WorldWideScience

Sample records for thick frequency selective

  1. Wide-range frequency selectivity in an acoustic sensor fabricated using a microbeam array with non-uniform thickness

    International Nuclear Information System (INIS)

    Shintaku, Hirofumi; Kotera, Hidetoshi; Kobayashi, Takayuki; Zusho, Kazuki; Kawano, Satoyuki

    2013-01-01

    In this study, we have demonstrated the fabrication of a microbeam array (MBA) with various thicknesses and investigated the suitability it for an acoustic sensor with wide-range frequency selectivity. For this, an MBA composed of 64 beams, with thicknesses varying from 2.99–142 µm, was fabricated by using single gray-scale lithography and a thick negative photoresist. The vibration of the beams in air was measured using a laser Doppler vibrometer; the resonant frequencies of the beams were measured to be from 11.5 to 290 kHz. Lastly, the frequency range of the MBA with non-uniform thickness was 10.9 times that of the MBA with uniform thickness. (paper)

  2. Frequency selective bolometers

    DEFF Research Database (Denmark)

    Kowitt, M.S.; Fixsen, D.J.; Goldin, A.

    1996-01-01

    We propose a concept for radiometry in the millimeter, the submillimeter, and the far-IR spectral regions, the frequency selective bolometer (FSB). This system uses a bolometer as a coupled element of a tuned quasi-optical interference filter in which the absorption, the transmission......-dimensional transmission-line model. Instruments based on FSB technology should have several advantages over current multiband bolometric radiometers including smaller and more compact cryogenic optics; reduced demands on cryostat size and weight, high coupling efficiency, minimum constraints on the geometry in the focal...

  3. Frequency selectivity at very low centre frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Marquardt, Torsten

    2010-01-01

    measurements based on OAE suppression techniques and notched-noise masking data psychophysically measured for centre frequencies in the range 50-125 Hz, this study examines how individual differences in frequency selectivity, as well as in masking, may occur at very low CFs due to individual differences...

  4. Binaural frequency selectivity in humans.

    Science.gov (United States)

    Verhey, Jesko L; van de Par, Steven

    2018-01-23

    Several behavioural studies in humans have shown that listening to sounds with two ears that is binaural hearing, provides the human auditory system with extra information on the sound source that is not available when sounds are only perceived through one ear that is monaurally. Binaural processing involves the analysis of phase and level differences between the two ear signals. As monaural cochlea processing (in each ear) precedes the neural stages responsible for binaural processing properties it is reasonable to assume that properties of the cochlea may also be observed in binaural processing. A main characteristic of cochlea processing is its frequency selectivity. In psychoacoustics, there is an ongoing discussion on the frequency selectivity of the binaural auditory system. While some psychoacoustic experiments seem to indicate poorer frequency selectivity of the binaural system than that of the monaural processing others seem to indicate the same frequency selectivity for monaural and binaural processing. This study provides an overview of these seemingly controversial results and the different explanations that were provided to account for the different results. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  5. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dewani, Aliya A., E-mail: a.ashraf@griffith.edu.au; O’Keefe, Steven G.; Thiel, David V.; Galehdar, Amir [School Of Electrical Engineering, Griffith University, Brisbane, 4111 (Australia)

    2015-02-15

    A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  6. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Science.gov (United States)

    Dewani, Aliya A.; O'Keefe, Steven G.; Thiel, David V.; Galehdar, Amir

    2015-02-01

    A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  7. Femtosecond frequency mixing in optically thick bulk GaAs

    International Nuclear Information System (INIS)

    Jho, Young Dahl; Kim, Dai Sik

    1999-01-01

    Femtosecond degenerate four-wave mixing experiment (FWM) has been performed at 11 K in transmission geometry. Strong signal where the energy extends well above the bandedge is still observed in FWM transmittance although the thickness is larger than the penetration depth by an order. In addition, these above-the-bandgap signals are mostly confined to the negative time delay region and shift further into the negative time as the detection energy increases. All these unusual phenomena can be understood by the third order frequency mixing (2ω 2 -ω 1 ; ω 2 > ω 1 )

  8. Relationship between soft stratum thickness and predominant frequency of ground based on microtremor observation data

    Science.gov (United States)

    Chia, Kenny; Lau, Tze Liang

    2017-07-01

    Despite categorized as low seismicity group, until being affected by distant earthquake ground motion from Sumatra and the recent 2015 Sabah Earthquake, Malaysia has come to realize that seismic hazard in the country is real and has the potential to threaten the public safety and welfare. The major concern in this paper is to study the effect of local site condition, where it could amplify the magnitude of ground vibration at sites. The aim for this study is to correlate the thickness of soft stratum with the predominant frequency of soil. Single point microtremor measurements were carried out at 24 selected points where the site investigation reports are available. Predominant period and frequency at each site are determined by Nakamura's method. The predominant period varies from 0.22 s to 0.98 s. Generally, the predominant period increases when getting closer to the shoreline which has thicker sediments. As far as the thickness of the soft stratum could influence the amplification of seismic wave, the advancement of micotremor observation to predict the thickness of soft stratum (h) from predominant frequency (fr) is of the concern. Thus an empirical relationship h =54.917 fr-1.314 is developed based on the microtremor observation data. The empirical relationship will be benefited in the prediction of thickness of soft stratum based on microtremor observation for seismic design with minimal cost compared to conventional boring method.

  9. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Directory of Open Access Journals (Sweden)

    Aliya A. Dewani

    2015-02-01

    Full Text Available A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm, flexible transparent plastic substrate (relative permittivity 3.2. It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  10. Filter and slice thickness selection in SPECT image reconstruction

    International Nuclear Information System (INIS)

    Ivanovic, M.; Weber, D.A.; Wilson, G.A.; O'Mara, R.E.

    1985-01-01

    The choice of filter and slice thickness in SPECT image reconstruction as function of activity and linear and angular sampling were investigated in phantom and patient imaging studies. Reconstructed transverse and longitudinal spatial resolution of the system were measured using a line source in a water filled phantom. Phantom studies included measurements of the Data Spectrum phantom; clinical studies included tomographic procedures in 40 patients undergoing imaging of the temporomandibular joint. Slices of the phantom and patient images were evaluated for spatial of the phantom and patient images were evaluated for spatial resolution, noise, and image quality. Major findings include; spatial resolution and image quality improve with increasing linear sampling frequencies over the range of 4-8 mm/p in the phantom images, best spatial resolution and image quality in clinical images were observed at a linear sampling frequency of 6mm/p, Shepp and Logan filter gives the best spatial resolution for phantom studies at the lowest linear sampling frequency; smoothed Shepp and Logan filter provides best quality images without loss of resolution at higher frequencies and, spatial resolution and image quality improve with increased angular sampling frequency in the phantom at 40 c/p but appear to be independent of angular sampling frequency at 400 c/p

  11. Resonant frequency function of thickness-shear vibrations of rectangular crystal plates.

    Science.gov (United States)

    Wang, Ji; Yang, Lijun; Pan, Qiaoqiao; Chao, Min-Chiang; Du, Jianke

    2011-05-01

    The resonant frequencies of thickness-shear vibrations of quartz crystal plates in rectangular and circular shapes are always required in the design and manufacturing of quartz crystal resonators. As the size of quartz crystal resonators shrinks, for rectangular plates we must consider effects of both length and width for the precise calculation of resonant frequency. Starting from the three-dimensional equations of wave propagation in finite crystal plates and the general expression of vibration modes, we obtained the relations between frequency and wavenumbers. By satisfying the major boundary conditions of the dominant thickness-shear mode, three wavenumber solutions are obtained and the frequency equation is constructed. It is shown the resonant frequency of thickness-shear mode is a second-order polynomial of aspect ratios. This conforms to known results in the simplest form and is applicable to further analytical and experimental studies of the frequency equation of quartz crystal resonators.

  12. Thickness Measurement of a Film on a Substrate by Low-Frequency Ultrasound

    Institute of Scientific and Technical Information of China (English)

    LI Ming-Xuan; WANG Xiao-Min; MAO Jie

    2004-01-01

    @@ We describe a new simple technique for the low-frequency ultrasonic thickness measurement of an air-backed soft thin layer attached on a hard substrate of finite thickness through the frequency-shifts of the substrate resonances by the substrate-side insonification. A plane compressive wave impinging normally on the substrate surface from a liquid is studied. Low frequency here means an interrogating acoustical wave frequency of less than half of coating to the substrate. Equations for the frequency-shifts are derived and solved by the Newton iterative method and the Taylor expansion method, respectively, indicating satisfactory agreement within the range of interest of thickness ratio of the thin layer to the substrate for a polymer-aluminium structure. An experimental setup is constructed to verify the validity of the technique.

  13. Frequency Invariability of (Pb,La)(Zr,Ti)O₃ Antiferroelectric Thick-Film Micro-Cantilevers.

    Science.gov (United States)

    An, Kun; Jin, Xuechen; Meng, Jiang; Li, Xiao; Ren, Yifeng

    2018-05-13

    Micro-electromechanical systems comprising antiferroelectric layers can offer both actuation and transduction to integrated technologies. Micro-cantilevers based on the (Pb 0.97 La 0.02 )(Zr 0.95 Ti 0.05 )O₃ (PLZT) antiferroelectric thick film are fabricated by the micro-nano manufacturing process, to utilize the effect of phase transition induced strain and sharp phase switch of antiferroelectric materials. When micro-cantilevers made of antiferroelectric thick films were driven by sweep voltages, there were two resonant peaks corresponding to the natural frequency shift from 27.8 to 27.0 kHz, before and after phase transition. This is the compensation principle for the PLZT micro-cantilever to tune the natural frequency by the amplitude modulation of driving voltage, rather than of frequency modulation. Considering the natural frequency shift about 0.8 kHz and the frequency tuning ability about 156 Hz/V before the phase transition, this can compensate the frequency shift caused by increasing temperature by tuning only the amplitude of driving voltage, when the ultrasonic micro-transducer made of antiferroelectric thick films works for such a long period. Therefore, antiferroelectric thick films with hetero-structures incorporated into PLZT micro-cantilevers not only require a lower driving voltage (no more than 40 V) than rival bulk piezoelectric ceramics, but also exhibit better performance of frequency invariability, based on the amplitude modulation.

  14. Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

    Science.gov (United States)

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

    2010-10-01

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

  15. Frequency characteristics of the MIM thick film capacitors fabricated by laser micro-cladding electronic pastes

    International Nuclear Information System (INIS)

    Cao Yu; Li Xiangyou; Zeng Xiaoyan

    2008-01-01

    With rapid development of the electronic industry, how to respond the market requests quickly, shorten R and D prototyping fabrication period, and reduce the cost of the electronic devices have become a challenge work, which need flexible manufacturing methods. In this work, two direct write processing methods, direct material deposition by microPen and Nd:YAG laser micro-cladding, are integrated with CAD/CAM technology for the hybrid fabrication of passive electronic components. Especially, the metal-insulator-metal (MIM) type thick film capacitors are fabricated on ceramic substrates by this method. A basic two-step procedure of laser micro-cladding electronic pastes (LMCEPs) process for the thick film pattern preparation is presented. For a better understanding of the MIM thick film capacitor characterization, equivalent circuit models at low-frequency and high-frequency domains are introduced, respectively. The frequency characteristics tests up to 1.8 GHz of capacitance stability, equivalent series resistance (ESR), equivalent series inductance (ESL) and impendence are performed, and the results show good DC voltage stability (<2.48%), good frequency stability (<2.6%) and low dissipation factor (<0.6%) of the MIM thick film capacitors, which may get application to megahertz regions. The further developments of the LMCEP process for fabricating MIM thick film capacitors are also investigated

  16. Frequency characteristics of the MIM thick film capacitors fabricated by laser micro-cladding electronic pastes

    Energy Technology Data Exchange (ETDEWEB)

    Cao Yu; Li Xiangyou [Wuhan National Laboratory for Optoelectronics, Huazhong University of Sci and Tech, 430074 Wuhan, Hubei (China); Zeng Xiaoyan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Sci and Tech, 430074 Wuhan, Hubei (China)], E-mail: xyzeng@mail.hust.edu.cn

    2008-05-25

    With rapid development of the electronic industry, how to respond the market requests quickly, shorten R and D prototyping fabrication period, and reduce the cost of the electronic devices have become a challenge work, which need flexible manufacturing methods. In this work, two direct write processing methods, direct material deposition by microPen and Nd:YAG laser micro-cladding, are integrated with CAD/CAM technology for the hybrid fabrication of passive electronic components. Especially, the metal-insulator-metal (MIM) type thick film capacitors are fabricated on ceramic substrates by this method. A basic two-step procedure of laser micro-cladding electronic pastes (LMCEPs) process for the thick film pattern preparation is presented. For a better understanding of the MIM thick film capacitor characterization, equivalent circuit models at low-frequency and high-frequency domains are introduced, respectively. The frequency characteristics tests up to 1.8 GHz of capacitance stability, equivalent series resistance (ESR), equivalent series inductance (ESL) and impendence are performed, and the results show good DC voltage stability (<2.48%), good frequency stability (<2.6%) and low dissipation factor (<0.6%) of the MIM thick film capacitors, which may get application to megahertz regions. The further developments of the LMCEP process for fabricating MIM thick film capacitors are also investigated.

  17. Computerized J-H loop tracer for soft magnetic thick films in the audio frequency range

    Directory of Open Access Journals (Sweden)

    Loizos G.

    2014-07-01

    Full Text Available A computerized J-H loop tracer for soft magnetic thick films in the audio frequency range is described. It is a system built on a PXI platform combining PXI modules for control signal generation and data acquisition. The physiscal signals are digitized and the respective data strems are processed, presented and recorded in LabVIEW 7.0.

  18. Frequency selective bolometer development at Argonne National Laboratory

    Science.gov (United States)

    Datesman, Aaron; Pearson, John; Wang, Gensheng; Yefremenko, Volodymyr; Divan, Ralu; Downes, Thomas; Chang, Clarence; McMahon, Jeff; Meyer, Stephan; Carlstrom, John; Logan, Daniel; Perera, Thushara; Wilson, Grant; Novosad, Valentyn

    2008-07-01

    We discuss the development, at Argonne National Laboratory, of a four-pixel camera suitable for photometry of distant dusty galaxies located by Spitzer and SCUBA, and for study of other millimeter-wave sources such as ultra-luminous infrared galaxies, the Sunyaev-Zeldovich (SZ) effect in clusters, and galactic dust. Utilizing Frequency Selective Bolometers (FSBs) with superconducting Transition-Edge Sensors (TESs), each of the camera's four pixels is sensitive to four colors, with frequency bands centered approximately at 150, 220, 270, and 360 GHz. The current generation of these devices utilizes proximity effect superconducting bilayers of Mo/Au or Ti/Au for TESs, along with frequency selective circuitry on membranes of silicon nitride 1 cm across and 1 micron thick. The operational properties of these devices are determined by this circuitry, along with thermal control structures etched into the membranes. These etched structures do not perforate the membrane, so that the device is both comparatively robust mechanically and carefully tailored in terms of its thermal transport properties. In this paper, we report on development of the superconducting bilayer TES technology and characterization of the FSB stacks. This includes the use of new materials, the design and testing of thermal control structures, the introduction of desirable thermal properties using buried layers of crystalline silicon underneath the membrane, detector stability control, and optical and thermal test results. The scientific motivation, FSB design, FSB fabrication, and measurement results are discussed.

  19. Frequency Selective Surface for Structural Health Monitoring

    Science.gov (United States)

    Norlyana Azemi, Saidatul; Mustaffa, Farzana Hazira Wan; Faizal Jamlos, Mohd; Abdullah Al-Hadi, Azremi; Soh, Ping Jack

    2018-03-01

    Structural health monitoring (SHM) technologies have attained attention to monitor civil structures. SHM sensor systems have been used in various civil structures such as bridges, buildings, tunnels and so on. However the previous sensor for SHM is wired and encounter with problem to cover large areas. Therefore, wireless sensor was introduced for SHM to reduce network connecting problem. Wireless sensors for Structural Health monitoring are new technology and have many advantages to overcome the drawback of conventional and wired sensor. This project proposed passive wireless SHM sensor using frequency selective surface (FSS) as an alternative to conventional sensors. The electromagnetic wave characteristic of FSS will change by geometrical changes of FSS due to mechanical strain or structural failure. The changes feature is used as a sensing function without any connecting wires. Two type of design which are circular ring and square loop along with the transmission and reflection characteristics of SHM using FSS were discussed in this project. A simulation process has shown that incident angle characteristics can be use as a data for SHM application.

  20. Analytic clock frequency selection for global DVFS

    NARCIS (Netherlands)

    Gerards, Marco Egbertus Theodorus; Hurink, Johann L.; Holzenspies, P.K.F.; Kuper, Jan; Smit, Gerardus Johannes Maria

    2014-01-01

    Computers can reduce their power consumption by decreasing their speed using Dynamic Voltage and Frequency Scaling (DVFS). A form of DVFS for multicore processors is global DVFS, where the voltage and clock frequency is shared among all processor cores. Because global DVFS is efficient and cheap to

  1. Selective paint coatings for coloured solar absorbers: Polyurethane thickness insensitive spectrally selective (TISS) paints (Part II)

    Energy Technology Data Exchange (ETDEWEB)

    Orel, B.; Spreizer, H.; Surca Vuk, A.; Fir, M. [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Merlini, D.; Vodlan, M. [Color d.d., Cesta komandanta Staneta 4, SI-1230 Medvode (Slovenia); Koehl, M. [Fraunhofer-Institute for Solar Energy Systems ISE, Heidenhofstr. 2, D-79110 Freiburg (Germany)

    2007-01-23

    Red, green and blue paints were prepared for use as thickness insensitive spectrally selective (TISS) paint coatings for solar facade absorbers. The paints were composed of a polyurethane resin binder in which various pigments were incorporated in such a way that they formed stable paint dispersions, satisfying stability criteria for facade coatings. A low emittance of the paints was achieved by using low-emittance aluminium flake pigments combined with iron oxide (red coloured paints). Black pigment was added to adjust solar absorptance. Blue and green paints were made by the addition of coloured aluminium flake pigment and the solar absorptance was also adjusted by the addition of black pigment. Efficiency for photo-thermal conversion of solar radiation was assessed by evaluation of the corresponding performance criteria, which enabled the selection of paints whose performance criteria values were higher than 0 (spectrally non-selective black coating). The results confirmed that blue and green paints and to minor extent red ones, combined selectivity with colour. The morphology of the paints was assessed, revealing that the colours originated from the deposition of finely dispersed colour and/or black pigment on the surface of the aluminium flakes during paint preparation. (author)

  2. Controlling Fluences of Reactive Species Produced by Multipulse DBDs onto Wet Tissue: Frequency and Liquid Thickness

    Science.gov (United States)

    Tian, Wei; Kushner, Mark J.

    2015-09-01

    Tissue covered by a thin liquid layer treated by atmospheric pressure plasmas for biomedical applications ultimately requires a reproducible protocol for human healthcare. The outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) depend on the plasma dose which determines the integral fluences of radicals and ions onto the tissue. These fluences are controlled in part by frequency and liquid thickness. In this paper, we report on results from a computational investigation of multipulse DBDs interacting with wet tissue. The DBDs were simulated for 100 stationary or random streamers at different repetition rates and liquid thicknesses followed by 10 s to 2 min of afterglow. At 100 Hz, NOaq and OHaq are mixed by randomly striking streamers, although they have different rates of solvation. NOaq is nearly completely consumed by reactions with OHaq at the liquid surface. Only H2O2aq, produced through OHaq mutual reactions, survives to reach the tissue. After 100 pulses, the liquid becomes ozone-rich, in which the nitrous ion, NO2-aq, is converted to the nitric ion, NO3-aq. Reducing the pulse frequency to 10 Hz results in significant fluence of NOaq to the tissue as NOaq can escape during the interpulse period from the liquid surface where OHaq is formed. For the same reason, NO2-aq can also reach deeper into the liquid at lower frequency. Frequency and thickness of the liquid are methods to control the plasma produced aqueous species to the underlying tissue. Work supported by DOE (DE-SC0001319) and NSF (CHE-1124724).

  3. Vibration-response due to thickness loss on steel plate excited by resonance frequency

    Science.gov (United States)

    Kudus, S. A.; Suzuki, Y.; Matsumura, M.; Sugiura, K.

    2018-04-01

    The degradation of steel structure due to corrosion is a common problem found especially in the marine structure due to exposure to the harsh marine environment. In order to ensure safety and reliability of marine structure, the damage assessment is an indispensable prerequisite for plan of remedial action on damaged structure. The main goal of this paper is to discuss simple vibration measurement on plated structure to give image on overview condition of the monitored structure. The changes of vibration response when damage was introduced in the plate structure were investigated. The damage on plate was simulated in finite element method as loss of thickness section. The size of damage and depth of loss of thickness were varied for different damage cases. The plate was excited with lower order of resonance frequency in accordance estimate the average remaining thickness based on displacement response obtain in the dynamic analysis. Significant reduction of natural frequency and increasing amplitude of vibration can be observed in the presence of severe damage. The vibration analysis summarized in this study can serve as benchmark and reference for researcher and design engineer.

  4. Analytic clock frequency selection for global DVFS

    OpenAIRE

    Gerards, Marco Egbertus Theodorus; Hurink, Johann L.; Holzenspies, P.K.F.; Kuper, Jan; Smit, Gerardus Johannes Maria

    2014-01-01

    Computers can reduce their power consumption by decreasing their speed using Dynamic Voltage and Frequency Scaling (DVFS). A form of DVFS for multicore processors is global DVFS, where the voltage and clock frequency is shared among all processor cores. Because global DVFS is efficient and cheap to implement, it is used in modern multicore processors like the IBM Power 7, ARM Cortex A9 and NVIDIA Tegra 2. This theory oriented paper discusses energy optimal DVFS algorithms for such processors....

  5. CO2 Selective Potentiometric Sensor in Thick-film Technology

    Directory of Open Access Journals (Sweden)

    Ralf Moos

    2008-08-01

    Full Text Available A potentiometric sensor device based on screen-printed Nasicon films was investigated. In order to transfer the promising sensor concept of an open sodium titanate reference to thick film technology, “sodium-rich” and “sodium-poor” formulations were compared. While the “sodium-rich” composition was found to react with the ion conducting Nasicon during thermal treatment, the “sodium-poor” reference mixture was identified as an appropriate reference composition. Screen-printed sensor devices were prepared and tested with respect to CO2 response, reproducibility, and cross-interference of oxygen. Excellent agreement with the theory was observed. With the integration of a screen-printed heater, sensor elements were operated actively heated in a cold gas stream.

  6. Measuring Auditory Selective Attention using Frequency Tagging

    Directory of Open Access Journals (Sweden)

    Hari M Bharadwaj

    2014-02-01

    Full Text Available Frequency tagging of sensory inputs (presenting stimuli that fluctuate periodically at rates to which the cortex can phase lock has been used to study attentional modulation of neural responses to inputs in different sensory modalities. For visual inputs, the visual steady-state response (VSSR at the frequency modulating an attended object is enhanced, while the VSSR to a distracting object is suppressed. In contrast, the effect of attention on the auditory steady-state response (ASSR is inconsistent across studies. However, most auditory studies analyzed results at the sensor level or used only a small number of equivalent current dipoles to fit cortical responses. In addition, most studies of auditory spatial attention used dichotic stimuli (independent signals at the ears rather than more natural, binaural stimuli. Here, we asked whether these methodological choices help explain discrepant results. Listeners attended to one of two competing speech streams, one simulated from the left and one from the right, that were modulated at different frequencies. Using distributed source modeling of magnetoencephalography results, we estimate how spatially directed attention modulates the ASSR in neural regions across the whole brain. Attention enhances the ASSR power at the frequency of the attended stream in the contralateral auditory cortex. The attended-stream modulation frequency also drives phase-locked responses in the left (but not right precentral sulcus (lPCS, a region implicated in control of eye gaze and visual spatial attention. Importantly, this region shows no phase locking to the distracting stream suggesting that the lPCS in engaged in an attention-specific manner. Modeling results that take account of the geometry and phases of the cortical sources phase locked to the two streams (including hemispheric asymmetry of lPCS activity help partly explain why past ASSR studies of auditory spatial attention yield seemingly contradictory

  7. Numerical Determination of Natural Frequencies and Modes of the Vibrations of a Thick-Walled Cylindrical Shell

    Science.gov (United States)

    Grigorenko, A. Ya.; Borisenko, M. Yu.; Boichuk, E. V.; Prigoda, A. P.

    2018-01-01

    The dynamic characteristics of a thick-walled cylindrical shell are determined numerically using the finite-element method implemented with licensed FEMAR software. The natural frequencies and modes are compared with those obtained earlier experimentally by the method of stroboscopic holographic interferometry. Frequency coefficients demonstrating how the natural frequency depends on the physical and mechanical parameters of the material are determined.

  8. 47 CFR 90.723 - Selection and assignment of frequencies.

    Science.gov (United States)

    2010-10-01

    ... 220-222 MHz Band § 90.723 Selection and assignment of frequencies. (a) Phase II applications for frequencies in the 220-222 MHz band shall specify whether their intended use is for 10-channel nationwide... medical use. Phase II applicants for frequencies for public safety/mutual aid use or emergency medical use...

  9. On selecting a sensitive region thickness of a silicon semiconductor detector for operation under counting conditions

    International Nuclear Information System (INIS)

    Pronkin, N.S.; Khakhalin, V.V.

    1972-01-01

    The paper discusses the selection of a thickness of a sensitive area of a silicon semiconductor detector, used in the count regime based on the signal to noise ratio and β-radiation registration efficiency. (author)

  10. Selection of the ''best'' model for converting beta backscatter count readings into thickness measurements

    International Nuclear Information System (INIS)

    Smiriga, N.G.

    1976-01-01

    This report compares two models for converting beta backscatter count readings into thickness measurements. The necessary formulas to be used in an unweighted and weighted regression analysis are listed. The question of whether one should perform a regression analysis using the five available standard thicknesses or whether one should, in addition to these standard thicknesses, use zero as a standard thickness is decided. A weighted regression analysis is compared with an unweighted one for each model. The ''best'' model is selected, and the conclusions of the analysis are presented

  11. Comparison of high-resolution Scheimpflug and high-frequency ultrasound biomicroscopy to anterior-segment OCT corneal thickness measurements

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2013-11-01

    Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis1 1Laservision.gr Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USA Background: The purpose of this study was to compare and correlate central corneal thickness in healthy, nonoperated eyes with three advanced anterior-segment imaging systems: a high-resolution Scheimpflug tomography camera (Oculyzer II, a spectral-domain anterior-segment optical coherence tomography (AS-OCT system, and a high-frequency ultrasound biomicroscopy (HF-UBM system. Methods: Fifty eyes randomly selected from 50 patients were included in the study. Inclusion criteria were healthy, nonoperated eyes examined consecutively by the same examiner. Corneal imaging was performed by three different methods, ie, Oculyzer II, spectral-domain AS-OCT, and FH-UBM. Central corneal thickness measurements were compared using scatter diagrams, Bland-Altman plots (with bias and 95% confidence intervals, and two-paired analysis. Results: The coefficient of determination (r2 between the Oculyzer II and AS-OCT measurements was 0.895. Likewise, the coefficient was 0.893 between the Oculyzer II and HF-UBM and 0.830 between the AS-OCT and HF-UBM. The trend line coefficients of linearity were 0.925 between the Oculyzer II and the AS-OCT, 1.006 between the Oculyzer II and HF-UBM, and 0.841 between the AS-OCT and HF-UBM. The differences in average corneal thickness between the three pairs of CCT measurements were –6.86 µm between the Oculyzer II and HF-UBM, –12.20 µm between the AS-OCT and Oculyzer II, and +19.06 µm between the HF-UBM and AS-OCT. Conclusion: The three methods used for corneal thickness measurement are highly correlated. Compared with the Scheimplug and ultrasound devices, the AS-OCT appears to report a more accurate, but overally thinner corneal pachymetry. Keywords: anterior eye segment, high-frequency ultrasound biomicroscopy, optical coherence tomography, high-resolution Pentacam

  12. Metamaterial near-field sensor for deep-subwavelength thickness measurements and sensitive refractometry in the terahertz frequency range

    International Nuclear Information System (INIS)

    Reinhard, Benjamin; Schmitt, Klemens M.; Neu, Jens; Wollrab, Viktoria; Beigang, Rene; Rahm, Marco

    2012-01-01

    We present a metamaterial-based terahertz (THz) sensor for thickness measurements of subwavelength-thin materials and refractometry of liquids and liquid mixtures. The sensor operates in reflection geometry and exploits the frequency shift of a sharp Fano resonance minimum in the presence of dielectric materials. We obtained a minimum thickness resolution of 12.5 nm (1/16 000 times the wavelength of the THz radiation) and a refractive index sensitivity of 0.43 THz per refractive index unit. We support the experimental results by an analytical model that describes the dependence of the resonance frequency on the sample material thickness and the refractive index.

  13. Metamaterial near-field sensor for deep-subwavelength thickness measurements and sensitive refractometry in the terahertz frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Reinhard, Benjamin; Schmitt, Klemens M.; Neu, Jens [Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern (Germany); Wollrab, Viktoria; Beigang, Rene; Rahm, Marco [Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern (Germany); Fraunhofer Institute for Physical Measurement Techniques IPM, 79110 Freiburg (Germany)

    2012-05-28

    We present a metamaterial-based terahertz (THz) sensor for thickness measurements of subwavelength-thin materials and refractometry of liquids and liquid mixtures. The sensor operates in reflection geometry and exploits the frequency shift of a sharp Fano resonance minimum in the presence of dielectric materials. We obtained a minimum thickness resolution of 12.5 nm (1/16 000 times the wavelength of the THz radiation) and a refractive index sensitivity of 0.43 THz per refractive index unit. We support the experimental results by an analytical model that describes the dependence of the resonance frequency on the sample material thickness and the refractive index.

  14. Frequency selective tunable spin wave channeling in the magnonic network

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Odincov, S. A.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Stognij, A. I. [Scientific-Practical Materials Research Center, National Academy of Sciences of Belarus, 220072 Minsk (Belarus)

    2016-04-25

    Using the space-resolved Brillouin light scattering spectroscopy, we study the frequency and wavenumber selective spin-wave channeling. We demonstrate the frequency selective collimation of spin-wave in an array of magnonic waveguides, formed between the adjacent magnonic crystals on the surface of yttrium iron garnet film. We show the control over spin-wave propagation length by the orientation of an in-plane bias magnetic field. Fabricated array of magnonic crystal can be used as a magnonic platform for multidirectional frequency selective signal processing applications in magnonic networks.

  15. Frequency-Selective Attention in Auditory Scenes Recruits Frequency Representations Throughout Human Superior Temporal Cortex.

    Science.gov (United States)

    Riecke, Lars; Peters, Judith C; Valente, Giancarlo; Kemper, Valentin G; Formisano, Elia; Sorger, Bettina

    2017-05-01

    A sound of interest may be tracked amid other salient sounds by focusing attention on its characteristic features including its frequency. Functional magnetic resonance imaging findings have indicated that frequency representations in human primary auditory cortex (AC) contribute to this feat. However, attentional modulations were examined at relatively low spatial and spectral resolutions, and frequency-selective contributions outside the primary AC could not be established. To address these issues, we compared blood oxygenation level-dependent (BOLD) responses in the superior temporal cortex of human listeners while they identified single frequencies versus listened selectively for various frequencies within a multifrequency scene. Using best-frequency mapping, we observed that the detailed spatial layout of attention-induced BOLD response enhancements in primary AC follows the tonotopy of stimulus-driven frequency representations-analogous to the "spotlight" of attention enhancing visuospatial representations in retinotopic visual cortex. Moreover, using an algorithm trained to discriminate stimulus-driven frequency representations, we could successfully decode the focus of frequency-selective attention from listeners' BOLD response patterns in nonprimary AC. Our results indicate that the human brain facilitates selective listening to a frequency of interest in a scene by reinforcing the fine-grained activity pattern throughout the entire superior temporal cortex that would be evoked if that frequency was present alone. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Frequency selective surfaces integrated with phased array antennas

    NARCIS (Netherlands)

    Monni, S.

    2005-01-01

    Frequency Selective Surfaces (FSS's) are periodic arrays of patches and/or slots etched on a metal plate, having frequency and angular ??ltering properties. The FSS response to an excitation (for example a plane wave) is characterized in terms of its re ection and transmission coe??cient, and

  17. Miniaturized, Planar Ion-selective Electrodes Fabricated by Means of Thick-film Technology

    Directory of Open Access Journals (Sweden)

    Robert Koncki

    2006-04-01

    Full Text Available Various planar technologies are employed for developing solid-state sensorshaving low cost, small size and high reproducibility; thin- and thick-film technologies aremost suitable for such productions. Screen-printing is especially suitable due to itssimplicity, low-cost, high reproducibility and efficiency in large-scale production. Thistechnology enables the deposition of a thick layer and allows precise pattern control.Moreover, this is a highly economic technology, saving large amounts of the used inks. Inthe course of repetitions of the film-deposition procedure there is no waste of material dueto additivity of this thick-film technology. Finally, the thick films can be easily and quicklydeposited on inexpensive substrates. In this contribution, thick-film ion-selective electrodesbased on ionophores as well as crystalline ion-selective materials dedicated forpotentiometric measurements are demonstrated. Analytical parameters of these sensors arecomparable with those reported for conventional potentiometric electrodes. All mentionedthick-film strip electrodes have been totally fabricated in only one, fully automated thick-film technology, without any additional manual, chemical or electrochemical steps. In allcases simple, inexpensive, commercially available materials, i.e. flexible, plastic substratesand easily cured polymer-based pastes were used.

  18. Low-frequency noise in high-Tc superconducting thick films

    International Nuclear Information System (INIS)

    Aponte, J.M.; Gutierrez, G.; Octavio, M.

    1990-01-01

    In this paper experimental results on the resistance noise in thick films of YBa 2 Cu 3 O 7-δ in the vicinity of the superconducting transition are reported. The measurements were performed in samples with broad resistive transitions and in the frequency range from 1Hz to 100 Hz. The power spectral density S v /V 2 of the excess noise is obtained by subtracting the current-independent background noise from the total measured noise. The authors observed that at the transition, the magnitude of S v /V 2 rises above its level at room temperature exhibiting peaks at the same temperatures at which R -1 dR/dT has maxima. The authors performed measurements of S v /V 2 as a function of the current through the sample and the authors found that it diverges as the critical current is approached from above and that it is zero below the critical current. This transition is found to be described quite well by a percolation model

  19. Thin film thickness measurement error reduction by wavelength selection in spectrophotometry

    International Nuclear Information System (INIS)

    Tsepulin, Vladimir G; Perchik, Alexey V; Tolstoguzov, Victor L; Karasik, Valeriy E

    2015-01-01

    Fast and accurate volumetric profilometry of thin film structures is an important problem in the electronic visual display industry. We propose to use spectrophotometry with a limited number of working wavelengths to achieve high-speed control and an approach to selecting the optimal working wavelengths to reduce the thickness measurement error. A simple expression for error estimation is presented and tested using a Monte Carlo simulation. The experimental setup is designed to confirm the stability of film thickness determination using a limited number of wavelengths

  20. Regolith thickness over Sinus Iridum: Results from morphology and size-frequency distribution of small impact craters

    Science.gov (United States)

    Fa, Wenzhe; Liu, Tiantian; Zhu, Meng-Hua; Haruyama, Junichi

    2014-08-01

    High-resolution optical images returned from recent lunar missions provide a new chance for estimation of lunar regolith thickness using morphology and the size-frequency distribution of small impact craters. In this study, regolith thickness over the Sinus Iridum region is estimated using Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Cameras (NACs) images. A revised relationship between crater geometry and regolith thickness is proposed based on old experimental data that takes into considering the effect of the illumination angle of the images. In total, 227 high-resolution LROC NAC images are used, and 378,556 impact craters with diameters from 4.2 to 249.8 m are counted, and their morphologies are identified. Our results show that 50% of the Sinus Iridum region has a regolith thickness between 5.1 and 10.7 m, and the mean and median regolith thicknesses are 8.5 and 8.0 m, respectively. There are substantial regional variations in the regolith thickness, with its median value varying from 2.6 to 12.0 m for most regions. Local variations of regolith thickness are found to be correlated with the lunar surface age: the older the surface, the greater the thickness. In addition, sporadically distributed impact ejecta and crater rays are associated with relatively larger regolith thickness, which might result from excavation and transport of materials during the formation of the secondaries of Copernican-aged craters. Our estimated regolith thickness can help with future analysis of Chang'E-3 lunar penetrating radar echoes and studies of the subsurface stratigraphic structure of the Moon.

  1. Integral criterion for selecting nonlinear crystals for frequency conversion

    International Nuclear Information System (INIS)

    Grechin, Sergei G

    2009-01-01

    An integral criterion, which takes into account all parameters determining the conversion efficiency, is offered for selecting nonlinear crystals for frequency conversion. The angular phase-matching width is shown to be related to the beam walk-off angle. (nonlinear optical phenomena)

  2. Consequences of peripheral frequency selectivity for nonsimultaneous masking

    NARCIS (Netherlands)

    Duifhuis, H.

    1973-01-01

    The frequency selectivity of the peripheral ear (e.g., at the VIIIth nerve level) is so acute that onset and offset transients in responses to short signals produce a nonnegligible extension of the signal duration. Thus, peripheral excitation patterns produced by signals which were separated in time

  3. Characteristics of spectro-temporal modulation frequency selectivity in humans.

    Science.gov (United States)

    Oetjen, Arne; Verhey, Jesko L

    2017-03-01

    There is increasing evidence that the auditory system shows frequency selectivity for spectro-temporal modulations. A recent study of the authors has shown spectro-temporal modulation masking patterns that were in agreement with the hypothesis of spectro-temporal modulation filters in the human auditory system [Oetjen and Verhey (2015). J. Acoust. Soc. Am. 137(2), 714-723]. In the present study, that experimental data and additional data were used to model this spectro-temporal frequency selectivity. The additional data were collected to investigate to what extent the spectro-temporal modulation-frequency selectivity results from a combination of a purely temporal amplitude-modulation filter and a purely spectral amplitude-modulation filter. In contrast to the previous study, thresholds were measured for masker and target modulations with opposite directions, i.e., an upward pointing target modulation and a downward pointing masker modulation. The comparison of this data set with previous corresponding data with the same direction from target and masker modulations indicate that a specific spectro-temporal modulation filter is required to simulate all aspects of spectro-temporal modulation frequency selectivity. A model using a modified Gabor filter with a purely temporal and a purely spectral filter predicts the spectro-temporal modulation masking data.

  4. Cavity-soliton laser with frequency-selective feedback

    International Nuclear Information System (INIS)

    Scroggie, A. J.; Firth, W. J.; Oppo, G.-L.

    2009-01-01

    We present a coupled-cavity model of a laser with frequency-selective feedback, and use it to analyze and explain the existence of stationary and dynamic spatial solitons in the device. Particular features of soliton addressing in this system are discussed. We demonstrate the advantages of our model with respect to the common Lang-Kobayashi approximation.

  5. Frequency Selective Surfaces for extended Bandwidth backing reflector functions

    NARCIS (Netherlands)

    Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

    2008-01-01

    This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

  6. The effect of training frequency on selected physical and ...

    African Journals Online (AJOL)

    They were randomly selected into 3 groups of 20 each. Groups A and B served as the training groups while group C formed the control group which remained sedentary, and followed their normal lifestyle. The experimental groups (A & B) initially trained for 12 weeks at a training frequency of 3 times a week. This was ...

  7. Spectro-temporal modulation masking patterns reveal frequency selectivity.

    Science.gov (United States)

    Oetjen, Arne; Verhey, Jesko L

    2015-02-01

    The present study investigated the possibility that the human auditory system demonstrates frequency selectivity to spectro-temporal amplitude modulations. Threshold modulation depth for detecting sinusoidal spectro-temporal modulations was measured using a generalized masked threshold pattern paradigm with narrowband masker modulations. Four target spectro-temporal modulations were examined, differing in their temporal and spectral modulation frequencies: a temporal modulation of -8, 8, or 16 Hz combined with a spectral modulation of 1 cycle/octave and a temporal modulation of 4 Hz combined with a spectral modulation of 0.5 cycles/octave. The temporal center frequencies of the masker modulation ranged from 0.25 to 4 times the target temporal modulation. The spectral masker-modulation center-frequencies were 0, 0.5, 1, 1.5, and 2 times the target spectral modulation. For all target modulations, the pattern of average thresholds for the eight normal-hearing listeners was consistent with the hypothesis of a spectro-temporal modulation filter. Such a pattern of modulation-frequency sensitivity was predicted on the basis of psychoacoustical data for purely temporal amplitude modulations and purely spectral amplitude modulations. An analysis of separability indicates that, for the present data set, selectivity in the spectro-temporal modulation domain can be described by a combination of a purely spectral and a purely temporal modulation filter function.

  8. Frequency Selection for Multi-frequency Acoustic Measurement of Suspended Sediment

    Science.gov (United States)

    Chen, X.; HO, H.; Fu, X.

    2017-12-01

    Multi-frequency acoustic measurement of suspended sediment has found successful applications in marine and fluvial environments. Difficult challenges remain in regard to improving its effectiveness and efficiency when applied to high concentrations and wide size distributions in rivers. We performed a multi-frequency acoustic scattering experiment in a cylindrical tank with a suspension of natural sands. The sands range from 50 to 600 μm in diameter with a lognormal size distribution. The bulk concentration of suspended sediment varied from 1.0 to 12.0 g/L. We found that the commonly used linear relationship between the intensity of acoustic backscatter and suspended sediment concentration holds only at sufficiently low concentrations, for instance below 3.0 g/L. It fails at a critical value of concentration that depends on measurement frequency and the distance between the transducer and the target point. Instead, an exponential relationship was found to work satisfactorily throughout the entire range of concentration. The coefficient and exponent of the exponential function changed, however, with the measuring frequency and distance. Considering the increased complexity of inverting the concentration values when an exponential relationship prevails, we further analyzed the relationship between measurement error and measuring frequency. It was also found that the inversion error may be effectively controlled within 5% if the frequency is properly set. Compared with concentration, grain size was found to heavily affect the selection of optimum frequency. A regression relationship for optimum frequency versus grain size was developed based on the experimental results.

  9. Effect of Reduced Meal Frequency during Ramadan Fasting on Retinal and Choroidal Thickness.

    Science.gov (United States)

    Ersan, Ismail; Tufan, Hasan Ali; Arikan, Sedat; Kara, Selcuk; Gencer, Baran; Hondur, Ahmet Murat

    2017-01-01

    To evaluate the effects of Ramadan fasting on central foveal thickness (CFT) and subfoveal choroidal thickness (SFCT) in healthy individuals using enhanced depth imaging optical coherence tomography (EDI-OCT). The EDI-OCT scans of 42 healthy individuals obtained after about 12 hours of fasting on at least the twenty-first consecutive day of fasting were compared to scans of the same patients taken one month after the last day they had fasted. CFT values were similar for both time periods (p > 0.05). The SFCT was significantly higher after consecutive fasting days towards the end of Ramadan, compared to the SFCT after one month of no fasting (one month after Ramadan ended) (p Ramadan fasting may lead to a significant increase in subfoveal choroidal thickness without affecting the central foveal thickness.

  10. Analysis of Various Frequency Selective Shielding Glass by FDTD method

    OpenAIRE

    笠嶋, 善憲; Kasashima, Yoshinori

    2012-01-01

    A frequency Selective shielding (FSS) glass is a print of many same size antennas on a sheet of glass, and it has high shielding properties for one specific frequency. This time, the author analyzed characteristics of various FSSs whose antenna types are different by FDTD method. The antenna types are cross dipole, circular loop, square loop, circular patch, and square patch. As the result, the FSSs can be composed of the various types of the antennas, and the FSSs have broad-band shielding c...

  11. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

    Directory of Open Access Journals (Sweden)

    Xuezhi Shi

    2016-12-01

    Full Text Available To increase building rate and save cost, the selective laser melting (SLM of Ti6Al4V with a high layer thickness (200 μm and low cost coarse powders (53 μm–106 μm at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm3/s, which is about 2 times–9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  12. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V.

    Science.gov (United States)

    Shi, Xuezhi; Ma, Shuyuan; Liu, Changmeng; Chen, Cheng; Wu, Qianru; Chen, Xianping; Lu, Jiping

    2016-12-01

    To increase building rate and save cost, the selective laser melting (SLM) of Ti6Al4V with a high layer thickness (200 μm) and low cost coarse powders (53 μm-106 μm) at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm³/s, which is about 2 times-9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  13. Mechanical stress-controlled tunable active frequency-selective surface

    Science.gov (United States)

    Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

    2017-01-01

    This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

  14. Selection of the wavelet function for the frequencies estimation

    International Nuclear Information System (INIS)

    Garcia R, A.

    2007-01-01

    At the moment the signals are used to diagnose the state of the systems, by means of the extraction of their more important characteristics such as the frequencies, tendencies, changes and temporary evolutions. This characteristics are detected by means of diverse analysis techniques, as Autoregressive methods, Fourier Transformation, Fourier transformation in short time, Wavelet transformation, among others. The present work uses the one Wavelet transformation because it allows to analyze stationary, quasi-stationary and transitory signals in the time-frequency plane. It also describes a methodology to select the scales and the Wavelet function to be applied the one Wavelet transformation with the objective of detecting to the dominant system frequencies. (Author)

  15. Design of Nonuniform Filter Bank Transceivers for Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Yuan-Pei Lin

    2007-01-01

    Full Text Available In recent years, there has been considerable interest in the theory and design of filter bank transceivers due to their superior frequency response. In many applications, it is desired to have transceivers that can support multiple services with different incoming data rates and different quality-of-service requirements. To meet these requirements, we can either do resource allocation or design transceivers with a nonuniform bandwidth partition. In this paper, we propose a method for the design of nonuniform filter bank transceivers for frequency selective channels. Both frequency response and signal-to-interference ratio (SIR can be incorporated in the transceiver design. Moreover, the technique can be extended to the case of nonuniform filter bank transceivers with rational sampling factors. Simulation results show that nonuniform filter bank transceivers with good filter responses as well as high SIR can be obtained by the proposed design method.

  16. Effect of photonic crystal and frequency selective surface implementation on gain enhancement in the microstrip patch antenna at terahertz frequency

    Energy Technology Data Exchange (ETDEWEB)

    Nejati, Ameneh, E-mail: ameneh.nejati@gmail.com [Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Sadeghzadeh, Ramezan Ali [Faculty of Electrical and Computer Engineering, K.N Toosi University of Technology, Tehran (Iran, Islamic Republic of); Geran, Fatemeh [Faculty of Electrical and Computer Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of)

    2014-09-15

    In this paper, microstrip patch antenna with frequency selective surface (FSS) and photonic band gap (PBG) structures in the frequency range of 0.5–0.7 THz is presented for wireless communications. Proposed patch antenna is designed on a substrate with uniform and non-uniform PBG structures. Here, the effects of substrate thickness, various radii and arrangement of holes on antenna resonance in both PBG forms are studied. Near zero characteristic on uniform and non-uniform PBG substrate is compared and the results show that along with increase in hole radius, antenna operating frequency and bandwidth are increased. Also, the FSS structure is designed as a perfect absorber. Finally, by using FSS and PBG structures simultaneously, gain enhancement, increase in directivity and pattern shaping are studied at THz field. The antenna gain in final structure is increased by 2 dBi (32%) in comparison to simple form and Half-Power beam width is reduced from 100°×80° in simple form to 72°×48° by using FSS and PBG. All simulations and designs are done by Ansoft HFSS and CST Microwave Studio simulation tools with different full wave methods.

  17. High-frequency internal waves and thick bottom mixed layers observed by gliders in the Gulf Stream

    Science.gov (United States)

    Todd, Robert E.

    2017-06-01

    Autonomous underwater gliders are conducting high-resolution surveys within the Gulf Stream along the U.S. East Coast. Glider surveys reveal two mechanisms by which energy is extracted from the Gulf Stream as it flows over the Blake Plateau, a portion of the outer continental shelf between Florida and North Carolina where bottom depths are less than 1000 m. Internal waves with vertical velocities exceeding 0.1 m s-1 and frequencies just below the local buoyancy frequency are routinely found over the Blake Plateau, particularly near the Charleston Bump, a prominent topographic feature. These waves are likely internal lee waves generated by the subinertial Gulf Stream flow over the irregular bathymetry of the outer continental shelf. Bottom mixed layers with O(100) m thickness are also frequently encountered; these thick bottom mixed layers likely form in the lee of topography due to enhanced turbulence generated by O(1) m s-1 near-bottom flows.

  18. The effect of the gas factor on selecting the thickness of a layer during two-layer getting of thick seams. [USSR

    Energy Technology Data Exchange (ETDEWEB)

    Varekha, Zh P; Kurkin, A S; Vechera, V N

    1979-01-01

    For technico-economic verification of the selection of the efficient removed thickness of upper and lower layers under conditions of high gas abundance of seams, the KNIUI has developed an economic model of converted costs within a getting field, allowing for natural and technical factors. The calculation considers specific costs for stoping work when getting the upper and lower layers, digging and maintenance of development workings, coal transport, assembly-disassembly work, ventilation, labor costs, degassing, etc. The calculation dependences and nomogram obtained enable comparatively easy definition of efficient thicknesses of removed layers when designing stoping work at thick, gently sloping seams, as well as calculation converted costs using as the initial data the total thickness of the seam, its natural gas content, and the expected degree of preliminary degassing.

  19. Increased carotid intima thickness and decreased media thickness in premenopausal women with systemic lupus erythematosus: an investigation by non-invasive high-frequency ultrasound.

    Science.gov (United States)

    Leonard, D; Akhter, T; Nordmark, G; Rönnblom, L; Naessen, T

    2011-01-01

    To determine whether high-frequency ultrasound (US) yielding separate assessments of intima and media thickness gives additional information about the vascular morphology compared with the total common carotid artery intima-media thickness (CCA-IMT). Using a 22 MHz US instrument, we determined the near-wall CCA-IMT, the intima and media layers, and the intima/media (I/M) ratio in 47 premenopausal women with systemic lupus erythematosus (SLE), 20 healthy women, and 17 postmenopausal women (mean ages 37, 40, and 69 years, respectively). In SLE, the carotid intima was thicker (0.19 ± 0.04 vs. 0.12 ± 0.02 mm), the media thinner (0.45 ± 0.12 vs. 0.68 ± 0.24 mm), the I/M ratio higher (0.45 ± 0.17 vs. 0.20 ± 0.07) (all p women (0.19 ± 0.04 vs. 0.14 ± 0.03 mm, p media, and a higher I/M ratio in women with SLE compared to healthy controls and indicated an artery wall status in SLE comparable to 30-years-older healthy women. Separate estimates of carotid intima and media layers may be preferable to CCA-IMT in SLE patients.

  20. Manual B-mode versus automated radio-frequency carotid intima-media thickness measurements

    NARCIS (Netherlands)

    Dogan, Soner; Plantinga, Yvonne; Dijk, Joke M.; van der Graaf, Yolanda; Grobbee, Diederick E.; Bots, Michiel L.; Algra, N. N.; Doevendans, P. A.; Eikelboom, C.; van der Graaf, Y.; Grobbee, E.; Kappelle, L. J.; Mali, W. P. Th M.; Moll, F. L.; Rutten, G. E. H. M.; Visseren, F. L. J.

    2009-01-01

    Carotid intima-media thickness (CIMT) serves as an indicator of atherosclerosis and cardiovascular risk. Manual measurements of B-mode ultrasound images are the most applied method. Automated measurements with radiofrequency (RF) ultrasound have been suggested as an alternative. The aim of this

  1. Cooperative Orthogonal Space-Time-Frequency Block Codes over a MIMO-OFDM Frequency Selective Channel

    Directory of Open Access Journals (Sweden)

    M. Rezaei

    2016-03-01

    Full Text Available In this paper, a cooperative algorithm to improve the orthogonal space-timefrequency block codes (OSTFBC in frequency selective channels for 2*1, 2*2, 4*1, 4*2 MIMO-OFDM systems, is presented. The algorithm of three node, a source node, a relay node and a destination node is formed, and is implemented in two stages. During the first stage, the destination and the relay antennas receive the symbols sent by the source antennas. The destination node and the relay node obtain the decision variables employing time-space-frequency decoding process by the received signals. During the second stage, the relay node transmits decision variables to the destination node. Due to the increasing diversity in the proposed algorithm, decision variables in the destination node are increased to improve system performance. The bit error rate of the proposed algorithm at high SNR is estimated by considering the BPSK modulation. The simulation results show that cooperative orthogonal space-time-frequency block coding, improves system performance and reduces the BER in a frequency selective channel.

  2. Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

    Science.gov (United States)

    Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

    2018-04-01

    Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f-v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

  3. Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

    Science.gov (United States)

    Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

    2018-07-01

    Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f- v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

  4. The Effect of Selected Conditions in a Thermoforming Process on Wall Thickness Variations

    Directory of Open Access Journals (Sweden)

    Emil Sasimowski

    2017-12-01

    Full Text Available The paper reports the results of a study on the effect of selected conditions in a thermoforming process for thin polystyrene sheet by vacuum assisted drape forming on the wall thickness non-uniformity of finished parts. The investigation was performed using Statistica’s DOE module for three variables: temperatures in the external and internal zones of the heater as well as heating time of the plastic sheet. The results demonstrate that the wall thickness in the finished parts at the measuring points is primarily affected by the heating time and the temperature in the internal zone of the heater, while the temperature in the external zone only affects some regions of the finished part. The results demonstrate that a short heating time and hence a lower temperature of the plastic sheet lead to a more uniform deformation of both the bottom and the side walls of the finished part, and as a consequence, to smaller variations in the wall thickness. The shortening of the heating time is however limited by the necessity of accurate reproduction of the shape of the finished part.

  5. Natural frequencies and an atlas of mode shapes for generally-laminated, thick, skew, trapezoidal plates

    OpenAIRE

    Lovejoy, Andrew Elwyn

    1994-01-01

    Composite materials are increasingly finding use in structures, such as aircraft components, and thus, an accurate method of predicting response is required. Even laminated structures that are considered thin can be significantly affected by transverse shear effects, and as a result, transverse shear should not be neglected. The free vibration response of generally-laminated, thick, skew, trapezoidal plates is investigated as there appears to be a lack of information in this ar...

  6. Repeatability and interobserver reproducibility of Artemis-2 high-frequency ultrasound in determination of human corneal thickness

    Directory of Open Access Journals (Sweden)

    Ogbuehi KC

    2012-05-01

    Full Text Available Kelechi C Ogbuehi, Uchechukwu L OsuagwuOutpatient Clinic, Department of Optometry, King Saud University, Riyadh, Kingdom of Saudi ArabiaBackground: The purpose of this study was to assess the repeatability and limits of agreement of corneal thickness values measured by a high-frequency ultrasound (Artemis-2, hand-held ultrasound pachymeter (DGH-500 and a specular microscope (SP-3000P.Methods: Central corneal thickness (CCT was analyzed in this prospective randomized study that included 32 patients (18 men and 14 women aged 21–24 years. Measurements were obtained in two sessions, one week apart, by two examiners with three devices in a randomized order. Nine measurements were taken (three with each device on one randomly selected eye of each patient in each measurement session. The coefficient of repeatability and interobserver reproducibility for the values of each method were calculated. The limits of agreement between techniques were also evaluated.Results: There were no significant differences in CCT values between sessions for each of the three devices (P > 0.05. The repeatability coefficients for the Artemis-2 (±8 µm/±9 µm were superior to those of the SP-3000P (±9 µm/±11 µm and DGH 500 (±12 µm/±12 µm in session 1/session 2 respectively, while the interobserver reproducibility index (differences between session 1 and session 2 was superior for the SP-3000P (±17 µm with respect to DHG-500 (±29 µm and the Artemis-2 (±31 µm. In session 1 and session 2, the limits of agreement between the techniques were 35 µm to -31 µm and 34 to -20 µm, respectively, for DGH-500 versus Artemis-2, 73 µm to 3 µm and 60 µm to 9 µm for Artemis-2 versus SP-3000P, and 58 µm to 22 µm and 72 µm to 10 µm for DGH-500 versus SP-3000P comparisons. The DGH-500 and Artemis-2 gave similar values (P > 0.05 in both sessions, but both (Artemis-2 and DGH-500 values were significantly greater than that of the SP-3000P (P < 0.05 in both sessions

  7. Distributive estimation of frequency selective channels for massive MIMO systems

    KAUST Repository

    Zaib, Alam

    2015-12-28

    We consider frequency selective channel estimation in the uplink of massive MIMO-OFDM systems, where our major concern is complexity. A low complexity distributed LMMSE algorithm is proposed that attains near optimal channel impulse response (CIR) estimates from noisy observations at receive antenna array. In proposed method, every antenna estimates the CIRs of its neighborhood followed by recursive sharing of estimates with immediate neighbors. At each step, every antenna calculates the weighted average of shared estimates which converges to near optimal LMMSE solution. The simulation results validate the near optimal performance of proposed algorithm in terms of mean square error (MSE). © 2015 EURASIP.

