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Sample records for nonuniform phase shifts

  1. Analyzing algorithms for nonlinear and spatially nonuniform phase shifts in the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

    International Nuclear Information System (INIS)

    Jain, N.

    1999-03-01

    Phase-shifting interferometry has many advantages, and the phase shifting nature of the Liquid Crystal Point Diffraction Interferometer (LCPDI) promises to provide significant improvement over other current OMEGA wavefront sensors. However, while phase-shifting capabilities improve its accuracy as an interferometer, phase-shifting itself introduces errors. Phase-shifting algorithms are designed to eliminate certain types of phase-shift errors, and it is important to chose an algorithm that is best suited for use with the LCPDI. Using polarization microscopy, the authors have observed a correlation between LC alignment around the microsphere and fringe behavior. After designing a procedure to compare phase-shifting algorithms, they were able to predict the accuracy of two particular algorithms through computer modeling of device-specific phase shift-errors

  2. Optimal threshold of error decision related to non-uniform phase distribution QAM signals generated from MZM based on OCS

    Science.gov (United States)

    Han, Xifeng; Zhou, Wen

    2018-03-01

    Optical vector radio-frequency (RF) signal generation based on optical carrier suppression (OCS) in one Mach-Zehnder modulator (MZM) can realize frequency-doubling. In order to match the phase or amplitude of the recovered quadrature amplitude modulation (QAM) signal, phase or amplitude pre-coding is necessary in the transmitter side. The detected QAM signals usually have one non-uniform phase distribution after square-law detection at the photodiode because of the imperfect characteristics of the optical and electrical devices. We propose to use optimal threshold of error decision for non-uniform phase contribution to reduce the bit error rate (BER). By employing this scheme, the BER of 16 Gbaud (32 Gbit/s) quadrature-phase-shift-keying (QPSK) millimeter wave signal at 36 GHz is improved from 1 × 10-3 to 1 × 10-4 at - 4 . 6 dBm input power into the photodiode.

  3. Experimental investigation of zero phase shift effects for Coriolis flowmeters due to pipe imperfections

    DEFF Research Database (Denmark)

    Enz, Stephanie; Thomsen, Jon Juel; Neumeyer, Stefan

    2011-01-01

    damping and mass, and on ambient temperature changes. Experimental observations confirm the hypothesis that asymmetry in the axial distribution of damping will induce zero shifts similar to the phase shifts due to fluid flow. Axially symmetrically distributed damping was observed to influence phase shift......, the flexural vibrations of two bent, parallel, non-fluid-conveying pipes are studied experimentally, employing an industrial CFM. Special attention has been paid on the phase shift in the case of zero mass flow, i.e. the zero shift, caused by various imperfections to the ‘‘perfect’’ CFM, i.e. non-uniform pipe...... at an order of magnitude smaller than the primary effect of mass flow, while small added mass and ambient temperature changes induced zero shifts two orders of magnitude smaller than the phase shifts due to mass flow. The order of magnitude of the induced zero shifts indicates that non-uniform damping, added...

  4. Multicolor Holography With Phase Shifting

    Science.gov (United States)

    Vikram, Chandra S.

    1996-01-01

    Prototype apparatus constructed to test feasibility of two-color holographic interferometric scheme in which data for reconstructing holographic wavefront obtained with help of phase-shifting technique. Provides two sets of data needed to solve equations for effects of temperature and concentration. Concept extended to holography at three or more wavelengths to measure three or more phenomena associated with significant variations in index of refraction

  5. Non-uniformity of phase structure in immiscible polymer blends

    Czech Academy of Sciences Publication Activity Database

    Fortelný, Ivan; Lapčíková, Monika; Lednický, František; Starý, Zdeněk; Kruliš, Zdeněk

    2008-01-01

    Roč. 48, č. 3 (2008), s. 564-571 ISSN 0032-3888 R&D Projects: GA ČR GA106/06/0729; GA ČR GA106/06/0761 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer blends * melt mixing * non-uniform morphology Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.245, year: 2008

  6. Spatial dual-orthogonal (SDO) phase-shifting algorithm by pre-recomposing the interference fringe.

    Science.gov (United States)

    Wang, Yi; Li, Bingbo; Zhong, Liyun; Tian, Jindong; Lu, Xiaoxu

    2017-07-24

    In the case that the phase distribution of interferogram is nonuniform and the background/modulation amplitude change rapidly, the current self-calibration algorithms with better performance like principal components analysis (PCA) and advanced iterative algorithm (AIA) cannot work well. In this study, from three or more phase-shifting interferograms with unknown phase-shifts, we propose a spatial dual-orthogonal (SDO) phase-shifting algorithm with high accuracy through using the spatial orthogonal property of interference fringe, in which a new sequence of fringe patterns with uniform phase distribution can be constructed by pre-recomposing original interferograms to determine their corresponding optimum combination coefficients, which are directly related with the phase shifts. Both simulation and experimental results show that using the proposed SDO algorithm, we can achieve accurate phase from the phase-shifting interferograms with nonuniform phase distribution, non-constant background and arbitrary phase shifts. Specially, it is found that the accuracy of phase retrieval with the proposed SDO algorithm is insensitive to the variation of fringe pattern, and this will supply a guarantee for high accuracy phase measurement and application.

  7. Phase-shifted response of plasmonic nanostructures

    DEFF Research Database (Denmark)

    Nerkararyan, Khachatur V.; Yezekyan, Torgom S.; Bozhevolnyi, Sergey I.

    2017-01-01

    We analyze the dynamics of a quantum dipole emitter (QDE) illuminated by a resonant electromagnetic field and placed close to a metal nanostructure, whose response to the incident field is phase shifted by 3π/2 (-π/2). It is found that, due to the phase shift in a field scattered by the nanostruc......We analyze the dynamics of a quantum dipole emitter (QDE) illuminated by a resonant electromagnetic field and placed close to a metal nanostructure, whose response to the incident field is phase shifted by 3π/2 (-π/2). It is found that, due to the phase shift in a field scattered...

  8. Numerical analysis of nonminimum phase zero for nonuniform link design

    Science.gov (United States)

    Girvin, Douglas L.; Book, Wayne J.

    1991-01-01

    As the demand for light-weight robots that can operate in a large workspace increases, the structural flexibility of the links becomes more of an issue in control. When the objective is to accurately position the tip while the robot is actuated at the base, the system is nonminimum phase. One important characteristic of nonminimum phase systems is system zeros in the right half of the Laplace plane. The ability to pick the location of these nonminimum phase zeros would give the designer a new freedom similar to pole placement. This research targets a single-link manipulator operating in the horizontal plane and modeled as a Euler-Bernoulli beam with pinned-free end conditions. Using transfer matrix theory, one can consider link designs that have variable cross-sections along the length of the beam. A FORTRAN program was developed to determine the location of poles and zeros given the system model. The program was used to confirm previous research on nonminimum phase systems, and develop a relationship for designing linearly tapered links. The method allows the designer to choose the location of the first pole and zero and then defines the appropriate taper to match the desired locations. With the pole and zero location fixed, the designer can independently change the link's moment of inertia about its axis of rotation by adjusting the height of the beam. These results can be applied to the inverse dynamic algorithms that are currently under development.

  9. Tilt shift determinations with spatial-carrier phase-shift method in temporal phase-shift interferometry

    International Nuclear Information System (INIS)

    Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang; Wang, Baorui

    2014-01-01

    An algorithm is proposed to deal with tilt-shift errors in temporal phase-shift interferometry (PSI). In the algorithm, the tilt shifts are detected with the spatial-carrier phase-shift (SCPS) method and then the tilt shifts are applied as priori information to the least-squares fittings of phase retrieval. The algorithm combines the best features of the SCPS and the temporal PSI. The algorithm could be applied to interferograms of arbitrary aperture without data extrapolation for the Fourier transform is not involved. Simulations and experiments demonstrate the effectiveness of the algorithm. The statistics of simulation results show a satisfied accuracy in detecting tilt-shift errors. Comparisons of the measurements with and without environmental vibration show that the proposed algorithm could compensate tilt-shift errors and retrieve wavefront phase accurately. The algorithm provides an approach to retrieve wavefront phase for the temporal PSI in vibrating environment. (paper)

  10. Predicting phase shift of elastic waves in pipes due to fluid flow and imperfections

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Dahl, Jonas; Fuglede, Niels

    2009-01-01

    . This is relevant for understanding wave propagation in elastic media in general, and for the design and trouble-shooting of phase-shift measuring devices such as Coriolis mass flowmeters in particular. A multiple time scaling perturbation analysis is employed for a simple model of a fluid-conveying pipe......Flexural vibrations of a fluid-conveying pipe is investigated, with special consideration to the spatial shift in phase caused by fluid flow and various imperfections, e.g., non-ideal supports, non-uniform stiffness or mass, non-proportional damping, weak nonlinearity, and flow pulsation...

  11. Electronic Phase Shifting in Multipulse Rectifier

    Directory of Open Access Journals (Sweden)

    Sokol Yevgen I.

    2017-07-01

    Full Text Available This paper presents a novel converter which can reduce the harmonics like the conventional multipulse converters with input three phase transformer. To reduce total harmonic distortion of input current and improve the weight and size of converters, it is suggested to use multi-pulse rectifiers with an electronic phase shift. The basic module is a 6-pulse rectifier on fully controlled switches with the reverse blocking ability. Switching frequency either coincides or is twice the power frequency. The proposed solutions allow refusing from the electromagnetic phase-shifting devices (power transformers or auto-transformers and thereby significantly reduce the weight of the device. Unlike power factor correction systems with high-frequency modulation, the proposed converters are significantly different, as they have better electromagnetic compatibility and the virtual absence of dynamic switching losses of power switches.

  12. Michelson interferometer based spatial phase shift shearography.

    Science.gov (United States)

    Xie, Xin; Yang, Lianxiang; Xu, Nan; Chen, Xu

    2013-06-10

    This paper presents a simple spatial phase shift shearography based on the Michelson interferometer. The Michelson interferometer based shearographic system has been widely utilized in industry as a practical nondestructive test tool. In the system, the Michelson interferometer is used as a shearing device to generate a shearing distance by tilting a small angle in one of the two mirrors. In fact, tilting the mirror in the Michelson interferometer also generates spatial frequency shift. Based on this feature, we introduce a simple Michelson interferometer based spatial phase shift shearography. The Fourier transform (FT) method is applied to separate the spectrum on the spatial frequency domain. The phase change due to the loading can be evaluated using a properly selected windowed inverse-FT. This system can generate a phase map of shearography by using only a single image. The effects of shearing angle, spatial resolution of couple charge device camera, and filter methods are discussed in detail. The theory and the experimental results are presented.

  13. Suppression of Specular Reflections by Metasurface with Engineered Nonuniform Distribution of Reflection Phase

    Directory of Open Access Journals (Sweden)

    Xin Mi Yang

    2015-01-01

    Full Text Available We make preliminary investigations on a new approach to reducing radar cross section (RCS of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz, the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB for two orthogonal incident polarizations.

  14. Energy phase shift as mechanism for catalysis

    KAUST Repository

    Beke-Somfai, Tamás

    2012-05-01

    Catalysts are agents that by binding reactant molecules lower the energy barriers to chemical reaction. After reaction the catalyst is regenerated, its unbinding energy recruited from the environment, which is associated with an inevitable loss of energy. We show that combining several catalytic sites to become energetically and temporally phase-shifted relative to each other provides a possibility to sustain the overall reaction by internal \\'energy recycling\\', bypassing the need for thermal activation, and in principle allowing the system to work adiabatically. Using an analytical model for superimposed, phase-shifted potentials of F 1-ATP synthase provides a description integrating main characteristics of this rotary enzyme complex. © 2012 Elsevier B.V. All rights reserved.

  15. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

  16. Phase-shifting interferometer for surface inspection

    Science.gov (United States)

    Tam, Siu Chung; Low, Beng-Yew; Chua, Hock-Chuan; Ho, Anthony T. S.; Neo, Wah-Peng

    1997-08-01

    A phase-shifting Twyman-Green interferometer has been constructed. Using three consecutively captured interferograms, the phase profile of a reflective surface can be determined. Results using various fringe processing techniques are compared. These methods include uniform averaging, Gaussian mask and spin filtering. For simulated fringes superimposed with random noise and fixed-pattern noise, it has been observed that a combination of weighted averaging and spin filtering could generate the best results. The computerized system has been applied to the measurement of the form errors of a silicon wafer and a cosmetic mirror, respectively. The root-mean-square error of the wafer is determined to be 11.13 nm.

  17. Analytical predictions for vibration phase shifts along fluid-conveying pipes due to Coriolis forces and imperfections

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Dahl, Jonas

    2010-01-01

    Resonant vibrations of a fluid-conveying pipe are investigated, with special consideration to axial shifts in vibration phase accompanying fluid flow and various imperfections. This is relevant for understanding elastic wave propagation in general, and for the design and trouble-shooting of phase......-shift measuring devices such as Coriolis mass flowmeters in particular. Small imperfections related to elastic and dissipative support conditions are specifically addressed, but the suggested approach is readily applicable to other kinds of imperfection, e.g. non-uniform stiffness or mass, non...... the symmetric part of damping as well as non-uniformity in mass or stiffness do not affect phase shift. The validity of such hypotheses can be tested using detailed fluid-structure interaction computer models or laboratory experiments....

  18. Phase-step retrieval for tunable phase-shifting algorithms

    Science.gov (United States)

    Ayubi, Gastón A.; Duarte, Ignacio; Perciante, César D.; Flores, Jorge L.; Ferrari, José A.

    2017-12-01

    Phase-shifting (PS) is a well-known technique for phase retrieval in interferometry, with applications in deflectometry and 3D-profiling, which requires a series of intensity measurements with certain phase-steps. Usually the phase-steps are evenly spaced, and its knowledge is crucial for the phase retrieval. In this work we present a method to extract the phase-step between consecutive interferograms. We test the proposed technique with images corrupted by additive noise. The results were compared with other known methods. We also present experimental results showing the performance of the method when spatial filters are applied to the interferograms and the effect that they have on their relative phase-steps.

