Science.gov

Sample records for multi channel analyzer

  1. Web-based multi-channel analyzer

    DOEpatents

    Gritzo, Russ E.

    2003-12-23

    The present invention provides an improved multi-channel analyzer designed to conveniently gather, process, and distribute spectrographic pulse data. The multi-channel analyzer may operate on a computer system having memory, a processor, and the capability to connect to a network and to receive digitized spectrographic pulses. The multi-channel analyzer may have a software module integrated with a general-purpose operating system that may receive digitized spectrographic pulses for at least 10,000 pulses per second. The multi-channel analyzer may further have a user-level software module that may receive user-specified controls dictating the operation of the multi-channel analyzer, making the multi-channel analyzer customizable by the end-user. The user-level software may further categorize and conveniently distribute spectrographic pulse data employing non-proprietary, standard communication protocols and formats.

  2. MULTI-CHANNEL PULSE HEIGHT ANALYZER

    DOEpatents

    Boyer, K.; Johnstone, C.W.

    1958-11-25

    An improved multi-channel pulse height analyzer of the type where the device translates the amplitude of each pulse into a time duration electrical quantity which is utilized to control the length of a train of pulses forwarded to a scaler is described. The final state of the scaler for any one train of pulses selects the appropriate channel in a magnetic memory in which an additional count of one is placed. The improvement consists of a storage feature for storing a signal pulse so that in many instances when two signal pulses occur in rapid succession, the second pulse is preserved and processed at a later time.

  3. A low power Multi-Channel Analyzer

    SciTech Connect

    Anderson, G.A.; Brackenbush, L.W.

    1993-06-01

    The instrumentation used in nuclear spectroscopy is generally large, is not portable, and requires a lot of power. Key components of these counting systems are the computer and the Multi-Channel Analyzer (MCA). To assist in performing measurements requiring portable systems, a small, very low power MCA has been developed at Pacific Northwest Laboratory (PNL). This MCA is interfaced with a Hewlett Packard palm top computer for portable applications. The MCA can also be connected to an IBM/PC for data storage and analysis. In addition, a real-time time display mode allows the user to view the spectra as they are collected.

  4. Investigating neuronal activity by SPYCODE multi-channel data analyzer.

    PubMed

    Bologna, Luca Leonardo; Pasquale, Valentina; Garofalo, Matteo; Gandolfo, Mauro; Baljon, Pieter Laurens; Maccione, Alessandro; Martinoia, Sergio; Chiappalone, Michela

    2010-08-01

    Multi-channel acquisition from neuronal networks, either in vivo or in vitro, is becoming a standard in modern neuroscience in order to infer how cell assemblies communicate. In spite of the large diffusion of micro-electrode-array-based systems, researchers usually find it difficult to manage the huge quantity of data routinely recorded during the experimental sessions. In fact, many of the available open-source toolboxes still lack two fundamental requirements for treating multi-channel recordings: (i) a rich repertoire of algorithms for extracting information both at a single channel and at the whole network level; (ii) the capability of autonomously repeating the same set of computational operations to 'multiple' recording streams (also from different experiments) and without a manual intervention. The software package we are proposing, named SPYCODE, was mainly developed to respond to the above constraints and generally to offer the scientific community a 'smart' tool for multi-channel data processing. PMID:20554151

  5. Multi-channel amplitude analyzer for x-ray investigations

    NASA Astrophysics Data System (ADS)

    Karetnikov, M. D.; Klimov, A. I.; Zaitsev, V. I.

    2005-07-01

    The suggested device is implemented as one-module instrument including: a spectrometric amplifier providing superposition rejection, basic level restoration, track-and-hold functions, a precision ADC completed with the buffer memory; high-voltage power supply for X-ray detector; hardware interface with PC. All this resulted in a compact, functionally completed instrument for X-ray analysis. The device is a convenient instrument for X-ray fluorescent analysis, radiation diffraction studies, determination of element composition of a substance, customs and forensic expertise, medical diagnostics, testing of food products for presence of heavy elements, and other studies associated with X-ray applications. The functional diagram of the multi-channel amplitude analyzer is given in Fig. 1. The control circuit includes programmable logic device (PLD) EPM7128AETC100-lO manufactured by Altera Corporation, high performance C8051A021 processor by Cygnal Integrated Products and AS7C3256-12TC static memory by Cypress.

  6. Fractional channel multichannel analyzer

    DOEpatents

    Brackenbush, L.W.; Anderson, G.A.

    1994-08-23

    A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynchronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board. 9 figs.

  7. Fractional channel multichannel analyzer

    DOEpatents

    Brackenbush, Larry W.; Anderson, Gordon A.

    1994-01-01

    A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynscronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board.

  8. Industrial SO2 emissions monitoring using a portable multi-channel gas analyzer with an optimized retrieval algorithm

    NASA Astrophysics Data System (ADS)

    Sun, Y. W.; Liu, C.; Xie, P. H.; Hartl, A.; Chan, K. L.; Tian, Y.; Wang, W.; Qin, M.; Liu, J. G.; Liu, W. Q.

    2015-12-01

    In this paper, we demonstrate achieving accurate industrial SO2 emissions monitoring using a portable multi-channel gas analyzer with an optimized retrieval algorithm. The introduced analyzer features with large dynamic measurement range and correction of interferences from other co-existing infrared absorbers, e.g., NO, CO, CO2, NO2, CH4, HC, N2O and H2O. Both effects have been the major limitations of industrial SO2 emissions monitoring. The multi-channel gas analyzer measures 11 different wavelength channels simultaneously in order to achieve correction of several major problems of an infrared gas analyzer, including system drift, conflict of sensitivity, interferences among different infrared absorbers and limitation of measurement range. The optimized algorithm makes use of a 3rd polynomial rather than a constant factor to quantify gas-to-gas interference. The measurement results show good performance in both linear and nonlinear range, thereby solving the problem that the conventional interference correction is restricted by the linearity of both intended and interfering channels. The result implies that the measurement range of the developed multi-channel analyzer can be extended to the nonlinear absorption region. The measurement range and accuracy are evaluated by experimental laboratory calibration. An excellent agreement was achieved with a Pearson correlation coefficient (r2) of 0.99977 with measurement range from ~5 ppmv to 10 000 ppmv and measurement error <2 %. The instrument was also deployed for field measurement. Emissions from 3 different factories were measured. The emissions of these factories have been characterized with different co-existing infrared absorbers, covering a wide range of concentration levels. We compared our measurements with the commercial SO2 analyzers. The overall good agreements are achieved.

  9. Field test results with the targeted search MCSA. [multi-channel spectrum analyzer for SETI

    NASA Technical Reports Server (NTRS)

    Tarter, J. C.

    1988-01-01

    In April 1985, a 74,000 channel prototype of the multichannel spectrum analyzer (MCSA) that NASA plans to use in a systematic search for extraterrestrial intelligence (SETI) was installed at DSS13, a 26 meter R&D antenna facility at the Goldstone Deep Space Network (DSN) site. Since that time the instrumentation has been used to validate the performance of signal detection algorithms using locally injected signals and the weak carriers from distant spacecraft. This paper describes results from the Goldstone Field Tests and plans to move the prototype equipment to other sites where SETI may be conducted in the future.

  10. Confirmatory measurement experiences at the Savannah River Site using a portable multi-channel analyzer

    SciTech Connect

    Monson, R.W.; Jeffcoat, R.D.

    1993-01-01

    A continuing concern within the DOE complex is the control and accountability of special nuclear material. It is not enough to have a paper record of accountable material but it must be physically verified on a statistical sampling basis. The Material Control and Accountability section of the Westinghouse Savannah River Company has been developing a technique to confirm radioactive isotopes of interest in the field using a battery operated portable multichannel analyzer and a sodium iodide gamma probe detector. A description of the instrument and examples of actual confirmatory measurements at a variety of locations and environments will be presented.

  11. Analyzing the trade-off between multiple memory controllers and memory channels on multi-core processor performance

    SciTech Connect

    Sancho Pitarch, Jose Carlos; Kerbyson, Darren; Lang, Mike

    2010-01-01

    Increasing the core-count on current and future processors is posing critical challenges to the memory subsystem to efficiently handle concurrent memory requests. The current trend to cope with this challenge is to increase the number of memory channels available to the processor's memory controller. In this paper we investigate the effectiveness of this approach on the performance of parallel scientific applications. Specifically, we explore the trade-off between employing multiple memory channels per memory controller and the use of multiple memory controllers. Experiments conducted on two current state-of-the-art multicore processors, a 6-core AMD Istanbul and a 4-core Intel Nehalem-EP, for a wide range of production applications shows that there is a diminishing return when increasing the number of memory channels per memory controller. In addition, we show that this performance degradation can be efficiently addressed by increasing the ratio of memory controllers to channels while keeping the number of memory channels constant. Significant performance improvements can be achieved in this scheme, up to 28%, in the case of using two memory controllers with each with one channel compared with one controller with two memory channels.

  12. Confirmatory measurement experiences at the Savannah River Site using a portable multi-channel analyzer. Revision 1

    SciTech Connect

    Monson, R.W.; Jeffcoat, R.D.

    1993-07-01

    A continuing concern within the DOE complex is the control and accountability of special nuclear material. It is not enough to have a paper record of accountable material but it must be physically verified on a statistical sampling basis. The Material Control and Accountability section of the Westinghouse Savannah River Company has been developing a technique to confirm radioactive isotopes of interest in the field using a battery operated portable multichannel analyzer and a sodium iodide gamma probe detector. A description of the instrument and examples of actual confirmatory measurements at a variety of locations and environments will be presented.

  13. A computer program for analyzing channel geometry

    USGS Publications Warehouse

    Regan, R.S.; Schaffranek, R.W.

    1985-01-01

    The Channel Geometry Analysis Program (CGAP) provides the capability to process, analyze, and format cross-sectional data for input to flow/transport simulation models or other computational programs. CGAP allows for a variety of cross-sectional data input formats through use of variable format specification. The program accepts data from various computer media and provides for modification of machine-stored parameter values. CGAP has been devised to provide a rapid and efficient means of computing and analyzing the physical properties of an open-channel reach defined by a sequence of cross sections. CGAP 's 16 options provide a wide range of methods by which to analyze and depict a channel reach and its individual cross-sectional properties. The primary function of the program is to compute the area, width, wetted perimeter, and hydraulic radius of cross sections at successive increments of water surface elevation (stage) from data that consist of coordinate pairs of cross-channel distances and land surface or channel bottom elevations. Longitudinal rates-of-change of cross-sectional properties are also computed, as are the mean properties of a channel reach. Output products include tabular lists of cross-sectional area, channel width, wetted perimeter, hydraulic radius, average depth, and cross-sectional symmetry computed as functions of stage; plots of cross sections; plots of cross-sectional area and (or) channel width as functions of stage; tabular lists of cross-sectional area and channel width computed as functions of stage for subdivisions of a cross section; plots of cross sections in isometric projection; and plots of cross-sectional area at a fixed stage as a function of longitudinal distance along an open-channel reach. A Command Procedure Language program and Job Control Language procedure exist to facilitate program execution on the U.S. Geological Survey Prime and Amdahl computer systems respectively. (Lantz-PTT)

  14. The 8-million channel narrowband analyzer

    NASA Astrophysics Data System (ADS)

    Horowitz, P.; Forster, J.; Linscott, I.

    An 8.4 million channel narrowband spectrum analyzer is nearing completion, and will be used to expand the frequency coverage of the ongoing search at Oak Ridge by a factor of 200. The new system - project META - will cover 420 kHz at 0.05 Hz resolution, utilizing a swept receiver to cancel the effect of the earth's rotation. The increased bandwidth will permit observation of CW beacons transmitted at magic frequencies in any of three preferred frames: the local standard of rest, the galactic barycenter, and the cosmic blackbody rest frame.

  15. MULTI-CHANNEL ELECTRIC PULSE HEIGHT ANALYZER

    DOEpatents

    Gallagher, J.D. et al.

    1960-11-22

    An apparatus is given for converting binary information into coded decimal form comprising means, in combination with a binary adder, a live memory and a source of bigit pulses, for synchronizing the bigit pulses and the adder output pulses; a source of digit pulses synchronized with every fourth bigit pulse; means for generating a conversion pulse in response to the time coincidence of the adder output pulse and a digit pulse: means having a delay equal to two bigit pulse periods coupling the adder output with the memory; means for promptly impressing said conversion pulse on the input of said memory: and means having a delay equal to one bigit pulse period for again impressing the conversion pulse on the input of the memory whereby a fourth bigit adder pulse results in the insertion into the memory of second, third and fourth bigits.

  16. Multi-channel polarized thermal emitter

    DOEpatents

    Lee, Jae-Hwang; Ho, Kai-Ming; Constant, Kristen P

    2013-07-16

    A multi-channel polarized thermal emitter (PTE) is presented. The multi-channel PTE can emit polarized thermal radiation without using a polarizer at normal emergence. The multi-channel PTE consists of two layers of metallic gratings on a monolithic and homogeneous metallic plate. It can be fabricated by a low-cost soft lithography technique called two-polymer microtransfer molding. The spectral positions of the mid-infrared (MIR) radiation peaks can be tuned by changing the periodicity of the gratings and the spectral separation between peaks are tuned by changing the mutual angle between the orientations of the two gratings.

  17. Multi-Pass Quadrupole Mass Analyzer

    NASA Technical Reports Server (NTRS)

    Prestage, John D.

    2013-01-01

    Analysis of the composition of planetary atmospheres is one of the most important and fundamental measurements in planetary robotic exploration. Quadrupole mass analyzers (QMAs) are the primary tool used to execute these investigations, but reductions in size of these instruments has sacrificed mass resolving power so that the best present-day QMA devices are still large, expensive, and do not deliver performance of laboratory instruments. An ultra-high-resolution QMA was developed to resolve N2 +/CO+ by trapping ions in a linear trap quadrupole filter. Because N2 and CO are resolved, gas chromatography columns used to separate species before analysis are eliminated, greatly simplifying gas analysis instrumentation. For highest performance, the ion trap mode is used. High-resolution (or narrow-band) mass selection is carried out in the central region, but near the DC electrodes at each end, RF/DC field settings are adjusted to allow broadband ion passage. This is to prevent ion loss during ion reflection at each end. Ions are created inside the trap so that low-energy particles are selected by low-voltage settings on the end electrodes. This is beneficial to good mass resolution since low-energy particles traverse many cycles of the RF filtering fields. Through Monte Carlo simulations, it is shown that ions are reflected at each end many tens of times, each time being sent back through the central section of the quadrupole where ultrahigh mass filtering is carried out. An analyzer was produced with electrical length orders of magnitude longer than its physical length. Since the selector fields are sized as in conventional devices, the loss of sensitivity inherent in miniaturizing quadrupole instruments is avoided. The no-loss, multi-pass QMA architecture will improve mass resolution of planetary QMA instruments while reducing demands on the RF electronics for high-voltage/high-frequency production since ion transit time is no longer limited to a single pass. The

  18. Improving virtual channel discrimination in a multi-channel context.

    PubMed

    Srinivasan, Arthi G; Shannon, Robert V; Landsberger, David M

    2012-04-01

    Improving spectral resolution in cochlear implants is key to improving performance in difficult listening conditions (e.g. speech in noise, music, etc.). Current focusing might reduce channel interaction, thereby increasing spectral resolution. Previous studies have shown that combining current steering and current focusing reduces spread of excitation and improves virtual channel discrimination in a single-channel context. It is unclear whether the single-channel benefits from current focusing extend to a multi-channel context, in which the physical and perceptual interference of multiple stimulated channels might overwhelm the benefits of improved spectral resolution. In this study, signal discrimination was measured with and without current focusing, in the presence of competing stimuli on nearby electrodes. Results showed that signal discrimination was consistently better with current focusing than without, regardless of the amplitude of the competing stimuli. Therefore, combining current steering and current focusing may provide more effective spectral cues than are currently available. PMID:22616092

  19. Convergence of multi-channel effective interactions

    NASA Astrophysics Data System (ADS)

    Wagner, M.; Schaefer, B.-J.; Wambach, J.; Kuo, T. T. S.; Brown, G. E.

    2006-11-01

    A detailed analysis of the convergence properties of the Andreozzi-Lee-Suzuki iteration method, which is used for the calculation of low-momentum effective potentials Vlowk, is presented. After summarizing different modifications of the iteration method for one-flavor channels we introduce a simple model to study the generalization of the iteration method to multi-flavor channels. The failure of a straightforward generalization is discussed. The introduction of a channel-dependent cutoff cures the conceptual and technical problems. This novel method has already been applied successfully for realistic hyperon-nucleon interactions.

  20. Multi-channel electric aerosol spectrometer

    NASA Astrophysics Data System (ADS)

    Mirme, A.; Noppel, M.; Peil, I.; Salm, J.; Tamm, E.; Tammet, H.

    Multi-channel electric mobility spectrometry is a most efficient technique for the rapid measurement of an unstable aerosol particle size spectrum. The measuring range of the spectrometer from 10 microns to 10 microns is achieved by applying diffusional and field charging mechanisms simultaneously. On-line data processing is carried out with a microcomputer. Experimental calibration ensures correctness of measurement.

  1. Pre-experiment testing of the Multi Channel Systems 16-channel preamplifier CPA16

    SciTech Connect

    Patin, J B; Stoyer, M A; Moody, K J; Friensehner, A V

    2003-11-03

    The 16-channel preamplifier model CPA16 from Multi Channel Systems was studied. The CPA16 preamplifier/amplifier module is a candidate to be used as the preamplifiers and amplifiers for the focal plane detectors of the Mass Analyzer of Super Heavy Atoms (MASHA). The equipment used to test the CPA16, the results of testing the CPA16 with a pulser, a mixed {sup 229}Th/{sup 148}Gd source and a {sup 252}Cf source, and a summary of the results will be presented.

  2. Analyzing low frequency waves associated with plasma sheet flow channels

    NASA Astrophysics Data System (ADS)

    Xing, X.; Liang, J.; Wang, C. P.; Lyons, L. R.; Angelopoulos, V.

    2014-12-01

    Low frequency (0.006~0.02 Hz) magnetic oscillations are frequently observed to be associated with the substorm-related dipolarization in the near-Earth plasma sheet. It has been suggested that these oscillations are possibly triggered by ballooning instability in the transition region. However, our multi-point observations using THEMIS spacecraft have shown that similar oscillations are observed to be associated with the earthward moving flow channels as they penetrate from middle tail to the transition region. Linear MHD wave analysis suggested that these oscillations ahead of the dipolarization front are magnetosonic waves. For most of the cases, the thermal pressure and magnetic pressures variations are anti-phase, indicating slow mode waves. However, by taking advantage of the spacecraft located very close in X-Y plane and slightly away from the central plasma sheet, we found that for many events the phase relation between the thermal and magnetic pressure variations is Z-dependent, which suggests that the observational evidence for slow mode may not be applicable. In order to further examine these waves, we performed a MHD analysis in inhomogeneous plasma sheet. The calculation shows that for Harris Sheet configuration, the thermal and magnetic pressures variations can be anti-phase for any wave other than slow mode waves where the vertical velocity disturbance reaches its maximum, thus this phase relation may not be used as an identifier of magnetosonic wave modes. We will show the dispersion relation and wave generated disturbances obtained from the numerical calculations.

  3. Multi-channel multi-carrier generation using multi-wavelength frequency shifting recirculating loop.

    PubMed

    Li, Xinying; Yu, Jianjun; Dong, Ze; Zhang, Junwen; Shao, Yufeng; Chi, Nan

    2012-09-24

    We propose and experimentally demonstrate a novel scheme to generate optical frequency-locked multi-channel multi-carriers (MCMC), using a recirculating frequency shifter (RFS) loop based on multi-wavelength frequency shifting single side band (MWFS-SSB) modulation. In this scheme, optical subcarriers with multiple wavelengths can be generated each round. Furthermore, the generated MCMC are frequency- and phase-locked within each channel, and therefore can be effectively used for WDM superchannel. Dual-wavelength frequency shifting SSB modulation is carried out with dual-wavelength optical seed source in our experimental demonstration. Using this scheme, we successfully generate dual-channel multi-carriers, and one channel has 28 subcarriers while the other has 29 ones with 25-GHz subcarrier spacing. We also experimentally demonstrate that this kind of source can be used to carry 50-Gb/s optical polarization-division-multiplexing quadrature phase shift keying (PDM-QPSK) signal. PMID:23037333

  4. Multi-Channel Capacitive Sensor Arrays.

    PubMed

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  5. Multi-Channel Capacitive Sensor Arrays

    PubMed Central

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  6. Superchannel transmission system based on multi-channel equalization.

    PubMed

    Zeng, Tao

    2013-06-17

    We proposed a new method for superchannel transmission based on the newly proposed multi-channel equalization technique. This method allows us to realize tight channel spacing (equal to the baud rate) without using frequency-locked lasers and complex spectral shaping techniques at the transmitter. The inter-channel interference originated from the tight channel spacing is removed at the receiver by joint equalization of multiple adjacent channels. When the channel spacing is equal to the baud rate, our simulation results show that, with conventional oversample ratio (2 samples per symbol), realistic laser frequency offset and laser linewidth, the proposed multi-channel-equalization based method can achieve better performance than the traditional method using spectral shaping plus single channel equalization, although at the expense of a moderate increase in DSP complexity. The paper also gives a simple method to process the data after conventional chromatic dispersion compensation, which enables subsequent multi-channel equalization for long-haul transmissions. PMID:23787667

  7. Handling Deafness Problem of Scheduled Multi-Channel Polling MACs

    NASA Astrophysics Data System (ADS)

    Jiang, Fulong; Liu, Hao; Shi, Longxing

    Combining scheduled channel polling with channel diversity is a promising way for a MAC protocol to achieve high energy efficiency and performance under both light and heavy traffic conditions. However, the deafness problem may cancel out the benefit of channel diversity. In this paper, we first investigate the deafness problem of scheduled multi-channel polling MACs with experiments. Then we propose and evaluate two schemes to handle the deafness problem. Our experiment shows that deafness is a significant reason for performance degradation in scheduled multi-channel polling MACs. A proper scheme should be chosen depending on the traffic pattern and the design objective.

  8. Recent advances in Multi-Channel Algebraic Scattering

    SciTech Connect

    Karataglidis, S.; Fraser, P. R.; Amos, K.; Canton, L.; Pisent, G.; Svenne, J. P.; Knijff, D. van der

    2011-10-28

    For coupled-channel descriptions of low-energy nucleon-induced interactions involving nuclei with particle-unstable exited states, it is necessary to include the widths of the target states. How those widths may affect the elastic scattering cross sections is examined within the framework of the Multi-Channel Algebraic Scattering (MCAS) method.

  9. Tunable multi-channel terahertz wave power splitter

    NASA Astrophysics Data System (ADS)

    Jiu-Sheng, Li; Han, Liu; Le, Zhang

    2015-12-01

    The combination of terahertz technology and photonic crystal provides a new approach to realize compact terahertz wave devices. Relying on a conventional photonic crystal waveguide and photonic crystal surface-mode waveguides, a tunable multi-channel terahertz-wave power splitter is proposed. The mechanism of such a power splitter is further theoretically analyzed and numerically investigated with the aid of the plane-wave-expansion method and the finite-difference time-domain method. With an appropriate design, the proposed device can split the input terahertz wave energy equally into six output ports at the frequency of 0.6 THz. When changing the external magnetic field, the input terahertz wave can be equally divided into four output ports with the aid of a magnetic-sensitive material. Furthermore, the present device is very compact and the total size is of 4.4×6.0 mm2.

  10. Multi-dimensional PARAFAC2 component analysis of multi-channel EEG data including temporal tracking.

    PubMed

    Weis, Martin; Jannek, Dunja; Roemer, Florian; Guenther, Thomas; Haardt, Martin; Husar, Peter

    2010-01-01

    The identification of signal components in electroencephalographic (EEG) data originating from neural activities is a long standing problem in neuroscience. This area has regained new attention due to the possibilities of multi-dimensional signal processing. In this work we analyze measured visual-evoked potentials on the basis of the time-varying spectrum for each channel. Recently, parallel factor (PARAFAC) analysis has been used to identify the signal components in the space-time-frequency domain. However, the PARAFAC decomposition is not able to cope with components appearing time-shifted over the different channels. Furthermore, it is not possible to track PARAFAC components over time. In this contribution we derive how to overcome these problems by using the PARAFAC2 model, which renders it an attractive approach for processing EEG data with highly dynamic (moving) sources. PMID:21096263

  11. Dual-Channel Multi-Purpose Telescope

    NASA Technical Reports Server (NTRS)

    Howard, Joseph M.; Content, David

    2009-01-01

    A dual-channel telescope allows for a wide-field telescope design wit h a good, narrow field channel of fewer surfaces for shorter-wavelen gth or planet-finding applications. The design starts with a Korsch three-mirror-anastigmat (TMA) telescope that meets the mission criter ia for image quality over a wide field of view. The internal image a t the Cassegrain focus is typically blurry due to the aberration bala ncing among the three mirrors. The Cassegrain focus is then re-optim ized on the axis of the system where the narrow field channel instru ment is picked off by bending the primary mirror.

  12. A multi-channel waveform digitizer system

    SciTech Connect

    Bieser, F.; Muller, W.F.J. )

    1990-04-01

    The authors report on the design and performance of a multichannel waveform digitizer system for use with the Multiple Sample Ionization Chamber (MUSIC) Detector at the Bevalac. 128 channels of 20 MHz Flash ADC plus 256 word deep memory are housed in a single crate. Digital thresholds and hit pattern logic facilitate zero suppression during readout which is performed over a standard VME bus.

  13. Multi channel FM reflection profiler for buried pipeline surveying

    SciTech Connect

    Schock, S.G.; LeBlanc, L.R.

    1996-12-31

    A towed multi-channel FM acoustic reflection profiler has been developed for locating and generating images of buried objects. One significant application of this sonar is buried pipeline surveying. The multi-channel reflection profiler uses 16 line arrays mounted in a towed vehicle to determine the position and burial depth of an 18 inch steel pipe filled with concrete buried under 1.5 meters of sand. This sonar will allow a survey vessel to continuously track a buried pipeline providing a continuous record of pipe burial depth and position.

  14. Multi-channel fiber photometry for population neuronal activity recording

    PubMed Central

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-01-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals. PMID:26504642

  15. System design for a million channel digital spectrum analyzer /MCSA/. [of bandpass filtering in SETI receivers

    NASA Technical Reports Server (NTRS)

    Peterson, A.; Narasimha, M.; Narayan, S.

    1980-01-01

    The system design of a wideband (8 MHz) million-channel digital spectrum analyzer for use with a SETI receiver is presented. The analyzer makes use of a digital bandpass filter bank for transforming the wideband input signal into a specified number (120) of uniform narrowband output channels by the use of a Fourier transform digital processor combined with a prototype digital weighting network (finite impulse response filter). The output is then processed separately by 120 microprocessor-based discrete Fourier transform computers, each producing 8190 output channels of approximately 8 Hz bandwidth by the use of an 8190-point prime factor algorithm.

  16. Multi-channel medical imaging system

    DOEpatents

    Frangioni, John V.

    2016-05-03

    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in a subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  17. Multi-channel medical imaging system

    DOEpatents

    Frangioni, John V

    2013-12-31

    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in the subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  18. Instructional Design in Multi-Channel Learning System.

    ERIC Educational Resources Information Center

    Mukhopadhyay, Marmar; Parhar, Madhu

    2001-01-01

    Discusses instructional design and explains the multi-channel learning environment which was developed to allow the use of various media to provide alternative learning paths to accommodate differences in learning styles and media preferences. Highlights include taxonomies of learning; social aspects of learning; self-learning in distance…

  19. Design and Construction of an Autonomous Low-Cost Pulse Height Analyzer and a Single Channel Analyzer for Moessbauer Spectroscopy

    SciTech Connect

    Velasquez, A.A.; Trujillo, J.M.; Morales, A.L.; Tobon, J.E.; Gancedo, J.R.; Reyes, L.

    2005-04-26

    A multichannel analyzer (MCA) and a single channel-analyzer (SCA) for Moessbauer spectrometry application have been designed and built. Both systems include low-cost digital and analog components. A microcontroller manages, either in PHA or MCS mode, the data acquisition, data storage and setting of the pulse discriminator limits. The user can monitor the system from an external PC through the serial port with the RS232 communication protocol. A graphic interface made with the LabVIEW software allows the user to adjust digitally the lower and upper limits of the pulse discriminator, and to visualize as well as save the PHA spectra in a file. The system has been tested using a 57Co radioactive source and several iron compounds, yielding satisfactory results. The low cost of its design, construction and maintenance make this equipment an attractive choice when assembling a Moessbauer spectrometer.

  20. Faithful teleportation of multi-particle states involving multi spatially remote agents via probabilistic channels

    NASA Astrophysics Data System (ADS)

    Jiang, Min; Li, Hui; Zhang, Zeng-ke; Zeng, Jia

    2011-02-01

    We present an approach to faithfully teleport an unknown quantum state of entangled particles in a multi-particle system involving multi spatially remote agents via probabilistic channels. In our scheme, the integrity of an entangled multi-particle state can be maintained even when the construction of a faithful channel fails. Furthermore, in a quantum teleportation network, there are generally multi spatially remote agents which play the role of relay nodes between a sender and a distant receiver. Hence, we propose two schemes for directly and indirectly constructing a faithful channel between the sender and the distant receiver with the assistance of relay agents, respectively. Our results show that the required auxiliary particle resources, local operations and classical communications are considerably reduced for the present purpose.

  1. A calibration method of the multi-channel imaging lidar

    NASA Astrophysics Data System (ADS)

    Xu, Weiming; Liu, Jun; Shu, Rong

    2014-06-01

    We design a kind of imaging LiDAR with sixteen channels, which consists of a fiber laser source, dual scanning galvanometers, range measurement circuits and information processing circuits etc. The image LiDAR provides sixteen range measurements for one laser shot and the distance accuracy of each channel is about 4cm. This paper provides a calibrate method to correct point cloud images captured with the multi-channel LiDAR. The method needs to construct different slanted planes to cover the imaging field, and establish precise plane equations in the known ground coordinates, then fit planes with point clouds data and calculate correction parameters of all channels through the error model. The image accuracy is better than 5cm processed by this calibration method.

  2. Biomimetic Micropatterned Multi-channel Nerve Guides by Templated Electrospinning

    PubMed Central

    Jeffries, Eric; Wang, Yadong

    2012-01-01

    This report describes a new approach for fabricating micro-channels within three-dimensional electrospun constructs. These key features serve to mimic the fascicular architecture and fibrous extracellular matrix found in native nerve. Both electrospun fibers and multi-channeled structure nerve guides have become areas of increasing interest for their beneficial roles in nerve repair. However, to the best of our knowledge, this is the first report of a guide that incorporates both. Multiple parallel channels provide a greater number of defined paths and increased surface area compared to cylindrical guides. Additionally, the fibrous nature of electrospun fibers permits better mass transport than solid-walled constructs. The flexible fabrication scheme allows tailoring of nerve guide parameters such as channel diameters ranging from 33-176μm and various wall thicknesses. Channel and fiber structures were assessed by optical and electron microscope images. Geometric calculations estimated a porosity of over 85% for these guides with 16% or less from the channels. In vitro culture with Schwann cells demonstrated cellular infiltration into channels with restricted migration between fibers. Finally, cell proliferation and survival throughout the guide indicates that this design warrants future in vivo examination. PMID:22179932

  3. High transformer ratio of multi-channel dielectric wakefield structures

    NASA Astrophysics Data System (ADS)

    Shchelkunov, Sergey V.; Marshall, Thomas C.; Sotnikov, Gennadij V.; Hirshfield, Jay L.

    2016-09-01

    Dielectric wakefield (DWA) accelerator concepts are receiving attention on account of their promising performance, mechanical simplicity, and anticipated low cost. Interest in DWA physics directed toward an advanced high-gradient accelerator has been enhanced by a finding that some dielectrics can withstand very high fields (>1 GV/m) for the short times during the passage of charged bunches along dielectric-lined channels. In a two-channel structure, a drive bunch train propagates in a first channel, and in the second adjacent channel where a high gradient wakefield develops, a witness bunch is accelerated. Compared with single-channel DWA's, a two-beam accelerator delivers a high transformer ratio, and thereby reduces the number of drive beam sections needed to achieve a given final test beam energy. An overview of multi-channel DWA structures will be given, with an emphasis on two-channel structures, presenting their advantages and drawbacks, and potential impact on the field. Studies aimed to examine charging rate and charge distribution in a thin walled dielectric wakefield accelerator from a passing charge bunch and the physics of conductivity and discharge phenomena in dielectric materials useful for such accelerator applications are presented in a separate paper in the EAAC-2015 conference proceedings.

  4. Development of a Multi-Channel, High Frequency QRS Electrocardiograph

    NASA Technical Reports Server (NTRS)

    DePalma, Jude L.

    2003-01-01

    With the advent of the ISS era and the potential requirement for increased cardiovascular monitoring of crewmembers during extended EVAs, NASA flight surgeons would stand to benefit from an evolving technology that allows for a more rapid diagnosis of myocardial ischemia compared to standard electrocardiography. Similarly, during the astronaut selection process, NASA flight surgeons and other physicians would also stand to benefit from a completely noninvasive technology that, either at rest or during maximal exercise tests, is more sensitive than standard ECG in identifying the presence of ischemia. Perhaps most importantly, practicing cardiologists and emergency medicine physicians could greatly benefit from such a device as it could augment (or even replace) standard electrocardiography in settings where the rapid diagnosis of myocardial ischemia (or the lack thereof) is required for proper clinical decision-making. A multi-channel, high-frequency QRS electrocardiograph is currently under development in the Life Sciences Research Laboratories at JSC. Specifically the project consisted of writing software code, some of which contained specially-designed digital filters, which will be incorporated into an existing commercial software program that is already designed to collect, plot and analyze conventional 12-lead ECG signals on a desktop, portable or palm PC. The software will derive the high-frequency QRS signals, which will be analyzed (in numerous ways) and plotted alongside of the conventional ECG signals, giving the PC-viewing clinician advanced diagnostic information that has never been available previously in all 12 ECG leads simultaneously. After the hardware and software for the advanced digital ECG monitor have been fully integrated, plans are to use the monitor to begin clinical studies both on healthy subjects and on patients with known coronary artery disease in both the outpatient and hospital settings. The ultimate goal is to get the technology

  5. Analyzing isolated blood vessel contraction in multi-well plates.

    PubMed

    Borges, Ricardo; Díaz-Martín, David; Hernández-Jiménez, José G; Rodríguez-Valido, Manuel; Beltrán, Beatriz

    2016-05-01

    Organ baths have been successfully used for over a century to study the contractile or relaxation effects of drugs. Indeed, most of our understanding of vascular pharmacology is based on such in vitro studies. However, multiple parallel organ baths that require mechanical transduction consume relatively large amounts of drugs, gases, and buffers, and they take up a considerable bench space. In addition, such experiments have a high demand in terms of cost and animals, and the tissue preparation is labor intensive and slow. For these reasons, organ baths are no longer in the front line of industrial pharmacological research and they have almost disappeared from most academic laboratories. We have developed a very simple system, which can be implemented virtually in any laboratory, for the automatic analyses of rat aorta ring contraction based on optical methods and using multi-well plates. Rat aorta rings (≈0.5 mm wide) were situated in 96-multi-well plates, and the luminal vessel areas were continuously monitored using a USB camera driven by newly developed algorithms. Liquids were handled using multichannel pipettes, although these procedures can be automated for drug screening. The concentration-response curves obtained were similar to those reported in the literature using traditional force transduction techniques on isolated tissues. This system can also be used with other tissue preparations and for simultaneous fluorescence measurements. The new system described here offers a simple, cheap, and reliable alternative to the classic organ bath system. PMID:26905519

  6. Development of refined MCNPX-PARET multi-channel model for transient analysis in research reactors

    SciTech Connect

    Kalcheva, S.; Koonen, E.; Olson, A. P.

    2012-07-01

    Reactivity insertion transients are often analyzed (RELAP, PARET) using a two-channel model, representing the hot assembly with specified power distribution and an average assembly representing the remainder of the core. For the analysis of protected by the reactor safety system transients and zero reactivity feedback coefficients this approximation proves to give adequate results. However, a more refined multi-channel model representing the various assemblies, coupled through the reactivity feedback effects to the whole reactor core is needed for the analysis of unprotected transients with excluded over power and period trips. In the present paper a detailed multi-channel PARET model has been developed which describes the reactor core in different clusters representing typical BR2 fuel assemblies. The distribution of power and reactivity feedback in each cluster of the reactor core is obtained from a best-estimate MCNPX calculation using the whole core geometry model of the BR2 reactor. The sensitivity of the reactor response to power, temperature and energy distributions is studied for protected and unprotected reactivity insertion transients, with zero and non-zero reactivity feedback coefficients. The detailed multi-channel model is compared vs. simplified fewer-channel models. The sensitivities of transient characteristics derived from the different models are tested on a few reactivity insertion transients with reactivity feedback from coolant temperature and density change. (authors)

  7. Multi-input multi-output underwater communications over sparse and frequency modulated acoustic channels.

    PubMed

    Ling, Jun; Zhao, Kexin; Li, Jian; Nordenvaad, Magnus Lundberg

    2011-07-01

    This paper addresses multi-input multi-output (MIMO) communications over sparse acoustic channels suffering from frequency modulations. An extension of the recently introduced SLIM algorithm, which stands for sparse learning via iterative minimization, is presented to estimate the sparse and frequency modulated acoustic channels. The extended algorithm is referred to as generalization of SLIM (GoSLIM). The sparseness is exploited through a hierarchical Bayesian model, and because GoSLIM is user parameter free, it is easy to use in practical applications. Moreover this paper considers channel equalization and symbol detection for various MIMO transmission schemes, including both space-time block coding and spatial multiplexing, under the challenging channel conditions. The effectiveness of the proposed approaches is demonstrated using in-water experimental measurements recently acquired during WHOI09 and ACOMM10 experiments. PMID:21786895

  8. A duple watermarking strategy for multi-channel quantum images

    NASA Astrophysics Data System (ADS)

    Yan, Fei; Iliyasu, Abdullah M.; Sun, Bo; Venegas-Andraca, Salvador E.; Dong, Fangyan; Hirota, Kaoru

    2015-05-01

    Utilizing a stockpile of efficient transformations consisting of channel of interest, channel swapping, and quantum Fourier transforms, a duple watermarking strategy on multi-channel quantum images is proposed. It embeds the watermark image both into the spatial domain and the frequency domain of the multi-channel quantum carrier image, while also providing a quantum measurement-based algorithm to generate an unknown key that is used to protect the color information, which accompanies another key that is mainly used to scramble the spatial content of the watermark image in order to further safeguard the copyright of the carrier image. Simulation-based experiments using a watermark logo and nine building images as watermark image and carrier images, respectively, offer a duple protection for the copyright of carrier images in terms of the visible quality of the watermarked images. The proposed stratagem advances available literature in the quantum watermarking research field and sets the stage for the applications aimed at quantum data protection.

  9. Multi-carrier Communications over Time-varying Acoustic Channels

    NASA Astrophysics Data System (ADS)

    Aval, Yashar M.

    Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple

  10. HDTD: analyzing multi-tissue gene expression data

    PubMed Central

    Touloumis, Anestis; Marioni, John C.; Tavaré, Simon

    2016-01-01

    Motivation: By collecting multiple samples per subject, researchers can characterize intra-subject variation using physiologically relevant measurements such as gene expression profiling. This can yield important insights into fundamental biological questions ranging from cell type identity to tumour development. For each subject, the data measurements can be written as a matrix with the different subsamples (e.g. multiple tissues) indexing the columns and the genes indexing the rows. In this context, neither the genes nor the tissues are expected to be independent and straightforward application of traditional statistical methods that ignore this two-way dependence might lead to erroneous conclusions. Herein, we present a suite of tools embedded within the R/Bioconductor package HDTD for robustly estimating and performing hypothesis tests about the mean relationship and the covariance structure within the rows and columns. We illustrate the utility of HDTD by applying it to analyze data generated by the Genotype-Tissue Expression consortium. Availability and Implementation: The R package HDTD is part of Bioconductor. The source code and a comprehensive user’s guide are available at http://bioconductor.org/packages/release/bioc/html/HDTD.html. Contact: A.Touloumis@brighton.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27266441

  11. Science opportunity analyzer - a multi-mission tool for planning

    NASA Technical Reports Server (NTRS)

    Streiffert, B. A.; Polanskey, C. A.; O'Reilly, T.; Colwell, J.

    2002-01-01

    For many years the diverse scientific community that supports JPL's wide variety ofinterplanetary space missions has needed a tool in order to plan and develop their experiments. The tool needs to be easily adapted to various mission types and portable to the user community. The Science Opportunity Analyzer, SOA, now in its third year of development, is intended to meet this need. SOA is a java-based application that is designed to enable scientists to identify and analyze opportunities for science observations from spacecraft. It differs from other planning tools in that it does not require an in-depth knowledge of the spacecraft command system or operation modes to begin high level planning. Users can, however, develop increasingly detailed levels of design. SOA consists of six major functions: Opportunity Search, Visualization, Observation Design, Constraint Checking, Data Output and Communications. Opportunity Search is a GUI driven interface to existing search engines that can be used to identify times when a spacecraft is in a specific geometrical relationship with other bodies in the solar system. This function can be used for advanced mission planning as well as for making last minute adjustments to mission sequences in response to trajectory modifications. Visualization is a key aspect of SOA. The user can view observation opportunities in either a 3D representation or as a 2D map projection. The user is given extensive flexibility to customize what is displayed in the view. Observation Design allows the user to orient the spacecraft and visualize the projection of the instrument field of view for that orientation using the same views as Opportunity Search. Constraint Checking is provided to validate various geometrical and physical aspects of an observation design. The user has the ability to easily create custom rules or to use official project-generated flight rules. This capability may also allow scientists to easily impact the cost to science if

  12. Multi-channel compact optical zoom module by using microlenses

    NASA Astrophysics Data System (ADS)

    Liao, Wei-Hsiang; Su, Guo-Dung J.

    2015-09-01

    In this paper, we propose a multi-channel imaging system, which combines the principles of an insect's compound eye and optical zoom. We use the distance between two aspherical lenses to achieve zoom effect. In order to shrink the thickness of the system, we use the multi-channel structure which consists of curved micolens array. With this architecture, we can achieve the same effect like lens group. Each partial image passes through each channel separately and is stitched together at the image sensor. In our design, the thickness is 6.57 mm (wide), 6.25 mm (mid), 6.4 mm (tele) and the effective focal length is 2.2 mm( wide), 2.97 mm (mid), 4.04 mm (tele). Zoom ratio is close to 2 times. The size of image sensor is 6 mm in diameter. Due to the advance in microlens fabrication of microlens, this design has the potential to bed used inside mobile phone camera in future.

  13. Single and Multi-Channel Carbon-based Quantum Dragons

    NASA Astrophysics Data System (ADS)

    Inkoom, Godfred; Abdurazakov, Omadillo; Novotny, Mark

    2015-03-01

    In the coherent regime for electrical conductance measurements, two semi-infinite leads are connected to a finite nanostructure, and the nano-device conductance is calculated using the Landauer formula. Any channel k that has transmission for electrons with energy E, \\calTk (E) =1 contributes the conductance quantum G0 = 2e2 / h . Any nano-device with at least one \\calTk (E) =1 is called a quantum dragon. The transmission probability \\calTk (E) can be obtained from the solution of the time-independent Schrödinger equation. Uniform leads connected to armchair single-walled carbon nanotubes (SWCNTs) have calT (E) =1, while when connected to zigzag SWCNT the calT (E) is less than unity. Appropriately dimerized leads connected to zigzag SWCNTs are quantum dragons, while when connected to armchair SWCNTs calT (E) is less than unity. We have generalized the matrix method and mapping methods of in order to investigate SWCNTs that can be multi-channel quantum dragons. For example, one can use armchair SWCNT leads to connect to an armchair SWCNT to try to produce a multi-channel quantum dragon. Supported in part by NSF Grant DMR-1206233.

  14. Multi-ion pore behaviour in the CFTR chloride channel.

    PubMed

    Tabcharani, J A; Rommens, J M; Hou, Y X; Chang, X B; Tsui, L C; Riordan, J R; Hanrahan, J W

    1993-11-01

    Cystic fibrosis transmembrane conductance regulator (CFTR) is a non-rectifying, low-conductance channel regulated by ATP and phosphorylation, which mediates apical chloride conductance in secretory epithelia and malfunctions in cystic fibrosis (CF). Mutations at Lys 335 and Arg 347 in the sixth predicted transmembrane helix of CFTR alter its halide selectivity in whole-cell studies and its single channel conductance, but the physical basis of these alterations is unknown and permeation in CFTR is poorly understood. Here we present evidence that wild-type CFTR can contain more than one anion simultaneously. The conductance of CFTR passes through a minimum when channels are bathed in mixtures of two permeant anions. This anomalous mole fraction effect can be abolished by replacing Arg 347 with an aspartate and can be toggled on or off by varying the pH after the same residue is replaced with a histidine. Thus the CFTR channel should provide a convenient model in which to study multi-ion pore behaviour and conduction. The loss of multiple occupancy may explain how naturally occurring CF mutations at this site cause disease. PMID:7694154

  15. A multi-channel fiber optic proximity sensor

    NASA Astrophysics Data System (ADS)

    Kim, Byeong Kwon; Joo, Ki-Nam

    2016-03-01

    In this investigation, we propose an efficient multi-channel optical proximity sensor based on the spectrally-resolved interferometric principle. This sensor consists of a single optical source, a spectrometer and fiber optic components such as an optical circulator, a coarse wavelength division multiplexer (CWDM) and fiber optic probes. A spectrometer is used to detect the spectral interferograms of the measuring probes according to their own spectral bandwidths and the interference signals can be separated by the spectral filtering by a CWDM. The principle of the proposed sensor system was verified with feasibility experiments with the home-built 4 channel sensor system. The measuring range of each channel was 1 mm and the resolution was a few tens of nanometers determined by the deviation of linear motions. The stability of the sensor was less than 30 nm. With the aid of a broadband source and a spectrometer, the measurement channel can be extended further by using a suitable CWDM.

  16. Analysis of motion disambiguation using multi-channel circular SAR

    NASA Astrophysics Data System (ADS)

    Fasih, Ahmed R.; Rossler, Carl W.; Ash, Joshua N.; Moses, Randolph L.

    2010-04-01

    Combining moving target indication (MTI) radar with synthetic aperture radar (SAR) is of great interest to radar specialists, in terms of improving multiple-target tracking in large, urban scenes. A major obstacle to such a merger are ambiguities induced by mution. Using statistical bounds we quantify the improvement of moving target localization with multi-channel SAR over single-channel SAR and the more traditional MTI technique of displaced phase center array (DPCA) processing. We show that the potential for substantial improvements in localization performance is borne out by practical estimators based on sparse reconstruction algorithms, whose performance approach statistical bounds, even under clutter. We also outline a parallelization scheme for the nonquadratic regularized sparse reconstruction technique to utilize clusters for processing large datasets.

  17. JPL 2-to-the-20th-power channel 300 MHz bandwidth digital spectrum analyzer

    NASA Technical Reports Server (NTRS)

    Morris, G. A., Jr.; Wilck, H. C.

    1978-01-01

    A million (two to the 20th power) channel, 300 MHz bandwidth, digital spectrum analyzer was considered. The design, fabrication, and maintenance philosophy of the modular, pipelined, fast fourier transform (FFT) hardware are described. The spectrum analyzer will be used to examine the region from 1.4 GHz to 26 GHz for radio frequency interference which may be harmful to present and future tracking missions of the Deep Space Network. The design has application to the search for extraterrestrial intelligence signals and radio science phenomena.

  18. Photonic-assisted multi-channel compressive sampling based on effective time delay pattern.

    PubMed

    Liang, Yunhua; Chen, Minghua; Chen, Hongwei; Lei, Cheng; Li, Pengxiao; Xie, Shizhong

    2013-11-01

    In this paper, a photonic-assisted multi-channel compressive sampling scheme is proposed with one pseudo-random binary sequence (PRBS) source and Wavelength Division Multiplexing-based time delay. Meanwhile, the restricted isometry property of sensing matrix determined by the optimized time delay pattern is analyzed. In experiment, a four-channel photonic-assisted system with 5-GHz bandwidth was set up, where four-channel PRBS signals were generated by adding fiber-induced constant time delays to four-wavelength modulated PRBS signal, and a signal composed of twenty tones was recovered faithfully with four analog-to-digital converters (ADCs) with only 120-MHz-bandwidth. PMID:24216795

  19. Channel capacity and receiver deployment optimization for multi-input multi-output visible light communications.

    PubMed

    Wang, Jin-Yuan; Dai, Jianxin; Guan, Rui; Jia, Linqiong; Wang, Yongjin; Chen, Ming

    2016-06-13

    Multi-input multi-output (MIMO) technique is attractive for visible light communication (VLC), which exploits the high signal-to-noise ratio (SNR) of a single channel to overcome the capacity limitation due to the small modulation bandwidth of the light emitting diode. This paper establishes a MIMO VLC system under the non-negativity, peak power and dimmable average power constraints. Assume that perfect channel state information at the transmitter is known, the MIMO channel is changed to parallel, non-interfering sub-channels by using the singular value decomposition (SVD). Based on the SVD, the lower bound on the channel capacity for MIMO VLC is derived by employing entropy power inequality and variational method. Moreover, by maximizing the derived lower bound on the capacity under the given constraints, the receiver deployment optimization problem is formulated. The problem is solved by employing the principle of particle swarm optimization. Numerical results verify the derived capacity bound and the proposed deployment optimization scheme. PMID:27410325

  20. Multi-channel access technology based on wavelength division multiplexing in wireless UV communication mesh network

    NASA Astrophysics Data System (ADS)

    Zhao, Tai-fei; Zhang, Ai-li; Xue, Rong-li

    2013-05-01

    In this paper, the multi-channel access technology of wavelength division multiplexing (WDM) in the wireless ultraviolet (UV) scattering communication is studied. A multi-interface and multi-channel device is deployed in each UV transceiver node. The band-pass filter is configured in the receiving node so as to realize the multi-channel access by use of the UV WDM technology. Both the UV communication node model and the UV channel model are established. Three types of UV no-line-of-sight (NLOS) multi-channel communications are simulated in the mesh topologies with NS2. The results show that the UV multi-channel access technology can increase network throughput effectively with using WDM.

  1. The multi-channel laser focusing transceiver system and analysis of the image quality

    NASA Astrophysics Data System (ADS)

    Sui, Xin; Sun, Hongri; Yang, Kun; Qu, Zhou; Zhang, Bo; Cui, Yihan

    2015-10-01

    This paper has investigated and designed a multi-channel laser focusing transceiver system based on the combination of the laser technology, the space technology and the modern photoelectric detection technology which has the feather of wide wave band, non-chromatic aberration and high quality of image quality etc. The system could be synchronized and can change the distance of detection in a particular direction and obtain the image of atmospheric echo signals at different distances. In this paper we established a multi-channel and variable range laser focusing transceiver system that consists of a single-channel laser focusing transmitter system and a dual-channel receiving telescope system. The three channels of the system depend on the same reference axis. We propose a new method that is capable to improve the laser focusing transceiver system performance. The method is implemented by using parabolic reflector design in the primary and secondary mirror of the variable range laser focusing transmitter system, dual-channel off-axis design in the receiver system and simultaneous imaging design in the different regions of the same CCD target surface of the subsequent imaging system. The detection by two channels using off-axis design would be convenient for computing follow up information. On the base of theoretical basis of the reflective double mirror system and the theory Gaussian beam propagation, this paper calculates the actual converging sot size of the transmitter system and analyzes the wavefront aberration the defocus incidence. The oblique incidence will introduce the certain astigmatism and a small amount of coma and the defocus incidence will produce the certain coma and a small amount of spherical aberration and astigmatism. Finally, an experimental multi-channel laser focusing transceiver system was established and the image quality of the transceiver system on the base of wavefront aberrations, the spot diagram and the MTF curve of some fields is

  2. Analytical method for analyzing c-channel stiffener made of laminate composite

    NASA Astrophysics Data System (ADS)

    Kumton, Tattchapong

    Composite materials play the important role in the aviation industry. Conventional materials such as aluminum were replaced by composite material on the main structures. The objective of this study focuses on development of analytical method to analyze the laminated composite structure with C-channel cross-section. A lamination theory base closed-form solution was developed to analysis ply stresses on the C-channel cross-section. The developed method contains the effects of coupling due to unsymmetrical of both laminate and structural configuration levels. The present method also included the expression of the sectional properties such as centroid, axial and bending stiffnesses of cross-section. The results obtain from analytical method showed an excellent agreement with finite element results.

  3. High channel count and high precision channel spacing multi-wavelength laser array for future PICs.

    PubMed

    Shi, Yuechun; Li, Simin; Chen, Xiangfei; Li, Lianyan; Li, Jingsi; Zhang, Tingting; Zheng, Jilin; Zhang, Yunshan; Tang, Song; Hou, Lianping; Marsh, John H; Qiu, Bocang

    2014-01-01

    Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%. PMID:25488111

  4. High channel count and high precision channel spacing multi-wavelength laser array for future PICs

    PubMed Central

    Shi, Yuechun; Li, Simin; Chen, Xiangfei; Li, Lianyan; Li, Jingsi; Zhang, Tingting; Zheng, Jilin; Zhang, Yunshan; Tang, Song; Hou, Lianping; Marsh, John H.; Qiu, Bocang

    2014-01-01

    Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%. PMID:25488111

  5. Multi-channel time-reversal receivers for multi and 1-bit implementations

    DOEpatents

    Candy, James V.; Chambers, David H.; Guidry, Brian L.; Poggio, Andrew J.; Robbins, Christopher L.

    2008-12-09

    A communication system for transmitting a signal through a channel medium comprising digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. In one embodiment a transmitter is adapted to transmit the signal, a multiplicity of receivers are adapted to receive the signal, a digitizer digitizes the signal, and a time-reversal signal processor is adapted to time-reverse the digitized signal. An embodiment of the present invention includes multi bit implementations. Another embodiment of the present invention includes 1-bit implementations. Another embodiment of the present invention includes a multiplicity of receivers used in the step of transmitting the signal through the channel medium.

  6. Ground moving target indication via multi-channel airborne SAR

    NASA Astrophysics Data System (ADS)

    Vu, Duc; Guo, Bin; Xu, Luzhou; Li, Jian

    2011-06-01

    We consider moving target detection and velocity estimation for multi-channel synthetic aperture radar (SAR) based ground moving target indication (GMTI). Via forming velocity versus cross-range images, we show that small moving targets can be detected even in the presence of strong stationary ground clutter. Furthermore, the velocities of the moving targets can be estimated, and the misplaced moving targets can be placed back to their original locations based on the estimated velocities. An iterative adaptive approach (IAA), which is robust and user parameter free, is used to form velocity versus cross-range images for each range bin of interest. Moreover, we discuss calibration techniques to combat near-field coupling problems encountered in practical systems. Furthermore, we present a sparse signal recovery approach for stationary clutter cancellation. We conclude by demonstrating the effectiveness of our approaches by using the Air Force Research Laboratory (AFRL) publicly-released Gotcha airborne SAR based GMTI data set.

  7. Multi-channel detector readout method and integrated circuit

    DOEpatents

    Moses, William W.; Beuville, Eric; Pedrali-Noy, Marzio

    2004-05-18

    An integrated circuit which provides multi-channel detector readout from a detector array. The circuit receives multiple signals from the elements of a detector array and compares the sampled amplitudes of these signals against a noise-floor threshold and against one another. A digital signal is generated which corresponds to the location of the highest of these signal amplitudes which exceeds the noise floor threshold. The digital signal is received by a multiplexing circuit which outputs an analog signal corresponding the highest of the input signal amplitudes. In addition a digital control section provides for programmatic control of the multiplexer circuit, amplifier gain, amplifier reset, masking selection, and test circuit functionality on each input thereof.

  8. Multi-channel detector readout method and integrated circuit

    DOEpatents

    Moses, William W.; Beuville, Eric; Pedrali-Noy, Marzio

    2006-12-12

    An integrated circuit which provides multi-channel detector readout from a detector array. The circuit receives multiple signals from the elements of a detector array and compares the sampled amplitudes of these signals against a noise-floor threshold and against one another. A digital signal is generated which corresponds to the location of the highest of these signal amplitudes which exceeds the noise floor threshold. The digital signal is received by a multiplexing circuit which outputs an analog signal corresponding the highest of the input signal amplitudes. In addition a digital control section provides for programmatic control of the multiplexer circuit, amplifier gain, amplifier reset, masking selection, and test circuit functionality on each input thereof.

  9. Fast screening of rice knockout mutants by multi-channel microchip electrophoresis.

    PubMed

    Nan, He; Lee, Sang-Won; Kang, Seong Ho

    2012-08-15

    A multi-channel microchip electrophoresis (MC-ME) system with a laser-induced fluorescence detector was developed for the fast simultaneous detection of rice knockout mutants in genetically modified (GM) rice. In addition, three parallel separation channels were fabricated on a glass microchip to investigate the possibility of high-throughput screening of amplified-polymerase chain reaction products representing wild-type rice and mutants. The MC-ME system was developed to simultaneously record data on all channels using specifically designed electrodes for an even distribution of electric fields, an expanded laser beam for excitation, a 10× objective lens to capture emissions, and a charge coupled device camera for detection. Under a programmed electric field strength and a sieving gel matrix of 0.7% poly(ethylene oxide) (M(r)=8,000,000), T-DNA-inserted rice mutants, two standard wild-type rice lines, and six rice knockout mutants were analyzed within 4 min using three parallel channels on the microchip. Compared to conventional microchip electrophoresis, the MC-ME method is a valid and practical way to effectively analyze multiple samples in parallel for the identification of GM rice without any loss of resolving power or reproducibility. The MC-ME method was more than 15 times faster than traditional slab gel electrophoresis and proved to be a powerful tool for high-throughput screening of GM rice with high sensitivity, efficiency, and reproducibility. PMID:22841075

  10. 802.11s based multi-radio multi-channel mesh networking for fractionated spacecraft

    NASA Astrophysics Data System (ADS)

    Michel, Tony; Thapa, Bishal; Taylor, Steve

    802.11s is a new IEEE standard for mesh networking. It defines the protocols needed to build mobile ad hoc networks that operate over 802.11a, b, g and n waveforms running on inexpensive, and high performance commercial WiFi stations. We have developed a new capability to add to the 802.11s that uses multiple directional radio links that can operate simultaneously within a single mesh node. This is the basis of our multi-channel multi-radio mesh network used in the DARPA F6 program called F6Net. We have developed an analysis and emulation facility that lets us model the F6Net and evaluate the performance in a real world experimentation setup. This paper presents an “ Over-the-Air” experimentation testbed that uses standard Commercial Off-The-Shelf (COTS) 2.4GHz WiFi dongles in an indoor environment, and a shared-code simulation testbed that uses hardware simulated drivers within NS3's channel simulation facility to test 80211s network. To the best of our knowledge, this is the first work that provides a comprehensive evaluation platform with a full-fledged COTS hardware/software prototype to evaluate 802.11s network. Furthermore, we explain the design and development of multi-radio mesh extension for 802.11s that yields a robust and scalable mesh network suitable for clusters of LEO satellites.

  11. Multi-photon absorption in the channeling of electrons in an external field

    NASA Astrophysics Data System (ADS)

    Yaralov, V.

    2016-07-01

    Following the methods developed for atom ionization by alternating electric field the probability of multi-photon absorption of photons of the strong external laser field by channeled electron (extraction of electron from the channel) have been calculated for different strengths of the monochromatic external field. The emission spectra of 54 MeV electron channeled in diamond crystal planes (110) are shown for different values of the resonant laser field of a frequency close to the transition frequency in the channel taking into account multi-photon absorption. It is shown that the multi-photon phenomena give some contribution to the total level width.

  12. Multi-Channel Adjustable DC Power Supply with Single Transformer Based on Spectral Separation

    NASA Astrophysics Data System (ADS)

    Benfeng, Zhang; Huafeng, Li; Sunan, Li

    2014-01-01

    To meet the need of multi-channel DC power supply to activate multiple macro fiber composite (MFC) material simultaneously, a novel multi-channel adjustable DC supply using single-input single-output transformer based on spectral separation is proposed. A hybrid signal containing multiple frequency bands is boosted to obtain a high-voltage signal without bands change. Several frequency selection circuits are then used to separate individual signals in different frequency band from the high-voltage signal. Finally, these signals are rectified and filtered respectively to obtain multiple channel DC voltages. The feasibility of the proposed scheme is analyzed theoretically and verified by simulation. The hybrid signal containing multiple frequency bands is constructed by MCU (Micro Control Unit) and boosted using push-pull boost circuit. Low-pass, band-pass and high-pass frequency selection circuits are used to obtain the individual high-voltage signal in different frequency bands, and the amplitude frequency response characteristics of these filters are simulated using PSpice. Experimental results prove that each part of the scheme runs reliable and the output is stable and adjustable.

  13. Multi-channel transimpedance measurement of a planar electromagnetic sensor array

    NASA Astrophysics Data System (ADS)

    Chen, Dixiang; Xie, Ruifang; Zhou, Weihong; Hu, Hengjiang; Pan, Mengchun

    2015-02-01

    Planar electromagnetic sensor arrays have advantages such as nice coherence, fast response speed and high sensitivity, which can be used for micro damage inspection of crucial parts in equipment, and the key point in improving the inspection performance is to achieve a precise measurement of multi-channel transimpedances (the inductive voltages divided by the exciting current of the sensor). The principle and characteristics of planar electromagnetic sensor arrays are introduced in this paper, and a digital lock-in impedance measurement algorithm was investigated, with which the interference and noise in inductive voltage signals can be restrained effectively and the amplitude and phase of the transimpedance can be obtained with good repeatability. An eight channel impedance measurement system was established based on a field programmable gate array and utilized to inspect the micro damage in metal materials, and the experimental data were analyzed. The experimental results show that the impedance measurement has excellent repeatability when the sensor array is placed in air, and the maximum measurement error of the complete transimpedance measurement system is lower than 10%. A micro crack with a size of 1 mm (length) × 0.1 mm (width) × 1 mm (depth) can be detected through the measurement of multi-channel transimpedance in the planar electromagnetic sensor array.

  14. Stacked, filtered multi-channel X-ray diode array

    NASA Astrophysics Data System (ADS)

    MacNeil, L. P.; Dutra, E. C.; Compton, S. M.; Jacoby, B. A.; Raphaelian, M. L.

    2015-08-01

    There are many types of X-ray diodes that are used for X-ray flux or spectroscopic measurements and for estimating the spectral shape of the VUV to soft X-ray spectrum. However, a need arose for a low cost, robust X-ray diode to use for experiments in hostile environments on multiple platforms, and for experiments that utilize forces that may destroy the diode(s). Since the typical proposed use required a small size with a minimal single line-of-sight, a parallel array could not be used. So, a stacked, filtered multi-channel X-ray diode array was developed, called the MiniXRD. To achieve significant cost savings while maintaining robustness and ease of field setup, repair, and replacement, we designed the system to be modular. The filters were manufactured in-house and cover the range from 450 eV to 5000 eV. To achieve the line-of-sight accuracy needed, we developed mounts and laser alignment techniques. We modeled and tested elements of the diode design at NSTec Livermore Operations (NSTec / LO) to determine temporal response and dynamic range, leading to diode shape and circuitry changes to optimize impedance and charge storage. We fielded individual and stacked systems at several national facilities as ancillary `ride-along' diagnostics to test and improve the design usability. We present the MiniXRD system performance which supports consideration as a viable low-cost alternative for multiple-channel low-energy X-ray measurements. This diode array is currently at Technical Readiness Level (TRL) 6.

  15. Co-Production of Knowledge in Multi-Stakeholder Processes: Analyzing Joint Experimentation as Social Learning

    ERIC Educational Resources Information Center

    Akpo, Essegbemon; Crane, Todd A.; Vissoh, Pierre V.; Tossou, Rigobert C.

    2015-01-01

    Purpose: Changing research design and methodologies regarding how researchers articulate with end-users of technology is an important consideration in developing sustainable agricultural practices. This paper analyzes a joint experiment as a multi-stakeholder process and contributes to understand how the way of organizing social learning affects…

  16. Method of multi-channel data readout and acquisition

    DOEpatents

    Degtiarenko, Pavel V.; Popov, Vladimir E.

    2010-06-15

    A method for dealing with the problem of simultaneous continuous readout of large number of data channels from the set of multiple sensors in instances where the use of multiple amplitude-to-digital converters is not practical or causes undesirable extra noise and distortion in the data. The new method uses sensor front-end s and subsequent electronics to transform the analog input signals and encode them into a series of short pulses that can be transmitted to a long distance via a high frequency transmission line without information loss. Upon arrival at a destination data decoder and analyzer device, the series of short pulses can be decoded and transformed back, to obtain, store, and utilize the sensor information with the required accuracy.

  17. Quasiclassical theory of disordered multi-channel Majorana quantum wires

    NASA Astrophysics Data System (ADS)

    Neven, Patrick; Bagrets, Dmitry; Altland, Alexander

    2013-05-01

    Multi-channel spin-orbit quantum wires, when subjected to a magnetic field and proximity coupled to an s-wave superconductor, may support Majorana states. We study what happens to these systems in the presence of disorder. Inspired by the widely established theoretical methods of mesoscopic superconductivity, we develop á la Eilenberger a quasiclassical approach to topological nanowires valid in the limit of strong spin-orbit coupling. We find that the ‘Majorana number’ {\\cal M} , distinguishing between the state with Majorana fermions (symmetry class B) and no Majorana fermions (class D), is given by the product of two Pfaffians of gapped quasiclassical Green's functions fixed by the right and left terminals connected to the wire. A numerical solution of the Eilenberger equations reveals that the class D disordered quantum wires are prone to the formation of the zero-energy anomaly (class D impurity spectral peak) in the local density of states that shares the key features of the Majorana peak. In this way, we confirm the robustness of our previous conclusions (Bagrets and Altland 2012 Phys. Rev. Lett. 109 227005) on a more restrictive system setup. Generally speaking, we find that the quasiclassical approach provides a highly efficient means to address disordered class D superconductors both in the presence and in the absence of topological structures.

  18. Dynamic multi-channel TMS with reconfigurable coil.

    PubMed

    Jiang, Ruoli; Jansen, Ben H; Sheth, Bhavin R; Chen, Ji

    2013-05-01

    Investigations of the causal involvement of particular brain areas and interconnections in behavior require an external stimulation system with reasonable spatio-temporal resolution. Current transcranial magnetic stimulation (TMS) technology is limited to stimulating a single brain area once in a given trial. Here, we present a feasibility study for a novel TMS system based on multi-channel reconfigurable coils. With this hardware, researchers will be able to stimulate multiple brain sites in any temporal order in a trial. The system employs a wire-mesh coil, constructed using x- and y-directional wires. By varying the current direction and/or strength on each wire, we can configure the proposed mesh-wire coil into a standard loop coil and figure-eight coil of varying size. This provides maximum flexibility to the experimenter in that the location and extent of stimulation on the brain surface can be modified depending on experimental requirement. Moreover, one can dynamically and automatically modify the site(s) of stimulation several times within the span of seconds. By pre-storing various sequences of excitation patterns inside a control unit, one can explore the effect of dynamic TMS on behavior, in associative learning, and as rehabilitative therapy. Here, we present a computer simulation and bench experiments that show the feasibility of the dynamically-reconfigurable coil. PMID:23193321

  19. Direct Hydrocarbon Detection Using Multi-channel Transient Electromagnetics

    NASA Astrophysics Data System (ADS)

    Hobbs, B. A.; Ziolkowski, A. M.; Wright, D. A.

    We present a transient electromagnetic method for the detection of hydrocarbons and for monitoring their movement within a reservoir. Replacement of brine by gas or oil can cause a change in electrical resistivity of a porous rock of as much as 4 orders of magnitude. Seismic methods on the other hand are generally poor at detecting fluid content because the fluid content of a media has only a slight effect on its acoustic impedance. The data presented in this paper were collected as part of two Multi-channel Transient ElectroMagnetic (MTEM) surveys carried out in 1994 and 1996 over an underground gas storage reservoir at St. Illiers la Ville in France. The reservoir is a 30% porosity sandstone anticline about 30m thick at a depth of around 700m. In the summer gas is pumped in and the gas-water contact falls; in the winter gas is extracted and the gas- water contact rises. The position of the contact is known from constant monitoring at over 40 wells. The surveys had two objectives: first, to attempt to detect the reservoir directly from the data; second, to detect the movement of the gas water contact be- tween the 2 survey times. A recent breakthrough in the understanding of the system has allowed both these objectives to be achieved.

