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Sample records for linear cell array

  1. Is cell migration or proliferation dominant in the formation of linear arrays of oligodendrocytes?

    PubMed

    Walsh, Darragh M; Röth, Philipp T; Holmes, William R; Landman, Kerry A; Merson, Tobias D; Hughes, Barry D

    2016-10-01

    Oligodendrocytes are the myelin-producing cells of the central nervous system that are responsible for electrically insulating axons to speed the propagation of electrical impulses. A striking feature of oligodendrocyte development within white matter is that the cell bodies of many oligodendrocyte progenitor cells become organised into discrete linear arrays of three or more cells before they differentiate into myelin-producing oligodendrocytes. These linear arrays align parallel to the direction of the axons within white matter tracts and are believed to play an important role in the co-ordination of myelination. Guided by experimental data on the abundance and composition of linear arrays in the corpus callosum of the postnatal mouse brain, we construct discrete and continuous models of linear array generation to specifically investigate the relative influence of cell migration, proliferation, differentiation and death of oligodendroglia upon the genesis of linear arrays during early postnatal development. We demonstrate that only models that incorporate significant cell migration can replicate all of the experimental observations on number of arrays, number of cells in arrays and total cell count of oligodendroglia within a given area of the corpus callosum. These models are also necessary to accurately reflect experimental data on the abundance of linear arrays composed of oligodendrocytes that derive from progenitors of different clonal origins. PMID:27343034

  2. Designing linear systolic arrays

    SciTech Connect

    Kumar, V.K.P.; Tsai, Y.C. . Dept. of Electrical Engineering)

    1989-12-01

    The authors develop a simple mapping technique to design linear systolic arrays. The basic idea of the technique is to map the computations of a certain class of two-dimensional systolic arrays onto one-dimensional arrays. Using this technique, systolic algorithms are derived for problems such as matrix multiplication and transitive closure on linearly connected arrays of PEs with constant I/O bandwidth. Compared to known designs in the literature, the technique leads to modular systolic arrays with constant hardware in each PE, few control lines, lexicographic data input/output, and improved delay time. The unidirectional flow of control and data in this design assures implementation of the linear array in the known fault models of wafer scale integration.

  3. Optical Scanner for Linear Arrays

    NASA Technical Reports Server (NTRS)

    Finkel, M. W.

    1986-01-01

    Optical scanner instantaneously reads contiguous lines forming scene or target in object plane. Reading active or passive and scans, continuous or discrete. Scans essentially linear with scan angle and symmetric about axial ray. Nominal focal error, resulting from curvature of scan, well within Rayleigh limit. Scanner specifically designed to be fully compatible with general requirements of linear arrays.

  4. A new method of linear control for optimum transfer of power from a solar cell array to the distribution network

    NASA Astrophysics Data System (ADS)

    Ray, G. C.; Jha, R.

    1984-08-01

    The paper describes a new method of linear control for transfer of optimum power from a Solar Cell Array (SCA) to the distribution network. It is shown that the current corresponding to the optimum power varies almost linearly with the level of illumination. By connecting a storage battery in parallel to the SCA, the charging current to the battery is continuously adjusted by sensing the ilumination level and current simultaneously. Variation of the charging current keeps the operating point on the optimum power locus. In the ac distribution network the power is to be fed through a current-source inverter and a step up/down transformer.

  5. Linear array optical edge sensor

    NASA Technical Reports Server (NTRS)

    Bejczy, Antal K. (Inventor); Primus, Howard C. (Inventor)

    1987-01-01

    A series of independent parallel pairs of light emitting and detecting diodes for a linear pixel array, which is laterally positioned over an edge-like discontinuity in a workpiece to be scanned, is disclosed. These independent pairs of light emitters and detectors sense along intersecting pairs of separate optical axes. A discontinuity, such as an edge in the sensed workpiece, reflects a detectable difference in the amount of light from that discontinuity in comparison to the amount of light that is reflected on either side of the discontinuity. A sequentially sychronized clamping and sampling circuit detects that difference as an electrical signal which is recovered by circuitry that exhibits an improved signal-to-noise capability for the system.

  6. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  7. Multispectral linear array multiband selection device

    NASA Technical Reports Server (NTRS)

    Richard, H. L.

    1986-01-01

    An apparatus for detecting multiple spectral bands, individually or concurrently, using linear detector arrays is described. The system employs a beamsplitter to divide the optical source into two or more optical beams which are directed at the linear detector arrays. Filter trays are positioned in the focal planes of the optical beams so that the beams pass through the filter trays prior to impinging upon the detector arrays. Multiple filters are placed on the filter trays. Linear actuators positioned adjacent the filter trays translate the trays across the focal planes of the optical beams so that individual filters are positioned in the path of beams such that those frequencies of the beams that fall within the spectral ranges of the individual bandpass filter through which it passes may be detected by the detector arrays for further examination and analysis.

  8. Fast time-domain modeling of fluid-coupled cMUT cells: from the single cell to the 1-D linear array element.

    PubMed

    Sénégond, Nicolas; Boulmé, Audren; Plag, Camille; Teston, Franck; Certon, Dominique

    2013-07-01

    We report a fast time-domain model of fluid-coupled cMUTs developed to predict the transient response-i.e., the impulse pressure response--of an element of a linear 1-D array. Mechanical equations of the cMUT diaphragm are solved with 2-D finite-difference schemes. The time-domain solving method is a fourth--order Runge-Kutta algorithm. The model takes into account the electrostatic nonlinearity and the contact with the bottom electrode when the membrane is collapsed. Mutual acoustic coupling between cells is introduced through the numerical implementation of analytical solutions of the impulse diffraction theory established in the case of acoustic sources with rectangular geometry. Processing times are very short: they vary from a few minutes for a single cell to a maximum of 30 min for one element of an array. After a description of the model, the impact of the nonlinearity and the pull-in/pull-out phenomena on the dynamic behavior of the cMUT diaphragm is discussed. Experimental results of mechanical displacements obtained by interferometric measurements and the acoustic pressure field are compared with simulations. Different excitation signals-high-frequency bandwidth pulses and toneburst excitations of varying central frequency-were chosen to compare theory with experimental results. PMID:25004518

  9. Pyroelectric infrared linear arrays based on PIMNT

    NASA Astrophysics Data System (ADS)

    Ma, Xueliang; Shao, Xiumei; Yu, Yuehua; Luo, Haosu; Liu, Linhua; Xia, Wang; Li, Yanjin

    2012-10-01

    Pyroelectric infrared linear arrays can work at ambient temperature without cryogenic system and have the merits of comparatively homogenous spectral response in wide spectrum range, compact structure, long-time stability and low cost for many applications. xPb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-(1-x-y)PbTiO3 (PIMNT) single crystal is a kind of novel pyroelectric material, which possesses superior pyroelectric performances and is appraised as a candidate for high performance pyroelectric infrared linear arrays. This paper describes the layout and essential properties of the pyroelectric infrared linear arrays based on PIMNT with 128 responsive elements. The transmittance measurement of PIMNT indicates that an absorption layer is needed when the PIMNT based linear arrays work at room temperature in 0.8 - 12.0 μm wave range due to the low absorption ratio especially in 0.8 - 10.0 μm wave band. The arrays employ a hybrid structure consisting of the PIMNT pyroelectric chip and CMOS read-out circuit. They are electrically bonded by ultrasonic bonding process. Also some details of the process technologies of the PIMNT pyroelectric chip are depicted in this paper.

  10. Some results concerning linear iterative (systolic) arrays

    SciTech Connect

    Ibarra, O.H.; Palis, M.A.; Kim, S.M.

    1985-05-01

    The authors have shown some new interesting results concerning the properties, power, and limitations of various types of linear iterative (systolic) arrays. The method they employed consisted of finding sequential machine characterizations of these array models, and then using the characterizations to prove the results. Because of the absence of any concurrency and synchronization problems, the authors obtained simple proofs to results which when proved directly on the arrays would seem very difficult. The characterizations, therefore, provide a novel and promising method which can be used to analyze other systolic systems. In the future they hope to extend this methodology to the study of two-dimensional and multidimensional systolic arrays, and other systolic systems with different interconnection networks.

  11. Linear Microbolometric Array Based on VOx Thin Film

    NASA Astrophysics Data System (ADS)

    Chen, Xi-Qu

    2010-05-01

    In this paper, a linear microbolometric array based on VOx thin film is proposed. The linear microbolometric array is fabricated by using micromachining technology, and its thermo-sensitive VOx thin film has excellent infrared response spectrum and TCR characteristics. Integrated with CMOS circuit, an experimentally prototypical monolithic linear microbolometric array is designed and fabricated. The testing results of the experimental linear array show that the responsivity of linear array can approach 18KV/W and is potential for infrared image systems.

  12. Microbial sensor cell arrays.

    PubMed

    Melamed, Sahar; Elad, Tal; Belkin, Shimshon

    2012-02-01

    Motivated by the advantages endowed by high-throughput analysis, researchers have succeeded in incorporating multiple reporter cells into a single platform; the technology now allows the simultaneous scrutiny of a large collection of sensor strains. We review current aspects in cell array technology with emphasis on microbial sensor arrays. We consider various techniques for patterning live cells on solid surfaces, describe different array-based applications and devices, and highlight recent efforts for live cell storage. We review mathematical approaches for deciphering the data emanating from bioreporter collections, and discuss the future of single cell arrays. Innovative technologies for cell patterning, preservation and interpretation are continuously being developed; when they all mature, cell arrays may become an efficient analytical tool, in a scope resembling that of DNA microarray biochips. PMID:22176747

  13. Linear-array systems for aerospace NDE

    NASA Astrophysics Data System (ADS)

    Smith, Robert A.; Willsher, Stephen J.; Bending, Jamie M.

    1999-12-01

    Rapid large-area inspection of composite structures for impact damage and multi-layered aluminum skins for corrosion has been a recognized priority for several years in both military and civil aerospace applications. Approaches to this requirement have followed two clearly different routes: the development of novel large-area inspection systems, and the enhancement of current ultrasonic or eddy-current methods to reduce inspection times. Ultrasonic inspection is possible with standard flaw detection equipment but the addition of a linear ultrasonic array could reduce inspection times considerably. In order to investigate their potential, 9-element and 17-element linear ultrasonic arrays for composites, and 64-element arrays for aluminum skins, have been developed to DERA specifications for use with the ANDSCAN® area scanning system. A 5 m2 composite wing surface has been scanned with a scan resolution of approximately 3 mm in 6 hours. With subsequent software and hardware improvements all four composite wing surfaces (top/bottom, left/right) of a military fighter aircraft can potentially be inspected in less than a day. Array technology has been very widely used in the medical ultrasound field although rarely above 10 MHz, whereas lap-joint inspection requires a pulse center-frequency of 12 to 20 MHz in order to resolve the separate interfaces in the lap joint. A 128 mm-long multi-element array of 5 mm×2 mm ultrasonic elements for use with the ANDSCAN® scanning software was produced to a DERA specification by an NDT manufacturer with experience in the medical imaging field. This paper analyses the performance of the transducers that have been produced and evaluates their use in scanning systems of different configurations.

  14. Linear-array systems for aerospace NDE

    SciTech Connect

    Smith, Robert A.; Willsher, Stephen J.; Bending, Jamie M.

    1999-12-02

    Rapid large-area inspection of composite structures for impact damage and multi-layered aluminum skins for corrosion has been a recognized priority for several years in both military and civil aerospace applications. Approaches to this requirement have followed two clearly different routes: the development of novel large-area inspection systems, and the enhancement of current ultrasonic or eddy-current methods to reduce inspection times. Ultrasonic inspection is possible with standard flaw detection equipment but the addition of a linear ultrasonic array could reduce inspection times considerably. In order to investigate their potential, 9-element and 17-element linear ultrasonic arrays for composites, and 64-element arrays for aluminum skins, have been developed to DERA specifications for use with the ANDSCAN area scanning system. A 5 m{sup 2} composite wing surface has been scanned with a scan resolution of approximately 3 mm in 6 hours. With subsequent software and hardware improvements all four composite wing surfaces (top/bottom, left/right) of a military fighter aircraft can potentially be inspected in less than a day. Array technology has been very widely used in the medical ultrasound field although rarely above 10 MHz, whereas lap-joint inspection requires a pulse center-frequency of 12 to 20 MHz in order to resolve the separate interfaces in the lap joint. A 128 mm-long multi-element array of 5 mmx2 mm ultrasonic elements for use with the ANDSCAN scanning software was produced to a DERA specification by an NDT manufacturer with experience in the medical imaging field. This paper analyses the performance of the transducers that have been produced and evaluates their use in scanning systems of different configurations.

  15. Stripe filters on multispectral linear arrays

    NASA Technical Reports Server (NTRS)

    Hall, J. H.; Blaha, F. C.; Frias, B. R.; Halvis, J.; Hubbard, E.

    1982-01-01

    Dielectric interference filters deposited directly on top of existing 200 element charge coupled device linear imaging arrays were designed, fabricated and evaluated. The optical performance of the filters was verified with regard to crosstalk between adjacent detector elements. The filters showed an average in-band transmittance greater than 80% and a total out of band transmittance of less than 5%. Filter stability was adequate for operation in a space environment. The filter elements were definable in 12 to 25 micron element size compatible with existing silicon detectors. These type of measurement were made: (1) spectral transmission of the filter as deposited on witness plates; (2) spectral response of the silicon sensing device; (3) any optical interaction between filter and sensing device; (4) the response of the filter/sensor combination; and (5) repeatability and uniformity of filter characteristics. Detailed discussion of these evaluations are given.

  16. Linear-array ultrasonic waveguide transducer for under sodium viewing.

    SciTech Connect

    Sheen, S. H.; Chien, H. T.; Wang, K.; Lawrence, W. P.; Engel, D.; Nuclear Engineering Division

    2010-09-01

    In this report, we first present the basic design of a low-noise waveguide and its performance followed by a review of the array transducer technology. The report then presents the concept and basic designs of arrayed waveguide transducers that can apply to under-sodium viewing for in-service inspection of fast reactors. Depending on applications, the basic waveguide arrays consist of designs for sideway and downward viewing. For each viewing application, two array geometries, linear and circular, are included in design analysis. Methods to scan a 2-D target using a linear array waveguide transducer are discussed. Future plan to develop a laboratory array waveguide prototype is also presented.

  17. Photovoltaic cell array

    NASA Technical Reports Server (NTRS)

    Eliason, J. T. (Inventor)

    1976-01-01

    A photovoltaic cell array consisting of parallel columns of silicon filaments is described. Each fiber is doped to produce an inner region of one polarity type and an outer region of an opposite polarity type to thereby form a continuous radial semi conductor junction. Spaced rows of electrical contacts alternately connect to the inner and outer regions to provide a plurality of electrical outputs which may be combined in parallel or in series.

  18. Linearly tapered slot antenna circular array for mobile communications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  19. Underwater Imaging Using a 1 × 16 CMUT Linear Array.

    PubMed

    Zhang, Rui; Zhang, Wendong; He, Changde; Zhang, Yongmei; Song, Jinlong; Xue, Chenyang

    2016-01-01

    A 1 × 16 capacitive micro-machined ultrasonic transducer linear array was designed, fabricated, and tested for underwater imaging in the low frequency range. The linear array was fabricated using Si-SOI bonding techniques. Underwater transmission performance was tested in a water tank, and the array has a resonant frequency of 700 kHz, with pressure amplitude 182 dB (μPa·m/V) at 1 m. The -3 dB main beam width of the designed dense linear array is approximately 5 degrees. Synthetic aperture focusing technique was applied to improve the resolution of reconstructed images, with promising results. Thus, the proposed array was shown to be suitable for underwater imaging applications. PMID:26938536

  20. Underwater Imaging Using a 1 × 16 CMUT Linear Array

    PubMed Central

    Zhang, Rui; Zhang, Wendong; He, Changde; Zhang, Yongmei; Song, Jinlong; Xue, Chenyang

    2016-01-01

    A 1 × 16 capacitive micro-machined ultrasonic transducer linear array was designed, fabricated, and tested for underwater imaging in the low frequency range. The linear array was fabricated using Si-SOI bonding techniques. Underwater transmission performance was tested in a water tank, and the array has a resonant frequency of 700 kHz, with pressure amplitude 182 dB (μPa·m/V) at 1 m. The −3 dB main beam width of the designed dense linear array is approximately 5 degrees. Synthetic aperture focusing technique was applied to improve the resolution of reconstructed images, with promising results. Thus, the proposed array was shown to be suitable for underwater imaging applications. PMID:26938536

  1. High resolution 64-element pyroelectric linear array IR detector

    NASA Astrophysics Data System (ADS)

    Turnbull, Andrew A.; Cooke, Martin E.

    1987-01-01

    A 64-element pyroelectric linear array detector has been developed. Included within the detector is a corresponding array of source followers together with a multiplexer and amplifier. High responsivity and high detectivity have been achieved, together with a low level of microphony.

  2. Multispectral linear array (MLA) focal plane mechanical and thermal design

    NASA Technical Reports Server (NTRS)

    Mitchell, A. S.; Kaminski, E. F.

    1982-01-01

    The mechanical and thermal design of an integrated focal plane subsystem of a Multispectral Linear Array (MLA) instrument is discussed in terms of focal-plane alignment, thermoelastic performance, and thermal requirements. The modular construction and thermal control of the focal plane array are discussed.

  3. Jet Noise Source Localization Using Linear Phased Array

    NASA Technical Reports Server (NTRS)

    Agboola, Ferni A.; Bridges, James

    2004-01-01

    A study was conducted to further clarify the interpretation and application of linear phased array microphone results, for localizing aeroacoustics sources in aircraft exhaust jet. Two model engine nozzles were tested at varying power cycles with the array setup parallel to the jet axis. The array position was varied as well to determine best location for the array. The results showed that it is possible to resolve jet noise sources with bypass and other components separation. The results also showed that a focused near field image provides more realistic noise source localization at low to mid frequencies.

  4. Reconstruction Techniques for Sparse Multistatic Linear Array Microwave Imaging

    SciTech Connect

    Sheen, David M.; Hall, Thomas E.

    2014-06-09

    Sequentially-switched linear arrays are an enabling technology for a number of near-field microwave imaging applications. Electronically sequencing along the array axis followed by mechanical scanning along an orthogonal axis allows dense sampling of a two-dimensional aperture in near real-time. In this paper, a sparse multi-static array technique will be described along with associated Fourier-Transform-based and back-projection-based image reconstruction algorithms. Simulated and measured imaging results are presented that show the effectiveness of the sparse array technique along with the merits and weaknesses of each image reconstruction approach.

  5. Linear antenna array optimization using flower pollination algorithm.

    PubMed

    Saxena, Prerna; Kothari, Ashwin

    2016-01-01

    Flower pollination algorithm (FPA) is a new nature-inspired evolutionary algorithm used to solve multi-objective optimization problems. The aim of this paper is to introduce FPA to the electromagnetics and antenna community for the optimization of linear antenna arrays. FPA is applied for the first time to linear array so as to obtain optimized antenna positions in order to achieve an array pattern with minimum side lobe level along with placement of deep nulls in desired directions. Various design examples are presented that illustrate the use of FPA for linear antenna array optimization, and subsequently the results are validated by benchmarking along with results obtained using other state-of-the-art, nature-inspired evolutionary algorithms such as particle swarm optimization, ant colony optimization and cat swarm optimization. The results suggest that in most cases, FPA outperforms the other evolutionary algorithms and at times it yields a similar performance. PMID:27066339

  6. Reconstruction techniques for sparse multistatic linear array microwave imaging

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Hall, Thomas E.

    2014-06-01

    Sequentially-switched linear arrays are an enabling technology for a number of near-field microwave imaging applications. Electronically sequencing along the array axis followed by mechanical scanning along an orthogonal axis allows dense sampling of a two-dimensional aperture in near real-time. The Pacific Northwest National Laboratory (PNNL) has developed this technology for several applications including concealed weapon detection, groundpenetrating radar, and non-destructive inspection and evaluation. These techniques form three-dimensional images by scanning a diverging beam swept frequency transceiver over a two-dimensional aperture and mathematically focusing or reconstructing the data into three-dimensional images. Recently, a sparse multi-static array technology has been developed that reduces the number of antennas required to densely sample the linear array axis of the spatial aperture. This allows a significant reduction in cost and complexity of the linear-array-based imaging system. The sparse array has been specifically designed to be compatible with Fourier-Transform-based image reconstruction techniques; however, there are limitations to the use of these techniques, especially for extreme near-field operation. In the extreme near-field of the array, back-projection techniques have been developed that account for the exact location of each transmitter and receiver in the linear array and the 3-D image location. In this paper, the sparse array technique will be described along with associated Fourier-Transform-based and back-projection-based image reconstruction algorithms. Simulated imaging results are presented that show the effectiveness of the sparse array technique along with the merits and weaknesses of each image reconstruction approach.

  7. Clutter locus equation for more general linear array orientation

    NASA Astrophysics Data System (ADS)

    Bickel, Douglas L.

    2011-06-01

    The clutter locus is an important concept in space-time adaptive processing (STAP) for ground moving target indicator (GMTI) radar systems. The clutter locus defines the expected ground clutter location in the angle-Doppler domain. Typically in literature, the clutter locus is presented as a line, or even a set of ellipsoids, under certain assumptions about the geometry of the array. Most often, the array is assumed to be in the horizontal plane containing the velocity vector. This paper will give a more general 3-dimensional interpretation of the clutter locus for a general linear array orientation.

  8. Study of Far—Field Directivity Pattern for Linear Arrays

    NASA Astrophysics Data System (ADS)

    Ana-Maria, Chiselev; Luminita, Moraru; Laura, Onose

    2011-10-01

    A model to calculate directivity pattern in far field is developed in this paper. Based on this model, the three-dimensional beam pattern is introduced and analyzed in order to investigate geometric parameters of linear arrays and their influences on the directivity pattern. Simulations in azimuthal plane are made to highlight the influence of transducers parameters, including number of elements and inter-element spacing. It is true that these parameters are important factors that influence the directivity pattern and the appearance of side-lobes for linear arrays.

  9. Operation of linear and ring arrays in shallow water

    NASA Astrophysics Data System (ADS)

    Burdukovskaya, V. G.; Petukhov, Yu. V.; Khil'ko, A. I.

    2015-11-01

    With the aim of unambiguously determining the direction to a tonal emission source, comparative analysis of the directed properties of sufficiently extended linear and ring horizontal arrays in shallow water was performed. An isovelocity waveguide with a homogeneous fluid bottom was used as the shallow water model, in which a multimode regime of acoustic signal propagation was achieved.

  10. Position sensor for linear synchronous motors employing halbach arrays

    DOEpatents

    Post, Richard Freeman

    2014-12-23

    A position sensor suitable for use in linear synchronous motor (LSM) drive systems employing Halbach arrays to create their magnetic fields is described. The system has several advantages over previously employed ones, especially in its simplicity and its freedom from being affected by weather conditions, accumulated dirt, or electrical interference from the LSM system itself.

  11. Cold radiation shield design for a linear detector array. II

    NASA Astrophysics Data System (ADS)

    Dhar, Vikram; Gopal, Vishnu

    1986-11-01

    This communication reports the results of a calculation of cold-shield shading effects in the linear detector array described by Gopal and Dhar (1986), for an elliptical aperture geometry with varying major-to-minor axis ratio. The results suggest that an elliptical aperture geometry is a better design than a rectangular aperture.

  12. Spaceborne linear arrays of 512×3 microbolometers

    NASA Astrophysics Data System (ADS)

    Ngo Phong, Linh; Pancrati, Ovidiu; Marchese, Linda; Châteauneuf, François

    2013-03-01

    Details on the first linear arrays of 512×3 VOx microbolometers operating in space are reported. Arrays of this format are suited for remote sensing where relative motion between the spacecraft and target provides an inherent scanning mechanism. To take full advantage of the linear format, the array is built on a custom readout electronics that enables simultaneous integration of all pixels for scanning periods of up to 140 ms. The output signal from each pixel is digitized to 14 bits using a voltage-to-frequency conversion mechanism. Two arrays, integrated into two spectrally distinct radiometric packages, provide for coregistration of infrared images in three bands centered at 3.8, 10.85, and 11.85 μm for the retrieval of fire and sea surface temperatures. Analysis of the downlinked data confirms the reliable in-orbit operation and consistency with pre-launch characteristics for both arrays. Algorithms have been developed to perform post processing and absolute radiometric calibration of images in all bands. Image deconvolution using Wiener filtering was found effective in recovering the signal loss incurred in the active pixels when observing high temperature events. The in-flight gain and offset values were evaluated for all pixels by means of deep space measurements and cross calibration with reference spaceborne sensors. Preliminary assessment of the images calibrated using these values showed that they are in agreement with those retrieved from GOES sensor.

  13. Very High Frequency (Beyond 100 MHz) PZT Kerfless Linear Arrays

    PubMed Central

    Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-µm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-µm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss). PMID:19942516

  14. Solar cell array interconnects

    DOEpatents

    Carey, P.G.; Thompson, J.B.; Colella, N.J.; Williams, K.A.

    1995-11-14

    Electrical interconnects are disclosed for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value. 4 figs.

  15. Solar cell array interconnects

    DOEpatents

    Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

    1995-01-01

    Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

  16. Linear laser diode arrays for improvement in optical disk recording

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  17. Linear micromechanical stepping drive for pinhole array positioning

    NASA Astrophysics Data System (ADS)

    Endrödy, Csaba; Mehner, Hannes; Grewe, Adrian; Hoffmann, Martin

    2015-05-01

    A compact linear micromechanical stepping drive for positioning a 7 × 5.5 mm2 optical pinhole array is presented. The system features a step size of 13.2 µm and a full displacement range of 200 µm. The electrostatic inch-worm stepping mechanism shows a compact design capable of positioning a payload 50% of its own weight. The stepping drive movement, step sizes and position accuracy are characterized. The actuated pinhole array is integrated in a confocal chromatic hyperspectral imaging system, where coverage of the object plane, and therefore the useful picture data, can be multiplied by 14 in contrast to a non-actuated array.

  18. Linear array for covariance differencing via hyperbolic singular value decomposition

    NASA Astrophysics Data System (ADS)

    Bojanczyk, A. W.; Steinhardt, A. O.

    1989-11-01

    We consider a problem pertaining to bearing estimation in unknown noise using the covariance differencing approach, and propose a linear array of processors which exhibits a linear speed-up with respect to a uniprocessor system. Our solution hinges on a new canonic matrix factorization which we term the hyperbolic singular value decomposition. The parallel algorithm for hyperbolic SVD based bearing estimation is an adaptation of a well known biorthogonalization technique developed by Hestenes. Parallel implementations of the algorithm are based on earlier works on one-sided Jacobi methods. It turns out that strategies for parallelization of Jacobi methods are equally well applicable for computing the hyperbolic singular value decomposition.

  19. Double interconnection fuel cell array

    DOEpatents

    Draper, Robert; Zymboly, Gregory E.

