adjustable from narrow to wide. Numerous features of the hardware and software conserve energy for use with battery powered systems.« less

Solar Array Tracking Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maish, Alexander

1995-06-22

SolarTrak used in conjunction with various versions of 68HC11-based SolarTrack hardware boards provides control system for one or two axis solar tracking arrays. Sun position is computed from stored position data and time from an on-board clock/calendar chip. Position feedback can be by one or two offset motor turn counter square wave signals per axis, or by a position potentiometer. A limit of 256 counts resolution is imposed by the on-board analog to digital (A/D) convertor. Control is provided for one or two motors. Numerous options are provided to customize the controller for specific applications. Some options are imposed atmore » compile time, some are setable during operation. Software and hardware board designs are provided for Control Board and separate User Interface Board that accesses and displays variables from Control Board. Controller can be used with range of sensor options ranging from a single turn count sensor per motor to systems using dual turn-count sensors, limit sensors, and a zero reference sensor. Dual axis trackers oriented azimuth elevation, east west, north south, or polar declination can be controlled. Misalignments from these orientations can also be accommodated. The software performs a coordinate transformation using six parameters to compute sun position in misaligned coordinates of the tracker. Parameters account for tilt of tracker in two directions, rotation about each axis, and gear ration errors in each axis. The software can even measure and compute these prameters during an initial setup period if current from a sun position sensor or output from photovoltaic array is available as an anlog voltage to the control board''s A/D port. Wind or emergency stow to aj present position is available triggered by digital or analog signals. Night stow is also available. Tracking dead band is adjustable from narrow to wide. Numerous features of the hardware and software conserve energy for use with battery powered systems.« less

Microprocessor control of multiple peak power tracking DC/DC converters for use with solar cell arrays

NASA Technical Reports Server (NTRS)

Frederick, Martin E. (Inventor); Jermakian, Joel (Inventor)

1991-01-01

A method and an apparatus is provided for efficiently controlling the power output of a solar cell array string or a plurality of solar cell array strings to achieve a maximum amount of output power from the strings under varying conditions of use. Maximum power output from a solar array string is achieved through control of a pulse width modulated DC/DC buck converter which transfers power from a solar array to a load or battery bus. The input voltage from the solar array to the converter is controlled by a pulse width modulation duty cycle, which in turn is controlled by a differential signal controller. By periodically adjusting the control voltage up or down by a small amount and comparing the power on the load or bus with that generated at different voltage values a maximum power output voltage may be obtained. The system is totally modular and additional solar array strings may be added to the system simply by adding converter boards to the system and changing some constants in the controller's control routines.

The application of smart sensor techniques to a solid-state array multispectral sensor

NASA Technical Reports Server (NTRS)

Mcfadin, L. W.

1978-01-01

The solid-state array spectroradiometer (SAS) developed at JSC for remote sensing applications is a multispectral sensor which has no moving parts, is virtually maintenance-free, and has the ability to provide data which requires a minimum of processing. The instrument is based on the 42 x 342 element charge injection device (CID) detector. This system allows the combination of spectral scanning and across-track spatial scanning along with its associated digitization electronics into a single detector.

Terrestrial adaptation of the thermal heliotrope.

NASA Technical Reports Server (NTRS)

Fairbanks, J. W.; Morse, F. H.

1971-01-01

The principle of using bimetal helical coils to cause solar arrays to track the sun in space is presently under consideration for array orientation on several spacecraft. Adaptation of this thermal heliotrope to terrestrial applications introduces additional design considerations. The dominance of solar-radiation energy input to the helical coil over convective energy losses has to be ensured, and wind effects must be minimized. As long as the cost of solar cells remains high, orientation will always result in a significant cost saving for the converter.

The Air-Shower Experiment KASCADE-Grande

NASA Astrophysics Data System (ADS)

Haungs, A.; Apel, W. D.; Arteaga, J. C.; Badea, F.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Klages, H. O.; Kolotaev, Y.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G.; Ulrich, H.; Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; KASCADE-Grande Collaboration

2009-12-01

KASCADE-Grande is an extensive air shower experiment at the Forschungszentrum Karlsruhe, Germany. Main parts of the experiment are the Grande array spread over an area of 700×700 m, the original KASCADE array covering 200×200 m with unshielded and shielded detectors, and additional muon tracking devices. This multi-detector system allows to investigate the energy spectrum, composition, and anisotropies of cosmic rays in the energy range up to 1 EeV. An overview on the performance of the apparatus and first results will be given.

An adaptive array antenna for mobile satellite communications

NASA Technical Reports Server (NTRS)

Milne, Robert

1990-01-01

The design of an adaptive array antenna for land vehicle operation and its performance in an operational satellite system is described. Linear and circularly polarized antenna designs are presented. The acquisition and tracking operation of a satellite is described and the effect on the communications signal is discussed. A number of system requirements are examined that have a major impact on the antenna design. The results of environmental, power handling, and RFI testing are presented and potential problems are identified.

Sonic boom measurements from accelerating supersonic tracked sleds

NASA Technical Reports Server (NTRS)

Reed, J. W.

1974-01-01

Supersonic sled tests on the Sandia 1524-m (5000-ft) track generate sonic booms of sufficient intensity to allow some airblast measurements at distance scales not obtained from wind tunnel or flight tests. During acceleration, an emitted curved boom wave propagates to a caustic, or focus. Detailed measurements around these caustics may help to clarify the overpressure magnification which can occur from real aircraft operations. Six fixed pressure gages have been operated to document the general noise field, and a mobile array of twelve gages.

Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas

DTIC Science & Technology

2007-01-31

progress on the reserach grant "Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas" during the period 1 May 2005 - 31 December...the DOA of target i with respect to the array boresight is given by: O 1sin-1 -/- fD)--F2(. )(1) where d is the spacing between the elements and A, is...wall. A large database was collected for different parameter spaces including number of humans, types of movements, wall types and radar polarization

IAF 15 Draft Paper

NASA Technical Reports Server (NTRS)

Menkin, Evgeny; Juillerat, Robert

2015-01-01

With the International Space Station Program transition from assembly to utilization, focus has been placed on the optimization of essential resources. This includes resources both resupplied from the ground and also resources produced by the ISS. In an effort to improve the use of two of these, the ISS Engineering teams, led by the ISS Program Systems Engineering and Integration Office, undertook an effort to modify the techniques use to perform several key on-orbit events. The primary purposes of this endeavor was to make the ISS more efficient in the use of the Russian-supplied fuel for the propulsive attitude control system and also to minimize the impacts to available ISS power due to the positioning of the ISS solar arrays. Because the ISS solar arrays are sensitive to several factors that are present when propulsive attitude control is used, they must be operated in a manner to protect them from damage. This results in periods of time where the arrays must be positioned, rather than autonomously tracking the sun, resulting in negative impacts to power generated by the solar arrays and consumed by both the ISS core systems and payload customers. A reduction in the number and extent of the events each year that require the ISS to use propulsive attitude control simultaneously accomplishes both these goals. Each instance where the ISS solar arrays normal sun tracking mode must be interrupted represent a need for some level of powerdown of equipment. As the magnitude of payload power requirements increases, and the efficiency of the ISS solar arrays decreases, these powerdowns caused by array positioning, will likely become more significant and could begin to negatively impact the payload operations. Through efforts such as this, the total number of events each year that require positioning of the arrays to unfavorable positions for power generation, in order to protect them against other constraints, are reduced. Optimization of propulsive events and transitioning some of them to non-propulsive CMG control significantly reduces propellant usage on the ISS leading to the reduction of the propellant delivery requirement. This results in move available upmass that can be used for delivering critical dry cargo, additional water, air, crew supplies and science experiments.

Installation package for concentrating solar collector panels

NASA Technical Reports Server (NTRS)

1978-01-01

The concentrating solar collector panels comprise a complete package array consisting of collector panels using modified Fresnel prismatic lenses for a 10 to 1 concentrating ratio, supporting framework, fluid manifolding and tracking drive system, and unassembled components for field erection.

Characterization of switching field distributions in Ising-like magnetic arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fraleigh, Robert D.; Kempinger, Susan; Lammert, Paul E.

The switching field distribution within arrays of single-domain ferromagnetic islands incorporates both island-island interactions and quenched disorder in island geometry. Separating these two contributions is important for disentangling the effects of disorder and interactions in themagnetization dynamics of island arrays. Using submicron, spatially resolved Kerr imaging in an external magnetic field for islands with perpendicular magnetic anisotropy, we map out the evolution of island arrays during hysteresis loops. Resolving and tracking individual islands across four different lattice types and a range of interisland spacings, we can extract the individual switching fields of every island and thereby quantitatively determine the contributionsmore » of interactions and quenched disorder in the arrays. The width of the switching field distribution is found to be well fitted by a simple model comprising the sum of an array-independent contribution (interpreted as disorder induced) and a term proportional to the maximum field the entire rest of the array could exert on a single island, i.e., in a fully polarized state. This supports the claim that disorder in these arrays is primarily a single-island property and provides a methodology by which to quantify such disorder.« less

Characterization of switching field distributions in Ising-like magnetic arrays

NASA Astrophysics Data System (ADS)

Fraleigh, Robert D.; Kempinger, Susan; Lammert, Paul E.; Zhang, Sheng; Crespi, Vincent H.; Schiffer, Peter; Samarth, Nitin

2017-04-01

The switching field distribution within arrays of single-domain ferromagnetic islands incorporates both island-island interactions and quenched disorder in island geometry. Separating these two contributions is important for disentangling the effects of disorder and interactions in the magnetization dynamics of island arrays. Using submicron, spatially resolved Kerr imaging in an external magnetic field for islands with perpendicular magnetic anisotropy, we map out the evolution of island arrays during hysteresis loops. Resolving and tracking individual islands across four different lattice types and a range of interisland spacings, we can extract the individual switching fields of every island and thereby quantitatively determine the contributions of interactions and quenched disorder in the arrays. The width of the switching field distribution is found to be well fitted by a simple model comprising the sum of an array-independent contribution (interpreted as disorder induced) and a term proportional to the maximum field the entire rest of the array could exert on a single island, i.e., in a fully polarized state. This supports the claim that disorder in these arrays is primarily a single-island property and provides a methodology by which to quantify such disorder.

Solar Array Hysteresis and its Interaction with the MPPT System

NASA Astrophysics Data System (ADS)

Fernandez, A.; Baur, C.; Gomez-Carpintero, F.

2014-08-01

It is well known that solar cells have a capacitance in parallel which value changes with the voltage. Depending on the section arrangement on the Solar Array, the power conversion unit connected to it will see a smaller or larger capacitance value and will have to cope with its adverse effects. In the case of converters with an MPPT, this capacitance gives place to an hysteresis effect that might shift the tracking point, reducing the power extracted from the Solar Array. This paper explores the different sides of this issue, from capacitance modelling to the effects on the MPPT. Additionally, this paper analyses a similar interaction between MPPTs and commercial SAS.

Optically interconnected phased arrays

NASA Technical Reports Server (NTRS)

Bhasin, Kul B.; Kunath, Richard R.

1988-01-01

Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed.

A wideband software reconfigurable modem

NASA Astrophysics Data System (ADS)

Turner, J. H., Jr.; Vickers, H.

A wideband modem is described which provides signal processing capability for four Lx-band signals employing QPSK, MSK and PPM waveforms and employs a software reconfigurable architecture for maximum system flexibility and graceful degradation. The current processor uses a 2901 and two 8086 microprocessors per channel and performs acquisition, tracking, and data demodulation for JITDS, GPS, IFF and TACAN systems. The next generation processor will be implemented using a VHSIC chip set employing a programmable complex array vector processor module, a GP computer module, customized gate array modules, and a digital array correlator. This integrated processor has application to a wide number of diverse system waveforms, and will bring the benefits of VHSIC technology insertion into avionic antijam communications systems.

High speed, very large (8 megabyte) first in/first out buffer memory (FIFO)

DOEpatents

Baumbaugh, Alan E.; Knickerbocker, Kelly L.

1989-01-01

A fast FIFO (First In First Out) memory buffer capable of storing data at rates of 100 megabytes per second. The invention includes a data packer which concatenates small bit data words into large bit data words, a memory array having individual data storage addresses adapted to store the large bit data words, a data unpacker into which large bit data words from the array can be read and reconstructed into small bit data words, and a controller to control and keep track of the individual data storage addresses in the memory array into which data from the packer is being written and data to the unpacker is being read.

Advanced propulsion concepts study: Comparative study of solar electric propulsion and laser electric propulsion

NASA Technical Reports Server (NTRS)

Forward, R. L.

1975-01-01

Solar electric propulsion (SEP) and laser electric propulsion (LEP) was compared. The LEP system configuration consists of an 80 kW visible laser source on earth, transmitting via an 8 m diameter adaptively controlled phased array through the atmosphere to a 4 m diameter synchronous relay mirror that tracks the LEP spacecraft. The only significant change in the SEP spacecraft for an LEP mission is the replacement of the two 3.7 m by 33.5 m solar cell arrays with a single 8 m diameter laser photovoltaic array. The solar cell array weight is decreased from 320 kg to 120 kg for an increase in payload of 200 kg and a decrease in specific mass of the power system from 20.5 kg/kW to 7.8 kg/kW.

A novel approach to Hough Transform for implementation in fast triggers

NASA Astrophysics Data System (ADS)

Pozzobon, Nicola; Montecassiano, Fabio; Zotto, Pierluigi

2016-10-01

Telescopes of position sensitive detectors are common layouts in charged particles tracking, and programmable logic devices, such as FPGAs, represent a viable choice for the real-time reconstruction of track segments in such detector arrays. A compact implementation of the Hough Transform for fast triggers in High Energy Physics, exploiting a parameter reduction method, is proposed, targeting the reduction of the needed storage or computing resources in current, or next future, state-of-the-art FPGA devices, while retaining high resolution over a wide range of track parameters. The proposed approach is compared to a Standard Hough Transform with particular emphasis on their application to muon detectors. In both cases, an original readout implementation is modeled.

SU-F-T-41: 3D MTP-TRUS for Prostate Implant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, P

Purpose: Prostate brachytherapy is an effective treatment for early prostate cancer. The current prostate implant is limited to using 2D transrectal ultrassound (TRUS) or machenical motor driven 2D array either in the end or on the side. Real-time 3D images can improve the accuracy of the guidance of prostate implant. The concept of our system is to allow realtime full visualization of the entire prostate with the multiple transverse scan. Methods: The prototype of 3D Multiple-Transverse-Plane Transrectal Ultrasound probe (MTP-TRUS) has been designed by us and manufactured by Blatek inc. It has 7 convex linear arrays and each array hasmore » 96 elements. It is connected to cQuest Fire bird research system (Cephasonics inc.) which is a flexible and configurable ultrasound-development platform. The size of cQuest Firebird system is compact and supports the real-time wireless image transferring. A relay based mux board is designed for the cQuest Firebird system to be able to connect 672 elements. Results: The center frequency of probe is 6MHz±10%. The diameter of probe is 3cm and the length is 20cm. The element pitch is 0.205 mm. Array focus is 30mm and spacing 1.6cm. The beam data for each array was measured and met our expectation. The interface board of MTP-TURS is made and able to connect to cQuest Firebird system. The image display interface is still under the development. Our real-time needle tracking algorithm will be implemented too. Conclusion: Our MTP-TRUS system for prostate implant will be able to acquire real-time 3D images of prostate and do the real-time needle segmentation and tracking. The system is compact and have wireless function.« less

The Abacus/Reflector and Integrated Symmetrical Concentrator: Concepts for Space Solar Power Collection and Transmission

NASA Technical Reports Server (NTRS)

Carrington, Connie; Fikes, John; Gerry, Mark; Perkinson, Don

2000-01-01

New energy sources are vital for the development of emerging nations, and the growth of industry in developed economies. Also vital is the need for these energy sources to be clean and renewable. For the past several years, NASA has been taking a new look at collecting solar energy in space and transmitting it to Earth, to planetary surfaces, and to orbiting spacecraft. Several innovative concepts are being studied for the space segment component of solar power beaming. One is the Abacus/Reflector, a large sun-oriented array structure fixed to the transmitter, and a rotating RF reflector that tracks a receiving rectenna on Earth. This concept eliminates the need for power-conducting slip rings in rotating joints between the solar collectors and the transmitter. Another concept is the Integrated Symmetrical Concentrator (ISC), composed of two very large segmented reflectors which rotate to collect and reflect the incident sunlight onto two centrally-located photovoltaic arrays. Adjacent to the PV arrays is the RF transmitter, which as a unit track the receiving rectenna, again eliminating power-conducting joints, and in addition reducing the cable lengths between the arrays and transmitter. The metering structure to maintain the position of the reflectors is a long mast, oriented perpendicular to the equatorial orbit plane. This paper presents a status of ongoing systems studies and configurations for the Abacus/Reflector and the ISC concepts, and a top-level study of packaging for launch and assembly.

Solar Radiation on Mars: Tracking Photovoltaic Array

NASA Technical Reports Server (NTRS)

Appelbaum, Joseph; Flood, Dennis J.; Crutchik, Marcos

1994-01-01

A photovoltaic power source for surface-based operation on Mars can offer many advantages. Detailed information on solar radiation characteristics on Mars and the insolation on various types of collector surfaces are necessary for effective design of future planned photovoltaic systems. In this article we have presented analytical expressions for solar radiation calculation and solar radiation data for single axis (of various types) and two axis tracking surfaces and compared the insulation to horizontal and inclined surfaces. For clear skies (low atmospheric dust load) tracking surfaces resulted in higher insolation than stationary surfaces, whereas for highly dusty atmospheres, the difference is small. The insolation on the different types of stationary and tracking surfaces depend on latitude, season and optical depth of the atmosphere, and the duration of system operation. These insolations have to be compared for each mission.

Real-time model-based vision system for object acquisition and tracking

NASA Technical Reports Server (NTRS)

Wilcox, Brian; Gennery, Donald B.; Bon, Bruce; Litwin, Todd

1987-01-01

A machine vision system is described which is designed to acquire and track polyhedral objects moving and rotating in space by means of two or more cameras, programmable image-processing hardware, and a general-purpose computer for high-level functions. The image-processing hardware is capable of performing a large variety of operations on images and on image-like arrays of data. Acquisition utilizes image locations and velocities of the features extracted by the image-processing hardware to determine the three-dimensional position, orientation, velocity, and angular velocity of the object. Tracking correlates edges detected in the current image with edge locations predicted from an internal model of the object and its motion, continually updating velocity information to predict where edges should appear in future frames. With some 10 frames processed per second, real-time tracking is possible.

Time-resolved large-scale volumetric pressure fields of an impinging jet from dense Lagrangian particle tracking

NASA Astrophysics Data System (ADS)

Huhn, F.; Schanz, D.; Manovski, P.; Gesemann, S.; Schröder, A.

2018-05-01

Time-resolved volumetric pressure fields are reconstructed from Lagrangian particle tracking with high seeding concentration using the Shake-The-Box algorithm in a perpendicular impinging jet flow with exit velocity U=4 m/s (Re˜ 36,000) and nozzle-plate spacing H/D=5. Helium-filled soap bubbles are used as tracer particles which are illuminated with pulsed LED arrays. A large measurement volume has been covered (cloud of tracked particles in a volume of 54 L, ˜ 180,000 particles). The reconstructed pressure field has been validated against microphone recordings at the wall with high correlation coefficients up to 0.88. In a reduced measurement volume (13 L), dense Lagrangian particle tracking is shown to be feasable up to the maximal possible jet velocity of U=16 m/s.

The Sun Radio Imaging Space Experiment (SunRISE) Mission

NASA Astrophysics Data System (ADS)

Lazio, Joseph; Kasper, Justin; Maksimovic, Milan; Alibay, Farah; Amiri, Nikta; Bastian, Tim; Cohen, Christina; Landi, Enrico; Manchester, Ward; Reinard, Alysha; Schwadron, Nathan; Cecconi, Baptiste; Hallinan, Gregg; Hegedus, Alex; Krupar, Vratislav; Zaslavsky, Arnaud

2017-04-01

Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 RS. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (ν ≳ 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (≲ 3RS). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Characterization and Design of Digital Pointing Subsystem for Optical Communication Demonstrator

NASA Technical Reports Server (NTRS)

Racho, C.; Portillo, A.

1998-01-01

The Optical Communications Demonstrator (OCD) is a laboratory-based lasercom demonstration terminal designed to validate several key technologies, including beacon acquisition, high bandwidth tracking, precision bearn pointing, and point-ahead compensation functions. It has been under active development over the past few years. The instrument uses a CCD array detector for both spatial acquisition and high-bandwidth tracking, and a fiber coupled laser transmitter. The array detector tracking concept provides wide field-of-view acquisition and permits effective platform jitter compensation and point-ahead control using only one steering mirror. This paper describes the detailed design and characterization of the digital control loop system which includes the Fast Steering Mirror (FSM), the CCD image tracker, and the associated electronics. The objective is to improve the overall system performance using laboratory measured data. The. design of the digital control loop is based on a linear time invariant open loop model. The closed loop performance is predicted using the theoretical model. With the digital filter programmed into the OCD control software, data is collected to verify the predictions. This paper presents the results of the, system modeling and performance analysis. It has been shown that measurement data closely matches theoretical predictions. An important part of the laser communication experiment is the ability of FSM to track the laser beacon within the. required tolerances. The pointing must be maintained to an accuracy that is much smaller than the transmit signal beamwidth. For an earth orbit distance, the system must be able to track the receiving station to within a few microradians. The failure. to do so will result in a severely degraded system performance.

Migratory behavior of eastern North Pacific gray whales tracked using a hydrophone array

PubMed Central

Helble, Tyler A.; D’Spain, Gerald L.; Weller, David W.; Wiggins, Sean M.; Hildebrand, John A.

2017-01-01

Eastern North Pacific gray whales make one of the longest annual migrations of any mammal, traveling from their summer feeding areas in the Bering and Chukchi Seas to their wintering areas in the lagoons of Baja California, Mexico. Although a significant body of knowledge on gray whale biology and behavior exists, little is known about their vocal behavior while migrating. In this study, we used a sparse hydrophone array deployed offshore of central California to investigate how gray whales behave and use sound while migrating. We detected, localized, and tracked whales for one full migration season, a first for gray whales. We verified and localized 10,644 gray whale M3 calls and grouped them into 280 tracks. Results confirm that gray whales are acoustically active while migrating and their swimming and acoustic behavior changes on daily and seasonal time scales. The seasonal timing of the calls verifies the gray whale migration timing determined using other methods such as counts conducted by visual observers. The total number of calls and the percentage of calls that were part of a track changed significantly over both seasonal and daily time scales. An average calling rate of 5.7 calls/whale/day was observed, which is significantly greater than previously reported migration calling rates. We measured a mean speed of 1.6 m/s and quantified heading, direction, and water depth where tracks were located. Mean speed and water depth remained constant between night and day, but these quantities had greater variation at night. Gray whales produce M3 calls with a root mean square source level of 156.9 dB re 1 μPa at 1 m. Quantities describing call characteristics were variable and dependent on site-specific propagation characteristics. PMID:29084266

The Sun Radio Imaging Space Experiment (SunRISE) Mission

NASA Astrophysics Data System (ADS)

Kasper, J. C.; Lazio, J.; Alibay, F.; Amiri, N.; Bastian, T.; Cohen, C.; Landi, E.; Hegedus, A. M.; Maksimovic, M.; Manchester, W.; Reinard, A.; Schwadron, N.; Cecconi, B.; Hallinan, G.; Krupar, V.

2017-12-01

Radio emission from coronal mass ejections (CMEs) is a direct tracer of particle acceleration in the inner heliosphere and potential magnetic connections from the lower solar corona to the larger heliosphere. Energized electrons excite Langmuir waves, which then convert into intense radio emission at the local plasma frequency, with the most intense acceleration thought to occur within 20 R_S. The radio emission from CMEs is quite strong such that only a relatively small number of antennas is required to detect and map it, but many aspects of this particle acceleration and transport remain poorly constrained. Ground-based arrays would be quite capable of tracking the radio emission associated with CMEs, but absorption by the Earth's ionosphere limits the frequency coverage of ground-based arrays (nu > 15 MHz), which in turn limits the range of solar distances over which they can track the radio emission (< 3 R_S). The state-of-the-art for tracking such emission from space is defined by single antennas (Wind/WAVES, Stereo/SWAVES), in which the tracking is accomplished by assuming a frequency-to-density mapping; there has been some success in triangulating the emission between the spacecraft, but considerable uncertainties remain. We describe the Sun Radio Imaging Space Experiment (SunRISE) mission concept: A constellation of small spacecraft in a geostationary graveyard orbit designed to localize and track radio emissions in the inner heliosphere. Each spacecraft would carry a receiving system for observations below 25 MHz, and SunRISE would produce the first images of CMEs more than a few solar radii from the Sun. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Migratory behavior of eastern North Pacific gray whales tracked using a hydrophone array.

PubMed

Guazzo, Regina A; Helble, Tyler A; D'Spain, Gerald L; Weller, David W; Wiggins, Sean M; Hildebrand, John A

2017-01-01

Eastern North Pacific gray whales make one of the longest annual migrations of any mammal, traveling from their summer feeding areas in the Bering and Chukchi Seas to their wintering areas in the lagoons of Baja California, Mexico. Although a significant body of knowledge on gray whale biology and behavior exists, little is known about their vocal behavior while migrating. In this study, we used a sparse hydrophone array deployed offshore of central California to investigate how gray whales behave and use sound while migrating. We detected, localized, and tracked whales for one full migration season, a first for gray whales. We verified and localized 10,644 gray whale M3 calls and grouped them into 280 tracks. Results confirm that gray whales are acoustically active while migrating and their swimming and acoustic behavior changes on daily and seasonal time scales. The seasonal timing of the calls verifies the gray whale migration timing determined using other methods such as counts conducted by visual observers. The total number of calls and the percentage of calls that were part of a track changed significantly over both seasonal and daily time scales. An average calling rate of 5.7 calls/whale/day was observed, which is significantly greater than previously reported migration calling rates. We measured a mean speed of 1.6 m/s and quantified heading, direction, and water depth where tracks were located. Mean speed and water depth remained constant between night and day, but these quantities had greater variation at night. Gray whales produce M3 calls with a root mean square source level of 156.9 dB re 1 μPa at 1 m. Quantities describing call characteristics were variable and dependent on site-specific propagation characteristics.

DSN Scheduling Engine

NASA Technical Reports Server (NTRS)

Clement, Bradley; Johnston, Mark; Wax, Allan; Chouinard, Caroline

2008-01-01

The DSN (Deep Space Network) Scheduling Engine targets all space missions that use DSN services. It allows clients to issue scheduling, conflict identification, conflict resolution, and status requests in XML over a Java Message Service interface. The scheduling requests may include new requirements that represent a set of tracks to be scheduled under some constraints. This program uses a heuristic local search to schedule a variety of schedule requirements, and is being infused into the Service Scheduling Assembly, a mixed-initiative scheduling application. The engine resolves conflicting schedules of resource allocation according to a range of existing and possible requirement specifications, including optional antennas; start of track and track duration ranges; periodic tracks; locks on track start, duration, and allocated antenna; MSPA (multiple spacecraft per aperture); arraying/VLBI (very long baseline interferometry)/delta DOR (differential one-way ranging); continuous tracks; segmented tracks; gap-to-track ratio; and override or block-out of requirements. The scheduling models now include conflict identification for SOA(start of activity), BOT (beginning of track), RFI (radio frequency interference), and equipment constraints. This software will search through all possible allocations while providing a best-effort solution at any time. The engine reschedules to accommodate individual emergency tracks in 0.2 second, and emergency antenna downtime in 0.2 second. The software handles doubling of one mission's track requests over one week (to 42 total) in 2.7 seconds. Further tests will be performed in the context of actual schedules.

Large gamma-ray detector arrays and electromagnetic separators

NASA Astrophysics Data System (ADS)

Lee, I.-Yang

2013-12-01

The use of large gamma-ray detector arrays with electromagnetic separators is a powerful combination. Various types of gamma-ray detectors have been used; some provide high detector efficiency such as scintillation detector array, others use Ge detectors for good energy resolution, and recently developed Ge energy tracking arrays gives both high peak-to-background ratio and position resolution. Similarly, different types of separators were used to optimize the performance under different experimental requirements and conditions. For example, gas-filled separators were used in heavy element studies for their large efficiency and beam rejection factor. Vacuum separators with good isotope resolution were used in transfer and fragmentation reactions for the study of nuclei far from stability. This paper presents results from recent experiments using gamma-ray detector arrays in combination with electromagnetic separators, and discusses the physics opportunities provided by these instruments. In particular, we review the performance of the instruments currently in use, and discuss the requirements of instruments for future radioactive beam accelerator facilities.

Design and development of a brushless, direct drive solar array reorientation system

NASA Technical Reports Server (NTRS)

Jessee, R. D.

1972-01-01

This report covers the design and development of the laboratory model, and is essentially a compilation of reports covering the system and its various parts. To enhance completeness, the final report of Phase 1 covering circuit development of the controller is also included. A controller was developed for a brushless, direct-drive, single axis solar array reorientation system for earth-pointed, passively-stabilized spacecraft. A control systems was designed and breadboard circuits were built and tested for performance. The controller is designed to take over automatic control of the array on command after the spacecraft is stabilized in orbit. The controller will orient the solar array to the sun vector and automatically track to maintain proper orientation. So long as the orbit is circular, orientation toward the sun is maintained even though the spacecraft goes into the shadow of the earth. Particular attention was given in the design to limit reaction between the array and the spacecraft.

Chimpanzees (Pan troglodytes) use markers to monitor the movement of a hidden item.

