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Sample records for digitally synthesized high

  1. Hardware Implementation of 32-Bit High-Speed Direct Digital Frequency Synthesizer

    PubMed Central

    Ibrahim, Salah Hasan; Ali, Sawal Hamid Md.; Islam, Md. Shabiul

    2014-01-01

    The design and implementation of a high-speed direct digital frequency synthesizer are presented. A modified Brent-Kung parallel adder is combined with pipelining technique to improve the speed of the system. A gated clock technique is proposed to reduce the number of registers in the phase accumulator design. The quarter wave symmetry technique is used to store only one quarter of the sine wave. The ROM lookup table (LUT) is partitioned into three 4-bit sub-ROMs based on angular decomposition technique and trigonometric identity. Exploiting the advantages of sine-cosine symmetrical attributes together with XOR logic gates, one sub-ROM block can be removed from the design. These techniques, compressed the ROM into 368 bits. The ROM compressed ratio is 534.2 : 1, with only two adders, two multipliers, and XOR-gates with high frequency resolution of 0.029 Hz. These techniques make the direct digital frequency synthesizer an attractive candidate for wireless communication applications. PMID:24991635

  2. Digitally synthesized high purity, high-voltage radio frequency drive electronics for mass spectrometry

    SciTech Connect

    Schaefer, R. T.; Mojarradi, M.; MacAskill, J. A.; Chutjian, A.; Darrach, M. R.; Madzunkov, S. M.; Shortt, B. J.

    2008-09-15

    Reported herein is development of a quadrupole mass spectrometer controller (MSC) with integrated radio frequency (rf) power supply and mass spectrometer drive electronics. Advances have been made in terms of the physical size and power consumption of the MSC, while simultaneously making improvements in frequency stability, total harmonic distortion, and spectral purity. The rf power supply portion of the MSC is based on a series-resonant LC tank, where the capacitive load is the mass spectrometer itself, and the inductor is a solenoid or toroid, with various core materials. The MSC drive electronics is based on a field programmable gate array (FPGA), with serial peripheral interface for analog-to-digital and digital-to-analog converter support, and RS232/RS422 communications interfaces. The MSC offers spectral quality comparable to, or exceeding, that of conventional rf power supplies used in commercially available mass spectrometers; and as well an inherent flexibility, via the FPGA implementation, for a variety of tasks that includes proportional-integral derivative closed-loop feedback and control of rf, rf amplitude, and mass spectrometer sensitivity. Also provided are dc offsets and resonant dipole excitation for mass selective accumulation in applications involving quadrupole ion traps; rf phase locking and phase shifting for external loading of a quadrupole ion trap; and multichannel scaling of acquired mass spectra. The functionality of the MSC is task specific, and is easily modified by simply loading FPGA registers or reprogramming FPGA firmware.

  3. Digital Frequency Synthesizer For Radar Astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, Ramin; Satorius, Edgar; Robinett, J. Loris, Jr.; Olson, Erlend

    1992-01-01

    Report discusses conceptual digital frequency synthesizer part of programmable local oscillator in radar-astronomy system. Phase must remain continuous during adjustments of frequency, phase noise must be low, and spectral purity must be high. Discusses theory of operation in some mathematical detail and presents new analysis of spectral purity of output.

  4. Possible applications of atomic frequency standards with an internal high resolution digital synthesizer

    NASA Technical Reports Server (NTRS)

    Detoma, E.; Stern, A.

    1993-01-01

    The applications of Atomic Frequency Standards with an internal synthesizer (thereafter referred as 'Synthesized Frequency Standards or Oscillators') with a special emphasis on the Rb oscillator are reviewed. A fractional frequency synthesizer, developed by SEPA, was incorporated in the Frequency Locked Loop of a TFL Rubidium Frequency Standard. This combination allows a frequency settability in steps of 1.5 x 10(exp -12) (optional 1 x 10(exp -13) over a range of 6 x 10(exp -9) without having to resort to change the C-field to tune the output frequency of the device. This capability, coupled to the excellent short term stability of the Rb frequency standard, opens new possibilities for time and frequency users in the various fields (time metrology, navigation, communication, etc.) in which stable frequency standards find their application.

  5. Design of RF source based on Direct Digital Synthesizer

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Qiu, YueHong

    2013-01-01

    A new Radio Frequency (RF) source based on Direct Digital Synthesizer (DDS) is presented in this paper, to improve the performance of the Sound-light tunable filter. A DDS chip called AD9959 is used to produce RF signal. The AD9959 consists of four DDS cores that provide independent frequency, phase, and amplitude control on each channel, and FPGA is used to control AD9959, to ensure a high accurate signal source with multiple signal mode and four channels output is designed. This paper introduces the implementation of system including software and hardware. The test results show that the RF source has 0-200MHz bandwidth and resolution, stability and a series of functions fully realize the scheduled target.

  6. Digitally synthesized phased antenna for multibeam global positioning

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E. (Inventor); Young, Lawrence E. (Inventor)

    2004-01-01

    In a system according to the proposed technique (see figure), the signal received by each element of the array antenna would be subjected to downconversion, and spread-spectrum demodulation and correlation as necessary; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. For the GPS implementation, following downconversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudo random-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be a relatively inexpensive and flexible means for exploiting the inherent multiple-peak/multiple-null aiming capability of a phased-array antenna. In the original intended GPS application, the peaks and nulls could be directed independently for each GPS signal being tracked by the GPS receiver. This will improve the SNR simultaneously for each GPS signal being tracked while steering multiple nulls toward sources of interference. The technique could also be applied to other code-division multiple-access communication systems.

  7. Accuracy of Repetition of Digitized and Synthesized Speech for Young Children in Background Noise

    ERIC Educational Resources Information Center

    Drager, Kathryn D. R.; Clark-Serpentine, Elizabeth A.; Johnson, Kate E.; Roeser, Jennifer L.

    2006-01-01

    Purpose: The present study investigated the intelligibility of digitized and synthesized speech output in background noise for children 3-5 years old. The purpose of the study was to determine whether there was a difference in the intelligibility (ability to repeat) of 3 types of speech output (digitized, DECTalk synthesized, and MacinTalk…

  8. Spur Correlation in an Array of Direct Digital Synthesizers

    DTIC Science & Technology

    2010-11-01

    DDS channel is uncorrelated for 3-bit or higher digital-to-analog converters ( DAC ). This suggests that for an N-channel array of DDSs, a near N...gain in signal-to-quantization noise is possible. This gain will be most apparent for low-bit DACs in which quantization noise is notably higher than...or quantization noise, but does not improve SFDR limited by digital-to-analog converter ( DAC ) quantizer nonlinearities. These measurements can

  9. A ROM-Less Direct Digital Frequency Synthesizer Based on Hybrid Polynomial Approximation

    PubMed Central

    Omran, Qahtan Khalaf; Islam, Mohammad Tariqul; Misran, Norbahiah; Faruque, Mohammad Rashed Iqbal

    2014-01-01

    In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds. PMID:24892092

  10. A ROM-less direct digital frequency synthesizer based on hybrid polynomial approximation.

    PubMed

    Omran, Qahtan Khalaf; Islam, Mohammad Tariqul; Misran, Norbahiah; Faruque, Mohammad Rashed Iqbal

    2014-01-01

    In this paper, a novel design approach for a phase to sinusoid amplitude converter (PSAC) has been investigated. Two segments have been used to approximate the first sine quadrant. A first linear segment is used to fit the region near the zero point, while a second fourth-order parabolic segment is used to approximate the rest of the sine curve. The phase sample, where the polynomial changed, was chosen in such a way as to achieve the maximum spurious free dynamic range (SFDR). The invented direct digital frequency synthesizer (DDFS) has been encoded in VHDL and post simulation was carried out. The synthesized architecture exhibits a promising result of 90 dBc SFDR. The targeted structure is expected to show advantages for perceptible reduction of hardware resources and power consumption as well as high clock speeds.

  11. Synthesizing new, high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Weaver, Claire; Aronson, Meigan

    2015-03-01

    Currently, there is no accepted theory behind type-II, high-temperature superconductors, but there is a distinct relationship between anti-ferromagnetism and superconductivity. Our research focuses on synthesizing new superconducting materials by observing the link between atomic structure and magnetic moments of anti-ferromagnetic compounds and attempting to reproduce the molecular physics of these known materials in new compounds. Consider the square-planar arrangement of the transition metal Fe in the Fe-pnictide superconductors of the ZrCuSiAs ``11 11'' and the ThCr2Si2 ``122'' structure types. We believe that the physics behind this superconductor, where Fe has d6 valence electrons, contributes to the superconducting state, not the presence of Fe itself. For this reason, we are synthesizing materials containing neighboring transition metals, like Mn and Co, combined with other elements in similar crystal lattice arrangements, having ionization properties that hopefully impose d6 valence electrons on the transition metals. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  12. Reconfigurable firmware-defined radios synthesized from standard digital logic cells

    NASA Astrophysics Data System (ADS)

    Faisal, Muhammad; Park, Youngmin; Wentzloff, David D.

    2011-06-01

    This paper presents recent work on reconfigurable all-digital radio architectures. We leverage the flexibility and scalability of synthesized digital cells to construct reconfigurable radio architectures that consume significantly less power than a software defined radio implementing similar architectures. We present two prototypes of such architectures that can receive and demodulate FM and FRS band signals. Moreover, a radio architecture based on a reconfigurable alldigital phase-locked loop for coherent demodulation is presented.

  13. Low-latency digital frequency synthesizer using the residue number system

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.

    1993-01-01

    A low-latency frequency synthesizer using the Direct Digital Synthesis (DDS) technique has been designed. Called the Residue Assisted Frequency Synthesizer (RAFS), it exhibits frequency switching times which are reduced by more than 50 percent below previously published designs. The switching speed advantage is made possible by the use of the Residue Number System, which allows the pipeline lengths in the Phase Accumulator and other circuitry to be reduced significantly.

  14. High Rate Digital Demodulator ASIC

    NASA Technical Reports Server (NTRS)

    Ghuman, Parminder; Sheikh, Salman; Koubek, Steve; Hoy, Scott; Gray, Andrew

    1998-01-01

    The architecture of High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation in other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA's Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an over-view of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

  15. Multilayer graphane synthesized under high hydrogen pressure

    DOE PAGES

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; ...

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis inmore » the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.« less

  16. Multilayer graphane synthesized under high hydrogen pressure

    SciTech Connect

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; Bulychev, B. M.; Fedotov, V. K.; Fursova, T. N.; Kolesnikov, A. I.; Kulakov, V. I.; Lukashev, R. V.; Matveev, D. V.; Sakharov, M. K.; Shulga, Y. M.

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis in the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.

  17. Synthesized femtosecond laser pulse source for two-wavelength contouring with simultaneously recorded digital holograms.

    PubMed

    Hansel, Thomas; Steinmeyer, Günter; Grunwald, Ruediger; Falldorf, Claas; Bonitz, Jens; Kaufmann, Christian; Kebbel, Volker; Griebner, Uwe

    2009-02-16

    A dual-wavelength femtosecond laser pulse source and its application for digital holographic single-shot contouring are presented. The synthesized laser source combines sub-picosecond time scales with a wide reconstruction range. A center wavelength distance of the two separated pulses of only 15 nm with a high contrast was demonstrated by spectral shaping of the 50 nm broad seed spectrum centered at 800 nm. Owing to the resulting synthetic wavelength, the scan depth range without phase ambiguity is extended to the 100-microm-range. Single-shot dual-wavelength imaging is achieved by using two CMOS cameras in a Twyman-Green interferometer, which is extended by a polarization encoding sequence to separate the holograms. The principle of the method is revealed, and experimental results concerning a single axis scanner mirror operating at a resonance frequency of 0.5 kHz are presented. Within the synthetic wavelength, the phase difference information of the object was unambiguously retrieved and the 3D-shape calculated. To the best of our knowledge, this is the first time that single-shot two-wavelength contouring on a sub-ps time scale is reported.

  18. Method For Synthesizing Extremely High-Temperature Melting Materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  19. Method for synthesizing extremely high-temperature melting materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2007-11-06

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as carbides and transition-metal, lanthanide and actinide oxides, using an aerodynamic levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  20. Method for Synthesizing Extremeley High Temperature Melting Materials

    DOEpatents

    Saboungi, Marie-Louise and Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  1. High Performance Proactive Digital Forensics

    NASA Astrophysics Data System (ADS)

    Alharbi, Soltan; Moa, Belaid; Weber-Jahnke, Jens; Traore, Issa

    2012-10-01

    With the increase in the number of digital crimes and in their sophistication, High Performance Computing (HPC) is becoming a must in Digital Forensics (DF). According to the FBI annual report, the size of data processed during the 2010 fiscal year reached 3,086 TB (compared to 2,334 TB in 2009) and the number of agencies that requested Regional Computer Forensics Laboratory assistance increasing from 689 in 2009 to 722 in 2010. Since most investigation tools are both I/O and CPU bound, the next-generation DF tools are required to be distributed and offer HPC capabilities. The need for HPC is even more evident in investigating crimes on clouds or when proactive DF analysis and on-site investigation, requiring semi-real time processing, are performed. Although overcoming the performance challenge is a major goal in DF, as far as we know, there is almost no research on HPC-DF except for few papers. As such, in this work, we extend our work on the need of a proactive system and present a high performance automated proactive digital forensic system. The most expensive phase of the system, namely proactive analysis and detection, uses a parallel extension of the iterative z algorithm. It also implements new parallel information-based outlier detection algorithms to proactively and forensically handle suspicious activities. To analyse a large number of targets and events and continuously do so (to capture the dynamics of the system), we rely on a multi-resolution approach to explore the digital forensic space. Data set from the Honeynet Forensic Challenge in 2001 is used to evaluate the system from DF and HPC perspectives.

  2. High speed holographic digital recorder.

    PubMed

    Roberts, H N; Watkins, J W; Johnson, R H

    1974-04-01

    Concepts, feasibility experiments, and key component developments are described for a holographic digital record/reproduce system with the potential for 1.0 Gbit/sec rates and higher. Record rates of 500 Mbits/sec have been demonstrated with a ten-channel acoustooptic modulator array and a mode-locked, cavity-dumped argon-ion laser. Acoustooptic device technology has been advanced notably during the development of mode lockers, cavity dumpers, beam deflectors, and multichannel modulator arrays. The development of high speed multichannel photodetector arrays for the readout subsystem requires special attention. The feasibility of 1.0 Gbits/sec record rates has been demonstrated.

  3. High speed quantitative digital microscopy

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; Price, K. H.; Eskenazi, R.; Ovadya, M. M.; Navon, M. A.

    1984-01-01

    Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

  4. High-density digital recording

    NASA Technical Reports Server (NTRS)

    Kalil, F. (Editor); Buschman, A. (Editor)

    1985-01-01

    The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

  5. Note: Directly measuring the direct digital synthesizer frequency chirp-rate for an atom interferometer.

    PubMed

    Tao, Juan-Juan; Zhou, Min-Kang; Zhang, Qiao-Zhen; Cui, Jia-Feng; Duan, Xiao-Chun; Shao, Cheng-Gang; Hu, Zhong-Kun

    2015-09-01

    During gravity measurements with Raman type atom interferometry, the frequency of the laser used to drive Raman transition is scanned by chirping the frequency of a direct digital synthesizer (DDS), and the local gravity is determined by precisely measuring the chip rate α of DDS. We present an effective method that can directly evaluate the frequency chirp rate stability of our DDS. By mixing a pair of synchronous linear sweeping signals, the chirp rate fluctuation is precisely measured with a frequency counter. The measurement result shows that the relative α instability can reach 5.7 × 10(-11) in 1 s, which is neglectable in a 10(-9) g level atom interferometry gravimeter.

  6. Note: Directly measuring the direct digital synthesizer frequency chirp-rate for an atom interferometer

    SciTech Connect

    Tao, Juan-Juan; Zhou, Min-Kang E-mail: zmk@hust.edu.cn; Zhang, Qiao-Zhen; Cui, Jia-Feng; Duan, Xiao-Chun; Shao, Cheng-Gang; Hu, Zhong-Kun E-mail: zmk@hust.edu.cn

    2015-09-15

    During gravity measurements with Raman type atom interferometry, the frequency of the laser used to drive Raman transition is scanned by chirping the frequency of a direct digital synthesizer (DDS), and the local gravity is determined by precisely measuring the chip rate α of DDS. We present an effective method that can directly evaluate the frequency chirp rate stability of our DDS. By mixing a pair of synchronous linear sweeping signals, the chirp rate fluctuation is precisely measured with a frequency counter. The measurement result shows that the relative α instability can reach 5.7 × 10{sup −11} in 1 s, which is neglectable in a 10{sup −9} g level atom interferometry gravimeter.

  7. Spacelab high density digital recorders

    NASA Technical Reports Server (NTRS)

    Blais, R. A.

    1983-01-01

    The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.

  8. Optimization and Implementation of Scaling-Free CORDIC-Based Direct Digital Frequency Synthesizer for Body Care Area Network Systems

    PubMed Central

    Juang, Ying-Shen; Ko, Lu-Ting; Chen, Jwu-E.; Sung, Tze-Yun; Hsin, Hsi-Chin

    2012-01-01

    Coordinate rotation digital computer (CORDIC) is an efficient algorithm for computations of trigonometric functions. Scaling-free-CORDIC is one of the famous CORDIC implementations with advantages of speed and area. In this paper, a novel direct digital frequency synthesizer (DDFS) based on scaling-free CORDIC is presented. The proposed multiplier-less architecture with small ROM and pipeline data path has advantages of high data rate, high precision, high performance, and less hardware cost. The design procedure with performance and hardware analysis for optimization has also been given. It is verified by Matlab simulations and then implemented with field programmable gate array (FPGA) by Verilog. The spurious-free dynamic range (SFDR) is over 86.85 dBc, and the signal-to-noise ratio (SNR) is more than 81.12 dB. The scaling-free CORDIC-based architecture is suitable for VLSI implementations for the DDFS applications in terms of hardware cost, power consumption, SNR, and SFDR. The proposed DDFS is very suitable for medical instruments and body care area network systems. PMID:23251230

  9. Optimization and implementation of scaling-free CORDIC-based direct digital frequency synthesizer for body care area network systems.

    PubMed

    Juang, Ying-Shen; Ko, Lu-Ting; Chen, Jwu-E; Sung, Tze-Yun; Hsin, Hsi-Chin

    2012-01-01

    Coordinate rotation digital computer (CORDIC) is an efficient algorithm for computations of trigonometric functions. Scaling-free-CORDIC is one of the famous CORDIC implementations with advantages of speed and area. In this paper, a novel direct digital frequency synthesizer (DDFS) based on scaling-free CORDIC is presented. The proposed multiplier-less architecture with small ROM and pipeline data path has advantages of high data rate, high precision, high performance, and less hardware cost. The design procedure with performance and hardware analysis for optimization has also been given. It is verified by Matlab simulations and then implemented with field programmable gate array (FPGA) by Verilog. The spurious-free dynamic range (SFDR) is over 86.85 dBc, and the signal-to-noise ratio (SNR) is more than 81.12 dB. The scaling-free CORDIC-based architecture is suitable for VLSI implementations for the DDFS applications in terms of hardware cost, power consumption, SNR, and SFDR. The proposed DDFS is very suitable for medical instruments and body care area network systems.

  10. Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI Instruments at Low-Field

    PubMed Central

    Asfour, Aktham; Raoof, Kosai; Yonnet, Jean-Paul

    2013-01-01

    A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer). The SDR includes a direct analog-to-digital conversion and a Digital Down Conversion (digital quadrature demodulation, decimation filtering, processing gain…). The various aspects of the concept and of the realization are addressed with some details. These include both hardware design and software considerations. One of the underlying ideas is to enable such NMR systems to “enjoy” from existing advanced technology that have been realized in other research areas, especially in telecommunication domain. Another goal is to make these systems easy to build and replicate so as to help research groups in realizing dedicated NMR desktops for a large palette of new applications. We also would like to give readers an idea of the current trends in this field. The performances of the developed electronics are discussed throughout the paper. First FID (Free Induction Decay) signals are also presented. Some development perspectives of our work in the area of low-field NMR/MRI will be finally addressed. PMID:24287540

  11. Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI instruments at low-field.

    PubMed

    Asfour, Aktham; Raoof, Kosai; Yonnet, Jean-Paul

    2013-11-27

    A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer). The SDR includes a direct analog-to-digital conversion and a Digital Down Conversion (digital quadrature demodulation, decimation filtering, processing gain…). The various aspects of the concept and of the realization are addressed with some details. These include both hardware design and software considerations. One of the underlying ideas is to enable such NMR systems to "enjoy" from existing advanced technology that have been realized in other research areas, especially in telecommunication domain. Another goal is to make these systems easy to build and replicate so as to help research groups in realizing dedicated NMR desktops for a large palette of new applications. We also would like to give readers an idea of the current trends in this field. The performances of the developed electronics are discussed throughout the paper. First FID (Free Induction Decay) signals are also presented. Some development perspectives of our work in the area of low-field NMR/MRI will be finally addressed.

  12. High-speed digital plotter

    NASA Technical Reports Server (NTRS)

    Gray, J., Jr.

    1971-01-01

    Modified typewriter mechanism with standard logic components provides digital plot of output of multichannel analyzer. Unit plots irregular curves at approximately 14 channels per second, and smooth curves at over 25 channels per second, and is not subject to analog error or drift.

  13. High-Speed Digital Interferometry

    NASA Technical Reports Server (NTRS)

    De Vine, Glenn; Shaddock, Daniel A.; Ware, Brent; Spero, Robert E.; Wuchenich, Danielle M.; Klipstein, William M.; McKenzie, Kirk

    2012-01-01

    Digitally enhanced heterodyne interferometry (DI) is a laser metrology technique employing pseudo-random noise (PRN) codes phase-modulated onto an optical carrier. Combined with heterodyne interferometry, the PRN code is used to select individual signals, returning the inherent interferometric sensitivity determined by the optical wavelength. The signal isolation arises from the autocorrelation properties of the PRN code, enabling both rejection of spurious signals (e.g., from scattered light) and multiplexing capability using a single metrology system. The minimum separation of optical components is determined by the wavelength of the PRN code.

  14. High-yielding syntheses of hydrophilic, conjugatable chlorins and bacteriochlorins†

    PubMed Central

    McCarthy, Jason R.; Bhaumik, Jayeeta; Merbouh, Nabyl; Weissleder, Ralph

    2009-01-01

    SUMMARY Next-generation photodynamic therapy agents based upon the conjugation of multiple photosensitizers to a targeting backbone will allow for more efficacious light-based therapies. To this end, we have developed glucose-modified chlorins and bacteriochlorins featuring a reactive carboxylic acid linker for conjugation to targeting moities. The photosensitizers were synthesized in relatively high yields from meso-tetra(p-aminophenyl)porphyrin, and resulted in neutral, hydrophilic chromophores with superb absorption profiles in the far-red and near-infrared portions of the electromagnetic spectrum. In addition, conjugation of these photosensitizers to a model nanoscaffold (crosslinked dextran-coated nanoparticles) demonstrated that the inclusion of hydrophilic sugar moieties increased the number of dyes that can be loaded while maintaining suspension stability. The described compounds are expected to be particularly useful in the synthesis of a number of targeted nanotherapeutic systems. PMID:19675897

  15. Highly scalable digital front end architectures for digital printing

    NASA Astrophysics Data System (ADS)

    Staas, David

    2011-01-01

    HP's digital printing presses consume a tremendous amount of data. The architectures of the Digital Front Ends (DFEs) that feed these large, very fast presses have evolved from basic, single-RIP (Raster Image Processor) systems to multirack, distributed systems that can take a PDF file and deliver data in excess of 3 Gigapixels per second to keep the presses printing at 2000+ pages per minute. This paper highlights some of the more interesting parallelism features of our DFE architectures. The high-performance architecture developed over the last 5+ years can scale up to HP's largest digital press, out to multiple mid-range presses, and down into a very low-cost single box deployment for low-end devices as appropriate. Principles of parallelism pervade every aspect of the architecture, from the lowest-level elements of jobs to parallel imaging pipelines that feed multiple presses. From cores to threads to arrays to network teams to distributed machines, we use a systematic approach to move bottlenecks. The ultimate goals of these efforts are: to take the best advantage of the prevailing hardware options at our disposal; to reduce power consumption and cooling requirements; and to ultimately reduce the cost of the solution to our customers.

  16. Towards practical, high-capacity, low-maintenance information storage in synthesized DNA.

    PubMed

    Goldman, Nick; Bertone, Paul; Chen, Siyuan; Dessimoz, Christophe; LeProust, Emily M; Sipos, Botond; Birney, Ewan

    2013-02-07

    Digital production, transmission and storage have revolutionized how we access and use information but have also made archiving an increasingly complex task that requires active, continuing maintenance of digital media. This challenge has focused some interest on DNA as an attractive target for information storage because of its capacity for high-density information encoding, longevity under easily achieved conditions and proven track record as an information bearer. Previous DNA-based information storage approaches have encoded only trivial amounts of information or were not amenable to scaling-up, and used no robust error-correction and lacked examination of their cost-efficiency for large-scale information archival. Here we describe a scalable method that can reliably store more information than has been handled before. We encoded computer files totalling 739 kilobytes of hard-disk storage and with an estimated Shannon information of 5.2 × 10(6) bits into a DNA code, synthesized this DNA, sequenced it and reconstructed the original files with 100% accuracy. Theoretical analysis indicates that our DNA-based storage scheme could be scaled far beyond current global information volumes and offers a realistic technology for large-scale, long-term and infrequently accessed digital archiving. In fact, current trends in technological advances are reducing DNA synthesis costs at a pace that should make our scheme cost-effective for sub-50-year archiving within a decade.

  17. High Speed Digital Camera Technology Review

    NASA Technical Reports Server (NTRS)

    Clements, Sandra D.

    2009-01-01

    A High Speed Digital Camera Technology Review (HSD Review) is being conducted to evaluate the state-of-the-shelf in this rapidly progressing industry. Five HSD cameras supplied by four camera manufacturers participated in a Field Test during the Space Shuttle Discovery STS-128 launch. Each camera was also subjected to Bench Tests in the ASRC Imaging Development Laboratory. Evaluation of the data from the Field and Bench Tests is underway. Representatives from the imaging communities at NASA / KSC and the Optical Systems Group are participating as reviewers. A High Speed Digital Video Camera Draft Specification was updated to address Shuttle engineering imagery requirements based on findings from this HSD Review. This draft specification will serve as the template for a High Speed Digital Video Camera Specification to be developed for the wider OSG imaging community under OSG Task OS-33.

  18. High temperature superconducting digital circuits and subsystems

    SciTech Connect

    Martens, J.S.; Pance, A.; Whiteley, S.R.; Char, K.; Johansson, M.F.; Lee, L.; Hietala, V.M.; Wendt, J.R.; Hou, S.Y.; Phillips, J.

    1993-10-01

    The advances in the fabrication of high temperature superconducting devices have enabled the demonstration of high performance and useful digital circuits and subsystems. The yield and uniformity of the devices is sufficient for circuit fabrication at the medium scale integration (MSI) level with performance not seen before at 77 K. The circuits demonstrated to date include simple gates, counters, analog to digital converters, and shift registers. All of these are mid-sized building blocks for potential applications in commercial and military systems. The processes used for these circuits and blocks will be discussed along with observed performance data.

  19. High resolution digital holography based on the point source scanning

    NASA Astrophysics Data System (ADS)

    Wang, Minchao; Wang, Dayong; Rong, Lu; Wang, Yunxin; Wang, Fengpeng; Lin, Qiaowen

    2016-10-01

    Digital holographic microscopy has been widely used for the imaging of micro-objects and biological samples. Lensless in-line digital holographic microscopy is capable of wide field-of-view imaging. However the spatial resolution of the reconstructed images is limited by the pixel size of the detector. The relative position shift between the sample and the detector can effectively improve the resolution in the traditional sub-pixel shifting method, but it requires a high precision of translation stage. To overcome this problem, we propose a method based on the point source scanning to realize sub-pixel shifting. High precision sub-pixel shifting is achieved easily by using the geometric between point source and detector. Through moving the point source, multiple holograms with sub-pixel shifts are captured. These holograms are merged together to obtained a high resolution hologram by a synthesizing algorithm. Then, the high resolution reconstructed image of the object can be obtained by the angular spectrum algorithm. The feasibility of the proposed method is demonstrated by simulation and experiments. A USAF resolution test target was used as the object. Compared with the traditional digital holography, a higher resolution reconstructed image is obtained by our method. The proposed method has the advantages of simple recording setup and lower precision requirement of the translation stage. It can achieve the wide field-of-view and high resolution imaging.

  20. Implementation of Synthesized Two-dimensional Mammography in a Population-based Digital Breast Tomosynthesis Screening Program.

    PubMed

    Zuckerman, Samantha P; Conant, Emily F; Keller, Brad M; Maidment, Andrew D A; Barufaldi, Bruno; Weinstein, Susan P; Synnestvedt, Marie; McDonald, Elizabeth S

    2016-12-01

    Purpose To evaluate the early implementation of synthesized two-dimensional (s2D) mammography in a population screened entirely with s2D and digital breast tomosynthesis (DBT) (referred to as s2D/DBT) and compare recall rates and cancer detection rates to historic outcomes of digital mammography combined with DBT (referred to as digital mammography/DBT) screening. Materials and Methods This was an institutional review board-approved and HIPAA-compliant retrospective interpretation of prospectively acquired data with waiver of informed consent. Compared were recall rates, biopsy rates, cancer detection rates, and radiation dose for 15 571 women screened with digital mammography/DBT from October 1, 2011, to February 28, 2013, and 5366 women screened with s2D/DBT from January 7, 2015, to June 30, 2015. Two-sample z tests of equal proportions were used to determine statistical significance. Results Recall rate for s2D/DBT versus digital mammography/DBT was 7.1% versus 8.8%, respectively (P < .001). Biopsy rate for s2D/DBT versus digital mammography/DBT decreased (1.3% vs 2.0%, respectively; P = .001). There was no significant difference in cancer detection rate for s2D/DBT versus digital mammography/DBT (5.03 of 1000 vs 5.45 of 1000, respectively; P = .72). The average glandular dose was 39% lower in s2D/DBT versus digital mammography/DBT (4.88 mGy vs 7.97 mGy, respectively; P < .001). Conclusion Screening with s2D/DBT in a large urban practice resulted in similar outcomes compared with digital mammography/DBT imaging. Screening with s2D/DBT allowed for the benefits of DBT with a decrease in radiation dose compared with digital mammography/DBT. (©) RSNA, 2016 An earlier incorrect version of this article appeared online. This article was corrected on August 11, 2016.

  1. Very high-speed digital holography

    NASA Astrophysics Data System (ADS)

    Pérez López, Carlos; Mendoza Santoyo, Fernando; Rodríguez Vera, Ramón; Moreno, David; Barrientos, Bernardino

    2006-08-01

    It is reported for the first time the use of a high speed camera in digital holography with an out of plane sensitivity. The camera takes the image plane holograms of a cw laser illuminated rectangular framed polyester material at a rate of 5000 per second, that is a spacing of 200 microseconds between holograms, and 512 by 500 pixels at 10 bit resolution. The freely standing object has a random movement due to non controlled environmental air currents. As is usual with this technique each digital hologram is Fourier processed in order to obtain upon comparison with a consecutive digital hologram the phase map of the displacement. High quality results showing the amplitude and direction of the random movement are presented.

  2. High resolution digital delay timer

    DOEpatents

    Martin, Albert D.

    1988-01-01

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

  3. Digital control of highly augmented combat rotorcraft

    NASA Technical Reports Server (NTRS)

    Tischler, Mark B.

    1987-01-01

    Proposed concepts for the next generation of combat helicopters are to be embodied in a complex, highly maneuverable, multiroled vehicle with avionics systems. Single pilot and nap-of-the-Earth operations require handling qualities which minimize the involvement of the pilot in basic stabilization tasks. To meet these requirements will demand a full authority, high-gain, multimode, multiply-redundant, digital flight-control system. The gap between these requirements and current low-authority, low-bandwidth operational rotorcraft flight-control technology is considerable. This research aims at smoothing the transition between current technology and advanced concept requirements. The state of the art of high-bandwidth digital flight-control systems are reviewed; areas of specific concern for flight-control systems of modern combat are exposed; and the important concepts are illustrated in design and analysis of high-gain, digital systems with a detailed case study involving a current rotorcraft system. Approximate and exact methods are explained and illustrated for treating the important concerns which are unique to digital systems.

  4. Reviews and syntheses: Australian vegetation phenology: new insights from satellite remote sensing and digital repeat photography

    NASA Astrophysics Data System (ADS)

    Moore, Caitlin E.; Brown, Tim; Keenan, Trevor F.; Duursma, Remko A.; van Dijk, Albert I. J. M.; Beringer, Jason; Culvenor, Darius; Evans, Bradley; Huete, Alfredo; Hutley, Lindsay B.; Maier, Stefan; Restrepo-Coupe, Natalia; Sonnentag, Oliver; Specht, Alison; Taylor, Jeffrey R.; van Gorsel, Eva; Liddell, Michael J.

    2016-09-01

    Phenology is the study of periodic biological occurrences and can provide important insights into the influence of climatic variability and change on ecosystems. Understanding Australia's vegetation phenology is a challenge due to its diverse range of ecosystems, from savannas and tropical rainforests to temperate eucalypt woodlands, semi-arid scrublands, and alpine grasslands. These ecosystems exhibit marked differences in seasonal patterns of canopy development and plant life-cycle events, much of which deviates from the predictable seasonal phenological pulse of temperate deciduous and boreal biomes. Many Australian ecosystems are subject to irregular events (i.e. drought, flooding, cyclones, and fire) that can alter ecosystem composition, structure, and functioning just as much as seasonal change. We show how satellite remote sensing and ground-based digital repeat photography (i.e. phenocams) can be used to improve understanding of phenology in Australian ecosystems. First, we examine temporal variation in phenology on the continental scale using the enhanced vegetation index (EVI), calculated from MODerate resolution Imaging Spectroradiometer (MODIS) data. Spatial gradients are revealed, ranging from regions with pronounced seasonality in canopy development (i.e. tropical savannas) to regions where seasonal variation is minimal (i.e. tropical rainforests) or high but irregular (i.e. arid ecosystems). Next, we use time series colour information extracted from phenocam imagery to illustrate a range of phenological signals in four contrasting Australian ecosystems. These include greening and senescing events in tropical savannas and temperate eucalypt understorey, as well as strong seasonal dynamics of individual trees in a seemingly static evergreen rainforest. We also demonstrate how phenology links with ecosystem gross primary productivity (from eddy covariance) and discuss why these processes are linked in some ecosystems but not others. We conclude that

  5. High-speed Digital Color Imaging Pyrometry

    DTIC Science & Technology

    2011-08-01

    and environment of the events. To overcome these challenges, we have characterized and calibrated a digital high-speed color camera that may be...correction) to determine their effect on the calculated temperature. Using this technique with a Phantom color camera , we measured the temperature of...constant value of approximately 1980~K. 15. SUBJECT TERMS Pyrometry, color camera 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT

  6. Highly linear, sensitive analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Cox, J.; Finley, W. R.

    1969-01-01

    Analog-to-digital converter converts 10 volt full scale input signal into 13 bit digital output. Advantages include high sensitivity, linearity, low quantitizing error, high resistance to mechanical shock and vibration loads, and temporary data storage capabilities.

  7. Very high speed cw digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Pérez-López, Carlos; de La Torre-Ibarra, Manuel H.; Mendoza Santoyo, Fernando

    2006-10-01

    It is reported for the first time the use of a very high speed camera in digital holographic interferometry with an out of plane sensitivity setup. The image plane holograms of a spherical latex balloon illuminated by a cw laser were acquired at a rate of 4000 frames per second, representing a time spacing between holograms of 250 microseconds, for 512 × 512 pixels at 8 bits resolution. Two types of tests were accomplished for a proof of principle of the technique, one with no constrains on the object which meant random movements due to non controlled environmental air currents, and the other with specific controlled conditions on the object. Results presented correspond to a random sample of sequential digital holograms, chosen from a 1 second exposure, individually Fourier processed in order to perform the usual comparison by subtraction between consecutive pairs thus obtaining the phase map of the object out of plane displacement, shown as a movie.

  8. A new hexagonal carbon nitride synthesized at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Sougawa, Masaya; Shima, Yuta; Hirai, Masaaki; Takarabe, Kenichi; Okada, Taku; InstituteSolid State Physics, University of Tokyo Collaboration

    2013-06-01

    A new hexagonal carbon nitride has been synthesized by subjecting the C3N4Hxprecursor to high pressure and high temperature. The XRD pattern of the new hexagonal carbon nitride is indexed as the hexagonal unit cell with the lattice parameters; a = b = 2.83 Å, c = 9.82 Å (V = 68.10 Å3) . The unit cell of this new hexagonal carbon nitride differs from the several hexagonal carbon nitrides reported so far by the theoretical and experimental studies. Hart et al. proposed the hexagonal CN structure with 1:1 stoichiometry is based on the known GaSe layer with the unit cell parameters of the hexagonal unit a = b = 2.37 Å, c = 11.38 Å (V = 55.36 Å3) , respectively, and the space group is P63/mmc. Bojdys et al. synthesized the graphitic-C3N4 (g-C3N4) with the hexagonal unit cell with the lattice parameters; a = b = 8.43 Å, c = 6.72 Å (V = 414.09 Å3) , and the space group is P63cm. These reported hexagonal lattice constants disagree with the new hexagonal carbon nitrides synthesized in this report. We will report the full analysis of the crystal structure of the new hexagonal carbon nitride at the conference.

  9. A novel method to synthesize high purity, nanostructured copper

    SciTech Connect

    Hodge, A M; Wang, Y M; Barbee, T W

    2005-08-30

    Nanostructured high purity (99.999%) copper foils, 10 cm in diameter and 22-25 microns thick were produced using nanoscale multilayer technology. The foils were produced using five different layer thicknesses ranging from 1.25 to 43.6 nm (18,000 to 520 layers). This process delivers the ability to produce multiple large-scale samples during a single deposition run with very small residual stresses. Tensile and indentation tests demonstrate that the material produced is a high strength copper ({sigma}{sub y} {approx} 540-690 MPa).

  10. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    NASA Astrophysics Data System (ADS)

    He, Yubin; Pan, Jiefeng; Wu, Liang; Zhu, Yuan; Ge, Xiaolin; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2015-08-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH- conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH- conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology.

  11. A Novel Process to Synthesize High-Quality Ferrovanadium Nitride

    NASA Astrophysics Data System (ADS)

    Wu, Yue-Dong; Zhang, Guo-Hua; Chou, Kuo-Chih

    2016-12-01

    In the present work, high-quality ferrovanadium nitride, which has a relative high nitrogen content and a low carbon content, has been prepared by roasting the mixture of vanadium pentoxide, carbon, and ferric oxide under N2 atmosphere in the temperature range from 1673 K to 1873 K (1400 °C to 1600 °C). The effects of carbon addition, reaction temperature, and heat treatment process were discussed. It was found that the carbon addition had a great effect on the nitrogen content and residual carbon, and the optimum carbon content was established to obtain the maximum nitrogen content and low carbon content. The reaction temperature in the range from 1673 K to 1873 K (1400 °C to 1600 °C) has a smaller effect on the final nitrogen content, and it also affects the degree of agglomeration of particles, which were observed by scanning electron microscope. From the results of thermodynamic calculation, energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD), it was deduced that the reaction sequence of V2O5 with N2 from 1673 K to 1873 K (1400 °C to 1600 °C) was V2O5 → VO2 → V2O3 → V(N, C, O) → V(N, C). There is a little solid solubility of carbon in the final product VN.

  12. Synthesizing High-Quality Graphene Membranes for Engineering Diffusion Barriers

    NASA Astrophysics Data System (ADS)

    Singha Roy, Susmit

    We demonstrate significant advances in the fundamental understanding and engineering of scalable graphene diffusion barriers. Experimental studies have established that defect-free non-scalable graphene is an excellent barrier material, however its scalable counterparts are still well behind in terms of performance. The latter's ability to perform as a barrier membrane is compromised primarily by the presence of three major problems - high density of defects, self-degradation in ambient environment and induced electrochemical oxidation of the underlying material. First, we develop an in-depth understanding of how diffusion occurs through monolayer graphene grown via chemical vapor deposition. It is shown that the atomic membrane is impenetrable in the pristine regions, however it is easily penetrated by oxygen and water at grain boundaries and intrinsic pinholes. Second, we study in detail the self-deterioration of graphene in ambient and quantify the evolution, kinetics, and energetics of the degradation process both in the pristine and intrinsically defective regions of graphene. It is also found that the degradation process is accelerated in the presence of water vapor. Third, we find that the overall defect density of a graphene membrane is primarily determined by the density of its intrinsic pinholes and grain boundaries. We demonstrate that the density on intrinsic pinholes can be significantly reduced by reducing the surface roughness of the growth substrate which is achieved by regulating the pre-growth annealing time and temperature. The density of the grain boundaries can be altered by varying the internucleation distance during the growth of the membrane. Fourth, when graphene is used as a corrosion barrier for metals, we establish that the electrochemical corrosion of the metal can be drastically reduced by adding an ultra-thin electrically insulating layer between the graphene and the metal. In addition, the barrier performance is enhanced greatly by

  13. Boron-doped diamond synthesized at high-pressure and high-temperature with metal catalyst

    NASA Astrophysics Data System (ADS)

    Shakhov, Fedor M.; Abyzov, Andrey M.; Kidalov, Sergey V.; Krasilin, Andrei A.; Lähderanta, Erkki; Lebedev, Vasiliy T.; Shamshur, Dmitriy V.; Takai, Kazuyuki

    2017-04-01

    The boron-doped diamond (BDD) powder consisting of 40-100 μm particles was synthesized at 5 GPa and 1500-1600 °C from a mixture of 50 wt% graphite and 50 wt% Ni-Mn catalyst with an addition of 1 wt% or 5 wt% boron powder. The size of crystal domains of doped and non-doped diamond was evaluated as a coherent scattering region by X-ray diffraction (XRD) and using small-angle neutron scattering (SANS), being ≥180 nm (XRD) and 100 nm (SANS). Magnetic impurities of NiMnx originating from the catalyst in the synthesis, which prevent superconductivity, were detected by magnetization measurements at 2-300 K. X-ray photoelectron spectroscopy, the temperature dependence of the resistivity, XRD, and Raman spectroscopy reveal that the concentration of electrically active boron is as high as (2±1)×1020 cm-3 (0.1 at%). To the best of our knowledge, this is the highest boron content for BDD synthesized in high-pressure high-temperature process with metal catalysts.

  14. High frame-rate digital radiographic videography

    SciTech Connect

    King, N.S.P.; Cverna, F.H.; Albright, K.L.; Jaramillo, S.A.; Yates, G.J.; McDonald, T.E.; Flynn, M.J.; Tashman, S.

    1994-09-01

    High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100-microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

  15. High-performance digital color video camera

    NASA Astrophysics Data System (ADS)

    Parulski, Kenneth A.; D'Luna, Lionel J.; Benamati, Brian L.; Shelley, Paul R.

    1992-01-01

    Typical one-chip color cameras use analog video processing circuits. An improved digital camera architecture has been developed using a dual-slope A/D conversion technique and two full-custom CMOS digital video processing integrated circuits, the color filter array (CFA) processor and the RGB postprocessor. The system used a 768 X 484 active element interline transfer CCD with a new field-staggered 3G color filter pattern and a lenslet overlay, which doubles the sensitivity of the camera. The industrial-quality digital camera design offers improved image quality, reliability, manufacturability, while meeting aggressive size, power, and cost constraints. The CFA processor digital VLSI chip includes color filter interpolation processing, an optical black clamp, defect correction, white balance, and gain control. The RGB postprocessor digital integrated circuit includes a color correction matrix, gamma correction, 2D edge enhancement, and circuits to control the black balance, lens aperture, and focus.

  16. High-performance digital color video camera

    NASA Astrophysics Data System (ADS)

    Parulski, Kenneth A.; Benamati, Brian L.; D'Luna, Lionel J.; Shelley, Paul R.

    1991-06-01

    Typical one-chip color cameras use analog video processing circuits. An improved digital camera architecture has been developed using a dual-slope A/D conversion technique, and two full custom CMOS digital video processing ICs, the 'CFA processor' and the 'RGB post- processor.' The system uses a 768 X 484 active element interline transfer CCD with a new 'field-staggered 3G' color filter pattern and a 'lenslet' overlay, which doubles the sensitivity of the camera. The digital camera design offers improved image quality, reliability, and manufacturability, while meeting aggressive size, power, and cost constraints. The CFA processor digital VLSI chip includes color filter interpolation processing, an optical black clamp, defect correction, white balance, and gain control. The RGB post-processor digital IC includes a color correction matrix, gamma correction, two-dimensional edge-enhancement, and circuits to control the black balance, lens aperture, and focus.

  17. High-Rate Digital Receiver Board

    NASA Technical Reports Server (NTRS)

    Ghuman, Parminder; Bialas, Thomas; Brambora, Clifford; Fisher, David

    2004-01-01

    A high-rate digital receiver (HRDR) implemented as a peripheral component interface (PCI) board has been developed as a prototype of compact, general-purpose, inexpensive, potentially mass-producible data-acquisition interfaces between telemetry systems and personal computers. The installation of this board in a personal computer together with an analog preprocessor enables the computer to function as a versatile, highrate telemetry-data-acquisition and demodulator system. The prototype HRDR PCI board can handle data at rates as high as 600 megabits per second, in a variety of telemetry formats, transmitted by diverse phase-modulation schemes that include binary phase-shift keying and various forms of quadrature phaseshift keying. Costing less than $25,000 (as of year 2003), the prototype HRDR PCI board supplants multiple racks of older equipment that, when new, cost over $500,000. Just as the development of standard network-interface chips has contributed to the proliferation of networked computers, it is anticipated that the development of standard chips based on the HRDR could contribute to reductions in size and cost and increases in performance of telemetry systems.

  18. B-C-N compound synthesized under high temperature and high pressure

    NASA Astrophysics Data System (ADS)

    Tian, Y. J.; He, J. L.; Yu, D. L.; Li, D. C.; Zou, G. T.; Jia, X. R.; Chen, L. X.; Yanagisawa, O.

    2002-01-01

    Crystalline hexagonal B(N1-xCx) and cubic B-C-N compounds have been synthesized from a precursor produced from melamine and boric acid by application of high temperature and high pressure. The synthesized products were characterized by X-ray diffraction. The lattice parameters for the hexagonal crystal are a = 2.506 Angstrom, c = 6.657 Angstrom, and that for the cubic crystal is a = 3.596 Angstrom. The X-ray photoelectron spectra of the B-C-N compound indicate the presence of B-N, C-N, C-C, and B-C bonds, which suggests that boron, carbon, and nitrogen atoms all bond with one another and that the B-C-N crystal is a compound in which the three kinds of atoms are mixed atomically. The composition of the B-C-N compound is B0.47C0.23N0.30. A strong absorption band at 1000similar to1120cm(-1) attributable to the cubic B-C-N phase is observed in the infrared spectrum, The photoluminescence spectrum of hexagonal B-C-N powder measured at room temperature features a broad peak centered at 374 nin, corresponding to the band-edge emission of h-B-C-N, and is similar to that of w-GaN.

  19. Effects of hydrogen on diamond single crystal synthesized under high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Li, Yong; Jia, Xiaopeng; Song, Mousheng; Ma, Hong-An; Zhou, Zhenxiang; Fang, Chao; Wang, Fangbiao; Chen, Ning; Wang, Ying

    2015-09-01

    In this paper, diamond single crystals doped with LiH and boron additives were synthesized in Fe64Ni36-C system under high pressure and high temperature. Under the fixed pressure condition, we found that the synthesis temperature increased slightly after the addition of LiH in the synthesis system. The {100}-orientated surface morphology was investigated by scanning electron microscopy (SEM). The nitrogen concentration in the obtained diamond was analyzed and evaluated using Fourier transmission infrared spectroscopy (FTIR). Furthermore, the electrical properties of Ib-type and boron-doped diamond before and after hydrogenation using Hall effect measurement, which suggested that the conductivity of diamond co-doped with hydrogen and boron was obviously enhanced than that of boron-doped diamond.

  20. An agile high-capacity FDMA digital satellite network

    NASA Astrophysics Data System (ADS)

    Hawkins, R. B.; Johannes, V. I.; Lowell, R.

    A centrally controlled digital transmission satellite network has been designed for High Speed Switched Digital Service (HSSDS), which uses both satellite and earth transmission facilities to provide point-to-point digital trunks on a reservation basis. HSSDS customers connect via 1.544 Mb/s loops to the nodes where switches are located, and the FDMA system employed offers 24 one-way 1.544 Mb/s trunks per satellite transponder.

  1. An Inexpensive, Very High Impedance Digital Voltmeter for Selective Electrodes.

    ERIC Educational Resources Information Center

    Caceci, Marco S.

    1984-01-01

    Describes a compact, digital voltmeter which exceeds, both in accuracy and input impedance, most commercial pH meters and potentiometers. The instrument consists of two parts: a very high impedance hybrid operational amplifier used as a voltage follower (ICH8500/A, Intersil) and a four and one-half digits LED display panel meter (RP-4500,…

  2. Digital valve for high pressure high flow applications

    NASA Astrophysics Data System (ADS)

    Badescu, Mircea; Sherrit, Stewart; Lewis, Derek; Bao, Xiaoqi; Bar-Cohen, Yoseph; Hall, Jeffery L.

    2016-04-01

    To address the challenges, which are involved with the development of flow control valves that can meet high demand requirements such as high pressure, high flow rate, limited power and limited space, the authors have conceived a novel design configuration. This design consists of a digitalized flow control valve with multipath and multistage pressure reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet. A choke valve controls the total flow rate by digitally opening different paths or different combination of the paths. Each path is controlled by a poppet cap valve basically operated in on-off states. The number of flow states is 2N where N is the number of flow paths. To avoid erosion from sand in the fluid and high speed flow, the seal area of the poppet cap valve is located at a distance from the flow inlet away from the high speed flow and the speed is controlled to stay below a predefined erosion safe limit. The path is a multistage structure composed of a set of serial nozzles-expansion chambers that equally distribute the total pressure drop to each stage. The pressure drop of each stage and, therefore, the flow speed at the nozzles and expansion chambers is controlled by the number of stages. The paths have relatively small cross section and could be relatively long for large number of stages and still fit in a strict annular space limit. The paper will present the design configuration, analysis and preliminary test results.

  3. Highly integrated digital electronic control: Digital flight control, aircraft model identification, and adaptive engine control

    NASA Technical Reports Server (NTRS)

    Baer-Riedhart, Jennifer L.; Landy, Robert J.

    1987-01-01

    The highly integrated digital electronic control (HIDEC) program at NASA Ames Research Center, Dryden Flight Research Facility is a multiphase flight research program to quantify the benefits of promising integrated control systems. McDonnell Aircraft Company is the prime contractor, with United Technologies Pratt and Whitney Aircraft, and Lear Siegler Incorporated as major subcontractors. The NASA F-15A testbed aircraft was modified by the HIDEC program by installing a digital electronic flight control system (DEFCS) and replacing the standard F100 (Arab 3) engines with F100 engine model derivative (EMD) engines equipped with digital electronic engine controls (DEEC), and integrating the DEEC's and DEFCS. The modified aircraft provides the capability for testing many integrated control modes involving the flight controls, engine controls, and inlet controls. This paper focuses on the first two phases of the HIDEC program, which are the digital flight control system/aircraft model identification (DEFCS/AMI) phase and the adaptive engine control system (ADECS) phase.

  4. Solid-state reactions to synthesize nanostructured lead selenide semiconductor powders by high-energy milling

    SciTech Connect

    Rojas-Chavez, H.

    2011-10-15

    Highlights: {yields} PbSe synthesized from PbO instead of Pb powder do not require an inert atmosphere. {yields} During high-energy milling oxygen has to be chemically reduced from the lead oxide. {yields} Solid-state and solid-gas chemical reactions promote both solid and gaseous products. -- Abstract: Both solid-solid and gas-solid reactions have been traced during high-energy milling of Se and PbO powders under vial (P, T) conditions in order to synthesize the PbSe phase. Chemical and thermodynamic arguments are postulated to discern the high-energy milling mechanism to transform PbO-Se micropowders onto PbSe-nanocrystals. A set of reactions were evaluated at around room temperature. Therefore an experimental campaign was designed to test the nature of reactions in the PbO-Se system during high-energy milling.

  5. Development of high precision digital driver of acoustic-optical frequency shifter for ROG

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Kong, Mei; Xu, Yameng

    2016-10-01

    We develop a high precision digital driver of the acoustic-optical frequency shifter (AOFS) based on the parallel direct digital synthesizer (DDS) technology. We use an atomic clock as the phase-locked loop (PLL) reference clock, and the PLL is realized by a dual digital phase-locked loop. A DDS sampling clock up to 320 MHz with a frequency stability as low as 10-12 Hz is obtained. By constructing the RF signal measurement system, it is measured that the frequency output range of the AOFS-driver is 52-58 MHz, the center frequency of the band-pass filter is 55 MHz, the ripple in the band is less than 1 dB@3MHz, the single channel output power is up to 0.3 W, the frequency stability is 1 ppb (1 hour duration), and the frequency-shift precision is 0.1 Hz. The obtained frequency stability has two orders of improvement compared to that of the analog AOFS-drivers. For the designed binary frequency shift keying (2-FSK) and binary phase shift keying (2-PSK) modulation system, the demodulating frequency of the input TTL synchronous level signal is up to 10 kHz. The designed digital-bus coding/decoding system is compatible with many conventional digital bus protocols. It can interface with the ROG signal detecting software through the integrated drive electronics (IDE) and exchange data with the two DDS frequency-shift channels through the signal detecting software.

  6. High performance 14-bit pipelined redundant signed digit ADC

    NASA Astrophysics Data System (ADS)

    Narula, Swina; Pandey, Sujata

    2016-03-01

    A novel architecture of a pipelined redundant-signed-digit analog to digital converter (RSD-ADC) is presented featuring a high signal to noise ratio (SNR), spurious free dynamic range (SFDR) and signal to noise plus distortion (SNDR) with efficient background correction logic. The proposed ADC architecture shows high accuracy with a high speed circuit and efficient utilization of the hardware. This paper demonstrates the functionality of the digital correction logic of 14-bit pipelined ADC at each 1.5 bit/stage. This prototype of ADC architecture accounts for capacitor mismatch, comparator offset and finite Op-Amp gain error in the MDAC (residue amplification circuit) stages. With the proposed architecture of ADC, SNDR obtained is 85.89 dB, SNR is 85.9 dB and SFDR obtained is 102.8 dB at the sample rate of 100 MHz. This novel architecture of digital correction logic is transparent to the overall system, which is demonstrated by using 14-bit pipelined ADC. After a latency of 14 clocks, digital output will be available at every clock pulse. To describe the circuit behavior of the ADC, VHDL and MATLAB programs are used. The proposed architecture is also capable of reducing the digital hardware. Silicon area is also the complexity of the design.

  7. Synthesize and characterization of graphene nanosheets with high surface area and nano-porous structure

    NASA Astrophysics Data System (ADS)

    Jabari Seresht, Razieh; Jahanshahi, Mohsen; Rashidi, Alimorad; Ghoreyshi, Ali Asghar

    2013-07-01

    A few-layer graphene was obtained by the expansion and exfoliation of water-intercalated graphene oxide via heat treatment in nitrogen environment in the temperature range of 200-1000 °C. Graphene which was synthesized at 800 °C (GT800) had a higher quality than other temperatures. This graphene has a high specific surface area (560.6 m2 g-1) and nano-porous structure. However, as for the purpose of comparison, graphene was synthesized with a colloidal suspension of exfoliated graphene oxide sheets in water with hydrazine hydrate in various reaction times (12, 24 and 36 h). This method has obtained a six-layer graphene and graphene that was synthesized during 24 h reaction with hydrazine hydrate (GC24) had a higher quality in comparison with the other products. The GC24 had 195.97 m2 g-1 specific surface area and nano-porous structure. The as-synthesized graphene were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) as well as BET measurements. The results demonstrated that this low-cost method for few-layer grapheme, e.g. three-layers, fabrication is reliable and promising.

  8. Digital control of high-intensity acoustic testing

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.

    1975-01-01

    To eliminate previous system instabilities and control high-intensity acoustic tests, a digital control vibration test system is modified by a software change. Three systems for the control of acoustic testing are compared: a hybrid digital/analog system, a digital vibration system, and the same digital vibration system modified by a software change to allow acoustic testing. It is shown that the hybrid system and the modified vibration system exhibit almost equal performance, although the hybrid system performs testing twice as fast. The development of a specialized acoustic test control system is justified since it costs far less than the general-purpose vibration control system. However, the latter is much easier to set up for a test, which is important in preventing overtesting of valuable spacecraft components.

  9. High speed 3D surface inspection with digital holography

    NASA Astrophysics Data System (ADS)

    Brunn, Andreas; Aspert, Nicolas; Cuche, Etienne; Emery, Yves; Ettemeyer, Andreas

    2013-01-01

    Digital holography has proven its ability to acquire high accuracy full field 3D data with one single image acquisition. This means that in principle this technique offers the chance to perform 3D serial inspection processes, as well. However, one limitation in digital holography is its limited ability to measure rough surfaces. In the presence of rough surfaces, the magnification of the image has to be increased to capture the required phase information on each camera pixel. However, this leads to significant reduction of inspection speed. If low magnification is selected, the rough surface produces speckles which cannot be treated properly by digital holography algorithms. In this paper, we describe the extension of digital holography to rough surface applications using speckle interferometry technique. This technique is capable of fast inspection of rough surfaces with sub-micrometer accuracy. The principle of this approach is shown and a practical application for 3D surface inspection of wafer cutting processes is given.

  10. Understanding Digital-Synthesized Photographs through Theories of Knowledge: A Case Study of Tom Bamberger's "Cultured Landscapes"

    ERIC Educational Resources Information Center

    Huang, Yi-hui

    2011-01-01

    With the rapid advancement of technology in the photographic industry, more photographers than ever (willingly or in response to this shift) are replacing their darkroom-based facilities with digital ones. This technological shift has changed the focus of the artmaking process in that photographers now spend more time editing their photographs…

  11. 3D SERS imaging based on chemically-synthesized highly-symmetric nanoporous silver microparticles

    NASA Astrophysics Data System (ADS)

    Ozaki, Yukihiro; Vantasin, Sanpon; Ji, Wei; Tanaka, Yoshito; Kitahama, Yasutaka; Wongrawee, Kanet; Ekgasit, Sanong

    2016-09-01

    This study presents the synthesis, SERS properties in three dimensions, and an application of 3D symmetric nanoporous silver microparticles. The particles are synthesized by purely chemical process: controlled precipitation of AgCl to acquire highly symmetric AgCl microparticle, followed by in-place to convert AgCl into nanoporous silver. The particles display highly predictable SERS enhancement pattern in three dimensions, which resembles particle shape and retains symmetry. The highly regular enhancement pattern allows an application in the study of inhomogeneity in two-layer polymer system, by improving spatial resolution in Z axis.

  12. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    SciTech Connect

    Zhang, Lei Chen, Haibin E-mail: mejswu@ust.hk; Wu, Jingshen E-mail: mejswu@ust.hk; Bi, Xianghong

    2014-05-15

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence.

  13. High Temperature Measurements Of Martensitic transformations Using Digital Holography

    SciTech Connect

    Thiesing, Benjamin; Mann, Christopher J; Dryepondt, Sebastien N

    2013-01-01

    During thermal cycling of nickel-aluminum-platinum (NiAlPt) and single crystal Fe-15Cr-15Ni alloys, the structural changes associated with the martensite to austenite phase transformation were measured using dual-wavelength digital holography. Real-time in-situ measurements reveal the formation of striations within the NiPtAl alloy at 70 C and the FeCrNi alloy at 520 C. The results demonstrate that digital holography is an effective technique for acquiring non-contact, high precision information of the surface evolution of alloys at high temperatures.

  14. High temperature measurements of martensitic transformations using digital holography.

    PubMed

    Thiesing, Benjamin P; Mann, Christopher J; Dryepondt, Sebastien

    2013-07-01

    During thermal cycling of nickel-aluminum-platinum (NiAlPt) and single crystal iron-chromium-nickel (FeCrNi) alloys, the structural changes associated with the martensite to austenite phase transformation were measured using dual-wavelength digital holography. Real-time in situ measurements reveal the formation of striations within the NiAlPt alloy at 70°C and the FeCrNi alloy at 520°C. The results demonstrate that digital holography is an effective technique for acquiring noncontact, high precision information of the surface evolution of alloys at high temperatures.

  15. Insect wing deformation measurements using high speed digital holographic interferometry.

    PubMed

    Aguayo, Daniel D; Mendoza Santoyo, Fernando; De la Torre-I, Manuel H; Salas-Araiza, Manuel D; Caloca-Mendez, Cristian; Gutierrez Hernandez, David Asael

    2010-03-15

    An out-of-plane digital holographic interferometry system is used to detect and measure insect's wing micro deformations. The in-vivo phenomenon of the flapping is registered using a high power cw laser and a high speed camera. A series of digital holograms with the deformation encoded are obtained. Full field deformation maps are presented for an eastern tiger swallowtail butterfly (Pterourus multicaudata). Results show no uniform or symmetrical deformations between wings. These deformations are in the order of hundreds of nanometers over the entire surface. Out-of-plane deformation maps are presented using the unwrapped phase maps.

  16. Digitally Controlled High Availability Power Supply

    SciTech Connect

    MacNair, David; /SLAC

    2008-09-25

    This paper reports the design and test results on novel topology, high-efficiency, and low operating temperature, 1,320-watt power modules for high availability power supplies. The modules permit parallel operation for N+1 redundancy with hot swap capability. An embedded DSP provides intelligent start-up and shutdown, output regulation, general control and fault detection. PWM modules in the DSP drive the FET switches at 20 to 100 kHz. The DSP also ensures current sharing between modules, synchronized switching, and soft start up for hot swapping. The module voltage and current have dedicated ADCs (>200 kS/sec) to provide pulse-by-pulse output control. A Dual CAN bus interface provides for low cost redundant control paths. Over-rated module components provide high reliability and high efficiency at full load. Low on-resistance FETs replace conventional diodes in the buck regulator. Saturable inductors limit the FET reverse diode current during switching. The modules operate in a two-quadrant mode, allowing bipolar output from complimentary module groups. Controllable, low resistance FETs at the input and output provide fault isolation and allow module hot swapping.

  17. Digital approach to high rate gamma-ray spectrometry

    SciTech Connect

    Korolczuk, Stefan; Mianowski, Slawomir; Rzadkiewicz, Jacek; Sibczynski, Pawel; Swiderski, Lukasz; Szewinski, Jaroslaw; Zychor, Izabella

    2015-07-01

    Basic concepts and preliminary results of creating high rate digital spectrometry system using efficient ADCs and latest FPGA are presented as well as a comparison with commercially available devices. The possibility to use such systems, coupled to scintillators, in plasma experiments is discussed. (authors)

  18. Digitizing Practical Production Work for High-Stakes Assessments

    ERIC Educational Resources Information Center

    Newhouse, C. Paul; Tarricone, Pina

    2014-01-01

    High-stakes external assessment for practical courses is fraught with problems impacting on the manageability, validity and reliability of scoring. Alternative approaches to assessment using digital technologies have the potential to address these problems. This paper describes a study that investigated the use of these technologies to create and…

  19. High Temperature Strain Measurements Using Digital Optics

    DTIC Science & Technology

    1991-09-01

    Eae Melting and Boiling Temperatures for Several Metals ................ 3 2 Comparison of Micrometer and Camera Readings at Room Temperature...over-all accuracy. For materials at or near melting or ablation temperatures any contact with the test sample is an undesirable and often unacceptable... melting and boiling temperatures for several metals 3. In addition to high metals, carbon in the form of graphite sublimes at temperatures near 7000’F in

  20. Generation of high-dynamic range image from digital photo

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Potemin, Igor S.; Zhdanov, Dmitry D.; Wang, Xu-yang; Cheng, Han

    2016-10-01

    A number of the modern applications such as medical imaging, remote sensing satellites imaging, virtual prototyping etc use the High Dynamic Range Image (HDRI). Generally to obtain HDRI from ordinary digital image the camera is calibrated. The article proposes the camera calibration method based on the clear sky as the standard light source and takes sky luminance from CIE sky model for the corresponding geographical coordinates and time. The article considers base algorithms for getting real luminance values from ordinary digital image and corresponding programmed implementation of the algorithms. Moreover, examples of HDRI reconstructed from ordinary images illustrate the article.

