Practical guidelines for interpreting copy number gains detected by high-resolution array in routine diagnostics

PubMed Central

Hanemaaijer, Nicolien M; Sikkema-Raddatz, Birgit; van der Vries, Gerben; Dijkhuizen, Trijnie; Hordijk, Roel; van Essen, Anthonie J; Veenstra-Knol, Hermine E; Kerstjens-Frederikse, Wilhelmina S; Herkert, Johanna C; Gerkes, Erica H; Leegte, Lamberta K; Kok, Klaas; Sinke, Richard J; van Ravenswaaij-Arts, Conny M A

2012-01-01

The correct interpretation of copy number gains in patients with developmental delay and multiple congenital anomalies is hampered by the large number of copy number variations (CNVs) encountered in healthy individuals. The variable phenotype associated with copy number gains makes interpretation even more difficult. Literature shows that inheritence, size and presence in healthy individuals are commonly used to decide whether a certain copy number gain is pathogenic, but no general consensus has been established. We aimed to develop guidelines for interpreting gains detected by array analysis using array CGH data of 300 patients analysed with the 105K Agilent oligo array in a diagnostic setting. We evaluated the guidelines in a second, independent, cohort of 300 patients. In the first 300 patients 797 gains of four or more adjacent oligonucleotides were observed. Of these, 45.4% were de novo and 54.6% were familial. In total, 94.8% of all de novo gains and 87.1% of all familial gains were concluded to be benign CNVs. Clinically relevant gains ranged from 288 to 7912 kb in size, and were significantly larger than benign gains and gains of unknown clinical relevance (P<0.001). Our study showed that a threshold of 200 kb is acceptable in a clinical setting, whereas heritability does not exclude a pathogenic nature of a gain. Evaluation of the guidelines in the second cohort of 300 patients revealed that the interpretation guidelines were clear, easy to follow and efficient. PMID:21934709

Scale factor and noise performance tests of the Bendix Corporation Rate Gyro Assembly (RGA)

NASA Astrophysics Data System (ADS)

Kim, R.; Hoffman, J.

1980-08-01

Three Bendix Corporation gyroscopes in a Rate Gyro Assembly (RGA) were tested at the Central Inertial Guidance Test Facility (CIGTF), 6585th Test Group, Holloman Air Force Base, New Mexico, from 29 May through 19 June 1980, for the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center (MSFC), Huntsville, Alabama. The purpose of the tests was to characterize the noise performance of each gyro in the RGA in the frequency range of 0.01 hertz to 20 hertz. Gyro noise performance was then compared with seismic activity and previous results from Bendix Corporation testing. Eight-point tests were performed to obtain scale factors which were used to scale the Power Spectral Density (PSD) data. The PSD test series consisted of 1, 2.5, 5, 40 and 180 minute tests under various operating conditions (wheels on and off, low and high rate modes, and horizontal and vertical output axis orientations). The data are presented as PSD plots in the frequency domain. These results show a negligible seismic contribution and are comparable with data obtained at the Bendix test facility.

The Ustilago maydis a2 Mating-Type Locus Genes lga2 and rga2 Compromise Pathogenicity in the Absence of the Mitochondrial p32 Family Protein Mrb1

PubMed Central

Bortfeld, Miriam; Auffarth, Kathrin; Kahmann, Regine; Basse, Christoph W.

2004-01-01

The Ustilago maydis mrb1 gene specifies a mitochondrial matrix protein with significant similarity to mitochondrial p32 family proteins known from human and many other eukaryotic species. Compatible mrb1 mutant strains were able to mate and form dikaryotic hyphae; however, proliferation within infected tissue and the ability to induce tumor development of infected maize (Zea mays) plants were drastically impaired. Surprisingly, manifestation of the mrb1 mutant phenotype selectively depended on the a2 mating type locus. The a2 locus contains, in addition to pheromone signaling components, the genes lga2 and rga2 of unknown function. Deletion of lga2 in an a2Δmrb1 strain fully restored pathogenicity, whereas pathogenicity was partially regained in an a2Δmrb1Δrga2 strain, implicating a concerted action between Lga2 and Rga2 in compromising pathogenicity in Δmrb1 strains. Lga2 and Rga2 localized to mitochondria and Mrb1 interacted with Rga2 in the yeast two-hybrid system. Conditional expression of lga2 in haploid cells reduced vegetative growth, conferred mitochondrial fragmentation and mitochondrial DNA degradation, and interfered with respiratory activity. The consequences of lga2 overexpression depended on the expression strength and were greatly exacerbated in Δmrb1 mutants. We propose that Lga2 interferes with mitochondrial fusion and that Mrb1 controls this activity, emphasizing a critical link between mitochondrial morphology and pathogenicity. PMID:15273296

Determination of the conversion gain and the accuracy of its measurement for detector elements and arrays

NASA Astrophysics Data System (ADS)

Beecken, B. P.; Fossum, E. R.

1996-07-01

Standard statistical theory is used to calculate how the accuracy of a conversion-gain measurement depends on the number of samples. During the development of a theoretical basis for this calculation, a model is developed that predicts how the noise levels from different elements of an ideal detector array are distributed. The model can also be used to determine what dependence the accuracy of measured noise has on the size of the sample. These features have been confirmed by experiment, thus enhancing the credibility of the method for calculating the uncertainty of a measured conversion gain. detector-array uniformity, charge coupled device, active pixel sensor.

Gain monitoring of telescope array photomultiplier cameras for the first 4 years of operation

NASA Astrophysics Data System (ADS)

Shin, B. K.; Tokuno, H.; Tsunesada, Y.; Abu-Zayyad, T.; Aida, R.; Allen, M.; Anderson, R.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, E. J.; Cho, W. R.; Fujii, H.; Fujii, T.; Fukuda, T.; Fukushima, M.; Hanlon, W.; Hayashi, K.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Hiyama, K.; Honda, K.; Iguchi, T.; Ikeda, D.; Ikuta, K.; Inoue, N.; Ishii, T.; Ishimori, R.; Ivanov, D.; Iwamoto, S.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kanbe, T.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kido, E.; Kim, H. B.; Kim, H. K.; Kim, J. H.; Kim, J. H.; Kitamoto, K.; Kitamura, S.; Kitamura, Y.; Kobayashi, K.; Kobayashi, Y.; Kondo, Y.; Kuramoto, K.; Kuzmin, V.; Kwon, Y. J.; Lim, S. I.; Machida, S.; Martens, K.; Martineau, J.; Matsuda, T.; Matsuura, T.; Matsuyama, T.; Matthews, J. N.; Myers, I.; Minamino, M.; Miyata, K.; Murano, Y.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nam, S. W.; Nonaka, T.; Ogio, S.; Ohnishi, M.; Ohoka, H.; Oki, K.; Oku, D.; Okuda, T.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Roh, S. Y.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Sampson, A. L.; Scott, L. M.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, J. I.; Shirahama, T.; Smith, J. D.; Sokolsky, P.; Sonley, T. J.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T.; Suzuki, S.; Takahashi, Y.; Takeda, M.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tomida, T.; Troitsky, S.; Tsutsumi, K.; Tsuyuguchi, Y.; Uchihori, Y.; Udo, S.; Ukai, H.; Vasiloff, G.; Wada, Y.; Wong, T.; Wood, M.; Yamakawa, Y.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zhou, X.; Zollinger, R.; Zundel, Z.

2014-12-01

The stability of the gain of the photomultiplier (PMT) camera for the Fluorescence Detector (FD) of the Telescope Array experiment was monitored using an 241Am loaded scintillator pulsers (YAP) and a diffused xenon flasher (TXF) for a selected set of 35 PMT-readout channels. From the monitoring of YAP pulses over four years of FD operation, we found slow monotonic drifts of PMT gains at a rate of -1.7 +1.7%/year. An average of the PMT gains over the 35 channels stayed nearly constant with a rate of change measured at -0.01±0.31(stat)±0.21(sys)%/year. No systematic decrease of the PMT gain caused by the night sky background was observed. Monitoring by the TXF also tracked the PMT gain drift of the YAP at 0.88±0.14(stat)%/year.

Maximization of the directivity ratio with the desired audible gain level for broadband design of near field loudspeaker arrays

NASA Astrophysics Data System (ADS)

Kim, Daesung; Kim, Kihyun; Wang, Semyung; Lee, Sung Q.; Crocker, Malcolm J.

2011-11-01

This paper mainly addresses design methods for near field loudspeaker arrays. These methods have been studied recently since they can be used to realize a personal audio space without the use of headphones. From a practical view point, they can also be used to form a directional sound beam within a short distance from the sources especially using a linear loudspeaker array. In this regard, we re-analyzed the previous near field beamforming methods in order to obtain a comprehensive near field beamforming formulation. Broadband directivity control is proposed for multi-objective optimization, which maximizes the directivity with the desired gain, where both the directivity and the gain are commonly used array performance measures. This method of control aims to form a directive sound beam within a short distance while widening the frequency range of the beamforming. Simulation and experimental results demonstrate that broadband directivity control achieves higher directivity and gain over our whole frequency range of interest compared with previous beamforming methods.

Gain assisted coherent control of microwave pulse in a one dimensional array of artificial atoms

NASA Astrophysics Data System (ADS)

Waqas, Mohsin; Ayaz, M. Q.; Waseem, M.; Qamar, Sajid; Qamar, Shahid

2018-06-01

We study the coherent propagation of a microwave pulse through a one-dimensional array of artificial atoms. The scheme is based upon gain assisted propagation of the pulse using two-photon Raman transition in a three-level superconducting artificial atoms (SAAs) coupled to a microwave transmission line. Our results show that the group velocity can be significantly reduced by increasing the Rabi frequency of the pump fields which in turn can lead to an efficient storage of the pulse inside a 1D array of SAAs. Further, the intensity of the transmitted pulse increases with the number of artificial atoms owing to the gain associated with the two-photon Raman transition. Our results also show that the window width decreases for both scattering and negligible scattering cases with the increase in the number of SAAs. The fidelity of the system also remains high even after the passage of the pulse through a large number of SAAs.

Charge Gain, Voltage Gain, and Node Capacitance of the SAPHIRA Detector Pixel by Pixel

NASA Astrophysics Data System (ADS)

Pastrana, Izabella M.; Hall, Donald N. B.; Baker, Ian M.; Jacobson, Shane M.; Goebel, Sean B.

2018-01-01

The University of Hawai`i Institute for Astronomy has partnered with Leonardo (formerly Selex) in the development of HgCdTe linear mode avalanche photodiode (L-APD) SAPHIRA detectors. The SAPHIRA (Selex Avalanche Photodiode High-speed Infra-Red Array) is ideally suited for photon-starved astronomical observations, particularly near infrared (NIR) adaptive optics (AO) wave-front sensing. I have measured the stability, and linearity with current, of a 1.7-um (10% spectral bandpass) infrared light emitting diode (IR LED) used to illuminate the SAPHIRA and have then utilized this source to determine the charge gain (in e-/ADU), voltage gain (in uV/ADU), and node capacitance (in fF) for each pixel of the 320x256@24um SAPHIRA. These have previously only been averages over some sub-array. Determined from the ratio of the temporal averaged signal level to variance under constant 1.7-um LED illumination, I present the charge gain pixel-by-pixel in a 64x64 sub-array at the center of the active area of the SAPHIRA (analyzed separately as four 32x32 sub-arrays) to be about 1.6 e-/ADU (σ=0.5 e-/ADU). Additionally, the standard technique of varying the pixel reset voltage (PRV) in 10 mV increments and recording output frames for the same 64x64 subarray found the voltage gain per pixel to be about 11.7 uV/ADU (σ=0.2 uV/ADU). Finally, node capacitance was found to be approximately 23 fF (σ=6 fF) utilizing the aforementioned charge and voltage gain measurements. I further discuss the linearity measurements of the 1.7-um LED used in the charge gain characterization procedure.

Microchannel plate fabrication using glass capillary arrays with Atomic Layer Deposition films for resistance and gain

NASA Astrophysics Data System (ADS)

Popecki, M. A.; Adams, B.; Craven, C. A.; Cremer, T.; Foley, M. R.; Lyashenko, A.; O'Mahony, A.; Minot, M. J.; Aviles, M.; Bond, J. L.; Stochaj, M. E.; Worstell, W.; Elam, J. W.; Mane, A. U.; Siegmund, O. H. W.; Ertley, C.; Kistler, L. M.; Granoff, M. S.

2016-08-01

Microchannel plates (MCPs) have been used for many years in space flight instrumentation as fast, lightweight electron multipliers. A new MCP fabrication method combines a glass substrate composed of hollow glass capillary arrays with thin film coatings to provide the resistive and secondary electron emissive properties. Using this technique, the gain, resistance, and glass properties may be chosen independently. Large-area MCPs are available at moderate cost. Secondary emission films of Al2O3 and MgO provide sustained high gain as charge is extracted from the MCP. Long lifetimes are possible, and a total extracted charge of 7 C/cm2 has been demonstrated. Background rates are low because the glass substrate has little radioactive potassium 40. Curved MCPs are easily fabricated with this technique to suit instrument symmetries, simplifying secondary electron steering and smoothing azimuthal efficiency.

Generation of Hermite-Gaussian modes and vortex arrays based on two-dimensional gain distribution controlled microchip laser.

PubMed

Kong, Weipeng; Sugita, Atsushi; Taira, Takunori

2012-07-01

We have demonstrated high-order Hermite-Gaussian (HG) mode generation based on 2D gain distribution control edge-pumped, composite all-ceramic Yb:YAG/YAG microchip lasers using a V-type cavity. Several hundred milliwatts to several watts HG(mn) modes are achieved. We also generated different kinds of vortex arrays directly from the oscillator with the same power level. In addition, a more than 7 W doughnut-shape mode can be generated in the same cavity.

Highly Directive Array Aperture

DTIC Science & Technology

2013-02-13

generally to sonar arrays with acoustic discontinuities, and, more particularly, to increasing the directivity gain of a sonar array aperture by...sought by sonar designers. [0005] The following patents and publication show various types of acoustic arrays with coatings and discontinuities that...discloses a sonar array uses multiple acoustically transparent layers. One layer is a linear array of acoustic sensors that is substantially

Prediction of antenna array performance from subarray measurements

NASA Technical Reports Server (NTRS)

Huisjen, M. A.

1978-01-01

Computer runs were used to determine the effect of mechanical distortions on array pattern performance. Subarray gain data, along with feed network insertion loss, and insertion phase data were combined with the analysis of Ruze on random errors to predict gain of a full array.

Amplitude steered array

NASA Technical Reports Server (NTRS)

Dietrich, F. J.; Koloboff, G. J.; Martel, R. J.; Johnson, C. C. (Inventor)

1974-01-01

A spin stabilized satellite has an electronically despun antenna array comprising a multiplicity of peripheral antenna elements. A high gain energy beam is established by connecting a suitable fraction or array of the elements in phase. The beam is steered or caused to scan by switching elements in sequence into one end of the array as elements at the other end of the array are switched out. The switching transients normally associated with such steering are avoided by an amplitude control system. Instead of abruptly switching from one element to the next, a fixed value of power is gradually transferred from the element at the trailing edge of the array to the element next to the leading edge.

Graphene array antenna for 5G applications

NASA Astrophysics Data System (ADS)

Sa'don, Siti Nor Hafizah; Kamarudin, Muhammad Ramlee; Ahmad, Fauzan; Jusoh, Muzammil; Majid, Huda A.

2017-02-01

Fifth generation (5G) needs to provide better coverage than the previous generation. However, high frequency and millimeter wave experience penetration loss, propagation loss and even more loss in energy for long distance. Hence, a graphene array antenna is proposed for high gain to cover a long distance communications since array antenna enables in providing more directive beams. The investigation is conducted on three types of substrates with gain achieved is more than 7 dBi. The gain obtained is good since it is comparable with other studies. In addition, these antennas consume small numbers of elements to achieve high gain.

Gain Shift Corrections at Chi-Nu

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

Brown, Tristan Brooks; Devlin, Matthew James

Ambient conditions have the potential to cause changes in liquid scintillator detector gain that vary with time and temperature. These gain shifts can lead to poor resolution in both energy as well as pulse shape discrimination. In order to correct for these shifts in the Chi-Nu high energy array, a laser system has been developed for calibration of the pulse height signals.

EPOXI Uplink Array Experiment of June 27, 2008

NASA Astrophysics Data System (ADS)

Vilnrotter, V.; Tsao, P. C.; Lee, D. K.; Cornish, T. P.; Paal, L.; Jamnejad, V.

2008-08-01

Uplink array technology is currently being developed for NASA's Deep Space Network (DSN) to provide greater range and data throughput for future NASA missions, including manned missions to Mars and exploratory missions to the outer planets, the Kuiper Belt, and beyond. The DSN uplink arrays employ N microwave antennas transmitting at 7.2 GHz (X-band) to produce signals that add coherently at the spacecraft, hence providing a power gain of N^2 over a single antenna. This gain can be traded off directly for an N^2 higher data rate at a given distance such as Mars, providing, for example, high-definition video broadcast from Earth to a future human mission, or it can provide a given data rate for commands and software uploads at a distance N times greater than would be possible with a single antenna. The uplink arraying concept has been recently demonstrated using the three operational 34-m antennas of the Apollo Complex at the Goldstone Deep Space Communications Complex in California, which transmitted arrayed signals to the EPOXI spacecraft (an acronym formed from EPOCh and DIXI: Extrasolar Planetary Observation and Characterization and Deep Impact Extended Investigation). Both two-element and three-element uplink arrays were configured, and the theoretical array gains of 6 dB and 9.5 dB, respectively, were demonstrated experimentally. This required initial phasing of the array elements, the generation of accurate frequency predicts to maintain phase from each antenna despite relative velocity components due to Earth rotation and spacecraft trajectory, and monitoring of the ground-system phase for possible drifts caused by thermal effects over the 16-km fiber-optic signal distribution network. This article provides a description of the equipment and techniques used to demonstrate the uplink arraying concept in a relevant operational environment. Data collected from the EPOXI spacecraft are also analyzed to verify array calibration, array gain, and system stability

A hybrid intelligent controller for a twin rotor MIMO system and its hardware implementation.

PubMed

Juang, Jih-Gau; Liu, Wen-Kai; Lin, Ren-Wei

2011-10-01

This paper presents a fuzzy PID control scheme with a real-valued genetic algorithm (RGA) to a setpoint control problem. The objective of this paper is to control a twin rotor MIMO system (TRMS) to move quickly and accurately to the desired attitudes, both the pitch angle and the azimuth angle in a cross-coupled condition. A fuzzy compensator is applied to the PID controller. The proposed control structure includes four PID controllers with independent inputs in 2-DOF. In order to reduce total error and control energy, all parameters of the controller are obtained by a RGA with the system performance index as a fitness function. The system performance index utilized the integral of time multiplied by the square error criterion (ITSE) to build a suitable fitness function in the RGA. A new method for RGA to solve more than 10 parameters in the control scheme is investigated. For real-time control, Xilinx Spartan II SP200 FPGA (Field Programmable Gate Array) is employed to construct a hardware-in-the-loop system through writing VHDL on this FPGA. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Improved Grid-Array Millimeter-Wave Amplifier

NASA Technical Reports Server (NTRS)

Rosenberg, James J.; Rutledge, David B.; Smith, R. Peter; Weikle, Robert

1993-01-01

Improved grid-array amplifiers operating at millimeter and submillimeter wavelengths developed for use in communications and radar. Feedback suppressed by making input polarizations orthogonal to output polarizations. Amplifier made to oscillate by introducing some feedback. Several grid-array amplifiers concatenated to form high-gain beam-amplifying unit.

Integrated residential photovoltaic array development

NASA Astrophysics Data System (ADS)

Shepard, N. F., Jr.

1981-12-01

An advanced, universally-mountable, integrated residential photovoltaic array concept was defined based upon an in-depth formulation and evaluation of three candidate approaches which were synthesized from existing or proposed residential array concepts. The impact of module circuitry and process sequence is considered and technology gaps and performance drivers associated with residential photovoltaic array concepts are identified. The actual learning experience gained from the comparison of the problem areas of the hexagonal shingle design with the rectangular module design led to what is considered an advanced array concept. Building the laboratory mockup provided actual experience and the opportunity to uncover additional technology gaps.

Integrated residential photovoltaic array development

NASA Technical Reports Server (NTRS)

Shepard, N. F., Jr.

1981-01-01

An advanced, universally-mountable, integrated residential photovoltaic array concept was defined based upon an in-depth formulation and evaluation of three candidate approaches which were synthesized from existing or proposed residential array concepts. The impact of module circuitry and process sequence is considered and technology gaps and performance drivers associated with residential photovoltaic array concepts are identified. The actual learning experience gained from the comparison of the problem areas of the hexagonal shingle design with the rectangular module design led to what is considered an advanced array concept. Building the laboratory mockup provided actual experience and the opportunity to uncover additional technology gaps.

Reflection Grating Array Associated with the Reflection Grating Spectrometer Developed by the Space Research Organization of the Netherlands for the X-ray Multi-Mirror Mission (XMM)

NASA Technical Reports Server (NTRS)

Kahn, Steven M.

2001-01-01

The University of California, Berkeley (UCB) served as the Principal Investigator institution for the United States participation in the development of the Reflection Grating Spectrometer (RGS) which included the design, development, fabrication, and testing of the Reflection Grating Assembly (RGA). UCB was assisted in this role by the Lawrence Livermore National Laboratory and Columbia University who provided the primary facilities, materials, services and personnel necessary to complete the development. UC Berkeley's Dr. Steven Kahn provided the technical and scientific oversight for the design. development and testing of the RGA units by monitoring the performance of the units at various stages in their development. Dr. Kahn was also the primary contact with the Space Research Organization of the Netherlands (SRON) and represented the RGA development at all SRON and European Space Agency (ESA) reviews of the RGA status. In accordance with the contract, the team designed and developed novel optical technology to meet the unique requirements of the RGS. The ESA XMM-Newton Mission carries two identical Reflection Grating Spectrometers (RGS) behind two of its three nested sets of Wolter I type mirrors. The instrument allows high-resolution measurements in the soft X-ray range (6 to 38 angstroms or 2.1 to 0.3 keV) with a maximum effective area of about 140 sq cm at 15 angstroms. Its design is optimized for the detection of the K-shell transitions of carbon, nitrogen, oxygen, neon, magnesium, and silicon. as well as the L shell transitions of iron. The RGA itself consists of two units. A structure for each unit was designed to hold up to 220 gratings. In its final configuration, one unit holds 182 gratings and the second hold 181 gratings.

Automatic Parallelization of Numerical Python Applications using the Global Arrays Toolkit

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

Daily, Jeffrey A.; Lewis, Robert R.

2011-11-30

Global Arrays is a software system from Pacific Northwest National Laboratory that enables an efficient, portable, and parallel shared-memory programming interface to manipulate distributed dense arrays. The NumPy module is the de facto standard for numerical calculation in the Python programming language, a language whose use is growing rapidly in the scientific and engineering communities. NumPy provides a powerful N-dimensional array class as well as other scientific computing capabilities. However, like the majority of the core Python modules, NumPy is inherently serial. Using a combination of Global Arrays and NumPy, we have reimplemented NumPy as a distributed drop-in replacement calledmore » Global Arrays in NumPy (GAiN). Serial NumPy applications can become parallel, scalable GAiN applications with only minor source code changes. Scalability studies of several different GAiN applications will be presented showing the utility of developing serial NumPy codes which can later run on more capable clusters or supercomputers.« less

Spatial-Gain Improvement Resulting from Left/Right Discriminating Elements of an Underwater Towed Array

DTIC Science & Technology

1981-09-15

DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY rsil RONALD A. WAGSTAFF and PIETRO MANASCA D TIC": L• ’" .... 4"•’.,, 15 SEPTEMBER 1981...IMPROVEMENT RESULTING FROM LEFT/RIGHT DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY by Ronald A. Wagstaff and Pietro Zanasca 15 September 1981 F...RESULTING FROM LEFT/RIGHT DISCRIMINATING ELEMENTS OF AN UNDERWATER TOWED ARRAY by Ronald A. Wagstaff and Pietro Zanasca ABSTRACT The improvement in

Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

NASA Technical Reports Server (NTRS)

Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

2013-01-01

Polyimide aerogels were considered to serve as a filling for millimeter-wave waveguides. While these waveguides present a slightly higher loss than hollow waveguides, they have less losses than Duroid substrate integrated waveguides (less than 0.15 dB at Ka-band, in a 20 mm section), and exhibit an order of magnitude of mass reduction when compared to commercial waveguides. A Ka-band slotted aerogel-filled-waveguide array was designed, which provided the same gain (9 dBi) as its standard waveguide counterpart, and a slotted aerogel-filled-waveguide array using folded-slots was designed for comparison, obtaining a gain of 9 dB and a bandwidth of 590 MHz.

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.

S-band antenna phased array communications system

NASA Technical Reports Server (NTRS)

Delzer, D. R.; Chapman, J. E.; Griffin, R. A.

1975-01-01

The development of an S-band antenna phased array for spacecraft to spacecraft communication is discussed. The system requirements, antenna array subsystem design, and hardware implementation are examined. It is stated that the phased array approach offers the greatest simplicity and lowest cost. The objectives of the development contract are defined as: (1) design of a medium gain active phased array S-band communications antenna, (2) development and test of a model of a seven element planar array of radiating elements mounted in the appropriate cavity matrix, and (3) development and test of a breadboard transmit/receive microelectronics module.

Phased Antenna Array for Global Navigation Satellite System Signals

NASA Technical Reports Server (NTRS)

Turbiner, Dmitry (Inventor)

2015-01-01

Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.

Gibberellin Induces Diploid Pollen Formation by Interfering with Meiotic Cytokinesis1[OPEN

PubMed Central

De Storme, Nico

2017-01-01

The plant hormone gibberellic acid (GA) controls many physiological processes, including cell differentiation, cell elongation, seed germination, and response to abiotic stress. In this study, we report that exogenous treatment of flowering Arabidopsis (Arabidopsis thaliana) plants with GA specifically affects the process of male meiotic cytokinesis leading to meiotic restitution and the production of diploid (2n) pollen grains. Similar defects in meiotic cell division and reproductive ploidy stability occur in Arabidopsis plants depleted of RGA and GAI, two members of the DELLA family that function as suppressor of GA signaling. Cytological analysis of the double rga-24 gai-t6 mutant revealed that defects in male meiotic cytokinesis are not caused by alterations in meiosis I (MI or meiosis II (MII) chromosome dynamics, but instead result from aberrations in the spatial organization of the phragmoplast-like radial microtubule arrays (RMAs) at the end of meiosis II. In line with a role for GA in the genetic regulation of the male reproductive system, we additionally show that DELLA downstream targets MYB33 and MYB65 are redundantly required for functional RMA biosynthesis and male meiotic cytokinesis. By analyzing the expression of pRGA::GFP-RGA in the wild-type Landsberg erecta background, we demonstrate that the GFP-RGA protein is specifically expressed in the anther cell layers surrounding the meiocytes and microspores, suggesting that appropriate GA signaling in the somatic anther tissue is critical for male meiotic cell wall formation and thus plays an important role in consolidating the male gametophytic ploidy consistency. PMID:27621423

Study of array plasma antenna parameters

NASA Astrophysics Data System (ADS)

Kumar, Rajneesh; Kumar, Prince

2018-04-01

This paper is aimed to investigate the array plasma antenna parameters to help the optimization of an array plasma antenna. Single plasma antenna is transformed into array plasma antenna by changing the operating parameters. The re-configurability arises in the form of striations, due to transverse bifurcation of plasma column by changing the operating parameters. Each striation can be treated as an antenna element and system performs like an array plasma antenna. In order to achieve the goal of this paper, three different configurations of array plasma antenna (namely Array 1, Array 2 and Array 3) are simulated. The observations are made on variation in antenna parameters like resonance frequency, radiation pattern, directivity and gain with variation in length and number of antenna elements for each array plasma antenna. Moreover experiments are also performed and results are compared with simulation. Further array plasma antenna parameters are also compared with monopole plasma antenna parameters. The study of present paper invoke the array plasma antenna can be applied for steering and controlling the strength of Wi-Fi signals as per requirement.

Application of MEMS Microphone Array Technology to Airframe Noise Measurements

NASA Technical Reports Server (NTRS)

Humphreys, William M., Jr.; Shams, Qamar A.; Graves, Sharon S.; Sealey, Bradley S.; Bartram, Scott M.; Comeaux, Toby

2005-01-01

Current generation microphone directional array instrumentation is capable of extracting accurate noise source location and directivity data on a variety of aircraft components, resulting in significant gains in test productivity. However, with this gain in productivity has come the desire to install larger and more complex arrays in a variety of ground test facilities, creating new challenges for the designers of array systems. To overcome these challenges, a research study was initiated to identify and develop hardware and fabrication technologies which could be used to construct an array system exhibiting acceptable measurement performance but at much lower cost and with much simpler installation requirements. This paper describes an effort to fabricate a 128-sensor array using commercially available Micro-Electro-Mechanical System (MEMS) microphones. The MEMS array was used to acquire noise data for an isolated 26%-scale high-fidelity Boeing 777 landing gear in the Virginia Polytechnic Institute and State University Stability Tunnel across a range of Mach numbers. The overall performance of the array was excellent, and major noise sources were successfully identified from the measurements.

Optical transfer function of Starlette retroreflector array

NASA Technical Reports Server (NTRS)

Arnold, D. A.

1975-01-01

An optical transfer function was computed for the retroreflector array carried by the Starlette satellite (1975 10A). The range correction is given for extrapolating laser range measurements to the center of mass of the satellite. The gain function and active reflecting area of the array are computed for estimating laser-echo signal strengths.

Adaptive Sparse Representation for Source Localization with Gain/Phase Errors

PubMed Central

Sun, Ke; Liu, Yimin; Meng, Huadong; Wang, Xiqin

2011-01-01

Sparse representation (SR) algorithms can be implemented for high-resolution direction of arrival (DOA) estimation. Additionally, SR can effectively separate the coherent signal sources because the spectrum estimation is based on the optimization technique, such as the L1 norm minimization, but not on subspace orthogonality. However, in the actual source localization scenario, an unknown gain/phase error between the array sensors is inevitable. Due to this nonideal factor, the predefined overcomplete basis mismatches the actual array manifold so that the estimation performance is degraded in SR. In this paper, an adaptive SR algorithm is proposed to improve the robustness with respect to the gain/phase error, where the overcomplete basis is dynamically adjusted using multiple snapshots and the sparse solution is adaptively acquired to match with the actual scenario. The simulation results demonstrate the estimation robustness to the gain/phase error using the proposed method. PMID:22163875

All-dielectric rod antenna array for terahertz communications

NASA Astrophysics Data System (ADS)

Withayachumnankul, Withawat; Yamada, Ryoumei; Fujita, Masayuki; Nagatsuma, Tadao

2018-05-01

The terahertz band holds a potential for point-to-point short-range wireless communications at sub-terabit speed. To realize this potential, supporting antennas must have a wide bandwidth to sustain high data rate and must have high gain and low dissipation to compensate for the free space path loss that scales quadratically with frequency. Here we propose an all-dielectric rod antenna array with high radiation efficiency, high gain, and wide bandwidth. The proposed array is integral to a low-loss photonic crystal waveguide platform, and intrinsic silicon is the only constituent material for both the antenna and the feed to maintain the simplicity, compactness, and efficiency. Effective medium theory plays a key role in the antenna performance and integrability. An experimental validation with continuous-wave terahertz electronic systems confirms the minimum gain of 20 dBi across 315-390 GHz. A demonstration shows that a pair of such identical rod array antennas can handle bit-error-free transmission at the speed up to 10 Gbit/s. Further development of this antenna will build critical components for future terahertz communication systems.

Optical transfer function of NTS-1 retroreflector array

NASA Technical Reports Server (NTRS)

Arnold, D. A.

1974-01-01

An optical transfer function was computed for the retroreflector array carried by the NTS-1 satellite. Range corrections are presented for extrapolating laser range measurements to the center of mass of the satellite. The gain function of the array was computed for use in estimating laser-echo signal strengths.

Gimbals Drive and Control Electronics Design, Development and Testing of the LRO High Gain Antenna and Solar Array Systems

NASA Technical Reports Server (NTRS)

Chernyakov, Boris; Thakore, Kamal

2010-01-01

Launched June 18, 2009 on an Atlas V rocket, NASA's Lunar Reconnaissance Orbiter (LRO) is the first step in NASA's Vision for Space Exploration program and for a human return to the Moon. The spacecraft (SC) carries a wide variety of scientific instruments and provides an extraordinary opportunity to study the lunar landscape at resolutions and over time scales never achieved before. The spacecraft systems are designed to enable achievement of LRO's mission requirements. To that end, LRO's mechanical system employed two two-axis gimbal assemblies used to drive the deployment and articulation of the Solar Array System (SAS) and the High Gain Antenna System (HGAS). This paper describes the design, development, integration, and testing of Gimbal Control Electronics (GCE) and Actuators for both the HGAS and SAS systems, as well as flight testing during the on-orbit commissioning phase and lessons learned.

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.

Recurrence, submicroscopic complexity, and potential clinical relevance of copy gains detected by array CGH that are shown to be unbalanced insertions by FISH.

PubMed

Neill, Nicholas J; Ballif, Blake C; Lamb, Allen N; Parikh, Sumit; Ravnan, J Britt; Schultz, Roger A; Torchia, Beth S; Rosenfeld, Jill A; Shaffer, Lisa G

2011-04-01

Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 71 cases with unbalanced insertions identified using array CGH and FISH in 4909 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests that the phenotypic consequences may be benign. Cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification, and array CGH, we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion.

The 20 GHz circularly polarized, high temperature superconducting microstrip antenna array

NASA Technical Reports Server (NTRS)

Morrow, Jarrett D.; Williams, Jeffery T.; Long, Stuart A.; Wolfe, John C.

1994-01-01

The primary goal was to design and characterize a four-element, 20 GHz, circularly polarized microstrip patch antenna fabricated from YBa2Cu3O(x) superconductor. The purpose is to support a high temperature superconductivity flight communications experiment between the space shuttle orbiter and the ACTS satellite. This study is intended to provide information into the design, construction, and feasibility of a circularly polarized superconducting 20 GHz downlink or cross-link antenna. We have demonstrated that significant gain improvements can be realized by using superconducting materials for large corporate fed array antennas. In addition, we have shown that when constructed from superconducting materials, the efficiency, and therefore the gain, of microstrip patches increases if the substrate is not so thick that the dominant loss mechanism for the patch is radiation into the surface waves of the conductor-backed substrate. We have considered two design configurations for a superconducting 20 GHz four-element circularly polarized microstrip antenna array. The first is the Huang array that uses properly oriented and phased linearly polarized microstrip patch elements to realize a circularly polarized pattern. The second is a gap-coupled array of circularly polarized elements. In this study we determined that although the Huang array operates well on low dielectric constant substrates, its performance becomes extremely sensitive to mismatches, interelement coupling, and design imperfections for substrates with high dielectric constants. For the gap-coupled microstrip array, we were able to fabricate and test circularly polarized elements and four-element arrays on LaAlO3 using sputtered copper films. These antennas were found to perform well, with relatively good circular polarization. In addition, we realized a four-element YBa2Cu3O(x) array of the same design and measured its pattern and gain relative to a room temperature copper array. The patterns were

A 1-MHz 2-D CMUT array for HIFU thermal ablation

NASA Astrophysics Data System (ADS)

Yoon, Hyo-Seon; Vaithilingam, Srikant; Park, Kwan Kyu; Nikoozadeh, Amin; Firouzi, Kamyar; Choe, Jung Woo; Watkins, Ronald D.; Oguz, Huseyin Kagan; Kupnik, Mario; Pauly, Kim Butts; Khuri-Yakub, Pierre

2017-03-01

We developed a fully-populated 2-D capacitive micromachined ultrasonic transducer (CMUT) array for high intensity focused ultrasound (HIFU) treatment. The 2-D CMUT array, which consists of 20 × 20 square CMUT elements with an element-to-element pitch of 1 mm, was designed and fabricated using the thick-buried-oxide (BOX) fabrication process. It was then assembled on a custom interface board that can provide various array configurations depending on the desired applications. In this study, the interface board groups the CMUT array elements into eight channels, based on the phase delay from the element to the targeted focal point at a 20-mm distance from the array surface, which corresponds to an F-number of 1. An 8-channel phase generating system supplies continuous waves with eight different phases to the eight channels of the CMUT array through bias-tees and amplifiers. This array aperture, grouped into eight channels, gives a focusing gain of 6.09 according to field simulation using Field II. Assuming a peak-to-peak pressure of 1 MPa at the surface of the array, our custom temperature simulator predicts successful tissue ablation at the focus. During the measurements, each channel was tuned with a series inductor for an operational frequency of 1 MHz. With a CMUT DC bias of 100 V and a 1-MHz AC input voltage of 55 V, we achieved peak-to-peak output pressures of 173.9 kPa and 568.7 kPa at the array surface and at the focus, respectively. The focusing gain calculated from this measurement is 3.27, which is lower than the simulated gain of 6.09 because of the mutual radiation impedance among the CMUT cells. Further optimization of the operating condition of this array and design improvements for reducing the effect of mutual radiation impedance are currently on-going.

Two stage dual gate MESFET monolithic gain control amplifier for Ka-band

NASA Technical Reports Server (NTRS)

Sokolov, V.; Geddes, J.; Contolatis, A.

1987-01-01

A monolithic two stage gain control amplifier has been developed using submicron gate length dual gate MESFETs fabricated on ion implanted material. The amplifier has a gain of 12 dB at 30 GHz with a gain control range of over 30 dB. This ion implanted monolithic IC is readily integrable with other phased array receiver functions such as low noise amplifiers and phase shifters.

Phase-locked laser array

NASA Technical Reports Server (NTRS)

Botez, Dan (Inventor)

1987-01-01

A phase-locked laser array comprises a body of semiconductor material having means for defining a plurality of substantially parallel lasing zones which are spaced an effective distance apart so that the modes of the adjacent lasing zones are phase-locked to one another. One of the array electrodes comprises a plurality of electrical contacts to the body between the lasing zones. These contacts provide an enhanced current density profile and thus an increase in the gain in the regions between the lasing zones so that zero degree phase-shift operation between adjacent lasing zones is achievable.

Development of components for an S-band phased array antenna subsystem

NASA Technical Reports Server (NTRS)

1975-01-01

The system requirements, module test data, and S-band phased array subsystem test data are discussed. Of the two approaches to achieving antenna gain (mechanically steered reflector or electronically steered phased array), the phased array approach offers the greatest simplicity and lowest cost (size, weight, power, and dollars) for this medium gain. A competitive system design is described as well as hardware evaluation which will lead to timely availability of this technology for implementing such a system. The objectives of the study were: to fabricate and test six engineering model transmit/receive microelectronics modules; to design, fabricate, and test one dc and logic multilayer manifold; and to integrate and test an S-band phased array antenna subsystem composed of antenna elements, seven T/R modules, RF manifolds and dc manifold.

Hydrogen Epoch of Reinozation Array (HERA) Calibrated FFT Correlator Simulation

NASA Astrophysics Data System (ADS)

Salazar, Jeffrey David; Parsons, Aaron

2018-01-01

The Hydrogen Epoch of Reionization Array (HERA) project is an astronomical radio interferometer array with a redundant baseline configuration. Interferometer arrays are being used widely in radio astronomy because they have a variety of advantages over single antenna systems. For example, they produce images (visibilities) closely matching that of a large antenna (such as the Arecibo observatory), while both the hardware and maintenance costs are significantly lower. However, this method has some complications; one being the computational cost of correlating data from all of the antennas. A correlator is an electronic device that cross-correlates the data between the individual antennas; these are what radio astronomers call visibilities. HERA, being in its early stages, utilizes a traditional correlator system. The correlator cost scales as N2, where N is the number of antennas in the array. The purpose of a redundant baseline configuration array setup is for the use of a more efficient Fast Fourier Transform (FFT) correlator. FFT correlators scale as Nlog2N. The data acquired from this sort of setup, however, inherits geometric delay and uncalibrated antenna gains. This particular project simulates the process of calibrating signals from astronomical sources. Each signal “received” by an antenna in the simulation is given random antenna gain and geometric delay. The “linsolve” Python module was used to solve for the unknown variables in the simulation (complex gains and delays), which then gave a value for the true visibilities. This first version of the simulation only mimics a one dimensional redundant telescope array detecting a small amount of sources located in the volume above the antenna plane. Future versions, using GPUs, will handle a two dimensional redundant array of telescopes detecting a large amount of sources in the volume above the array.

Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles

NASA Technical Reports Server (NTRS)

Mullinix, Daniel; Hall, Kenneth; Smith, Bruce; Corbin, Brian

2012-01-01

A low-cost beamformer phased array antenna has been developed for expendable launch vehicles, rockets, and missiles. It utilizes a conformal array antenna of ring or individual radiators (design varies depending on application) that is designed to be fed by the recently developed hybrid electrical/mechanical (vendor-supplied) phased array beamformer. The combination of these new array antennas and the hybrid beamformer results in a conformal phased array antenna that has significantly higher gain than traditional omni antennas, and costs an order of magnitude or more less than traditional phased array designs. Existing omnidirectional antennas for sounding rockets, missiles, and expendable launch vehicles (ELVs) do not have sufficient gain to support the required communication data rates via the space network. Missiles and smaller ELVs are often stabilized in flight by a fast (i.e. 4 Hz) roll rate. This fast roll rate, combined with vehicle attitude changes, greatly increases the complexity of the high-gain antenna beam-tracking problem. Phased arrays for larger ELVs with roll control are prohibitively expensive. Prior techniques involved a traditional fully electronic phased array solution, combined with highly complex and very fast inertial measurement unit phased array beamformers. The functional operation of this phased array is substantially different from traditional phased arrays in that it uses a hybrid electrical/mechanical beamformer that creates the relative time delays for steering the antenna beam via a small physical movement of variable delay lines. This movement is controlled via an innovative antenna control unit that accesses an internal measurement unit for vehicle attitude information, computes a beam-pointing angle to the target, then points the beam via a stepper motor controller. The stepper motor on the beamformer controls the beamformer variable delay lines that apply the appropriate time delays to the individual array elements to properly

MSAT-X phased array antenna adaptions to airborne applications

NASA Technical Reports Server (NTRS)

Sparks, C.; Chung, H. H.; Peng, S. Y.

1988-01-01

The Mobile Satellite Experiment (MSAT-X) phased array antenna is being modified to meet future requirements. The proposed system consists of two high gain antennas mounted on each side of a fuselage, and a low gain antenna mounted on top of the fuselage. Each antenna is an electronically steered phased array based on the design of the MSAT-X antenna. A beamforming network is connected to the array elements via coaxial cables. It is essential that the proposed antenna system be able to provide an adequate communication link over the required space coverage, which is 360 degrees in azimuth and from 20 degrees below the horizon to the zenith in elevation. Alternative design concepts are suggested. Both open loop and closed loop backup capabilities are discussed. Typical antenna performance data are also included.

Ultrafast Pulse Generation in an Organic Nanoparticle-Array Laser.

PubMed

Daskalakis, Konstantinos S; Väkeväinen, Aaro I; Martikainen, Jani-Petri; Hakala, Tommi K; Törmä, Päivi

2018-04-11

Nanoscale coherent light sources offer potentially ultrafast modulation speeds, which could be utilized for novel sensors and optical switches. Plasmonic periodic structures combined with organic gain materials have emerged as promising candidates for such nanolasers. Their plasmonic component provides high intensity and ultrafast nanoscale-confined electric fields, while organic gain materials offer fabrication flexibility and a low acquisition cost. Despite reports on lasing in plasmonic arrays, lasing dynamics in these structures have not been experimentally studied yet. Here we demonstrate, for the first time, an organic dye nanoparticle-array laser with more than a 100 GHz modulation bandwidth. We show that the lasing modulation speed can be tuned by the array parameters. Accelerated dynamics is observed for plasmonic lasing modes at the blue side of the dye emission.

Microstrip patch antenna receiving array operating in the Ku band

NASA Technical Reports Server (NTRS)

Walcher, Douglas A.

1996-01-01

Microstrip patch antennas were first investigated from the idea that it would be highly advantageous to fabricate radiating elements (antennas) on the same dielectric substrate as RF circuitry and transmission lines. Other advantages were soon discovered to be its lightweight, low profile, conformability to shaped surfaces, and low manufacturing costs. Unfortunately, these same patches continually exhibit narrow bandwidths, wide beamwidths, and low antenna gain. This thesis will present the design and experimental results of a microstrip patch antenna receiving array operating in the Ku band. An antenna array will be designed in an attempt to improve its performance over a single patch. Most Ku band information signals are either wide band television images or narrow band data and voice channels. An attempt to improve the gain of the array by introducing parasitic patches on top of the array will also be presented in this thesis.

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.

Array feed synthesis for correction of reflector distortion and Vernier beamsteering

NASA Technical Reports Server (NTRS)

Blank, Stephen J.; Imbriale, William A.

1988-01-01

An algorithmic procedure for the synthesis of planar array feeds for paraboloidal reflectors is described which simultaneously provides electronic correction of systematic reflector surface distortions as well as a Vernier electronic beamsteering capability. Simple rules of thumb for the optimum chioce of planar array feed configuration (i.e., the number and type of elements) are derived from a parametric study made using the synthesis procedure. A number of f/D ratios and distortion models were examined that are typical of large paraboloidal reflectors. Numerical results are presented showing that, for the range of distortion models considered, good on-axis gain restoration can be achieved with as few as seven elements. For beamsteering to +/- 1 beamwidth (BW), 19 elements are required. For arrays with either 7 or 19 elements, the results indicate that the use of high-aperture-efficiency elements (e.g., disk-on-rod and short backfire) in the array yields higher system gain than can be obtained with elements having lower aperture efficiency (e.g., open-ended waveguides). With 37 elements, excellent gain and beamsteering performance to +/- 1.5 BW are obtained independent of the assumed effective aperture of the array element. An approximate expression is derived for the focal-plane field distribution of the distorted reflector. Contour plots of the focal-plane fields are also presented for various distortion and beam scan angle cases. The results obtained show the effectiveness of the array feed approach.

Array feed synthesis for correction of reflector distortion and Vernier Beamsteering

NASA Technical Reports Server (NTRS)

Blank, S. J.; Imbriale, W. A.

1986-01-01

An algorithmic procedure for the synthesis of planar array feeds for paraboloidal reflectors is described which simultaneously provides electronic correction of systematic reflector surface distortions as well as a Vernier electronic beamsteering capability. Simple rules of thumb for the optimum choice of planar array feed configuration (i.e., number and type of elements) are derived from a parametric study made using the synthesis procedure. A number of f/D ratios and distortion models were examined that are typical of large paraboloidal reflectors. Numerical results are presented showing that, for the range of distortion models considered, good on-axis gain restoration can be achieved with as few as seven elements. For beamsteering to +/- 1 beamwidth (BW), 19 elements are required. For arrays with either 7 or 19 elements, the results indicate that the use of high-aperture-efficiency elements (e.g., disk-on-rod and short backfire) in the array yields higher system gain than can be obtained with elements having lower aperture efficiency (e.g., open-ended waveguides). With 37 elements, excellent gain and beamsteering performance to +/- 1.5 BW are obtained independent of the assumed effective aperture of the array element. An approximate expression is derived for the focal-plane field distribution of the distorted reflector. Contour plots of the focal-plane fields are also presented for various distortion and beam scan angle cases. The results obtained show the effectiveness of the array feed approach.

Study of the characteristics of reconfigurable plasma antenna array

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

Alias, Nur Salihah; Dagang, Ahmad Nazri; Ali, Mohd Tarmizi

This paper presents a design and simulation of a reconfigurable array of plasma antenna. The plasma column is used as radiating elements instead of metal to create an antenna. The advantages of the plasma antenna over the conventional antenna are its possible to change the operating parameters, such as the working pressure, input power, radius of the discharge tube, resonant frequency, and length of the plasma column. In addition, plasma antenna can be reconfigurable with respect to shape, frequency and radiation parameters in a very short time. The plasma discharge tube was designed with a length of 200 mm, the radiusmore » of the plasma column was 2.5 mm and the coupling sleeve was connected to the SMA as the ground. This simulation was performed by using the simulation software Computer Simulation Technology (CST). The frequency is set in the range of 1 GHz to 10 GHz. The performance of the designed antenna was analyzed in term of return loss, gain and radiation pattern. For reconfigurable plasma antenna array, it shows that the gain is increase when the number of antenna element is increase. The combination of the discharge tube and metal rod as an antenna array has been done, and the result shows that an array with the plasma element can achieve higher gain.« less

Repressing a Repressor

PubMed Central

Silverstone, Aron L.; Jung, Hou-Sung; Dill, Alyssa; Kawaide, Hiroshi; Kamiya, Yuji; Sun, Tai-ping

2001-01-01

RGA (for repressor of ga1-3) and SPINDLY (SPY) are likely repressors of gibberellin (GA) signaling in Arabidopsis because the recessive rga and spy mutations partially suppressed the phenotype of the GA-deficient mutant ga1-3. We found that neither rga nor spy altered the GA levels in the wild-type or the ga1-3 background. However, expression of the GA biosynthetic gene GA4 was reduced 26% by the rga mutation, suggesting that partial derepression of the GA response pathway by rga resulted in the feedback inhibition of GA4 expression. The green fluorescent protein (GFP)–RGA fusion protein was localized to nuclei in transgenic Arabidopsis. This result supports the predicted function of RGA as a transcriptional regulator based on sequence analysis. Confocal microscopy and immunoblot analyses demonstrated that the levels of both the GFP-RGA fusion protein and endogenous RGA were reduced rapidly by GA treatment. Therefore, the GA signal appears to derepress the GA signaling pathway by degrading the repressor protein RGA. The effect of rga on GA4 gene expression and the effect of GA on RGA protein level allow us to identify part of the mechanism by which GA homeostasis is achieved. PMID:11449051

Multicolor photonic crystal laser array

DOEpatents

Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

2015-04-28

A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas

NASA Astrophysics Data System (ADS)

Poduval, Dhruva

Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must be understood and optimized under multiple design constraints, e.g. substrate material properties and thicknesses, element to element spacing, and feed lines and their orientation and arrangements with respect to the antenna elements. The focus of this thesis is to investigate, design, and develop an aperture coupled patch array with wide operating bandwidth (30%), high gain (17.5 dBi), low side lobe level (20 dB), and high Forward to Backward (F/B) ratio (21.8 dB). The target frequency range is 2.4 to 3 GHz given its wide application in WLAN, LTE (Long Term Evolution) and other communication systems. Notwithstanding that the design concept can very well be adapted at other frequencies. Specifically, a 16 element, 4 by 4 planar microstrip patch array is designed using HFSS and experimentally developed and tested. Starting from mutual coupling minimization a corporate feeding scheme is designed to achieve the needed performance. To reduce the SLL the corporate feeding network is redesigned to obtain a specific amplitude taper. Studies are conducted to determine the optimum location for a metallic reflector under the feed line to improve the F/B. An experimental prototype of the antenna was built and tested validating and demonstrating the performance levels expected from simulation predictions

Compensation of relector antenna surface distortion using an array feed

NASA Technical Reports Server (NTRS)

Cherrette, A. R.; Acosta, R. J.; Lam, P. T.; Lee, S. W.