PubMed

Beran, Michael J; Beran, Mary M; Menzel, Charles R

2005-10-01

Four chimpanzees (Pan troglodytes) monitored the movement of hidden items in arrays of opaque cups. A chocolate candy was hidden in an array of four cups and temporarily presented paper markers indicated the location of the candy (which otherwise was not visible). These markers were either non-symbolic or symbolic (lexigram) stimuli that in other contexts acted as a label for the hidden candy, and the array was either rotated 180 degrees after the marker was removed or the array remained in the same location. For three of four chimpanzees, performance was better than chance in all conditions and there was no effect of the type of marker. These experiments indicate that chimpanzees can track the movement of a hidden item in an array of identical cups even when they never see the item itself, but only see a temporarily presented marker for the location of that item. However, there was no benefit to the use of symbolic as opposed to non-symbolic stimuli in this performance.

Hybrid Ni/SiO2/Au dimer arrays for high-resolution refractive index sensing

NASA Astrophysics Data System (ADS)

Pourjamal, Sara; Kataja, Mikko; Maccaferri, Nicolò; Vavassori, Paolo; van Dijken, Sebastiaan

2018-05-01

We introduce a novel magnetoplasmonic sensor concept for sensitive detection of refractive index changes. The sensor consists of a periodic array of Ni/SiO2/Au dimer nanodisks. Combined effects of near-field interactions between the Ni and Au disks within the individual dimers and far-field diffractive coupling between the dimers of the array produce narrow linewidth features in the magneto-optical Faraday spectrum. We associate these features with the excitation of surface lattice resonances and show that they exhibit a spectral shift when the refractive index of the surrounding environment is varied. Because the resonances are sharp, refractive index changes are accurately detected by tracking the wavelength where the Faraday signal crosses 0. Compared to random distributions of pure Ni nanodisks or Ni/SiO2/Au dimers or periodic arrays of Ni nanodisks, the sensing figure of merit of the hybrid magnetoplasmonic array is more than one order of magnitude larger.

Amorphous silicon cell array powered solar tracking apparatus

DOEpatents

Hanak, Joseph J.

1985-01-01

An array of an even number of amorphous silicon solar cells are serially connected between first and second terminals of opposite polarity. The terminals are connected to one input terminal of a DC motor whose other input terminal is connected to the mid-cell of the serial array. Vane elements are adjacent the end cells to selectively shadow one or the other of the end cells when the array is oriented from a desired attitude relative to the sun. The shadowing of one cell of a group of cells on one side of the mid-cell reduces the power of that group substantially so that full power from the group of cells on the other side of the mid-cell drives the motor to reorient the array to the desired attitude. The cell groups each have a full power output at the power rating of the motor. When the array is at the desired attitude the power output of the two groups of cells balances due to their opposite polarity so that the motor remains unpowered.

Propulsion and perception in intermediate Re regimes: aquatic microcrustacean copepod responses to wake structures.

NASA Astrophysics Data System (ADS)

Yen, J.; Pender Healy, L. A.; Heaphy, M.

2016-02-01

Flow sensing by the mechanoreceptive cuticular arrays of sensors on copepods has been shaped by over 400 million years of evolution and plays an important role in predator avoidance, foraging, mating, and rheotaxis. These 3D wakes are produced by animal propulsive activities and contain cues that guide these key survival responses. We have demonstrated that the fluid mechanical and chemical information retained in the hydrodynamic envelope can be interpreted by suitable sensor arrays; copepod sensor arrays are capable of perceiving minute differences in wake structures. Temora longicornis, a coastal marine copepod, and Hesperodiaptomus shoshone, a high-alpine freshwater lake copepod, track laminar trails. High-speed videography coupled with high-magnification Schlieren optics enabled us to visualize the deformation of the trail signal and the propulsive movements of the male copepod. Males followed the trail mimic and our observations show clear differences between the marine and freshwater species. Comparative analyses reveal tracking mechanisms that differ in sensor location with respect to the trail and locomotory kinematics. Copepods perform directed motions that lead them to a stimulus source in the absence of other collimating stimuli. Tracking by the copepod around the trail allows it to have one or numerous sensors inside and outside the trail to facilitate edge detection using spatial sampling. The advantage of this remarkable behavior of following trails fast and accurately is to encounter mates or food patches more frequently, thus contributing to population recruitment and energy transfer up the trophic food web. Precise mate and food finding strategies found for pelagic copepods may be a key adaptation, promoting survival in these open-ocean planktonic populations.

L-Band Ionosphere Scintillations Observed by A GNSS Receiver Array at HAARP

NASA Astrophysics Data System (ADS)

Morton, Y.; Pelgrum, W.; van Graas, F.

2011-12-01

As we enter a new solar maximum period, GNSS receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to gain better understandings of scintillation effects on GNSS signals. During the past decade, many GPS receivers have been deployed around the globe to monitor ionosphere scintillations. Most of these GPS receivers are commercial receivers whose tracking mechanisms are not designed to operate under ionosphere scintillation. When strong scintillations occur, these receivers will either generate erroneous outputs or completely lose lock. Even when the scintillation is mild, the tracking loop outputs are not true representation of the signal parameters due the tracking loop transfer function. High quality, unprocessed GNSS receiver front end raw IF samples collected during ionosphere scintillations are necessary to produce realistic scintillation signal parameter estimations. In this presentation, we will update our effort in establishing a unique GNSS receiver array at HAARP, Alaska to collect GPS and GLONASS satellite signals at various stages of the GNSS receiver processing. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array as well as additional on-site diagnostic instrumentation measurements obtained from two active heating experiment campaigns conducted in 2011 will be presented. Additionally, we will also highlight and contrast the artificial heating experiment results with observations of natural scintillation events captured by our receivers using an automatic event trigger mechanism during the past year. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

Restructured Freedom configuration characteristics

NASA Technical Reports Server (NTRS)

Troutman, Patrick A.; Heck, Michael L.; Kumar, Renjith R.; Mazanek, Daniel D.

1991-01-01

In Jan. 1991, the LaRc SSFO performed an assessment of the configuration characteristics of the proposed pre-integrated Space Station Freedom (SSF) concept. Of particular concern was the relationship of solar array operation and orientation with respect to spacecraft controllability. For the man-tended configuration (MTC), it was determined that torque equilibrium attitude (TEA) seeking Control Moment Gyroscope (CMG) control laws could not always maintain attitude. The control problems occurred when the solar arrays were tracking the sun to produce full power while flying in an arrow or gravity gradient flight mode. The large solar array articulations that sometimes result from having the functions of the alpha and beta joints reversed on MTC induced large product of inertia changes that can invalidate the control system gains during an orbit. Several modified sun tracking techniques were evaluated with respect to producing a controllable configuration requiring no modifications to the CMG control algorithms. Another assessment involved the permanently manned configuration (PMC) which has a third asymmetric PV unit on one side of the transverse boom. Recommendations include constraining alpha rotations for MTC in the arrow and gravity gradient flight modes and perhaps developing new non-TEA seeking control laws. Recommendations for PMC include raising the operational altitude and moving to a symmetric configuration as soon as possible.

Lighting Condition Analysis for Mars' Moon Phobos

NASA Technical Reports Server (NTRS)

Li, Zu Qun; de Carufel, Guy; Crues, Edwin Z.; Bielski, Paul

2016-01-01

This study used high fidelity computer simulation to investigate the lighting conditions, specifically the solar radiation flux over the surface, on Phobos. Ephemeris data from the Jet Propulsion Laboratory (JPL) DE405 model was used to model the state of the Sun, Earth, Moon, and Mars. An occultation model was developed to simulate Phobos' self-shadowing and its solar eclipses by Mars. The propagated Phobos state was compared with data from JPL's Horizon system to ensure the accuracy of the result. Results for Phobos lighting conditions over one Martian year are presented, which include the duration of solar eclipses, average solar radiation intensity, surface exposure time, and radiant exposure for both sun tracking and fixed solar arrays. The results show that: Phobos' solar eclipse time varies throughout the Martian year, with longer eclipse durations during the Martian northern spring and fall seasons and no eclipses during the Martian northern summer and winter seasons; solar radiation intensity is close to minimum in late spring and close to maximum in late fall; exposure time per orbit is relatively constant over the surface during the spring and fall but varies with latitude during the summer and winter; and Sun tracking solar arrays generate more energy than a fixed solar array. A usage example of the result is also present in this paper to demonstrate the utility.

Integrated Reconfigurable Aperture, Digital Beam Forming, and Software GPS Receiver for UAV Navigation

DTIC Science & Technology

2007-12-11

Implemented both carrier and code phase tracking loop for performance evaluation of a minimum power beam forming algorithm and null steering algorithm...4 Antennal Antenna2 Antenna K RF RF RF ct, Ct~2 ChKx1 X2 ....... Xk A W ~ ~ =Z, x W ,=1 Fig. 5. Schematics of a K-element antenna array spatial...adaptive processor Antennal Antenna K A N-i V/ ( Vil= .i= VK Fig. 6. Schematics of a K-element antenna array space-time adaptive processor Two additional

A decametric wavelength radio telescope for interplanetary scintillation observations

NASA Technical Reports Server (NTRS)

Cronyn, W. M.; Shawhan, S. D.

1975-01-01

A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.

Advanced sensor-simulation capability

NASA Astrophysics Data System (ADS)

Cota, Stephen A.; Kalman, Linda S.; Keller, Robert A.

1990-09-01

This paper provides an overview of an advanced simulation capability currently in use for analyzing visible and infrared sensor systems. The software system, called VISTAS (VISIBLE/INFRARED SENSOR TRADES, ANALYSES, AND SIMULATIONS) combines classical image processing techniques with detailed sensor models to produce static and time dependent simulations of a variety of sensor systems including imaging, tracking, and point target detection systems. Systems modelled to date include space-based scanning line-array sensors as well as staring 2-dimensional array sensors which can be used for either imaging or point source detection.

Modeling and Implementing a Digitally Embedded Maximum Power Point Tracking Algorithm and a Series-Loaded Resonant DC-DC Converter to Integrate a Photovoltaic Array with a Micro-Grid

DTIC Science & Technology

2014-09-01

These renewable energy sources can include solar, wind, geothermal , biomass, hydroelectric, and nuclear. Of these sources, photovoltaic (PV) arrays...renewable energy source [1]. These renewable energy sources can include solar, wind, geothermal , biomass, hydroelectric, and nuclear. Of these sources...26, May 2011. [6] H. G. Xu, J. P. He, Y. Qin, and Y. H. Li, “Energy management and control strategy for DC micro-grid in data center,” China

Steerable Space Fed Lens Array for Low-Cost Adaptive Ground Station Applications

NASA Technical Reports Server (NTRS)

Lee, Richard Q.; Popovic, Zoya; Rondineau, Sebastien; Miranda, Felix A.

2007-01-01

The Space Fed Lens Array (SFLA) is an alternative to a phased array antenna that replaces large numbers of expensive solid-state phase shifters with a single spatial feed network. SFLA can be used for multi-beam application where multiple independent beams can be generated simultaneously with a single antenna aperture. Unlike phased array antennas where feed loss increases with array size, feed loss in a lens array with more than 50 elements is nearly independent of the number of elements, a desirable feature for large apertures. In addition, SFLA has lower cost as compared to a phased array at the expense of total volume and complete beam continuity. For ground station applications, both of these tradeoff parameters are not important and can thus be exploited in order to lower the cost of the ground station. In this paper, we report the development and demonstration of a 952-element beam-steerable SFLA intended for use as a low cost ground station for communicating and tracking of a low Earth orbiting satellite. The dynamic beam steering is achieved through switching to different feed-positions of the SFLA via a beam controller.

Azimuthal resolution degradation due to ocean surface motion in focused arrays and SARS

NASA Astrophysics Data System (ADS)

1990-06-01

During the meeting at WHOI (5-18-90), a discussion arose of the ability of the focused array to simulate the R/v ratios typical of airborne and/or spaceborne SARs. In particular, the ability was questioned of the focused array to yield the same azimuthal resolution, rho, as the SAR. Although the focused array can be sampled to yield the same azimuthal resolution as the SAR, it is likely that the images generated by the focused array will not be identical to those produced by a SAR with the same azimuth resolution. For a true SAR, biases in the Doppler history of azimuthally traveling waves due to their along-track motion will cause shifts in their apparent position. This will cause waves which are physically at one location to shift over several pixel widths in the image. The limited swath width of the focused array will prevent if from observing scattered power from waves falling outside the swath, thus such waves will not affect the image formed within the swath, as would happen in the SAR. Thus, it is likely that the focused array will not yield the same image as a SAR having the same resolution.

A Methodology to Analyze Photovoltaic Tracker Uptime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, Matthew T; Ruth, Dan

A metric is developed to analyze the daily performance of single-axis photovoltaic (PV) trackers. The metric relies on comparing correlations between the daily time series of the PV power output and an array of simulated plane-of-array irradiances for the given day. Mathematical thresholds and a logic sequence are presented, so the daily tracking metric can be applied in an automated fashion on large-scale PV systems. The results of applying the metric are visually examined against the time series of the power output data for a large number of days and for various systems. The visual inspection results suggest that overall,more » the algorithm is accurate in identifying stuck or functioning trackers on clear-sky days. Visual inspection also shows that there are days that are not classified by the metric where the power output data may be sufficient to identify a stuck tracker. Based on the daily tracking metric, uptime results are calculated for 83 different inverters at 34 PV sites. The mean tracker uptime is calculated at 99% based on 2 different calculation methods. The daily tracking metric clearly has limitations, but as there is no existing metrics in the literature, it provides a valuable tool for flagging stuck trackers.« less

Ultrasound Flow Mapping for the Investigation of Crystal Growth.

PubMed

Thieme, Norman; Bonisch, Paul; Meier, Dagmar; Nauber, Richard; Buttner, Lars; Dadzis, Kaspars; Patzold, Olf; Sylla, Lamine; Czarske, Jurgen

2017-04-01

A high energy conversion and cost efficiency are keys for the transition to renewable energy sources, e.g., solar cells. The efficiency of multicrystalline solar cells can be improved by enhancing the understanding of its crystallization process, especially the directional solidification. In this paper, a novel measurement system for the characterization of flow phenomena and solidification processes in low-temperature model experiments on the basis of ultrasound (US) Doppler velocimetry is described. It captures turbulent flow phenomena in two planes with a frame rate of 3.5 Hz and tracks the shape of the solid-liquid interface during multihour experiments. Time-resolved flow mapping is performed using four linear US arrays with a total of 168 transducer elements. Long duration measurements are enabled through an online, field-programmable gate array (FPGA)-based signal processing. Nine single US transducers allow for in situ tracking of a solid-liquid interface. Results of flow and solidification experiments in the model experiment are presented and compared with numerical simulation. The potential of the developed US system for measuring turbulent flows and for tracking the solidification front during a directional crystallization process is demonstrated. The results of the model experiments are in good agreement with numerical calculations and can be used for the validation of numerical models, especially the selection of the turbulence model.

Development and testing of a magnetic position sensor system for automotive and avionics applications

NASA Astrophysics Data System (ADS)

Jacobs, Bryan C.; Nelson, Carl V.

2001-08-01

A magnetic sensor system has been developed to measure the 3-D location and orientation of a rigid body relative to an array of magnetic dipole transmitters. A generalized solution to the measurement problem has been formulated, allowing the transmitter and receiver parameters (position, orientation, number, etc.) to be optimized for various applications. Additionally, the method of images has been used to mitigate the impact of metallic materials in close proximity to the sensor. The resulting system allows precise tracking of high-speed motion in confined metal environments. The sensor system was recently configured and tested as an abdomen displacement sensor for an automobile crash-test dummy. The test results indicate a positional accuracy of approximately 1 mm rms during 20 m/s motions. The dynamic test results also confirmed earlier covariance model predictions, which were used to optimize the sensor geometry. A covariance analysis was performed to evaluate the applicability of this magnetic position system for tracking a pilot's head motion inside an aircraft cockpit. Realistic design parameters indicate that a robust tracking system, consisting of lightweight pickup coils mounted on a pilot's helmet, and an array of transmitter coils distributed throughout a cockpit, is feasible. Recent test and covariance results are presented.

Baseline monitoring using aircraft laser ranging. [spaceborne laser simulation and aircraft laser tracking

NASA Technical Reports Server (NTRS)

Krabill, W. B.; Hoge, F. E.; Martin, C. F.

1982-01-01

The use of aircraft laser ranging for the determination of baselines between ground based retroreflectors was investigated via simulations and with tests at Wallops Flight Center using the Airborne Oceanographic Lidar (AOL) on the Wallops C-54 aircraft ranging to a reflector array deployed around one of the Wallops runways. The aircraft altitude and reflector spacing were chosen on the basis of scaled down modeling of spacecraft tracking from 1000 km of reflectors separated by some 52 km, or of high altitude (10 km) aircraft tracking of reflectors separated by some 500 m. Aircraft altitudes flown for different passes across the runway reflector array varied from 800 m to 1350 m, with 32 reflectors deployed over an approximtely 300 m x 500 m ground pattern. The AOL transmitted 400 pulses/sec with a scan rate of 5/sec in a near circular pattern, so that the majority of the pulses were reflected by the runway surface or its environs rather than by retroreflectors. The return pulse characteristics clearly showed the high reflectivity of portions of the runway, with several returns indistinguishable in amplitude from reflector returns. For each pass across the reflector field, typically six to ten reflector hits were identified, consistent with that predicted by simulations and the observed transmitted elliptical pulse size.

A Microstrip Patch-Fed Short Backfire Antenna for the Tracking and Data Relay Satellite System-Continuation (TDRSS-C) Multiple Access (MA) Array

NASA Technical Reports Server (NTRS)

Nessel, James A.; Kory, Carol L.; Lambert, Kevin M.; Acosta, Roberto J.

2006-01-01

Short Backfire Antennas (SBAs) are widely utilized for mobile satellite communications, tracking, telemetry, and wireless local area network (WLAN) applications due to their compact structure and excellent radiation characteristics [1-3]. Typically, these SBA s consist of an excitation element (i.e., a half-wavelength dipole), a reflective bottom plane, a planar sub-reflector located above the "exciter", and an outer circular rim. This configuration is capable of achieving gains on the order of 13-15 dBi, but with relatively narrow bandwidths (approx.3%-5%), making it incompatible with the requirements of the next generation enhanced Tracking and Data Relay Satellite System-Continuation (TDRSS-C) Multiple Access (MA) array [1]. Several attempts have been made to enhance the bandwidth performance of the common dipole-fed SBA by employing various other feeding mechanisms (e.g., waveguide, slot) with moderate success [4-5]. In this paper, a novel method of using a microstrip patch is employed for the first time to excite an SBA. The patch element is fed via two H-shaped slots electromagnetically coupled to a broadband hybrid coupler to maintain a wide bandwidth, as well as provide for dual circular polarization capabilities.

Spatial acoustic signal processing for immersive communication

NASA Astrophysics Data System (ADS)

Atkins, Joshua

Computing is rapidly becoming ubiquitous as users expect devices that can augment and interact naturally with the world around them. In these systems it is necessary to have an acoustic front-end that is able to capture and reproduce natural human communication. Whether the end point is a speech recognizer or another human listener, the reduction of noise, reverberation, and acoustic echoes are all necessary and complex challenges. The focus of this dissertation is to provide a general method for approaching these problems using spherical microphone and loudspeaker arrays.. In this work, a theory of capturing and reproducing three-dimensional acoustic fields is introduced from a signal processing perspective. In particular, the decomposition of the spatial part of the acoustic field into an orthogonal basis of spherical harmonics provides not only a general framework for analysis, but also many processing advantages. The spatial sampling error limits the upper frequency range with which a sound field can be accurately captured or reproduced. In broadband arrays, the cost and complexity of using multiple transducers is an issue. This work provides a flexible optimization method for determining the location of array elements to minimize the spatial aliasing error. The low frequency array processing ability is also limited by the SNR, mismatch, and placement error of transducers. To address this, a robust processing method is introduced and used to design a reproduction system for rendering over arbitrary loudspeaker arrays or binaurally over headphones. In addition to the beamforming problem, the multichannel acoustic echo cancellation (MCAEC) issue is also addressed. A MCAEC must adaptively estimate and track the constantly changing loudspeaker-room-microphone response to remove the sound field presented over the loudspeakers from that captured by the microphones. In the multichannel case, the system is overdetermined and many adaptive schemes fail to converge to the true impulse response. This forces the need to track both the near and far end room responses. A transform domain method that mitigates this problem is derived and implemented. Results with a real system using a 16-channel loudspeaker array and 32-channel microphone array are presented.

Simultaneous processing of photographic and accelerator array data from sled impact experiment

NASA Astrophysics Data System (ADS)

Ash, M. E.

1982-12-01

A Quaternion-Kalman filter model is derived to simultaneously analyze accelerometer array and photographic data from sled impact experiments. Formulas are given for the quaternion representation of rotations, the propagation of dynamical states and their partial derivatives, the observables and their partial derivatives, and the Kalman filter update of the state given the observables. The observables are accelerometer and tachometer velocity data of the sled relative to the track, linear accelerometer array and photographic data of the subject relative to the sled, and ideal angular accelerometer data. The quaternion constraints enter through perfect constraint observations and normalization after a state update. Lateral and fore-aft impact tests are analyzed with FORTRAN IV software written using the formulas of this report.

Multianode microchannel array detectors for Space Shuttle imaging applications

NASA Technical Reports Server (NTRS)

Timothy, J. G.; Bybee, R. L.

1981-01-01

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric, photoncounting array detectors that have been developed and qualified specifically for use in space. MAMA detectors with formats as large as 256 x 1024 pixels are now in use or under construction for a variety of imaging and tracking applications. These photo-emissive detectors can be operated in a windowless configuration at extreme ultraviolet and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. The construction and modes-of-operation of the MAMA detectors are briefly described and the scientific objectives of a number of sounding rocket and Space Shuttle instruments utilizing these detectors are outlined. Performance characteristics of the MAMA detectors that are of fundamental importance for operation in the Space Shuttle environment are described and compared with those of the photo-conductive array detectors such as the CCDs and CIDs.

Design of a photovoltaic system for a southwest all-electric residence

NASA Astrophysics Data System (ADS)

Mehalick, E. M.; Obrien, G.; Tully, G. F.; Johnson, J.; Parker, J.

1980-04-01

The grid connected residential photovoltaic system for the Southwest is designed to meet both space conditioning requirements and all conventional electrical load requirements for an all-electric residence. The system is comprised of two major subsystems, the solar array and the power conditioning subsystem (PCS). An 8 kW peak photovoltaic array been designed for the house. The 93 square meters solar array uses a shingle solar cell module in a highly redundant series/parallel matrix. The photovoltaic generated power is supplied to a 10kVA power conversion subsystem which is controlled to track the solar array maximum power operating point and feed the 240 Vac output power directly to the house loads or back to the utility when excess power is generated. The photovoltaic power is isolated from the utility by a 15 kVA transformer. The house design and subsystem specifications are given in detail.

InAlAs/InGaAs avalanche photodiode arrays for free space optical communication.

PubMed

Ferraro, Mike S; Clark, William R; Rabinovich, William S; Mahon, Rita; Murphy, James L; Goetz, Peter G; Thomas, Linda M; Burris, Harris R; Moore, Christopher I; Waters, William D; Vaccaro, Kenneth; Krejca, Brian D

2015-11-01

In free space optical communication, photodetectors serve not only as communications receivers but also as position sensitive detectors (PSDs) for pointing, tracking, and stabilization. Typically, two separate detectors are utilized to perform these tasks, but recent advances in the fabrication and development of large-area, low-noise avalanche photodiode (APD) arrays have enabled these devices to be used both as PSDs and as communications receivers. This combined functionality allows for more flexibility and simplicity in optical system design without sacrificing the sensitivity and bandwidth performance of smaller, single-element data receivers. This work presents the development of APD arrays rated for bandwidths beyond 1 GHz with measured carrier ionization ratios of approximately 0.2 at moderate APD gains. We discuss the fabrication and characterization of three types of APD arrays along with their performance as high-speed photodetectors.

Linear laser diode arrays for improvement in optical disk recording

NASA Technical Reports Server (NTRS)

Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

1990-01-01

The development of individually addressable laser diode arrays for multitrack magneto-optic recorders for space stations is discussed. Three multi-element channeled substrate planar (CSP) arrays with output power greater than 30 mW with linear light vs current characteristics and stable single mode spectra were delivered to NASA. These devices have been used to demonstrate for the first time the simultaneous recording of eight data tracks on a 14-inch magneto-optic erasable disk. The yield of these devices is low, mainly due to non-uniformities inherent to the LPE growth that was used to fabricate them. The authors have recently developed the inverted CSP, based on the much more uniform MOCVD growth techniques, and have made low threshold quantum well arrays requiring about three times less current than the CSP to deliver 30 mW CW in a single spatial mode. The inverted CSP is very promising for use in space flight recorder applications.

DEVELOPMENT AND APPLICATION OF THE DORIAN (DOSE-RESPONSE INFORMATION ANALYSIS) SYSTEM

EPA Science Inventory

• Migration of ArrayTrack from the proprietary Oracle database to open source Postgres database.
• Making the public version of the ebKB available with provisions for soliciting input from collaborators and outside users.
• Continued development ...

• Target Tracking Onboard an Autonomous Underwater Vehicle: Determining Optimal Towed Array Heading in an Anisotropic Noise Field

  DTIC Science & Technology

  2007-09-01

  The geometry depicted in Figure 2-1 and defined in (9) governs the relationship between the two coordinate systems. We obtain the three-dimensional...node = ’ Unicorn ’ else if (v_id == 4) node = ’Macrura

• APL - North Pacific Acoustic Laboratory

  DTIC Science & Technology

  2015-03-04

  PhilSea10 cruise were spent in a series of upgrades and associated tests of the TCTD system. Electronic upgrades in conjunction with the manufacturers, ADM...amplitude at positions sufficiently removed from caustics . Mr. White computed eigenrays to all tracked upper array hydrophone positions relative to each

• Tracking microbial impact on crop production

  USDA-ARS?s Scientific Manuscript database

  One of the benefits of no-till systems is that activity of the soil microbial community increases. Producers gain an array of improvements in their production systems due to enhanced microbial functioning. For example, corn yield can increase approximately 25% with the same inputs with more microb...

• KSC-00padig059

  NASA Image and Video Library

  2000-10-31

  KENNEDY SPACE CENTER, FLA. -- Space Shuttle Endeavour and the Mobile Launcher Platform (MLP) start backing through the gate to Launch Pad 39B after a cracked cleat was discovered on the crawler-transporter. Workers near the pad (behind the crawler track) look at the cleats. The vehicle, which moves the MLP and Shuttle at about 1 mph, has a leveling system designed to keep the top of the Space Shuttle vertical while negotiating the 5 percent grade leading to the top of the pad. When the Shuttle-MLP are back on level ground, the crawler tracks will be inspected and the broken cleat repaired. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

• KSC00padig059

  NASA Image and Video Library

  2000-10-31

  KENNEDY SPACE CENTER, FLA. -- Space Shuttle Endeavour and the Mobile Launcher Platform (MLP) start backing through the gate to Launch Pad 39B after a cracked cleat was discovered on the crawler-transporter. Workers near the pad (behind the crawler track) look at the cleats. The vehicle, which moves the MLP and Shuttle at about 1 mph, has a leveling system designed to keep the top of the Space Shuttle vertical while negotiating the 5 percent grade leading to the top of the pad. When the Shuttle-MLP are back on level ground, the crawler tracks will be inspected and the broken cleat repaired. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

• Line drawing titled 'TDRS Spacecraft On-Orbit Configuration'

  NASA Technical Reports Server (NTRS)

  1988-01-01

  Line drawing titled 'TDRS Spacecraft On-Orbit Configuration' identifies the various tracking and data relay satellite (TDRS) components (solar arrays, C-Band antenna, K-Band antenna, space ground link (SGL) antenna, single access antennas, multiple access antenna, omni antenna, solar sail). A TDRS will be deployed during the STS-26 mission. Including the space shuttle, the TDRS will be equipped to support up to 26 user spacecraft simultaneously. It will provide two types of service: 1) multiple access which can relay data from as many as 20 low data rate (100 bits per second to 50 kilobits per second) user satellites simultaneously and; 2) single access which will provide two high data rate (to 300 megabits per second) communication relays. The TDRS is three-axis stabilizrd with the body fixed antennas pointing constantly at the Earth while the solar arrays track the Sun. TDR satellites do no processing of user traffic in either direction. Rather, they operate as 'bent pipe' repeaters,

• Tilted pillar array fabrication by the combination of proton beam writing and soft lithography for microfluidic cell capture Part 2: Image sequence analysis based evaluation and biological application.

  PubMed

  Járvás, Gábor; Varga, Tamás; Szigeti, Márton; Hajba, László; Fürjes, Péter; Rajta, István; Guttman, András

  2018-02-01

  As a continuation of our previously published work, this paper presents a detailed evaluation of a microfabricated cell capture device utilizing a doubly tilted micropillar array. The device was fabricated using a novel hybrid technology based on the combination of proton beam writing and conventional lithography techniques. Tilted pillars offer unique flow characteristics and support enhanced fluidic interaction for improved immunoaffinity based cell capture. The performance of the microdevice was evaluated by an image sequence analysis based in-house developed single-cell tracking system. Individual cell tracking allowed in-depth analysis of the cell-chip surface interaction mechanism from hydrodynamic point of view. Simulation results were validated by using the hybrid device and the optimized surface functionalization procedure. Finally, the cell capture capability of this new generation microdevice was demonstrated by efficiently arresting cells from a HT29 cell-line suspension. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

• Modified linear predictive coding approach for moving target tracking by Doppler radar

  NASA Astrophysics Data System (ADS)

  Ding, Yipeng; Lin, Xiaoyi; Sun, Ke-Hui; Xu, Xue-Mei; Liu, Xi-Yao

  2016-07-01

  Doppler radar is a cost-effective tool for moving target tracking, which can support a large range of civilian and military applications. A modified linear predictive coding (LPC) approach is proposed to increase the target localization accuracy of the Doppler radar. Based on the time-frequency analysis of the received echo, the proposed approach first real-time estimates the noise statistical parameters and constructs an adaptive filter to intelligently suppress the noise interference. Then, a linear predictive model is applied to extend the available data, which can help improve the resolution of the target localization result. Compared with the traditional LPC method, which empirically decides the extension data length, the proposed approach develops an error array to evaluate the prediction accuracy and thus, adjust the optimum extension data length intelligently. Finally, the prediction error array is superimposed with the predictor output to correct the prediction error. A series of experiments are conducted to illustrate the validity and performance of the proposed techniques.