    1993-01-01

    A fuel cell array (10) is made, containing number of tubular, elongated fuel cells (12) which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes (14) and outer electrodes (18 and 18'), with solid electrolyte (16 and 16') between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections (20 and 20') contacting the inner electrode (14), each cell (12) having only three metallic felt electrical connectors (22) which contact surrounding cells, where each row is electrically connected to the other.

  20. Template Synthesis of Carbon Nanofibers Containing Linear Mesocage Arrays

    PubMed Central

    2010-01-01

    Carbon nanofibers containing linear mesocage arrays were prepared via evaporation induced self-assembly method within AAO template with an average channel diameter of about 25 nm. The TEM results show that the mesocages have an elongated shape in the transversal direction. The results of N2 adsorption–desorption analysis indicate that the sample possesses a cage-like mesoporous structure and the average mesopore size of the sample is about 18 nm. PMID:20671793

  1. Photoelectric solar cell array

    SciTech Connect

    Lidorenko, N.S.; Afian, V.V.; Martirosian, R.G.; Ryabikov, S.V.; Strebkov, D.S.; Vartanian, A.V.

    1983-11-29

    A photoelectric solar cell device comprises a dispersing element exposed to the sun's radiation and followed in the optical path by photocells having different spectral sensitivities. Each photocell has its working surface so oriented that the light beam with the wavelength corresponding to the maximum spectral sensitivity of that photocell impinges on its working surface. The dispersing element is a hologram representing light sources with different wavelengths. The photocells are positioned in the image planes of the light sources producing the light beams of the corresponding wavelengths.

  2. Spatial Signature Estimation with an Uncalibrated Uniform Linear Array

    PubMed Central

    Cao, Xiang; Xin, Jingmin; Nishio, Yoshifumi; Zheng, Nanning

    2015-01-01

    In this paper, the problem of spatial signature estimation using a uniform linear array (ULA) with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs) can only be determined within an unknown rotational angle in this array model. However, the phase ambiguity has no impact on the identification of the spatial signature. Two auto-calibration methods are presented for spatial signature estimation. In our methods, the rotational DOAs and model error parameters are firstly obtained, and the spatial signature is subsequently calculated. The first method extracts two subarrays from the ULA to construct an estimator, and the elements of the array can be used several times in one subarray. The other fully exploits multiple invariances in the interior of the sensor array, and a multidimensional nonlinear problem is formulated. A Gauss–Newton iterative algorithm is applied for solving it. The first method can provide excellent initial inputs for the second one. The effectiveness of the proposed algorithms is demonstrated by several simulation results. PMID:26076405

  3. Spatial Signature Estimation with an Uncalibrated Uniform Linear Array.

    PubMed

    Cao, Xiang; Xin, Jingmin; Nishio, Yoshifumi; Zheng, Nanning

    2015-01-01

    In this paper, the problem of spatial signature estimation using a uniform linear array (ULA) with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs) can only be determined within an unknown rotational angle in this array model. However, the phase ambiguity has no impact on the identification of the spatial signature. Two auto-calibration methods are presented for spatial signature estimation. In our methods, the rotational DOAs and model error parameters are firstly obtained, and the spatial signature is subsequently calculated. The first method extracts two subarrays from the ULA to construct an estimator, and the elements of the array can be used several times in one subarray. The other fully exploits multiple invariances in the interior of the sensor array, and a multidimensional nonlinear problem is formulated. A Gauss-Newton iterative algorithm is applied for solving it. The first method can provide excellent initial inputs for the second one. The effectiveness of the proposed algorithms is demonstrated by several simulation results. PMID:26076405

  4. Automated control of linear constricted plasma source array

    DOEpatents

    Anders, Andre; Maschwitz, Peter A.

    2000-01-01

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

  5. Spatial frequency multiplier with active linearly tapered slot antenna array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1994-01-01

    A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques.

  6. 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.

  7. Wake Vortex Detection: Phased Microphone vs. Linear Infrasonic Array

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Zuckerwar, Allan J.; Sullivan, Nicholas T.; Knight, Howard K.

    2014-01-01

    infrasonic array at the Newport News-Williamsburg International Airport early in the year 2013. A pattern of pressure burst, high-coherence intervals, and diminishing-coherence intervals was observed for all takeoff and landing events without exception. The results of a phased microphone vs. linear infrasonic array comparison will be presented.

  8. A simplified solar cell array modelling program

    NASA Technical Reports Server (NTRS)

    Hughes, R. D.

    1982-01-01

    As part of the energy conversion/self sufficiency efforts of DSN engineering, it was necessary to have a simplified computer model of a solar photovoltaic (PV) system. This article describes the analysis and simplifications employed in the development of a PV cell array computer model. The analysis of the incident solar radiation, steady state cell temperature and the current-voltage characteristics of a cell array are discussed. A sample cell array was modelled and the results are presented.

  9. Infrared speckle interferometer with a linear array detector

    NASA Astrophysics Data System (ADS)

    Kataza, Hirokazu; Maihara, Toshinori

    1993-04-01

    We have developed a 1D near-IR speckle interferometer with a linear-array detector which can produce speckle images by means of a cylindrical lens. The detector with a Reticon multiplexer is operated at the kTC noise limit (approximately 2500 e-, rms). Using this instrument, we have obtained systematic data of the exposure time dependence of the modulation transfer function along with astronomical observations. The result indicates that the best exposure time of the speckle interferometry is longer than the exposure time chosen so that the fluctuations in the atmosphere are approximately frozen within an exposure. In the actual observations at the University of Hawaii 2.2-m telescope at Mauna Kea, the optimum exposure time is proved to be about 0.3 s.

  10. Thermal crosstalk simulation and measurement of linear terahertz detector arrays

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Huang, Zehua; Wang, Jun; Li, Mingyu; Gou, Jun; Jiang, Yadong

    2015-11-01

    Thermal simulation of differently structured linear terahertz detector arrays (TDAs) based on lithium tantalate was performed by finite element analysis (FEA). Simulation results revealed that a relatively simple TDA structure can have good thermal insulation, i.e., low thermal crosstalk effect (TCE), between adjacent pixels, which was thus selected for the real fabrication of TDA sample. Current responsivity (Ri) of the sample for a 2.52 THz source was measured to be 6.66 × 10-6 A/W and non-uniformity (NU) of Ri was 4.1%, showing good performance of the sample. TCE test result demonstrated that small TCE existed in the sample, which was in good agreement with the simulation results.

  11. Simplified System Efficiency Functions for Linear Phased-Array Transducers

    NASA Astrophysics Data System (ADS)

    Margetan, F. J.; Gray, T. A.; Huang, Ruiju

    2010-02-01

    Computer models are often used to simulate ultrasonic inspections of industrial components. One ingredient of such simulations is a frequency dependent function which describes the efficiency of the inspection system for converting electrical energy to sound and vice versa. For a phased-array transducer there are many such efficiency functions, namely one for each independent pair of piezoelectric elements. In this paper we describe a simplified, approximate approach for specifying these functions. Element-to-element differences are accounted for by two "residual" parameters: (1) a strength factor which describes the relative "hotness" of an element compared to its peers; and (2) a time delay which describes the extent to which an element fires later or earlier than its peers when all elements are instructed to fire in unison. These residuals are used to relate the system efficiency function for any pair of elements to that of an average efficiency which can be readily measured. The use of this approach is demonstrated using front-wall and back-wall responses from a stainless steel block, as acquired using a 5-MHz, 32-element, linear phased-array transducer. Good agreement was found between measured and simulated surface responses.

  12. Fast 2D DOA Estimation Algorithm by an Array Manifold Matching Method with Parallel Linear Arrays.

    PubMed

    Yang, Lisheng; Liu, Sheng; Li, Dong; Jiang, Qingping; Cao, Hailin

    2016-01-01

    In this paper, the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation with parallel linear arrays is addressed. Two array manifold matching (AMM) approaches, in this work, are developed for the incoherent and coherent signals, respectively. The proposed AMM methods estimate the azimuth angle only with the assumption that the elevation angles are known or estimated. The proposed methods are time efficient since they do not require eigenvalue decomposition (EVD) or peak searching. In addition, the complexity analysis shows the proposed AMM approaches have lower computational complexity than many current state-of-the-art algorithms. The estimated azimuth angles produced by the AMM approaches are automatically paired with the elevation angles. More importantly, for estimating the azimuth angles of coherent signals, the aperture loss issue is avoided since a decorrelation procedure is not required for the proposed AMM method. Numerical studies demonstrate the effectiveness of the proposed approaches. PMID:26907301

  13. Fast 2D DOA Estimation Algorithm by an Array Manifold Matching Method with Parallel Linear Arrays

    PubMed Central

    Yang, Lisheng; Liu, Sheng; Li, Dong; Jiang, Qingping; Cao, Hailin

    2016-01-01

    In this paper, the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation with parallel linear arrays is addressed. Two array manifold matching (AMM) approaches, in this work, are developed for the incoherent and coherent signals, respectively. The proposed AMM methods estimate the azimuth angle only with the assumption that the elevation angles are known or estimated. The proposed methods are time efficient since they do not require eigenvalue decomposition (EVD) or peak searching. In addition, the complexity analysis shows the proposed AMM approaches have lower computational complexity than many current state-of-the-art algorithms. The estimated azimuth angles produced by the AMM approaches are automatically paired with the elevation angles. More importantly, for estimating the azimuth angles of coherent signals, the aperture loss issue is avoided since a decorrelation procedure is not required for the proposed AMM method. Numerical studies demonstrate the effectiveness of the proposed approaches. PMID:26907301

  14. Array representation of nonidentical electrical cells

    NASA Astrophysics Data System (ADS)

    Appelbaum, J.; Shechter, M.; Yekutieli, G.; Bany, J.

    1982-08-01

    Electrical cells (electrochemical cells, fuel cells, solar cells) are of relatively low voltage and power levels. The cells are, therefore, connected in series and parallel combinations to form an array that produces the desired voltage and power. The cells are 'non-identical' in their parameter values and have a certain statistical distribution. The dispersion of the cell parameters affects the electrical behavior of the array in such a way that the power output of the array may differ from the power output of the individual cells operating separately at the same conditions. This difference depends on the cell type, cell parameter distribution, array configuration, and the load type. The paper introduces a general procedure for the determination of the array performance of nonidentical cells based on statistical considerations. An identical 'equivalent cell' was introduced, simplifying the array calculations. The procedure has been applied to voltage and current sources, series and parallel arrays, and four types of loads: matched load, constant resistant load, constant voltage, and constant current loads.

  15. Ultrasonic linear array validation via concrete test blocks

    SciTech Connect

    Hoegh, Kyle Khazanovich, Lev; Ferraro, Chris; Clayton, Dwight

    2015-03-31

    Oak Ridge National Laboratory (ORNL) comparatively evaluated the ability of a number of NDE techniques to generate an image of the volume of 6.5′ X 5.0′ X 10″ concrete specimens fabricated at the Florida Department of Transportation (FDOT) NDE Validation Facility in Gainesville, Florida. These test blocks were fabricated to test the ability of various NDE methods to characterize various placements and sizes of rebar as well as simulated cracking and non-consolidation flaws. The first version of the ultrasonic linear array device, MIRA [version 1], was one of 7 different NDE equipment used to characterize the specimens. This paper deals with the ability of this equipment to determine subsurface characterizations such as reinforcing steel relative size, concrete thickness, irregularities, and inclusions using Kirchhoff-based migration techniques. The ability of individual synthetic aperture focusing technique (SAFT) B-scan cross sections resulting from self-contained scans are compared with various processing, analysis, and interpretation methods using the various features fabricated in the specimens for validation. The performance is detailed, especially with respect to the limitations and implications for evaluation of a thicker, more heavily reinforced concrete structures.

  16. Synthesis arrangement and parity correction of linear array infrared detector

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Hong, Pu; Wang, Bo; Wang, Chensheng

    2010-11-01

    According to the configuration and technical specification of the detector, which has multiple channels, channels mixing, high speed outputs and separate columns between odd and even, a real time digital processing unit based on the CPLD, FPGA and DSP has been developed to achieve the data synthesis and arrangement function and the parity correction algorithm. A special interface circuit with 4 CPLDs is designed to complete the first synthesis step where the 16 channels of data are combined into 4 channels. The second step is finished in FPGA and ROM address encoder where the 4 channels of data are combined into 1 channel. For output data synchronization, FIFO is adopted to achieve the delay of even channels in the parity correction. Data of odd channels enters the columns synthesis unit without any processing and even channels shall be processed in the columns synthesis unit after entering the FIFO unit first and experiencing the delay process. Thereby the pre-processing before image processing of the linear array thermal imager is accomplished.

  17. Ultrasonic linear array validation via concrete test blocks

    NASA Astrophysics Data System (ADS)

    Hoegh, Kyle; Khazanovich, Lev; Ferraro, Chris; Clayton, Dwight

    2015-03-01

    Oak Ridge National Laboratory (ORNL) comparatively evaluated the ability of a number of NDE techniques to generate an image of the volume of 6.5' X 5.0' X 10″ concrete specimens fabricated at the Florida Department of Transportation (FDOT) NDE Validation Facility in Gainesville, Florida. These test blocks were fabricated to test the ability of various NDE methods to characterize various placements and sizes of rebar as well as simulated cracking and non-consolidation flaws. The first version of the ultrasonic linear array device, MIRA [version 1], was one of 7 different NDE equipment used to characterize the specimens. This paper deals with the ability of this equipment to determine subsurface characterizations such as reinforcing steel relative size, concrete thickness, irregularities, and inclusions using Kirchhoff-based migration techniques. The ability of individual synthetic aperture focusing technique (SAFT) B-scan cross sections resulting from self-contained scans are compared with various processing, analysis, and interpretation methods using the various features fabricated in the specimens for validation. The performance is detailed, especially with respect to the limitations and implications for evaluation of a thicker, more heavily reinforced concrete structures.

  18. Parallel Spectral Acquisition with an Ion Cyclotron Resonance Cell Array.

    PubMed

    Park, Sung-Gun; Anderson, Gordon A; Navare, Arti T; Bruce, James E

    2016-01-19

    Mass measurement accuracy is a critical analytical figure-of-merit in most areas of mass spectrometry application. However, the time required for acquisition of high-resolution, high mass accuracy data limits many applications and is an aspect under continual pressure for development. Current efforts target implementation of higher electrostatic and magnetic fields because ion oscillatory frequencies increase linearly with field strength. As such, the time required for spectral acquisition of a given resolving power and mass accuracy decreases linearly with increasing fields. Mass spectrometer developments to include multiple high-resolution detectors that can be operated in parallel could further decrease the acquisition time by a factor of n, the number of detectors. Efforts described here resulted in development of an instrument with a set of Fourier transform ion cyclotron resonance (ICR) cells as detectors that constitute the first MS array capable of parallel high-resolution spectral acquisition. ICR cell array systems consisting of three or five cells were constructed with printed circuit boards and installed within a single superconducting magnet and vacuum system. Independent ion populations were injected and trapped within each cell in the array. Upon filling the array, all ions in all cells were simultaneously excited and ICR signals from each cell were independently amplified and recorded in parallel. Presented here are the initial results of successful parallel spectral acquisition, parallel mass spectrometry (MS) and MS/MS measurements, and parallel high-resolution acquisition with the MS array system. PMID:26669509

  19. Acoustic trapping with a high frequency linear phased array

    NASA Astrophysics Data System (ADS)

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K. Kirk

    2012-11-01

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array.

  20. Modulation Transfer Function (MTF) measurement techniques for lenses and linear detector arrays

    NASA Technical Reports Server (NTRS)

    Schnabel, J. J., Jr.; Kaishoven, J. E., Jr.; Tom, D.

    1984-01-01

    Application is the determination of the Modulation Transfer Function (MTF) for linear detector arrays. A system set up requires knowledge of the MTF of the imaging lens. Procedure for this measurement is described for standard optical lab equipment. Given this information, various possible approaches to MTF measurement for linear arrays is described. The knife edge method is then described in detail.

  1. Simplified seawater alkalinity analysis: Use of linear array spectrometers

    NASA Astrophysics Data System (ADS)

    Yao, Wensheng; Byrne, Robert H.

    1998-08-01

    Modified spectrophotometric procedures are presented for the determination of seawater total alkalinity using rapid scan linear array spectrometers. Continuous monitoring of solution pH allows titrations to be terminated at relatively high pH, whereby excess acid terms are very small. Excess acid concentrations are quantified using the sulfonephthalein indicators, bromocresol green and bromocresol purple. The outlined spectrophotometric procedures require no thermal equilibration of samples. Using bromocresol green, solution pH T ([H +] T in moles per kg of solution) is given as: pHT=4.2699+0.002578(35- S)+ log((R(25)-0.00131)/(2.3148-0.1299 R(25))) - log(1-0.001005S) and R(25)= R( t){1+0.00909(25- t)}, where 29⩽S⩽37, 13° C⩽t⩽32° C, and R( t) is the absorbance ratio ( A616/ A444) at temperature t and salinity S. Using bromocresol purple, the solution pH T is given as pH T=5.8182+0.00129(35- S)+log(( R(25)-0.00381)/(2.8729-0.05104 R(25))) and R(25)= R( t){1+0.01869(25- t)}, where 29⩽S⩽37, 13° C⩽t⩽32° C, and R( t)= A589/ A432. Alkalinity measurements using bromocresol purple had a precision on the order of 0.3 μmol kg -1 and were within 0.3-0.9 μmol kg -1 of the alkalinities of certified seawater reference materials.

  2. A self-cohering technique for linear arrays using the Phase Gradient Autofocus Algorithm

    SciTech Connect

    Wahl, D.E.

    1991-02-01

    A towed linear hydrophone array is subject to snakelike bending. If the array were processed as if it were truly linear, poor array gain coupled with a degraded source bearing estimate would result. The signal phase errors produced by sensor position uncertainty in passive sonar arrays are similar to those observed in Synthetic Aperture Radar (SAR) imagery. The Phase Gradient Autofocus (PGA) Algorithm has been shown to be a robust and effective method used to extract degrading phase errors prevalent in SAR imagery. This report shows that with slight modifications, the PGA algorithm can be applied to correct phase errors resulting from sensor position uncertainty introduced into linear-passive arrays. The results of the technique applied to simulated linear array data is also presented. 9 refs., 8 figs.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  4. Iterative solutions of sparse linear systems on systolic arrays. Technical report

    SciTech Connect

    Melhem, R.

    1987-03-01

    The idea of grouping the non-zero elements of a sparse matrix into few strips that are almost parallel is applied to the design of a systolic accelerator for sparse matrix operations. This accelerator is, then, integrated into a complete systolic system for the solution of large sparse linear systems of equations. The design demonstrates that the application of systolic arrays is not limited to regular computations, and that computationally irregular problems may be solved on systolic networks if local storage is provided in each systolic cell for buffering the irregularity in the data movement and for absorbing the irregularity in the computation.

  5. Method of fabricating a solar cell array

    DOEpatents

    Lazzery, Angelo G.; Crouthamel, Marvin S.; Coyle, Peter J.

    1982-01-01

    A first set of pre-tabbed solar cells are assembled in a predetermined array with at least part of each tab facing upward, each tab being fixed to a bonding pad on one cell and abutting a bonding pad on an adjacent cell. The cells are held in place with a first vacuum support. The array is then inverted onto a second vacuum support which holds the tabs firmly against the cell pads they abut. The cells are exposed to radiation to melt and reflow the solder pads for bonding the tab portions not already fixed to bonding pads to these pads.

  6. Resonance Raman spectroscopic study of fused multiporphyrin linear arrays

    NASA Astrophysics Data System (ADS)

    Jeong, Dae Hong; Jang, Sung Moon; Hwang, In-Wook; Kim, Dongho; Matsuzaki, Yoichi; Tanaka, Kazuyoshi; Tsuda, Akihiko; Nakamura, Takeshi; Osuka, Atsuhiro

    2003-09-01

    For prospective applications as molecular electric wires, triply linked fused porphyrin arrays have been prepared. As expected from their completely flat molecular structures, π-electron delocalization can be extended to the whole array manifested by a continuous redshift of the HOMO-LUMO transition band to infrared region up to a few μm as the number of porphyrin units in the array increases. To gain an insight into the relationship between the molecular structures and electronic properties, we have investigated resonance Raman spectra of fused porphyrin arrays depending on the number of porphyrin pigments in the array. We have carried out the normal mode analysis of fused porphyrin dimer based on the experimental results including Raman frequency shifts of two types of 13C-isotope substituted dimers, Raman enhancement pattern by changing excitation wavelength, and depolarization ratio measurements as well as normal-mode calculations at the B3LYP/6-31G level. In order to find the origins for the resonance Raman mode enhancement mechanism, we have predicted both the excited state geometry changes (A-term) and the vibronic coupling efficiencies (B-term) for the relevant electronic transitions based on the INDO/S-SCI method. A detailed normal mode analysis of the fused dimer allows us to extend successfully our exploration to longer fused porphyrin arrays. Overall, our investigations have provided a firm basis in understanding the molecular vibrations of fused porphyrin arrays in relation to their unique flat molecular structures and rich electronic transitions.

  7. Superconducting-nanowire single-photon-detector linear array

    NASA Astrophysics Data System (ADS)

    Zhao, Qingyuan; McCaughan, Adam; Bellei, Francesco; Najafi, Faraz; De Fazio, Domenico; Dane, Andrew; Ivry, Yachin; Berggren, Karl K.

    2013-09-01

    We designed, fabricated, and tested a one-dimensional array of superconducting-nanowire single-photon detectors, integrated with on-chip inductors and resistors. The architecture is suitable for monolithic integration on a single chip operated in a cryogenic environment, and inherits the characteristics of individual superconducting-nanowire single-photon detectors. We demonstrated a working array with four pixels showing position discrimination and a timing jitter of 124 ps. The electronic crosstalk between the pixels in the array was negligible.

  8. Micromolded Arrays for Separation of Adherent Cells

    PubMed Central

    Wang, Yuli; Phillips, Colleen; Xu, Wei; Pai, Jeng-Hao; Dhopeshwarkar, Rahul; Sims, Christopher E.; Allbritton, Nancy

    2010-01-01

    We present an efficient, yet inexpensive, approach for isolating viable single cells or colonies from a mixed population. This cell microarray platform possesses innovations in both the array manufacture and the manner of target cell release. Arrays of microwells with bases composed of detachable concave elements, termed microrafts, were fabricated by a dip-coating process using a polydimethylsiloxane mold as the template and the array substrate. This manufacturing approach enabled the use of materials other than photoresists to create the array elements. Thus microrafts possessing low autofluorescence could be fabricated for fluorescence-based identification of cells. Cells plated on the microarray settled and attached at the center of the wells due to the microrafts’ concavity. Individual microrafts were readily dislodged by the action of a needle inserted through the compliant polymer substrate. The hard polymer material (polystyrene or epoxy resin) of which the microrafts were composed protected the cells from damage by the needle. For cell analysis and isolation, cells of interest were identified using a standard inverted microscope and microrafts carrying target cells were dislodged with the needle. The released cells/microrafts could be efficiently collected, cultured and clonally expanded. During the separation and collection procedures, the cells remained adherent and provided a measure of protection during manipulation, thus providing an extremely high single-cell cloning rate (>95%). Generation of a transfected cell line based on expression of a fluorescent protein demonstrated an important application for performing on-chip cell separations. PMID:20838672

  9. Real-time assessment of a linear pyroelectric sensor array for object classication

    NASA Astrophysics Data System (ADS)

    White, William E., III; Brown, Jeremy B.; Chari, Srikant; Jacobs, Eddie L.

    2010-10-01

    Pyroelectric linear arrays can be used to generate profiles of targets. Simulations have shown that generated profiles can be used to classify human and animal targets. A pyroelectric array system was used to collect data and classify targets as either human or non-human in real time. The pyroelectric array system consists of a 128-element Dias 128LTI pyroelectric linear array, an F/0.86 germanium lens, and an 18F4550 pic microcontroller for A/D conversion and communication. The classifier used for object recognition was trained using data collected in petting zoos and tested using data collected at the US-Mexico border in Arizona.

  10. Si Wire-Array Solar Cells

    NASA Astrophysics Data System (ADS)

    Boettcher, Shannon

    2010-03-01

    Micron-scale Si wire arrays are three-dimensional photovoltaic absorbers that enable orthogonalization of light absorption and carrier collection and hence allow for the utilization of relatively impure Si in efficient solar cell designs. The wire arrays are grown by a vapor-liquid-solid-catalyzed process on a crystalline (111) Si wafer lithographically patterned with an array of metal catalyst particles. Following growth, such arrays can be embedded in polymethyldisiloxane (PDMS) and then peeled from the template growth substrate. The result is an unusual photovoltaic material: a flexible, bendable, wafer-thickness crystalline Si absorber. In this paper I will describe: 1. the growth of high-quality Si wires with controllable doping and the evaluation of their photovoltaic energy-conversion performance using a test electrolyte that forms a rectifying conformal semiconductor-liquid contact 2. the observation of enhanced absorption in wire arrays exceeding the conventional light trapping limits for planar Si cells of equivalent material thickness and 3. single-wire and large-area solid-state Si wire-array solar cell results obtained to date with directions for future cell designs based on optical and device physics. In collaboration with Michael Kelzenberg, Morgan Putnam, Joshua Spurgeon, Daniel Turner-Evans, Emily Warren, Nathan Lewis, and Harry Atwater, California Institute of Technology.

  11. Multiview Hilbert transformation for full-view photoacoustic computed tomography using a linear array

    NASA Astrophysics Data System (ADS)

    Li, Guo; Li, Lei; Zhu, Liren; Xia, Jun; Wang, Lihong V.

    2015-06-01

    Due to their low cost, hand-held convenience, wide selection of bandwidths, and ultrasound imaging capability, linear ultrasonic transducer arrays have been widely studied for photoacoustic computed tomography (PACT). As linear-array PACT suffers from a limited view, full-view imaging requires either the transducer or the object to be rotated. So far, both the central frequencies and bandwidth of linear transducer arrays applied in full-view PACT are low, limiting the spatial resolutions of the reconstructed images. Here, we present a multiview high-frequency PACT imaging system implemented with a commercial 40-MHz central frequency linear transducer array. By rotating the object through multiple angles with respect to the linear transducer array, we acquired full-view photoacoustic pressure measurements. Further, to quantify the unipolar initial pressures and overcome the limitations of the single-view Hilbert transformation, we developed a multiview Hilbert transformation method. The in-plane spatial resolution of this full-view linear-array PACT was quantified to be isotropically 60 μm within a 10×10 mm2 field of view. The system was demonstrated by imaging both a leaf skeleton and a zebrafish in vivo.

  12. Multiview Hilbert transformation for full-view photoacoustic computed tomography using a linear array

    PubMed Central

    Li, Guo; Li, Lei; Zhu, Liren; Xia, Jun; Wang, Lihong V.