1988-01-01

The dimensional stability of the surface of a large reflector antenna is important when high gain or low sidelobe performance is desired. If the surface is distorted due to thermal or structural reasons, antenna performance can be improved through the use of an array feed. The design of the array feed and its relation to the surface distortion are examined. The sensitivity of antenna performance to changing surface parameters for fixed feed array geometries is also studied. This allows determination of the limits of usefulness for feed array compensation.

Factors affecting the performance of large-aperture microphone arrays.

PubMed

Silverman, Harvey F; Patterson, William R; Sachar, Joshua

2002-05-01

Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m x 8 m x 3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

Factors affecting the performance of large-aperture microphone arrays

NASA Astrophysics Data System (ADS)

Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

2002-05-01

Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

Endoluminal ultrasound applicator configurations utilizing deployable arrays, reflectors and lenses to augment and dynamically adjust treatment volume, gain, and depth

NASA Astrophysics Data System (ADS)

Adams, Matthew S.; Salgaonkar, Vasant A.; Sommer, Graham; Diederich, Chris J.

2017-02-01

Endoluminal high-intensity ultrasound offers spatially-precise thermal ablation of tissues adjacent to body lumens, but is constrained in treatment volume and penetration depth by the effective aperture of integrated transducers, which are limited in size to enable delivery through anatomical passages, endoscopic instrumentation, or laparoscopic ports. This study introduced and investigated three distinct endoluminal ultrasound applicator designs that can be delivered in a compact state then deployed or expanded at the target luminal site to increase the effective therapeutic aperture. The first design incorporated an array of planar transducers which could be unfolded at specific angles of convergence between the transducers. Two alternative designs consisted of fixed transducer sources surrounded by an expandable multicompartment balloon that contained acoustic reflector and dynamically-adjustable fluid lenses compartments. Parametric studies of acoustic output were performed across device design parameters via the rectangular radiator and secondary sources methods. Biothermal models were used to simulate resulting temperature distributions in three-dimensional heterogeneous tissue models. Simulations indicate that a deployable transducer array can increase volumetric coverage and penetration depth by 80% and 20%, respectively, while permitting more conformal thermal lesion shapes based on the degree of convergence between the transducers. The applicator designs incorporating reflector and fluid lenses demonstrated enhanced focal gain and penetration depth that increased with the diameter of the expanded reflector-lens balloon. Thermal simulations of assemblies with 12 mm compact profiles and 50 mm expanded balloon diameters demonstrated generation of localized thermal lesions at depths up to 10 cm in liver tissue.

Design and Development of 256x256 Linear Mode Low-Noise Avalanche Photodiode Arrays

NASA Technical Reports Server (NTRS)

Yuan, Ping; Sudharsanan, Rengarajan; Bai, Xiaogang; Boisvert, Joseph; McDonald, Paul; Chang, James

2011-01-01

A larger format photodiode array is always desirable for many LADAR imaging applications. However, as the array format increases, the laser power or the lens aperture has to increase to maintain the same flux per pixel thus increasing the size, weight and power of the imaging system. In order to avoid this negative impact, it is essential to improve the pixel sensitivity. The sensitivity of a short wavelength infrared linear-mode avalanche photodiode (APD) is a delicate balance of quantum efficiency, usable gain, excess noise factor, capacitance, and dark current of APD as well as the input equivalent noise of the amplifier. By using InA1As as a multiplication layer in an InP-based APD, the ionization coefficient ratio, k, is reduced from 0.40 (lnP) to 0.22, and the excess noise is reduced by about 50%. An additional improvement in excess noise of 25% was achieved by employing an impact-ionization-engineering structure with a k value of 0.15. Compared with the traditional InP structure, about 30% reduction in the noise-equivalent power with the following amplifier can be achieved. Spectrolab demonstrated 30-um mesa APD pixels with a dark current less than 10 nA and a capacitance of 60 fF at gain of 10. APD gain uninformity determines the usable gain of most pixels in an array, which is critical to focal plane array sensitivity. By fine tuning the material growth and device process, a break-down-voltage standard deviation of 0.1 V and gain of 30 on individual pixels were demonstrated in our 256x256 linear-mode APD arrays.

Reliability of high-power QCW arrays

NASA Astrophysics Data System (ADS)

Feeler, Ryan; Junghans, Jeremy; Remley, Jennifer; Schnurbusch, Don; Stephens, Ed

2010-02-01

Northrop Grumman Cutting Edge Optronics has developed a family of arrays for high-power QCW operation. These arrays are built using CTE-matched heat sinks and hard solder in order to maximize the reliability of the devices. A summary of a recent life test is presented in order to quantify the reliability of QCW arrays and associated laser gain modules. A statistical analysis of the raw lifetime data is presented in order to quantify the data in such a way that is useful for laser system designers. The life tests demonstrate the high level of reliability of these arrays in a number of operating regimes. For single-bar arrays, a MTTF of 19.8 billion shots is predicted. For four-bar samples, a MTTF of 14.6 billion shots is predicted. In addition, data representing a large pump source is analyzed and shown to have an expected lifetime of 13.5 billion shots. This corresponds to an expected operational lifetime of greater than ten thousand hours at repetition rates less than 370 Hz.

Intensity dynamics in a waveguide array laser

NASA Astrophysics Data System (ADS)

Feng, Mingming; Williams, Matthew O.; Kutz, J. Nathan; Silverman, Kevin L.; Mirin, Richard P.; Cundiff, Steven T.

2011-02-01

We consider experimentally and theoretically the optical field dynamics of a five-emitter laser array subject to a ramped injection current. We have achieved experimentally an array that produces a robust oscillatory power output with a nearly constant π phase shift between the oscillations from each waveguide. The output power also decreases linearly as a function of waveguide number. Those behaviors persisted for pump currents varying between 380 and 500 mA with only a slight change in phase. Of note is the fact that the fundamental frequency of oscillation increases with injection current, and higher harmonics are produced above a threshold current of approximately 380 mA. Experimental observations and theoretical predictions are in agreement. A low dimensional model was also developed and the impact of the nonuniform injection current studied. A nonuniform injection current is capable of shifting the bifurcations of the waveguide array providing a valuable method of array tuning without additional gain or structural alterations to the array.

The development and test of ultra-large-format multi-anode microchannel array detector systems

NASA Technical Reports Server (NTRS)

Timothy, J. G.

1984-01-01

The specific tasks that were accomplished with each of the key elements of the multi-anode microchannel array detector system are described. The modes of operation of position-sensitive electronic readout systems for use with high-gain microchannel plates are described and their performance characteristics compared and contrasted. Multi-anode microchannel array detector systems with formats as large as 256 x 1024 pixels are currently under evaluation. Preliminary performance data for sealed ultraviolet and visible-light detector tubes show that the detector systems have unique characteristics which make them complementary to photoconductive array detectors, such as CCDs, and superior to alternative pulse-counting detector systems employing high-gain MCPs.

A Temperature-Based Gain Calibration Technique for Precision Radiometry

NASA Astrophysics Data System (ADS)

Parashare, Chaitali Ravindra

Detecting extremely weak signals in radio astronomy demands high sensitivity and stability of the receivers. The gain of a typical radio astronomy receiver is extremely large, and therefore, even very small gain instabilities can dominate the received noise power and degrade the instrument sensitivity. Hence, receiver stabilization is of prime importance. Gain variations occur mainly due to ambient temperature fluctuations. We take a new approach to receiver stabilization, which makes use of active temperature monitoring and corrects for the gain fluctuations in post processing. This approach is purely passive and does not include noise injection or switching for calibration. This system is to be used for the Precision Array for Probing the Epoch of Reionization (PAPER), which is being developed to detect the extremely faint neutral hydrogen (HI) signature of the Epoch of Reionization (EoR). The epoch of reionization refers to the period in the history of the Universe when the first stars and galaxies started to form. When there are N antenna elements in the case of a large scale array, all elements may not be subjected to the same environmental conditions at a given time. Hence, we expect to mitigate the gain variations by monitoring the physical temperature of each element of the array. This stabilization approach will also benefit experiments like EDGES (Experiment to Detect the Global EoR Signature) and DARE (Dark Ages Radio Explorer), which involve a direct measurement of the global 21 cm signal using a single antenna element and hence, require an extremely stable system. This dissertation focuses on the development and evaluation of a calibration technique that compensates for the gain variations caused due to temperature fluctuations of the RF components. It carefully examines the temperature dependence of the components in the receiver chain. The results from the first-order field instrument, called a Gainometer (GoM), highlight the issue with the cable

A microfabricated low-profile wideband antenna array for terahertz communications.

PubMed

Luk, K M; Zhou, S F; Li, Y J; Wu, F; Ng, K B; Chan, C H; Pang, S W

2017-04-28

While terahertz communications are considered to be the future solutions for the increasing demands on bandwidth, terahertz equivalents of radio frequency front-end components have not been realized. It remains challenging to achieve wideband, low profile antenna arrays with highly directive beams of radiation. Here, based on the complementary antenna approach, a wideband 2 × 2 cavity-backed slot antenna array with a corrugated surface is proposed. The approach is based on a unidirectional antenna with a cardiac radiation pattern and stable frequency characteristics that is achieved by integrating a series-resonant electric dipole with a parallel-resonant magnetic dipole. In this design, the slots work as magnetic dipoles while the corrugated surface radiates as an array of electric dipoles. The proposed antenna is realized at 1 THz operating frequency by stacking multiple metallized layers using the microfabrication technology. S-parameter measurements of this terahertz low-profile metallic antenna array demonstrate high efficiency at terahertz frequencies. Fractional bandwidth and gain are measured to be 26% and 14 dBi which are consistent with the simulated results. The proposed antenna can be used as the building block for larger antenna arrays with more directive beams, paving the way to develop high gain low-profile antennas for future communication needs.

A Study of Phased Array Antennas for NASA's Deep Space Network

NASA Technical Reports Server (NTRS)

Jamnejad, Vahraz; Huang, John; Cesarone, Robert J.

2001-01-01

In this paper we briefly discuss various options but focus on the feasibility of the phased arrays as a viable option for this application. Of particular concern and consideration will be the cost, reliability, and performance compared to the present 70-meter antenna system, particularly the gain/noise temperature levels in the receive mode. Many alternative phased arrays including planar horizontal arrays, hybrid mechanically/electronically steered arrays, phased array of mechanically steered reflectors, multi-faceted planar arrays, phased array-fed lens antennas, and planar reflect-arrays are compared and their viability is assessed. Although they have many advantages including higher reliability, near-instantaneous beam switching or steering capability, the cost of such arrays is presently prohibitive and it is concluded that the only viable array options at the present are the arrays of a few or many small reflectors. The active planar phased arrays, however, may become feasible options in the next decade and can be considered for deployment in smaller configurations as supplementary options.

Adaptive multibeam phased array design for a Spacelab experiment

NASA Technical Reports Server (NTRS)

Noji, T. T.; Fass, S.; Fuoco, A. M.; Wang, C. D.

1977-01-01

The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio.

Transformation from a Single Antenna to a Series Array Using Push/Pull Origami

PubMed Central

Shah, Syed Imran Hussain

2017-01-01

We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5–2.65 GHz and 2.48–2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications. PMID:28846603

Transformation from a Single Antenna to a Series Array Using Push/Pull Origami.

PubMed

Shah, Syed Imran Hussain; Lim, Sungjoon

2017-08-26

We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5-2.65 GHz and 2.48-2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications.

A 400 KHz line rate 2048-pixel stitched SWIR linear array

NASA Astrophysics Data System (ADS)

Anchlia, Ankur; Vinella, Rosa M.; Gielen, Daphne; Wouters, Kristof; Vervenne, Vincent; Hooylaerts, Peter; Deroo, Pieter; Ruythooren, Wouter; De Gaspari, Danny; Das, Jo; Merken, Patrick

2016-05-01

Xenics has developed a family of stitched SWIR long linear arrays that operate up to 400 KHz of line rate. These arrays serve medical and industrial applications that require high line rates as well as space applications that require long linear arrays. The arrays are based on a modular ROIC design concept: modules of 512 pixels are stitched during fabrication to achieve 512, 1024 and 2048 pixel arrays. Each 512-pixel module has its own on-chip digital sequencer, analog readout chain and 4 output buffers. This modular concept enables a long array to run at a high line rates irrespective of the array length, which limits the line rate in a traditional linear array. The ROIC is flip-chipped with InGaAs detector arrays. The FPA has a pixel pitch of 12.5μm and has two pixel flavors: square (12.5μm) and rectangular (250μm). The frontend circuit is based on Capacitive Trans-impedance Amplifier (CTIA) to attain stable detector bias, and good linearity and signal integrity, especially at high speeds. The CTIA has an input auto-zero mechanism that allows to have low detector bias (<20mV). An on-chip Correlated Double Sample (CDS) facilitates removal of CTIA KTC and 1/f noise, and other offsets, achieving low noise performance. There are five gain modes in the FPA giving the full well range from 85Ke- to 40Me-. The measured input referred noise is 35e-rms in the highest gain mode. The FPA operates in Integrate While Read mode and, at a master clock rate of 60MHz and a minimum integration time of 1.4μs, achieves the highest line rate of 400 KHz. In this paper, design details and measurements results are presented in order to demonstrate the array performance.

A Robust Sound Source Localization Approach for Microphone Array with Model Errors

NASA Astrophysics Data System (ADS)

Xiao, Hua; Shao, Huai-Zong; Peng, Qi-Cong

In this paper, a robust sound source localization approach is proposed. The approach retains good performance even when model errors exist. Compared with previous work in this field, the contributions of this paper are as follows. First, an improved broad-band and near-field array model is proposed. It takes array gain, phase perturbations into account and is based on the actual positions of the elements. It can be used in arbitrary planar geometry arrays. Second, a subspace model errors estimation algorithm and a Weighted 2-Dimension Multiple Signal Classification (W2D-MUSIC) algorithm are proposed. The subspace model errors estimation algorithm estimates unknown parameters of the array model, i. e., gain, phase perturbations, and positions of the elements, with high accuracy. The performance of this algorithm is improved with the increasing of SNR or number of snapshots. The W2D-MUSIC algorithm based on the improved array model is implemented to locate sound sources. These two algorithms compose the robust sound source approach. The more accurate steering vectors can be provided for further processing such as adaptive beamforming algorithm. Numerical examples confirm effectiveness of this proposed approach.

Distributed phased array architecture study

NASA Technical Reports Server (NTRS)

Bourgeois, Brian

1987-01-01

Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

Micro-array versus nano-array platforms: a comparative study for ODN detection based on SPR enhanced ellipsometry

NASA Astrophysics Data System (ADS)

Celen, Burcu; Demirel, Gökhan; Piskin, Erhan

2011-04-01

The rapid and sensitive detection of DNA has recently attracted worldwide attention for a variety of disease diagnoses and detection of harmful bacteria in food and drink. In this paper, we carried out a comparative study based on surface plasmon resonance enhanced ellipsometry (SPREE) for the detection of oligodeoxynucleotides (ODNs) using micro- and nano-array platforms. The micro-arrayed surfaces were fabricated by a photolithography approach using different types of mask having varying size and shape. Well-ordered arrays of high aspect ratio polymeric nanotubes were also obtained using high molecular weight polystyrene (PS) and anodic aluminum oxide (AAO) membranes having 200 nm pore diameters. The SPREE sensors were then prepared by direct coupling of thiolated probe-ODNs, which contain suitable spacer arms, on gold-coated micro- and nano-arrayed surfaces. We experimentally demonstrated that, for the first time, gold-coated free standing polymeric nano-arrayed platforms can easily be produced and lead to a significant sensor sensitivity gain compared to that of the conventional SPREE surfaces of about four times. We believe that such an enhancement in sensor response could be useful for next generation sensor systems.

Theoretical analysis of phase locking in an array of globally coupled lasers

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

Vysotskii, D V; Elkin, N N; Napartovich, A P

2013-09-30

A model of an array of globally coupled fibre lasers, with the same fraction of the total output beam power injected into each laser, is considered. Phase self-locking of the laser array makes it possible to increase the brightness of the total output beam without any devices for controlling the phases of output beams, which significantly complicate the laser system. The spread of the laser optical lengths is several hundreds of wavelengths (or even more); within the theory of hollow cavities, this spread should lead to a fast decrease in the total power with an increase in the number ofmore » lasers. The presence of the active medium may reduce this drop to a great extent due to the self-tuning of the laser array radiation wavelength to a value providing a maximum gain for the array lasing mode. The optical length of each element is assumed to be random. The increase in the phase-locking efficiency due to the gain saturation is explained based on the probabilistic approach. An iterative procedure is developed to find the array output power in the presence of steady-state phase locking. Calculations for different values of small-signal gain and the output-power fraction spent on global coupling are performed. It is shown that, when this fraction amounts to ∼20 % – 30 %, phase locking of up to 20 fibre lasers can be implemented with an efficiency as high as 70 %. (control of laser radiation parameters)« less

Scene-based nonuniformity correction for focal plane arrays by the method of the inverse covariance form.

PubMed

Torres, Sergio N; Pezoa, Jorge E; Hayat, Majeed M

2003-10-10

What is to our knowledge a new scene-based algorithm for nonuniformity correction in infrared focal-plane array sensors has been developed. The technique is based on the inverse covariance form of the Kalman filter (KF), which has been reported previously and used in estimating the gain and bias of each detector in the array from scene data. The gain and the bias of each detector in the focal-plane array are assumed constant within a given sequence of frames, corresponding to a certain time and operational conditions, but they are allowed to randomly drift from one sequence to another following a discrete-time Gauss-Markov process. The inverse covariance form filter estimates the gain and the bias of each detector in the focal-plane array and optimally updates them as they drift in time. The estimation is performed with considerably higher computational efficiency than the equivalent KF. The ability of the algorithm in compensating for fixed-pattern noise in infrared imagery and in reducing the computational complexity is demonstrated by use of both simulated and real data.

Semiconductor radiation detector with internal gain

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

Iwanczyk, Jan; Patt, Bradley E.; Vilkelis, Gintas

An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

Adaptive Waveform Correlation Detectors for Arrays: Algorithms for Autonomous Calibration

DTIC Science & Technology

2007-09-01

March 17, 2005. The seismic signals from both master and detected events are followed by infrasound arrivals. Note the long duration of the...correlation coefficient traces with a significant array -gain. A detected event that is co-located with the master event will record the same time-difference...estimating the detection threshold reduction for a range of highly repeating seismic sources using arrays of different configurations and at different

Characterization of tapered slot antenna feeds and feed arrays

NASA Technical Reports Server (NTRS)

Kim, Young-Sik; Yngvesson, K. Sigfrid

1990-01-01

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

Turbulent chimeras in large semiconductor laser arrays

PubMed Central

Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

2017-01-01

Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure. PMID:28165053

Turbulent chimeras in large semiconductor laser arrays

NASA Astrophysics Data System (ADS)

Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

2017-02-01

Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

Active medium gain study of electric-discharge oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Kolobyanin, Yuriy; Adamenkov, Yuriy; Vyskubenko, Boris; Goryachev, Leonid; Ilyin, Sergey; Kalashnik, Anatoliy; Rakhimova, Tatiana; Rogozhnikov, Georgiy

2007-05-01

The paper reports on experimental studies of the active medium gain in supersonic electric-discharge oxygen-iodine laser (DOIL) based on traveling mw discharge. The measurements have included: absolute concentration, yield, and energy efficiency of production of SO in pure oxygen and oxygen-helium mixes at an oxygen partial pressure 3 to 15 Torr. For the gas flow to get rid of atomic oxygen, both heterogeneous mercury oxide coatings of the tube walls and homogeneous additives to the work mix, such as nitrogen oxide, have been used. The active medium of DOIL was formed using a nozzle array of the type of ejector sized as 10*50 mm2. The singlet oxygen-helium mix was supplied through three rows of sonic cylindrical nozzles, while the iodine-carrier gas mix - through two rows of supersonic conical nozzles with a half-opening angle of 10°(arc). The gas-phase iodine was produced in a quartz cell filled with iodine crystals. Room-temperature iodine vapors were picked up with a carrier gas (nitrogen or helium) and thus delivered into the nozzle array. The active medium was investigated by the high-resolution laser diode spectroscopy approach that used the laser type Vortex 6025 purchased from New Focus, Inc. The laser medium gain factor was determined by the intra-cavity approach having a sensitivity about 1*10 -6 cm -1. The static temperature of the medium was determined from the measurements of gain half-width. The gain of the active medium of electric-discharge OIL has been investigated. The DOIL in use was operating on a mix composed as O II:He=1:1 at a total pressure of 6 Torr and flowrate - about 1 mmol/s. With helium as an iodine carrier gas at a flowrate ~3 mmol/s, we have recorded a positive gain in the DOIL medium.

Microstrip antenna arrays with parasitic elements

NASA Technical Reports Server (NTRS)

Lee, Kai-Fong

1996-01-01

This research was concerned with using parasitic elements to improve the bandwidth, gain and axial ratio characteristics of microstrip antennas and arrays. Significant improvements in these characteristics were obtained using stacked and coplanar parasitic elements. Details of the results are described in a total of 16 journal and 17 conference papers. These are listed in Section four of this report.

Ku-Band Traveling Wave Slot Array Using Simple Scanning Control

NASA Technical Reports Server (NTRS)

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

2015-01-01

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

A New Wideband, Fully Steerable, Decametric Array at Clark Lake

NASA Technical Reports Server (NTRS)

Erickson, W. C.; Fisher, J. R.

1974-01-01

A fully steerable, decametric array for radio astronomy is under construction at the Clark Lake Radio Observatory near Borrego Springs, California. This array will be a T of 720 conical spiral antennas (teepee-shaped antennas, hence the array is called the TPT), 3.0 km by 1.8 km capable of operating between 15 and 125 MHz. Both its operating frequency and beam position will be adjustable in less than one millisecond, and the TPT will provide a 49-element picture around the central beam position for extended source observations. Considerable experience was gained in the operation of completed portions of the array, and successful operation of the final array is assured. The results are described of the tests which were conducted with the conical spirals, and the planned electronics and data processing systems are described.

A QTL for root growth angle on rice chromosome 7 is involved in the genetic pathway of DEEPER ROOTING 1.

PubMed

Uga, Yusaku; Kitomi, Yuka; Yamamoto, Eiji; Kanno, Noriko; Kawai, Sawako; Mizubayashi, Tatsumi; Fukuoka, Shuichi

2015-01-01

Root growth angle (RGA) is an important trait that influences the ability of rice to avoid drought stress. DEEPER ROOTING 1 (DRO1), which is a major quantitative trait locus (QTL) for RGA, is responsible for the difference in RGA between the shallow-rooting cultivar IR64 and the deep-rooting cultivar Kinandang Patong. However, the RGA differences between these cultivars cannot be fully explained by DRO1. The objective of this study was to identify new QTLs for RGA explaining the difference in RGA between these cultivars. By crossing IR64 (which has a non-functional allele of DRO1) with Kinandang Patong (which has a functional allele of DRO1), we developed 26 chromosome segment substitution lines (CSSLs) that carried a particular chromosome segment from Kinandang Patong in the IR64 genetic background. Using these CSSLs, we found only one chromosomal region that was related to RGA: on chromosome 9, which includes DRO1. Using an F2 population derived from a cross between Kinandang Patong and the Dro1-NIL (near isogenic line), which had a functional DRO1 allele in the IR64 genetic background, we identified a new QTL for RGA (DRO3) on the long arm of chromosome 7. DRO3 may only affect RGA in plants with a functional DRO1 allele, suggesting that DRO3 is involved in the DRO1 genetic pathway.

Effects of wind waves on horizontal array performance in shallow-water conditions

NASA Astrophysics Data System (ADS)

Zavol'skii, N. A.; Malekhanov, A. I.; Raevskii, M. A.; Smirnov, A. V.

2017-09-01

We analyze the influence of statistical effects of the propagation of an acoustic signal excited by a tone source in a shallow-water channel with a rough sea surface on the efficiency of a horizontal phased array. As the array characteristics, we consider the angular function of the array response for a given direction to the source and the coefficient of amplification of the signal-to-noise ratio (array gain). Numerical simulation was conducted in to the winter hydrological conditions of the Barents Sea in a wide range of parameters determining the spatial signal coherence. The results show the main physical effects of the influence of wind waves on the array characteristics and make it possible to quantitatively predict the efficiency of a large horizontal array in realistic shallow-water channels.

Adaptive Injection-locking Oscillator Array for RF Spectrum Analysis

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

Leung, Daniel

2011-04-19

A highly parallel radio frequency receiver using an array of injection-locking oscillators for on-chip, rapid estimation of signal amplitudes and frequencies is considered. The oscillators are tuned to different natural frequencies, and variable gain amplifiers are used to provide negative feedback to adapt the locking band-width with the input signal to yield a combined measure of input signal amplitude and frequency detuning. To further this effort, an array of 16 two-stage differential ring oscillators and 16 Gilbert-cell mixers is designed for 40-400 MHz operation. The injection-locking oscillator array is assembled on a custom printed-circuit board. Control and calibration is achievedmore » by on-board microcontroller.« less

Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

DTIC Science & Technology

1983-01-01

radiators ....... ............ 4 1-2 HF heating array ........ ................... 9 1-3 HF heating array element ...... ................ 9 1-4 View of top...elements looking down at pyramid ....... 9 1-5 Non-planar log-periodic antenna semi-structure dimensions ............ . ....... 10 l-6a Power gain vs...22 1-8 Orientation of 4- and 8-element arrays .. ......... .. 24 1- 9 Comparison of experimental and theoretical patterns. . . 27 1-10 Directive

A 7T Spine Array Based on Electric Dipole Transmitters

PubMed Central

Duan, Qi; Nair, Govind; Gudino, Natalia; de Zwart, Jacco A.; van Gelderen, Peter; Murphy-Boesch, Joe; Reich, Daniel S.; Duyn, Jeff H.; Merkle, Hellmut

2015-01-01

Purpose In this work the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high field is explored. Method A 2-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining 8 loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared to a design using quadrature loop pairs. The radio-frequency (RF) energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies. Results The results indicate dramatically improved transmit efficiency for the dipole design as compared to the loop excitation. Up to 76% gain was achieved within the spinal region. Conclusion For imaging of the spine, electric-dipole based transmitters provided an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high field. PMID:26190585

2D Ruddlesden-Popper Perovskites Microring Laser Array.

PubMed

Zhang, Haihua; Liao, Qing; Wu, Yishi; Zhang, Zhaoyi; Gao, Qinggang; Liu, Peng; Li, Meili; Yao, Jiannian; Fu, Hongbing

2018-04-01

3D organic-inorganic hybrid perovskites have featured high gain coefficients through the electron-hole plasma stimulated emission mechanism, while their 2D counterparts of Ruddlesden-Popper perovskites (RPPs) exhibit strongly bound electron-hole pairs (excitons) at room temperature. High-performance solar cells and light-emitting diodes (LEDs) are reported based on 2D RPPs, whereas light-amplification devices remain largely unexplored. Here, it is demonstrated that ultrafast energy transfer along cascade quantum well (QW) structures in 2D RPPs concentrates photogenerated carriers on the lowest-bandgap QW state, at which population inversion can be readily established enabling room-temperature amplified spontaneous emission and lasing. Gain coefficients measured for 2D RPP thin-films (≈100 nm in thickness) are found about at least four times larger than those for their 3D counterparts. High-density large-area microring arrays of 2D RPPs are fabricated as whispering-gallery-mode lasers, which exhibit high quality factor (Q ≈ 2600), identical optical modes, and similarly low lasing thresholds, allowing them to be ignited simultaneously as a laser array. The findings reveal that 2D RPPs are excellent solution-processed gain materials potentially for achieving electrically driven lasers and ideally for on-chip integration of nanophotonics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ku-Band Traveling Wave Slot Array Using Simple Scanning Control

NASA Technical Reports Server (NTRS)

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

2015-01-01

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

Effects of a reentry plasma sheath on the beam pointing properties of an array antenna

NASA Astrophysics Data System (ADS)

Bai, Bowen; Liu, Yanming; Lin, Xiaofang; Li, Xiaoping

2018-03-01

The reduction in the gain of an on-board antenna caused by a reentry plasma sheath is an important effect that contributes to the reentry "blackout" problem. Using phased array antenna and beamforming technology could provide higher gain and an increase in the communication signal intensity. The attenuation and phase delay of the electromagnetic (EM) waves transmitting through the plasma sheath are direction-dependent, and the radiation pattern of the phased array antenna is affected, leading to a deviation in the beam pointing. In this paper, the far-field pattern of a planar array antenna covered by a plasma sheath is deduced analytically by considering both refraction and mutual coupling effects. A comparison between the analytic results and the results from an electromagnetic simulation is carried out. The effect of the plasma sheath on the radiation pattern and the beam pointing errors of the phased array antenna is studied systematically, and the derived results could provide useful information for the correction of pointing errors.

Microstrip Yagi array for MSAT vehicle antenna application

NASA Technical Reports Server (NTRS)

Huang, John; Densmore, Arthur; Pozar, David

1990-01-01

A microstrip Yagi array was developed for the MSAT system as a low-cost mechanically steered medium-gain vehicle antenna. Because its parasitic reflector and director patches are not connected to any of the RF power distributing circuit, while still contributing to achieve the MSAT required directional beam, the antenna becomes a very efficient radiating system. With the complete monopulse beamforming circuit etched on a thin stripline board, the planar microstrip Yagi array is capable of achieving a very low profile. A theoretical model using the Method of Moments was developed to facilitate the ease of design and understanding of this antenna.

Integrated Solar-Panel Antenna Array for CubeSats

NASA Technical Reports Server (NTRS)

Baktur, Reyhan

2016-01-01

The goal of the Integrated Solar-Panel Antenna Array for CubeSats (ISAAC) project is to design and demonstrate an effective and efficien toptically transparent, high-gain, lightweight, conformal X-band antenna array that is integrated with the solar panels of a CubeSat. The targeted demonstration is for a Near Earth Network (NEN)radio at X-band, but the design can be easilyscaled to other network radios for higher frequencies. ISAAC is a less expensive and more flexible design for communication systemscompared to a deployed dish antenna or the existing integrated solar panel antenna design.

Parallel computing on Unix workstation arrays

NASA Astrophysics Data System (ADS)

Reale, F.; Bocchino, F.; Sciortino, S.

1994-12-01

We have tested arrays of general-purpose Unix workstations used as MIMD systems for massive parallel computations. In particular we have solved numerically a demanding test problem with a 2D hydrodynamic code, generally developed to study astrophysical flows, by exucuting it on arrays either of DECstations 5000/200 on Ethernet LAN, or of DECstations 3000/400, equipped with powerful Alpha processors, on FDDI LAN. The code is appropriate for data-domain decomposition, and we have used a library for parallelization previously developed in our Institute, and easily extended to work on Unix workstation arrays by using the PVM software toolset. We have compared the parallel efficiencies obtained on arrays of several processors to those obtained on a dedicated MIMD parallel system, namely a Meiko Computing Surface (CS-1), equipped with Intel i860 processors. We discuss the feasibility of using non-dedicated parallel systems and conclude that the convenience depends essentially on the size of the computational domain as compared to the relative processor power and network bandwidth. We point out that for future perspectives a parallel development of processor and network technology is important, and that the software still offers great opportunities of improvement, especially in terms of latency times in the message-passing protocols. In conditions of significant gain in terms of speedup, such workstation arrays represent a cost-effective approach to massive parallel computations.

Progress towards large gain-length products on the Li-like recombination scheme

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

Zeitoun, P.; Jamelot, G.; Carillon, A.

1995-05-01

Investigating possibilities of attaining large gain-length products on the recombination scheme using lithium-like ions, we have examined two approaches aimed at overcoming the problem of plasma non-uniformity susceptible to destroy gain by a number of processes. In the first approach we studied amplification on the transitions 5f-3d and 4f-3d in Li-like Al{sup 10+} plasma column produced by smoothing optics using lens arrays. Employing this device resulted in the gain holding up significantly longer than when no smoothing optics was used. Second, we have investigated numerically and experimentally the 5g-4f transition in Li-like S{sup 13+}, as the gain should be barelymore » affected by the plasma nonuniformities. Encouraging results were obtained and their various aspects are discussed.« less

CMOS-micromachined, two-dimenisional transistor arrays for neural recording and stimulation.

PubMed

Lin, J S; Chang, S R; Chang, C H; Lu, S C; Chen, H

2007-01-01

In-plane microelectrode arrays have proven to be useful tools for studying the connectivities and the functions of neural tissues. However, seldom microelectrode arrays are monolithically-integrated with signal-processing circuits, without which the maximum number of electrodes is limited by the compromise with routing complexity and interferences. This paper proposes a CMOS-compatible, two-dimensional array of oxide-semiconductor field-effect transistors(OSFETs), capable of both recording and stimulating neuronal activities. The fabrication of the OSFETs not only requires simply die-level, post-CMOS micromachining process, but also retains metal layers for monolithic integration with signal-processing circuits. A CMOS microsystem containing the OSFET arrays and gain-programmable recording circuits has been fabricated and tested. The preliminary testing results are presented and discussed.

VIIRS day-night band gain and offset determination and performance

NASA Astrophysics Data System (ADS)

Geis, J.; Florio, C.; Moyer, D.; Rausch, K.; De Luccia, F. J.

2012-09-01

On October 28th, 2011, the Visible-Infrared Imaging Radiometer Suite (VIIRS) was launched on-board the Suomi National Polar-orbiting Partnership (NPP) spacecraft. The instrument has 22 spectral bands: 14 reflective solar bands (RSB), 7 thermal emissive bands (TEB), and a Day Night Band (DNB). The DNB is a panchromatic, solar reflective band that provides visible through near infrared (IR) imagery of earth scenes with radiances spanning 7 orders of magnitude. In order to function over this large dynamic range, the DNB employs a focal plane array (FPA) consisting of three gain stages: the low gain stage (LGS), the medium gain stage (MGS), and the high gain stage (HGS). The final product generated from a DNB raw data record (RDR) is a radiance sensor data record (SDR). Generation of the SDR requires accurate knowledge of the dark offsets and gain coefficients for each DNB stage. These are measured on-orbit and stored in lookup tables (LUT) that are used during ground processing. This paper will discuss the details of the offset and gain measurement, data analysis methodologies, the operational LUT update process, and results to date including a first look at trending of these parameters over the early life of the instrument.

Experimental Charging Behavior of Orion UltraFlex Array Designs

NASA Technical Reports Server (NTRS)

Golofaro, Joel T.; Vayner, Boris V.; Hillard, Grover B.

2010-01-01

The present ground based investigations give the first definitive look describing the charging behavior of Orion UltraFlex arrays in both the Low Earth Orbital (LEO) and geosynchronous (GEO) environments. Note the LEO charging environment also applies to the International Space Station (ISS). The GEO charging environment includes the bounding case for all lunar mission environments. The UltraFlex photovoltaic array technology is targeted to become the sole power system for life support and on-orbit power for the manned Orion Crew Exploration Vehicle (CEV). The purpose of the experimental tests is to gain an understanding of the complex charging behavior to answer some of the basic performance and survivability issues to ascertain if a single UltraFlex array design will be able to cope with the projected worst case LEO and GEO charging environments. Stage 1 LEO plasma testing revealed that all four arrays successfully passed arc threshold bias tests down to -240 V. Stage 2 GEO electron gun charging tests revealed that only the front side area of indium tin oxide coated array designs successfully passed the arc frequency tests

A 7T spine array based on electric dipole transmitters.

PubMed

Duan, Qi; Nair, Govind; Gudino, Natalia; de Zwart, Jacco A; van Gelderen, Peter; Murphy-Boesch, Joe; Reich, Daniel S; Duyn, Jeff H; Merkle, Hellmut

2015-10-01

The goal of this study was to explore the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high fields. A two-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining eight loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared with a design using quadrature loop pairs. The radiofrequency energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies. The results indicate dramatically improved transmit efficiency for the dipole design compared with the loop excitation. A gain of up to 76% was achieved within the spinal region. For imaging of the spine, electric dipole-based transmitters provide an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high fields. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Implementation of an Antenna Array Signal Processing Breadboard for the Deep Space Network

NASA Technical Reports Server (NTRS)

Navarro, Robert

2006-01-01

The Deep Space Network Large Array will replace/augment 34 and 70 meter antenna assets. The array will mainly be used to support NASA's deep space telemetry, radio science, and navigation requirements. The array project will deploy three complexes in the western U.S., Australia, and European longitude each with 400 12m downlink antennas and a DSN central facility at JPL. THis facility will remotely conduct all real-time monitor and control for the network. Signal processing objectives include: provide a means to evaluate the performance of the Breadboard Array's antenna subsystem; design and build prototype hardware; demonstrate and evaluate proposed signal processing techniques; and gain experience with various technologies that may be used in the Large Array. Results are summarized..

A depth-of-interaction PET detector using mutual gain-equalized silicon photomultiplier

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

W. Xi, A.G, Weisenberger, H. Dong, Brian Kross, S. Lee, J. McKisson, Carl Zorn

We developed a prototype high resolution, high efficiency depth-encoding detector for PET applications based on dual-ended readout of LYSO array with two silicon photomultipliers (SiPMs). Flood images, energy resolution, and depth-of-interaction (DOI) resolution were measured for a LYSO array - 0.7 mm in crystal pitch and 10 mm in thickness - with four unpolished parallel sides. Flood images were obtained such that individual crystal element in the array is resolved. The energy resolution of the entire array was measured to be 33%, while individual crystal pixel elements utilizing the signal from both sides ranged from 23.3% to 27%. By applyingmore » a mutual-gain equalization method, a DOI resolution of 2 mm for the crystal array was obtained in the experiments while simulations indicate {approx}1 mm DOI resolution could possibly be achieved. The experimental DOI resolution can be further improved by obtaining revised detector supporting electronics with better energy resolutions. This study provides a detailed detector calibration and DOI response characterization of the dual-ended readout SiPM-based PET detectors, which will be important in the design and calibration of a PET scanner in the future.« less

Multi-Band Miniaturized Patch Antennas for a Compact, Shielded Microwave Breast Imaging Array.

PubMed

Aguilar, Suzette M; Al-Joumayly, Mudar A; Burfeindt, Matthew J; Behdad, Nader; Hagness, Susan C

2013-12-18

We present a comprehensive study of a class of multi-band miniaturized patch antennas designed for use in a 3D enclosed sensor array for microwave breast imaging. Miniaturization and multi-band operation are achieved by loading the antenna with non-radiating slots at strategic locations along the patch. This results in symmetric radiation patterns and similar radiation characteristics at all frequencies of operation. Prototypes were fabricated and tested in a biocompatible immersion medium. Excellent agreement was obtained between simulations and measurements. The trade-off between miniaturization and radiation efficiency within this class of patch antennas is explored via a numerical analysis of the effects of the location and number of slots, as well as the thickness and permittivity of the dielectric substrate, on the resonant frequencies and gain. Additionally, we compare 3D quantitative microwave breast imaging performance achieved with two different enclosed arrays of slot-loaded miniaturized patch antennas. Simulated array measurements were obtained for a 3D anatomically realistic numerical breast phantom. The reconstructed breast images generated from miniaturized patch array data suggest that, for the realistic noise power levels assumed in this study, the variations in gain observed across this class of multi-band patch antennas do not significantly impact the overall image quality. We conclude that these miniaturized antennas are promising candidates as compact array elements for shielded, multi-frequency microwave breast imaging systems.

A Flexible Nested Sodium and Proton Coil Array with Wideband Matching for Knee Cartilage MRI at 3 Tesla

PubMed Central

Brown, Ryan; Lakshmanan, Karthik; Madelin, Guillaume; Alon, Leeor; Chang, Gregory; Sodickson, Daniel K.; Regatte, Ravinder R.; Wiggins, Graham C.

2015-01-01

Purpose We describe a 6×2 channel sodium/proton array for knee MRI at 3 Tesla. Multi-element coil arrays are desirable because of well-known signal-to-noise ratio advantages over volume and single-element coils. However, low coil-tissue coupling that is characteristic of coils operating at low frequency can make the potential gains from a phased array difficult to realize. Methods The issue of low coil-tissue coupling in the developed six channel sodium receive array was addressed by implementing 1) a mechanically flexible former to minimize coil-to-tissue distance and reduce the overall diameter of the array and 2) a wideband matching scheme that counteracts preamplifier noise degradation caused by coil coupling and a high quality factor. The sodium array was complemented with a nested proton array to enable standard MRI. Results The wideband matching scheme and tight-fitting mechanical design contributed to greater than 30% central SNR gain on the sodium module over a mono-nuclear sodium birdcage coil, while the performance of the proton module was sufficient for clinical imaging. Conclusion We expect the strategies presented in this work to be generally relevant in high density receive arrays, particularly in x-nuclei or small animal applications, or in those where the array is distant from the targeted tissue. PMID:26502310

Simple Analytic Model for Nanowire Array Polarizers

NASA Astrophysics Data System (ADS)

Pelletier, Vincent; Asakawa, Koji; Wu, Mingshaw; Register, Richard; Chaikin, Paul

2006-03-01

Cylinder-forming diblock copolymers can be used to pattern nanowire arrays on a transparent substrate to be used as a polarizer, as described by Koji Asakawa in a complementary talk at this meeting. With a 33nm period, these wire arrays can polarize UV radiation, which is of great interest in lithography, astronomy and other areas. One can gain an analytical understanding of such an array made of non-perfectly conducting material of finite thickness using a model with an appropriately averaged complex dielectric function in an infinite wavelength approximation. This analysis predicts that the grid can go from an E-polarizer to an H-polarizer as the wavelength decreases below a cross-over wavelength, and experimental data confirm this cross-over. The overall response of the polarizing grid depends primarily on the plasma frequency of the metal used and the volume fraction of the nanowires, as well as the grid thickness. A numerical approach is also used to confirm the analytical model and assess departure from infinite wavelength effects. For our array dimensions, the polarization is only slightly different from this approximation for wavelengths down to 150nm.

Inelastic neutron scattering with GAINS at GELINA: An overview of the last decade

NASA Astrophysics Data System (ADS)

Borcea, Catalin; Dessagne, Philippe; Kerveno, Maëlle; Mihailescu, Cristian; Nankov, Nikolay; Negret, Alexandru; Nyman, Markus; Olacel, Adina; Oláh, Laszlo; Plompen, Arjan; Rouki, Chariklia; Rudolf, Gerard

2017-09-01

GAINS is an array of HPGe detectors installed at the GELINA neutron source of Joint Research Center, Geel, Belgium. It served to measure the cross section for (n,n'γ) reactions on many isotopes. The paper presents the experimental setup and reviews the main results obtained in the last decade

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.

Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

Functional Analysis of SPINDLY in Gibberellin Signaling in Arabidopsis1[C][W][OA

PubMed Central

Silverstone, Aron L.; Tseng, Tong-Seung; Swain, Stephen M.; Dill, Alyssa; Jeong, Sun Yong; Olszewski, Neil E.; Sun, Tai-ping

2007-01-01

The Arabidopsis (Arabidopsis thaliana) SPINDLY (SPY) protein negatively regulates the gibberellin (GA) signaling pathway. SPY is an O-linked N-acetylglucosamine (GlcNAc) transferase (OGT) with a protein-protein interaction domain consisting of 10 tetratricopeptide repeats (TPR). OGTs add a GlcNAc monosaccharide to serine/threonine residues of nuclear and cytosolic proteins. Determination of the molecular defects in 14 new spy alleles reveals that these mutations cluster in three TPRs and the C-terminal catalytic region. Phenotypic characterization of 12 spy alleles indicates that TPRs 6, 8, and 9 and the catalytic domain are crucial for GA-regulated stem elongation, floral induction, and fertility. TPRs 8 and 9 and the catalytic region are also important for modulating trichome morphology and inflorescence phyllotaxy. Consistent with a role for SPY in embryo development, several alleles affect seedling cotyledon number. These results suggest that three of the TPRs and the OGT activity in SPY are required for its function in GA signal transduction. We also examined the effect of spy mutations on another negative regulator of GA signaling, REPRESSOR OF ga1-3 (RGA). The DELLA motif in RGA is essential for GA-induced proteolysis of RGA, and deletion of this motif (as in rga-Δ17) causes a GA-insensitive dwarf phenotype. Here, we demonstrate that spy partially suppresses the rga-Δ17 phenotype but does not reduce rga-Δ17 or RGA protein levels or alter RGA nuclear localization. We propose that SPY may function as a negative regulator of GA response by increasing the activity of RGA, and presumably other DELLA proteins, by GlcNAc modification. PMID:17142481

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.

Space Power Amplification with Active Linearly Tapered Slot Antenna Array

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Lee, Richard Q.

1993-01-01

A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

Potential of minicomputer/array-processor system for nonlinear finite-element analysis

NASA Technical Reports Server (NTRS)

Strohkorb, G. A.; Noor, A. K.

1983-01-01

The potential of using a minicomputer/array-processor system for the efficient solution of large-scale, nonlinear, finite-element problems is studied. A Prime 750 is used as the host computer, and a software simulator residing on the Prime is employed to assess the performance of the Floating Point Systems AP-120B array processor. Major hardware characteristics of the system such as virtual memory and parallel and pipeline processing are reviewed, and the interplay between various hardware components is examined. Effective use of the minicomputer/array-processor system for nonlinear analysis requires the following: (1) proper selection of the computational procedure and the capability to vectorize the numerical algorithms; (2) reduction of input-output operations; and (3) overlapping host and array-processor operations. A detailed discussion is given of techniques to accomplish each of these tasks. Two benchmark problems with 1715 and 3230 degrees of freedom, respectively, are selected to measure the anticipated gain in speed obtained by using the proposed algorithms on the array processor.

Development and test of photon-counting microchannel plate detector arrays for use on space telescopes

NASA Technical Reports Server (NTRS)

Timothy, J. G.

1976-01-01

The full sensitivity, dynamic range, and photometric stability of microchannel array plates(MCP) are incorporated into a photon-counting detection system for space operations. Components of the system include feedback-free MCP's for high gain and saturated output pulse-height distribution with a stable response; multi-anode readout arrays mounted in proximity focus with the output face of the MCP; and multi-layer ceramic headers to provide electrical interface between the anode array in a sealed detector tube and the associated electronics.

Graphical User Interface for a Dual-Module EMCCD X-ray Detector Array.

PubMed

Wang, Weiyuan; Ionita, Ciprian; Kuhls-Gilcrist, Andrew; Huang, Ying; Qu, Bin; Gupta, Sandesh K; Bednarek, Daniel R; Rudin, Stephen

2011-03-16

A new Graphical User Interface (GUI) was developed using Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) for a high-resolution, high-sensitivity Solid State X-ray Image Intensifier (SSXII), which is a new x-ray detector for radiographic and fluoroscopic imaging, consisting of an array of Electron-Multiplying CCDs (EMCCDs) each having a variable on-chip electron-multiplication gain of up to 2000× to reduce the effect of readout noise. To enlarge the field-of-view (FOV), each EMCCD sensor is coupled to an x-ray phosphor through a fiberoptic taper. Two EMCCD camera modules are used in our prototype to form a computer-controlled array; however, larger arrays are under development. The new GUI provides patient registration, EMCCD module control, image acquisition, and patient image review. Images from the array are stitched into a 2k×1k pixel image that can be acquired and saved at a rate of 17 Hz (faster with pixel binning). When reviewing the patient's data, the operator can select images from the patient's directory tree listed by the GUI and cycle through the images using a slider bar. Commonly used camera parameters including exposure time, trigger mode, and individual EMCCD gain can be easily adjusted using the GUI. The GUI is designed to accommodate expansion of the EMCCD array to even larger FOVs with more modules. The high-resolution, high-sensitivity EMCCD modular-array SSXII imager with the new user-friendly GUI should enable angiographers and interventionalists to visualize smaller vessels and endovascular devices, helping them to make more accurate diagnoses and to perform more precise image-guided interventions.

Graphical user interface for a dual-module EMCCD x-ray detector array

NASA Astrophysics Data System (ADS)

Wang, Weiyuan; Ionita, Ciprian; Kuhls-Gilcrist, Andrew; Huang, Ying; Qu, Bin; Gupta, Sandesh K.; Bednarek, Daniel R.; Rudin, Stephen

2011-03-01

A new Graphical User Interface (GUI) was developed using Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) for a high-resolution, high-sensitivity Solid State X-ray Image Intensifier (SSXII), which is a new x-ray detector for radiographic and fluoroscopic imaging, consisting of an array of Electron-Multiplying CCDs (EMCCDs) each having a variable on-chip electron-multiplication gain of up to 2000x to reduce the effect of readout noise. To enlarge the field-of-view (FOV), each EMCCD sensor is coupled to an x-ray phosphor through a fiberoptic taper. Two EMCCD camera modules are used in our prototype to form a computer-controlled array; however, larger arrays are under development. The new GUI provides patient registration, EMCCD module control, image acquisition, and patient image review. Images from the array are stitched into a 2kx1k pixel image that can be acquired and saved at a rate of 17 Hz (faster with pixel binning). When reviewing the patient's data, the operator can select images from the patient's directory tree listed by the GUI and cycle through the images using a slider bar. Commonly used camera parameters including exposure time, trigger mode, and individual EMCCD gain can be easily adjusted using the GUI. The GUI is designed to accommodate expansion of the EMCCD array to even larger FOVs with more modules. The high-resolution, high-sensitivity EMCCD modular-array SSXII imager with the new user-friendly GUI should enable angiographers and interventionalists to visualize smaller vessels and endovascular devices, helping them to make more accurate diagnoses and to perform more precise image-guided interventions.