• A Portable Ultrasonic Nondestructive Inspection System for Metal Matrix Composite Track Shoes

  NASA Astrophysics Data System (ADS)

  Mi, Bao; Zhao, Xiaoliang; Qian, Tao; Stevenson, Mark; Kwan, Chiman; Owens, Steven E.; Royer, Roger L.; Tittmann, Bernhard R.; Raju, Basavaraju B.

  2007-03-01

  Cast aluminum track shoes reinforced with metal matrix composite (MMC) inserts at heavy loading areas such as center splines and sprocket windows are light in weight, and can resist high temperature and wear. Various defects such as disbonds at the insert-substrate interface, cracks and porosity in the MMC layer, etc. can be introduced during the manufacturing process and/or in service. This paper presents a portable ultrasonic system to automatically inspect tank track shoes for disbond. Ultrasonic pulse/echo inspection has shown good reliability for disbond detection. A prototype sensor array fixture has been designed and fabricated to prove the feasibility. Good agreements between the sensor fixture results and ultrasonic C-scan images were obtained.

• Audio Tracking in Noisy Environments by Acoustic Map and Spectral Signature.

  PubMed

  Crocco, Marco; Martelli, Samuele; Trucco, Andrea; Zunino, Andrea; Murino, Vittorio

  2018-05-01

  A novel method is proposed for generic target tracking by audio measurements from a microphone array. To cope with noisy environments characterized by persistent and high energy interfering sources, a classification map (CM) based on spectral signatures is calculated by means of a machine learning algorithm. Next, the CM is combined with the acoustic map, describing the spatial distribution of sound energy, in order to obtain a cleaned joint map in which contributions from the disturbing sources are removed. A likelihood function is derived from this map and fed to a particle filter yielding the target location estimation on the acoustic image. The method is tested on two real environments, addressing both speaker and vehicle tracking. The comparison with a couple of trackers, relying on the acoustic map only, shows a sharp improvement in performance, paving the way to the application of audio tracking in real challenging environments.

• Fuzzy logic particle tracking velocimetry

  NASA Technical Reports Server (NTRS)

  Wernet, Mark P.

  1993-01-01

  Fuzzy logic has proven to be a simple and robust method for process control. Instead of requiring a complex model of the system, a user defined rule base is used to control the process. In this paper the principles of fuzzy logic control are applied to Particle Tracking Velocimetry (PTV). Two frames of digitally recorded, single exposure particle imagery are used as input. The fuzzy processor uses the local particle displacement information to determine the correct particle tracks. Fuzzy PTV is an improvement over traditional PTV techniques which typically require a sequence (greater than 2) of image frames for accurately tracking particles. The fuzzy processor executes in software on a PC without the use of specialized array or fuzzy logic processors. A pair of sample input images with roughly 300 particle images each, results in more than 200 velocity vectors in under 8 seconds of processing time.

• Adaptive DFT-based Interferometer Fringe Tracking

  NASA Technical Reports Server (NTRS)

  Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

  2004-01-01

  An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) observatory at Mt. Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three baselines of the Michelson stellar interferometer at IOTA. Based on sliding window discrete Fourier transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on off-line data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. The adaptive DFT-based tracking algorithm should be applicable to other systems where there is a need to detect or track a signal with an approximately constant-frequency carrier pulse.

• Direct investigation of collective phenomena in patterned Ising-like arrays using high-resolution Kerr microscopy

  NASA Astrophysics Data System (ADS)

  Fraleigh, Robert Douglas

  Magnetic systems with interacting ferromagnetic single-domain elements are a useful landscape to explore a wide range of fundamental and technological phenomena. In this dissertation, we consider a system of interacting ferromagnetic islands with perpendicular anisotropy. Islands are lithographically-defined to be single-domain and are arranged into large arrays with geometries that are geometrically frustrated and unfrustrated. We explore field-driven local and global magnetic switching behavior using a home-built diffraction-limited magneto-optical Kerr microscope wherein individual islands in each array are isolated, indexed, and tracked in the presence of an applied external field. Global and local switching behavior is directly accessed through analysis island switching fields in the presence of magnetic hysteresis loops. We first explore the considerations regarding lithographic definition of disconnected islands and deposition of Co/Pt multilayers with strong perpendicular anisotropy. The thickness and number of stacked Co/Pt bilayers as well as deposition method significantly affect the strength of perpendicular anisotropy. We find sputter deposition of a 8-stack bilayer of Co0.3 nm=Pt 1 nm optimizes strong perpendicular anisotropy with square hysteresis loops. Our experimental sample contains several sets of ordered arrays with varying geometry and inter-island spacing. Each island is single-domain with length scales amenable to Kerr imaging such that magnetic degrees of freedom are optically accessible. We next discuss the development, calibration, and operation of a home-built magneto-optical Kerr microscope. The Kerr microscope uses a xenon stabilized white light source, Glan-Thompson polarizers, and a 100x oil objective lens to illuminate a sample with linear polarized light. A cooled CCD camera receives the re ected light and transmits it to the computer in a sequence timed with the application of an external magnetic field. We use LabVIEW software to isolate, index, track, and extract intensity information and corresponding switching fields associated with individual islands in each array as a function of a magnetic field. We find the switching field distribution width is well-fit by a simple model comprising the sum of an array-independent contribution (interpreted as disorder-induced), and a term proportional to the maximum field the entire rest of the array could exert on a single island, i.e., in a fully polarized state. This supports the claim that disorder in these arrays is primarily a single-island property.

• Trace-transform invariants of tracks of high-velocity jets from the surface of tungsten droplets in the plasma flow

  NASA Astrophysics Data System (ADS)

  Gulyaev, P.; Jordan, V.; Gulyaev, I.; Dolmatov, A.

  2017-05-01

  The paper presents the analysis of the recorded tracks of high-velocity emission in the air-argon plasma flow during breaking up of tungsten microdroplets. This new physical effect of optical emission involves two stages. The first one includes thermionic emission of electrons from the surface of the melted tungsten droplet of 100-200 μm size and formation of the charged sphere of 3-5 mm diameter. After it reaches the breakdown electric potential, it collapses and produces a spherical shock wave and luminous radiation. The second stage includes previously unknown physical phenomenon of narrowly directed energy jet with velocity exceeding 4000 m/s from the surface of the tungsten droplet. The luminous spherical collapse and high-velocity jets were recorded using CMOS photo-array operating in a global shutter charge storage mode. Special features of the CMOS array scanning algorithm affect formation of distinctive signs of the recorded tracks, which stay invariant to trace transform (TT) with specific functional. The series of concentric circles were adopted as primitive object models (patterns) used in TT at the spherical collapse stage and linear segment of fixed thickness - at the high-velocity emission stage. The two invariants of the physical object, motion velocity and optical brightness distribution in the motion front, were adopted as desired identification features of tracks. The analytical expressions of the relation of 2D TT parameters and physical object motion invariants were obtained. The equations for spherical collapse stage correspond to Radon-Nikodym transform.

Real-time visual target tracking: two implementations of velocity-based smooth pursuit

NASA Astrophysics Data System (ADS)

Etienne-Cummings, Ralph; Longo, Paul; Van der Spiegel, Jan; Mueller, Paul

1995-06-01

Two systems for velocity-based visual target tracking are presented. The first two computational layers of both implementations are composed of VLSI photoreceptors (logarithmic compression) and edge detection (difference-of-Gaussians) arrays that mimic the outer-plexiform layer of mammalian retinas. The subsequent processing layers for measuring the target velocity and to realize smooth pursuit tracking are implemented in software and at the focal plane in the two versions, respectively. One implentation uses a hybrid of a PC and a silicon retina (39 X 38 pixels) operating at 333 frames/second. The software implementation of a real-time optical flow measurement algorithm is used to determine the target velocity, and a closed-loop control system zeroes the relative velocity of the target and retina. The second implementation is a single VLSI chip, which contains a linear array of photoreceptors, edge detectors and motion detectors at the focal plane. The closed-loop control system is also included on chip. This chip realizes all the computational properties of the hybrid system. The effects of background motion, target occlusion, and disappearance are studied as a function of retinal size and spatial distribution of the measured motion vectors (i.e. foveal/peripheral and diverging/converging measurement schemes). The hybrid system, which tested successfully, tracks targets moving as fast as 3 m/s at 1.3 meters from the camera and it can compensate for external arbitrary movements in its mounting platform. The single chip version, whose circuits tested successfully, can handle targets moving at 10 m/s.

Design study for LANDSAT D attitude control system

NASA Technical Reports Server (NTRS)

Iwens, R. P.; Bernier, G. E.; Hofstadter, R. F.

1976-01-01

A design and performance evaluation is presented for the LANDSAT D attitude control system (ACS). Control and configuration of the gimballed Ku-band antenna system for communication with the tracking and data relay satellite (TDRS). Control of the solar array drive considered part of the ACS is also addressed.

A Combined Laser-Communication and Imager for Microspacecraft (ACLAIM)

NASA Technical Reports Server (NTRS)

Hemmati, H.; Lesh, J.

1998-01-01

ACLAIM is a multi-function instrument consisting of a laser communication terminal and an imaging camera that share a common telescope. A single APS- (Active Pixel Sensor) based focal-plane-array is used to perform both the acquisition and tracking (for laser communication) and science imaging functions.

TRACE Observations of Changes in Coronal Hole Boundaries

DTIC Science & Technology

2010-02-13

predominate SXT •3 sP nngcr TRACK Observations of Changes in Coronal Hole Boundaries 145 active regions in CHs appear as anemone , characterized by a radial...array of loops formed by connections between the CH fields and the opposite polarity part of the active region. The anemone active regions are

Database of ground-based anemometer measurements of wake vortices at Kennedy Airport

DOT National Transportation Integrated Search

1997-07-01

A 7OO foot array of horizontal and vertical single-axis anemometers was installed at New York's Kennedy Airport on 30-foot poles under the approach to Runway 31R. Although the original purpose for the anemometers was to track the lateral position of ...

Thermal performance evaluation of the Northrop model NSC-01-0732 concentrating solar collector array at outdoor conditions. [Marshall Space Flight Center solar house test facility

NASA Technical Reports Server (NTRS)

1979-01-01

The thermal efficiency of the concentrating, tracking solar collector was tested after ten months of operation at the Marshall Space Flight Center solar house. The test procedures and results are presented.

Baseline antenna design for space exploration initiative

NASA Technical Reports Server (NTRS)

Chen, Y. L.; Nasir, M. A.; Lee, S. W.; Zaman, Afroz

1993-01-01

A key element of the future NASA Space Exploration Initiative (SEI) mission is the lunar and Mars telecommunication system. This system will provide voice, image, and data transmission to monitor unmanned missions to conduct experiments, and to provide radiometric data for navigation. In the later half of 1991, a study was conducted on antennas for the Mars Exploration Communication. Six antenna configurations were examined: three reflector and three phased array. The conclusion was that due to wide-angle scan requirement, and multiple simultaneous tracking beams, phased arrays are more suitable. For most part, this report studies phased array antenna designs for two different applications for Space Exploration Initiative. It also studies one design for a tri-reflector type antenna. These antennas will be based on a Mars orbiting satellite.

Space-Based Telemetry and Range Safety Project Ku-Band and Ka-Band Phased Array Antenna

NASA Technical Reports Server (NTRS)

Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.

2005-01-01

The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.

Ku- and Ka-Band Phased Array Antenna for the Space-Based Telemetry and Range Safety Project

NASA Technical Reports Server (NTRS)

Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.

2005-01-01

The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.

DESCANT--The DEuterated SCintillator Array for Neutron Tagging

NASA Astrophysics Data System (ADS)

Bildstein, Vinzenz; Garrett, P. E.; Bandyopadhay, D.; Bangay, J.; Bianco, L.; Demand, G.; Hadinia, B.; Leach, K. G.; Sumithrarachchi, C.; Wong, J.; Ashley, S. F.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Yates, S. W.; Vanhoy, J. R.; Ball, G. C.; Garnsworthy, A. B.; Hackman, G.; Pearson, C. J.; Sarazin, F.

2014-09-01

The DESCANT array at TRIUMF is designed to track neutrons from RIB experiments. DESCANT is composed of 70 close-packed deuterated organic liquid scintillators coupled to digital fast read-out ADC modules. This configuration will permit online pulse-shape discrimination between neutron and γ-ray events. The anisotropy of the n - d scattering will allow distinction of higher neutron multiplicities from scattering within the array and determination of the neutron energy spectrum directly from the pulse-height spectrum without using TOF. A prototype detector has been tested with monoenergetic neutrons at the accelerator laboratory of the University of Kentucky and a 24Mg(3He, n)26Si experiment has been performed with eight DESCANT detectors and two HPGe detectors. The results of the tests and the status of DESCANT will be presented.

High-Throughput Generation of Durable Droplet Arrays for Single-Cell Encapsulation, Culture, and Monitoring.

PubMed

Wu, Han; Chen, Xinlian; Gao, Xinghua; Zhang, Mengying; Wu, Jinbo; Wen, Weijia

2018-04-03

High-throughput measurements can be achieved using droplet-based assays. In this study, we exploited the principles of wetting behavior and capillarity to guide liquids sliding along a solid surface with hybrid wettability. Oil-covered droplet arrays with uniformly sized and regularly shaped picoliter droplets were successfully generated on hydrophilic-in-hydrophobic patterned substrates. More than ten thousand 31-pL droplets were generated in 5 s without any sophisticated instruments. Covering the droplet arrays with oil during generation not only isolated the droplets from each other but also effectively prevented droplet evaporation. The oil-covered droplet arrays could be stored for more than 2 days with less than 35% volume loss. Single microspheres, microbial cells, or mammalian cells were successfully captured in the droplets. We demonstrate that Escherichia coli could be encapsulated at a certain number (1-4) and cultured for 3 days in droplets. Cell population and morphology were dynamically tracked within individual droplets. Our droplet array generation method enables high-throughput processing and is facile, efficient, and low-cost; in addition, the prepared droplet arrays have enormous potential for applications in chemical and biological assays.

Fast disk array for image storage

NASA Astrophysics Data System (ADS)

Feng, Dan; Zhu, Zhichun; Jin, Hai; Zhang, Jiangling

1997-01-01

A fast disk array is designed for the large continuous image storage. It includes a high speed data architecture and the technology of data striping and organization on the disk array. The high speed data path which is constructed by two dual port RAM and some control circuit is configured to transfer data between a host system and a plurality of disk drives. The bandwidth can be more than 100 MB/s if the data path based on PCI (peripheral component interconnect). The organization of data stored on the disk array is similar to RAID 4. Data are striped on a plurality of disk, and each striping unit is equal to a track. I/O instructions are performed in parallel on the disk drives. An independent disk is used to store the parity information in the fast disk array architecture. By placing the parity generation circuit directly on the SCSI (or SCSI 2) bus, the parity information can be generated on the fly. It will affect little on the data writing in parallel on the other disks. The fast disk array architecture designed in the paper can meet the demands of the image storage.

McClellan PV system installation provides key lessons

NASA Astrophysics Data System (ADS)

Kauffman, W. R.

Design features and lessons learned in the installation of a 40 kWp solar cell array to supply power to a market on an airbase are outlined. The fixed-position modules interface with an inverter, ac and dc switchgear, controls, instrumentation, and an energy management system. The power control unit has a peak power tracking feature to maximize output from the 1142 cell modules. The inverter has functioned at over 98 percent efficiency near the 25 kW design range of the array. Moisture sealing to prevent ground faults was found necessary during the installation of the underground cabling.

The parallel lives of microtubules and cellulose microfibrils.

PubMed

Lloyd, Clive; Chan, Jordi

2008-12-01

A major breakthrough was the recent discovery that cellulose synthases really do move along the plasma membrane upon tracks provided by the underlying cortical microtubules. It emphasized the cytoplasmic contribution to cell wall organization. A growing number of microtubule-associated proteins has been identified and shown to affect the way that microtubules are ordered, with downstream effects on the pattern of growth. The dynamic properties of microtubules turn out to be key in understanding the behaviour of the global array and good progress has been made in deciphering the rules by which the array is self-organized.

Experimental evidence for the sensitivity of the air-shower radio signal to the longitudinal shower development

NASA Astrophysics Data System (ADS)

Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.

2012-04-01

We observe a correlation between the slope of radio lateral distributions and the mean muon pseudorapidity of 59 individual cosmic-ray-air-shower events. The radio lateral distributions are measured with LOPES, a digital radio interferometer colocated with the multidetector-air-shower array KASCADE-Grande, which includes a muon-tracking detector. The result proves experimentally that radio measurements are sensitive to the longitudinal development of cosmic-ray air showers. This is one of the main prerequisites for using radio arrays for ultra-high-energy particle physics and astrophysics.

Mission-Oriented Sensor Arrays and UAVs - a Case Study on Environmental Monitoring

NASA Astrophysics Data System (ADS)

Figueira, N. M.; Freire, I. L.; Trindade, O.; Simões, E.

2015-08-01

This paper presents a new concept of UAV mission design in geomatics, applied to the generation of thematic maps for a multitude of civilian and military applications. We discuss the architecture of Mission-Oriented Sensors Arrays (MOSA), proposed in Figueira et Al. (2013), aimed at splitting and decoupling the mission-oriented part of the system (non safety-critical hardware and software) from the aircraft control systems (safety-critical). As a case study, we present an environmental monitoring application for the automatic generation of thematic maps to track gunshot activity in conservation areas. The MOSA modeled for this application integrates information from a thermal camera and an on-the-ground microphone array. The use of microphone arrays technology is of particular interest in this paper. These arrays allow estimation of the direction-of-arrival (DOA) of the incoming sound waves. Information about events of interest is obtained by the fusion of the data provided by the microphone array, captured by the UAV, fused with information from the termal image processing. Preliminary results show the feasibility of the on-the-ground sound processing array and the simulation of the main processing module, to be embedded into an UAV in a future work. The main contributions of this paper are the proposed MOSA system, including concepts, models and architecture.

Dynamic Shape Capture of Free-Swimming Aquatic Life using Multi-view Stereo

NASA Astrophysics Data System (ADS)

Daily, David

2017-11-01

The reconstruction and tracking of swimming fish in the past has either been restricted to flumes, small volumes, or sparse point tracking in large tanks. The purpose of this research is to use an array of cameras to automatically track 50-100 points on the surface of a fish using the multi-view stereo computer vision technique. The method is non-invasive thus allowing the fish to swim freely in a large volume and to perform more advanced maneuvers such as rolling, darting, stopping, and reversing which have not been studied. The techniques for obtaining and processing the 3D kinematics and maneuvers of tuna, sharks, stingrays, and other species will be presented and compared. The National Aquarium and the Naval Undersea Warfare Center and.

The bipolar silicon microstrip detector: A proposal for a novel precision tracking device

NASA Astrophysics Data System (ADS)

Horisberger, R.

1990-03-01

It is proposed to combine the technology of fully depleted silicon microstrip detectors fabricated on n doped high resistivity silicon with the concept of the bipolar transistor. This is done by adding a n ++ doped region inside the normal p + implanted region of the reverse biased p + n diode. Teh resulting structure has amplifying properties and is referred to as bipolar pixel transistor. The simplest readout scheme of a bipolar pixel array by an aluminium strip bus leads to the bipolar microstrip detector. The bipolar pixel structure is expected to give a better signal-to-noise performance for the detection of minimum ionizing charged particle tracks than the normal silicon diode strip detector and therefore should allow in future the fabrication of thinner silicon detectors for precision tracking.

Bubble Transport through Micropillar Arrays

NASA Astrophysics Data System (ADS)

Lee, Kenneth; Savas, Omer

2012-11-01

In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

Preliminary Concept of Operations for the Deep Space Array-Based Network

NASA Astrophysics Data System (ADS)

Bagri, D. S.; Statman, J. I.

2004-05-01

The Deep Space Array-Based Network (DSAN) will be an array-based system, part of a greater than 1000 times increase in the downlink/telemetry capability of the Deep Space Network. The key function of the DSAN is provision of cost-effective, robust telemetry, tracking, and command services to the space missions of NASA and its international partners. This article presents an expanded approach to the use of an array-based system. Instead of using the array as an element in the existing Deep Space Network (DSN), relying to a large extent on the DSN infrastructure, we explore a broader departure from the current DSN, using fewer elements of the existing DSN, and establishing a more modern concept of operations. For example, the DSAN will have a single 24 x 7 monitor and control (M&C) facility, while the DSN has four 24 x 7 M&C facilities. The article gives the architecture of the DSAN and its operations philosophy. It also briefly describes the customer's view of operations, operations management, logistics, anomaly analysis, and reporting.

Sound source tracking device for telematic spatial sound field reproduction

NASA Astrophysics Data System (ADS)

Cardenas, Bruno

This research describes an algorithm that localizes sound sources for use in telematic applications. The localization algorithm is based on amplitude differences between various channels of a microphone array of directional shotgun microphones. The amplitude differences will be used to locate multiple performers and reproduce their voices, which were recorded at close distance with lavalier microphones, spatially corrected using a loudspeaker rendering system. In order to track multiple sound sources in parallel the information gained from the lavalier microphones will be utilized to estimate the signal-to-noise ratio between each performer and the concurrent performers.

Reduced complexity of multi-track joint 2-D Viterbi detectors for bit-patterned media recording channel

NASA Astrophysics Data System (ADS)

Myint, L. M. M.; Warisarn, C.

2017-05-01

Two-dimensional (2-D) interference is one of the prominent challenges in ultra-high density recording system such as bit patterned media recording (BPMR). The multi-track joint 2-D detection technique with the help of the array-head reading can tackle this problem effectively by jointly processing the multiple readback signals from the adjacent tracks. Moreover, it can robustly alleviate the impairments due to track mis-registration (TMR) and media noise. However, the computational complexity of such detectors is normally too high and hard to implement in a reality, even for a few multiple tracks. Therefore, in this paper, we mainly focus on reducing the complexity of multi-track joint 2-D Viterbi detector without paying a large penalty in terms of the performance. We propose a simplified multi-track joint 2-D Viterbi detector with a manageable complexity level for the BPMR's multi-track multi-head (MTMH) system. In the proposed method, the complexity of detector's trellis is reduced with the help of the joint-track equalization method which employs 1-D equalizers and 2-D generalized partial response (GPR) target. Moreover, we also examine the performance of a full-fledged multi-track joint 2-D detector and the conventional 2-D detection. The results show that the simplified detector can perform close to the full-fledge detector, especially when the system faces high media noise, with the significant low complexity.

Operation of Direct Drive Systems: Experiments in Peak Power Tracking and Multi-Thruster Control

NASA Technical Reports Server (NTRS)

Snyder, John Steven; Brophy, John R.

2013-01-01

Direct-drive power and propulsion systems have the potential to significantly reduce the mass of high-power solar electric propulsion spacecraft, among other advantages. Recent experimental direct-drive work has significantly mitigated or retired the technical risks associated with single-thruster operation, so attention is now moving toward systems-level areas of interest. One of those areas is the use of a Hall thruster system as a peak power tracker to fully use the available power from a solar array. A simple and elegant control based on the incremental conductance method, enhanced by combining it with the unique properties of Hall thruster systems, is derived here and it is shown to track peak solar array power very well. Another area of interest is multi-thruster operation and control. Dualthruster operation was investigated in a parallel electrical configuration, with both thrusters operating from discharge power provided by a single solar array. Startup and shutdown sequences are discussed, and it is shown that multi-thruster operation and control is as simple as for a single thruster. Some system architectures require operation of multiple cathodes while they are electrically connected together. Four different methods to control the discharge current emitted by individual cathodes in this configuration are investigated, with cathode flow rate control appearing to be advantageous. Dual-parallel thruster operation with equal cathode current sharing at total powers up to 10 kW is presented.

Influence of resonant transducer variations on long range guided wave monitoring of rail track

NASA Astrophysics Data System (ADS)

Loveday, Philip W.; Long, Craig S.

2016-02-01

The ability of certain guided wave modes to propagate long distances in continuously welded rail track is exploited in permanently installed monitoring systems. Previous work demonstrated that reflections from thermite welds could be measured at distances of the order of 1 km from a transducer array. The availability of numerous thermite welds is useful during the development of a monitoring system as real defects are not available. Measurements of reflections from welds were performed over an eleven month period with two permanently installed transducers. Phased array processing was performed and the true location of a weld is indicated by a strong reflection but there is generally also a smaller, spurious replica reflection, at the same distance but in the incorrect direction. In addition, the relative reflection from different welds appears to change over time. The influence of differences between the two resonant transducers was investigated using a model. It was found that estimating the attenuation in either direction and scaling the reflections in either direction decreased the variability in the reflection measurements. Transducer interaction effects, where the transducer closer to the weld records a greater reflection than the second transducer were observed and can be used to determine the direction of a weld. This feature was used to demonstrate a simple alternative to phased array processing that can be used with resonant transducers.

Introducing medical students to careers in medical education: the student track at an annual medical education conference.

PubMed

Blatt, Benjamin; Plack, Margaret; Suzuki, Mari; Arepalli, Sruthi; Schroth, Scott; Stagnaro-Green, Alex

2013-08-01

Few avenues exist to familiarize medical students with careers as clinician-educators, and the clinician-educator career pathway has not been well defined. In this article, the authors describe how they integrated a career-oriented student track into the 2011 Northeast Group on Educational Affairs (NEGEA) annual retreat to introduce students to careers in medical education. Annual education conferences are principal sources of educational scholarship, networking, collaboration, and information sharing; as such, they represent attractive venues for early exposure to the culture of medical education. The authors' goal in creating the NEGEA conference student track was to excite students about careers in medical education by providing them with an array of opportunities for active involvement in both student-specific and general conference activities.The authors draw from their experience to provide a guide for recruiting student participants to career-building student tracks. They also offer a guide for developing future student tracks, based on their experience and grounded in social cognitive career theory. Although their focus is on medical education, they believe these guides will be useful for educators planning a conference-based student track in any field.

A full-parallax 3D display with restricted viewing zone tracking viewer's eye

NASA Astrophysics Data System (ADS)

Beppu, Naoto; Yendo, Tomohiro

2015-03-01

The Three-Dimensional (3D) vision became widely known as familiar imaging technique now. The 3D display has been put into practical use in various fields, such as entertainment and medical fields. Development of 3D display technology will play an important role in a wide range of fields. There are various ways to the method of displaying 3D image. There is one of the methods that showing 3D image method to use the ray reproduction and we focused on it. This method needs many viewpoint images when achieve a full-parallax because this method display different viewpoint image depending on the viewpoint. We proposed to reduce wasteful rays by limiting projector's ray emitted to around only viewer using a spinning mirror, and to increase effectiveness of display device to achieve a full-parallax 3D display. We propose a method by using a tracking viewer's eye, a high-speed projector, a rotating mirror that tracking viewer (a spinning mirror), a concave mirror array having the different vertical slope arranged circumferentially (a concave mirror array), a cylindrical mirror. About proposed method in simulation, we confirmed the scanning range and the locus of the movement in the horizontal direction of the ray. In addition, we confirmed the switching of the viewpoints and convergence performance in the vertical direction of rays. Therefore, we confirmed that it is possible to realize a full-parallax.

SU-F-T-458: Tracking Trends of TG-142 Parameters Via Analysis of Data Recorded by 2D Chamber Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexandrian, A; Kabat, C; Defoor, D

Purpose: With increasing QA demands of medical physicists in clinical radiation oncology, the need for an effective method of tracking clinical data has become paramount. A tool was produced which scans through data automatically recorded by a 2D chamber array and extracts relevant information recommended by TG-142. Using this extracted information a timely and comprehensive analysis of QA parameters can be easily performed enabling efficient monthly checks on multiple linear accelerators simultaneously. Methods: A PTW STARCHECK chamber array was used to record several months of beam outputs from two Varian 2100 series linear accelerators and a Varian NovalisTx−. In conjunctionmore » with the chamber array, a beam quality phantom was used to simultaneously to determine beam quality. A minimalist GUI was created in MatLab that allows a user to set the file path of the data for each modality to be analyzed. These file paths are recorded to a MatLab structure and then subsequently accessed by a script written in Python (version 3.5.1) which then extracts values required to perform monthly checks as outlined by recommendations from TG-142. The script incorporates calculations to determine if the values recorded by the chamber array fall within an acceptable threshold. Results: Values obtained by the script are written to a spreadsheet where results can be easily viewed and annotated with a “pass” or “fail” and saved for further analysis. In addition to creating a new scheme for reviewing monthly checks, this application allows for able to succinctly store data for follow up analysis. Conclusion: By utilizing this tool, parameters recommended by TG-142 for multiple linear accelerators can be rapidly obtained and analyzed which can be used for evaluation of monthly checks.« less

Digestion proteomics: tracking lactoferrin truncation and peptide release during simulated gastric digestion.

