WorldWideScience

Sample records for monolithic phased arrays

  1. A Ferrite LTCC-Based Monolithic SIW Phased Antenna Array

    KAUST Repository

    Nafe, Ahmed

    2016-11-17

    In this work, we present a novel configuration for realizing monolithic SIW-based phased antenna arrays using Ferrite LTCC technology. Unlike the current common schemes for realizing SIW phased arrays that rely on surface-mount component (p-i-n diodes, etc) for controlling the phase of the individual antenna elements, here the phase is tuned by biasing of the ferrite filling of the SIW. This approach eliminates the need for mounting of any additional RF components and enables seamless monolithic integration of phase shifters and antennas in SIW technology. As a proof of concept, a two-element slotted SIW-based phased array is designed, fabricated and measured. The prototype exhibits a gain of 4.9 dBi at 13.2 GHz and a maximum E-plane beam-scanning of 28 degrees using external windings for biasing the phase shifters. Moreover, the array can achieve a maximum beam-scanning of 19 degrees when biased with small windings that are embedded in the package. This demonstration marks the first time a fully monolithic SIW-based phased array is realized in Ferrite LTCC technology and paves the way for future larger-size implementations.

  2. Monolithic Microwave Integrated Circuit (MMIC) Phased Array Demonstrated With ACTS

    Science.gov (United States)

    1996-01-01

    Monolithic Microwave Integrated Circuit (MMIC) arrays developed by the NASA Lewis Research Center and the Air Force Rome Laboratory were demonstrated in aeronautical terminals and in mobile or fixed Earth terminals linked with NASA's Advanced Communications Technology Satellite (ACTS). Four K/Ka-band experimental arrays were demonstrated between May 1994 and May 1995. Each array had GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The 30-GHz transmit array used in uplinks to ACTS was developed by Lewis and Texas Instruments. The three 20-GHz receive arrays used in downlinks from ACTS were developed in cooperation with the Air Force Rome Laboratory, taking advantage of existing Air Force integrated-circuit, active-phased-array development contracts with the Boeing Company and Lockheed Martin Corporation. Four demonstrations, each related to an application of high interest to both commercial and Department of Defense organizations, were conducted. The location, type of link, and the data rate achieved for each of the applications is shown. In one demonstration-- an aeronautical terminal experiment called AERO-X--a duplex voice link between an aeronautical terminal on the Lewis Learjet and ACTS was achieved. Two others demonstrated duplex voice links (and in one case, interactive video links as well) between ACTS and an Army high-mobility, multipurpose wheeled vehicle (HMMWV, or "humvee"). In the fourth demonstration, the array was on a fixed mount and was electronically steered toward ACTS. Lewis served as project manager for all demonstrations and as overall system integrator. Lewis engineers developed the array system including a controller for open-loop tracking of ACTS during flight and HMMWV motion, as well as a laptop data display and recording system used in all demonstrations. The Jet Propulsion Laboratory supported the AERO-X program, providing elements of the ACTS Mobile Terminal. The successful

  3. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    Science.gov (United States)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-02-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  4. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    Science.gov (United States)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  5. Phased-Array Monolithic PEM for FT Spectrometry With Applications in Explosive Detection and CB Defense

    Science.gov (United States)

    2008-12-01

    1 PHASED-ARRAY MONOLITHIC PEM FOR FT SPECTROMETRY WITH APPLICATIONS IN EXPLOSIVE DETECTION AND CB DEFENSE Tudor N. Buican* Semiotic ...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Semiotic Engineering Associates LLC Albuquerque, NM 87108 8. PERFORMING ORGANIZATION REPORT NUMBER 9

  6. Diffraction coupled phase-locked arrays of quantum cascade lasers with monolithically integrated Talbot cavities

    CERN Document Server

    Wang, Lei; Jia, Zhi-Wei; Zhao, Yue; Liu, Chuan-Wei; Liu, Ying-Hui; Zhai, Shen-Qiang; Zhuo, Ning; Liu, Feng-Qi; Xu, Xian-Gang

    2016-01-01

    Diffraction coupled arrays of quantum cascade laser are presented. The phase-locked behavior is achieved through monolithic integration of a Talbot cavity at one side of the laser array. The principle is based on fractional Talbot effect. By controlling length of Talbot cavity to be a quarter of Talbot distance (Zt/4), in-phase mode operation is selected. Measured far-field radiation patterns reflect stable in-phase mode operation under different injection currents, from threshold current to full power current. Diffraction-limited performance is shown from the lateral far-field, where three peaks can be obtained and main peak and side peak interval is 10.5{\\deg}. The phase-locked arrays with in-phase mode operation may be a feasible solution to get higher output power and maintain well beam quality meanwhile.

  7. Phased array of high-power, coherent, monolithic flared amplifier master oscillator power amplifiers

    Science.gov (United States)

    Osinski, J. S.; Mehuys, D.; Welch, D. F.; Waarts, R. G.; Major, J. S., Jr.; Dzurko, K. M.; Lang, R. J.

    1995-01-01

    A monolithically integrated array of InGaAs/AlGaAs flared amplifiers driven by a single DBR laser through a power splitter network and individually addressed phase modulators is described. Phase adjustment of ≳2π per element by free-carrier effects is verified by monitoring the interference pattern of all four emitters, and typically requires <15 mA of current to obtain a 2π phase shift. Phase matching is achieved among all four diffraction-limited emitters at a pulsed output power of ≳5 W, and, combined with the proper external lensing, could therefore result in an ultranarrow, single-lobed far-field pattern whose width is determined by the extended aperture of the array.

  8. Cantilever RF-MEMS for monolithic integration with phased array antennas on a PCB

    Science.gov (United States)

    Aguilar-Armenta, C. J.; Porter, S. J.

    2015-12-01

    This article presents the development and operation of a novel electrostatic metal-to-metal contact cantilever radio-frequency microelectromechanical system (RF-MEMS) switch for monolithic integration with microstrip phased array antennas (PAAs) on a printed circuit board. The switch is fabricated using simple photolithography techniques on a Rogers 4003c substrate, with a footprint of 200 µm × 100 µm, based on a 1 µm-thick copper cantilever. An alternative wet-etching technique for effectively releasing the cantilever is described. Electrostatic and electromagnetic measurements show that the RF-MEMS presents an actuation voltage of 90 V for metal-to-metal contact, an isolation of -8.7 dB, insertion loss of -2.5 dB and a return loss of -15 dB on a 50 Ω microstrip line at 12.5 GHz. For proof-of-concept, a beam-steering 2 × 2 microstrip PAA, based on two 1-bit phase shifters suitable for the monolithic integration of the RF-MEMS, has been designed and measured at 12.5 GHz. Measurements show that the beam-steering system presents effective radiation characteristics with scanning capabilities from broadside towards 29° in the H-plane.

  9. High-power coherent phased array of monolithic flared amplifier-master oscillator power amplifiers (MFA-MOPAs)

    Science.gov (United States)

    Osinski, Jules S.; Mehuys, David G.; Welch, David F.; Dzurko, Kenneth M.; Lang, Robert J.

    1995-04-01

    A monolithically integrated array of InGaAs/AlGaAs flared amplifiers driven by a single DBR laser through a power splitter network and individually addressed phase modulators is described. Phase adjustment of > 2(pi) per element by free-carrier effects is verified by monitoring the interference pattern of 4 emitters, and typically requires 5 W, and, combined with the proper external lensing, could therefore result in an ultra-narrow, single-lobed far-field pattern whose width is determined by the extended aperture of the array. This architecture is capable of providing single-mode, diffraction-limited performance from each emitter and is scalable to unprecedented power levels. Over 20 W of pulsed, spectrally coherent emission is generated at 955 nm from a 4-element array, and 39 W is obtained from an 8-element array.

  10. Monolithic Time Delay Integrated APD Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the proposed program by Epitaxial Technologies is to develop monolithic time delay integrated avalanche photodiode (APD) arrays with sensitivity...

  11. Development of a monolithic ferrite memory array

    Science.gov (United States)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  12. Monolithic aerogels with nanoporous crystalline phases

    Science.gov (United States)

    Daniel, Christophe; Guerra, Gaetano

    2015-05-01

    High porosity monolithic aerogels with nanoporous crystalline phases can be obtained from syndiotactic polystyrene and poly(2,6-dimethyl-1,4-phenylene)oxide thermoreversible gels by removing the solvent with supercritical CO2. The presence of crystalline nanopores in the aerogels based on these polymers allows a high uptake associated with a high selectivity of volatile organic compounds from vapor phase or aqueous solutions even at very low activities. The sorption and the fast kinetics make these materials particularly suitable as sorption medium to remove traces of pollutants from water and moist air.

  13. Monolithic microwave integrated circuit devices for active array antennas

    Science.gov (United States)

    Mittra, R.

    1984-01-01

    Two different aspects of active antenna array design were investigated. The transition between monolithic microwave integrated circuits and rectangular waveguides was studied along with crosstalk in multiconductor transmission lines. The boundary value problem associated with a discontinuity in a microstrip line is formulated. This entailed, as a first step, the derivation of the propagating as well as evanescent modes of a microstrip line. The solution is derived to a simple discontinuity problem: change in width of the center strip. As for the multiconductor transmission line problem. A computer algorithm was developed for computing the crosstalk noise from the signal to the sense lines. The computation is based on the assumption that these lines are terminated in passive loads.

  14. Monolithic Gradient Index Phase Plate Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The "piston errors" and aberrations of the mirror segments used in large telescopes, are typically measured with on-board optical instruments, usually a dispersed...

  15. Effect of the presence of an ordered micro-pillar array on the formation of silica monoliths.

    Science.gov (United States)

    Detobel, Frederik; Eghbali, Hamed; De Bruyne, Selm; Terryn, Herman; Gardeniers, Han; Desmet, Gert

    2009-10-30

    We report on the synthesis of siloxane-based monoliths in the presence of a two-dimensional, perfectly ordered array of micro-pillars. Both methyltrimethoxysilane- and tetramethoxysilane-based monoliths were considered. The obtained structures were analyzed using scanning-electron microscopy and can be explained from the general theory of surface-directed phase separation in confined spaces. The formed structures are to a large extent nearly exclusively determined by the ratio between the bulk domain size of the monolith on the one hand and the distance between the micro-pillars on the other hand. When this ratio is small, the presence of the pillars has nearly no effect on the morphology of the produced monoliths. However, when the ratio approaches unity and ascends above it, some new types of monolith morphologies are induced, two of which appear to have interesting properties for use as novel chromatographic supports. One of these structures (obtained when the domain size/inter-pillar distance ratio is around unity) is a 3D network of linear interconnections between the pillars, organized such that all skeleton branches are oriented perpendicular to the micro-pillar surface. A second interesting structure is obtained at even higher values of the domain size/inter-pillar distance ratio. In this case, each individual micro-pillar is uniformly coated with a mesoporous shell.

  16. Array Phase Shifters: Theory and Technology

    Science.gov (United States)

    Romanofsky, Robert R.

    2007-01-01

    While there are a myriad of applications for microwave phase shifters in instrumentation and metrology, power combining, amplifier linearization, and so on, the most prevalent use is in scanning phased-array antennas. And while this market continues to be dominated by military radar and tracking platforms, many commercial applications have emerged in the past decade or so. These new and potential applications span low-Earth-orbit (LEO) communications satellite constellations and collision warning radar, an aspect of the Intelligent Vehicle Highway System or Automated Highway System. In any case, the phase shifters represent a considerable portion of the overall antenna cost, with some estimates approaching 40 percent for receive arrays. Ferrite phase shifters continue to be the workhorse in military-phased arrays, and while there have been advances in thin film ferrite devices, the review of this device technology in the previous edition of this book is still highly relevant. This chapter will focus on three types of phase shifters that have matured in the past decade: GaAs MESFET monolithic microwave integrated circuit (MMIC), micro-electromechanical systems (MEMS), and thin film ferroelectric-based devices. A brief review of some novel devices including thin film ferrite phase shifters and superconducting switches for phase shifter applications will be provided. Finally, the effects of modulo 2 phase shift limitations, phase errors, and transient response on bit error rate degradation will be considered.

  17. Nonlinear phased array imaging

    Science.gov (United States)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  18. Monolithic blue LED series arrays for high-voltage AC operation

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping [Satellite Venture Business Laboratory, University of Tokushima, Tokushima 770-8506 (Japan); Sato, Hisao; Mizobuchi, Takashi; Morioka, Kenji; Kawano, Shunsuke; Muramoto, Yoshihiko; Sato, Daisuke; Sakai, Shiro [Nitride Semiconductor Co. Ltd., Naruto, Tokushima 771-0360 (Japan); Lee, Young-Bae; Ohno, Yasuo [Department of Electrical and Electronic Engineering, University of Tokushima, Tokushima 770-8506 (Japan)

    2002-12-16

    Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 {mu}m x 120 {mu}m and the total size is 1.1 mm x 1 mm for a 40(20+20) LED array. Deep dry etching was performed as device isolation. Two-layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On-wafer measurement shows that the output power is 40 mW for 40(20+20) LED array under ac 72 V. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  19. Progress toward a monolithically integrated coherent diode laser array

    Science.gov (United States)

    Evans, G. A.; Garmire, E. M.; Stoll, H. M.; Osmer, J. A.; Soady, W. E.; Lee, A. B.; Ziegler, M. P.

    1981-02-01

    Progress toward the design and fabrication of a GaAlAs semiconductor laser array capable of high average power levels (0.1 to 1.0 watt) and low (approx 1 millirad) beam divergence is reported. A large optical cavity (LOC) configuration is grown by liquid phase epitaxy. The LOC structure is characterized by photoluminescence scans, ion microprobe mass analysis (IMMA), and optical waveguiding measurements. Fabry-Perot, active-passive, and DBR lasers are fabricated using chemical and ion beam etching. Gratings formed using holographic and ion beam etching techniques provide third order feedback for the DBR lasers, and are also used as distributed beam deflectors (DBDs) and output couplers. Comparisons of the results of experiments performed on DBR lasers, DBDs, and coupled lasers are made with theoretical models. Details of the material growth, material characterization, device fabrication, experiments, and theoretical models are presented in this report.

  20. Mixed Frequency Ultrasound Phased Array

    Institute of Scientific and Technical Information of China (English)

    香勇; 霍健; 施克仁; 陈以方

    2004-01-01

    A mixed frequency ultrasonic phased array (MPA) was developed to improve the focus, in which the element excitation frequencies are not all the same as in a normal constant frequency phased array. A theoretical model of the mixed frequency phased array based on the interference principle was used to simulate the array's sound distribution. The pressure intensity in the array focal area was enhanced and the scanning area having effective contrast resolution was enlarged. The system is especially useful for high intensity focused ultrasound (HIFU) with more powerful energy and ultrasound imaging diagnostics with improved signal to noise ratios, improved beam forming and more uniform imaging quality.

  1. Polymethacrylate monolithic and hybrid particle-monolithic columns for reversed-phase and hydrophilic interaction capillary liquid chromatography.

    Science.gov (United States)

    Jandera, Pavel; Urban, Jirí; Skeríková, Veronika; Langmaier, Pavel; Kubícková, Romana; Planeta, Josef

    2010-01-01

    We prepared hybrid particle-monolithic polymethacrylate columns for micro-HPLC by in situ polymerization in fused silica capillaries pre-packed with 3-5microm C(18) and aminopropyl silica bonded particles, using polymerization mixtures based on laurylmethacrylate-ethylene dimethacrylate (co)polymers for the reversed-phase (RP) mode and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl) zwitterionic (co)polymers for the hydrophilic interaction (HILIC) mode. The hybrid particle-monolithic columns showed reduced porosity and hold-up volumes, approximately 2-2.5 times lower in comparison to the pure monolithic columns prepared in the whole volume of empty capillaries. The elution volumes of sample compounds are also generally lower in comparison to packed or pure monolithic columns. The efficiency and permeability of the hybrid columns are intermediate in between the properties of the reference pure monolithic and particle-packed columns. The chemistries of the embedded solid particles and of the interparticle monolithic moiety in the hybrid capillary columns contribute to the retention to various degrees, affecting the selectivity of separation. Some hybrid columns provided improved separations of proteins in comparison to the reference particle-packed columns in the reversed-phase mode. Zwitterionic hybrid particle-monolithic columns show dual mode retention HILIC/RP behaviour depending on the composition of the mobile phase and allow separations of polar compounds such as phenolic acids in the HILIC mode at lower concentrations of acetonitrile and, often in shorter analysis time in comparison to particle-packed and full-volume monolithic columns.

  2. Magnetism-Enhanced Monolith-Based In-Tube Solid Phase Microextraction.

    Science.gov (United States)

    Mei, Meng; Huang, Xiaojia; Luo, Qing; Yuan, Dongxin

    2016-02-02

    Monolith-based in-tube solid phase microextraction (MB/IT-SPME) has received wide attention because of miniaturization, automation, expected loading capacity, and environmental friendliness. However, the unsatisfactory extraction efficiency becomes the main disadvantage of MB/IT-SPME. To overcome this circumstance, magnetism-enhanced MB/IT-SPME (ME-MB/IT-SPME) was developed in the present work, taking advantage of magnetic microfluidic principles. First, modified Fe3O4 nanoparticles were mixed with polymerization solution and in situ polymerized in the capillary to obtain a magnetic monolith extraction phase. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample, and desorption solvent on the performance of ME-MB/IT-SPME were investigated in detail. The analysis of six steroid hormones in water samples by the combination of ME-MB/IT-SPME with high-performance liquid chromatography with diode array detection was selected as a paradigm for the practical evaluation of ME-MB/IT-SPME. The application of a controlled magnetic field resulted in an obvious increase of extraction efficiencies of the target analytes between 70% and 100%. The present work demonstrated that application of different magnetic forces in adsorption and desorption steps can effectively enhance extraction efficiency of MB/IT-SPME systems.

  3. A Low Phase Noise Fully Monolithic 6 GHz Differential Coupled NMOS LC-VCO

    Science.gov (United States)

    Moalla, Dorra Mellouli; Cordeau, David; Mnif, Hassene; Paillot, Jean-Marie; Loulou, Mourad

    2016-01-01

    A fully monolithic 6 GHz low-phase noise Voltage-Controlled-Oscillator (VCO) is presented in this paper. It consists in two LC-NMOS differential VCOs coupled through a resistive network and is implemented on a 0.25 µm BiCMOS SiGe process. This proposed integrated VCO can be used also for phased-array applications to steer the beam over the entire spatial range. In this case, the radiation pattern of the phased antenna array is steered in a particular direction by establishing a constant phase progression in the oscillator chain which can be obtained by detuning the free-running frequencies of the two oscillators in the array. At 2.5 V power supply voltage and a power dissipation of 62.5 mW, the coupled VCO array features a measured worst case phase noise of -102.4 dBc/Hz and -125.64 dBc/Hz at 100 kHz and 1 MHz frequency offset respectively from a 6 GHz carrier. The tuning range is about 400 MHz, from 5.85 to 6.25 GHz, for a tuning voltage varying from 0 to 2.5 V.

  4. SiGe BiCMOS front-end circuits for X-Band phased arrays

    OpenAIRE

    2012-01-01

    The current Transmit/Receive (T/R) modules have typically been implemented using GaAs- and InP-based discrete monolithic microwave integrated circuits (MMIC) to meet the high performance requirement of the present X-Band phased arrays. However their cost, size, weight, power consumption and complexity restrict phased array technology only to certain military and satellite applications which can tolerate these limitations. Therefore, next generation X-Band phased array radar systems aim to use...

  5. Effect of the presence of an ordered micro-pillar array on the formation of silica monoliths

    NARCIS (Netherlands)

    Detobel, Frederik; Eghbali, Hamed; De Bruyne, Selm; Terryn, Herman; Gardeniers, Han; Desmet, Gert

    2009-01-01

    We report on the synthesis of siloxane-based monoliths in the presence of a two-dimensional, perfectly ordered array of micro-pillars. Both methyltrimethoxysilane- and tetramethoxysilane-based monoliths were considered. The obtained structures were analyzed using scanning-electron microscopy and can

  6. Fundamentals of ultrasonic phased arrays

    CERN Document Server

    Schmerr, Lester W

    2014-01-01

    This book describes in detail the physical and mathematical foundations of ultrasonic phased array measurements.?The book uses linear systems theory to develop a comprehensive model of the signals and images that can be formed with phased arrays. Engineers working in the field of ultrasonic nondestructive evaluation (NDE) will find in this approach a wealth of information on how to design, optimize and interpret ultrasonic inspections with phased arrays. The fundamentals and models described in the book will also be of significant interest to other fields, including the medical ultrasound and

  7. Monolithic LaBr3 : Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography

    NARCIS (Netherlands)

    Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R.

    2012-01-01

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high gamma-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal arrays

  8. A linear monolithic 4-6 on silicon IR detector array

    Science.gov (United States)

    Vandamme, J.; Vermeiren, J.; Zogg, H.; Masek, J.; Fabbricotti, M.

    1992-12-01

    A linear array of monolithically grown PbTe and PbSnSe detectors on (111)-Si for MWIR and TIR imaging applications was designed and processed. The array consists of a staggered row of 2 by 128 detectors on a 100 micrometers pitch. The readout circuitry, integrated on the Si substrate consists of a COS multiplexer with a direct injection input stage, a charge reduction stage and charge to voltage conversion stage for each individual detector. This XDI (MultipeXed Direct Injection) circuit also allows for on-chip nonuniformity compensation with a switched capacitor network.

  9. A design concept for an MMIC microstrip phased array

    Science.gov (United States)

    Lee, R. Q.; Smetana, J.; Acosta, R.

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined.

  10. Modeling of phased array transducers.

    Science.gov (United States)

    Ahmad, Rais; Kundu, Tribikram; Placko, Dominique

    2005-04-01

    Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM (distributed point source method) is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.

  11. Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography

    Science.gov (United States)

    Simpson, R.; Cutler, T. E.; Danly, C. R.; Espy, M. A.; Goglio, J. H.; Hunter, J. F.; Madden, A. C.; Mayo, D. R.; Merrill, F. E.; Nelson, R. O.; Swift, A. L.; Wilde, C. H.; Zocco, T. G.

    2016-11-01

    The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

  12. Tent Shaped Phased Array Tests.

    Science.gov (United States)

    1982-01-01

    AD-A113 191 HARRIS CORP MELBOURNE FL GOVERNMENT COMMUNICATION SY-ETC Fi 20/11TENT SHAPED PHASED ARRAY TESTS.(U JAN 82 C A CHUANG F19628-79-C-T173...821714f1 45 0 +450 SCAN PLANE ARRAY PATTERNS FIG. B-31 B- 31 AD-AL13 191 HARRS CRP PMELBOURNE FLY GOVERNMENT COMMUNICATION ST--ETC F/6 20/14 TENT SHAPED

  13. EHF multifunction phased array antenna

    Science.gov (United States)

    Solbach, Klaus

    1986-07-01

    The design of a low cost demonstration EHF multifunction-phased array antenna is described. Both, the radiating elements and the phase-shifter circuits are realized on microstrip substrate material in order to allow photolithographic batch fabrication. Self-encapsulated beam-lead PIN-diodes are employed as the electronic switch elements to avoid expensive hermetic encapsulation of the semiconductors or complete circuits. A space-feed using a horn-radiator to illuminate the array from the front-side is found to be the simplest and most inexpensive feed. The phased array antenna thus operates as a reflect-array, the antenna elements employed in a dual role for the collection of energy from the feed-horn and for the re-radiation of the phase-shifted waves (in transmit-mode). The antenna is divided into modules containing the radiator/phase-shifter plate plus drive- and BITE-circuitry at the back. Both drive- and BITE-components use gate-array integrated circuits especially designed for the purpose. Several bus-systems are used to supply bias and logical data flows to the modules. The beam-steering unit utilizes several signal processors and high-speed discrete adder circuits to combine the pointing, frequency and beam-shape information from the radar system computer with the stored phase-shift codes for the array elements. Since space, weight and power consumption are prime considerations only the most advanced technology is used in the design of both the microwave and the digital/drive circuitry.

  14. Phased arrays: inline flow line hub inspection using phased arrays

    NARCIS (Netherlands)

    Bloom, J.G.P.; Chougrani, K.; Rundberg, H.; Oldenziel, G.; Deleye, X.; Martina, Q.

    2011-01-01

    The feasibility of the inspection of flow line hubs using the phased array technique was investigated to determine the surface area of the seal area degraded by corrosion. A clean model of the hub was simulated to gain insight into the geometrical echoes and to determine the area covered by the ultr

  15. Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

    Energy Technology Data Exchange (ETDEWEB)

    González, A.J.; Conde, P.; Iborra, A. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); Aguilar, A. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Bellido, P. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); García-Olcina, R. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Hernández, L.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain); Torres, J. [Communications and Digital Systems Design Group (DSDC), Universidad de Valencia (Spain); Vidal, L.F.; Benlloch, J.M. [Institute for Instrumentation in Molecular Imaging (I3M), Universidad Politécnica de Valencia – CSIC – CIEMAT (Spain)

    2015-07-01

    We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12×12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured.

  16. Airborne electronically steerable phased array

    Science.gov (United States)

    1972-01-01

    The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

  17. Development of silicon monolithic arrays for dosimetry in external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Bisello, Francesca, E-mail: francesca.bisello@iba-group.com [IBA Dosimetry GmbH, Schwarzenbruck (Germany); Friedrich-Alexander Universität Erlangen—Nürnberg, Erlangen (Germany); Menichelli, David [IBA Dosimetry GmbH, Schwarzenbruck (Germany); Scaringella, Monica [University of Florence, Firenze (Italy); INFN—Florence Division, Sesto Fiorentino (Italy); Talamonti, Cinzia; Zani, Margherita; Bucciolini, Marta [University of Florence, Firenze (Italy); Azienda Ospedaliera Unversitaria Careggi, Firenze (Italy); Bruzzi, Mara [University of Florence, Firenze (Italy); INFN—Florence Division, Sesto Fiorentino (Italy)

    2015-10-01

    New tools for dosimetry in external beam radiotherapy have been developed during last years in the framework of the collaboration among the University of Florence, INFN Florence and IBA Dosimetry. The first step (in 2007) was the introduction in dosimetry of detector solutions adopted from high energy physics, namely epitaxial silicon as the base detector material and a guard ring in diode design. This allowed obtaining state of the art radiation hardness, in terms of sensitivity dependence on accumulated dose, with sensor geometry particularly suitable for the production of monolithic arrays with modular design. Following this study, a 2D monolithic array has been developed, based on 6.3×6.3 cm{sup 2} modules with 3 mm pixel pitch. This prototype has been widely investigated and turned out to be a promising tool to measure dose distributions of small and IMRT fields. A further linear array prototype has been recently design with improve spatial resolution (1 mm pitch) and radiation hardness. This 24 cm long device is constituted by 4×64 mm long modules. It features low sensitivity changes with dose (0.2%/kGy) and dose per pulse (±1% in the range 0.1–2.3 mGy/pulse, covering applications with flattened and unflattened photon fields). The detector has been tested with very satisfactory results as a tool for quality assurance of linear accelerators, with special regards to small fields, and proton pencil beams. In this contribution, the characterization of the linear array with unflattened MV X-rays, {sup 60}Co radiation and 226 MeV protons is reported. - Highlights: • A silicon monolithic 1D array with 1 mm pixel pitch was developed. • The detector was characterized with {sup 60}Co, unflattened MV X-rays, 226 MeV protons. • Dose linearity in clinical relevance range and dose profiles were measured. • The detector performs good agreement with reference detectors. • The technology is suitable in dose profiling in MV X-ray and proton therapy.

  18. Nanoporous Monolithic Microsphere Arrays Have Anti-Adhesive Properties Independent of Humidity

    Directory of Open Access Journals (Sweden)

    Anna Eichler-Volf

    2016-05-01

    Full Text Available Bioinspired artificial surfaces with tailored adhesive properties have attracted significant interest. While fibrillar adhesive pads mimicking gecko feet are optimized for strong reversible adhesion, monolithic microsphere arrays mimicking the slippery zone of the pitchers of carnivorous plants of the genus Nepenthes show anti-adhesive properties even against tacky counterpart surfaces. In contrast to the influence of topography, the influence of relative humidity (RH on adhesion has been widely neglected. Some previous works deal with the influence of RH on the adhesive performance of fibrillar adhesive pads. Commonly, humidity-induced softening of the fibrils enhances adhesion. However, little is known on the influence of RH on solid anti-adhesive surfaces. We prepared polymeric nanoporous monolithic microsphere arrays (NMMAs with microsphere diameters of a few 10 µm to test their anti-adhesive properties at RHs of 2% and 90%. Despite the presence of continuous nanopore systems through which the inner nanopore walls were accessible to humid air, the topography-induced anti-adhesive properties of NMMAs on tacky counterpart surfaces were retained even at RH = 90%. This RH-independent robustness of the anti-adhesive properties of NMMAs significantly contrasts the adhesion enhancement by humidity-induced softening on nanoporous fibrillar adhesive pads made of the same material.

  19. Optical phased-array ladar.

    Science.gov (United States)

    Montoya, Juan; Sanchez-Rubio, Antonio; Hatch, Robert; Payson, Harold

    2014-11-01

    We demonstrate a ladar with 0.5 m class range resolution obtained by integrating a continuous-wave optical phased-array transmitter with a Geiger-mode avalanche photodiode receiver array. In contrast with conventional ladar systems, an array of continuous-wave sources is used to effectively pulse illuminate a target by electro-optically steering far-field fringes. From the reference frame of a point in the far field, a steered fringe appears as a pulse. Range information is thus obtained by measuring the arrival time of a pulse return from a target to a receiver pixel. This ladar system offers a number of benefits, including broad spectral coverage, high efficiency, small size, power scalability, and versatility.

  20. EML Array fabricated by SAG technique monolithically integrated with a buried ridge AWG multiplexer

    Science.gov (United States)

    Xu, Junjie; Liang, Song; Zhang, Zhike; An, Junming; Zhu, Hongliang; Wang, Wei

    2017-06-01

    We report the fabrication of a ten channel electroabsorption modulated DFB laser (EML) array. Different emission wavelengths of the laser array are obtained by selective area growth (SAG) technique, which is also used for the integration of electroabsorption modulators (EAM) with the lasers. An arrayed waveguide grating (AWG) combiner is integrated monolithically with the laser array by butt-joint regrowth (BJR) technique. A buried ridge waveguide structure is adopted for the AWG combiner. A self aligned fabrication procedure is adopted for the fabrication of the waveguide structure of the device to eliminate the misalignment between the laser active waveguide and the passive waveguide. A Ti thin film heater is integrated for each laser in the array. With the help of the heaters, ten laser emissions with 1.8 nm channel spacing are obtained. The integrated EAM has a larger than 11 dB static extinction ratios and larger than 8 GHz small signal modulation bandwidths. The light power collected in the output waveguide of the AWG is larger than -13 dBm for each wavelength.

  1. Results of a combined monolithic crystal and an array of ASICs controlled SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Conde, P.; González, A.J., E-mail: agonzalez@i3m.upv.es; Hernández, L.; Bellido, P.; Iborra, A.; Crespo, E.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Vidal, L.F.; Benlloch, J.M.

    2014-01-11

    In this work we present the energy and spatial resolutions we have obtained for a γ-ray detector based on a monolithic LYSO crystal coupled to an array of 256 SiPMs. Two crystal configurations of the same trapezoidal shape have been tried. In one approach all surfaces were black painted but the exit one facing the photosensor array which was polished. The other approach included a retroreflector (RR) layer coupled to the entrance face of the crystal powering the amount of transmitted light to the photosensors. Two coupling media between the scintillator and the SiPM array were used, namely direct coupling by means of optical grease and coupling through an array of light guides. Since the same operational voltage was supplied to the entire array, it was needed to equalize their gains before feeding their signals to the Data Acquisition system. Such a job was performed by means of 4 scalable Application Specific Circuits (ASICs). An energy resolution of about 24.4% has been achieved for the direct coupling with the RR layer together with a spatial resolution of approximately 2.9 mm at the detector center. With the light guides coupling the effects of image compression at the edges are significantly minimized, but worsening the energy resolution to about 33.1% with a spatial resolution nearing 4 mm at the detector center.

  2. Silica-based polypeptide-monolithic stationary phase for hydrophilic chromatography and chiral separation.

    Science.gov (United States)

    Zhao, Licong; Yang, Limin; Wang, Qiuquan

    2016-05-13

    Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition.

  3. Low Cost Phased Array Antenna System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — JEM Engineering proved the technical feasibility of the FlexScan array?a very low-cost, highly-efficient, wideband phased array antenna?in Phase I, and stands ready...

  4. Monolithically integrated heterodyne optical phase-lock loop with RF XOR phase detector.

    Science.gov (United States)

    Steed, Robert J; Pozzi, Francesca; Fice, Martyn J; Renaud, Cyril C; Rogers, David C; Lealman, Ian F; Moodie, David G; Cannard, Paul J; Lynch, Colm; Johnston, Lilianne; Robertson, Michael J; Cronin, Richard; Pavlovic, Leon; Naglic, Luka; Vidmar, Matjaz; Seeds, Alwyn J

    2011-10-10

    We present results for an heterodyne optical phase-lock loop (OPLL), monolithically integrated on InP with external phase detector and loop filter, which phase locks the integrated laser to an external source, for offset frequencies tuneable between 0.6 GHz and 6.1 GHz. The integrated semiconductor laser emits at 1553 nm with 1.1 MHz linewidth, while the external laser has a linewidth less than 150 kHz. To achieve high quality phase locking with lasers of these linewidths, the loop delay has been made less than 1.8 ns. Monolithic integration reduces the optical path delay between the laser and photodiode to less than 20 ps. The electronic part of the OPLL was implemented using a custom-designed feedback circuit with a propagation delay of ~1 ns and an open-loop bandwidth greater than 1 GHz. The heterodyne signal between the locked slave laser and master laser has phase noise below -90 dBc/Hz for frequency offsets greater than 20 kHz and a phase error variance in 10 GHz bandwidth of 0.04 rad2.

  5. Spectroscopic benzene detection using a broadband monolithic DFB-QCL array

    Science.gov (United States)

    Lewicki, Rafał; Witinski, Mark; Li, Biao; Wysocki, Gerard

    2016-03-01

    Quantitative laser spectroscopic measurements of complex molecules that have a broad absorption spectra require broadly tunable laser sources operating preferably in the mid-infrared molecular fingerprint region. In this paper a novel broadband mid-infrared laser source comprising of an array of single-mode distributed feedback quantum cascade lasers was used to target a broadband absorption feature of benzene (C6H6), a toxic and carcinogenic atmospheric pollutant. The DFB-QCL array is a monolithic semiconductor device with no opto-mechanical components, which eliminates issues with mechanical vibrations. The DFB-QCLs array used in this work provides spectral coverage from 1022.5 cm-1 to 1053.3 cm-1, which is sufficient to access the absorption feature of benzene at 1038 cm-1 (9.64 μm). A sensor prototype based on a 76 m multipass cell (AMAC-76LW, Aerodyne Research) and a dispersive DFB-QCL array beam combiner was developed and tested. The Allan deviation analysis of the retrieved benzene concentration data yields a short-term precision of 100 ppbv/Hz1/2 and a minimum detectable concentration of 12 ppbv for 200 s averaging time. The system was also tested by sampling atmospheric air as well as vapors of different chemical products that contained traces of benzene.

  6. Convective Interaction Media (CIM)--short layer monolithic chromatographic stationary phases.

    Science.gov (United States)

    Podgornik, Ales; Strancar, Ales

    2005-01-01

    Modern downstream processing requires fast and highly effective methods to obtain large quantities of highly pure substances. Commonly applied method for this purpose is chromatography. However, its main drawback is its throughput since purification, especially of large molecules, requires long process time. To overcome this problem several new stationary phases were introduced, among which short layer monoliths show superior properties for many applications. The purpose of this review is to give an overview about short methacrylate monolithic columns commercialised under the trademark Convective Interaction Media (CIM). Their unique properties are described from different perspectives, explaining reasons for their application on various areas. Approaches to prepare large volume methacrylate monolithic column are discussed and optimal solutions are given. Different examples of CIM monolithic column implementation are summarised in the last part of the article to give the reader an idea about their advantages.

  7. Monolithic electrically injected nanowire array edge-emitting laser on (001) silicon

    KAUST Repository

    Frost, Thomas

    2014-08-13

    A silicon-based laser, preferably electrically pumped, has long been a scientific and engineering goal. We demonstrate here, for the first time, an edge-emitting InGaN/GaN disk-in-nanowire array electrically pumped laser emitting in the green (λ = 533 nm) on (001) silicon substrate. The devices display excellent dc and dynamic characteristics with values of threshold current density, differential gain, T0 and small signal modulation bandwidth equal to 1.76 kA/cm2, 3 × 10-17 cm2, 232 K, and 5.8 GHz respectively under continuous wave operation. Preliminary reliability measurements indicate a lifetime of 7000 h. The emission wavelength can be tuned by varying the alloy composition in the quantum disks. The monolithic nanowire laser on (001)Si can therefore address wide-ranging applications such as solid state lighting, displays, plastic fiber communication, medical diagnostics, and silicon photonics. © 2014 American Chemical Society.

  8. Thiol-yne Click Adamantane Monolithic Stationary Phase for Capillary Electrochromatography

    Institute of Scientific and Technical Information of China (English)

    Dao, Thi Thu Hien; Guerrouache, Mohamed; Carbonnier, Benjamin

    2012-01-01

    A porous crosslinked organic polymer based on N-acryloxysuccinimide (NAS) and ethylene dimethacrylate (EDMA) was prepared inside 75 μm i.d. fused silica capillary as functionalizable monolithic stationary phase for electrochromatographic applications. Succinimide groups on the monolith surface provide reactive sites able to re- act readily through standard electrophile-nucleophile chemistry. Propargylamine was used to prepare alkyne func- tionalized poly(NAS-co-EDMA). Onto this thiol-reactive polymer surface was grafted adamantane units via a photochemically-driven addition reaction. Chemical characterization was performed in situ after each synthetic step by means of Raman spectroscopy and grafting kinetics was investigated to ensure quantitative grafting of 1-adamantanethiol. The as-designed monolithic stationary phase exhibited typical reversed-phase separation mechanism as evidenced by the linear increase of the logarithm of retention factor of neutral aromatic solutes with the increase of the aqueous buffer content in the mobile phase.

  9. Monolithic stationary phases with incorporated fumed silica nanoparticles. Part II. Polymethacrylate-based monolithic column with "covalently" incorporated modified octadecyl fumed silica nanoparticles for reversed-phase chromatography.

    Science.gov (United States)

    Aydoğan, Cemil; El Rassi, Ziad

    2016-05-01

    This study is concerned with the incorporation of surface modified fumed silica nanoparticles (FSNPs) into polymethacrylate based monolithic columns for use in reversed phase chromatography (RPC) of small solutes and proteins. First, FSNPs were modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) to yield the "hybrid" methacryloyl fumed silica nanoparticle (MFSNP) monomer. The resulting MFSNP was then mixed with glyceryl monomethacrylate (GMM) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent composed of cyclohexanol and dodecanol, and the in situ copolymerization of MFSNP, GMM and EDMA was performed in a stainless steel column of 4.6 mm i.d. The silanol groups of the hybrid monolith thus obtained were grafted with octadecyl ligands by perfusing the hybrid monolithic column with a solution of 4% w/v of dimethyloctadecylchlorosilane (DODCS) in toluene while the column was maintained at 110°C for 6h (in a heated HPLC oven). One of the originalities of this study was to demonstrate MFSNP as a novel derivatized "hybrid monomer" in making RPC monolithic columns with surface bound octadecyl ligands. In this respect, the RPC behavior of the monolithic column with "covalently" incorporated FNSPs having surface grafted octadecyl ligands was evaluated with alkylbenzenes, aniline derivatives and phenolic compounds. The results showed that the hybrid poly(GMA-EDMA-MFSNP) having surface bound octadecyl ligands exhibited hydrophobic interactions under reversed phase elution conditions. Furthermore, six standard proteins were baseline separated on the column using a 10min linear gradient elution at increasing ACN concentration in the mobile phase at a flow rate of 1.0mL/min using a 10 cm×4.6mm i.d. column. The relative standard deviations (RSDs) for the retention times of the tested solutes were lower than 2.1% and 2.4% under isocratic elution and gradient elution conditions, respectively.

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

    Science.gov (United States)

    Gurun, Gokce; Hasler, Paul; Degertekin, F

    2011-08-01

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

  11. Facile synthesis of gradient mesoporous carbon monolith based on polymerization-induced phase separation

    Science.gov (United States)

    Xu, Shunjian; Luo, Yufeng; Zhong, Wei; Xiao, Zonghu; Luo, Yongping; Ou, Hui; Zhao, Xing-Zhong

    2014-06-01

    In this paper, a gradient mesoporous carbon (GMC) monolith derived from the mixtures of phenolic resin (PF) and ethylene glycol (EG) was prepared by a facile route based on polymerization-induced phase separation under temperature gradient (TG). A graded biphasic structure of PF-rich and EG-rich phases was first formed in preform under a TG, and then the preform was pyrolyzed to obtain the GMC monolith. The TG is mainly induced by the thermal resistance of the preferential phase separation layer at high temperature region. The pore structure of the monolith changes gradually along the TG direction. When the TG varies from 58°C to 29°C, the pore size, apparent porosity and specific surface area of the monolith range respectively from 18 nm to 83 nm, from 32% to 39% and from 140.5 m2/g to 515.3 m2/g. The gradient porous structure of the monolith is inherited from that of the preform, which depends on phase separation under TG in the resin mixtures. The pyrolysis mainly brings about the contraction of the pore size and wall thickness as well as the transformation of polymerized PF into glassy carbon.

  12. Simulations of astronomical imaging phased arrays.

    Science.gov (United States)

    Saklatvala, George; Withington, Stafford; Hobson, Michael P

    2008-04-01

    We describe a theoretical procedure for analyzing astronomical phased arrays with overlapping beams and apply the procedure to simulate a simple example. We demonstrate the effect of overlapping beams on the number of degrees of freedom of the array and on the ability of the array to recover a source. We show that the best images are obtained using overlapping beams, contrary to common practice, and show how the dynamic range of a phased array directly affects the image quality.

  13. Delamination Detection Using Guided Wave Phased Arrays

    Science.gov (United States)

    Tian, Zhenhua; Yu, Lingyu; Leckey, Cara

    2016-01-01

    This paper presents a method for detecting multiple delaminations in composite laminates using non-contact phased arrays. The phased arrays are implemented with a non-contact scanning laser Doppler vibrometer (SLDV). The array imaging algorithm is performed in the frequency domain where both the guided wave dispersion effect and direction dependent wave properties are considered. By using the non-contact SLDV array with a frequency domain imaging algorithm, an intensity image of the composite plate can be generated for delamination detection. For the proof of concept, a laboratory test is performed using a non-contact phased array to detect two delaminations (created through quasi-static impact test) at different locations in a composite plate. Using the non-contact phased array and frequency domain imaging, the two impact-induced delaminations are successfully detected. This study shows that the non-contact phased array method is a potentially effective method for rapid delamination inspection in large composite structures.

  14. A novel, SiPM-array-based, monolithic scintillator detector for PET.

    Science.gov (United States)

    Schaart, Dennis R; van Dam, Herman T; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Beekman, Freek J

    2009-06-07

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce(3+) crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an approximately 0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 degrees , demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF(2) detector, equals 960 ps FWHM.

  15. A novel, SiPM-array-based, monolithic scintillator detector for PET

    Energy Technology Data Exchange (ETDEWEB)

    Schaart, Dennis R; Dam, Herman T van; Seifert, Stefan; Beekman, Freek J [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Vinke, Ruud; Dendooven, Peter; Loehner, Herbert [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA, Groningen (Netherlands)], E-mail: d.r.schaart@tudelft.nl

    2009-06-07

    Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce{sup 3+} crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an {approx}0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 deg., demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF{sub 2} detector, equals 960 ps FWHM.

  16. Flexible Ultrasonic Phased-Array Probe

    Institute of Scientific and Technical Information of China (English)

    施克仁; 阙开良; 郭大勇

    2004-01-01

    In ultrasonic phased-array testing, most probes are rigid with fixed elements. However, when testing a cambered piece, a rigid probe cannot be used directly, but an ultrasonic chock or coupling media must be used, which adds cost and reduces the accuracy. The objective of this research was to improve the tests of cambered pieces. A flexible ultrasonic phased-array probe was developed to do the flexible phased-array testing. The key technologies in the flexible phased-array probe include the probe design and the phased-array control. A new method was developed to design the flexible probe according to the curvature of the piece and the test depth. The method includes the calculation of the element's height (he), the relative rotation angle ((e), the distance between the adjoining elements (de), and the element's effective testing range. A flexible ultrasonic phased-array probe has been developed using this method.

  17. Fabrication of Porous Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate Monoliths via Thermally Induced Phase Separation

    Directory of Open Access Journals (Sweden)

    Takashi Tsujimoto

    2016-02-01

    Full Text Available This study deals with the fabrication of biodegradable porous materials from bacterial polyester, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB3HHx, via thermally induced phase separation. P3HB3HHx monoliths with topological porous structure were prepared by dissolution of P3HB3HHx in dimethyl sulfoxide (DMSO at 85 °C and subsequent quenching. The microstructure of the resulting P3HB3HHx monoliths was changed by the P3HB3HHx concentration of the polymer solution. Differential scanning calorimetry and polarized optical microscope analysis revealed that the P3HB3HHx monoliths crystallized during phase separation and the subsequent aging. The mechanical properties, such as compression modulus and stress, of the monoliths depended on the 3-hydroxyhexanoate content of P3HB3HHx. Furthermore, the P3HB3HHx monolith absorbed linseed oil in preference to water in a plant oil–water mixture. In combination with the biodegradable character of P3HB3HHx, the present study is expected to contribute to the development of bio-based materials.

  18. Monolithic, High-Speed Fiber-Optic Switching Array for Lidar

    Science.gov (United States)

    Suckow, Will; Roberts, Tony; Switzer, Gregg; Terwilliger, Chelle

    2011-01-01

    Current fiber switch technologies use mechanical means to redirect light beams, resulting in slow switch time, as well as poor reliability due to moving parts wearing out quickly at high speeds. A non-mechanical ability to switch laser output into one of multiple fibers within a fiber array can provide significant power, weight, and costs savings to an all-fiber system. This invention uses an array of crystals that act as miniature prisms to redirect light as an electric voltage changes the prism s properties. At the heart of the electro-optic fiber-optic switch is an electro- optic crystal patterned with tiny prisms that can deflect the beam from the input fiber into any one of the receiving fibers arranged in a linear array when a voltage is applied across the crystal. Prism boundaries are defined by a net dipole moment in the crystal lattice that has been poled opposite to the surrounding lattice fabricated using patterned, removable microelectrodes. When a voltage is applied across the crystal, the resulting electric field changes the index of refraction within the prism boundaries relative to the surrounding substrate, causing light to deflect slightly according to Snell s Law. There are several materials that can host the necessary monolithic poled pattern (including, but not limited to, SLT, KTP, LiNbO3, and Mg:LiNbO3). Be cause this is a solid-state system without moving parts, it is very fast, and does not wear down easily. This invention is applicable to all fiber networks, as well as industries that use such networks. The unit comes in a compact package, can handle both low and high voltages, and has a high reliability (100,000 hours without maintenance).

  19. Design and fabrication of multi-channel photodetector array monolithic with arrayed waveguide grating

    Science.gov (United States)

    Qian-Qian, Lv; Pan, Pan; Han, Ye; Dong-Dong, Yin; Yu-Bing, Wang; Xiao-Hong, Yang; Qin, Han

    2016-03-01

    We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13-channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refractive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickness of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick matching layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W. Project supported by the National High Technology Research and Development Program of China (Grant Nos. 2013AA031401, 2015AA016902, and 2015AA016904), the National Natural Science Foundation of China (Grant Nos. 61176053, 61274069, and 61435002), and the National Basic Research Program of China (Grant Nos. 2012CB933503 and 2013CB932904).

  20. Study of stacked microstrip phased arrays

    Science.gov (United States)

    Arts, M. J.; Smolders, A. B.

    1993-06-01

    Two theoretical methods for studying stacked-patch microstrip phased arrays are compared: (1) the element-by-element approach (finite array approach) of Pozar (1986) and Smolders (1992); and (2) the infinite approach of Pozar and Shaubert (1984) and Liu et al. (1988). Both theories were found to give almost the same results for a 7 x 7 stacked microstrip antenna, except for edge array elements and for large scan angles. Edge array elements could only be analyzed properly by using a finite array approach. Coupling measurements were made on a 7 x 7 array with a single patch layer, and the results agreed well with calculations.

  1. Antennas for Frequency Reconfigurable Phased Arrays

    NARCIS (Netherlands)

    Haider, S.N.

    2015-01-01

    Sensors such as phased array radars play a crucial role in public safety. They are unavoidable for surveillance, threat identification and post-disaster management. However, different scenarios impose immensely diverse requirements for these systems. Phased array systems occupy a large space. In add

  2. Quantitative ultrasonic phased array imaging

    Science.gov (United States)

    Engle, Brady J.; Schmerr, Lester W., Jr.; Sedov, Alexander

    2014-02-01

    When imaging with ultrasonic phased arrays, what do we actually image? What quantitative information is contained in the image? Ad-hoc delay-and-sum methods such as the synthetic aperture focusing technique (SAFT) and the total focusing method (TFM) fail to answer these questions. We have shown that a new quantitative approach allows the formation of flaw images by explicitly inverting the Thompson-Gray measurement model. To examine the above questions, we have set up a software simulation test bed that considers a 2-D scalar scattering problem of a cylindrical inclusion with the method of separation of variables. It is shown that in SAFT types of imaging the only part of the flaw properly imaged is the front surface specular response of the flaw. Other responses (back surface reflections, creeping waves, etc.) are improperly imaged and form artifacts in the image. In the case of TFM-like imaging the quantity being properly imaged is an angular integration of the front surface reflectivity. The other, improperly imaged responses are also averaged, leading to a reduction in some of the artifacts present. Our results have strong implications for flaw sizing and flaw characterization with delay-and-sum images.