  20. Integrative analysis of T cell motility from multi-channel microscopy data using TIAM.

    PubMed

    Mayya, Viveka; Neiswanger, Willie; Medina, Ricardo; Wiggins, Chris H; Dustin, Michael L

    2015-01-01

    Integrative analytical approaches are needed to study and understand T cell motility as it is a highly coordinated and complex process. Several computational algorithms and tools are available to track motile cells in time-lapse microscopy images. In contrast, there has only been limited effort towards the development of tools that take advantage of multi-channel microscopy data and facilitate integrative analysis of cell-motility. We have implemented algorithms for detecting, tracking, and analyzing cell motility from multi-channel time-lapse microscopy data. We have integrated these into a MATLAB-based toolset we call TIAM (Tool for Integrative Analysis of Motility). The cells are detected by a hybrid approach involving edge detection and Hough transforms from transmitted light images. Cells are tracked using a modified nearest-neighbor association followed by an optimization routine to join shorter segments. Cell positions are used to perform local segmentation for extracting features from transmitted light, reflection and fluorescence channels and associating them with cells and cell-tracks to facilitate integrative analysis. We found that TIAM accurately captures the motility behavior of T cells and performed better than DYNAMIK, Icy, Imaris, and Volocity in detecting and tracking motile T cells. Extraction of cell-associated features from reflection and fluorescence channels was also accurate with less than 10% median error in measurements. Finally, we obtained novel insights into T cell motility that were critically dependent on the unique capabilities of TIAM. We found that 1) the CD45RO subset of human CD8 T cells moved faster and exhibited an increased propensity to attach to the substratum during CCL21-driven chemokinesis when compared to the CD45RA subset; and 2) attachment area and arrest coefficient during antigen-induced motility of the CD45A subset is correlated with surface density of integrin LFA1 at the contact. PMID:25445324

  1. Field experiments of multi-channel oceanographic fluorescence lidar for oil spill and chlorophyll- a detection

    NASA Astrophysics Data System (ADS)

    Li, Xiaolong; Zhao, Chaofang; Ma, Youjun; Liu, Zhishen

    2014-08-01

    A Multi-channel Oceanographic Fluorescence Lidar (MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll- a (Chl- a), has been developed using the Laser-induced Fluorescence (LIF) technique. The sketch of the MOFL system equipped with a compact multi-channel photomultiplier tube (MPMT) is introduced in the paper. The methods of differentiating the oil fluorescence from the background water fluorescence and evaluating the Chl- a concentration are described. Two field experiments were carried out to investigate the field performance of the system, i.e., an experiment in coastal areas for oil pollution detection and an experiment over the Yellow Sea for Chl- a monitoring. In the coastal experiment, several oil samples and other fluorescence substances were used to analyze the fluorescence spectral characteristics for oil identification, and to estimate the thickness of oil films at the water surface. The experiment shows that both the spectral shape of fluorescence induced from surface water and the intensity ratio of two channels ( I 495/ I 405) are essential to determine oil-spill occurrence. In the airborne experiment, MOFL was applied to measure relative Chl- a concentrations in the upper layer of the ocean. A comparison of relative Chl- a concentration measurements by MOFL and the Moderate Resolution Imaging Spectroradiometer (MODIS) indicates that the two datasets are in good agreement. The results show that the MOFL system is capable of monitoring oil spills and Chl- a in the upper layer of ocean water.

  2. 3.2Gbps multi-channel optical backplane bus demonstrator using photopolymer volume gratings

    NASA Astrophysics Data System (ADS)

    Bi, Hai; Choi, Jinho; Jiang, Wei; Han, Xuliang; Ellis, Jonathan; Chen, Ray T.

    2007-02-01

    A 3-slot optical backplane bus demonstrator based on glass substrate with photopolymer volume gratings array (PVGA) on top surface is built to allow 16 channels of data to be broadcast from central slot to two daughter slots or uploaded from any daughter slot to central slot. VCSELs and photodetectors packaged in the form of TO-46 can are assembled on top of each PVG and interleaved to reduce the crosstalk to below noise level. By carefully aligning the fabrication system, the incident angle deviation from Bragg condition is reduced to below 0.1° to maximize optical power delivery. The orientation and period of hologram fringes are uniform in the active area by collimating recording beams. Above 4.8Gbps aggregated data transmission is successfully demonstrated using the multi-channel system. Three computer mother boards using FPGA are made to verify the data transmission among the slots. Interface boards between the FPGA boards and optical transceivers are designed and fabricated to separate the implementation of digital layer and optical layer. Single channel transmissions with 3.2Gbps and even 10Gbps data rate are also tested with above 100uW input power, showing the potential to improve the total two-way bandwidth to above 102.4Gbps. Alignment tolerance of the optical interconnect system is investigated theoretically and experimentally. By analyzing the diffractive characteristics, the bandwidth limit of the optical layer is determined to be in the order of Terahertz. Design and fabrication issues are discussed for future optical backplane bus to make terahertz bandwidth into reality. Based on the experiments for Bit-interleaved Optical Backplane bus and Multi-channel optical backplane bus demonstrators, theoretical analysis of the bandwidth limit of the optical backplane bus using photopolymer volume gratings has been carried out.

  3. Continuous flow real-time PCR device using multi-channel fluorescence excitation and detection.

    PubMed

    Hatch, Andrew C; Ray, Tathagata; Lintecum, Kelly; Youngbull, Cody

    2014-02-01

    High throughput automation is greatly enhanced using techniques that employ conveyor belt strategies with un-interrupted streams of flow. We have developed a 'conveyor belt' analog for high throughput real-time quantitative Polymerase Chain Reaction (qPCR) using droplet emulsion technology. We developed a low power, portable device that employs LED and fiber optic fluorescence excitation in conjunction with a continuous flow thermal cycler to achieve multi-channel fluorescence detection for real-time fluorescence measurements. Continuously streaming fluid plugs or droplets pass through tubing wrapped around a two-temperature zone thermal block with each wrap of tubing fluorescently coupled to a 64-channel multi-anode PMT. This work demonstrates real-time qPCR of 0.1-10 μL droplets or fluid plugs over a range of 7 orders of magnitude concentration from 1 × 10(1) to 1 × 10(7). The real-time qPCR analysis allows dynamic range quantification as high as 1 × 10(7) copies per 10 μL reaction, with PCR efficiencies within the range of 90-110% based on serial dilution assays and a limit of detection of 10 copies per rxn. The combined functionality of continuous flow, low power thermal cycling, high throughput sample processing, and real-time qPCR improves the rates at which biological or environmental samples can be continuously sampled and analyzed. PMID:24297040

  4. Modeling of Multi-Scale Channeling Phenomena in Porous Flow

    NASA Astrophysics Data System (ADS)

    Räss, Ludovic; Omlin, Samuel; Yarushina, Viktoriya; Simon, Nina; Podladchikov, Yuri

    2015-04-01

    Predictive modeling of fluid percolation through tight porous rocks is critical to evaluate environmental risks associated with waste storage and reservoir operations. To understand the evolution of two-phase mixtures of fluid and solid it is insufficient to only combine single-phase fluid flow methods and solid mechanics. A proper coupling of these two different multi-scales physical processes is required to describe the complex evolution of permeability and porosity in space and in time. We conduct numerical modeling experiments in geometrically simple but physically complex systems of stressed rocks containing self-focusing porous flow. Our model is physically and thermodynamically consistent and describes the formation and evolution of fluid pathways. The model consists of a system of coupled equations describing poro-elasto-viscous deformation and flow. Nonlinearity of the solid rheology is also taken into account. We have developed a numerical application based on an iterative finite difference scheme that runs on mutli-GPUs cluster in parallel. In order to validate these models, we consider the largest CO2 sequestration project in operation at the Sleipner field in the Norwegian North Sea. Attempts to match the observations at Sleipner using conventional reservoir simulations fail to capture first order observations, such as the seemingly effortless vertical flow of CO2 through low permeability shale layers and the formation of focused flow channels or chimneys. Conducted high-resolution three-dimensional numerical simulations predict the formation of dynamically evolving high porosity and permeability pathways as a natural outcome of porous flow nonlinearly coupled with rock deformation, which may trigger leakage through low permeability barriers.

  5. Solving non-Markovian open quantum systems with multi-channel reservoir coupling

    SciTech Connect

    Broadbent, Curtis J.; Jing, Jun; Yu, Ting; Eberly, Joseph H.

    2012-08-15

    We extend the non-Markovian quantum state diffusion (QSD) equation to open quantum systems which exhibit multi-channel coupling to a harmonic oscillator reservoir. Open quantum systems which have multi-channel reservoir coupling are those in which canonical transformation of reservoir modes cannot reduce the number of reservoir operators appearing in the interaction Hamiltonian to one. We show that the non-Markovian QSD equation for multi-channel reservoir coupling can, in some cases, lead to an exact master equation which we derive. We then derive the exact master equation for the three-level system in a vee-type configuration which has multi-channel reservoir coupling and give the analytical solution. Finally, we examine the evolution of the three-level vee-type system with generalized Ornstein-Uhlenbeck reservoir correlations numerically. - Highlights: Black-Right-Pointing-Pointer The concept of multi-channel vs. single-channel reservoir coupling is rigorously defined. Black-Right-Pointing-Pointer The non-Markovian quantum state diffusion equation for arbitrary multi-channel reservoir coupling is derived. Black-Right-Pointing-Pointer An exact time-local master equation is derived under certain conditions. Black-Right-Pointing-Pointer The analytical solution to the three-level system in a vee-type configuration is found. Black-Right-Pointing-Pointer The evolution of the three-level system under generalized Ornstein-Uhlenbeck noise is plotted for many parameter regimes.

  6. W-state Analyzer and Multi-party Measurement-device-independent Quantum Key Distribution

    NASA Astrophysics Data System (ADS)

    Zhu, Changhua; Xu, Feihu; Pei, Changxing

    2015-12-01

    W-state is an important resource for many quantum information processing tasks. In this paper, we for the first time propose a multi-party measurement-device-independent quantum key distribution (MDI-QKD) protocol based on W-state. With linear optics, we design a W-state analyzer in order to distinguish the four-qubit W-state. This analyzer constructs the measurement device for four-party MDI-QKD. Moreover, we derived a complete security proof of the four-party MDI-QKD, and performed a numerical simulation to study its performance. The results show that four-party MDI-QKD is feasible over 150 km standard telecom fiber with off-the-shelf single photon detectors. This work takes an important step towards multi-party quantum communication and a quantum network.

  7. W-state Analyzer and Multi-party Measurement-device-independent Quantum Key Distribution.

    PubMed

    Zhu, Changhua; Xu, Feihu; Pei, Changxing

    2015-01-01

    W-state is an important resource for many quantum information processing tasks. In this paper, we for the first time propose a multi-party measurement-device-independent quantum key distribution (MDI-QKD) protocol based on W-state. With linear optics, we design a W-state analyzer in order to distinguish the four-qubit W-state. This analyzer constructs the measurement device for four-party MDI-QKD. Moreover, we derived a complete security proof of the four-party MDI-QKD, and performed a numerical simulation to study its performance. The results show that four-party MDI-QKD is feasible over 150 km standard telecom fiber with off-the-shelf single photon detectors. This work takes an important step towards multi-party quantum communication and a quantum network. PMID:26644289

  8. W-state Analyzer and Multi-party Measurement-device-independent Quantum Key Distribution

    PubMed Central

    Zhu, Changhua; Xu, Feihu; Pei, Changxing

    2015-01-01

    W-state is an important resource for many quantum information processing tasks. In this paper, we for the first time propose a multi-party measurement-device-independent quantum key distribution (MDI-QKD) protocol based on W-state. With linear optics, we design a W-state analyzer in order to distinguish the four-qubit W-state. This analyzer constructs the measurement device for four-party MDI-QKD. Moreover, we derived a complete security proof of the four-party MDI-QKD, and performed a numerical simulation to study its performance. The results show that four-party MDI-QKD is feasible over 150 km standard telecom fiber with off-the-shelf single photon detectors. This work takes an important step towards multi-party quantum communication and a quantum network. PMID:26644289

  9. A sophisticated, multi-channel data acquisition and processing system for high frequency noise research

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Bridges, James

    1992-01-01

    A sophisticated, multi-channel computerized data acquisition and processing system was developed at the NASA LeRC for use in noise experiments. This technology, which is available for transfer to industry, provides a convenient, cost-effective alternative to analog tape recording for high frequency acoustic measurements. This system provides 32-channel acquisition of microphone signals with an analysis bandwidth up to 100 kHz per channel. Cost was minimized through the use of off-the-shelf components. Requirements to allow for future expansion were met by choosing equipment which adheres to established industry standards for hardware and software. Data processing capabilities include narrow band and 1/3 octave spectral analysis, compensation for microphone frequency response/directivity, and correction of acoustic data to standard day conditions. The system was used successfully in a major wind tunnel test program at NASA LeRC to acquire and analyze jet noise data in support of the High Speed Civil Transport (HSCT) program.

  10. Load-Adaptive Practical Multi-Channel Communications in Wireless Sensor Networks

    PubMed Central

    Islam, Md. Shariful; Alam, Muhammad Mahbub; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs). In this paper, we present a multi-channel communications system for WSNs that is referred to as load-adaptive practical multi-channel communications (LPMC). LPMC estimates the active load of a channel at the sink since it has a more comprehensive view of the network behavior, and dynamically adds or removes channels based on the estimated load. LPMC updates the routing path to balance the loads of the channels. The nodes in a path use the same channel; therefore, they do not need to switch channels to receive or forward packets. LPMC has been evaluated through extensive simulations, and the results demonstrate that it can effectively increase the delivery ratio, network throughput, and channel utilization, and that it can decrease the end-to-end delay and energy consumption. PMID:22163685

  11. Load-adaptive practical multi-channel communications in wireless sensor networks.

    PubMed

    Islam, Md Shariful; Alam, Muhammad Mahbub; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs). In this paper, we present a multi-channel communications system for WSNs that is referred to as load-adaptive practical multi-channel communications (LPMC). LPMC estimates the active load of a channel at the sink since it has a more comprehensive view of the network behavior, and dynamically adds or removes channels based on the estimated load. LPMC updates the routing path to balance the loads of the channels. The nodes in a path use the same channel; therefore, they do not need to switch channels to receive or forward packets. LPMC has been evaluated through extensive simulations, and the results demonstrate that it can effectively increase the delivery ratio, network throughput, and channel utilization, and that it can decrease the end-to-end delay and energy consumption. PMID:22163685

  12. Least squares restoration of multi-channel images

    NASA Technical Reports Server (NTRS)

    Chin, Roland T.; Galatsanos, Nikolas P.

    1989-01-01

    In this paper, a least squares filter for the restoration of multichannel imagery is presented. The restoration filter is based on a linear, space-invariant imaging model and makes use of an iterative matrix inversion algorithm. The restoration utilizes both within-channel (spatial) and cross-channel information as constraints. Experiments using color images (three-channel imagery with red, green, and blue components) were performed to evaluate the filter's performance and to compare it with other monochrome and multichannel filters.

  13. Note: Design principles of a linear array multi-channel effusive metal-vapor atom source

    SciTech Connect

    Jana, B.; Majumder, A.; Thakur, K. B.; Das, A. K.

    2013-10-15

    Atomic beams can easily be produced by allowing atoms to effuse through a channel. In an earlier investigation [A. Majumder et al., Vacuum 83, 989 (2009)], we had designed, fabricated, and characterized an effusive metal-vapor source using collinear-array of multi-channel. In this note, we describe the theoretical basis of designing the source. Atom density in atomic beam has been estimated using a set of analytical expressions for long-channel operated in transparent mode. Parametric studies on aspect ratio of channel, inter-channel separation, beam width, and vertical distance from the source are carried out. They are useful in providing physical picture and optimizing design parameters.

  14. An Efficient VLSI Architecture for Multi-Channel Spike Sorting Using a Generalized Hebbian Algorithm

    PubMed Central

    Chen, Ying-Lun; Hwang, Wen-Jyi; Ke, Chi-En

    2015-01-01

    A novel VLSI architecture for multi-channel online spike sorting is presented in this paper. In the architecture, the spike detection is based on nonlinear energy operator (NEO), and the feature extraction is carried out by the generalized Hebbian algorithm (GHA). To lower the power consumption and area costs of the circuits, all of the channels share the same core for spike detection and feature extraction operations. Each channel has dedicated buffers for storing the detected spikes and the principal components of that channel. The proposed circuit also contains a clock gating system supplying the clock to only the buffers of channels currently using the computation core to further reduce the power consumption. The architecture has been implemented by an application-specific integrated circuit (ASIC) with 90-nm technology. Comparisons to the existing works show that the proposed architecture has lower power consumption and hardware area costs for real-time multi-channel spike detection and feature extraction. PMID:26287193

  15. Development of a Thermal/Optical Carbon Analyzer with Multi-Wavelength Capabilities

    NASA Astrophysics Data System (ADS)

    Sumlin, B.; Chow, J. C.; Watson, J. G.; Wang, X.; Gronstal, S.; Chen, L. W. A. A.; Trimble, D.

    2014-12-01

    A thermal/optical carbon analyzer (DRI Model 2015) equipped with a novel seven-wavelength light source (405, 445, 532, 635, 780, 808, and 980 nm) was developed to analyze chemical and optical properties of particles collected on quartz-fiber filters. Based on the DRI Model 2001 carbon analyzer at 633 nm, major modifications were made on mechanical and electrical components, flow control, and the carbon detector to adopt modern technologies, increase instrument reliability, and reduce costs and maintenance. The correlation between wavelength-dependent light attenuation and organic and elemental carbon (OC and EC, respectively) content allows estimation of the amount of brown and black carbon (BrC and BC, respectively) on filters. Continuous monitoring of the light reflected from and transmitted through the filter along with carbon evolved from the filter when heated to different temperatures under either inert or oxidizing gas environments provides insights into the optical properties of the carbon released from the filter; it also allows examination of the charring process as pyrolyzed char has been one of the major uncertainties in quantifying OC and EC. The objectives of this study are: 1) establish performance equivalency between the Model 2015 and Model 2001 DRI carbon analyzers when comparing similar laser wavelength to maintain consistency for long-term network sample analysis; and 2) analyze the multi-wavelength signal to quantify BrC and BC, and to optimize char correction. A selection of samples, including standard chemicals, rural and urban ambient filters, and emission sources from biomass burning, diesel and gasoline engine exhaust, and resuspended dust were measured by both the Model 2015 and Model 2001 analyzers. The instrument design, calibration, comparison with legacy analyzer, and interpretation of the multi-wavelengths measurement will be presented.

  16. [Optical multi-channel detection and analysis on solar ultra-violet irradiance spectrum].

    PubMed

    Zhao, Xiao-yan; He, Jie; Zuo, Hao-yi; Liang, Hui-min; Yang, Jing-guo

    2007-05-01

    The present paper reports a new type of ultraviolet CCD optical multi-channel analyzer and its application to detecting solar ultraviolet irradiance spectrum. Spectral detecting range of 200-1 100 nm, spectral resolution of 0.1 nm and detecting sensitivity of 0.02 lx were reached in this instrument. The solar spectra of UVB and UVA were measured in real time in Chengdu area. The measurement results have good correlation with the detection using normal solar ultraviolet irradiance detector. Primary analysis on the detection results of solar spectra in UVB and UVA indicated that in the morning and in the afternoon the irradiance of solar ultraviolet is smaller than that at noon, and reverse correlation holds for the change of SZA (Solar Zenith Angle). In different wavelength interval of UVA and UVB, generally, the radiation flux of long wavelength is greater than that of short. Clouds and aerosols in the atmosphere have important influence on ultraviolet irradiance. PMID:17655086

  17. Multi-channel optical sensor-array for measuring ballistocardiograms and respiratory activity in bed.

    PubMed

    Brüser, Christoph; Kerekes, Anna; Winter, Stefan; Leonhardt, Steffen

    2012-01-01

    Our work covers improvements in sensors and signal processing for unobtrusive, long-term monitoring of cardiac (and respiratory) rhythms using only non-invasive vibration sensors. We describe a system for the unobtrusive monitoring of vital signs by means of an array of novel optical ballistocardiography (BCG) sensors placed underneath a regular bed mattress. Furthermore, we analyze the systems spatial sensitivity and present proof-of-concept results comparing our system to a more conventional BCG system based on a single electromechanical-film (EMFi) sensor. Our preliminary results suggest that the proposed optical multi-channel system could have the potential to reduce beat-to-beat heart rate estimation errors, as well as enable the analysis of more complex breathing patterns. PMID:23367061

  18. An Efficient, Highly Flexible Multi-Channel Digital Downconverter Architecture

    NASA Technical Reports Server (NTRS)

    Goodhart, Charles E.; Soriano, Melissa A.; Navarro, Robert; Trinh, Joseph T.; Sigman, Elliott H.

    2013-01-01

    In this innovation, a digital downconverter has been created that produces a large (16 or greater) number of output channels of smaller bandwidths. Additionally, this design has the flexibility to tune each channel independently to anywhere in the input bandwidth to cover a wide range of output bandwidths (from 32 MHz down to 1 kHz). Both the flexibility in channel frequency selection and the more than four orders of magnitude range in output bandwidths (decimation rates from 32 to 640,000) presented significant challenges to be solved. The solution involved breaking the digital downconversion process into a two-stage process. The first stage is a 2 oversampled filter bank that divides the whole input bandwidth as a real input signal into seven overlapping, contiguous channels represented with complex samples. Using the symmetry of the sine and cosine functions in a similar way to that of an FFT (fast Fourier transform), this downconversion is very efficient and gives seven channels fixed in frequency. An arbitrary number of smaller bandwidth channels can be formed from second-stage downconverters placed after the first stage of downconversion. Because of the overlapping of the first stage, there is no gap in coverage of the entire input bandwidth. The input to any of the second-stage downconverting channels has a multiplexer that chooses one of the seven wideband channels from the first stage. These second-stage downconverters take up fewer resources because they operate at lower bandwidths than doing the entire downconversion process from the input bandwidth for each independent channel. These second-stage downconverters are each independent with fine frequency control tuning, providing extreme flexibility in positioning the center frequency of a downconverted channel. Finally, these second-stage downconverters have flexible decimation factors over four orders of magnitude The algorithm was developed to run in an FPGA (field programmable gate array) at input data

  19. A three-channel miniaturized optical system for multi-resolution imaging

    NASA Astrophysics Data System (ADS)

    Belay, Gebirie Y.; Ottevaere, Heidi; Meuret, Youri; Thienpont, Hugo

    2013-09-01

    Inspired by the natural compound eyes of insects, multichannel imaging systems embrace many channels that scramble their entire Field-Of-View (FOV). Our aim in this work was to attain multi-resolution capability into a multi-channel imaging system by manipulating the available channels to possess different imaging properties (focal length, angular resolution). We have designed a three-channel imaging system where the first and third channels have highest and lowest angular resolution of 0.0096° and 0.078° and narrowest and widest FOVs of 7° and 80°, respectively. The design of the channels has been done for a single wavelength of 587.6 nm using CODE V. The three channels each consist of 4 aspherical lens surfaces and an absorbing baffle that avoids crosstalk among the neighbouring channels. The aspherical lens surfaces have been fabricated in PMMA by ultra-precision diamond tooling and the baffles by metal additive manufacturing. The profiles of the fabricated lens surfaces have been measured with an accurate multi-sensor coordinate measuring machine and compared with the corresponding profiles of the designed lens surfaces. The fabricated lens profiles are then incorporated into CODE V to realistically model the three channels and also compare their performances with those of the nominal design. We can conclude that the performances of the two latter models are in a good agreement.

  20. Evaluation of Portable Multi-Gas Analyzers for use by Safety Personnel

    NASA Technical Reports Server (NTRS)

    Lueck, D. E.; Meneghelli, B. J.; Bardel, D. N.

    1998-01-01

    During confined space entry operations as well as Shuttle-safing operations, United Space Alliance (USA)/National Aeronautics and Space Administration (NASA) safety personnel use a variety of portable instrumentation to monitor for hazardous levels of compounds such as nitrogen dioxide (N%), monomethylhydrazine (NMM), FREON 21, ammonia (NH3), oxygen (O2), and combustibles (as hydrogen (H2)). Except for O2 and H2, each compound is monitored using a single analyzer. In many cases these analyzers are 5 to 10 years old and require frequent maintenance. In addition, they are cumbersome to carry and tend to make the job of personnel monitoring physically taxing. As part of an effort to upgrade the sensor technology background information was requested from a total of 27 manufacturers of portable multi-gas instruments. A set of criteria was established to determine which vendors would be selected for laboratory evaluation. These criteria were based on requests made by USA/NASA Safety personnel in order to meet requirements within their respective areas for confined-space and Shuttle-safing operations. Each of the 27 manufacturers of multi-gas analyzers was sent a copy of the criteria and asked to fill in the appropriate information pertaining to their instrumentation. Based on the results of the sensor criteria worksheets, a total of 9 vendors out of 27 surveyed manufacturers were chosen for evaluation. Each vendor included in the final evaluation process was requested to configure each of two analyzers with NO2, NH3, O2, and combustible sensors. A set of lab tests was designed in order to determine which of the multi-gas instruments under evaluation was best suited for use in both shuttle and confined space operations. These tests included linearity/repeatability, zero/span drift response/recovery, humidity, interference, and maintenance. At the conclusion of lab testing three vendors were selected for additional field testing. Based on the results of both the lab and

  1. A multi-channel high time resolution detector for high content imaging

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-10-01

    Medical imaging has long benefited from advances in photon counting detectors arising from space and particle physics. We describe a microchannel plate-based detector system for high content (multi-parametric) analysis, specifically designed to provide a step change in performance and throughput for measurements in imaged live cells and tissue for the 'omics'. The detector system integrates multi-channel, high time resolution, photon counting capability into a single miniaturized detector with integrated ASIC electronics, comprising a fast, low power amplifier discriminator and TDC for every channel of the discrete pixel electronic readout, and achieving a pixel density improvement of order two magnitudes compared with current comparable devices. The device combines high performance, easy reconfigurability, and economy within a compact footprint. We present simulations and preliminary measurements in the context of our ultimate goals of 20 ps time resolution with multi-channel parallel analysis (1024 channels).

  2. A Broadcast Channel Assignment Mechanism based on The Broadcast Tree for Multi-radio Multi-channel Wireless Mesh Networks

    NASA Astrophysics Data System (ADS)

    Xia, Yan; Zeng, Yingzhi

    2016-02-01

    This paper proposed a broadcast Channel Assignment Mechanism on base of optimized Broadcast Tree for wireless Mesh network (WMN), which is created by Branch and Bound Method. The simulations show that our algorithm not only reduces the broadcast redundancy but also avoids the potential channel interferences produced by unnecessary relay nodes.

  3. Deterministic Teleportation of Multi-qudit States in a Network via Various Probabilistic Channels

    NASA Astrophysics Data System (ADS)

    Zhang, Ti-Hang; Jiang, Min; Huang, Xu; Wan, Min

    2014-04-01

    In this paper, we present a generalized approach to faithfully teleport an unknown state of a multi-qudit system involving multi spatially remote agents via various probabilistic channels. In a quantum teleportation network, there are generally multi spatially remote relay agents between a sender and a distant receiver. With the assistance of the relay agents, it is possible to directly construct a deterministic channel between the sender and the distant receiver. In our scheme, different from previous probabilistic teleportation protocols, the integrity of the unknown multi-qudit state could be maintained even when the construction of faithful channel fails. Our results also show that the required auxiliary particle resources, local operations and classical communications are considerably reduced for the present purpose.

  4. Ion conduction in the KcsA potassium channel analyzed with a minimal kinetic model.

    PubMed

    Mafé, Salvador; Pellicer, Julio

    2005-02-01

    We use a model by Nelson to study the current-voltage and conductance-concentration curves of bacterial potassium channel KcsA without assuming rapid ion translocation. Ion association to the channel filter is rate controlling at low concentrations, but dissociation and transport in the filter can limit conduction at high concentration for ions other than K+. The absolute values of the effective rate constants are tentative but the relative changes in these constants needed to qualitatively explain the experiments should be of significance. PMID:15783362

  5. Partial flow compensation by transverse bypass configuration in multi-channel cryogenic compact heat exchanger

    NASA Astrophysics Data System (ADS)

    Jung, Jeheon; Hwang, Gyuwan; Baek, Seungwhan; Jeong, Sangkwon; Rowe, Andrew M.

    2012-01-01

    High-performance multi-channel heat exchangers are vulnerable to small defects such as ill-manufacture or contamination in flow channels. Even slight flow mal-distribution may result in drastic reduction of their thermal performance. In order to accommodate such performance reduction in multi-channel heat exchangers, transverse bypass structure among the channels of hot stream or cold stream is proposed. Since transverse bypass structure enables voluntary flow re-distribution among the channels, detrimental effect of flow defects can be partially reduced and flow mal-distribution can be locally relieved. The lower the flow resistance of transverse bypass is, the more substantial the flow re-distribution is and the larger its effect can be. Quantitative analysis and experimental verification on the effect of transverse bypass is carried out, and the results are presented in this paper.

  6. Using Electronic Properties of Adamantane Derivatives to Analyze their Ion Channel Interactions: Implications for Alzheimer's Disease

    NASA Astrophysics Data System (ADS)

    Bonacum, Jason

    2013-03-01

    The derivatives of adamantane, which is a cage-like diamondoid structure, can be used as pharmaceuticals for the treatment of various diseases and disorders such as Alzheimer's disease. These drugs interact with ion channels, and they act by electronically and physically hindering the ion transport. The electronic properties of each compound influence the location and level of ion channel hindrance, and the specific use of each compound depends on the functional groups that are attached to the adamantane base chain. Computational analysis and molecular simulations of these different derivatives and the ion channels can provide useful insight into the effect that the functional groups have on the properties of the compounds. Using this information, conclusions can be made about the pharmaceutical mechanisms, as well as how to improve them or create new beneficial compounds. Focusing on the electronic properties, such as the dipole moments of the derivatives and amino acids in the ion channels, can provide more efficient predictions of how these drugs work and how they can be enhanced. Department of Energy Grant DE-FG02-06ER46304

  7. Anomaly Detection using Multi-channel FLAC for Supporting Diagnosis of ECG

    NASA Astrophysics Data System (ADS)

    Ye, Jiaxing; Kobayashi, Takumi; Murakawa, Masahiro; Higuchi, Tetsuya; Otsu, Nobuyuki

    In this paper, we propose an approach for abnormality detection in multi-channel ECG signals. This system serves as front end to detect the irregular sections in ECG signals, where symptoms may be observed. Thereby, the doctor can focus on only the detected suspected symptom sections, ignoring the disease-free parts. Hence the workload of the inspection by the doctors is significantly reduced and the diagnosis efficiency can be sharply improved. For extracting the predominant characteristics of multi-channel ECG signals, we propose multi-channel Fourier local auto-correlations (m-FLAC) features on multi-channel complex spectrograms. The method characterizes the amplitude and phase information as well as temporal dynamics of the multi-channel ECG signal. At the anomaly detection stage, we employ complex subspace method for statistically modeling the normal (healthy) ECG patterns as in one-class learning. Then, we investigate the input ECG signals by measuring its deviation distance to the trained subspace. The ECG sections with disordered spectral distributions can be effectively discerned based on such distance metric. To validate the proposed approach, we conducted experiments on ECG dataset. The experimental results demonstrated the effectiveness of the proposed approach including promising performance and high efficiency, compared to conventional methods.

  8. Scale-Free Brain Quartet: Artistic Filtering of Multi-Channel Brainwave Music

    PubMed Central

    Wu, Dan; Li, Chaoyi; Yao, Dezhong

    2013-01-01

    To listen to the brain activities as a piece of music, we proposed the scale-free brainwave music (SFBM) technology, which translated scalp EEGs into music notes according to the power law of both EEG and music. In the present study, the methodology was extended for deriving a quartet from multi-channel EEGs with artistic beat and tonality filtering. EEG data from multiple electrodes were first translated into MIDI sequences by SFBM, respectively. Then, these sequences were processed by a beat filter which adjusted the duration of notes in terms of the characteristic frequency. And the sequences were further filtered from atonal to tonal according to a key defined by the analysis of the original music pieces. Resting EEGs with eyes closed and open of 40 subjects were utilized for music generation. The results revealed that the scale-free exponents of the music before and after filtering were different: the filtered music showed larger variety between the eyes-closed (EC) and eyes-open (EO) conditions, and the pitch scale exponents of the filtered music were closer to 1 and thus it was more approximate to the classical music. Furthermore, the tempo of the filtered music with eyes closed was significantly slower than that with eyes open. With the original materials obtained from multi-channel EEGs, and a little creative filtering following the composition process of a potential artist, the resulted brainwave quartet opened a new window to look into the brain in an audible musical way. In fact, as the artistic beat and tonal filters were derived from the brainwaves, the filtered music maintained the essential properties of the brain activities in a more musical style. It might harmonically distinguish the different states of the brain activities, and therefore it provided a method to analyze EEGs from a relaxed audio perspective. PMID:23717527

  9. Analyzing the benefit of optical transmission systems based on Root Raised Cosine PS-QPSK and a flexible channel grid.

    PubMed

    Seck, A; Ramantanis, P; Vuong, J; Bendimerad, D F; Lepers, C; Benkelfat, B-E; Frignac, Y

    2013-05-01

    We numerically investigate the multi-channel transmission performance of Polarization Switched Quadrature Phase Shift Keying (PS-QPSK) and we compare it to the performance of Polarization-Division-Multiplexed QPSK (PDM-QPSK), using Root Raised Cosine (RRC) spectral shaping, in the context of a flexible channel grid. We point out the impact of the roll-off factor and the potential influence of different dispersion compensation scenarios. Finally, the advantage of PS-QPSK against PDM-QPSK is presented as a function of the system parameters, while we also discuss the benefit of a RRC spectral shaping against a tight filtering at the transmitter side with a 2nd order super-Gaussian-shaped filter. PMID:23669907

  10. Analyzing Hydro-Geomorphic Responses in Post-Fire Stream Channels with Terrestrial LiDAR

    NASA Astrophysics Data System (ADS)

    Nourbakhshbeidokhti, S.; Kinoshita, A. M.; Chin, A.

    2015-12-01

    Wildfires have potential to significantly alter soil properties and vegetation within watersheds. These alterations often contribute to accelerated erosion, runoff, and sediment transport in stream channels and hillslopes. This research applies repeated Terrestrial Laser Scanning (TLS) Light Detection and Ranging (LiDAR) to stream reaches within the Pike National Forest in Colorado following the 2012 Waldo Canyon Fire. These scans allow investigation of the relationship between sediment delivery and environmental characteristics such as precipitation, soil burn severity, and vegetation. Post-fire LiDAR images provide high resolution information of stream channel changes in eight reaches for three years (2012-2014). All images are processed with RiSCAN PRO to remove vegetation and triangulated and smoothed to create a Digital Elevation Model (DEM) with 0.1 m resolution. Study reaches with two or more successive DEM images are compared using a differencing method to estimate the volume of sediment erosion and deposition. Preliminary analysis of four channel reaches within Williams Canyon and Camp Creek yielded erosion estimates between 0.035 and 0.618 m3 per unit area. Deposition was estimated as 0.365 to 1.67 m3 per unit area. Reaches that experienced higher soil burn severity or larger rainfall events produced the greatest geomorphic changes. Results from LiDAR analyses can be incorporated into post-fire hydrologic models to improve estimates of runoff and sediment yield. These models will, in turn, provide guidance for water resources management and downstream hazards mitigation.

  11. Multi-Channel Learning: A Note on Work in Progress.

    ERIC Educational Resources Information Center

    Anzalone, Stephen; And Others

    1995-01-01

    Examines multichannel learning, using learning channels such as teachers, to connect learners to knowledge, skills, and information found in the immediate learning environment and the community or delivered from a distance. Also discusses international use of multichannel learning as educational development in the Philippines and Haiti. (JMV)

  12. A robotic multi-channel platform for interstitial photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Sharikova, Anna V.; Finlay, Jarod C.; Dimofte, Andreea; Zhu, Timothy C.

    2013-03-01

    A custom-made robotic multichannel platform for interstitial photodynamic therapy (PDT) and diffuse optical tomography (DOT) was developed and tested in a phantom experiment. The system, which was compatible with the operating room (OR) environment, had 16 channels for independent positioning of light sources and/or isotropic detectors in separate catheters. Each channel's motor had an optical encoder for position feedback, with resolution of 0.05 mm, and a maximum speed of 5 cm/s. Automatic calibration of detector positions was implemented using an optical diode beam that defined the starting position of each motor, and by means of feedback algorithms controlling individual channels. As a result, the accuracy of zero position of 0.1 mm for all channels was achieved. We have also employed scanning procedures where detectors automatically covered the appropriate range around source positions. Thus, total scan time for a typical optical properties (OP) measurement throughout the phantom was about 1.5 minutes with point sources. The OP were determined based on the measured light fluence rates. These enhancements allow a tremendous improvement of treatment quality for a bulk tumor compared to the systems employed in previous clinical trials.

  13. Multi-qudit state sharing via various high-dimensional Bell channels

    NASA Astrophysics Data System (ADS)

    Wei, Yu-zhen; Jiang, Min

    2015-03-01

    In this paper, an innovative and efficient scheme is presented for multi-participants sharing arbitrary -qudit states with two-qudit maximally entangled Bell channels under the control of agents. After the sender (Alice) performs one GHZ-state measurement on her qudits, and each controller (all Bobs) makes a single-qudit measurement, the recipient (Charlie) only needs to operate a single-qudit unitary transformation based on the classical information from the sender and all controllers. This scheme is further expanded to deal with how to use non-maximally entangled Bell channels where an additional multi-qudit unitary operation is operated. Our result demonstrates that it is possible to share multi-qudit state under supervision with only two-qudit entangled Bell channels which makes it convenient in a practical application.

  14. THE 4-AMINOPYRIDINE IN VITRO EPILEPSY MODEL ANALYZED WITH A PERFORATED MULTI-ELECTRODE ARRAY

    PubMed Central

    Gonzalez-Sulser, Alfredo; Wang, Jing; Motamedi, Gholam K.; Avoli, Massimo; Vicini, Stefano; Dzakpasu, Rhonda

    2010-01-01

    Epileptiform discharges recorded in the 4-aminopyridine (4-AP) in vitro epilepsy model are mediated by glutamatergic and GABAergic signaling. Using a 60-channel perforated multi-electrode array (pMEA) on corticohippocampal slices from 2 to 3 week old mice we recorded interictal- and ictal-like events. When glutamatergic transmission was blocked, interictal-like events events no longer initiated in the hilus or CA3/CA1 pyramidal layers but originated from the dentate gyrus granule and molecular layers. Furthermore, frequencies of interictal-like events were reduced and durations were increased in these regions while cortical discharges were completely blocked. Following GABAA receptor blockade interictal-like events no longer propagated to the dentate gyrus while their frequency in CA3 increased; in addition, ictal-like cortical events became shorter while increasing in frequency. Lastly, drugs that affect tonic and synaptic GABAergic conductance modulate the frequency, duration, initiation and propagation of interictal-like events. These findings confirm and expand on previous studies indicating that multiple synaptic mechanisms contribute to synchronize neuronal network activity in forebrain structures. PMID:20955719

  15. Development of the Physical Structure of a Multi-Channel GNSS Signal Detector for Autonomous Coordination and Time Support of Artificial Earth Satellites

    NASA Astrophysics Data System (ADS)

    Shkol'nyi, V. N.; Suntsov, S. B.; Karaban, V. M.; Dmitriev, V. D.; Sheerman, F. I.

    2015-11-01

    Physical structure of a multi-channel detector of signals of global navigation satellite systems for autonomous coordination and time support of spacecrafts independent from the terrestrial infrastructure is analyzed. The parameters of multi-channel detector components are determined by mathematical modeling to achieve worldclass tactical and technical specifications. Technologies based on domestic 0.15 μm GaAs pHEMT (Closed JSC "Mikran," Tomsk) and 0.18 μm SiGe BiCMOS (JSC Research Institute of Molecular Electronics and "Mikron" Plant, Zelenograd) are taken for subsequent practical implementation in monolithic chip components of a navigation detector.

  16. Validity of a portable glucose, total cholesterol, and triglycerides multi-analyzer in adults.

    PubMed

    Coqueiro, Raildo da Silva; Santos, Mateus Carmo; Neto, João de Souza Leal; Queiroz, Bruno Morbeck de; Brügger, Nelson Augusto Jardim; Barbosa, Aline Rodrigues

    2014-07-01

    This study investigated the accuracy and precision of the Accutrend Plus system to determine blood glucose, total cholesterol, and plasma triglycerides in adults and evaluated its efficiency in measuring these blood variables. The sample consisted of 53 subjects (≥ 18 years). For blood variable laboratory determination, venous blood samples were collected and processed in a Labmax 240 analyzer. To measure blood variables with the Accutrend Plus system, samples of capillary blood were collected. In the analysis, the following tests were included: Wilcoxon and Student's t-tests for paired samples, Lin's concordance coefficient, Bland-Altman method, receiver operating characteristic curve, McNemar test, and k statistics. The results show that the Accutrend Plus system provided significantly higher values (p ≤ .05) of glucose and triglycerides but not of total cholesterol (p > .05) as compared to the values determined in the laboratory. However, the system showed good reproducibility (Lin's coefficient: glucose = .958, triglycerides = .992, total cholesterol = .940) and high concordance with the laboratory method (Lin's coefficient: glucose = .952, triglycerides = .990, total cholesterol = .944) and high sensitivity (glucose = 80.0%, triglycerides = 90.5%, total cholesterol = 84.4%) and specificity (glucose = 100.0%, triglycerides = 96.9%, total cholesterol = 95.2%) in the discrimination of high values of the three blood variables analyzed. It could be concluded that despite the tendency to overestimate glucose and triglyceride levels, a portable multi-analyzer is a valid alternative for the monitoring of metabolic disorders and cardiovascular risk factors. PMID:23871994

  17. The SRI24 Multi-Channel Brain Atlas

    PubMed Central

    Rohlfing, Torsten; Zahr, Natalie M.; Sullivan, Edith V.; Pfefferbaum, Adolf

    2009-01-01

    We present a new standard atlas of the human brain based on magnetic resonance images. The atlas was generated using unbiased population registration from high-resolution images obtained by multichannel-coil acquisition at 3T in a group of 24 normal subjects. The final atlas comprises three anatomical channels (T1-weighted, early and late spin echo), three diffusion-related channels (fractional anisotropy, mean diffusivity, diffusion-weighted image), and three tissue probability maps (CSF, gray matter, white matter). The atlas is dynamic in that it is implicitly represented by nonrigid transformations between the 24 subject images, as well as distortion-correction alignments between the image channels in each subject. The atlas can, therefore, be generated at essentially arbitrary image resolutions and orientations (e.g., AC/PC aligned), without compounding interpolation artifacts. We demonstrate in this paper two different applications of the atlas: (a) region definition by label propagation in a fiber tracking study is enabled by the increased sharpness of our atlas compared with other available atlases, and (b) spatial normalization is enabled by its average shape property. In summary, our atlas has unique features and will be made available to the scientific community as a resource and reference system for future imaging-based studies of the human brain. PMID:19183706

  18. Avian embryo monitoring during incubation using multi-channel diffuse speckle contrast analysis.

    PubMed

    Yeo, Chaebeom; Park, Hyun-Cheol; Lee, Kijoon; Song, Cheol

    2016-01-01

    Determining the survival rate of avian embryos during incubation is essential for cost-saving in the poultry industry. A multi-channel diffuse speckle contrast analysis (DSCA) system, comprising four optical fiber channels, is proposed to achieve noninvasive in vivo measurements of deep tissue flow. The system was able to monitor chick embryo vital signs over the entire incubation period. Moreover, it proved useful in distinguishing between chick embryos in healthy and weakened conditions. PMID:26819820

  19. Avian embryo monitoring during incubation using multi-channel diffuse speckle contrast analysis

    PubMed Central

    Yeo, Chaebeom; Park, Hyun-cheol; Lee, Kijoon; Song, Cheol

    2015-01-01

    Determining the survival rate of avian embryos during incubation is essential for cost-saving in the poultry industry. A multi-channel diffuse speckle contrast analysis (DSCA) system, comprising four optical fiber channels, is proposed to achieve noninvasive in vivo measurements of deep tissue flow. The system was able to monitor chick embryo vital signs over the entire incubation period. Moreover, it proved useful in distinguishing between chick embryos in healthy and weakened conditions. PMID:26819820

  20. Innovative RF Design Unites Benefits of Multiplexed and Multi-Channel System

    NASA Astrophysics Data System (ADS)

    Mavrič, Uroš

    2004-11-01

    The main advantages of the implemented innovative RF design are reproducibility, accuracy, low measurement uncertainty, and compact design. They were achieved by implementing the direct RF sampling and the completely new, patent pending technological approach of quasi-crossbar multiplexing and associated measurement method. The innovative quasi-crossbar switch matrix unites the benefits of both the multi-channel and the multiplexed system and at the same time compensates the disadvantages of the two. We achieve reproducibility and good "beam vs. current" dependence, which are multiplexed system characteristics and, using a multi-channel approach, we ensure a broader band of operation.

  1. Mitigation technique for receiver performance variation of multi-color channels in visible light communication.

    PubMed

    Uddin, Muhammad Shahin; Cha, Jae Sang; Kim, Jin Young; Jang, Yeong Min

    2011-01-01

    "Green" and energy-efficient wireless communication schemes have recently experienced rapid development and garnered much interest. One such scheme is visible light communication (VLC) which is being touted as one of the next generation wireless communication systems. VLC allows communication using multi-color channels that provide high data rates and illumination simultaneously. Even though VLC has many advantageous features compared with RF technologies, including visibility, ubiquitousness, high speed, high security, harmlessness for the human body and freedom of RF interference, it suffers from some problems on the receiver side, one of them being photo sensitivity dissimilarity of the receiver. The photo sensitivity characteristics of a VLC receiver such as Si photo-detector depend on the wavelength variation. The performance of the VLC receiver is not uniform towards all channel colors, but it is desirable for receivers to have the same performance on each color channel. In this paper, we propose a mitigation technique for reducing the performance variation of the receiver on multi-color channels. We show received power, SNR, BER, output current, and outage probability in our simulation for different color channels. Simulation results show that, the proposed scheme can reduce the performance variation of the VLC receiver on multi-color channels. PMID:22163946

  2. CO2-gradient measurements using a parallel multi-analyzer setup

    NASA Astrophysics Data System (ADS)

    Siebicke, L.; Steinfeld, G.; Foken, T.

    2011-03-01

    Accurate CO2 concentration gradient measurements are needed for the computation of advective flux terms, which are part of the full Net Ecosystem Exchange (NEE) budget equation. A typical draw back of current gradient measurement designs in advection research is the inadequate sampling of complex flow phenomena using too few observation points in space and time. To overcome this draw back, a new measurement design is presented which allows the parallel measurement of several sampling points at a high frequency. Due to the multi-analyzer nature of the design, inter-instrument bias becomes more of a concern compared to conventional setups. Therefore a statistical approach is presented which allows for accurate observations of concentration gradients, which are typically small in relation to analyzer accuracy, to be obtained. This bias correction approach applies a conditional, time dependent signal correction. The correction depends on a mixing index based on cross correlation analysis, which characterizes the degree of mixing of the atmosphere between individual sample points. The approach assumes statistical properties of probability density functions (pdf) of concentration differences between a sample point and the field average which are common to the pdf's from several sample points. The applicability of the assumptions made was tested by Large Eddy Simulation (LES) using the model PALM and could be verified for a test case of well mixed conditions. The study presents concentration time series before and after correction, measured at a 2 m height in the sub-canopy at the FLUXNET spruce forest site Waldstein-Weidenbrunnen (DE-Bay), analyzes the dependence of statistical parameters of pdf's from atmospheric parameters such as stratification, quantifies the errors and evaluates the performance of the bias correction approach. The improvements that are achieved by applying the bias correction approach are one order of magnitude larger than possible errors associated

  3. CO2-gradient measurements using a parallel multi-analyzer setup

    NASA Astrophysics Data System (ADS)

    Siebicke, L.; Steinfeld, G.; Foken, T.

    2010-10-01

    Accurate CO2 concentration gradient measurements are needed for the computation of advective flux terms, which are part of the full Net Ecosystem Exchange (NEE) budget equation. A typical draw back of current gradient measurement designs in advection research is the inadequate sampling of complex flow phenomena using too few observation points in space and time. To overcome this draw back, a new measurement design is presented which allows the parallel measurement of several sampling points at a high frequency. Due to the multi-analyzer nature of the design, inter-instrument bias becomes more of a concern compared to conventional setups. Therefore a statistical approach is presented which allows for accurate observations of concentration gradients, which are typically small in relation to analyzer accuracy, to be obtained. This bias correction approach applies a conditional, time dependent signal correction. The correction depends on a mixing index based on cross correlation analysis, which characterizes the degree of mixing of the atmosphere between individual sample points. The approach assumes statistical properties of probability density functions (pdf) of concentration differences between a sample point and the field average which are common to the pdf's from several sample points. The validity of the assumptions made was successfully verified by Large Eddy Simulation (LES) using the model PALM. The study presents concentration time series before and after correction, measured at a 2 m height in the sub-canopy at the FLUXNET spruce forest site Waldstein-Weidenbrunnen (DE-Bay), analyzes the dependence of statistical parameters of pdf's from atmospheric parameters such as stratification, quantifies the errors and evaluates the performance of the bias correction approach. The improvements that are achieved by applying the bias correction approach are one order of magnitude larger than possible errors associated with it, which is a strong incentive to use the

  4. Multi-Channel Electronically Scanned Cryogenic Pressure Sensor And Method For Making Same

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Holloway, Nancy M. (Inventor)

    2001-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multi-element array. These dies are bonded at specific sites on a glass, pre-patterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  5. Relaxation channels of multi-photon excited xenon clusters

    SciTech Connect

    Serdobintsev, P. Yu.; Melnikov, A. S.; Rakcheeva, L. P. Murashov, S. V.; Khodorkovskii, M. A.; Lyubchik, S.; Timofeev, N. A.; Pastor, A. A.

    2015-09-21

    The relaxation processes of the xenon clusters subjected to multi-photon excitation by laser radiation with quantum energies significantly lower than the thresholds of excitation of atoms and ionization of clusters were studied. Results obtained by means of the photoelectron spectroscopy method showed that desorption processes of excited atoms play a significant role in the decay of two-photon excited xenon clusters. A number of excited states of xenon atoms formed during this process were discovered and identified.

  6. Relaxation channels of multi-photon excited xenon clusters

    NASA Astrophysics Data System (ADS)

    Serdobintsev, P. Yu.; Rakcheeva, L. P.; Murashov, S. V.; Melnikov, A. S.; Lyubchik, S.; Timofeev, N. A.; Pastor, A. A.; Khodorkovskii, M. A.

    2015-09-01

    The relaxation processes of the xenon clusters subjected to multi-photon excitation by laser radiation with quantum energies significantly lower than the thresholds of excitation of atoms and ionization of clusters were studied. Results obtained by means of the photoelectron spectroscopy method showed that desorption processes of excited atoms play a significant role in the decay of two-photon excited xenon clusters. A number of excited states of xenon atoms formed during this process were discovered and identified.

  7. A Structured Approach to Analyze the Influence of Channel Dimensions on Heat Extraction via Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Bielert, E. R.; ten Kate, H. H. J.; Verweij, A. P.

    For the luminosity upgrade of the LHC at CERN, the final focusing quadrupole magnets will be exposed to an increased energy deposition in their coil windings. To have a higher heat transfer rate between cable and superfluid helium bath, the cable insulation has been subject of many studies. Improved cable insulation designs, making use of several layers of Kapton tape wound around Rutherford type cables, allow helium to penetrate via micro-channels, which are left open between adjacent Kapton tape sections. To better understand the thermal behaviour at operating temperatures below and some degrees above the helium lambda transition, besides experimental work, several numerical models have been developed to study the influence of the cable insulation. Here we present a new numerical model based on an earlier presented FEM model, which makes use of coupling variables such that the user can easily and quickly change the parameters of interest, giving the possibility to analyse new ideas effectively.

  8. Multi-channel rotating optical interface for data transmission

    NASA Technical Reports Server (NTRS)

    Ivie, C. V. (Inventor)

    1979-01-01

    Apparatus for transmitting multiple channels of data across a rotating interface, such as between an antenna that rotates with respect to a platform, is described. Features of the apparatus include: (1) light emitter elements and light detector elements located on the two bodies that rotate relative to each other; (2) a lens for focusing light from each emitter element onto a corresponding detector element; and (3) an image rotating means which is turned as one of the objects rotates, to derotate the images of the emitter elements that are to be focused on the detector elements.

  9. Spectrally shaped DP-16QAM super-channel transmission with multi-channel digital back-propagation.

    PubMed

    Maher, Robert; Xu, Tianhua; Galdino, Lidia; Sato, Masaki; Alvarado, Alex; Shi, Kai; Savory, Seb J; Thomsen, Benn C; Killey, Robert I; Bayvel, Polina

    2015-01-01

    The achievable transmission capacity of conventional optical fibre communication systems is limited by nonlinear distortions due to the Kerr effect and the difficulty in modulating the optical field to effectively use the available fibre bandwidth. In order to achieve a high information spectral density (ISD), while simultaneously maintaining transmission reach, multi-channel fibre nonlinearity compensation and spectrally efficient data encoding must be utilised. In this work, we use a single coherent super-receiver to simultaneously receive a DP-16QAM super-channel, consisting of seven spectrally shaped 10GBd sub-carriers spaced at the Nyquist frequency. Effective nonlinearity mitigation is achieved using multi-channel digital back-propagation (MC-DBP) and this technique is combined with an optimised forward error correction implementation to demonstrate a record gain in transmission reach of 85%; increasing the maximum transmission distance from 3190 km to 5890 km, with an ISD of 6.60 b/s/Hz. In addition, this report outlines for the first time, the sensitivity of MC-DBP gain to linear transmission line impairments and defines a trade-off between performance and complexity. PMID:25645457

  10. Spectrally Shaped DP-16QAM Super-Channel Transmission with Multi-Channel Digital Back-Propagation

    PubMed Central

    Maher, Robert; Xu, Tianhua; Galdino, Lidia; Sato, Masaki; Alvarado, Alex; Shi, Kai; Savory, Seb J.; Thomsen, Benn C.; Killey, Robert I.; Bayvel, Polina

    2015-01-01

    The achievable transmission capacity of conventional optical fibre communication systems is limited by nonlinear distortions due to the Kerr effect and the difficulty in modulating the optical field to effectively use the available fibre bandwidth. In order to achieve a high information spectral density (ISD), while simultaneously maintaining transmission reach, multi-channel fibre nonlinearity compensation and spectrally efficient data encoding must be utilised. In this work, we use a single coherent super-receiver to simultaneously receive a DP-16QAM super-channel, consisting of seven spectrally shaped 10GBd sub-carriers spaced at the Nyquist frequency. Effective nonlinearity mitigation is achieved using multi-channel digital back-propagation (MC-DBP) and this technique is combined with an optimised forward error correction implementation to demonstrate a record gain in transmission reach of 85%; increasing the maximum transmission distance from 3190 km to 5890 km, with an ISD of 6.60 b/s/Hz. In addition, this report outlines for the first time, the sensitivity of MC-DBP gain to linear transmission line impairments and defines a trade-off between performance and complexity. PMID:25645457

  11. Scalable Geiger/APD/PIN multi-channel sensing platform

    NASA Astrophysics Data System (ADS)

    Buckley, Steve; Bellis, Stephen; Wilcock, Reuben; Mathewson, Alan; Jackson, J. Carlton

    2006-02-01

    Previous generation low light detection platforms have been based on the photomultiplier tube (PMT) or the silicon single photon counting module (SPCM) from Perkin Elmer1. A new generation of silicon CMOS compatible photon counting sensors are being developed offering high quantum efficiency, low operating voltage, high levels of robustness and compatibility with CMOS processing for integration into large format imaging arrays. This latest generation yields a new detector for emerging applications which demand photon counting performance providing high performance and flexibility not possible to date. We describe a 4-channel photon detection platform, which allows the use of 4 separate photon counting detectors in either free space or fibre-coupled mode. The platform is scalable up to 16 channels with plug in modules allowing active quenching or Peltier cooling as required. A graphical user interface allows feedback and control of all device parameters. We show a novel ability to integrate separate detection modules to extend the dynamic range of the system. This allows a PIN or APD mode detector to be used alongside sensitive photon counting detectors. An advanced FPGA and microcontroller interface has been designed which allows simultaneous time binning of counting rates and readout of the analog signals when used with linear detectors. This new architecture will be discussed, presenting a full characterization of count rate, quantum efficiency, time binning and sensitivity across the broad spectrum of light flux applicable to PIN diodes, APDs and Geiger-mode photon counting sensors.

  12. Single and Multi-channel Quantum Dragons from Rectangular Nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Zhou; Novotny, Mark

    2015-03-01

    Recently quantum dragons have been discovered theoretically. Quantum dragons are nanostructures with correlated disorder that permit energy-independent total quantum transmission of electrons. Hence the electrical conductance G in a two-terminal measurement should be the conductance quantum G0 = 2e2 / h . The single-band tight banding model is used. An example of a single-channel quantum dragon is a rectangular nanotube with disorder along the direction z of the electron propagation. Quantum dragons are obtained by solving the time-independent Schrödinger equation to obtain the electrical transmission calT as a function of the incoming electron energy E. A quantum dragon has calT (E) =1 for all energies. This work generalizes the solution of the time-independent Schrödinger equation to the case of more than one open channel, and applies the method to nanotubes formed from rectangular lattices. One can envision such single-walled rectangular nanotubes for iron starting from free-standing single-atom-thick Fe membranes which have recently been obtained experimentally. Supported in part by NSF Grant DMR-1206233.

  13. Analyzing the Performance of Multi-Anode PMTs for the SoLID Project at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Haurie, Patrick

    2014-09-01

    As a part of their particle accelerator upgrade from 6 GeV to 12 GeV, Jefferson Lab is building a Solenoidal Large Intensity Device (SoLID). SoLID is a high rate and large acceptance particle detector containing multiple detectors including an electromagnetic calorimeter, and a large solenoidal magnet. Due to the large number of particles that need to be detected, SoLID needs a photomultiplier setup with high channel density. This research is to characterize the level of performance of Hamamatsu H10966 multi-anode Photomultiplier Tubes (PMTs) for the SoLID project. The two types of PMTs, multi-anode and single-anode, both have advantages and disadvantages. With higher channel density, multi-anode PMTs are more cost effective than single-anode, but it's not possible to control the relative gains of their channels. Single-anode PMTs have more control over their gain, but are easily affected by magnetic fields. We performed a uniformity scan of the multi-anode PMT, which is a measurement of the relative gain of each pixel to make sure the PMT works as the manufacturer specified. The next step was to measure the crosstalk across the PMT. This is the most important part of our research because it tells us if the PMT will be beneficial to the SoLID project.

  14. Designing Multi-Channel Web Frameworks for Cultural Tourism Applications: The MUSE Case Study.

    ERIC Educational Resources Information Center

    Garzotto, Franca; Salmon, Tullio; Pigozzi, Massimiliano

    A framework for the design of multi-channel (MC) applications in the cultural tourism domain is presented. Several heterogeneous interface devices are supported including location-sensitive mobile units, on-site stationary devices, and personalized CDs that extend the on-site experience beyond the visit time thanks to personal memories gathered…

  15. A Multi-Channel Approach for Collaborative Web-Based Learning

    ERIC Educational Resources Information Center

    Azeta, A. A.

    2008-01-01

    This paper describes an architectural framework and a prototype implementation of a web-based multi-channel e-Learning application that allows students, lecturers and the research communities to collaborate irrespective of the communication device a user is carrying. The application was developed based on the concept of "right once run on any…

  16. Self-adaptive method for high frequency multi-channel analysis of surface wave method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When the high frequency multi-channel analysis of surface waves (MASW) method is conducted to explore soil properties in the vadose zone, existing rules for selecting the near offset and spread lengths cannot satisfy the requirements of planar dominant Rayleigh waves for all frequencies of interest ...

  17. Multi-channel holographic birfurcative neural network system for real-time adaptive EOS data analysis

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Diep, J.; Huang, K.

    1991-01-01

    Viewgraphs on multi-channel holographic bifurcative neural network system for real-time adaptive Earth Observing System (EOS) data analysis are presented. The objective is to research and develop an optical bifurcating neuromorphic pattern recognition system for making optical data array comparisons and to evaluate the use of the system for EOS data classification, reduction, analysis, and other applications.

  18. Progress in multi-channel image fusion for face image matching

    NASA Astrophysics Data System (ADS)

    DelMarco, Stephen

    2013-05-01

    Fusion techniques have proven to be very useful for many signal and image processing applications including image recognition, image registration, and biometric matching. Along with standard fusion techniques, hypercomplex image processing techniques have been developed recently. These techniques represent a form of image fusion in which several image components are combined to form a multi-channel image. The multi-channel imagery may be processed using hypercomplex transforms, such as the hypercomplex Fourier transform, for image matching and registration. In this paper we investigate performance of multi-channel image fusion for face image matching. We use 3-D color face imagery and investigate fusion of various combinations of grayscale intensity, color, and range information. We conduct a theoretical investigation to identify conditions under which matchers using image channel fusion provide superior matching performance relative to matchers fusing single channel image matching results. We present numerical performance results in the form of Receiver Operating Characteristics curves quantifying matching performance for verification hypothesis testing problems.

  19. Enhanced channel estimation and symbol detection for high speed multi-input multi-output underwater acoustic communications.

    PubMed

    Ling, Jun; Yardibi, Tarik; Su, Xiang; He, Hao; Li, Jian

    2009-05-01

    The need for achieving higher data rates in underwater acoustic communications leverages the use of multi-input multi-output (MIMO) schemes. In this paper two key issues regarding the design of a MIMO communications system, namely, channel estimation and symbol detection, are addressed. To enhance channel estimation performance, a cyclic approach for designing training sequences and a channel estimation algorithm called the iterative adaptive approach (IAA) are presented. Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, the RELAX algorithm can be used to improve the IAA with BIC estimates further. Regarding symbol detection, a minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. Both simulated and experimental results are provided to validate the proposed MIMO scheme. RACE'08 experimental results employing a 4 x 24 MIMO system show that the proposed scheme enjoys an average uncoded bit error rate of 0.38% at a payload data rate of 31.25 kbps and an average coded bit error rate of 0% at a payload data rate of 15.63 kbps. PMID:19425650

  20. Self-aligned multi-channel silicon nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Zhu, Hao; Li, Qiliang; Yuan, Hui; Baumgart, Helmut; Ioannou, Dimitris E.; Richter, Curt A.

    2012-12-01

    Si nanowire field effect transistors (SiNW FETs) with multiple nanowire channels and different gate lengths have been fabricated by using a directed assembly approach combined with a standard photolithographic process. The electrical characteristics of SiNW FETs containing different numbers of nanowire channels were measured and compared. The multi-channel SiNW FETs show excellent performance: small subthreshold slope (≈75 mV/dec), large ON/OFF ratio (≈108), good break-down voltage (>30 V) and good carrier mobility (μp ≈ 100 cm2 V-1s-1). These excellent device properties were achieved by using a clean self-alignment process and an improved device structure with Schottky barriers at the source and drain contacts. Such high-performance multi-nanowire FETs are attractive for logic, memory, and sensor applications.

  1. Multi-channel millimeter wave image registration and segmentation for concealed object detection

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Su; Yeom, Seokwon; Son, Jung-Young; Kim, Shin-Hwan

    2010-04-01

    We address an image registration and segmentation method to detect concealed objects captured by passive millimeter wave (MMW) imaging. Passive MMW imaging can create interpretable imagery on the objects concealed under clothing. Due to the penetrating property of the MMW imaging, the MMW imaging system is often employed for the security and defense system. In this paper, we utilize a multi-channel PMMW imaging system operating at the 8 mm regime with linear polarization. Image registration and segmentation are performed to detect concealed objects under clothing. The registration is preceded to align different channel images by means of geometric feature extraction and a matching process. The Linde-Buzo-Gray (LBG) vector quantization with multi-channel information is adopted to segment the concealed object from the body area. In the experiment, the automated image registration and segmentation are performed with various concealed objects including a metal axe and a liquid container.

  2. Pairwise Quantum Discord for a Symmetric Multi-Qubit System in Different Types of Noisy Channels

    NASA Astrophysics Data System (ADS)

    Guo, You-Neng; Zeng, Ke; Wang, Guo-You

    2016-06-01

    We study the pairwise quantum discord (QD) for a symmetric multi-qubit system in different types of noisy channels, such as phase-flip, amplitude damping, phase-damping, and depolarizing channels. Using the QD and geometric quantum discord (GMQD) to quantify quantum correlations, some analytical and numerical results are presented. The results show that, the QD dynamics is strongly related to the number of spin particles N as well as the initial parameter 𝜃 of the one-axis twisting collective state. With the number of spin particles N increasing, the amount of the QD increases. However, when the amount of the QD arrives at a stable maximal value, the QD is independence of the number of spin particles N increasing. The behavior of the QD is symmetrical during a period 0 ≤ 𝜃 ≤ 2 π. Moreover, we compare the QD dynamics with the GMQD for a symmetric multi-qubit system in different types of noisy channels.

  3. Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

    PubMed

    Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

    2011-02-01

    In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time. PMID:21456152

  4. Theory and simulation of multi-channel interference (MCI) widely tunable lasers.

    PubMed

    Chen, Quanan; Lu, Qiaoyin; Guo, Weihua

    2015-07-13

    A novel design of an InP-based monolithic widely tunable laser, multi-channel interference (MCI) laser, is proposed and presented for the first time. The device is comprised of a gain section, a common phase section and a multi-channel interference section. The multi-channel interference section contains a 1x8 splitter based on cascaded 1 × 2 multi-mode interferometers (MMIs) and eight arms with unequal length difference. The rear part of each arm is integrated with a one-port multi-mode interference reflector (MIR). Mode selection of the MCI laser is realized by the constructive interference of the lights reflected back by the eight arms. Through optimizing the arm length difference, a tuning range of more than 40 nm covering the whole C band, a threshold current around 11.5 mA and an side-mode-suppression-ratio (SMSR) up to 48 dB have been predicted for this widely tunable laser. Detailed design principle and numerical simulation results are presented. PMID:26191863

  5. A multi-channel tunable source for atomic sensors

    NASA Astrophysics Data System (ADS)

    Bigelow, Matthew S.; Roberts, Tony D.; McNeil, Shirley A.; Hawthorne, Todd; Battle, Phil

    2015-09-01

    We have designed and completed initial testing on a laser source suitable for atomic interferometry from compact, robust, integrated components. Our design is enabled by capitalizing on robust, well-commercialized, low-noise telecom components with high reliability and declining costs which will help to drive the widespread deployment of this system. The key innovation is the combination of current telecom-based fiber laser and modulator technology with periodicallypoled waveguide technology to produce tunable laser light at rubidium D1 and D2 wavelengths (and expandable to other alkalis) using second harmonic generation (SHG). Unlike direct-diode sources, this source is immune to feedback at the Rb line eliminating the need for bulky high-power isolators in the system. In addition, the source has GHz-level frequency agility and in our experiments was found to only be limited by the agility of our RF generator. As a proof-of principle, the source was scanned through the Doppler-broadened Rb D2 absorption line. With this technology, multiple channels can be independently tuned to produce the fields needed for addressing atomic states in atom interferometers and clocks. Thus, this technology could be useful in the development cold-atom inertial sensors and gyroscopes.

  6. Development of a Multi-Channel Piezoelectric Acoustic Sensor Based on an Artificial Basilar Membrane

    PubMed Central

    Jung, Youngdo; Kwak, Jun-Hyuk; Lee, Young Hwa; Kim, Wan Doo; Hur, Shin

    2014-01-01

    In this research, we have developed a multi-channel piezoelectric acoustic sensor (McPAS) that mimics the function of the natural basilar membrane capable of separating incoming acoustic signals mechanically by their frequency and generating corresponding electrical signals. The McPAS operates without an external energy source and signal processing unit with a vibrating piezoelectric thin film membrane. The shape of the vibrating membrane was chosen to be trapezoidal such that different locations of membrane have different local resonance frequencies. The length of the membrane is 28 mm and the width of the membrane varies from 1 mm to 8 mm. Multiphysics finite element analysis (FEA) was carried out to predict and design the mechanical behaviors and piezoelectric response of the McPAS model. The designed McPAS was fabricated with a MEMS fabrication process based on the simulated results. The fabricated device was tested with a mouth simulator to measure its mechanical and piezoelectrical frequency response with a laser Doppler vibrometer and acoustic signal analyzer. The experimental results show that the as fabricated McPAS can successfully separate incoming acoustic signals within the 2.5 kHz–13.5 kHz range and the maximum electrical signal output upon acoustic signal input of 94 dBSPL was 6.33 mVpp. The performance of the fabricated McPAS coincided well with the designed parameters. PMID:24361926

  7. Developing fetal motor-cardiovascular coordination analyzed from multi-channel magnetocardiography.

    PubMed

    Schmidt, A; Schneider, U; Witte, O W; Schleußner, E; Hoyer, D

    2014-10-01

    Fetal movements (FM) related heart rate accelerations (AC) are an important maturation criterion. Since Doppler-based time resolution is not sufficient for accompanying heart rate variability analysis, the work is aimed at a comprehensive FM-AC analysis using magnetocardiographic recordings from fetuses during sleep.We identify FM and AC by independent component analysis and automatic recognition algorithms. We investigate associations between FM and AC of different magnitude by means of event coincidence and time series cross-correlation over the maturation period of 21-40 weeks of gestation (WGA).FM related AC appear with increasing AC magnitude and WGA. Vice versa, AC related FM appear independent of WGA, but more frequently with increasing AC amplitude. The FM-AC correlation exists already at 21 WGA and further increases with WGA while the variability of its time delay decreases. Hence, FM and AC are clearly associated over the whole investigated maturation period. The increase of FM related AC runs parallel to the increasing AC magnitude.The MCG methodology was confirmed and results from previous Doppler-based analyses reproduced. Hence, MCG recordings allow the collective analysis of heart rate variability based maturation indices and FM related AC. This synergism may improve the diagnosis of fetal developmental disorders. PMID:25229562

  8. A multi-channel clogging-resistant lab-on-a-chip cell counter and analyzer

    NASA Astrophysics Data System (ADS)

    Dai, Jie; Chiu, Yu-Jui; Lian, Ian; Wu, Tsung-Feng; Yang, Kecheng; Lo, Yu-Hwa

    2016-02-01

    Early signs of diseases can be revealed from cell detection in biofluids, such as detection of white blood cells (WBCs) in the peritoneal fluid for peritonitis. A lab-on-a-chip microfluidic device offers an attractive platform for such applications because of its small size, low cost, and ease of use provided the device can meet the performance requirements which many existing LoC devices fail to satisfy. We report an integrated microfluidic device capable of accurately counting low concentration of white blood cells in peritoneal fluid at 150 μl min-1 to offer an accurate (<3% error) and fast (~10 min/run) WBC count. Utilizing the self-regulating hydrodynamic properties and a unique architecture in the design, the device can achieve higher flow rate (500-1000 μl min-1), continuous running for over 5 h without clogging, as well as excellent signal quality for unambiguous WBC count and WBC classification for certain diseases. These properties make the device a promising candidate for point-of-care applications.

