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Sample records for digitally synthesized high

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

    NASA Astrophysics Data System (ADS)

    Ling, Yuan; Qiang, Zhang; Yin, Shi

    2015-06-01

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

  2. A high-performance MUX-direct digital frequency synthesizer with quarter ROMs

    NASA Astrophysics Data System (ADS)

    Zhikun, Hao; Qiang, Zhang; Weining, Ni; Yin, Shi

    2012-01-01

    This paper presents a detailed description of a high-performance direct digital frequency synthesizer (DDFS) using optimized quarter ROMs. To improve the working frequency and spectral purity, an original quarter ROMs structure in 0.13 μm CMOS is brought forward and implemented. The working frequency is increased by 40% compared with Yuan Ling's method[1] of implementing a segmented DAC based DDFS. It has been implemented in 0.13 μm CMOS technology. The DDFS has a resolution of 10 bits with a measured SFDR 54 dBc. Its maximum operating frequency is 1.2 GHz by using six pipelining stages. Analytical investigation of improving spectral performances by using dual-slope approximation and pipeline is also presented.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

    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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Detoma, E.; Stern, A.

    1993-06-01

    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.

  8. Digital frequency synthesizer for radar astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, R.; Satorius, E.; Robinett, L.; Olson, E.

    1990-01-01

    The digital frequency synthesizer (DFS) is an integral part of the programmable local oscillator (PLO) which is being developed for the NASA's Deep Space Network (DSN) and radar astronomy. Here, the theory of operation and the design of the DFS are discussed, and the design parameters in application for the Goldstone Solar System Radar (GSSR) are specified. The spectral purity of the DFS is evaluated by analytically evaluating the output spectrum of the DFS. A novel architecture is proposed for the design of the DFS with a frequency resolution of 1/2(exp 48) of the clock frequency (0.35 mu Hz at 100 MHz), a phase resolution of 0.0056 degrees (16 bits), and a frequency spur attenuation of -96 dBc.

  9. 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.

  10. 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…

  11. 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. PMID:24892092

  12. 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

  13. 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).

  14. 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.

  15. 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.

  16. A 4 GHz 32 bit direct digital frequency synthesizer based on a novel architecture

    NASA Astrophysics Data System (ADS)

    Jin, Wu; Jianwu, Chen; Danyu, Wu; Lei, Zhou; Fan, Jiang; Zhi, Jin; Xinyu, Liu

    2013-11-01

    This paper presents a novel direct digital frequency synthesizer (DDFS) architecture based on nonlinear DAC coarse quantization and the ROM-based piecewise approximation method, which has the advantages of high speed, low power and low hardware resources. By subdividing the sinusoid into a collection of phase segments, the same initial value of each segment is realized by a nonlinear DAC. The ROM is decomposed with a coarse ROM and fine ROM using the piecewise approximation method. Then, the coarse ROM stores the offsets between the initial value of the common segment and the initial value of each line in the same segment. Meanwhile, the fine ROM stores the differences between the line values and the initial value of each line. A ROM compression ratio of 32 can be achieved in the case of 11 bit phase and 9 bit amplitude. Based on the above method, a prototype chip was fabricated using 1.4 μm GaAs HBT technology. The measurement shows an average spurious-free dynamic range (SFDR) of 45 dBc, with the worst SFDR only 40.07 dBc at a 4.0 GHz clock. The chip area is 4.6 × 3.7 mm2 and it consumes 7 W from a -4.9 V power supply.

  17. Multilayer graphane synthesized under high hydrogen pressure

    DOE PAGESBeta

    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.; et al

    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

  18. 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.

  19. Method for Synthesizing Extremeley High Temperature Melting Materials

    SciTech Connect

    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.

  20. Method for synthesizing extremely high-temperature melting materials

    SciTech Connect

    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.

  1. Method For Synthesizing Extremely High-Temperature Melting Materials

    SciTech Connect

    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.

  2. 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.

  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. A 0.8-4.2 GHz monolithic all-digital PLL based frequency synthesizer for wireless communications

    NASA Astrophysics Data System (ADS)

    Yuanxin, Zhao; Yuanpei, Gao; Wei, Li; Ning, Li; Junyan, Ren

    2015-01-01

    A 0.8-4.2 GHz monolithic all-digital PLL based frequency synthesizer for wireless communications is successfully realized by the 130 nm CMOS process. A series of novel methods are proposed in this paper. Two band DCOs with high frequency resolution are utilized to cover the frequency band of interest, which is as wide as 2.5 to 5 GHz. An overflow counter is proposed to prevent the “pulse-swallowing” phenomenon so as to significantly reduce the locking time. A NTW-clamp digital module is also proposed to prevent the overflow of the loop control word. A modified programmable divider is presented to prevent the failure operation at the boundary. The measurement results show that the output frequency range of this frequency synthesizer is 0.8-4.2 GHz. The locking time achieves a reduction of 84% at 2.68 GHz. The best in-band and out-band phase noise performances have reached -100 dBc/Hz, and -125 dBc/Hz respectively. The lowest reference spur is -58 dBc.

  6. High-speed digital project, HSD test capability

    SciTech Connect

    Markley, R.E.; Elarton, J.L.; Allen, C.T.

    1994-04-01

    Establishing a high-speed digital (HSD) test capability for the Digital Waveform Synthesizer (DWS) multichip module (MCM) has required the development of several areas: a detailed test plan for the MCM; design, fabrication and prove-in of the high-speed test console; and the specification, design, and development of the high-speed test and environmental conditioning interface to the DWS. These development activities have been successfully completed at the Allied Signal Inc., Kansas City Division (KCD), and the test capability described herein is currently supporting DWS MCM testing and can be adapted to similar HSD module testing.

  7. 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. PMID:26429495

  8. 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.

  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. PMID:23251230

  10. 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

  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

    2013-01-01

    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

  12. 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

  13. 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.

  14. A power scalable PLL frequency synthesizer for high-speed Δ—Σ ADC

    NASA Astrophysics Data System (ADS)

    Siyang, Han; Baoyong, Chi; Xinwang, Zhang; Zhihua, Wang

    2014-08-01

    A 35-130 MHz/300-360 MHz phase-locked loop frequency synthesizer for Δ—Σ analog-to-digital converter (ADC) in 65 nm CMOS is presented. The frequency synthesizer can work in low phase-noise mode (300-360 MHz) or in low-power mode (35-130 MHz) to satisfy the ADC's requirements. To switch between these two modes, a high frequency GHz LC VCO followed by a divided-by-four frequency divider and a low frequency ring VCO followed by a divided-by-two frequency divider are integrated on-chip. The measured results show that the frequency synthesizer achieves a phase-noise of -132 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 1.12 ps with 1.74 mW power consumption from a 1.2 V power supply in low phase-noise mode. In low-power mode, the frequency synthesizer achieves a phase-noise of -112 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 7.23 ps with 0.92 mW power consumption from a 1.2 V power supply.

  15. 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.

  16. 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.

  17. 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

    2013-02-01

    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. PMID:23354052

  18. High Density Digital Data Storage System

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D., II; Gray, David L.; Rowland, Wayne D.

    1991-01-01

    The High Density Digital Data Storage System was designed to provide a cost effective means for storing real-time data from the field-deployable digital acoustic measurement system. However, the high density data storage system is a standalone system that could provide a storage solution for many other real time data acquisition applications. The storage system has inputs for up to 20 channels of 16-bit digital data. The high density tape recorders presently being used in the storage system are capable of storing over 5 gigabytes of data at overall transfer rates of 500 kilobytes per second. However, through the use of data compression techniques the system storage capacity and transfer rate can be doubled. Two tape recorders have been incorporated into the storage system to produce a backup tape of data in real-time. An analog output is provided for each data channel as a means of monitoring the data as it is being recorded.

  19. 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.

  20. 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.

  1. 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).

  2. High-performance Ni3Al synthesized from composite powders

    NASA Astrophysics Data System (ADS)

    Chiou, Wen-Chih; Hu, Chen-Ti

    1994-05-01

    Specimens of Ni3Al + B of high density (>99.3 Pct RD) and relatively large dimension have been synthesized from composite powders through processes of replacing plating and electroless Ni-B plating on Al powder, sintering, and thermal-mechanical treatment. The uniformly coated Ni layer over fine Al or Ni core particles constituting these coating/core composite powders has advantages such as better resistance to oxidation relative to pure Al powder, a greater green density as a compacted powder than prealloyed powder, the possibility of atomically added B to the material by careful choice of a suitable plating solution, and avoidance of the expensive powder metallurgy (PM) equipment such as a hot isostatic press (HIP), hot press (HP), etc. The final Ni3Al + B product is made from Ni-B-Al and Ni-B-Ni mixed composite powders by means of traditional PM processes such as compacting, sintering, rolling, and annealing, and therefore, the dimensions of the product are not constrained by the capacity of an HIP or HP. The properties of Ni3Al composite powder metallurgy (CPM) specimens tested at room temperature have been obtained, and comparison with previous reports is conducted. A tensile elongation of about 16 Pct at room temperature was attained.

  3. Bridging the gap between research and practice: The development of a digital library of research syntheses.

    PubMed

    Barroso, Julie; Edlin, April; Sandelowski, Margarete; Lambe, Camille

    2006-01-01

    This article describes the development of a digital library as a resource for clinicians and researchers working with women with HIV infection. We wanted to find a new way of communicating the findings from the 114 studies that we used as the method case. The development of the SandBar Digital Library (http://sonweb.unc.edu/sandbar), a product of a 5-year project to develop the analytic techniques for qualitative metasynthesis, is described from its inception, including analyses of the potential users and how they might use such a resource. The Digital Library evolved over a 3-year period, with continuous feedback from a group of researchers and clinicians who are also experts in the care of HIV-positive people. It provides a concise and comprehensive compilation of findings in two major areas of concern for the seropositive women who were the participants in the studies: motherhood and stigma. PMID:16554692

  4. 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.

  5. High-Density Digital Data Storage System

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D.; Gray, David L.

    1995-01-01

    High-density digital data storage system designed for cost-effective storage of large amounts of information acquired during experiments. System accepts up to 20 channels of 16-bit digital data with overall transfer rates of 500 kilobytes per second. Data recorded on 8-millimeter magnetic tape in cartridges, each capable of holding up to five gigabytes of data. Each cartridge mounted on one of two tape drives. Operator chooses to use either or both of drives. One drive used for primary storage of data while other can be used to make a duplicate record of data. Alternatively, other drive serves as backup data-storage drive when primary one fails.

  6. High-intensity attosecond high-order harmonic generation driven by a synthesized laser field

    SciTech Connect

    Zeng Zhinan; Li Ruxin; Xie Xinhua; Xu Zhizhan

    2004-11-01

    The scheme of high-intensity attosecond high-order harmonic generation driven by a synthesized laser field is proposed. The synthesized laser field is obtained by an appropriate superposition of a few-cycle laser pulse and a relatively long pulse of several tens of femtoseconds. Calculated results show that the intensity of the attosecond high-order harmonic pulse in helium driven by the synthesized laser field with a 8.8x10{sup 13} W/cm{sup 2}/5 fs laser pulse and a 3.51x10{sup 14} W/cm{sup 2}/50 fs laser pulse is several orders of magnitude higher than that driven by a single 8.8x10{sup 13} W/cm{sup 2}/5 fs laser pulse, and it is even stronger than that driven by a single 7.9x10{sup 14} W/cm{sup 2}/5 fs laser pulse, although the single and the synthesized pulses have the same peak electric-field strength.

  7. Performance Analysis of a Digital Image Synthesizer as a Counter-Measure Against Inverse Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    LeDantec, Fernando A.

    2002-09-01

    This thesis is concerned with the development of a model to analyze a Digital Image Synthesizer (DIS) integrated circuit designed to create false target images to deceive Inverse Synthetic Aperture Radar (ISAR). The DIS is able to recreate the scattering effect of a moving target by using appropriate phase and gain modulations on an intercepted ISAR chirp signal before retransmitting it with the proper time delay. The DIS signal processing and the ISAR compression of the modulated return are modeled to examine the range-Doppler profile of a synthesized false target image. The image is representative of the image that would appear on an ISAR display. ISAR image quality is used to evaluate different DIS architectures and bit formats. Evaluation of the image quality is based on the deviation from an infinite resolution false target image. The results obtained from evaluating different DIS architectures indicate that the design is tolerant of significant quantization errors. The model is used to validate the architecture of the integrated circuit being fabricated. Finally, various different ISAR integration times and pulse repetition frequencies are used to confirm the integrity of the model.

  8. High-speed Digital Baseband Mixer

    NASA Technical Reports Server (NTRS)

    Chan, F. P.; Quirk, M. P.; Jurgens, R. F.

    1985-01-01

    The feasibility of designing a digital, complex, baseband mixer with a 50 MHz sampling rate is explored. The baseband filter must provide passbands with linear phase response to minimize intersymbol interference. The effects of signal quantization, filter coefficient quantization, dynamic range, filter response characteristics, and the performance of the mixer when used for cross correlation and autocorrelation pulse detection techniques are discussed. This filter was designed for use in the high speed data acquisition system (HSDAS), an advanced experimental system in the Deep Space Network.

  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. Eutectic Syntheses of Graphitic Carbon with High Pyrazinic Nitrogen Content.

    PubMed

    Fechler, Nina; Zussblatt, Niels P; Rothe, Regina; Schlögl, Robert; Willinger, Marc-Georg; Chmelka, Bradley F; Antonietti, Markus

    2016-02-10

    Mixtures of phenols/ketones and urea show eutectic behavior upon gentle heating. These mixtures possess liquid-crystalline-like phases that can be processed. The architecture of phenol/ketone acts as structure-donating motif, while urea serves as melting-point reduction agent. Condensation at elevated temperatures results in nitrogen-containing carbons with remarkably high nitrogen content of mainly pyrazinic nature. PMID:26178584

  11. 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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26311616

  13. New Phases of C60 Synthesized at High Pressure

    NASA Astrophysics Data System (ADS)

    Iwasa, Y.; Arima, T.; Fleming, R. M.; Siegrist, T.; Zhou, O.; Haddon, R. C.; Rothberg, L. J.; Lyons, K. B.; Carter, H. L., Jr.; Hebard, A. F.; Tycko, R.; Dabbagh, G.; Krajewski, J. J.; Thomas, G. A.; Yagi, T.

    1994-06-01

    The fullerene C60 can be converted into two different structures by high pressure and temperature. They are metastable and revert to pristine C60 on reheating to 300^circC at ambient pressure. For synthesis temperatures between 300^circ and 400^circC and pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with a lattice parameter a_o = 13.6 angstroms. When treated at 500^circ to 800^circC at the same pressure, C60 transforms into a rhombohedral structure with hexagonal lattice parameters of a_o = 9.22 angstroms and c_o = 24.6 angstroms. The intermolecular distance is small enough that a chemical bond can form, in accord with the reduced solubility of the pressure-induced phases. Infrared, Raman, and nuclear magnetic resonance studies show a drastic reduction of icosahedral symmetry, as might occur if the C60 molecules are linked.

  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-frame-rate digital radiographic videography

    NASA Astrophysics Data System (ADS)

    King, Nicholas S. P.; Cverna, Frank H.; Albright, Kevin L.; Jaramillo, Steven A.; Yates, George J.; McDonald, Thomas E.; Flynn, Michael J.; Tashman, Scott

    1994-10-01

    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.

  16. 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.