PubMed

Grosvenor, Anita J; Haigh, Brendan J; Dyer, Jolon M

2014-11-01

The extent to which nutritional and functional benefit is derived from proteins in food is related to its breakdown and digestion in the body after consumption. Further, detailed information about food protein truncation during digestion is critical to understanding and optimising the availability of bioactives, in controlling and limiting allergen release, and in minimising or monitoring the effects of processing and food preparation. However, tracking the complex array of products formed during the digestion of proteins is not easily accomplished using classical proteomics. We here present and develop a novel proteomic approach using isobaric labelling to mapping and tracking protein truncation and peptide release during simulated gastric digestion, using bovine lactoferrin as a model food protein. The relative abundance of related peptides was tracked throughout a digestion time course, and the effect of pasteurisation on peptide release assessed. The new approach to food digestion proteomics developed here therefore appears to be highly suitable not only for tracking the truncation and relative abundance of released peptides during gastric digestion, but also for determining the effects of protein modification on digestibility and potential bioavailability.

Improving maximum power point tracking of partially shaded photovoltaic system by using IPSO-BELBIC

NASA Astrophysics Data System (ADS)

Al-Alim El-Garhy, M. Abd; Mubarak, R. I.; El-Bably, M.

2017-08-01

Solar photovoltaic (PV) arrays in remote applications are often related to the rapid changes in the partial shading pattern. Rapid changes of the partial shading pattern make the tracking of maximum power point (MPP) of the global peak through the local ones too difficult. An essential need to make a fast and efficient algorithm to detect the peaks values which always vary as the sun irradiance changes. This paper presents two algorithms based on the improved particle swarm optimization technique one of them with PID controller (IPSO-PID), and the other one with Brain Emotional Learning Based Intelligent Controller (IPSO-BELBIC). These techniques improve the maximum power point (MPP) tracking capabilities for photovoltaic (PV) system under partial shading circumstances. The main aim of these improved algorithms is to accelerate the velocity of IPSO to reach to (MPP) and increase its efficiency. These algorithms also improve the tracking time under complex irradiance conditions. Based on these conditions, the tracking time of these presented techniques improves to 2 msec, with an efficiency of 100%.

Assessment of laser tracking and data transfer for underwater optical communications

NASA Astrophysics Data System (ADS)

Watson, Malcolm A.; Blanchard, Paul M.; Stace, Chris; Bhogul, Priya K.; White, Henry J.; Kelly, Anthony E.; Watson, Scott; Valyrakis, Manousos; Najda, Stephen P.; Marona, Lucja; Perlin, Piotr

2014-10-01

We report on an investigation into optical alignment and tracking for high bandwidth, laser-based underwater optical communication links. Link acquisition approaches (including scanning of narrow laser beams versus a wide-angle `beacon' approach) for different underwater laser-based communications scenarios are discussed. An underwater laserbased tracking system was tested in a large water flume facility using water whose scattering properties resembled that of a turbid coastal or harbour region. The lasers used were state-of-the-art, temperature-controlled, high modulation bandwidth gallium nitride (GaN) devices. These operate at blue wavelengths and can achieve powers up to ~100 mW. The tracking performance and characteristics of the system were studied as the light-scattering properties of the water were increased using commercial antacid (Maalox) solution, and the results are reported here. Optical tracking is expected to be possible even in high scattering water environments, assuming better components are developed commercially; in particular, more sensitive detector arrays. High speed data transmission using underwater optical links, based on blue light sources, is also reported.

Lateral distributions of EAS muons (Eμ > 800 MeV) measured with the KASCADE-Grande Muon Tracking Detector in the primary energy range 1016 -1017 eV

NASA Astrophysics Data System (ADS)

Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Fuchs, B.; Fuhrmann, D.; Gherghel-Lascu, A.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Zabierowski, J.

2015-05-01

The KASCADE-Grande large area (128 m2) Muon Tracking Detector has been built with the aim to identify muons ( Eμthr = 800 MeV) in Extensive Air Showers by track measurements under 18 r.l. shielding. This detector provides high-accuracy angular information (approx. 0.3 °) for muons up to 700 m distance from the shower core. In this work we present the lateral density distributions of muons in EAS measured with the Muon Tracking Detector of the KASCADE-Grande experiment. The density is calculated by counting muon tracks in a muon-to-shower-axis distance range from 100 m to 610 m from showers with reconstructed energy of 1016 -1017 eV and zenith angle θ < 18 ° . In the distance range covered by the experiment, these distributions are well described by functions phenomenologically determined already in the fifties (of the last century) by Greisen. They are compared also with the distributions obtained with the KASCADE scintillator array (Eμthr = 230 MeV) and with distributions obtained using simulated showers.

MW 08-multi-beam air and surface surveillance radar

NASA Astrophysics Data System (ADS)

1989-09-01

Signal of the Netherlands has developed and is marketing the MW 08, a 3-D radar to be used for short to medium range surveillance, target acquisition, and tracking. MW 08 is a fully automated detecting and tracking radar. It is designed to counter threats from aircraft and low flying antiship missiles. It can also deal with the high level missile threat. MW 08 operates in the 5 cm band using one antenna for both transmitting and receiving. The antenna is an array, consisting of 8 stripline antennas. The received radar energy is processed by 8 receiver channels. These channels come together in the beam forming network, in which 8 virtual beams are formed. From this beam pattern, 6 beams are used for the elevation coverage of 0-70 degrees. MW 08's output signals of the beam former are further handled by FFT and plot processors for target speed information, clutter rejection, and jamming suppression. A general purpose computer handles target track initiation, and tracking. Tracking data are transferred to the command and control systems with 3-D target information for fastest possible lockon.

A restraint-free small animal SPECT imaging system with motion tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisenberger, A.G.; Gleason, S.S.; Goddard, J.

2005-06-01

We report on an approach toward the development of a high-resolution single photon emission computed tomography (SPECT) system to image the biodistribution of radiolabeled tracers such as Tc-99m and I-125 in unrestrained/unanesthetized mice. An infrared (IR)-based position tracking apparatus has been developed and integrated into a SPECT gantry. The tracking system is designed to measure the spatial position of a mouse's head at a rate of 10-15 frames per second with submillimeter accuracy. The high-resolution, gamma imaging detectors are based on pixellated NaI(Tl) crystal scintillator arrays, position-sensitive photomultiplier tubes, and novel readout circuitry requiring fewer analog-digital converter (ADC) channels whilemore » retaining high spatial resolution. Two SPECT gamma camera detector heads based upon position-sensitive photomultiplier tubes have been built and installed onto the gantry. The IR landmark-based pose measurement and tracking system is under development to provide animal position data during a SPECT scan. The animal position and orientation data acquired by the tracking system will be used for motion correction during the tomographic image reconstruction.« less

An Adaptive 6-DOF Tracking Method by Hybrid Sensing for Ultrasonic Endoscopes

PubMed Central

Du, Chengyang; Chen, Xiaodong; Wang, Yi; Li, Junwei; Yu, Daoyin

2014-01-01

In this paper, a novel hybrid sensing method for tracking an ultrasonic endoscope within the gastrointestinal (GI) track is presented, and the prototype of the tracking system is also developed. We implement 6-DOF localization by sensing integration and information fusion. On the hardware level, a tri-axis gyroscope and accelerometer, and a magnetic angular rate and gravity (MARG) sensor array are attached at the end of endoscopes, and three symmetric cylindrical coils are placed around patients' abdomens. On the algorithm level, an adaptive fast quaternion convergence (AFQC) algorithm is introduced to determine the orientation by fusing inertial/magnetic measurements, in which the effects of magnetic disturbance and acceleration are estimated to gain an adaptive convergence output. A simplified electro-magnetic tracking (SEMT) algorithm for dimensional position is also implemented, which can easily integrate the AFQC's results and magnetic measurements. Subsequently, the average position error is under 0.3 cm by reasonable setting, and the average orientation error is 1° without noise. If magnetic disturbance or acceleration exists, the average orientation error can be controlled to less than 3.5°. PMID:24915179

The mechanism of color change in the neon tetra fish: a light-induced tunable photonic crystal array.

PubMed

Gur, Dvir; Palmer, Benjamin A; Leshem, Ben; Oron, Dan; Fratzl, Peter; Weiner, Steve; Addadi, Lia

2015-10-12

The fresh water fish neon tetra has the ability to change the structural color of its lateral stripe in response to a change in the light conditions, from blue-green in the light-adapted state to indigo in the dark-adapted state. The colors are produced by constructive interference of light reflected from stacks of intracellular guanine crystals, forming tunable photonic crystal arrays. We have used micro X-ray diffraction to track in time distinct diffraction spots corresponding to individual crystal arrays within a single cell during the color change. We demonstrate that reversible variations in crystal tilt within individual arrays are responsible for the light-induced color variations. These results settle a long-standing debate between the two proposed models, the "Venetian blinds" model and the "accordion" model. The insight gained from this biogenic light-induced photonic tunable system may provide inspiration for the design of artificial optical tunable systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aircraft Wake Vortex Measurements at Denver International Airport

NASA Technical Reports Server (NTRS)

Dougherty, Robert P.; Wang, Frank Y.; Booth, Earl R.; Watts, Michael E.; Fenichel, Neil; D'Errico, Robert E.

2004-01-01

Airport capacity is constrained, in part, by spacing requirements associated with the wake vortex hazard. NASA's Wake Vortex Avoidance Project has a goal to establish the feasibility of reducing this spacing while maintaining safety. Passive acoustic phased array sensors, if shown to have operational potential, may aid in this effort by detecting and tracking the vortices. During August/September 2003, NASA and the USDOT sponsored a wake acoustics test at the Denver International Airport. The central instrument of the test was a large microphone phased array. This paper describes the test in general terms and gives an overview of the array hardware. It outlines one of the analysis techniques that is being applied to the data and gives sample results. The technique is able to clearly resolve the wake vortices of landing aircraft and measure their separation, height, and sinking rate. These observations permit an indirect estimate of the vortex circulation. The array also provides visualization of the vortex evolution, including the Crow instability.

Chronic intracortical microstimulation (ICMS) of cat sensory cortex using the Utah Intracortical Electrode Array.

PubMed

Rousche, P J; Normann, R A

1999-03-01

In an effort to assess the safety and efficacy of focal intracortical microstimulation (ICMS) of cerebral cortex with an array of penetrating electrodes as might be applied to a neuroprosthetic device to aid the deaf or blind, we have chronically implanted three trained cats in primary auditory cortex with the 100-electrode Utah Intracortical Electrode Array (UIEA). Eleven of the 100 electrodes were hard-wired to a percutaneous connector for chronic access. Prior to implant, cats were trained to "lever-press" in response to pure tone auditory stimulation. After implant, this behavior was transferred to "lever-presses" in response to current injections via single electrodes of the implanted arrays. Psychometric function curves relating injected charge level to the probability of response were obtained for stimulation of 22 separate electrodes in the three implanted cats. The average threshold charge/phase required for electrical stimulus detection in each cat was, 8.5, 8.6, and 11.6 nC/phase respectively, with a maximum charge/phase of 26 nC/phase and a minimum of 1.5 nC/phase thresholds were tracked for varying time intervals, and seven electrodes from two cats were tracked for up to 100 days. Electrodes were stimulated for no more than a few minutes each day. Neural recordings taken from the same electrodes before and after multiple electrical stimulation sessions were very similar in signal/noise ratio and in the number of recordable units, suggesting that the range of electrical stimulation levels used did not damage neurons in the vicinity of the electrodes. Although a few early implants failed, we conclude that ICMS of cerebral cortex to evoke a behavioral response can be achieved with the penetrating UIEA. Further experiments in support of a sensory cortical prosthesis based on ICMS are warranted.

Tracking in Real-Time Pyroclastic Flows at Soufriere Hills Volcano, Montserrat, by infrasonic array.

NASA Astrophysics Data System (ADS)

Ripepe, M.; de Angelis, S.; Lacanna, G.; Poggi, P.; Williams, C.

2008-12-01

Active volcanoes produce infrasonic airwaves, which provide valuable insight into the eruption dynamics and the level of volcanic activity. On open conduit volcanoes, infrasound can be used to monitor the gas overpressure in the magma and the degassing rate of active volcanic vents. On volcanoes characterized by dome growth, infrasound can also be generated by non-explosive sources related to dome collapses and pyroclastic flows. In March 2008, the Department of Earth Science (DST) of Firenze (Italy) in cooperation with Montserrat Volcano Observatory (MVO) has installed a small-aperture infrasonic array at a distance of ~3000 m from the dome of the Soufriere Hill Volcano (SHV). The array has an aperture of 200 m and a "star" geometry, with 3 satellite stations at 100 m distance from the receiving central station. Each element of the array is linked to the receiver station by fiber optics cable, and the signal is acquired with a resolution of 16 bits at a rate of 50 samples/sec. The data collected by the array are sent via a radio modem link to the MVO offices, on Montserrat, where they are archived and processed in real-time. Real-time location of infrasonic events are obtained and displayed on computer monitors for use in monitoring of volcanic activity. After a period of very low levels of activity, starting from the end of May 2008, SHV has produced several small explosions without any short-term precursory sign. Some of these events have generated ash plumes reaching up to a few thousands of meters above the sea level, and were accompanied by moderate-to-large size pyroclastic flows that descended the western flanks of the volcanic edifice. The array was able to detect and locate in real-time the clear infrasound associated both with the explosions and the pyroclastic flows. In the latter case, the array estimated the speed and the direction of the flux revealing the presence of several pulses within the same flow. The variable azimuth of the signal during the flow indicated a mean speed of 160-175 km/h. The ability to detect and track such events in a real-time fashion has a strong impact on understanding the dynamics of pyroclastic flow propagation as well as on monitoring operations and risk management in Montserrat.

A Double-Dissociation in Infants' Representations of Object Arrays

ERIC Educational Resources Information Center

Feigenson, L.

2005-01-01

Previous studies show that infants can compute either the total continuous extent (e.g. Clearfield, M.W., & Mix, K.S. (1999). Number versus contour length in infants' discrimination of small visual sets. Psychological Science, 10(5), 408-411; Feigenson, L., & Carey, S. (2003). Tracking individuals via object-files: evidence from infants' manual…

The 18th Aerospace Mechanisms Symposium

NASA Technical Reports Server (NTRS)

1984-01-01

Topics concerning aerospace mechanisms, their functional performance, and design specifications are presented. Discussed subjects include the design and development of release mechanisms, actuators, linear driver/rate controllers, antenna and appendage deployment systems, position control systems, and tracking mechanisms for antennas and solar arrays. Engine design, spaceborne experiments, and large space structure technology are also examined.

CMOS Active-Pixel Image Sensor With Intensity-Driven Readout

NASA Technical Reports Server (NTRS)

Langenbacher, Harry T.; Fossum, Eric R.; Kemeny, Sabrina

1996-01-01

Proposed complementary metal oxide/semiconductor (CMOS) integrated-circuit image sensor automatically provides readouts from pixels in order of decreasing illumination intensity. Sensor operated in integration mode. Particularly useful in number of image-sensing tasks, including diffractive laser range-finding, three-dimensional imaging, event-driven readout of sparse sensor arrays, and star tracking.

Comparison of Sewage and Animal Fecal Microbiomes by using Oligotyping Reveals Potential Human Fecal Indicators in Multiple Taxonomic Groups

EPA Science Inventory

Most DNA-based microbial source tracking (MST) approaches target host-associated organisms within the order Bacteroidales, but human and other animal gut microbiota contain an array of other taxonomic groups that might serve as indicators for sources of fecal pollution. High thr...

Brief Report: Circumscribed Attention in Young Children with Autism

ERIC Educational Resources Information Center

Sasson, Noah J.; Elison, Jed T.; Turner-Brown, Lauren M.; Dichter, Gabriel S.; Bodfish, James W.

2011-01-01

School-aged children and adolescents with autism demonstrate circumscribed attentional patterns to nonsocial aspects of complex visual arrays (Sasson et al. "2008"). The current study downward extended these findings to a sample of 2-5 year-olds with autism and 2-5 year-old typically developing children. Eye-tracking was used to quantify discrete…

Rotational band structure in Mg 32

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crawford, H. L.; Fallon, P.; Macchiavelli, A. O.

2016-03-01

There is significant evidence supporting the existence of deformed ground states within the neutron-rich N ≈ 20 neon, sodium, and magnesium isotopes that make up what is commonly called the “island of inversion.” However, the rotational band structures, which are a characteristic fingerprint of a rigid nonspherical shape, have yet to be observed. In this work, we report on a measurement and analysis of the yrast (lowest lying) rotational band in 32 Mg up to spin I = 6 + produced in a two-step projectile fragmentation reaction and observed using the state-of-the-art γ -ray tracking detector array, GRETINA ( γmore » -ray energy tracking in-beam nuclear array). Large-scale shell-model calculations using the SDPF-U-MIX effective interaction show excellent agreement with the new data. Moreover, a theoretical analysis of the spectrum of rotational states as a function of the pairing gap, together with cranked-shell-model calculations, provides intriguing evidence for a reduction in pairing correlations with increased angular momentum, also in line with the shell-model results.« less

The IceCube Neutrino Observatory, the Pierre Auger Observatory and the Telescope Array: Joint Contribution to the 34th International Cosmic Ray Conference (ICRC 2015)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aartsen, M.G.; et al.

2015-11-06

We have conducted three searches for correlations between ultra-high energy cosmic rays detected by the Telescope Array and the Pierre Auger Observatory, and high-energy neutrino candidate events from IceCube. Two cross-correlation analyses with UHECRs are done: one with 39 cascades from the IceCube `high-energy starting events' sample and the other with 16 high-energy `track events'. The angular separation between the arrival directions of neutrinos and UHECRs is scanned over. The same events are also used in a separate search using a maximum likelihood approach, after the neutrino arrival directions are stacked. To estimate the significance we assume UHECR magnetic deflections to be inversely proportional to their energy, with valuesmore » $$3^\\circ$$, $$6^\\circ$$ and $$9^\\circ$$ at 100 EeV to allow for the uncertainties on the magnetic field strength and UHECR charge. A similar analysis is performed on stacked UHECR arrival directions and the IceCube sample of through-going muon track events which were optimized for neutrino point-source searches.« less

Biomimetic model systems of rigid hair beds: Part II - Experiment

NASA Astrophysics Data System (ADS)

Jammalamadaka, Mani S. S.; Hood, Kaitlyn; Hosoi, Anette

2017-11-01

Crustaceans - such as lobsters, crabs and stomapods - have hairy appendages that they use to recognize and track odorants in the surrounding fluid. An array of rigid hairs impedes flow at different rates depending on the spacing between hairs and the Reynolds number, Re. At larger Reynolds number (Re>1), fluid travels through the hairs rather than around them, a phenomenon called leakiness. Crustaceans flick their appendages at different speeds in order to manipulate the leakiness between the hairs, allowing the hairs to either detect the odors in a sample of fluid or collect a new sample. Theoretical and numerical studies predict that there is a fast flow region near the hairs that moves closer to the hairs as Re increases. Here, we test this theory experimentally. We 3D printed rigid hairs with an aspect ratio of 30:1 in rectangular arrays with different hair packing fractions. We custom built an experimental setup which establishes poiseuille flow at intermediate Re, Re <=200. We track the flow dynamics through the hair beds using tracer particles and Particle Imaging Velocimetry. We will then compare the modelling predictions with the experimental outcomes.

Study of Running Stability in Side-Suspended HTS-PMG Maglev Circular Line System

NASA Astrophysics Data System (ADS)

Zhou, Dajin; Zhao, Lifeng; Li, Linbo; Cui, Chenyu; Hsieh, Chang-Chun; Zhang, Yong; Guo, Jianqiang; Zhao, Yong

2017-07-01

A research on stability of the side-suspended HTS-PMG maglev circular line system is carried out through simulation experiment. The results show that the maglev vehicle will gradually get close to the track surface during acceleration under the action of centrifugal force, leading to decay of guidance force and occurrence of vertical eccentric motion. In case of linear array of YBa2Cu3O7-x (YBCO) bulks, the guidance force will be changed with the decreasing of the levitation gap. It can be suppressed through the complex arrangement of YBCO bulks. Fortunately, triangle array of YBCO bulks can effectively keep the guidance force constant and realize stable running during accelerating process of the prototype vehicle. Based on the research on stability of side-suspended maglev vehicle, a side-suspended PMG circular test track with diameter of 6.5 m and circumference of 20.4 m is successfully designed and established, enabling the prototype vehicle to run stably at up to 82.5 km/h under open atmosphere (9.6 × 104 Pa).

A novel approach of an absolute coding pattern based on Hamiltonian graph

NASA Astrophysics Data System (ADS)

Wang, Ya'nan; Wang, Huawei; Hao, Fusheng; Liu, Liqiang

2017-02-01

In this paper, a novel approach of an optical type absolute rotary encoder coding pattern is presented. The concept is based on the principle of the absolute encoder to find out a unique sequence that ensures an unambiguous shaft position of any angular. We design a single-ring and a n-by-2 matrix absolute encoder coding pattern by using the variations of Hamiltonian graph principle. 12 encoding bits is used in the single-ring by a linear array CCD to achieve an 1080-position cycle encoding. Besides, a 2-by-2 matrix is used as an unit in the 2-track disk to achieve a 16-bits encoding pattern by using an area array CCD sensor (as a sample). Finally, a higher resolution can be gained by an electronic subdivision of the signals. Compared with the conventional gray or binary code pattern (for a 2n resolution), this new pattern has a higher resolution (2n*n) with less coding tracks, which means the new pattern can lead to a smaller encoder, which is essential in the industrial production.

Proposed Array-based Deep Space Network for NASA

NASA Technical Reports Server (NTRS)

Bagri, Durgadas S.; Statman, Joseph I.; Gatti, Mark S.

2007-01-01

The current assets of the Deep Space Network (DSN) of the National Aeronautics and Space Administration (NASA), especially the 70-m antennas, are aging and becoming less reliable. Furthermore, they are expensive to operate and difficult to upgrade for operation at Ka-band (321 GHz). Replacing them with comparable monolithic large antennas would be expensive. On the other hand, implementation of similar high-sensitivity assets can be achieved economically using an array-based architecture, where sensitivity is measured by G/T, the ratio of antenna gain to system temperature. An array-based architecture would also provide flexibility in operations and allow for easy addition of more G/T whenever required. Therefore, an array-based plan of the next-generation DSN for NASA has been proposed. The DSN array would provide more flexible downlink capability compared to the current DSN for robust telemetry, tracking and command services to the space missions of NASA and its international partners in a cost effective way. Instead of using the array as an element of the DSN and relying on the existing concept of operation, we explore a broader departure in establishing a more modern concept of operations to reduce the operations costs. This paper presents the array-based architecture for the next generation DSN. It includes system block diagram, operations philosophy, user's view of operations, operations management, and logistics like maintenance philosophy and anomaly analysis and reporting. To develop the various required technologies and understand the logistics of building the array-based lowcost system, a breadboard array of three antennas has been built. This paper briefly describes the breadboard array system and its performance.

Control strategy of grid-connected photovoltaic generation system based on GMPPT method

NASA Astrophysics Data System (ADS)

Wang, Zhongfeng; Zhang, Xuyang; Hu, Bo; Liu, Jun; Li, Ligang; Gu, Yongqiang; Zhou, Bowen

2018-02-01

There are multiple local maximum power points when photovoltaic (PV) array runs under partial shading condition (PSC).However, the traditional maximum power point tracking (MPPT) algorithm might be easily trapped in local maximum power points (MPPs) and cannot find the global maximum power point (GMPP). To solve such problem, a global maximum power point tracking method (GMPPT) is improved, combined with traditional MPPT method and particle swarm optimization (PSO) algorithm. Under different operating conditions of PV cells, different tracking algorithms are used. When the environment changes, the improved PSO algorithm is adopted to realize the global optimal search, and the variable step incremental conductance (INC) method is adopted to achieve MPPT in optimal local location. Based on the simulation model of the PV grid system built in Matlab/Simulink, comparative analysis of the tracking effect of MPPT by the proposed control algorithm and the traditional MPPT method under the uniform solar condition and PSC, validate the correctness, feasibility and effectiveness of the proposed control strategy.

The Extended-Image Tracking Technique Based on the Maximum Likelihood Estimation

NASA Technical Reports Server (NTRS)

Tsou, Haiping; Yan, Tsun-Yee

2000-01-01

This paper describes an extended-image tracking technique based on the maximum likelihood estimation. The target image is assume to have a known profile covering more than one element of a focal plane detector array. It is assumed that the relative position between the imager and the target is changing with time and the received target image has each of its pixels disturbed by an independent additive white Gaussian noise. When a rotation-invariant movement between imager and target is considered, the maximum likelihood based image tracking technique described in this paper is a closed-loop structure capable of providing iterative update of the movement estimate by calculating the loop feedback signals from a weighted correlation between the currently received target image and the previously estimated reference image in the transform domain. The movement estimate is then used to direct the imager to closely follow the moving target. This image tracking technique has many potential applications, including free-space optical communications and astronomy where accurate and stabilized optical pointing is essential.

Long-term temporal tracking of speech rate affects spoken-word recognition.

PubMed

Baese-Berk, Melissa M; Heffner, Christopher C; Dilley, Laura C; Pitt, Mark A; Morrill, Tuuli H; McAuley, J Devin

2014-08-01

Humans unconsciously track a wide array of distributional characteristics in their sensory environment. Recent research in spoken-language processing has demonstrated that the speech rate surrounding a target region within an utterance influences which words, and how many words, listeners hear later in that utterance. On the basis of hypotheses that listeners track timing information in speech over long timescales, we investigated the possibility that the perception of words is sensitive to speech rate over such a timescale (e.g., an extended conversation). Results demonstrated that listeners tracked variation in the overall pace of speech over an extended duration (analogous to that of a conversation that listeners might have outside the lab) and that this global speech rate influenced which words listeners reported hearing. The effects of speech rate became stronger over time. Our findings are consistent with the hypothesis that neural entrainment by speech occurs on multiple timescales, some lasting more than an hour. © The Author(s) 2014.

LEA Detection and Tracking Method for Color-Independent Visual-MIMO

PubMed Central

Kim, Jai-Eun; Kim, Ji-Won; Kim, Ki-Doo

2016-01-01

Communication performance in the color-independent visual-multiple input multiple output (visual-MIMO) technique is deteriorated by light emitting array (LEA) detection and tracking errors in the received image because the image sensor included in the camera must be used as the receiver in the visual-MIMO system. In this paper, in order to improve detection reliability, we first set up the color-space-based region of interest (ROI) in which an LEA is likely to be placed, and then use the Harris corner detection method. Next, we use Kalman filtering for robust tracking by predicting the most probable location of the LEA when the relative position between the camera and the LEA varies. In the last step of our proposed method, the perspective projection is used to correct the distorted image, which can improve the symbol decision accuracy. Finally, through numerical simulation, we show the possibility of robust detection and tracking of the LEA, which results in a symbol error rate (SER) performance improvement. PMID:27384563

LEA Detection and Tracking Method for Color-Independent Visual-MIMO.

PubMed

Kim, Jai-Eun; Kim, Ji-Won; Kim, Ki-Doo

2016-07-02

Communication performance in the color-independent visual-multiple input multiple output (visual-MIMO) technique is deteriorated by light emitting array (LEA) detection and tracking errors in the received image because the image sensor included in the camera must be used as the receiver in the visual-MIMO system. In this paper, in order to improve detection reliability, we first set up the color-space-based region of interest (ROI) in which an LEA is likely to be placed, and then use the Harris corner detection method. Next, we use Kalman filtering for robust tracking by predicting the most probable location of the LEA when the relative position between the camera and the LEA varies. In the last step of our proposed method, the perspective projection is used to correct the distorted image, which can improve the symbol decision accuracy. Finally, through numerical simulation, we show the possibility of robust detection and tracking of the LEA, which results in a symbol error rate (SER) performance improvement.

An active K/Ka-band antenna array for the NASA ACTS mobile terminal

NASA Technical Reports Server (NTRS)

Tulintseff, A.; Crist, R.; Densmore, Art; Sukamto, L.

1993-01-01

An active K/Ka-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz. Satellite tracking for the land-mobile vehicular antenna system involves 'mechanical dithering' of the antenna, where the antenna radiates a fixed beam 46 deg. above the horizon. The antenna is to transmit horizontal polarization and receive vertical polarization at 29.634 plus or minus 0.15 GHz and 19.914 plus or minus 0.15 GHz, respectively. The active array will provide a minimum of 22 dBW EIRP transmit power density and a -8 dB/K deg. receive sensitivity.

Automated control of linear constricted plasma source array

DOEpatents

Anders, Andre; Maschwitz, Peter A.

2000-01-01

An apparatus and method for controlling an array of constricted glow discharge chambers are disclosed. More particularly a linear array of constricted glow plasma sources whose polarity and geometry are set so that the contamination and energy of the ions discharged from the sources are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The quality of film along deposition "tracks" opposite the plasma sources can be measured and compared to desired absolute or relative values by optical and/or electrical sensors. Plasma quality can then be adjusted by adjusting the power current values, gas feed pressure/flow, gas mixtures or a combination of some or all of these to improve the match between the measured values and the desired values.

Search in 8 TeV proton-proton collisions with the MoEDAL monopole-trapping test array

NASA Astrophysics Data System (ADS)

Pinfold, J.; Soluk, R.; Lacarrère, D.; Katre, A.; Mermod, P.; Bendtz, K.; Milstead, D.

2014-06-01

The magnetic monopole appears in theories of spontaneous gauge symmetry breaking and its existence would explain the quantisation of electric charge. MoEDAL is the latest approved LHC experiment, designed to search directly for monopoles produced in high-energy collisions. It has now taken data for the first time. The MoEDAL detectors are based on two complementary techniques: nuclear-track detectors are sensitive to the high-ionisation signature expected from a monopole, and the magnetic monopole trapper (MMT) relies on the stopping and trapping of monopoles inside an aluminium array which is then analysed with a superconducting magnetometer. The first results obtained with the MoEDAL MMT test array deployed in 2012 are presented. This experiment probes monopoles carrying a multiple of the fundamental unit magnetic charge for the first time at the LHC.