  9. The Radio JOVE Project: A New Multi-channel Spectrum Analyzer

    NASA Astrophysics Data System (ADS)

    Flagg, D.; Sky, J.; Reyes, F.; Thieman, J.; Higgins, C.

    2004-05-01

    A new radio spectrograph is now operational at the University of Florida Radio Observatory (UFRO) via the education and public outreach project called the Radio JOVE project(http://radiojove.gsfc.nasa.gov). The UFRO telescope is a 16-element 10-40 MHz log spiral array which is sensitive to both right-hand and left-hand circular polarization. Another spectrograph is connected to a 17-30 MHz log-periodic antenna located at Windward Community College in Hawaii (http://jupiter.wcc.hawaii.edu). Freely available software from Radio-Sky Publishing (http://www.radiosky.com) allows students, teachers, and radio astronomy enthusiasts to view the spectral data in real time via the Internet. Ultimately team members will be able to log on to the telescope and control the antenna and spectrometer's total sweep range, polarization, and calibrations. The software and telescope controls are discussed, and recent data results are shown. These data are of high quality and can lead to research applications.

  10. Non-cross talk multi-channel photomultiplier using guided electron multipliers

    DOEpatents

    Gomez, J.; Majewski, S.; Weisenberger, A.G.

    1995-09-26

    An improved multi-channel electron multiplier is provided that exhibits zero cross-talk and high rate operation. Resistive material input and output masks are employed to control divergence of electrons. Electron multiplication takes place in closed channels. Several embodiments are provided for these channels including a continuous resistive emissive multiplier and a discrete resistive multiplier with discrete dynode chains interspaced with resistive layers-masks. Both basic embodiments provide high gain multiplication of electrons without accumulating surface charges while containing electrons to their proper channels to eliminate cross-talk. The invention can be for example applied to improve the performance of ion mass spectrometers, positron emission tomography devices, in DNA sequencing and other beta radiography applications and in many applications in particle physics. 28 figs.

  11. Non cross talk multi-channel photomultiplier using guided electron multipliers

    DOEpatents

    Gomez, Javier; Majewski, Stanislaw; Weisenberger, Andrew G.

    1995-01-01

    An improved multi-channel electron multiplier is provided that exhibits zero cross-talk and high rate operation. Resistive material input and output masks are employed to control divergence of electrons. Electron multiplication takes place in closed channels. Several embodiments are provided for these channels including a continuous resistive emissive multiplier and a discrete resistive multiplier with discrete dynode chains interspaced with resistive layers-masks. Both basic embodiments provide high gain multiplication of electrons without accumulating surface charges while containing electrons to their proper channels to eliminate cross-talk. The invention can be for example applied to improve the performance of ion mass spectrometers, positron emission tomography devices, in DNA sequencing and other beta radiography applications and in many applications in particle physics.

  12. Multi-track single- and dual-channel plastic microchips for electrospray mass spectrometry.

    PubMed

    Leuthold, Luc Alexis; Reymond, Frédéric; Rossier, Joël S; Varesio, Emmanuel; Hopfgartner, Gérard

    2010-01-01

    Disposable plastic electrospray chips are particularly attractive for the automated analysis of organic compounds and organometallic compounds. Automated multi-track chip-based infusion electrospray mass spectrometry of low molecular weight compounds using an eight-channel plastic chip is presented. For that purpose, the commercial interface of a triple quadrupole linear ion trap was modified. A dual-channel plastic microchip, where two physically separated channels arrive very close to each other at the chip tip, was used to perform lock-mass accurate mass measurements on a quadrupole-time-of-flight instrument. The same chip was used to demonstrate the formation of an organometallic complex in solution on the chip tip. Furthermore, the potential to control the flow rate of each channel individually, which opens new possibilities in the study of supramolecular complexes, is discussed. PMID:20065514

  13. Content-Based Multi-Channel Network Coding Algorithm in the Millimeter-Wave Sensor Network.

    PubMed

    Lin, Kai; Wang, Di; Hu, Long

    2016-01-01

    With the development of wireless technology, the widespread use of 5G is already an irreversible trend, and millimeter-wave sensor networks are becoming more and more common. However, due to the high degree of complexity and bandwidth bottlenecks, the millimeter-wave sensor network still faces numerous problems. In this paper, we propose a novel content-based multi-channel network coding algorithm, which uses the functions of data fusion, multi-channel and network coding to improve the data transmission; the algorithm is referred to as content-based multi-channel network coding (CMNC). The CMNC algorithm provides a fusion-driven model based on the Dempster-Shafer (D-S) evidence theory to classify the sensor nodes into different classes according to the data content. By using the result of the classification, the CMNC algorithm also provides the channel assignment strategy and uses network coding to further improve the quality of data transmission in the millimeter-wave sensor network. Extensive simulations are carried out and compared to other methods. Our simulation results show that the proposed CMNC algorithm can effectively improve the quality of data transmission and has better performance than the compared methods. PMID:27376302

  14. Content-Based Multi-Channel Network Coding Algorithm in the Millimeter-Wave Sensor Network

    PubMed Central

    Lin, Kai; Wang, Di; Hu, Long

    2016-01-01

    With the development of wireless technology, the widespread use of 5G is already an irreversible trend, and millimeter-wave sensor networks are becoming more and more common. However, due to the high degree of complexity and bandwidth bottlenecks, the millimeter-wave sensor network still faces numerous problems. In this paper, we propose a novel content-based multi-channel network coding algorithm, which uses the functions of data fusion, multi-channel and network coding to improve the data transmission; the algorithm is referred to as content-based multi-channel network coding (CMNC). The CMNC algorithm provides a fusion-driven model based on the Dempster-Shafer (D-S) evidence theory to classify the sensor nodes into different classes according to the data content. By using the result of the classification, the CMNC algorithm also provides the channel assignment strategy and uses network coding to further improve the quality of data transmission in the millimeter-wave sensor network. Extensive simulations are carried out and compared to other methods. Our simulation results show that the proposed CMNC algorithm can effectively improve the quality of data transmission and has better performance than the compared methods. PMID:27376302

  15. High-throughput hyperpolarized 13C metabolic investigations using a multi-channel acquisition system

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyuk; Ramirez, Marc S.; Walker, Christopher M.; Chen, Yunyun; Yi, Stacey; Sandulache, Vlad C.; Lai, Stephen Y.; Bankson, James A.

    2015-11-01

    Magnetic resonance imaging and spectroscopy of hyperpolarized (HP) compounds such as [1-13C]-pyruvate have shown tremendous potential for offering new insight into disease and response to therapy. New applications of this technology in clinical research and care will require extensive validation in cells and animal models, a process that may be limited by the high cost and modest throughput associated with dynamic nuclear polarization. Relatively wide spectral separation between [1-13C]-pyruvate and its chemical endpoints in vivo are conducive to simultaneous multi-sample measurements, even in the presence of a suboptimal global shim. Multi-channel acquisitions could conserve costs and accelerate experiments by allowing acquisition from multiple independent samples following a single dissolution. Unfortunately, many existing preclinical MRI systems are equipped with only a single channel for broadband acquisitions. In this work, we examine the feasibility of this concept using a broadband multi-channel digital receiver extension and detector arrays that allow concurrent measurement of dynamic spectroscopic data from ex vivo enzyme phantoms, in vitro anaplastic thyroid carcinoma cells, and in vivo in tumor-bearing mice. Throughput and the cost of consumables were improved by up to a factor of four. These preliminary results demonstrate the potential for efficient multi-sample studies employing hyperpolarized agents.

  16. A high-throughput, multi-channel photon-counting detector with picosecond timing

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-06-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

  17. B0 mapping with multi-channel RF coils at high field.

    PubMed

    Robinson, Simon; Jovicich, Jorge

    2011-10-01

    Mapping the static magnetic field via the phase evolution over gradient echo scans acquired at two or more echo times is an established method. A number of possibilities exist, however, for combining phase data from multi-channel coils, denoising and thresholding field maps for high field applications. Three methods for combining phase images when no body/volume coil is available are tested: (i) Hermitian product, (ii) phase-matching over channels, and (iii) a new approach based on calculating separate field maps for each channel. The separate channel method is shown to yield field maps with higher signal-to-noise ratio than the Hermitian product and phase-matching methods and fewer unwrapping errors at low signal-to-noise ratio. Separate channel combination also allows unreliable voxels to be identified via the standard deviation over channels, which is found to be the most effective means of denoising field maps. Tests were performed using multichannel coils with between 8 and 32 channels at 3 T, 4 T, and 7 T. For application in the correction of distortions in echo-planar images, a formulation is proposed for reducing the local gradient of field maps to eliminate signal pile-up or swapping artifacts. Field maps calculated using these techniques, implemented in a freely available MATLAB toolbox, provide the basis for an effective correction for echo-planar imaging distortions at high fields. PMID:21608027

  18. Channel direction information probing for multi-antenna cognitive radio system

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Villardi, Gabriel Porto; Kojima, Fumihide; Yano, Hiroyuki

    2015-12-01

    This work studies the problem of channel direction information (CDI) probing for multi-antenna cognitive radio system. The CDI of the channel from the secondary transmitter (ST) to primary receiver (PR) is elementary information in designing the beamforming at the ST for mitigating the interference to the PR. However, lacking the explicit cooperation between primary and secondary systems, the CDI has to be acquired by probing at the ST, which is challenging. To solve this, we consider the line of sight (LoS) channel between the ST and the PR, and propose one CDI probing scheme for the ST. Specifically, the ST sends two types of probing signals by beamforming towards an interested region where both the secondary receiver (SR) and the PR are located and then actively learns the hidden feedback information from the primary system to acquire the CDI. The proposed scheme has a closed-form solution, and avoids the iteration between the probing and acquisition, which is desirable for practical system. Moreover, we show that the proposed probing scheme can be extended for primary systems working under multi-access channel and broadcasting channel. Simulation results demonstrate that the proposed scheme can improve the accuracy of the acquired CDI at the ST in cognitive ratio system remarkably.

  19. Development of a Multi-Channel Dielectric Resonator Oscillator for Space Communication Applications

    NASA Astrophysics Data System (ADS)

    Dennis, M. S.; Mysoor, N. R.; Cook, B. M.

    2005-08-01

    A novel multi-channel dielectric resonator oscillator (DRO) for Advanced Transponder use is developed for deep-space communication applications. The Advanced Transponder receives a 7.2-GHz (X-band) uplink signal and generates an 8.4-GHz (X-band) coherent or non-coherent downlink signal. The Advanced Transponder architecture incorporates two miniature DROs. These DROs are used in receiver and exciter frequency synthesis phase-locked loops (PLLs) in the Advanced Transponder. The DRO is capable of tuning over 27 Deep Space Network (DSN) X-band uplink channels (30 MHz). The DROs are designed with custom monolithic microwave integrated-circuit (MMIC) negative-resistance voltage-controlled oscillator chips. The receiver DRO design demonstrated a free-running single-sideband phase noise of -107 dBc/Hz at 100 kHz off the carrier frequency, a tuning linearity of +/- 3 percent over the channel locking range, and output power of +10 dBm +/-1 dB. Advantages of the multi-channel DRO include in-flight selection of transponder channel frequency, the enabling of novel mission operations techniques, frequency agility, and a single transponder design that will serve many missions and simplify hardware sparing strategies.

  20. Application of a multi-channel system for continuous monitoring and an early warning system.

    PubMed

    Lee, J H; Song, C H; Kim, B C; Gu, M B

    2006-01-01

    A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system. PMID:16722085

  1. Node localization via analyzing multi-path signals in ultrasonic sensor networks

    NASA Astrophysics Data System (ADS)

    Tomlinson, W. J.; Dong, B.; Lorenz, S.; Biswas, S.

    2014-05-01

    This paper proposes a novel signal analysis based node localization strategy for sensor networks used in structural health monitoring (SHM) applications. The key idea is to analyze location-dependent multipath signal patterns in inter-node ultrasonic signals, and use machine-learning mechanisms to detect such patterns for accurate node localization on metal substrates on target structures. Majority of the traditional mechanisms rely on radio based Time Delay of Arrival (TDOA), coupled with multilateration, and multiple reference nodes. The proposed mechanism attempts to solve the localization problem in an ultrasonic sensor network (USN), avoiding the use of multiple reference beacon nodes. Instead, it relies on signal analysis and multipath signature classification from a single reference node that periodically transmits ultrasonic localization beacons. The approach relies on a key observation that the ultrasonic signal received at any point on the structure from the reference node, is a superposition of the signals received on the direct path and through all possible multi-paths. It is hypothesized that if the location of the reference node and the substrate properties are known a-priori, it should be possible to train a receiver (source node), to identify its own location by observing the exact signature of the received signal. To validate this hypothesis, steps were taken to develop a TI MSP-430 based module for implementing a run-time system from a proposed architecture. Through extensive experimentation within an USN on the 2024 Aluminum substrate, it was demonstrated that localization accuracies up to 92% were achieved in the presence of varying spatial resolutions.

  2. Multi-channel PMMA microfluidic biosensor with integrated IDUAs for electrochemical detection

    PubMed Central

    Wongkaew, Nongnoot; He, Peng; Kurth, Vanessa; Surareungchai, Werasak; Baeumner, Antje J.

    2013-01-01

    A novel multi-channel poly(methyl methacrylate) (PMMA) microfluidic biosensor with interdigitated ultramicroelectrode arrays (IDUAs) for electrochemical detection was developed. The focus of the development was a simple fabrication procedure and the realization of a reliable large IDUA that can provide detection simultaneously to several microchannels. As proof of concept, five microchannels are positioned over a large single IDUA where the channels are parallel with the length of electrode finger. The IDUAs were fabricated on the PMMA cover piece and bonded to a PMMA substrate containing the microfluidic channels using UV/ozone-assisted thermal bonding. Conditions of device fabrication were optimized realizing a rugged large IDUA within a bonded PMMA device. Gold adhesion to the PMMA, protective coatings and pressure during bonding were optimized. Its electrochemical performance was studied using amperometric detection of potassium ferri and ferro hexacyanide. Cumulative signals within the same chip showed very good linearity over a range of 0 - 38 μM (R2 = 0.98) and a limit of detection of 3.48 μM. The bonding of the device was optimized so that no cross-talk between the channels was observed which otherwise would have resulted in unreliable electrochemical responses. The highly reproducible signals achieved were comparable to those obtained with separate single-channel devices. Subsequently, the multi-channel microfluidic chip was applied to a model bioanalytical detection strategy, i.e. the quantification of specific nucleic acid sequences using a sandwich approach. Here probe-coated paramagnetic beads and probe-tagged liposomes entrapping ferri/ferro hexacyanide as the redox marker were used to bind to a single stranded DNA sequence. Flow rates of the non-ionic detergent n-octyl-β-D-glucopyranoside (OG) for liposome lysis were optimized and the detection of the target sequences was carried out coulometrically within 250 s and with a limit of detection of 12

  3. A multi-channel readout electronics system for GEM and MICROMEGAS

    NASA Astrophysics Data System (ADS)

    Deng, Z.; Li, Y. L.; Gong, G. H.; Gong, H.; Luo, J.; Liu, Y. N.

    2009-11-01

    A multi-channel readout electronics system for GEM and MICROMEGAS has been developed. It consists of a front-end ASIC, a multi-channel ADC and a FPGA to sample the signal waveforms in real time. The gain of the front-end ASIC can be programmable from 1 mV/fC to 19 mV/fC and the output pulse width can be adjusted from 200 ns to 800 ns. The ENC is measured to be below 2000 e for Cin < 20 pF and below 5000 e for Cin < 60 pF. Detailed circuit performance and test results with detectors will be described in this paper.

  4. A high speed direct digital frequency synthesizer based on multi-channel structure

    NASA Astrophysics Data System (ADS)

    Ling, Yuan; Qiang, Zhang; Yin, Shi

    2015-06-01

    This paper presents a direct digital frequency synthesizer (DDFS) for high speed application based on multi-channel structure. This DDFS has phase resolution of 32 bits and magnitude resolution of 12 bits. In order to ensure the high speed and high resolution at the same time, the multi-channel sampling technique is used and a 12 bits linear digital-to-analog converter is implemented. The chip is fabricated in TSMC 130 nm CMOS technology with active area of 0.89 × 0.98 mm2 and total power consumption of 300 mW at a single 1.2 V supply voltage. The maximum operating speed is up to 2.0 GHz at room temperature.

  5. Characterizing phantom arteries with multi-channel laser ultrasonics and photo-acoustics.

    PubMed

    Johnson, Jami L; van Wijk, Kasper; Sabick, Michelle

    2014-03-01

    Multi-channel photo-acoustic and laser ultrasonic waves are used to sense the characteristics of proxies for healthy and diseased vessels. The acquisition system is non-contacting and non-invasive with a pulsed laser source and a laser vibrometer detector. As the wave signatures of our targets are typically low in amplitude, we exploit multi-channel acquisition and processing techniques. These are commonly used in seismology to improve the signal-to-noise ratio of data. We identify vessel proxies with a diameter on the order of 1 mm, at a depth of 18 mm. Variations in scattered and photo-acoustic signatures are related to differences in vessel wall properties and content. The methods described have the potential to improve imaging and better inform interventions for atherosclerotic vessels, such as the carotid artery. PMID:24412169

  6. An integrated analog O/E/O link for multi-channel laser neurons

    NASA Astrophysics Data System (ADS)

    Nahmias, Mitchell A.; Tait, Alexander N.; Tolias, Leonidas; Chang, Matthew P.; Ferreira de Lima, Thomas; Shastri, Bhavin J.; Prucnal, Paul R.

    2016-04-01

    We demonstrate an analog O/E/O electronic link to allow integrated laser neurons to accept many distinguishable, high bandwidth input signals simultaneously. This device utilizes wavelength division multiplexing to achieve multi-channel fan-in, a photodetector to sum signals together, and a laser cavity to perform a nonlinear operation. Its speed outpaces accelerated-time neuromorphic electronics, and it represents a viable direction towards scalable networking approaches.

  7. Integration of spatio-temporal contrast sensitivity with a multi-slice channelized Hotelling observer

    NASA Astrophysics Data System (ADS)

    Avanaki, Ali N.; Espig, Kathryn S.; Marchessoux, Cedric; Krupinski, Elizabeth A.; Bakic, Predrag R.; Kimpe, Tom R. L.; Maidment, Andrew D. A.

    2013-03-01

    Barten's model of spatio-temporal contrast sensitivity function of human visual system is embedded in a multi-slice channelized Hotelling observer. This is done by 3D filtering of the stack of images with the spatio-temporal contrast sensitivity function and feeding the result (i.e., the perceived image stack) to the multi-slice channelized Hotelling observer. The proposed procedure of considering spatio-temporal contrast sensitivity function is generic in the sense that it can be used with observers other than multi-slice channelized Hotelling observer. Detection performance of the new observer in digital breast tomosynthesis is measured in a variety of browsing speeds, at two spatial sampling rates, using computer simulations. Our results show a peak in detection performance in mid browsing speeds. We compare our results to those of a human observer study reported earlier (I. Diaz et al. SPIE MI 2011). The effects of display luminance, contrast and spatial sampling rate, with and without considering foveal vision, are also studied. Reported simulations are conducted with real digital breast tomosynthesis image stacks, as well as stacks from an anthropomorphic software breast phantom (P. Bakic et al. Med Phys. 2011). Lesion cases are simulated by inserting single micro-calcifications or masses. Limitations of our methods and ways to improve them are discussed.

  8. Development and demonstration of a multi-channel spheroidal focusing device for neutron beams

    NASA Astrophysics Data System (ADS)

    Hayashida, H.; Soyama, K.; Yamazaki, D.; Maruyama, R.; Yamamura, K.

    2014-07-01

    A multi-channel neutron focusing mirror is a compact device that can effectively enhance neutron intensity because the multi-channel structure can cover a large divergence of a neutron beam. In this study, we attempted to develop a compact multi-channel spheroidal (MS) neutron focusing device for two-dimensional focusing. A prototype of the MS mirror consists of three spheroidal mirrors of different diameters. The mirrors are fabricated through the copper plating method without supermirror coating and are aligned coaxially using ring-shaped spacers. The MS mirror was demonstrated at beam line 10 NOBORU port at J-PARC, which provides neutron beams with time-of-flight spectra. A gain factor of 6 in neutron intensity was obtained over wavelengths greater than 0.5 nm, and an imaging test with sample scanning could be performed with an exposure time of 10 s. A Gd-patterned standard sample was employed and a 2D image with a spatial resolution of 200 μm was successfully obtained.

  9. Design and application of multi-channel simultaneous detection system for well-earth potential

    NASA Astrophysics Data System (ADS)

    Lei, Shao; Jun, Lin; Wei, Jianrong; Sui, Yangyi; Wu, Ziyu

    2007-07-01

    Well-earth ERT (electrical resistance tomography) technology is an important geophysical exploration method which studies the location distribution of remaining oil. Based on virtual instrument technology, the author designs a set of multi-channel simultaneous detection system. It adopts multi-channel simultaneous sampling, bipolar and differential inputs, analog LPF (low pass filter), FIR digital filter, and linear accumulated digital averaging method or techniques to suppress electromagnetic noise and improve SNR (signal-to-noise ratio); uses digital signal process method to remove the overshoot, avoided huge errors and improved accuracy of measurement; adopts feedback compensative method to exclude the influence of SP(spontaneous potential) and cover a wide dynamic measurable scope; spectrum analysis method is used for judging all electrodes earthing situation correctly; the USB2.0 technique is used to solve the problem of bulky multi-channel data transmission to achieve high-speed data transmission between hardware and PC. The Liao He oilfield survey results show that the system is characterized with high efficiency, portable and strong antijiamming capability.

  10. Device for modular input high-speed multi-channel digitizing of electrical data

    DOEpatents

    VanDeusen, A.L.; Crist, C.E.

    1995-09-26

    A multi-channel high-speed digitizer module converts a plurality of analog signals to digital signals (digitizing) and stores the signals in a memory device. The analog input channels are digitized simultaneously at high speed with a relatively large number of on-board memory data points per channel. The module provides an automated calibration based upon a single voltage reference source. Low signal noise at such a high density and sample rate is accomplished by ensuring the A/D converters are clocked at the same point in the noise cycle each time so that synchronous noise sampling occurs. This sampling process, in conjunction with an automated calibration, yields signal noise levels well below the noise level present on the analog reference voltages. 1 fig.

  11. Spectrally resolved multi-channel contributions to the harmonic emission in N2

    NASA Astrophysics Data System (ADS)

    Diveki, Z.; Camper, A.; Haessler, S.; Auguste, T.; Ruchon, T.; Carré, B.; Salières, P.; Guichard, R.; Caillat, J.; Maquet, A.; Taïeb, R.

    2012-02-01

    When generated in molecules, high-order harmonics can be emitted through different ionization channels. The coherent and ultrafast electron dynamics occurring in the ion during the generation process is directly imprinted in the harmonic signal, i.e. in its amplitude and spectral phase. In aligned N2 molecules, we find evidence for a fast variation of this phase as a function of the harmonic order when varying the driving laser intensity. Basing our analysis on a three-step model, we find that this phase variation is a signature of transitions from a single- to a multi-channel regime. In particular, we show that significant nuclear dynamics may occur in the ionization channels on the attosecond timescale, affecting both the amplitude and the phase of the harmonic signal.

  12. Infinite capacity multi-server queue with second optional service channel

    NASA Astrophysics Data System (ADS)

    Ke, Jau-Chuan; Wu, Chia-Huang; Pearn, Wen Lea

    2013-02-01

    This paper deals with an infinite-capacity multi-server queueing system with a second optional service (SOS) channel. The inter-arrival times of arriving customers, the service times of the first essential service (FES) and the SOS channel are all exponentially distributed. A customer may leave the system after the FES channel with probability (1-θ), or at the completion of the FES may immediately require a SOS with probability θ (0 <= θ <= 1). The formulae for computing the rate matrix and stationary probabilities are derived by means of a matrix analytical approach. A cost model is developed to determine the optimal values of the number of servers and the two service rates, simultaneously, at the minimal total expected cost per unit time. Quasi-Newton method are employed to deal with the optimization problem. Under optimal operating conditions, numerical results are provided in which several system performance measures are calculated based on assumed numerical values of the system parameters.

  13. Device for modular input high-speed multi-channel digitizing of electrical data

    DOEpatents

    VanDeusen, Alan L.; Crist, Charles E.

    1995-09-26

    A multi-channel high-speed digitizer module converts a plurality of analog signals to digital signals (digitizing) and stores the signals in a memory device. The analog input channels are digitized simultaneously at high speed with a relatively large number of on-board memory data points per channel. The module provides an automated calibration based upon a single voltage reference source. Low signal noise at such a high density and sample rate is accomplished by ensuring the A/D converters are clocked at the same point in the noise cycle each time so that synchronous noise sampling occurs. This sampling process, in conjunction with an automated calibration, yields signal noise levels well below the noise level present on the analog reference voltages.

  14. A 240-channel thick film multi-chip module for readout of silicon drift detectors

    NASA Astrophysics Data System (ADS)

    Lynn, D.; Bellwied, R.; Beuttenmueller, R.; Caines, H.; Chen, W.; DiMassimo, D.; Dyke, H.; Elliott, D.; Grau, M.; Hoffmann, G. W.; Humanic, T.; Jensen, P.; Kleinfelder, S. A.; Kotov, I.; Kraner, H. W.; Kuczewski, P.; Leonhardt, B.; Li, Z.; Liaw, C. J.; LoCurto, G.; Middelkamp, P.; Minor, R.; Mazeh, N.; Nehmeh, S.; O'Conner, P.; Ott, G.; Pandey, S. U.; Pruneau, C.; Pinelli, D.; Radeka, V.; Rescia, S.; Rykov, V.; Schambach, J.; Sedlmeir, J.; Sheen, J.; Soja, B.; Stephani, D.; Sugarbaker, E.; Takahashi, J.; Wilson, K.; STAR-SVT Collaboration

    2000-01-01

    We have developed a thick film multi-chip module for readout of silicon drift (or low capacitance ˜200 fF) detectors. Main elements of the module include a custom 16-channel NPN-BJT preamplifier-shaper (PASA) and a custom 16-channel CMOS Switched Capacitor Array (SCA). The primary design criteria of the module were the minimizations of the power (12 mW/channel), noise (ENC=490 e - rms), size (20.5 mm×63 mm), and radiation length (1.4%). We will discuss various aspects of the PASA design, with emphasis on the preamplifier feedback network. The SCA is a modification of an integrated circuit that has been previously described [1]; its design features specific to its application in the SVT (Silicon Vertex Tracker in the STAR experiment at RHIC) will be discussed. The 240-channel multi-chip module is a circuit with five metal layers fabricated in thick film technology on a beryllia substrate and contains 35 custom and commercial integrated circuits. It has been recently integrated with silicon drift detectors in both a prototype system assembly for the SVT and a silicon drift array for the E896 experiment at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. We will discuss features of the module's design and fabrication, report the test results, and emphasize its performance both on the bench and under experimental conditions.

  15. Multi-channel NIRS of the primary motor cortex to discriminate hand from foot activity

    NASA Astrophysics Data System (ADS)

    Koenraadt, K. L. M.; Duysens, J.; Smeenk, M.; Keijsers, N. L. W.

    2012-08-01

    The poor spatial resolution of near-infrared spectroscopy (NIRS) makes it difficult to distinguish two closely located cortical areas from each other. Here, a combination of multi-channel NIRS and a centre of gravity (CoG) approach (widely accepted in the field of transcranial magnetic stimulation; TMS) was used to discriminate between closely located cortical areas activated during hand and foot movements. Similarly, the possibility of separating the more anteriorly represented discrete movements from rhythmic movements was studied. Thirteen healthy right-handed subjects performed rhythmic or discrete (‘task’) hand or foot (‘extremity’) tapping. Hemodynamic responses were measured using an 8-channel NIRS setup. For oxyhemoglobin (OHb) and deoxyhemoglobin (HHb), a CoG was determined for each condition using the mean hemodynamic responses and the coordinates of the channels. Significant hemodynamic responses were found for hand and foot movements. Based on the HHb responses, the NIRS-CoG of hand movements was located 0.6 cm more laterally compared to the NIRS-CoG of foot movements. For OHb responses no difference in NIRS-CoG was found for ‘extremity’ nor for ‘task’. This is the first NIRS study showing hemodynamic responses for isolated foot movements. Furthermore, HHb responses have the potential to be used in multi-channel NIRS experiments requiring differential activation of motor cortex areas linked to either hand or foot movements.

  16. Electrical properties of flexible multi-channel Si nanowire field-effect transistors depending on the number of Si nanowires.

    PubMed

    Kim, Do Hoon; Lee, Su Jeong; Lee, Sang Hoon; Myoung, Jae-Min

    2016-05-25

    Flexible multi-channel Si nanowire (NW) field-effect transistors (FETs) were investigated to determine the effect of the number of Si NWs. The Langmuir-Blodgett method was applied for the formation of well-aligned Si NW monolayers, and an ion-gel with a high dielectric constant was used as a gate insulator in a top-gate TFT structure to secure flexibility. Like typical nanoelectronic devices, the drain current changed with the number of Si NWs. However, unlike previous reports, the mobility of the multi-channel Si NW FETs increased from 42.8 to 124.6 cm(2) V(-1) s(-1) as the number of Si NWs was increased from 1 to 58. To verify the feasibility of our approach, the electrical performance of the TFTs fabricated on a flexible polyimide (PI) substrate was analyzed in respect of the bending strain (0.08-1.51%) and bending cycle (up to 12 000 cycles). As the number of Si NWs was increased, the trade-off between electrical and mechanical properties during bending tests was confirmed, and the appropriate number of Si NWs was optimized for a flexible FET with excellent performance. PMID:27149060

  17. Multi-Ion Mechanism for Ion Permeation and Block in the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel

    PubMed Central

    Linsdell, Paul; Tabcharani, Joseph A.; Hanrahan, John W.

    1997-01-01

    The mechanism of Cl− ion permeation through single cystic fibrosis transmembrane conductance regulator (CFTR) channels was studied using the channel-blocking ion gluconate. High concentrations of intracellular gluconate ions cause a rapid, voltage-dependent block of CFTR Cl− channels by binding to a site ∼40% of the way through the transmembrane electric field. The affinity of gluconate block was influenced by both intracellular and extracellular Cl− concentration. Increasing extracellular Cl− concentration reduced intracellular gluconate affinity, suggesting that a repulsive interaction occurs between Cl− and gluconate ions within the channel pore, an effect that would require the pore to be capable of holding more than one ion simultaneously. This effect of extracellular Cl− is not shared by extracellular gluconate ions, suggesting that gluconate is unable to enter the pore from the outside. Increasing the intracellular Cl− concentration also reduced the affinity of intracellular gluconate block, consistent with competition between intracellular Cl− and gluconate ions for a common binding site in the pore. Based on this evidence that CFTR is a multi-ion pore, we have analyzed Cl− permeation and gluconate block using discrete-state models with multiple occupancy. Both two- and three-site models were able to reproduce all of the experimental data with similar accuracy, including the dependence of blocker affinity on external Cl− (but not gluconate) ions and the dependence of channel conductance on Cl− concentration. The three-site model was also able to predict block by internal and external thiocyanate (SCN−) ions and anomalous mole fraction behavior seen in Cl−/SCN− mixtures. PMID:9379169

  18. Multi-Ion mechanism for ion permeation and block in the cystic fibrosis transmembrane conductance regulator chloride channel.

    PubMed

    Linsdell, P; Tabcharani, J A; Hanrahan, J W

    1997-10-01

    The mechanism of Cl ion permeation through single cystic fibrosis transmembrane conductance regulator (CFTR) channels was studied using the channel-blocking ion gluconate. High concentrations of intracellular gluconate ions cause a rapid, voltage-dependent block of CFTR Cl channels by binding to a site approximately 40% of the way through the transmembrane electric field. The affinity of gluconate block was influenced by both intracellular and extracellular Cl concentration. Increasing extracellular Cl concentration reduced intracellular gluconate affinity, suggesting that a repulsive interaction occurs between Cl and gluconate ions within the channel pore, an effect that would require the pore to be capable of holding more than one ion simultaneously. This effect of extracellular Cl is not shared by extracellular gluconate ions, suggesting that gluconate is unable to enter the pore from the outside. Increasing the intracellular Cl concentration also reduced the affinity of intracellular gluconate block, consistent with competition between intracellular Cl and gluconate ions for a common binding site in the pore. Based on this evidence that CFTR is a multi-ion pore, we have analyzed Cl permeation and gluconate block using discrete-state models with multiple occupancy. Both two- and three-site models were able to reproduce all of the experimental data with similar accuracy, including the dependence of blocker affinity on external Cl (but not gluconate) ions and the dependence of channel conductance on Cl concentration. The three-site model was also able to predict block by internal and external thiocyanate (SCN) ions and anomalous mole fraction behavior seen in Cl/SCN mixtures. PMID:9379169

  19. Time-varying bispectral analysis of visually evoked multi-channel EEG

    NASA Astrophysics Data System (ADS)

    Chandran, Vinod

    2012-12-01

    Theoretical foundations of higher order spectral analysis are revisited to examine the use of time-varying bicoherence on non-stationary signals using a classical short-time Fourier approach. A methodology is developed to apply this to evoked EEG responses where a stimulus-locked time reference is available. Short-time windowed ensembles of the response at the same offset from the reference are considered as ergodic cyclostationary processes within a non-stationary random process. Bicoherence can be estimated reliably with known levels at which it is significantly different from zero and can be tracked as a function of offset from the stimulus. When this methodology is applied to multi-channel EEG, it is possible to obtain information about phase synchronization at different regions of the brain as the neural response develops. The methodology is applied to analyze evoked EEG response to flash visual stimulii to the left and right eye separately. The EEG electrode array is segmented based on bicoherence evolution with time using the mean absolute difference as a measure of dissimilarity. Segment maps confirm the importance of the occipital region in visual processing and demonstrate a link between the frontal and occipital regions during the response. Maps are constructed using bicoherence at bifrequencies that include the alpha band frequency of 8Hz as well as 4 and 20Hz. Differences are observed between responses from the left eye and the right eye, and also between subjects. The methodology shows potential as a neurological functional imaging technique that can be further developed for diagnosis and monitoring using scalp EEG which is less invasive and less expensive than magnetic resonance imaging.

  20. Multi-Tissue Computational Modeling Analyzes Pathophysiology of Type 2 Diabetes in MKR Mice

    PubMed Central

    Kumar, Amit; Harrelson, Thomas; Lewis, Nathan E.; Gallagher, Emily J.; LeRoith, Derek; Shiloach, Joseph; Betenbaugh, Michael J.

    2014-01-01

    Computational models using metabolic reconstructions for in silico simulation of metabolic disorders such as type 2 diabetes mellitus (T2DM) can provide a better understanding of disease pathophysiology and avoid high experimentation costs. There is a limited amount of computational work, using metabolic reconstructions, performed in this field for the better understanding of T2DM. In this study, a new algorithm for generating tissue-specific metabolic models is presented, along with the resulting multi-confidence level (MCL) multi-tissue model. The effect of T2DM on liver, muscle, and fat in MKR mice was first studied by microarray analysis and subsequently the changes in gene expression of frank T2DM MKR mice versus healthy mice were applied to the multi-tissue model to test the effect. Using the first multi-tissue genome-scale model of all metabolic pathways in T2DM, we found out that branched-chain amino acids' degradation and fatty acids oxidation pathway is downregulated in T2DM MKR mice. Microarray data showed low expression of genes in MKR mice versus healthy mice in the degradation of branched-chain amino acids and fatty-acid oxidation pathways. In addition, the flux balance analysis using the MCL multi-tissue model showed that the degradation pathways of branched-chain amino acid and fatty acid oxidation were significantly downregulated in MKR mice versus healthy mice. Validation of the model was performed using data derived from the literature regarding T2DM. Microarray data was used in conjunction with the model to predict fluxes of various other metabolic pathways in the T2DM mouse model and alterations in a number of pathways were detected. The Type 2 Diabetes MCL multi-tissue model may explain the high level of branched-chain amino acids and free fatty acids in plasma of Type 2 Diabetic subjects from a metabolic fluxes perspective. PMID:25029527

  1. Corona discharge radical emission spectroscopy: a multi-channel detector with nose-type function for discrimination analysis.

    PubMed

    Tian, Yunfei; Wu, Peng; Wu, Xi; Jiang, Xiaoming; Xu, Kailai; Hou, Xiandeng

    2013-04-21

    A simple and economical multi-channel optical sensor using corona discharge radical emission spectroscopy is developed and explored as an optical nose for discrimination analysis of volatile organic compounds, wines, and even isomers. PMID:23471437

  2. Single layer, multi-channel band-gear system for rotary joint

    NASA Technical Reports Server (NTRS)

    Kong, Kin Yuen (Inventor)

    1998-01-01

    A multi-channel band-gear system for a rotary joint has a ring gear assembly with a conducting ring band in electrical contact with corresponding conducting bands of a set of intermediary planetary gears, which in turn are in electrical contact with a conducting sun band of a sun gear assembly. The ring band is formed with a plurality of conducting segments which are electrically insulated from each other and positioned angularly in a circumferential direction of the ring gear, such that separate electrical power/signal channels are formed across the rotary joint. In a preferred embodiment having continuously connected channels, the ring band has four conducting segments at 90.degree. intervals, the sun band has two conducting segments at 180.degree. intervals, and three planetary bands are in rolling electrical contact at 120.degree. intervals between the ring band segments and the sun band segments, forming two continuously connected channels in a single layer of the band-gear system. Multiple sets of ring gear, planetary gear, and sun gear assemblies may be used in a stacked configuration in a single axial layer to further increase the number of channels provided through the band-gear system.

  3. Automated Filtering of Common Mode Artifacts in Multi-Channel Physiological Recordings

    PubMed Central

    Kelly, John W.; Siewiorek, Daniel P.; Smailagic, Asim; Wang, Wei

    2014-01-01

    The removal of spatially correlated noise is an important step in processing multi-channel recordings. Here, a technique termed the adaptive common average reference (ACAR) is presented as an effective and simple method for removing this noise. The ACAR is based on a combination of the well-known common average reference (CAR) and an adaptive noise canceling (ANC) filter. In a convergent process, the CAR provides a reference to an ANC filter, which in turn provides feedback to enhance the CAR. This method was effective on both simulated and real data, outperforming the standard CAR when the amplitude or polarity of the noise changes across channels. In many cases the ACAR even outperformed independent component analysis (ICA). On 16 channels of simulated data the ACAR was able to attenuate up to approximately 290 dB of noise and could improve signal quality if the original SNR was as high as 5 dB. With an original SNR of 0 dB, the ACAR improved signal quality with only two data channels and performance improved as the number of channels increased. It also performed well under many different conditions for the structure of the noise and signals. Analysis of contaminated electrocorticographic (ECoG) recordings further showed the effectiveness of the ACAR. PMID:23708770

  4. Seafloor surface processes and subsurface paleo-channel unconformities mapped using multi-channel seismic and multi-beam sonar data from the Galicia 3D seismic experiment.

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Shillington, D. J.; Sawyer, D. S.; Jordan, B.; Morgan, J. K.; Ranero, C.; Reston, T. J.

    2015-12-01

    In this study we use geophysical methods, stratigraphic relationships, and coring/drilling leg results to assess possible controls on deep-sea channel formation in order to further constrain paleo-channel (PC) and associated unconformity timing/source processes. A series of cut and fill PC are mapped in 3D multi-channel seismic (MCS) data and compared with multi-beam (MB) sonar bathymetry/backscatter data collected during the Galicia 3D survey with the R/V Marcus G. Langseth (2013). The MCS data were collected using four 6 km streamers spaced at 200 m resulting in 25 m x 25 m common mid-point bins within the ~67 km x 20 km 3D volume. The MB data were collected at an average depth of ~4900 m with a constrained swath width of 4.5 km resulting in 11.25x overlap while enabling 25-m bathymetry and 10-m backscatter grids. The PC lie below the mouth of a submarine canyon at the edge of the Galicia abyssal plain and cut pre/syn-rift sediments; they are bound by a rift block to the north and paleo-levees to the south (maximum height of ~180m). From drilling results, the most recent PC is late Miocene in age. In this study, four PC are traced into the basin as unconformities. Several of the PC/unconformities are tentatively correlated with previously interpreted Pyrenean orogeny/compressional Miocene/Oligocene tectonic events. However, one PC/unconformity within this interval has not been previously interpreted. In order test the hypothesis that the unconformities are the result of a significant change in base level indicated by a low shale/sand (SS) ratio, we use seismic surface attributes to calculate the SS ratio and trace the horizontal extent of the unconformities. Additionally, the MB/MCS seafloor morphology reveals sedimentary waves outboard of the canyon mouth. We use backscatter data to compare the extent of recent processes (e.g., Pleistocene glaciation/de-glaciation) with the unconformities by mapping the surface/shallow subsurface SS ratio (volume scattering).

  5. A wireless multi-channel bioimpedance measurement system for personalized healthcare and lifestyle.

    PubMed

    Ramos, Javier; Ausín, José Luis; Lorido, Antonio Manuel; Redondo, Francisco; Duque-Carrillo, Juan Francisco

    2013-01-01

    Miniaturized, noninvasive, wearable sensors constitute a fundamental prerequisite for pervasive, predictive, and preventive healthcare systems. In this sense, this paper presents the design, realization, and evaluation of a wireless multi-channel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz. The resulting on-chip spectrometer provides high measuring EBI capabilities and together with a low-cost, commercially available radio frequency transceiver device. It provides reliable wireless communication, constitutes the basic node to build EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multi-channel EBI spectrometer, where the number of channels is completely scalable and independently configurable to satisfy specific measurement requirements of each individual. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery and make it suitable for long-term preventive healthcare monitoring. PMID:23739358

  6. Hand Motion Classification Using a Multi-Channel Surface Electromyography Sensor

    PubMed Central

    Tang, Xueyan; Liu, Yunhui; Lv, Congyi; Sun, Dong

    2012-01-01

    The human hand has multiple degrees of freedom (DOF) for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG) sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high. PMID:22438703

  7. Design and implementation of the parallel processing system of multi-channel polarization images

    NASA Astrophysics Data System (ADS)

    Li, Zhi-yong; Huang, Qin-chao

    2013-08-01

    Compared with traditional optical intensity image processing, polarization images processing has two main problems. One is that the amount of data is larger. The other is that processing tasks is more complex. To resolve these problems, the parallel processing system of multi-channel polarization images is designed by the multi-DSP technique. It contains a communication control unit (CCU) and a data processing array (DPA). CCU controls communications inside and outside the system. Its logics are designed by a FPGA chip. DPA is made up of four Digital Signal Processor (DSP) chips, which are interlinked by the loose coupling method. DPA implements processing tasks including images registration and images synthesis by parallel processing methods. The polarization images parallel processing model is designed on multi levels including the system task, the algorithm and the operation. Its program is designed by the assemble language. While the polarization image resolution is 782x582 pixels, the pixel data length is 12 bits in the experiment. After it received 3 channels of polarization image simultaneously, this system implements parallel task to acquire the target polarization characteristics. Experimental results show that this system has good real-time and reliability. The processing time of images registration is 293.343ms while the registration accuracy achieves 0.5 pixel. The processing time of images synthesis is 3.199ms.

  8. Multi-DSP and FPGA based Multi-channel Direct IF/RF Digital receiver for atmospheric radar

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kamaraj, Pandian; Durga rao, Meka; Thriveni, A.

    2016-07-01

    Modern phased array radars depend highly on digital signal processing (DSP) to extract the echo signal information and to accomplish reliability along with programmability and flexibility. The advent of ASIC technology has made various digital signal processing steps to be realized in one DSP chip, which can be programmed as per the application and can handle high data rates, to be used in the radar receiver to process the received signal. Further, recent days field programmable gate array (FPGA) chips, which can be re-programmed, also present an opportunity to utilize them to process the radar signal. A multi-channel direct IF/RF digital receiver (MCDRx) is developed at NARL, taking the advantage of high speed ADCs and high performance DSP chips/FPGAs, to be used for atmospheric radars working in HF/VHF bands. Multiple channels facilitate the radar t be operated in multi-receiver modes and also to obtain the wind vector with improved time resolution, without switching the antenna beam. MCDRx has six channels, implemented on a custom built digital board, which is realized using six numbers of ADCs for simultaneous processing of the six input signals, Xilinx vertex5 FPGA and Spartan6 FPGA, and two ADSPTS201 DSP chips, each of which performs one phase of processing. MCDRx unit interfaces with the data storage/display computer via two gigabit ethernet (GbE) links. One of the six channels is used for Doppler beam swinging (DBS) mode and the other five channels are used for multi-receiver mode operations, dedicatedly. Each channel has (i) ADC block, to digitize RF/IF signal, (ii) DDC block for digital down conversion of the digitized signal, (iii) decoding block to decode the phase coded signal, and (iv) coherent integration block for integrating the data preserving phase intact. ADC block consists of Analog devices make AD9467 16-bit ADCs, to digitize the input signal at 80 MSPS. The output of ADC is centered around (80 MHz - input frequency). The digitized data is fed

  9. Multi-point measurements of ULF wave phases using a multi-channel energetic ion detector

    NASA Technical Reports Server (NTRS)

    Lin, N.; Kivelson, M. G.; Mcpherron, R. L.; Williams, D. J.; Fritz, T. A.

    1988-01-01

    The oscillation of differential fluxes of energetic ions modulated by a ULF wave often shows a phase shift between measurements in back-to-back detectors with look directions perpendicular to the ambient magnetic field. In a plasma of a single ion species, the phase difference is caused by displacement of the effective measurement positions by one ion gyroradius to each side of the detector. As the wave phase is periodic, the observed phase shift can correspond to a family of possible wavelengths. Simultaneous measurements of the flux modulations in different energy channels, which are equivalent to measurements of the wave phase at different positions, may make it possible to single out a unique wavelength consistent with all the measurements. Using the medium-energy-particle experiments ISEE-1 and 2, each of which may serve as a back-to-back detector, the above method was applied to a compressional Pc 5 wave observed near the equatorial plane at L between about 7 and 11. The transverse propagation properties of the wave were determined unambiguously.

  10. Subjective evaluation of auralizations created from multi-channel anechoic recordings of a talker in motion

    NASA Astrophysics Data System (ADS)

    Vigeant, Michelle C.; Wang, Lily M.

    2005-04-01

    A high degree of speech intelligibility is very important in educational environments. When designing such spaces, like classrooms, auralizations can be used to subjectively assess the degree of speech intelligibility and clarity. Auralizations are most commonly made by convolving the impulse response (IR) of an omni-directional source with a single channel anechoic speech recording. This paper explores the idea of using multi-channel recordings to create the auralizations, using a female talker in motion. An omni-directional source is split into quadrants and the IR is calculated for each section. These IR's are convolved with the appropriate channel of the anechoic recording and then the four auralizations are mixed to create one final auralization. The auralizations were made using four-channel anechoic recordings of a person walking on a platform while talking. Subjective tests were conducted to determine the ease with which subjects could identify the direction of the movement of the source in rooms with varying amounts of absorption. This method can be used to create more realistic classroom auralizations, as teachers typically move around the room as they teach. [Work supported by the National Science Foundation.

  11. Optimization of multi-channel neutron focusing guides for extreme sample environments

    NASA Astrophysics Data System (ADS)

    Di Julio, D. D.; Lelièvre-Berna, E.; Courtois, P.; Andersen, K. H.; Bentley, P. M.

    2014-07-01

    In this work, we present and discuss simulation results for the design of multichannel neutron focusing guides for extreme sample environments. A single focusing guide consists of any number of supermirror-coated curved outer channels surrounding a central channel. Furthermore, a guide is separated into two sections in order to allow for extension into a sample environment. The performance of a guide is evaluated through a Monte-Carlo ray tracing simulation which is further coupled to an optimization algorithm in order to find the best possible guide for a given situation. A number of population-based algorithms have been investigated for this purpose. These include particle-swarm optimization, artificial bee colony, and differential evolution. The performance of each algorithm and preliminary results of the design of a multi-channel neutron focusing guide using these methods are described. We found that a three-channel focusing guide offered the best performance, with a gain factor of 2.4 compared to no focusing guide, for the design scenario investigated in this work.

  12. Centralized Routing and Scheduling Using Multi-Channel System Single Transceiver in 802.16d

    NASA Astrophysics Data System (ADS)

    Al-Hemyari, A.; Noordin, N. K.; Ng, Chee Kyun; Ismail, A.; Khatun, S.

    This paper proposes a cross-layer optimized strategy that reduces the effect of interferences from neighboring nodes within a mesh networks. This cross-layer design relies on the routing information in network layer and the scheduling table in medium access control (MAC) layer. A proposed routing algorithm in network layer is exploited to find the best route for all subscriber stations (SS). Also, a proposed centralized scheduling algorithm in MAC layer is exploited to assign a time slot for each possible node transmission. The cross-layer optimized strategy is using multi-channel single transceiver and single channel single transceiver systems for WiMAX mesh networks (WMNs). Each node in WMN has a transceiver that can be tuned to any available channel for eliminating the secondary interference. Among the considered parameters in the performance analysis are interference from the neighboring nodes, hop count to the base station (BS), number of children per node, slot reuse, load balancing, quality of services (QoS), and node identifier (ID). Results show that the proposed algorithms significantly improve the system performance in terms of length of scheduling, channel utilization ratio (CUR), system throughput, and average end to end transmission delay.

  13. Analysis of reconfigurable multi-channel wavelength add drop multiplexer for intelligent optical networks

    NASA Astrophysics Data System (ADS)

    Ponmalar, S.; Sundaravadivelu, S.

    2011-07-01

    This paper presents design of an electro-optically tunable polymer multi-channel wavelength add drop multiplexer (WADM). The proposed WADM with trapezoidal waveguide geometry and poled electro-optical polymer material in the waveguide cores enables the wavelength tuning speed of WADM as 7.5 ps at the resonance wavelength of 1550 nm and coupling length of 1.5 mm. The device can be electro-optically tuned to add/drop multiple channels. Transmission spectra of the device with varying device parameters are simulated. The proposed WADM with high speed, small size and varying tuning capability makes this device, an important element in faster provisioning and routing of light paths in intelligent optical network.

  14. Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation

    PubMed Central

    Ferré, A.; Boguslavskiy, A. E.; Dagan, M.; Blanchet, V.; Bruner, B. D.; Burgy, F.; Camper, A.; Descamps, D.; Fabre, B.; Fedorov, N.; Gaudin, J.; Geoffroy, G.; Mikosch, J.; Patchkovskii, S.; Petit, S.; Ruchon, T.; Soifer, H.; Staedter, D.; Wilkinson, I.; Stolow, A.; Dudovich, N.; Mairesse, Y.

    2015-01-01

    High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20–26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected. PMID:25608712

  15. Multi-channel quantum dragons from rectangular nanotubes with even-odd structure

    NASA Astrophysics Data System (ADS)

    Inkoom, Godfred; Novotny, Mark

    Recently, a large class of nanostructures called quantum dragons have been discovered theoretically. Quantum dragons are nanostuctures with correlated disorder but have an electron transmission probability  (E) =1 for all energies E when connected to idealized leads. Hence for a single channel, the electrical conductance for a two-probe measurement should give the quantum of conductance Go =2e2/h . The time independent Schrödinger equation for the single band tight binding model is solved exactly to obtain  (E) . We have generalized the matrix method and the mapping methods of in order to study multi-channel quantum dragons for rectangular nanotubes with even-odd structure. The studies may be relevant for experimental rectangular nanotubes, such as MgO, copper phthalocyanine or some types of graphyne.. Supported in part by NSF Grant DMR-1206233.

  16. Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation.

    PubMed

    Ferré, A; Boguslavskiy, A E; Dagan, M; Blanchet, V; Bruner, B D; Burgy, F; Camper, A; Descamps, D; Fabre, B; Fedorov, N; Gaudin, J; Geoffroy, G; Mikosch, J; Patchkovskii, S; Petit, S; Ruchon, T; Soifer, H; Staedter, D; Wilkinson, I; Stolow, A; Dudovich, N; Mairesse, Y

    2015-01-01

    High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20-26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected. PMID:25608712

  17. Low-cost high performance distributed data storage for multi-channel observations

    NASA Astrophysics Data System (ADS)

    Liu, Ying-bo; Wang, Feng; Deng, Hui; Ji, Kai-fan; Dai, Wei; Wei, Shou-lin; Liang, Bo; Zhang, Xiao-li

    2015-10-01

    The New Vacuum Solar Telescope (NVST) is a 1-m solar telescope that aims to observe the fine structures in both the photosphere and the chromosphere of the Sun. The observational data acquired simultaneously from one channel for the chromosphere and two channels for the photosphere bring great challenges to the data storage of NVST. The multi-channel instruments of NVST, including scientific cameras and multi-band spectrometers, generate at least 3 terabytes data per day and require high access performance while storing massive short-exposure images. It is worth studying and implementing a storage system for NVST which would balance the data availability, access performance and the cost of development. In this paper, we build a distributed data storage system (DDSS) for NVST and then deeply evaluate the availability of real-time data storage on a distributed computing environment. The experimental results show that two factors, i.e., the number of concurrent read/write and the file size, are critically important for improving the performance of data access on a distributed environment. Referring to these two factors, three strategies for storing FITS files are presented and implemented to ensure the access performance of the DDSS under conditions of multi-host write and read simultaneously. The real applications of the DDSS proves that the system is capable of meeting the requirements of NVST real-time high performance observational data storage. Our study on the DDSS is the first attempt for modern astronomical telescope systems to store real-time observational data on a low-cost distributed system. The research results and corresponding techniques of the DDSS provide a new option for designing real-time massive astronomical data storage system and will be a reference for future astronomical data storage.

  18. Multi-channel analysis of passive surface waves based on cross-correlations

    NASA Astrophysics Data System (ADS)

    Cheng, F.; Xia, J.; Xu, Z.; Hu, Y.

    2015-12-01

    Traditional active seismic survey can no longer be properly applied in highly populated urban areas due to restrictions in modern civilian life styles. Passive seismic methods, however, have gained much more attention from the engineering geophysics community because of their environmental friendly and deeper investigation depth. Due to extracting signal from noise has never been as comfortable as that in active seismic survey, how to make it more efficiently and accurately has been emphasized. We propose a multi-channel analysis of passive surface waves (MAPW) based on long noise sequences cross-correlations to meet the demand for increasing investigation depth by acquiring surface-wave data at a relative low-frequency range (1 Hz ≤ f ≤ 10 Hz) in urban areas. We utilize seismic interferometry to produce common virtual source gathers from one-hour-long noise records and do dispersion measurements by using the classic passive multi-channel analysis of surface waves (PMASW). We used synthetic tests to demonstrate the advantages of MAPW for various noise distributions. Results show that our method has the superiority of maximizing the analysis accuracy. Finally, we used two field data applications to demonstrate the advantages of our MAPW over the classic PMASW on isolating azimuth of the predominant noise sources and the effectivity of combined survey of active multi-channel analysis of surface waves (MASW) and MAPW. We suggest, for the field operation using MAPW, that a parallel receiver line which is close to a main road or river, if any, with one or two hours noise observation will be an effective means for an unbiased dispersion image. Keywords: passive seismic method, MAPW, MASW, cross-correlation, directional noise source, spatial-aliasing effects, inversion

  19. Coherent state transfer through a multi-channel quantum network: Natural versus controlled evolution passage

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Li, Yong

    2016-04-01

    Quantum state transfer (QST) is an important task in quantum information processing. In this study, we describe two approaches for the high-fidelity transfer of a quantum state between two opposite quantum dots attached to a multi-channel quantum network. First, we demonstrate that a high-efficiency QST can be achieved with the coherent time evolution of a quantum system without any external control. Second, we present an approach that uses an alternative mechanism for a high-fidelity QST. By adiabatically varying tunnel couplings, it is possible to implement the complete transmission of a quantum state based on this quantum mechanical mechanism.

  20. Note: An underwater multi-channel plasma array for water sterilization

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Kim, H.; Starikovskiy, A.; Cho, Y. I.; Fridman, A.

    2011-09-01

    A simple yet effective method to generate multi-channel plasma array in water is presented in this paper. Thin circular metal disks sandwiched between dielectric layers were used, allowing the production of large-volume underwater plasma array with higher stability. The system can be further scaled up by stacking multiple metal disks, making it suitable for large-scale industrial water treatment. Generation of UV and reactive species was identified by optical emission spectroscopy. Sterilization experiments were performed. Results show that the device was effective in deactivating E. coli in water over a wide range of initial concentrations ranging from 104 to 108 CFU/ml.

  1. Multi-channel optical pyrometer for sub-nanosecond temperature measurements at NDCX-I/II

    SciTech Connect

    Ni, P.A.; Bieniosek, F.M.; Waldron, W.L.

    2011-04-13

    We present a detailed technical description of a fast multi-channel pyrometer designed for warm-dense-matter (WDM) experiments with intense heavy ion beams at the neutralized-drift-compression-experiment linear accelerator (NDCX-I/II) at Lawrence Berkeley National Laboratory (LBNL). The unique features of the described instrument are its sub-nanosecond temporal resolution (100 ps rise-time) and a broad range, 1,500 K - 12,000 K of measurable brightness temperatures in the visible and near-infrared regions of the spectrum. The working scheme, calibration procedure, experimental data obtained with the pyrometer and future applications are presented.

  2. Optical-network-connected multi-channel 96-GHz-band distributed radar system

    NASA Astrophysics Data System (ADS)

    Kanno, Atsushi; Kuri, Toshiaki; Kawanishi, Tetsuya

    2015-05-01

    The millimeter-wave (MMW) radar is a promising candidate for high-precision imaging because of its short wavelength and broad range of available bandwidths. In particular in the frequency range of 92-100 GHz, which is regulated for radiolocation, an atmospheric attenuation coefficient less than 1 dB/km limits the imaging range. Therefore, a combination of MMW radar and distributed antenna system directly connected to optical fiber networks can realize both high-precision imaging and large-area surveillance. In this paper, we demonstrate a multi-channel MMW frequency-modulated continuous-wave distributed radar system connected to an analog radio-over-fiber network.

  3. Extending plasma channel of filamentation with a multi-focal-length beam.

    PubMed

    Hong, Zuofei; Zhang, Qingbin; Ali Rezvani, S; Lan, Pengfei; Lu, Peixiang

    2016-02-22

    We propose a novel scheme that lengthens the plasma channel in filamentation with a multi-focal-length beam. Instead of one focal length introduced by a conventional convex lens, the multi-focal-length beam modulated by a spatial light modulator (SLM) produces a filament in an extended range with limited but strictly manipulated laser energy. The results show that the scheme is capable of doubling the filament length compared to a single-lens scheme with a 2-mJ input pulse. The filament location and length can be simply tuned by altering the spatial amplitude and phase or employing higher energies. Furthermore, the extended filament length leads to the generation of a broadened continuum ranging from visible (VIS) to infrared (IR) domain. This versatile scheme offers an efficient tool for the development of a variety of applications involving ultrafast nonlinear optics. PMID:26907055

  4. Science opportunity analyzer - a multi-mission approach to science planning

    NASA Technical Reports Server (NTRS)

    Streiffert, B. A.; Polanskey, C. A.; O'Reilly, T.; Colwell, J.

    2003-01-01

    In the past Science Planning for space missions has been comprised of using ad-hoc software toolscollected or reconstructed from previous missions, tools used by other groups who often speak a different 'technical' language or even 'the backs of envelopes'. In addition to the tools being rough, the work done with these tools often has had to be redone or at least re-entered when it came time to determine actual observations. Science Opportunity Analyzer (SOA), a Java-based application, has been built for scientists to enable them to identify/analyze observation opportunities and then, to create corresponding observation designs.

  5. An open source workbook in Excel for viewing and analyzing demagnetization data from paleomagnetic discrete samples and u-channels

    NASA Astrophysics Data System (ADS)

    Sagnotti, L.

    2012-12-01

    Modern rock magnetometers and stepwise demagnetization procedures result in the production of large datasets, which need a versatile and fast software for their display and analysis. Various software packages for paleomagnetic analyses have been recently developed to overcome the problems linked to the limited capability and the loss of operability of early codes written in obsolete computer languages and/or platforms, not compatible with modern 64 bit processors. Here I present a new software for viewing and analyzing demagnetization data from paleomagnetic discrete samples and u-channels, which consists of a workbook for Microsoft Excel. The widespread diffusion of Excel ensures multiplatform operability and offers guarantees for long term operability, independently form the development of new processors and operating systems. In order to reduce the problems linked to the rapid evolution of the programming environments, the workbook makes use of a few macros, written in Visual Basic and necessary only to automatically save the output data. The workbook is designed for an interactive operability and all the commands and choices can be entered by sliding menus associated to single cells. All the standard demagnetization diagrams (Zijderveld orthogonal projection diagrams, stereographic projection of unit vectors, decay of the remanence intensity) are featured and both the user-driven and the automatic computation of the remanence characteristic components by principal component analysis are allowed. In addition, various other common demagnetization parameters (MDF, deltaGRM) are computed. The whole workbook is free for use and modification. The program has the following features which may be valuable for various users: - Operability in nearly all the computers and platforms; - Easy inputs of demagnetization data by "copy and paste" from ASCII files. The required data consist of only 9 columns: (1) sample code, (2) demagnetization steps, (3-5) raw measurements from

  6. Leader-following consensus of high-order multi-agent linear systems with bounded transmission channels

    NASA Astrophysics Data System (ADS)

    Ni, Wei; Xiong, Chun; Yang, Jie

    2013-09-01

    The leader-following consensus of high-order multi-agent linear systems with bounded transmission channels is considered. Agents modelled as LTI dynamics exchange information according to a network which can be described as a graph with agents as its vertices and information transmission channels as its edges. The transmission channels are bounded. The objective is leader-following in the sense that the state of all agents should converge to that of the leader vehicle. Detailed analysis of the leader-following consensus under bounded transmission channels is investigated for both fixed and switching network topologies.

  7. A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images.

    PubMed

    Zhong, Xinke; Labed, Jelila; Zhou, Guoqing; Shao, Kun; Li, Zhao-Liang

    2015-01-01

    The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800-1200 cm(-1) and a spectral sampling frequency of 0.25 cm(-1). We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product. PMID:26061199

  8. A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images

    PubMed Central

    Zhong, Xinke; Labed, Jelila; Zhou, Guoqing; Shao, Kun; Li, Zhao-Liang

    2015-01-01

    The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800–1200 cm−1 and a spectral sampling frequency of 0.25 cm−1. We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product. PMID:26061199

  9. Analyzing soil erosion using a multi-temporal UAV data set after one year of active agriculture in Navarra, Spain

    NASA Astrophysics Data System (ADS)

    Anders, Niels; Keesstra, Saskia; Masselink, Rens

    2014-05-01

    Unmanned Aerial System (UAS) are becoming popular tools in the geosciences due to improving technology and processing/analysis techniques. They can potentially fill the gap between spaceborne or manned aircraft remote sensing and terrestrial remote sensing, both in terms of spatial and temporal resolution. In this study we analyze a multi-temporal data set that was acquired with a fixed-wing UAS in an agricultural catchment (2 sq. km) in Navarra, Spain. The goal of this study is to register soil erosion activity after one year of agricultural activity. The aircraft was equipped with a Panasonic GX1 16MP pocket camera with a 20 mm lens to capture normal JPEG RGB images. The data set consisted of two sets of imagery acquired in the end of February in 2013 and 2014 after harvesting. The raw images were processed using Agisoft Photoscan Pro which includes the structure-from-motion (SfM) and multi-view stereopsis (MVS) algorithms producing digital surface models and orthophotos of both data sets. A discussion is presented that is focused on the suitability of multi-temporal UAS data and SfM/MVS processing for quantifying soil loss, mapping the distribution of eroded materials and analyzing re-occurrences of rill patterns after plowing.

  10. Robust detection of multiple sclerosis lesions from intensity-normalized multi-channel MRI

    NASA Astrophysics Data System (ADS)

    Karpate, Yogesh; Commowick, Olivier; Barillot, Christian

    2015-03-01

    Multiple sclerosis (MS) is a disease with heterogeneous evolution among the patients. Quantitative analysis of longitudinal Magnetic Resonance Images (MRI) provides a spatial analysis of the brain tissues which may lead to the discovery of biomarkers of disease evolution. Better understanding of the disease will lead to a better discovery of pathogenic mechanisms, allowing for patient-adapted therapeutic strategies. To characterize MS lesions, we propose a novel paradigm to detect white matter lesions based on a statistical framework. It aims at studying the benefits of using multi-channel MRI to detect statistically significant differences between each individual MS patient and a database of control subjects. This framework consists in two components. First, intensity standardization is conducted to minimize the inter-subject intensity difference arising from variability of the acquisition process and different scanners. The intensity normalization maps parameters obtained using a robust Gaussian Mixture Model (GMM) estimation not affected by the presence of MS lesions. The second part studies the comparison of multi-channel MRI of MS patients with respect to an atlas built from the control subjects, thereby allowing us to look for differences in normal appearing white matter, in and around the lesions of each patient. Experimental results demonstrate that our technique accurately detects significant differences in lesions consequently improving the results of MS lesion detection.

  11. Multi-channeled single chain variable fragment (scFv) based microfluidic device for explosives detection.

    PubMed

    Charles, Paul T; Davis, Jasmine; Adams, André A; Anderson, George P; Liu, Jinny L; Deschamps, Jeffrey R; Kusterbeck, Anne W

    2015-11-01

    The development of explosives detection technologies has increased significantly over the years as environmental and national security agencies implement tighter pollution control measures and methods for improving homeland security. 2, 4, 6-Trinitrotoluene (TNT), known primarily as a component in munitions, has been targeted for both its toxicity and carcinogenic properties that if present at high concentrations can be a detriment to both humans, marine and plant ecosystems. Enabling end users with environmental detection and monitoring systems capable of providing real-time, qualitative and quantitative chemical analysis of these toxic compounds would be extremely beneficial. Reported herein is the development of a multi-channeled microfluidic device immobilized with single chain fragment variable (scFv) recombinant proteins specific for the explosive, TNT. Fluorescence displacement immunoassays performed under constant flow demonstrated trace level sensitivity and specificity for TNT. The utility of three multi-channeled devices immobilized with either (1) scFv recombinant protein, (2) biotinylated-scFv (bt-scFv) and (3) monoclonal anti-TNT (whole IgG molecule) were investigated and compared. Fluorescence dose response curves, crossreactivity measurements and limits of detection (LOD) for TNT were determined. Fluorescence displacement immunoassays for TNT in natural seawater demonstrated detection limits at sub-parts-per-billion levels (0.5 ppb) utilizing the microfluidic device with immobilized bt-scFv. PMID:26452845

  12. The application of elastomeric connector for multi-channel electrophysiological recordings.

    PubMed

    Szabó, Imre; Máthé, Kálmán; Tóth, Attila; Hernádi, István; Czurkó, András

    2002-02-15

    Interest in recording multi-channel electrophysiological data from behaving animals is rapidly growing, and many laboratories tend to record a large number of EEG and/or multi-unit channels, despite the limitation of the size of the headpiece that a small behaving animal can carry. A common drawback of these experiments, therefore, is the relatively large size of even the smallest, commercially available, high-density micro-connectors for the headset. To overcome this problem, we suggest the application of elastomeric or silicone inter-rubber connectors, that are widely used in electronics. The elastomeric or "zebra" connector consists of alternating thin strips of layered electrically conductive and non-conductive materials. The conductive strips provide electrical connections between uninsulated contact surfaces of printed circuit boards such as the connector plate of the micro-drive, that holds the brain electrode wires, and the preamplifier board of the recording system. In the present paper, we provide technical details of the design of this type of connector-sets and discuss common issues arising from their use. By comparing the applicability of two designs, we aim to demonstrate the simplicity, reliability and durability of the elastomeric inter-rubber connectors in electrophysiological experiments on freely moving laboratory animals. PMID:11850041

  13. Multi-Channel neurodegenerative pattern analysis and its application in Alzheimer's disease characterization

    PubMed Central

    Liu, Sidong; Cai, Weidong; Wen, Lingfeng; Feng, David Dagan; Pujol, Sonia; Kikinis, Ron; Fulham, Michael J.; Eberl, Stefan; ADNI

    2014-01-01

    Neuroimaging has played an important role in non-invasive diagnosis and differentiation of neurodegenerative disorders, such as Alzheimer's disease and Mild Cognitive Impairment. Various features have been extracted from the neuroimaging data to characterize the disorders, and these features can be roughly divided into global and local features. Recent studies show a tendency of using local features in disease characterization, since they are capable of identifying the subtle disease-specific patterns associated with the effects of the disease on human brain. However, problems arise if the neuroimaging database involved multiple disorders or progressive disorders, as disorders of different types or at different progressive stages might exhibit different degenerative patterns. It is difficult for the researchers to reach consensus on what brain regions could effectively distinguish multiple disorders or multiple progression stages. In this study we proposed a Multi-Channel pattern analysis approach to identify the most discriminative local brain metabolism features for neurodegenerative disorder characterization. We compared our method to global methods and other pattern analysis methods based on clinical expertise or statistics tests. The preliminary results suggested that the proposed Multi-Channel pattern analysis method outperformed other approaches in Alzheimer's disease characterization, and meanwhile provided important insights into the underlying pathology of Alzheimer's disease and Mild Cognitive Impairment. PMID:24933011

  14. BioSigPlot: an opensource tool for the visualization of multi-channel biomedical signals with Matlab.

    PubMed

    Boudet, Samuel; Peyrodie, Laurent; Gallois, Philippe; de l'Aulnoit, Denis Houzé; Cao, Hua; Forzy, Gérard

    2013-01-01

    This paper presents a Matlab-based software (MathWorks inc.) called BioSigPlot for the visualization of multi-channel biomedical signals, particularly for the EEG. This tool is designed for researchers on both engineering and medicine who have to collaborate to visualize and analyze signals. It aims to provide a highly customizable interface for signal processing experimentation in order to plot several kinds of signals while integrating the common tools for physician. The main advantages compared to other existing programs are the multi-dataset displaying, the synchronization with video and the online processing. On top of that, this program uses object oriented programming, so that the interface can be controlled by both graphic controls and command lines. It can be used as EEGlab plug-in but, since it is not limited to EEG, it would be distributed separately. BioSigPlot is distributed free of charge (http://biosigplot.sourceforge.net), under the terms of GNU Public License for non-commercial use and open source development. PMID:24110098

  15. Satellite rainfall monitoring over Africa for food security, using multi-channel MSG data

    NASA Astrophysics Data System (ADS)

    Chadwick, R.; Grimes, D.; Saunders, R.; Blackmore, T.; Francis, P.