  1. High-throughput screening of microchip-synthesized genes in programmable double-emulsion droplets.

    PubMed

    Chan, H F; Ma, S; Tian, J; Leong, K W

    2017-03-09

    The rapid advances in synthetic biology and biotechnology are increasingly demanding high-throughput screening technology, such as screening of the functionalities of synthetic genes for optimization of protein expression. Compartmentalization of single cells in water-in-oil (W/O) emulsion droplets allows screening of a vast number of individualized assays, and recent advances in automated microfluidic devices further help realize the potential of droplet technology for high-throughput screening. However these single-emulsion droplets are incompatible with aqueous phase analysis and the inner droplet environment cannot easily communicate with the external phase. We present a high-throughput, miniaturized screening platform for microchip-synthesized genes using microfluidics-generated water-in-oil-in-water (W/O/W) double emulsion (DE) droplets that overcome these limitations. Synthetic gene variants of fluorescent proteins are synthesized with a custom-built microarray inkjet synthesizer, which are then screened for expression in Escherichia coli (E. coli) cells. Bacteria bearing individual fluorescent gene variants are encapsulated as single cells into DE droplets where fluorescence signals are enhanced by 100 times within 24 h of proliferation. Enrichment of functionally-correct genes by employing an error correction method is demonstrated by screening DE droplets containing fluorescent clones of bacteria with the red fluorescent protein (rfp) gene. Permeation of isopropyl β-d-1-thiogalactopyranoside (IPTG) through the thin oil layer from the external solution initiates target gene expression. The induced expression of the synthetic fluorescent proteins from at least ∼100 bacteria per droplet generates detectable fluorescence signals to enable fluorescence-activated cell sorting (FACS) of the intact droplets. This technology obviates time- and labor-intensive cell culture typically required in conventional bulk experiment.

  2. Thermoelectric properties of high pressure synthesized lithium and calcium double-filled CoSb3

    NASA Astrophysics Data System (ADS)

    Li, Xiaohui; Kang, Yulong; Chen, Chen; Li, Jianghua; Zhang, Long; Yu, Fengrong; Yu, Dongli; Tian, Yongjun; Xu, Bo

    2017-01-01

    Lithium and calcium are inefficient filling elements of CoSb3 at ambient pressure, but show nice filling behavior under high pressure. In this work, we synthesized Li/Ca double-filled CoSb3 with high pressure synthesis method. The products show the skutterudite structure of Im3 ¯ symmetry. Thermoelectric properties were effectively enhanced through Li and Ca co-filling. For the optimal Li0.08Ca0.18Co4Sb12 sample, the power factor maintains a relatively high value over the whole measurement temperature range and peaks at 4700 μ Wm-1K-2 , meanwhile the lattice thermal conductivity is greatly suppressed, leading to a maximal ZT of 1.18 at 700 K. Current work demonstrates high pressure synthesis as an effective method to produce multiple elemental filled CoSb3 skutterudites.

  3. Multiplexed chirp waveform synthesizer

    DOEpatents

    Dudley, Peter A.; Tise, Bert L.

    2003-09-02

    A synthesizer for generating a desired chirp signal has M parallel channels, where M is an integer greater than 1, each channel including a chirp waveform synthesizer generating at an output a portion of a digital representation of the desired chirp signal; and a multiplexer for multiplexing the M outputs to create a digital representation of the desired chirp signal. Preferably, each channel receives input information that is a function of information representing the desired chirp signal.

  4. Direct drive digital servo press with high parallel control

    NASA Astrophysics Data System (ADS)

    Murata, Chikara; Yabe, Jun; Endou, Junichi; Hasegawa, Kiyoshi

    2013-12-01

    Direct drive digital servo press has been developed as the university-industry joint research and development since 1998. On the basis of this result, 4-axes direct drive digital servo press has been developed and in the market on April of 2002. This servo press is composed of 1 slide supported by 4 ball screws and each axis has linearscale measuring the position of each axis with high accuracy less than μm order level. Each axis is controlled independently by servo motor and feedback system. This system can keep high level parallelism and high accuracy even with high eccentric load. Furthermore the 'full stroke full power' is obtained by using ball screws. Using these features, new various types of press forming and stamping have been obtained by development and production. The new stamping and forming methods are introduced and 'manufacturing' need strategy of press forming with high added value and also the future direction of press forming are also introduced.

  5. Characterization and Compensation of High Speed Digitizers

    SciTech Connect

    Fong, P; Teruya, A; Lowry, M

    2005-04-04

    Increasingly, ADC technology is being pressed into service for single single-shot instrumentation applications that were formerly served by vacuum-tube based oscilloscopes and streak cameras. ADC technology, while convenient, suffers significant performance impairments. Thus, in these demanding applications, a quantitative and accurate representation of these impairments is critical to an understanding of measurement accuracy. We have developed a phase-plane behavioral model, implemented it in SIMULINK and applied it to interleaved, high-speed ADCs (up to 4 gigasamples/sec). We have also developed and demonstrated techniques to effectively compensate for these impairments based upon the model.

  6. Digitally Controlled High Availability Power Supply

    SciTech Connect

    MacNair, David; /SLAC

    2009-05-07

    This paper will report on the test results of a prototype 1320 watt power module for a high availability power supply. The module will allow parallel operation for N+1 redundancy with hot swap capability. The two quadrant output of each module allows pairs of modules to provide a 4 quadrant (bipolar) operation. Each module employs a novel 4 FET buck regulator arranged in a bridge configuration. Each side of the bridge alternately conducts through a small saturable ferrite that limits the reverse current in the FET body diode during turn off. This allows hard switching of the FETs with low switching losses. The module is designed with over-rated components to provide high reliability and better then 97% efficiency at full load. The modules use a Microchip DSP for control, monitoring, and fault detection. The switching FETS are driven by PWM modules in the DSP at 60 KHz. A Dual CAN bus interface provides for low cost redundant control paths. The DSP will also provide current sharing between modules, synchronized switching, and soft start up for hot swapping. The input and output of each module have low resistance FETs to allow hot swapping and isolation of faulted units.

  7. The application of high-speed digital image correlation.

    SciTech Connect

    Reu, Phillip L.; Miller, Timothy J.

    2008-02-01

    Digital image correlation (DIC) is a method of using digital images to calculate two-dimensional displacement and deformation or for stereo systems three-dimensional shape, displacement, and deformation. While almost any imaging system can be used with DIC, there are some important challenges when working with the technique in high- and ultra-high-speed applications. This article discusses three of these challenges: camera sensor technology, camera frame rate, and camera motion mitigation. Potential solutions are treated via three demonstration experiments showing the successful application of high-speed DIC for dynamic events. The application and practice of DIC at high speeds, rather than the experimental results themselves, provide the main thrust of the discussion.

  8. High Precision Digital Frequency Signal Source Based on FPGA

    NASA Astrophysics Data System (ADS)

    Yanbin, SHI; Jian, GUO; Ning, CUI

    The realization method of DDS technology is introduced, and its superior technical characteristics are analyzed in this paper. According to its characteristics, the high accuracy digital frequency signal source based on FPGA is designed. The simulation result indicated, compares with the traditional signal source, this type of signal source realized by the method of FPGA+DDS have many merits such as high precision and fast switch speed, which can satisfies the developing tendency of test facility.

  9. A high-performance digital system for electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Cui, Ziqiang; Wang, Huaxiang; Chen, Zengqiang; Xu, Yanbin; Yang, Wuqiang

    2011-05-01

    This paper describes a recently developed digital-based data acquisition system for electrical capacitance tomography (ECT). The system consists of high-capacity field-programmable gate arrays (FPGA) and fast data conversion circuits together with a specific signal processing method. In this system, digital phase-sensitive demodulation is implemented. A specific data acquisition scheme is employed to deal with residual charges in each measurement, resulting in a high signal-to-noise ratio (SNR) at high excitation frequency. A high-speed USB interface is employed between the FPGA and a host PC. Software in Visual C++ has been developed to accomplish operational functions. Various tests were performed to evaluate the system, e.g. frame rate, SNR, noise level, linearity, and static and dynamic imaging. The SNR is 60.3 dB at 1542 frames s-1 for a 12-electrode sensor. The mean absolute error between the measured capacitance and the linear fit value is 1.6 fF. The standard deviation of the measurements is in the order of 0.1 fF. The dynamic imaging test demonstrates the advantages of high temporal resolution of the system. The experimental results indicate that the digital signal processing devices can be used to construct a high-performance ECT system.

  10. Titanium-rich highly ordered mesoporous silica synthesized by using a mixed surfactant system

    NASA Astrophysics Data System (ADS)

    Chandra, Debraj; Kishor Mal, Nawal; Mukherjee, Manabendra; Bhaumik, Asim

    2006-06-01

    A new titanium-rich highly ordered 2-D hexagonal mesoporous titanium silicate has been synthesized using a mixture of cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (Brij-35, C 12H 25-(OC 2H 4) 23-OH, a polyether and aliphatic hydrocarbon chain surfactant) mixed surfactant system as the supramolecular structure directing agent (SDA) in the presence of tartaric acid (TA) as a mineralizer of Ti(IV). XRD, N 2 adsorption and TEM data suggested the presence of mesophase with hexagonal pore arrangements and the UV-visible, FT IR and XPS studies suggested the incorporation of mostly tetrahedral titanium (IV) species in the highly ordered silica network. This mesoporous titanium silicate material showed excellent catalytic activity and selectivity in the epoxidation of styrene using dilute aqueous H 2O 2 as oxidant.

  11. Electrical and galvanomagnetic properties of cadmium telluride films synthesized under highly nonequilibrium conditions

    SciTech Connect

    Belyaev, A. P. Rubets, V. P.; Antipov, V. V.; Grishin, V. V.

    2008-11-15

    The results of experimental studies of electrical and galvanomagnetic properties of CdTe films synthesized under highly nonequilibrium conditions via vapor condensation on a substrate cooled with liquid nitrogen are reported. The temperature dependences of dark conductivity, current-voltage characteristics with and without illumination, temperature dependences of the Hall coefficient R{sub H} and effective Hall mobility {mu}{sub H} in the planar geometry, and dark current-voltage characteristics in the sandwich geometry are reported. Anisotropy of conductivity is revealed. It is shown that the electrical and galvanomagnetic properties of the films are consistently described by a percolation model of charge transport, according to which, at high temperatures, the charge transport takes place over the percolation level of the valence band, and at low temperatures, over the percolation level of the impurity band.

  12. High-throughput syntheses of iron phosphite open frameworks in ionic liquids

    NASA Astrophysics Data System (ADS)

    Wang, Zhixiu; Mu, Ying; Wang, Yilin; Bing, Qiming; Su, Tan; Liu, Jingyao

    2017-02-01

    Three open-framework iron phosphites: Feп5(NH4)2(HPO3)6 (1), Feп2Fe♯(NH4)(HPO3)4 (2) and Fe♯2(HPO3)3 (3) have been synthesized under ionothermal conditions. How the different synthesis parameters, such as the gel concentrations, synthetic times, reaction temperatures and solvents affect the products have been monitored by using high-throughput approaches. Within each type of experiment, relevant products have been investigated. The optimal reaction conditions are obtained from a series of experiments by high-throughput approaches. All the structures are determined by single-crystal X-ray diffraction analysis and further characterized by PXRD, TGA and FTIR analyses. Magnetic study reveals that those three compounds show interesting magnetic behavior at low temperature.

  13. Butterflies' wings deformations using high speed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Mendoza Santoyo, Fernando; Aguayo, Daniel D.; de La Torre-Ibarra, Manuel H.; Salas-Araiza, Manuel D.

    2011-08-01

    A variety of efforts in different scientific disciplines have tried to mimic the insect's in-flight complex system. The gained knowledge has been applied to improve the performance of different flying artifacts. In this research report it is presented a displacement measurement on butterflies' wings using the optical noninvasive Digital Holographic Interferometry technique with out of plane sensitivity, using a high power cw laser and a high speed CMOS camera to record the unrepeatable displacement movements on these organic tissues. A series of digital holographic interferograms were recorded and the experimental results for several butterflies during flapping events. The relative unwrapped phase maps micro-displacements over the whole wing surface are shown in a wire-mesh representation. The difference between flying modes is remarkably depicted among them.

  14. Generalized syntheses of nanocrystal-graphene hybrids in high-boiling-point organic solvents.

    PubMed

    Pang, Danny Wei-Ping; Yuan, Fang-Wei; Chang, Yan-Cheng; Li, Guo-An; Tuan, Hsing-Yu

    2012-08-07

    Nanocrystal-graphene have been proposed as a new kind of promising hybrid for a wide range of application areas including catalysts, electronics, sensors, biomedicine, and energy storage, etc. Although a variety of methods have been developed for the preparation of hybrids, a facile and general synthetic approach is still highly required. In this study, nanocrystal-graphene hybrids were successfully synthesized in high-boiling-point organic solvents. Graphene oxide (GO) nanosheets were modified by oleylamine (OLA) to form a OLA-GO complex in order to be readily incorporated into hydrophobic synthesis. A rich library of highly crystalline nanocrystals, with types including noble metal, metal oxide, magnetic material and semiconductor were successfully grown on chemically converted graphene (CCG), which is simultaneously reduced from GO during the synthesis. High boiling-point solvents afford sufficient thermal energy to assure the high-quality crystalline nature of NCs, therefore the post-annealing process is obviated. Controlled experiments revealed that OLA-GO triggers heterogeneous nucleation and serves as excellent nuclei anchorage media. The protocol developed here brings one step closer to achieve "unity in diversity" on the preparation of nanocrystal-graphene hybrids.

  15. Synthesization of high-capacity auto-associative memories using complex-valued neural networks

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Jiao; Wang, Xiao-Yan; Long, Hai-Xia; Yang, Xu-Hua

    2016-12-01

    In this paper, a novel design procedure is proposed for synthesizing high-capacity auto-associative memories based on complex-valued neural networks with real-imaginary-type activation functions and constant delays. Stability criteria dependent on external inputs of neural networks are derived. The designed networks can retrieve the stored patterns by external inputs rather than initial conditions. The derivation can memorize the desired patterns with lower-dimensional neural networks than real-valued neural networks, and eliminate spurious equilibria of complex-valued neural networks. One numerical example is provided to show the effectiveness and superiority of the presented results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503338, 61573316, 61374152, and 11302195) and the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ15F030005).

  16. High-Voltage Digital-To-Analog Converter

    NASA Technical Reports Server (NTRS)

    Huston, Steven W.

    1990-01-01

    High-voltage 10-bit digital-to-analog converter operates under computer control to put out voltages up to 500 V at currents up to 35 mA. Circuit includes high-voltage power supply used to generate high-voltage square wave at frequency set by computer at value between 0.2 Hz and 10 Hz. Used to drive 0.02-microfarad, 1-kV capacitor at slewing rate of 1 V/microsecond to provide signal for robotic imaging system.

  17. Observation of high coercive fields in chemically synthesized coated Fe-Pt nanostructures

    NASA Astrophysics Data System (ADS)

    Dalavi, Shankar B.; Panda, Rabi N.

    2017-04-01

    Nanocrystalline Fe-Pt alloys have been synthesized via chemical reduction route using various capping agents; such as: oleic acid/oleylamine (route-1) and oleic acid/CTAB (route-2). We could able to synthesize Fe50Pt and Fe54Pt alloys via route 1 and 2, respectively. As-prepared Fe-Pt alloys crystallize in disordered fcc phase with crystallite sizes of 2.3 nm and 6 nm for route-1 and route-2, respectively. Disordered Fe-Pt alloys were transformed to ordered fct phase after annealing at 600 °C. SEM studies confirm the spherical shape morphologies of annealed Fe-Pt nanoparticles with SEM particle sizes of 24.4 nm and 21.2 nm for route-1 and route-2, respectively. TEM study confirms the presence of 4.6 nm particles for annealed Fe50Pt alloys with several agglomerating clusters of bigger size and appropriately agrees well with the XRD study. Room temperature magnetization studies of as-prepared Fe-Pt alloys (fcc) show ferromagnetism with negligible coercivities. Average magnetic moments per particle for as-prepared Fe-Pt alloys were estimated to be 753 μB and 814 μB, for route 1 and 2, respectively. Ordered fct Fe-Pt alloys show high values of coercivities of 10,000 Oe and 10,792 Oe for route-1 and route-2, respectively. Observed magnetic properties of the fct Fe-Pt alloys nps were interpreted with the basis of order parameters, size, surface, and composition effects.

  18. Pyrolytic and oxidative syntheses of high-yield carbons from biomass

    NASA Astrophysics Data System (ADS)

    Dai, Xiangfeng

    A pressurized chemical reactor was designed and built per ASME code, which is capable of conducting pyrolysis, activation and gasification processes with an available volume of 7.2 L. It can operate at a pressure up to 3.5 MPa and the system provides a maximum saturated steam flow rate of 2.4 kg/hr at 5.4 MPa. With this reactor, the effects of moisture content, pressure and pretreatment of feedstock on synthesizing charcoal and its yields and properties were examined. Higher moisture content favors charcoal formation and leads to uniform properties of charcoal throughout the bed. However, it demands more external energy. Increase in operation pressure also favors higher yield of charcoal with reduced cook time, but not significantly for pressure above 1 MPa. Woods sorbed with CuSOsb4 and FeSOsb4 result in higher yield and/or better quality as well as short cook time. Charcoals from woods and nutshells have yields around 40% to 65% with a gross calorific value over 30 MJ/kg. A novel process for synthesizing high-yield activated carbon from Macshells was discovered, which involves air activation. Together with equations derived from energy balance, a model describing mass transport and reaction was developed for evaluating roles of diffusion in oxygenating biomass charcoal. Carbonization step is found necessary for subsequent oxygenation and activation in obtaining high-yield activated carbon. Both modeled and experimental results show no influence of mass transport in oxygenation at a temperature below 560 K, and good agreement in temperature rise due to reaction. Results from the kinetics model and the experiments indicate first-order reaction kinetics in oxygenation with respect to oxygen partial pressure. Evaluation on the values of increase in surface area (or iodine number) per carbon loss for activated carbon obtained by this process shows more effective use of carbon compared to the conventional method. Ultimate analyses show high carbon content and low ash

  19. Modified Noise Power Ratio testing of high resolution digitizers

    SciTech Connect

    McDonald, T.S.

    1994-05-01

    A broadband, full signal range, side-by-side (tandem) test method for estimating the internal noise performance of high resolution digitizers is described and illustrated. The technique involves a re-definition of the traditional Noise Power Ratio (NPR) test, a change that not only makes this test applicable to higher resolution systems than was previously practical, but also enhances its value and flexibility. Since coherence analysis is the basis of this new definition, and since the application of coherence procedures to high resolution data poses several problems, this report discusses these problems and their resolution.

  20. Highly biocompatible, nanocrystalline hydroxyapatite synthesized in a solvothermal process driven by high energy density microwave radiation

    PubMed Central

    Smolen, Dariusz; Chudoba, Tadeusz; Malka, Iwona; Kedzierska, Aleksandra; Lojkowski, Witold; Swieszkowski, Wojciech; Kurzydlowski, Krzysztof Jan; Kolodziejczyk-Mierzynska, Małgorzata; Lewandowska-Szumiel, Małgorzata

    2013-01-01

    A microwave, solvothermal synthesis of highly biocompatible hydroxyapatite (HAp) nanopowder was developed. The process was conducted in a microwave radiation field having a high energy density of 5 W/mL and over a time less than 2 minutes. The sample measurements included: powder X-ray diffraction, density, specific surface area, and chemical composition. The morphology and structure were investigated by scanning electron microscopy as well as transmission electron microscopy (TEM). The thermal behavior analysis was conducted using a simultaneous thermal analysis technique coupled with quadruple mass spectrometry. Additionally, Fourier transform infrared spectroscopy tests of heated samples were performed. A degradation test and a biocompatibility study in vitro using human osteoblast cells were also conducted. The developed method enables the synthesis of pure, fully crystalline hexagonal HAp nanopowder with a specific surface area close to 240 m2/g and a Ca/P molar ratio equal to 1.57. TEM measurements showed that this method results in particles with an average grain size below 6 nm. A 28-day degradation test conducted according to the ISO standard indicated a 22% loss of initial weight and a calcium ion concentration at 200 μmol/dm3 in the tris(hydroxymethyl)aminomethane hydrochloride test solution. The cytocompatibility of the obtained material was confirmed in a culture of human bone derived cells, both in an indirect test using the material extract, and in direct contact. A quantitative analysis was based on the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide. Viability assay as well as on DNA content measurements in the PicoGreen test. Indirect observations were performed at one point in time according to the ISO standard for in vitro cytotoxicity (ie, after 24 hours of cell exposure to the extracts). The direct contact tests were completed at three time points: after 24 hours, on day 7, and on day 14 of a culture in an osteogenic

  1. An All-Digital High Data-Rate Parallel Receiver

    NASA Astrophysics Data System (ADS)

    Srinivasan, M.; Chen, C.-C.; Grebowsky, G.; Gray, A.

    1997-07-01

    The all-digital, high data-rate parallel receiver that is currently being developed jointly by the Jet Propulsion Laboratory (JPL) and Goddard Space Flight Center (GSFC) is presented. The role of JPL has been to analyze and simulate the receiver architecture and subsystems. Implementation of the receiver using field-programmable gate arrays (FPGAs) and subsequent application-specific integrated circuit (ASIC) design take place at GSFC. The parallel receiver architecture that is currently being implemented differs from the original multirate filter-bank-based parallel architecture that was first developed by JPL. This alternate parallel receiver (APRX) is essentially a frequency-domain implementation of detection filtering and symbol-timing correction and is significantly easier to implement than the original version of the parallel receiver (PRX). It is shown that the APRX is equivalent to both the PRX and the conventional serial receiver in terms of performance. Results on the effect of analog antialiasing filter bandwidth and analog-to-digital sampling offset on the receiver performance are presented, along with discussion and results of the frequency-domain digital data-transition tracking-loop simulation.

  2. Applications for high-accuracy digital ionosonde data

    SciTech Connect

    Paul, A.K.

    1990-05-03

    The new technology used in modern digital ionosondes permits the measurement of traditional (virtual heights and amplitude of echoes) and new (radio phase of echoes) ionospheric data with very high precision. Consequently, higher accuracy for standard ionospheric parameters can be achieved and new types of parameters can be obtained using new processing methods. Details of such data analysis programs may depend on the type of digital ionosonde used; however, the basic physical principles involved are the same. For example, there is no doubt that the change of the radio phase with time is proportional to the Doppler frequency of the echo. In recent years much effort has gone into modeling of the ionosphere. Unfortunately the spatial and the temporal resolution of the most basic parameters of the data base for testing such models is inadequate. For example, it appears that in some areas (e.g., Europe) the spatial resolution of the F-layer maximum electron density may be sufficient, but this is not true for the height of the maximum and the half-thickness of the F-layer, since very few station computed electron density profiles from the recorded ionograms. In the following we will outline a new procedure for computing F-layer profile parameters. The process is simple and its routine application could significantly improve the data base. The accuracy limits of the resulting parameters will be discussed together with some other important ionospheric quantities observable with digital ionosondes.

  3. High Resolution Airborne Digital Imagery for Precision Agriculture

    NASA Technical Reports Server (NTRS)

    Herwitz, Stanley R.

    1998-01-01

    The Environmental Research Aircraft and Sensor Technology (ERAST) program is a NASA initiative that seeks to demonstrate the application of cost-effective aircraft and sensor technology to private commercial ventures. In 1997-98, a series of flight-demonstrations and image acquisition efforts were conducted over the Hawaiian Islands using a remotely-piloted solar- powered platform (Pathfinder) and a fixed-wing piloted aircraft (Navajo) equipped with a Kodak DCS450 CIR (color infrared) digital camera. As an ERAST Science Team Member, I defined a set of flight lines over the largest coffee plantation in Hawaii: the Kauai Coffee Company's 4,000 acre Koloa Estate. Past studies have demonstrated the applications of airborne digital imaging to agricultural management. Few studies have examined the usefulness of high resolution airborne multispectral imagery with 10 cm pixel sizes. The Kodak digital camera integrated with ERAST's Airborne Real Time Imaging System (ARTIS) which generated multiband CCD images consisting of 6 x 106 pixel elements. At the designated flight altitude of 1,000 feet over the coffee plantation, pixel size was 10 cm. The study involved the analysis of imagery acquired on 5 March 1998 for the detection of anomalous reflectance values and for the definition of spectral signatures as indicators of tree vigor and treatment effectiveness (e.g., drip irrigation; fertilizer application).

  4. Theoretical analysis of high-resolution digital mammography

    NASA Astrophysics Data System (ADS)

    Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan; Sechopoulos, Ioannis

    2006-06-01

    The performance of a high-resolution charge coupled device-based full-field digital mammography imager was analysed using a mathematical framework based on an adaptation of cascaded linear systems theory described by other investigators. This work has been conducted in order to understand the impact of various design parameters on the physical performance characteristics of the imager. Specifically, the effect of pixel size, scintillator thickness and packing density, x-ray spectra, air kerma, dark current, charge integration time, and pixel fill-factor on the frequency dependent detective quantum efficiency was studied using a charge-coupled device as a reference platform. The imaging system was modelled as a series of physical processes with gain and spatial spreading. For each stage, the signal and noise power spectra were computed and propagated through the imaging chain as inputs to subsequent stages. Good agreement between experimental and theoretical predictions was obtained for various x-ray spectral conditions that were investigated. The modulation transfer function, MTF(f) and detective quantum efficiency DQE(f) characteristics obtained in this study are encouraging and comparable to other digital mammography systems. The results of this study strongly suggest the feasibility of large area scintillator-based digital mammography imagers with pixel sizes below 100 µm.

  5. Flame and solution syntheses of high-dimensional homo- and hetero-structured nanomaterials

    NASA Astrophysics Data System (ADS)

    Dong, Zhizhong

    Tungsten-oxide and molybdenum-oxide nanostructures are fabricated directly from the surfaces of metal substrates using counter-flow diffusion-flame synthesis method, which allows for correlation of morphologies with local conditions. Computational simulations aid in tailoring the flame structure with respect to chemical species and temperature. Furthermore, methane flames are compared with hydrogen flames, which only have H2O (and no CO2) as product species. The temperature profiles of the methane and hydrogen flames are strategically matched in order to compare the effect of chemical species produced by the flame which serve as reactants for nanostructure growth. Single-crystalline, well-vertically-aligned, and dense WO2.9 nanowires (diameters of 20-50 nm, lengths of >10 microm) are obtained at a gas-phase temperature of 1720 K, where the CO2 route is presumed to seed the growth of nanowires at the nucleation stage, with subsequent vapor-solid growth. Similarly, single-crystalline, vertically-aligned, and dense MoO 2 nanoplates (thicknesses of 60-80 nm, widths of 200-450 nm, lengths of 1-2 microm) are obtained at 1720 K. Nanoheterostructures are fabricated by decorating/coating the above flame-synthesized tungsten-oxide nanowires with other materials using an aqueous solution synthesis method. With WO 2.9 nanowires serving as the scaffold, sequential growth of hexagonal ZnO nanoplates, Zn2SnO4 nanocubes, and SnO2 nanoparticles are attained for different Zn2+:Sn2+ concentration ratios. High-resolution transmission electron microscopy (HRTEM) of the interfaces at the nanoheterojunctions show atomically abrupt interfaces for ZnO/WO2.9 and Zn2SnO4/WO2.9, despite lattice mismatches. Separately, co-axial nanoheterostructures are fabricated using ionic-liquid solutions, where single-crystal nanoscale Al layer are electrodeposited on the surfaces of the above flame-synthesized WO2.9 nanowires. These tungsten-oxide/aluminum coaxial nanowire arrays constitute thermite

  6. High speed displacement analysis using digital speckle correlation

    NASA Astrophysics Data System (ADS)

    Siebert, T.; Splitthof, K.; Becker, T.; Krupka, R.

    2006-06-01

    Digital speckle correlation techniques have already been successfully proven for accurate displacement analysis. With the use of two cameras, three dimensional measurements of contours and displacements can be carried out. The principle of this technique is pretty easy to understood and realized, opening a nearly unlimited range of applications. Rapid new developments in the field of digital imaging and computer technology, especially for very much dynamic applications, opens further applications for these measurement method up to high speed deformation and strain analysis, e.g. in the fields of, material testing, fracture mechanics, high speed testing, advanced materials and component testing. The dynamic range is combined with the capability to measure very large strains (up to more than 100%). The resolution of the deformation in space and time opens a wide range of applications for vibration analysis of objects. Since the system determines the absolute position and displacements of the object in space it is capable of measuring high amplitudes and even objects with rigid body movements, which is a big advantage against full field ESPI systems. The absolute resolution depends on the field of view and is scalable. Calibration of the optical setup is a crucial point which will be discussed in detail. Examples of the analysis of high speed harmonic vibration and transient events out of material research and industrial applications are presented. Results of measurement performed on a vibrating membrane and a tensile test sample are show typical features of the system.

  7. Internal noise of a phase-locked receiver with a loop-controlled synthesizer

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    1979-01-01

    A local oscillator design that uses a digitally programmed frequency synthesizer instead of an analog VCO was proposed. The integral of the synthesizer input, the digital phase, is a convenient measure of integrated Doppler. The internal noise of such a receiver was examined. At high carrier margin, the local oscillator phase noise equals that of the Block IV receiver, about 2 deg rms at S-band, whereas the digital phase noise is about 0.5 deg rms.

  8. Josephson-based full digital bridge for high-accuracy impedance comparisons

    NASA Astrophysics Data System (ADS)

    Overney, Frédéric; Flowers-Jacobs, Nathan E.; Jeanneret, Blaise; Rüfenacht, Alain; Fox, Anna E.; Underwood, Jason M.; Koffman, Andrew D.; Benz, Samuel P.

    2016-08-01

    This paper describes a Josephson-based full digital impedance bridge capable of comparing any two impedances, regardless of type (R-C, R-L, or L-C), over a large frequency range (from 1 kHz to 20 kHz). At the heart of the bridge are two Josephson arbitrary waveform synthesizer systems that offer unprecedented flexibility in high-precision impedance calibration, that is, it can compare impedances with arbitrary ratios and phase angles. Thus this single bridge can fully cover the entire complex plane. In the near future, this type of instrument will considerably simplify the realization and maintenance of the various impedance scales in many National Metrology Institutes around the world. Contribution of the National Institute of Standards and Technology, US Department of Commerce, not subject to copyright in the United States.

  9. Automatic pole-zero/zero-pole digital compensator for high-resolution spectroscopy: Design and experiments

    SciTech Connect

    Geraci, A.; Pullia, A.; Ripamonti, G.

    1999-08-01

    In a high-resolution spectroscopy system the relatively long exponential decay due to the charge preamplifier is customarily canceled in an analogue fashion by means of a PZ (Pole-Zero) stage. The accurateness of such a compensation has a big impact on the energy resolution because it strongly affects the baseline-stability problems. The authors have automatically and on-line performed such a compensation in a digital way, while maintaining a spectroscopy performance and keeping at minimum both the ADC sampling frequency (thus power consumption) and its resolution (thus cost). This is done through an IIR filter, implemented within a FPGA by a DSP. The so-compensated waveform has, in excellent approximation, an all-pole shape. Starting from such a signal, the minimum-noise filters for energy and/or time measurements are then promptly synthesized and implemented for real time operation through the same DSP.

  10. Digital pressure transducer for use at high temperatures

    DOEpatents

    Karplus, H.H.B.

    A digital pressure sensor for measuring fluid pressures at relatively high temperatures includes an electrically conducting fiber coupled to the fluid by a force disc that causes tension in the fiber to be a function of fluid pressure. The tension causes changes in the mechanical resonant frequency of the fiber, which is caused to vibrate in a magnetic field to produce an electrical signal from a positive-feedback amplifier at the resonant frequency. A count of this frequency provides a measure of the fluid pressure.

  11. Digital pressure transducer for use at high temperatures

    DOEpatents

    Karplus, Henry H. B.

    1981-01-01

    A digital pressure sensor for measuring fluid pressures at relatively high temperatures includes an electrically conducting fiber coupled to the fluid by a force disc that causes tension in the fiber to be a function of fluid pressure. The tension causes changes in the mechanical resonant frequency of the fiber, which is caused to vibrate in a magnetic field to produce an electrical signal from a positive-feedback amplifier at the resonant frequency. A count of this frequency provides a measure of the fluid pressure.

  12. High current metal ion implantation to synthesize some conducting metal-silicides

    SciTech Connect

    Liu, B. X.; Gao, K. Y.

    1999-06-10

    High current metal-ion implantation by a metal vapor vacuum arc ion source was conducted to synthesize some conducting metal-silicides. It was found that C54-TiSi{sub 2}, ZrSi{sub 2}, NiSi{sub 2}, CoSi{sub 2}, {beta}-FeSi{sub 2}, NbSi{sub 2} and TaSi{sub 2} layers on Si wafers with good electric properties could be obtained directly after implantation. In comparison, the formation of some other silicides like {alpha}-FeSi{sub 2}, NbSi{sub 2}, TaSi{sub 2}, tetragonal-WSi{sub 2} and tetragonal-MoSi{sub 2} required an additional post-annealing to improve their crystallinity and thus their electric properties. Interestingly, the NiSi{sub 2} layers of superior electric properties were obtained at a selected Ni-ion current density of 35 {mu}A/cm{sup 2}. At this current, a beam heating raised the Si wafer to a specific temperature of 380 deg. C, at which the size difference between NiSi{sub 2} and Si lattices was nil. The resistivity of the NiSi{sub 2} layers so obtained was much lower than that of the Ni-disilicide formed by solid-state reaction at >750 deg. C. The formation mechanism of the above metal-silicides and the associated electric properties will also be discussed.

  13. Characterization of Al and Fe nanosized powders synthesized by high energy mechanical milling

    SciTech Connect

    Mhadhbi, Mohsen; Khitouni, Mohamed Azabou, Myriam; Kolsi, Abdelwaheb

    2008-07-15

    The process of nanocrystalline structure formation during mechanical milling was studied in Al and Fe powders. A detailed microstructural study of powder samples was carried out by X-ray diffraction experiments as a function of milling time. As a result, nanosized powders have been synthesized with microstructures showing a significant decrease of the coherent diffraction domains and the creation of a large number of linear defects, which induce microstrains. SEM results show that welding of very small particles to the surfaces of larger particles occurred and that the powder particles tended to form a matrix of randomly welded thin layers of highly deformed particles. Calorimetric measurements, as a function of milling time, indicated the decrease of the melting point of Al powder and at early stages it can be seen that initially endothermic peak was divided to two endothermic melting peaks. This is probably due to the oxide layer around the Al grains. In the case of Fe powder, the DSC measurements show a broad exothermal peak occurring over quite a large temperature interval, corresponding to the strain release and grain growth.

  14. A high-resolution multimode digital microscope system.

    PubMed

    Salmon, Edward D; Shaw, Sidney L; Waters, Jennifer C; Waterman-Storer, Clare M; Maddox, Paul S; Yeh, Elaine; Bloom, Kerry

    2013-01-01

    This chapter describes the development of a high-resolution, multimode digital imaging system based on a wide-field epifluorescent and transmitted light microscope, and a cooled charge-coupled device (CCD) camera. The three main parts of this imaging system are Nikon FXA microscope, Hamamatsu C4880 cooled CCD camera, and MetaMorph digital imaging system. This chapter presents various design criteria for the instrument and describes the major features of the microscope components-the cooled CCD camera and the MetaMorph digital imaging system. The Nikon FXA upright microscope can produce high resolution images for both epifluorescent and transmitted light illumination without switching the objective or moving the specimen. The functional aspects of the microscope set-up can be considered in terms of the imaging optics, the epi-illumination optics, the transillumination optics, the focus control, and the vibration isolation table. This instrument is somewhat specialized for microtubule and mitosis studies, and it is also applicable to a variety of problems in cellular imaging, including tracking proteins fused to the green fluorescent protein in live cells. The instrument is also valuable for correlating the assembly dynamics of individual cytoplasmic microtubules (labeled by conjugating X-rhodamine to tubulin) with the dynamics of membranes of the endoplasmic reticulum (labeled with DiOC6) and the dynamics of the cell cortex (by differential interference contrast) in migrating vertebrate epithelial cells. This imaging system also plays an important role in the analysis of mitotic mutants in the powerful yeast genetic system Saccharomyces cerevisiae.

  15. A high linearity downconverter for digital broadcasting system

    NASA Astrophysics Data System (ADS)

    Songting, Li; Jiancheng, Li; Xiaochen, Gu; Hongyi, Wang; Zhaowen, Zhuang

    2014-12-01

    An integrated downconverter with high linearity for digital broadcasting system receivers is implemented in a 0.13 μm CMOS process with an active area of 0.1 mm2. The current-mode scheme is adopted to improve linearity performance by avoiding voltage fluctuation. A passive CMOS switching pair is utilized to improve the even-order linearity of the downconverter. A current amplifier is used to provide low input impedance which will easily lead to a wide operating bandwidth and high linearity. Moreover, a current-mode Sallen-Key low-pass filter is adopted for effective rejection of out-of-band interferers and also low input impedance. The digital-assisted DC offset calibration improves the second-order distortion of the downconverter. This design achieves a maximum gain of 40 dB and a dynamic range of 10 dB. Measured noise figure is 8.2 dB, an IIP2 of 63 dBm, an IIP3 of 17 dBm at the minimum gain of 30 dB. The downconverter consumes about 7.7 mA under a supply of 1.2 V.

  16. High density monolithic packaging technology for digital/microwave avionics

    NASA Astrophysics Data System (ADS)

    Fertig, Timothy; Walter, Theresa; Gaver, Eric; Leahy, Kevin

    1994-10-01

    There has been a need for generic technologies and common approaches in design, development, and manufacturing of military and commercial products. This need is more pronounced and pressing today than ever before. With the objective to dramatically enhance avionics reliability, maintainability and availability (RM&A), an integrated, generic technology for packaging, cooling, and interconnection of high density and high performance circuits was developed. It is named High Density Monolithic Packaging (HDMP). Under the sponsorship of Wright Laboratory, a two-part complementary program (1990-1994), named Advanced Radio-Frequency Packaging/ARFP was contracted to Westinghouse. Under the ARFP program, the HDMP technology is being applied and its promising capability is being assessed for its ability to reduce the low power RF avionics life-cycle cost. Being better than half way through the program, the results and projections have been extremely promising. The technology assessment is approximately 50 percent complete and initial results have been extremely successful. Although the focus of the development effort has been on RF subsystems, the basic elements of HDMP technology have applications beyond RF/microwave subsystems. As digital processing speeds increase, RF/microwave design techniques must be applied to maintain high speed digital signal integrity. The basic elements of the HDMP technology are: low temperature co-fired ceramic (LTCC), solderless interconnects, multichip modules (MCM's), and composite heatsink materials. The key technology element, in this avionics availability enabling technology, is LTCC. LTCC material technology is a monolithic multilayered ceramic and conductor/metallization structure used as a substrate to support dense co-habitation of high density electronic circuits, their interconnections, and the electromechanical integrity of the integrated constituents.

  17. Study of the nanocrystalline bulk Al alloys synthesized by high energy mechanical milling followed by room temperature high pressing consolidation

    NASA Astrophysics Data System (ADS)

    Makhlouf, T.; Azabou, M.; Ghrib, M.; Ghrib, T.; Yacoubi, N.; Khitouni, M.

    2009-11-01

    In the present study high energy mechanical milling followed by high-pressing consolidation has been used to obtain bulk nanocrystalline Al-Fe-Si alloy. Quantitative XRD analysis and scanning electron microscopy were used to characterize the material evolution during thermal treatments in the temperature range 25- 500∘ C. The cold-worked structure have been synthesized with microstructure showing a mixture of a significant low size of crystallite (70 nm) and a high level of lattice strains (0.85%). Starting from the nanocrystalline specimens, isochronal experiments were carried out to monitor the reserve microstructure and transformations. The high temperature annealing is required for ameliorating the quality of room temperature consolidated materials by removing all porosity and obtaining good interparticle bonding. The thermal conductivity and the thermal diffusivity are investigated with the Photothermal deflection technique. These thermal parameters increase with the annealing temperatures. This behavior is attributed to the increase in the rate of diffusion coefficient of added elements inside the aluminum matrix.

  18. High Res at High Speed: Automated Delivery of High-Resolution Images from Digital Library Collections

    ERIC Educational Resources Information Center

    Westbrook, R. Niccole; Watkins, Sean

    2012-01-01

    As primary source materials in the library are digitized and made available online, the focus of related library services is shifting to include new and innovative methods of digital delivery via social media, digital storytelling, and community-based and consortial image repositories. Most images on the Web are not of sufficient quality for most…

  19. Digital acquisition system for high-speed 3-D imaging

    NASA Astrophysics Data System (ADS)

    Yafuso, Eiji

    1997-11-01

    High-speed digital three-dimensional (3-D) imagery is possible using multiple independent charge-coupled device (CCD) cameras with sequentially triggered acquisition and individual field storage capability. The system described here utilizes sixteen independent cameras, providing versatility in configuration and image acquisition. By aligning the cameras in nearly coincident lines-of-sight, a sixteen frame two-dimensional (2-D) sequence can be captured. The delays can be individually adjusted lo yield a greater number of acquired frames during the more rapid segments of the event. Additionally, individual integration periods may be adjusted to ensure adequate radiometric response while minimizing image blur. An alternative alignment and triggering scheme arranges the cameras into two angularly separated banks of eight cameras each. By simultaneously triggering correlated stereo pairs, an eight-frame sequence of stereo images may be captured. In the first alignment scheme the camera lines-of-sight cannot be made precisely coincident. Thus representation of the data as a monocular sequence introduces the issue of independent camera coordinate registration with the real scene. This issue arises more significantly using the stereo pair method to reconstruct quantitative 3-D spatial information of the event as a function of time. The principal development here will be the derivation and evaluation of a solution transform and its inverse for the digital data which will yield a 3-D spatial mapping as a function of time.

  20. High Resolution Spectroscopy Using a Tunable Thz Synthesizer Based on Photomixing

    NASA Astrophysics Data System (ADS)

    Cuisset, Arnaud; Hindle, Francis; Mouret, Gael; Eliet, Sophie; Guinet, Mickael; Bocquet, Robin

    2011-06-01

    Optical heterodyning, also know as photomixing is an attractive solution as a single device able to cover the entire frequency range from 300 GHz to 3 THz. As the THz frequency is extracted from the difference frequency of two lasers, the accuracy with which the generated frequency is known is directly determined by the frequency accuracy of the lasers. In order to fully characterize the spectral fingerprint of a given molecule an accuracy approximately one order of magnitude finer than the Doppler linewidth is required, around 100 kHz for smaller polar compounds. To generate accurate cw-THz the frequency spacing of the modes of a Frequency Comb (FC) has been employed to constrain the emission frequency of a photomixing source.footnote{G. Mouret, F. Hindle, A. Cuisset, C. Yang, R. Bocquet, M. Lours, D. Rovera, Opt. Express, 2009, 17: 22031.} Two phase locked loops are implemented coherently locking the two cw-lasers (CW1 and CW2) to different modes of the FC. Although this solution allows accurate generation of narrowband THz the continuous tuning of the frequency presents some obstacles. To overcome these difficulties a system architecture with a third cw-laser (CW3) phase locked to CW2 has been implemented. The beatnote between CW2 and CW3 is free from the FC modes therefore the PLL frequency can be freely scanned over its entire operating range, in our case around 200 MHz. The most of polar compounds may be studied at high resolution in the THz domain with this synthesizer. Three different examples of THz analysis with atmospherical and astrophysical interests will be presented: The ground and vibrationnally excited states of H_2CO revisited in the 0.5-2 THz frequency region The rotational dependences of the broadening coefficients of CH_3Cl studied at high J and K values The molecular discrimination of a complex mixture containing methanol and ethanol. F. Hindle, A. Cuisset, G. Mouret, R. Bocquet Comptes Rendus Physique, 2008, 9: 262-275.

  1. High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

    PubMed

    Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-11-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.

  2. A facilely synthesized amino-functionalized metal-organic framework for highly specific and efficient enrichment of glycopeptides.

    PubMed

    Zhang, Yi-Wei; Li, Ze; Zhao, Qiang; Zhou, Ying-Lin; Liu, Hu-Wei; Zhang, Xin-Xiang

    2014-10-09

    A facilely synthesized amino-functionalized metal-organic framework (MOF) MIL-101(Cr)-NH2 was first applied for highly specific glycopeptide enrichment based on the hydrophilic interactions. With the special characteristics of the MOF, the material performed well in selectivity and sensitivity for both standard glycoprotein samples and complex biological samples.

  3. Topology-Guided Design and Syntheses of Highly Stable Mesoporous Porphyrinic Zirconium Metal-Organic Frameworks with High Surface Area

    SciTech Connect

    Liu, TF; Feng, DW; Chen, YP; Zou, LF; Bosch, M; Yuan, S; Wei, ZW; Fordham, S; Wang, KC; Zhou, HC

    2015-01-14

    Through a topology-guided strategy, a series of Zr-6-containing isoreticular porphyrinic metalorganic frameworks (MOFs), PCN-228, PCN-229, and PCN-230, with ftw-a topology were synthesized using the extended porphyrinic linkers. The bulky porphyrin ring ligand effectively prevents the network interpenetration which often appears in MOFs with increased linker length. The pore apertures of the structures range from 2.5 to 3.8 nm, and PCN-229 demonstrates the highest porosity and BET surface area among the previously reported Zr-MOFs. Additionally, by changing the relative direction of the terminal phenyl rings, this series replaces a Zr-8 cluster with a smaller Zr-6 cluster in a topologically identical framework. The high connectivity of the Zr-6 cluster yields frameworks with enhanced stability despite high porosity and ultralarge linker. As a representative example, PCN-230, constructed with the most extended porphyrinic linker, shows excellent stability in aqueous solutions with pH values ranging from 0 to 12 and demonstrates one of the highest pH tolerances among all porphyrinic MOFs. This work not only presents a successful example of rational design of MOFs with desired topology, but also provides a strategy for construction of stable mesoporous MOFs.

  4. Topology-guided design and syntheses of highly stable mesoporous porphyrinic zirconium metal-organic frameworks with high surface area

    SciTech Connect

    Liu, Tian -Fu; Feng, Dawei; Chen, Ying -Pin; Zou, Lanfang; Bosch, Mathieu; Yuan, Shuai; Wei, Zhangwen; Fordham, Stephen; Wang, Kecheng; Zhou, Hong -Cai

    2015-01-14

    Through a topology-guided strategy, a series of Zr₆-containing isoreticular porphyrinic metal–organic frameworks (MOFs), PCN-228, PCN-229, and PCN-230, with ftw-a topology were synthesized using the extended porphyrinic linkers. The bulky porphyrin ring ligand effectively prevents the network interpenetration which often appears in MOFs with increased linker length. The pore apertures of the structures range from 2.5 to 3.8 nm, and PCN-229 demonstrates the highest porosity and BET surface area among the previously reported Zr-MOFs. Additionally, by changing the relative direction of the terminal phenyl rings, this series replaces a Zr₈ cluster with a smaller Zr₆ cluster in a topologically identical framework. The high connectivity of the Zr₆ cluster yields frameworks with enhanced stability despite high porosity and ultralarge linker. As a representative example, PCN-230, constructed with the most extended porphyrinic linker, shows excellent stability in aqueous solutions with pH values ranging from 0 to 12 and demonstrates one of the highest pH tolerances among all porphyrinic MOFs. This work not only presents a successful example of rational design of MOFs with desired topology, but also provides a strategy for construction of stable mesoporous MOFs.

  5. High-side Digitally Current Controlled Biphasic Bipolar Microstimulator

    PubMed Central

    Hanson, Timothy L.; Ómarsson, Björn; O'Doherty, Joseph E.; Peikon, Ian D.; Lebedev, Mikhail; Nicolelis, Miguel AL.

    2012-01-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware - without active artifact rejection - we are able to observe stimulus artifacts of less than 2 ms in duration. PMID:22328184

  6. High-side digitally current controlled biphasic bipolar microstimulator.

    PubMed

    Hanson, Timothy L; Ómarsson, Björn; O'Doherty, Joseph E; Peikon, Ian D; Lebedev, Mikhail A; Nicolelis, Miguel A L

    2012-05-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware-without active artifact rejection-we are able to observe stimulus artifacts of less than 2 ms in duration.

  7. Signed-Digit High Speed Transcendental Function Processor Architecture

    DTIC Science & Technology

    1989-06-01

    carry - select adder . A carry - select adder is used to...maximum value of their sum is Tmax + Xm,. = 9 + 1 = 10. The addition is accomplished by using the same carry - select adder described in the preceding...8217 from A by using the functions Ko = (A, xor A 4) and (73 or A4) 5-4 SIGNED-DIGIT INPUT A DIGIT B DIGIT 5-BIT CARRY - SELECT ADDER CARRY OUT 2 BIT

  8. High-resolution 3D digital models of artworks

    NASA Astrophysics Data System (ADS)

    Fontana, Raffaella; Gambino, Maria Chiara; Greco, Marinella; Pampaloni, Enrico; Pezzati, Luca; Scopigno, Roberto

    2003-10-01

    The measurement of the shape of an artwork usually requires a high-resolution instrumentation, in order to catch small details such as chisel marks, sculptural relieves, surface cracks, etc. 3D scanning techniques, together with new modeling software tools, allow a high fidelity reproduction of an artwork: these can be applied either to support and document its repair or for the realization of 3D archives and virtual museums. Starting from a high-resolution digital model of an object, a further step could be its reproduction by means of fast-prototyping techniques like stereo-lithography or electro-erosion. This work is aimed at showing the performance of a high-resolution laser scanner devoted to Cultural Heritage applications. The device is portable and very versatile, in order to allow in situ applications, accurate and reliable, so to capture intricate details. This laser profilometer has been used in a few surveys, the most significant of which are the monitoring the various phases of the restoration process of an ellenistic bronze (the Minerva of Arezzo, Florence), the cataloguing of some archaeological findings (from the Grotta della Poesia, Lecce) and the documenting of wooden panels surface conditions (the "Madonna del Cardellino" by Raffaello and "La Tebaide" by Beato Angelico).

  9. Highly efficient non-precious metal electrocatalysts prepared from one-pot synthesized zeolitic imidazolate frameworks.

    PubMed

    Zhao, Dan; Shui, Jiang-Lan; Grabstanowicz, Lauren R; Chen, Chen; Commet, Sean M; Xu, Tao; Lu, Jun; Liu, Di-Jia

    2014-02-01

    A facile synthesis of non-PGM ORR electrocatalysts through thermolysis of one-pot synthesized ZIF is demonstrated. The electrocatalysts exhibit excellent activity, with a maximum volumetric current density of 88.1 A cm(-3) measured at 0.8 V in PEFC tests. This approach not only makes ZIFs-based electrocatalysts easy to scale up, but also paves the way for the tailored synthesis of electrocatalysts.

  10. Synthesizing High-Frequency (1-25 HZ) Regional Phases at Large Distances (>1000 KM) Using Generalized Screen Propagators (GSP)

    DTIC Science & Technology

    2004-09-01

    seismology and earthquake seismology . The generalized screen propagator (GSP) is based on the one-way wave equation and the one-return approximation. The...High-Frequency (1-25 HZ) Regional Phases at Large Distances O (>1000 KM) Using Generalized Screen Propagators (GSP) SApproved for public release...DTRA 01-97-1-0004 Synthesizing High-Freguency (1-25 HZ) Regional Phases at Large Distances (1 > 1000 KM) Using Generalized Screen Propagators (GSP) 5b

  11. Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia.

    PubMed

    Forberg, Daniel; Schwob, Tobias; Zaheer, Muhammad; Friedrich, Martin; Miyajima, Nobuyoshi; Kempe, Rhett

    2016-10-20

    Large-scale energy storage and the utilization of biomass as a sustainable carbon source are global challenges of this century. The reversible storage of hydrogen covalently bound in chemical compounds is a particularly promising energy storage technology. For this, compounds that can be sustainably synthesized and that permit high-weight% hydrogen storage would be highly desirable. Herein, we report that catalytically modified lignin, an indigestible, abundantly available and hitherto barely used biomass, can be harnessed to reversibly store hydrogen. A novel reusable bimetallic catalyst has been developed, which is able to hydrogenate and dehydrogenate N-heterocycles most efficiently. Furthermore, a particular N-heterocycle has been identified that can be synthesized catalytically in one step from the main lignin hydrogenolysis product and ammonia, and in which the new bimetallic catalyst allows multiple cycles of high-weight% hydrogen storage.

  12. Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia

    PubMed Central

    Forberg, Daniel; Schwob, Tobias; Zaheer, Muhammad; Friedrich, Martin; Miyajima, Nobuyoshi; Kempe, Rhett

    2016-01-01

    Large-scale energy storage and the utilization of biomass as a sustainable carbon source are global challenges of this century. The reversible storage of hydrogen covalently bound in chemical compounds is a particularly promising energy storage technology. For this, compounds that can be sustainably synthesized and that permit high-weight% hydrogen storage would be highly desirable. Herein, we report that catalytically modified lignin, an indigestible, abundantly available and hitherto barely used biomass, can be harnessed to reversibly store hydrogen. A novel reusable bimetallic catalyst has been developed, which is able to hydrogenate and dehydrogenate N-heterocycles most efficiently. Furthermore, a particular N-heterocycle has been identified that can be synthesized catalytically in one step from the main lignin hydrogenolysis product and ammonia, and in which the new bimetallic catalyst allows multiple cycles of high-weight% hydrogen storage. PMID:27762267

  13. A New Dopant of NaN3 for High-Concentration-Nitrogen Diamond Synthesized by HPHT

    NASA Astrophysics Data System (ADS)

    Liang, Zhong-Zhu; Jia, Xiao-Peng; Hisao, Kanda; Ma, Hong-An; Wang, Dong-Mei; Liu, Wan-Qiang; Yu, Run-Ze

    2007-02-01

    Nitrogen is successfully doped in diamond by adding sodium azide (NaN3) as the source of nitrogen to the graphite and iron powders. The diamond crystals with high nitrogen concentration, 1000-2200 ppm, which contain the same concentrations of nitrogen with natural diamond, have been synthesized by using the system of iron-carbon-additive NaN3. The nitrogen concentrations in diamond increase with the increasing content of NaN3. When the content of NaN3 is increased to 0.7-1.3 wt.%, the nitrogen concentration in the diamond almost remains in a nitrogen concentration range from 1250 ppm to 2200 ppm, which is the highest value and several times higher than that in the diamond synthesized by a conventional method without additive NaN3 under high pressure and high temperature (HPHT) conditions.

  14. Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia

    NASA Astrophysics Data System (ADS)

    Forberg, Daniel; Schwob, Tobias; Zaheer, Muhammad; Friedrich, Martin; Miyajima, Nobuyoshi; Kempe, Rhett

    2016-10-01

    Large-scale energy storage and the utilization of biomass as a sustainable carbon source are global challenges of this century. The reversible storage of hydrogen covalently bound in chemical compounds is a particularly promising energy storage technology. For this, compounds that can be sustainably synthesized and that permit high-weight% hydrogen storage would be highly desirable. Herein, we report that catalytically modified lignin, an indigestible, abundantly available and hitherto barely used biomass, can be harnessed to reversibly store hydrogen. A novel reusable bimetallic catalyst has been developed, which is able to hydrogenate and dehydrogenate N-heterocycles most efficiently. Furthermore, a particular N-heterocycle has been identified that can be synthesized catalytically in one step from the main lignin hydrogenolysis product and ammonia, and in which the new bimetallic catalyst allows multiple cycles of high-weight% hydrogen storage.

  15. A gallium-arsenide digital phase shifter for clock and control signal distribution in high-speed digital systems

    NASA Technical Reports Server (NTRS)

    Fouts, Douglas J.

    1992-01-01

    The design, implementation, testing, and applications of a gallium-arsenide digital phase shifter and fan-out buffer are described. The integrated circuit provides a method for adjusting the phase of high-speed clock and control signals in digital systems, without the need for pruning cables, multiplexing between cables of different lengths, delay lines, or similar techniques. The phase of signals distributed with the described chip can be dynamically adjusted in eight different steps of approximately 60 ps per step. The IC also serves as a fan-out buffer and provides 12 in-phase outputs. The chip is useful for distributing high-speed clock and control signals in synchronous digital systems, especially if components are distributed over a large physical area or if there is a large number of components.

  16. High-performance VGA-resolution digital color CMOS imager

    NASA Astrophysics Data System (ADS)

    Agwani, Suhail; Domer, Steve; Rubacha, Ray; Stanley, Scott

    1999-04-01

    This paper discusses the performance of a new VGA resolution color CMOS imager developed by Motorola on a 0.5micrometers /3.3V CMOS process. This fully integrated, high performance imager has on chip timing, control, and analog signal processing chain for digital imaging applications. The picture elements are based on 7.8micrometers active CMOS pixels that use pinned photodiodes for higher quantum efficiency and low noise performance. The image processing engine includes a bank of programmable gain amplifiers, line rate clamping for dark offset removal, real time auto white balancing, per column gain and offset calibration, and a 10 bit pipelined RSD analog to digital converter with a programmable input range. Post ADC signal processing includes features such as bad pixel replacement based on user defined thresholds levels, 10 to 8 bit companding and 5 tap FIR filtering. The sensor can be programmed via a standard I2C interface that runs on 3.3V clocks. Programmable features include variable frame rates using a constant frequency master clock, electronic exposure control, continuous or single frame capture, progressive or interlace scanning modes. Each pixel is individually addressable allowing region of interest imaging and image subsampling. The sensor operates with master clock frequencies of up to 13.5MHz resulting in 30FPS. A total programmable gain of 27dB is available. The sensor power dissipation is 400mW at full speed of operation. The low noise design yields a measured 'system on a chip' dynamic range of 50dB thus giving over 8 true bits of resolution. Extremely high conversion gain result in an excellent peak sensitivity of 22V/(mu) J/cm2 or 3.3V/lux-sec. This monolithic image capture and processing engine represent a compete imaging solution making it a true 'camera on a chip'. Yet in its operation it remains extremely easy to use requiring only one clock and a 3.3V power supply. Given the available features and performance levels, this sensor will be

  17. Portable laser synthesizer for high-speed multi-dimensional spectroscopy

    DOEpatents

    Demos, Stavros G [Livermore, CA; Shverdin, Miroslav Y [Sunnyvale, CA; Shirk, Michael D [Brentwood, CA

    2012-05-29

    Portable, field-deployable laser synthesizer devices designed for multi-dimensional spectrometry and time-resolved and/or hyperspectral imaging include a coherent light source which simultaneously produces a very broad, energetic, discrete spectrum spanning through or within the ultraviolet, visible, and near infrared wavelengths. The light output is spectrally resolved and each wavelength is delayed with respect to each other. A probe enables light delivery to a target. For multidimensional spectroscopy applications, the probe can collect the resulting emission and deliver this radiation to a time gated spectrometer for temporal and spectral analysis.

  18. High fidelity, radiation tolerant analog-to-digital converters

    NASA Technical Reports Server (NTRS)

    Wang, Charles Chang-I (Inventor); Linscott, Ivan Richard (Inventor); Inan, Umran S. (Inventor)

    2012-01-01

    Techniques for an analog-to-digital converter (ADC) using pipeline architecture includes a linearization technique for a spurious-free dynamic range (SFDR) over 80 deciBels. In some embodiments, sampling rates exceed a megahertz. According to a second approach, a switched-capacitor circuit is configured for correct operation in a high radiation environment. In one embodiment, the combination yields high fidelity ADC (>88 deciBel SFDR) while sampling at 5 megahertz sampling rates and consuming <60 milliWatts. Furthermore, even though it is manufactured in a commercial 0.25-.mu.m CMOS technology (1 .mu.m=12.sup.-6 meters), it maintains this performance in harsh radiation environments. Specifically, the stated performance is sustained through a highest tested 2 megarad(Si) total dose, and the ADC displays no latchup up to a highest tested linear energy transfer of 63 million electron Volts square centimeters per milligram at elevated temperature (131 degrees C.) and supply (2.7 Volts, versus 2.5 Volts nominal).

  19. Fault tolerant, radiation hard, high performance digital signal processor

    NASA Technical Reports Server (NTRS)

    Holmann, Edgar; Linscott, Ivan R.; Maurer, Michael J.; Tyler, G. L.; Libby, Vibeke

    1990-01-01

    An architecture has been developed for a high-performance VLSI digital signal processor that is highly reliable, fault-tolerant, and radiation-hard. The signal processor, part of a spacecraft receiver designed to support uplink radio science experiments at the outer planets, organizes the connections between redundant arithmetic resources, register files, and memory through a shuffle exchange communication network. The configuration of the network and the state of the processor resources are all under microprogram control, which both maps the resources according to algorithmic needs and reconfigures the processing should a failure occur. In addition, the microprogram is reloadable through the uplink to accommodate changes in the science objectives throughout the course of the mission. The processor will be implemented with silicon compiler tools, and its design will be verified through silicon compilation simulation at all levels from the resources to full functionality. By blending reconfiguration with redundancy the processor implementation is fault-tolerant and reliable, and possesses the long expected lifetime needed for a spacecraft mission to the outer planets.

  20. High-speed digital fiber optic links for satellite traffic

    NASA Technical Reports Server (NTRS)

    Daryoush, A. S.; Ackerman, E.; Saedi, R.; Kunath, R. R.; Shalkhauser, K.

    1989-01-01

    Large aperture phased array antennas operating at millimeter wave frequencies are designed for space-based communications and imaging platforms. Array elements are comprised of active T/R modules which are linked to the central processing unit through high-speed fiber-optic networks. The system architecture satisfying system requirements at millimeter wave frequency is T/R level data mixing where data and frequency reference signals are distributed independently before mixing at the T/R modules. This paper demonstrates design procedures of a low loss high-speed fiber-optic link used for transmission of data signals over 600-900 MHz bandwidth inside satellite. The fiber-optic link is characterized for transmission of analog and digital data. A dynamic range of 79 dB/MHz was measured for analog data over the bandwidth. On the other hand, for bursted SMSK satellite traffic at 220 Mbps rates, BER of 2 x 10 to the -7th was measured for E(b)/N(o) of 14.3 dB.

  1. High-speed digital fiber optic links for satellite traffic

    NASA Astrophysics Data System (ADS)

    Daryoush, A. S.; Ackerman, E.; Saedi, R.; Kunath, R. R.; Shalkhauser, K.

    1989-09-01

    Large aperture phased array antennas operating at millimeter wave frequencies are designed for space-based communications and imaging platforms. Array elements are comprised of active T/R modules which are linked to the central processing unit through high-speed fiber-optic networks. The system architecture satisfying system requirements at millimeter wave frequency is T/R level data mixing where data and frequency reference signals are distributed independently before mixing at the T/R modules. This paper demonstrates design procedures of a low loss high-speed fiber-optic link used for transmission of data signals over 600-900 MHz bandwidth inside satellite. The fiber-optic link is characterized for transmission of analog and digital data. A dynamic range of 79 dB/MHz was measured for analog data over the bandwidth. On the other hand, for bursted SMSK satellite traffic at 220 Mbps rates, BER of 2 x 10 to the -7th was measured for E(b)/N(o) of 14.3 dB.

  2. Analysis of high-speed digital phonoscopy pediatric images

    NASA Astrophysics Data System (ADS)

    Unnikrishnan, Harikrishnan; Donohue, Kevin D.; Patel, Rita R.

    2012-02-01

    The quantitative characterization of vocal fold (VF) motion can greatly enhance the diagnosis and treatment of speech pathologies. The recent availability of high-speed systems has created new opportunities to understand VF dynamics. This paper presents quantitative methods for analyzing VF dynamics with high-speed digital phonoscopy, with a focus on expected VF changes during childhood. A robust method for automatic VF edge tracking during phonation is introduced and evaluated against 4 expert human observers. Results from 100 test frames show a subpixel difference between the VF edges selected by algorithm and expert observers. Waveforms created from the VF edge displacement are used to created motion features with limited sensitivity to variations of camera resolution on the imaging plane. New features are introduced based on acceleration ratios of critical points over each phonation cycle, which have the potential for studying issues related to impact stress. A novel denoising and hybrid interpolation/extrapolation scheme is also introduced to reduce the impact of quantization errors and large sampling intervals relative to the phonation cycle. Features extracted from groups of 4 adults and 5 children show large differences for features related to asymmetry between the right and left fold and consistent differences for impact acceleration ratio.

  3. Highly Luminescent Carbon Dots Synthesized by Microwave-Assisted Pyrolysis and Evaluation of Their Toxicity to Physa acuta.

    PubMed

    Sun, Xiaobo; Jin, Xiaozhe; Pan, Wei; Guo, Enmian; Liu, Weijian; Li, Denghui; Lu, Kunchao; Si, Shuxin; Zhang, Nianxing; Jia, Zhenzhen; Shi, Yanping; Li, Qianqian; Wang, Jinping

    2016-01-01

    As a newly emerging class of nanomaterials, carbon dots have increasingly attracted researchers' attention. However, their potentially adverse environmental effects are yet largely unknown. In this work, the highly luminescent carbon dots were synthesized by microwave-assisted pyrolysis of tris(hydroxymethyl)aminomethane (Tris) and citric acid. Then acute and chronic toxicities of carbon dots to Physa acuta (P. acuta), as well as their effect on reproduction, were evaluated using the as-synthesized dots as an example. The quantum yield of the as-synthesized carbon dots was up to 53.5% excited at 360 nm with the most fluorescent fraction of 82.6% after simple purification by gel column. The results showed that no acute but chronic toxicities to P. acuta exposed to different treatment concentrations of the as-synthesized carbon dots were observed with dose- dependence. In addition, the fecundity of P. acuta was promoted significantly by the carbon dots at the concentrations of 0.5 and 1.0 mg/mL, yet inhibited at the concentration of 3.0 mg/mL after 12-day exposure. Mainly distributing in the visceral mass might be responsible for the effects of the carbon dots on the survival and fecundity of P. acuta. And there was no further evidence to confirm that the carbon dots can cause malformation in developing embryos.