A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

Directional antenna array (DAA) for communications, control, and data link protection

NASA Astrophysics Data System (ADS)

Molchanov, Pavlo A.; Contarino, Vincent M.

2013-06-01

A next generation of Smart antennas with point-to-point communication and jam, spoof protection capability by verification of spatial position is offered. A directional antenna array (DAA) with narrow irradiation beam provides counter terrorism protection for communications, data link, control and GPS. Communications are "invisible" to guided missiles because of 20 dB smaller irradiation outside the beam and spatial separation. This solution can be implemented with current technology. Directional antennas have higher gain and can be multi-frequency or have wide frequency band in contrast to phase antenna arrays. This multi-directional antenna array provides a multi-functional communication network and simultaneously can be used for command control, data link and GPS.

Frequency control using a complex effective reflectivity in laterally coupled semiconductor laser arrays.

PubMed

Griffel, G; Marshall, W K; Gravé, I; Yariv, A; Nabiev, R

1991-08-01

Frequency selectivity of a novel type of multielement, multisection laterally coupled semiconductor laser array is studied using the round-trip method. It is found that such a structure should lead to a strong frequency selectivity owing to a periodic dependency of the threshold gain on the frequency. A gain-guided two-coupledcavity device was fabricated. The experimental results show excellent agreement with the theoretical prediction.

Report for simultaneous, multiple independently steered beam study for Airborne Electronically Steerable Phased Array (AESPA) program

NASA Technical Reports Server (NTRS)

1978-01-01

Design concepts of an array for the formation of multiple, simultaneous, independently pointed beams for satellite communication links were investigated through tradeoffs of various approaches which were conceived as possible solutions to the problem. After the preferred approach was selected, a more detailed design was configured and is presented as a candidate system that should be given further consideration for development leading to a preliminary design. This array uses an attenuator and a phase shifter with every element. The aperture excitation necessary to form the four beams is calculated and then placed across the array using these devices. Pattern analysis was performed for two beam and four beam cases with numerous patterns being presented. Parameter evaluation shown includes pointing accuracy and beam shape, sidelobe characteristics, gain control, and beam normalization. It was demonstrated that a 4 bit phase shifter and a 6 bit, 30 dB attenuator were sufficient to achieve adequate pattern performances. The phase amplitude steered multibeam array offers the flexibility of 1 to 4 beams with an increase in gain of 6 dB if only one beam is selected.

Recursive algorithms for bias and gain nonuniformity correction in infrared videos.

PubMed

Pipa, Daniel R; da Silva, Eduardo A B; Pagliari, Carla L; Diniz, Paulo S R

2012-12-01

Infrared focal-plane array (IRFPA) detectors suffer from fixed-pattern noise (FPN) that degrades image quality, which is also known as spatial nonuniformity. FPN is still a serious problem, despite recent advances in IRFPA technology. This paper proposes new scene-based correction algorithms for continuous compensation of bias and gain nonuniformity in FPA sensors. The proposed schemes use recursive least-square and affine projection techniques that jointly compensate for both the bias and gain of each image pixel, presenting rapid convergence and robustness to noise. The synthetic and real IRFPA videos experimentally show that the proposed solutions are competitive with the state-of-the-art in FPN reduction, by presenting recovered images with higher fidelity.

Effects of 1-MeV gamma radiation on a multi-anode microchannel array detector tube

NASA Technical Reports Server (NTRS)

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

1979-01-01

A multianode microchannel array (MAMA) detector tube without a photocathode was exposed to a total dose of 1,000,000 rads of 1-MeV gamma radiation from a Co-60 source. The high-voltage characteristic of the microchannel array plate, average dark count, gain, and resolution of pulse height distribution characteristics showed no degradation after this total dose. In fact, the degassing of the microchannels induced by the high radiation flux had the effect of cleaning up the array plate and improving its characteristics.

A broadband phased-array system for direct phosphorus and sodium metabolic MRI on a clinical scanner.

PubMed

Lee, R F; Giaquinto, R; Constantinides, C; Souza, S; Weiss, R G; Bottomley, P A

2000-02-01

Despite their proven gains in signal-to-noise ratio and field-of-view for routine clinical MRI, phased-array detection systems are currently unavailable for nuclei other than protons (1H). A broadband phased-array system was designed and built to convert the 1H transmitter signal to the non-1H frequency for excitation and to convert non-1H phased-array MRI signals to the 1H frequency for presentation to the narrowband 1H receivers of a clinical whole-body 1.5 T MRI system. With this system, the scanner operates at the 1H frequency, whereas phased-array MRI occurs at the frequency of the other nucleus. Pulse sequences were developed for direct phased-array sodium (23Na) and phosphorus (31P) MRI of high-energy phosphates using chemical selective imaging, thereby avoiding the complex processing and reconstruction required for phased-array magnetic resonance spectroscopy data. Flexible 4-channel 31P and 23Na phased-arrays were built and the entire system tested in phantom and human studies. The array produced a signal-to-noise ratio improvement of 20% relative to the best-positioned single coil, but gains of 300-400% were realized in many voxels located outside the effective field-of-view of the single coil. Cardiac phosphorus and sodium MRI were obtained in 6-13 min with 16 and 0.5 mL resolution, respectively. Lower resolution human cardiac 23Na MRI were obtained in as little as 4 sec. The system provides a practical approach to realizing the advantages of phased-arrays for nuclei other than 1H, and imaging metabolites directly.

Residual gas analysis for long-pulse, advanced tokamak operation.

PubMed

Klepper, C C; Hillis, D L; Bucalossi, J; Douai, D; Oddon, P; Vartanian, S; Colas, L; Manenc, L; Pégourié, B

2010-10-01

A shielded residual gas analyzer (RGA) system on Tore Supra can function during plasma operation and is set up to monitor the composition of the neutral gas in one of the pumping ducts of the toroidal pumped limited. This "diagnostic RGA" has been used in long-pulse (up to 6 min) discharges for continuous monitoring of up to 15 masses simultaneously. Comparison of the RGA-measured evolution of the H(2)/D(2) isotopic ratio in the exhaust gas to that measured by an energetic neutral particle analyzer in the plasma core provides a way to monitor the evolution of particle balance. RGA monitoring of corrective H(2) injection to maintain proper minority heating is providing a database for improved ion cyclotron resonance heating, potentially with RGA-base feedback control. In very long pulses (>4 min) absence of significant changes in the RGA-monitored, hydrocarbon particle pressures is an indication of proper operation of the actively cooled, carbon-based plasma facing components. Also H(2) could increase due to thermodesorption of overheated plasma facing components.

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

NASA Technical Reports Server (NTRS)

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

2011-01-01

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

Optimized design of Yb3+/Er3+-codoped cross-coupled integrated microring resonator arrays

NASA Astrophysics Data System (ADS)

Gǎlǎtus, Ramona; Vallés, Juan A.

2014-09-01

In this work the analytical model of the scattering response of a highly Yb3+/Er3+-codoped phosphate glass microring resonator array is developed. The microscopic statistical formalism is used to simulate its performance as a wavelengthselective amplifier. The performance of the integrated add-drop filter was investigated based on the signal transfer functions for Through and Drop ports, correlated the with gain coefficient and its dependence on pump power, signal power and Yb3+/Er3+- dopants concentration. In consequence, microring arrays with gain operating in the near infrared spectral range and, in particular, in the 1.5-mm wavelength band (emission band of Er-doped fiber amplifiers and lasers, already used in several bio/chemical sensing tasks) are highly attractive.

Microstrip Yagi array antenna for mobile satellite vehicle application

NASA Technical Reports Server (NTRS)

Huang, John; Densmore, Arthur C.

1991-01-01

A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna.

NECTAr: New electronics for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Vorobiov, S.; Bolmont, J.; Corona, P.; Delagnes, E.; Feinstein, F.; Gascón, D.; Glicenstein, J.-F.; Naumann, C. L.; Nayman, P.; Sanuy, A.; Toussenel, F.; Vincent, P.

2011-05-01

The European astroparticle physics community aims to design and build the next generation array of Imaging Atmospheric Cherenkov Telescopes (IACTs), that will benefit from the experience of the existing H.E.S.S. and MAGIC detectors, and further expand the very-high energy astronomy domain. In order to gain an order of magnitude in sensitivity in the 10 GeV to >100TeV range, the Cherenkov Telescope Array (CTA) will employ 50-100 mirrors of various sizes equipped with 1000-4000 channels per camera, to be compared with the 6000 channels of the final H.E.S.S. array. A 3-year program, started in 2009, aims to build and test a demonstrator module of a generic CTA camera. We present here the NECTAr design of front-end electronics for the CTA, adapted to the trigger and data acquisition of a large IACTs array, with simple production and maintenance. Cost and camera performances are optimized by maximizing integration of the front-end electronics (amplifiers, fast analog samplers, ADCs) in an ASIC, achieving several GS/s and a few μs readout dead-time. We present preliminary results and extrapolated performances from Monte Carlo simulations.

Domestication and Breeding of Tomatoes: What have We Gained and What Can We Gain in the Future?

PubMed Central

Bai, Yuling; Lindhout, Pim

2007-01-01

Background It has been shown that a large variation is present and exploitable from wild Solanum species but most of it is still untapped. Considering the thousands of Solanum accessions in different gene banks and probably even more that are still untouched in the Andes, it is a challenge to exploit the diversity of tomato. What have we gained from tomato domestication and breeding and what can we gain in the future? Scope This review summarizes progress on tomato domestication and breeding and current efforts in tomato genome research. Also, it points out potential challenges in exploiting tomato biodiversity and depicts future perspectives in tomato breeding with the emerging knowledge from tomato-omics. Conclusions From first domestication to modern breeding, the tomato has been continually subjected to human selection for a wide array of applications in both science and commerce. Current efforts in tomato breeding are focused on discovering and exploiting genes for the most important traits in tomato germplasm. In the future, breeders will design cultivars by a process named ‘breeding by design’ based on the combination of science and technologies from the genomic era as well as their practical skills. PMID:17717024

Enhancement of concentration range of chromatographically detectable components with array detector mass spectrometry

DOEpatents

Enke, Christie

2013-02-19

Methods and instruments for high dynamic range analysis of sample components are described. A sample is subjected to time-dependent separation, ionized, and the ions dispersed with a constant integration time across an array of detectors according to the ions m/z values. Each of the detectors in the array has a dynamically adjustable gain or a logarithmic response function, producing an instrument capable of detecting a ratio of responses or 4 or more orders of magnitude.

A 400 KHz line rate 2048 pixel modular SWIR linear array for earth observation applications

NASA Astrophysics Data System (ADS)

Anchlia, Ankur; Vinella, Rosa M.; Wouters, Kristof; Gielen, Daphne; Hooylaerts, Peter; Deroo, Pieter; Ruythooren, Wouter; van der Zanden, Koen; Vermeiren, Jan; Merken, Patrick

2015-10-01

In this paper, we report about a family of linear imaging FPAs sensitive in the [0.9 - 1.7um] band, developed for high speed applications such as LIDAR, wavelength references and OCT analyzers and also for earth observation applications. Fast linear FPAs can also be used in a wide variety of terrestrial applications, including high speed sorting, electro- and photo-luminesce and medical applications. The arrays are based on a modular ROIC design concept: modules of 512 pixels are stitched during fabrication to achieve 512, 1024 and 2048 pixel arrays. In principle, this concept can be extended to any multiple of 512 pixels, the limiting factor being the pixel yield of long InGaAs arrays and the CTE differences in the hybrid setup. Each 512-pixel module has its own on-chip digital sequencer, analog readout chain and 4 output buffers. This modular concept enables a long-linear array to run at a high line rate of 400 KHz irrespective of the array length, which limits the line rate in a traditional linear array. The pixel has a pitch of 12.5um. The detector frontend is based on CTIA (Capacitor Trans-impedance Amplifier), having 5 selectable integration capacitors giving full well from 62x103e- (gain0) to 40x106e- (gain4). An auto-zero circuit limits the detector bias non-uniformity to 5-10mV across broad intensity levels, limiting the input referred dark signal noise to 20e-rms for Tint=3ms at room temperature. An on-chip CDS that follows the CTIA facilitates removal of Reset/KTC noise, CTIA offsets and most of the 1/f noise. The measured noise of the ROIC is 35e-rms in gain0. At a master clock rate of 60MHz and a minimum integration time of 1.4us, the FPAs reach the highest line rate of 400 KHz.

Performance of the image statistics decoder in conjunction with the Goldstone-VLA array

NASA Technical Reports Server (NTRS)

Wang, H. C.; Pitt, G. H., III

1989-01-01

During Voyager's Neptune encounter, the National Radio Astronomy Observatory's Very Large Array (VLA) will be arrayed with Goldstone antennas to receive the transmitted telemetry data from the spacecraft. The telemetry signal from the VLA will drop out periodically, resulting in a periodic drop in the received signal-to-noise ratio (SNR). The Image Statistics Decoder (ISD), which assumes a correlation between pixels, can improve the bit error rate (BER) for images during these dropout periods. Simulation results have shown that the ISD, in conjunction with the Goldstone-VLA array can provide a 3-dB gain for uncompressed images at a BER of 5.0 x 10(exp -3).

Flat-plate solar array project. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Callaghan, W.; Mcdonald, R.

1986-01-01

In 1975, the U.S. Government contracted the Jet Propulsion Lab. to develop, by 1985, in conjunction with industry, the photovoltaics (PV) module and array technology required for widespread use of photovoltaics as a significant terrestrial energy source. As a result, a project that eventually became known as the Flat Plate Solar Array (FSA) Project was formed to manage an industry, university, and Government team to perform the necessary research and development. The original goals were to achieve widespread commercial use of PV modules and arrays through the development of technology that would allow them to be profitably sold for $1.07/peak watts (1985 dollars). A 10% module conversion efficiency and a 20 year lifetime were also goals. It is intended that the executive summary provide the means by which one can gain a perspective on 11 years of terrestrial photovoltaic research and development conducted by the FSA Project.

Satellite-borne active phased array techniques for mobile communications

NASA Astrophysics Data System (ADS)

Sheehan, P. G.; Forrest, J. R.

1986-07-01

This paper investigates the design of active phased arrays for communications satellites. In particular, consideration is given to the problems occurring when active arrays are required to produce multiple beams. There is a real need to keep the complexity of the array electronics to a minimum, but this conflicts with the desire to obtain the greatest possible freedom of control of the radiation pattern produced. The paper demonstrates a method of coping with the problem. Low-gain elements are used to provide design freedom and they are grouped into subarrays to limit the complexity of the rest of the system. With appropriate configurations of subarrays, greatly improved radiation pattern characteristics can be obtained and frequency reuse between multiple beams becomes feasible. A demonstration model of 108 microstrip patches grouped into 32 subarrays, operating at 12 GHz, has been constructed and verifies that the technique is effective.

New design concept of monopole antenna array for UHF 7T MRI.

PubMed

Hong, Suk-Min; Park, Joshua Haekyun; Woo, Myung-Kyun; Kim, Young-Bo; Cho, Zang-Hee

2014-05-01

We have developed and evaluated a monopole antenna array that can increase sensitivity at the center of the brain for 7T MRI applications. We have developed a monopole antenna array that has half the length of a conventional dipole antenna with eight channels for brain imaging with a 7T MRI. The eight-channel monopole antenna array and conventional eight-channel transceiver surface coil array were evaluated and compared in terms of transmit properties, specific absorption ratio (SAR), and sensitivity. The sensitivity maps were generated by dividing the SNR map by the flip angle distribution. A single surface coil provides asymmetric sensitivity resulting in reduced sensitivity at the center of the brain. In contrast, a single monopole antenna provides higher sensitivity at the center of the brain. Moreover, the monopole antenna array provides uniform sensitivity over the entire brain, and the sensitivity gain was 1.5 times higher at the center of the brain compared with the surface coil array. The monopole antenna array is a promising candidate for MRI applications, especially for brain imaging in a 7T MRI because it provides increased sensitivity at the center of the brain. Copyright © 2013 Wiley Periodicals, Inc.

Read-noise characterization of focal plane array detectors via mean-variance analysis.

PubMed

Sperline, R P; Knight, A K; Gresham, C A; Koppenaal, D W; Hieftje, G M; Denton, M B

2005-11-01

Mean-variance analysis is described as a method for characterization of the read-noise and gain of focal plane array (FPA) detectors, including charge-coupled devices (CCDs), charge-injection devices (CIDs), and complementary metal-oxide-semiconductor (CMOS) multiplexers (infrared arrays). Practical FPA detector characterization is outlined. The nondestructive readout capability available in some CIDs and FPA devices is discussed as a means for signal-to-noise ratio improvement. Derivations of the equations are fully presented to unify understanding of this method by the spectroscopic community.

An adaptive array antenna for mobile satellite communications

NASA Technical Reports Server (NTRS)

Milne, Robert

1988-01-01

The adaptive array is linearly polarized and consists essentially of a driven lambda/4 monopole surrounded by an array of parasitic elements all mounted on a ground plane of finite size. The parasitic elements are all connected to ground via pin diodes. By applying suitable bias voltages, the desired parasitic elements can be activated and made highly reflective. The directivity and pointing of the antenna beam can be controlled in both the azimuth and elevation planes using high speed digital switching techniques. The antenna RF losses are neglible and the maximum gain is close to the theoretical value determined by the effective aperture size. The antenna is compact, has a low profile, is inexpensive to manufacture and can handle high transmitter power.

PAPER: The Precision Array To Probe The Epoch Of Reionization

NASA Astrophysics Data System (ADS)

Backer, Donald C.; Parsons, A.; Bradley, R.; Parashare, C.; Gugliucci, N.; Mastrantonio, E.; Herne, D.; Lynch, M.; Wright, M.; Werhimer, D.; Carilli, C.; Datta, A.; Aguirre, J.

2007-12-01

The Precision Array to Probe the Epoch of Reionization (PAPER) is an experiment that is being designed to detect the faint HI signal from the epoch of reionization. Our instrumentation goals include: the design and building of dipole elements that are optimized for operation from 120-190 MHz with a clean beam response; amplifiers and receivers with good impedance match and overall flat gain response over a large bandpass; and an FPGA correlator capable of producing full Stokes products for the array. The array is being built and evaluated in stages at the Green Bank Observatory in West Virginia with deployment of the full instrument in Western Australia. We present results from an eight-station deployment in Green Bank and four-station deployment in Western Australia, including phase and amplitude calibration, RFI mitigation and removal, full sky maps, and wide-field snapshot imaging. We have discovered new ways to improve our system's stability and sensitivity from these early experiments, and are applying these concepts to a 16-element array in Green Bank in early 2008 and a 32-element array in Western Australia later in 2008.

A pattern recognition approach to transistor array parameter variance

NASA Astrophysics Data System (ADS)

da F. Costa, Luciano; Silva, Filipi N.; Comin, Cesar H.

2018-06-01

The properties of semiconductor devices, including bipolar junction transistors (BJTs), are known to vary substantially in terms of their parameters. In this work, an experimental approach, including pattern recognition concepts and methods such as principal component analysis (PCA) and linear discriminant analysis (LDA), was used to experimentally investigate the variation among BJTs belonging to integrated circuits known as transistor arrays. It was shown that a good deal of the devices variance can be captured using only two PCA axes. It was also verified that, though substantially small variation of parameters is observed for BJT from the same array, larger variation arises between BJTs from distinct arrays, suggesting the consideration of device characteristics in more critical analog designs. As a consequence of its supervised nature, LDA was able to provide a substantial separation of the BJT into clusters, corresponding to each transistor array. In addition, the LDA mapping into two dimensions revealed a clear relationship between the considered measurements. Interestingly, a specific mapping suggested by the PCA, involving the total harmonic distortion variation expressed in terms of the average voltage gain, yielded an even better separation between the transistor array clusters. All in all, this work yielded interesting results from both semiconductor engineering and pattern recognition perspectives.

Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

PubMed Central

Trucco, Andrea; Traverso, Federico; Crocco, Marco

2015-01-01

For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches. PMID:26066987

Monitoring the WFC3/UVIS Relative Gain with Internal Flatfields

NASA Astrophysics Data System (ADS)

Fowler, J.; Baggett, S.

2017-03-01

The WFC3/UVIS gain stability has been monitored twice yearly. This project provides a new examination of gain stability, making use of the existing internal flatfield observations taken every three days (for the Bowtie monitor) for a regular look at relative gain stability. Amplifiers are examined for consistency both in comparison to each other and over time, by normalizing the B, C, and D amplifiers to A, and then plotting statistics for each of the three normalized amplifiers with time. We find minimal trends in these statistics, with a 0.02 - 0.2% change in mean amplifier ratio over 7.5 years. The trends in the amplifiers are well-behaved with the exception of the B/A ratio, which shows increased scatter in mean, median, and standard deviation. The cause of the scatter remains unclear though we find it is not dependent upon detector defects, filter features, or shutter effects, and is only observable after pixel flagging (both from the data quality arrays and outlier values) has been applied.

A Novel Compact Wideband TSA Array for Near-Surface Ice Sheet Penetrating Radar Applications

NASA Astrophysics Data System (ADS)

Zhang, Feng; Liu, Xiaojun; Fang, Guangyou

2014-03-01

A novel compact tapered slot antenna (TSA) array for near-surface ice sheet penetrating radar applications is presented. This TSA array is composed of eight compact antenna elements which are etched on two 480mm × 283mm FR4 substrates. Each antenna element is fed by a wideband coplanar waveguide (CPW) to coupled strip-line (CPS) balun. The two antenna substrates are connected together with a metallic baffle. To obtain wideband properties, another two metallic baffles are used along broadsides of the array. This array is fed by a 1 × 8 wideband power divider. The measured S11 of the array is less than -10dB in the band of 500MHz-2GHz, and the measured gain is more than 6dBi in the whole band which agrees well with the simulated results.

Pulse-encoded ultrasound imaging of the vitreous with an annular array.

PubMed

Silverman, Ronald H; Ketterling, Jeffrey A; Mamou, Jonathan; Lloyd, Harriet O; Filoux, Erwan; Coleman, D Jackson

2012-01-01

The vitreous body is nearly transparent both optically and ultrasonically. Conventional 10- to 12-MHz diagnostic ultrasound can detect vitreous inhomogeneities at high gain settings, but has limited resolution and sensitivity, especially outside the fixed focal zone near the retina. To improve visualization of faint intravitreal fluid/gel interfaces, the authors fabricated a spherically curved 20-MHz five-element annular array ultrasound transducer, implemented a synthetic-focusing algorithm to extend the depth-of-field, and used a pulse-encoding strategy to increase sensitivity. The authors evaluated a human subject with a recent posterior vitreous detachment and compared the annular array with conventional 10-MHz ultrasound and spectral-domain optical coherence tomography. With synthetic focusing and chirp pulse-encoding, the array allowed visualization of the formed and fluid components of the vitreous with improved sensitivity and resolution compared with the conventional B-scan. Although optical coherence tomography allowed assessment of the posterior vitreoretinal interface, the ultrasound array allowed evaluation of the entire vitreous body. Copyright 2012, SLACK Incorporated.

Design of 4x1 microstrip patch antenna array for 5.8 GHz ISM band applications

NASA Astrophysics Data System (ADS)

Valjibhai, Gohil Jayesh; Bhatia, Deepak

2013-01-01

This paper describes the new design of four element antenna array using corporate feed technique. The proposed antenna array is developed on the Rogers 5880 dielectric material. The antenna array works on 5.8 GHz ISM band. The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than communications. The array antennas have VSWR < 1.6 from 5.725 - 5.875 GHz. The simulated return loss characteristic of the antenna array is - 39.3 dB at 5.8 GHz. The gain of the antenna array is 12.3 dB achieved. The directivity of the broadside radiation pattern is 12.7 dBi at the 5.8 GHz operating frequency. The antenna array is simulated using High frequency structure simulation software.

A high gain antenna system for airborne satellite communication applications

NASA Technical Reports Server (NTRS)

Maritan, M.; Borgford, M.

1990-01-01

A high gain antenna for commercial aviation satellites communication is discussed. Electromagnetic and practical design considerations as well as candidate systems implementation are presented. An evaluation of these implementation schemes is given, resulting in the selection of a simple top mounted aerodynamic phased array antenna with a remotely located beam steering unit. This concept has been developed into a popular product known as the Canadian Marconi Company CMA-2100. A description of the technical details is followed by a summary of results from the first production antennas.

Frontend Receiver Electronics for High Frequency Monolithic CMUT-on-CMOS Imaging Arrays

PubMed Central

Gurun, Gokce; Hasler, Paul; Degertekin, F. Levent

2012-01-01

This paper describes the design of CMOS receiver electronics for monolithic integration with capacitive micromachined ultrasonic transducer (CMUT) arrays for high-frequency intravascular ultrasound imaging. A custom 8-inch wafer is fabricated in a 0.35 μm two-poly, four-metal CMOS process and then CMUT arrays are built on top of the application specific integrated circuits (ASICs) on the wafer. We discuss advantages of the single-chip CMUT-on-CMOS approach in terms of receive sensitivity and SNR. Low-noise and high-gain design of a transimpedance amplifier (TIA) optimized for a forward-looking volumetric-imaging CMUT array element is discussed as a challenging design example. Amplifier gain, bandwidth, dynamic range and power consumption trade-offs are discussed in detail. With minimized parasitics provided by the CMUT-on-CMOS approach, the optimized TIA design achieves a 90 fA/√Hz input referred current noise, which is less than the thermal-mechanical noise of the CMUT element. We show successful system operation with a pulse-echo measurement. Transducer noise-dominated detection in immersion is also demonstrated through output noise spectrum measurement of the integrated system at different CMUT bias voltages. A noise figure of 1.8 dB is obtained in the designed CMUT bandwidth of 10 MHz to 20 MHz. PMID:21859585

System-Level Integrated Circuit (SLIC) Technology Development for Phased Array Antenna Applications

NASA Technical Reports Server (NTRS)

Windyka, John A.; Zablocki, Ed G.

1997-01-01

This report documents the efforts and progress in developing a 'system-level' integrated circuit, or SLIC, for application in advanced phased array antenna systems. The SLIC combines radio-frequency (RF) microelectronics, digital and analog support circuitry, and photonic interfaces into a single micro-hybrid assembly. Together, these technologies provide not only the amplitude and phase control necessary for electronic beam steering in the phased array, but also add thermally-compensated automatic gain control, health and status feedback, bias regulation, and reduced interconnect complexity. All circuitry is integrated into a compact, multilayer structure configured for use as a two-by-four element phased array module, operating at 20 Gigahertz, using a Microwave High-Density Interconnect (MHDI) process. The resultant hardware is constructed without conventional wirebonds, maintains tight inter-element spacing, and leads toward low-cost mass production. The measured performances and development issues associated with both the two-by-four element module and the constituent elements are presented. Additionally, a section of the report describes alternative architectures and applications supported by the SLIC electronics. Test results show excellent yield and performance of RF circuitry and full automatic gain control for multiple, independent channels. Digital control function, while suffering from lower manufacturing yield, also proved successful.

Remote geologic structural analysis of Yucca Flat

NASA Astrophysics Data System (ADS)

Foley, M. G.; Heasler, P. G.; Hoover, K. A.; Rynes, N. J.; Thiessen, R. L.; Alfaro, J. L.

1991-12-01

The Remote Geologic Analysis (RGA) system was developed by Pacific Northwest Laboratory (PNL) to identify crustal structures that may affect seismic wave propagation from nuclear tests. Using automated methods, the RGA system identifies all valleys in a digital elevation model (DEM), fits three-dimensional vectors to valley bottoms, and catalogs all potential fracture or fault planes defined by coplanar pairs of valley vectors. The system generates a cluster hierarchy of planar features having greater-than-random density that may represent areas of anomalous topography manifesting structural control of erosional drainage development. Because RGA uses computer methods to identify zones of hypothesized control of topography, ground truth using a well-characterized test site was critical in our evaluation of RGA's characterization of inaccessible test sites for seismic verification studies. Therefore, we applied RGA to a study area centered on Yucca Flat at the Nevada Test Site (NTS) and compared our results with both mapped geology and geologic structures and with seismic yield-magnitude models. This is the final report of PNL's RGA development project for peer review within the U.S. Department of Energy Office of Arms Control (OAC) seismic-verification community. In this report, we discuss the Yucca Flat study area, the analytical basis of the RGA system and its application to Yucca Flat, the results of the analysis, and the relation of the analytical results to known topography, geology, and geologic structures.

Robust synchronization in fiber laser arrays.

PubMed

Peles, Slaven; Rogers, Jeffrey L; Wiesenfeld, Kurt

2006-02-01

Synchronization of coupled fiber lasers has been reported in recent experiments [Bruesselbach, Opt. Lett. 30, 1339 (2005); Minden, Proc. SPIE 5335, 89 (2004)]. While these results may lead to dramatic advances in laser technology, the mechanism by which these lasers synchronize is not understood. We analyze a recently proposed [Rogers, IEEE J. Quantum Electron. 41, 767 (2005)] iterated map model of fiber laser arrays to explore this phenomenon. In particular, we look at synchronous solutions of the maps when the gain fields are constant. Determining the stability of these solutions is analytically tractable for a number of different coupling schemes. We find that in the most symmetric physical configurations the most symmetric solution is either unstable or stable over insufficient parameter range to be practical. In contrast, a lower symmetry configuration yields surprisingly robust coherence. This coherence persists beyond the pumping threshold for which the gain fields become time dependent.

A novel "gain chip" concept for high-power lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Min; Li, Mingzhong; Wang, Zhenguo; Yan, Xiongwei; Jiang, Xinying; Zheng, Jiangang; Cui, Xudong; Zhang, Xiaomin

2017-05-01

High-power lasers, including high-peak power lasers (HPPL) and high-average power lasers (HAPL), attract much interest for enormous variety of applications in inertial fusion energy (IFE), materials processing, defense, spectroscopy, and high-field physics research. To meet the requirements of high efficiency and quality, a "gain chip" concept is proposed to properly design the pumping, cooling and lasing fields. The gain chip mainly consists of the laser diode arrays, lens duct, rectangle wave guide and slab-shaped gain media. For the pumping field, the pump light will be compressed and homogenized by the lens duct to high irradiance with total internal reflection, and further coupled into the gain media through its two edge faces. For the cooling field, the coolant travels along the flow channel created by the adjacent slabs in the other two edge-face direction, and cool the lateral faces of the gain media. For the lasing field, the laser beam travels through the lateral faces and experiences minimum thermal wavefront distortions. Thereby, these three fields are in orthogonality offering more spatial freedom to handle them during the construction of the lasers. Transverse gradient doping profiles for HPPL and HAPL have been employed to achieve uniform gain distributions (UGD) within the gain media, respectively. This UGD will improve the management for both amplified spontaneous emission (ASE) and thermal behavior. Since each "gain chip" has its own pump source, power scaling can be easily achieved by placing identical "gain chips" along the laser beam axis without disturbing the gain and thermal distributions. To detail our concept, a 1-kJ pulsed amplifier is designed and optical-to-optical efficiency up to 40% has been obtained. We believe that with proper coolant (gas or liquid) and gain media (Yb:YAG, Nd:glass or Nd:YAG) our "gain chip" concept might provide a general configuration for high-power lasers with high efficiency and quality.

Loss-induced super scattering and gain-induced absorption.

PubMed

Feng, Simin

2016-01-25

Giant transmission and reflection of a finite bandwidth are demonstrated at the same wavelength when the electromagnetic wave is incident on a subwavelength array of parity-time (PT) symmetric dimers embedded in a metallic film. Remarkably, this phenomenon vanishes if the metallic substrate is lossless while keeping other parameters unchanged. Moreover super scattering can also occur when increasing the loss of the dimers while keeping the gain unchanged. When the metafilm is adjusted to the vicinity of an exceptional point, tuning either the substrate dissipation or the loss of the dimers can lead to supper scattering in stark contrast to what would be expected in conventional systems. In addition, increasing the gain of the dimers can increase the absorption near the exceptional point. These phenomena indicate that the PT-synthetic plasmonic metafilm can function as a thinfilm PT-plasmonic laser or absorber depending on the tuning parameter. One implication is that super radiation is possible from a cavity by tuning cavity dissipation or lossy element inside the cavity.

Optimum SNR data compression in hardware using an Eigencoil array.

PubMed

King, Scott B; Varosi, Steve M; Duensing, G Randy

2010-05-01

With the number of receivers available on clinical MRI systems now ranging from 8 to 32 channels, data compression methods are being explored to lessen the demands on the computer for data handling and processing. Although software-based methods of compression after reception lessen computational requirements, a hardware-based method before the receiver also reduces the number of receive channels required. An eight-channel Eigencoil array is constructed by placing a hardware radiofrequency signal combiner inline after preamplification, before the receiver system. The Eigencoil array produces signal-to-noise ratio (SNR) of an optimal reconstruction using a standard sum-of-squares reconstruction, with peripheral SNR gains of 30% over the standard array. The concept of "receiver channel reduction" or MRI data compression is demonstrated, with optimal SNR using only four channels, and with a three-channel Eigencoil, superior sum-of-squares SNR was achieved over the standard eight-channel array. A three-channel Eigencoil portion of a product neurovascular array confirms in vivo SNR performance and demonstrates parallel MRI up to R = 3. This SNR-preserving data compression method advantageously allows users of MRI systems with fewer receiver channels to achieve the SNR of higher-channel MRI systems. (c) 2010 Wiley-Liss, Inc.

Digitally Controlled Slot Coupled Patch Array

NASA Technical Reports Server (NTRS)

D'Arista, Thomas; Pauly, Jerry

2010-01-01

A four-element array conformed to a singly curved conducting surface has been demonstrated to provide 2 dB axial ratio of 14 percent, while maintaining VSWR (voltage standing wave ratio) of 2:1 and gain of 13 dBiC. The array is digitally controlled and can be scanned with the LMS Adaptive Algorithm using the power spectrum as the objective, as well as the Direction of Arrival (DoA) of the beam to set the amplitude of the power spectrum. The total height of the array above the conducting surface is 1.5 inches (3.8 cm). A uniquely configured microstrip-coupled aperture over a conducting surface produced supergain characteristics, achieving 12.5 dBiC across the 2-to-2.13- GHz and 2.2-to-2.3-GHz frequency bands. This design is optimized to retain VSWR and axial ratio across the band as well. The four elements are uniquely configured with respect to one another for performance enhancement, and the appropriate phase excitation to each element for scan can be found either by analytical beam synthesis using the genetic algorithm with the measured or simulated far field radiation pattern, or an adaptive algorithm implemented with the digitized signal. The commercially available tuners and field-programmable gate array (FPGA) boards utilized required precise phase coherent configuration control, and with custom code developed by Nokomis, Inc., were shown to be fully functional in a two-channel configuration controlled by FPGA boards. A four-channel tuner configuration and oscilloscope configuration were also demonstrated although algorithm post-processing was required.

Mechanical Design and Development of TES Bolometer Detector Arrays for the Advanced ACTPol Experiment

NASA Technical Reports Server (NTRS)

Ward, Jonathan T.; Austermann, Jason; Beall, James A.; Choi, Steve K.; Crowley, Kevin T.; Devlin, Mark J.; Duff, Shannon M.; Gallardo, Patricio M.; Henderson, Shawn W.; Ho, Shuay-Pwu Patty;

Mechanical designs and development of TES bolometer detector arrays for the Advanced ACTPol experiment

NASA Astrophysics Data System (ADS)

Ward, Jonathan T.; Austermann, Jason; Beall, James A.; Choi, Steve K.; Crowley, Kevin T.; Devlin, Mark J.; Duff, Shannon M.; Gallardo, Patricio A.; Henderson, Shawn W.; Ho, Shuay-Pwu Patty; Hilton, Gene; Hubmayr, Johannes; Khavari, Niloufar; Klein, Jeffrey; Koopman, Brian J.; Li, Dale; McMahon, Jeffrey; Mumby, Grace; Nati, Federico; Niemack, Michael D.; Page, Lyman A.; Salatino, Maria; Schillaci, Alessandro; Schmitt, Benjamin L.; Simon, Sara M.; Staggs, Suzanne T.; Thornton, Robert; Ullom, Joel N.; Vavagiakis, Eve M.; Wollack, Edward J.

2016-07-01

The next generation Advanced ACTPol (AdvACT) experiment is currently underway and will consist of four Transition Edge Sensor (TES) bolometer arrays, with three operating together, totaling 5800 detectors on the sky. Building on experience gained with the ACTPol detector arrays, AdvACT will utilize various new technologies, including 150 mm detector wafers equipped with multichroic pixels, allowing for a more densely packed focal plane. Each set of detectors includes a feedhorn array of stacked silicon wafers which form a spline profile leading to each pixel. This is then followed by a waveguide interface plate, detector wafer, back short cavity plate, and backshort cap. Each array is housed in a custom designed structure manufactured from high purity copper and then gold plated. In addition to the detector array assembly, the array package also encloses cryogenic readout electronics. We present the full mechanical design of the AdvACT high frequency (HF) detector array package along with a detailed look at the detector array stack assemblies. This experiment will also make use of extensive hardware and software previously developed for ACT, which will be modified to incorporate the new AdvACT instruments. Therefore, we discuss the integration of all AdvACT arrays with pre-existing ACTPol infrastructure.

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.

Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

NASA Technical Reports Server (NTRS)

Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

2012-01-01

Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

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.

Front-end receiver electronics for high-frequency monolithic CMUT-on-CMOS imaging arrays.

PubMed

Gurun, Gokce; Hasler, Paul; Degertekin, F

2011-08-01

This paper describes the design of CMOS receiver electronics for monolithic integration with capacitive micromachined ultrasonic transducer (CMUT) arrays for highfrequency intravascular ultrasound imaging. A custom 8-inch (20-cm) wafer is fabricated in a 0.35-μm two-poly, four-metal CMOS process and then CMUT arrays are built on top of the application specific integrated circuits (ASICs) on the wafer. We discuss advantages of the single-chip CMUT-on-CMOS approach in terms of receive sensitivity and SNR. Low-noise and high-gain design of a transimpedance amplifier (TIA) optimized for a forward-looking volumetric-imaging CMUT array element is discussed as a challenging design example. Amplifier gain, bandwidth, dynamic range, and power consumption trade-offs are discussed in detail. With minimized parasitics provided by the CMUT-on-CMOS approach, the optimized TIA design achieves a 90 fA/√Hz input-referred current noise, which is less than the thermal-mechanical noise of the CMUT element. We show successful system operation with a pulseecho measurement. Transducer-noise-dominated detection in immersion is also demonstrated through output noise spectrum measurement of the integrated system at different CMUT bias voltages. A noise figure of 1.8 dB is obtained in the designed CMUT bandwidth of 10 to 20 MHz.

Bio-Inspired Bright Structurally Colored Colloidal Amorphous Array Enhanced by Controlling Thickness and Black Background.

PubMed

Iwata, Masanori; Teshima, Midori; Seki, Takahiro; Yoshioka, Shinya; Takeoka, Yukikazu

2017-07-01

Inspired by Steller's jay, which displays angle-independent structural colors, angle-independent structurally colored materials are created, which are composed of amorphous arrays of submicrometer-sized fine spherical silica colloidal particles. When the colloidal amorphous arrays are thick, they do not appear colorful but almost white. However, the saturation of the structural color can be increased by (i) appropriately controlling the thickness of the array and (ii) placing the black background substrate. This is similar in the case of the blue feather of Steller's jay. Based on the knowledge gained through the biomimicry of structural colored materials, colloidal amorphous arrays on the surface of a black particle as the core particle are also prepared as colorful photonic pigments. Moreover, a structural color on-off system is successfully built by controlling the background brightness of the colloidal amorphous arrays. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient shutter-less non-uniformity correction method for infrared focal plane arrays

NASA Astrophysics Data System (ADS)

Huang, Xiyan; Sui, Xiubao; Zhao, Yao

2017-02-01

The non-uniformity response in infrared focal plane array (IRFPA) detectors has a bad effect on images with fixed pattern noise. At present, it is common to use shutter to prevent from radiation of target and to update the parameters of non-uniformity correction in the infrared imaging system. The use of shutter causes "freezing" image. And inevitably, there exists the problems of the instability and reliability of system, power consumption, and concealment of infrared detection. In this paper, we present an efficient shutter-less non-uniformity correction (NUC) method for infrared focal plane arrays. The infrared imaging system can use the data gaining in thermostat to calculate the incident infrared radiation by shell real-timely. And the primary output of detector except the shell radiation can be corrected by the gain coefficient. This method has been tested in real infrared imaging system, reaching high correction level, reducing fixed pattern noise, adapting wide temperature range.

A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

PubMed

Khachaturian, Mark Haig

2010-01-01

Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments

PubMed Central

Khachaturian, Mark Haig

2010-01-01

Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4–8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic). PMID:21243106

Polymer (PDMS-Fe3O4) magneto-dielectric substrate for a MIMO antenna array

NASA Astrophysics Data System (ADS)

Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Kamarudin, Muhammad Ramlee

2016-01-01

This paper presents the design of a 2 × 4 multiple-input multiple-output (MIMO) antenna array fabricated on a nanocomposite magneto-dielectric polymer substrate. The 10-nm iron oxide (Fe3O4) nanoparticles and polydimethylsiloxane (PDMS) composite is used as substrate to enhance the performance of a MIMO antenna array. The measured results showed up to 40.8 % enhancement in terms of bandwidth, 9.95 dB gain, and 57 % of radiation efficiency. Furthermore, it is found that the proposed magneto-dielectric (PDMS-Fe3O4) composite substrate provides excellent MIMO parameters such as correlation coefficient, diversity gain, and mutual coupling. The prototype of the proposed antenna is transparent, flexible, lightweight, and resistant against dust and corrosion. Measured results indicate that the proposed antenna is suitable for WLAN and ultra-wideband biomedical applications within frequency range of 5.33-7.70 GHz.

Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer

NASA Technical Reports Server (NTRS)

Little, John

2013-01-01

Advancements in common aperture antenna technology were employed to utilize its proprietary genetic algorithmbased modeling tools in an effort to develop, build, and test a dual-polarization array for Hurricane Imaging Radiometer (HIRAD) applications. Final program results demonstrate the ability to achieve a lightweight, thin, higher-gain aperture that covers the desired spectral band. NASA employs various passive microwave and millimeter-wave instruments, such as spectral radiometers, for a range of remote sensing applications, from measurements of the Earth's surface and atmosphere, to cosmic background emission. These instruments such as the HIRAD, SFMR (Stepped Frequency Microwave Radiometer), and LRR (Lightweight Rainfall Radiometer), provide unique data accumulation capabilities for observing sea surface wind, temperature, and rainfall, and significantly enhance the understanding and predictability of hurricane intensity. These microwave instruments require extremely efficient wideband or multiband antennas in order to conserve space on the airborne platform. In addition, the thickness and weight of the antenna arrays is of paramount importance in reducing platform drag, permitting greater time on station. Current sensors are often heavy, single- polarization, or limited in frequency coverage. The ideal wideband antenna will have reduced size, weight, and profile (a conformal construct) without sacrificing optimum performance. The technology applied to this new HIRAD array will allow NASA, NOAA, and other users to gather information related to hurricanes and other tropical storms more cost effectively without sacrificing sensor performance or the aircraft time on station. The results of the initial analysis and numerical design indicated strong potential for an antenna array that would satisfy all of the design requirements for a replacement HIRAD array. Multiple common aperture antenna methodologies were employed to achieve exceptional gain over the entire

Weak-signal Phase Calibration Strategies for Large DSN Arrays

NASA Technical Reports Server (NTRS)

Jones, Dayton L.

2005-01-01

The NASA Deep Space Network (DSN) is studying arrays of large numbers of small, mass-produced radio antennas as a cost-effective way to increase downlink sensitivity and data rates for future missions. An important issue for the operation of large arrays is the accuracy with which signals from hundreds of small antennas can be combined. This is particularly true at Ka band (32 GHz) where atmospheric phase variations can be large and rapidly changing. A number of algorithms exist to correct the phases of signals from individual antennas in the case where a spacecraft signal provides a useful signal-to-noise ratio (SNR) on time scales shorter than the atmospheric coherence time. However, for very weak spacecraft signals it will be necessary to rely on background natural radio sources to maintain array phasing. Very weak signals could result from a spacecraft emergency or by design, such as direct-to-Earth data transmissions from distant planetary atmospheric or surface probes using only low gain antennas. This paper considers the parameter space where external real-time phase calibration will be necessary, and what this requires in terms of array configuration and signal processing. The inherent limitations of this technique are also discussed.

Glycan array data management at Consortium for Functional Glycomics.

PubMed

Venkataraman, Maha; Sasisekharan, Ram; Raman, Rahul

2015-01-01

Glycomics or the study of structure-function relationships of complex glycans has reshaped post-genomics biology. Glycans mediate fundamental biological functions via their specific interactions with a variety of proteins. Recognizing the importance of glycomics, large-scale research initiatives such as the Consortium for Functional Glycomics (CFG) were established to address these challenges. Over the past decade, the Consortium for Functional Glycomics (CFG) has generated novel reagents and technologies for glycomics analyses, which in turn have led to generation of diverse datasets. These datasets have contributed to understanding glycan diversity and structure-function relationships at molecular (glycan-protein interactions), cellular (gene expression and glycan analysis), and whole organism (mouse phenotyping) levels. Among these analyses and datasets, screening of glycan-protein interactions on glycan array platforms has gained much prominence and has contributed to cross-disciplinary realization of the importance of glycomics in areas such as immunology, infectious diseases, cancer biomarkers, etc. This manuscript outlines methodologies for capturing data from glycan array experiments and online tools to access and visualize glycan array data implemented at the CFG.

A Novel Vacuum Packaging Design Process for Microelectromechanical System (MEMS) Quad-Mass Gyroscopes

DTIC Science & Technology

2016-09-01

16 2.2.1 Bake Out 18 2.2.2 Ramp-Up 19 2.2.3 Lid Seal 20 2.2.4 Cool/Purge 22 2.3 Residual Gas Analyzer Experiment 23 3. Results 28 4...Fig. 24 RGA experiment setup .........................................................................24 Fig. 25 RGA output for a 1-h bake out at T...225 °C ......................................25 Fig. 26 RGA output of a 2-h sample for an 8-h bake out .................................26 Fig. 27

Adaptive antenna arrays for weak interfering signals

NASA Technical Reports Server (NTRS)

Gupta, I. J.

1985-01-01

The interference protection provided by adaptive antenna arrays to an Earth station or satellite receive antenna system is studied. The case where the interference is caused by the transmission from adjacent satellites or Earth stations whose signals inadverently enter the receiving system and interfere with the communication link is considered. Thus, the interfering signals are very weak. To increase the interference suppression, one can either decrease the thermal noise in the feedback loops or increase the gain of the auxiliary antennas in the interfering signal direction. Both methods are examined. It is shown that one may have to reduce the noise correlation to impractically low values and if directive auxiliary antennas are used, the auxiliary antenna size may have to be too large. One can, however, combine the two methods to achieve the specified interference suppression with reasonable requirements of noise decorrelation and auxiliary antenna size. Effects of the errors in the steering vector on the adaptive array performance are studied.

The Potential of Phased Arrays for Planetary Exploration

NASA Astrophysics Data System (ADS)

Pogorzelski, Ronald J.

2000-01-01

Phased array antennas provide a set of operational capabilities which are very attractive for certain mission applications and not very attractive for others. Such antennas are by no means a panacea for telecommunications. In this paper the features of phased arrays are reviewed and their implications for space missions are considered in terms of benefits and costs. The primary capability provided by a phased array is electronic beam agility. The beam direction may be controlled at electronic speeds (vs. mechanical actuation) permitting time division multiplexing of multiple "users." Moreover, the beam direction can be varied over a full hemisphere (for a planar array). On the other hand, such antennas are typically much more complicated than the more commonly used reflectors and horns and this implies higher cost. In some applications, this increased cost must be accepted if the mission is to be carried out at all. The SIR-C radar is an example of such a case albeit not for deep space. Assuming for the sake of argument that the complexity and cost of a phased array can be significantly reduced, where can such antennas be of value in the future of planetary exploration? Potential applications to be discussed are planetary rovers, landers, and orbiters including both the areosynchronous and low orbit varieties. In addition, consideration is given to links from deep space to earth. As may be fairly obvious, the deep space link to earth would not benefit from the wide angle steering capability provided by a phase array whereas a rover could gain advantage from the capability to steer a beam anywhere in the sky. In the rover case, however, physical size of the aperture becomes a significant factor which, of course, has implications regarding the choice of frequency band. Recent research work concerning phased arrays has suggested that future phased arrays might be made less complex and, therefore, less costly. Successful realization of such phased arrays would enable

Gain of GRHL2 is associated with early recurrence of hepatocellular carcinoma.

PubMed

Tanaka, Yasuo; Kanai, Fumihiko; Tada, Motohisa; Tateishi, Ryosuke; Sanada, Masashi; Nannya, Yasuhito; Ohta, Miki; Asaoka, Yoshinari; Seto, Motoko; Shiina, Shuichiro; Yoshida, Haruhiko; Kawabe, Takao; Yokosuka, Osamu; Ogawa, Seishi; Omata, Masao

2008-11-01

The aim of this study is to identify genomic changes that might be implicated in hepatocellular carcinoma (HCC) progression, and evaluate the associations with clinico-pathological features. The genomic DNA of 17 hepatoma cell lines was analyzed using Affymetrix GeneChip Human Mapping 50K high-density oligonucleotide arrays. We selected representative genes from recurrent amplified regions and measured the copy number of these genes in 70 HCC clinical samples. We found 10 recurrent high-grade gain regions spanning less than 3 Mb in at least two hepatoma cell lines, and selected 10 representative genes. The copy number was almost normal in non-cancerous tissue and frequently amplified in Edmondson grade II or III HCC compared to Edmondson grade I HCC. Gain of TAX1BP1 in 7p15.2-1 was associated with larger tumor size and positivity of HCV antibody, and gain of CCND1 in 11q13.2-3 was associated with larger tumor size by multivariate analysis. Furthermore, a gain of GRHL2 in 8q22.3 was associated with early recurrence of HCC, controlling for clinical parameters. Decreased GRHL2 expression by RNA interference inhibits the growth of hepatoma cells, suggesting its association with cell proliferation. A gain of GRHL2 might be a predictive marker for HCC recurrence.