  19. Fast phase retrieval with four-quadrant analysis in phase-shifting interferometry with blind phase shifts

    Science.gov (United States)

    Xu, Yuanyuan; Wang, Yawei; Han, Hao; Liu, Jingye; Ji, Ying; Jin, Weifeng; Xu, Xiaoqing

    2018-01-01

    Phase-shifting interferometry (PSI) is one of the most effective techniques in optical measurement, in which phase retrieval with high efficiency is an important procedure. In this paper, a simple non-iterative method is proposed to extract the generalized phase shift with the four-quadrant analysis in three-frame PSI. In this method, the possible value of the phase shift is firstly worked out with the inner product algorithm, and then a criterion is put forward to accurately determine its principal value within the range [ 0 , 2 π ] , based on the change relationship of the interference wave vector in four quadrants. Thus, this method provides a possible method to solve the uncertainty of phase shift existing in some common algorithms. Subsequently, the phase can be retrieved easily without any other measurements. Both simulation and experimental results have fully proved the feasibility and high accuracy of the method. Moreover, it works well on open- and closed-fringed patterns.

  20. Theory of dispersive wave frequency shift via trapping by a soliton in an axially nonuniform optical fiber

    DEFF Research Database (Denmark)

    Judge, Alexander C.; Bang, Ole; de Sterke, Martin

    2010-01-01

    We extend the analytical theory explaining the trapping of normally dispersive waves by a Raman soliton in an axially uniform optical fiber to include axially nonuniform fibers. It is shown how a changing group velocity in such a fiber leads to the same trapping mechanism as for a decelerating...... Raman soliton in a uniform fiber. In contrast to this latter case, where the trapping always leads to a blueshift of the confined radiation, the additional design flexibility inherent in the nonuniform geometry permits the redshift of dispersive waves trapped by an accelerating soliton, which itself may...

  1. A Phase-Shifting Method for Improving the Heating Uniformity of Microwave Processing Materials

    Directory of Open Access Journals (Sweden)

    Yinhong Liao

    2016-04-01

    Full Text Available Microwave processing of materials has been found to deliver enormous advantages over conventional processing methods in terms of mechanical and physical properties of the materials. However, the non-uniform temperature distribution is the key problem of microwave processing, which is related to the structure of the cavity, and the placement and physical parameters of the material. In this paper, a new microwave cavity structure with a sliding short based on phase-shifting heating is creatively proposed to improve the temperature uniformity. An electronic mathematical model based on the Finite Element Method (FEM is built to predict the temperature distribution. Meanwhile, a new computational approach based on the theory of transformation optics is first provided to solve the problem of the moving boundary in the model simulation. At first, the experiment is carried out to validate the model, and heating results from the experiment show good agreement with the model’s prediction. Based on the verified model, materials selected among a wide range of dielectric constants are treated by stationary heating and phase-shifting heating. The coefficient of variation (COV of the temperature and temperature difference has been compared in detail between stationary heating and phase-shifting heating. A significant improvement in heating uniformity can be seen from the temperature distribution for most of the materials. Furthermore, three other materials are also treated at high temperature and the heating uniformity is also improved. Briefly, the strategy of phase-shifting heating plays a significant role in solve the problem of non-uniform heating in microwave-based material processing. A 25%–58% increase in uniformity from adapting the phase-shifting method can be observed for the microwave-processed materials.

  2. Array illumination with minimal non-uniformity based on generalized phase contrast

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2009-01-01

    The generalized phase contrast method (GPC) has been previously shown to be an efficient technique for generating array illumination and is thus highly suitable for such applications as dynamic multiple beam trapping and optical micromanipulation. However, projected arrays usually exhibit intensity...... output spots to improve uniformity. This is combined with matching corrections to the phase shift introduced by the phase contrast filter. Results from numerical experiments show that the array illumination uniformity error improves from over 40% to less than 1% while maintaining the efficiency prior...... roll-offs that may be undesirable for some applications. We show that the uniformity of GPC-generated array illuminations can be improved using intuitive corrections to the input spatial phase modulation, by increasing or decreasing it to respectively raise or lower the intensity of the corresponding...

  3. Theoretical investigations on two-phase flow instability in parallel channels under axial non-uniform heating

    International Nuclear Information System (INIS)

    Lu, Xiaodong; Wu, Yingwei; Zhou, Linglan; Tian, Wenxi; Su, Guanghui; Qiu, Suizheng; Zhang, Hong

    2014-01-01

    Highlights: • We developed a model based on homogeneous flow model to analyze two-phase flow instability in parallel channels. • The influence of axial non-uniform heating on the system stability has been investigated. • Influences of various factors on system instability under cosine heat flux have been studied. • The system under top-peaked heat flux is the most stable system. - Abstract: Two-phase flow instability in parallel channels heated by axial non-uniform heat flux has been theoretically studied in this paper. The system control equations of parallel channels were established based on the homogeneous flow model in two-phase region. Semi-implicit finite-difference scheme and staggered mesh method were used to discretize the equations, and the difference equations were solved by chasing method. Cosine, bottom-peaked and top-peaked heat fluxes were used to study the influence of non-uniform heating on two-phase flow instability of the parallel channels system. The marginal stability boundaries (MSB) of parallel channels and three-dimensional instability spaces (or instability reefs) under different heat flux conditions have been obtained. Compared with axial uniform heating, axial non-uniform heating will affect the system stability. Cosine and bottom-peaked heat fluxes can destabilize the system stability in high inlet subcooling region, while the opposite effect can be found in low inlet subcooling region. However, top-peaked heat flux can enhance the system stability in the whole region. In addition, for cosine heat flux, increasing the system pressure or inlet resistance coefficient can strengthen the system stability, and increasing the heating power will destabilize the system stability. The influence of inlet subcooling number on the system stability is multi-valued under cosine heat flux

  4. Uncertainty-managed phase-shifting digital holography.

    Science.gov (United States)

    Hahn, Joonku; Kim, Hwi

    2012-11-01

    Phase-shifting digital holography is a digital measurement technology of a complex optical field profile that uses focal plane array detectors without the loss of bandwidth. It has been known that the accuracy of phase-shifting digital holography is limited mainly by the phase tolerance of reference. In this Letter, it is revealed that the uncertainty in an expected signal is highly dependent on the phase of the signal itself, as well as the phase tolerance of the reference. Based on the uncertainty analysis, we propose a novel scheme of phase-shifting digital holography that exploits an uncertainty property to enhance the measurement accuracy even under significant reference phase tolerance.

  5. Model-based phase-shifting interferometer

    Science.gov (United States)

    Liu, Dong; Zhang, Lei; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian

    2015-10-01

    A model-based phase-shifting interferometer (MPI) is developed, in which a novel calculation technique is proposed instead of the traditional complicated system structure, to achieve versatile, high precision and quantitative surface tests. In the MPI, the partial null lens (PNL) is employed to implement the non-null test. With some alternative PNLs, similar as the transmission spheres in ZYGO interferometers, the MPI provides a flexible test for general spherical and aspherical surfaces. Based on modern computer modeling technique, a reverse iterative optimizing construction (ROR) method is employed for the retrace error correction of non-null test, as well as figure error reconstruction. A self-compiled ray-tracing program is set up for the accurate system modeling and reverse ray tracing. The surface figure error then can be easily extracted from the wavefront data in forms of Zernike polynomials by the ROR method. Experiments of the spherical and aspherical tests are presented to validate the flexibility and accuracy. The test results are compared with those of Zygo interferometer (null tests), which demonstrates the high accuracy of the MPI. With such accuracy and flexibility, the MPI would possess large potential in modern optical shop testing.

  6. Non-uniform sound intensity distributions when measuring absorption coefficients in reverberation chambers using a phased beam tracing

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2010-01-01

    sound intensity distributions on absorber under measurement conditions have been simulated using a phased beam tracing, and used as correction functions for reducing discrepancies between the measured and theoretical absorption coefficients. Two reverberation rooms were investigated by assuming...... that a test specimen was attached to a vertical surface and the floor. The frequency-dependent sound intensity distributions on absorbers were found to be affected by the reverberation chamber geometry and dimensions, the absorption capability of the specimen, and the placement of the specimen. High frequency...... agreement is found between corrected and measured statistical absorption coefficients. The non-uniform sound intensity can account for the discrepancy at high frequencies....

  7. Operator performance on the night shift: phases 1 and 2

    International Nuclear Information System (INIS)

    Morisseau, Dolores; Beere, Barnaby; Collier, Steve

    1999-04-01

    The objective of the project on operator performance on the night shift is to determine the effects of circadian rhythms on higher order cognitive processes. The project had two preliminary phases. Subjects were operators from the Halden Boiling Water Reactor, (Phase 1: 7 male operators and shift leaders, aged 26 to 35; Phase 2: 8 male operators and shift leaders, aged 26 to 53). The majority of the operators were the same for both studies. The preliminary work established that Norwegian operators' circadian rhythms fall within universal population norms and, thus, they are suitable subjects for such experiments. During Phase 1, two self-assessment instruments, the Stanford Sleepiness Scale (SSS) and the Global Vigour and Affect Scale (GVA), were administered every hour on all three shifts at the reactor. During Phase 2, three tests from the Walter Reed Performance Assessment Battery were administered at the beginning, middle, and end of each of the three shifts at the reactor. The tests (Serial Add-Subtract, Two-Column Addition, and Logical Reasoning) were administered using a hand-held computer. Both phases were conducted during regular work shifts for one complete shift rota (six weeks). ANOVA with two repeated measures showed that self-reported sleepiness on the night shift, sleepiness with respect to hours into the shift, and the interaction between them all reached statistical significance at p<.001. Data analyses (ANOVA) from Phase 2 indicate that the main effect of SHIFTNO (morning, afternoon, evening) on response times was significant (p<.002); the interaction between SHIFTNO and TINSHIFT (hours into shift) was also significant (p<.009). None of the effects on correctness of response was significant (Phase 2). While correctness of response was not significant for routine cognitive measures, the significant, progressive slowing of response times on the night shift reinforces the concern for possible performance decrements on the night shift. Thus, it

  8. Non-uniform sound intensity distributions when measuring absorption coefficients in reverberation chambers using a phased beam tracing.

    Science.gov (United States)

    Jeong, Cheol-Ho

    2010-06-01

    Measured absorption coefficients in reverberation chambers often differ from theoretical random incidence absorption coefficients, because ideal assumptions for the theoretical random incidence absorption coefficient are not fulfilled during measurements in actual reverberation chambers. Therefore sound intensity distributions on absorber under measurement conditions have been simulated using a phased beam tracing, and used as correction functions for reducing discrepancies between the measured and theoretical absorption coefficients. Two reverberation rooms were investigated by assuming that a test specimen was attached to a vertical surface and the floor. The frequency-dependent sound intensity distributions on absorbers were found to be affected by the reverberation chamber geometry and dimensions, the absorption capability of the specimen, and the placement of the specimen. High frequency intensity distributions above 1 kHz were similar for all studied cases, but some variations in low frequency intensity distributions were observed. If the non-uniform intensity distribution and a finite size effect are taken into account for correcting the theoretical absorption coefficients, a good agreement is found between corrected and measured statistical absorption coefficients. The non-uniform sound intensity can account for the discrepancy at high frequencies.

  9. Improving image quality of parallel phase-shifting digital holography

    International Nuclear Information System (INIS)

    Awatsuji, Yasuhiro; Tahara, Tatsuki; Kaneko, Atsushi; Koyama, Takamasa; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2008-01-01

    The authors propose parallel two-step phase-shifting digital holography to improve the image quality of parallel phase-shifting digital holography. The proposed technique can increase the effective number of pixels of hologram twice in comparison to the conventional parallel four-step technique. The increase of the number of pixels makes it possible to improve the image quality of the reconstructed image of the parallel phase-shifting digital holography. Numerical simulation and preliminary experiment of the proposed technique were conducted and the effectiveness of the technique was confirmed. The proposed technique is more practical than the conventional parallel phase-shifting digital holography, because the composition of the digital holographic system based on the proposed technique is simpler.

  10. SIMULATION OF CHARACTERISTICS OF DUAL-CORE PHASE SHIFTING TRANSFORMER

    Directory of Open Access Journals (Sweden)

    Kalinin L.P.

    2014-04-01

    Full Text Available The role and importance of phase shifting transformers are increased as a result of the further development of integrated power systems. This gives the rise to new technical solutions which entails the necessity of comparison of new developments with existing. The article consider the technical characteristics of dual-core phase shifting transformer which later will be used as a basis for comparison with other competing options and assess of their technical efficiency.

  11. Differentiating phase shift and delay in narrow band coherent signals.

    Science.gov (United States)

    Muthuraman, M; Govindan, R B; Deuschl, G; Heute, U; Raethjen, J

    2008-05-01

    Differentiating between a fixed activation pattern (phase shift) and conduction time (time delay) in rhythmic signals has important physiological implications but is methodologically difficult. Delay was estimated by the maximising coherence method and phase spectra calculated between (i) a narrow band-pass filtered AR2 process and its delayed copy for different phase shifts, (ii) the surface EMGs from two antagonistic forearm muscles with reciprocal alternating activity, and (iii) EEG and EMG data from 11 recordings in five Parkinsonian tremor patients. Estimated delays between the versions of the AR2 process resembled the real delay and were not significantly biased by the phase-shifts. The reciprocal alternating pattern of muscle activation was shown to be a pure phase-shift without any time delay. The phase between tremor-coherent cortical electrodes and EMG showed opposite signs and differed by 3pi/4-pi between the antagonistic muscles. Bidirectional delays between contralateral cortex and EMG did not differ between the antagonists and were in keeping with fast corticospinal transmission and feedback to the cortex for both muscles. Phase shifts and delays reflect different mechanisms in tremor related oscillatory interactions. The maximising coherence method can differentiate between them.

  12. Simultaneous measurement of temperature and strain using a phase-shifted fiber Bragg grating inscribed by femtosecond laser

    Science.gov (United States)

    Jiang, Yajun; Liu, Chi; Li, Dong; Yang, Dexing; Zhao, Jianlin

    2018-04-01

    A novel method for simultaneous measurement of temperature and strain using a single phase-shifted fiber Bragg grating (PS-FBG) is proposed. The PS-FBG is produced by exposing the fusion-spliced fiber with a femtosecond laser and uniform phase mask. Due to the non-uniform structure and strain distribution in the fusion-spliced region, the phase-shift changes with different responses during increases to the temperature and strain; by measuring the central wavelengths and the loss difference of two transmission dips, temperature and strain can be determined simultaneously. The resolutions of this particular sensor in measuring temperature and strain are estimated to be  ±1.5 °C and  ±12.2 µɛ in a range from  -50 °C to 150 °C and from 0 µɛ to 2070 µɛ.