  4. A methodology for high resolution digital image correlation in high temperature experiments

    NASA Astrophysics Data System (ADS)

    Blaber, Justin; Adair, Benjamin S.; Antoniou, Antonia

    2015-03-01

    We propose a methodology for performing high resolution Digital Image Correlation (DIC) analysis during high-temperature mechanical tests. Specifically, we describe a technique for producing a stable, high-quality pattern on metal surfaces along with a simple optical system that uses a visible-range camera and a long-range microscope. The results are analyzed with a high-quality open-source DIC software developed by us. Using the proposed technique, we successfully acquired high-resolution strain maps of the crack tip field in a nickel superalloy sample at 1000 °C.

  5. Syntheses and properties of several metastable and stable hydrides derived from intermetallic compounds under high hydrogen pressure

    NASA Astrophysics Data System (ADS)

    Filipek, S. M.; Paul-Boncour, V.; Liu, R. S.; Jacob, I.; Tsutaoka, T.; Budziak, A.; Morawski, A.; Sugiura, H.; Zachariasz, P.; Dybko, K.; Diduszko, R.

    2016-12-01

    Brief summary of our former work on high hydrogen pressure syntheses of novel hydrides and studies of their properties is supplemented with new results. Syntheses and properties of a number of hydrides (unstable, metastable or stable in ambient conditions) derived under high hydrogen pressure from intermetallic compounds, like MeT2, MeNi5, Me7T3, Y6Mn23 and YMn12 (where Me = zirconium, yttrium or rare earth; T = transition metal) are presented. Stabilization of ZrFe2H4 due to surface phenomena was revealed. Unusual role of manganese in hydride forming processes is pointed out. Hydrogen induced phase transitions, suppression of magnetism, antiferromagnetic-ferromagnetic and metal-insulator or semimetal-metal transitions are described. Equations of state (EOS) of hydrides submitted to hydrostatic pressures up to 30 GPa are presented and discussed.

  6. Comparison of commercial iron oxide-based MRI contrast agents with synthesized high-performance MPI tracers.

    PubMed

    Lüdtke-Buzug, Kerstin; Haegele, Julian; Biederer, Sven; Sattel, Timo F; Erbe, Marlitt; Duschka, Robert L; Barkhausen, Jörg; Vogt, Florian M

    2013-12-01

    Magnetic particle imaging (MPI) recently emerged as a new tomographic imaging method directly visualizing the amount and location of superparamagnetic iron oxide particles (SPIOs) with high spatial resolution. To fully exploit the imaging performance of MPI, specific requirements are demanded on the SPIOs. Most important, a sufficiently high number of detectable harmonics of the receive signal spectrum is required. In this study, an assessment of commercial iron oxide-based MRI contrast agents is carried out, and the result is compared with that of a new self-synthesized high-performance MPI tracer. The decay of the harmonics is measured with a magnetic particle spectrometer (MPS). For the self-synthesized carboxymethyldextran-coated SPIO, it can be demonstrated that despite a small iron core diameter, the particle performance is as good as in Resovist, the best-performing commercial SPIO today. However, the self-synthesized particles show the lowest iron concentration compared with Resovist, Sinerem, and Endorem. As the iron dose will be an important issue in human MPI, the synthesis technique and the separation chain for self-synthesis will be pursued for further improvements. In evaluations carried out with MPS, it can be shown in this work that the quality of the self-synthesized nanoparticles outperforms the three commercial tracer materials when the decay of harmonics is normalized by the iron concentration. The results of this work emphasize the importance of producing highly uniform and monodisperse superparamagnetic particles contributing to lower application of tracer concentration, better sensitivity, or a higher spatial resolution.

  7. A highly active Pd-P nanoparticle electrocatalyst for enhanced formic acid oxidation synthesized via stepwise electroless deposition.

    PubMed

    Poon, Kee Chun; Khezri, Bahareh; Li, Yao; Webster, Richard D; Su, Haibin; Sato, Hirotaka

    2016-02-28

    A highly active Pd-P nanoparticle electrocatalyst for formic acid oxidation was synthesized using NaH2PO2 as the reducing agent. The Pd-P nanoparticles were amorphous and exhibited higher specific and mass activity values compared to commercial Pd/C electrocatalyts and reported literature values. Furthermore, the Pd-P nanoparticles were found to be more durable than Pd/C electrocatalyts.

  8. High efficiency digital cooler electronics for aerospace applications

    NASA Astrophysics Data System (ADS)

    Kirkconnell, C. S.; Luong, T. T.; Shaw, L. S.; Murphy, J. B.; Moody, E. A.; Lisiecki, A. L.; Ellis, M. J.

    2014-06-01

    Closed-cycle cryogenic refrigerators, or cryocoolers, are an enabling technology for a wide range of aerospace applications, mostly related to infrared (IR) sensors. While the industry focus has tended to be on the mechanical cryocooler thermo mechanical unit (TMU) alone, implementation on a platform necessarily consists of the combination of the TMU and a mating set of command and control electronics. For some applications the cryocooler electronics (CCE) are technologically simple and low cost relative to the TMU, but this is not always the case. The relative cost and complexity of the CCE for a space-borne application can easily exceed that of the TMU, primarily due to the technical constraints and cost impacts introduced by the typical space radiation hardness and reliability requirements. High end tactical IR sensor applications also challenge the state of the art in cryocooler electronics, such as those for which temperature setpoint and frequency must be adjustable, or those where an informative telemetry set must be supported, etc. Generally speaking for both space and tactical applications, it is often the CCE that limits the rated lifetime and reliability of the cryocooler system. A family of high end digital cryocooler electronics has been developed to address these needs. These electronics are readily scalable from 10W to 500W output capacity; experimental performance data for nominally 25W and 100W variants are presented. The combination of a FPGA-based controller and dual H-bridge motor drive architectures yields high efficiency (>92% typical) and precision temperature control (+/- 30 mK typical) for a wide range of Stirling-class mechanical cryocooler types and vendors. This paper focuses on recent testing with the AIM INFRAROT-MODULE GmbH (AIM) SX030 and AIM SF100 cryocoolers.

  9. An enhanced high-speed multi-digit BCD adder using quantum-dot cellular automata

    NASA Astrophysics Data System (ADS)

    Ajitha, D.; Ramanaiah, K. V.; Sumalatha, V.

    2017-02-01

    The advent of development of high-performance, low-power digital circuits is achieved by a suitable emerging nanodevice called quantum-dot cellular automata (QCA). Even though many efficient arithmetic circuits were designed using QCA, there is still a challenge to implement high-speed circuits in an optimized manner. Among these circuits, one of the essential structures is a parallel multi-digit decimal adder unit with significant speed which is very attractive for future environments. To achieve high speed, a new correction logic formulation method is proposed for single and multi-digit BCD adder. The proposed enhanced single-digit BCD adder (ESDBA) is 26% faster than the carry flow adder (CFA)-based BCD adder. The multi-digit operations are also performed using the proposed ESDBA, which is cascaded innovatively. The enhanced multi-digit BCD adder (EMDBA) performs two 4-digit and two 8-digit BCD addition 50% faster than the CFA-based BCD adder with the nominal overhead of the area. The EMDBA performs two 4-digit BCD addition 24% faster with 23% decrease in the area, similarly for 8-digit operation the EMDBA achieves 36% increase in speed with 21% less area compared to the existing carry look ahead (CLA)-based BCD adder design. The proposed multi-digit adder produces significantly less delay of (N –1) + 3.5 clock cycles compared to the N* One digit BCD adder delay required by the conventional BCD adder method. It is observed that as per our knowledge this is the first innovative proposal for multi-digit BCD addition using QCA.

  10. High speed analog-to-digital conversion with silicon photonics

    NASA Astrophysics Data System (ADS)

    Holzwarth, C. W.; Amatya, R.; Araghchini, M.; Birge, J.; Byun, H.; Chen, J.; Dahlem, M.; DiLello, N. A.; Gan, F.; Hoyt, J. L.; Ippen, E. P.; Kärtner, F. X.; Khilo, A.; Kim, J.; Kim, M.; Motamedi, A.; Orcutt, J. S.; Park, M.; Perrott, M.; Popovic, M. A.; Ram, R. J.; Smith, H. I.; Zhou, G. R.; Spector, S. J.; Lyszczarz, T. M.; Geis, M. W.; Lennon, D. M.; Yoon, J. U.; Grein, M. E.; Schulein, R. T.; Frolov, S.; Hanjani, A.; Shmulovich, J.

    2009-02-01

    Sampling rates of high-performance electronic analog-to-digital converters (ADC) are fundamentally limited by the timing jitter of the electronic clock. This limit is overcome in photonic ADC's by taking advantage of the ultra-low timing jitter of femtosecond lasers. We have developed designs and strategies for a photonic ADC that is capable of 40 GSa/s at a resolution of 8 bits. This system requires a femtosecond laser with a repetition rate of 2 GHz and timing jitter less than 20 fs. In addition to a femtosecond laser this system calls for the integration of a number of photonic components including: a broadband modulator, optical filter banks, and photodetectors. Using silicon-on-insulator (SOI) as the platform we have fabricated these individual components. The silicon optical modulator is based on a Mach-Zehnder interferometer architecture and achieves a VπL of 2 Vcm. The filter banks comprise 40 second-order microring-resonator filters with a channel spacing of 80 GHz. For the photodetectors we are exploring ion-bombarded silicon waveguide detectors and germanium films epitaxially grown on silicon utilizing a process that minimizes the defect density.

  11. Measurements of granular flow dynamics with high speed digital images

    SciTech Connect

    Lee, J.

    1994-12-31

    The flow of granular materials is common to many industrial processes. This dissertation suggests and validates image processing algorithms applied to high speed digital images to measure the dynamics (velocity, temperature and volume fraction) of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in the experiment. One technique utilizes block matching for spatially averaged velocity measurements of the glass particles. This technique is compared with the velocity measurement using an optic probe which is a conventional granular flow velocity measurement device. The other technique for measuring the velocities of individual acrylic particles is developed with correspondence using a Hopfield network. This technique first locates the positions of particles with pattern recognition techniques, followed by a clustering technique, which produces point patterns. Also, several techniques are compared for particle recognition: synthetic discriminant function (SDF), minimum average correlation energy (MACE) filter, modified minimum average correlation energy (MMACE) filter and variance normalized correlation. The author proposes an MMACE filter which improves generalization of the MACE filter by adjusting the amount of averaged spectrum of training images in the spectrum whitening stages of the MACE filter. Variance normalized correlation is applied to measure the velocity and temperature of flowing glass particles down the inclined chute. The measurements are taken for the steady and wavy flow and qualitatively compared with a theoretical model of granular flow.

  12. Characterization and Thermal Dehydration Kinetics of Highly Crystalline Mcallisterite, Synthesized at Low Temperatures

    PubMed Central

    Senberber, Fatma Tugce

    2014-01-01

    The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH)6)2·9(H2O)) mineral at low temperatures was characterized. For this purpose, several reaction temperatures (0–70°C) and reaction times (30–240 min) were studied. Synthesized minerals were subjected to X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Raman spectroscopies and scanning electron microscopy (SEM). Additionally, experimental analyses of boron trioxide (B2O3) content and reaction yields were performed. Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA) were used for the determination of thermal dehydration kinetics. According to the XRD results, mcallisterite, which has a powder diffraction file (pdf) number of “01-070-1902,” was formed under certain reaction parameters. Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30 min of reaction time, particle size was between 398.30 and 700.06 nm. Its B2O3 content and reaction yield were 50.80 ± 1.12% and 85.80 ± 0.61%, respectively. Finally, average activation energies (conversion values (α) that were selected between 0.1 and 0.6) were calculated as 100.40 kJ/mol and 98.31 kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS) methods, respectively. PMID:24719585

  13. Oxygen reduction reaction on highly-durable Pt/nanographene fuel cell catalyst synthesized employing in-liquid plasma

    NASA Astrophysics Data System (ADS)

    Amano, Tomoki; Kondo, Hiroki; Takeda, Keigo; Ishikawa, Kenji; Kano, Hiroyuki; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2016-09-01

    We recently have established ultrahigh-speed synthesis method of nanographene materials employing in-liquid plasma, and reported high durability of Pt/nanographene composites as a fuel cell catalyst. Crystallinity and domain size of nanographene materials were essential to their durability. However, their mechanism is not clarified yet. In this study, we investigated the oxygen reduction reaction using three-types of nanographene materials with different crystallinity and domain sizes, which were synthesized using ethanol, 1-propanol and 1-butanol, respectively. According to our previous studies, the nanographene material synthesized using the lower molecular weight alcohol has the higher crystallinity and larger domain size. Pt nanoparticles were supported on the nanographene surfaces by reducing 8 wt% H2PtCl6 diluted with H2O. Oxygen reduction current densities at a potential of 0.2 V vs. RHE were 5.43, 5.19 and 3.69 mA/cm2 for the samples synthesized using ethanol, 1-propanol and 1-butanol, respectively. This means that the higher crystallinity nanographene showed the larger oxygen reduction current density. The controls of crystallinity and domain size of nanographene materials are essential to not only their durability but also highly efficiency as catalyst electrodes.

  14. Development of human corneal epithelium on organized fibrillated transparent collagen matrices synthesized at high concentration.

    PubMed

    Tidu, Aurélien; Ghoubay-Benallaoua, Djida; Lynch, Barbara; Haye, Bernard; Illoul, Corinne; Allain, Jean-Marc; Borderie, Vincent M; Mosser, Gervaise

    2015-08-01

    Several diseases can lead to opacification of cornea requiring transplantation of donor tissue to restore vision. In this context, transparent collagen I fibrillated matrices have been synthesized at 15, 30, 60 and 90 mg/mL. The matrices were evaluated for fibril organizations, transparency, mechanical properties and ability to support corneal epithelial cell culture. The best results were obtained with 90 mg/mL scaffolds. At this concentration, the fibril organization presented some similarities to that found in corneal stroma. Matrices had a mean Young's modulus of 570 kPa and acellular scaffolds had a transparency of 87% in the 380-780 nm wavelength range. Human corneal epithelial cells successfully colonized the surface of the scaffolds and generated an epithelium with characteristics of corneal epithelial cells (i.e. expression of cytokeratin 3 and presence of desmosomes) and maintenance of stemness during culture (i.e. expression of ΔNp63α and formation of holoclones in colony formation assay). Presence of cultured epithelium on the matrices was associated with increased transparency (89%).

  15. Slow glucose release property of enzyme-synthesized highly branched maltodextrins differs among starch sources.

    PubMed

    Kittisuban, Phatcharee; Lee, Byung-Hoo; Suphantharika, Manop; Hamaker, Bruce R

    2014-07-17

    Seven types of starch (waxy corn, normal corn, waxy rice, normal rice, waxy potato, normal potato, and tapioca) were selected to produce slowly digestible maltodextrins by enzymatic modification using a previously developed procedure. Branching enzyme (BE) alone and in combination with β-amylase (BA) were used to increase the amount of α-1,6 branching points, which are slowly hydrolyzed by mucosal α-glucosidases in the small intestine. The enzymatic treatments of all starches resulted in a reduction of the debranched linear chain length distribution and weight-average molecular weight. After α-amylolysis of the enzymatically synthesized-maltodextrins, the proportion of branched α-limit dextrins increased, and consequently a reduction in rate of glucose release by rat intestinal α-glucosidases in vitro. Among the samples, enzyme-modified waxy starches had a more pronounced effect on an increase in the slow digestion property than normal starches. These enzyme-modified maltodextrins show potential as novel functional foods by slowing digestion rate to attain extended glucose release.

  16. Digital control of high-intensity acoustic testing. [for spacecraft

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.

    1975-01-01

    Three systems for the control of acoustic testing are compared: a hybrid digital/analog system, a digital vibration system, and the same digital vibration system modified by a software change. The hybrid system was constructed to control the 1/3-octaves from 50 to 1000 Hz. The vibration system was equipped with programs for sine and random vibration tests, shock analysis and synthesis, and signal analysis. For the modified vibration system, the random-vibration control program of the unmodified unit was changed so that acoustic tests could be performed. The performance of the three systems is compared by conducting probability-density and time-history analyses of the proposed test spectrum for the Mariner Jupiter/Saturn 1977 program. The results of the analyses show that the hybrid and modified vibration systems perform almost equally, but the modified vibration system is easier to use and produces better test documentation.

  17. High Resolution Digital Elevation Models of Pristine Explosion Craters

    NASA Technical Reports Server (NTRS)

    Farr, T. G.; Krabill, W.; Garvin, J. B.

    2004-01-01

    In order to effectively capture a realistic terrain applicable to studies of cratering processes and landing hazards on Mars, we have obtained high resolution digital elevation models of several pristine explosion craters at the Nevada Test Site. We used the Airborne Terrain Mapper (ATM), operated by NASA's Wallops Flight Facility to obtain DEMs with 1 m spacing and 10 cm vertical errors of 4 main craters and many other craters and collapse pits. The main craters that were mapped are Sedan, Scooter, Schooner, and Danny Boy. The 370 m diameter Sedan crater, located on Yucca Flat, is the largest and freshest explosion crater on Earth that was formed under conditions similar to hypervelocity impact cratering. As such, it is effectively pristine, having been formed in 1962 as a result of a controlled detonation of a 100 kiloton thermonuclear device, buried at the appropriate equivalent depth of burst required to make a simple crater. Sedan was formed in alluvium of mixed lithology and subsequently studied using a variety of field-based methods. Nearby secondary craters were also formed at the time and were also mapped by ATM. Adjacent to Sedan and also in alluvium is Scooter, about 90 m in diameter and formed by a high-explosive event. Schooner (240 m) and Danny Boy (80 m) craters were also important targets for ATM as they were excavated in hard basalt and therefore have much rougher ejecta. This will allow study of ejecta patterns in hard rock as well as engineering tests of crater and rock avoidance and rover trafficability. In addition to the high resolution DEMs, crater geometric characteristics, RMS roughness maps, and other higher-order derived data products will be generated using these data. These will provide constraints for models of landing hazards on Mars and for rover trafficability. Other planned studies will include ejecta size-frequency distribution at the resolution of the DEM and at finer resolution through air photography and field measurements

  18. Cellulose synthase complexes act in a concerted fashion to synthesize highly aggregated cellulose in secondary cell walls of plants.

    PubMed

    Li, Shundai; Bashline, Logan; Zheng, Yunzhen; Xin, Xiaoran; Huang, Shixin; Kong, Zhaosheng; Kim, Seong H; Cosgrove, Daniel J; Gu, Ying

    2016-10-04

    Cellulose, often touted as the most abundant biopolymer on Earth, is a critical component of the plant cell wall and is synthesized by plasma membrane-spanning cellulose synthase (CESA) enzymes, which in plants are organized into rosette-like CESA complexes (CSCs). Plants construct two types of cell walls, primary cell walls (PCWs) and secondary cell walls (SCWs), which differ in composition, structure, and purpose. Cellulose in PCWs and SCWs is chemically identical but has different physical characteristics. During PCW synthesis, multiple dispersed CSCs move along a shared linear track in opposing directions while synthesizing cellulose microfibrils with low aggregation. In contrast, during SCW synthesis, we observed swaths of densely arranged CSCs that moved in the same direction along tracks while synthesizing cellulose microfibrils that became highly aggregated. Our data support a model in which distinct spatiotemporal features of active CSCs during PCW and SCW synthesis contribute to the formation of cellulose with distinct structure and organization in PCWs and SCWs of Arabidopsis thaliana This study provides a foundation for understanding differences in the formation, structure, and organization of cellulose in PCWs and SCWs.

  19. Cellulose synthase complexes act in a concerted fashion to synthesize highly aggregated cellulose in secondary cell walls of plants

    PubMed Central

    Li, Shundai; Bashline, Logan; Zheng, Yunzhen; Xin, Xiaoran; Huang, Shixin; Kong, Zhaosheng; Kim, Seong H.; Cosgrove, Daniel J.; Gu, Ying

    2016-01-01

    Cellulose, often touted as the most abundant biopolymer on Earth, is a critical component of the plant cell wall and is synthesized by plasma membrane-spanning cellulose synthase (CESA) enzymes, which in plants are organized into rosette-like CESA complexes (CSCs). Plants construct two types of cell walls, primary cell walls (PCWs) and secondary cell walls (SCWs), which differ in composition, structure, and purpose. Cellulose in PCWs and SCWs is chemically identical but has different physical characteristics. During PCW synthesis, multiple dispersed CSCs move along a shared linear track in opposing directions while synthesizing cellulose microfibrils with low aggregation. In contrast, during SCW synthesis, we observed swaths of densely arranged CSCs that moved in the same direction along tracks while synthesizing cellulose microfibrils that became highly aggregated. Our data support a model in which distinct spatiotemporal features of active CSCs during PCW and SCW synthesis contribute to the formation of cellulose with distinct structure and organization in PCWs and SCWs of Arabidopsis thaliana. This study provides a foundation for understanding differences in the formation, structure, and organization of cellulose in PCWs and SCWs. PMID:27647923

  20. Well-Defined High Molecular Weight Polystyrene with High Rates and High Livingness Synthesized via Two-Stage RAFT Emulsion Polymerization.

    PubMed

    Yan, Kun; Gao, Xiang; Luo, Yingwu

    2015-07-01

    A highly living polymer with over 100 kg mol(-1) molecular weight is very difficult to achieve by controlled radical polymerization since the unavoidable side reactions of irreversible radical termination and radical chain transfer to monomer reaction become significant. It is reported that over 500 kg mol(-1) polystyrene with high livingness and low dispersity could be synthesized by a facile two-stage reversible addition-fragmentation transfer emulsion polymerization. The monomer conversion reaches 90% within 10 h. High livingness of the product is ascribed to the extremely low initiator concentration and the chain transfer constant for monomer unexpectedly much lower than the well-accepted values in the conventional radical polymerization. The two-stage monomer feeding policy much decreases the dispersity of the product.

  1. Evaluation of a high response electrohydraulic digital control valve

    NASA Technical Reports Server (NTRS)

    Anderson, R. L.

    1973-01-01

    The application is described of a digital control valve on an electrohydraulic servo actuator. The digital control problem is discussed in general as well as the design and evaluation of a breadboard actuator. The evaluation revealed a number of problems associated with matching the valve to a hydraulic load. The problems were related to lost motion resulting from bulk modulus and leakage. These problems were effectively minimized in the breadboard actuator by maintaining a 1000 psi back pressure on the valve circuit and thereby improving the effective bulk modulus.

  2. Using Digital Technologies to Improve the Authenticity of Performance Assessment for High-Stakes Purposes

    ERIC Educational Resources Information Center

    Newhouse, C. Paul

    2015-01-01

    This paper reports on the outcomes of a three-year study investigating the use of digital technologies to increase the authenticity of high-stakes summative assessment in four Western Australian senior secondary courses. The study involved 82 teachers and 1015 students and a range of digital forms of assessment using computer-based exams, digital…

  3. Surface structures of high-quality diamond crystals synthesized by the oxy-acetylene flame method

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Keiji; Amanuma, Shuji; Hirose, Yoichi

    1992-02-01

    The microstructures of the {111} surfaces of high-quality diamond crystals deposited by the oxy-acetylene flame method have been studied using a high-resolution scanning electron microscope to clear the mechanism of the crystal growth. On the {111} surfaces of the high-quality diamond crystals, the two-dimensional nucleation rate is suppressed and the two-dimensional crystal growth rate is promoted. The suppression of the two-dimensional nucleation rate and the promotion of the two-dimensional crystal growth rate reduce the number of faults, dislocations, and defects and result in the formation of high-quality diamond crystals.

  4. High-performance, nanostructure LiMnPO4/C composites synthesized via one-step solid state reaction

    NASA Astrophysics Data System (ADS)

    Zheng, Jugong; Ni, Liang; Lu, Yanwen; Qin, Cancan; Liu, Panxing; Wu, Tongfu; Tang, Yuefeng; Chen, Yanfeng

    2015-05-01

    LiMnPO4 is proposed as more promising cathode material as LiFePO4, while poor electronic conductivity and Jahn-Teller effects during charge/discharge processes hinder the electrochemical performance. To overcome these problems, one-step solid state reaction method is developed to synthesize LiMnPO4/C composites, which is with nanostructure, high crystallinity and good carbon coating. Manganese oxide sources and calcination temperature are investigated as factors for preparing high-performance LiMnPO4/C for Li-ion batteries. The results show that the LiMnPO4/C composites prepared with mixed manganese oxide deliver a superior initial capacity of 153 mAh g-1 at 0.05 C and high rate performance with discharge capacities of 123 mAh g-1 at 1 C and 103 mAh g-1 at 2 C. And the LiMnPO4/C composites synthesized at 600 °C can retain 94% of the initial capacity after 200 cycles at 1 C, revealing a stable cycling stability. Therefore, one-step solid state reaction brings to light the synthesis of high performance LiMnPO4/C cathode materials and is suitable for large scale production.

  5. Mössbauer study on the antiferromagnetic FeO synthesized under high pressure

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Takuro; Kanke, Yasushi; Yanagihara, Hideto; Kita, Eiji; Tsunoda, Yorihiko; Siratori, Kiiti; Kohn, Kay

    2012-03-01

    Mössbauer study and magnetic measurements were carried out on the stoichiometric FeO, prepared with the high pressure (˜5.5GPa) synthesis technique. Well known defects (Koch-Cohen clusters) in FeO are detected even in the stoichiometric specimen, prepared at high temperatures.

  6. High-precision three-dimensional shape reconstruction via digital refocusing in multi-wavelength digital holography.

    PubMed

    Xu, Li; Aleksoff, Carl C; Ni, Jun

    2012-05-20

    Three-dimensional (3D) shape reconstructions and metrology measurements are often limited by depth-of-field constraints. Current focus-detection-based techniques are insufficient to profile out-of-focus 3D objects with high axial accuracy. Extended-focus imaging (EFI) techniques can improve the range and precision of such measurements. By incorporating digital refocusing with multiwavelength interferometry, a holographic imaging solution is presented in this paper to accurately measure 3D objects over a large depth range. Accuracy and repeatability of the proposed EFI technique are validated by digital simulations and refocusing experiments. A reconstruction example demonstrates the feasibility of high-precision 3D measurements of objects deeper than the system's classical depth of field.

  7. Insights in High-Temperature Superconductivity from the Study of Films and Heterostructures Synthesized by Molecular Beam Epitaxy

    SciTech Connect

    Bozovic,I.

    2009-01-09

    Using molecular beam epitaxy, we synthesize atomically smooth thin films, multilayers and superlattices of cuprate high-temperature superconductors (HTS). Such heterostructures enable novel experiments that probe the basicphysics of HTS. For example, we have established that HTS and antiferromagnetic phases separate on Ångstrom scale, while the pseudo-gap state apparently mixes with HTS over an anomalously large length scale ('Giant Proximity Effect'). Here, we briefly review our most recent experiments on such films and superlattices. The new results include an unambiguous demonstration of strong coupling of in-plane charge excitations to out-of-plane lattice vibrations and the discovery of interface HTS.

  8. Novel uninterruptible self-determinate hybrid high-speed multimedia fiber optic wireless secure digital network

    NASA Astrophysics Data System (ADS)

    Lindsey, Lonnie

    2000-08-01

    One key to successful digital battlespace management is communications management. HF, UHF, VHF, CDMA, and SATCOM assets are difficult and complex to manage, and the modern digital battlespace adds new dimensions by including high volume multimedia transmissions, high-speed broadband data, and hyper-spectral sensor data. This environment requires more than the traditional voice transport-based communications system. The future sanctuary-based communication hub model will benefit from a novel uninterruptible self-determinate high bandwidth fiber optic system.

  9. Optical timing receiver for the NASA laser ranging system. Part 2: High precision time interval digitizer

    NASA Technical Reports Server (NTRS)

    Leskovar, B.; Turko, B.

    1977-01-01

    The development of a high precision time interval digitizer is described. The time digitizer is a 10 psec resolution stop watch covering a range of up to 340 msec. The measured time interval is determined as a separation between leading edges of a pair of pulses applied externally to the start input and the stop input of the digitizer. Employing an interpolation techniques and a 50 MHz high precision master oscillator, the equivalent of a 100 GHz clock frequency standard is achieved. Absolute accuracy and stability of the digitizer are determined by the external 50 MHz master oscillator, which serves as a standard time marker. The start and stop pulses are fast 1 nsec rise time signals, according to the Nuclear Instrument means of tunnel diode discriminators. Firing level of the discriminator define start and stop points between which the time interval is digitized.

  10. Method and apparatus for digitally based high speed x-ray spectrometer

    DOEpatents

    Warburton, William K.; Hubbard, Bradley

    1997-01-01

    A high speed, digitally based, signal processing system which accepts input data from a detector-preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system achieves high throughputs at low cost by dividing the required digital processing steps between a "hardwired" processor implemented in combinatorial digital logic, which detects the presence of the x-ray signals in the digitized data stream and extracts filtered estimates of their amplitudes, and a programmable digital signal processing computer, which refines the filtered amplitude estimates and bins them to produce the desired spectral analysis. One set of algorithms allow this hybrid system to match the resolution of analog systems while operating at much higher data rates. A second set of algorithms implemented in the processor allow the system to be self calibrating as well. The same processor also handles the interface to an external control computer.

  11. Method and apparatus for digitally based high speed x-ray spectrometer

    DOEpatents

    Warburton, W.K.; Hubbard, B.

    1997-11-04

    A high speed, digitally based, signal processing system which accepts input data from a detector-preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system achieves high throughputs at low cost by dividing the required digital processing steps between a ``hardwired`` processor implemented in combinatorial digital logic, which detects the presence of the x-ray signals in the digitized data stream and extracts filtered estimates of their amplitudes, and a programmable digital signal processing computer, which refines the filtered amplitude estimates and bins them to produce the desired spectral analysis. One set of algorithms allow this hybrid system to match the resolution of analog systems while operating at much higher data rates. A second set of algorithms implemented in the processor allow the system to be self calibrating as well. The same processor also handles the interface to an external control computer. 19 figs.

  12. Highly Sensitive Ethanol Sensor Based on Au-Decorated SnO2 Nanoparticles Synthesized Through Precipitation and Microwave Irradiation

    NASA Astrophysics Data System (ADS)

    Li, Yan; Zhao, Fang-Xian; Lian, Xiao-Xue; Zou, Yun-Ling; Wang, Qiong; Zhou, Qing-Jun

    2016-06-01

    Gold (Au)-decorated SnO2 nanoparticles (NPs) were synthesized through a precipitation and microwave irradiation process. The as-prepared products were characterized by x-ray diffraction and scanning electron microscopy. The results indicated that the as-prepared products consisted of nanometer-scale tetragonal crystalline SnO2 and face-centered cubic gold metal NPs. The gas sensing measurements showed that the sensor based on Au-decorated SnO2 NPs exhibited an extremely high response (239.5) toward 500-ppm ethanol at a relatively low working temperature (220°C). In addition, the response and recovery times of this sensor to ethanol were 1 s and 31 s, respectively. The excellent gas sensing performance of the synthesized NPs in terms of high response, fast response-recovery, superior selectivity, and good stability was attributed to the small nanometer size of the particles, Schottky barrier, and Au NP catalysis. Finally, we demonstrated that our Au-decorated SnO2 NPs could be a potential candidate for use in highly sensitive and selective gas sensors for ethanol.

  13. Microstructure and spectroscopy studies on cubic boron nitride synthesized under high-pressure conditions

    NASA Astrophysics Data System (ADS)

    Nistor, L. C.; Nistor, S. V.; Dinca, G.; Georgeoni, P.; Van Landuyt, J.; Manfredotti, C.; Vittone, E.

    2002-11-01

    High-resolution electron microscopy (HREM) studies of the microstructure and specific defects in hexagonal boron nitride (h-BN) precursors and cubic boron nitride (c-BN) crystals made under high-pressure high-temperature conditions revealed the presence of half-nanotubes at the edges of the h-BN particles. Their sp3 bonding tendency could strongly influence the nucleation rates of c-BN. The atomic resolution at extended dislocations was insufficient to allow us to determine the stacking fault energy in the c-BN crystals. Its mean value of 191 ± 15 mJ m-2 is of the same order of magnitude as that of diamond. High-frequency (94 GHz) electron paramagnetic resonance studies on c-BN single crystals have produced new data on the D1 centres associated with the boron species. Ion-beam-induced luminescence measurements have indicated that c-BN is a very interesting luminescent material, which is characterized by four luminescence bands and exhibits a better resistance to ionizing radiation than CVD diamond.

  14. Basement-membrane heparan sulphate with high affinity for antithrombin synthesized by normal and transformed mouse mammary epithelial cells.

    PubMed Central

    Pejler, G; David, G

    1987-01-01

    Basement-membrane proteoglycans, biosynthetically labelled with [35S]sulphate, were isolated from normal and transformed mouse mammary epithelial cells. Proteoglycans synthesized by normal cells contained mainly heparan sulphate and, in addition, small amounts of chondroitin sulphate chains, whereas transformed cells synthesized a relatively higher proportion of chondroitin sulphate. Polysaccharide chains from transformed cells were of lower average Mr and of lower anionic charge density compared with chains isolated from the untransformed counterparts, confirming results reported previously [David & Van den Berghe (1983) J. Biol. Chem. 258, 7338-7344]. A large proportion of the chains isolated from normal cells bound with high affinity to immobilized antithrombin, and the presence of 3-O-sulphated glucosamine residues, previously identified as unique markers for the antithrombin-binding region of heparin [Lindahl, Bäckström, Thunberg & Leder (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 6551-6555], could be demonstrated. A significantly lower proportion of the chains derived from transformed cells bound with high affinity to antithrombin, and a corresponding decrease in the amount of incorporated 3-O-sulphate was observed. PMID:2963617

  15. Precursor salt assisted syntheses of high-index faceted concave hexagon and nanorod-like polyoxometalates

    NASA Astrophysics Data System (ADS)

    Pal, Jaya; Ganguly, Mainak; Mondal, Chanchal; Negishi, Yuichi; Pal, Tarasankar

    2014-12-01

    This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into five distinctive shapes through straightforward and indirect routes. Explicit regulation of the structural arrangements of ACM and CMOH has been studied in detail with altered precursor salt concentration employing our laboratory developed modified hydrothermal (MHT) method. Morphologically different ACM 3D architectures are evolved with higher molybdate concentration, whereas 1D growth of CMOH is observed with increased copper concentration. Interesting morphological transformation of the products has been accomplished employing one precursor salt at a time without using any other foreign reagent. It has been proven that large ACMs become labile in the presence of incoming Cu(ii) and NH4+ ions of the precursor salts. A new strategy for the conversion of faceted ACMs (hexagonal plate, circular plate and hollow flower) to exclusive CMOH nanorods through a Cu(ii) assisted reaction has been adopted. According to thermodynamic consideration, the synthesis of rare concave nanostructures with high index facet is still challenging due to their higher reactivity. In this study, concave hexagonal ACM with high index facet {hkl} has been successfully prepared for the first time from hexagonal ACM through simple etching with ammonium heptamolybdate (AHM), which is another precursor salt. Hexagonal ACM corrugates to a concave hexagon because of the higher reactivity of the {001} crystal plane than that of the {010} plane. It has been shown that high index facet exposed concave hexagonal ACM serves as a better catalyst for the photodegradation of dye than the other microstructures enclosed by low index facets.This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into

  16. Precursor salt assisted syntheses of high-index faceted concave hexagon and nanorod-like polyoxometalates.

    PubMed

    Pal, Jaya; Ganguly, Mainak; Mondal, Chanchal; Negishi, Yuichi; Pal, Tarasankar

    2015-01-14

    This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into five distinctive shapes through straightforward and indirect routes. Explicit regulation of the structural arrangements of ACM and CMOH has been studied in detail with altered precursor salt concentration employing our laboratory developed modified hydrothermal (MHT) method. Morphologically different ACM 3D architectures are evolved with higher molybdate concentration, whereas 1D growth of CMOH is observed with increased copper concentration. Interesting morphological transformation of the products has been accomplished employing one precursor salt at a time without using any other foreign reagent. It has been proven that large ACMs become labile in the presence of incoming Cu(II) and NH4(+) ions of the precursor salts. A new strategy for the conversion of faceted ACMs (hexagonal plate, circular plate and hollow flower) to exclusive CMOH nanorods through a Cu(II) assisted reaction has been adopted. According to thermodynamic consideration, the synthesis of rare concave nanostructures with high index facet is still challenging due to their higher reactivity. In this study, concave hexagonal ACM with high index facet {hkl} has been successfully prepared for the first time from hexagonal ACM through simple etching with ammonium heptamolybdate (AHM), which is another precursor salt. Hexagonal ACM corrugates to a concave hexagon because of the higher reactivity of the {001} crystal plane than that of the {010} plane. It has been shown that high index facet exposed concave hexagonal ACM serves as a better catalyst for the photodegradation of dye than the other microstructures enclosed by low index facets.

  17. New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications

    NASA Astrophysics Data System (ADS)

    Guron, Marta

    There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly

  18. Synthesizing speech

    NASA Astrophysics Data System (ADS)

    Siltanen, Samuli

    2015-01-01

    Samuli Siltanen explains how solving an "inverse problem" will improve the quality of life of people who can't speak and have to use voice synthesizers - particularly women and children, whose only current option is to sound like an adult male.

  19. Waveform synthesizer

    DOEpatents

    Franks, Larry A.; Nelson, Melvin A.

    1981-01-01

    A method of producing optical and electrical pulses of desired shape. An optical pulse of arbitrary but defined shape illuminates one end of an array of optical fiber waveguides of differing lengths to time differentiate the input pulse. The optical outputs at the other end of the array are combined to form a synthesized pulse of desired shape.

  20. Systematic downgrading for investigating ``naturalness'' in synthesized singing using STRAIGHT: A high quality VOCODER

    NASA Astrophysics Data System (ADS)

    Kawahara, Hideki

    2002-05-01

    Conceptual simplicity of the classical channel VOCODER provides a powerful means for systematic investigations on perceptual effects of speech related physical parameters when combined with modern computational power and signal processing theories. A modern version of channel VOCODER, STRAIGHT [Kawahara et al., Speech Commun. 27, 187-207 (1999)], which is also an extension to pitch-synchronous analysis and synthesis, generates naturally sounding resynthesized speech from the analyzed smooth time-frequency surface and source parameters such as F0. This high-quality resynthesis enables close investigations on naturalness deterioration as a function of feature modifications in the decomposed parameter domain; for example, detailed shape of a F0 trajectory, underlying parameters to determine F0 trajectory dynamics, group delay alignment of excitation pulses and aperiodicity/periodicity ratio of the excitation source and so on. One of potential advantages of this strategy is based on the fact that our perceptual function is highly nonlinear. The other source of advantage is virtually an independent parameter set which allows precise control of parameter deviations from the original analysis results. An overview of recent findings and modification demonstrations will be presented. [Work supported by CREST grant of Japanese Science and Technology Corporation.

  1. High Transferability of Homoeolog-Specific Markers between Bread Wheat and Newly Synthesized Hexaploid Wheat Lines

    PubMed Central

    Zeng, Deying; Luo, Jiangtao; Li, Zenglin; Chen, Gang; Zhang, Lianquan; Ning, Shunzong; Yuan, Zhongwei; Zheng, Youliang; Hao, Ming; Liu, Dengcai

    2016-01-01

    Bread wheat (Triticum aestivum, 2n = 6x = 42, AABBDD) has a complex allohexaploid genome, which makes it difficult to differentiate between the homoeologous sequences and assign them to the chromosome A, B, or D subgenomes. The chromosome-based draft genome sequence of the ‘Chinese Spring’ common wheat cultivar enables the large-scale development of polymerase chain reaction (PCR)-based markers specific for homoeologs. Based on high-confidence ‘Chinese Spring’ genes with known functions, we developed 183 putative homoeolog-specific markers for chromosomes 4B and 7B. These markers were used in PCR assays for the 4B and 7B nullisomes and their euploid synthetic hexaploid wheat (SHW) line that was newly generated from a hybridization between Triticum turgidum (AABB) and the wild diploid species Aegilops tauschii (DD). Up to 64% of the markers for chromosomes 4B or 7B in the SHW background were confirmed to be homoeolog-specific. Thus, these markers were highly transferable between the ‘Chinese Spring’ bread wheat and SHW lines. Homoeolog-specific markers designed using genes with known functions may be useful for genetic investigations involving homoeologous chromosome tracking and homoeolog expression and interaction analyses. PMID:27611704

  2. Linear and star-shaped benzimidazolyl derivatives: syntheses, photophysical properties and use as highly efficient electron transport materials in OLEDs.

    PubMed

    White, Wade; Hudson, Zachary M; Feng, Xiaodong; Han, Sijin; Lu, Zheng-Hong; Wang, Suning

    2010-01-21

    Five benzimidazolyl functionalized linear and star-shaped molecules have been synthesized using Ullmann condensation methods. These molecules all possess deep LUMO energy levels and large HOMO-LUMO energy gaps ranging from 3.55 to 3.95 eV. All five compounds are fluorescent with emission in the UV region, and display high thermal and morphological stability. One of these star-shaped molecules, 2,4,5-tris(benzimidazolyl)-1,3,5-triazine, has been demonstrated to be a highly effective electron transport/hole blocking material in organic light emitting devices (OLEDs) with performance comparable to the commonly used electron transport material Alq(3) (q = 8-hydroxyquinolinate). In addition, metal ion titrations have established that these ligands show a distinct fluorescent response to the addition of Ag(I) or Zn(II) in solution.

  3. Effective Use of Digital Technologies of High School Teachers as Digital Immigrants in Six Rural Public Schools

    ERIC Educational Resources Information Center

    Pattee, Andy

    2012-01-01

    Problem: A widening experiential gap of effective use of technology in K-12 schools between "digital immigrants" and "digital natives" (Prensky, 2001) is becoming more evident as digital natives become classroom teachers and showcase pedagogical strategies with digital technologies. There is a dearth of research on digital…

  4. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

    DOE PAGES

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; ...

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffinemore » tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.« less

  5. High temperature Oxidation of ODS alloy with zirconia dispersions synthesized using Arc Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Bandriyana; Sujatno, A.; Salam, R.; Sugeng, B.; Dimyati, A.

    2017-02-01

    Microstructure formation and oxidation behaviour of the Oxide Dispersion Strengthened (ODS) steels for application as structure material in Nuclear Power Plant was investigated. A mixture composed of Fe and 12 wt. % Cr powder with addition of 0.5 and 1 wt.% ZrO2 particles was milled and isostatic pressed to form a sample coin. The coin was then consolidated in the Arc Plasma Sintering (APS) for 4 minutes. The samples were subjected to the high temperature oxidation test in the Magnetic Suspension Balance (MSB). The oxidation test was carried out at 700°C for 6 hours to evaluate the oxide growth in the early stage of it formation by extraction the mass gain curve. The Scanning Electron Microscope (SEM) imaging and X-ray Diffraction Spectroscopy (EDX) elemental mapping were performed to study the microstructure change and compositional distribution. SEM and EDX observation revealed the time dependent development of the Fe-Cr-phases during consolidation. The oxidation rate behaviour of the samples followed the parabolic rate characteristic for inward oxidation process driven by oxygen inward diffusion through the oxide scale with the maximum weight gain around of 60 g/m2. The oxidation resistance was strongly affected by the formation of the oxide protective layer on the surface. In so far, addition of zirconia particles has played no significant role to the oxidation behaviour.

  6. Haemocompatibility of iron oxide nanoparticles synthesized for theranostic applications: a high-sensitivity microfluidic tool

    NASA Astrophysics Data System (ADS)

    Rodrigues, Raquel O.; Bañobre-López, Manuel; Gallo, Juan; Tavares, Pedro B.; Silva, Adrián M. T.; Lima, Rui; Gomes, Helder T.

    2016-07-01

    The poor heating efficiency of the most reported magnetic nanoparticles (MNPs), allied to the lack of comprehensive biocompatibility and haemodynamic studies, hampers the spread of multifunctional nanoparticles as the next generation of therapeutic bio-agents in medicine. The present work reports the synthesis and characterization, with special focus on biological/toxicological compatibility, of superparamagnetic nanoparticles with diameter around 18 nm, suitable for theranostic applications (i.e. simultaneous diagnosis and therapy of cancer). Envisioning more insights into the complex nanoparticle-red blood cells (RBCs) membrane interaction, the deformability of the human RBCs in contact with magnetic nanoparticles (MNPs) was assessed for the first time with a microfluidic extensional approach, and used as an indicator of haematological disorders in comparison with a conventional haematological test, i.e. the haemolysis analysis. Microfluidic results highlight the potential of this microfluidic tool over traditional haemolysis analysis, by detecting small increments in the rigidity of the blood cells, when traditional haemotoxicology analysis showed no significant alteration (haemolysis rates lower than 2 %). The detected rigidity has been predicted to be due to the wrapping of small MNPs by the bilayer membrane of the RBCs, which is directly related to MNPs size, shape and composition. The proposed microfluidic tool adds a new dimension into the field of nanomedicine, allowing to be applied as a high-sensitivity technique capable of bringing a better understanding of the biological impact of nanoparticles developed for clinical applications.

  7. Facilely synthesized porous NiCo2O4 flowerlike nanostructure for high-rate supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Haichao; Jiang, Jianjun; Zhang, Li; Qi, Tong; Xia, Dandan; Wan, Houzhao

    2014-02-01

    We have developed a facile and scalable method to grow porous NiCo2O4 nanostructure. The conductivity is measured by a linear sweep voltammetry, which indicates that the conductivity of the NiCo2O4 sample is at least two orders of magnitude higher than those of NiO and Co3O4 samples. The conductive NiCo2O4 hybrid electrode delivers an enhanced specific capacitance of 658 F g-1 at 1 A g-1 compared to NiO and Co3O4. Excellent rate capability, 78% specific capacitance retention for a 20-time current density increase and 77% specific capacitance retention for a 50-time scan rate rise, is achieved. The NiCo2O4 sample demonstrates ultralong cycling lifespan, no observable degradation is found for the total cycle numbers as high as 10000 cycles. Furthermore, the excellent capacitive performance of porous NiCo2O4 electrode is also evaluated by a two-electrode asymmetric supercapacitor device. The asymmetric supercapacitor device delivers a 64% rate property for the current density increase 20 times. Remarkably, the asymmetric supercapacitor device also shows ultrahigh long-term stability, 93.5% of specific capacitance can still be retained after 10,000 cycles cycling. These excellent capacitive performances indicate the as-fabricated porous NiCo2O4 flowerlike nanostructure a promising electrode materials for supercapacitors.

  8. High-frequency properties of oil-phase-synthesized ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Ding, Hao-Feng; Yang, Hai-Tao; Liu, Li-Ping; Ren, Xiao; Song, Ning-Ning; Shen, Jun; Zhang, Xiang-Qun; Cheng, Zhao-Hua; Zhao, Guo-Ping

    2015-02-01

    Monodispersive ZnO nanoparticles each with a hexagonal wurtzite structure are facilely prepared by the high-temperature organic phase method. The UV-visible absorption peak of ZnO nanoparticles presents an obvious blue-shift from 385 nm of bulk ZnO to 369 nm. Both the real part and the image part of the complex permittivity of ZnO nanoparticles from 0.1 GHz to 10 GHz linearly decrease without obvious resonance peak appearing. The real parts of intrinsic permittivity of ZnO nanoparticles are about 5.7 and 5.0 at 0.1 GHz and 10 GHz respectively, and show an obvious size-dependent behavior. The dielectric loss angle tangent (tanδ) of ZnO nanoparticles with a different weight ratio shows a different decreasing law with the increase of frequency. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274370 and 51471185) and the National Basic Research Program of China (Grant Nos. 2012CB933102 and 2011CB921801).

  9. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

    SciTech Connect

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; Steren, Carlos A.; Goodwin, Andrew; Coughlin, E. Bryan; Gido, Samuel; Beiner, Mario; Hong, Kunlun; Kang, Nam -Goo; Mays, Jimmy; Wang, Weiyu; White, Benjamin T.

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffine tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.

  10. Structural and magnetic properties of DyMn(2)D(6) synthesized under high deuterium pressure.

    PubMed

    Paul-Boncour, V; Filipek, S M; Wierzbicki, R; André, G; Bourée, F; Guillot, M

    2009-01-07

    DyMn(2)D(6) has been prepared by applying high gaseous deuterium pressure on DyMn(2). This phase is isostructural with other RMn(2)D(6) (R = Y, Er) compounds and crystallizes with a K(2)PtCl(6) type structure having an ordered anion and a partially disordered cation arrangement because Dy and half the Mn atoms are randomly substituted in the same 8c site. The reverse susceptibility follows a Curie-Weiss law with an effective moment of 10 μ(B) similar to that of DyMn(2). Short range magnetic order, corresponding to ferromagnetic correlations, is observed in the neutron patterns up to 10 K and can be attributed to Dy-Dy interactions. The decomposition of the deuteride into Mn and DyD(2), studied by thermal gravimetric analysis, occurs between 470 and 650 K. A further deuterium desorption takes place above 920 K.

  11. 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.

  12. 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.

  13. Highly magnetic Fe2O3 nanoparticles synthesized by laser pyrolysis used for biological and heat transfer applications

    NASA Astrophysics Data System (ADS)

    Dumitrache, F.; Morjan, I.; Fleaca, C.; Badoi, A.; Manda, G.; Pop, S.; Marta, D. S.; Huminic, G.; Huminic, A.; Vekas, L.; Daia, C.; Marinica, O.; Luculescu, C.; Niculescu, A.-M.

    2015-05-01

    γFe2O3-based nanoparticles were synthesized by laser pyrolysis using various optimized Fe(CO)5, O2 and C2H4 flow ratios in the reactive mixture, and different laser power values. Depending on particular conditions, two different iron oxide-based nanoparticles (MNPs) were synthesized, with a hydrophilic or hydrophobic behavior, both presenting a high magnetization saturation (around 70 emu/g). TEM, EDX, XRD and magnetic analyses were performed for a comprehensive characterization. The raw powders were successfully dispersed in aqueous media using L-DOPA as stabilizing agent. Dispersed samples, with or without stabilization agents, have been tested and DLS measurements proved their good stability, with the hydrodynamic diameter varying between 70 and 150 nm when the stabilizing agent was used. Thermal conductivity and viscosity tests on L-DOPA-functionalized MNPs suspensions reveal the increasing (up to 40%) of their thermal conductivity, accompanied by a viscosity increase of only 5%, validating them as thermal transfer fluids. Water-based nanoparticle dispersions and also those stabilized with L-DOPA proved a good biocompatibility, as demonstrated by a preliminary in vitro study on mouse primary leukocytes and human breast carcinoma cell line MCF-7; although ingested by the investigated cells, MNPs do not decrease cellular viability and proliferation.

  14. Photodimerization in dipeptides for high capacity optical digital storage

    SciTech Connect

    Ramanujam, P.S.; Berg, Rolf H.

    2004-09-06

    We have developed peptide materials with chromophores that undergo cycloaddition, suitable for terabit optical digital storage in a 5.25 in. disc. The rationale behind this design is that the length and rigidity of the backbone can be adjusted to facilitate the formation of a photodimer without large physical movements of the chromophores on exposure to UV light. Initially strongly absorbing films transmit up to 50% of light on irradiation at dimerizing wavelengths. This property can be utilized to record grey levels. An intensity-dependent transmission behavior has been observed that may enable data to be written and read at the same wavelength.

  15. Modelling high arctic percent vegetation cover using field digital images and high resolution satellite data

    NASA Astrophysics Data System (ADS)

    Liu, Nanfeng; Treitz, Paul

    2016-10-01

    In this study, digital images collected at a study site in the Canadian High Arctic were processed and classified to examine the spatial-temporal patterns of percent vegetation cover (PVC). To obtain the PVC of different plant functional groups (i.e., forbs, graminoids/sedges and mosses), field near infrared-green-blue (NGB) digital images were classified using an object-based image analysis (OBIA) approach. The PVC analyses comparing different vegetation types confirmed: (i) the polar semi-desert exhibited the lowest PVC with a large proportion of bare soil/rock cover; (ii) the mesic tundra cover consisted of approximately 60% mosses; and (iii) the wet sedge consisted almost exclusively of graminoids and sedges. As expected, the PVC and green normalized difference vegetation index (GNDVI; (RNIR - RGreen)/(RNIR + RGreen)), derived from field NGB digital images, increased during the summer growing season for each vegetation type: i.e., ∼5% (0.01) for polar semi-desert; ∼10% (0.04) for mesic tundra; and ∼12% (0.03) for wet sedge respectively. PVC derived from field images was found to be strongly correlated with WorldView-2 derived normalized difference spectral indices (NDSI; (Rx - Ry)/(Rx + Ry)), where Rx is the reflectance of the red edge (724.1 nm) or near infrared (832.9 nm and 949.3 nm) bands; Ry is the reflectance of the yellow (607.7 nm) or red (658.8 nm) bands with R2's ranging from 0.74 to 0.81. NDSIs that incorporated the yellow band (607.7 nm) performed slightly better than the NDSIs without, indicating that this band may be more useful for investigating Arctic vegetation that often includes large proportions of senescent vegetation throughout the growing season.

  16. The implementation of high speed digital PSD in optically pumping magnetometers

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Cheng, Defu; Zhou, Zhijian; Ma, Ming; Wang, Chao; Hu, Ruifan

    2017-01-01

    The 4He optically pumping magnetometer is a kind of high resolution instrument for measuring magnetic field intensity. Its response speed cannot meet the requirements in some experiments. By analyzing many factors, Phase Sensitive Detector (PSD) which is the key part of the lock-in amplifier processes data at a very slow speed is found. To improve its performance, this paper introduces a parallel digital phase sensitive detector based on coordinate rotation digital computer (CORDIC) algorithm. The cost time of the parallel digital phase sensitive detector is only 5.1% of the previous one. It can greatly enhance the response speed of the 4He optically pumping magnetometer.

  17. High precision (14 bit), high density (octal) analog to digital converter for spectroscopy applications

    NASA Astrophysics Data System (ADS)

    Subramaniam, E. T.; Jain, Mamta; Bhowmik, R. K.; Tripon, Michel

    2008-10-01

    Nuclear and particle physics experiments with large number of detectors require signal processing and data collection strategies that call for the ability to collect large amount of data while not sacrificing the precision and accuracy of the data being collected. This paper deals with the development of a high precision pulse peak detection, analog to digital converter (ADC) module with eight independent channels in plug-in daughter card motherboard model, best suited for spectroscopy experiments. This module provides multiple channels without cross-talk and of 14 bit resolution, while maintaining high density (each daughter card has an area of just 4.2″×0.51″) and exhibiting excellent integral nonlinearity (≤±2 mV or ±0.02% full scale reading) and differential nonlinearity (≤±1%). It was designed, developed and tested, in house, and gives added advantages of cost effectiveness and ease of maintenance.

  18. High precision (14 bit), high density (octal) analog to digital converter for spectroscopy applications.

    PubMed

    Subramaniam, E T; Jain, Mamta; Bhowmik, R K; Tripon, Michel

    2008-10-01

    Nuclear and particle physics experiments with large number of detectors require signal processing and data collection strategies that call for the ability to collect large amount of data while not sacrificing the precision and accuracy of the data being collected. This paper deals with the development of a high precision pulse peak detection, analog to digital converter (ADC) module with eight independent channels in plug-in daughter card motherboard model, best suited for spectroscopy experiments. This module provides multiple channels without cross-talk and of 14 bit resolution, while maintaining high density (each daughter card has an area of just 4.2(")x0.51(")) and exhibiting excellent integral nonlinearity (< or = +/-2 mV or +/-0.02% full scale reading) and differential nonlinearity (< or = +/-1%). It was designed, developed and tested, in house, and gives added advantages of cost effectiveness and ease of maintenance.

  19. Purification of Al(OH)3 synthesized by Bayer process for preparation of high purity alumina as sapphire raw material

    NASA Astrophysics Data System (ADS)

    Park, No-Kuk; Choi, Hee-Young; Kim, Do-Hyeong; Lee, Tae Jin; Kang, Misook; Lee, Won Gun; Kim, Heun Duk; Park, Joon Woo

    2013-06-01

    To produce high purity alumina as the raw material for sapphire growth, gibbsite, which is the precursor for the synthesis of alumina, was synthesized by the Bayer process, and treated with an acid solution to remove the sodium component. In this study, the digestion process was carried out under the following conditions: an Al/Na ratio of 0.9 with a 5 N NaOH solution and a temperature of 140 °C. Bauxite containing 75 wt% alumina was converted to a sodium aluminate solution, and 60 wt% of the dissolved aluminate was crystallized to gibbsite. The sodium content in the gibbsite, which was measured by inductively coupled plasma/optical emission spectroscopy, was reduced by approximately 5700 ppm and below 2900 ppm after the water washing and acid treatments, respectively. The sodium content decreased with increasing acid concentration in the solution, temperature and acid treatment time.

  20. Highly Active Supported Pt Nanocatalysts Synthesized by Alcohol Reduction towards Hydrogenation of Cinnamaldehyde: Synergy of Metal Valence and Hydroxyl Groups.

    PubMed

    Wang, Yanyan; He, Wanhong; Wang, Liren; Yang, Junjiao; Xiang, Xu; Zhang, Bing; Li, Feng

    2015-07-01

    The hydrogenation of α,β-unsaturated aldehydes to allylic alcohols or saturated aldehydes provides a typical example to study the catalytic effect on structure-sensitive reactions. In this work, supported platinum nanocatalysts over hydrotalcite were synthesized by an alcohol reduction method. The Pt catalyst prepared by the reduction with a polyol (ethylene glycol) outperforms those prepared with ethanol and methanol in the hydrogenation of cinnamaldehyde. The selectivity towards the C=O bond is the highest over the former, although its mean size of Pt particles is the smallest. The hydroxyl groups on hydrotalcite could act as an internally accessible promoter to enhance the selectivity towards the C=O bond. The optimal Pt catalyst showed a high activity with an initial turnover frequency (TOF) of 2.314 s(-1). This work unveils the synergic effect of metal valence and in situ promoter on the chemoselective hydrogenation, which could open up a new direction in designing hydrogenation catalysts.

  1. Route to optimal generation of soft X-ray high harmonics with synthesized two-color laser pulses

    PubMed Central

    Jin, Cheng; Wang, Guoli; Le, Anh-Thu; Lin, C. D.

    2014-01-01

    High harmonics extending to X-rays have been generated from gases by intense lasers. To establish these coherent broadband radiations as an all-purpose tabletop light source for general applications in science and technology, new methods are needed to overcome the present low conversion efficiencies. Here we show that the conversion efficiency may be drastically increased with an optimized two-color pulse. By employing an optimally synthesized 2-µm mid-infrared laser and a small amount of its third harmonic, we show that harmonic yields from sub- to few-keV energy can be increased typically by ten-fold over the optimized single-color one. By combining with favorable phase-matching and together with the emerging high-repetition MHz mid-infrared lasers, we anticipate efficiency of harmonic yields can be increased by four to five orders in the near future, thus paving the way for employing high harmonics as useful broadband tabletop light sources from the extreme ultraviolet to the X-rays, as well as providing new tools for interrogating ultrafast dynamics of matter at attosecond timescales. PMID:25400015

  2. AC losses in high pressure synthesized MgB2 bulk rings measured by a transformer method

    NASA Astrophysics Data System (ADS)

    Meerovich, V.; Sokolovsky, V.; Prikhna, T.; Gawalek, W.; Habisreuther, T.

    2013-03-01

    Recently developed manufacturing technologies use high pressure and various doping additions to prepare bulk MgB2-based materials with a high critical current density measured by the magnetization method. We use a contactless transformer method, which is based on studying the superconductor response to an induced transport current, to measure AC losses in bulk MgB2 rings synthesized under high pressure. The obtained dependence of the losses on the primary current (applied magnetic field) is fitted by a power law with an exponent of ˜2.1 instead of the cubic dependence predicted by Bean’s model and power law electric field-current density (E-J) characteristics with a large exponent. An unusually strong dependence of the AC losses on the frequency is also observed. It is shown that the E-J characteristic of bulk MgB2 is well fitted by the dependence used in the extended critical state model based on account of the viscous vortex motion in the flux flow regime. Numerical simulation using this E-J characteristic gives current and frequency AC loss dependences that agree well with the experimental results.

  3. Induction of Silencing in Plants by High-Pressure Spraying of In vitro-Synthesized Small RNAs

    PubMed Central

    Dalakouras, Athanasios; Wassenegger, Michèle; McMillan, John N.; Cardoza, Vinitha; Maegele, Ira; Dadami, Elena; Runne, Miriam; Krczal, Gabi; Wassenegger, Michael

    2016-01-01

    In this report, we describe a method for the delivery of small interfering RNAs (siRNAs) into plant cells. In vitro synthesized siRNAs that were designed to target the coding region of a GREEN FLUORESCENT PROTEIN (GFP) transgene were applied by various methods onto GFP-expressing transgenic Nicotiana benthamiana plants to trigger RNA silencing. In contrast to mere siRNA applications, including spraying, syringe injection, and infiltration of siRNAs that all failed to induce RNA silencing, high pressure spraying of siRNAs resulted in efficient local and systemic silencing of the GFP transgene, with comparable efficiency as was achieved with biolistic siRNA introduction. High-pressure spraying of siRNAs with sizes of 21, 22, and 24 nucleotides (nt) led to local GFP silencing. Small RNA deep sequencing revealed that no shearing of siRNAs was detectable by high-pressure spraying. Systemic silencing was basically detected upon spraying of 22 nt siRNAs. Local and systemic silencing developed faster and more extensively upon targeting the apical meristem than spraying of mature leaves. PMID:27625678

  4. Synthesizing Chaos

    NASA Astrophysics Data System (ADS)

    Blakely, Jonathan; Corron, Ned; Hayes, Scott; Pethel, Shawn

    2007-03-01

    Chaos is usually attributed only to nonlinear systems. Yet it was recently shown that chaotic waveforms can be synthesized by linear superposition of randomly polarized basis functions. The basis function contains a growing oscillation that terminates in a large pulse. We show that this function is easily realized when viewed backward in time as a pulse followed by ringing decay. Consequently, a linear filter driven by random pulses outputs a waveform that, when viewed backward in time, exhibits essential qualities of chaos, i.e. determinism and a positive Lyapunov exponent. This phenomenon suggests that chaos may be connected to physical theories whose framework is not that of a deterministic dynamical system. We demonstrate that synthesizing chaos requires a balance between the topological entropy of the random source and the dissipation in the filter. Surprisingly, using different encodings of the random source, the same filter can produce both Lorenz-like and R"ossler-like waveforms. The different encodings can be viewed as grammar restrictions on a more general encoding that produces a chaotic superset encompassing the Lorenz and R"ossler paradigms of nonlinear dynamics. Thus, the language of deterministic chaos provides a useful description for a class of signals not generated by a deterministic system.

  5. Realizing the increased potential of an open-system high-definition digital projector design

    NASA Astrophysics Data System (ADS)

    Daniels, Reginald

    1999-05-01

    Modern video projectors are becoming more compact and capable. Various display technologies are very competitive and are delivering higher performance and more compact projectors to market at an ever quickening pace. However the end users are often left with the daunting task of integrating the 'off the self projectors' into a previously existing system. As the projectors become more digitally enhanced, there will be a series of designs, and the digital projector technology matures. The design solutions will be restricted by the state of the art at the time of manufacturing. In order to allow the most growth and performance for a given price, many design decisions will be made and revisited over a period of years or decades. A modular open digital system design concept is indeed a major challenge of the future high definition digital displays for al applications.

  6. 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

  7. High-speed 3D imaging by parallel phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Awatsuji, Yasuhiro; Xia, Peng; Matoba, Osamu

    2015-07-01

    As a high-speed three-dimensional (3D) imaging technique, parallel phase-shifting digital holography is presented. This technique records a single hologram of an object with an image sensor having a phase-shift array device and reconstructs the instantaneous 3D image of the object with a computer. In this technique, a single hologram in which the multiple holograms required for phase-shifting digital holography are multiplexed by using space-division multiplexing technique pixel by pixel. Also, we present a high-speed parallel phase-shifting digital holography system. The system consists of an interferometer, a continuous-wave laser, and a high-speed polarization imaging camera. Motion pictures of dynamic phenomena at the rate of up to 1,000,000 frames per second have been achieved by the high-speed system.