Ultra-broad gain quantum cascade lasers tunable from 6.5 to 10.4 μm.

PubMed

Xie, Feng; Caneau, C; Leblanc, H; Ho, M-T; Zah, C

2015-09-01

We present a quantum cascade laser structure with an ultra-broad gain profile that covers the wavelength range from 6.5 to 10.4 μm. In a grating-tuned external cavity, we demonstrated continuous tuning from 1027  cm(-1) to 1492  cm(-1) with this broad gain laser chip. We also fabricated distributed feedback quantum cascade laser arrays with this active region design and varied grating periods. We demonstrated single wavelength lasing from 962 (10.4) to 1542  cm(-1) (6.5 μm). The frequency coverage (580  cm(-1)) is about 46% of center frequency.

Dynamic characteristics of far-field radiation of current modulated phase-locked diode laser arrays

NASA Technical Reports Server (NTRS)

Elliott, R. A.; Hartnett, K.

1987-01-01

A versatile and powerful streak camera/frame grabber system for studying the evolution of the near and far field radiation patterns of diode lasers was assembled and tested. Software needed to analyze and display the data acquired with the steak camera/frame grabber system was written and the total package used to record and perform preliminary analyses on the behavior of two types of laser, a ten emitter gain guided array and a flared waveguide Y-coupled array. Examples of the information which can be gathered with this system are presented.

Microwave beamed power technology improvement. [magnetrons and slotted waveguide arrays

NASA Technical Reports Server (NTRS)

Brown, W. C.

1980-01-01

The magnetron directional amplifier was tested for (1) phase shift and power output as a function of gain, anode current, and anode voltage, (2) background noise and harmonics in the output, (3) long life potential of the magnetron cathode, and (4) high operational efficiency. Examples of results were an adequate range of current and voltage over which 20 dB of amplification could be obtained, spectral noise density 155 dB below the carrier, 81.7% overall efficiency, and potential cathode life of 50 years in a design for solar power satellite use. A fabrication method was used to fabricate a 64 slot, 30 in square slotted waveguide array module from 0.020 in thick aluminum sheet. The test results on the array are discussed.

32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

PubMed

Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

2006-07-01

A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

Detector arrays for photometric measurements at soft X-ray, ultraviolet and visible wavelengths

NASA Technical Reports Server (NTRS)

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

1979-01-01

The construction and modes of operation of the Multi-Anode Microchannel Array (MAMA) detectors are described, and the designs of spectrometers utilizing them are outlined. MAMA consists of a curved microchannel array plate, an opaque photocathode (peak quantum efficiency of 19% at 1216 A), and a multi-anode (either discrete- or coincidence-anode) readout array. Designed for use in instruments on spaceborne telescopes, MAMA can be operated in a windowless configuration in extreme-ultraviolet and soft X-ray wavelengths, or in a sealed configuration at UV and visible wavelengths. Advantages of MAMA include low applied potential (less than 3.0 kV), high gain (greater than 10 to the 6th electrons/pulse), low sensitivity to high-energy charged particles, and immunity to external magnetic fields of less than 500 Gauss

New customizable phased array UT instrument opens door for furthering research and better industrial implementation

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

Dao, Gavin; Ginzel, Robert

2014-02-18

Phased array UT as an inspection technique in itself continues to gain wide acceptance. However, there is much room for improvement in terms of implementation of Phased Array (PA) technology for every unique NDT application across several industries (e.g. oil and petroleum, nuclear and power generation, steel manufacturing, etc.). Having full control of the phased array instrument and customizing a software solution is necessary for more seamless and efficient inspections, from setting the PA parameters, collecting data and reporting, to the final analysis. NDT researchers and academics also need a flexible and open platform to be able to control variousmore » aspects of the phased array process. A high performance instrument with advanced PA features, faster data rates, a smaller form factor, and capability to adapt to specific applications, will be discussed.« less

Printed Antenna Array with Flat-Top Radiation Pattern

NASA Astrophysics Data System (ADS)

Milijić, Marija R.; Nešić, Aleksandar D.; Milovanović, Bratislav D.; Nešić, Dušan A.

2018-04-01

A printed antenna array consisting of 10 wideband symmetrical pentagonal dipoles is presented. The feed network of impedance transformers is employed to provide appropriate amplitude and phase distribution necessary to obtain flat top beam pattern. The measured results demonstrate excellent radiation characteristics including 38° flat gain region with maximum ripple of 3.5 dB at the centre frequency. Furthermore, the proposed antenna that is placed in corner reflector with angle of 60° has good gain (17 dBi) and side lobe suppression (18.9 dB). Although it is designed at the centre frequency fc=12 GHz, it was shown to be capable of shaping a good flat top radiation pattern within a fractional bandwidth at least 6 % of centre frequency. Also, proposed antenna features cheap, simple and easy fabrication that makes it suitable for mass production.

Structural-electrical coupling optimisation for radiating and scattering performances of active phased array antenna

NASA Astrophysics Data System (ADS)

Wang, Congsi; Wang, Yan; Wang, Zhihai; Wang, Meng; Yuan, Shuai; Wang, Weifeng

2018-04-01

It is well known that calculating and reducing of radar cross section (RCS) of the active phased array antenna (APAA) are both difficult and complicated. It remains unresolved to balance the performance of the radiating and scattering when the RCS is reduced. Therefore, this paper develops a structure and scattering array factor coupling model of APAA based on the phase errors of radiated elements generated by structural distortion and installation error of the array. To obtain the optimal radiating and scattering performance, an integrated optimisation model is built to optimise the installation height of all the radiated elements in normal direction of the array, in which the particle swarm optimisation method is adopted and the gain loss and scattering array factor are selected as the fitness function. The simulation indicates that the proposed coupling model and integrated optimisation method can effectively decrease the RCS and that the necessary radiating performance can be simultaneously guaranteed, which demonstrate an important application value in engineering design and structural evaluation of APAA.

On the optimization of a mixed speaker array in an enclosed space using the virtual-speaker weighting method

NASA Astrophysics Data System (ADS)

Peng, Bo; Zheng, Sifa; Liao, Xiangning; Lian, Xiaomin

2018-03-01

In order to achieve sound field reproduction in a wide frequency band, multiple-type speakers are used. The reproduction accuracy is not only affected by the signals sent to the speakers, but also depends on the position and the number of each type of speaker. The method of optimizing a mixed speaker array is investigated in this paper. A virtual-speaker weighting method is proposed to optimize both the position and the number of each type of speaker. In this method, a virtual-speaker model is proposed to quantify the increment of controllability of the speaker array when the speaker number increases. While optimizing a mixed speaker array, the gain of the virtual-speaker transfer function is used to determine the priority orders of the candidate speaker positions, which optimizes the position of each type of speaker. Then the relative gain of the virtual-speaker transfer function is used to determine whether the speakers are redundant, which optimizes the number of each type of speaker. Finally the virtual-speaker weighting method is verified by reproduction experiments of the interior sound field in a passenger car. The results validate that the optimum mixed speaker array can be obtained using the proposed method.

Optimum sensor placement for microphone arrays

NASA Astrophysics Data System (ADS)

Rabinkin, Daniel V.

Microphone arrays can be used for high-quality sound pickup in reverberant and noisy environments. Sound capture using conventional single microphone methods suffers severe degradation under these conditions. The beamforming capabilities of microphone array systems allow highly directional sound capture, providing enhanced signal-to-noise ratio (SNR) when compared to single microphone performance. The overall performance of an array system is governed by its ability to locate and track sound sources and its ability to capture sound from desired spatial volumes. These abilities are strongly affected by the spatial placement of microphone sensors. A method is needed to optimize placement for a specified number of sensors in a given acoustical environment. The objective of the optimization is to obtain the greatest average system SNR for sound capture in the region of interest. A two-step sound source location method is presented. In the first step, time delay of arrival (TDOA) estimates for select microphone pairs are determined using a modified version of the Omologo-Svaizer cross-power spectrum phase expression. In the second step, the TDOA estimates are used in a least-mean-squares gradient descent search algorithm to obtain a location estimate. Statistics for TDOA estimate error as a function of microphone pair/sound source geometry and acoustic environment are gathered from a set of experiments. These statistics are used to model position estimation accuracy for a given array geometry. The effectiveness of sound source capture is also dependent on array geometry and the acoustical environment. Simple beamforming and time delay compensation (TDC) methods provide spatial selectivity but suffer performance degradation in reverberant environments. Matched filter array (MFA) processing can mitigate the effects of reverberation. The shape and gain advantage of the capture region for these techniques is described and shown to be highly influenced by the placement of

Facile fabrication of super-hydrophobic nano-needle arrays via breath figures method.

PubMed

Kim, Jiseok; Lew, Brian; Kim, Woo Soo

2011-12-06

Super-hydrophobic surfaces which have been fabricated by various methods such as photolithography, chemical treatment, self-assembly, and imprinting have gained enormous attention in recent years. Especially 2D arrays of nano-needles have been shown to have super-hydrophobicity due to their sharp surface roughness. These arrays can be easily generated by removing the top portion of the honeycomb films prepared by the breath figures method. The hydrophilic block of an amphiphilic polymer helps in the fabrication of the nano-needle arrays through the production of well-ordered honeycomb films and good adhesion of the film to a substrate. Anisotropic patterns with water wettability difference can be useful for patterning cells and other materials using their selective growth on the hydrophilic part of the pattern. However, there has not been a simple way to generate patterns with highly different wettability. Mechanical stamping of the nano-needle array with a polyurethane stamp might be the simplest way to fabricate patterns with wettability difference. In this study, super-hydrophobic nano-needle arrays were simply fabricated by removing the top portion of the honeycomb films. The maximum water contact angle obtained with the nano-needle array was 150°. By controlling the pore size and the density of the honeycomb films, the height, width, and density of nano-needle arrays were determined. Anisotropic patterns with different wettability were fabricated by simply pressing the nano-needle array at ambient temperature with polyurethane stamps which were flexible but tough. Mechanical stamping of nano-needle arrays with micron patterns produced hierarchical super-hydrophobic structures.PACS: 05.70.Np, 68.55.am, 68.55.jm.

Facile fabrication of super-hydrophobic nano-needle arrays via breath figures method

PubMed Central

2011-01-01

Super-hydrophobic surfaces which have been fabricated by various methods such as photolithography, chemical treatment, self-assembly, and imprinting have gained enormous attention in recent years. Especially 2D arrays of nano-needles have been shown to have super-hydrophobicity due to their sharp surface roughness. These arrays can be easily generated by removing the top portion of the honeycomb films prepared by the breath figures method. The hydrophilic block of an amphiphilic polymer helps in the fabrication of the nano-needle arrays through the production of well-ordered honeycomb films and good adhesion of the film to a substrate. Anisotropic patterns with water wettability difference can be useful for patterning cells and other materials using their selective growth on the hydrophilic part of the pattern. However, there has not been a simple way to generate patterns with highly different wettability. Mechanical stamping of the nano-needle array with a polyurethane stamp might be the simplest way to fabricate patterns with wettability difference. In this study, super-hydrophobic nano-needle arrays were simply fabricated by removing the top portion of the honeycomb films. The maximum water contact angle obtained with the nano-needle array was 150°. By controlling the pore size and the density of the honeycomb films, the height, width, and density of nano-needle arrays were determined. Anisotropic patterns with different wettability were fabricated by simply pressing the nano-needle array at ambient temperature with polyurethane stamps which were flexible but tough. Mechanical stamping of nano-needle arrays with micron patterns produced hierarchical super-hydrophobic structures. PACS: 05.70.Np, 68.55.am, 68.55.jm PMID:22145673

ArrayBridge: Interweaving declarative array processing with high-performance computing

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

Xing, Haoyuan; Floratos, Sofoklis; Blanas, Spyros

Scientists are increasingly turning to datacenter-scale computers to produce and analyze massive arrays. Despite decades of database research that extols the virtues of declarative query processing, scientists still write, debug and parallelize imperative HPC kernels even for the most mundane queries. This impedance mismatch has been partly attributed to the cumbersome data loading process; in response, the database community has proposed in situ mechanisms to access data in scientific file formats. Scientists, however, desire more than a passive access method that reads arrays from files. This paper describes ArrayBridge, a bi-directional array view mechanism for scientific file formats, that aimsmore » to make declarative array manipulations interoperable with imperative file-centric analyses. Our prototype implementation of ArrayBridge uses HDF5 as the underlying array storage library and seamlessly integrates into the SciDB open-source array database system. In addition to fast querying over external array objects, ArrayBridge produces arrays in the HDF5 file format just as easily as it can read from it. ArrayBridge also supports time travel queries from imperative kernels through the unmodified HDF5 API, and automatically deduplicates between array versions for space efficiency. Our extensive performance evaluation in NERSC, a large-scale scientific computing facility, shows that ArrayBridge exhibits statistically indistinguishable performance and I/O scalability to the native SciDB storage engine.« less

Low-Gain Circularly Polarized Antenna with Torus-Shaped Pattern

NASA Technical Reports Server (NTRS)

Amaro, Luis R.; Kruid, Ronald C.; Vacchione, Joseph D.; Prata, Aluizio

2012-01-01

The Juno mission to Jupiter requires an antenna with a torus-shaped antenna pattern with approximately 6 dBic gain and circular polarization over the Deep Space Network (DSN) 7-GHz transmit frequency and the 8-GHz receive frequency. Given the large distances that accumulate en-route to Jupiter and the limited power afforded by the solar-powered vehicle, this toroidal low-gain antenna requires as much gain as possible while maintaining a beam width that could facilitate a +/-10deg edge of coverage. The natural antenna that produces a toroidal antenna pattern is the dipole, but the limited approx. = 2.2 dB peak gain would be insufficient. Here a shaped variation of the standard bicone antenna is proposed that could achieve the required gains and bandwidths while maintaining a size that was not excessive. The final geometry that was settled on consisted of a corrugated, shaped bicone, which is fed by a WR112 waveguide-to-coaxial- waveguide transition. This toroidal low-gain antenna (TLGA) geometry produced the requisite gain, moderate sidelobes, and the torus-shaped antenna pattern while maintaining a very good match over the entire required frequency range. Its "horn" geometry is also low-loss and capable of handling higher powers with large margins against multipactor breakdown. The final requirement for the antenna was to link with the DSN with circular polarization. A four-layer meander-line array polarizer was implemented; an approach that was fairly well suited to the TLGA geometry. The principal development of this work was to adapt the standard linear bicone such that its aperture could be increased in order to increase the available gain of the antenna. As one increases the aperture of a standard bicone, the phase variation across the aperture begins to increase, so the larger the aperture becomes, the greater the phase variation. In order to maximize the gain from any aperture antenna, the phase should be kept as uniform as possible. Thus, as the standard

Low Cost Beam-Steering Approach for a Series-Fed Array

NASA Technical Reports Server (NTRS)

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

2013-01-01

Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex and costly. This paper presents a concept which overcomes these detrimental attributes by eliminating all of the phased array backend (including phase shifters). Instead, a propagation constant reconfigurable transmission line in a series fed array arrangement is used to allow phase shifting with one small (less than or equal to 100mil) linear mechanical motion. A novel slotted coplanar stripline design improves on previous transmission lines by demonstrating a greater control of propagation constant, thus allowing practical prototypes to be built. Also, beam steering pattern control is explored. We show that with correct choice of line impedance, pattern control is possible for all scan angles. A 20 element array scanning from -25 deg less than or equal to theta less than or equal to 21 deg. with mostly uniform gain at 13GHz is presented. Measured patterns show a reduced scan range of 12 deg. less than or equal to theta less than or equal to 25 deg. due to a correctable manufacturing error as verified by simulation. Beam squint is measured to be plus or minus 2.5 deg for a 600MHz bandwidth and cross-pol is measured to be at least -15dB.

Exploring the performance of large-N radio astronomical arrays

NASA Astrophysics Data System (ADS)

Lonsdale, Colin J.; Doeleman, Sheperd S.; Cappallo, Roger J.; Hewitt, Jacqueline N.; Whitney, Alan R.

2000-07-01

New radio telescope arrays are currently being contemplated which may be built using hundreds, or even thousands, of relatively small antennas. These include the One Hectare Telescope of the SETI Institute and UC Berkeley, the LOFAR telescope planned for the New Mexico desert surrounding the VLA, and possibly the ambitious international Square Kilometer Array (SKA) project. Recent and continuing advances in signal transmission and processing technology make it realistic to consider full cross-correlation of signals from such a large number of antennas, permitting the synthesis of an aperture with much greater fidelity than in the past. In principle, many advantages in instrumental performance are gained by this 'large-N' approach to the design, most of which require the development of new algorithms. Because new instruments of this type are expected to outstrip the performance of current instruments by wide margins, much of their scientific productivity is likely to come from the study of objects which are currently unknown. For this reason, instrumental flexibility is of special importance in design studies. A research effort has begun at Haystack Observatory to explore large-N performance benefits, and to determine what array design properties and data reduction algorithms are required to achieve them. The approach to these problems, involving a sophisticated data simulator, algorithm development, and exploration of array configuration parameter space, will be described, and progress to date will be summarized.

Thermal management of quantum cascade lasers in an individually addressable monolithic array architecture

NASA Astrophysics Data System (ADS)

Missaggia, Leo; Wang, Christine; Connors, Michael; Saar, Brian; Sanchez-Rubio, Antonio; Creedon, Kevin; Turner, George; Herzog, William

2016-03-01

There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9μm.

Correlating Nanoscopic Energy Transfer and Far-Field Emission to Unravel Lasing Dynamics in Plasmonic Nanocavity Arrays

DOE PAGES

Deeb, Claire; Guo, Zhi; Yang, Ankun; ...

2018-01-25

Excited-state interactions between nanoscale cavities and photoactive molecules are critical in plasmonic nanolasing, although the underlying details are less-resolved. This paper reports direct visualization of the energy-transfer dynamics between two-dimensional arrays of plasmonic gold bowtie nanocavities and dye molecules. Transient absorption microscopy measurements of single bowties within the array surrounded by gain molecules showed fast excited-state quenching (2.6 ± 1 ps) characteristic of individual nanocavities. Upon optical pumping at powers above threshold, lasing action emerged depending on the spacing of the array. By correlating ultrafast microscopy and far-field light emission characteristics, we found that bowtie nanoparticles acted as isolated cavitiesmore » when the diffractive modes of the array did not couple to the plasmonic gap mode. These results demonstrate how ultrafast microscopy can provide insight into energy relaxation pathways and, specifically, how nanocavities in arrays can show single-unit nanolaser properties.« less

Correlating Nanoscopic Energy Transfer and Far-Field Emission to Unravel Lasing Dynamics in Plasmonic Nanocavity Arrays

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

Deeb, Claire; Guo, Zhi; Yang, Ankun

Excited-state interactions between nanoscale cavities and photoactive molecules are critical in plasmonic nanolasing, although the underlying details are less-resolved. This paper reports direct visualization of the energy-transfer dynamics between two-dimensional arrays of plasmonic gold bowtie nanocavities and dye molecules. Transient absorption microscopy measurements of single bowties within the array surrounded by gain molecules showed fast excited-state quenching (2.6 ± 1 ps) characteristic of individual nanocavities. Upon optical pumping at powers above threshold, lasing action emerged depending on the spacing of the array. By correlating ultrafast microscopy and far-field light emission characteristics, we found that bowtie nanoparticles acted as isolated cavitiesmore » when the diffractive modes of the array did not couple to the plasmonic gap mode. These results demonstrate how ultrafast microscopy can provide insight into energy relaxation pathways and, specifically, how nanocavities in arrays can show single-unit nanolaser properties.« less

Impact of LDEF photovoltaic experiment findings upon spacecraft solar array design and development requirements

NASA Technical Reports Server (NTRS)

Young, Leighton E.

1993-01-01

Photovoltaic cells (solar cells) and other solar array materials were flown in a variety of locations on the Long Duration Exposure Facility (LDEF). With respect to the predicted leading edge, solar array experiments were located at 0 degrees (row 9), 30 degrees (row 8) and 180 degrees (row 3). Postflight estimates of location of the experiments with respect to the velocity vector add 8.1 degrees to these values. Experiments were also located on the Earth end of the LDEF longitudinal axis. Types and magnitudes of detrimental effects differ between the locations with some commonality. Postflight evaluation of the solar array experiments reveal that some components/materials are very resistant to the environment to which they were exposed while others need protection, modification, or replacement. Interaction of materials with atomic oxygen (AO), as an area of major importance, was dramatically demonstrated by LDEF results. Information gained from the LDEF flight allows array developers to set new requirements for on-going and future technology and flight component development.

The conical conformal MEMS quasi-end-fire array antenna

NASA Astrophysics Data System (ADS)

Cong, Lin; Xu, Lixin; Li, Jianhua; Wang, Ting; Han, Qi

2017-03-01

The microelectromechanical system (MEMS) quasi-end-fire array antenna based on a liquid crystal polymer (LCP) substrate is designed and fabricated in this paper. The maximum radiation direction of the antenna tends to the cone axis forming an angle less than 90∘, which satisfies the proximity detection system applied at the forward target detection. Furthermore, the proposed antenna is fed at the ended side in order to save internal space. Moreover, the proposed antenna takes small covering area of the proximity detection system. The proposed antenna is fabricated by using the flexible MEMS process, and the measurement results agree well with the simulation results. This is the first time that a conical conformal array antenna is fabricated by the flexible MEMS process to realize the quasi-end-fire radiation. A pair of conformal MEMS array antennas resonates at 14.2 GHz with its mainlobes tending to the cone axis forming a 30∘ angle and a 31∘ angle separately, and the gains achieved are 1.82 dB in two directions, respectively. The proposed antenna meets the performance requirements for the proximity detection system which has vast application prospects.

Microphone Array

NASA Astrophysics Data System (ADS)

Bader, Rolf

This chapter deals with microphone arrays. It is arranged according to the different methods available to proceed through the different problems and through the different mathematical methods. After discussing general properties of different array types, such as plane arrays, spherical arrays, or scanning arrays, it proceeds to the signal processing tools that are most used in speech processing. In the third section, backpropagating methods based on the Helmholtz-Kirchhoff integral are discussed, which result in spatial radiation patterns of vibrating bodies or air.

Digital equalization of time-delay array receivers on coherent laser communications.

PubMed

Belmonte, Aniceto

2017-01-15

Field conjugation arrays use adaptive combining techniques on multi-aperture receivers to improve the performance of coherent laser communication links by mitigating the consequences of atmospheric turbulence on the down-converted coherent power. However, this motivates the use of complex receivers as optical signals collected by different apertures need to be adaptively processed, co-phased, and scaled before they are combined. Here, we show that multiple apertures, coupled with optical delay lines, combine retarded versions of a signal at a single coherent receiver, which uses digital equalization to obtain diversity gain against atmospheric fading. We found in our analysis that, instead of field conjugation arrays, digital equalization of time-delay multi-aperture receivers is a simpler and more versatile approach to accomplish reduction of atmospheric fading.

How coupling affects closely packed rectenna arrays used for wireless power transmission

NASA Astrophysics Data System (ADS)

Walls, Deidra; Choi, Sang H.; Yoon, Hargsoon; Geddis, Demetris; Song, Kyo D.

2017-04-01

The development of power transmission by microwave beam power harvesting attracts manufactures for use of wireless power transmission. Optimizing maximum conversion efficiency is affected by many design parameters, and has been mainly focused previously. Combining several rectennas in one array potentially aides in the amount of microwave energy that can be harvested for energy conversion. Closely packed rectenna arrays is the result of the demand to minimize size and weight for flexibility. This paper specifically focuses on the coupling effects on power; mutual coupling, comparing sparameters and gain total while varying effective parameters. This paper investigates how coupling between each dipole positively and negatively affects the microwave energy, harvesting, and the design limitations.

A small hemispherical helical antenna array for two-dimensional GPS beam-forming

NASA Astrophysics Data System (ADS)

Hui, H. T.; Aditya, S.; Mohamed, F. Bin S.; Hafiedz-Ul, A. Bin T.

2005-02-01

A small hemispherical helical antenna array with multibeam output for GPS beam-forming is designed and characterized. A Butler matrix beam-forming network is designed to provide four spatial beams in a two-dimensional directional space. The original design of the hemispherical helical antenna elements is modified in order to match it to the system impedance. Our study shows that even after an ˜30° scan from the normal direction, the maximum change in beam width is only 6°, the maximum change in axial ratio is 1.4 dB, and the maximum change in power gain is 1.1 dB. These characteristics indicate that the array can be potentially used for GPS beam-forming.

Automated measurement of respiratory gas exchange by an inert gas dilution technique

NASA Technical Reports Server (NTRS)

Sawin, C. F.; Rummel, J. A.; Michel, E. L.

1974-01-01

A respiratory gas analyzer (RGA) has been developed wherein a mass spectrometer is the sole transducer required for measurement of respiratory gas exchange. The mass spectrometer maintains all signals in absolute phase relationships, precluding the need to synchronize flow and gas composition as required in other systems. The RGA system was evaluated by comparison with the Douglas bag technique. The RGA system established the feasibility of the inert gas dilution method for measuring breath-by-breath respiratory gas exchange. This breath-by-breath analytical capability permits detailed study of transient respiratory responses to exercise.

Method of steering the gain of a multiple antenna global positioning system receiver

NASA Astrophysics Data System (ADS)

Evans, Alan G.; Hermann, Bruce R.

1992-06-01

A method for steering the gain of a multiple antenna Global Positioning System (GPS) receiver toward a plurality of a GPS satellites simultaneously is provided. The GPS signals of a known wavelength are processed digitally for a particular instant in time. A range difference or propagation delay between each antenna for GPS signals received from each satellite is first resolved. The range difference consists of a fractional wavelength difference and an integer wavelength difference. The fractional wavelength difference is determined by each antenna's tracking loop. The integer wavelength difference is based upon the known wavelength and separation between each antenna with respect to each satellite position. The range difference is then used to digitally delay the GPS signals at each antenna with respect to a reference antenna. The signal at the reference antenna is then summed with the digitally delayed signals to generate a composite antenna gain. The method searches for the correct number of integer wavelengths to maximize the composite gain. The range differences are also used to determine the attitude of the array.

Magnetic arrays

DOEpatents

Trumper, David L.; Kim, Won-jong; Williams, Mark E.

1997-05-20

Electromagnet arrays which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness.

Feed system design and experimental results in the uhf model study for the proposed Urbana phased array

NASA Technical Reports Server (NTRS)

Loane, J. T.; Bowhill, S. A.; Mayes, P. E.

1982-01-01

The effects of atmospheric turbulence and the basis for the coherent scatter radar techniques are discussed. The reasons are given for upgrading the Radar system to a larger steerable array. Phase array theory pertinent to the system design is reviewed, along with approximations for maximum directive gain and blind angles due to mutual coupling. The methods and construction techniques employed in the UHF model study are explained. The antenna range is described, with a block diagram for the mode of operation used.

Using a coherent hydrophone array for observing sperm whale range, classification, and shallow-water dive profiles.

PubMed

Tran, Duong D; Huang, Wei; Bohn, Alexander C; Wang, Delin; Gong, Zheng; Makris, Nicholas C; Ratilal, Purnima

2014-06-01

Sperm whales in the New England continental shelf and slope were passively localized, in both range and bearing, and classified using a single low-frequency (<2500 Hz), densely sampled, towed horizontal coherent hydrophone array system. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. Multiple concurrently vocalizing sperm whales, in the far-field of the horizontal receiver array, were distinguished and classified based on their horizontal spatial locations and the inter-pulse intervals of their vocalized click signals. The dive profile was estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth located close to the array's near-field where depth estimation was feasible by employing time difference of arrival of the direct and multiply reflected click signals received on the horizontal array. By accounting for transmission loss modeled using an ocean waveguide-acoustic propagation model, the sperm whale detection range was found to exceed 60 km in low to moderate sea state conditions after coherent array processing.

Image-Guided Surgery of Primary Breast Cancer Using Ultrasound Phased Arrays

DTIC Science & Technology

2004-07-01

applications using high-intensity focused ultrasound ( HIFU ). We tems, Once the real-time imaging capability is available for have shown that this dual-mode...Arrays Emad S. Ebbini, PI Introduction High-intensity focus ultrasound ( HIFU ) is gaining wider acceptance in noninvasive or minimally invasive targeting of...Methods in Ultrasound Imaging, ISBI 2004, Arlington, VA, April 2004. III. Yao and Ebbini, "Real-Time Monitoring of the Transients of HIFU -Induced Lesions

Focal Plane Array Shutter Mechanism of the JWST NIRSpec Detector System

NASA Technical Reports Server (NTRS)

Hale, Kathleen; Sharma, Rajeev

2006-01-01

This viewgraph presentation reviews the requirements, chamber location, shutter system design, stepper motor specifications, dry lubrication, control system, the environmental cryogenic function testing and the test results of the Focal Plane Array Shutter mechanism for the James Webb Space Telescope Near Infrared Spectrum Detector system. Included are design views of the location for the Shutter Mechanism, lubricant (lubricated with Molybdenum Di Sulfide) thickness, and information gained from the cryogenic testing.

Σ-Δ modulator for a programmable gain, low-power, high-linearity automotive sensor interface

NASA Astrophysics Data System (ADS)

de la Rosa, Jose M.; Medeiro, Fernando; Perez-Verdu, Belen; del Rio, Rocio; Rodriguez-Vazquez, Angel

2003-04-01

Smart sensors play a critical role in modern automotive electronic systems, covering a wide range of data capturing functions and operating under adverse environmental conditions - temperature range of [-40¦C,175¦C]. In such sensors, the signal provided by transducers is composed of an offset voltage, which depends on the manufacturing process, and a low-frequency signal carrying the information. In practice, the offset voltage is subject to temperature variations, thus causing a shifting of the signal range to be measured. Therefore, the measuring circuit driving the sensor, normally formed by a low-noise preamplifier and an Analog-to-Digital Converter (ADC), must accommodate the complete range of possible offsets and real signals. In this scenario, the use of ADCs based on Sigma-Delta Modulators (SDMs) is convenient for several reasons. On the one hand, the noise-shaping performed by SDMs allows to achieve high resolution (16-17bits), in the band of interest (10-20kHz), with less power consumption than full Nyquist ADCs. On the other hand, the action of feedback renders SDMs very linear, and high-linearity is a must for automotive applications. Last but not least, the robustness of SDMs with respect to circuit imperfections make them suitable to include programmable gain without significant performance degradation. This feature allows to accommodate the complete range of possible offsets and information signals in a sensor interface with relaxed specifications for the preamplifier circuitry. This paper describes the design and implementation of a third-order cascade (2-1) SDM with programmable gain in a 0.35mm CMOS technology - the type of technology commonly employed for automotive applications (deep submicron is mostly employed for telecom). It is capable of handling signals up to 20-kHz bandwidth with 17-bit resolution. The programmable gain is implemented by a capacitor array whose unitary capacitors are connected or disconnected depending on the value of

Magnetic arrays

DOEpatents

Trumper, D.L.; Kim, W.; Williams, M.E.

1997-05-20

Electromagnet arrays are disclosed which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness. 12 figs.

Gain of the short arm of chromosome 2 (2p) is a frequent recurring chromosome aberration in untreated chronic lymphocytic leukemia (CLL) at advanced stages.

PubMed

Chapiro, Elise; Leporrier, Nathalie; Radford-Weiss, Isabelle; Bastard, Christian; Mossafa, Hossein; Leroux, Dominique; Tigaud, Isabelle; De Braekeleer, Marc; Terré, Christine; Brizard, Françoise; Callet-Bauchu, Evelyne; Struski, Stéphanie; Veronese, Lauren; Fert-Ferrer, Sandra; Taviaux, Sylvie; Lesty, Claude; Davi, Frédéric; Merle-Béral, Hélène; Bernard, Olivier A; Sutton, Laurent; Raynaud, Sophie D; Nguyen-Khac, Florence

2010-01-01

Using array-based CGH, we identified 2p gain in 22/78 (28%) untreated Binet stages B/C CLL, which was the second most frequent copy number change after 13q deletion. It never occurred as a sole abnormality and was associated with other changes (6q deletion; 1p gain). The region of 2p gain frequently included two oncogenes, REL and MYCN. All patients with gain of REL were unmutated for IGHV (p=0.03). Gain of MYCN was associated with increased mRNA expression (p=0.005), suggesting a pathogenic role for MYCN. Gain of 2p appears to be a marker of progression and may contribute to the poor prognosis. 2009 Elsevier Ltd. All rights reserved.

Planetary and deep space requirements for photovoltaic solar arrays

NASA Technical Reports Server (NTRS)

Bankston, C. P.; Bennett, R. B.; Stella, P. M.

1995-01-01

In the past 25 years, the majority of interplanetary spacecraft have been powered by nuclear sources. However, as the emphasis on smaller, low cost missions gains momentum, the majority of missions now being planned will use photovoltaic solar arrays. This will present challenges to the solar array builders, inasmuch as planetary requirements usually differ from earth orbital requirements. In addition, these requirements often differ greatly, depending on the specific mission; for example, inner planets vs. outer planets, orbiters vs. flybys, spacecraft vs. landers, and so on. Also, the likelihood of electric propulsion missions will influence the requirements placed on solar array developers. The paper will discuss representative requirements for a range of planetary missions now in the planning stages. Insofar as inner planets are concerned, a Mercury orbiter is being studied with many special requirements. Solar arrays would be exposed to high temperatures and a potentially high radiation environment, and will need to be increasingly pointed off sun as the vehicle approaches Mercury. Identification and development of cell materials and arrays at high incidence angles will be critical to the design. Missions to the outer solar system that have been studied include a Galilean orbiter and a flight to the Kuiper belt. While onboard power requirements would be small (as low as 10 watts), the solar intensity will require relatively large array areas. As a result, such missions will demand extremely compact packaging and low mass structures to conform to launch vehicle constraints. In turn, the large are, low mass designs will impact allowable spacecraft loads. Inflatable array structures, with and without concentration, and multiband gap cells will be considered if available. In general, the highest efficiency cell technologies operable under low intensity, low temperature conditions are needed. Solar arrays will power missions requiring as little as approximately 100

Nanopillar arrays on semiconductor membranes as electron emission amplifiers.

PubMed

Qin, Hua; Kim, Hyun-Seok; Blick, Robert H

2008-03-05

A new transmission-type electron multiplier was fabricated from silicon-on-insulator (SOI) material by integrating an array of one-dimensional (1D) silicon nanopillars onto a two-dimensional (2D) silicon membrane. Primary electrons are injected into the nanopillar-membrane (NPM) system from the flat surface of the membrane, while electron emission from the nanopillars is probed by an anode. The secondary electron yield (SEY) from the nanopillars in the current device is found to be about 1.8 times that of the plain silicon membrane. This gain in electron number is slightly enhanced by the electric field applied from the anode. Further optimization of the dimensions of the NPM and an application of field emission promise an even higher gain for detector applications and allow for probing of electronic/mechanical excitations in an NPM system stimulated by incident particles or radiation.

System-Level Performance of Antenna Arrays in CDMA-Based Cellular Mobile Radio Systems

NASA Astrophysics Data System (ADS)

Czylwik, Andreas; Dekorsy, Armin

2004-12-01

Smart antennas exploit the inherent spatial diversity of the mobile radio channel, provide an antenna gain, and also enable spatial interference suppression leading to reduced intracell as well as intercell interference. Especially, for the downlink of future CDMA-based mobile communications systems, transmit beamforming is seen as a well-promising smart antenna technique. The main objective of this paper is to study the performance of diverse antenna array topologies when applied for transmit beamforming in the downlink of CDMA-based networks. In this paper, we focus on uniform linear array (ULA) and uniform circular array (UCA) topologies. For the ULA, we consider three-sector base stations with one linear array per sector. While recent research on downlink beamforming is often restricted to one single cell, this study takes into account the important impact of intercell interference on the performance by evaluating complete networks. Especially, from the operator perspective, system capacity and system coverage are very essential parameters of a cellular system so that there is a clear necessity of intensive system level investigations. Apart from delivering assessments on the performance of the diverse antenna array topologies, in the paper also different antenna array parameters, such as element spacing and beamwidth of the sector antennas, are optimized. Although we focus on the network level, fast channel fluctuations are taken into account by including them analytically into the signal-to-interference calculation.

Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

NASA Astrophysics Data System (ADS)

Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

1986-01-01

A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

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.

Nanocylinder arrays

DOEpatents

Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

2007-03-13

Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

Nanocylinder arrays

DOEpatents

Tuominen, Mark [Shutesbury, MA; Schotter, Joerg [Bielefeld, DE; Thurn-Albrecht, Thomas [Freiburg, DE; Russell, Thomas P [Amherst, MA

2009-08-11

Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

Research on calibration error of carrier phase against antenna arraying

NASA Astrophysics Data System (ADS)

Sun, Ke; Hou, Xiaomin

2016-11-01

It is the technical difficulty of uplink antenna arraying that signals from various quarters can not be automatically aligned at the target in deep space. The size of the far-field power combining gain is directly determined by the accuracy of carrier phase calibration. It is necessary to analyze the entire arraying system in order to improve the accuracy of the phase calibration. This paper analyzes the factors affecting the calibration error of carrier phase of uplink antenna arraying system including the error of phase measurement and equipment, the error of the uplink channel phase shift, the position error of ground antenna, calibration receiver and target spacecraft, the error of the atmospheric turbulence disturbance. Discuss the spatial and temporal autocorrelation model of atmospheric disturbances. Each antenna of the uplink antenna arraying is no common reference signal for continuous calibration. So it must be a system of the periodic calibration. Calibration is refered to communication of one or more spacecrafts in a certain period. Because the deep space targets are not automatically aligned to multiplexing received signal. Therefore the aligned signal should be done in advance on the ground. Data is shown that the error can be controlled within the range of demand by the use of existing technology to meet the accuracy of carrier phase calibration. The total error can be controlled within a reasonable range.

Ultra-Wideband Phased Array for Millimeter-Wave 5G and ISM

NASA Technical Reports Server (NTRS)

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

2016-01-01

Growing mobile data consumption has prompted the exploration of the millimeter-wave spectrum for large bandwidth, high speed communications. However, the allocated bands are spread across a wide swath of spectrum: fifth generation mobile architecture (5G): 28, 38, 39, 64-71 GHz, as well as Industrial, Scientific, and Medical bands (ISM): 24 and 60 GHz. Moreover, high gain phased arrays are required to overcome the significant path loss associated with these frequencies. Further, it is necessary to incorporate several of these applications in a single, small size and low cost platform. To this end, we have developed a scanning, Ultra-Wideband (UWB) array which covers all 5G, ISM, and other mm-W bands from 24-72 GHz. Critically, this is accomplished using mass-production Printed Circuit Board (PCB) fabrication.

Self-Positioned Nanosized Mask for Transparent and Flexible Ferroelectric Polymer Nanodiodes Array.

PubMed

Hyun, Seung; Kwon, Owoong; Choi, Chungryong; Vincent Joseph, Kanniyambatti L; Kim, Yunseok; Kim, Jin Kon

2016-10-12

High density arrays of ferroelectric polymer nanodiodes have gained strong attention for next-generation transparent and flexible nonvolatile resistive memory. Here, we introduce a facile and innovative method to fabricate ferroelectric polymer nanodiode array on an ITO-coated poly(ethylene terephthalate) (PET) substrate by using block copolymer self-assembly and oxygen plasma etching. First, polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP) micelles were spin-coated on poly(vinylidene fluoride-ran-trifluoroethylene) copolymer (P(VDF-TrFE)) film/ITO-coated PET substrate. After the sample was immersed in a gold precursor (HAuCl 4 ) containing solution, which strongly coordinates with nitrogen group in P2VP, oxygen plasma etching was performed. During the plasma etching, coordinated gold precursors became gold nanoparticles (GNPs), which successfully acted as self-positioned etching mask to fabricate a high density array of P(VDF-TrFE)) nanoislands with GNP at the top. Each nanoisland shows clearly individual diode property, as confirmed by current-voltage (I-V) curve. Furthermore, due to the transparent and flexible nature of P(VDF-TrFE)) nanoisland as well as the substrate, the P(VDF-TrFE) nanodiode array was highly tranparent, and the diode property was maintained even after a large number of bendings (for instance, 1000 times). The array could be used as the next-generation tranparent and flexible nonvolatile memory device.

Global impact of accelerated plant breeding: Evidence from a meta-analysis on rice breeding.

PubMed

Lenaerts, Bert; de Mey, Yann; Demont, Matty

2018-01-01

Rice breeders in Asia and elsewhere in the world have long overlooked trying to shorten the time it takes to develop new varieties. Plant breeders have proposed a technique called Rapid Generation Advance (RGA) as a way to accelerate the results of public rice breeding programs. However, little is known about RGA's potential impact. Here, we present the first results of a global impact study of RGA. More specifically, we calculated the multiplicator effects of RGA on the research benefits generated by conventional rice breeding programs and applied them to a meta-analysis of selected impact studies in the literature. These insights are a first crucial step in developing a targeted approach for disseminating RGA technology among rice breeders to accelerate the impact of their public rice breeding programs around the world. We show that the additional benefits due to time savings are considerable and offer some insights into the economics of breeding. Our results confirm that the adoption of accelerated breeding would lead to substantial advantages to rice breeding programs and the earlier variety release leads to significant economic benefits to society. This can be important to policy makers when reshaping their public breeding methods and optimising their return on research investments in breeding.

Three gangliogliomas: results of GTG-banding, SKY, genome-wide high resolution SNP-array, gene expression and review of the literature.

PubMed

Xu, Li-Xin; Holland, Heidrun; Kirsten, Holger; Ahnert, Peter; Krupp, Wolfgang; Bauer, Manfred; Schober, Ralf; Mueller, Wolf; Fritzsch, Dominik; Meixensberger, Jürgen; Koschny, Ronald

2015-04-01

According to the World Health Organization gangliogliomas are classified as well-differentiated and slowly growing neuroepithelial tumors, composed of neoplastic mature ganglion and glial cells. It is the most frequent tumor entity observed in patients with long-term epilepsy. Comprehensive cytogenetic and molecular cytogenetic data including high-resolution genomic profiling (single nucleotide polymorphism (SNP)-array) of gangliogliomas are scarce but necessary for a better oncological understanding of this tumor entity. For a detailed characterization at the single cell and cell population levels, we analyzed genomic alterations of three gangliogliomas using trypsin-Giemsa banding (GTG-banding) and by spectral karyotyping (SKY) in combination with SNP-array and gene expression array experiments. By GTG and SKY, we could confirm frequently detected chromosomal aberrations (losses within chromosomes 10, 13 and 22; gains within chromosomes 5, 7, 8 and 12), and identify so far unknown genetic aberrations like the unbalanced non-reciprocal translocation t(1;18)(q21;q21). Interestingly, we report on the second so far detected ganglioglioma with ring chromosome 1. Analyses of SNP-array data from two of the tumors and respective germline DNA (peripheral blood) identified few small gains and losses and a number of copy-neutral regions with loss of heterozygosity (LOH) in germline and in tumor tissue. In comparison to germline DNA, tumor tissues did not show substantial regions with significant loss or gain or with newly developed LOH. Gene expression analyses of tumor-specific genes revealed similarities in the profile of the analyzed samples regarding different relevant pathways. Taken together, we describe overlapping but also distinct and novel genetic aberrations of three gangliogliomas. © 2014 Japanese Society of Neuropathology.

Synthesis Study of a 6-Element Non-Uniform Array with Tilted Elements for CLARREO Project

NASA Technical Reports Server (NTRS)

Jamnejad, Vahraz; Hoorfar, Ahmad

2012-01-01

This paper presents the results of a preliminary study of the gain/pattern properties of a 6-element Radio Occultation (RO) array for the proposed CLARREO (Climate Absolute Radiance and Refractivity Observatory (CLARREO) Project. CLARREO is one of the 4 highest priority missions recommended in the National Research Council Earth Science Decadal Survey.

A 16 element quasi-optical FET oscillator power combining array with external injection locking

NASA Astrophysics Data System (ADS)

Birkeland, Joel; Itoh, Tatsuo

1992-03-01

The authors present analysis, design and experimental results of a 16 element planar oscillator array for quasi-optical power combining. Each element in the array consists of a single FET oscillator with an input port for injection of the locking signal, and an output port which is connected to a patch radiator. The array is synchronized using a 16-way power dividing network which distributes the locking signal to the oscillating elements. The array is constructed using a two-sided microstrip configuration, with the oscillators and feed network on one side of a ground plane, and the patch radiators on the opposite side. An effective radiated power (ERP) of 28.2 W CW with an isotropic conversion gain of 9.9 dB was measured at 6 GHz. For an injected power of 10.3 dBm, a locking range of 453 MHz at a center frequency of 6.015 GHz was obtained; a bandwidth of 7.5 percent. Because of the simple nature of the individual oscillator elements, this approach is well suited to MMIC implementation.

Surveying Low-Mass Star Formation with the Submillimeter Array

NASA Astrophysics Data System (ADS)

Dunham, Michael

2018-01-01

Large astronomical surveys yield important statistical information that can’t be derived from single-object and small-number surveys. In this talk I will review two recent surveys in low-mass star formation undertaken by the Submillimeter Array (SMA): a millimeter continuum survey of disks surrounding variably accreting young stars, and a complete continuum and molecular line survey of all protostars in the nearby Perseus Molecular Cloud. I will highlight several new insights into the processes by which low-mass stars gain their mass that have resulted from the statistical power of these surveys.

Effects of self-coupling and asymmetric output on metastable dynamical transient firing patterns in arrays of neurons with bidirectional inhibitory coupling.

PubMed

Horikawa, Yo

2016-04-01

Metastable dynamical transient patterns in arrays of bidirectionally coupled neurons with self-coupling and asymmetric output were studied. First, an array of asymmetric sigmoidal neurons with symmetric inhibitory bidirectional coupling and self-coupling was considered and the bifurcations of its steady solutions were shown. Metastable dynamical transient spatially nonuniform states existed in the presence of a pair of spatially symmetric stable solutions as well as unstable spatially nonuniform solutions in a restricted range of the output gain of a neuron. The duration of the transients increased exponentially with the number of neurons up to the maximum number at which the spatially nonuniform steady solutions were stabilized. The range of the output gain for which they existed reduced as asymmetry in a sigmoidal output function of a neuron increased, while the existence range expanded as the strength of inhibitory self-coupling increased. Next, arrays of spiking neuron models with slow synaptic inhibitory bidirectional coupling and self-coupling were considered with computer simulation. In an array of Class 1 Hindmarsh-Rose type models, in which each neuron showed a graded firing rate, metastable dynamical transient firing patterns were observed in the presence of inhibitory self-coupling. This agreed with the condition for the existence of metastable dynamical transients in an array of sigmoidal neurons. In an array of Class 2 Bonhoeffer-van der Pol models, in which each neuron had a clear threshold between firing and resting, long-lasting transient firing patterns with bursting and irregular motion were observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

A simple uniformity test for ultrasound phased arrays.

PubMed

Dudley, Nicholas J; Woolley, Darren J

2016-09-01

It is difficult to test phased array ultrasound transducers for non functioning elements. We aimed to modify a widely performed test to improve its ease and effectiveness for these arrays. A paperclip was slowly moved along the transducer array, with the scanner operating in M-mode, imaging at a fundamental frequency with automatic gain and grey scale adjustment disabled. Non-functioning elements are identified by a dark vertical line in the image. The test was repeated several times for each transducer, looking for consistency of results. 2 transducers, with faults already shown by electronic transducer testing, were used to validate the method. 23 transducers in clinical use were tested. The results of the modified test on the 2 faulty transducers agreed closely with electronic transducer testing results. The test indicated faults in 5 of the 23 transducers in clinical use: 3 with a single failed element and 2 with non-uniform sensitivity. 1 transducer with non-uniform sensitivity had undergone lens repair; the new lens was visibly non-uniform in thickness and further testing showed a reduction in depth of penetration and a loss of elevational focus in comparison with a new transducer. The modified test is capable of detecting non-functioning elements. Further work is required to provide a better understanding of more subtle faults. Copyright © 2016 Associazione Italiana di Fisica Medica. All rights reserved.

Two-dimensional beam steering array using planar eight-element composite right/left-handed leaky-wave antennas

NASA Astrophysics Data System (ADS)

Sanada, Atsushi

2008-08-01

A two-dimensional beam steering array composed of an eight-element antenna array using composite right/left-handed leaky-wave antennas fed by an 8 × 8 Butler matrix network is designed at X-band. An eight-way beam switching in one direction by input port switching and a continuous beam steering in the other direction by frequency sweep are achieved. A wide range beam steering operation covering from -55 to +53 degrees by port switching and from -37 to +27 degrees by frequency sweep is demonstrated with the maximum gain of 9.2 dBi.

SiPM detectors for the ASTRI project in the framework of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Billotta, Sergio; Marano, Davide; Bonanno, Giovanni; Belluso, Massimiliano; Grillo, Alessandro; Garozzo, Salvatore; Romeo, Giuseppe; Timpanaro, Maria Cristina; Maccarone, Maria Concetta C.; Catalano, Osvaldo; La Rosa, Giovanni; Sottile, Giuseppe; Impiombato, Domenico; Gargano, Carmelo; Giarrusso, Salavtore

2014-07-01

The Cherenkov Telescope Array (CTA) is a worldwide new generation project aimed at realizing an array of a hundred ground based gamma-ray telescopes. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is the Italian project whose primary target is the development of an end-to-end prototype, named ASTRI SST-2M, of the CTA small size class of telescopes devoted to investigation of the highest energy region, from 1 to 100 TeV. Next target is the implementation of an ASTRI/CTA mini-array based on seven identical telescopes. Silicon Photo-Multipliers (SiPMs) are the semiconductor photosensor devices designated to constitute the camera detection system at the focal plane of the ASTRI telescopes. SiPM photosensors are suitable for the detection of the Cherenkov flashes, since they are very fast and sensitive to the light in the 300-700nm wavelength spectrum. Their drawbacks compared to the traditional photomultiplier tubes are high dark count rates, after-pulsing and optical cross-talk contributions, and intrinsic gains strongly dependent on temperature. Nonetheless, for a single pixel, the dark count rate is well below the Night Sky Background, the effects of cross-talk and afterpulses are typically lower than 20%, and the gain can be kept stable against temperature variations by means of adequate bias voltage compensation strategies. This work presents and discusses some experimental results from a large set of measurements performed on the SiPM sensors to be used for the ASTRI SST-2M prototype camera and on recently developed detectors demonstrating outstanding performance for the future evolution of the project in the ASTRI/CTA mini-array.