    2009-04-01

    Near real-time rainfall estimates are crucial in sub-Saharan Africa for a variety of humanitarian and agricultural purposes. However, for economic and infrastructural reasons, regularly reporting rain-gauges are sparse and precipitation radar networks extremely rare. Satellite rainfall estimates, particularly from geostationary satellites such as Meteosat Second Generation (MSG), present one method of filling this information gap, as they produce data at high temporal and spatial resolution. An algorithm has been developed to produce rainfall estimates for Africa from multi-channel MSG data. The algorithm is calibrated using precipitation radar data collected in Niamey, Niger as part of the African Monsoon Multidisciplinary Analyses (AMMA) project in 2006, and is based on an algorithm used operationally over Europe by the UK Met Office. Contingency tables are used to establish a statistical relationship between multi-channel MSG data and probability of rainfall at several different rain-rate magnitudes as sensed by the radar. Rain-rate estimates can then be produced at a variety of spatial and temporal scales, with MSG scan length (15 minutes) and pixel size (3-4km) as the lower limit. Results will be presented of a validation of this algorithm over the Sahel region of Africa. Rainfall estimates from this algorithm, processed for 2004, will be validated against gridded rain-gauge data at a 0.5 degree and 10 day timescale suitable for drought monitoring purposes. A comparison will also be made against rainfall estimates from the TAMSAT algorithm, which uses single channel IR data from MSG, and has been shown to perform well in the Sahel region.

  16. Retrieving Land Surface Temperature from Hyperspectral Thermal Infrared Data Using a Multi-Channel Method

    PubMed Central

    Zhong, Xinke; Huo, Xing; Ren, Chao; Labed, Jelila; Li, Zhao-Liang

    2016-01-01

    Land Surface Temperature (LST) is a key parameter in climate systems. The methods for retrieving LST from hyperspectral thermal infrared data either require accurate atmospheric profile data or require thousands of continuous channels. We aim to retrieve LST for natural land surfaces from hyperspectral thermal infrared data using an adapted multi-channel method taking Land Surface Emissivity (LSE) properly into consideration. In the adapted method, LST can be retrieved by a linear function of 36 brightness temperatures at Top of Atmosphere (TOA) using channels where LSE has high values. We evaluated the adapted method using simulation data at nadir and satellite data near nadir. The Root Mean Square Error (RMSE) of the LST retrieved from the simulation data is 0.90 K. Compared with an LST product from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat, the error in the LST retrieved from the Infared Atmospheric Sounding Interferometer (IASI) is approximately 1.6 K. The adapted method can be used for the near-real-time production of an LST product and to provide the physical method to simultaneously retrieve atmospheric profiles, LST, and LSE with a first-guess LST value. The limitations of the adapted method are that it requires the minimum LSE in the spectral interval of 800–950 cm−1 larger than 0.95 and it has not been extended for off-nadir measurements. PMID:27187408

  17. Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary

    PubMed Central

    Shaha, Dinesh Chandra; Cho, Yang-Ki

    2016-01-01

    Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. The formation of a salt plug in response to changes in river discharge was investigated using a conductivity-temperature-depth (CTD) recorder during spring and neap tides in the dry and wet seasons in 2014. An exportation of saline water from the Shibsa River Estuary (SRE) to the PRE through the Chunkhuri Channel occurred during the dry season, and a salt plug was created and persisted from December to June near Chalna in the PRE. A discharge-induced, relatively high water level in the PRE during the wet season exerted hydrostatic pressure towards the SRE from the PRE and thereby prevented the intrusion of salt water from the SRE to the PRE. PMID:27255892

  18. Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary.

    PubMed

    Shaha, Dinesh Chandra; Cho, Yang-Ki

    2016-01-01

    Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. The formation of a salt plug in response to changes in river discharge was investigated using a conductivity-temperature-depth (CTD) recorder during spring and neap tides in the dry and wet seasons in 2014. An exportation of saline water from the Shibsa River Estuary (SRE) to the PRE through the Chunkhuri Channel occurred during the dry season, and a salt plug was created and persisted from December to June near Chalna in the PRE. A discharge-induced, relatively high water level in the PRE during the wet season exerted hydrostatic pressure towards the SRE from the PRE and thereby prevented the intrusion of salt water from the SRE to the PRE. PMID:27255892

  19. Retrieving Land Surface Temperature from Hyperspectral Thermal Infrared Data Using a Multi-Channel Method.

    PubMed

    Zhong, Xinke; Huo, Xing; Ren, Chao; Labed, Jelila; Li, Zhao-Liang

    2016-01-01

    Land Surface Temperature (LST) is a key parameter in climate systems. The methods for retrieving LST from hyperspectral thermal infrared data either require accurate atmospheric profile data or require thousands of continuous channels. We aim to retrieve LST for natural land surfaces from hyperspectral thermal infrared data using an adapted multi-channel method taking Land Surface Emissivity (LSE) properly into consideration. In the adapted method, LST can be retrieved by a linear function of 36 brightness temperatures at Top of Atmosphere (TOA) using channels where LSE has high values. We evaluated the adapted method using simulation data at nadir and satellite data near nadir. The Root Mean Square Error (RMSE) of the LST retrieved from the simulation data is 0.90 K. Compared with an LST product from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat, the error in the LST retrieved from the Infared Atmospheric Sounding Interferometer (IASI) is approximately 1.6 K. The adapted method can be used for the near-real-time production of an LST product and to provide the physical method to simultaneously retrieve atmospheric profiles, LST, and LSE with a first-guess LST value. The limitations of the adapted method are that it requires the minimum LSE in the spectral interval of 800-950 cm(-1) larger than 0.95 and it has not been extended for off-nadir measurements. PMID:27187408

  20. Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary

    NASA Astrophysics Data System (ADS)

    Shaha, Dinesh Chandra; Cho, Yang-Ki

    2016-06-01

    Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. The formation of a salt plug in response to changes in river discharge was investigated using a conductivity-temperature-depth (CTD) recorder during spring and neap tides in the dry and wet seasons in 2014. An exportation of saline water from the Shibsa River Estuary (SRE) to the PRE through the Chunkhuri Channel occurred during the dry season, and a salt plug was created and persisted from December to June near Chalna in the PRE. A discharge-induced, relatively high water level in the PRE during the wet season exerted hydrostatic pressure towards the SRE from the PRE and thereby prevented the intrusion of salt water from the SRE to the PRE.

  1. Multi-channel linear descriptors for event-related EEG collected in brain computer interface

    NASA Astrophysics Data System (ADS)

    Pei, Xiao-mei; Zheng, Chong-xun; Xu, Jin; Bin, Guang-yu; Wang, Hong-wu

    2006-03-01

    By three multi-channel linear descriptors, i.e. spatial complexity (Ω), field power (Σ) and frequency of field changes (Φ), event-related EEG data within 8-30 Hz were investigated during imagination of left or right hand movement. Studies on the event-related EEG data indicate that a two-channel version of Ω, Σ and Φ could reflect the antagonistic ERD/ERS patterns over contralateral and ipsilateral areas and also characterize different phases of the changing brain states in the event-related paradigm. Based on the selective two-channel linear descriptors, the left and right hand motor imagery tasks are classified to obtain satisfactory results, which testify the validity of the three linear descriptors Ω, Σ and Φ for characterizing event-related EEG. The preliminary results show that Ω, Σ together with Φ have good separability for left and right hand motor imagery tasks, which could be considered for classification of two classes of EEG patterns in the application of brain computer interfaces.

  2. MULTI-DIMENSIONAL RADIATIVE TRANSFER TO ANALYZE HANLE EFFECT IN Ca II K LINE AT 3933 A

    SciTech Connect

    Anusha, L. S.; Nagendra, K. N. E-mail: knn@iiap.res.in

    2013-04-20

    Radiative transfer (RT) studies of the linearly polarized spectrum of the Sun (the second solar spectrum) have generally focused on line formation, with an aim to understand the vertical structure of the solar atmosphere using one-dimensional (1D) model atmospheres. Modeling spatial structuring in the observations of the linearly polarized line profiles requires the solution of multi-dimensional (multi-D) polarized RT equation and a model solar atmosphere obtained by magnetohydrodynamical (MHD) simulations of the solar atmosphere. Our aim in this paper is to analyze the chromospheric resonance line Ca II K at 3933 A using multi-D polarized RT with the Hanle effect and partial frequency redistribution (PRD) in line scattering. We use an atmosphere that is constructed by a two-dimensional snapshot of the three-dimensional MHD simulations of the solar photosphere, combined with columns of a 1D atmosphere in the chromosphere. This paper represents the first application of polarized multi-D RT to explore the chromospheric lines using multi-D MHD atmospheres, with PRD as the line scattering mechanism. We find that the horizontal inhomogeneities caused by MHD in the lower layers of the atmosphere are responsible for strong spatial inhomogeneities in the wings of the linear polarization profiles, while the use of horizontally homogeneous chromosphere (FALC) produces spatially homogeneous linear polarization in the line core. The introduction of different magnetic field configurations modifies the line core polarization through the Hanle effect and can cause spatial inhomogeneities in the line core. A comparison of our theoretical profiles with the observations of this line shows that the MHD structuring in the photosphere is sufficient to reproduce the line wings and in the line core, but only line center polarization can be reproduced using the Hanle effect. For a simultaneous modeling of the line wings and the line core (including the line center), MHD atmospheres with

  3. Multi-purpose fast neutron spectrum analyzer with real-time signal processing

    NASA Astrophysics Data System (ADS)

    Sulyaev, Yu. S.; Puryga, E. A.; Khilchenko, A. D.; Kvashnin, A. N.; Polosatkin, S. V.; Rovenskikh, A. F.; Burdakov, A. V.; Grishnyaev, E. V.

    2013-08-01

    Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2-5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (˜100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of 60Co and 252Cf radiation sources, and deuterium neutron generator.

  4. Uncovering patterns of forearm muscle activity using multi-channel mechanomyography.

    PubMed

    Alves, Natasha; Chau, Tom

    2010-10-01

    A coordinated activation of distal forearm muscles allows the hand and fingers to be shaped during movement and grasp. However, little is known about how the muscle activation patterns are reflected in multi-channel mechanomyogram (MMG) signals. The purpose of this study is to determine if multi-site MMG signals exhibit distinctive patterns of forearm muscle activity. MMG signals were recorded from forearm muscle sites of nine able-bodied participants during hand movement. By using 14 features selected by a genetic algorithm and classified by a linear discriminant analysis classifier (LDA), we show that MMG patterns are specific and consistent enough to identify 7+/-1 hand movements with an accuracy of 90+/-4%. MMG-based movement recognition required a minimum of three recording sites. Further, by classifying five classes of contraction patterns with 98+/-3% accuracy from MMG signals recorded from the residual limb of an amputee participant, we demonstrate that MMG shows pattern-specificity even in the absence of typical musculature. Multi-site monitoring of the RMS of MMG signals is suggested as a method of estimating the relative contributions of muscles to motor tasks. The patterns in MMG facilitate our understanding of the mechanical activity of muscles during movement. PMID:19854064

  5. Simple charge division readouts for imaging scintillator arrays using a multi-channel PMT

    SciTech Connect

    Siegel, S.; Silverman, R.W.; Shao, Y.; Cherry, S.R.

    1996-06-01

    Three simple charge division circuits were assembled and tested as 2-D position encoding readouts for multi-channel photomultiplier tubes (MC-PMT). They were evaluated with an 8 x 8 array of individual scintillators (2 x 2 x 10 mm BGO) coupled to a 64 channel MC-PMT (Philips XP1722) via 25 cm long, 2 mm diameter, double clad, optical fibers (Kuraray). This type of gamma-ray imaging detector has many potential applications in medical and industrial imaging. Though independent channel readout would allow for the discrimination of scatter within the array, and higher count rates, it would also require an excessive amount of supporting electronics. This is especially true for systems comprised of many MC-PMTs. In this study, the number of channels being read out was reduced from 64 to 4 using three different simple resistor networks. These circuits take advantage of the discretized nature of the scintillator array, the low interchannel crosstalk of the MC-PMT and low input impedance current-sensitive preamplifiers. For each circuit, the scintillator identification accuracy was compared. The identification accuracy as a function of deposited energy was also determined by exposure to various gamma-ray emitters. It was found that the preamplifier circuit noise contributed the most to the degradation of the detector`s spatial response so several low noise op amps were evaluated. It was also determined that keeping the preamplifier input impedance small was necessary for accurate positioning. The coincidence timing resolution of the detector (15 ns) is only slightly degraded by the readout circuit.

  6. The SRI24 Multi-Channel Atlas of Normal Adult Human Brain Structure

    PubMed Central

    Rohlfing, Torsten; Zahr, Natalie M.; Sullivan, Edith V.; Pfefferbaum, Adolf

    2010-01-01

    This paper describes the SRI24 atlas, a new standard reference system of normal human brain anatomy, that was created using template-free population registration of high-resolution magnetic resonance images acquired at 3T in a group of 24 normal control subjects. The atlas comprises anatomical channels (T1, T2, and proton density weighted), diffusion-related channels (fractional anisotropy, mean diffusivity, longitudinal diffusivity, mean diffusion-weighted image), tissue channels (CSF probability, gray matter probability, white matter probability, tissue labels), and two cortical parcellation maps. The SRI24 atlas enables multi-channel atlas-to-subject image registration. It is uniquely versatile in that it is equally suited for the two fundamentally different atlas applications: label propagation and spatial normalization. Label propagation, herein demonstrated using DTI fiber tracking, is enabled by the increased sharpness of the SRI24 atlas compared with other available atlases. Spatial normalization, herein demonstrated using data from a young-old group comparison study, is enabled by its unbiased average population shape property. For both propagation and normalization, we also report the results of quantitative comparisons with seven other published atlases: Colin27, MNI152, ICBM452 (warp5 and air12), and LPBA40 (SPM5, FLIRT, AIR). Our results suggest that the SRI24 atlas, although based on 3T MR data, allows equally accurate spatial normalization of data acquired at 1.5T as the comparison atlases, all of which are based on 1.5T data. Furthermore, the SRI24 atlas is as suitable for label propagation as the comparison atlases and detailed enough to allow delineation of anatomical structures for this purpose directly in the atlas. PMID:20017133

  7. Barbed channels enhance unidirectional connectivity between neuronal networks cultured on multi electrode arrays

    PubMed Central

    le Feber, Joost; Postma, Wybren; de Weerd, Eddy; Weusthof, Marcel; Rutten, Wim L. C.

    2015-01-01

    Cultured neurons on multi electrode arrays (MEAs) have been widely used to study various aspects of neuronal (network) functioning. A possible drawback of this approach is the lack of structure in these networks. At the single cell level, several solutions have been proposed to enable directed connectivity, and promising results were obtained. At the level of connected sub-populations, a few attempts have been made with promising results. First assessment of the designs' functionality, however, suggested room for further improvement. We designed a two chamber MEA aiming to create a unidirectional connection between the networks in both chambers (“emitting” and “receiving”). To achieve this unidirectionality, all interconnecting channels contained barbs that hindered axon growth in the opposite direction (from receiving to emitting chamber). Visual inspection showed that axons predominantly grew through the channels in the promoted direction. This observation was confirmed by spontaneous activity recordings. Cross-correlation between the signals from two electrodes inside the channels suggested signal propagation at ≈2 m/s from emitting to receiving chamber. Cross-correlation between the firing patterns in both chambers indicated that most correlated activity was initiated in the emitting chamber, which was also reflected by a significantly lower fraction of partial bursts (i.e., a one-chamber-only burst) in the emitting chamber. Finally, electrical stimulation in the emitting chamber induced a fast response in that chamber, and a slower response in the receiving chamber. Stimulation in the receiving chamber evoked a fast response in that chamber, but no response in the emitting chamber. These results confirm the predominantly unidirectional nature of the connecting channels from emitting to receiving chamber. PMID:26578869

  8. Multi-Parameter Cell Affinity Chromatography: Separation and Analysis in a Single Microfluidic Channel

    PubMed Central

    Li, Peng; Gao, Yan; Pappas, Dimitri

    2012-01-01

    The ability to sort and capture more than one cell type from a complex sample will enable a wide variety of studies of cell proliferation, death, and the analysis of disease states. In this work, we integrated a pneumatic actuated control layer to an affinity separation layer to create different antibody coating regions on the same fluidic channel. The comparison of different antibody capture capabilities to the same cell line was demonstrated by flowing Ramos cells through anti-CD19 and anti-CD71 coated regions in the same channel, respectively. It was determined that cell capture density on anti-CD19 region was 2.44±0.13 times higher than on anti-CD71 coated region. This approach can be used to test different affinity molecules for selectivity and capture efficiency using a single cell line in one separation. Selective capture of Ramos and HuT 78 cells from a mixture was also demonstrated using two antibody regions in the same channel. Greater than 90% purity was obtained on both capture areas in both continuous flow and stop flow separation modes. A four-region antibody coated device was then fabricated to study the simultaneous, serial capture of three different cell lines. In this case the device showed effective capture of cells in a single separation channel, opening up the possibility of multiple cell sorting. Multi-parameter sequential blood sample analysis was also demonstrated with high capture specificity (>97% for both CD19+ and CD4+ leukocytes). The chip can also be used to selectively treat cells after affinity separation. PMID:22958145

  9. Visualization of soft tissues by highly sensitive X-ray crystal analyzer-based multi diffraction enhanced imaging

    NASA Astrophysics Data System (ADS)

    Wu, Yanlin; Sunaguchi, Naoki; Lin, Xiaojie; Wang, Yongting; Yuasa, Tetsuya; Hirano, Keiichi; Hyodo, Kazuyuki

    2015-09-01

    In this paper, we propose a novel multi diffraction enhanced imaging (MDEI) technique to improve contrast resolution owning to the sharp rise of the reflectivity curve and high contrast-to-noise ratio (CNR). MDEI is derived from the diffraction enhanced imaging (DEI) technique. Here, DEI and MDEI phase contrast tomograms are compared. The results show that MDEI offers higher contrast resolution, while DEI has higher spatial resolution. This study provided indications for developments and applications of X-ray crystal analyzer-based imaging to obtain a higher contrast resolution.

  10. FPGA-based multi-channel fluorescence lifetime analysis of Fourier multiplexed frequency-sweeping lifetime imaging

    PubMed Central

    Zhao, Ming; Li, Yu; Peng, Leilei

    2014-01-01

    We report a fast non-iterative lifetime data analysis method for the Fourier multiplexed frequency-sweeping confocal FLIM (Fm-FLIM) system [ Opt. Express22, 10221 ( 2014)24921725]. The new method, named R-method, allows fast multi-channel lifetime image analysis in the system’s FPGA data processing board. Experimental tests proved that the performance of the R-method is equivalent to that of single-exponential iterative fitting, and its sensitivity is well suited for time-lapse FLIM-FRET imaging of live cells, for example cyclic adenosine monophosphate (cAMP) level imaging with GFP-Epac-mCherry sensors. With the R-method and its FPGA implementation, multi-channel lifetime images can now be generated in real time on the multi-channel frequency-sweeping FLIM system, and live readout of FRET sensors can be performed during time-lapse imaging. PMID:25321778

  11. Multi-ion free energy landscapes underscore the microscopic mechanism of ion selectivity in the KcsA channel.

    PubMed

    Medovoy, David; Perozo, Eduardo; Roux, Benoît

    2016-07-01

    Potassium (K(+)) channels are transmembrane proteins that passively and selectively allow K(+) ions to flow through them, after opening in response to an external stimulus. One of the most critical functional aspects of their function is their ability to remain very selective for K(+) over Na(+) while allowing high-throughput ion conduction at a rate close to the diffusion limit. Classically, it is assumed that the free energy difference between K(+) and Na(+) in the pore relative to the bulk solution is the critical quantity at the origin of selectivity. This is the thermodynamic view of ion selectivity. An alternative view assumes that kinetic factors play the dominant role. Recent results from a number of studies have also highlighted the great importance of the multi-ion single file on the selectivity of K(+) channels. The data indicate that having multiple K(+) ions bound simultaneously is required for selective K(+) conduction, and that a reduction in the number of bound K(+) ions destroys the multi-ion selectivity mechanism utilized by K(+) channels. In the present study, multi-ion potential of mean force molecular dynamics computations are carried out to clarify the mechanism of ion selectivity in the KcsA channel. The computations show that the multi-ion character of the permeation process is a critical element for establishing the selective ion conductivity through K(+)-channels. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov. PMID:26896693

  12. Multi-ion free energy landscapes underscore the microscopic mechanism of ion selectivity in the KcsA channel

    PubMed Central

    Medovoy, David; Perozo, Eduardo; Roux, Benoît

    2016-01-01

    Potassium (K+) channels are transmembrane proteins that passively and selectively allow K+ ions to flow through them, after opening in response to an external stimulus. One of the most critical functional aspects of their function is their ability to remain very selective for K+ over Na+ while allowing high-throughput ion conduction at a rate close to the diffusion limit. Classically, it is assumed that the free energy difference between K+ and Na+ in the pore relative to the bulk solution is the critical quantity at the origin of selectivity. This is the thermodynamic view of ion selectivity. An alternative view assumes that kinetic factor play the dominant role. Recent results from a number of studies have also highlighted the great importance of the multi-ion single file on the selectivity of K+ channels. The data indicate that having multiple K+ ions bound simultaneously is required for selective K+ conduction, and that a reduction in the number of bound K+ ions destroys the multi-ion selectivity mechanism utilized by K+ channels. In the present study, multi-ion potential of mean force molecular dynamics computations are carried out to clarify the mechanism of ion selectivity in the KcsA channel. The computations show that the multi-ion character of the permeation process is a critical element for establishing the selective ion conductivity through K+-channels. PMID:26896693

  13. Turbulent mixing of plasma and electrolyte in the multi-channel discharge between a droplet and electrolyte

    NASA Astrophysics Data System (ADS)

    Kayumov, R. R.; Gaysin, Al F.; Son, E. E.; Gaysin, Az F.; Gaysin, F. M.

    2010-12-01

    The multi-channel discharge between an electrolyte cathode and an electrolyte anode is of significant scientific and practical importance. The physical properties and characteristics of these types of discharges at atmospheric pressure have not yet been studied. This paper is devoted to the study of the multi-channel discharge between an electrolyte droplet cathode and an electrolyte cell anode. The experiments were carried out in the current range of 0.01-1.5 A and the voltage range of 50-1300 V. The flow rate of the droplet forming electrolyte was 0.2 g s-1. A NaCl solution was used as electrolyte.

  14. All-optical multi-channel wavelength conversion of Nyquist 16 QAM signal using a silicon waveguide.

    PubMed

    Long, Yun; Liu, Jun; Hu, Xiao; Wang, Andong; Zhou, Linjie; Zou, Kaiheng; Zhu, Yixiao; Zhang, Fan; Wang, Jian

    2015-12-01

    We experimentally demonstrate on-chip all-optical multi-channel wavelength conversion of Nyquist 16 ary quadrature amplitude modulation (16 QAM) signal in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼2  dB. The observed constellations of converted idlers indicate favorable performance of silicon-waveguide-based multi-channel wavelength conversion. We also experimentally study and compare the phase-conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in the silicon waveguide. PMID:26625029

  15. Multi-channel analysis of surface waves MASW of models with high shear-wave velocity contrast

    USGS Publications Warehouse

    Ivanov, J.; Miller, R.D.; Peterie, S.; Zeng, C.; Xia, J.; Schwenk, T.

    2011-01-01

    We use the multi-channel analysis of surface waves MASW method to analyze synthetic seismic data calculated using models with high shear-wave velocity Vs contrast. The MASW dispersion-curve images of the Rayleigh wave are obtained using various sets of source-offset and spread-size configurations from the synthetic seismic data and compared with the theoretically calculated fundamental- and higher-mode dispersion-curves. Such tests showed that most of the dispersion-curve images are dominated by higher-mode energy at the low frequencies, especially when analyzing data from long receiver offsets and thus significantly divert from numerically expected dispersion-curve trends, which can lead to significant Vs overestimation. Further analysis showed that using data with relatively short spread lengths and source offsets can image the desired fundamental-mode of the Rayleigh wave that matches the numerically expected dispersion-curve pattern. As a result, it was concluded that it might be possible to avoid higher-mode contamination at low frequencies at sites with high Vs contrast by appropriate selection of spread size and seismic source offset. ?? 2011 Society of Exploration Geophysicists.

  16. Non-locally regularized segmentation of multiple sclerosis lesion from multi-channel MRI data

    PubMed Central

    Gao, Jingjing; Li, Chunming; Feng, Chaolu; Xie, Mei; Yin, Yilong; Davatzikos, Christos

    2015-01-01

    Segmentation of multiple sclerosis (MS) lesion is important for many neuroimaging studies. In this paper, we propose a novel algorithm for automatic segmentation of MS lesions from multi-channel MR images (T1W, T2W and FLAIR images). The proposed method is an extension of Li et al.'s algorithm in [1], which only segments the normal tissues from T1W images. The proposed method is aimed to segment MS lesions, while normal tissues are also segmented and bias field is estimated to handle intensity inhomogeneities in the images. Another contribution of this paper is the introduction of a nonlocal means technique to achieve spatially regularized segmentation, which overcomes the influence of noise. Experimental results have demonstrated the effectiveness and advantages of the proposed algorithm. PMID:24948583

  17. MS lesion segmentation using a multi-channel patch-based approach with spatial consistency

    NASA Astrophysics Data System (ADS)

    Mechrez, Roey; Goldberger, Jacob; Greenspan, Hayit

    2015-03-01

    This paper presents an automatic method for segmentation of Multiple Sclerosis (MS) in Magnetic Resonance Images (MRI) of the brain. The approach is based on similarities between multi-channel patches (T1, T2 and FLAIR). An MS lesion patch database is built using training images for which the label maps are known. For each patch in the testing image, k similar patches are retrieved from the database. The matching labels for these k patches are then combined to produce an initial segmentation map for the test case. Finally a novel iterative patch-based label refinement process based on the initial segmentation map is performed to ensure spatial consistency of the detected lesions. A leave-one-out evaluation is done for each testing image in the MS lesion segmentation challenge of MICCAI 2008. Results are shown to compete with the state-of-the-art methods on the MICCAI 2008 challenge.

  18. [Multi-channel data collection and visualization system for intramyocardial electrograms].

    PubMed

    Kastner, P; Wimmer, W; Hutten, H

    2000-11-01

    The aim of the project was to develop a multichannel data acquisition system for the recording and visualisation of intramyocardial electrograms (IEGM) from both the spontaneously beating and the artificially paced heart. Signal processing comprises multi-step amplification, filtering (0.05-800 Hz), and AD conversion (12 Bit max. 6.25 kHz). IEGMs can be obtained either in unipolar or bipolar mode. Stimulation of the heart is achieved by an incorporated programmable dual-chamber pacemaker that can be selectively switched to the input channels. A LabView-based graphical user interface permits the programming of all system parameters via a microcontroller, and supports data acquisition and visualisation. The system can be used in animal experiments to monitor the spread of excitation across the heart, to measure propagation velocity, or to measure the impact of drugs and pathological changes on the morphology of IEGMs. PMID:11155534

  19. Design of a multi-channel free space optical interconnection component

    NASA Astrophysics Data System (ADS)

    Jia, Da-Gong; Zhang, Pei-Song; Jing, Wen-Cai; Tan, Jun; Zhang, Hong-Xia; Zhang, Yi-Mo

    2008-11-01

    A multi-channel free space optical interconnection component, fiber optic rotary joint, was designed using a Dove prism. When the Dove prism is rotated an angle of α around the longitudinal axis, the image rotates an angle of 2 α. The optical interconnection component consists of the signal transmission system, Dove prim and driving mechanism. The planetary gears are used to achieve the speed ratio of 2:1 between the total optical interconnection component and the Dove prism. The C-lenses are employed to couple different optical signals in the signal transmission system. The coupling loss between the receiving fiber of stationary part and the transmitting fiber of rotary part is measured.

  20. Scalable screen-size enlargement by multi-channel viewing-zone scanning holography.

    PubMed

    Takaki, Yasuhiro; Nakaoka, Mitsuki

    2016-08-01

    Viewing-zone scanning holographic displays can enlarge both the screen size and the viewing zone. However, limitations exist in the screen size enlargement process even if the viewing zone is effectively enlarged. This study proposes a multi-channel viewing-zone scanning holographic display comprising multiple projection systems and a planar scanner to enable the scalable enlargement of the screen size. Each projection system produces an enlarged image of the screen of a MEMS spatial light modulator. The multiple enlarged images produced by the multiple projection systems are seamlessly tiled on the planar scanner. This screen size enlargement process reduces the viewing zones of the projection systems, which are horizontally scanned by the planar scanner comprising a rotating off-axis lens and a vertical diffuser to enlarge the viewing zone. A screen size of 7.4 in. and a viewing-zone angle of 43.0° are demonstrated. PMID:27505840

  1. A method of multi-channel reference signals acquiring in broadband ANC

    NASA Astrophysics Data System (ADS)

    Ma, Ling-Kun; Huang, Jian-Guo; Zhang, Li-Jie

    2008-09-01

    In a flank array on an unmanned underwater vehicle (UUV), self-generated noise which has broadband and colored spectrum property in frequency and spatial domain is the main factor affecting the performance of weak signal detection, so the technique of adaptive noise cancellation (ANC) as well as physical denoising and active noise cancellation are often used in practice. Because ANC is based on correlations, improvements in performance come from better correlation between reference signals and primary signals. Taking full advantage of the characteristics of flank arrays and the characteristics of information obtained from hydrophones, a new method for reference signal acquisition for adaptive noise cancellation is proposed, in which the multi-channel reference signals are obtained by accurate delaying for a given direction of arrival (DOA) and differencing between adjacent outputs of array elements. The validity of the proposed method was verified through system modeling simulations and lake experiments which showed good performance with little additional computational burden.

  2. Boresonic testing utilizing multi-channel C-scan imaging in real time

    SciTech Connect

    Porter, J.P.; Morrison, J.W.

    1994-12-31

    Boreside nondestructive inspection techniques capable of detecting small, yet potentially dangerous flaws in turbine/generator rotors have been developed and utilized for several years. Test methods have ranged from simple hand scanning to very complex computer driven data acquisition systems. Under the direction of Northeast Inspection Services, Inc., an automated computer controlled ultrasonic recording apparatus (ACCURA) system has been developed, evaluated by EPRI, and utilized in the field to perform boresonic tests. The system provides real time multi-channel C-scan imaging of ultrasonic reflectors. Numerical data table files are stored in ASCII format for use in engineering analyses for flaw evaluation and lifetime prediction. A number of applications ranging from turbine rotor tests for detection of near bore indications to peripheral circumferential crack detection in generator rotors are described to illustrate the versatility of the system. The sensitivity and detection reliability of the system are also discussed.

  3. Multi-Channel Magnetocardiogardiography System Based on Low-Tc SQUIDs in an Unshielded Environment

    NASA Astrophysics Data System (ADS)

    Kong, Xiangyan; Zhang, Shulin; Wang, Yongliang; Zeng, Jia; Xie, Xiaoming

    Magnetocardiography (MCG) using superconducting quantum interference devices (SQUIDs) is a new medical diagnostic tool measuring biomagnetic signals that are generated by the electrical activity of the human heart. This technique is completely passive, contactless, and it has an advantage in the early diagnosis of heart diseases. We developed the first unshielded four-channel MCG system based on low-Tc DC SQUIDs in China. Instead of using a costly magnetically shielded room, the environmental noise suppression was realized by using second-order gradiometers and three-axis reference magnetometer. The measured magnetic field resolution of the system is better than 1 pT, and multi-cycle human heart signals can be recorded directly. Also, with the infrared positioning system, 48 points data collection can be realized by moving the non-magnetic bed nine times.

  4. Telephone speech enhancement for hearing-impaired listeners using multi-channel compression

    NASA Astrophysics Data System (ADS)

    Natarajan, Harikrishna P.; Krishnamurthy, Ashok K.; Feth, Lawrence L.

    2002-05-01

    Elderly listeners with sensorineural hearing impairment usually have difficulty with telephone communication if they do not use a hearing aid or telephone amplifier. In many cases, these devices may not be readily available or maybe uncomfortable to use. We describe here an alternative strategy to enhance the speech by pre-processing the signal before sending it over the telephone line. The pre-processing is based on a multi-channel compression algorithm that modifies the critical band spectrum of the speech signal to bring it within the dynamic hearing range of the listener, while also compensating for the effects of the telephone line. We describe the algorithm and the results of a simulation study in which the Articulation Index (AI) is used to measure the intelligibility enhancement, and the Glasberg, Moore and Stone (1999) model is used to simulate the effects of the hearing loss.

  5. Signal Detection of Multi-Channel Capillary Electrophoresis Chip Based on CCD

    NASA Astrophysics Data System (ADS)

    Lv, Hongfeng; Yan, Weiping; Yang, Xiaobo; Li, Jiechao; Zhu, Jieying

    2012-12-01

    A kind of multi-channel capillary electrophoresis (CE) chip signal detection system based on CCD was developed. The output signal of the CCD sensor was processed by a series of pre-processing circuits and ADC, and then it was collected by the Field Programmable Gate Array (FPGA) chip which communicated with a host computer. The core in FPGA was designed to control the signal flow of the CCD and transfer the data to PC based on a Nios II embedded soft-processor. The application of PC was used to store the data and demonstrate the curve. The measurement of the fluorescent signals for different concentration Rhodamine B dyes is presented and the comparison with other detection systems is also discussed.

  6. Multi-channel wireless mapping of gastrointestinal serosal slow wave propagation

    PubMed Central

    Paskaranandavadivel, Niranchan; Wang, Rui; Sathar, Shameer; O’Grady, Gregory; Cheng, Leo K; Farajidavar, Aydin

    2015-01-01

    Background High-resolution (HR) extracellular mapping allows accurate profiling of normal and dysrhythmic slow wave patterns. A current limitation is that cables traverse the abdominal wall or a natural orifice, risking discomfort, dislodgement or infection. Wireless approaches offer advantages, but a multi-channel system is required, capable of recording slow waves and mapping propagation with high fidelity. Methods A novel multi-channel (n=7) wireless mapping system was developed and compared to a wired commercial system. Slow wave signals were recorded from the porcine gastric and intestinal serosa in-vivo. Signals were simultaneously acquired using both systems, and were filtered and processed to map activation wavefronts. For validation, the frequency and amplitude of detected events were compared, together with the speed and direction of mapped wavefronts. Key Results The wireless device achieved comparable signal quality to the reference device, and slow wave frequencies were identical. Amplitudes of the acquired gastric and intestinal slow wave signals were consistent between the devices. During normal propagation, spatiotemporal mapping remained accurate in the wireless system, however, during ectopic dysrhythmic pacemaking, the lower sampling resolution of the wireless device led to reduced accuracy in spatiotemporal mapping. Conclusions and Inferences A novel multichannel wireless device is presented for mapping slow wave activity. The device achieved high quality signals, and has the potential to facilitate chronic monitoring studies and clinical translation of spatiotemporal mapping. The current implementation may be applied to detect normal patterns and dysrhythmia onset, but HR mapping with finely spaced arrays currently remains necessary to accurately define dysrhythmic patterns. PMID:25599978

  7. Estimation of black carbon content for biomass burning aerosols from multi-channel Raman lidar data

    NASA Astrophysics Data System (ADS)

    Talianu, Camelia; Marmureanu, Luminita; Nicolae, Doina

    2015-04-01

    Biomass burning due to natural processes (forest fires) or anthropical activities (agriculture, thermal power stations, domestic heating) is an important source of aerosols with a high content of carbon components (black carbon and organic carbon). Multi-channel Raman lidars provide information on the spectral dependence of the backscatter and extinction coefficients, embedding information on the black carbon content. Aerosols with a high content of black carbon have large extinction coefficients and small backscatter coefficients (strong absorption), while aerosols with high content of organic carbon have large backscatter coefficients (weak absorption). This paper presents a method based on radiative calculations to estimate the black carbon content of biomass burning aerosols from 3b+2a+1d lidar signals. Data is collected at Magurele, Romania, at the cross-road of air masses coming from Ukraine, Russia and Greece, where burning events are frequent during both cold and hot seasons. Aerosols are transported in the free troposphere, generally in the 2-4 km altitude range, and reaches the lidar location after 2-3 days. Optical data are collected between 2011-2012 by a multi-channel Raman lidar and follows the quality assurance program of EARLINET. Radiative calculations are made with libRadTran, an open source radiative model developed by ESA. Validation of the retrievals is made by comparison to a co-located C-ToF Aerosol Mass Spectrometer. Keywords: Lidar, aerosols, biomass burning, radiative model, black carbon Acknowledgment: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project no. 39/2012 - SIAFIM, and by Romanian Partnerships in priority areas PNII implemented with MEN-UEFISCDI support, project no. 309/2014 - MOBBE

  8. The multi-channel cochlear implant: past, present and future perspectives.

    PubMed

    Clark, Graeme

    2009-01-01

    Initial research demonstrated that only low frequencies could be mimicked with rate of electrical stimulation, and thus multi-channel rather than single-channel stimulation was required for the place coding of the mid-high speech frequencies. Place coding of mid-high frequencies was best achieved with electrodes inside the cochlea. Furthermore, correct biomechanical properties of a multiple electrode bundle were required for it to pass around the cochlear spiral to the speech frequency region. Biological studies showed too that intra-cochlear electrodes could be used with minimal trauma, safe electrical stimulus parameters, and methods to prevent inner ear infection and meningitis. The crucial discoveries for coding speech with electrical stimulation have been based on the discovery of: 1) the fact the brain processes frequency information along spatial and temporal channels, and 2) that the first patient experienced vowels when stimulating different electrodes that corresponded to the place of excitation for single formant vowels in people with normal hearing. The inaugural and subsequent speech processing strategies extracted frequencies of special importance for speech intelligibility, and transmitted the information along place coding channels. The voicing frequency and/or amplitude, was coded as temporal information across these spatial channels. As a result a great majority of severely-to-profoundly deaf people with previous hearing can not only communicate when electrical stimulation is combined with lipreading, but with electrical stimulation alone. In addition, the benefits of binaural hearing with bilateral cochlear implants or an implant in one ear and hearing aid in the other ear have been realized. Related psychophysical research has discovered the basic perceptual skills that process the complex patterns of brain excitation that underlie speech recognition both in the one ear as well as bilateral implants.In addition the development of the perceptual

  9. A modular architecture for multi-channel external cavity quantum cascade laser-based chemical sensors: a systems approach

    SciTech Connect

    Taubman, Matthew S.; Myers, Tanya L.; Bernacki, Bruce E.; Stahl, Robert D.; Cannon, Bret D.; Schiffern, John T.; Phillips, Mark C.

    2012-04-01

    A multi-channel laser-based chemical sensor platform is presented, in which a modular architecture allows the exchange of complete sensor channels without disruption to overall operation. Each sensor channel contains custom optical and electronics packages, which can be selected to access laser wavelengths, interaction path lengths and modulation techniques optimal for a given application or mission. Although intended primarily to accommodate mid-infrared (MIR) external cavity quantum cascade lasers (ECQCLs)and astigmatic Herriott cells, channels using visible or near infrared (NIR) lasers or other gas cell architectures can also be used, making this a truly versatile platform. Analog and digital resources have been carefully chosen to facilitate small footprint, rapid spectral scanning, ow-noise signal recovery, failsafe autonomous operation, and in-situ chemometric data analysis, storage and transmission. Results from the demonstration of a two-channel version of this platform are also presented.

  10. Application of multi-channel photoelastic imaging technology in array type ultrasonic nondestructive testing

    NASA Astrophysics Data System (ADS)

    Fan, Zhen-zhong; Bi, Chao

    2015-08-01

    With the rapid development of modern nondestructive testing technologies, ultrasonic phased array and Ultrasonic array testing technology has been used widely, at the same time the propagation process of ultrasonic in the material becomes more and more complex. In order to make the ultrasonic propagation path become visible and researchers can observe the acoustic field directly, considering the properties of the ultrasonic as a stress wave, according to the theory of polarized light interference, a multi-channel dynamic photoelastic imaging system is developed successfully. The system can generate many kinds of focusing ultrasonic fields in optical specimen by controlling the ultrasonic transmission delay time of each equipment channel, and the system has the ability to simulate the acoustic field's focusing process of the ultrasonic phased array. The image shot by CCD camera reflects the propagation process of the acoustic field in the specimen, and the dynamic video is formed under control of the timing circuit, and the system has the ability to save the captured image in the computer.

  11. Automatic seizure detection based on the combination of newborn multi-channel EEG and HRV information

    NASA Astrophysics Data System (ADS)

    Mesbah, Mostefa; Balakrishnan, Malarvili; Colditz, Paul B.; Boashash, Boualem

    2012-12-01

    This article proposes a new method for newborn seizure detection that uses information extracted from both multi-channel electroencephalogram (EEG) and a single channel electrocardiogram (ECG). The aim of the study is to assess whether additional information extracted from ECG can improve the performance of seizure detectors based solely on EEG. Two different approaches were used to combine this extracted information. The first approach, known as feature fusion, involves combining features extracted from EEG and heart rate variability (HRV) into a single feature vector prior to feeding it to a classifier. The second approach, called classifier or decision fusion, is achieved by combining the independent decisions of the EEG and the HRV-based classifiers. Tested on recordings obtained from eight newborns with identified EEG seizures, the proposed neonatal seizure detection algorithms achieved 95.20% sensitivity and 88.60% specificity for the feature fusion case and 95.20% sensitivity and 94.30% specificity for the classifier fusion case. These results are considerably better than those involving classifiers using EEG only (80.90%, 86.50%) or HRV only (85.70%, 84.60%).

  12. The Research of China's Civil Aviation Passenger Multi-Channel Service Technology Platform

    NASA Astrophysics Data System (ADS)

    Zhibing, Xue; Xinming, Wang

    IATA is promoting Simplifying the Business. The traditional passenger services and business process, such as ticketing, airport counters, had a great influence. The airlines have the passenger service and convenience as the next product development requirements. With civil aviation industry and their company's products construction, the authors propose a solution of passenger multi-channel service product platform. The solution is to streamline the business as the breakthrough point, around the convenience of passengers travel services to travelers as the center, using the current mainstream and the latest IT technology to establish passenger service product platform. The solution will promote DCS e-ticketing business development and service channel diversity. In this paper, the research results have been applied in the product platform construction of the authors' company. The practice shows that through traditional business with the latest IT technologies, traditional passenger services into the emerging service model, passenger service product platform has strong advantages and characteristics. Based on the platform, various types of service products is growing rapidly.

  13. A low-offset analogue front-end IC for multi-channel physiological signal acquisition.

    PubMed

    Zhang, Jinyong; Wang, Lei; Yu, Li; Yang, Yabei; Zhang, Yuanting; Li, Bin

    2009-01-01

    This paper describes a low-offset analogue front-end (AFE) integrated circuit (IC) for multi-channel physiological signal acquisitions. The mixed signal IC consists of low-offset gain programmable instrumentation amplifiers (GPIAs), high sensitive current-to-voltage converters (I-V converters), reference and an 8-bit analogue-to-digital converter (ADC). The IC offered adjustable gains that were elaborated for various physiological signal acquisitions. The conditional signals were quantized by ADC that offered an optimal solution for portable applications. The circuit was fabricated in SMIC 0.18-mum mixed-signal CMOS technology, and core area of the whole IC measured 1.36 mm(2). The post-annotated simulations suggested that the system achieved a common-mode-rejection-ration (CMRR) of 142 dB, the adjustable gain from 31.6 dB to 76.5 dB, and the offset voltage less than 80 microV. The 8-bit ADC exhibited less than 0.8 LSB DNL and 1.1 LSB INL. Power dissipation of each channel and the ADC were approximately 348 microW and 1.65 mW under a 1.8 V single supply voltage, respectively. It is suitable for a wide range of high precision biomedical applications. PMID:19964636

  14. Fully automated analysis of multi-resolution four-channel micro-array genotyping data

    NASA Astrophysics Data System (ADS)

    Abbaspour, Mohsen; Abugharbieh, Rafeef; Podder, Mohua; Tebbutt, Scott J.

    2006-03-01

    We present a fully-automated and robust microarray image analysis system for handling multi-resolution images (down to 3-micron with sizes up to 80 MBs per channel). The system is developed to provide rapid and accurate data extraction for our recently developed microarray analysis and quality control tool (SNP Chart). Currently available commercial microarray image analysis applications are inefficient, due to the considerable user interaction typically required. Four-channel DNA microarray technology is a robust and accurate tool for determining genotypes of multiple genetic markers in individuals. It plays an important role in the state of the art trend where traditional medical treatments are to be replaced by personalized genetic medicine, i.e. individualized therapy based on the patient's genetic heritage. However, fast, robust, and precise image processing tools are required for the prospective practical use of microarray-based genetic testing for predicting disease susceptibilities and drug effects in clinical practice, which require a turn-around timeline compatible with clinical decision-making. In this paper we have developed a fully-automated image analysis platform for the rapid investigation of hundreds of genetic variations across multiple genes. Validation tests indicate very high accuracy levels for genotyping results. Our method achieves a significant reduction in analysis time, from several hours to just a few minutes, and is completely automated requiring no manual interaction or guidance.

  15. Development of a multi-channel time-domain fluorescence mammograph

    NASA Astrophysics Data System (ADS)

    Hagen, A.; Steinkellner, O.; Grosenick, D.; Möller, M.; Ziegler, R.; Nielsen, T.; Lauritsen, K.; Macdonald, R.; Rinneberg, H.

    2007-02-01

    We developed an eight-channel scanning time-domain fluorescence mammograph capable of imaging the distribution of a non-specific fluorescent contrast agent in the female breast, besides imaging intrinsic absorption and scattering properties of healthy breast tissue and tumors. The apparatus is based on the PTB multi-channel laser pulse mammograph, originally designed for measurements of absorption and scattering coefficients at four selected wavelengths (λ = 652 nm, 684 nm, 797nm, and 830 nm). It was upgraded for time-resolved detection of fluorescence, excited at 735 nm by a ps diode laser with 10 mW output power and detected at wavelengths λ >= 780 nm. Cooled PMTs with GaAs photocathodes are used to detect laser and fluorescence photons at five positions in transmission and three positions in reflection. Measurements are performed with the breast being slightly compressed between two parallel glass plates. The transmitting and receiving fiber bundles are scanned synchronously over the breast in steps of typically 2.5 mm. At each scan position, distributions of times of flight of laser photons are measured by time-correlated single photon counting at eight detector positions, followed by measurements of distributions of times of arrival of fluorescence photons. The performance of the fluorescence mammograph was investigated by using breast-like phantoms with a fluorescent inhomogeneity with dye enrichment varying between 2:1 and 10:1 over background values.

  16. Impairment of the Vascular KATP Channel Imposes Fatal Susceptibility to Experimental Diabetes Due to Multi-Organ Injuries.

    PubMed

    Li, Shan-Shan; Cui, Ningren; Yang, Yang; Trower, Timothy C; Wei, Yu-Min; Wu, Yang; Zhang, Shuang; Jin, Xin; Jiang, Chun

    2015-12-01

    The vascular isoform of ATP-sensitive K(+) (KATP ) channels regulates blood flow to all organs. The KATP channel is strongly inhibited by reactive oxygen and carbonyl species produced in diabetic tissue inflammation. To address how such channel inhibition impacts vascular regulation as well as tissue viability, we performed studies in experimental diabetic mice. Strikingly, we found that knockout of the Kcnj8 encoding Kir6.1 subunit (Kcnj8-KO) caused mice to be fatally susceptible to diabetes. Organ perfusion studies suggested that the lack of this vascular K(+) channel handicapped activity-dependent vasodilation, leading to hypoperfusion, tissue hypoxia, and multi-organ failure. Morphologically, Kcnj8-KO mice showed greater inflammatory cell infiltration, higher levels of expression of inflammation indicator proteins, more severe cell apoptosis, and worse tissue disruptions. These were observed in the kidney, liver, and heart under diabetic condition in parallel comparison to tissues from WT mice. Patch clamping and molecular studies showed that the KATP channel was S-glutathionylated in experimental diabetes contributing to the inhibition of channel activity as well as the reduced arterial responses to vasodilators. These results suggest that the vascular KATP channel is organ protective in diabetic condition, and since the channel is suppressed by diabetic oxidative stress, therapeutical interventions to the maintenance of functional KATP channels may help to lower or prevent diabetic organ dysfunction. PMID:25825210

  17. A Wireless Multi-Channel Recording System for Freely Behaving Mice and Rats

    PubMed Central

    Holtzman, Tahl; Ruther, Patrick; Dalley, Jeffrey W.; Lopez, Alberto; Rossi, Mark A.; Barter, Joseph W.; Salas-Meza, Daniel; Herwik, Stanislav; Holzhammer, Tobias; Morizio, James; Yin, Henry H.

    2011-01-01

    To understand the neural basis of behavior, it is necessary to record brain activity in freely moving animals. Advances in implantable multi-electrode array technology have enabled researchers to record the activity of neuronal ensembles from multiple brain regions. The full potential of this approach is currently limited by reliance on cable tethers, with bundles of wires connecting the implanted electrodes to the data acquisition system while impeding the natural behavior of the animal. To overcome these limitations, here we introduce a multi-channel wireless headstage system designed for small animals such as rats and mice. A variety of single unit and local field potential signals were recorded from the dorsal striatum and substantia nigra in mice and the ventral striatum and prefrontal cortex simultaneously in rats. This wireless system could be interfaced with commercially available data acquisition systems, and the signals obtained were comparable in quality to those acquired using cable tethers. On account of its small size, light weight, and rechargeable battery, this wireless headstage system is suitable for studying the neural basis of natural behavior, eliminating the need for wires, commutators, and other limitations associated with traditional tethered recording systems. PMID:21765934

  18. Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm

    NASA Astrophysics Data System (ADS)

    Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G.; Woodbury, Neal W.; Yan, Hao

    2014-07-01

    Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity.

  19. Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm.

    PubMed

    Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G; Woodbury, Neal W; Yan, Hao

    2014-07-01

    Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity. PMID:24859813

  20. Objective research and application of multi-channel human meridian impedance dynamic testing system

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhang, Jun; Jiao, Jianling

    2008-10-01

    This paper is an in-depth study on the basis of the passed summary of relevant technologies. Multi-channel ring electrode has been developed to point impedance testing of the human body for the first time. Here, we build such a system, which bases on the hardware platform of AT89C52 combined with M82C54-2, besides, the integrated software development tools micro-soft visual c++ and the technical advantages such as multi-threading, databases, serial communication and the characteristics of real-time supported by Windows XP are used in here too. Except for the point impedance testing of the human body, the conductive volume of the human meridian and infrared-photoelectric absorption properties of physical quantities can also be detected by such an on-site data acquisition, analysis, display, record and communicate with the PC portable System. Currently, the system was being in the testing phase, we have collected some real data of human body with this vehicle, whose results are expected to be more satisfactory in the near future.

  1. Non-local Atlas-guided Multi-channel Forest Learning for Human Brain Labeling

    PubMed Central

    Ma, Guangkai; Gao, Yaozong; Wu, Guorong; Wu, Ligang; Shen, Dinggang

    2015-01-01

    Labeling MR brain images into anatomically meaningful regions is important in many quantitative brain researches. In many existing label fusion methods, appearance information is widely used. Meanwhile, recent progress in computer vision suggests that the context feature is very useful in identifying an object from a complex scene. In light of this, we propose a novel learning-based label fusion method by using both low-level appearance features (computed from the target image) and high-level context features (computed from warped atlases or tentative labeling maps of the target image). In particular, we employ a multi-channel random forest to learn the nonlinear relationship between these hybrid features and the target labels (i.e., corresponding to certain anatomical structures). Moreover, to accommodate the high inter-subject variations, we further extend our learning-based label fusion to a multi-atlas scenario, i.e., we train a random forest for each atlas and then obtain the final labeling result according to the consensus of all atlases. We have comprehensively evaluated our method on both LONI-LBPA40 and IXI datasets, and achieved the highest labeling accuracy, compared to the state-of-the-art methods in the literature. PMID:26942235

  2. The multi-channel cochlear implant and the relief of severe-to-profound deafness.

    PubMed

    Clark, Graeme

    2012-05-01

    This personal reflection outlines the discoveries at the University of Melbourne leading to the multi-channel cochlear implant, and its development industrially by Cochlear Limited. My earlier experimental electrophysiological research demonstrated temporal coding occurred for only low frequencies, i.e. below 200-500 pulses/second. I was able to confirm these findings perceptually in behaviourally conditioned animals. In addition, these studies showed that temporal discrimination occurred across spatial coding channels. These experimental results correlated with the later conscious experience for electrical stimulation in my implant patients. In addition, the mid-to-high frequencies were coded in part by place of stimulation using bipolar and monopolar stimulation to restrict current spread. Furthermore, place of stimulation had the qualities of sharpness and dullness, and was also experienced as vowels. Owing to the limitation in coding speech with a physiological model due to the overlap of electrical current leading to unpredictable variations in loudness, a speech coding strategy that extracted the most important speech features for transmission through an electro-neural 'bottle-neck' to the brain was explored. Our inaugural strategy, discovered in 1978, extracted the second formant for place of stimulation, voicing for rate of stimulation, and sound pressure for current level. This was the first coding strategy to provide open-set speech understanding, as shown by standard audiological tests, and it became the first clinically successful interface between the world and human consciousness. This strategy was improved with place coding for the third formant or high-frequency spectrum, and then the spectral maxima. In 1989, I operated on our first patient to receive a bilateral implant, and in 1990, the first with a bimodal processor. The psychophysics and speech perception for these showed that the stimuli from each side could be fused into a single image, and

  3. Wireless multi-channel single unit recording in freely moving and vocalizing primates

    PubMed Central

    Roy, Sabyasachi; Wang, Xiaoqin

    2011-01-01

    The ability to record well-isolated action potentials from individual neurons in naturally behaving animals is crucial for understanding neural mechanisms underlying natural behaviors. Traditional neurophysiology techniques, however, require the animal to be restrained which often restricts natural behavior. An example is the common marmoset (Callithrix jacchus), a highly vocal New World primate species, used in our laboratory to study the neural correlates of vocal production and sensory feedback. When restrained by traditional neurophysiological techniques marmoset vocal behavior is severely inhibited. Tethered recording systems, while proven effective in rodents pose limitations in arboreal animals such as the marmoset that typically roam in a three-dimensional environment. To overcome these obstacles, we have developed a wireless neural recording technique that is capable of collecting single-unit data from chronically implanted multi-electrodes in freely moving marmosets. A lightweight, low power and low noise wireless transmitter (headstage) is attached to a multi-electrode array placed in the premotor cortex of the marmoset. The wireless headstage is capable of transmitting 15 channels of neural data with signal-to-noise ratio (SNR) comparable to a tethered system. To minimize radio-frequency (RF) and electro-magnetic interference (EMI), the experiments were conducted within a custom designed RF/EMI and acoustically shielded chamber. The individual electrodes of the multi-electrode array were periodically advanced to densely sample the cortical layers. We recorded single-unit data over a period of several months from the frontal cortex of two marmosets. These recordings demonstrate the feasibility of using our wireless recording method to study single neuron activity in freely roaming primates. PMID:21933683

  4. Collimating Montel mirror as part of a multi-crystal analyzer system for resonant inelastic X-ray scattering.

    PubMed

    Kim, Jungho; Shi, Xianbo; Casa, Diego; Qian, Jun; Huang, XianRong; Gog, Thomas

    2016-07-01

    Advances in resonant inelastic X-ray scattering (RIXS) have come in lockstep with improvements in energy resolution. Currently, the best energy resolution at the Ir L3-edge stands at ∼25 meV, which is achieved using a diced Si(844) spherical crystal analyzer. However, spherical analyzers are limited by their intrinsic reflection width. A novel analyzer system using multiple flat crystals provides a promising way to overcome this limitation. For the present design, an energy resolution at or below 10 meV was selected. Recognizing that the angular acceptance of flat crystals is severely limited, a collimating element is essential to achieve the necessary solid-angle acceptance. For this purpose, a laterally graded, parabolic, multilayer Montel mirror was designed for use at the Ir L3-absorption edge. It provides an acceptance larger than 10 mrad, collimating the reflected X-ray beam to smaller than 100 µrad, in both vertical and horizontal directions. The performance of this mirror was studied at beamline 27-ID at the Advanced Photon Source. X-rays from a diamond (111) monochromator illuminated a scattering source of diameter 5 µm, generating an incident beam on the mirror with a well determined divergence of 40 mrad. A flat Si(111) crystal after the mirror served as the divergence analyzer. From X-ray measurements, ray-tracing simulations and optical metrology results, it was established that the Montel mirror satisfied the specifications of angular acceptance and collimation quality necessary for a high-resolution RIXS multi-crystal analyzer system. PMID:27359136

  5. Task Dependent Prefrontal Dysfunction in Persons with Asperger's Disorder Investigated with Multi-Channel Near-Infrared Spectroscopy

    ERIC Educational Resources Information Center

    Iwanami, Akira; Okajima, Yuka; Ota, Haruhisa; Tani, Masayuki; Yamada, Takashi; Hashimoro, Ryuichiro; Kanai, Chieko; Watanabe, Hiromi; Yamasue, Hidenori; Kawakubo, Yuki; Kato, Nobumasa

    2011-01-01

    Dysfunction of the prefrontal cortex has been previously reported in individuals with Asperger's disorder. In the present study, we used multi-channel near-infrared spectroscopy (NIRS) to detect changes in the oxygenated hemoglobin concentration ([oxy-Hb]) during two verbal fluency tasks. The subjects were 20 individuals with Asperger's disorder…

  6. Complexity of Multi-Channel Electroencephalogram Signal Analysis in Childhood Absence Epilepsy

    PubMed Central

    Chang, Chi-Feng; Lu, Wen-Yu; Lin, Chun-Yen; Lee, Wang-Tso; Shieh, Jiann-Shing

    2015-01-01

    Absence epilepsy is an important epileptic syndrome in children. Multiscale entropy (MSE), an entropy-based method to measure dynamic complexity at multiple temporal scales, is helpful to disclose the information of brain connectivity. This study investigated the complexity of electroencephalogram (EEG) signals using MSE in children with absence epilepsy. In this research, EEG signals from 19 channels of the entire brain in 21 children aged 5-12 years with absence epilepsy were analyzed. The EEG signals of pre-ictal (before seizure) and ictal states (during seizure) were analyzed by sample entropy (SamEn) and MSE methods. Variations of complexity index (CI), which was calculated from MSE, from the pre-ictal to the ictal states were also analyzed. The entropy values in the pre-ictal state were significantly higher than those in the ictal state. The MSE revealed more differences in analysis compared to the SamEn. The occurrence of absence seizures decreased the CI in all channels. Changes in CI were also significantly greater in the frontal and central parts of the brain, indicating fronto-central cortical involvement of “cortico-thalamo-cortical network” in the occurrence of generalized spike and wave discharges during absence seizures. Moreover, higher sampling frequency was more sensitive in detecting functional changes in the ictal state. There was significantly higher correlation in ictal states in the same patient in different seizures but there were great differences in CI among different patients, indicating that CI changes were consistent in different absence seizures in the same patient but not from patient to patient. This implies that the brain stays in a homogeneous activation state during the absence seizures. In conclusion, MSE analysis is better than SamEn analysis to analyze complexity of EEG, and CI can be used to investigate the functional brain changes during absence seizures. PMID:26244497

  7. Complexity of Multi-Channel Electroencephalogram Signal Analysis in Childhood Absence Epilepsy.

    PubMed

    Weng, Wen-Chin; Jiang, George J A; Chang, Chi-Feng; Lu, Wen-Yu; Lin, Chun-Yen; Lee, Wang-Tso; Shieh, Jiann-Shing

    2015-01-01

    Absence epilepsy is an important epileptic syndrome in children. Multiscale entropy (MSE), an entropy-based method to measure dynamic complexity at multiple temporal scales, is helpful to disclose the information of brain connectivity. This study investigated the complexity of electroencephalogram (EEG) signals using MSE in children with absence epilepsy. In this research, EEG signals from 19 channels of the entire brain in 21 children aged 5-12 years with absence epilepsy were analyzed. The EEG signals of pre-ictal (before seizure) and ictal states (during seizure) were analyzed by sample entropy (SamEn) and MSE methods. Variations of complexity index (CI), which was calculated from MSE, from the pre-ictal to the ictal states were also analyzed. The entropy values in the pre-ictal state were significantly higher than those in the ictal state. The MSE revealed more differences in analysis compared to the SamEn. The occurrence of absence seizures decreased the CI in all channels. Changes in CI were also significantly greater in the frontal and central parts of the brain, indicating fronto-central cortical involvement of "cortico-thalamo-cortical network" in the occurrence of generalized spike and wave discharges during absence seizures. Moreover, higher sampling frequency was more sensitive in detecting functional changes in the ictal state. There was significantly higher correlation in ictal states in the same patient in different seizures but there were great differences in CI among different patients, indicating that CI changes were consistent in different absence seizures in the same patient but not from patient to patient. This implies that the brain stays in a homogeneous activation state during the absence seizures. In conclusion, MSE analysis is better than SamEn analysis to analyze complexity of EEG, and CI can be used to investigate the functional brain changes during absence seizures. PMID:26244497

  8. An Improved Cloud Classification Algorithm for China's FY-2C Multi-Channel Images Using Artificial Neural Network.

    PubMed

    Liu, Yu; Xia, Jun; Shi, Chun-Xiang; Hong, Yang

    2009-01-01

    The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China's first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are analyzed, together with the comparison of two other methods: Principal Component Analysis (PCA) and a Support Vector Machine (SVM), using 2864 cloud samples manually collected by meteorologists in June, July, and August in 2007 from three FY-2C channel (IR1, 10.3-11.3 μm; IR2, 11.5-12.5 μm and WV 6.3-7.6 μm) imagery. The result shows that: (1) ANN approaches, in general, outperformed the PCA and the SVM given sufficient training samples and (2) among the six ANN networks, higher cloud classification accuracy was obtained with the Self-Organizing Map (SOM) and Probabilistic Neural Network (PNN). Second, to compare the ANN methods to the present FY-2C operational algorithm, this study implemented SOM, one of the best ANN network identified from this study, as an automated cloud classification system for the FY-2C multi-channel data. It shows that SOM method has improved the results greatly not only in pixel-level accuracy but also in cloud patch-level classification by more accurately identifying cloud types such as cumulonimbus, cirrus and clouds in high latitude. Findings of this study suggest that the ANN-based classifiers, in particular the SOM, can be potentially used as an improved Automated Cloud Classification Algorithm to upgrade the current window-based clustering method for the FY-2C operational products. PMID:22346714

  9. An Improved Cloud Classification Algorithm for China’s FY-2C Multi-Channel Images Using Artificial Neural Network

    PubMed Central

    Liu, Yu; Xia, Jun; Shi, Chun-Xiang; Hong, Yang

    2009-01-01

    The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China’s first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are analyzed, together with the comparison of two other methods: Principal Component Analysis (PCA) and a Support Vector Machine (SVM), using 2864 cloud samples manually collected by meteorologists in June, July, and August in 2007 from three FY-2C channel (IR1, 10.3–11.3 μm; IR2, 11.5–12.5 μm and WV 6.3–7.6 μm) imagery. The result shows that: (1) ANN approaches, in general, outperformed the PCA and the SVM given sufficient training samples and (2) among the six ANN networks, higher cloud classification accuracy was obtained with the Self-Organizing Map (SOM) and Probabilistic Neural Network (PNN). Second, to compare the ANN methods to the present FY-2C operational algorithm, this study implemented SOM, one of the best ANN network identified from this study, as an automated cloud classification system for the FY-2C multi-channel data. It shows that SOM method has improved the results greatly not only in pixel-level accuracy but also in cloud patch-level classification by more accurately identifying cloud types such as cumulonimbus, cirrus and clouds in high latitude. Findings of this study suggest that the ANN-based classifiers, in particular the SOM, can be potentially used as an improved Automated Cloud Classification Algorithm to upgrade the current window-based clustering method for the FY-2C operational products. PMID:22346714

  10. MULTICHANNEL ANALYZER

    DOEpatents

    Kelley, G.G.

    1959-11-10

    A multichannel pulse analyzer having several window amplifiers, each amplifier serving one group of channels, with a single fast pulse-lengthener and a single novel interrogation circuit serving all channels is described. A pulse followed too closely timewise by another pulse is disregarded by the interrogation circuit to prevent errors due to pulse pileup. The window amplifiers are connected to the pulse lengthener output, rather than the linear amplifier output, so need not have the fast response characteristic formerly required.