  3. Large phased-array radars

    Science.gov (United States)

    Brookner, Eli, Dr.

    1988-12-01

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  4. A new monolithic approach for mid-IR focal plane arrays

    Science.gov (United States)

    Xie, Chengzhi; Pusino, Vincenzo; Khalid, Ata; Aziz, Mohsin; Steer, Matthew J.; Cumming, David R. S.

    2016-10-01

    Antimonide-based photodetectors have recently been grown on a GaAs substrate by molecular beam epitaxy (MBE) and reported to have comparable performance to the devices grown on more expensive InSb and GaSb substrates. We demonstrated that GaAs, in addition to providing a cost saving substrate for antimonide-based semiconductor growth, can be used as a functional material to fabricate transistors and realize addressing circuits for the heterogeneously grown photodetectors. Based on co-integration of a GaAs MESFET with an InSb photodiode, we recently reported the first demonstration of a switchable and mid-IR sensible photo-pixel on a GaAs substrate that is suitable for large-scale integration into a focal plane array. In this work we report on the fabrication steps that we had to develop to deliver the integrated photo-pixel. Various highly controllable etch processes, both wet and dry etch based, were established for distinct material layers. Moreover, in order to avoid thermally-induced damage to the InSb detectors, a low temperature annealed Ohmic contact was used, and the processing temperature never exceeded 180 °C. Furthermore, since there is a considerable etch step (> 6 μm) that metal must straddle in order to interconnect the fabricated devices, we developed an intermediate step using polyimide to provide a smoothing section between the lower MESFET and upper photodiode regions of the device. This heterogeneous technology creates great potential to realize a new type of monolithic focal plane array of addressable pixels for imaging in the medium wavelength infrared range without the need for flip-chip bonding to a CMOS readout chip.

  5. Chip-based molecularly imprinted monolithic capillary array columns coated GO/SiO2 for selective extraction and sensitive determination of rhodamine B in chili powder.

    Science.gov (United States)

    Zhai, Haiyun; Huang, Lu; Chen, Zuanguang; Su, Zihao; Yuan, Kaisong; Liang, Guohuan; Pan, Yufang

    2017-01-01

    A novel solid-phase extraction chip embedded with array columns of molecularly imprinted polymer-coated silanized graphene oxide (GO/SiO2-MISPE) was established to detect trace rhodamine B (RB) in chili powder. GO/SiO2-MISPE monolithic columns for RB detection were prepared by optimizing the supporting substrate, template, and polymerizing monomer under mild water bath conditions. Adsorption capacity and specificity, which are critical properties for the application of the GO/SiO2-MISPE monolithic column, were investigated. GO/SiO2-MIP was examined by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy. The recovery and the intraday and interday relative standard deviations for RB ranged from 83.7% to 88.4% and 2.5% to 4.0% and the enrichment factors were higher than 110-fold. The chip-based array columns effectively eliminated impurities in chili powder, indicating that the chip-based GO/SiO2-MISPE method was reliable for RB detection in food samples using high-performance liquid chromatography. Accordingly, this method has direct applications for monitoring potentially harmful dyes in processed food.

  6. Airborne Electronically Steerable Phased Array (AESPA) program

    Science.gov (United States)

    1979-01-01

    The basic concept and design of a flatplate-fed transmission array are described and system performance requirements are summarized. Particular emphasis is given to the design of the aperture, the radiating element, the phase shifter, the flatplate feed, and the mechanical support structure. Fabrication and testing techniques are considered. Of the three major parameters of interest in demonstrating the performance capabilities of the transmissive array, beamwidth was shown to be the least sensitive to system amplitude and phase errors. Beam pointing angle was also shown to be relatively insensitive to errors. Close agreement between measured and calculated values was found for array gain. The greatest difference was found for array sidelone level.

  7. Monolithic millimeter-wave diode array beam controllers: Theory and experiment

    Science.gov (United States)

    Sjogren, L. B.; Liu, H.-X. L.; Wang, F.; Liu, T.; Wu, W.; Qin, X.-H.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.; Maserjian, J.

    1992-01-01

    In the current work, multi-function beam control arrays have been fabricated and have successfully demonstrated amplitude control of transmitted beams in the W and D bands (75-170 GHz). While these arrays are designed to provide beam control under DC bias operation, new designs for high-speed electronic and optical control are under development. These arrays will fill a need for high-speed watt-level beam switches in pulsed reflectometer systems under development for magnetic fusion plasma diagnostics. A second experimental accomplishment of the current work is the demonstration in the 100-170 GHz (D band) frequency range of a new technique for the measurement of the transmission phase as well as amplitude. Transmission data can serve as a means to extract ('de-embed') the grid parameters; phase information provides more complete data to assist in this process. Additional functions of the array beam controller yet to be tested include electronically controlled steering and focusing of a reflected beam. These have application in the areas of millimeter-wave electronic scanning radar and reflectometry, respectively.

  8. Development of a monolithic polymer pipette for solid-phase extraction of liquiritigenin in rat plasma

    Institute of Scientific and Technical Information of China (English)

    Hong Wu Zhang; Kang Li; Zhi Xian Liang; Feng Yang Wang; Qi Wen Lu

    2012-01-01

    A monolithic polymer column with mixed-mode interaction was prepared by in situ polymerization in a 1000 μ,L pipette.Two kinds of monomers,butyl methacrylate (BMA) and 2-(dimethylamino)ethyl methacrylate (DMAM) were applied to constructing the mixed-mode interaction of monolithic polymer column.Its solid-phase extraction properties for liquiritigenin (LQG) were evaluated by high performance liquid chromatography (HPLC) with a gradient elution procedure.After the extraction procedure was optimized,the maximum binding capacity and extraction recovery following the optimal extraction procedure were investigated.Calibration curve was expressed as A =65.9C + 4.53 (r2 =0.998) with a linear range of 0.151-1.80 μg/mL.The experimental results indicate that the monolithic polymer pipette presents good extraction efficiency for LQG.It can be envisaged that the developed monolithic polymer pipette possesses the potential for its application to the enrichment of other flavonoids compounds being siniilar to the structure of LQG.

  9. Monolithic stationary phases with incorporated fumed silica nanoparticles. Part I. Polymethacrylate-based monolithic column with incorporated bare fumed silica nanoparticles for hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Aydoğan, Cemil; El Rassi, Ziad

    2016-05-01

    Fumed silica nanoparticles (FSNPs), were incorporated for the first time into a polymethacrylate monolithic column containing glyceryl monomethacrylate (GMM) and ethylene dimethacrylate (EDMA) in order to develop a new monolithic column for hydrophilic interaction high performance liquid chromatography (HILIC). When compared to poly(GMM-EDMA) monolithic column without FSNPs, the same monolithic column with incorporated FSNPs yielded important effects on HILIC separations. The effects of monomers and FSNPs content of the polymerization mixture on the performance of the monolithic column were examined in details, and the optimized stationary phase was investigated over a wide range of mobile phase composition with polar acidic, weakly basic and neutral analytes including hydroxy benzoic acids, nucleotides, nucleosides, dimethylformamide, formamide and thiourea. The retention of these analytes was mainly controlled by hydrophilic interactions with the FSNPs and electrostatic repulsion from the negatively charged silica surface in the case of hydroxy benzoic acids and nucleotides. The electrostatic repulsion was minimized by decreasing the pH of the aqueous component of the mobile phase, which in turn enhanced the retention of acidic solutes. Nucleotides were best separated using step gradient elution at decreasing pH as well as ACN concentration in the mobile phase. Improved peak shape and faster analysis of nucleosides were attained by a fast linear gradient elution with a shallow decrease in the ACN content of the ACN-rich mobile phase. The run-to-run and column-to-column reproducibility were satisfactory. The percent relative standard deviations (%RSDs) for the retention times of tested solutes were lower than 2.5% under isocratic conditions and lower than 3.5 under gradient conditions.

  10. Low Cost Phased Array Antenna System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A program is proposed to research the applicability of a unique phased array technology, dubbed FlexScan, to S-band and Ku-band communications links between...

  11. Redundancy Calibration of Phased Array Stations

    CERN Document Server

    Noorishad, Parisa; van Ardenne, Arnold; van der Hulst, Thijs

    2012-01-01

    Our aim is to assess the benefits and limitations of using the redundant visibility information in regular phased array systems for improving the calibration. Regular arrays offer the possibility to use redundant visibility information to constrain the calibration of the array independent of a sky model and a beam models of the station elements. It requires a regular arrangement in the configuration of array elements and identical beam patterns. We revised a calibration method for phased array stations using the redundant visibility information in the system and applied it successfully to a LOFAR station. The performance and limitations of the method were demonstrated by comparing its use on real and simulated data. The main limitation is the mutual coupling between the station elements, which leads to non-identical beams and stronger baseline dependent noise. Comparing the variance of the estimated complex gains with the Cramer-Rao Bound (CRB) indicates that redundancy is a stable and optimum method for cali...

  12. Nonlinear Ultrasonic Phased Array Imaging

    Science.gov (United States)

    Potter, J. N.; Croxford, A. J.; Wilcox, P. D.

    2014-10-01

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

  13. Nonlinear ultrasonic phased array imaging

    OpenAIRE

    Potter, J N; Croxford, A.J.; Wilcox, P. D.

    2014-01-01

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging t...

  14. Nonlinear ultrasonic phased array imaging.

    Science.gov (United States)

    Potter, J N; Croxford, A J; Wilcox, P D

    2014-10-03

    This Letter reports a technique for the imaging of acoustic nonlinearity. By contrasting the energy of the diffuse field produced through the focusing of an ultrasonic array by delayed parallel element transmission with that produced by postprocessing of sequential transmission data, acoustic nonlinearity local to the focal point is measured. Spatially isolated wave distortion is inferred without requiring interrogation of the wave at the inspection point, thereby allowing nonlinear imaging through depth.

  15. Ferrite LTCC based phased array antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

  16. Microchip free flow planar reversed phase electrochromatography with monolithic stationary phase.

    Science.gov (United States)

    Wang, Pingli; Tao, Dingyin; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2009-08-01

    In this study, microchip free flow planar RP electrochromatography (microFF-PRPEC) was developed by in situ polymerization of monolithic materials in microchamber, and successfully applied for the separation of dyes and proteins. Poly(butyle methyacrylate-co-ethylene dimethacrylate) was prepared by UV-initiated polymerization in a glass microchamber (42 mm long, 23 mm wide, and 28 microm deep). A mixture of 1-propanol, 1,4-butanediol, and water was chosen as porogens, and 1.2% (wt%) 2-acrylamide-2-methyl-propanesulfonic acid (AMPS) was added into the polymerization solution to generate EOF. With 30% v/v ACN-15 mM Tris-HCl as the mobile phase, rhodamine B and methyl green were separated from each other with 400 V transverse voltage applied, and resolution as high as 4.6 was obtained, much higher than that obtained by microFFE under optimal conditions. Furthermore, microFF-PRPEC was also successfully applied into the separation of lysozyme and ribonuclease B, and resolution as high as 9.4 was obtained. All these results demonstrate that microFF-RPPEC might have great potential in the microscale continuous preparation of samples with improved resolution compared to microFFE.

  17. Monolithic GaAs Dual-Gate FET Phase Shifter.

    Science.gov (United States)

    1982-02-01

    and P. Hats-op. "Dual-gae MESPET phase stutter with gainappioodwsel the43*phas alltif (Fi. 6. Net apliier is atl 12 Hz." Elcron. Lett.. vol. 16. O.14...Park Redondo Beach, CA 90278 Watkins -Johnson Co. 1 E. J. Crescenzi, Jr./ Professor L. Eastman 1 K. Niclas Phillips Hall 3333 Hillview Ave. Cornell

  18. Probe suppression in conformal phased array

    CERN Document Server

    Singh, Hema; Neethu, P S

    2017-01-01

    This book considers a cylindrical phased array with microstrip patch antenna elements and half-wavelength dipole antenna elements. The effect of platform and mutual coupling effect is included in the analysis. The non-planar geometry is tackled by using Euler's transformation towards the calculation of array manifold. Results are presented for both conducting and dielectric cylinder. The optimal weights obtained are used to generate adapted pattern according to a given signal scenario. It is shown that array along with adaptive algorithm is able to cater to an arbitrary signal environment even when the platform effect and mutual coupling is taken into account. This book provides a step-by-step approach for analyzing the probe suppression in non-planar geometry. Its detailed illustrations and analysis will be a useful text for graduate and research students, scientists and engineers working in the area of phased arrays, low-observables and stealth technology.

  19. Phase Noise in Photonic Phased-Array Antenna Systems

    Science.gov (United States)

    Logan, Ronald T., Jr.; Maleki, Lute

    1998-01-01

    The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.

  20. Monolithic LaBr₃:Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography.

    Science.gov (United States)

    Seifert, Stefan; van Dam, Herman T; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R

    2012-04-21

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high γ-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal arrays. Here, we present the characterization of a detector consisting of a 18.0 mm×16.2 mm×10.0 mm monolithic LaBr₃:5%Ce scintillator directly coupled to a 4×4 array of silicon photomultipliers. An energy resolution of 6.4% full-width-at-half-maximum (FWHM) was obtained. The point-spread-function (PSF) was determined for different regions of the detector. The full-width-at-half-maximum (FWHM) of the PSF was measured to be <1.5 mm at the center of the detector and <1.7 mm averaged over the entire crystal. Both values are not corrected for the ~0.6 mm FWHM test beam diameter. Furthermore, the influence of edge effects was investigated. We found that near the edges of the detector the spatial resolution degrades to 2.2 mm (FWHM), and a bias in the position estimates, up to 1.5 mm, was observed. Moreover, the coincidence resolving time for two identical detectors in coincidence was measured to be as small as ~198 ps FWHM.

  1. Monolithic Multi-Colour 40 GHz Mode-Locked Laser Array

    OpenAIRE

    Hou, Lianping; Eddie, Iain; Marsh, John

    2016-01-01

    The monolithic integration of four 40 GHz multi-colored mode-locked lasers with a 4×1 MMI, four electroabsorption modulators and an SOA has been demonstrated. The shortest pulse widths are between 2.63 and 2.85 ps.

  2. Pressure vessel inspections using ultrasonic phased arrays

    Energy Technology Data Exchange (ETDEWEB)

    Moles, M.D.C. [R/D Tech Toronto, Toronto, ON (Canada); Jacques, F.; Dube, N. [R/D Tech Quebec PQ (Canada)

    2003-07-01

    Pressure vessels are used in several industries, including the petrochemical and petroleum industries. Welds in the pressure vessels often produce defects which propagate and fail with time. Many types of pressure vessel weld inspections can now be conducted using automated ultrasonics which offers several advantages over radiography. In terms of phased arrays, custom tailored time-of-flight diffraction (TOFD) and ASME code Section V raster scans, can successfully perform high speed inspections with minimal operator subjectivity. The phased array beams can be steered, scanned, swept and focused electronically. Beam steering can be used to map welds at appropriate angles to optimize probability of defect detection. The main challenge lies with the initial equipment cost, technology awareness, and availability of trained operators. Phased arrays offer great flexibility for different components, defect detection and tailored imaging. 8 refs., 10 figs.

  3. Mathematical Simulating Model of Phased-Array Antenna in Multifunction Array Radar

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A mathematical simulating model of phased-array antenna in multifunction array radar has been approached in this paper, including the mathematical simulating model of plane phased-array pattern, the mathematical simulating model of directionality factor, the mathematical simulating model of array factor, the mathematical simulating model of array element factor and the mathematical simulating model of beam steering.

  4. Ka-Band Phased Array System Characterization

    Science.gov (United States)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  5. Monolithic watt-level millimeter-wave diode-grid frequency tripler array

    Science.gov (United States)

    Hwu, R. J.; Luhmann, N. C., Jr.; Rutledge, D. B.; Hancock, B.; Lieneweg, U.

    1988-01-01

    In order to provide watt-level CW output power throughout the millimeter and submillimeter wave region, thousands of solid-state diodes have been monolithically integrated using a metal grid to produce a highly efficient frequency multiplier. Devices considered include GaAs Schottky diodes, thin MOS diodes, and GaAs Barrier-Intrinsic-N(+)diodes. The performance of the present compact low-cost device has been theoretically and experimentally validated.

  6. Synthesis of Phased Cylindrical Arc Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Hussein Rammal

    2009-01-01

    Full Text Available This paper describes a new approach to synthesize cylindrical antenna arrays controlled by the phase excitation, to synthesize directive lobe and multilobe patterns with steered zero. The proposed method is based on iterative minimization of a function that incorporates constraints imposed in each direction. An 8-element cylindrical antenna has been simulated and tested for various types of beam configurations.

  7. Ultrasonic fingerprinting by phased array transducer

    Science.gov (United States)

    Sednev, D.; Kataeva, O.; Abramets, V.; Pushenko, P.; Tverdokhlebova, T.

    2016-06-01

    Increasing quantity of spent nuclear fuel that must be under national and international control requires a novel approach to safeguard techniques and equipment. One of the proposed approaches is utilize intrinsic features of casks with spent fuel. In this article an application of a phased array ultrasonic method is considered. This study describes an experimental results on ultrasonic fingerprinting of austenitic steel seam weld.

  8. Ultrasonic fingerprinting by phased array transducer

    OpenAIRE

    Sednev, Dmitry Andreevich; Kataeva, O.; Abramets, V.; Pushenko, P.; Tverdokhlebova, T.

    2016-01-01

    Increasing quantity of spent nuclear fuel that must be under national and international control requires a novel approach to safeguard techniques and equipment. One of the proposed approaches is utilize intrinsic features of casks with spent fuel. In this article an application of a phased array ultrasonic method is considered. This study describes an experimental results on ultrasonic fingerprinting of austenitic steel seam weld.

  9. Phased array based ultrasound scanning system development

    Science.gov (United States)

    Sagdiev, R. K.; Denisov, E. S.; Evdokimov, Yu K.; Fazlyyyakhmatov, M. G.; Kashapov, N. F.

    2014-12-01

    Multichannel ultrasound scanning system based on phased arrays development is presented in this paper. Substantiation of system parameters is presented. The description of block diagram and hardware development is presented. The combination of the self-developed receiving and a transmitting units and commercially available FPGA unit and Personal Computer can solve our scientific goals, while providing a relatively low device cost.

  10. Phase calibration scheme for a ``T'' array

    Science.gov (United States)

    Ramesh, R.; Subramanian, K. R.; Sastry, Ch. V.

    1999-10-01

    A calibration scheme based on closure and redundancy techniques is described for correcting the phase errors in the complex visibilities observed with a T-shaped radio interferometer array. Practical details of the scheme are illustrated with reference to the Gauribidanur radioheliograph (GRH).

  11. Future of phased array radar systems

    Science.gov (United States)

    Bassyouni, Ahmed

    2011-12-01

    This paper spots the light on the future progress of phased array radar systems, presenting two innovative examples on the directions of development. The first example starts with the classic radar range equation to develop the topology of what is called a "Mobile Adaptive Digital Array Radar" (MADAR) system. The second example discusses the possibility to achieve what is called "Entangled Photonic Radar" (EPR) system. The EPR quantum range equation is derived and compared to the classic one to compare the performance. Block diagrams and analysis for both proposed systems are presented.

  12. Miniature Sensor Node with Conformal Phased Array

    Directory of Open Access Journals (Sweden)

    W. De Raedt

    2011-12-01

    Full Text Available This paper reports on the design and fabrication of a fully integrated antenna beam steering concept for wireless sensor nodes. The conformal array circumcises four cube faces with a silicon core mounted on each face. Every silicon core represents a 2 by 1 antenna array with an antenna element consisting of a dipole antenna, a balun, and a distributed MEMS phase shifter. All these components are based on a single wafer process and designed to work at 17.2 GHz. Simulations of the entire system and first results of individual devices are reported.

  13. A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications

    KAUST Repository

    Ghaffar, Farhan A.

    2015-06-01

    The theory and design of a half-mode substrate-integrated waveguide ferrite low-temperature cofired ceramic-based phase shifter are presented in this paper. Unlike typical ferrite-based designs, the biasing is done through embedded windings in a multi-layer substrate that not only obviates the requirement of bulky electromagnets, but also prevents loss of bias fields at the air-to-ferrite interface. The phase shifter is operated in the partially magnetized state of ferrite substrate. Through the combined effect of embedded windings, half-mode waveguide operation, and partially magnetized state, the required bias fields have been reduced by 90% as compared with conventional ferrite-based designs employing electromagnets. A complete analytical model, backed up by electromagnetic simulations and measured results from a prototype, is presented in this paper. The fabricated prototype demonstrates a phase shift of 83.2° at a center frequency of 13.1 GHz and a figure of merit of 83.2°/dB. As a proof-of-concept, the proposed phase shifter design is monolithically integrated with a two-element antenna array to demonstrate a measured beam steering of 30°. The phase shifter design is highly efficient in terms of required bias fields, and it has a small form factor and can be easily integrated with other electronic components and systems. © 1965-2012 IEEE.

  14. A 1.55-μm laser array monolithically integrated with an MMI combiner

    Institute of Scientific and Technical Information of China (English)

    Ma Li; Zhu Hongliang; Liang Song; Wang Baojun; Zhang Can; Zhao Lingjuan; Bian Jing

    2013-01-01

    The monolithic integration of four 1.55-μm range InGaAsP/InP distributed feedback lasers with a 4 × 1multimode-interference (MMI) optical combiner using the varied width ridge method is proposed and demonstrated.The average output power is 1.5 mW when the current of LD is 100 mA and the threshold current is 30-35 mA at 25 ℃.The lasing wavelength is 1.55-μm range and 40 dB sidemode suppression ratio is obtained.The four channels can operate separately or simultaneously.

  15. A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

    Science.gov (United States)

    Ludewig, Ronny; Nietzsche, Sandor; Scriba, Gerhard K E

    2011-01-01

    A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations.

  16. PHASIM, an advanced phased array antenna software simulator

    NARCIS (Netherlands)

    Keizer, W.P.M.N.

    2000-01-01

    A sophisticated phased array simulator software package for the design and analysis of planar phased array antennas is presented. This package can accurately simulate the far-field characteristics of a large variety of planar phased array configurations in both the frequency and time domain. The sim

  17. On the Application of a Monolithic Array for Detecting Intensity-Correlated Photons Emitted by Different Source Types

    CERN Document Server

    Boiko, D L; Brauer, N; Sergio, M; Niclass, C; Beretta, G B; Charbon, E

    2009-01-01

    It is not widely appreciated that many subtleties are involved in the accurate measurement of intensity-correlated photons; even for the original experiments of Hanbury Brown and Twiss (HBT). Using a monolithic 4x4 array of single-photon avalanche diodes (SPADs), together with an off-chip algorithm for processing streaming data, we investigate the difficulties of measuring second-order photon correlations g2 in a wide variety of light fields that exhibit dramatically different correlation statistics: a multimode He-Ne laser, an incoherent intensity-modulated lamp-light source and a thermal light source. Our off-chip algorithm treats multiple photon-arrivals at pixel-array pairs, in any observation interval, with photon fluxes limited by detector saturation, in such a way that a correctly normalized g2 function is guaranteed. The impact of detector background correlations between SPAD pixels and afterpulsing effects on second-order coherence measurements is discussed. These results demonstrate that our monolit...

  18. An Optical Phased Array for LIDAR

    Science.gov (United States)

    Wang, Y.; Wu, M. C.

    2016-11-01

    We have previously demonstrated the development of an Optical Phased Array (OPA) micromechanical system (MEMS) used for beam steering, which shows great advantages over previous mechanisms such as opto-mechanical, acousto-optical (AO) or electro-optical (EO). We aim to integrate the OPA MEMS system into the application of automobile navigation, which is currently primarily dominated by opto-mechanical scanning based systems. Opto-mechanical scanning devices are usually bulky and relatively slow, while competing technologies (AO, EO) utilize devices that while small in size, cannot provide the steering speeds and versatility necessary for many applications. In drawing from phased array concepts that revolutionized RADAR technology by providing a compact, agile alternative to mechanically steered technology, the OPA based LIDAR program seeks to integrate thousands of closely packed optical emitting facets, precise relative electronic phase control of these facets, and all within a very small form factor. Comparing with other competing LIDAR system, the OPA based LIDAR system will have multiple degrees of freedom for phase control which enables not only agile beam steering but also beam forming and multiple beam generation, greatly expanding the diversity of applications.

  19. Development of monolith with a carbon-nanofiber-washcoat as a structured catalyst support in liquid phase

    NARCIS (Netherlands)

    Jarrah, Nabeel A.; Ommen, van J.G.; Lefferts, L.

    2003-01-01

    Washcoats with improved mass transfer properties are necessary to circumvent concentration gradients in case of fast reactions in liquid phase, e.g. nitrate hydrogenation. A highly porous, high surface area (180 m2/g) and thin washcoat of carbon fibers, was produced on a monolith support by methane

  20. Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

    2015-06-01

    An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography.

  1. Measured Aperture-Array Noise Temperature of the Mark II Phased Array Feed for ASKAP

    CERN Document Server

    Chippendale, A P; Beresford, R J; Hampson, G A; Shaw, R D; Hayman, D B; Macleod, A; Forsyth, A R; Hay, S G; Leach, M; Cantrall, C; Brothers, M L; Hotan, A W

    2015-01-01

    We have measured the aperture-array noise temperature of the first Mk. II phased array feed that CSIRO has built for the Australian Square Kilometre Array Pathfinder telescope. As an aperture array, the Mk. II phased array feed achieves a beam equivalent noise temperature less than 40 K from 0.78 GHz to 1.7 GHz and less than 50 K from 0.7 GHz to 1.8 GHz for a boresight beam directed at the zenith. We believe these are the lowest reported noise temperatures over these frequency ranges for ambient-temperature phased arrays. The measured noise temperature includes receiver electronics noise, ohmic losses in the array, and stray radiation from sidelobes illuminating the sky and ground away from the desired field of view. This phased array feed was designed for the Australian Square Kilometre Array Pathfinder to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array.

  2. Acoustic trapping with a high frequency linear phased array

    OpenAIRE

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

    2012-01-01

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

  3. Phased Antenna Array for Global Navigation Satellite System Signals

    Science.gov (United States)

    Turbiner, Dmitry (Inventor)

    2015-01-01

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

  4. Sol-gel synthesis of macroporous barium zirconate monoliths from ionic precursors via a phase separation route

    Science.gov (United States)

    Guo, Xingzhong; Wang, Zichen; Song, Jie; Yang, Hui

    2017-03-01

    Monolithic macroporous barium zirconate derived from ionic precursors has been successfully prepared via a phase separation route in the presence of poly(ethylene oxide) (PEO) and propyleneoxide (PO). Poly(ethylene oxide) (PEO) acts as a phase separation inducer, while propyleneoxide (PO) acts as a gelation accelerant in the sol-gel process. Appropriate choice of poly(ethylene oxide) (PEO) and propyleneoxide (PO) allows the production of continuous macroporous monolithic gel with a porosity of ca. 63% and a macropore size of 1.8 μm. Some BaCl2 recrystallizes in the dried gel, and subsequently tetragonal ZrO2 phase precipitates after heat-treated at 800 °C. The crystalline phase barium zirconate forms after heat treatment at 1100 °C in air, while the macroporous structure is preserved with a slight increase of porosity and a decrease of macropore size.

  5. Comparison of Stability-Indicating LC Methods Using Light Scattering and Photodiode Array Detection with Monolithic Column for Determination of Quinapril and Hydrochlorothiazide.

    Science.gov (United States)

    de Diego, Marta; Godoy, Ricardo; Mennickent, Sigrid; Vergara, Carola; Charnock, Henry; Hernández, Camilo

    2016-09-01

    Rapid stability-indicating LC methods for simultaneous analysis of quinapril and hydrochlorothiazide were developed, validated and compared using evaporative light scattering detection (ELSD) and diode array detection (DAD). For the separation of quinapril, hydrochlorothiazide and its major degradation products, a monolithic column was used and the analytes were eluted within 7 min, applying gradient mobile phase in both methods. Quinapril was subjected to hydrolytic, oxidative, thermal, humidity and photolytic stress conditions. Degradation products were well resolved from main peaks and from each other, proving the stability-indicating power of the methods. The response with DAD was linear and the response with ELSD was fitted to a power function, for quinapril and hydrochlorothiazide concentrations of 20-160 and 12.5-100 µg mL(-1), respectively. DAD method achieved better precision than ELSD method, the LOQ of DAD was lower and the accuracy of the methods was similar. Quinapril degrade by hydrolysis and thermal stress, showing the formation of quinaprilat and quinapril diketopiperazine as degradants, which were identified by MS-MS. The methods were successfully applied to quantify quinapril and hydrochlorothiazide in commercial tablets. LC-DAD and LC-ELSD methods are suitable to assess the stability and routine analysis of quinapril and hydrochlorothiazide in pharmaceutical industry.

  6. A monolithic K-band phase-locked loop for microwave radar application

    Science.gov (United States)

    Zhou, Guangyao; Ma, Shunli; Li, Ning; Ye, Fan; Ren, Junyan

    2017-02-01

    A monolithic K-band phase-locked loop (PLL) for microwave radar application is proposed and implemented in this paper. By eliminating the tail transistor and using optimized high-Q LC-tank, the proposed voltage-controlled oscillator (VCO) achieves a tuning range of 18.4 to 23.3 GHz and reduced phase noise. Two cascaded current-mode logic (CML) divide-by-two frequency prescalers are implemented to bridge the frequency gap, in which inductor peaking technique is used in the first stage to further boost allowable input frequency. Six-stage TSPC divider chain is used to provide programmable division ratio from 64 to 127, and a second-order passive loop filter with 825 kHz bandwidth is also integrated on-chip to minimize required external components. The proposed PLL needs only approximately 18.2 μs settling time, and achieves a wide tuning range from 18.4 to 23.3 GHz, with a typical output power of -0.84 dBm and phase noise of -91.92 dBc/Hz @ 1 MHz. The chip is implemented in TSMC 65 nm CMOS process, and occupies an area of 0.56 mm2 without pads under a 1.2 V single voltage supply. Project supported by the National High-Tech Research and Development Program of China (No. 2013AA014101).

  7. Acoustic trapping with a high frequency linear phased array.

    Science.gov (United States)

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

    2012-11-19

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

  8. MMIC devices for active phased array antennas

    Science.gov (United States)

    Mittra, R.

    1986-01-01

    The use of finlines for microwave monolithic integrated circuit application in the 20 to 40 GHz frequency range. Other wave guiding structures, are also examined from a comparative point of view and some sonclusions are drawn on the basis of the results.

  9. Hydrophobic polymer monoliths as novel phase separators: Application in continuous liquid-liquid extraction systems

    NARCIS (Netherlands)

    Peroni, D.; Vanhoutte, D.; Vilaplana, F.; Schoenmakers, P.; de Koning, S.; Janssen, H.-G.

    2012-01-01

    Hydrophobic macroporous polymer monoliths are shown to be interesting materials for the construction of "selective solvent gates". With the appropriate surface chemistry and porous properties the monoliths can be made permeable only for apolar organic solvents and not for water. Different poly(butyl

  10. Cobalt phosphide nanowall arrays supported on carbon cloth: an efficient monolithic non-noble-metal hydrogen evolution catalyst

    Science.gov (United States)

    Yang, Libin; Wang, Kunyang; Du, Gu; Zhu, Wenxin; Cui, Liang; Zhang, Chengxiao; Sun, Xuping; Asiri, Abdullah M.

    2016-11-01

    Hydrogen has been considered as an ideal energy carrier for replacing fossil fuels to mitigate global energy crises. Hydrolysis of sodium borohydride (NaBH4) is simple and effective for hydrogen production but needs active and durable catalysts to accelerate the kinetics. In this paper, we demonstrate that cobalt phosphide nanowall arrays supported on carbon cloth (CoP NAs/CC) efficiently catalyze the hydrolytic dehydrogenation of NaBH4 with an activation energy of 42.1 kJ mol-1 in alkaline media. These monolithic CoP NAs/CC show a maximum hydrogen generation rate of 5960 {{ml}} {{{\\min }}}-1 {{{{g}}}-1}({{CoP})} and are robust with superior durability and reusability. They are also excellent in activity and durability for electrochemical hydrogen evolution in 1.0 M KOH, with the need of an overpotential of only 80 mV to drive 10 mA cm-2. They offer us a promising low-cost hydrogen-generating catalyst for applications.

  11. Coincidence detection of spatially correlated photon pairs with a monolithic time-resolving detector array

    CERN Document Server

    Unternährer, Manuel; Gasparini, Leonardo; Stoppa, David; Stefanov, André

    2016-01-01

    We demonstrate coincidence measurements of spatially entangled photons by means of a novel type of multi-pixel based detection array. The adopted sensor is a fully digital 8$\\times$16 silicon photomultiplier array allowing not only photon counting but also per-pixel time stamping of the arrived photons with a resolution of 65 ps. Together with a frame rate of 500 kfps, this property exceeds the capabilities of conventional charge-coupled device cameras which have become of growing interest for the detection of transversely correlated photon pairs. The sensor is used to measure a second-order correlation function for various non-collinear configurations of entangled photons generated by spontaneous parametric down-conversion. The experimental results are compared to theory.

  12. Monolithic photovotaic PbS-on-Si infrared-sensor array

    Energy Technology Data Exchange (ETDEWEB)

    Masek, J.; Zogg, H.; Maissen, C.; Blunier, S. (Arbeitsgemeinschaft fur Industrielle Forschung, Swiss Federal Inst. of Tech., ETH-Honggerberg, CH-8093 Zurich (CH)); Ishida, A. (Shizuoka Univ., Hamamatsu (Japan). Faculty of Engineering)

    1990-01-01

    The authors have grown epitaxial narrow-gap PbS-on-Si substrates using a stacked CaF{sub 2}-BaF{sub 2} intermediate buffer layer, and have fabricated linear arrays of photovoltaic infrared (IR) sensors in the PbS layer for the first time. The sensors of the array exhibit resistance-area products at zero bias of 3{Omega}{center dot}cm{sup 2} at 200 K (3.4-{mu}m cutoff wavelength) and 2{center dot}10{sup 5} {Omega}{center dot}cm{sup 2} at 84 K (4-{mu}m cutoff), with corresponding detectivities of 2{center dot}10{sup 10} and 1{center dot}10{sup 13}cm{center dot}{radical}Hz/W, respectively.

  13. [Modeling and simulation of responses from ultrasonic linear phased array].

    Science.gov (United States)

    He, Wenjing; Zhu, Yuanzhong; Wang, Yufeng; He, Lingli; Lai, Siyu

    2012-10-01

    Phased array transducers are very attractive because the beam generated by the arrays can be electronically focused and steered. The present work characterizes far-field 2D properties of phased array system by functions that are deduced from rectangle source, rectangle line array and phased array based on point source. Results are presented for the distribution of ultrasound intensity on plane xoz and on x-axis by simulation using numerical calculation. It is shown that the shape of response of rectangle line array is modulated by the single array element. It is also demonstrated that the delay time of phased array is the key to steer the beam, sacrificing the value of main lobe and increasing the number of side lobes.

  14. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    Science.gov (United States)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-06-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  15. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    Science.gov (United States)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-01-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  16. Effective extraction of triazines from environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction.

    Science.gov (United States)

    Mei, Meng; Huang, Xiaojia; Yang, Xiaodong; Luo, Qing

    2016-09-21

    This article reports on the effective extraction of triazines from environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction (ME-MB/IT-SPME). Firstly, monolithic poly (octyl methacrylate-co-ethyleneglycol dimethacrylate) capillary column doped with magnetic nanoparticles was synthesized inside a fused silica. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field during adsorption and desorption steps. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample and desorption solvent, pH value and ionic strength in sample matrix on the performance of ME-MB/IT-SPME for triazines were investigated in details. Under the optimized conditions, the developed ME-MB/IT-SPME showed satisfactory quantitative extraction efficiencies of the target analytes between 64.8% and 99.7%. At the same time, the ME-MB/IT-SPME was combined with high-performance liquid chromatography with diode array detection to detect six triazines in water samples. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were in the ranges of 0.074-0.23 μg/L and 0.24-0.68 μg/L, respectively. The precision of the proposed method was evaluated in terms of intra- and inter-assay variability calculated as relative standard deviation, and it was found that the values were all below 10%. Finally, the developed method was successfully applied for environmental water samples such as farmland, lake and river water with spiked recoveries in the range of 70.7-119%.

  17. Effects of pressure and frictional heating on protein separation using monolithic columns in reversed-phase chromatography.

    Science.gov (United States)

    Mann, Benjamin F; Makarov, Alexey A; Wang, Heather; Welch, Christopher J

    2017-03-17

    Pressure is not typically controlled or adjusted independently of flow rate during method development in reversed-phase LC (RPLC). However, it has been shown that pressure has an effect on analyte molecular molar volume, and the magnitude of this effect is greater for proteins and ionizable compounds than neutral small molecules. This phenomenon has received attention recently in the context of porous sub-2-micron particle packed columns. The present study surveys the effect of pressure and frictional heating on RPLC separations using commercially-available monolithic columns at constant flow rate and with controlled external temperature. Because the current monoliths cannot be operated at high pressures, all experiments were conducted with pressures at or below 200bar. Nonetheless, substantial changes in retention were still observed; for example, an increase in pressure of 75bar shifted the retention factor for bovine insulin from 1.27 to 1.78, a 40% increase, while a similar experiment with the neutral small molecule, toluene, showed no change in retention. Results are presented from investigations of model peptides and proteins ranging in size from 1kDa to 30kDa, as well as experiments performed with a silica-based C18 monolith and a polystyrene divinylbenzene monolith functionalized with a phenyl stationary phase. This work indicates that protein separations in monoliths are highly pressure sensitive, and pressure should therefore be considered as an additional parameter in method development for optimizing retention and selectivity. Given these findings, and the ever-increasing importance of chromatographic separations of proteins in both industrial and academic laboratories, improved instrumentation and mechanisms for directly controlling system backpressure could be of great practical value. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. High-performance liquid chromatography analysis of polyacetylenes and polyenes in Echinacea pallida by using a monolithic reversed-phase silica column.

    Science.gov (United States)

    Pellati, Federica; Calò, Samuele; Benvenuti, Stefania

    2007-05-11

    In this study, a RP-HPLC method for the analysis of polyacetylenes and polyenes in Echinacea pallida roots and phytopharmaceuticals was developed. The reference compounds used for quantification were isolated from the plant material and their structures were determined on the basis of the analysis of UV, IR, NMR and MS data. The complete structure elucidation of three compounds, namely 8-hydroxy-tetradec-(9E)-ene-11,13-diyn-2-one (1), tetradec-(8Z)-ene-11,13-diyn-2-one (6) and pentadec-(8Z)-en-2-one (9) is described. In the analysis of the n-hexane extracts of E. pallida roots, the comparison between conventional and monolithic columns showed that the elution order in both cases is identical and the selectivity is equivalent. However, the retention times achieved by the monolithic column are shorter, resulting in a faster separation (20 min). Therefore, the analyses were carried out on a Chromolith Performance RP-18e (100 mm x 4.6 mm i.d.), with a gradient mobile phase composed by H(2)O and ACN at the flow rate of 2 mL/min. The column was thermostatted at 20 degrees C. The photodiode array detector monitored the eluent at 210 nm. The validation procedure confirmed that this technique affords reliable analysis of these components and is appropriate for the quality control of complex matrices, such as E. pallida roots and phytopharmaceuticals.

  19. Parallel imaging methods for phased array MRI

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Two parallel methods for magnetic resonance imaging (MRI) using radio frequency (RF) phased array surface coils, named spatial local Fourier encoding (SLFE) and spatial RF encoding (SRFE), are presented. The MR signals are acquired from separate channels across the coils, each of which covers a sub-FOV (field-of-view) in a parallel fashion, and the acquired data are combined to form an image of entire FOV. These two parallel encoding techniques can accelerate MR imaging greatly, yet associated artifact may appear, although the SLFE is an effective image reconstruction method which can reduce the localized artifact in some degrees. By the SRFE, RF coil array can be utilized for spatial encoding through a specialized coil design. The images are acquired in a snapshot with a high signal-to-noise ratio (SNR) without the costly gradient system, resulting in great saving of cost. Both mutual induction and aliasing effect of adjacent coils are critical to the success of SRFE. The strategies of inverse source problem and wavelet transform (WT) can be employed to eliminate them. The results simulated by MATLAB are reported.

  20. Wavelet Analysis for Acoustic Phased Array

    Science.gov (United States)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

    Wavelet spectrum analysis is known to be one of the most powerful tools for exploring quasistationary signals. In this paper we use wavelet technique to develop a new Direction Finding (DF) Algorithm for the Acoustic Phased Array (APA) systems. Utilising multi-scale analysis of libraries of wavelets allows us to work with frequency bands instead of individual frequency of an acoustic source. These frequency bands could be regarded as features extracted from quasistationary signals emitted by a noisy object. For detection, tracing and identification of a sound source in a noisy environment we develop smart algorithm. The essential part of this algorithm is a special interacting procedure of the above-mentioned DF-algorithm and the wavelet-based Identification (ID) algorithm developed in [4]. Significant improvement of the basic properties of a receiving APA pattern is achieved.

  1. Quantitative flaw characterization with ultrasonic phased arrays

    Science.gov (United States)

    Engle, Brady John

    Ultrasonic nondestructive evaluation (NDE) is a critical diagnostic tool in many industries. It is used to characterize potentially dangerous flaws in critical components for aerospace, automotive, and energy applications. The use of phased array transducers allows for the extension of traditional techniques and the introduction of new methods for quantitative flaw characterization. An equivalent flaw sizing technique for use in time-of-flight diffraction setups is presented that provides an estimate of the size and orientation of isolated cracks, surface-breaking cracks, and volumetric flaws such as voids and inclusions. Experimental validation is provided for the isolated crack case. A quantitative imaging algorithm is developed that corrects for system effects and wave propagation, making the images formed directly related to the properties of the scatterer present. Simulated data is used to form images of cylindrical and spherical inclusions. The contributions of different signals to the image formation process are discussed and examples of the quantitative nature of the images are shown.

  2. Multiband Photonic Phased-Array Antenna

    Science.gov (United States)

    Tang, Suning

    2015-01-01

    A multiband phased-array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. Crystal Research, Inc., has developed a multiband photonic antenna that is based on a high-speed, optical, true-time-delay beamformer. It is capable of simultaneously steering multiple independent radio frequency (RF) beams in less than 1,000 nanoseconds. This high steering speed is 3 orders of magnitude faster than any existing optical beamformer. Unlike other approaches, this technology uses a single controlling device per operation band, eliminating the need for massive optical switches, laser diodes, and fiber Bragg gratings. More importantly, only one beamformer is needed for all antenna elements.

  3. Photonic Integrated Circuits for Phased-Array Beamforming

    NARCIS (Netherlands)

    Vliet, F.E. van; Stulemeijer, J.; Benoist, K.W.; Maat, D.H.P.; Smit, M.K.; Dijk, R. van

    1999-01-01

    Photonic integration is very promising to bring down volume and weight of phased-array beamforming networks. In addition, photonics allows for increased functionality for wide bandwidth systems. In this paper we demonstrate the feasibiÌity of phase and amplitude control of a 16-elernent phased-array

  4. Monolithic, High-Speed Fiber-Optic Switching Array for Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase II effort will develop a 1 x 10 prototype non-mechanical fiber optic switch for use with high power lasers. The proposed optical device is a...

  5. The First Monolithic Silicon Carbide Active Pixel Sensor Array for Solar Blind UV Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will address the needs of space astronomy, military threat detection, and scientific research for image...

  6. Selective higher order fiber mode excitation using a monolithic setup of a phase plate at a fiber facet

    CERN Document Server

    Wilde, Johannes; Brüning, Robert; Duparré, Michael; Schröter, Siegmund

    2015-01-01

    Controlling the modal content coupled into an optical fiber can be desireable in many situations, e.g. for adjusting the sensitivity of the guided field distribution to external perturbations. For this purpose we used a monolithic setup of a phase plate at a fiber inpute facet to excite selectivly higher order modes, which theoretically can provide a mode purity of more than 99%. We investigated the capabilities of this approach by complete modal decomposition of the fiber output signals, considering the achievable mode purity with respect to several possible imperfections of the setup. The experiments are compared with detailed numerical simulations and show a high agreement. Additionally a comparison with a well known setup with free space phase plates was undertaken. This showed the monolithic setup to be energetically twice as efficient.

  7. Phased-array vector velocity estimation using transverse oscillations

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt

    2012-01-01

    A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicabil......A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical...

  8. PREPARATION OF POROUS NANOCOMPOSITE SCAFFOLDS WITH HONEYCOMB MONOLITH STRUCTURE BY ONE PHASE SOLUTION FREEZE DRYING METHOD

    Institute of Scientific and Technical Information of China (English)

    Yang Xu; Duo Zhang; Zong-liang Wang; Zhan-tuan Gao; Pei-biao Zhang; Xue-si Chen

    2011-01-01

    Biodegradable porous nanocomposite scaffolds of poly(lactide-co-glycolide) (PLGA) and L-lactic acid (LAc) oligomer surface-grafted hydroxyapatite nanoparticles (op-HA) with a honeycomb monolith structure were fabricated with the single-phase solution freeze-drying method. The effects of different freezing temperatures on the properties of the scaffolds, such as microstructures, compressive strength, cell penetration and cell proliferation were studied. The highly porous and well interconnected scaffolds with a tunable pore structure were obtained. The effect of different freezing temperature (4℃, -20℃, -80℃ and -196℃) was investigated in relation to the scaffold morphology, the porosity varied from 91.2% to 83.0% and the average pore diameter varied from (167.2 ± 62.6) pm to (11.9 ± 4.2) μm while the σ10 increased significantly. The cell proliferation were decreased and associated with the above-mentioned properties. Uniform distribution of op-HA particles and homogeneous roughness of pore wall surfaces were found in the 4℃ frozen scaffold. The 4℃ frozen scaffold exhibited better cell penetration and increased cell proliferation because of its larger pore size, higher porosity and interconnection. The microstmctures described here provide a new approach for the design and fabrication of op-HA/PLGA based scaffold materials with potentially broad applicability for replacement of bone defects.

  9. Substrate Integrated Waveguide Based Phase Shifter and Phased Array in a Ferrite Low Temperature Co-fired Ceramic Package

    KAUST Repository

    Nafe, Ahmed A.

    2014-03-01

    Phased array antennas, capable of controlling the direction of their radiated beam, are demanded by many conventional as well as modern systems. Applications such as automotive collision avoidance radar, inter-satellite communication links and future man-portable satellite communication on move services require reconfigurable beam systems with stress on mobility and cost effectiveness. Microwave phase shifters are key components of phased antenna arrays. A phase shifter is a device that controls the phase of the signal passing through it. Among the technologies used to realize this device, traditional ferrite waveguide phase shifters offer the best performance. However, they are bulky and difficult to integrate with other system components. Recently, ferrite material has been introduced in Low Temperature Co-fired Ceramic (LTCC) multilayer packaging technology. This enables the integration of ferrite based components with other microwave circuitry in a compact, light-weight and mass producible package. Additionally, the recent concept of Substrate Integrated Waveguide (SIW) allowed realization of synthesized rectangular waveguide-like structures in planar and multilayer substrates. These SIW structures have been shown to maintain the merits of conventional rectangular waveguides such as low loss and high power handling capabilities while being planar and easily integrable with other components. Implementing SIW structures inside a multilayer ferrite LTCC package enables monolithic integration of phase shifters and phased arrays representing a true System on Package (SoP) solution. It is the objective of this thesis to pursue realizing efficient integrated phase shifters and phased arrays combining the above mentioned technologies, namely Ferrite LTCC and SIW. In this work, a novel SIW phase shifter in ferrite LTCC package is designed, fabricated and tested. The device is able to operate reciprocally as well as non-reciprocally. Demonstrating a measured maximum

  10. Non-integral dimensions ultrasonic phased arrays in a borehole

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bixing; ZHANG Chengguang; Deng Fangqing

    2009-01-01

    The non-integral dimensions ultrasonic phased arrays and their scanning and test-ing methods in a borehole are studied. First, the focusing acoustic fields excited by the 1.25D, 1.5D, and 1.75D phased arrays are analyzed, and then the imaging resolution in the elevation direction and the influence of the dynamic elements are investigated. Second, the focusing and deflexion characteristics of the acoustic fields excited by the annular and segmented annular phased arrays are studied, and they are compared with those excited by the 2D surface array. The application method of the 1.25D, 1.5D, and 1.75D, annular and segmented annular phased arrays in acoustic logging are analyzed and discussed. It provides a theoretical foundation for the application of the ultrasonic phased arrays in acoustic logging.

  11. A novel method to design sparse linear arrays for ultrasonic phased array.

    Science.gov (United States)

    Yang, Ping; Chen, Bin; Shi, Ke-Ren

    2006-12-22

    In ultrasonic phased array testing, a sparse array can increase the resolution by enlarging the aperture without adding system complexity. Designing a sparse array involves choosing the best or a better configuration from a large number of candidate arrays. We firstly designed sparse arrays by using a genetic algorithm, but found that the arrays have poor performance and poor consistency. So, a method based on the Minimum Redundancy Linear Array was then adopted. Some elements are determined by the minimum-redundancy array firstly in order to ensure spatial resolution and then a genetic algorithm is used to optimize the remaining elements. Sparse arrays designed by this method have much better performance and consistency compared to the arrays designed only by a genetic algorithm. Both simulation and experiment confirm the effectiveness.

  12. A new anion-exchange/hydrophobic monolith as stationary phase for nano liquid chromatography of small organic molecules and inorganic anions.