  8. Thickness-dependent coherent phonon frequency in ultrathin FeSe/SrTiO3 films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shuolong [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Sobota, Jonathan A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Leuenberger, Dominik [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Kemper, Alexander F. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lee, James J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Schmitt, Felix T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Li, Wei [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Moore, Rob G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Kirchmann, Patrick S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shen, Zhi -Xun [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)

    2015-06-01

    Ultrathin FeSe films grown on SrTiO3 substrates are a recent milestone in atomic material engineering due to their important role in understanding unconventional superconductivity in Fe-based materials. By using femtosecond time- and angle-resolved photoelectron spectroscopy, we study phonon frequencies in ultrathin FeSe/SrTiO3 films grown by molecular beam epitaxy. After optical excitation, we observe periodic modulations of the photoelectron spectrum as a function of pump–probe delay for 1-unit-cell, 3-unit-cell, and 60-unit-cell thick FeSe films. The frequencies of the coherent intensity oscillations increase from 5.00 ± 0.02 to 5.25 ± 0.02 THz with increasing film thickness. By comparing with previous works, we attribute this mode to the Se A1g phonon. The dominant mechanism for the phonon softening in 1-unit-cell thick FeSe films is a substrate-induced lattice strain. Results demonstrate an abrupt phonon renormalization due to a lattice mismatch between the ultrathin film and the substrate.

  9. Broadband Reflectionless Metasheets: Frequency-Selective Transmission and Perfect Absorption

    Directory of Open Access Journals (Sweden)

    V. S. Asadchy

    2015-07-01

    Full Text Available Energy of propagating electromagnetic waves can be fully absorbed in a thin lossy layer, but only in a narrow frequency band, as follows from the causality principle. On the other hand, it appears that there are no fundamental limitations on broadband matching of thin resonant absorbing layers. However, known thin absorbers produce significant reflections outside of the resonant absorption band. In this paper, we explore possibilities to realize a thin absorbing layer that produces no reflected waves in a very wide frequency range, while the transmission coefficient has a narrow peak of full absorption. Here we show, both theoretically and experimentally, that a thin resonant absorber, invisible in reflection in a very wide frequency range, can be realized if one and the same resonant mode of the absorbing array unit cells is utilized to create both electric and magnetic responses. We test this concept using chiral particles in each unit cell, arranged in a periodic planar racemic array, utilizing chirality coupling in each unit cell but compensating the field coupling at the macroscopic level. We prove that the concept and the proposed realization approach also can be used to create nonreflecting layers for full control of transmitted fields. Our results can have a broad range of potential applications over the entire electromagnetic spectrum including, for example, perfect ultracompact wave filters and selective multifrequency sensors.

  10. Multi-frequency Defect Selective Imaging via Nonlinear Ultrasound

    Science.gov (United States)

    Solodov, Igor; Busse, Gerd

    The concept of defect-selective ultrasonic nonlinear imaging is based on visualization of strongly nonlinear inclusions in the form of localized cracked defects. For intense excitation, the ultrasonic response of defects is affected by mechanical constraint between their fragments that makes their vibrations extremely nonlinear. The cracked flaws, therefore, efficiently generate multiple new frequencies, which can be used as a nonlinear "tag" to detect and image them. In this paper, the methodologies of nonlinear scanning laser vibrometry (NSLV) and nonlinear air-coupled emission (NACE) are applied for nonlinear imaging of various defects in hi-tech and constructional materials. A broad database obtained demonstrates evident advantages of the nonlinear approach over its linear counterpart. The higher-order nonlinear frequencies provide increase in signal-to-noise ratio and enhance the contrast of imaging. Unlike conventional ultrasonic instruments, the nonlinear approach yields abundant multi-frequency information on defect location. The application of image recognition and processing algorithms is described and shown to improve reliability and quality of ultrasonic imaging.

  11. Effect of efferent activation on binaural frequency selectivity.

    Science.gov (United States)

    Verhey, Jesko L; Kordus, Monika; Drga, Vit; Yasin, Ifat

    2017-07-01

    Binaural notched-noise experiments indicate a reduced frequency selectivity of the binaural system compared to monaural processing. The present study investigates how auditory efferent activation (via the medial olivocochlear system) affects binaural frequency selectivity in normal-hearing listeners. Thresholds were measured for a 1-kHz signal embedded in a diotic notched-noise masker for various notch widths. The signal was either presented in phase (diotic) or in antiphase (dichotic), gated with the noise. Stimulus duration was 25 ms, in order to avoid efferent activation due to the masker or the signal. A bandpass-filtered noise precursor was presented prior to the masker and signal stimuli to activate the efferent system. The silent interval between the precursor and the masker-signal complex was 50 ms. For comparison, thresholds for detectability of the masked signal were also measured in a baseline condition without the precursor and, in addition, without the masker. On average, the results of the baseline condition indicate an effectively wider binaural filter, as expected. For both signal phases, the addition of the precursor results in effectively wider filters, which is in agreement with the hypothesis that cochlear gain is reduced due to the presence of the precursor. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. A quantitative study of ramped radio frequency, magnetization transfer, and slab thickness in three-dimensional time-of-flight magnetic resonance angiography in a patient population.

    Science.gov (United States)

    Goodrich, K C; Blatter, D D; Parker, D L; Du, Y P; Meyer, K J; Bernstein, M A

    1996-06-01

    The authors compare the effectiveness of various magnetic resonance (MR) angiography acquisition strategies in enhancing the visibility of small intracranial vessels. Blood vessel contrast-to-noise ratio (CNR) in time-of-flight MR angiography was studied as a function of vessel size and several selectable imaging parameters. Contrast-to-noise measurements were made on 257 vessel segments ranging in size from 0.3 mm to 4.2 mm in patients who recently had undergone intraarterial cerebral angiography. Imaging parameters studied included magnetization transfer, spatially variable radio frequency (RF) pulse profile (ramped RF), and imaging slab thickness. The combination of thin slabs (16 slices/slab), ramped RF, and magnetization transfer resulted in the highest CNR for all but the smallest vessel sizes. The smallest vessels (slab (64 slices/slab) with ramped RF and magnetization transfer. Magnetization transfer always improved vessel CNR, but the improvement diminished as the slab thickness was reduced. The CNR increased with a decrease in slab thickness for all but the smallest vessel sizes. Overall, the results provide a quantitative demonstration that inflow enhancement of blood is reduced for small vessels. Thus, whereas magnetization transfer is important at all vessel sizes, it becomes the primary factor in improving the visibility of the smallest vessels.

  13. Research on High Layer Thickness Fabricated of 316L by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Shuo Wang

    2017-09-01

    Full Text Available Selective laser melting (SLM is a potential additive manufacturing (AM technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 μs-40 μm-240 μm. Also, the building rate can be up to 12 mm3/s, which is about 3–10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 μs to 200 μs, the grain size is gradually grown up from 0.98 μm to 2.23 μm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.

  14. Research on High Layer Thickness Fabricated of 316L by Selective Laser Melting.

    Science.gov (United States)

    Wang, Shuo; Liu, Yude; Shi, Wentian; Qi, Bin; Yang, Jin; Zhang, Feifei; Han, Dong; Ma, Yingyi

    2017-09-08

    Selective laser melting (SLM) is a potential additive manufacturing (AM) technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 μs-40 μm-240 μm. Also, the building rate can be up to 12 mm³/s, which is about 3-10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 μs to 200 μs, the grain size is gradually grown up from 0.98 μm to 2.23 μm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.

  15. Nanoparticle array based optical frequency selective surfaces: theory and design.

    Science.gov (United States)

    Saeidi, Chiya; van der Weide, Daniel

    2013-07-01

    We demonstrate a synthesis procedure for designing a bandstop optical frequency selective surface (FSS) composed of nanoparticle (NP) elements. The proposed FSS uses two-dimensional (2-D) periodic arrays of NPs with subwavelength unit-cell dimensions. We derive equivalent circuit for a nanoparticle array (NPA) using the closed-form solution for a 2-D NPA excited by a plane wave in the limit of the dipole approximation, which includes contribution from both individual and collective plasmon modes. Using the extracted equivalent circuit, we demonstrate synthesis of an optical FSS using cascaded NPA layers as coupled resonators, which we validate with both circuit model and full-wave simulation for a third-order Butterworth bandstop prototype.

  16. Frequency selective surfaces based high performance microstrip antenna

    CERN Document Server

    Narayan, Shiv; Jha, Rakesh Mohan

    2016-01-01

    This book focuses on performance enhancement of printed antennas using frequency selective surfaces (FSS) technology. The growing demand of stealth technology in strategic areas requires high-performance low-RCS (radar cross section) antennas. Such requirements may be accomplished by incorporating FSS into the antenna structure either in its ground plane or as the superstrate, due to the filter characteristics of FSS structure. In view of this, a novel approach based on FSS technology is presented in this book to enhance the performance of printed antennas including out-of-band structural RCS reduction. In this endeavor, the EM design of microstrip patch antennas (MPA) loaded with FSS-based (i) high impedance surface (HIS) ground plane, and (ii) the superstrates are discussed in detail. The EM analysis of proposed FSS-based antenna structures have been carried out using transmission line analogy, in combination with the reciprocity theorem. Further, various types of novel FSS structures are considered in desi...

  17. Tunable antenna radome based on graphene frequency selective surface

    Science.gov (United States)

    Qu, Meijun; Rao, Menglou; Li, Shufang; Deng, Li

    2017-09-01

    In this paper, a graphene-based frequency selective surface (FSS) is proposed. The proposed FSS exhibits a tunable bandpass filtering characteristic due to the alterable conductivity of the graphene strips which is controlled by chemical potential. Based on the reconfigurable bandpass property of the proposed FSS, a cylindrical antenna radome is designed using the FSS unit cells. A conventional omnidirectional dipole can realize a two-beam directional pattern when it is placed into the proposed antenna radome. Forward and backward endfire radiations of the dipole loaded with the radome is realized by properly adjusting the chemical potential. The proposed antenna radome is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems when the gain of a conventional antenna needs to be enhanced.

  18. Relationships among cloud occurrence frequency, overlap, and effective thickness derived from CALIPSO and CloudSat merged cloud vertical profiles

    Science.gov (United States)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2010-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profiles derived from the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and cloud profiling radar. The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical profiles can be related by a cloud overlap matrix when the correlation length of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches random overlap with increasing distance separating cloud layers and that the probability of deviating from random overlap decreases exponentially with distance. One month of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat data (July 2006) support these assumptions, although the correlation length sometimes increases with separation distance when the cloud top height is large. The data also show that the correlation length depends on cloud top hight and the maximum occurs when the cloud top height is 8 to 10 km. The cloud correlation length is equivalent to the decorrelation distance introduced by Hogan and Illingworth (2000) when cloud fractions of both layers in a two-cloud layer system are the same. The simple relationships derived in this study can be used to estimate the top-of-atmosphere irradiance difference caused by cloud fraction, uppermost cloud top, and cloud thickness vertical profile differences.

  19. Dual-band frequency selective surface with large band separation and stable performance

    Science.gov (United States)

    Zhou, Hang; Qu, Shao-Bo; Peng, Wei-Dong; Lin, Bao-Qin; Wang, Jia-Fu; Ma, Hua; Zhang, Jie-Qiu; Bai, Peng; Wang, Xu-Hua; Xu, Zhuo

    2012-05-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations.

  20. A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

    Science.gov (United States)

    Majidzadeh, Maryam; Ghobadi, Changiz; Nourinia, Javad

    2017-03-01

    A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm2 FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes' 'ON' state provides rejection of 2.4 GHz WLAN in 2-3 GHz, 5.2/5.8 GHz WLAN and X band in 5-12 GHz, and a part of Ku band in 13.9-16 GHz. In diodes 'OFF' state, the FSS blocks WLAN in 4-7.3 GHz, X band in 8-12.7 GHz as well as part of Ku band in 13.7-16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.

  1. Type-I frequency-doubling characteristics of high-power, ultrafast fiber laser in thick BIBO crystal.

    Science.gov (United States)

    Chaitanya N, Apurv; Aadhi, A; Singh, R P; Samanta, G K

    2014-09-15

    We report on experimental realization of optimum focusing condition for type-I second-harmonic generation (SHG) of high-power, ultrafast laser in "thick" nonlinear crystal. Using single-pass, frequency doubling of a 5 W Yb-fiber laser of pulse width ~260 fs at repetition rate of 78 MHz in a 5-mm-long bismuth triborate (BIBO) crystal we observed that the optimum focusing condition is more dependent on the birefringence of the crystal than its group-velocity mismatch (GVM). A theoretical fit to our experimental results reveals that even in the presence of GVM, the optimum focusing condition matches the theoretical model of Boyd and Kleinman, predicted for continuous-wave and long-pulse SHG. Using a focusing factor of ξ=1.16 close to the estimated optimum value of ξ=1.72 for our experimental conditions, we generated 2.25 W of green radiation of pulse width 176 fs with single-pass conversion efficiency as high as 46.5%. Our study also verifies the effect of pulse narrowing and broadening of angular phase-matching bandwidth of SHG at tighter focusing. This study signifies the advantage of SHG in "thick" crystal in controlling SH-pulse width by changing the focusing lens while accessing high conversion efficiency and broad angular phase-matching bandwidth.

  2. The short-term effects of antenna insulation thickness on path losses in wireless telemetry implants at microwave frequencies

    Directory of Open Access Journals (Sweden)

    Lukas Kneisz

    2013-07-01

    Full Text Available Various physiological parameters can be monitored non-invasively using wireless biotelemetry links. The development of sophisticated ultra low power consuming transceivers allows the transmission of large amounts of data from the inside of the body to an external receiver in real time at microwave frequencies.Antenna impedance matching is crucial for obtaining an acceptable propagation link budget in a wireless telemetry link. The dielectric properties of biological tissue induce detuning to transceiver antennas when implanted into the body. To counteract detuning problems, implant antennas are coated with biocompatible insulating material. The study investigates the propagation losses of a wireless communication link at different insulation thicknesses of medical grade silicone in the Industrial-Scientific-Medical (ISM radio band at 2.45 GHz. The wireless link consisted of an implantable unit which was placed between two pads of tissue substitute material and an external receiver which was connected to a laptop. Predefined data packets were transmitted from the implant, the received packets were analyzed, packet errors and packet losses were logged and the received signal strength indicator values (RSSI were recorded. Our results showed that the mean RSSI values of insulated transmitter antennas - embedded in tissue equivalent material - provide more safety distance to critical receiver sensitivity level than uncoated antennas.The conducted measurements let us conclude that with increasing thickness of the insulation layer, the antenna becomes less sensitive to detuning by adjacent tissue substitute material. Therefore tuned antennas are less influenced by the surrounding tissue after implantation.

  3. [Clinical auxiliary diagnosis value of high frequency ultrasonographic measurements of the thickness of transverse carpal ligaments in carpal tunnel syndrome patients].

    Science.gov (United States)

    Xu, L; Chen, F M; Wang, L; Zhang, P X; Jiang, X R

    2016-04-18

    To evaluate the meaning and value of high-frequency ultrasound in the diagnosis of carpal tunnel syndrome (CTS). In this study, 48 patients (unilateral hand) with CTS were analyzed. The thickness of transverse carpal ligaments at the pisiform bone was measured using high-frequency ultrasound. Open carpal tunnel release procedure was performed in the 48 CTS patients, and the thickness of transverse carpal ligaments at the hamate hook bone measured using vernier caliper under direct vision. The accuracy of thickness of transverse carpal ligaments was evaluated using high-frequency ultrasound. high-frequency ultrasound measurement of thickness of transverse carpal ligaments at the hamate hook bone and pisiform bone, and determination of the diagnostic threshold measurement index using receiver operating characteristic (ROC) curve, sensitivity and specificity were performed and the correlation between the thickness of transverse carpal ligaments and nerve conduction study (NCS) analyzed. The thickness of transverse carpal ligaments in the CTS patients were (0.42±0.08) cm (high-frequency ultrasound) and (0.41±0.06) cm (operation) at hamate hook bone, and there was no significant difference between the two ways (t=0.672, P>0.05). The optimal cut-off value of the transverse carpal ligaments at hamate hook bone was 0.385 cm, the sensitivity 0.775, and the specificity 0.788. The optimal cut-off value of the transverse carpal ligaments at the pisiform bone was 0.315 cm, the sensitivity 0.950, and the specificity 1.000. The transverse carpal ligaments thickness and wrist-index finger sensory nerve conduction velocity (SCV), wrist-middle finger SCV showed a negative correlation. High frequency ultrasound measurements of thickness of transverse carpal ligaments is a valuable method for the diagnosis of CTS.

  4. Relation of Cloud Occurrence Frequency, Overlap, and Effective Thickness Derived from CALIPSO and CloudSat Merged Cloud Vertical Profiles

    Science.gov (United States)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2009-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profile derived from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR). The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical pro les can be related by a set of equations when the correlation distance of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches the random overlap with increasing distance separating cloud layers and that the probability of deviating from the random overlap decreases exponentially with distance. One month of CALIPSO and CloudSat data support these assumptions. However, the correlation distance sometimes becomes large, which might be an indication of precipitation. The cloud correlation distance is equivalent to the de-correlation distance introduced by Hogan and Illingworth [2000] when cloud fractions of both layers in a two-cloud layer system are the same.

  5. Removal of Optically Thick Clouds from Multi-Spectral Satellite Images Using Multi-Frequency SAR Data

    Directory of Open Access Journals (Sweden)

    Robert Eckardt

    2013-06-01

    Full Text Available This study presents a method for the reconstruction of pixels contaminated by optical thick clouds in multi-spectral Landsat images using multi-frequency SAR data. A number of reconstruction techniques have already been proposed in the scientific literature. However, all of the existing techniques have certain limitations. In order to overcome these limitations, we expose the Closest Spectral Fit (CSF method proposed by Meng et al. to a new, synergistic approach using optical and SAR data. Therefore, the term Closest Feature Vector (CFV is introduced. The technique facilitates an elegant way to avoid radiometric distortions in the course of image reconstruction. Furthermore the cloud cover removal is independent from underlying land cover types and assumptions on seasonality, etc. The methodology is applied to mono-temporal, multi-frequency SAR data from TerraSAR-X (X-Band, ERS (C-Band and ALOS Palsar (L-Band. This represents a way of thinking about Radar data not as foreign, but as additional data source in multi-spectral remote sensing. For the assessment of the image restoration performance, an experimental framework is established and a statistical evaluation protocol is designed. The results show the potential of a synergistic usage of multi-spectral and SAR data to overcome the loss of data due to cloud cover.

  6. Substrate integrated ferrite phase shifters and active frequency selective surfaces

    International Nuclear Information System (INIS)

    Cahill, B.M.

    2002-01-01

    There are two distinct parts to this thesis; the first investigates the use of ferrite tiles in the construction of printed phase shifting transmission lines, culminating in the design of two compact electromagnetic controlled beam steered patch and slot antenna arrays. The second part investigates the use of active frequency selective surfaces (AFSS), which are later used to cover a uPVC constructed enclosure. Field intensity measurements are taken from within the enclosure to determine the dynamic screening effectiveness. Trans Tech G-350 Ferrite is investigated to determine its application in printed microstrip and stripline phase shifting transmission lines. 50-Ohm transmission lines are constructed using the ferrite tile and interfaced to Rogers RT Duroid 5870 substrate. Scattering parameter measurements are made under the application of variable magnetic fields to the ferrite. Later, two types of planar microwave beam steering antennas are constructed. The first uses the ferrites integrated into the Duroid as microstrip lines with 3 patch antennas as the radiating elements. The second uses stripline transmission lines, with slot antennas as the radiating sources etched into the ground plane of the triplate. Beam steering is achieved by the application of an external electromagnet. An AFSS is constructed by the interposition of PIN diodes into a dipole FSS array. Transmission response measurements are then made for various angles of electromagnetic wave incidence. Two states of operation exist: when a current is passed through the diodes and when the diodes are switched off. These two states form a high pass and band stop space filter respectively. An enclosure covered with the AFSS is constructed and externally illuminated in the range 2.0 - 2.8GHz. A probe antenna inside the enclosure positioned at various locations through out the volume is used to establish the effective screening action of the AFSS in 3 dimensional space. (author)

  7. Optical Transmitter Terminal for Selective RF High Frequency Bans

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent improvements in multiplexing systems and tunable laser semiconductor diodes make the use of Wavelength Division Multiplexing to combine multiple frequency...

  8. Assessing the copula selection for bivariate frequency analysis ...

    Indian Academy of Sciences (India)

    58

    Copulas are applied to overcome the restriction of traditional bivariate frequency ... frequency analysis methods cannot describe the random variable properties that ... In order to overcome the limitation of multivariate distributions, a copula is a ..... The Mann-Kendall (M-K) test is a non-parametric statistical test which is used ...

  9. How Metastrategic Considerations Influence the Selection of Frequency Estimation Strategies

    Science.gov (United States)

    Brown, Norman R.

    2008-01-01

    Prior research indicates that enumeration-based frequency estimation strategies become increasingly common as memory for relevant event instances improves and that moderate levels of context memory are associated with moderate rates of enumeration [Brown, N. R. (1995). Estimation strategies and the judgment of event frequency. Journal of…

  10. Spatial Tuning of a RF Frequency Selective Surface through Origami (Postprint)

    Science.gov (United States)

    2016-05-12

    computational tools to systematically predict optimal folds. 15. SUBJECT TERMS origami, frequency selective surface, tuning, radio frequency 16...experimental study and motivates the development of computational tools to systematically predict optimal fold patterns for targeted frequency response...folding motions. The precise mapping of origami presents a novel method to spatially tune radio frequency (RF) devices, including adaptive antennas

  11. Improving accuracy of overhanging structures for selective laser melting through reliability characterization of single track formation on thick powder beds

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2016-01-01

    Repeatability and reproducibility of parts produced by selective laser melting is a standing issue, and coupled with a lack of standardized quality control presents a major hindrance towards maturing of selective laser melting as an industrial scale process. Consequently, numerical process...... modelling has been adopted towards improving the predictability of the outputs from the selective laser melting process. Establishing the reliability of the process, however, is still a challenge, especially in components having overhanging structures.In this paper, a systematic approach towards...... establishing reliability of overhanging structure production by selective laser melting has been adopted. A calibrated, fast, multiscale thermal model is used to simulate the single track formation on a thick powder bed. Single tracks are manufactured on a thick powder bed using same processing parameters...

  12. Theoretical study of the influence of twine thickness on haddock selectivity in diamond mesh cod-ends

    DEFF Research Database (Denmark)

    Herrmann, Bent; O'Neill, F.G.

    2006-01-01

    Using the cod-end simulation model PRESEMO, the influence of twine thickness on cod-end selectivity is investigated. The reduction of lateral mesh opening that arises as a result of both twine bending stiffness and the physical presence of the twine is considered. While it is shown that this lead...

  13. Correlation between coronary artery disease severity, left ventricular mass index and carotid intima media thickness, assessed by radio-frequency

    Directory of Open Access Journals (Sweden)

    Ciccone Marco M

    2011-11-01

    Full Text Available Abstract Background Intima-media thickness of the common carotid artery (CCA-IMT is a validated marker of systemic atherosclerosis process. The aim of this study was to evaluate the association between coronary artery disease (CAD, left ventricular hypertrophy (LVH and CCA-IMT, assessed by Radio Frequency-Quality Intima Media Thickness (RFQIMT method, the next generation of IMT real-time measurement, based on the direct analysis of the radiofrequency signal and endowed with high accuracy and reproducibility in early detection of arterial wall thickness. Methods 115 patients (76 men, mean age: 65.1 ± 12 years referred to our department and shown significant (≥ 70% luminal obstruction stenosis at least in one major epicardial coronary artery were studied. Coronary angiograms were divided for severity and extent of the disease: 79 patients (69% had one, 24 patients (21% two, 12 patients (10% three major epicardial coronary arteries with ≥ 70% stenosis. All patients underwent echocardiography and carotid ultrasound examination, assessed by RF. Results Dividing RFQIMT data in tertiles, dyslipidaemia (31 patients with IMT ≥ 1.20 mm vs 16 with IMT = 0.91-1.19 vs 25 with IMT ≤ 0.9, p = 0.004, LVMI (153.5 ± 20.6 g/m2 in IMT ≥ 1.20 mm vs 131.2 ± 8.4 g/m2 in IMT = 0.91-1.19 mm vs 114.3 ± 11.1 g/m2 in IMT ≤ 0.9 mm, P 2 = 0.88, RFQIMT remained significantly associated with the dyslipidemia (regression coefficient ± standard error [SE]: 0.057 ± 0.023; p = 0.017, LVMI (regression coefficient ± SE: 0.01 ± 0.001; P Conclusions RFQIMT is a sophisticated method for carotid ultrasound evaluation. Its evaluation in patients with at least one important major epicardial coronary vessel stenosis would help the accuracy in the general assessment of the number of coronary lesions in these patients.

  14. Application of high Tc superconductors as frequency selective surfaces: Experiment and theory

    International Nuclear Information System (INIS)

    Dawei Zhang; Yahya Rahmat-Samii; Fetterman, H.R.

    1993-01-01

    YBa 2 Cu 3 O 7-x and Tl 2 CaBa 2 Cu 2 O 8 high temperature superconducting thin films were utilized to fabricate frequency selective surfaces (FSS) at millimeter-wave frequencies (75--110 GHz). An analytical/numerical model was applied, using a Floquet expansion and the Method of Moments, to analyze bandstop superconducting frequency selective surfaces. Experimental results were compared with the model, and showed a good agreement with resonant frequency prediction with an accuracy of better than 1%. The use of the superconducting frequency selective surfaces as quasi-optical millimeter-wave bandpass filters was also demonstrated

  15. The research of characteristic difference of selected frequency luminescence for desert sand

    International Nuclear Information System (INIS)

    Liu Chao; Wei Mingjian; Li Huhou

    2011-01-01

    The characters of selected frequency luminescence of four groups of samples from Badain Jaran desert are measured by BG2003 luminescence spectrograph. The measurement subjects include selected frequency optical stimulate luminescence spectrum, selected frequency thermoluminescence spectrum and the dose response curve. A double-peak map is obtained by the result from all groups of data and spectrum. The difference is emerged between each group. The optical stimulate luminescence and thermoluminescence is applied in the measurement process. The dispersion of photon count on every response wavelength is analyzed. Based on the analysis, a better result can be gained by selected frequency thermoluminescence. (authors)

  16. Optimal stapler cartridge selection according to the thickness of the pancreas in distal pancreatectomy.

    Science.gov (United States)

    Kim, Hongbeom; Jang, Jin-Young; Son, Donghee; Lee, Seungyeoun; Han, Youngmin; Shin, Yong Chan; Kim, Jae Ri; Kwon, Wooil; Kim, Sun-Whe

    2016-08-01

    Stapling is a popular method for stump closure in distal pancreatectomy (DP). However, research on which cartridges are suitable for different pancreatic thickness is lacking. To identify the optimal stapler cartridge choice in DP according to pancreatic thickness.From November 2011 to April 2015, data were prospectively collected from 217 consecutive patients who underwent DP with 3-layer endoscopic staple closure in Seoul National University Hospital, Korea. Postoperative pancreatic fistula (POPF) was graded according to International Study Group on Pancreatic Fistula definitions. Staplers were grouped based on closed length (CL) (Group I: CL ≤ 1.5 mm, II: 1.5 mm 17 mm. With pancreatic thickness <12 mm, the POPF rate was lowest with Group II (I: 50%, II: 27.6%, III: 69.2%, P = 0.035).The optimal stapler cartridges with pancreatic thickness <12 mm were those in Group II (Gold, CL: 1.8 mm). There was no suitable cartridge for thicker pancreases. Further studies are necessary to reduce POPF in thick pancreases.

  17. Optimized thick-wall cylinders by virtue of Poisson's ratio selection

    International Nuclear Information System (INIS)

    Whitty, J.P.M.; Henderson, B.; Francis, J.; Lloyd, N.

    2011-01-01

    The principal stress distributions in thick-wall cylinders due to variation in the Poisson's ratio are predicted using analytical and finite element methods. Analyses of appropriate brittle and ductile failure criteria show that under the isochoric pressure conditions investigated that auextic (i.e. those possessing a negative Poisson's ratio) materials act as stress concentrators; hence they are predicted to fail before their conventional (i.e. possessing a positive Poisson's ratio) material counterparts. The key finding of the work presented shows that for constrained thick-wall cylinders the maximum tensile principal stress can vanish at a particular Poisson's ratio and aspect ratio. This phenomenon is exploited in order to present an optimized design criterion for thick-wall cylinders. Moreover, via the use of a cogent finite element model, this criterion is also shown to be applicable for the design of micro-porous materials.

  18. Creaming enhancement in a liter scale ultrasonic reactor at selected transducer configurations and frequencies.

    Science.gov (United States)

    Juliano, Pablo; Temmel, Sandra; Rout, Manoj; Swiergon, Piotr; Mawson, Raymond; Knoerzer, Kai

    2013-01-01

    Recent research has shown that high frequency ultrasound (0.4-3 MHz), can enhance milkfat separation in small scale systems able to treat only a few milliliters of sample. In this work, the effect of ultrasonic standing waves on milkfat creaming was studied in a 6L reactor and the influence of different frequencies and transducer configurations in direct contact with the fluid was investigated. A recombined coarse milk emulsion with fat globules stained with oil-red-O dye was selected for the separation trials. Runs were performed with one or two transducers placed in vertical (parallel or perpendicular) and horizontal positions (at the reactor base) at 0.4, 1 and/or 2 MHz (specific energy 8.5 ± 0.6 kJ/kg per transducer). Creaming behavior was assessed by measuring the thickness of the separated cream layer. Other methods supporting this assessment included the measurement of fat content, backscattering, particle size distribution, and microscopy of samples taken at the bottom and top of the reactor. Most efficient creaming was found after treatment at 0.4 MHz in single and double vertical transducer configurations. Among these configurations, a higher separation rate was obtained when sonicating at 0.4 MHz in a vertical perpendicular double transducer setup. The horizontal transducer configuration promoted creaming at 2 MHz only. Fat globule size increase was observed when creaming occurred. This research highlights the potential for enhanced separation of milkfat in larger scale systems from selected transducer configurations in contact with a dairy emulsion, or emulsion splitting in general. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Model validity and frequency band selection in operational modal analysis

    Science.gov (United States)

    Au, Siu-Kui

    2016-12-01

    Experimental modal analysis aims at identifying the modal properties (e.g., natural frequencies, damping ratios, mode shapes) of a structure using vibration measurements. Two basic questions are encountered when operating in the frequency domain: Is there a mode near a particular frequency? If so, how much spectral data near the frequency can be included for modal identification without incurring significant modeling error? For data with high signal-to-noise (s/n) ratios these questions can be addressed using empirical tools such as singular value spectrum. Otherwise they are generally open and can be challenging, e.g., for modes with low s/n ratios or close modes. In this work these questions are addressed using a Bayesian approach. The focus is on operational modal analysis, i.e., with 'output-only' ambient data, where identification uncertainty and modeling error can be significant and their control is most demanding. The approach leads to 'evidence ratios' quantifying the relative plausibility of competing sets of modeling assumptions. The latter involves modeling the 'what-if-not' situation, which is non-trivial but is resolved by systematic consideration of alternative models and using maximum entropy principle. Synthetic and field data are considered to investigate the behavior of evidence ratios and how they should be interpreted in practical applications.

  20. Dual-band frequency selective surface with large band separation and stable performance

    International Nuclear Information System (INIS)

    Zhou Hang; Qu Shao-Bo; Lin Bao-Qin; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Peng Wei-Dong; Bai Peng; Wang Xu-Hua; Xu Zhuo

    2012-01-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. Enhanced selectivity of boron doped diamond electrodes for the detection of dopamine and ascorbic acid by increasing the film thickness

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yao; Long, Hangyu [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Ma, Li, E-mail: marycsupm@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wei, Quiping, E-mail: qiupwei@csu.edu.cn [School of Material Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Li, Site [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Yu, Zhiming [School of Material Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Hu, Jingyuan [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Liu, Peizhi [Key laboratory of interface science and engineering in advanced materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024,PR China (China); Wang, Yijia [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Meng, Lingcong [Department of Chemistry, University of Warwick, Coventry, West Midlands CV4 7AL (United Kingdom)

    2016-12-30

    Highlights: • BDD electrodes with different thickness have been fabricated. • BDD electrodes are used for simultaneous detection of DA and AA. • Anodic pretreatment enhance the separation of DA and AA oxidation peak potential. • Thicker BDD electrode show better performance for DA detection coexisting with AA. - Abstract: In this paper, boron doped diamond (BDD) with different thickness were prepared by hot filament chemical vapor deposition. The performance of BDD electrodes for detecting dopamine (DA) and ascorbic acid (AA) were investigated. Scanning electron microscopy and Raman spectra reveal the grain size increases and the film quality improves with the increase of film thickness. Electrochemical test show that the transfer coefficient in [Fe{sub 3} (CN) {sub 6}]{sup 3−/4−} redox system increases with the increase of the film thickness. The results of selectivity and sensitivity for DA mixed with AA detection show that 8h-BDD and 12h-BDD electrodes possess well selective separated oxidation peaks of DA and AA, and the 12h-BDD electrode exhibits optimal sensitivity until the DA concentration drops to 1 μ M.

  2. Robust and efficient multi-frequency temporal phase unwrapping: optimal fringe frequency and pattern sequence selection.

    Science.gov (United States)

    Zhang, Minliang; Chen, Qian; Tao, Tianyang; Feng, Shijie; Hu, Yan; Li, Hui; Zuo, Chao

    2017-08-21

    Temporal phase unwrapping (TPU) is an essential algorithm in fringe projection profilometry (FPP), especially when measuring complex objects with discontinuities and isolated surfaces. Among others, the multi-frequency TPU has been proven to be the most reliable algorithm in the presence of noise. For a practical FPP system, in order to achieve an accurate, efficient, and reliable measurement, one needs to make wise choices about three key experimental parameters: the highest fringe frequency, the phase-shifting steps, and the fringe pattern sequence. However, there was very little research on how to optimize these parameters quantitatively, especially considering all three aspects from a theoretical and analytical perspective simultaneously. In this work, we propose a new scheme to determine simultaneously the optimal fringe frequency, phase-shifting steps and pattern sequence under multi-frequency TPU, robustly achieving high accuracy measurement by a minimum number of fringe frames. Firstly, noise models regarding phase-shifting algorithms as well as 3-D coordinates are established under a projector defocusing condition, which leads to the optimal highest fringe frequency for a FPP system. Then, a new concept termed frequency-to-frame ratio (FFR) that evaluates the magnitude of the contribution of each frame for TPU is defined, on which an optimal phase-shifting combination scheme is proposed. Finally, a judgment criterion is established, which can be used to judge whether the ratio between adjacent fringe frequencies is conducive to stably and efficiently unwrapping the phase. The proposed method provides a simple and effective theoretical framework to improve the accuracy, efficiency, and robustness of a practical FPP system in actual measurement conditions. The correctness of the derived models as well as the validity of the proposed schemes have been verified through extensive simulations and experiments. Based on a normal monocular 3-D FPP hardware system

  3. Frequency-dependent selection predicts patterns of radiations and biodiversity

    NARCIS (Netherlands)

    Melian, Carlos J.; Alonso, David; Vazquez, Diego P.; Regetz, James; Allesina, Stefano

    2010-01-01

    Most empirical studies support a decline in speciation rates through time, although evidence for constant speciation rates also exists. Declining rates have been explained by invoking pre-existing niches, whereas constant rates have been attributed to non-adaptive processes such as sexual selection

  4. Does modifying the thick texture and creamy flavour of a drink change portion size selection and intake?

    Science.gov (United States)

    McCrickerd, Keri; Chambers, Lucy; Yeomans, Martin R

    2014-02-01

    Previous research indicates that a drink's sensory characteristics can influence appetite regulation. Enhancing the thick and creamy sensory characteristics of a drink generated expectations of satiety and improved its actual satiating effects. Expectations about food also play an important role in decisions about intake, in which case enhancing the thick and creamy characteristics of a drink might also result in smaller portion size selection. In the current study forty-eight participants (24 female) completed four test days where they came into the laboratory for a fixed-portion breakfast, returning two hours later for a mid-morning drink, which they could serve themselves and consume as much as they liked. Over the test days, participants consumed an iso-energetic drink in four sensory contexts: thin and low-creamy; thin and high-creamy; thick and low-creamy; thick and high-creamy. Results indicated that participants consumed less of the thick drinks, but that this was only true of the female participants; male participants consumed the same amount of the four drinks regardless of sensory context. The addition of creamy flavour did not affect intake but the thicker drinks were associated with an increase in perceived creaminess. Despite differences in intake, hunger and fullness ratings did not differ across male and female participants and were not affected by the drinks sensory characteristics. The vast majority of participants consumed all of the drink they served themselves indicating that differences in intake reflected portion size decisions. These findings suggest women will select smaller portions of a drink when its sensory characteristics indicate that it will be satiating. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Noise-based frequency offset modulation in wideband frequency-selective fading channels

    NARCIS (Netherlands)

    Meijerink, Arjan; Cotton, S.L.; Bentum, Marinus Jan; Scanlon, W.G.

    2009-01-01

    A frequency offset modulation scheme using wideband noise carriers is considered. The main advantage of such a scheme is that it enables fast receiver synchronization without channel adaptation, while providing robustness to multipath fading and in-band interference. This is important for low-power

  6. Use of high-frequency ultrasonography for evaluation of skin thickness in relation to hydration status and fluid distribution at various cutaneous sites in dogs.

    Science.gov (United States)

    Diana, Alessia; Guglielmini, Carlo; Fracassi, Federico; Pietra, Marco; Balletti, Erika; Cipone, Mario

    2008-09-01

    To assess the usefulness of high-frequency diagnostic ultrasonography for evaluation of changes of skin thickness in relation to hydration status and fluid distribution at various cutaneous sites in dogs. 10 clinically normal adult dogs (6 males and 4 females) of various breeds. Ultrasonographic examination of the skin was performed before and after hydration via IV administration of an isotonic crystalloid solution (30 mL/kg/h for 30 minutes). A 13-MHz linear-array transducer was used to obtain series of ultrasonographic images at 4 different cutaneous sites (the frontal, sacral, flank, and metatarsal regions). Weight and various clinicopathologic variables (PCV; serum osmolality; and serum total protein, albumin, and sodium concentrations) were determined before and after the infusion. These variables and ultrasonographic measurements of skin thickness before and after hydration were compared. Among the 10 dogs, mean preinfusion skin thickness ranged from 2,211 microm (metatarsal region) to 3,249 microm (sacral region). Compared with preinfusion values, weight was significantly increased, whereas PCV; serum osmolality; and serum total protein, albumin, and sodium concentrations were significantly decreased after infusion. After infusion, dermal echogenicity decreased and skin thickness increased significantly by 21%, 14%, 15%, and 13% in the frontal, sacral, flank, and metatarsal regions, respectively. Cutaneous site and hydration were correlated with cutaneous characteristics and skin thickness determined by use of high-frequency ultrasonography in dogs. Thus, diagnostic ultrasonography may be a useful tool for the noninvasive evaluation of skin hydration in healthy dogs and in dogs with skin edema.

  7. Use of apparent thickness for preprocessing of low-frequency electromagnetic data in inversion-based multibarrier evaluation workflow

    Science.gov (United States)

    Omar, Saad; Omeragic, Dzevat

    2018-04-01

    The concept of apparent thicknesses is introduced for the inversion-based, multicasing evaluation interpretation workflow using multifrequency and multispacing electromagnetic measurements. A thickness value is assigned to each measurement, enabling the development of two new preprocessing algorithms to remove casing collar artifacts. First, long-spacing apparent thicknesses are used to remove, from the pipe sections, artifacts ("ghosts") caused by the transmitter crossing a casing collar or corrosion. Second, a collar identification, localization, and assignment algorithm is developed to enable robust inversion in collar sections. Last, casing eccentering can also be identified on the basis of opposite deviation of short-spacing phase and magnitude apparent thicknesses from the nominal value. The proposed workflow can handle an arbitrary number of nested casings and has been validated on synthetic and field data.

  8. Ecological genetics of the Bromus tectorum (Poaceae) - Ustilago Bullata (Ustilaginaceae): A role for frequency dependent selection?

    Science.gov (United States)

    Susan E. Meyer; David L. Nelson; Suzette Clement; Alisa Ramakrishnan

    2010-01-01

    Evolutionary processes that maintain genetic diversity in plants are likely to include selection imposed by pathogens. Negative frequency-dependent selection is a mechanism for maintenance of resistance polymorphism in plant - pathogen interactions. We explored whether such selection operates in the Bromus tectorum - Ustilago bullata pathosystem. Gene-for-gene...

  9. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

    2009-11-11

    Ceralink Inc. developed FastFuse™, a rapid, new, energy saving process for lamination of glass and composites using radio frequency (RF) heating technology. The Inventions and Innovations program supported the technical and commercial research and development needed to elevate the innovation from bench scale to a self-supporting technology with significant potential for growth. The attached report provides an overview of the technical and commerical progress achieved for FastFuse™ during the course of the project. FastFuse™ has the potential to revolutionize the laminate manufacturing industries by replacing energy intensive, multi-step processes with an energy efficient, single-step process that allows higher throughput. FastFuse™ transmits RF energy directly into the interlayer to generate heat, eliminating the need to directly heat glass layers and the surrounding enclosures, such as autoclaves or vacuum systems. FastFuse™ offers lower start-up and energy costs (up to 90% or more reduction in energy costs), and faster cycles times (less than 5 minutes). FastFuse™ is compatible with EVA, TPU, and PVB interlayers, and has been demonstrated for glass, plastics, and multi-material structures such as photovoltaics and transparent armor.

  10. The Quasar Fraction in Low-Frequency Selected Complete Samples and Implications for Unified Schemes

    Science.gov (United States)

    Willott, Chris J.; Rawlings, Steve; Blundell, Katherine M.; Lacy, Mark

    2000-01-01

    Low-frequency radio surveys are ideal for selecting orientation-independent samples of extragalactic sources because the sample members are selected by virtue of their isotropic steep-spectrum extended emission. We use the new 7C Redshift Survey along with the brighter 3CRR and 6C samples to investigate the fraction of objects with observed broad emission lines - the 'quasar fraction' - as a function of redshift and of radio and narrow emission line luminosity. We find that the quasar fraction is more strongly dependent upon luminosity (both narrow line and radio) than it is on redshift. Above a narrow [OII] emission line luminosity of log(base 10) (L(sub [OII])/W) approximately > 35 [or radio luminosity log(base 10) (L(sub 151)/ W/Hz.sr) approximately > 26.5], the quasar fraction is virtually independent of redshift and luminosity; this is consistent with a simple unified scheme with an obscuring torus with a half-opening angle theta(sub trans) approximately equal 53 deg. For objects with less luminous narrow lines, the quasar fraction is lower. We show that this is not due to the difficulty of detecting lower-luminosity broad emission lines in a less luminous, but otherwise similar, quasar population. We discuss evidence which supports at least two probable physical causes for the drop in quasar fraction at low luminosity: (i) a gradual decrease in theta(sub trans) and/or a gradual increase in the fraction of lightly-reddened (0 approximately quasar luminosity; and (ii) the emergence of a distinct second population of low luminosity radio sources which, like M8T, lack a well-fed quasar nucleus and may well lack a thick obscuring torus.

  11. Allele frequency changes due to hitch-hiking in genomic selection programs

    DEFF Research Database (Denmark)

    Liu, Huiming; Sørensen, Anders Christian; Meuwissen, Theo H E

    2014-01-01

    of inbreeding due to changes in allele frequencies and hitch-hiking. This study aimed at understanding the impact of using long-term genomic selection on changes in allele frequencies, genetic variation and the level of inbreeding. Methods Selection was performed in simulated scenarios with a population of 400......-BLUP, Genomic BLUP and Bayesian Lasso. Changes in allele frequencies at QTL, markers and linked neutral loci were investigated for the different selection criteria and different scenarios, along with the loss of favourable alleles and the rate of inbreeding measured by pedigree and runs of homozygosity. Results...

  12. Mutational jackpot events generate effective frequency-dependent selection in adapting populations

    Science.gov (United States)

    Hallatschek, Oskar

    The site-frequency spectrum is one the most easily measurable quantities that characterize the genetic diversity of a population. While most neutral models predict that site frequency spectra should decay with increasing frequency, a high-frequency uptick has been reported in many populations. Anomalies in the high-frequency tail are particularly unsettling because the highest frequencies can be measured with greatest accuracy. Here, we show that an uptick in the spectrum of neutral mutations generally arises when mutant frequencies are dominated by rare jackpot events, mutational events with large descendant numbers. This leads to an effective pattern of frequency-dependent selection (or unstable internal equilibrium at one half frequency) that causes an accumulation of high-frequency polymorphic sites. We reproduce the known uptick occurring for recurrent hitchhiking (genetic draft) as well as rapid adaptation, and (in the future) generalize the shape of the high-frequency tail to other scenarios that are dominated by jackpot events, such as frequent range expansions. We also tackle (in the future) the inverse approach to use the high-frequency uptick for learning about the tail of the offspring number distribution. Positively selected alleles need to surpass, typically, an u NSF Career Award (PoLS), NIH NIGMS R01, Simons Foundation.

  13. Energy Saving Glass Lamination via Selective Radio-Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shulman, Holly S.; Allan, Shawn M.

    2009-11-11

    This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for

  14. The long-term evolution of multilocus traits under frequency-dependent disruptive selection

    NARCIS (Netherlands)

    Van Doorn, G. Sander; Dieckmann, Ulf

    Frequency-dependent disruptive selection is widely recognized as an important source of genetic variation. Its evolutionary consequences have been extensively studied using phenotypic evolutionary models, based on quantitative genetics, game theory, or adaptive dynamics. However, the genetic

  15. Multisource full waveform inversion of marine streamer data with frequency selection

    KAUST Repository

    Huang, Yunsong; Schuster, Gerard T.

    2013-01-01

    Multisource migration with frequency selection is now extended to multisource full waveform inversion (FWI) of supergathers for marine streamer data. There are three advantages of this approach compared to conventional FWI for marine streamer data. 1. The multisource FWI method with frequency selection is computationally more efficient than conventional FWI. 2. A supergather requires more than an order of magnitude less storage than the the original data. 3. Frequency selection overcomes the acquisition mismatch between the observed data and the simulated multisource supergathers for marine data. This mismatch problem has prevented the efficient application of FWI to marine geometries in the space-time domain. Preliminary result of applying multisource FWI with frequency selection to a synthetic marine data set suggests it is at least four times more efficient than standard FWI.

  16. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  17. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  18. Electromagnetic fields created by a beam in an axisymmetric infinitely thick single-layer resistive pipe: general formulas and low frequency approximations

    CERN Document Server

    Mounet, Nicolas Frank; CERN. Geneva. ATS Department

    2015-01-01

    This note provides general and approximate formulas for the electromagnetic fields created by a passing beam in an axisymmetric infinitely thick resistive pipe made of a single homogeneous layer. The full derivations and their resulting approximate expressions at low and intermediate frequencies are given here, as well as the conditions under which those approximations are valid. Beam-coupling impedances are also computed, and examples are shown.

  19. Top down and bottom up selection drives variations in frequency and form of a visual signal

    OpenAIRE

    Yeh, Chien-Wei; Blamires, Sean J.; Liao, Chen-Pan; Tso, I.-Min

    2015-01-01

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey, selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selecti...

  20. Full Waveform Inversion with Multisource Frequency Selection of Marine Streamer Data

    KAUST Repository

    Huang, Yunsong; Schuster, Gerard T.

    2017-01-01

    The theory and practice of multisource full waveform inversion of marine supergathers are described with a frequency-selection strategy. The key enabling property of frequency selection is that it eliminates the crosstalk among sources, thus overcoming the aperture mismatch of marine multisource inversion. Tests on multisource full waveform inversion of synthetic marine data and Gulf of Mexico data show speedups of 4× and 8×, respectively, compared to conventional full waveform inversion.

  1. Full Waveform Inversion with Multisource Frequency Selection of Marine Streamer Data

    KAUST Repository

    Huang, Yunsong

    2017-10-27

    The theory and practice of multisource full waveform inversion of marine supergathers are described with a frequency-selection strategy. The key enabling property of frequency selection is that it eliminates the crosstalk among sources, thus overcoming the aperture mismatch of marine multisource inversion. Tests on multisource full waveform inversion of synthetic marine data and Gulf of Mexico data show speedups of 4× and 8×, respectively, compared to conventional full waveform inversion.

  2. A new method of hybrid frequency hopping signals selection and blind parameter estimation

    Science.gov (United States)

    Zeng, Xiaoyu; Jiao, Wencheng; Sun, Huixian

    2018-04-01

    Frequency hopping communication is widely used in military communications at home and abroad. In the case of single-channel reception, it is scarce to process multiple frequency hopping signals both effectively and simultaneously. A method of hybrid FH signals selection and blind parameter estimation is proposed. The method makes use of spectral transformation, spectral entropy calculation and PRI transformation basic theory to realize the sorting and parameter estimation of the components in the hybrid frequency hopping signal. The simulation results show that this method can correctly classify the frequency hopping component signal, and the estimated error of the frequency hopping period is about 5% and the estimated error of the frequency hopping frequency is less than 1% when the SNR is 10dB. However, the performance of this method deteriorates seriously at low SNR.

  3. High-Frequency Guided Wave Scattering by a Partly Through-Thickness Hole Based on 3D Theory

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Xu Jian; Ma Shi-Wei

    2015-01-01

    We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The S0 wave is incident at the frequency above the A1 mode cut-off frequency, in which the popular approximate plate theories are inapplicable. Due to the non-symmetric blind hole defect, the scattered fields will contain higher order converted modes in addition to the fundamental S0 and A0 modes. The far-field scattering amplitudes of various propagating Lamb modes for different hole sizes are inspected. The results are compared with those of lower frequencies and some different phenomena are found. Two-dimensional Fourier transform (2DFT) results of transient scattered Lamb and SH wave signals agree well with the analytical dispersion curves, which check the validity of the solutions from another point of view. (paper)

  4. Frequency shift of a crystal quartz resonator in thickness-shear modes induced by an array of hemispherical material units.

    Science.gov (United States)

    Yuantai Hu; Huiliang Hu; Bin Luo; Huan Xue; Jiemin Xie; Ji Wang

    2013-08-01

    A two-dimensional model was established to study the dynamic characteristics of a quartz crystal resonator with the upper surface covered by an array of hemispherical material units. A frequency-dependent equivalent mass ratio was proposed to simulate the effect of the covered units on frequency shift of the resonator system. It was found that the equivalent mass ratio alternately becomes positive or negative with change of shear modulus and radius of each material unit, which indicates that the equivalent mass ratio is strongly related to the vibration mode of the covered loadings. The further numerical results show the cyclical feature in the relationship of frequency shift and shear modulus/radius as expected. The solutions are useful in the analysis of frequency stability of quartz resonators and acoustic wave sensors.

  5. Global blending optimization of laminated composites with discrete material candidate selection and thickness variation

    DEFF Research Database (Denmark)

    Sørensen, Søren N.; Stolpe, Mathias

    2015-01-01

    rate. The capabilities of the method and the effect of active versus inactive manufacturing constraints are demonstrated on several numerical examples of limited size, involving at most 320 binary variables. Most examples are solved to guaranteed global optimality and may constitute benchmark examples...... but is, however, convex in the original mixed binary nested form. Convexity is the foremost important property of optimization problems, and the proposed method can guarantee the global or near-global optimal solution; unlike most topology optimization methods. The material selection is limited...... for popular topology optimization methods and heuristics based on solving sequences of non-convex problems. The results will among others demonstrate that the difficulty of the posed problem is highly dependent upon the composition of the constitutive properties of the material candidates....

  6. Tuning In to Sound: Frequency-Selective Attentional Filter in Human Primary Auditory Cortex

    Science.gov (United States)

    Da Costa, Sandra; van der Zwaag, Wietske; Miller, Lee M.; Clarke, Stephanie

    2013-01-01

    Cocktail parties, busy streets, and other noisy environments pose a difficult challenge to the auditory system: how to focus attention on selected sounds while ignoring others? Neurons of primary auditory cortex, many of which are sharply tuned to sound frequency, could help solve this problem by filtering selected sound information based on frequency-content. To investigate whether this occurs, we used high-resolution fMRI at 7 tesla to map the fine-scale frequency-tuning (1.5 mm isotropic resolution) of primary auditory areas A1 and R in six human participants. Then, in a selective attention experiment, participants heard low (250 Hz)- and high (4000 Hz)-frequency streams of tones presented at the same time (dual-stream) and were instructed to focus attention onto one stream versus the other, switching back and forth every 30 s. Attention to low-frequency tones enhanced neural responses within low-frequency-tuned voxels relative to high, and when attention switched the pattern quickly reversed. Thus, like a radio, human primary auditory cortex is able to tune into attended frequency channels and can switch channels on demand. PMID:23365225

  7. Effect of thickness on structural, corrosion and mechanical properties of a thin ZrN film deposited by medium frequency (MF) reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kavitha, Ayyalu; Kannan, Raman [Anna Univ., Dindigul (India). Dept. of Physics; Loganathan, Subramani [Titan Industries, Hosur, Tamilnadu (India). Ion Plating Dept.

    2016-07-01

    Zirconium nitride (ZrN) thin films were prepared on stainless steel (SS) substrates by medium frequency (MF) reactive sputtering with gas ion source (GIS) by varying the deposition time and obtained thickness (t{sub ZrN}) in the range of 1.25 to 3.24 μm. The effect of thickness on the structural and microstructural properties was studied using XRD and AFM. XRD characterization revealed that the texture of the ZrN thin films changes as a function of thickness. Both, the (111) and (200) peak, appear initially and (111) becomes more intense with increasing t{sub ZrN}. AFM imaging revealed that the ZrN thin film coated with t{sub ZrN} ∼ 3.24 μm shows larger grains that are uniformly distributed over the surface. An average hardness value of 19.79 GPa was observed for ZrN thin films having t{sub ZrN} ∼ 3.24 μm. The ZrN thin films having t{sub ZrN} ∼ 3.24 μm exhibits better adhesion strength up to 20 N. The electrochemical polarization studies indicated that the ZrN thin film having larger thickness shows improved corrosion resistance compared to SS in 3.5 % NaCl solution.

  8. Least-squares reverse time migration of marine data with frequency-selection encoding

    KAUST Repository

    Dai, Wei

    2013-08-20

    The phase-encoding technique can sometimes increase the efficiency of the least-squares reverse time migration (LSRTM) by more than one order of magnitude. However, traditional random encoding functions require all the encoded shots to share the same receiver locations, thus limiting the usage to seismic surveys with a fixed spread geometry. We implement a frequency-selection encoding strategy that accommodates data with a marine streamer geometry. The encoding functions are delta functions in the frequency domain, so that all the en- coded shots have unique non-overlapping frequency content, and the receivers can distinguish the wavefield from each shot with a unique frequency band. Since the encoding functions are orthogonal to each other, there will be no crosstalk between different shots during modeling and migration. With the frequency-selection encoding method, the computational efficiency of LSRTM is increased so that its cost is compara- ble to conventional RTM for both the Marmousi2 model and a marine data set recorded in the Gulf of Mexico. With more iterations, the LSRTM image quality is further improved. We conclude that LSRTM with frequency-selection is an efficient migration method that can sometimes produce more focused images than conventional RTM.

  9. The yule approximation for the site frequency spectrum after a selective sweep.

    Directory of Open Access Journals (Sweden)

    Sebastian Bossert

    Full Text Available In the area of evolutionary theory, a key question is which portions of the genome of a species are targets of natural selection. Genetic hitchhiking is a theoretical concept that has helped to identify various such targets in natural populations. In the presence of recombination, a severe reduction in sequence diversity is expected around a strongly beneficial allele. The site frequency spectrum is an important tool in genome scans for selection and is composed of the numbers S(1,...,S(n-1, where S(k is the number of single nucleotide polymorphisms (SNPs present in k from n individuals. Previous work has shown that both the number of low- and high-frequency variants are elevated relative to neutral evolution when a strongly beneficial allele fixes. Here, we follow a recent investigation of genetic hitchhiking using a marked Yule process to obtain an analytical prediction of the site frequency spectrum in a panmictic population at the time of fixation of a highly beneficial mutation. We combine standard results from the neutral case with the effects of a selective sweep. As simulations show, the resulting formula produces predictions that are more accurate than previous approaches for the whole frequency spectrum. In particular, the formula correctly predicts the elevation of low- and high-frequency variants and is significantly more accurate than previously derived formulas for intermediate frequency variants.

  10. Selective attention modulates human auditory brainstem responses: relative contributions of frequency and spatial cues.

    Directory of Open Access Journals (Sweden)

    Alexandre Lehmann

    Full Text Available Selective attention is the mechanism that allows focusing one's attention on a particular stimulus while filtering out a range of other stimuli, for instance, on a single conversation in a noisy room. Attending to one sound source rather than another changes activity in the human auditory cortex, but it is unclear whether attention to different acoustic features, such as voice pitch and speaker location, modulates subcortical activity. Studies using a dichotic listening paradigm indicated that auditory brainstem processing may be modulated by the direction of attention. We investigated whether endogenous selective attention to one of two speech signals affects amplitude and phase locking in auditory brainstem responses when the signals were either discriminable by frequency content alone, or by frequency content and spatial location. Frequency-following responses to the speech sounds were significantly modulated in both conditions. The modulation was specific to the task-relevant frequency band. The effect was stronger when both frequency and spatial information were available. Patterns of response were variable between participants, and were correlated with psychophysical discriminability of the stimuli, suggesting that the modulation was biologically relevant. Our results demonstrate that auditory brainstem responses are susceptible to efferent modulation related to behavioral goals. Furthermore they suggest that mechanisms of selective attention actively shape activity at early subcortical processing stages according to task relevance and based on frequency and spatial cues.