    2015-01-01

    Abstract. Due to their low cost, hand-held convenience, wide selection of bandwidths, and ultrasound imaging capability, linear ultrasonic transducer arrays have been widely studied for photoacoustic computed tomography (PACT). As linear-array PACT suffers from a limited view, full-view imaging requires either the transducer or the object to be rotated. So far, both the central frequencies and bandwidth of linear transducer arrays applied in full-view PACT are low, limiting the spatial resolutions of the reconstructed images. Here, we present a multiview high-frequency PACT imaging system implemented with a commercial 40-MHz central frequency linear transducer array. By rotating the object through multiple angles with respect to the linear transducer array, we acquired full-view photoacoustic pressure measurements. Further, to quantify the unipolar initial pressures and overcome the limitations of the single-view Hilbert transformation, we developed a multiview Hilbert transformation method. The in-plane spatial resolution of this full-view linear-array PACT was quantified to be isotropically 60  μm within a 10×10  mm2 field of view. The system was demonstrated by imaging both a leaf skeleton and a zebrafish in vivo. PMID:26112369

  13. Broadening cell selection criteria with micropallet arrays of adherent cells.

    PubMed

    Wang, Yuli; Young, Grace; Aoto, Phillip C; Pai, Jeng-Hao; Bachman, Mark; Li, G P; Sims, Christopher E; Allbritton, Nancy L

    2007-10-01

    A host of technologies exists for the separation of living, nonadherent cells, with separation decisions typically based on fluorescence or immunolabeling of cells. Methods to separate adherent cells as well as to broaden the range of possible sorting criteria would be of high value and complementary to existing strategies. Cells were cultured on arrays of releasable pallets. The arrays were screened and individual cell(s)/pallets were released and collected. Conventional fluorescence and immunolabeling of cells were compatible with the pallet arrays, as were separations based on gene expression. By varying the size of the pallet and the number of cells cultured on the array, single cells or clonal colonies of cells were isolated from a heterogeneous population. Since cells remained adherent throughout the isolation process, separations based on morphologic characteristics, for example cell shape, were feasible. Repeated measurements of each cell in an array were performed permitting the selection of cells based on their temporal behavior, e.g. growth rate. The pallet array system provides the flexibility to select and collect adherent cells based on phenotypic and temporal criteria and other characteristics not accessible by alternative methods. PMID:17559133

  14. Methods for Characterizing the System Functions of Ultrasonic Linear Phased Array Inspection Systems

    NASA Astrophysics Data System (ADS)

    Huang, Ruiju; Schmerr, Lester W.

    2008-02-01

    This work characterizes all the electrical and electromechanical aspects of a linear phased array system, using a matrix of system functions that are obtained from the measured response of the array elements in a simple reference experiment. It is shown that for the arrays tested all these system functions are essentially identical, allowing one to use a single system function to characterize the entire array, as done for an ordinary single element transducer. The variation of this single system function with the number of elements firing in the array or with changes of the delay law used is described. It is also demonstrated that once such a single system function is obtained for an array, it can be used in a complete ultrasonic measurement model to accurately predict the array response measured from of a reference reflector in an immersion setup.

  15. Cell membrane array fabrication and assay technology

    PubMed Central

    Yamazaki, Victoria; Sirenko, Oksana; Schafer, Robert J; Nguyen, Luat; Gutsmann, Thomas; Brade, Lore; Groves, Jay T

    2005-01-01

    Background Microarray technology has been used extensively over the past 10 years for assessing gene expression, and has facilitated precise genetic profiling of everything from tumors to small molecule drugs. By contrast, arraying cell membranes in a manner which preserves their ability to mediate biochemical processes has been considerably more difficult. Results In this article, we describe a novel technology for generating cell membrane microarrays for performing high throughput biology. Our robotically-arrayed supported membranes are physiologically fluid, a critical property which differentiates this technology from other previous membrane systems and makes it useful for studying cellular processes on an industrialized scale. Membrane array elements consist of a solid substrate, above which resides a fluid supported lipid bilayer containing biologically-active molecules of interest. Incorporation of transmembrane proteins into the arrayed membranes enables the study of ligand/receptor binding, as well as interactions with live intact cells. The fluidity of these molecules in the planar lipid bilayer facilitates dimerization and other higher order interactions necessary for biological signaling events. In order to demonstrate the utility of our fluid membrane array technology to ligand/receptor studies, we investigated the multivalent binding of the cholera toxin B-subunit (CTB) to the membrane ganglioside GM1. We have also displayed a number of bona fide drug targets, including bacterial endotoxin (also referred to as lipopolysaccharide (LPS)) and membrane proteins important in T cell activation. Conclusion We have demonstrated the applicability of our fluid cell membrane array technology to both academic research applications and industrial drug discovery. Our technology facilitates the study of ligand/receptor interactions and cell-cell signaling, providing rich qualitative and quantitative information. PMID:15960850

  16. Low cost solar cell arrays

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Mclennan, H.

    1975-01-01

    Limitations in both space and terrestial markets for solar cells are described. Based on knowledge of the state-of-the-art, six cell options are discussed; as a result of this discussion, the three most promising options (involving high, medium and low efficiency cells respectively) were selected and analyzed for their probable costs. The results showed that all three cell options gave promise of costs below $10 per watt in the near future. Before further cost reductions can be achieved, more R and D work is required; suggestions for suitable programs are given.

  17. Interlaced linear array sampling technique for electromagnetic wave imaging

    SciTech Connect

    Sheen, David M; McMakin, Douglas L

    2009-06-16

    An arrangement of receivers and transmitters used in wideband holographic imaging using a reduced number of physical antenna elements compared to established techniques and systems. At least one of the receivers is configured to receive the reflected signal from three or more of transmitters, and at least one transmitter is configured to transmit a signal to an object, the reflection of which will be received by at least three receivers. The improved arrays are easily incorporated into existing microwave and millimeter wave holographic imaging equipment utilizing the existing mechanical features of this equipment, as well as the existing wideband holographic imaging algorithms and electronics for constructing images.

  18. Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

    PubMed Central

    Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

  19. Linearized superconducting quantum interference device array for high bandwidth frequency-domain readout multiplexing.

    PubMed

    Lanting, T; Dobbs, M; Spieler, H; Lee, A T; Yamamoto, Y

    2009-09-01

    We have designed and demonstrated a superconducting quantum interference device (SQUID) array linearized with cryogenic feedback. To achieve the necessary loop gain, a 300-element series array SQUID is constructed from three monolithic 100-element series arrays. A feedback resistor completes the loop from the SQUID output to the input coil. The short feedback path of this linearized SQUID array (LISA) allows for a substantially larger flux-locked loop bandwidth as compared to a SQUID flux-locked loop that includes a room temperature amplifier. The bandwidth, linearity, noise performance, and 3 Phi(0) dynamic range of the LISA are sufficient for its use in our target application: the multiplexed readout of transition-edge sensor bolometers. PMID:19791952

  20. Microfabricated Cell-based Biosensor Arrays.

    PubMed

    Pishko, Michael

    2005-01-01

    Here, we described the fabrication using photolithography of poly(ethylene glycol) (PEG)-based hydrogel microstructures encapsulating viable mammalian cells on glass and silicon substrates. Substrates were treated with 3-(trichlorosilyl) propyl methacrylate to form pendant acrylate group to covalent link the hydrogel microstructure. Cells were encapsulated in arrays of cylindrical hydrogel microstructures 600 and 50 μm in diameter and viability assays demonstrated that encapsulated cells remained viable after photoencapsulation. These microstructures had clearly defined, three-dimensional structure without any residual cells remaining surface and no delamination of hydrogel elements from functionalized substrate occurred in aqueous environment for over a week. By changing spin-coating rates and feature sizes of photomasks, we could create cell-containing microstructures with aspect ratios ranging from 0.12 to 1.4. In case of 50 μm hydrogel microstructure, number of cells could be limited to 1 or 2 cells per element and array consisting of 400 elements could be fabricated in a square of 2 mm2. These cell-containinghydrogel microstructures were also successfully fabricated in poly(dimethylsiloxane) microchannels to create optical biosensor arrays of individually addressable single or multiple cell- containing hydrogel microstructures with potential applications in drug screening or pathogen detection. PMID:17282370

  1. 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.

  2. Elastomer Encapsulant for Solar-Cell Arrays

    NASA Technical Reports Server (NTRS)

    Baum, B.; Willis, P. B.

    1985-01-01

    Butyl acrylate syrups useful potting compounds for encapsulating photovoltaic cells in modular arrays. Material pourable liquid pumped into module, then cured to rubbery consistency. Cured material is thermoset elastomer highly transparent, low cost, flexible and with good low-temperature properties.

  3. Low cost silicon solar cell array

    NASA Technical Reports Server (NTRS)

    Bartels, F. T. C.

    1974-01-01

    The technological options available for producing low cost silicon solar cell arrays were examined. A project value of approximately $250/sq m and $2/watt is projected, based on mass production capacity demand. Recommendations are included for the most promising cost reduction options.

  4. Fast ultrasound beam prediction for linear and regular two-dimensional arrays.

    PubMed

    Hlawitschka, Mario; McGough, Robert J; Ferrara, Katherine W; Kruse, Dustin E

    2011-09-01

    Real-time beam predictions are highly desirable for the patient-specific computations required in ultrasound therapy guidance and treatment planning. To address the longstanding issue of the computational burden associated with calculating the acoustic field in large volumes, we use graphics processing unit (GPU) computing to accelerate the computation of monochromatic pressure fields for therapeutic ultrasound arrays. In our strategy, we start with acceleration of field computations for single rectangular pistons, and then we explore fast calculations for arrays of rectangular pistons. For single-piston calculations, we employ the fast near-field method (FNM) to accurately and efficiently estimate the complex near-field wave patterns for rectangular pistons in homogeneous media. The FNM is compared with the Rayleigh-Sommerfeld method (RSM) for the number of abscissas required in the respective numerical integrations to achieve 1%, 0.1%, and 0.01% accuracy in the field calculations. Next, algorithms are described for accelerated computation of beam patterns for two different ultrasound transducer arrays: regular 1-D linear arrays and regular 2-D linear arrays. For the array types considered, the algorithm is split into two parts: 1) the computation of the field from one piston, and 2) the computation of a piston-array beam pattern based on a pre-computed field from one piston. It is shown that the process of calculating an array beam pattern is equivalent to the convolution of the single-piston field with the complex weights associated with an array of pistons. Our results show that the algorithms for computing monochromatic fields from linear and regularly spaced arrays can benefit greatly from GPU computing hardware, exceeding the performance of an expensive CPU by more than 100 times using an inexpensive GPU board. For a single rectangular piston, the FNM method facilitates volumetric computations with 0.01% accuracy at rates better than 30 ns per field point

  5. Isotropic-resolution linear-array-based photoacoustic computed tomography through inverse Radon transform

    NASA Astrophysics Data System (ADS)

    Li, Guo; Xia, Jun; Li, Lei; Wang, Lidai; Wang, Lihong V.

    2015-03-01

    Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.

  6. Linear CCD attitude measurement system based on the identification of the auxiliary array CCD

    NASA Astrophysics Data System (ADS)

    Hu, Yinghui; Yuan, Feng; Li, Kai; Wang, Yan

    2015-10-01

    Object to the high precision flying target attitude measurement issues of a large space and large field of view, comparing existing measurement methods, the idea is proposed of using two array CCD to assist in identifying the three linear CCD with multi-cooperative target attitude measurement system, and to address the existing nonlinear system errors and calibration parameters and more problems with nine linear CCD spectroscopic test system of too complicated constraints among camera position caused by excessive. The mathematical model of binocular vision and three linear CCD test system are established, co-spot composition triangle utilize three red LED position light, three points' coordinates are given in advance by Cooperate Measuring Machine, the red LED in the composition of the three sides of a triangle adds three blue LED light points as an auxiliary, so that array CCD is easier to identify three red LED light points, and linear CCD camera is installed of a red filter to filter out the blue LED light points while reducing stray light. Using array CCD to measure the spot, identifying and calculating the spatial coordinates solutions of red LED light points, while utilizing linear CCD to measure three red LED spot for solving linear CCD test system, which can be drawn from 27 solution. Measured with array CCD coordinates auxiliary linear CCD has achieved spot identification, and has solved the difficult problems of multi-objective linear CCD identification. Unique combination of linear CCD imaging features, linear CCD special cylindrical lens system is developed using telecentric optical design, the energy center of the spot position in the depth range of convergence in the direction is perpendicular to the optical axis of the small changes ensuring highprecision image quality, and the entire test system improves spatial object attitude measurement speed and precision.

  7. System performance and performance enhancement relative to element position location errors for distributed linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Adrian, Andrew

    For the most part, antenna phased arrays have traditionally been comprised of antenna elements that are very carefully and precisely placed in very periodic grid structures. Additionally, the relative positions of the elements to each other are typically mechanically fixed as best as possible. There is never an assumption the relative positions of the elements are a function of time or some random behavior. In fact, every array design is typically analyzed for necessary element position tolerances in order to meet necessary performance requirements such as directivity, beamwidth, sidelobe level, and beam scanning capability. Consider an antenna array that is composed of several radiating elements, but the position of each of the elements is not rigidly, mechanically fixed like a traditional array. This is not to say that the element placement structure is ignored or irrelevant, but each element is not always in its relative, desired location. Relative element positioning would be analogous to a flock of birds in flight or a swarm of insects. They tend to maintain a near fixed position with the group, but not always. In the antenna array analog, it would be desirable to maintain a fixed formation, but due to other random processes, it is not always possible to maintain perfect formation. This type of antenna array is referred to as a distributed antenna array. A distributed antenna array's inability to maintain perfect formation causes degradations in the antenna factor pattern of the array. Directivity, beamwidth, sidelobe level and beam pointing error are all adversely affected by element relative position error. This impact is studied as a function of element relative position error for linear antenna arrays. The study is performed over several nominal array element spacings, from lambda to lambda, several sidelobe levels (20 to 50 dB) and across multiple array illumination tapers. Knowing the variation in performance, work is also performed to utilize a minimum

  8. A Wide Dynamic Range Tapped Linear Array Image Sensor

    NASA Astrophysics Data System (ADS)

    Washkurak, William D.; Chamberlain, Savvas G.; Prince, N. Daryl

    1988-08-01

    magnitide are obtained. To achieve the short integration times necessary in acousto-optic applications. t he wide dynamic range detector has been implemented into a tapped array architecture with eight outputs and 256 photoelements. Operation of each 01)1,1)111 at 16 MHz yields detector integration times of 2 micro-seconds. Buried channel two phase CCD shift register technology is utilized to minimize image sensor noise improve video output rates and increase ease of operation.

  9. Effect of finite rectangular groundplane on near-in sidelobes of small linear slotted waveguide arrays

    NASA Astrophysics Data System (ADS)

    McNamara, D. A.; Botha, L.

    1989-06-01

    The geometric theory of diffraction is used here to examine the effect of finite rectangular groundplane (FGP) size on the sidelobe level (SLL) of a 10-element linear slotted waveguide array. The results provide an idea of the order of magnitude of FGP effects on the near-in SLLs. They provide the designer with an indication of the 'overdesign' required for satisfactory development of an array whose SLL specifications are firm.

  10. New Fabrication of High-Frequency (100-MHz) Ultrasound PZT Film Kerfless Linear Array

    PubMed Central

    Zhu, Benpeng; Chan, Ngai Yui; Dai, Jiyan; Shung, K. Kirk; Takeuchi, Shinichi; Zhou, Qifa

    2013-01-01

    The paper describes the design, fabrication, and measurements of a high-frequency ultrasound kerfless linear array prepared from hydrothermal lead zirconate titanate (PZT) thick film. The 15-µm hydrothermal PZT thick film with an area of 1 × 1 cm, obtained through a self-separation process from Ti substrate, was used to fabricate a 32-element 100-MHz kerfless linear array with photolithography. The bandwidth at −6 dB without matching layer, insertion loss around center frequency, and crosstalk between adjacent elements were measured to be 39%, −30 dB, and −15 dB, respectively. PMID:23549547

  11. Linear micromirror array for broadband femtosecond pulse shaping in phase and amplitude

    NASA Astrophysics Data System (ADS)

    Weber, Stefan M.; Waldis, Severin; Noell, Wilfried; Kiselev, Denis; Extermann, Jérôme; Bonacina, Luigi; Wolf, Jean-Pierre; de Rooij, Nico F.

    2009-02-01

    We are developing a linear array of micromirrors designed for optical, femtosecond laser pulse shaping. It is a bulkmicromachined device, capable of retarding or diminishing certain laser frequencies in order to perform phase and amplitude modulation within a frequency band spanning the UV to the near-infrared. The design consists of a linear array of mirrors fixed on either side by springs. They feature two degrees of freedom: Out-of-plane motion for phase shifting and rotational motion for binary amplitude modulation, both realized using vertical comb drives. The first applications will include femtosecond discrimination experiments on biomolecules.

  12. Cell adhesion and guidance by micropost-array chemical sensors

    NASA Astrophysics Data System (ADS)

    Pantano, Paul; Quah, Soo-Kim; Danowski, Kristine L.

    2002-06-01

    An array of ~50,000 individual polymeric micropost sensors was patterned across a glass coverslip by a photoimprint lithographic technique. Individual micropost sensors were ~3-micrometers tall and ~8-micrometers wide. The O2-sensitive micropost array sensors (MPASs) comprised a ruthenium complex encapsulated in a gas permeable photopolymerizable siloxane. The pH-sensitive MPASs comprised a fluorescein conjugate encapsulated in a photocrosslinkable poly(vinyl alcohol)-based polymer. PO2 and pH were quantitated by acquiring MPAS luminescence images with an epifluorescence microscope/charge coupled device imaging system. O2-sensitive MPASs displayed linear Stern-Volmer quenching behavior with a maximum Io/I of ~8.6. pH-sensitive MPASs displayed sigmoidal calibration curves with a pKa of ~5.8. The adhesion of undifferentiated rat pheochromocytoma (PC12) cells across these two polymeric surface types was investigated. The greatest PC12 cell proliferation and adhesion occurred across the poly(vinyl alcohol)-based micropost arrays relative to planar poly(vinyl alcohol)-based surfaces and both patterned and planar siloxane surfaces. An additional advantage of the patterned MPAS layers relative to planar sensing layers was the ability to direct the growth of biological cells. Preliminary data is presented whereby nerve growth factor-differentiated PC12 cells grew neurite-like processes that extended along paths defined by the micropost architecture.

  13. Parametric Studies Of Lightweight Reflectors Supported On Linear Actuator Arrays

    NASA Astrophysics Data System (ADS)

    Seibert, George E.

    1987-10-01

    , describes the extent to which the deflection under a point force is localized by the shell's curvature. The deflection shape is typically a near-gaussian "bump" with a zero-crossing at a local radius of approximately 3.5 characteristic lengths. The amplitude is a function of the shells elastic modulus, radius, and thickness, and is linearly proportional to the applied force. This basic shell behavior is well-treated in an excellent set of papers by Eric Reissner entitled "Stresses and Small Displacements of Shallow Spherical Shells".1'2 Building on the insight offered by these papers, we developed our design tools around two derived parameters, the ratio of the mirror's diameter to its characteristic length (D/l), and the ratio of the actuator spacing to the characteristic length (b/l). The D/1 ratio determines the "finiteness" of the shell, or its dependence on edge boundary conditions. For D/1 values greater than 10, the influence of edges is almost totally absent on interior behavior. The b/1 ratio, the basis of all our normalizations is the most universal term in the description of correctability or ratio of residual/input errors. The data presented in the paper, shows that the rms residual error divided by the peak amplitude of the input error function is related to the actuator spacing to characteristic length ratio by the following expression RMS Residual Error b 3.5 k (I) (1) Initial Error Ampl. The value of k ranges from approximately 0.001 for low spatial frequency initial errors up to 0.05 for higher error frequencies (e.g. 5 cycles/diameter). The studies also yielded insight to the forces required to produce typical corrections at both the center and edges of the mirror panels. Additionally, the data lends itself to rapid evaluation of the effects of trading faceplate weight for increased actuator count,

  14. Geometric Correction of Airborne Linear Array Image Based on Bias Matrix

    NASA Astrophysics Data System (ADS)

    Wang, M.; Hu, J.; Zhou, M.; Li, J. M.; Zhang, Z.

    2013-05-01

    As the linear array sensor has great potential in disaster monitoring, geological survey, the quality of the image geometric correction should be guaranteed. The primary focus of this paper is to present a new method correcting airbone linear image based on the bias matrix,which is bulit by describing and analysing the errors of airbone linear image included the misalignment. The bias matrix was considered as additional observations to the traditional geometric correction model in our method. And by using control points which have both image coordinate and object coordinate, the solving equation from geometric correction model can be established and the bias matrix can be calculated by adjustment strategy. To avoid the singularity problem in the calculating process, this paper uses quaternion to describe the image's attitude and rotation instead of traditional calculating method which is structured by the Euler angle. Finally, geometric correction of airborne linear array image with high accuracy based on bias matrix can be achieved.

  15. (abstract) Scaling Nominal Solar Cell Impedances for Array Design

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L; Wallace, Matthew T.; Iles, Peter

    1994-01-01

    This paper discusses a task the objective of which is to characterize solar cell array AC impedance and develop scaling rules for impedance characterization of large arrays by testing single solar cells and small arrays. This effort is aimed at formulating a methodology for estimating the AC impedance of the Mars Pathfinder (MPF) cruise and lander solar arrays based upon testing single cells and small solar cell arrays and to create a basis for design of a single shunt limiter for MPF power control of flight solar arrays having very different inpedances.

  16. On resolving 2M - 1 narrow-band signals with an M sensor uniform linear array

    NASA Technical Reports Server (NTRS)

    Williams, Douglas B.; Johnson, Don H.

    1992-01-01

    Length 2M real signal vectors are used to address the problem of determining the maximum number of narrow-band signals whose parameters can be estimated with a linear array of M equally spaced sensors. It is shown that 2M of these real vectors are linearly independent with probability one, and, thus in the presence of additive white noise, the parameters of 2M - 1 signals can be estimated. An algorithm for determining directions and amplitudes is presented.

  17. Bipolar battery with array of sealed cells

    DOEpatents

    Kaun, Thomas D.; Smaga, John A.

    1987-01-01

    A lithium alloy/metal sulfide battery as a dipolar battery is disclosed with an array of stacked cells with the anode and cathode electrode materials in each cell sealed in a confining structure and separated from one another except across separator material interposed therebetween. The separator material is contained in a module having separate perforated metallic sheets that sandwich opposite sides of the separator material for the cell and an annular insulating spacer that surrounds the separator material beyond the perforations and is also sandwiched between and sealed to the sheets. The peripheral edges of the sheets project outwardly beyond the spacer, traverse the side edges of the adjacent electrode material to form cup-like electrode holders, and are fused to the adjacent current collector or end face members of the array. Electrolyte is infused into the electrolyte cavity through the perforations of one of the metallic sheets with the perforations also functioning to allow ionic conductance across the separator material between the adjacent electrodes. A gas-tight housing provides an enclosure of the array.

  18. Room acoustics investigations of beamforming performance using coprime linear microphone arrays

    NASA Astrophysics Data System (ADS)

    Bush, Dane

    Linear microphone arrays are powerful tools for determining the direction of a sound source. Traditionally, uniform linear arrays (ULA) have inter-element spacing of half of the wavelength in question. This produces the narrowest possible beam without introducing grating lobes -- a form of aliasing governed by the spatial Nyquist theorem. Grating lobes are often undesirable because they make direction of arrival indistinguishable among their passband angles. Exploiting coprime number theory however, an array can be arranged sparsely with fewer total elements, exceeding the aforementioned spatial sampling limit separation. Two sparse ULA sub-arrays with coprime number of elements, when nested properly, each produce narrow grating lobes that overlap with one another exactly in just one direction. By combining the sub-array outputs it is possible to retain the shared beam while mostly canceling the other superfluous grating lobes. In this work beam patterns are simulated for a range of single frequencies, as well as for arbitrary bands of frequencies. Three coprime microphone arrays are built with different lengths and sub-array spacings. Two different techniques are explored for sub-array data processing and combination. Experimental beam patterns are shown to correspond with simulated results even at frequencies other than the array's design frequency. Beam width and side lobe locations are shown to correspond to the derived values. Side lobes in the directional pattern are mitigated by increasing bandwidth of analyzed signals. Accurate single-source direction of arrival (DOA) estimation is shown to be possible in free field and reverberant conditions. DOA estimation is also implemented for two simultaneous noise sources in the free field condition. Room reflections can be resolved in the reverberant condition, provided adequate reduction of side lobes.

  19. Digital Cell Counting Device Integrated with a Single-Cell Array

    PubMed Central

    Saeki, Tatsuya; Hosokawa, Masahito; Lim, Tae-kyu; Harada, Manabu; Matsunaga, Tadashi; Tanaka, Tsuyoshi

    2014-01-01

    In this paper, we present a novel cell counting method accomplished using a single-cell array fabricated on an image sensor, complementary metal oxide semiconductor sensor. The single-cell array was constructed using a microcavity array, which can trap up to 7,500 single cells on microcavities periodically arranged on a plane metallic substrate via the application of a negative pressure. The proposed method for cell counting is based on shadow imaging, which uses a light diffraction pattern generated by the microcavity array and trapped cells. Under illumination, the cell-occupied microcavities are visualized as shadow patterns in an image recorded by the complementary metal oxide semiconductor sensor due to light attenuation. The cell count is determined by enumerating the uniform shadow patterns created from one-on-one relationships with single cells trapped on the microcavities in digital format. In the experiment, all cell counting processes including entrapment of non-labeled HeLa cells from suspensions on the array and image acquisition of a wide-field-of-view of 30 mm2 in 1/60 seconds were implemented in a single integrated device. As a result, the results from the digital cell counting had a linear relationship with those obtained from microscopic observation (r2 = 0.99). This platform could be used at extremely low cell concentrations, i.e., 25–15,000 cells/mL. Our proposed system provides a simple and rapid miniaturized cell counting device for routine laboratory use. PMID:24551208

  20. Advanced cell designs for welded arrays

    SciTech Connect

    Giuliano, M.; Wohlgemuth, J.

    1982-08-01

    In this paper the authors present some solar cell design innovations and associated process technology which can result in practical welded contacts for interconnection into arrays. The principal problem with welded contacts on solar cells relates to electrical and mechanical damage to the shallow diffused front junction of the cell. Design approaches are presented which result in a deeper pn junction under the weld contact point. This moves the location of the junction to a safer distance below the region of heat and pressure resulting from the welding operation. The methods presented can be used with various welding techniques including parallel gap welding, ultrasonic welding, laser spot welding or thermo-compression bonding. Design approaches include the development of a eutectic bonding technique to provide weldable contacts on front and back of the solar cell, as well as a novel integral feedthrough approach which permits welding of both contacts on the back of the cell.