  8. Advanced High-Speed 16-Bit Digitizer System

    SciTech Connect

    2012-05-01

    The fastest commercially available 16-bit ADC can only perform around 200 mega-samples per second (200 MS/s). Connecting ADC chips together in eight different time domains increases the quantity of samples taken by a factor of eight. This method of interleaving requires that the input signal being sampled is split into eight identical signals and arrives at each ADC chip at the same point in time. The splitting of the input signal is performed in the analog front end containing a wideband filter that impedance matches the input signal to the ADC chips. Each ADC uses a clock to tell it when to perform a conversion. Using eight unique clocks spaced in 45-degree increments is the method used to time shift when each ADC chip performs its conversion. Given that this control clock is a fixed frequency, the clock phase shifting is accomplished by tightly controlling the distance that the clock must travel, resulting in a time delay. The interleaved ADC chips will now generate digital data in eight different time domains. These data are processed inside a field-programmable gate array (FPGA) to move the data back into a single time domain and store it into memory. The FPGA also contains a Nios II processor that provides system control and data retrieval via Ethernet.

  9. New investigations on shock-wave synthesized high-pressure phases in the system Si-Al-O-N

    NASA Astrophysics Data System (ADS)

    Schlothauer, T.; Greif, A.; Keller, K.; Schwarz, M. R.; Kroke, E.; Heide, G.

    2012-12-01

    The shock-wave synthesis of nanostructured high-pressure phases at a gram-scale permits the analysis of spinel type nitrides with different chemical composition using methods not suitable for microgram amounts of material. Methods with a significant mass loss through the analytical process like TG-MS or FT-IR or bulk methods at the g-scale like 29Si-MAS-NMR or neutron diffraction were used. The synthesis of pure high-pressure modifications (gamma-phases) of different SiAlON-compounds using amorphous H-bearing precursors at pressures of 30-40 GPa is a necessary prerequisite for precise determinations of crystal chemical features. Etching with HF is a well-known method to purify the high-pressure nitrides (Sekine 2002). The etched parts were analyzed by neutron diffraction, TG-MS, and carrier gas hot extraction (CGHE). Volatile elements like H2 and Cl2, as well as non-stoichiometric oxygen and nitrogen, and NOx, H2O are enriched in the disordered rims. This degassing process ends at temperatures of approximately 600°C, while the spinel structure remains well preserved up to 1300°C. Under these conditions the gamma-phases stay unchanged under air, argon and vacuum. Furthermore chlorine, an important impurity of the H-bearing precursors neither influences the synthesized products nor the synthesis process itself. IR-spectroscopy of gamma-Si3(O,N)4 shows that peak shifts of octahedral lattice vibrations (≈ 680 cm-1) and both tetrahedral vibrations (ny3 and ny4) (Jeanloz 1980, Preudhomme & Tarte 1971) to higher frequencies with decreasing oxygen content occur. This effect is also visible in samples contaminated with impurities of low pressure modifications. The more complex structure of gamma-SiAlON and the simultaneously exchange of the cation- and the anion-positions prevents the appearance of this important feature. Yet to be synthesized pure gamma-SiAlON using similar H-bearing precursors is necessary to resolve its structure. Sekine, T., H. He, T. Kobayashi, K

  10. Spark plasma sintered Sm(2)Co(17)-FeCo nanocomposite permanent magnets synthesized by high energy ball milling.

    PubMed

    Sreenivasulu, G; Gopalan, R; Chandrasekaran, V; Markandeyulu, G; Suresh, K G; Murty, B S

    2008-08-20

    Nanocomposite Sm(2)Co(17)-5 wt% FeCo magnets were synthesized by high energy ball milling followed by consolidation into bulk shape by the spark plasma sintering technique. The evolution of magnetic properties was systematically investigated in milled powders as well as in spark plasma sintered samples. A high energy product of 10.2 MGOe and the other magnetic properties of M(s) = 107 emu g(-1), M(r) = 59 emu g(-1), M(r)/M(s) = 0.55 and H(c) = 6.4 kOe were achieved in a 5 h milled and spark plasma sintered Sm(2)Co(17)-5 wt% FeCo nanocomposite magnet. The spark plasma sintering was carried out at 700 °C for 5 min with a pressure of 70 MPa. The nanocomposite showed a higher Curie temperature of 955 °C for the Sm(2)Co(17) phase in comparison to its bulk Curie temperature for the Sm(2)Co(17) phase (920 °C). This higher Curie temperature can improve the performance of the magnet at higher temperatures.

  11. Crystallization Behavior of Perovskite in the Synthesized High-Titanium-Bearing Blast Furnace Slag Using Confocal Scanning Laser Microscope

    NASA Astrophysics Data System (ADS)

    Hu, Meilong; Liu, Lu; Lv, Xuewei; Bai, Chenguang; Zhang, Shengfu

    2013-10-01

    The isothermal phase composition of high-titanium-bearing slag (23 mass pct TiO2) under an argon atmosphere during cooling process from 1723 K (1450 °C) was calculated by FactSage.6.3 (CRCT-ThermFact Inc., Montréal, Canada). Three main phases, which were perovskite, titania spinel, and clinopyroxene, could form during the cooling process and they precipitated at 1713 K, 1603 K, and 1498 K (1440 °C, 1330 °C, and 1225 °C), respectively. The nonisothermal crystallization process of perovskite in synthesized high-titanium-bearing slag was studied in situ by a confocal scanning laser microscope (CSLM) with cooling rate of 30 K/min. The results showed that the primary phase was perovskite that precipitated at 1703 K (1430 °C). The whole precipitation and growth process of perovskite was obtained, whereas other phases formed as glass under the current experimental conditions. Perovskite grew along a specific growth track and finally appeared with snowflake morphology. The growing kinetics of perovskite formation from molten slag were also mentioned.

  12. Whole ceramic-like microreactors from inorganic polymers for high temperature or/and high pressure chemical syntheses.

    PubMed

    Ren, Wurong; Perumal, Jayakumar; Wang, Jun; Wang, Hao; Sharma, Siddharth; Kim, Dong-Pyo

    2014-02-21

    Two types of whole ceramic-like microreactors were fabricated from inorganic polymers, polysilsesquioxane (POSS) and polyvinylsilazane (PVSZ), that were embedded with either perfluoroalkoxy (PFA) tube or polystyrene (PS) film templates, and subsequently the templates were removed by physical removal (PFA tube) or thermal decomposition (PS). A POSS derived ceramic-like microreactor with a 10 cm long serpentine channel was obtained by an additional "selective blocking of microchannel" step and subsequent annealing at 300 °C for 1 h, while a PVSZ derived ceramic-like microreactor with a 14 cm long channel was yielded by a co-firing process of the PVSZ-PS composite at 500 °C for 2 h that led to complete decomposition of the film template leaving a microchannel behind. The obtained whole ceramic-like microfluidic devices revealed excellent chemical and thermal stabilities in various solvents, and they were able to demonstrate unique chemical performance at high temperature or/and high pressure conditions such as Michaelis-Arbuzov rearrangement at 150-170 °C, Wolff-Kishner reduction at 200 °C, synthesis of super-paramagnetic Fe3O4 nanoparticles at 320 °C and isomerisation of allyloxybenzene to 2-allylphenol (250 °C and 400 psi). These economic ceramic-like microreactors fabricated by a facile non-lithographic method displayed excellent utility under challenging conditions that is superior to any plastic microreactors and comparable to glass and metal microreactors with high cost.

  13. Characterizing Vibratory Kinematics in Children and Adults with High-Speed Digital Imaging

    ERIC Educational Resources Information Center

    Patel, Rita; Dubrovskiy, Denis; Döllinger, Michael

    2014-01-01

    Purpose: The aim of this study is to quantify and identify characteristic vibratory motion in typically developing prepubertal children and young adults using high-speed digital imaging. Method: The vibrations of the vocal folds were recorded from 27 children (ages 5-9 years) and 35 adults (ages 21-45 years), with high speed at 4,000 frames per…

  14. Structure and physical properties of nanoclustered graphene synthesized from C60 fullerene under high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Chernogorova, Olga; Potapova, Iraida; Drozdova, Ekaterina; Sirotinkin, Vladimir; Soldatov, Alexander V.; Vasiliev, Alexander; Ekimov, Evgeny

    2014-01-01

    C60 treatment at 5-8 GPa, ˜1000 °C results in the fullerene cage collapse and transformation to a phase with outstanding mechanical properties. A detailed structural analysis of the phase reveals that it comprised 7-12 layer graphene clusters with lateral dimension of 2-4 nm. Raman spectra of the nanoclustered graphene phase are similar to those of disordered sp2 carbon structure with an admixture of sp3-bonded carbon. The phase is characterized by a high (up to 19 GPa) hardness, relatively low (about 70 GPa) Young modulus and up to 95% elastic recovery, determining excellent wear resistance and good antifriction properties.

  15. High-Speed, High-Resolution Time-to-Digital Conversion

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor; Garcia, Rafael

    2013-01-01

    This innovation is a series of time-tag pulses from a photomultiplier tube, featuring short time interval between pulses (e.g., 2.5 ns). Using the previous art, dead time between pulses is too long, or too much hardware is required, including a very-high-speed demultiplexer. A faster method is needed. The goal of this work is to provide circuits to time-tag pulses that arrive at a high rate using the hardwired logic in an FPGA - specifically the carry chain - to create what is (in effect) an analog delay line. High-speed pulses travel down the chain in a "wave." For instance, a pulse train has been demonstrated from a 1- GHz source reliably traveling down the carry chain. The size of the carry chain is over 10 ns in the time domain. Thus, multiple pulses will travel down the carry chain in a wave simultaneously. A register clocked by a low-skew clock takes a "snapshot" of the wave. Relatively simple logic can extract the pulses from the snapshot picture by detecting the transitions between logic states. The propagation delay of CMOS (complementary metal oxide semiconductor) logic circuits will differ and/or change as a result of temperature, voltage, age, radiation, and manufacturing variances. The time-to-digital conversion circuits can be calibrated with test signals, or the changes can be nulled by a separate on-die calibration channel, in a closed loop circuit.

  16. Low-cost digital visualization and high-speed tracking of supersonic shockwaves

    NASA Astrophysics Data System (ADS)

    Bryanston-Cross, Peter J.; Skeen, Andrew J.; Timmerman, Brenda H.; Dunkley, P.; Paduano, James D.; Guenette, G. R., Jr.

    2003-11-01

    A low-cost and low-maintenance digital focused shadowgraph flow visualization system has been developed to provide fast diagnostics of rapidly changing phenomena in supersonic flows. The system is particularly designed for tracking shock positions in a supersonic inlet, enabling high-speed active shock control. It is based on a low-cost, high-intensity white LED light source, which can be flashed with microsecond pulses enabling freeze-frame imaging of constant illumination quality. The system features three modes of operation: (1) High-resolution digital still frames and sequences (1280 x 1024, 2fps), (2) High-resolution digital frames and sequences showing spatial-temporal variation in flow field (1280 x 1024, 12 fps), (3) Adjustable windowed digital frames at reduced resolution, but at high frame rates (980 fps at 1280 x 8 pixel viewing area). The three modes of operation allow high-speed tracking of flow features such as moving of shock waves (up to 980 Hz) as well as overall instantaneous views of the flow. Furthermore, it allows direct identification of areas where high-speed changes occur. The positional shock data can be transmitted directly to a shock-stabilizing control system. Results are presented of the unsteady flow generated by an aspirated cone-shaped nozzle in a supersonic flow in the supersonic wind tunnel of the MIT Gas Turbine Laboratory.

  17. High-speed phase imaging by parallel phase-shifting digital holography.

    PubMed

    Kakue, Takashi; Yonesaka, Ryosuke; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-11-01

    Parallel phase-shifting digital holography can obtain three-dimensional information of a dynamically moving object with high accuracy by using space-division multiplexing of multiple holograms required for phase-shifting interferometry. We demonstrated high-speed parallel phase-shifting digital holography and obtained images of the phase variation of air caused by a compressed gas flow sprayed from a nozzle. In particular, we found the interesting phenomenon of periodic phase distributions. Reconstructed images were obtained at frame rates of 20,000 and 180,000 frames per second.

  18. A facile approach for synthesizing Fe-based layered double hydroxides with high purity and its exfoliation.

    PubMed

    Wang, Yinling; Li, Fajun; Dong, Shengye; Liu, Xiaowang; Li, Maoguo

    2016-04-01

    Transition metal (e.g., Fe, Co, Ni)-based layered double hydroxides (LDHs) and their exfoliated nanosheets have great potential applications due to their redox and magnetic properties. Here we report a facile approach for the preparation of Co-Fe LDHs with good crystallinity and high purity. The proposed approach includes two steps: (1) The mixed divalent metal (e.g., Co(2+), Fe(2+)) hydroxides were first synthesized using a homogeneous precipitation without piping N2 into the system; hexamethylenetetramine (HMT) was the hydrolysis agent providing OH(-), and hydroxylamine hydrochloride (HAH) was used as both a reducing and a complexing reagent. (2) Then the as-prepared hydroxides were slowly oxidated by air and simultaneously intercalated by CO3(2-) to form CO3-intercalated LDHs. The Co-Fe LDHs were roundly characterized by XRD, SEM, EDX and FT-IR. The effect of HAH on the morphology and structure of the Co-Fe LDHs was also studied. The magnetism of Co-Fe LDHs at room temperature was investigated and the results showed that the LDHs displayed a low saturation magnetization value of 6.3emug(-1), suggesting that the purity of the products was very high. In addition, the intercalated CO3(2-) in the Co-Fe LDHs could be successfully exchanged with other anions such as Cl(-) and ClO4(-). Furthermore, the exchanged-LDHs could be exfoliated in formamide. This work establishes a new method for the synthesis of Fe-based LDHs with good crystallinity and high purity under mild conditions, and can accelerate the development of applications using these layered materials.

  19. High stable suspension of magnetite nanoparticles in ethanol by using sono-synthesized nanomagnetite in polyol medium

    SciTech Connect

    Bastami, Tahereh Rohani; Entezari, Mohammad H.

    2013-09-01

    Graphical abstract: - Highlights: • The sonochemical synthesis of magnetite nanoparticles was carried out in EG without any surfactant. • The nanoparticles with sizes ∼24 nm were composed of small building blocks with sizes ∼2 nm. • The hydrophilic magnetite nanoparticles were stable in ethanol even after 8 months. • Ultrasonic intensity showed a crucial role on the obtained high stable magnetite nanoparticles in ethanol. - Abstract: The sonochemical synthesis of magnetite nanoparticles was carried out at relatively low temperature (80 °C) in ethylene glycol (EG) as a polyol solvent. The particle size was determined by transmission electron microscopy (TEM). The magnetite nanoparticles with an average size of 24 nm were composed of small building blocks with an average size of 2–3 nm and the particles exhibited nearly spherical shape. The surface characterization was investigated by using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The stability of magnetite nanoparticles was studied in ethanol as a polar solvent. The nanoparticles showed an enhanced stability in ethanol which is due to the hydrophilic surface of the particles. The colloidal stability of magnetite nanoparticles in ethanol was monitored by UV–visible spectrophotometer. According to the results, the nanoparticles synthesized in 30 min of sonication with intensity of 35 W/cm{sup 2} (50%) led to a maximum stability in ethanol as a polar solvent with respect to the other applied intensities. The obtained magnetite nanoparticles were stable for more than12 months.

  20. Application of high-performance liquid chromatographic methodology to the analysis of hemoglobins synthesized in erythroid progenitor cells.

    PubMed

    Bhaumik, K; Huisman, T H

    1989-11-10

    High-performance liquid chromatography (HPLC) has been successfully used in the quantitation of the relatively minute amounts of hemoglobin types recovered from in vitro cultures of hemoglobin-synthesizing erythroid progenitor (BFU-E) cells. This reversed-phase HPLC method uses the Vydac C4 column and water-acetonitrile-trifluoroacetic acid as mobile phases; it has been applied to the study of fetal hemoglobin synthesis patterns in ten homozygous sickle cell anemia patients and a similar number of their heterozygous relatives along with a few normal control subjects. A significant increase in the total gamma chain level was observed in the BFU-E lysate samples corresponding to the whole blood lysates of all the patients and their heterozygous relatives, except in one patient with the beta S haplotype Mor. On the other hand, the relative level of the G gamma chains appeared to be decreased in the BFU-E lysate samples of all except the individuals carrying the Mor haplotype, where it is reversed. The method has considerable advantages over other chromatographic and electrophoretic procedures; it is extremely sensitive and allows quantitation of all different globin chains in one single chromatogram.

  1. Intermittent microwave heating synthesized high performance spherical LiFePO{sub 4}/C for Li-ion batteries

    SciTech Connect

    Zou, Hongli; Zhang, Guanghui; Shen, Pei Kang

    2010-02-15

    An intermittent microwave heating method was used to synthesize spherical LiFePO{sub 4}/C in the presence of glucose as reductive agent and carbon source without the use of the inert gas in the oven processes. The FePO{sub 4} was used as iron precursor to reduce the cost and three lithium salts of Li{sub 2}CO{sub 3}, LiOH and CH{sub 3}COOLi were chosen for comparison of the resulting materials. The materials can be alternatively heated by this method at a temperature controllable mode for crystallization and phase transformation and to provide relaxation time for protecting particles growth. The X-ray diffraction and scanning electron microscope measurements confirmed that the LiFePO{sub 4}/C is olivine structured with the average particle size of 50-100 nm. The spherical LiFePO{sub 4}/C as cathode material showed better electrochemical performance in terms of the specific capacity and the cycling stability, which might be attributed to the highly crystallized phase, small particle distribution and improved conductivity by carbon connection.

  2. Highly Dispersed Pseudo-Homogeneous and Heterogeneous Catalysts Synthesized via Inverse Micelle Solutions for the Liquefaction of Coal

    SciTech Connect

    Hampden-Smith, M.; Kawola, J.S.; Martino, A.; Sault, A.G.; Yamanaka, S.A.

    1999-01-05

    The mission of this project was to use inverse micelle solutions to synthesize nanometer sized metal particles and test the particles as catalysts in the liquefaction of coal and other related reactions. The initial focus of the project was the synthesis of iron based materials in pseudo-homogeneous form. The frost three chapters discuss the synthesis, characterization, and catalyst testing in coal liquefaction and model coal liquefaction reactions of iron based pseudo-homogeneous materials. Later, we became interested in highly dispersed catalysts for coprocessing of coal and plastic waste. Bifunctional catalysts . to hydrogenate the coal and depolymerize the plastic waste are ideal. We began studying, based on our previously devised synthesis strategies, the synthesis of heterogeneous catalysts with a bifunctional nature. In chapter 4, we discuss the fundamental principles in heterogeneous catalysis synthesis with inverse micelle solutions. In chapter 5, we extend the synthesis of chapter 4 to practical systems and use the materials in catalyst testing. Finally in chapter 6, we return to iron and coal liquefaction now studied with the heterogeneous catalysts.

  3. An integrated device with high performance multi-function generators and time-to-digital convertors.

    PubMed

    Qin, X; Shi, Z; Xie, Y; Wang, L; Rong, X; Jia, W; Zhang, W; Du, J

    2017-01-01

    A highly integrated, high performance, and re-configurable device, which is designed for the Nitrogen-Vacancy (N-V) center based quantum applications, is reported. The digital compartment of the device is fully implemented in a Field-Programmable-Gate-Array (FPGA). The digital compartment is designed to manage the multi-function digital waveform generation and the time-to-digital convertors. The device provides two arbitrary-waveform-generator channels which operate at a 1 Gsps sampling rate with a maximum bandwidth of 500 MHz. There are twelve pulse channels integrated in the device with a 50 ps time resolution in both duration and delay. The pulse channels operate with the 3.3 V transistor-transistor logic. The FPGA-based time-to-digital convertor provides a 23-ps time measurement precision. A data accumulation module, which can record the input count rate and the distributions of the time measurement, is also available. A digital-to-analog convertor board is implemented as the analog compartment, which converts the digital waveforms to analog signals with 500 MHz lowpass filters. All the input and output channels of the device are equipped with 50 Ω SubMiniature version A termination. The hardware design is modularized thus it can be easily upgraded with compatible components. The device is suitable to be applied in the quantum technologies based on the N-V centers, as well as in other quantum solid state systems, such as quantum dots, phosphorus doped in silicon, and defect spins in silicon carbide.

  4. An integrated device with high performance multi-function generators and time-to-digital convertors

    NASA Astrophysics Data System (ADS)

    Qin, X.; Shi, Z.; Xie, Y.; Wang, L.; Rong, X.; Jia, W.; Zhang, W.; Du, J.

    2017-01-01

    A highly integrated, high performance, and re-configurable device, which is designed for the Nitrogen-Vacancy (N-V) center based quantum applications, is reported. The digital compartment of the device is fully implemented in a Field-Programmable-Gate-Array (FPGA). The digital compartment is designed to manage the multi-function digital waveform generation and the time-to-digital convertors. The device provides two arbitrary-waveform-generator channels which operate at a 1 Gsps sampling rate with a maximum bandwidth of 500 MHz. There are twelve pulse channels integrated in the device with a 50 ps time resolution in both duration and delay. The pulse channels operate with the 3.3 V transistor-transistor logic. The FPGA-based time-to-digital convertor provides a 23-ps time measurement precision. A data accumulation module, which can record the input count rate and the distributions of the time measurement, is also available. A digital-to-analog convertor board is implemented as the analog compartment, which converts the digital waveforms to analog signals with 500 MHz lowpass filters. All the input and output channels of the device are equipped with 50 Ω SubMiniature version A termination. The hardware design is modularized thus it can be easily upgraded with compatible components. The device is suitable to be applied in the quantum technologies based on the N-V centers, as well as in other quantum solid state systems, such as quantum dots, phosphorus doped in silicon, and defect spins in silicon carbide.

  5. High Speed High Resolution Current Comparator and its Application to Analog to Digital Converter

    NASA Astrophysics Data System (ADS)

    Sridhar, Ranjana; Pandey, Neeta; Bhattacharyya, Asok; Bhatia, Veepsa

    2016-06-01

    This paper introduces a high speed high resolution current comparator which includes the current differencing stage and employs non linear feedback in the gain stage. The usefulness of the proposed comparator is demonstrated by implementing a 3-bit current mode flash analog-to-digital converter (ADC). Simulation program with integrated circuit emphasis (SPICE) simulations have been carried out to verify theoretical proposition and performance parameters of both comparator and ADC are obtained using TSMC 0.18 µm CMOS technology parameters. The current comparator shows a resolution of ±5 nA and a delay of 0.86 ns for current difference of ±1 µA. The impact of process variation on proposed comparator propagation delay has been studied through Monte Carlo simulation and it is found that percentage change in propagation delay in best case is 1.3 % only and in worst case is 9 % only. The ADC exhibits an offset, gain error, differential nonlinearity (DNL) and integral nonlinearity (INL) of 0.102 µA, 0.99, -0.34 LSB and 0.0267 LSB, respectively. The impact of process variation on ADC has also been studied at different process corners.

  6. FERMI: a digital Front End and Readout MIcrosystem for high resolution calorimetry

    NASA Astrophysics Data System (ADS)

    Alexanian, H.; Appelquist, G.; Bailly, P.; Benetta, R.; Berglund, S.; Bezamat, J.; Blouzon, F.; Bohm, C.; Breveglieri, L.; Brigati, S.; Cattaneo, P. W.; Dadda, L.; David, J.; Engström, M.; Genat, J. F.; Givoletti, M.; Goggi, V. G.; Gong, S.; Grieco, G. M.; Hansen, M.; Hentzell, H.; Holmberg, T.; Höglund, I.; Inkinen, S. J.; Kerek, A.; Landi, C.; Ledortz, O.; Lippi, M.; Lofstedt, B.; Lund-Jensen, B.; Maloberti, F.; Mutz, S.; Nayman, P.; Piuri, V.; Polesello, G.; Sami, M.; Savoy-Navarro, A.; Schwemling, P.; Stefanelli, R.; Sundblad, R.; Svensson, C.; Torelli, G.; Vanuxem, J. P.; Yamdagni, N.; Yuan, J.; Ödmark, A.; Fermi Collaboration

    1995-02-01

    We present a digital solution for the front-end electronics of high resolution calorimeters at future colliders. It is based on analogue signal compression, high speed {A}/{D} converters, a fully programmable pipeline and a digital signal processing (DSP) chain with local intelligence and system supervision. This digital solution is aimed at providing maximal front-end processing power by performing waveform analysis using DSP methods. For the system integration of the multichannel device a multi-chip, silicon-on-silicon multi-chip module (MCM) has been adopted. This solution allows a high level of integration of complex analogue and digital functions, with excellent flexibility in mixing technologies for the different functional blocks. This type of multichip integration provides a high degree of reliability and programmability at both the function and the system level, with the additional possibility of customising the microsystem to detector-specific requirements. For enhanced reliability in high radiation environments, fault tolerance strategies, i.e. redundancy, reconfigurability, majority voting and coding for error detection and correction, are integrated into the design.

  7. High-speed optical processing using digital micromirror device

    NASA Astrophysics Data System (ADS)

    Chao, Tien-Hsin; Lu, Thomas; Walker, Brian; Reyes, George

    2014-04-01

    We have designed optical processing architecture and algorithms utilizing the DMD as the input and filter Spatial Light Modulators (SLM). Detailed system analysis will be depicted. Experimental demonstration, for the first time, showing that a complex-valued spatial filtered can be successfully written on the DMDSLM using a Computer Generated Hologram (CGH) [1] encoding technique will also be provided. The high-resolution, high-bandwidth provided by the DMD and its potential low cost due to mass production will enable its vast defense and civil application.

  8. A high performance cost-effective digital complex correlator for an X-band polarimetry survey.

    PubMed

    Bergano, Miguel; Rocha, Armando; Cupido, Luís; Barbosa, Domingos; Villela, Thyrso; Boas, José Vilas; Rocha, Graça; Smoot, George F

    2016-01-01

    The detailed knowledge of the Milky Way radio emission is important to characterize galactic foregrounds masking extragalactic and cosmological signals. The update of the global sky models describing radio emissions over a very large spectral band requires high sensitivity experiments capable of observing large sky areas with long integration times. Here, we present the design of a new 10 GHz (X-band) polarimeter digital back-end to map the polarization components of the galactic synchrotron radiation field of the Northern Hemisphere sky. The design follows the digital processing trends in radio astronomy and implements a large bandwidth (1 GHz) digital complex cross-correlator to extract the Stokes parameters of the incoming synchrotron radiation field. The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results. The implementation is based on the simultaneous digitized acquisition of the Cartesian components of the two linear receiver polarization channels. The design strategy involves a double data rate acquisition of the ADC interleaved parallel bus, and field programmable gate array device programming at the register transfer mode. The digital core of the back-end is capable of processing 32 Gbps and is built around an Altera field programmable gate array clocked at 250 MHz, 1 GSps analog to digital converters and a clock generator. The control of the field programmable gate array internal signal delays and a convenient use of its phase locked loops provide the timing requirements to achieve the target bandwidths and sensitivity. This solution is convenient for radio astronomy experiments requiring large bandwidth, high functionality, high volume availability and low cost. Of particular interest, this correlator was developed for the Galactic Emission Mapping project and is suitable for large sky area polarization continuum surveys. The solutions may also be adapted to be used at signal processing

  9. A highly parallel microfluidic droplet method enabling single-molecule counting for digital enzyme detection

    PubMed Central

    Guan, Zhichao; Zou, Yuan; Zhang, Mingxia; Lv, Jiangquan; Shen, Huali; Yang, Pengyuan; Zhang, Huimin; Zhu, Zhi; James Yang, Chaoyong

    2014-01-01

    Although digital detection of nucleic acids has been achieved by amplification of single templates in uniform microfluidic droplets and widely used for genetic analysis, droplet-based digital detection of proteins has rarely been reported, largely due to the lack of an efficient target amplification method for protein in droplets. Here, we report a key step towards digital detection of proteins using a highly parallel microfluidic droplet approach for single enzyme molecule detection in picoliter droplets via enzyme catalyzed signal amplification. An integrated microfluidic chip was designed for high throughput uniform droplet generation, monolayer droplet collection, incubation, detection, and release. Single β-galatosidase (β-Gal) molecules and the fluorogenic substrate fluorescein di-β-D-galactopyranoside were injected from two separated inlets to form uniform 20 μm droplets in fluorinated oil at a frequency of 6.6 kHz. About 200 000 droplets were captured as a monolayer in a capture well on-chip for subsequent imaging detection. A series of β-Gal solutions at different concentrations were analyzed at the single-molecule level. With no enzyme present, no droplets were found to fluoresce, while brightly fluorescent droplets were observed under single-enzyme molecule conditions. Droplet fluorescence intensity distribution analysis showed that the distribution of enzyme molecules under single-molecule conditions matched well with theoretical prediction, further proving the feasibility of detecting single enzyme molecules in emulsion droplets. Moreover, the population of fluorescent droplets increased as the β-Gal concentration increased. Based on a digital counting method, the measured concentrations of the enzyme were found to match well with input enzyme concentration, establishing the accuracy of the digital detection method for the quantification of β-Gal enzyme molecules. The capability of highly parallel detection of single enzyme molecules in

  10. Characterization of Vocal Fold Vibration in Sulcus Vocalis Using High-Speed Digital Imaging

    ERIC Educational Resources Information Center

    Yamauchi, Akihito; Yokonishi, Hisayuki; Imagawa, Hiroshi; Sakakibara, Ken-Ichi; Nito, Takaharu; Tayama, Niro; Yamasoba, Tatsuya

    2017-01-01

    Purpose: The aim of the present study was to qualitatively and quantitatively characterize vocal fold vibrations in sulcus vocalis by high-speed digital imaging (HSDI) and to clarify the correlations between HSDI-derived parameters and traditional vocal parameters. Method: HSDI was performed in 20 vocally healthy subjects (8 men and 12 women) and…

  11. Highly Stretchable and UV Curable Elastomers for Digital Light Processing Based 3D Printing.

    PubMed

    Patel, Dinesh K; Sakhaei, Amir Hosein; Layani, Michael; Zhang, Biao; Ge, Qi; Magdassi, Shlomo

    2017-04-01

    Stretchable UV-curable (SUV) elastomers can be stretched by up to 1100% and are suitable for digital-light-processing (DLP)-based 3D-printing technology. DLP printing of these SUV elastomers enables the direct creation of highly deformable complex 3D hollow structures such as balloons, soft actuators, grippers, and buckyball electronical switches.

  12. High School Students' Use of Digital Tools for Learning English Vocabulary in an EFL Context

    ERIC Educational Resources Information Center

    Cojocnean, Diana

    2015-01-01

    This study investigated Romanian high school students' use of digital tools for learning vocabulary in English. Although students have a wide range of technological affordances at their disposal, little is known about how they make use of them or the extent to which they are aware of how to use them in their vocabulary learning. The study features…

  13. Design Principles for "Thriving in Our Digital World": A High School Computer Science Course

    ERIC Educational Resources Information Center

    Veletsianos, George; Beth, Bradley; Lin, Calvin; Russell, Gregory

    2016-01-01

    "Thriving in Our Digital World" is a technology-enhanced dual enrollment course introducing high school students to computer science through project- and problem-based learning. This article describes the evolution of the course and five lessons learned during the design, development, implementation, and iteration of the course from its…

  14. Digital control of high-intensity acoustic testing

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.

    1975-01-01

    A high intensity acoustic test system is reported that consists of a reverberation room measuring 18 feet wide by 21 feet long by 26 feet high, with an internal volume of 10,900 cubic feet. The room is rectangular in shape. Acoustic energy is supplied through two 50-Hz cutoff exponential horns about 12 feet long. Each of the two horns has two transducers rated at 4000 acoustic watts each. A gaseous nitrogen supply is used to supply the energy. The equalized electrical signal is corrected by a circuit designed to compensate for the transducer nonlinearity, then fed into one channel of a phase linear power amplifier, then into the transducer. The amplifiers have been modified to increase their reliability. The acoustic energy in the room is monitored by six B and K 1/2-inch condenser microphones. The electrical signal from each microphone is fed into a six channel real time averager to give a spatial average of the signals.

  15. Digital control of high performance aircraft using adaptive estimation techniques

    NASA Technical Reports Server (NTRS)

    Van Landingham, H. F.; Moose, R. L.

    1977-01-01

    In this paper, an adaptive signal processing algorithm is joined with gain-scheduling for controlling the dynamics of high performance aircraft. A technique is presented for a reduced-order model (the longitudinal dynamics) of a high performance STOL aircraft. The actual controller views the nonlinear behavior of the aircraft as equivalent to a randomly switching sequence of linear models taken from a preliminary piecewise-linear fit of the system nonlinearities. The adaptive nature of the estimator is necessary to select the proper sequence of linear models along the flight trajectory. Nonlinear behavior is approximated by effective switching of the linear models at random times, with durations reflecting aircraft motion in response to pilot commands.

  16. Digital controlling system to the set of high power LEDs

    NASA Astrophysics Data System (ADS)

    Gilewski, Marian; Gryko, Lukasz; Zajac, Andrzej

    2013-07-01

    In the paper is described the concept and architecture of the multi-channel control system for set of high-power LEDs. The broadband source of radiation for prototype illuminator is dedicated to the investigation of Low Level Laser Therapy procedures. The general scheme of the system, detailed schemes, control algorithm and its implementation description in FPGA structure is presented. The temperature conditions and the opportunity to work with a microcomputer are characterized.

  17. Development of the HIDEC inlet integration mode. [Highly Integrated Digital Electronic Control

    NASA Technical Reports Server (NTRS)

    Chisholm, J. D.; Nobbs, S. G.; Stewart, J. F.

    1990-01-01

    The Highly Integrated Digital Electronic Control (HIDEC) development program conducted at NASA-Ames/Dryden will use an F-15 test aircraft for flight demonstration. An account is presently given of the HIDEC Inlet Integration mode's design concept, control law, and test aircraft implementation, with a view to its performance benefits. The enhancement of performance is a function of the use of Digital Electronic Engine Control corrected engine airflow computations to improve the scheduling of inlet ramp positions in real time; excess thrust can thereby be increased by 13 percent at Mach 2.3 and 40,000 ft. Aircraft supportability is also improved through the obviation of inlet controllers.

  18. Development and Utilization of High Precision Digital Elevation Data taken by Airborne Laser Scanner

    NASA Astrophysics Data System (ADS)

    Akutsu, Osamu; Ohta, Masataka; Isobe, Tamio; Ando, Hisamitsu, Noguchi, Takahiro; Shimizu, Masayuki

    2005-03-01

    Disasters caused by heavy rain in urban areas bring a damage such as chaos in the road and railway transport systems, power failure, breakdown of the telephone system and submersion of built up areas, subways and underground shopping arcades, etc. It is important to obtain high precision elevation data which shows the detailed landform because a slight height difference affects damages by flood very considerably. Therefore, The Geographical Survey Institute (GSI) is preparing 5m grid digital terrain model (DTM) based on precise ground elevation data taken by using airborne laser scanner. This paper describes the process and an example of the use of a 5m grid digital data set.

  19. A Digital Bistatic Radar Instrument for High-Latitude Ionospheric E-region Research

    NASA Astrophysics Data System (ADS)

    Huyghebaert, D. R.; Hussey, G. C.; McWilliams, K. A.; St-Maurice, J. P.

    2015-12-01

    A new 50 MHz ionospheric E-region radar is currently being developed and will be operational for the summer of 2016. The radar group in the Institute of Space and Atmospheric Studies (ISAS) at the University of Saskatchewan is designing and building the radar which will be located near the university in Saskatoon, SK, Canada and will have a field of view over Wollaston Lake in northern Saskatchewan. This novel radar will simultaneously obtain high spatial and temporal resolution through the use of a bistatic setup and pulse modulation techniques. The bistatic setup allows the radar to transmit and receive continuously, while pulse modulation techniques allow for enhanced spatial resolution, only constrained by the radio bandwidth licensing available. A ten antenna array will be used on both the transmitter and receiver sides, with each antenna having an independent radio path. This enables complete digital control of the transmitted 1 kW signal at each antenna, allowing for digital beam steering and multimode broadcasting. On the receiver side the raw digitized signal will be recorded from each antenna, allowing for complete digital post-processing to be performed on the data. From the measurements provided using these modern digital radar capabilities, further insights into the physics of E-region phenomena, such as Alfvén waves propagating from the magnetosphere above and ionospheric irregularities, may be investigated.

  20. Energy reconstruction in a highly granularity semi-digital hadronic calorimeter

    SciTech Connect

    Sameh Mannai

    2015-07-01

    A semi-digital hadronic calorimeter using Glass Resistive Plate Chambers (GRPCs) is one of the calorimeters candidates proposed for particle physics experiments at the future electrons collider. It is a high granular calorimeter which is required for application of the particle flow algorithm in order to improve the jet energy resolution as one of the goals of this experiments. We discussed the energy reconstruction, based on digital and semi-Digital methods, to study the effect on the improvement of the single particle energy resolution and the linearity of the detector response. This study was performed with the GEANT4 simulation. Results on the energy resolution and linearity, for negative pions over an energy range from 1 to 100 GeV are presented and compared with different energy reconstruction methods including Artificial Neural Networks. (authors)

  1. Quantifying Human Visible Color Variation from High Definition Digital Images of Orb Web Spiders

    PubMed Central

    Ajuria Ibarra, Helena; Rao, Dinesh

    2016-01-01

    Digital processing and analysis of high resolution images of 30 individuals of the orb web spider Verrucosa arenata were performed to extract and quantify human visible colors present on the dorsal abdomen of this species. Color extraction was performed with minimal user intervention using an unsupervised algorithm to determine groups of colors on each individual spider, which was then analyzed in order to quantify and classify the colors obtained, both spatially and using energy and entropy measures of the digital images. Analysis shows that the colors cover a small region of the visible spectrum, are not spatially homogeneously distributed over the patterns and from an entropic point of view, colors that cover a smaller region on the whole pattern carry more information than colors covering a larger region. This study demonstrates the use of processing tools to create automatic systems to extract valuable information from digital images that are precise, efficient and helpful for the understanding of the underlying biology. PMID:27902724

  2. Low-temperature approach to high-yield and reproducible syntheses of high-quality small-sized PbSe colloidal nanocrystals for photovoltaic applications.

    PubMed

    Ouyang, Jianying; Schuurmans, Carl; Zhang, Yanguang; Nagelkerke, Robbert; Wu, Xiaohua; Kingston, David; Wang, Zhi Yuan; Wilkinson, Diana; Li, Chunsheng; Leek, Donald M; Tao, Ye; Yu, Kui

    2011-02-01

    Small-sized PbSe nanocrystals (NCs) were synthesized at low temperature such as 50-80 °C with high reaction yield (up to 100%), high quality, and high synthetic reproducibility, via a noninjection-based one-pot approach. These small-sized PbSe NCs with their first excitonic absorption in wavelength shorter than 1200 nm (corresponding to size < ∼3.7 nm) were developed for photovoltaic applications requiring a large quantity of materials. These colloidal PbSe NCs, also called quantum dots, are high-quality, in terms of narrow size distribution with a typical standard deviation of ∼7-9%, excellent optical properties with high quantum yield of ∼50-90% and small full width at half-maximum of ∼130-150 nm of their band-gap photoemission peaks, and high storage stability. Our synthetic design aimed at promotion of the formation of PbSe monomers for fast and sizable nucleation with the presence of a large number of nuclei at low temperature. For formation of the PbSe monomer, our low-temperature approach suggests the existence of two pathways of Pb-Se (route a) and Pb-P (route b) complexes. Either pathway may dominate, depending on the method used and its experimental conditions. Experimentally, a reducing/nucleation agent, diphenylphosphine, was added to enhance route b. The present study addresses two challenging issues in the NC community, the monomer formation mechanism and the reproducible syntheses of small-sized NCs with high yield and high quality and large-scale capability, bringing insight to the fundamental understanding of optimization of the NC yield and quality via control of the precursor complex reactivity and thus nucleation/growth. Such advances in colloidal science should, in turn, promote the development of next-generation low-cost and high-efficiency solar cells. Schottky-type solar cells using our PbSe NCs as the active material have achieved the highest power conversion efficiency of 2.82%, in comparison with the same type of solar cells

  3. Digital metamaterials.

    PubMed

    Della Giovampaola, Cristian; Engheta, Nader

    2014-12-01

    Balancing complexity and simplicity has played an important role in the development of many fields in science and engineering. One of the well-known and powerful examples of such balance can be found in Boolean algebra and its impact on the birth of digital electronics and the digital information age. The simplicity of using only two numbers, '0' and '1', in a binary system for describing an arbitrary quantity made the fields of digital electronics and digital signal processing powerful and ubiquitous. Here, inspired by the binary concept, we propose to develop the notion of digital metamaterials. Specifically, we investigate how one can synthesize an electromagnetic metamaterial with a desired permittivity, using as building blocks only two elemental materials, which we call 'metamaterial bits', with two distinct permittivity functions. We demonstrate, analytically and numerically, how proper spatial mixtures of such metamaterial bits lead to elemental 'metamaterial bytes' with effective material parameters that are different from the parameters of the metamaterial bits. We then apply this methodology to several design examples of optical elements, such as digital convex lenses, flat graded-index digital lenses, digital constructs for epsilon-near-zero (ENZ) supercoupling and digital hyperlenses, thus highlighting the power and simplicity of the methodology.

  4. A high speed, wide dynamic range digitizer circuit for photomultiplier tubes

    SciTech Connect

    Yarema, R.J.; Foster, G.W.; Knickerbocker, K.; Sarraj, M.; Tschirhart, R.; Whitmore, J.; Zimmerman, T.; Lindgren, M.

    1994-06-01

    High energy physics experiments running at high interaction rates frequently require long record lengths for determining a level 1 trigger. The easiest way to provide a long event record is by digital means. In applications requiring wide dynamic range, however, digitization of an analog signal to obtain the digital record has been impossible due to lack of high speed, wide range FADCs. One such application is the readout of thousands of photomultiplier tubes in fixed target and colliding beam experiment calorimeters. A circuit has been designed for digitizing PMT signals over a wide dynamic range (17--18 bits) with 8 bits of resolution at rates up to 53 MHz. Output from the circuit is in a floating point format with a 4 bit exponent and an 8 bit mantissa. The heart of the circuit is a full custom integrated circuit called the QIE (Charge Integrator and Encoder). The design of the QIE and associated circuitry reported here permits operation over a 17 bit dynamic range. Tests of the circuit with a PMT input and a pulsed laser have provided respectable results with little off line correction. Performance of the circuit for demanding applications can be significantly enhanced with additional off line correction. Circuit design, packaging issues, and test results of a multirange device are presented for the first time.

  5. Digital avionics susceptibility to high energy radio frequency fields

    NASA Technical Reports Server (NTRS)

    Larsen, William E.

    1988-01-01

    Generally, noncritical avionic systems for transport category aircraft have been designed to meet radio frequency (RF) susceptibility requirements set forth in RTCA DO 160B, environmental conditions and test procedures for airborne equipment. Section 20 of this document controls the electromagnetic interference (EMI) hardening for avionics equipment to levels of 1 and 2 V/m. Currently, US equipment manufacturers are designing flight-critical fly-by-wire avionics to a much higher level. The US Federal Aviation Administration (FAA) has requested that the RTCA SC-135 high-energy radio frequency (HERF) working group develop appropriate testing procedures for section 20 of RTCA DO 160B for radiated and conducted susceptibility at the box and systems level. The FAA has also requested the SAE AE4R committee to address installed systems testing, airframe shielding effects and RF environment monitoring. Emitters of interest include radar (ground, ship, and aircraft) commercial broadcast and TV station, mobile communication, and other transmitters that could possibly affect commercial aircraft.

  6. A polyaniline-coated mechanochemically synthesized tin oxide/graphene nanocomposite for high-power and high-energy lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ye, Fei; Zhao, Bote; Ran, Ran; Shao, Zongping

    2015-09-01

    Although intensive efforts have been made during the past decades, development of an anode material with high specific capacity and stable cycling performance for lithium-ion batteries (LIBs) using a cost-effective preparation method still remains challenging. Herein, we report a polyaniline (PANI)-coated mechanochemically synthesized SnO2/graphene (SG) nanocomposite via in situ polymerization. PANI-coated nanocomposites are successfully prepared with different raw material mass ratios (aniline:SG, 0.15:1, 0.2:1, 0.25:1). The nanocomposite with initial aniline:SG mass ratio of 0.2:1 (20%PANI-SG) contains an optimal structure housing genuine PANI nanofibers as conductive bridges and a relatively high surface area of 158.5 m2 g-1; furthermore, it exhibits a stable cycling performance over 100 cycles at high current density (1000 mA g-1) with a specific capacity of more than twice that of the starting SG electrode at the 100th cycle. Additionally, this material achieved an outstanding cycling rate with current densities changing stepwise from 100 to 3000 mA g-1 and back, and exhibited a specific capacity of 467 mA h g-1 even at 2000 mA g-1. In terms of the electrochemical stability, rate capability and cost-effective preparation process, the PANI-SG nanocomposite is a viable anode material for next-generation high-power and high-energy LIBs.

  7. StreaMorph: A Case for Synthesizing Energy-Efficient Adaptive Programs Using High-Level Abstractions

    DTIC Science & Technology

    2013-08-12

    awards \\#0720882 ( CSR -EHS: PRET), \\#0931843 (CPS: Large: ActionWebs), and \\#1035672 (CPS: Medium: Ptides)), the Naval Research Laboratory (NRL \\#N0013-12...1- G015), and the following companies : Bosch, National Instruments, and Toyota. StreaMorph: A Case for Synthesizing Energy-Efficient Adaptive Programs

  8. Vibration measurement of a miniature component by high-speed image-plane digital holographic microscopy

    SciTech Connect

    Fu Yu; Shi Hongjian; Miao Hong

    2009-04-10

    Measuring deformation of vibrating specimens whose dimensions are in the submillimeter range introduces a number of difficulties using laser interferometry. Normal interferometry is not suitable because of a phase ambiguity problem. In addition, the noise effect is much more serious in the measurement of small objects because a high-magnification lens is used. We present a method for full-field measurement of displacement, velocity, and acceleration of a vibrating miniature object based on image-plane digital holographic microscopy. A miniature cantilever beam is excited by a piezoelectric transducer stage with a sinusoidal configuration. A sequence of digital holograms is captured using a high-speed digital holographic microscope. Windowed Fourier analysis is applied in the spatial and spatiotemporal domains to extract the displacement, velocity and acceleration. The result shows that a combination of image-plane digital holographic microscopy and windowed Fourier analyses can be used to study vibration without encountering a phase ambiguity problem, and one can obtain instantaneous kinematic parameters on each point.

  9. High critical current density and improved flux pinning in bulk MgB2 synthesized by Ag addition

    NASA Astrophysics Data System (ADS)

    Shekhar, Chandra; Giri, Rajiv; Tiwari, R. S.; Srivastava, O. N.; Malik, S. K.

    2007-02-01

    In the present investigation, we report a systematic study of Ag admixing in MgB2 prepared by solid-state reaction at ambient pressure. All the samples in the present investigation have been subjected to structural/ microstructural characterization employing x-ray diffraction and transmission electron microscopic (TEM) techniques. The magnetization measurements were performed by physical property measurement system. The TEM investigations reveal the formation of MgAg nanoparticles in Ag admixed samples. These nanoparticles may enhance critical current density due to their size (˜5-20nm ) which is compatible with the coherence length of MgB2 (˜5-6nm ). In order to study the flux pinning effect of Ag admixing in MgB2, the evaluation of intragrain critical current density (Jc) has been carried out through magnetic measurements on the fine powdered version of the as synthesized samples. The optimum result on intragrain Jc is obtained for 10at.% Ag admixed sample at 5K. This corresponds to ˜9.23×107A /cm2 in self-field, ˜5.82×107A/cm2 at 1T, ˜4.24×106A/cm2 at 3.6T, and ˜1.52×105A/cm2 at 5T. However, intragrain Jc values for MgB2 sample without Ag admixing are ˜2.59×106, ˜1.09×106, ˜4.53×104, and 2.91×103A /cm2 at 5K in self-field, 1T, 3.6T, and 5T, respectively. The high value of intragrain Jc for Ag admixed MgB2 superconductor has been attributed to the inclusion of MgAg nanoparticles into the crystal matrix of MgB2, which are capable of providing effective flux pinning centers. A feasible correlation between microstructural features and superconducting properties has been put forward.

  10. Crystal structures and compressibility of novel iron borides Fe2B7 and FexB50 synthesized at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Bykova, E.; Gou, H.; Bykov, M.; Hanfland, M.; Dubrovinsky, L.; Dubrovinskaia, N.

    2015-10-01

    We present here a detailed description of the crystal structures of novel iron borides, Fe2B7 and FexB50 with various iron content (x=1.01(1), 1.04(1), 1.32(1)), synthesized at high pressures and high temperatures. As revealed by high-pressure single-crystal X-ray diffraction, the structure of Fe2B7 possesses short incompressible B-B bonds, which make it as stiff as diamond in one crystallographic direction. The volume compressibility of Fe2B7 (the bulk modulus K0= 259(1.8) GPa, K0‧= 4 (fixed)) is even lower than that of FeB4 and comparable with that of MnB4, known for high bulk moduli among 3d metal borides. FexB50 adopts the structure of the tetragonal δ-B, in which Fe atoms occupy an interstitial position. FexB50 does not show considerable anisotropy in the elastic behavior.

  11. High accuracy digital aging monitor based on PLL-VCO circuit

    NASA Astrophysics Data System (ADS)

    Yuejun, Zhang; Zhidi, Jiang; Pengjun, Wang; Xuelong, Zhang

    2015-01-01

    As the manufacturing process is scaled down to the nanoscale, the aging phenomenon significantly affects the reliability and lifetime of integrated circuits. Consequently, the precise measurement of digital CMOS aging is a key aspect of nanoscale aging tolerant circuit design. This paper proposes a high accuracy digital aging monitor using phase-locked loop and voltage-controlled oscillator (PLL-VCO) circuit. The proposed monitor eliminates the circuit self-aging effect for the characteristic of PLL, whose frequency has no relationship with circuit aging phenomenon. The PLL-VCO monitor is implemented in TSMC low power 65 nm CMOS technology, and its area occupies 303.28 × 298.94 μm2. After accelerating aging tests, the experimental results show that PLL-VCO monitor improves accuracy about high temperature by 2.4% and high voltage by 18.7%.

  12. A Highly Sensitive CMOS Digital Hall Sensor for Low Magnetic Field Applications

    PubMed Central

    Xu, Yue; Pan, Hong-Bin; He, Shu-Zhuan; Li, Li

    2012-01-01

    Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated in 0.18 μm high voltage CMOS technology for low field applications. The sensor consists of a switched cross-shaped Hall plate and a novel signal conditioner. It effectively eliminates offset and low frequency 1/f noise by applying a dynamic quadrature offset cancellation technique. The measured results show the optimal Hall plate achieves a high current related sensitivity of about 310 V/AT. The whole sensor has a remarkable ability to measure a minimum ±2 mT magnetic field and output a digital Hall signal in a wide temperature range from −40 °C to 120 °C. PMID:22438758

  13. A highly sensitive CMOS digital Hall sensor for low magnetic field applications.

    PubMed

    Xu, Yue; Pan, Hong-Bin; He, Shu-Zhuan; Li, Li

    2012-01-01

    Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated in 0.18 μm high voltage CMOS technology for low field applications. The sensor consists of a switched cross-shaped Hall plate and a novel signal conditioner. It effectively eliminates offset and low frequency 1/f noise by applying a dynamic quadrature offset cancellation technique. The measured results show the optimal Hall plate achieves a high current related sensitivity of about 310 V/AT. The whole sensor has a remarkable ability to measure a minimum ± 2 mT magnetic field and output a digital Hall signal in a wide temperature range from -40 °C to 120 °C.

  14. Programmable electronic synthesized capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  15. Touchdown digital polymerase chain reaction for quantification of highly conserved sequences in the HIV-1 genome.

    PubMed

    De Spiegelaere, Ward; Malatinkova, Eva; Kiselinova, Maja; Bonczkowski, Pawel; Verhofstede, Chris; Vogelaers, Dirk; Vandekerckhove, Linos

    2013-08-15

    Digital polymerase chain reaction (PCR) is an emerging absolute quantification method based on the limiting dilution principle and end-point PCR. This methodology provides high flexibility in assay design without influencing quantitative accuracy. This article describes an assay to quantify HIV DNA that targets a highly conserved region of the HIV-1 genome that hampers optimal probe design. To maintain high specificity and allow probe binding and hydrolysis of a probe with low melting temperature, a two-stage touchdown PCR was designed with a first round of amplification at high temperature and a subsequent round at low temperature to allow accumulation of fluorescence.

  16. Propulsion control experience used in the Highly Integrated Digital Electronic Control (HIDEC) program

    NASA Technical Reports Server (NTRS)

    Myers, L. P.; Burcham, F. W., Jr.

    1984-01-01

    The highly integrated digital electronic control (HIDEC) program will integrate the propulsion and flight control systems on an F-15 airplane at NASA Ames Research Center's Dryden Flight Research Facility. Ames-Dryden has conducted several propulsion control programs that have contributed to the HIDEC program. The digital electronic engine control (DEEC) flight evaluation investigated the performance and operability of the F100 engine equipped with a full-authority digital electronic control system. Investigations of nozzle instability, fault detection and accommodation, and augmentor transient capability provided important information for the HIDEC program. The F100 engine model derivative (EMD) was also flown in the F-15 airplane, and airplane performance was significantly improved. A throttle response problem was found and solved with a software fix to the control logic. For the HIDEC program, the F100 EMD engines equipped with DEEC controls will be integrated with the digital flight control system. The control modes to be implemented are an integrated flightpath management mode and an integrated adaptive engine control system mode. The engine control experience that will be used in the HIDEC program is discussed.

  17. A high capacity data recording device based on a digital audio processor and a video cassette recorder.

    PubMed Central

    Bezanilla, F

    1985-01-01

    A modified digital audio processor, a video cassette recorder, and some simple added circuitry are assembled into a recording device of high capacity. The unit converts two analog channels into digital form at 44-kHz sampling rate and stores the information in digital form in a common video cassette. Bandwidth of each channel is from direct current to approximately 20 kHz and the dynamic range is close to 90 dB. The total storage capacity in a 3-h video cassette is 2 Gbytes. The information can be retrieved in analog or digital form. PMID:3978213

  18. Simulation of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

    NASA Astrophysics Data System (ADS)

    Meng, X. T.; Levin, D. S.; Chapman, J. W.; Zhou, B.

    2016-09-01

    The ATLAS Muon Spectrometer endcap thin-Resistive Plate Chamber trigger project compliments the New Small Wheel endcap Phase-1 upgrade for higher luminosity LHC operation. These new trigger chambers, located in a high rate region of ATLAS, will improve overall trigger acceptance and reduce the fake muon trigger incidence. These chambers must generate a low level muon trigger to be delivered to a remote high level processor within a stringent latency requirement of 43 bunch crossings (1075 ns). To help meet this requirement the High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by CERN Microelectronics group, has been proposed for the digitization of the fast front end detector signals. This paper investigates the HPTDC performance in the context of the overall muon trigger latency, employing detailed behavioral Verilog simulations in which the latency in triggerless mode is measured for a range of configurations and under realistic hit rate conditions. The simulation results show that various HPTDC operational configurations, including leading edge and pair measurement modes can provide high efficiency (>98%) to capture and digitize hits within a time interval satisfying the Phase-1 latency tolerance.

  19. High-throughput characterization of film thickness in thin film materials libraries by digital holographic microscopy.

    PubMed

    Lai, Yiu Wai; Krause, Michael; Savan, Alan; Thienhaus, Sigurd; Koukourakis, Nektarios; Hofmann, Martin R; Ludwig, Alfred

    2011-10-01

    A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.

  20. Digital camera workflow for high dynamic range images using a model of retinal processing

    NASA Astrophysics Data System (ADS)

    Tamburrino, Daniel; Alleysson, David; Meylan, Laurence; Süsstrunk, Sabine

    2008-02-01

    We propose a complete digital camera workflow to capture and render high dynamic range (HDR) static scenes, from RAW sensor data to an output-referred encoded image. In traditional digital camera processing, demosaicing is one of the first operations done after scene analysis. It is followed by rendering operations, such as color correction and tone mapping. In our workflow, which is based on a model of retinal processing, most of the rendering steps are performed before demosaicing. This reduces the complexity of the computation, as only one third of the pixels are processed. This is especially important as our tone mapping operator applies local and global tone corrections, which is usually needed to well render high dynamic scenes. Our algorithms efficiently process HDR images with different keys and different content.

  1. BrainMaps.org - Interactive High-Resolution Digital Brain Atlases and Virtual Microscopy.

    PubMed

    Mikula, Shawn; Stone, James M; Jones, Edward G

    2008-01-01

    BrainMaps.org is an interactive high-resolution digital brain atlas and virtual microscope that is based on over 20 million megapixels of scanned images of serial sections of both primate and non-primate brains and that is integrated with a high-speed database for querying and retrieving data about brain structure and function over the internet. Complete brain datasets for various species, including Homo sapiens, Macaca mulatta, Chlorocebus aethiops, Felis catus, Mus musculus, Rattus norvegicus, and Tyto alba, are accessible online. The methods and tools we describe are useful for both research and teaching, and can be replicated by labs seeking to increase accessibility and sharing of neuroanatomical data. These tools offer the possibility of visualizing and exploring completely digitized sections of brains at a sub-neuronal level, and can facilitate large-scale connectional tracing, histochemical and stereological analyses.

  2. Incorporating Functional Digital Literacy Skills as Part of the Curriculum for High School Students with Intellectual Disability

    ERIC Educational Resources Information Center

    Cihak, David F.; Wright, Rachel; Smith, Cate C.; McMahon, Don; Kraiss, Kelly

    2015-01-01

    The purpose of this study was to examine the effects of teaching functional digital literacy skills to three high school students with intellectual disability. Functional digital literacy skills included sending and receiving email messages, organizing social bookmarking to save, share, and access career websites, and accessing cloud storage to…

  3. A high-speed Analog-to-Digital converter using Josephson Self-Gating-AND comparators

    NASA Astrophysics Data System (ADS)

    Petersen, D. A.; Ho, H.; Jewett, R. E.; Nakajima, K.; Nandakumar, V.; Spargo, J. W.; van Duzer, T.

    1985-03-01

    A Josephson Analog-to-Digital (A/D) converter which employs Self-Gating-AND (SGA) circuits as comparators has been designed and experimentally investigated. A functional description of the SGA is presented and the design of a four-bit A/D converter is described. High-speed measurements demonstrate four-bit quantization of 280 MHz sinusiodal inputs, and three-bit quantization of 499 MHz inputs at a 1.0 GHz conversion rate.

  4. Low-Cutoff, High-Pass Digital Filtering of Neural Signals

    NASA Technical Reports Server (NTRS)

    Mojarradi,Mohammad; Johnson, Travis; Ortiz, Monico; Cunningham, Thomas; Andersen, Richard

    2004-01-01

    The figure depicts the major functional blocks of a system, now undergoing development, for conditioning neural signals acquired by electrodes implanted in a brain. The overall functions to be performed by this system can be summarized as preamplification, multiplexing, digitization, and high-pass filtering. Other systems under development for recording neural signals typically contain resistor-capacitor analog low-pass filters characterized by cutoff frequencies in the vicinity of 100 Hz. In the application for which this system is being developed, there is a requirement for a cutoff frequency of 5 Hz. Because the resistors needed to obtain such a low cutoff frequency would be impractically large, it was decided to perform low-pass filtering by use of digital rather than analog circuitry. In addition, it was decided to timemultiplex the digitized signals from the multiple input channels into a single stream of data in a single output channel. The signal in each input channel is first processed by a preamplifier having a voltage gain of approximately 50. Embedded in each preamplifier is a low-pass anti-aliasing filter having a cutoff frequency of approximately 10 kHz. The anti-aliasing filters make it possible to couple the outputs of the preamplifiers to the input ports of a multiplexer. The output of the multiplexer is a single stream of time-multiplexed samples of analog signals. This stream is processed by a main differential amplifier, the output of which is sent to an analog-to-digital converter (ADC). The output of the ADC is sent to a digital signal processor (DSP).

  5. Virtual microscopy: high resolution digital photomicrography as a tool for light microscopy simulation.

    PubMed

    Felten, C L; Strauss, J S; Okada, D H; Marchevsky, A M

    1999-04-01

    Recent advances in microcomputers and high resolution digital video cameras provide pathologists the opportunity to combine precision optics with digital imaging technology and develop new educational and research tools. We review recent advances in virtual microscopy and describe techniques for viewing digital images using a microcomputer-based workstation to simulate light microscopic examination, including scanning at low power to select features of interest and zooming to increase magnification. Hardware and software components necessary to acquire digital images of histological and cytological slides, and closely simulate their examination under a light microscope are discussed. The workstation is composed of a MicroLumina digital scanning camera (Leaf Systems, Southborough, MA), light microscope (Olympus Optical Co., Lake Success, NY), Pentium (Intel Corp., Santa Clara, CA) 166 MHz microcomputer configured with 64 megabytes of random access memory (RAM), a MGA Millenium Powerdesk graphics card (Matrox Graphics, Inc., Montreal, Canada) and Photoshop software (Adobe Systems Inc., San Jose, CA) running in a Windows 95 (Microsoft Corp., Redmond, WA) environment. Images with spatial resolutions of up to 2700 x 3400 pixels in 36-bit color, can be displayed simultaneously as distinct images in a montage, or merged into a single composite image file to highlight significant features of a histological or cytological slide. These image files are saved in Joint Photographers Experts Group (JPEG) format using compression ratios of up to 80:1 without detectable visual degradation. The advantages and technical limitations of various workstation components are addressed and applications of this technology for pathology education, proficiency testing, telepathology, and database development are discussed.

  6. High-speed digital color fringe projection technique for three-dimensional facial measurements

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Yang; Chang, Li-Jen; Wang, Chung-Yi

    2016-04-01

    Digital fringe projection techniques have been widely studied in industrial applications because of the advantages of high accuracy, fast acquisition and non-contact operation. In this study, a single-shot high-speed digital color fringe projection technique is proposed to measure three-dimensional (3-D) facial features. The light source used in the measurement system is structured light with color fringe patterns. A projector with digital light processing is used as light source to project color structured light onto face. The distorted fringe pattern image is captured by the 3-CCD color camera and encoded into red, green and blue channels. The phase-shifting algorithm and quality guided path unwrapping algorithm are used to calculate absolute phase map. The detecting angle of the color camera is adjusted by using a motorized stage. Finally, a complete 3-D facial feature is obtained by our technique. We have successfully achieved simultaneous 3-D phase acquisition, reconstruction and exhibition at a speed of 0.5 s. The experimental results may provide a novel, high accuracy and real-time 3-D shape measurement for facial recognition system.

  7. Mechanochemically synthesized sub-5 nm sized CuS quantum dots with high visible-light-driven photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Li, Shun; Ge, Zhen-Hua; Zhang, Bo-Ping; Yao, Yao; Wang, Huan-Chun; Yang, Jing; Li, Yan; Gao, Chao; Lin, Yuan-Hua

    2016-10-01

    We report a simple mechanochemical ball milling method for synthesizing monodisperse CuS quantum dots (QDs) with sizes as small as sub-5 nm. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The CuS QDs exhibited excellent visible-light-driven photocatalytic activity and stability for degradation of Rodanmine B aqueous solution as Fenton-like reagents. Our study opens the opportunity to low-cost and facile synthesis of QDs in large scale for future industrial applications.

  8. Using geomorphological maps to improve digital elevation models in high mountains environments

    NASA Astrophysics Data System (ADS)

    Micheletti, Natan; Lane, Stuart; Chandler, Jim; Lambiel, Christophe

    2013-04-01

    Whilst current digital elevation modeling has been substantially aided by ground-based technologies, understanding environmental change impacts in mountain environments over longer timescales requires unlocking of the information held in historical aerial images. These are commonly available from the 1940s for the European Alps and digital photogrammetric approaches have been established for using such data sources to create precise digital elevation models (precise to better than c. ±0.5 m) over large spatial scales (10s and 100s of km2) that can be used to quantify erosion and deposition in response to recent environmental change. In this paper, we show why geomorphological maps are essential for this development for two reasons. The first is as expected: interpreting catchment scale patterns of erosion and deposition requires reference to the underlying spatial assemblage of landforms present. Digital geomorphological maps can be used to do this, and through classifying erosion and deposition patterns by landform, can be used to identify: those elements of the landscape most sensitive to recent environmental change; and their spatial organization, something that is central to how they interact together to drive sediment flux. The second reason is more surprising. In Alpine environments, the quality of estimation of elevation by digital photogrammetry can be spatially variable and uncertain due to local topography (occlusion caused by sudden elevation changes, areas with large elevation ranges) or varying image texture. Tests on the performance of stereomatching algorithms, including the filtering necessary to guarantee the quality of derived DEM data, show that data quality is highly variable between landform types within a given landscape. Generating high quality DEMs is therefore improved if geomorphological maps are used to define such inherent spatial variability during data processing. Here, we demonstrate these two points using aerial imagery for Val d

  9. Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology.

    PubMed

    Strle, Drago; Nahtigal, Uroš; Batistell, Graciele; Zhang, Vincent Chi; Ofner, Erwin; Fant, Andrea; Sturm, Johannes

    2015-07-22

    This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode's current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm(2) of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA.