  11. Performance improvement of FSO/CDMA systems over dispersive turbulence channel using multi-wavelength PPM signaling.

    PubMed

    Dang, Ngoc T; Pham, Anh T

    2012-11-19

    Previous studies show that, compared to on-off keying (OOK) signaling, pulse-position modulation (PPM) is favorable in FSO/CDMA systems thanks to its energy efficiency and simple detection. Nevertheless, when the system bit rate increases and the transmission distance is far, the FSO/CDMA systems using PPM signaling critically suffer from the impact of pulse broadening caused by dispersion, especially when the modulation level is high. In this paper, we therefore propose to use multi-wavelength PPM (MWPPM) signaling to overcome the limitation of PPM. To further improve the system performance, avalanche photodiode (APD) is also used. The performance of the proposed system is theoretically analyzed using a realistic model of Gaussian pulse propagation. To model the impact of intensity fluctuation caused by the atmospheric turbulence, the log-normal channel is used. We find that, by using MWPPM, the effects of both intensity fluctuation and pulse broadening are mitigated, the BER is therefore significantly improved. Additionally, we quantitatively show that the system performance is further improved by using APD, especially when the average APD gain is chosen properly. PMID:23187533

  12. PAD-MAC: Primary User Activity-Aware Distributed MAC for Multi-Channel Cognitive Radio Networks

    PubMed Central

    Ali, Amjad; Piran, Md. Jalil; Kim, Hansoo; Yun, Jihyeok; Suh, Doug Young

    2015-01-01

    Cognitive radio (CR) has emerged as a promising technology to solve problems related to spectrum scarcity and provides a ubiquitous wireless access environment. CR-enabled secondary users (SUs) exploit spectrum white spaces opportunistically and immediately vacate the acquired licensed channels as primary users (PUs) arrive. Accessing the licensed channels without the prior knowledge of PU traffic patterns causes severe throughput degradation due to excessive channel switching and PU-to-SU collisions. Therefore, it is significantly important to design a PU activity-aware medium access control (MAC) protocol for cognitive radio networks (CRNs). In this paper, we first propose a licensed channel usage pattern identification scheme, based on a two-state Markov model, and then estimate the future idle slots using previous observations of the channels. Furthermore, based on these past observations, we compute the rank of each available licensed channel that gives SU transmission success assessment during the estimated idle slot. Secondly, we propose a PU activity-aware distributed MAC (PAD-MAC) protocol for heterogeneous multi-channel CRNs that selects the best channel for each SU to enhance its throughput. PAD-MAC controls SU activities by allowing them to exploit the licensed channels only for the duration of estimated idle slots and enables predictive and fast channel switching. To evaluate the performance of the proposed PAD-MAC, we compare it with the distributed QoS-aware MAC (QC-MAC) and listen-before-talk MAC schemes. Extensive numerical results show the significant improvements of the PAD-MAC in terms of the SU throughput, SU channel switching rate and PU-to-SU collision rate. PMID:25831084

  13. PAD-MAC: primary user activity-aware distributed MAC for multi-channel cognitive radio networks.

    PubMed

    Ali, Amjad; Piran, Md Jalil; Kim, Hansoo; Yun, Jihyeok; Suh, Doug Young

    2015-01-01

    Cognitive radio (CR) has emerged as a promising technology to solve problems related to spectrum scarcity and provides a ubiquitous wireless access environment. CR-enabled secondary users (SUs) exploit spectrum white spaces opportunistically and immediately vacate the acquired licensed channels as primary users (PUs) arrive. Accessing the licensed channels without the prior knowledge of PU traffic patterns causes severe throughput degradation due to excessive channel switching and PU-to-SU collisions. Therefore, it is significantly important to design a PU activity-aware medium access control (MAC) protocol for cognitive radio networks (CRNs). In this paper, we first propose a licensed channel usage pattern identification scheme, based on a two-state Markov model, and then estimate the future idle slots using previous observations of the channels. Furthermore, based on these past observations, we compute the rank of each available licensed channel that gives SU transmission success assessment during the estimated idle slot. Secondly, we propose a PU activity-aware distributed MAC (PAD-MAC) protocol for heterogeneous multi-channel CRNs that selects the best channel for each SU to enhance its throughput. PAD-MAC controls SU activities by allowing them to exploit the licensed channels only for the duration of estimated idle slots and enables predictive and fast channel switching. To evaluate the performance of the proposed PAD-MAC, we compare it with the distributed QoS-aware MAC (QC-MAC) and listen-before-talk MAC schemes. Extensive numerical results show the significant improvements of the PAD-MAC in terms of the SU throughput, SU channel switching rate and PU-to-SU collision rate. PMID:25831084

  14. The Impact of the AIRS Spatial Response on Channel-to-Channel and Multi-Instrument Data Analyses

    NASA Technical Reports Server (NTRS)

    Elliott, Denis A.; Pagano, Thomas S.; Aumann, H. H.

    2006-01-01

    The Atmospheric Infrared Sounder (AIRS) measures the infrared spectrum in 2378 channels between 3.7 and 15.4 microns with a very high spectral resolution of approximately 1200. AIRS footprints are approximately 1.1 by 0.6 degrees. Because AIRS is a grating spectrometer, each channel has a unique spatial response. Image rotation due to the scan mirror causes these spatial responses to rotate. In effect, each channel has 90 spatial responses, one for each scene footprint in the scan line. Although the spatial response for most channels is symmetric and nearly uniform, some channels have significantly asymmetric response. This paper reviews and describes the prelaunch measurements that characterized the spatial response functions. Next, it describes the conversion of the ground-based results into footprint-specific response functions valid in flight. Then we describe the postlaunch validation of the measurements, including centroid location, axes orientations, and a check on the full two-dimensional response functions. This latter check involves comparison of AIRS data with that of the Moderate Resolution Imaging Spectrometer (MODIS), which flies on the same platform as AIRS. An important result is that AIRS/MODIS brightness temperature comparisons are significantly improved (scatter reduced) when the AIRS spatial response is explicitly taken into account. Finally, a status report is given on attempts to fully verify the prelaunch measurements by deriving the AIRS spatial response from flight data alone.

  15. Retrievals on Tropical small scale humidity variability from multi-channel microwave radiometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhao; Zuidema, Paquita; Turner, David

    2016-04-01

    Small-scale atmospheric humidity structure is important to many atmospheric process studies. In the Tropics especially, convection is sensitive to small variations in humidity. High temporal-resolution humidity profiles and spatially-resolved humidity fields are valuable for understanding the relationship of convection to tropical humidity, such as at convectively-induced cold pools and as part of the shallow-to-deep cloud transition. Radiosondes can provide high resolution vertical profiles of temperature and humidity, but are relatively infrequent. Microwave radiometers (MWR) are able to profile and scan autonomously and output measurements frequently (~1 Hz). To date, few assessments of microwave humidity profiling in the Tropics have been undertaken. Löhnert et al. (2009) provide one evaluation for Darwin, Australia. We build on this using four months of data from the equatorial Indian Ocean, at Gan Island, collected from University of Miami's (UM) multi-channel radiometer during the Dynamics of Madden-Julian Oscillation (DYNAMO) field campaign. Liquid Water Path (LWP) and Water Vapor Path (WVP) are physically retrieved using the MWR RETrieval (MWRRET) algorithm (Turner et al., 2007b), and humidity profiles in the tropics are retrieved using the Integrated Profiling Technique (Löhnert et al., 2004). Tropical temperature variability is weak and a climatological temperature profile is assumed, with humidity information drawn from five channels between 22 to 30 GHz. Scanning measurements were coordinated with the scanning pattern of NCAR's S-Pol-Ka radar. An analysis of the humidity information content gathered from both the profiling and scanning measurements will be presented.

  16. Development of a multi-channel readout ASIC for a fast neutron spectrometer based on GEM-TPC

    NASA Astrophysics Data System (ADS)

    He, Li; Deng, Zhi; Liu, Yi-Nong; Li, Yu-Lan

    2014-10-01

    A multi-channel front-end ASIC has been developed for a fast neutron spectrometer based on Gas Electron Multiplier (GEM)-Time Projection Chamber (TPC). Charge Amplifier and Shaping Amplifier for GEM (CASAGEM) integrates 16+1 channels: 16 channels for anodes and 1 channel for cathode. The gain and the shaping time are adjustable from 2 to 40 mV/fC and from 20 to 80 ns, respectively. The prototype ASIC is fabricated in 0.35 μm CMOS process. An evaluation Print Circuit Board (PCB) was also developed for chip tests. In total 20 chips have been tested. The integrated nonlinearity is less than 1%. The equivalent noise electrons is less than 2000e when the input capacitor is 50 pF. The time jitter is less than 1 ns. The design and the test results are presented in the paper.

  17. Enabling Technology for the Exploration of the Arctic Ocean - Multi Channel Seismic Reflection data acquisition

    NASA Astrophysics Data System (ADS)

    Coakley, B.; Anderson, R.; Chayes, D. N.; Goemmer, S.; Oursler, M.

    2009-12-01

    Great advances in mapping the Arctic Ocean have recently been made through the relatively routine acquisition of multibeam data from icebreakers operating on various cruise. The USCGC Healy, the German icebreaker Polarstern, the Canadian icebreaker Amundsen and the Swedish icebreaker Oden all routinely collect multibeam data, even while in heavy ice pack. This increase in data has substantially improved our knowledge of the form of the Arctic Ocean seafloor. Unfortunately, it is not possible to routinely collect Multi Channel Seismic Reflection (MCS) data while underway in the ice pack. Our inability to simply collect these data restricts how we understand many of the features that segment the basin by depriving us of the historical information that can be obtained by imaging the stratigraphy. Without these data, scientific ocean drilling, the ultimate ground truth for Marine Geology, cannot be done. The technology and expertise to collect MCS must be adapted for the particular circumstances of the Arctic Ocean. While MCS data have been collected in the Arctic Ocean, the procedures have relied on icebreakers towing equipment. Since icebreakers follow the path of least resistance through the pack, data are acquired in locations that are not scientifically optimal and rarely in the relatively straight lines necessary for optimal processing. Towing in the ice pack is also difficult, inefficient and puts this equipment at substantial risk of crushing or loss. While icebreakers are one means to collect these data, it is time to conduct a systematic evaluation of the costs and benefits of different platforms for MCS data acquisition. This evaluation should enable collection of high-quality data set at selected locations to solve scientific problems. Substantial uncertainties exist about the relative capabilities, costs and limitations for acquisition of MCS data from various platforms in the Arctic Ocean. For example; - Is it possible to collect multi-channel seismic

  18. Statistical Characterisation of the Maximum Eigenvalue of a Wishart Distribution with Application to Multi-Channel SAR System

    NASA Astrophysics Data System (ADS)

    Erten, E.; Zandoná-Schneider, R.; Reigber, A.

    2009-04-01

    Multi-channel SAR system characterise the target with multicomponent Gaussian circular vector whose number of components m is equal to the number of polarimetric and/or interferometric channels of the system. In the case of the multivariate (multi-channel) Gaussian system, the second order statistics known as covariance matrix contains all the necessary information to characterise the target vector. In this framework, the eigendecomposition of the covariance matrix have demonstrated as a important analysis in the physical parameter estimation and target detection. Especially, the maximum eigenvalue related to the first eigenvector of the covariance matrix is the most interesting parameter in a wide selection of application, i.e. polarimetry, GMTI (ground moving target indication) and interferometric phase filtering. Related to this, the cornerstone study considering the statistical description of the covariance matrix eigendecomposition in polarimetry has been carried out in [1]. However, the majority of the analysis in [1] was performed on the basis of numerical methods. In this paper we support the results of [1] by addressing analytical solutions. Specifically, we derive new exact closed form expressions for Probability Density Function (PDF), for Cumulative Dis tribution Function (CDF) and for the Moment Generating Function (MGF) of the multi channel SAR system covariance matrix maximum eigenvalue, thus enabling the exact evaluation of the performance analysis of the estimation and the detection problem considering the number of averaged samples and different correlation scenario. Our results are analysed by means of simulated data.

  19. Hyperbolic Positioning with Antenna Arrays and Multi-Channel Pseudolite for Indoor Localization

    PubMed Central

    Fujii, Kenjirou; Sakamoto, Yoshihiro; Wang, Wei; Arie, Hiroaki; Schmitz, Alexander; Sugano, Shigeki

    2015-01-01

    A hyperbolic positioning method with antenna arrays consisting of proximately-located antennas and a multi-channel pseudolite is proposed in order to overcome the problems of indoor positioning with conventional pseudolites (ground-based GPS transmitters). A two-dimensional positioning experiment using actual devices is conducted. The experimental result shows that the positioning accuracy varies centimeter- to meter-level according to the geometric relation between the pseudolite antennas and the receiver. It also shows that the bias error of the carrier-phase difference observables is more serious than their random error. Based on the size of the bias error of carrier-phase difference that is inverse-calculated from the experimental result, three-dimensional positioning performance is evaluated by computer simulation. In addition, in the three-dimensional positioning scenario, an initial value convergence analysis of the non-linear least squares is conducted. Its result shows that initial values that can converge to a right position exist at least under the proposed antenna setup. The simulated values and evaluation methods introduced in this work can be applied to various antenna setups; therefore, by using them, positioning performance can be predicted in advance of installing an actual system. PMID:26437405

  20. Audio representations of multi-channel EEG: a new tool for diagnosis of brain disorders

    PubMed Central

    Vialatte, François B; Dauwels, Justin; Musha, Toshimitsu; Cichocki, Andrzej

    2012-01-01

    Objective: The objective of this paper is to develop audio representations of electroencephalographic (EEG) multichannel signals, useful for medical practitioners and neuroscientists. The fundamental question explored in this paper is whether clinically valuable information contained in the EEG, not available from the conventional graphical EEG representation, might become apparent through audio representations. Methods and Materials: Music scores are generated from sparse time-frequency maps of EEG signals. Specifically, EEG signals of patients with mild cognitive impairment (MCI) and (healthy) control subjects are considered. Statistical differences in the audio representations of MCI patients and control subjects are assessed through mathematical complexity indexes as well as a perception test; in the latter, participants try to distinguish between audio sequences from MCI patients and control subjects. Results: Several characteristics of the audio sequences, including sample entropy, number of notes, and synchrony, are significantly different in MCI patients and control subjects (Mann-Whitney p < 0.01). Moreover, the participants of the perception test were able to accurately classify the audio sequences (89% correctly classified). Conclusions: The proposed audio representation of multi-channel EEG signals helps to understand the complex structure of EEG. Promising results were obtained on a clinical EEG data set. PMID:23383399

  1. Signal acquisition module design for multi-channel surface magnetic resonance sounding system

    NASA Astrophysics Data System (ADS)

    Lin, Tingting; Chen, Wuqiang; Du, Wenyuan; Zhao, Jing

    2015-11-01

    To obtain a precise 2D/3D image of fissure or karst water, multi-channel magnetic resonance sounding (MRS) systems using edge-to-edge or overlapping receiving coils are needed. Thus, acquiring a nano-volt signal for a small amount of the aquifer and suppressing the mutual coupling between adjacent coils are two important issues for the design of the signal acquisition module in the system. In the present study, we propose to use a passive low pass filter, consisted of a resistance (R) and capacitance (C), to inhibit the mutual coupling effects of the coils. Four low-noise operational amplifiers LT1028, OPA124, AD745, and OP27 were compared with respect to achieving the lowest system noise. As a result, 3 pieces of LT1028 were chosen and connected in parallel to serve as preamplifier, with a sensitivity of 1.4 nV/√Hz at 2 kHz. Experimental results are presented for 2D MRS groundwater investigations conducted in the suburb of Changchun, China. The inversion result is consistent with the result of drilling log, suggesting that the signal acquisition module is well developed.

  2. Image reconstruction of multi-channel photoacoustic and laser-ultrasound data using reverse time migration

    NASA Astrophysics Data System (ADS)

    Johnson, Jami L.; Shragge, Jeffrey; van Wijk, Kasper

    2015-03-01

    We propose a new reconstruction algorithm for photoacoustic and laser-ultrasound imaging based on reverse time migration (RTM), a time reversal imaging algorithm originally developed for exploration seismology. RTM inherently handles strong velocity heterogeneity and complex propagation paths. A successful RTM analysis with appropriate handling of boundary conditions results in enhanced signal-to-noise, accurately located structures, and minimal artifacts. A laser-ultrasound experiment begins with a source wave field generated at the surface that propagates through the sample. Acoustic scatterers in the propagation path give rise to a scattered wave field, which travels to the surface and is recorded by acoustic detectors. To reconstruct the laser-ultrasound image, a synthetic source function is forward propagated and cross-correlated with the time-reversed and back-propagated recorded (scattered) wave field to image the scatterers at the correct location. Conversely, photoacoustic waves are generated by chromophores within the sample and propagate "one-way" to the detection surface. We utilize the velocity model validated by the laser-ultrasound reconstruction to accurately reconstruct the photoacoustic image with RTM. This approach is first validated with simulations, where inclusions behave both as a photoacoustic source and an acoustic scatterer. Subsequently, we demonstrate the capabilities of RTM with tissue phantom experiments using an all-optical, multi-channel acquisition geometry.

  3. Multi-channel monolithic integrated optic fiber Bragg grating sensor interrogator

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Zongjian

    2011-09-01

    Fiber Bragg grating (FBG) is a mature sensing technology for the measurement of strain, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion. It has gained rapid acceptance in civil, aerospace, chemical and petrochemical, medicine, aviation and automotive industries. The most prominent advantages of FBG are: small size and light weight, distributed array of FBG transducers on a single fiber, and immunity to radio frequency interference. However, a major disadvantage of FBG technology is that conventional state-of-the-art FBG interrogation system is typically bulky, heavy, and costly bench top instruments that are typically assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the industrial need for a compact FBG interrogation system, this paper describes recent progress towards the development of miniature fiber Bragg grating sensor interrogator (FBG-Transceiver™) system based on multi-channel monolithic integrated optic sensor microchip technology. The integrated optic microchip technology enables monolithic integration of all functionalities, both passive and active, of conventional bench top FBG sensor interrogator system, packaged in a miniaturized, low power operation, 2 cm×5 cm small form factor (SFF) package suitable for long-term structural health monitoring in applications where size, weight, and power are critical for operation.

  4. Long-Term Drought Forecasting based on Climate Signals using Multi-Channel

    NASA Astrophysics Data System (ADS)

    Cui, H.; Singh, V. P.; Tang, Q.; Ge, Q.

    2015-12-01

    Drought is an insidious natural hazard, which may cause severe damage both in natural environment and human society. Timely drought forecasting enables civil protection authorities and public to take actions to reduce the risk of droughts. Thus drought forecasting plays an important role in setting out drought mitigation strategy. Analysis of the dominant oscillations of droughts and large-scale climate indices has shown that climate indices, such as the El Niño Southern Oscillation (ENSO), are significant indicators of drought occurrences in southern United States. It suggests that the climate indices may be used in drought forecasting at a long lead time. In this study, the multi-channel entropy spectral analysis (MCESA) was developed to incorporate the ENSO climate signals to entropy approach for long-term drought forecasting. To focus on the lack of surface water, drought was quantified by standardized streamflow index (SSI) in this study. SSI time series turned out to be stationary and highly autocorrelated, which showed significant 12-month periodicity. As a result, SSI was successfully forecasted using MCESA with ENSO as an indicator for lead times of 4-6 years. The drought forecasting was more reliable for the stations in humid areas than arid areas. Comparison from the retrospective drought forecasts with or without ENSO showed that inclusion of ENSO climate signals reduced the forecasting errors. The forecasts under El Nino (La Nina) condition reduced (increased) drought severity, making the forecasts more accurate.

  5. A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells.

    PubMed

    Calderón, Antonio José; González, Isaías; Calderón, Manuel; Segura, Francisca; Andújar, José Manuel

    2016-01-01

    In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level. PMID:27005630

  6. A multi-channel biomimetic neuroprosthesis to support treadmill gait training in stroke patients.

    PubMed

    Chia, Noelia; Ambrosini, Emilia; Baccinelli, Walter; Nardone, Antonio; Monticone, Marco; Ferrigno, Giancarlo; Pedrocchi, Alessandra; Ferrante, Simona

    2015-08-01

    This study presents an innovative multi-channel neuroprosthesis that induces a biomimetic activation of the main lower-limb muscles during treadmill gait training to be used in the rehabilitation of stroke patients. The electrostimulation strategy replicates the physiological muscle synergies used by healthy subjects to walk on a treadmill at their self-selected speed. This strategy is mapped to the current gait sub-phases, which are identified in real time by a custom algorithm. This algorithm divides the gait cycle into six sub-phases, based on two inertial sensors placed laterally on the shanks. Therefore, the pre-defined stimulation profiles are expanded or stretched based on the actual gait pattern of each single subject. A preliminary experimental protocol, involving 10 healthy volunteers, was carried out to extract the muscle synergies and validate the gait-detection algorithm, which were afterwards used in the development of the neuroprosthesis. The feasibility of the neuroprosthesis was tested on one healthy subject who simulated different gait patterns, and a chronic stroke patient. The results showed the correct functioning of the system. A pilot study of the neurorehabilitation treatment for stroke patients is currently being carried out. PMID:26737943

  7. A Multi-Channel, Flex-Rigid ECoG Microelectrode Array for Visual Cortical Interfacing

    PubMed Central

    Tolstosheeva, Elena; Gordillo-González, Víctor; Biefeld, Volker; Kempen, Ludger; Mandon, Sunita; Kreiter, Andreas K.; Lang, Walter

    2015-01-01

    High-density electrocortical (ECoG) microelectrode arrays are promising signal-acquisition platforms for brain-computer interfaces envisioned, e.g., as high-performance communication solutions for paralyzed persons. We propose a multi-channel microelectrode array capable of recording ECoG field potentials with high spatial resolution. The proposed array is of a 150 mm2 total recording area; it has 124 circular electrodes (100, 300 and 500 μm in diameter) situated on the edges of concentric hexagons (min. 0.8 mm interdistance) and a skull-facing reference electrode (2.5 mm2 surface area). The array is processed as a free-standing device to enable monolithic integration of a rigid interposer, designed for soldering of fine-pitch SMD-connectors on a minimal assembly area. Electrochemical characterization revealed distinct impedance spectral bands for the 100, 300 and 500 μm-type electrodes, and for the array's own reference. Epidural recordings from the primary visual cortex (V1) of an awake Rhesus macaque showed natural electrophysiological signals and clear responses to standard visual stimulation. The ECoG electrodes of larger surface area recorded signals with greater spectral power in the gamma band, while the skull-facing reference electrode provided higher average gamma power spectral density (γPSD) than the common average referencing technique. PMID:25569757

  8. A compact multi-channel fluorescence sensor with ambient light suppression

    NASA Astrophysics Data System (ADS)

    Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

    2012-03-01

    A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

  9. A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells

    PubMed Central

    Calderón, Antonio José; González, Isaías; Calderón, Manuel; Segura, Francisca; Andújar, José Manuel

    2016-01-01

    In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level. PMID:27005630

  10. Signal acquisition module design for multi-channel surface magnetic resonance sounding system.

    PubMed

    Lin, Tingting; Chen, Wuqiang; Du, Wenyuan; Zhao, Jing

    2015-11-01

    To obtain a precise 2D/3D image of fissure or karst water, multi-channel magnetic resonance sounding (MRS) systems using edge-to-edge or overlapping receiving coils are needed. Thus, acquiring a nano-volt signal for a small amount of the aquifer and suppressing the mutual coupling between adjacent coils are two important issues for the design of the signal acquisition module in the system. In the present study, we propose to use a passive low pass filter, consisted of a resistance (R) and capacitance (C), to inhibit the mutual coupling effects of the coils. Four low-noise operational amplifiers LT1028, OPA124, AD745, and OP27 were compared with respect to achieving the lowest system noise. As a result, 3 pieces of LT1028 were chosen and connected in parallel to serve as preamplifier, with a sensitivity of 1.4 nV/√Hz at 2 kHz. Experimental results are presented for 2D MRS groundwater investigations conducted in the suburb of Changchun, China. The inversion result is consistent with the result of drilling log, suggesting that the signal acquisition module is well developed. PMID:26628154

  11. Automated Interval velocity picking for Atlantic Multi-Channel Seismic Data

    NASA Astrophysics Data System (ADS)

    Singh, Vishwajit

    2016-04-01

    This paper described the challenge in developing and testing a fully automated routine for measuring interval velocities from multi-channel seismic data. Various approaches are employed for generating an interactive algorithm picking interval velocity for continuous 1000-5000 normal moveout (NMO) corrected gather and replacing the interpreter's effort for manual picking the coherent reflections. The detailed steps and pitfalls for picking the interval velocities from seismic reflection time measurements are describe in these approaches. Key ingredients these approaches utilized for velocity analysis stage are semblance grid and starting model of interval velocity. Basin-Hopping optimization is employed for convergence of the misfit function toward local minima. SLiding-Overlapping Window (SLOW) algorithm are designed to mitigate the non-linearity and ill- possessedness of root-mean-square velocity. Synthetic data case studies addresses the performance of the velocity picker generating models perfectly fitting the semblance peaks. A similar linear relationship between average depth and reflection time for synthetic model and estimated models proposed picked interval velocities as the starting model for the full waveform inversion to project more accurate velocity structure of the subsurface. The challenges can be categorized as (1) building accurate starting model for projecting more accurate velocity structure of the subsurface, (2) improving the computational cost of algorithm by pre-calculating semblance grid to make auto picking more feasible.

  12. A multi-channel telemetry system for brain microstimulation in freely roaming animals.

    PubMed

    Xu, Shaohua; Talwar, Sanjiv K; Hawley, Emerson S; Li, Lei; Chapin, John K

    2004-02-15

    A system is described that enables an experimenter to remotely deliver electrical pulse train stimuli to multiple different locations in the brains of freely moving rats. The system consists of two separate components: a transmitter base station that is controlled by a PC operator, and a receiver-microprocessor integrated pack worn on the back of the animals and which connects to suitably implanted brain locations. The backpack is small and light so that small animal subjects can easily carry it. Under remote command from the PC the backpack can be configured to provide biphasic pulse trains of arbitrarily specified parameters. A feature of the system is that it generates precise brain-stimulation behavioral effects using the direct constant-voltage TTL output of the backpack microprocessor. The system performs with high fidelity even in complex environments over a distance of about 300 m. Rat self-stimulation tests showed that this system produced the same behavioral responses as a conventional constant-current stimulator. This system enables a variety of multi-channel brain stimulation experiments in freely moving animals. We have employed it to develop a new animal behavior model ("virtual" conditioning) for the neurophysiological study of spatial learning, in which a rat can be accurately guided to navigate various terrains. PMID:14757345

  13. Monitoring of ion implantation in microelectronics production environment using multi-channel reflectometry

    NASA Astrophysics Data System (ADS)

    Ebersbach, Peter; Urbanowicz, Adam M.; Likhachev, Dmitry; Hartig, Carsten

    2016-03-01

    Optical metrology techniques such as ellipsometry and reflectometry are very powerful for routine process monitoring and control in the modern semiconductor manufacturing industry. However, both methods rely on optical modeling therefore, the optical properties of all materials in the stack need to be characterized a priori or determined during characterization. Some processes such as ion implantation and subsequent annealing produce slight variations in material properties within wafer, wafer-to-wafer, and lot-to-lot; such variation can degrade the dimensional measurement accuracy for both unpatterned optical measurements as well as patterned (2D and 3D) scatterometry measurements. These variations can be accounted for if the optical model of the structure under investigation allows one to extract not just dimensional but also material information already residing within the optical spectra. This paper focuses on modeling of ion implanted and annealed poly Si stacks typically used in high-k technology. Monitoring of ion implantation is often a blind spot in mass production due to capability issues and other limitations of common methods. Typically, the ion implantation dose can be controlled by research-grade ellipsometers with extended infrared range. We demonstrate that multi-channel spectroscopic reflectometry can also be used for ion implant monitoring in the mass-production environment. Our findings are applicable across all technology nodes.

  14. Portable e-Tongue based on Multi-channel LAPS Array with PVC Membrane for Rapid Environment Detection

    NASA Astrophysics Data System (ADS)

    Ha, D.; Yu, H.; Hu, N.; Wu, C. X.; Zhou, J.; Kirsanov, Dmitry; Legin, Andrey; Wang, P.

    2011-09-01

    A new kind of portable e-Tongue based on multi-channel LAPS array with PVC membrane has been designed for the rapid detection of environment situation, especially the seawater. It has the great advantages of depositing membranes which are offered by Chemistry Department, Saint-Petersburg State University on the sensors artificially with convenience and efficiency. To detect various heavy metal ions (Pb2+, Cd2+, Zn2+) simultaneously, respective Polyvinyl Chloride (PVC) membrane could be prepared on the surface of the silicon-based sensor in different channel.

  15. Simultaneous retrieval of total ozone column amounts and cloud/aerosol optical depths from multi-channel, moderate bandwidth filter instruments

    NASA Astrophysics Data System (ADS)

    Stamnes, Knut; Fan, Lingling; Li, Wei; Dahlback, Arne; Stamnes, Jakob; Stamnes, Snorre

    2015-04-01

    A new method is presented based on using neural networks (NN) to analyze ultraviolet (UV) irradiance data recorded by multi-channel, moderate bandwidth filter instruments. Application of the NN method to three years of data obtained by a NILU-UV multi-channel, moderate bandwidth filter instrument, revealed that compared to a traditional look-up table (LUT) method, the NN method yielded better agreement against the Ozone Monitoring Instrument (OMI) with a 1% decrease in relative difference and a significant increase in the correlation of total ozone column (TOC) values. Furthermore, this new method resulted in larger number of valid retrievals (daily average values within a meaningful range of 200-500 DU) than the LUT method. Compared with NN retrievals based on NILU-UV irradiance measurements, TOC values obtained from OMI were underestimated under cloudy conditions. Cloud optical depth (COD) values derived by the NN method were more reliable than corresponding results derived by the LUT method, the latter results were less accurate for heavy cloud cover, broken cloud situations or snow-covered ground. The potential for retrieving aerosol optical depth (AOD) values under cloud-free conditions will be discussed. The cloud-aerosol information obtained by irradiance instruments such as the NILU-UV can be used in conjunction with a radiative transfer model to estimate cloud/aerosol radiative forcing and hence the impact of clouds and aerosols on the radiative energy balance. Deployment of multi-channel, moderate bandwidth filter instruments at AERONET sites and analysis of such data in conjunction with AERONET and satellite remote sensing data can provide crucial information needed for the assessment of the influence of ozone, clouds, and aerosols on climate.

  16. Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03693 Channel

    This channel is located south of Iani Chaos.

    Image information: VIS instrument. Latitude -10.9N, Longitude 345.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. Design Study of a Multi-channel Array Particle Spectrometer for Space Missions

    NASA Astrophysics Data System (ADS)

    Trindade, Andreia; Assis, P.; Brogueira, P.; Gonçalves, P.; Keating, A.; Pimenta, M.; Rodrigues, P.; Trindade, A.

    In this work, a novel particle spectrometer is proposed to fulfil the need to map the space radiation environment for future space missions and to provide more accurate scientific data. The concept of the instrument brings together new radiation-hard technologies, for the photo-sensors and scintillating materials that will improve the quality of the data, while taking into account the limited resources such as mass, power and accommodation, allocated for space radiation monitors. The Multi-channel Array Particle Spectrometer (MAPS), can measure fluxes and energy dis-tributions of protons, ions, electrons and gammas in a wide energy range based on the 3D reconstruction of the particle track through the detector and its deposited energy in the active volume. It consists on a 8 x 8 segmented scintillator block built from 3.2 x 3.2 x 20 mm3 indi-vidual LYSO:Ce rods that are readout at both ends by two 64 pixel Silicon Photo-Multipliers (SiPMs) matrices, a new generation of high gain (105-106) avalanche photodiodes working in controlled Geiger mode, that collect the scintillating light produced by the interactions of the charged particles in the crystals. Each SiPM matrix is readout by a 64 channel mixed sig-nal analog-digital ASIC, offering both particle identification and particle counting capabilities. Power cycling design of the ASIC allows to activate the particle identification block only during a pre-determined time slice, keeping the total power budget of less than 1 mW/channel. An on-board FPGA sorts the serialized data from the two ASICs and computes the trigger primitives in real-time and in an event-by-event basis. Whenever a charged particle crosses the segmented volume of the detector, the XY coordinates, given by the pixelized crystal positions, and the deposited energy in each crystal is recorded. The double readout scheme allows to compute the light collection asymmetry between both ends of the crystal and to use that information to record the

  18. A primary analysis of microwave brightness temperature of lunar surface from Chang-E 1 multi-channel radiometer observation and inversion of regolith layer thickness

    NASA Astrophysics Data System (ADS)

    Fa, Wenzhe; Jin, Ya-Qiu

    2010-06-01

    In China's first lunar exploration project, Chang-E 1 (CE-1), a multi-channel microwave radiometer was aboard the satellite, with the purpose of measuring microwave brightness temperature (Tb) from lunar surface and surveying the global distribution of lunar regolith layer thickness. In this paper, the primary 621 tracks of swath data measured by CE-1 microwave radiometer from November 2007 to February 2008 are collected and analyzed. Using the nearest neighbor interpolation to collect the Tb data under the same Sun illumination, global distributions of microwave brightness temperature from lunar surface at lunar daytime and nighttime are constructed. Based on the three-layer media modeling (the top dust-soil, regolith and underlying rock media) for microwave thermal emission of lunar surface, the CE-1 measured Tb and its dependence upon latitude, frequency and FeO + TiO 2 content, etc. are discussed. The CE-1 Tb data at Apollo landing sites are especially chosen for validation and calibration on the basis of available ground measurements. Using the empirical dependence of physical temperature upon the latitude verified by the CE-1 multi-channel Tb data at Apollo landing sites, the global distribution of regolith layer thickness is further inverted from the CE-1 brightness temperature data at 3 GHz channel. Those inversions at Apollo landing sites and the characteristics of regolith layer thickness for lunar maria are well compared with the Apollo in situ measurements and the regolith thickness derived from the Earth-based radar data. Finally, the statistical distribution of regolith thickness is analyzed and discussed.

  19. Multi-stage perturbation theory for compensating intra-channel nonlinear impairments in fiber-optic links.

    PubMed

    Liang, Xiaojun; Kumar, Shiva

    2014-12-01

    A recursive perturbation theory to model the fiber-optic system is developed. Using this perturbation theory, a multi-stage compensation technique to mitigate the intra-channel nonlinear impairments is investigated. The technique is validated by numerical simulations of a single-polarization single-channel fiber-optic system operating at 28 Gbaud, 32-quadrature amplitude modulation (32-QAM), and 40 × 80 km transmission distance. It is found that, with 2 samples per symbol, the multi-stage scheme with eight compensation stages increases the Q-factor as compared with linear compensation by 4.5 dB; as compared with single-stage compensation, the computational complexity is reduced by a factor of 1.3 and the required memory for storing perturbation coefficients is decreased by a factor of 13. PMID:25606904

  20. Implementation of a galvanically isolated low-noise power supply board for multi-channel headstage preamplifiers.

    PubMed

    Tóth, Attila; Máthé, Kálmán; Petykó, Zoltán; Szabó, Imre; Czurkó, András

    2008-06-15

    Custom made multi-channel headstage preamplifiers are traditionally powered by battery. By the use of an isolated unregulated DC/DC converter integrated circuit (DCP010512B from Texas Instruments Inc., TX, USA), here we describe the implementation of a galvanically isolated low-noise power supply board for multi-channel headstage preamplifiers. The implemented galvanically isolated power supply board provides the same quality noise free recording as the battery power supply. The non-isolated part of the power supply board is powered by standard 230 V AC/6 V DC wall mount adapter or USB cable. The described galvanically isolated power supply board can replace the batteries in preamplifier power supplies without any deterioration of the quality of recordings. PMID:18372046

  1. Generation and detection of broadband multi-channel orbital angular momentum by micrometer-scale meta-reflectarray.

    PubMed

    Liu, Jinpeng; Min, Changjun; Lei, Ting; Du, Luping; Yuan, Yangsheng; Wei, Shibiao; Wang, Yiping; Yuan, X-C

    2016-01-11

    We theoretically demonstrate the generation and detection of broadband multi-channel Orbital Angular Momentum(OAM) by a micrometer-scale meta-reflectarray. The meta-reflectarray composed of patterned silicon bars on a silver ground plane can be designed to realize phase modulation and work as chip-level OAM devices. Compared to traditional methods of OAM generation and detection, our approach shows superiorities of very compact structure size, broadband working wavelength (1250-1750 nm), high diffraction efficiency (~70%), simultaneously handling multiplex OAMs, and tunable reflection angle (0-45°). These fascinating advantages provides great potential applications in photonic integrated devices and systems for high-capacity and multi-channel OAM communication. PMID:26832252

  2. Equalization enhanced phase noise in Nyquist-spaced superchannel transmission systems using multi-channel digital back-propagation

    NASA Astrophysics Data System (ADS)

    Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C.; Savory, Seb J.; Killey, Robert I.; Bayvel, Polina

    2015-09-01

    Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems.

  3. Equalization enhanced phase noise in Nyquist-spaced superchannel transmission systems using multi-channel digital back-propagation

    PubMed Central

    Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C.; Savory, Seb J.; Killey, Robert I.; Bayvel, Polina

    2015-01-01

    Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems. PMID:26365422

  4. Multi-channel programmable power supply with temperature compensation for silicon sensors

    NASA Astrophysics Data System (ADS)

    Shukla, R. A.; Achanta, V. G.; Dugad, S. R.; Freeman, J.; Garde, C. S.; Gupta, S. K.; Khandekar, P. D.; Kurup, A. M.; Lokhandwala, S. S.; Los, S.; Prabhu, S. S.; Rakshe, P. S.

    2016-01-01

    Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu et al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al., Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this article. The

  5. Multi-channel programmable power supply with temperature compensation for silicon sensors.

    PubMed

    Shukla, R A; Achanta, V G; Dugad, S R; Freeman, J; Garde, C S; Gupta, S K; Khandekar, P D; Kurup, A M; Lokhandwala, S S; Los, S; Prabhu, S S; Rakshe, P S

    2016-01-01

    Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu et al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al., Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this

  6. Strategic Positioning of the Web in a Multi-Channel Market Approach.

    ERIC Educational Resources Information Center

    Simons, Luuk P. A.; Steinfield, Charles; Bouwman, Harry

    2002-01-01

    Discusses channel economics in retail activities and trends toward unbundling due to the emergence of the Web channel. Highlights include sales processes and physical distribution processes; transaction costs; hybrid electronic commerce strategies; channel management and customer support; information economics, thing economics, and service…

  7. Nonlocal atlas-guided multi-channel forest learning for human brain labeling

    PubMed Central

    Ma, Guangkai; Gao, Yaozong; Wu, Guorong; Wu, Ligang; Shen, Dinggang

    2016-01-01

    Purpose: It is important for many quantitative brain studies to label meaningful anatomical regions in MR brain images. However, due to high complexity of brain structures and ambiguous boundaries between different anatomical regions, the anatomical labeling of MR brain images is still quite a challenging task. In many existing label fusion methods, appearance information is widely used. However, since local anatomy in the human brain is often complex, the appearance information alone is limited in characterizing each image point, especially for identifying the same anatomical structure across different subjects. Recent progress in computer vision suggests that the context features can be very useful in identifying an object from a complex scene. In light of this, the authors propose a novel learning-based label fusion method by using both low-level appearance features (computed from the target image) and high-level context features (computed from warped atlases or tentative labeling maps of the target image). Methods: In particular, the authors employ a multi-channel random forest to learn the nonlinear relationship between these hybrid features and target labels (i.e., corresponding to certain anatomical structures). Specifically, at each of the iterations, the random forest will output tentative labeling maps of the target image, from which the authors compute spatial label context features and then use in combination with original appearance features of the target image to refine the labeling. Moreover, to accommodate the high inter-subject variations, the authors further extend their learning-based label fusion to a multi-atlas scenario, i.e., they train a random forest for each atlas and then obtain the final labeling result according to the consensus of results from all atlases. Results: The authors have comprehensively evaluated their method on both public LONI_LBPA40 and IXI datasets. To quantitatively evaluate the labeling accuracy, the authors use the

  8. The dynamic time-over-threshold method for multi-channel APD based gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Orita, T.; Shimazoe, K.; Takahashi, H.

    2015-03-01

    t- Recent advances in manufacturing technology have enabled the use of multi-channel pixelated detectors in gamma-ray imaging applications. When obtaining gamma-ray measurements, it is important to obtain pulse height information in order to avoid unnecessary events such as scattering. However, as the number of channels increases, more electronics are needed to process each channel's signal, and the corresponding increases in circuit size and power consumption can result in practical problems. The time-over-threshold (ToT) method, which has recently become popular in the medical field, is a signal processing technique that can effectively avoid such problems. However, ToT suffers from poor linearity and its dynamic range is limited. We therefore propose a new ToT technique called the dynamic time-over-threshold (dToT) method [4]. A new signal processing system using dToT and CR-RC shaping demonstrated much better linearity than that of a conventional ToT. Using a test circuit with a new Gd3Al2Ga3O12 (GAGG) scintillator and an avalanche photodiode, the pulse height spectra of 137Cs and 22Na sources were measured with high linearity. Based on these results, we designed a new application-specific integrated circuit (ASIC) for this multi-channel dToT system, measured the spectra of a 22Na source, and investigated the linearity of the system.

  9. Multi-channel transport experiments at Alcator C-Mod and comparison with gyrokinetic simulationsa)

    NASA Astrophysics Data System (ADS)

    White, A. E.; Howard, N. T.; Greenwald, M.; Reinke, M. L.; Sung, C.; Baek, S.; Barnes, M.; Candy, J.; Dominguez, A.; Ernst, D.; Gao, C.; Hubbard, A. E.; Hughes, J. W.; Lin, Y.; Mikkelsen, D.; Parra, F.; Porkolab, M.; Rice, J. E.; Walk, J.; Wukitch, S. J.; Team, Alcator C-Mod

    2013-05-01

    Multi-channel transport experiments have been conducted in auxiliary heated (Ion Cyclotron Range of Frequencies) L-mode plasmas at Alcator C-Mod [Marmar and Alcator C-Mod Group, Fusion Sci. Technol. 51(3), 3261 (2007)]. These plasmas provide good diagnostic coverage for measurements of kinetic profiles, impurity transport, and turbulence (electron temperature and density fluctuations). In the experiments, a steady sawtoothing L-mode plasma with 1.2 MW of on-axis RF heating is established and density is scanned by 20%. Measured rotation profiles change from peaked to hollow in shape as density is increased, but electron density and impurity profiles remain peaked. Ion or electron heat fluxes from the two plasmas are the same. The experimental results are compared directly to nonlinear gyrokinetic theory using synthetic diagnostics and the code GYRO [Candy and Waltz, J. Comput. Phys. 186, 545 (2003)]. We find good agreement with experimental ion heat flux, impurity particle transport, and trends in the fluctuation level ratio (T˜e/Te)/(n ˜e/ne), but underprediction of electron heat flux. We find that changes in momentum transport (rotation profiles changing from peaked to hollow) do not correlate with changes in particle transport, and also do not correlate with changes in linear mode dominance, e.g., Ion Temperature Gradient versus Trapped Electron Mode. The new C-Mod results suggest that the drives for momentum transport differ from drives for heat and particle transport. The experimental results are inconsistent with present quasilinear models, and the strong sensitivity of core rotation to density remains unexplained.

  10. Multi-channel transport experiments at Alcator C-Mod and comparison with gyrokinetic simulations

    SciTech Connect

    White, A. E.; Howard, N. T.; Greenwald, M.; Reinke, M. L.; Sung, C.; Baek, S.; Barnes, M.; Dominguez, A.; Ernst, D.; Gao, C.; Hubbard, A. E.; Hughes, J. W.; Lin, Y.; Parra, F.; Porkolab, M.; Rice, J. E.; Walk, J.; Wukitch, S. J.; Team, Alcator C-Mod; Candy, J.; and others

    2013-05-15

    Multi-channel transport experiments have been conducted in auxiliary heated (Ion Cyclotron Range of Frequencies) L-mode plasmas at Alcator C-Mod [Marmar and Alcator C-Mod Group, Fusion Sci. Technol. 51(3), 3261 (2007)]. These plasmas provide good diagnostic coverage for measurements of kinetic profiles, impurity transport, and turbulence (electron temperature and density fluctuations). In the experiments, a steady sawtoothing L-mode plasma with 1.2 MW of on-axis RF heating is established and density is scanned by 20%. Measured rotation profiles change from peaked to hollow in shape as density is increased, but electron density and impurity profiles remain peaked. Ion or electron heat fluxes from the two plasmas are the same. The experimental results are compared directly to nonlinear gyrokinetic theory using synthetic diagnostics and the code GYRO [Candy and Waltz, J. Comput. Phys. 186, 545 (2003)]. We find good agreement with experimental ion heat flux, impurity particle transport, and trends in the fluctuation level ratio (T(tilde sign){sub e}/T{sub e})/(ñ{sub e}/n{sub e}), but underprediction of electron heat flux. We find that changes in momentum transport (rotation profiles changing from peaked to hollow) do not correlate with changes in particle transport, and also do not correlate with changes in linear mode dominance, e.g., Ion Temperature Gradient versus Trapped Electron Mode. The new C-Mod results suggest that the drives for momentum transport differ from drives for heat and particle transport. The experimental results are inconsistent with present quasilinear models, and the strong sensitivity of core rotation to density remains unexplained.

  11. A Novel GBM Saliency Detection Model Using Multi-Channel MRI

    PubMed Central

    Banerjee, Subhashis; Mitra, Sushmita; Shankar, B. Uma; Hayashi, Yoichi

    2016-01-01

    The automatic computerized detection of regions of interest (ROI) is an important step in the process of medical image processing and analysis. The reasons are many, and include an increasing amount of available medical imaging data, existence of inter-observer and inter-scanner variability, and to improve the accuracy in automatic detection in order to assist doctors in diagnosing faster and on time. A novel algorithm, based on visual saliency, is developed here for the identification of tumor regions from MR images of the brain. The GBM saliency detection model is designed by taking cue from the concept of visual saliency in natural scenes. A visually salient region is typically rare in an image, and contains highly discriminating information, with attention getting immediately focused upon it. Although color is typically considered as the most important feature in a bottom-up saliency detection model, we circumvent this issue in the inherently gray scale MR framework. We develop a novel pseudo-coloring scheme, based on the three MRI sequences, viz. FLAIR, T2 and T1C (contrast enhanced with Gadolinium). A bottom-up strategy, based on a new pseudo-color distance and spatial distance between image patches, is defined for highlighting the salient regions in the image. This multi-channel representation of the image and saliency detection model help in automatically and quickly isolating the tumor region, for subsequent delineation, as is necessary in medical diagnosis. The effectiveness of the proposed model is evaluated on MRI of 80 subjects from the BRATS database in terms of the saliency map values. Using ground truth of the tumor regions for both high- and low- grade gliomas, the results are compared with four highly referred saliency detection models from literature. In all cases the AUC scores from the ROC analysis are found to be more than 0.999 ± 0.001 over different tumor grades, sizes and positions. PMID:26752735

  12. Multi-Channel Seismic Images of the Mariana Forearc: EW0202 Initial Results

    NASA Astrophysics Data System (ADS)

    Oakley, A. J.; Goodliffe, A. M.; Taylor, B.; Moore, G. F.; Fryer, P.

    2002-12-01

    During the Spring of 2002, the Mariana Subduction Factory was surveyed using multi-channel seismics (MCS) as the first major phase of a US-Japanese collaborative NSF-MARGINS funded project. The resulting geophysical transects extend from the Pacific Plate to the West Mariana remnant arc. For details of this survey, including the results from the back-arc, refer to Taylor et al. (this session). The incoming Pacific Plate and its accompanying seamounts are deformed by plate flexure, resulting in extension of the upper crust as it enters the subduction zone. The resultant trench parallel faults dominate the bathymetry and MCS data. Beneath the forearc, in the southern transects near Saipan, the subducting slab is imaged to a distance of 50-60 km arcward. In addition to ubiquitous trench parallel normal faulting, a N-S transect of the forearc clearly shows normal faults perpendicular to the trench resulting from N-S extension. On the east side of the Mariana Ridge, thick sediment packages extend into the forearc. Directly east of Saipan and Tinian, a large, deeply scouring slide mass is imaged. Several serpentine mud volcanoes (Big Blue, Turquoise and Celestial) were imaged on the Mariana Forearc. Deep horizontal reflectors (likely original forearc crust) are imaged under the flanks of some of these seamounts. A possible "throat" reflector is resolved on multiple profiles at the summit of Big Blue, the northern-most seamount in the study area. The flanks of Turquoise seamount terminate in toe thrusts that represent uplift and rotation of surrounding sediments as the volcano grows outward. These thrusts form a basal ridge around the seamount similar to that previously noted encircling Conical Seamount. Furthermore, MCS data has revealed that some forearc highs previously thought to be fault blocks are in actuality mud volcanoes.

  13. High Speed, Multi-Channel, Thermal Instrument Development in Support of HyspIRI-TIR

    NASA Technical Reports Server (NTRS)

    Johnson, William R.; Hook, Simon J.; Foote, Marc; Eng, Bjorn T.; Jau, Bruno

    2011-01-01

    The Jet Propulsion Laboratory is currently developing an end-to-end instrument which will provide a proof of concept prototype vehicle for a high data rate, multi-channel, thermal instrument in support of the Hyperspectral Infrared Imager (HyspIRI)-Thermal Infrared (TIR) space mission. HyspIRI mission was recommended by the National Research Council Decadal Survey (DS). The HyspIRI mission includes a visible shortwave infrared (SWIR) pushboom spectrometer and a multispectral whiskbroom thermal infrared (TIR) imager. The prototype testbed instrument addressed in this effort will only support the TIR. Data from the HyspIRI mission will be used to address key science questions related to the Solid Earth and Carbon Cycle and Ecosystems focus areas of the NASA Science Mission Directorate. Current designs for the HyspIRI-TIR space borne imager utilize eight spectral bands delineated with filters. The system will have 60m ground resolution, 200mK NEDT, 0.5C absolute temperature resolution with a 5-day repeat from LEO orbit. The prototype instrument will use mercury cadmium telluride (MCT) technology at the focal plane array in time delay integration mode. A custom read out integrated circuit (ROIC) will provide the high speed readout hence high data rates needed for the 5 day repeat. The current HyspIRI requirements dictate a ground knowledge measurement of 30m, so the prototype instrument will tackle this problem with a newly developed interferometeric metrology system. This will provide an absolute measurement of the scanning mirror to an order of magnitude better than conventional optical encoders. This will minimize the reliance on ground control points hence minimizing postprocessing (e.g. geo-rectification computations).

  14. A dynamic multi-channel speech enhancement system for distributed microphones in a car environment

    NASA Astrophysics Data System (ADS)

    Matheja, Timo; Buck, Markus; Fingscheidt, Tim

    2013-12-01

    Supporting multiple active speakers in automotive hands-free or speech dialog applications is an interesting issue not least due to comfort reasons. Therefore, a multi-channel system for enhancement of speech signals captured by distributed distant microphones in a car environment is presented. Each of the potential speakers in the car has a dedicated directional microphone close to his position that captures the corresponding speech signal. The aim of the resulting overall system is twofold: On the one hand, a combination of an arbitrary pre-defined subset of speakers' signals can be performed, e.g., to create an output signal in a hands-free telephone conference call for a far-end communication partner. On the other hand, annoying cross-talk components from interfering sound sources occurring in multiple different mixed output signals are to be eliminated, motivated by the possibility of other hands-free applications being active in parallel. The system includes several signal processing stages. A dedicated signal processing block for interfering speaker cancellation attenuates the cross-talk components of undesired speech. Further signal enhancement comprises the reduction of residual cross-talk and background noise. Subsequently, a dynamic signal combination stage merges the processed single-microphone signals to obtain appropriate mixed signals at the system output that may be passed to applications such as telephony or a speech dialog system. Based on signal power ratios between the particular microphone signals, an appropriate speaker activity detection and therewith a robust control mechanism of the whole system is presented. The proposed system may be dynamically configured and has been evaluated for a car setup with four speakers sitting in the car cabin disturbed in various noise conditions.

  15. PULSE HEIGHT ANALYZER

    DOEpatents

    Johnstone, C.W.

    1958-01-21

    An anticoincidence device is described for a pair of adjacent channels of a multi-channel pulse height analyzer for preventing the lower channel from generating a count pulse in response to an input pulse when the input pulse has sufficient magnitude to reach the upper level channel. The anticoincidence circuit comprises a window amplifier, upper and lower level discriminators, and a biased-off amplifier. The output of the window amplifier is coupled to the inputs of the discriminators, the output of the upper level discriminator is connected to the resistance end of a series R-C network, the output of the lower level discriminator is coupled to the capacitance end of the R-C network, and the grid of the biased-off amplifier is coupled to the junction of the R-C network. In operation each discriminator produces a negative pulse output when the input pulse traverses its voltage setting. As a result of the connections to the R-C network, a trigger pulse will be sent to the biased-off amplifier when the incoming pulse level is sufficient to trigger only the lower level discriminator.

  16. Examination of Single- and Multi-Channel GPR Bridge Deck Condition Assessment Methods with Comparison to Complementary NDE Results

    NASA Astrophysics Data System (ADS)

    Romero, Francisco A.; Manacorda, Guido; Simi, Alessandro; Gucunski, Nenad; Parvardeh, Hooman

    2013-04-01

    A sixteen-channel GPR system which houses both longitudinally- and transversely-polarized, 2.0 GHz antenna elements within a single housing was compared with a single-channel GPR system that was separately using both 1.5GHz and 2.6GHz antennas oriented in the transverse polarization, for the purpose of determining effectiveness of bridge deck condition assessment. The multi-channel system has obvious benefits which include closely-spaced GPR antennas (channels) that provide better lateral resolution, as well as combined data sets from co-linear antennas oriented in both the transverse and longitudinal polarizations, which has benefits for imaging within the deck's internal structure. However, the primary objective was to determine whether the multi-channel system would perform in a similar manner to proven single-channel GPR technology during an attenuation-based GPR condition assessment on an older, partially deteriorated deck in northwestern New Jersey that is annually exposed to freeze-thaw conditions as well as de-icing salts. These assessments were made by focusing on identifying the strongest reflections from the upper mat of transversely-oriented rebars within the deck and comparing reflection strength, or conversely, attenuation of the GPR signal, from each of the 'picked' GPR rebar responses. Coordinates for each of the GPR picks, along with amplitude or attenuation measurements, were gridded and contour-plotted for the purpose of identifying areas identified as either relatively deteriorated or sound. Initially, results were compared for data with no applied correction that takes into account GPR signal attenuation with increasing depth within the concrete deck. Final GPR maps were produced incorporating a depth-correction technique similar to what is described by Barnes, et. al., Romero, et. al, and Gucunski, et. al., a process which has been clearly demonstrated to better correlate GPR results with not only ground truth (cores, sounding) but also with

  17. Investigations of multi-particle exit channels of levels in light nuclei

    NASA Astrophysics Data System (ADS)

    Manfredi, J. J.; Charity, R. J.; Elson, J. M.; Shane, R.; Sobotka, L. G.; Chajecki, Z.; Coupland, D.; Iwasaki, H.; Kilburn, M.; Lee, J.; Lynch, W. G.; Sanetullaev, A.; Tsang, M. B.; Winkelbauer, J.; Youngs, M.; Marley, S. T.; Shetty, D. V.; Wuosmaa, A. H.; Ghosh, T. K.; Howard, M. E.; HiRA Collaboration

    2011-10-01

    The HiRA array was used to study the many-particle exit channels produced from the interactions of an E / A = 70 MeV 9C beam with a 9Be target. Correlations between these particles were studied to analyze the decays, particularly whether they occur in one prompt step or sequentially through long-lived intermediates. The five-body decay of 8C is found to occur in two steps of two proton decay through a 6Be ground-state. In the first step, the correlations between the protons clearly show the enhanced diproton character of the decay, and the second step was found to be consistent with the independently measured 6Be two-proton decay. A new mass and uncertainty for 8C were deduced from these data and used in a refit of the A = 8 data to the isobaric multiplet mass equation (IMME). The fit indicates the need for terms beyond quadratic meaning that isospin symmetry is clearly broken for the A = 8 multiplet.

  18. Fetal cardiac activity analysis during twin pregnancy using a multi-channel SQUID system

    NASA Astrophysics Data System (ADS)

    Costa Monteiro, E.; Schleussner, E.; Kausch, S.; Grimm, B.; Schneider, A.; Hall Barbosa, C.; Haueisen, J.

    2001-05-01

    The use of SQUID magnetometers for non-invasive in utero assessment of cardiac electrical disturbances has already been shown to be a valuable clinical tool. In this way, its applicability also for the complicated case of twin pregnancy, in which the proximity of the cardiac magnetic source of each fetus can hamper the individual analysis of cardiac electrical activity, is of clinical interest. In this paper, we present fetal magnetocardiography performed on a mother pregnant of twins with 26 weeks gestational age, measured inside a magnetically shielded room, by using two identical 31-channel low- Tc SQUID magnetometer systems. Each sensor array has been positioned over one of the fetuses, according to its heart position previously assessed with the aid of ultrasound measurements. The raw data is initially averaged in time and, afterwards, analyzed by means of time plots and isofield maps. The time recordings allow the study of the morphology of each fetus’ cardiac signal and the cardiac time intervals. The resultant equivalent dipole obtained from the isofield maps indicates the position and orientation of each fetus heart. The results agree with the ultrasound analysis performed immediately before the measurements and used to obtain the approximate location of the fetuses’ hearts. Since a distinct analysis of the cardiac electrical activity of each fetus could be achieved, the results indicate the potential of the fetal magnetocardiography in the individual antenatal diagnosis of each one of the fetuses of a twin pregnancy.

  19. Two-stage reference channel calibration for collocated UV and VIS Multi-Filter Rotating Shadowband Radiometers

    NASA Astrophysics Data System (ADS)

    Chen, Maosi; Davis, John; Sun, Zhibin; Gao, Wei

    2015-09-01

    Multi-Filter Rotating Shadowband Radiometer (MFRSR) and its UV version (UV-MFRSR) are ground-based instruments for measuring solar UV and VIS radiation, deployed together in field at most USDA UV-B Monitoring and Research Program (UVMRP) sites. The performance of the traditional calibration method, Langley Analysis (LA), varies with MFRSR channels and sites, resulting in less confidence in some irradiance products. A two-stage calibration method is developed. We attributed the variation in Langley Analysis performance to the monotonically changing total optical depth (TOD) in the cloud screened points. Constant TOD is an assumption in LA. Since (1) aerosol is the main source of TOD variation at the 368nm channel and (2) UV-MFRSR measures direct normal and diffuse horizontal simultaneously, we used the radiative transfer model (i.e. MODTRAN) to create the look-up table of the ratio of direct normal and diffuse (DDR) with respect to aerosol optical depth (AOD) and solar zenith angle to evaluate the quality of the Langley Offset (VLO) by giving lower weights to VLO generated from points with monotonic AOD variation. With one or two calibrated channels as Reference Channels (RC), the most stable points in RC were selected and LA was applied on those time points to generate VLO at the adjacent un-calibrated channel. The test of this method on the UV-B program site at Homestead, Florida showed that (1) The long-term trend of the original LA VLO is impacted by the monotonic changing in AOD at 368nm channel; and (2) more clustered and abundant VLO at all channels are generated compared with the original Langley method.

  20. Design, modeling, and analysis of multi-channel demultiplexer/demodulator

    NASA Technical Reports Server (NTRS)

    Lee, David D.; Woo, K. T.

    1991-01-01

    Traditionally, satellites have performed the function of a simple repeater. Newer data distribution satellite architectures, however, require demodulation of many frequency division multiplexed uplink channels by a single demultiplexer/demodulator unit, baseband processing and routing of individual voice/data circuits, and remodulation into time division multiplexed (TDM) downlink carriers. The TRW MCDD (Multichannel Demultiplexer/Multirate Demodulator) operates on a 37.4 MHz composite input signal. Individual channel data rates are either 64 Kbps or 2.048 Mbps. The wideband demultiplexer divides the input signal into 1.44 MHz segments containing either a single 2.048 Mbps channel or thirty two 64 Kbps channels. In the latter case, the narrowband demultiplexer further divides the single 1.44 MHz wideband channel into thirty two 45 KHz narrowband channels. With this approach the time domain Fast Fourier Transformation (FFT) channelizer processing capacity is matched well to the bandwidth and number of channels to be demultiplexed. By using a multirate demodulator fewer demodulators are required while achieving greater flexibility. Each demodulator can process a wideband channel or thirty two narrowband channels. Either all wideband channels, a mixture of wideband and narrowband channels, or all narrowband channels can be demodulated. The multirate demodulator approach also has lower nonrecurring costs since only one design and development effort is needed. TRW has developed a proof of concept (POC) model which fully demonstrates the signal processing fuctions of MCDD. It is capable of processing either three 2.048 Mbps channels or two 2.048 Mbps channels and thirty two 64 Kbps channels. An overview of important MCDD system engineering issues is presented as well as discussion on some of the Block Oriented System Simulation analyses performed for design verification and selection of operational parameters of the POC model. Systems engineering analysis of the POC

  1. Three-dimensional plume simulation of multi-channel thruster configuration

    NASA Astrophysics Data System (ADS)

    Taccogna, F.; Pagano, D.; Scortecci, F.; Garulli, A.

    2014-12-01

    A three-dimensional hybrid particle-in-cell model of the plume emitted by a four-channel Hall-effect thruster configuration for a preliminary design study has been developed. Results show the presence of a potential well in the central region close to the exit plane of the configuration. Together with the typical characteristics of the single channel ion energy spectrum, a double peak structure in the low energy range is present in the four-channel configuration. It is due to the geometrical effects (four-channel source) and to the anisotropic nature of ion-atom scattering.

  2. Advances in 3D soil mapping and water content estimation using multi-channel ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Moysey, S. M.

    2011-12-01

    Multi-channel ground-penetrating radar systems have recently become widely available, thereby opening new possibilities for shallow imaging of the subsurface. One advantage of these systems is that they can significantly reduce survey times by simultaneously collecting multiple lines of GPR reflection data. As a result, it is becoming more practical to complete 3D surveys - particularly in situations where the subsurface undergoes rapid changes, e.g., when monitoring infiltration and redistribution of water in soils. While 3D and 4D surveys can provide a degree of clarity that significantly improves interpretation of the subsurface, an even more powerful feature of the new multi-channel systems for hydrologists is their ability to collect data using multiple antenna offsets. Central mid-point (CMP) surveys have been widely used to estimate radar wave velocities, which can be related to water contents, by sequentially increasing the distance, i.e., offset, between the source and receiver antennas. This process is highly labor intensive using single-channel systems and therefore such surveys are often only performed at a few locations at any given site. In contrast, with multi-channel GPR systems it is possible to physically arrange an array of antennas at different offsets, such that a CMP-style survey is performed at every point along a radar transect. It is then possible to process this data to obtain detailed maps of wave velocity with a horizontal resolution on the order of centimeters. In this talk I review concepts underlying multi-channel GPR imaging with an emphasis on multi-offset profiling for water content estimation. Numerical simulations are used to provide examples that illustrate situations where multi-offset GPR profiling is likely to be successful, with an emphasis on considering how issues like noise, soil heterogeneity, vertical variations in water content and weak reflection returns affect algorithms for automated analysis of the data. Overall

  3. Simulation-Based Validation for Four-Dimensional Multi-Channel Ultrasound Current Source Density Imaging

    PubMed Central

    Wang, Zhaohui; Witte, Russell S.

    2015-01-01

    Ultrasound current source density imaging (UCSDI), which has application to the heart and brain, exploits the acoustoelectric (AE) effect and Ohm's law to detect and map an electrical current distribution. In this study, we describe 4-D UCSDI simulations of a dipole field for comparison and validation with bench-top experiments. The simulations consider the properties of the ultrasound pulse as it passes through a conductive medium, the electric field of the injected dipole, and the lead field of the detectors. In the simulation, the lead fields of detectors and electric field of the dipole were calculated by the finite element (FE) method, and the convolution and correlation in the computation of the detected AE voltage signal were accelerated using 3-D fast Fourier transforms. In the bench-top experiment, an electric dipole was produced in a bath of 0.9% NaCl solution containing two electrodes, which injected an ac pulse (200 Hz, 3 cycles) ranging from 0 to 140 mA. Stimulating and recording electrodes were placed in a custom electrode chamber made on a rapid prototype printer. Each electrode could be positioned anywhere on an x-y grid (5 mm spacing) and individually adjusted in the depth direction for precise control of the geometry of the current sources and detecting electrodes. A 1-MHz ultrasound beam was pulsed and focused through a plastic film to modulate the current distribution inside the saline-filled tank. AE signals were simultaneously detected at a sampling frequency of 15 MHz on multiple recording electrodes. A single recording electrode is sufficient to form volume images of the current flow and electric potentials. The AE potential is sensitive to the distance from the dipole, but is less sensitive to the angle between the detector and the dipole. Multi-channel UCSDI potentially improves 4-D mapping of bioelectric sources in the body at high spatial resolution, which is especially important for diagnosing and guiding treatment of cardiac and

  4. Simulation-based validation for four- dimensional multi-channel ultrasound current source density imaging.

    PubMed

    Wang, Zhaohui; Witte, Russell S

    2014-03-01

    Ultrasound current source density imaging (UCSDI), which has application to the heart and brain, exploits the acoustoelectric (AE) effect and Ohm's law to detect and map an electrical current distribution. In this study, we describe 4-D UCSDI simulations of a dipole field for comparison and validation with bench-top experiments. The simulations consider the properties of the ultrasound pulse as it passes through a conductive medium, the electric field of the injected dipole, and the lead field of the detectors. In the simulation, the lead fields of detectors and electric field of the dipole were calculated by the finite element (FE) method, and the convolution and correlation in the computation of the detected AE voltage signal were accelerated using 3-D fast Fourier transforms. In the bench-top experiment, an electric dipole was produced in a bath of 0.9% NaCl solution containing two electrodes, which injected an ac pulse (200 Hz, 3 cycles) ranging from 0 to 140 mA. Stimulating and recording electrodes were placed in a custom electrode chamber made on a rapid prototype printer. Each electrode could be positioned anywhere on an x-y grid (5 mm spacing) and individually adjusted in the depth direction for precise control of the geometry of the current sources and detecting electrodes. A 1-MHz ultrasound beam was pulsed and focused through a plastic film to modulate the current distribution inside the saline-filled tank. AE signals were simultaneously detected at a sampling frequency of 15 MHz on multiple recording electrodes. A single recording electrode is sufficient to form volume images of the current flow and electric potentials. The AE potential is sensitive to the distance from the dipole, but is less sensitive to the angle between the detector and the dipole. Multi-channel UCSDI potentially improves 4-D mapping of bioelectric sources in the body at high spatial resolution, which is especially important for diagnosing and guiding treatment of cardiac and

  5. Implementation of a miniature sized, battery powered electrophysiological signal-generator for testing multi-channel recording equipments.

    PubMed

    Máthé, Kálmán; Tóth, Attila; Petykó, Zoltán; Szabó, Imre; Czurkó, András

    2007-09-15

    Testing electrophysiological recording equipments is an important task in multi-channel extracellular in vivo electrophysiology. In this paper, a miniature, battery powered multi-channel electrophysiological signal-generator (ESG) is described that was designed for this purpose. The device is based on a Xilinx CPLD (Complex Programmable Logic Device) and it is powered by a 3V lithium coin battery. It is a useful tool for calibration and testing the performance, quality and parameters of the recording equipments used for acquiring EEG, field potentials, ECG, EMG, and multiple unit activity. The device is ideally suited to identify instances when errors interfere with the proper recording, and repair of wiring or service of the equipment is needed. Two versions of the device are described; one is for 16 (ESG16), and another is for 32 channels (ESG32). Both versions provide amplitude and time calibration, as well as cross-talk and CMRR (common mode rejection ratio) testing for the recording equipment. PMID:17624440

  6. Progress towards a 256 channel multi-anode microchannel plate photomultiplier system with picosecond timing

    PubMed Central

    Lapington, J.S.; Ashton, T.J.R.; Ross, D.; Conneely, T.

    2012-01-01

    Despite the rapid advances in solid state technologies such as the silicon photomultiplier (SiPM), microchannel plate (MCP) photomultipliers still offer a proven and practical technological solution for high channel count pixellated photon-counting systems with very high time resolution. We describe progress towards a 256 channel optical photon-counting system using CERN-developed NINO and HTDC ASICs, and designed primarily for time resolved spectroscopy in life science applications. Having previously built and demonstrated a 18 mm diameter prototype tube with an 8×8 channel readout configuration and <43 ps rms single photon timing resolution, we are currently developing a 40 mm device with a 32×32 channel readout. Initially this will be populated with a 256 channel electronics system comprising four sets of modular 64 channel preamplifier/discriminator, and time-to-digital converter units, arranged in a compact three dimensional configuration. We describe the detector and electronics design and operation, and present performance measurements from the 256 channel development system. We discuss enhancements to the system including higher channel count and the use of application specific on-board signal processing capabilities. PMID:25843997

  7. Evoked potential correlates of selective attention with multi-channel auditory inputs.

    PubMed

    Schwent, V L; Hillyard, S A

    1975-02-01

    Ten subjects were presented with a random sequence of 50 msec tone pips at a rapid rate (averaging one tone every 225 msec). The tones came from four different sound sources or sensory "channels" each having a different pitch (2000,4000,1000, and 500 c/sec respectively) and perceived spatial position (spaced equidistant across the head). Within each sensory "channel" a random 10% of the tones were of a slightly higher pitch (designated as "targets"). The subject attended to one channel at a time for 7.5 min and counted the targets in that channel. The auditory evoked vertex potential elicited by a channel of stimuli when attended was compared with the mean vertex potential elicited by those same stimuli when the other three channels were being attended. The N1 component (latency 80130 msec) measured re a baseline revealed an increase with attention (82% in the baselineN1 measure, P less than 10-). It was concluded that: (1) this N1 enhancement could not be attributed to peripheral mechanisms acting on sensory transmission; (2) this N1 enhancement reflects a "finely tuned" selective attention to one channel of stimuli among several concurrent and competing channels; and (3) a probable relationship exists between the information load on the subject and the magnitude of this EP enhancement with selective attention. PMID:45943

  8. Cross channel dependency requirements of the multi-path redundant avionics suite

    NASA Astrophysics Data System (ADS)

    Martin, Fred; Adams, Darryl

    Requirements for cross channel dependencies in the multipath redundant avionics suite (MPRAS) architecture are described. MPRAS is a data synchronous avionics architecture for space launch vehicle applications. The MPRAS cross channel data link (CCDL) provides the mechanism, required by data synchronous architectures, to exchange data and maintain synchronization among redundant channels. MPRAS architectural requirements impose a variety of characteristics for cross channel dependencies which make traditional CCDL solutions unacceptable for MPRAS target applications. The MPRAS CCDL requirements have led to a CCDL design which maintains resilience to faults, does not introduce large cross channel bandwidth reductions, and meets the other established MPRAS CCDL requirements. A review of fault-tolerant system principles applicable to CCDL issues is presented as well as a top-level functional description of the MPRAS CCDL design.

  9. Strong nonlinear saturation absorption-induced optical pinhole channel and super-resolution effects: a multi-layer system model.