  1. a Method for Self-Calibration in Satellite with High Precision of Space Linear Array Camera

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Qian, Fangming; Miao, Yuzhe; Wang, Rongjian

    2016-06-01

    At present, the on-orbit calibration of the geometric parameters of a space surveying camera is usually processed by data from a ground calibration field after capturing the images. The entire process is very complicated and lengthy and cannot monitor and calibrate the geometric parameters in real time. On the basis of a large number of on-orbit calibrations, we found that owing to the influence of many factors, e.g., weather, it is often difficult to capture images of the ground calibration field. Thus, regular calibration using field data cannot be ensured. This article proposes a real time self-calibration method for a space linear array camera on a satellite using the optical auto collimation principle. A collimating light source and small matrix array CCD devices are installed inside the load system of the satellite; these use the same light path as the linear array camera. We can extract the location changes of the cross marks in the matrix array CCD to determine the real-time variations in the focal length and angle parameters of the linear array camera. The on-orbit status of the camera is rapidly obtained using this method. On one hand, the camera's change regulation can be mastered accurately and the camera's attitude can be adjusted in a timely manner to ensure optimal photography; in contrast, self-calibration of the camera aboard the satellite can be realized quickly, which improves the efficiency and reliability of photogrammetric processing.

  2. A 3-D microfluidic combinatorial cell array.

    PubMed

    Liu, Mike C; Tai, Yu-Chong

    2011-02-01

    We present the development of a three-dimensional (3-D) combinatorial cell culture array device featured with integrated three-input, eight-output combinatorial mixer and cell culture chambers. The device is designed for cell-based screening of multiple compounds simultaneously on a microfluidic platform. The final assembled device is composed of a porous membrane integrated in between a Parylene 3-D microfluidic chip and a PDMS microfluidic chip. The membrane turned the cell culture chambers into two-level configuration to facilitate cell loading and to maintain cells in a diffusion dominated space during device operation. Experimentally, we first characterized the combined compound concentration profile at each chamber using a fluorescence method. We then successfully demonstrated the functionality of the quantitative cell-based assay by culturing B35 rat neuronal cells on this device and screening the ability of three compounds (1,5-dihydroxyisoquinoline, deferoxamine, and 3-aminobenzoic acid) to attenuate cell death caused by cytotoxic hydrogen peroxide. In another experiment, we assayed for the combinatorial effects of three chemotherapeutic compound exposures (vinorelbine, paclitaxel, and γ-linolenic acid) on human breast cancer cells, MDA-MB-231. The same technology will enable the construction of inexpensive lab-on-a-chip devices with high-input combinatorial mixer for performing high-throughput cell-based assay and highly parallel and combinatorial chemical or biochemical reactions. PMID:21063783

  3. Optimization of element length for imaging small volumetric reflectors with linear ultrasonic arrays

    NASA Astrophysics Data System (ADS)

    Barber, T. S.; Wilcox, P. D.; Nixon, A. D.

    2016-02-01

    A 3D ultrasonic simulation study is presented, aimed at understanding the effect of element length for imaging small volumetric flaws with linear arrays in ultrasonically noisy materials. The geometry of a linear array can be described by the width, pitch and total number of the elements along with the length perpendicular to imaging plane. This paper is concerned with the latter parameter, which tends to be ignored in array optimization studies and is often chosen arbitrarily for industrial array inspections. A 3D analytical model based on imaging a point target is described, validated and used to make calculations of relative Signal-to-Noise Ratio (SNR) as a function of element length. SNR is found to be highly sensitive to element length with a 12dB variation observed over the length range investigated. It is then demonstrated that the optimal length can be predicted directly from the Point Spread Function (PSF) of the imaging system as well as the natural focal point of the array element from 2D beam profiles perpendicular to the imaging plane. This result suggests that the optimal length for any imaging position can be predicted without the need for a full 3D model and is independent of element pitch and the number of elements. Array element design guidelines are then described with respect to wavelength and extensions of these results are discussed for application to realistically-sized defects and coarse-grained materials.

  4. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

    NASA Astrophysics Data System (ADS)

    Hoyos, Mauricio; Moore, Lee; Williams, P. Stephen; Zborowski, Maciej

    2011-05-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of a parallel plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest.

  5. Linear array implementation of the EM algorithm for PET image reconstruction

    SciTech Connect

    Rajan, K.; Patnaik, L.M.; Ramakrishna, J.

    1995-08-01

    The PET image reconstruction based on the EM algorithm has several attractive advantages over the conventional convolution back projection algorithms. However, the PET image reconstruction based on the EM algorithm is computationally burdensome for today`s single processor systems. In addition, a large memory is required for the storage of the image, projection data, and the probability matrix. Since the computations are easily divided into tasks executable in parallel, multiprocessor configurations are the ideal choice for fast execution of the EM algorithms. In tis study, the authors attempt to overcome these two problems by parallelizing the EM algorithm on a multiprocessor systems. The parallel EM algorithm on a linear array topology using the commercially available fast floating point digital signal processor (DSP) chips as the processing elements (PE`s) has been implemented. The performance of the EM algorithm on a 386/387 machine, IBM 6000 RISC workstation, and on the linear array system is discussed and compared. The results show that the computational speed performance of a linear array using 8 DSP chips as PE`s executing the EM image reconstruction algorithm is about 15.5 times better than that of the IBM 6000 RISC workstation. The novelty of the scheme is its simplicity. The linear array topology is expandable with a larger number of PE`s. The architecture is not dependant on the DSP chip chosen, and the substitution of the latest DSP chip is straightforward and could yield better speed performance.

  6. A Low-Complexity ESPRIT-Based DOA Estimation Method for Co-Prime Linear Arrays.

    PubMed

    Sun, Fenggang; Gao, Bin; Chen, Lizhen; Lan, Peng

    2016-01-01

    The problem of direction-of-arrival (DOA) estimation is investigated for co-prime array, where the co-prime array consists of two uniform sparse linear subarrays with extended inter-element spacing. For each sparse subarray, true DOAs are mapped into several equivalent angles impinging on the traditional uniform linear array with half-wavelength spacing. Then, by applying the estimation of signal parameters via rotational invariance technique (ESPRIT), the equivalent DOAs are estimated, and the candidate DOAs are recovered according to the relationship among equivalent and true DOAs. Finally, the true DOAs are estimated by combining the results of the two subarrays. The proposed method achieves a better complexity-performance tradeoff as compared to other existing methods. PMID:27571079

  7. Real-time photoacoustic imaging based on multielement linear transducer array

    NASA Astrophysics Data System (ADS)

    Yin, Bangzheng; Xing, Da; Wang, Yi; Zeng, Yaguang; Tan, Yi

    2005-01-01

    A real-time photoacoustic (PA) imaging system based on multi-element linear transducer array was developed and test on phantoms. A Q switched Nd:YAG laser operating at 532 nm and 20Hz repeat rate was used in our experiment as thermal source. The multi-element linear transducer array consists of 320 elements. By phase-controlled method, 64 signals, one of which gathered by 11-group element, make up of an image. It was acquired in only about 3 seconds. Phantom experiment results can map the distribution of the optical absorption correctly. Compared to other existing technology and algorithm, the PA imaging based on transducer array was characterize by speediness and convenience. It can provide a new approach for tissue functional imaging in vivo, and may have potentials in developing into an appliance for clinic diagnosis.

  8. A proof of the Woodward-Lawson sampling method for a finite linear array

    NASA Technical Reports Server (NTRS)

    Somers, Gary A.

    1993-01-01

    An extension of the continuous aperture Woodward-Lawson sampling theorem has been developed for a finite linear array of equidistant identical elements with arbitrary excitations. It is shown that by sampling the array factor at a finite number of specified points in the far field, the exact array factor over all space can be efficiently reconstructed in closed form. The specified sample points lie in real space and hence are measurable provided that the interelement spacing is greater than approximately one half of a wavelength. This paper provides insight as to why the length parameter used in the sampling formulas for discrete arrays is larger than the physical span of the lattice points in contrast with the continuous aperture case where the length parameter is precisely the physical aperture length.

  9. Microwell Arrays for Studying Many Individual Cells

    NASA Technical Reports Server (NTRS)

    Folch, Albert; Kosar, Turgut Fettah

    2009-01-01

    "Laboratory-on-a-chip" devices that enable the simultaneous culturing and interrogation of many individual living cells have been invented. Each such device includes a silicon nitride-coated silicon chip containing an array of micromachined wells sized so that each well can contain one cell in contact or proximity with a patch clamp or other suitable single-cell-interrogating device. At the bottom of each well is a hole, typically 0.5 m wide, that connects the well with one of many channels in a microfluidic network formed in a layer of poly(dimethylsiloxane) on the underside of the chip. The microfluidic network makes it possible to address wells (and, thus, cells) individually to supply them with selected biochemicals. The microfluidic channels also provide electrical contact to the bottoms of the wells.

  10. Customized homogenization and shaping of LED light by micro cells arrays

    NASA Astrophysics Data System (ADS)

    Asoubar, Daniel; Hellmann, Christian; Schweitzer, Hagen; Kuhn, Michael; Wyrowski, Frank

    2015-03-01

    The energy-efficient use of LED light requires the development of compact illumination systems for the customized homogenization and shaping of partially-coherent LED light. Therefore a design concept which is based on arrays of aperiodic micro structures, namely cells, for primary or secondary optics is introduced. Each cell of the array deflects locally the light into predefined directions and results in a light spot in the target plane. The light spots of all array cells together form the desired light pattern. The performance of three different cell geometries (linear gratings, micro prisms andmicromirrors) on the homogenization and shaping ofmonochromatic as well as white light LEDs is demonstrated. For the realistic evaluation of the illumination system an LED model including power spectrum, polarization, spatial and temporal coherence is chosen. Furthermore wave-optical effects like diffraction at the cell apertures are taken into account. For the grating cells arrays a rigorous analysis of the diffraction efficiencies is included.

  11. Fast photo-acoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yin, Bangzheng; Xing, Da; Yang, Diwu; Tan, Yi; Chen, Qun

    2005-04-01

    Photoacoustic imaging combines the contrast advantage of pure optical imaging and the resolution advantage of pure ultrasonic imaging. It has become a popular research subject at present. A fast photoacoustic imaging system based on multi-element linear transducer array and phase-controlled focus method was developed and tested on phantoms and tissues. A Q switched Nd:YAG laser operating at 532nm was used in our experiment as thermal source. The multi-element linear transducer array consists of 320 elements. By phase-controlled focus method, 64 signals, one of which gathered by 11-group element, make up of an image. Experiment results can map the distribution of the optical absorption correctly. The same transducer array also can operate as a conventional phase array and produced ultrasound imaging. Compared to other existing technology and algorithm, the PA imaging based on transducer array was characterize by speediness and convenience. It can provide a new approach for tissue functional imaging in vivo, and may have potentials in developing into an appliance for clinic diagnosis.

  12. Airborne Linear Array Image Geometric Rectification Method Based on Unequal Segmentation

    NASA Astrophysics Data System (ADS)

    Li, J. M.; Li, C. R.; Zhou, M.; Hu, J.; Yang, C. M.

    2016-06-01

    As the linear array sensor such as multispectral and hyperspectral sensor has great potential in disaster monitoring and geological survey, the quality of the image geometric rectification should be guaranteed. Different from the geometric rectification of airborne planar array images or multi linear array images, exterior orientation elements need to be determined for each scan line of single linear array images. Internal distortion persists after applying GPS/IMU data directly to geometrical rectification. Straight lines may be curving and jagged. Straight line feature -based geometrical rectification algorithm was applied to solve this problem, whereby the exterior orientation elements were fitted by piecewise polynomial and evaluated with the straight line feature as constraint. However, atmospheric turbulence during the flight is unstable, equal piecewise can hardly provide good fitting, resulting in limited precision improvement of geometric rectification or, in a worse case, the iteration cannot converge. To solve this problem, drawing on dynamic programming ideas, unequal segmentation of line feature-based geometric rectification method is developed. The angle elements fitting error is minimized to determine the optimum boundary. Then the exterior orientation elements of each segment are fitted and evaluated with the straight line feature as constraint. The result indicates that the algorithm is effective in improving the precision of geometric rectification.

  13. Determination of S-wave slowness from a linear array of borehole receivers

    NASA Astrophysics Data System (ADS)

    Eisner, Leo; Fischer, Tomáš; Rutledge, James T.

    2009-01-01

    Locations of seismic events from a linear array of receivers may require determination of slowness vectors of arriving waves. In an isotropic medium, P waves are polarized along the slowness vector, which enables direct determination of backazimuth (i.e. azimuth to a source from a receiver) from P-wave polarization. In contrast, S waves usually have much larger signal-to-noise ratio than P waves, but are polarized in a plane perpendicular to their slowness vectors, which prevents direct determination of their backazimuth. We have developed a novel technique to determine the slowness vector of S waves detected in a linear array of receivers in an isotropic medium. We combine the S-wave polarization measurement with the derivative of the S-wave travel times along the array to obtain the full slowness vector and backazimuth. The proposed method allows one to determine direction to sources of seismic events from a single linear array of receivers, using only S waves. This technique is not affected by SV waves, which is shown by a test on a synthetic data set. We also test the method on two real microseismic data sets from hydraulic fracturing treatments and show that it outperforms the backazimuth determination from P waves and from horizontal polarization of S waves.

  14. Linearity Testing of Photovoltaic Cells: Preprint

    SciTech Connect

    Emery, K.; Winter, S.; Pinegar, S.; Nalley D.

    2006-05-01

    Photovoltaic devices are rated in terms of their peak power with respect to a specific spectrum, total irradiance, and temperature. To rate photovoltaic devices, a reference detector is required whose response is linear with total irradiance. This paper describes a procedure to determine the linearity of the short-circuit current (Isc) versus the total irradiance (Etot) by illuminating a reference cell with two lamps. A device is linear if the current measured with both lamps illuminating the cell is the same as the sum of the currents with each lamp illuminating the cell. The two-lamp method is insensitive to the light spectra or spatial nonuniformity changing with irradiance. The two-lamp method is rapid, easy to implement, and does not require operator intervention to change the irradiances. The presence of room light only limits the lowest irradiance that can be evaluated. Unlike other methods, the two-lamp method does not allow the current to be corrected for nonlinear effects.

  15. A Hybrid Particle Swarm with Differential Evolution Operator Approach (DEPSO) for Linear Array Synthesis

    NASA Astrophysics Data System (ADS)

    Sarkar, Soham; Das, Swagatam

    In recent years particle swarm optimization emerges as one of the most efficient global optimization tools. In this paper, a hybrid particle swarm with differential evolution operator, termed DEPSO, is applied for the synthesis of linear array geometry. Here, the minimum side lobe level and null control, both are obtained by optimizing the spacing between the array elements by this technique. Moreover, a statistical comparison is also provided to establish its performance against the results obtained by Genetic Algorithm (GA), classical Particle Swarm Optimization (PSO), Tabu Search Algorithm (TSA), Differential Evolution (DE) and Memetic Algorithm (MA).

  16. Sensitivity of linear CCD array based film scanners used for film dosimetry.

    PubMed

    Devic, Slobodan; Wang, Yi-Zhen; Tomic, Nada; Podgorsak, Ervin B

    2006-11-01

    Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films. PMID:17153378

  17. Sensitivity of linear CCD array based film scanners used for film dosimetry

    SciTech Connect

    Devic, Slobodan; Wang Yizhen; Tomic, Nada; Podgorsak, Ervin B.

    2006-11-15

    Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films.

  18. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Horchani, R.

    2016-02-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

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

    PubMed

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

    2016-01-01

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

  20. Linear laser diode arrays for improvement in optical disk recording for space stations

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The design and fabrication of individually addressable laser diode arrays for high performance magneto-optic recording systems are presented. Ten diode arrays with 30 mW cW light output, linear light vs. current characteristics and single longitudinal mode spectrum were fabricated using channel substrate planar (CSP) structures. Preliminary results on the inverse CSP structure, whose fabrication is less critically dependent on device parameters than the CSP, are also presented. The impact of systems parameters and requirements, in particular, the effect of feedback on laser design is assessed, and techniques to reduce feedback or minimize its effect on systems performance, including mode-stabilized structures, are evaluated.

  1. Acoustic contrast control in an arc-shaped area using a linear loudspeaker array.

    PubMed

    Zhao, Sipei; Qiu, Xiaojun; Burnett, Ian

    2015-02-01

    This paper proposes a method of creating acoustic contrast control in an arc-shaped area using a linear loudspeaker array. The boundary of the arc-shaped area is treated as the envelope of the tangent lines that can be formed by manipulating the phase profile of the loudspeakers in the array. When compared with the existing acoustic contrast control method, the proposed method is able to generate sound field inside an arc-shaped area and achieve a trade-off between acoustic uniformity and acoustic contrast. The acoustic contrast created by the proposed method increases while the acoustic uniformity decreases with frequency. PMID:25698035

  2. Reproduction of a higher-order circular harmonic field using a linear array of loudspeakers.

    PubMed

    Lee, Jung-Min; Choi, Jung-Woo; Kim, Yang-Hann

    2015-03-01

    This paper presents a direct formula for reproducing a sound field consisting of higher-order circular harmonics with polar phase variation. Sound fields with phase variation can be used for synthesizing various spatial attributes, such as the perceived width or the location of a virtual sound source. To reproduce such a sound field using a linear loudspeaker array, the driving function of the array is derived in the format of an integral formula. The proposed function shows fewer reproduction errors than a conventional formula focused on magnitude variations. In addition, analysis of the sweet spot reveals that its shape can be asymmetric, depending on the order of harmonics. PMID:25951623

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

    PubMed Central

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

    2016-01-01

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

  4. Collective Interaction in a Linear Array of Supersonic Rectangular Jets: A Linear Spatial Instability Study

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1999-01-01

    A linear spatial instability model for multiple spatially periodic supersonic rectangular jets is solved using Floquet-Bloch theory. It is assumed that in the region of interest a coherent wave can propagate. For the case studied large spatial growth rates are found. This work is motivated by an increase in mixing found in experimental measurements of spatially periodic supersonic rectangular jets with phase-locked screech and edge tone feedback locked subsonic jets. The results obtained in this paper suggests that phase-locked screech or edge tones may produce correlated spatially periodic jet flow downstream of the nozzles which creates a large span wise multi-nozzle region where a coherent wave can propagate. The large spatial growth rates for eddies obtained by model calculation herein are related to the increased mixing since eddies are the primary mechanism that transfer energy from the mean flow to the large turbulent structures. Calculations of spacial growth rates will be presented for a set of relative Mach numbers and spacings for which experimental measurements have been made. Calculations of spatial growth rates are presented for relative Mach numbers from 1.25 to 1.75 with ratios of nozzle spacing to nozzle width ratios from s/w(sub N) = 4 to s/w(sub N) = 13.7. The model may be of significant scientific and engineering value in the quest to understand and construct supersonic mixer-ejector nozzles which provide increased mixing and reduced noise.

  5. Annular Arrays Of Solar Cells For Spinning Spacecraft

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1995-01-01

    Report proposes annular arrays of solar photovoltaic cells installed on spin-stabilized spacecraft. Annular array faces Sun. Typical array consists of two stacked annuli of solar cells: one annulus fixed about spin axis, while other divided into deployable sectors mounted on dual swing arms and stowed by folding them atop fixed annulus. Once released, deployable sectors swing outward under spring or centrifugal force and expose fixed array so it generates additional power.

  6. Particle velocity gradient based acoustic mode beamforming for short linear vector sensor arrays.

    PubMed

    Gur, Berke

    2014-06-01

    In this paper, a subtractive beamforming algorithm for short linear arrays of two-dimensional particle velocity sensors is described. The proposed method extracts the highly directional acoustic modes from the spatial gradients of the particle velocity field measured at closely spaced sensors along the array. The number of sensors in the array limits the highest order of modes that can be extracted. Theoretical analysis and numerical simulations indicate that the acoustic mode beamformer achieves directivity comparable to the maximum directivity that can be obtained with differential microphone arrays of equivalent aperture. When compared to conventional delay-and-sum beamformers for pressure sensor arrays, the proposed method achieves comparable directivity with 70%-85% shorter apertures. Moreover, the proposed method has additional capabilities such as high front-back (port-starboard) discrimination, frequency and steer direction independent response, and robustness to correlated ambient noise. Small inter-sensor spacing that results in very compact apertures makes the proposed beamformer suitable for space constrained applications such as hearing aids and short towed arrays for autonomous underwater platforms. PMID:24907810

  7. Liquid cooled, linear focus solar cell receiver

    DOEpatents

    Kirpich, Aaron S.

    1985-01-01

    Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

  8. Liquid cooled, linear focus solar cell receiver

    DOEpatents

    Kirpich, A.S.

    1983-12-08

    Separate structures for electrical insulation and thermal conduction are established within a liquid cooled, linear focus solar cell receiver for use with parabolic or Fresnel optical concentrators. The receiver includes a V-shaped aluminum extrusion having a pair of outer faces each formed with a channel receiving a string of solar cells in thermal contact with the extrusion. Each cell string is attached to a continuous glass cover secured within the channel with spring clips to isolate the string from the external environment. Repair or replacement of solar cells is effected simply by detaching the spring clips to remove the cover/cell assembly without interrupting circulation of coolant fluid through the receiver. The lower surface of the channel in thermal contact with the cells of the string is anodized to establish a suitable standoff voltage capability between the cells and the extrusion. Primary electrical insulation is provided by a dielectric tape disposed between the coolant tube and extrusion. Adjacent solar cells are soldered to interconnect members designed to accommodate thermal expansion and mismatches. The coolant tube is clamped into the extrusion channel with a releasably attachable clamping strip to facilitate easy removal of the receiver from the coolant circuit.

  9. Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

    PubMed

    Hansen, Lajla Bruntse; Buus, Soren; Schafer-Nielsen, Claus

    2013-01-01

    We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2). Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA) as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids) at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA) and from rabbit serum albumin (RSA) were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level. PMID:23894373

  10. Array error calibration methods in downward-looking linear-array three-dimensional synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Tan, Weixian; Huang, Pingping; Han, Kuoye; Liu, Qi; Peng, Xueming

    2016-04-01

    In order to achieve high-precision three-dimensional (3-D) imaging with an airborne downward-looking linear-array 3-D synthetic aperture radar (LA-3D-SAR), a uniform virtual antenna array can be obtained by aperture synthesis of the cross-track sparse multiple-input-multiple-output array. However, the actual 3-D imaging quality is unavoidably degraded by array errors such as the multichannel amplitude-phase errors due to the nonideal antenna characteristics, and the virtual element position errors due to vibrations and motion measurement deviations. We investigate the effects of these errors on the forms and the degrees of image quality degradation and consider the use of corresponding calibration methods to eliminate the effects of errors. For the multichannel amplitude-phase errors, the target response is subject to an integrated sidelobe level increase introduced by the phase error, which can be calibrated based on external (parallel or point target) calibrators, as proposed in the paper. For the virtual element position errors, they mainly the result of contrast degradation and noise in the image along the cross-track direction and have little impact on the range and along-track directions. The imaging performance is more sensitive to the error component in the height direction as compared to other components, the precision requirement of which should be established as the calibration reference. A calibration method based on time-divided active calibrators is proposed to estimate and correct the virtual element position errors. Both numerical simulations and real data experiments have shown the validity of the analyses as well as the effectiveness of the proposed calibration methods.

  11. Design of 45-degree Linearly Polarized Substrate Integrated Waveguide-fed Slot Array Antennas

    NASA Astrophysics Data System (ADS)

    Zhang, Qingfeng; Lu, Yilong

    2008-11-01

    This paper presents a method of designing substrate integrated waveguide-fed (SIW-fed) slot array antennas. The design theory is based on the circuit model of slot and via as well as the reflection canceling. To prove the feasibility of this method, a 10-element K-band SIW-fed 45-degree linearly polarized slot array antenna with uniform power distribution is designed. By full-wave simulation, the antenna has a good impedance bandwidth of 7.5% and uniform power distribution. Besides, a maximum gain of 15.3dBi is obtained in the broadside and the cross polarization is suppressed below -23.5dB in the boresight. This type of SIW-fed slot array antennas can be a good candidate for microwave and millimeter-wave applications, especially for auto-motive collision-avoidance radar systems.

  12. Studies of optical and biological properties of terrestrial land cover using multispectral linear array technology

    NASA Technical Reports Server (NTRS)

    Barnes, W. L.; Salomonson, V. V.

    1984-01-01

    A series of experiments to study the optical and biological properties of terrestrial land cover are planned for late 1987 using a six-channel imaging spectroradiometer based on newly developed multispectral linear array (MLA) detector technology. Data from selected portions of the Sahel and rain forests of Africa and South America will be used to delineate biomass classes and estimate spherical albedos. A spatial resolution of 15 meters in the four visible-near IR channels and 30 meters in two shortwave IR channels, including a 'new' channel centered at 1.24 micrometers when combined with a spectral width of 20 nm for all channels, will be used to investigate possible improvements in land cover classification. Technology demonstrations include a test of data compression on data quality, the first spaceborne utilization of short wave infrared Schottky barrier Pd2Si detector arrays, and the use of close-butted, multi-array modules with attached spectral filters.

  13. 250 kA compact linear transformer driver for wire array z-pinch loads

    NASA Astrophysics Data System (ADS)

    Bott, S. C.; Haas, D. M.; Madden, R. E.; Ueda, U.; Eshaq, Y.; Collins, G., IV; Gunasekera, K.; Mariscal, D.; Peebles, J.; Beg, F. N.; Mazarakis, M.; Struve, K.; Sharpe, R.

    2011-05-01

    We present the application of a short rise (˜150ns) 250 kA linear transformer driver (LTD) to wire array z-pinch loads for the first time. The generator is a modification of a previous driver in which a new conical power feed provides a low inductance coupling to wire loads. Performance of the new design using both short circuit and plasma loads is presented and discussed. The final design delivers ˜200kA to a wire array load which is in good agreement with SCREAMER calculations using a simplified representative circuit. Example results demonstrate successful experiments using cylindrical, conical, and inverse wire arrays as well as previously published work on x-pinch loads.

  14. Linearly polarized light emission from quantum dots with plasmonic nanoantenna arrays.

    PubMed

    Ren, Mengxin; Chen, Mo; Wu, Wei; Zhang, Lihui; Liu, Junku; Pi, Biao; Zhang, Xinzheng; Li, Qunqing; Fan, Shoushan; Xu, Jingjun

    2015-05-13

    Polarizers provide convenience in generating polarized light, meanwhile their adoption raises problems of extra weight, cost, and energy loss. Aiming to realize polarizer-free polarized light sources, herein, we present a plasmonic approach to achieve direct generation of linearly polarized optical waves at the nanometer scale. Periodic slot nanoantenna arrays are fabricated, which are driven by the transition dipole moments of luminescent semiconductor quantum dots. By harnessing interactions between quantum dots and scattered fields from the nanoantennas, spontaneous emission with a high degree of linear polarization is achieved from such hybrid antenna system with polarization perpendicular to antenna slot. We also demonstrate that the polarization is engineerable in aspects of both spectrum and magnitude by tailoring plasmonic resonance of the antenna arrays. Our findings will establish a basis for the development of innovative polarized light-emitting devices, which are useful in optical displays, spectroscopic techniques, optical telecommunications, and so forth. PMID:25877386

  15. Covariance analysis and phase ambiguity resolution for a linear interferometer antenna array

    NASA Astrophysics Data System (ADS)

    Johnson, James Andrew

    This thesis explores the application of mathematical techniques for estimating the angle of arrival (AOA) using a receiving platform having a linear interferometer antenna array. It addresses the estimation accuracy of interferometer phase measurements of a signal with superposed Gaussian noise from multiple antenna baselines, and provides a method for resolving the modulo two-pi problem inherent to many phase measurement systems. The study extends prior theoretical work (Hanna, C., 1983) by laying a mathematical foundation to complement his geometrical approach, provides a robust method of performance prediction for such a system. Key elements include estimation accuracy of a signal parameter with additive noise; the design of the linear antenna array element spacings and the relationship to Diophantine equations; and the application of the Cramer-Rao lower bound on variance of parameter estimation. It is hoped that the work presented here will serve as a practical guide for research scientists and engineers.