  10. Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

    PubMed Central

    Strle, Drago; Nahtigal, Uroš; Batistell, Graciele; Zhang, Vincent Chi; Ofner, Erwin; Fant, Andrea; Sturm, Johannes

    2015-01-01

    This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. PMID:26205275

  11. High-speed 3D digital image correlation vibration measurement: Recent advancements and noted limitations

    NASA Astrophysics Data System (ADS)

    Beberniss, Timothy J.; Ehrhardt, David A.

    2017-03-01

    A review of the extensive studies on the feasibility and practicality of utilizing high-speed 3 dimensional digital image correlation (3D-DIC) for various random vibration measurement applications is presented. Demonstrated capabilities include finite element model updating utilizing full-field 3D-DIC static displacements, modal survey natural frequencies, damping, and mode shape results from 3D-DIC are baselined against laser Doppler vibrometry (LDV), a comparison between foil strain gage and 3D-DIC strain, and finally the unique application to a high-speed wind tunnel fluid-structure interaction study. Results show good agreement between 3D-DIC and more traditional vibration measurement techniques. Unfortunately, 3D-DIC vibration measurement is not without its limitations, which are also identified and explored in this study. The out-of-plane sensitivity required for vibration measurement for 3D-DIC is orders of magnitude less than LDV making higher frequency displacements difficult to sense. Furthermore, the digital cameras used to capture the DIC images have no filter to eliminate temporal aliasing of the digitized signal. Ultimately DIC is demonstrated as a valid alternative means to measure structural vibrations while one unique application achieves success where more traditional methods would fail.

  12. Development of High Speed Digital Camera: EXILIM EX-F1

    NASA Astrophysics Data System (ADS)

    Nojima, Osamu

    The EX-F1 is a high speed digital camera featuring a revolutionary improvement in burst shooting speed that is expected to create entirely new markets. This model incorporates a high speed CMOS sensor and a high speed LSI processor. With this model, CASIO has achieved an ultra-high speed 60 frames per second (fps) burst rate for still images, together with 1,200 fps high speed movie that captures movements which cannot even be seen by human eyes. Moreover, this model can record movies at full High-Definition. After launching it into the market, it was able to get a lot of high appraisals as an innovation camera. We will introduce the concept, features and technologies about the EX-F1.

  13. High-description image acquisition for digital archiving of rare books

    NASA Astrophysics Data System (ADS)

    Kashimura, Masaaki; Nakajima, Toshifumi; Maeda, Taizo; Onda, Norikazu; Saito, Hideo; Ozawa, Shinji

    1998-12-01

    At first in this paper, we given an outline of activity of the Humanities Media Interface (HUMI) Project. This project was established by Keio University for the purpose of digital archiving of rare books held in Keio University Library, and of realizing a research oriented digital library. Then our way of acquiring rare book images of super high definition is introduced and image compensation method for acquiring just- front view of page using the 3-D information extracted from the shape of top line of the page area depicted in the image is proposed. Our approach of acquiring higher resolution image by joining close-up partial images of a page is also introduced. The proposing image adjustment method is extended for partial images of a page as preprocess of joining them together. In the experiment, well-adjusted and joined page images could be obtained.

  14. Superresolved digital in-line holographic microscopy for high-resolution lensless biological imaging.

    PubMed

    Micó, Vicente; Zalevsky, Zeev

    2010-01-01

    Digital in-line holographic microscopy (DIHM) is a modern approach capable of achieving micron-range lateral and depth resolutions in three-dimensional imaging. DIHM in combination with numerical imaging reconstruction uses an extremely simplified setup while retaining the advantages provided by holography with enhanced capabilities derived from algorithmic digital processing. We introduce superresolved DIHM incoming from time and angular multiplexing of the sample spatial frequency information and yielding in the generation of a synthetic aperture (SA). The SA expands the cutoff frequency of the imaging system, allowing submicron resolutions in both transversal and axial directions. The proposed approach can be applied when imaging essentially transparent (low-concentration dilutions) and static (slow dynamics) samples. Validation of the method for both a synthetic object (U.S. Air Force resolution test) to quantify the resolution improvement and a biological specimen (sperm cells biosample) are reported showing the generation of high synthetic numerical aperture values working without lenses.

  15. A high-resolution time-to-digital converter using a three-level resolution

    NASA Astrophysics Data System (ADS)

    Dehghani, Asma; Saneei, Mohsen; Mahani, Ali

    2016-08-01

    In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.

  16. Digital Signal Processors for Cryogenic High-Resolution X-Ray Detector Readout

    SciTech Connect

    Friedrich, S; Drury, O; Bechstein, S; Henning, W; Momayezi, M

    2003-01-01

    The authors are developing fast digital signal processors (DSPs) to read out superconducting high-resolution X-ray detectors with on-line pulse processing. For superconducting tunnel junction (STJ) detector read-out, the DSPs offer on-line filtering, rise time discrimination and pile-up rejection. Compared to analog pulse processing, DSP readout somewhat degrades the detector resolution, but improves the spectral purity of the detector response. They discuss DSP performance with the 9-channel STJ array for synchrotron-based high-resolution X-ray spectroscopy.

  17. Review of The SIAM 100-Digit Challenge: A Study in High-Accuracy Numerical Computing

    SciTech Connect

    Bailey, David

    2005-01-25

    In the January 2002 edition of SIAM News, Nick Trefethen announced the '$100, 100-Digit Challenge'. In this note he presented ten easy-to-state but hard-to-solve problems of numerical analysis, and challenged readers to find each answer to ten-digit accuracy. Trefethen closed with the enticing comment: 'Hint: They're hard! If anyone gets 50 digits in total, I will be impressed.' This challenge obviously struck a chord in hundreds of numerical mathematicians worldwide, as 94 teams from 25 nations later submitted entries. Many of these submissions exceeded the target of 50 correct digits; in fact, 20 teams achieved a perfect score of 100 correct digits. Trefethen had offered $100 for the best submission. Given the overwhelming response, a generous donor (William Browning, founder of Applied Mathematics, Inc.) provided additional funds to provide a $100 award to each of the 20 winning teams. Soon after the results were out, four participants, each from a winning team, got together and agreed to write a book about the problems and their solutions. The team is truly international: Bornemann is from Germany, Laurie is from South Africa, Wagon is from the USA, and Waldvogel is from Switzerland. This book provides some mathematical background for each problem, and then shows in detail how each of them can be solved. In fact, multiple solution techniques are mentioned in each case. The book describes how to extend these solutions to much larger problems and much higher numeric precision (hundreds or thousands of digit accuracy). The authors also show how to compute error bounds for the results, so that one can say with confidence that one's results are accurate to the level stated. Numerous numerical software tools are demonstrated in the process, including the commercial products Mathematica, Maple and Matlab. Computer programs that perform many of the algorithms mentioned in the book are provided, both in an appendix to the book and on a website. In the process, the

  18. A facile approach to synthesize stable CNTs@MnO electrocatalyst for high energy lithium oxygen batteries

    PubMed Central

    Luo, Wen-Bin; Chou, Shu-Lei; Jia-Zhao Wang; Zhai, Yu-Chun; Liu, Hua-Kun

    2015-01-01

    A composite of manganese monoxide loaded onto carbon nanotubes (CNTs@MnO) has been synthesized by a facile approach, in which the CNTs form a continuous conductive network connecting the electrocatalyst MnO nanoparticles together to facilitate good electrochemical performance. The electrocatalyst MnO shows favourable rechargeability, and good phase and morphology stability in lithium oxygen batteries. Excellent cycling performance is also demonstrated, in which the terminal voltage is higher than 2.4 V after 100 cycles at 0.4 mA cm−2, with 1000 mAh g−1(composite) capacity. Therefore, this hybrid material is promising for use as a cathode material for lithium oxygen batteries. PMID:25634100

  19. Synthesizing photovoltaic thin films of high quality copper-zinc-tin alloy with at least one chalcogen species

    DOEpatents

    Teeter, Glenn; Du, Hui; Young, Matthew

    2013-08-06

    A method for synthesizing a thin film of copper, zinc, tin, and a chalcogen species ("CZTCh" or "CZTSS") with well-controlled properties. The method includes depositing a thin film of precursor materials, e.g., approximately stoichiometric amounts of copper (Cu), zinc (Zn), tin (Sn), and a chalcogen species (Ch). The method then involves re-crystallizing and grain growth at higher temperatures, e.g., between about 725 and 925 degrees K, and annealing the precursor film at relatively lower temperatures, e.g., between 600 and 650 degrees K. The processing of the precursor film takes place in the presence of a quasi-equilibrium vapor, e.g., Sn and chalcogen species. The quasi-equilibrium vapor is used to maintain the precursor film in a quasi-equilibrium condition to reduce and even prevent decomposition of the CZTCh and is provided at a rate to balance desorption fluxes of Sn and chalcogens.

  20. High-resolution, high-speed, three-dimensional video imaging with digital fringe projection techniques.

    PubMed

    Ekstrand, Laura; Karpinsky, Nikolaus; Wang, Yajun; Zhang, Song

    2013-12-03

    Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces. Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth. However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras(1). The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera's field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation. Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop. DFP systems can also achieve the same measurement resolution as the camera. For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in(1-5)). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30 Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame(6,7). Binary defocusing DFP methods can achieve even greater speeds(8). Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis(9), facial animation(10), cardiac mechanics studies(11), and fluid surface measurements, but many other potential applications exist. This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

  1. High performance digital read out integrated circuit (DROIC) for infrared imaging

    NASA Astrophysics Data System (ADS)

    Mizuno, Genki; Olah, Robert; Oduor, Patrick; Dutta, Achyut K.; Dhar, Nibir K.

    2016-05-01

    Banpil Photonics has developed a high-performance Digital Read-Out Integrated Circuit (DROIC) for image sensors and camera systems targeting various military, industrial and commercial Infrared (IR) imaging applications. The on-chip digitization of the pixel output eliminates the necessity for an external analog-to-digital converter (ADC), which not only cuts costs, but also enables miniaturization of packaging to achieve SWaP-C camera systems. In addition, the DROIC offers new opportunities for greater on-chip processing intelligence that are not possible in conventional analog ROICs prevalent today. Conventional ROICs, which typically can enhance only one high performance attribute such as frame rate, power consumption or noise level, fail when simultaneously targeting the most aggressive performance requirements demanded in imaging applications today. Additionally, scaling analog readout circuits to meet such requirements leads to expensive, high-power consumption with large and complex systems that are untenable in the trend towards SWaP-C. We present the implementation of a VGA format (640x512 pixels 15μm pitch) capacitivetransimpedance amplifier (CTIA) DROIC architecture that incorporates a 12-bit ADC at the pixel level. The CTIA pixel input circuitry has two gain modes with programmable full-well capacity values of 100K e- and 500K e-. The DROIC has been developed with a system-on-chip architecture in mind, where all the timing and biasing are generated internally without requiring any critical external inputs. The chip is configurable with many parameters programmable through a serial programmable interface (SPI). It features a global shutter, low power, and high frame rates programmable from 30 up 500 frames per second in full VGA format supported through 24 LVDS outputs. This DROIC, suitable for hybridization with focal plane arrays (FPA) is ideal for high-performance uncooled camera applications ranging from near IR (NIR) and shortwave IR (SWIR) to mid

  2. Application of PLC in digitization control intelligence can-body high-speed resitance welding machine

    NASA Astrophysics Data System (ADS)

    Chen, Shaobo; Zhang, Ziqiang; Yan, Qiusheng; Zheng, Zhidan; Li, Yang; Zhang, Tianyu

    2003-09-01

    The application of position servo synchronously tracking system constituted with PLC and general AC servo system in digitalization control intelligence can-body high-speed resistance welding machine is introduced in this paper. By studying the digitalization control system of automatic can-body resistance welding machine, technologic upgrade of product is made, and application of PLC in controlling general AC servo motor multi-axes ganged system to replace conventional mechanical ganged mechanism is developed. It makes the coordination of movements between machine actions can be ensured and every correlative actions can quickly and precisely run synchronously, quondam mechanical branching driving can be replaced, and "mechanical locking" between quondam movements can be changed to the "electronic locking," complex mechanical structures such as cams, stepless speed changing machines and universal joints and so on can be omitted, so the working capability of whole machine can effectively be enhanced and synchronization between the machine actions can rapidly be reached. The application realizes digitalization process control, enhances reliability, stability and manufacturing efficiency of the machine, and reduces the manufacturing cost.

  3. Digital modulation schemes for high speed transmission through low bandwidth lowpass analog links

    NASA Technical Reports Server (NTRS)

    Andrawis, Alfred S.; Flippin, Quentin J.

    1995-01-01

    Existing NTSC (National Television System Committee) standard will be phased out and replaced with HDTV (High Definition Television) standard within the next 10 years. Accordingly, the existing video network system operated by NASA will become obsolete and requires either replacement or modification to accommodate digital transmission. Network replacement is extremely expensive, hence, several digital modulation schemes are investigated in this report to accomplish digital transmission over existing analog links saving NASA from the cost of network replacement. There are two competing transmission systems available for HDTV transmission over limited bandwidth channels. The cost and performance of the two competing schemes are remarkably similar. However, the input data rate in such a case is limited to 40 Mbit/s. Transmission of higher data rates is possible using simple signal processing techniques. On the other hand, a third transmission system, multilevel pulse amplitude modulation (M-PAM) is proposed. M-PAM is the first stage of the well known M-VSB. This M-PAM scheme is much simpler and uses the channel more efficiently. The three schemes are compared and preliminary conclusions were made. Despite of several similarities, each modulation scheme has it unique merits. To determine the suitability of each scheme, more investigations and laboratory tests for all schemes are needed.

  4. Accuracy assessment of high frequency 3D ultrasound for digital impression-taking of prepared teeth

    NASA Astrophysics Data System (ADS)

    Heger, Stefan; Vollborn, Thorsten; Tinschert, Joachim; Wolfart, Stefan; Radermacher, Klaus

    2013-03-01

    Silicone based impression-taking of prepared teeth followed by plaster casting is well-established but potentially less reliable, error-prone and inefficient, particularly in combination with emerging techniques like computer aided design and manufacturing (CAD/CAM) of dental prosthesis. Intra-oral optical scanners for digital impression-taking have been introduced but until now some drawbacks still exist. Because optical waves can hardly penetrate liquids or soft-tissues, sub-gingival preparations still need to be uncovered invasively prior to scanning. High frequency ultrasound (HFUS) based micro-scanning has been recently investigated as an alternative to optical intra-oral scanning. Ultrasound is less sensitive against oral fluids and in principal able to penetrate gingiva without invasively exposing of sub-gingival preparations. Nevertheless, spatial resolution as well as digitization accuracy of an ultrasound based micro-scanning system remains a critical parameter because the ultrasound wavelength in water-like media such as gingiva is typically smaller than that of optical waves. In this contribution, the in-vitro accuracy of ultrasound based micro-scanning for tooth geometry reconstruction is being investigated and compared to its extra-oral optical counterpart. In order to increase the spatial resolution of the system, 2nd harmonic frequencies from a mechanically driven focused single element transducer were separated and corresponding 3D surface models were calculated for both fundamentals and 2nd harmonics. Measurements on phantoms, model teeth and human teeth were carried out for evaluation of spatial resolution and surface detection accuracy. Comparison of optical and ultrasound digital impression taking indicate that, in terms of accuracy, ultrasound based tooth digitization can be an alternative for optical impression-taking.

  5. The feasibility and application of gray scale adjustment method in high temperature digital image correlation

    NASA Astrophysics Data System (ADS)

    Wang, Shen; Yao, Xue Feng; Su, Yun Quan; Liu, Wei

    2017-02-01

    In this paper, the basic principle and application of linear gray scale adjustment method are investigated in high temperature digital image correlation (DIC) technology. First, the simple linear gray scale adjustment method is proposed, which can adjust the gray scale value of the saturated pixels and diminish the correlation error caused by the saturated pixels. Then, both the simulated high temperature images and DIC correlation results before and after the gray scale adjustment are provided and analyzed to verify its effectiveness, in which the displacement error decreased from 0.1 pixels to 0.04 pixels after the linear gray scale adjustment for high temperature images. Finally, the linear gray scale adjustment method is used to extract the displacement with high accuracy in high temperature experiment of SiC specimen, and the displacement error decreased from 0.5 pixels to 0.1 pixels after the linear gray scale adjustment.

  6. Design of DSP-based high-power digital solar array simulator

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Liu, Zhilong; Tong, Weichao; Feng, Jian; Ji, Yibo

    2013-12-01

    To satisfy rigid performance specifications, a feedback control was presented for zoom optical lens plants. With the increasing of global energy consumption, research of the photovoltaic(PV) systems get more and more attention. Research of the digital high-power solar array simulator provides technical support for high-power grid-connected PV systems research.This paper introduces a design scheme of the high-power digital solar array simulator based on TMS320F28335. A DC-DC full-bridge topology was used in the system's main circuit. The switching frequency of IGBT is 25kHz.Maximum output voltage is 900V. Maximum output current is 20A. Simulator can be pre-stored solar panel IV curves.The curve is composed of 128 discrete points .When the system was running, the main circuit voltage and current values was feedback to the DSP by the voltage and current sensors in real-time. Through incremental PI,DSP control the simulator in the closed-loop control system. Experimental data show that Simulator output voltage and current follow a preset solar panels IV curve. In connection with the formation of high-power inverter, the system becomes gridconnected PV system. The inverter can find the simulator's maximum power point and the output power can be stabilized at the maximum power point (MPP).

  7. Highly efficient co-removal of copper (II) and phthalic acid with self-synthesized polyamine resin.

    PubMed

    Ling, Chen; Liu, Fu-Qiang; Long, Chao; Wei, Meng-Meng; Li, Aimin

    2014-01-01

    A novel method was proposed for efficient co-removal of Cu (II) and phthalic acid (PA) using self-synthesized polyamine resin (R-NH(2)). The adsorption properties of R-NH(2) were thoroughly investigated by equilibrium, kinetic and dynamic tests in sole and binary systems at pH 5.0. The Freundlich model was a good fit for all the isotherm data, showing higher Kf values in the binary system than the sole system. The pseudo-second-order kinetic equation showed a better correlation to the experimental data in all cases and PA uptake was much faster than that of Cu (II). R-NH(2) showed highest adsorption capacities to both Cu (II) and PA among the five tested resins. Moreover, the presence of PA markedly enhanced the adsorption of Cu (II), being around 3.5 times of that of the sole system. The adsorption of PA was also slightly increased when Cu (II) was coexistent. Furthermore, using Fourier transform infrared spectrometry (FTIR) and species calculations, possible mechanisms were proposed that Cu (II) coordinated with -NH(2) and negative PA species interacted with -NH(3)(+) by electrostatic attraction. [Cu-PA] complex in the binary system possessed a much higher affinity than free Cu (II) to chelating with -NH(2), resulting in mutual enhancement.

  8. High Resolution Digital Surface Model For Production Of Airport Obstruction Charts Using Spaceborne SAR Sensors

    NASA Astrophysics Data System (ADS)

    Oliveira, Henrique; Rodrigues, Marco; Radius, Andrea

    2012-01-01

    Airport Obstruction Charts (AOCs) are graphical representations of natural or man-made obstructions (its locations and heights) around airfields, according to International Civil Aviation Organization (ICAO) Annexes 4, 14 and 15. One of the most important types of data used in AOCs production/update tasks is a Digital Surface Model (first reflective surface) of the surveyed area. The development of advanced remote sensing technologies provide the available tools for obstruction data acquisition, while Geographic Information Systems (GIS) present the perfect platform for storing and analyzing this type of data, enabling the production of digital ACOs, greatly contributing to the increase of the situational awareness of pilots and enhancing the air navigation safety level [1]. Data acquisition corresponding to the first reflective surface can be obtained through the use of Airborne Laser-Scanning and Light Detection and Ranging (ALS/LIDAR) or Spaceborne SAR Systems. The need of surveying broad areas, like the entire territory of a state, shows that Spaceborne SAR systems are the most adequate in economic and feasibility terms of the process, to perform the monitoring and producing a high resolution Digital Surface Model (DSM). The high resolution DSM generation depends on many factors: the available data set, the used technique and the setting parameters. To increase the precision and obtain high resolution products, two techniques are available using a stack of data: the PS (Permanent Scatterers) technique [2], that uses large stack of data to identify many stable and coherent targets through multi- temporal analysis, removing the atmospheric contribution and to minimize the estimation errors, and the Small Baseline Subset (SBAS) technique ([3],[4]), that relies on the use of small baseline SAR interferograms and on the application of the so called singular value decomposition (SVD) method, in order to link independent SAR acquisition data sets, separated by large

  9. Digital generation of high time-bandwidth product linear FM waveforms for radar altimeters

    NASA Astrophysics Data System (ADS)

    Griffiths, H. D.; Bradford, W. J.

    1992-04-01

    The paper describes and demonstrates a method of generating linear FM waveforms of very high time bandwidth product (in excess of 100,000) with range sidelobe levels more than adequate for future-generation radar altimeters. The technique is extremely flexible, and the pulse length and bandwidth are easily varied by changing the parameters of the digital circuitry. An analysis is developed to relate the level of phase and amplitude errors to the permissible range sidelobe level, showing that considerably greater phase errors can be tolerated than for conventional pulse compression radars. The validity of this analysis is confirmed by experiment.

  10. Digital high-pressure injection injury: the importance of early recognition and treatment

    PubMed Central

    Sarwar, Umran; Javed, Muhammad; Rahman, Shakeel; Wright, Thomas C

    2014-01-01

    High-pressure injection (HPI) injuries are an uncommon mechanism of trauma. The clinical effects of the HPI injury depend upon a number of variables including the pressures involved, chemical toxicity, quantity of material injected and its temperature. Evidence within the literature has shown that delay in identifying and treating such injuries can lead to devastating consequences. We describe one such case of a HPI injury involving engine oil to a digit. In addition, we review the clinical course, pathophysiology and management of such injuries. PMID:24554684

  11. A seamless, high-resolution digital elevation model (DEM) of the north-central California coast

    USGS Publications Warehouse

    Foxgrover, Amy C.; Barnard, Patrick L.

    2012-01-01

    A seamless, 2-meter resolution digital elevation model (DEM) of the north-central California coast has been created from the most recent high-resolution bathymetric and topographic datasets available. The DEM extends approximately 150 kilometers along the California coastline, from Half Moon Bay north to Bodega Head. Coverage extends inland to an elevation of +20 meters and offshore to at least the 3 nautical mile limit of state waters. This report describes the procedures of DEM construction, details the input data sources, and provides the DEM for download in both ESRI Arc ASCII and GeoTIFF file formats with accompanying metadata.

  12. A Comparison of the High Count Rate Performance of Three Commercially Available Digital Signal Processors

    SciTech Connect

    Dawn M. Scates; John K. Hartwell

    2005-10-01

    Three commercial ã-ray digital signal processors, a Canberra InSpector 2000, an ORTEC DigiDART, and an X-ray Instrumentation Associates Polaris system, coupled to a Canberra 2002C resistive-feedback preamplifier-equipped high-purity germanium detector, were performance tested to input rates of 440 kHz. The spectrometers were evaluated on their throughput, stability and peak shape performance. The accuracy of their quantitative corrections for dead time and pile-up were also tested. All three of the tested units performed well at input rates that strain most analog spectroscopy systems.

  13. Microearthquake monitoring at the Southeast Geysers using a high-resolution digital array

    SciTech Connect

    Kirkpatrick, A.; Peterson, J.E. Jr.; Majer, E.L.

    1995-01-01

    Microearthquake activity at the Southeast Geysers, California, geothermal field is monitored with a high-resolution digital seismic network. Hypocenters are spatially clustered in both injection and production areas, but also occur in more diffuse patterns, mostly at depths from 1 to 2.8 km. Hypocenters near the injection well DV-11 exhibit a striking correlation with movement of injectate and injectate-derived steam. Preliminary moment tensor results show promise to provide information on the differing source mechanisms resulting from fluid injection and steam extraction.

  14. Microearthquake monitoring at the Southeast Geysers using a high-resolution digital array

    SciTech Connect

    Kirkpatrick, Ann; Peterson, John E., Jr.; Majer, Ernie L.

    1995-01-26

    Microearthquake activity at the Southeast Geysers, California, geothermal field is monitored with a high-resolution digital seismic network. Hypocenters are spatially clustered in both injection and production areas, but also occur in more diffuse patterns, mostly at depths from 1 to 2.8 km. Hypocenters near the injection well DV-11 exhibit a striking correlation with movement of injectate and injectate-derived steam. Preliminary moment tensor results show promise to provide information on the differing source mechanisms resulting from fluid injection and steam extraction.

  15. A highly accurate wireless digital sun sensor based on profile detecting and detector multiplexing technologies

    NASA Astrophysics Data System (ADS)

    Wei, Minsong; Xing, Fei; You, Zheng

    2017-01-01

    The advancing growth of micro- and nano-satellites requires miniaturized sun sensors which could be conveniently applied in the attitude determination subsystem. In this work, a profile detecting technology based high accurate wireless digital sun sensor was proposed, which could transform a two-dimensional image into two-linear profile output so that it can realize a high update rate under a very low power consumption. A multiple spots recovery approach with an asymmetric mask pattern design principle was introduced to fit the multiplexing image detector method for accuracy improvement of the sun sensor within a large Field of View (FOV). A FOV determination principle based on the concept of FOV region was also proposed to facilitate both sub-FOV analysis and the whole FOV determination. A RF MCU, together with solar cells, was utilized to achieve the wireless and self-powered functionality. The prototype of the sun sensor is approximately 10 times lower in size and weight compared with the conventional digital sun sensor (DSS). Test results indicated that the accuracy of the prototype was 0.01° within a cone FOV of 100°. Such an autonomous DSS could be equipped flexibly on a micro- or nano-satellite, especially for highly accurate remote sensing applications.

  16. Application of High Speed Digital Image Correlation in Rocket Engine Hot Fire Testing

    NASA Technical Reports Server (NTRS)

    Gradl, Paul R.; Schmidt, Tim

    2016-01-01

    Hot fire testing of rocket engine components and rocket engine systems is a critical aspect of the development process to understand performance, reliability and system interactions. Ground testing provides the opportunity for highly instrumented development testing to validate analytical model predictions and determine necessary design changes and process improvements. To properly obtain discrete measurements for model validation, instrumentation must survive in the highly dynamic and extreme temperature application of hot fire testing. Digital Image Correlation has been investigated and being evaluated as a technique to augment traditional instrumentation during component and engine testing providing further data for additional performance improvements and cost savings. The feasibility of digital image correlation techniques were demonstrated in subscale and full scale hotfire testing. This incorporated a pair of high speed cameras to measure three-dimensional, real-time displacements and strains installed and operated under the extreme environments present on the test stand. The development process, setup and calibrations, data collection, hotfire test data collection and post-test analysis and results are presented in this paper.

  17. Perspectives on open access high resolution digital elevation models to produce global flood hazard layers

    NASA Astrophysics Data System (ADS)

    Sampson, Christopher; Smith, Andrew; Bates, Paul; Neal, Jeffrey; Trigg, Mark

    2015-12-01

    Global flood hazard models have recently become a reality thanks to the release of open access global digital elevation models, the development of simplified and highly efficient flow algorithms, and the steady increase in computational power. In this commentary we argue that although the availability of open access global terrain data has been critical in enabling the development of such models, the relatively poor resolution and precision of these data now limit significantly our ability to estimate flood inundation and risk for the majority of the planet's surface. The difficulty of deriving an accurate 'bare-earth' terrain model due to the interaction of vegetation and urban structures with the satellite-based remote sensors means that global terrain data are often poorest in the areas where people, property (and thus vulnerability) are most concentrated. Furthermore, the current generation of open access global terrain models are over a decade old and many large floodplains, particularly those in developing countries, have undergone significant change in this time. There is therefore a pressing need for a new generation of high resolution and high vertical precision open access global digital elevation models to allow significantly improved global flood hazard models to be developed.

  18. SEMICONDUCTOR INTEGRATED CIRCUITS: A low-jitter RF PLL frequency synthesizer with high-speed mixed-signal down-scaling circuits

    NASA Astrophysics Data System (ADS)

    Lu, Tang; Zhigong, Wang; Hong, Xue; Xiaohu, He; Yong, Xu; Ling, Sun

    2010-05-01

    A low-jitter RF phase locked loop (PLL) frequency synthesizer with high-speed mixed-signal down-scaling circuits is proposed. Several techniques are proposed to reduce the design complexity and improve the performance of the mixed-signal down-scaling circuit in the PLL. An improved D-latch is proposed to increase the speed and the driving capability of the DMP in the down-scaling circuit. Through integrating the D-latch with 'OR' logic for dual-modulus operation, the delays associated with both the 'OR' and D-flip-flop (DFF) operations are reduced, and the complexity of the circuit is also decreased. The programmable frequency divider of the down-scaling circuit is realized in a new method based on deep submicron CMOS technology standard cells and a more accurate wire-load model. The charge pump in the PLL is also realized with a novel architecture to improve the current matching characteristic so as to reduce the jitter of the system. The proposed RF PLL frequency synthesizer is realized with a TSMC 0.18-μm CMOS process. The measured phase noise of the PLL frequency synthesizer output at 100 kHz offset from the center frequency is only -101.52 dBc/Hz. The circuit exhibits a low RMS jitter of 3.3 ps. The power consumption of the PLL frequency synthesizer is also as low as 36 mW at a 1.8 V power supply.

  19. High speed, multi-channel, user programmable digital data acquisition system.

    SciTech Connect

    Sabourov, Konstantin; Hennig, Wolfgang; Walby, Mark

    2013-11-18

    As applications for radiation detection become more demanding, and in turn improvements are made in the technology of radiation detection, there is a need for high speed digital detector readout electronics matching these improvements. Specifically, full control over the on-line processing resources of modern digital electronics is desirable so that researchers can develop custom algorithms for special applications.In the proposed effort, the 500 MHz digital readout electronics previously developed by our company will be redesigned to allow user access to the on-line processing resources. In Phase I, the division of online processing into vendor and user firmware sections has been studied on existing hardware. In Phase II, the hardware will be upgraded to better facilitate the division, and the firmware will be restructured into a robust vendor logic block (providing standard functions such as host I/O, on-board memory I/O, energy computation, MCA spectra, timestamps, waveform capture, run statistics, and triggering and timing) and a user logic block for custom algorithms (with templates and examples for frequently used functions). Investigating several options to divide online processing, it was determined that the most promising approach is to “partition” a single FPGA integrated circuit into a vendor and user section, which is supported in newer devices. The analog front end of the existing electronics proved suitable for most applications, in particular high rate measurements with germanium detectors. The design architecture for new electronics was developed, combining one of the new FPGA device with the analog front end.

  20. Digitizing Preservation.

    ERIC Educational Resources Information Center

    Conway, Paul

    1994-01-01

    Discussion of digital imaging technology focuses on its potential use for preservation of library materials. Topics addressed include converting microfilm to digital; the high cost of conversion from paper or microfilm; quality; indexing; database management issues; incompatibility among imaging systems; longevity; cooperative pilot projects; and…

  1. A microprocessor-based digital feeder monitor with high-impedance fault detection

    SciTech Connect

    Patterson, R.; Tyska, W.; Russell, B.D.

    1994-12-31

    The high impedance fault detection technology developed at Texas A&M University after more than a decade of research, funded in large part by the Electric Power Research Institute, has been incorporated into a comprehensive monitoring device for overhead distribution feeders. This digital feeder monitor (DFM) uses a high waveform sampling rate for the ac current and voltage inputs in conjunction with a high-performance reduced instruction set (RISC) microprocessor to obtain the frequency response required for arcing fault detection and power quality measurements. Expert system techniques are employed to assure security while maintaining dependability. The DFM is intended to be applied at a distribution substation to monitor one feeder. The DFM is packaged in a non-drawout case which fits the panel cutout for a GE IAC overcurrent relay to facilitate retrofits at the majority of sites were electromechanical overcurrent relays already exist.

  2. Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

    DOE PAGES

    An, Zhinan; Jia, Haoling; Wu, Yueying; ...

    2015-05-04

    The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

  3. On chip droplet characterization: a practical, high-sensitivity measurement of droplet impedance in digital microfluidics.

    PubMed

    Sadeghi, Saman; Ding, Huijiang; Shah, Gaurav J; Chen, Supin; Keng, Pei Yuin; Kim, Chang-Jin; van Dam, R Michael

    2012-02-21

    We demonstrate a new approach to impedance measurement on digital microfluidics chips for the purpose of simple, sensitive, and accurate volume and liquid composition measurement. Adding only a single series resistor to existing AC droplet actuation circuits, the platform is simple to implement and has negligible effect on actuation voltage. To accurately measure the complex voltage across the resistor (and hence current through the device and droplet), the designed system is based on software-implemented lock-in amplification detection of the voltage drop across the resistor which filters out noise, enabling high-resolution and low-limit signal recovery. We observe picoliter sensitivity with linear correlation of voltage to volume extending to the microliter volumes that can be handled by digital microfluidic devices. Due to the minimal hardware, the system is robust and measurements are highly repeatable. The detection technique provides both phase and magnitude information of the real-time current flowing through the droplet for a full impedance measurement. The sensitivity and resolution of this platform enables it to distinguish between various liquids which, as demonstrated in this paper, could potentially be extended to quantify solute concentrations, liquid mixtures, and presence of analytes.

  4. Digital atlas of the zebra finch (Taeniopygia guttata) brain: a high-resolution photo atlas.

    PubMed

    Karten, Harvey J; Brzozowska-Prechtl, Agnieszka; Lovell, Peter V; Tang, Daniel D; Mello, Claudio V; Wang, Haibin; Mitra, Partha P

    2013-11-01

    We describe a set of new comprehensive, high-quality, high-resolution digital images of histological sections from the brain of male zebra finches (Taeniopygia guttata) and make them publicly available through an interactive website (http://zebrafinch.brainarchitecture.org/). These images provide a basis for the production of a dimensionally accurate and detailed digital nonstereotaxic atlas. Nissl- and myelin-stained brain sections are provided in the transverse, sagittal, and horizontal planes, with the transverse plane approximating the more traditional Frankfurt plane. In addition, a separate set of brain sections in this same plane is stained for tyrosine hydroxylase, revealing the distribution of catecholaminergic neurons (dopaminergic, noradrenergic, and adrenergic) in the songbird brain. For a subset of sagittal sections we also prepared a corresponding set of drawings, defining and annotating various nuclei, fields, and fiber tracts that are visible under Nissl and myelin staining. This atlas of the zebra finch brain is expected to become an important tool for birdsong research and comparative studies of brain organization and evolution.

  5. Quantitative analysis of vocal fold vibration during register change by high-speed digital imaging system

    NASA Astrophysics Data System (ADS)

    Kumada, Masanobu; Kobayashi, Noriko; Hirose, Hajime; Tayama, Niro; Imagawa, Hiroshi; Sakakibara, Ken-Ichi; Nito, Takaharu; Kakurai, Shin'ichi; Kumada, Chieko; Wada, Mamiko; Niimi, Seiji

    2002-05-01

    The physiological study of prosody is indispensable in terms not only of the physiological interest but also of the evaluation and treatment for pathological cases of prosody. In free talk, the changes of vocal fold vibration are found frequently and these phenomena are very important prosodic events. To analyze quantitatively the vocal fold vibration at the register change as the model of prosodic event, our high-speed digital imaging system was used at a rate of 4500 images of 256-256 pixels per second. Four healthy Japanese adults (2 males and 2 females) were served as subjects. Tasks were sustained phonation containing register changes. Two major categories (Category A and B) were found in the ways of changing of vocal fold vibrations at the register change. In Category A, changes were very smooth in terms of the vocal fold vibration. In Category B, changes were not so smooth with some additional events at the register change, such as the anterior-posterior phase difference of the vibration, the abduction of the vocal folds, or the interruption of the phonation. The number of the subtypes for Category B is thought to increase if more subjects with a wider range of variety are analyzed. For the study of prosody, our high-speed digital imaging system is a very powerful tool by which physiological information can be obtained.

  6. High efficient photocatalytic selective oxidation of benzyl alcohol to benzaldehyde by solvothermal-synthesized ZnIn{sub 2}S{sub 4} microspheres under visible light irradiation

    SciTech Connect

    Chen, Zhixin; Xu, Jingjing; Ren, Zhuyun; He, Yunhui; Xiao, Guangcan

    2013-09-15

    Hexagonal ZnIn{sub 2}S{sub 4} samples have been synthesized by a solvothermal method. Their properties have been determined by X-ray diffraction, ultraviolet–visible-light diffuse reflectance spectra, field emission scanning electron microscopy, nitrogen adsorption–desorption and X-ray photoelectron spectra. These results demonstrate that ethanol solvent has significant influence on the morphology, optical and electronic nature for such marigold-like ZnIn{sub 2}S{sub 4} microspheres. The visible light photocatalytic activities of the ZnIn{sub 2}S{sub 4} have been evaluated by selective oxidation of benzyl alcohol to benzaldehyde using molecular oxygen as oxidant. The results show that 100% conversion along with >99% selectivity are reached over ZnIn{sub 2}S{sub 4} prepared in ethanol solvent under visible light irradiation (λ>420 nm) of 2 h, but only 58% conversion and 57% yield are reached over ZnIn{sub 2}S{sub 4} prepared in aqueous solvent. A possible mechanism of the high photocatalytic activity for selective oxidation of benzyl alcohol over ZnIn{sub 2}S{sub 4} is proposed and discussed. - Graphical abstract: Marigold-like ZnIn{sub 2}S{sub 4} microspheres were synthesized by a solvothermal method. The high visible photocatalytic activities of ZnIn{sub 2}S{sub 4} were evaluated by selective oxidation of benzyl alcohol to benzaldehyde under mild conditions. Display Omitted - Highlights: • Marigold-like ZnIn{sub 2}S{sub 4} microspheres were synthesized by a solvothermal method. • The solvents have a remarkably influence on the morphology and properties of samples. • It is the first time to apply ZnIn{sub 2}S{sub 4} for selective oxidation of benzyl alcohol. • ZnIn{sub 2}S{sub 4} shows high photocatalytic activity for selective oxidation of benzyl alcohol.

  7. Very High-Speed Digital Video Capability for In-Flight Use

    NASA Technical Reports Server (NTRS)

    Corda, Stephen; Tseng, Ting; Reaves, Matthew; Mauldin, Kendall; Whiteman, Donald

    2006-01-01

    digital video camera system has been qualified for use in flight on the NASA supersonic F-15B Research Testbed aircraft. This system is capable of very-high-speed color digital imaging at flight speeds up to Mach 2. The components of this system have been ruggedized and shock-mounted in the aircraft to survive the severe pressure, temperature, and vibration of the flight environment. The system includes two synchronized camera subsystems installed in fuselage-mounted camera pods (see Figure 1). Each camera subsystem comprises a camera controller/recorder unit and a camera head. The two camera subsystems are synchronized by use of an MHub(TradeMark) synchronization unit. Each camera subsystem is capable of recording at a rate up to 10,000 pictures per second (pps). A state-of-the-art complementary metal oxide/semiconductor (CMOS) sensor in the camera head has a maximum resolution of 1,280 1,024 pixels at 1,000 pps. Exposure times of the electronic shutter of the camera range from 1/200,000 of a second to full open. The recorded images are captured in a dynamic random-access memory (DRAM) and can be downloaded directly to a personal computer or saved on a compact flash memory card. In addition to the high-rate recording of images, the system can display images in real time at 30 pps. Inter Range Instrumentation Group (IRIG) time code can be inserted into the individual camera controllers or into the M-Hub unit. The video data could also be used to obtain quantitative, three-dimensional trajectory information. The first use of this system was in support of the Space Shuttle Return to Flight effort. Data were needed to help in understanding how thermally insulating foam is shed from a space shuttle external fuel tank during launch. The cameras captured images of simulated external tank debris ejected from a fixture mounted under the centerline of the F-15B aircraft. Digital video was obtained at subsonic and supersonic flight conditions, including speeds up to Mach 2

  8. High-rate dead-time corrections in a general purpose digital pulse processing system.

    PubMed

    Abbene, Leonardo; Gerardi, Gaetano

    2015-09-01

    Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2.2 Mcps. The digital system allows, after a simple parameter setting, different and sophisticated procedures for dead-time correction, traditionally implemented in complex/dedicated systems and time-consuming set-ups.

  9. High-rate dead-time corrections in a general purpose digital pulse processing system

    PubMed Central

    Abbene, Leonardo; Gerardi, Gaetano

    2015-01-01

    Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2.2 Mcps. The digital system allows, after a simple parameter setting, different and sophisticated procedures for dead-time correction, traditionally implemented in complex/dedicated systems and time-consuming set-ups. PMID:26289270

  10. NIR-green-blue high-resolution digital images for assessement of winter cover crop biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many small unmanned aerial systems use true-color digital cameras for remote sensing. For some cameras, only the red channel is sensitive to near-infrared (NIR) light; we attached a custom red-blocking filter to a digital camera to obtain NIR-green-blue digital images. One advantage of this low-co...

  11. Use of the Digital Camera To Increase Student Interest and Learning in High School Biology.

    ERIC Educational Resources Information Center

    Tatar, Denise; Robinson, Mike

    2003-01-01

    Attempts to answer two research questions: (1) Does the use of a digital camera in laboratory activities increase student learning?; and (2) Does the use of digital cameras motivate students to take a greater interest in laboratory work? Results indicate that the digital camera did increase student learning of process skills in two biology…

  12. Digital data sets that describe aquifer characteristics of the High Plains Aquifer in western Oklahoma

    USGS Publications Warehouse

    Becker, C.J.; Runkle, D.L.; Rea, Alan

    1997-01-01

    ARC/INFO export files This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the High Plains aquifer in western Oklahoma. This area encompasses the panhandle counties of Cimarron, Texas, and Beaver, and the western counties of Harper, Ellis, Woodward, Dewey, and Roger Mills. The High Plains aquifer underlies approximately 7,000 square miles of Oklahoma and is used extensively for irrigation. The High Plains aquifer is a water-table aquifer and consists predominately of the Tertiary-age Ogallala Formation and overlying Quaternary-age alluvial and terrace deposits. In some areas the aquifer is absent and the underlying Triassic, Jurassic, or Cretaceous-age rocks are exposed at the surface. These rocks are hydraulically connected with the aquifer in some areas. The High Plains aquifer is composed of interbedded sand, siltstone, clay, gravel, thin limestones, and caliche. The proportion of various lithological materials changes rapidly from place to place, but poorly sorted sand and gravel predominate. The rocks are poorly to moderately well cemented by calcium carbonate. The aquifer boundaries, hydraulic conductivity, and recharge data sets were created by extracting geologic contact lines from published digital surficial geology maps based on a scale of 1:125,000 for the panhandle counties and 1:250,000 for the western counties. The water-level elevation contours and some boundary lines were digitized from maps in a published water-level elevation map for 1980 based on a scale of 1:250,000. The hydraulic conductivity and recharge values in this report were used as input to the ground-water flow model on the High Plains aquifer. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and

  13. Test and evaluation of the HIDEC engine uptrim algorithm. [Highly Integrated Digital Electronic Control for aircraft

    NASA Technical Reports Server (NTRS)

    Ray, R. J.; Myers, L. P.

    1986-01-01

    The highly integrated digital electronic control (HIDEC) program will demonstrate and evaluate the improvements in performance and mission effectiveness that result from integrated engine-airframe control systems. Performance improvements will result from an adaptive engine stall margin mode, a highly integrated mode that uses the airplane flight conditions and the resulting inlet distortion to continuously compute engine stall margin. When there is excessive stall margin, the engine is uptrimmed for more thrust by increasing engine pressure ratio (EPR). The EPR uptrim logic has been evaluated and implemente into computer simulations. Thrust improvements over 10 percent are predicted for subsonic flight conditions. The EPR uptrim was successfully demonstrated during engine ground tests. Test results verify model predictions at the conditions tested.

  14. Use of a new high-speed digital data acquisition system in airborne ice-sounding

    USGS Publications Warehouse

    Wright, David L.; Bradley, Jerry A.; Hodge, Steven M.

    1989-01-01

    A high-speed digital data acquisition and signal averaging system for borehole, surface, and airborne radio-frequency geophysical measurements was designed and built by the US Geological Survey. The system permits signal averaging at rates high enough to achieve significant signal-to-noise enhancement in profiling, even in airborne applications. The first field use of the system took place in Greenland in 1987 for recording data on a 150 by 150-km grid centered on the summit of the Greenland ice sheet. About 6000-line km were flown and recorded using the new system. The data can be used to aid in siting a proposed scientific corehole through the ice sheet.

  15. A new linear array detector for high resolution and low dose digital radiography

    NASA Astrophysics Data System (ADS)

    Bettuzzi, Matteo; Cornacchia, Samantha; Rossi, Massimo; Paltrinieri, Enrica; Morigi, Maria Pia; Brancaccio, Rosa; Romani, Davide; Casali, Franco

    2004-01-01

    At the Department of Physics of the University of Bologna a new intensified linear array detector is under development. The core of the system is a digital intensified CCD camera, the electron bombarded charge coupled device (EBCCD). The main innovation is a coherent rectangular-to-linear fiber optics adapter coupling the 1 in. diameter photocathode of the camera with a linear 129 mm × 1.45 mm strip of Gd 2O 2S:Tb. In this way a high spatial resolution over an extended length is obtained. The detector works as an X-ray scanner by means of a high-precision translation mechanical device to inspect a 13 cm × 18 cm area. A complete characterisation of the system has been made in terms of linearity, dynamic range, modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). At last, radiographic tests on a set of samples have been made and will be presented.

  16. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    DOE PAGES

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; ...

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for themore » analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.« less

  17. Highly integrated digital engine control system on an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Burcham, F. W., Jr.; Haering, E. A., Jr.

    1984-01-01

    The Highly Integrated Digital Electronic Control (HIDEC) program will demonstrate and evaluate the improvements in performance and mission effectiveness that result from integrated engine/airframe control systems. This system is being used on the F-15 airplane. An integrated flightpath management mode and an integrated adaptive engine stall margin mode are implemented into the system. The adaptive stall margin mode is a highly integrated mode in which the airplane flight conditions, the resulting inlet distortion, and the engine stall margin are continuously computed; the excess stall margin is used to uptrim the engine for more thrust. The integrated flightpath management mode optimizes the flightpath and throttle setting to reach a desired flight condition. The increase in thrust and the improvement in airplane performance is discussed.

  18. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    SciTech Connect

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for the analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.

  19. Programmable Illumination and High-Speed, Multi-Wavelength, Confocal Microscopy Using a Digital Micromirror

    PubMed Central

    Martial, Franck P.; Hartell, Nicholas A.

    2012-01-01

    Confocal microscopy is routinely used for high-resolution fluorescence imaging of biological specimens. Most standard confocal systems scan a laser across a specimen and collect emitted light passing through a single pinhole to produce an optical section of the sample. Sequential scanning on a point-by-point basis limits the speed of image acquisition and even the fastest commercial instruments struggle to resolve the temporal dynamics of rapid cellular events such as calcium signals. Various approaches have been introduced that increase the speed of confocal imaging. Nipkov disk microscopes, for example, use arrays of pinholes or slits on a spinning disk to achieve parallel scanning which significantly increases the speed of acquisition. Here we report the development of a microscope module that utilises a digital micromirror device as a spatial light modulator to provide programmable confocal optical sectioning with a single camera, at high spatial and axial resolution at speeds limited by the frame rate of the camera. The digital micromirror acts as a solid state Nipkov disk but with the added ability to change the pinholes size and separation and to control the light intensity on a mirror-by-mirror basis. The use of an arrangement of concave and convex mirrors in the emission pathway instead of lenses overcomes the astigmatism inherent with DMD devices, increases light collection efficiency and ensures image collection is achromatic so that images are perfectly aligned at different wavelengths. Combined with non-laser light sources, this allows low cost, high-speed, multi-wavelength image acquisition without the need for complex wavelength-dependent image alignment. The micromirror can also be used for programmable illumination allowing spatially defined photoactivation of fluorescent proteins. We demonstrate the use of this system for high-speed calcium imaging using both a single wavelength calcium indicator and a genetically encoded, ratiometric, calcium

  20. High resolution digital soil mapping as a future instrument for developing sustainable landuse strategies

    NASA Astrophysics Data System (ADS)

    Gries, Philipp; Funke, Lisa-Marie; Baumann, Frank; Schmidt, Karsten; Behrens, Thorsten; Scholten, Thomas

    2016-04-01

    Climate change, increase in population and intensification of land use pose a great challenge for sustainable handling of soils. Intelligent landuse systems are able to minimize and/or avoid soil erosion and loss of soil fertility. A successful application of such systems requires area-wide soil information with high resolution. Containing three consecutive steps, the project INE-2-H („innovative sustainable landuse") at the University of Tuebingen is about creating high-resolution soil information using Digital Soil Mapping (DSM) techniques to develop sustainable landuse strategies. Input data includes soil data from fieldwork (texture and carbon content), the official digital soil and geological map (1:50.000) as well as a wide selection of local, complex and combined terrain parameters. First, soil maps have been created using the DSM approach and Random Forest (RF). Due to high resolution (10x10 m pixels), those maps show a more detailed spatial variability of soil information compared to the official maps used. Root mean square errors (RMSE) of the modelled maps vary from 2.11 % to 6.87 % and the coefficients of determination (R²) go from 0.42 to 0.68. Second, soil erosion potentials have been estimated according to the Universal Soil Loss Equation (USLE). Long-term average annual soil loss ranges from 0.56 to 24.23 [t/ha/a]. Third, combining high-resolution erosion potentials with expert-knowledge of local farmers will result in a landuse system adapted to local conditions. This system will include sustainable strategies reducing soil erosion and conserving soil fertility.

  1. High-resolution digital brain atlases: a Hubble telescope for the brain.

    PubMed

    Jones, Edward G; Stone, James M; Karten, Harvey J

    2011-05-01

    We describe implementation of a method for digitizing at microscopic resolution brain tissue sections containing normal and experimental data and for making the content readily accessible online. Web-accessible brain atlases and virtual microscopes for online examination can be developed using existing computer and internet technologies. Resulting databases, made up of hierarchically organized, multiresolution images, enable rapid, seamless navigation through the vast image datasets generated by high-resolution scanning. Tools for visualization and annotation of virtual microscope slides enable remote and universal data sharing. Interactive visualization of a complete series of brain sections digitized at subneuronal levels of resolution offers fine grain and large-scale localization and quantification of many aspects of neural organization and structure. The method is straightforward and replicable; it can increase accessibility and facilitate sharing of neuroanatomical data. It provides an opportunity for capturing and preserving irreplaceable, archival neurohistological collections and making them available to all scientists in perpetuity, if resources could be obtained from hitherto uninterested agencies of scientific support.

  2. Robust content-dependent high-fidelity watermark for tracking in digital cinema

    NASA Astrophysics Data System (ADS)

    Lubin, Jeffrey; Bloom, Jeffrey A.; Cheng, Hui

    2003-06-01

    Forensic digital watermarking is a promising tool in the fight against piracy of copyrighted motion imagery content, but to be effective it must be (1) imperceptibly embedded in high-definition motion picture source, (2) reliably retrieved, even from degraded copies as might result from camcorder capture and subsequent very-low-bitrate compression and distribution on the Internet, and (3) secure against unauthorized removal. No existing watermarking technology has yet to meet these three simultaneous requirements of fidelity, robustness, and security. We describe here a forensic watermarking approach that meets all three requirements. It is based on the inherent robustness and imperceptibility of very low spatiotemporal frequency watermark carriers, and on a watermark placement technique that renders jamming attacks too costly in picture quality, even if the attacker has complete knowledge of the embedding algorithm. The algorithm has been tested on HD Cinemascope source material exhibited in a digital cinema viewing room. The watermark is imperceptible, yet recoverable after exhibition capture with camcorders, and after the introduction of other distortions such as low-pass filtering, noise addition, geometric shifts, and the manipulation of brightness and contrast.

  3. High-contrast multilayer imaging of biological organisms through dark-field digital refocusing

    NASA Astrophysics Data System (ADS)

    Faridian, Ahmad; Pedrini, Giancarlo; Osten, Wolfgang

    2013-08-01

    We have developed an imaging system to extract high contrast images from different layers of biological organisms. Utilizing a digital holographic approach, the system works without scanning through layers of the specimen. In dark-field illumination, scattered light has the main contribution in image formation, but in the case of coherent illumination, this creates a strong speckle noise that reduces the image quality. To remove this restriction, the specimen has been illuminated with various speckle-fields and a hologram has been recorded for each speckle-field. Each hologram has been analyzed separately and the corresponding intensity image has been reconstructed. The final image has been derived by averaging over the reconstructed images. A correlation approach has been utilized to determine the number of speckle-fields required to achieve a desired contrast and image quality. The reconstructed intensity images in different object layers are shown for different sea urchin larvae. Two multimedia files are attached to illustrate the process of digital focusing.

  4. Targeted enrichment and high-resolution digital profiling of mitochondrial DNA deletions in human brain.

    PubMed

    Taylor, Sean D; Ericson, Nolan G; Burton, Joshua N; Prolla, Tomas A; Silber, John R; Shendure, Jay; Bielas, Jason H

    2014-02-01

    Due largely to the inability to accurately quantify and characterize de novo deletion events, the mechanisms underpinning the pathogenic expansion of mtDNA deletions in aging and neuromuscular disorders remain poorly understood. Here, we outline and validate a new tool termed 'Digital Deletion Detection' (3D) that allows for high-resolution analysis of rare deletions occurring at frequencies as low as 1 × 10(-8) . 3D is a three-step process that includes targeted enrichment for deletion-bearing molecules, single-molecule partitioning of genomes into thousands of droplets for direct quantification via droplet digital PCR, and breakpoint characterization using massively parallel sequencing. Using 3D, we interrogated over 8 billion mitochondrial genomes to analyze the age-related dynamics of mtDNA deletions in human brain tissue. We demonstrate that the total deletion load increases with age, while the total number and diversity of unique deletions remain constant. Our data provide support for the hypothesis that expansion of pre-existing mutations is the primary factor contributing to age-related accumulation of mtDNA deletions.

  5. Massively parallel digital high resolution melt for rapid and absolutely quantitative sequence profiling

    PubMed Central

    Velez, Daniel Ortiz; Mack, Hannah; Jupe, Julietta; Hawker, Sinead; Kulkarni, Ninad; Hedayatnia, Behnam; Zhang, Yang; Lawrence, Shelley; Fraley, Stephanie I.

    2017-01-01

    In clinical diagnostics and pathogen detection, profiling of complex samples for low-level genotypes represents a significant challenge. Advances in speed, sensitivity, and extent of multiplexing of molecular pathogen detection assays are needed to improve patient care. We report the development of an integrated platform enabling the identification of bacterial pathogen DNA sequences in complex samples in less than four hours. The system incorporates a microfluidic chip and instrumentation to accomplish universal PCR amplification, High Resolution Melting (HRM), and machine learning within 20,000 picoliter scale reactions, simultaneously. Clinically relevant concentrations of bacterial DNA molecules are separated by digitization across 20,000 reactions and amplified with universal primers targeting the bacterial 16S gene. Amplification is followed by HRM sequence fingerprinting in all reactions, simultaneously. The resulting bacteria-specific melt curves are identified by Support Vector Machine learning, and individual pathogen loads are quantified. The platform reduces reaction volumes by 99.995% and achieves a greater than 200-fold increase in dynamic range of detection compared to traditional PCR HRM approaches. Type I and II error rates are reduced by 99% and 100% respectively, compared to intercalating dye-based digital PCR (dPCR) methods. This technology could impact a number of quantitative profiling applications, especially infectious disease diagnostics. PMID:28176860

  6. High-speed video imaging and digital analysis of microscopic features in contracting striated muscle cells

    NASA Astrophysics Data System (ADS)

    Roos, Kenneth P.; Taylor, Stuart R.

    1993-02-01

    The rapid motion of microscopic features such as the cross striations of single contracting muscle cells are difficult to capture with conventional optical microscopes, video systems, and image processing approaches. An integrated digital video imaging microscope system specifically designed to capture images from single contracting muscle cells at speeds of up to 240 Hz and to analyze images to extract features critical for the understanding of muscle contraction is described. This system consists of a brightfield microscope with immersion optics coupled to a high-speed charge-coupled device (CCD) video camera, super-VHS (S- VHS) and optical media disk video recording (OMDR) systems, and a semiautomated digital image analysis system. Components are modified to optimize spatial and temporal resolution to permit the evaluation of submicrometer features in real physiological time. This approach permits the critical evaluation of the magnitude, time course, and uniformity of contractile function throughout the volume of a single living cell with higher temporal and spatial resolutions than previously possible.

  7. Design of high-resolution digital microscope eyepiece based on FPGA

    NASA Astrophysics Data System (ADS)

    Cai, Jin; Chen, Enguo; Liu, Peng; Yu, Feihong

    2012-10-01

    The paper presents a low-cost and portable digital microscope eyepiece based on Field Programmable gate Array (FPGA). A 1.3 million pixels CMOS (Complementary Metal Oxide Semiconductor) sensor is used as the imaging sensor. To get higher performance, the image pre-processing is completed on hardware. After that, image data are transmitted into frame buffer through transmission channel constructed by FIFO and DMA controller. The display controller gets the data from the frame buffer and sends them to the DVI/HDMI transmitter to encode the data by TMDS. All the control logic is realized inside one EP2C20 FPGA chip based on SoPC (System on a Programmable Chip) Framework and Nios II processer core is considered as the control center. The design makes full use of FPGA parallel and pipeline processing technology to achieve the hardware and software co-design, which complete high-resolution image acquisition, caching and display. The maximum resolution of real-time preview could reach SXGA (1280 x 1024) with the frame rate up to 15 fps. The system also integrates SD card interface, which captures the BMP format file into the SD (Security Digital) card.

  8. A miniature high-efficiency fully digital adaptive voltage scaling buck converter

    NASA Astrophysics Data System (ADS)

    Li, Hangbiao; Zhang, Bo; Luo, Ping; Zhen, Shaowei; Liao, Pengfei; He, Yajuan; Li, Zhaoji

    2015-09-01

    A miniature high-efficiency fully digital adaptive voltage scaling (AVS) buck converter is proposed in this paper. The pulse skip modulation with flexible duty cycle (FD-PSM) is used in the AVS controller, which simplifies the circuit architecture (<170 gates) and greatly saves the die area and the power consumption. The converter is implemented in a 0.13-μm one-poly-eight-metal (1P8 M) complementary metal oxide semiconductor process and the active on-chip area of the controller is only 0.003 mm2, which is much smaller. The measurement results show that when the operating frequency of the digital load scales dynamically from 25.6 MHz to 112.6 MHz, the supply voltage of which can be scaled adaptively from 0.84 V to 1.95 V. The controller dissipates only 17.2 μW, while the supply voltage of the load is 1 V and the operating frequency is 40 MHz.

  9. Massively parallel digital high resolution melt for rapid and absolutely quantitative sequence profiling

    NASA Astrophysics Data System (ADS)

    Velez, Daniel Ortiz; Mack, Hannah; Jupe, Julietta; Hawker, Sinead; Kulkarni, Ninad; Hedayatnia, Behnam; Zhang, Yang; Lawrence, Shelley; Fraley, Stephanie I.

    2017-02-01

    In clinical diagnostics and pathogen detection, profiling of complex samples for low-level genotypes represents a significant challenge. Advances in speed, sensitivity, and extent of multiplexing of molecular pathogen detection assays are needed to improve patient care. We report the development of an integrated platform enabling the identification of bacterial pathogen DNA sequences in complex samples in less than four hours. The system incorporates a microfluidic chip and instrumentation to accomplish universal PCR amplification, High Resolution Melting (HRM), and machine learning within 20,000 picoliter scale reactions, simultaneously. Clinically relevant concentrations of bacterial DNA molecules are separated by digitization across 20,000 reactions and amplified with universal primers targeting the bacterial 16S gene. Amplification is followed by HRM sequence fingerprinting in all reactions, simultaneously. The resulting bacteria-specific melt curves are identified by Support Vector Machine learning, and individual pathogen loads are quantified. The platform reduces reaction volumes by 99.995% and achieves a greater than 200-fold increase in dynamic range of detection compared to traditional PCR HRM approaches. Type I and II error rates are reduced by 99% and 100% respectively, compared to intercalating dye-based digital PCR (dPCR) methods. This technology could impact a number of quantitative profiling applications, especially infectious disease diagnostics.

  10. Massively parallel digital high resolution melt for rapid and absolutely quantitative sequence profiling.

    PubMed

    Velez, Daniel Ortiz; Mack, Hannah; Jupe, Julietta; Hawker, Sinead; Kulkarni, Ninad; Hedayatnia, Behnam; Zhang, Yang; Lawrence, Shelley; Fraley, Stephanie I

    2017-02-08

    In clinical diagnostics and pathogen detection, profiling of complex samples for low-level genotypes represents a significant challenge. Advances in speed, sensitivity, and extent of multiplexing of molecular pathogen detection assays are needed to improve patient care. We report the development of an integrated platform enabling the identification of bacterial pathogen DNA sequences in complex samples in less than four hours. The system incorporates a microfluidic chip and instrumentation to accomplish universal PCR amplification, High Resolution Melting (HRM), and machine learning within 20,000 picoliter scale reactions, simultaneously. Clinically relevant concentrations of bacterial DNA molecules are separated by digitization across 20,000 reactions and amplified with universal primers targeting the bacterial 16S gene. Amplification is followed by HRM sequence fingerprinting in all reactions, simultaneously. The resulting bacteria-specific melt curves are identified by Support Vector Machine learning, and individual pathogen loads are quantified. The platform reduces reaction volumes by 99.995% and achieves a greater than 200-fold increase in dynamic range of detection compared to traditional PCR HRM approaches. Type I and II error rates are reduced by 99% and 100% respectively, compared to intercalating dye-based digital PCR (dPCR) methods. This technology could impact a number of quantitative profiling applications, especially infectious disease diagnostics.

  11. Processing of multi-digit additions in high math-anxious individuals: psychophysiological evidence

    PubMed Central

    Núñez-Peña, María Isabel; Suárez-Pellicioni, Macarena

    2015-01-01

    We investigated the time course of neural processing of multi-digit additions in high- (HMA) and low-math anxious (LMA) individuals. Seventeen HMA and 17 LMA individuals were presented with two-digit additions and were asked to perform a verification task. Behavioral data showed that HMA individuals were slower and more error prone than their LMA peers, and that incorrect solutions were solved more slowly and less accurately than correct ones. Moreover, HMA individuals tended to need more time and commit more errors when having to verify incorrect solutions than correct ones. ERPs time-locked to the presentation of the addends (calculation phase) and to the presentation of the proposed solution (verification phase) were also analyzed. In both phases, a P2 component of larger amplitude was found for HMA individuals than for their LMA peers. Because the P2 component is considered to be a biomarker of the mobilization of attentional resources toward emotionally negative stimuli, these results suggest that HMA individuals may have invested more attentional resources both when processing the addends (calculation phase) and when they had to report whether the proposed solution was correct or not (verification phase), as compared to their LMA peers. Moreover, in the verification phase, LMA individuals showed a larger late positive component (LPC) for incorrect solutions at parietal electrodes than their HMA counterparts. The smaller LPC shown by HMA individuals when verifying incorrect solutions suggests that these solutions may have been appeared more plausible to them than to their LMA counterparts. PMID:26347705

  12. A highly stable mm-wave synthesizer realized by mixing two lasers locked to an optical frequency comb generator

    NASA Astrophysics Data System (ADS)

    Musha, Mitsuru; Ueda, Akitoshi; Horikoshi, Munekazu; Nakagawa, Ken'ichi; Ishiguro, Masato; Ueda, Ken-ichi; Ito, Hiroshi

    2004-10-01

    Millimeter signal generation with high spectral purity and low phase fluctuations up to 100 GHz were demonstrated with an optical method in which two external-cavity laser diodes were phase-locked to an electro-optic modulator (EOM)-based optical frequency comb generator (OFCG). The additional phase noise caused from the cavity fluctuation in OFCG was completely canceled, and the phase noise of the heterodyne beat note of two LDs was determined only by that of the signal generator below offset frequency of 10 kHz. The detailed investigation of such a high frequency signal had never been done before, and the measured frequency of 100 GHz was limited only by the bandwidth of the phase noise detection system, and can be expanded up to more than 1 THz.

  13. Super-high-frequency shielding properties of excimer-laser-synthesized-single-wall-carbon-nanotubes/polyurethane nanocomposite films

    NASA Astrophysics Data System (ADS)

    Aïssa, B.; Laberge, L. L.; Habib, M. A.; Denidni, T. A.; Therriault, D.; El Khakani, M. A.