    Science.gov (United States)

    Aydoğan, Cemil

    2015-05-01

    In this study, an anion-exchange/hydrophobic polymethacrylate-based stationary phase was prepared for nano-liquid chromatography of small organic molecules and inorganic anions. The stationary phase was synthesized by in situ polymerization of 3-chloro-2-hydroxypropylmethacrylate and ethylene dimethacrylate inside silanized 100 μm i.d. fused silica capillary. The porogen mixture consisted of toluene and dodecanol. The pore size distrubution profiles of the resulting monolith were determined by mercury intrusion porosimetry and the morphology of the prepared monolith was investigated by scanning electron microscope. Good permeability, stability and column efficiency were observed on the monolithic column with nano flow. The produced monolithic column, which contains reactive chloro groups, was then modified by reaction with N,N-dimethyl-N-dodecylamine to obtain an anion-exchange/hydrophobic monolithic stationary phase. The functionalized monolith contained ionizable amine groups and hydrophobic groups that are useful of anion-exchange/hydrophobic mixed-mode chromatography. The final monolithic column performance with respect to anion-exchange and hydrophobic interactions was assesed by the separation of alkylbenzene derivatives, phenolic compounds and inorganic anions, respectively. Theoretical plate numbers up to 23,000 plates/m were successfully achieved in the separation of inorganic anions.

  13. Phased Array - the path to future weld inspection?; Phased Array - der Weg zur zukuenftigen Schweissnahtpruefung?

    Energy Technology Data Exchange (ETDEWEB)

    Koeppke, Gerd [HORA Holter Regelarmaturen GmbH und Co. KG, Schloss Holte-Stukenbrock (Germany)

    2008-12-15

    Although much has already been written and reported concerning phased-array inspection systems, practical implementation still remains in its infancy. A number of factors, such as customer-acceptance, for example, complicate the application of this modified ultrasonic inspection method. The following technical article examines the advantages and quality of this inspection procedure on the basis of a comparative test performed at Holter Regelarmaturen GmbH. (orig.)

  14. Porous Monoliths: Stationary Phases of Choice for High Performance Liquid Chromatography in Various Formats%用于高效液相色谱的不同形式的多孔整体固定相

    Institute of Scientific and Technical Information of China (English)

    SVEC Frantisek

    2005-01-01

    Modern porous monoliths have been conceived as a new class of stationary phases for high performance liquid chromatography (HPLC) in classical columns in the early 1990s and later extended to the capillary format. These monolithic materials are prepared using simple processes carried out in an external mold (inorganic monoliths) or within the confines of the column (organic monoliths and all capillary columns). These methods afford macroporous materials with large through-pores that enable applications in a rapid flow-through mode. Since all the mobile phase must flow through the monolith, the convection considerably accelerates mass transport within the monolithic separation medium and improves the separations. As a result, the monolithic columns perform well even at very high flow rates. The applications of monolithic capillary columns are demonstrated on numerous separations in the HPLC mode.

  15. Monolithic LaBr3 : Ce crystals on silicon photomultiplier arrays for time-of-flight positron emission tomography

    NARCIS (Netherlands)

    Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Schaart, Dennis R.

    2012-01-01

    Positron emission tomography detectors based on monolithic scintillation crystals exhibit good spatial and energy resolution, intrinsically provide depth-of-interaction information, have high gamma-photon capture efficiency, and may reduce the manufacturing costs compared to pixelated crystal

  16. Design and Realization of Array Signal Processor VLSI Architecture for Phased Array System

    Directory of Open Access Journals (Sweden)

    D. Govind Rao

    2016-08-01

    Full Text Available A method for implementing an array signal processor for phased array radars. The array signal processor can receive planar array antenna inputs and can process it. It is based on the application of Adaptive Digital beam formers using FPGAs. Adaptive filter algorithm used here is Inverse Q-R Decomposition based Recursive Least Squares (IQRD-RLS [1] algorithm. Array signal processor based on FPGAs is suitable in the areas of Phased Array Radar receiver, where speed, accuracy and numerical stability are of utmost important. Using IQRD-RLS algorithm, optimal weights are calculated in much less time compared to conventional QRD-RLS algorithm. A customized multiple FPGA board comprising three Kintex-7 FPGAs is employed to implement array signal processor. The proposed architecture can form multiple beams from planar array antenna elements

  17. Optimizing Satellite Communications With Adaptive and Phased Array Antennas

    Science.gov (United States)

    Ingram, Mary Ann; Romanofsky, Robert; Lee, Richard Q.; Miranda, Felix; Popovic, Zoya; Langley, John; Barott, William C.; Ahmed, M. Usman; Mandl, Dan

    2004-01-01

    A new adaptive antenna array architecture for low-earth-orbiting satellite ground stations is being investigated. These ground stations are intended to have no moving parts and could potentially be operated in populated areas, where terrestrial interference is likely. The architecture includes multiple, moderately directive phased arrays. The phased arrays, each steered in the approximate direction of the satellite, are adaptively combined to enhance the Signal-to-Noise and Interference-Ratio (SNIR) of the desired satellite. The size of each phased array is to be traded-off with the number of phased arrays, to optimize cost, while meeting a bit-error-rate threshold. Also, two phased array architectures are being prototyped: a spacefed lens array and a reflect-array. If two co-channel satellites are in the field of view of the phased arrays, then multi-user detection techniques may enable simultaneous demodulation of the satellite signals, also known as Space Division Multiple Access (SDMA). We report on Phase I of the project, in which fixed directional elements are adaptively combined in a prototype to demodulate the S-band downlink of the EO-1 satellite, which is part of the New Millennium Program at NASA.

  18. Inspection of pipeline girth welds with ultrasonic phased array technique

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A novel automatic ultrasonic system used for the inspection of pipeline girth welds is developed, in which a linear phased array transducer using electronic scan is adopted. Optimal array parameters are determined based on a mathematical model of acoustic field for linear phased array derived from Huygens' principle. The testing method and the system structure are introduced. The experimental results show that the phased array transducer system has the same detectability as that of conventional ultrasonic transducer system, but the system architecture can be simplified greatly, and the testing flexibility and the testing speed can be improved greatly.

  19. Direct tandem mass spectrometric analysis of amino acids in plasma using fluorous derivatization and monolithic solid-phase purification.

    Science.gov (United States)

    Tamashima, Erina; Hayama, Tadashi; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-11-10

    In this study, we developed a novel direct tandem mass spectrometric method for rapid and accurate analysis of amino acids utilizing a fluorous derivatization and purification technique. Amino acids were perfluoroalkylated with 2H,2H,3H,3H-perfluoroundecan-1-al in the presence of 2-picoline borane via reductive amination. The derivatives were purified by perfluoroalkyl-modified silica-based monolithic solid-phase extraction (monolithic F-SPE), and directly analyzed by tandem mass spectrometry using electrospray ionization without liquid chromatographic separation. The perfluoroalkyl derivatives could be sufficiently distinguished from non-fluorous compounds, i.e. the biological matrix, due to their fluorous interaction. Thus, rapid and accurate determination of amino acids was accomplished. The method was validated with human plasma samples and applied to the analysis of amino acids in the plasma of mice with maple syrup urine disease or phenylketonuria.

  20. Phased array antenna element for automotive radar application

    OpenAIRE

    2014-01-01

    In this thesis work, a design of reliable antenna front-end for W band automotive radar is studied and the problems and considerations associated with phased array antenna design at W-band are addressed. Proposed phased array antenna consists of on chip patch antenna which has the advantages of being integrated by the active circuitry. A sample of patch antenna and patch array are designed and fabricated to be tested for their functionality. Printing antenna on Silicon substrate is a compact ...

  1. Phased Array Transmit Antenna for a Satellite

    Science.gov (United States)

    Huggins, R. W.; Heisen, P. T.; Miller, G. E.; McMeen, D. J.; Perko, K. L.

    1999-01-01

    Active phased array antennas with electronically scanned beams offer advantages over high gain parabolic dish antennas currently used on spacecraft. Benefits include the elimination of deployable structures, no moving parts, and no torque disturbances that moving antennas impart to the spacecraft. The latter results in the conservation of spacecraft power, and the ability to take precision optical data while transmitting data. Such an antenna has been built under a contract from NASA Goddard Space Flight Center for the New Millennium Program EO- 1 satellite where it will act as the primary highspeed scientific data communication link. The antenna operates at X-band, has an integral controller and power conditioner, communicates with the spacecraft over a 1773 optical data bus, and is space qualified for low earth orbit (705 Km altitude). The nominal mission length is one year, and the operational requirement is for one 10 minute transmission a day over Spitsbergen, Norway. Details of the antenna and its performance will be described in the following paper.

  2. Impact of mobile phase composition on the performance of porous polymeric monoliths in the elution of small molecules.

    Science.gov (United States)

    Causon, Tim J; Hilder, Emily F; Nischang, Ivo

    2012-11-09

    The influence of mobile phase solvent composition and consequently retention factor on the chromatographic performance for a set of small molecules was studied using a commercially available poly(styrene-co-divinyl benzene) analytical scale porous polymeric monolithic column as an example. Chromatographic elution performance was studied across retention factors from close to 0 up to 100 realized for a set of structurally similar small molecules in a binary reversed-phase solvent environment of acetonitrile and water. By altering the mobile phase composition from volume fractions of acetonitrile of just 10% (v/v) to only acetonitrile it was systematically shown that gel porosity of the monolithic column plays a dominant role in modulating mass transport and the associated chromatographic efficiency in a consistent manner. Up to a sixfold difference in plate height was recorded for the most strongly retained hydrophobic solute (ethylbenzene) at a constant, low flow velocity simply by varying the amount of acetonitrile in the mobile phase. Plate height curves recorded for the set of solutes that comprise benzene, toluene, ethylbenzene as well as phenol and benzyl alcohol further demonstrate the importance of functional group content of the solute and the modulated porous gel structure on mass transport. These results highlight some important practical considerations for characterizing the chromatographic properties of any polymeric monolithic column. First, it is imperative that any chromatographic performance characterization using plate height data explicitly considers the influence of mobile phase composition, retention factor, molecular size and functional groups of the probe solute. Second, as the physicochemical conditions of the material are directly reflected in the gel porosity, a range of different mobile phase compositions, retention factors and probe-specific effects must be investigated to yield a fair appraisal of the chromatographic performance.

  3. Guided wave phased array beamforming and imaging in composite plates.

    Science.gov (United States)

    Yu, Lingyu; Tian, Zhenhua

    2016-05-01

    This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise. For array characterization, the beam pattern of rectangular grid arrays in composite plates is derived. In addition to the beam pattern, the beamforming factor in terms of wavenumber distribution is defined to provide intrinsic explanations for phased array beamforming. The beamforming and damage detection in a composite plate are demonstrated using rectangular grid arrays made by a non-contact scanning laser Doppler vibrometer. Detection images of the composite plate with multiple surface defects at various directions are obtained. The results show that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

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

    Science.gov (United States)

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

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

  5. Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid phase microextraction coupled to high performance liquid chromatography and analysis of amphetamines in urine samples.

    Science.gov (United States)

    Fan, Yi; Feng, Yu-Qi; Zhang, Jian-Tao; Da, Shi-Lu; Zhang, Min

    2005-05-13

    In-tube solid-phase microextraction (SPME) based on a poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was investigated for the extraction of amphetamine, methamphetamine and their methylenedioxy derivatives. The monolithic capillary column showed high extraction efficiency towards target analytes, which could be attributed to its larger loading amount of extraction phase than conventional open-tubular extraction capillaries and the convective mass transfer procedure provided by its monolithic structure. The extraction mechanism was studied, and the results indicated that the extraction process of the target analytes was involved with hydrophobic interaction and ion-exchange interaction. The polymer monolith in-tube SPME-HPLC system with UV detection was successfully applied to the determination of amphetamine, methamphetamine and their methylenedioxy derivatives in urine samples, yielding the detection limits of 1.4 - 4.0 ng/mL. Excellent method reproducibility (RSD urine samples.

  6. A Fully Reconfigurable Polarimetric Phased Array Antenna Testbed

    Directory of Open Access Journals (Sweden)

    Sudantha Perera

    2014-01-01

    Full Text Available The configurable phased array demonstrator (CPAD is a low-cost, reconfigurable, small-scale testbed for the dual-polarized array antenna and radar prototype. It is based on the concept that individual transmit and receive (TR modules and radiating elements can be configured in different ways to study the impact of various array manifolds on radiation pattern performance. For example, CPAD is configured as (a a 4 × 4 planar array, (b a planar array with mirror configuration, and (c a circular array to support the multifunctional phased array radar (MPAR system risk reduction studies. System descriptions are given in detail, and measurements are made and results are analyzed.

  7. Array antennas design in dependence of element-phasing

    Science.gov (United States)

    Zichner, R.; Chandra, M.

    2009-05-01

    Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular), distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  8. Array antennas design in dependence of element-phasing

    Directory of Open Access Journals (Sweden)

    R. Zichner

    2009-05-01

    Full Text Available Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular, distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  9. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    Science.gov (United States)

    Host, Nick; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix

    2013-01-01

    Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex, heavy and most importantly costly. This presentation paper presents a concept which overcomes these detrimental attributes by eliminating all of the phase array backend (including phase shifters). Instead, a wave velocity reconfigurable transmission line is used in a series fed array arrangement to allow phase shifting with one small (100mil) mechanical motion. Different configurations of the reconfigurable wave velocity transmission line are discussed and simulated and experimental results are presented.

  10. Sub-array patterns of spherical-section phased array for high intensity focused ultrasound surgery

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaodong; WANG Xufei; LU Mingzhu; WAN Mingxi

    2005-01-01

    The sub-array field patterns of spherical-section phased array were implemented for noninvasive ultrasound surgery of liver-tumor. The sub-array approach included field calculation, pseudo-inverse method and genetic algorithm. The sub-arrays uncovered by ribs according to scanned images normally emitted ultrasound. The results from different sub-arrays demonstrated quite satisfied acoustic performances, which included qualified focus size and intensity level for ultrasound surgery with single-focus and multi-foci patterns. Moreover, the patterns could decrease power accumulation on the ribs, and avoid damaging normal tissues. Thus the sub-array method provides a promising tool for phased array ultrasound propagating through strong obstacles like human rib cage, and it may broaden the therapeutic area, make the surgery safer and more flexible.

  11. Molecularly imprinted solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of safranine T in wolfberry.

    Science.gov (United States)

    Su, Zihao; Zhai, Haiyun; Chen, Zuanguang; Zhou, Qing; Li, Jiangmei; Liu, Zhenping

    2014-02-01

    A method was developed to sensitively determine safranine T in wolfberry by molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using safranine T, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions and the morphologies of inner polymers were characterized by scanning electron microscopy (SEM). The mean recoveries of safranine T in wolfberry ranged from 91.2 % to 92.9 % and the intraday and interday relative standard deviation (RSD) values all ranged from 3.4 % to 4.2 %. Good linearity was obtained over 0.001-1.0 μg mL(-1) (r = 0.9999) with a detection limit (S/N = 3) of 0.4 ng g(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and the extraction on the monolithic column effectively cleaned up the wolfberry matrix. The results demonstrated that the proposed MISPE-HPLC-LIF method could be applied to sensitively determine safranine T in wolfberry.

  12. Ultrasonic guided wave focusing by a generalized phased array

    Science.gov (United States)

    Zhang, Bixing; Xie, Fuli; Dong, Hefeng; Gong, Junjie

    2013-01-01

    Ultrasonic guided wave focusing by a generalized phased array is studied based on dispersion curves in a multi-layered medium. The different phase of the guided waves with different frequency is added on the excitation signal on each element of the transducer array for focusing. This can be realized by designing a proper excitation pulse based on the dispersion curves of the guided waves for each of the transducer array elements. The numerical simulation results show that the guided waves with different modes, different frequency components, and from different elements of the transducer array can all be focused at the target and focusing is achieved.

  13. Microwave power transmitting phased array antenna research project

    Science.gov (United States)

    Dickinson, R. M.

    1978-01-01

    An initial design study and the development results of an S band RF power transmitting phased array antenna experiment system are presented. The array was to be designed, constructed and instrumented to permit wireless power transmission technology evaluation measurements. The planned measurements were to provide data relative to the achievable performance in the state of the art of flexible surface, retrodirective arrays, as a step in technically evaluating the satellite power system concept for importing to earth, via microwave beams, the nearly continuous solar power available in geosynchronous orbit. Details of the microwave power transmitting phased array design, instrumentation approaches, system block diagrams, and measured component and breadboard characteristics achieved are presented.

  14. System-level integrated circuit (SLIC) development for phased array antenna applications

    Science.gov (United States)

    Shalkhauser, K. A.; Raquet, C. A.

    1991-01-01

    A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

  15. Preparation and evaluation of monolithic molecularly imprinted stationary phase for S-naproxen

    Institute of Scientific and Technical Information of China (English)

    De-Miao Chen; Qiang Fu; Wei Du; Si-Juan Sun; Ping Huang; Chun Chang

    2011-01-01

    An S-naproxen(S-NAP)molecularly imprinted monolithic stationary phase(MIMSP)with specific recognition for S-NAP and naproxen(NAP)was prepared by in situ technique,utilizing 4-vinylpridine(4-VP)as a function monomer,ethylene glycol dimethacrylate(EDMA)as a

  16. Hybrid organic-inorganic silica monolith with hydrophobic/strong cation-exchange functional groups as a sorbent for micro-solid phase extraction.

    Science.gov (United States)

    Zheng, Ming-Ming; Ruan, Ge-Deng; Feng, Yu-Qi

    2009-11-06

    A hybrid organic-inorganic silica monolith with hydrophobic and strong cation-exchange functional groups was prepared and used as a sorbent for micro-solid phase extraction (micro-SPE). The hybrid silica monolith functionalized with octyl and thiol groups was conveniently synthesized by hydrolysis and polycondensation of a mixture of tetraethoxysilane (TEOS), n-octyltriethoxysilane (C8-TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) via a two-step catalytic sol-gel process. Due to the favorable chemical reactivity of mercapto pendant moieties, the obtained hybrid monolith was oxidized using hydrogen peroxide (30%, w/w) to yield sulfonic acid groups, which provided strong cation-exchange sites. The obtained hybrid monolith was characterized by diffused infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The results show that the resulting monolith contains much higher carbon (31.6%) and sulfur (4.8%) contents than traditionally bonded silica materials. The extraction performance of the hybrid monolith was evaluated using sulfonamides as testing analytes by micro-SPE on-line coupled to HPLC. The results show that the hybrid monolith with hydrophobic and strong cation-exchange functional groups exhibits high extraction efficiency towards the testing analytes. The column-to-column RSD values were 1.3-9.8% for the extraction of SAs investigated. The extraction performance of the hybrid silica monolith remained practically unchanged after treated with acid (pH 1.0) and basic solutions (pH 10.5). Finally, the application of the hybrid monolith was demonstrated by micro-SPE of sulfonamide residues from milk followed by HPLC-UV analysis. The limits of detection (S/N=3) for eight SAs were found to be 1.0-3.0ng/mL in milk. The recoveries of eight SAs spiked in milk sample ranged from 80.2% to 115.6%, with relative standard deviations less than 11.8%.

  17. Phased-array sources based on nonlinear metamaterial nanocavities.

    Science.gov (United States)

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  18. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer

    OpenAIRE

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L.; Shung, K. Kirk; Zhang, Hao F.; Jiao, Shuliang

    2012-01-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experimen...

  19. Phased array ultrasonic inspection of Friction Stir Weldments

    Science.gov (United States)

    Lamarre, André; Moles, Michael; Lupien, Vincent

    2000-05-01

    Phased array ultrasonic inspection methods have been developed for the rapid inspection of Friction Stir Weldments (FSW) on Delta rocket cryogenic tanks. A comprehensive review was performed to identify NDE methods that are suitable for the detection of defects in this new welding process. The search included a review of traditional and advanced NDE methods that were capable of demonstrating both the sensitivity and inspection rates required for this examination. This paper will discuss the theory behind phased array techniques, fundamentals of several probe designs for FSW configurations, and the advantages of using phased arrays over conventional NDE methods for this applications.

  20. Design of monoliths through their mechanical properties.

    Science.gov (United States)

    Podgornik, Aleš; Savnik, Aleš; Jančar, Janez; Krajnc, Nika Lendero

    2014-03-14

    Chromatographic monoliths have several interesting properties making them attractive supports for analytics but also for purification, especially of large biomolecules and bioassemblies. Although many of monolith features were thoroughly investigated, there is no data available to predict how monolith mechanical properties affect its chromatographic performance. In this work, we investigated the effect of porosity, pore size and chemical modification on methacrylate monolith compression modulus. While a linear correlation between pore size and compression modulus was found, the effect of porosity was highly exponential. Through these correlations it was concluded that chemical modification affects monolith porosity without changing the monolith skeleton integrity. Mathematical model to describe the change of monolith permeability as a function of monolith compression modulus was derived and successfully validated for monoliths of different geometries and pore sizes. It enables the prediction of pressure drop increase due to monolith compressibility for any monolith structural characteristics, such as geometry, porosity, pore size or mobile phase properties like viscosity or flow rate, based solely on the data of compression modulus and structural data of non-compressed monolith. Furthermore, it enables simple determination of monolith pore size at which monolith compressibility is the smallest and the most robust performance is expected. Data of monolith compression modulus in combination with developed mathematical model can therefore be used for the prediction of monolith permeability during its implementation but also to accelerate the design of novel chromatographic monoliths with desired hydrodynamic properties for particular application.

  1. Transverse Oscillation Vector Velocity Estimation using a Phased Array Transducer

    DEFF Research Database (Denmark)

    Marcher, Jønne; Pihl, Michael Johannes; Seerup, Gert

    2012-01-01

    The Transverse Oscillation method has shown its commercial feasibility, providing the user with 2D velocity information. Todays implementation on commercial ultrasound platforms only support linear array transducers and are limited in depth. Extending the implementation to a phased array transducer...

  2. SU-E-T-163: Characterization of a Novel High Resolution 1D Silicon Monolithic Array for Small Field Commissioning and Quality Assurance

    Energy Technology Data Exchange (ETDEWEB)

    Bisello, F [FAU University Erlangen-Nuernberg, Erlangen, DE (Germany); IBA Dosimetry, Schwarzenbruck, DE (United States); McGlade, J; Wang, P; Kralik, J; Kosterin, P; Mooij, R; Solberg, T [University of Pennsylvenia, Philadelphia, PA (United States); Menichelli, D; Celi, J [IBA Dosimetry, Schwarzenbruck, DE (United States)

    2015-06-15

    Purpose: To study the suitability of a novel 1D silicon monolithic array for dosimetry of small radiation fields and for QA of high dose gradient treatment modalities (IMRT and SBRT). Methods: A 1D array composed of 4 monolithic silicon modules of 64 mm length and 1 mm pixel pitch was developed by IBA Dosimetry. Measurements were carried out for 6MV and 15MV photons on two commercial different linacs (TrueBeam and Clinac iX, Varian Medical Systems, Palo Alto, CA) and for a CyberKnife G4 (Accuray Inc., Sunnyvale, CA). The 1D array was used to measure output factors (OF), profiles and off axis correction factors (OACF) for the Iris CyberKnife variable collimator (5–60 mm). In addition, dose profiles (at the isocenter plane) were measured for multiple IMRT and SBRT treatment plans and compared with those obtained using EDR2radiographic film (Carestream Health, Rochester NY), a commercial 2D diode array and with the dose distribution calculated using a commercial TPS (Eclipse, Varian Medical Systems, Palo Alto, CA). Results: Due to the small pixel pitch of the detector, IMRT and SBRT plan profiles deviate from film measurements by less than 2%. Similarly, the 1D array exhibits better performance than the 2D diode array due to the larger (7 mm) pitch of that device. Iris collimator OFs measured using the 1D silicon array are in good agreement with the commissioning values obtained using a commercial stereotactic diode as well as with published data. Maximum deviations are < 3% for the smallest field (5 and 7.5mm) and below 1% for all other dimensions. Conclusion: We have demonstrated good performances of the array for commissioning of small photon fields and in patient QA, compared with diodes and film typically used in these clinical applications. The technology compares favorably with existing commercial solutions The presenting author is founded by a Marie Curie Early Initial Training Network Fellowship of the European Communitys Seventh Framework Programme under

  3. Advanced reflector characterization with ultrasonic phased arrays in NDE applications.

    Science.gov (United States)

    Wilcox, Paul D; Holmes, Caroline; Drinkwater, Bruce W

    2007-08-01

    Ultrasonic arrays are increasingly widely used in nondestructive evaluation (NDE) due to their greater flexibility and potentially superior performance compared to conventional monolithic probes. The characterization of small defects remains a challenge for NDE and is of great importance for determining the impact of a defect on the integrity of a structure. In this paper, a technique for characterizing reflectors with subwavelength dimensions is described. This is achieved by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms. The first algorithm is used to obtain information about reflector orientation and the second algorithm is used to distinguish between point-like reflectors that reflect uniformly in all directions and specular reflectors that have distinct orientations. Experimental results are presented using a commercial 64-element, 5-MHZ array on two aluminum test specimens that contain a number of machined slots and side-drilled holes. The results show that the orientation of 1-mm-long slots can be determined to within a few degrees and that the signals from 1-mm-long slots can be distinguished from that from a 1-mm-diameter circular hole. Techniques for quantifying both the orientation and the specularity of measured signals are presented and the effect of processing parameters on the accuracy of results is discussed.

  4. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer.

    Science.gov (United States)

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L; Shung, K Kirk; Zhang, Hao F; Jiao, Shuliang

    2012-11-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging.

  5. Phased annular array transducers for ultrasonic guided wave applications

    Science.gov (United States)

    Yan, Fei; Borigo, Cody; Liang, Yue; Koduru, Jaya P.; Rose, Joseph L.

    2011-04-01

    Mode and frequency control always plays an important role in ultrasonic guided wave applications. In this paper, theoretical understanding of guided wave excitations of axisymmetric sources on plate structures is established. It is shown that a wave number spectrum can be used to investigate the guided wave excitations of an axisymmetric source. The wave number spectrum is calculated from a Hankel transform of the axial source loading profile. On the basis of the theoretical understanding, phased annular array transducers are developed as a powerful tool for guided wave mode and frequency control. By applying appropriate time delays to phase the multiple elements of an annular array transducer, guided wave mode and frequency tuning can be achieved fully electronically. The phased annular array transducers have been successfully used for various applications. Example applications presented in this paper include phased annular arrays for guided wave beamforming and a novel ultrasonic vibration modal analysis technique for damage detection.

  6. Optoelectronic Infrastructure for RF/Optical Phased Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optoelectronic integrated circuits offer radiation-hard solutions for satellite systems with much improved SWPB (size, weight, power and bandwidth). The phased array...

  7. Improvement for the steering performance of liquid crystal phased array

    Institute of Scientific and Technical Information of China (English)

    SONG Yan; KONG Ling-jiang; CHEN Jun; ZHU Ying; YANG Jian-yu

    2009-01-01

    Optical phased array technology is introduced and the steering performances of liquid crystal phased array are discussed, several factors affecting the beam steering performances arc analyzed completely, also simple models for some typical factors are developed. Then, a new method based on iterating and modifying the output phase pattern of liquid crystal phase shifters is proposed. Using this method, the modified voltages applied on electrodes of liquid crystal phase shifters can be obtained, after applying the voltages, the influence of factors can be compensated to some extent; the steering angle accu-racy and efficiency with liquid crystal phased array can be improved. Through the simulation for the angle range from 0° to -1°, the error of steering angle can be reduced three orders of magnitude, and the efficiency can be increased almost 30% after several iterations.

  8. CFRP Structural Health Monitoring by Ultrasonic Phased Array Technique

    OpenAIRE

    Boychuk, A.S.; Generalov, A.S.; A.V. Stepanov

    2014-01-01

    International audience; The report deals with ultrasonic phased array (PA) application for high-loaded CFRP structural health monitoring in aviation. Principles of phased array technique and most dangerous types of damages are briefly described. High-performance inspection technology suitable for periodic plane structure check is suggested. The results of numerical estimation of detection probability for impact damages and delaminations by PA technique are presented. The experience of PA impl...

  9. Analysis of electrical performances of planar active phased array antennas with distorted array plane

    Institute of Scientific and Technical Information of China (English)

    Wang Congsi; Bao Hong; Zhang Fushun; Feng Xingang

    2009-01-01

    a planar phased array antenna with different distortions grades prove the validity of the model.Therefore,by the method,the antenna designers may set the reasonable requirement on the structural tolerance in manufacturing antenna.

  10. Fast, high-efficiency peptide separations on a 50-mu m reversed-phase silica monolith in a nanoLC-MS set-up

    NARCIS (Netherlands)

    Rieux, L; Lubda, D; Niederlander, HAG; Verpoorte, E; Bischoff, R

    2006-01-01

    Proteomic studies have stimulated the development of novel stationary phases in miniaturised chromatographic columns that permit high linear flow velocities and exhibit high resolving power. In this work, a 50-mu m reversed-phase silica-based monolith was chromatographically characterised for its us

  11. A Flexible Phased-MIMO Array Antenna with Transmit Beamforming

    Directory of Open Access Journals (Sweden)

    Wen-Qin Wang

    2012-01-01

    Full Text Available Although phased-array antennas have been widely employed in modern radars, the requirements of many emerging applications call for new more advanced array antennas. This paper proposes a flexible phased-array multiple-input multiple-output (MIMO array antenna with transmit beamforming. This approach divides the transmit antenna array into multiple subarrays that are allowed to overlap each subarray coherently transmits a distinct waveform, which is orthogonal to the waveforms transmitted by other subarrays, at a distinct transmit frequency. That is, a small frequency increment is employed in each subarray. Each subarray forms a directional beam and all beams may be steered to different directions. The subarrays jointly offer flexible operating modes such as MIMO array which offers spatial diversity gain, phased-array which offers coherent directional gain and frequency diverse array which provides range-dependent beampattern. The system performance is examined by analyzing the transmit-receive beampatterns. The proposed approach is validated by extensive numerical simulation results.

  12. Active cancellation of probing in linear dipole phased array

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2015-01-01

    In this book, a modified improved LMS algorithm is employed for weight adaptation of dipole array for the generation of beam pattern in multiple signal environments. In phased arrays, the generation of adapted pattern according to the signal scenario requires an efficient adaptive algorithm. The antenna array is expected to maintain sufficient gain towards each of the desired source while at the same time suppress the probing sources. This cancels the signal transmission towards each of the hostile probing sources leading to active cancellation. In the book, the performance of dipole phased array is demonstrated in terms of fast convergence, output noise power and output signal-to-interference-and noise ratio. The mutual coupling effect and role of edge elements are taken into account. It is established that dipole array along with an efficient algorithm is able to maintain multilobe beamforming with accurate and deep nulls towards each probing source. This work has application to the active radar cross secti...

  13. Ultrarapid quantitation of maize proteins by perfusion and monolithic reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Rodríguez-Nogales, J M; del Alamo, M; García, M C; Cifuentes, A; Marina, M L

    2009-04-22

    The main objective of this study was to develop a new methodology alternative to the classical Kjeldahl analysis for determining maize proteins in maize products and seeds. For that purpose, two different chromatographic methodologies using perfusion and monolithic stationary phases, both enabling rapid separations of maize proteins, were investigated. Due to the difficulty to find suitable standards for this type of analysis, three different maize products were initially tested as proteins standards: zein F4000, corn gluten meal, and maize flour. Different figures of merit (i.e., linearity, correlation coefficient, precision, limits of detection and quantitation), as well as the presence of matrix inferences, were investigated. The results obtained for the different chromatographic stationary phases and protein standards were compared in order to select the most suitable analytical conditions. Despite both perfusion and monolithic methodologies resulting, in general, as appropriate for the quantitation of maize proteins, the highest reduction of analysis time and lowest detection and determination limits provided by perfusion methodology enabled to select this one as the method of choice for the quantitation of maize proteins. Regarding the different protein standards studied in this work, in general the best results were obtained using the zein standard. Compared to Kjeldahl methodology, perfusion chromatography yields total protein contents in shorter analysis time while enabling the separation of the different kinds of proteins. Due to the high diversity and complexity of industrial maize products, the proposed chromatographic method could be a very useful tool for their routine analysis.

  14. Optical phased arrays with evanescently-coupled antennas

    Science.gov (United States)

    Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

    2015-03-24

    An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

  15. Simple Array Beam-Shaping Using Phase-Only Adjustments.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    Conventional beam-shaping for array antennas is accomplished via an amplitude-taper on the elemental radiators. It is well known that proper manipulation of the elemental phases can also shape the antenna far-field pattern. A fairly simple transformation from a desired amplitude-taper to a phase-taper can yield nearly equivalent results.

  16. Optical phased array radiating optical vortex with manipulated topological charges.

    Science.gov (United States)

    Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

    2015-02-23

    Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near field. Orbital angular momentum with topological charge of 4 can be obtained by controlling the phase distribution of the fundamental mode orbital angular momentum in each antenna element. Our results indicate this phased array may be utilized in high integrated optical communication systems.

  17. High-power phase locking of a fiber amplifier array

    Science.gov (United States)

    Shay, T. M.; Baker, J. T.; Sanchez, A. D.; Robin, C. A.; Vergien, C. L.; Zeringue, C.; Gallant, D.; Lu, Chunte A.; Pulford, Benjamin; Bronder, T. J.; Lucero, Arthur

    2009-02-01

    We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently combined.

  18. Model-based optimization of phased array ultrasonic testing

    Institute of Scientific and Technical Information of China (English)

    Sung-Jin; Song; Hak-Joon; Kim; Suk-Chull; Kang; Sung-Sik; Kang; Kyungcho; Kim; Myung-Ho; Song

    2010-01-01

    Simulation of phased array beams in dovetail and austenitic welds is conducted to optimize the setup of phased array ultrasonic testing(PAUT).To simulate the beam in such material with complex geometry or with characteristic of anisotropy and inhomogeneity, firstly,linear phased multi-Gaussian beam(LPMGB) models are introduced and discussed. Then,in the case of dovetail,wedge is designed to maximize the stable amplitude of the beam along the steering path;in the case of austenitic weld,modified focal law...

  19. Ultrasonic Phased-Array Characterization for NDE Applications

    Science.gov (United States)

    Hanley, John J.; Tennis, Richard F.; Pickens, Keith S.

    1995-01-01

    Southwest Research Institute (SwRI) recently fabricated and delivered the 100-channel Ultrasonic Phased-Array Testbed System (UPATS) for NASA's Langley Research Center. NASA prepared the specifications and provided the funding to develop UPATS in order to provide a tool for the improvement of ultrasonic nondestructive evaluation (NDE) and characterization of materials. UPATS incorporates state-of-the-art phased-array concepts such as beam steering, focusing, apodization, and phase-sensitive detection which make it possible to develop more sophisticated testing methodologies. It also can be used to investigate fundamental ultrasonic propagation and detection phenomena such as refraction, diffraction, scattering, and beam broadening.

  20. EMAT phased array: A feasibility study of surface crack detection.

    Science.gov (United States)

    Isla, J; Cegla, F

    2017-02-14

    Electromagnetic-acoustic transducers (EMATs) consist of a magnet and a coil. They are advantageous in some non-destructive evaluation (NDE) applications because no direct contact with the specimen is needed to send and receive ultrasonic waves. However, EMATs commonly require excitation peak powers greater than 1kW and therefore the driving electronics and the EMAT coils have to be bulky. This has hindered the development of EMAT phased arrays with characteristics similar to those of conventional piezoelectric phased arrays. Phased arrays are widely used in NDE because they offer superior defect characterization in comparison to single-element transducers. In this paper, we report a series of novel techniques and design elements that make it possible to construct an EMAT phased array that performs similarly to conventional piezoelectric arrays used in NDE. One of the key enabling features is the use of coded excitation to reduce the excitation peak power to less than 4.8W (24 Vpp and 200mA) so that racetrack coils with dimensions 3.2×18mm(2) can be employed. Moreover, these racetrack coils are laid out along their shortest dimension so that 1/3 of their area is overlapped. This helps to reduce the crosstalk between the coils, i.e., the array elements, to less than -15dB. We show that an 8-element EMAT phased array operating at a central frequency of 1MHz can be used to detect defects which have a width and a depth of 0.2 and 0.8mm respectively and are located on the surface opposite to the array.

  1. Code-modulated interferometric imaging system using phased arrays

    Science.gov (United States)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  2. Reconfigurable Infrared Phased-Array Semiconductor Metasurfaces

    Science.gov (United States)

    Schuller, Jon

    The ability to engineer the scattering phase of metamaterial constituents offers tremendous potential for constructing new classes of beam steering, shaping, and focusing technologies. Current methods for engineering phase rely on static geometry-based effects. In this talk we describe methods to dynamically tune the scattering phase of infrared semiconductor nanoantennas. We fabricate spherical silicon and germanium nanoparticles via femtosecond laser ablation and demonstrate size-dependent multipolar resonances throughout the infrared frequency range. We experimentally demonstrate that the resonance frequencies shift with doping, according to simple Drude models of free-carrier refraction. Using a combination of theoretical and analytical calculations we show that dynamically tuning free-carrier concentration can enable reconfigurable optical antennas and metasurfaces. Such dynamic tuning will enable reconfigurable photonic devices based on optical antenna and metamaterial concepts.

  3. Mechanical properties examined by nanoindentation for selected phases relevant to the development of monolithic uranium-molybdenum metallic fuels

    Science.gov (United States)

    Newell, Ryan; Park, Youngjoo; Mehta, Abhishek; Keiser, Dennis; Sohn, Yongho

    2017-04-01

    Nanomechanical properties, specifically the reduced modulus and hardness of several intermetallic and solid solution phases are reported to assist the development of the U-10 wt% Mo (U-10Mo) monolithic fuel system for research and test reactors. Findings from this study and reported values of mechanical properties provide data critical for understanding and predicting the structural behavior of the fuel system during fabrication and irradiation. The phases examined are products of interdiffusion and reaction between (1) the AA6061 cladding and the Zr diffusion barrier, namely (Al,Si)3Zr and Al3Zr, (2) the U-10Mo fuel and the Zr diffusion barrier, namely UZr2, Mo2Zr, and α-U, and (3) the U (or U-10Mo) and Mo, namely a mixture gradient of α- and γ-phases. The UC inclusions observed within the fuel alloy were also examined. Only phases present in thick or continuous microstructure on cross-sectioned fuel plates and diffusion couples were investigated for reduced modulus and hardness. Concentration-dependence of room-temperature reduced modulus in U solid solution with 0-10 wt% Mo was semi-quantitatively modeled based on mixture of α- and γ-phases and solid solutioning within the γ-phase.

  4. Design Considerations for Phased Array Modules

    Science.gov (United States)

    1980-11-01

    basica )ly designed for C7 operation. In pulsed mode of oporation however, peak pov:e%.’ of 150:7 at 10.52GHz wras obtained for psoc pulse lengths and...repeating the above calculations with the appropriate value of referer:ce phase ýP applied to each element. Bearing in mind the tedious algebra involved in

  5. Full-matrix capture with a customizable phased array instrument

    Science.gov (United States)

    Dao, Gavin; Braconnier, Dominique; Gruber, Matt

    2015-03-01

    In recent years, a technique known as Full-Matrix Capture (FMC) has gained some headway in the NDE community for phased array applications. It's important to understand that FMC is the method that the instrumentation acquires the ultrasonic signals, but further post-processing is required in software to create a meaningful image for a particular application. Having a flexible software interface, small form factor, excellent signal-to-noise ratio per acquisition channel on a 64/64 or 128/128 phased array module with FMC capability proves beneficial in both industrial implementation and in further investigation of post-processing techniques. This paper will provide an example of imaging with a 5MHz linear phased array transducer with 128 elements using FMC and a popular post-processing algorithm known as Total-Focus Method (TFM).

  6. Study of ultrasonic phased array inspection imaging technology for NDT

    Institute of Scientific and Technical Information of China (English)

    Shan Baohua; Duan Zhongdong; Ou Jinping

    2006-01-01

    A research about the ultrasonic phased array imaging principle from A-scan signal to B-scan image for nondestructive testing (NDT) was conducted in this paper, the ultrasonic phased array inspection imaging system used in industrial field was developed and the experiment was performed on the steel testing block by the system with 64 elements, 5MHz phased array transducer.Experimental results show that the flaws could be accurately detected and the flaws size could be estimated from the B-scan images, and the B-scan images could clearly show the location of the flaws, but the quality of Bscan images needs to be enhanced by digital signal processing and controlling dynamic focusing for improving the image resolution.

  7. A Study on TOFD Inspection Using Phased Array Ultrasonic Technique

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Byung Sik; Kim, Yong Sik; Lee, Hee Jong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Lee, Young Ho [Chungnam National University, Daejeon (Korea, Republic of)

    2005-08-15

    The techniques in order to measure the depth of defect in weldment and structure accurately have been developed. Many researches have made efforts to develop the methods for the accurate depth sizing of defect. TOFD is known as the most accurate method of various methods for measuring depth sizing. However, there is a possibility to miss defects because of the limitation of beam coverage for the ultrasound incident angle. In this study, the results for detectability and depth sizing using phased array ultrasonic technique for thick body were compared with those of conventional TOFD technique. It was experimentally confirmed that the phased array ultrasonic TOFD technique gives good detectability and accurate depth measurement for the various types of defects. The phased array ultrasonic TOFD technique developed in this study will contribute to increase the inspection reliability in thick component such as the pressure vessel of power generation industry

  8. System response in passively phased fiber amplifier arrays

    Science.gov (United States)

    Shakir, Sami A.; Culver, Bill; Nelson, Burke; Starcher, Yuji; Bates, George M.; Hedrick, Jerry W., Jr.

    2008-08-01

    System temporal response in passively phased fiber amplifier arrays dictates how fast a passively phased system can correct for phase fluctuations due to thermal and mechanical effects. The system response time was measured by employing a variable-speed mechanical chopper in the feedback loop of a passively phased system then measuring the on-axis output intensity of the system as a function of time. Observed relaxation oscillations are compared to theory. The system response time was measured to be about 20 μsec. We also find that passive phasing improved the system's beam stability and extraction efficiency.

  9. Postpolymerization modification of a hydroxy monolith precursor. Part I. Epoxy alkane and octadecyl isocyanate modified poly (hydroxyethyl methacrylate-co-pentaerythritol triacrylate) monolithic capillary columns for reversed-phase capillary electrochromatography.

    Science.gov (United States)

    Khadka, Shantipriya; El Rassi, Ziad

    2016-12-01

    A novel precursor monolithic capillary column referred to as "hydroxy monolith" or OHM was prepared by the in situ copolymerization of hydroxyethylmethacrylate (HEMA) with pentaerythritol triacrylate (PETA) yielding the neutral poly(HEMA-co-PETA) monolith. The neutral precursor OHM capillary thus obtained was subjected to postpolymerization modifications of the hydroxyl functional groups present on its surface with 1,2-epoxyalkanes catalyzed by boron trifluoride (BF3 ) ultimately providing Epoxy OHM C-m capillary column at varying alkyl chain lengths where m = 8, 12, 14, and 16 for RP-CEC. Also, the same precursor OHM was grafted with octadecyl isocyanate yielding Isocyanato OHM C-18 column to provide an insight into the effect of the nature of the linkage to the surface hydroxyl groups of the OHM precursor. While the epoxide reaction leaves on the surface of the OHM precursor hydroxy-ether linkages, the isocyanato reaction leaves carbamate linkages on the same surface of the OHM precursor. This study revealed that changing the alkyl chain length resulted in changing the column phase ratio (ϕ) and also the solute distribution constant (K). While increasing the surface alkyl chain length increased steeply the solute hydrophobic selectivity, i.e. methylene group selectivity, the nature of the ligand linkage produced different retention for the same solutes and affected the selectivity of slightly polar solutes. The various monoliths proved very useful for RP-CEC of different small solutes at varying polarity over a wide range of mobile phase composition. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A Simplified Theory of Coupled Oscillator Array Phase Control

    Science.gov (United States)

    Pogorzelski, R. J.; York, R. A.

    1997-01-01

    Linear and planar arrays of coupled oscillators have been proposed as means of achieving high power rf sources through coherent spatial power combining. In such - applications, a uniform phase distribution over the aperture is desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Notable among these are linear phase distributions resulting in steering of the output rf beam away from the broadside direction. The theory describing the operation of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. This has made it difficult to develop an intuitive understanding of the impact of oscillator tuning on phase control and has thus impeded practical application. In this work a simpl!fied theory is developed which facilitates intuitive understanding by establishing an analog of the phase control problem in terms of electrostatics.

  11. Solid-phase extraction based on ground methacrylate monolith modified with gold nanoparticles for isolation of proteins.

    Science.gov (United States)

    Vergara-Barberán, María; Lerma-García, María Jesús; Simó-Alfonso, Ernesto Francisco; Herrero-Martínez, José Manuel

    2016-04-21

    In this study, a novel polymeric material functionalized with gold nanoparticles (AuNPs) was prepared as solid-phase extraction (SPE) sorbent for isolation of proteins. The sorbent was synthesized from a powdered poly(glycidyl-co-ethylene dimethacrylate) monolith, and modified with ammonia, followed by immobilization of AuNPs on the pore surface of the material. To evaluate the performance of this SPE support, proteins were selected as test solutes, being the extraction conditions and other parameters (loading capacity and regenerative ability of sorbent) established. The results indicated that this sorbent could be employed to selectively capture proteins according to their pI, on the basis of the strong affinity of these biomacromolecules towards to AuNPs surface. The applicability of this sorbent was demonstrated by isolating protein species of interest (bovine serum albumin, cytochrome c and lectins in European mistletoe leaves), followed by SDS-PAGE analysis.

  12. Development of a large-area monolithic 4x4 MPPC array for a future PET scanner employing pixelized Ce:LYSO and Pr:LuAG crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T., E-mail: katou.frme.8180@asagi.waseda.j [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H.; Sato, G. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

    2011-05-11

    We have developed a new type of large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of a 4x4 matrix of 3x3 mm{sup 2} pixels. Each pixel comprises 3600 Geiger mode avalanche photodiodes (APDs) that achieve an average gain of 9.68x10{sup 5} at 71.9 V at 0 {sup o}C with variations of only {+-}7.2% over 4x4 pixels. Excellent uniformity was also obtained for photon detection efficiencies (PDE) of {+-}6.4%, whilst dark count rates at the single photoelectron (1 p.e.) level amounted to {approx_equal}2Mcps/pixel, measured at 0 {sup o}C. As the first step toward using the device in scintillation photon detectors, we fabricated a prototype gamma-ray camera consisting of an MPPC array optically coupled with a scintillator matrix, namely a 4x4 array of 3x3 x10 mm{sup 3} crystals. Specifically, we tested the performance with Ce-doped (Lu, Y){sub 2}(SiO{sub 4})O (Ce:LYSO), Pr-doped Lu{sub 3}Al{sub 5}O{sub 12} (Pr:LuAG) and 'surface coated' Pr:LuAG (Pr:LuAG (WLS)) matrices whereby the emission peak of Pr:LuAG was shifted from 310 to 420 nm via a wavelength shifter (WLS). Average energy resolutions of 13.83%, 14.70% and 13.96% (FWHM) were obtained for 662 keV gamma-rays, as measured at 0 {sup o}C with Ce:LYSO, Pr:LuAG and Pr:LuAG (WLS) scintillator matrices, respectively. We confirmed that the effective PDE for Pr:LuAG (WLS) had improved by more than 30% compared to original, non-coated Pr:LuAG matrix. These results suggest that a large-area monolithic MPPC array developed here could be promising for future medical imaging, particularly in positron emission tomography (PET).

  13. Radiation and reflection acoustical fields of an annular phased array

    Institute of Scientific and Technical Information of China (English)

    LAI Puxiang; ZHANG Bixing; WANG Chenghao

    2007-01-01

    The characteristics of the radiation and reflection acoustical fields of an annular phased array are investigated. The effects of the element number, element radius, interelement spacing, centre frequency, focus position, and other parameters on the radiation acoustical field of the annular phased array is theoretically studied. In experiment, an annular transducer with 8 equal-area elements is designed and fabricated, and a series of experimental measurements are conducted. The radiation acoustical field and its reflection on a liquid-solid interface are theoretically and experimentally studied. The experimental result is in good agreement with the theoretical one.

  14. Monolithic Integration of GaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping, E-mail: jpao@ee.tokushima-u.ac.jp [Institute of Technology and Science, University of Tokushima 2-1 Minami-Josanjima, Tokushima 770-8506 (Japan)

    2011-02-01

    The technology of monolithically integrated GaN-based light-emitting diodes (LEDs) is reported. First, the technology details to realize monolithic integration are described, including the circuit design for high-voltage and alternating current (AC) operation and the technologies for device isolation. The performances of the fabricated monolithic LED arrays are then demonstrated. A monolithic series array with totally 40 LEDs exhibited expected operation function under AC bias. The operation voltage of the array is 72 V when 20 LEDs were connected in series. Some modified circuit designs for high-voltage operation and other monolithic LED arrays are finally reviewed.

  15. Graphene aerogel based monolith for effective solid-phase extraction of trace environmental pollutants from water samples.

    Science.gov (United States)

    Han, Qiang; Liang, Qionglin; Zhang, Xiaoqiong; Yang, Liu; Ding, Mingyu

    2016-05-20

    Graphene aerogel (GA), a typical kind of three-dimensional (3D) macroscopic assembly, not only provides inherently excellent properties of graphene sheets (GS), but also exhibits interesting characteristics of the 3D macroporous architecture including large and tunable pore volumes, high specific surface areas and fast mass transport kinetics. Thus, it is rational to expect GA to be an efficient adsorbent for solid-phase extraction (SPE). In this paper, a novel GA monolith based solid-phase extraction method was investigated in the application of environment analysis. The GA monolith based SPE cartridge was fabricated directly in the empty cartridge through template-free "sol-cryo" method. Due to the efficient mass transfer, more adsorption sites as well as effective retention for the analytes, the adsorption property of GA for bisphenol A revealed better performance than that of GS. What's more, GA also outperformed in loading and eluting for target analysis. On the basis of the above advantages, the obtained cartridge was applied for the separation of environmental pollutants from water samples. Taking endocrine disrupting chemicals and polychlorinated biphenyls as the polar and weak polar model analytes, optimizing several parameters influencing the recoveries, limits of detection in the range of 0.01-0.11ngmL(-1) and 0.19-1.53ngL(-1) for the two series of compounds were provided by the established methods. The satisfied sensitivity was accessed and recoveries ranging from 76.3 to 112.5% were obtained for all the analytes when the proposed methods were applied in real water samples analysis. The results revealed the potential of GA as an effective sorbent in sample preparation processes.