  13. On the nucleon–nucleon scattering phase shifts through ...

    Indian Academy of Sciences (India)

    By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and ...

  14. Phase-shifting interference microscope with extendable field of measurement

    Science.gov (United States)

    Lin, Shyh-Tsong; Hsu, Wei-Feng; Wang, Ming-Shiang

    2018-04-01

    An innovative phase-shifting interference microscope aimed at extending the field of measurement is proposed in this paper. The microscope comprises a light source module, a phase modulation module, and an interferometric module, which reconstructs the micro-structure contours of samples using the five-step phase-shifting algorithm. This paper discusses the measurement theory and outlines the configuration, experimental setup, and experimental results obtained using the proposed interference microscope. The results confirm the efficacy of the microscope, achieving a standard deviation of 2.4 nm from a step height of 86.2 nm in multiple examinations.

  15. Digital phase-shifting atomic force microscope Moire method

    International Nuclear Information System (INIS)

    Liu Chiaming; Chen Lienwen

    2005-01-01

    In this study, the digital atomic force microscope (AFM) Moire method with phase-shifting technology is established to measure the in-plane displacement and strain fields. The Moire pattern is generated by the interference between the specimen grating and the virtual reference grating formed by digital image processes. The overlapped image is filtered by two-dimensional wavelet transformation to obtain the clear interference Moire patterns. The four-step phase-shifting method is realized by translating the phase of the virtual reference grating from 0 to 2π. The principle of the digital AFM Moire method and the phase-shifting technology are described in detail. Experimental results show that this method is convenient to use and efficient in realizing the microscale measurement

  16. Magnetic phase shift reconstruction for uniformly magnetized nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Akhtari-Zavareh, Azadeh [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA (United States); Kavanagh, Karen L. [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada)

    2017-01-15

    A new analytical model is developed for the magnetic phase shift of uniformly magnetized nanowires with ideal cylindrical geometry. The model is applied to experimental data from off-axis electron holography measurements of the phase shift of CoFeB nanowires, and the saturation induction of a selected wire, as well as its radius, aspect ratio, position and orientation, is determined by fitting the model parameters. The saturation induction value of 1.7 T of the CoFeB nanowire is found to be similar, to be within the measurement error, to values reported in the literature. - Highlights: • We describe a mathematical model for the magnetic phase shift of a cylindrical nanowire. • We discuss electron holography experiments on magnetic nanowires. • We obtain an accurate fit of the measured magnetic phase shift profile. • We extract the magnetic induction of the nanowire from the phase shift model. • The magnetic induction of 1.7 T agrees well with literature results.

  17. Parallel phase-shifting digital holography using spectral estimation technique.

    Science.gov (United States)

    Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu

    2014-09-20

    We propose a parallel phase-shifting digital holography using a spectral estimation technique, which enables the instantaneous acquisition of spectral information and three-dimensional (3D) information of a moving object. In this technique, an interference fringe image that contains six holograms with two phase shifts for three laser lines, such as red, green, and blue, is recorded by a space-division multiplexing method with single-shot exposure. The 3D monochrome images of these three laser lines are numerically reconstructed by a computer and used to estimate the spectral reflectance distribution of object using a spectral estimation technique. Preliminary experiments demonstrate the validity of the proposed technique.

  18. AC system stabilization via phase shift transformer with thyristor commutation

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Jose Carlos de; Guimaraes, Geraldo Caixeta; Moraes, Adelio Jose [Uberlandia Univ., MG (Brazil); Abreu, Jose Policarpo G. de [Escola Federal de Engenharia de Itajuba, MG (Brazil); Oliveira, Edimar Jose de [Juiz de Fora Univ., MG (Brazil)

    1994-12-31

    This article aims to present initially the constructive and operative forms of a phase-shift autotransformer which provides both magnitude and phase angle change through thyristor commutation, including a technic to reduce the number of thyristors. Following, it is proposed a control system to make such equipment an efficient AC system stabilizing tool. It is presented some simulation results to show the operation of this transformer in an electrical system. (author) 3 refs., 11 figs., 3 tabs.

  19. Nucleon-Nucleon Potentials and Computation of Scattering Phase Shifts

    Directory of Open Access Journals (Sweden)

    Jhasaketan Bhoi

    2015-12-01

    Full Text Available By judicious exploitation of supersymmetry formalism of quantum mechanics higher partial wave nucleon-nucleon potentials are generated from its ground state interactions. The nuclear Hulthen potential and the corresponding ground state wave function with the parameters of Arnold and MacKellar are used as the starting point of our calculation. We compute the scattering phase shifts for our constructed potentials through Phase Function Method to examine the merit of our approach to the problem.

  20. Generalized second-order Coulomb phase shift functions

    International Nuclear Information System (INIS)

    Rosendorff, S.

    1982-01-01

    Some specific properties and the evaluation of the generalized second-order Coulomb phase shift functions (two-dimensional integrals of four spherical cylinder functions) are discussed. The dependence on the three momenta k 1 ,k-bar,k 2 , corresponding to the final, intermediate, and initial states is illustrated

  1. Phase-shifting response to light in older adults.

    Science.gov (United States)

    Kim, Seong Jae; Benloucif, Susan; Reid, Kathryn Jean; Weintraub, Sandra; Kennedy, Nancy; Wolfe, Lisa F; Zee, Phyllis C

    2014-01-01

    Age-related changes in circadian rhythms may contribute to the sleep disruption observed in older adults. A reduction in responsiveness to photic stimuli in the circadian timing system has been hypothesized as a possible reason for the advanced circadian phase in older adults. This project compared phase-shifting responses to 2 h of broad-spectrum white light at moderate and high intensities in younger and older adults. Subjects included 29 healthy young (25.1 ± 4.1 years; male to female ratio: 8: 21) and 16 healthy older (66.5 ± 6.0 years; male to female ratio: 5: 11) subjects, who participated in two 4-night and 3-day laboratory stays, separated by at least 3 weeks. Subjects were randomly assigned to one of three different time-points, 8 h before (-8), 3 h before (-3) or 3 h after (+3) the core body temperature minimum (CBTmin) measured on the baseline night. For each condition, subjects were exposed in a randomized order to 2 h light pulses of two intensities (2000 lux and 8000 lux) during the two different laboratory stays. Phase shifts were analysed according to the time of melatonin midpoint on the nights before and after light exposure. Older subjects in this study showed an earlier baseline phase and lower amplitude of melatonin rhythm compared to younger subjects, but there was no evidence of age-related changes in the magnitude or direction of phase shifts of melatonin midpoint in response to 2 h of light at either 2000 lux or 8000 lux. These results indicate that the acute phase-shifting response to moderate- or high-intensity broad spectrum light is not significantly affected by age.

  2. Precision phase-shifting applied to fiber Bragg gratings

    DEFF Research Database (Denmark)

    Canning, John; Deyerl, Hans-Jürgen; Kristensen, Martin

    2005-01-01

    A simple method of displacing a holographic interferogram within a waveguide based on translation along a slightly tilted fringe pattern of the optical interferogram is presented. By way of example, phase-shifted fibre gratings are produced this way. The spatial resolution in fringe shift...... is separated from the physical spatial displacement of the optical elements and determined primarily by the fringe tilt angle. This relaxes the tolerances in optical components required and can potentially enable spatial displacements as small as 1 nm/@mm to be realised....

  3. Frequency domain phase retrieval of simultaneous multi-wavelength phase-shifting interferometry

    International Nuclear Information System (INIS)

    Yin, Zhenxing; Zhong, Liyun; Xu, Xiaofei; Zhang, Wangping; Lu, Xiaoxu; Tian, Jindong

    2016-01-01

    In simultaneous multi-wavelength phase-shifting interferometry, we propose a novel frequency domain phase retrieval (FDPR) algorithm. First, using only a one-time phase-shifting operation, a sequence of simultaneous multi-wavelength phase-shifting interferograms (SPSMWIs) are captured by a monochrome charge-coupled device. Second, by performing a Fourier transform for each pixel of SPSMWIs, the wrapped phases of each wavelength can be retrieved from the complex amplitude located in the spectral peak of each wavelength. Finally, the phase of the synthetic wavelength can be obtained by the subtraction between the wrapped phases of a single wavelength. In this study, the principle and the application condition of the proposed approach are discussed. Both the simulation and the experimental result demonstrate the simple and convenient performance of the proposed FDPR approach. (paper)

  4. Defect printability and repair of alternating phase-shift masks

    Science.gov (United States)

    Friedrich, Christoph M.; Verbeek, Martin; Mader, Leonhard; Crell, Christian; Pforr, Rainer; Griesinger, Uwe A.

    2000-02-01

    This paper will start with an overview of the different defect types which can occur on alternating phase shifting masks. A test mask with programmed defects of these different types was fabricated. The defect printability was investigated using an AIMS system. These results were correlated to first printing results in the wafer-fab. The results give an overview of the requirements for an inspection and repair system for alternating phase shifting masks. In order to get a better understanding of this printability behavior first simulations of defects using a 3D mask simulation tool were carried out and compared to the measurements. Several examples of quartz-repairs with different qualities are presented together with the influence on the aerial image.

  5. Nonlinearity response correction in phase-shifting deflectometry

    Science.gov (United States)

    Nguyen, Manh The; Kang, Pilseong; Ghim, Young-Sik; Rhee, Hyug-Gyo

    2018-04-01

    Owing to the nonlinearity response of digital devices such as screens and cameras in phase-shifting deflectometry, non-sinusoidal phase-shifted fringe patterns are generated and additional measurement errors are introduced. In this paper, a new deflectometry technique is described for overcoming these problems using a pre-distorted pattern combined with an advanced iterative algorithm. The experiment results show that this method can reconstruct the 3D surface map of a sample without fringe print-through caused by the nonlinearity response of digital devices. The proposed technique is verified by measuring the surface height variations in a deformable mirror and comparing them with the measurement result obtained using a coordinate measuring machine. The difference between the two measurement results is estimated to be less than 13 µm.

  6. Phase shift reflectometry for sub-surface defect detection

    Science.gov (United States)

    Asundi, Anand; Lei, Huang; Eden, Teoh Kang Min; Sreemathy, Parthasarathy; May, Watt Sook

    2012-11-01

    Phase Shift Reflectometry has recently been seen as a novel alternative to interferometry since it can provide warpage measurement over large areas with no need for large optical components. To confirm its capability and to explore the use of this method for sub-surface defect detection, a Chinese magic mirror is used. This bronze mirror which dates back to the Chinese Han Dynasty appears at first sight to be an ordinary convex mirror. However, unlike a normal mirror, when illuminated by a beam of light, an image is formed onto a screen. It has been hypothesized that there are indentations inside the mirror which alter the path of reflected light rays and hence the reflected image. This paper explores various methods to measure these indentations. Of the methods test Phase Shift Reflectometry (PSR) was found suitable to be the most suitable both in terms of the sensitivity and the field of view.

  7. The overall phase shift and lens effect calculation using Gaussian ...

    Indian Academy of Sciences (India)

    The solution was then used to derive expressions for the overall phase shift, focal length of the thermal lens and the end effect induced curvature of the end face. The expressions were then applied to Nd:YAG laser medium. The result shows a meaningful correction of the order of 0.001 cm to the focal length of Nd:YAG rod ...

  8. Cavity Attenuated Phase Shift (CAPS) Monitor Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, Arthur J. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-04-01

    The CAPS PMex monitor is a cavity attenuated phase shift extinction instrument. It operates as an optical extinction spectrometer, using a visible-light-emitting diode (LED) as the light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector. Its efficacy is based on the fact that aerosols are broadband scatterers and absorbers of light.

  9. High sensitivity Moire interferometry with phase shifting at nano resolution

    Science.gov (United States)

    Chen, Bicheng

    Due to insatiate demand for miniaturization of electronics, there is a need for new techniques to measure full-field strain at micro-scale structures. In addition, Micro-Electronic-Mechanical-Systems (MEMS) require a high resolution and high sensitivity material property characterization technique. In this study, a theoretic model for a high sensitivity Moire Interferometry (MI) for measuring nano-scale strain field has been developed. The study also includes the application of the proposed measurement technique for the study of reliability of next generation nano-electronics/power electronics. The study includes both theoretical and experimental work. In the theoretical part, a far field modeling of a Moire Interferometer (MI) using the mode decomposition method is proposed according to the analytical formulation from the scalar diffraction theory. The wave propagation within the defined MI far field domain is solved analytically for a single frequency surface relieved grating structure following the Rayleigh-Sommerfeld formulation under the paraxial approximation. It is shown that the far-field electrical field and the intensity interferogram can be calculated using the mode decomposition method. Furthermore, the near-field (propagation distance EM) theory; and the EM fields are simulated in a few microns region above the surface of the diffraction grating. The study shows that there is a strong correlation (correlation factor R = 0.869) of spatial frequency response between EM field and strain field at the nanoscale. Experimentally, a 164 nm/pixel spatial resolution Moire Interferometer with automated full strain field calculation is proposed. Accurate full strain field maps are generated automatically by a combination of phase shifting technique (temporal data redundancy) and Continuous Wavelet Transform (CWT) (spatial data redundancy). A thermal experiment on BGA packaging is used to demonstrate the advantages of the proposed new design. To enhance the

  10. The phase shifts leading to the broadening and shift of spectral lines

    Energy Technology Data Exchange (ETDEWEB)

    Roston, G.D. [Department of Physics, Faculty of Science, Alexandria University (Egypt)], E-mail: gamal_daniel@yahoo.com; Ghatass, Z.F. [Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University (Egypt); Obaid, F.S. [Department of Mathematics, Faculty of Science, Qubba University (Libyan Arab Jamahiriya)

    2009-02-15

    The classical theory of collisional broadening and shift parameters ({beta}, {delta}) of an isolated spectral line was used to obtain simple analytical formulas for calculating both {beta} and {delta}. These formulas were obtained on the assumption that the short range interaction is effective only in the broadening while the long range is effective in the shift of the spectral line. These parameters {beta} and {delta} depend on the limiting phase shifts responsible for broadening {eta}{sub b} and shift {eta}{delta}. It was found that the values of {eta}{sub b} and {eta}{sub {delta}} are not equal to each other as was proposed by Weisskopf {eta}{sub b}={eta}{sub {delta}}=1. The maximum and average values of {eta}{sub b} ({eta}{sub bmax}, {eta}{sub bav}) and {eta}{sub {delta}} ({eta}{sub {delta}}{sub max}, {eta}{sub {delta}}{sub av}) were obtained by numerical evaluation, using different inverse power potentials. By introducing these parameters into the approximated formulas for {beta} and {delta} using Van der Waals and Lennard-Jones potential, it was found that the results of calculations for ({beta} and {delta}) with different atomic transitions perturbed by different inert gases are in close agreement with earlier results. Those results, obtained earlier, were based on the Lindholm-Foley theory especially with the average values of {eta}{sub b} [{eta}{sub bav}=0.6057] and the maximum values of {eta}{sub {delta}} [{eta}{sub {delta}}{sub max}=1.57625]. The impact parameters {rho}{sub b} and {rho}{sub {delta}} leading to the broadening and shift of the spectral line were also obtained for different interactions. It was found that the end parameter for the broadening {rho}{sub b} is not equal to the starting parameter for the shift {rho}{sub {delta}}.