Joint stars phased array radar antenna

NASA Astrophysics Data System (ADS)

Shnitkin, Harold

1994-10-01

The Joint STARS phased array radar system is capable of performing long range airborne surveillance and was used during the Persian Gulf war on two E8-A aircraft to fly many around-the-clock missions to monitor the Kuwait and Iraq battlefield from a safe distance behind the front lines. This paper is a follow-on to previous publications on the subject of the Joint STARS antenna and deals mainly with mission performance and technical aspects not previously covered. Radar data of troop movements and armament installations will be presented, a brief review of the antenna design is given, followed by technical discussions concerning the three-port interferometry, gain and sidelobe design approach, cost control, range test implementation and future improvements.

Electronic Switch Arrays for Managing Microbattery Arrays

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad; Alahmad, Mahmoud; Sukumar, Vinesh; Zghoul, Fadi; Buck, Kevin; Hess, Herbert; Li, Harry; Cox, David

2008-01-01

Integrated circuits have been invented for managing the charging and discharging of such advanced miniature energy-storage devices as planar arrays of microscopic energy-storage elements [typically, microscopic electrochemical cells (microbatteries) or microcapacitors]. The architecture of these circuits enables implementation of the following energy-management options: dynamic configuration of the elements of an array into a series or parallel combination of banks (subarrarys), each array comprising a series of parallel combination of elements; direct addressing of individual banks for charging/or discharging; and, disconnection of defective elements and corresponding reconfiguration of the rest of the array to utilize the remaining functional elements to obtain the desited voltage and current performance. An integrated circuit according to the invention consists partly of a planar array of field-effect transistors that function as switches for routing electric power among the energy-storage elements, the power source, and the load. To connect the energy-storage elements to the power source for charging, a specific subset of switches is closed; to connect the energy-storage elements to the load for discharging, a different specific set of switches is closed. Also included in the integrated circuit is circuitry for monitoring and controlling charging and discharging. The control and monitoring circuitry, the switching transistors, and interconnecting metal lines are laid out on the integrated-circuit chip in a pattern that registers with the array of energy-storage elements. There is a design option to either (1) fabricate the energy-storage elements in the corresponding locations on, and as an integral part of, this integrated circuit; or (2) following a flip-chip approach, fabricate the array of energy-storage elements on a separate integrated-circuit chip and then align and bond the two chips together.

Observations of Interplanetary Scintillation (IPS) Using the Mexican Array Radio Telescope (MEXART)

NASA Astrophysics Data System (ADS)

Mejia-Ambriz, J. C.; Villanueva-Hernandez, P.; Gonzalez-Esparza, J. A.; Aguilar-Rodriguez, E.; Jeyakumar, S.

2010-08-01

The Mexican Array Radio Telescope (MEXART) consists of a 64×64 (4096) full-wavelength dipole antenna array, operating at 140 MHz, with a bandwidth of 2 MHz, occupying about 9660 square meters (69 m × 140 m) ( http://www.mexart.unam.mx ). This is a dedicated radio array for Interplanetary Scintillation (IPS) observations located at latitude 19°48'N, longitude 101°41'W. We characterize the performance of the system. We report the first IPS observations with the instrument, employing a Butler Matrix (BM) of 16×16 ports, fed by 16 east - west lines of 64 dipoles (1/4 of the total array). The BM displays a radiation pattern of 16 beams at different declinations (from -48, to +88 degrees). We present a list of 19 strong IPS radio sources (having at least 3 σ in power gain) detected by the instrument. We report the power spectral analysis procedure of the intensity fluctuations. The operation of MEXART will allow us a better coverage of solar wind disturbances, complementing the data provided by the other, previously built, instruments.

A Cryogenic SiGe Low-noise Amplifier Optimized for Phased-array Feeds

NASA Astrophysics Data System (ADS)

Groves, Wavley M., III; Morgan, Matthew A.

2017-08-01

The growing number of phased-array feeds (PAF) being built for radio astronomy demonstrates an increasing need for low-noise amplifiers (LNA), which are designed for repeatability, low noise, and ease of manufacture. Specific design features that help to achieve these goals include the use of unpackaged transistors (for cryogenic operation); single-polarity biasing; straight plug-in radio frequency (RF) interfaces to facilitate installation and re-work; and the use of off-the-shelf components. The focal L-band array for the Green Bank Telescope (FLAG) is a cooperative effort by Brigham Young University and the National Radio Astronomy Observatory using warm dipole antennae and cryogenic Silicon Germanium Heterojunction Bipolar Transistor (SiGe HBT) LNAs. These LNAs have an in band gain average of 38 dB and 4.85 Kelvin average noise temperature. Although the FLAG instrument was the driving instrument behind this development, most of the key features of the design and the advantages they offer apply broadly to other array feeds, including independent-beam and phased, and for many antenna types such as horn, dipole, Vivaldi, connected-bowtie, etc. This paper focuses on the unique requirements array feeds have for low-noise amplifiers and how amplifier manufacturing can accommodate these needs.

Superior broadband antireflection from buried Mie resonator arrays for high-efficiency photovoltaics

PubMed Central

Zhong, Sihua; Zeng, Yang; Huang, Zengguang; Shen, Wenzhong

2015-01-01

Establishing reliable and efficient antireflection structures is of crucial importance for realizing high-performance optoelectronic devices such as solar cells. In this study, we provide a design guideline for buried Mie resonator arrays, which is composed of silicon nanostructures atop a silicon substrate and buried by a dielectric film, to attain a superior antireflection effect over a broadband spectral range by gaining entirely new discoveries of their antireflection behaviors. We find that the buried Mie resonator arrays mainly play a role as a transparent antireflection structure and their antireflection effect is insensitive to the nanostructure height when higher than 150 nm, which are of prominent significance for photovoltaic applications in the reduction of photoexcited carrier recombination. We further optimally combine the buried Mie resonator arrays with micron-scale textures to maximize the utilization of photons, and thus have successfully achieved an independently certified efficiency of 18.47% for the nanostructured silicon solar cells on a large-size wafer (156 mm × 156 mm). PMID:25746848

CNV detection method optimized for high-resolution arrayCGH by normality test.

PubMed

Ahn, Jaegyoon; Yoon, Youngmi; Park, Chihyun; Park, Sanghyun

2012-04-01

High-resolution arrayCGH platform makes it possible to detect small gains and losses which previously could not be measured. However, current CNV detection tools fitted to early low-resolution data are not applicable to larger high-resolution data. When CNV detection tools are applied to high-resolution data, they suffer from high false-positives, which increases validation cost. Existing CNV detection tools also require optimal parameter values. In most cases, obtaining these values is a difficult task. This study developed a CNV detection algorithm that is optimized for high-resolution arrayCGH data. This tool operates up to 1500 times faster than existing tools on a high-resolution arrayCGH of whole human chromosomes which has 42 million probes whose average length is 50 bases, while preserving false positive/negative rates. The algorithm also uses a normality test, thereby removing the need for optimal parameters. To our knowledge, this is the first formulation for CNV detecting problems that results in a near-linear empirical overall complexity for real high-resolution data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Planetary and Deep Space Requirements for Photovoltaic Solar Arrays

NASA Technical Reports Server (NTRS)

Bankston, C. P.; Bennett, R. B.; Stella, P. M.

1995-01-01

In the past 25 years, the majority of interplanetary spacecraft have been powered by nuclear sources. However, as the emphasis on smaller, low cost missions gains momentum, more deep space missions now being planned have baselined photovoltaic solar arrays due to the low power requirements (usually significantly less than 100 W) needed for engineering and science payloads. This will present challenges to the solar array builders, inasmuch as planetary requirements usually differ from earth orbital requirements. In addition, these requirements often differ greatly, depending on the specific mission; for example, inner planets vs. outer planets, orbiters vs. flybys, spacecraft vs. landers, and so on. Also, the likelihood of electric propulsion missions will influence the requirements placed on solar array developers. This paper will discuss representative requirements for a range of planetary and deep space science missions now in the planning stages. We have divided the requirements into three categories: Inner planets and the sun; outer planets (greater than 3 AU); and Mars, cometary, and asteroid landers and probes. Requirements for Mercury and Ganymede landers will be covered in the Inner and Outer Planets sections with their respective orbiters. We will also discuss special requirements associated with solar electric propulsion (SEP). New technology developments will be needed to meet the demanding environments presented by these future applications as many of the technologies envisioned have not yet been demonstrated. In addition, new technologies that will be needed reside not only in the photovoltaic solar array, but also in other spacecraft systems that are key to operating the spacecraft reliably with the photovoltaics.

Array signal recovery algorithm for a single-RF-channel DBF array

NASA Astrophysics Data System (ADS)

Zhang, Duo; Wu, Wen; Fang, Da Gang

2016-12-01

An array signal recovery algorithm based on sparse signal reconstruction theory is proposed for a single-RF-channel digital beamforming (DBF) array. A single-RF-channel antenna array is a low-cost antenna array in which signals are obtained from all antenna elements by only one microwave digital receiver. The spatially parallel array signals are converted into time-sequence signals, which are then sampled by the system. The proposed algorithm uses these time-sequence samples to recover the original parallel array signals by exploiting the second-order sparse structure of the array signals. Additionally, an optimization method based on the artificial bee colony (ABC) algorithm is proposed to improve the reconstruction performance. Using the proposed algorithm, the motion compensation problem for the single-RF-channel DBF array can be solved effectively, and the angle and Doppler information for the target can be simultaneously estimated. The effectiveness of the proposed algorithms is demonstrated by the results of numerical simulations.

Ultra-Wideband Array in PCB for Millimeter-Wave 5G and ISM

NASA Technical Reports Server (NTRS)

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

2017-01-01

Growing mobile data consumption has prompted the exploration of the millimeter-wave spectrum for large bandwidth, high speed communications. However, the allocated bands are spread across a wide swath of spectrum: Fifth generation mobile architecture (5G): 28, 38, 39, 6471 GHz; Industrial, Scientific, and Medical bands (ISM): 24, 60 GHz. Moreover, high gain phased arrays are required to overcome the significant path loss associated with these frequencies. Further, it is necessary to incorporate several of these applications in a single, small size and low cost platform. To this end, we have developed a scanning, Ultra-Wideband (UWB) array which covers all 5G, ISM, and other mm-W bands from 2472 GHz. Critically, this is accomplished using mass-production Printed Circuit Board (PCB) fabrication. The results of this work are presented in this poster.

A 20-Channel Receive-Only Mouse Array Coil for a 3T Clinical MRI System

PubMed Central

Keil, Boris; Wiggins, Graham C.; Triantafyllou, Christina; Wald, Lawrence L.; Meise, Florian M.; Schreiber, Laura M.; Klose, Klaus J.; Heverhagen, Johannes T.

2010-01-01

A 20-channel phased-array coil for Magnetic Resonance Imaging (MRI) of mice has been designed, constructed and validated with bench measurements and high resolution accelerated imaging. The technical challenges of designing a small, high density array have been overcome using individual small-diameter coil elements arranged on a cylinder in a hexagonal overlapping design with adjacent low impedance preamplifiers to further decouple the array elements. Signal-to-noise ratio (SNR) and noise amplification in accelerated imaging were simulated and quantitatively evaluated in phantoms and in vivo mouse images. Comparison between the 20-channel mouse array and a length-matched quadrature driven small animal birdcage coil showed an SNR increase at the periphery and in the center of the phantom of 3-fold and 1.3-fold, respectively. Comparison to a shorter but SNR-optimized birdcage coil (aspect ratio 1:1 and only half mouse coverage) showed an SNR gain of 2-fold at the edge of the phantom and similar SNR in the center. G-factor measurements indicate that the coil is well suited to acquire highly accelerated images. PMID:21433066

Arc dynamics of a pulsed DC nitrogen rotating gliding arc discharge

NASA Astrophysics Data System (ADS)

Zhu, Fengsen; Zhang, Hao; Li, Xiaodong; Wu, Angjian; Yan, Jianhua; Ni, Mingjiang; Tu, Xin

2018-03-01

In this study, a novel pulsed direct current (DC) rotating gliding arc (RGA) plasma reactor co-driven by an external magnetic field and a tangential gas flow has been developed. The dynamic characteristics of the rotating gliding arc have been investigated by means of numerical simulation and experiment. The simulation results show that a highly turbulent vortex flow can be generated at the bottom of the RGA reactor to accelerate the arc rotation after arc ignition, whereas the magnitude of gas velocity declined significantly along the axial direction of the RGA reactor. The calculated arc rotation frequency (14.4 Hz) is reasonably close to the experimental result (18.5 Hz) at a gas flow rate of 10 l min-1. In the presence of an external magnet, the arc rotation frequency is around five times higher than that of the RGA reactor without using a magnet, which suggests that the external magnetic field plays a dominant role in the maintenance of the arc rotation in the upper zone of the RGA reactor. In addition, when the magnet is placed outside the reactor reversely to form a reverse external magnetic field, the arc can be stabilized at a fixed position in the inner wall of the outer electrode at a critical gas flow rate of 16 l min-1.

High-channel-count, high-density microelectrode array for closed-loop investigation of neuronal networks.

PubMed

Tsai, David; John, Esha; Chari, Tarun; Yuste, Rafael; Shepard, Kenneth

2015-01-01

We present a system for large-scale electrophysiological recording and stimulation of neural tissue with a planar topology. The recording system has 65,536 electrodes arranged in a 256 × 256 grid, with 25.5 μm pitch, and covering an area approximately 42.6 mm(2). The recording chain has 8.66 μV rms input-referred noise over a 100 ~ 10k Hz bandwidth while providing up to 66 dB of voltage gain. When recording from all electrodes in the array, it is capable of 10-kHz sampling per electrode. All electrodes can also perform patterned electrical microstimulation. The system produces ~ 1 GB/s of data when recording from the full array. To handle, store, and perform nearly real-time analyses of this large data stream, we developed a framework based around Xilinx FPGAs, Intel x86 CPUs and the NVIDIA Streaming Multiprocessors to interface with the electrode array.

Phase sensitive distributed vibration sensing based on ultraweak fiber Bragg grating array using double-pulse

NASA Astrophysics Data System (ADS)

Liu, Tao; Wang, Feng; Zhang, Xuping; Zhang, Lin; Yuan, Quan; Liu, Yu; Yan, Zhijun

2017-08-01

A distributed vibration sensing technique using double-optical-pulse based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR) and an ultraweak fiber Bragg grating (UWFBG) array is proposed for the first time. The single-mode sensing fiber is integrated with the UWFBG array that has uniform spatial interval and ultraweak reflectivity. The relatively high reflectivity of the UWFBG, compared with the Rayleigh scattering, gains a high signal-to-noise ratio for the signal, which can make the system achieve the maximum detectable frequency limited by the round-trip time of the probe pulse in fiber. A corresponding experimental ϕ-OTDR system with a 4.5 km sensing fiber integrated with the UWFBG array was setup for the evaluation of the system performance. Distributed vibration sensing is successfully realized with spatial resolution of 50 m. The sensing range of the vibration frequency can cover from 3 Hz to 9 kHz.

Memristor-based programmable logic array (PLA) and analysis as Memristive networks.

PubMed

Lee, Kwan-Hee; Lee, Sang-Jin; Kim, Seok-Man; Cho, Kyoungrok

2013-05-01

A Memristor theorized by Chua in 1971 has the potential to dramatically influence the way electronic circuits are designed. It is a two terminal device whose resistance state is based on the history of charge flow brought about as the result of the voltage being applied across its terminals and hence can be thought of as a special case of a reconfigurable resistor. Nanoscale devices using dense and regular fabrics such as Memristor cross-bar is promising new architecture for System-on-Chip (SoC) implementations in terms of not only the integration density that the technology can offer but also both improved performance and reduced power dissipation. Memristor has the capacity to switch between high and low resistance states in a cross-bar circuit configuration. The cross-bars are formed from an array of vertical conductive nano-wires cross a second array of horizontal conductive wires. Memristors are realized at the intersection of the two wires in the array through appropriate processing technology such that any particular wire in the vertical array can be connected to a wire in the horizontal array by switching the resistance of a particular intersection to a low state while other cross-points remain in a high resistance state. However the approach introduces a number of challenges. The lack of voltage gain prevents logic being cascaded and voltage level degradation affects robustness of the operation. Moreover the cross-bars introduce sneak current paths when two or more cross points are connected through the switched Memristor. In this paper, we propose Memristor-based programmable logic array (PLA) architecture and develop an analytical model to analyze the logic level on the memristive networks. The proposed PLA architecture has 12 inputs maximum and can be cascaded for more input variables with R(off)/R(on) ratio in the range from 55 to 160 of Memristors.

Superconducting Quantum Arrays for Wideband Antennas and Low Noise Amplifiers

NASA Technical Reports Server (NTRS)

Mukhanov, O.; Prokopemko, G.; Romanofsky, Robert R.

2014-01-01

Superconducting Quantum Iinetference Filters (SQIF) consist of a two-dimensional array of niobium Josephson Junctions formed into N loops of incommensurate area. This structure forms a magnetic field (B) to voltage transducer with an impulse like response at B0. In principle, the signal-to-noise ratio scales as the square root of N and the noise can be made arbitrarily small (i.e. The SQIF chips are expected to exhibit quantum limited noise performance). A gain of about 20 dB was recently demonstrated at 10 GHz.

Extragalactic radio surveys in the pre-Square Kilometre Array era

PubMed Central

2017-01-01

The era of the Square Kilometre Array is almost upon us, and pathfinder telescopes are already in operation. This brief review summarizes our current knowledge of extragalactic radio sources, accumulated through six decades of continuum surveys at the low-frequency end of the electromagnetic spectrum and the extensive complementary observations at other wavelengths necessary to gain this understanding. The relationships between radio survey data and surveys at other wavelengths are discussed. Some of the outstanding questions are identified and prospects over the next few years are outlined. PMID:28791175

Channel length scaling behavior in transistors based on individual versus dense arrays of carbon nanotubes

NASA Astrophysics Data System (ADS)

Brady, Gerald J.; Jinkins, Katherine R.; Arnold, Michael S.

2017-09-01

Recent advances in the solution-phase sorting and assembly of semiconducting single-walled carbon nanotubes (SWCNTs) have enabled significant gains in the performance of field-effect transistors (FETs) constructed from dense arrays of aligned SWCNTs. However, the channel length (LCH) downscaling behaviors of these arrays, which contain some organizational disorder (i.e., rotational misalignment and non-uniform pitch), have not yet been studied in detail below LCH of 100 nm. This study compares the behaviors of individualized SWCNTs with arrays of aligned, solution-cast SWCNTs in FETs with LCH ranging from 30 to 240 nm. The on-state conductance of both individual and array SWCNTs rises with decreasing LCH. Nearly ballistic transport is observed for LCH < 40 nm in both cases, reaching a conductance of 0.82 Go per SWCNT in arrays, where Go = 2e2/h is the quantum conductance. In the off-state, the off-current and subthreshold swing of the individual SWCNTs remain nearly invariant with decreasing LCH whereas array SWCNT FETs suffer from increasing off-state current and deteriorating subthreshold swing for LCH below 100 nm. We analyze array disorder using atomic force microscopy, which shows that crossing SWCNTs that arise from misoriented alignment raise SWCNTs off of the substrate for large portions of the channel when LCH is small. Electrostatics modeling analysis indicates that these raised SWCNTs are a likely contributor to the deteriorating off-current and subthreshold characteristics of arrays. These results demonstrate that improved inter-SWCNT pitch uniformity and alignment with minimal inter-SWCNT interactions will be necessary in order for solution processed SWCNT arrays to reach subthreshold performance on par with isolated SWCNTs. These results are also promising because they show that arrays of solution-processed SWCNTs can nearly reach ballistic conductance in the on-state despite imperfections in pitch and alignment.

UHF Microstrip Antenna Array for Synthetic- Aperture Radar

NASA Technical Reports Server (NTRS)

Thomas, Robert F.; Huang, John

2003-01-01

An ultra-high-frequency microstrippatch antenna has been built for use in airborne synthetic-aperture radar (SAR). The antenna design satisfies requirements specific to the GeoSAR program, which is dedicated to the development of a terrain-mapping SAR system that can provide information on geology, seismicity, vegetation, and other terrain-related topics. One of the requirements is for ultra-wide-band performance: the antenna must be capable of operating with dual linear polarization in the frequency range of 350 plus or minus 80 MHz, with a peak gain of 10 dB at the middle frequency of 350 MHz and a gain of at least 8 dB at the upper and lower ends (270 and 430 MHz) of the band. Another requirement is compactness: the antenna must fit in the wingtip pod of a Gulfstream II airplane. The antenna includes a linear array of microstrip-patch radiating elements supported over square cavities. Each patch is square (except for small corner cuts) and has a small square hole at its center.

Concurrent array-based queue

DOEpatents

Heidelberger, Philip; Steinmacher-Burow, Burkhard

2015-01-06

According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.

DNA Copy Number Changes in Human Malignant Fibrous Histiocytomas by Array Comparative Genomic Hybridisation

PubMed Central

Kresse, Stine H.; Ohnstad, Hege O.; Bjerkehagen, Bodil; Myklebost, Ola; Meza-Zepeda, Leonardo A.

2010-01-01

Background Malignant fibrous histiocytomas (MFHs), or undifferentiated pleomorphic sarcomas, are in general high-grade tumours with extensive chromosomal aberrations. In order to identify recurrent chromosomal regions of gain and loss, as well as novel gene targets of potential importance for MFH development and/or progression, we have analysed DNA copy number changes in 33 MFHs using microarray-based comparative genomic hybridisation (array CGH). Principal findings In general, the tumours showed numerous gains and losses of large chromosomal regions. The most frequent minimal recurrent regions of gain were 1p33-p32.3, 1p31.3-p31.2 and 1p21.3 (all gained in 58% of the samples), as well as 1q21.2-q21.3 and 20q13.2 (both 55%). The most frequent minimal recurrent regions of loss were 10q25.3-q26.11, 13q13.3-q14.2 and 13q14.3-q21.1 (all lost in 64% of the samples), as well as 2q36.3-q37.2 (61%), 1q41 (55%) and 16q12.1-q12.2 (52%). Statistical analyses revealed that gain of 1p33-p32.3 and 1p21.3 was significantly associated with better patient survival (P = 0.021 and 0.046, respectively). Comparison with similar array CGH data from 44 leiomyosarcomas identified seven chromosomal regions; 1p36.32-p35.2, 1p21.3-p21.1, 1q32.1-q42.13, 2q14.1-q22.2, 4q33-q34.3, 6p25.1-p21.32 and 7p22.3-p13, which were significantly different in copy number between the MFHs and leiomyosarcomas. Conclusions A number of recurrent regions of gain and loss have been identified, some of which were associated with better patient survival. Several specific chromosomal regions with significant differences in copy number between MFHs and leiomyosarcomas were identified, and these aberrations may be used as additional tools for the differential diagnosis of MFHs and leiomyosarcomas. PMID:21085701

DYZ1 arrays show sequence variation between the monozygotic males

PubMed Central

2014-01-01

Background Monozygotic twins (MZT) are an important resource for genetical studies in the context of normal and diseased genomes. In the present study we used DYZ1, a satellite fraction present in the form of tandem arrays on the long arm of the human Y chromosome, as a tool to uncover sequence variations between the monozygotic males. Results We detected copy number variation, frequent insertions and deletions within the sequences of DYZ1 arrays amongst all the three sets of twins used in the present study. MZT1b showed loss of 35 bp compared to that in 1a, whereas 2a showed loss of 31 bp compared to that in 2b. Similarly, 3b showed 10 bp insertion compared to that in 3a. MZT1a germline DNA showed loss of 5 bp and 1b blood DNA showed loss of 26 bp compared to that of 1a blood and 1b germline DNA, respectively. Of the 69 restriction sites detected in DYZ1 arrays, MboII, BsrI, TspEI and TaqI enzymes showed frequent loss and or gain amongst all the 3 pairs studied. MZT1 pair showed loss/gain of VspI, BsrDI, AgsI, PleI, TspDTI, TspEI, TfiI and TaqI restriction sites in both blood and germline DNA. All the three sets of MZT showed differences in the number of DYZ1 copies. FISH signals reflected somatic mosaicism of the DYZ1 copies across the cells. Conclusions DYZ1 showed both sequence and copy number variation between the MZT males. Sequence variation was also noticed between germline and blood DNA samples of the same individual as we observed at least in one set of sample. The result suggests that DYZ1 faithfully records all the genetical changes occurring after the twining which may be ascribed to the environmental factors. PMID:24495361

Array-based comparative genomic hybridization in 190 Korean patients with developmental delay and/or intellectual disability: a single tertiary care university center study.

PubMed

Lee, Cha Gon; Park, Sang-Jin; Yun, Jun-No; Ko, Jung Min; Kim, Hyon-Ju; Yim, Shin-Young; Sohn, Young Bae

2013-11-01

This study analyzed and evaluated the demographic, clinical, and cytogenetic data [G-banded karyotyping and array-based comparative genomic hybridization (array CGH)] of patients with unexplained developmental delay or intellectual disability at a single Korean institution. We collected clinical and cytogenetic data based on retrospective charts at Ajou University Medical Center, Suwon, Korea from April 2008 to March 2012. A total of 190 patients were identified. Mean age was 5.1±1.87 years. Array CGH yielded abnormal results in 26 of 190 patients (13.7%). Copy number losses were about two-fold more frequent than gains. A total of 61.5% of all patients had copy number losses. The most common deletion disorders included 22q11.2 deletion syndrome, 15q11.2q12 deletion and 18q deletion syndrome. Copy number gains were identified in 34.6% of patients, and common diseases among these included Potocki-Lupski syndrome, 15q11-13 duplication syndrome and duplication 22q. Abnormal karyotype with normal array CGH results was exhibited in 2.6% of patients; theses included balanced translocation (n=2), inversion (n=2) and low-level mosaicism (n=1). Facial abnormalities (p<0.001) and failure to thrive were (p<0.001) also more frequent in the group of patients with abnormal CGH findings. Array CGH is a useful diagnostic tool in clinical settings in patients with developmental delay or intellectual disability combined with facial abnormalities or failure to thrive.

Increasing diversity in the geosciences through the AfricaArray geophysics field course

NASA Astrophysics Data System (ADS)

Vallejo, G.; Emry, E.; Galindo, B. L.; Carranza, V.; Gomez, C. D.; Ortiz, K.; Castro, J. G.; Guandique, J.; Falzone, C.; Webb, S. J.; Manzi, M.; Mngadi, S. B.; Stephens, K.; Chinamora, B.; Whitehead, R.; de Villiers, D. P.; Tshitlho, K.; Delhaye, R. P.; Smith, J. A.; Nyblade, A.

2014-12-01

For the past nine years, the AfricaArray diversity program, sponsored by industry, the National Science Foundation, and several partnering universities have supported outstanding U.S. STEM underrepresented minority undergraduates to gain field experience in near-surface geophysical techniques during an 8-week summer program at Penn State University and the University of Witwatersrand (Wits). The AfricaArray geophysics field school, which is run by Wits, has been teaching field-based geophysics to African students for over a decade. In the first 2-3 weeks of the program, the U.S. students are given basic instruction in near-surface geophysics, South African geology, and South African history and culture. The students then join the Wits AfricaArray geophysics field school - working alongside Wits students and students from several other African universities to map the shallow subsurface in prospective areas of South Africa for platinum mining. In addition to the primary goals of collecting and interpreting gravity, magnetic, resistivity, seismic refraction, seismic reflection, and EM data, students spend time mapping geologic units and gathering information on the physical properties of the rocks in the region (i.e. seismic velocity, density, and magnetic susceptibility). Subsurface targets include mafic dikes, faults, the water table, and overburden thickness. Upon returning to the U.S., students spend 2-3 weeks finalizing their project reports and presentations. The program has been effective at not only providing students with fundamental skills in applied geophysics, but also in fostering multicultural relationships, preparing students for graduate work in the geosciences, and attracting STEM students into the geosciences. Student presenters will discuss their experiences gained through the field school and give their impressions about how the program works towards the goal of increasing diversity in the geosciences in the U.S.

Arrays of Miniature Microphones for Aeroacoustic Testing

NASA Technical Reports Server (NTRS)

Shams, Qamar A.; Humphreys, William M.; Sealey, Bradley S.; Bartram, Scott M.; Zuckewar, Allan J.; Comeaux, Toby; Adams, James K.

2007-01-01

the entire array due to the flush mounting of all microphones (see right side of figure). The face sheet is made from a continuous glass-woven-fabric base impregnated with an epoxy resin binder. This material offers a combination of high mechanical strength and low dielectric loss, making it suitable for withstanding the harsh test section environment present in many wind tunnels, while at the same time protecting the underlying polyimide board. Customized signal-conditioning hardware consisting of line drivers and antialiasing filters are coupled with the array. The line drivers are constructed using low-supply-current, high-gain-bandwidth operational amplifiers designed to transmit the microphone signals several dozen feet from the array to external acquisition hardware. The anti-alias filters consist of individual Chebyshev low-pass filters (one for each microphone channel) housed on small printed-circuit boards mounted on one or more motherboards. The mother/daughter board design results in a modular system, which is easy to debug and service and which enables the filter characteristics to be changed by swapping daughter boards with ones containing different filter parameters. The filter outputs are passed to commercially- available acquisition hardware to digitize and store the conditioned microphone signals. Wind-tunnel testing of the new MEMS microphone polyimide mounting system shows that the array performance is comparable to that of traditional arrays, but with significantly less cost of construction.

A Novel Approach to Beam Steering Using Arrays Composed of Multiple Unique Radiating Modes

NASA Astrophysics Data System (ADS)

Labadie, Nathan Richard

Phased array antennas have found wide application in both radar and wireless communications systems particularly as implementation costs continue to decrease. The primary advantages of electronically scanned arrays are speed of beam scan and versatility of beamforming compared to mechanically scanned fixed beam antennas. These benefits come at the cost of a few well known design issues including element pattern rolloff and mutual coupling between elements. Our primary contribution to the field of research is the demonstration of significant improvement in phased array scan performance using multiple unique radiating modes. In short, orthogonal radiating modes have minimal coupling by definition and can also be generated with reduced rolloff at wide scan angles. In this dissertation, we present a combination of analysis, full-wave electromagnetic simulation and measured data to support our claims. The novel folded ring resonator (FRR) antenna is introduced as a wideband and multi-band element embedded in a grounded dielectric substrate. Multiple radiating modes of a small ground plane excited by a four element FRR array were also investigated. A novel hemispherical null steering antenna composed of two collocated radiating elements, each supporting a unique radiating mode, is presented in the context of an anti-jam GPS receiver application. Both the antenna aperture and active feed network were fabricated and measured showing excellent agreement with analytical and simulated data. The concept of using an antenna supporting multiple radiating modes for beam steering is also explored. A 16 element hybrid linear phased array was fabricated and measured demonstrating significantly improved scan range and scanned gain compared to a conventional phased array. This idea is expanded to 2 dimensional scanning arrays by analysis and simulation of a hybrid phased array composed of novel multiple mode monopole on patch antenna sub-arrays. Finally, we fabricated and

Similar Tensor Arrays - A Framework for Storage of Tensor Array Data

NASA Astrophysics Data System (ADS)

Brun, Anders; Martin-Fernandez, Marcos; Acar, Burak; Munoz-Moreno, Emma; Cammoun, Leila; Sigfridsson, Andreas; Sosa-Cabrera, Dario; Svensson, Björn; Herberthson, Magnus; Knutsson, Hans

This chapter describes a framework for storage of tensor array data, useful to describe regularly sampled tensor fields. The main component of the framework, called Similar Tensor Array Core (STAC), is the result of a collaboration between research groups within the SIMILAR network of excellence. It aims to capture the essence of regularly sampled tensor fields using a minimal set of attributes and can therefore be used as a “greatest common divisor” and interface between tensor array processing algorithms. This is potentially useful in applied fields like medical image analysis, in particular in Diffusion Tensor MRI, where misinterpretation of tensor array data is a common source of errors. By promoting a strictly geometric perspective on tensor arrays, with a close resemblance to the terminology used in differential geometry, (STAC) removes ambiguities and guides the user to define all necessary information. In contrast to existing tensor array file formats, it is minimalistic and based on an intrinsic and geometric interpretation of the array itself, without references to other coordinate systems.

Experimental Tests of UltraFlex Array Designs in Low Earth Orbital and Geosynchronous Charging Environments

NASA Technical Reports Server (NTRS)

Galofaro, Joel T.; Vayner, Boris V.; Hillard, Grover B.

2011-01-01

The present ground based investigations give the first definitive look describing the expected on-orbit charging behavior of Orion UltraFlex array coupons in the Low Earth Orbital and Geosynchronous Environments. Furthermore, it is important to note that the LEO charging environment also applies to the International Space Station as well as to the lunar mission charging environments. The GEO charging environment includes the bounding case for all lunar orbital and lunar surface mission environments. The UltraFlex thin film photovoltaic array technology has been targeted to become the sole power system for life support and on-orbit power for the manned Aires Crew Exploration Vehicle. It is therefore, crucial to gain an understanding of the complex charging behavior to answer some of the basic performance and survivability issues in an attempt to ascertain that a single UltraFlex array design will be able to cope with the projected worst case LEO and GEO charging environments. Testing was limited to four array coupons, two coupons each from two different array manufactures, Emcore and Spectrolab. The layout of each array design is identical and varies only in the actual cell technology used. The individual array cells from each manufacturer have an antireflection layered coating and come in two different varieties either uncoated (only AR coating) or coated with a thin conducting ITO layer. The LEO Plasma tests revealed that all four coupons passed the arc threshold -120 V bias tests. GEO electron gun charging tests revealed that only front side area of ITO coated coupons passed tests. Only the Emcore AR array passed backside Stage 2 GEO Tests.

Development of brain PET using GAPD arrays.

PubMed

Jung, Jin Ho; Choi, Yong; Hong, Key Jo; Kang, Jihoon; Hu, Wei; Lim, Hyun Keong; Huh, Yoonsuk; Kim, Sangsu; Jung, Jiwoong; Kim, Kyu Bom

2012-03-01

In recent times, there has been great interest in the use of Geiger-mode avalanche photodiodes (GAPDs) as scintillator readout in positron emission tomography (PET) detectors because of their advantages, such as high gain, compact size, low power consumption, and magnetic field insensitivity. The purpose of this study was to develop a novel PET system based on GAPD arrays for brain imaging. The PET consisted of 72 detector modules arranged in a ring of 330 mm diameter. Each PET module was composed of a 4 × 4 matrix of 3 × 3 × 20 mm(3) cerium-doped lutetium yttrium orthosilicate (LYSO) crystals coupled with a 4 × 4 array three-side tileable GAPD. The signals from each PET module were fed into preamplifiers using a 3 m long flat cable and then sent to a position decoder circuit (PDC), which output a digital address and an analog pulse of the interacted channel among 64 preamplifier signals transmitted from four PET detector modules. The PDC outputs were fed into field programmable gate array (FPGA)-embedded data acquisition (DAQ) boards. The analog signal was then digitized, and arrival time and energy of the signal were calculated and stored. The energy and coincidence timing resolutions measured for 511 keV gamma rays were 18.4 ± 3.1% and 2.6 ns, respectively. The transaxial spatial resolution and sensitivity in the center of field of view (FOV) were 3.1 mm and 0.32% cps/Bq, respectively. The rods down to a diameter of 2.5 mm were resolved in a hot-rod phantom image, and activity distribution patterns between the white and gray matters in the Hoffman brain phantom were well imaged. Experimental results indicate that a PET system can be developed using GAPD arrays and the GAPD-based PET system can provide high-quality PET imaging.

Applicability of the Rayleigh-Gans approximation for scattering by snowflakes at microwave frequencies in vertical incidence

NASA Astrophysics Data System (ADS)

Tyynelä, J.; Leinonen, J.; Westbrook, C. D.; Moisseev, D.; Nousiainen, T.

2013-02-01

The applicability of the Rayleigh-Gans approximation (RGA) for scattering by snowflakes is studied in the microwave region of the electromagnetic spectrum. Both the shapes of the single ice crystals, or monomers, and their amounts in the modeled snowflakes are varied. For reference, the discrete-dipole approximation (DDA) is used to produce numerically accurate solutions to the single-scattering properties, such as the backscattering and extinction cross-sections, single-scattering albedo, and the asymmetry parameter. We find that the single-scattering albedo is the most accurate with only about 10% relative bias at maximum. The asymmetry parameter has about 0.12 absolute bias at maximum. The backscattering and extinction cross-sections show about - 65% relative biases at maximum, corresponding to about - 4.6 dB difference. Overall, the RGA agrees well with the DDA computations for all the cases studied and is more accurate for the integrated quantities, such as the single-scattering albedo and the asymmetry parameter than the cross-sections for the same snowflakes. The accuracy of the RGA seems to improve, when the number of monomers is increased in an aggregate, and decrease, when the frequency increases. It is also more accurate for less dense monomer shapes, such as stellar dendrites. The DDA and RGA results are well correlated; the sample correlation coefficients of those are close to unity throughout the study. Therefore, the accuracy of the RGA could be improved by applying appropriate correction factors.

Scene-based nonuniformity correction technique for infrared focal-plane arrays.

PubMed

Liu, Yong-Jin; Zhu, Hong; Zhao, Yi-Gong

2009-04-20

A scene-based nonuniformity correction algorithm is presented to compensate for the gain and bias nonuniformity in infrared focal-plane array sensors, which can be separated into three parts. First, an interframe-prediction method is used to estimate the true scene, since nonuniformity correction is a typical blind-estimation problem and both scene values and detector parameters are unavailable. Second, the estimated scene, along with its corresponding observed data obtained by detectors, is employed to update the gain and the bias by means of a line-fitting technique. Finally, with these nonuniformity parameters, the compensated output of each detector is obtained by computing a very simple formula. The advantages of the proposed algorithm lie in its low computational complexity and storage requirements and ability to capture temporal drifts in the nonuniformity parameters. The performance of every module is demonstrated with simulated and real infrared image sequences. Experimental results indicate that the proposed algorithm exhibits a superior correction effect.

Least-Squares Self-Calibration of Imaging Array Data

NASA Technical Reports Server (NTRS)

Arendt, R. G.; Moseley, S. H.; Fixsen, D. J.

2004-01-01

When arrays are used to collect multiple appropriately-dithered images of the same region of sky, the resulting data set can be calibrated using a least-squares minimization procedure that determines the optimal fit between the data and a model of that data. The model parameters include the desired sky intensities as well as instrument parameters such as pixel-to-pixel gains and offsets. The least-squares solution simultaneously provides the formal error estimates for the model parameters. With a suitable observing strategy, the need for separate calibration observations is reduced or eliminated. We show examples of this calibration technique applied to HST NICMOS observations of the Hubble Deep Fields and simulated SIRTF IRAC observations.

Superconducting Bolometer Array Architectures

NASA Technical Reports Server (NTRS)

Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Shafer, Rick; Staguhn, Johannes; Wollack, Ed; Oegerle, William (Technical Monitor)

2002-01-01

The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

A novel digital image sensor with row wise gain compensation for Hyper Spectral Imager (HySI) application

NASA Astrophysics Data System (ADS)

Lin, Shengmin; Lin, Chi-Pin; Wang, Weng-Lyang; Hsiao, Feng-Ke; Sikora, Robert

2009-08-01

A 256x512 element digital image sensor has been developed which has a large pixel size, slow scan and low power consumption for Hyper Spectral Imager (HySI) applications. The device is a mixed mode, silicon on chip (SOC) IC. It combines analog circuitry, digital circuitry and optical sensor circuitry into a single chip. This chip integrates a 256x512 active pixel sensor array, a programming gain amplifier (PGA) for row wise gain setting, I2C interface, SRAM, 12 bit analog to digital convertor (ADC), voltage regulator, low voltage differential signal (LVDS) and timing generator. The device can be used for 256 pixels of spatial resolution and 512 bands of spectral resolution ranged from 400 nm to 950 nm in wavelength. In row wise gain readout mode, one can set a different gain on each row of the photo detector by storing the gain setting data on the SRAM thru the I2C interface. This unique row wise gain setting can be used to compensate the silicon spectral response non-uniformity problem. Due to this unique function, the device is suitable for hyper-spectral imager applications. The HySI camera located on-board the Chandrayaan-1 satellite, was successfully launched to the moon on Oct. 22, 2008. The device is currently mapping the moon and sending back excellent images of the moon surface. The device design and the moon image data will be presented in the paper.

A new strategy for array optimization applied to Brazilian Decimetric Array

NASA Astrophysics Data System (ADS)

Faria, C.; Stephany, S.; Sawant, H. S.

Radio interferometric arrays measure the Fourier transform of the sky brightness distribution in a finite set of points that are determined by the cross-correlation of different pairs of antennas of the array The sky brightness distribution is reconstructed by the inverse Fourier transform of the sampled visibilities The quality of the reconstructed images strongly depends on the array configuration since it determines the sampling function and therefore the points in the Fourier Plane This work proposes a new optimization strategy for the array configuration that is based on the entropy of the distribution of the samples points in the Fourier plane A stochastic optimizer the Ant Colony Optimization employs entropy of the point distribution in the Fourier plane to iteratively refine the candidate solutions The proposed strategy was developed for the Brazilian Decimetric Array BDA a radio interferometric array that is currently being developed for solar observations at the Brazilian Institute for Space Research Configurations results corresponding to the Fourier plane coverage synthesized beam and side lobes levels are shown for an optimized BDA configuration obtained with the proposed strategy and compared to the results for a standard T array configuration that was originally proposed

High-resolution array comparative genomic hybridization analysis of human bronchial and salivary adenoid cystic carcinoma.

PubMed

Bernheim, Alain; Toujani, Saloua; Saulnier, Patrick; Robert, Thomas; Casiraghi, Odile; Validire, Pierre; Temam, Stéphane; Menard, Philippe; Dessen, Philippe; Fouret, Pierre

2008-05-01

Adenoid cystic carcinoma (ACC) is a rare but distinctive tumor. Oligonucleotide array comparative genomic hybridization has been applied for cataloging genomic copy number alterations (CNAs) in 17 frozen salivary or bronchial tumors. Only four whole chromosome CNAs were found, and most cases had 2-4 segmental CNAs. No high level amplification was observed. There were recurrent gains at 7p15.2, 17q21-25, and 22q11-13, and recurrent losses at 1p35, 6q22-25, 8q12-13, 9p21, 12q12-13, and 17p11-13. The minimal region of gain at 7p15.2 contained the HOXA cluster. The minimal common regions of deletions contained the CDKN2A/CDKN2B, TP53, and LIMA1 tumor suppressor genes. The recurrent deletion at 8q12.3-13.1 contained no straightforward tumor suppressor gene, but the MIRN124A2 microRNA gene, whose product regulates MMP2 and CDK6. Among unique CNAs, gains harbored CCND1, KIT/PDGFRA/KDR, MDM2, and JAK2. The CNAs involving CCND1, MDM2, KIT, CDKN2A/2B, and TP53 were validated by FISH and/or multiplex ligation-dependent probe amplification. Although most tumors overexpressed cyclin D1 compared with surrounding glands, the only case to overexpress MDM2 had the corresponding CNA. In conclusion, our report suggests that ACC is characterized by a relatively low level of structural complexity. Array CGH and immunohistochemical data implicate MDM2 as the oncogene targeted at 12q15. The gain at 4q12 warrants further exploration as it contains a cluster of receptor kinase genes (KIT/PDGFRA/KDR), whose products can be responsive to specific therapies.

A 32 GHz microstrip array antenna for microspacecraft application

NASA Technical Reports Server (NTRS)

Huang, J.

1994-01-01

JPL/NASA is currently developing microspacecraft systems for future deep space applications. One of the frequency bands being investigated for microspacecraft is the Ka-band (32 GHz), which can be used with smaller equipment and provides a larger bandwidth. This article describes the successful development of a circularly polarized microstrip array with 28 dBic of gain at 32 GHz. This antenna, which is thin, flat, and small, can be surface-mounted onto the microspacecraft and, hence, takes very little volume and mass of the spacecraft. The challenges in developing this antenna are minimizing the microstrip antenna's insertion loss and maintaining a reasonable frequency bandwidth.

Degree-of-Freedom Strengthened Cascade Array for DOD-DOA Estimation in MIMO Array Systems.

PubMed

Yao, Bobin; Dong, Zhi; Zhang, Weile; Wang, Wei; Wu, Qisheng

2018-05-14

In spatial spectrum estimation, difference co-array can provide extra degrees-of-freedom (DOFs) for promoting parameter identifiability and parameter estimation accuracy. For the sake of acquiring as more DOFs as possible with a given number of physical sensors, we herein design a novel sensor array geometry named cascade array. This structure is generated by systematically connecting a uniform linear array (ULA) and a non-uniform linear array, and can provide more DOFs than some exist array structures but less than the upper-bound indicated by minimum redundant array (MRA). We further apply this cascade array into multiple input multiple output (MIMO) array systems, and propose a novel joint direction of departure (DOD) and direction of arrival (DOA) estimation algorithm, which is based on a reduced-dimensional weighted subspace fitting technique. The algorithm is angle auto-paired and computationally efficient. Theoretical analysis and numerical simulations prove the advantages and effectiveness of the proposed array structure and the related algorithm.

Contact CMOS imaging of gaseous oxygen sensor array

PubMed Central

Daivasagaya, Daisy S.; Yao, Lei; Yi Yung, Ka; Hajj-Hassan, Mohamad; Cheung, Maurice C.; Chodavarapu, Vamsy P.; Bright, Frank V.

2014-01-01

We describe a compact luminescent gaseous oxygen (O2) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O2-sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) encapsulated within sol–gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 µW and an average dynamic power of 625 µW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors. PMID:24493909

Contact CMOS imaging of gaseous oxygen sensor array.

PubMed

Daivasagaya, Daisy S; Yao, Lei; Yi Yung, Ka; Hajj-Hassan, Mohamad; Cheung, Maurice C; Chodavarapu, Vamsy P; Bright, Frank V

2011-10-01

We describe a compact luminescent gaseous oxygen (O 2 ) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O 2 -sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp) 3 ] 2+ ) encapsulated within sol-gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 µW and an average dynamic power of 625 µW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors.

Optical Demonstration of a Medical Imaging System with an EMCCD-Sensor Array for Use in a High Resolution Dynamic X-ray Imager

PubMed Central

Qu, Bin; Huang, Ying; Wang, Weiyuan; Sharma, Prateek; Kuhls-Gilcrist, Andrew T.; Cartwright, Alexander N.; Titus, Albert H.; Bednarek, Daniel R.; Rudin, Stephen

2011-01-01

Use of an extensible array of Electron Multiplying CCDs (EMCCDs) in medical x-ray imager applications was demonstrated for the first time. The large variable electronic-gain (up to 2000) and small pixel size of EMCCDs provide effective suppression of readout noise compared to signal, as well as high resolution, enabling the development of an x-ray detector with far superior performance compared to conventional x-ray image intensifiers and flat panel detectors. We are developing arrays of EMCCDs to overcome their limited field of view (FOV). In this work we report on an array of two EMCCD sensors running simultaneously at a high frame rate and optically focused on a mammogram film showing calcified ducts. The work was conducted on an optical table with a pulsed LED bar used to provide a uniform diffuse light onto the film to simulate x-ray projection images. The system can be selected to run at up to 17.5 frames per second or even higher frame rate with binning. Integration time for the sensors can be adjusted from 1 ms to 1000 ms. Twelve-bit correlated double sampling AD converters were used to digitize the images, which were acquired by a National Instruments dual-channel Camera Link PC board in real time. A user-friendly interface was programmed using LabVIEW to save and display 2K × 1K pixel matrix digital images. The demonstration tiles a 2 × 1 array to acquire increased-FOV stationary images taken at different gains and fluoroscopic-like videos recorded by scanning the mammogram simultaneously with both sensors. The results show high resolution and high dynamic range images stitched together with minimal adjustments needed. The EMCCD array design allows for expansion to an M×N array for arbitrarily larger FOV, yet with high resolution and large dynamic range maintained. PMID:23505330

Micromachined electrode array

DOEpatents

Okandan, Murat; Wessendorf, Kurt O.

2007-12-11

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

Developmental gains in visuospatial memory predict gains in mathematics achievement.

PubMed

Li, Yaoran; Geary, David C

2013-01-01

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

Developmental Gains in Visuospatial Memory Predict Gains in Mathematics Achievement

PubMed Central

Li, Yaoran; Geary, David C.