  16. Multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid with high-performance liquid chromatography for the determination of steroid sex hormones in water and urine.

    Science.gov (United States)

    Liao, Keren; Mei, Meng; Li, Haonan; Huang, Xiaojia; Wu, Cuiqin

    2016-02-01

    The development of a simple and sensitive analytical approach that combines multiple monolithic fiber solid-phase microextraction with liquid desorption followed by high-performance liquid chromatography with diode array detection is proposed for the determination of trace levels of seven steroid sex hormones (estriol, 17β-estradiol, testosterone, ethinylestradiol, estrone, progesterone and mestranol) in water and urine matrices. To extract the target analytes effectively, multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid was used to concentrate hormones. Several key extraction parameters including desorption solvent, extraction and desorption time, pH value and ionic strength in sample matrix were investigated in detail. Under the optimal experimental conditions, the limits of detection were found to be in the range of 0.027-0.12 μg/L. The linear range was 0.10-200 μg/L for 17β-estradiol, 0.25-200 μg/L estriol, ethinylestradiol and estrone, and 0.50-200 μg/L for the other hormones. Satisfactory linearities were achieved for analytes with the correlation coefficients above 0.99. Acceptable method reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations of both less than 8%. The enrichment factors ranged from 54- to 74-fold. Finally, the proposed method was successfully applied to the analysis of steroid sex hormones in environmental water samples and human urines with spiking recoveries ranged from 75.6 to 116%.

  17. A novel serrated columnar phased array ultrasonic transducer

    Science.gov (United States)

    Zou, Cheng; Sun, Zhenguo; Cai, Dong; Song, Hongwei; Chen, Qiang

    2016-02-01

    Traditionally, wedges are required to generate transverse waves in a solid specimen and mechanical rotation device is needed for interrogation of a specimen with a hollow bore, such as high speed railway locomotive axles, turbine rotors, etc. In order to eliminate the mechanical rotation process, a novel array pattern of phased array ultrasonic transducers named as serrated columnar phased array ultrasonic transducer (SCPAUT) is designed. The elementary transducers are planar rectangular, located on the outside surface of a cylinder. This layout is aimed to generate electrically rotating transverse waveforms so as to inspect the longitudinal cracks on the outside surface of a specimen which has a hollow bore at the center, such as the high speed railway locomotive axles. The general geometry of the SCPAUT and the inspection system are illustrated. A FEM model and mockup experiment has been carried out. The experiment results are in good agreement with the FEM simulation results.

  18. Microstrip Phased Array Antennas Printed on Inclined Planes

    Directory of Open Access Journals (Sweden)

    A. Papiernik

    1996-06-01

    Full Text Available This paper presents an analysis of the electromagnetic field radiated by micro-strip patch antennas printed on inclined surfaces. The theoretical approach allows to apply spatial rotations to each source. The computer simulation developed permits us to experiment different antenna structures and two original realisations are proposed: a 2-element array printed on two inclined planes and a 4-element array laid out on a pyramidal surface. In addition, it enables the choice of the phase applied to each radiator to produce a beam deflection function. A good accuracy is obtained between theoretical and experimental results. The aim of this study is to optimise the parameters of such antennas to achieve the desired radiation patterns, from printed phased arrays on conformal surfaces. We also present the theoretical behaviour of a octagonal pyramid.

  19. Solution-based photodetectors for monolithically integrated low-cost short-wave infrared focal plane arrays

    Science.gov (United States)

    Heves, Emre; Kayahan, Huseyin; Gurbuz, Yasar

    2013-05-01

    In this work, PbS Colloidal Quantum Dots (CQD) based photodiodes are realized on both silicon substrates and on the replicas of the ROICs in order to demonstrate fully integrated FPAs. Careful optimization of PbS CQD film formation and ligand exchange process, together with optimization of IC integrable process steps resulted in high performance, monolithically integrable photodiodes. High quantum efficiencies such as 32% is achieved for photodiodes on Si substrates and high responsivities up to 5,73 A/W is achieved for photodiodes on ROIC replicas. Also these detectors achieved very high normalized detectivities such as; 1.36 x 1011 Jones and 1.42 x 1012 Jones under 1V and 2V reverse bias respectively, which is close to conventional InGaAS SWIR detectors.

  20. Imaging for Borehole Wall by a Cylindrical Linear Phased Array

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bi-Xing; SHI Fang-Fang; WU Xian-Mei; GONG Jun-Jie; ZHANG Cheng-Guang

    2010-01-01

    @@ A new ultrasonic cylindrical linear phased array (CLPA) transducer is designed and fabricated for the borehole wall imaging in petroleum logging based on the previous theoretical researches.First,the CLPA transducer,which is made up of numbers of the piezoelectric elements distributed on the surface of a cylinder uniformly,is designed and fabricated.

  1. Phased arrays. Citations from the NTIS data base

    Science.gov (United States)

    Reed, W. E.

    1980-04-01

    The design, performance, radiation patterns, and applications of phased arrays are presented in these Federally-sponsored research reports. Applications include communications, radar, optical, spacecraft, and navigational aids. This updated bibliography contains 244 abstracts, 44 of which are new entries to the previous edition.

  2. High Resolution Processing with an Active Phased Array SAR

    NARCIS (Netherlands)

    Nijenboer, F.J.; Otten, M.P.G.

    1999-01-01

    The Dutch PHARUS system is a polarimetric active phased array SAR capable of performing advanced SAR modes. Advanced SAR modes that are being investigated are: spotlight SAR, sliding spotlight SAR, stepped frequency SAR and interferometric SAR. The flight experiments and automatic beam steering

  3. DVB-S Signal Tracking Techniques for Mobile Phased Arrays

    NARCIS (Netherlands)

    Blom, Koen C.H.; Burgwal, van de Marcel D.; Rovers, Kenneth C.; Kokkeler, André B.J.; Smit, Gerard J.M.

    2010-01-01

    Abstract—A system that uses adaptive beamforming techniques for mobile Digital Video Broadcasting Satellite (DVB-S) reception is proposed in this paper. The purpose is to enable DVB-S reception in moving vehicles. Phased arrays are able to electronically track the desired signal during dynamic behav

  4. Weak-signal Phase Calibration Strategies for Large DSN Arrays

    Science.gov (United States)

    Jones, Dayton L.

    2005-01-01

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

  5. Simulation and Data Processing for Ultrasonic Phased-Arrays Applications

    Science.gov (United States)

    Chaffaï-Gargouri, S.; Chatillon, S.; Mahaut, S.; Le Ber, L.

    2007-03-01

    The use of phased-arrays techniques has considerably contributed to extend the domain of applications and the performances of ultrasonic methods on complex configurations. Their adaptability offers a great freedom for conceiving the inspection leading to a wide range of functionalities gathering electronic commutation, applications of different delay laws and so on. This advantage allows to circumvent the difficulties encountered with more classical techniques especially when the inspection is assisted by simulation at the different stages : probe design (optimization of the number and characteristics of the elements), evaluation of the performances in terms of flaw detection (zone coverage) and characterization, driving the array (computation of adapted delay laws) and finally analyzing the results (versatile model-based imaging tools allowing in particular to locate the data in the real space). The CEA is strongly involved in the development of efficient simulation-based tools adapted to these needs. In this communication we present the recent advances done at CEA in this field and show several examples of complex NDT phased arrays applications. On these cases we show the interest and the performances of simulation-helped array design, array-driving and data analysis.

  6. Preparation of a pipette tip-based molecularly imprinted solid-phase microextraction monolith by epitope approach and its application for determination of enkephalins in human cerebrospinal fluid.

    Science.gov (United States)

    Li, Hua; Li, Dan

    2015-11-10

    In this study, a novel molecularly imprinted polymer (MIP) monolith for highly selective extraction of enkephalins was synthesized and prepared in a micropipette tip using epitope imprinting technique. The synthesized MIPs were characterized by scanning electron microscope (SEM) and infrared spectroscopy. A molecularly imprinted solid-phase microextraction (MISPME) method was developed for extraction of enkephalins in aqueous solutions. The parameters affecting MISPME were optimized. The results indicated that this MIP monolith exhibited specific recognition capability, high enrichment efficiency and excellent reusability for enkephalins. MALDI-TOF MS analysis demonstrated that this MIP monolith can act as a useful tool for highly selective purification and enrichment of enkephalin, a kind of low abundance protein, from high-abundance proteins in human cerebrospinal fluids (CSF). Employed this MIP monolith as solid-phase microextraction column, quantitative assay of enkephalins in human CSF was developed by HPLC-ultraviolet (UV) detection in this work. The detection limits were 0.05-0.08nM. This MISPME/HPLC-UV method was used to quantify Met-enkephalin and Leu-enkephalin levels in the CSF of patients with cancer pain.

  7. A 220 GHz reflection-type phased array concept study

    Science.gov (United States)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2011-05-01

    The goal of this project is to enable light-weight, durable, and portable systems capable of performing standoff detection of person-borne improvised explosive devices (PB-IEDs) through the development of millimeter-wave reflection-type phased arrays. Electronic beam steering eliminates the need for complex mechanical scanners that are commonly implemented with millimeter-wave imaging systems and would reduce overall system size and weight. We present a concept study of a 220 GHz reflection-type phased array for the purpose of performing beam scanning of a confocal reflector system. Requirements for effective imaging of the desired target region are established, including spatial resolution, total scan angle, and number of image pixels achievable. We examine the effects of array architecture on beam characteristics as it is scanned off broadside, including Gaussicity and encircled energy. Benchmark requirements are determined and compared with the capabilities of several potential phase shifter technologies, including MEMS-based variable capacitor phase shifters, switches, and varactor diode-based phase shifters.

  8. Airborne ultrasonic phased arrays using ferroelectrets: a new fabrication approach.

    Science.gov (United States)

    Ealo, Joao L; Camacho, Jorge J; Fritsch, Carlos

    2009-04-01

    In this work, a novel procedure that considerably simplifies the fabrication process of ferroelectret-based multielement array transducers is proposed and evaluated. Also, the potential of ferroelectrets being used as active material for air-coupled ultrasonic transducer design is demonstrated. The new construction method of multi-element transducers introduces 2 distinctive improvements. First, active ferroelectret material is not discretized into elements, and second, the need of structuring upper and/or lower electrodes in advance of the permanent polarization of the film is removed. The aperture discretization and the mechanical connection are achieved in one step using a through-thickness conductive tape. To validate the procedure, 2 linear array prototypes of 32 elements, with a pitch of 3.43 mm and a wide usable frequency range from 30 to 300 kHz, were built and evaluated using a commercial phased-array system. A low crosstalk among elements, below -30 dB, was measured by interferometry. Likewise, a homogeneous response of the array elements, with a maximum deviation of +/-1.8 dB, was obtained. Acoustic beam steering measurements were accomplished at different deflection angles using a calibrated microphone. The ultrasonic beam parameters, namely, lateral resolution, side lobe level, grating lobes, and focus depth, were congruent with theory. Acoustic images of a single reflector were obtained using one of the array elements as the receiver. Resulting images are also in accordance with numerical simulation, demonstrating the feasibility of using these arrays in pulse-echo mode. The proposed procedure simplifies the manufacturing of multidimensional arrays with arbitrary shape elements and not uniformly distributed. Furthermore, this concept can be extended to nonflat arrays as long as the transducer substrate conforms to a developable surface.

  9. Scan blindness in infinite phased arrays of printed dipoles

    Science.gov (United States)

    Pozar, D. M.; Schaubert, D. H.

    1984-01-01

    A comprehensive study of infinite phased arrays of printed dipole antennas is presented, with emphasis on the scan blindness phenomenon. A rigorous and efficient moment method procedure is used to calculate the array impedance versus scan angle. Data are presented for the input reflection coefficient for various element spacings and substrate parameters. A simple theory, based on coupling from Floquet modes to surface wave modes on the substrate, is shown to predict the occurrence of scan blindness. Measurements from a waveguide simulator of a blindness condition confirm the theory.

  10. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T., E-mail: katou.frme.8180@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Yamamoto, S. [Kobe City College of Technology, 8-3, Gakuenhigashimati, Nishi-ku, Kobe-shi, Hyougo 651-2194 (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

    2013-01-21

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm{sup 2} and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×10{sup 5} at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu,Y){sub 2}(SiO{sub 4})O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm{sup 3} crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm{sup 2} pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a {sup 137}Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET). -- Highlights: ► We developed a newly designed large-area monolithic MPPC array. ► We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. ► We fabricated gamma-ray camera consisting of the MPPC array and submillimeter pixelized LYSO and GGAG scintillators. ► In

  11. SAR processing with stepped chirps and phased array antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  12. Preparation of a hierarchically porous AlPO4 monolith via an epoxide-mediated sol–gel process accompanied by phase separation

    Directory of Open Access Journals (Sweden)

    Wenyan Li, Yang Zhu, Xingzhong Guo, Kazuki Nakanishi, Kazuyoshi Kanamori and Hui Yang

    2013-01-01

    Full Text Available Monolithic aluminum phosphate (AlPO4 with a macro–mesoporous structure has been successfully prepared via the sol–gel process accompanied by phase separation in the presence of poly(ethylene oxide (PEO. Gelation of the system has been mediated by propylene oxide (PO, while PEO induces a phase separation. The dried gel is amorphous, whereas the crystalline tridymite phase precipitates upon heating above 1000 °C. Heat treatment does not spoil the macroporous morphology of the AlPO4 monoliths. Nitrogen adsorption–desorption measurements revealed that the skeletons of the dried gels possess a mesostructure with a median pore size of about 30 nm and a surface area as high as 120 m2 g−1. Hydrothermal treatment before heat treatment can increase the surface area to 282 m2 g−1.

  13. Preparation of a hierarchically porous AlPO4 monolith via an epoxide-mediated sol-gel process accompanied by phase separation

    Science.gov (United States)

    Li, Wenyan; Zhu, Yang; Guo, Xingzhong; Nakanishi, Kazuki; Kanamori, Kazuyoshi; Yang, Hui

    2013-08-01

    Monolithic aluminum phosphate (AlPO4) with a macro-mesoporous structure has been successfully prepared via the sol-gel process accompanied by phase separation in the presence of poly(ethylene oxide) (PEO). Gelation of the system has been mediated by propylene oxide (PO), while PEO induces a phase separation. The dried gel is amorphous, whereas the crystalline tridymite phase precipitates upon heating above 1000 °C. Heat treatment does not spoil the macroporous morphology of the AlPO4 monoliths. Nitrogen adsorption-desorption measurements revealed that the skeletons of the dried gels possess a mesostructure with a median pore size of about 30 nm and a surface area as high as 120 m2 g-1. Hydrothermal treatment before heat treatment can increase the surface area to 282 m2 g-1.

  14. Extraction of amphetamines and methylenedioxyamphetamines from urine using a monolithic silica disk-packed spin column and high-performance liquid chromatography-diode array detection.

    Science.gov (United States)

    Namera, Akira; Nakamoto, Akihiro; Nishida, Manami; Saito, Takeshi; Kishiyama, Izumi; Miyazaki, Shota; Yahata, Midori; Yashiki, Mikio; Nagao, Masataka

    2008-10-24

    To overcome the limitations of solid-phase extraction, we developed a device comprising a spin column packed with octadecyl silane-bonded monolithic silica for extracting amphetamines and methylenedioxyamphetamines from urine. Urine (0.5mL), buffer (0.4mL), and methoxyphenamine (internal standard) were directly put into the preactivated column. The column was centrifuged (3000rpm, 5min) for sample loading and washed. The adsorbed analytes were eluted and analyzed by high-performance liquid chromatography, without evaporation. The results were as follows: linear curves (drug concentrations of 0.2-20microg/mL); correlation coefficients >0.99; detection limit, 0.1microg/mL. The proposed method is not only useful for drugs from biological materials but also highly reproducible for the analysis of these drugs in urine.

  15. Monolithic spectrometer

    Science.gov (United States)

    Rajic, Slobodan; Egert, Charles M.; Kahl, William K.; Snyder, Jr., William B.; Evans, III, Boyd M.; Marlar, Troy A.; Cunningham, Joseph P.

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  16. Directional spectrum of ocean waves from array measurements using phase/time/path difference methods

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A.; Sarma, Y.V.B.; Menon, H.B.

    Wave direction has for the first time been consistently, accurately and unambiguously evaluated from array measurements using the phase/time/path difference (PTPD) methods of Esteva in case of polygonal arrays and Borgman in case of linear arrays...

  17. Brazilian Decimetre Array (Phase-1): Initial solar observations

    Science.gov (United States)

    Ramesh, R.; Sawant, H. S.; Cecatto, J. R.; Faria, C.; Fernandes, F. C. R.; Kathiravan, C.; Suryanarayana, G. S.

    An East-West one-dimensional radio interferometer array consisting of 5 parabolic dish antennas has been set-up at Cachoeira Paulista, Brazil (Longitude: 45°0'20″W, Latitude: 22°41'19″S) for observations of Sun and some of the strong sidereal sources by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-1 of the proposed Brazilian Decimetre Array (BDA) and can be operated at any frequency in the range 1.2-1.7 GHz. The instrument is functional since November 2004 onwards at 1.6 GHz. The angular and temporal resolution at the above frequency range are ˜3' and 100 ms, respectively. We present here the initial solar observations carried out with this array.

  18. Optically addressed ultra-wideband phased antenna array

    Science.gov (United States)

    Bai, Jian

    Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization

  19. An FPGA based Phased Array Processor for the Sub-Millimeter Array

    CERN Document Server

    Nagpal, Vinayak

    2012-01-01

    It has been widely acknowledged that Very Long Baseline Interferometry (VLBI) in the submillimeter wavelengths can make imaging observations of super massive black holes possible. The Sub-Millimeter Array (SMA) along with the James Clerk Maxwell Telescope (JCMT) and Caltech Submillimeter Observatory (CSO) on the Mauna Kea summit in Hawaii can together provide a large collecting area as one or more stations for VLBI observations aimed at studying an event horizon. To work as a VLBI station with full collecting area the SMA (or a combination SMA, JCMT, CSO antennas) would need a processor to enable phased array operation. This masters project focusses on building such a processor. Back end processing for high bandwidth radio telescopes has traditionally been done using custom designed application specific integrated circuits (ASIC). Recent advances in Field Programmable Gate Array (FPGA) technology have made FPGAs both powerful and economically viable for radio astronomy back ends. We have attempted to take adv...

  20. AlGaAs phased array laser for optical communications

    Science.gov (United States)

    Carlson, N. W.

    1989-01-01

    Phased locked arrays of multiple AlGaAs diode laser emitters were investigated both in edge emitting and surface emitting configurations. CSP edge emitter structures, coupled by either evanescent waves or Y-guides, could not achieve the required powers (greater than or similar to 500 mW) while maintaining a diffraction limited, single lobed output beam. Indeed, although the diffraction limit was achieved in this type of device, it was at low powers and in the double lobed radiation pattern characteristic of out-of-phase coupling. Grating surface emitting (GSE) arrays were, therefore, investigated with more promising results. The incorporation of second order gratings in distribute Bragg reflector (DBR) structures allows surface emission, and can be configured to allow injection locking and lateral coupling to populate 2-D arrays that should be able to reach power levels commensurate with the needs of high performance, free space optical communications levels. Also, a new amplitude modulation scheme was developed for GSE array operation.

  1. Penicillin analyses by capillary electrochromatography-mass spectrometry with different charged poly(stearyl methacrylate-divinylbenzene) monoliths as stationary phases.

    Science.gov (United States)

    Liu, Wan-Ling; Wu, Ching-Yi; Li, Yi-Ting; Huang, Hsi-Ya

    2012-11-15

    This study describes the ability of an on-line concentration capillary electrochromatography (CEC) coupled with mass spectrometry (MS) for the determination of eight common penicillin antibiotics. Poly(stearyl methacrylate-divinylbenzene) (poly(SMA-DVB)) based monolithic columns prepared under the same conditions but differing only in the charged monomer were used as separation columns. Vinylbenzyl trimethylammonium chloride (VBTA) and vinylbenzenesulfonate (VBSA) were employed as the positively charged monolith and negatively charged monolith, respectively. Results indicated that poly(SMA-DVB-VBTA) monolithic column provided reproducible performance for penicillin separation through ion-exchange interaction, while the negatively charged poly(SMA-DVB-VBSA) column produced unstable separation due to the electrostatic repulsion between the electrophilic analytes and the negatively charged stationary phase. On-line concentration steps of step-gradient elution combined with anion selective injection (ASEI) were used to enhance the detection sensitivity of the CEC-MS method and all penicillin detection sensitivities were further improved (reduction in the limits of detection from 1.9-31 μg/L (normal injection mode) to 0.05-0.2 μg/L (on-line concentration mode)). Finally, this optimal on-line concentration CEC-MS method was applied to trace penicillin analyses in milk samples.

  2. Preparation and application of a novel molecularly imprinted solid-phase microextraction monolith for selective enrichment of cholecystokinin neuropeptides in human cerebrospinal fluid.

    Science.gov (United States)

    Ji, Xiang; Li, Dan; Li, Hua

    2015-08-01

    A novel molecularly imprinted polymer (MIP) monolith for highly selective extraction of cholecystokinin (CCK) neuropeptides was prepared in a micropipette tip. The MIPs were synthesized by epitope imprinting technique and the polymerization conditions were investigated and optimized. The synthesized MIPs were characterized by infrared spectroscopy, elemental analyzer and scanning electron microscope. A molecularly imprinted solid-phase microextraction (MI-μ-SPE) method was developed for the extraction of CCK neuropeptides in aqueous solutions. The parameters affecting MI-μ-SPE were optimized. The results indicated that this MIP monolith exhibited specific recognition capability and high enrichment efficiency for CCK neuropeptides. In addition, it showed excellent reusability. This MIP monolith was used for desalting and enrichment of CCK4, CCK5 and CCK8 from human cerebrospinal fluid prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis, and the results show that this MIP monolith can be a useful tool for effective purification and highly selective enrichment of multiple homologous CCK neuropeptides in cerebrospinal fluid simultaneously. By employing MI-μ-SPE combined with HPLC-ESI-MS/MS analysis, endogenous CCK4 in human cerebrospinal fluid was quantified.

  3. Fabrication of a polymeric ionic liquid-based adsorbent for multiple monolithic fiber solid-phase microextraction of endocrine disrupting chemicals in complicated samples.

    Science.gov (United States)

    Pei, Miao; Zhang, Zirui; Huang, Xiaojia; Wu, Yuanfei

    2017-04-01

    A multiple monolithic fiber solid-phase microextraction (MMF-SPME) utilizing polymeric ionic liquid-based adsorbent was prepared. The adsorbent was obtained by in situ copolymerization of an ionic liquid, 1-trimethyl-(4-vinylbenzyl) aminium chloride and dual cross-linkers (divinylbenzene and ethylenedimethacrylate). The effect of preparation conditions including the content of ionic liquid and porogen in the polymerization mixture on extraction performance was studied in detail. Infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry were used to inspect the physicochemical properties of the new adsorbent. The applicability of the new MMF-SPME was demonstrated by the extraction of trace endocrine disrupting chemicals (EDCs). Results indicated that the prepared MMF-SPME could extract EDCs effectively through multi-interactions such as ion-exchange, π-π and hydrophobic interactions. After optimization of extraction parameters, a method of MMF-SPME coupled to high performance liquid chromatography/diode array detection was conducted to detect trace EDCs in complicated samples including environmental water and human urine. The limits of detection (S/N=3) and quantification (S/N=10) for targeted compounds were 0.011-0.065μg/L and 0.036-0.21μg/L, respectively. Satisfactory precision was also achieved by evaluating the repeatability and intermediate precision with relative standard deviations (RSDs) of less than 9% and 10%, respectively. At the same time, the proposed method was successfully applied for the determination of EDCs in water and human urine with spiking recoveries ranged from 70.6% to 119%.

  4. The application of taylor weighting, digital phase shifters, and digital attenuators to phased-array antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Brock, Billy C.

    2008-03-01

    Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fed directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.

  5. High-internal-phase-emulsion polymeric monolith coupled with liquid chromatography-electrospray tandem mass spectrometry for enrichment and sensitive detection of trace cytokinins in plant samples.

    Science.gov (United States)

    Du, Fuyou; Sun, Lin; Zhen, Xian; Nie, Honggang; Zheng, Yanjie; Ruan, Guihua; Li, Jianping

    2015-08-01

    High-internal-phase-emulsion polymers (polyHIPEs) show great promise as solid-phase-extraction (SPE) materials because of the tremendous porosity and highly interconnected framework afforded by the high-internal-phase-emulsion (HIPE) technique. In this work, polyHIPE monolithic columns as novel SPE materials were prepared and applied to trace enrichment of cytokinins (CKs) from complex plant samples. The polyHIPE monoliths were synthesized via the in-situ polymerization of the continuous phase of a HIPE containing styrene (STY) and divinylbenzene (DVB) in a stainless column, and revealed highly efficient and selective enrichment ability for aromatic compounds. Under the optimized experimental conditions, a method using a monolithic polyHIPE column combined with liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) was developed for the simultaneous extraction and sensitive determination of trans-zeatin (tZ), meta-topolin (mT), kinetin (K), and kinetin riboside (KR). The proposed method had good linearity, with correlation coefficients (R (2)) from 0.9957 to 0.9984, and low detection limits (LODs, S/N = 3) in the range 2.4-47 pg mL(-1) for the four CKs. The method was successfully applied to the determination of CKs in real plant samples, and obtained good recoveries ranging from 68.8 % to 103.0 % and relative standard deviations (RSDs) lower than 16 %.

  6. Ultrasonic Phased Array Simulations of Welded Components at NASA

    Science.gov (United States)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles. Keywords: nondestructive evaluation, computational simulation, ultrasonics, weld, modeling, phased array

  7. Robotic inspection of fiber reinforced composites using phased array UT

    Science.gov (United States)

    Stetson, Jeffrey T.; De Odorico, Walter

    2014-02-01

    Ultrasound is the current NDE method of choice to inspect large fiber reinforced airframe structures. Over the last 15 years Cartesian based scanning machines using conventional ultrasound techniques have been employed by all airframe OEMs and their top tier suppliers to perform these inspections. Technical advances in both computing power and commercially available, multi-axis robots now facilitate a new generation of scanning machines. These machines use multiple end effector tools taking full advantage of phased array ultrasound technologies yielding substantial improvements in inspection quality and productivity. This paper outlines the general architecture for these new robotic scanning systems as well as details the variety of ultrasonic techniques available for use with them including advances such as wide area phased array scanning and sound field adaptation for non-flat, non-parallel surfaces.

  8. Phase Cascade Bridge Rectifier Array in a 2-D lattice

    CERN Document Server

    Nazari, M; Hong, M K; Mohanty, P; Erramilli, S; Narayan, O

    2016-01-01

    We report on a novel rectification phenomenon in a 2-D lattice network consisting of $N\\times N$ sites with diode and AC source elements with controllable phases. A phase cascade configuration is described in which the current ripple in a load resistor goes to zero in the large $N$ limit, enhancing the rectification efficiency without requiring any external capacitor or inductor based filters. The integrated modular configuration is qualitatively different from conventional rectenna arrays in which the source, rectifier and filter systems are physically disjoint. Exact analytical results derived using idealized diodes are compared to a realistic simulation of commercially available diodes. Our results on nonlinear networks of source-rectifier arrays are potentially of interest to a fast evolving field of distributed power networks.

  9. Monolithic microwave integrated circuits

    Science.gov (United States)

    Pucel, R. A.

    Monolithic microwave integrated circuits (MMICs), a new microwave technology which is expected to exert a profound influence on microwave circuit designs for future military systems as well as for the commercial and consumer markets, is discussed. The book contains an historical discussion followed by a comprehensive review presenting the current status in the field. The general topics of the volume are: design considerations, materials and processing considerations, monolithic circuit applications, and CAD, measurement, and packaging techniques. All phases of MMIC technology are covered, from design to testing.

  10. Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

    Science.gov (United States)

    Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

    2009-01-01

    A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

  11. Comparison of Two Detection Combination Algorithms for Phased Array Radars

    Science.gov (United States)

    2015-07-01

    weapon guidance. It can also be used effectively for secure communications [1]. In an MFR, the radar surveillance plays a critical role to optimize the...horizon/surface search, detection confirmation, multi-target tracking and cued search. The simulated radar has an aperture of 1 m2. The antennas...Comparison of Two Detection Combination Algorithms for Phased Array Radars Zhen Ding and Peter Moo Wide Area Surveillance Radar Group Radar

  12. Ultrabroadband Phased-Array Receivers Based on Optical Techniques

    Science.gov (United States)

    2016-02-26

    AFRL-AFOSR-VA-TR-2016-0121 Ultrabroadband Phased-array Receivers Based on Optical Techniques Christopher Schuetz UNIVERSITY OF DELAWARE Final Report...NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University of Delaware 210 Hullihen Hall Newark, DE 19716 8. PERFORMING ORGANIZATION...Rev. 8/98) Prescribed by ANSI Std . Z39.18 Adobe Professional 7.0 Reset INSTRUCTIONS FOR COMPLETING SF 298 1. REPORT DATE. Full publication date

  13. Early Phase Observations of the KVN+VERA Joint Array

    CERN Document Server

    Sawada-Satoh, S

    2013-01-01

    The KVN+VERA array is a joint VLBI project of seven VLBI stations spread throughout Korea and Japan. Since the first fringe detection in 2008, the early phase observations of the KVN+VERA have been carried out every several months. Currently, two observing bands of 22 and 43 GHz are available. We are aiming for early realization of science observations with the 1-Gbps recording system from 2012.

  14. Command and Control for Multifunction Phased Array Radar

    OpenAIRE

    Weber, Mark E.; Cho, John Y. N.; Thomas, Henry G

    2017-01-01

    We discuss the challenge of managing the Multifunction Phased Array Radar (MPAR) timeline to satisfy the requirements of its multiple missions, with a particular focus on weather surveillance. This command and control (C2) function partitions the available scan time among these missions, exploits opportunities to service multiple missions simultaneously, and utilizes techniques for increasing scan rate where feasible. After reviewing the candidate MPAR architectures and relevant previous rese...

  15. Phased-array radar design application of radar fundamentals

    CERN Document Server

    Jeffrey, Thomas

    2009-01-01

    Phased-Array Radar Design is a text-reference designed for electrical engineering graduate students in colleges and universities as well as for corporate in-house training programs for radar design engineers, especially systems engineers and analysts who would like to gain hands-on, practical knowledge and skills in radar design fundamentals, advanced radar concepts, trade-offs for radar design and radar performance analysis.

  16. Phases in a General Chaotic Three-Coupled-Laser Array

    Institute of Scientific and Technical Information of China (English)

    ZHOU Liang; DUAN Kai-Liang

    2012-01-01

    Phases in a general chaotic three-coupled-laser array are numerically investigated.Phase attractors are firstly found to exist within corresponding basins of attraction on the projection plane of phase differences of the threecoupled-laser array.Whether the chaos appears or not is related not only to the coupling strength but also to the initial phase differences.For a large coupling strength new phase attractors can occur.With the increase of coupling strength,the three-coupled-laser array has a great chance of resulting in a quiescent to chaotic state.Based on these results,we present the method to reach phase-locking when the coupling strength is strong.%The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS). Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204, THz spectra of T202 and T204 show the weak broad absorption bands. Then, the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%. The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and Korea70. The quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.

  17. Large-Aperture Membrane Active Phased-Array Antennas

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  18. Automatic onset phase picking for portable seismic array observation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Automatic phase picking is a critical procedure for seismic data processing, especially for a huge amount of seismic data recorded by a large-scale portable seismic array. In this study is presented a new method used for automatic accurate onset phase picking based on the property of dense seismic array observations. In our method, the Akaike's information criterion (AIC) for the single channel observation and the least-squares cross-correlation for the multi-channel observation are combined together. The tests by the seismic array observation data after triggering with the short-term average/long-term average (STA/LTA) technique show that the phase picking error is less than 0.3 s for local events by using the single channel AIC algorithm. In terms of multi-channel least-squares cross-correlation technique, the clear teleseismic P onset can be detected reliably. Even for the teleseismic records with high noise level, our algorithm is also able to effectually avoid manual misdetections.

  19. PATL: A RFID Tag Localization based on Phased Array Antenna

    Science.gov (United States)

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-01-01

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags’ number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area. PMID:28295014

  20. Monolithic integration of a silicon nanowire field-effect transistors array on a complementary metal-oxide semiconductor chip for biochemical sensor applications.

    Science.gov (United States)

    Livi, Paolo; Kwiat, Moria; Shadmani, Amir; Pevzner, Alexander; Navarra, Giulio; Rothe, Jörg; Stettler, Alexander; Chen, Yihui; Patolsky, Fernando; Hierlemann, Andreas

    2015-10-06

    We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs.

  1. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Science.gov (United States)

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

    2013-01-01

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm2 and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×105 at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400 kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu, Y)2(SiO4)O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm3 crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22 ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd3Ga3Al2O12 (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm2 pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a 137Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET).

  2. Investigation of ultrasonic phased array inspection of a planar crack using finite element method

    OpenAIRE

    Mardani Kharat, Mostafa; Sodagar,Sina; Rashed, G. R.

    2012-01-01

    International audience; The characteristics of the ultrasonic field radiated by a linear phased array transducer and the echo information of the inspected area are the main basis of designing a phased array inspection system. In this paper, a theoretical investigation is accomplished on the ultrasonic wave diffraction using the ultrasonic phased array method for evaluation of the planar cracks. For this purpose, the ultrasonic wave field resulting from a phased array transducer and its intera...

  3. Preparation and characterization of silica monolith modified with bovine serum albumin-gold nanoparticles conjugates and its use as chiral stationary phases for capillary electrochromatography.

    Science.gov (United States)

    Lu, Junyu; Ye, Fanggui; Zhang, Aizhu; Wei, Zong; Peng, Yan; Zhao, Shulin

    2011-08-01

    This paper describes the development of silica monolith modified with bovine serum albumin-gold nanoparticles (BSA-GNPs) conjugates as chiral stationary phases for capillary electrochromatography (CEC). The bare monolithic silica column was prepared by a sol-gel process and has been modified chemically with 3-mercaptopropyltrimethoxysilane to provide thiol groups, followed by immobilization of gold nanoparticles via the formation of an Au-S bond and modification with BSA as the chiral selector via the nitrogen lone pair of electrons. It has been demonstrated that the monolithic chiral stationary phases can be used for the enantioseparation of a number of phenylthiocarbamyl amino acids (PTC-D/L-AAs) by CEC. Ten pairs of tested amino acids enantiomers were successfully resolved within 18 min under optimized conditions, and the resolution values were in the range of 1.486-2.083. With PTC-D/L-tryptophan used as the probe solute, the influences of applied voltage, organic modifier and buffer pH in mobile phase on apparent retention factor, enantioselectivity and resolution factor were also investigated.

  4. On-chip optical phase locking of single growth monolithically integrated Slotted Fabry Perot lasers.

    Science.gov (United States)

    Morrissey, P E; Cotter, W; Goulding, D; Kelleher, B; Osborne, S; Yang, H; O'Callaghan, J; Roycroft, B; Corbett, B; Peters, F H

    2013-07-15

    This work investigates the optical phase locking performance of Slotted Fabry Perot (SFP) lasers and develops an integrated variable phase locked system on chip for the first time to our knowledge using these lasers. Stable phase locking is demonstrated between two SFP lasers coupled on chip via a variable gain waveguide section. The two lasers are biased differently, one just above the threshold current of the device with the other at three times this value. The coupling between the lasers can be controlled using the variable gain section which can act as a variable optical attenuator or amplifier depending on bias. Using this, the width of the stable phase locking region on chip is shown to be variable.

  5. Preparation of low flow-resistant methacrylate-based monolithic stationary phases of different hydrophobicity and the application to rapid reversed-phase liquid chromatographic separation of alkylbenzenes at high flow rate and elevated temperature.

    Science.gov (United States)

    Ueki, Yuji; Umemura, Tomonari; Iwashita, Yoshikazu; Odake, Tamao; Haraguchi, Hiroki; Tsunoda, Kin-ichi

    2006-02-17

    Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 microm i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below approximately 0.4 MPa at a normal linear velocity of 1mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20 cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature.

  6. An application of ultrasonic phased array imaging in electron beam welding inspection

    Institute of Scientific and Technical Information of China (English)

    周琦; 刘方军; 李志军; 李旭东; 齐铂金

    2002-01-01

    The basic principle and features of ultrasonic phased array imaging are discussed in this paper. Through the ultrasonic phased array technology, the electron beam welding defects and frozen keyholes characterization and imaging were realized. The ultrasonic phased array technology can detect kinds of defects in electron beam welding (EBW) quickly and easily.

  7. Development of Automatic Phased Array Inspection System for Long-distance Pipeline

    Institute of Scientific and Technical Information of China (English)

    XueZhenkui; BaiShiwu; ZhanHua; XiaXin; XiangYang

    2004-01-01

    In the paper the development of phased array technique home and abroad is summarized, the overall structure and main research on phased array inspection system are introduced, and meanwhile the future field of study and development of phased array ultrasonic inspection technique is pointed out.

  8. Physical and chemical sensing using monolithic semiconductor optical transducers

    Science.gov (United States)

    Zappe, Hans P.; Hofstetter, Daniel; Maisenhoelder, Bernd; Moser, Michael; Riel, Peter; Kunz, Rino E.

    1997-09-01

    We present two monolithically integrated optical sensor systems based on semiconductor photonic integrated circuits. These compact, robust and highly functional transducers perform all necessary optical and electro-optical functions on-chip; extension to multi-sensor arrays is easily envisaged. A monolithic Michelson interferometer for high-resolution displacement measurement and a monolithic Mach-Zehnder interferometer for refractometry are discussed.

  9. Innovative phased array ultrasonic inspection solution for large rotor shafts

    Energy Technology Data Exchange (ETDEWEB)

    Maes, G.; Devos, D.; Tremblay, P., E-mail: gmaes@zetec.com [Zetec, Ville de Quebec, Quebec (Canada)

    2016-05-15

    The increasing needs of energy production led to new rotor shaft designs with larger dimensions. A new generation of nuclear power plants is already being deployed worldwide with such heavy components. Their implementation requires new inspection tools in order to guarantee the public safety and to ensure the quality of these critical parts. Due to the long sound path, conventional ultrasonic (UT) techniques cannot provide adequate detectability of the reference reflectors required by the existing codes. Also, some standards require multiple angle beams to be applied in addition to the straight beam inspection, and this leads to long inspection times. This paper will address the implementation and validation of phased array (PA) UT techniques, using a semi-flexible 2D array probe, for the inspection of large mono-block rotor shaft forgings. It will show how the beam focusing and steering capabilities of phased array UT probes can be used to overcome the issues occurring with conventional UT probes. Results of acoustic beam simulation, as well as detectability measurements and data acquisitions on representative test specimens will be presented and compared with conventional UT performance. Various aspects of the hardware and software specification will be addressed, as well as the potential reduction of the total inspection time. (author)

  10. Dual-Polarized Planar Phased Array Analysis for Meteorological Applications

    Directory of Open Access Journals (Sweden)

    Chen Pang

    2015-01-01

    Full Text Available This paper presents a theoretical analysis for the accuracy requirements of the planar polarimetric phased array radar (PPPAR in meteorological applications. Among many factors that contribute to the polarimetric biases, four factors are considered and analyzed in this study, namely, the polarization distortion due to the intrinsic limitation of a dual-polarized antenna element, the antenna pattern measurement error, the entire array patterns, and the imperfect horizontal and vertical channels. Two operation modes, the alternately transmitting and simultaneously receiving (ATSR mode and the simultaneously transmitting and simultaneously receiving (STSR mode, are discussed. For each mode, the polarimetric biases are formulated. As the STSR mode with orthogonal waveforms is similar to the ATSR mode, the analysis is mainly focused on the ATSR mode and the impacts of the bias sources on the measurement of polarimetric variables are investigated through Monte Carlo simulations. Some insights of the accuracy requirements are obtained and summarized.

  11. Supersymmetric phase transition in Josephson-tunnel-junction arrays

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1988-08-31

    The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T/sub I/less than or equal toT/sub V/, then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T/sub I/=T/sub V/. Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory.

  12. A novel hybrid metal-organic framework-polymeric monolith for solid-phase microextraction.

    Science.gov (United States)

    Lin, Chen-Lan; Lirio, Stephen; Chen, Ya-Ting; Lin, Chia-Her; Huang, Hsi-Ya

    2014-03-17

    This study describes the fabrication of a novel hybrid metal-organic framework- organic polymer (MOF-polymer) for use as a stationary phase in fritless solid-phase microextraction (SPME) for validating analytical methods. The MOF-polymer was prepared by using ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and an imidazolium-based ionic liquid as porogenic solvent followed by microwave-assisted polymerization with the addition of 25 % MOF. This novel hybrid MOF-polymer was used to extract penicillin (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) under different conditions. Quantitative analysis of the extracted penicillin samples using the MOF-organic polymer for SPME was conducted by using capillary electrochromatography (CEC) coupled with UV analysis. The penicillin recovery was 63-96.2 % with high reproducibility, sensitivity, and reusability. The extraction time with the proposed fabricated SPME was only 34 min.

  13. A Monolithic Radiation-Pressure Driven, Low Phase Noise Silicon Nitride Opto-Mechanical Oscillator

    CERN Document Server

    Tallur, Siddharth; Bhave, Sunil A

    2011-01-01

    Cavity opto-mechanics enabled radiation pressure (RP) driven oscillators shown in the past offer an all optical Radio Frequency (RF) source without the need for external electrical feedback. However these oscillators require external tapered fiber or prism coupling and non-standard fabrication processes. In this work, we present a CMOS compatible fabrication process to design high optical quality factor opto-mechanical resonators in silicon nitride. The ring resonators designed in this process demonstrate low phase noise RP driven oscillations. Using integrated grating couplers and waveguide to couple light to the micro-resonator eliminates 1/f^3 and other higher order phase noise slopes at close-to-carrier frequencies present in previous demonstrations. We present an RP driven OMO operating at 41.97MHz with a signal power of -11dBm and phase noise of -85dBc/Hz at 1kHz offset with only 1/f^2 noise down to 10Hz offset from carrier.

  14. Phased Array Ultrasonic Evaluation of Space Shuttle Main Engine (SSME) Nozzle Weld

    Science.gov (United States)

    James, Steve; Engel, J.; Kimbrough, D.; Suits, M.; Hopson, George (Technical Monitor)

    2001-01-01

    This viewgraph presentation gives an overview of the phased array ultrasonic evaluation of the Space Shuttle Main Engine (SSME) nozzle weld. Details are given on the nondestructive testing evaluation approach, conventional shear wave and phased array techniques, and an x-ray versus phased array risk analysis. The field set-up was duplicated to the greatest extent possible in the laboratory and the phased array ultrasonic technique was developed and validated prior to weld evaluation. Results are shown for the phased array ultrasonic evaluation and conventional ultrasonic evaluation results.

  15. Modeling the radiation of ultrasonic phased-array transducers with Gaussian beams.

    Science.gov (United States)

    Huang, Ruiju; Schmerr, Lester W; Sedov, Alexander

    2008-12-01

    A new transducer beam model, called a multi-Gaussian array beam model, is developed to simulate the wave fields radiated by ultrasonic phased-array transducers. This new model overcomes the restrictions on using ordinary multi-Gaussian beam models developed for large single-element transducers in phased-array applications. It is demonstrated that this new beam model can effectively model the steered and focused beams of a linear phased-array transducer.

  16. Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules

    Science.gov (United States)

    Gouda, Ayman A.; Hashem, Hisham; Jira, Thomas

    2014-09-01

    Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40 °C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080 ± 0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (λmax: 520 nm) or amaranth dye (λmax: 530 nm). The reacted oxidant corresponds to the drug content. Beer’s law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 μg mL-1 for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL-1 and 0.782, 0.973 and 0.376 μg mL-1 for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them.

  17. Resolving phase ambiguities in the calibration of redundant interferometric arrays: implications for array design

    Science.gov (United States)

    Kurien, Binoy G.; Tarokh, Vahid; Rachlin, Yaron; Shah, Vinay N.; Ashcom, Jonathan B.

    2016-10-01

    We provide new results enabling robust interferometric image reconstruction in the presence of unknown aperture piston variation via the technique of redundant spacing calibration (RSC). The RSC technique uses redundant measurements of the same interferometric baseline with different pairs of apertures to reveal the piston variation among these pairs. In both optical and radio interferometry, the presence of phase-wrapping ambiguities in the measurements is a fundamental issue that needs to be addressed for reliable image reconstruction. In this paper, we show that these ambiguities affect recently developed RSC phasor-based reconstruction approaches operating on the complex visibilities, as well as traditional phase-based approaches operating on their logarithm. We also derive new sufficient conditions for an interferometric array to be immune to these ambiguities in the sense that their effect can be rendered benign in image reconstruction. This property, which we call wrap-invariance, has implications for the reliability of imaging via classical three-baseline phase closures as well as generalized closures. We show that wrap-invariance is conferred upon arrays whose interferometric graph satisfies a certain cycle-free condition. For cases in which this condition is not satisfied, a simple algorithm is provided for identifying those graph cycles which prevent its satisfaction. We apply this algorithm to diagnose and correct a member of a pattern family popular in the literature.

  18. Ultrasonic Phased Array Inspection Simulations of Welded Components at NASA

    Science.gov (United States)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increased role in the future for nondestructive evaluation in order to better understand the physics of the inspection process and help explain the experimental results. It will also help to prove or disprove the feasibility for an inspection method or inspection scenario, help optimize inspections, and allow to a first approximation limits of detectability. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

  19. Phased array ultrasonic inspection of feeder welds - regulatory perspective

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, B.; Kirkhope, K.; Colligan, L.; Valpy, B.; Stevenson, J. [Canadian Nuclear Safety Commission, Ottawa, Ontario (Canada)

    2011-07-01

    The Canadian Nuclear Safety Commission has accepted the application of Phased Array Ultrasonic Testing (PAUT) in lieu of Radiographic Testing for feeder piping replacement at the Point Lepreau and Bruce A Units 1 and 2 refurbishment projects. Background information regarding the principles and elements of the CNSC regulatory approach for the acceptance of PAUT for feeder installation will be discussed, addressing quality management and regulatory oversight activities focused on inspection reliability and dose reduction. CNSC staff's views for future direction on the application of PAUT in lieu of RT in regulatory framework and codes and standards are also discussed. (author)

  20. Wide-band residual phase-noise measurements on 40-GHz monolithic mode-locked lasers

    DEFF Research Database (Denmark)

    Larsson, David; Hvam, Jørn Märcher

    2005-01-01

    We have performed wide-band residual phase-noise measurements on semiconductor 40-GHz mode-locked lasers by employing electrical waveguide components for the radio-frequency circuit. The intrinsic timing jitters of lasers with one, two, and three quantum wells (QW) are compared and our design...... prediction, concerning noise versus number of QWs, for the first time corroborated by experiments. A minimum jitter of 44 fs is found, by extrapolating to the Nyquist frequency, for the one-QW device having nearly transform-limited pulses of 1.2 ps. This jitter is nearly three times lower than for a three...

  1. Determination of urinary 8-hydroxy-2′-deoxyguanosine by capillary electrophoresis with molecularly imprinted monolith in-tube solid phase microextraction

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Urinary 8-hydroxy-2'-deoxyguanosine(8-OHdG) is an excellent marker of oxidative DNA damage.In this study,employing guanosine as dummy template a novel molecularly imprinted(MIP) monolithic capillary column had been synthesized,and that was used as medium of in-tube solid phase microextraction(SPME).Coupled with capillary electrophoresis-electrochemical detection(CE-ECD),the system of extraction and detection of 8-OHdG in urinary sample had been developed.Because of its greater phase ratio combined with c...

  2. CryoPAF4: a cryogenic phased array feed design

    Science.gov (United States)

    Locke, Lisa; Garcia, Dominic; Halman, Mark; Henke, Doug; Hovey, Gary; Jiang, Nianhua; Knee, Lewis; Lacy, Gordon; Loop, David; Rupen, Michael; Veidt, Bruce; Wierzbicki, Ramunas

    2016-07-01

    Phased array feed (PAF) receivers used on radio astronomy telescopes offer the promise of increased fields of view while maintaining the superlative performance attained with traditional single pixel feeds (SPFs). However, the much higher noise temperatures of room temperature PAFs compared to cryogenically-cooled SPFs have prevented their general adoption. Here we describe a conceptual design for a cryogenically cooled 2.8 - 5.18 GHz dual linear polarization PAF with estimated receiver temperature of 11 K. The cryogenic PAF receiver will comprise a 140 element Vivaldi antenna array and low-noise amplifiers housed in a 480 mm diameter cylindrical dewar covered with a RF transparent radome. A broadband two-section coaxial feed is integrated within each metal antenna element to withstand the cryogenic environment and to provide a 50 ohm impedance for connection to the rest of the receiver. The planned digital beamformer performs digitization, frequency band selection, beam forming and array covariance matrix calibration. Coupling to a 15 m offset Gregorian dual-reflector telescope, cryoPAF4 can expect to form 18 overlapping beams increasing the field of view by a factor of 8x compared to a single pixel receiver of equal system temperature.