  11. Least-squares reverse time migration of marine data with frequency-selection encoding

    KAUST Repository

    Dai, Wei

    2013-06-24

    The phase-encoding technique can sometimes increase the efficiency of the least-squares reverse time migration (LSRTM) by more than one order of magnitude. However, traditional random encoding functions require all the encoded shots to share the same receiver locations, thus limiting the usage to seismic surveys with a fixed spread geometry. We implement a frequency-selection encoding strategy that accommodates data with a marine streamer geometry. The encoding functions are delta functions in the frequency domain, so that all the encoded shots have unique nonoverlapping frequency content, and the receivers can distinguish the wavefield from each shot with a unique frequency band. Because the encoding functions are orthogonal to each other, there will be no crosstalk between different shots during modeling and migration. With the frequency-selection encoding method, the computational efficiency of LSRTM is increased so that its cost is comparable to conventional RTM for the Marmousi2 model and a marine data set recorded in the Gulf of Mexico. With more iterations, the LSRTM image quality is further improved by suppressing migration artifacts, balancing reflector amplitudes, and enhancing the spatial resolution. We conclude that LSRTM with frequency-selection is an efficient migration method that can sometimes produce more focused images than conventional RTM. © 2013 Society of Exploration Geophysicists.

  12. Top down and bottom up selection drives variations in frequency and form of a visual signal.

    Science.gov (United States)

    Yeh, Chien-Wei; Blamires, Sean J; Liao, Chen-Pan; Tso, I-Min

    2015-03-30

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selection on decoration frequency and form variation difficult to discern. Here we used dummy spiders and decorations to simulate four possible strategies that the spider Argiope aemula may choose and measured the prey and predator attraction consequences for each in the field. The strategy of decorating at a high frequency with a variable form attracted the most prey, while that of decorating at a high frequency with a fixed form attracted the most predators. These results suggest that mitigating the cost of attracting predators while maintaining prey attraction drives the use of variation in decoration form by many Argiope spp. when decorating frequently. Our study highlights the importance of considering top-down and bottom up selection pressure when devising evolutionary ecology experiments.

  13. Signatures of positive selection: from selective sweeps at individual loci to subtle allele frequency changes in polygenic adaptation.

    Science.gov (United States)

    Stephan, Wolfgang

    2016-01-01

    In the past 15 years, numerous methods have been developed to detect selective sweeps underlying adaptations. These methods are based on relatively simple population genetic models, including one or two loci at which positive directional selection occurs, and one or two marker loci at which the impact of selection on linked neutral variation is quantified. Information about the phenotype under selection is not included in these models (except for fitness). In contrast, in the quantitative genetic models of adaptation, selection acts on one or more phenotypic traits, such that a genotype-phenotype map is required to bridge the gap to population genetics theory. Here I describe the range of population genetic models from selective sweeps in a panmictic population of constant size to evolutionary traffic when simultaneous sweeps at multiple loci interfere, and I also consider the case of polygenic selection characterized by subtle allele frequency shifts at many loci. Furthermore, I present an overview of the statistical tests that have been proposed based on these population genetics models to detect evidence for positive selection in the genome. © 2015 John Wiley & Sons Ltd.

  14. Predicting the impact of selection for scrapie resistance on PRNP genotype frequencies in goats.

    Science.gov (United States)

    Sacchi, Paola; Rasero, Roberto; Ru, Giuseppe; Aiassa, Eleonora; Colussi, Silvia; Ingravalle, Francesco; Peletto, Simone; Perrotta, Maria Gabriella; Sartore, Stefano; Soglia, Dominga; Acutis, Pierluigi

    2018-03-06

    The European Union has implemented breeding programmes to increase scrapie resistance in sheep. A similar approach can be applied also in goats since the K222 allele provides a level of resistance equivalent to that of ARR in sheep. The European Food Safety Authority stated that breeding for resistance could be offered as an option for Member States to control classical scrapie in goats. We assessed the impact of different breeding strategies on PRNP genotype frequencies using a mathematical model that describes in detail the evolution of K222 in two goat breeds, Chamois Coloured and Saanen. Different patterns of age structure and replacement rate were modelled as factors affecting response to selection. Breeding for scrapie resistance can be implemented in goats, even though the initial K222 frequencies in these breeds are not particularly favourable and the rate at which the resistant animals increase, both breeding and slaughtered for meat production, is slow. If the goal is not to achieve the fixation of resistance allele, it is advisable to carry out selection only until a desired frequency of K222-carriers has been attained. Nucleus selection vs. selection on the overall populations is less expensive but takes longer to reach the desired output. The programme performed on the two goat breeds serves as a model of the response the selection could have in other breeds that show different initial frequencies and population structure. In this respect, the model has a general applicability.

  15. Mechanical frequency selectivity of an artificial basilar membrane using a beam array with narrow supports

    International Nuclear Information System (INIS)

    Kim, Sangwon; Jang, Jongmoon; Choi, Hongsoo; Song, Won Joon; Jang, Jeong Hun

    2013-01-01

    The study presented in this paper assessed the frequency selectivity of an artificial basilar membrane (ABM) constructed using a piezoelectric beam array with narrow supports. Three ABM samples were constructed. Each ABM contained 16 beams with various lengths in a one-dimensional array. To experimentally assess the frequency selectivity of the ABM, mechanical vibration induced either by an electrical or an acoustic stimulus was measured with a scanning laser-Doppler vibrometer. The electro-mechanical and acousto-mechanical transfer functions were defined for the same purpose. The tonotopy of each beam array was visualized by post-processing the experimental results. Finite element analyses were conducted to numerically compute the resonance frequencies, identify the associated vibrational modes, and evaluate the harmonic responses of the beams. The influence of the residual stresses existing in the beams was reflected in the geometric models by introducing three different levels of arc-shaped lateral deformations in the beams. The harmonic analyses revealed that each beam of the ABM samples presented independent band-pass characteristics. The experiments and simulations commonly showed a frequency selectivity of the fabricated ABMs in the range of 2–20 kHz. Therefore, the device is suitable for development of a totally implantable artificial cochlea, implementing a mechanical frequency analyzer. This work is part of research to develop a prototype of a totally implantable artificial cochlea. (paper)

  16. Individual Alpha Peak Frequency Predicts 10 Hz Flicker Effects on Selective Attention.

    Science.gov (United States)

    Gulbinaite, Rasa; van Viegen, Tara; Wieling, Martijn; Cohen, Michael X; VanRullen, Rufin

    2017-10-18

    Rhythmic visual stimulation ("flicker") is primarily used to "tag" processing of low-level visual and high-level cognitive phenomena. However, preliminary evidence suggests that flicker may also entrain endogenous brain oscillations, thereby modulating cognitive processes supported by those brain rhythms. Here we tested the interaction between 10 Hz flicker and endogenous alpha-band (∼10 Hz) oscillations during a selective visuospatial attention task. We recorded EEG from human participants (both genders) while they performed a modified Eriksen flanker task in which distractors and targets flickered within (10 Hz) or outside (7.5 or 15 Hz) the alpha band. By using a combination of EEG source separation, time-frequency, and single-trial linear mixed-effects modeling, we demonstrate that 10 Hz flicker interfered with stimulus processing more on incongruent than congruent trials (high vs low selective attention demands). Crucially, the effect of 10 Hz flicker on task performance was predicted by the distance between 10 Hz and individual alpha peak frequency (estimated during the task). Finally, the flicker effect on task performance was more strongly predicted by EEG flicker responses during stimulus processing than during preparation for the upcoming stimulus, suggesting that 10 Hz flicker interfered more with reactive than proactive selective attention. These findings are consistent with our hypothesis that visual flicker entrained endogenous alpha-band networks, which in turn impaired task performance. Our findings also provide novel evidence for frequency-dependent exogenous modulation of cognition that is determined by the correspondence between the exogenous flicker frequency and the endogenous brain rhythms. SIGNIFICANCE STATEMENT Here we provide novel evidence that the interaction between exogenous rhythmic visual stimulation and endogenous brain rhythms can have frequency-specific behavioral effects. We show that alpha-band (10 Hz) flicker impairs stimulus

  17. Negative frequency-dependent selection between Pasteuria penetrans and its host Meloidogyne arenaria

    Science.gov (United States)

    In negative frequency-dependant selection (NFDS), parasite genotypes capable of infecting the numerically dominant host genotype are favored, while host genotypes resistant to the dominant parasite genotype are favored, creating a cyclical pattern of resistant genotypes in the host population and, a...

  18. Detection of optic nerve lesions in optic neuritis using frequency-selective fat-saturation sequences

    International Nuclear Information System (INIS)

    Miller, D.H.; MacManus, D.G.; Bartlett, P.A.; Kapoor, R.; Morrissey, S.P.; Moseley, I.F.

    1993-01-01

    MRI was performed on seven patients with acute optic neuritis, using two sequences which suppress the signal from orbital fat: frequency-selective fat-saturation and inversion recovery with a short inversion time. Lesions were seen on both sequences in all the symptomatic optic nerves studied. (orig.)

  19. Secured Communication over Frequency-Selective Fading Channels: A Practical Vandermonde Precoding

    Directory of Open Access Journals (Sweden)

    Mari Kobayashi

    2009-01-01

    Full Text Available We study the frequency-selective broadcast channel with confidential messages (BCC where the transmitter sends a confidential message to receiver 1 and a common message to receivers 1 and 2. In the case of a block transmission of N symbols followed by a guard interval of L symbols, the frequency-selective channel can be modeled as a N×(N+L Toeplitz matrix. For this special type of multiple-input multiple-output channels, we propose a practical Vandermonde precoding that projects the confidential messages in the null space of the channel seen by receiver 2 while superposing the common message. For this scheme, we provide the achievable rate region and characterize the optimal covariance for some special cases of interest. Interestingly, the proposed scheme can be applied to other multiuser scenarios such as the K+1-user frequency-selective BCC with K confidential messages and the two-user frequency-selective BCC with two confidential messages. For each scenario, we provide the secrecy degree of freedom (s.d.o.f. region of the corresponding channel and prove the optimality of the Vandermonde precoding. One of the appealing features of the proposed scheme is that it does not require any specific secrecy encoding technique but can be applied on top of any existing powerful encoding schemes.

  20. Secured Communication over Frequency-Selective Fading Channels: A Practical Vandermonde Precoding

    Directory of Open Access Journals (Sweden)

    Debbah Mérouane

    2009-01-01

    Full Text Available We study the frequency-selective broadcast channel with confidential messages (BCC where the transmitter sends a confidential message to receiver 1 and a common message to receivers 1 and 2. In the case of a block transmission of symbols followed by a guard interval of symbols, the frequency-selective channel can be modeled as a Toeplitz matrix. For this special type of multiple-input multiple-output channels, we propose a practical Vandermonde precoding that projects the confidential messages in the null space of the channel seen by receiver 2 while superposing the common message. For this scheme, we provide the achievable rate region and characterize the optimal covariance for some special cases of interest. Interestingly, the proposed scheme can be applied to other multiuser scenarios such as the -user frequency-selective BCC with confidential messages and the two-user frequency-selective BCC with two confidential messages. For each scenario, we provide the secrecy degree of freedom (s.d.o.f. region of the corresponding channel and prove the optimality of the Vandermonde precoding. One of the appealing features of the proposed scheme is that it does not require any specific secrecy encoding technique but can be applied on top of any existing powerful encoding schemes.

  1. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

    Science.gov (United States)

    Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.

    2015-12-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.

  2. Ferrite Film Loaded Frequency Selective Metamaterials for Sub-GHz Applications

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2016-12-01

    Full Text Available Electromagnetic metamaterials are constructed with sub-wavelength structures that exhibit particular electromagnetic properties under a certain frequency range. Because the form-factor of the substructures has to be comparable to the wavelength of the operating frequency, few papers have discussed the metamaterials under GHz frequency. In this paper, we developed an innovative method to reduce the resonant frequency of metamaterals. By integrating the meta-structures with ferrite materials of higher permeability, the cell size of the meta-structure can be scaled down. This paper describes the methodology, design, and development of low-profile GHz ferrite loaded metamaterials. A ferrite film with a permeability of 20 could reduce the resonant frequency of metamaterials by up to 50%. A prototype has been fabricated and the measurement data align well with the simulation results. Because of the lowered operational frequency, the proposed ferrite loaded metamaterials offer more flexibility for various sub-GHz microwave applications, such as cloaks, absorbers, and frequency selective surfaces.

  3. How does male–male competition generate negative frequency-dependent selection and disruptive selection during speciation?

    Science.gov (United States)

    Border, Shana E

    2018-01-01

    Abstract Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male–male competition in speciation is relatively understudied. Here, we outline how male–male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection (advantage of rare phenotype arising from stronger male–male competition between similar male phenotypes compared with dissimilar male phenotypes) and disruptive selection (advantage of extreme phenotypes) drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male–male competition interacts with other life-history functions and that variable male competitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on competitor signals. We call for a better integration of male–male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mechanisms. Altogether, we present a more comprehensive framework for studying the role of male–male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions. PMID:29492042

  4. Design, Fabrication and Characterization of MIM Diodes and Frequency Selective Thermal Emitters for Solar Energy Harvesting and Detection Devices

    Science.gov (United States)

    Sharma, Saumya

    Energy harvesting using rectennas for infrared radiation continues to be a challenge due to the lack of fast switching diodes capable of rectification at THz frequencies. Metal insulator metal diodes which may be used at 30 THz must show adequate nonlinearity for small signal rectification such as 30 mV. In a rectenna assembly, the voltage signal received as an output from a single nanoantenna can be as small as ~30microV. Thus, only a hybrid array of nanoantennas can be sufficient to provide a signal in the ~30mV range for the diode to be able to rectify around 30THz. A metal-insulator-metal diode with highly nonlinear I-V characteristics is required in order for such small signal rectification to be possible. Such diode fabrication was found to be faced with two major fabrication challenges. The first one being the lack of a precisely controlled deposition process to allow a pinhole free insulator deposition less than 3nm in thickness. Another major challenge is the deposition of a top metal contact on the underlying insulating thin film. As a part of this research study, most of the MIM diodes were fabricated using Langmuir Blodgett monolayers deposited on a thin Ni film that was sputter coated on a silicon wafer. UV induced polymerization of the Langmuir Blodgett thin film was used to allow intermolecular crosslinking. A metal top contact was sputtered onto the underlying Langmuir Blodgett film assembly. In addition to material characterization of all the individual films using IR, UV-VIS spectroscopy, electron microscopy and atomic force microscopy, the I-V characteristics, resistance, current density, rectification ratio and responsivity with respect to the bias voltage were also measured for the electrical characterization of these MIM diodes. Further improvement in the diode rectification ratio and responsivity was obtained with Langmuir Blodgett films grown by the use of horizontally oriented organic molecules, due to a smaller tunneling distance that

  5. Selective injection locking of a multi-mode semiconductor laser to a multi-frequency reference beam

    Science.gov (United States)

    Pramod, Mysore Srinivas; Yang, Tao; Pandey, Kanhaiya; Giudici, Massimo; Wilkowski, David

    2014-07-01

    Injection locking is a well known and commonly used method for coherent light amplification. Usually injection locking is obtained on a single-mode laser injected by a single-frequency seeding beam. In this work we show that selective injection locking of a single-frequency may also be achieved on a multi-mode semiconductor laser injected by a multi-frequency seeding beam, if the slave laser provides sufficient frequency filtering. This selective injection locking condition depends critically on the frequency detuning between the free-running slave emission frequency and each injected frequency component. Stable selective injection locking to a set of three seeding components separated by 1.2 GHz is obtained. This system provides an amplification up to 37 dB of each component. This result suggests that, using distinct slave lasers for each frequency line, a set of mutually coherent high-power radiation modes can be tuned in the GHz frequency domain.

  6. Cortical drive of low-frequency oscillations in the human nucleus accumbens during action selection.

    Science.gov (United States)

    Stenner, Max-Philipp; Litvak, Vladimir; Rutledge, Robb B; Zaehle, Tino; Schmitt, Friedhelm C; Voges, Jürgen; Heinze, Hans-Jochen; Dolan, Raymond J

    2015-07-01

    The nucleus accumbens is thought to contribute to action selection by integrating behaviorally relevant information from multiple regions, including prefrontal cortex. Studies in rodents suggest that information flow to the nucleus accumbens may be regulated via task-dependent oscillatory coupling between regions. During instrumental behavior, local field potentials (LFP) in the rat nucleus accumbens and prefrontal cortex are coupled at delta frequencies (Gruber AJ, Hussain RJ, O'Donnell P. PLoS One 4: e5062, 2009), possibly mediating suppression of afferent input from other areas and thereby supporting cortical control (Calhoon GG, O'Donnell P. Neuron 78: 181-190, 2013). In this report, we demonstrate low-frequency cortico-accumbens coupling in humans, both at rest and during a decision-making task. We recorded LFP from the nucleus accumbens in six epilepsy patients who underwent implantation of deep brain stimulation electrodes. All patients showed significant coherence and phase-synchronization between LFP and surface EEG at delta and low theta frequencies. Although the direction of this coupling as indexed by Granger causality varied between subjects in the resting-state data, all patients showed a cortical drive of the nucleus accumbens during action selection in a decision-making task. In three patients this was accompanied by a significant coherence increase over baseline. Our results suggest that low-frequency cortico-accumbens coupling represents a highly conserved regulatory mechanism for action selection. Copyright © 2015 the American Physiological Society.

  7. Vast Volatility Matrix Estimation using High Frequency Data for Portfolio Selection*

    Science.gov (United States)

    Fan, Jianqing; Li, Yingying; Yu, Ke

    2012-01-01

    Portfolio allocation with gross-exposure constraint is an effective method to increase the efficiency and stability of portfolios selection among a vast pool of assets, as demonstrated in Fan et al. (2011). The required high-dimensional volatility matrix can be estimated by using high frequency financial data. This enables us to better adapt to the local volatilities and local correlations among vast number of assets and to increase significantly the sample size for estimating the volatility matrix. This paper studies the volatility matrix estimation using high-dimensional high-frequency data from the perspective of portfolio selection. Specifically, we propose the use of “pairwise-refresh time” and “all-refresh time” methods based on the concept of “refresh time” proposed by Barndorff-Nielsen et al. (2008) for estimation of vast covariance matrix and compare their merits in the portfolio selection. We establish the concentration inequalities of the estimates, which guarantee desirable properties of the estimated volatility matrix in vast asset allocation with gross exposure constraints. Extensive numerical studies are made via carefully designed simulations. Comparing with the methods based on low frequency daily data, our methods can capture the most recent trend of the time varying volatility and correlation, hence provide more accurate guidance for the portfolio allocation in the next time period. The advantage of using high-frequency data is significant in our simulation and empirical studies, which consist of 50 simulated assets and 30 constituent stocks of Dow Jones Industrial Average index. PMID:23264708

  8. Vast Volatility Matrix Estimation using High Frequency Data for Portfolio Selection.

    Science.gov (United States)

    Fan, Jianqing; Li, Yingying; Yu, Ke

    2012-01-01

    Portfolio allocation with gross-exposure constraint is an effective method to increase the efficiency and stability of portfolios selection among a vast pool of assets, as demonstrated in Fan et al. (2011). The required high-dimensional volatility matrix can be estimated by using high frequency financial data. This enables us to better adapt to the local volatilities and local correlations among vast number of assets and to increase significantly the sample size for estimating the volatility matrix. This paper studies the volatility matrix estimation using high-dimensional high-frequency data from the perspective of portfolio selection. Specifically, we propose the use of "pairwise-refresh time" and "all-refresh time" methods based on the concept of "refresh time" proposed by Barndorff-Nielsen et al. (2008) for estimation of vast covariance matrix and compare their merits in the portfolio selection. We establish the concentration inequalities of the estimates, which guarantee desirable properties of the estimated volatility matrix in vast asset allocation with gross exposure constraints. Extensive numerical studies are made via carefully designed simulations. Comparing with the methods based on low frequency daily data, our methods can capture the most recent trend of the time varying volatility and correlation, hence provide more accurate guidance for the portfolio allocation in the next time period. The advantage of using high-frequency data is significant in our simulation and empirical studies, which consist of 50 simulated assets and 30 constituent stocks of Dow Jones Industrial Average index.

  9. Temporal mode selectivity by frequency conversion in second-order nonlinear optical waveguides

    DEFF Research Database (Denmark)

    Reddy, D. V.; Raymer, M. G.; McKinstrie, C. J.

    2013-01-01

    in a transparent optical network using temporally orthogonal waveforms to encode different channels. We model the process using coupled-mode equations appropriate for wave mixing in a uniform second-order nonlinear optical medium pumped by a strong laser pulse. We find Green functions describing the process...... in this optimal regime. We also find an operating regime in which high-efficiency frequency conversion without temporal-shape selectivity can be achieved while preserving the shapes of a wide class of input pulses. The results are applicable to both classical and quantum frequency conversion....

  10. Analysis of Broad-band Frequency Selective Shielding Glass by FDTD method

    OpenAIRE

    笠嶋, 善憲; Kasashima, Yoshinori

    2010-01-01

    A frequency Selective shielding (FSS) glass is a print of many same size antennas on a sheet of glass, and it has high shielding properties for one specific frequency. In the past, the author analyzed theoretically the characteristics of the FSS, as a large scale array antenna. The FSS has narrow-band shielding characteristics. This time, the author analyzed accurately the characteristics of a FSS glass being a print of many same size dipole antennas on a sheet of glass by FDTD method. As the...

  11. JNDS of interaural time delay (ITD) of selected frequency bands in speech and music signals

    Science.gov (United States)

    Aliphas, Avner; Colburn, H. Steven; Ghitza, Oded

    2002-05-01

    JNDS of interaural time delay (ITD) of selected frequency bands in the presence of other frequency bands have been reported for noiseband stimuli [Zurek (1985); Trahiotis and Bernstein (1990)]. Similar measurements will be reported for speech and music signals. When stimuli are synthesized with bandpass/band-stop operations, performance with complex stimuli are similar to noisebands (JNDS in tens or hundreds of microseconds); however, the resulting waveforms, when viewed through a model of the auditory periphery, show distortions (irregularities in phase and level) at the boundaries of the target band of frequencies. An alternate synthesis method based upon group-delay filtering operations does not show these distortions and is being used for the current measurements. Preliminary measurements indicate that when music stimuli are created using the new techniques, JNDS of ITDs are increased significantly compared to previous studies, with values on the order of milliseconds.

  12. Generation of radio vortex beams with designable polarization using anisotropic frequency selective surface

    Science.gov (United States)

    Yang, Jin; Zhang, Cheng; Ma, Hui Feng; Zhao, Jie; Dai, Jun Yan; Yuan, Wei; Yang, Liu Xi; Cheng, Qiang; Cui, Tie Jun

    2018-05-01

    We propose a strategy to convert a linearly polarized wave from a single point source to an orbital angular momentum (OAM) wave by arbitrary polarization via an anisotropic frequency selective surface (FSS) in the microwave frequency. By tailoring the geometries of FSS elements, reflection-phases in x and y polarizations are engineered and encoded independently, which allows us to design the eventual polarization state of the generated OAM vortex beam by elaborately selecting individual coding sequences for each polarization. Two types of FSSs are designed and experimentally characterized to demonstrate the capability of OAM generation with circular and linear polarizations, respectively, showing excellent performance in a wide bandwidth from 14 to 16 GHz. This method provides opportunities for polarization multiplexing in microwave OAM communication systems.

  13. A Smartphone Application for Customized Frequency Table Selection in Cochlear Implants.

    Science.gov (United States)

    Jethanamest, Daniel; Azadpour, Mahan; Zeman, Annette M; Sagi, Elad; Svirsky, Mario A

    2017-09-01

    A novel smartphone-based software application can facilitate self-selection of frequency allocation tables (FAT) in postlingually deaf cochlear implant (CI) users. CIs use FATs to represent the tonotopic organization of a normal cochlea. Current CI fitting methods typically use a standard FAT for all patients regardless of individual differences in cochlear size and electrode location. In postlingually deaf patients, different amounts of mismatch can result between the frequency-place function they experienced when they had normal hearing and the frequency-place function that results from the standard FAT. For some CI users, an alternative FAT may enhance sound quality or speech perception. Currently, no widely available tools exist to aid real-time selection of different FATs. This study aims to develop a new smartphone tool for this purpose and to evaluate speech perception and sound quality measures in a pilot study of CI subjects using this application. A smartphone application for a widely available mobile platform (iOS) was developed to serve as a preprocessor of auditory input to a clinical CI speech processor and enable interactive real-time selection of FATs. The application's output was validated by measuring electrodograms for various inputs. A pilot study was conducted in six CI subjects. Speech perception was evaluated using word recognition tests. All subjects successfully used the portable application with their clinical speech processors to experience different FATs while listening to running speech. The users were all able to select one table that they judged provided the best sound quality. All subjects chose a FAT different from the standard FAT in their everyday clinical processor. Using the smartphone application, the mean consonant-nucleus-consonant score with the default FAT selection was 28.5% (SD 16.8) and 29.5% (SD 16.4) when using a self-selected FAT. A portable smartphone application enables CI users to self-select frequency allocation

  14. Frequency Selective Properties of Coaxial Transmission Lines Loaded with Combined Artificial Inclusions

    Directory of Open Access Journals (Sweden)

    Francisco Falcone

    2014-01-01

    Full Text Available The properties of a modified coaxial transmission line by periodic inclusions will be discussed. The introduction of split ring resonators, conductor stubs, air gaps, and combination of these gives rise to new frequency selective properties, such as stopband or passband behavior, observable in planar as well as volumetric metamaterial structures. These results envisage new potential applications and implementation of devices in coaxial transmission line technology.

  15. Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves

    OpenAIRE

    Hashimoto, Yusuke; Bossini, Davide; Johansen, Tom H.; Saitoh, Eiji; Kirilyuk, Andrei; Rasing, Theo

    2017-01-01

    Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of s...

  16. Radio frequency selective addressing of localized atoms in a periodic potential

    International Nuclear Information System (INIS)

    Ott, H.; De Mirandes, E.; Ferlaino, F.; Roati, G.; Tuerck, V.; Modugno, G.; Inguscio, M.

    2004-01-01

    We study the localization and addressability of ultracold atoms in a combined parabolic and periodic potential. Such a potential supports the existence of localized stationary states and we show that applying a radio frequency field allows us to selectively address atoms in these states. This method is used to measure the energy and momentum distribution of the atoms in the localized states. We also discuss possible extensions of this scheme to address and manipulate atoms in single lattice sites

  17. A study of the impact of frequency selectivity on link adaptive wireless LAN systems

    OpenAIRE

    Armour, SMD; Doufexi, A; Nix, AR; Bull, DR

    2002-01-01

    Wireless local area networks (WLANs) supporting broadband multimedia communication are being developed and standardized around the world. The HIPERLAN/2, 802.11a and HiSWANa standards provide channel adaptive data rates between 6 and 54 Mbps in the 5GHz radio band. The link adaptation mechanism is not specified in the standards. In this paper the performance of the HIPERLAN/2 system is evaluated in terms of throughput in a range of test channels with different degrees of frequency selectivity...

  18. Impact of parents’ nutritional knowledge on the nutrition and frequency of consumption of selected products in children and adolescents practicing football in a football club in Bydgoszcz, Poland

    Directory of Open Access Journals (Sweden)

    Monika Anna Ameryk

    2017-02-01

    A correlation between the parents’ nutritional knowledge and the frequency of consumption of selected products by their children was observed. Parents with insufficient knowledge less frequently served dark bread and thick groats than those with good and sufficient knowledge. Parents with good and sufficient knowledge less frequently served instant soups, canned meat, energy and isotonic drinks. No impact of the parents’ knowledge was observed with reference to white cheese, vegetable oils and sweets. Nutritional education of the parents of young athletes is necessary regardless of their nutritional knowledge. Improving eating habits can positively affect children’s development and achievements in sports.   Keywords: Nutrition; Knowledge; Sport; Young Athletes; Eating habits.

  19. Selective visual scaling of time-scale processes facilitates broadband learning of isometric force frequency tracking.

    Science.gov (United States)

    King, Adam C; Newell, Karl M

    2015-10-01

    The experiment investigated the effect of selectively augmenting faster time scales of visual feedback information on the learning and transfer of continuous isometric force tracking tasks to test the generality of the self-organization of 1/f properties of force output. Three experimental groups tracked an irregular target pattern either under a standard fixed gain condition or with selectively enhancement in the visual feedback display of intermediate (4-8 Hz) or high (8-12 Hz) frequency components of the force output. All groups reduced tracking error over practice, with the error lowest in the intermediate scaling condition followed by the high scaling and fixed gain conditions, respectively. Selective visual scaling induced persistent changes across the frequency spectrum, with the strongest effect in the intermediate scaling condition and positive transfer to novel feedback displays. The findings reveal an interdependence of the timescales in the learning and transfer of isometric force output frequency structures consistent with 1/f process models of the time scales of motor output variability.

  20. Spatial Frequency Selectivity Is Impaired in Dopamine D2 Receptor Knockout Mice

    Science.gov (United States)

    Souza, Bruno Oliveira Ferreira; Abou Rjeili, Mira; Quintana, Clémentine; Beaulieu, Jean M.; Casanova, Christian

    2018-01-01

    Dopamine is a neurotransmitter implicated in several brain functions, including vision. In the present study, we investigated the impacts of the lack of D2 dopamine receptors on the structure and function of the primary visual cortex (V1) of D2-KO mice using optical imaging of intrinsic signals. Retinotopic maps were generated in order to measure anatomo-functional parameters such as V1 shape, cortical magnification factor, scatter, and ocular dominance. Contrast sensitivity and spatial frequency selectivity (SF) functions were computed from responses to drifting gratings. When compared to control mice, none of the parameters of the retinotopic maps were affected by D2 receptor loss of function. While the contrast sensitivity function of D2-KO mice did not differ from their wild-type counterparts, SF selectivity function was significantly affected as the optimal SF and the high cut-off frequency (p D2-KO than in WT mice. These findings show that the lack of function of D2 dopamine receptors had no influence on cortical structure whereas it had a significant impact on the spatial frequency selectivity and high cut-off. Taken together, our results suggest that D2 receptors play a specific role on the processing of spatial features in early visual cortex while they do not seem to participate in its development. PMID:29379422

  1. Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina

    Science.gov (United States)

    Williams, Lester J.; Dixon, Joann F.

    2015-01-01

    Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and other features in the aquifer system.

  2. Temperature dependency of cupular mechanics and hair cell frequency selectivity in the fish canal lateral line organ

    NARCIS (Netherlands)

    Wiersinga-Post, JEC; van Netten, SM

    2000-01-01

    The mechanical frequency selectivity of the cupula located in the supraorbital lateral line canal and the frequency selectivity of the hair cells driven by the cupula were measured simultaneously in vivo. Laser interferometry was used to measure cupular mechanics and extracellular receptor

  3. Effect of layer thickness in selective laser melting on microstructure of Al/5 wt.%Fe2O3 powder consolidated parts.

    Science.gov (United States)

    Dadbakhsh, Sasan; Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75  μm layer thickness, and 50  μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

  4. Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3 Powder Consolidated Parts

    Directory of Open Access Journals (Sweden)

    Sasan Dadbakhsh

    2014-01-01

    Full Text Available In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

  5. The film thickness dependent thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Xiudi; Xu Gang, E-mail: xiudixiao@163.com; Xiong Bin; Chen Deming; Miao Lei [Chinese Academy of Sciences, Key Laboratory of Renewable Energy and Gas Hydrates, Guangzhou Institute of Energy Conversion (China)

    2012-03-15

    The monolayer Al{sub 2}O{sub 3}:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing at 700 Degree-Sign C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration, and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles. On the base of film thickness results, the multilayer Al{sub 2}O{sub 3}:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 Degree-Sign C for 70 h in air. It can be concluded that film thickness is an important factor to control the thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers.

  6. Sound frequency and aural selectivity in sound-contingent visual motion aftereffect.

    Directory of Open Access Journals (Sweden)

    Maori Kobayashi

    Full Text Available BACKGROUND: One possible strategy to evaluate whether signals in different modalities originate from a common external event or object is to form associations between inputs from different senses. This strategy would be quite effective because signals in different modalities from a common external event would then be aligned spatially and temporally. Indeed, it has been demonstrated that after adaptation to visual apparent motion paired with alternating auditory tones, the tones begin to trigger illusory motion perception to a static visual stimulus, where the perceived direction of visual lateral motion depends on the order in which the tones are replayed. The mechanisms underlying this phenomenon remain unclear. One important approach to understanding the mechanisms is to examine whether the effect has some selectivity in auditory processing. However, it has not yet been determined whether this aftereffect can be transferred across sound frequencies and between ears. METHODOLOGY/PRINCIPAL FINDINGS: Two circles placed side by side were presented in alternation, producing apparent motion perception, and each onset was accompanied by a tone burst of a specific and unique frequency. After exposure to this visual apparent motion with tones for a few minutes, the tones became drivers for illusory motion perception. However, the aftereffect was observed only when the adapter and test tones were presented at the same frequency and to the same ear. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the auditory processing underlying the establishment of novel audiovisual associations is selective, potentially but not necessarily indicating that this processing occurs at an early stage.

  7. A General Model of Negative Frequency Dependent Selection Explains Global Patterns of Human ABO Polymorphism.

    Directory of Open Access Journals (Sweden)

    Fernando A Villanea

    Full Text Available The ABO locus in humans is characterized by elevated heterozygosity and very similar allele frequencies among populations scattered across the globe. Using knowledge of ABO protein function, we generated a simple model of asymmetric negative frequency dependent selection and genetic drift to explain the maintenance of ABO polymorphism and its loss in human populations. In our models, regardless of the strength of selection, models with large effective population sizes result in ABO allele frequencies that closely match those observed in most continental populations. Populations must be moderately small to fall out of equilibrium and lose either the A or B allele (N(e ≤ 50 and much smaller (N(e ≤ 25 for the complete loss of diversity, which nearly always involved the fixation of the O allele. A pattern of low heterozygosity at the ABO locus where loss of polymorphism occurs in our model is consistent with small populations, such as Native American populations. This study provides a general evolutionary model to explain the observed global patterns of polymorphism at the ABO locus and the pattern of allele loss in small populations. Moreover, these results inform the range of population sizes associated with the recent human colonization of the Americas.

  8. Human Commercial Models' Eye Colour Shows Negative Frequency-Dependent Selection.

    Directory of Open Access Journals (Sweden)

    Isabela Rodrigues Nogueira Forti

    Full Text Available In this study we investigated the eye colour of human commercial models registered in the UK (400 female and 400 male and Brazil (400 female and 400 male to test the hypothesis that model eye colour frequency was the result of negative frequency-dependent selection. The eye colours of the models were classified as: blue, brown or intermediate. Chi-square analyses of data for countries separated by sex showed that in the United Kingdom brown eyes and intermediate colours were significantly more frequent than expected in comparison to the general United Kingdom population (P<0.001. In Brazil, the most frequent eye colour brown was significantly less frequent than expected in comparison to the general Brazilian population. These results support the hypothesis that model eye colour is the result of negative frequency-dependent selection. This could be the result of people using eye colour as a marker of genetic diversity and finding rarer eye colours more attractive because of the potential advantage more genetically diverse offspring that could result from such a choice. Eye colour may be important because in comparison to many other physical traits (e.g., hair colour it is hard to modify, hide or disguise, and it is highly polymorphic.

  9. Frequency Tuning of IR First-Overtone CO Laser Radiation by Diffraction Grating and Frequency Selective Output Couplers

    National Research Council Canada - National Science Library

    Ionin, Andre

    1999-01-01

    ...: The contractor will investigate, both experimentally and theoretically, the feasibility of frequency tuning the first overtone carbon monoxide laser radiation by the use of diffraction gratings...

  10. A Method for Dynamically Selecting the Best Frequency Hopping Technique in Industrial Wireless Sensor Network Applications.

    Science.gov (United States)

    Fernández de Gorostiza, Erlantz; Berzosa, Jorge; Mabe, Jon; Cortiñas, Roberto

    2018-02-23

    Industrial wireless applications often share the communication channel with other wireless technologies and communication protocols. This coexistence produces interferences and transmission errors which require appropriate mechanisms to manage retransmissions. Nevertheless, these mechanisms increase the network latency and overhead due to the retransmissions. Thus, the loss of data packets and the measures to handle them produce an undesirable drop in the QoS and hinder the overall robustness and energy efficiency of the network. Interference avoidance mechanisms, such as frequency hopping techniques, reduce the need for retransmissions due to interferences but they are often tailored to specific scenarios and are not easily adapted to other use cases. On the other hand, the total absence of interference avoidance mechanisms introduces a security risk because the communication channel may be intentionally attacked and interfered with to hinder or totally block it. In this paper we propose a method for supporting the design of communication solutions under dynamic channel interference conditions and we implement dynamic management policies for frequency hopping technique and channel selection at runtime. The method considers several standard frequency hopping techniques and quality metrics, and the quality and status of the available frequency channels to propose the best combined solution to minimize the side effects of interferences. A simulation tool has been developed and used in this work to validate the method.

  11. Selective ablation of dental calculus with a frequency-doubled Alexandrite laser

    Science.gov (United States)

    Rechmann, Peter; Hennig, Thomas

    1996-01-01

    The aim of the study was the selective removal of dental calculus by means of pulsed lasers. In a first approach the optical characteristics of subgingival calculus were calculated using fluorescence emission spectroscopy (excitation laser: N2-laser, wavelength 337 nm, pulse duration 4 ns). Subgingival calculus seems to absorb highly in the ultraviolet spectral region up to 420 nm. According to these measurements a frequency doubled Alexandrite-laser (wavelength 377 nm, pulse duration 100 ns, repetition rate 110 Hz) was used to irradiate calculus located on enamel, at the cementum enamel junction and on the root surface (located on dentin or on cementum). Irradiation was performed perpendicular to the root surface with a laser fluence of 1 Jcm-2. During the irradiation procedure an effective water cooling-system was engaged. Histological investigations were done on undecalcified sections. As a result, engaging low fluences allows a fast and strictly selective removal of subgingival calculus. Even more the investigations revealed that supragingival calculus can be removed in a strictly selective manner engaging a frequency doubled Alexandrite-laser. No adverse side effects to the surrounding tissues could be found.

  12. Passive Frequency Selective Surface Array as a Diffuser for Destroying Millimeter Wave Coherence

    Directory of Open Access Journals (Sweden)

    Saiful Islam

    2008-01-01

    Full Text Available This paper presents the design, construction, and testing of grounded frequency selective surface (FSS array as a diffuser for destroying millimeter wave coherence which is used to eliminate speckle in active millimeter wave imaging. To create stochastically independent illumination patterns, we proposed a diffuser based on random-phase distributions obtained by changing the incident frequency. The random-phase diffuser was obtained by mixing up the phase relations between the cells of a deterministic function (e.g., beam splitter. The slot length of FSS is the main design parameter used to optimize the phase shifting properties of the array. The critical parameters of the diffuser array design, such as phase relation with slot lengths, losses, and bandwidth, are discussed. We designed the FSS arrays with finite integral technique (FIT, fabricated by etching technique, and characterized the S-parameters with a free-space MVNA, and measured the radiation patterns with a BWO in motorized setup.

  13. Analytical Solution for Elliptical Cloaks Based on The Frequency Selective Surface

    Directory of Open Access Journals (Sweden)

    E. Ghasemi Mizuji

    2015-01-01

    Full Text Available In this paper the elliptical dielectric cylinder which is covered with FSS cloak is considered. Frequency selective surface cloak which Alu named it mantle cloak is one of the recent techniques for cloaking. In this method an appropriate FSS can act as cloaking device for suppressing  the scattering of object  in the desired frequency. With using this method the dimension of the cloaks is extremely reduced. By this proposed structure, the RCS of elliptical cylinder  is reduced about 10-20 dB and designed cloak has an appropriate performance.  The analytical solution for the wave in each layer is presented and with using simulation, the electric field and the scattering pattern has been drawn.

  14. On the application of frequency selective common mode feedback for multifrequency EIT.

    Science.gov (United States)

    Langlois, Peter J; Wu, Yu; Bayford, Richard H; Demosthenous, Andreas

    2015-06-01

    Common mode voltages are frequently a problem in electrical impedance tomography (EIT) and other bioimpedance applications. To reduce their amplitude common mode feedback is employed. Formalised analyses of both current and voltage feedback is presented in this paper for current drives. Common mode effects due to imbalances caused by the current drives, the electrode connections to the body load and the introduction of the body impedance to ground are considered. Frequency selective narrowband common mode feedback previously proposed to provide feedback stability is examined. As a step towards multifrequency applications the use of narrowband feedback is experimentally demonstrated for two simultaneous current drives. Measured results using standard available components show a reduction of 62 dB for current feedback and 31 dB for voltage feedback. Frequencies ranged from 50 kHz to 1 MHz.

  15. A guinea pig model of selective severe high-frequency hearing loss.

    Science.gov (United States)

    Havenith, Sarah; Klis, Sjaak F L; Versnel, Huib; Grolman, Wilko

    2013-10-01

    Using an appropriate dose of an aminoglycoside antibiotic cotreated with a loop diuretic a guinea pig model of high-frequency loss can be obtained mimicking cochlear implant candidates with low-frequency residual hearing. We examined the stability of this model over time. A well-established method to create an animal model for profound deafness is cotreatment with an aminoglycoside antibiotic and a loop diuretic. Recent data indicated that reduction of the aminoglycoside dose might yield selective high-frequency hearing loss. Such a model is relevant for studies related to hybrid cochlear implant devices, for example, with respect to preservation of residual hearing. Guinea pigs received an electrode for chronic recording of compound action potentials to tones to assess thresholds. They were treated with a coadministration of kanamycin (200 mg/kg) and furosemide (100 mg/kg), after which, the animals were sacrificed for histologic analysis at 2, 4, or 7 weeks. After 2 to 7 weeks threshold shifts were greater than 50 dB for 8 to 16 kHz in 15 of 17 animals, whereas threshold shifts at 2 kHz or lower were less than 50 dB in 13 animals. Major threshold shifts occurred the first 2 to 4 days; subsequently, some spontaneous recovery occurred and, after 2-3 weeks thresholds, remained stable. Inner hair cell loss still progressed between 2 and 4 weeks in the most basal cochlear region; thereafter, hair cell loss was stable. An appropriate animal model for selective severe high-frequency hearing loss was obtained, which is stable at 4 weeks after ototoxic treatment.

  16. Optimized ONO thickness for multi-level and 2-bit/cell operation for wrapped-select-gate (WSG) SONOS memory

    International Nuclear Information System (INIS)

    Wu, Woei-Cherng; Chao, Tien-Sheng; Yang, Tsung-Yu; Peng, Wu-Chin; Yang, Wen-Luh; Chen, Jian-Hao; Ma, Ming Wen; Lai, Chao-Sung; Lee, Chien-Hsing; Hsieh, Tsung-Min; Liou, Jhyy Cheng; Chen, Tzu Ping; Chen, Chien Hung; Lin, Chih Hung; Chen, Hwi Huang; Ko, Joe

    2008-01-01

    In this paper, highly reliable wrapped-select-gate (WSG) silicon–oxide–nitride–oxide–silicon (SONOS) memory cells with multi-level and 2-bit/cell operation have been successfully demonstrated. The source-side injection mechanism for WSG-SONOS memory with different ONO thickness was thoroughly investigated. The different programming efficiencies of the WSG-SONOS memory under different ONO thicknesses are explained by the lateral electrical field extracted from the simulation results. Furthermore, multi-level storage is easily obtained, and good V TH distribution presented, for the WSG-SONOS memory with optimized ONO thickness. High program/erase speed (10 µs/5 ms) and low programming current (3.5 µA) are used to achieve the multi-level operation with tolerable gate and drain disturbance, negligible second-bit effect, excellent data retention and good endurance performance

  17. Equivalence of Linear MMSE Detection in DS-CDMA and MC-CDMA Systems over Time and Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Tamer A. Kadous

    2003-01-01

    Full Text Available The goal of this paper is to compare the performance of the linear minimum mean square error (MMSE detector for a class of code division multiple access (CDMA systems in time and frequency selective channels. Specifically, we consider direct sequence (DS-CDMA, multicarrier (MC-CDMA, and the MC-DS-CDMA systems. Two key tools are used in our development. First, a general time-frequency framework that includes the different CDMA systems as special cases. Second, the duality between time and frequency domains that is used to derive equivalences between the different CDMA systems operating over purely frequency selective and purely time selective channels. We then combine the insights obtained from these special cases to assess the performance of CDMA systems over time and frequency selective channels. We provide sufficient conditions for the codes employed by the CDMA systems for the equivalences to hold. Numerical results are presented to illustrate the results.

  18. Frequency-Selective Signal Sensing with Sub-Nyquist Uniform Sampling Scheme

    DEFF Research Database (Denmark)

    Pierzchlewski, Jacek; Arildsen, Thomas

    2015-01-01

    In this paper the authors discuss a problem of acquisition and reconstruction of a signal polluted by adjacent- channel interference. The authors propose a method to find a sub-Nyquist uniform sampling pattern which allows for correct reconstruction of selected frequencies. The method is inspired...... by the Restricted Isometry Property, which is known from the field of compressed sensing. Then, compressed sensing is used to successfully reconstruct a wanted signal even if some of the uniform samples were randomly lost, e. g. due to ADC saturation. An experiment which tests the proposed method in practice...

  19. Selective spleen scintigraphy to evaluate frequency of splenosis after posttraumatic splenectomy

    International Nuclear Information System (INIS)

    Loew, A.; Tischler, E.; Mahlstedt, J.; Wolf, F.; Meier, H.

    1981-01-01

    In 60 patients having had posttraumatic splenectomy between 9 months and 12 years ago frequency of splenosis was investigated in comparison to immunological and hematological parameters. Selective spleen scintigraphy was performed with sup(99m)-Tc-labelled heat-damaged auto-erythrocytes. In 46,7% of the patients splenosis was found without age dependence. Between patients with and without splenosis no significant differences concerning the immunological and hematological parameters were seen. Therefore, the lack of pathological manifestations after posttraumatic splenectomy is not to be related to autotransplantation of splenic tissue. (orig.) [de

  20. Guided wave mode selection for inhomogeneous elastic waveguides using frequency domain finite element approach.

    Science.gov (United States)

    Chillara, Vamshi Krishna; Ren, Baiyang; Lissenden, Cliff J

    2016-04-01

    This article describes the use of the frequency domain finite element (FDFE) technique for guided wave mode selection in inhomogeneous waveguides. Problems with Rayleigh-Lamb and Shear-Horizontal mode excitation in isotropic homogeneous plates are first studied to demonstrate the application of the approach. Then, two specific cases of inhomogeneous waveguides are studied using FDFE. Finally, an example of guided wave mode selection for inspecting disbonds in composites is presented. Identification of sensitive and insensitive modes for defect inspection is demonstrated. As the discretization parameters affect the accuracy of the results obtained from FDFE, effect of spatial discretization and the length of the domain used for the spatial fast Fourier transform are studied. Some recommendations with regard to the choice of the above parameters are provided. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Identification and association analysis of several hundred single nucleotide polymorphisms within candidate genes for back fat thickness in Italian Large White pigs using a selective genotyping approach.

    Science.gov (United States)

    Fontanesi, L; Galimberti, G; Calò, D G; Fronza, R; Martelli, P L; Scotti, E; Colombo, M; Schiavo, G; Casadio, R; Buttazzoni, L; Russo, V

    2012-08-01

    Combining different approaches (resequencing of portions of 54 obesity candidate genes, literature mining for pig markers associated with fat deposition or related traits in 77 genes, and in silico mining of porcine expressed sequence tags and other sequences available in databases), we identified and analyzed 736 SNP within candidate genes to identify markers associated with back fat thickness (BFT) in Italian Large White sows. Animals were chosen using a selective genotyping approach according to their EBV for BFT (276 with most negative and 279 with most positive EBV) within a population of ≈ 12,000 pigs. Association analysis between the SNP and BFT has been carried out using the MAX test proposed for case-control studies. The designed assays were successful for 656 SNP: 370 were excluded (low call rate or minor allele frequency A polymorphism (P(nominal) G polymorphism (P(nominal) = 8.0E-05). The third top SNP (P(nominal) = 6.2E-04) was the intronic TBC1D1 g.219G>A polymorphic site, in agreement with our previous results obtained in an independent study. The list of significant markers also included SNP in additional genes (ABHD16A, ABHD5, ACP2, ALMS1, APOA2, ATP1A2, CALR, COL14A1, CTSF, DARS, DECR1, ENPP1, ESR1, GH1, GHRL, GNMT, IKBKB, JAK3, MTTP, NFKBIA, NT5E, PLAT, PPARG, PPP2R5D, PRLR, RRAGD, RFC2, SDHD, SERPINF1, UBE2H, VCAM1, and WAT). Functional relationships between genes were obtained using the Ingenuity Pathway Analysis (IPA) Knowledge Base. The top scoring pathway included 19 genes with a P(nominal) < 0.1, 2 of which (IKBKB and NFKBIA) are involved in the hypothalamic IKKβ/NFκB program that could represent a key axis to affect fat deposition traits in pigs. These results represent a starting point to plan marker-assisted selection in Italian Large White nuclei for BFT. Because of similarities between humans and pigs, this study might also provide useful clues to investigate genetic factors affecting human obesity.

  2. Wideband RCS Reduction of Microstrip Array Antenna Based on Absorptive Frequency Selective Surface and Microstrip Resonators

    Directory of Open Access Journals (Sweden)

    Jingjing Xue

    2017-01-01

    Full Text Available An approach for wideband radar cross section (RCS reduction of a microstrip array antenna is presented and discussed. The scheme is based on the microstrip resonators and absorptive frequency selective surface (AFSS with a wideband absorptive property over the low band 1.9–7.5 GHz and a transmission characteristic at high frequency 11.05 GHz. The AFSS is designed to realize the out-of-band RCS reduction and preserve the radiation performance simultaneously, and it is placed above the antenna with the operating frequency of 11.05 GHz. Moreover, the microstrip resonators are loaded to obtain the in-band RCS reduction. As a result, a significant RCS reduction from 1.5 GHz to 13 GHz for both types of polarization has been accomplished. Compared with the reference antenna, the simulated results exhibit that the monostatic RCS of the proposed array antenna in x- and y-polarization can be reduced as much as 17.6 dB and 21.5 dB, respectively. And the measured results agree well with the simulated ones.

  3. Diversity Techniques for Single-Carrier Packet Retransmissions over Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Assimi Abdel-Nasser

    2009-01-01

    Full Text Available In data packet communication systems over multipath frequency-selective channels, hybrid automatic repeat request (HARQ protocols are usually used in order to ensure data reliability. For single-carrier packet transmission in slow fading environment, an identical retransmission of the same packet, due to a decoding failure, does not fully exploit the available time diversity in retransmission-based HARQ protocols. In this paper, we compare two transmit diversity techniques, namely, cyclic frequency-shift diversity and bit-interleaving diversity. Both techniques can be integrated in the HARQ scheme in order to improve the performance of the joint detector. Their performance in terms of pairwise error probability is investigated using maximum likelihood detection and decoding. The impact of the channel memory and the modulation order on the performance gain is emphasized. In practice, we use low complexity linear filter-based equalization which can be efficiently implemented in the frequency domain. The use of iterative equalization and decoding is also considered. The performance gain in terms of frame error rate and data throughput is evaluated by numerical simulations.

  4. Video error concealment using block matching and frequency selective extrapolation algorithms

    Science.gov (United States)

    P. K., Rajani; Khaparde, Arti

    2017-06-01

    Error Concealment (EC) is a technique at the decoder side to hide the transmission errors. It is done by analyzing the spatial or temporal information from available video frames. It is very important to recover distorted video because they are used for various applications such as video-telephone, video-conference, TV, DVD, internet video streaming, video games etc .Retransmission-based and resilient-based methods, are also used for error removal. But these methods add delay and redundant data. So error concealment is the best option for error hiding. In this paper, the error concealment methods such as Block Matching error concealment algorithm is compared with Frequency Selective Extrapolation algorithm. Both the works are based on concealment of manually error video frames as input. The parameter used for objective quality measurement was PSNR (Peak Signal to Noise Ratio) and SSIM(Structural Similarity Index). The original video frames along with error video frames are compared with both the Error concealment algorithms. According to simulation results, Frequency Selective Extrapolation is showing better quality measures such as 48% improved PSNR and 94% increased SSIM than Block Matching Algorithm.

  5. Switches of stimulus tagging frequencies interact with the conflict-driven control of selective attention, but not with inhibitory control.

    Science.gov (United States)

    Scherbaum, Stefan; Frisch, Simon; Dshemuchadse, Maja

    2016-01-01

    Selective attention and its adaptation by cognitive control processes are considered a core aspect of goal-directed action. Often, selective attention is studied behaviorally with conflict tasks, but an emerging neuroscientific method for the study of selective attention is EEG frequency tagging. It applies different flicker frequencies to the stimuli of interest eliciting steady state visual evoked potentials (SSVEPs) in the EEG. These oscillating SSVEPs in the EEG allow tracing the allocation of selective attention to each tagged stimulus continuously over time. The present behavioral investigation points to an important caveat of using tagging frequencies: The flicker of stimuli not only produces a useful neuroscientific marker of selective attention, but interacts with the adaptation of selective attention itself. Our results indicate that RT patterns of adaptation after response conflict (so-called conflict adaptation) are reversed when flicker frequencies switch at once. However, this effect of frequency switches is specific to the adaptation by conflict-driven control processes, since we find no effects of frequency switches on inhibitory control processes after no-go trials. We discuss the theoretical implications of this finding and propose precautions that should be taken into account when studying conflict adaptation using frequency tagging in order to control for the described confounds. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Retail Deli Slicer Cleaning Frequency--Six Selected Sites, United States, 2012.