    PubMed

    Wei, Jingsong; Yan, Hui

    2014-11-15

    This work focuses on the strong nonlinear saturation absorption (NSA)-induced optical super-resolution effect. A multi-layer system model is proposed to understand the strong NSA-induced formation of an optical pinhole channel and the generation of a super-resolution spot. Taking a Sb2Te3 thin film as an example, numerical simulations were conducted. The results illustrate that an optical pinhole channel is clearly formed by the NSA characteristics. This pinhole channel is similar to a near-field light probe. Light travels through the pinhole channel, and a super-resolution spot is generated at its apex. The near-field spot scanning experimental results show that the reduction ratio of the spot is approximately 44.8%, which is basically consistent with the numerical simulation result of 43%. This work is helpful for understanding optical nonlinear super-resolution effects and developing nanolithography, nanodata storage, high-resolution optical imaging technologies with nonlinear thin films. PMID:25490475

  10. Decoding the attended speech stream with multi-channel EEG: implications for online, daily-life applications

    NASA Astrophysics Data System (ADS)

    Mirkovic, Bojana; Debener, Stefan; Jaeger, Manuela; De Vos, Maarten

    2015-08-01

    Objective. Recent studies have provided evidence that temporal envelope driven speech decoding from high-density electroencephalography (EEG) and magnetoencephalography recordings can identify the attended speech stream in a multi-speaker scenario. The present work replicated the previous high density EEG study and investigated the necessary technical requirements for practical attended speech decoding with EEG. Approach. Twelve normal hearing participants attended to one out of two simultaneously presented audiobook stories, while high density EEG was recorded. An offline iterative procedure eliminating those channels contributing the least to decoding provided insight into the necessary channel number and optimal cross-subject channel configuration. Aiming towards the future goal of near real-time classification with an individually trained decoder, the minimum duration of training data necessary for successful classification was determined by using a chronological cross-validation approach. Main results. Close replication of the previously reported results confirmed the method robustness. Decoder performance remained stable from 96 channels down to 25. Furthermore, for less than 15 min of training data, the subject-independent (pre-trained) decoder performed better than an individually trained decoder did. Significance. Our study complements previous research and provides information suggesting that efficient low-density EEG online decoding is within reach.

  11. An online multi-channel SSVEP-based brain-computer interface using a canonical correlation analysis method

    NASA Astrophysics Data System (ADS)

    Bin, Guangyu; Gao, Xiaorong; Yan, Zheng; Hong, Bo; Gao, Shangkai

    2009-08-01

    In recent years, there has been increasing interest in using steady-state visual evoked potential (SSVEP) in brain-computer interface (BCI) systems. However, several aspects of current SSVEP-based BCI systems need improvement, specifically in relation to speed, user variation and ease of use. With these improvements in mind, this paper presents an online multi-channel SSVEP-based BCI system using a canonical correlation analysis (CCA) method for extraction of frequency information associated with the SSVEP. The key parameters, channel location, window length and the number of harmonics, are investigated using offline data, and the result used to guide the design of the online system. An SSVEP-based BCI system with six targets, which use nine channel locations in the occipital and parietal lobes, a window length of 2 s and the first harmonic, is used for online testing on 12 subjects. The results show that the proposed BCI system has a high performance, achieving an average accuracy of 95.3% and an information transfer rate of 58 ± 9.6 bit min-1. The positive characteristics of the proposed system are that channel selection and parameter optimization are not required, the possible use of harmonic frequencies, low user variation and easy setup.

  12. New approach to information fusion for Lipschitz classifiers ensembles: Application in multi-channel C-OTDR-monitoring systems

    NASA Astrophysics Data System (ADS)

    Timofeev, Andrey V.; Egorov, Dmitry V.

    2016-06-01

    This paper presents new results concerning selection of an optimal information fusion formula for an ensemble of Lipschitz classifiers. The goal of information fusion is to create an integral classificatory which could provide better generalization ability of the ensemble while achieving a practically acceptable level of effectiveness. The problem of information fusion is very relevant for data processing in multi-channel C-OTDR-monitoring systems. In this case we have to effectively classify targeted events which appear in the vicinity of the monitored object. Solution of this problem is based on usage of an ensemble of Lipschitz classifiers each of which corresponds to a respective channel. We suggest a brand new method for information fusion in case of ensemble of Lipschitz classifiers. This method is called "The Weighing of Inversely as Lipschitz Constants" (WILC). Results of WILC-method practical usage in multichannel C-OTDR monitoring systems are presented.

  13. Calibrated multi-subband Monte Carlo modeling of tunnel-FETs in silicon and III-V channel materials

    NASA Astrophysics Data System (ADS)

    Revelant, A.; Palestri, P.; Osgnach, P.; Selmi, L.

    2013-10-01

    We present a semiclassical model for Tunnel-FET (TFET) devices capable to describe band-to-band tunneling (BtBT) as well as far from equilibrium transport of the generated carriers. BtBT generation is implemented as an add-on into an existing multi-subband Monte Carlo (MSMC) transport simulator that accounts as well for the effects typical to alternative channel materials and high-κ dielectrics. A simple but accurate correction for the calculation of the BtBT generation rate to account for carrier confinement in the subbands is proposed and verified by comparison with full 2D quantum calculation.

  14. Demonstration of a multi-channel, low-profile wire gauge for tracing wave development and detonation turning in explosives

    SciTech Connect

    Skidmore, Bradley E; Novak, Alan M; Zucker, Jonathan M; Parker, Jr, Gary R; Dickson, Peter; Foley, Timothy J; Trebs, Adam A

    2010-01-01

    The multi-channel low-profile wire gauge is a device which measures high pressure wave position via the continuous variation in length of a conductor in conjunction with a fiducial, allowing in situ measurement of wave front curvature during wave development. The gauge's low profile ({approx}250 {micro}m) and high resolution measurements (up to 0.5 nanoseconds) make it minimally intrusive and highly responsive, with a typically wave position accuracy of {+-}1 mm. Gauge construction and data analysis methods are described and waveforms are presented for Detasheet and N-9 explosives.

  15. A new multi-channel SAR-GMTI algorithm based on frequency STAP and FrFT

    NASA Astrophysics Data System (ADS)

    Wei, Jun; Yuan, Yunneng; Sun, Jingping; Liu, Shujun; Mao, Shiyi

    2007-11-01

    A SAR-GMTI algorithm based on space-time adaptive processing (STAP) in frequency domain by multi-channel SAR is proposed. The paper deduces the theoretical formula of the clutter suppression in-depth based on frequency STAP and finds that the output is a chirp signal and similar to the input signal of the moving targets before suppressed, so FrFT is chosen to detect them and estimate their moving parameters. The analyses in theory and simulator results show that our new algorithm is effective.

  16. Plasmonic Nanoholes in a Multi-Channel Microarray Format for Parallel Kinetic Assays and Differential Sensing

    PubMed Central

    Im, Hyungsoon; Lesuffleur, Antoine; Lindquist, Nathan C.; Oh, Sang-Hyun

    2009-01-01

    We present nanohole arrays in a gold film integrated with a 6-channel microfluidic chip for parallel measurements of molecular binding kinetics. Surface plasmon resonance effects in the nanohole arrays enable real-time label-free measurements of molecular binding events in each channel, while adjacent negative reference channels can record measurement artifacts such as bulk solution index changes, temperature variations, or changing light absorption in the liquid. Using this platform, streptavidin-biotin specific binding kinetics are measured at various concentrations with negative controls. A high-density microarray of 252 biosensing pixels is also demonstrated with a packing density of 106 sensing elements/cm2, which can potentially be coupled with a massively parallel array of microfluidic channels for protein microarray applications. PMID:19284776

  17. Optical transmission modules for multi-channel superconducting quantum interference device readouts

    SciTech Connect

    Kim, Jin-Mok Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong

    2013-12-15

    We developed an optical transmission module consisting of 16-channel analog-to-digital converter (ADC), digital-noise filter, and one-line serial transmitter, which transferred Superconducting Quantum Interference Device (SQUID) readout data to a computer by a single optical cable. A 16-channel ADC sent out SQUID readouts data with 32-bit serial data of 8-bit channel and 24-bit voltage data at a sample rate of 1.5 kSample/s. A digital-noise filter suppressed digital noises generated by digital clocks to obtain SQUID modulation as large as possible. One-line serial transmitter reformed 32-bit serial data to the modulated data that contained data and clock, and sent them through a single optical cable. When the optical transmission modules were applied to 152-channel SQUID magnetoencephalography system, this system maintained a field noise level of 3 fT/√Hz @ 100 Hz.

  18. Optical transmission modules for multi-channel superconducting quantum interference device readouts

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Mok; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong

    2013-12-01

    We developed an optical transmission module consisting of 16-channel analog-to-digital converter (ADC), digital-noise filter, and one-line serial transmitter, which transferred Superconducting Quantum Interference Device (SQUID) readout data to a computer by a single optical cable. A 16-channel ADC sent out SQUID readouts data with 32-bit serial data of 8-bit channel and 24-bit voltage data at a sample rate of 1.5 kSample/s. A digital-noise filter suppressed digital noises generated by digital clocks to obtain SQUID modulation as large as possible. One-line serial transmitter reformed 32-bit serial data to the modulated data that contained data and clock, and sent them through a single optical cable. When the optical transmission modules were applied to 152-channel SQUID magnetoencephalography system, this system maintained a field noise level of 3 fT/√Hz @ 100 Hz.

  19. Optical transmission modules for multi-channel superconducting quantum interference device readouts.

    PubMed

    Kim, Jin-Mok; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong

    2013-12-01

    We developed an optical transmission module consisting of 16-channel analog-to-digital converter (ADC), digital-noise filter, and one-line serial transmitter, which transferred Superconducting Quantum Interference Device (SQUID) readout data to a computer by a single optical cable. A 16-channel ADC sent out SQUID readouts data with 32-bit serial data of 8-bit channel and 24-bit voltage data at a sample rate of 1.5 kSample/s. A digital-noise filter suppressed digital noises generated by digital clocks to obtain SQUID modulation as large as possible. One-line serial transmitter reformed 32-bit serial data to the modulated data that contained data and clock, and sent them through a single optical cable. When the optical transmission modules were applied to 152-channel SQUID magnetoencephalography system, this system maintained a field noise level of 3 fT/√Hz @ 100 Hz. PMID:24387470

  20. Evoked potential correlates of selective attention with multi-channel auditory inputs

    NASA Technical Reports Server (NTRS)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  1. Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton

    PubMed Central

    Grimm, Florian; Gharabaghi, Alireza

    2016-01-01

    Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement. PMID:27445658

  2. Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton.

    PubMed

    Grimm, Florian; Gharabaghi, Alireza

    2016-01-01

    Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement. PMID:27445658

  3. Determination of optimal lot size and production rate for multi-production channels with limited capacity

    NASA Astrophysics Data System (ADS)

    Huang, Yeu-Shiang; Wang, Ruei-Pei; Ho, Jyh-Wen

    2015-07-01

    Due to the constantly changing business environment, producers often have to deal with customers by adopting different procurement policies. That is, manufacturers confront not only predictable and regular orders, but also unpredictable and irregular orders. In this study, from the perspective of upstream manufacturers, both regular and irregular orders are considered in coping with the situation in which an uncertain demand is faced by the manufacturer, and a capacity confirming mechanism is used to examine such demand. If the demand is less than or equal to the capacity of the ordinary production channel, the general supply channel is utilised to fully account for the manufacturing process, but if the demand is greater than the capacity of the ordinary production channel, the contingency production channel would be activated along with the ordinary channel to satisfy the upcoming high demand. Besides, the reproductive property of the probability distribution is employed to represent the order quantity of the two types of demand. Accordingly, the optimal production rates and lot sizes for both channels are derived to provide managers with insights for further production planning.

  4. TARGET: A multi-channel digitizer chip for very-high-energy gamma-ray telescopes

    SciTech Connect

    Bechtol, K.; Funk, S.; Okumura, A.; Ruckman, L.; Simons, A.; Tajima, H.; Vandenbroucke, J.; Varner, G.; /Hawaii U.

    2011-08-11

    The next-generation very-high-energy (VHE) gamma-ray observatory, the Cherenkov Telescope Array, will feature dozens of imaging atmospheric Cherenkov telescopes (IACTs), each with thousands of pixels of photosensors. To be affordable and reliable, reading out such a mega-channel array requires event recording technology that is highly integrated and modular, with a low cost per channel. We present the design and performance of a chip targeted to this application: the TeV Array Readout with GSa/s sampling and Event Trigger (TARGET). This application-specific integrated circuit (ASIC) has 16 parallel input channels, a 4096-sample buffer for each channel, adjustable input termination, self-trigger functionality, and tight window-selected readout. We report the performance of TARGET in terms of sampling frequency, power consumption, dynamic range, current-mode gain, analog bandwidth, and cross talk. The large number of channels per chip allows a low cost per channel ($10 to $20 including front-end and back-end electronics but not including photosensors) to be achieved with a TARGET-based IACT readout system. In addition to basic performance parameters of the TARGET chip itself, we present a camera module prototype as well as a second-generation chip (TARGET 2), both of which have been produced.

  5. Modelling Temporal Stability of EPI Time Series Using Magnitude Images Acquired with Multi-Channel Receiver Coils

    PubMed Central

    Hutton, Chloe; Balteau, Evelyne; Lutti, Antoine; Josephs, Oliver; Weiskopf, Nikolaus

    2012-01-01

    In 2001, Krueger and Glover introduced a model describing the temporal SNR (tSNR) of an EPI time series as a function of image SNR (SNR0). This model has been used to study physiological noise in fMRI, to optimize fMRI acquisition parameters, and to estimate maximum attainable tSNR for a given set of MR image acquisition and processing parameters. In its current form, this noise model requires the accurate estimation of image SNR. For multi-channel receiver coils, this is not straightforward because it requires export and reconstruction of large amounts of k-space raw data and detailed, custom-made image reconstruction methods. Here we present a simple extension to the model that allows characterization of the temporal noise properties of EPI time series acquired with multi-channel receiver coils, and reconstructed with standard root-sum-of-squares combination, without the need for raw data or custom-made image reconstruction. The proposed extended model includes an additional parameter κ which reflects the impact of noise correlations between receiver channels on the data and scales an apparent image SNR (SNR′0) measured directly from root-sum-of-squares reconstructed magnitude images so that κ = SNR′0/SNR0 (under the condition of SNR0>50 and number of channels ≤32). Using Monte Carlo simulations we show that the extended model parameters can be estimated with high accuracy. The estimation of the parameter κ was validated using an independent measure of the actual SNR0 for non-accelerated phantom data acquired at 3T with a 32-channel receiver coil. We also demonstrate that compared to the original model the extended model results in an improved fit to human task-free non-accelerated fMRI data acquired at 7T with a 24-channel receiver coil. In particular, the extended model improves the prediction of low to medium tSNR values and so can play an important role in the optimization of high-resolution fMRI experiments at lower SNR levels. PMID:23284874

  6. GaN-based multi-two-dimensional-electron-gas-channel diodes on sapphire substrates with breakdown voltage of over 3 kV

    NASA Astrophysics Data System (ADS)

    Terano, Akihisa; Tsuchiya, Tomonobu; Mochizuki, Kazuhiro; Tanaka, Shigehisa; Nakamura, Tohru

    2015-06-01

    We investigated the achievability of low specific on-resistance and high breakdown voltage by GaN diodes consisting of three, five, and eight two-dimensional-electron-gas (2DEG) channels. The anode Schottky electrode and cathode Ohmic electrode were formed on each side wall of the multi-2DEG-channel and the n-type region was formed by Si-ion implantation in the cathode electrode-formation area of each multi-2DEG-channel. With increasing number of 2DEG channels of the diodes, specific on-resistance (RonA) showed a tendency to decrease; RonA of eight-2DEG-channel diodes was as low as 12.1 mΩ cm2. The breakdown voltage of all the fabricated diodes exceeded 3 kV. Although the electrical characteristics of the multi-2DEG-channel diodes fabricated on sapphire substrates were demonstrated, the number of cracks appearing on the epitaxial layer surface was found to increase with increasing number of 2DEG channels. Such crack formation was concluded to govern the practical limit for the number of 2DEG channels.

  7. A Radiation Hard Multi-Channel Digitizer ASIC for Operation in the Harsh Jovian Environment

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Aslam, S.; Akturk, A.; Quilligan, G.

    2011-01-01

    ultimately impact the surface of Europa after the mission is completed. The current JEO mission concept includes a range of instruments on the payload, to monitor dynamic phenomena (such as Io's volcanoes and Jupiters atmosphere), map the Jovian magnetosphere and its interactions with the Galilean satellites, and characterize water oceans beneath the ice shells of Europa and Ganymede. The payload includes a low mass (3.7 Kg) and low power (< 5 W) Thermal Instrument (TI) concept for measuring possible warm thermal anomalies on Europa s cold surface caused by recent (< 10,000 years) eruptive activity. Regions of anomalously high heat flow will be identified by thermal mapping using a nadir pointing, push-broom filter radiometer that provides far-IR imagery in two broad band spectral wavelength regions, 8-20 m and 20-100 m, for surface temperature measurements with better than a 2 K accuracy and a spatial resolution of 250 m/pixel obtained from a 100 Km orbit. The temperature accuracy permits a search for elevated temperatures when combined with albedo information. The spatial resolution is sufficient to resolve Europa's larger cracks and ridge axial valleys. In order to accomplish the thermal mapping, the TI uses sensitive thermopile arrays that are readout by a custom designed low-noise Multi-Channel Digitizer (MCD) ASIC that resides very close to the thermopile linear array outputs. Both the thermopile array and the MCD ASIC will need to show full functionality within the harsh Jovian radiation environment, operating at cryogenic temperatures, typically 150 K to 170 K. In the following, a radiation mitigation strategy together with a low risk Radiation-Hardened-By-Design (RHBD) methodology using commercial foundry processes is given for the design and manufacture of a MCD ASIC that will meet this challenge.

  8. Taipei's Use of a Multi-Channel Mass Risk Communication Program to Rapidly Reverse an Epidemic of Highly Communicable Disease

    PubMed Central

    Yen, Muh-Yong; Wu, Tsung-Shu Joseph; Chiu, Allen Wen-Hsiang; Wong, Wing-Wai; Wang, Po-En; Chan, Ta-Chien; King, Chwan-Chuen

    2009-01-01

    Background In September 2007, an outbreak of acute hemorrhagic conjunctivitis (AHC) occurred in Keelung City and spread to Taipei City. In response to the epidemic, a new crisis management program was implemented and tested in Taipei. Methodology and Principal Findings Having noticed that transmission surged on weekends during the Keelung epidemic, Taipei City launched a multi-channel mass risk communications program that included short message service (SMS) messages sent directly to approximately 2.2 million Taipei residents on Friday, October 12th, 2007. The public was told to keep symptomatic students from schools and was provided guidelines for preventing the spread of the disease at home. Epidemiological characteristics of Taipei's outbreak were analyzed from 461 sampled AHC cases. Median time from exposure to onset of the disease was 1 day. This was significantly shorter for cases occurring in family clusters than in class clusters (mean±SD: 2.6±3.2 vs. 4.39±4.82 days, p = 0.03), as well as for cases occurring in larger family clusters as opposed to smaller ones (1.2±1.7 days vs. 3.9±4.0 days, p<0.01). Taipei's program had a significant impact on patient compliance. Home confinement of symptomatic children increased from 10% to 60% (p<0.05) and helped curb the spread of AHC. Taipei experienced a rapid decrease in AHC cases between the Friday of the SMS announcement and the following Monday, October 15, (0.70% vs. 0.36%). By October 26, AHC cases reduced to 0.01%. The success of this risk communication program in Taipei (as compared to Keelung) is further reflected through rapid improvements in three epidemic indicators: (1) significantly lower crude attack rates (1.95% vs. 14.92%, p<0.001), (2) a short epidemic period of AHC (13 vs. 34 days), and (3) a quick drop in risk level (1∼2 weeks) in Taipei districts that border Keelung (the original domestic epicenter). Conclusions and Significance The timely launch of this systematic, communication

  9. Model Based Prediction of Uplink Multi-Path Fading Channel Response for Pre-Equalization in Mobile MC-CDMA Systems

    NASA Astrophysics Data System (ADS)

    Mkrtchyan, Gagik; Naito, Katsuhiro; Mori, Kazuo; Kobayashi, Hideo

    Multi-carrier code division multiple access (MC-CDMA) has been considered as one of the promising techniques for the next generation of mobile communication systems because of its efficient bandwidth usage, robustness to the multi-path fading and simple channel-sharing scheme. However, MC-CDMA cannot be employed in the uplink communication where the transmitted signal from each user propagates through the different multi-path fading channel, and the received signals are no longer orthogonal at the base station. As a result, bit error rate (BER) performance in the uplink MC-CDMA communication would be strongly degraded due to the occurrence of multi-user interference (MUI). To solve the MUI problem in the uplink MC-CDMA, the pre-equalization method was proposed in which the uplink signal is pre-equalized at the user terminal by using the channel response estimated from the downlink. Although the pre-equalization method is very effective for the stationary uplink channel with fixed users, it is hard to be employed in the time varying fading channel with mobile users, because there is a big difference in the channel responses between downlink and uplink. For the efficient MUI compensation, each user terminal would be required to predict the future channel conditions based on the current observation. This paper proposes a method for model based uplink channel response prediction by employing the spectral decomposition of the downlink channel impulse response. Computer simulation results show that the proposed method can achieve the accurate prediction of channel response for mobile users during the uplink transmission and allows the effective MUI compensation.

  10. Investigation of Depth of Interaction Encoding for a Pixelated LSO Array with a Single Multi-Channel PMT.

    PubMed

    Yang, Yongfeng; Wu, Yibao; Cherry, Simon R

    2009-10-01

    A new approach to depth of interaction (DOI) encoding for a pixelated LSO array using a single multi-channel PMT was investigated. In this method the DOI information was estimated by taking advantage of optical crosstalk between LSO elements and examining the standard deviation (spread) of signals on all channels of the PMT. Unpolished and polished 6×6 LSO arrays with a crystal size of 1.3×1.3×20 mm(3) were evaluated on a Hamamatsu H7546 64-channel PMT. The arrays were placed on the center of the PMT and the central 16 channels of the PMT were individually read out and digitized. For the unpolished array, all crystals were resolved in the flood histogram. An average DOI resolution of 8 mm was obtained. The energy resolution was ∼25% after the signal amplitude was corrected using the measured DOI information. For the polished array, the flood histogram was superior to the unpolished array, however no DOI information could be measured. Using unpolished crystals, this method could be a practical way to achieve limited DOI information in PET detectors. The standard deviation of all PMT channels can be readily obtained using a resistor network. Only five signals (four signals to determine the x-y position and one signal measuring the standard deviation) need to be digitized, and this method only requires a single photon detector to read out the array. Unlike phoswich detectors, the method does not require segmenting the scintillator array into layers. The measured DOI resolution was much worse than that obtained with the dual-ended readout method, however, it was similar to that obtained with a two-layer phoswich detector. PMID:20046796

  11. Energetics of Multi-Ion Conduction Pathways in Potassium Ion Channels

    PubMed Central

    2013-01-01

    Potassium ion channels form pores in cell membranes, allowing potassium ions through while preventing the passage of sodium ions. Despite numerous high-resolution structures, it is not yet possible to relate their structure to their single molecule function other than at a qualitative level. Over the past decade, there has been a concerted effort using molecular dynamics to capture the thermodynamics and kinetics of conduction by calculating potentials of mean force (PMF). These can be used, in conjunction with the electro-diffusion theory, to predict the conductance of a specific ion channel. Here, we calculate seven independent PMFs, thereby studying the differences between two potassium ion channels, the effect of the CHARMM CMAP forcefield correction, and the sensitivity and reproducibility of the method. Thermodynamically stable ion–water configurations of the selectivity filter can be identified from all the free energy landscapes, but the heights of the kinetic barriers for potassium ions to move through the selectivity filter are, in nearly all cases, too high to predict conductances in line with experiment. This implies it is not currently feasible to predict the conductance of potassium ion channels, but other simpler channels may be more tractable. PMID:24353479

  12. Multi-channel purge and trap system coupled with ion chromatography for the determination of alkylamines in cosmetics.

    PubMed

    Zhong, Zhixiong; Li, Gongke; Luo, Zhibin; Zhu, Binghui

    2012-02-17

    A new multi-channel purge and trap system coupled with ion chromatography for the determination of six alkylamines in cosmetics was developed. The proposed method, based on purge and trap of the volatile alkylamines, involved in a miniaturization and multi-channel integration of classical steam distillation and a simple approach for routine labs. The procedure was rapidly achieved within 10 min and the matrix interferences could be effectively eliminated. Sample pretreatment frequency was higher than 40 h(-1). The linear ranges were 0.1-15 mg L(-1) and the detection limits varied from 0.023 to 0.038 mg L(-1). This method was successfully utilized to determine the amounts of alkylamines in cosmetics with recoveries ranging from 80.3 to 105.5% and the relative standard deviations (RSDs) ranging from 0.78 to 7.5%. It was proved to be accurate, time-saving, and suitable for the determination of large numbers of cosmetics in a short time. PMID:22244166

  13. High repetition rate multi-channel source of high-power rf-modulated pulses

    NASA Astrophysics Data System (ADS)

    Ulmaskulov, M. R.; Pedos, M. S.; Rukin, S. N.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Yalandin, M. I.; Romanchenko, I. V.; Rostov, V. V.

    2015-07-01

    This paper presents the results of testing a high voltage pulse generator based on parallel gyromagnetic nonlinear transmission lines filled with saturable ferrite. The generator is capable of producing almost identical stable rf-modulated nanosecond high voltage pulses in each of the two, or four, parallel output channels. The output voltage amplitude in each channel can reach -285 or -180 kV, respectively, with a rf modulation depth of up to 60%. Drive pulses were produced as the packets of duration 1-5 s at a pulse repetition frequency of 800 Hz using a driver equipped with all-solid-state switches. Splitting the driver pulse provided electric field strengths in the channels which were below the breakdown field strength of the transmission lines. As a result, the use of nonlinear transmission lines of reduced diameter made it possible to increase the center frequency of the excited rf oscillations to ˜2 GHz.

  14. Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

    NASA Astrophysics Data System (ADS)

    Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

    2016-03-01

    In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

  15. Channeling radiation of multi-GeV positrons in single crystals

    NASA Astrophysics Data System (ADS)

    Chirkov, P. N.; Chesnokov, Y. A.; Maisheev, V. A.; Bolognini, D.; Hasan, S.; Prest, M.; Vallazza, E.

    2016-04-01

    The process of radiation of 120 GeV positrons moving in a channeling regime in (011) plane of a single crystal was considered. At the beginning on the basis of the theory of nonlinear oscillations, the trajectory of moving positrons at different initial conditions was derived. Then taking into account the nonlinearity of motion, the distribution function over oscillation amplitudes of channeling particles was found. After this, the intensity of radiation at different initial conditions was calculated with the help of two various methods. These results may be useful for comparison with experimental data at positron energies from 100 and more GeV.

  16. Smart multi-channel two-dimensional micro-gas chromatography for rapid workplace hazardous volatile organic compounds measurement.

    PubMed

    Liu, Jing; Seo, Jung Hwan; Li, Yubo; Chen, Di; Kurabayashi, Katsuo; Fan, Xudong

    2013-03-01

    We developed a novel smart multi-channel two-dimensional (2-D) micro-gas chromatography (μGC) architecture that shows promise to significantly improve 2-D μGC performance. In the smart μGC design, a non-destructive on-column gas detector and a flow routing system are installed between the first dimensional separation column and multiple second dimensional separation columns. The effluent from the first dimensional column is monitored in real-time and decision is then made to route the effluent to one of the second dimensional columns for further separation. As compared to the conventional 2-D μGC, the greatest benefit of the smart multi-channel 2-D μGC architecture is the enhanced separation capability of the second dimensional column and hence the overall 2-D GC performance. All the second dimensional columns are independent of each other, and their coating, length, flow rate and temperature can be customized for best separation results. In particular, there is no more constraint on the upper limit of the second dimensional column length and separation time in our architecture. Such flexibility is critical when long second dimensional separation is needed for optimal gas analysis. In addition, the smart μGC is advantageous in terms of elimination of the power intensive thermal modulator, higher peak amplitude enhancement, simplified 2-D chromatogram re-construction and potential scalability to higher dimensional separation. In this paper, we first constructed a complete smart 1 × 2 channel 2-D μGC system, along with an algorithm for automated control/operation of the system. We then characterized and optimized this μGC system, and finally employed it in two important applications that highlight its uniqueness and advantages, i.e., analysis of 31 workplace hazardous volatile organic compounds, and rapid detection and identification of target gas analytes from interference background. PMID:23303462

  17. Channel Efficiency with Security Enhancement for Remote Condition Monitoring of Multi Machine System Using Hybrid Huffman Coding

    NASA Astrophysics Data System (ADS)

    Datta, Jinia; Chowdhuri, Sumana; Bera, Jitendranath

    2015-07-01

    This paper presents a novel scheme of remote condition monitoring of multi machine system where a secured and coded data of induction machine with different parameters is communicated between a state-of-the-art dedicated hardware Units (DHU) installed at the machine terminal and a centralized PC based machine data management (MDM) software. The DHUs are built for acquisition of different parameters from the respective machines, and hence are placed at their nearby panels in order to acquire different parameters cost effectively during their running condition. The MDM software collects these data through a communication channel where all the DHUs are networked using RS485 protocol. Before transmitting, the parameter's related data is modified with the adoption of differential pulse coded modulation (DPCM) and Huffman coding technique. It is further encrypted with a private key where different keys are used for different DHUs. In this way a data security scheme is adopted during its passage through the communication channel in order to avoid any third party attack into the channel. The hybrid mode of DPCM and Huffman coding is chosen to reduce the data packet length. A MATLAB based simulation and its practical implementation using DHUs at three machine terminals (one healthy three phase, one healthy single phase and one faulty three phase machine) proves its efficacy and usefulness for condition based maintenance of multi machine system. The data at the central control room are decrypted and decoded using MDM software. In this work it is observed that Chanel efficiency with respect to different parameter measurements has been increased very much.

  18. Fundamental studies on initiation and evolution of multi-channel discharges and their application to next generation pulsed power machines.

    SciTech Connect

    Schwarz, Jens; Savage, Mark E.; Lucero, Diego Jose; Jaramillo, Deanna M.; Seals, Kelly Gene; Pitts, Todd Alan; Hautzenroeder, Brenna M.; Laine, Mark Richard; Karelitz, David B.; Porter, John L.

    2014-09-01

    Future pulsed power systems may rely on linear transformer driver (LTD) technology. The LTD's will be the building blocks for a driver that can deliver higher current than the Z-Machine. The LTD's would require tens of thousands of low inductance ( %3C 85nH), high voltage (200 kV DC) switches with high reliability and long lifetime ( 10 4 shots). Sandia's Z-Machine employs 36 megavolt class switches that are laser triggered by a single channel discharge. This is feasible for tens of switches but the high inductance and short switch life- time associated with the single channel discharge are undesirable for future machines. Thus the fundamental problem is how to lower inductance and losses while increasing switch life- time and reliability. These goals can be achieved by increasing the number of current-carrying channels. The rail gap switch is ideal for this purpose. Although those switches have been extensively studied during the past decades, each effort has only characterized a particular switch. There is no comprehensive understanding of the underlying physics that would allow predictive capability for arbitrary switch geometry. We have studied rail gap switches via an extensive suite of advanced diagnostics in synergy with theoretical physics and advanced modeling capability. Design and topology of multichannel switches as they relate to discharge dynamics are investigated. This involves electrically and optically triggered rail gaps, as well as discrete multi-site switch concepts.

  19. Benchmarking and qualification of the NUFREQ-NPW code for best estimate prediction of multi-channel core stability margins

    SciTech Connect

    Taleyarkhan, R.; Lahey, R.T. Jr.; McFarlane, A.F.; Podowski, M.Z.

    1988-01-01

    The NUFREQ-NPW code was modified and set up at Westinghouse, USA for mixed fuel type multi-channel core-wide stability analysis. The resulting code, NUFREQ-NPW, allows for variable axial power profiles between channel groups and can handle mixed fuel types. Various models incorporated into NUFREQ-NPW were systematically compared against the Westinghouse channel stability analysis code MAZDA-NF, for which the mathematical model was developed, in an entirely different manner. Excellent agreement was obtained which verified the thermal-hydraulic modeling and coding aspects. Detailed comparisons were also performed against nuclear-coupled reactor core stability data. All thirteen Peach Bottom-2 EOC-2/3 low flow stability tests were simulated. A key aspect for code qualification involved the development of a physically based empirical algorithm to correct for the effect of core inlet flow development on subcooled boiling. Various other modeling assumptions were tested and sensitivity studies performed. Good agreement was obtained between NUFREQ-NPW predictions and data. Moreover, predictions were generally on the conservative side. The results of detailed direct comparisons with experimental data using the NUFREQ-NPW code; have demonstrated that BWR core stability margins are conservatively predicted, and all data trends are captured with good accuracy. The methodology is thus suitable for BWR design and licensing purposes. 11 refs., 12 figs., 2 tabs.

  20. A multi-channel image reconstruction method for grating-based X-ray phase-contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Xu, Qiaofeng; Sawatzky, Alex; Anastasio, Mark A.

    2014-03-01

    In this work, we report on the development of an advanced multi-channel (MC) image reconstruction algorithm for grating-based X-ray phase-contrast computed tomography (GB-XPCT). The MC reconstruction method we have developed operates by concurrently, rather than independently as is done conventionally, reconstructing tomographic images of the three object properties (absorption, small-angle scattering, refractive index). By jointly estimating the object properties by use of an appropriately defined penalized weighted least squares (PWLS) estimator, the 2nd order statistical properties of the object property sinograms, including correlations between them, can be fully exploited to improve the variance vs. resolution tradeoff of the reconstructed images as compared to existing methods. Channel-independent regularization strategies are proposed. To solve the MC reconstruction problem, we developed an advanced algorithm based on the proximal point algorithm and the augmented Lagrangian method. By use of experimental and computer-simulation data, we demonstrate that by exploiting inter-channel noise correlations, the MC reconstruction method can improve image quality in GB-XPCT.

  1. A Multi-Chamber System for Analyzing the Outgassing, Deposition,and Associated Optical Degradation Properties of Materials in a Vacuum

    SciTech Connect

    Singal, Jack; Schindler, Rafe; Chang, Chihway; Czodrowski, Patrick; Kim, Peter; /KIPAC, Menlo Park /SLAC /Stanford U.

    2009-12-11

    We report on the Camera Materials Test Chamber, a multi-vessel apparatus which analyzes the outgassing consequences of candidate materials for use in the vacuum cryostat of a new telescope camera. The system measures the outgassing products and rates of samples of materials at different temperatures, and collects films of outgassing products to measure the effects on light transmission in six optical bands. The design of the apparatus minimizes potential measurement errors introduced by background contamination.

  2. Study of Multi Pass Equal Channel Angular Pressing Using 3D Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Setia, Rajat; Sharma, Rahul Swarup; Sharma, Shanti Swarup; Raj, K. Hans

    2011-01-01

    Equal Channel Angular Pressing (ECAP) has emerged as most prominent Severe Plastic Deformation (SPD) technique used to produce an ultrafine grained (UFG) structure in metals in order to improve their mechanical and physical properties. In this work Finite Element modeling of ECAP is attempted in FORGE 2007 environment. Four passes of the ECAP process of 10mm square shaped AL 6061 billet were carried out for routes A, BA and C for different channel angles and values of coefficient of friction to investigate their influence on the billet. The models were developed assuming a range of friction conditions at the billet-die contact region considering eight distinct friction coefficient (μ) values of 0.0, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 and 0.40, respectively. The simulations are carried out using three distinct situations of die channel angles (Φ), 90°, 105°, and 120° respectively. Route `BA' emerged as a better method among the three routes studied and 90° channel angle appeared to be optimal in terms of producing high equivalent strain.

  3. Assessing the performance of multi-purpose channel management measures at increasing scales

    NASA Astrophysics Data System (ADS)

    Wilkinson, Mark; Addy, Steve

    2016-04-01

    In addition to hydroclimatic drivers, sediment deposition from high energy river systems can reduce channel conveyance capacity and lead to significant increases in flood risk. There is an increasing recognition that we need to work with the interplay of natural hydrological and morphological processes in order to attenuate flood flows and manage sediment (both coarse and fine). This typically includes both catchment (e.g. woodland planting, wetlands) and river (e.g. wood placement, floodplain reconnection) restoration approaches. The aim of this work was to assess at which scales channel management measures (notably wood placement and flood embankment removal) are most appropriate for flood and sediment management in high energy upland river systems. We present research findings from two densely instrumented research sites in Scotland which regularly experience flood events and have associated coarse sediment problems. We assessed the performance of a range of novel trial measures for three different scales: wooded flow restrictors and gully tree planting at the small scale (<1 km2), floodplain tree planting and engineered log jams at the intermediate scale (5-60 km2), and flood embankment lowering at the large scale (350 km2). Our results suggest that at the smallest scale, care is needed in the installation of flow restrictors. It was found for some restrictors that vertical erosion can occur if the tributary channel bed is disturbed. Preliminary model evidence suggested they have a very limited impact on channel discharge and flood peak delay owing to the small storage areas behind the structures. At intermediate scales, the ability to trap sediment by engineered log jams was limited. Of the 45 engineered log jams installed, around half created a small geomorphic response and only 5 captured a significant amount of coarse material (during one large flood event). As scale increases, the chance of damage or loss of wood placement is greatest. Monitoring

  4. Implementation of the multi-channel monolith reactor in an optimisation procedure for heterogeneous oxidation catalysts based on genetic algorithms.

    PubMed

    Breuer, Christian; Lucas, Martin; Schütze, Frank-Walter; Claus, Peter

    2007-01-01

    A multi-criteria optimisation procedure based on genetic algorithms is carried out in search of advanced heterogeneous catalysts for total oxidation. Simple but flexible software routines have been created to be applied within a search space of more then 150,000 individuals. The general catalyst design includes mono-, bi- and trimetallic compositions assembled out of 49 different metals and depleted on an Al2O3 support in up to nine amount levels. As an efficient tool for high-throughput screening and perfectly matched to the requirements of heterogeneous gas phase catalysis - especially for applications technically run in honeycomb structures - the multi-channel monolith reactor is implemented to evaluate the catalyst performances. Out of a multi-component feed-gas, the conversion rates of carbon monoxide (CO) and a model hydrocarbon (HC) are monitored in parallel. In combination with further restrictions to preparation and pre-treatment a primary screening can be conducted, promising to provide results close to technically applied catalysts. Presented are the resulting performances of the optimisation process for the first catalyst generations and the prospect of its auto-adaptation to specified optimisation goals. PMID:17266517

  5. Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor

    PubMed Central

    Charles, Paul T.; Adams, Andre A.; Howell, Peter B.; Trammell, Scott A.; Deschamps, Jeffrey R.; Kusterbeck, Anne W.

    2010-01-01

    Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1–10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. PMID:22315573

  6. Fluorescence-based sensing of 2,4,6-trinitrotoluene (TNT) using a multi-channeled poly(methyl methacrylate) (PMMA) microimmunosensor.

    PubMed

    Charles, Paul T; Adams, Andre A; Howell, Peter B; Trammell, Scott A; Deschamps, Jeffrey R; Kusterbeck, Anne W

    2010-01-01

    Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. PMID:22315573

  7. Analyzing the Multi-scale Interactions of Tropical Waves and Tropical Cyclone Formation with the NASA CMAVis System

    NASA Astrophysics Data System (ADS)

    Shen, B.; Nelson, B.; Tao, W.

    2011-12-01

    Among the scenarios in the Decadal Survey (DS) Missions, the advanced data processing group at the ESTO AIST PI workshop identified "Extreme Event Warning" and "Climate Projections" as two of the top priority scenarios. Recently, we (e.g., Shen et al., 2010a,b; 2011a,b) have made attempt of addressing the first by successfully developing the NASA Coupled Advanced global multiscale Modeling and concurrent Visualization systems (CAMVis) on NASA supercomputers, and demonstrating a great potential for extending the lead time (from 5~7 days up to 20 days) of tropical cyclone (TC) prediction with improved multi-scale interactions between a TC with large-scale environmental conditions such as African Easterly Waves (AEWs), and Madden Julian Oscillation (MJOs). In order to increase our confidence in long-term TC prediction and thus TC climate projection, the predictive relationships between large-scale tropical waves and TC formation need to be further examined and verified with massive model and satellite data sets. To achieve this goal, we have conducted multiscale analysis to study the TC genesis processes, accompanied downscaling (from large-scale events) and upscaling (from small-scale events) processes, and their subsequent non-linear interactions. In this study, we first illustrate the complicated multi-scale interactions during TC genesis with our newly-developed 3D streamline packages in the NASA CAMVis system. With selected cases that include twin TCs in 2002, TC Nargis (2008) and hurricane Helene (2006), we will show that the CAMVis can provide a detailed (zoomed-in) view on hurricane physical processes and an integrative (zoomed-out) view on its interactions with environmental conditions. In the end of talk, we will discuss our future work in multiscale analysis with the Hilbert Huang Transform and improved ensemble empiric mode decomposition.

  8. A multi-channel fibre-optic link for analog telemetry

    SciTech Connect

    Shubaly, M.R.; Plato, J.G.

    1983-08-01

    Control of an ion beam injector requires a reliable telemetry link for analog signals between the high voltage dome and ground. This paper describes a selfscanning, self-checking system capable of transmitting up to sixteen channels of analog data (in each direction) with eight bit resolution over a dual light link. The technique used is serial transmission of eight bit words using standard UART's (Universal Asynchronous Receiver Transmitter) which provide much of the error detection and timing. Two versions, one stand-alone for manual control, the other an input/output interface board that plugs into a control microcomputer, have been designed. For sixteen channels, the data is updated every 3.2 milliseconds. The simple design and low parts count provide a low cost analog telemetry system.

  9. A multi-channel acoustics monitor for perioperative respiratory monitoring: preliminary data.

    PubMed

    Jafarian, Kamal; Amineslami, Majid; Hassani, Kamran; Navidbakhsh, Mahdi; Lahiji, Mohammad Niakan; Doyle, D John

    2016-02-01

    This study pertains to a six-channel acoustic monitoring system for use in patient monitoring during or after surgery. The base hardware consists of a USB data acquisition system, a custom-built six-channel amplification system, and a series of microphones of various designs. The software is based on the MATLAB platform with data acquisition drivers installed. The displayed information includes: time domain signals, frequency domain signals, and tools to aid in the detection of endobronchial intubation. We hypothesize that the above mentioned arrangement may be helpful to the anesthesiologist in recognizing clinical conditions like wheezing, bronchospasm, endobronchial intubation, and apnea. The study also evaluated various types of microphone designs used to transduce breath sounds. The system also features selectable band-pass filtering using MATLAB algorithms as well as a collection of recordings obtained with the system to establish what respiratory acoustic signals look like under various conditions. PMID:25869899

  10. A Novel Multi-Channel MAC Protocol for Cluster Based Wireless Multimedia Sensor Networks

    NASA Astrophysics Data System (ADS)

    Wei, Lu; Longmei, Zhang

    An energy efficient, scalable and collision free MAC protocol, DTFMM, is presented in this paper, which combines frequency and time division principles for medium sharing. It is based on clustered network topology, and the protocol employs a distributed local coordinate algorithm for assigning channels among clusters to enable simultaneous non-interfering data collection. Intra-cluster transmissions are scheduled by cluster head (CH) based on time slot. CHs aggregate the gathered data and forward it over inter-CH paths to the base-station based on minimum spanning tree routing. Distinct channels are adopted by the independent branches of the inter-CH routing tree. Data transmission on a branch is further scheduled in depth-first ordering. DTFMM allows nodes to stay in sleeping mode for the longest duration and thus it minimizes energy consumption. Simulation demonstrated superiority of DTFMM in terms of convergent rate, throughput and delay performance when compared with well-known protocol MMSN.

  11. Interpretation of Multi-channel X-ray Intensities from Solar Flares

    NASA Astrophysics Data System (ADS)

    Gabriel, A. H.; Bely-Dubau, F.; Millier, F.

    We investigate the analysis of muti-channel X-ray spectral intensities in terms of the electron energy distribution in the flare. This is related to the identification of thermal and non-thermal, as well as possible super-hot components. The observations studied are from SMM and from a balloon-borne instrument of Lin et al (1971). It is shown that the observations can be tilted by a wide range of different plasma conditions, making it necessary to constrain the range of models considered. This problem cannot be solved by improving the spectral resolution of the continuum channels. However, the addition of spectral line intensities from the hot plasma, as in Solar-A, is very important in reducing the ambiguity.

  12. A hazard-independent approach for the standardised multi-channel dissemination of warning messages

    NASA Astrophysics Data System (ADS)

    Esbri Palomares, M. A.; Hammitzsch, M.; Lendholt, M.

    2012-04-01

    The tsunami disaster affecting the Indian Ocean region on Christmas 2004 demonstrated very clearly the shortcomings in tsunami detection, public warning processes as well as intergovernmental warning message exchange in the Indian Ocean region. In that regard, early warning systems require that the dissemination of early warning messages has to be executed in way that ensures that the message delivery is timely; the message content is understandable, usable and accurate. To that end, diverse and multiple dissemination channels must be used to increase the chance of the messages reaching all affected persons in a hazard scenario. In addition to this, usage of internationally accepted standards for the warning dissemination such as the Common Alerting Protocol (CAP) and Emergency Data Exchange Language (EDXL) Distribution Element specified by the Organization for the Advancement of Structured Information Standards (OASIS) increase the interoperability among different warning systems enabling thus the concept of system-of-systems proposed by GEOSS. The project Distant Early Warning System (DEWS), co-funded by the European Commission under the 6th Framework Programme, aims at strengthening the early warning capacities by building an innovative generation of interoperable tsunami early warning systems based on the above mentioned concepts following a Service-oriented Architecture (SOA) approach. The project focuses on the downstream part of the hazard information processing where customized, user-tailored warning messages and alerts flow from the warning centre to the responsible authorities and/or the public with their different needs and responsibilities. The information logistics services within DEWS generate tailored EDXL-DE/CAP warning messages for each user that must receive the message according to their preferences, e.g., settings for language, interested areas, dissemination channels, etc.. However, the significant difference in the implementation and

  13. Implementation of multi-channel electronics system for astrophysical reaction studies at ORNL

    NASA Astrophysics Data System (ADS)

    Ahn, S. H.; Jones, K. L.; Matos, M.; Bardayan, D. W.; Chae, K. Y.; Smith, M. S.; Varner, R. J.; Elson, J. M.; Famiano, M. A.

    2010-11-01

    The development of large area, high-granularity silicon detector arrays has created opportunities to study transfer reactions in inverse kinematics with low-intensity radioactive beams. We are developing a new detector array comprised of 24 double-sided silicon strip detectors that will allow measurements with lower thresholds and better resolution than current detectors at ORNL. To instrument this new array, we are implementing ˜2000 channels of signal processing electronics based on application-specific integrated circuits (ASICs) designed at Washington University. The ASICs handle pulse shaping, timing, triggering, and digitization of 32 channels all on a single chip. In addition, a Real-Time Executive for Multiprocessor Systems (RTEMS) is used for a network communication between the electronics and data acquisition server. Details of the electronics setup and a status report on the devices will be presented. We will also discuss plans to utilize this system for experiments of transfer reactions using radioactive ion beams.

  14. PETA4: a multi-channel TDC/ADC ASIC for SiPM readout

    NASA Astrophysics Data System (ADS)

    Sacco, I.; Fischer, P.; Ritzert, M.

    2013-12-01

    The PETA4 ASIC is the latest member of a family of chips targeted mainly at the readout of Silicon Photomultipliers in PET, with possible use in other detector applications. PETA4 houses 36 channels on a 5 × 5mm2 die and is fabricated in the UMC 180nm technology. It uses bump bonds with a convenient pitch of ≈ 270μm to allow the construction of very compact modules at moderate substrate cost. The chip requires nearly no external components by integrating everything (PLL loop filter, bandgap reference, bias DACs,...) on chip. Power consumption is <= 40mW per channel, depending on digital speed and bias settings. Every channel has two independent frontends: an established differential amplifier which has shown to be insensitive to pickup in the target application of PET/MRI, and a single-ended frontend with very low input impedance (Zin ≈ 7Ω) for high channel count operation. A fast discriminator with tunable threshold and a noise of <= 300μV self-triggers time stamping with a bin width of 50ps as well as an integrator with programmable integration time. The amplitude signal is converted by a ≈ 9-bit SAR ADC. After conversion, events with sufficient amplitude are queued for serial readout. The previous chip version PETA3 has achieved a CRT time resolution of ≈ 200ps when reading out scintillation light from a 3 × 3×5mm3 LYSO crystal coupled at room temperature to a 3 × 3mm2 SiPM from FBK. Energy resolution for LYSO is ≈ 12.5%FWHM. LYSO crystals of 1.3mm size could be clearly identified with SiPMs of 4 × 4mm2 when using a light spreader. The architecture of PETA4 and its performance in the lab and with SiPMs will be presented.

  15. Moving beyond sequential design: Reflections on a rich multi-channel approach to data visualization.

    PubMed

    Wood, Jo; Beecham, Roger; Dykes, Jason

    2014-12-01

    We reflect on a four-year engagement with transport authorities and others involving a large dataset describing the use of a public bicycle-sharing scheme. We describe the role visualization of these data played in fostering engagement with policy makers, transport operators, the transport research community, the museum and gallery sector and the general public. We identify each of these as `channels'--evolving relationships between producers and consumers of visualization--where traditional roles of the visualization expert and domain expert are blurred. In each case, we identify the different design decisions that were required to support each of these channels and the role played by the visualization process. Using chauffeured interaction with a flexible visual analytics system we demonstrate how insight was gained by policy makers into gendered spatio-temporal cycle behaviors, how this led to further insight into workplace commuting activity, group cycling behavior and explanations for street navigation choice. We demonstrate how this supported, and was supported by, the seemingly unrelated development of narrative-driven visualization via TEDx, of the creation and the setting of an art installation and the curating of digital and physical artefacts. We assert that existing models of visualization design, of tool/technique development and of insight generation do not adequately capture the richness of parallel engagement via these multiple channels of communication. We argue that developing multiple channels in parallel opens up opportunities for visualization design and analysis by building trust and authority and supporting creativity. This rich, non-sequential approach to visualization design is likely to foster serendipity, deepen insight and increase impact. PMID:26356931

  16. The SRI24 Multi-Channel Brain Atlas: Construction and Applications.

    PubMed

    Rohlfing, Torsten; Zahr, Natalie M; Sullivan, Edith V; Pfefferbaum, Adolf

    2008-01-01

    We present a new standard atlas of the human brain based on magnetic resonance images. The atlas was generated using unbiased population registration from high-resolution images obtained by multichannel-coil acquisition at 3T in a group of 24 normal subjects. The final atlas comprises three anatomical channels (T(1)-weighted, early and late spin echo), three diffusion-related channels (fractional anisotropy, mean diffusivity, diffusion-weighted image), and three tissue probability maps (CSF, gray matter, white matter). The atlas is dynamic in that it is implicitly represented by nonrigid transformations between the 24 subject images, as well as distortion-correction alignments between the image channels in each subject. The atlas can, therefore, be generated at essentially arbitrary image resolutions and orientations (e.g., AC/PC aligned), without compounding interpolation artifacts. We demonstrate in this paper two different applications of the atlas: (a) region definition by label propagation in a fiber tracking study is enabled by the increased sharpness of our atlas compared with other available atlases, and (b) spatial normalization is enabled by its average shape property. In summary, our atlas has unique features and will be made available to the scientific community as a resource and reference system for future imaging-based studies of the human brain. PMID:19183706

  17. Performance Evaluation of Multi-Channel Wireless Mesh Networks with Embedded Systems

    PubMed Central

    Lam, Jun Huy; Lee, Sang-Gon; Tan, Whye Kit

    2012-01-01

    Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN). PMID:22368482

  18. Performance evaluation of multi-channel wireless mesh networks with embedded systems.

    PubMed

    Lam, Jun Huy; Lee, Sang-Gon; Tan, Whye Kit

    2012-01-01

    Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN). PMID:22368482

  19. Non-invasive cerebral blood volume measurement during seizures using multi-channel near infrared spectroscopic topography

    NASA Astrophysics Data System (ADS)

    Watanabe, Eiju; Maki, Atsushi; Kawaguchi, Fumio; Yamashita, Yuichi; Koizumi, Hideaki; Mayanagi, Yoshiaki

    2000-07-01

    Near infrared spectroscopic topography (NIRS) is widely recognized as a noninvasive method to measure the regional cerebral blood volume (rCBV) dynamics coupled with neuronal activities. We analyzed the rCBV change in the early phase of epileptic seizures in 12 consecutive patients with medically intractable epilepsy. Seizure was induced by bemegride injection. We used eight-channel NIRS in nine cases and 24 channel in three cases. In all of the cases, rCBV increased rapidly after the seizure onset on the focus side. The increased rCBV was observed for about 30 - 60 s. The NIRS method can be applied to monitor the rCBV change continuously during seizures. Therefore, this method may be combined with ictal SPECT as one of the most reliable noninvasive methods of focus diagnosis.

  20. A Multi-temporal MODIS Based Platform to Analyze Suspended Sediment Distribution Patterns in the Amazon River

    NASA Astrophysics Data System (ADS)

    Park, E.; Latrubesse, E. M.

    2014-12-01

    Patterns of surface sediment concentration distribution in rivers are significant for understanding the broad ranges of fluvial environmental systems. In the case of the Amazon Basin, complexity in sediment pattern distribution is affected by the anabranching channel pattern of the Amazon River, inputs from tributaries (some of which are among the largest rivers on earth) and the existence of huge and complex floodplains. This study presents a remote sensing based platform that aims to improve the understanding of the patterns of sediment distributions over the Amazon River by estimating surface sediment concentration. Field acquired surface sediment concentration data were supplied from three gauging stations representing the upstream, midstream and downstream sections of the Amazon River from 2000 to 2010 and calibrated with over 1,300 MODIS daily surface reflectance images. Robust empirical models were derived (0.63

  1. Design study for multi-channel tape recorder system, volume 1

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The means of storing multispectral, high resolution sensor data on an Earth observing satellite are studied. It is concluded that this is best done digitally on a multi-track, longitudinal, magnetic tape recorder. The machine proposed will store 8 X 10 to the 10th power bits of data on 1040 m of 51 mm-wide magnetic tape mounted on two co-planar reels.

  2. Analyzing the requirements for a robust security criteria and management of multi-level security in the clouds

    NASA Astrophysics Data System (ADS)

    Farroha, Bassam S.; Farroha, Deborah L.

    2011-06-01

    The new corporate approach to efficient processing and storage is migrating from in-house service-center services to the newly coined approach of Cloud Computing. This approach advocates thin clients and providing services by the service provider over time-shared resources. The concept is not new, however the implementation approach presents a strategic shift in the way organizations provision and manage their IT resources. The requirements on some of the data sets targeted to be run on the cloud vary depending on the data type, originator, user, and confidentiality level. Additionally, the systems that fuse such data would have to deal with the classifying the product and clearing the computing resources prior to allowing new application to be executed. This indicates that we could end up with a multi-level security system that needs to follow specific rules and can send the output to a protected network and systems in order not to have data spill or contaminated resources. The paper discusses these requirements and potential impact on the cloud architecture. Additionally, the paper discusses the unexpected advantages of the cloud framework providing a sophisticated environment for information sharing and data mining.

  3. Measurement of mode coupling distribution along a few-mode fiber using a synchronous multi-channel OTDR.

    PubMed

    Nakazawa, Masataka; Yoshida, Masato; Hirooka, Toshihiko

    2014-12-15

    We describe the nondestructive measurement of mode coupling along a few-mode fiber using a synchronous multi-channel optical time-domain reflectometer (OTDR). By installing a few-mode fiber (FMF) coupler made with a phase mask method, we excite the LP01 mode in an FMF under the test as an input mode, and then we detect backward Rayleigh scattered LP11a or LP11b modes, which were generated as a result of the mode coupling through the coupler. The mode coupling distribution between the LP01 and LP11a,b modes along the test FMF was successfully measured with a 10-m spatial resolution by obtaining the ratio between the backscattered LP01 mode and LP11a or LP11b. The value of the mode coupling obtained with the present method agreed well with that obtained with the conventional transmission method. PMID:25607078

  4. Multi-channel photon migration study in visible Chinese human muscle for optical detection of deep vein thrombosis

    NASA Astrophysics Data System (ADS)

    Sun, Yunlong; Li, Ting

    2016-03-01

    Deep vein thrombosis (DVT) always induced venous thrombosis. Most cases of venous thrombosis were induced by deep vein thrombosis (DVT), with high incidence rate of >60% in >60 years old people. Near-infrared spectroscopy (NIRS) were reported recently to be an intriguing and potential technique in detecting DVT in clinics. However, the photon transport is still unclear, which is crucial for the image reconstruction of the updated development called as NIRS-based DVT imager. Here we employed the Monte Carlo simulation software for 3D voxelized media (MCVM) and the Visible Chinese Human (VCH) model, which segmentation is finest in the world, to simulate multi-channel photon migration in calf muscle. And the image reconstruction of DVT hemodynamic distribution was achieved. This study, for the first time, provides the most realistic 3-D multichannel photon migration for NIRS study on DVT, and explored the image reconstruction for furtherly developing a NIRS-based DVT imager.

  5. Design of the multi-channel electroencephalography-based brain-computer interface with novel dry sensors.

    PubMed

    Wu, Shang-Lin; Liao, Lun-De; Liou, Chang-Hong; Chen, Shi-An; Ko, Li-Wei; Chen, Bo-Wei; Wang, Po-Sheng; Chen, Sheng-Fu; Lin, Chin-Teng

    2012-01-01

    The traditional brain-computer interface (BCI) system measures the electroencephalography (EEG) signals by the wet sensors with the conductive gel and skin preparation processes. To overcome the limitations of traditional BCI system with conventional wet sensors, a wireless and wearable multi-channel EEG-based BCI system is proposed in this study, including the wireless EEG data acquisition device, dry spring-loaded sensors, a size-adjustable soft cap. The dry spring-loaded sensors are made of metal conductors, which can measure the EEG signals without skin preparation and conductive gel. In addition, the proposed system provides a size-adjustable soft cap that can be used to fit user's head properly. Indeed, the results are shown that the proposed system can properly and effectively measure the EEG signals with the developed cap and sensors, even under movement. In words, the developed wireless and wearable BCI system is able to be used in cognitive neuroscience applications. PMID:23366259

  6. Effects of unequal electrode pairs on an x-strip thickness-shear mode multi-channel quartz crystal microbalance.

    PubMed

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-12-01

    We study the thickness-shear vibrations of an x-strip monolithic piezoelectric plate made from AT-cut quartz crystals with two unequal electrode pairs. The Tiersten-Smythe scalar differential equations for electroded and unelectroded quartz plates are separately employed, resulting in free vibration distributions and frequencies of operating modes. The vibrations of these operating modes are mainly trapped in the electroded regions. The loss of the structural symmetry can lead to a weak vibration interaction between two electroded regions. The influences of electrode difference on the vibration and frequency interference between two adjacent resonators are investigated in detail. The obtained results provide a fundamental reference to the design and optimization of multi-channel quartz crystal microbalance. PMID:27484997

  7. Reduced thermal resistance in AlGaN/GaN multi-mesa-channel high electron mobility transistors

    SciTech Connect

    Asubar, Joel T. Yatabe, Zenji; Hashizume, Tamotsu

    2014-08-04

    Dramatic reduction of thermal resistance was achieved in AlGaN/GaN Multi-Mesa-Channel (MMC) high electron mobility transistors (HEMTs) on sapphire substrates. Compared with the conventional planar device, the MMC HEMT exhibits much less negative slope of the I{sub D}-V{sub DS} curves at high V{sub DS} regime, indicating less self-heating. Using a method proposed by Menozzi and co-workers, we obtained a thermal resistance of 4.8 K-mm/W at ambient temperature of ∼350 K and power dissipation of ∼9 W/mm. This value compares well to 4.1 K-mm/W, which is the thermal resistance of AlGaN/GaN HEMTs on expensive single crystal diamond substrates and the lowest reported value in literature.

  8. Multi-Stepped Optogenetics: A Novel Strategy to Analyze Neural Network Formation and Animal Behaviors by Photo-Regulation of Local Gene Expression, Fluorescent Color and Neural Excitation

    NASA Astrophysics Data System (ADS)

    Hatta, Kohei; Nakajima, Yohei; Isoda, Erika; Itoh, Mariko; Yamamoto, Tamami

    The brain is one of the most complicated structures in nature. Zebrafish is a useful model to study development of vertebrate brain, because it is transparent at early embryonic stage and it develops rapidly outside of the body. We made a series of transgenic zebrafish expressing green-fluorescent protein related molecules, for example, Kaede and KikGR, whose green fluorescence can be irreversibly converted to red upon irradiation with ultra-violet (UV) or violet light, and Dronpa, whose green fluorescence is eliminated with strong blue light but can be reactivated upon irradiation with UV or violet-light. We have recently shown that infrared laser evoked gene operator (IR-LEGO) which causes a focused heat shock could locally induce these fluorescent proteins and the other genes. Neural cell migration and axonal pattern formation in living brain could be visualized by this technique. We also can express channel rhodopsine 2 (ChR2), a photoactivatable cation channel, or Natronomonas pharaonis halorhodopsin (NpHR), a photoactivatable chloride ion pump, locally in the nervous system by IR. Then, behaviors of these animals can be controlled by activating or silencing the local neurons by light. This novel strategy is useful in discovering neurons and circuits responsible for a wide variety of animal behaviors. We proposed to call this method ‘multi-stepped optogenetics’.

  9. Demagnetization Analysis in Excel (DAIE) - An open source workbook in Excel for viewing and analyzing demagnetization data from paleomagnetic discrete samples and u-channels

    NASA Astrophysics Data System (ADS)

    Sagnotti, Leonardo

    2013-04-01

    Modern rock magnetometers and stepwise demagnetization procedures result in the production of large datasets, which need a versatile and fast software for their display and analysis. Various software packages for paleomagnetic analyses have been recently developed to overcome the problems linked to the limited capability and the loss of operability of early codes written in obsolete computer languages and/or platforms, not compatible with modern 64 bit processors. The Demagnetization Analysis in Excel (DAIE) workbook is a new software that has been designed to make the analysis of demagnetization data easy and accessible on an application (Microsoft Excel) widely diffused and available on both the Microsoft Windows and Mac OS X operating systems. The widespread diffusion of Excel should guarantee a long term working life, since compatibility and functionality of current Excel files should be most likely maintained during the development of new processors and operating systems. DAIE is designed for viewing and analyzing stepwise demagnetization data of both discrete and u-channel samples. DAIE consists of a single file and has an open modular structure organized in 10 distinct worksheets. The standard demagnetization diagrams and various parameters of common use are shown on the same worksheet including selectable parameters and user's choices. The remanence characteristic components may be computed by principal component analysis (PCA) on a selected interval of demagnetization steps. Saving of the PCA data can be done both sample by sample, or in automatic by applying the selected choices to all the samples included in the file. The DAIE open structure allows easy personalization, development and improvement. The workbook has the following features which may be valuable for various users: - Operability in nearly all the computers and platforms; - Easy inputs of demagnetization data by "copy and paste" from ASCII files; - Easy export of computed parameters and

  10. Method for network analyzation and apparatus

    DOEpatents

    Bracht, Roger B.; Pasquale, Regina V.

    2001-01-01

    A portable network analyzer and method having multiple channel transmit and receive capability for real-time monitoring of processes which maintains phase integrity, requires low power, is adapted to provide full vector analysis, provides output frequencies of up to 62.5 MHz and provides fine sensitivity frequency resolution. The present invention includes a multi-channel means for transmitting and a multi-channel means for receiving, both in electrical communication with a software means for controlling. The means for controlling is programmed to provide a signal to a system under investigation which steps consecutively over a range of predetermined frequencies. The resulting received signal from the system provides complete time domain response information by executing a frequency transform of the magnitude and phase information acquired at each frequency step.

  11. A multi-directional and multi-scale roughness filter to detect lineament segments on digital elevation models - analyzing spatial objects in R

    NASA Astrophysics Data System (ADS)

    Baumann, Sebastian; Robl, Jörg; Wendt, Lorenz; Willingshofer, Ernst; Hilberg, Sylke

    2016-04-01

    Automated lineament analysis on remotely sensed data requires two general process steps: The identification of neighboring pixels showing high contrast and the conversion of these domains into lines. The target output is the lineaments' position, extent and orientation. We developed a lineament extraction tool programmed in R using digital elevation models as input data to generate morphological lineaments defined as follows: A morphological lineament represents a zone of high relief roughness, whose length significantly exceeds the width. As relief roughness any deviation from a flat plane, defined by a roughness threshold, is considered. In our novel approach a multi-directional and multi-scale roughness filter uses moving windows of different neighborhood sizes to identify threshold limited rough domains on digital elevation models. Surface roughness is calculated as the vertical elevation difference between the center cell and the different orientated straight lines connecting two edge cells of a neighborhood, divided by the horizontal distance of the edge cells. Thus multiple roughness values depending on the neighborhood sizes and orientations of the edge connecting lines are generated for each cell and their maximum and minimum values are extracted. Thereby negative signs of the roughness parameter represent concave relief structures as valleys, positive signs convex relief structures as ridges. A threshold defines domains of high relief roughness. These domains are thinned to a representative point pattern by a 3x3 neighborhood filter, highlighting maximum and minimum roughness peaks, and representing the center points of lineament segments. The orientation and extent of the lineament segments are calculated within the roughness domains, generating a straight line segment in the direction of least roughness differences. We tested our algorithm on digital elevation models of multiple sources and scales and compared the results visually with shaded relief map

  12. Cross talk free multi channel processing of 10 Gbit/s data via four wave mixing in a 1550 nm InAs/InP quantum dash amplifier.

    PubMed

    Capua, A; O'Duill, S; Mikhelashvili, V; Eisenstein, G; Reithmaier, J P; Somers, A; Forchel, A

    2008-11-10

    We demonstrate multi wavelength processing in a broad band 1550 nm quantum dash optical amplifier. Two 10 Gbit/s signals, spectrally separated by 30 nm are individually wavelength converted via four wave mixing (FWM) with no cross talk. High power signal levels cause depletion of high energy and wetting layer states resulting in some homogenizing of the gain medium and generation of cross FWM components near each channel due to FWM in the other channel. These do not affect the cross-talkless multichannel processing except when the two channels use equal detuning between signal and pump. PMID:19581999

  13. Sequential injection chromatography with a miniaturized multi-channel fiber optic detector for separation and quantification of propranolol and hydrochlorothiazide

    PubMed Central

    2011-01-01

    Background Sequential injection chromatography (SIC) is a new alternative separation technology. It has some advantages over high performance liquid chromatography (HPLC) regarding simplicity, inexpensiveness, portability, ease of use, maintenance requirement and operation time. In contrast, SIC has had suffered from some limitations. Results The current work involves four achievements. (a) One of the limitations of SIC has been overcome. A higher pressure resistant selection valve with additional ports was installed in an SIC system. This development allows propelling solution without showing solution leakage. (b) A new inexpensive rapid and green method for the separation and quantification of propranolol (PRP) and hydrochlorothiazide (HTZ) in their formulations was optimized and validated. (c) A miniaturized multi-channel fiber optic detector was coupled with the newly developed SIC system to detect PRP and HTZ at 270 and 290 nm, respectively. This issue enhanced the sensitivity rather than using a single-channel detector. (d) A comparative study on the efficiency of the SIC method with that of previous HPLC methods was conducted. Conclusions Besides the benefits of the instrumentation of SIC, the proposed method is rapider and more reagent-saving than previous HPLC methods. The total volume of consumed reagents and sample was 4.04 mL. The sample frequency was 22 samples/h. Other such analytical characters of the SIC method as resolution, peak symmetry, numbers of theoretical plates, linearity range, accuracy, precision and limits of detection and quantification recorded comparable results. PMID:21658210

  14. Calculation of BER in multi-channel silicon optical interconnects: comparative analysis of strip and photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    You, Jie; Lavdas, Spyros; Panoiu, Nicolae C.

    2016-05-01

    We present an effective approach to evaluate the performance of multi-channel silicon (Si) photonic systems. The system is composed of strip Si photonic waveguides (Si-PhWs) with uniform cross-section or photonic-crystal (PhC) Si waveguides (Si-PhCWs), combined with a set of direct-detection receivers. Moreover, the optical field in each channel is the superposition of a continuous-wave nonreturn-to-zero ON-OFF keying modulated signal and a white Gaussian noise. In order to characterize the optical signal propagation in the waveguides, an accurate mathematical model describing all relevant linear and nonlinear optical effects and its linearized version is employed. In addition, two semi-analytical methods, time- and frequency-domain Karhunen-Loève series expansion, are used to assess the system bit-error-rate (BER). Our analysis reveals that Si-PhCWs provide similar performance as Si-PhWs, but for 100× shorter length. Importantly, much worse BER is achieved in Si-PhCWs when one operates in slow-light regime, due to the enhanced linear and nonlinear effects.

  15. Real-time system design environment for multi-channel high-speed data acquisition system and pattern recognition

    SciTech Connect

    Crosetto, Dario B.