    2011-04-01

    Electromagnetic shielding attenuation (ESA) properties of carbon nanotubes/polymer nanocomposite films, in the super high frequency (SHF) X-band (7-12 GHz) domain are studied. The nanocomposite films consisted of thermoset polyurethane (PU) resin blended with single-walled carbon nanotubes (SWCNTs) mats, and deposited on fused quartz substrates. Two different approaches were used to achieve the nanocomposite films, namely (i) through the on-substrate "all-laser" growth approach of SWCNTs directly onto substrate, followed by their infiltration by the PU resin, and (ii) by appropriately dispersing the chemically-purified SWCNTs (in the soot form) into the PU matrix and their subsequent deposition onto quartz substrates by means of a solvent casting process. Characterizations of the ESA properties of the developed nanocomposite films show that they exhibit systematically a deep shielding band, centered at around 9.5 GHz, with an attenuation as high as |- 30| dB, recorded for SWCNT loads of 2.5 wt. % and above. A direct correlation is established between the electrical conductivity of the nanocomposite films and their electromagnetic shielding capacity. The SWCNTs/PU nanocomposites developed here are highly promising shielding materials as SHF notch filters, as their ESA capacity largely exceeds the target value of |- 20| dB generally requested for commercial applications.

  14. Super-high-frequency shielding properties of excimer-laser-synthesized-single-wall-carbon-nanotubes/polyurethane nanocomposite films

    SciTech Connect

    Aiessa, B.; Habib, M. A.; Denidni, T. A.; El Khakani, M. A.; Laberge, L. L.; Therriault, D.

    2011-04-15

    Electromagnetic shielding attenuation (ESA) properties of carbon nanotubes/polymer nanocomposite films, in the super high frequency (SHF) X-band (7-12 GHz) domain are studied. The nanocomposite films consisted of thermoset polyurethane (PU) resin blended with single-walled carbon nanotubes (SWCNTs) mats, and deposited on fused quartz substrates. Two different approaches were used to achieve the nanocomposite films, namely (i) through the on-substrate ''all-laser'' growth approach of SWCNTs directly onto substrate, followed by their infiltration by the PU resin, and (ii) by appropriately dispersing the chemically-purified SWCNTs (in the soot form) into the PU matrix and their subsequent deposition onto quartz substrates by means of a solvent casting process. Characterizations of the ESA properties of the developed nanocomposite films show that they exhibit systematically a deep shielding band, centered at around 9.5 GHz, with an attenuation as high as |- 30| dB, recorded for SWCNT loads of 2.5 wt. % and above. A direct correlation is established between the electrical conductivity of the nanocomposite films and their electromagnetic shielding capacity. The SWCNTs/PU nanocomposites developed here are highly promising shielding materials as SHF notch filters, as their ESA capacity largely exceeds the target value of |- 20| dB generally requested for commercial applications.

  15. The research of digital circuit system for high accuracy CCD of portable Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Yin, Yu; Cui, Yongsheng; Zhang, Xiuda; Yan, Huimin

    2013-08-01

    The Raman spectrum technology is widely used for it can identify various types of molecular structure and material. The portable Raman spectrometer has become a hot direction of the spectrometer development nowadays for its convenience in handheld operation and real-time detection which is superior to traditional Raman spectrometer with heavy weight and bulky size. But there is still a gap for its measurement sensitivity between portable and traditional devices. However, portable Raman Spectrometer with Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) technology can enhance the Raman signal significantly by several orders of magnitude, giving consideration in both measurement sensitivity and mobility. This paper proposed a design and implementation of driver and digital circuit for high accuracy CCD sensor, which is core part of portable spectrometer. The main target of the whole design is to reduce the dark current generation rate and increase signal sensitivity during the long integration time, and in the weak signal environment. In this case, we use back-thinned CCD image sensor from Hamamatsu Corporation with high sensitivity, low noise and large dynamic range. In order to maximize this CCD sensor's performance and minimize the whole size of the device simultaneously to achieve the project indicators, we delicately designed a peripheral circuit for the CCD sensor. The design is mainly composed with multi-voltage circuit, sequential generation circuit, driving circuit and A/D transition parts. As the most important power supply circuit, the multi-voltage circuits with 12 independent voltages are designed with reference power supply IC and set to specified voltage value by the amplifier making up the low-pass filter, which allows the user to obtain a highly stable and accurate voltage with low noise. What's more, to make our design easy to debug, CPLD is selected to generate sequential signal. The A/D converter chip consists of a correlated

  16. Nanocrystalline Nd2Fe17 synthesized by high-energy ball milling: crystal structure, microstructure and magnetic properties.

    PubMed

    Álvarez, Pablo; Gorria, Pedro; Franco, Victorino; Sánchez Marcos, Jorge; Pérez, María J; Sánchez Llamazares, José L; Puente Orench, Inés; Blanco, Jesús A

    2010-06-02

    Nanocrystalline Nd(2)Fe(17) powders have been obtained by means of high-energy ball milling from nearly single-phase bulk alloys produced by arc melting and high temperature homogenization annealing. The rhombohedral Th(2)Zn(17)-type crystal structure of the bulk alloy remains unaltered after the milling process, with almost unchanged values for the cell parameters. However, the severe mechanical processing induces drastic microstructural changes. A decrease of the mean crystalline size down to around 10 nm is observed, giving rise to a considerable augmentation of the disordered inter-grain boundaries. This modification of the microstructure affects the magnetic behaviour of the milled powders, although the magnetic structure remains collinear ferromagnetic. While a unique ferro-to-paramagnetic transition temperature, T(C) = 339 ± 2 K, is observed in the bulk alloy, the nanocrystalline samples exhibit a more likely distribution of T(C) values. The latter seems to be responsible for the significant broadening of the temperature range in which magneto-caloric effect is observed, and the lowering of the maximum value of the magnetic entropy change.

  17. Unusual magnetic structure of the high-pressure synthesized perovskites A CrO3 (A =Sc , In, Tl)

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Manuel, Pascal; Khalyavin, Dmitry D.; Orlandi, Fabio; Kumagai, Yu; Oba, Fumiyasu; Yi, Wei; Belik, Alexei A.

    2017-02-01

    Magnetic structures of metastable perovskites ScCrO3, InCrO3, and TlCrO3, stabilized under high-pressure and high-temperature conditions, have been studied by neutron powder diffraction. Similar to the other orthochromites LnCrO3 (Ln = lanthanide or Y), these materials crystallize into the orthorhombic structure with P n m a 1' symmetry. The spin configuration of the metastable perovskites has been found to be C type, contrasting with the G -type structure usually observed in LnCrO3. First-principles calculations demonstrate that the C -type structure found in ScCrO3 and InCrO3 is attributed to a ferromagnetic (FM) nearest-neighbor interaction, while in TlCrO3, this type of magnetic ordering is stabilized by a strong next-nearest-neighbor antiferromagnetic (AFM) exchange. The spins in the C -type magnetic structure line up along the orthorhombic b axis, yielding the P n m a magnetic symmetry. The dominant mechanism controlling this spin direction has been concluded to be the single ion anisotropy imposed by a uniaxial distortion of CrO6 octahedra.

  18. Low-temperature rapid syntheses of high-quality ZnO nanostructure arrays induced by ammonium salt

    NASA Astrophysics Data System (ADS)

    Zhao, Ying; Tang, Yang; Han, Zhihua

    2017-01-01

    We have developed a simple ammonium ion-assisted hydrothermal method for the fast preparation of high quality Zinc Oxide (ZnO) nanorod arrays. Ammonium salts were introduced into typically hydrothermal growth solutions formed from Zinc acetate (ZnAc2) and hexamethylenetetramine (HMTA). Scanning electron microscope (SEM), X-ray diffractometer (XRD), High resolution transmission electron microscopic (HRTEM) and photoluminescence (PL) measurements revealed that the growth rate of ZnO nanorods was promoted by adding ammonium salts and the as-grown ZnO nanostructure arrays showed remarkably low defect density. Upon addition of ammonium salt to the hydrothermal reaction solution, complex Zn(NH3)42+ was formed by Zn2+ capturing NH3 molecules dissociated from HMTA. The improvement of growth rate and optical property of the ZnO nanostructure arrays was attributed to positively charged Zn(NH3)42+ attracting oxygen rich OH- in the growth sites of ZnO for hydrolysis reaction and simultaneously inhibiting the defect. Our results demonstrated that ammonium salt can act as a new paradigm to control morphology and quality of the ZnO microstructures.

  19. Explaining Synthesized Software

    NASA Technical Reports Server (NTRS)

    VanBaalen, Jeffrey; Robinson, Peter; Lowry, Michael; Pressburger, Thomas; Lau, Sonie (Technical Monitor)

    1998-01-01

    Motivated by NASA's need for high-assurance software, NASA Ames' Amphion project has developed a generic program generation system based on deductive synthesis. Amphion has a number of advantages, such as the ability to develop a new synthesis system simply by writing a declarative domain theory. However, as a practical matter, the validation of the domain theory for such a system is problematic because the link between generated programs and the domain theory is complex. As a result, when generated programs do not behave as expected, it is difficult to isolate the cause, whether it be an incorrect problem specification or an error in the domain theory. This paper describes a tool we are developing that provides formal traceability between specifications and generated code for deductive synthesis systems. It is based on extensive instrumentation of the refutation-based theorem prover used to synthesize programs. It takes augmented proof structures and abstracts them to provide explanations of the relation between a specification, a domain theory, and synthesized code. In generating these explanations, the tool exploits the structure of Amphion domain theories, so the end user is not confronted with the intricacies of raw proof traces. This tool is crucial for the validation of domain theories as well as being important in everyday use of the code synthesis system. It plays an important role in validation because when generated programs exhibit incorrect behavior, it provides the links that can be traced to identify errors in specifications or domain theory. It plays an important role in the everyday use of the synthesis system by explaining to users what parts of a specification or of the domain theory contribute to what pieces of a generated program. Comments are inserted into the synthesized code that document these explanations.

  20. Synthesizing high-order harmonics to generate a sub-cycle pulse in free-electron lasers

    NASA Astrophysics Data System (ADS)

    Kida, Yuichiro; Kinjo, Ryota; Tanaka, Takashi

    2016-10-01

    An approach is proposed to generate a quasi-isolated sub-cycle pulse in X-ray free-electron lasers. Its principle is based on the recently proposed concept of mono-cycle harmonic generation [T. Tanaka, Phys. Rev. Lett. 114, 044801 (2015)], but uses the chirped microbunch with high-order harmonic frequencies. This allows the synthesis of a sub-cycle field structure in the coherent radiation. Moreover, the tolerance in energy spread is greatly relaxed compared with the originally proposed scheme. Additionally, the practical procedure for realizing the scheme is greatly simplified. Numerical investigations show that a quasi-isolated sub-cycle pulse with a gigawatt peak power can be generated using an electron beam with a realistic energy spread as conventional accelerators for free-electron lasers.

  1. An alkaline one-pot reaction to synthesize luminescent Eu-BTC MOF nanorods, highly pure and water-insoluble, under room conditions

    NASA Astrophysics Data System (ADS)

    Medina-Velazquez, D. Y.; Alejandre-Zuniga, B. Y.; Loera-Serna, S.; Ortiz, E. M.; Morales-Ramirez, A. de J.; Garfias-Garcia, E.; Garcia-Murillo, A.; Falcony, C.

    2016-12-01

    The increasing demand for optoelectronic devices requires the development of luminescent materials with high luminescence efficiency and low energy demands, and the metalorganic frameworks (MOFs) with lanthanides ions offer great potential in this area. The metalorganic materials provide properties of flexibility, low density, low-cost methods of synthesis, and insolubility in water, which gives them an advantage over traditional phosphors. In this study, a benzenetricarboxylate ligand (BTC) with a Eu3+ MOF was synthesized, and its structural and luminescent properties were measured. The metalorganic compound was generated in a one-pot reaction from europium nitrate and trimesic acid precursors. Through characterization by X-ray diffraction powder, infrared spectroscopy, SEM structural characterization, and luminescent spectroscopy, the formation of Europium benzenetricarboxylate (Eu-BTC) MOF nanorods was tested and the calculated value was in the range of 30-60 nm. A red luminescent emission with high intensity was observed for all the procedures.

  2. Generation of Bright, Spatially Coherent Soft X-Ray High Harmonics in a Hollow Waveguide Using Two-Color Synthesized Laser Pulses

    NASA Astrophysics Data System (ADS)

    Jin, Cheng; Stein, Gregory J.; Hong, Kyung-Han; Lin, C. D.

    2015-07-01

    We investigate the efficient generation of low-divergence high-order harmonics driven by waveform-optimized laser pulses in a gas-filled hollow waveguide. The drive waveform is obtained by synthesizing two-color laser pulses, optimized such that highest harmonic yields are emitted from each atom. Optimization of the gas pressure and waveguide configuration has enabled us to produce bright and spatially coherent harmonics extending from the extreme ultraviolet to soft x rays. Our study on the interplay among waveguide mode, atomic dispersion, and plasma effect uncovers how dynamic phase matching is accomplished and how an optimized waveform is maintained when optimal waveguide parameters (radius and length) and gas pressure are identified. Our analysis should help laboratory development in the generation of high-flux bright coherent soft x rays as tabletop light sources for applications.

  3. Efficient Automated Syntheses of High Specific Activity 6-[18F]Fluorodopamine Using A Diaryliodonium Salt Precursor

    PubMed Central

    Neumann, Kiel D.; Qin, Linlin; Vāvere, Amy L.; Shen, Bin; Miao, Zheng; Chin, Frederick T.; Shulkin, Barry L.; Snyder, Scott E.; DiMagno, Stephen G.

    2015-01-01

    6-[18F]Fluorodopamine, 6-[18F]F-DA, is a PET radiopharmaceutical used to image sympathetic cardiac innervation and neuroendocrine tumors. Imaging with 6-[18F]F-DA is constrained, in part, by the bioactivity and neurotoxicity of 6-[19F]fluorodopamine. Furthermore, routine access to this radiotracer is limited by the inherent difficulty of incorporation of [18F]fluoride into electron-rich aromatic substrates. We describe the simple and direct preparation of high specific activity (SA) 6-[18F]F-DA from no-carrier-added (n.c.a.) [18F]fluoride. Incorporation of n.c.a. [18F]fluoride into a diaryliodonium salt precursor was achieved in 50–75% radiochemical yields (decay-corrected to EOB). Synthesis of 6-[18F]F-DA on the IBA Synthera® and GE TRACERlab FX-FN automated platforms gave 6-[18F]F-DA in >99% chemical and radiochemical purities after HPLC purification. The final non-corrected yields of 6-[18F]F-DA were 25 ± 4% (n = 4, 65 min) and 31 ± 6% (n = 3, 75 min) using the Synthera and TRACERlab modules, respectively. Efficient access to high SA 6-[18F]F-DA from a diaryliodonium salt precursor and n.c.a. [18F]fluoride is provided by a relatively subtle change in reaction conditions; replacement of a polar aprotic solvent (acetonitrile) with a relatively nonpolar solvent (toluene) during the critical radiofluorination reaction. Implementation of this process on common radiochemistry platforms should make 6-[18F]fluorodopamine readily available to the wider imaging community. PMID:26695865

  4. Albumin is synthesized in epididymis and aggregates in a high molecular mass glycoprotein complex involved in sperm-egg fertilization.

    PubMed

    Arroteia, Kélen Fabíola; Barbieri, Mainara Ferreira; Souza, Gustavo Henrique Martins Ferreira; Tanaka, Hiromitsu; Eberlin, Marcos Nogueira; Hyslop, Stephen; Alvares, Lúcia Elvira; Pereira, Luís Antonio Violin Dias

    2014-01-01

    The epididymis has an important role in the maturation of sperm for fertilization, but little is known about the epididymal molecules involved in sperm modifications during this process. We have previously described the expression pattern for an antigen in epididymal epithelial cells that reacts with the monoclonal antibody (mAb) TRA 54. Immunohistochemical and immunoblotting analyses suggest that the epitope of the epididymal antigen probably involves a sugar moiety that is released into the epididymal lumen in an androgen-dependent manner and subsequently binds to luminal sperm. Using column chromatography, SDS-PAGE with in situ digestion and mass spectrometry, we have identified the protein recognized by mAb TRA 54 in mouse epididymal epithelial cells. The ∼65 kDa protein is part of a high molecular mass complex (∼260 kDa) that is also present in the sperm acrosomal vesicle and is completely released after the acrosomal reaction. The amino acid sequence of the protein corresponded to that of albumin. Immunoprecipitates with anti-albumin antibody contained the antigen recognized by mAb TRA 54, indicating that the epididymal molecule recognized by mAb TRA 54 is albumin. RT-PCR detected albumin mRNA in the epididymis and fertilization assays in vitro showed that the glycoprotein complex containing albumin was involved in the ability of sperm to recognize and penetrate the egg zona pellucida. Together, these results indicate that epididymal-derived albumin participates in the formation of a high molecular mass glycoprotein complex that has an important role in egg fertilization.

  5. Technical and investigative support for high density digital satellite recording systems

    NASA Technical Reports Server (NTRS)

    Schultz, R. A.

    1982-01-01

    Methods and results of examinations and tests conducted on magnetic recording tapes under consideration for a high density digital (HDDR) satellite recording system are described. The examinations and tests investigate the performance of tapes with respect to their physical, magnetic and electrical characteristics. The objective of the tests, the likely significance of typical results, and the importance of the characteristics under investigation to the application are included. Theoretical discussions of measurement methods are provided where appropriate. Methods and results are discussed; the results of some sections are tabulated together to facilitate their comparison. The conclusion of each test section relates the test results to their possible significance and attempts to correlate the results of that section with the results of other tests. Some of the sections analyze sources of error inherent in the measurement methods or relate the value of the information obtained to the objectives of the test or the overall purpose of the project.

  6. Performance improvements of a highly integrated digital electronic control system for an F-15 airplane

    NASA Technical Reports Server (NTRS)

    Putnam, T. W.; Burcham, F. W., Jr.; Andries, M. G.; Kelly, J. B.

    1985-01-01

    The NASA highly integrated digital electronic control (HIDEC) program is structured to conduct flight research into the benefits of integrating an aircraft flight control system with the engine control system. A brief description of the HIDEC system installed on an F-15 aircraft is provided. The adaptive engine control system (ADECS) mode is described in detail, together with simulation results and analyses that show the significant excess thrust improvements achievable with the ADECS mode. It was found that this increased thrust capability is accompanied by reduced fan stall margin and can be realized during flight conditions where engine face distortion is low. The results of analyses and simulations also show that engine thrust response is improved and that fuel consumption can be reduced. Although the performance benefits that accrue because of airframe and engine control integration are being demonstrated on an F-15 aircraft, the principles are applicable to advanced aircraft such as the advanced tactical fighter and advanced tactical aircraft.

  7. International Interlaboratory Digital PCR Study Demonstrating High Reproducibility for the Measurement of a Rare Sequence Variant.

    PubMed

    Whale, Alexandra S; Devonshire, Alison S; Karlin-Neumann, George; Regan, Jack; Javier, Leanne; Cowen, Simon; Fernandez-Gonzalez, Ana; Jones, Gerwyn M; Redshaw, Nicholas; Beck, Julia; Berger, Andreas W; Combaret, Valérie; Dahl Kjersgaard, Nina; Davis, Lisa; Fina, Frederic; Forshew, Tim; Fredslund Andersen, Rikke; Galbiati, Silvia; González Hernández, Álvaro; Haynes, Charles A; Janku, Filip; Lacave, Roger; Lee, Justin; Mistry, Vilas; Pender, Alexandra; Pradines, Anne; Proudhon, Charlotte; Saal, Lao H; Stieglitz, Elliot; Ulrich, Bryan; Foy, Carole A; Parkes, Helen; Tzonev, Svilen; Huggett, Jim F

    2017-02-07

    This study tested the claim that digital PCR (dPCR) can offer highly reproducible quantitative measurements in disparate laboratories. Twenty-one laboratories measured four blinded samples containing different quantities of a KRAS fragment encoding G12D, an important genetic marker for guiding therapy of certain cancers. This marker is challenging to quantify reproducibly using quantitative PCR (qPCR) or next generation sequencing (NGS) due to the presence of competing wild type sequences and the need for calibration. Using dPCR, 18 laboratories were able to quantify the G12D marker within 12% of each other in all samples. Three laboratories appeared to measure consistently outlying results; however, proper application of a follow-up analysis recommendation rectified their data. Our findings show that dPCR has demonstrable reproducibility across a large number of laboratories without calibration. This could enable the reproducible application of molecular stratification to guide therapy and, potentially, for molecular diagnostics.

  8. Automatic three-dimensional tracking of particles with high-numerical-aperture digital lensless holographic microscopy.

    PubMed

    Restrepo, John F; Garcia-Sucerquia, Jorge

    2012-02-15

    We present an automatic procedure for 3D tracking of micrometer-sized particles with high-NA digital lensless holographic microscopy. The method uses a two-feature approach to search for the best focal planes and to distinguish particles from artifacts or other elements on the reconstructed stream of the holograms. A set of reconstructed images is axially projected onto a single image. From the projected image, the centers of mass of all the reconstructed elements are identified. Starting from the centers of mass, the morphology of the profile of the maximum intensity along the reconstruction direction allows for the distinguishing of particles from others elements. The method is tested with modeled holograms and applied to automatically track micrometer-sized bubbles in a sample of 4 mm3 of soda.

  9. High resolution digital holographic microscopy for the study of aggregated natural cellulose nanowhisker fibers

    NASA Astrophysics Data System (ADS)

    Wahba, H. H.; Sjödahl, M.; Gren, P.; Olsson, E.

    2015-10-01

    In this paper, digital holographic (DH) microscopy demonstrates its ability to perform a full characterization of nanofibers. The high resolution and magnification of the presented method to study the nanofibers are tested using standard MIL-STD-150A 1951 USAF resolution test target. In this investigation, aggregated natural cellulose nanowhisker fibers are positioned in the front of the microscopic objective using a 3D translation stage in the object arm of DH setup. The recorded off-axis holograms are refocused using the angular spectrum method. The reconstructed complex field is used to calculate optical phase and intensity distributions of the object at different reconstruction depths. A simple algorithm is used to define the focused image with suitable accuracy. The dimensions and orientation of the fibers can be evaluated from the optical field at different depths. Then, the shape and textures along the aggregated natural cellulose nanowhisker fiber can be presented in a 3D space.

  10. High-throughput phenotyping of plant populations using a personal digital assistant.

    PubMed

    Vankudavath, Raju Naik; Bodanapu, Reddaiah; Sreelakshmi, Yellamaraju; Sharma, Rameshwar

    2012-01-01

    During many biological experiments voluminous data is acquired, which can be best collected with -portable data acquisition devices and later analyzed with a personal computer (PC). Public domain software catering to data acquisition and analysis is currently limited. The necessity of phenotyping large plant populations led to the development of the application "PHENOME" to manage the data. PHENOME allows acquisition of phenotypic data using a personal digital assistant (PDA) with a built-in barcode scanner. The acquired data can be exported to a customized database on a PC for further analysis and cataloging. PHENOME can be used for a variety of applications, for example high-throughput phenotyping of a mutagenized or mapping population, or phenotyping of several individuals in one or more ecological niches.

  11. Design of a high-speed digital processing element for parallel simulation

    NASA Technical Reports Server (NTRS)

    Milner, E. J.; Cwynar, D. S.

    1983-01-01

    A prototype of a custom designed computer to be used as a processing element in a multiprocessor based jet engine simulator is described. The purpose of the custom design was to give the computer the speed and versatility required to simulate a jet engine in real time. Real time simulations are needed for closed loop testing of digital electronic engine controls. The prototype computer has a microcycle time of 133 nanoseconds. This speed was achieved by: prefetching the next instruction while the current one is executing, transporting data using high speed data busses, and using state of the art components such as a very large scale integration (VLSI) multiplier. Included are discussions of processing element requirements, design philosophy, the architecture of the custom designed processing element, the comprehensive instruction set, the diagnostic support software, and the development status of the custom design.

  12. Spatio-temporal experiments of volume elastic objects with high speed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Pérez López, C.; Hernández Montes, M. S.; Mendoza Santoyo, F.; Gutiérrez Hernandez, D. A.

    2011-08-01

    The optical non-destructive digital holographic interferometry (DHI) technique has proven to be a powerful tool in measuring vibration phenomena with a spatial resolution ranging from a few hundreds of nanometers to tens of micrometers. With the aid of high speed digital cameras it is possible to achieve simultaneously spatial and temporal resolution, and thus capable of measuring the entire object mechanical oscillation trajectory from one to several cycles. It is important to mention that due to faster computers with large data storage capacity there is an increasing interest in applying numerical simulation methods to mimic different real life objects for example, in the field of modern elastic materials and biological systems. The complex algorithms involved cannot render significant results mainly due to the rather large number of variables. In order to test these numerical simulations some experiments using optical techniques have been designed and reported. This is very important for example in measurements of the dynamic elastic properties of materials. In this work we present some preliminary results from experiments that use DHI to measure vibrations of an elastic spherical object subject to a mechanical excitation that induces resonant vibration modes in its volume. We report on the spatial and temporal effects that by their nature have a non-linear mechanical response. The use of a high speed CMOS camera in DHI assures the measurement of this nonlinear behavior as a sum of linear effects that happen during very short time lapses and with very small displacement amplitudes. We conclude by stating that complex numerical models may be compared to results using DHI, thus proposing an alternative method to prove and verify the mathematical models vs. real measurements on volumetric elastic objects.

  13. High-speed, digitally refocused retinal imaging with line-field parallel swept source OCT

    NASA Astrophysics Data System (ADS)

    Fechtig, Daniel J.; Kumar, Abhishek; Ginner, Laurin; Drexler, Wolfgang; Leitgeb, Rainer A.

    2015-03-01

    MHz OCT allows mitigating undesired influence of motion artifacts during retinal assessment, but comes in state-of-the-art point scanning OCT at the price of increased system complexity. By changing the paradigm from scanning to parallel OCT for in vivo retinal imaging the three-dimensional (3D) acquisition time is reduced without a trade-off between speed, sensitivity and technological requirements. Furthermore, the intrinsic phase stability allows for applying digital refocusing methods increasing the in-focus imaging depth range. Line field parallel interferometric imaging (LPSI) is utilizing a commercially available swept source, a single-axis galvo-scanner and a line scan camera for recording 3D data with up to 1MHz A-scan rate. Besides line-focus illumination and parallel detection, we mitigate the necessity for high-speed sensor and laser technology by holographic full-range imaging, which allows for increasing the imaging speed by low sampling of the optical spectrum. High B-scan rates up to 1kHz further allow for implementation of lable-free optical angiography in 3D by calculating the inter B-scan speckle variance. We achieve a detection sensitivity of 93.5 (96.5) dB at an equivalent A-scan rate of 1 (0.6) MHz and present 3D in vivo retinal structural and functional imaging utilizing digital refocusing. Our results demonstrate for the first time competitive imaging sensitivity, resolution and speed with a parallel OCT modality. LPSI is in fact currently the fastest OCT device applied to retinal imaging and operating at a central wavelength window around 800 nm with a detection sensitivity of higher than 93.5 dB.

  14. Transgenic rice seed synthesizing diverse flavonoids at high levels: a new platform for flavonoid production with associated health benefits.

    PubMed

    Ogo, Yuko; Ozawa, Kenjiro; Ishimaru, Tsutomu; Murayama, Tsugiya; Takaiwa, Fumio

    2013-08-01

    Flavonoids possess diverse health-promoting benefits but are nearly absent from rice, because most of the genes encoding enzymes for flavonoid biosynthesis are not expressed in rice seeds. In the present study, a transgenic rice plant producing several classes of flavonoids in seeds was developed by introducing multiple genes encoding enzymes involved in flavonoid synthesis, from phenylalanine to the target flavonoids, into rice. Rice accumulating naringenin was developed by introducing phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes. Rice producing other classes of flavonoids, kaempferol, genistein, and apigenin, was developed by introducing, together with PAL and CHS, genes encoding flavonol synthase/flavanone-3-hydroxylase, isoflavone synthase, and flavone synthases, respectively. The endosperm-specific GluB-1 promoter or embryo- and aleurone-specific 18-kDa oleosin promoters were used to express these biosynthetic genes in seed. The target flavonoids of naringenin, kaempferol, genistein, and apigenin were highly accumulated in each transgenic rice, respectively. Furthermore, tricin was accumulated by introducing hydroxylase and methyltransferase, demonstrating that modification to flavonoid backbones can be also well manipulated in rice seeds. The flavonoids accumulated as both aglycones and several types of glycosides, and flavonoids in the endosperm were deposited into PB-II-type protein bodies. Therefore, these rice seeds provide an ideal platform for the production of particular flavonoids due to efficient glycosylation, the presence of appropriate organelles for flavonoid accumulation, and the small effect of endogenous enzymes on the production of flavonoids by exogenous enzymes.

  15. Highly textured fresnoite thin films synthesized in situ by pulsed laser deposition with CO2 laser direct heating

    NASA Astrophysics Data System (ADS)

    Lorenz, Michael; de Pablos-Martin, Araceli; Patzig, Christian; Stölzel, Marko; Brachwitz, Kerstin; Hochmuth, Holger; Grundmann, Marius; Höche, Thomas

    2014-01-01

    Fresnoite Ba2TiSi2O8 (BTS) thin films were grown and crystallized in situ using pulsed laser deposition (PLD) with CO2 laser direct heating of the a-plane sapphire (1 1 0) substrates up to 1250 °C. Starting with 775 °C growth temperature, (0 0 1)- and (1 1 0)-textured BTS and BaTiO3 phases, respectively, could be assigned in the films, and the typical fern-like BTS crystallization patterns appear. For higher process temperatures of 1100 to 1250 °C, atomically smooth, terraced surface of the films was found, accompanied by crystalline high-temperature phases of Ba-Ti-Si oxides. HAADF micrographs taken in both scanning transmission electron microscopy and energy-dispersive x-ray spectrometry mode show details of morphology and elemental distribution inside the films and at the interface. To balance the inherent Si deficiency of the BTS films, growth from glassy BTS × 2 SiO2 and BTS × 2.5 SiO2 targets was considered as well. The latter targets are ideal for PLD since the employed glasses possess 100% of the theoretical density and are homogeneous at the atomic scale.

  16. Antioxidant properties of thio-caffeine derivatives: Identification of the newly synthesized 8-[(pyrrolidin-1-ylcarbonothioyl)sulfanyl]caffeine as antioxidant and highly potent cytoprotective agent.

    PubMed

    Jasiewicz, Beata; Sierakowska, Arleta; Wandyszewska, Natalia; Warżajtis, Beata; Rychlewska, Urszula; Wawrzyniak, Rafał; Mrówczyńska, Lucyna

    2016-08-15

    A series of nine thio-caffeine analogues were synthesized and characterised by NMR, FT-IR and MS spectroscopic methods. Molecular structures of four of them were determined using single crystal X-ray diffraction methods. The antioxidant properties of all compounds, at concentration ranges from 0.025 to 0.1mg/mL, were evaluated by various chemical- and cell-based antioxidant assays. Human erythrocytes were used to examine in vitro haemolytic activity of all compounds and their protective effect against oxidative haemolysis induced by AAPH, one of the commonly used free radical generator. All compounds studied showed no effect on the human erythrocytes membrane structure and permeability with the exception of 8-(phenylsulfanyl)caffeine. Among the nine caffeine thio-analogues tested, the newly synthesized 8-[(pyrrolidin-1-ylcarbonothioyl)sulfanyl]caffeine possessed exceptionally high antioxidant properties. Moreover, it protects human erythrocytes against AAPH-induced oxidative damage as efficiently as the standard antioxidant Trolox. Therefore, 8-[(pyrrolidin-1-ylcarbonothioyl)sulfanyl]caffeine may have a significant cytoprotective potential caused by its antioxidant activity.

  17. Direct atomic-level observation and chemical analysis of ZnSe synthesized by in situ high-throughput reactive fiber drawing.

    PubMed

    Hou, Chong; Jia, Xiaoting; Wei, Lei; Stolyarov, Alexander M; Shapira, Ofer; Joannopoulos, John D; Fink, Yoel

    2013-03-13

    We demonstrate a high-throughput method for synthesizing zinc selenide (ZnSe) in situ during fiber drawing. Central to this method is a thermally activated chemical reaction occurring across multiple interfaces between alternately layered elemental zinc- (Zn-) and selenium- (Se-) rich films embedded in a preform and drawn into meters of fiber at a temperature well below the melting temperature of either Zn or ZnSe. By depositing 50 nm thick layers of Zn interleaved between 1 μm thick Se layers, a controlled breakup of the Zn sheet is achieved, thereby enabling a complete and controlled chemical reaction. The thermodynamics and kinetics of this synthesis process are studied using thermogravimetric analysis and differential scanning calorimetry, and the in-fiber compound is analyzed by a multiplicity of materials characterization tools, including transmission electron microscopy, Raman microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, all resulting in unambiguous identification of ZnSe as the compound produced from the reactive fiber draw. Furthermore, we characterize the in-fiber ZnSe/Se97S3 heterojunction to demonstrate the prospect of ZnSe-based fiber optoelectronic devices. The ability to synthesize new compounds during fiber drawing at nanometer scale precision and to characterize them at the atomic-level extends the architecture and materials selection compatible with multimaterial fiber drawing, thus paving the way toward more complex and sophisticated functionality.

  18. High-value utilization of lignin to synthesize Ag nanoparticles with detection capacity for Hg²⁺.

    PubMed

    Shen, Zuguang; Luo, Yuqiong; Wang, Qun; Wang, Xiaoying; Sun, Runcang

    2014-09-24

    This study reports the rapid preparation of silver nanoparticles (AgNPs) from Tollens' reagent under microwave irradiation. In the synthesis, lignin with reducing groups and spatial three-dimensional structure was used as reducing and stabilizing agents without other chemical reagents, and the effects of the ratio of lignin to Ag(+), reaction temperature, and heating time on the synthesis of AgNPs were investigated. The obtained AgNPs were further characterized by UV-vis, Malvern particle size, TEM, XRD, and XPS analyses. The structural changes of lignin before and after reaction were also studied by FT-IR, (1)H NMR, (13)C NMR, and GC-MS. The results revealed that the obtained AgNPs were mostly spherical with diameters of around 24 nm. The optimum reaction conditions were a ratio 50 mg of lignin to 0.3 mM of Ag(+), a microwave irradiation temperature of 60 °C, and a heating time of 10 min. Moreover, AgNPs redispersed well in water and ethanol after centrifugation for the removal of lignin. During the formation of AgNPs, lignin was oxidized, and the side chains of lignin were partly disrupted into small molecules, such as hydrocarbon and alcohol. The resultant lignin-AgNPs showed highly selective sensing detection for Hg(2+), and the color of the lignin-AgNP solution containing Hg(2+) decreased gradually with increasing amounts of Hg(2+) within seconds, but the other 19 metal ions had little effect on the color and surface plasmon absorption band of the lignin-AgNPs. Also, there was a linear relationship between the absorbance and Hg(2+) concentration, with a limit of detection concentration of 23 nM. This study provides not only a new way to take advantage of agricultural and forestry residues, but also a green and rapid method for the synthesis of AgNPs to detect the toxic ion Hg(2+) selectively and sensitively.

  19. High-resolution structural and elemental analyses of calcium storage structures synthesized by the noble crayfish Astacus astacus.

    PubMed

    Luquet, Gilles; Salomé, Murielle; Ziegler, Andreas; Paris, Céline; Percot, Aline; Dauphin, Yannicke

    2016-11-01

    During premolt, crayfish develop deposits of calcium ions, called gastroliths, in their stomach wall. The stored calcium is used for the calcification of parts of the skeleton regularly renewed for allowing growth. Structural and molecular analyses of gastroliths have been primarily performed on three crayfish species, Orconectes virilis, Procambarus clarkii, and more recently, Cherax quadricarinatus. We have performed high-resolution analyses of gastroliths from the native noble crayfish, Astacus astacus, focusing on the microstructure, the mineralogical and elemental composition and distribution in a comparative perspective. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) observations showed a classical layered microstructure composed of 200-nm diameter granules aligned along fibers. These granules are themselves composed of agglomerated nanogranules of 50nm-mean diameters. Denser regions of bigger fused granules are also present. Micro-Raman spectroscopy show that if A. astacus gastroliths, similarly to the other analyzed gastroliths, are mainly composed of amorphous calcium carbonate (ACC), they are also rich in amorphous calcium phosphate (ACP). The presence of a carotenoid pigment is also observed in A. astacus gastrolith contrary to C. quadricarinatus. Energy-dispersive X-ray spectroscopy (EDX) analyses demonstrate the presence of minor elements such as Mg, Sr, Si and P. The distribution of this last element is particularly heterogeneous. X-ray absorption near edge structure spectroscopy (XANES) reveals an alternation of layers more or less rich in phosphorus evidenced in the mineral phase as well as in the organic matrix in different molecular forms. Putative functions of the different P-comprising molecules are discussed.

  20. High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data

    SciTech Connect

    Fan, X.; Strauss, M.A.; Schneider, D.P.; Gunn, J.E.; Lupton, R.H.; Yanny, B.; Anderson, S.F.; Anderson, J.E. Jr.; Annis, J.; Bahcall, N.A.; Bakken, J.A.; Bastian, S.; Berman, E.; Boroski, W.N.; Briegel, C.; Briggs, J.W.; Brinkmann, J.; Carr, M.A.; Colestock, P.L.; Connolly, A.J.; Crocker, J.H.; Csabai, I. |; Davis, J.E.; and others

    1999-07-01

    We present photometric and spectroscopic observations of 15 high-redshift quasars (z{gt}3.6) discovered from {approximately}140 deg{sup 2} of five-color ({ital u}{prime}, {ital g}{prime}, {ital r}{prime}, {ital i}{prime}, and {ital z}{prime}) imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The quasars are selected by their distinctive colors in SDSS multicolor space. Four of the quasars have redshifts higher than 4.6 (z=4.63, 4.75, 4.90, and 5.00, the latter being the highest redshift quasar yet known). In addition, two previously known z{gt}4 objects were recovered from the data. The quasars all have i{sup *} {lt}20 and have luminosities comparable to that of 3C 273. The spectra of the quasars have similar features (strong, broad emission lines and substantial absorption blueward of the Ly{alpha} emission line) seen in previously known high-redshift quasars. Although the photometric accuracy and image quality fail to meet the final survey requirements, our success rate for identifying high-redshift quasars (17 quasars from 27 candidates) is much higher than that of previous multicolor surveys. However, the numbers of high-redshift quasars found is in close accord with the number density inferred from previous surveys. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}

  1. A high-accuracy digital star tracker for advanced planetary missions

    NASA Technical Reports Server (NTRS)

    Salomon, P. M.; Crawford, W. E.

    1973-01-01

    The digital star tracker represents a novel departure from previous analog designs in terms of circuit implementation and operational capabilities. As an element of an all-digital spacecraft control system, it combines proven low-level analog signal processing with digital error control and command functions. Additional capabilities that are obtainable with the digital circuitry include programmable intensity threshold gates, commanded electronic pointing control, and an acquisition/control algorithm which minimizes the effects of straylight disturbances. The capabilities inherent in the implementation have been successfully demonstrated in a laboratory model of the instrument.

  2. A high-accuracy digital star tracker for advanced planetary missions.

    NASA Technical Reports Server (NTRS)

    Salomon, P. M.; Crawford, W. E.

    1972-01-01

    The digital star tracker represents a novel departure from previous analog designs in terms of circuit implementation and operational capabilities. As an element of an all-digital spacecraft control system, it combines proven low-level analog signal processing with digital error control and command functions. Additional capabilities that are obtainable with the digital circuitry include programmable intensity threshold gates, commanded electronic pointing control, and an acquisition/control algorithm which minimizes the effects of straylight disturbances. The capabilities inherent in the implementation have been successfully demonstrated in a laboratory model of the instrument.

  3. In situ synthesized 3D heterometallic metal-organic framework (MOF) as a high-energy-density material shows high heat of detonation, good thermostability and insensitivity.

    PubMed

    Feng, Yaya; Liu, Xiangyu; Duan, Linqiang; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Yang, Xuwu; Gao, Shengli

    2015-02-07

    A reticular 3D heterometallic metal-organic framework (MOF), [Cu4Na(Mtta)5(CH3CN)]n () (N% = 40.08%), has been synthesized, using a 5-methyl tetrazole (Mtta) ligand formed from acetonitrile and azide, through in situ synthesis and structurally characterized by X-ray single crystal diffraction. The fluorescence spectra demonstrate that undergoes an interesting structural transformation in aqueous solution, yielding the compound [Cu4Na(Mtta)5H2O]n () as confirmed by (1)H NMR, IR and PXRD. Thermoanalysis showed that possesses excellent thermostability up to 335 °C. The calculated detonation properties and the sensitivity test illustrate that compound could be used as a potential explosive. In addition, the non-isothermal kinetics for were studied using the Kissinger and Ozawa-Doyle methods. The enthalpy of formation was obtained from the determination of the constant-volume combustion energy.

  4. From high dilutions to digital biology: the physical nature of the biological signal.

    PubMed

    Thomas, Yolène

    2015-10-01

    The memory of water was a radical idea that arose in the laboratory of Jacques Benveniste in the late 1980s. Twenty-five years have passed and yet the often angry debate on its merits continues despite the increasing number of scientists who have reported confirmation of the basic results. One working hypothesis was that molecules can communicate with each other, exchanging information without being in physical contact and that at least some biological functions can be mimicked by certain energetic modes characteristics of a given molecule. These considerations informed exploratory research which led to the speculation that biological signaling might be transmissible by electromagnetic means. Around 1991, the transfer of specific molecular signals to sensitive biological systems was achieved using an amplifier and electromagnetic coils. In 1995, a more sophisticated procedure was established to record, digitize and replay these signals using a multimedia computer. From a physical and chemical perspective, these experiments pose a riddle, since it is not clear what mechanism can sustain such 'water memory' of the exposure to molecular signals. From a biological perspective, the puzzle is what nature of imprinted effect (water structure) can impact biological function. A parallel can be drawn between this debate on the memory of water, which presumes that the action of molecules is mediated by an electromagnetic phenomenon, and the often acrimonious debate on the transmission of nerve influxes via synaptic transfer of specific molecules, neurotransmitters. The latter debate began in 1921 with the first experiments by Loewi and was still active in 1949, 28 years later. A strong reluctance to accept research that questions basic aspects of long-accepted biochemical paradigms is to be expected. In this paper we will provide a brief summary of experiments relating to the memory of water: the earlier work on high dilutions (HD) and then the experiments, which followed and

  5. Structure-Property Correlation in Fe-Al2O3 In Situ Nanocomposite Synthesized by High-Energy Ball Milling and Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Udhayabanu, V.; Ravi, K. R.; Murty, B. S.

    2016-10-01

    In the present study, Fe-10 vol pct Al2O3 in situ nanocomposite has been derived by high-energy ball milling of Fe2O3-Fe-Al powder mixture followed by the consolidation using spark plasma sintering (SPS). The consolidated nanocomposite has bimodal-grained structure consisting of nanometer- and submicron-sized Fe grains along with nanometer-sized Al2O3, and Fe3O4 particles. The mechanical property analysis reveals that compressive yield strength of Fe-10 vol pct Al2O3 nanocomposite is 2100 MPa which is nearly two times higher than that of monolithic Fe processed by Mechanical Milling and SPS. The strengthening contributions obtained from matrix, grain size, and particles in the synthesized nanocomposite have been calculated theoretically, and are found to be matching well with the experimental strength levels.

  6. Exploring the potential of high resolution mass spectrometry for the investigation of lignin-derived phenol substitutes in phenolic resin syntheses.

    PubMed

    Dier, Tobias K F; Fleckenstein, Marco; Militz, Holger; Volmer, Dietrich A

    2017-03-23

    Chemical degradation is an efficient method to obtain bio-oils and other compounds from lignin. Lignin bio-oils are potential substitutes for the phenol component of phenol formaldehyde (PF) resins. Here, we developed an analytical method based on high resolution mass spectrometry that provided structural information for the synthesized lignin-derived resins and supported the prediction of their properties. Different model resins based on typical lignin degradation products were analyzed by electrospray ionization in negative ionization mode. Utilizing enhanced mass defect filter techniques provided detailed structural information of the lignin-based model resins and readily complemented the analytical data from differential scanning calorimetry and thermogravimetric analysis. Relative reactivity and chemical diversity of the phenol substitutes were significant determinants of the outcome of the PF resin synthesis and thus controlled the areas of application of the resulting polymers. Graphical abstract ᅟ.

  7. Transfer of herpes simplex virus thymidine kinase synthesized in bacteria by a high-expression plasmid to tissue culture cells by protoplast fusion

    SciTech Connect

    Waldman, A.S.; Milman, G.

    1984-08-01

    The introduction of a protein into living tissue culture cells may permit the in vivo study of functions of the protein. The authors have previously described a high-efficiency-expression plasmid, pHETK2, containing the herpes simplex virus type 1 thymidine kinase (TK) gene which, upon temperature induction, causes TK to be synthesized as greater than 4% of the bacterial protein. In this report it is shown that enzymatically active TK was transferred to mouse Ltk- cells by polyethylene glycol-mediated fusion with protoplasts prepared from bacteria containing induced levels of TK. The presence of TK in the Ltk- cells was detected by the incorporation of (/sup 3/H)thymidine into cell nuclei as measured by autoradiography.

  8. High-resolution focal plane array IR detection modules and digital signal processing technologies at AIM

    NASA Astrophysics Data System (ADS)

    Cabanski, Wolfgang A.; Breiter, Rainer; Koch, R.; Mauk, Karl-Heinz; Rode, Werner; Ziegler, Johann; Eberhardt, Kurt; Oelmaier, Reinhard; Schneider, Harald; Walther, Martin

    2000-07-01

    Full video format focal plane array (FPA) modules with up to 640 X 512 pixels have been developed for high resolution imaging applications in either mercury cadmium telluride (MCT) mid wave (MWIR) infrared (IR) or platinum silicide (PtSi) and quantum well infrared photodetector (QWIP) technology as low cost alternatives to MCT for high performance IR imaging in the MWIR or long wave spectral band (LWIR). For the QWIP's, a new photovoltaic technology was introduced for improved NETD performance and higher dynamic range. MCT units provide fast frame rates > 100 Hz together with state of the art thermal resolution NETD < 20 mK for short snapshot integration times of typically 2 ms. PtSi and QWIP modules are usually operated in a rolling frame integration mode with frame rates of 30 - 60 Hz and provide thermal resolutions of NETD < 80 mK for PtSi and NETD < 20 mK for QWIP, respectively. Due to the lower quantum efficiency compared to MCT, however, the integration time is typically chosen to be as long 10 - 20 ms. The heat load of the integrated detector cooler assemblies (IDCAs) could be reduced to an amount as low, that a 1 W split liner cooler provides sufficient cooling power to operate the modules -- including the QWIP with 60 K operation temperature -- at ambient temperatures up to 65 degrees Celsius. Miniaturized command/control electronics (CCE) available for all modules provide a standardized digital interface, with 14 bit analogue to digital conversion for state to the art correctability, access to highly dynamic scenes without any loss of information and simplified exchangeability of the units. New modular image processing hardware platforms and software for image visualization and nonuniformity correction including scene based self learning algorithms had to be developed to accomplish for the high data rates of up to 18 M pixels/s with 14-bit deep data, allowing to take into account nonlinear effects to access the full NETD by accurate reduction of residual

  9. On the Performance of the Martin Digital Filter for High- and Low-pass Applications

    NASA Technical Reports Server (NTRS)

    Mcclain, C. R.

    1979-01-01

    A nonrecursive numerical filter is described in which the weighting sequence is optimized by minimizing the excursion from the ideal rectangular filter in a least squares sense over the entire domain of normalized frequency. Additional corrections to the weights in order to reduce overshoot oscillations (Gibbs phenomenon) and to insure unity gain at zero frequency for the low pass filter are incorporated. The filter is characterized by a zero phase shift for all frequencies (due to a symmetric weighting sequence), a finite memory and stability, and it may readily be transformed to a high pass filter. Equations for the filter weights and the frequency response function are presented, and applications to high and low pass filtering are examined. A discussion of optimization of high pass filter parameters for a rather stringent response requirement is given in an application to the removal of aircraft low frequency oscillations superimposed on remotely sensed ocean surface profiles. Several frequency response functions are displayed, both in normalized frequency space and in period space. A comparison of the performance of the Martin filter with some other commonly used low pass digital filters is provided in an application to oceanographic data.

  10. Highly sensitive and quantitative evaluation of the EGFR T790M mutation by nanofluidic digital PCR.

    PubMed

    Iwama, Eiji; Takayama, Koichi; Harada, Taishi; Okamoto, Isamu; Ookubo, Fumihiko; Kishimoto, Junji; Baba, Eishi; Oda, Yoshinao; Nakanishi, Yoichi

    2015-08-21

    The mutation of T790M in EGFR is a major mechanism of resistance to treatment with EGFR-TKIs. Only qualitative detection (presence or absence) of T790M has been described to date, however. Digital PCR (dPCR) analysis has recently been applied to the quantitative detection of target molecules in cancer with high sensitivity. In the present study, 25 tumor samples (13 obtained before and 12 after EGFR-TKI treatment) from 18 NSCLC patients with activating EGFR mutations were evaluated for T790M with dPCR. The ratio of the number of T790M alleles to that of activating mutation alleles (T/A) was determined. dPCR detected T790M in all 25 samples. Although T790M was present in all pre-TKI samples from 13 patients, 10 of these patients had a low T/A ratio and manifested substantial tumor shrinkage during treatment with EGFR-TKIs. In six of seven patients for whom both pre- and post-TKI samples were available, the T/A ratio increased markedly during EGFR-TKI treatment. Highly sensitive dPCR thus detected T790M in all NSCLC patients harboring activating EGFR mutations whether or not they had received EGFR-TKI treatment. Not only highly sensitive but also quantitative detection of T790M is important for evaluation of the contribution of T790M to EGFR-TKI resistance.

  11. High-throughput screening of high Monascus pigment-producing strain based on digital image processing.

    PubMed

    Xia, Meng-lei; Wang, Lan; Yang, Zhi-xia; Chen, Hong-zhang

    2016-04-01

    This work proposed a new method which applied image processing and support vector machine (SVM) for screening of mold strains. Taking Monascus as example, morphological characteristics of Monascus colony were quantified by image processing. And the association between the characteristics and pigment production capability was determined by SVM. On this basis, a highly automated screening strategy was achieved. The accuracy of the proposed strategy is 80.6 %, which is compatible with the existing methods (81.1 % for microplate and 85.4 % for flask). Meanwhile, the screening of 500 colonies only takes 20-30 min, which is the highest rate among all published results. By applying this automated method, 13 strains with high-predicted production were obtained and the best one produced as 2.8-fold (226 U/mL) of pigment and 1.9-fold (51 mg/L) of lovastatin compared with the parent strain. The current study provides us with an effective and promising method for strain improvement.

  12. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Abdel Hafiz, M.; Micalizio, S.; Boudot, R.

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad2/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad2/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10-14 for the Cs cell clock and 2 × 10-14 for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10-15 level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  13. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    SciTech Connect

    François, B.; Calosso, C. E.; Micalizio, S.; Abdel Hafiz, M.; Boudot, R.

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  14. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks.

    PubMed

    François, B; Calosso, C E; Abdel Hafiz, M; Micalizio, S; Boudot, R

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad(2)/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad(2)/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10(-14) for the Cs cell clock and 2 × 10(-14) for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10(-15) level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  15. A New Statistics-Based Online Baseline Restorer for a High Count-Rate Fully Digital System.

    PubMed

    Li, Hongdi; Wang, Chao; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio; Liu, Shitao; An, Shaohui; Wong, Wai-Hoi

    2010-04-01

    The goal of this work is to develop a novel, accurate, real-time digital baseline restorer using online statistical processing for a high count-rate digital system such as positron emission tomography (PET). In high count-rate nuclear instrumentation applications, analog signals are DC-coupled for better performance. However, the detectors, pre-amplifiers and other front-end electronics would cause a signal baseline drift in a DC-coupling system, which will degrade the performance of energy resolution and positioning accuracy. Event pileups normally exist in a high-count rate system and the baseline drift will create errors in the event pileup-correction. Hence, a baseline restorer (BLR) is required in a high count-rate system to remove the DC drift ahead of the pileup correction. Many methods have been reported for BLR from classic analog methods to digital filter solutions. However a single channel BLR with analog method can only work under 500 kcps count-rate, and normally an analog front-end application-specific integrated circuits (ASIC) is required for the application involved hundreds BLR such as a PET camera. We have developed a simple statistics-based online baseline restorer (SOBLR) for a high count-rate fully digital system. In this method, we acquire additional samples, excluding the real gamma pulses, from the existing free-running ADC in the digital system, and perform online statistical processing to generate a baseline value. This baseline value will be subtracted from the digitized waveform to retrieve its original pulse with zero-baseline drift. This method can self-track the baseline without a micro-controller involved. The circuit consists of two digital counter/timers, one comparator, one register and one subtraction unit. Simulation shows a single channel works at 30 Mcps count-rate with pileup condition. 336 baseline restorer circuits have been implemented into 12 field-programmable-gate-arrays (FPGA) for our new fully digital PET system.

  16. Accuracy assessment of airborne photogrammetrically derived high-resolution digital elevation models in a high mountain environment

    NASA Astrophysics Data System (ADS)

    Müller, Johann; Gärtner-Roer, Isabelle; Thee, Patrick; Ginzler, Christian

    2014-12-01

    High-resolution digital elevation models (DEMs) generated by airborne remote sensing are frequently used to analyze landform structures (monotemporal) and geomorphological processes (multitemporal) in remote areas or areas of extreme terrain. In order to assess and quantify such structures and processes it is necessary to know the absolute accuracy of the available DEMs. This study assesses the absolute vertical accuracy of DEMs generated by the High Resolution Stereo Camera-Airborne (HRSC-A), the Leica Airborne Digital Sensors 40/80 (ADS40 and ADS80) and the analogue camera system RC30. The study area is located in the Turtmann valley, Valais, Switzerland, a glacially and periglacially formed hanging valley stretching from 2400 m to 3300 m a.s.l. The photogrammetrically derived DEMs are evaluated against geodetic field measurements and an airborne laser scan (ALS). Traditional and robust global and local accuracy measurements are used to describe the vertical quality of the DEMs, which show a non Gaussian distribution of errors. The results show that all four sensor systems produce DEMs with similar accuracy despite their different setups and generations. The ADS40 and ADS80 (both with a ground sampling distance of 0.50 m) generate the most accurate DEMs in complex high mountain areas with a RMSE of 0.8 m and NMAD of 0.6 m They also show the highest accuracy relating to flying height (0.14‰). The pushbroom scanning system HRSC-A produces a RMSE of 1.03 m and a NMAD of 0.83 m (0.21‰ accuracy of the flying height and 10 times the ground sampling distance). The analogue camera system RC30 produces DEMs with a vertical accuracy of 1.30 m RMSE and 0.83 m NMAD (0.17‰ accuracy of the flying height and two times the ground sampling distance). It is also shown that the performance of the DEMs strongly depends on the inclination of the terrain. The RMSE of areas up to an inclination <40° is better than 1 m. In more inclined areas the error and outlier occurrence

  17. Improvements in High Speed, High Resolution Dynamic Digital Image Correlation for Experimental Evaluation of Composite Drive System Components

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.; Ruggeri, Charles R.; Roberts, Gary D.; Handschuh, Robert Frederick

    2013-01-01

    Composite materials have the potential to reduce the weight of rotating drive system components. However, these components are more complex to design and evaluate than static structural components in part because of limited ability to acquire deformation and failure initiation data during dynamic tests. Digital image correlation (DIC) methods have been developed to provide precise measurements of deformation and failure initiation for material test coupons and for structures under quasi-static loading. Attempts to use the same methods for rotating components (presented at the AHS International 68th Annual Forum in 2012) are limited by high speed camera resolution, image blur, and heating of the structure by high intensity lighting. Several improvements have been made to the system resulting in higher spatial resolution, decreased image noise, and elimination of heating effects. These improvements include the use of a high intensity synchronous microsecond pulsed LED lighting system, different lenses, and changes in camera configuration. With these improvements, deformation measurements can be made during rotating component tests with resolution comparable to that which can be achieved in static tests

  18. Improvements in High Speed, High Resolution Dynamic Digital Image Correlation for Experimental Evaluation of Composite Drive System Components

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee; Ruggeri, Charles; Roberts, Gary; Handshuh, Robert

    2013-01-01

    Composite materials have the potential to reduce the weight of rotating drive system components. However, these components are more complex to design and evaluate than static structural components in part because of limited ability to acquire deformation and failure initiation data during dynamic tests. Digital image correlation (DIC) methods have been developed to provide precise measurements of deformation and failure initiation for material test coupons and for structures under quasi-static loading. Attempts to use the same methods for rotating components (presented at the AHS International 68th Annual Forum in 2012) are limited by high speed camera resolution, image blur, and heating of the structure by high intensity lighting. Several improvements have been made to the system resulting in higher spatial resolution, decreased image noise, and elimination of heating effects. These improvements include the use of a high intensity synchronous microsecond pulsed LED lighting system, different lenses, and changes in camera configuration. With these improvements, deformation measurements can be made during rotating component tests with resolution comparable to that which can be achieved in static tests.

  19. Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera.

    PubMed

    Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

    2016-03-04

    High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera.

  20. A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

    NASA Astrophysics Data System (ADS)

    Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Sertac Artan, N.; Froemke, Robert C.; Viventi, Jonathan

    2017-04-01

    Objective. High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach. We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results. The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance. We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but

  1. Parallel phase-shifting digital holography and its application to high-speed 3D imaging of dynamic object

    NASA Astrophysics Data System (ADS)

    Awatsuji, Yasuhiro; Xia, Peng; Wang, Yexin; Matoba, Osamu

    2016-03-01

    Digital holography is a technique of 3D measurement of object. The technique uses an image sensor to record the interference fringe image containing the complex amplitude of object, and numerically reconstructs the complex amplitude by computer. Parallel phase-shifting digital holography is capable of accurate 3D measurement of dynamic object. This is because this technique can reconstruct the complex amplitude of object, on which the undesired images are not superimposed, form a single hologram. The undesired images are the non-diffraction wave and the conjugate image which are associated with holography. In parallel phase-shifting digital holography, a hologram, whose phase of the reference wave is spatially and periodically shifted every other pixel, is recorded to obtain complex amplitude of object by single-shot exposure. The recorded hologram is decomposed into multiple holograms required for phase-shifting digital holography. The complex amplitude of the object is free from the undesired images is reconstructed from the multiple holograms. To validate parallel phase-shifting digital holography, a high-speed parallel phase-shifting digital holography system was constructed. The system consists of a Mach-Zehnder interferometer, a continuous-wave laser, and a high-speed polarization imaging camera. Phase motion picture of dynamic air flow sprayed from a nozzle was recorded at 180,000 frames per second (FPS) have been recorded by the system. Also phase motion picture of dynamic air induced by discharge between two electrodes has been recorded at 1,000,000 FPS, when high voltage was applied between the electrodes.

  2. Design and implementation of interface units for high speed fiber optics local area networks and broadband integrated services digital networks

    NASA Technical Reports Server (NTRS)

    Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph

    1990-01-01

    The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.

  3. Digital radiology using active matrix readout of amorphous selenium: detectors with high voltage protection.

    PubMed

    Zhao, W; Law, J; Waechter, D; Huang, Z; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector is being investigated for digital radiography and fluoroscopy. The detector uses a layer of amorphous selenium (a-Se) to convert x rays to a charge image, which is then electronically read out with a two-dimensional array of thin film transistors (TFTs). In order to sensitize the a-Se layer to x rays, a high voltage (of the order of several thousand volts) is applied to its top surface. The TFTs, which are at the bottom surface of the a-Se layer, are not subjected to any high voltage under normal radiological operational conditions since the pixel potential is < 10 V. However under a fault condition where these two events occur simultaneously: (1) suspended detector scan; and (2) an x-ray exposure more than ten times higher than normal, the voltage on the TFTs could rise to a damaging value. This paper describes a method for protecting the TFTs from high voltage damage under this fault condition. It employs a dual-gate TFT structure, one gate is for scanning control and the other is connected to the pixel electrode for high voltage protection. Before the pixel potential reaches a damaging value, the protection gate turns on the TFT automatically and drains excess charge away from the pixel thus providing a safe pixel saturation potential. In this paper, the characteristic curves of dual-gate TFTs are studied both theoretically and experimentally. The pixel x-ray response for imaging detectors with high voltage protection are predicted, and it is shown that with practical TFT designs the detector can provide a safe pixel saturation potential as well as satisfy the dynamic range required for diagnostic x-ray imaging applications.

  4. Automatic Generation of Building Mapping Using Digital, Vertical and Aerial High Resolution Photographs and LIDAR Point Clouds

    NASA Astrophysics Data System (ADS)

    Barragán, W.; Campos, A.; Sanchez, G.

    2016-06-01

    The objective of this research is automatic generation of buildings in the interest areas. This research was developed by using high resolution vertical aerial photographs and the LIDAR point cloud through radiometric and geometric digital processes. The research methodology usesknown building heights and various segmentation algorithms and spectral band combination. The overall effectiveness of the algorithm is 97.2% with the test data.

  5. A Connected Generation? Digital Inequalities in Elementary and High School Students According to Age and Socioeconomic Level

    ERIC Educational Resources Information Center

    Collin, Simon; Karsenti, Thierry; Ndimubandi, Alexis; Saffari, Hamid

    2016-01-01

    The objective of this article was to better understand the relationship between students' age and socioeconomic level, and its influence on students' digital uses. We conducted a quantitative study of 401 elementary and high school students in Quebec. Four independent variables were initially selected: two related to age (actual age and education…

  6. Hierarchical object-based classification of ultra-high-resolution digital mapping camera (DMC) imagery for rangeland mapping and assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultra high resolution digital aerial photography has great potential to complement or replace ground measurements of vegetation cover for rangeland monitoring and assessment. We investigated object-based image analysis (OBIA) techniques for classifying vegetation in southwestern U.S. arid rangelands...

  7. Synthetic streak images (x-t diagrams) from high-speed digital video records

    NASA Astrophysics Data System (ADS)

    Settles, Gary

    2013-11-01

    Modern digital video cameras have entirely replaced the older photographic drum and rotating-mirror cameras for recording high-speed physics phenomena. They are superior in almost every regard except, at speeds approaching one million frames/s, sensor segmentation results in severely reduced frame size, especially height. However, if the principal direction of subject motion is arranged to be along the frame length, a simple Matlab code can extract a row of pixels from each frame and stack them to produce a pseudo-streak image or x-t diagram. Such a 2-D image can convey the essence of the large volume of information contained in a high-speed video sequence, and can be the basis for the extraction of quantitative velocity data. Examples include streak shadowgrams of explosions and gunshots, streak schlieren images of supersonic cavity-flow oscillations, and direct streak images of shock-wave motion in polyurea samples struck by gas-gun projectiles, from which the shock Hugoniot curve of the polymer is measured. This approach is especially useful, since commercial streak cameras remain very expensive and rooted in 20th-century technology.

  8. a Detailed Study about Digital Surface Model Generation Using High Resolution Satellite Stereo Imagery

    NASA Astrophysics Data System (ADS)

    Gong, K.; Fritsch, D.

    2016-06-01

    Photogrammetry is currently in a process of renaissance, caused by the development of dense stereo matching algorithms to provide very dense Digital Surface Models (DSMs). Moreover, satellite sensors have improved to provide sub-meter or even better Ground Sampling Distances (GSD) in recent years. Therefore, the generation of DSM from spaceborne stereo imagery becomes a vivid research area. This paper presents a comprehensive study about the DSM generation of high resolution satellite data and proposes several methods to implement the approach. The bias-compensated Rational Polynomial Coefficients (RPCs) Bundle Block Adjustment is applied to image orientation and the rectification of stereo scenes is realized based on the Project-Trajectory-Based Epipolarity (PTE) Model. Very dense DSMs are generated from WorldView-2 satellite stereo imagery using the dense image matching module of the C/C++ library LibTsgm. We carry out various tests to evaluate the quality of generated DSMs regarding robustness and precision. The results have verified that the presented pipeline of DSM generation from high resolution satellite imagery is applicable, reliable and very promising.

  9. Direct To Digital Holography For High Aspect Ratio Inspection of Semiconductor Wafers

    NASA Astrophysics Data System (ADS)

    Thomas, C. E. (Tommy); Hunt, Martin A.; Bahm, Tracy M.; Baylor, Larry R.; Bingham, Philip R.; Chidley, Matthew D.; Dai, Xiaolong; Delahanty, Robert J.; El-Khashab, Ayman; Gilbert, Judd M.; Goddard, James S.; Hanson, Gregory R.; Hickson, Joel D.; Hylton, Kathy W.; John, George C.; Jones, Michael L.; Mayo, Michael W.; Marek, Christopher; Price, John H.; Rasmussen, David A.; Schaefer, Louis J.; Schulze, Mark A.; Shen, Bichuan; Smith, Randall G.; Su, Allen N.; Tobin, Kenneth W.; Usry, William R.; Voelkl, Edgar; Weber, Karsten S.; Owen, Robert W.