    Science.gov (United States)

    Brown, Laura G; Hoover, E Rickamer; Ripley, Danny; Matis, Bailey; Nicholas, David; Hedeen, Nicole; Faw, Brenda

    2016-04-01

    Listeria monocytogenes (Listeria) causes the third highest number of foodborne illness deaths (an estimated 255) in the United States annually, after nontyphoidal Salmonella species and Toxoplasma gondii (1). Deli meats are a major source of listeriosis illnesses, and meats sliced and packaged at retail delis are the major source of listeriosis illnesses attributed to deli meat (4). Mechanical slicers pose cross-contamination risks in delis and are an important source of Listeria cross-contamination. Reducing Listeria contamination of sliced meats in delis will likely reduce Listeria illnesses and outbreaks. Good slicer cleaning practices can reduce this foodborne illness risk. CDC's Environmental Health Specialists Network (EHS-Net) studied how often retail deli slicers were fully cleaned (disassembled, cleaned, and sanitized) at the Food and Drug Administration (FDA) Food Code-specified minimum frequency of every 4 hours and examined deli and staff characteristics related to slicer cleaning frequency. Interviews with staff members in 298 randomly-selected delis in six EHS-Net sites showed that approximately half of delis fully cleaned their slicers less often than FDA's specified minimum frequency. Chain-owned delis and delis with more customers, more slicers, required manager food safety training, food safety-knowledgeable workers, written slicer-cleaning policies, and food safety-certified managers fully cleaned their slicers more frequently than did other types of delis, according to deli managers or workers. States and localities should require deli manager training and certification, as specified in the FDA Food Code. They should also consider encouraging or requiring delis to have written slicer-cleaning policies. Retail food industry leaders can also implement these prevention efforts to reduce risk in their establishments. Because independent and smaller delis had lower frequencies of slicer cleaning, prevention efforts should focus on these types of

  7. Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

    Science.gov (United States)

    Manurkar, Paritosh

    Most of the existing protocols for quantum communication operate in a two-dimensional Hilbert space where their manipulation and measurement have been routinely investigated. Moving to higher-dimensional Hilbert spaces is desirable because of advantages in terms of longer distance communication capabilities, higher channel capacity and better information security. We can exploit the spatio-temporal degrees of freedom for the quantum optical signals to provide the higher-dimensional signals. But this necessitates the need for measurement and manipulation of multidimensional quantum states. To that end, there have been significant theoretical studies based on quantum frequency conversion (QFC) in recent years even though the experimental progress has been limited. QFC is a process that allows preservation of the quantum information while changing the frequency of the input quantum state. It has deservedly garnered a lot of attention because it serves as the connecting bridge between the communications band (C-band near 1550 nm) where the fiber-optic infrastructure is already established and the visible spectrum where high efficiency single-photon detectors and optical memories have been demonstrated. In this experimental work, we demonstrate mode-selective frequency conversion as a means to measure and manipulate photonic signals occupying d -dimensional Hilbert spaces where d=2 and 4. In the d=2 case, we demonstrate mode contrast between two temporal modes (TMs) which serves as the proof-of-concept demonstration. In the d=4 version, we employ six different TMs for our detailed experimental study. These TMs also include superposition modes which are a crucial component in many quantum key distribution protocols. Our method is based on producing pump pulses which allow us to upconvert the TM of interest while ideally preserving the other modes. We use MATLAB simulations to determine the pump pulse shapes which are subsequently produced by controlling the amplitude and

  8. Host population structure and treatment frequency maintain balancing selection on drug resistance

    Science.gov (United States)

    Baskerville, Edward B.; Colijn, Caroline; Hanage, William; Fraser, Christophe; Lipsitch, Marc

    2017-01-01

    It is a truism that antimicrobial drugs select for resistance, but explaining pathogen- and population-specific variation in patterns of resistance remains an open problem. Like other common commensals, Streptococcus pneumoniae has demonstrated persistent coexistence of drug-sensitive and drug-resistant strains. Theoretically, this outcome is unlikely. We modelled the dynamics of competing strains of S. pneumoniae to investigate the impact of transmission dynamics and treatment-induced selective pressures on the probability of stable coexistence. We find that the outcome of competition is extremely sensitive to structure in the host population, although coexistence can arise from age-assortative transmission models with age-varying rates of antibiotic use. Moreover, we find that the selective pressure from antibiotics arises not so much from the rate of antibiotic use per se but from the frequency of treatment: frequent antibiotic therapy disproportionately impacts the fitness of sensitive strains. This same phenomenon explains why serotypes with longer durations of carriage tend to be more resistant. These dynamics may apply to other potentially pathogenic, microbial commensals and highlight how population structure, which is often omitted from models, can have a large impact. PMID:28835542

  9. Improved CT-detection of acute bowel ischemia using frequency selective non-linear image blending.

    Science.gov (United States)

    Schneeweiss, Sven; Esser, Michael; Thaiss, Wolfgang; Boesmueller, Hans; Ditt, Hendrik; Nikolau, Konstantin; Horger, Marius

    2017-07-01

    Computed tomography (CT) as a fast and reliable diagnostic technique is the imaging modality of choice for acute bowel ischemia. However, diagnostic is often difficult mainly due to low attenuation differences between ischemic and perfused segments. To compare the diagnostic efficacy of a new post-processing tool based on frequency selective non-linear blending with that of conventional linear contrast-enhanced CT (CECT) image blending for the detection of bowel ischemia. Twenty-seven consecutive patients (19 women; mean age = 73.7 years, age range = 50-94 years) with acute bowel ischemia were scanned using multidetector CT (120 kV; 100-200 mAs). Pre-contrast and portal venous scans (65-70 s delay) were acquired. All patients underwent surgery for acute bowel ischemia and intraoperative diagnosis as well as histologic evaluation of explanted bowel segments was considered "gold standard." First, two radiologists read the conventional CECT images in which linear blending was adapted for optimal contrast, and second (three weeks later) the frequency selective non-linear blending (F-NLB) image. Attenuation values were compared, both in the involved and non-involved bowel segments creating ratios between unenhanced and CECT. The mean attenuation difference between ischemic and non-ischemic wall in the portal venous scan was 69.54 HU (reader 2 = 69.01 HU) higher for F-NLB compared with conventional CECT. Also, the attenuation ratio between contrast-enhanced and pre-contrast CT data for the non-ischemic walls showed significantly higher values for the F-NLB image (CECT: reader 1 = 2.11 (reader 2 = 3.36), F-NLB: reader 1 = 4.46 (reader 2 = 4.98)]. Sensitivity in detecting ischemic areas increased significantly for both readers using F-NLB (CECT: reader 1/2 = 53%/65% versus F-NLB: reader 1/2 = 62%/75%). Frequency selective non-linear blending improves detection of bowel ischemia compared with conventional CECT by increasing

  10. All-dielectric metamaterial frequency selective surface based on spatial arrangement ceramic resonators

    Science.gov (United States)

    Li, Liyang; Wang, Jun; Feng, Mingde; Ma, Hua; Wang, Jiafu; Du, Hongliang; Qu, Shaobo

    In this paper, we demonstrate a method of designing all-dielectric metamaterial frequency selective surface (FSS) with ceramic resonators in spatial arrangement. Compared with the traditional way, spatial arrangement provides a flexible way to handle the permutation and combination of different ceramic resonators. With this method, the resonance response can be adjusted easily to achieve pass/stop band effects. As an example, a stop band spatial arrangement all-dielectric metamaterial FSS is designed. Its working band is in 11.65-12.23GHz. By adjusting permittivity and geometrical parameters of ceramic resonators, we can easily modulate the resonances, band pass or band stop characteristic, as well as the working band.

  11. Characteristic of selected frequency luminescence for paleo-debris flow deposits in Jiangjia valley

    International Nuclear Information System (INIS)

    Liu Zhaowen; Wei Mingjian; Pan Baolin; Liu Chao; Li Dongxu

    2008-01-01

    Eight paleo-debris flow samples from Nideping, Duozhao, Dawazi valley, and Jiangjia valley in Yunnan Province were tested with BG2003 luminescence spectrograph. The characteristic spectra of the selected frequency luminescence of paleo-debris flow deposits from the different locations were obtained. Excited at 488 nm, the wavelengths of emission photons from all samples are 300, 310, 320, 400 and 460 nm. With green excitation (532 nm), the wavelengths of emission photons from all samples are 300, 310, 320 and 460 nm. Then it is determined that the luminescence spectrographs of Nideping are almost same in different time, however, they are different in Dawazi valley and Duozhao. Taking Nideping for example, excited at green, the debris flow substances from the upper, middle, or lower zone of this platform. Response to increasing irradiation dose at 310, 320, and 460 nm, we can define the wavelengths used for dating. (authors)

  12. A Comparison Between Jerusalem Cross and Square Patch Frequency Selective Surfaces for Low Profile Antenna Applications

    Science.gov (United States)

    Cure, David; Weller, Thomas; Miranda, Felix A.

    2011-01-01

    In this paper, a comparison between Jerusalem Cross (JC) and Square Patch (SP) based Frequency Selected Surfaces (FSS) for low profile antenna applications is presented. The comparison is aimed at understanding the performance of low profile antennas backed by high impedance surfaces. In particular, an end loaded planar open sleeve dipole (ELPOSD) antenna is examined due to the various parameters within its configuration, offering significant design flexibility and a wide operating bandwidth. Measured data of the antennas demonstrate that increasing the number of unit cells improves the fractional bandwidth. The antenna bandwidth increased from 0.8% to 1.8% and from 0.8% to 2.7% for the JC and SP structures, respectively. The number of unit cells was increased from 48 to 80 for the JC-FSS and from 24 to 48 for the SP-FSS.

  13. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.; Ahimian, Nariman R.; Alouini, Mohamed-Slim

    2010-01-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  14. Sibling genes as environment: Sibling dopamine genotypes and adolescent health support frequency dependent selection.

    Science.gov (United States)

    Rauscher, Emily; Conley, Dalton; Siegal, Mark L

    2015-11-01

    While research consistently suggests siblings matter for individual outcomes, it remains unclear why. At the same time, studies of genetic effects on health typically correlate variants of a gene with the average level of behavioral or health measures, ignoring more complicated genetic dynamics. Using National Longitudinal Study of Adolescent Health data, we investigate whether sibling genes moderate individual genetic expression. We compare twin variation in health-related absences and self-rated health by genetic differences at three locations related to dopamine regulation and transport to test sibship-level cross-person gene-gene interactions. Results suggest effects of variation at these genetic locations are moderated by sibling genes. Although the mechanism remains unclear, this evidence is consistent with frequency dependent selection and suggests much genetic research may violate the stable unit treatment value assumption. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. A preliminary research of characteristic of selected frequency luminescence for debris flow in Jiangjiagou valley

    International Nuclear Information System (INIS)

    Liu Zhaowen; Wei Mingjian; Li Dongxu; Pan Baolin; Ge Yonggang

    2009-01-01

    Four debris flow samples were separated from Nidepin, Duozhao and Dawazigou valleys in Jiangjiagou valley area, Yunnan province. They were measured with BG2003 luminescence spectrograph. The characteristic spectra of the selected frequency luminescence of samples from the different locations were obtained. The wave length of emission photons from samples of Dawazigou valley and Jiangjia valley are 300, 310, 320, 400 and 460 nm when it was using blue light (488)nm excited. When the green light (532 nm) has been used to excited, the wave length of emission photons from samples of Dawazigou valley and Duozhao valley are similar high at 310 and 320 nm. Furthermore, using the green light excited the samples from desert sand at the same lab condition; the number of absorbed photons of samples from desert sand is much higher than from debris flow. (authors)

  16. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.

    2010-09-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  17. Fine-structure processing, frequency selectivity and speech perception in hearing-impaired listeners

    DEFF Research Database (Denmark)

    Strelcyk, Olaf; Dau, Torsten

    2008-01-01

    Hearing-impaired people often experience great difficulty with speech communication when background noise is present, even if reduced audibility has been compensated for. Other impairment factors must be involved. In order to minimize confounding effects, the subjects participating in this study...... consisted of groups with homogeneous, symmetric audiograms. The perceptual listening experiments assessed the intelligibility of full-spectrum as well as low-pass filtered speech in the presence of stationary and fluctuating interferers, the individual's frequency selectivity and the integrity of temporal...... modulation were obtained. In addition, these binaural and monaural thresholds were measured in a stationary background noise in order to assess the persistence of the fine-structure processing to interfering noise. Apart from elevated speech reception thresholds, the hearing impaired listeners showed poorer...

  18. Low-Complexity Iterative Receiver for Space-Time Coded Signals over Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Mohamed Siala

    2002-05-01

    Full Text Available We propose a low-complexity turbo-detector scheme for frequency selective multiple-input multiple-output channels. The detection part of the receiver is based on a List-type MAP equalizer which is a state-reduction algorithm of the MAP algorithm using per-survivor technique. This alternative achieves a good tradeoff between performance and complexity provided a small amount of the channel is neglected. In order to induce the good performance of this equalizer, we propose to use a whitened matched filter (WMF which leads to a white-noise “minimum phase” channel model. Simulation results show that the use of the WMF yields significant improvement, particularly over severe channels. Thanks to the iterative turbo processing (detection and decoding are iterated several times, the performance loss due to the use of the suboptimum List-type equalizer is recovered.

  19. Effect of catchment properties and flood generation regime on copula selection for bivariate flood frequency analysis

    Science.gov (United States)

    Filipova, Valeriya; Lawrence, Deborah; Klempe, Harald

    2018-02-01

    Applying copula-based bivariate flood frequency analysis is advantageous because the results provide information on both the flood peak and volume. More data are, however, required for such an analysis, and it is often the case that only data series with a limited record length are available. To overcome this issue of limited record length, data regarding climatic and geomorphological properties can be used to complement statistical methods. In this paper, we present a study of 27 catchments located throughout Norway, in which we assess whether catchment properties, flood generation processes and flood regime have an effect on the correlation between flood peak and volume and, in turn, on the selection of copulas. To achieve this, the annual maximum flood events were first classified into events generated primarily by rainfall, snowmelt or a combination of these. The catchments were then classified into flood regime, depending on the predominant flood generation process producing the annual maximum flood events. A contingency table and Fisher's exact test were used to determine the factors that affect the selection of copulas in the study area. The results show that the two-parameter copulas BB1 and BB7 are more commonly selected in catchments with high steepness, high mean annual runoff and rainfall flood regime. These findings suggest that in these types of catchments, the dependence structure between flood peak and volume is more complex and cannot be modeled effectively using a one-parameter copula. The results illustrate that by relating copula types to flood regime and catchment properties, additional information can be supplied for selecting copulas in catchments with limited data.

  20. Frequency selective surface based passive wireless sensor for structural health monitoring

    International Nuclear Information System (INIS)

    Jang, Sang-Dong; Kang, Byung-Woo; Kim, Jaehwan

    2013-01-01

    Wireless sensor networks or ubiquitous sensor networks are a promising technology giving useful information to people. In particular, the chipless passive wireless sensor is one of the most important developments in wireless sensor technology because it is compact and does not need a battery or chip for the sensor operation. So it has many possibilities for use in various types of sensor system with economical efficiency and robustness in harsh environmental conditions. This sensor uses an electromagnetic resonance frequency or phase angle shift associated with a geometrical change of the sensor tag or an impedance change of the sensor. In this paper, a chipless passive wireless structural health monitoring (SHM) sensor is made using a frequency selective surface (FSS). The cross type FSS is introduced, and its SHM principle is explained. The electromagnetic characteristics of the FSS are simulated in terms of transmission and reflection coefficients using simulation software, and an experimental verification is conducted. The electromagnetic characteristic change of the FSS in the presence of mechanical strain or a structural crack is investigated by means of simulation and experiment. Since large-area structures can be covered by deploying FSS, it is possible to detect the location of any cracks. (paper)

  1. Analysis and applications of a frequency selective surface via a random distribution method

    International Nuclear Information System (INIS)

    Xie Shao-Yi; Huang Jing-Jian; Yuan Nai-Chang; Liu Li-Guo

    2014-01-01

    A novel frequency selective surface (FSS) for reducing radar cross section (RCS) is proposed in this paper. This FSS is based on the random distribution method, so it can be called random surface. In this paper, the stacked patches serving as periodic elements are employed for RCS reduction. Previous work has demonstrated the efficiency by utilizing the microstrip patches, especially for the reflectarray. First, the relevant theory of the method is described. Then a sample of a three-layer variable-sized stacked patch random surface with a dimension of 260 mm×260 mm is simulated, fabricated, and measured in order to demonstrate the validity of the proposed design. For the normal incidence, the 8-dB RCS reduction can be achieved both by the simulation and the measurement in 8 GHz–13 GHz. The oblique incidence of 30° is also investigated, in which the 7-dB RCS reduction can be obtained in a frequency range of 8 GHz–14 GHz. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Blind CP-OFDM and ZP-OFDM Parameter Estimation in Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    Vincent Le Nir

    2009-01-01

    Full Text Available A cognitive radio system needs accurate knowledge of the radio spectrum it operates in. Blind modulation recognition techniques have been proposed to discriminate between single-carrier and multicarrier modulations and to estimate their parameters. Some powerful techniques use autocorrelation- and cyclic autocorrelation-based features of the transmitted signal applying to OFDM signals using a Cyclic Prefix time guard interval (CP-OFDM. In this paper, we propose a blind parameter estimation technique based on a power autocorrelation feature applying to OFDM signals using a Zero Padding time guard interval (ZP-OFDM which in particular excludes the use of the autocorrelation- and cyclic autocorrelation-based techniques. The proposed technique leads to an efficient estimation of the symbol duration and zero padding duration in frequency selective channels, and is insensitive to receiver phase and frequency offsets. Simulation results are given for WiMAX and WiMedia signals using realistic Stanford University Interim (SUI and Ultra-Wideband (UWB IEEE 802.15.4a channel models, respectively.

  3. Multi-year high-frequency hydrothermal monitoring of selected high-threat Cascade Range volcanoes

    Science.gov (United States)

    Crankshaw, I. M.; Archfield, S. A.; Newman, A. C.; Bergfeld, D.; Clor, L. E.; Spicer, K. R.; Kelly, P. J.; Evans, W. C.; Ingebritsen, S. E.

    2018-05-01

    From 2009 to 2015 the U.S. Geological Survey (USGS) systematically monitored hydrothermal behavior at selected Cascade Range volcanoes in order to define baseline hydrothermal and geochemical conditions. Gas and water data were collected regularly at 25 sites on 10 of the highest-risk volcanoes in the Cascade Range. These sites include near-summit fumarole groups and springs/streams that show clear evidence of magmatic influence (high 3He/4He ratios and/or large fluxes of magmatic CO2 or heat). Site records consist mainly of hourly temperature and hydrothermal-flux data. Having established baseline conditions during a multiyear quiescent period, the USGS reduced monitoring frequency from 2015 to present. The archived monitoring data are housed at (doi:10.5066/F72N5088). These data (1) are suitable for retrospective comparison with other continuous geophysical monitoring data and (2) will provide context during future episodes of volcanic unrest, such that unrest-related variations at these thoroughly characterized sites will be more clearly recognizable. Relatively high-frequency year-round data are essential to achieve these objectives, because many of the time series reveal significant diurnal, seasonal, and inter-annual variability that would tend to mask unrest signals in the absence of baseline data. Here we characterize normal variability for each site, suggest strategies to detect future volcanic unrest, and explore deviations from background associated with recent unrest.

  4. Selective Interareal Synchronization through Gamma Frequency Differences and Slower-Rhythm Gamma Phase Reset.

    Science.gov (United States)

    Burwick, Thomas; Bouras, Alexandros

    2017-03-01

    The communication-through-coherence (CTC) hypothesis states that a sending group of neurons will have a particularly strong effect on a receiving group if both groups oscillate in a phase-locked ("coherent") manner (Fries, 2005 , 2015 ). Here, we consider a situation with two visual stimuli, one in the focus of attention and the other distracting, resulting in two sites of excitation at an early cortical area that project to a common site in a next area. Taking a modeler's perspective, we confirm the workings of a mechanism that was proposed by Bosman et al. ( 2012 ) in the context of providing experimental evidence for the CTC hypothesis: a slightly higher gamma frequency of the attended sending site compared to the distracting site may cause selective interareal synchronization with the receiving site if combined with a slow-rhythm gamma phase reset. We also demonstrate the relevance of a slightly lower intrinsic frequency of the receiving site for this scenario. Moreover, we discuss conditions for a transition from bottom-up to top-down driven phase locking.

  5. Spatial heterogeneity, frequency-dependent selection and polymorphism in host-parasite interactions

    Directory of Open Access Journals (Sweden)

    Tellier Aurélien

    2011-11-01

    Full Text Available Abstract Background Genomic and pathology analysis has revealed enormous diversity in genes involved in disease, including those encoding host resistance and parasite effectors (also known in plant pathology as avirulence genes. It has been proposed that such variation may persist when an organism exists in a spatially structured metapopulation, following the geographic mosaic of coevolution. Here, we study gene-for-gene relationships governing the outcome of plant-parasite interactions in a spatially structured system and, in particular, investigate the population genetic processes which maintain balanced polymorphism in both species. Results Following previous theory on the effect of heterogeneous environments on maintenance of polymorphism, we analysed a model with two demes in which the demes have different environments and are coupled by gene flow. Environmental variation is manifested by different coefficients of natural selection, the costs to the host of resistance and to the parasite of virulence, the cost to the host of being diseased and the cost to an avirulent parasite of unsuccessfully attacking a resistant host. We show that migration generates negative direct frequency-dependent selection, a condition for maintenance of stable polymorphism in each deme. Balanced polymorphism occurs preferentially if there is heterogeneity for costs of resistance and virulence alleles among populations and to a lesser extent if there is variation in the cost to the host of being diseased. We show that the four fitness costs control the natural frequency of oscillation of host resistance and parasite avirulence alleles. If demes have different costs, their frequencies of oscillation differ and when coupled by gene flow, there is amplitude death of the oscillations in each deme. Numerical simulations show that for a multiple deme island model, costs of resistance and virulence need not to be present in each deme for stable polymorphism to occur

  6. Fatigue level estimation of monetary bills based on frequency band acoustic signals with feature selection by supervised SOM

    Science.gov (United States)

    Teranishi, Masaru; Omatu, Sigeru; Kosaka, Toshihisa

    Fatigued monetary bills adversely affect the daily operation of automated teller machines (ATMs). In order to make the classification of fatigued bills more efficient, the development of an automatic fatigued monetary bill classification method is desirable. We propose a new method by which to estimate the fatigue level of monetary bills from the feature-selected frequency band acoustic energy pattern of banking machines. By using a supervised self-organizing map (SOM), we effectively estimate the fatigue level using only the feature-selected frequency band acoustic energy pattern. Furthermore, the feature-selected frequency band acoustic energy pattern improves the estimation accuracy of the fatigue level of monetary bills by adding frequency domain information to the acoustic energy pattern. The experimental results with real monetary bill samples reveal the effectiveness of the proposed method.

  7. Optimized aspect ratios of restrained thick-wall cylinders by virtue of Poisson's ratio selection. Part two: Temperature application

    International Nuclear Information System (INIS)

    Whitty, J.P.M.; Henderson, B.; Francis, J.

    2011-01-01

    Highlights: → Incontrovertible evidence is presented that thermal stresses in cylindrical components which include nuclear reactors and containment vessels are shown to be highly dependent on the Poisson's ratio of the materials. → The key novelty is concerned with the identification of a new potential thermal applications for negative Poisson's ratio (auxetic) materials; i.e. those that get fatter when they are stretched. → Negative Poisson's ratio (auxetic) materials exhibit lower thermal stress build-up than conventional positive Poisson's ratio materials, this conjecture being proven using thermal surface plots. - Abstract: Analytical and numerical modelling have been employed to show that the choice of Poisson's ratio is one of the principal design criteria in order to reduce thermal stress build-up in isotropic materials. The modelling procedures are all twofold; consisting of a solution to a steady-state heat conduction problem followed by a linear static solution. The models developed take the form of simplistic thick-wall cylinders such model systems are applicable at macro-structural and micro-structural levels as the underlining formulations are based on the classical theory of elasticity. Generally, the results show that the Poisson's ratio of the material has a greater effect on the magnitude of the principal stresses than the aspect ratio of the cylinders investigated. Constraining the outside of these models significantly increases the thermal stresses induced. The most significant and original finding presented is that the for both freely expanding and constrained thick-wall cylinders the optimum Poisson's ratio is minus unity.

  8. Frequency Selective Non-Linear Blending to Improve Image Quality in Liver CT.

    Science.gov (United States)

    Bongers, M N; Bier, G; Kloth, C; Schabel, C; Fritz, J; Nikolaou, K; Horger, M

    2016-12-01

    Purpose: To evaluate the effects of a new frequency selective non-linear blending (NLB) algorithm on the contrast resolution of liver CT with low intravascular concentration of iodine contrast. Materials and Methods: Our local ethics committee approved this retrospective study. The informed consent requirement was waived. CT exams of 25 patients (60 % female, mean age: 65 ± 16 years of age) with late phase CT scans of the liver were included as a model for poor intrahepatic vascular contrast enhancement. Optimal post-processing settings to enhance the contrast of hepatic vessels were determined. Outcome variables included signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of hepatic vessels and SNR of liver parenchyma of standard and post-processed images. Image quality was quantified by two independent readers using Likert scales. Results: The post-processing settings for the visualization of hepatic vasculature were optimal at a center of 115HU, delta of 25HU, and slope of 5. Image noise was statistically indifferent between standard and post-processed images. The CNR between the hepatic vasculature (HV) and liver parenchyma could be significantly increased for liver veins (CNR Standard 1.62 ± 1.10, CNR NLB 3.6 ± 2.94, p = 0.0002) and portal veins (CNR Standard 1.31 ± 0.85, CNR NLB 2.42 ± 3.03, p = 0.046). The SNR of liver parenchyma was significantly higher on post-processed images (SNR NLB 11.26 ± 3.16, SNR Standard 8.85 ± 2.27, p = 0.008). The overall image quality and depiction of HV were significantly higher on post-processed images (NLB DHV : 4 [3 - 4.75], S tandardDHV : 2 [1.3 - 2.5], p = algorithm increases the contrast resolution of liver CT and can improve the visibility of the hepatic vasculature in the setting of a low contrast ratio between vessels and the parenchyma. Key Points: • Using the new frequency selective non-linear blending algorithm is feasible in contrast

  9. Frequency selective non-linear blending to improve image quality in liver CT

    International Nuclear Information System (INIS)

    Bongers, M.N.; Bier, G.; Kloth, C.; Schabel, C.; Nikolaou, K.; Horger, M.; Fritz, J.

    2016-01-01

    To evaluate the effects of a new frequency selective non-linear blending (NLB) algorithm on the contrast resolution of liver CT with low intravascular concentration of iodine contrast. Our local ethics committee approved this retrospective study. The informed consent requirement was waived. CT exams of 25 patients (60% female, mean age: 65±16 years of age) with late phase CT scans of the liver were included as a model for poor intrahepatic vascular contrast enhancement. Optimal post-processing settings to enhance the contrast of hepatic vessels were determined. Outcome variables included signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of hepatic vessels and SNR of liver parenchyma of standard and post-processed images. Image quality was quantified by two independent readers using Likert scales. The post-processing settings for the visualization of hepatic vasculature were optimal at a center of 115HU, delta of 25HU, and slope of 5. Image noise was statistically indifferent between standard and post-processed images. The CNR between the hepatic vasculature (HV) and liver parenchyma could be significantly increased for liver veins (CNR Standard 1.62±1.10, CNR NLB 3.6±2.94, p=0.0002) and portal veins (CNR Standard 1.31±0.85, CNR NLB 2.42±3.03, p=0.046). The SNR of liver parenchyma was significantly higher on post-processed images (SNR NLB 11.26±3.16, SNR Standard 8.85± 2.27, p=0.008). The overall image quality and depiction of HV were significantly higher on post-processed images (NLB DHV : 4 [3-4.75], S tandardDHV : 2 [1.3-2.5], p=<0.0001; NLBIQ : 4 [4-4], StandardIQ : 2 [2-3], p=<0.0001). The use of a frequency selective non-linear blending algorithm increases the contrast resolution of liver CT and can improve the visibility of the hepatic vasculature in the setting of a low contrast ratio between vessels and the parenchyma.

  10. Frequency selective non-linear blending to improve image quality in liver CT

    Energy Technology Data Exchange (ETDEWEB)

    Bongers, M.N.; Bier, G.; Kloth, C.; Schabel, C.; Nikolaou, K.; Horger, M. [University Hospital of Tuebingen (Germany). Dept. of Diagnostic and Interventional Radiology; Fritz, J. [Johns Hopkins University School of Medicine, Baltimore, MD (United States). Russell H. Morgan Dept. of Radiology and Radiological Science

    2016-12-15

    To evaluate the effects of a new frequency selective non-linear blending (NLB) algorithm on the contrast resolution of liver CT with low intravascular concentration of iodine contrast. Our local ethics committee approved this retrospective study. The informed consent requirement was waived. CT exams of 25 patients (60% female, mean age: 65±16 years of age) with late phase CT scans of the liver were included as a model for poor intrahepatic vascular contrast enhancement. Optimal post-processing settings to enhance the contrast of hepatic vessels were determined. Outcome variables included signal-to-noise (SNR) and contrast-to-noise ratios (CNR) of hepatic vessels and SNR of liver parenchyma of standard and post-processed images. Image quality was quantified by two independent readers using Likert scales. The post-processing settings for the visualization of hepatic vasculature were optimal at a center of 115HU, delta of 25HU, and slope of 5. Image noise was statistically indifferent between standard and post-processed images. The CNR between the hepatic vasculature (HV) and liver parenchyma could be significantly increased for liver veins (CNR{sub Standard} 1.62±1.10, CNR{sub NLB} 3.6±2.94, p=0.0002) and portal veins (CNR{sub Standard} 1.31±0.85, CNR{sub NLB} 2.42±3.03, p=0.046). The SNR of liver parenchyma was significantly higher on post-processed images (SNR{sub NLB} 11.26±3.16, SNR{sub Standard} 8.85± 2.27, p=0.008). The overall image quality and depiction of HV were significantly higher on post-processed images (NLB{sub DHV}: 4 [3-4.75], S{sub tandardDHV}: 2 [1.3-2.5], p=<0.0001; {sub NLBIQ}: 4 [4-4], {sub StandardIQ}: 2 [2-3], p=<0.0001). The use of a frequency selective non-linear blending algorithm increases the contrast resolution of liver CT and can improve the visibility of the hepatic vasculature in the setting of a low contrast ratio between vessels and the parenchyma.

  11. Impact of P/In flux ratio and epilayer thickness on faceting for nanoscale selective area growth of InP by molecular beam epitaxy.

    Science.gov (United States)

    Fahed, M; Desplanque, L; Coinon, C; Troadec, D; Wallart, X

    2015-07-24

    The impact of the P/In flux ratio and the deposited thickness on the faceting of InP nanostructures selectively grown by molecular beam epitaxy (MBE) is reported. Homoepitaxial growth of InP is performed inside 200 nm wide stripe openings oriented either along a [110] or [1-10] azimuth in a 10 nm thick SiO2 film deposited on an InP(001) substrate. When varying the P/In flux ratio, no major shape differences are observed for [1-10]-oriented apertures. On the other hand, the InP nanostructure cross sections strongly evolve for [110]-oriented apertures for which (111)B facets are more prominent and (001) ones shrink for large P/In flux ratio values. These results show that the growth conditions allow tailoring the nanocrystal shape. They are discussed in the framework of the equilibrium crystal shape model using existing theoretical calculations of the surface energies of different low-index InP surfaces as a function of the phosphorus chemical potential, directly related to the P/In ratio. Experimental observations strongly suggest that the relative (111)A surface energy is probably smaller than the calculated value. We also discuss the evolution of the nanostructure shape with the InP-deposited thickness.

  12. Characteristic of selected frequency luminescence for samples collected in deserts north to Beijing

    International Nuclear Information System (INIS)

    Li Dongxu; Wei Mingjian; Wang Junping; Pan Baolin; Zhao Shiyuan; Liu Zhaowen

    2009-01-01

    Surface sand samples were collected in eight sites of the Horqin and Otindag deserts located in north to Beijing. BG2003 luminescence spectrograph was used to analyze the emitted photons and characteristic spectra of the selected frequency luminescence were obtained. It was found that high intensities of emitted photons stimulated by heat from 85 degree C-135 degree C and 350 degree C-400 degree C. It belong to the traps of 4.13 eV (300 nm), 4.00 eV (310 nm), 3.88 eV (320 nm) and 2.70 eV (460 nm), and the emitted photons belong to traps of 4.00 eV (310 nm), 3.88 eV (320 nm) and 2.70 eV (460 nm) were stimulated by green laser. And sand samples of the eight sites can respond to the increase of definite radiological dose at each wavelength, which is the characteristic spectrum to provide radiation dosimetry basis for dating. There are definite district characteristic in their characteristic spectra. (authors)

  13. The thickness of the A1 pulleys reflects the disability of hand mobility in scleroderma. A pilot study using high-frequency ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Tagliafico, Alberto, E-mail: atagliafico@sirm.org [Department of Radiology, National Institute for Cancer Research, Genova (Italy); Panico, Nicoletta [Division of Immunology, Department of Internal Medicine, University of Genova, Genova (Italy); Serafini, Giovanni [Department of Radiology, Santa Corona Hospital, Pietra Ligure (Italy); Ghio, Massimo [Division of Immunology, Department of Internal Medicine, University of Genova, Genova (Italy); Martinoli, Carlo [Department of Radiology, University of Genova, Genova (Italy)

    2011-02-15

    Background: Hand involvement in scleroderma is a serious concern. Clinical tests to asses hand dysfunction are based on the experience of the clinician. Objective: To asses if utrasonographic (US) measurement of A1 pulley thickness may be used as an indicator of hand mobility in scleroderma. Materials and methods: Institutional review board approval and patient informed consent was obtained. Twenty-eight patients affected suffering from scleroderma and 40 healthy controls were prospectively evaluated by two blinded radiologists with US, with a transducer operating at 17 MHz. A1 pulley thickness was measured and correlated with the Hand Mobility in Scleroderma Test (HAMIS) and disease duration. Results: The thickness of the A1 pulley was greater in sclerodermic patients than in controls (p < 0.05). Intra and inter-observer agreement were better for ultrasound (0.94;0.88) than for HAMIS tests (0.71;0.70). A good correlation between pulley thickness, hand mobility and disease duration was found (r = 0.78, p < 0.018; r = 0.54, p < 0.05). Conclusion: A1 pulley thickness measured on ultrasound correlates with hand mobility and disease duration. Ultrasound is an useful tool to evaluate hand disability in scleroderma.

  14. The thickness of the A1 pulleys reflects the disability of hand mobility in scleroderma. A pilot study using high-frequency ultrasound

    International Nuclear Information System (INIS)

    Tagliafico, Alberto; Panico, Nicoletta; Serafini, Giovanni; Ghio, Massimo; Martinoli, Carlo

    2011-01-01

    Background: Hand involvement in scleroderma is a serious concern. Clinical tests to asses hand dysfunction are based on the experience of the clinician. Objective: To asses if utrasonographic (US) measurement of A1 pulley thickness may be used as an indicator of hand mobility in scleroderma. Materials and methods: Institutional review board approval and patient informed consent was obtained. Twenty-eight patients affected suffering from scleroderma and 40 healthy controls were prospectively evaluated by two blinded radiologists with US, with a transducer operating at 17 MHz. A1 pulley thickness was measured and correlated with the Hand Mobility in Scleroderma Test (HAMIS) and disease duration. Results: The thickness of the A1 pulley was greater in sclerodermic patients than in controls (p < 0.05). Intra and inter-observer agreement were better for ultrasound (0.94;0.88) than for HAMIS tests (0.71;0.70). A good correlation between pulley thickness, hand mobility and disease duration was found (r = 0.78, p < 0.018; r = 0.54, p < 0.05). Conclusion: A1 pulley thickness measured on ultrasound correlates with hand mobility and disease duration. Ultrasound is an useful tool to evaluate hand disability in scleroderma.

  15. Optimized Irregular Low-Density Parity-Check Codes for Multicarrier Modulations over Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Valérian Mannoni

    2004-09-01

    Full Text Available This paper deals with optimized channel coding for OFDM transmissions (COFDM over frequency-selective channels using irregular low-density parity-check (LDPC codes. Firstly, we introduce a new characterization of the LDPC code irregularity called “irregularity profile.” Then, using this parameterization, we derive a new criterion based on the minimization of the transmission bit error probability to design an irregular LDPC code suited to the frequency selectivity of the channel. The optimization of this criterion is done using the Gaussian approximation technique. Simulations illustrate the good performance of our approach for different transmission channels.

  16. Least-squares Migration and Full Waveform Inversion with Multisource Frequency Selection

    KAUST Repository

    Huang, Yunsong

    2013-09-01

    Multisource Least-Squares Migration (LSM) of phase-encoded supergathers has shown great promise in reducing the computational cost of conventional migration. But for the marine acquisition geometry this approach faces the challenge of erroneous misfit due to the mismatch between the limited number of live traces/shot recorded in the field and the pervasive number of traces generated by the finite-difference modeling method. To tackle this mismatch problem, I present a frequency selection strategy with LSM of supergathers. The key idea is, at each LSM iteration, to assign a unique frequency band to each shot gather, so that the spectral overlap among those shots—and therefore their crosstallk—is zero. Consequently, each receiver can unambiguously identify and then discount the superfluous sources—those that are not associated with the receiver in marine acquisition. To compare with standard migration, I apply the proposed method to 2D SEG/EAGE salt model and obtain better resolved images computed at about 1/8 the cost; results for 3D SEG/EAGE salt model, with Ocean Bottom Seismometer (OBS) survey, show a speedup of 40×. This strategy is next extended to multisource Full Waveform Inversion (FWI) of supergathers for marine streamer data, with the same advantages of computational efficiency and storage savings. In the Finite-Difference Time-Domain (FDTD) method, to mitigate spectral leakage due to delayed onsets of sine waves detected at receivers, I double the simulation time and retain only the second half of the simulated records. To compare with standard FWI, I apply the proposed method to 2D velocity model of SEG/EAGE salt and to Gulf Of Mexico (GOM) field data, and obtain a speedup of about 4× and 8×. Formulas are then derived for the resolution limits of various constituent wavepaths pertaining to FWI: diving waves, primary reflections, diffractions, and multiple reflections. They suggest that inverting multiples can provide some low and intermediate

  17. An Approach to Near Field Data Selection in Radio Frequency Identification

    Science.gov (United States)

    Winkworth, Robert D.

    Personal identification is needed in many civil activities, and the common identification cards, such as a driver's license, have become the standard document de facto. Radio frequency identification has complicated this matter. Unlike their printed predecessors, contemporary RFID cards lack a practical way for users to control access to their individual fields of data. This leaves them more available to unauthorized parties, and more prone to abuse. Here, then was undertaken a means to test a novel RFID card technology that allows overlays to be used for reliable, reversible data access settings. Similar to other proposed switching mechanisms, it offers advantages that may greatly improve outcomes. RFID use is increasing in identity documents such as drivers' licenses and passports, and with it concern over the theft of personal information, which can enable unauthorized tracking or fraud. Effort put into designing a strong foundation technology now may allow for widespread development on them later. In this dissertation, such a technology was designed and constructed, to drive the central thesis that selective detuning could serve as a feasible, reliable mechanism. The concept had been illustrated effective in limiting access to all fields simultaneously before, and was here effective in limiting access to specific fields selectively. A novel card was produced in familiar dimensions, with an intuitive interface by which users may conceal the visible print of the card to conceal the wireless emissions it allows. A discussion was included of similar technologies, involving capacitive switching, that could further improve the outcomes if such a product were put to large-scale commercial fabrication. The card prototype was put to a battery of laboratory tests to measure the degree of independence between data fields and the reliability of the switching mechanism when used under realistically variable coverage, demonstrating statistically consistent performance in

  18. Analytical Modeling Approach to Study Harmonic Mitigation in AC Grids with Active Impedance at Selective Frequencies

    Directory of Open Access Journals (Sweden)

    Gonzalo Abad

    2018-05-01

    Full Text Available This paper presents an analytical model, oriented to study harmonic mitigation aspects in AC grids. As it is well known, the presence of non-desired harmonics in AC grids can be palliated in several manners. However, in this paper, a power electronic-based active impedance at selective frequencies (ACISEF is used, due to its already proven flexibility and adaptability to the changing characteristics of AC grids. Hence, the proposed analytical model approach is specially conceived to globally consider both the model of the AC grid itself with its electric equivalent impedances, together with the power electronic-based ACISEF, including its control loops. In addition, the proposed analytical model presents practical and useful properties, as it is simple to understand and simple to use, it has low computational cost and simple adaptability to different scenarios of AC grids, and it provides an accurate enough representation of the reality. The benefits of using the proposed analytical model are shown in this paper through some examples of its usefulness, including an analysis of stability and the identification of sources of instability for a robust design, an analysis of effectiveness in harmonic mitigation, an analysis to assist in the choice of the most suitable active impedance under a given state of the AC grid, an analysis of the interaction between different compensators, and so on. To conclude, experimental validation of a 2.15 kA ACISEF in a real 33 kV AC grid is provided, in which real users (household and industry loads and crucial elements such as wind parks and HVDC systems are near inter-connected.

  19. Contact Selectivity Engineering in a 2 μm Thick Ultrathin c-Si Solar Cell Using Transition-Metal Oxides Achieving an Efficiency of 10.8.

    Science.gov (United States)

    Xue, Muyu; Islam, Raisul; Meng, Andrew C; Lyu, Zheng; Lu, Ching-Ying; Tae, Christian; Braun, Michael R; Zang, Kai; McIntyre, Paul C; Kamins, Theodore I; Saraswat, Krishna C; Harris, James S

    2017-12-06

    In this paper, the integration of metal oxides as carrier-selective contacts for ultrathin crystalline silicon (c-Si) solar cells is demonstrated which results in an ∼13% relative improvement in efficiency. The improvement in efficiency originates from the suppression of the contact recombination current due to the band offset asymmetry of these oxides with Si. First, an ultrathin c-Si solar cell having a total thickness of 2 μm is shown to have >10% efficiency without any light-trapping scheme. This is achieved by the integration of nickel oxide (NiO x ) as a hole-selective contact interlayer material, which has a low valence band offset and high conduction band offset with Si. Second, we show a champion cell efficiency of 10.8% with the additional integration of titanium oxide (TiO x ), a well-known material for an electron-selective contact interlayer. Key parameters including V oc and J sc also show different degrees of enhancement if single (NiO x only) or double (both NiO x and TiO x ) carrier-selective contacts are integrated. The fabrication process for TiO x and NiO x layer integration is scalable and shows good compatibility with the device.

  20. Analysis of the rebalancing frequency in log-optimal portfolio selection

    OpenAIRE

    Kuhn, Daniel; Luenberger, David G.

    2010-01-01

    In a dynamic investment situation, the right timing of portfolio revisions and adjustments is essential to sustain long-term growth. A high rebalancing frequency reduces the portfolio performance in the presence of transaction costs, whereas a low rebalancing frequency entails a static investment strategy that hardly reacts to changing market conditions. This article studies a family of portfolio problems in a Black-Scholes type economy which depend parametrically on the rebalancing frequency...

  1. Performance Analysis of OFDM in Frequency Selective, Slowly Fading Nakagami Channels

    National Research Council Canada - National Science Library

    Count, Patrick

    2001-01-01

    In an effort to offer faster, more reliable wireless communications services to the public, many wireless standardization committees have, in recent years, adopted Orthogonal Frequency Division Multiplexing (OFDM...

  2. Channel and delay estimation for base-station–based cooperative communications in frequency-selective fading channels

    Directory of Open Access Journals (Sweden)

    Hongjun Xu

    2011-07-01

    Full Text Available A channel and delay estimation algorithm for both positive and negative delay, based on the distributed Alamouti scheme, has been recently discussed for base-station–based asynchronous cooperative systems in frequency-flat fading channels. This paper extends the algorithm, the maximum likelihood estimator, to work in frequency-selective fading channels. The minimum mean square error (MMSE performance of channel estimation for both packet schemes and normal schemes is discussed in this paper. The symbol error rate (SER performance of equalisation and detection for both time-reversal space-time block code (STBC and single-carrier STBC is also discussed in this paper. The MMSE simulation results demonstrated the superior performance of the packet scheme over the normal scheme with an improvement in performance of up to 6 dB when feedback was used in the frequency-selective channel at a MSE of 3 x 10–2. The SER simulation results showed that, although both the normal and packet schemes achieved similar diversity orders, the packet scheme demonstrated a 1 dB coding gain over the normal scheme at a SER of 10–5. Finally, the SER simulations showed that the frequency-selective fading system outperformed the frequency-flat fading system.

  3. Mixed Stimulus-Induced Mode Selection in Neural Activity Driven by High and Low Frequency Current under Electromagnetic Radiation

    Directory of Open Access Journals (Sweden)

    Lulu Lu

    2017-01-01

    Full Text Available The electrical activities of neurons are dependent on the complex electrophysiological condition in neuronal system, the three-variable Hindmarsh-Rose (HR neuron model is improved to describe the dynamical behaviors of neuronal activities with electromagnetic induction being considered, and the mode transition of electrical activities in neuron is detected when external electromagnetic radiation is imposed on the neuron. In this paper, different types of electrical stimulus impended with a high-low frequency current are imposed on new HR neuron model, and mixed stimulus-induced mode selection in neural activity is discussed in detail. It is found that mode selection of electrical activities stimulated by high-low frequency current, which also changes the excitability of neuron, can be triggered owing to adding the Gaussian white noise. Meanwhile, the mode selection of the neuron electrical activity is much dependent on the amplitude B of the high frequency current under the same noise intensity, and the high frequency response is selected preferentially by applying appropriate parameters and noise intensity. Our results provide insights into the transmission of complex signals in nerve system, which is valuable in engineering prospective applications such as information encoding.

  4. Phased arrays of compact waveguide radiators and frequency selective surfaces : a multi-mode equivalent network approach

    NARCIS (Netherlands)

    Gerini, G.

    2003-01-01

    The current trend for radar array antennas requires increased integration, as well as large bandwidth, for multifunction systems, and frequency/angular selectivity properties for structural integration on military platforms, like ships and aircrafts, with low radar cross section (RCS). We have

  5. Is the colour dimorphism in Dactylorhiza sambucina maintained by differential seed viability instead of frequency-dependent selection?

    Czech Academy of Sciences Publication Activity Database

    Jersáková, Jana; Kindlmann, Pavel; Renner, S.S.

    2006-01-01

    Roč. 41, - (2006), s. 61-76 ISSN 0015-5551 R&D Projects: GA AV ČR(CZ) KJB6141302 Keywords : Dactylorhiza * flower colour polymorphism * frequency-dependent selection * pollinator discrimination * rewardless flowers * seed viability Subject RIV: EF - Botanics Impact factor: 1.033, year: 2005

  6. Selective Attention and Distractor Frequency in Naming Performance: Comment on Dhooge and Hartsuiker (2010)

    Science.gov (United States)

    Roelofs, Ardi; Piai, Vitoria; Schriefers, Herbert

    2011-01-01

    E. Dhooge and R. J. Hartsuiker (2010) reported experiments showing that picture naming takes longer with low- than high-frequency distractor words, replicating M. Miozzo and A. Caramazza (2003). In addition, they showed that this distractor-frequency effect disappears when distractors are masked or preexposed. These findings were taken to refute…

  7. Thick Toenails

    Science.gov (United States)

    ... in individuals with nail fungus (onychomycosis), psoriasis and hypothyroidism. Those who have problems with the thickness of their toenails should consult a foot and ankle surgeon for proper diagnosis and treatment. Find an ACFAS Physician Search Search Tools Find ...

  8. Collection, processing, and interpretation of ground-penetrating radar data to determine sediment thickness at selected locations in Deep Creek Lake, Garrett County, Maryland, 2007

    Science.gov (United States)

    Banks, William S.L.; Johnson, Carole D.

    2011-01-01

    The U.S. Geological Survey collected geophysical data in Deep Creek Lake in Garrett County, Maryland, between September 17 through October 4, 2007 to assist the Maryland Department of Natural Resources to better manage resources of the Lake. The objectives of the geophysical surveys were to provide estimates of sediment thickness in shallow areas around the Lake and to test the usefulness of three geophysical methods in this setting. Ground-penetrating radar (GPR), continuous seismic-reflection profiling (CSP), and continuous resistivity profiling (CRP) were attempted. Nearly 90 miles of GPR radar data and over 70 miles of CSP data were collected throughout the study area. During field deployment and testing, CRP was determined not to be practical and was not used on a large scale. Sediment accumulation generally could be observed in the radar profiles in the shallow coves. In some seismic profiles, a thin layer of sediment could be observed at the water bottom. The radar profiles appeared to be better than the seismic profiles for the determination of sediment thickness. Although only selected data profiles were processed, all data were archived for future interpretation.

  9. Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags : the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique

    NARCIS (Netherlands)

    Sanchez-Romaquera, V.; Wïnscher, S.; Turki, B.M.; Abbel, R.J.; Barbosa, S.; Tate, D.J.; Oyeka, D.; Batchelor, J.C.; Parker, E.A.; Schubert, U.S.; Yeates, S.G.

    2015-01-01

    Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices

  10. Selecting the optimum engineering model for the frequency response of fcc nanowire resonators

    DEFF Research Database (Denmark)

    Nasr Esfahani, M.; Yilmaz, M.; Sonne, Mads Rostgaard

    2017-01-01

    of extreme surface-to-volume ratios remains question- able. Classical finite element method can partially be used to address these deficiencies. On the other hand, molecular dynamics provide accurate results, while nanowire geome- tries studied with this computationally demanding technique usually remain...... confined to dimensions below those of practical interest. To address these issues, a benchmarking study among analytical and numerical techniques is carried out, where Surface Cauchy–Born theory serves as the reference. Using gold nanowires with different dimensions and boundary conditions, it is observed......-to-thickness ratios exceeding 11 for both the analytical approach and the classical finite element method in the fixed–fixed structure. The deviations are quantitatively linked to the dominance of the surface effect through the use of the Surface Cauchy–Born model. For length-to-thickness ratios less than 7, the lack...

  11. Practically Efficient Blind Speech Separation Using Frequency Band Selection Based on Magnitude Squared Coherence and a Small Dodecahedral Microphone Array

    Directory of Open Access Journals (Sweden)

    Kazunobu Kondo

    2012-01-01

    Full Text Available Small agglomerative microphone array systems have been proposed for use with speech communication and recognition systems. Blind source separation methods based on frequency domain independent component analysis have shown significant separation performance, and the microphone arrays are small enough to make them portable. However, the level of computational complexity involved is very high because the conventional signal collection and processing method uses 60 microphones. In this paper, we propose a band selection method based on magnitude squared coherence. Frequency bands are selected based on the spatial and geometric characteristics of the microphone array device which is strongly related to the dodecahedral shape, and the selected bands are nonuniformly spaced. The estimated reduction in the computational complexity is 90% with a 68% reduction in the number of frequency bands. Separation performance achieved during our experimental evaluation was 7.45 (dB (signal-to-noise ratio and 2.30 (dB (cepstral distortion. These results show improvement in performance compared to the use of uniformly spaced frequency band.

  12. Relevance feature selection of modal frequency-ambient condition pattern recognition in structural health assessment for reinforced concrete buildings

    Directory of Open Access Journals (Sweden)

    He-Qing Mu

    2016-08-01

    Full Text Available Modal frequency is an important indicator for structural health assessment. Previous studies have shown that this indicator is substantially affected by the fluctuation of ambient conditions, such as temperature and humidity. Therefore, recognizing the pattern between modal frequency and ambient conditions is necessary for reliable long-term structural health assessment. In this article, a novel machine-learning algorithm is proposed to automatically select relevance features in modal frequency-ambient condition pattern recognition based on structural dynamic response and ambient condition measurement. In contrast to the traditional feature selection approaches by examining a large number of combinations of extracted features, the proposed algorithm conducts continuous relevance feature selection by introducing a sophisticated hyperparameterization on the weight parameter vector controlling the relevancy of different features in the prediction model. The proposed algorithm is then utilized for structural health assessment for a reinforced concrete building based on 1-year daily measurements. It turns out that the optimal model class including the relevance features for each vibrational mode is capable to capture the pattern between the corresponding modal frequency and the ambient conditions.

  13. Autonomous generator based on Ni-Mn-Ga microactuator as a frequency selective element

    Directory of Open Access Journals (Sweden)

    Barandiaran J.M.

    2013-01-01

    Full Text Available In this work, we suggest the temperature-induced resistivity change at the martensitic transformation in the Ni-Mn-Ga ferromagnetic shape memory alloy as a driving mechanism enabling periodic signal generation. We demonstrated its practical importance by a design of the prototype of a low-frequency autonomous generator. A prominent feature of this new generator is a control of its frequency by the external magnetic field.

  14. Spatial organization of frequency preference and selectivity in the human inferior colliculus

    OpenAIRE

    De Martino, Federico; Moerel, Michelle; van de Moortele, Pierre-Francois; Ugurbil, Kamil; Goebel, Rainer; Yacoub, Essa; Formisano, Elia

    2013-01-01

    To date, the functional organization of human auditory sub-cortical structures can only be inferred from animal models. Here we use high-resolution functional MRI at ultra-high magnetic fields (7 Tesla) to map the organization of spectral responses in the human inferior colliculus (hIC), a sub-cortical structure fundamental for sound processing. We reveal a tonotopic map with a spatial gradient of preferred frequencies approximately oriented from dorso-lateral (low frequencies) to ventro-medi...

  15. Modeling coverage gaps in haplotype frequencies via Bayesian inference to improve stem cell donor selection.

    Science.gov (United States)

    Louzoun, Yoram; Alter, Idan; Gragert, Loren; Albrecht, Mark; Maiers, Martin

    2018-05-01

    Regardless of sampling depth, accurate genotype imputation is limited in regions of high polymorphism which often have a heavy-tailed haplotype frequency distribution. Many rare haplotypes are thus unobserved. Statistical methods to improve imputation by extending reference haplotype distributions using linkage disequilibrium patterns that relate allele and haplotype frequencies have not yet been explored. In the field of unrelated stem cell transplantation, imputation of highly polymorphic human leukocyte antigen (HLA) genes has an important application in identifying the best-matched stem cell donor when searching large registries totaling over 28,000,000 donors worldwide. Despite these large registry sizes, a significant proportion of searched patients present novel HLA haplotypes. Supporting this observation, HLA population genetic models have indicated that many extant HLA haplotypes remain unobserved. The absent haplotypes are a significant cause of error in haplotype matching. We have applied a Bayesian inference methodology for extending haplotype frequency distributions, using a model where new haplotypes are created by recombination of observed alleles. Applications of this joint probability model offer significant improvement in frequency distribution estimates over the best existing alternative methods, as we illustrate using five-locus HLA frequency data from the National Marrow Donor Program registry. Transplant matching algorithms and disease association studies involving phasing and imputation of rare variants may benefit from this statistical inference framework.

  16. Suzaku  Observations of Heavily Obscured (Compton-thick) Active Galactic Nuclei Selected by the Swift/BAT Hard X-Ray Survey

    Science.gov (United States)

    Tanimoto, Atsushi; Ueda, Yoshihiro; Kawamuro, Taiki; Ricci, Claudio; Awaki, Hisamitsu; Terashima, Yuichi

    2018-02-01

    We present a uniform broadband X-ray (0.5–100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick ({log}{N}{{H}}/{{cm}}-2≥slant 24) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku data of three objects are published here for the first time. We fit the Suzaku and Swift spectra with models utilizing an analytic reflection code and those utilizing the Monte-Carlo-based model from an AGN torus by Ikeda et al. The main results are as follows: (1) The estimated intrinsic luminosity of a CTAGN strongly depends on the model; applying Compton scattering to the transmitted component in an analytic model may largely overestimate the intrinsic luminosity at large column densities. (2) Unabsorbed reflection components are commonly observed, suggesting that the tori are clumpy. (3) Most of CTAGNs show small scattering fractions (<0.5%), implying a buried AGN nature. (4) Comparison with the results obtained for Compton-thin AGNs suggests that the properties of these CTAGNs can be understood as a smooth extension from Compton-thin AGNs with heavier obscuration; we find no evidence that the bulk of the population of hard-X-ray-selected CTAGNs are different from less obscured objects.

  17. High frequency action potential bursts (≥ 100 Hz) in L2/3 and L5B thick tufted neurons in anaesthetized and awake rat primary somatosensory cortex

    NARCIS (Netherlands)

    C.P.J. de Kock (Christiaan); B. Sakmann (Bert)

    2008-01-01

    textabstractHigh frequency (≥ 100 Hz) bursts of action potentials (APs) generated by neocortical neurons are thought to increase information content and, through back-propagation, to influence synaptic integration and efficacy in distal dendritic compartments. It was recently shown in acute slice

  18. Saccade frequency response to visual cues during gait in Parkinson's disease: the selective role of attention.

    Science.gov (United States)

    Stuart, Samuel; Lord, Sue; Galna, Brook; Rochester, Lynn

    2018-04-01

    Gait impairment is a core feature of Parkinson's disease (PD) with implications for falls risk. Visual cues improve gait in PD, but the underlying mechanisms are unclear. Evidence suggests that attention and vision play an important role; however, the relative contribution from each is unclear. Measurement of visual exploration (specifically saccade frequency) during gait allows for real-time measurement of attention and vision. Understanding how visual cues influence visual exploration may allow inferences of the underlying mechanisms to response which could help to develop effective therapeutics. This study aimed to examine saccade frequency during gait in response to a visual cue in PD and older adults and investigate the roles of attention and vision in visual cue response in PD. A mobile eye-tracker measured saccade frequency during gait in 55 people with PD and 32 age-matched controls. Participants walked in a straight line with and without a visual cue (50 cm transverse lines) presented under single task and dual-task (concurrent digit span recall). Saccade frequency was reduced when walking in PD compared to controls; however, visual cues ameliorated saccadic deficit. Visual cues significantly increased saccade frequency in both PD and controls under both single task and dual-task. Attention rather than visual function was central to saccade frequency and gait response to visual cues in PD. In conclusion, this study highlights the impact of visual cues on visual exploration when walking and the important role of attention in PD. Understanding these complex features will help inform intervention development. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  19. The relationship between brightness temperature and soil moisture. Selection of frequency range for microwave remote sensing

    International Nuclear Information System (INIS)

    Rao, K.S.; Chandra, G.; Rao, P.V.N.

    1987-01-01

    The analysis of brightness temperature data acquired from field and aircraft experiments demonstrates a linear relationship between soil moisture and brightness temperature. However, the analysis of brightness temperature data acquired by the Skylab radiometer demonstrates a non-linear relationship between soil moisture and brightness temperature. In view of the above and also because of recent theoretical developments for the calculation of the dielectric constant and brightness temperature under varying soil moisture profile conditions, an attempt is made to study the theoretical relationship between brightness temperature and soil moisture as a function of frequency. Through the above analysis, the appropriate microwave frequency range for soil moisture studies is recommended

  20. Selection of the wavelet function for the frequencies estimation; Seleccion de la funcion wavelet para la estimacion de frecuencias

    Energy Technology Data Exchange (ETDEWEB)

    Garcia R, A. [ININ, Carretera Mexico-Toluca S/N, 52750 La Marquesa, Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: ramador@nuclear.inin.mx

    2007-07-01

    At the moment the signals are used to diagnose the state of the systems, by means of the extraction of their more important characteristics such as the frequencies, tendencies, changes and temporary evolutions. This characteristics are detected by means of diverse analysis techniques, as Autoregressive methods, Fourier Transformation, Fourier transformation in short time, Wavelet transformation, among others. The present work uses the one Wavelet transformation because it allows to analyze stationary, quasi-stationary and transitory signals in the time-frequency plane. It also describes a methodology to select the scales and the Wavelet function to be applied the one Wavelet transformation with the objective of detecting to the dominant system frequencies. (Author)

  1. Selecting informative food items for compiling food-frequency questionnaires: Comparison of procedures

    NARCIS (Netherlands)

    Molag, M.L.; Vries, J.H.M. de; Duif, N.; Ocké, M.C.; Dagnelie, P.C.; Goldbohm, R.A.; Veer, P. van 't

    2010-01-01

    The authors automated the selection of foods in a computer system that compiles and processes tailored FFQ. For the selection of food items, several methods are available. The aim of the present study was to compare food lists made by MOM2, which identifies food items with highest between-person

  2. Optimising the selection of food items for food frequency questionnaires using Mixed Integer Linear Programming

    NARCIS (Netherlands)

    Lemmen-Gerdessen, van J.C.; Souverein, O.W.; Veer, van 't P.; Vries, de J.H.M.

    2015-01-01

    Objective To support the selection of food items for FFQs in such a way that the amount of information on all relevant nutrients is maximised while the food list is as short as possible. Design Selection of the most informative food items to be included in FFQs was modelled as a Mixed Integer Linear

  3. Fringe order correction for the absolute phase recovered by two selected spatial frequency fringe projections in fringe projection profilometry.