  16. Steering vector sensor array elements with linear cardioids and nonlinear hippioids.

    PubMed

    Smith, Kevin B; van Leijen, A Vincent

    2007-07-01

    The purpose of this work is to study the impact due to individual vector sensor element steering patterns on linear array beamforming. Standard, linear beamformers employ cardioid beampatterns for each vector sensor. In this work, a class of vector sensor element steering patterns beyond the standard cardioid was examined. The element weighting is nonlinear but nonadaptive, making it simple to implement in hardware processing. The new sensor steering patterns, referred to as hippioids, are products of cardioids and various powers of hippopedes. The angular resolution of individual sensors, the impact on angular resolution from arrays of varying aperture, and peak-to-sidelobe levels will serve as performance measures. An example of the differences in vector sensor steering patterns is provided using measured directional frequency and recorded buoy data. PMID:17614496

  17. Production of Energetic Active-Oxygen Species at Atmospheric Pressure by Linear Microplasma Arrays

    NASA Astrophysics Data System (ADS)

    Rawlins, Wilson; Galbally-Kinney, Kristin; Davis, Steven; Hoskinson, Alan; Hopwood, Jeffrey

    2014-10-01

    Linear arrays of stripline resonators operated at microwave frequencies and low powers provide spatially and temporally continuous micro-discharges with high E/N at atmospheric pressure. When implemented in a discharge-flow reactor, these microplasmas excite metastable singlet molecular oxygen and dissociate oxygen molecules to produce atomic oxygen, with efficiencies comparable to conventional microwave resonant cavities at low pressures. At elevated pressure, production of atomic oxygen leads to prompt formation of ozone immediately downstream of the discharge exit. We have observed and quantified the production of O2(a 1 Δ) metastables and O3 in the effluent of linear microplasma arrays for O2/He, O2/Ar, O2/N2/He,andO2/N2/Ar mixtures as functions of pressure, gas flow rate, and species mixing ratio. We compare results for single-array microplasmas, where the discharge products are formed in a small volume and entrained into the bulk flow, and overlapping dual-array microplasmas which process larger gas flow volumes. Supported by the Air Force Research Laboratory and Department of Energy.

  18. Broadband ultrasonic linear array using ternary PIN-PMN-PT single crystal.

    PubMed

    Wang, Wei; Zhao, Xiangyong; Or, Siu Wing; Leung, Chung Ming; Zhang, Yaoyao; Jiao, Jie; Luo, Haosu

    2012-09-01

    Ternary Pb(In(1/2)Nb(1/2))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) single crystal was investigated for potential application in ultrasonic linear array. Orientation and temperature dependences of height extensional electromechanical coupling coefficient k'(33) for PIN-PMN-PT single crystal were studied. It was found that the [001] poled PIN-PMN-PT diced along the [100] direction would achieve a maximum k'(33) (~87%) and the service temperature was up to 110 °C. Ultrasonic linear arrays using PIN-PMN-PT single crystal and PZT ceramic were fabricated and compared. The bandwidth at -6 dB, two-way insertion loss and pulse length of the PIN-PMN-PT array were 98.6%, -45.1 dB, and 0.28 μs, respectively, which were about 25% broader, 3.7dB higher, and 0.08 μs shorter than those of the PZT array. The experimental results agreed well with the theoretical simulation. These superior performances were attributable to the excellent piezoelectric properties of PIN-PMN-PT single crystal. PMID:23020406

  19. Broadband implementation of coprime linear microphone arrays for direction of arrival estimation.

    PubMed

    Bush, Dane; Xiang, Ning

    2015-07-01

    Coprime arrays represent a form of sparse sensing which can achieve narrow beams using relatively few elements, exceeding the spatial Nyquist sampling limit. The purpose of this paper is to expand on and experimentally validate coprime array theory in an acoustic implementation. Two nested sparse uniform linear subarrays with coprime number of elements ( M and N) each produce grating lobes that overlap with one another completely in just one direction. When the subarray outputs are combined it is possible to retain the shared beam while mostly canceling the other superfluous grating lobes. In this way a small number of microphones ( N+M-1) creates a narrow beam at higher frequencies, comparable to a densely populated uniform linear array of MN microphones. In this work beampatterns are simulated for a range of single frequencies, as well as bands of frequencies. Narrowband experimental beampatterns are shown to correspond with simulated results even at frequencies other than the arrays design frequency. Narrowband side lobe locations are shown to correspond to the theoretical values. Side lobes in the directional pattern are mitigated by increasing bandwidth of analyzed signals. Direction of arrival estimation is also implemented for two simultaneous noise sources in a free field condition. PMID:26233043

  20. Ceramic scintillator-coupled linear array PIN photodiode for X-ray scanner

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Hyun; Kang, Dong-Wan; Cho, Gyuseong; Kim, Do Kyung

    2007-08-01

    In order to design the full system of dual-energy X-ray scanner, each component of the system has been fabricated and tested. The high-energy X-ray detector modules used a ceramic scintillator of Eu 3+-doped (Gd,Y) 2O 3, manufactured using Glycine Nitrate Process (GNP). This was coupled to a 16-channel linear array PIN-type photodiode. The low-energy module was a commercially available Lanex Regular screen that was also coupled to a 16-channel linear array PIN-type photodiode. The 16-channel linear array PIN-type photodiode of 1.5 mm×3.2 mm was fabricated in the process of Electronics and Telecommunications Research Institute (ETRI). With a data acquisition system, signal-to-noise ratio was measured at low X-ray energy and low photon flux to evaluate each scintillator-coupled detector module. Through the experiment results and analysis, we inspected each component of the system as a dual-energy single-exposure X-ray scanner.

  1. 256×1 element linear InGaAs short wavelength near-infrared detector arrays

    NASA Astrophysics Data System (ADS)

    Li, Xue; Tang, Hengjing; Fan, Guangyu; Liu, Dafu; Shao, Xiumei; Zhang, Yonggang; Zhang, Haiyan; Chen, Xinyu; Zhu, Sangen; Gong, Haimei; Fang, Jiaxiong

    2008-03-01

    256×1 element linear InGaAs detector arrays assembly have been fabricated for the short wave infrared band(0.9~1.7μm), including the detector, CMOS readout circuits, thermoelectric cooler in a sealed package. The InGaAs detectors were achieved by mesa structure on the p-InP/i-InGaAs/n-InP double hetero-structure epitaxial material. 256×1 element linear InGaAs detectors were wire-bonded to 128×1 element odd and even ROIC, which were packaged in a dual-in-line package by parallel sealing. The characteristics of detectors and detector arrays module were investigated at the room temperature. The detector shows response peak at 1.62μm with 50% cutoff wavelength of 1.73μm and average R0A with 5.02KΩ•cm2. Response non-uniformity and average peak detectivity of 256×1 element linear InGaAs detector arrays are 3.10% and 1.38×10 12cmHz 1/2/W, respectively.

  2. Correction of linear-array lidar intensity data using an optimal beam shaping approach

    NASA Astrophysics Data System (ADS)

    Xu, Fan; Wang, Yuanqing; Yang, Xingyu; Zhang, Bingqing; Li, Fenfang

    2016-08-01

    The linear-array lidar has been recently developed and applied for its superiority of vertically non-scanning, large field of view, high sensitivity and high precision. The beam shaper is the key component for the linear-array detection. However, the traditional beam shaping approaches can hardly satisfy our requirement for obtaining unbiased and complete backscattered intensity data. The required beam distribution should roughly be oblate U-shaped rather than Gaussian or uniform. Thus, an optimal beam shaping approach is proposed in this paper. By employing a pair of conical lenses and a cylindrical lens behind the beam expander, the expanded Gaussian laser was shaped to a line-shaped beam whose intensity distribution is more consistent with the required distribution. To provide a better fit to the requirement, off-axis method is adopted. The design of the optimal beam shaping module is mathematically explained and the experimental verification of the module performance is also presented in this paper. The experimental results indicate that the optimal beam shaping approach can effectively correct the intensity image and provide ~30% gain of detection area over traditional approach, thus improving the imaging quality of linear-array lidar.

  3. The performance of bridge-linked solar cell arrays

    NASA Astrophysics Data System (ADS)

    Brandstetter, A.; Hinds, A.; Inall, E. K.

    Bridge-linked solar cell arrays (BLA) consist of a repeating mesh of four cells connected as is in a bridge rectifier. Calculations and measurements were made to compare the performance of these and series-parallel arrays (SPA). The arraying power loss for typical cells was 1 percent in a BLA and 2 percent in SPA. A shadow one cell wide and 12 long diagonally across the array halved the output of the SPA but dropped the BLA by only 7 percent, and with the array short-circuited the reverse voltages across the shaded cells in the BLA were a third of those for the SPA. A shadow right across any loaded array will cut the output and cause high reverse voltages. Diodes across blocks must be used, even with a BLA, to protect the cells under these conditions.

  4. Cell surface lectin array: parameters affecting cell glycan signature.

    PubMed

    Landemarre, Ludovic; Cancellieri, Perrine; Duverger, Eric

    2013-04-01

    Among the "omics", glycomics is one of the most complex fields and needs complementary strategies of analysis to decipher the "glycan dictionary". As an alternative method, which has developed since the beginning of the 21st century, lectin array technology could generate relevant information related to glycan motifs, accessibility and a number of other valuable insights from molecules (purified and non-purified) or cells. Based on a cell line model, this study deals with the key parameters that influence the whole cell surface glycan interaction with lectin arrays and the consequences on the interpretation and reliability of the results. The comparison between the adherent and suspension forms of Chinese Hamster Ovary (CHO) cells, showed respective glycan signatures, which could be inhibited specifically by neoglycoproteins. The modifications of the respective glycan signatures were also revealed according to the detachment modes and cell growth conditions. Finally the power of lectin array technology was highlighted by the possibility of selecting and characterizing a specific clone from the mother cell line, based on the slight difference determination in the respective glycan signatures. PMID:22899543

  5. 3D imaging LADAR with linear array devices: laser, detector and ROIC

    NASA Astrophysics Data System (ADS)

    Kameyama, Shumpei; Imaki, Masaharu; Tamagawa, Yasuhisa; Akino, Yosuke; Hirai, Akihito; Ishimura, Eitaro; Hirano, Yoshihito

    2009-07-01

    This paper introduces the recent development of 3D imaging LADAR (LAser Detection And Ranging) in Mitsubishi Electric Corporation. The system consists of in-house-made key devices which are linear array: the laser, the detector and the ROIC (Read-Out Integrated Circuit). The laser transmitter is the high power and compact planar waveguide array laser at the wavelength of 1.5 micron. The detector array consists of the low excess noise Avalanche Photo Diode (APD) using the InAlAs multiplication layer. The analog ROIC array, which is fabricated in the SiGe- BiCMOS process, includes the Trans-Impedance Amplifiers (TIA), the peak intensity detectors, the Time-Of-Flight (TOF) detectors, and the multiplexers for read-out. This device has the feature in its detection ability for the small signal by optimizing the peak intensity detection circuit. By combining these devices with the one dimensional fast scanner, the real-time 3D range image can be obtained. After the explanations about the key devices, some 3D imaging results are demonstrated using the single element key devices. The imaging using the developed array devices is planned in the near future.

  6. Equivalent circuit-based analysis of CMUT cell dynamics in arrays.

    PubMed

    Oguz, H K; Atalar, Abdullah; Köymen, Hayrettin

    2013-05-01

    Capacitive micromachined ultrasonic transducers (CMUTs) are usually composed of large arrays of closely packed cells. In this work, we use an equivalent circuit model to analyze CMUT arrays with multiple cells. We study the effects of mutual acoustic interactions through the immersion medium caused by the pressure field generated by each cell acting upon the others. To do this, all the cells in the array are coupled through a radiation impedance matrix at their acoustic terminals. An accurate approximation for the mutual radiation impedance is defined between two circular cells, which can be used in large arrays to reduce computational complexity. Hence, a performance analysis of CMUT arrays can be accurately done with a circuit simulator. By using the proposed model, one can very rapidly obtain the linear frequency and nonlinear transient responses of arrays with an arbitrary number of CMUT cells. We performed several finite element method (FEM) simulations for arrays with small numbers of cells and showed that the results are very similar to those obtained by the equivalent circuit model. PMID:23661137

  7. Experimental validation of a coprime linear microphone array for high-resolution direction-of-arrival measurements.

    PubMed

    Xiang, Ning; Bush, Dane; Summers, Jason E

    2015-04-01

    Coprime linear microphone arrays allow for narrower beams with fewer sensors. A coprime microphone array consists of two staggered uniform linear subarrays with M and N microphones, where M and N are coprime with each other. By applying spatial filtering to both subarrays and combining their outputs, M+N-1 microphones yield M⋅N directional bands. In this work, the coprime sampling theory is implemented in the form of a linear microphone array of 16 elements with coprime numbers of 9 and 8. This coprime microphone array is experimentally tested to validate the coprime array theory. Both predicted and measured results are discussed. Experimental results confirm that narrow beampatterns as predicted by the coprime sampling theory can be obtained by the coprime microphone array. PMID:25920875

  8. 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.

  9. Non linear behaviour of cell tensegrity models

    NASA Astrophysics Data System (ADS)

    Alippi, A.; Bettucci, A.; Biagioni, A.; Conclusio, D.; D'Orazio, A.; Germano, M.; Passeri, D.

    2012-05-01

    Tensegrity models for the cytoskeleton structure of living cells is largely used nowadays for interpreting the biochemical response of living tissues to mechanical stresses. Microtubules, microfilaments and filaments are the microscopic cell counterparts of struts (microtubules) and cables (microfilaments and filaments) in the macroscopic world: the formers oppose to compression, the latters to tension, thus yielding an overall structure, light and highly deformable. Specific cell surface receptors, such as integrins, act as the coupling elements that transmit the outside mechanical stress state into the cell body. Reversible finite deformations of tensegrity structures have been widely demonstrated experimentally and in a number of living cell simulations. In the present paper, the bistability behaviour of two general models, the linear bar oscillator and the icosahedron, is studied, as they are both obtained from mathematical simulation, the former, and from larger scale experiments, the latter. The discontinuity in the frequency response of the oscillation amplitude and the lateral bending of the resonance curves are put in evidence, as it grows larger as the driving amplitude increases, respectively.

  10. Super non-linear RRAM with ultra-low power for 3D vertical nano-crossbar arrays.

    PubMed

    Luo, Qing; Xu, Xiaoxin; Liu, Hongtao; Lv, Hangbing; Gong, Tiancheng; Long, Shibing; Liu, Qi; Sun, Haitao; Banerjee, Writam; Li, Ling; Gao, Jianfeng; Lu, Nianduan; Liu, Ming

    2016-08-25

    Vertical crossbar arrays provide a cost-effective approach for high density three-dimensional (3D) integration of resistive random access memory. However, an individual selector device is not allowed to be integrated with the memory cell separately. The development of V-RRAM has impeded the lack of satisfactory self-selective cells. In this study, we have developed a high performance bilayer self-selective device using HfO2 as the memory switching layer and a mixed ionic and electron conductor as the selective layer. The device exhibits high non-linearity (>10(3)) and ultra-low half-select leakage (<0.1 pA). A four layer vertical crossbar array was successfully demonstrated based on the developed self-selective device. High uniformity, ultra-low leakage, sub-nA operation, self-compliance, and excellent read/write disturbance immunity were achieved. The robust array level performance shows attractive potential for low power and high density 3D data storage applications. PMID:27510434

  11. Comparison of Hybribio GenoArray and Roche human papillomavirus (HPV) linear array for HPV genotyping in anal swab samples.

    PubMed

    Low, Huey Chi; Silver, Michelle I; Brown, Brandon J; Leng, Chan Yoon; Blas, Magaly M; Gravitt, Patti E; Woo, Yin Ling

    2015-02-01

    Human papillomavirus (HPV) is causally associated with anal cancer, as HPV DNA is detected in up to 90% of anal intraepithelial neoplasias and anal cancers. With the gradual increase of anal cancer rates, there is a growing need to establish reliable and clinically relevant methods to detect anal cancer precursors. In resource-limited settings, HPV DNA detection is a potentially relevant tool for anal cancer screening. Here, we evaluated the performance of the Hybribio GenoArray (GA) for genotyping HPV in anal samples, against the reference standard Roche Linear Array (LA). Anal swab samples were obtained from sexually active men who have sex with men. Following DNA extraction, each sample was genotyped using GA and LA. The overall interassay agreement, type-specific, and single and multiple genotype agreements were evaluated by kappa statistics and McNemar's χ(2) tests. Using GA and LA, 68% and 76% of samples were HPV DNA positive, respectively. There was substantial interassay agreements for the detection of all HPV genotypes (κ = 0.70, 86% agreement). Although LA was able to detect more genotypes per sample, the interassay agreement was acceptable (κ = 0.53, 63% agreement). GA had poorer specific detection of HPV genotypes 35, 42, and 51 (κ < 0.60). In conclusion, GA and LA showed good interassay agreement for the detection of most HPV genotypes in anal samples. However, the detection of HPV DNA in up to 76% of anal samples warrants further evaluation of its clinical significance. PMID:25502520

  12. Comparison of Hybribio GenoArray and Roche Human Papillomavirus (HPV) Linear Array for HPV Genotyping in Anal Swab Samples

    PubMed Central

    Silver, Michelle I.; Brown, Brandon J.; Leng, Chan Yoon; Blas, Magaly M.; Gravitt, Patti E.; Woo, Yin Ling

    2014-01-01

    Human papillomavirus (HPV) is causally associated with anal cancer, as HPV DNA is detected in up to 90% of anal intraepithelial neoplasias and anal cancers. With the gradual increase of anal cancer rates, there is a growing need to establish reliable and clinically relevant methods to detect anal cancer precursors. In resource-limited settings, HPV DNA detection is a potentially relevant tool for anal cancer screening. Here, we evaluated the performance of the Hybribio GenoArray (GA) for genotyping HPV in anal samples, against the reference standard Roche Linear Array (LA). Anal swab samples were obtained from sexually active men who have sex with men. Following DNA extraction, each sample was genotyped using GA and LA. The overall interassay agreement, type-specific, and single and multiple genotype agreements were evaluated by kappa statistics and McNemar's χ2 tests. Using GA and LA, 68% and 76% of samples were HPV DNA positive, respectively. There was substantial interassay agreements for the detection of all HPV genotypes (κ = 0.70, 86% agreement). Although LA was able to detect more genotypes per sample, the interassay agreement was acceptable (κ = 0.53, 63% agreement). GA had poorer specific detection of HPV genotypes 35, 42, and 51 (κ < 0.60). In conclusion, GA and LA showed good interassay agreement for the detection of most HPV genotypes in anal samples. However, the detection of HPV DNA in up to 76% of anal samples warrants further evaluation of its clinical significance. PMID:25502520

  13. Radial pn Junction, Wire Array Solar Cells

    NASA Astrophysics Data System (ADS)

    Kayes, Brendan Melville

    Radial pn junctions are potentially of interest in photovoltaics as a way to decouple light absorption from minority carrier collection. In a traditional planar design these occur in the same dimension, and this sets a lower limit on absorber material quality, as cells must both be thick enough to effectively absorb the solar spectrum while also having minority-carrier diffusion lengths long enough to allow for efficient collection of the photo-generated carriers. Therefore, highly efficient photovoltaic devices currently require highly pure materials and expensive processing techniques, while low cost devices generally operate at relatively low efficiency. The radial pn junction design sets the direction of light absorption perpendicular to the direction of minority-carrier transport, allowing the cell to be thick enough for effective light absorption, while also providing a short pathway for carrier collection. This is achieved by increasing the junction area, in order to decrease the path length any photogenerated minority carrier must travel, to be less than its minority carrier diffusion length. Realizing this geometry in an array of semiconducting wires, by for example depositing a single-crystalline inorganic semiconducting absorber layer at high deposition rates from the gas phase by the vapor-liquid-solid (VLS) mechanism, allows for a "bottom up" approach to device fabrication, which can in principle dramatically reduce the materials costs associated with a cell.

  14. Position measurement method based on linear-array CCD with inverting prism

    NASA Astrophysics Data System (ADS)

    Meng, Xiao; Liu, Xiangdong; Xu, Wei

    2005-01-01

    Position measurement in 2D plane plays an important role in many fields such as production controlling, automatic aiming , multimedia, and so on. The application of planar array CCD in 2D position measurement is facile. But it is difficult if both cost and precision to be taken into account. This paper proposed a method realizing 2D position measurement using linear array CCD to solve this problem. A special optical system is designed, including a main lens, an inverting prism, and a combination of a spherical lens and a cylindrical lens, by which the spots equidistant from the basic shaft(eg. x shaft) can be imaged into the same line. With a linear array CCD normal to the axis of the cylinder, the distance from the line to the basic shaft is measured, through which one value of the coordinate(eg. y) can be computed according to the object-to-image conjugate relationship. An inverting prism, eg. DOVE prism, rotating at a palstance of ω followed by the image at 2ω,makes it possible to measure each value of 2D coordinate when the DOVE is in the initial point or turns to 45°(image turns to 90°). A possible application is also given.

  15. Small pitch fringe projection method with multiple linear fiber arrays for 3D shape measurement

    NASA Astrophysics Data System (ADS)

    Hayashi, Takumi; Fujigaki, Motoharu; Murata, Yorinobu

    2014-07-01

    3-D shape measurement systems by contactless method are required in the quality inspections of metal molds and electronic parts in industrial fields. A grating projection method with phase-shifting method has advantages of high precision and high speed. Recently, the size of a BGA (ball grid array) becomes smaller. So the pitch of a grating pattern projected onto the specimen should be smaller. In conventional method, fringe pattern is projected using an imaging lens. The focal depth becomes smaller in the case of reduced projection. It is therefore difficult to project a grating pattern with small pitch onto an object with large incident angles. Authors recently proposed a light source stepping method using a linear LED device. It is easy to shrink the projected grating pitch with a lens because this projection method does not use an imaging lens. The pitch of the projected grating depends on the width of the light source. There is a limit to shrink the projected grating pitch according to the size of the LED chip. In this paper, a small pitch fringe projection method with multiple linear fiber arrays for 3D shape measurement is proposed. The width of the fiber array is 30μm. It is one digit smaller than the width of the LED chip. The experimental result of 3-D shape measurement with small pitch projection with large incident angles is shown.

  16. Highly efficient single cell arraying by integrating acoustophoretic cell pre-concentration and dielectrophoretic cell trapping.

    PubMed

    Kim, Soo Hyeon; Antfolk, Maria; Kobayashi, Marina; Kaneda, Shohei; Laurell, Thomas; Fujii, Teruo

    2015-11-21

    To array rare cells at the single-cell level, the volumetric throughput may become a bottleneck in the cell trapping and the subsequent single-cell analysis, since the target cells per definition commonly exist in a large sample volume after purification from the original sample. Here, we present a novel approach for high throughput single cell arraying by integrating two original microfluidic devices: an acoustofluidic chip and an electroactive microwell array. The velocity of the cells is geared down in the acoustofluidic chip while maintaining a high volume flow rate at the inlet of the microsystem, and the cells are subsequently trapped one by one into the microwell array using dielectrophoresis. The integrated system exhibited a 10 times improved sample throughput compared to trapping with the electroactive microwell array chip alone, while maintaining a highly efficient cell recovery above 90%. The results indicate that the serial integration of the acoustophoretic pre-concentration with the dielectrophoretic cell trapping drastically improves the performance of the electroactive microwell array for highly efficient single cell analysis. This simple and effective system for high throughput single cell arraying with further possible integration of additional functions, including cell sorting and downstream analysis after cell trapping, has potential for development to a highly integrated and automated platform for single-cell analysis of rare cells. PMID:26439940

  17. Mixed Linear/Square-Root Encoded Single Slope Ramp Provides a Fast, Low Noise Analog to Digital Converter with Very High Linearity for Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Wrigley, Christopher James (Inventor); Hancock, Bruce R. (Inventor); Newton, Kenneth W. (Inventor); Cunningham, Thomas J. (Inventor)

    2014-01-01

    An analog-to-digital converter (ADC) converts pixel voltages from a CMOS image into a digital output. A voltage ramp generator generates a voltage ramp that has a linear first portion and a non-linear second portion. A digital output generator generates a digital output based on the voltage ramp, the pixel voltages, and comparator output from an array of comparators that compare the voltage ramp to the pixel voltages. A return lookup table linearizes the digital output values.

  18. Angle resolution of wideband signals received by two slightly diverse linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Bagdasaryan, S. T.; Zinevich, Y. P.

    1984-05-01

    The problem of angle resolution is considered in the case of detection of wideband signals by means of antenna arrays with a discontinuous aperture. The receiver antenna is assumed to be linear and to consist of two separate equidistant arrays of weakly directional elements. The signals are assumed to appear at the receiver on plane electromagnetic waves together with interference and intrinsic noise, both centered stationary Gaussian random processes. Expressions are derived for the energy utilization factor, characterizing the signal to noise interference ratio relative to the signal noise ratio without interference. A comparison of that energy utilization factor corresponding to optimal processing of a narrow band signal and to nonoptimal processing of a wideband signal, respectively, yields the dependence of detectability and angle resolution on the signal bandwidth and the angular spacing of signal sources.