2013-01-01

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning. PMID:23936154

Signal Space Separation Method for a Biomagnetic Sensor Array Arranged on a Flat Plane for Magnetocardiographic Applications: A Computer Simulation Study

PubMed Central

2018-01-01

Although the signal space separation (SSS) method can successfully suppress interference/artifacts overlapped onto magnetoencephalography (MEG) signals, the method is considered inapplicable to data from nonhelmet-type sensor arrays, such as the flat sensor arrays typically used in magnetocardiographic (MCG) applications. This paper shows that the SSS method is still effective for data measured from a (nonhelmet-type) array of sensors arranged on a flat plane. By using computer simulations, it is shown that the optimum location of the origin can be determined by assessing the dependence of signal and noise gains of the SSS extractor on the origin location. The optimum values of the parameters LC and LD, which, respectively, indicate the truncation values of the multipole-order ℓ of the internal and external subspaces, are also determined by evaluating dependences of the signal, noise, and interference gains (i.e., the shield factor) on these parameters. The shield factor exceeds 104 for interferences originating from fairly distant sources. However, the shield factor drops to approximately 100 when calibration errors of 0.1% exist and to 30 when calibration errors of 1% exist. The shielding capability can be significantly improved using vector sensors, which measure the x, y, and z components of the magnetic field. With 1% calibration errors, a vector sensor array still maintains a shield factor of approximately 500. It is found that the SSS application to data from flat sensor arrays causes a distortion in the signal magnetic field, but it is shown that the distortion can be corrected by using an SSS-modified sensor lead field in the voxel space analysis. PMID:29854364

Progressive but Previously Untreated CLL Patients with Greater Array CGH Complexity Exhibit a Less Durable Response to Chemoimmunotherapy

PubMed Central

Kay, Neil E.; Eckel-Passow, Jeanette E.; Braggio, Esteban; VanWier, Scott; Shanafelt, Tait D.; Van Dyke, Daniel L.; Jelinek, Diane F.; Tschumper, Renee C.; Kipps, Thomas; Byrd, John C.; Fonseca, Rafael

2010-01-01

To better understand the implications of genomic instability and outcome in B-cell CLL, we sought to address genomic complexity as a predictor of chemosensitivity and ultimately clinical outcome in this disease. We employed array-based comparative genomic hybridization (aCGH), using a one-million probe array and identified gains and losses of genetic material in 48 patients treated on a chemoimmunotherapy (CIT) clinical trial. We identified chromosomal gain or loss in ≥6% of the patients on chromosomes 3, 8, 9, 10, 11, 12, 13, 14 and 17. Higher genomic complexity, as a mechanism favoring clonal selection, was associated with shorter progression-free survival and predicted a poor response to treatment. Of interest, CLL cases with loss of p53 surveillance showed more complex genomic features and were found both in patients with a 17p13.1 deletion and in the more favorable genetic subtype characterized by the presence of 13q14.1 deletion. This aCGH study adds information on the association between inferior trial response and increasing genetic complexity as CLL progresses. PMID:21156228

One- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems and dual-antenna transceivers

NASA Astrophysics Data System (ADS)

Lin, Yo-Sheng; Hu, Chun-Hao; Chang, Chi-Ho; Tsao, Ping-Chang

2018-06-01

In this work, we demonstrate novel one-dimensional (1D) and two-dimensional (2D) antenna arrays for both microwave wireless power transfer (MWPT) systems and dual-antenna transceivers. The antenna array can be used as the MWPT receiving antenna of an integrated MWPT and Bluetooth (BLE) communication module (MWPT-BLE module) for smart CNC (computer numerical control) spindle incorporated with the cloud computing system SkyMars. The 2D antenna array has n rows of 1 × m 1D array, and each array is composed of multiple (m) differential feeding antenna elements. Each differential feeding antenna element is a differential feeding structure with a microstrip antenna stripe. The stripe length is shorter than one wavelength to minimise the antenna area and to prevent being excited to a high-order mode. That is, the differential feeding antenna element can suppress the even mode. The mutual coupling between the antenna elements can be suppressed, and the isolation between the receiver and the transmitter can be enhanced. An inclination angle of the main beam aligns with the broadside, and the main beam is further concentrated and shrunk at the elevation direction. Moreover, if more differential feeding antenna elements are used, antenna gain and isolation can be further enhanced. The excellent performance of the proposed antenna arrays indicates that they are suitable for both MWPT systems and dual-antenna transceivers.

Multifunctional Polymer Nanofibers: UV Emission, Optical Gain, Anisotropic Wetting, and High Hydrophobicity for Next Flexible Excitation Sources

PubMed Central

2015-01-01

The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures that are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials are desired to feature a number of opto-mechanical properties, including brightness, optical gain for being used in laser devices, flexibility to conform with different lab-on-chip architectures, and tailorable wettability to control and minimize their interaction with ambient humidity and fluids. In this work, we introduce multifunctional, UV-emitting electrospun fibers with both optical gain and greatly enhanced anisotropic hydrophobicity compared to films. Fibers are described by the onset of a composite wetting state, and their arrangement in uniaxial arrays further favors liquid directional control. The low gain threshold, optical losses, plastic nature, flexibility, and stability of these UV-emitting fibers make them interesting for building light-emitting devices and microlasers. Furthermore, the anisotropic hydrophobicity found is strongly synergic with optical properties, reducing interfacial interactions with liquids and enabling smart functional surfaces for droplet microfluidic and wearable applications. PMID:26401889

Gain weighted eigenspace assignment

NASA Technical Reports Server (NTRS)

Davidson, John B.; Andrisani, Dominick, II

1994-01-01

This report presents the development of the gain weighted eigenspace assignment methodology. This provides a designer with a systematic methodology for trading off eigenvector placement versus gain magnitudes, while still maintaining desired closed-loop eigenvalue locations. This is accomplished by forming a cost function composed of a scalar measure of error between desired and achievable eigenvectors and a scalar measure of gain magnitude, determining analytical expressions for the gradients, and solving for the optimal solution by numerical iteration. For this development the scalar measure of gain magnitude is chosen to be a weighted sum of the squares of all the individual elements of the feedback gain matrix. An example is presented to demonstrate the method. In this example, solutions yielding achievable eigenvectors close to the desired eigenvectors are obtained with significant reductions in gain magnitude compared to a solution obtained using a previously developed eigenspace (eigenstructure) assignment method.

Optical Fiber Array Assemblies for Space Flight on the Lunar Reconnaissance Orbiter

NASA Technical Reports Server (NTRS)

Ott, Jelanie; Matuszeski, Adam

2011-01-01

Custom fiber optic bundle array assemblies developed by the Photonics Group at NASA Goddard Space Flight Center were an enabling technology for both the Lunar Orbiter Laser Altimeter (LOLA) and the Laser Ranging (LR) Investigation on the Lunar Reconnaissance Orbiter (LRO) currently in operation. The unique assembly array designs provided considerable decrease in size and weight and met stringent system level requirements. This is the first time optical fiber array bundle assemblies were used in a high performance space flight application. This innovation was achieved using customized Diamond Switzerland AVIM optical connectors. For LOLA, a five fiber array was developed for the receiver telescope to maintain precise alignment for each of the 200/220 micron optical fibers collecting 1,064 nm wavelength light being reflected back from the moon. The array splits to five separate detectors replacing the need for multiple telescopes. An image illustration of the LOLA instrument can be found at the top of the figure. For the laser ranging, a seven-optical-fiber array of 400/440 micron fibers was developed to transmit light from behind the LR receiver telescope located on the end of the high gain antenna system (HGAS). The bundle was routed across two moving gimbals, down the HGAS boom arm, over a deployable mandrel and across the spacecraft to a detector on the LOLA instrument. The routing of the optical fiber bundle and its end locations is identified in the figure. The Laser Ranging array and bundle is currently accepting light at a wavelength of 532 nm sent to the moon from laser stations at Greenbelt MD and other stations around the world to gather precision ranging information from the Earth to the LRO spacecraft. The LR bundle assembly is capable of withstanding temperatures down to -55 C at the connectors, and 20,000 mechanical gimbal cycles at temperatures as cold as -20 C along the length of the seven-fiber bundle (that is packaged into the gimbals). The total

Heterologous, Expression, and Characterization of Thermostable Glucoamylase Derived from Aspergillus flavus NSH9 in Pichia pastoris

PubMed Central

Karim, Kazi Muhammad Rezaul; Hossain, Md. Anowar; Sing, Ngieng Ngui; Mohd Sinang, Fazia; Hussain, Mohd Hasnain Md.; Roslan, Hairul Azman

2016-01-01

A novel thermostable glucoamylase cDNA without starch binding domain (SBD) of Aspergillus flavus NSH9 was successfully identified, isolated, and overexpressed in Pichia pastoris GS115. The complete open reading frame of glucoamylase from Aspergillus flavus NSH9 was identified by employing PCR that encodes 493 amino acids lacking in the SBD. The first 17 amino acids were presumed to be a signal peptide. The cDNA was cloned into Pichia pastoris and the highest expression of recombinant glucoamylase (rGA) was observed after 8 days of incubation period with 1% methanol. The molecular weight of the purified rGA was about 78 kDa and exhibited optimum catalytic activity at pH 5.0 and temperature of 70°C. The enzyme was stable at higher temperature with 50% of residual activity observed after 20 min at 90°C and 100°C. Low concentration of metal (Mg++, Fe++, Zn++, Cu++, and Pb++) had positive effect on rGA activity. This rGA has the potential for use and application in the saccharification steps, due to its thermostability, in the starch processing industries. PMID:27504454

A Meta-Surface Antenna Array Decoupling (MAAD) Method for Mutual Coupling Reduction in a MIMO Antenna System.

PubMed

Wang, Ziyang; Zhao, Luyu; Cai, Yuanming; Zheng, Shufeng; Yin, Yingzeng

2018-02-16

In this paper, a method to reduce the inevitable mutual coupling between antennas in an extremely closely spaced two-element MIMO antenna array is proposed. A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling. The meta-surface is equivalent to a negative permeability medium, along which wave propagation is rejected. By properly designing the rejection frequency band of the SRR unit, the mutual coupling between the antenna elements in the MIMO antenna system can be significantly reduced. Two prototypes of microstrip antenna arrays at 5.8 GHz band with and without the metasurface have been fabricated and measured. The matching bandwidths of antennas with reflection coefficient smaller than -15 dB for the arrays without and with the metasurface are 360 MHz and 900 MHz respectively. Using the meta-surface, the isolation between elements is increased from around 8 dB to more than 27 dB within the band of interest. Meanwhile, the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are also improved by considerable amounts. All the results demonstrate that the proposed method is very efficient for enhancing the performance of MIMO antenna arrays.

STS-31 Hubble Space Telescope (HST) solar array (SA) deploy aboard OV-103

NASA Image and Video Library

1990-04-25

During STS-31, the Hubble Space Telescope (HST) is held in appendage deploy position by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) above the payload bay (PLB) and crew compartment cabin. While in this position the solar array (SA) wing bistem cassette (HST center) is deployed from its stowed location along side the Support System Module (SSM) forward shell. A high gain antenna (HGA) remains stowed along the SSM. The Earth's surface and the Earth limb creates a dramatic backdrop.

On the acoustic radiation modes of compact regular polyhedral arrays of independent loudspeakers.

PubMed

Pasqual, Alexander Mattioli; Martin, Vincent

2011-09-01

Compact spherical loudspeaker arrays can be used to provide control over their directivity pattern. Usually, this is made by adjusting the gains of preprogrammed spatial filters corresponding to a finite set of spherical harmonics, or to the acoustic radiation modes of the loudspeaker array. Unlike the former, the latter are closely related to the radiation efficiency of the source and span the subspace of the directivities it can produce. However, the radiation modes depend on frequency for arbitrary distributions of transducers on the sphere, which yields complex directivity filters. This work focuses on the most common loudspeaker array configurations, those following the regular shape of the Platonic solids. It is shown that the radiation modes of these sources are frequency independent, and simple algebraic expressions are derived for their radiation efficiencies. In addition, since such modes are vibration patterns driven by electrical signals, the transduction mechanism of compact multichannel sources is also investigated, which is an important issue, especially if the transducers interact inside a shared cabinet. For Platonic solid loudspeakers, it is shown that the common enclosure does not lead to directivity filters that depend on frequency. © 2011 Acoustical Society of America

Solid-state Image Sensor with Focal-plane Digital Photon-counting Pixel Array

NASA Technical Reports Server (NTRS)

Fossum, Eric R.; Pain, Bedabrata

1997-01-01

A solid-state focal-plane imaging system comprises an NxN array of high gain. low-noise unit cells. each unit cell being connected to a different one of photovoltaic detector diodes, one for each unit cell, interspersed in the array for ultra low level image detection and a plurality of digital counters coupled to the outputs of the unit cell by a multiplexer(either a separate counter for each unit cell or a row of N of counters time shared with N rows of digital counters). Each unit cell includes two self-biasing cascode amplifiers in cascade for a high charge-to-voltage conversion gain (greater than 1mV/e(-)) and an electronic switch to reset input capacitance to a reference potential in order to be able to discriminate detection of an incident photon by the photoelectron (e(-))generated in the detector diode at the input of the first cascode amplifier in order to count incident photons individually in a digital counter connected to the output of the second cascade amplifier. Reseting the input capacitance and initiating self-biasing of the amplifiers occurs every clock cycle of an integratng period to enable ultralow light level image detection by the may of photovoltaic detector diodes under such ultralow light level conditions that the photon flux will statistically provide only a single photon at a time incident on anyone detector diode during any clock cycle.

Abstract - Cooperative Research and Development Agreement between Oxergy, Inc. and National Energy Technology Laboratory

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

Chorpening, Benjamin T.; Kamler, Jonathan

The Raman Gas Analyzer (RGA) has been demonstrated to have an extremely fast response (<1 second), pressurized, multi-gas analysis capability. All but the noble gases are Raman active, although the Raman interaction is weak. The RGA uses a reflectively lined capillary as the optical cell, providing both a small sample volume for fast gas exchange, and a much greater Raman signal collection than traditional instrument configurations.

GaAs MMIC elements in phased-array antennas

NASA Technical Reports Server (NTRS)

Leonard, Regis F.

1988-01-01

Over the last six years NASA Lewis Research Center has carried out a program aimed at the development of advanced monolithic microwave integrated circuit technology, principally for use in phased-array antenna applications. Arising out of the Advanced Communications Technology Satellite (ACTS) program, the initial targets of the program were chips which operated at 30 and 20 GHz. Included in this group of activities were monolithic power modules with an output of 2 watts at GHz, variable phase shifters at both 20 and 30 GHz, low noise technology at 30 GHz, and a fully integrated (phase shifter, variable gain amplifier, power amplifier) transmit module at 20 GHz. Subsequent developments are centered on NASA mission requirements, particularly Space Station communications systems and deep space data communications.

Millimeter-wave pseudomorphic HEMT MMIC phased array components for space communications

NASA Technical Reports Server (NTRS)

Lan, G. L.; Pao, C. K.; Wu, C. S.; Mandolia, G.; Hu, M.; Yuan, S.; Leonard, Regis

1991-01-01

Recent advances in pseudomorphic HEMT MMIC (PMHEMT/MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. This paper describes the development of PMHEMT/MMIC components at Ka-band and V-band. Specifically, the following PMHEMT/MMIC components will be described: power amplifiers at Ka-band; power amplifiers at V-band; and four-bit phase shifters at V-band. For the Ka-band amplifier, 125 mW output power with 5.5 dB gain and 21 percent power added efficiency at 2 dB compression point has been achieved. For the V-band amplifier, 112 mW output power with 6 dB gain and 26 percent power added efficiency has been achieved. And, for the V-band phase shifter, four-bit (45 deg steps) phase shifters with less than 8 dB insertion loss from 61 GHz to 63 GHz will be described.

Rate equation analysis and non-Hermiticity in coupled semiconductor laser arrays

NASA Astrophysics Data System (ADS)

Gao, Zihe; Johnson, Matthew T.; Choquette, Kent D.

2018-05-01

Optically coupled semiconductor laser arrays are described by coupled rate equations. The coupled mode equations and carrier densities are included in the analysis, which inherently incorporate the carrier-induced nonlinearities including gain saturation and amplitude-phase coupling. We solve the steady-state coupled rate equations and consider the cavity frequency detuning and the individual laser pump rates as the experimentally controlled variables. We show that the carrier-induced nonlinearities play a critical role in the mode control, and we identify gain contrast induced by cavity frequency detuning as a unique mechanism for mode control. Photon-mediated energy transfer between cavities is also discussed. Parity-time symmetry and exceptional points in this system are studied. Unbroken parity-time symmetry can be achieved by judiciously combining cavity detuning and unequal pump rates, while broken symmetry lies on the boundary of the optical locking region. Exceptional points are identified at the intersection between broken symmetry and unbroken parity-time symmetry.

Enteropathy-associated T-cell lymphoma--a clinicopathologic and array comparative genomic hybridization study.

PubMed

Ko, Young Hyeh; Karnan, Sivasundaram; Kim, Kyeong Mee; Park, Cheol Keun; Kang, Eun Suk; Kim, Young Ho; Kang, Won Ki; Kim, Seok Jin; Kim, Won Seog; Lee, Woo Yong; Chun, Ho Kyung; Seto, Masao

2010-09-01

According to the new World Health Organization classification system, there are 2 types of enteropathy-associated T-cell lymphoma. Type 1 is associated with celiac disease and accounts for the majority of cases in Western countries, whereas type 2 is not associated with celiac disease. To characterize enteropathy-associated T-cell lymphoma types in Korea, we carried out clinicopathologic and immunophenotypic analyses of 8 Koreans with enteropathy-associated T-cell lymphoma and investigated genomic profile using array comparative genomic hybridization. The tumors involved the small intestine in 5 patients and the colorectum in 3 patients. Two patients carried an HLA DQB10302 allele that corresponds to HLA DQ8. None of the patients had gluten-sensitive malabsorption syndrome. Intraepithelial lymphocytosis was observed in all patients. The sizes of the tumor cells were small or small-to-medium in 7 cases and medium-to-large in 1 case. The immunophenotypes of the tumor cells were CD4-CD8+CD56+ in 4 cases, CD4-CD8+CD56- in 1 case, CD4-CD8-CD56+ in 2 cases, and CD4-CD8-CD56- in 1 case. Array comparative genomic hybridization analysis showed that chromosome 9q33-q34.1 gain was present in 4 (80%) of the 5 cases examined. Other recurrent genomic alterations were gain of 6p21.1-21.31 (3/5, 60%), gain of 19q (2/5), and the loss of 3p12.1-p12.2 (2/5) and 3q26.31 (2/5). These results suggest that the most prevalent type of enteropathy-associated T-cell lymphoma in this geographic region is type 2, and the genetic changes associated with it are similar to those in Western countries. Copyright 2010 Elsevier Inc. All rights reserved.

Multi-parameter Nonlinear Gain Correction of X-ray Transition Edge Sensors for the X-ray Integral Field Unit

NASA Astrophysics Data System (ADS)

Cucchetti, E.; Eckart, M. E.; Peille, P.; Porter, F. S.; Pajot, F.; Pointecouteau, E.

2018-04-01

With its array of 3840 Transition Edge Sensors (TESs), the Athena X-ray Integral Field Unit (X-IFU) will provide spatially resolved high-resolution spectroscopy (2.5 eV up to 7 keV) from 0.2 to 12 keV, with an absolute energy scale accuracy of 0.4 eV. Slight changes in the TES operating environment can cause significant variations in its energy response function, which may result in systematic errors in the absolute energy scale. We plan to monitor such changes at pixel level via onboard X-ray calibration sources and correct the energy scale accordingly using a linear or quadratic interpolation of gain curves obtained during ground calibration. However, this may not be sufficient to meet the 0.4 eV accuracy required for the X-IFU. In this contribution, we introduce a new two-parameter gain correction technique, based on both the pulse-height estimate of a fiducial line and the baseline value of the pixels. Using gain functions that simulate ground calibration data, we show that this technique can accurately correct deviations in detector gain due to changes in TES operating conditions such as heat sink temperature, bias voltage, thermal radiation loading and linear amplifier gain. We also address potential optimisations of the onboard calibration source and compare the performance of this new technique with those previously used.

Two-dimensional photon-counting detector arrays based on microchannel array plates

NASA Technical Reports Server (NTRS)

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

1975-01-01

The production of simple and rugged photon-counting detector arrays has been made possible by recent improvements in the performance of the microchannel array plate (MCP) and by the parallel development of compatible electronic readout systems. The construction of proximity-focused MCP arrays of novel design in which photometric information from (n x m) picture elements is read out with a total of (n + m) amplifier and discriminator circuits is described. Results obtained with a breadboard (32 x 32)-element array employing 64 charge-sensitive amplifiers are presented, and the application of systems of this type in spectrometers and cameras for use with ground-based telescopes and on orbiting spacecraft discussed.

Developments of FPGA-based digital back-ends for low frequency antenna arrays at Medicina radio telescopes

NASA Astrophysics Data System (ADS)

Naldi, G.; Bartolini, M.; Mattana, A.; Pupillo, G.; Hickish, J.; Foster, G.; Bianchi, G.; Lingua, A.; Monari, J.; Montebugnoli, S.; Perini, F.; Rusticelli, S.; Schiaffino, M.; Virone, G.; Zarb Adami, K.

In radio astronomy Field Programmable Gate Array (FPGA) technology is largely used for the implementation of digital signal processing techniques applied to antenna arrays. This is mainly due to the good trade-off among computing resources, power consumption and cost offered by FPGA chip compared to other technologies like ASIC, GPU and CPU. In the last years several digital backend systems based on such devices have been developed at the Medicina radio astronomical station (INAF-IRA, Bologna, Italy). Instruments like FX correlator, direct imager, beamformer, multi-beam system have been successfully designed and realized on CASPER (Collaboration for Astronomy Signal Processing and Electronics Research, https://casper.berkeley.edu) processing boards. In this paper we present the gained experience in this kind of applications.

Optical Characteristics of Vertical Cavity Surface Emitting Lasers and Two Dimensional Coherently Coupled Arrays.

NASA Astrophysics Data System (ADS)

Catchmark, Jeffrey Michael

1995-01-01

The following describes extensive experimental and theoretical research concerning the optical, electrical and thermal characteristics of GaAs/AlGaAs vertical cavity surface emitting lasers (VCSELs) and coherently coupled two dimensional VCSEL arrays grown by molecular beam epitaxy. The temperature and wavelength performance of VCSELs containing various epitaxial designs is discussed in detail. By employing a high barrier confinement spacer region and by blue shifting the optical gain with respect to the Fabry Perot transmission wavelength, greater than 150^circ rm C continuous wave operation was obtained. This is accomplished while maintaining a variation in the threshold current of only +/-0.93mA over a temperature range of 150^circrm C. This exceptional performance is achieved while attaining a minimum threshold current of approximately 4.3mA at 75^circrm C. In addition, the optical characteristics of multi-transverse mode VCSEL arrays are examined experimentally. A total of nine transverse modes have been identified and are found to couple coherently into distinct array modes. While operating in higher order transverse modes, a record 1.4W (pulsed) of optical power is obtained from a 15 x 15 VCSEL array. Array mode formation in coherently coupled VCSEL arrays is also examined theoretically. A numerical model is developed to describe the formation of supermodes in reflectivity modulated VCSEL arrays. Using this model, the effects of depth of reflectivity modulation, cavity length, window size and grid size on mode formation are explored. The array modes predicted by this model are in agreement with those observed experimentally. Analytic models will also be presented describing the effects of thermally induced waveguiding on the optical characteristics of VCSELs operating in the fundamental transverse mode. A thermal waveguide is found to have a significant effect on the spot size and radius of curvature of the phase of the fundamental optical mode. In addition

High resolution beamforming on large aperture vertical line arrays: Processing synthetic data

NASA Astrophysics Data System (ADS)

Tran, Jean-Marie Q.; Hodgkiss, William S.

1990-09-01

This technical memorandum studies the beamforming of large aperture line arrays deployed vertically in the water column. The work concentrates on the use of high resolution techniques. Two processing strategies are envisioned: (1) full aperture coherent processing which offers in theory the best processing gain; and (2) subaperture processing which consists in extracting subapertures from the array and recombining the angular spectra estimated from these subarrays. The conventional beamformer, the minimum variance distortionless response (MVDR) processor, the multiple signal classification (MUSIC) algorithm and the minimum norm method are used in this study. To validate the various processing techniques, the ATLAS normal mode program is used to generate synthetic data which constitute a realistic signals environment. A deep-water, range-independent sound velocity profile environment, characteristic of the North-East Pacific, is being studied for two different 128 sensor arrays: a very long one cut for 30 Hz and operating at 20 Hz; and a shorter one cut for 107 Hz and operating at 100 Hz. The simulated sound source is 5 m deep. The full aperture and subaperture processing are being implemented with curved and plane wavefront replica vectors. The beamforming results are examined and compared to the ray-theory results produced by the generic sonar model.

Replica amplification of nucleic acid arrays

DOEpatents

Church, George M.; Mitra, Robi D.

2010-08-31

Disclosed are improved methods of making and using immobilized arrays of nucleic acids, particularly methods for producing replicas of such arrays. Included are methods for producing high density arrays of nucleic acids and replicas of such arrays, as well as methods for preserving the resolution of arrays through rounds of replication. Also included are methods which take advantage of the availability of replicas of arrays for increased sensitivity in detection of sequences on arrays. Improved methods of sequencing nucleic acids immobilized on arrays utilizing single copies of arrays and methods taking further advantage of the availability of replicas of arrays are disclosed. The improvements lead to higher fidelity and longer read lengths of sequences immobilized on arrays. Methods are also disclosed which improve the efficiency of multiplex PCR using arrays of immobilized nucleic acids.

ISS Solar Array Management

NASA Technical Reports Server (NTRS)

Williams, James P.; Martin, Keith D.; Thomas, Justin R.; Caro, Samuel

2010-01-01

The International Space Station (ISS) Solar Array Management (SAM) software toolset provides the capabilities necessary to operate a spacecraft with complex solar array constraints. It monitors spacecraft telemetry and provides interpretations of solar array constraint data in an intuitive manner. The toolset provides extensive situational awareness to ensure mission success by analyzing power generation needs, array motion constraints, and structural loading situations. The software suite consists of several components including samCS (constraint set selector), samShadyTimers (array shadowing timers), samWin (visualization GUI), samLock (array motion constraint computation), and samJet (attitude control system configuration selector). It provides high availability and uptime for extended and continuous mission support. It is able to support two-degrees-of-freedom (DOF) array positioning and supports up to ten simultaneous constraints with intuitive 1D and 2D decision support visualizations of constraint data. Display synchronization is enabled across a networked control center and multiple methods for constraint data interpolation are supported. Use of this software toolset increases flight safety, reduces mission support effort, optimizes solar array operation for achieving mission goals, and has run for weeks at a time without issues. The SAM toolset is currently used in ISS real-time mission operations.

Material Outgassing, Identification and Deposition, MOLIDEP System

NASA Technical Reports Server (NTRS)

Scialdone, John J.; Montoya, Alex F.

2002-01-01

The outgassing tests are performed employing a modified vacuum operated Cahn analytical microbalance, identified as the MOLIDEP system. The test measures under high vacuum, the time varying Molecular mass loss of a material sample held at a chosen temperature; it Identifies the outgassing molecular components using an inline SRS 300 amu Residual Gas Analyzer (RGA) and employs a temperature controlled 10 MHz Quartz Crystal Microbalance (QCM) to measure the condensable DEPosits. Both the QCM and the RGA intercept within the conductive passage the outgassing products being evacuated by a turbomolecular pump. The continuous measurements of the mass loss, the rate of loss, the sample temperature, the rate of temperature change, the QCM temperature and the QCM recorded condensable deposits or rate of deposits are saved to an Excel spreadsheet. A separate computer controls the RGA.

Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

NASA Astrophysics Data System (ADS)

Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Vandenbosch, Guy A. E.; Narbudowicz, Adam

2017-01-01

A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

A discrete component low-noise preamplifier readout for a linear (1×16) SiC photodiode array

NASA Astrophysics Data System (ADS)

Kahle, Duncan; Aslam, Shahid; Herrero, Federico A.; Waczynski, Augustyn

2016-09-01

A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1×16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analog signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

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.

A Discrete Component Low-Noise Preamplifier Readout for a Linear (1x16) SiC Photodiode Array

NASA Technical Reports Server (NTRS)

Kahle, Duncan; Aslam, Shahid; Herrero, Frederico A.; Waczynski, Augustyn

2016-01-01

A compact, low-noise and inexpensive preamplifier circuit has been designed and fabricated to optimally readout a common cathode (1x16) channel 4H-SiC Schottky photodiode array for use in ultraviolet experiments. The readout uses an operational amplifier with 10 pF capacitor in the feedback loop in parallel with a low leakage switch for each of the channels. This circuit configuration allows for reiterative sample, integrate and reset. A sampling technique is given to remove Johnson noise, enabling a femtoampere level readout noise performance. Commercial-off-the-shelf acquisition electronics are used to digitize the preamplifier analogue signals. The data logging acquisition electronics has a different integration circuit, which allows the bandwidth and gain to be independently adjusted. Using this readout, photoresponse measurements across the array between spectral wavelengths 200 nm and 370 nm are made to establish the array pixels external quantum efficiency, current responsivity and noise equivalent power.

Passive microfluidic array card and reader

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

Dugan, Lawrence Christopher; Coleman, Matthew A

A microfluidic array card and reader system for analyzing a sample. The microfluidic array card includes a sample loading section for loading the sample onto the microfluidic array card, a multiplicity of array windows, and a transport section or sections for transporting the sample from the sample loading section to the array windows. The microfluidic array card reader includes a housing, a receiving section for receiving the microfluidic array card, a viewing section, and a light source that directs light to the array window of the microfluidic array card and to the viewing section.

Microlens array processor with programmable weight mask and direct optical input

NASA Astrophysics Data System (ADS)

Schmid, Volker R.; Lueder, Ernst H.; Bader, Gerhard; Maier, Gert; Siegordner, Jochen

1999-03-01

We present an optical feature extraction system with a microlens array processor. The system is suitable for online implementation of a variety of transforms such as the Walsh transform and DCT. Operating with incoherent light, our processor accepts direct optical input. Employing a sandwich- like architecture, we obtain a very compact design of the optical system. The key elements of the microlens array processor are a square array of 15 X 15 spherical microlenses on acrylic substrate and a spatial light modulator as transmissive mask. The light distribution behind the mask is imaged onto the pixels of a customized a-Si image sensor with adjustable gain. We obtain one output sample for each microlens image and its corresponding weight mask area as summation of the transmitted intensity within one sensor pixel. The resulting architecture is very compact and robust like a conventional camera lens while incorporating a high degree of parallelism. We successfully demonstrate a Walsh transform into the spatial frequency domain as well as the implementation of a discrete cosine transform with digitized gray values. We provide results showing the transformation performance for both synthetic image patterns and images of natural texture samples. The extracted frequency features are suitable for neural classification of the input image. Other transforms and correlations can be implemented in real-time allowing adaptive optical signal processing.

Design of diffractive microlens array integration with focal plane arrays

NASA Astrophysics Data System (ADS)

Chen, Sihai; Yi, Xinjian; Li, Yi; He, Miao; Chen, Sixiang; Kong, Lingbin

2000-10-01

The IR spectrum from 3 to 5micrometers has numerous applications in both military and civil industries. High performance at high operating temperature is often important in these applications. Conventional Focal Plane Arrays (FPAs) without integration with concentrator such as microlens have poor sensitivity and low signal-to-noise ratio because of their lower fill factor. The binary optics microlens arrays reported in this paper are designed for integration with FPAs. Thus, the FPAs' fill factor, sensitivity, and signal- to-noise ratio can be improved while retaining a given image resolution and optical collection area. In the paper, we discussed the 256(Horizontal)x290(Vertical) microlens arrays designed for a center wavelength of 4micrometers , with 50micrometers (Horizontalx33micrometers (Vertical) quadrate pixel dimension and a speed (F number) of F/1.96. PtSi FPAs were fabricated on the front side of a 400-micrometers -thick Si substrate. The designed diffractive microlens arrays will be etched on the back side of the same wafer in a register fashion and it will be reported in other paper. Considering the diffraction efficiency, 8-phase-level approximation is enough. For the diffraction efficiency of 8-phase-level diffractive microlens reaches 95%. The process only need three mask-level, so we designed and fabricated three masks with the same dimension 4'x4'. Also, a set of fine verniers was designed and fabricated on each mask to allow accurate alignment during the fabrication process. Through a computer simulation, the microlens arrays are nearly diffraction limited, with the diffraction efficiency of 93%, a bit lower than the theoretical value of 95%. Introduction of microlens arrays has the ability to increase the FPAs' fill factor to 100%, while it is only about 21.6% without microlens. To our knowledge, this is the first trial of integration large area microlens arrays with FPAs at home.

Signal detectability in diffusive media using phased arrays in conjunction with detector arrays.

PubMed

Kang, Dongyel; Kupinski, Matthew A

2011-06-20

We investigate Hotelling observer performance (i.e., signal detectability) of a phased array system for tasks of detecting small inhomogeneities and distinguishing adjacent abnormalities in uniform diffusive media. Unlike conventional phased array systems where a single detector is located on the interface between two sources, we consider a detector array, such as a CCD, on a phantom exit surface for calculating the Hotelling observer detectability. The signal detectability for adjacent small abnormalities (2 mm displacement) for the CCD-based phased array is related to the resolution of reconstructed images. Simulations show that acquiring high-dimensional data from a detector array in a phased array system dramatically improves the detectability for both tasks when compared to conventional single detector measurements, especially at low modulation frequencies. It is also observed in all studied cases that there exists the modulation frequency optimizing CCD-based phased array systems, where detectability for both tasks is consistently high. These results imply that the CCD-based phased array has the potential to achieve high resolution and signal detectability in tomographic diffusive imaging while operating at a very low modulation frequency. The effect of other configuration parameters, such as a detector pixel size, on the observer performance is also discussed.

A Phase Correction Technique Based on Spatial Movements of Antennas in Real-Time (S.M.A.R.T.) for Designing Self-Adapting Conformal Array Antennas

NASA Astrophysics Data System (ADS)

Roy, Sayan

This research presents a real-time adaptive phase correction technique for flexible phased array antennas on conformal surfaces of variable shapes. Previously reported pattern correctional methods for flexible phased array antennas require prior knowledge on the possible non-planar shapes in which the array may adapt for conformal applications. For the first time, this initial requirement of shape curvature knowledge is no longer needed and the instantaneous information on the relative location of array elements is used here for developing a geometrical model based on a set of Bezier curves. Specifically, by using an array of inclinometer sensors and an adaptive phase-correctional algorithm, it has been shown that the proposed geometrical model can successfully predict different conformal orientations of a 1-by-4 antenna array in real-time without the requirement of knowing the shape-changing characteristics of the surface the array is attached upon. Moreover, the phase correction technique is validated by determining the field patterns and broadside gain of the 1-by-4 antenna array on four different conformal surfaces with multiple points of curvatures. Throughout this work, measurements are shown to agree with the analytical solutions and full-wave simulations.

Micromirror Array Control of a Phase-Locked Laser Diode Array

DTIC Science & Technology

1995-12-01

Micromirror Intensity-Voltage Curve . From the intensity plot, maxima (Ix) and minima (IMN) are noted. If IMAX and IMn are known, A4 can be calculated for...of the micromirror array used. Mirror 9 600 500 E 400- S300- C, -0200 lOO_ 0 0 5 10 15 20 25 30 Volts Figure 3b. Mirror Deflection Curve Corresponding...AFIT/GAP/ENP/95D-2 MICROMIRROR ARRAY CONTROL OF A PHASE-LOCKED LASER DIODE ARRAY THESIS Carl J. Christensen, Captain, USAF AFIT/GAP/ENP/95D-2

NaI(Tl) scintillator read out with SiPM array for gamma spectrometer

NASA Astrophysics Data System (ADS)

Huang, Tuchen; Fu, Qibin; Lin, Shaopeng; Wang, Biao

2017-04-01

The NaI(Tl) scintillator is widely used in gamma spectrometer with photomultiplier tube (PMT) readout. Recently developed silicon photomultiplier (SiPM) offers gain and efficiency similar to those of PMT, but with merits such as low bias voltage, compact volume, low cost, high ruggedness and magnetic resonance compatibility. In this study, 2-in. and 1-in. NaI(Tl) scintillators were readout with SiPM arrays, which were made by tiling multiple SiPMs each with an active area of 6×6 mm2 on a printed circuit board. The energy resolutions for 661.6 keV gamma rays, obtained with Φ2×2 in. scintillator coupled to 6×6 ch SiPM array and Φ1×1 in. scintillator coupled to 4×4 ch SiPM array were 7.6% and 7.8%, respectively, and were very close to the results obtained with traditional bialkali PMT (7.3% and 7.6%, respectively). Scintillator coupled to photodetector with smaller area was also studied by adding a light guide or using scintillator with tapered head. The latter showed better performance than using light guide. The 1-in. NaI(Tl) scintillator with tapered head coupled to 2×2 ch SiPM array achieved 7.7% energy resolution at 661.6 keV, the same as that obtained with standard Φ1×1 in. scintillator coupled to 4×4 ch SiPM array. While the 2-in. scintillator with similar geometry showed degraded energy resolution, 10.2% at 661.6 keV, but could still be used when high efficiency is preferred over energy resolution.

Comparing gains and losses.

PubMed

McGraw, A Peter; Larsen, Jeff T; Kahneman, Daniel; Schkade, David

2010-10-01

Loss aversion in choice is commonly assumed to arise from the anticipation that losses have a greater effect on feelings than gains, but evidence for this assumption in research on judged feelings is mixed. We argue that loss aversion is present in judged feelings when people compare gains and losses and assess them on a common scale. But many situations in which people judge and express their feelings lack these features. When judging their feelings about an outcome, people naturally consider a context of similar outcomes for comparison (e.g., they consider losses against other losses). This process permits gains and losses to be normed separately and produces psychological scale units that may not be the same in size or meaning for gains and losses. Our experiments show loss aversion in judged feelings for tasks that encourage gain-loss comparisons, but not tasks that discourage them, particularly those using bipolar scales.

Axiom turkey genotyping array

USDA-ARS?s Scientific Manuscript database

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

Carbon nanotube nanoelectrode arrays

DOEpatents

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

2008-11-18

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

High density pixel array and laser micro-milling method for fabricating array

NASA Technical Reports Server (NTRS)

McFall, James Earl (Inventor); Wiener-Avnear, Eliezer (Inventor)

2003-01-01

A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

Association, effects and validation of polymorphisms within the NCAPG - LCORL locus located on BTA6 with feed intake, gain, meat and carcass traits in beef cattle

USDA-ARS?s Scientific Manuscript database

Background: In a previously reported genome-wide association study based on a high-density bovine SNP genotyping array, 8 SNP were nominally associated (Pgain (ADG) and 3 of these were also associated (P

Calibration artefacts in radio interferometry - II. Ghost patterns for irregular arrays

NASA Astrophysics Data System (ADS)

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

2016-04-01

Calibration artefacts, like the self-calibration bias, usually emerge when data are calibrated using an incomplete sky model. In the first paper of this series, in which we analysed calibration artefacts in data from the Westerbork Synthesis Radio Telescope, we showed that these artefacts take the form of spurious positive and negative sources, which we refer to as ghosts or ghost sources. We also developed a mathematical framework with which we could predict the ghost pattern of an east-west interferometer for a simple two-source test case. In this paper, we extend our analysis to more general array layouts. This provides us with a useful method for the analysis of ghosts that we refer to as extrapolation. Combining extrapolation with a perturbation analysis, we are able to (1) analyse the ghost pattern for a two-source test case with one modelled and one unmodelled source for an arbitrary array layout, (2) explain why some ghosts are brighter than others, (3) define a taxonomy allowing us to classify the different ghosts, (4) derive closed form expressions for the fluxes and positions of the brightest ghosts, and (5) explain the strange two-peak structure with which some ghosts manifest during imaging. We illustrate our mathematical predictions using simulations of the KAT-7 (seven-dish Karoo Array Telescope) array. These results show the explanatory power of our mathematical model. The insights gained in this paper provide a solid foundation to study calibration artefacts in arbitrary, I.e. more complicated than the two-source example discussed here, incomplete sky models or full synthesis observations including direction-dependent effects.

Photosensitive biosensor array system using optical addressing without an addressing circuit on array biochips

NASA Astrophysics Data System (ADS)

Ahn, Chang-Geun; Ah, Chil Seong; Kim, Tae-Youb; Park, Chan Woo; Yang, Jong-Heon; Kim, Ansoon; Sung, Gun Yong

2010-09-01

This paper introduces a photosensitive biosensor array system with a simple photodiode array that detects photocurrent changes caused by reactions between probe and target molecules. Using optical addressing, the addressing circuit on the array chip is removed for low-cost application, and real cell addressing is achieved using an externally located computer-controllable light-emitting diode array module. The fabricated biosensor array chip shows a good dynamic range of 1-100 ng/mL under prostate-specific antigen detection, with an on-chip resolution of roughly 1 ng/mL.

The CHARA Array Database

NASA Astrophysics Data System (ADS)

Jones, Jeremy; Schaefer, Gail; ten Brummelaar, Theo; Gies, Douglas; Farrington, Christopher

2018-01-01

We are building a searchable database for the CHARA Array data archive. The Array consists of six telescopes linked together as an interferometer, providing sub-milliarcsecond resolution in the optical and near-infrared. The Array enables a variety of scientific studies, including measuring stellar angular diameters, imaging stellar shapes and surface features, mapping the orbits of close binary companions, and resolving circumstellar environments. This database is one component of an NSF/MSIP funded program to provide open access to the CHARA Array to the broader astronomical community. This archive goes back to 2004 and covers all the beam combiners on the Array. We discuss the current status of and future plans for the public database, and give directions on how to access it.

Novel Implementations of Wideband Tightly Coupled Dipole Arrays for Wide-Angle Scanning

NASA Astrophysics Data System (ADS)

Yetisir, Ersin

components, including the FSS, radiating dipoles and the feed lines are placed on the same PCB, vertically oriented over the array ground plane, resulting in a low-cost and light-weight structure. The effects of finite aperture sizes in presence of FSS or dielectric superstrates are also considered. Specifically, we compare the performance of finite TCDAs with FSS or dielectric loading. The performance metric is beam pointing accuracy for moderate array sizes ( 30dBi gain) with various edge element terminations. It is shown that even terminating two unit cells at the array edges can provide effective suppression of edge-born waves and achieve excellent beam accuracy. This is the case when both the FSS elements and radiating dipoles are resistively loaded in the unit-cells along the aperture edges.

The Applicability of Incoherent Array Processing to IMS Seismic Array Stations

NASA Astrophysics Data System (ADS)

Gibbons, S. J.

2012-04-01

The seismic arrays of the International Monitoring System for the CTBT differ greatly in size and geometry, with apertures ranging from below 1 km to over 60 km. Large and medium aperture arrays with large inter-site spacings complicate the detection and estimation of high frequency phases since signals are often incoherent between sensors. Many such phases, typically from events at regional distances, remain undetected since pipeline algorithms often consider only frequencies low enough to allow coherent array processing. High frequency phases that are detected are frequently attributed qualitatively incorrect backazimuth and slowness estimates and are consequently not associated with the correct event hypotheses. This can lead to missed events both due to a lack of contributing phase detections and by corruption of event hypotheses by spurious detections. Continuous spectral estimation can be used for phase detection and parameter estimation on the largest aperture arrays, with phase arrivals identified as local maxima on beams of transformed spectrograms. The estimation procedure in effect measures group velocity rather than phase velocity and the ability to estimate backazimuth and slowness requires that the spatial extent of the array is large enough to resolve time-delays between envelopes with a period of approximately 4 or 5 seconds. The NOA, AKASG, YKA, WRA, and KURK arrays have apertures in excess of 20 km and spectrogram beamforming on these stations provides high quality slowness estimates for regional phases without additional post-processing. Seven arrays with aperture between 10 and 20 km (MJAR, ESDC, ILAR, KSRS, CMAR, ASAR, and EKA) can provide robust parameter estimates subject to a smoothing of the resulting slowness grids, most effectively achieved by convolving the measured slowness grids with the array response function for a 4 or 5 second period signal. The MJAR array in Japan recorded high SNR Pn signals for both the 2006 and 2009 North Korea

Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

NASA Technical Reports Server (NTRS)

Kerwin, W. J.; Shaffer, C. V.

1968-01-01

Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

On-Orbit Reconfigurable Solar Array

NASA Technical Reports Server (NTRS)

Levy, Robert K. (Inventor)

2017-01-01

In one or more embodiments, the present disclosure teaches a method for reconfiguring a solar array. The method involves providing, for the solar array, at least one string of solar cells. The method further involves deactivating at least a portion of at least one of the strings of solar cells of the solar array when power produced by the solar array reaches a maximum power allowance threshold. In addition, the method involves activating at least a portion of at least one of the strings of the solar cells in the solar array when the power produced by the solar array reaches a minimum power allowance threshold.

Linkage maps of grapevine displaying the chromosomal locations of 420 microsatellite markers and 82 markers for R-gene candidates.

PubMed

Di Gaspero, G; Cipriani, G; Adam-Blondon, A-F; Testolin, R

2007-05-01

Genetic maps functionally oriented towards disease resistance have been constructed in grapevine by analysing with a simultaneous maximum-likelihood estimation of linkage 502 markers including microsatellites and resistance gene analogs (RGAs). Mapping material consisted of two pseudo-testcrosses, 'Chardonnay' x 'Bianca' and 'Cabernet Sauvignon' x '20/3' where the seed parents were Vitis vinifera genotypes and the male parents were Vitis hybrids carrying resistance to mildew diseases. Individual maps included 320-364 markers each. The simultaneous use of two mapping crosses made with two pairs of distantly related parents allowed mapping as much as 91% of the markers tested. The integrated map included 420 Simple Sequence Repeat (SSR) markers that identified 536 SSR loci and 82 RGA markers that identified 173 RGA loci. This map consisted of 19 linkage groups (LGs) corresponding to the grape haploid chromosome number, had a total length of 1,676 cM and a mean distance between adjacent loci of 3.6 cM. Single-locus SSR markers were randomly distributed over the map (CD = 1.12). RGA markers were found in 18 of the 19 LGs but most of them (83%) were clustered on seven LGs, namely groups 3, 7, 9, 12, 13, 18 and 19. Several RGA clusters mapped to chromosomal regions where phenotypic traits of resistance to fungal diseases such as downy mildew and powdery mildew, bacterial diseases such as Pierce's disease, and pests such as dagger and root-knot nematode, were previously mapped in different segregating populations. The high number of RGA markers integrated into this new map will help find markers linked to genetic determinants of different pest and disease resistances in grape.

Improved Gain Microstrip Patch Antenna

DTIC Science & Technology

2015-08-06

08-2015 Publication Improved Gain Microstrip Patch Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L...GAIN MICROSTRIP PATCH ANTENNA STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and used by or for the...patch antenna having increased gain, and an apparatus for increasing the gain and bandwidth of an existing microstrip patch antenna . (2) Description

Integrated Avalanche Photodiode arrays

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

Harmon, Eric S.

2017-04-18

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

Integrated avalanche photodiode arrays

DOEpatents

Harmon, Eric S.

2015-07-07

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

Toward Scintillator High-Gain Avalanche Rushing Photoconductor Active Matrix Flat Panel Imager (SHARP-AMFPI): Initial fabrication and characterization.

PubMed

Scheuermann, James R; Howansky, Adrian; Hansroul, Marc; Léveillé, Sébastien; Tanioka, Kenkichi; Zhao, Wei

2018-02-01

We present the first prototype Scintillator High-Gain Avalanche Rushing Photoconductor Active Matrix Flat Panel Imager (SHARP-AMFPI). This detector includes a layer of avalanche amorphous Selenium (a-Se) (HARP) as the photoconductor in an indirect detector to amplify the signal and reduce the effects of electronic noise to obtain quantum noise-limited images for low-dose applications. It is the first time avalanche a-Se has been used in a solid-state imaging device and poses as a possible solution to eliminate the effects of electronic noise, which is crucial for low-dose imaging performance of AMFPI. We successfully deposited a solid-state HARP structure onto a 24 × 30 cm 2 array of thin-film transistors (TFT array) with a pixel pitch of 85 μm. The HARP layer consists of 16 μm of a-Se with a hole-blocking and electron-blocking layer to prevent charge injection from the high-voltage bias and pixel electrodes, respectively. An electric field (E S e ) up to 105 V μm -1 was applied across the a-Se layer without breakdown. A 150 μm thick-structured CsI:Tl scintillator was used to form SHARP-AMFPI. The x-ray imaging performance is characterized using a 30 kVp Mo/Mo beam. We evaluate the spatial resolution, noise power, and detective quantum efficiency at zero frequency of the system with and without avalanche gain. The results are analyzed using cascaded linear system model (CLSM). An avalanche gain of 76 ± 5 was measured at E S e = 105 V μm -1 . We demonstrate that avalanche gain can amplify the signal to overcome electronic noise. As avalanche gain is increased, image quality improves for a constant (0.76 mR) exposure until electronic noise is overcome. Our system is currently limited by poor optical transparency of our high-voltage electrode and long integrating time which results in dark current noise. These two effects cause high-spatial frequency noise to dominate imaging performance. We demonstrate the feasibility of a solid-state HARP x-ray imager and

EzArray: A web-based highly automated Affymetrix expression array data management and analysis system

PubMed Central

Zhu, Yuerong; Zhu, Yuelin; Xu, Wei

2008-01-01

Background Though microarray experiments are very popular in life science research, managing and analyzing microarray data are still challenging tasks for many biologists. Most microarray programs require users to have sophisticated knowledge of mathematics, statistics and computer skills for usage. With accumulating microarray data deposited in public databases, easy-to-use programs to re-analyze previously published microarray data are in high demand. Results EzArray is a web-based Affymetrix expression array data management and analysis system for researchers who need to organize microarray data efficiently and get data analyzed instantly. EzArray organizes microarray data into projects that can be analyzed online with predefined or custom procedures. EzArray performs data preprocessing and detection of differentially expressed genes with statistical methods. All analysis procedures are optimized and highly automated so that even novice users with limited pre-knowledge of microarray data analysis can complete initial analysis quickly. Since all input files, analysis parameters, and executed scripts can be downloaded, EzArray provides maximum reproducibility for each analysis. In addition, EzArray integrates with Gene Expression Omnibus (GEO) and allows instantaneous re-analysis of published array data. Conclusion EzArray is a novel Affymetrix expression array data analysis and sharing system. EzArray provides easy-to-use tools for re-analyzing published microarray data and will help both novice and experienced users perform initial analysis of their microarray data from the location of data storage. We believe EzArray will be a useful system for facilities with microarray services and laboratories with multiple members involved in microarray data analysis. EzArray is freely available from . PMID:18218103

Microfabricated ion trap array

DOEpatents

Blain, Matthew G [Albuquerque, NM; Fleming, James G [Albuquerque, NM

2006-12-26

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

Design and Test of Magnetic Wall Decoupling for Dipole Transmit/Receive Array for MR Imaging at the Ultrahigh Field of 7T.

PubMed

Yan, Xinqiang; Zhang, Xiaoliang; Wei, Long; Xue, Rong

2015-01-01

Radio-frequency coil arrays using dipole antenna technique have been recently applied for ultrahigh field magnetic resonance (MR) imaging to obtain the better signal-noise-ratio (SNR) gain at the deep area of human tissues. However, the unique structure of dipole antennas makes it challenging to achieve sufficient electromagnetic decoupling among the dipole antenna elements. Currently, there is no decoupling methods proposed for dipole antenna arrays in MR imaging. The recently developed magnetic wall (MW) or induced current elimination decoupling technique has demonstrated its feasibility and robustness in designing microstrip transmission line arrays, L/C loop arrays and monopole arrays. In this study, we aim to investigate the possibility and performance of MW decoupling technique in dipole arrays for MR imaging at the ultrahigh field of 7T. To achieve this goal, a two-channel MW decoupled dipole array was designed, constructed and analyzed experimentally through bench test and MR imaging. Electromagnetic isolation between the two dipole elements was improved from about -3.6 dB (without any decoupling treatments) to -16.5 dB by using the MW decoupling method. MR images acquired from a water phantom using the MW decoupled dipole array and the geometry factor maps were measured, calculated and compared with those acquired using the dipole array without decoupling treatments. The MW decoupled dipole array demonstrated well-defined image profiles from each element and had better geometry factor over the array without decoupling treatments. The experimental results indicate that the MW decoupling technique might be a promising solution to reducing the electromagnetic coupling of dipole arrays in ultrahigh field MRI, consequently improving their performance in SNR and parallel imaging.