  17. Composite Digital Terrain Models: Synthesizing Aerial and Terrestrial LiDAR with Conventional Survey Data to Monitor Sediment Transport Through the Sunol Dam Removal Site

    NASA Astrophysics Data System (ADS)

    Storesund, R.; Minear, T.; Saleh, R.

    2007-12-01

    In 2006, the San Francisco Public Utilities Commission removed Sunol dam, located on Alameda Creek, near San Francisco California. The primary goals of the project were to improve fish passage, restore a self- sustaining population of steelhead to the watershed, and eliminate an existing public safety hazard. Approximately 28,300 cubic meters of sand and gravel-sized sediment had accumulated upstream of the dam and was left in place to move downstream naturally over a period of several decades. To create a baseline for future monitoring of sediment transport through the dam area, a combination of Aerial LiDAR, Terrestrial LiDAR, and conventional survey data was compiled and synthesized to generate a three dimensional digital model of the study area both upstream and downstream of the damsite. The primary survey method for characterization of above ground topography was Terrestrial LiDAR, with an approximate point spacing of centimeters. In submerged areas conventional survey techniques were used to augment the Aerial and Terrestrial LiDAR data sets. We found this approach to be effective in developing a high accuracy-high detail sediment volume model from which sediment transport can be monitored and modeled.

  18. 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,…

  19. Digital controller for high pressure rocket engine.

    NASA Technical Reports Server (NTRS)

    Thompson, Z.; Cummings, W. J.; Hall, D. M.

    1972-01-01

    Description of a general approach for the design of an adaptive digital control system for liquid bipropellant rocket engines. The technique employs linearized transfer functions derived from perturbations of an engine simulation. The linear models serve as a basis on which to develop candidate closed-loop control laws quickly and economically.

  20. 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.

  1. 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.

  2. 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.

  3. High-sensitivity high-resolution dual-function signal and time digitizer

    NASA Astrophysics Data System (ADS)

    Sarwana, Saad; Gupta, Deepnarayan; Kirichenko, Alex F.; Oku, Takayuki; Otani, Chiko; Sato, Hiromi; Shimizu, Hirohiko M.

    2002-03-01

    We have developed a dual-function high sensitivity/high-resolution digitizer. It consists of a superconducting digital integrated circuit, which can operate both as a time-to-digital converter (TDC) and a flux counting analog-to-digital converter (ADC). The TDC has a 30 ps multihit time resolution. The ADC has been designed with a superconducting quantum interference device based detector for a 1 μA full scale range. This digitizer is extremely useful in many applications, e.g., for time-of-flight measurements, or as a radiation resistant, low-noise, low-power ADC for detector readout.

  4. 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…

  5. High-accuracy function synthesizer circuit with applications in signal processing

    NASA Astrophysics Data System (ADS)

    Popa, Cosmin

    2012-12-01

    An original low-voltage current-mode high-accuracy function synthesizer circuit will be presented, allowing to implement a multitude of continuous mathematical functions. The dynamic range is strongly extended as a result of the superior-order approximation of the implemented functions. The current-mode operation and the independence of the circuit performances on technological parameters are responsible for an additional improvement of structure accuracy. The advantages of reduced design costs per function represent an immediate consequence of the multiple functions realized by the proposed structure. The approximation error of the original function synthesizer circuit is 0.3% for an extended range of the input signal. The function synthesizer is designed for implementing in 0.18 μm CMOS technology and it is supplied at 1 V. An original application of the proposed function synthesizer circuit is represented by a new fourth-order approximation exponential function generator, having a dynamic range of approximately 33 dB, for an error smaller than 1 dB.

  6. 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.

  7. 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. PMID:23842235

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

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Bi, Xianghong; Chen, Haibin; Wu, Jingshen

    2014-05-01

    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.

  9. 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.

  10. 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.

  11. High-quality gene assembly directly from unpurified mixtures of microarray-synthesized oligonucleotides

    PubMed Central

    Borovkov, Alex Y.; Loskutov, Andrey V.; Robida, Mark D.; Day, Kristen M.; Cano, Jose A.; Le Olson, Tien; Patel, Hetal; Brown, Kevin; Hunter, Preston D.; Sykes, Kathryn F.

    2010-01-01

    To meet the growing demand for synthetic genes more robust, scalable and inexpensive gene assembly technologies must be developed. Here, we present a protocol for high-quality gene assembly directly from low-cost marginal-quality microarray-synthesized oligonucleotides. Significantly, we eliminated the time- and money-consuming oligonucleotide purification steps through the use of hybridization-based selection embedded in the assembly process. The protocol was tested on mixtures of up to 2000 oligonucleotides eluted directly from microarrays obtained from three different chip manufacturers. These mixtures containing <5% perfect oligos, and were used directly for assembly of 27 test genes of different sizes. Gene quality was assessed by sequencing, and their activity was tested in coupled in vitro transcription/translation reactions. Genes assembled from the microarray-eluted material using the new protocol matched the quality of the genes assembled from >95% pure column-synthesized oligonucleotides by the standard protocol. Both averaged only 2.7 errors/kb, and genes assembled from microarray-eluted material without clonal selection produced only 30% less protein than sequence-confirmed clones. This report represents the first demonstration of cost-efficient gene assembly from microarray-synthesized oligonucleotides. The overall cost of assembly by this method approaches 5¢ per base, making gene synthesis more affordable than traditional cloning. PMID:20693531

  12. 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…

  13. Processor for high-density digital tape-recorded signals

    NASA Technical Reports Server (NTRS)

    Ashlock, J. C.

    1973-01-01

    Linear filter and detection theory can bear on problem of reconstructing recorded bit stream. Problem can be taken from realm of nonlinear problems even though basic record process is still recognized as highly nonlinear. Digital tape recorder can be modeled as particular type of linear communication channel with intersymbol interference.

  14. Highly accelerated life testing for the 1210 Digital Ruggedized Display

    NASA Astrophysics Data System (ADS)

    Becker, Bruce; Phillips, Ruth

    1998-09-01

    The 1210 Digital Ruggedized Display (1210 DRD) was designed and built for a harsh military environment. The 1210 DRD uses a single 1280 X 1024 Digital Micromirror Device (DMDTM) as a reflective image source. Through the use of Highly Accelerated Life Testing we have verified and validated the 1210 DRD through rigorous thermal, vibration, and combined environment testing. The results prove the DMD-based 1210 DRD to be a very rugged display that can meet and exceed the requirements of displays used in military applications.

  15. 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.

  16. Digital colloids: reconfigurable clusters as high information density elements.

    PubMed

    Phillips, Carolyn L; Jankowski, Eric; Krishnatreya, Bhaskar Jyoti; Edmond, Kazem V; Sacanna, Stefano; Grier, David G; Pine, David J; Glotzer, Sharon C

    2014-10-14

    Through the design and manipulation of discrete, nanoscale systems capable of encoding massive amounts of information, the basic components of computation are open to reinvention. These components will enable tagging, memory storage, and sensing in unusual environments - elementary functions crucial for soft robotics and "wet computing". Here we show how reconfigurable clusters made of N colloidal particles bound flexibly to a central colloidal sphere have the capacity to store an amount of information that increases as O(N ln(N)). Using Brownian dynamics simulations, we predict dynamical regimes that allow for information to be written, saved, and erased. We experimentally assemble an N = 4 reconfigurable cluster from chemically synthesized colloidal building blocks, and monitor its equilibrium dynamics. We observe state switching in agreement with simulations. This cluster can store one bit of information, and represents the simplest digital colloid. PMID:25034966

  17. High-precision digital charge-coupled device TV system

    NASA Astrophysics Data System (ADS)

    Vishnevsky, Grigory I.; Ioffe, S. A.; Berezin, V. Y.; Rybakov, M. I.; Mikhaylov, A. V.; Belyaev, L. V.

    1991-06-01

    In certain test, measurement, and research applications of CCD TV systems, the greater accuracy than usual 8-bit frame-grabbers can provide is demanded without the system being too expensive. The paper presents the concept and features of the high-precision low-cost digital CCD TV system intended for obtaining 12-bit monochrome images of immobile or relatively slow moving objects. The increase in accuracy is achieved by the specific digitization procedure -- one column per frame, which combines the benefits of a slow A/D converter with real-time TV imaging compatibility. To reduce speed restrictions on sample- and-hold circuits, a zoomed pixel read out cycle, corresponding to the pixel to be digitized, is proposed. The system provides great flexibility in choice of integration times and readout rates by means of a programmable readout sequencer, and is easily adaptable to various user demands and CCDs types.

  18. 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.

  19. High-speed digital signal normalization for feature identification

    NASA Technical Reports Server (NTRS)

    Ortiz, J. A.; Meredith, B. D.

    1983-01-01

    A design approach for high speed normalization of digital signals was developed. A reciprocal look up table technique is employed, where a digital value is mapped to its reciprocal via a high speed memory. This reciprocal is then multiplied with an input signal to obtain the normalized result. Normalization improves considerably the accuracy of certain feature identification algorithms. By using the concept of pipelining the multispectral sensor data processing rate is limited only by the speed of the multiplier. The breadboard system was found to operate at an execution rate of five million normalizations per second. This design features high precision, a reduced hardware complexity, high flexibility, and expandability which are very important considerations for spaceborne applications. It also accomplishes a high speed normalization rate essential for real time data processing.

  20. 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.

  1. Syntheses of marchantins C, O and P as promising highly bioactive compounds.

    PubMed

    Speicher, Andreas; Holz, Judith; Hoffmann, Alexandra

    2011-03-01

    Recently, remarkable microtubule inhibitor and anti-tumor activities of the bis(bibenzyl) marchantin C--isolated from liverworts like Marchantia polymorpha since 1983--were found. In this paper we describe the efficient total synthesis of this subtype of bis(bibenzylic) compounds with two biarylether connections. Two selectively methylated derivatives known as natural compounds marchantin O and P were synthesized for the first time by modification of the arene subunits and can now be considered as promising highly bioactive compounds. PMID:21485281

  2. The influence of high-energy impacts on the microstructure of synthesized metal ceramics

    NASA Astrophysics Data System (ADS)

    Ovcharenko, V. E.; Solonenko, O. P.; Chesnokov, A. E.; Fomin, V. M.

    2012-11-01

    On the example of the metal-ceramic alloy of titanium carbide (TiC) with nickel-chromium (Ni-Cr) binder, the comparative analysis of the influence of different high-energy impacts on the dispersion of the internal structure and phase composition of the synthesized metal ceramics 70 vol % TiC + 30 vol % (Ni-Cr) has been performed for the first time (self-spreading high-temperature synthesis (SSHTS) under pressure, preliminary mechanical activation (MA) of metal components of the initial powder mixture titanium-carbon-nickel-chromium binder, subsequent MA of the whole powder mixture, and intense plastic deformation of the synthesis product). It has been demonstrated that, under intense plastic deformation with extrusion of the high-temperature synthesis product, there a metal-ceramic structure forms containing particles of the nanosized carbide phase of the stoichiometric composition.

  3. Metal-Organic Framework/PVDF Composite Membranes with High H2 Permselectivity Synthesized by Ammoniation.

    PubMed

    Li, Wanbin; Meng, Qin; Zhang, Congyang; Zhang, Guoliang

    2015-05-01

    Herein we report a new ammoniation-based chemical modification strategy for synthesis of continuous and uniform metal-organic framework (MOF)/polyvinylidene fluoride (PVDF) membranes with attractive performance. Ammoniation can promote the support PVDF membrane to produce amino groups, form a nanoparticle structure, and be well cross-linked; therefore, the high-density heterogeneous nucleation sites for MOFs growth were provided and the thermal stability and chemical resistance of composite membranes can be greatly improved. The high-quality layers of representative Cu-BTC and ZIF-8 were synthesized on the chemically modified PVDF membranes. By ammoniation, ZIF-7 can even be grown under harsh synthetic conditions such as in DMF precursor solutions at 403 K. The fabricated MOF/PVDF composite membranes with excellent hollow fiber structures and enhanced structural stability exhibited high H2 permselectivities for H2 /CO2 and H2 /N2 . PMID:25810142

  4. Magnetic nanoparticles for biophysical applications synthesized by high-power physical dispersion

    NASA Astrophysics Data System (ADS)

    Safronov, A. P.; Beketov, I. V.; Tyukova, I. S.; Medvedev, A. I.; Samatov, O. M.; Murzakaev, A. M.

    2015-06-01

    The low cost and high output methods of high-power physical dispersion: the electrical explosion of wire and the laser target evaporation were elaborated for the production of iron oxide magnetic nanoparticles (MNPs) with controlled dispersion parameters and highly reproducible functional properties. The synthesized MNPs were spherical in shape with mean diameter 10 nm and lognormal particle size distribution. The phase composition, shape, particle size and functional properties of MNPs were cross-examined by a variety of contemporary experimental techniques. The phase structure of MNPs corresponds to the inverse spinel of magnetite. Meanwhile, due to the non-equilibrium conditions of the dispersion chemical composition of MNPs is close to maghemite-γ-Fe2O3. Their magnetic properties are reproducible and very close to the single domain superparamagnetic behavior. The stability of the suspensions of these MNPs and their applicability in the biophysical purposes such as magneto-induced heating have been demonstrated.

  5. A Digital Multigate Doppler Method for High Frequency Ultrasound

    PubMed Central

    Qiu, Weibao; Ye, Zongying; Yu, Yanyan; Chen, Yan; Chi, Liyang; Mu, Peitian; Li, Guofeng; Wang, Congzhi; Xiao, Yang; Dai, Jiyan; Sun, Lei; Zheng, Hairong

    2014-01-01

    Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW) Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method. PMID:25061836

  6. A digital multigate Doppler method for high frequency ultrasound.

    PubMed

    Qiu, Weibao; Ye, Zongying; Yu, Yanyan; Chen, Yan; Chi, Liyang; Mu, Peitian; Li, Guofeng; Wang, Congzhi; Xiao, Yang; Dai, Jiyan; Sun, Lei; Zheng, Hairong

    2014-01-01

    Noninvasive visualization of blood flow with high frequency Doppler ultrasound has been extensively used to assess the morphology and hemodynamics of the microcirculation. A completely digital implementation of multigate pulsed-wave (PW) Doppler method was proposed in this paper for high frequency ultrasound applications. Analog mixer was eliminated by a digital demodulator and the same data acquisition path was shared with traditional B-mode imaging which made the design compact and flexible. Hilbert transform based quadrature demodulation scheme was employed to achieve the multigate Doppler acquisition. A programmable high frequency ultrasound platform was also proposed to facilitate the multigate flow visualization. Experimental results showed good performance of the proposed method. Parabolic velocity gradient inside the vessel and velocity profile with different time slots were acquired to demonstrate the functionality of the multigate Doppler. Slow wall motion was also recorded by the proposed method. PMID:25061836

  7. Nanosized tungsten carbide synthesized by a novel route at low temperature for high performance electrocatalysis

    NASA Astrophysics Data System (ADS)

    Yan, Zaoxue; Cai, Mei; Shen, Pei Kang

    2013-04-01

    Tungsten carbide (WC) is a widely used engineering material which is usually prepared at high temperature. A new mechanism for synthesizing nanoscaled WC at ultralow temperature has been discovered. This discovery opens a novel route to synthesize valuable WC and other carbides at a cost-efficient way. The novel formation mechanism is based on an ion-exchange resin as carbon source to locally anchor the W and Fe species. As an intermediate, FeWO4 can be formed at lower temperature, which can be directly converted into WC along with the carbonization of resin. The size of WC can be less than 2 nm. The catalyst made with Pt nanoparticles supported on nanosized WC-GC (WC-graphitized carbon) shows enhanced electrocatalytic activity for oxygen reduction reaction. The result also indicates that the Pt nanoparticles deposited on WC-GC are dominated by Pt (111) plane and shows a mass activity of 257.7 mA mg-1Pt@0.9 V.