Novel multireceiver communication systems configurations based on optimal estimation theory

NASA Technical Reports Server (NTRS)

Kumar, Rajendra

1992-01-01

A novel multireceiver configuration for carrier arraying and/or signal arraying is presented. The proposed configuration is obtained by formulating the carrier and/or signal arraying problem as an optimal estimation problem, and it consists of two stages. The first stage optimally estimates various phase processes received at different receivers with coupled phase-locked loops wherein the individual loops acquire and track their respective receivers' phase processes but are aided by each other in an optimal manner via LF error signals. The proposed configuration results in the minimization of the the effective radio loss at the combiner output, and thus maximization of energy per bit to noise power spectral density ratio is achieved. A novel adaptive algorithm for the estimator of the signal model parameters when these are not known a priori is also presented.

Adaptive ground implemented phase array

NASA Technical Reports Server (NTRS)

Spearing, R. E.

1973-01-01

The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.

An Artificial Nose Based on Microcantilever Array Sensors

NASA Astrophysics Data System (ADS)

Lang, H. P.; Ramseyer, J. P.; Grange, W.; Braun, T.; Schmid, D.; Hunziker, P.; Jung, C.; Hegner, M.; Gerber, C.

2007-03-01

We used microfabricated cantilever array sensors for an artificial nose setup. Each cantilever is coated on its top surface with a polymer layer. Volatile gaseous analytes are detected by tracking the diffusion process of the molecules into the polymer layers, resulting in swelling of the polymer layers and therewith bending of the cantilevers. From the bending pattern of all cantilevers in the array, a characteristic 'fingerprint' of the analyte is obtained, which is evaluated using principal component analysis. In a flow of dry nitrogen gas, the bending of the cantilevers is reverted to its initial state before exposure to the analyte, which allows reversible and reproducible operation of the sensor. We show examples of detection of solvents, perfume essences and beverage flavors. In a medical application, the setup provides indication of presence of diseases in patient's breath samples.

The turbulent life of juvenile icebergs: Observations from an array of high-rate time-lapse cameras in LeConte Bay, Alaska

NASA Astrophysics Data System (ADS)

Kienholz, C.; Amundson, J. M.; Jackson, R. H.; Motyka, R. J.; Nash, J. D.; Sutherland, D.

2017-12-01

Tidewater glacier behavior is driven by poorly understood processes occurring at the ice-ocean interface, including sedimentation and erosion, iceberg calving, and submarine melting. These processes are inherently difficult to observe, calling for innovative field techniques and numerical models. As part of a multi-year field effort to constrain ocean-glacier heat and mass exchange, we deployed an array of high-rate time-lapse cameras (sampling intervals between 15 seconds and 2 minutes) to monitor the terminus of LeConte Glacier and its proglacial fjord. The camera array has operated continuously for more than a year. Our high sampling rates enable tracking of iceberg motion with optical flow algorithms, which have been used widely in computer vision but less so in glaciology and oceanography. Such algorithms track individual features (e.g., corners of icebergs), which is ideal for iceberg-rich fjords, where motion can vary substantially over short temporal and spatial scales (e.g., due to complex surface currents or different iceberg sizes). We process our data to quantify subdaily to seasonal patterns in surface currents and relate them to forcing from tides, wind, and glacier runoff. Flow is most variable close to the glacier terminus due to frequent calving events and turbulent plume dynamics. Farther down fjord, more consistent patterns emerge, driven by tides, wind, and runoff and altered by fjord geometry. Our tracking results compare favorably to and complement our Acoustic Doppler Current Profiler measurements from boats and moorings. Given their high spatial and temporal resolution, our observations will place important surface constraints on forthcoming hydrodynamic modeling efforts. The deployment of the cameras in a harsh environment and the corresponding image processing provided an opportunity to test hardware and software thoroughly, which will prove useful for similar systems at other glaciers.

Plume-tracking robots: a new application of chemical sensors.

PubMed

Ishid, H; Nakamoto, T; Moriizumi, T; Kikas, T; Janata, J

2001-04-01

Many animals have the ability to search for odor sources by tracking their plumes. Some of the key features of this search behavior have been successfully transferred to robot platforms, although the capabilities of animals are still beyond the current level of sensor technologies. The examples described in this paper are (1) incorporating into a wheeled robot the upwind surges and casting used by moths in tracking pheromone plumes, (2) extracting useful information from the response patterns of a chemical sensor array patterned after the spatially distributed chemoreceptors of some animals, and (3) mimicking the fanning behavior of silkworm moths to enhance the reception of chemical signals by drawing molecules from one direction. The achievements so far and current efforts are reviewed to illustrate the steps to be taken toward future development of this technology.

Ka-band MMIC array system for ACTS aeronautical terminal experiment (Aero-X)

NASA Technical Reports Server (NTRS)

Raquet, Charles A.; Zakrajsek, Robert J.; Lee, Richard Q.; Andro, Monty; Turtle, John P.

1995-01-01

During the summer of 1994, the Advanced Communication Technology Satellite (ACTS) Aeronautical Terminal Experiment (Aero-X) was successfully completed by the NASA Lewis Research Center (LeRC) and the Jet Propulsion Laboratory (JPL). 4.8 and 9.6 Kbps duplex voice links were established between the LeRC Learjet and the ACTS Link Evaluation Terminal (LET) in Cleveland, Ohio, via the ACTS. The antenna system used in this demonstration was developed by LeRC and featured LeRC and US Air Force experimental arrays using GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The antenna system consisted of three arrays mounted inside the LeRC Learjet, pointing out through the windows. An open loop tracking controller developed by LeRC used information from the aircraft position and attitude sensors to automatically steer the arrays toward ACTS during flight JPL ACTS Mobile Terminal (AMT) system hardware was used as transceivers both on the aircraft and at the LET. The single 32 element MMIC transmit array developed by NASA/LeRC and Texas Instruments has an EIRP of 23.4 dBW at boresight. The two 20 GHz MMIC receive arrays were developed in a cooperative effort with the USAF Rome Laboratory/Electronic System Center, taking advantage of existing USAF array development contracts with Boeing and Martin Marietta. The Boeing array has 23 elements and a G/T of 16/6 db/degK at boresight. The Martin Marietta array has 16 elements and a G/T of 16.1 db/degK at boresight. The three proof-of-concept arrays, the array control system and their integration and operation in the Learjet for Aero-X are described.

Design and Flood Control Assessment of 5MWp Fishing and Photovoltaic Power Project in Xinghua City

NASA Astrophysics Data System (ADS)

Guo, Liuchao; Hu, Xiaodong; Su, Yuyan; Wu, Peipei; Weng, Songgan

2017-12-01

In order to reduce coal consumption in Jiangsu Province and develop new energy sources, considering on the distribution of geology, solar energy resources, traffic and grid connection in Xinghua City, the aim is to determine the configuration of photovoltaic modules and photovoltaic array tracking mode, design photovoltaic array and layout scheme. But the project is a wading project, it is built in Dong Tan Lake polder I115, it needs scientific and reasonable evaluation to the effect of Dong Tan Lake’s flood storage and discharge. The results can provide guidance for similar engineering’s design.

Electronic switching spherical array antenna

NASA Technical Reports Server (NTRS)

Stockton, R.

1978-01-01

This work was conducted to demonstrate the performance levels attainable with an ESSA (Electronic Switching Spherical Array) antenna by designing and testing an engineering model. The antenna was designed to satisfy general spacecraft environmental requirements and built to provide electronically commandable beam pointing capability throughout a hemisphere. Constant gain and beam shape throughout large volumetric coverage regions are the principle characteristics. The model is intended to be a prototype of a standard communications and data handling antenna for user scientific spacecraft with the Tracking and Data Relay Satellite System (TDRSS). Some additional testing was conducted to determine the feasibility of an integrated TDRSS and GPS (Global Positioning System) antenna system.

Fabrication of implantable microelectrode arrays by laser cutting of silicone rubber and platinum foil.

PubMed

Schuettler, M; Stiess, S; King, B V; Suaning, G J

2005-03-01

A new method for fabrication of microelectrode arrays comprised of traditional implant materials is presented. The main construction principle is the use of spun-on medical grade silicone rubber as insulating substrate material and platinum foil as conductor (tracks, pads and electrodes). The silicone rubber and the platinum foil are patterned by laser cutting using an Nd:YAG laser and a microcontroller-driven, stepper-motor operated x-y table. The method does not require expensive clean room facilities and offers an extremely short design-to-prototype time of below 1 day. First prototypes demonstrate a minimal achievable feature size of about 30 microm.

Lightweight biometric detection system for human classification using pyroelectric infrared detectors.

PubMed

Burchett, John; Shankar, Mohan; Hamza, A Ben; Guenther, Bob D; Pitsianis, Nikos; Brady, David J

2006-05-01

We use pyroelectric detectors that are differential in nature to detect motion in humans by their heat emissions. Coded Fresnel lens arrays create boundaries that help to localize humans in space as well as to classify the nature of their motion. We design and implement a low-cost biometric tracking system by using off-the-shelf components. We demonstrate two classification methods by using data gathered from sensor clusters of dual-element pyroelectric detectors with coded Fresnel lens arrays. We propose two algorithms for person identification, a more generalized spectral clustering method and a more rigorous example that uses principal component regression to perform a blind classification.

Vehicle antenna for the mobile satellite experiment

NASA Technical Reports Server (NTRS)

Peng, Sheng Y.; Chung, H. H.; Leggiere, D.; Foy, W.; Schaffner, G.; Nelson, J.; Pagels, W.; Vayner, M.; Faller, H. L.; Messer, L.

1988-01-01

A low profile, low cost, printed circuit, electronically steered, right hand circularly polarized phase array antenna system has been developed for the Mobile Satellite Experiment (MSAT-X) Program. The success of this antenna is based upon the development of a crossed-slot element array and detailed trade-off analyses for both the phased array and pointing system design. The optimized system provides higher gain at low elevation angles (20 degrees above the horizon) and broader frequency coverage (approximately 8 1/2 percent bandwidth) than is possible with a patch array. Detailed analysis showed that optimum performance could be achieved with a 19 element array of a triangular lattice geometry of 3.9 inch element spacing. This configuration has the effect of minimizing grating lobes at large scan angles plus it improves the intersatellite isolation. The array has an aperture 20 inches in diameter and is 0.75 inch thick overall, exclusive of the RF and power connector. The pointing system employs a hybrid approach that operates with both an external rate sensor and an internal error signal as a means of fine tuning the beam acquisition and track. Steering the beam is done electronically via 18, 3-bit diode phase shifters. A nineteenth phase shifter is not required as the center element serves as a reference only. Measured patterns and gain show that the array meets the stipulated performance specifications everywhere except at some low elevation angles.

Experiment on a three-beam adaptive array for EHF frequency-hopped signals using a fast algorithm, phase-D

NASA Astrophysics Data System (ADS)

Yen, J. L.; Kremer, P.; Amin, N.; Fung, J.

1989-05-01

The Department of National Defence (Canada) has been conducting studies into multi-beam adaptive arrays for extremely high frequency (EHF) frequency hopped signals. A three-beam 43 GHz adaptive antenna and a beam control processor is under development. An interactive software package for the operation of the array, capable of applying different control algorithms is being written. A maximum signal to jammer plus noise ratio (SJNR) was found to provide superior performance in preventing degradation of user signals in the presence of nearby jammers. A new fast algorithm using a modified conjugate gradient approach was found to be a very efficient way to implement anti-jamming arrays based on maximum SJNR criterion. The present study was intended to refine and simplify this algorithm and to implement the algorithm on an experimental array for real-time evaluation of anti-jamming performance. A three-beam adaptive array was used. A simulation package was used in the evaluation of multi-beam systems using more than three beams and different user-jammer scenarios. An attempt to further reduce the computation burden through continued analysis of maximum SJNR met with limited success. A method to acquire and track an incoming laser beam is proposed.

Experiment on a three-beam adaptive array for EHF frequency-hopped signals using a fast algorithm, phase E

NASA Astrophysics Data System (ADS)

Yen, J. L.; Kremer, P.; Fung, J.

1990-05-01

The Department of National Defence (Canada) has been conducting studies into multi-beam adaptive arrays for extremely high frequency (EHF) frequency hopped signals. A three-beam 43 GHz adaptive antenna and a beam control processor is under development. An interactive software package for the operation of the array, capable of applying different control algorithms is being written. A maximum signal to jammer plus noise ratio (SJNR) has been found to provide superior performance in preventing degradation of user signals in the presence of nearby jammers. A new fast algorithm using a modified conjugate gradient approach has been found to be a very efficient way to implement anti-jamming arrays based on maximum SJNR criterion. The present study was intended to refine and simplify this algorithm and to implement the algorithm on an experimental array for real-time evaluation of anti-jamming performance. A three-beam adaptive array was used. A simulation package was used in the evaluation of multi-beam systems using more than three beams and different user-jammer scenarios. An attempt to further reduce the computation burden through further analysis of maximum SJNR met with limited success. The investigation of a new angle detector for spatial tracking in heterodyne laser space communications was completed.

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

NASA Technical Reports Server (NTRS)

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.

Solar observations with the prototype of the Brazilian Decimetric Array

NASA Astrophysics Data System (ADS)

Sawant, H. S.; Ramesh, R.; Faria, C.; Cecatto, J. R.; Fernandes, F. C. R.; Madsen, F. H. R.; Subramanian, K. R.; Sundararajan, M. S.

The prototype of the Brazilian Decimetric Array BDA consists of 5 element alt-az mounted parabolic mesh type dishes of 4-meter diameter having base lines up to 220 meters in the E--W direction The array was put into regular operation at Cachoeira Paulista Brazil longitude 45 r 00 20 W and latitude 22 r 41 19 S This array operates in the frequency range of 1 2 -- 1 7 GHz Solar observations are carried at sim 1 4 GHz in transit and tracking modes Spatial fine structures superimposed on the one dimensional brightness map of the sun associated with active regions and or with solar activity and their time evolution will be presented In the second phase of the project the frequency range will be increased to 1 2 - 1 7 2 8 and 5 6 GHz Central part of the array will consist of 26 antennas with 4-meter diameter laid out randomically in the square of 256 by 256 meter with minimum and maximum base lines of 8 and 256 meters respectively Details of this array with imaging capabilities in snap shot mode for solar observations and procedure of the phase and amplitude calibrations will be presented The development of instrument will be completed by the beginning of 2008

High resolution telescope

DOEpatents

Massie, Norbert A.; Oster, Yale

1992-01-01

A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activites. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.

Streamlined calibrations of the ATLAS precision muon chambers for initial LHC running

NASA Astrophysics Data System (ADS)

Amram, N.; Ball, R.; Benhammou, Y.; Ben Moshe, M.; Dai, T.; Diehl, E. B.; Dubbert, J.; Etzion, E.; Ferretti, C.; Gregory, J.; Haider, S.; Hindes, J.; Levin, D. S.; Manilow, E.; Thun, R.; Wilson, A.; Weaverdyck, C.; Wu, Y.; Yang, H.; Zhou, B.; Zimmermann, S.

2012-04-01

The ATLAS Muon Spectrometer is designed to measure the momentum of muons with a resolution of dp/p=3% at 100 GeV and 10% at 1 TeV. For this task, the spectrometer employs 355,000 Monitored Drift Tubes (MDTs) arrayed in 1200 chambers. Calibration (RT) functions convert drift time measurements into tube-centered impact parameters for track segment reconstruction. RT functions depend on MDT environmental parameters and so must be appropriately calibrated for local chamber conditions. We report on the creation and application of a gas monitor system based calibration program for muon track reconstruction in the LHC startup phase.

Horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications.

PubMed

Ma, Hongcai; Wu, Lin

2015-07-10

We present the design of a horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications. This solar concentrator consists of an array of telecentric primary concentrators, a horizontally staggered lightguide layer, and a vertically tapered lightguide layer. The primary concentrator is realized by two plano-aspheric lenses with lateral movement and maintains a high F-number over an angle range of ±23.5°. The results of the simulations show that the solar concentrator achieves a high concentration ratio of 500× with ±0.5° of acceptance angle by a single-axis tracker and dual lateral translation stages.

The robot's eyes - Stereo vision system for automated scene analysis

NASA Technical Reports Server (NTRS)

Williams, D. S.

1977-01-01

Attention is given to the robot stereo vision system which maintains the image produced by solid-state detector television cameras in a dynamic random access memory called RAPID. The imaging hardware consists of sensors (two solid-state image arrays using a charge injection technique), a video-rate analog-to-digital converter, the RAPID memory, and various types of computer-controlled displays, and preprocessing equipment (for reflexive actions, processing aids, and object detection). The software is aimed at locating objects and transversibility. An object-tracking algorithm is discussed and it is noted that tracking speed is in the 50-75 pixels/s range.

Reconfigurable Antennas for High Data Rate Multi-beam Communication Systems

NASA Technical Reports Server (NTRS)

Bernhard, Jennifer T.; Michielssen, Eric

2005-01-01

High-speed (2-100 Mb/sec) wireless data communication - whether land- or satellite-based - faces a major challenge: high error rates caused by interference and unpredictable environments. A planar antenna system that can be reconfigured to respond to changing conditions has the potential to dramatically improve data throughput and system reliability. Moreover, new planar antenna designs that reduce array size, weight, and cost can have a significant impact on terrestrial and satellite communication system performance. This research developed new individually-reconfigurable planar antenna array elements that can be adjusted to provide multiple beams while providing increased scan angles and higher aperture efficiency than traditional diffraction-limited arrays. These new elements are microstrip spiral antennas with specialized tuning mechanisms that provide adjustable radiation patterns. We anticipate that these new elements can be used in both large and small arrays for inter-satellite communication as well as tracking of multiple mobile surface-based units. Our work has developed both theoretical descriptions as well as experimental prototypes of the antennas in both single element and array embodiments. The technical summary of the results of this work is divided into six sections: A. Cavity model for analysis and design of pattern reconfigurable antennas; B. Performance of antenna in array configurations for broadside and endfire operation; C. Performance of antenna in array configurations for beam scanning operation; D. Simulation of antennas in infinite phased arrays; E. Demonstration of antenna with commercially-available RF MEMS switches; F. Design of antenna MEMS switch combinations for direct simultaneous fabrication.

Development and testing of bio-inspired microelectromechanical pressure sensor arrays for increased situational awareness for marine vehicles

NASA Astrophysics Data System (ADS)

Dusek, J.; Kottapalli, A. G. P.; Woo, M. E.; Asadnia, M.; Miao, J.; Lang, J. H.; Triantafyllou, M. S.

2013-01-01

The lateral line found on most species of fish is a sensory organ without analog in humans. Using sensory feedback from the lateral line, fish are able to track prey, school, avoid obstacles, and detect vortical flow structures. Composed of both a superficial component, and a component contained within canals beneath the fish’s skin, the lateral line acts in a similar fashion to an array of differential pressure sensors. In an effort to enhance the situational and environmental awareness of marine vehicles, lateral-line-inspired pressure sensor arrays were developed to mimic the enhanced sensory capabilities observed in fish. Three flexible and waterproof pressure sensor arrays were fabricated for use as a surface-mounted ‘smart skin’ on marine vehicles. Two of the sensor arrays were based around the use of commercially available piezoresistive sensor dies, with innovative packaging schemes to allow for flexibility and underwater operation. The sensor arrays employed liquid crystal polymer and flexible printed circuit board substrates with metallic circuits and silicone encapsulation. The third sensor array employed a novel nanocomposite material set that allowed for the fabrication of a completely flexible sensor array. All three sensors were surface mounted on the curved hull of an autonomous kayak vehicle, and tested in both pool and reservoir environments. Results demonstrated that all three sensors were operational while deployed on the autonomous vehicle, and provided an accurate means for monitoring the vehicle dynamics.

Target tracking and pointing for arrays of phase-locked lasers

NASA Astrophysics Data System (ADS)

Macasaet, Van P.; Hughes, Gary B.; Lubin, Philip; Madajian, Jonathan; Zhang, Qicheng; Griswold, Janelle; Kulkarni, Neeraj; Cohen, Alexander; Brashears, Travis

2016-09-01

Arrays of phase-locked lasers are envisioned for planetary defense and exploration systems. High-energy beams focused on a threatening asteroid evaporate surface material, creating a reactionary thrust that alters the asteroid's orbit. The same system could be used to probe an asteroid's composition, to search for unknown asteroids, and to propel interplanetary and interstellar spacecraft. Phased-array designs are capable of producing high beam intensity, and allow beam steering and beam profile manipulation. Modular designs allow ongoing addition of emitter elements to a growing array. This paper discusses pointing control for extensible laser arrays. Rough pointing is determined by spacecraft attitude control. Lateral movement of the laser emitter tips behind the optical elements provides intermediate pointing adjustment for individual array elements and beam steering. Precision beam steering and beam formation is accomplished by coordinated phase modulation across the array. Added cells are incorporated into the phase control scheme by precise alignment to local mechanical datums using fast, optical relative position sensors. Infrared target sensors are also positioned within the datum scheme, and provide information about the target vector relative to datum coordinates at each emitter. Multiple target sensors allow refined determination of the target normal plane, providing information to the phase controller for each emitter. As emitters and sensors are added, local position data allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. Mechanical design and associated phase control that is scalable for target distance and number of emitters is presented.

Development of a Solar Array Drive Assembly for CubeSat

NASA Technical Reports Server (NTRS)

Passaretti, Mike; Hayes, Ron

2010-01-01

Small satellites and in particular CubeSats, have increasingly become more viable as platforms for payloads typically requiring much larger bus structures. As advances in technology make payloads and instruments for space missions smaller, lighter and more power efficient, a niche market is emerging from the university community to perform rapidly developed, low-cost missions on very small spacecraft - micro, nano, and picosatellites. In just the last few years, imaging, biological and new technology demonstration missions have been either proposed or have flown using variations of the CubeSat structure as a basis. As these missions have become more complex, and the CubeSat standard has increased in both size (number of cubes) and mass, available power has become an issue. Body-mounted solar cells provide a minimal amount of power; deployable arrays improve on that baseline but are still limited. To truly achieve maximum power, deployed tracked arrays are necessary. To this end, Honeybee Robotics Spacecraft Mechanisms Corporation, along with MMA of Nederland Colorado, has developed a solar array drive assembly (SADA) and deployable solar arrays specifically for CubeSat missions. In this paper, we discuss the development of the SADA.

Local characterization of hindered Brownian motion by using digital video microscopy and 3D particle tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dettmer, Simon L.; Keyser, Ulrich F.; Pagliara, Stefano

In this article we present methods for measuring hindered Brownian motion in the confinement of complex 3D geometries using digital video microscopy. Here we discuss essential features of automated 3D particle tracking as well as diffusion data analysis. By introducing local mean squared displacement-vs-time curves, we are able to simultaneously measure the spatial dependence of diffusion coefficients, tracking accuracies and drift velocities. Such local measurements allow a more detailed and appropriate description of strongly heterogeneous systems as opposed to global measurements. Finite size effects of the tracking region on measuring mean squared displacements are also discussed. The use of thesemore » methods was crucial for the measurement of the diffusive behavior of spherical polystyrene particles (505 nm diameter) in a microfluidic chip. The particles explored an array of parallel channels with different cross sections as well as the bulk reservoirs. For this experiment we present the measurement of local tracking accuracies in all three axial directions as well as the diffusivity parallel to the channel axis while we observed no significant flow but purely Brownian motion. Finally, the presented algorithm is suitable also for tracking of fluorescently labeled particles and particles driven by an external force, e.g., electrokinetic or dielectrophoretic forces.« less

Fixed Nadir Focus Concentrated Solar Power Applying Reflective Array Tracking Method

NASA Astrophysics Data System (ADS)

Setiawan, B.; DAMayanti, A. M.; Murdani, A.; Habibi, I. I. A.; Wakidah, R. N.

2018-04-01

The Sun is one of the most potential renewable energy develoPMent to be utilized, one of its utilization is for solar thermal concentrators, CSP (Concentrated Solar Power). In CSP energy conversion, the concentrator is as moving the object by tracking the sunlight to reach the focus point. This method need quite energy consumption, because the unit of the concentrators has considerable weight, and use large CSP, means the existence of the usage unit will appear to be wider and heavier. The addition of weight and width of the unit will increase the torque to drive the concentrator and hold the wind gusts. One method to reduce energy consumption is direct the sunlight by the reflective array to nadir through CSP with Reflective Fresnel Lens concentrator. The focus will be below the nadir direction, and the position of concentrator will be fixed position even the angle of the sun’s elevation changes from morning to afternoon. So, the energy concentrated maximally, because it has been protected from wind gusts. And then, the possibility of dAMage and changes in focus construction will not occur. The research study and simulation of the reflective array (mechanical method) will show the reflective angle movement. The distance between reflectors and their angle are controlled by mechatronics. From the simulation using fresnel 1m2, and efficiency of solar energy is 60.88%. In restriction, the intensity of sunlight at the tropical circles 1KW/peak, from 6 AM until 6 PM.

The Track of Policies for Educational Equality and Its Implications in Korea

ERIC Educational Resources Information Center

Jo, Seog Hun

2013-01-01

Most countries have taken equality of education as a paramount issue, but policy initiatives have not taken the same patterns across the nations. This paper addressed the features of equality policies and their changes in South Korea through an array of target groups and types of policy measures. According to a contingency approach, Korea relied…

Autonomous omnidirectional spacecraft antenna system

NASA Technical Reports Server (NTRS)

Taylor, T. H.

1983-01-01

The development of a low gain Electronically Switchable Spherical Array Antenna is discussed. This antenna provides roughly 7 dBic gain for receive/transmit operation between user satellites and the Tracking and Data Relay Satellite System. When used as a pair, the antenna provides spherical coverage. The antenna was tested in its primary operating modes: directed beam, retrodirective, and Omnidirectional.

Compendium of Instrumentation Whitepapers on Frontier Physics Needs for Snowmass 2013

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipton, R.

2013-01-01

Contents of collection of whitepapers include: Operation of Collider Experiments at High Luminosity; Level 1 Track Triggers at HL-LHC; Tracking and Vertex Detectors for a Muon Collider; Triggers for hadron colliders at the energy frontier; ATLAS Upgrade Instrumentation; Instrumentation for the Energy Frontier; Particle Flow Calorimetry for CMS; Noble Liquid Calorimeters; Hadronic dual-readout calorimetry for high energy colliders; Another Detector for the International Linear Collider; e+e- Linear Colliders Detector Requirements and Limitations; Electromagnetic Calorimetry in Project X Experiments The Project X Physics Study; Intensity Frontier Instrumentation; Project X Physics Study Calorimetry Report; Project X Physics Study Tracking Report; The LHCbmore » Upgrade; Neutrino Detectors Working Group Summary; Advanced Water Cherenkov R&D for WATCHMAN; Liquid Argon Time Projection Chamber (LArTPC); Liquid Scintillator Instrumentation for Physics Frontiers; A readout architecture for 100,000 pixel Microwave Kinetic In- ductance Detector array; Instrumentation for New Measurements of the Cosmic Microwave Background polarization; Future Atmospheric and Water Cherenkov ?-ray Detectors; Dark Energy; Can Columnar Recombination Provide Directional Sensitivity in WIMP Search?; Instrumentation Needs for Detection of Ultra-high Energy Neu- trinos; Low Background Materials for Direct Detection of Dark Matter; Physics Motivation for WIMP Dark Matter Directional Detection; Solid Xenon R&D at Fermilab; Ultra High Energy Neutrinos; Instrumentation Frontier: Direct Detection of WIMPs; nEXO detector R&D; Large Arrays of Air Cherenkov Detectors; and Applications of Laser Interferometry in Fundamental Physics Experiments.« less

Feasibility Activities Completed for the Direct Data Distribution (D(sup )3) Experiment

NASA Technical Reports Server (NTRS)

Wald, Lawrence W.

2000-01-01

The Direct Data Distribution (D(sup 3)) project being designed at the NASA Glenn Research Center at Lewis Field will demonstrate a high-performance communications system that transmits information at up to 1.2 gigabits per second (Gbps) from an advanced technology payload carried by the space shuttles in low Earth orbit to small (0.9-m) autonomously tracking terminals on the Earth. The flight communications package features a solid-state, phased-array antenna operating in the commercial K-band frequency that electronically steers two independently controlled downlink beams toward low-cost tracking ground terminals. The array enables agile, vibration-free beam steering at reduced size and weight with increased reliability over traditional mechanically steered reflectors. The flight experiment will also demonstrate efficient digital modulation technology that allows transmission of substantially increased amounts of latency-tolerant data (up to 72 Gb of data per minute of contact time) with very high quality (10(exp -11) bit error rate). D(sup 3) enables transmission from low-Earth-orbit science spacecraft, the shuttles, or the International Space Station directly to NASA field centers and principle investigator sites, or directly into the commercial terrestrial telecommunications network for remote distribution and archive. The ground terminal features a cryocooled receiver for ultralow noise and a reduced antenna aperture as well as open-loop tracking for unattended operations. The D(sup 3) technology validation and service demonstration will help to facilitate NASA's transition from using Government-owned communications assets to using commercially provided services.

Signal and array processing techniques for RFID readers

NASA Astrophysics Data System (ADS)

Wang, Jing; Amin, Moeness; Zhang, Yimin

2006-05-01

Radio Frequency Identification (RFID) has recently attracted much attention in both the technical and business communities. It has found wide applications in, for example, toll collection, supply-chain management, access control, localization tracking, real-time monitoring, and object identification. Situations may arise where the movement directions of the tagged RFID items through a portal is of interest and must be determined. Doppler estimation may prove complicated or impractical to perform by RFID readers. Several alternative approaches, including the use of an array of sensors with arbitrary geometry, can be applied. In this paper, we consider direction-of-arrival (DOA) estimation techniques for application to near-field narrowband RFID problems. Particularly, we examine the use of a pair of RFID antennas to track moving RFID tagged items through a portal. With two antennas, the near-field DOA estimation problem can be simplified to a far-field problem, yielding a simple way for identifying the direction of the tag movement, where only one parameter, the angle, needs to be considered. In this case, tracking of the moving direction of the tag simply amounts to computing the spatial cross-correlation between the data samples received at the two antennas. It is pointed out that the radiation patterns of the reader and tag antennas, particularly their phase characteristics, have a significant effect on the performance of DOA estimation. Indoor experiments are conducted in the Radar Imaging and RFID Labs at Villanova University for validating the proposed technique for target movement direction estimations.