  11. Binary encoded computer generated holograms for temporal phase shifting.

    Science.gov (United States)

    Amphawan, Angela

    2011-11-07

    The trend towards real-time optical applications predicates the need for real-time interferometry. For real-time interferometric applications, rapid processing of computer generated holograms is crucial as the intractability of rapid phase changes may compromise the input to the system. This paper introduces the design of a set of binary encoded computer generated holograms (CGHs) for real-time five-frame temporal phase shifting interferometry using a binary amplitude spatial light modulator. It is suitable for portable devices with constraints in computational power. The new set of binary encoded CGHs is used for measuring the phase of the generated electric field for a real-time selective launch in multimode fiber. The processing time for the new set of CGHs was reduced by up to 65% relative to the original encoding scheme. The results obtained from the new interferometric technique are in good agreement with the results obtained by phase shifting by means of a piezo-driven flat mirror.

  12. Temporal dynamics of circadian phase shifting response to consecutive night shifts in healthcare workers: role of light-dark exposure.

    Science.gov (United States)

    Stone, Julia E; Sletten, Tracey L; Magee, Michelle; Ganesan, Saranea; Mulhall, Megan D; Collins, Allison; Howard, Mark; Lockley, Steven W; Rajaratnam, Shantha M W

    2018-03-28

    Shift work is highly prevalent and is associated with significant adverse health impacts. There is substantial inter-individual variability in the way the circadian clock responds to changing shift cycles. The mechanisms underlying this variability are not well understood. We tested the hypothesis that light-dark exposure is a significant contributor to this variability; when combined with diurnal preference, the relative timing of light exposure accounted for 71% of individual variability in circadian phase response to night shift work. These results will drive development of personalised approaches to manage circadian disruption among shift workers and other vulnerable populations to potentially reduce the increased risk of disease in these populations. Night shift workers show highly variable rates of circadian adaptation. This study examined the relationship between light exposure patterns and the magnitude of circadian phase resetting in response to night shift work. In 21 participants (nursing and medical staff in an intensive care unit) circadian phase was measured using 6-sulphatoxymelatonin at baseline (day/evening shifts or days off) and after 3-4 consecutive night shifts. Daily light exposure was examined relative to individual circadian phase to quantify light intensity in the phase delay and phase advance portions of the light phase response curve (PRC). There was substantial inter-individual variability in the direction and magnitude of phase shift after three or four consecutive night shifts (mean phase delay -1:08 ± 1:31 h; range -3:43 h delay to +3:07 h phase advance). The relative difference in the distribution of light relative to the PRC combined with diurnal preference accounted for 71% of the variability in phase shift. Regression analysis incorporating these factors estimated phase shift to within ±60 min in 85% of participants. No participants met criteria for partial adaptation to night work after three or four consecutive night

  13. Elimination of macrostep-induced current flow nonuniformity in vertical GaN PN diode using carbon-free drift layer grown by hydride vapor phase epitaxy

    Science.gov (United States)

    Fujikura, Hajime; Hayashi, Kentaro; Horikiri, Fumimasa; Narita, Yoshinobu; Konno, Taichiro; Yoshida, Takehiro; Ohta, Hiroshi; Mishima, Tomoyoshi

    2018-04-01

    In vertical GaN PN diodes (PNDs) grown entirely by metal–organic chemical vapor deposition (MOCVD), large current nonuniformity was observed. This nonuniformity was induced by macrosteps on the GaN surface through modulation of carbon incorporation into the n-GaN crystal. It was eliminated in a hybrid PND consisting of a carbon-free n-GaN layer grown by hydride vapor phase epitaxy (HVPE) and an MOCVD-regrown p-GaN layer. The hybrid PND showed a fairly low on-resistance (2 mΩ cm2) and high breakdown voltage (2 kV) even without a field plate electrode. These results clearly indicated the strong advantages of the HVPE-grown drift layer for improving power device performance, uniformity, and yield.

  14. Improvement of the accuracy of phase observation by modification of phase-shifting electron holography

    International Nuclear Information System (INIS)

    Suzuki, Takahiro; Aizawa, Shinji; Tanigaki, Toshiaki; Ota, Keishin; Matsuda, Tsuyoshi; Tonomura, Akira

    2012-01-01

    We found that the accuracy of the phase observation in phase-shifting electron holography is strongly restricted by time variations of mean intensity and contrast of the holograms. A modified method was developed for correcting these variations. Experimental results demonstrated that the modification enabled us to acquire a large number of holograms, and as a result, the accuracy of the phase observation has been improved by a factor of 5. -- Highlights: ► A modified phase-shifting electron holography was proposed. ► The time variation of mean intensity and contrast of holograms were corrected. ► These corrections lead to a great improvement of the resultant phase accuracy. ► A phase accuracy of about 1/4000 rad was achieved from experimental results.

  15. Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: II. Radial uniformity of the plasma characteristics

    International Nuclear Information System (INIS)

    Zhang Yuru; Xu Xiang; Wang Younian; Bogaerts, Annemie

    2012-01-01

    A two-dimensional fluid model, including the full set of Maxwell equations, has been developed and applied to investigate the effect of a phase shift between two power sources on the radial uniformity of several plasma characteristics in a hydrogen capacitively coupled plasma. This study was carried out at various frequencies in the range 13.56-200 MHz. When the frequency is low, at 13.56 MHz, the plasma density is characterized by an off-axis peak when both power sources are in-phase (φ = 0), and the best radial uniformity is obtained at φ = π. This trend can be explained because the radial nonuniformity caused by the electrostatic edge effect can be effectively suppressed by the phase-shift effect at a phase difference equal to π. When the frequency rises to 60 MHz, the plasma density profiles shift smoothly from edge-peaked over uniform to centre-peaked as the phase difference increases, due to the pronounced standing-wave effect, and the best radial uniformity is reached at φ = 0.3π. At a frequency of 100 MHz, a similar behaviour is observed, except that the maximum of the plasma density moves again towards the radial edge at the reverse-phase case (φ = π), because of the dominant skin effect. When the frequency is 200 MHz, the bulk plasma density increases significantly with increasing phase-shift values, and a better uniformity is obtained at φ = 0.4π. This is because the density in the centre increases faster than at the radial edge as the phase difference rises, due to the increasing power deposition P z in the centre and the decreasing power density P r at the radial edge. As the phase difference increases to π, the maximum near the radial edge becomes obvious again. This is because the skin effect has a predominant influence on the plasma density under this condition, resulting in a high density at the radial edge. Moreover, the axial ion flux increases monotonically with phase difference, and exhibits similar profiles to the plasma density

  16. Extended averaging phase-shift schemes for Fizeau interferometry on high-numerical-aperture spherical surfaces

    Science.gov (United States)

    Burke, Jan

    2010-08-01

    Phase-shifting Fizeau interferometry on spherical surfaces is impaired by phase-shift errors increasing with the numerical aperture, unless a custom optical set-up or wavelength shifting is used. This poses a problem especially for larger numerical apertures, and requires good error tolerance of the phase-shift method used; but it also constitutes a useful testing facility for phase-shift formulae, because a vast range of phase-shift intervals can be tested in a single measurement. In this paper I show how the "characteristic polynomials" method can be used to generate a phase-shifting method for the actual numerical aperture, and analyse residual cyclical phase errors by comparing a phase map from an interferogram with a few fringes to a phase mpa from a nulled fringe. Unrelated to the phase-shift miscalibration, thirdharmonic error fringes are found. These can be dealt with by changing the nominal phase shift from 90°/step to 60°/step and re-tailoring the evaluation formula for third-harmonic rejection. The residual error has the same frequency as the phase-shift signal itself, and can be removed by averaging measurements. Some interesting features of the characteristic polynomials for the averaged formulae emerge, which also shed some light on the mechanism that generates cyclical phase errors.

  17. Method of Designing Phase-Shifting Masks Utilizing a Compactor

    Science.gov (United States)

    Ooi, Kazuko; Koyama, Kiyomi; Kiryu, Masakazu

    1994-12-01

    A new method is proposed for designing Levenson-type phase-shifting masks. In this method, phases are assigned in an intermediate layout, and then the intermediate layout is converted to a final layout. In practice, the intermediate layout is a symbolic layout, and the symbolic layout is converted to a mask layout by a compactor. According to the strategy, no conflict spots arise during the operation, which greatly improves design efficiency. This design method is applicable to random patterns in a memory peripheral circuit and in microcomputer chips. As a result of application to the peripheral circuit of dynamic random access memory (DRAM), about 16% shrinkage of the mask area was obtained, compared with a conventional mask. As for a microcomputer chip, 12% shrinkage of mask area was obtained under the condition of 50% shrinkage of aluminum-wire spacing. Together with the interactive method reported before, which is applicable to a memory core circuit, the design of the Levenson-type masks for standard LSIs is totally covered.

  18. Investigation of phase error correction for digital sinusoidal phase-shifting fringe projection profilometry

    Science.gov (United States)

    Ma, S.; Quan, C.; Zhu, R.; Tay, C. J.

    2012-08-01

    Digital sinusoidal phase-shifting fringe projection profilometry (DSPFPP) is a powerful tool to reconstruct three-dimensional (3D) surface of diffuse objects. However, a highly accurate profile is often hindered by nonlinear response, color crosstalk and imbalance of a pair of digital projector and CCD/CMOS camera. In this paper, several phase error correction methods, such as Look-Up-Table (LUT) compensation, intensity correction, gamma correction, LUT-based hybrid method and blind phase error suppression for gray and color-encoded DSPFPP are described. Experimental results are also demonstrated to evaluate the effectiveness of each method.

  19. Measuring rainwater content by radar using propagation differential phase shift

    Science.gov (United States)

    Jameson, A. R.

    1994-01-01

    While radars measure several quantities closely coupled to the rainfall rate, for frequencies less than 15 GHz, estimates of the rainwater content W are traditionally computed from the radar reflectivity factor Z or the rate of attenuation A--quantities only weakly related to W. Consequently, instantaneous point estimates of W using Z and A are often erroneous. A more natural, alternative parameter for estimating W at these frequencies is the specific polarization propagation differential phase shift phi(sub DP), which is a measure of the change in the difference between phases of vertically (V) and horizontally (H) polarized waves with increasing distance from a radar. It is now well known that W is nearly linearly related to phi(sub DP) divided by (1 - reversed R), where reversed R is the mass-weighted mean axis ratio of the raindrops. Unfortunately, such relations are not widely used in part because measurements of phi(sub DP) are scarce but also because one must determine reversed R. In this work it is shown that this parameter can be estimated using the differential reflectivity (Z(sub H)/Z(sub V) at 3 GHz. An alternative technique is suggested for higher frequencies when the differential reflectivity becomes degraded by attenuation. While theory indicates that it should be possible using phi(sub DP) to estimate W quite accurately, measurement errors increase the uncertainty to +/- 18%-35% depending on reversed R. While far from ideal, it appears that these estimates are likely to be considerably more accurate than those deduced using currently available methods.

  20. Optimisation of Transmission Systems by use of Phase Shifting Transformers

    Energy Technology Data Exchange (ETDEWEB)

    Verboomen, J.

    2008-10-13

    In this thesis, transmission grids with PSTs (Phase Shifting Transformers) are investigated. In particular, the following goals are put forward: (a) The analysis and quantification of the impact of a PST on a meshed grid. This includes the development of models for the device; (b) The development of methods to obtain optimal coordination of several PSTs in a meshed grid. An objective function should be formulated, and an optimisation method must be adopted to solve the problem; and (c) The investigation of different strategies to use a PST. Chapter 2 gives a short overview of active power flow controlling devices. In chapter 3, a first step towards optimal PST coordination is taken. In chapter 4, metaheuristic optimisation methods are discussed. Chapter 5 introduces DC load flow approximations, leading to analytically closed equations that describe the relation between PST settings and active power flows. In chapter 6, some applications of the methods that are developed in earlier chapters are presented. Chapter 7 contains the conclusions of this thesis, as well as recommendations for future work.

  1. Black reefs: iron-induced phase shifts on coral reefs.

    Science.gov (United States)

    Kelly, Linda Wegley; Barott, Katie L; Dinsdale, Elizabeth; Friedlander, Alan M; Nosrat, Bahador; Obura, David; Sala, Enric; Sandin, Stuart A; Smith, Jennifer E; Vermeij, Mark J A; Williams, Gareth J; Willner, Dana; Rohwer, Forest

    2012-03-01

    The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to 0.75 km(2)). The phase shift occurs rapidly; the Kingman black reef formed within 3 years of the ship grounding. Iron concentrations in algae tissue from the Millennium black reef site were six times higher than in algae collected from reference sites. Metagenomic sequencing of the Millennium Atoll black reef-associated microbial community was enriched in iron-associated virulence genes and known pathogens. Microcosm experiments showed that corals were killed by black reef rubble through microbial activity. Together these results demonstrate that shipwrecks and their associated iron pose significant threats to coral reefs in iron-limited regions.