    1999-06-17

    The Design Real-Time 2.0 software environment provides the user with a set of tools to create a real-time fully programmable system which can sustain a rate of several MHz from multi-channel inputs, can extend processing time in a pipeline stage and can provide a result within a few hundred ns. The tool set allows the user to (a) create applications of different sizes with different throughput and filtering algorithms; (b) select the processor speed, internal bus width, lookup tables, number of input and output result bits for each set of data received at each channel for each algorithm execution; (c) simulate a specific parallel-processing system for a given algorithm on different sets of data; (d) monitor the system in real time via an RS232 interface; (e) create a hardware component (FPGA or ASIC) by means of interfacing to the Electronic Design Automation (EDA) tools. The advantage of these tools is that of allowing simulation, before construction, of an entire programmable high-speed data acquisition and processing system, and selection of the processor speed, bus width and real-time algorithm which is most cost effective for a specific application where general-purpose processors fail in speed and performance. Benefits derived from the use of the novel architecture and cost comparisons with respect to similar designs are also provided.

  16. ITQ-54: a multi-dimensional extra-large pore zeolite with 20 × 14 × 12-ring channels

    DOE PAGESBeta

    Jiang, Jiuxing; Yun, Yifeng; Zou, Xiaodong; Jorda, Jose Luis; Corma, Avelino

    2015-01-01

    A multi-dimensional extra-large pore silicogermanate zeolite, named ITQ-54, has been synthesised by in situ decomposition of the N,N-dicyclohexylisoindolinium cation into the N-cyclohexylisoindolinium cation. Its structure was solved by 3D rotation electron diffraction (RED) from crystals of ca. 1 μm in size. The structure of ITQ-54 contains straight intersecting 20 × 14 × 12-ring channels along the three crystallographic axes and it is one of the few zeolites with extra-large channels in more than one direction. ITQ-54 has a framework density of 11.1 T atoms per 1000 Å3, which is one of the lowest among the known zeolites. ITQ-54 was obtainedmore » together with GeO2 as an impurity. A heavy liquid separation method was developed and successfully applied to remove this impurity from the zeolite. ITQ-54 is stable up to 600 °C and exhibits permanent porosity. The structure was further refined using powder X-ray diffraction (PXRD) data for both as-made and calcined samples.« less

  17. ITQ-54: a multi-dimensional extra-large pore zeolite with 20 × 14 × 12-ring channels

    SciTech Connect

    Jiang, Jiuxing; Yun, Yifeng; Zou, Xiaodong; Jorda, Jose Luis; Corma, Avelino

    2015-01-01

    A multi-dimensional extra-large pore silicogermanate zeolite, named ITQ-54, has been synthesised by in situ decomposition of the N,N-dicyclohexylisoindolinium cation into the N-cyclohexylisoindolinium cation. Its structure was solved by 3D rotation electron diffraction (RED) from crystals of ca. 1 μm in size. The structure of ITQ-54 contains straight intersecting 20 × 14 × 12-ring channels along the three crystallographic axes and it is one of the few zeolites with extra-large channels in more than one direction. ITQ-54 has a framework density of 11.1 T atoms per 1000 Å3, which is one of the lowest among the known zeolites. ITQ-54 was obtained together with GeO2 as an impurity. A heavy liquid separation method was developed and successfully applied to remove this impurity from the zeolite. ITQ-54 is stable up to 600 °C and exhibits permanent porosity. The structure was further refined using powder X-ray diffraction (PXRD) data for both as-made and calcined samples.

  18. Life-threatening false alarm rejection in ICU: using the rule-based and multi-channel information fusion method.

    PubMed

    Liu, Chengyu; Zhao, Lina; Tang, Hong; Li, Qiao; Wei, Shoushui; Li, Jianqing

    2016-08-01

    False alarm (FA) rates as high as 86% have been reported in intensive care unit monitors. High FA rates decrease quality of care by slowing staff response times while increasing patient burdens and stresses. In this study, we proposed a rule-based and multi-channel information fusion method for accurately classifying the true or false alarms for five life-threatening arrhythmias: asystole (ASY), extreme bradycardia (EBR), extreme tachycardia (ETC), ventricular tachycardia (VTA) and ventricular flutter/fibrillation (VFB). The proposed method consisted of five steps: (1) signal pre-processing, (2) feature detection and validation, (3) true/false alarm determination for each channel, (4) 'real-time' true/false alarm determination and (5) 'retrospective' true/false alarm determination (if needed). Up to four signal channels, that is, two electrocardiogram signals, one arterial blood pressure and/or one photoplethysmogram signal were included in the analysis. Two events were set for the method validation: event 1 for 'real-time' and event 2 for 'retrospective' alarm classification. The results showed that 100% true positive ratio (i.e. sensitivity) on the training set were obtained for ASY, EBR, ETC and VFB types, and 94% for VTA type, accompanied by the corresponding true negative ratio (i.e. specificity) results of 93%, 81%, 78%, 85% and 50% respectively, resulting in the score values of 96.50, 90.70, 88.89, 92.31 and 64.90, as well as with a final score of 80.57 for event 1 and 79.12 for event 2. For the test set, the proposed method obtained the score of 88.73 for ASY, 77.78 for EBR, 89.92 for ETC, 67.74 for VFB and 61.04 for VTA types, with the final score of 71.68 for event 1 and 75.91 for event 2. PMID:27454710

  19. The decomposition of the Faroe-Shetland Channel water masses using Parametric Optimum Multi-Parameter analysis

    NASA Astrophysics Data System (ADS)

    McKenna, C.; Berx, B.; Austin, W. E. N.

    2016-01-01

    The Faroe-Shetland Channel (FSC) is an important conduit for the poleward flow of Atlantic water towards the Nordic Seas and, as such, it plays an integral part in the Atlantic's thermohaline circulation. Mixing processes in the FSC are thought to result in an exchange of properties between the channel's inflow and outflow, with wider implications for this circulation; the nature of this mixing in the FSC is, however, uncertain. To constrain this uncertainty, we used a novel empirical method known as Parametric Optimum Multi-Parameter (POMP) analysis to objectively quantify the distribution of water masses in the channel in May 2013. This was achieved by using a combination of temperature and salinity measurements, as well as recently available nutrient and δ18O measurements. The outcomes of POMP analysis are in good agreement with established literature and demonstrate the benefits of representing all five water masses in the FSC. In particular, our results show the recirculation of Modified North Atlantic Water in the surface layers, and the pathways of Norwegian Sea Arctic Intermediate Water and Norwegian Sea Deep Water from north to south for the first time. In a final step, we apply the mixing fractions from POMP analysis to decompose the volume transport through the FSC by water mass. Despite a number of caveats, our study suggests that improved estimates of the volume transport of Atlantic inflow towards the Arctic and, thus, the associated poleward fluxes of salt and heat are possible. A new prospect to more accurately monitor the strength of the FSC branch of the thermohaline circulation emerges from this study.

  20. Silicon Photomultiplier-Based Multi-Channel Gamma Ray Detector Using the Dynamic Time-Over-Threshold Method

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.; Shimazoe, K.; Takahashi, H.

    2016-02-01

    Silicon photomultipliers (SiPMs), which are a relatively new type of photon detector, have received more attention in the fields of nuclear medicine and high-energy physics because of their compactness and high gain up to 106. In this work, a SiPM-based multi-channel gamma ray detector with individual read out based on the dynamic time-over-threshold (dToT) method is implemented and demonstrated as an elemental material for large-area gamma ray imager applications. The detector consists of 64 channels of KETEK SiPM PM6660 (6 × 6 mm2 containing 10,000 micro-cells of 60 × 60 μm2) coupled to an 8 × 8 array of high-energy resolution Gd3(Al,Ga)5O12(Ce) (HR-GAGG) crystals (10 × 10 × 10 mm3) segmented by a 1 mm thick BaSO4 reflector. To produce a digital pulse containing linear energy information, the dToT-based read-out circuit consists of a CR-RC shaping amplifier (2.2 μs) and comparator with a feedback component. By modelling the pulse of the SiPM, the light output, and the CR-RC shaping amplifier, the integral-non-linearity (INL) was numerically calculated in terms of the delay time and the time constant of dynamic threshold movement. The experimental results of the averaged INL and energy resolution were 5.8±1.6% and the full-width-at-half-maximum (FWHM) of 7.4±0.9% at 662 keV, respectively. The 64-channel single-mode detector module was successfully implemented, demonstrating potential for its use as an elemental material for large-area gamma ray imaging applications.

  1. Spike Sorting Paradigm for Classification of Multi-channel Recorded Fasciculation Potentials

    PubMed Central

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

    2014-01-01

    Background Fasciculation potentials (FPs) are important in supporting the electrodiagnosis of Amyotrophic Lateral Sclerosis (ALS). If classified by shape, FPs can also be very informative for laboratory-based neurophysiological investigations of the motor units. Methods This study describes a Matlab program for classification of FPs recorded by multichannel surface electromyogram (EMG) electrodes. The program applies Principal Component Analysis on a set of features recorded from all channels. Then, it registers unsupervised and supervised classification algorithms to sort the FP samples. Qualitative and quantitative evaluation of the results is provided for the operator to assess the outcome. The algorithm facilitates manual interactive modification of the results. Classification accuracy can be improved progressively until the user is satisfied. The program makes no assumptions regarding the occurrence times of the action potentials, in keeping with the rather sporadic and irregular nature of FP firings. Results Ten sets of experimental data recorded from subjects with ALS using a 20-channel surface electrode array were tested. A total of 11891 FPs were detected and classified into a total of 235 prototype template waveforms. Evaluation and correction of classification outcome of such a dataset with over 6000 FPs can be achieved within 1–2 days. Facilitated interactive evaluation and modification could expedite the process of gaining accurate final results. Conclusion The developed Matlab program is an efficient toolbox for classification of FPs. PMID:25450215

  2. A multi-channel analog IC for in vitro neural recording

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Zhigong, Wang; Xiaoying, Lü

    2016-02-01

    Recent work in the field of neurophysiology has demonstrated that, by observing the firing characteristic of action potentials (AP) and the exchange pattern of signals between neurons, it is possible to reveal the nature of “memory” and “thinking” and help humans to understand how the brain works. To address these needs, we developed a prototype fully integrated circuit (IC) with micro-electrode array (MEA) for neural recording. In this scheme, the microelectrode array is composed by 64 detection electrodes and 2 reference electrodes. The proposed IC consists of 8 recording channels with an area of 5 × 5 mm2. Each channel can operate independently to process the neural signal by amplifying, filtering, etc. The chip is fabricated in 0.5-μm CMOS technology. The simulated and measured results show the system provides an effective device for recording feeble signal such as neural signals. Project supported by the National Natural Science Foundation of China (No. 61076118).

  3. Applications of Multi-Channel Safety Authentication Protocols in Wireless Networks.

    PubMed

    Chen, Young-Long; Liau, Ren-Hau; Chang, Liang-Yu

    2016-01-01

    People can use their web browser or mobile devices to access web services and applications which are built into these servers. Users have to input their identity and password to login the server. The identity and password may be appropriated by hackers when the network environment is not safe. The multiple secure authentication protocol can improve the security of the network environment. Mobile devices can be used to pass the authentication messages through Wi-Fi or 3G networks to serve as a second communication channel. The content of the message number is not considered in a multiple secure authentication protocol. The more excessive transmission of messages would be easier to collect and decode by hackers. In this paper, we propose two schemes which allow the server to validate the user and reduce the number of messages using the XOR operation. Our schemes can improve the security of the authentication protocol. The experimental results show that our proposed authentication protocols are more secure and effective. In regard to applications of second authentication communication channels for a smart access control system, identity identification and E-wallet, our proposed authentication protocols can ensure the safety of person and property, and achieve more effective security management mechanisms. PMID:26547846

  4. High speed multi-channel optical sampling technique for analog-to-digital converters

    NASA Astrophysics Data System (ADS)

    Noman, Mohammad; Donkor, Eric; Hayduk, Michael J.; Bussjager, Rebecca J.

    2005-05-01

    We describe the design and implementation of an eight channel optical sampling technique for analog-to-digital (A/D) converters. A single mode-locked laser source with a pulse reprtition rate of 250 MHz is used to generate eight highly synchronized smapling clocks each running at 500 MHz. The basic sampling circuit consistes of a reversed-biased photodiode which operates as a very fast optoelectronic switch. Actuating the photodiode ON and OFF with mode-locked laser pulses produce sampled RF signals. In the implementation of this A/D architecture, the optical clocks are delayed relative to each other using fixed passive delay lines. The time-shifted clock signals allow for sampling different phases of the input RF signal resulting in an aggregate sampling rate of 4 Gigasamples/sec (GSPS). We shall show the optical clock setup necessary in order to achieve a 4 BSPS rate. We shall also present sampling results for input RF signals with frequencies ranging from 10 to 500. Interleaving of the sampled RF output from different sampling channels will also be demonstrated.

  5. YSZ-Reinforced Alumina Multi-Channel Capillary Membranes for Micro-Filtration

    PubMed Central

    Wang, Bo; Lee, Melanie; Li, Kang

    2015-01-01

    The combined phase-inversion and sintering method not only produces ceramic hollow fibre membranes with much lower fabrication costs than conventional methods, but these membranes can also be designed to have greatly reduced transport resistances for filtration processes. The bottleneck of this technique is the weak mechanical property of the fibres, due to the small dimensions and the brittle nature of the ceramic materials. In this study, yttrium stabilised zirconia (YSZ) reinforced alumina seven-channel capillary microfiltration membranes were prepared with a pore size of ~230 nm and their mechanical property and permeation characteristics were studied. It is found that the addition of YSZ can effectively enhance the mechanical property of the membrane and also increase pure water permeation flux. The Al2O3-YSZ seven-channel capillary membranes could reach a fracture load of 23.4 N and a bending extension of 0.54 mm when being tested with a 6 cm span, to meet the requirements for most industrial microfiltration applications. PMID:26729178

  6. Comparison of Channel Methods and Observer Models for the Task-Based Assessment of Multi-Projection Imaging in the Presence of Structured Anatomical Noise.

    PubMed

    Park, Subok; Zhang, George; Myers, Kyle J

    2016-06-01

    Although Laguerre-Gauss (LG) channels are often used for the task-based assessment of multi-projection imaging, LG channels may not be the most reliable in providing performance trends as a function of system or object parameters for all situations. Partial least squares (PLS) channels are more flexible in adapting to background and signal data statistics and were shown to be more efficient for detection tasks involving 2D non-Gaussian random backgrounds (Witten , 2010). In this work, we investigate ways of incorporating spatial correlations in the multi-projection data space using 2D LG channels and two implementations of PLS in the channelized version of the 3D projection Hotelling observer (Park , 2010) (3Dp CHO). Our task is to detect spherical and elliptical 3D signals in the angular projections of a structured breast phantom ensemble. The single PLS (sPLS) incorporates the spatial correlation within each projection, whereas the combined PLS (cPLS) incorporates the spatial correlations both within each of and across the projections. The 3Dp CHO-R indirectly incorporates the spatial correlation from the response space (R), whereas the 3Dp CHO-C from the channel space (C). The 3Dp CHO-R-sPLS has potential to be a good surrogate observer when either sample size is small or one training set is used for training both PLS channels and observer. So does the 3Dp CHO-C-cPLS when the sample size is large enough to have a good sized independent set for training PLS channels. Lastly a stack of 2D LG channels used as 3D channels in the CHO-C model showed the capability of incorporating the spatial correlation between the multiple angular projections. PMID:26742128

  7. Widefield TSCSPC-systems with large-area-detectors: application in simultaneous multi-channel-FLIM

    NASA Astrophysics Data System (ADS)

    Stepanov, Sergei; Bakhlanov, Sergei; Drobchenko, Evgeny; Eckert, Hann-Jörg; Kemnitz, Klaus

    2010-11-01

    Novel proximity-type Time- and Space-Correlated Single Photon Counting (TSCSPC) crossed-delay-line (DL)- and multi-anode (MA)-systems of outstanding performance and homogeneity were developed, using large-area detector heads of 25 and 40 mm diameter. Instrument response functions IRF(space) = (60 +/- 5) μm FWHM and IRF(time) = (28 +/- 3) ps FWHM were achieved over the full 12 cm2 area of the detector. Deadtime at throughput of 105 cps is 10% for "high-resolution" system and 5% in the "video"-system at 106 cps, at slightly reduced time- and space resolution. A fluorescence lifetime of (3.5 +/- 1) ps can be recovered from multi-exponential dynamics of a single living cyanobacterium (Acaryochloris marina). The present large-area detectors are particularly useful in simultaneous multichannel applications, such as 2-colour anisotropy or 4-colour lifetime imaging, utilizing dual- or quad-view image splitters. The long-term stability, low- excitation-intensity (< 100 mW/cm2) widefield systems enable minimal-invasive observation, without significant bleaching or photodynamic reactions, thus allowing long-period observation of up to several hours in living cells.

  8. Studying and analyzing the formation and dynamics of the black cloud over Cairo, Egypt, using a multi sensor approach

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Prasad, A. K.; Marey, H. M.; El-Raey, M. E.; Asrar, G. R.; Kafatos, M.

    2012-04-01

    In the past decade, episodes of severe air pollution from biomass burning and/or industrial activities, known as the "black cloud" have occurred over Cairo, and the Nile Delta region situated on the eastern side of the Sahara desert in Egypt, during the autumn season. Previous studies have attributed the increased pollution levels during the black cloud season only to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. It was found that the same region receives as well numerous dust storms along with the anthropogenic aerosols during same season. Such complex combination of these aerosols results in poor air quality and poses significant health hazards for the population in this region. In this study, data from the Moderate Resolution Imaging Spectrometer (MODIS) along with the Multiangle Imaging Spectroradiometer (MISR) are used with meteorological data and trajectory analyses to determine the cause of these events. MODIS fire counts highlighted the anthropogenic component of the dense cloud resulting from the burning of agricultural waste after harvest season. Synchronous MISR data show that these fires create low altitude (<500 m) plumes of smoke and aerosols which flow over Cairo in a few hours, as confirmed by Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) forward trajectory analysis. Much of the burning occurs at night, when a thermal inversion constrains the plumes to remain in the boundary layer (BL). Convection during the day raises the BL, dispersing these smoke particles until the next night. However, we have found a dust transport pathway along the Mauritania/Mali/Algeria/Libya/Egypt axis that significantly affects NE Africa, especially the Nile Delta region, during the biomass burning season

  9. Analyzing the effects of historical and recent floods on channel pattern and the environment in the Lower Omo basin of Ethiopia using satellite images and GIS

    NASA Astrophysics Data System (ADS)

    Ayalew, Lulseged

    2009-10-01

    Previous accounts and recent observations indicate that the pattern and geometry of the Omo River meanders in the Lower Omo basin of Ethiopia had already been established in earlier times by large floods that took place after extended periods of drought. The cross-sectional changes resulted from floods in the nineteenth and twentieth centuries, were then simply limited to small degree channel widening and entrenchment, and floodplain erosion and deposition. The effects of the August 2006 flood, although widespread and destructive for the environment, were also modest as far as adjusting the channel pattern is concerned. Changes in channel profiles at short-term scales usually come in the form of aggradation and degradation. Interpretations of satellite images taken before and after the flood showed the accumulation of coarse sediments in the channel. There are also some sporadic indications for an increase in channel width. Widening in response to high amount of discharges can generally be expected during floods. Besides, signs of channel shortening were observed in some places. Apart from these minor changes, the dimension of meandering segments or the outline of the entire meander belt, and the basic morphology of the channel remained unaffected.

  10. A floating multi-channel picoammeter for micropattern gaseous detector current monitoring

    NASA Astrophysics Data System (ADS)

    Utrobicic, A.; Kovacic, M.; Erhardt, F.; Poljak, N.; Planinic, M.

    2015-11-01

    This paper presents a concept of a multiple channel picoammeter suitable for operation at a high voltage. To ensure floating operation, 1 kHz readout rate and low battery usage, the picoammeter employs an optical fibre for data transmission. The analogue conditioning section consists of a transimpedance amplifier that is connected to a 16 bit ΣΔ ADC which is integrated into the microcontroller. Simultaneous reception of data sent from multiple picoammeter units is achieved using an FPGA device and a USB interface to the host PC. A prototype with a ± 125 nA range was constructed. The paper includes a calibration procedure of the prototype and an example of a current leakage test conducted on a 10×10 cm2 GEM foil. The resolution achieved by the prototype in a 15 min test at 0.5 nA bias was 6.5 pA FWHM.

  11. Multi-channel LED light source for fluorescent agent aided minimally invasive surgery.

    PubMed

    Ren, Jiacheng; Venugopalan, Janani; Xu, Jian; Kairdolf, Brad; Durfee, Robert; Wang, May D

    2014-01-01

    Cancer is one of the most common and deadly diseases around the world. Amongst all the different treatments of cancer such as surgery, chemotherapy and radiation therapy, surgical resection is the most effective. Successful surgeries greatly rely on the detection of the accurate tumor size and location, which can be enhanced by contrast agents. Commercial endoscope light sources, however, offer only white light illumination. In this paper, we present the development of a LED endoscope light source that provides 2 light channels plus white light to help surgeons to detect a clear tumor margin during minimally invasive surgeries. By exciting indocyanine green (ICG) and 5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX), the light source is intended to give the user a visible image of the tumor margin. This light source is also portable, easy to use and costs less than $300 to build. PMID:25571589

  12. Multi-Channel LED Light Source for Fluorescent Agent Aided Minimally Invasive Surgery

    PubMed Central

    Ren, Jiacheng; Venugopalan, Janani; Xu, Jian; Kairdolf, Brad; Durfee, Robert; Wang, May D.

    2016-01-01

    Cancer is one of the most common and deadly diseases around the world. Amongst all the different treatments of cancer such as surgery, chemotherapy and radiation therapy, surgical resection is the most effective. Successful surgeries greatly rely on the detection of the accurate tumor size and location, which can be enhanced by contrast agents. Commercial endoscope light sources, however, offer only white light illumination. In this paper, we present the development of a LED endoscope light source that provides 2 light channels plus white light to help surgeons to detect a clear tumor margin during minimally invasive surgeries. By exciting indocyanine green (ICG) and 5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX), the light source is intended to give the user a visible image of the tumor margin. This light source is also portable, easy to use and costs less than $300 to build. PMID:25571589

  13. Studies on Physical Properties of Snow Based on Multi Channel Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Tsuchiya, K.; Takeda, K.

    1985-01-01

    The analysis of the data observed over a snow field with a breadboard model of MSR (microwave scanning radiometer) to be installed in MOS-1 (Marine Observation Satellite-1) indicates that: (1) the influence of incident angle on brightness temperature is larger in horizontal polarization component than in vertical polarization component. The effect of incident angle depends upon the property of snow with larger value for dry snow; (2) the difference of snow surface configuration consisting of artifically made parallel ditches of 5 cm depth and 5 cm width with spacing of 10 and 30 cm respectively which are oriented normal to electrical axis do not affect brightness temperature significantly; and (3) there is high negative correlation between brightness temperature and snow depth up to the depth of 70 cm which suggests that the snow depth can be measured with a two channel microwave radiometer up to this depth.

  14. A method for stable electrical connection of a multi-channeled polyimide electrode with PCB.

    PubMed

    Baek, Dong-Hyun; Jung, Ha-Chul; Kim, Seon Min; Im, Chang-Hwan; Pak, James Jungho; Lee, Sang-Hoon

    2012-01-01

    We propose a novel packaging method of a thin polyimide multichannel microelectrode. For the simple electrical connection of polyimide (PI) electrodes, we made a via-hole at the interconnection pads of thin PI electrodes, and constructed a Ni ring by electroplating through the via-hole for the stable soldering and strong adhesion of the electrode to PCB. For the construction of a well-organized Ni ring, the electroplating condition was optimized, and the electrical property of the packaged electrode was evaluated. A 40 channel thin PI electrode was fabricated and packaged by the proposed method, and we performed the animal experiment with this packaged electrode for the high-resolution recording of neural signals from the skull of a rat. PMID:23366923

  15. Multi-phase submarine channel-fill history recorded by stratigraphic architectures in outcropping slope-channel deposits, Tres Pasos Formation, southern Chile

    NASA Astrophysics Data System (ADS)

    Auchter, N.; Romans, B.; Hubbard, S. M.; Daniels, B. G.; Reimchen, A. P.; Jackson, A. A.; Stright, L.

    2014-12-01

    The relationship between sediment transport processes, deposits, and channel morphology is well established for subaerial channel systems. Linking channel-fill patterns with planform morphology in submarine systems, however, is less constrained because of the difficulty in direct observation of sediment transport processes, including deposition of coarse-grained turbidites. Ever-increasing resolution of 3-D seismic-reflection and integrated bathymetry-sonar tools have led to significant improvement, but resolution issues still hinder effective analysis. For example, are inclined reflectors observed in seismic cross sections of channels associated with sinuous planforms indicative of turbidity-current-scale morphodynamics or are they composite surfaces that record larger-scale/longer-term evolution? Documenting the nature and variability of intra-channel fill architecture in outcropping submarine channel deposits provides insight into linking depositional processes and channel morphologies. The Late Cretaceous retroarc foreland Magallanes Basin in southern Chile formed during uplift of the Andean Cordillera. Deep-water slope strata of the Tres Pasos Formation are exposed along a depositional-dip-oriented outcrop belt up to 2000 m thick and at least 100 km long. These strata provide an excellent natural laboratory for comparison of slope channel architectures from different positions on the slope and stages of basin infilling. We consider channelized architectural element dimensions and internal stratigraphic surface characteristics from multiple exposures along the outcrop belt. We also document varying stacking patterns of channel elements over time, from both laterally to vertically offset end-members. Results suggest that for both lateral and vertical channel stacking patterns, phases of accommodation generation (e.g., incision or sediment bypass) and migration of the channel are temporally distinct from phases of channel infilling (e.g., turbidity current

  16. Utilizing Multi-Sensor Data Products and high-resolution flood model in Analyzing North African Hydrological Processes

    NASA Astrophysics Data System (ADS)

    Thengumthara, K.; Policelli, F.; Habib, S.; David, J. L.; Melocik, K. A.; Huffman, G. J.; Anderson, M. C.; Ali, A. B.; Bacha, S.

    2013-12-01

    North Africa is an arid region characterized by isolated extreme events such as floods and droughts. Our present understanding of hydrological processes over North Africa is limited due to low rainfall, mixed response of evaporation to temperature and soil moisture gradients, and lack of high-resolution ground measurements. Remote sensing is an excellent way to obtain near real- time data of high spatial and temporal resolution. Satellite estimates of rainfall and evapotranspiration (ET) have uncertainties due to topography, land-sea contrast, complex weather, and climate variability for high-elevated regions. Generally for arid regions, the satellite precipitation instruments are sensitive to soil moisture and land surface geometry. This study analyzes different components of hydrological processes over North Africa based on remote sensing data such as precipitation (NASA-TMPA, CMORPH and PERSIANN), evaporation (ALEXI and MODIS), and elevation (SRTM) along with ground measurements and model simulations. Here we use the Coupled Routing and Excess STorage (CREST) hydrological model-version 2.0, which was originally developed by NASA-GSFC and the University of Oklahoma [Wang J et al., 2011]. The model is driven by real time TMPA and climatological PET, interpolated to model grids. The flexible simulation and calibration enables the model to provide high-resolution runoff and water depth at each time step. Our study mainly focuses on two major basins such as Medjerda over Tunisia and the Sebou basin of Morocco. Case studies of flood events over North Africa were analyzed based on CREST model simulations with respect to ground measurements. The floods are mainly modulated by rainfall associated with synoptic frontal and tropical plumes and orographic mesoscale systems. Occurrences of peak floods simulated by CREST are comparable with diagnostics such as vertically integrated moisture convergence, stratiform and convective precipitation from ECMWF reanalysis. These were

  17. Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor

    NASA Astrophysics Data System (ADS)

    Gupta, Prasoon; Horrom, Travis; Anderson, Brian E.; Glasser, Ryan; Lett, Paul D.

    2016-02-01

    Four-wave mixing in atomic vapor allows for the generation of multi-spatial-mode states of light containing many pairs of two-mode entangled vacuum beams. This in principle can be used to send independent secure keys to multiple parties simultaneously using a single light source. In our experiment, we demonstrate this spatial multiplexing of information by selecting three independent pairs of entangled modes and performing continuous-variable measurements to verify the correlations between entangled partners. In this way, we generate three independent pairs of correlated random bit streams that could be used as secure keys. We then demonstrate a classical four-party secret sharing scheme as an example for how this spatially multiplexed source could be used.

  18. #Learning: The use of back channel technology in multi-campus nursing education.

    PubMed

    Yates, Karen; Birks, Melanie; Woods, Cindy; Hitchins, Marnie

    2015-09-01

    This paper reports on the results of a study into the use of microblogging technology (TodaysMeet) in large, multi-site lectures in a nursing program. The aim of this study was to investigate students' use of the technology and their perceptions of its value in stimulating engagement in a complex learning environment. The study demonstrated that students like the anonymity that the technology provided, allowing them to ask questions without fear of appearing less competent than their peers. Many of the respondents commented positively on the opportunity to engage with students and the lecturer at other campuses. While some students appreciated the opportunity to interact and have feedback from peers, others saw this as a negative aspect of the technology. This study suggests that, used appropriately, microblogging can be incorporated into large lectures to promote student participation and engagement and ultimately enhance the learning process. PMID:26159816

  19. Digital multi-channel stabilization of four-mode phase-sensitive parametric multicasting.

    PubMed

    Liu, Lan; Tong, Zhi; Wiberg, Andreas O J; Kuo, Bill P P; Myslivets, Evgeny; Alic, Nikola; Radic, Stojan

    2014-07-28

    Stable four-mode phase-sensitive (4MPS) process was investigated as a means to enhance two-pump driven parametric multicasting conversion efficiency (CE) and signal to noise ratio (SNR). Instability of multi-beam, phase sensitive (PS) device that inherently behaves as an interferometer, with output subject to ambient induced fluctuations, was addressed theoretically and experimentally. A new stabilization technique that controls phases of three input waves of the 4MPS multicaster and maximizes CE was developed and described. Stabilization relies on digital phase-locked loop (DPLL) specifically was developed to control pump phases to guarantee stable 4MPS operation that is independent of environmental fluctuations. The technique also controls a single (signal) input phase to optimize the PS-induced improvement of the CE and SNR. The new, continuous-operation DPLL has allowed for fully stabilized PS parametric broadband multicasting, demonstrating CE improvement over 20 signal copies in excess of 10 dB. PMID:25089457

  20. The Use of Continuous Wavelet Transform Based on the Fast Fourier Transform in the Analysis of Multi-channel Electrogastrography Recordings.

    PubMed

    Komorowski, Dariusz; Pietraszek, Stanislaw

    2016-01-01

    This paper presents the analysis of multi-channel electrogastrographic (EGG) signals using the continuous wavelet transform based on the fast Fourier transform (CWTFT). The EGG analysis was based on the determination of the several signal parameters such as dominant frequency (DF), dominant power (DP) and index of normogastria (NI). The use of continuous wavelet transform (CWT) allows for better visible localization of the frequency components in the analyzed signals, than commonly used short-time Fourier transform (STFT). Such an analysis is possible by means of a variable width window, which corresponds to the scale time of observation (analysis). Wavelet analysis allows using long time windows when we need more precise low-frequency information, and shorter when we need high frequency information. Since the classic CWT transform requires considerable computing power and time, especially while applying it to the analysis of long signals, the authors used the CWT analysis based on the fast Fourier transform (FFT). The CWT was obtained using properties of the circular convolution to improve the speed of calculation. This method allows to obtain results for relatively long records of EGG in a fairly short time, much faster than using the classical methods based on running spectrum analysis (RSA). In this study authors indicate the possibility of a parametric analysis of EGG signals using continuous wavelet transform which is the completely new solution. The results obtained with the described method are shown in the example of an analysis of four-channel EGG recordings, performed for a non-caloric meal. PMID:26573647

  1. The multi-channel cochlear implant: multi-disciplinary development of electrical stimulation of the cochlea and the resulting clinical benefit.

    PubMed

    Clark, Graeme M

    2015-04-01

    This multi-disciplinary research showed sound could be coded by electrical stimulation of the cochlea and peripheral auditory nervous system. But the temporal coding of frequency as seen in the experimental animal, was inadequate for the important speech frequencies. The data indicated the limitation was due in particular to deterministic firing of neurons and failure to reproduce the normal fine temporo-spatial pattern of neural responses seen with sound. However, the data also showed the need for the place coding of frequency, and this meant multi-electrodes inserted into the cochlea. Nevertheless, before this was evaluated on people we undertook biological safety studies to determine the effects of surgical trauma and electrical stimuli, and how to prevent infection. Then our research demonstrated place of stimulation had timbre and was perceived as vowels. This led to our discovery in 1978 of the formant-extraction speech code that first enabled severely-profoundly deaf people to understand running speech. This result in people who had hearing before becoming severely deaf was an outcome not previously considered possible. In 1985 it was the first multi-channel implant to be approved by the US Food and Drug Administration (FDA). It was also the fore runner of our advanced formant and fixed filter strategies When these codes were used from 1985 for those born deaf or deafened early in life we discovered there was a critical period when brain plasticity would allow speech perception and language to be developed near- normally, and this required in particular the acquisition of place coding. In 1990 this led to the first cochlear implant to be approved by the FDA for use in children. Finally, we achieved binaural hearing in 1989 with bilateral cochlear implants, followed by bimodal speech processing in 1990 with a hearing aid in one ear and implant in the other. The above research has been developed industrially, with for example 250,000 people worldwide receiving

  2. Operational experience with a long-range, multi-channel acoustic telemetry system

    SciTech Connect

    High, G.; Carman, R.J.

    1985-01-01

    This paper describes the design, installation, and long-term operation of a modular subsea acoustic data acquisition system in the Duncan/Argyll field, North Sea. This equipment is presently providing on-demand pressure data from eight satellite locations at ranges in excess of seven kilometres. The discussion covers the use of in-field noise measurements for optimizing system performance in a high noise environment. Two main sections cover firstly platform installation and seabed installation of the subsea transceiver. Secondly at the remote wellhead locations, the acoustic transponders are described. Cost factors, as compared with hardwired or diver-monitored data acquisition systems are discussed. Modular design permits convenient addition of other data channels and/or extra remote subsea units. The surface equipment installed at the platform is software controlled so that display and data logging can be configured according to operator needs. Variations of the same basis system are discussed, as currently in use for subsea pipeline valve actuation, and submersible flowline tow-out instrumentation. Results of several years of operational experience in various offshore applications give confidence that, when properly considered in system design, an acoustic telemetry system can function reliably at useful ranges in the offshore environment.

  3. Diagnosis of schistosomiasis japonica with interfacial co-assembly-based multi-channel electrochemical immunosensor arrays

    NASA Astrophysics Data System (ADS)

    Deng, Wangping; Xu, Bin; Hu, Haiyan; Li, Jianyong; Hu, Wei; Song, Shiping; Feng, Zheng; Fan, Chunhai

    2013-05-01

    Schistosomiasis control remains to be an important and challenging task in the world. However, lack of quick, simple, sensitive and specific sero-diagnostic test is still a hurdle in the control practice. The commonly employed enzyme-linked immuno-sorbent assay (ELISA) relies on the native soluble egg antigen (SEA) that is limited in supply. Here we developed an electrochemical immunosensor array (ECISA) assay with an interfacial co-assembly strategy. A recombinant Schistosoma japonicum (Sj) calcium-binding protein (SjE16) was used as a principal antigen, while the SEA as a minor, co-assembling agent, with a ratio of 8:1 (SjE16: SEA, Sj16EA), which was co-immobilized on a disposable 16-channel screen-printed carbon electrode array. A portable electrochemical detector was employed to detect antibodies in serum samples. The sensitivity of ECISA reached 100% with minimal cross-reactions. Therefore, we have demonstrated that this rapid, sensitive and specific ECISA technique has the potential to perform large-scale on-site screening of Sj infection.

  4. Multi-Channel Microstrip Transceiver Arrays Using Harmonics for High Field MR Imaging in Humans

    PubMed Central

    Wu, Bing; Wang, Chunsheng; Lu, Jonathan; Pang, Yong; Nelson, Sarah J; Vigneron, Daniel B; Zhang, Xiaoliang

    2012-01-01

    RF transceiver array design using primary and higher order harmonics for in-vivo parallel MR imaging and spectroscopic imaging is proposed. The improved electromagnetic decoupling performance, unique magnetic field distributions and high-frequency operation capabilities of higher-order harmonics of resonators would benefit transceiver arrays for parallel MRI, especially for ultrahigh field parallel MRI. To demonstrate this technique, microstrip transceiver arrays using first and second harmonic resonators were developed for human head parallel imaging at 7T. Phantom and human head images were acquired and evaluated using the GRAPPA reconstruction algorithm. The higher-order harmonic transceiver array design technique was also assessed numerically using FDTD simulation. Compared with regular primary-resonance transceiver designs, the proposed higher-order harmonic technique provided an improved g-factor and increased decoupling among resonant elements without using dedicated decoupling circuits, which would potentially lead to a better parallel imaging performance and ultimately faster and higher quality imaging. The proposed technique is particularly suitable for densely spaced transceiver array design where the increased mutual inductance among the elements becomes problematic. In addition, it also provides a simple approach to readily upgrade the channels of a conventional primary resonator microstrip array to a larger number for faster imaging. PMID:21878410

  5. Multi-channel MRI segmentation with graph cuts using spectral gradient and multidimensional Gaussian mixture model

    NASA Astrophysics Data System (ADS)

    Lecoeur, Jérémy; Ferré, Jean-Christophe; Collins, D. Louis; Morrisey, Sean P.; Barillot, Christian

    2009-02-01

    A new segmentation framework is presented taking advantage of multimodal image signature of the different brain tissues (healthy and/or pathological). This is achieved by merging three different modalities of gray-level MRI sequences into a single RGB-like MRI, hence creating a unique 3-dimensional signature for each tissue by utilising the complementary information of each MRI sequence. Using the scale-space spectral gradient operator, we can obtain a spatial gradient robust to intensity inhomogeneity. Even though it is based on psycho-visual color theory, it can be very efficiently applied to the RGB colored images. More over, it is not influenced by the channel assigment of each MRI. Its optimisation by the graph cuts paradigm provides a powerful and accurate tool to segment either healthy or pathological tissues in a short time (average time about ninety seconds for a brain-tissues classification). As it is a semi-automatic method, we run experiments to quantify the amount of seeds needed to perform a correct segmentation (dice similarity score above 0.85). Depending on the different sets of MRI sequences used, this amount of seeds (expressed as a relative number in pourcentage of the number of voxels of the ground truth) is between 6 to 16%. We tested this algorithm on brainweb for validation purpose (healthy tissue classification and MS lesions segmentation) and also on clinical data for tumours and MS lesions dectection and tissues classification.

  6. Metallic contaminant detection system using multi-channel high Tc SQUIDs

    NASA Astrophysics Data System (ADS)

    Tanaka, Saburo; Kitamura, Yoshihiro; Hatsukade, Yoshimi; Ohtani, Takeyoshi; Suzuki, Shuichi

    2012-10-01

    We have developed the magnetic metallic contaminant detectors using multiple high Tc SQUID gradiometers for industrial products. Finding ultra-small metallic contaminants is a big issue for manufacturers producing commercial products. The quality of industrial products such as lithium ion batteries can deteriorate by the inclusion of tiny metallic contaminants. When the contamination does occur, the manufacturer of the product suffers a great loss to recall the tainted products. Metallic particles with outer dimension less than 50 μm cannot be detected by a conventional X-ray imaging. Therefore a high sensitive detection system for small foreign matters is required. However, in most of the cases, the matrix of an active material coated sheet electrode is magnetized and the magnetic signal from the matrix is large enough to mask the signal from contaminants. Thus we have developed a detection system based on a SQUID gradiometer and a horizontal magnetization to date. For practical use, we should increase the detection width of the system by employing multiple sensors. We successfully realized an eight-channel high-Tc SQUID gradiometer system for inspection of sheet electrodes of a lithium ion battery with width of at least 60 to 70 mm. Eight planar SQUID gradiometers were mounted with a separation of 9.0 mm. As a result, small iron particles of less than 50 μm were successfully measured. This result suggests that the system is a promising tool for the detection of contaminants in a lithium ion battery.

  7. High-Speed, Multi-Channel Serial ADC LVDS Interface for Xilinx Virtex-5 FPGA

    NASA Technical Reports Server (NTRS)

    Taylor, Gregory H.

    2012-01-01

    Analog-to-digital converters (ADCs) are used in scientific and communications instruments on all spacecraft. As data rates get higher, and as the transition is made from parallel ADC designs to high-speed, serial, low-voltage differential signaling (LVDS) designs, the need will arise to interface these in field programmable gate arrays (FPGAs). As Xilinx has released the radiation-hardened version of the Virtex-5, this will likely be used in future missions. High-speed serial ADCs send data at very high rates. A de-serializer instantiated in the fabric of the FPGA could not keep up with these high data rates. The Virtex-5 contains primitives designed specifically for high-speed, source-synchronous de-serialization, but as supported by Xilinx, can only support bitwidths of 10. Supporting bit-widths of 12 or more requires the use of the primitives in an undocumented configuration, a non-trivial task. A new SystemVerilog design was written that is simpler and uses fewer hardware resources than the reference design described in Xilinx Application Note XAPP866. It has been shown to work in a Xilinx XC5VSX24OT connected to a MAXIM MAX1438 12-bit ADC using a 50-MHz sample clock. The design can be replicated in the FPGA for multiple ADCs (four instantiations were used for a total of 28 channels).

  8. Diagnosis of schistosomiasis japonica with interfacial co-assembly-based multi-channel electrochemical immunosensor arrays.

    PubMed

    Deng, Wangping; Xu, Bin; Hu, Haiyan; Li, Jianyong; Hu, Wei; Song, Shiping; Feng, Zheng; Fan, Chunhai

    2013-01-01

    Schistosomiasis control remains to be an important and challenging task in the world. However, lack of quick, simple, sensitive and specific sero-diagnostic test is still a hurdle in the control practice. The commonly employed enzyme-linked immuno-sorbent assay (ELISA) relies on the native soluble egg antigen (SEA) that is limited in supply. Here we developed an electrochemical immunosensor array (ECISA) assay with an interfacial co-assembly strategy. A recombinant Schistosoma japonicum (Sj) calcium-binding protein (SjE16) was used as a principal antigen, while the SEA as a minor, co-assembling agent, with a ratio of 8:1 (SjE16: SEA, Sj16EA), which was co-immobilized on a disposable 16-channel screen-printed carbon electrode array. A portable electrochemical detector was employed to detect antibodies in serum samples. The sensitivity of ECISA reached 100% with minimal cross-reactions. Therefore, we have demonstrated that this rapid, sensitive and specific ECISA technique has the potential to perform large-scale on-site screening of Sj infection. PMID:23648995

  9. Design and fabrication of multi-channel photodetector array monolithic with arrayed waveguide grating

    NASA Astrophysics Data System (ADS)

    Qian-Qian, Lv; Pan, Pan; Han, Ye; Dong-Dong, Yin; Yu-Bing, Wang; Xiao-Hong, Yang; Qin, Han

    2016-03-01

    We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13-channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refractive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickness of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick matching layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W. Project supported by the National High Technology Research and Development Program of China (Grant Nos. 2013AA031401, 2015AA016902, and 2015AA016904), the National Natural Science Foundation of China (Grant Nos. 61176053, 61274069, and 61435002), and the National Basic Research Program of China (Grant Nos. 2012CB933503 and 2013CB932904).

  10. Ion channel regulation by phosphoinositides analyzed with VSPs—PI(4,5)P2 affinity, phosphoinositide selectivity, and PI(4,5)P2 pool accessibility

    PubMed Central

    Rjasanow, Alexandra; Leitner, Michael G.; Thallmair, Veronika; Halaszovich, Christian R.; Oliver, Dominik

    2015-01-01

    The activity of many proteins depends on the phosphoinositide (PI) content of the membrane. E.g., dynamic changes of the concentration of PI(4,5)P2 are cellular signals that regulate ion channels. The susceptibility of a channel to such dynamics depends on its affinity for PI(4,5)P2. Yet, measuring affinities for endogenous PIs has not been possible directly, but has relied largely on the response to soluble analogs, which may not quantitatively reflect binding to native lipids. Voltage-sensitive phosphatases (VSPs) turn over PI(4,5)P2 to PI(4)P when activated by depolarization. In combination with voltage-clamp electrophysiology VSPs are useful tools for rapid and reversible depletion of PI(4,5)P2. Because cellular PI(4,5)P2 is resynthesized rapidly, steady state PI(4,5)P2 changes with the degree of VSP activation and thus depends on membrane potential. Here we show that titration of endogenous PI(4,5)P2 with Ci-VSP allows for the quantification of relative PI(4,5)P2 affinities of ion channels. The sensitivity of inward rectifier and voltage-gated K+ channels to Ci-VSP allowed for comparison of PI(4,5)P2 affinities within and across channel subfamilies and detected changes of affinity in mutant channels. The results also reveal that VSPs are useful only for PI effectors with high binding specificity among PI isoforms, because PI(4,5)P2 depletion occurs at constant overall PI level. Thus, Kir6.2, a channel activated by PI(4,5)P2 and PI(4)P was insensitive to VSP. Surprisingly, despite comparable PI(4,5)P2 affinity as determined by Ci-VSP, the Kv7 and Kir channel families strongly differed in their sensitivity to receptor-mediated depletion of PI(4,5)P2. While Kv7 members were highly sensitive to activation of PLC by Gq-coupled receptors, Kir channels were insensitive even when PI(4,5)P2 affinity was lowered by mutation. We hypothesize that different channels may be associated with distinct pools of PI(4,5)P2 that differ in their accessibility to PLC and VSPs. PMID

  11. Pockmarks, fluid flow, and sediments outboard of the deformation front at the Cascadia Subduction Zone from analysis of multi-channel seismic and multi-beam sonar data

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Carbotte, S. M.; Han, S.; Carton, H. D.; Canales, P.; Nedimovic, M. R.

    2013-12-01

    Evidence of active fluid flow and the nature of the sediment section near the Cascadia deformation front are explored using multi-channel (MCS) seismic and multi-beam sonar data collected in summer 2012 using the R/V Marcus G. Langseth during the Juan de Fuca Ridge to Trench Survey. The MCS data were collected along two full plate transects (the 'Oregon' and 'Washington' transects) and one trench parallel line using a 6600 cubic inch source, and an 8 km streamer with 636 channels (12.5 m spacing). The MCS data pre-stack processing sequence includes geometry definition, trace editing, F-K filter, and deconvolution. Velocity analysis is performed via semblance and constant velocity stacks in order to create a velocity model of the sediments and upper oceanic crust. The traces are then stacked, and post-stack time migrated. The sonar data were collected using the R/V Langseth's Kongsberg EM122 1°x1° multi-beam sonar with 288 beams and 432 total soundings across track. Using MB-system the sonar data are cleaned, and the bathymetry data are then gridded at 35 m, while the backscatter data are gridded at 15 m. From the high-resolution mapping data 48 pockmarks varying in diameter from 50 m - 1 km are identified within 60 km outboard of the deformation front. The surface expression of these large features in an area of heavy sedimentation is likely indicative of active fluid flow. In order to gain sub-seafloor perspective on these features the MCS data are draped below the bathymetry/backscatter grids using QPS Fledermaus. From this perspective, specific locations for detailed velocity and attribute analysis of the sediment section are chosen. Sediment velocity and attribute analysis also provide insight into apparent differences in the sediment section and décollement formation along the Oregon and Washington plate transects. While both lines intersect areas of dense pockmark concentration, the area around the Oregon transect has been shown to contain a continuous

  12. Multi-channel Data Acquisition System for a 500 m DC HTS Power Cable in Ishikari

    NASA Astrophysics Data System (ADS)

    Ivanov, Yury V.; Chikumoto, Noriko; Watanabe, Hirofumi; Takano, Hirohisa; Inoue, Noriyuki; Yamaguchi, Satarou

    Reduction of heat penetrating into the cryogenic region is the important method of optimization of superconducting devices. In the cases of short-range power transmission lines and compact HTS devices like magnets, the heat leakage through current leads is relatively large. In order to decrease this contribution, current leads equipped with Peltier elements can be used. The mentioned technology is being actively developed in the Chubu University. Commercial samples of Peltier current leads are installed at the terminals of 500-meter DC HTS cable in Ishikari (Hokkaido). This cable is designed for 5 kA. The inner conducting layer consists of 37 DI-BSCCO HTS tapes from Sumitomo Electric Industries, Ltd. with a critical current of 180 A; and the outer one consists of 35 tapes of the same type. Each end of the cable's tape is connected to the individual Peltier current lead. Accordingly, each of the two terminals is equipped with 72 Peltier current leads, 144 pieces in total. In order to examine behavior of the current leads in detail, each piece is supplied with two thermocouples; there are also voltage taps on feedthrough and on HTS tape end. In addition, current through Peltier current lead can be measured by means of individual current transformer. The hardware part of the data acquisition system includes four Keithley 3706A multimeters equipped with 60-channel model 3724 FET multiplexer cards. Therefore, 144 data blocks are formed. Furthermore, there are 72 measurements of a voltage drop across HTS tape. Sampling period is set to be 3 s. The program part of the data acquisition system was written using LabVIEW software solution (National Instruments Corp.).

  13. Development of the analog ASIC for multi-channel readout X-ray CCD camera

    NASA Astrophysics Data System (ADS)

    Nakajima, Hiroshi; Matsuura, Daisuke; Idehara, Toshihiro; Anabuki, Naohisa; Tsunemi, Hiroshi; Doty, John P.; Ikeda, Hirokazu; Katayama, Haruyoshi; Kitamura, Hisashi; Uchihori, Yukio

    2011-03-01

    We report on the performance of an analog application-specific integrated circuit (ASIC) developed aiming for the front-end electronics of the X-ray CCD camera system onboard the next X-ray astronomical satellite, ASTRO-H. It has four identical channels that simultaneously process the CCD signals. Distinctive capability of analog-to-digital conversion enables us to construct a CCD camera body that outputs only digital signals. As the result of the front-end electronics test, it works properly with low input noise of ≤30μV at the pixel rate below 100 kHz. The power consumption is sufficiently low of ˜150mW/chip. The input signal range of ±20 mV covers the effective energy range of the typical X-ray photon counting CCD (up to 20 keV). The integrated non-linearity is 0.2% that is similar as those of the conventional CCDs in orbit. We also performed a radiation tolerance test against the total ionizing dose (TID) effect and the single event effect. The irradiation test using 60Co and proton beam showed that the ASIC has the sufficient tolerance against TID up to 200 krad, which absolutely exceeds the expected amount of dose during the period of operating in a low-inclination low-earth orbit. The irradiation of Fe ions with the fluence of 5.2×108 Ion/cm2 resulted in no single event latchup (SEL), although there were some possible single event upsets. The threshold against SEL is higher than 1.68 MeV cm2/mg, which is sufficiently high enough that the SEL event should not be one of major causes of instrument downtime in orbit.

  14. Recent Progress of the HL-2A Multi-Channel HCOOH Laser Interferometer/Polarimeter

    NASA Astrophysics Data System (ADS)

    Li, Yonggao; Zhou, Yan; Deng, Zhongchao; Li, Yuan; Yi, Jiang; Wang, Haoxi

    2015-05-01

    A multichannel methanoic acid (HCOOH, λ = 432.5 μm) laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide (HCN, λ = 337 μm) laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of ˜30 mW, and a power stability <10% in 50 min. A beam waist (diameter d0 ≈12.0 mm, about 200 mm away from the outlet) is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase-comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign. supported by the National Magnetic Confinement Fusion Science Programs of China (Nos. 2010GB101002 and 2014GB109001), and National Natural Science Foundation of China (Nos. 11075048 and 11275059)

  15. Optimization of a digital lock-in algorithm with a square-wave reference for frequency-divided multi-channel sensor signal detection

    NASA Astrophysics Data System (ADS)

    Zhang, Shengzhao; Li, Gang; Lin, Ling; Zhao, Jing

    2016-08-01

    A digital lock-in detection technique is commonly used to measure the amplitude and phase of a selected frequency signal. A technique that uses a square wave as the reference signal has an advantage over the one using a sinusoidal wave due to its easier implementation and higher computational efficiency. However, demodulating multiple-frequency composite signals using square wave reference may result in interference between channels. To avoid interference between channels and reduce the computational complexity, we modify the calculations and determine the optimal parameter settings of the low-pass filter and carrier frequency, as detailed in this paper. The results of our analysis show that when the length of the average filter and carrier frequencies are properly set, the interference between the channels is removed. This optimization produces the digital lock-in detection suitable for measuring multi-channel sensor signals.

  16. Optimization of a digital lock-in algorithm with a square-wave reference for frequency-divided multi-channel sensor signal detection.

    PubMed

    Zhang, Shengzhao; Li, Gang; Lin, Ling; Zhao, Jing

    2016-08-01

    A digital lock-in detection technique is commonly used to measure the amplitude and phase of a selected frequency signal. A technique that uses a square wave as the reference signal has an advantage over the one using a sinusoidal wave due to its easier implementation and higher computational efficiency. However, demodulating multiple-frequency composite signals using square wave reference may result in interference between channels. To avoid interference between channels and reduce the computational complexity, we modify the calculations and determine the optimal parameter settings of the low-pass filter and carrier frequency, as detailed in this paper. The results of our analysis show that when the length of the average filter and carrier frequencies are properly set, the interference between the channels is removed. This optimization produces the digital lock-in detection suitable for measuring multi-channel sensor signals. PMID:27587155

  17. Highly Sensitive Multi-Channel IDC Sensor Array for Low Concentration Taste Detection

    PubMed Central

    Khan, Md. Rajibur Rahaman; Kang, Shin-Won

    2015-01-01

    In this study, we designed and developed an interdigitated capacitor (IDC)-based taste sensor array to detect different taste substances. The designed taste sensing array has four IDC sensing elements. The four IDC taste sensing elements of the array are fabricated by incorporating four different types of lipids into the polymer, dioctyl phenylphosphonate (DOPP) and tetrahydrofuran (THF) to make the respective dielectric materials that are individually placed onto an interdigitated electrode (IDE) via spin coating. When the dielectric material of an IDC sensing element comes into contact with a taste substance, its dielectric properties change with the capacitance of the IDC sensing element; this, in turn, changes the voltage across the IDC, as well as the output voltage of each channel of the system. In order to assess the effectiveness of the sensing system, four taste substances, namely sourness (HCl), saltiness (NaCl), sweetness (glucose) and bitterness (quinine-HCl), were tested. The IDC taste sensor array had rapid response and recovery times of about 12.9 s and 13.39 s, respectively, with highly stable response properties. The response property of the proposed IDC taste sensor array was linear, and its correlation coefficient R2 was about 0.9958 over the dynamic range of the taste sensor array as the taste substance concentration was varied from 1 μM to 1 M. The proposed IDC taste sensor array has several other advantages, such as real-time monitoring capabilities, high sensitivity 45.78 mV/decade, good reproducibility with a standard deviation of about 0.029 and compactness, and the circuitry is based on readily available and inexpensive electronic components. The proposed IDC taste sensor array was compared with the potentiometric taste sensor with respect to sensitivity, dynamic range width, linearity and response time. We found that the proposed IDC sensor array has better performance. Finally, principal component analysis (PCA) was applied to

  18. Multi-channel terahertz wavelength division demultiplexer with defects-coupled photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Li, Shaopeng; Liu, Hongjun; Sun, Qibing; Huang, Nan

    2016-05-01

    Terahertz (THz) wavelength division demultiplexer based on a compact defects-coupled photonic crystal waveguide is proposed and demonstrated numerically. This device consists of an input waveguide that perpendicularly coupled with a series of defects cavities, each of which captures the resonance frequency from the input waveguide. Coupled-mode theory and finite element method are used to analyze the transmission properties of the structure. It is found that the transmission wavelength centered around 1 THz can be adjusted by changing the geometrical parameters of defects cavities, which equals to THz waves generated by optical methods such as difference frequency generation and optical rectification. Applications in this frequency range are urgently needed. Furthermore, the highest transmission efficiency of 0.94 can be achieved when a perfect wavelength-selective mirror is set in the output waveguide.

  19. Online multi-channel microfluidic chip-mass spectrometry and its application for quantifying noncovalent protein-protein interactions.

    PubMed

    Liu, Wu; Chen, Qiushui; Lin, Xuexia; Lin, Jin-Ming

    2015-03-01

    To establish an automatic and online microfluidic chip-mass spectrometry (chip-MS) system, a device was designed and fabricated for microsampling by a hybrid capillary. The movement of the capillary was programmed by a computer to aspirate samples from different microfluidic channels in the form of microdroplets (typically tens of nanoliters in volume), which were separated by air plugs. The droplets were then directly analyzed by MS via paper spray ionization without any pretreatment. The feasibility and performance were demonstrated by a concentration gradient experiment. Furthermore, after eliminating the effect of nonuniform response factors by an internal standard method, determination of the association constant within a noncovalent protein-protein complex was successfully accomplished with the MS-based titration indicating the versatility and the potential of this novel platform for widespread applications. PMID:25597452

  20. Studies of the degradation mechanisms in high-power diode lasers using multi-channel micro-thermography

    NASA Astrophysics Data System (ADS)

    Kozłowska, Anna; Tomm, Jens W.; Wawrzyniak, Piotr; Maląg, Andrzej; Weik, Fritz; Latoszek, Mateusz

    2005-09-01

    We demonstrate the applicability of imaging thermography for investigations of mechanisms associated with gradual degradation in diode lasers. The introduction of two spectral channels provides the means for separate observation of deep level luminescence and thermal radiation emitted according to Planck's law. In the near IR region we found the signal detected by the camera to be mainly affected by mid-gap deep-level luminescence. An intensity increase of the luminescence signal for an aged diode laser compared to an unaged device is noticed. It can be explained by an increase of deep level defect concentration during the aging. In the mid IR, we mainly encounter thermal radiation, which can be used for the analysis of the thermal properties of devices. In present work the thermal behavior of the device subjected to an aging of 3000 hours is analyzed. A significant increase of device temperature is noticed.

  1. Passive multi-channel analysis of surface waves with cross-correlations and beamforming. Application to a sea dike

    NASA Astrophysics Data System (ADS)

    Le Feuvre, M.; Joubert, A.; Leparoux, D.; Côte, P.

    2015-03-01

    We introduce the use of cross-correlations in the passive multi-channel analysis of surface waves (MASW), and report an improvement in the determination of subsurface shear velocities from ambient seismic noise. Velocities are measured from phase-shifts that are also related to the source location. Consequently, the accuracy with which velocities can be inferred depends on the ability of the array to locate noise sources. The computation of cross-correlations for each receiver pair allows increasing the effective spatial sampling of the array. For this reason, we show that beamforming is more efficient with cross-correlated signals. Consequently, MASW performed with cross-correlations produces a dispersion diagram where aliasing is reduced and signal-to-noise ratio increased. The proposed method is validated with synthetic records. It is then applied on passive recordings obtained on top of a sea dike at high tide, where sea waves were acting as continuous seismic sources. Surface wave velocities that favorably compare with hammer shot measurements are inferred.

  2. Evaluation of the potential of soil remediation by direct multi-channel pulsed corona discharge in soil.

    PubMed

    Wang, Tie Cheng; Qu, Guangzhou; Li, Jie; Liang, Dongli

    2014-01-15

    A novel approach, named multi-channel pulsed corona discharge in soil, was developed for remediating organic pollutants contaminated soil, with p-nitrophenol (PNP) as the model pollutant. The feasibility of PNP degradation in soil was explored by evaluating effects of pulse discharge voltage, air flow rate and soil moisture on PNP degradation. Based on roles of chemically active species and evolution of degradation intermediates, PNP degradation processes were discussed. Experimental results showed that about 89.4% of PNP was smoothly degraded within 60min of discharge treatment at pulse discharge voltage 27kV, soil moisture 5% and air flow rate 0.8Lmin(-1), and the degradation process fitted the first-order kinetic model. Increasing pulse discharge voltage was found to be favorable for PNP degradation, but not for energy yield. There existed appropriate air flow rate and soil moisture for obtaining gratifying PNP degradation efficacy. Roles of radical scavenger and measurement of active species suggested that ozone, H2O2, and OH radicals played very important roles in PNP degradation. CN bond in PNP molecule was cleaved, and the main intermediate products such as hydroquinone, benzoquinone, catechol, phenol, acetic acid, formic acid, oxalic acid, NO2(-) and NO3(-) were identified. Possible pathway of PNP degradation in soil in such a system was proposed. PMID:24295768

  3. Design and performance of a fiber array coupled multi-channel photon counting, 3D imaging, airborne lidar system

    NASA Astrophysics Data System (ADS)

    Huang, Genghua; Shu, Rong; Hou, Libing; Li, Ming

    2014-06-01

    Photon counting lidar has an ultra-high sensitivity which can be hundreds even thousands of times higher than the linear detection lidar. It can significantly increase the system's capability of detection rang and imaging density, saving size and power consumings in airborne or space-borne applications. Based on Geiger-mode Si avalanche photodiodes (Si-APD), a prototype photon counting lidar which used 8 APDs coupled with a 1×8-pixel fiber array has been made in June, 2011. The experiments with static objects showed that the photon counting lidar could operate in strong solar background with 0.04 receiving photoelectrons on average. Limited by less counting times in moving platforms, the probability of detection and the 3D imaging density would be lower than that in static platforms. In this paper, a latest fiber array coupled multi-channel photon counting, 3D imaging, airborne lidar system is introduced. The correlation range receiver algorithm of photon counting 3D imaging is improved for airborne signal photon events extraction and noise filter. The 3D imaging experiments in the helicopter shows that the false alarm rate is less than 6×10-7, and the correct rate is better than 99.9% with 4 received photoelectrons and 0.7MHz system noise on average.

  4. A multi-channel opto-electronic sensor to accurately monitor heart rate against motion artefact during exercise.

    PubMed

    Alzahrani, Abdullah; Hu, Sijung; Azorin-Peris, Vicente; Barrett, Laura; Esliger, Dale; Hayes, Matthew; Akbare, Shafique; Achart, Jérôme; Kuoch, Sylvain

    2015-01-01

    This study presents the use of a multi-channel opto-electronic sensor (OEPS) to effectively monitor critical physiological parameters whilst preventing motion artefact as increasingly demanded by personal healthcare. The aim of this work was to study how to capture the heart rate (HR) efficiently through a well-constructed OEPS and a 3-axis accelerometer with wireless communication. A protocol was designed to incorporate sitting, standing, walking, running and cycling. The datasets collected from these activities were processed to elaborate sport physiological effects. t-test, Bland-Altman Agreement (BAA), and correlation to evaluate the performance of the OEPS were used against Polar and Mio-Alpha HR monitors. No differences in the HR were found between OEPS, and either Polar or Mio-Alpha (both p > 0.05); a strong correlation was found between Polar and OEPS (r: 0.96, p < 0.001); the bias of BAA 0.85 bpm, the standard deviation (SD) 9.20 bpm, and the limits of agreement (LOA) from -17.18 bpm to +18.88 bpm. For the Mio-Alpha and OEPS, a strong correlation was found (r: 0.96, p < 0.001); the bias of BAA 1.63 bpm, SD 8.62 bpm, LOA from -15.27 bpm to +18.58 bpm. These results demonstrate the OEPS to be capable of carrying out real time and remote monitoring of heart rate. PMID:26473860

  5. Computerized image analysis of cell-cell interactions in human renal tissue by using multi-channel immunoflourescent confocal microscopy

    NASA Astrophysics Data System (ADS)

    Peng, Yahui; Jiang, Yulei; Liarski, Vladimir M.; Kaverina, Natalya; Clark, Marcus R.; Giger, Maryellen L.

    2012-03-01

    Analysis of interactions between B and T cells in tubulointerstitial inflammation is important for understanding human lupus nephritis. We developed a computer technique to perform this analysis, and compared it with manual analysis. Multi-channel immunoflourescent-microscopy images were acquired from 207 regions of interest in 40 renal tissue sections of 19 patients diagnosed with lupus nephritis. Fresh-frozen renal tissue sections were stained with combinations of immunoflourescent antibodies to membrane proteins and counter-stained with a cell nuclear marker. Manual delineation of the antibodies was considered as the reference standard. We first segmented cell nuclei and cell membrane markers, and then determined corresponding cell types based on the distances between cell nuclei and specific cell-membrane marker combinations. Subsequently, the distribution of the shortest distance from T cell nuclei to B cell nuclei was obtained and used as a surrogate indicator of cell-cell interactions. The computer and manual analyses results were concordant. The average absolute difference was 1.1+/-1.2% between the computer and manual analysis results in the number of cell-cell distances of 3 μm or less as a percentage of the total number of cell-cell distances. Our computerized analysis of cell-cell distances could be used as a surrogate for quantifying cell-cell interactions as either an automated and quantitative analysis or for independent confirmation of manual analysis.

  6. A Multi-channel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3D Vestibular Sensation

    PubMed Central

    Della Santina, Charles C.; Migliaccio, Americo A.; Patel, Amit H.

    2009-01-01

    Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode’s targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior. PMID:17554821

  7. A Multi-Channel Opto-Electronic Sensor to Accurately Monitor Heart Rate against Motion Artefact during Exercise

    PubMed Central

    Alzahrani, Abdullah; Hu, Sijung; Azorin-Peris, Vicente; Barrett, Laura; Esliger, Dale; Hayes, Matthew; Akbare, Shafique; Achart, Jérôme; Kuoch, Sylvain

    2015-01-01

    This study presents the use of a multi-channel opto-electronic sensor (OEPS) to effectively monitor critical physiological parameters whilst preventing motion artefact as increasingly demanded by personal healthcare. The aim of this work was to study how to capture the heart rate (HR) efficiently through a well-constructed OEPS and a 3-axis accelerometer with wireless communication. A protocol was designed to incorporate sitting, standing, walking, running and cycling. The datasets collected from these activities were processed to elaborate sport physiological effects. t-test, Bland-Altman Agreement (BAA), and correlation to evaluate the performance of the OEPS were used against Polar and Mio-Alpha HR monitors. No differences in the HR were found between OEPS, and either Polar or Mio-Alpha (both p > 0.05); a strong correlation was found between Polar and OEPS (r: 0.96, p < 0.001); the bias of BAA 0.85 bpm, the standard deviation (SD) 9.20 bpm, and the limits of agreement (LOA) from −17.18 bpm to +18.88 bpm. For the Mio-Alpha and OEPS, a strong correlation was found (r: 0.96, p < 0.001); the bias of BAA 1.63 bpm, SD 8.62 bpm, LOA from −15.27 bpm to +18.58 bpm. These results demonstrate the OEPS to be capable of carrying out real time and remote monitoring of heart rate. PMID:26473860

  8. Functional connectivity during phonemic and semantic verbal fluency test: a multi-channel near infrared spectroscopy study (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Huang, Chun-Jung; Sun, Chia-Wei; Chou, Po-Han; Chuang, Ching-Cheng

    2016-03-01

    Verbal fluency tests (VFT) are widely used neuropsychological tests of frontal lobe and have been frequently used in various functional brain mapping studies. There are two versions of VFT based on the type of cue: the letter fluency task (LFT) and the category fluency task (CFT). However, the fundamental aspect of the brain connectivity across spatial regions of the fronto-temporal regions during the VFTs has not been elucidated to date. In this study we hypothesized that different cortical functional connectivity over bilateral fronto-temporal regions can be observed by means of multi-channel fNIRS in the LFT and the CFT respectively. Our results from fNIRS (ETG-4000) showed different patterns of brain functional connectivity consistent with these different cognitive requirements. We demonstrate more brain functional connectivity over frontal and temporal regions during LFT than CFT, and this was in line with previous brain activity studies using fNIRS demonstrating increased frontal and temporal region activation during LFT and CFT and more pronounced frontal activation by the LFT.

  9. Pitch control of multi-channel graded-index core polymer waveguide for optical PCB using the Mosquito method

    NASA Astrophysics Data System (ADS)

    Kinoshita, Ryota; Suganuma, Daisuke; Ishigure, Takaaki

    2014-03-01

    We successfully fabricate multi-channel GI circular-core polymer waveguides with precisely controlled pitches utilizing the Mosquito method. The Mosquito method is a very simple method for fabricating GI-core polymer optical waveguides that utilizes a micro dispenser. In this method, a viscous core monomer is directly dispensed into a cladding monomer layer before UV cured, and circular cores are formed by curing both the core and cladding under a UV exposure. Here, it is a concern that a needle position accuracy influences on the interchannel pitch when parallel cores are fabricated by parallel repetitive scan of a single needle. However, we succeeded in controlling the pitch with the Mosquito method and then, GI-core waveguides with 250.7+/-5.2 μm, 126.7+/-2.6 μm and 61.7+/-3.4 μm are successfully fabricated for the pre-set values of 250 μm, 125 μm and 62.5 μm, respectively. Then, we demonstrate a 4 × 10 Gbps transmission over the fabricated GI-core waveguide by connecting the waveguide to an MMF ribbon with a 250-μm pitch, which is realized because the pitch of the fabricated waveguide is accurately controlled to 250 μm.

  10. Do you see what I hear: experiments in multi-channel sound and 3D visualization for network monitoring?

    NASA Astrophysics Data System (ADS)

    Ballora, Mark; Hall, David L.