  8. Nanosized tungsten carbide synthesized by a novel route at low temperature for high performance electrocatalysis

    PubMed Central

    Yan, Zaoxue; Cai, Mei; Shen, Pei Kang

    2013-01-01

    Tungsten carbide (WC) is a widely used engineering material which is usually prepared at high temperature. A new mechanism for synthesizing nanoscaled WC at ultralow temperature has been discovered. This discovery opens a novel route to synthesize valuable WC and other carbides at a cost-efficient way. The novel formation mechanism is based on an ion-exchange resin as carbon source to locally anchor the W and Fe species. As an intermediate, FeWO4 can be formed at lower temperature, which can be directly converted into WC along with the carbonization of resin. The size of WC can be less than 2 nm. The catalyst made with Pt nanoparticles supported on nanosized WC-GC (WC-graphitized carbon) shows enhanced electrocatalytic activity for oxygen reduction reaction. The result also indicates that the Pt nanoparticles deposited on WC-GC are dominated by Pt (111) plane and shows a mass activity of 257.7 mA mg−1Pt@0.9 V. PMID:23571654

  9. Syntheses of wetland methane emissions at high latitudes: exploring sensitivities to climate change and permafrost thaw.

    NASA Astrophysics Data System (ADS)

    Olefeldt, D.; Turetsky, M. R.

    2014-12-01

    Climate change and associated permafrost thaw has the potential to increase methane emissions from high latitude wetlands, thus amplifying human-caused climate change. Methane monitoring at high latitude wetlands have been carried out since the 1970s, and at this time there are published data from a large number of sites and some individual sites have data that span more than a decade. By synthesizing data both across and within sites it is possible to improve our understanding of environmental and physical controls on methane emissions. It is clear from comparing mean growing season methane emissions across sites that site wetness, soil temperature and vegetation composition have strong and interacting effects. At individual sites it is also evident that soil temperatures and wetness co-vary at inter-annual scales as a result of physical processes, with compounding influences on methane emissions. Further the presence of certain sedge species, often found in fens at high latitudes strongly influence sensitivities to soil temperature and wetness. Shifts in functional relationships as related to ecosystem structure is central for methane emissions at high latitude wetlands, given the hydrological and ecological changes that occur with permafrost thaw and thermokarst landform development. Hence, in order to more accurately project future methane emissions from high latitudes at a pan-arctic scale, it is necessary to include a spatial representation of thermokarst development as well as ecosystem-appropriate functional relationships between emissions and environmental variables.

  10. Highly Luminescent, Water-Soluble Lanthanide Fluorobenzoates: Syntheses, Structures and Photophysics, Part I: Lanthanide Pentafluorobenzoates.

    PubMed

    Kalyakina, Alena S; Utochnikova, Valentina V; Bushmarinov, Ivan S; Ananyev, Ivan V; Eremenko, Igor L; Volz, Daniel; Rönicke, Franziska; Schepers, Ute; Van Deun, Rik; Trigub, Alexander L; Zubavichus, Yan V; Kuzmina, Natalia P; Bräse, Stefan

    2015-12-01

    Highly luminescent, photostable, and soluble lanthanide pentafluorobenzoates have been synthesized and thoroughly characterized, with a focus on Eu(III) and Tb(III) complexes as visible emitters and Nd(III) , Er(III) , and Yb(III) complexes as infrared emitters. Investigation of the crystal structures of the complexes in powder form and as single crystals by using X-ray diffraction revealed five different structural types, including monomeric, dimeric, and polymeric. The local structure in different solutions was studied by using X-ray absorption spectroscopy. The photoluminescence quantum yields (PLQYs) of terbium and europium complexes were 39 and 15 %, respectively; the latter value was increased almost twice by using the heterometallic complex [Tb0.5 Eu0.5 (pfb)3 (H2 O)] (Hpfb=pentafluorobenzoic acid). Due to the effectively utilized sensitization strategy (pfb)(-) →Tb→Eu, a pure europium luminescence with a PLQY of 29 % was achieved. PMID:26489887

  11. 3D SERS Imaging Using Chemically Synthesized Highly Symmetric Nanoporous Silver Microparticles.

    PubMed

    Vantasin, Sanpon; Ji, Wei; Tanaka, Yoshito; Kitahama, Yasutaka; Wang, Mengfan; Wongravee, Kanet; Gatemala, Harnchana; Ekgasit, Sanong; Ozaki, Yukihiro

    2016-07-11

    3D surface-enhanced Raman scattering (SERS) imaging with highly symmetric 3D silver microparticles as a SERS substrate was developed. Although the synthesis method is purely chemical and does not involve lithography, the synthesized nanoporous silver microparticles possess a regular hexapod shape and octahedral symmetry. By using p-aminothiophenol (PATP) as a probe molecule, the 3D enhancement patterns of the particles were shown to be very regular and predictable, resembling the particle shape and exhibiting symmetry. An application to the detection of 3D inhomogeneity in a polymer blend, which relies on the predictable enhancement pattern of the substrate, is presented. 3D SERS imaging using the substrate also provides an improvement in spatial resolution along the Z axis, which is a challenge for Raman measurement in polymers, especially layered polymeric systems. PMID:27240138

  12. Tracking high amplitude auto-oscillations with digital Fresnel holograms.

    PubMed

    Picart, Pascal; Leval, Julien; Piquet, Francis; Boileau, Jean P; Guimezanes, Thomas; Dalmont, Jean-Pierre

    2007-06-25

    Method for tracking vibrations with high amplitude of several hundreds of micrometers is presented. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of a clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece. PMID:19547155

  13. Tracking high amplitude auto-oscillations with digital Fresnel holograms

    NASA Astrophysics Data System (ADS)

    Picart, Pascal; Leval, Julien; Piquet, Francis; Boileau, Jean P.; Guimezanes, Thomas; Dalmont, Jean-Pierre

    2007-06-01

    Method for tracking vibrations with high amplitude of several hundreds of micrometers is presented. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of a clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece.

  14. 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.

  15. 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).

  16. Highly stable digital holographic microscope using Sagnac interferometer.

    PubMed

    Mahajan, Swapnil; Trivedi, Vismay; Vora, Priyanka; Chhaniwal, Vani; Javidi, Bahram; Anand, Arun

    2015-08-15

    Interferometric microscopy has grown into a very potent tool for quantitative phase imaging of biological samples. Among the interfermetric methods, microscopy by digital holography is one of the most effective techniques, especially for studying dynamics of cells. Imaging of cell fluctuations requires digital holographic setups with high temporal stability. Common path setups in which the object and the reference beams encounter the same set of optical elements provide better temporal stability compared to two-beam setups. Here, we present a compact, easy-to-implement, common path digital holographic microscope based on Sagnac interferometer geometry. The microscope is implemented using a diode laser module employing a CCD array or a webcam sensor to record holograms. The system was tested for three-dimensional imaging capability, numerical focusing ability, and temporal stability. Sub-nanometer temporal stability without external vibration isolation components was obtained in both cases. The higher temporal stability makes the microscope compatible to image cell fluctuations, which is demonstrated by imaging the oscillation of the cell membrane of human red blood cells. PMID:26274649

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

    PubMed

    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 m(2)/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/dm(3) 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

  18. 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

  19. High-throughput high-resolution microscopic slide digitization for pathology

    NASA Astrophysics Data System (ADS)

    Beckstead, Jeffrey A.; Dawson, Robert; Feineigle, Patricia A.; Gilbertson, John, Jr.; Hauser, Christopher; McVaugh, Timothy; Palmieri, Francesco; Sholehvar, David; Wetzel, Arthur

    2003-07-01

    Pathologist study tissue samples to determine the presence and nature of diseases. Morphology is a critical component to identifying cellular and tissue structures and the functional changes produced by disease. Technical advances in the field of pathology have primarily been in the areas of tissue preparation and the staining process that enhances the pathologist's identification of these structures. Pathologist's primary tool for diagnosis has remained the same for over a century--the optical microscope. Radiology has made tremendous advances with digitization and the ease of exchange and image analysis that comes with digital data and today's computer technology. Pathology is primed to enter the digital era as well. The major hurdles to wide spread acceptance of conversion to digital pathological imaging have been image resolution, scanner throughput, image file size and image display rates. InterScope Technologies, Inc. has developed a high-throughput, high-resolution microscopic slide digitization system that is well suited for pathological examination and diagnosis. This system is fully automated, captures at 0.3 μm per pixel, and can capture a slide in under 3 minutes, and has the potential to capture much faster. This paper will present the technical challenges associated with digital pathological imaging and how InterScope has addressed these challenges in the development of their digital scanner.

  20. In situ synthesized novel biocompatible titania-chitosan nanocomposites with high surface area and antibacterial activity.

    PubMed

    Kavitha, K; Sutha, S; Prabhu, M; Rajendran, V; Jayakumar, T

    2013-04-01

    A series of titania-chitosan nanocomposites (2:x (0.12, 0.25, 0.5, 1.0 and 2.0g)) were synthesized using in situ sol-gel method and comprehensively characterized using conventional techniques. The resultant particles showed anatase phase, spherical and irregular morphology with particle size of 4.5-10.5nm. Nanocomposites with higher surface area (114-265m(2)/g) and high purity were obtained. The characterized samples were analyzed in 1.5mM simulated body fluid (1.5 SBF) and human gastric adenocarcinoma cell line to explore the bioactivity and biocompatibility. Antibacterial activity against Staphylococcus aureus was also evaluated. The formation of apatite layer on 1.5 SBF-immersed samples confirms the bioactivity of all the nanocomposites. High surface area, appropriate hydroxyapatite formation, specific antibacterial action, increased cell viability, controlled swelling and degrading rate are favorably achieved at 2:1 nanocomposite ratio. This study shows titania-chitosan nanocomposites as the promising biomaterial for orthopedic and tissue engineering applications. PMID:23499117

  1. Nanocrystalline silicon embedded in silicon suboxide synthesized in high-density inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhou, H. P.; Xu, S.; Xu, M.; Xiao, S. Q.; Xiang, Y.

    2015-11-01

    A two-phase material system of nanocrystalline silicon (nc-Si) embedded in a dielectric matrix of silicon suboxide (SiO x ) is fundamentally and technologically significant for the photonic and photovoltaic device such as light emission diode and solar cells. nc-Si in amorphous SiO x has been synthesized by means of the low-frequency (460 kHz) inductively coupled plasma (LFICP) of SiH4  +  CO2  +  H2 without the common route of high hydrogen dilution. The chemical composition, microstructures and optical properties of the complex material system are tuned by the reactive gas flow rate ratio of CO2/SiH4. nc-Si embedded in amorphous SiO x due to the phase separation are observed by means of SEM and TEM characterization tools. The crystalline volume fraction in nc-SiO x :H is determined by the density of the embedded nc-Si particles and the occurrence of the a-SiO x encapsulating shell layer. The bond configuration analysis shows the concurrent oxygenation and dehydrogenation process with the incorporation of oxygen. The underlying mechanism in forming the two-phase complex material system and the phase evolution with the reactive gas flow rate ratio are discussed in terms of the unique features of the utilized high-density LFICP.

  2. 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.

  3. 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.

  4. 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

  5. Replacing 16 mm film cameras with high definition digital cameras

    SciTech Connect

    Balch, K.S.

    1995-12-31

    For many years 16 mm film cameras have been used in severe environments. These film cameras are used on Hy-G automotive sleds, airborne gun cameras, range tracking and other hazardous environments. The companies and government agencies using these cameras are in need of replacing them with a more cost effective solution. Film-based cameras still produce the best resolving capability, however, film development time, chemical disposal, recurring media cost, and faster digital analysis are factors influencing the desire for a 16 mm film camera replacement. This paper will describe a new camera from Kodak that has been designed to replace 16 mm high speed film cameras.

  6. 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.

  7. 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.

  8. Digital Light Processing for high-brightness high-resolution applications

    NASA Astrophysics Data System (ADS)

    Hornbeck, Larry J.

    1997-05-01

    Electronic projection display technology for high-brightness applications had its origins in the Gretag Eidophor, an oil film-based projection system developed in the early 1940s. A number of solid state technologies have challenged the Eidophor, including CRT-addressed LCD light valves and active-matrix-addressed LCD panels. More recently, in response to various limitations of the LCD technologies, high-brightness systems have been developed based on Digital Light Processing technology. At the heart of the DLP projection display is the Digital Micromirror Device, a semiconductor-based array of fast, reflective digital light switches that precisely control a light source using a binary pulsewidth modulation technique. This paper describes the design, operation, performance, and advantages of DLP- based projection systems for high-brightness, high- resolution applications. It also presents the current status of high-brightness products that will soon be on the market.

  9. A highly sensitive and selective fluorescent Cu2+ sensor synthesized with silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Zheng, Jiannan; Xiao, Chuan; Fei, Qiang; Li, Ming; Wang, Baojun; Feng, Guodong; Yu, Hongmei; Huan, Yanfu; Song, Zhiguang

    2010-01-01

    A novel fluorescent nanosensor for the determination of Cu2+ was synthesized with N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QlOEt) grafted onto the surface of silica nanoparticles (SiNPs) using the reverse microemulsion method. Spherical SiNPs were used as substrate and QlOEt was used simultaneously as the binding and readout system for Cu2+. This sensor has been realized as a highly sensitive and selective technique for the detection and quantification of trace amounts of Cu2+. The probe exhibits a dynamic response range for Cu2+ from 2.0 × 10-6 to 2.0 × 10-5 M, with a detection limit of 3.8 × 10-7 M. Other alkali, alkaline earth, and transitional metal ions including Li+, K+, Mg2+, Ca2+, Sr2+, Mn2+, Zn2+, Mo6+, Pb2+, Ag+ had no significant interference on Cu2+ determination. Poisonous and flammable reagents are avoided during the synthesis of this nanosensor. Therefore the strategy explored in this work can be extended to the synthesis of other chemo- and biosensors for direct detection of specific targets in an intracellular environment.

  10. 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.

  11. Results from the LTX High-Speed Digital Holography System

    NASA Astrophysics Data System (ADS)

    Thomas, C. E. (Tommy), Jr.; Baylor, L. R.; Combs, S. K.; Meitner, S. J.; Rasmussen, D. A.; Granstedt, E. M.; Lundberg, D. P.; Jacobson, C. M.; Majeski, R.; Kaita, R.

    2011-10-01

    A high-speed CO2 laser digital holography system (500 frames per second (FPS) at 256 x 256 pixels, 1500 FPS at 128 x 128 pixels, etc., to a maximum of 43,000 FPS at 64 x 4 pixels) has been built for high-resolution imaging of electron density on the Lithium Tokamak Experiment (LTX). The laser operates at 9.1 microns by using an Oxygen-18 isotope, and has a power output up to 20 W. A FLIR SC4000 IR camera is used to capture the digital holograms. An acousto-optic modulator (AOM) is used to ``shutter'' the laser so that effective camera integration times down to less than one microsecond are possible. The system will be used for examining profile modifications on LTX with molecular cluster injection (MCI), supersonic gas injection (SGI), and external gas puffing. Results of measurements will be presented along with a discussion of system design, including noise-reduction techniques developed during system testing and initial operation. Partial Support from USDOE Contract DE-AC02-09CH11466 and USDOE Grant DE-FG02-07ER84724 is gratefully acknowledged.