  2. Phase shift extraction and wavefront retrieval from interferograms with background and contrast fluctuations

    International Nuclear Information System (INIS)

    Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang

    2015-01-01

    The fluctuations of background and contrast cause measurement errors in the phase-shifting technique. To extract the phase shifts from interferograms with background and contrast fluctuations, an iterative algorithm is represented. The phase shifts and wavefront phase are calculated in two individual steps with the least-squares method. The fluctuation factors are determined when the phase shifts are calculated, and the fluctuations are compensated when the wavefront phase is calculated. The advantage of the algorithm lies in its ability to extract phase shifts from interferograms with background and contrast fluctuations converging stably and rapidly. Simulations and experiments verify the effectiveness and reliability of the proposed algorithm. The convergence accuracy and speed are demonstrated by the simulation results. The experiment results show its ability for suppressing phase retrieval errors. (paper)

  3. Iterative and noniterative nonuniform quantisation techniques in digital holography

    Science.gov (United States)

    Shortt, Alison E.; Naughton, Thomas J.; Javidi, Bahram

    2006-04-01

    Compression is essential for efficient storage and transmission of three-dimensional (3D) digital holograms. The inherent speckle content in holographic data causes lossless compression techniques, such as Huffman and Burrows-Wheeler (BW), to perform poorly. Therefore, the combination of lossy quantisation followed by lossless compression is essential for effective compression of digital holograms. Our complex-valued digital holograms of 3D real-world objects were captured using phase-shift interferometry (PSI). Quantisation reduces the number of different real and imaginary values required to describe each hologram. Traditional data compression techniques can then be applied to the hologram to actually reduce its size. Since our data has a nonuniform distribution, the uniform quantisation technique does not perform optimally. We require nonuniform quantisation, since in a histogram representation our data is denser around the origin (low amplitudes), thus requiring more cluster centres, and sparser away from the origin (high amplitudes). By nonuniformly positioning the cluster centres to match the fact that there is a higher probability that the pixel will have a low amplitude value, the cluster centres can be used more efficiently. Nonuniform quantisation results in cluster centres that are adapted to the exact statistics of the input data. We analyse a number of iterative (k-means clustering, Kohonen competitive neural network, SOM, and annealed Hopfield neural network), and non-iterative (companding, histogram, and optimal) nonuniform quantisation techniques. We discuss the strengths and weaknesses of each technique and highlight important factors that must be considered when choosing between iterative and non-iterative nonuniform quantisation. We measure the degradation due to lossy quantisation in the reconstruction domain, using the normalised rms (NRMS) metric.

  4. Phase shift effects for fluid conveying pipes with non-ideal supports

    DEFF Research Database (Denmark)

    Dahl, Jonas; Thomsen, Jon Juel

    2008-01-01

    Vibrations of a fluid-conveying pipe with non-ideal supports are investigated with respect to phase shift effects. A numerical Galerkin approach is developed for this general problem, and the use of it exemplified with a investigation of phase shift effects from rotational damping at supports...... of a simply supported pipe. It is found that asymmetric viscous rotational damping at supports gives rise to phase shifts along the pipe which cannot be distinguished from phase shift from mass flow. This is of interest, e.g., for the development and troubleshooting of Coriolis flow meters....

  5. Two-step phase retrieval algorithm based on the quotient of inner products of phase-shifting interferograms

    International Nuclear Information System (INIS)

    Niu, Wenhu; Zhong, Liyun; Sun, Peng; Zhang, Wangping; Lu, Xiaoxu

    2015-01-01

    Based on the quotient of inner products, a simple and rapid algorithm is proposed to retrieve the measured phase from two-frame phase-shifting interferograms with unknown phase shifts. Firstly, we filtered the background of interferograms by a Gaussian high-pass filter. Secondly, we calculated the inner products of the background-filtered interferograms. Thirdly, we extracted the phase shifts by the quotient of the inner products then calculated the measured phase by an arctangent function. Finally, we tested the performance of the proposed algorithm by the simulation calculation and the experimental research for a vortex phase plate. Both the simulation calculation and the experimental result showed that the phase shifts and the measured phase with high accuracy can be obtained by the proposed algorithm rapidly and conveniently. (paper)

  6. Effect of phase shift from corals to Zoantharia on reef fish assemblages.

    Science.gov (United States)

    Cruz, Igor C S; Loiola, Miguel; Albuquerque, Tiago; Reis, Rodrigo; Nunes, José de Anchieta C C; Reimer, James D; Mizuyama, Masaru; Kikuchi, Ruy K P; Creed, Joel C

    2015-01-01

    Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals) to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB), Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species) and phase-shift reefs (38 species), a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated.

  7. Effect of phase shift from corals to Zoantharia on reef fish assemblages.

    Directory of Open Access Journals (Sweden)

    Igor C S Cruz

    Full Text Available Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB, Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species and phase-shift reefs (38 species, a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated.

  8. Direct phase-shift measurement of an EUV mask with gradient absorber thickness

    Science.gov (United States)

    Tanabe, Hiroyoshi; Murachi, Tetsunori; Park, Seh-Jin; Gullikson, Eric M.; Abe, Tsukasa; Hayashi, Naoya

    2013-09-01

    We directly extracted the phase-shift values of an EUV mask by measuring the reflectance of the mask. The mask had gradient absorber thickness along vertical direction. We measured the reflectance of the open multilayer areas and the absorber areas by using an EUV reflectometer at various absorber thicknesses. We also measured the diffracted 0th order light intensities of grating patterns having several sizes of lines or holes. The phase-shift values were derived from these data assuming a flat mask interference model of the diffracted lights. This model was corrected by including the scattering amplitude from the pattern edges. We recalculated the phase-shift values which was free from the mask topological effect. The extracted phase-shift value was close to 180 degrees at 67 nm and 71 nm absorber thicknesses. The phase measurement error around 180 degree phase shift was 5 degrees (3σ).

  9. Experimental demonstration of 360 tunable RF phase shift using slow and fast light effects

    DEFF Research Database (Denmark)

    Xue, Weiqi; Sales, Salvador; Capmany, Jose

    2009-01-01

    A microwave photonic phase shifter realizing 360º phase shift over a RF bandwidth of more than 10 GHz is demonstrated using optical filtering assisted slow and fast light effects in a cascaded structure of semiconductor optical amplifiers.......A microwave photonic phase shifter realizing 360º phase shift over a RF bandwidth of more than 10 GHz is demonstrated using optical filtering assisted slow and fast light effects in a cascaded structure of semiconductor optical amplifiers....

  10. Optimization of second harmonic generation and nonlinear phase-shifts in the Cerenkov regime

    NARCIS (Netherlands)

    Krijnen, Gijsbertus J.M.; Torruellas, William; Stegeman, George J.; Hoekstra, Hugo; Lambeck, Paul

    We present Beam Propagation Method (BPM) studies of Second Harmonic Generation (SHG) and nonlinear phase-shifts by cascading. The studies concentrate on SHG by means of radiation modes; the Cerenkov regime. The presented modeling does take into account both depletion and nonlinear phase shifts of

  11. 3D measurement using combined Gray code and dual-frequency phase-shifting approach

    Science.gov (United States)

    Yu, Shuang; Zhang, Jing; Yu, Xiaoyang; Sun, Xiaoming; Wu, Haibin; Liu, Xin

    2018-04-01

    The combined Gray code and phase-shifting approach is a commonly used 3D measurement technique. In this technique, an error that equals integer multiples of the phase-shifted fringe period, i.e. period jump error, often exists in the absolute analog code, which can lead to gross measurement errors. To overcome this problem, the present paper proposes 3D measurement using a combined Gray code and dual-frequency phase-shifting approach. Based on 3D measurement using the combined Gray code and phase-shifting approach, one set of low-frequency phase-shifted fringe patterns with an odd-numbered multiple of the original phase-shifted fringe period is added. Thus, the absolute analog code measured value can be obtained by the combined Gray code and phase-shifting approach, and the low-frequency absolute analog code measured value can also be obtained by adding low-frequency phase-shifted fringe patterns. Then, the corrected absolute analog code measured value can be obtained by correcting the former by the latter, and the period jump errors can be eliminated, resulting in reliable analog code unwrapping. For the proposed approach, we established its measurement model, analyzed its measurement principle, expounded the mechanism of eliminating period jump errors by error analysis, and determined its applicable conditions. Theoretical analysis and experimental results show that the proposed approach can effectively eliminate period jump errors, reliably perform analog code unwrapping, and improve the measurement accuracy.

  12. An encryption scheme based on phase-shifting digital holography and amplitude-phase disturbance

    International Nuclear Information System (INIS)

    Hua Li-Li; Xu Ning; Yang Geng

    2014-01-01

    In this paper, we propose an encryption scheme based on phase-shifting digital interferometry. According to the original system framework, we add a random amplitude mask and replace the Fourier transform by the Fresnel transform. We develop a mathematical model and give a discrete formula based on the scheme, which makes it easy to implement the scheme in computer programming. The experimental results show that the improved system has a better performance in security than the original encryption method. Moreover, it demonstrates a good capability of anti-noise and anti-shear robustness

  13. Shift Multiplex Recording of Four-Valued Phase Data Pages by Volume Retardagraphy

    Directory of Open Access Journals (Sweden)

    Daisuke Barada

    2014-04-01

    Full Text Available In this paper, shift multiplex recording of phase data pages on a volume polarization-sensitive medium by retardagraphy is demonstrated. The origin of shift selectivity in volume retardagraphy is explained. In the experiment, four-valued phase data pages are used. Then, a coding method is proposed to correct a reconstructed phase pattern. The recorded phase data pages are reconstructed using the feature of the coding method. By comparing the reconstructed phase data pages with recording phase data pages, symbol error rates of less than 11% are achieved. From the experimental result, it is verified that volume retardagraphy is applicable to optical memory.

  14. Optical DPSK demodulator based on pi-phase-shifted fiber Bragg grating with an optically turnable phase shifter

    DEFF Research Database (Denmark)

    Kim, T.-Y.; Hanawa, M.; Kim, Sun-Jong

    2006-01-01

    We propose and demonstrate a novel optical differential phase-shift keying (DPSK) demodulator with an optically tunable phase shifter. The proposed DPSK demodulator is implemented by using a pi-phase-shifted fiber Bragg grating and an Yb3+-Al3+ codoped optical fiber. A 10-Gb/s DPSK signal...... was successfully demodulated by the proposed demodulator, showing clearly open eye diagrams as well as bit-error-free performance. Moreover, the phase of delayed optical signal can be tuned by the phase shifter that is controlled by a pumping light at around 980nm....

  15. Laser Doppler phase shifting using a high-speed digital micromirror device

    Science.gov (United States)

    Kuo, D.; Sharpe, J. P.

    2015-03-01

    Here we demonstrate the use of a binary spatial light modulator (Texas Instruments Digital Micromirror Device) to impart a phase shift to the beams of a laser Doppler velocimeter. Advantages of this approach to laser Doppler phase shifting include low cost, low power consumption, a precisely known phase-stepping frequency and the capability of working with a broad range of optical wavelengths. In the implementation shown here velocities of order 1 cm/s are measured.

  16. Phase-shifted Bragg grating inscription in PMMA microstructured POF using 248 nm UV radiation

    OpenAIRE

    Pereira, L.; Pospori, A.; Antunes, Paulo; Domingues, Maria Fatima; Marques, S.; Bang, Ole; Webb, David J.; Marques, Carlos A.F.

    2017-01-01

    In this work we experimentally validate and characterize the first phase-shifted polymer optical fiber Bragg gratings (PS-POFBGs) produced using a single pulse from a 248 nm krypton fluoride laser. A single-mode poly (methyl methacrylate) optical fiber with a core doped with benzyl dimethyl ketal for photosensitivity improvement was used. A uniform phase mask customized for 850 nm grating inscription was used to inscribe these Bragg structures. The phase shift defect was created directly duri...

  17. Mechanisms for phase shifting in cortical networks and their role in communication through coherence

    Directory of Open Access Journals (Sweden)

    Paul H E Tiesinga

    2010-11-01

    Full Text Available In the primate visual cortex, the phase of spikes relative to oscillations in the local field potential (LFP in the gamma frequency range (30-80Hz can be shifted by stimulus features such as orientation and thus the phase may carry information about stimulus identity. According to the principle of communication through coherence (CTC, the relative LFP phase between the LFPs in the sending and receiving circuits affects the effectiveness of the transmission. CTC predicts that phase shifting can be used for stimulus selection. We review and investigate phase shifting in models of periodically-driven single neurons and compare it with phase shifting in models of cortical networks. In a single neuron, as the driving current is increased, the spike phase varies systematically while the firing rate remains constant. In a network model of reciprocally connected excitatory (E and inhibitory (I cells phase shifting occurs in response to both injection of constant depolarizing currents and to brief pulses to I cells. These simple models provide an account for phase-shifting observed experimentally and suggest a mechanism for implementing CTC. We discuss how this hypothesis can be tested experimentally using optogenetic techniques.

  18. On the nucleon–nucleon scattering phase shifts through ...

    Indian Academy of Sciences (India)

    Abstract. By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase ...

  19. Quantum Phase Shift of a Moving Dipole under a Magnetic Field at a Distance

    Science.gov (United States)

    Lee, Kang-Ho; Kim, Young-Wan; Kang, Kicheon

    2018-03-01

    We predict a quantum phase shift of a moving electric dipole in the presence of an external magnetic field at a distance. On the basis of the Lorentz-covariant field interaction approach, we show that a phase shift appears in the internal dipole state under the condition that the dipole is moving in the field-free region, which is distinct from the topological He-McKellar-Wilkens phase generated by a direct overlap of the dipole and the field. We discuss the experimental feasibility of detecting this phase with atomic interferometry and argue that detection of this phase will resolve the question of the locality in quantum electromagnetic interaction.