Protein recognition by a pattern-generating fluorescent molecular probe.

PubMed

Pode, Zohar; Peri-Naor, Ronny; Georgeson, Joseph M; Ilani, Tal; Kiss, Vladimir; Unger, Tamar; Markus, Barak; Barr, Haim M; Motiei, Leila; Margulies, David

2017-12-01

Fluorescent molecular probes have become valuable tools in protein research; however, the current methods for using these probes are less suitable for analysing specific populations of proteins in their native environment. In this study, we address this gap by developing a unimolecular fluorescent probe that combines the properties of small-molecule-based probes and cross-reactive sensor arrays (the so-called chemical 'noses/tongues'). On the one hand, the probe can detect different proteins by generating unique identification (ID) patterns, akin to cross-reactive arrays. On the other hand, its unimolecular scaffold and selective binding enable this ID-generating probe to identify combinations of specific protein families within complex mixtures and to discriminate among isoforms in living cells, where macroscopic arrays cannot access. The ability to recycle the molecular device and use it to track several binding interactions simultaneously further demonstrates how this approach could expand the fluorescent toolbox currently used to detect and image proteins.

DEATH-STAR: Silicon and photovoltaic fission fragment detector arrays for light-ion induced fission correlation studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koglin, J. D.; Burke, J. T.; Fisher, S. E.

Here, the Direct Excitation Angular Tracking pHotovoltaic-Silicon Telescope ARray (DEATH-STAR) combines a series of 12 silicon detectors in a ΔE–E configuration for charged particle identification with a large-area array of 56 photovoltaic (solar) cells for detection of fission fragments. The combination of many scattering angles and fission fragment detectors allows for an angular-resolved tool to study reaction cross sections using the surrogate method, anisotropic fission distributions, and angular momentum transfers through stripping, transfer, inelastic scattering, and other direct nuclear reactions. The unique photovoltaic detectors efficiently detect fission fragments while being insensitive to light ions and have a timing resolution ofmore » 15.63±0.37 ns. Alpha particles are detected with a resolution of 35.5 keV 1σ at 7.9 MeV. Measured fission fragment angular distributions are also presented.« less

Digital solar edge tracker for the Halogen Occultation Experiment

NASA Technical Reports Server (NTRS)

Mauldin, L. E., III; Moore, A. S.; Stump, C. W.; Mayo, L. S.

1987-01-01

The optical and electronic design of the Halogen Occultation Experiment (Haloe) elevation sun sensor is described. The Haloe instrument is a gas-correlation radiometer now being developed at NASA Langley for the Upper Atmosphere Research Satellite. The system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned monolithic CCD. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the Haloe science instantaneous field of view (IFOV) across the vertical solar diameter during instrument calibration and then to maintain the science IFOV 4 arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 700-nm operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability.

DEATH-STAR: Silicon and Photovoltaic Fission Fragment Detector Arrays for Light-Ion Induced Fission Correlation Studies

NASA Astrophysics Data System (ADS)

Koglin, J. D.; Burke, J. T.; Fisher, S. E.; Jovanovic, I.

2017-05-01

The Direct Excitation Angular Tracking pHotovoltaic-Silicon Telescope ARray (DEATH-STAR) combines a series of 12 silicon detectors in a ΔE - E configuration for charged particle identification with a large-area array of 56 photovoltaic (solar) cells for detection of fission fragments. The combination of many scattering angles and fission fragment detectors allows for an angular-resolved tool to study reaction cross sections using the surrogate method, anisotropic fission distributions, and angular momentum transfers through stripping, transfer, inelastic scattering, and other direct nuclear reactions. The unique photovoltaic detectors efficiently detect fission fragments while being insensitive to light ions and have a timing resolution of 15.63±0.37 ns. Alpha particles are detected with a resolution of 35.5 keV 1σ at 7.9 MeV. Measured fission fragment angular distributions are also presented.

DEATH-STAR: Silicon and photovoltaic fission fragment detector arrays for light-ion induced fission correlation studies

DOE PAGES

Koglin, J. D.; Burke, J. T.; Fisher, S. E.; ...

2017-02-20

Here, the Direct Excitation Angular Tracking pHotovoltaic-Silicon Telescope ARray (DEATH-STAR) combines a series of 12 silicon detectors in a ΔE–E configuration for charged particle identification with a large-area array of 56 photovoltaic (solar) cells for detection of fission fragments. The combination of many scattering angles and fission fragment detectors allows for an angular-resolved tool to study reaction cross sections using the surrogate method, anisotropic fission distributions, and angular momentum transfers through stripping, transfer, inelastic scattering, and other direct nuclear reactions. The unique photovoltaic detectors efficiently detect fission fragments while being insensitive to light ions and have a timing resolution ofmore » 15.63±0.37 ns. Alpha particles are detected with a resolution of 35.5 keV 1σ at 7.9 MeV. Measured fission fragment angular distributions are also presented.« less

Protein recognition by a pattern-generating fluorescent molecular probe

NASA Astrophysics Data System (ADS)

Pode, Zohar; Peri-Naor, Ronny; Georgeson, Joseph M.; Ilani, Tal; Kiss, Vladimir; Unger, Tamar; Markus, Barak; Barr, Haim M.; Motiei, Leila; Margulies, David

2017-12-01

Fluorescent molecular probes have become valuable tools in protein research; however, the current methods for using these probes are less suitable for analysing specific populations of proteins in their native environment. In this study, we address this gap by developing a unimolecular fluorescent probe that combines the properties of small-molecule-based probes and cross-reactive sensor arrays (the so-called chemical 'noses/tongues'). On the one hand, the probe can detect different proteins by generating unique identification (ID) patterns, akin to cross-reactive arrays. On the other hand, its unimolecular scaffold and selective binding enable this ID-generating probe to identify combinations of specific protein families within complex mixtures and to discriminate among isoforms in living cells, where macroscopic arrays cannot access. The ability to recycle the molecular device and use it to track several binding interactions simultaneously further demonstrates how this approach could expand the fluorescent toolbox currently used to detect and image proteins.

Science requirements for Heavy Nuclei Collection (HNC) experiment on NASA Long Duration Exposure Facility (LDEF) Mission 2

NASA Technical Reports Server (NTRS)

Price, P. Buford

1991-01-01

The Heavy Nuclei Collection (HNC) is a passive array of stacks of a special glass, 14 sheets thick, that record tracks of ultraheavy cosmic rays for later readout by automated systems on Earth. The primary goal is to determine the relative abundances of both the odd- and even-Z cosmic rays with Z equal to or greater than 50 with statistics a factor at least 60 greater than obtained in HEAO-3 and to obtain charge resolution at least as good as 0.25 charge unit. The secondary goal is to search for hypothetical particles such as superheavy elements. The HNC detector array will have a cumulative collection power equivalent to flying 32 sq m of detectors in space for 4 years. The array will be flown as a free-flight spacecraft and/or attached to Space Station Freedom.

Solar tracker motor having a fixed caliper and a translating caliper each with an electromagnetic brake system

DOEpatents

Rau, Scott James

2013-01-29

Concepts and technologies described herein provide for an accurate and cost-effective method for rotating a solar array disk for tracking the movement of the sun. According to various aspects, a motor includes a fixed caliper and a translating caliper positioned adjacent to one another. Electromagnetically controlled brakes on the translating caliper grip the solar array disk while adjacent, but spaced apart, electromagnets on the fixed caliper and the translating caliper are energized to create an attractive force that pulls the translating caliper with the solar array disk toward the fixed caliper. After reaching the fixed caliper, brakes on the fixed caliper are engaged with the disk, brakes on the translating caliper are released from the disk, and the translating caliper is pushed back to the starting location where the process repeats until the desired rotation is completed.

Monolithic microwave integrated circuits for sensors, radar, and communications systems; Proceedings of the Meeting, Orlando, FL, Apr. 2-4, 1991

NASA Technical Reports Server (NTRS)

Leonard, Regis F. (Editor); Bhasin, Kul B. (Editor)

1991-01-01

Consideration is given to MMICs for airborne phased arrays, monolithic GaAs integrated circuit millimeter wave imaging sensors, accurate design of multiport low-noise MMICs up to 20 GHz, an ultralinear low-noise amplifier technology for space communications, variable-gain MMIC module for space applications, a high-efficiency dual-band power amplifier for radar applications, a high-density circuit approach for low-cost MMIC circuits, coplanar SIMMWIC circuits, recent advances in monolithic phased arrays, and system-level integrated circuit development for phased-array antenna applications. Consideration is also given to performance enhancement in future communications satellites with MMIC technology insertion, application of Ka-band MMIC technology for an Orbiter/ACTS communications experiment, a space-based millimeter wave debris tracking radar, low-noise high-yield octave-band feedback amplifiers to 20 GHz, quasi-optical MESFET VCOs, and a high-dynamic-range mixer using novel balun structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharyya, R.; Dey, S.; Ghosh, Sanjay K.

Various phenomenological models presented over the years have hinted at the possible presence of strangelets, which are nuggets of Strange Quark Matter (SQM), in cosmic rays. One way to search for such rare events is through the deployment of large area Nuclear Track Detector (NTD) arrays at high mountain altitudes. Before the deployment of any such array can begin, a detailed study of the radiation background is essential. Also, a proper understanding of the response of detectors exposed to extreme weather conditions is necessary. With that aim, pilot studies were carried out at various high altitude locations in India suchmore » as Darjeeling (2200 m a.m.s.l), Ooty (2200 m a.m.s.l) and Hanle (4500 m a.m.s.l). Small arrays of CR-39 as well as high threshold Polyethylene Terephthalate (PET) detectors were given open air exposures for periods ranging from three months to two years. The findings of such studies are reported in this paper.« less

A Magnetic Tracking System based on Highly Sensitive Integrated Hall Sensors

NASA Astrophysics Data System (ADS)

Schlageter, Vincent; Drljaca, Predrag; Popovic, Radivoje S.; KuČERA, Pavel

A tracking system with five degrees of freedom based on a 2D-array of 16 Hall sensors and a permanent magnet is presented in this paper. The sensitivity of the Hall sensors is increased by integrated micro- and external macro-flux-concentrators. Detection distance larger than 20cm (during one hour without calibration) is achieved using a magnet of 0.2cm3. This corresponds to a resolution of the sensors of 0.05µTrms. The position and orientation of the marker is displayed in real time at least 20 times per second. The sensing system is small enough to be hand-held and can be used in a normal environment. This presented tracking system has been successfully applied to follow a small swallowed magnet through the entire human digestive tube. This approach is extremely promising as a new non-invasive diagnostic technique in gastro-enterology.

Status of the evidence for a magnetic monopole

NASA Technical Reports Server (NTRS)

Price, P. B.

1975-01-01

The experimental evidence supporting the detection of a moving magnetic monopole, using a balloon-borne array of track detectors, was presented. Although the results cannot be proved to have been produced by a monopole, they do not seem to have been produced by any nucleus. The very high, roughly constant ionization rate inferred from track etch rate measurements in a stack of Lexan detectors implies passage of a minimum-ionizing particle more highly charged than any known nucleus, yet the Cerenkov film detectors indicated a velocity less than about 0.68 times the speed of light and the size of the track in the nuclear emulsion indicated a velocity approximately equal to 0.5 times the speed of light. At this velocity the ionization rate of a highly electrically charged particle would have changed dramatically with pathlength unless its mass to charge ratio were far greater than that of a nucleus.

Free-space laser communication technologies IV; Proceedings of the 4th Conference, Los Angeles, CA, Jan. 23, 24, 1992

NASA Technical Reports Server (NTRS)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1992-01-01

Papers included in this volume are grouped under topics of receivers; laser transmitters; components; system analysis, performance, and applications; and beam control (pointing, acquisition, and tracking). Papers are presented on an experimental determination of power penalty contributions in an optical Costas-type phase-locked loop receiver, a resonant laser receiver for free-space laser communications, a simple low-loss technique for frequency-locking lasers, direct phase modulation of laser diodes, and a silex beacon. Particular attention is given to experimental results on an optical array antenna for nonmechanical beam steering, a potassium Faraday anomalous dispersion optical filter, a 100-Mbps resonant cavity phase modulator for coherent optical communications, a numerical simulation of a 325-Mbit/s QPPM optical communication system, design options for an optical multiple-access data relay terminal, CCD-based optical tracking loop design trades, and an analysis of a spatial-tracking subsystem for optical communications.

Optical lattice-like cladding waveguides by direct laser writing: fabrication, luminescence, and lasing.

PubMed

Nie, Weijie; He, Ruiyun; Cheng, Chen; Rocha, Uéslen; Rodríguez Vázquez de Aldana, Javier; Jaque, Daniel; Chen, Feng

2016-05-15

We report on the fabrication of optical lattice-like waveguide structures in an Nd:YAP laser crystal by using direct femtosecond laser writing. With periodically arrayed laser-induced tracks, the waveguiding cores can be located in either the regions between the neighbored tracks or the central zone surrounded by a number of tracks as outer cladding. The polarization of the femtosecond laser pulses for the inscription has been found to play a critical role in the anisotropic guiding behaviors of the structures. The confocal photoluminescence investigations reveal different stress-induced modifications of the structures inscribed by different polarization of the femtosecond laser beam, which are considered to be responsible for the refractive index changes of the structures. Under optical pump at 808 nm, efficient waveguide lasing at ∼1  μm wavelength has been realized from the optical lattice-like structure, which exhibits potential applications as novel miniature light sources.

Adaptive DIT-Based Fringe Tracking and Prediction at IOTA

NASA Technical Reports Server (NTRS)

Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

2004-01-01

An automatic fringe tracking system has been developed and implemented at the Infrared Optical Telescope Array (IOTA). In testing during May 2002, the system successfully minimized the optical path differences (OPDs) for all three baselines at IOTA. Based on sliding window discrete Fourier transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on off-line data. Implemented in ANSI C on the 266 MHZ PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. Preliminary analysis on an extension of this algorithm indicates a potential for predictive tracking, although at present, real-time implementation of this extension would require significantly more computational capacity.

Experimental implementation of fiber optic bundle array wide FOV free space optical communications receiver.

PubMed

Brown, Andrea M; Hahn, Daniel V; Brown, David M; Rolander, Nathan W; Bair, Chun-Huei; Sluz, Joseph E

2012-06-20

A gimbal-free wide field-of-regard (FOR) optical receiver has been built in a laboratory setting for proof-of-concept testing. Multiple datasets are presented that examine the overall FOR of the system and the receiver's ability to track and collect a signal from a moving source. The design is not intended to compete with traditional free space optical communication systems, but rather offer an alternative design that minimizes the number and complexity of mechanical components required at the surface of a small mobile platform. The receiver is composed of a micro-lens array and hexagonal bundles of large core optical fibers that route the optical signal to remote detectors and electronics. Each fiber in the bundle collects power from a distinct solid angle of space and a piezo-electric transducer is used to translate the micro-lens array and optimize coupling into a given fiber core in the bundle. The micro-lens to fiber bundle design is scalable, modular, and can be replicated in an array to increase aperture size.

Magnetomicrofluidics Circuits for Organizing Bioparticle Arrays

NASA Astrophysics Data System (ADS)

Abedini-Nassab, Roozbeh

Single-cell analysis (SCA) tools have important applications in the analysis of phenotypic heterogeneity, which is difficult or impossible to analyze in bulk cell culture or patient samples. SCA tools thus have a myriad of applications ranging from better credentialing of drug therapies to the analysis of rare latent cells harboring HIV infection or in Cancer. However, existing SCA systems usually lack the required combination of programmability, flexibility, and scalability necessary to enable the study of cell behaviors and cell-cell interactions at the scales sufficient to analyze extremely rare events. To advance the field, I have developed a novel, programmable, and massively-parallel SCA tool which is based on the principles of computer circuits. By integrating these magnetic circuits with microfluidics channels, I developed a platform that can organize a large number of single particles into an array in a controlled manner. My magnetophoretic circuits use passive elements constructed in patterned magnetic thin films to move cells along programmed tracks with an external rotating magnetic field. Cell motion along these tracks is analogous to the motion of charges in an electrical conductor, following a rule similar to Ohm's law. I have also developed asymmetric conductors, similar to electrical diodes, and storage sites for cells that behave similarly to electrical capacitors. I have also developed magnetophoretic circuits which use an overlaid pattern of microwires to switch single cells between different tracks. This switching mechanism, analogous to the operation of electronic transistors, is achieved by establishing a semiconducting gap in the magnetic pattern which can be changed from an insulating state to a conducting state by application of electrical current to an overlaid electrode. I performed an extensive study on the operation of transistors to optimize their geometry and minimize the required gate currents. By combining these elements into integrated circuits, I have built devices which are capable of organizing a precise number of cells into individually addressable array sites, similar to how a random access memory (RAM) stores electronic data. My programmable magnetic circuits allow for the organization of both cells and single-cell pairs into large arrays. Single cells can also potentially be retrieved for downstream high-throughput genomic analysis. In order to enhance the efficiency of the tool and to increase the delivery speed of the particles, I have also developed microfluidics systems that are combined with the magnetophoretic circuits. This hybrid system, called magnetomicrofluidics, is capable of rapidly organizing an array of particles and cells with the high precision and control. I have also shown that cells can be grown inside these chips for multiple days, enabling the long-term phenotypic analysis of rare cellular events. These types of studies can reveal important insights about the intercellular signaling networks and answer crucial questions in biology and immunology.

Investigation of the infrasound produced by geophysical events such as volcanoes, thunder, and avalanches: the case for local infrasound monitoring (Invited)

NASA Astrophysics Data System (ADS)

Johnson, J. B.; Marcillo, O. E.; Arechiga, R. O.; Johnson, R.; Edens, H. E.; Marshall, H.; Havens, S.; Waite, G. P.

2010-12-01

Volcanoes, lightning, and mass wasting events generate substantial infrasonic energy that propagates for long distances through the atmosphere with generally low intrinsic attenuation. Although such sources are often studied with regional infrasound arrays that provide important records of their occurrence, position, and relative magnitudes these signals recorded at tens to hundreds of kilometers are often significantly affected by propagation effects. Complex atmospheric structure, due to heterogeneous winds and temperatures, and intervening topography can be responsible for multi-pathing, signal attenuation, and focusing or, alternatively, information loss (i.e., a shadow zone). At far offsets, geometric spreading diminishes signal amplitude requiring low noise recording sites and high fidelity microphones. In contrast recorded excess pressures at local distances are much higher in amplitude and waveforms are more representative of source phenomena. We report on recent studies of volcanoes, thunder, and avalanches made with networks and arrays of infrasound sensors deployed local (within a few km) to the source. At Kilauea Volcano (Hawaii) we deployed a network of ~50 infrasound sensitive sensors (flat from 50 s to 50 Hz) to track the coherence of persistent infrasonic tremor signals in the near-field (out to a few tens of kilometers). During periods of high winds (> 5-10 m/s) we found significant atmospheric influence for signals recorded at stations only a few kilometers from the source. Such observations have encouraged us to conduct a range of volcano, thunder, and snow avalanche studies with networks of small infrasound arrays (~30 m aperture) deployed close to the source region. We present results from local microphone deployments (12 sensors) at Santiaguito Volcano (Guatemala) where we are able to precisely (~10 m resolution) locate acoustic sources from explosions and rock falls. We also present results from our thunder mapping acoustic arrays (15 sensors) in the Magdalena Mountains of New Mexico capable of mapping lightning channels more than 10 km in extent whose positions are corroborated by the radio wave detecting lightning mapping array. We also discuss the recent implementation of a network of snow avalanche detection arrays (12 sensors) in Idaho that are used to monitor and track and map infrasound produced by moving sources. We contend that local infrasound deployment is analogous to local seismic monitoring in that it enables precision localization and interpretation of source phenomena.

KSC00pp1629

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, FLA. -- A repair crew begin working on replacing a broken cleat on this track of the crawler-transporter. The crack was noticed as the crawler-transporter was moving Space Shuttle Endeavour to Launch Pad 39B. Rollout was delayed until the cleat could be replaced. The Space Shuttle was hard down on the pad several hours later. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC-00dig065

NASA Image and Video Library

2000-10-31

The cracked cleat on the crawler-transporter track that stalled the rollout of Space Shuttle Endeavour lies on the ground near Launch Pad 39B. The cracked cleat forced the reverse of the rollout back outside the pad gate so the cleat could be repaired on flat ground before moving up the incline to the top of the pad. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC-00pp1635

NASA Image and Video Library

2000-10-31

A new cleat, or shoe, for one of the tracks on the crawler-transporter sits on the ground near the vehicle (in the background). A cracked cleat was noticed on the crawler as it was rolling Space Shuttle Endeavour and the Mobile Launcher Platform out to Launch Pad 39B. The rollout is being suspended while the cleat is replaced. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC-00pp1629

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, FLA. -- A repair crew begin working on replacing a broken cleat on this track of the crawler-transporter. The crack was noticed as the crawler-transporter was moving Space Shuttle Endeavour to Launch Pad 39B. Rollout was delayed until the cleat could be replaced. The Space Shuttle was hard down on the pad several hours later. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC-00pp1634

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, FLA. -- Space Shuttle Endeavour, atop the Mobile Launcher Platform, moves through the gate a second time to Launch Pad 39B. After a cracked cleat was noticed on one of the eight tracks on the crawler-transporter, the vehicle reversed direction to level ground where the cleat is being replaced. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC00pp1634

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, FLA. -- Space Shuttle Endeavour, atop the Mobile Launcher Platform, moves through the gate a second time to Launch Pad 39B. After a cracked cleat was noticed on one of the eight tracks on the crawler-transporter, the vehicle reversed direction to level ground where the cleat is being replaced. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

VLF Radio Wave Propagation Across the Day/Night Terminator

NASA Astrophysics Data System (ADS)

Burch, H.; Moore, R. C.

2016-12-01

In May 2016, a new array of VLF radio receivers was deployed spanning the East Coast of the United States. We present preliminary observations from the array, which was designed in part to track the propagation of the narrowband VLF transmitter signal, NAA (24.0 kHz), down the coast from Cutler, Maine. Amplitude, phase, and polarization observations are compared over multiple days and at different times of year to investigate the dependence of VLF propagation characteristics on solar zenith angle. Measurements are compared to simulations using the Long Wave Propagation Capability code (LWPC) in order to evaluate the accuracy of LWPC's built-in ionosphere model. Efforts to improve the ionosphere model based on observations are discussed.

Solar-Electrochemical Power System for a Mars Mission

NASA Technical Reports Server (NTRS)

Withrow, Colleen A.; Morales, Nelson

1994-01-01

This report documents a sizing study of a variety of solar electrochemical power systems for the intercenter NASA study known as 'Mars Exploration Reference Mission'. Power systems are characterized for a variety of rovers, habitation modules, and space transport vehicles based on requirements derived from the reference mission. The mission features a six-person crew living on Mars for 500 days. Mission power requirements range from 4 kWe to 120 kWe. Primary hydrogen and oxygen fuel cells, regenerative hydrogen and oxygen fuel cells, sodium sulfur batteries advanced photovoltaic solar arrays of gallium arsenide on germanium with tracking and nontracking mechanisms, and tent solar arrays of gallium arsenide on germanium are evaluated and compared.

Photoacoustic imaging velocimetry for flow-field measurement.

PubMed

Ma, Songbo; Yang, Sihua; Xing, Da

2010-05-10

We present the photoacoustic imaging velocimetry (PAIV) method for flow-field measurement based on a linear transducer array. The PAIV method is realized by using a Q-switched pulsed laser, a linear transducer array, a parallel data-acquisition equipment and dynamic focusing reconstruction. Tracers used to track liquid flow field were real-timely detected, two-dimensional (2-D) flow visualization was successfully reached, and flow parameters were acquired by measuring the movement of the tracer. Experimental results revealed that the PAIV method would be developed into 3-D imaging velocimetry for flow-field measurement, and potentially applied to research the security and targeting efficiency of optical nano-material probes. (c) 2010 Optical Society of America.

Direction of Radio Finding via MUSIC (Multiple Signal Classification) Algorithm for Hardware Design System

NASA Astrophysics Data System (ADS)

Zhang, Zheng

2017-10-01

Concept of radio direction finding systems, which use radio direction finding is based on digital signal processing algorithms. Thus, the radio direction finding system becomes capable to locate and track signals by the both. Performance of radio direction finding significantly depends on effectiveness of digital signal processing algorithms. The algorithm uses the Direction of Arrival (DOA) algorithms to estimate the number of incidents plane waves on the antenna array and their angle of incidence. This manuscript investigates implementation of the DOA algorithms (MUSIC) on the uniform linear array in the presence of white noise. The experiment results exhibit that MUSIC algorithm changed well with the radio direction.

Quantification of asymmetric microtubule nucleation at sub-cellular structures

PubMed Central

Zhu, Xiaodong; Kaverina, Irina

2012-01-01

Cell polarization is important for multiple physiological processes. In polarized cells, microtubules (MTs) are organized into a spatially polarized array. Generally, in non-differentiated cells, it is assumed that MTs are symmetrically nucleated exclusively from centrosome (microtubule organizing center, MTOC) and then reorganized into the asymmetric array. We have recently identified the Golgi complex as an additional MTOC that asymmetrically nucleates MTs toward one side of the cell. Methods used for alternative MTOC identification include microtubule re-growth after complete drug-induced depolymerization and tracking of growing microtubules using fluorescence labeled MT +TIP binding proteins in living cells. These approaches can be used for quantification of MT nucleation sites at diverse sub-cellular structures. PMID:21773933

High resolution telescope including an array of elemental telescopes aligned along a common axis and supported on a space frame with a pivot at its geometric center

DOEpatents

Norbert, M.A.; Yale, O.

1992-04-28

A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employes speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by a electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activities. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes. 15 figs.

High resolution telescope including an array of elemental telescopes aligned along a common axis and supported on a space frame with a pivot at its geometric center

DOEpatents

Norbert, Massie A.; Yale, Oster

1992-01-01

A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employes speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by a electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activities. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.

Phased-array radar for airborne systems

NASA Astrophysics Data System (ADS)

Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

2003-09-01

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

A Tracking Sun Photometer Without Moving Parts

NASA Technical Reports Server (NTRS)

Strawa, Anthony W.

2012-01-01

This innovation is small, lightweight, and consumes very little electricity as it measures the solar energy attenuated by gases and aerosol particles in the atmosphere. A Sun photometer is commonly used on the Earth's surface, as well as on aircraft, to determine the solar energy attenuated by aerosol particles in the atmosphere and their distribution of sizes. This information is used to determine the spatial and temporal distribution of gases and aerosols in the atmosphere, as well as their distribution sizes. The design for this Sun photometer uses a combination of unique optics and a charge coupled device (CCD) array to eliminate moving parts and make the instrument more reliable. It could be selfcalibrating throughout the year. Data products would be down-welling flux, the direct-diffuse flux ratio, column abundance of gas phase constituents, aerosol optical depth at multiple-wavelengths, phase functions, cloud statistics, and an estimate of the representative size of atmospheric particles. These measurements can be used to obtain an estimate of aerosol size distribution, refractive index, and particle shape. Incident light is received at a light-reflecting (inner) surface, which is a truncated paraboloid. Light arriving from a hemispheric field of view (solid angle 2 steradians) enters the reflecting optic at an entrance aperture at, or adjacent to, the focus of the paraboloid, and is captured by the optic. Most of this light is reflected from an inner surface. The light proceeds substantially parallel to the paraboloid axis, and is detected by an array detector located near an exit aperture. Each of the entrance and exit apertures is formed by the intersection of the paraboloid with a plane substantially perpendicular to the paraboloid axis. Incident (non-reflected) light from a source of limited extent (the Sun) illuminates a limited area on the detector array. Both direct and diffuse illumination may be reflected, or not reflected, before being received on the detector array. As the Sun traverses a path in the sky over some time interval, the track of the Sun can be traced on the detector array. A suitably modified Sun photometer might be used to study the dynamics of an environment on another planet or satellite with an atmosphere.

Laboratory Scale Prototype of a Low-Speed Electrodynamic Levitation System Based on a Halbach Magnet Array

ERIC Educational Resources Information Center

Iniguez, J.; Raposo, V.

2009-01-01

In this paper we analyse the behaviour of a small-scale model of a magnetic levitation system based on the Inductrack concept. Drag and lift forces acting on our prototype, moving above a continuous copper track, are studied analytically following a simple low-speed approach. The experimental results are in good agreement with the theoretical…

Trigger drift chamber for the upgraded mark II detector at PEP

NASA Astrophysics Data System (ADS)

Ford, W. T.; Smith, J. G.; Wagner, S. R.; Weber, P.; White, S. L.; Alvarez, M.; Calviño, F.; Fernandez, E.

1987-04-01

A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ˜ 90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented.

Context-Aided Tracking with Adaptive Hyperspectral Imagery

DTIC Science & Technology

2011-06-01

narrow spectral bands (e). . . . . . . . . . . . . . . . . . . . . 14 ix Figure Page 2.2. An illustration of a small portion of a digital micromirror ...incorporates two light paths: imaging and spectroscopy. Each pixel is steered towards a light path indepen- dently via the digital micromirror device (DMD...With the advent of digital micromirror device (DMD) arrays (DMA), the Rochester Institute of Technology Multi-Object Spectrometer (RITMOS) [36

That's Not What You Said Earlier: Preschoolers Expect Partners to be Referentially Consistent

ERIC Educational Resources Information Center

Graham, Susan A.; Sedivy, Julie; Khu, Melanie

2014-01-01

In a conversation, adults expect speakers to be consistent in their use of a particular expression. We examine whether four-year-olds expect speakers to use consistent referential descriptions and whether these expectations are partner-specific. Using an eye-tracking paradigm, we presented four-year-olds with arrays of objects on a screen. During…

Fuzzy logic control of stand-alone photovoltaic system with battery storage

NASA Astrophysics Data System (ADS)

Lalouni, S.; Rekioua, D.; Rekioua, T.; Matagne, E.