    2003-09-01

    Direct to Digital Holography (DDH) has been developed as a semiconductor wafer inspection tool and in particular as a tool for seeing defects in high aspect ratio (HAR) structures on semiconductor wafers and also for seeing partial-height defects. While the tool works very well for general wafer inspection, it has unusual capabilities for high aspect ratio inspection (HARI) and for detecting thin residual film defects (partial height defects). Inspection of HAR structures is rated as one of the highest unmet priorities of the member companies of International SEMATECH, and finding residual thin film defects (in some cases called "stringers") is also a very difficult challenge. The capabilities that make DDH unusually sensitive include: 1) the capture of the whole wave—both the classical amplitude captured by traditional optical systems, and the phase of the wave, with phase potentially measured to ˜1/1000'th of a wavelength or ˜2 to 3 Angstroms for a deep ultra-violet (DUV) laser; 2) heterodyne detection—this allows it to capture very low signal levels; and 3) a head-on geometry using a collimated laser beam that allows best penetration of HAR structures. The basic features and methods of this patented technology are presented, along with simple calculations of signal strength and expected noise levels for various circumstances. Full-wave numerical calculations of electromagnetic field penetration into HAR contacts and experimental results from various wafer types and structures are also presented.

  10. High-Speed Microscale Optical Tracking Using Digital Frequency-Domain Multiplexing

    PubMed Central

    MacLachlan, Robert A.; Riviere, Cameron N.

    2010-01-01

    Position-sensitive detectors (PSDs), or lateral-effect photodiodes, are commonly used for high-speed, high-resolution optical position measurement. This paper describes the instrument design for multidimensional position and orientation measurement based on the simultaneous position measurement of multiple modulated sources using frequency-domain-multiplexed (FDM) PSDs. The important advantages of this optical configuration in comparison with laser/mirror combinations are that it has a large angular measurement range and allows the use of a probe that is small in comparison with the measurement volume. We review PSD characteristics and quantitative resolution limits, consider the lock-in amplifier measurement system as a communication link, discuss the application of FDM to PSDs, and make comparisons with time-domain techniques. We consider the phase-sensitive detector as a multirate DSP problem, explore parallels with Fourier spectral estimation and filter banks, discuss how to choose the modulation frequencies and sample rates that maximize channel isolation under design constraints, and describe efficient digital implementation. We also discuss hardware design considerations, sensor calibration, probe construction and calibration, and 3-D measurement by triangulation using two sensors. As an example, we characterize the resolution, speed, and accuracy of an instrument that measures the position and orientation of a 10 mm × 5 mm probe in 5 degrees of freedom (DOF) over a 30-mm cube with 4-μm peak-to-peak resolution at 1-kHz sampling. PMID:20428484

  11. High-Speed Microscale Optical Tracking Using Digital Frequency-Domain Multiplexing.

    PubMed

    Maclachlan, Robert A; Riviere, Cameron N

    2009-06-01

    Position-sensitive detectors (PSDs), or lateral-effect photodiodes, are commonly used for high-speed, high-resolution optical position measurement. This paper describes the instrument design for multidimensional position and orientation measurement based on the simultaneous position measurement of multiple modulated sources using frequency-domain-multiplexed (FDM) PSDs. The important advantages of this optical configuration in comparison with laser/mirror combinations are that it has a large angular measurement range and allows the use of a probe that is small in comparison with the measurement volume. We review PSD characteristics and quantitative resolution limits, consider the lock-in amplifier measurement system as a communication link, discuss the application of FDM to PSDs, and make comparisons with time-domain techniques. We consider the phase-sensitive detector as a multirate DSP problem, explore parallels with Fourier spectral estimation and filter banks, discuss how to choose the modulation frequencies and sample rates that maximize channel isolation under design constraints, and describe efficient digital implementation. We also discuss hardware design considerations, sensor calibration, probe construction and calibration, and 3-D measurement by triangulation using two sensors. As an example, we characterize the resolution, speed, and accuracy of an instrument that measures the position and orientation of a 10 mm × 5 mm probe in 5 degrees of freedom (DOF) over a 30-mm cube with 4-μm peak-to-peak resolution at 1-kHz sampling.

  12. Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey

    SciTech Connect

    Inada, Naohisa; Oguri, Masamune; Shin, Min-Su; Kayo, Issha; Strauss, Michael A.; Morokuma, Tomoki; Schneider, Donald P.; Becker, Robert H.; Bahcall, Neta A.; York, Donald G.

    2008-09-08

    We report the discovery of five gravitationally lensed quasars from the Sloan Digital Sky Survey (SDSS). All five systems are selected as two-image lensed quasar candidates from a sample of high-redshift (z > 2.2) SDSS quasars. We confirmed their lensing nature with additional imaging and spectroscopic observations. The new systems are SDSS J0819+5356 (source redshift z{sub s} = 2.237, lens redshift z{sub l} = 0.294, and image separation {theta} = 4.04 inch), SDSS J1254+2235 (z{sub s} = 3.626, {theta} = 1.56 inch), SDSS J1258+1657 (z{sub s} = 2.702, {theta} = 1.28 inch), SDSS J1339+1310 (z{sub s} = 2.243, {theta} = 1.69 cin), and SDSS J1400+3134 (z{sub s} = 3.317, {theta} = 1.74 inch). We estimate the lens redshifts of the latter four systems to be z{sub l} = 0.4-0.6 from the colors and magnitudes of the lensing galaxies. We find that the image configurations of all systems are well reproduced by standard mass models. Although these lenses will not be included in our statistical sample of z{sub s} < 2.2 lenses, they expand the number of lensed quasars which can be used for high-redshift galaxy and quasar studies.

  13. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2002-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  14. Characterizing vibratory kinematics in children and adults with high-speed digital imaging.

    PubMed

    Patel, Rita; Dubrovskiy, Denis; Döllinger, Michael

    2014-04-01

    PURPOSE The aim of this study is to quantify and identify characteristic vibratory motion in typically developing prepubertal children and young adults using high-speed digital imaging. METHOD The vibrations of the vocal folds were recorded from 27 children (ages 5-9 years) and 35 adults (ages 21-45 years), with high speed at 4,000 frames per second for sustained phonation. Kinematic features of amplitude periodicity, time periodicity, phase asymmetry, spatial symmetry, and glottal gap index were analyzed from the glottal area waveform across mean and standard deviation (i.e., intercycle variability) for each measure. RESULTS Children exhibited lower mean amplitude periodicity compared to men and women and lower time periodicity compared to men. Children and women exhibited greater variability in amplitude periodicity, time periodicity, phase asymmetry, and glottal gap index compared to men. Women had lower mean values of amplitude periodicity and time periodicity compared to men. CONCLUSION Children differed both spatially but more temporally in vocal fold motion, suggesting the need for the development of children-specific kinematic norms. Results suggest more uncontrolled vibratory motion in children, reflecting changes in the vocal fold layered structure and aero-acoustic source mechanisms.

  15. Parallel optical control of spatiotemporal neuronal spike activity using high-speed digital light processing.

    PubMed

    Jerome, Jason; Foehring, Robert C; Armstrong, William E; Spain, William J; Heck, Detlef H

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz-glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales.

  16. Parallel Optical Control of Spatiotemporal Neuronal Spike Activity Using High-Speed Digital Light Processing

    PubMed Central

    Jerome, Jason; Foehring, Robert C.; Armstrong, William E.; Spain, William J.; Heck, Detlef H.

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz–glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales. PMID:21904526

  17. High-speed parallel phase-shifting digital holography system using special-purpose computer for image reconstruction

    NASA Astrophysics Data System (ADS)

    Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2015-05-01

    We report a high-speed parallel phase-shifting digital holography system using a special-purpose computer for image reconstruction. Parallel phase-shifting digital holography is a technique capable of single-shot phase-shifting interferometry. This technique records information of multiple phase-shifted holograms required for calculation of phase-shifting interferometry with a single shot by using space-division multiplexing. This technique needs image-reconstruction process for a huge amount of recorded holograms. In particular, it takes a long time to calculate light propagation based on fast Fourier transform in the process and to obtain a motion picture of a dynamically and fast moving object. Then we designed a special-purpose computer for accelerating the image-reconstruction process of parallel phase-shifting digital holography. We developed a special-purpose computer consisting of VC707 evaluation kit (Xilinx Inc.) which is a field programmable gate array board. We also recorded holograms consisting of 128 × 128 pixels at a frame rate of 180,000 frames per second by the constructed parallel phase-shifting digital holography system. By applying the developed computer to the recorded holograms, we confirmed that the designed computer can accelerate the calculation of image-reconstruction process of parallel phase-shifting digital holography ~50 times faster than a CPU.

  18. Mapping and delineating wetlands of Huntington Wildlife Forest using very high resolution digital color-infrared imagery

    NASA Astrophysics Data System (ADS)

    Yavuz, Mehmet

    The effectiveness of off-site wetland delineation methods using very high resolution digital color-infrared aerial imagery (the color-IR imagery) is compared to the traditional on-site wetland delineation method. The on-site delineation results created using the US Fish and Wildlife Service's National Wetland Inventory (NWI map procedures are compared to the following mapping techniques; heads-up digitizing, hybrid classification, Normalized Difference Vegetation Index (NDVI) and unsupervised classifications (ISODATA) using the same image source. Each of the mapping techniques was applied using the seasonal color-IR imagery. Pair-wise significance tests of the closest mean distances indicated that heads-up digitizing was significantly more accurate than other classification techniques for the color-IR imagery. A combination of the heads-up digitizing and the hybrid classification showed that emergent wetland and scrub-shrub wetlands can be delineated without visiting the ground from the color-IR imagery. Applying logarithmic and hyperbolic sine algorithms to enhance the radiometric property of the color-IR imagery increased delineation accuracy 98% in the spring color-IR imagery and 28% in the fall color-IR imagery. Methods for measuring the accuracy of linear features are reviewed and a new method Points-in-Buffer Analysis (PIBA) is proposed. Keywords. Wetland boundary delineation, heads-up digitizing, radiometric enhancement, wetland boundary accuracy, point-in-buffer analysis (PIBA)

  19. A high speed CMOS image sensor with a novel digital correlated double sampling and a differential difference amplifier.

    PubMed

    Kim, Daehyeok; Bae, Jaeyoung; Song, Minkyu

    2015-03-02

    In order to increase the operating speed of a CMOS image sensor (CIS), a new technique of digital correlated double sampling (CDS) is described. In general, the fixed pattern noise (FPN) of a CIS has been reduced with the subtraction algorithm between the reset signal and pixel signal. This is because a single-slope analog-to-digital converter (ADC) has been normally adopted in the conventional digital CDS with the reset ramp and signal ramp. Thus, the operating speed of a digital CDS is much slower than that of an analog CDS. In order to improve the operating speed, we propose a novel digital CDS based on a differential difference amplifier (DDA) that compares the reset signal and the pixel signal using only one ramp. The prototype CIS has been fabricated with 0.13 µm CIS technology and it has the VGA resolution of 640 × 480. The measured conversion time is 16 µs, and a high frame rate of 131 fps is achieved at the VGA resolution.

  20. Applications and Innovations for Use of High Definition and High Resolution Digital Motion Imagery in Space Operations

    NASA Technical Reports Server (NTRS)

    Grubbs, Rodney

    2016-01-01

    The first live High Definition Television (HDTV) from a spacecraft was in November, 2006, nearly ten years before the 2016 SpaceOps Conference. Much has changed since then. Now, live HDTV from the International Space Station (ISS) is routine. HDTV cameras stream live video views of the Earth from the exterior of the ISS every day on UStream, and HDTV has even flown around the Moon on a Japanese Space Agency spacecraft. A great deal has been learned about the operations applicability of HDTV and high resolution imagery since that first live broadcast. This paper will discuss the current state of real-time and file based HDTV and higher resolution video for space operations. A potential roadmap will be provided for further development and innovations of high-resolution digital motion imagery, including gaps in technology enablers, especially for deep space and unmanned missions. Specific topics to be covered in the paper will include: An update on radiation tolerance and performance of various camera types and sensors and ramifications on the future applicability of these types of cameras for space operations; Practical experience with downlinking very large imagery files with breaks in link coverage; Ramifications of larger camera resolutions like Ultra-High Definition, 6,000 [pixels] and 8,000 [pixels] in space applications; Enabling technologies such as the High Efficiency Video Codec, Bundle Streaming Delay Tolerant Networking, Optical Communications and Bayer Pattern Sensors and other similar innovations; Likely future operations scenarios for deep space missions with extreme latency and intermittent communications links.

  1. Electrochemically Synthesized Sb/Sb2O3 Composites as High-Capacity Anode Materials Utilizing a Reversible Conversion Reaction for Na-Ion Batteries.

    PubMed

    Hong, Kyung-Sik; Nam, Do-Hwan; Lim, Sung-Jin; Sohn, DongRak; Kim, Tae-Hee; Kwon, HyukSang

    2015-08-12

    Sb/Sb2O3 composites are synthesized by a one-step electrodeposition process from an aqueous electrolytic bath containing a potassium antimony tartrate complex. The synthesis process involves the electrodeposition of Sb simultaneously with the chemical deposition of Sb2O3, which allows for the direct deposition of morula-like Sb/Sb2O3 particles on the current collector without using a binder. Structural characterization confirms that the Sb/Sb2O3 composites are composed of approximately 90 mol % metallic Sb and 10 mol % crystalline Sb2O3. The composite exhibits a high reversible capacity (670 mAh g(-1)) that is higher than the theoretical capacity of Sb (660 mAh g(-1)). The high reversible capacity results from the conversion reaction between Na2O and Sb2O3 that occurs additionally to the alloying/dealloying reaction of Sb with Na. Moreover, the Sb/Sb2O3 composite shows excellent cycle performance with 91.8% capacity retention over 100 cycles, and a superior rate capability of 212 mAh g(-1) at a high current density of 3300 mA g(-1). The outstanding cycle performance is attributed to an amorphous Na2O phase generated by the conversion reaction, which inhibits agglomeration of Sb particles and acts as an effective buffer against volume change of Sb during cycling.

  2. THEMIS high-resolution digital terrain: Topographic and thermophysical mapping of Gusev Crater, Mars

    USGS Publications Warehouse

    Cushing, G.E.; Titus, T.N.; Soderblom, L.A.; Kirk, R.L.

    2009-01-01

    We discuss a new technique to generate high-resolution digital terrain models (DTMs) and to quantitatively derive and map slope-corrected thermophysical properties such as albedo, thermal inertia, and surface temperatures. This investigation is a continuation of work started by Kirk et al. (2005), who empirically deconvolved Thermal Emission Imaging System (THEMIS) visible and thermal infrared data of this area, isolating topographic information that produced an accurate DTM. Surface temperatures change as a function of many variables such as slope, albedo, thermal inertia, time, season, and atmospheric opacity. We constrain each of these variables to construct a DTM and maps of slope-corrected albedo, slope- and albedo-corrected thermal inertia, and surface temperatures across the scene for any time of day or year and at any atmospheric opacity. DTMs greatly facilitate analyses of the Martian surface, and the MOLA global data set is not finely scaled enough (128 pixels per degree, ???0.5 km per pixel near the equator) to be combined with newer data sets (e.g., High Resolution Imaging Science Experiment, Context Camera, and Compact Reconnaissance Imaging Spectrometer for Mars at ???0.25, ???6, and ???20 m per pixel, respectively), so new techniques to derive high-resolution DTMs are always being explored. This paper discusses our technique of combining a set of THEMIS visible and thermal infrared observations such that albedo and thermal inertia variations within the scene are eliminated and only topographic variations remain. This enables us to produce a high-resolution DTM via photoclinometry techniques that are largely free of albedo-induced errors. With this DTM, THEMIS observations, and a subsurface thermal diffusion model, we generate slope-corrected maps of albedo, thermal inertia, and surface temperatures. In addition to greater accuracy, these products allow thermophysical properties to be directly compared with topography.

  3. Rotational IMRT delivery using a digital linear accelerator in very high dose rate 'burst mode'

    NASA Astrophysics Data System (ADS)

    Salter, Bill J.; Sarkar, Vikren; Wang, Brian; Shukla, Himanshu; Szegedi, Martin; Rassiah-Szegedi, Prema

    2011-04-01

    Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units per minute (MU min-1) high dose rate bursts of dose are facilitated by a flattening-filter-free treatment beam on a Siemens Artiste (Oncology Care Systems, Siemens Medical Solutions, Concord, CA, USA) digital linear accelerator in a non-clinical configuration. Burst mode delivery differs from continuous mode delivery, used by Elekta's VMAT (Elekta Ltd, Crawley, UK) and Varian's RapidArc (Varian Medical Systems, Palo Alto, CA, USA) implementations, in that dose is not delivered while MLC leaves are moving. Instead, dose is delivered in bursts over very short arc angles and only after an MLC segment shape has been completely formed and verified by the controller. The new system was confirmed to be capable of delivering a wide array of clinically relevant treatment plans, without machine fault or other delivery anomalies. Dosimetric accuracy of the modulated arc platform, as well as the Prowess (Prowess Inc., Concord, CA, USA) prototype treatment planning version utilized here, was quantified and confirmed, and delivery times were measured as significantly brief, even with large hypofractionated doses. The burst mode modulated arc approach evaluated here appears to represent a capable, accurate and efficient delivery approach.

  4. Low complexity digital backpropagation for high baud subcarrier-multiplexing systems.

    PubMed

    Zhang, Fangyuan; Zhuge, Qunbi; Qiu, Meng; Plant, David V

    2016-07-25

    In this paper, we propose two modifications to reduce the complexity of the subcarrier-multiplexing (SCM) based digital backpropagation (DBP) for high symbol rate SCM systems. The first one is to reduce the number of interfering subcarriers (RS-SCM-DBP) when evaluating the cross-subcarrier nonlinearity (CSN). The second one is to replace the original frequency domain CSN filters with the infinite impulse response (IIR) filters (IIR-RS-SCM-DBP) in the CSN compensation. The performance of the proposed schemes are numerically evaluated in three-channel dual-polarization (DP) 16QAM wavelength-division multiplexing (WDM) transmissions. The aggregate symbol rate for each channel is 120 GBaud and the transmission distance is 1600 km. For the SCM system with 16 subcarriers, the IIR-RS-SCM-DBP with only 4 interfering subcarriers and 2 steps can achieve a 0.3 dB Q-factor improvement in the WDM transmission. Compared to the original SCM-DBP, the proposed IIR-RS-SCM-DBP reduces the complexity by 48% at a performance loss of only 0.07 dB.

  5. Recording High Resolution 3D Lagrangian Motions In Marine Dinoflagellates using Digital Holographic Microscopic Cinematography

    NASA Astrophysics Data System (ADS)

    Sheng, J.; Malkiel, E.; Katz, J.; Place, A. R.; Belas, R.

    2006-11-01

    Detailed data on swimming behavior and locomotion for dense population of dinoflagellates constitutes a key component to understanding cell migration, cell-cell interactions and predator-prey dynamics, all of which affect algae bloom dynamics. Due to the multi-dimensional nature of flagellated cell motions, spatial-temporal Lagrangian measurements of multiple cells in high concentration are very limited. Here we present detailed data on 3D Lagrangian motions for three marine dinoflagellates: Oxyrrhis marina, Karlodinium veneficum, and Pfiesteria piscicida, using digital holographic microscopic cinematography. The measurements are performed in a 5x5x25mm cuvette with cell densities varying from 50,000 ˜ 90,000 cells/ml. Approximately 200-500 cells are tracked simultaneously for 12s at 60fps in a sample volume of 1x1x5 mm at a spatial resolution of 0.4x0.4x2 μm. We fully resolve the longitudinal flagella (˜200nm) along with the Lagrangian trajectory of each organism. Species dependent swimming behavior are identified and categorized quantitatively by velocities, radii of curvature, and rotations of pitch. Statistics on locomotion, temporal & spatial scales, and diffusion rate show substantial differences between species. The scaling between turning radius and cell dimension can be explained by a distributed stokeslet model for a self-propelled body.

  6. A Seamless, High-Resolution, Coastal Digital Elevation Model (DEM) for Southern California

    USGS Publications Warehouse

    Barnard, Patrick L.; Hoover, Daniel

    2010-01-01

    A seamless, 3-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the 20-m elevation contour. This dataset was produced to provide critical boundary conditions (bathymetry and topography) for a modeling effort designed to predict the impacts of severe winter storms on the Southern California coast (Barnard and others, 2009). The hazards model, run in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable detailed prediction of water levels, run-up, wave heights, and currents. Research-grade predictions of coastal flooding, inundation, erosion, and cliff failure are also included. The DEM was constructed to define the general shape of nearshore, beach and cliff surfaces as accurately as possible, with less emphasis on the detailed variations in elevation inland of the coast and on bathymetry inside harbors. As a result this DEM should not be used for navigation purposes.

  7. Rotational IMRT delivery using a digital linear accelerator in very high dose rate 'burst mode'.

    PubMed

    Salter, Bill J; Sarkar, Vikren; Wang, Brian; Shukla, Himanshu; Szegedi, Martin; Rassiah-Szegedi, Prema

    2011-04-07

    Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units per minute (MU min(-1)) high dose rate bursts of dose are facilitated by a flattening-filter-free treatment beam on a Siemens Artiste (Oncology Care Systems, Siemens Medical Solutions, Concord, CA, USA) digital linear accelerator in a non-clinical configuration. Burst mode delivery differs from continuous mode delivery, used by Elekta's VMAT (Elekta Ltd, Crawley, UK) and Varian's RapidArc (Varian Medical Systems, Palo Alto, CA, USA) implementations, in that dose is not delivered while MLC leaves are moving. Instead, dose is delivered in bursts over very short arc angles and only after an MLC segment shape has been completely formed and verified by the controller. The new system was confirmed to be capable of delivering a wide array of clinically relevant treatment plans, without machine fault or other delivery anomalies. Dosimetric accuracy of the modulated arc platform, as well as the Prowess (Prowess Inc., Concord, CA, USA) prototype treatment planning version utilized here, was quantified and confirmed, and delivery times were measured as significantly brief, even with large hypofractionated doses. The burst mode modulated arc approach evaluated here appears to represent a capable, accurate and efficient delivery approach.

  8. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2001-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which con lead to a loss of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in highspeed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  9. Comparison on different insects' wing displacements using high speed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Aguayo, Daniel D.; Santoyo, Fernando Mendoza; de La Torre-I, Manuel H.; Salas-Araiza, Manuel D.; Caloca-Mendez, Cristian

    2011-06-01

    In-flight insect wing motion behavior depends on a wide variety of conditions. They have a complex structural system and what seems to be a rather complicated motion. Researchers in many fields have endeavoured to study and reproduce these wing movements with the aim to apply the gained knowledge in their fields and for the benefit of avionic technological improvements and insect migration studies, among many other themes. The study of in-flight insect wing motion and its measurement is a relevant issue to understand and reproduce its functionality. Being capable of measuring the wing flapping using optical noninvasive methods adds scientific and technological value to the fundamental research in the area. Four different types of butterflies found widely in Mexico's forests are used to compare their wing flapping mechanisms. An out-of-plane digital holographic interferometry system is used to detect and measure its wingmicro deformations. Displacement changes from in vivo flapping wings are registered with a CMOS high speed camera yielding full field of view images depicting these insects' wing motion. The results have a resolution in the scale of hundreds of nanometers over the entire wing surface.

  10. Comparison on different insects' wing displacements using high speed digital holographic interferometry.

    PubMed

    Aguayo, Daniel D; Santoyo, Fernando Mendoza; De la Torre-I, Manuel H; Salas-Araiza, Manuel D; Caloca-Mendez, Cristian

    2011-06-01

    In-flight insect wing motion behavior depends on a wide variety of conditions. They have a complex structural system and what seems to be a rather complicated motion. Researchers in many fields have endeavoured to study and reproduce these wing movements with the aim to apply the gained knowledge in their fields and for the benefit of avionic technological improvements and insect migration studies, among many other themes. The study of in-flight insect wing motion and its measurement is a relevant issue to understand and reproduce its functionality. Being capable of measuring the wing flapping using optical noninvasive methods adds scientific and technological value to the fundamental research in the area. Four different types of butterflies found widely in Mexico's forests are used to compare their wing flapping mechanisms. An out-of-plane digital holographic interferometry system is used to detect and measure its wingmicro deformations. Displacement changes from in vivo flapping wings are registered with a CMOS high speed camera yielding full field of view images depicting these insects' wing motion. The results have a resolution in the scale of hundreds of nanometers over the entire wing surface.

  11. High-Speed Optical Library System Using Digital Versatile Disk Random Access Memory

    NASA Astrophysics Data System (ADS)

    Tanabe, Takaya; Ura, Tetsu; Yamamoto, Manabu

    2000-02-01

    A high-data-transfer-rate optical storage system using a redundant array of inexpensive libraries (RAIL) has been developed and tested. It incorporates multiple libraries, where each library consists of dual digital versatile disk (DVD) random access memory (RAM) drives and a single robotic hand and holds 2.6 GB DVD disks. To increase the reliability of data storage and at the same time to eliminate the need for read-after-write verification, which doubles the recording time, a redundant array of inexpensive drives (RAID) 4 algorithm is implemented in the control unit of the storage system. Data sent by the host is transferred to a control unit, which stripes the data into five data groups plus one parity unit. The striped and parity data is sent to individual libraries and written to the DVD disks. This system writes and retrieves data with a transfer rate of approximately 6 MB/s, using write and read control methods that minimize the data striping overhead. This reliable library system can be used for networked multimedia applications.

  12. Spatial disaggregation of satellite-derived irradiance using a high-resolution digital elevation model

    SciTech Connect

    Ruiz-Arias, Jose A.; Tovar-Pescador, Joaquin; Cebecauer, Tomas; Suri, Marcel

    2010-09-15

    Downscaling of the Meteosat-derived solar radiation ({proportional_to}5 km grid resolution) is based on decomposing the global irradiance and correcting the systematic bias of its components using the elevation and horizon shadowing that are derived from the SRTM-3 digital elevation model (3 arc sec resolution). The procedure first applies the elevation correction based on the difference between coarse and high spatial resolution. Global irradiance is split into direct, diffuse circumsolar and diffuse isotropic components using statistical models, and then corrections due to terrain shading and sky-view fraction are applied. The effect of reflected irradiance is analysed only in the theoretical section. The method was applied in the eastern Andalusia, Spain, and the validation was carried out for 22 days on April, July and December 2006 comparing 15-min estimates of the satellite-derived solar irradiance and observations from nine ground stations. Overall, the corrections of the satellite estimates in the studied region strongly reduced the mean bias of the estimates for clear and cloudy days from roughly 2.3% to 0.4%. (author)

  13. Digital high-pass filter deconvolution by means of an infinite impulse response filter

    NASA Astrophysics Data System (ADS)

    Födisch, P.; Wohsmann, J.; Lange, B.; Schönherr, J.; Enghardt, W.; Kaever, P.

    2016-09-01

    In the application of semiconductor detectors, the charge-sensitive amplifier is widely used in front-end electronics. The output signal is shaped by a typical exponential decay. Depending on the feedback network, this type of front-end electronics suffers from the ballistic deficit problem, or an increased rate of pulse pile-ups. Moreover, spectroscopy applications require a correction of the pulse-height, while a shortened pulse-width is desirable for high-throughput applications. For both objectives, digital deconvolution of the exponential decay is convenient. With a general method and the signals of our custom charge-sensitive amplifier for cadmium zinc telluride detectors, we show how the transfer function of an amplifier is adapted to an infinite impulse response (IIR) filter. This paper investigates different design methods for an IIR filter in the discrete-time domain and verifies the obtained filter coefficients with respect to the equivalent continuous-time frequency response. Finally, the exponential decay is shaped to a step-like output signal that is exploited by a forward-looking pulse processing.

  14. Application of a sensitivity analysis technique to high-order digital flight control systems

    NASA Technical Reports Server (NTRS)

    Paduano, James D.; Downing, David R.

    1987-01-01

    A sensitivity analysis technique for multiloop flight control systems is studied. This technique uses the scaled singular values of the return difference matrix as a measure of the relative stability of a control system. It then uses the gradients of these singular values with respect to system and controller parameters to judge sensitivity. The sensitivity analysis technique is first reviewed; then it is extended to include digital systems, through the derivation of singular-value gradient equations. Gradients with respect to parameters which do not appear explicitly as control-system matrix elements are also derived, so that high-order systems can be studied. A complete review of the integrated technique is given by way of a simple example: the inverted pendulum problem. The technique is then demonstrated on the X-29 control laws. Results show linear models of real systems can be analyzed by this sensitivity technique, if it is applied with care. A computer program called SVA was written to accomplish the singular-value sensitivity analysis techniques. Thus computational methods and considerations form an integral part of many of the discussions. A user's guide to the program is included. The SVA is a fully public domain program, running on the NASA/Dryden Elxsi computer.

  15. High-resolution image digitizing through 12x3-bit RGB-filtered CCD camera

    NASA Astrophysics Data System (ADS)

    Cheng, Andrew Y. S.; Pau, Michael C. Y.

    1996-09-01

    A high resolution computer-controlled CCD image capturing system is developed by using a 12 bits 1024 by 1024 pixels CCD camera and motorized RGB filters to grasp an image with color depth up to 36 bits. The filters distinguish the major components of color and collect them separately while the CCD camera maintains the spatial resolution and detector filling factor. The color separation can be done optically rather than electronically. The operation is simply by placing the capturing objects like color photos, slides and even x-ray transparencies under the camera system, the necessary parameters such as integration time, mixing level and light intensity are automatically adjusted by an on-line expert system. This greatly reduces the restrictions of the capturing species. This unique approach can save considerable time for adjusting the quality of image, give much more flexibility of manipulating captured object even if it is a 3D object with minimal setup fixers. In addition, cross sectional dimension of a 3D capturing object can be analyzed by adapting a fiber optic ring light source. It is particularly useful in non-contact metrology of a 3D structure. The digitized information can be stored in an easily transferable format. Users can also perform a special LUT mapping automatically or manually. Applications of the system include medical images archiving, printing quality control, 3D machine vision, and etc.

  16. Achieving high-resolution in flat-panel imagers for digital radiography

    NASA Astrophysics Data System (ADS)

    Rahn, Jeffrey T.; Lemmi, Francesco; Lu, Jeng-Ping; Mei, Ping; Street, Robert A.; Ready, Steve E.; Ho, Jackson; Apte, Raj B.; Van Schuylenbergh, Koenraad; Lau, Rachel; Weisfield, Richard L.; Lujan, Rene; Boyce, James B.

    1999-10-01

    Amorphous silicon (a-Si:H) matrix-addressed imager sensors are the leading new technology for digital medical x-ray imaging. Large-area systems are now commercially available with good resolution and large dynamic range. These systems image x-rays either by detecting light emission from a phosphor screen onto an a-Si:H photodiode, or by collecting ionization charge in a thick x-ray absorbing photoconductor with as selenium, and both approaches have been widely discussed in the literature. While these systems meet the performance needs for general radiographic imaging, further improvements in sensitivity, noise and resolution are needed to fully satisfy the requirements for fluoroscopy and mammography. The approach taken for this paper uses indirect detection, with a phosphor layer for x-ray conversion. The thin a-Si:H photodiode layer for detects the scintillation light. In contrast with the present generation of devices, which have a mesa-isolated sensor at each pixel, these imagers use a continuous sensor covering the entire front surface of the array. The p+ and i layers of a-Si:H are continuous, while the n+ contact has been patterned to isolate adjacent pixels. The continuous photodiode layer maximizes light absorption from the phosphor and provides high x-ray conversion efficiency.

  17. Method and apparatus for analog signal conditioner for high speed, digital x-ray spectrometer

    DOEpatents

    Warburton, W.K.; Hubbard, B.

    1999-02-09

    A signal processing system which accepts input from an x-ray detector-preamplifier and produces a signal of reduced dynamic range for subsequent analog-to-digital conversion is disclosed. The system conditions the input signal to reduce the number of bits required in the analog-to-digital converter by removing that part of the input signal which varies only slowly in time and retaining the amplitude of the pulses which carry information about the x-rays absorbed by the detector. The parameters controlling the signal conditioner`s operation can be readily supplied in digital form, allowing it to be integrated into a feedback loop as part of a larger digital x-ray spectroscopy system. 13 figs.

  18. Method and apparatus for analog signal conditioner for high speed, digital x-ray spectrometer

    DOEpatents

    Warburton, William K.; Hubbard, Bradley

    1999-01-01

    A signal processing system which accepts input from an x-ray detector-preamplifier and produces a signal of reduced dynamic range for subsequent analog-to-digital conversion. The system conditions the input signal to reduce the number of bits required in the analog-to-digital converter by removing that part of the input signal which varies only slowly in time and retaining the amplitude of the pulses which carry information about the x-rays absorbed by the detector. The parameters controlling the signal conditioner's operation can be readily supplied in digital form, allowing it to be integrated into a feedback loop as part of a larger digital x-ray spectroscopy system.

  19. Increased gene expression of catecholamine-synthesizing enzymes in adrenal glands contributes to high circulating catecholamines in pigs with tachycardia-induced cardiomyopathy.

    PubMed

    Tomaszek, A; Kiczak, L; Bania, J; Paslawska, U; Zacharski, M; Janiszewski, A; Noszczyk-Nowak, A; Dziegiel, P; Kuropka, P; Ponikowski, P; Jankowska, E A

    2015-04-01

    High levels of circulating catecholamines have been established as fundamental pathophysiological elements of heart failure (HF). However, it is unclear whether the increased gene expression of catecholamine-synthesis enzymes in the adrenal glands contributes to these hormone abnormalities in large animal HF models. We analyzed the mRNA levels of catecholamine-synthesizing enzymes: tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AAAD), dopamine-β-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in adrenal glands of 18 pigs with chronic systolic non-ischaemic HF (tachycardia-induced cardiomyopathy due to right ventricle pacing) and 6 sham-operated controls. Pigs with severe HF demonstrated an increased expression of TH and DBH (but neither AAAD nor PNMT) as compared to animals with milder HF and controls (P<0.05 in all cases). The increased adrenal mRNA expression of TH and DBH was accompanied by a reduced left ventricle ejection fraction (LVEF) (P<0.001) and an elevated plasma B-type natriuretic peptide (BNP) (P<0.01), the other indices reflecting HF severity. There was a positive relationship between the increased adrenal mRNA expression of TH and DBH, and the high levels of circulating adrenaline and noradrenaline (all P<0.05). The association with noradrenaline remained significant also when adjusted for LVEF and plasma BNP, suggesting a significant contribution of adrenals to the circulating pool of catecholamines in subjects with systolic HF.

  20. All-into-one strategy to synthesize mesoporous hybrid silicate microspheres from naturally rich red palygorskite clay as high-efficient adsorbents

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Tian, Guangyan; Wang, Dandan; Zhang, Zhifang; Kang, Yuru; Zong, Li; Wang, Aiqin

    2016-12-01

    A mesoporous hybrid silicate microsphere with superior adsorption performance has been successfully synthesized by employing an “all-into-one” strategy and a simple one-pot hydrothermal process using naturally abundant low-grade red palygorskite (PAL) clay as raw material in the presence of non-toxic SiO32‑ and Mg2+ ions. As is expected, both the PAL and associated minerals transformed into a new amorphous mesoporous hybrid silicate microsphere without using any additional pore-forming template. The mesoporous silicate microsphere shows a large pore size of 37.74 nm, high specific surface area of 489.81 m2/g (only 54.67 m2/g for raw PAL) and negative surface potential of ‑43.3 mV, and its maximum adsorption capabilities for Methylene bule (MB) and Crystal violet (CV) reach 407.95 mg/g and 397.22 mg/g, respectively. Meanwhile, 99.8% of MB (only 53% for raw PAL) and 99.7% of CV (only 43% for raw PAL) were sucessfully removed from 200 mg/L of initial dye solution by only using 1 g/L of the adsorbent. In addition, the spent adsorbent can be easily regenerated and repeatly reused for muptiple cycles. The study on adsorption mechanism revealed that electrostatic attraction, hydrogen bonding and chemical complexing interactions are the main factors contributed to the high dye adsorption.

  1. High frequency dielectric response and magnetic studies of Zn1-xTbxFe2O4 nanocrystalline ferrites synthesized via micro-emulsion technique

    NASA Astrophysics Data System (ADS)

    Azhar Khan, Muhammad; Sabir, Muhammad; Mahmood, Azhar; Asghar, M.; Mahmood, K.; Afzal Khan, M.; Ahmad, Iqbal; Sher, Muhammad; Farooq Warsi, Muhammad

    2014-06-01

    Tb3+-doped nanocrystalline zinc ferrites with a nominal composition of Zn1-xTbxFe2O4 (x=0, 0.03, 0.06, 0.09, 0.12 and 0.15) were prepared by micro-emulsion method and were annealed at 600 °C for 8.5 h. The synthesized samples were characterized by thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and dielectric measurement techniques. The powder XRD patterns confirm the single phase cubic spinel structure, indicated that doping nanoferrites with small concentrations of terbium ions allowed their entrance to the spinel lattice and the crystallite size is found in the range of 16-24 nm. The dielectric constant (ε) and dielectric loss (tanδ) of all the samples were measured in the frequency range 100 MHz-3 GHz at room temperature. The dielectric constant and dielectric loss of the samples are found to decrease with increase in frequency and Tb3+ content. The reduction in the dielectric parameters is attributed to the obstruction incorporated in electron exchange mechanism caused by the lockup among iron and terbium cations. The magnetic properties revealed that these terbium doped nanocrystalline zinc ferrites exhibit ferrimagnetic behavior. The high saturation magnetization and coercivity along with smaller dielectric parameters having Tb-contents suggests that the materials are suitable for applications in memory devices and high frequency applications.

  2. First-principles study of the new compounds CrGa2Sb2 and CrGaSb synthesized under high pressure

    NASA Astrophysics Data System (ADS)

    Kulatov, E.; Magnitskaya, M.; Maksimov, E.; Titov, A.; Uspenskii, Yu.

    2011-10-01

    We present the density-functional calculations of the compounds CrGa2Sb2 and CrGaSb synthesized recently under high pressure. Calculation reproduces well all details of the crystal structure of these compounds, their spin ordering, and a larger metallicity of CrGaSb comparing to CrGa2Sb2. Particular attention is given to the room temperature ferromagnetic compound CrGa2Sb2, where the huge resistivity hinting at the possible semiconducting properties was measured. To understand the mechanism of its anisotropic conductivity, we analyze the band structure, calculated kinetic and optical characteristics of this compound. It is found that the density of states of CrGa2Sb2 has a pseudogap near the Fermi level, where the Cr atoms do not dominate, but contribute even less than the atoms of Ga and Sb. This explains a very high calculated resistivity of CrGa2Sb2, which can be characterized as a ferromagnetic compound with a low metallic conductivity. This type of conductivity remains unchanged, when a possible Cr-deficiency of CrGa2Sb2 is taken into account or the MBJ-LDA exchange-correlation potential is used instead of the GGA-LDA one in calculation. The potential of this compound for the development of spintronic materials is discussed.

  3. TiO2 film decorated with highly dispersed polyoxometalate nanoparticles synthesized by micelle directed method for the efficiency enhancement of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    He, Lifei; Chen, Li; Zhao, Yue; Chen, Weilin; Shan, Chunhui; Su, Zhongmin; Wang, Enbo

    2016-10-01

    In this work, two kinds of polyoxometalate (POM) nanoparticles with controlled shapes and structures were synthesized by micelle directed method and then composited with TiO2 via calcination to remove the surfactants owing to the excellent electronic storage and transmission ability of POM, finally obtaining two kinds of TiO2 composites with highly dispersed and small-sized POM nanoparticles (∼1 nm). The TiO2 composites were then induced into the photoanodes of dye-sensitized (N719) solar cells (DSSCs). The separation of electron-holes becomes more favorable due to the nanostructure and high dispersion of POM which provide more active sites than pure POM tending to agglomeration. The TiO2 composite photoanodes finally yielded the power conversion efficiency (PCE) of 8.4% and 8.2%, respectively, which were 42% and 39% higher than the pristine TiO2 based anodes. In addition, the mechanisms of POM in DSSC are proposed.

  4. Highly oriented diamond (111) films synthesized by pulse bias-enhanced nucleation and epitaxial grain selection on a 3C-SiC/Si (111) substrate

    NASA Astrophysics Data System (ADS)

    Suto, Takeru; Yaita, Junya; Iwasaki, Takayuki; Hatano, Mutsuko

    2017-02-01

    We report the synthesis of highly oriented diamond (HOD) (111) films on 3C-SiC/Si (111) substrates. Bias-enhanced nucleation (BEN) is a key process for the heteroepitaxial growth of HOD films. Conventional long nucleation periods have been found to lead to a polycrystalline diamond film on the 3C-SiC (111) surface. Here, we propose a method that combines brief BEN (<30 s), called pulse BEN, and epitaxial grain selection by oxidative etching. Smaller diamond nuclei with a higher spatial density on the substrate were formed by pulse BEN with a pulse duration of <30 s. We found that precisely controlling the pulse duration is important for obtaining a nucleation density that is sufficiently high to obtain the HOD films. By adding oxygen gas to the subsequent growth process, non-epitaxial nuclei were removed and epitaxial diamond grains selectively remained. There was no notable difference in the relative growth rate of [111] to [100] with and without oxygen, and the orientation improvement was observed on both the (100) and (111) substrates. This suggests that the mechanism of oxidative removal was not evolutionary selective growth, but etching of the non-epitaxial interfaces between the nuclei and the (111) substrate. Finally, the HOD (111) films covering the entire 3C-SiC surface were synthesized, and they exhibited distinct diffraction spots, indicating the formation of the oriented diamond.

  5. Bridged bis(amidinate) ytterbium alkoxide and phenoxide: syntheses, structures, and their high activity for controlled polymerization of L-lactide and epsilon-caprolactone.

    PubMed

    Wang, Junfeng; Yao, Yingming; Zhang, Yong; Shen, Qi

    2009-01-19

    Bridged bis(amidinate) ytterbium alkoxide and phenoxide with diverse molecular structures were synthesized in high yields and confirmed by X-ray crystal structural analysis. The reaction of LYbCl(THF)(2) (L = Me(3)SiNC(Ph)N(CH(2))(3)NC(Ph)NSiMe(3)) with 1 equiv of NaOAr (ArO = 2,6-diisopropylphenoxo) afforded the mononuclear complex LYb(OAr)DME 1 with a seven-coordinated ytterbium atom surrounded by one chelating bis(amidinate) ligand, one phenoxo group, and one DME (dimethoxyethane) molecule. The same reaction with 1 equiv of NaO(i)Pr yielded the binuclear complex Yb(mu(2)-L)(2)(mu(2)-O(i)Pr)(2)Yb, 2, with two equivalent six-coordinate metal centers connected by two linked bis(amidinate)s and two O(i)Pr bridges formed via a ligand redistribution reaction that occurred during the metathesis reaction. Both 1 and 2 initiated the ring-opening polymerization of L-lactide, as well as epsilon-caprolactone (epsilon-CL), in a controlled manner with high reactivity, as indicated by a linear relationship between M(n) and conversion and by narrow molecular weight distributions (PDI = 1.15-1.25) up to 100% conversion. The differences in catalytic performance between complexes 1 and 2 are discussed.

  6. High accuracy measurement of unsteady flows using digital particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Funes-Gallanzi, M.

    1998-09-01

    The analysis of digital PIV data, either derived from CCD technology or through film and then scanned, typically involves two quantization steps: spatial and intensity quantization. The all-optical systems do not introduce these sources of error. For systems which make use of digital technology however, it is of crucial importance to have reliable error bounds and a sufficiently accurate estimate of particle position, taking into consideration both types of quantization. The accuracy demanded by aerodynamicists from PIV has been a major barrier to its practical application in the past. The more recent approach of using the Gaussian profile of the particle images to yield sub-pixel accurate position estimates has resulted in robust measurements being taken to an accuracy of 1/10th pixel and 1% in velocity for the in-plane velocity, in hostile industrial environments. A major problem for 3D PIV estimation has historically been that the out-of-plane velocity error was of the order of 3-4 times larger than in-plane. The out-of-plane velocity estimate can be derived from the change in the ratio of amplitude to variance—known as the depth factor—of the Gaussian form, as a particle traverses the beam profile. However, such measurements are crucially dependent not only on an accurate position estimate but also on an equally accurate estimate of the amplitude and variance. The accuracy of the Gaussian profile fit using a Nelder-Meade optimisation method as developed until now however, is not capable of providing the required accuracies. Therefore, this paper presents a development of the "locales" approach to position estimation to achieve the desired objective of high accuracy PIV measurements. This approach makes use of the fact that by considering all the possible digital representations of the Gaussian particle profile, regions of indistinguishable position can be derived. These positions are referred to as "locales". By considering the density, distribution, and

  7. Development and application of a high speed digital data acquisition technique to study steam bubble collapse using particle image velocimetry

    SciTech Connect

    Schmidl, W.D.

    1992-08-01

    The use of a Particle Image Velocimetry (PIV) method, which uses digital cameras for data acquisition, for studying high speed fluid flows is usually limited by the digital camera's frame acquisition rate. The velocity of the fluid under study has to be limited to insure that the tracer seeds suspended in the fluid remain in the camera's focal plane for at least two consecutive images. However, the use of digital cameras for data acquisition is desirable to simplify and expedite the data analysis process. A technique was developed which will measure fluid velocities with PIV techniques using two successive digital images and two different framing rates simultaneously. The first part of the method will measure changes which occur to the flow field at the relatively slow framing rate of 53.8 ms. The second part will measure changes to the same flow field at the relatively fast framing rate of 100 to 320 [mu]s. The effectiveness of this technique was tested by studying the collapse of steam bubbles in a subcooled tank of water, a relatively high speed phenomena. The tracer particles were recorded and velocity vectors for the fluid were obtained far from the steam bubble collapse.

  8. Development and application of a high speed digital data acquisition technique to study steam bubble collapse using particle image velocimetry

    SciTech Connect

    Schmidl, W.D.

    1992-08-01

    The use of a Particle Image Velocimetry (PIV) method, which uses digital cameras for data acquisition, for studying high speed fluid flows is usually limited by the digital camera`s frame acquisition rate. The velocity of the fluid under study has to be limited to insure that the tracer seeds suspended in the fluid remain in the camera`s focal plane for at least two consecutive images. However, the use of digital cameras for data acquisition is desirable to simplify and expedite the data analysis process. A technique was developed which will measure fluid velocities with PIV techniques using two successive digital images and two different framing rates simultaneously. The first part of the method will measure changes which occur to the flow field at the relatively slow framing rate of 53.8 ms. The second part will measure changes to the same flow field at the relatively fast framing rate of 100 to 320 {mu}s. The effectiveness of this technique was tested by studying the collapse of steam bubbles in a subcooled tank of water, a relatively high speed phenomena. The tracer particles were recorded and velocity vectors for the fluid were obtained far from the steam bubble collapse.

  9. High critical current density Bi2Sr2CaCu2O x /Ag wire containing oxide precursor synthesized from nano-oxides

    NASA Astrophysics Data System (ADS)

    Zhang, Yun; Johnson, Stephen; Naderi, Golsa; Chaubal, Manasi; Hunt, Andrew; Schwartz, Justin

    2016-09-01

    Bi2Sr2CaCu2O x (Bi2212)/Ag-alloy wires are manufactured via the oxide-powder-in-tube route by filling Ag/Ag-alloy tubes with Bi2212 oxide precursor, deforming into wire, restacking and heat treating using partial-melt processing (PMP). Recent studies propose several requirements on precursor properties, including stoichiometry, chemical homogeneity, carbon content and phase purity. Here, nanosize oxides produced by nGimat’s proprietary NanoSpray CombustionTM process are used as starting materials to synthesize Bi2212 oxide precursors via solid-state calcination. Oxide powders for wire fill (precursor powder) with precisely controlled stoichiometry and chemical homogeneity containing over 99 vol% of single Bi2212-phase are synthesized. Alkaline-earth cuprate are found to be the only impurity phase in the precursor powders. Phase transformation, carbon release and grain growth during calcination are studied through a series of quench studies. Effects of particle size, surface area, stoichiometry, chemical homogeneity and microstructures of the starting materials on Bi2212 formation and wire transport properties are discussed. Small particle size, high surface area and short diffusion length of the starting materials result in a rapid and homogeneous phase transformation to Bi2212, along with an early and rapid carbon release. The residual carbon in the precursor powder is between 50 and 90 ppm. The strong dependence of transport J c on precursor stoichiometry indicates that compositional variations within precursor powders should be less than 1.5 mol%. Two Bi-rich and Ca-deficient stoichiometries give higher wire transport critical current density, with the highest being 2520 A mm-2 (4.2 K, 5 T) after 1 bar PMP and 4560 A mm-2 (4.2 K, 5 T) after 100 bar overpressure (OP) processing. The low residual carbon content results in smaller and fewer voids within an OP-processed wire filament. Bi-rich and Ca-deficient stoichiometries and small compositional variations

  10. Hi-Fi SELEX: A High-Fidelity Digital-PCR Based Therapeutic Aptamer Discovery Platform.

    PubMed

    Ouellet, Eric; Foley, Jonathan H; Conway, Edward M; Haynes, Charles

    2015-08-01

    Current technologies for aptamer discovery typically leverage the systematic evolution of ligands by exponential enrichment (SELEX) concept by recursively panning semi-combinatorial ssDNA or RNA libraries against a molecular target. The expectation is that this iterative selection process will be sufficiently stringent to identify a candidate pool of specific high-affinity aptamers. However, failure of this process to yield promising aptamers is common, due in part to (i) limitations in library designs, (ii) retention of non-specific aptamers during screening rounds, (iii) excessive accumulation of amplification artifacts, and (iv) the use of screening criteria (binding affinity) that does not reflect therapeutic activity. We report a new selection platform, High-Fidelity (Hi-Fi) SELEX, that introduces fixed-region blocking elements to safeguard the functional diversity of the library. The chemistry of the target-display surface and the composition of the equilibration solvent are engineered to strongly inhibit non-specific retention of aptamers. Partition efficiencies approaching 10(6) are thereby realized. Retained members are amplified in Hi-Fi SELEX by digital PCR in a manner that ensures both elimination of amplification artifacts and stoichiometric conversion of amplicons into the single-stranded library required for the next selection round. Improvements to aptamer selections are first demonstrated using human α-thrombin as the target. Three clinical targets (human factors IXa, X, and D) are then subjected to Hi-Fi SELEX. For each, rapid enrichment of ssDNA aptamers offering an order-nM mean equilibrium dissociation constant (Kd) is achieved within three selection rounds, as quantified by a new label-free qPCR assay reported here. Therapeutic candidates against factor D are identified.

  11. A high-fidelity multiresolution digital elevation model for Earth systems

    NASA Astrophysics Data System (ADS)

    Duan, Xinqiao; Li, Lin; Zhu, Haihong; Ying, Shen

    2017-01-01

    The impact of topography on Earth systems variability is well recognised. As numerical simulations evolved to incorporate broader scales and finer processes, accurately assimilating or transforming the topography to produce more exact land-atmosphere-ocean interactions, has proven to be quite challenging. Numerical schemes of Earth systems often use empirical parameterisation at sub-grid scale with downscaling to express topographic endogenous processes, or rely on insecure point interpolation to induce topographic forcing, which creates bias and input uncertainties. Digital elevation model (DEM) generalisation provides more sophisticated systematic topographic transformation, but existing methods are often difficult to be incorporated because of unwarranted grid quality. Meanwhile, approaches over discrete sets often employ heuristic approximation, which are generally not best performed. Based on DEM generalisation, this article proposes a high-fidelity multiresolution DEM with guaranteed grid quality for Earth systems. The generalised DEM surface is initially approximated as a triangulated irregular network (TIN) via selected feature points and possible input features. The TIN surface is then optimised through an energy-minimised centroidal Voronoi tessellation (CVT). By devising a robust discrete curvature as density function and exact geometry clipping as energy reference, the developed curvature CVT (cCVT) converges, the generalised surface evolves to a further approximation to the original DEM surface, and the points with the dual triangles become spatially equalised with the curvature distribution, exhibiting a quasi-uniform high-quality and adaptive variable resolution. The cCVT model was then evaluated on real lidar-derived DEM datasets and compared to the classical heuristic model. The experimental results show that the cCVT multiresolution model outperforms classical heuristic DEM generalisations in terms of both surface approximation precision and

  12. Pure, single phase, high crystalline, chamfered-edge zeolite 4A synthesized from coal fly ash for use as a builder in detergents.

    PubMed

    Hui, K S; Chao, C Y H

    2006-09-01

    Single phase chamfered-edge zeolite 4A samples in pure form with a high crystallinity were synthesized by applying step-change of synthesis temperature during hydrothermal treatment of coal fly ash. The calcium binding capacity of these zeolite 4A samples (prepared from coal fly ash) and the commercial detergent grade zeolite 4A were tested for usage as a detergent builder. The results show that these zeolite 4A samples behaved similarly as the commercial one in removing calcium ions during the washing cycle. Moreover, from the leaching tests (evaluation of toxicological safety), the results show that these zeolite 4A samples leached the same elements (Sb, As, Se and Tl) as the commercial one with the concentrations in the same order of magnitude. This shows that the toxicological effect of the coal fly ash converted zeolite 4A was not worse than that of the commercial sample. Finally, economic and environmental aspects of converting coal fly ash to useful products were discussed.

  13. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    SciTech Connect

    Hans, M. Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M.; Primetzhofer, D.; Kurapov, D.; Arndt, M.; Rudigier, H.

    2014-09-07

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  14. High power density cell using nanostructured Sr-doped SmCoO3 and Sm-doped CeO2 composite powder synthesized by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Suzuki, Toshio; Sumi, Hirofumi; Hamamoto, Koichi; Fujishiro, Yoshinobu

    2016-01-01

    High power density solid oxide electrochemical cells were developed using nanostructure-controlled composite powder consisting of Sr-doped SmCoO3 (SSC) and Sm-doped CeO2 (SDC) for electrode material. The SSC-SDC nano-composite powder, which was synthesized by spray pyrolysis, had a narrow particle size distribution (D10, D50, and D90 of 0.59, 0.71, and 0.94 μm, respectively), and individual particles were spherical, composing of nano-size SSC and SDC fragments (approximately 10-15 nm). The application of the powder to a cathode for an anode-supported solid oxide fuel cell (SOFC) realized extremely fine cathode microstructure and excellent cell performance. The anode-supported SOFC with the SSC-SDC cathode achieved maximum power density of 3.65, 2.44, 1.43, and 0.76 W cm-2 at 800, 750, 700, and 650 °C, respectively, using humidified H2 as fuel and air as oxidant. This result could be explained by the extended electrochemically active region in the cathode induced by controlling the structure of the starting powder at the nano-order level.

  15. Rockfall susceptibility mapping of Yosemite Valley (USA) using a high-resolution digital elevation model

    NASA Astrophysics Data System (ADS)

    Pannatier, A.; Oppikofer, T.; Jaboyedoff, M.; Stock, G. M.

    2009-04-01

    In Yosemite National Park (California, USA) rockfalls from the steep valley flanks are frequent (>600 documented events in 150 years) and threaten infrastructure in this popular tourist area. This study focuses on a methodology to map the susceptibility to rockfall initiation based on a high-resolution digital elevation model (HRDEM) obtained from aerial laser scanning (1 meter cell size). This methodology is based on geometric factors derived from the HRDEM, i.e., the steepness of the topography, the presence of joints or fractures enabling either a planar or a wedge failure mechanism, and a high denudation potential. The slope angle histogram computed using standard GIS routines was simulated using Gaussian distributions, which were attributed to different parts of the topography, i.e., the cliffs, the valley flanks and the valley floor. Slopes steeper than 36° are found to form cliffs and thus potentially lead to rockfalls. A morpho-structural analysis of the HRDEM was performed in Coltop3D software to determine the major discontinuity sets that shape the topography. Kinematic analyses were made for each of these 7 discontinuity sets in order to determine the HRDEM cells that fulfil the geometric criteria for a planar or wedge failure mechanism. Most of the cliffs in Yosemite Valley enable one or both of these failure mechanisms. The denudation potential was assessed using the sloping local base level (SLBL) concept. The SLBL defines a basal erosion surface and the above lying rock masses (up to 400 m in some of the vertical cliffs) are susceptible to erosion by mass wasting. A thickness of 20 m above the SLBL surface was chosen as lower limit for the denudation potential criterion. The HRDEM cells that satisfy 1, 2 or all 3 criteria are considered having low, moderate and high susceptibility to rockfall initiation. The areas with highest susceptibility (El Capitan, Glacier Point, Yosemite Falls and Half Dome) coincide well with post-glacial talus accumulations

  16. A look-up-table digital predistortion technique for high-voltage power amplifiers in ultrasonic applications.

    PubMed

    Gao, Zheng; Gui, Ping

    2012-07-01

    In this paper, we present a digital predistortion technique to improve the linearity and power efficiency of a high-voltage class-AB power amplifier (PA) for ultrasound transmitters. The system is composed of a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and a field-programmable gate array (FPGA) in which the digital predistortion (DPD) algorithm is implemented. The DPD algorithm updates the error, which is the difference between the ideal signal and the attenuated distorted output signal, in the look-up table (LUT) memory during each cycle of a sinusoidal signal using the least-mean-square (LMS) algorithm. On the next signal cycle, the error data are used to equalize the signal with negative harmonic components to cancel the amplifier's nonlinear response. The algorithm also includes a linear interpolation method applied to the windowed sinusoidal signals for the B-mode and Doppler modes. The measurement test bench uses an arbitrary function generator as the DAC to generate the input signal, an oscilloscope as the ADC to capture the output waveform, and software to implement the DPD algorithm. The measurement results show that the proposed system is able to reduce the second-order harmonic distortion (HD2) by 20 dB and the third-order harmonic distortion (HD3) by 14.5 dB, while at the same time improving the power efficiency by 18%.

  17. Latency study of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

    NASA Astrophysics Data System (ADS)

    Meng, X. T.; Levin, D. S.; Chapman, J. W.; Li, D. C.; Yao, Z. E.; Zhou, B.

    2017-02-01

    The High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by the CERN Microelectronics group, has been proposed for the digitization of the thin-Resistive Plate Chambers (tRPC) in the ATLAS Muon Spectrometer Phase-1 upgrade project. These chambers, to be staged for higher luminosity LHC operation, will increase trigger acceptance and reduce or eliminate the fake muon trigger rates in the barrel-endcap transition region, corresponding to pseudo-rapidity range 1<|η|<1.3. Low level trigger candidates must be flagged within a maximum latency of 1075 ns, thus imposing stringent signal processing time performance requirements on the readout system in general, and on the digitization electronics in particular. This paper investigates the HPTDC signal latency performance based on a specially designed evaluation board coupled with an external FPGA evaluation board, when operated in triggerless mode, and under hit rate conditions expected in Phase-I. This hardware based study confirms previous simulations and demonstrates that the HPTDC in triggerless operation satisfies the digitization timing requirements in both leading edge and pair modes.

  18. Structure of a new form of silicon phosphate (SiP{sub 2}O{sub 7}) synthesized at high pressures and temperatures

    SciTech Connect

    Leinenweber, Kurt; Stearns, Linda A.; Nite, Jacob M.; Nemeth, Peter; Groy, Thomas L.

    2012-06-15

    A new high-pressure phase of SiP{sub 2}O{sub 7} has been found and its crystal structure solved and refined from a single crystal grown at a condition of 16 GPa and 2000 Degree-Sign C and recovered to ambient conditions. The material is monoclinic, with the space group P2{sub 1}/c and lattice parameters a=4.3042(7) A, b=7.1505(12) A, c=6.2897(11) A, {beta}=103.805(2). The structure contains SiO{sub 6} octahedra in a corner-sharing arrangement with P{sub 2}O{sub 7} dimers, the same structural elements and vertex-sharing present in all the low-pressure forms of SiP{sub 2}O{sub 7}. However, the network is more condensed: the topology of the packing of SiO{sub 6} octahedra and P{sub 2}O{sub 7} dimers (represented by Si and the bridging oxygen that both lie on centers of symmetry) is that of the CsCl structure, with some distortion. The resulting phase is 11.2% to 22.3% denser than the various low-pressure forms of SiP{sub 2}O{sub 7}. The structural data indicates that the P{sub 2}O{sub 7} dimers are linear (P-O-P angle=180 Degree-Sign ), an unusual feature for phosphates. - Graphical abstract: Single crystals of a new form of SiP{sub 2}O{sub 7} were synthesized at high pressure and temperature and the structure solved. Left: the high pressure multi-anvil assembly in a nest of 25.4 mm carbide anvil cubes. Center: the high pressure multi-anvil apparatus. Right: the monoclinic structure of the new phase: blue octahedra are SiO{sub 6} units and the yellow tetrahedra are PO{sub 4} units. Highlights: Black-Right-Pointing-Pointer Silicon phosphate transforms into a new phase at high pressure and temperature. Black-Right-Pointing-Pointer The high pressure phase is 14.8% denser than the low-pressure phase. Black-Right-Pointing-Pointer The structure is based on a linkage of SiO{sub 6} polyhedra and P{sub 2}O{sub 7} dimers. Black-Right-Pointing-Pointer The way the two units are packed is reminiscent of the CsCl arrangement. Black-Right-Pointing-Pointer The new structure is

  19. Efficient modeling of interconnects and capacitive discontinuities in high-speed digital circuits. Thesis

    NASA Technical Reports Server (NTRS)

    Oh, K. S.; Schutt-Aine, J.

    1995-01-01

    Modeling of interconnects and associated discontinuities with the recent advances high-speed digital circuits has gained a considerable interest over the last decade although the theoretical bases for analyzing these structures were well-established as early as the 1960s. Ongoing research at the present time is focused on devising methods which can be applied to more general geometries than the ones considered in earlier days and, at the same time, improving the computational efficiency and accuracy of these methods. In this thesis, numerically efficient methods to compute the transmission line parameters of a multiconductor system and the equivalent capacitances of various strip discontinuities are presented based on the quasi-static approximation. The presented techniques are applicable to conductors embedded in an arbitrary number of dielectric layers with two possible locations of ground planes at the top and bottom of the dielectric layers. The cross-sections of conductors can be arbitrary as long as they can be described with polygons. An integral equation approach in conjunction with the collocation method is used in the presented methods. A closed-form Green's function is derived based on weighted real images thus avoiding nested infinite summations in the exact Green's function; therefore, this closed-form Green's function is numerically more efficient than the exact Green's function. All elements associated with the moment matrix are computed using the closed-form formulas. Various numerical examples are considered to verify the presented methods, and a comparison of the computed results with other published results showed good agreement.

  20. Digitally controlled high-performance dc SQUID readout electronics for a 304-channel vector magnetometer

    NASA Astrophysics Data System (ADS)

    Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th

    2006-06-01

    Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.

  1. Scoria cones on Mars: Detailed investigation of morphometry based on high-resolution digital elevation models

    NASA Astrophysics Data System (ADS)

    Brož, Petr; Čadek, Ondřej; Hauber, Ernst; Rossi, Angelo Pio

    2015-09-01

    We analyze the shapes of 28 hypothesized scoria cones in three regions on Mars, i.e., Ulysses and Hydraotes Colles and Coprates Chasma. Using available High-Resolution Imaging Science Experiment and Context Camera (CTX) digital elevation models, we determine the basic morphometric characteristics of the cones and estimate from ballistic modeling the physical parameters of volcanic eruptions that could have formed them. When compared to terrestrial scoria cones, most of the studied cones show larger volumes (up to 4.2 × 109 m3), larger heights (up to 573 m), and smaller average slopes. The average slopes of the Ulysses, Hydraotes, and Coprates cones range between 7° and 25°, and the maximum slopes only rarely exceed 30°, which suggests only a minor role of scoria redistribution by avalanching. Ballistic analysis indicates that all cones were formed in a similar way, and their shapes are consistent with an ejection velocity about 2 times larger and a particle size about 20 times smaller than on Earth. Our results support the hypothesis that the investigated edifices were formed by low-energy Strombolian volcanic eruptions and hence are equivalent to terrestrial scoria cones. The cones in Hydraotes Colles and Coprates Chasma are on average smaller and steeper than the cones in Ulysses Colles, which is likely due to the difference in topographic elevation and the associated difference in atmospheric pressure. This study provides the expected morphometric characteristics of Martian scoria cones, which can be used to identify landforms consistent with this type of activity elsewhere on Mars and distinguish them from other conical edifices.