  20. Phase retrieval from the phase-shift moiré fringe patterns in simultaneous dual-wavelength interferometry

    Science.gov (United States)

    Cheng, Jinlong; Gao, Zhishan; Bie, Shuyou; Dou, Yimeng; Ni, Ruihu; Yuan, Qun

    2018-02-01

    Simultaneous dual-wavelength interferometry (SDWI) could extend the measured range of each single-wavelength interferometry. The moiré fringe generated in SDWI indirectly represents the information of the measured long synthetic-wavelength ({λ }{{S}}) phase, thus the phase demodulation is rather arduous. To address this issue, we present a method to convert the moiré fringe pattern into a synthetic-wavelength interferogram (moiré to synthetic-wavelength, MTS). After the square of the moiré fringe pattern in the MTS method, the additive moiré pattern is turned into a multiplicative one. And the synthetic-wavelength interferogram could be obtained by a low-pass filtering in spectrum of the multiplicative moiré fringe pattern. Therefore, when the dual-wavelength interferometer is implemented with the π/2 phase shift at {λ }{{S}}, a sequence of synthetic-wavelength phase-shift interferograms with π/2 phase shift could be obtained after the MTS method processing on the captured moiré fringe patterns. And then the synthetic-wavelength phase could be retrieved by the conventional phase-shift algorithm. Compared with other methods in SDWI, the proposed MTS approach could reduce the restriction of the phase shift and frame numbers for the adoption of the conventional phase-shift algorithm. Following, numerical simulations are executed to evaluate the performance of the MTS method in processing time, frames of interferograms and the phase shift error compensation. And the necessary linear carrier for MTS method is less than 0.11 times of the traditional dual-wavelength spatial-domain Fourier transform method. Finally, the deviations for MTS method in experiment are 0.97% for a step with the height of 7.8 μm and 1.11% for a Fresnel lens with the step height of 6.2328 μm.

  1. EMP-002a Phase Shift through the Ionosphere

    Energy Technology Data Exchange (ETDEWEB)

    Soltz, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simons, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fenimore, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wilks, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carey, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-20

    In this note we review the derivation and use of the Ionospheric Transfer Function (ITF) in the DIO- RAMA model to calculate the propagation of a broad band ElectroMagnetic Pulse (EMP) through the Ionosphere in the limit of geometric optics. This note is intended to resolve a misunderstanding between the NDS VVA and EMP modeling teams regarding the appropriate use of the phase and group velocities in DIORAMA. The di erent approaches are documented in EMP-002 note, \\Phase vs. Group" [1], generated by the LLNL DIORAMA VVA team, and the subsequent response from the DIORAMA EMP modeling team' [2].

  2. Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

    DEFF Research Database (Denmark)

    Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

    2015-01-01

    An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

  3. Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography

    Science.gov (United States)

    Hasegawa, Shin-ya; Hirata, Ryo

    2018-02-01

    The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real time, and affording low-cost sensing. In this method, relatively low reference angles compared with that in the conventional method using phase shift between three or four pixels has been required. We propose an extended single-shot phase-shifting technique which uses the multiple-step phase-shifting algorithm and the corresponding multiple pixels which are the same as that of the period of an interference fringe. We have verified the theory underlying this recovery method by means of Fourier spectral analysis and its effectiveness by evaluating the visibility of the image using a high-resolution pattern. Finally, we have demonstrated high-contrast image recovery experimentally using a resolution chart. This method can be used in a variety of applications such as color holographic interferometry.

  4. Evaluation of Phase-Shifting Techniques for a Self-Referencing Interferometer Wavefront Sensor (Postprint)

    National Research Council Canada - National Science Library

    Corley, Melissa S; Rhoadarmer, Troy A

    2005-01-01

    ...) for applications requiring laser propagation in strong scintillation. This paper compares several phase-shifting techniques that can be used to capture interference patterns and examines their effects on SRI WFS performance...

  5. Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography

    Science.gov (United States)

    Hasegawa, Shin-ya; Hirata, Ryo

    2018-04-01

    The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real time, and affording low-cost sensing. In this method, relatively low reference angles compared with that in the conventional method using phase shift between three or four pixels has been required. We propose an extended single-shot phase-shifting technique which uses the multiple-step phase-shifting algorithm and the corresponding multiple pixels which are the same as that of the period of an interference fringe. We have verified the theory underlying this recovery method by means of Fourier spectral analysis and its effectiveness by evaluating the visibility of the image using a high-resolution pattern. Finally, we have demonstrated high-contrast image recovery experimentally using a resolution chart. This method can be used in a variety of applications such as color holographic interferometry.

  6. Quasiparticles in non-uniformly magnetized plasma

    International Nuclear Information System (INIS)

    Sosenko, P.P.

    1994-01-01

    A quasiparticle concept is generalized for the case of non-uniformly magnetized plasma. Exact and reduced continuity equations for the microscopic density in the quasiparticle phase space are derived, and the nature of quasiparticles is analyzed. The theory is developed for the general case of relativistic particles in electromagnetic fields, besides non-uniform but stationary magnetic fields. Effects of non-stationary magnetic fields are briefly investigated also. 26 refs

  7. Combined Coding And Modulation Employing Multi Phase Shift ...

    African Journals Online (AJOL)

    In this paper a technique for combining Huffman code, array code and phase modulation is proposed with a view to reduce redundancy, provide error control and simultaneously optimise on channel bandwidth. The combined scheme provides a reduction in overall complexity of the communication system as compared to a ...

  8. Error analysis of the phase-shifting technique when applied to shadow moire

    International Nuclear Information System (INIS)

    Han, Changwoon; Han Bongtae

    2006-01-01

    An exact solution for the intensity distribution of shadow moire fringes produced by a broad spectrum light is presented. A mathematical study quantifies errors in fractional fringe orders determined by the phase-shifting technique, and its validity is corroborated experimentally. The errors vary cyclically as the distance between the reference grating and the specimen increases. The amplitude of the maximum error is approximately 0.017 fringe, which defines the theoretical limit of resolution enhancement offered by the phase-shifting technique

  9. Experimental Demonstration of Capacity-Achieving Phase-Shifted Superposition Modulation

    DEFF Research Database (Denmark)

    Estaran Tolosa, Jose Manuel; Zibar, Darko; Caballero Jambrina, Antonio

    2013-01-01

    We report on the first experimental demonstration of phase-shifted superposition modulation (PSM) for optical links. Successful demodulation and decoding is obtained after 240 km transmission for 16-, 32- and 64-PSM.......We report on the first experimental demonstration of phase-shifted superposition modulation (PSM) for optical links. Successful demodulation and decoding is obtained after 240 km transmission for 16-, 32- and 64-PSM....

  10. Improved emission properties of polymer photonic crystal lasers by introducing a phase-shift

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

    2010-01-01

    Introducing a phase-shift in nanoimprinted polymer dye lasers is shown to increase the probability of single mode lasing from 19% to 99%. Low-index lasers with only one longitudinal mode are thus superior to band-edge lasers.......Introducing a phase-shift in nanoimprinted polymer dye lasers is shown to increase the probability of single mode lasing from 19% to 99%. Low-index lasers with only one longitudinal mode are thus superior to band-edge lasers....

  11. Synthetic circular-harmonic phase-only filter for shift, rotation and scaling-invariant correlation

    DEFF Research Database (Denmark)

    Zi-Liang, ping; Dalsgaard, Erik

    1995-01-01

    A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations......A syntetic circuler-harmonic phase-only filter is described. With this filter and a Fourier-transform correlator it is possible to obtain shift, rotation and scaling-invariant correlations...

  12. Large microwave phase shift and small distortion in an integrated waveguide device

    DEFF Research Database (Denmark)

    Öhman, Filip; Sales, Salvador; Chen, Yaohui

    2007-01-01

    We have obtained a tunable phase shift of 150 degrees in an integrated semiconductor waveguide by optimizing the interplay of fast and slow light effects. Furthermore, the distortions imposed by device nonlinearities have been quantified.......We have obtained a tunable phase shift of 150 degrees in an integrated semiconductor waveguide by optimizing the interplay of fast and slow light effects. Furthermore, the distortions imposed by device nonlinearities have been quantified....

  13. Single-shot femtosecond-pulsed phase-shifting digital holography.

    Science.gov (United States)

    Kakue, Takashi; Itoh, Seiya; Xia, Peng; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2012-08-27

    Parallel phase-shifting digital holography is capable of three-dimensional measurement of a dynamically moving object with a single-shot recording. In this letter, we demonstrated a parallel phase-shifting digital holography using a single femtosecond light pulse whose central wavelength and temporal duration were 800 nm and 96 fs, respectively. As an object, we set spark discharge in atmospheric pressure air induced by applying a high voltage to between two electrodes. The instantaneous change in phase caused by the spark discharge was clearly reconstructed. The reconstructed phase image shows the change of refractive index of air was -3.7 × 10(-4).

  14. Phase gradient algorithm based on co-axis two-step phase-shifting interferometry and its application

    Science.gov (United States)

    Wang, Yawei; Zhu, Qiong; Xu, Yuanyuan; Xin, Zhiduo; Liu, Jingye

    2017-12-01

    A phase gradient method based on co-axis two-step phase-shifting interferometry, is used to reveal the detailed information of a specimen. In this method, the phase gradient distribution can only be obtained by calculating both the first-order derivative and the radial Hilbert transformation of the intensity difference between two phase-shifted interferograms. The feasibility and accuracy of this method were fully verified by the simulation results for a polystyrene sphere and a red blood cell. The empirical results demonstrated that phase gradient is sensitive to changes in the refractive index and morphology. Because phase retrieval and tedious phase unwrapping are not required, the calculation speed is faster. In addition, co-axis interferometry has high spatial resolution.

  15. Phase-shift between arterial flow and ICP pulse during infusion test.

    Science.gov (United States)

    Kim, Dong-Joo; Czosnyka, Marek; Kim, Hakseung; Balédent, Olivier; Smielewski, Piotr; Garnett, Matthew R; Czosnyka, Zofia

    2015-04-01

    The dynamic relationship between pulse waveform of intracranial pressure (ICP) and transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) may contain information about cerebrospinal compliance. This study investigated the possibility by focusing on the phase shift between fundamental harmonics of CBFV and ICP. Thirty-seven normal pressure hydrocephalus patients (20 men, mean age 58) underwent the cerebrospinal fluid (CSF) infusion tests. The infusion was performed via pre-implanted Ommaya reservoir. The TCD FV was recorded in the middle cerebral artery. Resulting continuous ICP and pressure-volume (PV) signals were analyzed by ICM+ software. In initial stage of the CSF infusion, the phase shift was negative (median value = -11°, range = +60 to -117). There was significant inverse association of phase shift with brain elasticity (R = -0.51; p = 0.0009). In all tests, phase shift consistently decreased during gradual elevation of ICP (p = 0.00001). Magnitude of decrease in phase shift was inversely related to the peak-to-peak amplitude of ICP pulse waveform at a baseline (R = -0.51; p = 0.001). Phase shift between fundamental harmonics of ICP and TCD waveforms decreases during elevation of ICP. This is caused by an increase of time delay between systolic peak of flow velocity wave and ICP pulse.

  16. Endocrine and cardiovascular rhythms differentially adapt to chronic phase-delay shifts in rats.

    Science.gov (United States)

    Zeman, Michal; Molcan, Lubos; Herichova, Iveta; Okuliarova, Monika

    2016-01-01

    Disturbances in regular circadian oscillations can have negative effects on cardiovascular function, but epidemiological data are inconclusive and new data from animal experiments elucidating critical biological mechanisms are needed. To evaluate the consequences of chronic phase shifts of the light/dark (LD) cycle on hormonal and cardiovascular rhythms, two experiments were performed. In Experiment 1, male rats were exposed to either a regular 12:12 LD cycle (CONT) or rotating 8-h phase-delay shifts of LD every second day (SHIFT) for 10 weeks. During this period, blood pressure (BP) was monitored weekly, and daily rhythms of melatonin, corticosterone, leptin and testosterone were evaluated at the end of the experiment. In Experiment 2, female rats were exposed to the identical shifted LD schedule for 12 weeks, and daily rhythms of BP, heart rate (HR) and locomotor activity were recorded using telemetry. Preserved melatonin rhythms were found in the pineal gland, plasma, heart and kidney of SHIFT rats with damped amplitude in the plasma and heart, suggesting that the central oscillator can adapt to chronic phase-delay shifts. In contrast, daily rhythms of corticosterone, testosterone and leptin were eliminated in SHIFT rats. Exposure to phase shifts did not lead to increased body weight and elevated BP. However, a shifted LD schedule substantially decreased the amplitude and suppressed the circadian power of the daily rhythms of BP and HR, implying weakened circadian control of physiological and behavioural processes. The results demonstrate that endocrine and cardiovascular rhythms can differentially adapt to chronic phase-delay shifts, promoting internal desynchronization between central and peripheral oscillators, which in combination with other negative environmental stimuli may result in negative health effects.

  17. New apparatus for precise synchronous phase shift measurements in storage rings

    Directory of Open Access Journals (Sweden)

    Boris Podobedov

    1998-11-01

    Full Text Available Measuring a synchronous phase shift as a function of beam current is commonly done in accelerator physics to estimate the longitudinal impedance of a storage ring vacuum chamber. This measurement is normally done with RF techniques that do not have enough accuracy to detect small phase shifts typical to the newer storage rings. In this paper we report results from a new method for precise measurement of a synchronous phase shift. Our method involves downmixing from the RF frequency to a kHz range and then using an audio DSP lock-in amplifier for the actual phase detection. This paper describes the idea and the advantages of a new method as well as its practical implementation in the apparatus we build for precise synchronous phase measurements in the Stanford Linear Collider damping rings. The results of those measurements are also presented.

  18. Deliquescence phase transition measurements by quartz crystal microbalance frequency shifts.

    Science.gov (United States)

    Arenas, Kathleen Jane L; Schill, Steven R; Malla, Ammaji; Hudson, Paula K

    2012-07-26

    Measurements of the hygroscopic properties of aerosols are needed to better understand the role of aerosols as cloud condensation nuclei. Several techniques have been used to measure deliquescence (solid to liquid) phase transitions in particular. In this study, we have measured the deliquescence relative humidity (DRH) of organic and inorganic salts, organic acids (glutaric and succinic acid), and mixtures of organic acids with ammonium sulfate using a quartz crystal microbalance (QCM). The QCM allows for measurement of the deliquescence phase transition due to inherent measurement differences between solids and liquids in the oscillation frequency of a quartz crystal. The relative humidity dependent frequency measurements can be used to identify compounds that adsorb monolayer amounts of water or form hydrates prior to deliquescence (e.g., lithium chloride, potassium and sodium acetate). Although the amount of water uptake by a deliquescing material cannot be quantified with this technique, deliquescence measurements of mixtures of hygroscopic and nonhygroscopic components (e.g., ammonium sulfate and succinic acid (DRH > 95%)) show that the mass fraction of the deliquescing portion of the sample can be quantitatively determined from the relative change in oscillation frequency at deliquescence. The results demonstrate the use of this technique as an alternative method for phase transition measurements and as a direct measurement of the mass fraction of a sample that undergoes deliquescence. Further, deliquescence measurements by the QCM may provide improved understanding of discrepancies in atmospheric particle mass measurements between filter samples and the tapered element oscillating microbalance given the similar measurement principle employed by the QCM.