  12. High-speed digital phonoscopy images analyzed by Nyquist plots

    NASA Astrophysics Data System (ADS)

    Yan, Yuling

    2012-02-01

    Vocal-fold vibration is a key dynamic event in voice production, and the vibratory characteristics of the vocal fold correlate closely with voice quality and health condition. Laryngeal imaging provides direct means to observe the vocal fold vibration; in the past, however, available modalities were either too slow or impractical to resolve the actual vocal fold vibrations. This limitation has now been overcome by high-speed digital imaging (HSDI) (or high-speed digital phonoscopy), which records images of the vibrating vocal folds at a rate of 2000 frames per second or higher- fast enough to resolve a specific, sustained phonatory vocal fold vibration. The subsequent image-based functional analysis of voice is essential to better understanding the mechanism underlying voice production, as well as assisting the clinical diagnosis of voice disorders. Our primary objective is to develop a comprehensive analytical platform for voice analysis using the HSDI recordings. So far, we have developed various analytical approaches for the HSDI-based voice analyses. These include Nyquist plots and associated analysese that are used along with FFT and Spectrogram in the analysis of the HSDI data representing normal voice and specific voice pathologies.

  13. Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices

    NASA Astrophysics Data System (ADS)

    Pavel, Alexandru Cezar

    The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that

  14. a Thz Photomixing Synthesizer Based on a Fiber Frequency Comb for High Resolution Rotational Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hindle, Francis; Mouret, Gael; Cuisset, Arnaud; Yang, Chun; Eliet, Sophie; Bocquet, Robin

    2010-06-01

    To date the principal application for photomixing sources has been for high resolution spectroscopy of gases due to the large tuning range and spectral purity. New Developments of the Opto-Electronic THz Spectrometer have been performed in order to obtain a powerful tool for High-Resolution Spectroscopy. The combination of two extended cavity laser diodes and fast charge carrier lifetime semiconductor materials has allowed a continuous-wave THz spectrometer to be constructed based on optical heterodyning. Unlike many THz sources, this instrument gives access to all frequencies in the range 0.3 to 3.5 THz with a resolution of 1 MHz. The main spectroscopic applications of this spectrometer were dedicated to line profile analysis of rotational transitions referenced in the spectroscopic databases. One limitation of the THz spectrometer was accuracy with which the generated frequency is known. Recently, this obstacle has been circled with the construction of a photomixing spectrometer where the two pump lasers are phase locked to two modes of a repetition rate stabilized frequency doubled fiber laser frequency comb. In order to achieve a tuning range in excess to 100 MHz a third cw laser was required in the new configuration of the THz spectrometer. To assess the performances of this instrument, the frequencies of the pure rotational transitions of OCS molecules have been measured between 0,8 to 1,2 THz. A rms inferior to 100 kHz, deduced from the frequencies measured, demonstrates that the THz photomixing synthesizer is now able to be competitive with microwave and submillimeter techniques. S. Matton, F. Rohart, R. Bocquet, D. Bigourd, A. Cuisset, F. Hindle, G. Mouret, J. Mol. Spectrosc., 2006, 239: 182. C. Yang, J. Buldyreva, I. E. Gordon, F. Rohart, A. Cuisset, G. Mouret, R. Bocquet, F. Hindle, J. Quant. Spectrosc. Radiat. Transfer, 2008, 109: 2857. G. Mouret, F. Hindle, A. Cuisset, C. Yang, R. Bocquet, M. Lours, D. Rovera, Opt. Express, 2009, 17: 22031.

  15. Bacteriorhodopsin as a high-resolution, high-capacity buffer for digital holographic measurements

    NASA Astrophysics Data System (ADS)

    Barnhart, D. H.; Koek, W. D.; Juchem, T.; Hampp, N.; Coupland, J. M.; Halliwell, N. A.

    2004-04-01

    Recent trends in optical metrology suggest that, in order for holographic measurement to become a widespread tool, it must be based on methods that do not require physical development of the hologram. While digital holography has been successfully demonstrated in recent years, unfortunately the limited information capacity of present electronic sensors, such as CCD arrays, is still many orders of magnitude away from directly competing with the high-resolution silver halide plates used in traditional holography. As a result, present digital holographic methods with current electronic sensors cannot record object sizes larger than several hundred microns at high resolution. In this paper, the authors report on the use of bacteriorhodopsin (BR) for digital holography to overcome these limitations. In particular, BR is a real-time recording medium with an information capacity (5000 line-pairs/mm) that even exceeds high resolution photographic film. As such, a centimetre-square area of BR film has the same information capacity of several hundred state-of-the-art CCD cameras. For digital holography, BR temporarily holds the hologram record so that its information content can be digitized for numeric reconstruction. In addition, this paper examines the use of BR for optical reconstruction without chemical development. When correctly managed, it is found that BR is highly effective, in terms of both quality and process time, for three-dimensional holographic measurements. Consequently, several key holographic applications, based on BR, are proposed in this paper.

  16. Highly precise measurement of HIV DNA by droplet digital PCR.

    PubMed

    Strain, Matthew C; Lada, Steven M; Luong, Tiffany; Rought, Steffney E; Gianella, Sara; Terry, Valeri H; Spina, Celsa A; Woelk, Christopher H; Richman, Douglas D

    2013-01-01

    Deoxyribonucleic acid (DNA) of the human immunodeficiency virus (HIV) provides the most sensitive measurement of residual infection in patients on effective combination antiretroviral therapy (cART). Droplet digital PCR (ddPCR) has recently been shown to provide highly accurate quantification of DNA copy number, but its application to quantification of HIV DNA, or other equally rare targets, has not been reported. This paper demonstrates and analyzes the application of ddPCR to measure the frequency of total HIV DNA (pol copies per million cells), and episomal 2-LTR (long terminal repeat) circles in cells isolated from infected patients. Analysis of over 300 clinical samples, including over 150 clinical samples assayed in triplicate by ddPCR and by real-time PCR (qPCR), demonstrates a significant increase in precision, with an average 5-fold decrease in the coefficient of variation of pol copy numbers and a >20-fold accuracy improvement for 2-LTR circles. Additional benefits of the ddPCR assay over qPCR include absolute quantification without reliance on an external standard and relative insensitivity to mismatches in primer and probe sequences. These features make digital PCR an attractive alternative for measurement of HIV DNA in clinical specimens. The improved sensitivity and precision of measurement of these rare events should facilitate measurements to characterize the latent HIV reservoir and interventions to eradicate it. PMID:23573183

  17. Highly Precise Measurement of HIV DNA by Droplet Digital PCR

    PubMed Central

    Strain, Matthew C.; Lada, Steven M.; Luong, Tiffany; Rought, Steffney E.; Gianella, Sara; Terry, Valeri H.; Spina, Celsa A.; Woelk, Christopher H.; Richman, Douglas D.

    2013-01-01

    Deoxyribonucleic acid (DNA) of the human immunodeficiency virus (HIV) provides the most sensitive measurement of residual infection in patients on effective combination antiretroviral therapy (cART). Droplet digital PCR (ddPCR) has recently been shown to provide highly accurate quantification of DNA copy number, but its application to quantification of HIV DNA, or other equally rare targets, has not been reported. This paper demonstrates and analyzes the application of ddPCR to measure the frequency of total HIV DNA (pol copies per million cells), and episomal 2-LTR (long terminal repeat) circles in cells isolated from infected patients. Analysis of over 300 clinical samples, including over 150 clinical samples assayed in triplicate by ddPCR and by real-time PCR (qPCR), demonstrates a significant increase in precision, with an average 5-fold decrease in the coefficient of variation of pol copy numbers and a >20-fold accuracy improvement for 2-LTR circles. Additional benefits of the ddPCR assay over qPCR include absolute quantification without reliance on an external standard and relative insensitivity to mismatches in primer and probe sequences. These features make digital PCR an attractive alternative for measurement of HIV DNA in clinical specimens. The improved sensitivity and precision of measurement of these rare events should facilitate measurements to characterize the latent HIV reservoir and interventions to eradicate it. PMID:23573183

  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. High aspect ratio CdS nanowires synthesized in microemulsion system

    SciTech Connect

    Fu Xun . E-mail: fuxun@qust.edu.cn; Wang Debao; Wang Jing; Shi Huaqiang; Song Caixia

    2004-10-04

    CdS nanowires with typical length more than 8 {mu}m and width of 30 nm on average have been successfully synthesized through Cd(NO{sub 3}){sub 2} reacting with CS{sub 2} and ethylenediamine in microemulsion system of sodium dodecylbenzene sulfonate (SBDS). The microstructures of the as-synthesized CdS nanowires were characterized using XRD, transmission electron microscopy (TEM) and HRTEM. The possible formation mechanism was discussed. The morphologies of CdS sample strongly depend on the concentration of surfactant in solutions.

  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 Speed Digital Holography for Density and Fluctuation Measurements

    SciTech Connect

    ThomasJr., C. E.; Baylor, Larry R; Combs, Stephen Kirk; Meitner, Steven J; Rasmussen, David A; Granstedt, E. M.; Majeski, R.; Kaita, R.

    2010-01-01

    The state of the art in electro-optics has advanced to the point where digital holographic acquisition of wavefronts is now possible. Holographic wavefront acquisition provides the phase of the wavefront at every measurement point. This can be done with accuracy on the order of a thousandth of a wavelength, given that there is sufficient care in the design of the system. At wave frequencies which are much greater than the plasma frequency, the plasma index of refraction is linearly proportional to the electron density and wavelength, and the measurement of the phase of a wavefront passing through the plasma gives the chord-integrated density directly for all points measured on the wavefront. High-speed infrared cameras up to 40 000 fps at 644 pixels with resolutions up to 640512 pixels suitable for use with a CO2 laser are readily available, if expensive.

  2. High speed digital holography for density and fluctuation measurements (invited)

    SciTech Connect

    Thomas, C. E. Jr.; Baylor, L. R.; Combs, S. K.; Meitner, S. J.; Rasmussen, D. A.; Granstedt, E. M.; Majeski, R. P.; Kaita, R.

    2010-10-15

    The state of the art in electro-optics has advanced to the point where digital holographic acquisition of wavefronts is now possible. Holographic wavefront acquisition provides the phase of the wavefront at every measurement point. This can be done with accuracy on the order of a thousandth of a wavelength, given that there is sufficient care in the design of the system. At wave frequencies which are much greater than the plasma frequency, the plasma index of refraction is linearly proportional to the electron density and wavelength, and the measurement of the phase of a wavefront passing through the plasma gives the chord-integrated density directly for all points measured on the wavefront. High-speed infrared cameras (up to {approx}40 000 fps at {approx}64x4 pixels) with resolutions up to 640x512 pixels suitable for use with a CO{sub 2} laser are readily available, if expensive.

  3. Dataflow computing approach in high-speed digital simulation

    NASA Technical Reports Server (NTRS)

    Ercegovac, M. D.; Karplus, W. J.

    1984-01-01

    New computational tools and methodologies for the digital simulation of continuous systems were explored. Programmability, and cost effective performance in multiprocessor organizations for real time simulation was investigated. Approach is based on functional style languages and data flow computing principles, which allow for the natural representation of parallelism in algorithms and provides a suitable basis for the design of cost effective high performance distributed systems. The objectives of this research are to: (1) perform comparative evaluation of several existing data flow languages and develop an experimental data flow language suitable for real time simulation using multiprocessor systems; (2) investigate the main issues that arise in the architecture and organization of data flow multiprocessors for real time simulation; and (3) develop and apply performance evaluation models in typical applications.

  4. HIGH SEQUENCE DIVERSITY IN THE RNA SYNTHESIZED AT THE LAMPBRUSH STAGE OF OÖGENESIS*

    PubMed Central

    Davidson, Eric H.; Hough, Barbara R.

    1969-01-01

    Many diverse RNA's are synthesized in the lampbrush stage oöcyte of Xenopus, as shown by the presence of different nucleotide sequences in the RNA population. This fact has been established by hybridizing lampbrush stage oöcyte RNA with an isolated nonrepetitive fraction of Xenopus DNA. Images PMID:5257126

  5. High sequence diversity in the RNA synthesized at the lampbrush stage of oögenesis.

    PubMed

    Davidson, E H; Hough, B R

    1969-06-01

    Many diverse RNA's are synthesized in the lampbrush stage oöcyte of Xenopus, as shown by the presence of different nucleotide sequences in the RNA population. This fact has been established by hybridizing lampbrush stage oöcyte RNA with an isolated nonrepetitive fraction of Xenopus DNA. PMID:5257126

  6. 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. PMID:27245962

  7. A reconstruction strategy to synthesize mesoporous SAPO molecular sieve single crystals with high MTO catalytic activity.

    PubMed

    Wang, Chan; Yang, Miao; Li, Mingrun; Xu, Shutao; Yang, Yue; Tian, Peng; Liu, Zhongmin

    2016-05-11

    Mesoporous SAPO-34 single crystals with tunable porosity and Si content have been fast synthesized within 4 hours by a reconstruction strategy, which show excellent hydrothermal stability and MTO catalytic activity. This new strategy is further proven to be applicable to prepare other mesoporous SAPO molecular sieve single crystals. PMID:27101359

  8. 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

    2014-10-01

    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. PMID:25131456

  9. 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.

  10. 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.

  11. Carbon: Eutectic Syntheses of Graphitic Carbon with High Pyrazinic Nitrogen Content (Adv. Mater. 6/2016).

    PubMed

    Fechler, Nina; Zussblatt, Niels P; Rothe, Regina; Schlögl, Robert; Willinger, Marc-Georg; Chmelka, Bradley F; Antonietti, Markus

    2016-02-01

    Starting from a powder mixture of ketones/urea, gentle heating results in liquefaction below the melting point of the respective components. The back-cover image shows a polarized optical microscopy image of a liquid-crystalline eutectic mixture in the supercooled liquidus, as discussed on page 1287 by N. Fechler and co-workers. This indicates the coupling of the monomers toward larger, preorganized assemblies. From this precursor system, "C2N" carbon is synthesized. PMID:26849666

  12. Design and implementation of high dynamic GNSS digital receiver

    NASA Astrophysics Data System (ADS)

    Li, Hanmei; Geng, Shengqun; Wang, Ce; Xu, Yong; Zhang, Qishan

    2007-11-01

    The paper presents a scheme of high dynamic GNSS digital receiver using FPGA xc4vsx55 of XILINX and DSP TMS320VC6701 of TI as core controller. Besides brief introduction of scheme design and hardware structure, the paper comprehensively introduces design and implementation of algorithms of fast acquisition and tracking of spread spectrum signal in high dynamic environment. Through optimized design, fast acquisition and tracking of both C code (coarse ranging code) and P code (precision ranging code) are realized in one chip of FPGA, under the control of DSP. Employing FFT-based fast acquisition algorithm, acquisition unit realizes the fast acquisition by duplicated using two FFT/IFFT units with time-sharing fashion, and other optimized FFT calculation structures. Carrier tracking loop is realized by adopting FLL+PLL method which using FLL tracking carrier Doppler shift with greater bandwidth making loop closed rapidly and using PLL precisely tracking carrier phase so as to achieve perfect tracking effects. PN code tracking loop is realized by using multiple non-coherent DLLs with various correlation spacing, which satisfying the requirements of larger tracking range as well as higher tracking precision by using broad spacing accomplishing initial tracking and narrow spacing realizing high precision tracking.