    Science.gov (United States)

    Ding, Yi; Peng, Kai; Yu, Miao; Lu, Lei; Zhao, Kun

    2017-08-01

    The performance of the two selected spatial frequency phase unwrapping methods is limited by a phase error bound beyond which errors will occur in the fringe order leading to a significant error in the recovered absolute phase map. In this paper, we propose a method to detect and correct the wrong fringe orders. Two constraints are introduced during the fringe order determination of two selected spatial frequency phase unwrapping methods. A strategy to detect and correct the wrong fringe orders is also described. Compared with the existing methods, we do not need to estimate the threshold associated with absolute phase values to determine the fringe order error, thus making it more reliable and avoiding the procedure of search in detecting and correcting successive fringe order errors. The effectiveness of the proposed method is validated by the experimental results.

  4. Low-frequency fluctuation regime in a multimode semiconductor laser subject to a mode-selective optical feedback

    International Nuclear Information System (INIS)

    Rogister, F.; Sciamanna, M.; Deparis, O.; Megret, P.; Blondel, M.

    2002-01-01

    We study numerically the dynamics of a multimode laser diode subject to a mode-selective optical feedback by using a generalization of the Lang-Kobayashi equations. In this configuration, only one longitudinal mode of the laser is reinjected into the laser cavity; the other modes are free. When the laser operates in the low-frequency fluctuation regime, our model predicts intensity bursts in the free modes simultaneously with dropouts in the selected mode, in good agreement with recent experiments. In the frame of our model, intensity bursts and dropouts are associated with collisions of the system trajectory in phase space with saddle-type antimodes

  5. Trade-offs between microbial growth phases lead to frequency-dependent and non-transitive selection.

    Science.gov (United States)

    Manhart, Michael; Adkar, Bharat V; Shakhnovich, Eugene I

    2018-02-14

    Mutations in a microbial population can increase the frequency of a genotype not only by increasing its exponential growth rate, but also by decreasing its lag time or adjusting the yield (resource efficiency). The contribution of multiple life-history traits to selection is a critical question for evolutionary biology as we seek to predict the evolutionary fates of mutations. Here we use a model of microbial growth to show that there are two distinct components of selection corresponding to the growth and lag phases, while the yield modulates their relative importance. The model predicts rich population dynamics when there are trade-offs between phases: multiple strains can coexist or exhibit bistability due to frequency-dependent selection, and strains can engage in rock-paper-scissors interactions due to non-transitive selection. We characterize the environmental conditions and patterns of traits necessary to realize these phenomena, which we show to be readily accessible to experiments. Our results provide a theoretical framework for analysing high-throughput measurements of microbial growth traits, especially interpreting the pleiotropy and correlations between traits across mutants. This work also highlights the need for more comprehensive measurements of selection in simple microbial systems, where the concept of an ordinary fitness landscape breaks down. © 2018 The Author(s).

  6. Similar patterns of frequency-dependent selection on animal personalities emerge in three species of social spiders.

    Science.gov (United States)

    Lichtenstein, J L L; Pruitt, J N

    2015-06-01

    Frequency-dependent selection is thought to be a major contributor to the maintenance of phenotypic variation. We tested for frequency-dependent selection on contrasting behavioural strategies, termed here 'personalities', in three species of social spiders, each thought to represent an independent evolutionary origin of sociality. The evolution of sociality in the spider genus Anelosimus is consistently met with the emergence of two temporally stable discrete personality types: an 'aggressive' or 'docile' form. We assessed how the foraging success of each phenotype changes as a function of its representation within a colony. We did this by creating experimental colonies of various compositions (six aggressives, three aggressives and three dociles, one aggressive and five dociles, six dociles), maintaining them in a common garden for 3 weeks, and tracking the mass gained by individuals of either phenotype. We found that both the docile and aggressive phenotypes experienced their greatest mass gain in mixed colonies of mostly docile individuals. However, the performance of both phenotypes decreased as the frequency of the aggressive phenotype increased. Nearly identical patterns of phenotype-specific frequency dependence were recovered in all three species. Naturally occurring colonies of these spiders exhibit mixtures dominated by the docile phenotype, suggesting that these spiders may have evolved mechanisms to maintain the compositions that maximize the success of the colony without compromising the expected reproductive output of either phenotype. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  7. A study of frequency effects on conductivity measurements

    International Nuclear Information System (INIS)

    Nurul Ain Ahmad Latif; Mahmood Dollah; Mohd Khidir Kamaron; Suaib Ibrahim

    2010-01-01

    In eddy current testing (ET), different measurement can be carry out through the selection of the test frequency. In conductivity measurement, the selection of eddy current test frequencies permits to select the specific material properties to be measured. The test frequency selected should be sufficient high that eddy current penetration is limited only to fraction of the test material thickness. This paper describes the effects of test frequency on the conductivity measurement. This experiment done by applying different values of test frequency which is 20 kHz, 100 kHz and 1 MHz. (author)

  8. Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures

    OpenAIRE

    Chouteau, Mathieu; Llaurens, Violaine; Piron-Prunier, Florence; Joron, Mathieu

    2017-01-01

    Although biological diversity is being lost at an alarming rate, a mimetic butterfly from the Amazon reveals a selective mechanism that can lead to rich adaptive diversity. In these toxic and vividly colored butterflies, several forms are maintained within populations, accurately mimicking distinct local butterflies, and controlled by differentiated alleles of a supergene. Such diversity is not expected because selection by predators promotes the fixation of a single morph. We show that the m...

  9. Predicting the effect of relaxation during frequency-selective adiabatic pulses

    Science.gov (United States)

    Pfaff, Annalise R.; McKee, Cailyn E.; Woelk, Klaus

    2017-11-01

    Adiabatic half and full passages are invaluable for achieving uniform, B1-insensitive excitation or inversion of macroscopic magnetization across a well-defined range of NMR frequencies. To accomplish narrow frequency ranges with adiabatic pulses (computer-calculated data with experimental results demonstrates that, in non-viscous, small-molecule fluids, it is possible to model magnetization and relaxation by considering standard T1 and T2 relaxation in the traditional rotating frame. The proposed model is aimed at performance optimizations of applications in which these pulses are employed. It differs from previous reports which focused on short high-power adiabatic pulses and relaxation that is governed by dipole-dipole interactions, cross polarization, or chemical exchange.

  10. Price duration versus trading volume in high-frequency data for selected DAX companies

    Directory of Open Access Journals (Sweden)

    Christoph Mitterer

    2016-12-01

    Full Text Available The properties of the time series of durations between consecutive trades of a particular stock have been studied by many contributors in the literature of financial econometrics. Among them are highly prominent scientists like Engle (2000 and Gourieroux and Jasiak (2001. The importance of this topic, accompanied by the growing availability of (ultra-high-frequency data, has prompted an increase of contributions in recent years. Intensive research based on high-frequency data has several financial motivations. First of all, it is linked with microstructure theory. Secondly, it contributes to the literature on stochastic time deformation. But the most important need for research on the dynamics of trade durations is the necessity to manage liquidity risk. The reason is that durations between the following trades are a widely accepted measures of market liquidity. In addition, their volatility reflects the liquidity risk.

  11. Online Optimal Switching Frequency Selection for Grid-Connected Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Saher Albatran

    2017-12-01

    Full Text Available Enhancing the performance of the voltage source inverters (VSIs without changing the hardware structure has recently acquired an increased amount of interest. In this study, an optimization algorithm, enhancing the quality of the output power and the efficiency of three-phase grid connected VSIs is proposed. Towards that end, the proposed algorithm varies the switching frequency (fsw to maintain the best balance between switching losses of the insulated-gate-bipolar-transistor (IGBT power module as well as the output power quality under all loading conditions, including the ambient temperature effect. Since there is a contradiction with these two measures in relation to the switching frequency, the theory of multi-objective optimization is employed. The proposed algorithm is executed on the platform of Altera® DE2-115 field-programmable-gate-array (FPGA in which the optimal value of the switching frequency is determined online without the need for heavy offline calculations and/or lookup tables. With adopting the proposed algorithm, there is an improvement in the VSI efficiency without degrading the output power quality. Therefore, the proposed algorithm enhances the lifetime of the IGBT power module because of reduced variations in the module’s junction temperature. An experimental prototype is built, and experimental tests are conducted for the verification of the viability of the proposed algorithm.

  12. Binary particle swarm optimization for frequency band selection in motor imagery based brain-computer interfaces.

    Science.gov (United States)

    Wei, Qingguo; Wei, Zhonghai

    2015-01-01

    A brain-computer interface (BCI) enables people suffering from affective neurological diseases to communicate with the external world. Common spatial pattern (CSP) is an effective algorithm for feature extraction in motor imagery based BCI systems. However, many studies have proved that the performance of CSP depends heavily on the frequency band of EEG signals used for the construction of covariance matrices. The use of different frequency bands to extract signal features may lead to different classification performances, which are determined by the discriminative and complementary information they contain. In this study, the broad frequency band (8-30 Hz) is divided into 10 sub-bands of band width 4 Hz and overlapping 2 Hz. Binary particle swarm optimization (BPSO) is used to find the best sub-band set to improve the performance of CSP and subsequent classification. Experimental results demonstrate that the proposed method achieved an average improvement of 6.91% in cross-validation accuracy when compared to broad band CSP.

  13. Selective detection of crystalline cellulose in plant cell walls with sum-frequency-generation (SFG) vibration spectroscopy.

    Science.gov (United States)

    Barnette, Anna L; Bradley, Laura C; Veres, Brandon D; Schreiner, Edward P; Park, Yong Bum; Park, Junyeong; Park, Sunkyu; Kim, Seong H

    2011-07-11

    The selective detection of crystalline cellulose in biomass was demonstrated with sum-frequency-generation (SFG) vibration spectroscopy. SFG is a second-order nonlinear optical response from a system where the optical centrosymmetry is broken. In secondary plant cell walls that contain mostly cellulose, hemicellulose, and lignin with varying concentrations, only certain vibration modes in the crystalline cellulose structure can meet the noninversion symmetry requirements. Thus, SFG can be used to detect and analyze crystalline cellulose selectively in lignocellulosic biomass without extraction of noncellulosic species from biomass or deconvolution of amorphous spectra. The selective detection of crystalline cellulose in lignocellulosic biomass is not readily achievable with other techniques such as XRD, solid-state NMR, IR, and Raman analyses. Therefore, the SFG analysis presents a unique opportunity to reveal the cellulose crystalline structure in lignocellulosic biomass.

  14. Individual common carotid artery wall layer dimensions, but not carotid intima-media thickness, indicate increased cardiovascular risk in women with preeclampsia: an investigation using noninvasive high-frequency ultrasound.

    Science.gov (United States)

    Akhter, Tansim; Wikström, Anna-Karin; Larsson, Marita; Naessen, Tord

    2013-09-01

    Preeclampsia (PE) is associated with increased risk of cardiovascular disease later in life. Ultrasound assessment of the common carotid artery intima-media thickness (IMT) during or after PE has not indicated any increased cardiovascular risk. We used high-frequency ultrasound (22 MHz) to estimate the individual common carotid artery IMTs in 55 women at PE diagnosis and in 64 women with normal pregnancies at a similar stage. All were re-examined about 1 year postpartum. A thick intima, thin media, and high intima/media (I/M) ratio are signs of a less healthy artery wall. PE was associated with a significantly thicker mean common carotid artery intima, thinner media, and higher I/M ratio than in normal pregnancy (mean I/M difference, 0.21; 95% confidence interval, 0.17-0.25; Pwomen with PE were negatively affected during pregnancy and 1 year postpartum compared with women with normal pregnancies, indicating increased cardiovascular risk. Estimation of intima thickness and I/M ratio seem preferable to estimation of common carotid artery IMT in imaging cardiovascular risk in PE. Results from this pilot study warrant further confirmation.

  15. A hybrid polarization-selective atomic sensor for radio-frequency field detection with a passive resonant-cavity field amplifier

    OpenAIRE

    Anderson, David A.; Paradis, Eric G.; Raithel, Georg

    2018-01-01

    We present a hybrid atomic sensor that realizes radio-frequency electric field detection with intrinsic field amplification and polarization selectivity for robust high-sensitivity field measurement. The hybrid sensor incorporates a passive resonator element integrated with an atomic vapor cell that provides amplification and polarization selectivity for detection of incident radio-frequency fields. The amplified intra-cavity radio-frequency field is measured by atoms using a quantum-optical ...

  16. Semantic Wavelet-Induced Frequency-Tagging (SWIFT Periodically Activates Category Selective Areas While Steadily Activating Early Visual Areas.

    Directory of Open Access Journals (Sweden)

    Roger Koenig-Robert

    Full Text Available Primate visual systems process natural images in a hierarchical manner: at the early stage, neurons are tuned to local image features, while neurons in high-level areas are tuned to abstract object categories. Standard models of visual processing assume that the transition of tuning from image features to object categories emerges gradually along the visual hierarchy. Direct tests of such models remain difficult due to confounding alteration in low-level image properties when contrasting distinct object categories. When such contrast is performed in a classic functional localizer method, the desired activation in high-level visual areas is typically accompanied with activation in early visual areas. Here we used a novel image-modulation method called SWIFT (semantic wavelet-induced frequency-tagging, a variant of frequency-tagging techniques. Natural images modulated by SWIFT reveal object semantics periodically while keeping low-level properties constant. Using functional magnetic resonance imaging (fMRI, we indeed found that faces and scenes modulated with SWIFT periodically activated the prototypical category-selective areas while they elicited sustained and constant responses in early visual areas. SWIFT and the localizer were selective and specific to a similar extent in activating category-selective areas. Only SWIFT progressively activated the visual pathway from low- to high-level areas, consistent with predictions from standard hierarchical models. We confirmed these results with criterion-free methods, generalizing the validity of our approach and show that it is possible to dissociate neural activation in early and category-selective areas. Our results provide direct evidence for the hierarchical nature of the representation of visual objects along the visual stream and open up future applications of frequency-tagging methods in fMRI.

  17. Selectivity enhancement in photoacoustic gas analysis via phase-sensitive detection at high modulation frequency

    Science.gov (United States)

    Kosterev, Anatoliy (Inventor)

    2010-01-01

    A method for detecting a target fluid in a fluid sample comprising a first fluid and the target fluid using photoacoustic spectroscopy (PAS), comprises a) providing a light source configured to introduce an optical signal having at least one wavelength into the fluid sample; b) modulating the optical signal at a desired modulation frequency such that the optical signal generates an acoustic signal in the fluid sample; c) measuring the acoustic signal in a resonant acoustic detector; and d) using the phase of the acoustic signal to detect the presence of the target fluid.

  18. Frequency-dependent selection on female morphs driven by premating interactions with males

    NARCIS (Netherlands)

    Bots, Jessica; Iserbyt, Arne; Van Gossum, Hans; Hammers, Martijn; Sherratt, Thomas N.

    Species showing color polymorphisms-the presence of two or more genetically determined color morphs within a single population-are excellent systems for studying the selective forces driving the maintenance of genetic diversity. Despite a shortage of empirical evidence, it is often suggested that

  19. Selection of mother wavelets for the detection of the oscillation frequencies in power signals of nuclear reactors

    International Nuclear Information System (INIS)

    Amador G, R.; Castillo D, R.; Ortiz V, J.

    2007-01-01

    Diverse types of transitory events can lead to oscillations of power in nuclear reactors. In such events, the power monitors provide a signal that contains important characteristics of the transitory one, as the oscillation frequency, tendencies, changes and the instants or periods in those that important events are presented. This characteristics are detected by means of diverse analysis techniques, as Autoregressive methods, Fourier Transform, Fourier Transform in Short Time, Wavelets Transform, among others. Presently work is used the one Wavelets Continuous Transform because it allows to carry out studies of the stationary, quasi-stationary and transitory signals in the Time-scale and Time-scale-spectrum planes. Contrary to other similar works, this work describes a methodology for the selection of the scales and the Wavelet mother to be applied the one Wavelets Continuous Transform, with the objective of detecting to the dominant frequencies of the system. To prove the proposal a broadly well-known real signal of an event of power oscillations it has been used. The obtained results correspond to three families of Wavelets mothers that fulfilled the conditions of scales and central frequency of the proposal. The results show that the value of the certain frequency oscillation in this work is practically the same one reported in other studies with other techniques. (Author)

  20. Feasibility Studies on the Use of Higher Frequency Bands and Beamforming Selection Scheme for High Speed Train Communication

    Directory of Open Access Journals (Sweden)

    Ayotunde O. Laiyemo

    2017-01-01

    Full Text Available With increasing popularity of high speed trains and traffic forecast for future cellular networks, the need to provide improved data rates using higher frequency bands (HFBs for train passengers is becoming crucial. In this paper, we modify the OFDM frame structure for HST, taking into account the increasing sensitivity to speed at HFBs. A lower bound on the SNR/SINR for a given rate for reliable communication was derived considering the physical layer parameters from the OFDM frame. We also analyze different pathloss models in the context of examining the required gain needed to achieve the same performance as with microwave bands. Finally, we present a time-based analogue beamforming selection approach for HST. We observed that, irrespective of the pathloss models used, the required gains are within the same range. For the same SNR/SINR at different frequency bands, the achievable data rate varies with respect to the frequency bands. Our results show the potential of the use of HFBs. However, due to the increased sensitivity of some channel parameters, a maximum frequency band of 38 GHz is suggested. Evaluation of our proposed beamforming scheme indicates a close performance to the optimal SVD scheme with a marginal rate gap of less than 2 b/s/Hz.

  1. Application of site and haplotype-frequency based approaches for detecting selection signatures in cattle

    Directory of Open Access Journals (Sweden)

    Moore Stephen

    2011-06-01

    Full Text Available Abstract Background 'Selection signatures' delimit regions of the genome that are, or have been, functionally important and have therefore been under either natural or artificial selection. In this study, two different and complementary methods--integrated Haplotype Homozygosity Score (|iHS| and population differentiation index (FST--were applied to identify traces of decades of intensive artificial selection for traits of economic importance in modern cattle. Results We scanned the genome of a diverse set of dairy and beef breeds from Germany, Canada and Australia genotyped with a 50 K SNP panel. Across breeds, a total of 109 extreme |iHS| values exceeded the empirical threshold level of 5% with 19, 27, 9, 10 and 17 outliers in Holstein, Brown Swiss, Australian Angus, Hereford and Simmental, respectively. Annotating the regions harboring clustered |iHS| signals revealed a panel of interesting candidate genes like SPATA17, MGAT1, PGRMC2 and ACTC1, COL23A1, MATN2, respectively, in the context of reproduction and muscle formation. In a further step, a new Bayesian FST-based approach was applied with a set of geographically separated populations including Holstein, Brown Swiss, Simmental, North American Angus and Piedmontese for detecting differentiated loci. In total, 127 regions exceeding the 2.5 per cent threshold of the empirical posterior distribution were identified as extremely differentiated. In a substantial number (56 out of 127 cases the extreme FST values were found to be positioned in poor gene content regions which deviated significantly (p ST values were found in regions of some relevant genes such as SMCP and FGF1. Conclusions Overall, 236 regions putatively subject to recent positive selection in the cattle genome were detected. Both |iHS| and FST suggested selection in the vicinity of the Sialic acid binding Ig-like lectin 5 gene on BTA18. This region was recently reported to be a major QTL with strong effects on productive life

  2. Design of a Novel Miniaturized Frequency Selective Surface Based on 2.5-Dimensional Jerusalem Cross for 5G Applications

    Directory of Open Access Journals (Sweden)

    Peng Zhao

    2018-01-01

    Full Text Available A compact frequency selective surface (FSS for 5G applications has been designed based on 2.5-dimensional Jerusalem cross. The proposed element consists of two main parts: the successive segments of the metal traces placed alternately on the two surfaces of the substrate and the vertical vias connecting traces. Compared with previous published two-dimensional miniaturized elements, the transmission curves indicate a significant size reduction (1/26 wavelengths at the resonant frequency and exhibit good angular and polarization stabilities. Furthermore, a general equivalent circuit model is established to provide direct physical insight into the operating principle of this FSS. A prototype of the proposed FSS has been fabricated and measured, and the results validate this design.

  3. An ultrathin wide-band planar metamaterial absorber based on a fractal frequency selective surface and resistive film

    International Nuclear Information System (INIS)

    Fan Yue-Nong; Cheng Yong-Zhi; Nie Yan; Wang Xian; Gong Rong-Zhou

    2013-01-01

    We propose an ultrathin wide-band metamaterial absorber (MA) based on a Minkowski (MIK) fractal frequency selective surface and resistive film. This absorber consists of a periodic arrangement of dielectric substrates sandwiched with an MIK fractal loop structure electric resonator and a resistive film. The finite element method is used to simulate and analyze the absorption of the MA. Compared with the MA-backed copper film, the designed MA-backed resistive film exhibits an absorption of 90% at a frequency region of 2 GHz–20 GHz. The power loss density distribution of the MA is further illustrated to explain the mechanism of the proposed MA. Simulated absorptions at different incidence cases indicate that this absorber is polarization-insensitive and wide-angled. Finally, further simulated results indicate that the surface resistance of the resistive film and the dielectric constant of the substrate can affect the absorbing property of the MA. This absorber may be used in many military fields

  4. Hyper-spectral frequency selection for the classification of vegetation diseases

    OpenAIRE

    Dijkstra, Klaas; van de Loosdrecht, Jaap; Schomaker, Lambert; Wiering, Marco

    2017-01-01

    Reducing the use of pesticides by early visual detection of diseases in precision agriculture is important. Because of the color similarity between potato-plant diseases, narrow band hyper-spectral imaging is required. Payload constraints on unmanned aerial vehicles require reduc- tion of spectral bands. Therefore, we present a methodology for per-patch classification combined with hyper-spectral band selection. In controlled experiments performed on a set of individual leaves, we measure the...

  5. Pipe leak diagnostic using high frequency piezoelectric pressure sensor and automatic selection of intrinsic mode function

    Science.gov (United States)

    Yusop, Hanafi M.; Ghazali, M. F.; Yusof, M. F. M.; Remli, M. A. Pi; Kamarulzaman, M. H.

    2017-10-01

    In a recent study, the analysis of pressure transient signals could be seen as an accurate and low-cost method for leak and feature detection in water distribution systems. Transient phenomena occurs due to sudden changes in the fluid’s propagation in pipelines system caused by rapid pressure and flow fluctuation due to events such as closing and opening valves rapidly or through pump failure. In this paper, the feasibility of the Hilbert-Huang transform (HHT) method/technique in analysing the pressure transient signals in presented and discussed. HHT is a way to decompose a signal into intrinsic mode functions (IMF). However, the advantage of HHT is its difficulty in selecting the suitable IMF for the next data postprocessing method which is Hilbert Transform (HT). This paper reveals that utilizing the application of an integrated kurtosis-based algorithm for a z-filter technique (I-Kaz) to kurtosis ratio (I-Kaz-Kurtosis) allows/contributes to/leads to automatic selection of the IMF that should be used. This technique is demonstrated on a 57.90-meter medium high-density polyethylene (MDPE) pipe installed with a single artificial leak. The analysis results using the I-Kaz-kurtosis ratio revealed/confirmed that the method can be used as an automatic selection of the IMF although the noise level ratio of the signal is low. Therefore, the I-Kaz-kurtosis ratio method is recommended as a means to implement an automatic selection technique of the IMF for HHT analysis.

  6. Feature selection for neural network based defect classification of ceramic components using high frequency ultrasound.

    Science.gov (United States)

    Kesharaju, Manasa; Nagarajah, Romesh

    2015-09-01

    The motivation for this research stems from a need for providing a non-destructive testing method capable of detecting and locating any defects and microstructural variations within armour ceramic components before issuing them to the soldiers who rely on them for their survival. The development of an automated ultrasonic inspection based classification system would make possible the checking of each ceramic component and immediately alert the operator about the presence of defects. Generally, in many classification problems a choice of features or dimensionality reduction is significant and simultaneously very difficult, as a substantial computational effort is required to evaluate possible feature subsets. In this research, a combination of artificial neural networks and genetic algorithms are used to optimize the feature subset used in classification of various defects in reaction-sintered silicon carbide ceramic components. Initially wavelet based feature extraction is implemented from the region of interest. An Artificial Neural Network classifier is employed to evaluate the performance of these features. Genetic Algorithm based feature selection is performed. Principal Component Analysis is a popular technique used for feature selection and is compared with the genetic algorithm based technique in terms of classification accuracy and selection of optimal number of features. The experimental results confirm that features identified by Principal Component Analysis lead to improved performance in terms of classification percentage with 96% than Genetic algorithm with 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Tunable ultranarrow spectrum selective absorption in a graphene monolayer at terahertz frequency

    Science.gov (United States)

    Wu, Jun

    2016-06-01

    Complete absorption in a graphene monolayer at terahertz frequency through the critical coupling effect is investigated. It is achieved by sandwiching the graphene monolayer between a dielectric grating and a Bragg grating. The designed graphene absorber exhibits near-unity absorption at resonance but with an ultranarrow spectrum and antenna-like response, which is attributed to the combined effects of guided mode resonance with dielectric grating and the photonic band gap with Bragg grating. In addition to numerical simulation, the electric field distributions are also illustrated to provide a physical understanding of the perfect absorption effect. Furthermore, the absorption performance can be tuned by only changing the Fermi level of graphene, which is beneficial for real application. It is believed that this study may be useful for designing next-generation graphene-based optoelectronic devices.

  8. No effects of power line frequency extremely low frequency electromagnetic field exposure on selected neurobehavior tests of workers inspecting transformers and distribution line stations versus controls.

    Science.gov (United States)

    Li, Li; Xiong, De-fu; Liu, Jia-wen; Li, Zi-xin; Zeng, Guang-cheng; Li, Hua-liang

    2014-03-01

    We aimed to evaluate the interference of 50 Hz extremely low frequency electromagnetic field (ELF-EMF) occupational exposure on the neurobehavior tests of workers performing tour-inspection close to transformers and distribution power lines. Occupational short-term "spot" measurements were carried out. 310 inspection workers and 300 logistics staff were selected as exposure and control. The neurobehavior tests were performed through computer-based neurobehavior evaluation system, including mental arithmetic, curve coincide, simple visual reaction time, visual retention, auditory digit span and pursuit aiming. In 500 kV areas electric field intensity at 71.98% of total measured 590 spots were above 5 kV/m (national occupational standard), while in 220 kV areas electric field intensity at 15.69% of total 701 spots were above 5 kV/m. Magnetic field flux density at all the spots was below 1,000 μT (ICNIRP occupational standard). The neurobehavior score changes showed no statistical significance. Results of neurobehavior tests among different age, seniority groups showed no significant changes. Neurobehavior changes caused by daily repeated ELF-EMF exposure were not observed in the current study.

  9. Allele frequencies of variants in ultra conserved elements identify selective pressure on transcription factor binding.

    Directory of Open Access Journals (Sweden)

    Toomas Silla

    Full Text Available Ultra-conserved genes or elements (UCGs/UCEs in the human genome are extreme examples of conservation. We characterized natural variations in 2884 UCEs and UCGs in two distinct populations; Singaporean Chinese (n = 280 and Italian (n = 501 by using a pooled sample, targeted capture, sequencing approach. We identify, with high confidence, in these regions the abundance of rare SNVs (MAF5% are more often found in relatively less-conserved nucleotides within UCEs, compared to rare variants. Moreover, prevalent variants are less likely to overlap transcription factor binding site. Using SNPfold we found no significant influence of RNA secondary structure on UCE conservation. All together, these results suggest UCEs are not under selective pressure as a stretch of DNA but are under differential evolutionary pressure on the single nucleotide level.

  10. Allele frequencies of variants in ultra conserved elements identify selective pressure on transcription factor binding.

    Science.gov (United States)

    Silla, Toomas; Kepp, Katrin; Tai, E Shyong; Goh, Liang; Davila, Sonia; Catela Ivkovic, Tina; Calin, George A; Voorhoeve, P Mathijs

    2014-01-01

    Ultra-conserved genes or elements (UCGs/UCEs) in the human genome are extreme examples of conservation. We characterized natural variations in 2884 UCEs and UCGs in two distinct populations; Singaporean Chinese (n = 280) and Italian (n = 501) by using a pooled sample, targeted capture, sequencing approach. We identify, with high confidence, in these regions the abundance of rare SNVs (MAFpower for association studies. By combining our data with 1000 Genome Project data, we show in three independent datasets that prevalent UCE variants (MAF>5%) are more often found in relatively less-conserved nucleotides within UCEs, compared to rare variants. Moreover, prevalent variants are less likely to overlap transcription factor binding site. Using SNPfold we found no significant influence of RNA secondary structure on UCE conservation. All together, these results suggest UCEs are not under selective pressure as a stretch of DNA but are under differential evolutionary pressure on the single nucleotide level.

  11. Effects of bleomycin and x irradiation on the frequency of chromosomal aberrations in selected connective tissue diseases

    International Nuclear Information System (INIS)

    Burkhardt, W.C. Jr.

    1978-01-01

    Whole blood lymphocytes from 28 patients with selected connective tissue disorders (6 progressive systemic sclerosis (PSS), 6 anti-nuclear antibody positive rheumatoid arthritis, 6 anti-nuclear antibody negative rheumatoid arthritis, 6 systemic lupus erythematosus, and 4 mixed connective tissue disease) and 17 controls matched for sex, age, and race were studied to determine the frequency of spontaneous as well as bleomycin and/or x-irradiation induced chromosomal aberrations. The effects of bleomycin on cultured lymphocytes were tested, but differential susceptibilities to this clastogen were not demonstrated among the disease groups and controls investigated. However, the combined effect of bleomycin and x irradiation were found to be additive in control lymphocytes, nearly additive in PSS, RA+, and SLE cultures, but reduced considerably from the expected additive value in Ra- cultures. This study indicated that peripheral blood lymphocytes from patients with connective tissue disease, as a whole, possess greater frequencies of spontaneous chromosomal aberrations than matched controls and that x rays can produce greater frequencies of chromosomal aberrations in whole blood lymphocytes of PSS patients than in suitably matched control individuals

  12. Positive Selection of Deleterious Alleles through Interaction with a Sex-Ratio Suppressor Gene in African Buffalo: A Plausible New Mechanism for a High Frequency Anomaly

    NARCIS (Netherlands)

    Hooft, van W.F.; Greyling, B.J.; Getz, W.M.; Helden, P.D.; Zwaan, B.J.; Bastos, A.D.S.

    2015-01-01

    Although generally rare, deleterious alleles can become common through genetic drift, hitchhiking or reductions in selective constraints. Here we present a possible new mechanism that explains the attainment of high frequencies of deleterious alleles in the African buffalo (Syncerus caffer)

  13. Positive Selection of Deleterious Alleles through Interaction with a Sex-Ratio Suppressor Gene in African Buffalo: A Plausible New Mechanism for a High Frequency Anomaly

    NARCIS (Netherlands)

    Hooft, van W.F.; Greyling, B.J.; Getz, W.M.; Helden, van P.D.; Zwaan, B.J.; Bastos, A.D.S.

    2014-01-01

    Although generally rare, deleterious alleles can become common through genetic drift, hitchhiking or reductions in selective constraints. Here we present a possible new mechanism that explains the attainment of high frequencies of deleterious alleles in the African buffalo (Syncerus caffer)

  14. A 31 GHz Survey of Low-Frequency Selected Radio Sources

    Science.gov (United States)

    Mason, B. S.; Weintraub, L.; Sievers, J.; Bond, J. R.; Myers, S. T.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.

    2009-10-01

    The 100 m Robert C. Byrd Green Bank Telescope and the 40 m Owens Valley Radio Observatory telescope have been used to conduct a 31 GHz survey of 3165 known extragalactic radio sources over 143 deg2 of the sky. Target sources were selected from the NRAO VLA Sky Survey in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4 GHz flux densities of 3-10 mJy. The resulting 31 GHz catalogs are presented in full online. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4-31 GHz spectral indices of these sources, we find a mean 31-1.4 GHz flux ratio of 0.110 ± 0.003 corresponding to a spectral index of α = -0.71 ± 0.01 (S ν vprop να) 9.0% ± 0.8% of sources have α > - 0.5 and 1.2% ± 0.2% have α > 0. By combining this spectral-index distribution with 1.4 GHz source counts, we predict 31 GHz source counts in the range 1 mJy S 31) = (16.7 ± 1.7) deg-2(S 31/1 mJy)-0.80±0.07. We also assess the contribution of mJy-level (S 1.4 GHz < 3.4 mJy) radio sources to the 31 GHz cosmic microwave background power spectrum, finding a mean power of ell(ell + 1)C src ell/(2π) = 44 ± 14 μK2 and a 95% upper limit of 80 μK2 at ell = 2500. Including an estimated contribution of 12 μK2 from the population of sources responsible for the turn-up in counts below S 1.4 GHz = 1 mJy, this amounts to 21% ± 7% of what is needed to explain the CBI high-ell excess signal, 275 ± 63 μK2. These results are consistent with other measurements of the 31 GHz point-source foreground.

  15. Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation

    Directory of Open Access Journals (Sweden)

    Eduardo Mireles-Cabodevila

    2012-01-01

    Full Text Available Background. There are modes of mechanical ventilation that can select ventilator settings with computer controlled algorithms (targeting schemes. Two examples are adaptive support ventilation (ASV and mid-frequency ventilation (MFV. We studied how different clinician-chosen ventilator settings are from these computer algorithms under different scenarios. Methods. A survey of critical care clinicians provided reference ventilator settings for a 70 kg paralyzed patient in five clinical/physiological scenarios. The survey-derived values for minute ventilation and minute alveolar ventilation were used as goals for ASV and MFV, respectively. A lung simulator programmed with each scenario’s respiratory system characteristics was ventilated using the clinician, ASV, and MFV settings. Results. Tidal volumes ranged from 6.1 to 8.3 mL/kg for the clinician, 6.7 to 11.9 mL/kg for ASV, and 3.5 to 9.9 mL/kg for MFV. Inspiratory pressures were lower for ASV and MFV. Clinician-selected tidal volumes were similar to the ASV settings for all scenarios except for asthma, in which the tidal volumes were larger for ASV and MFV. MFV delivered the same alveolar minute ventilation with higher end expiratory and lower end inspiratory volumes. Conclusions. There are differences and similarities among initial ventilator settings selected by humans and computers for various clinical scenarios. The ventilation outcomes are the result of the lung physiological characteristics and their interaction with the targeting scheme.

  16. Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill.

    Science.gov (United States)

    Budde, Katharina B; González-Martínez, Santiago C; Navascués, Miguel; Burgarella, Concetta; Mosca, Elena; Lorenzo, Zaida; Zabal-Aguirre, Mario; Vendramin, Giovanni G; Verdú, Miguel; Pausas, Juli G; Heuertz, Myriam

    2017-04-01

    The recurrence of wildfires is predicted to increase due to global climate change, resulting in severe impacts on biodiversity and ecosystem functioning. Recurrent fires can drive plant adaptation and reduce genetic diversity; however, the underlying population genetic processes have not been studied in detail. In this study, the neutral and adaptive evolutionary effects of contrasting fire regimes were examined in the keystone tree species Pinus halepensis Mill. (Aleppo pine), a fire-adapted conifer. The genetic diversity, demographic history and spatial genetic structure were assessed at local (within-population) and regional scales for populations exposed to different crown fire frequencies. Eight natural P. halepensis stands were sampled in the east of the Iberian Peninsula, five of them in a region exposed to frequent crown fires (HiFi) and three of them in an adjacent region with a low frequency of crown fires (LoFi). Samples were genotyped at nine neutral simple sequence repeats (SSRs) and at 251 single nucleotide polymorphisms (SNPs) from coding regions, some of them potentially important for fire adaptation. Fire regime had no effects on genetic diversity or demographic history. Three high-differentiation outlier SNPs were identified between HiFi and LoFi stands, suggesting fire-related selection at the regional scale. At the local scale, fine-scale spatial genetic structure (SGS) was overall weak as expected for a wind-pollinated and wind-dispersed tree species. HiFi stands displayed a stronger SGS than LoFi stands at SNPs, which probably reflected the simultaneous post-fire recruitment of co-dispersed related seeds. SNPs with exceptionally strong SGS, a proxy for microenvironmental selection, were only reliably identified under the HiFi regime. An increasing fire frequency as predicted due to global change can promote increased SGS with stronger family structures and alter natural selection in P. halepensis and in plants with similar life history traits

  17. An iterative detection method of MIMO over spatial correlated frequency selective channel: using list sphere decoding for simplification

    Science.gov (United States)

    Shi, Zhiping; Yan, Bing

    2010-08-01

    In multiple-input multiple-output(MIMO) wireless systems, combining good channel codes(e.g., Non-binary Repeat Accumulate codes) with adaptive turbo equalization is a good option to get better performance and lower complexity under Spatial Correlated Frequency Selective(SCFS) Channel. The key of this method is after joint antennas MMSE detection (JAD/MMSE) based on interruption cancelling using soft information, considering the detection result as an output of a Gaussian equivalent flat fading channel, and performing maximum likelihood detection(ML) to get more correct estimated result. But the using of ML brings great complexity increase, which is not allowed. In this paper, a low complexity method called list sphere decoding is introduced and applied to replace the ML in order to simplify the adaptive iterative turbo equalization system.

  18. Selective increase of in vivo firing frequencies in DA SN neurons after proteasome inhibition in the ventral midbrain.

    Science.gov (United States)

    Subramaniam, Mahalakshmi; Kern, Beatrice; Vogel, Simone; Klose, Verena; Schneider, Gaby; Roeper, Jochen

    2014-09-01

    The impairment of protein degradation via the ubiquitin-proteasome system (UPS) is present in sporadic Parkinson's disease (PD), and might play a key role in selective degeneration of vulnerable dopamine (DA) neurons in the substantia nigra pars compacta (SN). Further evidence for a causal role of dysfunctional UPS in familial PD comes from mutations in parkin, which results in a loss of function of an E3-ubiquitin-ligase. In a mouse model, genetic inactivation of an essential component of the 26S proteasome lead to widespread neuronal degeneration including DA midbrain neurons and the formation of alpha-synuclein-positive inclusion bodies, another hallmark of PD. Studies using pharmacological UPS inhibition in vivo had more mixed results, varying from extensive degeneration to no loss of DA SN neurons. However, it is currently unknown whether UPS impairment will affect the neurophysiological functions of DA midbrain neurons. To answer this question, we infused a selective proteasome inhibitor into the ventral midbrain in vivo and recorded single DA midbrain neurons 2 weeks after the proteasome challenge. We found a selective increase in the mean in vivo firing frequencies of identified DA SN neurons in anesthetized mice, while those in the ventral tegmental area (VTA) were unaffected. Our results demonstrate that a single-hit UPS inhibition is sufficient to induce a stable and selective hyperexcitability phenotype in surviving DA SN neurons in vivo. This might imply that UPS dysfunction sensitizes DA SN neurons by enhancing 'stressful pacemaking'. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  19. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  20. Evaluation of the Relative Validity of the Short Diet Questionnaire for Assessing Usual Consumption Frequencies of Selected Nutrients and Foods

    Directory of Open Access Journals (Sweden)

    Bryna Shatenstein

    2015-08-01

    Full Text Available A 36-item Short Diet Questionnaire (SDQ was developed to assess usual consumption frequencies of foods providing fats, fibre, calcium, vitamin D, in addition to fruits and vegetables. It was pretested among 30 community-dwelling participants from the Québec Longitudinal Study on Nutrition and Successful Aging, “NuAge” (n = 1793, 52.4% women, recruited in three age groups (70 ± 2 years; 75 ± 2 years; 80 ± 2 years. Following revision, the SDQ was administered to 527 NuAge participants (55% female, distributed among the three age groups, both sexes and languages (French, English prior to the second of three non-consecutive 24 h diet recalls (24HR and validated relative to the mean of three 24HR. Full data were available for 396 participants. Most SDQ nutrients and fruit and vegetable servings were lower than 24HR estimates (p < 0.05 except calcium, vitamin D, and saturated and trans fats. Spearman correlations between the SDQ and 24HR were modest and significant (p < 0.01, ranging from 0.19 (cholesterol to 0.45 (fruits and vegetables. Cross-classification into quartiles showed 33% of items were jointly classified into identical quartiles of the distribution, 73% into identical and contiguous quartiles, and only 7% were frankly misclassified. The SDQ is a reasonably accurate, rapid approach for ranking usual frequencies of selected nutrients and foods. Further testing is needed in a broader age range.

  1. Mathematical Model and Computational Analysis of Selected Transient States of Cylindrical Linear Induction Motor Fed via Frequency Converter

    Directory of Open Access Journals (Sweden)

    Andrzej Rusek

    2008-01-01

    Full Text Available The mathematical model of cylindrical linear induction motor (C-LIM fed via frequency converter is presented in the paper. The model was developed in order to analyze numerically the transient states. Problems concerning dynamics of ac-machines especially linear induction motor are presented in [1 – 7]. Development of C-LIM mathematical model is based on circuit method and analogy to rotary induction motor. The analogy between both: (a stator and rotor windings of rotary induction motor and (b winding of primary part of C-LIM (inductor and closed current circuits in external secondary part of C-LIM (race is taken into consideration. The equations of C-LIM mathematical model are presented as matrix together with equations expressing each vector separately. A computational analysis of selected transient states of C-LIM fed via frequency converter is presented in the paper. Two typical examples of C-LIM operation are considered for the analysis: (a starting the motor at various static loads and various synchronous velocities and (b reverse of the motor at the same operation conditions. Results of simulation are presented as transient responses including transient electromagnetic force, transient linear velocity and transient phase current.

  2. Biperiodic oscillatory coupling with the thickness of an embedded Ni layer in Co/Cu/Co/Ni/Co (100) and selection rules for the periods

    NARCIS (Netherlands)

    de Vries, J.J.; Vorst, van de M.T.H.; Johnson, M.T.; Jungblut, R.; Reinders, A.; Bloemen, P.J.H.; Coehoorn, R.; Jonge, de W.J.M.

    1996-01-01

    A biperiodic oscillation of the strength of the antiferromagnetic interlayer coupling as a function of the thickness of an embedded Ni layer has been observed in an epitaxial Cu(100)/Co/Cu/Co/Ni/Co sample with the Cu interlayer and the Ni layer in the form of wedges. As the effect originates from

  3. Determination of bromine in selected polymer materials by a wavelength-dispersive X-ray fluorescence spectrometric method - Critical thickness problem and solutions

    Science.gov (United States)

    Gorewoda, Tadeusz; Mzyk, Zofia; Anyszkiewicz, Jacek; Charasińska, Jadwiga

    2015-04-01

    The purpose of this study was to develop an accurate method for the determination of bromine in polymer materials using X-ray fluorescence spectrometry when the thickness of the sample is less than the bromine critical thickness (tc) value. This is particularly important for analyzing compliance with the Restriction of Hazardous Substances Directive. Mathematically and experimentally estimated tc values in polyethylene and cellulose matrixes were up to several millimeters. Four methods were developed to obtain an accurate result. These methods include the addition of an element with a high mass absorption coefficient, the measurement of the total bromine contained in a defined volume of the sample, the exploitation of tube-Rayleigh line intensities and using the Br-Lβ line.

  4. Thick melanoma in Tuscany.

    Science.gov (United States)

    Chiarugi, Alessandra; Nardini, Paolo; Borgognoni, Lorenzo; Brandani, Paola; Gerlini, Gianni; Rubegni, Pietro; Lamberti, Arianna; Salvini, Camilla; Lo Scocco, Giovanni; Cecchi, Roberto; Sirna, Riccardo; Lorenzi, Stefano; Gattai, Riccardo; Battistini, Silvio; Crocetti, Emanuele

    2017-03-14

    The epidemiologic trends of cutaneous melanoma are similar in several countries with a Western-type life style, where there is a progressive increasing incidence and a low but not decreasing mor- tality, or somewhere an increase too, especially in the older age groups. Also in Tuscany there is a steady rise in incidence with prevalence of in situ and invasive thin melanomas, with also an increase of thick melanomas. It is necessary to reduce the frequency of thick melanomas to reduce specific mortality. The objective of the current survey has been to compare, in the Tuscany population, by a case- case study, thin and thick melanoma cases, trying to find out those personal and tumour characteristics which may help to customize preventive interventions. RESULTS The results confirmed the age and the lower edu- cation level are associated with a later detection. The habit to perform skin self-examination is resulted protec- tive forward thick melanoma and also the diagnosis by a doctor. The elements emerging from the survey allow to hypothesize a group of subjects resulting at higher risk for a late diagnosis, aged over 50 and carrier of a fewer constitutional and environmental risk factors: few total and few atypical nevi, and lower sun exposure and burning. It is assumable that a part of people did not be reached from messages of prevention because does not recognize oneself in the categories of people at risk for skin cancers described in educational cam- paigns. If we want to obtain better results on diagnosis of skin melanoma we have to think a new strategy. At least to think over the educational messages discriminating people more at risk of incidence of melanoma from people more at risk to die from melanoma, and to renewed active involvement of the Gen- eral Practitioners .

  5. Electropolymerization of pyrrole on oxidizable metal under high frequency ultrasound irradiation. Application of focused beam to a selective masking technique

    Energy Technology Data Exchange (ETDEWEB)

    Et Taouil, A. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Lallemand, F., E-mail: fabrice.lallemand@univ-fcomte.f [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Hallez, L.; Hihn, J-Y. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France)

    2010-12-01

    A novel masking technique against polymer deposition based on High Intensity Focused Ultrasound (HIFU) irradiation was developed for the first time. With this in mind, a variety of background salts were tested. Sodium salicylate was found to be the most effective electrolytic medium for pyrrole sonoelectropolymerization on copper as it leads to a very efficient passivating oxide layer preventing copper dissolution while enabling polymer formation independently from sonication. In such a medium, high frequency ultrasound greatly refines surface structure, and a slight increase in doping level is observed. Finally, it was proved that focused ultrasound increases copper dissolution in sodium oxalate electrolyte while preventing polypyrrole deposition. A selected zone on the copper substrate was thus irradiated by the focused ultrasound beam to protect it from polymerization. In a second stage, a self-assembled monolayer was deposited on this polymer-free area to create a surface biphased substrate. This type of masking technique can be proposed as an interesting alternative to lithography as it is easier to carry out and allows chemical waste reduction.

  6. Space-Time Joint Interference Cancellation Using Fuzzy-Inference-Based Adaptive Filtering Techniques in Frequency-Selective Multipath Channels

    Science.gov (United States)

    Hu, Chia-Chang; Lin, Hsuan-Yu; Chen, Yu-Fan; Wen, Jyh-Horng

    2006-12-01

    An adaptive minimum mean-square error (MMSE) array receiver based on the fuzzy-logic recursive least-squares (RLS) algorithm is developed for asynchronous DS-CDMA interference suppression in the presence of frequency-selective multipath fading. This receiver employs a fuzzy-logic control mechanism to perform the nonlinear mapping of the squared error and squared error variation, denoted by ([InlineEquation not available: see fulltext.],[InlineEquation not available: see fulltext.]), into a forgetting factor[InlineEquation not available: see fulltext.]. For the real-time applicability, a computationally efficient version of the proposed receiver is derived based on the least-mean-square (LMS) algorithm using the fuzzy-inference-controlled step-size[InlineEquation not available: see fulltext.]. This receiver is capable of providing both fast convergence/tracking capability as well as small steady-state misadjustment as compared with conventional LMS- and RLS-based MMSE DS-CDMA receivers. Simulations show that the fuzzy-logic LMS and RLS algorithms outperform, respectively, other variable step-size LMS (VSS-LMS) and variable forgetting factor RLS (VFF-RLS) algorithms at least 3 dB and 1.5 dB in bit-error-rate (BER) for multipath fading channels.

  7. Space-Time Joint Interference Cancellation Using Fuzzy-Inference-Based Adaptive Filtering Techniques in Frequency-Selective Multipath Channels

    Directory of Open Access Journals (Sweden)

    Chen Yu-Fan

    2006-01-01

    Full Text Available An adaptive minimum mean-square error (MMSE array receiver based on the fuzzy-logic recursive least-squares (RLS algorithm is developed for asynchronous DS-CDMA interference suppression in the presence of frequency-selective multipath fading. This receiver employs a fuzzy-logic control mechanism to perform the nonlinear mapping of the squared error and squared error variation, denoted by ( , , into a forgetting factor . For the real-time applicability, a computationally efficient version of the proposed receiver is derived based on the least-mean-square (LMS algorithm using the fuzzy-inference-controlled step-size . This receiver is capable of providing both fast convergence/tracking capability as well as small steady-state misadjustment as compared with conventional LMS- and RLS-based MMSE DS-CDMA receivers. Simulations show that the fuzzy-logic LMS and RLS algorithms outperform, respectively, other variable step-size LMS (VSS-LMS and variable forgetting factor RLS (VFF-RLS algorithms at least 3 dB and 1.5 dB in bit-error-rate (BER for multipath fading channels.

  8. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Directory of Open Access Journals (Sweden)

    Markus Dietrich

    2017-07-01

    Full Text Available The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13 was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  9. Radio-Frequency-Based NH₃-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences.

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-07-12

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH₃ storage control, the influence of the storage degree on the catalyst performance, i.e., on NO x conversion and NH₃ slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH₃ storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  10. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-01-01

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. PMID:28704929

  11. Frequency-selective near-field radiative heat transfer between photonic crystal slabs: a computational approach for arbitrary geometries and materials.

    Science.gov (United States)

    Rodriguez, Alejandro W; Ilic, Ognjen; Bermel, Peter; Celanovic, Ivan; Joannopoulos, John D; Soljačić, Marin; Johnson, Steven G

    2011-09-09

    We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic-crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab-slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the nonsymmorphic symmetry group.

  12. [Relation between frequency modulation direction selectivity and forward masking of inferior collicular neurons: a study on in vivo intracellular recording in mice].

    Science.gov (United States)

    Fu, Zi-Ying; Zeng, Hong; Tang, Jia; Li, Jie; Li, Juan; Chen, Qi-Cai

    2013-06-25

    It has been reported that the frequency modulation (FM) or FM direction sensitivity and forward masking of central auditory neurons are related with the neural inhibition, but there are some arguments, because no direct evidence of inhibitory synaptic input was obtained in previous studies using extracellular recording. In the present study, we studied the relation between FM direction sensitivity and forward masking of the inferior collicular (IC) neurons using in vivo intracellular recordings in 20 Mus musculus Km mice. Thirty seven with complete data among 93 neurons were analyzed and discussed. There was an inhibitory area which consisted of inhibitory postsynaptic potentials (IPSP) at high frequency side of frequency tuning of up-sweep FM (FMU) sensitive neurons (n = 12) and at low frequency side of frequency tuning of down-sweep FM (FMD) selective neurons (n = 8), while there was no any inhibitory area at both sides of frequency tuning of non-FM sweep direction (FMN) sensitive neurons (n = 17). Therefore, these results show that the inhibitory area at low or high frequency side of frequency tuning is one of the mechanisms for forming FM sweep direction sensitivity of IC neurons. By comparison of forward masking produced by FMU and FMD sound stimuli in FMU, FMD and FMN neurons, the selective FM sounds could produce stronger forward masking than the non-selective in FMU and FMD neurons, while there was no forward masking difference between FMU and FMD stimuli in the FMN neurons. We suggest that the post-action potential IPSP is a potential mechanism for producing stronger forward masking in FMU and FMD neurons.

  13. Across-environment genetic correlations and the frequency of selective environments shape the evolutionary dynamics of growth rate in Impatiens capensis.

    Science.gov (United States)

    Stinchcombe, John R; Izem, Rima; Heschel, M Shane; McGoey, Brechann V; Schmitt, Johanna

    2010-10-01

    Trade-offs can exist within and across environments, and constrain evolutionary trajectories. To examine the effects of competition and resource availability on trade-offs, we grew individuals of recombinant inbred lines of Impatiens capensis in a factorial combination of five densities with two light environments (full light and neutral shade) and used a Bayesian logistic growth analysis to estimate intrinsic growth rates. To estimate across-environment constraints, we developed a variance decomposition approach to principal components analysis, which accounted for sample size, model-fitting, and within-RIL variation prior to eigenanalysis. We detected negative across-environment genetic covariances in intrinsic growth rates, although only under full-light. To evaluate the potential importance of these covariances, we surveyed natural populations of I. capensis to measure the frequency of different density environments across space and time. We combined our empirical estimates of across-environment genetic variance-covariance matrices and frequency of selective environments with hypothetical (yet realistic) selection gradients to project evolutionary responses in multiple density environments. Selection in common environments can lead to correlated responses to selection in rare environments that oppose and counteract direct selection in those rare environments. Our results highlight the importance of considering both the frequency of selective environments and the across-environment genetic covariances in traits simultaneously. © 2010 The Author(s). Journal compilation © 2010 The Society for the Study of Evolution.

  14. Isotope-selective dissociation of the OsO4 molecule by two pulses of infrared radiation at different frequencies

    International Nuclear Information System (INIS)

    Ambartzumian, R.V.; Furzikov, N.P.; Gorokhov, Y.A.; Letokhov, V.S.; Makarov, G.N.; Puretzky, A.A.

    1977-01-01

    The dissociation of the OsO 4 molecule in a two-frequency infrared laser field has been investigated. A twentyfold increase in the dissociation rate was obtained when the dissociation frequency was shifted to the ''red'' side of the linear absorption spectrum of OsO 4 . Osmium isotope separation was carried out by this two-frequency method. Optimal conditions for a scalable isotope separation process have been formulated

  15. Quantification of thickness loss in a liquid-loaded plate using ultrasonic guided wave tomography

    Science.gov (United States)

    Rao, Jing; Ratassepp, Madis; Fan, Zheng

    2017-12-01

    Ultrasonic guided wave tomography (GWT) provides an attractive solution to map thickness changes from remote locations. It is based on the velocity-to-thickness mapping employing the dispersive characteristics of selected guided modes. This study extends the application of GWT on a liquid-loaded plate. It is a more challenging case than the application on a free plate, due to energy of the guided waves leaking into the liquid. In order to ensure the accuracy of thickness reconstruction, advanced forward models are developed to consider attenuation effects using complex velocities. The reconstruction of the thickness map is based on the frequency-domain full waveform inversion (FWI) method, and its accuracy is discussed using different frequencies and defect dimensions. Validation experiments are carried out on a water-loaded plate with an irregularly shaped defect using S0 guided waves, showing excellent performance of the reconstruction algorithm.

  16. Frequency selectivity in pulse responses of Pt/poly(3-hexylthiophene-2,5-diyl/polyethylene oxide +Li+/Pt hetero-junction.

    Directory of Open Access Journals (Sweden)

    Fei Zeng

    Full Text Available Pt/poly(3-hexylthiophene-2,5-diyl/polyethylene oxide + Li+/Pt hetero junctions were fabricated, and their pulse responses were studied. The direct current characteristics were not symmetric in the sweeping range of ±2 V. Negative differential resistance appeared in the input range of 0 to 2 V because of de-doping (or reduction in the side with the semiconductor layer. The device responded stably to a train of pulses with a fixed frequency. The inverse current after a pulse was related to the back-migrated ions. Importantly, the weight calculated based on the inverse current strength, was depressed during low-frequency stimulations but was potentiated during high-frequency stimulations when pulses were positive. Therefore, frequency selectivity was first observed in a semiconducting polymer/electrolyte hetero junction. Detailed analysis of the pulse response showed that the input frequency could modulate the timing of ion doping, de-doping, and re-doping at the semiconducting polymer/electrolyte interface, which then resulted in the frequency selectivity. Our study suggests that the simple redox process in semiconducting polymers can be modulated and used in signal handling or the simulation of bio-learning.

  17. Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

    Science.gov (United States)

    Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

    2018-01-01

    Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

  18. Second harmonic generation of frequency-locked pulsed dye laser for selective photoionization of T1-203 isotope

    International Nuclear Information System (INIS)

    Lim, Gwon; Jeong, Do Young; Ko, Kwang Hoon; Kim, Jae Woo; Kim, Taek Soo; Rho, Sipyo; Kim, Cheol Jung

    2003-01-01

    We have constructed the frequency-locked pulsed dye laser system. It is composed with a GIM-type oscillator and 3 stage longitudinally pumped amplifiers. The pump laser is the second harmonic of pulse Nd:YAG laser at the repetition rate of 6 kHz. Frequency-locking of dye laser oscillator is actively controlled by the feedback loop between a photoionization signal of T1-203 isotope and a wavelength tuning control. The tuning mirror rotates the order of micro degree per a step of step motor. Feedback system for frequency locking is operated with a PC-based control interface, including the data analysis of photoionization signals and the wavelength control using step pumping method for a medical application. Therefor, the dye laser has to be locked at 583.66 nm for SHG or BBO crystal. With the frequency-locking system, the photoionization experiment has been done for more than 10 hours.

  19. Non-contact radiation thickness gauge

    International Nuclear Information System (INIS)

    Tsujii, T.; Okino, T.

    1983-01-01

    A noncontact thickness gauge system for measuring the thickness of a material comprising a source of radiation, a detector for detecting the amount of radiation transmitted through the material which is a function of the absorptance and thickness of the material, a memory for storing the output signals of the detector and curve-defining parameters for a plurality of quadratic calibration curves which correspond to respective thickness ranges, and a processor for processing the signals and curve defining parameters to determine the thickness of the material. Measurements are made after precalibration to obtain calibration curves and these are stored in the memory, providing signals representative of a nominal thickness and an alloy compensation coefficient for the material. The calibration curve corresponding to a particular thickness range is selected and the curve compensated for drift; the material is inserted into the radiation path and the detector output signal processed with the compensated calibration curve to determine the thickness of the material. (author)

  20. Inferring Allele Frequency Trajectories from Ancient DNA Indicates That Selection on a Chicken Gene Coincided with Changes in Medieval Husbandry Practices.