  3. Improved SNR of phased-array PERES coils via simulation study

    Energy Technology Data Exchange (ETDEWEB)

    RodrIguez, Alfredo O [Centro de Investigacion en Imagenologia e Instrumentacion Medica, Universidad Autonoma Metropolitana Iztapalapa, Av. San Rafael Atlixco 186, Mexico, DF, 09340 (Mexico); Medina, LucIa [DISCA, Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, AP 20-728, Admo. No. 20, 01000 Mexico, DF (Mexico); Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, DF (Mexico)

    2005-09-21

    A computational comparison of signal-to-noise ratio (SNR) was performed between a conventional phased array of two circular-shaped coils and a petal resonator surface array. The quasi-static model and phased-array optimum SNR were combined to derive an SNR formula for each array. Analysis of mutual inductance between coil petals was carried out to compute the optimal coil separation and optimum number of petal coils. Mutual interaction between coil arrays was not included in the model because this does not drastically affect coil performance. Phased arrays of PERES coils show a 114% improvement in SNR over that of the simplest circular configuration. (note)

  4. Performance of a monolithic LaBr{sub 3}:Ce crystal coupled to an array of silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ulyanov, Alexei, E-mail: alexey.uliyanov@ucd.ie [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Morris, Oran [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Department of Computer Science & Applied Physics, Galway-Mayo Institute of Technology, Galway (Ireland); Hanlon, Lorraine; McBreen, Sheila; Foley, Suzanne; Roberts, Oliver J.; Tobin, Isaac; Murphy, David; Wade, Colin [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Nelms, Nick; Shortt, Brian [European Space Agency, ESTEC, 2200 AG Noordwijk (Netherlands); Slavicek, Tomas; Granja, Carlos; Solar, Michael [Institute of Experimental and Applied Physics, Czech Technical University in Prague, 12800 Prague 2 (Czech Republic)

    2016-02-21

    A gamma-ray detector composed of a single 28×28×20 mm{sup 3} LaBr{sub 3}:Ce crystal coupled to a custom built 4×4 array of silicon photomultipliers was tested over an energy range of 30 keV to 9.3 MeV. The silicon photomultipliers were initially calibrated using 20 ns light pulses generated by a light emitting diode. The photodetector responses measured as a function of the number of incident photons were found to be non-linear and consistent with model predictions. Using corrections for the non-linearity of the silicon photomultipliers, the detector showed a linear response to gamma-rays with energies from 100 keV to the maximum available energy of 9.3 MeV. The energy resolution was found to be 4% FWHM at 662 keV. Despite the large thickness of the scintillator (20 mm) and a 5 mm thick optical window, the detector was capable of measuring the positions of the gamma-ray interaction points. The position resolution was measured at 356 keV and was found to be 8 mm FWHM in the detector plane and 11 mm FWHM for the depth of interaction. The detector can be used as a building block of a larger calorimeter system that is capable of measuring gamma-ray energies up to tens of MeV.

  5. Optically controlled phased-array antenna with PSK communications

    Science.gov (United States)

    Cooper, Martin J.; Sample, Peter; Lewis, Meirion F.; Wilson, Rebecca A.

    2004-11-01

    An optically controlled RF/microwave/mm-wave phased array antenna has been developed operating at 10 GHz with 30 kHz reconfiguration rate via the use of a micromachined silicon Spatial Light Modulator. A communications function has been demonstrated with a variety of Phase Shift Keying modulation schemes (BPSK, QPSK, MSK) at data rates up to 200 Mbit/s and low BER (<1×10-9). A single channel has been demonstrated at 35 GHz. The properties of photonic components are taken advantage of in several ways: (i) since the carrier frequency is derived from heterodyning of lasers, it is tuneable from almost DC-100 GHz, (ii) the use of optical fiber allows for EMI immune antenna remoting, and (iii) the wide information bandwidth of optical modulators, which in this configuration is carrier frequency independent. The above is achieved in a lightweight and compact format, with considerable scope for further reductions in size and weight.

  6. Phased array tuning for optimal ultrasonic guided wave mode selection

    Science.gov (United States)

    Bostron, J. H.; Rose, J. L.; Moose, C. A.

    2014-02-01

    Ultrasonic guided waves have become widely used in a variety of nondestructive evaluation applications due to their efficiency in defect detection, ability to inspect hidden areas, and other reasons. With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection. An "optimal" mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. In this work, we consider the use of guided interface waves for bond evaluation. A phased comb array transducer is used to sweep in the phase velocity - frequency space in an effort to determine optimal modes.

  7. Cylindrical Antenna With Partly Adaptive Phased-Array Feed

    Science.gov (United States)

    Hussein, Ziad; Hilland, Jeff

    2003-01-01

    A proposed design for a phased-array fed cylindrical-reflector microwave antenna would enable enhancement of the radiation pattern through partially adaptive amplitude and phase control of its edge radiating feed elements. Antennas based on this design concept would be attractive for use in radar (especially synthetic-aperture radar) and other systems that could exploit electronic directional scanning and in which there are requirements for specially shaped radiation patterns, including ones with low side lobes. One notable advantage of this design concept is that the transmitter/ receiver modules feeding all the elements except the edge ones could be identical and, as a result, the antenna would cost less than in the cases of prior design concepts in which these elements may not be identical.

  8. An Optimal Beamforming Algorithm for Phased-Array Antennas Used in Multi-Beam Spaceborne Radiometers

    DEFF Research Database (Denmark)

    Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.;

    2015-01-01

    Strict requirements for future spaceborne ocean missions using multi-beam radiometers call for new antenna technologies, such as digital beamforming phased arrays. In this paper, we present an optimal beamforming algorithm for phased-array antenna systems designed to operate as focal plane arrays...

  9. Online micro-solid-phase extraction based on boronate affinity monolithic column coupled with high-performance liquid chromatography for the determination of monoamine neurotransmitters in human urine.

    Science.gov (United States)

    Yang, Xiaoting; Hu, Yufei; Li, Gongke

    2014-05-16

    Quantification of monoamine neurotransmitters is very important in diagnosing and monitoring of patients with neurological disorders. We developed an online analytical method to selectively determine urinary monoamine neurotransmitters, which coupled the boronate affinity monolithic column micro-solid-phase extraction with high-performance liquid chromatography (HPLC). The boronate affinity monolithic column was prepared by in situ polymerization of vinylphenylboronic acid (VPBA) and N,N'-methylenebisacrylamide (MBAA) in a stainless capillary column. The prepared monolithic column showed good permeability, high extraction selectivity and capacity. The column-to-column reproducibility was satisfactory and the enrichment factors were 17-243 for four monoamine neurotransmitters. Parameters that influence the online extraction efficiency, including pH of sample solution, flow rate of extraction and desorption, extraction volume and desorption volume were investigated. Under the optimized conditions, the developed method exhibited low limit of detection (0.06-0.80μg/L), good linearity (with R(2) between 0.9979 and 0.9993). The recoveries in urine samples were 81.0-105.5% for four monoamine neurotransmitters with intra- and inter-day RSDs of 2.1-8.2% and 3.7-10.6%, respectively. The online analytical method was sensitive, accurate, selective, reliable and applicable to analysis of trace monoamine neurotransmitters in human urine sample.

  10. Monolithic molecularly imprinted solid-phase extraction for the selective determination of trace cytokinins in plant samples with liquid chromatography-electrospray tandem mass spectrometry.

    Science.gov (United States)

    Du, Fuyou; Ruan, Guihua; Liang, Shenghua; Xie, Fuwei; Liu, Huwei

    2012-08-01

    Cytokinins (CTKs) are a class of growth-regulating hormones involved in various physiological and developmental processes. More novel analytical methods for the accurate identification and quantitative determination of trace CTKs in plants have been desired to better elucidate the roles of CTKs. In this work, a novel method based on monolithic molecularly imprinted solid-phase extraction followed by liquid chromatography-electrospray tandem mass spectrometry (mMI-SPE-LC-MS/MS) was developed for accurate determination of four CTKs in plant samples. The molecularly imprinted polymer monolith was prepared by using kinetin as the template in syringes and exhibited specific recognition ability for the four CTKs in comparison with that of non-imprinted polymer monolith. Several factors affecting the extraction performance of mMI-SPE, including the pH of loading sample solution, the nature and volume of elution solvent, the flow rate of sample loading, and sample volume, were investigated, respectively. Under the optimized conditions, the proposed mMI-SPE-LC-MS/MS method was successfully applied in the selective extraction and determination of four CTKs in plant tissues, and it offers detection limits (S/N = 3) of 104, 113, 130, and 89 pg/mL and mean recoveries of 85.9%, 79.3%, 73.5%, and 70.1% for kinetin, kinetin glucoside, trans-zeatin, and meta-topolin (mT), respectively, with the corresponding RSDs less than 15%.

  11. Fast analysis of glycosides based on HKUST-1-coated monolith solid-phase microextraction and direct analysis in real-time mass spectrometry.

    Science.gov (United States)

    Li, Xianjiang; Wang, Xin; Ma, Wen; Ai, Wanpeng; Bai, Yu; Ding, Li; Liu, Huwei

    2017-04-01

    Glycosides are a kind of highly important natural aromatic precursors in tobacco leaves. In this study, a novel HKUST-1-coated monolith dip-it sampler was designed for the fast and sensitive analysis of trace glycosides using direct analysis in real-time mass spectrometry. This device was prepared in two steps: in situ polymerization of monolith in a glass capillary of dip-it and layer-by-layer growth of HKUST-1 on the surface of monolith. Sufficient extraction was realized by immersing the tip to solution and in situ desorption was carried out by plasma direct analysis in real time. Compared with traditional solid-phase microextraction protocols, sample desorption was not needed anymore, and only extraction conditions were needed to be optimized in this method, including the gas temperature of direct analysis in real time, extraction time, and CH3 COONH4 additive concentration. This method enabled the simultaneous detection of six kinds of glycosides with the limits of detection of 0.02-0.05 μg/mL and the linear ranges covering two orders of magnitude with the limits of quantitation of 0.05-0.1 μg/mL. Moreover, the developed method was applied for the glycosides analysis of three tobacco samples, which only took about 2 s for every sample.

  12. Preoperative rectal cancer staging with phased-array MR

    Directory of Open Access Journals (Sweden)

    Giusti Sabina

    2012-03-01

    Full Text Available Abstract Background We retrospectively reviewed magnetic resonance (MR images of 96 patients with diagnosis of rectal cancer to evaluate tumour stage (T stage, involvement of mesorectal fascia (MRF, and nodal metastasis (N stage. Our gold standard was histopathology. Methods All studies were performed with 1.5-T MR system (Symphony; Siemens Medical System, Erlangen, Germany by using a phased-array coil. Our population was subdivided into two groups: the first one, formed by patients at T1-T2-T3, N0, M0 stage, whose underwent MR before surgery; the second group included patients at Tx N1 M0 and T3-T4 Nx M0 stage, whose underwent preoperative MR before neoadjuvant chemoradiation therapy and again 4-6 wks after the end of the treatment for the re-staging of disease. Our gold standard was histopathology. Results MR showed 81% overall agreement with histological findings for T and N stage prediction; for T stage, this rate increased up to 95% for pts of group I (48/96, while for group II (48/96 it decreased to 75%. Preoperative MR prediction of histologically involved MRF resulted very accurate (sensitivity 100%; specificity 100% also after chemoradiation (sensitivity 100%; specificity 67%. Conclusions Phased-array MRI was able to clearly estimate the entire mesorectal fat and surrounding pelvic structures resulting the ideal technique for local preoperative rectal cancer staging.

  13. PZT Network and Phased Array Lamb Wave Based SHM Systems

    Energy Technology Data Exchange (ETDEWEB)

    Silva, C [Academia da Forca Aerea, Granja do Marques, 2715-021 Pero Pinheiro (Portugal); Rocha, B; Suleman, A, E-mail: cbsilva@emfa.pt [University of Victoria, Department of Mechanical Engineering, PO Box 3055, Stn.CSC, Victoria, BC, V8W 3P6 (Canada)

    2011-07-19

    With the application of newer materials, such as composite materials, and growing complexity and capacity of current aircraft structures, reliably and completely assess the condition of the total structures in real time is then of growing and utmost importance. PZT Network and Phased Array, Lamb wave based Structural Health Monitoring (SHM) systems were developed to be applied to thin panels. The selection of transducers, their size and selected locations for their installation are described. The development and selection of the signal generation and data acquisition systems is also presented in detail. The requirements conducing to the development and selection of these systems are laid and particularly the selection of the actuation signal applied is justified. The development of a damage detection algorithm based in the comparison of the current structural state to a reference state is described, to detect damage reflected Lamb waves. Such method was implemented in software and integrated in the SHM system developed. Subsequently the detection algorithm, based in discrete signals correlation, was further improved by incorporating statistical methods. For phased arrays, a novel damage location algorithm is presented based on the individual sensors response. A visualization method based concurrently in the statistical methods developed and superposition of the different results obtained from a test set was implemented. These tests conducted to the successful and repeatable detection of 1mm damages in a multiple damaged plate with great confidence. Finally, a brief comparison and a hybrid system implementation is presented.

  14. Square Kilometre Array: a concept design for Phase 1

    CERN Document Server

    Garrett, M A; Deboer, D R; Jonas, J L; Rawlings, S; Schilizzi, R T

    2010-01-01

    The SKA at mid and low frequencies will be constructed in two distinct phases, the first being a subset of the second. This document defines the main scientific goals and baseline technical concept for the SKA Phase 1 (SKA_1). The major science goals for SKA_1 will be to study the history and role of neutral Hydrogen in the Universe from the dark ages to the present-day, and to employ pulsars as probes of fundamental physics. The baseline technical concept of SKA_1 will include a sparse aperture array operating at frequencies up to 450 MHz, and an array of dishes, initially operating at frequencies up to 3 GHz but capable of 10 GHz in terms of antenna surface accuracy. An associated Advanced Instrumentation Program (AIP) allows further development of new technologies currently under investigation. Construction will take place in 2016-2019 at a total capital cost of 350M\\texteuro, including an element for contingency. The cost estimates of the SKA_1 telescope are now the subject of a more detailed and thorough...

  15. ALGORITHMS FOR TRACKING MANEUVERING TARGET WITH PHASED ARRAY RADAR

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Several typical algorithms for tracking maneuvering target with phased array radar are studied in this paper. The constant gain filter with multiple models is analyzed. A typical method for adaptively controlling the sampling interval is modified. The performance of the single model and multiple model estimator with uniform and variable sampling interval are evaluated and compared. It is shown by the simulation results that it is necessary to apply the adaptive sampling policy based on the multiple model method when the maneuvering targets are tracked by the phased array radar since saving radar resources is more important. The adaptive algorithms of variable sampling interval are better than the algorithms of variable model. The adaptive policy to determine the sampling interval based on multiple model are superior than those based on the single-model filter, because IMM estimator can adapt to the maneuver more quickly and the prediction covariance of IMM is the more sensitive and more reliable index than residual to determine the sampling interval. With IMM-based method, lower sampling interval is required for a certain accuracy.

  16. Optimization of electro-optic phase shifters for integrated optical phased arrays

    Science.gov (United States)

    Macik, Dwayne D.; Bravo, Tyler E.; Pentecost, Seeley M.; Espinal, Francisco A.; Madsen, Christi K.

    2017-05-01

    A low-loss, high-speed optical phased array (OPA) has been designed and fabricated. Two different platforms have been utilized in combination to leverage electro-optic (EO) tuning. A lithium niobate (LiNbO3) optical phased array was fabricated and used in conjunction with a silicon nitride (Si3N4) 8x8 waveguide array that condenses the output pitch and utilizes the TriplexTM waveguide technology. This OPA allows for the non-mechanical beam steering (NMBS) of 1550 nm light on an edge coupled optic platform and takes advantage of the high electro-optic coefficient and high speed capability of LiNbO3 for electro-optic phase tuning. This coupled OPA has an overall insertion loss of 3.5 dB which is advantageous to silicon-on-insulator OPAs that have shown overall insertion losses of 14 dB. To characterize and tune this device, a 3 lens imaging system was employed to produce both near- and far- field intensity patterns of the output of the OPA on a static image plane. At the image plane, a high resolution infrared camera was used to observe the resulting intensity pattern. The control software for tuning the OPA reads the intensity incident at a specified position on the detector array, and has a PWM interface to drive the electro-optic phase controls. Beam steering was accomplished using an iterative tuning algorithm.

  17. RCS estimation of linear and planar dipole phased arrays approximate model

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    In this book, the RCS of a parallel-fed linear and planar dipole array is derived using an approximate method. The signal propagation within the phased array system determines the radar cross section (RCS) of phased array. The reflection and transmission coefficients for a signal at different levels of the phased-in scattering array system depend on the impedance mismatch and the design parameters. Moreover the mutual coupling effect in between the antenna elements is an important factor. A phased array system comprises of radiating elements followed by phase shifters, couplers, and terminating load impedance. These components lead to respective impedances towards the incoming signal that travels through them before reaching receive port of the array system. In this book, the RCS is approximated in terms of array factor, neglecting the phase terms. The mutual coupling effect is taken into account. The dependence of the RCS pattern on the design parameters is analyzed. The approximate model is established as a...

  18. Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Haiyun, E-mail: zhaihaiyun@126.com [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China); Su, Zihao [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China); Chen, Zuanguang, E-mail: chenzg@mail.sysu.edu.cn [School of Pharmaceutical Science, Sun Yat-sen University, Guangzhou 510006 (China); Liu, Zhenping; Yuan, Kaisong; Huang, Lu [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China)

    2015-03-20

    Highlights: • A new GO-MISPE monolithic capillary column was prepared. • The column showed ability of impurities removal and excellent selectivity. • Phloxine B existed in real sample was enriched more than 90 times. • The GO-MISPE column presented good recovery and high stability. • The method was prospered to analyze phloxine B and LOD achieved 0.3 ng g{sup −1}. - Abstract: A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC–LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001–2.0 μg mL{sup −1} (r = 0.9995) with the detection limit (S/N = 3) of 0.075 ng mL{sup −1}. Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC–LIF method can be applied to sensitively determine phloxine B in coffee bean.

  19. Optimizing an ELF/VLF Phased Array at HAARP

    Science.gov (United States)

    Fujimaru, S.; Moore, R. C.

    2013-12-01

    The goal of this study is to maximize the amplitude of 1-5 kHz ELF/VLF waves generated by ionospheric HF heating and measured at a ground-based ELF/VLF receiver. The optimization makes use of experimental observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) Observatory in Gakona, Alaska. During these experiments, the amplitude, phase, and propagation delay of the ELF/VLF waves were carefully measured. The HF beam was aimed at 15 degrees zenith angle in 8 different azimuthal directions, equally spaced in a circle, while broadcasting a 3.25 MHz (X-mode) signal that was amplitude modulated (square wave) with a linear frequency-time chirp between 1 and 5 kHz. The experimental observations are used to provide reference amplitudes, phases, and propagation delays for ELF/VLF waves generated at these specific locations. The presented optimization accounts for the trade-off between duty cycle, heated area, and the distributed nature of the source region in order to construct a "most efficient" phased array. The amplitudes and phases generated by modulated heating at each location are combined in post-processing to find an optimal combination of duty cycle, heating location, and heating order.

  20. Phase Closure at 691 GHz using the Submillimeter Array

    CERN Document Server

    Hunter, T R; Peck, A B; Christensen, R D; Blundell, R; Camacho, A; Patt, F; Sakamoto, K; Young, K H

    2007-01-01

    Phase closure at 682 GHz and 691 GHz was first achieved using three antennas of the Submillimeter Array (SMA) interferometer located on Mauna Kea, Hawaii. Initially, phase closure was demonstrated at 682.5 GHz on Sept. 19, 2002 using an artificial ground-based "beacon" signal. Subsequently, astronomical detections of both Saturn and Uranus were made at the frequency of the CO(6-5) transition (691.473 GHz) on all three baselines on Sept. 22, 2002. While the larger planets such as Saturn are heavily resolved even on these short baselines (25.2m, 25.2m and 16.4m), phase closure was achieved on Uranus and Callisto. This was the first successful experiment to obtain phase closure in this frequency band. The CO(6-5) line was also detected towards Orion BN/KL and other Galactic sources, as was the vibrationally-excited 658 GHz water maser line toward evolved stars. We present these historic detections, as well as the first arcsecond-scale images obtained in this frequency band.

  1. A passive synthetic aperture phase correction algorithm for the asymmetric twin-line array sonar

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A passive synthetic aperture based on phase correction algorithm for solving the port-starboard discrimination problem in the non-aligned towed twin-line array sonar, is described. This method creates a virtual array through applying the estimated phase correction into one array of twin-line arrays. Because the synthetic virtual array is aligned with the other array in twin-line arrays, the right port-starboard discriminated results can be obtained by array processing based on the new synthetic twin-line array. The effect of proposed method has been shown by simulated and sea-trials results in towed twin-line array sonar. With low extra computational loads, the proposed method is easy to apply to the practice.

  2. Monolithic silica-based capillary reversed-phase liquid chromatography/electrospray mass spectrometry for plant metabolomics

    NARCIS (Netherlands)

    Tolstikov, V.V.; Lommen, A.; Nakanishi, K.; Tanaka, N.; Fiehn, O.

    2003-01-01

    Application of C18 monolithic silica capillary columns in HPLC coupled to ion trap mass spectrometry detection was studied for probing the metabolome of the model plant Arabidopsis thaliana. It could be shown that the use of a long capillary column is an easy and effective approach to reduce ionizat

  3. Phased-MIMO Radar: A Tradeoff Between Phased-Array and MIMO Radars

    CERN Document Server

    Hassanien, Aboulnasr

    2009-01-01

    We propose a new technique for multiple-input multiple-output (MIMO) radar with colocated antennas which we call phased-MIMO radar. The new technique enjoys the advantages of MIMO radar without sacrificing the main advantage of phased-array radar which is the coherent processing gain at the transmitting side. The essence of the proposed technique is to partition the transmitting array into a number of subarrays that are allowed to overlap. Then, each subarray is used to coherently transmit a waveform which is orthogonal to the waveforms transmitted by other subarrays. Coherent processing gain can be achieved by designing a weight vector for each subarray to form a beam towards a certain direction in space. Moreover, the subarrays are combined jointly to form a MIMO radar resulting in higher resolution capabilities. The substantial improvements offered by the proposed phased-MIMO radar technique as compared to previous techniques are demonstrated analytically and by simulations through analysis of the correspo...

  4. Phased array beamforming and imaging in composite laminates using guided waves

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

    2016-04-01

    This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple simulated defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple simulated defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  5. Slow and fast light in SOA-EA structures for phased-array antennas

    DEFF Research Database (Denmark)

    Sales, S.; Öhman, Filip; Bermejo, A.;

    We present an SOA-EA structure for controlling the phase and amplitude of optically fed phased-array antennas. Phase shifts of 40 degrees are obtained through slow and fast light effects by changing only the reverse voltage.......We present an SOA-EA structure for controlling the phase and amplitude of optically fed phased-array antennas. Phase shifts of 40 degrees are obtained through slow and fast light effects by changing only the reverse voltage....

  6. AIN Monolithic Microchannel Cooled Heatsink for High Power Laser Diode Array%应用于大功率激光二极管列阵的单片集成微通道制冷热沉

    Institute of Scientific and Technical Information of China (English)

    马杰慧; 方高瞻; 蓝永生; 马骁宇

    2005-01-01

    介绍了一种应用于大功率激光二极管列阵的新型单片集成微通道制冷热沉.这种热沉已制造并经过测试.10叠层的激光二极管列阵的热阻为0.121℃/W.相邻两个激光条的间距是1.17mm.在20%高占空比条件下,波长为808nm左右,峰值功率可以达到611W.%A novel AIN monolithic microchannel cooled heatsink for high power laser diode array is introduced.The high power stack laser diode array with an AIN monolithic microchannel heatsink is fabricated and tested.The thermal impedance of a 10 stack laser diode array is 0.121℃/W.The pitch between two adjacent bars is 1.17mm.The power level of 611W is achieved under the 20% duty factor condition at an emission wavelength around 808nm.

  7. Randomly phase-locked microlaser arrays and fuzzy eigenmodes with stochastic phasing.

    Science.gov (United States)

    Riyopoulos, S

    2006-10-30

    Deviations in the cold cavity parameters, random or systematic, produce incoherently phased-locked laser arrays with unevenly distributed phase difference and intensity. The collective radiation fields constitute "fuzzy" eigenmodes; the phasing among cavities is constant in time but changes randomly from site-to-site. The existence and structure of such eigenmodes is demonstrated numerically and analyzed theoretically using the rate equations for coupled semiconductor laser cavities. Active coupling, whereby one cavity's radiation field modulates the complex gain of nearby cavities (cross-cavity hole burning), is essential for the frequency pulling allowing synchronization of the laser operating frequencies.

  8. Preparation and applications of monolithic structures containing metal-organic frameworks.

    Science.gov (United States)

    Lv, Yongqin; Tan, Xinyi; Svec, Frantisek

    2017-01-01

    Metal-organic frameworks are a new category of advanced porous materials with large surface areas and porosities, uniform pore sizes, tunable surface chemistry, and structural diversity. In combination with monoliths, they allow the fine tuning of desired interactions required in a variety of applications. This review article summarizes results of recent studies focused on synthetic strategies enabling incorporation of metal-organic frameworks in monolithic structures. A diverse array of applications including chromatographic separation, solid-phase microextraction, sample enrichment, heterogeneous catalysis, and enzymatic catalysis are also described. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Evolutionary Design of a Phased Array Antenna Element

    Science.gov (United States)

    Globus, Al; Linden, Derek; Lohn, Jason

    2006-01-01

    We present an evolved S-band phased array antenna element design that meets the requirements of NASA's TDRS-C communications satellite scheduled for launch early next decade. The original specification called for two types of elements, one for receive only and one for transmit/receive. We were able to evolve a single element design that meets both specifications thereby simplifying the antenna and reducing testing and integration costs. The highest performance antenna found using a genetic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results are largely consistent with simulation. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years its computer speed has increased and electromagnetic simulators have improved. Many antenna types have been investigated, including wire antennas, antenna arrays and quadrifilar helical antennas. In particular, our laboratory evolved a wire antenna design for NASA's Space Technology 5 (ST5) spacecraft. This antenna has been fabricated, tested, and is scheduled for launch on the three spacecraft in 2006.

  10. Phased array ultrasonic processing for enhanced and affordable diagnosis

    Science.gov (United States)

    Dominguez, N.; Rougeron, G.; Leberre, S.; Pautel, R.

    2013-01-01

    Phased array ultrasonic reconstruction techniques are often presented as a prospect for better and enhanced diagnosis. However to date few applications of these techniques can be found in the industry, partly because of questions on sizing but also because they often require heavy acquisitions. A way forward is then to propose techniques requiring less intensive data acquisition to make them broadly affordable in practice. Several approaches ranging from full matrix capture to paintbrush acquisitions are presented in this paper in combination with associated reconstruction processing like the Total Focusing Method (TFM) and the Time Domain Topological Energy (TDTE) techniques. Emphasis is given to their relative relevancies and practical applicability on typical configurations of interest for industries. The paper also presents recent efforts made on the acceleration of processing computation times, in particular through the use of GPU architectures.

  11. Monitoring Growth of Closed Fatigue Crack Using Subharmonic Phased Array

    Science.gov (United States)

    Ohara, Y.; Endo, H.; Hashimoto, M.; Shintaku, Y.; Yamanaka, K.

    2010-02-01

    To ensure the safety and reliability of atomic power plants and airplanes, the technique of monitoring closed fatigue cracks is requisite. Here we monitored the distribution of the crack depths and closure behavior in the length direction after 48000 and 87000 fatigue cycles using subharmonic phased array for crack evaluation (SPACE). The crack depths in the subharmonic images were larger than those in the fundamental images. Specifically, the difference was larger at near the side surface than at the center. The percentage of the closed part varied with the crack growth in the specimen. In addition, we fabricated shoe for SPACE to facilitate mechanical scanning. Thus, it was demonstrated that SPACE is useful in monitoring closed fatigue crack growth.

  12. Reverse Phase Protein Arrays for High-throughput Toxicity Screening

    DEFF Research Database (Denmark)

    Pedersen, Marlene Lemvig; Block, Ines; List, Markus

    High-throughput screening is extensively applied for identification of drug targets and drug discovery and recently it found entry into toxicity testing. Reverse phase protein arrays (RPPAs) are used widespread for quantification of protein markers. We reasoned that RPPAs also can be utilized...... beneficially in automated high-throughput toxicity testing. An advantage of using RPPAs is that, in addition to the baseline toxicity readout, they allow testing of multiple markers of toxicity, such as inflammatory responses, which do not necessarily cumulate in cell death. We used transfection of si...... a robotic screening platform. Furthermore, we automated sample tracking and data analysis by developing a bundled bioinformatics tool named “MIRACLE”. Automation and RPPA-based viability/toxicity readouts enable rapid testing of large sample numbers, while granting the possibility for flexible consecutive...

  13. Monolithic metal-organic framework MIL-53(Al)-polymethacrylate composite column for the reversed-phase capillary liquid chromatography separation of small aromatics.

    Science.gov (United States)

    Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

    2016-03-01

    A monolithic capillary column containing a composite of metal-organic framework MIL-53(Al) incorporated into hexyl methacrylate-co-ethylene dimethacrylate was prepared to enhance the separation of mixtures of small aromatic compounds by using capillary liquid chromatography. The addition of 10 mg/mL MIL-53(Al) microparticles increased the micropore content in the monolithic matrix and increased the Brunauer-Emmett-Teller surface area from 26.92 to 85.12 m(2) /g. The presence of 1,4-benzenedicarboxylate moieties within the structure of MIL-53(Al) as an organic linker greatly influenced the separation of aromatic mixtures through π-π interactions. High-resolution separation was obtained for a series of alkylbenzenes (with resolution factors in the range 0.96-1.75) in less than 8 min, with 14 710 plates/m efficiency for propylbenzene, using a binary polar mobile phase of water/acetonitrile in isocratic mode. A reversed-phase separation mechanism was indicated by the increased retention factor and resolution as the water percentage in the mobile phase increased. A stability study on the composite column showed excellent mechanical stability under various conditions. The higher resolution and faster separation observed at increased temperature indicated an exothermic separation, whereas the negative values for the free energy change of transfer indicated a spontaneous process.

  14. Development of an X-Band Coupled-Oscillator Transmit/Receive Phased Array

    Science.gov (United States)

    Venkatesan, J.; Pogorzelski, R.

    2007-08-01

    The development of an 8.4 GHz (X-band) coupled-oscillator phased array employing full-duplex transmit and receive capability is described. Attractive features of phased arrays for deep-space communication include enabling high-data-rate communication and providing low-mass electronic beam steering. The coupled-oscillator phased-array concept seeks to reduce the cost and power consumption incurred in a conventional phased array by simplifying the beam-steering mechanism of the array. In this article, the overall system-level architecture of a full-duplex transmit and receive coupled-oscillator array is described, and the progress made in designing various specific components of a linear 1 x 7 coupled-oscillator array is also detailed.

  15. Conversion of out-of-phase to in-phase order in coupled laser arrays with second harmonics

    CERN Document Server

    Tradonsky, Chene; Ronen, Eitan; Pal, Vishwa; Chriki, Ronen; Friesem, Asher A; Davidson, Nir

    2015-01-01

    A novel method for converting an array of out-of-phase lasers into one of in-phase lasers that can be tightly focused is presented. The method exploits second harmonic generation and can be adapted for different laser arrays geometries. Experimental and calculated results, presented for negatively coupled lasers formed in a square, honeycomb, and triangular geometries are in good agreement.

  16. Airborne electronically steerable phased array. [steerable antennas - systems analysis

    Science.gov (United States)

    Coats, R.

    1975-01-01

    Results of a study directed to the design of a lightweight high-gain, spaceborne communications array are presented. The array includes simultaneous transmission and receiving, automatic acquisition and tracking of a signal within a 60-degree cone from the array normal, and provides for independent forming of the transmit and receive beams. Application for this array is the space shuttle, space station, or any of the advanced manned (or unmanned) orbital vehicles. Performance specifications are also given.

  17. Comprehensive profiling of ribonucleosides modification by affinity zirconium oxide-silica composite monolithic column online solid-phase microextraction - Mass spectrometry analysis.

    Science.gov (United States)

    Jiang, Han-Peng; Chu, Jie-Mei; Lan, Meng-Dan; Liu, Ping; Yang, Na; Zheng, Fang; Yuan, Bi-Feng; Feng, Yu-Qi

    2016-09-02

    More than 140 modified ribonucleosides have been identified in RNA. Determination of endogenous modified ribonucleosides in biological fluids may serve as non-invasive disease diagnostic strategy. However, detection of the modified ribonucleosides in biological fluids is challenging, especially for the low abundant modified ribonucleosides due to the serious matrix interferences of biological fluids. Here, we developed a facile preparation strategy and successfully synthesized zirconium oxide-silica (ZrO2/SiO2) composite capillary monolithic column that exhibited excellent performance for the selective enrichment of cis-diol-containing compounds. Compared with the boronate-based affinity monolith, the ZrO2/SiO2 monolith showed ∼2 orders of magnitude higher extraction capacity and can be used under physiological pH (pH 6.5-7.5). Using the prepared ZrO2/SiO2 composite monolith as the trapping column and reversed-phase C18 column as the analytical column, we further established an online solid-phase microextraction (SPME) in combination with liquid chromatography-mass spectrometry (online SPME-LC-MS/MS) analysis for the comprehensive profiling of ribonucleosides modification in human urine. Our results showed that 68 cis-diol-containing ribosylated compounds were identified in human urine, which is, to the best of our knowledge, the highest numbers of cis-diol-containing compounds were determined in a single analysis. It is worth noting that four modified ribonucleosides were discovered in the human urine for the first time. In addition, the quantification results from the pooled urine samples showed that compared to healthy controls, the contents of sixteen ribose conjugates in the urine of gastric cancer, eleven in esophagus cancer and seven in lymphoma increased more than two folds. Among these ribose conjugates, four ribose conjugates increased more than two folds in both gastric cancer and esophagus cancer; three ribose conjugates increased more than two

  18. Aluminum based metal-organic framework-polymer monolith in solid-phase microextraction of penicillins in river water and milk samples.

    Science.gov (United States)

    Lirio, Stephen; Liu, Wan-Ling; Lin, Chen-Lan; Lin, Chia-Her; Huang, Hsi-Ya

    2016-01-08

    In this study, aluminum based metal-organic framework (Al-MOF)-organic polymer monoliths were prepared via microwave-assisted polymerization of ethylene dimethacrylate (EDMA), butyl methacrylate (BMA) with different weight percentages of Al-MOF (MIL-53; 37.5-62.5%) and subsequently utilized as sorbent in solid-phase microextraction (SPME) of penicillins (penicillin G, penicillin V, oxacillin, cloxacillin, dicloxacillin, nafcillin). The Al-MOF-polymer was characterized using Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and SEM-energy-dispersive X-ray spectroscopy (SEM-EDS) to clarify the retained crystalline structure well as the homogeneous dispersion of Al-MOF (MIL-53) in polymer monolith. The developed Al-MOF-polymer (MIL-53) monolithic column was evaluated according to its extraction recovery of penicillins. Several parameters affecting the extraction recoveries of penicillins using fabricated Al-MOF-polymer (MIL-53) monolithic column including different MIL-53 weight percentages, column length, pH, desorption solvent, and mobile phase flow rate were investigated. For comparison, different Al-based MOFs (MIL-68, CYCU-4 and DUT-5) were fabricated using the optimized condition for MIL-53-polymer (sample matrix at pH 3, 200μL desorption volume using methanol, 37.5% of MOF, 4-cm column length at 0.100mLmin(-1) flow rate). Among all the Al-MOF-polymers, MIL-53(Al)-polymer still afforded the best extraction recovery for penicillins ranging from 90.5 to 95.7% for intra-day with less than 3.5% relative standard deviations (RSDs) and inter-day precision were in the range of 90.7-97.6% with less than 4.2% RSDs. Meanwhile, the recoveries for column-to-column were in the range of 89.5-93.5% (polymer was applied for the extraction of penicillin in river water and milk by spiking trace-level penicillin for as low as 50μgL(-1) and 100μgL(-1) with recoveries ranging from 80.8% to 90.9% (<6.7% RSDs) in

  19. Phase dynamics of high radiance fiber laser arrays with active phase control

    Science.gov (United States)

    Bochove, Erik; Neschke, Brendan; Nair, Niketh; Delgado, Paul; Braiman, Yehuda

    2015-03-01

    The existing model of the LOCSET technique for the active phase synchronization of fiber laser arrays (T. Shay, Opt. Express, 2006) is extended to include relevant physical properties of the system, such as inherent optical path differences (OPD), line-width and group velocity dispersion (GVD), and we also include phase "jitter" of the master oscillator's output in the model, which in experiments is implemented to induce spectral broadening for suppression of nonlinear frequency conversion. Linearization of the phase error signal, which incorrectly predicts convergence to a synchronous equilibrium state, is not performed. Instead, the closed-loop control dynamics are shown to be described by differential equations of Kuramoto type when phase corrector response dynamics are negligible. Linear stability analysis indicates that there is always one and no more than one dynamically stable state. The latter is shown to be normally synchronous, except when strong "jitter" is applied. A Liapounov function is found as subject to the validity of certain symmetry conditions.

  20. Determination of imidazole derivatives by micellar electrokinetic chromatography combined with solid-phase microextraction using activated carbon-polymer monolith as adsorbent.

    Science.gov (United States)

    Shih, Yung-Han; Lirio, Stephen; Li, Chih-Keng; Liu, Wan-Ling; Huang, Hsi-Ya

    2016-01-08

    In this study, an effective method for the separation of imidazole derivatives 2-methylimidazole (2-MEI), 4- methylimidazole (4-MEI) and 2-acetyl-4-tetrahydroxybutylimidazole (THI) in caramel colors using cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-sweeping-MEKC) was developed. The limits of detection (LOD) and quantitation (LOQ) for the CSEI-sweeping-MEKC method were in the range of 4.3-80μgL(-1) and 14-270μgL(-1), respectively. Meanwhile, a rapid fabrication activated carbon-polymer (AC-polymer) monolithic column as adsorbent for solid-phase microextraction (SPME) of imidazole colors was developed. Under the optimized SPME condition, the extraction recoveries for intra-day, inter-day and column-to-column were in the range of 84.5-95.1% (<6.3% RSDs), 85.6-96.1% (<4.9% RSDs), and 81.3-96.1% (<7.1% RSDs), respectively. The LODs and LOQs of AC-polymer monolithic column combined with CSEI-sweeping-MEKC method were in the range of 33.4-60.4μgL(-1) and 111.7-201.2μgL(-1), respectively. The use of AC-polymer as SPME adsorbent demonstrated the reduction of matrix effect in food samples such as soft drink and alcoholic beverage thereby benefiting successful determination of trace-level caramel colors residues using CSEI-sweeping-MEKC method. The developed AC-polymer monolithic column can be reused for more than 30 times without any significant loss in the extraction recovery for imidazole derivatives.

  1. A novel ionic liquid-modified organic-polymer monolith as the sorbent for in-tube solid-phase microextraction of acidic food additives.

    Science.gov (United States)

    Wang, Ting-Ting; Chen, Yi-Hui; Ma, Jun-Feng; Hu, Min-Jie; Li, Ying; Fang, Jiang-Hua; Gao, Hao-Qi

    2014-08-01

    A novel ionic liquid-modified organic-polymer monolithic capillary column was prepared and used for in-tube solid-phase microextraction (SPME) of acidic food additives. The primary amino group of 1-aminopropyl-3-methylimidazolium chloride was reacted with the epoxide group of glycidyl methacrylate. The as-prepared new monomer was then copolymerized in situ with acrylamide and N,N'-methylenebisacrylamide in the presence of polyethylene glycol (PEG)-8000 and PEG-10,000 as porogens. The extraction performance of the developed monolithic sorbent was evaluated for benzoic acid, 3-hydroxybenzoic acid, cinnamic acid, 2,4-dichlorophenoxyacetic acid, and 3-(trifluoromethyl)-cinnamic acid. Such a sorbent, bearing hydrophobic and anion-exchange groups, had high extraction efficiency towards the test compounds. The adsorption capacities for the analytes dissolved in water ranged from 0.18 to 1.74 μg cm(-1). Good linear calibration curves (R(2) > 0.99) were obtained, and the limits of detection (S/N = 3) for the analytes were found to be in the range 1.2-13.5 ng mL(-1). The recoveries of five acidic food additives spiked in Coca-Cola beverage samples ranged from 85.4 % to 98.3 %, with RSD less than 6.9 %. The excellent applicability of the ionic liquid (IL)-modified monolithic column was further tested by the determination of benzoic acid content in Sprite samples, further illustrating its good potential for analyzing food additives in complex samples.

  2. Preparation and evaluation of open tubular C18-silica monolithic microcartridges for preconcentration of peptides by on-line solid phase extraction capillary electrophoresis.

    Science.gov (United States)

    Ortiz-Villanueva, Elena; Benavente, Fernando; Giménez, Estela; Yilmaz, Fatma; Sanz-Nebot, Victoria

    2014-10-10

    In this study, C18-silica monoliths were synthesized as a porous layer in open tubular capillary columns, to be cut later into microcartridges for the analysis of neuropeptides by on-line solid-phase extraction capillary electrophoresis with UV and MS detection (SPE-CE-UV and SPE-CE-MS). First, several types of C18-silica monolithic (MtC18) microcartridges were used to analyse standard solutions of five neuropeptides (i.e. dynorphin A (1-7), substance P (7-11), endomorphin 1, methionine enkephalin and [Ala]-methionine enkephalin). The MtC18 sorbents were especially selective against endomorphin 1 and substance P (7-11)). The best results in terms of sensitivity and inter-microcartridge reproducibility were achieved with the microcartridges obtained from a 10-cm open tubular capillary column with a thin monolithic coating with large through-pores (1-5μm). Run-to-run repeatability, microcartridge durability, linearity ranges and LODs were studied by MtC18-SPE-CE-MS. As expected due to their greater selectivity, the best LOD enhancement was obtained for End1 and SP (7-11) (50 times with regard to CE-MS). Finally, the suitability of the methodology for analysing biological fluids was tested with plasma samples spiked with End1 and SP (7-11). Results obtained were promising because both neuropeptides could be detected at 0.05μgmL(-1), which was almost the same concentration level as for the standard solutions (0.01μgmL(-1)).

  3. Circularly Polarized Planar Helix Phased Antenna Array for 5G Mobile Terminals

    DEFF Research Database (Denmark)

    Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

    2017-01-01

    In this paper, a planar helix mobile phased antenna array is proposed for 5th generation communication systems with operating frequency of 28GHz. The proposed array displays circular polarization in the endfire direction. Over 65 degrees of axial ratio beamwidth and 7GHz of axial ratio bandwidth...... has been achieved in the proposed design. The coverage performance of the proposed phased antenna array has also been studied by using the coverage efficiency metric. Coverage efficiency of 50 % at 5 dBi gain is achieved by the proposed phased mobile antenna array....

  4. A Phased Array Antenna Signal Processing Structure, a Method and a Computer Program Product

    NARCIS (Netherlands)

    Vliet, F.E. van; Dijk, R. van

    2011-01-01

    The invention relates to a phased array antenna signal processing structure. The structure comprises a processor that includes a digital beam forming unit for generating partial beam data from digitized samples of a set of phased array antenna elements. The processor further comprises a set of input

  5. PHASIM, a sophisticated phased array antenna software simulator implemented in MATLAB 5.2

    NARCIS (Netherlands)

    Keizer, W.P.M.N.

    1999-01-01

    A sophisticated phased array simulator software package for the design and analysis of planar phased array antennas is presented. This simulator is coded in MATLAB version 5.2. Using MATLAB, numerical engineering problems can be solved in a fraction of time of time required by programs coded in FORT

  6. Procedure for tracking manoeuvring targets with a multi-purpose phased-array radar system

    NARCIS (Netherlands)

    Navarro, A.M.

    1977-01-01

    This paper describes a tracking procedure for the FUCAS-experimental multi purpose phased array system. A phased array systems is always very complex. Upto this moment there are just a few systems, the results of experiments with those systems are not yet available. FUCAS is developed to acquire

  7. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, Jordy; Kokkeler, André B.J.; Smit, Gerard J.M.

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The syste

  8. Near field phased array DOA and range estimation of UHF RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2015-01-01

    This paper presents a near field localization system based on a phased array for UHF RFID tags. To estimate angle and range the system uses a two-dimensional MUSIC algorithm. A four channel phased array is used to experimentally verify the estimation of angle and range for an EPC gen2 tag. The

  9. Procedure for tracking manoeuvring targets with a multi-purpose phased-array radar system

    NARCIS (Netherlands)

    Navarro, A.M.

    1977-01-01

    This paper describes a tracking procedure for the FUCAS-experimental multi purpose phased array system. A phased array systems is always very complex. Upto this moment there are just a few systems, the results of experiments with those systems are not yet available. FUCAS is developed to acquire exp

  10. PHASIM, a sophisticated phased array antenna software simulator implemented in MATLAB 5.2

    NARCIS (Netherlands)

    Keizer, W.P.M.N.

    1999-01-01

    A sophisticated phased array simulator software package for the design and analysis of planar phased array antennas is presented. This simulator is coded in MATLAB version 5.2. Using MATLAB, numerical engineering problems can be solved in a fraction of time of time required by programs coded in FORT

  11. Laboratory simulation on acoustic well-logging with phased array transmitter

    Institute of Scientific and Technical Information of China (English)

    QIAOWenxiao; CHENXuelian; DUGuangsheng; FANGJun; LIGang

    2003-01-01

    Two small scale acoustic phased arrays with 4 elements have been designed and assembled in the laboratory. Experiments have been carried out with them. It is found that both directivity and radiation lobe width of the phased array can be regulated by changing the time delay between the input signals on neighboring elements. Results measured are in good agreement with those calculated. By using the phased array as an acoustic transmitter and hydrophone as a receiver, small scale acoustic well-logging simulations have been carried out both on an aluminum model well and on a concrete one. Experimental results show that, by increasing the time delay of the input signals on neighboring elements, the steered radiation angle of the phased array becomes larger and larger, and generation conditions of the refracted compressional wave and the refracted shear wave are reached successively, and the refracted compressional wave, the refracted shear wave and the Stoneley wave axe strengthened, respectively. Therefore, by choosing element spacing of a phased array and acoustic wave frequency appropriately, the main radiation lobe of the phased array can be widened to cover the first critical angle of all kinds of formations, which makes it possible to apply phased array acoustic well-logging in any formation continuously without regulating directivity of the phased array.

  12. Integrated filtering in reconfigurable planar phased-array antennas with spurious harmonic suppression

    NARCIS (Netherlands)

    Cifola, L.; Gerini, G.; Monni, S.; Berg, S. van den; Water, F. van de

    2013-01-01

    In the present work, the possibility to integrate filtering functionalities in a phased-array antenna at radiating element level is investigated. The filtenna concept has been applied to an X-band phased array of slot-fed patches. An effective strategy for the suppression of spurious harmonics, base

  13. Fully Printed High-Frequency Phased-Array Antenna on Flexible Substrate

    Science.gov (United States)

    Chen, Yihong; Lu, Xuejun

    2010-01-01

    To address the issues of flexible electronics needed for surface-to-surface, surface-to-orbit, and back-to-Earth communications necessary for manned exploration of the Moon, Mars, and beyond, a room-temperature printing process has been developed to create active, phased-array antennas (PAAs) on a flexible Kapton substrate. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proven feasible for phased-array antenna systems. The carrier mobility of an individual CNT is estimated to be at least 100,000 sq cm/V(dot)s. The CNT network in solution has carrier mobility as high as 46,770 sq cm/V(dot)s, and has a large current-density carrying capacity of approx. 1,000 mA/sq cm , which corresponds to a high carrying power of over 2,000 mW/ sq cm. Such high carrier mobility, and large current carrying capacity, allows the achievement of high-speed (>100 GHz), high-power, flexible electronic circuits that can be monolithically integrated on NASA s active phasedarray antennas for various applications, such as pressurized rovers, pressurized habitats, and spacesuits, as well as for locating beacon towers for lunar surface navigation, which will likely be performed at S-band and attached to a mobile astronaut. A fully printed 2-bit 2-element phasedarray antenna (PAA) working at 5.6 GHz, incorporating the CNT FETs as phase shifters, is demonstrated. The PAA is printed out at room temperature on 100-mm thick Kapton substrate. Four CNT FETs are printed together with microstrip time delay lines to function as a 2-bit phase shifter. The FET switch exhibits a switching speed of 0.2 ns, and works well for a 5.6-GHz RF signal. The operating frequency is measured to be 5.6 GHz, versus the state-of-the-art flexible FET operating frequency of 52 MHz. The source-drain current density is measured to be over 1,000 mA/sq cm, while the conventional organic FETs, and single carbon nanotube-based FETs, are typically in the m

  14. Evolutionary Adaptive Discovery of Phased Array Sensor Signal Identification

    Energy Technology Data Exchange (ETDEWEB)

    Timothy R. McJunkin; Milos Manic

    2011-05-01

    Tomography, used to create images of the internal properties and features of an object, from phased array ultasonics is improved through many sophisiticated methonds of post processing of data. One approach used to improve tomographic results is to prescribe the collection of more data, from different points of few so that data fusion might have a richer data set to work from. This approach can lead to rapid increase in the data needed to be stored and processed. It also does not necessarily lead to have the needed data. This article describes a novel approach to utilizing the data aquired as a basis for adapting the sensors focusing parameters to locate more precisely the features in the material: specifically, two evolutionary methods of autofocusing on a returned signal are coupled with the derivations of the forumulas for spatially locating the feature are given. Test results of the two novel methods of evolutionary based focusing (EBF) illustrate the improved signal strength and correction of the position of feature using the optimized focal timing parameters, called Focused Delay Identification (FoDI).