  13. 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.

  14. 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

  15. 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).

  16. 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.

  17. 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.

  18. Morphology of Si nanowires synthesized by high-temperature laser ablation

    NASA Astrophysics Data System (ADS)

    Tang, Y. H.; Zhang, Y. F.; Wang, N.; Lee, C. S.; Han, X. D.; Bello, I.; Lee, S. T.

    1999-06-01

    Silicon nanowires have been synthesized by laser ablation of Si powder targets at 1200 °C. Transmission electron microscopy study showed that most Si nanowires had smooth surfaces and nearly the same diameter of about 16 nm. Beside the most abundant smooth-surface nanowires, four other forms of nanowires, named spring-shaped, fishbone-shaped, frog-egg-shaped, and necklace-shaped nanowires, were observed. The formation of nanowires into different shapes was explained by the two-step growth model based on the vapor-liquid-solid mechanism.

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

    DOEpatents

    Demos, Stavros G.; Shverdin, Miroslav Y.; Shirk, Michael D.

    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.

  20. 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. PMID:27398502

  1. 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.

  2. 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.

  3. Performance of digital integrated circuit technologies at very high temperatures

    SciTech Connect

    Prince, J.L.; Draper, B.L.; Rapp, E.A.; Kromberg, J.N.; Fitch, L.T.

    1980-01-01

    Results of investigations of the performance and reliability of digital bipolar and CMOS integrated circuits over the 25 to 340/sup 0/C range are reported. Included in these results are both parametric variation information and analysis of the functional failure mechanisms. Although most of the work was done using commercially available circuits (TTL and CMOS) and test chips from commercially compatible processes, some results of experimental simulations of dielectrically isolated CMOS are also discussed. It was found that commercial Schottky clamped TTL, and dielectrically isolated, low power Schottky-clamped TTL, functioned to junction temperatures in excess of 325/sup 0/C. Standard gold doped TTL functioned only to 250/sup 0/C, while commercial, isolated I/sup 2/L functioned to the range 250/sup 0/C to 275/sup 0/C. Commercial junction isolated CMOS, buffered and unbuffered, functioned to the range 280/sup 0/C to 310/sup 0/C/sup +/, depending on the manufacturer. Experimental simulations of simple dielectrically isolated CMOS integrated circuits, fabricated with heavier doping levels than normal, functioned to temperatures in excess of 340/sup 0/C. High temperature life testing of experimental, silicone-encapsulated simple TTL and CMOS integrated circuits have shown no obvious life limiting problems to date. No barrier to reliable functionality of TTL bipolar or CMOS integrated ciruits at temperatures in excess of 300/sup 0/C has been found.

  4. 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.

  5. Automated analysis for microcalcifications in high resolution digital mammograms

    SciTech Connect

    Mascio, L.N.; Hernandez, J.M.; Logan, C.M.

    1994-10-01

    Digital mammography offers the promise of significant advances in early detection of breast cancer. Our overall goal is to design a digital system which improves upon every aspect of current mammography technology: the x-ray source, detector, visual presentation of the mammogram and computer-aided diagnosis capabilities. This paper will discuss one part of our whole-system approach -- the development of a computer algorithm using gray-scale morphology to automatically analyze and flag microcalcifications in digital mammograms in hopes of reducing the current percentage of false-negative diagnoses, which is estimated at 20%. The mamrnograms used for developing this ``mammographers assistant`` are film mammograms which we have digitized at either 70{mu}m or 35{mu}m per pixel resolution with 4096(12 bits) of gray level per pixel. For each potential microcalcification detected. in these images, we compute a number of features in order to distinguish between the different kinds of objects detected.

  6. Automated analysis for microcalcifications in high resolution digital mammograms

    SciTech Connect

    Mascio, L.N.; Hernandez, J.M.; Logan, C.M.

    1993-01-01

    Digital mammography offers the promise of significant advances in early detection of breast cancer. Our overall goal is to design a digital system which improves upon every aspect of current mammography technology: the x-ray source, detector, visual presentation of the mammogram and computer-aided diagnosis capabilities. This paper will discuss one part of our whole-system approach -- the development of a computer algorithm using gray-scale morphology to automatically analyze and flag microcalcifications in digital mammograms in hopes of reducing the current percentage of false-negative diagnoses, which is estimated at 20%. The mammograms used for developing this ``mammographers assistant`` are film mammograms which we have digitized at either 70 {mu}m or 35 {mu}m per pixel resolution with 4096 (12 bits) of gray level per pixel. For each potential microcalcification detected in these images, we compute a number of features in order to distinguish between the different kinds of objects detected.

  7. 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

  8. Phase transformations of high-purity PbI2 nanoparticles synthesized from lead-acid accumulator anodes

    NASA Astrophysics Data System (ADS)

    Malevu, T. D.; Ocaya, R. O.; Tshabalala, K. G.

    2016-09-01

    High-purity hexagonal lead iodide nanoparticles have been synthesized from a depleted sealed lead acid battery anode. The synthesized product was found to consist of the rare 6R polytype form of PbI2 that is thought to have good potential in photovoltaic applications. We investigate the effects of annealing time and post-melting temperature on the structure and optical properties using 1.5418 Å CuKα radiation. Photoluminescence measurements were done under 150 W/221 nm wavelength xenon excitation. Phase transformation was observed through XRD peaks when annealing time increased from 0.5-5 h. The nanoparticle grain size and inter-planar distance appeared to be independent of annealing time. PL measurements show three broad peaks in a range of 400 nm to 700 nm that are attributed to excitonic, donor-acceptor pair and luminescence bands from the deep levels.

  9. Size control, quantum confinement, and oxidation kinetics of silicon nanocrystals synthesized at a high rate by expanding thermal plasma

    SciTech Connect

    Han, Lihao E-mail: A.H.M.Smets@tudelft.nl; Zeman, Miro; Smets, Arno H. M. E-mail: A.H.M.Smets@tudelft.nl

    2015-05-25

    The growth mechanism of silicon nanocrystals (Si NCs) synthesized at a high rate by means of expanding thermal plasma chemical vapor deposition technique are studied in this letter. A bimodal Gaussian size distribution is revealed from the high-resolution transmission electron microscopy images, and routes to reduce the unwanted large Si NCs are discussed. Photoluminescence and Raman spectroscopies are employed to study the size-dependent quantum confinement effect, from which the average diameters of the small Si NCs are determined. The surface oxidation kinetics of Si NCs are studied using Fourier transform infrared spectroscopy and the importance of post-deposition passivation treatments of hydrogenated crystalline silicon surfaces are demonstrated.

  10. 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

  11. 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. PMID:24702934

  12. Ultra-high speed and low latency broadband digital video transport

    NASA Astrophysics Data System (ADS)

    Stufflebeam, Joseph L.; Remley, Dennis M.; Sullivan, Anthony; Gurrola, Hector

    2004-07-01

    Various approaches for transporting digital video over Ethernet and SONET networks are presented. Commercial analog and digital frame grabbers are utilized, as well as software running under Microsoft Windows 2000/XP. No other specialized hardware is required. A network configuration using independent VLANs for video channels provides efficient transport for high bandwidth data. A framework is described for implementing both uncompressed and compressed streaming with standard and non-standard video. NTSC video is handled as well as other formats that include high resolution CMOS, high bit-depth infrared, and high frame rate parallel digital. End-to-end latencies of less than 200 msec are achieved.

  13. High-resolution digital profiling of the epigenome.

    PubMed

    Zentner, Gabriel E; Henikoff, Steven

    2014-12-01

    The widespread adoption of short-read DNA sequencing as a digital epigenomic readout platform has motivated the development of genome-wide tools that achieve base-pair resolution. New methods for footprinting and affinity purification of nucleosomes, RNA polymerases, chromatin remodellers and transcription factors have increased the resolution of epigenomic profiling by two orders of magnitude, leading to new insights into how the chromatin landscape affects gene regulation. These digital epigenomic tools have also been applied to directly profile both turnover kinetics and transcription in situ. In this Review, we describe how these new genome-wide tools allow interrogation of diverse aspects of the epigenome. PMID:25297728

  14. Optically assisted high-speed, high resolution analog-to-digital conversion (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Zmuda, Henry; Hanna, Shane; Bussjager, R. J.; Fanto, M. L.; Hayduk, M. J.; Johns, S. T.; Malowicki, J. E.; Repak, P. L.

    2005-05-01

    An approach that modifies an analog fiber optic link with a recirculating optical loop as a means to realize a high-speed, high-resolution Analog-to-Digital Converted (ADC) is presented. The loops stores a time-limited microwave signal so that it may be digitized by using a slower, conventional electronic ADC. Detailed analytical analysis of the dynamic range and noise figure shows that under appropriate conditions the microwave signal degradation is sufficiently small so as to allow the digitization of a multi-gigahertz signal with a resolution greater than 10 effective bits. Experimental data is presented which shows that a periodic extension of the input signal can be sustained for well over one hundred periods that in turn suggests an electronic ADC speed-up factor of over 100. The data also shows that polarization effects must be carefully managed to inhibit the loops tendency to lase even though the loop itself contains no frequency-selective elements.

  15. 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…

  16. Environmentally Friendly Mechanochemical Syntheses and Conversions of Highly Luminescent Cu(I) Dinuclear Complexes.

    PubMed

    Kobayashi, Atsushi; Hasegawa, Tatsuya; Yoshida, Masaki; Kato, Masako

    2016-03-01

    Luminescent dinuclear Cu(I) complexes, [Cu2X2(dpypp)2] [Cu-X; X = Cl, Br, I; dpypp = 2,2'-(phenylphosphinediyl)dipyridine], were successfully synthesized by a solvent-assisted mechanochemical method. A trace amount of the assisting solvent plays a key role in the mechanochemical synthesis; only two solvents possessing the nitrile group, CH3CN and PhCN, were effective for promoting the formation of dinuclear Cu-X. X-ray analysis revealed that the dinuclear structure with no Cu···Cu interactions, bridged by two dpypp ligands, was commonly formed in all Cu-X species. These complexes exhibited bright green emission in the solid state at room temperature (Φ = 0.23, 0.50, and 0.74; λem = 528, 518, and 530 nm for Cu-Cl, Cu-Br, and Cu-I, respectively). Emission decay measurement and TD-DFT calculation suggested that the luminescence of Cu-X could be assigned to phosphorescence from the triplet metal-to-ligand charge-transfer ((3)MLCT) excited state, effectively mixed with the halide-to-ligand charge-transfer ((3)XLCT) excited state, at 77 K. The source of emission changed to thermally activated delayed fluorescence (TADF) with the same electronic transition nature at room temperature. In addition, the CH3CN-bound analogue, [Cu2(CH3CN)2(dpypp)2](BF4)2, was successfully mechanochemically converted to Cu-X by grinding with solid KX in the presence of a trace amount of assisting water. PMID:26866384

  17. Reversible compression techniques for high-resolution digital teleradiology

    NASA Astrophysics Data System (ADS)

    Kuduvalli, Gopinath R.; Rangayyan, Rangaraj M.

    1990-06-01

    The sheer amount of data involved in the fields of Picture Archival and Communication systems (PACS) and Teleradiology has created a growing interest in efficient compression of medical images. Diagnostic quality digitization of typical medical images such as chest x-rays and mammograms requires about 4Kx4K pixels digitized to 10 or 12 bits. In most medical applications any loss of quality in compression and decompression of images cannot be tolerated. We are investigating coding techniques for reversible compression of medical images in the above context. In this paper we present the results of application of adaptive linear predictive coding techniques to a few typical medical images digitized to about 4Kx4Kxl2-bits using an Eikonix 1412 camera. It was seen that about 75 reduction in transmission times is possible without any loss of image quality for the images considered. It was observed that the optimal predictor order and the optimal block size for adaptive linear predictive coding are higher compared to those for the same images digitized to lower spatial resolution. 1.

  18. Root-Raised Cosine Filter Implementation That Uses Canonical Signed Digits for High-Speed Digital Filter Applications

    NASA Technical Reports Server (NTRS)

    Kim, Heechul

    1997-01-01

    NASA Lewis Research Center's Space Communications Division has been investigating high-speed digital filters that can operate at a higher speed than those in current use for a digital modulator and demodulator (modem). Using the Canonical Signed Digits (CSD) number representation for filter coefficients is a very effective way to increase the filter's speed while reducing complexity in the digital filter hardware design. This approach is a good alternative to using an expensive parallel-processing design technique or custom, application-specific integrated circuits. Such integrated circuits may not be suitable for applications that require filter speeds faster than what application-specific integrated circuits digital signal processors can offer for a dedicated channel. When a communication channel is a dedicated, multiplication process--a costly, time-consuming process--it can be greatly simplified by a replacement of the filter coefficients with CSD numbers. A computer code written with the MATLAB software package runs the program and generates CSD-represented filter coefficients that are based on minimizing minimum mean square errors. Also, the Alta Group of Cadence's Signal Processing Workstation is used to simulate and analyze the CSD filter responses. The impulse response of the root-raised cosine filter that is used as a base model is defined. From this filter, a set of coefficients is sampled and stored in a file. For the all coefficients, the optimal CSD number for each coefficient is searched on the basis of the minimum-mean-square-errors criterion. Because the distribution of CSD numbers is not uniform, quantization errors tend to be bigger for coefficients greater than 1/2. To offset errors that occur in a region of coefficients between 1/2 to 1 and to better represent fractions with CSD numbers, an extra nonzero digit is allowed for any coefficients exceeding 1/2. This will greatly improve frequency response as well as intersymbol interference at the

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. High-resolution digital readout for uncooled smart IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ringh, Ulf; Jansson, Christer; Liddiard, Kevin C.; Reinhold, Olaf

    1997-11-01

    This paper discusses the development of a high resolution digital readout from a 2D array of uncooled IR detectors. The need for a high resolution analogue to digital converter (ADC) is described and anew concept is presented. Experimental VLSI arrays have been designed using 0.8 micrometers CMOS technology and the pixel size is 40 micrometers X 40 micrometers . The concept has been demonstrated by using 320 parallel 16 bit ADCs in a 320 X 240 readout array with a frame rate of 30 Hz. High linearity and low noise is obtained and the power consumption for each ADC is 0.5 mW. The high digital resolution allows for digital offset correction off the local plane. A 16 X 16 version of the readout circuit has been postprocessed with uncooled IR detectors. These are currently under evaluation.

  5. 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

  6. One-pot synthesized hierarchical zeolite supported metal nanoparticles for highly efficient biomass conversion.

    PubMed

    Wang, Darui; Ma, Bing; Wang, Bo; Zhao, Chen; Wu, Peng

    2015-10-21

    Hierarchically porous zeolite supported metal nanoparticles are successfully prepared through a base-assisted chemoselective interaction between the silicon species on the zeolite crystal surface and metal salts, in which in situ construction of mesopores and high dispersion of metal species are realized simultaneously. PMID:26361087

  7. Boron nitrides synthesized directly from the elements at high pressures and temperatures

    SciTech Connect

    Nicol, M.; Yoo, C.S.; Akella, J.; Cynn, H.

    1996-11-01

    We use angle-resolved synchrotron x-ray diffraction, laser sample heating, and diamond-anvil cells to follow in-situ chemical reactions directly between elemental boron and nitrogen. The structures of the solid reaction products vary with pressure. Below 10 GPa, hexagonal BN is the product; cubic or wurzite BN form at higher pressures. Under nitrogen-rich conditions, another hexagonal allotrope occurs which seems to be a new highly transparent, low density h`-BN. No direct reactions occur at ambient temperature even at pressures as high as 50 GPa, implying that a large activation barrier limits the kinetics of these exothermic processes. Laser heating overcomes the large kinetic activation barrier and initiates spontaneous, self-sustaining exothermic reactions even at moderate pressures.