  19. Phase shifting-based debris effect detection in USV-assisted AFM nanomachining

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jialin [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100049 (China); Liu, Lianqing, E-mail: lianqingliu@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Yu, Peng; Cong, Yang [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Li, Guangyong [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA 15213 (United States)

    2017-08-15

    Highlights: • The mechanism of the debris effect on machining depth in force control mode operation is analyzed. • The relationship between phase shifting and pile-up of debris is investigated. • The phase shifting-based method is hardly affected by the pile-up of debris. • Debris effect detection by phase shifting-based method is achived. - Abstract: Atomic force microscopy (AFM) mechanical-based lithography attracts much attention in nanomanufacturing due to its advantages of low cost, high precision and high resolution. However, debris effects during mechanical lithography often lead to an unstable machining process and inaccurate results, which limits further applications of AFM-based lithography. There is a lack of a real-time debris detection approach, which is the prerequisite to eventually eliminating the influence of the debris, and of a method that can solve the above problems well. The ultrasonic vibration (USV)-assisted AFM has the ability to sense the machining depth in real time by detecting the phase shifting of cantilever. However, whether the pile-up of debris affect the phase response of cantilever is still lack of investigation. Therefore, we analyzed the mechanism of the debris effect on force control mode and investigated the relationship between phase shifting and pile-up of debris. Theoretical analysis and experimental results reveal that the pile-up of debris have negligible effect on phase shifting of cantilever. Therefore, the phase shifting-based method can detect the debris effect on machining depth in force control mode of AFM machining.

  20. Solution of the Cox-Thompson inverse scattering problem using finite set of phase shifts

    CERN Document Server

    Apagyi, B; Scheid, W

    2003-01-01

    A system of nonlinear equations is presented for the solution of the Cox-Thompson inverse scattering problem (1970 J. Math. Phys. 11 805) at fixed energy. From a given finite set of phase shifts for physical angular momenta, the nonlinear equations determine related sets of asymptotic normalization constants and nonphysical (shifted) angular momenta from which all quantities of interest, including the inversion potential itself, can be calculated. As a first application of the method we use input data consisting of a finite set of phase shifts calculated from Woods-Saxon and box potentials representing interactions with diffuse or sharp surfaces, respectively. The results for the inversion potentials, their first moments and asymptotic properties are compared with those provided by the Newton-Sabatier quantum inversion procedure. It is found that in order to achieve inversion potentials of similar quality, the Cox-Thompson method requires a smaller set of phase shifts than the Newton-Sabatier procedure.

  1. Edge effects in phase-shifting masks for 0.25-µm lithography

    Science.gov (United States)

    Wong, Alfred K. K.; Neureuther, Andrew R.

    1993-03-01

    The impact on image quality of scattering from phase-shifter edges and of interactions between phase-shifter and chrome edges is assessed using rigorous electromagnetic simulation. Effects of edge taper in phase-shift masks, spacing between phase-shifter and chrome edges, small outrigger features with a trench phase-shifter, and of the repair of phase defects by etching to 360 degree(s) are considered. Near field distributions and diffraction efficiencies are examined and images are compared with more approximate results from the commonly used Hopkins' theory of imaging.

  2. Out-phased decadal precipitation regime shift in China and the United States

    Science.gov (United States)

    Yang, Lichao; Fu, Zuntao

    2017-10-01

    In order to understand the changes in precipitation variability associated with the climate shift around mid-1970s, the precipitation regime changes have been analyzed over both China and the USA. Specifically, a new variable is designed based on Benford's Law (BL) to detect precipitation regime shift by using only the first digit information of the datasets. This new variable describes the decadal precipitation regime shift more directly and clearly than the traditional variables, such mean or trend of yearly precipitation amount. It is found that there is an obvious out-phased relation for precipitation regime shift over China and the USA, i.e., a significant shift from the lower to the higher BL's goodness of fit (weaker to stronger precipitation intensity) in the Southern China occurred in 1979, and a significant shift from the higher to the lower BL's goodness of fit (stronger to weaker precipitation intensity) in the USA occurred around 1978.

  3. A self-reference PRF-shift MR thermometry method utilizing the phase gradient

    International Nuclear Information System (INIS)

    Langley, Jason; Potter, William; Phipps, Corey; Zhao Qun; Huang Feng

    2011-01-01

    In magnetic resonance (MR) imaging, the most widely used and accurate method for measuring temperature is based on the shift in proton resonance frequency (PRF). However, inter-scan motion and bulk magnetic field shifts can lead to inaccurate temperature measurements in the PRF-shift MR thermometry method. The self-reference PRF-shift MR thermometry method was introduced to overcome such problems by deriving a reference image from the heated or treated image, and approximates the reference phase map with low-order polynomial functions. In this note, a new approach is presented to calculate the baseline phase map in self-reference PRF-shift MR thermometry. The proposed method utilizes the phase gradient to remove the phase unwrapping step inherent to other self-reference PRF-shift MR thermometry methods. The performance of the proposed method was evaluated using numerical simulations with temperature distributions following a two-dimensional Gaussian function as well as phantom and in vivo experimental data sets. The results from both the numerical simulations and experimental data show that the proposed method is a promising technique for measuring temperature. (note)

  4. Enhanced Measurement of Paper Basis Weight Using Phase Shift in Terahertz Time-Domain Spectroscopy

    Directory of Open Access Journals (Sweden)

    Mengbao Fan

    2017-01-01

    Full Text Available THz time-domain spectroscopy has evolved as a noncontact, safe, and efficient technique for paper characterization. Our previous work adopted peak amplitude and delay time as features to determine paper basis weight using terahertz time-domain spectroscopy. However, peak amplitude and delay time tend to suffer from noises, resulting in degradation of accuracy and robustness. This paper proposes a noise-robust phase-shift based method to enhance measurements of paper basis weight. Based on Fresnel Formulae, the physical relationship between phase shift and paper basis weight is formulated theoretically neglecting multiple reflections in the case of normal incidence. The established formulation indicates that phase shift correlates linearly with paper basis weight intrinsically. Subsequently, paper sheets were stacked to fabricate the samples with different basis weights, and experimental results verified the developed mathematical formulation. Moreover, a comparison was made between phase shift, peak amplitude, and delay time with respect to linearity, accuracy, and noise robustness. The results show that phase shift is superior to the others.

  5. Solitary waves of surface plasmon polariton via phase shifts under Doppler broadening and Kerr nonlinearity

    Science.gov (United States)

    Ahmad, S.; Ahmad, A.; Bacha, B. A.; Khan, A. A.; Abdul Jabar, M. S.

    2017-12-01

    Surface Plasmon Polaritons (SPPs) are theoretically investigated at the interface of a dielectric metal and gold. The output pulse from the dielectric is used as the input pulse for the generation of SPPs. The SPPs show soliton-like behavior at the interface. The solitary form of a SPP is maintained under the effects of Kerr nonlinearity, Doppler broadening and Fresnel dragging whereas its phase shift is significantly modified. A 0.3radian phase shift is calculated in the presence of both Kerr nonlinearity and Fresnel dragging in the absence of plasma motion. The phase shift is enhanced to 60radian due to the combined effect of Doppler broadening, Kerr nonlinearity and Fresnel dragging. The results may have significant applications in nano-photonics, optical tweezers, photovoltaic devices, plasmonster and sensing technology.

  6. Two-shot point-diffraction interferometer with an unknown phase shift

    International Nuclear Information System (INIS)

    Bai, Fuzhong; Liu, Zhen; Bao, Xiaoyan

    2010-01-01

    On the basis of a modified Mach–Zehnder interferometer, this paper proposes a two-shot point-diffraction interferometer (PDI), by which two π-shifted interferograms are created according to the principle of half-wave loss and are simultaneously captured by a single CCD camera. After an arbitrary unknown phase shift is induced, a second and final shot captures these last two patterns. Then a novel algorithm based on statistical principles is developed to extract the actual phase shift and the wavefront phase from four interferograms. The combination of two required shots and a robust algorithm allows the proposed PDI to be implemented efficiently and accurately. Related simulation and experiments are conducted to prove the correctness of the proposed method

  7. Strain Measurement Using Phase-shifting Digital Holography with Two Cameras

    Directory of Open Access Journals (Sweden)

    Morimoto Y.

    2010-06-01

    Full Text Available Phase-shifting digital holography is a convenient method to measure displacement and strain distributions. Development of compact and conventional strain distribution measurement equipment for practical use is required for inspection of health monitoring and life lengthening of infrastructures such as steel bridges. In this paper, we propose an off-axis reconstruction method for displacement and strain distribution measurement with a phase-shifting digital holography. In the case of off-axis optical setup, the pitch of the fringe appearing on the image sensor becomes smaller than a pixel size. However, the phase-shifting digital hologram can be obtained even if the off-axis setup and effective results can be obtained using a Windowed-PSDHI. The principle and the experimental result of strain distribution measurement was performed with this method using two cameras.

  8. Analysis of a micropolarizer array-based simultaneous phase-shifting interferometer.

    Science.gov (United States)

    Novak, Matt; Millerd, James; Brock, Neal; North-Morris, Michael; Hayes, John; Wyant, James

    2005-11-10

    Recent technological innovations have enabled the development of a new class of dynamic (vibration-insensitive) interferometer based on a CCD pixel-level phase-shifting approach. We present theoretical and experimental results for an interferometer based on this pixelated phase-shifting technique. Analyses of component errors and instrument functionality are presented. We show that the majority of error sources cause relatively small magnitude peak-to-valley errors in measurement of the order of 0.002-0.005lambda. These errors are largely mitigated by high-rate data acquisition and consequent data averaging.

  9. Low energy pion-pion phase shifts from chiral perturbation theory

    International Nuclear Information System (INIS)

    Borges, J. Sa; Barbosa, J. Soares; Oguri, V.

    1997-01-01

    The low energy pion-pion S- and P- experimental phase-shifts are fitted with chiral perturbation theory (Ch PT) amplitude. The low energy pion-pion S- and P- experimental phase-shifts. The parameters l 1 and l 2 of the one loop corrected amplitude are fixed and the corresponding values of the scattering lengths are calculated. We propose that the present method is the best way to fix Ch P T parameters. The unitarization program of current algebra is also discussed. (author)

  10. Extracting scattering phase shifts in higher partial waves from lattice QCD calculations

    Energy Technology Data Exchange (ETDEWEB)

    Luu, Thomas; Savage, Martin J.

    2011-06-01

    Lüscher’s method is routinely used to determine meson-meson, meson-baryon, and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from lattice QCD calculations—presently at unphysical light-quark masses. In this work we review the formalism and develop the requisite expressions to extract phase shifts describing meson-meson scattering in partial waves with angular momentum l≤6 and l=9. The implications of the underlying cubic symmetry, and strategies for extracting the phase shifts from lattice QCD calculations, are presented, along with a discussion of the signal-to-noise problem that afflicts the higher partial waves.

  11. Phase-shifting digital holographic microscopy by using a multi-camera setup.

    Science.gov (United States)

    Trujillo, Carlos; Garcia-Sucerquia, Jorge

    2017-12-01

    In this Letter, the use of two-coupled Mach-Zehnder interferometers for four π/2-phase shifting interferometry is introduced. A multi-camera arrangement using no more than beam splitters and mirrors is utilized to obtain in a single shot the needed phase-shifted interferograms in the different output channels of the setup. The simplicity of the setup makes it ideal for high-speed interferometry applications. This proposal is validated in digital holographic microscopy to visualize a biological sample of epidermal onion cells.

  12. Effect of asymmetric actuator and detector position on Coriolis flowmeter and measured phase shift

    DEFF Research Database (Denmark)

    Enz, Stephanie

    2010-01-01

    Coriolis flowmeters (CFM) are forced to vibrate by a periodic excitation usually applied midpipe through an electromagnetic actuator. From hands-on experience with industrial CFMs it appears, that the electromagnetic actuator has to be located as symmetric as possible. For CFM design and trouble-shooting...... position, e.g. due to manufacturing variations or improper handling of the CFM, induces a phase shift that leads to changes of the meter’s sensitivity, and could therefore result into erroneous measurements of the mass flow. This phase shift depends on the mass flow and does not contribute to a lacking...

  13. Characteristics of the Phase-shifting Transformer Realized According to the "Polygon" Connection

    Directory of Open Access Journals (Sweden)

    Kalinin L.P.

    2017-12-01

    Full Text Available The object of the study is a two-transformer phase-shifting device with a span of adjustment of the angle of phase shift . In order to determine the energy characteristics of the investigated device, it has been put the scope to study the regime's parameters, performing adjustment of the angle of phase shift. This was made possible due to the use of the thyristor key for 10 positions and the low of it’s switching. The model was developed for a series of computational experiments for the cases of: idle, short circuit and loaded regime. A comparative analysis of the technical characteristics of the studied device, with the phase-reversing transformers investigated earlier has been carried out. The novelty of the work consists in the development of a scheme of a two-transformer phase regulating device. The additional winding of the magnetizing transformer was connected on an opposite side to the winding of the phase-shifting transformer. It has been achieved a reduction in the value of the magnetic induction in the core, as well as an increase of the stability in the process of adjusting the angle of phase shift. The analysis of the obtained characteristics of the device made it possible, by comparison with the available variants of existing circuits, to conclude that the developed one was of increased technical efficiency. The proposed technical solution decreased the installed capacity of the equipment, which in turn lead to a reduction of the weight and size indices and, as a consequence, of its cost.

  14. Nucleon-alpha particle interactions from inversion of scattering phase shifts

    International Nuclear Information System (INIS)

    Alexander, N.; Amos, K.; Apagyi, B.; Lun, D.R.