    2010-04-01

    Detection of intrusions is a continuing problem in network security. Due to the large volumes of data recorded in Web server logs, analysis is typically forensic, taking place only after a problem has occurred. This paper describes a novel method of representing Web log information through multi-channel sound, while simultaneously visualizing network activity using a 3-D immersive environment. We are exploring the detection of intrusion signatures and patterns, utilizing human aural and visual pattern recognition ability to detect intrusions as they occur. IP addresses and return codes are mapped to an informative and unobtrusive listening environment to act as a situational sound track of Web traffic. Web log data is parsed and formatted using Python, then read as a data array by the synthesis language SuperCollider [1], which renders it as a sonification. This can be done either for the study of pre-existing data sets or in monitoring Web traffic in real time. Components rendered aurally include IP address, geographical information, and server Return Codes. Users can interact with the data, speeding or slowing the speed of representation (for pre-existing data sets) or "mixing" sound components to optimize intelligibility for tracking suspicious activity.

  11. A 12-bit 1 MS/s SAR-ADC for multi-channel CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Wei, Liu; Tingcun, Wei; Bo, Li; Panjie, Guo; Yongcai, Hu

    2015-04-01

    This paper presents a low power, area-efficient and radiation-hardened 12-bit 1 MS/s successive approximation register (SAR) analog-to-digital converter (ADC) for multi-channel CdZnTe (CZT) detector applications. In order to improve the SAR-ADC's accuracy, a novel comparator is proposed in which the offset voltage is self-calibrated and also a new architecture for the unit capacitor array is proposed to reduce the capacitance mismatches in the charge-redistribution DAC. The ability to radiation-harden the SAR-ADC is enhanced through circuit and layout design technologies. The prototype chip was fabricated using a TSMC 0.35 μm 2P4M CMOS process. At a 3.3/5 V power supply and a sampling rate of 1 MS/s, the proposed SAR-ADC achieves a peak signal to noise and distortion ratio (SINAD) of 67.64 dB and consumes only 10 mW power. The core of the prototype chip occupies an active area of 1180 × 1080 μm2. Project supported by the Special-Funded Program on National Key Scientific Instruments and Equipment Development (No. 2011YQ040082).

  12. Prefrontal Hemodynamic Functions during a Verbal Fluency Task in Blepharospasm Using Multi-Channel NIRS.

    PubMed

    Shen, Chen-Yu; Wang, Yong-Jun; Zhang, Xiao-Qian; Liu, Xiao-Min; Ren, Xia-Jin; Ma, Xiang-Yun; Sun, Jing-Jing; Feng, Kun; Sun, Gao-Xiang; Xu, Bo; Liu, Po-Zi

    2016-01-01

    Blepharospasm (BSP) has a morbidity of 16 to 133 per million and is characterized by orbicularis oculi spasms. BSP can severely impact daily life. However, to date, its pathophysiology has not been clearly demonstrated. Near-infrared spectroscopy (NIRS) is a portable, non-invasive, and high time resolution apparatus used to measure cerebral blood flow. This study aimed to investigate the hemodynamic response patterns of BSP patients and determine whether BSP alone can be an attributional factor to influence the function of the prefrontal area using a verbal fluency task (VFT) and NIRS. Twenty-three BSP patients (10 males and 13 females) and 13 healthy controls (HC; five males and eight females) matched by gender and education were examined using NIRS. BSP patients were divided into two groups based on the presence or absence of depression and anxiety symptoms. A covariance analysis was conducted to analyze differences between the three groups and reduce the influence of different ages and educational levels. Bonferroni was used to process the post hoc test. The bilateral orbitofrontal area (ch36, 39, and 41; P<0.01) exhibited a lower activation in BSP patients without psychiatric symptoms compared with HC. This study is the first report to identify the prefrontal function in BSP using NIRS. Our findings indicate that BSP alone may cause a hypoactive hemodynamic performance in the prefrontal cortex in the absence of psychiatric symptoms. These findings provide evidence to support novel pathophysiological mechanisms of BSP. PMID:26942579

  13. Prefrontal Hemodynamic Functions during a Verbal Fluency Task in Blepharospasm Using Multi-Channel NIRS

    PubMed Central

    Zhang, Xiao-Qian; Liu, Xiao-Min; Ren, Xia-Jin; Ma, Xiang-Yun; Sun, Jing-Jing; Feng, Kun; Sun, Gao-Xiang; Xu, Bo; Liu, Po-Zi

    2016-01-01

    Blepharospasm (BSP) has a morbidity of 16 to 133 per million and is characterized by orbicularis oculi spasms. BSP can severely impact daily life. However, to date, its pathophysiology has not been clearly demonstrated. Near-infrared spectroscopy (NIRS) is a portable, non-invasive, and high time resolution apparatus used to measure cerebral blood flow. This study aimed to investigate the hemodynamic response patterns of BSP patients and determine whether BSP alone can be an attributional factor to influence the function of the prefrontal area using a verbal fluency task (VFT) and NIRS. Twenty-three BSP patients (10 males and 13 females) and 13 healthy controls (HC; five males and eight females) matched by gender and education were examined using NIRS. BSP patients were divided into two groups based on the presence or absence of depression and anxiety symptoms. A covariance analysis was conducted to analyze differences between the three groups and reduce the influence of different ages and educational levels. Bonferroni was used to process the post hoc test. The bilateral orbitofrontal area (ch36, 39, and 41; P<0.01) exhibited a lower activation in BSP patients without psychiatric symptoms compared with HC. This study is the first report to identify the prefrontal function in BSP using NIRS. Our findings indicate that BSP alone may cause a hypoactive hemodynamic performance in the prefrontal cortex in the absence of psychiatric symptoms. These findings provide evidence to support novel pathophysiological mechanisms of BSP. PMID:26942579

  14. Quantitative complexity analysis in multi-channel intracranial EEG recordings form epilepsy brains

    PubMed Central

    Liu, Chang-Chia; Pardalos, Panos M.; Chaovalitwongse, W. Art; Shiau, Deng-Shan; Ghacibeh, Georges; Suharitdamrong, Wichai; Sackellares, J. Chris

    2008-01-01

    Epilepsy is a brain disorder characterized clinically by temporary but recurrent disturbances of brain function that may or may not be associated with destruction or loss of consciousness and abnormal behavior. Human brain is composed of more than 10 to the power 10 neurons, each of which receives electrical impulses known as action potentials from others neurons via synapses and sends electrical impulses via a sing output line to a similar (the axon) number of neurons. When neuronal networks are active, they produced a change in voltage potential, which can be captured by an electroencephalogram (EEG). The EEG recordings represent the time series that match up to neurological activity as a function of time. By analyzing the EEG recordings, we sought to evaluate the degree of underlining dynamical complexity prior to progression of seizure onset. Through the utilization of the dynamical measurements, it is possible to classify the state of the brain according to the underlying dynamical properties of EEG recordings. The results from two patients with temporal lobe epilepsy (TLE), the degree of complexity start converging to lower value prior to the epileptic seizures was observed from epileptic regions as well as non-epileptic regions. The dynamical measurements appear to reflect the changes of EEG’s dynamical structure. We suggest that the nonlinear dynamical analysis can provide a useful information for detecting relative changes in brain dynamics, which cannot be detected by conventional linear analysis. PMID:19079790

  15. Generation of multi-wavelength picosecond pulses with tunable pulsewidth and channel spacing using a Raman amplification-based adiabatic soliton compressor.

    PubMed

    Nguyen-The, Quang; Tan, Hung Nguyen; Matsuura, Motoharu; Kishi, Naoto

    2012-01-16

    We experimentally demonstrate pulsewidth-tunable picosecond multi-wavelength pulse generation at 10 Gb/s by the use of a Raman amplification-based adiabatic soliton compressor (RA-ASC). Multi-wavelength seed pulse trains are generated by a commercially available electroabsorption modulator and then compressed by using the RA-ASC. The pulsewidths of the compressed pulses can be simultaneously controlled from 16.0 ps to 2.0 ps by adjusting Raman pump power. Operating wavelength range of our scheme are also investigated, showing the possibility for wide channel spacing operations. PMID:22274467

  16. Multi-channel seismic reflection database for the northern Gulf of California, a highly-sedimented oblique rift

    NASA Astrophysics Data System (ADS)

    Steckler, M. S.; Haxby, W.; Persaud, P.; Stock, J.; Martín-Barajas, A.; Diebold, J.; Gonzalez-Fernandez, A.; Mountain, G. S.

    2003-04-01

    A multi-channel seismic reflection database has been developed to give access to high-resolution MCS data collected in the northern Gulf of California in May-June 1999. This data set consists of 3500 km of high-resolution MCS data acquired by the LDEO portable 48-channel MCS system using a 600-m streamer, a 1-ms sampling interval, and CDP spacing of 6.25/12.5 m on board the B/O Ulloa, the 28-m research vessel of CICESE. The resulting images have vertical resolution on the scale of meters to depths of up to 2 km below the seafloor. In addition, 48 sonobuoys recorded to 7 sec TWTT provided refraction velocities to greater depths. The northern Gulf of California is a transitional region between the oceanic ridge transform system of the central and southern Gulf and the continental San Andreas fault system of southern California. This data images the active deformation associated with the plate boundary zone in the northern Gulf of California. Multiple parallel rifts are simultaneously active in this wide complex zone of regional extension overprinted by shearing and a high sediment influx. The public-access database makes the cruise results, which is in a US MARGINS Program focus area, available to the broader geoscience community. The database includes navigation, final stacks and images for 80 seismic lines and 48 sonobuoys. The database may be accessed with MapApp, a downloadable Java application. Java applets offer many advantages over static or scripted web pages; they permit dynamic local interaction with data sets and limit time-consuming interaction with a remote server. MapApp displays the seismic lines on a map, and provides a viewer for inspecting images of the lines. Users may select a line from a list, or by clicking on the map. Once a line is selected, a user may load the image into the viewer, or download navigation, image or SEG-Y files. The viewer includes capability to zoom in and out, scroll, stretch or shrink horizontally, reverse direction, and

  17. From Complex B1 Mapping to Local SAR Estimation for Human Brain MR Imaging Using Multi-channel Transceiver Coil at 7T

    PubMed Central

    Zhang, Xiaotong; Schmitter, Sebastian; Van de Moortel, Pierre-François; Liu, Jiaen

    2014-01-01

    Elevated Specific Absorption Rate (SAR) associated with increased main magnetic field strength remains as a major safety concern in ultra-high-field (UHF) Magnetic Resonance Imaging (MRI) applications. The calculation of local SAR requires the knowledge of the electric field induced by radiofrequency (RF) excitation, and the local electrical properties of tissues. Since electric field distribution cannot be directly mapped in conventional MR measurements, SAR estimation is usually performed using numerical model-based electromagnetic simulations which, however, are highly time consuming and cannot account for the specific anatomy and tissue properties of the subject undergoing a scan. In the present study, starting from the measurable RF magnetic fields (B1) in MRI, we conducted a series of mathematical deduction to estimate the local, voxel-wise and subject-specific SAR for each single coil element using a multi-channel transceiver array coil. We first evaluated the feasibility of this approach in numerical simulations including two different human head models. We further conducted experimental study in a physical phantom and in two human subjects at 7T using a multi-channel transceiver head coil. Accuracy of the results is discussed in the context of predicting local SAR in the human brain at UHF MRI using multi-channel RF transmission. PMID:23508259

  18. Cutaneous sensory nerve as a substitute for auditory nerve in solving deaf-mutes’ hearing problem: an innovation in multi-channel-array skin-hearing technology

    PubMed Central

    Li, Jianwen; Li, Yan; Zhang, Ming; Ma, Weifang; Ma, Xuezong

    2014-01-01

    The current use of hearing aids and artificial cochleas for deaf-mute individuals depends on their auditory nerve. Skin-hearing technology, a patented system developed by our group, uses a cutaneous sensory nerve to substitute for the auditory nerve to help deaf-mutes to hear sound. This paper introduces a new solution, multi-channel-array skin-hearing technology, to solve the problem of speech discrimination. Based on the filtering principle of hair cells, external voice signals at different frequencies are converted to current signals at corresponding frequencies using electronic multi-channel bandpass filtering technology. Different positions on the skin can be stimulated by the electrode array, allowing the perception and discrimination of external speech signals to be determined by the skin response to the current signals. Through voice frequency analysis, the frequency range of the band-pass filter can also be determined. These findings demonstrate that the sensory nerves in the skin can help to transfer the voice signal and to distinguish the speech signal, suggesting that the skin sensory nerves are good candidates for the replacement of the auditory nerve in addressing deaf-mutes’ hearing problems. Scientific hearing experiments can be more safely performed on the skin. Compared with the artificial cochlea, multi-channel-array skin-hearing aids have lower operation risk in use, are cheaper and are more easily popularized. PMID:25317171

  19. Investigation of verbal and visual working memory by multi-channel time-resolved functional near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Contini, D.; Caffini, M.; Re, R.; Zucchelli, L.; Spinelli, L.; Basso Moro, S.; Bisconti, S.; Ferrari, M.; Quaresima, V.; Cutini, S.; Torricelli, A.

    2013-03-01

    Working memory (WM) is fundamental for a number of cognitive processes, such as comprehension, reasoning and learning. WM allows the short-term maintenance and manipulation of the information selected by attentional processes. The goal of this study was to examine by time-resolved fNIRS neural correlates of the verbal and visual WM during forward and backward digit span (DF and DB, respectively) tasks, and symbol span (SS) task. A neural dissociation was hypothesised between the maintenance and manipulation processes. In particular, a dorsolateral/ventrolateral prefrontal cortex (DLPFC/VLPFC) recruitment was expected during the DB task, whilst a lateralised involvement of Brodmann Area (BA) 10 was expected during the execution of the DF task. Thirteen subjects were monitored by a multi-channel, dual-wavelength (690 and 829 nm) time-resolved fNIRS system during 3 minutes long DF and DB tasks and 4 minutes long SS task. The participants' mean memory span was calculated for each task: DF: 6.46+/-1.05 digits; DB: 5.62+/-1.26 digits; SS: 4.69+/-1.32 symbols. No correlation was found between the span level and the heart rate data (measured by pulse oximeter). As expected, DB elicited a broad activated area, in the bilateral VLPFC and the right DLPFC, whereas a more localised activation was observed over the right hemisphere during either DF (BA 10) or SS (BA 10 and 44). The robust involvement of the DLPFC during DB, compared to DF, is compatible with previous findings and with the key role of the central executive subserving in manipulating processes.

  20. A novel LabVIEW-based multi-channel non-invasive abdominal maternal-fetal electrocardiogram signal generator.

    PubMed

    Martinek, Radek; Kelnar, Michal; Koudelka, Petr; Vanus, Jan; Bilik, Petr; Janku, Petr; Nazeran, Homer; Zidek, Jan

    2016-02-01

    This paper describes the design, construction, and testing of a multi-channel fetal electrocardiogram (fECG) signal generator based on LabVIEW. Special attention is paid to the fetal heart development in relation to the fetus' anatomy, physiology, and pathology. The non-invasive signal generator enables many parameters to be set, including fetal heart rate (FHR), maternal heart rate (MHR), gestational age (GA), fECG interferences (biological and technical artifacts), as well as other fECG signal characteristics. Furthermore, based on the change in the FHR and in the T wave-to-QRS complex ratio (T/QRS), the generator enables manifestations of hypoxic states (hypoxemia, hypoxia, and asphyxia) to be monitored while complying with clinical recommendations for classifications in cardiotocography (CTG) and fECG ST segment analysis (STAN). The generator can also produce synthetic signals with defined properties for 6 input leads (4 abdominal and 2 thoracic). Such signals are well suited to the testing of new and existing methods of fECG processing and are effective in suppressing maternal ECG while non-invasively monitoring abdominal fECG. They may also contribute to the development of a new diagnostic method, which may be referred to as non-invasive trans-abdominal CTG +  STAN. The functional prototype is based on virtual instrumentation using the LabVIEW developmental environment and its associated data acquisition measurement cards (DAQmx). The generator also makes it possible to create synthetic signals and measure actual fetal and maternal ECGs by means of bioelectrodes. PMID:26799770

  1. Calibration of the R/V Marcus G. Langseth Seismic Array in shallow Cascadia waters using the Multi-Channel Streamer

    NASA Astrophysics Data System (ADS)

    Crone, T. J.; Tolstoy, M.; Carton, H. D.

    2013-12-01

    In the summer of 2012, two multi-channel seismic (MCS) experiments, Cascadia Open-Access Seismic Transects (COAST) and Ridge2Trench, were conducted in the offshore Cascadia region. An area of growing environmental concern with active source seismic experiments is the potential impact of the received sound on marine mammals, but data relating to this issue is limited. For these surveys sound level 'mitigation radii' are established for the protection of marine mammals, based on direct arrival modeling and previous calibration experiments. Propagation of sound from seismic arrays can be accurately modeled in deep-water environments, but in shallow and sloped environments the complexity of local geology and bathymetry can make it difficult to predict sound levels as a function of distance from the source array. One potential solution to this problem is to measure the received levels in real-time using the ship's streamer (Diebold et al., 2010), which would allow the dynamic determination of suitable mitigation radii. We analyzed R/V Langseth streamer data collected on the shelf and slope off the Washington coast during the COAST experiment to measure received levels in situ up to 8 km away from the ship. Our analysis shows that water depth and bathymetric features can affect received levels in shallow water environments. The establishment of dynamic mitigation radii based on local conditions may help maximize the safety of marine mammals while also maximizing the ability of scientists to conduct seismic research. With increasing scientific and societal focus on subduction zone environments, a better understanding of shallow water sound propagation is essential for allowing seismic exploration of these hazardous environments to continue. Diebold, J. M., M. Tolstoy, L. Doermann, S. Nooner, S. Webb, and T. J. Crone (2010) R/V Marcus G. Langseth Seismic Source: Modeling and Calibration. Geochemistry, Geophysics, Geosystems, 11, Q12012, doi:10.1029/2010GC003216.

  2. Theoretical study of the voltage and concentration dependence of the anomalous mole fraction effect in single calcium channels. New insights into the characterization of multi-ion channels.

    PubMed Central

    Campbell, D L; Rasmusson, R L; Strauss, H C

    1988-01-01

    Several recent independent studies on macroscopic Ca currents have demonstrated the anomalous mole fraction effect in mixtures of Ca and Ba at concentrations of 10 mM or less. Recently, Hess and Tsien (1984; Nature 309) proposed a dual binding site model, based upon Eyring rate theory, to account for this effect in L-type cardiac Ca channels. This model predicts that the anomalous mole fraction effect can be accounted for solely in terms of open single channel permeation properties; it was able to adequately reproduce the effect for macroscopic Ca currents recorded in 10 mM solutions. However, the electrochemical gradients under which single Ca channel current recordings are routinely made with the patch clamp technique vary dramatically from those used for macroscopic Ca currents. To properly assess the general validity of the Hess and Tsien model at the single Ca channel level, the effects of both large electrical potentials and elevated divalent concentrations must be understood. Computer simulations were therefore carried out using the original parameters used by Hess and Tsien under conditions designed to mimic those used in patch clamp studies. The permeation behavior generated by this model is quite complex. In particular, hyperpolarization and increased divalent concentration combine to reduce and ultimately abolish the anomalous mole fraction effect. It may therefore be very difficult to observe the anomalous mole fraction effect at the single Ca channel level; the dual-site model displays a relationship between current and mole fraction generally associated with a single-site model under the conditions frequently employed to resolve single Ca channel activity. Nonetheless, analysis of such monotonic mole fraction behavior can still be used as a test for the general validity of the dual-site model. Apparent Kms for Ca and Ba can be extracted from such monotonic behavior, and may not only be functions of membrane potential but may also depend upon the total

  3. A multi-channel low-power system-on-chip for single-unit recording and narrowband wireless transmission of neural signal.

    PubMed

    Bonfanti, A; Ceravolo, M; Zambra, G; Gusmeroli, R; Spinelli, A S; Lacaita, A L; Angotzi, G N; Baranauskas, G; Fadiga, L

    2010-01-01

    This paper reports a multi-channel neural recording system-on-chip (SoC) with digital data compression and wireless telemetry. The circuit consists of a 16 amplifiers, an analog time division multiplexer, an 8-bit SAR AD converter, a digital signal processor (DSP) and a wireless narrowband 400-MHz binary FSK transmitter. Even though only 16 amplifiers are present in our current die version, the whole system is designed to work with 64 channels demonstrating the feasibility of a digital processing and narrowband wireless transmission of 64 neural recording channels. A digital data compression, based on the detection of action potentials and storage of correspondent waveforms, allows the use of a 1.25-Mbit/s binary FSK wireless transmission. This moderate bit-rate and a low frequency deviation, Manchester-coded modulation are crucial for exploiting a narrowband wireless link and an efficient embeddable antenna. The chip is realized in a 0.35- εm CMOS process with a power consumption of 105 εW per channel (269 εW per channel with an extended transmission range of 4 m) and an area of 3.1 × 2.7 mm(2). The transmitted signal is captured by a digital TV tuner and demodulated by a wideband phase-locked loop (PLL), and then sent to a PC via an FPGA module. The system has been tested for electrical specifications and its functionality verified in in-vivo neural recording experiments. PMID:21096380

  4. Simulation Model for DVB-SH Systems Based on OFDM for Analyzing Quasi-error-free Communication over Different Channel Models

    NASA Astrophysics Data System (ADS)

    Bačić, Iva; Malarić, Krešimir; Dumić, Emil

    2014-05-01

    Mobile users today expect wide range of multimedia services to be available in different mobility scenarios, and among the others is mobile TV service. The Digital Video Broadcasting - Satellite services to Handheld (DVB-SH) is designed to provide mobile TV services, supporting a wide range of mobile multimedia services, like audio and data broadcasting as well as file downloading services. In this paper we present our simulation model for the performance evaluation of the DVB-SH system following the ETSI standard EN 302 583. Simulation model includes complete DVB-SH system, supporting all standardized system modes and parameters. From transmitter to receiver, the information may be sent over different channel models, thus simulating real case scenarios. To the best of authors' knowledge, this is the first complete model of DVB-SH system that includes all standardized system parameters and may be used for examining real DVB-SH communication as well as for educational purposes.

  5. Fracture Fabrication of a Multi-scale, Channel Device that Efficiently Captures and Linearizes DNA from Dilute Solutions

    PubMed Central

    Kim, Byoung Choul; Weerappuli, Priyan; Thouless; Takayama, Shuichi

    2015-01-01

    This paper describes a simple technique for patterning channels on elastomeric substrates, at two distinct scales of depth, through the use of controlled fracture. Control of channel depth is achieved by the careful use of different layers of PDMS, where the thickness and material properties of each layer, and the position of layers relative to one another, dictate the depth of the channels formed. The system created in this work consists of a single ‘deep’ channel, whose width can be adjusted between the micron- and nano-scale by the controlled application or removal of a uniaxial strain, and an array of ‘shallow’ nano-scale channels oriented perpendicular to the ‘deep’ channel. The utility of this system is demonstrated through the successful capture and linearization of DNA from a dilute solution, by executing a two-step ‘concentrate-then-linearize’ procedure. When the ‘deep’ channel is in its open state, and a voltage is applied across the channel network, an overlapping electric double layer forms within the ‘shallow’ channel array. This overlapping electric double layer is used to prevent passage of DNA into the ‘shallow’ channels when the DNA molecules migrate into the junctional region by electrophoresis. Release of the applied strain then allows the ‘deep’ channel to return to its closed state, reducing the cross-sectional area of this channel from the micro- to the nano-scale. The resulting hydrodynamic flow and nano-confinement effects then combine to efficiently uncoil and trap the DNA in its linearized form. By adopting this strategy, we were able to overcome the entropic barriers associated with capturing and linearizing DNA derived from a dilute solution. PMID:25589471

  6. The detection and location of low magnitude earthquakes in northern Norway using multi-channel waveform correlation at regional distances

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Bøttger Sørensen, Mathilde; Harris, David B.; Ringdal, Frode

    2007-03-01

    A fortuitous sequence of closely spaced earthquakes in the Rana region of northern Norway, during 2005, has provided an ideal natural laboratory for investigating event detectability using waveform correlation over networks and arrays at regional distances. A small number of events between magnitude 2.0 and 3.5 were recorded with a high SNR by the Fennoscandian IMS seismic arrays at distances over 600 km and three of these events, including the largest on 24 June, displayed remarkable waveform similarity even at relatively high frequencies. In an effort to detect occurrences of smaller earthquakes in the immediate geographical vicinity of the 24 June event, a multi-channel correlation detector for the NORSAR array was run for the whole calender year 2005 using the signal from the master event as a template. A total of 32 detections were made and all but 2 of these coincided with independent correlation detections using the other Nordic IMS array stations; very few correspond to signals detectable using traditional energy detectors. Permanent and temporary stations of the Norwegian National Seismic Network (NNSN) at far closer epicentral distances have confirmed that all but one of the correlation detections at NORSAR in fact correspond to real events. The closest stations at distances of approximately 10 km can confirm that the smallest of these events have magnitudes down to 0.5 which represents a detection threshold reduction of over 1.5 for the large-aperture NORSAR array and over 1.0 for the almost equidistant regional ARCES array. The incompleteness of the local network recordings precludes a comprehensive double-difference location for the full set of events. However, stable double-difference relative locations can be obtained for eight of the events using only the Lg phase recorded at the array stations. All events appear to be separated by less than 0.5 km. Clear peaks were observed in the NORSAR correlation coefficient traces during the coda of some of the

  7. The origin and evolution of a southern Patagonian lake based on multi-channel seismic reflection methods

    NASA Astrophysics Data System (ADS)

    Beres, M.; Gilli, A.; Ariztegui, D.; Anselmetti, F. S.

    2003-04-01

    As part of an ongoing study of interhemispheric correlations in climate change, 65^o km of multi-channel seismic reflection profiles were recorded with an air-gun source in the closed lake system of Lago Cardiel, Argentina (49^oS). Previous studies, using 3.5-kHz echo-sounder data, revealed six major seismic sequences throughout the lake's subsurface. Calibration of these earlier data with the dated piston-core samples permitted the reconstruction of lake levels since the late Pleistocene. The intent of using the stronger seismic source in this study was to concentrate on the deepest seismic units, Sequences V and VI, which may hold records of Pleistocene climatic conditions as well as information about the origin of the lake. Sequence VI is the oldest unit and underlies the entire lake basin. It has a parallel to wavy reflection pattern with km-scale fold wavelengths and a maximum dip of 3^o. The upper sequence boundary of Sequence VI is strongly reflective and highly irregular. A small depression, about 1 km wide and 2 km long, characterizes its deepest portion, which is over 160 ms (˜120 m) beneath the lake surface. This depression is slightly west of the lake center and oriented NNE. Sequence V unconformably overlies Sequence VI, and its extent is limited to the western part of the lake basin. It is irregular in shape and largely transparent to seismic waves, but its few internal reflections indicate an eastward progradation. The maximum thickness of Sequence V, 47 ms (˜35 m), occurs approximately in the center of the depression. Outcrops around the lake help to interpret Sequence VI as Cretaceous-Tertiary marls. Both the outcrops and the seismic profiles show fold axes that primarily strike north-south, thus indicating a generally east-west orientation of tectonic compression. Although Tertiary volcanism is widespread in the region, the nature and continuity of Sequence VI beneath the lake do not point to volcanic or impact-related origin of the lake. The

  8. Analysis of Faulting and Sediment Velocity Characteristics Outboard of the Cascadia Deformation Front from Multi-Channel Seismic Data.

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Carbotte, S. M.; Han, S.; Nedimovic, M. R.; Canales, J. P.; Carton, H. D.

    2014-12-01

    Faulting of the sediment section on the downgoing Juan de Fuca Plate (JdF) outboard of the Cascadia deformation front is explored using multi-channel seismic (MCS) data collected in 2012 during the JdF Ridge to Trench Survey (MGL1211). MCS data were collected along two full plate transects ("Oregon" (ORT) and "Washington" (WAT)) and one trench parallel line. Sediment velocity analysis is conducted via semblance spectrums on common mid-point super gathers spaced at a 625 m interval. Higher sediment velocities are found in the north, which may reflect the regional differences in sediment composition evident in existing drill holes located along our transects (DSDP site 174 - ORT and ODP site 1027 - WAT) that indicate higher smectite content along the ORT (bulk composition +44%). Accordingly, observations of fault frequency, dip, and throw along both transects show significant differences in faulting characteristics across the JdF plate. Faulting extends ~175 km (8.2 - 1.9 Ma plate age) from the deformation front along the WAT, and reaches a maximum fault density of ~0.48 fault/km in the region between 25 - 113 km (7.5 - 4 Ma plate age). Evidence of faulting extends ~300 km (8.9 - 2.6 Ma plate age) from the deformation front along the ORT and reaches a similar high fault density of ~0.48 fault/km in the region between 113 - 138 km (7.07 - 5.96 Ma plate age). Analysis of fault offset indicates growth faults along both transects. Along the ORT, maximum fault throws remain ~uniform at 10 - 15 m for crustal ages of 7.07 - 5.96 Ma and beginning ~75 km from the deformation front increase landward to maximum throws of 30 m, consistent with increasing fault strain due to flexural bending of the downgoing plate. In contrast, along the WAT, there is no evidence of increasing fault throw toward the deformation front. High fault dips (45 - 70°) are found in the region of highest fault density on both transects. Lower dips (35 - 60°) are measured in the region of increasing

  9. Multi-channel seismic reflection measurements in the Eurasian Basin, Arctic Ocean, from U.S. ice station Fram-IV

    NASA Astrophysics Data System (ADS)

    Kristoffersen, Yngve; Husebye, Eystein S.

    1985-04-01

    We present the first multi-channel seismic reflection data ever collected from the Eurasian Basin of the Arctic Ocean. The 200 km data set was acquired by a 20 channel sonobuoy array deployed at U.S. ice drift station FRAM-IV and operated for 34 days about 370 km north of Svalbard in April-May 1982. Cross array drift and ice floe rotation which may constitute the most serious obstacle to the advantage of multi-channel data acquisition did only occur to a minor degree during the experiment and render most of the data set suitable for processing using common mid-point binning. A 0.7-1.4 s (two-way traveltime) thick sedimentary section has been deposited over oceanic crust of mid-Oligocene age below the Barents Abyssal Plain. In the deepest part, sediments are infilling topographic lows which indicate predominantly turbidite deposition. Erosional truncations are only locally present in the central part of the section. Conformable bedforms deposited over gentle basement highs indicate a relatively stable bottom current regime since mid-Oligocene time. Thus the establishment of a deep water connection between the Arctic Ocean and lower latitude water masses appear to have had only minor effect on Eurasian Basin bottom current circulation. Extensive submarine slide scars on the north slope of Yermak Plateau show that mass waste have been a sediment source to the Barents Abyssal Plain.

  10. RF/microwave system high-fidelity modeling and simulation: application to airborne multi-channel receiver system for angle of arrival estimation

    NASA Astrophysics Data System (ADS)

    Wu, Chen; Rajan, Sreeraman; Young, Anne; O'Regan, Christina

    2014-06-01

    In this paper, a high-fidelity RF modeling and simulation framework is demonstrated to model an airborne multi-channel receiver system that is used to estimate the angle of arrival (AoA) of received signals from a stationary emitter. The framework is based on System Tool Kit (STK®), Matlab and SystemVue®. The SystemVue-based multi-channel receiver estimates the AoA of incoming signals using adjacent channel amplitude and phase comparisons, and it estimates the Doppler frequency shift of the aircraft by processing the transmitted and received signals. The estimated AoA and Doppler frequency are compared with the ground-truth data provided by STK to validate the efficacy of the modeling process. Unlike other current RF electronic warfare simulation frameworks, the received signal described herein is formed using the received power, the propagation delay and the transmitted waveform, and does not require information such as Doppler frequency shift or radial velocity of the moving platform from the scenario; hence, the simulation is more computationally efficient. In addition, to further reduce the overall modeling and simulation time, since the high-fidelity model computation is costly, the high-fidelity electronic system model is evoked only when the received power is higher than a predetermined threshold.

  11. Information Content Analysis for the Multi-Viewing, Multi-Channel, Multi-Polarization Imaging (3MI) Instrument : Toward Retrieval of Vertically Resolved Cloud Properties from Passive Only Measurements.

    NASA Astrophysics Data System (ADS)

    Riedi, J.; Merlin, G.; Labonnote, L.; Cornet, C.; Ferlay, N.; Desmons, M.; Dubuisson, P.; Parol, F.; Davis, A. B.; Marbach, T.

    2014-12-01

    The EUMETSAT Polar System- Second Generation (EPS-SG) is currently under development to take over the current EUMETSAT Polar System at the 2020 horizon. As part of it, the Multi-Viewing Multi-Channel Multi-Polarization Imaging mission (3MI) will be dedicated to the operational monitoring of aerosols but will also provide unique observations for characterization of cloud properties building on the legacy of POLDER and particularly of its 3rd mission (PARASOL) within the A-Train. Through the synergy of POLDER3/PARASOL and MODIS/AQUA several studies have demonstrated the great interest of combining multispectral, multiangle and polarization measurements in the visible, near and shortwave infrared to better constrain retrieval of clouds microphysical and macrophysical properties. Remote-sensing of cloud thermodynamic phase (Riedi et al, 2010), liquid (Bréon and Doutriaux-Boucher, 2005) or ice clouds microphysics (Zhang et al, 2009; Cole et al, 2012), cloud radiative (Zeng et al, 2012) or macrophysical properties (Ferlay et al, 2010; Desmons et al, 2013) can unarguably benefit from the additional information content brought by polarization and multiangle measurements. At the same time, retrieval algorithms are gaining further complexity and skills. Thanks to availability of computational resources, practical implementation of optimal estimation or related optimization techniques (Delanoe & Hogan, 2008; Dubovik et al, 2013) have appeared that allow simultaneous and consistent retrieval of larger sets of parameters from constantly growing observations vectors. Therefore 3MI observations will not only allow to improve accuracy of future cloud products but also opens perspectives for the development of new retrieval algorithms. A major challenge for cloud remote-sensing from passive measurements is to obtain information on clouds properties vertical distribution and structure. Through results of a comprehensive information content analysis we will illustrate our current

  12. Insights from analyzing and modelling cascading multi-lake outburst flood events in the Santa Cruz Valley (Cordillera Blanca, Perú)

    NASA Astrophysics Data System (ADS)

    Emmer, Adam; Mergili, Martin; Juřicová, Anna; Cochachin, Alejo; Huggel, Christian

    2016-04-01

    Since the end of Little Ice Age, the Cordillera Blanca of Perú has experienced tens of lake outburst floods (LOFs), resulting in the loss of thousands of lives and significant material damages. Most commonly involving glacial lakes, such events are often directly or indirectly related to glacier retreat. Here we analyze an event on 8th February 2012 involving four lakes and affecting two valleys (Santa Cruz and Artizón) in the northern part of the Cordillera Blanca. Using the combination of field data, satellite images, digital elevation model (DEM) and GIS-based modelling approaches, the main objectives are: (i) to better understand complex multi-lake outburst flood and related foregoing and induced geomorphological processes; and (ii) to evaluate and discuss the suitability, potentials and limitations of the r.avaflow model for modelling such complex process chains. Analyzing field geomorphological evidence and remotely-sensed images, we reconstruct the event as follows: a landslide from the recently deglaciated left lateral moraine of Lake Artizón Alto (4 639 m a.s.l.), characterized by steep slopes and a height of more than 200 m produced a displacement wave which overtopped the bedrock dam of the lake. The resulting flood wave breached the dam of the downstream moraine-/landslide-dammed Lake Artizón Bajo (4 477 m a.s.l.), decreasing the lake level by 10 m and releasing 3 x 105 m3 of water. Significant amounts of material were eroded from the steeper parts of the Artizón Valley (mean slope >15°) and deposited further downstream in the flatter part of the Santa Cruz Valley (mean slope <2°; confluence of the two valleys at 3 985 m a.s.l.). The flood affected two debris cone-dammed lakes (Jatuncocha and Ichiccocha) in the Santa Cruz Valley. Some minor damages to the dam of Lake Jatuncocha were documented. Geomprohological evidence of the event was observed more than 20 km downstream from Lake Artizón Alto. The described multi-LOF event was employed as a

  13. HAI: A novel airborne multi-channel hygrometer for fast multi-phase H2O quantification: Performance of the HAI instrument during the first flights on the German HALO aircraft

    NASA Astrophysics Data System (ADS)

    Buchholz, B.; Ebert, V.; Kraemer, M.; Afchine, A.

    2014-12-01

    Common gas phase H2O measurements on fast airborne platforms e.g. using backward facing or "Rosemount"-inlets can lead to a high risk of ice and droplets contamination. In addition, currently no single hygrometer exists that allows a simultaneous, high-speed measurement of all phases (gas, liquid, ice) with the same detection principle. In the rare occasions multi-phase measurements are realized, gas-and condensed-phase observations rely on different methods, instruments and calibration strategies so that precision and accuracy levels are quite difficult to quantify. This is effectively avoided by the novel TDLAS instrument, HAI, Hygrometer for Atmospheric Investigation, which allows a simultaneous, high speed, multi-phase detection without any sensor calibration in a unique "2+2" channel concept. Hai combines two independent wavelength channels, at 1.4 µm and at 2.6 µm, for a wide dynamic range from 1 to 30 000 ppmv, with a simultaneous closed path (extractive) and open path detection. Thus, "Total", i.e. gas-phase plus condensed-phase water is measured by sampling via a forward facing inlet into "closed-path" extractive cells. A selective, sampling-free, high speed gas phase detection is realized via a dual-wavelength "open-path" cell placed outside of the aircraft fuselage. All channels can be sampled with 120 Hz (measurement cycle time Dt=1.6 ms) allowing an unprecedented spatial resolution of 30 cm at 900 km/h. The evaluation of the individual multi-channel raw-data is done post flight, without any channel interdependencies, in calibration-free mode, thus allowing fast, accurate and precise multi-phase water detection in flight. The performance could be shown in more than 200 net flights hours in three scientific flight campaigns (TACTS, ESMVal, ML-CIRRUS) on the new German HALO aircraft. In addition the level of the accuracy of the calibration free evaluation was evaluated at the German national primary water vapor standard.

  14. Multi-scaled normal mode analysis method for dynamics simulation of protein-membrane complexes: A case study of potassium channel gating motion correlations

    SciTech Connect

    Wu, Xiaokun; Han, Min; Ming, Dengming

    2015-10-07

    Membrane proteins play critically important roles in many cellular activities such as ions and small molecule transportation, signal recognition, and transduction. In order to fulfill their functions, these proteins must be placed in different membrane environments and a variety of protein-lipid interactions may affect the behavior of these proteins. One of the key effects of protein-lipid interactions is their ability to change the dynamics status of membrane proteins, thus adjusting their functions. Here, we present a multi-scaled normal mode analysis (mNMA) method to study the dynamics perturbation to the membrane proteins imposed by lipid bi-layer membrane fluctuations. In mNMA, channel proteins are simulated at all-atom level while the membrane is described with a coarse-grained model. mNMA calculations clearly show that channel gating motion can tightly couple with a variety of membrane deformations, including bending and twisting. We then examined bi-channel systems where two channels were separated with different distances. From mNMA calculations, we observed both positive and negative gating correlations between two neighboring channels, and the correlation has a maximum as the channel center-to-center distance is close to 2.5 times of their diameter. This distance is larger than recently found maximum attraction distance between two proteins embedded in membrane which is 1.5 times of the protein size, indicating that membrane fluctuation might impose collective motions among proteins within a larger area. The hybrid resolution feature in mNMA provides atomic dynamics information for key components in the system without costing much computer resource. We expect it to be a conventional simulation tool for ordinary laboratories to study the dynamics of very complicated biological assemblies. The source code is available upon request to the authors.

  15. Multi-scaled normal mode analysis method for dynamics simulation of protein-membrane complexes: A case study of potassium channel gating motion correlations

    NASA Astrophysics Data System (ADS)

    Wu, Xiaokun; Han, Min; Ming, Dengming

    2015-10-01

    Membrane proteins play critically important roles in many cellular activities such as ions and small molecule transportation, signal recognition, and transduction. In order to fulfill their functions, these proteins must be placed in different membrane environments and a variety of protein-lipid interactions may affect the behavior of these proteins. One of the key effects of protein-lipid interactions is their ability to change the dynamics status of membrane proteins, thus adjusting their functions. Here, we present a multi-scaled normal mode analysis (mNMA) method to study the dynamics perturbation to the membrane proteins imposed by lipid bi-layer membrane fluctuations. In mNMA, channel proteins are simulated at all-atom level while the membrane is described with a coarse-grained model. mNMA calculations clearly show that channel gating motion can tightly couple with a variety of membrane deformations, including bending and twisting. We then examined bi-channel systems where two channels were separated with different distances. From mNMA calculations, we observed both positive and negative gating correlations between two neighboring channels, and the correlation has a maximum as the channel center-to-center distance is close to 2.5 times of their diameter. This distance is larger than recently found maximum attraction distance between two proteins embedded in membrane which is 1.5 times of the protein size, indicating that membrane fluctuation might impose collective motions among proteins within a larger area. The hybrid resolution feature in mNMA provides atomic dynamics information for key components in the system without costing much computer resource. We expect it to be a conventional simulation tool for ordinary laboratories to study the dynamics of very complicated biological assemblies. The source code is available upon request to the authors.

  16. Estimating channel erosion and deposition using multi-date LiDAR and orthophotography: a case study in the Browns River, Chittenden County, VT

    NASA Astrophysics Data System (ADS)

    Morrissey, L. A.; Garvey, K.; Rizzo, D.; Underwood, K.; Wemple, B. C.; Kline, M.

    2012-12-01

    Sediment is a widespread cause of stream impairment nationally and worldwide, negatively impacting water quality, channel stability, and stream health. In recent decades, attempts to limit sediment sources and closely linked phosphorus loading to and within streams and lakes by state and provincial governments have met with limited success. In addition, the demands of traditional field methods in combination with the environmental and economic costs of recent and projected extreme weather events call for innovative and cost-effective methodologies that quantify sediment sources, prioritize and target areas requiring attention at site to watershed scales, and assess the effectiveness of management programs aimed at reducing sediment loading to streams. To this end, this study integrates multi-temporal, very high spatial resolution LiDAR elevation data and digital orthophotography to map and quantify channel erosion and deposition associated with fluvial planform change at site, reach, and watershed spatial scales. In addition, we partition the contribution of streambank and channel erosion (excluding erosion and deposition below the water's surface). The study area encompasses the transitional section (23 km) of the 48 km Browns River in Chittenden County, Vermont which is representative of numerous streams throughout the Lake Champlain basin that contribute sediment and nutrients to the lake. Over a three year study period, erosion (51,575 mT) exceeded deposition (42,664 mT) by 21%. Upstream reaches dominated by low gradient slopes, gravel substrates, and high width to depth ratios experienced net deposition, while downstream reaches, dominated by deep, narrow channels with sand substrates, experienced net erosion. Transitional reaches and two reaches extensively straightened and armored exhibited little erosion or deposition. Channel and streambank erosion estimates normalized by reach length, ranged from 0.2 to 3.95 mT m-1 while normalized channel deposition

  17. Algorithms using inter-band cross-correlation for pixel registration and jitter reconstruction in multi-channel push-broom imagers

    SciTech Connect

    Theiler, J.; Henderson, B.G.; Smith, B.W.

    1997-11-01

    We present two algorithms for determining sensor motion of a multi-spectral push-broom imager for use in subsequent image registration. The first algorithm, termed the {open_quotes}pairwise{close_quotes} method, performs cross-correlations between individual pairs of channels. The offsets of maximum correlation are formulated into a system of linear equations whose solution gives an estimate of the jitter function. The second algorithm performs cross-correlations between channels and a reference image called the {open_quotes}baseline{close_quotes} which is constructed by averaging together all the channels in the image cube. An estimated jitter time series is computed for each channel, all of which are overlapped and averaged to obtain a best estimate of the jitter function. The pairwise method is more general in that it can handle a wider range of jitter scenarios. The baseline method, although more restricted, is very simple to implement, and its accuracy can be improved substantially through iteration. In this paper, we describe both methods in detail and present results of simulations performed on thermal-infrared data cubes.

  18. An Eight-Channel 400 GHz-Spacing Etched Diffraction Grating Multi/Demultiplexer on a Nanophotonic Silicon-on-Insulator Platform

    NASA Astrophysics Data System (ADS)

    Shen, Ao; Qiu, Chen; Hu, Ting; Xu, Chao; Jiang, Xiao-Qing; Li, Yu-Bo; Yang, Jian-Yi

    2013-08-01

    An eight-channel 400 GHz-spacing planar waveguide multi/demultiplexer employing etched diffraction grating is designed and fabricated on a silicon-on-insulator platform with a 220 nm thick top layer. The design parameters are optimized by scalar diffraction simulation to obtain optimal performance with a small footprint of only 0.75 mm2. A bi-level adiabatic taper is used to connect the input/output waveguide and the slab waveguide so as to reduce the insertion loss and the broadening of the diffraction angle of the propagating light. The device is fabricated in a two-step process with E-beam lithography and dry etching, and the alignment accuracy is 10 nm or even better. Measurements show that the insertion loss is 7.35 dB and the crosstalk between adjacent channels is about -15 dB. Ways to improve the performance are also investigated in detail.

  19. Multi-GHz bandpass, high-repetition rate single channel mobile diagnostic system for ultra-wideband applications

    NASA Astrophysics Data System (ADS)

    Miner, Lynn M.; Voss, Donald E.

    1993-01-01

    Characterizing radiated ultra-wideband (UWB) signals poses challenges due to requirements for (1) multi-GHz bandpass recording of the signal's leading edge; (2) GHz-bandpass recording of long record lengths (10s-100s of ns); and (3) determining shot-to-shot reproducibility at rep-rates exceeding 10 kHz. The System Verification Apparatus (SVA) is a novel diagnostic system which can measure 60-ps rise-time signals on a single-shot basis, while monitoring pulse-to-pulse variation. The fully-integrated SVA includes a broadband sensor, signal and trigger conditioning electronics, multiple parallel digitizers with deep local storge, and automated software for acquiring, archiving, and analyzing waveform data with rapid (secs-minute) turnaround time. The instruments are housed in a portable 100-dB shielded aluminum enclosure. The SVA utilizes a 6-GHz bandpass free-field D-dot sensor to measure the incident electric field. Three separate digitizers together meet the requirements of high bandwidth, long record length, and high repetition rate. A 6-GHz bandpass scan converter digitizer captures the leading edge (few ns) of the radiated signal. 1-GHz and 600 MHz bandwidth solid-state digitizers supporting long record lengths (greater than 2 micrometers) record the balance of the signal, which typically contains negligible content above 1 GHz. These solid-state digitizers can store greater than 900 waveforms locally at rep-rates exceeding 65 Hz and 100 kHz, respectively. Data management and instrument control use an 80486-based PC, operating in a user-friendly Windows environment. All waveform and system configuration data are automatically stored in a built-in database. A fiber-optic link, up to 2 km long, provides electromagnetic isolation of the computer.

  20. New Method for Accurate Calibration of Micro-Channel Plate based Detection Systems and its use in the Fast Plasma Investigation of NASA's Magnetospheric MultiScale Mission

    NASA Astrophysics Data System (ADS)

    Gliese, U.; Avanov, L. A.; Barrie, A.; Kujawski, J. T.; Mariano, A. J.; Tucker, C. J.; Chornay, D. J.; Cao, N. T.; Zeuch, M.; Pollock, C. J.; Jacques, A. D.

    2013-12-01

    The Fast Plasma Investigation (FPI) of the NASA Magnetospheric MultiScale (MMS) mission employs 16 Dual Electron Spectrometers (DESs) and 16 Dual Ion Spectrometers (DISs) with 4 of each type on each of 4 spacecraft to enable fast (30ms for electrons; 150ms for ions) and spatially differentiated measurements of full the 3D particle velocity distributions. This approach presents a new and challenging aspect to the calibration and operation of these instruments on ground and in flight. The response uniformity and reliability of their calibration and the approach to handling any temporal evolution of these calibrated characteristics all assume enhanced importance in this application, where we attempt to understand the meaning of particle distributions within the ion and electron diffusion regions. Traditionally, the micro-channel plate (MCP) based detection systems for electrostatic particle spectrometers have been calibrated by setting a fixed detection threshold and, subsequently, measuring a detection system count rate plateau curve to determine the MCP voltage that ensures the count rate has reached a constant value independent of further variation in the MCP voltage. This is achieved when most of the MCP pulse height distribution (PHD) is located at higher values (larger pulses) than the detection amplifier threshold. This method is adequate in single-channel detection systems and in multi-channel detection systems with very low crosstalk between channels. However, in dense multi-channel systems, it can be inadequate. Furthermore, it fails to fully and individually characterize each of the fundamental parameters of the detection system. We present a new detection system calibration method that enables accurate and repeatable measurement and calibration of MCP gain, MCP efficiency, signal loss due to variation in gain and efficiency, crosstalk from effects both above and below the MCP, noise margin, and stability margin in one single measurement. The fundamental

  1. Design of a dual-channel multi-mode GNSS receiver with a Σ Δ fractional-N synthesizer

    NASA Astrophysics Data System (ADS)

    Qiang, Long; Yiqi, Zhuang; Yue, Yin; Le, Li; Jin, Wang; Zhenrong, Li; Qiankun, Liu; Lei, Wang

    2012-11-01

    A 72 mW highly integrated dual-channel multimode GNSS (global navigation satellite system) receiver with a Σ Δ fractional-N synthesizer which covers GPS L1 and the Compass B1/B2/B3 band is presented. This chip was fabricated in a TSMC CMOS 0.18 μm process and packaged in a 48-pin 3 × 3 mm2 land grid array chip scale package. This work achieves NF <= 5.3 dB without an external LNA, channel gain = 105 dB for channel one (Compass B2 and B3 band), and channel gain = 110 dB for channel two (GPS L1 and Compass B1 band). Image rejection (IMRR) = 36 dB, phase noise is -115.9 dBc @ 1 MHz and -108.9 dBc @ 1 MHz offset from the carrier for the two channels separately. At the low power consumption, multibands of GNSS are compatible in one chip, which is easy for consumers to use, when two different navigation signals are received simultaneously.

  2. Frontal and right temporal activations correlate negatively with depression severity during verbal fluency task: a multi-channel near-infrared spectroscopy study.

    PubMed

    Noda, Takamasa; Yoshida, Sumiko; Matsuda, Taro; Okamoto, Nagahisa; Sakamoto, Kota; Koseki, Shunsuke; Numachi, Yotaro; Matsushima, Eisuke; Kunugi, Hiroshi; Higuchi, Teruhiko

    2012-07-01

    Multi-channel near-infrared spectroscopy (NIRS) is a noninvasive, on-the-spot, functional neuroimaging technique allowing detection of the spatiotemporal characteristics of brain activity. Previous NIRS studies indicated the oxy-hemoglobin (oxy-Hb) increase during a verbal fluency task (VFT) is attenuated in patients with major depressive disorder (MDD) as compared with healthy controls. However, the possible relationship between depression symptom severity and oxy-Hb change on NIRS has not yet been elucidated. To examine this relationship, we recruited 30 patients with MDD and 30 age-, gender- and intelligence quotient-matched controls. All underwent NIRS during VFT. As expected, the oxy-Hb increase during the task was significantly smaller in patients than in controls. After false discovery rate correction using 31 channels, the mean increase in oxy-Hb during the task showed a significant negative correlation with the total score of the Hamilton Rating Scale for Depression 21-item version (ch25: rho = -.56; FDR-corrected p: .001). When each item of the HAM-D21 was examined individually, insomnia early in 9 channels (rho = -.63 to -.46; FDR corrected p: .000-.014), work and activity in 2 channels (rho = -.61 to -.57; FDR corrected p: .001 to .003) and psychomotor retardation in 12 channels (rho = -.70 to -.44; FDR corrected p: .000-.018) showed significant negative correlations with the mean oxy-Hb increase in the right frontal temporal region. Although it is possible that our results were affected by medication, these data suggest reduced right frontal temporal activation on NIRS during VFT is related to the symptom severity of MDD. PMID:22572569

  3. A complete look at the multi-channel dissociation of propenal photoexcited at 193 nm: branching ratios and distributions of kinetic energy.

    PubMed

    Chaudhuri, Chanchal; Lee, Shih-Huang

    2011-04-28

    We observed fifteen photofragments upon photolysis of propenal (acrolein, CH(2)CHCHO) at 193 nm using photofragment translational spectroscopy and selective vacuum-ultraviolet (VUV) photoionization. All the photoproducts arise from nine primary and two secondary dissociation pathways. We measured distributions of kinetic energy of products and determined branching ratios of dissociation channels. Dissociation to CH(2)CHCO + H and CH(2)CH + HCO are two major primary channels with equivalent branching ratios of 33%. The CH(2)CHCO fragment spontaneously decomposes to CH(2)CH + CO. A proportion of primary products CH(2)CH from the fission of bond C-C of propenal further decompose to CHCH + H but secondary dissociation HCO → H + CO is negligibly small. Binary dissociation to CH(2)CH(2) (or CH(3)CH) + CO and concerted three-body dissociation to C(2)H(2) + CO + H(2) have equivalent branching ratios of 14%-15%. The other channels have individual branching ratios of ∼1%. The production of HCCO + CH(3) indicates the formation of intermediate methyl ketene (CH(3)CHCO) and the production of CH(2)CCH + OH and CH(2)CC + H(2)O indicate the formation of intermediate hydroxyl propadiene (CH(2)CCHOH) from isomerization of propenal. Distributions of kinetic energy release and dissociation mechanisms are discussed. This work provides a complete look and profound insight into the multi-channel dissociation mechanisms of propenal. The combination of a molecular beam apparatus and synchrotron VUV ionization allowed us to untangle the complex mechanisms of nine primary and two secondary dissociation channels. PMID:21423979

  4. Development of a front-end analog circuit for multi-channel SiPM readout and performance verification for various PET detector designs

    NASA Astrophysics Data System (ADS)

    Ko, Guen Bae; Yoon, Hyun Suk; Kwon, Sun Il; Lee, Chan Mi; Ito, Mikiko; Hong, Seong Jong; Lee, Dong Soo; Lee, Jae Sung

    2013-03-01

    Silicon photomultipliers (SiPMs) are outstanding photosensors for the development of compact imaging devices and hybrid imaging systems such as positron emission tomography (PET)/ magnetic resonance (MR) scanners because of their small size and MR compatibility. The wide use of this sensor for various types of scintillation detector modules is being accelerated by recent developments in tileable multichannel SiPM arrays. In this work, we present the development of a front-end readout module for multi-channel SiPMs. This readout module is easily extendable to yield a wider detection area by the use of a resistive charge division network (RCN). We applied this readout module to various PET detectors designed for use in small animal PET/MR, optical fiber PET/MR, and double layer depth of interaction (DOI) PET. The basic characteristics of these detector modules were also investigated. The results demonstrate that the PET block detectors developed using the readout module and tileable multi-channel SiPMs had reasonable performance.

  5. Calcium isotope enrichment by means of multi-channel counter-current electrophoresis for the study of particle and nuclear physics

    NASA Astrophysics Data System (ADS)

    Kishimoto, T.; Matsuoka, K.; Fukumoto, T.; Umehara, S.

    2015-03-01

    We have developed a new method for enrichment of large amounts of calcium isotopes for the future study of ^{48}Ca double beta decay. The method is called multi-channel counter-current electrophoresis (MCCCE). We present the concept of MCCCE, in which the power density in the migration path is the key to efficient enrichment of a large amount of materials. In MCCCE, ions migrate in multi-channels on a boron nitride (BN) plate, allowing a substantial increase in the power density to be achieved. We made a tiny prototype instrument and obtained an enrichment factor of 3 for the ratio of the abundance of ^{48}Ca to ^{43}Ca over that of natural abundance. This corresponds to an enrichment factor of 6 for ^{48}Ca to ^{40}Ca. This remarkably large enrichment factor demonstrates that MCCCE is a realistic and promising method for the enrichment of large amounts of ions. It can be applied to many other elements and compounds.

  6. Linear and nonlinear analyses of multi-channel mechanomyographic recordings reveal heterogeneous activation of wrist extensors in presence of delayed onset muscle soreness.

    PubMed

    Madeleine, Pascal; Hansen, Ernst A; Samani, Afshin

    2014-12-01

    In this study, we applied multi-channel mechanomyographic (MMG) recordings in combination with linear and nonlinear analyses to investigate muscular and musculotendinous effects of high intensity eccentric exercise. Twelve accelerometers arranged in a 3 × 4 matrix over the dominant elbow muscles were used to detect MMG activity in 12 healthy participants. Delayed onset muscle soreness was induced by repetitive high intensity eccentric contractions of the wrist extensor muscles. Average rectified values (ARV) as well as percentage of recurrence (%REC) and percentage of determinism (%DET) extracted from recurrence quantification analysis were computed from data obtained during static-dynamic contractions performed before exercise, immediately after exercise, and in presence of muscle soreness. A linear mixed model was used for the statistical analysis. The ARV, %REC, and %DET maps revealed heterogeneous MMG activity over the wrist extensor muscles before, immediately after, and in presence of muscle soreness (P<0.01). The ARVs were higher while the %REC and %DET were lower in presence of muscle soreness compared with before exercise (P<0.05). The study provides new key information on linear and nonlinear analyses of multi-channel MMG recordings of the wrist extensor muscles following eccentric exercise that results in muscle soreness. Recurrence quantification analysis can be suggested as a tool for detection of MMG changes in presence of muscle soreness. PMID:25277830

  7. Optimization and Parallelization of the Thermal-Hydraulic Sub-channel Code CTF for High-Fidelity Multi-physics Applications

    SciTech Connect

    Salko, Robert K; Schmidt, Rodney; Avramova, Maria N

    2014-01-01

    This paper describes major improvements to the computational infrastructure of the CTF sub-channel code so that full-core sub-channel-resolved simulations can now be performed in much shorter run-times, either in stand-alone mode or as part of coupled-code multi-physics calculations. These improvements support the goals of the Department Of Energy (DOE) Consortium for Advanced Simulations of Light Water (CASL) Energy Innovation Hub to develop high fidelity multi-physics simulation tools for nuclear energy design and analysis. A set of serial code optimizations--including fixing computational inefficiencies, optimizing the numerical approach, and making smarter data storage choices--are first described and shown to reduce both execution time and memory usage by about a factor of ten. Next, a Single Program Multiple Data (SPMD) parallelization strategy targeting distributed memory Multiple Instruction Multiple Data (MIMD) platforms and utilizing domain-decomposition is presented. In this approach, data communication between processors is accomplished by inserting standard MPI calls at strategic points in the code. The domain decomposition approach implemented assigns one MPI process to each fuel assembly, with each domain being represented by its own CTF input file. The creation of CTF input files, both for serial and parallel runs, is also fully automated through use of a pre-processor utility that takes a greatly reduced set of user input over the traditional CTF input file. To run CTF in parallel, two additional libraries are currently needed; MPI, for inter-processor message passing, and the Parallel Extensible Toolkit for Scientific Computation (PETSc), which is leveraged to solve the global pressure matrix in parallel. Results presented include a set of testing and verification calculations and performance tests assessing parallel scaling characteristics up to a full core, sub-channel-resolved model of Watts Bar Unit 1 under hot full-power conditions (193 17x17

  8. Adaptation of a cubic smoothing spline algortihm for multi-channel data stitching at the National Ignition Facility

    SciTech Connect

    Brown, C; Adcock, A; Azevedo, S; Liebman, J; Bond, E

    2010-12-28

    Some diagnostics at the National Ignition Facility (NIF), including the Gamma Reaction History (GRH) diagnostic, require multiple channels of data to achieve the required dynamic range. These channels need to be stitched together into a single time series, and they may have non-uniform and redundant time samples. We chose to apply the popular cubic smoothing spline technique to our stitching problem because we needed a general non-parametric method. We adapted one of the algorithms in the literature, by Hutchinson and deHoog, to our needs. The modified algorithm and the resulting code perform a cubic smoothing spline fit to multiple data channels with redundant time samples and missing data points. The data channels can have different, time-varying, zero-mean white noise characteristics. The method we employ automatically determines an optimal smoothing level by minimizing the Generalized Cross Validation (GCV) score. In order to automatically validate the smoothing level selection, the Weighted Sum-Squared Residual (WSSR) and zero-mean tests are performed on the residuals. Further, confidence intervals, both analytical and Monte Carlo, are also calculated. In this paper, we describe the derivation of our cubic smoothing spline algorithm. We outline the algorithm and test it with simulated and experimental data.

  9. Orbital angular momentum in four channel spatial domain multiplexing system for multi-terabit per second communication architectures

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.; Muralikrishnan, Hari P.; Kozaitis, Samuel P.

    2012-06-01

    Bandwidth increase has always been an important area of research in communications. A novel multiplexing technique known as Spatial Domain Multiplexing (SDM) has been developed at the Optronics Laboratory of Florida Institute of Technology to increase the bandwidth to T-bits/s range. In this technique, space inside the fiber is used effectively to transmit up to four channels of same wavelength at the same time. Experimental and theoretical analysis shows that these channels follow independent helical paths inside the fiber without interfering with each other. Multiple pigtail laser sources of exactly the same wavelength are used to launch light into a single carrier fiber in a fashion that resulting channels follow independent helical trajectories. These helically propagating light beams form optical vortices inside the fiber and carry their own Orbital Angular Momentum (OAM). The outputs of these beams appear as concentric donut shaped rings when projected on a screen. This endeavor presents the experimental outputs and simulated results for a four channel spatially multiplexed system effectively increasing the system bandwidth by a factor of four.

  10. Determination of Vitamin C in a LC/DAD Method for Analyzing Water Soluble Vitamins in Multi-Vitamin Dietary Supplements Containing Multi-Minerals (Experimental Biology, April, 2007, Washington, D.C.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have recently reported a method for the simultaneous determination of a suite of water soluble vitamins in multi-vitamin/multi-mineral dietary supplements (MV/MM) by liquid chromatography with diode array detection (1). This method provided efficient extraction and separation of the Vitamin C, b...

  11. Determination of Vitamin C in a LC/DAD Method for Analyzing Water Soluble Vitamins in Multi-Vitamin Dietary Supplements Containing Multi-Minerals (AOAC Annual Meeting, Minneapolis, MN, Sept, 2006)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have recently reported a method for the simultaneous determination by liquid chromatography with diode array detection of a suite of water soluble vitamins in multi-vitamin/multi-mineral dietary supplements (MV/MM) (1). In that work, although there was good extraction of vitamin C and good chrom...

  12. DIFFERENTIAL ANALYZER

    DOEpatents

    Sorensen, E.G.; Gordon, C.M.

    1959-02-10

    Improvements in analog eomputing machines of the class capable of evaluating differential equations, commonly termed differential analyzers, are described. In general form, the analyzer embodies a plurality of basic computer mechanisms for performing integration, multiplication, and addition, and means for directing the result of any one operation to another computer mechanism performing a further operation. In the device, numerical quantities are represented by the rotation of shafts, or the electrical equivalent of shafts.

  13. Timing Performance of a MCP Photon Detector Read Out with Multi-Channel Electronics for the Torch System

    NASA Astrophysics Data System (ADS)

    Castillo García, L.; Fopma, J. M.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.

    2014-06-01

    As part of the R&D phase of the (Time Of internally Reflected Cherenkov light) TORCH project, 8×8 pad micro-channel plate photon detectors are being characterized. Multichannel electronics based on fast amplifier discriminator and time digitization conversion ASICs are used to read out and time the charge signals from single photoelectrons. The MCP performance is investigated with a 20ps pulsed blue laser diode. A time resolution of 90ps is achieved. Timing properties are obtained at modest MCP gain, without time walk correction and no fine calibration of the time-to-digital converter circuit. The reference time is provided by a single-channel MCP photon detector coupled to a Constant Fraction Discriminator. Photoelectron detection efficiencies and back-scattering effect are discussed together with the laser source influence on the timing performance.

  14. Efficient Remote Preparation of Four-Qubit Cluster-Type Entangled States with Multi-Party Over Partially Entangled Channels

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Hoehn, Ross D.; Ye, Liu; Kais, Sabre

    2016-03-01

    We present a strategy for realizing multiparty-controlled remote state preparation (MCRSP) for a family of four-qubit cluster-type states by taking a pair of partial entanglements as the quantum channels. In this scenario, the encoded information is transmitted from the sender to a spatially separated receiver with control of the transmission by multiple parties. Predicated on the collaboration of all participants, the desired state can be faithfully restored at the receiver's location with high success probability by application of additional appropriate local operations and necessary classical communication. Moreover, this proposal for MCRSP can be faithfully achieved with unit total success probability when the quantum channels are distilled to maximally entangled ones.

  15. Efficient Remote Preparation of Four-Qubit Cluster-Type Entangled States with Multi-Party Over Partially Entangled Channels

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Hoehn, Ross D.; Ye, Liu; Kais, Sabre

    2016-07-01

    We present a strategy for realizing multiparty-controlled remote state preparation (MCRSP) for a family of four-qubit cluster-type states by taking a pair of partial entanglements as the quantum channels. In this scenario, the encoded information is transmitted from the sender to a spatially separated receiver with control of the transmission by multiple parties. Predicated on the collaboration of all participants, the desired state can be faithfully restored at the receiver's location with high success probability by application of additional appropriate local operations and necessary classical communication. Moreover, this proposal for MCRSP can be faithfully achieved with unit total success probability when the quantum channels are distilled to maximally entangled ones.

  16. Implementation of a real-time multi-channel gateway server in ubiquitous integrated biotelemetry system for emergency care (UIBSEC).

    PubMed

    Cheon, Gyeongwoo; Shin, Il Hyung; Jung, Min Yang; Kim, Hee Chan

    2009-01-01

    We developed a gateway server to support various types of bio-signal monitoring devices for ubiquitous emergency healthcare in a reliable, effective, and scalable way. The server provides multiple channels supporting real-time N-to-N client connections. We applied our system to four types of health monitoring devices including a 12-channel electrocardiograph (ECG), oxygen saturation (SpO(2)), and medical imaging devices (a ultrasonograph and a digital skin microscope). Different types of telecommunication networks were tested: WIBRO, CDMA, wireless LAN, and wired internet. We measured the performance of our system in terms of the transmission rate and the number of simultaneous connections. The results show that the proposed network communication strategy can be successfully applied to the ubiquitous emergency healthcare service by providing a fast rate enough for real-time video transmission and multiple connections among patients and medical personnel. PMID:19964662

  17. Gas Analyzer

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The M200 originated in the 1970's under an Ames Research Center/Stanford University contract to develop a small, lightweight gas analyzer for Viking Landers. Although the unit was not used on the spacecraft, it was further developed by The National Institute for Occupational Safety and Health (NIOSH). Three researchers from the project later formed Microsensor Technology, Inc. (MTI) to commercialize the analyzer. The original version (Micromonitor 500) was introduced in 1982, and the M200 in 1988. The M200, a more advanced version, features dual gas chromatograph which separate a gaseous mixture into components and measure concentrations of each gas. It is useful for monitoring gas leaks, chemical spills, etc. Many analyses are completed in less than 30 seconds, and a wide range of mixtures can be analyzed.

  18. Process Analyzer

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The ChemScan UV-6100 is a spectrometry system originally developed by Biotronics Technologies, Inc. under a Small Business Innovation Research (SBIR) contract. It is marketed to the water and wastewater treatment industries, replacing "grab sampling" with on-line data collection. It analyzes the light absorbance characteristics of a water sample, simultaneously detects hundreds of individual wavelengths absorbed by chemical substances in a process solution, and quantifies the information. Spectral data is then processed by ChemScan analyzer and compared with calibration files in the system's memory in order to calculate concentrations of chemical substances that cause UV light absorbance in specific patterns. Monitored substances can be analyzed for quality and quantity. Applications include detection of a variety of substances, and the information provided enables an operator to control a process more efficiently.

  19. Telephone use by a multi-channel cochlear implant patient. An evaluation using open-set CID sentences.

    PubMed

    Brown, A M; Clark, G M; Dowell, R C; Martin, L F; Seligman, P M

    1985-03-01

    A totally deaf person with a multiple-channel cochlear prosthesis obtained open-set speech discrimination using the telephone. CID Everyday Sentences were presented by telephone to the patient, who repeated an average of 21 per cent of key words correctly on the first presentation, and 47 per cent when a repeat of the sentences was permitted. This result is consistent with the patient's reports of telephone usage. PMID:3838331

  20. A multi-channel gel electrophoresis and continuous fraction collection apparatus for high throughput protein separation and characterization

    SciTech Connect

    Choi, Megan; Nordmeyer, Robert A.; Cornell, Earl; Dong, Ming; Biggin, Mark D.; Jin, Jian

    2009-10-02

    To facilitate a direct interface between protein separation by PAGE and protein identification by mass spectrometry, we developed a multichannel system that continuously collects fractions as protein bands migrate off the bottom of gel electrophoresis columns. The device was constructed using several short linear gel columns, each of a different percent acrylamide, to achieve a separation power similar to that of a long gradient gel. A Counter Free-Flow elution technique then allows continuous and simultaneous fraction collection from multiple channels at low cost. We demonstrate that rapid, high-resolution separation of a complex protein mixture can be achieved on this system using SDS-PAGE. In a 2.5 h electrophoresis run, for example, each sample was separated and eluted into 48-96 fractions over a mass range of 10-150 kDa; sample recovery rates were 50percent or higher; each channel was loaded with up to 0.3 mg of protein in 0.4 mL; and a purified band was eluted in two to three fractions (200 L/fraction). Similar results were obtained when running native gel electrophoresis, but protein aggregation limited the loading capacity to about 50 g per channel and reduced resolution.