  8. with very high saturation magnetization and negligible dielectric loss synthesized via a soft chemical route

    NASA Astrophysics Data System (ADS)

    Mukherjee, S.; Pradip, S.; Mishra, A. K.; Das, D.

    2014-07-01

    Materials with high saturation magnetization and low dielectric loss are in great demand due to the great boom in communication industry. In this paper, we report the synthesis of nanoferrites with the generic formula Zn x Ni(1- x)Fe2O4 ( x = 0.0, 0.1, 0.3 and 0.5) through chemical co-precipitation technique. The sample with x = 0.5 showed a saturation magnetization of 8.2 μ B which is the highest reported for any ferrite. Coupled to this excellent magnetic property, this ferrite has shown a negligible dielectric loss tangent over a large frequency window from 100 Hz to 1 MHz. The high values of saturation magnetization have been attributed to the composite effect of large-scale cationic migration and surface spin disorder.

  9. 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…

  10. 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

  11. 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. PMID:25500856

  12. Microintaglio Printing of In situ Synthesized Proteins Enables Rapid Printing of High-Density Protein Microarrays Directly from DNA Microarrays

    NASA Astrophysics Data System (ADS)

    Biyani, Manish; Moriyasu, Junpei; Tanaka, Yoko; Sato, Shusuke; Ueno, Shingo; Ichiki, Takanori

    2013-08-01

    A simple and versatile approach to the simultaneous on-chip synthesis and printing of proteins has been studied for high-density protein microarray applications. The method used is based on the principle of intaglio printing using microengraved plates. Unlike conventional approaches that require multistep reactions for synthesizing proteins off the chip followed by printing using a robotic spotter, our approach demonstrates the following: (i) parallel and spotter-free printing of high-density protein microarrays directly from a type of DNA microarray and (ii) microcompartmentalization of cell-free coupled transcription/translation reaction and direct transferring of picoliter protein solution per spot to pattern microarrays of 25-100 µm features.

  13. New co-spray way to synthesize high quality ZnS films

    NASA Astrophysics Data System (ADS)

    Bouznit, Y.; Beggah, Y.; Boukerika, A.; Lahreche, A.; Ynineb, F.

    2013-11-01

    In the present study, we report for the first time the synthesis of ZnS films using co-spray method, in which the reactants were mixed in the vapor state contrary to that seen in previous spray configurations. In order to obtain the optimum conditions for growing high quality ZnS thin films related to this approach, a series of samples with different Zn:S atomic ratios were investigated. X-ray diffraction (XRD) analysis indicated that both solid state and phase formation were strongly dependent on Zn:S atomic ratio. In the absence of sulfur element, pure ZnO phase showing hexagonal wurtzite structure with (0 0 2) preferential orientation was obtained. When one eighth of sulfur was implicated, the (0 0 2) diffraction peak of ZnO was broadened and displaced toward lower angles. Once one quarter of sulfur was involved, no discernible diffraction peaks could be seen. Films deposited using solutions with Zn:S ratio of 1:1/2, 1:1 and 1:2 have pure ZnS phase showing hexagonal wurtzite structure with a strong preferential orientation. Near stoichiometric ZnS films were achieved with Zn:S atomic ratio close to 1:1. All films have high transmittance of about 80% in the visible region.

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

    PubMed

    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

  15. 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.

  16. 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.

  17. 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.

  18. Pulicaria glutinosa extract: a toolbox to synthesize highly reduced graphene oxide-silver nanocomposites.

    PubMed

    Al-Marri, Abdulhadi H; Khan, Mujeeb; Khan, Merajuddin; Adil, Syed F; Al-Warthan, Abdulrahman; Alkhathlan, Hamad Z; Tremel, Wolfgang; Labis, Joselito P; Siddiqui, Mohammed Rafiq H; Tahir, Muhammad N

    2015-01-01

    A green, one-step approach for the preparation of graphene/Ag nanocomposites (PE-HRG-Ag) via simultaneous reduction of both graphene oxide (GRO) and silver ions using Pulicaria glutinosa plant extract (PE) as reducing agent is reported. The plant extract functionalizes the surfaces of highly reduced graphene oxide (HRG) which helps in conjugating the Ag NPs to HRG. Increasing amounts of Ag precursor enhanced the density of Ag nanoparticles (NPs) on HRG. The preparation of PE-HRG-Ag nanocomposite is monitored by using ultraviolet-visible (UV-Vis) spectroscopy, powder X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The as-prepared PE-HRG-Ag nanocomposities display excellent surface-enhanced Raman scattering (SERS) activity, and significantly increased the intensities of the Raman signal of graphene. PMID:25569090

  19. Design of a high performance CMOS charge pump for phase-locked loop synthesizers

    NASA Astrophysics Data System (ADS)

    Zhiqun, Li; Shuangshuang, Zheng; Ningbing, Hou

    2011-07-01

    A new high performance charge pump circuit is designed and realized in 0.18 μm CMOS process. A wide input ranged rail-to-rail operational amplifier and self-biasing cascode current mirror are used to enable the charge pump current to be well matched in a wide output voltage range. Furthermore, a method of adding a precharging current source is proposed to increase the initial charge current, which will speed up the settling time of CPPLLs. Test results show that the current mismatching can be less than 0.4% in the output voltage range of 0.4 to 1.7 V, with a charge pump current of 100 μA and a precharging current of 70 μA. The average power consumption of the charge pump in the locked condition is around 0.9 mW under a 1.8 V supply voltage.

  20. Pulicaria glutinosa Extract: A Toolbox to Synthesize Highly Reduced Graphene Oxide-Silver Nanocomposites

    PubMed Central

    Al-Marri, Abdulhadi H.; Khan, Mujeeb; Khan, Merajuddin; Adil, Syed F.; Al-Warthan, Abdulrahman; Alkhathlan, Hamad Z.; Tremel, Wolfgang; Labis, Joselito P.; Siddiqui, Mohammed Rafiq H.; Tahir, Muhammad N.

    2015-01-01

    A green, one-step approach for the preparation of graphene/Ag nanocomposites (PE-HRG-Ag) via simultaneous reduction of both graphene oxide (GRO) and silver ions using Pulicaria glutinosa plant extract (PE) as reducing agent is reported. The plant extract functionalizes the surfaces of highly reduced graphene oxide (HRG) which helps in conjugating the Ag NPs to HRG. Increasing amounts of Ag precursor enhanced the density of Ag nanoparticles (NPs) on HRG. The preparation of PE-HRG-Ag nanocomposite is monitored by using ultraviolet–visible (UV-Vis) spectroscopy, powder X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The as-prepared PE-HRG-Ag nanocomposities display excellent surface-enhanced Raman scattering (SERS) activity, and significantly increased the intensities of the Raman signal of graphene. PMID:25569090

  1. MerMade: An Oligodeoxyribonucleotide Synthesizer for High Throughput Oligonucleotide Production in Dual 96-Well Plates

    PubMed Central

    Rayner, Simon; Brignac, Stafford; Bumeister, Ron; Belosludtsev, Yuri; Ward, Travis; Grant, O’dell; O’Brien, Kevin; Evans, Glen A.; Garner, Harold R.

    1998-01-01

    We have designed and constructed a machine that synthesizes two standard 96-well plates of oligonucleotides in a single run using standard phosphoramidite chemistry. The machine is capable of making a combination of standard, degenerate, or modified oligos in a single plate. The run time is typically 17 hr for two plates of 20-mers and a reaction scale of 40 nm. The reaction vessel is a standard polypropylene 96-well plate with a hole drilled in the bottom of each well. The two plates are placed in separate vacuum chucks and mounted on an xy table. Each well in turn is positioned under the appropriate reagent injection line and the reagent is injected by switching a dedicated valve. All aspects of machine operation are controlled by a Macintosh computer, which also guides the user through the startup and shutdown procedures, provides a continuous update on the status of the run, and facilitates a number of service procedures that need to be carried out periodically. Over 25,000 oligos have been synthesized for use in dye terminator sequencing reactions, polymerase chain reactions (PCRs), hybridization, and RT–PCR. Oligos up to 100 bases in length have been made with a coupling efficiency in excess of 99%. These machines, working in conjunction with our oligo prediction code are particularly well suited to application in automated high throughput genomic sequencing. PMID:9685322

  2. 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.

  3. Shoreline Change Monitoring Using High Resolution Digital Photogrammetric Technique

    NASA Astrophysics Data System (ADS)

    Ahn, Y.; Lee, H.; Kim, K. H.; Shin, B. S.; Huh, K. I.

    2015-12-01

    Shoreline change has been measured with conventional surveying techniques such as Total station, GNSS, EDM etc. These measurements provide short/long term variation of nearshore evolution which enables us to estimate erosional and accretion sediment volume of the beach. This observation of ocean morphology currently has been utilized through the advance of optical imaging system and related digital image analysis. When deployed with proper viewing geometry, ground based digital imaging system can provide higher spatial/temporal resolution of shoreline change than satellite remote sensing data. In this study, we focus on generating time series of shore line change in Gwangan/Songjung beach in Busan, Korea where two DSLR imaging station have been successfully installed nearly at the end of each beach span. Via single photo photogrammetric techniques such as lens calibration, interior/exterior orientation, feature tracking, projection toward water surface, we aim to 1) calibrate out time lapse camera system, 2) verify with conventionally observed shorelines and finally 3) quantify the trend of ocean morphology in target sites.

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

    DOE PAGESBeta

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; Steren, Carlos A.; Goodwin, Andrew; Coughlin, E. Bryan; Gido, Samuel; Beiner, Mario; Hong, Kunlun; Kang, Nam -Goo; et al

    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-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).

  6. 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. PMID:19044710

  7. 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.

  8. Cholesterol and steroid synthesizing smooth endoplasmic reticulum of adrenocortical cells contains high levels of translocation apparatus proteins.

    PubMed

    Black, V H; Sanjay, A; van Leyen, K; Möeller, I; Lauring, B; Kreibich, G

    2002-11-01

    Steroid-secreting cells possess abundant smooth endoplasmic reticulum whose membranes contain many enzymes involved in sterol and steroid synthesis. In this study we demonstrate that adrenal smooth microsomal subfractions enriched in these membranes also possess high levels of proteins belonging to the translocation apparatus, proteins previously assumed to be confined to morphologically identifiable rough endoplasmic reticulum (RER). We further demonstrate that these smooth microsomal subfractions are capable of effecting the functions of these protein complexes: co-translational translocation, signal peptide cleavage and N-glycosylation of newly synthesized polypeptides. We hypothesize that these elements participate in regulating the levels of ER-targeted membrane proteins involved in cholesterol and steroid metabolism in a sterol-dependent and hormonally-regulated manner. PMID:12530645

  9. 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.

  10. Optimizing CMYK mapping for high speed digital inkjet webpress

    NASA Astrophysics Data System (ADS)

    Zeng, Ruzhu; Zeng, Huanzhao

    2013-02-01

    The CMYK to CMYK mapping preserving the black channel is a method to solve the problem in standard ICC color management that lacks the capability of preserving the K channel for printing CMYK contents. While the method has been successfully used for digital commercial printing, limitations and areas for improvement are found. To address these problems in generating CMYK re-rendering tables, an alternative method is developed. The K usage and total ink usage are optimized in a color separation step. Instead of preserving the K channel globally, it preserves K-only gray contents and maps other colors by optimizing the print quality and ink usage. Experiments verify that the method significantly improves the print quality.

  11. Advanced signaling technologies for high-speed digital fiber-optic links.

    PubMed

    Stark, Andrew J; Isautier, Pierre; Pan, Jie; Pavan, Sriharsha Kota; Filer, Mark; Tibuleac, Sorin; Lingle, Robert; de Salvo, Richard; Ralph, Stephen E

    2014-09-01

    We summarize the most recent research of the Georgia Tech Terabit Optical Networking Consortium and the state-of-the-art in fiber telecommunications. These results comprise high-capacity single-mode fiber systems with digital coherent receivers and shorter-reach multimode fiber links with vertical cavity surface emitting lasers. We strongly emphasize the capabilities that sophisticated digital signal processing and electronics add to these fiber-based data transport links. PMID:25321383

  12. Self-mixing digital closed-loop vibrometer for high accuracy vibration measurements

    NASA Astrophysics Data System (ADS)

    Magnani, Alessandro; Melchionni, Dario; Pesatori, Alessandro; Norgia, Michele

    2016-04-01

    The novelty of Self-mixing interferometry is represented by the combination of high accuracy and contactless operation with compact, very-low-cost and user-friendly setup. This paper introduces state of the art techniques to monitor vibrations focusing on a novel digital feedback vibrometer. It exploits a control loop to delete interferometric signal distortion and improve measurement accuracy. A digital implementation is proposed to enhance system performances through a real-time elaboration.

  13. High-pressure, high-temperature syntheses in the B-C-N-O system. I. Preparation and characterization

    SciTech Connect

    Hubert, H.; Petuskey, W.T.; McMillan, P.F.

    1997-11-01

    We synthesized several {alpha}-rhombohedral B-rich materials belonging to the B-C-N-O system using a multianvil press, B-C-O materials were prepared by reacting mixtures of B, C, and B{sub 2}O{sub 3} in the 5 to 7.5 GPa pressure range and at a temperature of 1700{degrees}C. Powder X-ray diffraction and parallel electron energy-loss spectroscopy with a transmission electron microscope showed that the B{sub x}C{sub y}O{sub z} phases obtained are based on the {alpha}-rhombohedral B structure. Crystals of composition B{sub 6}C{sub 1.1}O{sub 0.33} to B{sub 6}C{sub 1.28}O{sub 0.31} ranging in size from 1 to 20 {mu}m were grown. Small transparent lustrous red cleavage flakes were obtained for stoichiometries close to B{sub 6}O. The growth of boron carbide nanorods was also observed in some of the run products. We report the first conclusive bulk synthesis of a new boron nitride, B{sub 6}N{sub 1-x}, obtained by reacting B and hexagonal BN at 7.5 Gpa and 1700{degrees}C. The structure of this compound is derived from that of {alpha}-rhombohedral B (space group R{bar 3}m) and the refined hexagonal cell parameters are a{sub h} = 5.457 {angstrom} and c{sub h} = 12.241 {angstrom}.