    Science.gov (United States)

    Loog, Liisa; Thomas, Mark G; Barnett, Ross; Allen, Richard; Sykes, Naomi; Paxinos, Ptolemaios D; Lebrasseur, Ophélie; Dobney, Keith; Peters, Joris; Manica, Andrea; Larson, Greger; Eriksson, Anders

    2017-08-01

    Ancient DNA provides an opportunity to infer the drivers of natural selection by linking allele frequency changes to temporal shifts in environment or cultural practices. However, analyses have often been hampered by uneven sampling and uncertainties in sample dating, as well as being confounded by demographic processes. Here, we present a Bayesian statistical framework for quantifying the timing and strength of selection using ancient DNA that explicitly addresses these challenges. We applied this method to time series data for two loci: TSHR and BCDO2, both hypothesised to have undergone strong and recent selection in domestic chickens. The derived variant in TSHR, associated with reduced aggression to conspecifics and faster onset of egg laying, shows strong selection beginning around 1,100 years ago, coincident with archaeological evidence for intensified chicken production and documented changes in egg and chicken consumption. To our knowledge, this is the first example of preindustrial domesticate trait selection in response to a historically attested cultural shift in food preference. For BCDO2, we find support for selection, but demonstrate that the recent rise in allele frequency could also have been driven by gene flow from imported Asian chickens during more recent breed formations. Our findings highlight that traits found ubiquitously in modern domestic species may not necessarily have originated during the early stages of domestication. In addition, our results demonstrate the importance of precise estimation of allele frequency trajectories through time for understanding the drivers of selection. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  1. Island biology and morphological divergence of the Skyros wall lizard Podarcis gaigeae: a combined role for local selection and genetic drift on color morph frequency divergence?

    Directory of Open Access Journals (Sweden)

    Runemark Anna

    2010-09-01

    Full Text Available Abstract Background Patterns of spatial variation in discrete phenotypic traits can be used to draw inferences about the adaptive significance of traits and evolutionary processes, especially when compared to patterns of neutral genetic variation. Population divergence in adaptive traits such as color morphs can be influenced by both local ecology and stochastic factors such as genetic drift or founder events. Here, we use quantitative color measurements of males and females of Skyros wall lizard, Podarcis gaigeae, to demonstrate that this species is polymorphic with respect to throat color, and the morphs form discrete phenotypic clusters with limited overlap between categories. We use divergence in throat color morph frequencies and compare that to neutral genetic variation to infer the evolutionary processes acting on islet- and mainland populations. Results Geographically close islet- and mainland populations of the Skyros wall lizard exhibit strong divergence in throat color morph frequencies. Population variation in throat color morph frequencies between islets was higher than that between mainland populations, and the effective population sizes on the islets were small (Ne:s ST for throat color morph frequencies fell within the neutral FST-distribution estimated from microsatellite markers, and genetic drift could thus not be rejected as an explanation for the pattern. Moreover, for both comparisons among mainland-mainland population pairs and between mainland-islet population pairs, morph frequency divergence was significantly correlated with neutral divergence, further pointing to some role for genetic drift in divergence also at the phenotypic level of throat color morphs. Conclusions Genetic drift could not be rejected as an explanation for the pattern of population divergence in morph frequencies. In spite of an expected stabilising selection, throat color frequencies diverged in the islet populations. These results suggest that

  2. Pupil Dilation and EEG Alpha Frequency Band Power Reveal Load on Executive Functions for Link-Selection Processes during Text Reading.

    Directory of Open Access Journals (Sweden)

    Christian Scharinger

    Full Text Available Executive working memory functions play a central role in reading comprehension. In the present research we were interested in additional load imposed on executive functions by link-selection processes during computer-based reading. For obtaining process measures, we used a methodology of concurrent electroencephalographic (EEG and eye-tracking data recording that allowed us to compare epochs of pure text reading with epochs of hyperlink-like selection processes in an online reading situation. Furthermore, this methodology allowed us to directly compare the two physiological load-measures EEG alpha frequency band power and pupil dilation. We observed increased load on executive functions during hyperlink-like selection processes on both measures in terms of decreased alpha frequency band power and increased pupil dilation. Surprisingly however, the two measures did not correlate. Two additional experiments were conducted that excluded potential perceptual, motor, or structural confounds. In sum, EEG alpha frequency band power and pupil dilation both turned out to be sensitive measures for increased load during hyperlink-like selection processes in online text reading.

  3. Card controlled beta backscatter thickness measuring instrument

    International Nuclear Information System (INIS)

    Schlesinger, J.

    1978-01-01

    An improved beta backscatter instrument for the nondestructive measurement of the thickness of thin coatings on a substrate is described. Included therein is the utilization of a bank of memory stored data representative of isotope, substrate, coating material and thickness range characteristics in association with a control card having predetermined indicia thereon selectively representative of a particular isotope, substrate material, coating material and thickness range for conditioning electronic circuit means by memory stored data selected in accord with the predetermined indicia on a control card for converting backscattered beta particle counts into indicia of coating thickness

  4. Retrieval of ice thickness from polarimetric SAR data

    Science.gov (United States)

    Kwok, R.; Yueh, S. H.; Nghiem, S. V.; Huynh, D. D.

    1993-01-01

    We describe a potential procedure for retrieving ice thickness from multi-frequency polarimetric SAR data for thin ice. This procedure includes first masking out the thicker ice types with a simple classifier and then deriving the thickness of the remaining pixels using a model-inversion technique. The technique used to derive ice thickness from polarimetric observations is provided by a numerical estimator or neural network. A three-layer perceptron implemented with the backpropagation algorithm is used in this investigation with several improved aspects for a faster convergence rate and a better accuracy of the neural network. These improvements include weight initialization, normalization of the output range, the selection of offset constant, and a heuristic learning algorithm. The performance of the neural network is demonstrated by using training data generated by a theoretical scattering model for sea ice matched to the database of interest. The training data are comprised of the polarimetric backscattering coefficients of thin ice and the corresponding input ice parameters to the scattering model. The retrieved ice thickness from the theoretical backscattering coefficients is compare with the input ice thickness to the scattering model to illustrate the accuracy of the inversion method. Results indicate that the network convergence rate and accuracy are higher when multi-frequency training sets are presented. In addition, the dominant backscattering coefficients in retrieving ice thickness are found by comparing the behavior of the network trained backscattering data at various incidence angels. After the neural network is trained with the theoretical backscattering data at various incidence anges, the interconnection weights between nodes are saved and applied to the experimental data to be investigated. In this paper, we illustrate the effectiveness of this technique using polarimetric SAR data collected by the JPL DC-8 radar over a sea ice scene.

  5. A new method for selectively enhancing hemisphere processing: voice frequency amplification influences the strength of attribute framing.

    Science.gov (United States)

    McCormick, Michael; Seta, John J

    2012-01-01

    An attribute framing effect occurs when positive or negative associations produced by positive or negative frames are mapped onto evaluations resulting in a more favourable evaluation for the positively framed attribute. We used a new voice frequency manipulation to differentially enhance right versus left hemisphere processing. In doing so we found a strong attribute framing effect when a speaker with a low-frequency voice enhanced the contextual processing style of the right hemisphere. However, a framing effect was not obtained when a speaker with a high-frequency voice enhanced the inferential/analytical processing style of the left hemisphere. At the theoretical level our results provide evidence that the contextual processing style of the right hemisphere is especially susceptible to associative implications, such as those found in attribute framing manipulations. At the applied level we provide a simple method for altering the effectiveness of persuasion messages.

  6. Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations.

    Science.gov (United States)

    Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

    2017-09-15

    The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

  7. Selective Dirac voltage engineering of individual graphene field-effect transistors for digital inverter and frequency multiplier integrations

    Science.gov (United States)

    Sul, Onejae; Kim, Kyumin; Jung, Yungwoo; Choi, Eunsuk; Lee, Seung-Beck

    2017-09-01

    The ambipolar band structure of graphene presents unique opportunities for novel electronic device applications. A cycle of gate voltage sweep in a conventional graphene transistor produces a frequency-doubled output current. To increase the frequency further, we used various graphene doping control techniques to produce Dirac voltage engineered graphene channels. The various surface treatments and substrate conditions produced differently doped graphene channels that were integrated on a single substrate and multiple Dirac voltages were observed by applying a single gate voltage sweep. We applied the Dirac voltage engineering techniques to graphene field-effect transistors on a single chip for the fabrication of a frequency multiplier and a logic inverter demonstrating analog and digital circuit application possibilities.

  8. Reduced feedback selective cluster index scheduling with user pre-selection for next-generation multi-input multi-output orthogonal frequency division multiple access system

    OpenAIRE

    Nicolaou, M; Doufexi, A; Armour, SMD; Sun, Y

    2011-01-01

    The joint use of opportunistic scheduling and orthogonal frequency division multiple access (OFDMA) provide significant gains in environments of low mobility and scatter for which channel variations are low. The downside of opportunistic scheduling in multicarrier systems such as OFDMA, lies in the substantial uplink overhead required to feed back by the mobile stations (MSs) describing users' instantaneous link conditions. This study presents a novel approach towards multicarrier opportunist...

  9. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-01-01

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected

  10. The Adaptive Change of HLA-DRB1 Allele Frequencies Caused by Natural Selection in a Mongolian Population That Migrated to the South of China.

    Directory of Open Access Journals (Sweden)

    Hao Sun

    Full Text Available Pathogen-driven balancing selection determines the richness of human leukocyte antigen (HLA alleles. Changes in the pathogen spectrum may cause corresponding changes in HLA loci. Approximately 700 years ago, a Mongolian population moved from the north of China to the Yunnan region in the south of China. The pathogen spectrum in the south of China differs from that in the north. In this study, changes in the HLA genes in the Yunnan Mongolian population, as well as the underlying mechanism, were investigated. A sequence-based typing method (SBT was used to genotype HLA-DRB1 in 470 individuals from two Mongolian populations and another five ethnic groups. Meanwhile, 10 autosomal short tandem repeats (STRs were genotyped to assess the influence of genetic background on HLA-DRB1 frequencies. The frequencies of certain alleles changed significantly in the Mongolian population that migrated to Yunnan. For example, DRB1*12:02:01 increased from 6.1% to 35.4%. STR analysis excluded the possibility of a recent bottleneck and indicated that 50% of the genetic consistency between northern and southern Mongolians; Tajima's D value for HLA-DRB1 exon2 and dN/dS analysis showed that the HLA-DRB1 genes in both Mongolian populations were under balancing selection. However, the sites under natural selection changed. We proposed that the dramatically change of HLA frequencies in southern Mongolian was caused by a combination of inter-population gene flow and natural selection. Certain diseases specific to the south of China, such as malaria, may be the driving force behind the enhanced DRB1*12:02:01 frequency.

  11. Selective Harmonic Elimination in Asymmetric Cascaded Multilevel Inverters Using a New Low-frequency Strategy for Photovoltaic Applications

    DEFF Research Database (Denmark)

    Dowlatabadi, Mohammadkazem Bakhshizadeh; Iman-Eini, Hossein; Blaabjerg, Frede

    2015-01-01

    Asymmetric multilevel inverters with a main and auxiliary power circuit can yield maximum number of voltage levels against the number of semiconductor devices. Most of the output power will be produced by the main inverter, which works at low frequency and the auxiliary inverters only improve the...

  12. Extraordinary electromagnetic transmission by antenna arrays and frequency selective surfaces having compound unit cells with dissimilar elements

    Energy Technology Data Exchange (ETDEWEB)

    Loui, Hung; Strassner, II, Bernd H.

    2018-03-20

    The various embodiments presented herein relate to extraordinary electromagnetic transmission (EEMT) to enable multiple inefficient (un-matched) but coupled radiators and/or apertures to radiate and/or pass electromagnetic waves efficiently. EEMT can be utilized such that signal transmission from a plurality of antennas and/or apertures occurs at a transmission frequency different to transmission frequencies of the individual antennas and/or aperture elements. The plurality of antennas/apertures can comprise first antenna/aperture having a first radiating area and material(s) and second antenna/aperture having a second radiating area and material(s), whereby the first radiating/aperture area and second radiating/aperture area can be co-located in a periodic compound unit cell. Owing to mutual coupling between the respective antennas/apertures in their arrayed configuration, the transmission frequency of the array can be shifted from the transmission frequencies of the individual elements. EEMT can be utilized for an array of evanescent of inefficient radiators connected to a transmission line(s).

  13. Frequency-selectivity of a thalamocortical relay neuron during Parkinson's disease and deep brain stimulation: a computational study

    NARCIS (Netherlands)

    Cagnan, Hayriye; Cagnan, H.; Meijer, Hil Gaétan Ellart; van Gils, Stephanus A.; Krupa, M.; Heida, Tjitske; Rudolph, Michelle; Wadman, Wyse J.; Martens, Hubert C.F.

    2009-01-01

    In this computational study, we investigated (i) the functional importance of correlated basal ganglia (BG) activity associated with Parkinson's disease (PD) motor symptoms by analysing the effects of globus pallidus internum (GPi) bursting frequency and synchrony on a thalamocortical (TC) relay

  14. Highly selective etching of silicon nitride to physical-vapor-deposited a-C mask in dual-frequency capacitively coupled CH2F2/H2 plasmas

    International Nuclear Information System (INIS)

    Kim, J. S.; Kwon, B. S.; Heo, W.; Jung, C. R.; Park, J. S.; Shon, J. W.; Lee, N.-E.

    2010-01-01

    A multilevel resist (MLR) structure can be fabricated based on a very thin amorphous carbon (a-C) layer ( congruent with 80 nm) and Si 3 N 4 hard-mask layer ( congruent with 300 nm). The authors investigated the selective etching of the Si 3 N 4 layer using a physical-vapor-deposited (PVD) a-C mask in a dual-frequency superimposed capacitively coupled plasma etcher by varying the process parameters in the CH 2 F 2 /H 2 /Ar plasmas, viz., the etch gas flow ratio, high-frequency source power (P HF ), and low-frequency source power (P LF ). They found that under certain etch conditions they obtain infinitely high etch selectivities of the Si 3 N 4 layers to the PVD a-C on both the blanket and patterned wafers. The etch gas flow ratio played a critical role in determining the process window for infinitely high Si 3 N 4 /PVD a-C etch selectivity because of the change in the degree of polymerization. The etch results of a patterned ArF photoresisit/bottom antireflective coating/SiO x /PVD a-C/Si 3 N 4 MLR structure supported the idea of using a very thin PVD a-C layer as an etch-mask layer for the Si 3 N 4 hard-mask pattern with a pattern width of congruent with 80 nm and high aspect ratio of congruent with 5.

  15. Assessment of Radio-Frequency Radiation Exposure Level from Selected Mobile Base Stations (MBS) in Lokoja, Kogi State, Nigeria

    OpenAIRE

    Nwankwo, U. J. Victor; Jibiri, N. N.; Dada, S. S.; Onugba, A. A.; Ushie, P.

    2012-01-01

    The acquisition and use of mobile phone is tremendously increasing especially in developing countries, but not without a concern. The greater concern among the public is principally over the proximity of mobile base stations (MBS) to residential areas rather than the use of handsets. In this paper, we present an assessment of Radio-Frequency (RF) radiation exposure level measurements and analysis of radiation power density (in W/sq m) from mobile base stations relative to radial distance (in ...

  16. An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

    Directory of Open Access Journals (Sweden)

    Vida Zaroushani

    2015-06-01

    Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

  17. Multiscale Model Selection for High-Frequency Financial Data of a Large Tick Stock by Means of the Jensen–Shannon Metric

    Directory of Open Access Journals (Sweden)

    Gianbiagio Curato

    2014-01-01

    Full Text Available Modeling financial time series at different time scales is still an open challenge. The choice of a suitable indicator quantifying the distance between the model and the data is therefore of fundamental importance for selecting models. In this paper, we propose a multiscale model selection method based on the Jensen–Shannon distance in order to select the model that is able to better reproduce the distribution of price changes at different time scales. Specifically, we consider the problem of modeling the ultra high frequency dynamics of an asset with a large tick-to-price ratio. We study the price process at different time scales and compute the Jensen–Shannon distance between the original dataset and different models, showing that the coupling between spread and returns is important to model return distribution at different time scales of observation, ranging from the scale of single transactions to the daily time scale.

  18. Positive selection of deleterious alleles through interaction with a sex-ratio suppressor gene in African Buffalo: a plausible new mechanism for a high frequency anomaly.

    Directory of Open Access Journals (Sweden)

    Pim van Hooft

    Full Text Available Although generally rare, deleterious alleles can become common through genetic drift, hitchhiking or reductions in selective constraints. Here we present a possible new mechanism that explains the attainment of high frequencies of deleterious alleles in the African buffalo (Syncerus caffer population of Kruger National Park, through positive selection of these alleles that is ultimately driven by a sex-ratio suppressor. We have previously shown that one in four Kruger buffalo has a Y-chromosome profile that, despite being associated with low body condition, appears to impart a relative reproductive advantage, and which is stably maintained through a sex-ratio suppressor. Apparently, this sex-ratio suppressor prevents fertility reduction that generally accompanies sex-ratio distortion. We hypothesize that this body-condition-associated reproductive advantage increases the fitness of alleles that negatively affect male body condition, causing genome-wide positive selection of these alleles. To investigate this we genotyped 459 buffalo using 17 autosomal microsatellites. By correlating heterozygosity with body condition (heterozygosity-fitness correlations, we found that most microsatellites were associated with one of two gene types: one with elevated frequencies of deleterious alleles that have a negative effect on body condition, irrespective of sex; the other with elevated frequencies of sexually antagonistic alleles that are negative for male body condition but positive for female body condition. Positive selection and a direct association with a Y-chromosomal sex-ratio suppressor are indicated, respectively, by allele clines and by relatively high numbers of homozygous deleterious alleles among sex-ratio suppressor carriers. This study, which employs novel statistical techniques to analyse heterozygosity-fitness correlations, is the first to demonstrate the abundance of sexually-antagonistic genes in a natural mammal population. It also has

  19. Three-dimensional primate molar enamel thickness.

    Science.gov (United States)

    Olejniczak, Anthony J; Tafforeau, Paul; Feeney, Robin N M; Martin, Lawrence B

    2008-02-01

    Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of relative enamel thicknesses, and cercopithecoids have relatively thicker enamel than ceboids, which in turn have relatively thicker enamel than strepsirrhine primates, on average. Past studies performed using 2D sections appear to have accurately diagnosed the 3D relative enamel thickness condition in great apes and humans: Gorilla has the relatively thinnest enamel, Pan has relatively thinner enamel than Pongo, and Homo has the relatively thickest enamel. Although the data set presented here has some taxonomic gaps, it may serve as a useful reference for researchers investigating enamel thickness in fossil taxa and studies of primate gnathic biology.

  20. Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?

    Science.gov (United States)

    Kesharwani, Manoj K; Brauer, Brina; Martin, Jan M L

    2015-03-05

    We have obtained uniform frequency scaling factors λ(harm) (for harmonic frequencies), λ(fund) (for fundamentals), and λ(ZPVE) (for zero-point vibrational energies (ZPVEs)) for the Weigend-Ahlrichs and other selected basis sets for MP2, SCS-MP2, and a variety of DFT functionals including double hybrids. For selected levels of theory, we have also obtained scaling factors for true anharmonic fundamentals and ZPVEs obtained from quartic force fields. For harmonic frequencies, the double hybrids B2PLYP, B2GP-PLYP, and DSD-PBEP86 clearly yield the best performance at RMSD = 10-12 cm(-1) for def2-TZVP and larger basis sets, compared to 5 cm(-1) at the CCSD(T) basis set limit. For ZPVEs, again, the double hybrids are the best performers, reaching root-mean-square deviations (RMSDs) as low as 0.05 kcal/mol, but even mainstream functionals like B3LYP can get down to 0.10 kcal/mol. Explicitly anharmonic ZPVEs only are marginally more accurate. For fundamentals, however, simple uniform scaling is clearly inadequate.

  1. Fat suppression failure artifacts at the susceptibility interface on frequency selective fat suppression MR imaging in the head and neck

    International Nuclear Information System (INIS)

    Anzai, Yoshimi; Minoshima, Satoshi; Uno, Kimiichi; Arimizu, Noboru; Lufkin, R.B.; Ishihara, Makiko; Yui, Nobuharu.

    1994-01-01

    Fat suppression MR imaging is a valuable technique mainly used for the orbit, head and neck, and spine, where the high signal from fat can often obscure adjacent pathology. Fat suppression failure artifact manifested as a high signal area without geographic disortion. The purpose of this study was to investigate the frequency and common location of these artifacts in clinical MR imaging and to caution against their misinterpretation. Fat suppression MR imaging of the head and neck was performed in 30 consecutive patients. The artifact was found in the orbital floor (57%), the skull base (10%), and subcutaneous fat (10%), where the air-fat interface is parallel to the static magnetic field direction. The fat signal in the air-fat interface perpendicular to the static magnetic field was well suppressed. This artifact was independent of the duration of TE, frequency/phase encoding direction, and the strength of gradient amplitude, and appeared to be related to the amount of surrounding air. This may simulate pathology if fat suppression is only performed following Gd-DTPA administration. The radiologist should be aware of the presence of artifact by considering the geographic relation to the static magnetic field. (author)

  2. Energy consumption and economic growth for selected OECD countries: Further evidence from the Granger causality test in the frequency domain

    International Nuclear Information System (INIS)

    Bozoklu, Seref; Yilanci, Veli

    2013-01-01

    This paper aims to reexamine the causal relationship between energy consumption and economic growth for 20 OECD countries. To that end, we employ a Granger causality test in the frequency domain which allows us to distinguish short (temporary) and long-run (permanent) causality. The empirical results could be summarized as following. First, in terms of causality running from GDP to energy consumption, there is a temporary relationship for Australia, Austria, Canada, Italy, Japan, Mexico, the Netherlands, Portugal, the UK, the USA, and a permanent relationship for Austria, Belgium, Denmark, Germany, Italy, Japan, the Netherlands, Norway, and the USA. Second, in terms of causality running from energy consumption to GDP, there is a temporary relationship for Austria, Denmark, Italy, the Netherlands, Norway and Portugal, and a permanent relationship for Belgium, Finland, Greece, Italy, Japan, and Portugal. The main implication of our finding is that the energy policies should take into consideration not only the causality direction between economic growth and energy consumption but also whether it is temporal or permanent and furthermore authorities must design policy actions accordingly. - Highlights: • This study reexamines the causal relationship between energy consumption and economic growth. • We employ frequency causality analysis to determine temporary and permanent causality. • The results provide evidence of both temporary and permanent causality relationships for countries examined. • Energy policies should consider whether the causality is temporal or permanent

  3. Lead Thickness Measurements

    International Nuclear Information System (INIS)

    Rucinski, R.

    1998-01-01

    The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in 3 , an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.

  4. Site Selection Strategy of Single-Frequency Tuned R-APF for Background Harmonic Voltage Damping in Power Systems

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Zeng, Jian; Chen, Zhe

    2013-01-01

    , and analyze the harmonic voltage propagation caused by the background harmonic voltage in power systems. Then, a new strategy is proposed for the site selection of resistive active power filter to damp the background harmonic voltage in power systems. Experiments have been performed to verify the theoretical......Series resonance between capacitance and line inductance may magnify background harmonic voltage and worsen the harmonic voltage distortion in power systems. To solve this problem, in this paper, the transmission line theory is used to set up the distributed parameter model of power system feeders...

  5. Estimation of soft sediment thickness in Kuala Lumpur based on microtremor observation data

    Science.gov (United States)

    Chiew, Chang Chyau; Cheah, Yi Ben; Tan, Chin Guan; Lau, Tze Liang

    2017-10-01

    Seismic site effect is one of the major concerns in earthquake engineering. Soft ground tends to amplify the seismic wave in surficial geological layers. The determination of soft ground thickness on the surface layers of the earth is an important input for seismic hazard assessment. This paper presents an easy and convenient approach to estimate the soft sediment thickness at the site using microtremor observation technique. A total number of 133 survey points were conducted in selected sites around Kuala Lumpur area using a microtremor measuring instrument, but only 103 survey points contributed to the seismic microzonation and sediment thickness plots. The bedrock of Kuala Lumpur area is formed by Kenny Hill Formation, limestone, granite, and the Hawthornden Schist; however, the thickness of surface soft ground formed by alluvial deposits, mine tailings, and residual soils remains unknown. Hence, the predominant frequency of the ground in each site was determined based on Nakamura method. A total number of 14 sites with known depth to bedrock from the supply of geotechnical reports in the study area were determined. An empirical correlation was developed to relate the ground predominant frequency and soft ground thickness. This correlation may contribute to local soil underlying the subsurface of Kuala Lumpur area. The finding provides an important relationship for engineers to estimate the soft ground thickness in Kuala Lumpur area based on the dynamic characteristics of the ground measured from microtremor observation.

  6. The allele-frequency spectrum in a decoupled Moran model with mutation, drift, and directional selection, assuming small mutation rates.

    Science.gov (United States)

    Vogl, Claus; Clemente, Florian

    2012-05-01

    We analyze a decoupled Moran model with haploid population size N, a biallelic locus under mutation and drift with scaled forward and backward mutation rates θ(1)=μ(1)N and θ(0)=μ(0)N, and directional selection with scaled strength γ=sN. With small scaled mutation rates θ(0) and θ(1), which is appropriate for single nucleotide polymorphism data in highly recombining regions, we derive a simple approximate equilibrium distribution for polymorphic alleles with a constant of proportionality. We also put forth an even simpler model, where all mutations originate from monomorphic states. Using this model we derive the sojourn times, conditional on the ancestral and fixed allele, and under equilibrium the distributions of fixed and polymorphic alleles and fixation rates. Furthermore, we also derive the distribution of small samples in the diffusion limit and provide convenient recurrence relations for calculating this distribution. This enables us to give formulas analogous to the Ewens-Watterson estimator of θ for biased mutation rates and selection. We apply this theory to a polymorphism dataset of fourfold degenerate sites in Drosophila melanogaster. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Low-flow frequency and flow-duration characteristics of selected streams in Alabama through March 2014

    Science.gov (United States)

    Feaster, Toby D.; Lee, Kathyrn G.

    2017-08-28

    Low-flow statistics are needed by water-resource engineers, planners, and managers to protect and manage the water resources of Alabama. The accuracy of these statistics is influenced by such factors as length of record and specific hydrologic conditions measured in those records. As such, it is generally recommended that flow statistics be updated about every 10 years to provide improved and representative low-flow characteristics. The previous investigation of low-flow characteristics for Alabama included data through September 1990. Since that time, Alabama has experienced several historic droughts highlighting the need to update the low-flow characteristics at U.S. Geological Survey streamgaging stations. Consequently, this investigation was undertaken in cooperation with a number of State and local agencies to update low-flow frequency and flow-duration statistics at 210 continuous-record streamgaging stations in Alabama and 67 stations from basins that are shared with surrounding States. The flow characteristics were computed on the basis of available data through March 2014.

  8. WE-DE-206-03: MRI Image Formation - Slice Selection, Phase Encoding, Frequency Encoding, K-Space, SNR

    International Nuclear Information System (INIS)

    Lin, C.

    2016-01-01

    Magnetic resonance imaging (MRI) has become an essential part of clinical imaging due to its ability to render high soft tissue contrast. Instead of ionizing radiation, MRI use strong magnetic field, radio frequency waves and field gradients to create diagnostic useful images. It can be used to image the anatomy and also functional and physiological activities within the human body. Knowledge of the basic physical principles underlying MRI acquisition is vitally important to successful image production and proper image interpretation. This lecture will give an overview of the spin physics, imaging principle of MRI, the hardware of the MRI scanner, and various pulse sequences and their applications. It aims to provide a conceptual foundation to understand the image formation process of a clinical MRI scanner. Learning Objectives: Understand the origin of the MR signal and contrast from the spin physics level. Understand the main hardware components of a MRI scanner and their purposes Understand steps for MR image formation including spatial encoding and image reconstruction Understand the main kinds of MR pulse sequences and their characteristics.

  9. WE-DE-206-03: MRI Image Formation - Slice Selection, Phase Encoding, Frequency Encoding, K-Space, SNR

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C. [Indiana University School of Medicine (United States)

    2016-06-15

    Magnetic resonance imaging (MRI) has become an essential part of clinical imaging due to its ability to render high soft tissue contrast. Instead of ionizing radiation, MRI use strong magnetic field, radio frequency waves and field gradients to create diagnostic useful images. It can be used to image the anatomy and also functional and physiological activities within the human body. Knowledge of the basic physical principles underlying MRI acquisition is vitally important to successful image production and proper image interpretation. This lecture will give an overview of the spin physics, imaging principle of MRI, the hardware of the MRI scanner, and various pulse sequences and their applications. It aims to provide a conceptual foundation to understand the image formation process of a clinical MRI scanner. Learning Objectives: Understand the origin of the MR signal and contrast from the spin physics level. Understand the main hardware components of a MRI scanner and their purposes Understand steps for MR image formation including spatial encoding and image reconstruction Understand the main kinds of MR pulse sequences and their characteristics.

  10. Education and "Thick" Epistemology

    Science.gov (United States)

    Kotzee, Ben

    2011-01-01

    In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…

  11. Thick film hydrogen sensor

    Science.gov (United States)

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  12. Stand structure, composition and illegal logging in selectively logged production forests of Myanmar: Comparison of two compartments subject to different cutting frequency

    Directory of Open Access Journals (Sweden)

    Tual Cin Khai

    2016-07-01

    Full Text Available Appropriate cutting cycles and annual allowable cuts are crucial to ensure sustainability of tropical selective logging, but there have been limited field data to verify long-term effects of different cutting cycles. This study reveals some evidence of forest degradation in selectively logged production forests of Myanmar, which are subject to inappropriate cutting frequency. We compared stand structure, commercial species composition, and incidence of illegal logging between two compartments with low (LCF; 1 time and high (HCF; 5 times cutting frequency over a recent 18 years. Prior to the latest cutting, LCF had 176 trees ha−1 with an inverted-J shape distribution of diameter at breast height (DBH, including a substantial amount of teak (Tectona grandis and other commercially important species in each DBH class. HCF prior to the latest cut had only 41 trees ha−1 without many commercially important species. At HCF, nearly half the standing trees of various species and size were illegally cut following legal operations; this was for charcoal making in nearby kilns. At LCF, two species, teak and Xylia xylocarpa, were cut illegally and sawn for timber on the spot. More extensive and systematic surveys are needed to generalize the findings of forest degradation and illegal logging. However, our study calls for urgent reconsideration of logging practices with high cutting frequency, which can greatly degrade forests with accompanying illegal logging, and for rehabilitating strongly degraded, bamboo-dominated forests. To reduce illegal logging, it would be important to pay more attention on a MSS regulation stating that logging roads should be destroyed after logging operations.

  13. Automatic Feature Selection and Weighting for the Formation of Homogeneous Groups for Regional Intensity-Duration-Frequency (IDF) Curve Estimation

    Science.gov (United States)

    Yang, Z.; Burn, D. H.

    2017-12-01

    Extreme rainfall events can have devastating impacts on society. To quantify the associated risk, the IDF curve has been used to provide the essential rainfall-related information for urban planning. However, the recent changes in the rainfall climatology caused by climate change and urbanization have made the estimates provided by the traditional regional IDF approach increasingly inaccurate. This inaccuracy is mainly caused by two problems: 1) The ineffective choice of similarity indicators for the formation of a homogeneous group at different regions; and 2) An inadequate number of stations in the pooling group that does not adequately reflect the optimal balance between group size and group homogeneity or achieve the lowest uncertainty in the rainfall quantiles estimates. For the first issue, to consider the temporal difference among different meteorological and topographic indicators, a three-layer design is proposed based on three stages in the extreme rainfall formation: cloud formation, rainfall generation and change of rainfall intensity above urban surface. During the process, the impacts from climate change and urbanization are considered through the inclusion of potential relevant features at each layer. Then to consider spatial difference of similarity indicators for the homogeneous group formation at various regions, an automatic feature selection and weighting algorithm, specifically the hybrid searching algorithm of Tabu search, Lagrange Multiplier and Fuzzy C-means Clustering, is used to select the optimal combination of features for the potential optimal homogenous groups formation at a specific region. For the second issue, to compare the uncertainty of rainfall quantile estimates among potential groups, the two sample Kolmogorov-Smirnov test-based sample ranking process is used. During the process, linear programming is used to rank these groups based on the confidence intervals of the quantile estimates. The proposed methodology fills the gap

  14. Performance Analysis of the IEEE 802.11A WLAN Standard Optimum and Sub-Optimum Receiver in Frequency-Selective, Slowly Fading Nakagami Channels with AWGN and Pulsed Noise Jamming

    National Research Council Canada - National Science Library

    Kalogrias, Christos

    2004-01-01

    ... 802.11a wireless local area network (WLAN) standard receiver when the signal is transmitted over a frequency selective, slow fading Nakagami channel in a worst case, pulse-noise jamming environment...

  15. MR imaging of osteonecrosis using frequency selective chemical shift sequences; Neue Aspekte in der MR-Diagnostik der Osteonekrose: Selektive Fett/Wasser-Bildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Duda, S H [Abt. fuer Radiologische Diagnostik, Tuebingen Univ. (Germany); Laniado, M [Abt. fuer Radiologische Diagnostik, Tuebingen Univ. (Germany); Schick, F [Inst. fuer Physik, Tuebingen Univ. (Germany)

    1994-12-31

    The MR appearance of osteonecrosis was assessed on selective fat- and water images to further evaluate the nature of double-line sign. Conventional T1- and T2-weighted SE and frequency selective chemical shift images of eight patients with avascular necrosis of the femoral head and three patients with bone infarcts were retrospectively reviewed. Eight of 11 patients showed a double-line sign on T2-weighted SE images. In these cases, correlation with selective water images revealed that a chemical shift artifact contributed to appearance and location of the hyperintense line. The authors conclude that chemical shift imaging improves our understanding of the nature of the double-line sign. (orig.) [Deutsch] Das MR-tomographische Erscheinungsbild der Osteonekrose auf selektiven Fett- und Wasserbildern wurde analysiert, um das in der Literatur beschriebene Doppellinienzeichen naeher zu untersuchen. Hierfuer wurden sowohl die herkoemmlichen T1- und T2-gewichteten Spin-Echo-Sequenzen herangezogen, als auch frequenzselektive Bilder, die aufgrund chemischer Verschiebung gewonnen wurden (1,5 T). Es wurden die Untersuchungen von acht Patienten mit avaskulaerer Hueftkopfnekrose und von drei Patienten mit Knocheninfarkten retrospektiv ausgewertet. Acht von 11 Patienten zeigten ein Doppellinienzeichen auf den T2-gewichteten Bildern. Die Korrelation mit den selektiven Wasserbildern ergab, dass durch chemische Verschiebung bedingte Artefakte das Erscheinungsbild und den Ort der hyperintensen Linie beeinflussten. Die Bildgebung mit Hilfe der chemischen Verschiebung verbessert unser Verstaendnis der MRT-Charakteristika der Osteonekrose. (orig.)

  16. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  17. Regional regression equations for the estimation of selected monthly low-flow duration and frequency statistics at ungaged sites on streams in New Jersey

    Science.gov (United States)

    Watson, Kara M.; McHugh, Amy R.

    2014-01-01

    Regional regression equations were developed for estimating monthly flow-duration and monthly low-flow frequency statistics for ungaged streams in Coastal Plain and non-coastal regions of New Jersey for baseline and current land- and water-use conditions. The equations were developed to estimate 87 different streamflow statistics, which include the monthly 99-, 90-, 85-, 75-, 50-, and 25-percentile flow-durations of the minimum 1-day daily flow; the August–September 99-, 90-, and 75-percentile minimum 1-day daily flow; and the monthly 7-day, 10-year (M7D10Y) low-flow frequency. These 87 streamflow statistics were computed for 41 continuous-record streamflow-gaging stations (streamgages) with 20 or more years of record and 167 low-flow partial-record stations in New Jersey with 10 or more streamflow measurements. The regression analyses used to develop equations to estimate selected streamflow statistics were performed by testing the relation between flow-duration statistics and low-flow frequency statistics for 32 basin characteristics (physical characteristics, land use, surficial geology, and climate) at the 41 streamgages and 167 low-flow partial-record stations. The regression analyses determined drainage area, soil permeability, average April precipitation, average June precipitation, and percent storage (water bodies and wetlands) were the significant explanatory variables for estimating the selected flow-duration and low-flow frequency statistics. Streamflow estimates were computed for two land- and water-use conditions in New Jersey—land- and water-use during the baseline period of record (defined as the years a streamgage had little to no change in development and water use) and current land- and water-use conditions (1989–2008)—for each selected station using data collected through water year 2008. The baseline period of record is representative of a period when the basin was unaffected by change in development. The current period is

  18. Iterative MMSE Detection for MIMO/BLAST DS-CDMA Systems in Frequency Selective Fading Channels - Achieving High Performance in Fully Loaded Systems

    Science.gov (United States)

    Silva, João Carlos; Souto, Nuno; Cercas, Francisco; Dinis, Rui

    A MMSE (Minimum Mean Square Error) DS-CDMA (Direct Sequence-Code Division Multiple Access) receiver coupled with a low-complexity iterative interference suppression algorithm was devised for a MIMO/BLAST (Multiple Input, Multiple Output / Bell Laboratories Layered Space Time) system in order to improve system performance, considering frequency selective fading channels. The scheme is compared against the simple MMSE receiver, for both QPSK and 16QAM modulations, under SISO (Single Input, Single Output) and MIMO systems, the latter with 2Tx by 2Rx and 4Tx by 4Rx (MIMO order 2 and 4 respectively) antennas. To assess its performance in an existing system, the uncoded UMTS HSDPA (High Speed Downlink Packet Access) standard was considered.

  19. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  20. An algorithm developed in Matlab for the automatic selection of cut-off frequencies, in the correction of strong motion data

    Science.gov (United States)

    Sakkas, Georgios; Sakellariou, Nikolaos

    2018-05-01

    Strong motion recordings are the key in many earthquake engineering applications and are also fundamental for seismic design. The present study focuses on the automated correction of accelerograms, analog and digital. The main feature of the proposed algorithm is the automatic selection for the cut-off frequencies based on a minimum spectral value in a predefined frequency bandwidth, instead of the typical signal-to-noise approach. The algorithm follows the basic steps of the correction procedure (instrument correction, baseline correction and appropriate filtering). Besides the corrected time histories, Peak Ground Acceleration, Peak Ground Velocity, Peak Ground Displacement values and the corrected Fourier Spectra are also calculated as well as the response spectra. The algorithm is written in Matlab environment, is fast enough and can be used for batch processing or in real-time applications. In addition, the possibility to also perform a signal-to-noise ratio is added as well as to perform causal or acausal filtering. The algorithm has been tested in six significant earthquakes (Kozani-Grevena 1995, Aigio 1995, Athens 1999, Lefkada 2003 and Kefalonia 2014) of the Greek territory with analog and digital accelerograms.

  1. Fat suppression strategies in MR imaging of breast cancer at 3.0 T. Comparison of the two-point dixon technique and the frequency selective inversion method

    International Nuclear Information System (INIS)

    Kaneko Mikami, Wakako; Kazama, Toshiki; Sato, Hirotaka

    2013-01-01

    The purpose of this study was to compare two fat suppression methods in contrast-enhanced MR imaging of breast cancer at 3.0 T: the two-point Dixon method and the frequency selective inversion method. Forty female patients with breast cancer underwent contrast-enhanced three-dimensional T1-weighted MR imaging at 3.0 T. Both the two-point Dixon method and the frequency selective inversion method were applied. Quantitative analyses of the residual fat signal-to-noise ratio and the contrast noise ratio (CNR) of lesion-to-breast parenchyma, lesion-to-fat, and parenchyma-to-fat were performed. Qualitative analyses of the uniformity of fat suppression, image contrast, and the visibility of breast lesions and axillary metastatic adenopathy were performed. The signal-to-noise ratio was significantly lower in the two-point Dixon method (P<0.001). All CNR values were significantly higher in the two-point Dixon method (P<0.001 and P=0.001, respectively). According to qualitative analysis, both the uniformity of fat suppression and image contrast with the two-point Dixon method were significantly higher (P<0.001 and P=0.002, respectively). Visibility of breast lesions and metastatic adenopathy was significantly better in the two-point Dixon method (P<0.001 and P=0.03, respectively). The two-point Dixon method suppressed the fat signal more potently and improved contrast and visibility of the breast lesions and axillary adenopathy. (author)

  2. Thick-film analysis: literature search and bibliography

    International Nuclear Information System (INIS)

    Gehman, R.W.

    1981-09-01

    A literature search was conducted to support development of in-house diagnostic testing of thick film materials for hybrid microcircuits. A background literature review covered thick film formulation, processing, structure, and performance. Important material properties and tests were identified and several test procedures were obtained. Several tests were selected for thick film diagnosis at Bendix Kansas City. 126 references

  3. AEP's selection of GE Energy's variable frequency transformer (VFT) for their grid interconnection project between the United States and Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Spurlock, M.; O' Keefe, R. [American Electric Power, Gahanna, OH (United States); Kidd, D. [American Electric Power, Tulsa, OK (United States); Larsen, E. [GE Energy, Schenectady, NY (United States); Roedel, J. [GE Energy, Denver, CO (United States); Bodo, R. [GE Energy, Carrolton, TX (United States); Marken, P. [GE Energy, Columbia City, IN (United States)

    2006-07-01

    Variable frequency transformers (VFTs) are controllable, bi-directional transmission devices capable of allowing power transfer between asynchronous networks. The VFT uses a rotary transformer with 3-phase windings on both the rotor and the stator. A motor and drive system is also used to manipulate the rotational position of the rotor in order to control the magnitude and direction of the power flow. The VFT was recently selected by American Electric Power (AEP) for its new asynchronous transmission link between the United States and Mexico. This paper provided details of the feasibility studies conducted to select the technology. Three categories of asynchronous interconnection devices were evaluated: (1) a VFT; (2) a voltage source converter; and (3) a conventional high voltage direct current (HVDC) back-to-back system. Stability performance system studies were conducted for all options. The overall reliability benefits of the options were reviewed, as well as their ability to meet steady-state system requirements. Dynamic models were used to conduct the comparative evaluation. Results of the feasibility study indicated that both the VFT and the voltage source converter performed better than the HVDC system. However, the VFT was more stable than the voltage source converter. 5 refs., 3 figs.

  4. Monitoring production target thickness

    International Nuclear Information System (INIS)

    Oothoudt, M.A.

    1993-01-01

    Pion and muon production targets at the Clinton P. Anderson Meson Physics Facility consist of rotating graphite wheels. The previous target thickness monitoring Procedure scanned the target across a reduced intensity beam to determine beam center. The fractional loss in current across the centered target gave a measure of target thickness. This procedure, however, required interruption of beam delivery to experiments and frequently indicated a different fractional loss than at normal beam currents. The new monitoring Procedure compares integrated ups and downs toroid current monitor readings. The current monitors are read once per minute and the integral of readings are logged once per eight-hour shift. Changes in the upstream to downstream fractional difference provide a nonintrusive continuous measurement of target thickness under nominal operational conditions. Target scans are now done only when new targets are installed or when unexplained changes in the current monitor data are observed

  5. Comparison of automatic procedures in the selection of peaks over threshold in flood frequency analysis: A Canadian case study in the context of climate change

    Science.gov (United States)

    Durocher, M.; Mostofi Zadeh, S.; Burn, D. H.; Ashkar, F.

    2017-12-01

    Floods are one of the most costly hazards and frequency analysis of river discharges is an important part of the tools at our disposal to evaluate their inherent risks and to provide an adequate response. In comparison to the common examination of annual streamflow maximums, peaks over threshold (POT) is an interesting alternative that makes better use of the available information by including more than one flood event per year (on average). However, a major challenge is the selection of a satisfactory threshold above which peaks are assumed to respect certain conditions necessary for an adequate estimation of the risk. Additionally, studies have shown that POT is also a valuable approach to investigate the evolution of flood regimes in the context of climate change. Recently, automatic procedures for the selection of the threshold were suggested to guide that important choice, which otherwise rely on graphical tools and expert judgment. Furthermore, having an automatic procedure that is objective allows for quickly repeating the analysis on a large number of samples, which is useful in the context of large databases or for uncertainty analysis based on a resampling approach. This study investigates the impact of considering such procedures in a case study including many sites across Canada. A simulation study is conducted to evaluate the bias and predictive power of the automatic procedures in similar conditions as well as investigating the power of derived nonstationarity tests. The results obtained are also evaluated in the light of expert judgments established in a previous study. Ultimately, this study provides a thorough examination of the considerations that need to be addressed when conducting POT analysis using automatic threshold selection.

  6. Coating thickness measurement

    International Nuclear Information System (INIS)

    1976-12-01

    The standard specifies measurements of the coating thickness, which make use of beta backscattering and/or x-ray fluorescence. For commonly used combinations of coating material and base material the appropriate measuring ranges and radionuclides to be used are given for continuous as well as for discontinuous measurements

  7. Portion Sizes from 24-Hour Dietary Recalls Differed by Sex among Those Who Selected the Same Portion Size Category on a Food Frequency Questionnaire.

    Science.gov (United States)

    Kang, Minji; Park, Song-Yi; Boushey, Carol J; Wilkens, Lynne R; Monroe, Kristine R; Le Marchand, Loïc; Kolonel, Laurence N; Murphy, Suzanne P; Paik, Hee-Young

    2018-05-08

    Accounting for sex differences in food portions may improve dietary measurement; however, this factor has not been well examined. The aim of this study was to examine sex differences in reported food portions from 24-hour dietary recalls (24HDRs) among those who selected the same portion size category on a quantitative food frequency questionnaire (QFFQ). This study was conducted with a cross-sectional design. Participants (n=319) were members of the Hawaii-Los Angeles Multiethnic Cohort who completed three 24HDRs and a QFFQ in a calibration study conducted in 2010 and 2011. Portions of individual foods reported from 24HDRs served as the outcome measures. Mean food portions from 24HDRs were compared between men and women who reported the same portion size on the QFFQ, after adjustment for race/ethnicity using a linear regression model. Actual amount and the assigned amount of the selected portion size in the QFFQ were compared using one-sample t test for men and women separately. Of 163 food items with portion size options listed in the QFFQ, 32 were reported in 24HDRs by ≥20 men and ≥20 women who selected the same portion size in the QFFQ. Although they chose the same portion size on the QFFQ, mean intake amounts from 24HDRs were significantly higher for men than for women for "beef/lamb/veal," "white rice," "brown/wild rice," "lettuce/tossed salad," "eggs cooked/raw," "whole wheat/rye bread," "buns/rolls," and "mayonnaise in sandwiches." For men, mean portions of 14 items from the 24HDRs were significantly different from the assigned amounts for QFFQ items (seven higher and seven lower), whereas for women, mean portions of 14 items were significantly lower from the assigned amounts (with five significantly higher). These sex differences in reported 24HDR food portions-even among participants who selected the same portion size on the QFFQ-suggest that the use of methods that account for differences in the portions consumed by men and women when QFFQs are

  8. [Influence of elevated homocystein level and selected lipid parameters in kidney transplant patients on the progression of atherosclerotic changes assessed by intima-media thickness index (CCA-IMT)].

    Science.gov (United States)

    Janda, Katarzyna; Aksamit, Dariusz; Drozdz, Maciej; Krzanowski, Marcin; Ignacak, Ewa; Kowalczyk-Michałek, Martyna; Tabor-Ciepiela, Barbara; Sułowicz, Władysław

    2012-01-01

    The aim of the study was to evaluate the influence of elevated homocystein (Hcy) level and selected lipid parameters on the progression of atherosclerotic changes in patients after kidney transplantation (KTx). The study included 51 pts (17 F, 34 M) aged 15-62 years (median 38.1) after cadaver KTx. The mean observation period equaled 21.2 months (6-24 months); while total observation period was 90 patients/ years. Hcy levels was measured using HPLC, Lp(a) and Apo-B levels using the nephelometric method and total cholesterol with its' HDL and LDL fractions, triglycerides and creatinine based on the Hitachi 917 analyzer. Patients' blood was drawn before renal transplantation and 3, 6, 9, 12, 15, 18, 21 and 24 months after KTx. Common carotid artery intima media thickness (CCA-IMT) was evaluated by ultrasound on 14 days, 12 and 24 months after KTx. CCA-IMT correlated significantly with Hcy levels after 12 months (R=0.53; p=0.0009) and 24 months (R=0.38; p=0.0356) after KTx. Significant differences were found 12 and 24 months after KTx in CCA-IMT between patients with normal (15 micromol/ l) mean Hcy concentrations: p=0.0035 and p= 0.015, respectively. Analyzing changes in CCA-IMT, significant differences were noted when comparing the CCA-IMT increment after 12 and 24 months post KTx in patients with normal (15 micromol/l) homocystein concentrations: p=0.049 and p=0.0039, respectively. Increment of CCA-IMT 12 months after KTx, significantly correlated with mean total cholesterol level (R=0.35; p=0.0333), whereas 24 months after procedure correlated significantly with 0.0315). Hcy level is an independent risk factor for atherosclerosis development in patients after KTx. Elevated Hcy level as well as increased cholesterol and Lp(a) levels enhance the progression of atherosclerotic changes evaluated by CCA-IMT in KTx patients.

  9. Novel 3D ultrasound image-based biomarkers based on a feature selection from a 2D standardized vessel wall thickness map: a tool for sensitive assessment of therapies for carotid atherosclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Bernard; Bing, Li; Chow, Tommy W S, E-mail: bcychiu@cityu.edu.hk, E-mail: bingli5@student.cityu.edu.hk, E-mail: eetchow@cityu.edu.hk [Department of Electronic Engineering, City University of Hong Kong (Hong Kong)

    2013-09-07

    With the advent of new therapies and management strategies for carotid atherosclerosis, there is a parallel need for measurement tools or biomarkers to evaluate the efficacy of these new strategies. 3D ultrasound has been shown to provide reproducible measurements of plaque area/volume and vessel wall volume. However, since carotid atherosclerosis is a focal disease that predominantly occurs at bifurcations, biomarkers based on local plaque change may be more sensitive than global volumetric measurements in demonstrating efficacy of new therapies. The ultimate goal of this paper is to develop a biomarker that is based on the local distribution of vessel-wall-plus-plaque thickness change (VWT-Change) that has occurred during the course of a clinical study. To allow comparison between different treatment groups, the VWT-Change distribution of each subject must first be mapped to a standardized domain. In this study, we developed a technique to map the 3D VWT-Change distribution to a 2D standardized template. We then applied a feature selection technique to identify regions on the 2D standardized map on which subjects in different treatment groups exhibit greater difference in VWT-Change. The proposed algorithm was applied to analyse the VWT-Change of 20 subjects in a placebo-controlled study of the effect of atorvastatin (Lipitor). The average VWT-Change for each subject was computed (i) over all points in the 2D map and (ii) over feature points only. For the average computed over all points, 97 subjects per group would be required to detect an effect size of 25% that of atorvastatin in a six-month study. The sample size is reduced to 25 subjects if the average were computed over feature points only. The introduction of this sensitive quantification technique for carotid atherosclerosis progression/regression would allow many proof-of-principle studies to be performed before a more costly and longer study involving a larger population is held to confirm the treatment

  10. Novel 3D ultrasound image-based biomarkers based on a feature selection from a 2D standardized vessel wall thickness map: a tool for sensitive assessment of therapies for carotid atherosclerosis

    International Nuclear Information System (INIS)

    Chiu, Bernard; Li Bing; Chow, Tommy W S

    2013-01-01

    With the advent of new therapies and management strategies for carotid atherosclerosis, there is a parallel need for measurement tools or biomarkers to evaluate the efficacy of these new strategies. 3D ultrasound has been shown to provide reproducible measurements of plaque area/volume and vessel wall volume. However, since carotid atherosclerosis is a focal disease that predominantly occurs at bifurcations, biomarkers based on local plaque change may be more sensitive than global volumetric measurements in demonstrating efficacy of new therapies. The ultimate goal of this paper is to develop a biomarker that is based on the local distribution of vessel-wall-plus-plaque thickness change (VWT-Change) that has occurred during the course of a clinical study. To allow comparison between different treatment groups, the VWT-Change distribution of each subject must first be mapped to a standardized domain. In this study, we developed a technique to map the 3D VWT-Change distribution to a 2D standardized template. We then applied a feature selection technique to identify regions on the 2D standardized map on which subjects in different treatment groups exhibit greater difference in VWT-Change. The proposed algorithm was applied to analyse the VWT-Change of 20 subjects in a placebo-controlled study of the effect of atorvastatin (Lipitor). The average VWT-Change for each subject was computed (i) over all points in the 2D map and (ii) over feature points only. For the average computed over all points, 97 subjects per group would be required to detect an effect size of 25% that of atorvastatin in a six-month study. The sample size is reduced to 25 subjects if the average were computed over feature points only. The introduction of this sensitive quantification technique for carotid atherosclerosis progression/regression would allow many proof-of-principle studies to be performed before a more costly and longer study involving a larger population is held to confirm the treatment

  11. Terahertz Mapping of Microstructure and Thickness Variations

    Science.gov (United States)

    Roth, Donald J.; Seebo, Jeffrey P.; Winfree, William P.

    2010-01-01

    A noncontact method has been devised for mapping or imaging spatial variations in the thickness and microstructure of a layer of a dielectric material. The method involves (1) placement of the dielectric material on a metal substrate, (2) through-the-thickness pulse-echo measurements by use of electromagnetic waves in the terahertz frequency range with a raster scan in a plane parallel to the substrate surface that do not require coupling of any kind, and (3) appropriate processing of the digitized measurement data.

  12. Application of the Modified Vlasov Model to the Free Vibration Analysis of Thick Plates Resting on Elastic Foundations

    Directory of Open Access Journals (Sweden)

    Korhan Ozgan

    2009-01-01

    Full Text Available The Modified Vlasov Model is applied to the free vibration analysis of thick plates resting on elastic foundations. The effects of the subsoil depth, plate dimensions and their ratio, the value of the vertical deformation parameter within the subsoil on the frequency parameters of plates on elastic foundations are investigated. A four-noded, twelve degrees of freedom quadrilateral finite element (PBQ4 is used for plate bending analysis based on Mindlin plate theory which is effectively applied to the analysis of thin and thick plates when selective reduced integration technique is used. The first ten natural frequency parameters are presented in tabular and graphical forms to show the effects of the parameters considered in the study. It is concluded that the effect of the subsoil depth on the frequency parameters of the plates on elastic foundation is generally larger than that of the other parameters considered in the study.

  13. Performance of Reverse-Link Synchronous DS-CDMA System on a Frequency-Selective Multipath Fading Channel with Imperfect Power Control

    Directory of Open Access Journals (Sweden)

    Duk Kyung Kim

    2002-08-01

    Full Text Available We analyze the performance for reverse-link synchronous DS-CDMA system in a frequency-selective Rayleigh fading channel with an imperfect power control scheme. The performance degradation due to power control error (PCE, which is approximated by a log-normally distributed random variable, is estimated as a function of the standard deviation of the PCE. In addition, we investigate the impacts of the multipath intensity profile (MIP shape and the number of resolvable paths on the performance. Finally, the coded bit error performance is evaluated in order to estimate the system capacity. Comparing with the conventional CDMA system, we show an achievable gain of from 59% to 23% for reverse-link synchronous transmission technique (RLSTT in the presence of imperfect power control over asynchronous transmission for BER=10−6. As well, the effect of tradeoff between orthogonality and diversity can be seen according to the number of multipaths, and the tendency is kept even in the presence of PCE. We conclude that the capacity can be further improved via the RLSTT, because the DS-CDMA system is very sensitive to power control imperfections.

  14. New Concept of PLC Modems: Multi-Carrier System for Frequency Selective Slow-Fading Channels Based on Layered SCCC Turbocodes

    Directory of Open Access Journals (Sweden)

    J. Zavrtalek

    2015-09-01

    Full Text Available The article introduces a novel concept of a PLC modem as a complement to the existing G3 and PRIME standards for communications using medium- or high-voltage overhead or cable lines. The proposed concept is based on the fact that the levels of impulse noise and frequency selectivity are lower on high-voltage lines than on low-voltage ones. Also, the demands for “cost-effective” circuitry design are not so crucial as in the case of modems for low-voltage level. In contract to these positive conditions, however, there is the need to overcome much longer distances and to take into account low SNR on the receiving side. With respect to the listed reasons, our concept makes use of MCM, instead of OFDM. The assumption of low SNR is compensated through the use of an efficient channel coding based on a serially concatenated turbo code. In addition, MCM offers lower latency and PAPR compared to OFDM. Therefore, when using MCM, it is possible to excite the line with higher power. The proposed concept has been verified during experimental transmission of testing data over a real, 5 km long, 22kV overhead line.

  15. Coating thickness measuring device

    International Nuclear Information System (INIS)

    Joffe, B.B.; Sawyer, B.E.; Spongr, J.J.