  2. A microwave synthesized CuxS and graphene oxide nanoribbon composite as a highly efficient counter electrode for quantum dot sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ghosh, Dibyendu; Halder, Ganga; Sahasrabudhe, Atharva; Bhattacharyya, Sayan

    2016-05-01

    To boost the photoconversion efficiency (PCE) of ever promising quantum dot sensitized solar cells (QDSSCs), and to improve the design of photoanodes, the ability of the counter electrode (CE) to effectively reduce the oxidized electrolyte needs special attention. A composite of a 15 wt% graphene oxide nanoribbon (GOR), obtained by unzipping multi-walled carbon nanotubes (MWCNTs), and CuxS intersecting hexagonal nanoplates, synthesized by a low cost, facile and scalable microwave synthesis route, is reported as a fascinating CE for QDSSCs. The best performing Cu1.18S-GOR CE could notably achieve a record PCE of ~3.55% for CdS sensitized QDSSCs, ~5.42% for in situ deposited CdS/CdSe co-sensitized QDSSCs and ~6.81% for CdTe/CdS/CdS dual sensitized QDSSCs, apart from increasing the PCE of previously reported QDSSCs. A systematic investigation of the CE design revealed the high electrocatalytic activity of GOR due to the presence of organic functional groups, graphitic edge sites and a quasi-one-dimensional (quasi-1D) structure, which increases the interfacial charge transfer kinetics from the CE to the polysulfide electrolyte. The highly stable Cu1.18S-GOR CE has the added advantage of a favourable energy band alignment with the redox potential of the polysulfide electrolyte, which reduces the loss of charge carriers and thus can increase the PCE of QDSSCs.To boost the photoconversion efficiency (PCE) of ever promising quantum dot sensitized solar cells (QDSSCs), and to improve the design of photoanodes, the ability of the counter electrode (CE) to effectively reduce the oxidized electrolyte needs special attention. A composite of a 15 wt% graphene oxide nanoribbon (GOR), obtained by unzipping multi-walled carbon nanotubes (MWCNTs), and CuxS intersecting hexagonal nanoplates, synthesized by a low cost, facile and scalable microwave synthesis route, is reported as a fascinating CE for QDSSCs. The best performing Cu1.18S-GOR CE could notably achieve a record PCE of ~3

  3. IEEE 1394/firewire a low cost, high speed, digital serial bus

    SciTech Connect

    Gaunt, R.

    1997-05-01

    Does the world need yet another 1/0 bus standard? If you need fast and cheap serial video communication, then the answer is yes. As technology advances, so too must data transport mechanisms advance. You can`t expect RS-232 to support real-time digital video, and if you can`t afford expensive professional serial video interfaces, (such as Sony`s Serial Digital Interface), Firewire may be a good solution. IEEE 1394, or commonly known as Firewire, is a general purpose serial bus that meets many of the 1/0 needs of today`s video and multimedia developers. For those of you who only read the first paragraph, here`s Firewire in a nutshell: It provides a guaranteed transfer rate of 10OMbps or 20OMbps of digital data (such as video direct from camera to computer), over an inexpensive, non-proprietary serial bus. Here is a list of its features.

  4. What can we Learn From High Resolution Digital Photography of Clouds?

    NASA Astrophysics Data System (ADS)

    Schwartz, S. E.; Vladutescu, D. V.; Aguirre, A.; Li, C.

    2014-12-01

    Commercially available digital cameras provide an unprecedented opportunity for detailed study of cloud structure. Key attributes of such cameras include large number of pixels, (e.g., 3456 x 4608) yielding rich detail of spatial structure, high spatial resolution (e.g., 30 μrad, corresponding to 30 mm for a cloud at 1 km height), and high dynamic range (16 bit in each of three color channels). These attributes permit detailed examination of spatial structure and temporal variability of the influence of clouds on the radiance field. Photography of clouds from the surface looking upwards affords the further advantage, relative to satellite imagery looking downward, that the background is black (space) with contributions to path radiance only from blue sky (Rayleigh scattering), aerosols, and clouds, without complication of surface-leaving radiance. Here we present preliminary results from measurements at Long Island, NY, in summer 2014. The camera was pointed vertically, typically with field of view 22 x 29 mrad (cf. solar diameter 9.3 mrad), corresponding to 22 x 29 m at 1 km. Even at this scale there is no uniquely determined cloud fraction. Cloud fraction defined as the fraction of pixels that encompass at least some cloud (DiGirolamo and Davies, JGR, 1997) is found to be highly dependent (several tens of percent) on threshold and on resolution, which can readily be artificially degraded by pixelating the image). Likewise, in contrast with findings of Sachs, Lovejoy, and Schertzer (Fractals, 2002) no unique fractal dimension appears to be associated with clouds, the retrieved value being dependent on approach and averaging method, Figure 1. Figure 1. Upper left, color image of zenith sky (2048 x 2048 pixels; 1 pixel = 6.3 µrad) at Upton, Long Island, NY (40.87˚ N; 72.89˚ W; 33 m MSL), July 3, 2014, 0803, local standard time). Lower left, two different cloud thresholdings, corresponding to cloud fraction 0.48 and 0.68. Right, squared magnitude of Fourier

  5. Evaluation of compressed digital high-definition video transmitted through the NASA communications system

    NASA Astrophysics Data System (ADS)

    Beakley, Guy W.; Kohn, Elliott S.

    1993-01-01

    A series of experiments was conducted over the past three years to prepare NASA for the use of high-definition television. In 1989 and in 1990, HDTV technology was evaluated for potential use in launch operations, real-time image analysis, and media dissemination at the Kennedy Space Center (KSC). Evaluation of camera and lens performance is reported here. In November 1991, an experiment was done at the Johnson Space Center (JSC) to evaluate the quality of HDTV that was digitized, compressed to a 45 Mbps data stream, and transmitted through the NASA communications network. The JSC experiment consisted of back-to-back bench tests of the Alcatel/Telettra high-definition coder/decoder (codec), followed by data transmission through the NASA Shuttle communications simulator, and most importantly, actual transmission through the NASA Tracking and Data Relay Satellite System (TDRSS), with a second satellite hop through a domestic satellite and a fiber-optic link at JSC. Static and dynamic test signals were used to test codec performance as were various types of subjective- test scenes with detail and motion. Included in the subjective material was IMAX film shot in space and transferred directly to high-definition video at 30 frames/second. Static tests highlighted the effects of the 54 MHz sampling rate in the codec. Color reproduction tests showed very little color error, even when transcoding externally from GBR signals. Dynamic test signals characterized the DCT and motion-compensation algorithm. Frame-by-frame analysis showed a small reduction in horizontal resolution, small color errors in fine detail, and reduced horizontal and vertical resolution immediately following transitions, where the effect was almost entirely masked by the transitions. Subjective codec performance on moving images at nominal TDRSS bit-error-rates (BER) was extremely good. The codec designers have done a very good job of leaving out information that is not perceived while including almost

  6. All-into-one strategy to synthesize mesoporous hybrid silicate microspheres from naturally rich red palygorskite clay as high-efficient adsorbents

    PubMed Central

    Wang, Wenbo; Tian, Guangyan; Wang, Dandan; Zhang, Zhifang; Kang, Yuru; Zong, Li; Wang, Aiqin

    2016-01-01

    A mesoporous hybrid silicate microsphere with superior adsorption performance has been successfully synthesized by employing an “all-into-one” strategy and a simple one-pot hydrothermal process using naturally abundant low-grade red palygorskite (PAL) clay as raw material in the presence of non-toxic SiO32− and Mg2+ ions. As is expected, both the PAL and associated minerals transformed into a new amorphous mesoporous hybrid silicate microsphere without using any additional pore-forming template. The mesoporous silicate microsphere shows a large pore size of 37.74 nm, high specific surface area of 489.81 m2/g (only 54.67 m2/g for raw PAL) and negative surface potential of −43.3 mV, and its maximum adsorption capabilities for Methylene bule (MB) and Crystal violet (CV) reach 407.95 mg/g and 397.22 mg/g, respectively. Meanwhile, 99.8% of MB (only 53% for raw PAL) and 99.7% of CV (only 43% for raw PAL) were sucessfully removed from 200 mg/L of initial dye solution by only using 1 g/L of the adsorbent. In addition, the spent adsorbent can be easily regenerated and repeatly reused for muptiple cycles. The study on adsorption mechanism revealed that electrostatic attraction, hydrogen bonding and chemical complexing interactions are the main factors contributed to the high dye adsorption. PMID:28000784

  7. DigitalLung: application of high-performance computing to biological system simulation.

    PubMed

    Burgreen, Greg W; Hester, Robert; Soni, Bela; Thompson, David; Walters, D Keith; Walters, Keisha

    2010-01-01

    The DigitalLung project represents an attempt to develop a multi-scale capability for simulating human respiration with application to predicting the effects of inhaled particulate matter. To accomplish this objective, DigitalLung integrates macroscale models of integrative human physiology, meso-to-microscale computational fluid dynamics simulations of a breathing human lung, meso-to-nanoscale particle transport and deposition models, and micro-to-nanoscale physical and chemical characterizations of particulate and their mass transfer through the mucosal layer to the epithelium. This chapter describes preliminary results and areas of ongoing research.

  8. Using high-resolution digital aerial imagery to map land cover

    USGS Publications Warehouse

    Dieck, J.J.; Robinson, Larry

    2014-01-01

    The Upper Midwest Environmental Sciences Center (UMESC) has used aerial photography to map land cover/land use on federally owned and managed lands for over 20 years. Until recently, that process used 23- by 23-centimeter (9- by 9-inch) analog aerial photos to classify vegetation along the Upper Mississippi River System, on National Wildlife Refuges, and in National Parks. With digital aerial cameras becoming more common and offering distinct advantages over analog film, UMESC transitioned to an entirely digital mapping process in 2009. Though not without challenges, this method has proven to be much more accurate and efficient when compared to the analog process.

  9. Measurements methodology for evaluation of Digital TV operation in VHF high-band

    NASA Astrophysics Data System (ADS)

    Pudwell Chaves de Almeida, M.; Vladimir Gonzalez Castellanos, P.; Alfredo Cal Braz, J.; Pereira David, R.; Saboia Lima de Souza, R.; Pereira da Soledade, A.; Rodrigues Nascimento Junior, J.; Ferreira Lima, F.

    2016-07-01

    This paper describes the experimental setup of field measurements carried out for evaluating the operation of the ISDB-TB (Integrated Services Digital Broadcasting, Terrestrial, Brazilian version) standard digital TV in the VHF-highband. Measurements were performed in urban and suburban areas in a medium-sized Brazilian city. Besides the direct measurements of received power and environmental noise, a measurement procedure involving the injection of Gaussian additive noise was employed to achieve the signal to noise ratio threshold at each measurement site. The analysis includes results of static reception measurements for evaluating the received field strength and the signal to noise ratio thresholds for correct signal decoding.

  10. Small pad RPCs as detector for high granularity digital hadron calorimetry

    NASA Astrophysics Data System (ADS)

    Ammosov, V.; Gapienko, V.; Ivanilov, A.; Sefkow, F.; Semak, A.; Sviridov, Yu.; Usenko, E.; Zaets, V.

    2004-11-01

    Requirements for sampling hadron calorimetry with gaseous active medium and digital read-out for a future linear e+e--collider (FLC) are formulated. Monogap glass Resistive Plate Chamber (RPC) prototypes equipped with 1cm2 read-out pads and operated in saturated avalanche and streamer modes are studied as a possible detector for digital hadron calorimetry. Operating characteristics of the prototypes such as induced charges, efficiencies and fired pad multiplicities are measured for different gas mixtures, gas gap widths and anode thicknesses, electronics thresholds, beam incident angle and intensity. Choice of RPC working performance is outlined.

  11. Digital One-Disc-One-Compound Method for High-Throughput Discovery of Prostate Cancer - Targeting Ligands

    DTIC Science & Technology

    2015-10-01

    1 AWARD NUMBER: W81XWH-13-1-0312 TITLE: Digital One-Disc-One-Compound Method for High-Throughput Discovery of Prostate Cancer-Targeting... Discovery of Prostate Cancer-Targeting Ligands 5b. GRANT NUMBERW81XWH-13-1-0312 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Drs. Tingrui Pan, Kit Lam...SUPPLEMENTARY NOTES 14. ABSTRACT Combinatorial library method significantly accelerates molecular discovery and identification in many areas of biology and

  12. High-speed digitization readout of silicon photomultipliers for time of flight positron emission tomography

    SciTech Connect

    Ronzhin, A.; Los, S.; Martens, M.; Ramberg, E.; Kim, H.; Chen, C.; Kao, C.; Niessen, K.; Zatserklyaniy, A.; Mazzillo, M.; Carbone, B.; /SGS Thomson, Catania

    2011-02-01

    We report on work to develop a system with about 100 picoseconds (ps) time resolution for time of flight positron emission tomography [TOF-PET]. The chosen photo detectors for the study were Silicon Photomultipliers (SiPM's). This study was based on extensive experience in studying timing properties of SiPM's. The readout of these devices used the commercial high speed digitizer DRS4. We applied different algorithms to get the best time resolution of 155 ps Guassian (sigma) for a LYSO crystal coupled to a SiPM. We consider the work as a first step in building a prototype TOF-PET module. The field of positron-emission-tomography (PET) has been rapidly developing. But there are significant limitations in how well current PET scanners can reconstruct images, related to how fast data can be acquired, how much volume they can image, and the spatial and temporal resolution of the generated photons. Typical modern scanners now include multiple rings of detectors, which can image a large volume of the patient. In this type of scanner, one can treat each ring as a separate detector and require coincidences only within the ring, or treat the entire region viewed by the scanner as a single 3 dimensional volume. This 3d technique has significantly better sensitivity since more photon pair trajectories are accepted. However, the scattering of photons within the volume of the patient, and the effect of random coincidences limits the technique. The advent of sub-nanosecond timing resolution detectors means that there is potentially much better rejection of scattered photon events and random coincidence events in the 3D technique. In addition, if the timing is good enough, then the origin of photons pairs can be determined better, resulting in improved spatial resolution - so called 'Time-of-Flight' PET, or TOF-PET. Currently a lot of activity has occurred in applications of SiPMs for TOF-PET. This is due to the devices very good time resolution, low profile, lack of high voltage

  13. Stable isotopes and Digital Elevation Models to study nutrient inputs in high-Arctic lakes

    NASA Astrophysics Data System (ADS)

    Calizza, Edoardo; Rossi, David; Costantini, Maria Letizia; Careddu, Giulio; Rossi, Loreto

    2016-04-01

    Ice cover, run-off from the watershed, aquatic and terrestrial primary productivity, guano deposition from birds are key factors controlling nutrient and organic matter inputs in high-Arctic lakes. All these factors are expected to be significantly affected by climate change. Quantifying these controls is a key baseline step to understand what combination of factors subtends the biological productivity in Arctic lakes and will drive their ecological response to environmental change. Basing on Digital Elevation Models, drainage maps, and C and N elemental content and stable isotope analysis in sediments, aquatic vegetation and a dominant macroinvertebrate species (Lepidurus arcticus Pallas 1973) belonging to Tvillingvatnet, Storvatnet and Kolhamna, three lakes located in North Spitsbergen (Svalbard), we propose an integrated approach for the analysis of (i) nutrient and organic matter inputs in lakes; (ii) the role of catchment hydro-geomorphology in determining inter-lake differences in the isotopic composition of sediments; (iii) effects of diverse nutrient inputs on the isotopic niche of Lepidurus arcticus. Given its high run-off and large catchment, organic deposits in Tvillingvatnet where dominated by terrestrial inputs, whereas inputs were mainly of aquatic origin in Storvatnet, a lowland lake with low potential run-off. In Kolhamna, organic deposits seem to be dominated by inputs from birds, which actually colonise the area. Isotopic signatures were similar between samples within each lake, representing precise tracers for studies on the effect of climate change on biogeochemical cycles in lakes. The isotopic niche of L. aricticus reflected differences in sediments between lakes, suggesting a bottom-up effect of hydro-geomorphology characterizing each lake on nutrients assimilated by this species. The presented approach proven to be an effective research pathway for the identification of factors subtending to nutrient and organic matter inputs and transfer

  14. The High-Tech and the Beautiful: Library Buildings, Digital Libraries, and the Future.

    ERIC Educational Resources Information Center

    Gilbert, Ellen D.

    2000-01-01

    Describes the new facilities at the New York Public Library, the British Library, and the National Library of France, including reference service, delivery time for books, and general ambience. Also reports on a conference that addressed issues related to scholarly communication and digital technology in the academic community. (LRW)

  15. Validating a high-resolution digital soil map for precision agriculture across multiple fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Digital soil mapping (DSM) for precision agriculture (PA) management is aimed at developing models that predict soil properties or classes using legacy soil data, sensors, and environmental covariates. The utility of DSM for PA is based on its ability to provide useful spatial soil information for o...

  16. Regional validation of a high-resolution digital soil map using soil profile attributes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Digital soil mapping (DSM) for precision agriculture (PA) management is aimed at developing models that predict soil properties or classes using legacy soil data, sensors, and environmental covariates. The utility of DSM for PA centers on its ability to provide soil information to optimize crop yiel...

  17. Digital karyotyping.

    PubMed

    Wang, Tian-Li; Maierhofer, Christine; Speicher, Michael R; Lengauer, Christoph; Vogelstein, Bert; Kinzler, Kenneth W; Velculescu, Victor E

    2002-12-10

    Alterations in the genetic content of a cell are the underlying cause of many human diseases, including cancers. We have developed a method, called digital karyotyping, that provides quantitative analysis of DNA copy number at high resolution. This approach involves the isolation and enumeration of short sequence tags from specific genomic loci. Analysis of human cancer cells by using this method identified gross chromosomal changes as well as amplifications and deletions, including regions not previously known to be altered. Foreign DNA sequences not present in the normal human genome could also be readily identified. Digital karyotyping provides a broadly applicable means for systematic detection of DNA copy number changes on a genomic scale.

  18. High-rate layered lithium-rich cathode nanomaterials for lithium-ion batteries synthesized with the assist of carbon spheres templates

    NASA Astrophysics Data System (ADS)

    Zhang, Linjing; Jiang, Jiuchun; Zhang, Caiping; Wu, Borong; Wu, Feng

    2016-11-01

    Nanoparticles of the layered lithium-rich cathode, Li[Li0.2Ni0.2Mn0.6]O2, have been synthesized via the two-step hydrothermal reactions combined with calcination process, while carbon spheres were used as templates. In the first hydrothermal step, the carbon spheres templates are obtained, and then the Li[Li0.2Ni0.2Mn0.6]O2 materials are prepared during the second hydrothermal step with addition of 0, 5, 10, 15 wt% as-prepared carbon spheres. Structural and morphological characterizations indicate the well-ordered layer-structured lithium-rich nanomaterials can be obtained with adding proper amount of carbon spheres templates. The electrochemical test demonstrates that the sample added 10 wt% carbon spheres (LNMO-Cs10) exhibits the best performance among all the samples. It delivers the optimal cycling ability, the least voltage decay, and the maximal discharge capacities of 238.7, 219.3, 204.8 and 182.7 mAh g-1 at 1C, 2C, 5C and 10C rates, respectively. EIS test shows that the LNMO-Cs10 material also has the reduced solid-electrolyte-interface resistance and charge transfer resistance. The excellent cycling ability and rate capability are possibly attributed to the better dispersibility of the nanoparticles with adding adequate amount of carbon spheres templates during materials synthesis. It can both guarantee the good contact between electrode and electrolytes and prevent high aggregation of nanoparticles.

  19. Crystal and magnetic structures and physical properties of a new pyroxene NaMnGe2O6 synthesized under high pressure.

    PubMed

    Cheng, Jinguang; Tian, Wei; Zhou, Jianshi; Lynch, Vincent M; Steinfink, Hugo; Manthiram, Arumugam; May, Andrew F; Garlea, Vasile O; Neuefeind, Joerg C; Yan, Jiaqiang

    2013-02-20

    A new pyroxene compound, NaMnGe(2)O(6), has been synthesized at 3 GPa and 800 °C and fully characterized by X-ray single-crystal diffraction, neutron powder diffraction, and measurements of magnetization and specific heat. NaMnGe(2)O(6) crystallizes into a monoclinic C2/c structure with unit-cell parameters a = 9.859(2) Å, b = 8.7507(18) Å, c = 5.5724(11) Å, and β = 105.64(3)° at 153 K. A cooperative Jahn-Teller distortion is formed by an ordering of the longest Mn-O bonds between two neighboring octahedra along the chain direction. This feature distinguishes NaMnGe(2)O(6) from other pyroxene compounds without Jahn-Teller active cations and suggests that the Jahn-Teller distortion competes with the intrinsic local distortion in the pyroxene structure. No orbital order-disorder transition has been found up to 750 K. Like other alkali-metal pyroxenes with S > (1)/(2), NaMnGe(2)O(6) (S = 2) was found to undergo a long-range antiferromagnetic (AF) ordering at T(N) = 7 K due to intrachain and interchain exchange interactions. Due to the peculiar structural features and the corresponding magnetic coupling, the weak AF spin ordering gives way to a ferromagnetic-like state at a sufficiently high magnetic field. Specific-heat measurements demonstrated that a large portion of the magnetic entropy, >60%, has been removed above T(N) as a result of strong spin correlations within the quasi-one-dimensional Mn(3+)-spin chains. The Reitveld refinement of neutron powder diffraction data gives a commensurate magnetic structure defined by k = [0 0 0.5] with Mn moments aligned mainly along the c-axis with a small component along both a- and b-axes.

  20. Co-synthesized Y-stabilized Bi2O3 and Sr-substituted LaMnO3 composite anode for high performance solid oxide electrolysis cell

    NASA Astrophysics Data System (ADS)

    Yan, Jingbo; Zhao, Zhe; Shang, Lei; Ou, Dingrong; Cheng, Mojie

    2016-07-01

    In this study we report a nano-composite anode comprised of Y-stabilized Bi2O3 (YSB) and Sr-substituted LaMnO3 (LSM) for solid oxide electrolysis cell (SOEC). The composite powder with primary particle size ranging from 20 to 80 nm is co-synthesized via a simple citric-nitrate combustion method. X-ray diffraction examination confirms cubic fluorite YSB and rhombohedral perovskite LSM as the main phases in the composite. Temperature programmed O2 desorption identifies remarkable low temperature desorption at 330 °C. Similarly, temperature programmed H2 reduction reveals strong reduction at 385 °C. The facile oxygen evolution on YSB-LSM may result from the increased amount of oxygen vacancies and improved oxygen ion mobility. A cell employing YSB-LSM composite anode achieves current density of -1.52 A cm-2 at 800 °C and 1.28 V, 50% higher than conventional LSM-YSZ cell. Impedance results and analysis of distribution of relaxation times indicate that the rate-determining anode processes are effectively accelerated on YSB-LSM. The activation energy for oxygen evolution reaction on YSB-LSM is reduced to 0.65 eV, notably lower than on LSM-YSZ (1.29 eV). The high performance of YSB-LSM composite anode is attributed to the fast ion decorporation on YSB, the facile O2 formation on LSM, and the abundant phase boundaries that facilitate the two processes.

  1. Effect of functionalized groups on gas-adsorption properties: syntheses of functionalized microporous metal-organic frameworks and their high gas-storage capacity.

    PubMed

    Wang, Yanlong; Tan, Chunhong; Sun, Zhihao; Xue, Zhenzhen; Zhu, Qilong; Shen, Chaojun; Wen, Yuehong; Hu, Shengmin; Wang, Yong; Sheng, Tianlu; Wu, Xintao

    2014-01-27

    The microporous metal-organic framework (MMOF) Zn4O(L1)2⋅9 DMF⋅9 H2O (1-H) and its functionalized derivatives Zn4O(L1-CH3)2⋅9 DMF⋅9 H2O (2-CH3) and Zn4O(L1-Cl)2⋅9 DMF⋅9 H2O (3-Cl) have been synthesized and characterized (H3L1=4-[N,N-bis(4-methylbenzoic acid)amino]benzoic acid, H3L1-CH3=4-[N,N-bis(4-methylbenzoic acid)amino]-2-methylbenzoic acid, H3L1-Cl=4-[N,N-bis(4-methylbenzoic acid)amino]-2-chlorobenzoic acid). Single-crystal X-ray diffraction analyses confirmed that the two functionalized MMOFs are isostructural to their parent MMOF, and are twofold interpenetrated three-dimensional (3D) microporous frameworks. All of the samples possess enduring porosity with Langmuir surface areas over 1950 cm(2) g(-1). Their pore volumes and surface areas decrease in the order 1-H>2-CH3 >3-Cl. Gas-adsorption studies show that the H2 uptakes of these samples are among the highest of the MMOFs (2.37 wt% for 3-Cl at 77 K and 1 bar), although their structures are interpenetrating. Furthermore, this work reveals that the adsorbate-adsorbent interaction plays a more important role in the gas-adsorption properties of these samples at low pressure, whereas the effects of the pore volumes and surface areas dominate the gas-adsorption properties at high pressure.

  2. Width-controlled M-type hexagonal strontium ferrite (SrFe12O19) nanoribbons with high saturation magnetization and superior coercivity synthesized by electrospinning

    PubMed Central

    Jing, Panpan; Du, Jinlu; Wang, Jianbo; wei, Jinwu; Pan, Lining; Li, Jianan; Liu, Qingfang

    2015-01-01

    Width-controlled M-type hexagonal SrFe12O19 nanoribbons were synthesized for the first time via polyvinylpyrrolidone (PVP) sol assisted electrospinning followed by heat treatment in air, and their chemical composition, microstructure and magnetic performance were investigated. Results demonstrated that as-obtained SrFe12O19 nanoribbons were well-crystallized with high purity. Each nanoribbon was self-assembled by abundant single-domain SrFe12O19 nanoparticles and was consecutive on structure and uniform on width. PVP in the spinning solution played a significant influence on the microstructure features of SrFe12O19 nanoribbons. With PVP concentration increasing, the ribbon-width was increased but the particle-size was reduced, which distributed on a same ribbon were more intensive, and then the ribbon-surface became flat. The room temperature magnetic performance investigation revealed that considerable large saturation magnetization (Ms) and coercivity (Hc) were obtained for all SrFe12O19 nanoribbons, and they increased with the ribbon-width broadening. The highest Ms of 67.9 emu·g−1 and Hc of 7.31 kOe were concurrently acquired for SrFe12O19 nanoribbons with the maximum ribbon-width. Finally, the Stoner-Wohlfarth curling model was suggested to dominate the magnetization reverse of SrFe12O19 nanoribbons. It is deeply expected that this work is capable of opening up a new insights into the architectural design of 1D magnetic materials and their further utilization. PMID:26462750

  3. Method and apparatus for digitally based high speed x-ray spectrometer for direct coupled use with continuous discharge preamplifiers

    DOEpatents

    Warburton, William K.

    1998-01-01

    A high speed, digitally based, signal processing system which accepts directly coupled input data from a detector with a continuous discharge type preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system's principal elements are an analog signal conditioning section, a combinatorial logic section which implements digital triangular filtering and pileup inspection, and a microprocessor which accepts values captured by the logic section and uses them to compute x-ray energy values. Operating without pole-zero correction, the system achieves high resolution by capturing, in conjunction with each peak value from the digital filter, an associated value of the unfiltered signal, and using this latter signal to correct the former for errors which arise from its local slope terms. This correction greatly reduces both energy resolution degradation and peak centroid shifting in the output spectrum as a function of input count rate. When the noise of this correction is excessive, a modification allows two filtered averages of the signal to be captured and a corrected peak amplitude computed therefrom.

  4. Method and apparatus for digitally based high speed x-ray spectrometer for direct coupled use with continuous discharge preamplifiers

    DOEpatents

    Warburton, W.K.

    1998-06-30

    A high speed, digitally based, signal processing system is disclosed which accepts directly coupled input data from a detector with a continuous discharge type preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system`s principal elements are an analog signal conditioning section, a combinatorial logic section which implements digital triangular filtering and pileup inspection, and a microprocessor which accepts values captured by the logic section and uses them to compute x-ray energy values. Operating without pole-zero correction, the system achieves high resolution by capturing, in conjunction with each peak value from the digital filter, an associated value of the unfiltered signal, and using this latter signal to correct the former for errors which arise from its local slope terms. This correction greatly reduces both energy resolution degradation and peak centroid shifting in the output spectrum as a function of input count rate. When the noise of this correction is excessive, a modification allows two filtered averages of the signal to be captured and a corrected peak amplitude computed therefrom. 14 figs.

  5. High-quality virus images obtained by transmission electron microscopy and charge coupled device digital camera technology.

    PubMed

    Tiekotter, Kenneth L; Ackermann, Hans-W

    2009-07-01

    The introduction of digital cameras has led to the publication of numerous virus electron micrographs of low magnification, poor contrast, and low resolution. Described herein is the methodology for obtaining highly contrasted virus images in the magnification range of approximately 250,000-300,000x. Based on recent advances in charged couple device (CCD) digital camera technology, methodology is described for optimal imaging parameters for using CCD cameras mounted in side- and bottom-mount position of electron microscopes and the recommendation of higher accelerating voltages, larger objective apertures, and small spot size. The authors are concerned with the principles of image formation and modulation, advocate a better use of imaging software to improve image quality, and recommend either pre- or post-acquisition adjustment for distributing pixel intensities of compressed histograms over the entire range of tonal values.

  6. A high precision method for mapping phase to amplitude in direct digital synthesis and its hardware implementation.

    PubMed

    Cao, Zhang; Song, Wei; Peng, Zhicong; Xu, Lijun

    2014-11-01

    There exist a number of algorithms to map the phase to amplitude in direct digital synthesis (DDS). For DDS with more than 14 output bits, the Coordinate Rotation Digital Computer (CORDIC) algorithm is well known for its high precision. Also, it is effective in solutions where there is the need of in-phase and quadrature components simultaneously because the algorithm calculates both. In this paper, a Taylor expansion based method was proposed to calculate both in-phase and quadrature at the same time. Numerical simulations for different data format, e.g., double and finite bits, were carried out in Matlab and Quartus, which were followed by the hardware implementation in Field Programmable Gate Array. The results demonstrated that the proposed method possessed higher precision and exhausted less logic elements than the CORDIC algorithm.

  7. Analysis and design of a high power, digitally-controlled spacecraft power system

    NASA Technical Reports Server (NTRS)

    Lee, F. C.; Cho, B. H.

    1990-01-01

    The progress to date on the analysis and design of a high power, digitally controlled spacecraft power system is described. Several battery discharger topologies were compared for use in the space platform application. Updated information has been provided on the battery voltage specification. Initially it was thought to be in the 30 to 40 V range. It is now specified to be 53 V to 84 V. This eliminated the tapped-boost and the current-fed auto-transformer converters from consideration. After consultations with NASA, it was decided to trade-off the following topologies: (1) boost converter; (2) multi-module, multi-phase boost converter; and (3) voltage-fed push-pull with auto-transformer. A non-linear design optimization software tool was employed to facilitate an objective comparison. Non-linear design optimization insures that the best design of each topology is compared. The results indicate that a four-module, boost converter with each module operating 90 degrees out of phase is the optimum converter for the space platform. Large-signal and small-signal models were generated for the shunt, charger, discharger, battery, and the mode controller. The models were first tested individually according to the space platform power system specifications supplied by NASA. The effect of battery voltage imbalance on parallel dischargers was investigated with respect to dc and small-signal responses. Similarly, the effects of paralleling dischargers and chargers were also investigated. A solar array and shunt model was included in these simulations. A model for the bus mode controller (power control unit) was also developed to interface the Orbital replacement Unit (ORU) model to the platform power system. Small signal models were used to generate the bus impedance plots in the various operating modes. The large signal models were integrated into a system model, and time domain simulations were performed to verify bus regulation during mode transitions. Some changes have

  8. High Resolution Photogrammetric Digital Elevation Models Across Calving Fronts and Meltwater Channels in Greenland

    NASA Astrophysics Data System (ADS)

    Le Bel, D. A.; Brown, S.; Zappa, C. J.; Bell, R. E.; Frearson, N.; Tinto, K. J.

    2014-12-01

    Photogrammetric digital elevation models (DEMs) are a powerful approach for understanding elevation change and dynamics along the margins of the large ice sheets. The IcePod system, mounted on a New York Air National Guard LC-130, can measure high-resolution surface elevations with a Riegl VQ580 scanning laser altimeter and Imperx Bobcat IGV-B6620 color visible-wavelength camera (6600x4400 resolution); the surface temperature with a Sofradir IRE-640L infrared camera (spectral response 7.7-9.5 μm, 640x512 resolution); and the structure of snow and ice with two radar systems. We show the use of IcePod imagery to develop DEMs across calving fronts and meltwater channels in Greenland. Multiple over-flights of the Kangerlussaq Airport ramp have provided a test of the technique at a location with accurate, independently-determined elevation. Here the photogrammetric DEM of the airport, constrained by ground control measurements, is compared with the Lidar results. In July 2014 the IcePod ice-ocean imaging system surveyed the calving fronts of five outlet glaciers north of Jakobshavn Isbrae. We used Agisoft PhotoScan to develop a DEM of each calving front using imagery captured by the IcePod systems. Adjacent to the ice sheet, meltwater plumes foster mixing in the fjord, moving warm ocean water into contact with the front of the ice sheet where it can undercut the ice front and trigger calving. The five glaciers provide an opportunity to examine the calving front structure in relation to ocean temperature, fjord circulation, and spatial scale of the meltwater plumes. The combination of the accurate DEM of the calving front and the thermal imagery used to constrain the temperature and dynamics of the adjacent plume provides new insights into the ice-ocean interactions. Ice sheet margins provide insights into the connections between the surface meltwater and the fate of the water at the ice sheet base. Surface meltwater channels are visualized here for the first time using

  9. PULSE SYNTHESIZING GENERATOR

    DOEpatents

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  10. Enzyme-synthesized highly branched maltodextrins have slow glucose generation at the mucosal α-glucosidase level and are slowly digestible in vivo.

    PubMed

    Lee, Byung-Hoo; Yan, Like; Phillips, Robert J; Reuhs, Bradley L; Jones, Kyra; Rose, David R; Nichols, Buford L; Quezada-Calvillo, Roberto; Yoo, Sang-Ho; Hamaker, Bruce R

    2013-01-01

    For digestion of starch in humans, α-amylase first hydrolyzes starch molecules to produce α-limit dextrins, followed by complete hydrolysis to glucose by the mucosal α-glucosidases in the small intestine. It is known that α-1,6 linkages in starch are hydrolyzed at a lower rate than are α-1,4 linkages. Here, to create designed slowly digestible carbohydrates, the structure of waxy corn starch (WCS) was modified using a known branching enzyme alone (BE) and an in combination with β-amylase (BA) to increase further the α-1,6 branching ratio. The digestibility of the enzymatically synthesized products was investigated using α-amylase and four recombinant mammalian mucosal α-glucosidases. Enzyme-modified products (BE-WCS and BEBA-WCS) had increased percentage of α-1,6 linkages (WCS: 5.3%, BE-WCS: 7.1%, and BEBA-WCS: 12.9%), decreased weight-average molecular weight (WCS: 1.73×10(8) Da, BE-WCS: 2.76×10(5) Da, and BEBA-WCS 1.62×10(5) Da), and changes in linear chain distributions (WCS: 21.6, BE-WCS: 16.9, BEBA-WCS: 12.2 DPw). Hydrolysis by human pancreatic α-amylase resulted in an increase in the amount of branched α-limit dextrin from 26.8% (WCS) to 56.8% (BEBA-WCS). The α-amylolyzed samples were hydrolyzed by the individual α-glucosidases (100 U) and glucogenesis decreased with all as the branching ratio increased. This is the first report showing that hydrolysis rate of the mammalian mucosal α-glucosidases is limited by the amount of branched α-limit dextrin. When enzyme-treated materials were gavaged to rats, the level of postprandial blood glucose at 60 min from BEBA-WCS was significantly higher than for WCS or BE-WCS. Thus, highly branched glucan structures modified by BE and BA had a comparably slow digesting property both in vitro and in vivo. Such highly branched α-glucans show promise as a food ingredient to control postprandial glucose levels and to attain extended glucose release.

  11. Crystal and magnetic structures and physical properties of a new pyroxene NaMnGe2O6 synthesized under high pressure

    SciTech Connect

    Yan, Jiaqiang; Tian, Wei; May, Andrew F; Cheng, J G; Zhou, J.-S.; Garlea, Vasile O; Neuefeind, Joerg C; Steinfink, Hugo; Lynch, V

    2013-01-01

    A new pyroxene NaMnGe2O6 has been synthesized at 3 GPa and 800 C, and fully characterized by x-ray single-crystal diffraction and neutron powder diffraction, measurements of magnetization and specific heat. Like other majority sodium pyroxenes, NaMnGe2O6 crystallizes into a monoclinic C2/c structure with unit-cell parameters a = 9.859(2) , b = 8.7507(18) , c = 5.5724(11) , and =105.64(3) at room temperature. The crystal structure is featured by quasi-one-dimensional chains of skew edge-sharing MnO6 octahedra running along the crystallographic c axis; these chains are connected by non-magnetic GeO4 tetrahedra, so as to lead to a low-dimensional magnetism. The highly distorted MnO6 octahedron consisting of three Mn-O bond lengths, i.e. 1.918 , 1.991 , and 2.198 , is consistent with the Jahn-Teller effect at Mn3+ in a cubic crystal field. A long-range cooperative Jahn-Teller distortion is formed by ordering longest Mn-O bonds between two neighboring octahedra along the chain direction. No orbital order-disorder transition has been found up to 750 K as checked by magnetic susceptibility. Like other alkali-metal pyroxenes with S > , NaMnGe2O6 (S = 2) was found to undergo a long-range antiferromagnetic ordering at TN = 7 K at low magnetic field due to the exchange interactions along and between chains. Due to the peculiar structural features and the corresponding magnetic coupling, the weak AF spin ordering gives way to a ferromagnetic-like state at a sufficiently high magnetic field. Specific-heat measurements demonstrated that a large portion of the magnetic entropy, i.e. > 60 %, has been removed above TN as a result of strong spin correlations within the quasi-one-dimensional Mn3+-spin chains. Neutron powder diffraction study suggests a commensurate magnetic structure defined by k = [0 0 0.5] with Mn moments aligned along the c axis. The present study on NaMnGe2O6 completed the evolution of magnetic properties as a function of the d-orbital occupancy from d1 to d5 in

  12. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

    A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

  13. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

    1984-01-01

    A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

  14. Comparison of the image quality of a high-resolution screen-film system and a digital flat panel detector system in avian radiography.

    PubMed

    Bochmann, Monika; Ludewig, Eberhard; Krautwald-Junghanns, Maria-Elisabeth; Pees, Michael

    2011-01-01

    A conventional high-resolution screen-film system was compared with a digital detector system. A total of 20 birds (14 pigeons and six psittacine birds) with an average body mass of 533g were examined in dorsoventral as well as lateral projections. Digital radiographs were acquired with the same mAs as well as half the mAs used for the conventional radiographs. Three criteria and one overall assessment were defined for each of four anatomic regions and assessed by five veterinarians using a score system. Comparison of the ratings was done by visual grading analysis. For the majority of criteria, there was no significant difference regarding image quality between the digital and screen-film projections. However, for certain criteria the quality of the digital images was significantly superior. Using the same mAs as for the conventional radiographs, the humeral joint surfaces and the honeycomb structure of the lung were assessed as superior with the digital imaging system. The tracheal rings and the delineation of the trachea from the surrounding tissue were also superior with the digital system. Assessment of the trabecular structure of the humerus was superior when the full mAs was used compared with the reduced mAs. In conclusion the digital technique is equal or superior to the conventional screen-film high-resolution system for pet birds of a medium size. With some limitations, a dose reduction is possible with the digital system.

  15. Clustering of High Redshift (z>2.9) Quasars from the Sloan Digital Sky Survey

    SciTech Connect

    Shen, Yue; Strauss, Michael A.; Oguri, Masamune; Hennawi, Joseph F.; Fan, Xiaohui; Richards, Gordon T.; Hall, Patrick B.; Schneider, Donald P.; Szalay, Alexander S.; Thakar, Anirudda R.; Berk, Daniel E.Vanden; Anderson, Scott F.; Bahcall, Neta A.; /KIPAC, Menlo Park

    2006-11-30

    We study the two-point correlation function of a uniformly selected sample of 4,428 optically selected luminous quasars with redshift 2.9 {le} z {le} 5.4 selected over 4041 deg{sup 2} from the Fifth Data Release of the Sloan Digital Sky Survey. We fit a power-law to the projected correlation function w{sub p}(r{sub p}) to marginalize over redshift space distortions and redshift errors. For a real-space correlation function of the form {zeta}(r) = (r/r{sub 0}){sup -{gamma}}, the fitted parameters in comoving coordinates are r{sub 0} = 15.2 {+-} 2.7 h{sup -1} Mpc and {gamma} = 2.0 {+-} 0.3, over a scale range 4 {le} r{sub p} {le} 150 h{sup -1} Mpc. Thus high-redshift quasars are appreciably more strongly clustered than their z {approx} 1.5 counterparts, which have a comoving clustering length r{sub 0} {approx} 6.5 h{sup -1} Mpc. Dividing our sample into two redshift bins: 2.9 {le} z {le} 3.5 and z {ge} 3.5, and assuming a power-law index {gamma} = 2.0, we find a correlation length of r{sub 0} = 16.9 {+-} 1.7 h{sup -1} Mpc for the former, and r{sub 0} = 24.3 {+-} 2.4 h{sup -1} Mpc for the latter. Strong clustering at high redshift indicates that quasars are found in very massive, and therefore highly biased, halos. Following Martini & Weinberg, we relate the clustering strength and quasar number density to the quasar lifetimes and duty cycle. Using the Sheth & Tormen halo mass function, the quasar lifetime is estimated to lie in the range 4 {approx} 50 Myr for quasars with 2.9 {le} z {le} 3.5; and 30 {approx} 600 Myr for quasars with z {ge} 3.5. The corresponding duty cycles are 0.004 {approx} 0.05 for the lower redshift bin and 0.03 {approx} 0.6 for the higher redshift bin. The minimum mass of halos in which these quasars reside is 2-3 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with 2.9 {le} z {le} 3.5 and 4-6 x 10{sup 12} h{sup -1} M{sub {circle_dot}} for quasars with z {ge} 3.5; the effective bias factor b{sub eff} increases with redshift, e.g., b

  16. A New Flat-Panel Digital Mammography Detector with Avalanche Photoconductor and High-Resolution Field Emitter Readout

    DTIC Science & Technology

    2005-06-01

    electric field Ese as opposed to the fixed high conversion gain of HgI 2 or PbI2. One of 4 the practical problems of having a fixed high gain is that the...Nylen, K. Shah, L. Melekhov and H. Hermon, "Comparison of PbI2 and HgI 2 for direct detection active matrix x-ray image sensors", J. Appl. Phys. 91...a-Se and HgI 2", Appl. Phys. Lett. 80, 1664-1666 (2002) 23 14 N. Matsuura, Wei Zhao, Z. Huang and J. A. Rowlands, "Digital radiology using active

  17. Synthesis and Characteristics of Protective Coating on Thin Cover Layer for High Density-Digital Versatile Disc

    NASA Astrophysics Data System (ADS)

    Chang, Dohoon; Yoon, Duseop; Ro, Myongdo; Hwang, Inoh; Park, Insik; Shin, Dongho

    2003-02-01

    This study relates to the optical disc used in the high-density digital versatile disc (HD-DVD) system that uses a high numerical aperture of 0.85 at 405 nm wavelength. The disc has a protective layer formed on the light-incident surface for protection against damage and dust. The synthesis of the UV-curable resinous material, as means of making a protective layer within sufficient margins of thickness variation and optical and mechanical properties, was investigated. In addition, the dynamic characteristics, including reflectivity, fluctuation of the RF signal and noise level, were also investigated.

  18. Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy

    NASA Astrophysics Data System (ADS)

    Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J.

    2014-03-01

    Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content.

  19. Characterizing the Performance of a High-Speed ADC for the Sma Digital Backend

    NASA Astrophysics Data System (ADS)

    Patel, N. A.; Wilson, R. W.; Primiani, R.; Weintroub, J.; Test, J.; Young, K.

    We report on tests of a 5 Gs/s analog-to-digital converter (ADC) used in the new Submillimeter Array (SMA) Digital Backend (DBE). The ADC is e2v EV8AQ160, with 8-bit resolution and 4 interleaved cores, operated in single-channel mode. We measured the frequency response, Signal to Noise and Distortion (SINAD), Spurious Free Dynamic Range (SFDR), Noise Power Ratio and intermodulation distortion over the bandwidth of 2.25 GHz. The performance of this ADC is found to be adequate for our application in the SMA DBE. We describe the procedure of aligning the four cores for adjustments of offset, gain and phase parameters which improve the performance of the ADC, particularly in SINAD and SFDR.

  20. Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy

    SciTech Connect

    Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J.

    2014-03-15

    Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content.

  1. High Cadence Digital Full Disk Hα Patrol Device at Kanzelhöhe

    NASA Astrophysics Data System (ADS)

    Otruba, W.

    1999-09-01

    The need for monitoring the sun in the prominent Hα-line is evident. For a long time this recording was done on photographic film at Kanzelhöhe Solar Observatory. Now with the evolution of CCDs and digital mass storage devices it is possible and even more economical to do this job digitally. A 1kx1k CCD camera and a standard frame grabbing system on a conventional PC are attached to the established Kanzelhöhe Patrol Instrument with a narrow band Hα filter. At the present state a very simple frame selection mechanism is installed to improve the image quality. The data are archived on CDs. The development of a standard image processing and evaluation system is in progress. Low cadence synoptic images are currently fed into the SOHO synoptic database. Instant data access from the Kanzelhöhe database via WWW is planned.

  2. Television for the 21st century: initial experience with digital high-definition television broadcast

    NASA Astrophysics Data System (ADS)

    Mahrer, Stephen M.

    2000-08-01

    The advent of US Digital Television Broadcasting in the late fall of 1998 has profoundly changed both the technology and business of 'Television' as we have grown to known it. US DTV, encompassing as it does a wide variety of 'voluntary' signal formats, presents today's broadcaster with an unparalleled choice of the 'right tool for the job.' This paper will explore the technical aspects of some of those choices and the potential for DTV equipment application to non-broadcast environments.

  3. Microvalve Enabled Digital Microfluidic Systems for High Performance Biochemical and Genetic Analysis.

    PubMed

    Jensen, Erik C; Zeng, Yong; Kim, Jungkyu; Mathies, Richard A

    2010-12-01

    Microfluidic devices offer unparalleled capability for digital microfluidic automation of sample processing and complex assay protocols in medical diagnostic and research applications. In our own work, monolithic membrane valves have enabled the creation of two platforms that precisely manipulate discrete, nanoliter-scale volumes of sample. The digital microfluidic Automaton uses two-dimensional microvalve arrays to combinatorially process nanoliter-scale sample volumes. This programmable system enables rapid integration of diverse assay protocols using a universal processing architecture. Microfabricated emulsion generator array (MEGA) devices integrate actively controlled 3-microvalve pumps to enable on-demand generation of uniform droplets for statistical encapsulation of microbeads and cells. A MEGA device containing 96 channels confers the capability of generating up to 3.4 × 10(6) nanoliter-volume droplets per hour for ultrahigh-throughput detection of rare mutations in a vast background of normal genotypes. These novel digital microfluidic platforms offer significant enhancements in throughput, sensitivity, and programmability for automated sample processing and analysis.

  4. Novel digital logic gate for high-performance CMOS imaging system

    NASA Astrophysics Data System (ADS)

    Chung, Hoon H.; Joo, Youngjoong

    2004-06-01

    In these days, the CMOS image sensors are commonly used in many low resolution applications because the CMOS imaging system has several advantages against the conventional CCD imaging system. However, there are still several problems for the realization of the single-chip CMOS imaging system. One main problem is the substrate coupling noise, which is caused by the digital switching noise. Because the CMOS image sensors share the same substrate with surrounding digital circuit, it is difficult for the CMOS image sensor to get a good performance. In order to investigate the substrate coupling noise effect of the CMOS image sensor, the conventional CMOS logic, C-CBL (Complementary-Current balanced logic) and proposed low switching noise logic are simulated and compared. Consequently, the proposed logic compensates not only the large digital switching noise of conventional CMOS logic ,but also the huge power consumption of the C-CBL. Both the total instantaneous current behaviors on the power supply and the peak-to-peak voltages of the substrate voltage variation (di/dt noise) are investigated. The simulation is performed by AMI 0.5μm CMOS technology.

  5. Morphology in the Digital Age: Integrating High Resolution Description of Structural Alterations with Phenotypes and Genotypes

    PubMed Central

    Nast, Cynthia C.; Lemley, Kevin V.; Hodgin, Jeffrey B.; Bagnasco, Serena; Avila-Casado, Carmen; Hewitt, Stephen M; Barisoni, Laura

    2015-01-01

    Conventional light microscopy (CLM) has been used to characterize and classify renal diseases, evaluate histopathology in studies and trials, and educate renal pathologists and nephrologists. The advent of digital pathology, in which a glass slide can be scanned to create whole slide images (WSI) for viewing and manipulating on a computer monitor, provides real and potential advantages over CLM. Software tools such as annotation, morphometry and image analysis can be applied to WSIs for studies or educational purposes, and the digital images are globally available to clinicians, pathologists and investigators. New ways of assessing renal pathology with observational data collection may allow better morphologic correlations and integration with molecular and genetic signatures, refinements of classification schema, and understanding of disease pathogenesis. In multicenter studies, WSI, which require additional quality assurance steps, provide efficiencies by reducing slide shipping and consensus conference costs, and allowing anytime anywhere slide viewing. While validation studies for the routine diagnostic use of digital pathology still are needed, this is a powerful tool currently available for translational research, clinical trials and education in renal pathology. PMID:26215864

  6. Real-time digital heterodyne interferometer for high resolution plasma density measurements at ISTTOK

    SciTech Connect

    Marques, T. G.; Gouveia, A.; Pereira, T.; Fortunato, J.; Carvalho, B. B.; Sousa, J.; Silva, C.; Fernandes, H.

    2008-10-15

    With the implementation of alternating discharges (ac) at the ISTTOK tokamak, the typical duration of the discharges increased from 35 to 250 ms. This time increase created the need for a real-time electron density measurement in order to control the plasma fueling. The diagnostic chosen for the real-time calculation was the microwave interferometer. The ISTTOK microwave interferometer is a heterodyne system with quadrature detection and a probing frequency of 100 GHz ({lambda}{sub 0}=3 mm). In this paper, a low-cost approach for real-time diagnostic using a digital signal programable intelligent computer embedded system is presented, which allows the measurement of the phase with a 1% fringe accuracy in less than 6 {mu}s. The system increases its accuracy by digitally correcting the offsets of the input signals and making use of a judicious lookup table optimized to improve the nonlinear behavior of the transfer curve. The electron density is determined at a rate of 82 kHz (limited by the analog to digital converter), and the data are transmitted for each millisecond although this last parameter could be much lower (around 12 {mu}s--each value calculated is transmitted). In the future, this same system is expected to control plasma actuators, such as the piezoelectric valve of the hydrogen injection system responsible for the plasma fueling.

  7. Real-time digital heterodyne interferometer for high resolution plasma density measurements at ISTTOK.

    PubMed

    Marques, T G; Gouveia, A; Pereira, T; Fortunato, J; Carvalho, B B; Sousa, J; Silva, C; Fernandes, H

    2008-10-01

    With the implementation of alternating discharges (ac) at the ISTTOK tokamak, the typical duration of the discharges increased from 35 to 250 ms. This time increase created the need for a real-time electron density measurement in order to control the plasma fueling. The diagnostic chosen for the real-time calculation was the microwave interferometer. The ISTTOK microwave interferometer is a heterodyne system with quadrature detection and a probing frequency of 100 GHz (lambda(0)=3 mm). In this paper, a low-cost approach for real-time diagnostic using a digital signal programmable intelligent computer embedded system is presented, which allows the measurement of the phase with a 1% fringe accuracy in less than 6 micros. The system increases its accuracy by digitally correcting the offsets of the input signals and making use of a judicious lookup table optimized to improve the nonlinear behavior of the transfer curve. The electron density is determined at a rate of 82 kHz (limited by the analog to digital converter), and the data are transmitted for each millisecond although this last parameter could be much lower (around 12 micros--each value calculated is transmitted). In the future, this same system is expected to control plasma actuators, such as the piezoelectric valve of the hydrogen injection system responsible for the plasma fueling.

  8. High-accuracy 3-D modeling of cultural heritage: the digitizing of Donatello's "Maddalena".

    PubMed

    Guidi, Gabriele; Beraldin, J Angelo; Atzeni, Carlo

    2004-03-01

    Three-dimensional digital modeling of Heritage works of art through optical scanners, has been demonstrated in recent years with results of exceptional interest. However, the routine application of three-dimensional (3-D) modeling to Heritage conservation still requires the systematic investigation of a number of technical problems. In this paper, the acquisition process of the 3-D digital model of the Maddalena by Donatello, a wooden statue representing one of the major masterpieces of the Italian Renaissance which was swept away by the Florence flood of 1966 and successively restored, is described. The paper reports all the steps of the acquisition procedure, from the project planning to the solution of the various problems due to range camera calibration and to material non optically cooperative. Since the scientific focus is centered on the 3-D model overall dimensional accuracy, a methodology for its quality control is described. Such control has demonstrated how, in some situations, the ICP-based alignment can lead to incorrect results. To circumvent this difficulty we propose an alignment technique based on the fusion of ICP with close-range digital photogrammetry and a non-invasive procedure in order to generate a final accurate model. In the end detailed results are presented, demonstrating the improvement of the final model, and how the proposed sensor fusion ensure a pre-specified level of accuracy.

  9. The Journal Synthesizing Activity.

    ERIC Educational Resources Information Center

    Garber, Zev

    The journal synthesizing activity is intended to combine aspects of the formal essay with that of a diary. Activities associated with lecture topics are written up as short journal entries of approximately five typewritten pages and are turned in during the weekly class session at which the related topic is being discussed. The journal project…

  10. Wisdom, Intelligence & Creativity Synthesized

    ERIC Educational Resources Information Center

    Sternberg, Robert J.

    2009-01-01

    How is it that smart administrators who want to do a good job often find themselves in situations that degenerate into confrontation and, ultimately, termination? In this article, the author discusses why in terms of a model of leadership--which he refers to it as WICS, an acronym for wisdom, intelligence and creativity synthesized. He describes…

  11. Synthesized night vision goggle

    NASA Astrophysics Data System (ADS)

    Zhou, Haixian

    2000-06-01

    A Synthesized Night Vision Goggle that will be described int his paper is a new type of night vision goggle with multiple functions. It consists of three parts: main observing system, picture--superimposed system (or Cathode Ray Tube system) and Charge-Coupled Device system.

  12. High-resolution digital elevation models of the Flade Iceblink feature in NE Greenland

    NASA Astrophysics Data System (ADS)

    Willis, M. J.; Juntunen, T.; Porter, C. C.; Morin, P. J.

    2013-12-01

    We produce a time series of high-resolution digital elevation models (DEM) to examine the recent evolution of an 8.7 km2 sub-glacial lake collapse feature near the southern summit of the 8500 km2 Flade Isblink Ice Cap (FIIC) in northeastern Greenland [Figure 1]. Visible imagery from the MODerate-resolution Imaging Spectroradiometer (MODIS) indicates the collapse occurred between August 16th and September 6th, 2011 at the site of a recurring moulin. DEMs are extracted using the NASA Ames Stereo Pipeline for the period between June 2012 and late 2013 from 0.5 m resolution along-track stereo image pairs available via the NGA commercial imagery program. The DEMs are compared to a 1996 ERS InSAR derived DEM [Palmer et al., 2010], and to a contemporary airborne laser altimeter swath flown by NASA Icebridge in mid-April 2013 to derive the volume of the feature and the uncertainties on the high-resolution DEMs. The 'mitten' shaped feature is bounded by crevasses on three sides, with a shallow ramp to the south. It is ~70 m deep, 3.7 km north-to-south and 3 km east-to-west and has a volume of ~0.3 km3. Ice penetrating radar from a nearby Icebridge mission in May 2011, indicates the ice is approximately 550 m thick and that the bed is very flat and smooth about 1 km to the southeast of the feature. The nearby bed topography, local geology and lack of recorded seismicity in the area indicate it is unlikely that the feature is the result of either subglacial volcanic activity or the collapse of a limestone karst feature below the ice cap - the neighboring Princess Elizabeth Alps are composed of 420 Ma Caledonide fold belt gneisses. The presence of recurring supraglacial meltwater streams and drainage into the feature, its rapid formation and its steep sided nature instead suggest that it formed during the rapid drainage of a sub-glacial lake - which is, as far as we are aware, the first recorded instance of such an occurrence in Greenland. Meltwater observed using 250 m

  13. Comparison of analog and digital correlation methods suitable for ultrasonic structural health and load monitoring based on high temporal resolution

    NASA Astrophysics Data System (ADS)

    Birkelbach, Gerhard; Grill, Wolfgang

    2012-04-01

    Ultrasonic load and structural health monitoring schemes, based on high temporal resolution of the transport times of ultrasound, have lately been refined such that the achievable temporal resolution can reach 1 ps even for center frequencies in the lower MHz-regime. Whereas this technique was initiated with signal processing based on digitization and subsequent correlation by software controlled digital processing of the data, equipment has lately been designed and manufactured, allowing rather universal processing of low level analog signals by analog based correlations, employing digital references converted to respective analog signals. The signal and data processing schemes are presented and illustrated with experimental results. The advantages and disadvantages of both methods are discussed, including the limiting effects concerning restrictions given by technological and theoretical aspects. Basic features are demonstrated based on the actually developed and adapted instrumentation including software based operations for both principles of signal and data processing. Even though these methods are also used in ultrasonic imaging, the range of applications presented here focuses dominantly on ultrasonic structural health and load monitoring with bulk and guided acoustic waves.

  14. Evaluation of Microstructure and Mechanical Properties of Nano-Y2O3-Dispersed Ferritic Alloy Synthesized by Mechanical Alloying and Consolidated by High-Pressure Sintering

    NASA Astrophysics Data System (ADS)

    Karak, Swapan Kumar; Dutta Majumdar, J.; Witczak, Zbigniew; Lojkowski, Witold; Ciupiński, Łukasz; Kurzydłowski, K. J.; Manna, Indranil

    2013-06-01

    In this study, an attempt has been made to synthesize 1.0 wt pct nano-Y2O3-dispersed ferritic alloys with nominal compositions: 83.0 Fe-13.5 Cr-2.0 Al-0.5 Ti (alloy A), 79.0 Fe-17.5 Cr-2.0 Al-0.5 Ti (alloy B), 75.0 Fe-21.5 Cr-2.0 Al-0.5 Ti (alloy C), and 71.0 Fe-25.5 Cr-2.0 Al-0.5 Ti (alloy D) steels (all in wt pct) by solid-state mechanical alloying route and consolidation the milled powder by high-pressure sintering at 873 K, 1073 K, and 1273 K (600°C, 800°C, and 1000°C) using 8 GPa uniaxial pressure for 3 minutes. Subsequently, an extensive effort has been undertaken to characterize the microstructural and phase evolution by X-ray diffraction, scanning and transmission electron microscopy, and energy dispersive spectroscopy. Mechanical properties including hardness, compressive strength, Young's modulus, and fracture toughness were determined using micro/nano-indentation unit and universal testing machine. The present ferritic alloys record extraordinary levels of compressive strength (from 1150 to 2550 MPa), Young's modulus (from 200 to 240 GPa), indentation fracture toughness (from 3.6 to 15.4 MPa√m), and hardness (from13.5 to 18.5 GPa) and measure up to 1.5 through 2 times greater strength but with a lower density (~7.4 Mg/m3) than other oxide dispersion-strengthened ferritic steels (<1200 MPa) or tungsten-based alloys (<2200 MPa). Besides superior mechanical strength, the novelty of these alloys lies in the unique microstructure comprising uniform distribution of either nanometric (~10 nm) oxide (Y2Ti2O7/Y2TiO5 or un-reacted Y2O3) or intermetallic (Fe11TiY and Al9.22Cr2.78Y) particles' ferritic matrix useful for grain boundary pinning and creep resistance.

  15. Towards semantic-driven high-content image analysis: an operational instantiation for mitosis detection in digital histopathology.

    PubMed

    Racoceanu, D; Capron, F

    2015-06-01

    This study concerns a novel symbolic cognitive vision framework emerged from the Cognitive Microscopy (MICO(1)) initiative. MICO aims at supporting the evolution towards digital pathology, by studying cognitive clinical-compliant protocols involving routine virtual microscopy. We instantiate this paradigm in the case of mitotic count as a component of breast cancer grading in histopathology. The key concept of our approach is the role of the semantics as driver of the whole slide image analysis protocol. All the decisions being taken into a semantic and formal world, MICO represents a knowledge-driven platform for digital histopathology. Therefore, the core of this initiative is the knowledge representation and the reasoning. Pathologists' knowledge and strategies are used to efficiently guide image analysis algorithms. In this sense, hard-coded knowledge, semantic and usability gaps are to be reduced by a leading, active role of reasoning and of semantic approaches. Integrating ontologies and reasoning in confluence with modular imaging algorithms, allows the emergence of new clinical-compliant protocols for digital pathology. This represents a promising way to solve decision reproducibility and traceability issues in digital histopathology, while increasing the flexibility of the platform and pathologists' acceptance, the one always having the legal responsibility in the diagnosis process. The proposed protocols open the way to increasingly reliable cancer assessment (i.e. multiple slides per sample analysis), quantifiable and traceable second opinion for cancer grading, and modern capabilities for cancer research support in histopathology (i.e. content and context-based indexing and retrieval). Last, but not least, the generic approach introduced here is applicable for number of additional challenges, related to molecular imaging and, in general, to high-content image exploration.

  16. High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

    NASA Astrophysics Data System (ADS)

    Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

    2013-06-01

    This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

  17. Low temperature chemically synthesized rutile TiO2 photoanodes with high electron lifetime for organic dye-sensitized solar cells.

    PubMed

    Ambade, Swapnil B; Ambade, Rohan B; Mane, Rajaram S; Lee, Go-Woon; Shaikh, ShoyebMohamad F; Patil, Supriya A; Joo, Oh-Shim; Han, Sung-Hwan; Lee, Soo-Hyoung

    2013-04-11

    Electron lifetime in mesoporous nanostructured rutile TiO2 photoanodes, synthesized via a simple, cost-effective, low temperature (50-55 °C) wet chemical process, annealed at 350 °C for 1 h and not employing any sprayed TiO2 compact layer, was successfully tailored with 0.2 mM TiCl4 surface treatment that resulted in light to electric power conversion efficiency up to 4.4%.

  18. High-speed four-color infrared digital imaging for studying in-cylinder processes in a DI diesel engine

    NASA Astrophysics Data System (ADS)

    Rhee, K. T.

    1995-07-01

    The study was to investigate in-cylinder events of a direct injection-type diesel engine by using a new high-speed infrared (IR) digital imaging systems for obtaining information that was difficult to achieve by the conventional devices. For this, a new high-speed dual-spectra infrared digital imaging system was developed to simultaneously capture two geometrically identical (in respective spectral) sets of IR images having discrete digital information in a (64x64) matrix at rates as high as over 1,800 frames/sec each with exposure period as short as 20 micron sec. At the same time, a new advanced four-color W imaging system was constructed. The first two sets of spectral data were the radiation from water vapor emission bands to compute the distributions of temperature and specie in the gaseous mixture and the remaining two sets of data were to find the instantaneous temperature distribution over the cylinder surface. More than eight reviewed publications have been produced to report many new findings including: Distributions of Water Vapor and Temperature in a Flame; End Gas Images Prior to Onset of Knock; Effect of MTBE on Diesel Combustion; Impact of Oxygen Enrichment on In-cylinder Reactions; Spectral IR Images of Spray Plume; Residual Gas Distribution; Preflame Reactions in Diesel Combustion; Preflame Reactions in the End Gas of an SI Engine; Postflame Oxidation; and Liquid Fuel Layers during Combustion in an SI Engine. In addition, some computational analysis of diesel combustion was performed using KIVA-II program in order to compare results from the prediction and the measurements made using the new IR imaging diagnostic tool.

  19. IDENTIFYING HIGH-METALLICITY M GIANTS AT INTRAGROUP DISTANCES WITH SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Palladino, Lauren E.; Holley-Bockelmann, Kelly; Morrison, Heather; Durrell, Patrick R.; Feldmeier, John; Ciardullo, Robin; Wade, Richard A.; Davy Kirkpatrick, J.; Lowrance, Patrick E-mail: k.holley@vanderbilt.edu

    2012-06-15

    Tidal stripping and three-body interactions with the central supermassive black hole may eject stars from the Milky Way. These stars would comprise a set of 'intragroup' stars that trace the past history of interactions in our galactic neighborhood. Using the Sloan Digital Sky Survey DR7, we identify candidate solar-metallicity red giant intragroup stars using color cuts that are designed to exclude nearby M and L dwarfs. We present 677 intragroup candidates that are selected between 300 kpc and 2 Mpc, and are either the reddest intragroup candidates (M7-M10) or are L dwarfs at larger distances than previously detected.

  20. A digital miniature x-ray tube with a high-density triode carbon nanotube field emitter

    NASA Astrophysics Data System (ADS)

    Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Kim, Jae-Woo; Ahn, Seungjoon; Song, Yoon-Ho

    2013-01-01

    We have fabricated a digital miniature x-ray tube (6 mm in diameter and 32 mm in length) with a high-density triode carbon nanotube (CNT) field emitter for special x-ray applications. The triode CNT emitter was densely formed within a diameter of below 4 mm with the focusing-functional gate. The brazing process enables us to obtain and maintain a desired vacuum level for the reliable electron emission from the CNT emitters after the vacuum packaging. The miniature x-ray tube exhibited a stable and reliable operation over 250 h in a pulse mode at an anode voltage of above 25 kV.