  14. Highly visible light active Ag@TiO2 nanocomposites synthesized using an electrochemically active biofilm: a novel biogenic approach

    NASA Astrophysics Data System (ADS)

    Khan, M. Mansoob; Ansari, Sajid A.; Amal, M. Ikhlasul; Lee, Jintae; Cho, Moo Hwan

    2013-05-01

    Titanium dioxide (TiO2) nanoparticles were decorated with different amounts of silver nanoparticles (AgNPs) using an electrochemically active biofilm (EAB), which is a biogenic approach that leads to the formation of Ag@TiO2 nanocomposites. UV-vis spectroscopy, photoluminescence, X-ray diffraction and electron microscopy showed AgNPs, 2-5 nm in size, well-dispersed and anchored to the TiO2 surface and overall synthesis of Ag@TiO2 nanocomposites. The photocatalytic performance of the as-synthesized Ag@TiO2 nanocomposites was evaluated in terms of their efficiency for the photodecomposition of methylene blue (MB) in an aqueous solution under visible light irradiation. The nanocomposites showed exceptionally high photodecomposition efficiency (>7 times) compared to commercial TiO2 (Sigma). The enhanced photocatalytic activity was attributed to the synergistic contribution of both a delayed charge recombination rate caused by the high electronic mobility of the AgNPs and the increased surface area originating from the nanometer sized AgNPs on TiO2. The nanocomposites also showed exceptionally high stability and reusability under similar experimental conditions.Titanium dioxide (TiO2) nanoparticles were decorated with different amounts of silver nanoparticles (AgNPs) using an electrochemically active biofilm (EAB), which is a biogenic approach that leads to the formation of Ag@TiO2 nanocomposites. UV-vis spectroscopy, photoluminescence, X-ray diffraction and electron microscopy showed AgNPs, 2-5 nm in size, well-dispersed and anchored to the TiO2 surface and overall synthesis of Ag@TiO2 nanocomposites. The photocatalytic performance of the as-synthesized Ag@TiO2 nanocomposites was evaluated in terms of their efficiency for the photodecomposition of methylene blue (MB) in an aqueous solution under visible light irradiation. The nanocomposites showed exceptionally high photodecomposition efficiency (>7 times) compared to commercial TiO2 (Sigma). The enhanced

  15. The TDPAC study of the hyperfine interactions at 111Cd nuclei in RAl 3 compounds synthesized under high pressure

    NASA Astrophysics Data System (ADS)

    Tsvyashchenko, A. V.; Fomicheva, L. N.; Brudanin, V. B.; Kochetov, O. I.; Salamatin, A. V.; Velichkov, A.; Wiertel, M.; Budzynski, M.; Sorokin, A. A.; Ryasny, G. K.; Komissarova, B. A.

    2007-06-01

    The time-differential perturbed angular correlations technique (TDPAC) has been employed for measuring the parameters of hyperfine interactions in earlier known RAl 3 compounds, synthesized at high pressure (8 GPa) and high temperature, where R = La, Ce, Sm, Gd, Tb, Dy, Ho, Er, Yb and Lu. The 111Cd( 111In) radioactive atom was used as a probe nucleus. The X-ray method has revealed that with the increase in the atomic number of a rare-earth element R, the obtained RAl 3 high-pressure phases crystallize, respectively, into orthorhombic, hexagonal and cubic structures. It has been found that in the compounds containing R=La, Ce, Sm and Gd, a deviation from earlier known structural types and the formation of new ones is observed, which is associated with the change of the stoichiometric composition of the said compounds. The results of the PAC measurements have confirmed the deviation from the predetermined stoichiometric composition 1R:3Al for the compounds LaAl 3, CeAl 3, SmAl 3 and GdAl 3 and have verified the RAl 3 stoichiometric structure for the other high-pressure phases obtained in this work.

  16. Three-dimensional digital holographic aperture synthesis for rapid and highly-accurate large-volume metrology

    NASA Astrophysics Data System (ADS)

    Crouch, Stephen; Kaylor, Brant M.; Barber, Zeb W.; Reibel, Randy R.

    2015-09-01

    Currently large volume, high accuracy three-dimensional (3D) metrology is dominated by laser trackers, which typically utilize a laser scanner and cooperative reflector to estimate points on a given surface. The dependency upon the placement of cooperative targets dramatically inhibits the speed at which metrology can be conducted. To increase speed, laser scanners or structured illumination systems can be used directly on the surface of interest. Both approaches are restricted in their axial and lateral resolution at longer stand-off distances due to the diffraction limit of the optics used. Holographic aperture ladar (HAL) and synthetic aperture ladar (SAL) can enhance the lateral resolution of an imaging system by synthesizing much larger apertures by digitally combining measurements from multiple smaller apertures. Both of these approaches only produce two-dimensional imagery and are therefore not suitable for large volume 3D metrology. We combined the SAL and HAL approaches to create a swept frequency digital holographic 3D imaging system that provides rapid measurement speed for surface coverage with unprecedented axial and lateral resolution at longer standoff ranges. The technique yields a "data cube" of Fourier domain data, which can be processed with a 3D Fourier transform to reveal a 3D estimate of the surface. In this paper, we provide the theoretical background for the technique and show experimental results based on an ultra-wideband frequency modulated continuous wave (FMCW) chirped heterodyne ranging system showing ~100 micron lateral and axial precisions at >2 m standoff distances.

  17. 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

  18. Self-Digitization of Samples into a High-Density Microfluidic Bottom-Well Array

    PubMed Central

    Schneider, Thomas; Yen, Gloria S.; Thompson, Alison M.; Burnham, Daniel R.; Chiu, Daniel T.

    2013-01-01

    This paper describes a sample digitization method that generates tens of thousands of nanoliter-sized droplets in a high-density array in a matter of minutes. We show that the sample digitization depends on both the geometric design of the microfluidic device and the viscoelastic forces between the aqueous sample and a continuous oil phase. Our design avoids sample loss: Samples are split into tens of thousands of discreet volumes with close to 100% efficiency without the need for any expensive valving or pumping systems. We envision this technology will have broad applications that require simple sample digitization within minutes, such as digital polymerase chain reactions and single-cell studies. PMID:24099270

  19. High-definition hematoxylin and eosin staining in a transition to digital pathology

    PubMed Central

    Martina, Jamie D.; Simmons, Christopher; Jukic, Drazen M.

    2011-01-01

    Introduction: A lot of attention has been generated in recent years by digital pathology and telepathology. Multiple reasons for and barriers to effective adoption are discussed in the current literature. Digital slides are the most promising medium at this time. The goal of our study was to evaluate whether the change in the methodology, particularly utilizing the so-called high-definition hematoxylin and eosin (H and E) slides, enhanced the quality of the final digital slide, and whether pathologists who tested the results perceived this as a difference in quality. Methods: The study was a blinded comparison of digital slides prepared using two methods: standard H&E batch staining and automated individual “high definition” HD HE staining. Four pathologists have compared 80 cases stained with each method. Results: The results discussed in this study show potential promise that the utilization of protocol(s) adapted for tissue and for imaging might be preferable for digital pathology in at least some of the pathology subspecialties. In particular, the protocol evaluated here was capable of turning out digital slides that had more contrast and detail, and therefore were perceived to provide enhanced diagnostically significant information for the pathologist. PMID:22059146

  20. Design and application of a digital array high-speed camera system

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Yao, Xuefeng; Ma, Yinji; Yuan, Yanan

    2016-03-01

    In this paper, a digital array high-speed camera system is designed and applied in dynamic fracture experiment. First, the design scheme for 3*3 array digital high-speed camera system is presented, including 3*3 array light emitting diode (LED) light source unit, 3*3 array charge coupled device (CCD) camera unit, timing delay control unit, optical imaging unit and impact loading unit. Second, the influence of geometric optical parameters on optical parallax is analyzed based on the geometric optical imaging mechanism. Finally, combining the method of dynamic caustics with the digital high-speed camera system, the dynamic fracture behavior of crack initiation and propagation in PMMA specimen under low-speed impact is investigated to verify the feasibility of the high-speed camera system.

  1. 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

  2. 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

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

    PubMed

    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. 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.

  5. 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

  6. Mathematics Achievement with Digital Game-Based Learning in High School Algebra 1 Classes

    ERIC Educational Resources Information Center

    Ferguson, Terri Lynn Kurley

    2014-01-01

    This study examined the impact of digital game-based learning (DGBL) on mathematics achievement in a rural high school setting in North Carolina. A causal comparative research design was used in this study to collect data to determine the effectiveness of DGBL in high school Algebra 1 classes. Data were collected from the North Carolina…

  7. Development of the Digital High School Project: A School-University Partnership

    ERIC Educational Resources Information Center

    Savenye, Wilhelmina; Dwyer, Herb; Niemczyk, Mary; Olina, Zane; Kim, Alexander; Nicolaou, Adamos; Kopp, Howard

    2003-01-01

    A school district in the southwestern United States has over the past several years built its infrastructure to support high-quality technology integration by its teachers. The district partnered with a nearby university's educational technology graduate program to develop a digital high school project. Teachers and advanced instructional-design…

  8. 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…

  9. 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.

  10. A simple strategy for synthesizing highly luminescent carbon nanodots and application as effective down-shifting layers.

    PubMed

    Han, Xugen; Zhong, Sihua; Pan, Wei; Shen, Wenzhong

    2015-02-13

    We propose a novel strategy to prepare highly luminescent carbon nanodots (C-dots) by employing a hydrothermal method with citric acid as the carbon source and ethylenediamine as the nitrogen source, together with adding moderate ammonia water (AW) to achieve both appropriate inner structure and excellent N passivation. The effect of pH value and AW amount on the luminescence properties has been thoroughly investigated. The photoluminescence quantum yield of the resultant C-dots reaches as high as 84.8%, which is of 10.56% higher than that of the C-dots synthesized in the absence of AW in the reaction precursors. We have further combined the highest luminescent C-dots with polyvinyl alcohol to form luminescent down-shifting layers on silicon nanowire solar cells. An effective enhancement of short-circuit current density has been realized and the contribution of the down-shifting has been extracted quantitatively from the deterioration of surface reflectance and the gain of the optical absorption redistribution by means of a theoretical model on external quantum efficiency analysis. PMID:25611852

  11. Characterization of a Novel Fructosyltransferase from Lactobacillus reuteri That Synthesizes High-Molecular-Weight Inulin and Inulin Oligosaccharides

    PubMed Central

    van Hijum, S. A. F. T.; van Geel-Schutten, G. H.; Rahaoui, H.; van der Maarel, M. J. E. C.; Dijkhuizen, L.

    2002-01-01

    Fructosyltransferase (FTF) enzymes produce fructose polymers (fructans) from sucrose. Here, we report the isolation and characterization of an FTF-encoding gene from Lactobacillus reuteri strain 121. A C-terminally truncated version of the ftf gene was successfully expressed in Escherichia coli. When incubated with sucrose, the purified recombinant FTF enzyme produced large amounts of fructo-oligosaccharides (FOS) with β-(2→1)-linked fructosyl units, plus a high-molecular-weight fructan polymer (>107) with β-(2→1) linkages (an inulin). FOS, but not inulin, was found in supernatants of L. reuteri strain 121 cultures grown on medium containing sucrose. Bacterial inulin production has been reported for only Streptococcus mutans strains. FOS production has been reported for a few bacterial strains. This paper reports the first-time isolation and molecular characterization of (i) a Lactobacillus ftf gene, (ii) an inulosucrase associated with a generally regarded as safe bacterium, (iii) an FTF enzyme synthesizing both a high molecular weight inulin and FOS, and (iv) an FTF protein containing a cell wall-anchoring LPXTG motif. The biological relevance and potential health benefits of an inulosucrase associated with an L. reuteri strain remain to be established. PMID:12200292

  12. A simple strategy for synthesizing highly luminescent carbon nanodots and application as effective down-shifting layers

    NASA Astrophysics Data System (ADS)

    Han, Xugen; Zhong, Sihua; Pan, Wei; Shen, Wenzhong

    2015-02-01

    We propose a novel strategy to prepare highly luminescent carbon nanodots (C-dots) by employing a hydrothermal method with citric acid as the carbon source and ethylenediamine as the nitrogen source, together with adding moderate ammonia water (AW) to achieve both appropriate inner structure and excellent N passivation. The effect of pH value and AW amount on the luminescence properties has been thoroughly investigated. The photoluminescence quantum yield of the resultant C-dots reaches as high as 84.8%, which is of 10.56% higher than that of the C-dots synthesized in the absence of AW in the reaction precursors. We have further combined the highest luminescent C-dots with polyvinyl alcohol to form luminescent down-shifting layers on silicon nanowire solar cells. An effective enhancement of short-circuit current density has been realized and the contribution of the down-shifting has been extracted quantitatively from the deterioration of surface reflectance and the gain of the optical absorption redistribution by means of a theoretical model on external quantum efficiency analysis.

  13. 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.

  14. 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.

  15. High Electron Mobility Transistors For Millimeter Wave And High Speed Digital IC Applications

    NASA Astrophysics Data System (ADS)

    Gupta, Aditya K.; Higgins, J. A.; Lee, Chien-Ping

    1988-02-01

    High Electron Mobility Transistors (HEMTs) are currently regarded as the most promising three-terminal devices for ultra-high-speed digital and monolithic millimeter-wave integrated circuits. In their most basic form, these devices consist of a GaAs-MESFET-like FET fabricated on a (A1,Ga)As/GaAs epitaxial layer. The (A1,Ga)As layer is highly doped n-type and the GaAs layer is undoped. Due to the lower electron affinity of (A1,Ga)As, free electrons diffuse out of the doped layer into undoped GaAs where they form a two-dimensional electron gas near the heterointerface. Since the electrons and ionized donors are spatially separated, ionized impurity scattering is reduced and electron transport properties at the heterointerface are comparable to pure GaAs. FETs fabricated on these hetero-junctions offer many advantages such as (i) a small gate-to-channel separation which leads to extremely high transconductances; (ii) high f due to improved electron transport properties; (iii) a small source resistance; and (ivy a small saturation voltage. The benefits improve substantially upon cooling the device. In a mere seven years, HEMT technology has evolved from simple ring oscillators to circuits of LSI complexity such as 16K SRAMs. The speed performance demonstrated by this relatively immature technology has already surpassed all other semiconductor technologies. Ring oscillator gate delays of 5.8 ps at 77K and 10.2 ps at 300K have been achieved using'0.35 μm gate length devices. In the analog domain, HEMTs are the leaders in low noise and high gain amplification. At room temperatures, devices with a noise figure of 2.4 dB at 62 GHz and fmax > 250 GHz have been demonstrated.

  16. 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. PMID:26773611

  17. 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.

  18. 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.

  19. 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.

  20. 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

    2015-04-01

    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.

  1. Ultra-High-Throughput Screening of an In Vitro-Synthesized Horseradish Peroxidase Displayed on Microbeads Using Cell Sorter

    PubMed Central

    Zhu, Bo; Mizoguchi, Takuro; Kojima, Takaaki; Nakano, Hideo

    2015-01-01

    The C1a isoenzyme of horseradish peroxidase (HRP) is an industrially important heme-containing enzyme that utilizes hydrogen peroxide to oxidize a wide variety of inorganic and organic compounds for practical applications, including synthesis of fine chemicals, medical diagnostics, and bioremediation. To develop a ultra-high-throughput screening system for HRP, we successfully produced active HRP in an Escherichia coli cell-free protein synthesis system, by adding disulfide bond isomerase DsbC and optimizing the concentrations of hemin and calcium ions and the temperature. The biosynthesized HRP was fused with a single-chain Cro (scCro) DNA-binding tag at its N-terminal and C-terminal sites. The addition of the scCro-tag at both ends increased the solubility of the protein. Next, HRP and its fusion proteins were successfully synthesized in a water droplet emulsion by using hexadecane as the oil phase and SunSoft No. 818SK as the surfactant. HRP fusion proteins were displayed on microbeads attached with double-stranded DNA (containing the scCro binding sequence) via scCro-DNA interactions. The activities of the immobilized HRP fusion proteins were detected with a tyramide-based fluorogenic assay using flow cytometry. Moreover, a model microbead library containing wild type hrp (WT) and inactive mutant (MUT) genes was screened using fluorescence-activated cell-sorting, thus efficiently enriching the WT gene from the 1:100 (WT:MUT) library. The technique described here could serve as a novel platform for the ultra-high-throughput discovery of more useful HRP mutants and other heme-containing peroxidases. PMID:25993095

  2. 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

  3. 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

  4. 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.