A Pneumococcal Protein Array as a Platform to Discover Serodiagnostic Antigens Against Infection*

PubMed Central

Olaya-Abril, Alfonso; Jiménez-Munguía, Irene; Gómez-Gascón, Lidia; Obando, Ignacio; Rodríguez-Ortega, Manuel J.

2015-01-01

Pneumonia is one of the most common and severe diseases associated with Streptococcus pneumoniae infections in children and adults. Etiological diagnosis of pneumococcal pneumonia in children is generally challenging because of limitations of diagnostic tests and interference with nasopharyngeal colonizing strains. Serological assays have recently gained interest to overcome some problems found with current diagnostic tests in pediatric pneumococcal pneumonia. To provide insight into this field, we have developed a protein array to screen the antibody response to many antigens simultaneously. Proteins were selected by experimental identification from a collection of 24 highly prevalent pediatric clinical isolates in Spain, using a proteomics approach consisting of “shaving” the cell surface with proteases and further LC/MS/MS analysis. Ninety-five proteins were recombinantly produced and printed on an array. We probed it with a collection of sera from children with pneumococcal pneumonia. From the set of the most seroprevalent antigens, we obtained a clear discriminant response for a group of three proteins (PblB, PulA, and PrtA) in children under 4 years old. We validated the results by ELISA and an immunostrip assay showed the translation to easy-to-use, affordable tests. Thus, the protein array here developed presents a tool for broad use in serodiagnostics. PMID:26183717

Simultaneous Profiling of DNA Mutation and Methylation by Melting Analysis Using Magnetoresistive Biosensor Array.

PubMed

Rizzi, Giovanni; Lee, Jung-Rok; Dahl, Christina; Guldberg, Per; Dufva, Martin; Wang, Shan X; Hansen, Mikkel F

2017-09-26

Epigenetic modifications, in particular DNA methylation, are gaining increasing interest as complementary information to DNA mutations for cancer diagnostics and prognostics. We introduce a method to simultaneously profile DNA mutation and methylation events for an array of sites with single site specificity. Genomic (mutation) or bisulphite-treated (methylation) DNA is amplified using nondiscriminatory primers, and the amplicons are then hybridized to a giant magnetoresistive (GMR) biosensor array followed by melting curve measurements. The GMR biosensor platform offers scalable multiplexed detection of DNA hybridization, which is insensitive to temperature variation. The melting curve approach further enhances the assay specificity and tolerance to variations in probe length. We demonstrate the utility of this method by simultaneously profiling five mutation and four methylation sites in human melanoma cell lines. The method correctly identified all mutation and methylation events and further provided quantitative assessment of methylation density validated by bisulphite pyrosequencing.

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis

PubMed Central

Scaria, Joy; Sreedharan, Aswathy; Chang, Yung-Fu

2008-01-01

Background Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays. Methods Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET. Conclusion MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays. PMID:18811969

Microbial Diagnostic Array Workstation (MDAW): a web server for diagnostic array data storage, sharing and analysis.

PubMed

Scaria, Joy; Sreedharan, Aswathy; Chang, Yung-Fu

2008-09-23

Microarrays are becoming a very popular tool for microbial detection and diagnostics. Although these diagnostic arrays are much simpler when compared to the traditional transcriptome arrays, due to the high throughput nature of the arrays, the data analysis requirements still form a bottle neck for the widespread use of these diagnostic arrays. Hence we developed a new online data sharing and analysis environment customised for diagnostic arrays. Microbial Diagnostic Array Workstation (MDAW) is a database driven application designed in MS Access and front end designed in ASP.NET. MDAW is a new resource that is customised for the data analysis requirements for microbial diagnostic arrays.

Filter arrays

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

Page, Ralph H.; Doty, Patrick F.

2017-08-01

The various technologies presented herein relate to a tiled filter array that can be used in connection with performance of spatial sampling of optical signals. The filter array comprises filter tiles, wherein a first plurality of filter tiles are formed from a first material, the first material being configured such that only photons having wavelengths in a first wavelength band pass therethrough. A second plurality of filter tiles is formed from a second material, the second material being configured such that only photons having wavelengths in a second wavelength band pass therethrough. The first plurality of filter tiles and themore » second plurality of filter tiles can be interspersed to form the filter array comprising an alternating arrangement of first filter tiles and second filter tiles.« less

A Radio-Frequency-over-Fiber link for large-array radio astronomy applications

NASA Astrophysics Data System (ADS)

Mena, J.; Bandura, K.; Cliche, J.-F.; Dobbs, M.; Gilbert, A.; Tang, Q. Y.

2013-10-01

A prototype 425-850 MHz Radio-Frequency-over-Fiber (RFoF) link for the Canadian Hydrogen Intensity Mapping Experiment (CHIME) is presented. The design is based on a directly modulated Fabry-Perot (FP) laser, operating at ambient temperature, and a single-mode fiber. The dynamic performance, gain stability, and phase stability of the RFoF link are characterized. Tests on a two-element interferometer built at the Dominion Radio Astrophysical Observatory for CHIME prototyping demonstrate that RFoF can be successfully used as a cost-effective solution for analog signal transport on the CHIME telescope and other large-array radio astronomy applications.

Multi-anode microchannel arrays

NASA Technical Reports Server (NTRS)

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

1977-01-01

A development program is currently being undertaken to produce photon-counting detector arrays which are suitable for use in both ground-based and space-borne instruments and which utilize the full sensitivity, dynamic range and photometric stability of the microchannel array plate (MCP). The construction of the detector arrays and the status of the development program are described.

Clocked combustor can array

DOEpatents

Kim, Won-Wook; McMahan, Kevin Weston; Srinivasan, Shiva Kumar

2017-01-17

The present application provides a clocked combustor can array for coherence reduction in a gas turbine engine. The clocked combustor can array may include a number of combustor cans positioned in a circumferential array. A first set of the combustor cans may have a first orientation and a second set of the combustor cans may have a second orientation.

The NMR phased array.

PubMed

Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

1990-11-01

We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm).

Electrically reconfigurable logic array

NASA Technical Reports Server (NTRS)

Agarwal, R. K.

1982-01-01

To compose the complicated systems using algorithmically specialized logic circuits or processors, one solution is to perform relational computations such as union, division and intersection directly on hardware. These relations can be pipelined efficiently on a network of processors having an array configuration. These processors can be designed and implemented with a few simple cells. In order to determine the state-of-the-art in Electrically Reconfigurable Logic Array (ERLA), a survey of the available programmable logic array (PLA) and the logic circuit elements used in such arrays was conducted. Based on this survey some recommendations are made for ERLA devices.

Solid state neutron detector array

DOEpatents

Seidel, J.G.; Ruddy, F.H.; Brandt, C.D.; Dulloo, A.R.; Lott, R.G.; Sirianni, E.; Wilson, R.O.

1999-08-17

A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors. 7 figs.

Solid state neutron detector array

DOEpatents

Seidel, John G.; Ruddy, Frank H.; Brandt, Charles D.; Dulloo, Abdul R.; Lott, Randy G.; Sirianni, Ernest; Wilson, Randall O.

1999-01-01

A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors.

Multibeam Phased Array Antennas

NASA Technical Reports Server (NTRS)

Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

2004-01-01

In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

High density pixel array

NASA Technical Reports Server (NTRS)

McFall, James Earl (Inventor); Wiener-Avnear, Eliezer (Inventor)

2004-01-01

A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

Association of gestational weight gain expectations with advice on actual weight gain

USDA-ARS?s Scientific Manuscript database

To examine pregnant women's gestational weight gain expectations/advice from various sources (i.e., self, family/friends, physician) and the impact of these sources of expectations/advice on actual measured gestational weight gain. Pregnant women (n=230, 87.4% Caucasian, second pregnancy) in a cohor...

Weight Gain during Pregnancy

MedlinePlus

... Global Map Premature Birth Report Cards Careers Archives Pregnancy Before or between pregnancies Nutrition, weight & fitness Prenatal ... fitness > Weight gain during pregnancy Weight gain during pregnancy E-mail to a friend Please fill in ...

Asthma Triggers: Gain Control

MedlinePlus

... Centers Asthma Contact Us Share Asthma Triggers: Gain Control Breathing Freely: Controlling Asthma Triggers This video features ... Air Quality: Biological Pollutants Help Your Child Gain Control Over Asthma Top of Page Molds About Molds ...

Planar waveguide integrated spatial filter array

NASA Astrophysics Data System (ADS)

Ai, Jun; Dimov, Fedor; Lyon, Richard; Rakuljic, Neven; Griffo, Chris; Xia, Xiaowei; Arik, Engin

2013-09-01

An innovative integrated spatial filter array (iSFA) was developed for the nulling interferometer for the detection of earth-like planets and life beyond our solar system. The coherent iSFA comprised a 2D planar lightwave circuit (PLC) array coupled with a pair of 2D lenslet arrays in a hexagonal grid to achieve the optimum fill factor and throughput. The silica-on-silicon waveguide mode field diameter and numerical aperture (NA) were designed to match with the Airy disc and NA of the microlens for optimum coupling. The lenslet array was coated with a chromium pinhole array at the focal plane to pass the single-mode waveguide but attenuate the higher modes. We assembled a 32 by 30 array by stacking 32 chips that were produced by photolithography from a 6-in. silicon wafer. Each chip has 30 planar waveguides. The PLC array is inherently polarization-maintaining (PM) and requires much less alignment in contrast to a fiber array, where each PM fiber must be placed individually and oriented correctly. The PLC array offers better scalability than the fiber bundle array for large arrays of over 1,000 waveguides.

DELLA proteins negatively regulate dark-induced senescence and chlorophyll degradation in Arabidopsis through interaction with the transcription factor WRKY6.

PubMed

Zhang, Yongqiang; Liu, Zhongjuan; Wang, Xiaoyun; Wang, Jianfeng; Fan, Kai; Li, Zhaowei; Lin, Wenxiong

2018-03-24

DELLA proteins' negative regulation of dark-induced senescence and chlorophyll degradation in Arabidopsis is through interaction with WRKY6 and thus repression of its transcriptional activities on senescence-related genes. Senescence is an intricate and highly orchestrated process regulated by numerous endogenous and environmental signals. Gibberellins (GAs) and their signaling components DELLA proteins have been known to participate in the regulation of senescence. However, the mechanism of the GA-DELLA system involved in the senescence process remains largely unclear. Darkness is a known environmental factor that induces plant senescence. In this study, exogenous GA 3 (an active form of GA) accelerated but paclobutrazol (a specific GA biosynthesis inhibitor) retarded dark-induced leaf yellowing in Arabidopsis. Moreover, the dark-triggered decrease in chlorophyll content, increase in cell membrane leakage, and upregulation of senescence-associated genes were notably impaired in both endogenous GA-decreased mutants ga3ox1/ga3ox2 and ga20ox1/ga20ox2 compared with those in wild-type Col-0. These effects of darkness were enhanced in the quintuple mutant of DELLA genes gai-t6/rga-t2/rgl1-1/rgl2-1/rgl3-1 and conversely attenuated in the gain-of-function mutant gai and transgenic plant 35S::TAP-RGAd17 compared with wild-type Ler. Subsequently, RGA interacted with the transcription factor WRKY6 in a yeast two-hybrid assay, as confirmed by bimolecular fluorescence complementation and pull-down analyses. In addition, mutation and overexpression of WRKY6 retarded and accelerated dark-induced senescence, respectively. Furthermore, transient expression assays in Arabidopsis protoplasts indicated that RGA and GAI weakened the transcriptional activities of WRKY6 on its downstream senescence-related genes, including SAG13 and SGR. Taken together, these results suggest that GAs positively and DELLAs negatively regulate dark-induced senescence and chlorophyll degradation in

Engineering study of the module/array interface for large terrestrial photovoltaic arrays

NASA Technical Reports Server (NTRS)

1977-01-01

Three major areas--structural, electrical, and maintenance--were evaluated. Efforts in the structural area included establishing acceptance criteria for materials and members, determining loading criteria, and analyzing glass modules in various framing system configurations. Array support structure design was addressed briefly. Electrical considerations included evaluation of module characteristics, intermodule connectors, array wiring, converters and lightning protection. Plant maintenance features such as array cleaning, failure detection, and module installation and replacement were addressed.

The Advanced ACTPol 27/39 GHz Array

NASA Astrophysics Data System (ADS)

Simon, S. M.; Beall, J. A.; Cothard, N. F.; Duff, S. M.; Gallardo, P. A.; Ho, S. P.; Hubmayr, J.; Koopman, B. J.; McMahon, J. J.; Nati, F.; Niemack, M. D.; Staggs, S. T.; Vavagiakis, E. M.; Wollack, E. J.

2018-05-01

Advanced ACTPol (AdvACT) will observe the temperature and polarization of the cosmic microwave background (CMB) at multiple frequencies and high resolution to place improved constraints on inflation, dark matter, and dark energy. Foregrounds from synchrotron and dust radiation are a source of contamination that must be characterized and removed across a wide range of frequencies. AdvACT will thus observe at five frequency bands from 27 to 230 GHz. We discuss the design of the pixels and feedhorns for the 27/39 GHz multichroic array for AdvACT, which will target the synchrotron radiation that dominates at these frequencies. To gain 35% in mapping speed in the 39 GHz band where the foreground signals are faintest, the pixel number was increased through reducing the pixel diameter to 1.08λ at the lowest frequency, which represents a 22% decrease in size compared to our previously most tightly packed pixels.

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)

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

Zhao Wei; Li Dan; Reznik, Alla

2005-09-15

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoidmore » pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d{sub Se} and the applied electric field E{sub Se} of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E{sub Se} dependence of both avalanche gain and optical quantum efficiency of an 8 {mu}m HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E{sub Se}: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 {mu}m can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.« less

College Freshmen Students’ Perspectives on Weight Gain Prevention in the Digital Age: Web-Based Survey

PubMed Central

Turner-McGrievy, Gabrielle; Larsen, Chelsea A; Magradey, Karen; Brandt, Heather M; Wilcox, Sara; Sundstrom, Beth; West, Delia Smith

2017-01-01

management to 70% [35/50] for eating a healthy diet and staying physically active). Email was the most frequently used electronic platform, with 96% (48/50) of students reporting current use of it. Email was also the most frequently cited preferred eHealth delivery platform, with 86% (43/50) of students selecting it. Facebook was preferred by the second greatest proportion of students (40%, 20/50). Conclusions Most college freshmen have concerns about an array of weight gain prevention topics and are generally open to the possibility of receiving eHealth interventions designed to address their concerns, preferably via email compared with popular social media platforms. These preliminary findings offer a foundation to build upon when it comes to future descriptive investigations focused on behavioral weight gain prevention among college freshmen in the digital age. PMID:29025698

A coherent through-wall MIMO phased array imaging radar based on time-duplexed switching

NASA Astrophysics Data System (ADS)

Chen, Qingchao; Chetty, Kevin; Brennan, Paul; Lok, Lai Bun; Ritchie, Matthiew; Woodbridge, Karl

2017-05-01

Through-the-Wall (TW) radar sensors are gaining increasing interest for security, surveillance and search and rescue applications. Additionally, the integration of Multiple-Input, Multiple-Output (MIMO) techniques with phased array radar is allowing higher performance at lower cost. In this paper we present a 4-by-4 TW MIMO phased array imaging radar operating at 2.4 GHz with 200 MHz bandwidth. To achieve high imaging resolution in a cost-effective manner, the 4 Tx and 4 Rx elements are used to synthesize a uniform linear array (ULA) of 16 virtual elements. Furthermore, the transmitter is based on a single-channel 4-element time-multiplexed switched array. In transmission, the radar utilizes frequency modulated continuous wave (FMCW) waveforms that undergo de-ramping on receive to allow digitization at relatively low sampling rates, which then simplifies the imaging process. This architecture has been designed for the short-range TW scenarios envisaged, and permits sufficient time to switch between antenna elements. The paper first outlines the system characteristics before describing the key signal processing and imaging algorithms which are based on traditional Fast Fourier Transform (FFT) processing. These techniques are implemented in LabVIEW software. Finally, we report results from an experimental campaign that investigated the imaging capabilities of the system and demonstrated the detection of personnel targets. Moreover, we show that multiple targets within a room with greater than approximately 1 meter separation can be distinguished from one another.

Water quality in Gaines Creek and Gaines Creek arm of Eufaula Lake, Oklahoma

USGS Publications Warehouse

Kurklin, J.K.

1990-01-01

Based on samples collected from May 1978 to May 1980 and analyzed for major anions, nitrogen, trace elements, phytoplankton, and bacteria, the water in Gaines Creek and the Gaines Creek arm of Eufaula Lake was similar with respect to suitability for municipal use. Water from Gaines Creek had a pH range of 5.7 to 7.6 and a maximum specific conductance of 97 microsiemens per centimeter at 25o Celsius, whereas water from the Gaines Creek arm of Eufaula Lake had a pH range of 6.0 to 9.2 and a maximum specific conductance of 260 microsiemens per centimeter at 25o Celsius. Dissolved oxygen, pH, temperature, and specific conductance values for the lake varied with depth. With the exceptions of cadmium, iron, lead, and manganese, trace-element determinations of samples were within recommended national primary and secondary drinking-water standards. When compared to the National Academy of Sciences water-quality criteria, phytoplankton and bacteria counts exceeded recommendations; however, water from either Gaines Creek or Eufaula Lake could be treated similarly and used as a municipal water supply.

Developing an Inflatable Solar Array

NASA Technical Reports Server (NTRS)

Malone, Patrick K.; Jankowski, Francis J.; Williams, Geoffery T.; Vendura, George J., Jr.

1992-01-01

Viewgraphs describing the development of an inflatable solar array as part of the Inflatable Torus Solar Array Technology (ITSAT) program are presented. Program phases, overall and subsystem designs, and array deployment are addressed.

Piezo-generator integrating a vertical array of GaN nanowires.

PubMed

Jamond, N; Chrétien, P; Houzé, F; Lu, L; Largeau, L; Maugain, O; Travers, L; Harmand, J C; Glas, F; Lefeuvre, E; Tchernycheva, M; Gogneau, N

2016-08-12

We demonstrate the first piezo-generator integrating a vertical array of GaN nanowires (NWs). We perform a systematic multi-scale analysis, going from single wire properties to macroscopic device fabrication and characterization, which allows us to establish for GaN NWs the relationship between the material properties and the piezo-generation, and to propose an efficient piezo-generator design. The piezo-conversion of individual MBE-grown p-doped GaN NWs in a dense array is assessed by atomic force microscopy (AFM) equipped with a Resiscope module yielding an average output voltage of 228 ± 120 mV and a maximum value of 350 mV generated per NW. In the case of p-doped GaN NWs, the piezo-generation is achieved when a positive piezo-potential is created inside the nanostructures, i.e. when the NWs are submitted to compressive deformation. The understanding of the piezo-generation mechanism in our GaN NWs, gained from AFM analyses, is applied to design a piezo-generator operated under compressive strain. The device consists of NW arrays of several square millimeters in size embedded into spin-on glass with a Schottky contact for rectification and collection of piezo-generated carriers. The generator delivers a maximum power density of ∼12.7 mW cm(-3). This value sets the new state of the art for piezo-generators based on GaN NWs and more generally on nitride NWs, and offers promising prospects for the use of GaN NWs as high-efficiency ultra-compact energy harvesters.

Microelectronic electroporation array

NASA Astrophysics Data System (ADS)

Johnson, Lee J.; Shaffer, Kara J.; Skeath, Perry; Perkins, Frank K.; Pancrazio, Joseph; Scribner, Dean

2004-06-01

Gene Array technology has allowed for the study of gene binding by creating thousands of potential binding sites on a single device. A limitation of the current technology is that the effects of the gene and the gene-derived proteins cannot be studied in situ the same way, thousand site cell arrays are not readily available. We propose a new device structure to study the effects of gene modification on cells. This new array technology uses electroporation to target specific areas within a cell culture for transfection of genes. Electroporation arrays will allow high throughput analysis of gene effects on a given cell's response to a stress or a genes ability to restore normal cell function in disease modeling cells. Fluorescent imaging of dye labeled indicator molecules or cell viability will provide results indicating the most effective genes. The electroporation array consists of a microelectronic circuit, ancillary electronics, protecting electrode surface for cell culturing and a perfusion system for gene or drug delivery. The advantages of the current device are that there are 3200 sites for electroporation, all or any subsets of the electrodes can be activated. The cells are held in place by the electrode material. This technology could also be applied to high throughput screening of cell impermeant drugs.

A Wide-Band High-Gain Compact SIS Receiver Utilizing a 300-μW SiGe IF LNA

NASA Astrophysics Data System (ADS)

Montazeri, Shirin; Grimes, Paul K.; Tong, Cheuk-Yu Edward; Bardin, Joseph C.

2017-06-01

Low-power low-noise amplifiers integrated with superconductor-insulator-superconductor (SIS) mixers are required to enable implementation of large-scale focal plane arrays. In this work, a 220-GHz SIS mixer has been integrated with a high-gain broad-band low-power IF amplifier into a compact receiver module. The low noise amplifier (LNA) was specifically designed to match to the SIS output impedance and contributes less than 7 K to the system noise temperature over the 4-8 GHz IF frequency range. A receiver noise temperature of 30-45 K was measured for a local oscillator frequency of 220 GHz over an IF spanning 4-8 GHz. The LNA power dissipation was only 300-μW. To the best of the authors' knowledge, this is the lowest power consumption reported for a high-gain wide-band LNA directly integrated with an SIS mixer.

Electrode array for neural stimulation

DOEpatents

Wessendorf, Kurt O [Albuquerque, NM; Okandan, Murat [Edgewood, NM; Stein, David J [Albuquerque, NM; Yang, Pin [Albuquerque, NM; Cesarano, III, Joseph; Dellinger, Jennifer [Albuquerque, NM

2011-08-16

An electrode array for neural stimulation is disclosed which has particular applications for use in a retinal prosthesis. The electrode array can be formed as a hermetically-sealed two-part ceramic package which includes an electronic circuit such as a demultiplexer circuit encapsulated therein. A relatively large number (up to 1000 or more) of individually-addressable electrodes are provided on a curved surface of a ceramic base portion the electrode array, while a much smaller number of electrical connections are provided on a ceramic lid of the electrode array. The base and lid can be attached using a metal-to-metal seal formed by laser brazing. Electrical connections to the electrode array can be provided by a flexible ribbon cable which can also be used to secure the electrode array in place.

Downsampling Photodetector Array with Windowing

NASA Technical Reports Server (NTRS)

Patawaran, Ferze D.; Farr, William H.; Nguyen, Danh H.; Quirk, Kevin J.; Sahasrabudhe, Adit

2012-01-01

In a photon counting detector array, each pixel in the array produces an electrical pulse when an incident photon on that pixel is detected. Detection and demodulation of an optical communication signal that modulated the intensity of the optical signal requires counting the number of photon arrivals over a given interval. As the size of photon counting photodetector arrays increases, parallel processing of all the pixels exceeds the resources available in current application-specific integrated circuit (ASIC) and gate array (GA) technology; the desire for a high fill factor in avalanche photodiode (APD) detector arrays also precludes this. Through the use of downsampling and windowing portions of the detector array, the processing is distributed between the ASIC and GA. This allows demodulation of the optical communication signal incident on a large photon counting detector array, as well as providing architecture amenable to algorithmic changes. The detector array readout ASIC functions as a parallel-to-serial converter, serializing the photodetector array output for subsequent processing. Additional downsampling functionality for each pixel is added to this ASIC. Due to the large number of pixels in the array, the readout time of the entire photodetector is greater than the time between photon arrivals; therefore, a downsampling pre-processing step is done in order to increase the time allowed for the readout to occur. Each pixel drives a small counter that is incremented at every detected photon arrival or, equivalently, the charge in a storage capacitor is incremented. At the end of a user-configurable counting period (calculated independently from the ASIC), the counters are sampled and cleared. This downsampled photon count information is then sent one counter word at a time to the GA. For a large array, processing even the downsampled pixel counts exceeds the capabilities of the GA. Windowing of the array, whereby several subsets of pixels are designated

Rectenna array measurement results

NASA Technical Reports Server (NTRS)

Dickinson, R. M.

1980-01-01

The measured performance characteristics of a rectenna array are reviewed and compared to the performance of a single element. It is shown that the performance may be extrapolated from the individual element to that of the collection of elements. Techniques for current and voltage combining were demonstrated. The array performance as a function of various operating parameters is characterized and techniques for overvoltage protection and automatic fault clearing in the array demonstrated. A method for detecting failed elements also exists. Instrumentation for deriving performance effectiveness is described. Measured harmonic radiation patterns and fundamental frequency scattered patterns for a low level illumination rectenna array are presented.

Arrayed waveguide Sagnac interferometer.

PubMed

Capmany, José; Muñoz, Pascual; Sales, Salvador; Pastor, Daniel; Ortega, Beatriz; Martinez, Alfonso

2003-02-01

We present a novel device, an arrayed waveguide Sagnac interferometer, that combines the flexibility of arrayed waveguides and the wide application range of fiber or integrated optics Sagnac loops. We form the device by closing an array of wavelength-selective light paths provided by two arrayed waveguides with a single 2 x 2 coupler in a Sagnac configuration. The equations that describe the device's operation in general conditions are derived. A preliminary experimental demonstration is provided of a fiber prototype in passive operation that shows good agreement with the expected theoretical performance. Potential applications of the device in nonlinear operation are outlined and discussed.

High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

NASA Astrophysics Data System (ADS)

Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

2013-05-01

We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to <= 400 kcps per channel. We selected Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) and a brand-new scintillator, Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) due to their high light yield and density. To improve the spatial resolution, these scintillators were fabricated into 15 × 15 matrices of 0.5 × 0.5 mm2 pixels. The Ce:LYSO and Ce:GAGG scintillator matrices were assembled into phosphor sandwich (phoswich) detectors, and then coupled to the MPPC array along with an acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

Multi-Layer Tiled Array.

DTIC Science & Technology

1996-12-16

the Invention 13 The present invention relates to planar sonar arrays. More 14 particularly, the invention relates to the arrangement of 15...transducer elements in planar sonar arrays. 16 (2) Description of the Prior Art 17 Conventional planar sonar array designs typically comprise 18 ceramic...signal 5 conditioners ( preamplifiers )/as short as possible. However, this 6 requirement complicates fabrication and provides little space to 7

Microbe observation and cultivation array (MOCA) for cultivating and analyzing environmental microbiota.

PubMed

Gao, Weimin; Navarroli, Dena; Naimark, Jared; Zhang, Weiwen; Chao, Shih-Hui; Meldrum, Deirdre R

2013-01-09

The use of culture-independent nucleic acid techniques, such as ribosomal RNA gene cloning library analysis, has unveiled the tremendous microbial diversity that exists in natural environments. In sharp contrast to this great achievement is the current difficulty in cultivating the majority of bacterial species or phylotypes revealed by molecular approaches. Although recent new technologies such as metagenomics and metatranscriptomics can provide more functionality information about the microbial communities, it is still important to develop the capacity to isolate and cultivate individual microbial species or strains in order to gain a better understanding of microbial physiology and to apply isolates for various biotechnological applications. We have developed a new system to cultivate bacteria in an array of droplets. The key component of the system is the microbe observation and cultivation array (MOCA), which consists of a Petri dish that contains an array of droplets as cultivation chambers. MOCA exploits the dominance of surface tension in small amounts of liquid to spontaneously trap cells in well-defined droplets on hydrophilic patterns. During cultivation, the growth of the bacterial cells across the droplet array can be monitored using an automated microscope, which can produce a real-time record of the growth. When bacterial cells grow to a visible microcolony level in the system, they can be transferred using a micropipette for further cultivation or analysis. MOCA is a flexible system that is easy to set up, and provides the sensitivity to monitor growth of single bacterial cells. It is a cost-efficient technical platform for bioassay screening and for cultivation and isolation of bacteria from natural environments.

Phased Array Theory and Technology

DTIC Science & Technology

1981-07-01

Generalized Array Coordinates 2. Linear, Planar and Circular Art -ays 3. Periodic fwo Dimensional ^rras 4. Grating Lobe Lattices 5. 1’llenienl...formal and low profile antennas, antennas for limited sector coverage, and wide- band array feeds. To aid designers, there is an attempt to give ...ol Vol. 2, Elliott gives convenient formulas lor the directivity of Imear dipole arrays, and derives an especially simple form tor arrays

Remote intracranial recurrence of IDH mutant gliomas is associated with TP53 mutations and an 8q gain

PubMed Central

Nakae, Shunsuke; Kato, Takema; Murayama, Kazuhiro; Sasaki, Hikaru; Abe, Masato; Kumon, Masanobu; Kumai, Tadashi; Yamashiro, Kei; Inamasu, Joji; Hasegawa, Mitsuhiro; Kurahashi, Hiroki; Hirose, Yuichi

2017-01-01

Most IDH mutant gliomas harbor either 1p/19q co-deletions or TP53 mutation; 1p/19q co-deleted tumors have significantly better prognoses than tumors harboring TP53 mutations. To investigate the clinical factors that contribute to differences in tumor progression of IDH mutant gliomas, we classified recurrent tumor patterns based on MRI and correlated these patterns with their genomic characterization. Accordingly, in IDH mutant gliomas (N = 66), 1p/19 co-deleted gliomas only recurred locally, whereas TP53 mutant gliomas recurred both locally and in remote intracranial regions. In addition, diffuse tensor imaging suggested that remote intracranial recurrence in the astrocytomas, IDH-mutant with TP53 mutations may occur along major fiber bundles. Remotely recurrent tumors resulted in a higher mortality and significantly harbored an 8q gain; astrocytomas with an 8q gain resulted in significantly shorter overall survival than those without an 8q gain. OncoScan® arrays and next-generation sequencing revealed specific 8q regions (i.e., between 8q22 and 8q24) show a high copy number. In conclusion, only tumors with TP53 mutations showed patterns of remote recurrence in IDH mutant gliomas. Furthermore, an 8q gain was significantly associated with remote intracranial recurrence and can be considered a poor prognostic factor in astrocytomas, IDH-mutant. PMID:29156679

Broadband acoustic phased array with subwavelength active tube array

NASA Astrophysics Data System (ADS)

Li, Xiao-Yan; Yang, Zhang-Zhao; Zhu, Yi-Fan; Zou, Xin-Ye; Cheng, Jian-Chun

2018-02-01

Acoustic metasurfaces provide a way to manipulate wavefronts at anomalous reflection or refraction angles through subwavelength structures. Here, based on the generalized Snell's refraction law for acoustic metasurfaces and the classical acoustic phased array (PA) theory, a broadband acoustic PA with a subwavelength active tube array has been proposed to form a special acoustic beam and to determine the directivity characteristics of the acoustic source. Theoretical analysis shows that the dispersionless wavefront manipulation can be realized by the gradient model of the active tube array, and a wide working frequency band can be obtained in practical applications from the simulated and experimental results. The numerical results of forming a special acoustic beam and establishing an acoustic focus model with an arbitrary focal position are consistent with the theoretical predictions. The experimental results agree well with the simulated results in the model of forming the acoustic beam of 45 ° . By combining acoustic metamaterials and conventional acoustic PA, the model of the active tube array paves a way to design a composite acoustic PA with high radiation efficiency and system robustness without the need for any complex circuit control system. This design concept is expected to be used in the design of ultrasonic therapy devices and high-efficiency transducers.

Leading Gainful Employment Metric Reporting

ERIC Educational Resources Information Center

Powers, Kristina; MacPherson, Derek

2016-01-01

This chapter will address the importance of intercampus involvement in reporting of gainful employment student-level data that will be used in the calculation of gainful employment metrics by the U.S. Department of Education. The authors will discuss why building relationships within the institution is critical for effective gainful employment…

Solar array stepping to minimize array excitation

NASA Technical Reports Server (NTRS)

Bhat, Mahabaleshwar K. P. (Inventor); Liu, Tung Y. (Inventor); Plescia, Carl T. (Inventor)

1989-01-01

Mechanical oscillations of a mechanism containing a stepper motor, such as a solar-array powered spacecraft, are reduced and minimized by the execution of step movements in pairs of steps, the period between steps being equal to one-half of the period of torsional oscillation of the mechanism. Each pair of steps is repeated at needed intervals to maintain desired continuous movement of the portion of elements to be moved, such as the solar array of a spacecraft. In order to account for uncertainty as well as slow change in the period of torsional oscillation, a command unit may be provided for varying the interval between steps in a pair.

Efficient Array Design for Sonotherapy

PubMed Central

Stephens, Douglas N.; Kruse, Dustin E.; Ergun, Arif S.; Barnes, Stephen; Ming Lu, X.; Ferrara, Katherine

2008-01-01

New linear multi-row, multi-frequency arrays have been designed, constructed and tested as fully operational ultrasound probes to produce confocal imaging and therapeutic acoustic intensities with a standard commercial ultrasound imaging system. The triple-array probes and imaging system produce high quality B-mode images with a center row imaging array at 5.3 MHz, and sufficient acoustic power with dual therapeutic arrays to produce mild hyperthermia at 1.54 MHz. The therapeutic array pair in the first probe design (termed G3) utilizes a high bandwidth and peak pressure, suitable for mechanical therapies. The second multi-array design (termed G4) has a redesigned therapeutic array pair which is optimized for high time-averaged power output suitable for mild hyperthermia applications. The “thermal therapy” design produces more than 4 Watts of acoustic power from the low frequency arrays with only a 10.5 °C internal rise in temperature after 100 seconds of continuous use with an unmodified conventional imaging system, or substantially longer operation at lower acoustic power. The low frequency arrays in both probe designs were examined and contrasted for real power transfer efficiency with a KLM model which includes all lossy contributions in the power delivery path from system transmitters to tissue load. Laboratory verification was successfully performed for the KLM derived estimates of transducer parallel model acoustic resistance and dissipation resistance, which are the critical design factors for acoustic power output and undesired internal heating respectively. PMID:18591737

Integrated Array/Metadata Analytics

NASA Astrophysics Data System (ADS)

Misev, Dimitar; Baumann, Peter

2015-04-01

Data comes in various forms and types, and integration usually presents a problem that is often simply ignored and solved with ad-hoc solutions. Multidimensional arrays are an ubiquitous data type, that we find at the core of virtually all science and engineering domains, as sensor, model, image, statistics data. Naturally, arrays are richly described by and intertwined with additional metadata (alphanumeric relational data, XML, JSON, etc). Database systems, however, a fundamental building block of what we call "Big Data", lack adequate support for modelling and expressing these array data/metadata relationships. Array analytics is hence quite primitive or non-existent at all in modern relational DBMS. Recognizing this, we extended SQL with a new SQL/MDA part seamlessly integrating multidimensional array analytics into the standard database query language. We demonstrate the benefits of SQL/MDA with real-world examples executed in ASQLDB, an open-source mediator system based on HSQLDB and rasdaman, that already implements SQL/MDA.

High-power, ultralow-mass solar arrays: FY-77 solar arrays technology readiness assessment report, volume 2

NASA Technical Reports Server (NTRS)

Costogue, E. N.; Young, L. E.; Brandhorst, H. W., Jr.

1978-01-01

Development efforts are reported in detail for: (1) a lightweight solar array system for solar electric propulsion; (2) a high efficiency thin silicon solar cell; (3) conceptual design of 200 W/kg solar arrays; (4) fluorocarbon encapsulation for silicon solar cell array; and (5) technology assessment of concentrator solar arrays.

RGAugury: a pipeline for genome-wide prediction of resistance gene analogs (RGAs) in plants.

PubMed

Li, Pingchuan; Quan, Xiande; Jia, Gaofeng; Xiao, Jin; Cloutier, Sylvie; You, Frank M

2016-11-02

Resistance gene analogs (RGAs), such as NBS-encoding proteins, receptor-like protein kinases (RLKs) and receptor-like proteins (RLPs), are potential R-genes that contain specific conserved domains and motifs. Thus, RGAs can be predicted based on their conserved structural features using bioinformatics tools. Computer programs have been developed for the identification of individual domains and motifs from the protein sequences of RGAs but none offer a systematic assessment of the different types of RGAs. A user-friendly and efficient pipeline is needed for large-scale genome-wide RGA predictions of the growing number of sequenced plant genomes. An integrative pipeline, named RGAugury, was developed to automate RGA prediction. The pipeline first identifies RGA-related protein domains and motifs, namely nucleotide binding site (NB-ARC), leucine rich repeat (LRR), transmembrane (TM), serine/threonine and tyrosine kinase (STTK), lysin motif (LysM), coiled-coil (CC) and Toll/Interleukin-1 receptor (TIR). RGA candidates are identified and classified into four major families based on the presence of combinations of these RGA domains and motifs: NBS-encoding, TM-CC, and membrane associated RLP and RLK. All time-consuming analyses of the pipeline are paralleled to improve performance. The pipeline was evaluated using the well-annotated Arabidopsis genome. A total of 98.5, 85.2, and 100 % of the reported NBS-encoding genes, membrane associated RLPs and RLKs were validated, respectively. The pipeline was also successfully applied to predict RGAs for 50 sequenced plant genomes. A user-friendly web interface was implemented to ease command line operations, facilitate visualization and simplify result management for multiple datasets. RGAugury is an efficiently integrative bioinformatics tool for large scale genome-wide identification of RGAs. It is freely available at Bitbucket: https://bitbucket.org/yaanlpc/rgaugury .

Design of High Impedance Electromagnetic Surfaces for Mutual Coupling Reduction in Patch Antenna Array.

PubMed

Islam, Mohammad Tariqul; Alam, Md Shahidul

2013-01-07

A compact planar meander-bridge high impedance electromagnetic structure (MBHIES) was designed and its bandgap characteristics, mutual coupling reduction abilities were studied and compared in detail. Several parametric analyses were performed to obtain optimized design values and the transmission responses were calculated through the suspended microstrip line and waveguide simulation methods. The achieved bandgap is 2.3 GHz (2.55-4.85 GHz) with -61 dB minimum transmission coefficient level at the center frequency of 3.6 GHz. To see the effectiveness, the proposed design was inserted between a microstrip patch antenna array which operates at 3.8 GHz and whose operating bandwidth falls within the MBHIES bandgap. The surface wave suppression phenomenon was analyzed and simulated results are verified by measuring the fabricated prototypes, both are in good agreement. The configuration reduced the mutual coupling by 20.69 dB in simulation and 19.18 dB in measurement, without affecting the radiation characteristics of the array but increasing the gain slightly.

Wire Array Photovoltaics

NASA Astrophysics Data System (ADS)

Turner-Evans, Dan

Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

Optimal shortening of uniform covering arrays

PubMed Central

Rangel-Valdez, Nelson; Avila-George, Himer; Carrizalez-Turrubiates, Oscar

2017-01-01

Software test suites based on the concept of interaction testing are very useful for testing software components in an economical way. Test suites of this kind may be created using mathematical objects called covering arrays. A covering array, denoted by CA(N; t, k, v), is an N × k array over Zv={0,…,v-1} with the property that every N × t sub-array covers all t-tuples of Zvt at least once. Covering arrays can be used to test systems in which failures occur as a result of interactions among components or subsystems. They are often used in areas such as hardware Trojan detection, software testing, and network design. Because system testing is expensive, it is critical to reduce the amount of testing required. This paper addresses the Optimal Shortening of Covering ARrays (OSCAR) problem, an optimization problem whose objective is to construct, from an existing covering array matrix of uniform level, an array with dimensions of (N − δ) × (k − Δ) such that the number of missing t-tuples is minimized. Two applications of the OSCAR problem are (a) to produce smaller covering arrays from larger ones and (b) to obtain quasi-covering arrays (covering arrays in which the number of missing t-tuples is small) to be used as input to a meta-heuristic algorithm that produces covering arrays. In addition, it is proven that the OSCAR problem is NP-complete, and twelve different algorithms are proposed to solve it. An experiment was performed on 62 problem instances, and the results demonstrate the effectiveness of solving the OSCAR problem to facilitate the construction of new covering arrays. PMID:29267343

Ultralow-Background Large-Format Bolometer Arrays

NASA Technical Reports Server (NTRS)

Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Oegerle, William (Technical Monitor)

2002-01-01

In the coming decade, work will commence in earnest on large cryogenic far-infrared telescopes and interferometers. All such observatories - for example, SAFIR, SPIRIT, and SPECS - require large format, two dimensional arrays of close-packed detectors capable of reaching the fundamental limits imposed by the very low photon backgrounds present in deep space. In the near term, bolometer array architectures which permit 1000 pixels - perhaps sufficient for the next generation of space-based instruments - can be arrayed efficiently. Demonstrating the necessary performance, with Noise Equivalent Powers (NEPs) of order 10-20 W/square root of Hz, will be a hurdle in the coming years. Superconducting bolometer arrays are a promising technology for providing both the performance and the array size necessary. We discuss the requirements for future detector arrays in the far-infrared and submillimeter, describe the parameters of superconducting bolometer arrays able to meet these requirements, and detail the present and near future technology of superconducting bolometer arrays. Of particular note is the coming development of large format planar arrays with absorber-coupled and antenna-coupled bolometers.

Carbon nanotube array based sensor

DOEpatents

Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

2005-09-20

A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

PGDP Trichloroethene Biodegradation Investigation Summary Report: Regional Gravel Aquifer & Northwest Plume

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

Hampson, Steve

The evaluation of biological degradation processes addressed by this report are part of a broad trichloroethene (TCE) Fate and Transport Investigation that includes four (4) topics of phased investigation (Table ES1) relative to degradation and/or attenuation of TCE in the Regional Gravel Aquifer (RGA) underlying the United States Department of Energy Paducah Gaseous Diffusion Plant (PGDP). In order of implementation the project phases are: (1) derivation of a TCE first-order rate constant by normalization of TCE values against technetium-99 ( 99Tc) and chloride. 2) identification of the presence of microbes capable of aerobic co-metabolic TCE biodegradation using enzyme activity probesmore » (this report); 3) Compound-specific isotope analysis (CSIA) to support prevalence of biotic and/or abiotic degradation processes; and 4) evaluation of potential abiotic RGA-TCE attenuation mechanisms including sorption. This report summarizes the Phase II activities related to the identification and evaluation of biological degradation processes that may be actively influencing TCE fate and transport in the RGA contaminant plumes at the United States Department of Energy (DOE) PGDP and its environs (Figure ES1). The goals of these activities were to identify active biological degradation mechanisms in the RGA through multiple lines of evidence and to provide DOE with recommendations for future TCE biological degradation investigations.« less

Shielding in ungated field emitter arrays

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

Harris, J. R.; Jensen, K. L.; Shiffler, D. A.

Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can bemore » used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 10{sup 2}–10{sup 4} are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.« less

Modeling of the gain distribution for diode pumping of a solid-state laser rod with nonimaging optics.

PubMed

Koshel, R J; Walmsley, I A

1993-03-20

We investigate the absorption distribution in a cylindrical gain medium that is pumped by a source of distributed laser diodes by means of a pump cavity developed from the edge-ray principle of nonimaging optics. The performance of this pumping arrangement is studied by using a nonsequential, numerical, three-dimensional ray-tracing scheme. A figure of merit is defined for the pump cavities that takes into account the coupling efficiency and uniformity of the absorption distribution. It is found that the nonimaging pump cavity maintains a high coupling efficiency with extended two-dimensional diode arrays and obtains a fairly uniform absorption distribution. The nonimaging cavity is compared with two other designs: a close-coupled side-pumped cavity and an imaging design in the form of a elliptical cavity. The nonimaging cavity has a better figure of merit per diode than these two designs. It also permits the use of an extended, sparse, two-dimensional diode array, which reduces thermal loading of the source and eliminates all cavity optics other than the main reflector.

Array architectures for iterative algorithms

NASA Technical Reports Server (NTRS)

Jagadish, Hosagrahar V.; Rao, Sailesh K.; Kailath, Thomas

1987-01-01

Regular mesh-connected arrays are shown to be isomorphic to a class of so-called regular iterative algorithms. For a wide variety of problems it is shown how to obtain appropriate iterative algorithms and then how to translate these algorithms into arrays in a systematic fashion. Several 'systolic' arrays presented in the literature are shown to be specific cases of the variety of architectures that can be derived by the techniques presented here. These include arrays for Fourier Transform, Matrix Multiplication, and Sorting.

Sub-electron read noise and millisecond full-frame readout with the near infrared eAPD array SAPHIRA

NASA Astrophysics Data System (ADS)

Finger, Gert; Baker, Ian; Alvarez, Domingo; Dupuy, Christophe; Ives, Derek; Meyer, Manfred; Mehrgan, Leander; Stegmeier, Jörg; Weller, Harald J.

2016-07-01

In 2007 ESO started a program at SELEX (now LEONARDO) to develop noiseless near infrared HgCdTe electron avalanche photodiode arrays (eAPD)[1][2][3]. This eAPD technology is only way to overcome the limiting CMOS noise barrier of near infrared sensors used for wavefront sensing and fringe tracking. After several development cycles of solid state engineering techniques which can be easily applied to the chosen growth technology of metal organic vapour phase epitaxy (MOVPE), the eAPD arrays have matured and resulted in the SAPHIRA arrays. They have a format of 320x256 pixels with a pitch of 24 μm. They now offer an unmatched combination of sub-electron read noise at millisecond frame readout rates. The first generation of SAPHIRA arrays were only sensitive in H and K-band. With the removal of a wide bandgap buffer layer the arrays are now sensitive from λ=0.8 μm to 2.5 μm with high quantum efficiency over the entire wavelength range. The high temperature anneal applied during the growth process produces material with superb cosmetic quality at an APD gain of over 600. The design of the SAPHIRA ROIC has also been revised and the new ME1000 ROIC has an optimized analogue chain and more flexible readout modes. The clock for the vertical shift register is now under external control. The advantage of this is that correlated-double-sampling and uncorrelated readout in the rolling shutter mode now have a duty cycle of 100% at the maximum frame rate. Furthermore, to reduce the readout noise rows can be read several times before and after row reset. Since the APD gain is sufficiently high that one photon produces many more electrons than the square root of kTC which is the charge uncertainty after reset, signals of one photon per exposure can be easily detected without the need for double correlated sampling. First results obtained with the fringe tracker in GRAVITY and the four SAPHIRA wavefront sensors installed in the CIAO adaptive optics systems of the four 8 meter

Photovoltaic array: Power conditioner interface characteristics

NASA Technical Reports Server (NTRS)

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

1982-01-01

The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes.

Human location estimation using thermopile array sensor

NASA Astrophysics Data System (ADS)

Parnin, S.; Rahman, M. M.

2017-11-01

Utilization of Thermopile sensor at an early stage of human detection is challenging as there are many things that produce thermal heat other than human such as electrical appliances and animals. Therefrom, an algorithm for early presence detection has been developed through the study of human body temperature behaviour with respect to the room temperature. The change in non-contact detected temperature of human varied according to body parts. In an indoor room, upper parts of human body change up to 3°C whereas lower part ranging from 0.58°C to 1.71°C. The average changes in temperature of human is used as a conditional set-point value in the program algorithm to detect human presence. The current position of human and its respective angle is gained when human is presence at certain pixels of Thermopile’s sensor array. Human position is estimated successfully as the developed sensory system is tested to the actuator of a stand fan.

Theory for optimal design of waveguiding light concentrators in photovoltaic microcell arrays.

PubMed

Semichaevsky, Andrey V; Johnson, Harley T; Yoon, Jongseung; Nuzzo, Ralph G; Li, Lanfang; Rogers, John

2011-06-10

Efficiency of ultrathin flexible solar photovoltaic silicon microcell arrays can be significantly improved using nonimaging solar concentrators. A fluorophore is introduced to match the solar spectrum and the low-reflectivity wavelength range of Si, reduce the escape losses, and allow the nontracking operation. In this paper we optimize our solar concentrators using a luminescent/nonluminescent photon transport model. Key modeling results are compared quantitatively to experiments and are in good agreement with the latter. Our solar concentrator performance is not limited by the dye self-absorption. Bending deformations of the flexible solar collectors do not result in their indirect gain degradation compared to flat solar concentrators with the same projected area.

A Multi-Functional Microelectrode Array Featuring 59760 Electrodes, 2048 Electrophysiology Channels, Stimulation, Impedance Measurement and Neurotransmitter Detection Channels.

PubMed

Dragas, Jelena; Viswam, Vijay; Shadmani, Amir; Chen, Yihui; Bounik, Raziyeh; Stettler, Alexander; Radivojevic, Milos; Geissler, Sydney; Obien, Marie; Müller, Jan; Hierlemann, Andreas

2017-06-01

Biological cells are characterized by highly complex phenomena and processes that are, to a great extent, interdependent. To gain detailed insights, devices designed to study cellular phenomena need to enable tracking and manipulation of multiple cell parameters in parallel; they have to provide high signal quality and high spatiotemporal resolution. To this end, we have developed a CMOS-based microelectrode array system that integrates six measurement and stimulation functions, the largest number to date. Moreover, the system features the largest active electrode array area to date (4.48×2.43 mm 2 ) to accommodate 59,760 electrodes, while its power consumption, noise characteristics, and spatial resolution (13.5 μm electrode pitch) are comparable to the best state-of-the-art devices. The system includes: 2,048 action-potential (AP, bandwidth: 300 Hz to 10 kHz) recording units, 32 local-field-potential (LFP, bandwidth: 1 Hz to 300 Hz) recording units, 32 current recording units, 32 impedance measurement units, and 28 neurotransmitter detection units, in addition to the 16 dual-mode voltage-only or current/voltage-controlled stimulation units. The electrode array architecture is based on a switch matrix, which allows for connecting any measurement/stimulation unit to any electrode in the array and for performing different measurement/stimulation functions in parallel.

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

PubMed Central

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-01-01

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s. PMID:26950128

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System.