  19. Angle-Polarization Estimation for Coherent Sources with Linear Tripole Sensor Arrays.

    PubMed

    Wang, Kun; He, Jin; Shu, Ting; Liu, Zhong

    2016-01-01

    We propose a parallel factor (PARAFAC) analysis-based angle and polarization estimation algorithm for multiple coherent sources using a uniformly-spaced linear tripole sensor array. By forming a PARAFAC model using the spatial signature of the tripole array, the new algorithm requires neither spatial smoothing nor vector-field smoothing to decorrelate the signal coherency. We also establish that the angle-polarization parameters of K coherent signals can be uniquely determined by PARAFAC analysis, as long as the number of tripoles L ≥ 2K - 1 . In addition, the proposed algorithm can offer enhanced angle and polarization estimation accuracy by extending the interspacing of the tripoles beyond a half wavelength. PMID:26907273

  20. High-Frequency (>50 MHz) Medical Ultrasound Linear Arrays Fabricated From Micromachined Bulk PZT Materials

    PubMed Central

    Liu, Changgeng; Zhou, Qifa; Djuth, Frank T.; Shung, K. Kirk

    2012-01-01

    This paper describes the development and characterization of a high-frequency (65-MHz) ultrasound transducer linear array. The array was built from bulk PZT which was etched using an optimized chlorine-based plasma dry-etching process. The median etch rate of 8 μm/h yielded a good profile (wall) angle (>83°) and a reasonable processing time for etch depths up to 40 μm (which corresponds to a 50-MHz transducer). A backing layer with an acoustic impedance of 6 MRayl and a front-end polymer matching layer yielded a transducer bandwidth of 40%. The major parameters of the transducer have been characterized. The two-way insertion loss and crosstalk between adjacent channels at the center frequency are 26.5 and −25 dB, respectively. PMID:24626041

  1. Coherent-weighted three-dimensional image reconstruction in linear-array-based photoacoustic tomography.

    PubMed

    Wang, Depeng; Wang, Yuehang; Zhou, Yang; Lovell, Jonathan F; Xia, Jun

    2016-05-01

    While the majority of photoacoustic imaging systems used custom-made transducer arrays, commercially-available linear transducer arrays hold the benefits of affordable price, handheld convenience and wide clinical recognition. They are not widely used in photoacoustic imaging primarily because of the poor elevation resolution. Here, without modifying the imaging geometry and system, we propose addressing this limitation purely through image reconstruction. Our approach is based on the integration of two advanced image reconstruction techniques: focal-line-based three-dimensional image reconstruction and coherent weighting. We first numerically validated our approach through simulation and then experimentally tested it in phantom and in vivo. Both simulation and experimental results proved that the method can significantly improve the elevation resolution (up to 4 times in our experiment) and enhance object contrast. PMID:27231634

  2. Equivalent network of transverse dipoles on inset dielectric guide - Application to linear arrays

    NASA Astrophysics Data System (ADS)

    Rozzi, T.; Ma, Lizhuang; de Leo, Roberto; Morini, Antonio

    1990-03-01

    The inset dielectric guide (IDG) is an alternative to the image line, retaining most of its advantages without its main disadvantages. In particular, IDG makes it possible to realize low-cost leaky wave antennas with very pure polarization properties by laying thin metal strips (dipoles) on the air-dielectric interface. The scattering properties of thin metal strips are analyzed by means of a Ritz-Galerkin variational approach, taking into proper account the edge singularities. A variational expression for the equivalent circuit of the radiating dipole is derived, and this information is applied to the design of a tapered linear array by network methods. The array was built and tested, and it showed excellent performance.

  3. Plasmon enhanced linear and nonlinear photoluminescence in planar nanoparticle arrays (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Walsh, Gary F.; Dal Negro, Luca

    2015-09-01

    Light emission from metal nanoparticles has potential appications as a highly sensitive refractive index detector. In order for this protential to be realized the mechanics of plasmon enhanced photoluminescence (PL) in planar nanoparticle arrays must be understude. We present an experimental exploreation of emission spectra and realitive efficiency of gold PL in nanoplasmonic arrays. We demonstrate tunability of metal PL by nanoparticle size and discover the critical role of near-field interparticle coupling on emission efficiency. We show that direct excition of plasmon resonances by photoexcited electron-hole pairs is the primary contributer to the metalic nanoparticle emission spectrum. We additionally show that emission is quenched by near-field interactions between nanoparticles leading to spectral broading by increased non-radiative plasmon decay. Finally, we show a correlation between plasmon life-time and PL efficiency. We explore this phenominan for both linear and nonlinear PL. Experimental results are supported by numerical simulations of plasmon life-time.

  4. Combined real-time ultrasound plane wave compounding and linear array optoacoustics

    NASA Astrophysics Data System (ADS)

    Fournelle, Marc; Bost, Wolfgang; Tretbar, Steffen

    2015-07-01

    In optoacoustic imaging, the high optical contrast between different tissue types is combined with the high resolution and low scattering of ultrasound. Using adapted reconstruction algorithms, images of the distribution of light absorption in tissue can be obtained. Such as in any emerging modality, there is limited experience regarding the interpretation of optoacoustic images. For this reason, we developed a flexible hardware platform combining ultrasound imaging with optoacoustics. The system is based on the software processing of channel data and different types of reconstruction algorithms are implemented. It combines optoacoustic imaging based on linear arrays for detection with plane wave compounding ultrasound. Our system further includes a custom made probe based on a 7,5 MHz array, custom made fibre bundles for targeted light delivery and an acoustic coupling pad. The system was characterized on phantoms and first in-vivo datasets from subcutaneous vasculature were acquired.

  5. Coherent-weighted three-dimensional image reconstruction in linear-array-based photoacoustic tomography

    PubMed Central

    Wang, Depeng; Wang, Yuehang; Zhou, Yang; Lovell, Jonathan F.; Xia, Jun

    2016-01-01

    While the majority of photoacoustic imaging systems used custom-made transducer arrays, commercially-available linear transducer arrays hold the benefits of affordable price, handheld convenience and wide clinical recognition. They are not widely used in photoacoustic imaging primarily because of the poor elevation resolution. Here, without modifying the imaging geometry and system, we propose addressing this limitation purely through image reconstruction. Our approach is based on the integration of two advanced image reconstruction techniques: focal-line-based three-dimensional image reconstruction and coherent weighting. We first numerically validated our approach through simulation and then experimentally tested it in phantom and in vivo. Both simulation and experimental results proved that the method can significantly improve the elevation resolution (up to 4 times in our experiment) and enhance object contrast. PMID:27231634

  6. Angle-Polarization Estimation for Coherent Sources with Linear Tripole Sensor Arrays

    PubMed Central

    Wang, Kun; He, Jin; Shu, Ting; Liu, Zhong

    2016-01-01

    We propose a parallel factor (PARAFAC) analysis-based angle and polarization estimation algorithm for multiple coherent sources using a uniformly-spaced linear tripole sensor array. By forming a PARAFAC model using the spatial signature of the tripole array, the new algorithm requires neither spatial smoothing nor vector-field smoothing to decorrelate the signal coherency. We also establish that the angle-polarization parameters of K coherent signals can be uniquely determined by PARAFAC analysis, as long as the number of tripoles L≥2K−1. In addition, the proposed algorithm can offer enhanced angle and polarization estimation accuracy by extending the interspacing of the tripoles beyond a half wavelength. PMID:26907273

  7. NDT and SHM of Carbon Fiber Composites using Linear Drive MWM-Arrays

    NASA Technical Reports Server (NTRS)

    Washabaugh, Andrew; Martin, Christopher; Lyons, Robert; Grundy, David; Goldfine, Neil; Russell, Richard; Wincheski, Russell

    2012-01-01

    Carbon fiber composites are used in a wide range of structural applications due to their excellent specific strength and stiffness. However, the anisotropic mechanical and electrical properties associated with the fibers within each composite layer present challenges, and opportunities, for Nondestructive Testing (NDT) methods used to characterize and assess the structure condition. This includes composite condition after manufacture (such as fiber orientation and density, porosity, delamination, and bond strength) and during usage (such as damage from impact, fiber breakage, thermal exposure or applied stress). Ultrasonic and thermographic methods can address some of these challenges, but eddy current methods provide an alternative method for composite structures that contain a conducting material, such as carbon fibers or a metallic liner. This presentation reviews recent advances in the development of eddy current sensors and arrays for carbon fiber composite NDT and Structural Health Monitoring (SHM) applications. The focus is on eddy current sensor constructs with linear drive windings, such as MWM -Arrays, that induce currents primarily within the linear fibers of the composite. By combining this type of sensor construct with micromechanical models that relate composite constituent properties to measurable sensor responses, insight is obtained into the volumetric distribution of electrical properties within the composite and the associated manufacturing, damage, or strain conditions. With knowledge of the fiber layup, this MWM-Array technology is able to detect damage and strain/stress as a function of depth and fiber orientation. This work has been funded by NASA, NA V AIR and the Army for applications ranging from composite overwrapped pressure vessels (COPVs) to aircraft structures and rotorcraft blades. This presentation will specifically present background on the MWM-Array technology, results from the micromechanical modeling effort, and results from

  8. Application of linear array imaging techniques to the real-time inspection of airframe structures and substructures

    NASA Technical Reports Server (NTRS)

    Miller, James G.

    1995-01-01

    Development and application of linear array imaging technologies to address specific aging-aircraft inspection issues is described. Real-time video-taped images were obtained from an unmodified commercial linear-array medical scanner of specimens constructed to simulate typical types of flaws encountered in the inspection of aircraft structures. Results suggest that information regarding the characteristics, location, and interface properties of specific types of flaws in materials and structures may be obtained from the images acquired with a linear array. Furthermore, linear array imaging may offer the advantage of being able to compare 'good' regions with 'flawed' regions simultaneously, and in real time. Real-time imaging permits the inspector to obtain image information from various views and provides the opportunity for observing the effects of introducing specific interventions. Observation of an image in real-time can offer the operator the ability to 'interact' with the inspection process, thus providing new capabilities, and perhaps, new approaches to nondestructive inspections.

  9. Guided torsional wave generation of a linear in-plane shear piezoelectric array in metallic pipes.

    PubMed

    Zhou, Wensong; Yuan, Fuh-Gwo; Shi, Tonglu

    2016-02-01

    Cylindrical guided waves based techniques are effective and promising tools for damage detection in long pipes. The essential operations are generation and reception of guided waves in the structures utilizing transducers. A novel in-plane shear (d36 type) PMNT wafer is proposed to generate and receive the guided wave, especially the torsional waves, in metallic pipes. In contrast to the traditional wafer, this wafer will directly introduce in-plane shear deformation when electrical field is conveniently applied through its thickness direction. A single square d36 PMNT wafer is bonded on the surface of the pipe positioned collinearly with its axis, when actuated can predominantly generate torsional (T) waves along the axial direction, circumferential shear horizontal (C-SH) waves along circumferential direction, and other complex cylindrical Lamb-like wave modes along other helical directions simultaneously. While a linear array of finite square size d36 PMNT wafers was equally spaced circumferentially, when actuated simultaneously can nearly uniform axisymmetric torsional waves generate in pipes and non-symmetric wave modes can be suppressed greatly if the number of the d36 PMNT wafer is sufficiently large. This paper first presents the working mechanism of the linear d36 PMNT array from finite element analysis (FEA) by examining the constructive and destructive displacement wavefield phenomena in metallic pipes. Furthermore, since the amplitude of the received fundamental torsional wave signal strongly depends on frequency, a series of experiments are conducted to determine the frequency tuning curve for the torsional wave mode. All results indicate the linear d36 PMNT array has potential for efficiently generating uniform torsional wavefield of the fundamental torsional wave mode, which is more effective in monitoring structural health in metallic pipes. PMID:26548525

  10. Analysis of characteristics of plane microwave antennas with a linearly expanding aperture for disk antenna arrays

    NASA Astrophysics Data System (ADS)

    Zayarnyi, V. P.; Parpula, A. A.; Girich, V. S.

    2014-11-01

    Mathematical models constructed for plane symmetric microwave antennas with a linearly expanding aperture make it possible to calculate the directional patterns depending on the aperture configuration. The directional patterns for analogous antennas operating in the range 5.9-12.5 GHz are measured experimentally; good agreement between the theoretical and experimental results is observed. The regularities in the influence of the aperture configuration of the antennas under investigation on the shape of the principal lobe of their directional patterns are established; these regularities are used for designing disk antenna arrays of circular and sector scan on their basis.

  11. Detection of foreign body using fast thermoacoustic tomography with a multielement linear transducer array

    SciTech Connect

    Nie Liming; Xing Da; Yang Diwu; Zeng Lvming; Zhou Quan

    2007-04-23

    Current imaging modalities face challenges in clinical applications due to limitations in resolution or contrast. Microwave-induced thermoacoustic imaging may provide a complementary modality for medical imaging, particularly for detecting foreign objects due to their different absorption of electromagnetic radiation at specific frequencies. A thermoacoustic tomography system with a multielement linear transducer array was developed and used to detect foreign objects in tissue. Radiography and thermoacoustic images of objects with different electromagnetic properties, including glass, sand, and iron, were compared. The authors' results demonstrate that thermoacoustic imaging has the potential to become a fast method for surgical localization of occult foreign objects.

  12. Fabrication of High power, High-Efficiency Linear Array Diode Lasers by Pulse Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Zhang, Jing; Li, Hui; Qu, Yi; Bo, Baoxue

    2006-09-01

    InGaAlAs/AlGaAs/GaAs double-quantum-well (DQW) linear array diode lasers with asymmetric wide waveguide have been successfully fabricated by pulse anodic oxidation upon molecular beam epitaxy material growth. High-efficiency and high-power quasi-continuous-wave (QCW) output has been realized at 808 nm wavelength. The threshold current and slope efficiency of the prepared high-fill-factor QCW devices are 24 A and 1.25 A/W, respectively, and a maximum wall-plug efficiency of 51% has been achieved.

  13. Characterization of an advanced focal plane for multispectral linear array (MLA) application

    NASA Technical Reports Server (NTRS)

    King, P.; Botts, S.; Orias, G.; Yang, H. B.

    1984-01-01

    It is pointed out that the MLA instrument represents the next generation in the Landsat series of earth resources satellites. The MLA sensor concept utilizes a pushbroom scan mode to eliminate electromechanical scan mirrors, and the lower reliabililty and higher power dissipation which accompany their employment. The pushbroom scanner makes use of a linear array which consists generally of thousands of detectors oriented perpendicular to the along-track direction of the satellite. Test techniques have been developed for the measurement of the module parameters which are critical to MLA focal plane performance. These measurements include the determination of infrared responsivity, linearity over the dynamic range, temporal noise, and fixed pattern effects on each detector element of each module tested. Tests related to spectral response, crosstalk, and spot scan profiles are also conducted. A description is provided of the test equipment involved.

  14. Enhanced photovoltaic performance of an inclined nanowire array solar cell.

    PubMed

    Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2015-11-30

    An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays. PMID:26698807

  15. Nanotubular array solid oxide fuel cell.

    PubMed

    Motoyama, Munekazu; Chao, Cheng-Chieh; An, Jihwan; Jung, Hee Joon; Gür, Turgut M; Prinz, Friedrich B

    2014-01-28

    This report presents a demonstration and characterization of a nanotubular array of solid oxide fuel cells (SOFCs) made of one-end-closed hollow tube Ni/yttria-stabilized zirconia/Pt membrane electrode assemblies (MEAs). The tubular MEAs are nominally ∼5 μm long and have <500 nm outside diameter with total MEA thickness of nearly 50 nm. Open circuit voltages up to 660 mV (vs air) and power densities up to 1.3 μW cm(-2) were measured at 550 °C using H2 as fuel. The paper also introduces a fabrication methodology primarily based on a template process involving atomic layer deposition and electrodeposition for building the nanotubular MEA architecture as an important step toward achieving high surface area ultrathin SOFCs operating in the intermediate to low-temperature regime. A fabricated nanotubular SOFC theoretically attains a 20-fold increase in the effective surface, while projections indicate the possibility of achieving up to 40-fold. PMID:24266776

  16. Multiple target three-dimensional coordinate estimation for bistatic MIMO radar with uniform linear receive array

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Huan; Long, Libing; Liao, Guisheng; Griffiths, Hugh

    2013-12-01

    A novel scheme to achieve three-dimensional (3D) target location in bistatic radar systems is evaluated. The proposed scheme develops the additional information of the bistatic radar, that is the transmit angles, to estimate the 3D coordinates of the targets by using multiple-input multiple-output techniques with a uniform circular array on transmit and a uniform linear array on receive. The transmit azimuth, transmit elevation angles and receive cone angle of the targets are first extracted from the receive data and the 3D coordinates are then calculated on the basis of these angles. The geometric dilution of precision which is based on the root Cramer-Rao bound of the angles, is derived to evaluate the performance bound of the proposed scheme. Further, an ESPRIT based algorithm is developed to estimate the 3D coordinates of the targets. The advantages of this scheme are that the hardware of the receive array is reduced and the 3D coordinates of the targets can be estimated in the absence of the range information in bistatic radar. Simulations and analysis show that the proposed scheme has potential to achieve good performance with low-frequency radar.

  17. Two-dimensional imaging via a narrowband MIMO radar system with two perpendicular linear arrays.

    PubMed

    Wang, Dang-wei; Ma, Xiao-yan; Su, Yi

    2010-05-01

    This paper presents a system model and method for the 2-D imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. Furthermore, the imaging formulation for our method is developed through a Fourier integral processing, and the parameters of antenna array including the cross-range resolution, required size, and sampling interval are also examined. Different from the spatial sequential procedure sampling the scattered echoes during multiple snapshot illuminations in inverse synthetic aperture radar (ISAR) imaging, the proposed method utilizes a spatial parallel procedure to sample the scattered echoes during a single snapshot illumination. Consequently, the complex motion compensation in ISAR imaging can be avoided. Moreover, in our array configuration, multiple narrowband spectrum-shared waveforms coded with orthogonal polyphase sequences are employed. The mainlobes of the compressed echoes from the different filter band could be located in the same range bin, and thus, the range alignment in classical ISAR imaging is not necessary. Numerical simulations based on synthetic data are provided for testing our proposed method. PMID:20040416

  18. On mapping algorithms to linear and fault-tolerant systolic arrays

    SciTech Connect

    Kumar, V.K.P.; Tsai, Y.C.

    1989-03-01

    The authors develop a simple mapping technique to design systolic arrays with limited I/O capability. Using this, improved systolic algorithms are derived for some matrix computations, on linearly connected arrays of processing elements (PEs) with constant I/O bandwidth. The important features of these designs are modularity with constant hardware in each PE, few control lines, simple data input/ouput format, and improved delay time. They extend the technique to design an optimal time systolic algorithm for n x n matrix multiplication. In this model, the propagation delay is assumed to be proportional to wire length. Fault reconfiguration is achieved by using buffers to bypass faulty PE's, which does not affect the clock rate of the system. The unidirectional flow of control and data in our design assures correctness of the algorithm in the presence of faulty PE's. This design can be implemented on reconfigurable fault-tolerant VLSI arrays using the Diogenes methodology. The authors compare their designs to those in the literature and are shown to be superior with respect to I/O format, control, and delay from input to output.

  19. First Experiments with Planar Wire Arrays on U Michigan's Linear Transformer Driver

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Weller, M. E.; Shrestha, I. K.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M.; Stafford, A.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Jordan, N. M.; Gilgenbach, R. M.

    2014-10-01

    For petawatt-class Z-pinch accelerators, a Linear Transformer Driver (LTD)-driven accelerator promises to be (at a given pinch current and implosion time) more efficient than the conventionally used Marx-driven accelerator. Because there exists almost no data on how wire arrays radiate on LTD-based machines in the USA, it is very important to perform radiation and plasma physics studies on this new type of generator. We report on the first outcome of the new partnership with University of Michigan (UM), which resulted in successful UNR-UM experiments on the low-impedance MAIZE generator with planar wire arrays (PWA). PWA is a novel wire array load that was introduced and tested in detail on high-impedance Zebra at UNR during the last years and found to be the most efficient radiator. Implosion of Al Double PWAs of different configurations were achieved on MAIZE, observed with a set of various diagnostics which include x-ray diode detectors, x-ray spectroscopy and imaging, and shadowgraphy. Al and Mg plasmas of more than 450 eV were studied in detail. Research supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. G. Patel and A. M. Steiner supported by Sandia National Laboratories. D. A. Yager-Elorriaga supported by NSF GF.

  20. Development of a 64 channel ultrasonic high frequency linear array imaging system.

    PubMed

    Hu, ChangHong; Zhang, Lequan; Cannata, Jonathan M; Yen, Jesse; Shung, K Kirk

    2011-12-01

    In order to improve the lateral resolution and extend the field of view of a previously reported 48 element 30 MHz ultrasound linear array and 16-channel digital imaging system, the development of a 256 element 30 MHz linear array and an ultrasound imaging system with increased channel count has been undertaken. This paper reports the design and testing of a 64 channel digital imaging system which consists of an analog front-end pulser/receiver, 64 channels of Time-Gain Compensation (TGC), 64 channels of high-speed digitizer as well as a beamformer. A Personal Computer (PC) is used as the user interface to display real-time images. This system is designed as a platform for the purpose of testing the performance of high frequency linear arrays that have been developed in house. Therefore conventional approaches were taken it its implementation. Flexibility and ease of use are of primary concern whereas consideration of cost-effectiveness and novelty in design are only secondary. Even so, there are many issues at higher frequencies but do not exist at lower frequencies need to be solved. The system provides 64 channels of excitation pulsers while receiving simultaneously at a 20-120 MHz sampling rate to 12-bits. The digitized data from all channels are first fed through Field Programmable Gate Arrays (FPGAs), and then stored in memories. These raw data are accessed by the beamforming processor to re-build the image or to be downloaded to the PC for further processing. The beamformer that applies delays to the echoes of each channel is implemented with the strategy that combines coarse (8.3 ns) and fine delays (2 ns). The coarse delays are integer multiples of the sampling clock rate and are achieved by controlling the write enable pin of the First-In-First-Out (FIFO) memory to obtain valid beamforming data. The fine delays are accomplished with interpolation filters. This system is capable of achieving a maximum frame rate of 50 frames per second. Wire phantom images

  1. Linear bolometer array using a high TCR VOx-Au film

    NASA Astrophysics Data System (ADS)

    Smith, Evan M.; Ginn, James C.; Warren, Andrew P.; Long, Christopher J.; Panjwani, Deep; Peale, Robert E.; Shelton, David J.

    2014-06-01

    We present a design for a low-noise bolometer linear array based on the temperature-dependent conductivity of a VOx- Au film. Typical thin film bolometers must compromise between low resistivity to limit Johnson noise and high temperature coefficient of resistivity (TCR) to maximize responsivity. Our vanadium oxide is alloyed with a small concentration of gold by co-sputtering, which gives very low resistivity and very high TCR simultaneously. The film is fabricated on an air bridge device having high thermal conductivity and small thermal time constant optimized for 30 to 60 Hz frame rates. The linear array functions as a low-power profile sensor with a modulated bias. For 1 V bias, we predict responsivity exceeding 1200 V/W. Johnson noise dominates with predicted NEP values as low as 1.0 × 10-11 W/Hz1/2. Preliminary device testing shows film resistivity below 2.5 Ω-cm with TCR exceeding -2.0%. Preliminary measurements of NEP and D* are reported.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  3. Handheld Thermoacoustic Scanning System Based on a Linear-array Transducer.

    PubMed

    Ji, Zhong; Ding, Wenzheng; Ye, Fanghao; Lou, Cunguang

    2016-07-01

    To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally. First, the vertical and lateral resolution of the system is discussed. Next, real-time imaging of a moving object, obtained with an image capture rate of 20 frame/s, is described. Finally, a phantom experiment is detailed, investigating the overall imaging capability. The results show that this system achieves rapid scanning with a large field of view. The system has the obvious advantages of being handheld, not using coupled fluids, and achieving real-time imaging with a large field of view, which make this MITIS more suitable for clinical applications. PMID:26294659

  4. Off-Grid Direction of Arrival Estimation Based on Joint Spatial Sparsity for Distributed Sparse Linear Arrays

    PubMed Central

    Liang, Yujie; Ying, Rendong; Lu, Zhenqi; Liu, Peilin

    2014-01-01

    In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach. PMID:25420150

  5. Off-grid direction of arrival estimation based on joint spatial sparsity for distributed sparse linear arrays.

    PubMed

    Liang, Yujie; Ying, Rendong; Lu, Zhenqi; Liu, Peilin

    2014-01-01

    In the design phase of sensor arrays during array signal processing, the estimation performance and system cost are largely determined by array aperture size. In this article, we address the problem of joint direction-of-arrival (DOA) estimation with distributed sparse linear arrays (SLAs) and propose an off-grid synchronous approach based on distributed compressed sensing to obtain larger array aperture. We focus on the complex source distribution in the practical applications and classify the sources into common and innovation parts according to whether a signal of source can impinge on all the SLAs or a specific one. For each SLA, we construct a corresponding virtual uniform linear array (ULA) to create the relationship of random linear map between the signals respectively observed by these two arrays. The signal ensembles including the common/innovation sources for different SLAs are abstracted as a joint spatial sparsity model. And we use the minimization of concatenated atomic norm via semidefinite programming to solve the problem of joint DOA estimation. Joint calculation of the signals observed by all the SLAs exploits their redundancy caused by the common sources and decreases the requirement of array size. The numerical results illustrate the advantages of the proposed approach. PMID:25420150

  6. Effects of a near-field rigid sphere scatterer on the performance of linear microphone array beamformers.

    PubMed

    Hu, Yuxiang; Zhou, Haoran; Lu, Jing; Qiu, Xiaojun

    2016-08-01

    Beamformers enable a microphone array to capture acoustic signals from a sound source with high signal to noise ratio in a noisy environment, and the linear microphone array is of particular importance, in practice, due to its simplicity and easy implementation. A linear microphone array sometimes is used near some scattering objects, which affect its beamforming performance. This paper develops a numerical model with a linear microphone array near a rigid sphere for both far-field plane wave and near-field sources. The effects of the scatterer on two typical beamformers, i.e., the delay-and-sum beamformer and the superdirective beamformer, are investigated by both simulations and experiments. It is found that the directivity factor of both beamformers improves due to the increased equivalent array aperture when the size of the array is no larger than that of the scatter. With the increase of the array size, the directivity factor tends to deteriorate at high frequencies because of the rising side-lobes. When the array size is significantly larger than that of the scatterer, the scattering has hardly any influence on the beamforming performance. PMID:27586725

  7. Spraylon fluorocarbon encapsulation for silicon solar cell arrays

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A development program was performed for evaluating, modifying, and optimizing the Lockheed formulated liquid transparent filmforming Spraylon fluorocarbon protective coating for silicon solar cells and modules. The program objectives were designed to meet the requirements of the low-cost automated solar cell array fabrication process. As part of the study, a computer program was used to establish the limits of the safe working stress in the coated silicon solar cell array system under severe thermal shock.

  8. Amorphous silicon cell array powered solar tracking apparatus

    DOEpatents

    Hanak, Joseph J.

    1985-01-01

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

  9. Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling

    PubMed Central

    Eckert, Paulo Roberto; Flores Filho, Aly Ferreira; Perondi, Eduardo; Ferri, Jeferson; Goltz, Evandro

    2016-01-01

    This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator. PMID:26978370

  10. Design Methodology of a Dual-Halbach Array Linear Actuator with Thermal-Electromagnetic Coupling.

    PubMed

    Eckert, Paulo Roberto; Flores Filho, Aly Ferreira; Perondi, Eduardo; Ferri, Jeferson; Goltz, Evandro

    2016-01-01

    This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator. PMID:26978370

  11. Microfabricated atomic vapor cell arrays for magnetic field measurements

    SciTech Connect

    Woetzel, S.; Schultze, V.; IJsselsteijn, R.; Schulz, T.; Anders, S.; Stolz, R.; Meyer, H.-G.