  5. Digital metamaterials

    NASA Astrophysics Data System (ADS)

    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.

  6. 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. PMID:25218061

  7. Performance characteristics of high-resolution charge-coupled device film digitizers

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Chung B.; Butson, Philip D.; Lin, Jyh-Shyan; Li, Huai; Freedman, Matthew T.; Mun, Seong K.

    1995-05-01

    This paper describes the performance characteristics of two high resolution charged-coupled device (CCD) film scanners for radiological imaging. The two models of recently developed CCD film scanners made by DBA Systems have been available on the market for ultra high resolution film digitization. One model of the scanner digitizes the film at 21 micrometers and the other one at 42 micrometers . Both systems can be interfaced to a PC. Line-pair, star-pattern and single edge on films were used to test the spatial resolution in the directions perpendicular and parallel to the CCD scan line. Step wedges generated on films through a mammographic system and print transparencies were employed to test the gray value versus the optical density response and variations on a `uniform area.' Geometric distortion of the digitized images was determined to be negligible at less than 1%. This gray value versus optical density response was linearly plotted from optical density (OD) 0 to 2.8. Depending upon optical density regions, gray value fluctuations varied. Both ultra high resolution CCD scanners showed reasonable performance. However, some digital noises were shown in the high OD range.

  8. A technique for estimating rangeland canopy-gap size distributions from high resolution digital imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The amount and distribution of gaps in vegetation canopy is a useful indicator of multiple ecosystem processes and functions. We describe a semi-automated approach for estimating canopy-gap size distributions in rangelands from high-resolution (HR) digital images using image interpretation by observ...

  9. 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…

  10. 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…

  11. 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.

  12. 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.

  13. Emulation of high-frequency substrate noise generation in CMOS digital circuits

    NASA Astrophysics Data System (ADS)

    Shimazaki, Shunsuke; Taga, Shota; Makita, Tetsuya; Azuma, Naoya; Miura, Noriyuki; Nagata, Makoto

    2014-01-01

    A noise emulator is based on the capacitor charging modeling and generates power and substrate noises expected in a CMOS digital integrated circuit. An off-chip near-magnetic-field sensor indirectly characterizes the distribution of clock timing and the adjustability of skews within on-chip digital circuits. An on-chip noise monitor captures power and substrate noise waveforms and evaluates noise frequency components in a wide frequency bandwidth. A 65 nm CMOS prototype demonstrated power and substrate noise generation in a variety of operating scenarios of digital integrated circuits. Power noise generation emulated at 125 MHz exhibits the enhancements of high-order harmonic components after deskewing at a timing resolution of 37.8 ps, as is specifically seen in more than 10 dB enlargement of the substrate noise component at 2.1 GHz.

  14. Structure and luminescence behaviour of as-synthesized, calcined, and restored MgAlEu-LDH with high crystallinity.

    PubMed

    Zhao, Yushuang; Li, Ji-Guang; Fang, Fang; Chu, Nankai; Ma, Hui; Yang, Xiaojing

    2012-10-21

    Highly crystalline Eu(3+)-incorporated MgAl layered double hydroxides (LDHs) were synthesized by the homogeneous precipitation method. For the crystals as-prepared, after their calcination from 200-1000 °C, and, further, after restoration in a Na(2)CO(3) solution, the structural and luminescent changes were investigated for the first time. Eu(3+) ions with a coordination number of, probably, 8, were incorporated into the hydrotalcite layer, which led to a basal spacing (d(basal)) increase, microstrain formation, and crystalline morphology imperfections, while retaining the original lattice symmetry, R3[combining macron]m. In the deconstruction process due to calcination, the Eu(3+) ions restrained the formation of the spinel phase from the layered double oxide (LDO), but did not significantly change the memory effect, by which LDOs can convert to LDHs during the hydration process. For the reversible phase transformation between LDH and LDO, the morphology observation revealed that, in addition to the formation of pores on the surface, nano-slabs were formed, especially for the restored crystals. A layered phase with a d(basal) of 5.8 Å, due to bridging bidentate carbonates with the hydrotalcite layer, was formed in the calcination process at low temperature (300 °C) before the formation of LDO, but could not be restored to a large spacing. Typical (5)D(0) → (7)F(J) (J = 0-4) transitions of Eu(3+) at 579, 593, 615, 653, and 698 nm were observed in the photoluminescence spectra and the intensity of the dominating 615 nm band decreased with the LDH deconstruction and the formation of free water, and then increased with the formation of LDOs in the calcination process, and vice versa in the reconstruction process. The Eu(3+) ions had a probable 9- or 10-coordination mode in addition to the probable 8-coordination mode as the spinel phase appeared. PMID:22930336

  15. Digital High Speed Interconnects: A Study Of The Optical Alternative

    NASA Astrophysics Data System (ADS)

    Hartman, Davis H.

    1986-10-01

    The use of optics as an alternative method for achieving very high speed (10 Gb/s > bit rate > 500 Mb/s) electrical interconnects is the subject of this paper. Optical interconnect media considered include plastic channel waveguides, glass waveguides, fibers, and free-space interconnects. Typical interconnection distances considered are inches or less. The problems of cou-pling and interconnecting and their overall effect on system power budgets are also discussed. As a means of quantifying the results, link budgets for a 565 Mb/s, a 2.3 Gb/s, and a 4.6 Gb/s interconnect scenario are made. Multipoint as well as single-point-to-single-point situations are considered.

  16. Design of a W-band Stepped-frequency Synthesizer with Fast Frequency Switching

    NASA Astrophysics Data System (ADS)

    Wu, Tao; Tang, Xiaohong; Xiao, Fei

    2009-08-01

    In this paper, a W-band coherent stepped-frequency synthesizer is proposed, which provides transmitter and local oscillator signals to a high range resolution radar system. This synthesizer is realized by combining the technique of direct digital synthesizer, phase lock loop, up-conversion and multiplier chain, etc. In order to shorten the lock time of the phase lock loop, a new method is introduced in the design of this synthesizer. Measurement results show that the transmitting signal is around 94 GHz, the bandwidth is 504 MHz, the phase noise is about -90 dBc/Hz at 10 kHz offset, and the spurious signals are less than -55 dBc. Especially, the frequency switching time of this synthesizer is about 1 μs. With the W-band stepped-frequency synthesizer, the range resolution of the high range resolution radar system is better than 0.6 m.

  17. Noble Gases Analyses of Samples Synthesized at High P and T in a Multi Anvil Press Device: Protocol and Implications

    NASA Astrophysics Data System (ADS)

    Bonnefoy, B.; Andrault, D.; Moreira, M.; Bolfan-Casanova, N.

    2007-12-01

    Noble gases (He-Ne-Ar-Kr-Xe) in mantle-derived samples allow an undisputable tracing of different sources of materials. Concerning the deep mantle part, the study of noble gases suggests that a "primordial" component (which is non or partially degassed) exists. Nevertheless, this conclusion is challenged by several observations, both geophysical and geochemical, suggesting that contrariwise the mantle is now totally depleted, degassed or renewed by convection. Furthermore, the lack of experimental data disables quantitative modelling of geochemistry processes. It is still unknown how much the fractionations are dependent on the conditions on pressure, temperature and chemical composition in the mantle. Recent studies [1-3] suggest a more incompatible behavior for noble gases in comparison to their parent element (K for Ar, U + Th for He) in very specific conditions of pressure, temperature, and chemical composition. Nevertheless, those studies focus on only particular compositions or pressures or only one single noble gas. No exhaustive studies (of all nobles gases at different pressures, temperatures and compositions) were accomplished on this subject so far. We set up a new experimental protocol allowing the analyses of rare gases in samples synthesized under mantle conditions, at high pressures and temperatures. This new protocol associates the use of a gas loading device [4], a multi-anvil press device (INSU MAP, Clermont-Ferrand, France), a laser ablation coupled to mass- spectrometer for the noble gases analysis (excimer laser, λ = 193 nm), and a 3D profilometry device to quantify the amount of ablated material. We will present an application of these methods on the noble gases partitioning between solid and liquid natural phases in the 3-5 GPa pressure range and for temperature of 1400 to 1600°C. [1] E.M. Chamorro, R.A Brooker, J.-A Wartho, B.J. Wodd, S.P. Kelley and J.D. Blundy. Ar and K partitioning between clinopyroxene and silicate melt to 8 GPa

  18. A novel algorithm combining oversampling and digital lock-in amplifier of high speed and precision

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhou, Mei; He, Feng; Lin, Ling

    2011-09-01

    Because of a large amount of arithmetic in the standard digital lock-in detection, a high performance processor is needed to implement the algorithm in real time. This paper presents a novel algorithm that integrates oversampling and high-speed lock-in detection. The algorithm sets the sampling frequency as a whole-number multiple of four of the input signal frequency, and then uses the common downsampling technology to lower the sampling frequency to four times of the input signal frequency. It could effectively remove the noise interference and improve the detection accuracy. After that the phase sensitive detector is implemented. It simply does the addition and subtraction on four points in the period of same phase and replaces almost all the multiplication operations to speed up digital lock-in detection calculation substantially. Furthermore, the correction factor is introduced to improve the calculation accuracy of the amplitude, and an error caused by the algorithm in theory can be eliminated completely. The results of the simulation and actual experiments show that the novel algorithm combining digital lock-in detection and oversampling not only has the high precision, but also has the unprecedented speed. In our work, the new algorithm is suitable for the real-time weak signal detection in the general microprocessor not just digital signal processor.

  19. Digital avionics susceptibility to high energy radio frequency fields

    NASA Astrophysics Data System (ADS)

    Larsen, William E.

    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.

  20. 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.

  1. High resolution heterodyne interferometer based on time-to-digital converter.

    PubMed

    Wang, Fei; Long, Zhangcai; Zhang, Bin; Zhao, Meirong

    2012-04-01

    A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase∕quadrature (I∕Q) method. PMID:22559581

  2. High resolution heterodyne interferometer based on time-to-digital converter

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Long, Zhangcai; Zhang, Bin; Zhao, Meirong

    2012-04-01

    A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase/quadrature (I/Q) method.

  3. A digitally configurable measurement platform using audio cards for high-resolution electronic transport studies.

    PubMed

    Gopman, D B; Bedau, D; Kent, A D

    2012-05-01

    We report on a software-defined digitally configurable measurement platform for determining electronic transport properties in nanostructures with small readout signals. By using a high-resolution audio analog-to-digital/digital-to-analog converter in a digitally compensated bridge configuration we significantly increase the measurement speed compared to established techniques and simultaneously acquire large and small signal characteristics. We characterize the performance (16 bit resolution, 100 dB dynamic range at 192 kS/s) and demonstrate the application of this measurement platform for studying the transport properties of spin-valve nanopillars, a two-terminal device that exhibits giant magnetoresistance and whose resistance can be switched between two levels by applied magnetic fields and by currents applied by the audio card. The high resolution and fast sampling capability permits rapid acquisition of deep statistics on the switching of a spin-valve nanopillar and reduces the time to acquire the basic properties of the device - a state-diagram showing the magnetic configurations as function of applied current and magnetic field - by orders of magnitude. PMID:22667635

  4. 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.

  5. A digitally configurable measurement platform using audio cards for high-resolution electronic transport studies

    NASA Astrophysics Data System (ADS)

    Gopman, D. B.; Bedau, D.; Kent, A. D.

    2012-05-01

    We report on a software-defined digitally configurable measurement platform for determining electronic transport properties in nanostructures with small readout signals. By using a high-resolution audio analog-to-digital/digital-to-analog converter in a digitally compensated bridge configuration we significantly increase the measurement speed compared to established techniques and simultaneously acquire large and small signal characteristics. We characterize the performance (16 bit resolution, 100 dB dynamic range at 192 kS/s) and demonstrate the application of this measurement platform for studying the transport properties of spin-valve nanopillars, a two-terminal device that exhibits giant magnetoresistance and whose resistance can be switched between two levels by applied magnetic fields and by currents applied by the audio card. The high resolution and fast sampling capability permits rapid acquisition of deep statistics on the switching of a spin-valve nanopillar and reduces the time to acquire the basic properties of the device - a state-diagram showing the magnetic configurations as function of applied current and magnetic field - by orders of magnitude.

  6. Highly crystalline LiCuXFe1‑XPO4 nanoparticles synthesized by high temperature thermal decomposition: a morphological and electrical transport study

    NASA Astrophysics Data System (ADS)

    Martinez, P.; Ruiz, F.; Curiale, J.; Vasquez Mansilla, M.; Zysler, R. D.; Dada, L.; Moreno, M. S.; Rodríguez, L.; Fregenal, D.; Bernardi, G.; Lima, E., Jr.

    2016-08-01

    In this work, we report the morphological and electrical characterization of highly crystalline \\text{LiC}{{\\text{u}}\\text{X}}\\text{F}{{\\text{e}}1-\\text{X}}\\text{P}{{\\text{O}}4} nanoparticles synthesized via the high-temperature (380 °C) thermal decomposition of organometallic precursors. The mean diameter of the studied nanoparticles was 30–40 nm. The Cu/Fe relations of 0, 0.001 and 0.042 for the three studied samples were obtained via particle-induced x-ray emission spectroscopy. Crystallographic and morphological studies were performed using x-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy techniques. We investigated the effects of incorporating copper on the electric transport properties of this highly crystalline nanometric system using impedance spectroscopy and DC transport techniques. The experimental evidence allowed us to conclude that in the frequency range f  <  1 kHz the transport is dominated by the diffusion of Li and the presence of Cu atoms in the systems hinders this transport mechanism, despite the high crystallinity of the system.

  7. 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.

  8. One-Pot Microbial Method to Synthesize Dual-Doped Graphene and Its Use as High-Performance Electrocatalyst

    PubMed Central

    Guo, Peipei; Xiao, Fei; Liu, Qian; Liu, Hongfang; Guo, Yunlong; Gong, Jian Ru; Wang, Shuai; Liu, Yunqi

    2013-01-01

    A novel strategy to synthesize nitrogen (N) and sulfur (S)-doped graphene (G) is developed through sulfate-reducing bacteria treating graphene oxide (GO). The N, S-doped G demonstrates significantly improved electrocatalytic properties and electrochemical sensing performances in comparison with single-doped graphene due to the synergistic effects of dual dopants on the properties of graphene. PMID:24336153

  9. Why mental arithmetic counts: brain activation during single digit arithmetic predicts high school math scores.

    PubMed

    Price, Gavin R; Mazzocco, Michèle M M; Ansari, Daniel

    2013-01-01

    Do individual differences in the brain mechanisms for arithmetic underlie variability in high school mathematical competence? Using functional magnetic resonance imaging, we correlated brain responses to single digit calculation with standard scores on the Preliminary Scholastic Aptitude Test (PSAT) math subtest in high school seniors. PSAT math scores, while controlling for PSAT Critical Reading scores, correlated positively with calculation activation in the left supramarginal gyrus and bilateral anterior cingulate cortex, brain regions known to be engaged during arithmetic fact retrieval. At the same time, greater activation in the right intraparietal sulcus during calculation, a region established to be involved in numerical quantity processing, was related to lower PSAT math scores. These data reveal that the relative engagement of brain mechanisms associated with procedural versus memory-based calculation of single-digit arithmetic problems is related to high school level mathematical competence, highlighting the fundamental role that mental arithmetic fluency plays in the acquisition of higher-level mathematical competence. PMID:23283330

  10. 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%.