Photovoltaic energy has nowadays an increased importance in electrical power applications, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power provided via the photovoltaic conversion process depends on solar irradiation and temperature. Therefore, to maximize the efficiency of the photovoltaic energy system, it is necessary to track the maximum power point of the PV array. The present paper proposes a maximum power point tracker (MPPT) method, based on fuzzy logic controller (FLC), applied to a stand-alone photovoltaic system. It uses a sampling measure of the PV array power and voltage then determines an optimal increment required to have the optimal operating voltage which permits maximum power tracking. This method carries high accuracy around the optimum point when compared to the conventional one. The stand-alone photovoltaic system used in this paper includes two bi-directional DC/DC converters and a lead-acid battery bank to overcome the scare periods. One converter works as an MPP tracker, while the other regulates the batteries state of charge and compensates the power deficit to provide a continuous delivery of energy to the load. The Obtained simulation results show the effectiveness of the proposed fuzzy logic controller.

Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

IceCube Collaboration; Pierre Auger Collaboration; Telescope Array Collaboration

2016-01-01

This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECRmore » magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.« less

Particle displacement tracking applied to air flows

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

1991-01-01

Electronic Particle Image Velocimeter (PIV) techniques offer many advantages over conventional photographic PIV methods such as fast turn around times and simplified data reduction. A new all electronic PIV technique was developed which can measure high speed gas velocities. The Particle Displacement Tracking (PDT) technique employs a single cw laser, small seed particles (1 micron), and a single intensified, gated CCD array frame camera to provide a simple and fast method of obtaining two-dimensional velocity vector maps with unambiguous direction determination. Use of a single CCD camera eliminates registration difficulties encountered when multiple cameras are used to obtain velocity magnitude and direction information. An 80386 PC equipped with a large memory buffer frame-grabber board provides all of the data acquisition and data reduction operations. No array processors of other numerical processing hardware are required. Full video resolution (640x480 pixel) is maintained in the acquired images, providing high resolution video frames of the recorded particle images. The time between data acquisition to display of the velocity vector map is less than 40 sec. The new electronic PDT technique is demonstrated on an air nozzle flow with velocities less than 150 m/s.

Developmental changes in visual short-term memory in infancy: evidence from eye-tracking.

PubMed

Oakes, Lisa M; Baumgartner, Heidi A; Barrett, Frederick S; Messenger, Ian M; Luck, Steven J

2013-01-01

We assessed visual short-term memory (VSTM) for color in 6- and 8-month-old infants (n = 76) using a one-shot change detection task. In this task, a sample array of two colored squares was visible for 517 ms, followed by a 317-ms retention period and then a 3000-ms test array consisting of one unchanged item and one item in a new color. We tracked gaze at 60 Hz while infants looked at the changed and unchanged items during test. When the two sample items were different colors (Experiment 1), 8-month-old infants exhibited a preference for the changed item, indicating memory for the colors, but 6-month-olds exhibited no evidence of memory. When the two sample items were the same color and did not need to be encoded as separate objects (Experiment 2), 6-month-old infants demonstrated memory. These results show that infants can encode information in VSTM in a single, brief exposure that simulates the timing of a single fixation period in natural scene viewing, and they reveal rapid developmental changes between 6 and 8 months in the ability to store individuated items in VSTM.

Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array

DOE PAGES

Aartsen, M. G.

2016-01-20

This study presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECRmore » magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.« less

Stereo and IMU-Assisted Visual Odometry for Small Robots

NASA Technical Reports Server (NTRS)

2012-01-01

This software performs two functions: (1) taking stereo image pairs as input, it computes stereo disparity maps from them by cross-correlation to achieve 3D (three-dimensional) perception; (2) taking a sequence of stereo image pairs as input, it tracks features in the image sequence to estimate the motion of the cameras between successive image pairs. A real-time stereo vision system with IMU (inertial measurement unit)-assisted visual odometry was implemented on a single 750 MHz/520 MHz OMAP3530 SoC (system on chip) from TI (Texas Instruments). Frame rates of 46 fps (frames per second) were achieved at QVGA (Quarter Video Graphics Array i.e. 320 240), or 8 fps at VGA (Video Graphics Array 640 480) resolutions, while simultaneously tracking up to 200 features, taking full advantage of the OMAP3530's integer DSP (digital signal processor) and floating point ARM processors. This is a substantial advancement over previous work as the stereo implementation produces 146 Mde/s (millions of disparities evaluated per second) in 2.5W, yielding a stereo energy efficiency of 58.8 Mde/J, which is 3.75 better than prior DSP stereo while providing more functionality.

Self-adaptive calibration for staring infrared sensors

NASA Astrophysics Data System (ADS)

Kendall, William B.; Stocker, Alan D.

1993-10-01

This paper presents a new, self-adaptive technique for the correlation of non-uniformities (fixed-pattern noise) in high-density infrared focal-plane detector arrays. We have developed a new approach to non-uniformity correction in which we use multiple image frames of the scene itself, and take advantage of the aim-point wander caused by jitter, residual tracking errors, or deliberately induced motion. Such wander causes each detector in the array to view multiple scene elements, and each scene element to be viewed by multiple detectors. It is therefore possible to formulate (and solve) a set of simultaneous equations from which correction parameters can be computed for the detectors. We have tested our approach with actual images collected by the ARPA-sponsored MUSIC infrared sensor. For these tests we employed a 60-frame (0.75-second) sequence of terrain images for which an out-of-date calibration was deliberately used. The sensor was aimed at a point on the ground via an operator-assisted tracking system having a maximum aim point wander on the order of ten pixels. With these data, we were able to improve the calibration accuracy by a factor of approximately 100.

Adaptive DFT-Based Interferometer Fringe Tracking

NASA Astrophysics Data System (ADS)

Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) Observatory at Mount Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three baselines of the Michelson stellar interferometer at IOTA. Based on sliding window discrete Fourier-transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on offline data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. The adaptive DFT-based tracking algorithm should be applicable to other systems where there is a need to detect or track a signal with an approximately constant-frequency carrier pulse. One example of such an application might be to the field of thin-film measurement by ellipsometry, using a broadband light source and a Fourier-transform spectrometer to detect the resulting fringe patterns.

A real-time tracking system of infrared dim and small target based on FPGA and DSP

NASA Astrophysics Data System (ADS)

Rong, Sheng-hui; Zhou, Hui-xin; Qin, Han-lin; Wang, Bing-jian; Qian, Kun

2014-11-01

A core technology in the infrared warning system is the detection tracking of dim and small targets with complicated background. Consequently, running the detection algorithm on the hardware platform has highly practical value in the military field. In this paper, a real-time detection tracking system of infrared dim and small target which is used FPGA (Field Programmable Gate Array) and DSP (Digital Signal Processor) as the core was designed and the corresponding detection tracking algorithm and the signal flow is elaborated. At the first stage, the FPGA obtain the infrared image sequence from the sensor, then it suppresses background clutter by mathematical morphology method and enhances the target intensity by Laplacian of Gaussian operator. At the second stage, the DSP obtain both the original image and the filtered image form the FPGA via the video port. Then it segments the target from the filtered image by an adaptive threshold segmentation method and gets rid of false target by pipeline filter. Experimental results show that our system can achieve higher detection rate and lower false alarm rate.

Growth in the Number of SSN Tracked Orbital Objects

NASA Technical Reports Server (NTRS)

Stansbery, Eugene G.

2004-01-01

The number of objects in earth orbit tracked by the US Space Surveillance Network (SSN) has experienced unprecedented growth since March, 2003. Approximately 2000 orbiting objects have been added to the "Analyst list" of tracked objects. This growth is primarily due to the resumption of full power/full time operation of the AN/FPS-108 Cobra Dane radar located on Shemya Island, AK. Cobra Dane is an L-band (23-cm wavelength) phased array radar which first became operational in 1977. Cobra Dane was a "Collateral Sensor" in the SSN until 1994 when its communication link with the Space Control Center (SCC) was closed. NASA and the Air Force conducted tests in 1999 using Cobra Dane to detect and track small debris. These tests confirmed that the radar was capable of detecting and maintaining orbits on objects as small as 5-cm diameter. Subsequently, Cobra Dane was reconnected to the SSN and resumed full power/full time space surveillance operations on March 4, 2003. This paper will examine the new data and its implications to the understanding of the orbital debris environment and orbital safety.

Adaptive DFT-Based Interferometer Fringe Tracking

NASA Astrophysics Data System (ADS)

Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

2005-12-01

An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) Observatory at Mount Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three baselines of the Michelson stellar interferometer at IOTA. Based on sliding window discrete Fourier-transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on offline data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately [InlineEquation not available: see fulltext.] milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. The adaptive DFT-based tracking algorithm should be applicable to other systems where there is a need to detect or track a signal with an approximately constant-frequency carrier pulse. One example of such an application might be to the field of thin-film measurement by ellipsometry, using a broadband light source and a Fourier-transform spectrometer to detect the resulting fringe patterns.

Investigation of CMOS pixel sensor with 0.18 μm CMOS technology for high-precision tracking detector

NASA Astrophysics Data System (ADS)

Zhang, L.; Fu, M.; Zhang, Y.; Yan, W.; Wang, M.

2017-01-01

The Circular Electron Positron Collider (CEPC) proposed by the Chinese high energy physics community is aiming to measure Higgs particles and their interactions precisely. The tracking detector including Silicon Inner Tracker (SIT) and Forward Tracking Disks (FTD) has driven stringent requirements on sensor technologies in term of spatial resolution, power consumption and readout speed. CMOS Pixel Sensor (CPS) is a promising candidate to approach these requirements. This paper presents the preliminary studies on the sensor optimization for tracking detector to achieve high collection efficiency while keeping necessary spatial resolution. Detailed studies have been performed on the charge collection using a 0.18 μm CMOS image sensor process. This process allows high resistivity epitaxial layer, leading to a significant improvement on the charge collection and therefore improving the radiation tolerance. Together with the simulation results, the first exploratory prototype has bee designed and fabricated. The prototype includes 9 different pixel arrays, which vary in terms of pixel pitch, diode size and geometry. The total area of the prototype amounts to 2 × 7.88 mm2.

GEOS-2 refraction program summary document. [ionospheric and tropospheric propagation errors in satellite tracking instruments

NASA Technical Reports Server (NTRS)

Mallinckrodt, A. J.

1977-01-01

Data from an extensive array of collocated instrumentation at the Wallops Island test facility were intercompared in order to (1) determine the practical achievable accuracy limitations of various tropospheric and ionospheric correction techniques; (2) examine the theoretical bases and derivation of improved refraction correction techniques; and (3) estimate internal systematic and random error levels of the various tracking stations. The GEOS 2 satellite was used as the target vehicle. Data were obtained regarding the ionospheric and tropospheric propagation errors, the theoretical and data analysis of which was documented in some 30 separate reports over the last 6 years. An overview of project results is presented.

Tracking and imaging humans on heterogeneous infrared sensor arrays for law enforcement applications

NASA Astrophysics Data System (ADS)

Feller, Steven D.; Zheng, Y.; Cull, Evan; Brady, David J.

2002-08-01

We present a plan for the integration of geometric constraints in the source, sensor and analysis levels of sensor networks. The goal of geometric analysis is to reduce the dimensionality and complexity of distributed sensor data analysis so as to achieve real-time recognition and response to significant events. Application scenarios include biometric tracking of individuals, counting and analysis of individuals in groups of humans and distributed sentient environments. We are particularly interested in using this approach to provide networks of low cost point detectors, such as infrared motion detectors, with complex imaging capabilities. By extending the capabilities of simple sensors, we expect to reduce the cost of perimeter and site security applications.

Science& Technology Review November 2003

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMahon, D

2003-11-01

This issue of Science & Technology Review covers the following topics: (1) We Will Always Need Basic Science--Commentary by Tomas Diaz de la Rubia; (2) When Semiconductors Go Nano--experiments and computer simulations reveal some surprising behavior of semiconductors at the nanoscale; (3) Retinal Prosthesis Provides Hope for Restoring Sight--A microelectrode array is being developed for a retinal prosthesis; (4) Maglev on the Development Track for Urban Transportation--Inductrack, a Livermore concept to levitate train cars using permanent magnets, will be demonstrated on a 120-meter-long test track; and (5) Power Plant on a Chip Moves Closer to Reality--Laboratory-designed fuel processor gives powermore » boost to dime-size fuel cell.« less

The effects of correlated noise in phased-array observations of radio sources

NASA Technical Reports Server (NTRS)

Dewey, Rachel J.

1994-01-01

Arrays of radio telescopes are now routinely used to provide increased signal-to-noise when observing faint point sources. However, calculation of the achievable sensitivity is complicated if there are sources in the field of view other than the target source. These additional sources not only increase the system temperatures of the individual antennas, but may also contribute significant 'correlated noise' to the effective system temperature of the array. This problem has been of particular interest in the context of tracking spacecraft in the vicinity of radio-bright planets (e.g., Galileo at Jupiter), but it has broader astronomical relevance as well. This paper presents a general formulation of the problem, for the case of a point-like target source in the presence of an additional radio source of arbitrary brightness distribution. We re-derive the well known result that, in the absence of any background sources, a phased array of N indentical antennas is a factor of N more sensitive than a single antenna. We also show that an unphased array of N identical antennas is, on average, no more sensitive than a single antenna if the signals from the individual antennas are combined prior to detection. In the case where a background source is present we show that the effects of correlated noise are highly geometry dependent, and for some astronomical observations may cause significant fluctuations in the array's effective system temperature.

Simulacrum or Corporeal Manifestations in Antarctic Muon and Neutrino Detector Array

NASA Astrophysics Data System (ADS)

Liubarsky, Igor Romanovic

To date, Antarctic Muon and Neutrino Detector Array (AMANDA) collaboration has successfully deployed 382 optical modules at various depths in the South Polar ice sheet. The last 216 optical modules were put in place during the 1996-7 austral summer. This deployment completed a 10-stringed detector at depth between 1500-2000m (AMANDA-B). The detector has been operating successfully and taking data at a rate of 92Hz. However, due to the remoteness of location and the limited bandwidth for satellite transmission, only 5% of the latest data can be transmitted from the South Pole to the collaboration. Before the end of the 1996-7 antarctic season 6GBytes of data were carried to the rest of the world by hand. Since this data was taken while detector calibration was still being performed, it is far from ideal. Yet this sample, to date, represents the largest amount of the data taken by the 10 string detector available for analysis. A total of 11.8 hours of raw data was analysed, comprising 3,380,739 events. Of that number 2,951,118 were AMANDA-B triggers. After calibration and noise cleaning, the number of confirmed AMANDA-B triggers was further reduced to 2,880,391. From this data set a fraction of events were reconstructed without any filtering on the reconstructed direction of the final track. This resulted in 103,168 reconstructed tracks from all zenith angles. However, the full set of 2,880,391 triggers was used to reconstruct tracks, selecting only those that yielded an up-going muon. The procedure produced 25,122 tracks. Various quality criteria was then utilised to discriminate real up-going tracks from fake events mimicked by down-going muons. No real up-going events were found. My personal contribution to the AMANDA experiment has been in three main areas: hardware; I have built 40 of the first AMANDA-A modules; software; I have written subroutines for the University of Wisconsin-Madison AMANDA group's Monte Carlo; data analysis; I have analysed the early 10 string AMANDA-B data.

Twelve years of tracking 52-Hz whale calls from a unique source in the North Pacific

NASA Astrophysics Data System (ADS)

Watkins, William A.; Daher, Mary Ann; George, Joseph E.; Rodriguez, David

2004-12-01

A unique whale call with 50-52 Hz emphasis from a single source has been tracked over 12 years in the central and eastern North Pacific. These calls, referred to as 52-Hz calls, were monitored and analyzed from acoustic data recorded by hydrophones of the US Navy Sound Surveillance System (SOSUS) and other arrays. The calls were noticed first in 1989, and have been detected and tracked since 1992. No other calls with similar characteristics have been identified in the acoustic data from any hydrophone system in the North Pacific basin. Only one series of these 52-Hz calls has been recorded at a time, with no call overlap, suggesting that a single whale produced the calls. The calls were recorded from August to February with most in December and January. The species producing these calls is unknown. The tracks of the 52-Hz whale were different each year, and varied in length from 708 to 11,062 km with travel speeds ranging from 0.7 to 3.8 km/h. Tracks included (A) meandering over short ranges, (B) predominantly west-to-east movement, and (C) mostly north-to-south travel. These tracks consistently appeared to be unrelated to the presence or movement of other whale species (blue, fin and humpback) monitored year-round with the same hydrophones.

Method for dose-reduced 3D catheter tracking on a scanning-beam digital x-ray system using dynamic electronic collimation

NASA Astrophysics Data System (ADS)

Dunkerley, David A. P.; Funk, Tobias; Speidel, Michael A.

2016-03-01

Scanning-beam digital x-ray (SBDX) is an inverse geometry x-ray fluoroscopy system capable of tomosynthesis-based 3D catheter tracking. This work proposes a method of dose-reduced 3D tracking using dynamic electronic collimation (DEC) of the SBDX scanning x-ray tube. Positions in the 2D focal spot array are selectively activated to create a regionof- interest (ROI) x-ray field around the tracked catheter. The ROI position is updated for each frame based on a motion vector calculated from the two most recent 3D tracking results. The technique was evaluated with SBDX data acquired as a catheter tip inside a chest phantom was pulled along a 3D trajectory. DEC scans were retrospectively generated from the detector images stored for each focal spot position. DEC imaging of a catheter tip in a volume measuring 11.4 cm across at isocenter required 340 active focal spots per frame, versus 4473 spots in full-FOV mode. The dose-area-product (DAP) and peak skin dose (PSD) for DEC versus full field-of-view (FOV) scanning were calculated using an SBDX Monte Carlo simulation code. DAP was reduced to 7.4% to 8.4% of the full-FOV value, consistent with the relative number of active focal spots (7.6%). For image sequences with a moving catheter, PSD was 33.6% to 34.8% of the full-FOV value. The root-mean-squared-deviation between DEC-based 3D tracking coordinates and full-FOV 3D tracking coordinates was less than 0.1 mm. The 3D distance between the tracked tip and the sheath centerline averaged 0.75 mm. Dynamic electronic collimation can reduce dose with minimal change in tracking performance.

Advanced Precipitation Radar Antenna to Measure Rainfall From Space

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Yahya; Lin, John; Huang, John; Im, Eastwood; Lou, Michael; Lopez, Bernardo; Durden, Stephen

2008-01-01

To support NASA s planned 20-year mission to provide sustained global precipitation measurement (EOS-9 Global Precipitation Measurement (GPM)), a deployable antenna has been explored with an inflatable thin-membrane structure. This design uses a 5.3 5.3-m inflatable parabolic reflector with the electronically scanned, dual-frequency phased array feeds to provide improved rainfall measurements at 2.0-km horizontal resolution over a cross-track scan range of up to 37 , necessary for resolving intense, isolated storm cells and for reducing the beam-filling and spatial sampling errors. The two matched radar beams at the two frequencies (Ku and Ka bands) will allow unambiguous retrieval of the parameters in raindrop size distribution. The antenna is inflatable, using rigidizable booms, deployable chain-link supports with prescribed curvatures, a smooth, thin-membrane reflecting surface, and an offset feed technique to achieve the precision surface tolerance (0.2 mm RMS) for meeting the low-sidelobe requirement. The cylindrical parabolic offset-feed reflector augmented with two linear phased array feeds achieves dual-frequency shared-aperture with wide-angle beam scanning and very low sidelobe level of -30 dB. Very long Ku and Ka band microstrip feed arrays incorporating a combination of parallel and series power divider lines with cosine-over-pedestal distribution also augment the sidelobe level and beam scan. This design reduces antenna mass and launch vehicle stowage volume. The Ku and Ka band feed arrays are needed to achieve the required cross-track beam scanning. To demonstrate the inflatable cylindrical reflector with two linear polarizations (V and H), and two beam directions (0deg and 30deg), each frequency band has four individual microstrip array designs. The Ku-band array has a total of 166x2 elements and the Ka-band has 166x4 elements with both bands having element spacing about 0.65 lambda(sub 0). The cylindrical reflector with offset linear array feeds reduces the complexity from "NxN" transmit/receive (T/R) modules of a conventional planar-phased array to just "N" T/R modules. The antenna uses T/R modules with electronic phase-shifters for beam steering. The offset reflector does not provide poor cross-polarization like a double- curved offset reflector would, and it allows the wide scan angle in one plane required by the mission. Also, the cylindrical reflector with two linear array feeds provides dual-frequency performance with a single, shared aperture. The aperture comprises a reflective surface with a focal length of 1.89 m and is made from aluminized Kapton film. The reflective surface is of uniform thickness in the range of a few thousandths of an inch and is attached to the chain-link support structure via an adjustable suspension system. The film aperture rolls up, together with the chain-link structure, for launch and can be deployed in space by the deployment of the chain-link structure.

Clonal expansion under the microscope: studying lymphocyte activation and differentiation using live-cell imaging.

PubMed

Polonsky, Michal; Chain, Benjamin; Friedman, Nir

2016-03-01

Clonal expansion of lymphocytes is a hallmark of vertebrate adaptive immunity. A small number of precursor cells that recognize a specific antigen proliferate into expanded clones, differentiate and acquire various effector and memory phenotypes, which promote effective immune responses. Recent studies establish a large degree of heterogeneity in the level of expansion and in cell state between and within expanding clones. Studying these processes in vivo, while providing insightful information on the level of heterogeneity, is challenging due to the complex microenvironment and the inability to continuously track individual cells over extended periods of time. Live cell imaging of ex vivo cultures within micro fabricated arrays provides an attractive methodology for studying clonal expansion. These experiments facilitate continuous acquisition of a large number of parameters on cell number, proliferation, death and differentiation state, with single-cell resolution on thousands of expanding clones that grow within controlled environments. Such data can reveal stochastic and instructive mechanisms that contribute to observed heterogeneity and elucidate the sequential order of differentiation events. Intercellular interactions can also be studied within these arrays by following responses of a controlled number of interacting cells, all trapped within the same microwell. Here we describe implementations of live-cell imaging within microwell arrays for studies of lymphocyte clonal expansion, portray insights already gained from these experiments and outline directions for future research. These tools, together with in vivo experiments tracking single-cell responses, will expand our understanding of adaptive immunity and the ways by which it can be manipulated.

Magnetic field mapping of the UCNTau magneto-gravitational trap: design study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libersky, Matthew Murray

2014-09-04

The beta decay lifetime of the free neutron is an important input to the Standard Model of particle physics, but values measured using different methods have exhibited substantial disagreement. The UCN r experiment in development at Los Alamos National Laboratory (LANL) plans to explore better methods of measuring the neutron lifetime using ultracold neutrons (UCNs). In this experiment, UCNs are confined in a magneto-gravitational trap formed by a curved, asymmetric Halbach array placed inside a vacuum vessel and surrounded by holding field coils. If any defects present in the Halbach array are sufficient to reduce the local field near themore » surface below that needed to repel the desired energy level UCNs, loss by material interaction can occur at a rate similar to the loss by beta decay. A map of the magnetic field near the surface of the array is necessary to identify any such defects, but the array's curved geometry and placement in a vacuum vessel make conventional field mapping methods difficult. A system consisting of computer vision-based tracking and a rover holding a Hall probe has been designed to map the field near the surface of the array, and construction of an initial prototype has begun at LANL. The design of the system and initial results will be described here.« less

Rotational displacement skills in rhesus macaques (Macaca mulatta).

PubMed

Hughes, Kelly D; Santos, Laurie R

2012-11-01

Rotational displacement tasks, in which participants must track an object at a hiding location within an array while the array rotates, exhibit a puzzling developmental pattern in humans. Human children take an unusually long time to master this task and tend to solve rotational problems through the use of nongeometric features or landmarks as opposed to other kinds of spatial cues. We investigated whether these developmental characteristics are unique to humans by testing rotational displacement skills in a monkey species, the rhesus macaque (Macaca mulatta), using a looking-time method. Monkeys first saw food hidden in two differently colored boxes within an array. The array was then rotated 180° and the boxes reopened to reveal the food in an expected or unexpected location. Our first two experiments explored the developmental time-course of performance on this rotational displacement task. We found that adult macaques looked longer at the unexpected event, but such performance was not mirrored in younger-aged macaques. In a third study, we systematically varied featural information and visible access to the array to investigate which strategies adult macaques used in solving rotational displacements. Our results show that adult macaques need both sets of information to solve the task. Taken together, these results suggest both similarities and differences in mechanisms by which human and nonhuman primates develop this spatial skill.

Ground-Truthing a Next Generation Snow Radar

NASA Astrophysics Data System (ADS)

Yan, S.; Brozena, J. M.; Gogineni, P. S.; Abelev, A.; Gardner, J. M.; Ball, D.; Liang, R.; Newman, T.

2016-12-01

During the early spring of 2016 the Naval Research Laboratory (NRL) performed a test of a next generation airborne snow radar over ground truth data collected on several areas of fast ice near Barrow, AK. The radar was developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, and includes several improvements compared to their previous snow radar. The new unit combines the earlier Ku-band and snow radars into a single unit with an operating frequency spanning the entire 2-18 GHz, an enormous bandwidth which provides the possibility of snow depth measurements with 1.5 cm range resolution. Additionally, the radar transmits on dual polarizations (H and V), and receives the signal through two orthogonally polarized Vivaldi arrays, each with 128 phase centers. The 8 sets of along-track phase centers are combined in hardware to improve SNR and narrow the beamwidth in the along-track, resulting in 8 cross-track effective phase centers which are separately digitized to allow for beam sharpening and forming in post-processing. Tilting the receive arrays 30 degrees from the horizontal also allows the formation of SAR images and the potential for estimating snow-water equivalent (SWE). Ground truth data (snow depth, density, salinity and SWE) were collected over several 60 m wide swaths that were subsequently overflown with the snow radar mounted on a Twin Otter. The radar could be operated in nadir (by beam steering the receive antennas to point beneath the aircraft) or side-looking modes. Results from the comparisons will be shown.

A highly scalable particle tracking algorithm using partitioned global address space (PGAS) programming for extreme-scale turbulence simulations

NASA Astrophysics Data System (ADS)

Buaria, D.; Yeung, P. K.

2017-12-01

A new parallel algorithm utilizing a partitioned global address space (PGAS) programming model to achieve high scalability is reported for particle tracking in direct numerical simulations of turbulent fluid flow. The work is motivated by the desire to obtain Lagrangian information necessary for the study of turbulent dispersion at the largest problem sizes feasible on current and next-generation multi-petaflop supercomputers. A large population of fluid particles is distributed among parallel processes dynamically, based on instantaneous particle positions such that all of the interpolation information needed for each particle is available either locally on its host process or neighboring processes holding adjacent sub-domains of the velocity field. With cubic splines as the preferred interpolation method, the new algorithm is designed to minimize the need for communication, by transferring between adjacent processes only those spline coefficients determined to be necessary for specific particles. This transfer is implemented very efficiently as a one-sided communication, using Co-Array Fortran (CAF) features which facilitate small data movements between different local partitions of a large global array. The cost of monitoring transfer of particle properties between adjacent processes for particles migrating across sub-domain boundaries is found to be small. Detailed benchmarks are obtained on the Cray petascale supercomputer Blue Waters at the University of Illinois, Urbana-Champaign. For operations on the particles in a 81923 simulation (0.55 trillion grid points) on 262,144 Cray XE6 cores, the new algorithm is found to be orders of magnitude faster relative to a prior algorithm in which each particle is tracked by the same parallel process at all times. This large speedup reduces the additional cost of tracking of order 300 million particles to just over 50% of the cost of computing the Eulerian velocity field at this scale. Improving support of PGAS models on major compilers suggests that this algorithm will be of wider applicability on most upcoming supercomputers.

Roadmap for searching cosmic rays correlated with the extraterrestrial neutrinos seen at IceCube

NASA Astrophysics Data System (ADS)

Carpio, J. A.; Gago, A. M.

2017-06-01

We have built sky maps showing the expected arrival directions of 120 EeV ultrahigh-energy cosmic rays (UHECRs) directionally correlated with the latest astrophysical neutrino tracks observed at IceCube, including the four-year high-energy starting events (HESEs) and the two-year northern tracks, taken as point sources. We have considered contributions to UHECR deflections from the Galactic and the extragalactic magnetic field and a UHECR composition compatible with the current expectations. We have used the Jansson-Farrar JF12 model for the Galactic magnetic field and an extragalactic magnetic field strength of 1 nG and coherence length of 1 Mpc. We observe that the regions outside of the Galactic plane are more strongly correlated with the neutrino tracks than those adjacent to or in it, where IceCube HESE events 37 and 47 are good candidates to search for excesses, or anisotropies, in the UHECR flux. On the other hand, clustered northern tracks around (l ,b )=(0 ° ,-3 0 ° ) and (l ,b )=(-15 0 ° ,-3 0 ° ) are promising candidates for a stacked point source search. For example, we have focused on the region of UHECR arrival directions, at 150 EeV, correlated with IceCube HESE event 37 located at (l ,b )=(-137.1 ° ,65.8 ° ) in the northern hemisphere, far away from the Galactic plane, obtaining an angular size ˜5 ° , being ˜3 ° for 200 EeV and ˜8 ° for 120 EeV. We report a p value of 0.20 for a stacked point source search using current Auger and Telescope Array data, consistent with current results from both collaborations. Using Telescope Array data alone, we found a projected live time of 72 years to find correlations, but clearly this must improve with the planned Auger upgrade.