    2011-03-15

    We describe a method for charging atomic vapor cells with cesium and buffer gas. By this, it is possible to adjust the buffer gas pressure in the cells with good accuracy. Furthermore, we present a new design of microfabricated vapor cell arrays, which combine silicon wafer based microfabrication and ultrasonic machining to achieve the arrays of thermally separated cells with 50 mm{sup 3} volume. With cells fabricated in the outlined way, intrinsic magnetic field sensitivities down to 300 fT/Hz{sup 1/2} are reached.

  12. Digital Radiography and Computed Tomography Project -- Fully Integrated Linear Detector ArrayStatus Report

    SciTech Connect

    Tim Roney; Robert Seifert; Bob Pink; Mike Smith

    2011-09-01

    The field-portable Digital Radiography and Computed Tomography (DRCT) x-ray inspection systems developed for the Project Manager for NonStockpile Chemical Materiel (PMNSCM) over the past 13 years have used linear diode detector arrays from two manufacturers; Thomson and Thales. These two manufacturers no longer produce this type of detector. In the interest of insuring the long term viability of the portable DRCT single munitions inspection systems and to improve the imaging capabilities, this project has been investigating improved, commercially available detectors. During FY-10, detectors were evaluated and one in particular, manufactured by Detection Technologies (DT), Inc, was acquired for possible integration into the DRCT systems. The remainder of this report describes the work performed in FY-11 to complete evaluations and fully integrate the detector onto a representative DRCT platform.

  13. Higher-charged vortices in mixed linear-nonlinear circular arrays

    SciTech Connect

    Dong Liangwei; Huang Changming; Zhong Shunsheng; Li Chunyan; Li Huijun

    2011-10-15

    We report on the dynamics of vortex solitons in circular waveguide arrays featuring modulation of both the linear and nonlinear refractive indices. Out-of-phase competition between both effects supports multipeaked vortex solitons with higher topological charges. A vortex solution can be found only when its charge is less than half of the number of waveguides. It may expand or shrink radially with the propagation constant, depending on the ratio between the topological charge and the number of waveguides. Surprisingly, vortex solitons with higher charges are more stable than those with lower charges, which is very rare and contrary to the stability of vortices in uniform or lattice-modulated media. Our findings suggest an alternative way for the realization of stable vortex solitons with higher charges.

  14. A novel PIN photodetector with double linear arrays for rainfall prediction

    NASA Astrophysics Data System (ADS)

    Yan, Yao; Xiong, Liu; Li, Yuan; Zhaohua, Zhang; Tianling, Ren

    2015-09-01

    A novel PIN (positive-intrinsic-negative) photodetector with double linear arrays that can be used to measure the diameter of precipitation particles and the space between two droplets in clouds is proposed. The sensitive unit is the PIN photodiode. The chip with a size of 10 × 8 mm2 has 128 photodiodes, and each row has 64 photodiodes. The device design, fabrication process and package are introduced in the paper. The photocurrent of the packaged chip was systematically tested with a red laser. Also the diameter of one water drop and the space between two water drops were measured. The minimum raindrop diameter which can be tested in this paper is 100 μm. This device can be useful for rainfall prediction. Project supported by the National Natural Science Foundation of China (No. 61434001) and the ‘Thousands Talents’ Program for Pioneer Researchers and Its Innovation Team, China.

  15. Design and optimization of multi-class series-parallel linear electromagnetic array artificial muscle.

    PubMed

    Li, Jing; Ji, Zhenyu; Shi, Xuetao; You, Fusheng; Fu, Feng; Liu, Ruigang; Xia, Junying; Wang, Nan; Bai, Jing; Wang, Zhanxi; Qin, Xiansheng; Dong, Xiuzhen

    2014-01-01

    Skeletal muscle exhibiting complex and excellent precision has evolved for millions of years. Skeletal muscle has better performance and simpler structure compared with existing driving modes. Artificial muscle may be designed by analyzing and imitating properties and structure of skeletal muscle based on bionics, which has been focused on by bionic researchers, and a structure mode of linear electromagnetic array artificial muscle has been designed in this paper. Half sarcomere is the minimum unit of artificial muscle and electromagnetic model has been built. The structural parameters of artificial half sarcomere actuator were optimized to achieve better movement performance. Experimental results show that artificial half sarcomere actuator possesses great motion performance such as high response speed, great acceleration, small weight and size, robustness, etc., which presents a promising application prospect of artificial half sarcomere actuator. PMID:24211938

  16. Fabrication and Characterization of Linear Terahertz Detector Arrays Based on Lithium Tantalate Crystal

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Wang, Jun; Gou, Jun; Huang, Zehua; Jiang, Yadong

    2015-01-01

    Two samples of 30-pixel linear terahertz detector arrays (TDAs) were fabricated based on lithium tantalate (LT) crystals. Pixel readout circuit (ROC) was designed to extract the weak current signal of TDAs. A test platform was established for performance evaluation of TDA+ROC components. By using a 2.52THz laser as radiation source, the test results reveal that average voltage responsivities of the components were larger than 7000V/W and non-uniformity no more than 2.1%. Average noise equivalent power ( NEP) of one sample was measured to be 1.5×10-9 W/Hz1/2, which is low enough and desirable for high performance THz detector.

  17. Three-dimensional endoscopic photoacoustic imaging based on multielement linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2011-09-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube, and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. Furthermore, pig normal rectal tissue and mouse breast tumor tissue in an ex vivo cavity model were imaged by the system. The reconstructed three-dimensional photoacoustic image presented the structural information of normal and lesion tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  18. Three-dimensional endoscopic photoacoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2012-03-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  19. Three-dimensional endoscopic photoacoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2011-11-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  20. Innervation zones of fasciculating motor units: observations by a linear electrode array

    PubMed Central

    Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E.; Rymer, William Z.; Zhou, Ping

    2015-01-01

    This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs. PMID:26029076

  1. Melting and freezing of argon in a granular packing of linear mesopore arrays.

    PubMed

    Schaefer, Christof; Hofmann, Tommy; Wallacher, Dirk; Huber, Patrick; Knorr, Klaus

    2008-05-01

    Freezing and melting of Ar condensed in a granular packing of template-grown arrays of linear mesopores (SBA-15, mean pore diameter 8 nm) has been studied by specific heat measurements C as a function of fractional filling of the pores. While interfacial melting leads to a single melting peak in C, homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the pores result in a complex freezing mechanism explainable only by a consideration of regular adsorption sites (in the cylindrical mesopores) and irregular adsorption sites (in niches of the rough external surfaces of the grains and at points of mutual contact of the powder grains). The tensile pressure release upon reaching bulk-liquid-vapor coexistence quantitatively accounts for an upward shift of the melting and freezing temperature observed while overfilling the mesopores. PMID:18518308

  2. A gate array structure for the efficient project of digital circuits: The unit cell array

    NASA Astrophysics Data System (ADS)

    Geisler, Olaf

    In this study the principles for the development of a unit-cell-array-master, which shows all the advantages of gate-arrays, are presented. By taking the cabling influence on the chip surface into account, a stochastic model of cabling for sea-of-gates-structures is used, which allows establishment of the minimal dimensions of the master-components for the cabling. As regards the cell architecture, the gate isolation technique and smaller asymmetric p-n channel transistor pairs are employed. With logical structures such as Ram, Rom or PLA (programmed logic array), the Gt density increases. The analysis of gate-array cabling capacity shows that transistors with commercial gate-arrays are often of too great dimension. A greater transistor density and a lower dissipation without any performance decrease are possible by using smaller transistors and a parallel connection in circuit paths with higher cabling capacity. Apart from its initial high cost, unit cell array is interesting from an economical point of view.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  4. Weapon detection using a wideband millimeter-wave linear array imaging technique

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Collins, H. D.; Hall, Thomas E.

    1994-03-01

    A wideband millimeter-wave imaging technique has been developed by the Pacific Northwest Laboratory (PNL) for the detection of concealed weapons carried by personnel through high- security areas, such as airports. A practical airport system based on this technique should be capable of real-time image frame rate of 10 to 30 frames per second. This technique, similar to an extremely high-resolution radar system, actively probes the target with millimeter-waves and reconstructs an image from the backscattered phase and amplitude data. The primary goal of the system is the detection of weapons and the placement of the detected weapon on the body. An important additional goal is the identification of detected items, which requires a high resolution imaging technique. An experimental system has been developed at PNL which has gathered millimeter wave imagery from clothed mannequins and human beings carrying concealed weapons. This system is capable of forming images in excess of 1 meter by 2 meters at resolutions on the order of 1 cm, and is capable of scanning in less than 5 seconds. This experimental system could be enhanced to function in real time by eliminating the relatively slow mechanical scan. A sequentially switched linear array of transceiver antennas would allow real-time gathering of the imaging information, since the data would be electronically scanned in the lateral direction and electronically swept in frequency. This allows formation of a 2D image from a 1D array of transceiver antennas.

  5. Contrast-based moving target detection with the randomized linear receive array

    NASA Astrophysics Data System (ADS)

    Ranney, Kenneth; Martone, Anthony; Innocenti, Roberto; Nguyen, Lam

    2012-06-01

    The Army Research Laboratory (ARL) has, in the past, demonstrated the effectiveness of low frequency, ultrawideband radar for detection of slow-moving targets located behind walls. While these initial results were promising, they also indicated that sidelobe artifacts produced by moving target indication (MTI) processing could pose serious problems. Such artifacts induced false alarms and necessitated the introduction of a tracker stage to eliminate them. Of course, the tracker algorithm was also imperfect, and it tended to pass any persistent, nearly collocated false alarms. In this work we describe the incorporation of a sidelobe-reduction technique-the randomized linear receiver array (RA)-into our MTI processing chain. To perform this investigation, we leverage data collected by ARL's synchronous impulse reconstruction (SIRE) radar. We begin by calculating MTI imagery using both the non-random and randomized array methods. We then compare the sidelobe levels in each image and quantify the differences. Finally, we apply a local-contrast target detection algorithm based on constant false alarm rate (CFAR) principles, and we analyze probabilities of detection and false alarm for each MTI image.

  6. Imaging of downward-looking linear array SAR using three-dimensional spatial smoothing MUSIC algorithm

    NASA Astrophysics Data System (ADS)

    Zhang, Siqian; Kuang, Gangyao

    2014-10-01

    In this paper, a novel three-dimensional imaging algorithm of downward-looking linear array SAR is presented. To improve the resolution, multiple signal classification (MUSIC) algorithm has been used. However, since the scattering centers are always correlated in real SAR system, the estimated covariance matrix becomes singular. To address the problem, a three-dimensional spatial smoothing method is proposed in this paper to restore the singular covariance matrix to a full-rank one. The three-dimensional signal matrix can be divided into a set of orthogonal three-dimensional subspaces. The main idea of the method is based on extracting the array correlation matrix as the average of all correlation matrices from the subspaces. In addition, the spectral height of the peaks contains no information with regard to the scattering intensity of the different scattering centers, thus it is difficulty to reconstruct the backscattering information. The least square strategy is used to estimate the amplitude of the scattering center in this paper. The above results of the theoretical analysis are verified by 3-D scene simulations and experiments on real data.

  7. Micropallet arrays for the separation of single, adherent cells.

    PubMed

    Salazar, Georgina To'a; Wang, Yuli; Young, Grace; Bachman, Mark; Sims, Christopher E; Li, G P; Allbritton, Nancy L

    2007-01-15

    The selection and collection of single cells from within a heterogeneous population is required to produce genetically engineered cell lines, to develop new stem cell lines, and for single-cell studies. We describe a new platform for the positive selection of single live mammalian cells while the cells remain adherent to their growth surface. Cells were grown on arrays of microfabricated, releasable elements composed of SU-8 polymer termed "cell pallets". The presence of air between the elements restricted the cells to the top surfaces of the pallets. Single pallets situated within large arrays of pallets were released on demand using a single, focused, laser pulse. The laser pulses were low in energy (2-5 muJ) and did not detach nearby, nontargeted pallets. Since the SU-8 pallets and the underlying glass substrate were optically transparent, the cells on the pallets could be visualized by microscopy before and after release. Over 90% of cells remained attached to the pallet during laser-based release. The feasibility of growing the cells from the released pallets into clonal colonies was demonstrated. The pallet array system permits adherent cells to be inspected using conventional microscopy and selected cells released for further analysis. The ability to assess cells while they remain adherent to a surface will broaden the number of attributes that can be utilized for cell separation, for example, cell shape, cytoskeletal properties, and other attributes. PMID:17222037

  8. A microfluidic array with cellular valving for single cell co-culture.

    PubMed

    Frimat, Jean-Philippe; Becker, Marco; Chiang, Ya-Yu; Marggraf, Ulrich; Janasek, Dirk; Hengstler, Jan G; Franzke, Joachim; West, Jonathan

    2011-01-21

    We present a highly parallel microfluidic approach for contacting single cell pairs. The approach combines a differential fluidic resistance trapping method with a novel cellular valving principle for homotypic and heterotypic single cell co-culturing. Differential fluidic resistance was used for sequential single cell arraying, with the adhesion and flattening of viable cells within the microstructured environment acting to produce valves in the open state. Reversal of the flow was used for the sequential single cell arraying of the second cell type. Plasma stencilling, along the linear path of least resistance, was required to confine the cells within the trap regions. Prime flow conditions with minimal shear stress were identified for highly efficient cell arraying (∼99%) and long term cell culture. Larger trap dimensions enabled the highest levels of cell pairing (∼70%). The single cell co-cultures were in close proximity for the formation of connexon structures and the study of contact modes of communication. The research further highlights the possibility of using the natural behaviour of cells as the working principle behind responsive microfluidic elements. PMID:20978708

  9. Thermal-independent properties of PIN-PMN-PT single-crystal linear-array ultrasonic transducers.

    PubMed

    Chen, Ruimin; Wu, Jinchuan; Ho Lam, Kwok; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K Kirk

    2012-12-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In(1/2)Nb(1/2))-Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PIN-PMN-PT) and binary Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PMNPT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a -6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  10. Effect of surface waves on the characteristics of a linear phased array in the presence of a dielectric layer

    NASA Astrophysics Data System (ADS)

    Kniazev, S. T.; Panchenko, B. A.

    A Green-function approach is taken to the determination of the surface-wave spectrum for a phased array with a dielectric layer, taking into account the relationship between bulk and surface waves. Numerical results are presented on the radiation characteristics of a linear phased array consisting of strip dipoles. Dipole input admittance and bulk-wave admittance are determined as a function of phasing angle.

  11. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications.

    PubMed

    Wang, I-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy. PMID:27483492

  12. 3D Ta/TaO x /TiO2/Ti synaptic array and linearity tuning of weight update for hardware neural network applications

    NASA Astrophysics Data System (ADS)

    Wang, I.-Ting; Chang, Chih-Cheng; Chiu, Li-Wen; Chou, Teyuh; Hou, Tuo-Hung

    2016-09-01

    The implementation of highly anticipated hardware neural networks (HNNs) hinges largely on the successful development of a low-power, high-density, and reliable analog electronic synaptic array. In this study, we demonstrate a two-layer Ta/TaO x /TiO2/Ti cross-point synaptic array that emulates the high-density three-dimensional network architecture of human brains. Excellent uniformity and reproducibility among intralayer and interlayer cells were realized. Moreover, at least 50 analog synaptic weight states could be precisely controlled with minimal drifting during a cycling endurance test of 5000 training pulses at an operating voltage of 3 V. We also propose a new state-independent bipolar-pulse-training scheme to improve the linearity of weight updates. The improved linearity considerably enhances the fault tolerance of HNNs, thus improving the training accuracy.

  13. Measurements of hf auroral clutter using the verona ava linear array radar (VALAR). Report for June 1990-June 1991

    SciTech Connect

    Choi, D.S.; Weijers, B.; Myers, N.B.

    1994-03-01

    Measurements of high frequency (HF) auroral clutter using the Verona Ava Linear Array Radar (VALAR) system are presented. VALAR is an experimental HF backscatter system capable of obtaining high resolution synoptic mapping of HF auroral clutter. The receive system includes a 700 meter long linear array. providing the high azimuthal resolution required for determining the spatial distribution of HF auroral clutter. Since the completion of the system at the end of 1989, data acquisition campaigns have been carried out on a near-monthly basis. In this report, the authors provide a brief description of VALAR and present preliminary measurements of three types of phenomena: ground backscatter, slant-F, and auroral backscatter.

  14. An addressable cell array for a platform of biosensor chips

    NASA Astrophysics Data System (ADS)

    Yang, Seungkyoung; Choi, Soo-hee; Jung, Moon Youn; Song, Kibong; Park, Jeong Won

    2013-05-01

    In order to detect interested matters in fields, various lab-on-a-chips where chemical, physical, or biological sensors are loaded have been developed. eNOSE can be a representative example among them. Because animals can sense 300~1000 different chemicals by olfactory system - smell -, the olfactory system has been spotlighted as new materials in the field of sensing. Those investigations, however, are usually focused on how to detect signals from the olfactory neurons or receptors loaded on chips and enhance sensing efficacy of chips. Therefore, almost of those chips are designed for only one material sensing. Multi-sensing using multi-channels will be needed when the olfactory systems are adopted well on chips. For multiple sensing, we developed an addressable cell array. The chip has 38 cell-chambers arranged in a circle shape and different cell types of thirty eight can be allocated with specific addresses on the chip without any complex valve system. In order to confirm the cell addressing, we loaded EGFP-transfected and empty vector-transfected HEK293a cells into inlets of the cell array in a planned address and those cells were positioned into each chamber by brief aspiration. The arrayed cells were confirmed as a specific pattern through EGFP and nuclei staining. This cell array which can generate address of sensor materials like cells with their own specification is expected to be applied to a platform for a biosensor chip at various sensing fields.

  15. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    NASA Astrophysics Data System (ADS)

    Spurgeon, Joshua Michael

    Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

  16. Design and programming of systolic array cells for signal processing

    SciTech Connect

    Smith, R.A.W.

    1989-01-01

    This thesis presents a new methodology for the design, simulation, and programming of systolic arrays in which the algorithms and architecture are simultaneously optimized. The algorithms determine the initial architecture, and simulation is used to optimize the architecture. The simulator provides a register-transfer level model of a complete systolic array computation. To establish the validity of this design methodology two novel programmable systolic array cells were designed and programmed. The cells were targeted for applications in high-speed signal processing and associated matrix computations. A two-chip programmable systolic array cell using a 16-bit multiplier-accumulator chip and a semi-custom VLSI controller chip was designed and fabricated. A low chip count allows large arrays to be constructed, but the cell is flexible enough to be a building-block for either one- or two-dimensional systolic arrays. Another more flexible and powerful cell using a 32-bit floating-point processor and a second VLSI controller chip was also designed. It contains several architectural features that are unique in a systolic array cell: (1) each instruction is 32 bits, yet all resources can be updated every cycle, (2) two on-chip interchangeable memories are used, and (3) one input port can be used as either a global or local port. The key issues involved in programming the cells are analyzed in detail. A set of modules is developed which can be used to construct large programs in an effective manner. The utility of this programming approach is demonstrated with several important examples.

  17. Infrared line cameras based on linear arrays for industrial temperature measurement

    NASA Astrophysics Data System (ADS)

    Drogmoeller, Peter; Hofmann, Guenter; Budzier, Helmut; Reichardt, Thomas; Zimmerhackl, Manfred

    2002-03-01

    The PYROLINE/ MikroLine cameras provide continuous, non-contact measurement of linear temperature distributions. Operation in conjunction with the IR_LINE software provides data recording, real-time graphical analysis, process integration and camera-control capabilities. One system is based on pyroelectric line sensors with either 128 or 256 elements, operating at frame rates of 128 and 544 Hz respectively. Temperatures between 0 and 1300DGRC are measurable in four distinct spectral ranges; 8-14micrometers for low temperatures, 3-5micrometers for medium temperatures, 4.8-5.2micrometers for glass-temperature applications and 1.4-1.8micrometers for high temperatures. A newly developed IR-line camera (HRP 250) based upon a thermoelectrically cooled, 160-element, PbSe detector array operating in the 3 - 5 micrometers spectral range permits the thermal gradients of fast moving targets to be measured in the range 50 - 180 degree(s)C at a maximum frequency of 18kHz. This special system was used to measure temperature distributions on rotating tires at velocities of more than 300 km/h (190 mph). A modified version of this device was used for real-time measurement of disk-brake rotors under load. Another line camera consisting a 256 element InGaAs array was developed for the spectral range of 1.4 - 1.8 micrometers to detect impurities of polypropylene and polyethylene in raw cotton at frequencies of 2.5 - 5 kHz.

  18. Low-Concentration-Ratio Solar-Cell Arrays

    NASA Technical Reports Server (NTRS)

    Biss, M. S.; Reed, David A., Jr.

    1986-01-01

    Paper presents design concept for mass-producible arrays of solar electric batteries and concentrators tailored to individual requirements. Arrays intended primarily for space stations needing about 100 kW of power. However, modular, lightweight, compact, and relatively low-cost design also fulfill requirements of some terrestrial applications. Arrays built with currently available materials. Pultrusions, injectionmolded parts, and composite materials used extensively to keep weight low. For added flexibility in design and construction, silicon and gallium arsenide solar-cell panels interchangeable.

  19. Large area magnetic micropallet arrays for cell colony sorting.

    PubMed

    Cox-Muranami, Wesley A; Nelson, Edward L; Li, G P; Bachman, Mark

    2016-01-01

    A new micropallet array platform for adherent cell colony sorting has been developed. The platform consisted of thousands of square plastic pallets, 270 μm by 270 μm on each side, large enough to hold a single colony of cells. Each pallet included a magnetic core, allowing them to be collected with a magnet after being released using a microscope mounted laser system. The micropallets were patterned from 1002F epoxy resist and were fabricated on translucent, gold coated microscope slides. The gold layer was used as seed for electroplating the ferromagnetic cores within every individual pallet. The gold layer also facilitated the release of each micropallet during laser release. This array allows for individual observation, sorting and collection of isolated cell colonies for biological cell colony research. In addition to consistent release and recovery of individual colonies, we demonstrated stable biocompatibility and minimal loss in imaging quality compared to previously developed micropallet arrays. PMID:26606460

  20. High-throughput cell analysis using multiplexed array technologies.

    PubMed

    Beske, Oren E; Goldbard, Simon

    2002-09-15

    The desire for more biologically relevant data from primary screening has resulted in a dramatic increase of cell-based assays in HTS labs. Consequently, new cell-array technologies are being developed to increase the quality and quantity of data emerging from such screens. These technologies take the form of both positional and non-positional formats, each with their own advantages. Notably, screens using these technologies generate databases of high-quality data that can be analyzed in ways currently not possible. The power of cell-based assays combined with new array and analytical technologies will enable the condensation of serial drug discovery processes, thereby decreasing the time and cost of taking a hit compound into clinical trials. Here, we compare array strategies being developed towards the goal of integrating multiplexed cell-based assays into HTS. PMID:12546879

  1. Modular thermoelectric cell is easily packaged in various arrays

    NASA Technical Reports Server (NTRS)

    Epstein, J.

    1965-01-01

    Modular thermoelectric cells are easily packaged in various arrays to form power supplies and have desirable voltage and current output characteristics. The cells employ two pairs of thermoelectric elements, each pair being connected in parallel between two sets of aluminum plates. They can be used as solar energy conversion devices.

  2. Interventional multispectral photoacoustic imaging with a clinical linear array ultrasound probe for guiding nerve blocks

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; West, Simeon J.; Nikitichev, Daniil I.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2016-03-01

    Accurate identification of tissue structures such as nerves and blood vessels is critically important for interventional procedures such as nerve blocks. Ultrasound imaging is widely used as a guidance modality to visualize anatomical structures in real-time. However, identification of nerves and small blood vessels can be very challenging, and accidental intra-neural or intra-vascular injections can result in significant complications. Multi-spectral photoacoustic imaging can provide high sensitivity and specificity for discriminating hemoglobin- and lipid-rich tissues. However, conventional surface-illumination-based photoacoustic systems suffer from limited sensitivity at large depths. In this study, for the first time, an interventional multispectral photoacoustic imaging (IMPA) system was used to image nerves in a swine model in vivo. Pulsed excitation light with wavelengths in the ranges of 750 - 900 nm and 1150 - 1300 nm was delivered inside the body through an optical fiber positioned within the cannula of an injection needle. Ultrasound waves were received at the tissue surface using a clinical linear array imaging probe. Co-registered B-mode ultrasound images were acquired using the same imaging probe. Nerve identification was performed using a combination of B-mode ultrasound imaging and electrical stimulation. Using a linear model, spectral-unmixing of the photoacoustic data was performed to provide image contrast for oxygenated and de-oxygenated hemoglobin, water and lipids. Good correspondence between a known nerve location and a lipid-rich region in the photoacoustic images was observed. The results indicate that IMPA is a promising modality for guiding nerve blocks and other interventional procedures. Challenges involved with clinical translation are discussed.

  3. MLAOS: a multi-point linear array of optical sensors for coniferous foliage clumping index measurement.

    PubMed

    Qu, Yonghua; Fu, Lizhe; Han, Wenchao; Zhu, Yeqing; Wang, Jindi

    2014-01-01

    The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8-10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy. PMID:24859029

  4. Optofluidic holographic microscopy with custom field of view (FoV) using a linear array detector.

    PubMed

    Bianco, V; Paturzo, M; Marchesano, V; Gallotta, I; Di Schiavi, E; Ferraro, P

    2015-05-01

    Simple and effective imaging strategies are of utmost interest for applications on a lab-on-chip scale. In fact, the majority of diagnostic tools for medical as well as biotechnological studies still employ image-based approaches. Having onboard the chip a compact but powerful imaging apparatus with multiple imaging capabilities, such as 3D dynamic focusing along the optical axis, unlimited field of view (FoV) and double outputs, namely, intensity and quantitative phase-contrast maps of biological objects, is of extreme importance for the next generation of Lab-on-a-Chip (LoC) devices. Here we present a coherent 3D microscopy approach with a holographic modality that is specifically suitable for studying biological samples while they simply flow along microfluidic paths. The LoC device is equipped with a compact linear array detector to capture and generate a new conceptual type of a digital hologram in the space-time domain, named here as Space-Time Digital Hologram (STDH). The reported results show that the method is a promising diagnostic tool for optofluidic investigations of biological specimens. PMID:25832808

  5. MLAOS: A Multi-Point Linear Array of Optical Sensors for Coniferous Foliage Clumping Index Measurement

    PubMed Central

    Qu, Yonghua; Fu, Lizhe; Han, Wenchao; Zhu, Yeqing; Wang, Jindi

    2014-01-01

    The canopy foliage clumping effect is primarily caused by the non-random distribution of canopy foliage. Currently, measurements of clumping index (CI) by handheld instruments is typically time- and labor-intensive. We propose a low-cost and low-power automatic measurement system called Multi-point Linear Array of Optical Sensors (MLAOS), which consists of three above-canopy and nine below-canopy optical sensors that capture plant transmittance at different times of the day. Data communication between the MLAOS node is facilitated by using a ZigBee network, and the data are transmitted from the field MLAOS to a remote data server using the Internet. The choice of the electronic element and design of the MLAOS software is aimed at reducing costs and power consumption. A power consumption test showed that, when a 4000 mAH Li-ion battery is used, a maximum of 8–10 months of work can be achieved. A field experiment on a coniferous forest revealed that the CI of MLAOS may reveal a clumping effect that occurs within the canopy. In further work, measurement of the multi-scale clumping effect can be achieved by utilizing a greater number of MLAOS devices to capture the heterogeneity of the plant canopy. PMID:24859029

  6. Effects of nanopillar array diameter and spacing on cancer cell capture and cell behaviors

    NASA Astrophysics Data System (ADS)

    Wang, Shunqiang; Wan, Yuan; Liu, Yaling

    2014-10-01

    While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs and manipulation of cytomorphology in future.While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs

  7. Optimal Sensor Arrangements in Angle of Arrival (AoA) and Range Based Localization with Linear Sensor Arrays

    PubMed Central

    Herath, Sanvidha C. K.; Pathirana, Pubudu N.