  15. Thermal dispersion method for an ultrasonic phased-array transducer

    Science.gov (United States)

    Choi, Euna; Lee, Wonseok; Roh, Yongrae

    2016-07-01

    When the driving voltage of an ultrasonic transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer, which can burn the patient’s skin and degrade transducer performance. In this study, the method to disperse the heat inside an ultrasonic phased-array transducer has been examined. The mechanism of temperature rise due to heat generation inside the transducer was investigated by numerical analysis and the effects of the thermal properties of the components of the transducer such as specific heat and thermal conductivity on the temperature rise were analyzed. On the basis of the results, a heat-dispersive structure was devised to reduce the temperature at the surface of the acoustic lens of the transducer. Prototype transducers were fabricated to check the efficacy of the heat-dispersive structure. By experiments, we have confirmed that the new heat-dispersive structure can reduce the internal temperature by as much as 50% in comparison with the conventional structure, which confirms the validity of the thermal dispersion mechanism developed in this work.

  16. Matrix phased array (MPA) imaging technology for resistance spot welds

    Energy Technology Data Exchange (ETDEWEB)

    Na, Jeong K.; Gleeson, Sean T. [Edison Welding Institute, 1250 Arthur E. Adams Drive, Columbus, OH 43221 (United States)

    2014-02-18

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  17. Characterization of signalling pathways by reverse phase protein arrays.

    Science.gov (United States)

    Malinowsky, Katharina; Wolff, Claudia; Schott, Christina; Becker, Karl-Friedrich

    2013-01-01

    Reverse phase protein array (RPPA) is a very suitable technique to analyze large numbers of proteins in small samples like for example tumor biopsies. Beside their small size another major hindrance for the analysis of proteins from biopsies is the extraction of proteins from formalin-fixed and paraffin-embedded (FFPE) tissues. Here we describe a protocol, allowing quantitative extraction of large numbers of proteins from FFPE tissues and their subsequent analysis by RPPA. To elucidate the role of epidermal growth factor receptor (EGFR) signalling in ovarian cancer, we analyzed 23 primary tumors and corresponding metastases for the expression of 25 proteins involved in EGFR signalling with special emphasis on epithelial-mesenchymal transition (EMT). We found a significant correlation of Snail with EGFR((Tyr1086)) and p38 MAPK((Thr180/Tyr182)) in primary ovarian carcinoma and with EGFR((Tyr1086)) in their corresponding metastases. Additionally, we showed that high expression levels of the E-cadherin repressor Snail in primary tumors combined with high expression levels of the pp38 MAPK((Thr180/Tyr182)) in metastasis lead to an increased risk for death in ovarian carcinoma patients.

  18. Spatial normalization of reverse phase protein array data.

    Directory of Open Access Journals (Sweden)

    Poorvi Kaushik

    Full Text Available Reverse phase protein arrays (RPPA are an efficient, high-throughput, cost-effective method for the quantification of specific proteins in complex biological samples. The quality of RPPA data may be affected by various sources of error. One of these, spatial variation, is caused by uneven exposure of different parts of an RPPA slide to the reagents used in protein detection. We present a method for the determination and correction of systematic spatial variation in RPPA slides using positive control spots printed on each slide. The method uses a simple bi-linear interpolation technique to obtain a surface representing the spatial variation occurring across the dimensions of a slide. This surface is used to calculate correction factors that can normalize the relative protein concentrations of the samples on each slide. The adoption of the method results in increased agreement between technical and biological replicates of various tumor and cell-line derived samples. Further, in data from a study of the melanoma cell-line SKMEL-133, several slides that had previously been rejected because they had a coefficient of variation (CV greater than 15%, are rescued by reduction of CV below this threshold in each case. The method is implemented in the R statistical programing language. It is compatible with MicroVigene and SuperCurve, packages commonly used in RPPA data analysis. The method is made available, along with suggestions for implementation, at http://bitbucket.org/rppa_preprocess/rppa_preprocess/src.

  19. Digital Phased Array Ultrasonic Inspection system with dynamic focusing

    Science.gov (United States)

    Hwang, J. S.; Shin, H. J.; Song, S. J.; Song, T. K.

    2000-05-01

    Enhancement of the ultrasonic flaw detection and characterization is expected through the development of a high performance PAULI (Phased Array Ultrasonic Inspection) system which can provide high resolution two-dimensional (sector scan: S-scan) images. The high-resolution S-scan image renders inspection results more readable compared to the conventional A-scan and B-scan results. Therefore, it can improve inspection efficiency and reliability. In this study, the ultrasonic imaging technologies developed in medical applications were adapted to develop a digital PAULI system for nondestructive testing. To provide real-time S-scan images, the PAULI system uses 64 independent transceiver channels controlled by proper delay laws for steering and focusing the ultrasound beams along each scan lines. The PAULI system employs a novel dynamic receive focusing technique in order to optimize the lateral resolution by focusing the ultrasound wave at all imaging points. The dynamic receive focusing is achieved in real-time by digital signal processing methods. The feasibility of PAULI system is demonstrated for the NDE of steel structures.

  20. Ultrasonic phased array with surface acoustic wave for imaging cracks

    Science.gov (United States)

    Ohara, Yoshikazu; Oshiumi, Taro; Nakajima, Hiromichi; Yamanaka, Kazushi; Wu, Xiaoyang; Uchimoto, Tetsuya; Takagi, Toshiyuki; Tsuji, Toshihiro; Mihara, Tsuyoshi

    2017-06-01

    To accurately measure crack lengths, we developed a real-time surface imaging method (SAW PA) combining an ultrasonic phased array (PA) with a surface acoustic wave (SAW). SAW PA using a Rayleigh wave with a high sensitivity to surface defects was implemented for contact testing using a wedge with the third critical angle that allows the Rayleigh wave to be generated. Here, to realize high sensitivity imaging, SAW PA was optimized in terms of the wedge and the imaging area. The improved SAW PA was experimentally demonstrated using a fatigue crack specimen made of an aluminum alloy. For further verification in more realistic specimens, SAW PA was applied to stainless-steel specimens with a fatigue crack and stress corrosion cracks (SCCs). The fatigue crack was visualized with a high signal-to-noise ratio (SNR) and its length was measured with a high accuracy of better than 1 mm. The SCCs generated in the heat-affected zones (HAZs) of a weld were successfully visualized with a satisfactory SNR, although responses at coarse grains appeared throughout the imaging area. The SCC lengths were accurately measured. The imaging results also precisely showed complicated distributions of SCCs, which were in excellent agreement with the optically observed distributions.

  1. A phased array antenna for Doppler reflectometry in ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Stefan; Lechte, Carsten; Kasparek, Walter [IGVP, Universitaet Stuttgart, D-70569 Stuttgart (Germany); Hennequin, Pascale [Laboratoire de Physique des Plasmas, CNRS, Ecole Polytech., F-91128 Palaiseau (France); Conway, Garrard; Happel, Tim [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Collaboration: ASDEX Upgrade Team

    2016-07-01

    In a toroidal plasma, Doppler reflectometry (DR) allows investigating electron density fluctuations with finite k {sub perpendicular} {sub to}. The injected microwave beam's frequency determines the radial position of the probed region, its tilt angle selects the wavenumber satisfying the Bragg condition for backscattering. The rotation velocity can be calculated from the Doppler shift of the backscattered signal's frequency. By varying the injected frequency, radial profiles can be reconstructed. Varying the tilt angle resolves the k {sub perpendicular} {sub to} -spectrum of the fluctuations. For DR, a pair of phased array antennas (PAAs) has been designed, built, and installed in the ASDEX Upgrade tokamak. Beam steering is done by slightly changing the injected frequency, thus, the PAAs do not need any movable parts or electronics inside the vacuum vessel. From 75 to 105 GHz, the PAAs feature 13 frequency bands, each with an angular scan range of -20 to +20 {sup circle}. So, for each angle, there are 13 radial positions to be probed. The results from PAA characterisation, commissioning, and first DR measurements are presented.

  2. Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies

    Energy Technology Data Exchange (ETDEWEB)

    Melodelima, David [INSERM, Unite 556, 151 Cours Albert Thomas, 69424 Lyon (France); Lafon, Cyril [INSERM, Unite 556, 151 Cours Albert Thomas, 69424 Lyon (France); Prat, Frederic [Centre Hospitalier Bicetre, 78 Avenue General Leclerc, 94275 Le Kremlin Bicetre (France); Birer, Alain [INSERM, Unite 556, 151 Cours Albert Thomas, 69424 Lyon (France); Cathignol, Dominique [INSERM, Unite 556, 151 Cours Albert Thomas, 69424 Lyon (France)

    2002-12-07

    This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm{sup -2}. By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.

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

    Science.gov (United States)

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

    2012-01-01

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

  4. Observing Pulsars with a Phased Array Feed at the Parkes Telescope

    Science.gov (United States)

    Deng, X.; Chippendale, A. P.; Hobbs, G.; Johnston, S.; Dai, S.; George, D.; Kramer, M.; Karuppusamy, R.; Malenta, M.; Spitler, L.; Tzioumis, T.; Wieching, G.

    2017-07-01

    During 2016 February, CSIRO Astronomy and Space Science and the Max-Planck-Institute for Radio Astronomy installed, commissioned, and carried out science observations with a phased array feed receiver system on the 64-m diameter Parkes radio telescope. Here, we demonstrate that the phased array feed can be used for pulsar observations and we highlight some unique capabilities. We demonstrate that the pulse profiles obtained using the phased array feed can be calibrated and that multiple pulsars can be simultaneously observed. Significantly, we find that an intrinsic polarisation leakage of -31 dB can be achieved with a phased array feed beam offset from the centre of the field of view. We discuss the possibilities for using a phased array feed for future pulsar observations and for searching for fast radio bursts with the Parkes and Effelsberg telescopes.

  5. An Ultra-Wideband Millimeter-Wave Phased Array

    Science.gov (United States)

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

    2016-01-01

    Wideband millimeter-wave arrays are of increasing importance due to their growing use in high data rate systems, including 5G communication networks. In this paper, we present a new class of ultra-wideband millimeter wave arrays that operate from nearly 20 GHz to 90 GHz. The array is based on tightly coupled dipoles. Feeding designs and fabrication challenges are presented, and a method for suppressing feed resonances is provided.

  6. [Determination of five avermectins in bovine liver by on-line solid-phase extraction with hydrophobic monolithic column coupled with high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Li, Xin; Zhang, Yaoqin; Ai, Lianfeng; Wang, Xuesheng; Wang, Manman; Xu, Houjun; Hao, Yulan

    2015-06-01

    A method based on on-line solid-phase extraction (SPE) with hydrophobic monolithic column coupled with high performance liquid chromatography-tandem mass spectrometry was developed for the simultaneous determination of five avermectins in bovine liver. A poly(butyl methacrylate-co-ethylene dimethacrylate) monolithic column was used as the sorbent. The parameters influenced on on-line SPE and separation process such as the loading mobile phase, the eluting flow rate and the solvent for the separation were investigated in detail. Blank samples, spiked samples, matrix effect and recovery experiments were investigated to evaluate the extraction efficiency and potential interfering compounds originating from the matrix. Under the optimized conditions, the method showed a linear range of 1-100 µg/L and the quantification limit of 5 µg/kg for each analyte. The presented method gave recoveries of 77.4%-98.4%. The relative standard deviations of intra-day and inter-day were 4.46%-8.03% and 4.79%-8.68%, respectively. Moreover, no significant changes were found in the extraction performance after more than 400 usages on one monolithic column, and even on the monoliths with various batches. The feasibility of the developed poly (butyl methacrylate-coethylene dimethacrylate) monolithic column based on the on-line SPE method for the determination of avermectins was further demonstrated by the analysis of real samples.

  7. Sensitive Monitoring of Fluoroquinolones in Milk and Honey Using Multiple Monolithic Fiber Solid-Phase Microextraction Coupled to Liquid Chromatography Tandem Mass Spectrometry.

    Science.gov (United States)

    Chen, Lei; Huang, Xiaojia

    2016-11-16

    In the present study, a new multiple monolithic fiber solid-phase microextraction (MMF-SPME) based on poly(apronal-co-divinylbenzene/ethylenedimethacrylate) monolith (APDE) was synthesized. The effect of the preparation parameters of APED on extraction efficiency was studied thoroughly. The combination of APDE/MMF-SPME with high-performance liquid chromatography tandem mass spectrometry detection (HPLC/MS-MS) was developed for sensitive monitoring of ultratrace fluoroquinolones (FQs) in foodstuffs, including milk and honey samples. Under the optimized experimental conditions, the limits of detection (S/N = 3) for the targeted FQs ranged from 0.0019 to 0.018 μg/kg in milk and 0.0010 to 0.0028 μg/kg in honey. The relative standard deviations (RSDs) for method reproducibility were less than 9% in all samples. The established method was successfully applied for the monitoring of FQs residues in milk and honey samples with the recoveries between 74.5% and 116% (RSDs were in the range 0.9-9.5%). In comparison to previous methods, the developed APDE/MMF-SPME-HPLC/MS-MS showed some merits, including satisfactory sensitivity, simplicity, high cost-effectiveness, and low consumption of organic solvent.

  8. Sensitive determination of parabens in human urine and serum using methacrylate monoliths and reversed-phase capillary liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Carrasco-Correa, Enrique Javier; Vela-Soria, Fernando; Ballesteros, Oscar; Ramis-Ramos, Guillermo; Herrero-Martínez, José Manuel

    2015-01-30

    A method for the determination of parabens in human urine and serum by capillary liquid chromatography (cLC) with UV-Vis and mass spectrometry (MS) detection using methacrylate ester-based monolithic columns has been developed. The influence of composition of polymerization mixture was studied. The optimum monolith was obtained with butyl methacrylate monomer at 60/40% (wt/wt) butyl methacrylate/ethylene dimethacrylate ratio and 50wt% porogens (composed of 36wt% of 1,4-butanediol, 54wt% 1-propanol and 10wt% water). Baseline resolution of analytes was achieved through a mobile phase of acetonitrile/water in gradient elution mode. Additionally, dispersive liquid-liquid microextraction (DLLME) was combined with both cLC-UV-Vis and cLC-MS to achieve the determination of parabens in human urine and serum samples with very low limits of detection. Satisfactory intra- and inter-day repeatabilities were obtained in UV-Vis and MS detection, although the latter provided lower detection limits (up to 300-fold) than the UV-Vis detection. Recoveries for the target analytes from spiked biological samples ranged from 95.2% to 106.7%. The proposed methodology for the ultra-low determination of parabens in human urine and serum samples is simple and fast, the consumption of reagents is very low, and very small samples can be analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Graphene oxide reinforced polymeric ionic liquid monolith solid-phase microextraction sorbent for high-performance liquid chromatography analysis of phenolic compounds in aqueous environmental samples.

    Science.gov (United States)

    Sun, Min; Bu, Yanan; Feng, Juanjuan; Luo, Chuannan

    2016-01-01

    A graphene oxide reinforced polymeric ionic liquids monolith was obtained by copolymerization of graphene oxide doped 1-(3-aminopropyl)-3-(4-vinylbenzyl)imidazolium 4-styrenesulfonate monomer and 1,6-di-(3-vinylimidazolium) hexane bihexafluorophosphate cross-linking agent. Coupled to high-performance liquid chromatography, the monolith was used as a solid-phase microextraction sorbent to analyze several phenolic compounds in aqueous samples. Under the optimized extraction and desorption conditions, linear ranges were 5-400 μg/L for 3-nitrophenol, 2-nitrophenol, and 2,5-dichlorophenol and 2-400 μg/L for 4-chlorophenol, 2-methylphenol, and 2,4,6-trichlorophenol (R(2) = 0.9973-0.9988). The limits of detection were 0.5 μg/L for 3-nitrophenol and 2-nitrophenol and 0.2 μg/L for the rest of the analytes. The proposed method was used to determine target analytes in groundwater from an industrial park and river water. None of the analytes was detected. Relative recoveries were in the range of 75.5-113%.

  10. Monolithic poly (SPE-co-BVPE) capillary columns as a novel hydrophilic interaction liquid chromatography stationary phase for the separation of polar analytes.

    Science.gov (United States)

    Foo, Hsiao Ching; Heaton, James; Smith, Norman W; Stanley, Shawn

    2012-10-15

    A novel hydrophilic interaction liquid chromatography (HILIC) stationary phase was prepared by the co-polymerisation of zwitterionic N,N'-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium betaine (SPE) and the crosslinker 1,2-bis(p-vinylphenyl) ethane (BVPE) in the presence of the porogens, toluene and methanol. Monolithic columns were produced by carrying out the α,α'-azoisobutyronitrile (AIBN) initiated reaction for 1, 2, 4, 8 and 12 h inside a 200 μm i.d. fused silica capillary at 75°C (water bath). The optimum polymerisation time was shown to be 2 h, as this resulted in good porosity, due to enlarged flow-channels and the presence of a higher proportion of mesopores provided a relatively larger surface area than the other columns. The chromatographic properties of the optimised poly (SPE-co-BVPE) monolithic column were evaluated with test mixtures containing both basic and neutral compounds in the HILIC gradient separation mode. This produced relatively sharp peaks (average peak width at half height=0.1 min) with average asymmetry factors of 1.4 and baseline resolution was obtained for all the compounds. Using the isocratic separation of the test mixture, the number of theoretical plates (N) per metre calculated was between 26,888 and 35,930 by using average values obtained for triplicate injections of the compounds thiourea, toluene and acrylamide.

  11. Fully Printed, Flexible, Phased Array Antenna for Lunar Surface Communication

    Science.gov (United States)

    Subbaraman, Harish; Hen, Ray T.; Lu, Xuejun; Chen, Maggie Yihong

    2013-01-01

    NASAs future exploration missions focus on the manned exploration of the Moon, Mars, and beyond, which will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit, and back to Earth. Flexible antennas are highly desired in many scenarios. Active phased array antennas (active PAAs) with distributed control and processing electronics at the surface of an antenna aperture offer numerous advantages for radar communications. Large-area active PAAs on flexible substrates are of particular interest in NASA s space radars due to their efficient inflatable package that can be rolled up during transportation and deployed in space. Such an inflatable package significantly reduces stowage volume and mass. Because of these performance and packaging advantages, large-area inflatable active PAAs are highly desired in NASA s surface-to-orbit and surface-to-relay communications. To address the issues of flexible electronics, a room-temperature printing process of active phased-array antennas on a flexible Kapton substrate was developed. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proved feasible for the PAA system. This innovation is a new type of fully inkjet-printable, two-dimensional, high-frequency PAA on a flexible substrate at room temperature. The designed electronic circuit components, such as the FET switches in the phase shifter, metal interconnection lines, microstrip transmission lines, etc., are all printed using a special inkjet printer. Using the developed technology, entire 1x4, 2x2, and 4x4 PAA systems were developed, packaged, and demonstrated at 5.3 GHz. Several key solutions are addressed in this work to solve the fabrication issues. The source/drain contact is developed using droplets of silver ink printed on the source/drain areas prior to applying CNT thin-film. The wet silver ink droplets allow the silver to

  12. The measurement of echodirection in a phased-array radar

    NARCIS (Netherlands)

    Rijsdijk, F.B.; Spek, G.A. van der

    1978-01-01

    For a planar-array antenna with a monopulse feed horn, this study describes a simple algorithm for the determination of the direction of target echoes. Antenna pattern measurements of the array indicate that the direction sines of a received wavefront can be independently obtained with one simple

  13. Analysis of finite phased arrays of circular microstrip patches

    Science.gov (United States)

    Deshpande, Manohar D.; Bailey, Marion C.

    1989-01-01

    A method is presented for analyzing a finite planar array of circular microstrip patches fed by coaxial probes. The self- and mutual impedances between array elements are calculated using the method of moments with the dyadic Green's function for a dielectric layer on a ground plane. The patch circuits are determined by using the reaction integral equation. The active input impedance as well as the active element pattern of the array are computed from a knowledge of the resultant patch currents. The calculated results for two-element and eight-element linear arrays are in good agreement with experimental data. The active reflection coefficient and element pattern for the center and edge elements of a two-dimensional array as a function of scan angle are also presented.

  14. Detection of wheel rim by immersion scan of phased array ultrasonic flaw testing

    Science.gov (United States)

    Cai, Yi-He; Guo, Jian-qiang; Wang, Ze-yong; Gao, Xiao-rong; Jiang, Xiang-dong; Li, Xi

    2015-02-01

    In order to achieve the in-service detection to high speed train wheel rims, this article analyzed the effects of the number of array elements to image focusing and image quality using water immersion ultrasonic phased array technology. Also, the effects of the depth of water to detecting technique had been researched. According to the results of the experiments, the number of optimal array elements, the corresponding thickness of immersion layer, and the optimal range of water's depth had been obtained. Thus, appropriate references had been provided to water immersion ultrasonic phased array testing.

  15. Joint Gain/Phase and Mutual Coupling Array Calibration Technique with Single Calibrating Source

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2012-01-01

    Full Text Available An iterative-based method for joint gain/phase and mutual coupling array calibration is proposed in this paper. It estimates the array gain/phase and mutual coupling coefficients with a set of simultaneous equations formed by using the beam pattern property of the array. Only one calibrating source with known direction is requiblue to obtain the unique estimate. The effectiveness of this approach is illustrated by simulation results and by experimental data collected with an antenna array operating in high-frequency radio band.

  16. A New Calibration Method for Microphone Array with Gain, Phase, and Position Errors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microphone array can be used in sound source localization and separation. But gain, phase, and position errors can seriously influence the performance of localization algorithms such as multiple signal classification (MUSIC) algorithm. In this paper, a new calibration method for microphone array with gain, phase, and position errors is proposed. Unlike traditional calibration methods for antenna array, the proposed method can be used in the broadband and near-field signal model such as microphone array with arbitrary sensor geometries in one plane. Computer simulations are presented and simulation results show the new method having good performance.

  17. Porous polymer monolithic col

    Directory of Open Access Journals (Sweden)

    Lydia Terborg

    2015-05-01

    Full Text Available A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation of surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46–4.51 molecules/nm2 significantly exceeded that of mercaptoalkanoic acids with 2.39–2.45 molecules/nm2. The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water and ion exchange chromatographic modes (applying gradient of salt in water, respectively.

  18. Metal Organic Vapor Phase Epitaxy of Monolithic Two-Color Light-Emitting Diodes Using an InGaN-Based Light Converter

    Science.gov (United States)

    Damilano, Benjamin; Kim-Chauveau, Hyonju; Frayssinet, Eric; Brault, Julien; Hussain, Sakhawat; Lekhal, Kaddour; Vennéguès, Philippe; De Mierry, Philippe; Massies, Jean

    2013-09-01

    Monolithic InGaN-based light-emitting diodes (LEDs) using a light converter fully grown by metal organic vapor phase epitaxy are demonstrated. The light converter, consisting of 10-40 InGaN/GaN quantum wells, is grown first, followed by a violet pump LED. The structure and growth conditions of the pump LED are specifically adapted to avoid thermal degradation of the light converter. Electroluminescence analysis shows that part of the pump light is absorbed by the light converter and reemitted at longer wavelength. Depending on the emission wavelength of the light converter, different LED colors are achieved. In particular, for red-emitting light converters, a color temperature of 2100 K corresponding to a tint between warm white and candle light is demonstrated.

  19. High-Sensitivity Phased Arrays for Radio Astronomy and Satellite Communications

    Science.gov (United States)

    Diao, Junming

    Radio astronomy is used to study stars, galaxies, black holes and gas clouds radiation at radio frequencies. Detecting extremely weak signals from deep space radio sources requires high sensitive feed system associated with large dish antennas. The key figure of merit is survey speed, or the time required to map a region of the sky to a given source flux density. Survey speed is proportional to the frequency bandwidth, the field of view or observable region of the sky, and the squared sensitivity, where sensitivity is related to reflector aperture efficiency and system noise temperature. Compared to the traditional single feed, phased array feeds with significantly expanded field of view are considered as the next generation feed for radio telescope. This dissertation outlines the design, analysis and measurement of high sensitivity L-band and mm-wave phased array feeds for the 100-meter Green Bank Telescope. Theoretical works for radio astronomy includes design guideline for high sensitivity phased array feed, fundamental frequency bandwidth limit, array antenna loss influenced by mutual coupling and beamformer coefficients and possibility of superdirectivity for radio telescopes and other antennas. These study are helpful to understand and guide the design of a phased array feed system. In the absence of dish antennas, sparse phased arrays with aperiodic structure have been developed for satellite communications. A compromise between the peak side lobe level, array element density, directivity and design complexity is studied. We have found that the array peak side lobe level can be reduced by enhancing the array element direction at the main lobe direction, increasing the array element density and enlarging the array size. A Poynting streamline approach develops to understand the properties of a receiving antenna and the mutual coupling effects between array elements. This method has been successfully used to generate effective area shape for many types of

  20. Separation of intact proteins on γ-ray-induced polymethacrylate monolithic columns: A highly permeable stationary phase with high peak capacity for capillary high-performance liquid chromatography with high-resolution mass spectrometry.

    Science.gov (United States)

    Simone, Patrizia; Pierri, Giuseppe; Foglia, Patrizia; Gasparrini, Francesca; Mazzoccanti, Giulia; Capriotti, Anna Laura; Ursini, Ornella; Ciogli, Alessia; Laganà, Aldo

    2016-01-01

    Polymethacrylate-based monolithic capillary columns, prepared by γ-radiation-induced polymerization, were used to optimize the experimental conditions (nature of the organic modifiers, the content of trifluoroacetic acid and the column temperature) in the separation of nine standard proteins with different hydrophobicities and a wide range of molecular weights. Because of the excellent permeability of the monolithic columns, an ion-pair reversed-phase capillary liquid chromatography with high-resolution mass spectrometry method has been developed by coupling the column directly to the mass spectrometer without a flow-split and using a standard electrospray interface. Additionally, the high working flow and concomitant high efficiency of these columns allowed us to employ a longer column (up to 50 cm) and achieve a peak capacity value superior to 1000. This work is motivated by the need to develop new materials for high-resolution chromatographic separation that combine chemical stability at elevated temperatures (up to 75°C) and a broad pH range, with a high peak capacity value. The advantage of the γ-ray-induced monolithic column lies in the batch-to-batch reproducibility and long-term high-temperature stability. Their proven high loading capacity, recovery, good selectivity and high permeability, moreover, compared well with that of a commercially available poly(styrene-divinylbenzene) monolithic column, which confirms that such monolithic supports might facilitate analysis in proteomics.

  1. Target tracking and pointing for arrays of phase-locked lasers

    Science.gov (United States)

    Macasaet, Van P.; Hughes, Gary B.; Lubin, Philip; Madajian, Jonathan; Zhang, Qicheng; Griswold, Janelle; Kulkarni, Neeraj; Cohen, Alexander; Brashears, Travis

    2016-09-01

    Arrays of phase-locked lasers are envisioned for planetary defense and exploration systems. High-energy beams focused on a threatening asteroid evaporate surface material, creating a reactionary thrust that alters the asteroid's orbit. The same system could be used to probe an asteroid's composition, to search for unknown asteroids, and to propel interplanetary and interstellar spacecraft. Phased-array designs are capable of producing high beam intensity, and allow beam steering and beam profile manipulation. Modular designs allow ongoing addition of emitter elements to a growing array. This paper discusses pointing control for extensible laser arrays. Rough pointing is determined by spacecraft attitude control. Lateral movement of the laser emitter tips behind the optical elements provides intermediate pointing adjustment for individual array elements and beam steering. Precision beam steering and beam formation is accomplished by coordinated phase modulation across the array. Added cells are incorporated into the phase control scheme by precise alignment to local mechanical datums using fast, optical relative position sensors. Infrared target sensors are also positioned within the datum scheme, and provide information about the target vector relative to datum coordinates at each emitter. Multiple target sensors allow refined determination of the target normal plane, providing information to the phase controller for each emitter. As emitters and sensors are added, local position data allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. Mechanical design and associated phase control that is scalable for target distance and number of emitters is presented.

  2. In-plane shear piezoelectric wafer active sensor phased arrays for structural health monitoring

    Science.gov (United States)

    Wang, Wentao; Zhou, Wensong; Wang, Peng; Wang, Chonghe; Li, Hui

    2016-04-01

    This paper proposes a new way for guided wave structural health monitoring using in-plane shear (d36 type) piezoelectric wafer active sensors phased arrays. Conventional piezoelectric wafer active sensors phased arrays based on inducing into specific Lamb wave modes (d31 type) has already widely used for health monitoring of the thin-wall structures. Rather than Lamb wave modes, the in-plane shear piezoelectric wafer active sensors phased arrays induces in-plane shear horizontal (SH) guided waves. The SH guided waves are distinct with the Lamb waves with simple waveform and less additional converted wave modes and the zero symmetric mode (SH0) is non-dispersive. In this paper, the advantage of the shear horizontal wave and the in-plane shear piezoelectric wafers capability to generate SH waves is first reviewed. Then finite element analysis of a 4-in-plane shear wafer active sensors phased array embedded on a rectangular aluminium plate is performed. In addition, numerical simulations with respect to creaks with different sizes as well as locations are implemented by the in-plane shear wafer active sensors phased array. For comparison purposes, the same numerical simulations using the conventional piezoelectric wafer active sensors phased arrays are also employed at the same time. Results indicate that the in-plane shear (d36 type) piezoelectric wafer active sensors phased arrays has the potential to identify damage location and assess damage severity in structural health monitoring.

  3. Monolithic microchannel heatsink

    Science.gov (United States)

    Benett, William J.; Beach, Raymond J.; Ciarlo, Dino R.

    1996-01-01

    A silicon wafer has slots sawn in it that allow diode laser bars to be mounted in contact with the silicon. Microchannels are etched into the back of the wafer to provide cooling of the diode bars. To facilitate getting the channels close to the diode bars, the channels are rotated from an angle perpendicular to the diode bars which allows increased penetration between the mounted diode bars. This invention enables the fabrication of monolithic silicon microchannel heatsinks for laser diodes. The heatsinks have low thermal resistance because of the close proximity of the microchannels to the laser diode being cooled. This allows high average power operation of two-dimensional laser diode arrays that have a high density of laser diode bars and therefore high optical power density.

  4. Effect of Distributor Design on Gas-Liquid Distribution in Monolithic Bed at High Gas/Liquid Ratios

    Institute of Scientific and Technical Information of China (English)

    周媛; AL-DAHHAN Muthanna; DUDUKOVIC Milorad; 刘辉

    2012-01-01

    Experiments were carried out to investigate the liquid flow distribution at high gas/liquid ratios in a cold model monolith bed of a 0.048 m diameter with 62 cells per cm2.Three types of distributor for the liquid distribu-tion were used to evaluate their distribution performance.Local liquid saturation in individual channels was meas-ured using 16 single-point optical fiber probes mounted inside the channels.The results indicate that 1) The optical fiber probe technique can measure phase distribution in the monolith bed;2) Liquid saturation distribution along the radial direction of the monolith bed is not uniform and the extent of non-uniformity depends on the distributor de-sign and phase velocities;and 3) The tube array distributor provides superior liquid distribution performance over the showerhead and nozzle distributors.

  5. From Vision to Reality: 50 Years of Phased Array Development

    Science.gov (United States)

    2016-09-30

    heavily involved in its design and testing. It contained four S-band array faces , each with 5,000 elements (the array is the smaller circular...building being used in television science fiction programs representing various kinds of alien structures). The Perimeter Acquisition Radar (PAR), shown...site. (USGov-Military-Air Force) Figure 5. Perimeter Acquisition Radar (PAR) The PAR’s role in missile defense was long-range surveillance and

  6. Near-Field Ultrasonic Phased Array Deflection Focusing Based CFRP Wing Box Structural Health Monitoring

    OpenAIRE

    Yajie Sun; Yonghong Zhang; Chengshan Qian; Zijia Zhang

    2013-01-01

    Near-field ultrasonic phased array theory is researched and utilized in the carbon-fiber wing box to identify the damage in the structure. Near-field ultrasonic phased array based structural health monitoring is researched to overcome the limitation of the far-field ultrasonic phased array in monitoring scope. The time delay of the theory and the process of the damage identification method are researched in detail. The recognition result is shown in a mapped image. The proposed method is appl...

  7. Diffractive-optics-based beam combination of a phase-locked fiber laser array.

    Science.gov (United States)

    Cheung, Eric C; Ho, James G; Goodno, Gregory D; Rice, Robert R; Rothenberg, Josh; Thielen, Peter; Weber, Mark; Wickham, Michael

    2008-02-15

    A diffractive optical element (DOE) is used as a beam combiner for an actively phase-locked array of fiber lasers. Use of a DOE eliminates the far-field sidelobes and the accompanying loss of beam quality typically observed in tiled coherent laser arrays. Using this technique, we demonstrated coherent combination of five fiber lasers with 91% efficiency and M2=1.04. Combination efficiency and phase locking is robust even with large amplitude and phase fluctuations on the input laser array elements. Calculations and power handling measurements suggest that this approach can scale to both high channel counts and high powers.

  8. Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS)

    Science.gov (United States)

    Johnston, Pat H.

    2010-01-01

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading. Keywords: Phased Array, Ultrasonics, Composites, Out-of-Autoclave

  9. Near-Field Ultrasonic Phased Array Deflection Focusing Based CFRP Wing Box Structural Health Monitoring

    OpenAIRE

    Yajie Sun; Yonghong Zhang; Chengshan Qian; Zijia Zhang

    2013-01-01

    Near-field ultrasonic phased array theory is researched and utilized in the carbon-fiber wing box to identify the damage in the structure. Near-field ultrasonic phased array based structural health monitoring is researched to overcome the limitation of the far-field ultrasonic phased array in monitoring scope. The time delay of the theory and the process of the damage identification method are researched in detail. The recognition result is shown in a mapped image. The proposed method is appl...

  10. Meteorological Sensor Array (MSA)-Phase I. Volume 2 (Data Management Tool: Proof of Concept)

    Science.gov (United States)

    2014-10-01

    Meteorological Sensor Array ( MSA )–Phase I, Volume 2 (Data Management Tool: “Proof of Concept”) by Sandra Harrison and Gail Vaucher ARL...Missile Range, NM 88002-5501 ARL-TR-7133 October 2014 Meteorological Sensor Array ( MSA )–Phase I, Volume 2 (Data Management Tool: “Proof...2014–September 30, 2014 4. TITLE AND SUBTITLE Meteorological Sensor Array ( MSA )–Phase I, Volume 2 (Data Management Tool: “Proof of Concept”) 5a

  11. Optical phase-locked loop signal sources for phased-array communications antennas

    Science.gov (United States)

    Langley, Lloyd N.; Edge, Colin; Wale, Michael J.; Gliese, Ulrik B.; Seeds, Alwyn J.; Walton, Channing; Wright, James G.; Coryell, Louis A.

    1997-10-01

    A coherent, optical heterodyne approach to signal generation and beamforming is particularly advantageous in multi-beam mobile phased arrays. Use of optical technology allows an optimum distribution of weight and power to be achieved between the antenna face and central electronics, together with an efficient implementation of the beamforming function and a modular design approach in which the basic building blocks are frequency-independent. Systems of this type employ a pair of optical carriers with a difference frequency equal to the required microwave signal. Phased- locking is necessary in order to achieve sufficiently low phase noise in the radio communication link. Optical phase locked loops (OPLLs) have been shown to be potential candidates for this application, yet work still needs to be done to bring them from the laboratory to field demonstrations. This paper describes the construction of a laser-diode OPLL subsystem for evaluation in a proof-of- concept beamforming system. This involves optimization of the loop design, development of single-frequency laser diodes with the correct linewidth, modulation and tuning characteristics and integration into a micro-optic assembly with custom wideband electronics.

  12. Control of the necrosed tissue volume during noninvasive ultrasound surgery using a 16-element phased array.

    Science.gov (United States)

    Fan, X; Hynynen, K

    1995-03-01

    Focused high-power ultrasound beams are well suited for noninvasive local destruction of deep target volumes. In order to avoid cavitation and to utilize only thermal tissue damage, high frequencies (1-5 MHz) are used in ultrasonic surgery. However, the focal spots generated by sharply focused transducers become so small that only small tumors can be treated in a reasonable time. Phased array ultrasound transducers can be employed to electronically scan a focal spot or to produce multiple foci in the desired region to increase the treated volume. In this article, theoretical and experimental studies of spherically curved square-element phased arrays for use in ultrasonic surgery were performed. The simulation results were compared with experimental results from a 16-element array. It was shown that the phased array could control the necrosed tissue volume by using closely spaced multiple foci. The phased array can also be used to enlarge a necrosed tissue volume in only one direction at a time, i.e., lateral or longitudinal. The spherically curved 16 square-element phased array can produce useful results by varying the phase and amplitude setting. Four focal points can be easily generated with a distance of two or four wavelengths between the two closest peaks. The maximum necrosed tissue volume generated by the array can be up to sixteen times the volume induced by a similar spherical transducer. Therefore the treatment time could be reduced compared with single transducer treatment.

  13. A 24-GHz portable FMCW radar with continuous beam steering phased array (Conference Presentation)

    Science.gov (United States)

    Peng, Zhengyu; Li, Changzhi

    2017-05-01

    A portable 24-GHz frequency-modulated continuous-wave (FMCW) radar with continuous beam steering phased array is presented. This board-level integrated radar system consists of a phased array antenna, a radar transceiver and a baseband. The phased array used by the receiver is a 4-element linear array. The beam of the phased array can be continuously steered with a range of ±30° on the H-plane through an array of vector controllers. The vector controller is based on the concept of vector sum with binary-phase-shift attenuators. Each vector controller is capable of independently controlling the phase and the amplitude of each element of the linear array. The radar transceiver is based on the six-port technique. A free-running voltage controlled oscillator (VCO) is controlled by an analog "sawtooth" voltage generator to produce frequency-modulated chirp signal. This chirp signal is used as the transmitter signal, as well as the local oscillator (LO) signal to drive the six-port circuit. The transmitter antenna is a single patch antenna. In the baseband, the beat signal of the FMCW radar is detected by the six-port circuit and then processed by a laptop in real time. Experiments have been performed to reveal the capabilities of the proposed radar system for applications including indoor inverse synthetic aperture radar (ISAR) imaging, vital sign detection, and short-range navigation, etc. (This abstract is for the profiles session.)

  14. Characterization of the system functions of ultrasonic linear phased array inspection systems.

    Science.gov (United States)

    Huang, Ruiju; Schmerr, Lester W

    2009-02-01

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

  15. Phase-locked array of quantum cascade lasers with an intracavity spatial filter

    Science.gov (United States)

    Jia, Zhiwei; Wang, Lei; Zhang, Jinchuan; Zhao, Yue; Liu, Chuanwei; Zhai, Shenqiang; Zhuo, Ning; Liu, JunQi; Wang, LiJun; Liu, ShuMan; Liu, Fengqi; Wang, Zhanguo

    2017-08-01

    We show a phase-locked array of quantum cascade lasers with an intracavity spatial filter based on the Talbot effect. All the laser arrays show in-phase operation from the threshold current to full power current with a near-diffraction-limited divergence angle. The maximum power is just about 5 times that of a single-ridge laser for an eleven-laser array device and 3 times for a seven-laser array device. The structure was analyzed by using the multi-slit Fraunhofer diffraction theory, showing very good agreement with the experimental results. Considering the great modal selection ability, simple fabricating process, and potential for achieving continuous wave operation, this phase-locked array may be a hopeful solution to obtain higher coherent power.

  16. Monoliths in Bioprocess Technology

    Directory of Open Access Journals (Sweden)

    Vignesh Rajamanickam

    2015-04-01

    Full Text Available Monolithic columns are a special type of chromatography column, which can be used for the purification of different biomolecules. They have become popular due to their high mass transfer properties and short purification times. Several articles have already discussed monolith manufacturing, as well as monolith characteristics. In contrast, this review focuses on the applied aspect of monoliths and discusses the most relevant biomolecules that can be successfully purified by them. We describe success stories for viruses, nucleic acids and proteins and compare them to conventional purification methods. Furthermore, the advantages of monolithic columns over particle-based resins, as well as the limitations of monoliths are discussed. With a compilation of commercially available monolithic columns, this review aims at serving as a ‘yellow pages’ for bioprocess engineers who face the challenge of purifying a certain biomolecule using monoliths.

  17. Widely tunable narrow-linewidth 1.5 μm light source based on a monolithically integrated quantum dot laser array

    Science.gov (United States)

    Becker, A.; Sichkovskyi, V.; Bjelica, M.; Rippien, A.; Schnabel, F.; Kaiser, M.; Eyal, O.; Witzigmann, B.; Eisenstein, G.; Reithmaier, J. P.

    2017-05-01

    A monolithically integrated widely tunable narrow-linewidth light source was realized on an InP-based quantum dot (QD) gain material. The quasi zero-dimensional nature of QDs and the resulting low linewidth enhancement factor enabled standalone distributed feedback (DFB) lasers with intrinsic linewidths as low as 110 kHz. An integrated device comprising four DFB lasers with on-chip micro-heaters, a 3 dB-coupler network, and a semiconductor optical amplifier (SOA), which covers the entire C+ telecom band, exhibits a linewidth of below 200 kHz independent of the SOA operation current.

  18. Highly integrated application specific MMICs for active phased array radar applications

    NARCIS (Netherlands)

    Bogaart, F.L.M. van den

    1999-01-01

    Application specific MMIC solutions for active array radar, developed at TNO-FEL, are presented. The use and application of these MMICs in their respective radar systems will be shown. These MMICs address the needs for current and future phased-array topologies as for example the concept of "smart

  19. Highly Integrated Application Specific MMICS for Active Phased Array Radar Applications

    NARCIS (Netherlands)

    Bogaart, F.L.M. van den

    2000-01-01

    Application specific MMIC solutions for active array radar, developed at TNO-FEL. are presented. The use and application of these MMICs in their respective radar systems will be shown. These MMICs address the needs for current and future phased-array topologies as for example the concept of "smart

  20. Array calibration of angularly dependent gain and phase uncertainties with carry-on instrumental sensors

    Institute of Scientific and Technical Information of China (English)

    WANG Buhong; WANG Yongliang; CHEN Hui; GUO Ying

    2004-01-01

    Array calibration with angularly dependent gain and phase uncertainties has long been a difficult problem. Although many array calibration methods have been reported extensively in the literature, they almost all assumed an angularly independent model for array uncertainties. Few calibration methods have been developed for the angularly dependent array uncertainties. A novel and efficient auto-calibration method for angularly dependent gain and phase uncertainties is proposed in this paper, which is called ISM (Instrumental Sensors Method). With the help of a few well-calibrated instrumental sensors, the ISM is able to achieve favorable and unambiguous direction-of-arrivals (DOAs) estimate and the corresponding angularly dependent gain and phase estimate simultaneously, even in the case of multiple non-disjoint sources. Since the mutual coupling and sensor position errors can all be described as angularly dependent gain/phase uncertainties, the ISM proposed still works in the presence of a combination of all these array perturbations. The ISM can be applied to arbitrary array geometries including linear arrays. The ISM is computationally efficient and requires only one-dimensional search, with no high-dimensional nonlinear search and convergence burden involved. Besides, no small error assumption is made, which is always an essential prerequisite for many existing array calibration techniques. The estimation performance of the ISM is analyzed theoretically and simulation results are provided to demonstrate the effectiveness and behavior of the proposed ISM.

  1. A spherical wave expansion model of sequentially rotated phased arrays with arbitrary elements

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2007-01-01

    An analytical model of sequentially rotated phased arrays with arbitrary antenna elements is presented. It is applied to different arrays and the improvements of axial ratio bandwidth and copolar directivity are investigated. It is compared to a numerical method of auxiliary Sources model to asce...

  2. Highly Integrated Application Specific MMICS for Active Phased Array Radar Applications

    NARCIS (Netherlands)

    Bogaart, F.L.M. van den

    2000-01-01

    Application specific MMIC solutions for active array radar, developed at TNO-FEL. are presented. The use and application of these MMICs in their respective radar systems will be shown. These MMICs address the needs for current and future phased-array topologies as for example the concept of "smart s

  3. Highly integrated application specific MMICs for active phased array radar applications

    NARCIS (Netherlands)

    Bogaart, F.L.M. van den

    1999-01-01

    Application specific MMIC solutions for active array radar, developed at TNO-FEL, are presented. The use and application of these MMICs in their respective radar systems will be shown. These MMICs address the needs for current and future phased-array topologies as for example the concept of "smart s

  4. A Broadband Conformal Phased Array Antenna on Spherical Surface

    Directory of Open Access Journals (Sweden)

    Dan Sun

    2014-01-01

    Full Text Available A Ku-band wideband conformal array antenna with 13×19 elements is presented in the paper. The array has a spherical structure, and its element is a proximity-coupled stacked patches antenna with a cavity-backed ground plane. The stacked patches and the cavity produce multiple coupled resonances, which enhance the bandwidth of the element extremely. A simulated model with the reasonable dimensions is framed with the coupling analyses, and the effective simulated results and good computing efficiency are obtained simultaneously. The measured results of the center embedded element in the whole array show a bandwidth exceeding 40% VSWR<2, which is close to the simulated matching performance.

  5. Beam pattern improvement by compensating array nonuniformities in a guided wave phased array

    Science.gov (United States)

    Kwon, Hyu-Sang; Lee, Seung-Seok; Kim, Jin-Yeon

    2013-08-01

    This paper presents a simple data processing algorithm which can improve the performance of a uniform circular array based on guided wave transducers. The algorithm, being intended to be used with the delay-and-sum beamformer, effectively eliminates the effects of nonuniformities that can significantly degrade the beam pattern. Nonuniformities can arise intrinsically from the array geometry when the circular array is transformed to a linear array for beam steering and extrinsically from unequal conditions of transducers such as element-to-element variations of sensitivity and directivity. The effects of nonuniformities are compensated by appropriately imposing weight factors on the elements in the projected linear array. Different cases are simulated, where the improvements of the beam pattern, especially the level of the highest sidelobe, are clearly seen, and related issues are discussed. An experiment is performed which uses A0 mode Lamb waves in a steel plate, to demonstrate the usefulness of the proposed method. The discrepancy between theoretical and experimental beam patterns is explained by accounting for near-field effects.

  6. Radiation detection from phase-locked serial dc SQUID arrays

    DEFF Research Database (Denmark)

    Kaplunenko, V. K.; Mygind, Jesper; Pedersen, Niels Falsig

    1993-01-01

    on the external loading. For small loading it was N times smaller than expected for a single cell. The influence of the inductive coupling mechanism on the operation of discrete Josephson junction circuits and the similarity to the coupling in layered structures of long Josephson junctions is discussed. Journal......We report on synchronous operation of series arrays of inductively coupled superconducting quantum interference devices (SQUIDs). Each array consisted of N=3 or 11 dc SQUIDs with common inductances providing a strong interaction between neighboring cells. Externally shunted (betac...

  7. A parametric study of ultrasonic beam profiles for a linear phased array transducer.

    Science.gov (United States)

    Lee, J H; Choi, S W

    2000-01-01

    A numerical simulation model is presented to investigate the influences of design parameters of linear phased array transducers on beam focusing and steering performance. The characteristic of ultrasonic beam profiles has been simulated on the basis of the Huygen's superposition principle. For the simulation, a linear phased array is considered as the composition of finite number of elements separated by equidistance. Individual elements are considered as two-dimensional point sources. The waves generated from piezoelectric elements are considered as simplified transient ultrasonic waves that are constructed with the cosine function enveloped with a Hanning window. The characteristic of ultrasonic wave propagation into a medium from the phased array transducer is described. The effects of the number, the interelement spacing, steering angle, the focal length, and frequency bandwidth of the piezoelectric elements on beam directivity and ultrasonic pressure field in a linear phased array transducer are systematically discussed.

  8. Phased Array Ultrasonic Sound Field Mapping in Cast Austenitic Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Susan L.; Prowant, Matthew S.; Cinson, Anthony D.; Larche, Michael R.; Diaz, Aaron A.; Anderson, Michael T.

    2014-05-31

    This study maps the phased array-generated acoustic sound fields through three types of CASS microstructure in four specimens to quantitatively assess the beam formation effectiveness in these materials.

  9. A Multi-Band Photonic Phased Array Antenna for High-Data Rate Communication Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Multi-band phased array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. In order to steer...

  10. SPS-ALPHA: The First Practical Solar Power Satellite via Arbitrarily Large PHased Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SPS-ALPHA (Solar Power Satellite via Arbitrarily Large Phased Array) is a novel, bio-mimetic approach to the challenge of space solar power. If successful, this...

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

    Science.gov (United States)

    Dao, Gavin; Ginzel, Robert

    2014-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dao, Gavin [Advanced OEM Solutions, 8044 Montgomery Road 700, Cincinnati OH 45236 (United States); Ginzel, Robert [Eclipse Scientific, 97 Randall, Waterloo, Ontario N2V 1C5 (Canada)

    2014-02-18

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

  13. Array illumination with minimal non-uniformity based on generalized phase contrast

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2009-01-01

    The generalized phase contrast method (GPC) has been previously shown to be an efficient technique for generating array illumination and is thus highly suitable for such applications as dynamic multiple beam trapping and optical micromanipulation. However, projected arrays usually exhibit intensity...... roll-offs that may be undesirable for some applications. We show that the uniformity of GPC-generated array illuminations can be improved using intuitive corrections to the input spatial phase modulation, by increasing or decreasing it to respectively raise or lower the intensity of the corresponding...... output spots to improve uniformity. This is combined with matching corrections to the phase shift introduced by the phase contrast filter. Results from numerical experiments show that the array illumination uniformity error improves from over 40% to less than 1% while maintaining the efficiency prior...

  14. A Multi-band Photonic Phased Array Antenna for High-Date Rate Communication Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Multi-band phased array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. In order to steer...

  15. Excitation of ultrasonic Lamb waves using a phased array system with two array probes: phantom and in vitro bone studies.