    1984-01-01

    A device especially adapted for measuring the thickness of coatings on small, complexly-shaped parts, such as, for example, electronic connectors, electronic contacts, or the like. The device includes a source of beta radiation and a radiation detector whereby backscatter of the radiation from the coated part can be detected and the thickness of the coating ascertained. The radiation source and detector are positioned in overlying relationship to the coated part and a microscope is provided to accurately position the device with respect to the part. Means are provided to control the rate of descent of the radiation source and radiation detector from its suspended position to its operating position and the resulting impact it makes with the coated part to thereby promote uniformity of readings from operator to operator, and also to avoid excessive impact with the part, thereby improving accuracy of measurement and eliminating damage to the parts

  16. Thick brane solutions

    International Nuclear Information System (INIS)

    Dzhunushaliev, Vladimir; Minamitsuji, Masato; Folomeev, Vladimir

    2010-01-01

    This paper gives a comprehensive review on thick brane solutions and related topics. Such models have attracted much attention from many aspects since the birth of the brane world scenario. In many works, it has been usually assumed that a brane is an infinitely thin object; however, in more general situations, one can no longer assume this. It is also widely considered that more fundamental theories such as string theory would have a minimal length scale. Many multidimensional field theories coupled to gravitation have exact solutions of gravitating topological defects, which can represent our brane world. The inclusion of brane thickness can realize a variety of possible brane world models. Given our understanding, the known solutions can be classified into topologically non-trivial solutions and trivial ones. The former class contains solutions of a single scalar (domain walls), multi-scalar, gauge-Higgs (vortices), Weyl gravity and so on. As an example of the latter class, we consider solutions of two interacting scalar fields. Approaches to obtain cosmological equations in the thick brane world are reviewed. Solutions with spatially extended branes (S-branes) and those with an extra time-like direction are also discussed.

  17. Vibration of Elastic Functionally Graded Thick Rings

    Directory of Open Access Journals (Sweden)

    Guang-Hui Xu

    2017-01-01

    Full Text Available The free vibration behaviors of functionally graded rings were investigated theoretically. The material graded in the thickness direction according to the power law rule and the rings were assumed to be in plane stress and plane strain states. Based on the first-order shear deformation theory and the kinetic relation of von Kárman type, the frequency equation for free vibration of functionally graded ring was derived. The derived results were verified by those in literatures which reveals that the present theory can be appropriate to predict the free vibration characteristics for quite thick rings with the radius-to-thickness ratio from 60 down to 2.09. Comparison between the plane stress case and the plane strain case indicates a slight difference. Meanwhile, the effects of the structural dimensional parameters and the material inhomogeneous parameter are examined. It is interesting that the value of the logarithmic form of vibration frequency is inversely proportional to the logarithmic form of the radius-to-thickness ratio or the mean radius.

  18. Full reflector thickness and isolation thickness on neutron transport

    International Nuclear Information System (INIS)

    Sakai, Tomohiro; Naito, Yoshitaka; Komuro, Yuichi.

    1988-08-01

    A method to determine ''full reflector thickness'' and ''isolation thickness'', which is utilized for criticality safety evaluation on nuclear fuel facilities, was proposed in this paper. Firstly, a calculation was tryed to obtain the two kinds of thicknesses from the result of criticality calculations for a specific case. Then, two simple equations which calculates the two kinds of thicknesses were made from the relation between reflector (or isolator) thickness and k eff , and one-group diffusion theory. Finally, we proposed a new method to determine the thicknesses. From the method we proposed, ''full reflector thickness'' and ''isolation thickness'' can be obtain using the equations and migration length of the reflector (or isolator) and infinite and effective multiplication factor of the fuel. (author)

  19. Corrosion monitoring using high-frequency guided waves

    Science.gov (United States)

    Fromme, P.

    2016-04-01

    Corrosion can develop due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Generalized corrosion leading to wall thickness loss can cause the reduction of the strength and thus degradation of the structural integrity. The monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic wedge transducers with single sided access to the structure, guided wave modes were selectively generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted for wall thickness reduction due to milling of the steel structure. From the measured signal changes due to the wave mode interference the reduced wall thickness was monitored. Good agreement with theoretical predictions was achieved. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  20. Low Frequency Space Array

    International Nuclear Information System (INIS)

    Dennison, B.; Weiler, K.W.; Johnston, K.J.

    1987-01-01

    The Low Frequency Space Array (LFSA) is a conceptual mission to survey the entire sky and to image individual sources at frequencies between 1.5 and 26 MHz, a frequency range over which the earth's ionosphere transmits poorly or not at all. With high resolution, high sensitivity observations, a new window will be opened in the electromagnetic spectrum for astronomical investigation. Also, extending observations down to such low frequencies will bring astronomy to the fundamental limit below which the galaxy becomes optically thick due to free-free absorption. A number of major scientific goals can be pursued with such a mission, including mapping galactic emission and absorption, studies of individual source spectra in a frequency range where a number of important processes may play a role, high resolution imaging of extended sources, localization of the impulsive emission from Jupiter, and a search for coherent emission processes. 19 references

  1. Feasibility study of 2D thick-slice MR digital subtraction angiography

    International Nuclear Information System (INIS)

    Ishimori, Yoshiyuki; Takeuchi, Miho; Higashimura, Kyouji; Komuro, Hiroyuki

    2000-01-01

    Conditions required to perform contrast MR digital subtraction angiography using a two-dimensional thick-slice high-speed gradient echo were investigated. The conditions in the phantom experiment included: slice profile, flip angle, imaging matrix, fat suppression, duration of IR pulse and frequency selectivity, flip angle of IR pulse and inversion time. Based on the results of the experiment, 2D thick-slice MRDSA was performed in volunteers. Under TR/TE=5.3-9/1.3-1.8 ms conditions, the requirements were a slice thick enough to include the target region, a flip angle of 10 degrees, and a phase matrix of 96 or more. Fat suppression was required for adipose-tissue-rich regions, such as the abdomen. The optimal conditions for applying the IR preparation pulse of the IR prepped fast gradient recalled echo as spectrally selective inversion recovery appeared to be: duration of IR pulse =20 ms, flip angle =100 degrees, and inversion time =40 ms. The authors concluded that it was feasible to perform 2D thick-slice MRDSA with time resolution within 1 second. (K.H.)

  2. Substrate effects on terahertz metamaterial resonances for various metal thicknesses

    International Nuclear Information System (INIS)

    Park, S. J.; Ahn, Y. H.

    2014-01-01

    We demonstrate dielectric substrate effects on the resonance shift of terahertz metamaterials with various metal thicknesses by using finite-difference time-domain simulations. We found a small red shift in the metamaterial resonance with increasing metal thickness for the free-standing case. Conversely, when the metamaterial pattern was supported by a substrate with a high dielectric constant, the resonant frequency exhibited a large blue shift because the relative contribution of the substrate's refractive index to the resonant frequency decreased drastically as we increased the metal thickness. We determined the substrate's refractive index, 1.26, at which the metamaterial resonance was independent of the metal thickness. We extracted the effective refractive index as a function of the substrate's refractive index explicitly, which was noticeably different for different film thicknesses.

  3. Mapping sediment thickness of Islamabad city using empirical ...

    Indian Academy of Sciences (India)

    A number of studies in recent years have demonstrated that frequency and ... sediment thicknesses derived from empirical relations developed in this study with ... Location map of the study area, the bold light grey line shows the boundary of the Islamabad region. .... frequency disturbances (wind blowing, in case of near tall ...

  4. Radioactive thickness gauge (1962)

    International Nuclear Information System (INIS)

    Guizerix, J.

    1962-01-01

    The author describes a thickness gauge in which the scintillating crystal detector alternately 'sees' a radioactive source through the material which is to be measured and then a control source of the same material; the radiations are separated in time by an absorbing valve whose sections are alternately full and hollow. The currents corresponding to the two sources are separated beyond the photomultiplier tube by a detector synchronized with the rotation of the valve. The quotient of these two currents is then obtained with a standard recording potentiometer. It is found that the average value of the response which is in the form G = f(I 1 /I 2 ) is not affected by decay of the radioactive sources, and that it is little influenced by variations of high tension, temperature, or properties of the air in the source detector interval. The performance of the gauge is given. (author) [fr

  5. Thick-Big Descriptions

    DEFF Research Database (Denmark)

    Lai, Signe Sophus

    The paper discusses the rewards and challenges of employing commercial audience measurements data – gathered by media industries for profitmaking purposes – in ethnographic research on the Internet in everyday life. It questions claims to the objectivity of big data (Anderson 2008), the assumption...... communication systems, language and behavior appear as texts, outputs, and discourses (data to be ‘found’) – big data then documents things that in earlier research required interviews and observations (data to be ‘made’) (Jensen 2014). However, web-measurement enterprises build audiences according...... to a commercial logic (boyd & Crawford 2011) and is as such directed by motives that call for specific types of sellable user data and specific segmentation strategies. In combining big data and ‘thick descriptions’ (Geertz 1973) scholars need to question how ethnographic fieldwork might map the ‘data not seen...

  6. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    International Nuclear Information System (INIS)

    Kwon, Joonhyung; Kim, Joonhui; Jeong, Jong-Hwa; Lee, Euy-Kyu; Seok Kim, Yong; Kang, Chi Jung; Park, Sang-il

    2005-01-01

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10 -19 F/V

  7. Disentangling The Thick Concept Argument

    DEFF Research Database (Denmark)

    Blomberg, Olle

    2007-01-01

    Critics argue that non-cognitivism cannot adequately account for the existence and nature of some thick moral concepts. They use the existence of thick concepts as a lever in an argument against non-cognitivism, here called the Thick Concept Argument (TCA). While TCA is frequently invoked...

  8. Influence of slice thickness on the determination of left ventricular wall thickness and dimension by magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato and others

    1989-02-01

    Wall thickness of the ventricular septum and left ventricle, and left ventricular cavity dimension were determined on magnetic resonance (MR) images with slices 5 mm and 10 mm in thickness. Subjects were 3 healthy volunteers and 7 patients with hypertension (4), hypertrophic cardiomyopathy (one) or valvular heart disease (2). In visualizing the cardiac structures such as left ventricular papillary muscle and right and left ventricles, 5 mm-thick images were better than 10 mm-thick images. Edges of ventricular septum and left ventricular wall were more clearly visualized on 5 mm-thick images than 10 mm-thick images. Two mm-thick MR images obtained from 2 patients yielded the most excellent visualization in end-systole, but failed to reveal cardiac structures in detail in end-diastole. Phantom studies revealed no significant differences in image quality of 10 mm and 5 mm in thickness in the axial view 80 degree to the long axis. In the axial view 45 degree to the long axis, 10 mm-thick images were inferior to 5 mm-thick images in detecting the edge of the septum and the left ventricular wall. These results indicate that the selection of slice thickness is one of the most important determinant factors in the measurement of left ventricular wall thickness and cavity dimension. (Namekawa, K).

  9. Influence of slice thickness on the determination of left ventricular wall thickness and dimension by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato

    1989-01-01

    Wall thickness of the ventricular septum and left ventricle, and left ventricular cavity dimension were determined on magnetic resonance (MR) images with slices 5 mm and 10 mm in thickness. Subjects were 3 healthy volunteers and 7 patients with hypertension (4), hypertrophic cardiomyopathy (one) or valvular heart disease (2). In visualizing the cardiac structures such as left ventricular papillary muscle and right and left ventricles, 5 mm-thick images were better than 10 mm-thick images. Edges of ventricular septum and left ventricular wall were more clearly visualized on 5 mm-thick images than 10 mm-thick images. Two mm-thick MR images obtained from 2 patients yielded the most excellent visualization in end-systole, but failed to reveal cardiac structures in detail in end-diastole. Phantom studies revealed no significant differences in image quality of 10 mm and 5 mm in thickness in the axial view 80 degree to the long axis. In the axial view 45 degree to the long axis, 10 mm-thick images were inferior to 5 mm-thick images in detecting the edge of the septum and the left ventricular wall. These results indicate that the selection of slice thickness is one of the most important determinant factors in the measurement of left ventricular wall thickness and cavity dimension. (Namekawa, K)

  10. Automated Estimation of Melanocytic Skin Tumor Thickness by Ultrasonic Radiofrequency Data.

    Science.gov (United States)

    Andrekute, Kristina; Valiukeviciene, Skaidra; Raisutis, Renaldas; Linkeviciute, Gintare; Makstiene, Jurgita; Kliunkiene, Renata

    2016-05-01

    High-frequency (>20-MHz) ultrasound (US) is a noninvasive preoperative tool for assessment of melanocytic skin tumor thickness. Ultrasonic melanocytic skin tumor thickness estimation is not always easy and is related to the experience of the clinician. In this article, we present an automated thickness measurement method based on time-frequency analysis of US radiofrequency signals. The study was performed on 52 thin (≤1-mm) melanocytic skin tumors (46 melanocytic nevi and 6 melanomas). Radiofrequency signals were obtained with a single-element focused transducer (fundamental frequency, 22 MHz; bandwidth, 12-28 MHz). The radiofrequency data were analyzed in the time-frequency domain to make the tumor boundaries more noticeable. The thicknesses of the tumors were evaluated by 3 different metrics: histologically measured Breslow thickness, manually measured US thickness, and automatically measured US thickness. The results showed a higher correlation coefficient between the automatically measured US thickness and Breslow thickness (r= 0.83; Pmeasured US thickness (r = 0.68; P measurement algorithm was 96.55%, and the specificity was 78.26% compared with histologic measurement. The sensitivity of the manually measured US thickness was 75.86%, and the specificity was 73.91%. The efficient automated tumor thickness measurement method developed could be used as a tool for preoperative assessment of melanocytic skin tumor thickness. © 2016 by the American Institute of Ultrasound in Medicine.

  11. Uncertainty estimation of ultrasonic thickness measurement

    International Nuclear Information System (INIS)

    Yassir Yassen, Abdul Razak Daud; Mohammad Pauzi Ismail; Abdul Aziz Jemain

    2009-01-01

    The most important factor that should be taken into consideration when selecting ultrasonic thickness measurement technique is its reliability. Only when the uncertainty of a measurement results is known, it may be judged if the result is adequate for intended purpose. The objective of this study is to model the ultrasonic thickness measurement function, to identify the most contributing input uncertainty components, and to estimate the uncertainty of the ultrasonic thickness measurement results. We assumed that there are five error sources significantly contribute to the final error, these sources are calibration velocity, transit time, zero offset, measurement repeatability and resolution, by applying the propagation of uncertainty law to the model function, a combined uncertainty of the ultrasonic thickness measurement was obtained. In this study the modeling function of ultrasonic thickness measurement was derived. By using this model the estimation of the uncertainty of the final output result was found to be reliable. It was also found that the most contributing input uncertainty components are calibration velocity, transit time linearity and zero offset. (author)

  12. Faraday effect in hollow quantum cylinder of finite thickness

    International Nuclear Information System (INIS)

    Ismailov, T.G.; Jabrailova, G.G.

    2009-01-01

    The interband Faraday rotation in hollow quantum cylinder of finite thickness is theoretically investigated. Faraday rotation in the dependence on incident light energy for different values of cylinder thickness. It is seen that the resonance peaks appear on Faraday rotation curve. The roles of selection are obtained

  13. Ferroelectric domain inversion and its stability in lithium niobate thin film on insulator with different thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Guang-hao; Bai, Yu-hang; Cui, Guo-xin; Li, Chen; Qiu, Xiang-biao; Wu, Di; Lu, Yan-qing, E-mail: yqlu@nju.edu.cn [National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Geng, De-qiang [Jinan Jingzheng Electronics Co., Ltd., Jinan 250100 (China)

    2016-07-15

    Ferroelectric domain inversion and its effect on the stability of lithium niobate thin films on insulator (LNOI) are experimentally characterized. Two sets of specimens with different thicknesses varying from submicron to microns are selected. For micron thick samples (∼28 μm), domain structures are achieved by pulsed electric field poling with electrodes patterned via photolithography. No domain structure deterioration has been observed for a month as inspected using polarizing optical microscopy and etching. As for submicron (540 nm) films, large-area domain inversion is realized by scanning a biased conductive tip in a piezoelectric force microscope. A graphic processing method is taken to evaluate the domain retention. A domain life time of 25.0 h is obtained and possible mechanisms are discussed. Our study gives a direct reference for domain structure-related applications of LNOI, including guiding wave nonlinear frequency conversion, nonlinear wavefront tailoring, electro-optic modulation, and piezoelectric devices.

  14. Design and optimization of the low frequency eddy current technique for the volumetric inspection of austenitic small diameter tubes with a wall thickness up to 12 mm; Auslegung und Optimierung des Niederfrequenz-Wirbelstrom-Verfahrens fuer die volumetrische Pruefung von austenitischen Neben- und Kleinleitungen mit Wandstaerken bis 12 mm

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R; Bessert, S; Disque, M; Weiss, R [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany)

    1998-11-01

    The low-frequency eddy current technique discussed is a suitable external inspection technique detecting defects at the inner walls of small-diameter tubes and measuring their depths via the ligament. A testing system with optimized sensor lus software for image recording, evaluation, display and documentation is available. The current state of development of the system permits detection and measurement of defects up to 20 mm in size in austenitic inner walls 12.5 mm thick down to a depth of 3 mm. This applies both to the homogenous base metal and the weld with {delta} ferrite. (orig./CB) [Deutsch] Das vorgestellte Niederfrequenz-Wirbelstrom-Verfahren ist geeignet, bei Pruefung von aussen Fehler an der Innenseite von Klein- und Nebenleitungen nachzuweisen und ueber das Ligament deren Tiefe zu bestimmen. Ein entsprechendes Pruefsystem mit optimiertem Sensor und der Software zur Aufnahme, Auswertung, Darstellung und Dokumentation der Wirbelstrom-Urdaten steht zur Verfuegung. Beim jetzigen Entwicklungsstand liegt die Nachweisgrenze fuer einen 20 mm langen Innenfehler in einer 12.5 mm dicken austenitischen Wandung bei einer Fehlertiefe von 3 mm. Dies gilt sowohl fuer den homogenen Grundwerkstoff als auch fuer Schweissgefuege mit {delta}-Ferrit. (orig./MM)

  15. Static and dynamic through thickness lamina properties of thick laminates

    NARCIS (Netherlands)

    Lahuerta, F.; Nijssen, R.P.L.; Van der Meer, F.P.; Sluys, L.J.

    2015-01-01

    Thick laminates are increasingly present in large composites structures such as wind turbine blades. Different factors are suspected to be involved in the decreased static and dynamic performance of thick laminates. These include the effect of self-heating, the scaling effect, and the manufacturing

  16. A theoretical analysis of the response of an air-cored eddy current coil for remote oxide thickness measurements on reactor components

    International Nuclear Information System (INIS)

    Wilson, R.

    1979-10-01

    It is shown how the impedance of an air-cored eddy current coil in close proximity to an oxidised steel component may be calculated. Representative values were selected for the oxide thickness, lift off, operating frequency, conductivities and permeabilities of the oxide coating and steel base. The values of these parameters in the calculations were allowed to vary between suitable limits to quantify the effect of each one on coil impedance. The results of the calculations are used to determine the most suitable conditions for the measurement of oxide thickness on steel components using an air-cored eddy current probe. (author)

  17. Storm-time slab thickness at low latitudes

    International Nuclear Information System (INIS)

    Chauhan, N.S.; Gurm, H.S.

    1981-01-01

    The ATS-6 data for a period of 1975-76 is used for the study of slab thickness during two moderate storms (Ksub(p) - ) around the crest of the anomaly, Ahmedabad and a very great (Ksub(p) + ) outside the equatorial anomaly region, Delhi. While at Ahmedabad, on the average, the slab thickness is found to be above the frequency. Comparison of slab thickness with foF2 and the equatorial magnetic record (for Ahmedabad only) shows that the foF2 changes alone cannot be held responsible for the slab thickness variation and thus entry of the plasma flux from the plasmasphere cannot be ruled out. The pressure variation effect of storm-time heating on the slab thickness at Ahmedabad is that even for Ksub(p)=8, the thermal expansion and the contraction effects are unable to explain complete quantitative and qualitative features of the observations

  18. Optimum target thickness for polarimeters

    International Nuclear Information System (INIS)

    Sitnik, I.M.

    2003-01-01

    Polarimeters with thick targets are a tool to measure the proton polarization. But the question about the optimum target thickness is still the subject of discussion. An attempt to calculate the most common parameters concerning this problem, in a few GeV region, is made

  19. Effect of length to thickness ratio on free vibration analysis of thick fiber reinforced plastic skew cross-ply laminate with circular cutout

    Science.gov (United States)

    Srividya, K.; Reddy, Ch. Kishore; Sumanth, Ch. Mohan; Krishnaiah, P. Gopala; Kishan, V. Mallikharjuna

    2018-04-01

    The present investigation deals with the free vibration analysis of a thick four-layered symmetric cross-ply skew laminated composite plate with a circular cutout. Three dimensional finite element models (FEM) which use the elasticity theory for the determination of stiffness matrices are modeled in ANSYS software to evaluate first five natural frequencies of the laminate. The variations of the first five natural frequencies with respect to length to thickness ratio (S) for different diameter to length ratios (d/l) are presented. It is observed that, the natural frequencies decreases with increase of thickness ratio(S).

  20. Detecting correlation between allele frequencies and environmental variables as a signature of selection. A fast computational approach for genome-wide studies

    DEFF Research Database (Denmark)

    Guillot, Gilles; Vitalis, Renaud; Rouzic, Arnaud le

    2014-01-01

    to disentangle the potential effect of environmental variables from the confounding effect of population history. For the routine analysis of genome-wide datasets, one also needs fast inference and model selection algorithms. We propose a method based on an explicit spatial model which is an instance of spatial...... for the most common types of genetic markers, obtained either at the individual or at the population level. Analyzing the simulated data produced under a geostatistical model then under an explicit model of selection, we show that the method is efficient. We also re-analyze a dataset relative to nineteen pine...

  1. Properties of conductive thick-film inks

    Science.gov (United States)

    Holtze, R. F.

    1972-01-01

    Ten different conductive inks used in the fabrication of thick-film circuits were evaluated for their physical and handling properties. Viscosity, solid contents, and spectrographic analysis of the unfired inks were determined. Inks were screened on ceramic substrates and fired for varying times at specified temperatures. Selected substrates were given additional firings to simulate the heat exposure received if thick-film resistors were to be added to the same substrate. Data are presented covering the (1) printing characteristics, (2) solderability using Sn-63 and also a 4 percent silver solder, (3) leach resistance, (4) solder adhesion, and (5) wire bonding properties. Results obtained using different firing schedules were compared. A comparison was made between the various inks showing general results obtained for each ink. The changes in firing time or the application of a simulated resistor firing had little effect on the properties of most inks.

  2. METALLICITY GRADIENTS OF THICK DISK DWARF STARS

    Energy Technology Data Exchange (ETDEWEB)

    Carrell, Kenneth; Chen Yuqin; Zhao Gang, E-mail: carrell@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2012-12-01

    We examine the metallicity distribution of the Galactic thick disk using F, G, and K dwarf stars selected from the Sloan Digital Sky Survey, Data Release 8. Using the large sample of dwarf stars with proper motions and spectroscopically determined stellar parameters, metallicity gradients in the radial direction for various heights above the Galactic plane and in the vertical direction for various radial distances from the Galaxy center have been found. In particular, we find a vertical metallicity gradient of -0.113 {+-} 0.010 (-0.125 {+-} 0.008) dex kpc{sup -1} using an isochrone (photometric) distance determination in the range 1 kpc <|Z| < 3 kpc, which is the vertical height range most consistent with the thick disk of our Galaxy. In the radial direction, we find metallicity gradients between +0.02 and +0.03 dex kpc{sup -1} for bins in the vertical direction between 1 kpc <|Z| < 3 kpc. Both of these results agree with similar values determined from other populations of stars, but this is the first time a radial metallicity gradient for the thick disk has been found at these vertical heights. We are also able to separate thin and thick disk stars based on kinematic and spatial probabilities in the vertical height range where there is significant overlap of these two populations. This should aid further studies of the metallicity gradients of the disk for vertical heights lower than those studied here but above the solar neighborhood. Metallicity gradients in the thin and thick disks are important probes into possible formation scenarios for our Galaxy and a consistent picture is beginning to emerge from results using large spectroscopic surveys, such as the ones presented here.

  3. Frequency standards

    CERN Document Server

    Riehle, Fritz

    2006-01-01

    Of all measurement units, frequency is the one that may be determined with the highest degree of accuracy. It equally allows precise measurements of other physical and technical quantities, whenever they can be measured in terms of frequency.This volume covers the central methods and techniques relevant for frequency standards developed in physics, electronics, quantum electronics, and statistics. After a review of the basic principles, the book looks at the realisation of commonly used components. It then continues with the description and characterisation of important frequency standards

  4. Trochanteric Soft Tissue Thickness and Hip Fracture in Older Men

    Science.gov (United States)

    Nielson, Carrie M.; Bouxsein, Mary L.; Freitas, Sinara S.; Ensrud, Kristine E.; Orwoll, Eric S.

    2009-01-01

    Background: Greater thickness of the tissue extending laterally from the greater trochanter has been associated with a lower risk of hip fracture in women. The effect of trochanteric soft tissue thickness on the risk of incident hip fracture has not been evaluated in men. Methods: We measured trochanteric soft tissue thickness by dual-energy x-ray absorptiometry for all incident hip fracture cases (n = 70) and 222 randomly selected noncases in older men (≥65 yr) enrolled in the Osteoporotic Fractures in Men (MrOS) Study. Differences in tissue thickness between cases and controls were examined. Changes in fall force and factor-of-risk (the ratio of force from a sideways fall to femoral bone strength) associated with tissue thickness were determined. The relative risk for incident hip fracture per sd decrease in tissue thickness was calculated. Results: Mean trochanteric soft tissue thickness did not differ significantly between cases and noncases (29.1 ± 11.9 vs 31.0 ± 11.5 mm; P = 0.2). Although increased tissue thickness reduced both the estimates of fall force and the factor-of-risk, tissue thickness was not associated with the risk of hip fracture (age- and bone mineral density-adjusted relative risk per sd decrease in tissue thickness = 0.90; 95% confidence interval, 0.70–1.16). Conclusions: In this study of elderly community-dwelling men, we found no significant association between trochanteric soft tissue thickness and incident hip fracture. Trochanteric soft tissue thickness in these men was less than previously reported in older women and may explain the difference between these results and those reported in women. PMID:19017753

  5. Thickness measurement instrument with memory storage of multiple calibrations

    International Nuclear Information System (INIS)

    Lieber, S.; Schlesinger, J.; Lieber, D.; Baker, A.

    1979-01-01

    An improved backscatter instrument for the nondestructive measurement of coatings on a substrate is described. A memory having selectable memory areas, each area having stored intelligence available which is determinative of the shape of a functional plot of coating thickness versus backscatter counts per minute unique for each particular combination of emitting isotope, substrate material, coating material and physical characteristics of the measuring instrument. A memory selector switch connects a selected area of memory to a microprocessor operating under program control whereby the microprocessor reads the intelligence stored at the selected area and converts the backscattered count of the coating being measured into indicia of coating thickness

  6. Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films.

    Science.gov (United States)

    Duangdee, Chatnapa; Tangpukdee, Noppadon; Krudsood, Srivicha; Wilairatana, Polrat

    2012-04-01

    To determine the frequency of malaria parasite detection from the buffy coat blood films by using capillary tube in falciparum malaria patients with negative conventional thick films. Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study. The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases, Bangkok, Thailand for 28 day. Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia, then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film. The first negative conventional thick films were compared with buffy coat thick films for parasite identification. Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients (27.8%) with asexual forms of Plasmodium falciparum. The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8% of patients whose conventional thick films show negative parasitemia.

  7. Bit Error Rate Performance of a MIMO-CDMA System Employing Parity-Bit-Selected Spreading in Frequency Nonselective Rayleigh Fading

    Directory of Open Access Journals (Sweden)

    Claude D'Amours

    2011-01-01

    Full Text Available We analytically derive the upper bound for the bit error rate (BER performance of a single user multiple input multiple output code division multiple access (MIMO-CDMA system employing parity-bit-selected spreading in slowly varying, flat Rayleigh fading. The analysis is done for spatially uncorrelated links. The analysis presented demonstrates that parity-bit-selected spreading provides an asymptotic gain of 10log(Nt dB over conventional MIMO-CDMA when the receiver has perfect channel estimates. This analytical result concurs with previous works where the (BER is determined by simulation methods and provides insight into why the different techniques provide improvement over conventional MIMO-CDMA systems.

  8. Corneal thickness: measurement and implications.

    Science.gov (United States)

    Ehlers, Niels; Hjortdal, Jesper

    2004-03-01

    The thickness of the cornea was reported in more than 100-year-old textbooks on physiological optics (Helmholtz, Gullstrand). Physiological interest was revived in the 1950s by David Maurice, and over the next 50 years, this 'simple' biological parameter has been studied extensively. Several techniques for its measurement have been described and physiological and clinical significance have been studied. In this review, the different methods and techniques of measurement are briefly presented (optical, ultrasound). While the corneal thickness of many animals are the same over a considerable part of the surface, in the human cornea anterior and posterior curvature are not concentric giving rise to a problem of definition. Based on this the precision and accuracy of determining the central corneal thickness are discussed. Changes in corneal thickness reflects changes in function of the boundary layers, in particular the endothelial barrier. The absolute value of thickness is of importance for the estimation of IOP but also in diagnosis of corneal and systemic disorders. Finally it is discussed to what extent the thickness is a biometric parameter of significance, e.g. in the progression of myopia or in the development of retinal detachment.

  9. Frequency Synthesiser

    NARCIS (Netherlands)

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus M.W.; Breems, Lucien J.; Nauta, Bram

    2016-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  10. Frequency synthesiser

    NARCIS (Netherlands)

    Drago, S.; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram

    2010-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  11. Frequency-specific attentional modulation in human primary auditory cortex and midbrain

    NARCIS (Netherlands)

    Riecke, Lars; Peters, Judith C; Valente, Giancarlo; Poser, Benedikt A; Kemper, Valentin G; Formisano, Elia; Sorger, Bettina

    2018-01-01

    Paying selective attention to an audio frequency selectively enhances activity within primary auditory cortex (PAC) at the tonotopic site (frequency channel) representing that frequency. Animal PAC neurons achieve this 'frequency-specific attentional spotlight' by adapting their frequency tuning,

  12. Endoscopic full-thickness resection: Current status.

    Science.gov (United States)

    Schmidt, Arthur; Meier, Benjamin; Caca, Karel

    2015-08-21

    Conventional endoscopic resection techniques such as endoscopic mucosal resection or endoscopic submucosal dissection are powerful tools for treatment of gastrointestinal neoplasms. However, those techniques are restricted to superficial layers of the gastrointestinal wall. Endoscopic full-thickness resection (EFTR) is an evolving technique, which is just about to enter clinical routine. It is not only a powerful tool for diagnostic tissue acquisition but also has the potential to spare surgical therapy in selected patients. This review will give an overview about current EFTR techniques and devices.

  13. Wall thickness measurements using digital radiography - state of the art

    International Nuclear Information System (INIS)

    Wawrzinek, T.; Zscherpel, U.; Bellon, C.

    1997-01-01

    Projection radiography is a method long since used for wall thickness measurements in pipes. Another method sometimes applied is thickness determination based on measuring changes of the optical density by using radioactive isotopes, as in this case the effects of stray radiation are negligible. The two methods hitherto were to be performed manually, and wall thickness data were derived by calculations with a pocket calculator. The required measuring and calculating work can now be automated by way of computerized processing of digitised images. The paper presents the software for automated evaluation of data of a selected location after system calibration. (orig./CB) [de

  14. Terahertz thickness determination with interferometric vibration correction for industrial applications.

    Science.gov (United States)

    Pfeiffer, Tobias; Weber, Stefan; Klier, Jens; Bachtler, Sebastian; Molter, Daniel; Jonuscheit, Joachim; Von Freymann, Georg

    2018-05-14

    In many industrial fields, like automotive and painting industry, the thickness of thin layers is a crucial parameter for quality control. Hence, the demand for thickness measurement techniques continuously grows. In particular, non-destructive and contact-free terahertz techniques access a wide range of thickness determination applications. However, terahertz time-domain spectroscopy based systems perform the measurement in a sampling manner, requiring fixed distances between measurement head and sample. In harsh industrial environments vibrations of sample and measurement head distort the time-base and decrease measurement accuracy. We present an interferometer-based vibration correction for terahertz time-domain measurements, able to reduce thickness distortion by one order of magnitude for vibrations with frequencies up to 100 Hz and amplitudes up to 100 µm. We further verify the experimental results by numerical calculations and find very good agreement.

  15. Universal Rim Thickness in Unsteady Sheet Fragmentation

    Science.gov (United States)

    Wang, Y.; Dandekar, R.; Bustos, N.; Poulain, S.; Bourouiba, L.

    2018-05-01

    Unsteady fragmentation of a fluid bulk into droplets is important for epidemiology as it governs the transport of pathogens from sneezes and coughs, or from contaminated crops in agriculture. It is also ubiquitous in industrial processes such as paint, coating, and combustion. Unsteady fragmentation is distinct from steady fragmentation on which most theoretical efforts have been focused thus far. We address this gap by studying a canonical unsteady fragmentation process: the breakup from a drop impact on a finite surface where the drop fluid is transferred to a free expanding sheet of time-varying properties and bounded by a rim of time-varying thickness. The continuous rim destabilization selects the final spray droplets, yet this process remains poorly understood. We combine theory with advanced image analysis to study the unsteady rim destabilization. We show that, at all times, the rim thickness is governed by a local instantaneous Bond number equal to unity, defined with the instantaneous, local, unsteady rim acceleration. This criterion is found to be robust and universal for a family of unsteady inviscid fluid sheet fragmentation phenomena, from impacts of drops on various surface geometries to impacts on films. We discuss under which viscous and viscoelastic conditions the criterion continues to govern the unsteady rim thickness.

  16. Color selectivity of surface-plasmon holograms illuminated with white light.

    Science.gov (United States)

    Ozaki, Miyu; Kato, Jun-ichi; Kawata, Satoshi

    2013-09-20

    By using the optical frequency dependence of surface-plasmon polaritons, color images can be reconstructed from holograms illuminated with white light. We report details on the color selectivity of the color holograms. The selectivity is tuned by the thickness of a dielectric film covering a plasmonic metal film. When the dielectric is SiO(2) and the metal is silver, the appropriate thicknesses are 25 and 55 nm, respectively. In terms of spatial color uniformity, holograms made of silver-film corrugations are better than holograms recorded on photographic film on a flat silver surface.

  17. Chemical constraints on the formation of the Galactic thick disk

    Directory of Open Access Journals (Sweden)

    Feltzing S.

    2012-02-01

    Full Text Available We highlight some results from our detailed abundance analysis study of 703 kinematically selected F and G dwarf stars in the solar neighbourhood. The analysis is based on spectra of high-resolution (R = 45000 to 110 000 and high signal-to-noise (S/N ≈ 150 to 300. The main findings include: (1 at a given metallicity, the thick disk abundance trends are more α-enhanced than those of the thin disk; (2 the metal-rich limit of the thick disk reaches at least solar metallicities; (3 the metal-poor limit of the thin disk is around [Fe/H] ≈−0.8; (4 the thick disk shows an age-metallicity gradient; (5 the thin disk does not show an age-metallicity gradient; (6 the most metal-rich thick disk stars at [Fe/H] ≈ 0 are significantly older than the most metal-poor thin disk stars at [Fe/H] ≈−0.7; (7 based on our elemental abundances we find that kinematical criteria produce thin and thick disk stellar samples that are biased in the sense that stars from the low-velocity tail of the thick disk are classified as thin disk stars, and stars from the high-velocity tail of the thin disk are classified as thick disk stars; (8 age criteria appears to produce thin and thick disk stellar samples with less contamination.

  18. Axisymmetric vibrations of thick shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)

  19. Mode Identification of Guided Ultrasonic Wave using Time- Frequency Algorithm

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Yang, Seung Han; Cho, Yong Sang; Kim, Yong Sik; Lee, Hee Jong

    2007-01-01

    The ultrasonic guided waves are waves whose propagation characteristics depend on structural thickness and shape such as those in plates, tubes, rods, and embedded layers. If the angle of incidence or the frequency of sound is adjusted properly, the reflected and refracted energy within the structure will constructively interfere, thereby launching the guided wave. Because these waves penetrate the entire thickness of the tube and propagate parallel to the surface, a large portion of the material can be examined from a single transducer location. The guided ultrasonic wave has various merits like above. But various kind of modes are propagating through the entire thickness, so we don't know the which mode is received. Most of applications are limited from mode selection and mode identification. So the mode identification is very important process for guided ultrasonic inspection application. In this study, various time-frequency analysis methodologies are developed and compared for mode identification tool of guided ultrasonic signal. For this study, a high power tone-burst ultrasonic system set up for the generation and receive of guided waves. And artificial notches were fabricated on the Aluminum plate for the experiment on the mode identification

  20. Are galaxy discs optically thick?

    International Nuclear Information System (INIS)

    Disney, Michael; Davies, Jonathan; Phillipps, Steven

    1989-01-01

    We re-examine the classical optical evidence for the low optical depths traditionally assigned to spiral discs and argue that it is highly model-dependent and unconvincing. In particular, layered models with a physically thin but optically thick dust layer behave like optically thin discs. The opposite hypotheses, that such discs are optically thick is then examined in the light of modern evidence. We find it to be consistent with the near-infrared and IRAS observations, with the surface brightnesses, with the HI and CO column densities and with the Hα measurements. (author)

  1. Nondestructive Evaluation of Thick Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dwight A [ORNL

    2015-01-01

    Materials issues are a key concern for the existing nuclear reactor fleet in the United States as material degradation can lead to increased maintenance, increased downtime, and increased risk. Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of both known and new forms of degradation. A multitude of concrete-based structures are typically part of a light water reactor plant to provide foundation, support, shielding, and containment functions. The size and complexity of nuclear power plant containment structures and the heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. This paper examines the benefits of using time-frequency analysis with Synthetic Aperture Focusing Technique (SAFT). By using wavelet packet decomposition, the original ultrasound signals are decomposed into various frequency bands that facilitates highly selective analysis of the signal’s frequency content and can be visualized using the familiar SAFT image reconstruction algorithm.

  2. The Effect of Subcutaneous Fat on Electrical Impedance Myography: Electrode Configuration and Multi-Frequency Analyses.

    Directory of Open Access Journals (Sweden)

    Le Li

    Full Text Available This study investigates the impact of the subcutaneous fat layer (SFL thickness on localized electrical impedance myography (EIM, as well as the effects of different current electrodes, varying in distance and direction, on EIM output. Twenty-three healthy subjects underwent localized multi-frequency EIM on their biceps brachii muscles with a hand-held electrode array. The EIM measurements were recorded under three different configurations: wide (or outer longitudinal configuration 6.8 cm, narrow (or inner longitudinal configuration 4.5 cm, and narrow transverse configuration 4.5 cm. Ultrasound was applied to measure the SFL thickness. Coefficients of determination (R2 of three EIM variables (resistance, reactance, and phase and SFL thickness were calculated. For the longitudinal configuration, the wide distance could reduce the effects of the subcutaneous fat when compared with the narrow distance, but a significant correlation still remained for all three EIM parameters. However, there was no significant correlation between SFL thickness and reactance in the transverse configuration (R2 = 0.0294, p = 0.434. Utilizing a ratio of 50kHz/100kHz phase was found to be able to help reduce the correlation with SFL thickness for all the three configurations. The findings indicate that the appropriate selection of the current electrode distance, direction and the multi-frequency phase ratio can reduce the impact of subcutaneous fat on EIM. These settings should be evaluated for future clinical studies using hand-held localized arrays to perform EIM.

  3. Dielectric measurements on PWB materials at microwave frequencies

    Indian Academy of Sciences (India)

    Unknown

    the angular frequency and c0 the velocity of light, c the thickness of the ... Dielectric parameters, absorption index and refractive index for pure PSF and pure PMMA at 8⋅92 GHz frequency and at 35°C temperature. Dielectric. Dielectric. Loss. Relaxation. Conductivity Absorption. Refractive. Thickness, constant loss tangent.

  4. Behavioral estimates of human frequency selectivity at low frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado

    A fundamental property of our hearing organ is its ability to break down sound into different spectral components, allowing us to make use of the richness in natural sound phenomena. Auditory filters, which conceptualize this property of the ear, however, have not been appropriately described at ...

  5. [Endoscopic full-thickness resection].

    Science.gov (United States)

    Meier, B; Schmidt, A; Caca, K

    2016-08-01

    Conventional endoscopic resection techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) are powerful tools for the treatment of gastrointestinal (GI) neoplasms. However, those techniques are limited to the superficial layers of the GI wall (mucosa and submucosa). Lesions without lifting sign (usually arising from deeper layers) or lesions in difficult anatomic positions (appendix, diverticulum) are difficult - if not impossible - to resect using conventional techniques, due to the increased risk of complications. For larger lesions (>2 cm), ESD appears to be superior to the conventional techniques because of the en bloc resection, but the procedure is technically challenging, time consuming, and associated with complications even in experienced hands. Since the development of the over-the-scope clips (OTSC), complications like bleeding or perforation can be endoscopically better managed. In recent years, different endoscopic full-thickness resection techniques came to the focus of interventional endoscopy. Since September 2014, the full-thickness resection device (FTRD) has the CE marking in Europe for full-thickness resection in the lower GI tract. Technically the device is based on the OTSC system and combines OTSC application and snare polypectomy in one step. This study shows all full-thickness resection techniques currently available, but clearly focuses on the experience with the FTRD in the lower GI tract.

  6. Frequency spirals

    International Nuclear Information System (INIS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-01-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  7. Frequency spirals

    Energy Technology Data Exchange (ETDEWEB)

    Ottino-Löffler, Bertrand; Strogatz, Steven H., E-mail: strogatz@cornell.edu [Center for Applied Mathematics, Cornell University, Ithaca, New York 14853 (United States)

    2016-09-15

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  8. Gammatography of thick lead vessels

    International Nuclear Information System (INIS)

    Raghunath, V.M.; Bhatnagar, P.K.; Sundaram, V.M.

    1979-01-01

    Radiography, scintillation and GM counting and dose measurements using ionisation chamber equipment are commonly used for detecting flaws/voids in materials. The first method is mostly used for steel vessels and to a lesser extent thin lead vessels also and is essentially qualitative. Dose measuring techniques are used for very thick and large lead vessels for which high strength radioactive sources are required, with its inherent handling problems. For vessels of intermediate thicknesses, it is ideal to use a small strength source and a GM or scintillation counter assembly. At the Reactor Research Centre, Kalpakkam, such a system was used for checking three lead vessels of thicknesses varying from 38mm to 65mm. The tolerances specified were +- 4% variation in lead thickness. The measurements also revealed the non concentricity of one vessel which had a thickness varying from 38mm to 44mm. The second vessel was patently non-concentric and the dimensional variation was truly reproduced in the measurements. A third vessel was fabricated with careful control of dimensions and the measurements exhibited good concentricity. Small deviations were observed, attributable to imperfect bondings between steel and lead. This technique has the following advantages: (a) weaker sources used result in less handling problems reducing the personnel exposures considerably; (b) the sensitivity of the instrument is quite good because of better statistics; (c) the time required for scanning a small vessel is more, but a judicious use of a scintillometer for initial fast scan will help in reducing the total scanning time; (d) this method can take advantage of the dimensional variations themselves to get the calibration and to estimate the deviations from specified tolerances. (auth.)

  9. Thick resist for MEMS processing

    Science.gov (United States)

    Brown, Joe; Hamel, Clifford

    2001-11-01

    The need for technical innovation is always present in today's economy. Microfabrication methods have evolved in support of the demand for smaller and faster integrated circuits with price performance improvements always in the scope of the manufacturing design engineer. The dispersion of processing technology spans well beyond IC fabrication today with batch fabrication and wafer scale processing lending advantages to MEMES applications from biotechnology to consumer electronics from oil exploration to aerospace. Today the demand for innovative processing techniques that enable technology is apparent where only a few years ago appeared too costly or not reliable. In high volume applications where yield and cost improvements are measured in fractions of a percent it is imperative to have process technologies that produce consistent results. Only a few years ago thick resist coatings were limited to thickness less than 20 microns. Factors such as uniformity, edge bead and multiple coatings made high volume production impossible. New developments in photoresist formulation combined with advanced coating equipment techniques that closely controls process parameters have enable thick photoresist coatings of 70 microns with acceptable uniformity and edge bead in one pass. Packaging of microelectronic and micromechanical devices is often a significant cost factor and a reliability issue for high volume low cost production. Technologies such as flip- chip assembly provide a solution for cost and reliability improvements over wire bond techniques. The processing for such technology demands dimensional control and presents a significant cost savings if it were compatible with mainstream technologies. Thick photoresist layers, with good sidewall control would allow wafer-bumping technologies to penetrate the barriers to yield and production where costs for technology are the overriding issue. Single pass processing is paramount to the manufacturability of packaging

  10. The research of device for measuring film thickness of intelligent coating machine

    Directory of Open Access Journals (Sweden)

    Wang Wanjun

    2015-01-01

    Full Text Available Ion beam sputtering machine uses computer to real time monitor the change of film thickness in the preparation process of soft X ray multilayer element fabrication. It solves the problems of uneven film thickness and too thick film thickness and so on, which exist in the original preparation process. The high-precision quartz crystal converts film thickness measurement into frequency measurement. The equal precision frequency meter based on FPGA measures the frequency. It can reduce the signal delay and interference signal of discrete components, accordingly improving the accuracy of measurement. Then it sents the count value to the host computer through the single chip microcomputer serial port. It calculates and displays the value by the GUI of LabVIEW. The experimental results show that, the relative measurement error can be decreased to 1/10, i.e., the measurement accuracy can be improved by more than ten times.

  11. Obtaining thickness profiles from the tomographic inversion of guided wave data

    NARCIS (Netherlands)

    Bloom, J.G.P.; Luiten, E.A.; Volker, A.W.F.

    2009-01-01

    Guided wave tomography is a promising technique for the monitoring of corrosion over large areas. Guided waves have a wave speed mat depends in certain frequency-thickness regimes on the local thickness of the waveguide they follow. Therefore, the travel time of the guided wave over a fixed distance

  12. 3D electroplated inductors with thickness variation for improved broadband performance

    Science.gov (United States)

    Farm-Guoo Tseng, Victor; Bedair, Sarah S.; Lazarus, Nathan

    2017-01-01

    The performance of an RF spiral inductor is based on the balance between ohmic losses in the outer turns and eddy current losses dominant in the inner turns where the magnetic field is the strongest. In this work, air-core spiral inductors with winding trace thicknesses decreasing towards the center are demonstrated, achieving quality factor improvement over a wide frequency range compared to uniform thickness inductors. A custom 3D copper electroplating process was used to produce spiral inductors with varying winding thicknesses in a single plating step, with patterned gaps in a seed layer used to create delays in the vertical plating. The fabricated center-lowered coil inductors were 80 nH within a one square millimeter area with thickness varying from 60 µm to 10 µm from outer to inner winding. Within the 16 MHz-160 MHz range, the center-lowered inductors were shown to have a maximum to minimum quality factor improvement of 90%-10% when compared to uniform thickness inductors with thicknesses ranging from 60 µm to 10 µm. Compared to the 20 µm uniform thickness inductor which has the optimal performance among all uniform thickness inductors in this frequency range, the center-lowered inductors were shown to achieve a maximum quality factor improvement of 20% at the edge frequencies of 16 MHz and 160 MHz, and a minimum quality factor improvement of 10% near the geometric mean center frequency of 46 MHz.

  13. Accurate thickness measurement of graphene

    International Nuclear Information System (INIS)

    Shearer, Cameron J; Slattery, Ashley D; Stapleton, Andrew J; Shapter, Joseph G; Gibson, Christopher T

    2016-01-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1–1.3 nm to 0.1–0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials. (paper)

  14. Soliton models for thick branes

    International Nuclear Information System (INIS)

    Peyravi, Marzieh; Riazi, Nematollah; Lobo, Francisco S.N.

    2016-01-01

    In this work, we present new soliton solutions for thick branes in 4+1 dimensions. In particular, we consider brane models based on the sine-Gordon (SG), φ 4 and φ 6 scalar fields, which have broken Z 2 symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the w 2 term in the expansion of the potential for the resulting Schroedinger-like equation, where w is the five-dimensional coordinate. It turns out that the φ 4 brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and φ 6 branes. (orig.)

  15. Soliton models for thick branes

    Energy Technology Data Exchange (ETDEWEB)

    Peyravi, Marzieh [Ferdowsi University of Mashhad, Department of Physics, School of Sciences, Mashhad (Iran, Islamic Republic of); Riazi, Nematollah [Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Lobo, Francisco S.N. [Faculdade de Ciencias da Universidade de Lisboa, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal)

    2016-05-15

    In this work, we present new soliton solutions for thick branes in 4+1 dimensions. In particular, we consider brane models based on the sine-Gordon (SG), φ{sup 4} and φ{sup 6} scalar fields, which have broken Z{sub 2} symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the w{sup 2} term in the expansion of the potential for the resulting Schroedinger-like equation, where w is the five-dimensional coordinate. It turns out that the φ{sup 4} brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and φ{sup 6} branes. (orig.)

  16. BaTiO3 thick fi lms obtained by tape casting from powders prepared by the oxalate route

    Directory of Open Access Journals (Sweden)

    Adelina Ianculescu

    2009-06-01

    Full Text Available BaTiO3 powders were prepared by co-precipitation via oxalate route. The size, morphology and particle size distribution of the oxalate powders have been optimized by the control of different synthesis parameters during the precipitation reaction (nature of salts, concentration of different solutions, aging time. The single phase BaTiO3 oxide particles were obtained after a thermal decomposition of the as-synthesized powders at 850°C for 4 hours under air atmosphere. Oxide powders with a suitable specifi c surface area were selected in order to obtain thick fi lms by the tape casting technique. The microstructure and dielectric properties of the thick films varied obviously depending on the deposition-calcination-sintering cycle used. A double depositioncalcination cycle followed by sintering, as well as a two step deposition-calcination-sintering procedure was used in order to improve the compactness and therefore, the dielectric behaviour. A higher dielectric constant value (~ 750 and lower dielectric losses (~ 2 % were achieved at room temperature and at 1 kHz frequency for the dense, double-deposited fi lm obtained after two deposition-calcination-sintering cycles. For this film, a superior value of the dielectric constant (~ 1100, almost frequency independent in the frequency range of 100 Hz – 10 kHz was gained also at the ferroelectric-paraelectric phase transition temperature of 130°C.

  17. Electron beam curable polymer thick film

    International Nuclear Information System (INIS)

    Nagata, Hidetoshi; Kobayashi, Takashi

    1988-01-01

    Currently, most printed circuit boards are produced by the selective etching of copper clads laminated on dielectric substrates such as paper/phenolic resion or nonwoven glass/epoxy resin composites. After the etchig, various components such as transistors and capacitors are mounted on the boards by soldering. But these are troublesome works, therefore, as an alternative, printing method has been investigated recently. In the printing method, conductor circuits and resistors can be made by printing and curing of the specially prepared paste on dielectric substrates. In the near future, also capacitors are made by same method. Usually, conductor paste, resistor paste and dielectric paste are employed, and in this case, the printing is screen printing, and the curing is done thermally. In order to avoid heating and the deterioration of substrates, attention was paid to electron beam curing, and electron beam curable polymer thick film system was developed. The electron beam curable paste is the milled mixture of a filler and an electron beam curable binder of oligomer/monomer. The major advantage of electron beam curable polymer thick film, the typical data of a printed resistor of this type and its trial are reported. (K.I.)

  18. MEMS-based thick film PZT vibrational energy harvester

    DEFF Research Database (Denmark)

    Lei, Anders; Xu, Ruichao; Thyssen, Anders

    2011-01-01

    We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechan......We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using...... a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The fabricated harvester device produces 14.0 μW with an optimal resistive load of 100 kΩ from 1g (g=9.81 m s-2) input acceleration at its resonant frequency of 235 Hz....

  19. Multi-Band Frequency Selective Surfaces: Analysis

    Science.gov (United States)

    2008-08-01

    performed by a graduate student from the University of Turin (Italy) in the frame of a six-month internship at TNO, following these steps: la Study the IEMEN...antennas using EBG substrates", Ph.D. dissertation, Departamento de Comunicaciones , Universidad Politecnica de Valencia, Valencia, Spain, 2006. [21

  20. Magnetic Probe Construction using Thick-film Technology

    International Nuclear Information System (INIS)

    Takahashi, H.; Sakakibara, S.; Kubota, Y.; Yamada, H.

    2001-01-01

    Thick-film technology has been successfully adapted for the design and fabrication of magnetic probes of a new type suitable for use in the simultaneous ultra-high vacuum and high-temperature environment of a nuclear fusion device. The maximum usable temperature is expected to be around 900 degrees C. This new probe has a specific sensitivity (coupling area per unit volume) an order of magnitude higher than a conventional coil. The new probe in one implementation is capable of simultaneously measuring magnetic field in three orthogonal directions about a single spatial point and in two frequency ranges. Low-frequency coils have a measured coupling area of 296-323 cm squared and a frequency response of about 300 kHz. High-frequency coils have a design coupling area of 12-15 cm squared

  1. The crustal thickness of Australia

    Science.gov (United States)

    Clitheroe, G.; Gudmundsson, O.; Kennett, B.L.N.

    2000-01-01

    We investigate the crustal structure of the Australian continent using the temporary broadband stations of the Skippy and Kimba projects and permanent broadband stations. We isolate near-receiver information, in the form of crustal P-to-S conversions, using the receiver function technique. Stacked receiver functions are inverted for S velocity structure using a Genetic Algorithm approach to Receiver Function Inversion (GARFI). From the resulting velocity models we are able to determine the Moho depth and to classify the width of the crust-mantle transition for 65 broadband stations. Using these results and 51 independent estimates of crustal thickness from refraction and reflection profiles, we present a new, improved, map of Moho depth for the Australian continent. The thinnest crust (25 km) occurs in the Archean Yilgarn Craton in Western Australia; the thickest crust (61 km) occurs in Proterozoic central Australia. The average crustal thickness is 38.8 km (standard deviation 6.2 km). Interpolation error estimates are made using kriging and fall into the range 2.5-7.0 km. We find generally good agreement between the depth to the seismologically defined Moho and xenolith-derived estimates of crustal thickness beneath northeastern Australia. However, beneath the Lachlan Fold Belt the estimates are not in agreement, and it is possible that the two techniques are mapping differing parts of a broad Moho transition zone. The Archean cratons of Western Australia appear to have remained largely stable since cratonization, reflected in only slight variation of Moho depth. The largely Proterozoic center of Australia shows relatively thicker crust overall as well as major Moho offsets. We see evidence of the margin of the contact between the Precambrian craton and the Tasman Orogen, referred to as the Tasman Line. Copyright 2000 by the American Geophysical Union.

  2. Sensor for thickness measurement of a liquid metal film

    International Nuclear Information System (INIS)

    Blanc, R.

    1984-04-01

    Description, calibration and measuring method of a sensor for the measure of thin liquid metal depths in a temperature range of 0-500 0 C and for shift frequencies from 0 to 100 Hz; these sensors are based on the principle of induction-coil impedance variation, as a function of the thickness of an electrical conductor matter placed in the coil magnetic field [fr

  3. Thickness of the Buccal Plate in Posterior Teeth: A Prospective Cone Beam Computed Tomography Study.

    Science.gov (United States)

    Temple, Kayleigh Eaves; Schoolfield, John; Noujeim, Marcel E; Huynh-Ba, Guy; Lasho, David J; Mealey, Brian L

    Buccal plate thickness is an important clinical parameter for postextraction implant treatment planning. The purpose of this study was to assess buccal plate thickness of the posterior maxilla and mandible using cone beam computed tomography (CBCT). A total of 265 patients and 934 teeth met the inclusion criteria for this study. CBCT volumes were taken and aligned for measurement at the ideal midsagittal cross-section. Buccal plate thickness was measured at 1, 3, and 5 mm apical to the alveolar crest. The frequency of thick (≥ 1 mm), thin (teeth.

  4. Reflectance confocal microscopy features of thin versus thick melanomas.

    Science.gov (United States)

    Kardynal, Agnieszka; Olszewska, Małgorzata; de Carvalho, Nathalie; Walecka, Irena; Pellacani, Giovanni; Rudnicka, Lidia

    2018-01-24

    In vivo reflectance confocal microscopy (RCM) plays an increasingly important role in differential diagnosis of melanoma. The aim of the study was to assess typical confocal features of thin (≤1mm according to Breslow index) versus thick (>1mm) melanomas. 30 patients with histopathologically confirmed cutaneous melanoma were included in the study. Reflectance confocal microscopy was performed with Vivascope equipment prior to excision. Fifteen melanomas were thin (Breslow thickness ≤ 1mm) and 15 were thick melanomas (Breslow thickness >1mm). In the RCM examination, the following features were more frequently observed in thin compared to thick melanomas: edged papillae (26.7% vs 0%, p=0.032) and areas with honeycomb or cobblestone pattern (33.3% vs 6.7%, p=0.068). Both features are present in benign melanocytic lesions, so in melanoma are good prognostic factors. The group of thick melanomas compared to the group of thin melanomas in the RCM images presented with greater frequency of roundish cells (100% vs 40%, p=0.001), non-edged papillae (100% vs 60%, p=0.006), numerous pagetoid cells (73.3% vs 33.3%, p=0.028), numerous atypical cells at dermal-epidermal junction (53.3% vs 20%, p=0.058) and epidermal disarray (93.3% vs 66.7%, p=0.068). Non-invasive imaging methods helps in deepening of knowledge about the evolution and biology of melanoma. The most characteristic features for thin melanomas in confocal examination are: fragments of cobblestone or honeycomb pattern and edged papillae (as good prognostic factors). The features of thick melanomas in RCM examination are: roundish cells, non-edged papillae, numerous pagetoid cells at dermal-epidermal junction and epidermal disarray.