Multipurpose active pixel sensor (APS)-based microtracker

NASA Astrophysics Data System (ADS)

Eisenman, Allan R.; Liebe, Carl C.; Zhu, David Q.

1998-12-01

A new, photon-sensitive, imaging array, the active pixel sensor (APS) has emerged as a competitor to the CCD imager for use in star and target trackers. The Jet Propulsion Laboratory (JPL) has undertaken a program to develop a new generation, highly integrated, APS-based, multipurpose tracker: the Programmable Intelligent Microtracker (PIM). The supporting hardware used in the PIM has been carefully selected to enhance the inherent advantages of the APS. Adequate computation power is included to perform star identification, star tracking, attitude determination, space docking, feature tracking, descent imaging for landing control, and target tracking capabilities. Its first version uses a JPL developed 256 X 256-pixel APS and an advanced 32-bit RISC microcontroller. By taking advantage of the unique features of the APS/microcontroller combination, the microtracker will achieve about an order-of-magnitude reduction in mass and power consumption compared to present state-of-the-art star trackers. It will also add the advantage of programmability to enable it to perform a variety of star, other celestial body, and target tracking tasks. The PIM is already proving the usefulness of its design concept for space applications. It is demonstrating the effectiveness of taking such an integrated approach in building a new generation of high performance, general purpose, tracking instruments to be applied to a large variety of future space missions.

A binary link tracker for the BaBar level 1 trigger system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berenyi, A.; Chen, H.K.; Dao, K.

1999-08-01

The BaBar detector at PEP-II will operate in a high-luminosity e{sup +}e{sup {minus}} collider environment near the {Upsilon}(4S) resonance with the primary goal of studying CP violation in the B meson system. In this environment, typical physics events of interest involve multiple charged particles. These events are identified by counting these tracks in a fast first level (Level 1) trigger system, by reconstructing the tracks in real time. For this purpose, a Binary Link Tracker Module (BLTM) was designed and fabricated for the BaBar Level 1 Drift Chamber trigger system. The BLTM is responsible for linking track segments, constructed bymore » the Track Segment Finder Modules (TSFM), into complete tracks. A single BLTM module processes a 360 MBytes/s stream of segment hit data, corresponding to information from the entire Drift Chamber, and implements a fast and robust algorithm that tolerates high hit occupancies as well as local inefficiencies of the Drift Chamber. The algorithms and the necessary control logic of the BLTM were implemented in Field Programmable Gate Arrays (FPGAs), using the VHDL hardware description language. The finished 9U x 400 mm Euro-format board contains roughly 75,000 gates of programmable logic or about 10,000 lines of VHDL code synthesized into five FPGAs.« less

Maximum-likelihood-based extended-source spatial acquisition and tracking for planetary optical communications

NASA Astrophysics Data System (ADS)

Tsou, Haiping; Yan, Tsun-Yee

1999-04-01

This paper describes an extended-source spatial acquisition and tracking scheme for planetary optical communications. This scheme uses the Sun-lit Earth image as the beacon signal, which can be computed according to the current Sun-Earth-Probe angle from a pre-stored Earth image or a received snapshot taken by other Earth-orbiting satellite. Onboard the spacecraft, the reference image is correlated in the transform domain with the received image obtained from a detector array, which is assumed to have each of its pixels corrupted by an independent additive white Gaussian noise. The coordinate of the ground station is acquired and tracked, respectively, by an open-loop acquisition algorithm and a closed-loop tracking algorithm derived from the maximum likelihood criterion. As shown in the paper, the optimal spatial acquisition requires solving two nonlinear equations, or iteratively solving their linearized variants, to estimate the coordinate when translation in the relative positions of onboard and ground transceivers is considered. Similar assumption of linearization leads to the closed-loop spatial tracking algorithm in which the loop feedback signals can be derived from the weighted transform-domain correlation. Numerical results using a sample Sun-lit Earth image demonstrate that sub-pixel resolutions can be achieved by this scheme in a high disturbance environment.

Prospects for tracking spacecrafts within 2 million Km of Earth with phased array antennas

NASA Technical Reports Server (NTRS)

Amoozegar, F.; Jamnejad, V.; Cesarone, R.

2003-01-01

Recent advances in space technology for Earth observations, global communications, and positioning systems have created heavy traffic at a variety of orbits. These include smart sensors in low Earth orbits (LEO), internet satellites in LEO and GEO orbits, Earth observing satellites in high Earth orbits (HEO), observatory class satellites at Lagrangian libration points, and those heading for deep space.

TDRS-M Live Launch Coverage

NASA Image and Video Library

2017-08-18

Live launch coverage of the Tracking and Data Relay Satellite, TDRS-M, liftoff at 8:39am EDT from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. TDRS-M is the latest spacecraft destined for the agency's constellation of communications satellites that allows nearly continuous contact with orbiting spacecraft ranging from the International Space Station and Hubble Space Telescope to the array of scientific observatories.

Criterion 6: Maintenance and enhancement of long-term multiple socioeconomic benefits to meet the needs of societies

Treesearch

Stephen R. Shifley; Francisco X. Aguilar; Nianfu Song; Susan I. Stewart; David J. Nowak; Dale D. Gormanson; W. Keith Moser; Sherri Wormstead; Eric J. Greenfield

2012-01-01

Forests provide an array of products and services that maintain and enhance benefits to our society and economy. Benefits derived from forests may be categorized into wood products, nontimber products and services, and ecosystem services. The value and volume of these products and services indicate the importance of forests for a wide variety of uses.Tracking values,...

The Radar Roadmap

DTIC Science & Technology

2013-01-01

local oscillator to measure the phase of both the transmitted and received pulses and then matching them to the correct range ambiguity. 2.5 High...track closely spaced objects. White Sands Missile Range (WSMR) and Patrick Air Force Base (AFB) operate the phased -array AN/MPS-39 MOTRs. The...ABERDEEN TEST CENTER DUGWAY PROVING GROUND REAGAN TEST SITE YUMA PROVING GROUND WHITE SANDS MISSILE RANGE NAVAL AIR WARFARE CENTER AIRCRAFT

Milestones Toward 50% Efficient Solar Cell Modules

DTIC Science & Technology

2007-09-01

efficiency, both at solar cells and module level. The optical system consists of a tiled nonimaging concentrating system, coupled with a spectral...which combines a nonimaging optical concentrator (which does not require tracking and is called a static concentrator) with spectral splitting...DESIGN AND RESULTS The optical design is based on non-symmetric, nonimaging optics, tiled into an array. The central issues in the optical system

Status of the development of Brazilian Decimetric Array (BDA)

NASA Astrophysics Data System (ADS)

Sawant, Hanumant; Fernandes, Francisco; Chellasamy, Ebenezer; Cecatto, Jose R.; Costa, D. Joaquim; Sirothia, Sandeep Kumar; Subramanian, Koovapady

BDA will consists of 38 antennas of 4 meters diameter, capable of operating at frequency range of (1.2-1.7, 2.8 and 5.6) GHz. The array will be spread over the distances 2 x 1 km in a T shape with longest base line in E-W direction, having spatial resolution of ~10 sec of arc at 5.6 GHz. The visibility data can be processed to provide two dimensional images at a time resolution of 100 ms (or higher). In the second phase of the BDA, almost all systems of the 26 antennas are installed. LO of 10 MHz is send from receiver room to each receiver located in the each antenna tower. This receiver operates in the frequency range of 1-6 GHz and converts received signal to 70 MHz. Fiber optical system is partially installed in tower converts 70 MHz signal to optical signal and send to receiver room with low loss and phase compensation of 100 ps, where it is converted back to 70 MHz and processed to give output of 0-5 MHz bandpass and further processed by the correlator. Tracking system, with Dual feed back facility has tracking accuracy of +/- 3 arc minutes. All safety features are installed, with on line offset adjustment. Data logging and event logging for future investigations are available. Tracking system was tested for one month with 8 hours tracking and results of these will also be presented. Field programmable Gate Array based complex correlator system capable of producing all four Stokes parameters was designed and developed for correlating base band outputs from 38 antennas. The correlator produces delay and fringe corrected, visibility correlations between any two signal channels of the same polarizations from any given pair of antennas, providing visibility data. Fringes using this system have been obtained for baseline combinations of 12 fully installed antennas. Simulations of the UV coverage and imaging were carried out for the full synthesis observations of sources at different configurations and various declinations in -70 to +23 degrees range. The current system can image the Sun with spatial resolution of 3.40 x 4.54 arc min at 1.4 GHz. Results of the each of the above systems along with the observed fringes from the FPGA based complex correlator system from non redundant 12 antennas in two dimensions will be presented. BDA phase II will be operational shortly.

KSC-00pp1626

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, Fla. -- Viewed from across the turn basin at KSC, Space Shuttle Endeavour inches its way to Launch Pad 39B via the crawlerway that leads from the Vehicle Assembly Building. The Shuttle is on the Mobile Launcher Platform (MLP) which is atop the crawler-transporter, moving on four double-tracked crawlers. The maximum speed of the loaded transporter is 1 mph. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

KSC00padig053

NASA Image and Video Library

2000-10-31

KENNEDY SPACE CENTER, Fla. -- Viewed across the turn basin from the Press mound, Space Shuttle Endeavour inches its way to Launch Pad 39B (on the horizon) via the crawlerway that leads from the Vehicle Assembly Building. The Shuttle is on the Mobile Launcher Platform (MLP) which is atop the crawler-transporter, moving on four double-tracked crawlers. The maximum speed of the loaded transporter is 1 mph. Endeavour is scheduled to be launched Nov. 30 at 10:01 p.m. EST on mission STS-97, the sixth construction flight to the International Space Station. Its payload includes the P6 Integrated Truss Structure and a photovoltaic (PV) module, with giant solar arrays that will provide power to the Station. The mission includes two spacewalks to complete the solar array connections

Signaling and sensory adaptation in Escherichia coli chemoreceptors: 2015 update

PubMed Central

Parkinson, John S.; Hazelbauer, Gerald L.; Falke, Joseph J.

2015-01-01

Motile Escherichia coli cells track gradients of attractant and repellent chemicals in their environment with transmembrane chemoreceptor proteins. These receptors operate in cooperative arrays to produce large changes in the activity of a signaling kinase CheA in response to small changes in chemoeffector concentration. Recent research has provided much deeper understanding of the structure and function of core receptor signaling complexes and the architecture of higher-order receptor arrays, which in turn has led to new insights into the molecular signaling mechanisms of chemoreceptor networks. Current evidence supports a new view of receptor signaling in which stimulus information travels within receptor molecules through shifts in the dynamic properties of adjoining structural elements rather than through a few discrete conformational states. PMID:25834953

Detection technique of targets for missile defense system

NASA Astrophysics Data System (ADS)

Guo, Hua-ling; Deng, Jia-hao; Cai, Ke-rong

2009-11-01

Ballistic missile defense system (BMDS) is a weapon system for intercepting enemy ballistic missiles. It includes ballistic-missile warning system, target discrimination system, anti-ballistic-missile guidance systems, and command-control communication system. Infrared imaging detection and laser imaging detection are widely used in BMDS for surveillance, target detection, target tracking, and target discrimination. Based on a comprehensive review of the application of target-detection techniques in the missile defense system, including infrared focal plane arrays (IRFPA), ground-based radar detection technology, 3-dimensional imaging laser radar with a photon counting avalanche photodiode (APD) arrays and microchip laser, this paper focuses on the infrared and laser imaging detection techniques in missile defense system, as well as the trends for their future development.

The Solar Array Photovoltaic Assembly for the INSAT 4CR Spacecraft Design, Development and In-Orbit Performance

NASA Astrophysics Data System (ADS)

Thomas, Joseph; Sudhakar, M.; Agarwal, Anil; Sankaran, M.; Mudramachary, P.

2008-09-01

The INSAT 4CR spacecraft, the third in the INSAT 4 series of Indian Space Research Organization (ISRO)'s Communication satellite program, is a high power communication satellite in Geo- stationary Earth Orbit (GEO), configured using the ISRO I2K bus. The primary power is provided by two-wing sun tracking, deployable solar array and the eclipse load requirement is supported by two 70 Ah nickel hydrogen batteries. The power output of the solar array is regulated by Sequential Switching Shunt Regulators to 42V±0.5V. The salient feature of the solar array design is that it uses the new generation multi junction solar cells for all the four panels of size 2.54m x 1.525m to meet the higher power requirement with the available array area. The solar panel fabrication process with the Advanced Triple Junction (ATJ) solar cells from M/s. EMCORE, USA, has been demonstrated for the GEO life cycle through qualification coupon fabrication and testing.This paper describes the INSAT 4CR solar array photovoltaic assemblies design, layout optimization and realization of the Flight Model (FM) panels. It focuses on the power generation prediction, electrical performance measurement under Large Area Pulsed Sun Simulator (LAPSS) and verification of the ground level test results. The indigenously built Geostationary Launch Vehicle (GSLV F04) has successfully launched the INSAT 4CR spacecraft into the orbit on September 2nd, 2007. This paper also presents the analysis of telemetry data to validate the initial phase in-orbit performance of the solar array with prediction.

Development of HgCdTe large format MBE arrays and noise-free high speed MOVPE EAPD arrays for ground based NIR astronomy

NASA Astrophysics Data System (ADS)

Finger, G.; Baker, I.; Downing, M.; Alvarez, D.; Ives, D.; Mehrgan, L.; Meyer, M.; Stegmeier, J.; Weller, H. J.

2017-11-01

Large format near infrared HgCdTe 2Kx2K and 4Kx4K MBE arrays have reached a level of maturity which meets most of the specifications required for near infrared (NIR) astronomy. The only remaining problem is the persistence effect which is device specific and not yet fully under control. For ground based multi-object spectroscopy on 40 meter class telescopes larger pixels would be advantageous. For high speed near infrared fringe tracking and wavefront sensing the only way to overcome the CMOS noise barrier is the amplification of the photoelectron signal inside the infrared pixel by means of the avalanche gain. A readout chip for a 320x256 pixel HgCdTe eAPD array will be presented which has 32 parallel video outputs being arranged in such a way that the full multiplex advantage is also available for small sub-windows. In combination with the high APD gain this allows reducing the readout noise to the subelectron level by applying nondestructive readout schemes with subpixel sampling. Arrays grown by MOVPE achieve subelectron readout noise and operate with superb cosmetic quality at high APD gain. Efforts are made to reduce the dark current of those arrays to make this technology also available for large format focal planes of NIR instruments offering noise free detectors for deep exposures. The dark current of the latest MOVPE eAPD arrays is already at a level adequate for noiseless broad and narrow band imaging in scientific instruments.

Applications of airborne ultrasound in human-computer interaction.

PubMed

Dahl, Tobias; Ealo, Joao L; Bang, Hans J; Holm, Sverre; Khuri-Yakub, Pierre

2014-09-01

Airborne ultrasound is a rapidly developing subfield within human-computer interaction (HCI). Touchless ultrasonic interfaces and pen tracking systems are part of recent trends in HCI and are gaining industry momentum. This paper aims to provide the background and overview necessary to understand the capabilities of ultrasound and its potential future in human-computer interaction. The latest developments on the ultrasound transducer side are presented, focusing on capacitive micro-machined ultrasonic transducers, or CMUTs. Their introduction is an important step toward providing real, low-cost multi-sensor array and beam-forming options. We also provide a unified mathematical framework for understanding and analyzing algorithms used for ultrasound detection and tracking for some of the most relevant applications. Copyright © 2014. Published by Elsevier B.V.

Comparison and Analysis of Instruments Measuring Plane-of-Array Irradiance for One-Axis Tracking Systems: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dooraghi, Michael R; Sengupta, Manajit; Vignola, Frank

A variety of sensors are studied on a one-axis tracking surface and a horizontal surface in Golden, Colorado, and Eugene, Oregon. This is the first year of a long-term study that will look at not only a comparison between the instruments but also the longer-term degradation in calibration and/or performance. Initially, results from each location will be analyzed, and then results will be compared and contrasted between the two locations. A quick comparison at Eugene indicates that reference solar cells seem to compare better against a secondary standard pyranometer on a one-axis tracker than photodiode-based pyranometers. More study is neededmore » to characterize and confirm this finding.« less

The Tracking Resonance Frequency Method for Photoacoustic Measurements Based on the Phase Response

NASA Astrophysics Data System (ADS)

Suchenek, Mariusz

2017-04-01

One of the major issues in the use of the resonant photoacoustic cell is the resonance frequency of the cell. The frequency is not stable, and its changes depend mostly on temperature and gas mixture. This paper presents a new method for tracking resonance frequency, where both the amplitude and phase are calculated from the input samples. The stimulating frequency can be adjusted to the resonance frequency of the cell based on the phase. This method was implemented using a digital measurement system with an analog to digital converter, field programmable gate array (FPGA) and a microcontroller. The resonance frequency was changed by the injection of carbon dioxide into the cell. A theoretical description and experimental results are also presented.

Per-Pixel, Dual-Counter Scheme for Optical Communications

NASA Technical Reports Server (NTRS)

Farr, William H.; Bimbaum, Kevin M.; Quirk, Kevin J.; Sburlan, Suzana; Sahasrabudhe, Adit

2013-01-01

Free space optical communications links from deep space are projected to fulfill future NASA communication requirements for 2020 and beyond. Accurate laser-beam pointing is required to achieve high data rates at low power levels.This innovation is a per-pixel processing scheme using a pair of three-state digital counters to implement acquisition and tracking of a dim laser beacon transmitted from Earth for pointing control of an interplanetary optical communications system using a focal plane array of single sensitive detectors. It shows how to implement dim beacon acquisition and tracking for an interplanetary optical transceiver with a method that is suitable for both achieving theoretical performance, as well as supporting additional functions of high data rate forward links and precision spacecraft ranging.

An Investigation into the Poor Survival of an Endangered Coho Salmon Population

PubMed Central

Chittenden, Cedar M.; Melnychuk, Michael C.; Welch, David W.; McKinley, R. Scott

2010-01-01

To investigate reasons for the decline of an endangered population of coho salmon (O. kisutch), 190 smolts were acoustically tagged during three consecutive years and their movements and survival were estimated using the Pacific Ocean Shelf Tracking project (POST) array. Median travel times of the Thompson River coho salmon smolts to the lower Fraser River sub-array were 16, 12 and 10 days during 2004, 2005 and 2006, respectively. Few smolts were recorded on marine arrays. Freshwater survival rates of the tagged smolts during their downstream migration were 0.0–5.6% (0.0–9.0% s.e.) in 2004, 7.0% (6.2% s.e.) in 2005, and 50.9% (18.6% s.e.) in 2006. Overall smolt-to-adult return rates exhibited a similar pattern, which suggests that low freshwater survival rates of out-migrating smolts may be a primary reason for the poor conservation status of this endangered coho salmon population. PMID:20526367

Microelectrode Array Microscopy: Investigation of Dynamic Behavior of Localized Corrosion at Type 304 Stainless Steel Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tedd E. Lister; Patrick J. Pinhero

2005-03-01

Scanning electrochemical microscopy (SECM) and a recently developed microelectrode array microscope have been used to study localized corrosion and electron-transfer characteristics of native oxide layers of type 304 stainless steels. The I-/I3- redox couple was employed as a mediator and allowed sensitive detection of oxide breakdown events. In solutions containing I-, a signal at the microelectrode was observed on type 304 stainless steel surfaces at active pitting corrosion sites. Under conditions where pitting corrosion occurs, SECM was used to track the temporal characteristics of the reaction in a spatial manner. However, because of the time required to create an image,more » much of the temporal information was not obtained. To improve the temporal resolution of the measurement, microelectrode array microscopy (MEAM) was developed as a parallel method of performing SECM. The demonstration shown reveals the potential of MEAM for analysis of surface chemistry on temporal and spatial domains.« less

Particle sorting by Paramecium cilia arrays.

PubMed

Mayne, Richard; Whiting, James G H; Wheway, Gabrielle; Melhuish, Chris; Adamatzky, Andrew

Motile cilia are cell-surface organelles whose purposes, in ciliated protists and certain ciliated metazoan epithelia, include generating fluid flow, sensing and substance uptake. Certain properties of cilia arrays, such as beating synchronisation and manipulation of external proximate particulate matter, are considered emergent, but remain incompletely characterised despite these phenomena having being the subject of extensive modelling. This study constitutes a laboratory experimental characterisation of one of the emergent properties of motile cilia: manipulation of adjacent particulates. The work demonstrates through automated videomicrographic particle tracking that interactions between microparticles and somatic cilia arrays of the ciliated model organism Paramecium caudatum constitute a form of rudimentary 'sorting'. Small particles are drawn into the organism's proximity by cilia-induced fluid currents at all times, whereas larger particles may be held immobile at a distance from the cell margin when the cell generates characteristic feeding currents in the surrounding media. These findings can contribute to the design and fabrication of biomimetic cilia, with potential applications to the study of ciliopathies. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-invasive, transdermal, path-selective and specific glucose monitoring via a graphene-based platform

NASA Astrophysics Data System (ADS)

Lipani, Luca; Dupont, Bertrand G. R.; Doungmene, Floriant; Marken, Frank; Tyrrell, Rex M.; Guy, Richard H.; Ilie, Adelina

2018-06-01

Currently, there is no available needle-free approach for diabetics to monitor glucose levels in the interstitial fluid. Here, we report a path-selective, non-invasive, transdermal glucose monitoring system based on a miniaturized pixel array platform (realized either by graphene-based thin-film technology, or screen-printing). The system samples glucose from the interstitial fluid via electroosmotic extraction through individual, privileged, follicular pathways in the skin, accessible via the pixels of the array. A proof of principle using mammalian skin ex vivo is demonstrated for specific and `quantized' glucose extraction/detection via follicular pathways, and across the hypo- to hyper-glycaemic range in humans. Furthermore, the quantification of follicular and non-follicular glucose extraction fluxes is clearly shown. In vivo continuous monitoring of interstitial fluid-borne glucose with the pixel array was able to track blood sugar in healthy human subjects. This approach paves the way to clinically relevant glucose detection in diabetics without the need for invasive, finger-stick blood sampling.

Micro Cantilever Movement Detection with an Amorphous Silicon Array of Position Sensitive Detectors

PubMed Central

Contreras, Javier; Costa, Daniel; Pereira, Sonia; Fortunato, Elvira; Martins, Rodrigo; Wierzbicki, Rafal; Heerlein, Holger; Ferreira, Isabel

2010-01-01

The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30 μm wide by 400 μm long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3%, a spatial resolution of less than 2 μm along the lateral dimension of the sensor as well as of less than 3 μm along the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1 μm when detecting the holding structure. PMID:22163648

Triboelectrification based motion sensor for human-machine interfacing.

PubMed

Yang, Weiqing; Chen, Jun; Wen, Xiaonan; Jing, Qingshen; Yang, Jin; Su, Yuanjie; Zhu, Guang; Wu, Wenzuo; Wang, Zhong Lin

2014-05-28

We present triboelectrification based, flexible, reusable, and skin-friendly dry biopotential electrode arrays as motion sensors for tracking muscle motion and human-machine interfacing (HMI). The independently addressable, self-powered sensor arrays have been utilized to record the electric output signals as a mapping figure to accurately identify the degrees of freedom as well as directions and magnitude of muscle motions. A fast Fourier transform (FFT) technique was employed to analyse the frequency spectra of the obtained electric signals and thus to determine the motion angular velocities. Moreover, the motion sensor arrays produced a short-circuit current density up to 10.71 mA/m(2), and an open-circuit voltage as high as 42.6 V with a remarkable signal-to-noise ratio up to 1000, which enables the devices as sensors to accurately record and transform the motions of the human joints, such as elbow, knee, heel, and even fingers, and thus renders it a superior and unique invention in the field of HMI.

Bi-Axial Solar Array Drive Mechanism: Design, Build and Environmental Testing

NASA Astrophysics Data System (ADS)

Phillips, Nigel; Ferris, Mark; Scheidegger, Noemy

2015-09-01

The development of the Bi-Axial Solar Array Drive Mechanism (BSADM) presented in this paper is a demonstration of SSTL’s innovation and pragmatic approach to spacecraft systems engineering and rapid development duration. The BSADM (Fig. 1) is designed to orient a solar array wing towards the sun, using its first rotation axis to track the sun, and its second rotation axis to compensate for the satellite orbit and attitude changes needed for a successful payload operation. The BSADM design approach - based on the use of heritage components where possible and focusing resource on key design requirements - led to the rapid design, manufacture and test of the new mechanism with a qualification model (flight representative proof mechanism), followed by the manufacture and test of a number of flight model BSADMs, all completed and delivered within 18 months to service the need of current and future SSTL missions. A job not only well done, but done efficiently - the SSTL way.

Shrink-induced single-cell plastic microwell array.

PubMed

Lew, Valerie; Nguyen, Diep; Khine, Michelle

2011-12-01

The ability to interrogate and track single cells over time in a high-throughput format would provide critical information for fundamental biological understanding of processes and for various applications, including drug screening and toxicology. We have developed an ultrarapid and simple method to create single-cell wells of controllable diameter and depth with commodity shrink-wrap film and tape. Using a programmable CO(2) laser, we cut hole arrays into the tape. The tape then serves as a shadow mask to selectively etch wells into commodity shrink-wrap film by O(2) plasma. When the shrink-wrap film retracts upon briefly heating, high-aspect plastic microwell arrays with diameters down to 20 μm are readily achieved. We calibrated the loading procedure with fluorescent microbeads. Finally, we demonstrate the utility of the wells by loading fluorescently labeled single human embryonic stem cells into the wells. Copyright © 2011 Society for Laboratory Automation and Screening. Published by Elsevier Inc. All rights reserved.

Simultaneous data communication and position sensing with an impact ionization engineered avalanche photodiode array for free space optical communication

NASA Astrophysics Data System (ADS)

Ferraro, Mike S.; Mahon, Rita; Rabinovich, William S.; Murphy, James L.; Dexter, James L.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian D.

2017-02-01

Photodetectors in free space optical communication systems perform two functions: reception of data communication signals and position sensing for pointing, tracking, and stabilization. Traditionally, the optical receive path in an FSO system is split into separate paths for data detection and position sensing. The need for separate paths is a consequence of conflicting performance criteria between position sensitive detectors (PSD) and data detectors. Combining the functionality of both detector types requires that the combinational sensor not only have the bandwidth to support high data rate communication but the active area and spatial discrimination to accommodate position sensing. In this paper we present a large area, concentric five element impact ionization engineered avalanche photodiode array rated for bandwidths beyond 1GHz with a measured carrier ionization ratio of less than 0.1 at moderate APD gains. The integration of this array as a combinational sensor in an FSO system is discussed along with the development of a pointing and stabilization algorithm.

Ka Band Objects: Observation and Monitoring (KaBOOM)

NASA Astrophysics Data System (ADS)

Geldzahler, B.

2012-09-01

NASA has embarked on a path that will enable the implementation of a high power, high resolution X/Ka band radar system using widely spaced 12m antennas to better track and characterize near Earth objects and orbital debris. This radar system also has applications for cost effective space situational awareness. We shall demonstrate Ka band coherent uplink arraying with real-time atmospheric compensation using three 12m antennas at the Kennedy Space Center (KSC). Our proposed radar system can complement and supplement the activities of the Space Fence. The proposed radar array has the advantages of filling the gap between dusk and dawn and offers the possibility of high range resolution (4 cm) and high spatial resolution (?10 cm at GEO) when used in a VLBI mode. KSC was chosen because [a] of reduced implementation costs, [b] there is a lot of water vapor in the air (not Ka band friendly), and [c] the test satellites have a low elevation adding more attenuation and turbulence to the demonstration. If Ka band coherent uplink arraying can be made to work at KSC, it will work anywhere. We expect to rebaseline X-band in 2013, and demonstrate Ka band uplink arraying in 2014.

Dedicated ultrasound speckle tracking to study tendon displacement

NASA Astrophysics Data System (ADS)

Korstanje, Jan-Wiebe H.; Selles, Ruud W.; Stam, Henk J.; Hovius, Steven E. R.; Bosch, Johan G.

2009-02-01

Ultrasound can be used to study tendon and muscle movement. However, quantization is mostly based on manual tracking of anatomical landmarks such as the musculotendinous junction, limiting the applicability to a small number of muscle-tendon units. The aim of this study is to quantify tendon displacement without employing anatomical landmarks, using dedicated speckle tracking in long B-mode image sequences. We devised a dedicated two-dimensional multikernel block-matching scheme with subpixel accuracy to handle large displacements over long sequences. Images were acquired with a Philips iE33 with a 7 MHz linear array and a VisualSonics Vevo 770 using a 40 MHz mechanical probe. We displaced the flexor digitorum superficialis of two pig cadaver forelegs with three different velocities (4,10 and 16 mm/s) over 3 distances (5, 10, 15 mm). As a reference, we manually determined the total displacement of an injected hyperechogenic bullet in the tendons. We automatically tracked tendon parts with and without markers and compared results to the true displacement. Using the iE33, mean tissue displacement underestimations for the three different velocities were 2.5 +/- 1.0%, 1.7 +/- 1.1% and 0.7 +/- 0.4%. Using the Vevo770, mean tissue displacement underestimations were 0.8 +/- 1.3%, 0.6 +/- 0.3% and 0.6 +/- 0.3%. Marker tracking displacement underestimations were only slightly smaller, showing limited tracking drift for non-marker tendon tissue as well as for markers. This study showed that our dedicated speckle tracking can quantify extensive tendon displacement with physiological velocities without anatomical landmarks with good accuracy for different types of ultrasound configurations. This technique allows tracking of a much larger range of muscle-tendon units than by using anatomical landmarks.