    2013-01-01

    This paper investigates the linear separation requirements for Angle-of-Arrival (AoA) and range sensors, in order to achieve the optimal performance in estimating the position of a target from multiple and typically noisy sensor measurements. We analyse the sensor-target geometry in terms of the Cramer–Rao inequality and the corresponding Fisher information matrix, in order to characterize localization performance with respect to the linear spatial distribution of sensors. Here in this paper, we consider both fixed and adjustable linear sensor arrays. PMID:24036585

  8. Linear and non-linear performance of transducer and pupil in Calliphora retinula cells.

    PubMed Central

    Leutscher-Hazelhoff, J T

    1975-01-01

    1. Intracellular recordings have been made from the blowfly (Calliphora erythrocephala) retinula cell; apart from the transducer mechanism, these cells also feature a pupil mechanism. 2. At several mean intensity levels, within the apparently linear range of response, frequency characteristics of amplitude and phase and responses to 'delta'-flashes and 'delta'-flash pairs have been obtained. 3. Fourier methods have shown these responses to be mutually compatible, confirming linearity in these circumstances. 4. Non-linear behaviour can be made to appear at the lower frequencies when the modulation depth is increased. 5. Non-linearities can also appear through application of the superposition test: a low frequency sine wave, modulated so as to elicit an apparently linear response, and a high frequence sine wave which does not give rise to non-linearity even at the highest modulation depths can, when superimposed, yield a greater response to the latter when situated at the minima of the former than at its maxima. 6. At frequencies above approximately 1 Hz these superposition non-linearities are attributed to the transducer mechanism gain control. Below this frequency the pupil mechanism takes part considerably in the retinula cell's total observed gain control: its characteristics remain yet to be cleared up. 7. The transducer's linear and non-linear properties fit in closely with those of the Fuortes-Hodgkin model which couples increases in gain and time constants. 8. The Fuortes-Hodgkin model will probably require some quantitative modifications in the originally treated case of Limulus, on account of its pupil. 9. Finally, the merits of Veringa's diffusion model, and the possibility of eventually joining this model with the Fuortes-Hodgkin one are pointed out briefly. PMID:1142250

  9. Plasmonic Tipless Pyramid Arrays for Cell Poration.

    PubMed

    Courvoisier, Sébastien; Saklayen, Nabiha; Huber, Marinus; Chen, Jun; Diebold, Eric D; Bonacina, Luigi; Wolf, Jean-Pierre; Mazur, Eric

    2015-07-01

    Improving the efficiency, cell survival, and throughput of methods to modify and control the genetic expression of cells is of great benefit to biology and medicine. We investigate, both computationally and experimentally, a nanostructured substrate made of tipless pyramids for plasmonic-induced transfection. By optimizing the geometrical parameters for an excitation wavelength of 800 nm, we demonstrate a 100-fold intensity enhancement of the electric near field at the cell-substrate contact area, while the low absorption typical for gold is maintained. We demonstrate that such a substrate can induce transient poration of cells by a purely optically induced process. PMID:26079771

  10. High power density fuel cell comprising an array of microchannels

    SciTech Connect

    Morse, Jeffrey D.; Upadhye, Ravindra S.; Spadaccini, Christopher M.; Park, Hyung Gyu

    2013-10-15

    A fuel cell according to one embodiment includes a porous electrolyte support structure defining an array of microchannels, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and oxidant electrodes formed along other of the microchannels. A method of making a fuel cell according to one embodiment includes forming an array of walls defining microchannels therebetween using at least one of molding, stamping, extrusion, injection and electrodeposition; processing the walls to make the walls porous, thereby creating a porous electrolyte support structure; forming anode electrodes along some of the microchannels; and forming cathode electrodes along other of the microchannels. Additional embodiments are also disclosed.

  11. Cell pairing using microwell array electrodes based on dielectrophoresis.

    PubMed

    Yoshimura, Yuki; Tomita, Masahiro; Mizutani, Fumio; Yasukawa, Tomoyuki

    2014-07-15

    We report a simple device with an array of 10,000 (100 × 100) microwells for producing vertical pairs of cells in individual microwells with a rapid manipulation based on positive dielectrophoresis (p-DEP). The areas encircled with micropoles which fabricated from an electrical insulating photosensitive polymer were used as microwells. The width (14 μm) and depth (25 μm) of the individual microwells restricted the size to two vertically aligned cells. The DEP device for the manipulation of cells consisted of a microfluidic channel with an upper indium tin oxide (ITO) electrode and a lower microwell array electrode fabricated on an ITO substrate. Mouse myeloma cells stained in green were trapped within 1 s in the microwells by p-DEP by applying an alternating current voltage between the upper ITO and the lower microwell array electrode. The cells were retained inside the wells even after switching off the voltage and washing with a fluidic flow. Other myeloma cells stained in blue were then trapped in the microwells occupied by the cells stained in green to form the vertical cell pairing in the microwells. Cells stained in different colors were paired within only 1 min and a pairing efficiency of over 50% was achieved. PMID:24947270

  12. Solar cell array design handbook, volume 1

    NASA Technical Reports Server (NTRS)

    Rauschenbach, H. S.

    1976-01-01

    Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

  13. An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1988-01-01

    The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

  14. Cicada-inspired cell-instructive nanopatterned arrays

    NASA Astrophysics Data System (ADS)

    Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F.; Su, Bo; Ryadnov, Maxim G.

    2014-11-01

    Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion.

  15. Cicada-inspired cell-instructive nanopatterned arrays.

    PubMed

    Diu, Ting; Faruqui, Nilofar; Sjöström, Terje; Lamarre, Baptiste; Jenkinson, Howard F; Su, Bo; Ryadnov, Maxim G

    2014-01-01

    Biocompatible surfaces hold key to a variety of biomedical problems that are directly related to the competition between host-tissue cell integration and bacterial colonisation. A saving solution to this is seen in the ability of cells to uniquely respond to physical cues on such surfaces thus prompting the search for cell-instructive nanoscale patterns. Here we introduce a generic rationale engineered into biocompatible, titanium, substrates to differentiate cell responses. The rationale is inspired by cicada wing surfaces that display bactericidal nanopillar patterns. The surfaces engineered in this study are titania (TiO2) nanowire arrays that are selectively bactericidal against motile bacteria, while capable of guiding mammalian cell proliferation according to the type of the array. The concept holds promise for clinically relevant materials capable of differential physico-mechanical responses to cellular adhesion. PMID:25409910

  16. Current role of radial and curved-linear arrayed EUS scopes for diagnosis of pancreatic abnormalities in Japan.

    PubMed

    Irisawa, Atsushi

    2011-05-01

    To elucidate the current status of radial and curved-linear arrayed endoscopic ultrasonography (EUS), the author conducted a survey using a questionnaire at different institutions to assess the following. 1. Number of EUS procedures conducted annually for pancreatic malignancies. 2. Role of radial arrayed EUS for pancreatic abnormalities. 3. Role of curved-linear arrayed EUS for pancreatic abnormalities. 4. Indication of EUS-guided fine-needle aspiration biopsy (EUS-FNA) for pancreatic abnormalities. 5. Percentage of EUS-FNA among the cases carried out with EUS for pancreatic abnormalities. 6. Experience of EUS with contrast harmonic echo for pancreatic malignancies and its indications. 7. Experience of elastography on EUS for pancreatic abnormalities. In Japan, although usage of curved-linear arrayed EUS has become popular for both EUS-FNA and for screening, radial EUS is widely used for diagnosing pancreatic abnormalities. Endosonographers must understand the respective advantages and disadvantages of EUS devices and carry out EUS procedures appropriately. PMID:21535192

  17. The Effects of Linear Microphone Array Changes on Computed Sound Exposure Level Footprints

    NASA Technical Reports Server (NTRS)

    Mueller, Arnold W.; Wilson, Mark R.

    1997-01-01

    Airport land planning commissions often are faced with determining how much area around an airport is affected by the sound exposure levels (SELS) associated with helicopter operations. This paper presents a study of the effects changing the size and composition of a microphone array has on the computed SEL contour (ground footprint) areas used by such commissions. Descent flight acoustic data measured by a fifteen microphone array were reprocessed for five different combinations of microphones within this array. This resulted in data for six different arrays for which SEL contours were computed. The fifteen microphone array was defined as the 'baseline' array since it contained the greatest amount of data. The computations used a newly developed technique, the Acoustic Re-propagation Technique (ART), which uses parts of the NASA noise prediction program ROTONET. After the areas of the SEL contours were calculated the differences between the areas were determined. The area differences for the six arrays are presented that show a five and a three microphone array (with spacing typical of that required by the FAA FAR Part 36 noise certification procedure) compare well with the fifteen microphone array. All data were obtained from a database resulting from a joint project conducted by NASA and U.S. Army researchers at Langley and Ames Research Centers. A brief description of the joint project test design, microphone array set-up, and data reduction methodology associated with the database are discussed.

  18. Linear mode photon counting from visible to MWIR with HgCdTe avalanche photodiode focal plane arrays

    NASA Astrophysics Data System (ADS)

    Sullivan, William; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

    2015-05-01

    Results of characterization data on linear mode photon counting (LMPC) HgCdTe electron-initiated avalanche photodiode (e-APD)focal plane arrays (FPA) are presented that reveal an improved understanding and the growing maturity of the technology. The first successful 2x8 LMPC FPA was fabricated in 2010 [1]. Since then a process validation lot of 2x8 arrays was fabricated. Five arrays from this lot were characterized that replicated the previous 2x8 LMPC array performance. In addition, it was unambiguously verified that readout integrated circuit (ROIC) glow was responsible for most of the false event rate (FER) of the 2010 array. The application of a single layer metal blocking layer between the ROIC and the detector array and optimization of the ROIC biases reduced the FER by an order of magnitude. Photon detection efficiencies (PDEs) of greater than 50% were routinely demonstrated across 5 arrays, with one array reaching a PDE of 70%. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 μm to 25 μm resulting in a 2x increase in E-APD gain from 470 on the 2010 array to 1100 on one of the 2013 FPAs. Mean single photon signal to noise ratios of >12 were demonstrated at excess noise factors of 1.2-1.3. NASA Goddard Space Flight Center (GSFC) performed measurements on the delivered FPA that verified the PDE and FER data.

  19. Method of low temperature operation of an electrochemical cell array

    DOEpatents

    Singh, Prabhakar; Ruka, Roswell J.; Bratton, Raymond J.

    1994-01-01

    In the method of operating an electrochemical cell generator apparatus containing a generator chamber (20) containing an array of cells (12) having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas (F) contacts the outside of the cells (12) and the generating chamber normally operates at over 850.degree. C., where N.sub.2 gas is fed to contact the interior electrode of the cells (12) in any case when the generating chamber (20) temperature drops for whatever reason to within the range of from 550.degree. C. to 800.degree. C., to eliminate cracking within the cells (12).

  20. Studies of encapsulant materials for terrestrial solar-cell arrays

    NASA Technical Reports Server (NTRS)

    Carmichael, D. C. (Compiler)

    1975-01-01

    Study 1 of this contract is entitled ""Evaluation of World Experience and Properties of Materials for Encapsulation of Terrestrial Solar-Cell Arrays.'' The approach of this study is to review and analyze world experience and to compile data on properties of encapsulants for photovoltaic cells and for related applications. The objective of the effort is to recommend candidate materials and processes for encapsulating terrestrial photovoltaic arrays at low cost for a service life greater than 20 years. The objectives of Study 2, ""Definition of Encapsulant Service Environments and Test Conditions,'' are to develop the climatic/environmental data required to define the frequency and duration of detrimental environmental conditions in a 20-year array lifetime and to develop a corresponding test schedule for encapsulant systems.

  1. Dielectrophoretic registration of living cells to a microelectrode array.

    PubMed

    Gray, Darren S; Tan, John L; Voldman, Joel; Chen, Christopher S

    2004-02-15

    We present a novel microfabricated device to simultaneously and actively trap thousands of single mammalian cells in alignment with a planar microelectrode array. Thousands of 3 micromdiameter trapping electrodes were fabricated within the bottom of a parallel-plate flow chamber. Cells were trapped on the electrodes and held against destabilizing fluid flows by dielectrophoretic forces generated in the device. In general, each electrode trapped only one cell. Adhesive regions were patterned onto the surface in alignment with the traps such that cells adhered to the array surface and remained in alignment with the electrodes. By driving the device with different voltages, we showed that trapped cells could be killed by stronger electric fields. However, with weaker fields, cells were not damaged during trapping, as indicated by the similar morphologies and proliferation rates of trapped cells versus controls. As a test of the device, we patterned approximately 20000 cells onto a 1cm(2) grid of rectangular adhesive regions, with two electrodes and thus two cells per rectangle. Our method obtained 70+/-1% fidelity versus 17+/-1% when using an existing cell-registration technique. By allowing the placement of desired numbers of cells at specified locations, this approach addresses many needs to manipulate and register cells to the surfaces of biosensors and other devices with high precision and fidelity. PMID:14709396

  2. Dielectrophoretic registration of living cells to a microelectrode array.

    PubMed

    Gray, Darren S; Tan, John L; Voldman, Joel; Chen, Christopher S

    2004-07-15

    We present a novel microfabricated device to simultaneously and actively trap thousands of single mammalian cells in alignment with a planar microelectrode array. Thousands of 3 Ipm diameter trapping electrodes were fabricated within the bottom of a parallel-plate flow chamber. Cells were trapped on the electrodes and held against destabilizing fluid flows by dielectrophoretic forces generated in the device. In general, each electrode trapped only one cell. Adhesive regions were patterned onto the surface in alignment with the traps such that cells adhered to the array surface and remained in alignment with the electrodes. By driving the device with different voltages, we showed that trapped cells could be killed by stronger electric fields. However, with weaker fields, cells were not damaged during trapping, as indicated by the similar morphologies and proliferation rates of trapped cells versus controls. As a test of the device, we patterned approximately 20,000 cells onto aI cm2 grid of rectangular adhesive regions, with two electrodes and thus two cells per rectangle. Our method obtained 70 +/- 1% fidelity versus 17 +/- 1% when using an existing cell-registration technique. By allowing the placement of desired numbers of cells at specified locations, this approach addresses many needs to manipulate and register cells to the surfaces of biosensors and other devices with high precision and fidelity. PMID:15198083

  3. A High-Frequency Linear Ultrasonic Array Utilizing an Interdigitally Bonded 2-2 Piezo-Composite

    PubMed Central

    Cannata, Jonathan M.; Williams, Jay A.; Zhang, Lequan; Hu, Chang-Hong; Shung, K. Kirk

    2011-01-01

    This paper describes the development of a high-frequency 256-element linear ultrasonic array utilizing an interdigitally bonded (IB) piezo-composite. Several IB composites were fabricated with different commercial and experimental piezoelectric ceramics and evaluated to determine a suitable formulation for use in high-frequency linear arrays. It was found that the fabricated fine-scale 2–2 IB composites outperformed 1–3 IB composites with identical pillar- and kerf-widths. This result was not expected and lead to the conclusion that dicing damage was likely the cause of the discrepancy. Ultimately, a 2–2 composite fabricated using a fine-grain piezoelectric ceramic was chosen for the array. The composite was manufactured using one IB operation in the azimuth direction to produce approximately 19-μm-wide pillars separated by 6-μm-wide kerfs. The array had a 50 μm (one wavelength in water) azimuth pitch, two matching layers, and 2 mm elevation length focused to 7.3 mm using a polymethylpentene (TPX) lens. The measured pulse-echo center frequency for a representative array element was 28 MHz and −6-dB band-width was 61%. The measured single-element transmit −6-dB directivity was estimated to be 50°. The measured insertion loss was 19 dB after compensating for the effects of attenuation and diffraction in the water bath. A fine-wire phantom was used to assess the lateral and axial resolution of the array when paired with a prototype system utilizing a 64-channel analog beamformer. The −6-dB lateral and axial resolutions were estimated to be 125 and 68 μm, respectively. An anechoic cyst phantom was also imaged to determine the minimum detectable spherical inclusion, and thus the 3-D resolution of the array and beamformer. The minimum anechoic cyst detected was approximately 300 μm in diameter. PMID:21989884

  4. High linearity SPAD and TDC array for TCSPC and 3D ranging applications

    NASA Astrophysics Data System (ADS)

    Villa, Federica; Lussana, Rudi; Bronzi, Danilo; Dalla Mora, Alberto; Contini, Davide; Tisa, Simone; Tosi, Alberto; Zappa, Franco

    2015-01-01

    An array of 32x32 Single-Photon Avalanche-Diodes (SPADs) and Time-to-Digital Converters (TDCs) has been fabricated in a 0.35 μm automotive-certified CMOS technology. The overall dimension of the chip is 9x9 mm2. Each pixel is able to detect photons in the 300 nm - 900 nm wavelength range with a fill-factor of 3.14% and either to count them or to time stamp their arrival time. In photon-counting mode an in-pixel 6-bit counter provides photon-numberresolved intensity movies at 100 kfps, whereas in photon-timing mode the 10-bit in-pixel TDC provides time-resolved maps (Time-Correlated Single-Photon Counting measurements) or 3D depth-resolved (through direct time-of-flight technique) images and movies, with 312 ps resolution. The photodetector is a 30 μm diameter SPAD with low Dark Count Rate (120 cps at room temperature, 3% hot-pixels) and 55% peak Photon Detection Efficiency (PDE) at 450 nm. The TDC has a 6-bit counter and a 4-bit fine interpolator, based on a Delay Locked Loop (DLL) line, which makes the TDC insensitive to process, voltage, and temperature drifts. The implemented sliding-scale technique improves linearity, giving 2% LSB DNL and 10% LSB INL. The single-shot precision is 260 ps rms, comprising SPAD, TDC and driving board jitter. Both optical and electrical crosstalk among SPADs and TDCs are negligible. 2D fast movies and 3D reconstructions with centimeter resolution are reported.

  5. Evaluation of linear array human papillomavirus genotyping using automatic optical imaging software.

    PubMed

    Jeronimo, J; Wentzensen, N; Long, R; Schiffman, M; Dunn, S T; Allen, R A; Walker, J L; Gold, M A; Zuna, R E; Sherman, M E; Wacholder, S; Wang, S S

    2008-08-01

    Variations in biological behavior suggest that each carcinogenic human papillomavirus (HPV) type should be considered individually in etiologic studies. HPV genotyping assays might have clinical applications if they are approved for use by the FDA. A widely used genotyping assay is the Roche Linear Array HPV genotyping test (LA). We used LA to genotype the HPV isolates from cervical specimens from women with the full spectrum of cervical disease: cervical cancer, cervical intraepithelial neoplasia (CIN), and HPV infections. To explore the feasibility and value of the automated reading of the LA results, we custom-designed novel, optical imaging software that provides optical density measurements of LA bands. We compared unmagnified visual examination with the automated measurements. The two measurements were highly associated. By either method, the threshold between a negative and a positive result was fairly sharp, with a clear bimodal distribution. Visually, most positive results were judged to be strong or medium, with fewer equivocal results categorized as weak (9.5% of positive samples), very weak (6.5% of positive samples), or extremely weak (7.7% of positive samples). The automated measurements of the intensities were significantly associated with the strength of the visual categories (P < 0.001). At the extremes of the automated signal intensities (< or = 20 units or > or = 120 units), the bands were almost always categorized visually as negative and positive, respectively. In the equivocal zone (20 to 119 units), specimens were more increasingly likely to be judged to be visually positive as the number of other, definite infections on the same strip increased (P for trend < 0.001). Multiple, concurrent infections comprise > or = 25% of HPV infections; thus, any systematic visual tendency that influences their evaluation when the result is equivocal should be minimized. Therefore, automated reading is probably worth development if easy-to-calibrate hardware

  6. Human Papillomavirus Load Measured by Linear Array Correlates with Quantitative PCR in Cervical Cytology Specimens

    PubMed Central

    Gravitt, Patti E.; Long, Rodney; Schiffman, Mark; Dunn, S. Terence; Carreon, J. Daniel; Allen, Richard A.; Gunja, Munira; Zuna, Rosemary E.; Sherman, Mark E.; Gold, Michael A.; Walker, Joan L.; Wang, Sophia S.

    2012-01-01

    Carcinogenic human papillomavirus (HPV) infections are necessary causes of most anogenital cancers. Viral load has been proposed as a marker for progression to cancer precursors but has been confirmed only for HPV16. Challenges in studying viral load are related to the lack of validated assays for a large number of genotypes. We compared viral load measured by Linear Array (LA) HPV genotyping with the gold standard, quantitative PCR (Q-PCR). LA genotyping and Q-PCR were performed in 143 cytology specimens from women referred to colposcopy. LA signal strength was measured by densitometry. Correlation coefficients and receiver operating characteristic (ROC) analyses were used to evaluate analytical and clinical performance. We observed a moderate to strong correlation between the two quantitative viral load measurements, ranging from an R value of 0.61 for HPV31 to an R value of 0.86 for HPV52. We also observed agreement between visual LA signal strength evaluation and Q-PCR. Both quantifications agreed on the disease stages with highest viral load, which varied by type (cervical intraepithelial neoplasia grade 2 [CIN2] for HPV52, CIN3 for HPV16 and HPV33, and cancer for HPV18 and HPV31). The area under the curve (AUC) for HPV16 Q-PCR at the CIN3 cutoff was 0.72 (P = 0.004), and the AUC for HPV18 LA at the CIN2 cutoff was 0.78 (P = 0.04). Quantification of LA signals correlates with the current gold standard for viral load, Q-PCR. Analyses of viral load need to address multiple infections and type attribution to evaluate whether viral load has clinical value beyond the established HPV16 finding. Our findings support conducting comprehensive studies of viral load and cervical cancer precursors using quantitative LA genotyping data. PMID:22337992

  7. Microfluidic cell arrays for metabolic monitoring of stimulated cardiomyocytes.

    PubMed

    Cheng, Wei; Klauke, Norbert; Smith, Godfrey; Cooper, Jonathan M

    2010-04-01

    An array of PDMS microchambers was aligned to an array of sensor electrodes and stimulating microelectrodes, which was used for the electrochemical monitoring of the metabolic activity of single isolated adult ventricular myocytes inside the chamber array, stimulated within a transient electric field. The effect of the accumulation of metabolic byproducts in the limited extracellular volume of the picolitre chambers was demonstrated by measuring single muscle cell contraction optically, while concomitant changes in intracellular calcium transients and pH were recorded independently using fluorescent indicator dyes. Both the amplitude of the cell shortening and the magnitude of the intracellular calcium transients decreased over time and both nearly ceased after 20 min of continuous stimulation in the limited extracellullar volume. The intracellular pH decreased gradually during 20 min of continuous stimulation after which a dramatic pH drop was observed, indicating the breakdown of the intracellular buffering capacity. After continuous stimulation, intracellular lactate was released into the microchamber through cell electroporation and was detected electrochemically at a lactate microbiosensor, within the chamber. A mitochondrial uncoupler was used to mimic ischaemia and thus to enhance the cellular content of lactate. Under these circumstances, intracellular lactate concentrations were found to have risen to approximately 15 mM. This array system has the potential of simultaneous electrochemical and optical monitoring of extracellular and intracellular metabolites from single beating heart cells at a controlled metabolic state. PMID:20333720

  8. Method of construction of a multi-cell solar array

    NASA Technical Reports Server (NTRS)

    Routh, D. E.; Hollis, B. R., Jr.; Feltner, W. R. (Inventor)

    1979-01-01

    The method of constructing a high voltage, low power, multicell solar array is described. A solar cell base region is formed in a substrate such as but not limited to silicon or sapphire. A protective coating is applied on the base and a patterned etching of the coating and base forms discrete base regions. A semiconductive junction and upper active region are formed in each base region, and defined by photolithography. Thus, discrete cells which are interconnected by metallic electrodes are formed.

  9. Comparative Study on Synthesizing Reconfigurable Time- Modulated Linear Arrays using Differential Evolution, Artificial Bee Colony and Particle Swarm Optimization

    NASA Astrophysics Data System (ADS)

    Mandal, S. K.; Singh, Harshavardhan; Mahanti, G. K.; Ghatak, Rowdra

    2014-10-01

    This paper presents a new technique based on optimization tools to design phase only, digitally controlled, reconfigurable antenna arrays through time modulation. In the proposed approach, the on-time durations of the time-modulated elements and the static amplitudes of the array elements are perturbed in such a way that the same on-time sequence and discrete values of static amplitudes for four bit digital attenuators produces either a pencil or a flat-top beam pattern, depending on the suitable discrete phase distributions of five bit digital phase shifters. In order to illustrate the technique, three optimization tools: differential evolution (DE), artificial bee colony (ABC), and particle swarm optimization (PSO) are employed and their performances are compared. The numerical results for a 20-element linear array are presented.

  10. Imaging method for downward-looking sparse linear array three-dimensional synthetic aperture radar based on reweighted atomic norm

    NASA Astrophysics Data System (ADS)

    Bao, Qian; Han, Kuoye; Lin, Yun; Zhang, Bingchen; Liu, Jianguo; Hong, Wen

    2016-01-01

    We propose an imaging algorithm for downward-looking sparse linear array three-dimensional synthetic aperture radar (DLSLA 3-D SAR) in the circumstance of cross-track sparse and nonuniform array configuration. Considering the off-grid effect and the resolution improvement, the algorithm combines pseudo-polar formatting algorithm, reweighed atomic norm minimization (RANM), and a parametric relaxation-based cyclic approach (RELAX) to improve the imaging performance with a reduced number of array antennas. RANM is employed in the cross-track imaging after pseudo-polar formatting the DLSLA 3-D SAR echo signal, then the reconstructed results are refined by RELAX. By taking advantage of the reweighted scheme, RANM can improve the resolution of the atomic norm minimization, and outperforms discretized compressive sensing schemes that suffer from off-grid effect. The simulated and real data experiments of DLSLA 3-D SAR verify the performance of the proposed algorithm.