    Science.gov (United States)

    Nguyen, Kim-Cuong T; Le, Lawrence H; Tran, Tho N H T; Sacchi, Mauricio D; Lou, Edmond H M

    2014-07-01

    Long bones are good waveguides to support the propagation of ultrasonic guided waves. The low-order guided waves have been consistently observed in quantitative ultrasound bone studies. Selective excitation of these low-order guided modes requires oblique incidence of the ultrasound beam using a transducer-wedge system. It is generally assumed that an angle of incidence, θi, generates a specific phase velocity of interest, co, via Snell's law, θi=sin(-1)(vw/co) where vw is the velocity of the coupling medium. In this study, we investigated the excitation of guided waves within a 6.3-mm thick brass plate and a 6.5-mm thick bovine bone plate using an ultrasound phased array system with two 0.75-mm-pitch array probes. Arranging five elements as a group, the first group of a 16-element probe was used as a transmitter and a 64-element probe was a receiver array. The beam was steered for six angles (0°, 20°, 30°, 40°, 50°, and 60°) with a 1.6-MHz source signal. An adjoint Radon transform algorithm mapped the time-offset matrix into the frequency-phase velocity dispersion panels. The imaged Lamb plate modes were identified by the theoretical dispersion curves. The results show that the 0° excitation generated many modes with no modal discrimination and the oblique beam excited a spectrum of phase velocities spread asymmetrically about co. The width of the excitation region decreased as the steering angle increased, rendering modal selectivity at large angles. The phenomena were well predicted by the excitation function of the source influence theory. The low-order modes were better imaged at steering angle ⩾30° for both plates. The study has also demonstrated the feasibility of using the two-probe phased array system for future in vivo study.

  16. Validated method for bioactive lignans in Schisandra chinensis in vitro cultures using a solid phase extraction and a monolithic column application.

    Science.gov (United States)

    Brezinová, Lenka; Vlasínová, Helena; Havel, Ladislav; Humpa, Otakar; Slanina, Jirí

    2010-09-01

    A simple and rapid method for determination of six lignans found in plant cell cultures of Schisandra chinensis was developed and validated. The lignans were extracted from plant samples with methanol and the extracts were effectively cleaned by solid-phase extraction using Strata C18-E (Phenomenex) cartridges. Chromatographic separation was carried out on a Chromolith Performance RP-18e monolithic column (100 x 4.6 mm, Merck) using an isocratic mobile phase of acetonitrile and water in a 50:50 (v/v) ratio. The eluent was monitored at 220 nm. The baseline separation of schizandrin, gomisin A, deoxyschizandrin, gamma-schizandrin, gomisin N and wuweizisu C was achieved in a relatively short time period (20 min), which was made possible by the relatively high flow rate of the mobile phase (2 mL/min). The lower limit of quantitation was 0.1 mg/L for schizandrin and gomisin A, 0.3 mg/L for deoxyschizandrin, gamma-schizandrin, and gomisin N and 1 mg/L for wuweizisu C. The analysis of spiked samples containing six lignans provided absolute recoveries between 93 and 101% in all cases. The validated method was successfully applied to the determination of lignans in embryogenic plant cell cultures of Schisandra chinensis.

  17. Phased Array Ultrasonic Examination of Space Shuttle Main Engine Nozzle Weld

    Science.gov (United States)

    James, S.; Engel, J.; Kimbrough, D.; Suits, M.; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes a Phased Array Ultrasonic Examination that was developed for the examination of a limited access circumferential Inconel 718 fusion weld of a Space Shuttle Main Engine Nozzle - Cone. The paper discusses the selection and formation criteria used for the phased array focal laws, the reference standard that simulated hardware conditions, the examination concept, and results. Several unique constraints present during this examination included limited probe movement to a single axis and one-sided access to the weld.

  18. True Time Delay Scheme for X-band Phased Array Radar

    Institute of Scientific and Technical Information of China (English)

    LI Zheng

    2007-01-01

    The system of a true-time delay line for X-band and 8-unit phased array antennas is introduced. Changing the length of a chirp grating with piezotranslator(PZT), the variable delay is obtained. The scheme is applied to X-band phased array radar whose searching data rate is 56/s. It is simulated that the beam squinting is influenced by the error of real time delay. The relation between the beamforming mode and its modifying volt is discussed.

  19. PHASE-LOCKED 2-D JOSEPHSON JUNCTION ARRAYS AS SUBMILLIMETER OSCILLATORS

    Institute of Scientific and Technical Information of China (English)

    Gao Bin; Guan Boran

    2002-01-01

    This letter presents the results of numerical simulations for phase-locked 2-D Josephson junction array oscillator. The simulation result shows that the junctions of 2-D array can mutually phase-locked in a considerable area if the parameters can be carefully selected. The oscillators are formed with up to 33 identical Nb/AlOx/Nb junctions, and the junctions are connected with Nb microstrip resonators. Optimum structure parameters for oscillator circuit design can be obtained with these simulation results.

  20. Vapor Phase Detection Using Chemi-Resistor Sensor Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Nathan S. Lewis

    1999-02-17

    This paper focuses on two main areas: understanding sensor response times so as to obtain improved time response in the field when needed for vapor tracking and classification, and improved theoretical understanding of the sensor response properties that generate the pattern on the array in response to a given analyte.

  1. A novel deconvolution beamforming algorithm for virtual phased arrays

    DEFF Research Database (Denmark)

    Fernandez Comesana, Daniel; Fernandez Grande, Efren; Tiana Roig, Elisabet;

    2013-01-01

    traditionally obtained using large arrays can be emulated by applying beamforming algorithms to data acquired from only two sensors. This paper presents a novel beamforming algorithm which uses a deconvolution approach to strongly reduce the presence of side lobes. A series of synthetic noise sources...

  2. Root crack sizing using phased array inspections and autoregressive spectral extrapolation signal processing

    Science.gov (United States)

    Caldwell, J.; Shakibi, B.; Moles, M.; Sinclair, A. N.

    2013-01-01

    Phased array inspection was conducted on a V-butt welded steel sample with multiple shallow flaws of varying depths. The inspection measurements were processed using Wiener filtering and Autoregressive Spectral Extrapolation (AS) to enhance the signals. Phased array inspections were conducted using multiple phased array probes of varying nominal central frequencies (2.25, 4, 5 and 10 MHz). This paper describes the measured results, which show high accuracy, typically in the range of 0.1-0.2 mm. The results concluded that: 1. There was no statistical difference between the calculated flaw depths from phased array inspections at different flaw tip angles. 2. There was no statistical difference in flaw depths calculated using phased array data collected from either side of the weld. 3. Flaws with depths less than the estimated probe signal shear wavelength could not be sized. 4. Finally, there was no statistical difference in the calculated flaw depths using phased array probes with different sampling frequencies and destructive measurements of the flaws.

  3. An analytical filter design method for guided wave phased arrays

    Science.gov (United States)

    Kwon, Hyu-Sang; Kim, Jin-Yeon

    2016-12-01

    This paper presents an analytical method for designing a spatial filter that processes the data from an array of two-dimensional guided wave transducers. An inverse problem is defined where the spatial filter coefficients are determined in such a way that a prescribed beam shape, i.e., a desired array output is best approximated in the least-squares sense. Taking advantage of the 2π-periodicity of the generated wave field, Fourier-series representation is used to derive closed-form expressions for the constituting matrix elements. Special cases in which the desired array output is an ideal delta function and a gate function are considered in a more explicit way. Numerical simulations are performed to examine the performance of the filters designed by the proposed method. It is shown that the proposed filters can significantly improve the beam quality in general. Most notable is that the proposed method does not compromise between the main lobe width and the sidelobe levels; i.e. a narrow main lobe and low sidelobes are simultaneously achieved. It is also shown that the proposed filter can compensate the effects of nonuniform directivity and sensitivity of array elements by explicitly taking these into account in the formulation. From an example of detecting two separate targets, how much the angular resolution can be improved as compared to the conventional delay-and-sum filter is quantitatively illustrated. Lamb wave based imaging of localized defects in an elastic plate using a circular array is also presented as an example of practical applications.

  4. Optical Phased Array Using Guided Resonance with Backside Reflectors

    Science.gov (United States)

    Horie, Yu (Inventor); Arbabi, Amir (Inventor); Faraon, Andrei (Inventor)

    2016-01-01

    Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.

  5. Circumferential phased array of shear-horizontal wave magnetostrictive patch transducers for pipe inspection.

    Science.gov (United States)

    Kim, Hoe Woong; Lee, Joo Kyung; Kim, Yoon Young

    2013-02-01

    Several investigations report effective uses of magnetostrictive patch transducers to generate and measure longitudinal and torsional guided waves in a pipe. They can be used to form a phased array for the circumferential inspection of pipes. Although there are circumferential phased arrays employing piezoelectric transducers or EMAT's, no magnetostrictive patch transducer based array system has been attempted. In this investigation, we aim to develop a circumferential phased magnetostrictive patch transducer (PMPT) array that can focus shear-horizontal waves at any target point on a cylindrical surface of a pipe. For the development, a specific configuration of a PMPT array employing six magnetostrictive patch transducers is proposed. A wave simulation model is also developed to determine time delays and amplitudes of signals generated by the transducers of the array. This model should be able to predict accurately the angular profiles of shear-horizontal waves generated by the transducers. For wave focusing, the time reversal idea will be utilized. The wave focusing ability of the developed PMPT array is tested with multiple-crack detection experiments. Imaging of localized surface inspection regions is also attempted by using wave signals measured by the developed PMPT array system.

  6. Controlling gradient phase distributions in a model of active antenna array with locally coupled elements

    Science.gov (United States)

    Mishagin, K. G.; Shalfeev, V. D.

    2006-12-01

    The regime of synchronization with a certain gradient phase distribution and the possibility of controlling such distribution in a linear array of oscillators coupled by phase-locked loops (PLLs) have been theoretically studied. It is shown that a constant phase progression can be controlled by manipulating collective dynamics, with oscillator eigenfrequencies and coupling coefficients being the control parameters. The proposed principle of control, based on the nonlinear dynamics of PLL-coupled oscillators, can be used in solving the problems of phasing and controlled beam scanning in antenna arrays operating in different frequency bands.

  7. An Optimal Beamforming Algorithm for Phased-Array Antennas Used in Multi-Beam Spaceborne Radiometers

    DEFF Research Database (Denmark)

    Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.

    2015-01-01

    Strict requirements for future spaceborne ocean missions using multi-beam radiometers call for new antenna technologies, such as digital beamforming phased arrays. In this paper, we present an optimal beamforming algorithm for phased-array antenna systems designed to operate as focal plane arrays...... (FPA) in push-broom radiometers. This algorithm is formulated as an optimization procedure that maximizes the beam efficiency, while minimizing the side-lobe and cross-polarization power in the area of Earth, subject to a constraint on the beamformer dynamic range. The proposed algorithm is applied...

  8. Monolithic microwave integrated circuits for sensors, radar, and communications systems; Proceedings of the Meeting, Orlando, FL, Apr. 2-4, 1991

    Science.gov (United States)

    Leonard, Regis F. (Editor); Bhasin, Kul B. (Editor)

    1991-01-01

    Consideration is given to MMICs for airborne phased arrays, monolithic GaAs integrated circuit millimeter wave imaging sensors, accurate design of multiport low-noise MMICs up to 20 GHz, an ultralinear low-noise amplifier technology for space communications, variable-gain MMIC module for space applications, a high-efficiency dual-band power amplifier for radar applications, a high-density circuit approach for low-cost MMIC circuits, coplanar SIMMWIC circuits, recent advances in monolithic phased arrays, and system-level integrated circuit development for phased-array antenna applications. Consideration is also given to performance enhancement in future communications satellites with MMIC technology insertion, application of Ka-band MMIC technology for an Orbiter/ACTS communications experiment, a space-based millimeter wave debris tracking radar, low-noise high-yield octave-band feedback amplifiers to 20 GHz, quasi-optical MESFET VCOs, and a high-dynamic-range mixer using novel balun structure.

  9. Monolithic CMOS pixel detector for international linear collider vertex detection

    Indian Academy of Sciences (India)

    J E Brau; O Igonkina; N Sinew; D Strom; C Baltay; W Emmet; H Neal; D Rabinowitz

    2007-12-01

    A monolithic CMS pixel detector is under development for an ILC experiment. This chronopixel array provides a time stamp resolution of one bunch crossing, a critical feature for background suppression. The status of this effort is summarized.

  10. Phase-locked array of quantum cascade lasers with an intracavity spatial filter

    CERN Document Server

    Wang, Lei; Jia, Zhiwei; Zhao, Yue; Liu, Chuanwei; Liu, Yinghui; Zhai, Shenqiang; Ning, Zhuo; Liu, Fengqi

    2016-01-01

    Phase-locking an array of quantum cascade lasers is an effective way to achieve higher output power and beam shaping. In this article, based on Talbot effect, we show a new-type phase-locked array of mid-infrared quantum cascade lasers with an integrated spatial- filtering Talbot cavity. All the arrays show stable in-phase operation from the threshold current to full power current. The beam divergence of the array device is smaller than that of a single-ridge laser. We use the multi-slit Fraunhofer diffraction mode to interpret the far-field radiation profile and give a solution to get better beam quality. The maximum power is just about 5 times that of a single-ridge laser for eleven-laser array device and 3 times for seven-laser array device. Considering the great modal selection ability, simple fabricating process and the potential for achieving better beam quality and smaller cavity loss, this new-type phase-locked array may be a hopeful and elegant solution to get high power or beam shaping.

  11. Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

    Science.gov (United States)

    Zhou, Guoquan

    2011-11-21

    A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail.

  12. Tolerances for Phase Locking of Semiconductor Laser Arrays.

    Science.gov (United States)

    1988-04-18

    laser fabrication . This means that the starting material is critically important to tne success of locked laser arrays. F. TOLERANCE REQUIREMENTS ON...typically r , 0.1. Because Eq. (7) represents a small frequency deviation, and implies A - 0.5 4, this report will look into the tolerances on laser ... fabrication and operation to ensure that the free-running laser frequencies remain within this locking range. D. COMPARISON OF LOCKING CONDITION WITH

  13. Investigation of the Sequential Rotation Technique and its Application in Phased Arrays

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal

    2007-01-01

    This report documents the investigations of the sequential rotation technique in application to phased array antennas. A spherical wave expansion for the far field of sequentially phased arrays is derived for general antenna elements. This model is approximate in that it assumes that the element...... patterns are identical and it does not included the effects of mutual coupling between the elements. For this reason it is compared with more accurate numerical models which include the coupling effects. The results show that the sequential rotation technique generally improves the performance...... of the phased array also when it is scanned off bore sight. For array topologies where the elements are not positioned rotationally symmetric the performance of the sequential rotation is to some extent impaired by the mutual coupling and non-identical element patterns. These effects are not evident from...

  14. A Novel Monopulse Technique for Adaptive Phased Array Radar

    Directory of Open Access Journals (Sweden)

    Xinyu Zhang

    2017-01-01

    Full Text Available The monopulse angle measuring technique is widely adopted in radar systems due to its simplicity and speed in accurately acquiring a target’s angle. However, in a spatial adaptive array, beam distortion, due to adaptive beamforming, can result in serious deterioration of monopulse performance. In this paper, a novel constrained monopulse angle measuring algorithm is proposed for spatial adaptive arrays. This algorithm maintains the ability to suppress the unwanted signals without suffering from beam distortion. Compared with conventional adaptive monopulse methods, the proposed algorithm adopts a new form of constraint in forming the difference beam with the merit that it is more robust in most practical situations. At the same time, it also exhibits the simplicity of one-dimension monopulse, helping to make this algorithm even more appealing to use in adaptive planar arrays. The theoretical mean and variance of the proposed monopulse estimator is derived for theoretical analysis. Mathematical simulations are formulated to demonstrate the effectiveness and advantages of the proposed algorithm. Both theoretical analysis and simulation results show that the proposed algorithm can outperform the conventional adaptive monopulse methods in the presence of severe interference near the mainlobe.

  15. Integrated optical phased array based large angle beam steering system fabricated on silicon-on-insulator

    Science.gov (United States)

    Kwong, David N.; Zhang, Yang; Hosseini, Amir; Chen, Ray T.

    2011-01-01

    In this paper, we present a highly compact silicon nano-membrane based optical phased array fabricated using conventional CMOS processing on silicon-on-insulator that provides for over 10 degrees of beam steering in a silicon slab at λ=1.55μm using transverse-electrical polarized light. A low loss 1-to-12 multi-mode interference (MMI) optical beam splitter with high uniformity is used to provide inputs to the optical phased array. Using an unequally spaced waveguide array permits us to relax the half-wavelength spacing requirement for large angle beam steering, thereby avoiding the optical coupling between adjacent waveguides and reducing the side-lobe-level of the array radiation pattern. S-bend waveguides convert the equally spaced MMI output to the unequally spaced wave guide array, while passively equalizing the phases of each array element to compensate for the MMI output phase profile. Independently controllable thin film metal heaters are used to achieve phase shifting using the strong thermo-optic response of silicon. Heat-insulating air grooves minimize thermal crosstalk, while also achieving and low power consumption.

  16. Hydrophobic-hydrophilic monolithic dual-phase layer for two-dimensional thin-layer chromatography coupled with surface-enhanced Raman spectroscopy detection.

    Science.gov (United States)

    Zheng, Binxing; Liu, Yanhua; Li, Dan; Chai, Yifeng; Lu, Feng; Xu, Jiyang

    2015-08-01

    Hydrophobic-hydrophilic monolithic dual-phase plates have been prepared by a two-step polymerization method for two-dimensional thin-layer chromatography of low-molecular-weight compounds, namely, several dyes. The thin 200 μm poly(glycidyl methacrylate-co-ethylene dimethacrylate) layers attached to microscope glass plates were prepared using a UV-initiated polymerization method within a simple glass mold. After cutting and cleaning the specific area of the layer, the reassembled mold was filled with a polymerization mixture of butyl methacrylate and ethylene dimethacrylate and subsequently irradiated with UV light. During the second polymerization process, the former layer was protected from the UV light with a UV mask. After extracting the porogens and hydrolyzing the poly(glycidyl methacrylate-co-ethylene dimethacrylate) area, these two-dimensional layers were used to separate a mixture of dyes with great difference in their polarity using reversed-phase chromatography mode within the hydrophobic layer and then hydrophilic interaction chromatography mode along the hydrophilic area. In the latter dimension only the specific spot was developed further. Detection of the separated dyes could be achieved with surface-enhanced Raman spectroscopy.

  17. Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation

    Institute of Scientific and Technical Information of China (English)

    HOU Jing; XIAO Rui

    2006-01-01

    We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier (MOPA) configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved.It can be used not only to obtain high power fibre laser array but also in laser space communication.

  18. Measurement of Root-Mean-Square Phase Errors in Arrayed Waveguide Gratings

    Institute of Scientific and Technical Information of China (English)

    ZHENG Xiao-Ping; CHU Yuan-Liang; ZHAO Wei; ZHANG Han-Yi; GUO Yi-Li

    2004-01-01

    @@ The interference-based method to measure the root-mean-square phase errors in SiO2-based arrayed waveguide gratings (AWGs) is presented. The experimental results show that the rms phase error of the tested AWG is 0. 72 rad.

  19. Phased-Array Antenna Beam Squinting Related to Frequency Dependency of Delay Circuits

    NARCIS (Netherlands)

    Garakoui, S.K.; Klumperink, E.A.M.; Nauta, B.; Vliet, F.E. van

    2011-01-01

    Practical time delay circuits do not have a perfectly linear phase-frequency characteristic. When these delay circuits are applied in a phased-array system, this frequency dependency shows up as a frequency dependent beam direction (“beam squinting”). This paper quantifies beam squinting for a linea

  20. Spectral and picosecond temporal properties of flared guide Y-coupled phase-locked laser arrays

    Science.gov (United States)

    Defreez, R. K.; Bossert, D. J.; Yu, N.; Hartnett, K.; Elliott, R. A.

    1988-01-01

    Spatiospectral and spatiotemporal characteristics of flared waveguide Y-coupled laser arrays are studied for the cases of both CW and pulsed operation. Regular sustained self-pulsations were observed for both operation modes. It is suggested that the pulsations are due to the destabilization of phase locking which is caused by amplitude phase coupling.

  1. Solid-state retrodirective phased array concepts for microwave power transmission from Solar Power Satellite

    Science.gov (United States)

    Schroeder, K. G.; Petroff, I. K.

    1980-01-01

    Two prototype solid-state phased array systems concepts for potential use in the Solar Power Satellite are described. In both concepts, the beam is centered on the rectenna by means of phase conjugation of a pilot signal emanating from the ground. Also discussed is on-going solid-state amplifier development.

  2. A novel technique for electronic phasing of high power fiber amplifier arrays

    Science.gov (United States)

    Shay, T. M.; Baker, J. T.; Sanchez, Anthony D.; Robin, C. A.; Vergien, C. L.; Zeringue, C.; Gallant, D.; Lu, Chunte A.; Pulford, Benjamin; Bronder, T. J.; Lucero, Arthur

    2009-06-01

    We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently combined.

  3. Intelligent Motion Compensation for Improving the Tracking Performance of Shipborne Phased Array Radar

    Directory of Open Access Journals (Sweden)

    J. Mar

    2013-01-01

    Full Text Available The shipborne phased array radar must be able to compensate the ship’s motion and track the maneuvering targets automatically. In this paper, the real-time beam pointing error compensation mechanism of a planar array antenna for ship’s motion is designed to combine with the Kalman filtering. The effect of beam pointing error on the tracking performance of shipborne phased array radar is examined. A compensation mechanism, which can automatically correct the beam pointing error of the planar antenna array, is proposed for shipborne phased array radar in order to achieve the required tracking accuracy over the long dwell time. The automatic beam pointing error compensation mechanism employs the parallel fuzzy basis function network (FBFN architecture to estimate the beam pointing error caused by roll and pitch of the ship. In the simulation, the models of roll and pitch are used to evaluate the performance of beam pointing error estimation mechanism based on the proposed parallel FBFN architecture. In addition, the effect of automatic beam pointing error compensation mechanism on the tracking performance of adaptive extended Kalman filter (AEKF implemented in ship borne phased array radar is also investigated. Simulations find out that the proposed algorithms are stable and accurate.

  4. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

    2010-12-15

    Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

  5. High speed, high power one-dimensional beam steering from a 6-element optical phased array.

    Science.gov (United States)

    Huang, W Ronny; Montoya, Juan; Kansky, Jan E; Redmond, Shawn M; Turner, George W; Sanchez-Rubio, Antonio

    2012-07-30

    Beam steering at high speed and high power is demonstrated from a 6-element optical phased array using coherent beam combining (CBC) techniques. The steering speed, defined as the inverse of the time to required to sweep the beam across the steering range, is 40 MHz and the total power is 396 mW. The measured central lobe FWHM width is 565 μrad. High on-axis intensity is maintained periodically by phase-locking the array via a stochastic-parallel-gradient-descent (SPGD) algorithm. A master-oscillator-power-amplifier (MOPA) configuration is used where the amplifier array elements are semiconductor slab-coupled-optical-waveguide-amplifiers (SCOWAs). The beam steering is achieved by LiNbO(3) phase modulators; the phase-locking occurs by current adjustment of the SCOWAs. The system can be readily scaled to GHz steering speed and multiwatt-class output.

  6. Analytic phase-factor equations for Talbot array illuminations.

    Science.gov (United States)

    Zhou, C; Stankovic, S; Tschudi, T

    1999-01-10

    Under specific circumstances the fractional Talbot effect can be described by simplified equations. We have obtained simplified analytic phase-factor equations to describe the relation between the pure-phase factors and their fractional Talbot distances behind a binary amplitude grating with an opening ratio of (1/M). We explain how these simple equations are obtained from the regularly rearranged neighboring phase differences. We point out that any intensity distribution with an irreducible opening ratio (M(N)/M) (M(N) illumination in this case. Experimental verification of our theoretical results is given.

  7. Optoelectronic Infrastructure for RF/Optical Phased Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optoelectronic integrated holds the key to higher performance, reduced mass and radiation-hard space systems. A special need is increased flexibility of phased...

  8. Phase Centers of Subapertures in a Tapered Aperture Array.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  9. Study on Clutter Model and Characteristics of Airborne Radar with Parabolic Conformal Phased Array

    Institute of Scientific and Technical Information of China (English)

    Hao Jiang; Nini Rao; Xingbo Chen; Jiabin Zhou; Chaoyang Qiu; Wen Zhai; Zhimei Hao

    2016-01-01

    The studies on clutter modeling and suppression of airborne radar with a parabolic conformal array are uncommon due to the complexity of this type of antenna array configuration. The correct understanding of clutter characteristics for airborne radar with a parabolic conformal antenna array is the prerequisite and foundation of optimal suppression of this type of clutter. This paper establishes the model of clutter echo of airborne parabolic conformal phased array radar and analyzes the structure characteristics and the distribution features of this type of clutter. The simulation results show that this type of clutter has the following characteristics: 1) The main lobe on the azimuth is seriously broadened, 2) the power spectrum presents strong heterogeneity, and 3) the freedom degrees are high. Based on the existing related clutter suppression methods, we verified the correctness of the constructed clutter model. This work has an important guidance to further study on clutter suppression methods in airborne parabolic conformal array radar.

  10. Measuring Phased-Array Antenna Beampatterns with High Dynamic Range for the Murchison Widefield Array using 137 MHz ORBCOMM Satellites

    CERN Document Server

    Neben, A R; Hewitt, J N; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Deshpande, A A; Goeke, R; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Kaplan, D L; Lonsdale, C J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Wayth, R B; Webster, R L; Williams, A; Williams, C L

    2015-01-01

    Detection of the fluctuations in 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the {\\it in situ} beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering), and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second reference dipole. We achieve beam measurements over 30 dB dynamic range in beam...

  11. Design and Realization of Phased Array Radar Optical Fiber Transmission System

    Institute of Scientific and Technical Information of China (English)

    HU Shan-qing; LIU Feng; LONG Teng

    2007-01-01

    One optical fiber transmission system is designed.The modularization optical fiber transmission adapters were utilized in the system,so the system structure could be flexibly scalable.The sub-array adapter and signal processor adapter were designed and realized utilizing the new field programmable gate array (FPGA) which could drive the optical transceiver.The transmission agreement was designed based on the data stream.In order to solve the signal synchronization problem of the optical fiber transmitted phased array radar,a method named synchronous clock was designed.The fiber transmission error code rate of the system was zero with an experimental transmission velocity of 800 Mbit/s.The phased array radar system has detected the airplane target,thus validated the feasibility of the design method.

  12. Phased arrays: A strategy to lower the energy threshold for neutrinos

    Directory of Open Access Journals (Sweden)

    Wissel Stephanie

    2017-01-01

    Full Text Available In-ice radio arrays are optimized for detecting the highest energy, cosmogenic neutrinos expected to be produced though cosmic ray interactions with background photons. However, there are two expected populations of high energy neutrinos: the astrophysical flux observed by IceCube (~1 PeV and the cosmogenic flux (~ 1017 eV or 100 PeV. Typical radio arrays employ a noise-riding trigger, which limits their minimum energy threshold based on the background noise temperature of the ice. Phased radio arrays could lower the energy threshold by combining the signals from several channels before triggering, thereby improving the signal-to-noise at the trigger level. Reducing the energy threshold would allow radio experiments to more efficiently overlap with optical Cherenkov neutrino telescopes as well as for more efficient searches for cosmogenic neutrinos. We discuss the proposed technique and prototypical phased arrays deployed in an anechoic chamber and at Greenland’s Summit Station.

  13. Performance of a mmWave beamformed phased array system for indoor LOS communication

    Science.gov (United States)

    Amjad, Kinnan; Xu, Huaping

    2016-11-01

    Millimeter waves (mmWaves) spectrum ranging from 30GHz to 300GHz is emerging as a potential solution to the bandwidth problem faced by the wireless communication now a days. The advancements in the antenna technology has enabled the fabrication of antenna arrays or phased array systems which when used with techniques like spatial multiplexing and beamforming has enabled the use of mmWaves for both indoor and outdoor communication systems by providing gain and selectivity. This has also opened the doors for its potential use in long range and cellular communications. The 60GHz band also know as the oxygen absorption band due to its higher attenuation and unlicensed operation is a good candidate for use in secure and confined communications. In this paper we have investigated the performance of a beamformed phased array system in the mmWave spectrum. The performance is measured for varying the source and noise location and compared for a Linear and Rectangular array.

  14. Monolithic Fuel Fabrication Process Development

    Energy Technology Data Exchange (ETDEWEB)

    C. R. Clark; N. P. Hallinan; J. F. Jue; D. D. Keiser; J. M. Wight

    2006-05-01

    The pursuit of a high uranium density research reactor fuel plate has led to monolithic fuel, which possesses the greatest possible uranium density in the fuel region. Process developments in fabrication development include friction stir welding tool geometry and cooling improvements and a reduction in the length of time required to complete the transient liquid phase bonding process. Annealing effects on the microstructures of the U-10Mo foil and friction stir welded aluminum 6061 cladding are also examined.

  15. Simulation Based Investigation of Focusing Phased Array Ultrasound in Dissimilar Metal Welds

    Directory of Open Access Journals (Sweden)

    Hun-Hee Kim

    2016-02-01

    Full Text Available Flaws at dissimilar metal welds (DMWs, such as reactor coolant systems components, Control Rod Drive Mechanism (CRDM, Bottom Mounted Instrumentation (BMI etc., in nuclear power plants have been found. Notably, primary water stress corrosion cracking (PWSCC in the DMWs could cause significant reliability problems at nuclear power plants. Therefore, phased array ultrasound is widely used for inspecting surface break cracks and stress corrosion cracks in DMWs. However, inspection of DMWs using phased array ultrasound has a relatively low probability of detection of cracks, because the crystalline structure of welds causes distortion and splitting of the ultrasonic beams which propagates anisotropic medium. Therefore, advanced evaluation techniques of phased array ultrasound are needed for improvement in the probability of detection of flaws in DMWs. Thus, in this study, an investigation of focusing and steering phased array ultrasound in DMWs was carried out using a time reversal technique, and an adaptive focusing technique based on finite element method (FEM simulation. Also, evaluation of focusing performance of three different focusing techniques was performed by comparing amplitude of phased array ultrasonic signals scattered from the targeted flaw with three different time delays.

  16. Theoretical study of acoustic field patterns of 2-D ultrasound phased arrays for hyperthermia therapy

    Institute of Scientific and Technical Information of China (English)

    HUO Jian; ZHANG Wei; SHI Keren

    2005-01-01

    Acoustic field patterns of 2-D ultrasound phased arrays for the high intensity focused ultrasound (HIFU) hyperthermia therapy are studied, and controlling algorithms of field patterns are provided. The 2-D phased array using the conventional single-focus scanning pattern can exactly control the focal distance and the steering direction of the beam, but in general produce a single focus. Extremely high intensity levels will be needed when this pattern is used to treat large tumors. However, a direct synthesis method of the acoustic field based on the pseudo-inverse matrix can produce the multiple-focus field pattern. The rectangular radiator method of the acoustic field was used to simulate the single-focus scanning pattern and the multiple-focus pattern which are produced by a 2-D phased array consisting of 20×20 elements,and simulation results show that the 2-D array using the multiple-focus pattern can produce several foci with lower intensity levels simultaneously. Furthermore, the improved eigenvector algorithm was used to optimize the intensity gain of the multiple-focus pattern. It is shown to increase the power deposition in the target volume and eliminate the undesired interference.And the multiple-focus pattern also allows the complex excitation vector to be weighted to increase the array excitation efficiency, and therefore we can only control the phase distribution of the excitation vector to realize the phase-only multiple-focus pattern synthesis.

  17. Imaging Properties of Planar Microlens Arrays

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The planar microlens arrays is a two-dimensional array of optical component which is fabricated monolithically available. Imaging properties of planar microlens arrays are described, which provide both image multiplexer and erect, unit magnification images.

  18. Nanosecond monolithic CMOS readout cell

    Science.gov (United States)

    Souchkov, Vitali V.

    2004-08-24

    A pulse shaper is implemented in monolithic CMOS with a delay unit formed of a unity gain buffer. The shaper is formed of a difference amplifier having one input connected directly to an input signal and a second input connected to a delayed input signal through the buffer. An elementary cell is based on the pulse shaper and a timing circuit which gates the output of an integrator connected to the pulse shaper output. A detector readout system is formed of a plurality of elementary cells, each connected to a pixel of a pixel array, or to a microstrip of a plurality of microstrips, or to a detector segment.

  19. Collaborative Randomized Beamforming for Phased Array Radio Interferometers

    CERN Document Server

    Ocal, Orhan; Cherubini, Giovanni; Kazemi, Sanaz

    2014-01-01

    The Square Kilometre Array (SKA) will form the largest radio telescope ever built and such a huge instrument in the desert poses enormous engineering and logistic challenges. Algorithmic and architectural breakthroughs are needed. Data is collected and processed in groups of antennas before transport for central processing. This processing includes beamforming, primarily so as to reduce the amount of data sent. The principal existing technique points to a region of interest independently of the sky model and how the other stations beamform. We propose a new collaborative beamforming algorithm in order to maximize information captured at the stations (thus reducing the amount of data transported). The method increases the diversity in measurements through randomized beam- forming. We demonstrate through numerical simulation the effectiveness of the method. In particular, we show that randomized beamforming can achieve the same image quality while producing 40% less data when compared to the prevailing method m...

  20. Multi-Step Amplitude Quantization for Ultralow Sidelobe Phased Arrays by Direct Optimization Synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, a new amplitude quautization synthesis method for ultraiow sidelobe phased arrays is proposed,which is based on the constrained nonlinear optimization algorithm. By introducing a set of critical constraint conditionsinto the optimization model, we can directly quantize the amplitude distribution instead of replacing it with a continuousequivalent aperture antenne The mutual coupling and the element patterns are also considered in the quantizationsynthesis. Finally, some array simulation results are given to show the effectiveness of the method.

  1. Experimental Demonstration of Array-level Learning with Phase Change Synaptic Devices

    OpenAIRE

    Eryilmaz, S. Burc; Kuzum, Duygu; Jeyasingh, Rakesh G. D.; Kim, SangBum; BrightSky, Matthew; Lam, Chung; Wong, H.-S. Philip

    2014-01-01

    The computational performance of the biological brain has long attracted significant interest and has led to inspirations in operating principles, algorithms, and architectures for computing and signal processing. In this work, we focus on hardware implementation of brain-like learning in a brain-inspired architecture. We demonstrate, in hardware, that 2-D crossbar arrays of phase change synaptic devices can achieve associative learning and perform pattern recognition. Device and array-level ...

  2. A K/Ka band radiating element for Tx/Rx phased array

    KAUST Repository

    Sandhu, Ali Imran

    2017-01-20

    The paper presents a K/Ka band radiating element for TX/RX phased arrays. Dual band operations is obtained using a single radiating surface: a novel radiator is adopted and placed in a configuration in which dual band and single band elements are interleaved. The array elements are optimized to scan the beam in excess of 50° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

  3. Monolithic molecular imprinted polymer fiber for recognition and solid phase microextraction of ephedrine and pseudoephedrine in biological samples prior to capillary electrophoresis analysis.

    Science.gov (United States)

    Deng, Dong-Li; Zhang, Ji-You; Chen, Chen; Hou, Xiao-Ling; Su, Ying-Ying; Wu, Lan

    2012-01-01

    A novel capillary electrophoresis (CE) method coupled with monolithic molecular imprinted polymer (MIP) fiber based solid phase microextraction (SPME) was developed for selective and sensitive determination of ephedrine (E) and pseudoephedrine (PE). With in situ polymerization in a silica capillary mold and E as template, the MIP fibers could be produced in batch reproducibly and each fiber was available for 50 extraction cycles without significant decrease in extraction ability. Using the MIP fiber under optimized extraction conditions, CE detection limits of E and PE were greatly lowered from 0.20 to 0.00096 μg/mL and 0.12 to 0.0011 μg/mL, respectively. Analysis of urine and serum samples by the MIP-SPME-CE method was also performed, with results indicating that E and PE could be selectively extracted. The recoveries and relative standard deviations (RSDs) for sample analysis were found in the range of 91-104% and 3.8-9.1%, respectively.

  4. The new JET phased ICRH array: first experiments and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bures, M.; Bhatnagar, V.; Brown, T.; Fechner, B.; Gormezano, C.; Kaye, A.; Lennholm, M.; Righi, E.; Rimini, F.; Sibley, A.; Start, D.; Wade, T. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Goulding, R. [Oak Ridge National Lab., TN (United States); Lamalle, P. [Ecole Royale Militaire, Brussels (Belgium). Lab. de Physique des Plasmas; Nguyen, F. [CEA Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France)

    1994-07-01

    New ICRH antennas on JET were designed to couple to the new JET divertor plasma configurations and to improve the Fast Wave Current Drive (FWCD) capabilities. The A2 antenna consists of 4 straps whose currents can be phased at arbitrary angles. The real time automatic tuning acts on frequency, line length (line phase shifters) and stub length. Provision is made for the coupling resistance/plasma position feedback to accommodate the fast changes in antenna loading. The first coupling, tuning and heating results are reported in 0{pi}0{pi}, 0000 and 00{pi}{pi} phasing. A new antenna model is described, which was developed to simulate the measured antenna loading in terms of plasma parameters and to provide a starting point for the real time automatic tuning. 5 refs., 4 figs.

  5. The radiated fields of focussing air-coupled ultrasonic phased arrays.

    Science.gov (United States)

    Neild, A; Hutchins, D A; Robertson, T J; Davis, L A J; Billson, D R

    2005-01-01

    This paper presents an investigation into the fields radiated into air by ultrasonic phased arrays under transient excitation. In particular, it includes a theoretical prediction of spatial variations in amplitude throughout the both the near-field and far-field of such arrays. The approach has been used to predict the result of phasing to produce a focus in air, which can be seen to be particularly effective in the near-field of the array. Interesting features are observed, which are then described in terms of the performance of both individual elements and the resulting array. It is shown how some elements of design can be used to improve performance in focussing. The predictions are compared to the results of experiments in air using electrostatic arrays, where good focussing could be achieved provided the appropriate design principles were followed. The approach has been developed specifically for use in air, but the results would also hold for modelling in certain medical arrays where a focussing requirement might be needed close to the array itself.

  6. Analysis of Circularly Polarized Hemispheroidal Dielectric Resonator Antenna Phased Arrays Using the Method of Auxiliary Sources

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2007-01-01

    The method of auxiliary sources is employed to model and analyze probe-fed hemispheroidal dielectric resonator antennas and arrays. Circularly polarized antenna elements of different designs are analyzed, and impedance bandwidths of up to 14.7% are achieved. Selected element designs are subsequen...... are subsequently employed in a seven-element phased array. The array performance is analyzed with respect to scan loss and main beam directivity as a function of scan angle and frequency, and the influence of element separation is investigated....

  7. Towards the development of a high-sensitivity cryogenic phased array feed

    Science.gov (United States)

    Roshi, D. A.; Warnick, K. F.; Brandt, J.; Fisher, J. R.; Ford, P.; Jeffs, B. D.; Marganian, P.; McLeod, M.; Mello, M.; Morgan, M.; Norrod, R.; Shillue, W.; Simon, R.; White, S.

    2014-08-01

    A cryogenic phased array feed operating at L-band is in development for the Green Bank Telescope (GBT). The feed consists of electrically small feed elements optimized for active impedance matching to cooled front end low noise amplifiers (LNAs), down-converters, a real-time streaming data acquisition system, and beamforming algorithms applied in post-processing. A prototype cryogenic array feed was recently tested on the GBT. This results will be an important step towards the development of a new receiver instrument, the focal L-band array for the GBT (FLAG).

  8. Automated Array Assembly, Phase 2. Low-cost Solar Array Project, Task 4

    Science.gov (United States)

    Lopez, M.

    1978-01-01

    Work was done to verify the technological readiness of a select process sequence with respect to satisfying the Low Cost Solar Array Project objectives of meeting the designated goals of $.50 per peak watt in 1986 (1975 dollars). The sequence examined consisted of: (1) 3 inches diameter as-sawn Czochralski grown 1:0:0 silicon, (2) texture etching, (3) ion implanting, (4) laser annealing, (5) screen printing of ohmic contacts and (6) sprayed anti-reflective coatings. High volume production projections were made on the selected process sequence. Automated processing and movement of hardware at high rates were conceptualized to satisfy the PROJECT's 500 MW/yr capability. A production plan was formulated with flow diagrams integrating the various processes in the cell fabrication sequence.

  9. Wavefront sensing and adaptive control in phased array of fiber collimators

    Science.gov (United States)

    Lachinova, Svetlana L.; Vorontsov, Mikhail A.

    2011-03-01

    A new wavefront control approach for mitigation of atmospheric turbulence-induced wavefront phase aberrations in coherent fiber-array-based laser beam projection systems is introduced and analyzed. This approach is based on integration of wavefront sensing capabilities directly into the fiber-array transmitter aperture. In the coherent fiber array considered, we assume that each fiber collimator (subaperture) of the array is capable of precompensation of local (onsubaperture) wavefront phase tip and tilt aberrations using controllable rapid displacement of the tip of the delivery fiber at the collimating lens focal plane. In the technique proposed, this tip and tilt phase aberration control is based on maximization of the optical power received through the same fiber collimator using the stochastic parallel gradient descent (SPGD) technique. The coordinates of the fiber tip after the local tip and tilt aberrations are mitigated correspond to the coordinates of the focal-spot centroid of the optical wave backscattered off the target. Similar to a conventional Shack-Hartmann wavefront sensor, phase function over the entire fiber-array aperture can then be retrieved using the coordinates obtained. The piston phases that are required for coherent combining (phase locking) of the outgoing beams at the target plane can be further calculated from the reconstructed wavefront phase. Results of analysis and numerical simulations are presented. Performance of adaptive precompensation of phase aberrations in this laser beam projection system type is compared for various system configurations characterized by the number of fiber collimators and atmospheric turbulence conditions. The wavefront control concept presented can be effectively applied for long-range laser beam projection scenarios for which the time delay related with the double-pass laser beam propagation to the target and back is compared or even exceeds the characteristic time of the atmospheric turbulence change

  10. PMN-PT single-crystal high-frequency kerfless phased array.

    Science.gov (United States)

    Chen, Ruimin; Cabrera-Munoz, Nestor E; Lam, Kwok Ho; Hsu, Hsiu-sheng; Zheng, Fan; Zhou, Qifa; Shung, K Kirk

    2014-06-01

    This paper reports the design, fabrication, and characterization of a miniature high-frequency kerfless phased array prepared from a PMN-PT single crystal for forward-looking intravascular or endoscopic imaging applications. After lapping down to around 40 μm, the PMN-PT material was utilized to fabricate 32-element kerfless phased arrays using micromachining techniques. The aperture size of the active area was only 1.0 × 1.0 mm. The measured results showed that the array had a center frequency of 40 MHz, a bandwidth of 34% at -6 dB with a polymer matching layer, and an insertion loss of 20 dB at the center frequency. Phantom images were acquired and compared with simulated images. The results suggest that the feasibility of developing a phased array mounted at the tip of a forward-looking intravascular catheter or endoscope. The fabricated array exhibits much higher sensitivity than PZT ceramic-based arrays and demonstrates that PMN-PT is well suited for this application.

  11. Experience in applying technical UT phased array inspection pipe semiautomatic; Experiencia en la aplicacion de tecnica UT phased array a la inspeccion semiatomatica de tuberias

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Ruiz, M. A.

    2014-07-01

    In the framework of different projects of thickness measurement of Corrosion by Mycobacteria in pipelines of nuclear installations both Erosion/Corrosion phenomena, and in view that works ultrasonically carried out manually extend in time and require several stages of re-verification of the results obtained, it became necessary to develop a semiautomatic system ultrasonic measuring phased array with the aim of increasing the effectiveness of the System measuring both time and interpretation of results. (Author)

  12. Global phase synchronization in an array of time-delay systems.

    Science.gov (United States)

    Suresh, R; Senthilkumar, D V; Lakshmanan, M; Kurths, J

    2010-07-01

    We report the identification of global phase synchronization (GPS) in a linear array of unidirectionally coupled Mackey-Glass time-delay systems exhibiting highly non-phase-coherent chaotic attractors with complex topological structure. In particular, we show that the dynamical organization of all the coupled time-delay systems in the array to form GPS is achieved by sequential synchronization as a function of the coupling strength. Further, the asynchronous ones in the array with respect to the main sequentially synchronized cluster organize themselves to form clusters before they achieve synchronization with the main cluster. We have confirmed these results by estimating instantaneous phases including phase difference, average phase, average frequency, frequency ratio, and their differences from suitably transformed phase coherent attractors after using a nonlinear transformation of the original non-phase-coherent attractors. The results are further corroborated using two other independent approaches based on recurrence analysis and the concept of localized sets from the original non-phase-coherent attractors directly without explicitly introducing the measure of phase.

  13. Adhesive defect detection in composite adhesive joints using phased array transducers

    Science.gov (United States)

    Ren, Baiyang; Lissenden, Cliff J.

    2015-03-01

    Composite materials are widely used in aircraft structures due to their high specific stiffness and strength. The laminated nature of composite structures makes them subject to disbond and delamination. These types of defects will compromise the integrity of the structure and therefore need to be monitored. To monitor aircraft structures, light weight transducers capable of large area coverage are beneficial. Ultrasonic guided waves are able to travel long distance and are sensitive to localized defects. The multi-modal characteristic of propagating guided waves requires optimal mode selection and excitation. Phased array transducers provide good versatility for optimal mode excitation since they can excite different guided wave modes preferentially. Phased array transducers designed for structural health monitoring (SHM) applications are employed in this work to study the interaction between adhesive defects and guided wave modes. Amplitude ratios and wave packet composition are utilized as defect indicators that are uniquely available due to the phased array transducers.

  14. Nonparaxial multi-Gaussian beam models and measurement models for phased array transducers.

    Science.gov (United States)

    Zhao, Xinyu; Gang, Tie

    2009-01-01

    A nonparaxial multi-Gaussian beam model is proposed in order to overcome the limitation that paraxial Gaussian beam models lose accuracy in simulating the beam steering behavior of phased array transducers. Using this nonparaxial multi-Gaussian beam model, the focusing and steering sound fields generated by an ultrasonic linear phased array transducer are calculated and compared with the corresponding results obtained by paraxial multi-Gaussian beam model and more exact Rayleigh-Sommerfeld integral model. In addition, with help of this novel nonparaxial method, an ultrasonic measurement model is provided to investigate the sensitivity of linear phased array transducers versus steering angles. Also the comparisons of model predictions with experimental results are presented to certify the accuracy of this provided measurement model.

  15. Radiation Acoustic Field of a Linear Phased Array on a Cylindrical Surface

    Institute of Scientific and Technical Information of China (English)

    DENG Fang-Qing; ZHANG Bi-Xing; WANG Dong; SONG Gong-Pu

    2006-01-01

    A new linear ultrasonic phased array fixed on a cylindrical surface is designed. This kind of the cylindrical phased array can meet the specific requirements of the application in testing pipe quality inside pipes. Using the transducer, we can not only avoid mechanical rotating but also test the quality of any point in a pipe by ultrasonic phase array technology. The focused acoustic field distributions in the axial, radial and tangential directions of the transducer are investigated theoretically by numerical simulation. The energy flux density, the width of the main lobe, the imaging resolution, the grating lobe elimination and other characteristics are analysed. The effect of the focal distance, effective aperture, transducer radius, number of total element, and steering angle on the acoustic field distribution is also studied.thoroughly. Many important results are obtained.

  16. Standard guide for evaluating performance characteristics of phased-Array ultrasonic testing instruments and systems

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This guide describes procedures for evaluating some performance characteristics of phased-array ultrasonic examination instruments and systems. 1.2 Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this guide are expressed in terms that relate to their potential usefulness for ultrasonic examinations. Other electronic instrument characteristics in phased-array units are similar to non-phased-array units and may be measured as described in E 1065 or E 1324. 1.3 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated. 1.4 This guide establishes no performance limits for examination systems; if such acceptance criteria ar...

  17. The relationships between dispersion loss and sidelobe levels in wideband phased-array radars

    Science.gov (United States)

    Howard, Robert L., III; Belcher, Melvin L.; Corey, Larry E.

    Wideband phased-array radar systems experience significant problems created by frequency dispersion in the phased-array antenna. This phenomena has previously been studied for systems employing linear frequency modulation (LFM). LFM's vulnerability to deceptive electronic countermeasures (ECM) and signal-to-noise loss due to the amplitude weighting required to sufficiently suppress range sidelobes limit its usefulness. Pseudo-random noise (PRN) coded waveforms are capable of solving both these problems. This paper examines how the phased-array antenna affects the radar's performance when PRN coded waveforms are used. Issues of dispersion loss, grating lobe rejection, and compressed pulse shapes are considered. Where appropriate, results are compared to results from LFM systems. Sets of normalized curves are presented that quantify these effects in terms of signal bandwidth, subarray size, and antenna scan angle.

  18. Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array

    Science.gov (United States)

    Pignier, Nicolas J.; O'Reilly, Ciarán J.; Boij, Susann

    2017-04-01

    An application of phased array methods to numerical data is presented, aimed at identifying equivalent flow sound sources from aeroacoustic simulations. Based on phased array data extracted from compressible flow simulations, sound source strengths are computed on a set of points in the source region using phased array techniques assuming monopole propagation. Two phased array techniques are used to compute the source strengths: an approach using a Moore-Penrose pseudo-inverse and a beamforming approach using dual linear programming (dual-LP) deconvolution. The first approach gives a model of correlated sources for the acoustic field generated from the flow expressed in a matrix of cross- and auto-power spectral values, whereas the second approach results in a model of uncorrelated sources expressed in a vector of auto-power spectral values. The accuracy of the equivalent source model is estimated by computing the acoustic spectrum at a far-field observer. The approach is tested first on an analytical case with known point sources. It is then applied to the example of the flow around a submerged air inlet. The far-field spectra obtained from the source models for two different flow conditions are in good agreement with the spectra obtained with a Ffowcs Williams-Hawkings integral, showing the accuracy of the source model from the observer's standpoint. Various configurations for the phased array and for the sources are used. The dual-LP beamforming approach shows better robustness to changes in the number of probes and sources than the pseudo-inverse approach. The good results obtained with this simulation case demonstrate the potential of the phased array approach as a modelling tool for aeroacoustic simulations.