PubMed

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-03-02

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

Invention and Gain Analysis.

ERIC Educational Resources Information Center

Weber, Robert J.; Dixon, Stacey

1989-01-01

Gain analysis is applied to the invention of the sewing needle as well as different sewing implements and modes of sewing. The analysis includes a two-subject experiment. To validate the generality of gain heuristics and underlying switching processes, the invention of the assembly line is also analyzed. (TJH)

Low power, highly linear output buffer. [for infrared focal plane arrays

NASA Technical Reports Server (NTRS)

Foley, D.; Butler, N.; Stobie, J.

1992-01-01

A class AB CMOS output buffer has been designed for use on an IR focal plane array. Given the requirements for power dissipation and load capacitance a class A output, such as a source follower, would be unsuitable. The approach taken uses a class AB amplifier configured as a charge integrator. Thus it converts a charge packet in the focal plane multiplexer to a voltage which is then the output of the focal plane. With a quiescent current of 18 micro-a and a load capacitance of 100 pf, the amplifier has an open loop unity gain bandwidth of 900 khz. Integral nonlinearity is better than .03 percent over 5.5 volts when run with VDD-VSS = 6v.

Resolution of Port/Starboard Ambiguity Using a Linear Array of Triplets and a Twin-Line Planar Array

DTIC Science & Technology

2016-06-01

STARBOARD AMBIGUITY USING A LINEAR ARRAY OF TRIPLETS AND A TWIN- LINE PLANAR ARRAY by Stilson Veras Cardoso June 2016 Thesis Advisor...OF TRIPLETS AND A TWIN-LINE PLANAR ARRAY 5. FUNDING NUMBERS 6. AUTHOR(S) Stilson Veras Cardoso 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...A LINEAR ARRAY OF TRIPLETS AND A TWIN-LINE PLANAR ARRAY Stilson Veras Cardoso Civilian, Brazilian Navy B.S., University of Brasília, 1993

Comparative Genomic Hybridization–Array Analysis Enhances the Detection of Aneuploidies and Submicroscopic Imbalances in Spontaneous Miscarriages

PubMed Central

Schaeffer, Anthony J. ; Chung, June ; Heretis, Konstantina ; Wong, Andrew ; Ledbetter, David H. ; Lese Martin, Christa 

2004-01-01

Miscarriage is a condition that affects 10%–15% of all clinically recognized pregnancies, most of which occur in the first trimester. Approximately 50% of first-trimester miscarriages result from fetal chromosome abnormalities. Currently, G-banded chromosome analysis is used to determine if large-scale genetic imbalances are the cause of these pregnancy losses. This technique relies on the culture of cells derived from the fetus, a technique that has many limitations, including a high rate of culture failure, maternal overgrowth of fetal cells, and poor chromosome morphology. Comparative genomic hybridization (CGH)–array analysis is a powerful new molecular cytogenetic technique that allows genomewide analysis of DNA copy number. By hybridizing patient DNA and normal reference DNA to arrays of genomic clones, unbalanced gains or losses of genetic material across the genome can be detected. In this study, 41 product-of-conception (POC) samples, which were previously analyzed by G-banding, were tested using CGH arrays to determine not only if the array could identify all reported abnormalities, but also whether any previously undetected genomic imbalances would be discovered. The array methodology detected all abnormalities as reported by G-banding analysis and revealed new abnormalities in 4/41 (9.8%) cases. Of those, one trisomy 21 POC was also mosaic for trisomy 20, one had a duplication of the 10q telomere region, one had an interstitial deletion of chromosome 9p, and the fourth had an interstitial duplication of the Prader-Willi/Angelman syndrome region on chromosome 15q, which, if maternally inherited, has been implicated in autism. This retrospective study demonstrates that the DNA-based CGH-array technology overcomes many of the limitations of routine cytogenetic analysis of POC samples while enhancing the detection of fetal chromosome aberrations. PMID:15127362

Integrated residential photovoltaic array development

NASA Technical Reports Server (NTRS)

Shepard, N. F., Jr.

1981-01-01

Three basic module design concepts were analyzed with respect to both production and installation costs. The results of this evaluation were used to synthesize a fourth design which incorporates the best features of these initial concepts to produce a module/array design approach which offers the promise of a substantial reduction in the installed cost of a residential array. A unique waterproofing and mounting scheme was used to reduce the cost of installing an integral array while still maintaining a high probability that the installed array will be watertight for the design lifetime of the system. This recommended concept will also permit the array to be mounted as a direct or stand-off installation with no changes to the module design.

Characterization of Charge Separation in the Array of Micromachined UltraSonic Electrospray (AMUSE) Ion Source for Mass Spectrometry

PubMed Central

Forbes, Thomas P.; Dixon, R. Brent; Muddiman, David C.; Degertekin, F. Levent; Fedorov, Andrei G.

2009-01-01

An initial investigation into the effects of charge separation in the Array of Micromachined UltraSonic Electrospray (AMUSE) ion source is reported in order to gain understanding of ionization mechanisms and to improve analyte ionization efficiency and operation stability. In RF-only mode, AMUSE ejects on average, an equal number of slightly positive and slightly negative charged droplets due to random charge fluctuations, providing inefficient analyte ionization. Charge separation at the nozzle orifice is achieved by the application of an external electric field. By bringing the counter electrode close to the nozzle array, strong electric fields can be applied at relatively low DC potentials. It has been demonstrated, through a number of electrode/electrical potential configurations that increasing charge separation leads to improvement in signal abundance, signal-to-noise ratio, and signal stability. PMID:19525123

Characterization of charge separation in the Array of Micromachined UltraSonic Electrospray (AMUSE) ion source for mass spectrometry.

PubMed

Forbes, Thomas P; Dixon, R Brent; Muddiman, David C; Degertekin, F Levent; Fedorov, Andrei G

2009-09-01

An initial investigation into the effects of charge separation in the Array of Micromachined UltraSonic Electrospray (AMUSE) ion source is reported to gain understanding of ionization mechanisms and to improve analyte ionization efficiency and operation stability. In RF-only mode, AMUSE ejects, on average, an equal number of slightly positive and slightly negative charged droplets due to random charge fluctuations, providing inefficient analyte ionization. Charge separation at the nozzle orifice is achieved by the application of an external electric field. By bringing the counter electrode close to the nozzle array, strong electric fields can be applied at relatively low DC potentials. It has been demonstrated, through a number of electrode/electrical potential configurations, that increasing charge separation leads to improvement in signal abundance, signal-to-noise ratio, and signal stability.

The hyperion particle-γ detector array

DOE PAGES

Hughes, R. O.; Burke, J. T.; Casperson, R. J.; ...

2017-03-08

Hyperion is a new high-efficiency charged-particle γ-ray detector array which consists of a segmented silicon telescope for charged-particle detection and up to fourteen high-purity germanium clover detectors for the detection of coincident γ rays. The array will be used in nuclear physics measurements and Stockpile Stewardship studies and replaces the STARLiTeR array. In conclusion, this article discusses the features of the array and presents data collected with the array in the commissioning experiment.

Circuit design for the retina-like image sensor based on space-variant lens array

NASA Astrophysics Data System (ADS)

Gao, Hongxun; Hao, Qun; Jin, Xuefeng; Cao, Jie; Liu, Yue; Song, Yong; Fan, Fan

2013-12-01

Retina-like image sensor is based on the non-uniformity of the human eyes and the log-polar coordinate theory. It has advantages of high-quality data compression and redundant information elimination. However, retina-like image sensors based on the CMOS craft have drawbacks such as high cost, low sensitivity and signal outputting efficiency and updating inconvenience. Therefore, this paper proposes a retina-like image sensor based on space-variant lens array, focusing on the circuit design to provide circuit support to the whole system. The circuit includes the following parts: (1) A photo-detector array with a lens array to convert optical signals to electrical signals; (2) a strobe circuit for time-gating of the pixels and parallel paths for high-speed transmission of the data; (3) a high-precision digital potentiometer for the I-V conversion, ratio normalization and sensitivity adjustment, a programmable gain amplifier for automatic generation control(AGC), and a A/D converter for the A/D conversion in every path; (4) the digital data is displayed on LCD and stored temporarily in DDR2 SDRAM; (5) a USB port to transfer the data to PC; (6) the whole system is controlled by FPGA. This circuit has advantages as lower cost, larger pixels, updating convenience and higher signal outputting efficiency. Experiments have proved that the grayscale output of every pixel basically matches the target and a non-uniform image of the target is ideally achieved in real time. The circuit can provide adequate technical support to retina-like image sensors based on space-variant lens array.

College Freshmen Students' Perspectives on Weight Gain Prevention in the Digital Age: Web-Based Survey.

PubMed

Monroe, Courtney M; Turner-McGrievy, Gabrielle; Larsen, Chelsea A; Magradey, Karen; Brandt, Heather M; Wilcox, Sara; Sundstrom, Beth; West, Delia Smith

2017-10-12

healthy diet and staying physically active). Email was the most frequently used electronic platform, with 96% (48/50) of students reporting current use of it. Email was also the most frequently cited preferred eHealth delivery platform, with 86% (43/50) of students selecting it. Facebook was preferred by the second greatest proportion of students (40%, 20/50). Most college freshmen have concerns about an array of weight gain prevention topics and are generally open to the possibility of receiving eHealth interventions designed to address their concerns, preferably via email compared with popular social media platforms. These preliminary findings offer a foundation to build upon when it comes to future descriptive investigations focused on behavioral weight gain prevention among college freshmen in the digital age. ©Courtney M Monroe, Gabrielle Turner-McGrievy, Chelsea A Larsen, Karen Magradey, Heather M Brandt, Sara Wilcox, Beth Sundstrom, Delia Smith West. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 12.10.2017.

Loop gain stabilizing with an all-digital automatic-gain-control method for high-precision fiber-optic gyroscope.

PubMed

Zheng, Yue; Zhang, Chunxi; Li, Lijing; Song, Lailiang; Chen, Wen

2016-06-10

For a fiber-optic gyroscope (FOG) using electronic dithers to suppress the dead zone, without a fixed loop gain, the deterministic compensation for the dither signals in the control loop of the FOG cannot remain accurate, resulting in the dither residuals in the FOG rotation rate output and the navigation errors in the inertial navigation system. An all-digital automatic-gain-control method for stabilizing the loop gain of the FOG is proposed. By using a perturbation square wave to measure the loop gain of the FOG and adding an automatic gain control loop in the conventional control loop of the FOG, we successfully obtain the actual loop gain and make the loop gain converge to the reference value. The experimental results show that in the case of 20% variation in the loop gain, the dither residuals are successfully eliminated and the standard deviation of the FOG sampling outputs is decreased from 2.00  deg/h to 0.62  deg/h (sampling period 2.5 ms, 10 points smoothing). With this method, the loop gain of the FOG can be stabilized over the operation temperature range and in the long-time application, which provides a solid foundation for the engineering applications of the high-precision FOG.

Fill-factor improvement of Si CMOS single-photon avalanche diode detector arrays by integration of diffractive microlens arrays.

PubMed

Intermite, Giuseppe; McCarthy, Aongus; Warburton, Ryan E; Ren, Ximing; Villa, Federica; Lussana, Rudi; Waddie, Andrew J; Taghizadeh, Mohammad R; Tosi, Alberto; Zappa, Franco; Buller, Gerald S

2015-12-28

Single-photon avalanche diode (SPAD) detector arrays generally suffer from having a low fill-factor, in which the photo-sensitive area of each pixel is small compared to the overall area of the pixel. This paper describes the integration of different configurations of high efficiency diffractive optical microlens arrays onto a 32 × 32 SPAD array, fabricated using a 0.35 µm CMOS technology process. The characterization of SPAD arrays with integrated microlens arrays is reported over the spectral range of 500-900 nm, and a range of f-numbers from f/2 to f/22. We report an average concentration factor of 15 measured for the entire SPAD array with integrated microlens array. The integrated SPAD and microlens array demonstrated a very high uniformity in overall efficiency.

Maskless wafer-level microfabrication of optical penetrating neural arrays out of soda-lime glass: Utah Optrode Array.

PubMed

Boutte, Ronald W; Blair, Steve

2016-12-01

Borrowing from the wafer-level fabrication techniques of the Utah Electrode Array, an optical array capable of delivering light for neural optogenetic studies is presented in this paper: the Utah Optrode Array. Utah Optrode Arrays are micromachined out of sheet soda-lime-silica glass using standard backend processes of the semiconductor and microelectronics packaging industries such as precision diamond grinding and wet etching. 9 × 9 arrays with 1100μ m × 100μ m optrodes and a 500μ m back-plane are repeatably reproduced on 2i n wafers 169 arrays at a time. This paper describes the steps and some of the common errors of optrode fabrication.

Phased Array-Fed Reflector (PAFR) Antenna Architectures for Space-Based Sensors

NASA Technical Reports Server (NTRS)

Cooley, Michael E.

2014-01-01

Communication link and target ranges for satellite communications (SATCOM) and space-based sensors (e.g. radars) vary from approximately 1000 km (for LEO satellites) to 35,800 km (for GEO satellites). At these long ranges, large antenna gains are required and legacy payloads have usually employed large reflectors with single beams that are either fixed or mechanically steered. For many applications, there are inherent limitations that are associated with the use of these legacy antennas/payloads. Hybrid antenna designs using Phased Array Fed Reflectors (PAFRs) provide a compromise between reflectors and Direct Radiating phased Arrays (DRAs). PAFRs provide many of the performance benefits of DRAs while utilizing much smaller, lower cost (feed) arrays. The primary limitation associated with hybrid PAFR architectures is electronic scan range; approximately +/-5 to +/- 10 degrees is typical, but this range depends on many factors. For LEO applications, the earth FOV is approximately +/-55 degrees which is well beyond the range of electronic scanning for PAFRs. However, for some LEO missions, limited scanning is sufficient or the CONOPS and space vehicle designs can be developed to incorporate a combination mechanical slewing and electronic scanning. In this paper, we review, compare and contrast various PAFR architectures with a focus on their general applicability to space missions. We compare the RF performance of various PAFR architectures and describe key hardware design and implementation trades. Space-based PAFR designs are highly multi-disciplinary and we briefly address key hardware engineering design areas. Finally, we briefly describe two PAFR antenna architectures that have been developed at Northrop Grumman.

The Precision Array for Probing the Epoch of Re-ionization: Eight Station Results

NASA Astrophysics Data System (ADS)

Parsons, Aaron R.; Backer, Donald C.; Foster, Griffin S.; Wright, Melvyn C. H.; Bradley, Richard F.; Gugliucci, Nicole E.; Parashare, Chaitali R.; Benoit, Erin E.; Aguirre, James E.; Jacobs, Daniel C.; Carilli, Chris L.; Herne, David; Lynch, Mervyn J.; Manley, Jason R.; Werthimer, Daniel J.

2010-04-01

We are developing the Precision Array for Probing the Epoch of Re-ionization (PAPER) to detect 21 cm emission from the early universe, when the first stars and galaxies were forming. We describe the overall experiment strategy and architecture and summarize two PAPER deployments: a four-antenna array in the low radio frequency interference (RFI) environment of Western Australia and an eight-antenna array at a prototyping site at the NRAO facilities near Green Bank, WV. From these activities we report on system performance, including primary beam model verification, dependence of system gain on ambient temperature, measurements of receiver and overall system temperatures, and characterization of the RFI environment at each deployment site. We present an all-sky map synthesized between 139 MHz and 174 MHz using data from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5 sr at 156 MHz), with a 10 mJy (620 mK) thermal noise level that indicates what would be achievable with better foreground subtraction. We calculate angular power spectra (C ell) in a cold patch and determine them to be dominated by point sources, but with contributions from galactic synchrotron emission at lower radio frequencies and angular wavemodes. Although the sample variance of foregrounds dominates errors in these power spectra, we measure a thermal noise level of 310 mK at ell = 100 for a 1.46 MHz band centered at 164.5 MHz. This sensitivity level is approximately 3 orders of magnitude in temperature above the level of the fluctuations in 21 cm emission associated with re-ionization.

Weight gain following treatment of hyperthyroidism.

PubMed

Dale, J; Daykin, J; Holder, R; Sheppard, M C; Franklyn, J A

2001-08-01

Patients frequently express concern that treating hyperthyroidism will lead to excessive weight gain. This study aimed to determine the extent of, and risk factors for, weight gain in an unselected group of hyperthyroid patients. We investigated 162 consecutive hyperthyroid patients followed for at least 6 months. Height, weight, clinical features, biochemistry and management were recorded at each clinic visit. Documented weight gain was 5.42 +/- 0.46 kg (mean +/- SE) and increase in BMI was 8.49 +/- 0.71%, over a mean 24.2 +/- 1.6 months. Pre-existing obesity, Graves' disease causing hyperthyroidism, weight loss before presentation and length of follow-up each independently predicted weight gain. Patients treated with thionamides or radioiodine gained a similar amount of weight (thionamides, n = 87, 5.16 +/- 0.63 kg vs. radioiodine, n = 62, 4.75 +/- 0.57 kg, P = 0.645), but patients who underwent thyroidectomy (n = 13) gained more weight (10.27 +/- 2.56 kg vs. others, P = 0.007). Development of hypothyroidism (even transiently) was associated with weight gain (never hypothyroid, n = 102, 4.57 +/- 0.52 kg, transiently hypothyroid, n = 29, 5.37 +/- 0.85 kg, on T4, n = 31, 8.06 +/- 1.42 kg, P = 0.014). This difference remained after correcting for length of follow-up. In the whole cohort, weight increased by 3.95 +/- 0.40 kg at 1 year (n = 144) to 9.91 +/- 1.62 kg after 4 years (n = 27) (P = 0.008), representing a mean weight gain of 3.66 +/- 0.44 kg/year. We have demonstrated marked weight gain after treatment of hyperthyroidism. Pre-existing obesity, a diagnosis of Graves' disease and prior weight loss independently predicted weight gain and weight continued to rise with time. Patients who became hypothyroid, despite T4 replacement, gained most weight.

Study of gain-coupled distributed feedback laser based on high order surface gain-coupled gratings

NASA Astrophysics Data System (ADS)

Gao, Feng; Qin, Li; Chen, Yongyi; Jia, Peng; Chen, Chao; Cheng, LiWen; Chen, Hong; Liang, Lei; Zeng, Yugang; Zhang, Xing; Wu, Hao; Ning, Yongqiang; Wang, Lijun

2018-03-01

Single-longitudinal-mode, gain-coupled distributed feedback (DFB) lasers based on high order surface gain-coupled gratings are achieved. Periodic surface metal p-contacts with insulated grooves realize gain-coupled mechanism. To enhance gain contrast in the quantum wells without the introduction of effective index-coupled effect, groove length and depth were well designed. Our devices provided a single longitudinal mode with the maximum CW output power up to 48.8 mW/facet at 971.31 nm at 250 mA without facet coating, 3dB linewidth (<3.2 pm) and SMSR (>39 dB). Optical bistable characteristic was observed with a threshold current difference. Experimentally, devices with different cavity lengths were contrasted on power-current and spectrum characteristics. Due to easy fabrication technique and stable performance, it provides a method of fabricating practical gain-coupled distributed feedback lasers for commercial applications.

SWIR HgCdTe avalanche photiode focal plane array performances evaluation

NASA Astrophysics Data System (ADS)

de Borniol, E.; Rothman, J.; Salveti, F.; Feautrier, P.

2017-11-01

One of the main challenges of modern astronomical instruments like adaptive optics (AO) systems or fringe trackers is to deal with the very low photons flux detection scenarios. The typical timescale of atmospheric turbulences being in the range of some tens of milliseconds, infrared wavefront sensors for AO systems needs frame rates higher than 1 KHz leading to integration times lower than 1 ms. This integration time associated with a low irradiance results in a few number of integrated photons per frame per pixel. To preserve the information coming from this weak signal, the focal plane array (FPA) has to present a low read out noise, a high quantum efficiency and a low dark current. Up to now, the output noise of high speed near infrared sensors is limited by the silicon read out circuit noise. The use of HgCdTe avalanche photodiodes with high gain at moderate reverse bias and low excess noise seems then a logical way to reduce the impact of the read noise on images signal to noise ratio. These low irradiance passive imaging applications with integration times in the millisecond range needs low photodiode dark current and low background current. These requirements lead to the choice of the photodiode cut off wavelength. The short wave infrared (SWIR) around 3 μm is a good compromise between the gain that can be obtain for a given APD bias and the background and dark current. The CEA LETI HgCdTe APD technology, and a fine analysis of the gain curve characteristic are presented in [1] and won't be detailed here. The response time of the APD is also a key factor for a high frame rate FPA. This parameter has been evaluated in [2] and the results shows cut off frequencies in the GHz range. In this communication we report the performances of a SWIR APD FPA designed and fabricated by CEA LETI and SOFRADIR for astrophysical applications. This development was made in the frame of RAPID, a 4 years R&D project funded by the French FUI (Fond Unique Interministériel). This

Transgenic Cavendish bananas with resistance to Fusarium wilt tropical race 4.

PubMed

Dale, James; James, Anthony; Paul, Jean-Yves; Khanna, Harjeet; Smith, Mark; Peraza-Echeverria, Santy; Garcia-Bastidas, Fernando; Kema, Gert; Waterhouse, Peter; Mengersen, Kerrie; Harding, Robert

2017-11-14

Banana (Musa spp.) is a staple food for more than 400 million people. Over 40% of world production and virtually all the export trade is based on Cavendish banana. However, Cavendish banana is under threat from a virulent fungus, Fusarium oxysporum f. sp. cubense tropical race 4 (TR4) for which no acceptable resistant replacement has been identified. Here we report the identification of transgenic Cavendish with resistance to TR4. In our 3-year field trial, two lines of transgenic Cavendish, one transformed with RGA2, a gene isolated from a TR4-resistant diploid banana, and the other with a nematode-derived gene, Ced9, remain disease free. Transgene expression in the RGA2 lines is strongly correlated with resistance. Endogenous RGA2 homologs are also present in Cavendish but are expressed tenfold lower than that in our most resistant transgenic line. The expression of these homologs can potentially be elevated through gene editing, to provide non-transgenic resistance.

Pyroelectric detector arrays

NASA Technical Reports Server (NTRS)

Fripp, A. L.; Robertson, J. B.; Breckenridge, R. (Inventor)

1982-01-01

A pyroelectric detector array and the method for using it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strips. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

Analytical Performance of a Venturi-assisted Array of Micromachined UltraSonic Electrosprays (AMUSE) Coupled to Ion Trap Mass Spectrometry for the Analysis of Peptides and Proteins

PubMed Central

Hampton, Christina Y.; Forbes, Thomas P.; Varady, Mark J.; Meacham, J. Mark; Fedorov, Andrei G.; Degertekin, F. Levent; Fernández, Facundo M.

2008-01-01

The analytical characterization of a novel ion source for mass spectrometry named Array of Micromachined UltraSonic Electrosprays (AMUSE) is presented here. This is a fundamentally different type of ion generation device, consisting of three major components: 1) a piezoelectric transducer that creates ultrasonic waves at one of the resonant frequencies of the sample-filled device, 2) an array of pyramidally-shaped nozzles micromachined on a silicon wafer, and 3) a spacer which prevents contact between the array and transducer ensuring the transfer of acoustic energy to the sample. A high pressure gradient generated at the apices of the nozzle pyramids forces the periodic ejection of multiple droplet streams from the device. With this device, the processes of droplet formation and droplet charging are separated, hence, the limitations of conventional electrospray-type ion sources, including the need for high charging potentials and the addition of organic solvent to decrease surface tension can be avoided. In this work, a Venturi device is coupled with AMUSE in order to increase desolvation, droplet focusing, and signal stability. Results show that ionization of model peptides and small tuning molecules is possible with DC charging potentials of 100 VDC or less. Ionization in RF-only mode (without DC biasing) was also possible. It was observed that, when combined with AMUSE, the Venturi device provides a 10-fold gain in signal-to-noise ratio for 90% aqueous sample solutions. Further reduction in the diameter of the orifices of the micromachined arrays, led to an additional signal gain of at least 3 orders of magnitude, a 2- to 10-fold gain in the signal-to-noise ratio, and an improvement in signal stability from 47% to 8.5% RSD. The effectiveness of this device for the soft ionization of model proteins in aqueous media, such as cytochrome C was also examined, yielding spectra with an average charge state of 8.8 when analyzed with a 100 VDC charging potential

Bilinearization of the generalized coupled nonlinear Schrödinger equation with variable coefficients and gain and dark-bright pair soliton solutions.

PubMed

Chakraborty, Sushmita; Nandy, Sudipta; Barthakur, Abhijit

2015-02-01

We investigate coupled nonlinear Schrödinger equations (NLSEs) with variable coefficients and gain. The coupled NLSE is a model equation for optical soliton propagation and their interaction in a multimode fiber medium or in a fiber array. By using Hirota's bilinear method, we obtain the bright-bright, dark-bright combinations of a one-soliton solution (1SS) and two-soliton solutions (2SS) for an n-coupled NLSE with variable coefficients and gain. Crucial properties of two-soliton (dark-bright pair) interactions, such as elastic and inelastic interactions and the dynamics of soliton bound states, are studied using asymptotic analysis and graphical analysis. We show that a bright 2-soliton, in addition to elastic interactions, also exhibits multiple inelastic interactions. A dark 2-soliton, on the other hand, exhibits only elastic interactions. We also observe a breatherlike structure of a bright 2-soliton, a feature that become prominent with gain and disappears as the amplitude acquires a minimum value, and after that the solitons remain parallel. The dark 2-soliton, however, remains parallel irrespective of the gain. The results found by us might be useful for applications in soliton control, a fiber amplifier, all optical switching, and optical computing.

Dissecting mitochondrial apoptosis pathways by gain-of-function cell culture screens.

PubMed

Grimm, Stefan

2013-05-01

While more primitive organism such as Caenorhabditis elegans and Drosophila melanogaster feature a limited, and by now probably mostly known, array of basic cell death factors, the mammalian cell is replete with additional regulators of the cell's demise. This abundance of apoptosis mediators has made it imperative to set up a systematic inventory of mammalian cell death genes. Genetic screens in this biological system have recently uncovered the rich diversity of cell death signalling and have in particular highlighted mitochondria as an organelle loaded with apoptosis regulators. Many of the screens that have addressed this utilised the novel technique of RNA interference but some also looked at gain-of-functions with transfected cDNAs. Here we give an overview of the rationale for the latter approach, present the genes discovered by this strategy and in particular describe the involvement of mitochondria and their signalling pathways defined by those genes. Copyright © 2012 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

The CHROMA focal plane array: a large-format, low-noise detector optimized for imaging spectroscopy

NASA Astrophysics Data System (ADS)

Demers, Richard T.; Bailey, Robert; Beletic, James W.; Bernd, Steve; Bhargava, Sidharth; Herring, Jason; Kobrin, Paul; Lee, Donald; Pan, Jianmei; Petersen, Anders; Piquette, Eric; Starr, Brian; Yamamoto, Matthew; Zandian, Majid

2013-09-01

The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne's latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.

Blind calibration of radio interferometric arrays using sparsity constraints and its implications for self-calibration

NASA Astrophysics Data System (ADS)

Chiarucci, Simone; Wijnholds, Stefan J.

2018-02-01

Blind calibration, i.e. calibration without a priori knowledge of the source model, is robust to the presence of unknown sources such as transient phenomena or (low-power) broad-band radio frequency interference that escaped detection. In this paper, we present a novel method for blind calibration of a radio interferometric array assuming that the observed field only contains a small number of discrete point sources. We show the huge computational advantage over previous blind calibration methods and we assess its statistical efficiency and robustness to noise and the quality of the initial estimate. We demonstrate the method on actual data from a Low-Frequency Array low-band antenna station showing that our blind calibration is able to recover the same gain solutions as the regular calibration approach, as expected from theory and simulations. We also discuss the implications of our findings for the robustness of regular self-calibration to poor starting models.

Integrated residential photovoltaic array development

NASA Technical Reports Server (NTRS)

Royal, G. C., III

1981-01-01

Sixteen conceptual designs of residential photovoltaic arrays are described. Each design concept was evaluated by an industry advisory panel using a comprehensive set of technical, economic and institutional criteria. Key electrical and mechanical concerns that effect further array subsystem development are also discussed. Three integrated array design concepts were selected by the advisory panel for further optimization and development. From these concepts a single one will be selected for detailed analysis and prototype fabrication. The three concepts selected are: (1) An array of frameless panels/modules sealed in a T shaped zipper locking neoprene gasket grid pressure fitted into an extruded aluminum channel grid fastened across the rafters. (2) An array of frameless modules pressure fitted in a series of zipper locking EPDM rubber extrusions adhesively bonded to the roof. Series string voltage is developed using a set of integral tongue connectors and positioning blocks. (3) An array of frameless modules sealed by a silicone adhesive in a prefabricated grid of rigid tape and sheet metal attached to the roof.

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.

A 63 element 1.75 dimensional ultrasound phased array for the treatment of benign prostatic hyperplasia

PubMed Central

Saleh, Khaldon Y; Smith, Nadine Barrie

2005-01-01

Background Prostate cancer and benign prostatic hyperplasia are very common diseases in older American men, thus having a reliable treatment modality for both diseases is of great importance. The currently used treating options, mainly surgical ones, have numerous complications, which include the many side effects that accompany such procedures, besides the invasive nature of such techniques. Focused ultrasound is a relatively new treating modality that is showing promising results in treating prostate cancer and benign prostatic hyperplasia. Thus this technique is gaining more attention in the past decade as a non-invasive method to treat both diseases. Methods In this paper, the design, construction and evaluation of a 1.75 dimensional ultrasound phased array to be used for treating prostate cancer and benign prostatic hyperplasia is presented. With this array, the position of the focus can be controlled by changing the electrical power and phase to the individual elements for electronically focusing and steering in a three dimensional volume. The array was designed with a maximum steering angle of ± 13.5° in the transverse direction and a maximum depth of penetration of 11 cm, which allows the treatment of large prostates. The transducer piezoelectric ceramic, matching layers and cable impedance have been designed for maximum power transfer to tissue. Results To verify the capability of the transducer for focusing and steering, exposimetry was performed and the results correlated well with the calculated field. Ex vivo experiments using bovine tissue were performed with various lesion sizes and indicated the capability of the transducer to ablate tissue using short sonications. Conclusion A 1.75 dimensional array, that overcame the drawbacks associated with one-dimensional arrays, has been designed, built and successfully tested. Design issues, such as cable and ceramic capacitances, were taken into account when designing this array. The final prototype

SCINTILLATION ARCS IN LOW-FREQUENCY OBSERVATIONS OF THE TIMING-ARRAY MILLISECOND PULSAR PSR J0437–4715

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

Bhat, N. D. R.; Ord, S. M.; Tremblay, S. E.

2016-02-10

Low-frequency observations of pulsars provide a powerful means for probing the microstructure in the turbulent interstellar medium (ISM). Here we report on high-resolution dynamic spectral analysis of our observations of the timing-array millisecond pulsar PSR J0437–4715 with the Murchison Widefield Array (MWA), enabled by our recently commissioned tied-array beam processing pipeline for voltage data recorded from the high time resolution mode of the MWA. A secondary spectral analysis reveals faint parabolic arcs akin to those seen in high-frequency observations of pulsars with the Green Bank and Arecibo telescopes. Data from Parkes observations at a higher frequency of 732 MHz revealmore » a similar parabolic feature with a curvature that scales approximately as the square of the observing wavelength (λ{sup 2}) to the MWA's frequency of 192 MHz. Our analysis suggests that scattering toward PSR J0437–4715 predominantly arises from a compact region about 115 pc from the Earth, which matches well with the expected location of the edge of the Local Bubble that envelopes the local Solar neighborhood. As well as demonstrating new and improved pulsar science capabilities of the MWA, our analysis underscores the potential of low-frequency pulsar observations for gaining valuable insights into the local ISM and for characterizing the ISM toward timing-array pulsars.« less

Stressed detector arrays for airborne astronomy

NASA Technical Reports Server (NTRS)

Stacey, G. J.; Beeman, J. W.; Haller, E. E.; Geis, N.; Poglitsch, A.; Rumitz, M.

1989-01-01

The development of stressed Ge:Ga detector arrays for far-infrared astronomy from the Kuiper Airborne Observatory (KAO) is discussed. Researchers successfully constructed and used a three channel detector array on five flights from the KAO, and have conducted laboratory tests of a two-dimensional, 25 elements (5x5) detector array. Each element of the three element array performs as well as the researchers' best single channel detector, as do the tested elements of the 25 channel system. Some of the exciting new science possible with far-infrared detector arrays is also discussed.

Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

NASA Astrophysics Data System (ADS)

Aspinall, Michael D.; Jones, Ashley R.

2018-01-01

Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

DNA copy number gains at loci of growth factors and their receptors in salivary gland adenoid cystic carcinoma.

PubMed

Vékony, Hedy; Ylstra, Bauke; Wilting, Saskia M; Meijer, Gerrit A; van de Wiel, Mark A; Leemans, C René; van der Waal, Isaäc; Bloemena, Elisabeth

2007-06-01

Adenoid cystic carcinoma (ACC) is a malignant salivary gland tumor with a high mortality rate due to late, distant metastases. This study aimed at unraveling common genetic abnormalities associated with ACC. Additionally, chromosomal changes were correlated with patient characteristics and survival. Microarray-based comparative genomic hybridization was done to a series of 18 paraffin-embedded primary ACCs using a genome-wide scanning BAC array. A total of 238 aberrations were detected, representing more gains than losses (205 versus 33, respectively). Most frequent gains (>60%) were observed at 9q33.3-q34.3, 11q13.3, 11q23.3, 19p13.3-p13.11, 19q12-q13.43, 21q22.3, and 22q13.33. These loci harbor numerous growth factor [fibroblast growth factor (FGF) and platelet-derived growth factor (PDGF)] and growth factors receptor (FGFR3 and PDGFRbeta) genes. Gains at the FGF(R) regions occurred significantly more frequently in the recurred/metastasized ACCs compared with indolent ACCs. Furthermore, patients with 17 or more chromosomal aberrations had a significantly less favorable outcome than patients with fewer chromosomal aberrations (log-rank = 5.2; P = 0.02). Frequent DNA copy number gains at loci of growth factors and their receptors suggest their involvement in ACC initiation and progression. Additionally, the presence of FGFR3 and PDGFRbeta in increased chromosomal regions suggests a possible role for autocrine stimulation in ACC tumorigenesis.

Optimization of control gain by operator adjustment

NASA Technical Reports Server (NTRS)

Kruse, W.; Rothbauer, G.

1973-01-01

An optimal gain was established by measuring errors at 5 discrete control gain settings in an experimental set-up consisting of a 2-dimensional, first-order pursuit tracking task performed by subjects (S's). No significant experience effect on optimum gain setting was found in the first experiment. During the second experiment, in which control gain was continuously adjustable, high experienced S's tended to reach the previously determined optimum gain quite accurately and quickly. Less experienced S's tended to select a marginally optimum gain either below or above the experimentally determined optimum depending on initial control gain setting, although mean settings of both groups were equal. This quick and simple method is recommended for selecting control gains for different control systems and forcing functions.

Microbial whole‐cell arrays

PubMed Central

Elad, Tal; Lee, Jin Hyung; Belkin, Shimshon; Gu, Man Bock

2008-01-01

Summary The coming of age of whole‐cell biosensors, combined with the continuing advances in array technologies, has prepared the ground for the next step in the evolution of both disciplines – the whole‐cell array. In the present review, we highlight the state‐of‐the‐art in the different disciplines essential for a functional bacterial array. These include the genetic engineering of the biological components, their immobilization in different polymers, technologies for live cell deposition and patterning on different types of solid surfaces, and cellular viability maintenance. Also reviewed are the types of signals emitted by the reporter cell arrays, some of the transduction methodologies for reading these signals and the mathematical approaches proposed for their analysis. Finally, we review some of the potential applications for bacterial cell arrays, and list the future needs for their maturation: a richer arsenal of high‐performance reporter strains, better methodologies for their incorporation into hardware platforms, design of appropriate detection circuits, the continuing development of dedicated algorithms for multiplex signal analysis and – most importantly – enhanced long‐term maintenance of viability and activity on the fabricated biochips. PMID:21261831

In situ synthesis of protein arrays.

PubMed

He, Mingyue; Stoevesandt, Oda; Taussig, Michael J

2008-02-01

In situ or on-chip protein array methods use cell free expression systems to produce proteins directly onto an immobilising surface from co-distributed or pre-arrayed DNA or RNA, enabling protein arrays to be created on demand. These methods address three issues in protein array technology: (i) efficient protein expression and availability, (ii) functional protein immobilisation and purification in a single step and (iii) protein on-chip stability over time. By simultaneously expressing and immobilising many proteins in parallel on the chip surface, the laborious and often costly processes of DNA cloning, expression and separate protein purification are avoided. Recently employed methods reviewed are PISA (protein in situ array) and NAPPA (nucleic acid programmable protein array) from DNA and puromycin-mediated immobilisation from mRNA.

Replica amplification of nucleic acid arrays

DOEpatents

Church, George M.

2002-01-01

A method of producing a plurality of a nucleic acid array, comprising, in order, the steps of amplifying in situ nucleic acid molecules of a first randomly-patterned, immobilized nucleic acid array comprising a heterogeneous pool of nucleic acid molecules affixed to a support, transferring at least a subset of the nucleic acid molecules produced by such amplifying to a second support, and affixing the subset so transferred to the second support to form a second randomly-patterned, immobilized nucleic acid array, wherein the nucleic acid molecules of the second array occupy positions that correspond to those of the nucleic acid molecules from which they were amplified on the first array, so that the first array serves as a template to produce a plurality, is disclosed.

Flexible retinal electrode array

DOEpatents

Okandan, Murat [Albuquerque, NM; Wessendorf, Kurt O [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

2006-10-24

An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

Ga:Ge array development

NASA Technical Reports Server (NTRS)

Young, Erick T.; Rieke, G. H.; Low, Frank J.; Haller, E. E.; Beeman, J. W.

1989-01-01

Work at the University of Arizona and at Lawrence Berkeley Laboratory on the development of a far infrared array camera for the Multiband Imaging Photometer on the Space Infrared Telescope Facility (SIRTF) is discussed. The camera design uses stacked linear arrays of Ge:Ga photoconductors to make a full two-dimensional array. Initial results from a 1 x 16 array using a thermally isolated J-FET readout are presented. Dark currents below 300 electrons s(exp -1) and readout noises of 60 electrons were attained. Operation of these types of detectors in an ionizing radiation environment are discussed. Results of radiation testing using both low energy gamma rays and protons are given. Work on advanced C-MOS cascode readouts that promise lower temperature operation and higher levels of performance than the current J-FET based devices is described.

Preliminary results with microchannel array plates employing curved microchannels to inhibit ion feedback. [for photon counters

NASA Technical Reports Server (NTRS)

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

1977-01-01

Up to now, microchannel array plates (MCPs) have been constructed with microchannels having a straight geometry and hence have been prone to ion-feedback instabilities at high operating potentials and high ambient pressures. This paper describes the performances of MCPs with curved (J and C configuration) microchannels to inhibit ion feedback. Plates with curved microchannels have demonstrated performances comparable to those of conventional channel electron multipliers with saturated output pulse-height distributions and modal gain values in excess of 10 to the 6th electrons/pulse.

Optical antenna gain. I - Transmitting antennas

NASA Technical Reports Server (NTRS)

Klein, B. J.; Degnan, J. J.

1974-01-01

The gain of centrally obscured optical transmitting antennas is analyzed in detail. The calculations, resulting in near- and far-field antenna gain patterns, assume a circular antenna illuminated by a laser operating in the TEM-00 mode. A simple polynomial equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn that display the losses in antenna gain due to pointing errors and the cone angle of the beam in the far field as a function of antenna aperture size and its central obscuration. The results are presented in a series of graphs that allow the rapid and accurate evaluation of the antenna gain which may then be substituted into the conventional range equation.

Modeling Array Stations in SIG-VISA

NASA Astrophysics Data System (ADS)

Ding, N.; Moore, D.; Russell, S.

2013-12-01

We add support for array stations to SIG-VISA, a system for nuclear monitoring using probabilistic inference on seismic signals. Array stations comprise a large portion of the IMS network; they can provide increased sensitivity and more accurate directional information compared to single-component stations. Our existing model assumed that signals were independent at each station, which is false when lots of stations are close together, as in an array. The new model removes that assumption by jointly modeling signals across array elements. This is done by extending our existing Gaussian process (GP) regression models, also known as kriging, from a 3-dimensional single-component space of events to a 6-dimensional space of station-event pairs. For each array and each event attribute (including coda decay, coda height, amplitude transfer and travel time), we model the joint distribution across array elements using a Gaussian process that learns the correlation lengthscale across the array, thereby incorporating information of array stations into the probabilistic inference framework. To evaluate the effectiveness of our model, we perform ';probabilistic beamforming' on new events using our GP model, i.e., we compute the event azimuth having highest posterior probability under the model, conditioned on the signals at array elements. We compare the results from our probabilistic inference model to the beamforming currently performed by IMS station processing.

Pyroelectric detector arrays

NASA Technical Reports Server (NTRS)

Fripp, A. L.; Robertson, J. B.; Breckenridge, R. A. (Inventor)

1982-01-01

A pryoelectric detector array and the method for making it are described. A series of holes formed through a silicon dioxide layer on the surface of a silicon substrate forms the mounting fixture for the pyroelectric detector array. A series of nontouching strips of indium are formed around the holes to make contact with the backside electrodes and form the output terminals for individual detectors. A pyroelectric detector strip with front and back electrodes, respectively, is mounted over the strip. Biasing resistors are formed on the surface of the silicon dioxide layer and connected to the strips. A metallized pad formed on the surface of the layer is connected to each of the biasing resistors and to the film to provide the ground for the pyroelectric detector array.

MUSIC: An 8 channel readout ASIC for SiPM arrays

NASA Astrophysics Data System (ADS)

Gómez, Sergio; Gascón, David; Fernández, Gerard; Sanuy, Andreu; Mauricio, Joan; Graciani, Ricardo; Sanchez, David

2016-04-01

This paper presents an 8 channel ASIC for SiPM anode readout based on a novel low input impedance current conveyor (under patent1). This Multiple Use SiPM Integrated Circuit (MUSIC) has been designed to serve several purposes, including, for instance, the readout of SiPM arrays for some of the Cherenkov Telescope Array (CTA) cameras. The current division scheme at the very front end part of the circuit splits the input current into differently scaled copies which are connected to independent current mirrors. The circuit contains a tunable pole zero cancellation of the SiPM recovery time constant to deal with sensors from different manufacturers. Decay times up to 100 ns are supported covering most of the available SiPM devices in the market. MUSIC offers three main features: (1) differential output of the sum of the individual input channels; (2) 8 individual single ended analog outputs and; (3) 8 individual binary outputs. The digital outputs encode the amount of collected charge in the duration of the digital signal using a time over threshold technique. For each individual channel, the user must select the analog or digital output. Each functionality, the signal sum and the 8 A/D outputs, include a selectable dual-gain configuration. Moreover, the signal sum implements dual-gain output providing a 15 bit dynamic range. Full die simulation results of the MUSIC designed using AMS 0.35 µm SiGe technology are presented: total die size of 9 mm2, 500 MHz bandwidth for channel sum and 150 MHz bandwidth for A/D channels, low input impedance (≍32 Ω), single photon output pulse width at half maximum (FWHM) between 5 and 10 ns and with a power consumption of ≍ 30 mW/ch plus ≍ 200 mW for the 8 ch sum. Encapsulated prototype samples of the MUSIC are expected by March 2016.

Infrared-Bolometer Arrays with Reflective Backshorts

NASA Technical Reports Server (NTRS)

Miller, Timothy M.; Abrahams, John; Allen, Christine A.

2011-01-01

Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to

CMOS gate array characterization procedures

NASA Astrophysics Data System (ADS)

Spratt, James P.

1993-09-01

Present procedures are inadequate for characterizing the radiation hardness of gate array product lines prior to personalization because the selection of circuits to be used, from among all those available in the manufacturer's circuit library, is usually uncontrolled. (Some circuits are fundamentally more radiation resistant than others.) In such cases, differences in hardness can result between different designs of the same logic function. Hardness also varies because many gate arrays feature large custom-designed megacells (e.g., microprocessors and random access memories-MicroP's and RAM's). As a result, different product lines cannot be compared equally. A characterization strategy is needed, along with standardized test vehicle(s), methodology, and conditions, so that users can make informed judgments on which gate arrays are best suited for their needs. The program described developed preferred procedures for the radiation characterization of gate arrays, including a gate array evaluation test vehicle, featuring a canary circuit, designed to define the speed versus hardness envelope of the gate array. A multiplier was chosen for this role, and a baseline multiplier architecture is suggested that could be incorporated into an existing standard evaluation circuit chip.

Wind loads on flat plate photovoltaic array fields

NASA Technical Reports Server (NTRS)

Miller, R. D.; Zimmerman, D. K.

1981-01-01

The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

The ASTRI mini-array software system (MASS) implementation: a proposal for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Tanci, Claudio; Tosti, Gino; Conforti, Vito; Schwarz, Joseph; Antolini, Elisa; Antonelli, L. A.; Bulgarelli, Andrea; Bigongiari, Ciro; Bruno, Pietro; Canestrari, Rodolfo; Capalbi, Milvia; Cascone, Enrico; Catalano, Osvaldo; Di Paola, Andrea; Di Pierro, Federico; Fioretti, Valentina; Gallozzi, Stefano; Gardiol, Daniele; Gianotti, Fulvio; Giro, Enrico; Grillo, Alessandro; La Palombara, Nicola; Leto, Giuseppe; Lombardi, Saverio; Maccarone, Maria C.; Pareschi, Giovanni; Russo, Federico; Sangiorgi, Pierluca; Scuderi, Salvo; Stringhetti, Luca; Testa, Vincenzo; Trifoglio, Massimo; Vercellone, Stefano; Zoli, Andrea

2016-08-01

The ASTRI mini-array, composed of nine small-size dual mirror (SST-2M) telescopes, has been proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA), as a set of preproduction units of the CTA observatory. The ASTRI mini-array is a collaborative and international effort carried out by Italy, Brazil and South Africa and led by the Italian National Institute of Astrophysics, INAF. We present the main features of the current implementation of the Mini-Array Software System (MASS) now in use for the activities of the ASTRI SST-2M telescope prototype located at the INAF observing station on Mt. Etna, Italy and the characteristics that make it a prototype for the CTA control software system. CTA Data Management (CTADATA) and CTA Array Control and Data Acquisition (CTA-ACTL) requirements and guidelines as well as the ASTRI use cases were considered in the MASS design, most of its features are derived from the Atacama Large Millimeter/sub-millimeter Array Control software. The MASS will provide a set of tools to manage all onsite operations of the ASTRI mini-array in order to perform the observations specified in the short term schedule (including monitoring and controlling all the hardware components of each telescope and calibration device), to analyze the acquired data online and to store/retrieve all the data products to/from the onsite repository.

PEP solar array definition study

NASA Technical Reports Server (NTRS)

1979-01-01

The conceptual design of a large, flexible, lightweight solar array is presented focusing on a solar array overview assessment, solar array blanket definition, structural-mechanical systems definition, and launch/reentry blanket protection features. The overview assessment includes a requirements and constraints review, the thermal environment assessment on the design selection, an evaluation of blanket integration sequence, a conceptual blanket/harness design, and a hot spot analysis considering the effects of shadowing and cell failures on overall array reliability. The solar array blanket definition includes the substrate design, hinge designs and blanket/harness flexibility assessment. The structural/mechanical systems definition includes an overall loads and deflection assessment, a frequency analysis of the deployed assembly, a components weights estimate, design of the blanket housing and tensioning mechanism. The launch/reentry blanket protection task includes assessment of solar cell/cover glass cushioning concepts during ascent and reentry flight condition.

On the (Frequency) Modulation of Coupled Oscillator Arrays in Phased Array Beam Control

NASA Technical Reports Server (NTRS)

Pogorzelski, R.; Acorn, J.; Zawadzki, M.

2000-01-01

It has been shown that arrays of voltage controlled oscillators coupled to nearest neighbors can be used to produce useful aperture phase distributions for phased array antennas. However, placing information of the transmitted signal requires that the oscillations be modulated.

Method to fabricate hollow microneedle arrays

DOEpatents

Kravitz, Stanley H [Placitas, NM; Ingersoll, David [Albuquerque, NM; Schmidt, Carrie [Los Lunas, NM; Flemming, Jeb [Albuquerque, NM

2006-11-07

An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

Nanoelectrode array for electrochemical analysis

DOEpatents

Yelton, William G [Sandia Park, NM; Siegal, Michael P [Albuquerque, NM

2009-12-01

A nanoelectrode array comprises a plurality of nanoelectrodes wherein the geometric dimensions of the electrode controls the electrochemical response, and the current density is independent of time. By combining a massive array of nanoelectrodes in parallel, the current signal can be amplified while still retaining the beneficial geometric advantages of nanoelectrodes. Such nanoelectrode arrays can be used in a sensor system for rapid, non-contaminating field analysis. For example, an array of suitably functionalized nanoelectrodes can be incorporated into a small, integrated sensor system that can identify many species rapidly and simultaneously under field conditions in high-resistivity water, without the need for chemical addition to increase conductivity.

Fiber Laser Arrays

DTIC Science & Technology

2006-05-03

AFRL-DE-PS- AFRL-DE-PS- TR-2006-1059 TR-2006-1059 FIBER LASER ARRAYS Thomas B. Simpson L-3 Communications-Jaycor 3394...LEANNE J HENRY, Lt Col, USAF L. BRUCE SIMPSON, SES Chief, High Power Solid State Laser Branch Director, Directed Energy Directorate...SUBTITLE Fiber Laser Arrays 5c. PROGRAM ELEMENT NUMBER 62605F 5d. PROJECT NUMBER 4866 5e. TASK NUMBER LR 6. AUTHOR(S) Thomas B. Simpson

A novel compensation method for the anode gain non-uniformity of multi-anode photomultiplier tubes

NASA Astrophysics Data System (ADS)

Lee, Chan Mi; Kwon, Sun Il; Ko, Guen Bae; Ito, Mikiko; Yoon, Hyun Suk; Lee, Dong Soo; Jong Hong, Seong; Lee, Jae Sung

2012-01-01