  5. Skin thickness as a potential marker of gestational age at birth despite different fetal growth profiles: A feasibility study.

    Directory of Open Access Journals (Sweden)

    Gabriela Luiza Nogueira Vitral

    Full Text Available New methodologies to estimate gestational age (GA at birth are demanded to face the limited access to obstetric ultrasonography and imprecision of postnatal scores. The study analyzed the correlation between neonatal skin thickness and pregnancy duration. Secondarily, it investigated the influence of fetal growth profiles on tissue layer dimensions.In a feasibility study, 222 infants selected at a term-to-preterm ratio of 1:1 were assessed. Reliable information on GA was based on the early ultrasonography-based reference. The thicknesses of the epidermal and dermal skin layers were examined using high-frequency ultrasonography. We scanned the skin over the forearm and foot plantar surface of the newborns. A multivariate regression model was adjusted to determine the correlation of GA with skin layer dimensions. The best model to correlate skin thickness with GA was fitted using the epidermal layer on the forearm site, adjusted to cofactors, as follows: Gestational age (weeks = -28.0 + 12.8 Ln (Thickness - 4.4 Incubator staying; R2 = 0.604 (P<0.001. In this model, the constant value for the standard of fetal growth was statistically null. The dermal layer thickness on the forearm and plantar surfaces had a negative moderate linear correlation with GA (R = -0.370, P<0.001 and R = -0.421, P<0.001, respectively. The univariate statistical analyses revealed the influence of underweight and overweight profiles on neonatal skin thickness at birth. Of the 222 infants, 53 (23.9% had inappropriate fetal growths expected for their GA. Epidermal thickness was not fetal growth standard dependent as follows: 172.2 (19.8 μm for adequate for GA, 171.4 (20.6 μm for SGA, and 177.7 (15.2 μm for LGA (P = 0.525, mean [SD] on the forearm.The analysis highlights a new opportunity to relate GA at birth to neonatal skin layer thickness. As this parameter was not influenced by the standard of fetal growth, skin maturity can contribute to clinical applications.

  6. Thickly Syndetical Sensitivity of Topological Dynamical System

    Directory of Open Access Journals (Sweden)

    Heng Liu

    2014-01-01

    Full Text Available Consider the surjective continuous map f:X→X, where X is a compact metric space. In this paper we give several stronger versions of sensitivity, such as thick sensitivity, syndetic sensitivity, thickly syndetic sensitivity, and strong sensitivity. We establish the following. (1 If (X,f is minimal and sensitive, then (X,f is syndetically sensitive. (2 Weak mixing implies thick sensitivity. (3 If (X,f is minimal and weakly mixing, then it is thickly syndetically sensitive. (4 If (X,f is a nonminimal M-system, then it is thickly syndetically sensitive. Devaney chaos implies thickly periodic sensitivity. (5 We give a syndetically sensitive system which is not thickly sensitive. (6 We give thickly syndetically sensitive examples but not cofinitely sensitive ones.

  7. three dimensional photoelastic investigations on thick rectangular

    African Journals Online (AJOL)

    user

    1983-09-01

    Sep 1, 1983 ... Thick rectangular plates are investigated by means of three-dimensional photoelasticity ... a thin plate theory and a higher order thick plate theory. 1. ..... number of fringes lest the accuracy of the results will be considerably.

  8. Autonomous Sea-Ice Thickness Survey

    Science.gov (United States)

    2016-06-01

    the conductivity of an infinitely thick slab of sea ice. Ice thickness, Hice, is then obtained by subtracting the height of the ...Thickness Survey of Sea Ice Runway” ERDC/CRREL SR-16-4 ii Abstract We conducted an autonomous survey of sea -ice thickness using the Polar rover Yeti...efficiency relative to manual surveys routinely con- ducted to assess the safety of roads and runways constructed on the sea ice. Yeti executed the

  9. doped ZnO thick film resistors

    Indian Academy of Sciences (India)

    The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ...

  10. Macular thickness and volume in the elderly

    DEFF Research Database (Denmark)

    Subhi, Yousif; Forshaw, Thomas; Sørensen, Torben Lykke

    2016-01-01

    manifests in the macula of the elderly focusing on clinical relevant measures that are thicknesses and volumes of different macular areas. Ageing seems to increase center point foveal thickness. Ageing does not seem to change the center subfield thickness significantly. Ageing decreases the inner and outer...

  11. Determination of material and its thickness for Cs-137 gamma source shielding

    International Nuclear Information System (INIS)

    Tukiman

    2008-01-01

    Its has been determined the shielding material and its thickness necessarily conducted due to every material will have different half-thickness characteristics, and by the selection a suitable material and its thickness will be obtained. Half-thickness of any material is the ability of the material at a certain thickness to absorb any radiation intensity so that the intensity becomes half of its source. Sample materials to be used are concrete, wood, and lead with their thickness varied. From experiment data and theoretical computation can be concluded that lead is the suitable material for shielding with the value of HVT for gamma radiation 0,732 cm. For wood and concrete will give half-thickness of 11,0 cm and 3,164 cm respectively. (author)

  12. Development of thick wall welding and cutting tools for ITER

    International Nuclear Information System (INIS)

    Nakahira, Masataka; Takahashi, Hiroyuki; Akou, Kentaro; Koizumi, Koichi

    1998-01-01

    The Vacuum Vessel, which is a core component of International Thermonuclear Experimental Reactor (ITER), is required to be exchanged remotely in a case of accident such as superconducting coil failure. The in-vessel components such as blanket and divertor are planned to be exchanged or fixed. In these exchange or maintenance operations, the thick wall welding and cutting are inevitable and remote handling tools are necessary. The thick wall welding and cutting tools for blanket are under developing in the ITER R and D program. The design requirement is to weld or cut the stainless steel of 70 mm thickness in the narrow space. Tungsten inert gas (TIG) arc welding, plasma cutting and iodine laser welding/cutting are selected as primary option. Element welding and cutting tests, design of small tools to satisfy space requirement, test fabrication and performance tests were performed. This paper reports the tool design and overview of welding and cutting tests. (author)

  13. Development of thick wall welding and cutting tools for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Nakahira, Masataka; Takahashi, Hiroyuki; Akou, Kentaro; Koizumi, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-04-01

    The Vacuum Vessel, which is a core component of International Thermonuclear Experimental Reactor (ITER), is required to be exchanged remotely in a case of accident such as superconducting coil failure. The in-vessel components such as blanket and divertor are planned to be exchanged or fixed. In these exchange or maintenance operations, the thick wall welding and cutting are inevitable and remote handling tools are necessary. The thick wall welding and cutting tools for blanket are under developing in the ITER R and D program. The design requirement is to weld or cut the stainless steel of 70 mm thickness in the narrow space. Tungsten inert gas (TIG) arc welding, plasma cutting and iodine laser welding/cutting are selected as primary option. Element welding and cutting tests, design of small tools to satisfy space requirement, test fabrication and performance tests were performed. This paper reports the tool design and overview of welding and cutting tests. (author)

  14. Extragalactic Peaked-spectrum Radio Sources at Low Frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Callingham, J. R.; Gaensler, B. M.; Sadler, E. M.; Lenc, E. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Ekers, R. D.; Bell, M. E. [CSIRO Astronomy and Space Science (CASS), Marsfield, NSW 2122 (Australia); Line, J. L. B.; Hancock, P. J.; Kapińska, A. D.; McKinley, B.; Procopio, P. [ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) (Australia); Hurley-Walker, N.; Tingay, S. J.; Franzen, T. M. O.; Morgan, J. [International Centre for Radio Astronomy Research (ICRAR), Curtin University, Bentley, WA 6102 (Australia); Dwarakanath, K. S. [Raman Research Institute (RRI), Bangalore 560080 (India); For, B.-Q. [International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, Crawley, WA 6009 (Australia); Hindson, L.; Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand); Offringa, A. R., E-mail: joseph.callingham@sydney.edu.au [Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo (Netherlands); and others

    2017-02-20

    We present a sample of 1483 sources that display spectral peaks between 72 MHz and 1.4 GHz, selected from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. The GLEAM survey is the widest fractional bandwidth all-sky survey to date, ideal for identifying peaked-spectrum sources at low radio frequencies. Our peaked-spectrum sources are the low-frequency analogs of gigahertz-peaked spectrum (GPS) and compact-steep spectrum (CSS) sources, which have been hypothesized to be the precursors to massive radio galaxies. Our sample more than doubles the number of known peaked-spectrum candidates, and 95% of our sample have a newly characterized spectral peak. We highlight that some GPS sources peaking above 5 GHz have had multiple epochs of nuclear activity, and we demonstrate the possibility of identifying high-redshift ( z > 2) galaxies via steep optically thin spectral indices and low observed peak frequencies. The distribution of the optically thick spectral indices of our sample is consistent with past GPS/CSS samples but with a large dispersion, suggesting that the spectral peak is a product of an inhomogeneous environment that is individualistic. We find no dependence of observed peak frequency with redshift, consistent with the peaked-spectrum sample comprising both local CSS sources and high-redshift GPS sources. The 5 GHz luminosity distribution lacks the brightest GPS and CSS sources of previous samples, implying that a convolution of source evolution and redshift influences the type of peaked-spectrum sources identified below 1 GHz. Finally, we discuss sources with optically thick spectral indices that exceed the synchrotron self-absorption limit.

  15. Factors influencing endometrial thickness in postmenopausal women.

    Science.gov (United States)

    Hebbar, S; Chaya, V; Rai, L; Ramachandran, A

    2014-07-01

    Cut-off values for endometrial thickness (ET) in asymptomatic postmenopausal woman have been standardized. However, there are no comprehensive studies to document how various factors can influence the ET after the age of menopause. To study the various factors influencing the ET in postmenopausal women. This was a prospective observational study. A total of 110 postmenopausal women underwent detailed history taking, clinical examination, and transvaginal scan for uterine volume and ovarian volume. The volumes were calculated by using ellipsoid formula: Width × thickness × height × 0.523. The variation in ET with respect to the influencing factors such as age, duration of menopause, parity, body mass index (BMI), medical illness like diabetes/hypertension, drugs like tamoxifen, presence of myoma, uterine volume, ovarian volume, and serum estradiol (in selected patients) were measured. Descriptive analysis was performed using SPSS software (version 16, Chicago II, USA) to obtain mean, standard deviation (SD), 95% confidence intervals (CIs) and inter quartile ranges. Comparison of means was carried out using analysis of variance. The mean (SD) age of the patients was 55.4 (6.91) years (95% CI, 54.1, 56.7). The mean (SD) age at menopause was 47.95 (3.90) years (95% CI, 47.2, 48.7) and the mean (SD) duration of menopause was 7.27 (6.65) years (95% CI, 6.01, 8.53). The mean (SD) ET was 3.8 (2.3) mm (95% CI, 3.36, 4.23). Medical illness like diabetes and hypertension did not alter the ET. ET increased as BMI increased and it was statistically significant. The presence of myoma increased uterine volume significantly and was associated with thick endometrial stripe. Similarly, whenever the ovaries were visualized and as the ovarian volume increased, there was an increase in ET. When ET was > 4 mm (n = 37), they were offered endocel, of which 16 agreed to undergo the procedure. None were found to have endometrial cancer. This study suggests that parity, BMI, presence of

  16. The effects of slice thickness and reconstructive parameters on VR image quality in multi-slice CT

    International Nuclear Information System (INIS)

    Gao Zhenlong; Wang Qiang; Liu Caixia

    2005-01-01

    Objective: To explore the effects of slice thickness, reconstructive thickness and reconstructive interval on VR image quality in multi-slice CT, in order to select the best slice thickness and reconstructive parameters for the imaging. Methods: Multi-slice CT scan was applied on a rubber dinosaur model with different slice thickness. VR images were reconstructed with different reconstructive thickness and reconstructive interval. Five radiologists were invited to evaluate the quality of the images without knowing anything about the parameters. Results: The slice thickness, reconstructive thickness and reconstructive interval did have effects on VR image quality and the effective degree was different. The effective coefficients were V 1 =1413.033, V 2 =563.733, V 3 =390.533, respectively. The parameters interacted with the others (P<0.05). The smaller of those parameters, the better of the image quality. With a small slice thickness and a reconstructive slice equal to slice thickness, the image quality had no obvious difference when the reconstructive interval was 1/2, 1/3, 1/4 of the slice thickness. Conclusion: A relative small scan slice thickness, a reconstructive slice equal to slice thickness and a reconstructive interval 1/2 of the slice thickness should be selected for the best VR image quality. The image quality depends mostly on the slice thickness. (authors)

  17. De Novo Assembly of Complete Chloroplast Genomes from Non-model Species Based on a K-mer Frequency-Based Selection of Chloroplast Reads from Total DNA Sequences

    Directory of Open Access Journals (Sweden)

    Shairul Izan

    2017-08-01

    Full Text Available Whole Genome Shotgun (WGS sequences of plant species often contain an abundance of reads that are derived from the chloroplast genome. Up to now these reads have generally been identified and assembled into chloroplast genomes based on homology to chloroplasts from related species. This re-sequencing approach may select against structural differences between the genomes especially in non-model species for which no close relatives have been sequenced before. The alternative approach is to de novo assemble the chloroplast genome from total genomic DNA sequences. In this study, we used k-mer frequency tables to identify and extract the chloroplast reads from the WGS reads and assemble these using a highly integrated and automated custom pipeline. Our strategy includes steps aimed at optimizing assemblies and filling gaps which are left due to coverage variation in the WGS dataset. We have successfully de novo assembled three complete chloroplast genomes from plant species with a range of nuclear genome sizes to demonstrate the universality of our approach: Solanum lycopersicum (0.9 Gb, Aegilops tauschii (4 Gb and Paphiopedilum henryanum (25 Gb. We also highlight the need to optimize the choice of k and the amount of data used. This new and cost-effective method for de novo short read assembly will facilitate the study of complete chloroplast genomes with more accurate analyses and inferences, especially in non-model plant genomes.

  18. Hg(+) Frequency Standards

    Science.gov (United States)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

  19. Enamel thickness after preparation of tooth for porcelain laminate.

    Science.gov (United States)

    Pahlevan, Ayoub; Mirzaee, Mansoreh; Yassine, Esmaeil; Ranjbar Omrany, Ladan; Hasani Tabatabaee, Masumeh; Kermanshah, Hamid; Arami, Sakineh; Abbasi, Mehdy

    2014-07-01

    In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers. Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope. Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05). The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.

  20. Enamel thickness after preparation of tooth for porcelain laminate.

    Directory of Open Access Journals (Sweden)

    Ayoub Pahlevan

    2014-08-01

    Full Text Available In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers.Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope.Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05.The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.

  1. Intelligent processing for thick composites

    Science.gov (United States)

    Shin, Daniel Dong-Ok

    2000-10-01

    Manufacturing thick composite parts are associated with adverse curing conditions such as large in-plane temperature gradient and exotherms. The condition is further aggravated because the manufacturer's cycle and the existing cure control systems do not adequately counter such affects. In response, the forecast-based thermal control system is developed to have better cure control for thick composites. Accurate cure kinetic model is crucial for correctly identifying the amount of heat generated for composite process simulation. A new technique for identifying cure parameters for Hercules AS4/3502 prepreg is presented by normalizing the DSC data. The cure kinetics is based on an autocatalytic model for the proposed method, which uses dynamic and isothermal DSC data to determine its parameters. Existing models are also used to determine kinetic parameters but rendered inadequate because of the material's temperature dependent final degree of cure. The model predictions determined from the new technique showed good agreement to both isothermal and dynamic DSC data. The final degree of cure was also in good agreement with experimental data. A realistic cure simulation model including bleeder ply analysis and compaction is validated with Hercules AS4/3501-6 based laminates. The nonsymmetrical temperature distribution resulting from the presence of bleeder plies agreed well to the model prediction. Some of the discrepancies in the predicted compaction behavior were attributed to inaccurate viscosity and permeability models. The temperature prediction was quite good for the 3cm laminate. The validated process simulation model along with cure kinetics model for AS4/3502 prepreg were integrated into the thermal control system. The 3cm Hercules AS4/3501-6 and AS4/3502 laminate were fabricated. The resulting cure cycles satisfied all imposed requirements by minimizing exotherms and temperature gradient. Although the duration of the cure cycles increased, such phenomena was

  2. Thin dielectric film thickness determination by advanced transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, A.C.; Foran, B.; Kisielowski, C.; Muller, D.; Pennycook, S.; Principe, E.; Stemmer, S.

    2003-09-01

    High Resolution Transmission Electron Microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by non-specialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods was steadily improved reaching now into the sub Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this paper, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this paper is the proposal of a reproducible method for film thickness determination.

  3. Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding

    International Nuclear Information System (INIS)

    Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan

    2013-01-01

    We have explored here a hollow cylindrical laser plasma multifilament waveguide with discontinuous finite thickness cladding, in which the separation between individual filaments is in the range of several millimeters and the waveguide cladding thickness is in the order of the microwave penetration depth. Such parameters give a closer representation of a realistic laser filament waveguide sustained by a long stable propagation of femtosecond (fs) laser pulses. We report how the waveguide losses depend on structural parameters like normalized plasma filament spacing, filament to filament distance or pitch, normal spatial frequency, and radius of the plasma filament. We found that for typical plasma parameters, the proposed waveguide can support guided modes of microwaves in extremely high frequency even with a cladding consisting of only one ring of plasma filaments. The loss of the microwave radiation is mainly caused by tunneling through the discontinuous finite cladding, i.e., confinement loss, and is weakly dependent on the plasma absorption. In addition, the analysis indicates that the propagation loss is fairly large compared with the loss of a plasma waveguide with a continuous infinite thickness cladding, while they are comparable when using a cladding contains more than one ring. Compared to free space propagation, this waveguide still presents a superior microwave transmission to some distance in the order of the filamentation length; thus, the laser plasma filaments waveguide may be a potential channel for transporting pulsed-modulated microwaves if ensuring a long and stable propagation of fs laser pulses.

  4. Inlfuence of Different-Frequency Glucocorticoid Induction on Morphological Structures of Humeri, Soft Tissues and Immune System in Rats

    Institute of Scientific and Technical Information of China (English)

    LI Jian-min; LI Heng

    2016-01-01

    Objective: To explore the influence of different-frequency glucocorticoid (GC) induction on morphological structures of humeri and soft tissues as well as immune system in rats. Methods: A total of 32 speciifc pathogen-free (SPF) SD rats at the age of 3 months were selected and randomly divided into 4 groups, 8 cases in each group. The rats in control group were not given any treatment, while those in low-, moderate- and high-frequency groups were treated with intramuscular injection of dexamethasone 1 mg/kg per time for twice, 4 times and 6 times per week, respectively. All the rats were sacriifced on d30 to measure their body mass and qualities of soft tissues and immune organs, and bone histomorphometry was applied to analyze humeral bone mass and bone structural changes. Results: Compared with control group, there was no change in cancellous bone mass and bone structures of upper humeri in low-frequency group, but serious loss of bone mass, signiifcantly degenerated bone structure, markedly reduced trabecular thickness and number as well as notably increased trabecular separation was all observed in moderate- and high-frequency groups. The size of cortical bones, total size of bone structure, thickness of cortical bones and size percentage of cortical bones in middle humeri reduced apparently, while the size percentage of medullary cavity increased dramatically in high-frequency group. Growth plate thickness of upper humeri decreased in low-, moderate- and high-frequency groups, and the diameters of mastocytes diminished in moderate- and high-frequency groups. Compared with control group, body mass decreased obviously, qualities and indexes of spleen and thymus showed decreasing tendency along with the increase of drug administration frequency in low-, moderate- and high-frequency groups. Conclusion: Low-frequency GC cannot change humeral morphology. The higher the frequency of drug administration is, the more the loss of cancellous bone mass is. When the

  5. Giant moving vortex mass in thick magnetic nanodots.

    Science.gov (United States)

    Guslienko, K Y; Kakazei, G N; Ding, J; Liu, X M; Adeyeye, A O

    2015-09-10

    Magnetic vortex is one of the simplest topologically non-trivial textures in condensed matter physics. It is the ground state of submicron magnetic elements (dots) of different shapes: cylindrical, square etc. So far, the vast majority of the vortex dynamics studies were focused on thin dots with thickness 5-50 nm and only uniform across the thickness vortex excitation modes were observed. Here we explore the fundamental vortex mode in relatively thick (50-100 nm) dots using broadband ferromagnetic resonance and show that dimensionality increase leads to qualitatively new excitation spectra. We demonstrate that the fundamental mode frequency cannot be explained without introducing a giant vortex mass, which is a result of the vortex distortion due to interaction with spin waves. The vortex mass depends on the system geometry and is non-local because of important role of the dipolar interaction. The mass is rather small for thin dots. However, its importance increases drastically with the dot thickness increasing.

  6. Study on the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration

    International Nuclear Information System (INIS)

    Lin Shuyu; Tian Hua

    2008-01-01

    A sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is studied. The transducer consists of front and back metal masses, and coaxially segmented, thickness polarized piezoelectric ceramic thin rings. For this kind of sandwich piezoelectric transducers in thickness vibration, it is required that the lateral dimension of the transducer is sufficiently large compared with its longitudinal dimension so that no lateral displacements in the transducer can occur (laterally clamped). In this paper, the thickness vibration of the piezoelectric ceramic stack consisting of a number of identical piezoelectric ceramic thin rings is analysed and its electro-mechanical equivalent circuit is obtained. The resonance frequency equation for the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is derived. Based on the frequency equation, two sandwich piezoelectric ceramic ultrasonic transducers are designed and manufactured, and their resonance frequencies are measured. It is shown that the measured resonance frequencies are in good agreement with the theoretical results. This kind of sandwich piezoelectric ultrasonic transducer is expected to be used in megasonic ultrasonic cleaning and sonochemistry where high power and high frequency ultrasound is needed

  7. Method of working thick beds

    Energy Technology Data Exchange (ETDEWEB)

    Giezynski, A; Bialasik, A; Krawiec, A; Wylenzek, A

    1981-12-30

    The patented method of working thick coal beds in layers consists of creating in the collapsed rocks or from the fill material a bearing rock plate by strengthening these rocks with a hardening composition made of wastes of raw material, resin and water injected into the rock through wells. The difference in the suggestion is that through boreholes drilled in the lower part of the rock roofing on a previously calculated network, a solution is regularly injected which consists of dust wastes obtained in electric filters during production of clinker from mineral raw material in a quantity of 60-70% by volume, wastes of open-hearth production in a quantity of 15-20% and natural sand in a quantity of 15-20%, and water in a quantity of 35-55% of the volume of mineral components. In the second variant, the injected compostion contains: wastes from production of clinker 55-57%, open-hearth wastes 20-23%, natural sand 12-14%, asbestos fine particles 7-8% and water 38-45% of the volume of mineral components. In addition, the difference is that in the boreholes drilled in the coal block directly under the roofing, a composition is injected which consists of natural sand and catalyst in the form of powder and individually supplied liquid synthetic resin in a quantity of 3-5% by weight in relation to the sand. The hardening time with normal temperature is 1-1.5 h, after which strength is reached of 80 kg-f/cm/sup 2/.

  8. Estimation of dosimetry parameters for an EB accelerator using graphite calorimeters of different thickness

    International Nuclear Information System (INIS)

    Benny, P.G.; Khader, S.A.; Sarma, K.S.S.

    2012-01-01

    Graphite calorimeters of different thickness in the range of 0.6 mm to 10 mm have been designed and fabricated for the dosimetry of 2 MeV electron beam accelerator. Average absorbed dose in each of the calorimeters of different thickness has been determined. The paper reports a method for selecting calorimeters with suitable thickness for its application as absorbed dose calorimeters and as total energy absorption calorimeters for an electron beam of particular energy. Also it reports, using calorimeters of different thickness, it is possible to estimate various parameters such as energy fluence, average absorbed dose, absorbed dose at any depth in the medium and practical range.

  9. Manufacturing of composite parts reinforced through-thickness by tufting

    OpenAIRE

    Dell'Anno, G.; Treiber, J. W G; Partridge, Ivana K

    2016-01-01

    The paper aims at providing practical guidelines for the manufacture of composite parts reinforced by tufting. The need for through-thickness reinforcement of high performance carbon fibre composite structures is reviewed and various options are presented. The tufting process is described in detail and relevant aspects of the technology are analysed such as: equipment configuration and setup, latest advances in tooling, thread selection, preform supporting systems and choice of ancillary mate...

  10. Characteristics of the thick, compound refractive lens

    International Nuclear Information System (INIS)

    Pantell, Richard H.; Feinstein, Joseph; Beguiristain, H. Raul; Piestrup, Melvin A.; Gary, Charles K.; Cremer, Jay T.

    2003-01-01

    A compound refractive lens (CRL), consisting of a series of N closely spaced lens elements each of which contributes a small fraction of the total focusing, can be used to focus x rays or neutrons. The thickness of a CRL can be comparable to its focal length, whereupon a thick-lens analysis must be performed. In contrast with the conventional optical lens, where the ray inside the lens follows a straight line, the ray inside the CRL is continually changing direction because of the multiple refracting surfaces. Thus the matrix representation for the thick CRL is quite different from that for the thick optical lens. Principal planes can be defined such that the thick-lens matrix can be converted to that of a thin lens. For a thick lens the focal length is greater than for a thin lens with the same lens curvature, but this lengthening effect is less for the CRL than for the conventional optical lens

  11. Laser Processing on the Surface of Niobium Superconducting Radio-Frequency Accelerator Cavities

    Science.gov (United States)

    Singaravelu, Senthilraja; Klopf, Michael; Krafft, Geoffrey; Kelley, Michael

    2011-03-01

    Superconducting Radio frequency (SRF) niobium cavities are at the heart of an increasing number of particle accelerators.~ Their performance is dominated by a several nm thick layer at the interior surface. ~Maximizing its smoothness is found to be critical and aggressive chemical treatments are employed to this end.~ We describe laser-induced surface melting as an alternative ``greener'' approach.~ Modeling guided selection of parameters for irradiation with a Q-switched Nd:YAG laser.~ The resulting topography was examined by SEM, AFM and Stylus Profilometry.

  12. Graph Treewidth and Geometric Thickness Parameters

    OpenAIRE

    Dujmović, Vida; Wood, David R.

    2005-01-01

    Consider a drawing of a graph $G$ in the plane such that crossing edges are coloured differently. The minimum number of colours, taken over all drawings of $G$, is the classical graph parameter "thickness". By restricting the edges to be straight, we obtain the "geometric thickness". By further restricting the vertices to be in convex position, we obtain the "book thickness". This paper studies the relationship between these parameters and treewidth. Our first main result states that for grap...

  13. Localizing gravity on exotic thick 3-branes

    International Nuclear Information System (INIS)

    Castillo-Felisola, Oscar; Melfo, Alejandra; Pantoja, Nelson; Ramirez, Alba

    2004-01-01

    We consider localization of gravity on thick branes with a nontrivial structure. Double walls that generalize the thick Randall-Sundrum solution, and asymmetric walls that arise from a Z 2 symmetric scalar potential, are considered. We present a new asymmetric solution: a thick brane interpolating between two AdS 5 spacetimes with different cosmological constants, which can be derived from a 'fake supergravity' superpotential, and show that it is possible to confine gravity on such branes

  14. Does cement mantle thickness really matter?

    OpenAIRE

    Caruana, J.

    2008-01-01

    The thickness of the cement mantle around the femoral component of total hip replacements is a contributing factor to aseptic loosening and revision. Nevertheless, various designs of stems and surgical tooling lead to cement mantles of differing thicknesses. This thesis is concerned with variability in cement thickness around the Stanmore Hip, due to surgical approach, broach size and stem orientation, and its effects on stress and cracking in the cement. The extent to which cement mantle thi...

  15. Radiation transmission pipe thickness measurement system

    International Nuclear Information System (INIS)

    Higashi, Yasuhiko

    2010-01-01

    Fuji Electric Systems can be measured from the outer insulation of the transmission Characteristics and radiation detection equipment had been developed that can measure pipe wall thinning in plant and running, the recruitment of another three-beam calculation method by pipe thickness measurement system was developed to measure the thickness of the pipe side. This equipment has been possible to measure the thickness of the circumferential profile of the pipe attachment by adopting automatic rotation. (author)

  16. Hydroxyapatite screen-printed thick films: optical and electrical properties

    International Nuclear Information System (INIS)

    Silva, C.C.; Rocha, H.H.B.; Freire, F.N.A.; Santos, M.R.P.; Saboia, K.D.A.; Goes, J.C.; Sombra, A.S.B.

    2005-01-01

    In this paper, we did a study on the structural and electrical properties of bioceramic hydroxiapatite (HA) thick films. The films were prepared in two layers using the screen-printing technique on Al 2 O 3 substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite to be used in the films. We also look for the effect of the grain size of the HA in the final properties of the film. The samples were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), infrared and Raman scattering spectroscopy and electrical measurements. We did a study of the dielectric permittivity and the loss of the films in the radio-frequency of the spectra. The X-ray diffraction patterns of the films indicate that all the peaks associated to HA phase is present in the films. One can notice that, for all the films there is a decrease of the DC (dielectric constant) with the increase of the frequency. The values of the dielectric constant of the films are in between 4 and 9 (at 1 kHz), as a function of the flux concentration. The loss is decreasing as we increase the frequency for all the films. These results strongly suggest that the screen-printing HA thick films are good candidates for applications in biocompatible coatings of implant materials

  17. Hydroxyapatite screen-printed thick films: optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Silva, C.C. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Rocha, H.H.B. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Freire, F.N.A. [Departamento de Quimica Orga-circumflex nica e Inorga-circumflex nica-UFC, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil); Santos, M.R.P. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Saboia, K.D.A. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Goes, J.C. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Sombra, A.S.B. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil)]. E-mail: sombra@fisica.ufc.br

    2005-07-15

    In this paper, we did a study on the structural and electrical properties of bioceramic hydroxiapatite (HA) thick films. The films were prepared in two layers using the screen-printing technique on Al{sub 2}O{sub 3} substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite to be used in the films. We also look for the effect of the grain size of the HA in the final properties of the film. The samples were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), infrared and Raman scattering spectroscopy and electrical measurements. We did a study of the dielectric permittivity and the loss of the films in the radio-frequency of the spectra. The X-ray diffraction patterns of the films indicate that all the peaks associated to HA phase is present in the films. One can notice that, for all the films there is a decrease of the DC (dielectric constant) with the increase of the frequency. The values of the dielectric constant of the films are in between 4 and 9 (at 1 kHz), as a function of the flux concentration. The loss is decreasing as we increase the frequency for all the films. These results strongly suggest that the screen-printing HA thick films are good candidates for applications in biocompatible coatings of implant materials.

  18. Asymmetric transmission of acoustic waves in a layer thickness distribution gradient structure using metamaterials

    Directory of Open Access Journals (Sweden)

    Jung-San Chen

    2016-09-01

    Full Text Available This research presents an innovative asymmetric transmission design using alternate layers of water and metamaterial with complex mass density. The directional transmission behavior of acoustic waves is observed numerically inside the composite structure with gradient layer thickness distribution and the rectifying performance of the present design is evaluated. The layer thickness distributions with arithmetic and geometric gradients are considered and the effect of gradient thickness on asymmetric wave propagation is systematically investigated using finite element simulation. The numerical results indicate that the maximum pressure density and transmission through the proposed structure are significantly influenced by the wave propagation direction over a wide range of audible frequencies. Tailoring the thickness of the layered structure enables the manipulation of asymmetric wave propagation within the desired frequency range. In conclusion, the proposed design offers a new possibility for developing directional-dependent acoustic devices.

  19. Dual beam x-ray thickness gauge

    International Nuclear Information System (INIS)

    Allport, J.J.

    1977-01-01

    The apparatus and method for continuous measurement of thickness of a sheet at a rolling mill or the like without contacting the sheet are described. A system directing radiation through the sheet in two energy bands and providing a measure of change in composition of the material as it passes the thickness gauging station is included. A system providing for changing the absorption coefficient of the material in the thickness measurement as a function of the change in composition so that the measured thickness is substantially independent of variations in composition is described

  20. Uncertainties in thick-target PIXE analysis

    International Nuclear Information System (INIS)

    Campbell, J.L.; Cookson, J.A.; Paul, H.

    1983-01-01

    Thick-target PIXE analysis insolves uncertainties arising from the calculation of thick-target X-ray production in addition to the usual PIXE uncertainties. The calculation demands knowledge of ionization cross-sections, stopping powers and photon attenuation coefficients. Information on these is reviewed critically and a computational method is used to estimate the uncertainties transmitted from this data base into results of thick-target PIXE analyses with reference to particular specimen types using beams of 2-3 MeV protons. A detailed assessment of the accuracy of thick-target PIXE is presented. (orig.)

  1. Comparison of Simulated PEC Probe Performance for Detecting Wall Thickness Reduction

    International Nuclear Information System (INIS)

    Shin, Young Kil; Choi, Dong Myung; Jung, Hee Sung

    2009-01-01

    In this paper, four different types of pulsed eddy current(PEC) probe are designed and their performance of detecting wall thickness reduction is compared. By using the backward difference method in time and the finite element method in space, PEC signals from various thickness and materials are numerically calculated and three features of the signal are selected. Since PEC signals and features are obtained by various types and sizes of probe, the comparison is made through the normalized features which reflect the sensitivity of the feature to thickness reduction. The normalized features indicate that the shielded reflection probe provides the best sensitivity to wall thickness reduction for all three signal features. Results show that the best sensitivity to thickness reduction can be achieved by the peak value, but also suggest that the time to peak can be a good candidate because of its linear relationship with the thickness variation.

  2. Asymmetric vibrations of shells of revolution having meridionally varying curvature and thickness

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Miura, Kazuyuki.

    1988-01-01

    An exact method using power series expansions is presented for solving asymmetric free vibration problems for shells of revolution having meridionally varying curvature and thickness. The gaverning equations of motion and the boundary conditions are derived from the stationary conditions of the Lagrangian of the shells of revolution. The method is demonstrated for shells of revolution having elliptical, cycloidal, parabolical, catenary and hyperbolical meridional curvature. The natural frequencies are numerically calculated for these shells having second degree thickness variation. (author)

  3. Experimental study of the polymer powder film thickness uniformity produced by the corona discharge

    Science.gov (United States)

    Fazlyyyakhmatov, Marsel

    2017-01-01

    The results of an experimental study of the polymer powder film thickness uniformity are presented. Polymer powder films are produced by the electrostatic field of corona discharge. Epoxy and epoxy-polyester powder films with thickness in the range of 30-120 microns are studied. Experimentally confirmed possibility of using these coatings as protective matching layer of piezoceramic transducers at frequencies of 0.5-15 MHz.

  4. Magnetic moment investigation by frequency mixing techniques.

    Science.gov (United States)

    Teliban, I; Thede, C; Chemnitz, S; Bechtold, C; Quadakkers, W J; Schütze, M; Quandt, E

    2009-11-01

    Gas turbines and other large industrial equipment are subjected to high-temperature oxidation and corrosion. Research and development of efficient protective coatings is the main task in the field. Also, knowledge about the depletion state of the coating during the operation time is important. To date, practical nondestructive methods for the measurement of the depletion state do not exist. By integrating magnetic phases into the coating, the condition of the coating can be determined by measuring its magnetic properties. In this paper, a new technique using frequency mixing is proposed to investigate the thickness of the coatings based on their magnetic properties. A sensor system is designed and tested on specific magnetic coatings. New approaches are proposed to overcome the dependency of the measurement on the distance between coil and sample that all noncontact techniques face. The novelty is a low cost sensor with high sensibility and selectivity which can provide very high signal-to-noise ratios. Prospects and limitations are discussed for future use of the sensor in industrial applications.

  5. Reliability assessment for thickness measurements of pipe wall using probability of detection

    International Nuclear Information System (INIS)

    Nakamoto, Hiroyuki; Kojima, Fumio; Kato, Sho

    2013-01-01

    This paper proposes a reliability assessment method for thickness measurements of pipe wall using probability of detection (POD). Thicknesses of pipes are measured by qualified inspectors with ultrasonic thickness gauges. The inspection results are affected by human factors of the inspectors and include some errors, because the inspectors have different experiences and frequency of inspections. In order to ensure reliability for inspection results, first, POD evaluates experimental results of pipe-wall thickness inspection. We verify that the results have differences depending on inspectors including qualified inspectors. Second, two human factors that affect POD are indicated. Finally, it is confirmed that POD can identify the human factors and ensure reliability for pipe-wall thickness inspections. (author)

  6. Magnetic properties of permalloy films with different thicknesses deposited onto obliquely sputtered Cu underlayers

    International Nuclear Information System (INIS)

    Li, Xiaoyu; Sun, Xiaojun; Wang, Jianbo; Liu, Qingfang

    2015-01-01

    In this work, the influence of obliquely sputtered Cu underlayer of 10 nm on the magnetic properties of normally sputtered Permalloy thin films with different thicknesses from 10 nm to 150 nm has been investigated. It has been found that the samples with the Permalloy layer thickness ranging from 10 nm to 70 nm exhibit a good in-plane uniaxial magnetic anisotropy, and the increase of the film thickness leads to a decrease of the anisotropy field and the natural resonance frequency. The critical Permalloy layer thickness for stripe domain initiation of these films is about 80 nm, which is thinner than that of obliquely sputtered Permalloy thin films without an underlayer. The characteristic shapes of hysteresis loops which can be called ''transcritical'' are observed above the critical thickness. The condition and mechanism of appearing stripe domain structure were discussed and it has been found that the frequency response of permeability of the anisotropic films shows the characteristics of multi-peak resonance. - Highlights: • Py films were fabricated on obliquely sputtered Cu underlayers by RF magnetron sputtering. • Effects of Py layer thickness on anisotropy, ferromagnetic resonance frequency have been studied. • Samples with Py layer (<70 nm) show a good in-plane uniaxial magnetic anisotropy. • Samples with Py layer (>80 nm) show stripe domains and multi-peaks in permeability spectra

  7. Low-frequency-noise complaints

    DEFF Research Database (Denmark)

    Pedersen, Christian Sejer; Møller, Henrik; Persson-Waye, Kerstin

    2008-01-01

    From 203 cases of low-frequency complaints a random selection of twenty-one cases were investigated. The main aim of the investigation was to answer the question whether the annoyance is caused by an external physical sound or by a physically non-existing sound, i.e. low-frequency tinnitus. Noise...... of the complainants are annoyed by a physical sound (20-180 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40-100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance - or at all audible - in any of the investigated cases, and none...... of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases....

  8. High-performance piezoelectric thick film based energy harvesting micro-generators for MEMS

    DEFF Research Database (Denmark)

    Zawada, Tomasz; Hansen, Karsten; Lou-Moeller, Rasmus

    2010-01-01

    and are transformed by the energy harvesting micro-generator into usable electrical signal. The micro-generator comprises a silicon cantilever with integrated InSensor® TF2100 PZT thick film deposited using screen-printing. The output power versus frequency and electrical load has been investigated. Furthermore......, devices based on modified, pressure treated thick film materials have been tested and compared with the commercial InSensor® TF2100 PZT thick films. It has been found that the structures based on the pressure treated materials exhibit superior properties in terms of energy output....

  9. Asymmetric vibrations of thick shells of revolution having meridionally varying curvature

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Yachita, Takumi.

    1988-01-01

    An exact method using power series expansions is presented for solving asymmetric free vibration problems for thick shells of revolution having meridionally varying curvature. Based on the improved thick shell theory, the Lagrangian of the shells of revolution are obtained, and the equations of motion and the boundary conditions are derived from the stationary condition of the Lagrangian. The method is demonstrated for thick shells of revolution having elliptical, cycloidal, parabolical, catenary and hyperbolical meridional curvature. The results by the present method are compared with those by the thin shell theory and the effects of the rotatory inertia and the shear deformation upon the natural frequencies are clarified. (author)

  10. Axisymmetric vibrations of thick shells of revolution having meridionally varying curvature

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin; Takahashi, Fumiaki.

    1987-01-01

    An exact method using power series expansions is presented for solving axisymmetric free vibration problems for thick shells of revolution having meridionally varying curvature. Based on the improved thick shell theory, the Lagrangian of the shells of revolution are obtained, and the equations of motion and the boundary conditions are derived from the stationary condition of the Lagrangian. The method is applied to thick shells of revolution having their generating curves of ellipse, cycloid, parabola, catenary and hyperbola. The results by the present method are compared with those by the thin shell theory and the effects of rotatory inertia and shear deformation upon the natural frequencies and the mode shapes are clarified. (author)

  11. Contribution to the study of slab thickness

    International Nuclear Information System (INIS)

    Moraitis, G.A.; Rorris, G.P.

    1978-01-01

    A method is proposed for calculating the time-independent values of the equivalent slab thickness of the ionosphere, defined as the ratio of the total electron content to the corresponding maximum electron density of the F region. Periodic variations of slab thickness are studied and are correlated to relative changes in exospheric temperature, deduced from the OGO-6 model

  12. Eggshell thickness in mourning dove populations

    Science.gov (United States)

    Kreitzer, J.F.

    1971-01-01

    Eggs (n = 452) of the mourning dove (Zenaidura macroura) were collected from 9 states in 1969 and 11 states in 1970, and shell thickness was compared with that of eggs (n = 97) collected from 24 states during the years 1861 to 1935. Mean shell thickness did not differ significantly in the test groups.

  13. Applications of precision ultrasonic thickness gauging

    International Nuclear Information System (INIS)

    Fowler, K.A.; Elfbaum, G.M.; Husarek, V.; Castel, J.G.

    1976-01-01

    Pulse-echo ultrasonic thickness gauging is now recognized as an accurate method of measuring thickness of a product from one side when the velocity of ultrasound in the material is known. The advantages and present limitation of this gauging technique are presented, together with several applications of industrial interest [fr

  14. Skull thickness in patients with clefts

    DEFF Research Database (Denmark)

    Arntsen, T; Kjaer, I; Sonnesen, L

    2010-01-01

    The purpose was to analyze skull thickness in incomplete cleft lip (CL), cleft palate (CP), and combined cleft lip and palate (UCLP).......The purpose was to analyze skull thickness in incomplete cleft lip (CL), cleft palate (CP), and combined cleft lip and palate (UCLP)....

  15. Magma Supply of Southwest Indian Ocean: Implication from Crustal Thickness Anomalies

    Science.gov (United States)

    Chiheng, L.; Jianghai, L.; Huatian, Z.; Qingkai, F.

    2017-12-01

    The Southwest Indian Ridge (SWIR) is one of the world's slowest spreading ridges with a full spreading rate of 14mm a-1, belonging to ultraslow spreading ridge, which are a novel class of spreading centers symbolized by non-uniform magma supply and crustal accretion. Therefore, the crustal thickness of Southwest Indian Ocean is a way to explore the magmatic and tectonic process of SWIR and the hotspots around it. Our paper uses Residual Mantle Bouguer Anomaly processed with the latest global public data to invert the relative crustal thickness and correct it according to seismic achievements. Gravity-derived crustal thickness model reveals a huge range of crustal thickness in Southwest Indian Ocean from 0.04km to 24km, 7.5km of average crustal thickness, and 3.5km of standard deviation. In addition, statistics data of crustal thickness reveal the frequency has a bimodal mixed skewed distribution, which indicates the crustal accretion by ridge and ridge-plume interaction. Base on the crustal thickness model, we divide three types of crustal thickness in Southwest Indian Ocean. About 20.31% of oceanic crust is 9.8km thick as thick crust. Furthermore, Prominent thin crust anomalies are associated with the trend of most transform faults, but thick crust anomalies presents to northeast of Andrew Bain transform fault. Cold and depleted mantle are also the key factors to form the thin crust. The thick crust anomalies are constrained by hotspots, which provide abundant heat to the mantle beneath mid-ocean ridge or ocean basin. Finally, we roughly delineate the range of ridge-plume interaction and transform fault effect.

  16. MUC1 gene polymorphism in three Nelore lines selected for growth and its association with growth and carcass traits.

    Science.gov (United States)

    de Souza, Fabio Ricardo Pablos; Maione, Sandra; Sartore, Stefano; Soglia, Dominga; Spalenza, Veronica; Cauvin, Elsa; Martelli, Lucia Regina; Mercadante, Maria Eugênia Zerlotti; Sacchi, Paola; de Albuquerque, Lucia Galvão; Rasero, Roberto

    2012-02-01

    The objective of this study was to describe the VNTR polymorphism of the mucin 1 gene (MUC1) in three Nelore lines selected for yearling weight to determine whether allele and genotype frequencies of this polymorphism were affected by selection for growth. In addition, the effects of the polymorphism on growth and carcass traits were evaluated. Birth, weaning and yearling weights, rump height, Longissimus muscle area, backfat thickness, and rump fat thickness, were analyzed. A total of 295 Nelore heifers from the Beef Cattle Research Center, Instituto de Zootecnia de Sertãozinho, were used, including 41 of the control line, 102 of the selection line and 152 of the traditional. The selection and traditional lines comprise animals selected for higher yearling weight, whereas control line animals are selected for yearling weight close to the average. Five alleles were identified, with allele 1 being the most frequent in the three lines, especially in the lines selected for higher means for yearling weight. Heterozygosity was significantly higher in the control line. Association analyses showed significant effects of allele 1 on birth weight and weaning weight while the allele 3 exert significant effects on yearling weight and back fat thickness. Despite these findings, application of this marker to marker-assisted selection requires more consistent results based on the genotyping of a larger number of animals in order to increase the accuracy of the statistical analyses.

  17. Study on the ionization chamber for thickness measurement

    International Nuclear Information System (INIS)

    Xue Shili; Miao Qiangwen

    1988-01-01

    The principle, construction and performances of ionization chambers for measuring the thickness of metal and nonmetal materials are introduced. With them the thickness of thin materials (thickness ranging from 10 to 6000 g/m 2 ), the surface layer thickness of composed materials and the thickness of steel plate (thickness ranging from 0 to 32 kg/m 2 ) are measured effectively

  18. Frequency noise in frequency swept fiber laser

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2013-01-01

    This Letter presents a measurement of the spectral content of frequency shifted pulses generated by a lightwave synthesized frequency sweeper. We found that each pulse is shifted in frequency with very high accuracy. We also discovered that noise originating from light leaking through the acousto......- optical modulators and forward propagating Brillouin scattering appear in the spectrum. © 2013 Optical Society of America....

  19. Translucency of dental ceramics with different thicknesses.

    Science.gov (United States)

    Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

    2013-07-01

    The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  20. Mechanical Properties of Additively Manufactured Thick Honeycombs

    Directory of Open Access Journals (Sweden)

    Reza Hedayati

    2016-07-01

    Full Text Available Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

  1. The Compton-thick Growth of Supermassive Black Holes constrained

    Science.gov (United States)

    Buchner, J.; Georgakakis, A.; Nandra, K.

    2017-10-01

    A heavily obscured growth phase of supermassive black holes (SMBH) is thought to be important in the co-evolution with galaxies. X-rays provide a clean and efficient selection of unobscured and obscured AGN. Recent work with deeper observations and improved analysis methodology allowed us to extend constraints to Compton-thick number densities. We present the first luminosity function of Compton-thick AGN at z=0.5-4 and constrain the overall mass density locked into black holes over cosmic time, a fundamental constraint for cosmological simulations. Recent studies including ours find that the obscuration is redshift and luminosity-dependent in a complex way, which rules out entire sets of obscurer models. A new paradigm, the radiation-lifted torus model, is proposed, in which the obscurer is Eddington-rate dependent and accretion creates and displaces torus clouds. We place observational limits on the behaviour of this mechanism.

  2. Film thickness determination by grazing incidence diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Battiston, G A; Gerbasi, R [CNR, Padua (Italy). Istituto di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati

    1996-09-01

    Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive.

  3. Residual stress analysis in thick uranium films

    International Nuclear Information System (INIS)

    Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.

    2005-01-01

    Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses

  4. Film thickness determination by grazing incidence diffraction

    International Nuclear Information System (INIS)

    Battiston, G. A.; Gerbasi, R.

    1996-01-01

    Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive

  5. Turbine airfoil with outer wall thickness indicators

    Science.gov (United States)

    Marra, John J; James, Allister W; Merrill, Gary B

    2013-08-06

    A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

  6. Through thickness property variations in a thick plate AA7050 friction stir welded joint

    International Nuclear Information System (INIS)

    Canaday, Clinton T.; Moore, Matthew A.; Tang, Wei; Reynolds, A.P.

    2013-01-01

    In this study, moderately thick (32 mm) AA7050 plates were joined by friction stir welding (FSW). Various methods were used to characterize the welded joints, including nugget grain size measurements at different locations through the thickness, micro-hardness indentation through nugget, thermo-mechanically affected zone (TMAZ), and heat affected zone (HAZ) at different cross section heights, and residual stress measurement using the cut compliance method with full thickness and partial thickness specimens. All testing results are consistent with the presence of a strong gradient in peak temperature through the plate thickness during FSW.

  7. Ice thickness measurements and volume estimates for glaciers in Norway

    Science.gov (United States)

    Andreassen, Liss M.; Huss, Matthias; Melvold, Kjetil; Elvehøy, Hallgeir; Winsvold, Solveig H.

    2014-05-01

    Whereas glacier areas in many mountain regions around the world now are well surveyed using optical satellite sensors and available in digital inventories, measurements of ice thickness are sparse in comparison and a global dataset does not exist. Since the 1980s ice thickness measurements have been carried out by ground penetrating radar on many glaciers in Norway, often as part of contract work for hydropower companies with the aim to calculate hydrological divides of ice caps. Measurements have been conducted on numerous glaciers, covering the largest ice caps as well as a few smaller mountain glaciers. However, so far no ice volume estimate for Norway has been derived from these measurements. Here, we give an overview of ice thickness measurements in Norway, and use a distributed model to interpolate and extrapolate the data to provide an ice volume estimate of all glaciers in Norway. We also compare the results to various volume-area/thickness-scaling approaches using values from the literature as well as scaling constants we obtained from ice thickness measurements in Norway. Glacier outlines from a Landsat-derived inventory from 1999-2006 together with a national digital elevation model were used as input data for the ice volume calculations. The inventory covers all glaciers in mainland Norway and consists of 2534 glaciers (3143 glacier units) covering an area of 2692 km2 ± 81 km2. To calculate the ice thickness distribution of glaciers in Norway we used a distributed model which estimates surface mass balance distribution, calculates the volumetric balance flux and converts it into thickness using the flow law for ice. We calibrated this model with ice thickness data for Norway, mainly by adjusting the mass balance gradient. Model results generally agree well with the measured values, however, larger deviations were found for some glaciers. The total ice volume of Norway was estimated to be 275 km3 ± 30 km3. From the ice thickness data set we selected

  8. Model SH intelligent instrument for thickness measuring

    International Nuclear Information System (INIS)

    Liu Juntao; Jia Weizhuang; Zhao Yunlong

    1995-01-01

    The authors introduce Model SH Intelligent Instrument for thickness measuring by using principle of beta back-scattering and its application range, features, principle of operation, system design, calibration and specifications

  9. Greenland Radar Ice Sheet Thickness Measurements

    Data.gov (United States)

    National Aeronautics and Space Administration — Two 150-MHz coherent radar depth sounders were developed and flown over the Greenland ice sheet to obtain ice thickness measurements in support of PARCA...

  10. Fabrication of thick superconducting films by decantation

    Directory of Open Access Journals (Sweden)

    Julián Betancourt M.

    1991-07-01

    Full Text Available We have found superconducting behavior in thick films fabricated by decantation. In this paper we present the experimental method and results obtained using commercial copper substrates.

  11. APPLIED ORIGAMI. Origami of thick panels.

    Science.gov (United States)

    Chen, Yan; Peng, Rui; You, Zhong

    2015-07-24

    Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures. Copyright © 2015, American Association for the Advancement of Science.

  12. Russian River Ice Thickness and Duration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of river ice thickness measurements, and beginning and ending dates for river freeze-up events from fifty stations in northern Russia. The...

  13. Central corneal thickness among glaucoma patients attending ...

    African Journals Online (AJOL)

    AAU_CHS

    ocular pressure measurement and is different among different ethnic population and subtypes of glaucoma. The central corneal thickness of different subtypes of glaucoma at Menelik II Hospital ... Intraocular pressure is a key element in the.

  14. Eddy current technologies for thick metal structures

    International Nuclear Information System (INIS)

    Takagi, Toshiyuki; Endo, Hisashi

    2004-01-01

    One of approach of an eddy current testing (ECT) for thick metal structures is introduced. The detection limit of ECT is capable of enlarging thick more than 10 mm, which is ordinarily about 5 mm, by the design of probe. On the basis of results of numerical analysis, the defect detection in thick and shape is evaluated by the distribution of experimental ECT signals. The problems of ECT for thick metal structures and measures, approach to probe design, the specifications of probe, evaluation of experimental results and defect detection are described. By ECT fast simulator, good slit sharp is simulated in the case of 10 and 20 mm of EDM slit length and 5, 10 and 15 mm of slit height. (S.Y.)

  15. investigating water absorption and thickness swelling tendencies

    African Journals Online (AJOL)

    HOD

    In addition, G30E (30% reinforced glass fibre in the epoxy composite) was more resilient to moisture ... determine its suitability as per its water absorption and thickness ... lower thermal conductivity and low density as outlined in the Tables.

  16. Arctic Sea Ice Freeboard and Thickness

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides measurements of sea ice freeboard and sea ice thickness for the Arctic region. The data were derived from measurements made by from the Ice,...

  17. [Application of N-isopropyl-p-[123I] iodoamphetamine quantification of regional cerebral blood flow using iterative reconstruction methods: selection of the optimal reconstruction method and optimization of the cutoff frequency of the preprocessing filter].

    Science.gov (United States)

    Asazu, Akira; Hayashi, Masuo; Arai, Mami; Kumai, Yoshiaki; Akagi, Hiroyuki; Okayama, Katsuyoshi; Narumi, Yoshifumi

    2013-05-01

    In cerebral blood flow tests using N-Isopropyl-p-[123I] Iodoamphetamine "I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method.

  18. Application of N-isopropyl-p-[123I] iodoamphetamine quantification of regional cerebral blood flow using iterative reconstruction methods. Selection of the optimal reconstruction method and optimization of the cutoff frequency of the preprocessing filter

    International Nuclear Information System (INIS)

    Asazu, Akira; Hayashi, Masuo; Arai, Mami; Kumai, Yoshiaki; Akagi, Hiroyuki; Okayama, Katsuyoshi; Narumi, Yoshifumi

    2013-01-01

    In cerebral blood flow tests using N-Isopropyl-p-[ 123 I] Iodoamphetamine 123 I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method. (author)

  19. Diode-pumped dual-frequency microchip Nd : YAG laser with tunable frequency difference

    Energy Technology Data Exchange (ETDEWEB)

    Ren Cheng; Zhang Shulian, E-mail: ren-c06@mails.tsinghua.edu.c [State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084 (China)

    2009-08-07

    The diode-pumped dual-frequency microchip Nd : YAG laser with tunable frequency difference is presented. The gain medium used is a microchip 2 mm in thickness for miniaturized and integrated design. Two quarter-wave plates are placed into the laser cavity and the intra-cavity birefringence produces two orthogonally linearly polarized modes. The rotation of one of the two quarter-wave plates introduces a controlled and variable cavity birefringence which causes a variable frequency difference between the two orthogonally polarized modes. The frequency difference can be tuned through the whole cavity free spectral range. The obtained frequency difference ranges from 14 MHz to 1.5 GHz. The variation of the beat frequency over a period of 10 min is less than 10 kHz. The lock-in between modes is not found. Experimental results are presented, which match well with the theoretical analysis based on Jones matrices.

  20. Rifting Thick Lithosphere - Canning Basin, Western Australia

    Science.gov (United States)

    Czarnota, Karol; White, Nicky

    2016-04-01

    The subsidence histories and architecture of most, but not all, rift basins are elegantly explained by extension of ~120 km thick lithosphere followed by thermal re-thickening of the lithospheric mantle to its pre-rift thickness. Although this well-established model underpins most basin analysis, it is unclear whether the model explains the subsidence of rift basins developed over substantially thick lithosphere (as imaged by seismic tomography beneath substantial portions of the continents). The Canning Basin of Western Australia is an example where a rift basin putatively overlies lithosphere ≥180 km thick, imaged using shear wave tomography. Subsidence modelling in this study shows that the entire subsidence history of the account for the observed subsidence, at standard crustal densities, the lithospheric mantle is required to be depleted in density by 50-70 kg m-3, which is in line with estimates derived from modelling rare-earth element concentrations of the ~20 Ma lamproites and global isostatic considerations. Together, these results suggest that thick lithosphere thinned to > 120 km is thermally stable and is not accompanied by post-rift thermal subsidence driven by thermal re-thickening of the lithospheric mantle. Our results show that variations in lithospheric thickness place a fundamental control on basin architecture. The discrepancy between estimates of lithospheric thickness derived from subsidence data for the western Canning Basin and those derived from shear wave tomography suggests that the latter technique currently is limited in its ability to resolve lithospheric thickness variations at horizontal half-wavelength scales of <300 km.