  19. Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

    Energy Technology Data Exchange (ETDEWEB)

    Le Bourdais, F.; Le Polles, T. [Non Destructive Testing Department at the French Atomic Energy Commission (CEA), Saclay, 91191 Gif sur Yvette CEDEX, (France); Baque, F. [Department of Sodium Technology at the French Atomic Energy Commission (CEA), Cadarache, 13108 St Paul lez Durance CEDEX, (France)

    2015-07-01

    This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

  20. Frequency-domain imaging algorithm for ultrasonic testing by application of matrix phased arrays

    Directory of Open Access Journals (Sweden)

    Dolmatov Dmitry

    2017-01-01

    Full Text Available Constantly increasing demand for high-performance materials and systems in aerospace industry requires advanced methods of nondestructive testing. One of the most promising methods is ultrasonic imaging by using matrix phased arrays. This technique allows to create three-dimensional ultrasonic imaging with high lateral resolution. Further progress in matrix phased array ultrasonic testing is determined by the development of fast imaging algorithms. In this article imaging algorithm based on frequency domain calculations is proposed. This approach is computationally efficient in comparison with time domain algorithms. Performance of the proposed algorithm was tested via computer simulations for planar specimen with flat bottom holes.

  1. Ultrasonic Phased Array Inspection for an Isogrid Structural Element with Cracks

    Science.gov (United States)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2010-01-01

    In this investigation, a T-shaped aluminum alloy isogrid stiffener element used in aerospace applications was inspected with ultrasonic phased array methods. The isogrid stiffener element had various crack configurations emanating from bolt holes. Computational simulation methods were used to mimic the experiments in order to help understand experimental results. The results of this study indicate that it is at least partly feasible to interrogate this type of geometry with the given flaw configurations using phased array ultrasonics. The simulation methods were critical in helping explain the experimental results and, with some limitation, can be used to predict inspection results.

  2. Ultrasonic Phased Array Inspection of Flaws on Weld Fusion Faces Using Full Matrix Capture

    Science.gov (United States)

    Long, R.; Russell, J.; Cawley, P.; Habgood, N.

    2009-03-01

    Work is being conducted to develop phased array inspection of stainless steel welded pipes. Ideally this uses waves reflected and mode converted at the inner surface of the pipe, but most commercial phased array controllers do not currently provide for this. Our solution was to use Full Matrix Capture (FMC) and process the data ourselves. This paper explains the FMC principle, describes the signal processing algorithms along with introducing the Almost Total Focusing Method (ATFM) and illustrates how the processed data was presented. The inspections were also modeled using the CEA CIVA software and compared to experimental results.

  3. Digitalization decoupling method and its application to the phased array in MRI

    Institute of Scientific and Technical Information of China (English)

    SONG Xiaoyu; WANG Weidong; ZHANG Bida; LEI Ming; BAO Shanglian

    2003-01-01

    A general network decoupling method for phased array radio frequency coil used in magnetic resonance imaging is developed. A more flexible digital approach further simplifies the method, which has an even higher signal-to-noise ratio. The performance of the digitalized decoupling method was confirmed by the calculated result by using a high frequency structure simulation software with the method of finite element for a tree-port phased array RF coil. The consistence was well established between the theoretical and simulated results.

  4. SCENARIO AND TARGET SIMULATION FOR A GROUND BASED MULTIFUNCTION PHASED ARRAY RADAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper describes a scenario and target simulation which operates in non real-time to provide full closed-loop operation of the ground based multifunction phased array radar simulation system in support of ballistic missile defence experiments against countermeasure.By simulating the target scattering signature and dynamical signature,this scenario and target simulation provide re- alistic scenario source to evaluate the system performance of multifunction phased array radar,and the key algorithms verification and validation such as target tracking,multi-target imaging and target recognition.

  5. Method for Fabricating and Packaging an M.Times.N Phased-Array Antenna

    Science.gov (United States)

    Subbaraman, Harish (Inventor); Xu, Xiaochuan (Inventor); Chen, Yihong (Inventor); Chen, Ray T. (Inventor)

    2017-01-01

    A method for fabricating an M.times.N, P-bit phased-array antenna on a flexible substrate is disclosed. The method comprising ink jet printing and hardening alignment marks, antenna elements, transmission lines, switches, an RF coupler, and multilayer interconnections onto the flexible substrate. The substrate of the M.times.N, P-bit phased-array antenna may comprise an integrated control circuit of printed electronic components such as, photovoltaic cells, batteries, resistors, capacitors, etc. Other embodiments are described and claimed.

  6. Phased Array Noise Source Localization Measurements Made on a Williams International FJ44 Engine

    Science.gov (United States)

    Podboy, Gary G.; Horvath, Csaba

    2010-01-01

    A 48-microphone planar phased array system was used to acquire noise source localization data on a full-scale Williams International FJ44 turbofan engine. Data were acquired with the array at three different locations relative to the engine, two on the side and one in front of the engine. At the two side locations the planar microphone array was parallel to the engine centerline; at the front location the array was perpendicular to the engine centerline. At each of the three locations, data were acquired at eleven different engine operating conditions ranging from engine idle to maximum (take off) speed. Data obtained with the array off to the side of the engine were spatially filtered to separate the inlet and nozzle noise. Tones occurring in the inlet and nozzle spectra were traced to the low and high speed spools within the engine. The phased array data indicate that the Inflow Control Device (ICD) used during this test was not acoustically transparent; instead, some of the noise emanating from the inlet reflected off of the inlet lip of the ICD. This reflection is a source of error for far field noise measurements made during the test. The data also indicate that a total temperature rake in the inlet of the engine is a source of fan noise.

  7. A Ka-band monolithic low phase noise coplanar waveguide oscillator using InAlAs/InGaAs HBT

    Science.gov (United States)

    Cui, Delong; Hsu, Shawn; Pavlidis, Dimitris; Chin, Patrick; Block, Tom

    2002-02-01

    A Ka-band oscillator has been designed, fabricated and tested using InAlAs/InGaAs HBTs. Coplanar waveguide technology has been employed to improve the Q-factor of the circuit. An output power of 2.6 dBm with DC to RF conversion efficiency of 7.8% was measured at 31.7 GHz. Low phase noise of -87 and -112 dBc/Hz were achieved at an offset frequency of 100 kHz and 1 MHz respectively. These low phase noise values can be attributed to the low 1/ f noise of the InAlAs/InGaAs HBT devices and the coplanar design used for the circuit.

  8. Atmospheric Phase Correction Using Total Power Radiometry at the Submillimeter Array

    CERN Document Server

    Battat, J B; Moran, J M; Paine, S; Battat, James B.; Blundell, Raymond; Moran, James M.; Paine, Scott

    2004-01-01

    Phase noise caused by an inhomogeneous, time-variable water vapor distribution in our atmosphere reduces the angular resolution, visibility amplitude and coherence time of millimeter and submillimeter wavelength interferometers. We present early results from our total power radiometry phase correction experiment carried out with the Submillimeter Array on Mauna Kea. From accurate measurements of the atmospheric emission along the lines of sight of two elements of the array, we estimated the differential atmospheric electrical path between them. In one test, presented here, the phase correction technique reduced the rms phase noise at 230 GHz from 72$\\degr$ to 27$\\degr$ over a 20 minute period with a 2.5 second integration time. This corresponds to a residual differential electrical path of 98 $\\mu$m, or 15 $\\mu$m of precipitable water vapor, and raises the coherence in the 20 minute period from 0.45 to 0.9.

  9. Theoretical and Experimental Investigation of Ultrasonic Focusing with Annular Phased Array

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bi-Xing; WANG Cheng-Hao; LAI Pu-Xiang

    2006-01-01

    @@ The focused acoustic field generated by an annular array transducer and its reflection field on a solid-liquid interface are investigated theoretically and experimentally. Theoretically, the concise analytic expressions about the radiation and reflection acoustic fields of the annular phased array are obtained by the ray approach method (saddle-point method). In experiment, an annular transducer with 8 equal-area elements is designed and fabricated, and a series of experiments about the radiation acoustic field and its reflection on the liquid-solid interface are carried out. The experimental characteristics of the transducer are in good agreement with the numerical ones. It shows the correctness of the theoretical result and the feasibility of dynamic focusing of the experiment system. With the maximum amplitude and its emergence time of the reflection wave, we can acquire the information and the imaging of the reflection interface by the annular phased array dynamic focusing.

  10. Synchronization of Chaotic Intensities and Phases in an Array of N Lasers

    Institute of Scientific and Technical Information of China (English)

    SUN Jian; ZHU Shi-Qun

    2005-01-01

    A linear array of N mutually coupled single-mode lasers is investigated. It is shown that the intensities of N lasers are chaotically synchronized when the coupling between lasers is relatively strong. The chaotic synchronization of intensities depends on the location of the lasers in the array. The chaotic synchronization appears between two outmost lasers, the second two outmost lasers, etc. There is no synchronization between nearest neighbors of the lasers. If the number of N is odd, the middle laser is never synchronized between any lasers. The chaotic synchronization of phases between nearest lasers in the array is examined by using the analytic signal and the Gaussian filter methods based on the peak of the power spectrum of the intensity. It can be seen that the message of chaotic intensity synchronization is conveyed through the phase synchronization.

  11. Quantum phase-slips in superconducting AlO{sub x} nanowire arrays at microwave frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Skacel, Sebastian T.; Pfirrmann, Marco; Voss, Jan N.; Muenzberg, Julian; Radtke, Lucas; Probst, Sebastian; Rotzinger, Hannes [Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany); Weides, Martin [Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany); Institute of Physics, Johannes Gutenberg University Mainz, D-55128 Mainz (Germany); Mooij, Hans E. [Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany); Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft (Netherlands); Ustinov, Alexey V. [Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe (Germany); Russian Quantum Center, 100 Novaya St., Skolkovo, Moscow region, 143025 (Russian Federation)

    2015-07-01

    Superconducting nanowires in the quantum phase slip (QPS) regime allow to study the flux and phase dynamics in duality to Josephson junction systems. However, due to the vanishing self-capacitance of the nanowires, the microwave response significantly differs. We experimentally study parallel arrays of nanowires which are embedded in a resonant circuit at GHz frequencies. The samples are probed at ultra-low microwave power and applied magnetic field at mK temperatures. The AlO{sub x} nanowires, with a sheet resistance in the kΩ range, are fabricated by sputter deposition of aluminium in a controlled oxygen atmosphere. The wires are defined with conventional electron beam lithography down to a width of approximately 15 nm. We present the fabrication of the nanowire arrays and measurement results for arrays coupled to superconducting microwave resonators.

  12. Synthesis of Phase-Only Reconfigurable Linear Arrays Using Multiobjective Invasive Weed Optimization Based on Decomposition

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2014-01-01

    Full Text Available Synthesis of phase-only reconfigurable array aims at finding a common amplitude distribution and different phase distributions for the array to form different patterns. In this paper, the synthesis problem is formulated as a multiobjective optimization problem and solved by a new proposed algorithm MOEA/D-IWO. First, novel strategies are introduced in invasive weed optimization (IWO to make original IWO fit for solving multiobjective optimization problems; then, the modified IWO is integrated into the framework of the recently well proved competitive multiobjective optimization algorithm MOEA/D to form a new competitive MOEA/D-IWO algorithm. At last, two sets of experiments are carried out to illustrate the effectiveness of MOEA/D-IWO. In addition, MOEA/D-IWO is compared with MOEA/D-DE, a new version of MOEA/D. The comparing results show the superiority of MOEA/D-IWO and indicate its potential for solving the antenna array synthesis problems.

  13. Switchable Phased Antenna Array with Passive Elements for 5G Mobile Terminals

    DEFF Research Database (Denmark)

    Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

    2017-01-01

    In this paper, a reconfigurable phased antenna array system is constructed for the mobile terminals in the context of 5G communication system. The proposed antenna system operates at the resonance frequency of 28 GHz. The reconfigurability of the antenna element is achieved by using a passive slot...

  14. Two dimensional thermo-optic beam steering using a silicon photonic optical phased array

    Science.gov (United States)

    Mahon, Rita; Preussner, Marcel W.; Rabinovich, William S.; Goetz, Peter G.; Kozak, Dmitry A.; Ferraro, Mike S.; Murphy, James L.

    2016-03-01

    Components for free space optical communication terminals such as lasers, amplifiers, and receivers have all seen substantial reduction in both size and power consumption over the past several decades. However, pointing systems, such as fast steering mirrors and gimbals, have remained large, slow and power-hungry. Optical phased arrays provide a possible solution for non-mechanical beam steering devices that can be compact and lower in power. Silicon photonics is a promising technology for phased arrays because it has the potential to scale to many elements and may be compatible with CMOS technology thereby enabling batch fabrication. For most free space optical communication applications, two-dimensional beam steering is needed. To date, silicon photonic phased arrays have achieved two-dimensional steering by combining thermo-optic steering, in-plane, with wavelength tuning by means of an output grating to give angular tuning, out-of-plane. While this architecture might work for certain static communication links, it would be difficult to implement for moving platforms. Other approaches have required N2 controls for an NxN element phased array, which leads to complexity. Hence, in this work we demonstrate steering using the thermo-optic effect for both dimensions with a simplified steering mechanism requiring only two control signals, one for each steering dimension.

  15. A transesophageal phased array transducer for ultrasonic imaging of the heart

    NARCIS (Netherlands)

    C.T. Lancée (Charles)

    1987-01-01

    textabstractIn this thesis the development of a miniaturized phased array ultrasound transducer is described. The application of this transducer in the field of echocardiology is devoted to transesophageal cross-sectional scanning of the heart and its great vessels. The enormous increase in diagnost

  16. Phased array ultrasonic technology contribution to engineering critical assessment (ECA) of economizer piping welds

    Energy Technology Data Exchange (ETDEWEB)

    Ciorau, P.; Gray, D.; Daks, W. [Ontario Power Generation, Pickering, Ontario (Canada)]. E-mail: peter.ciorau@opg.com

    2006-09-15

    This paper describes the application of phased array ultrasonic technology for engineering critical assessment of economizer piping welds. The objective is to detect and size fatigue cracks in the counter bore area of carbon steel boiler feedwater piping welds of a thermal station. A size accuracy of {+-} 1 mm for the outer ligament was required.

  17. A 28 GHz FR-4 Compatible Phased Array Antenna for 5G Mobile Phone Applications

    DEFF Research Database (Denmark)

    Ojaroudiparchin, Naser; Shen, Ming; Pedersen, Gert F.

    2015-01-01

    The design of a 28 GHz phased array antenna for future fifth generation (5G) mobile-phone applications has been presented in this paper. The proposed antenna can be implemented using low cost FR-4 substrates, while maintaining good performance in terms of gain and efficiency. This is achieved...

  18. A transesophageal phased array transducer for ultrasonic imaging of the heart

    NARCIS (Netherlands)

    C.T. Lancée (Charles)

    1987-01-01

    textabstractIn this thesis the development of a miniaturized phased array ultrasound transducer is described. The application of this transducer in the field of echocardiology is devoted to transesophageal cross-sectional scanning of the heart and its great vessels. The enormous increase in

  19. Integrated Automation of High-Throughput Screening and Reverse Phase Protein Array Sample Preparation

    DEFF Research Database (Denmark)

    Pedersen, Marlene Lemvig; Block, Ines; List, Markus

    multiplexing readouts, but this has a natural limitation. High-content screening via image acquisition and analysis allows multiplexing of few parameters, but is connected to substantial time consumption and complex logistics. We report on integration of Reverse Phase Protein Arrays (RPPA)-based readouts...

  20. First Results and Status of the PHARUS Phased Array Airborne SAR

    NARCIS (Netherlands)

    Greidanus, H.S.F.; Hoogeboom, P.; Koomen, P.J.; Snoeij, P.; Pouwels, H.

    1996-01-01

    PHARUS is an airborne fully polarimetric C band SAR. It uses a compact phased array antenna with electronic beam steering. Its design provides for a flexible and robust system concept, suited for operational use on small aircraft. PHARUS was developed in The Netherlands to cater for both the militar

  1. Angular-profile tuning of guided waves in hollow cylinders using a circumferential phased array.

    Science.gov (United States)

    Li, Jian; Rose, Joseph L

    2002-12-01

    Angular-profile tuning of guided waves in hollow cylinders is implemented by using partial loading of the elements in a circumferentially placed phased array. Each partial loading element generates nonaxisymmetric guided waves in a pipe. In earlier work, numerical calculations and experiments have shown that, for nonaxisymmetric guided waves, circumferential distribution of particle displacements (i.e., the angular profile) changes with propagation distance, frequency, and mode. To change the angular profile at a certain distance, either frequency or mode has to be changed for a single partial loading element. This is not the case, however, for a circumferential phased array. The total angular profile of a circumferential array is the superposition of contributions from all elements. If given the knowledge of the angular profile for a single element, the total guided wave angular profile can be controlled and thus focused at any specific circumferential location by a circumferentially placed phased array with adjustable voltage level and phase inputs. This angular profile tuning technique can be used for implementing a circumferential scan with focused, guided wave beams, which leads to the detection of smaller defects as a result of stronger focused beams. Algorithms and specific nondestructive evaluation (NDE) applications for pipe inspection using this technique are discussed.

  2. Switchable Phased Antenna Array with Passive Elements for 5G Mobile Terminals

    DEFF Research Database (Denmark)

    Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

    2017-01-01

    In this paper, a reconfigurable phased antenna array system is constructed for the mobile terminals in the context of 5G communication system. The proposed antenna system operates at the resonance frequency of 28 GHz. The reconfigurability of the antenna element is achieved by using a passive slo...

  3. Real-time B-scan ultrasonic imaging using a digital phased array system for NDE

    Science.gov (United States)

    Dunki-Jacobs, Robert; Thomas, Lewis

    A demonstration is presented of the ability to produce real-time images of metals on the basis of a phased-array ultrasound system. Attention is given to the critical role played by a beam-former. It is established that the present imaging system's resolution approaches the theoretical capabilities of the given aperture size and wavelength.

  4. Simulation of a ring resonator-based optical beamformer system for phased array receive antennas

    NARCIS (Netherlands)

    Tijmes, M.R.; Meijerink, Arjan; Roeloffzen, C.G.H.; Bentum, Marinus Jan

    2009-01-01

    A new simulator tool is described that can be used in the field of RF photonics. It has been developed on the basis of a broadband, continuously tunable optical beamformer system for phased array receive antennas. The application that is considered in this paper is airborne satellite reception of di

  5. Design of a ring resonator-based optical beam forming network for phased array receive antennas

    NARCIS (Netherlands)

    Klooster, van 't J.W.; Roeloffzen, C.G.H.; Meijerink, A.; Zhuang, L.; Marpaung, D.A.I.; Etten, van W.C.; Heideman, R.G.; Leinse, A.; Schippers, H.; Verpoorte, J.; Wintels, M.

    2008-01-01

    A novel squint-free ring resonator-based optical beam forming network (OBFN) for phased array antennas (PAA) is proposed. It is intended to provide broadband connectivity to airborne platforms via geostationary satellites. In this paper, we present the design of the OBFN and its control system. Our

  6. Development of an integrated photonic beamformer for electronically-steered Ku-band phased array antenna

    NARCIS (Netherlands)

    Zhuang, L.; Marpaung, D.A.I.; Burla, M.; Boot, R.; Hulzinga, A.; Beeker, W.P.; Beeker, Willem; van Dijk, P.; Roeloffzen, C.G.H.

    2011-01-01

    Currently an integrated photonic beamformer for electronically-steered Ku-band phased array antenna (PAA) system for satellite communications is being developed within a Dutch Point One R&D Innovation Project “Broadband Satellite Communication Services on High-Speed Transport Vehicles‿, targeting

  7. Development of a broadband integrated optical beamformer for Ku-Band Phased Array Antennas

    NARCIS (Netherlands)

    Roeloffzen, C.G.H.; van Dijk, Paul; Marpaung, D.A.I.; Burla, M.; Zhuang, L.

    2012-01-01

    Currently an integrated photonic beamformer for electronically-steered Ku-band phased array antenna (PAA) systems for satellite communications is being developed, targeting continuous reception of the full DVB-S band (10.7- 12.75 GHz), squint-free and seamless beam steering, and polarization

  8. Phased arrays of rectangular apertures on conformal cylindrical surfaces: A multimode equivalent network approach

    NARCIS (Netherlands)

    Gerini, G.; Zappelli, L.

    2004-01-01

    In this paper, we present an efficient integral equation formulation based on a multimode equivalent network (MEN) approach for the analysis of phased arrays on cylindrical surfaces using open-ended waveguide radiators. In addition to theory, experimental data are also presented showing very good ag

  9. Simulation of a ring-resonator based optical beamformer system for phased array receive antennas

    NARCIS (Netherlands)

    Tijmes, M.R.; Meijerink, A.; Bentum, M.J.; Roeloffzen, C.G.H.

    2009-01-01

    A new simulator tool is described that can be used in the field of RF photonics. It has been developed on the basis of a broadband, continuously tunable optical beamformer system for phased array receive antennas. The application that is considered in this paper is airborne satellite reception of di

  10. In-phase output beam from broad-area diode array using Talbot cavity

    Institute of Scientific and Technical Information of China (English)

    Pengfei Zhao; Qiang Li; Weirong Guo; Bo Liu; Tiechuan Zuo

    2007-01-01

    The robust phase locking of a linear diode array consisting of 49 broad-area emitters was demonstrated.The single lobe in the far field with output power of 0.83 W was observed. The far-field divergence was reduced to 2.0 mrad. The spectral bandwidth was reduced from 1.7 to 0.13 nm.

  11. Demonstration Results of the Triband, Multi-Beam Airborne Telemetry Phased Array (AirPA) System

    Science.gov (United States)

    2015-03-01

    Phased Array, antenna , digital beam-forming, beamforming, DBF, L-band, S-band, C-band, CTEIP, NAVAIR 16. SECURITY CLASSIFICATION OF...Outback BER After the flight test completed, the AirPA system was reconfigured to support the L-band flight test, Flight 171. At the request of the

  12. Improving the resolution of three-dimensional acoustic imaging with planar phased arrays

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Jacobsen, Finn; Fernandez Grande, Efren

    2012-01-01

    This paper examines and compares two methods of improving the quality of three-dimensional beamforming with phased microphone arrays. The intended application is the detection of aerodynamic noise sources on wind turbines. Both methods employ Fourier based deconvolution. The first method involves...

  13. Frequency Tunable Antennas and Novel Phased Array Feeding Networks for Next Generation Communication Systems

    Science.gov (United States)

    Avser, Bilgehan

    The thesis presents three dual-band frequency tunable antennas for carrier aggregation systems and two new feeding networks for reducing the number of phase shifters in limited-scan arrays. First, single- and dual-feed, dual-frequency, low-profile antennas with independent frequency tuning using varactor diodes are presented. The dual-feed planar inverted F-antenna (PIFA) has two operating frequencies which are independently tuned at 0.7--1.1 GHz and at 1.7--2.3 GHz with better than 10 dB impedance match. The isolation between the high-band and the low-band ports is > 13 dB; hence, one resonant frequency can be tuned without affecting the other. The single-feed contiguous-dual-band antenna has two resonant frequencies, which are independently tuned at 1.2--1.6 GHz at 1.6--2.3 GHz with better than 10 dB impedance match for most of the tuning range. And the single-feed dual-band antenna has two resonant frequencies, which are independently tuned at 0.7--1.0 GHz at 1.7--2.3 GHz with better than 10 dB impedance match for most of the tuning range. The tuning is done using varactor diodes with a capacitance range from 0.8 to 3.8 pF, which is compatible with RF MEMS devices. The antenna volumes are 63 x 100 x 3.15 mm3 on epsilon r = 3.55 substrates and the measured antenna efficiencies vary between 25% and 50% over the tuning range. The application areas are in carrier aggregation systems for fourth generation (4G) wireless systems. Next, a new phased array feeding network that employs random sequences of non-uniform sub-arrays (and a single phase shifter for each sub-array) is presented. When these sequences are optimized, the resulting phased arrays can scan over a wide region with low sidelobe levels. Equations for analyzing the random arrays and an algorithm for optimizing the array sequences are presented. Multiple random-solutions with different number of phase shifters and different set of sub-array groups are analyzed and design guidelines are presented. The

  14. MONOLITHIC ACTIVE PIXEL MATRIX WITH BINARY COUNTERS IN AN SOI PROCESS.

    Energy Technology Data Exchange (ETDEWEB)

    DUPTUCH,G.; YAREMA, R.

    2007-06-07

    The design of a Prototype monolithic active pixel matrix, designed in a 0.15 {micro}m CMOS SOI Process, is presented. The process allowed connection between the electronics and the silicon volume under the layer of buried oxide (BOX). The small size vias traversing through the BOX and implantation of small p-type islands in the n-type bulk result in a monolithic imager. During the acquisition time, all pixels register individual radiation events incrementing the counters. The counting rate is up to 1 MHz per pixel. The contents of counters are shifted out during the readout phase. The designed prototype is an array of 64 x 64 pixels and the pixel size is 26 x 26 {micro}m{sup 2}.

  15. Performance Investigation of a Mobile Terminal Phased Array With User Effects at 3.5 GHz for LTE Advanced

    DEFF Research Database (Denmark)

    Syrytsin, Igor; Zhang, Shuai; Pedersen, Gert F.

    2016-01-01

    This paper discusses the performance investigation of a beam-steerable antenna system at 3.5 GHz with user effects. To show how to investigate the performance of such a system, an antenna array system in a metal frame structure is used as one example. The antenna system includes four sub phased...... arrays. Each sub array consists of two slot antenna elements. In the application, it is possible to control the beam by phase in each sub array and switch the beam among four phased arrays, depending on the incoming power and interference directions. The main idea in this paper is to evaluate...... the performance of the phased array system by using the metrics of total scan pattern and coverage efficiency with CTIA standards. The proposed antenna system is simulated and measured in free space and with user effects. Losses in both scan angles and coverage efficiency due to the user effects are also given...

  16. The OSU self-phased array for propagation measurements using the 11.7 GHz CTS beacon

    Science.gov (United States)

    Theobold, D. M.; Hodge, D. B.

    1976-01-01

    A self phased array was developed for propagation measurements on an earth-space path. The 11.7 GHz CTS beacon was used as the signal source. The self phased array was used to measure angle of arrival as well as attenuation and scintillation statistics. The performance of the array is described, and sample data are presented. The tracking capability of the self phased array was also studied. This technique permits fully electronic, nonmechanical satellite tracking, thus simplifying unmanned operation and eliminating severe weather tracking constraints.

  17. Phased annular array transducers for omnidirectional guided wave mode control in isotropic plate like structures

    Science.gov (United States)

    Koduru, Jaya P.; Momeni, Sepandarmaz; Rose, Joseph L.

    2013-12-01

    Ultrasonic guided waves are fast emerging as a reliable tool for continuous structural health monitoring. Their multi-modal nature along with their long range propagation characteristics offer several possibilities for interrogating structures. Transducers commonly used to generate guided waves in structures excite multiple modes at any frequency; their complex scattering and reflection from defects and boundaries often complicates the extraction of useful information. Often it is desirable to control the guided wave modes propagating in a structure to take advantage of their unique properties for different applications. Earlier attempts at guided wave mode control involved developing fixed wavelength linear and annular array transducers. Their only disadvantage is that the transducer is limited to a particular wavelength and a change in wavelength necessitates a change in the transducer. In this paper, we propose the development of an annular array transducer that can generate mode controlled omnidirectional guided waves by independently controlling the amplitude and phase of the array elements. A simplified actuator model that approximates the transducer loading on the structure to a constant pressure load under the array elements is assumed and an optimization problem is set up to compute the excitation voltage and phase of the elements. A five element annular array transducer is designed utilizing 1-3 type piezocomposite materials. The theoretical computations are experimentally verified on an aluminum plate like structure by exciting A0 and S0 guided wave modes.

  18. Evaluation of Methods for In-Situ Calibration of Field-Deployable Microphone Phased Arrays

    Science.gov (United States)

    Humphreys, William M.; Lockard, David P.; Khorrami, Mehdi R.; Culliton, William G.; McSwain, Robert G.

    2017-01-01

    Current field-deployable microphone phased arrays for aeroacoustic flight testing require the placement of hundreds of individual sensors over a large area. Depending on the duration of the test campaign, the microphones may be required to stay deployed at the testing site for weeks or even months. This presents a challenge in regards to tracking the response (i.e., sensitivity) of the individual sensors as a function of time in order to evaluate the health of the array. To address this challenge, two different methods for in-situ tracking of microphone responses are described. The first relies on the use of an aerial sound source attached as a payload on a hovering small Unmanned Aerial System (sUAS) vehicle. The second relies on the use of individually excited ground-based sound sources strategically placed throughout the array pattern. Testing of the two methods was performed in microphone array deployments conducted at Fort A.P. Hill in 2015 and at Edwards Air Force Base in 2016. The results indicate that the drift in individual sensor responses can be tracked reasonably well using both methods. Thus, in-situ response tracking methods are useful as a diagnostic tool for monitoring the health of a phased array during long duration deployments.

  19. Graphene quantum dots modified silicon nanowire array for ultrasensitive detection in the gas phase

    Science.gov (United States)

    Li, T. Y.; Duan, C. Y.; Zhu, Y. X.; Chen, Y. F.; Wang, Y.

    2017-03-01

    Si nanostructure-based gas detectors have attracted much attention due to their huge surface areas, relatively high carrier mobility, maneuverability for surface functionalization and compatibility to modern electronic industry. However, the unstable surface of Si, especially for the nanostructures in a corrosive atmosphere, hinders their sensitivity and reproducibility when used for detection in the gas phase. In this study, we proposed a novel strategy to fabricate a Si-based gas detector by using the vertically aligned Si nanowire (SiNW) array as a skeleton and platform, and decorated chemically inert graphene quantum dots (GQDs) to protect the SiNWs from oxidation and promote the carriers’ interaction with the analytes. The radial core–shell structures of the GQDs/SiNW array were then assembled into a resistor-based gas detection system and evaluated by using nitrogen dioxide (NO2) as the model analyte. Compared to the bare SiNW array, our novel sensor exhibited ultrahigh sensitivity for detecting trace amounts of NO2 with the concentration as low as 10 ppm in room temperature and an immensely reduced recovery time, which is of significant importance for their practical application. Meanwhile, strikingly, reproducibility and stability could also be achieved by showing no sensitivity decline after storing the GQDs/SiNW array in air for two weeks. Our results demonstrate that protecting the surface of the SiNW array with chemically inert GQDs is a feasible strategy to realize ultrasensitive detection in the gas phase.

  20. Phase-locked arrays of vertical-cavity surface-emitting lasers

    Energy Technology Data Exchange (ETDEWEB)

    Warren, M.E.; Hadley, G.R.; Lear, K.L.; Gourley, P.L.; Vawter, G.A.; Zolper, J.C.; Brennan, T.M.; Hammons, B.E.

    1994-05-01

    Vertical Cavity Surface-Emitting Lasers (VCSELs) are of increasing interest to the photonics community because of their surface-emitting structure, simple fabrication and packaging, wafer-level testability and potential for low cost. Scaling VCSELs to higher power outputs requires increasing the device area, which leads to transverse mode control difficulties if devices become larger than 10-15 microns. One approach to increasing the device size while maintaining a well controlled transverse mode profile is to form coupled or phase-locked, two-dimensional arrays of VCSELs that are individually single-transverse mode. The authors have fabricated and characterized both photopumped and electrically injected two-dimensional VCSEL arrays with apertures over 100 microns wide. Their work has led to an increased understanding of these devices and they have developed new types of devices, including hybrid semiconductor/dielectric mirror VCSEL arrays, VCSEL arrays with etched trench, self-aligned, gold grid contacts and arrays with integrated phase-shifters to correct the far-field pattern.

  1. Monolithically integrated multi-wavelength MQW-DBR laser diodes fabricated by selective metalorganic vapor phase epitaxy

    Science.gov (United States)

    Sasaki, Tatsuya; Yamaguchi, Masayuki; Kitamura, Mitsuhiro

    1994-12-01

    Selective metalorganic vapor phase epitaxy (MOVPE) was used to grow InGaAsP/InP layers for fabricating multi-wavelength laser diodes. Multiple quantum well (MQW) active and passive waveguides were simultaneously grown by one step selective growth. The selectively grown layer thickness increases with the mask stripe width. This growth enhancement can be used to control the lasing wavelength of distributed Bragg reflector (DBR) laser diodes, because the effective refractive index of the MQW passive waveguide at the DBR region can be controlled by the mask stripe width. This simple technique was used to fabricate multi-wavelength MQW-DBR laser diodes. In the selective growth, the MQW structure was grown under 150 Torr to obtain large bandgap energy shift for the MQW passive waveguides compared to the active waveguide, which was effective for wide wavelength tuning range. On the contrary, a bulk InGaAsP guide layer was grown under 35 Torr to prevent too much composition shift and maintain high crystalline quality of the MQW passive waveguide. For 10 consecutive laser diodes, a wavelength span of over 20 nm with accurate wavelength control was achieved.

  2. Inspection design using 2D phased array, TFM and cueMAP software

    Energy Technology Data Exchange (ETDEWEB)

    McGilp, Ailidh; Dziewierz, Jerzy; Lardner, Tim; Mackersie, John; Gachagan, Anthony [Centre for Ultrasonic Engineering, University of Strathclyde, Glasgow (United Kingdom)

    2014-02-18

    A simulation suite, cueMAP, has been developed to facilitate the design of inspection processes and sparse 2D array configurations. At the core of cueMAP is a Total Focusing Method (TFM) imaging algorithm that enables computer assisted design of ultrasonic inspection scenarios, including the design of bespoke array configurations to match the inspection criteria. This in-house developed TFM code allows for interactive evaluation of image quality indicators of ultrasonic imaging performance when utilizing a 2D phased array working in FMC/TFM mode. The cueMAP software uses a series of TFM images to build a map of resolution, contrast and sensitivity of imaging performance of a simulated reflector, swept across the inspection volume. The software takes into account probe properties, wedge or water standoff, and effects of specimen curvature. In the validation process of this new software package, two 2D arrays have been evaluated on 304n stainless steel samples, typical of the primary circuit in nuclear plants. Thick section samples have been inspected using a 1MHz 2D matrix array. Due to the processing efficiency of the software, the data collected from these array configurations has been used to investigate the influence sub-aperture operation on inspection performance.

  3. Finite Element Analysis of Ultrasonic Phased Array Inspections on Anisotropic Welds

    Science.gov (United States)

    Harvey, G.; Tweedie, A.; Carpentier, C.; Reynolds, P.

    2011-06-01

    This paper describes a theoretical investigation into the behaviour of anisotropic welds under phased array inspection procedures using a 128 element linear array. Two advanced inspection techniques are simulated, and their suitability compared. A finite element (FE) model, configured in PZFlex, is used to represent both the variations in crystal orientation found in a typical anisotropic weld, and also the linear array configuration. Firstly, through transmission spectra of the weld are used to determine the optimum operating frequency and configuration of the array in order to detect a 3 mm SDH in the weld. Next, the Full Matrix Capture (FMC) technique is simulated, and an image of the weld constructed using the Total Focussing Method (TFM). This is accomplished by transmitting on each element sequentially, while receiving on the remaining 127 elements. This approach provides spatial averaging over the weld area, reducing the distortion caused by the anisotropic media. Finally, Time Reversal Acoustic (TRA) methods were employed to coherently focus the array at the defect and compensate for the elemental timing variations caused by the complex medium. Results illustrate the potential for inspecting anisotropic welds when using correctly designed arrays and implementing novel inspection procedures.

  4. Inspection design using 2D phased array, TFM and cueMAP software

    Science.gov (United States)

    McGilp, Ailidh; Dziewierz, Jerzy; Lardner, Tim; Mackersie, John; Gachagan, Anthony

    2014-02-01

    A simulation suite, cueMAP, has been developed to facilitate the design of inspection processes and sparse 2D array configurations. At the core of cueMAP is a Total Focusing Method (TFM) imaging algorithm that enables computer assisted design of ultrasonic inspection scenarios, including the design of bespoke array configurations to match the inspection criteria. This in-house developed TFM code allows for interactive evaluation of image quality indicators of ultrasonic imaging performance when utilizing a 2D phased array working in FMC/TFM mode. The cueMAP software uses a series of TFM images to build a map of resolution, contrast and sensitivity of imaging performance of a simulated reflector, swept across the inspection volume. The software takes into account probe properties, wedge or water standoff, and effects of specimen curvature. In the validation process of this new software package, two 2D arrays have been evaluated on 304n stainless steel samples, typical of the primary circuit in nuclear plants. Thick section samples have been inspected using a 1MHz 2D matrix array. Due to the processing efficiency of the software, the data collected from these array configurations has been used to investigate the influence sub-aperture operation on inspection performance.

  5. Reconfigurable Transmission Line for a Series-Fed Ku-Band Phased Array Using a Single Feed

    Science.gov (United States)

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

    2013-01-01

    The paper presents a novel approach to realize a lowcost phased array using a simple feeding mechanism. Specifically, a single coplanar stripline (CPS) transmission line is used to feed the antenna array elements. By controlling the CPS's dielectric properties using a movable dielectric plunger, scanning is achieved. Due to its simplicity, single feed, and no phase shifters, this approach leads to a dramatic reduction in cost which does not scale for larger arrays.

  6. GPS-Like Phasing Control of the Space Solar Power System Transmission Array

    Science.gov (United States)

    Psiaki, Mark L.

    2003-01-01

    The problem of phasing of the Space Solar Power System's transmission array has been addressed by developing a GPS-like radio navigation system. The goal of this system is to provide power transmission phasing control for each node of the array that causes the power signals to add constructively at the ground reception station. The phasing control system operates in a distributed manner, which makes it practical to implement. A leader node and two radio navigation beacons are used to control the power transmission phasing of multiple follower nodes. The necessary one-way communications to the follower nodes are implemented using the RF beacon signals. The phasing control system uses differential carrier phase relative navigation/timing techniques. A special feature of the system is an integer ambiguity resolution procedure that periodically resolves carrier phase cycle count ambiguities via encoding of pseudo-random number codes on the power transmission signals. The system is capable of achieving phasing accuracies on the order of 3 mm down to 0.4 mm depending on whether the radio navigation beacons operate in the L or C bands.

  7. Phase-noise-induced resonance in arrays of coupled excitable neural models.

    Science.gov (United States)

    Xiaoming Liang; Liang Zhao

    2013-08-01

    Recently, it is observed that, in a single neural model, phase noise (time-varying signal phase) arising from an external stimulating signal can induce regular spiking activities even if the signal is subthreshold. In addition, it is also uncovered that there exists an optimal phase noise intensity at which the spiking rhythm coincides with the frequency of the subthreshold signal, resulting in a phase-noise-induced resonance phenomenon. However, neurons usually do not work alone, but are connected in the form of arrays or blocks. Therefore, we study the spiking activity induced by phase noise in arrays of globally and locally coupled excitable neural models. We find that there also exists an optimal phase noise intensity for generating large neural response and such an optimal value is significantly decreased compared to an isolated single neuron case, which means the detectability in response to the subthreshold signal of neurons is sharply improved because of the coupling. In addition, we reveal two new resonance behaviors in the neuron ensemble with the presence of phase noise: there exist optimal values of both coupling strength and system size, where the coupled neurons generate regular spikes under subthreshold stimulations, which are called as coupling strength and system size resonance, respectively. Finally, the dependence of phase-noise-induced resonance on signal frequency is also examined.

  8. Design and Implementation of a Beam Forming Network for a Phased Array Antenna

    Directory of Open Access Journals (Sweden)

    S. Devimeena

    2015-03-01

    Full Text Available This dissertation presents a beam forming network (BFN for phased array antenna-based on coherently radiating periodic structure (CORPS. The elements of CORPS are selected in such a way to obtain broad band characteristics, good return loss and good isolation between the radiating elements. These elements were arranged in such a way that the BFN naturally produces Gaussian amplitude. This methodology reduces the complexity of the conventional phased array design making it more flexible and minimizing the loss of energy inside the structure. A phase shifter design is proposed for the CORPS. The entire BFN’s sub-blocks have been designed for the frequency band of 5.925 GHz to 6.425 GHz, which find applications in communication satellite, fixed wireless systems.Defence Science Journal, Vol. 65, No. 1, January 2015, pp.46-52, DOI:http://dx.doi.org/10.14429/dsj.65.6940

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

    Science.gov (United States)

    1978-01-01

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

  10. Ultrasound array transmitter architecture with high timing resolution using embedded phase-locked loops.

    Science.gov (United States)

    Smith, Peter R; Cowell, David M J; Raiton, Benjamin; Ky, Chau Vo; Freear, Steven

    2012-01-01

    Coarse time quantization of delay profiles within ultrasound array systems can produce undesirable side lobes in the radiated beam profile. The severity of these side lobes is dependent upon the magnitude of phase quantization error--the deviation from ideal delay profiles to the achievable quantized case. This paper describes a method to improve interchannel delay accuracy without increasing system clock frequency by utilizing embedded phase-locked loop (PLL) components within commercial field-programmable gate arrays (FPGAs). Precise delays are achieved by shifting the relative phases of embedded PLL output clocks in 208-ps steps. The described architecture can achieve the necessary interelement timing resolution required for driving ultrasound arrays up to 50 MHz. The applicability of the proposed method at higher frequencies is demonstrated by extrapolating experimental results obtained using a 5-MHz array transducer. Results indicate an increase in transmit dynamic range (TDR) when using accurate delay profiles generated by the embedded-PLL method described, as opposed to using delay profiles quantized to the system clock.

  11. Simulation and Application of Dynamic Inspection Modes Using Ultrasonic Phased Arrays

    Science.gov (United States)

    Mahaut, Steve; Chatillon, Sylvain; Raillon-Picot, Raphaële; Calmon, Pierre

    2004-02-01

    NDT techniques using phased arrays are more and more applied in different industrial contexts. Their main advantage is the adaptability to the testing configuration : ability to steer and to focus the beam inside the inspected component taking account the geometry and the constitutive materials, high acquisition rates without raster scanning pattern of the probe using electronic commutation, sectorial scanning inspection to fully insonify the specimen, etc. Optimal use of phased arrays requires simulation tools accounting for the actual testing configuration. For several years, such tools have been developed at the French Atomic Energy Commission. Delay laws, beam forming and echo formation (interaction of the beam with defects or specimen boundaries) models are used to design the arrays, to conceive and to evaluate the performances of methods in realistic and complex configurations. Recently, works have been made to extend the simulation skills to advanced inspection modes : electronic commutation with separate Transmission/Reception patterns, non-symmetric Transmit/Receive delay laws, sectorial scanning inspections. This paper presents some examples of simulation and application of such inspections carried out over complex specimen. These examples demonstrate the interest for simulation tools in terms of prediction, optimization and interpretation of phased arrays techniques.

  12. Flexible, phase-matched, linear receive arrays for high-field MRI in monkeys.

    Science.gov (United States)

    Goense, Jozien; Logothetis, Nikos K; Merkle, Hellmut

    2010-10-01

    High signal-to-noise ratios (SNR) are essential for high-resolution anatomical and functional MRI. Phased arrays are advantageous for this but have the drawback that they often have inflexible and bulky configurations. Particularly in experiments where functional MRI is combined with simultaneous electrophysiology, space constraints can be prohibitive. To this end we developed a highly flexible multiple receive element phased array for use on anesthetized monkeys. The elements are interchangeable and different sizes and combinations of coil elements can be used, for instance, combinations of single and overlapped elements. The preamplifiers including control electronics are detachable and can serve a variety of prefabricated and phase matched arrays of different configurations, allowing the elements to always be placed in close proximity to the area of interest. Optimizing performance of the individual elements ensured high SNR at the cortical surface as well as in deeper laying structures. Performance of a variety of arrangements of gapped linear arrays was evaluated at 4.7 and 7T in high-resolution anatomical and functional MRI.

  13. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

    Science.gov (United States)

    Hynynen, Kullervo; Jones, Ryan M.

    2016-09-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

  14. Carbon Fiber Composite Monoliths as Catalyst Supports

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Pickel, Joseph M [ORNL; Blom, Douglas Allen [ORNL; Burchell, Timothy D [ORNL

    2006-01-01

    Carbon fiber composite monoliths are rigid bodies that can be activated to a large surface area, have tunable porosity, and proven performance in gas separation and storage. They are ideal as catalyst supports in applications where a rigid support, with open structure and easy fluid access is desired. We developed a procedure for depositing a dispersed nanoparticulate phase of molybdenum carbide (Mo2C) on carbon composite monoliths in the concentration range of 3 to 15 wt% Mo. The composition and morphology of this phase was characterized using X-ray diffraction and electron microscopy, and a mechanism was suggested for its formation. Molybdenum carbide is known for its catalytic properties that resemble those of platinum group metals, but at a lower cost. The materials obtained are expected to demonstrate catalytic activity in a series of hydrocarbon reactions involving hydrogen transfer. This project demonstrates the potential of carbon fiber composite monoliths as catalyst supports.

  15. Carbon Fiber Composite Monoliths for Catalyst Supports

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL; Pickel, Joseph M [ORNL; Blom, Douglas Allen [ORNL; Burchell, Timothy D [ORNL

    2006-01-01

    Carbon fiber composite monoliths are rigid bodies that can be activated to a large surface area, have tunable porosity, and proven performance in gas separation and storage. They are ideal as catalyst supports in applications where a rigid support, with open structure and easy fluid access is desired. We developed a procedure for depositing a dispersed nanoparticulate phase of molybdenum carbide (Mo2C) on carbon composite monoliths in the concentration range of 3 to 15 wt% Mo. The composition and morphology of this phase was characterized using X-ray diffraction and electron microscopy, and a mechanism was suggested for its formation. Molybdenum carbide is known for its catalytic properties that resemble those of platinum group metals, but at a lower cost. The materials obtained are expected to demonstrate catalytic activity in a series of hydrocarbon reactions involving hydrogen transfer. This project demonstrates the potential of carbon fiber composite monoliths as catalyst supports.

  16. Measured Sensitivity of the First Mark II Phased Array Feed on an ASKAP Antenna

    CERN Document Server

    Chippendale, A P; Beresford, R J; Hampson, G A; Macleod, A; Shaw, R D; Brothers, M L; Cantrall, C; Forsyth, A R; Hay, S G; Leach, M

    2015-01-01

    This paper presents the measured sensitivity of CSIRO's first Mk. II phased array feed (PAF) on an ASKAP antenna. The Mk. II achieves a minimum system-temperature-over-efficiency $T_\\mathrm{sys}/\\eta$ of 78 K at 1.23 GHz and is 95 K or better from 835 MHz to 1.8 GHz. This PAF was designed for the Australian SKA Pathfinder telescope to demonstrate fast astronomical surveys with a wide field of view for the Square Kilometre Array (SKA).

  17. Facet Reflection Coefficient of Phase-locked Diode Laser Array in an External Cavity

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A diode laser array(DLA)positioned in an external cavity can receive the radiations emitted from its neighboring elements (C1) and that of itself (S) after being reflected at the DLA facet as well as from the external mirror (C0). Considering the fact that|C0/S| should be larger than unity if the external cavity is effective,and|C1/S| should be larger than unity if the phase locking may be established in the external cavity.The requirements on the reflection at the facet of the diode laser array have been specified in terms of the cavity length and reflection coefficient of the external mirror.

  18. Universal gates based on targeted phase shifts in a 3D neutral atom array

    Science.gov (United States)

    Kumar, Aishwarya; Wang, Yang; Wu, Tsung-Yao; Weiss, David

    2016-05-01

    We demonstrate a new approach to making targeted single qubit gates using Cesium atoms in a 5x5x5 3D neutral atom array. It combines targeted AC Zeeman phase shifts with global microwave pulses to produce arbitrary single qubit gates. Non-targeted atoms are left virtually untouched by the gates. We have addressed 48 sites, targeted individually, in a 40% full array. We have also performed Randomized Benchmarking to characterize the fidelity and crosstalk errors of this gate. These gates are highly insensitive to addressing beam imperfections and can be applied to other systems and geometries. Supported by NSF.

  19. Flat-Top Sector Beams Using Only Array Element Phase Weighting: A Metaheuristic Optimization Approach

    Science.gov (United States)

    2012-10-10

    Technique,” Microwave and Optical Technology Letters 23(4), 224–226 (November 1999). 11. W.T. Li and X.W. Shi, “An Improved Particle Swarm...Unequally Spaced Linear Antenna Arrays Using a Modified Tabu Search Algorithm,” Microwave and Optical Technology Letters 36(1), 16–20 (2003...DeFord, J.F., and O.P. Gandhi , “Phase-Only Synthesis of Minimum Peak Sidelobe Patterns for Linear and Planar Arrays,” IEEE Trans. Antennas Propag. 36(2

  20. A 19 element cryogenic phased array feed for the Green Bank Telescope

    Science.gov (United States)

    Roshi, D. Anish; Warnick, Karl F.; Brandt, Joe; Fisher, J. Richard; Ford, Pam; Jeffs, Brian D.; Marganian, Paul; McLeod, Morgan; Mello, Melinda; Morgan, Matthew; Norrod, Roger; Shillue, William; Simon, Robert; White, Steven

    2015-10-01

    A low-noise cryogenic phased array feed (PAF) is in development for the Green Bank Telescope (GBT). The feed consists of electrically small elements tuned to operate near 1.4 GHz and optimized for active impedance matching to cooled front end low noise amplifiers (LNAs). A prototype cryogenic PAF with analog fiber link, down-converters and streaming data acquisition system was recently tested on the GBT. Preliminary results are presented. These efforts form an important step towards the development of a new receiver system, the focal L-band array for the GBT (FLAG).