    1996-01-01

    Scattering amplitudes have been extracted from (elastic scattering) neutron-alpha (n-α) differential cross sections below threshold using the constraint that the scattering function is unitary. Real phase shifts have been obtained therefrom. A modification to the Newton iteration method has been used to solve the nonlinear equation that specifies the phase of the scattering amplitude in terms of the complete (0 to 180 deg) cross section since the condition for a unique and convergent solution by an exact iterated fixed point method, the 'Martin' condition, is not satisfied. The results compare well with those found using standard optical model search procedures. Those optical model phase shifts, from both n - α and p - α (proton-alpha) calculations in which spin-orbit effects were included, were used in the second phase of this study, namely to determine the scattering potentials by inversion of that phase shift data. A modified Newton-Sabatier scheme to solve the inverse scattering problem has been used to obtain inversion potentials (both central and spin-orbit) for nucleon energies in the range 1 to 24 MeV. The inversion interactions differ noticeably from the Woods-Saxon forms used to give the input phase shifts. Not only do those inversion potentials when used in Schroedinger equations reproduce the starting phase shifts but they are also very smooth, decay rapidly, and are as feasible as the optical model potentials of others to be the local form for interactions deduced by folding realistic two-nucleon g matrices with the density matrix elements of the alpha particle. 23 refs., 8 tabs., 9 figs

  15. Imaging behavior of high-transmission attenuating phase-shift mask films

    Science.gov (United States)

    Hibbs, Michael; Nemoto, Satoru; Komizo, Toru

    2006-10-01

    The properties of phase shifting attenuator films are quantified in a variety of ways. Transverse dimensions are measured by optical microscopes or scanning electron microscopes. Vertical dimension and profiles are measured by atomic force microscopes or indirectly by optical scatterometry. The complex refractive index of an attenuator film can be characterized by ellipsometry or by spectroscopic analysis of reflected and transmitted light. Transmission and phase measurements can be made with optical interferometric techniques. Data acquired in these ways can be used as inputs to simulation programs to model the image forming characteristics of the films. For simplicity and speed of calculation, the simulation programs typically use a thin-mask approximation, in which the vertical absorber geometry is ignored and the phase shifting attenuator regions are characterized only by their transmission, phase shift, and two-dimensional geometric shapes. Inclusion of the full three-dimensional profile and complex refractive index of the absorber can be done, but at the cost of greatly increased calculation time and a loss of the simplicity of understanding afforded by the thin-mask model. For example, the thin-mask model assumes that every geometrical feature etched into a given attenuator film will have the same phase and transmission properties. Comparison of thin-mask modeling results with the full three dimensional model shows that this assumption is not true. The effective dimensional bias, phase, transmission, and defocus are strong functions of the feature size, pitch, and complex refractive index of the film. Three dimensional simulations were run for several commercial and developmental high-transmission phase-shifting attenuator films. The effective phase and dimensional printing bias were calculated as a function of pitch for each film. Surprising differences were found in the results for the various film types.

  16. An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lian, S.; Yang, H., E-mail: yang.haiquan@gmail.com [Midorino Research Corporation, 5-15-13 Chuo Rinkan Nishi, Yamato, Kanagawa 242-0008 (Japan); Kudo, H. [Division of Information Engineering, Faculty of Engineering, Information and Systems, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573 (Japan); Momose, A.; Yashiro, W. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2015-02-15

    The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called “Talbot effect” by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

  17. Polarization-independent, differential-phase-shift, quantum-key distribution system using upconversion detectors.

    Science.gov (United States)

    Iwai, Yuki; Honjo, Toshimori; Inoue, Kyo; Kamada, Hidehiko; Nishida, Yoshiki; Tadanaga, Osamu; Asobe, Masaki

    2009-05-15

    We propose and demonstrate a polarization-independent, differential-phase-shift, quantum-key distribution system with upconversion detectors. Even though the detectors have polarization dependency, use of alternative polarization modulation and a two-bit delay interferometer achieves polarization-insensitive operation. In an experiment, sifted key bits were polarization-independently generated over 50 km fiber.

  18. Dependence of gain and phase-shift on crystal parameters and ...

    Indian Academy of Sciences (India)

    The two-beam coupling gain is directional and is determined by the symmetry, alignment and. 709 ... the formed interference pattern moves through the volume of the crystal along the z-axis with the speed v = ω/k, ... the index grating will have a spatial phase-shift relative to the interference fringe pattern [6]. The index of ...

  19. Topics in phase-shift analysis and higher spin field theory

    International Nuclear Information System (INIS)

    Reisen, J.C.J.M.

    1983-01-01

    The first part of this thesis considers several aspects of the existence of phase-shift ambiguities. The subject is introduced with a few remarks on scattering theory and previous work in this area is discussed. The mathematical restrictions of presenting such problems clearly are considered and the construction of different unitary amplitudes which correspond to the same differential cross section is described. So far, examples of phase-shift ambiguities have only been found for rather special cases but the author shows that these results can be considerably generalized for spinless elastic scattering, leading to properties of phase-shift ambiguities being revealed that were previously absent. These properties are discussed in detail. Phase-shift ambiguities for the spin-0-spin-1/2 elastic scattering are then considered and again generalized. The second part of this thesis is concerned with the investigation of a free field theory for both massive and massless particles with higher spin (1, 2 and 3). A root method has been used which is described and shown to lead to the free field equations and the subsidiary conditions. A field equation and Lagrangian are constructed for massive particles and the former is then used to derive a massless field equation and Lagrangian. The relation between massive and massless field equations is investigated in more detail and particularly the expressions for the amplitude describing exchange of a particle between two external sources are compared. (Auth./C.F.)

  20. Comparing DLLs and Shift Registers for Low-Jitter Multi-phase Clock Generation

    NARCIS (Netherlands)

    Gao, X.; Klumperink, Eric A.M.; Nauta, Bram

    2007-01-01

    In this paper we compare a Shift Register (SR) to a Delay Locked Loop (DLL) for Multi Phase Clock Generation (MPCG), and motivate why a SR is often better. For a given power budget, we show that a SR generates less jitter than a DLL when both are realized with Current Mode Logic (CML) circuits and

  1. Acute and phase-shifting effects of ocular and extraocular light in human circadian physiology

    NARCIS (Netherlands)

    Rüger, Melanie; Gordijn, Marijke C.M.; Beersma, Domien G.M.; de Vries, Bonnie; Daan, Serge

    2003-01-01

    Light can influence physiology and performance of humans in two distinct ways. It can acutely change the level of physiological and behavioral parameters, and it can induce a phase shift in the circadian oscillators underlying variations in these levels. Until recently, both effects were thought to

  2. 16-level differential phase shift keying (D16PSK) in direct detection optical communication systems

    DEFF Research Database (Denmark)

    Sambaraju, R.; Tokle, Torger; Jensen, J.B.

    2006-01-01

    Optical 16-level differential phase shift keying (D16PSK) carrying four bits for every symbol is proposed for direct detection optical communication systems. Transmitter and receiver schematics are presented, and the receiver sensitivity is discussed. We numerically investigate the impact...

  3. Simultaneous all-optical AND and NOR gates for NRZ differential phase-shift-keying signals

    DEFF Research Database (Denmark)

    Xu, Jing; Zhang, X.; Dong, J.

    2008-01-01

    A scheme for realizing all-optical logic AND and NOR gates simultaneously for nonreturn-to-zero differential phase-shift-keying signals is proposed and demonstrated based on a delayed interferometer and two semiconductor optical amplifiers. Experimental demonstration at 20 Gb/s verifies the logic...

  4. Low-Jitter Multi-phase Clock Generation: A Comparison between DLLs and Shift Registers

    NARCIS (Netherlands)

    Gao, X.; Klumperink, Eric A.M.; Nauta, Bram

    2007-01-01

    Abstract—This paper shows that, for a given power budget, a shift register based multi-phase clock generator (MPCG) generates less jitter than a delay-locked loop (DLL) equivalent when both are realized with current mode logic (CML) circuits and white noise is assumed. This is due to the factor that

  5. On calculating phase shifts and performing fits to scattering cross sections or transport properties

    International Nuclear Information System (INIS)

    Hepburn, J.W.; Roy, R.J. Le

    1978-01-01

    Improved methods of calculating quantum mechanical phase shifts and for performing least-squares fits to scattering cross sections or transport properties, are described. Their use in a five-parameter fit to experimental differential cross sections reduces the computer time by a factor of 4-7. (Auth.)

  6. Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue

    Science.gov (United States)

    González, C. A.; Lozano, L. M.; Uscanga, M. C.; Silva, J. G.; Polo, S. M.

    2013-04-01

    Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.

  7. Twin-image reduction method for in-line digital holography using periphery and random reference phase-shifting techniques

    Science.gov (United States)

    Oshima, Teppei; Matsudo, Yusuke; Kakue, Takashi; Arai, Daisuke; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2015-09-01

    Digital holography has the twin image problem that unwanted lights (conjugate and direct lights) overlap in the object light in the reconstruction process. As a method for extracting only the object light, phase-shifting digital holography is widely used; however, this method is not applicable for the observation of moving objects, because this method requires the recording of plural holograms. In this study, we propose a twin-image reduction method by combining the "periphery" method with the "random phase-shifting" method. The proposed method succeeded in improving the reconstruction quality, compared to other one-shot recording methods ("parallel phase-shifting digital holography" and "random phase-shifting").

  8. Space-bandwidth extension in parallel phase-shifting digital holography using a four-channel polarization-imaging camera.

    Science.gov (United States)

    Tahara, Tatsuki; Ito, Yasunori; Xia, Peng; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2013-07-15

    We propose a method for extending the space bandwidth (SBW) available for recording an object wave in parallel phase-shifting digital holography using a four-channel polarization-imaging camera. A linear spatial carrier of the reference wave is introduced to an optical setup of parallel four-step phase-shifting interferometry using a commercially available polarization-imaging camera that has four polarization-detection channels. Then a hologram required for parallel two-step phase shifting, which is a technique capable of recording the widest SBW in parallel phase shifting, can be obtained. The effectiveness of the proposed method was numerically and experimentally verified.

  9. Squeezing-enhanced phase-shift-keyed binary communication in noisy channels

    Science.gov (United States)

    Chesi, Giovanni; Olivares, Stefano; Paris, Matteo G. A.

    2018-03-01

    We address binary phase-shift-keyed communication channels based on Gaussian states and prove that squeezing improves state discrimination at fixed energy of the channel, and also in the presence of phase diffusion. We then assess performances of homodyne detection against the ultimate quantum limits to discrimination and show that homodyning achieves optimality in the large-noise regime. Finally, we consider noise in the preparation of the seed signal (before phase encoding) and show that, also in this case, squeezing may improve state discrimination in realistic conditions.

  10. Band-gaps in long Josephson junctions with periodic phase-shifts

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Saeed, E-mail: saeedahmad@uom.edu.pk [Department of Mathematics, University of Malakand Chakdara, Dir(L), Pakhtunkhwa (Pakistan); Susanto, Hadi, E-mail: hsusanto@essex.ac.uk [Department of Mathematical Sciences, University of Essex, Colchester CO4 3SQ (United Kingdom); Wattis, Jonathan A.D. [School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2017-04-04

    We investigate analytically and numerically a long Josephson junction on an infinite domain, having arbitrary periodic phase shift of κ, that is, the so-called 0–κ long Josephson junction. The system is described by a one-dimensional sine-Gordon equation and has relatively recently been proposed as artificial atom lattices. We discuss the existence of periodic solutions of the system and investigate their stability both in the absence and presence of an applied bias current. We find critical values of the phase-discontinuity and the applied bias current beyond which static periodic solutions cease to exist. Due to the periodic discontinuity in the phase, the system admits regions of allowed and forbidden bands. We perturbatively investigate the Arnold tongues that separate the region of allowed and forbidden bands, and discuss the effect of an applied bias current on the band-gap structure. We present numerical simulations to support our analytical results. - Highlights: • A long Josephson junction on an infinite domain having arbitrary periodic phase shift has been proposed as artificial atom lattices recently. • We compute the band-gaps of the system asymptotically. • We show that the phase-shift and applied bias current can be used to control the band structures.

  11. Fuzzy Determination of Target Shifting Time and Torque Control of Shifting Phase for Dry Dual Clutch Transmission

    Directory of Open Access Journals (Sweden)

    Zhiguo Zhao

    2014-01-01

    Full Text Available Based on the independently developed five-speed dry dual clutch transmission (DDCT, the paper proposes the torque coordinating control strategy between engine and two clutches, which obtains engine speed and clutch transferred torque in the shifting process, adequately reflecting the driver intention and improving the shifting quality. Five-degree-of-freedom (DOF shifting dynamics model of DDCT with single intermediate shaft is firstly established according to its physical characteristics. Then the quantitative control objectives of the shifting process are presented. The fuzzy decision of shifting time and the model-based torque coordinating control strategy are proposed and also verified by simulating under different driving intentions in up-/downshifting processes with the DCT model established on the MATLAB/Simulink. Simulation results validate that the shifting control algorithm proposed in this paper can not only meet the shifting quality requirements, but also adapt to the various shifting intentions, having a strong robustness.

  12. Phase-shifted Bragg grating inscription in PMMA microstructured POF using 248 nm UV radiation

    DEFF Research Database (Denmark)

    Pereira, L.; Pospori, A.; Antunes, Paulo

    2017-01-01

    In this work we experimentally validate and characterize the first phase-shifted polymer optical fiber Bragg gratings (PS-POFBGs) produced using a single pulse from a 248 nm krypton fluoride laser. A single-mode poly (methyl methacrylate) optical fiber with a core doped with benzyl dimethyl ketal...... for photosensitivity improvement was used. A uniform phase mask customized for 850 nm grating inscription was used to inscribe these Bragg structures. The phase shift defect was created directly during the grating inscription process by placing a narrow blocking aperture in the center of the UV beam. The produced high......-quality Bragg grating structures, presenting a double dips, reject 16.3 dB (97.6% reflectivity) and 13.2 dB (95.2% reflectivity) of the transmitted power, being therefore appropriate for sensing or other photonic applications. Its transmission spectrum possesses two sharp transmission notches, allowing...

  13. Compression of computer generated phase-shifting hologram sequence using AVC and HEVC

    Science.gov (United States)

    Xing, Yafei; Pesquet-Popescu, Béatrice; Dufaux, Frederic

    2013-09-01

    With the capability of achieving twice the compression ratio of Advanced Video Coding (AVC) with similar reconstruction quality, High Efficiency Video Coding (HEVC) is expected to become the newleading technique of video coding. In order to reduce the storage and transmission burden of digital holograms, in this paper we propose to use HEVC for compressing the phase-shifting digital hologram sequences (PSDHS). By simulating phase-shifting digital holography (PSDH) interferometry, interference patterns between illuminated three dimensional( 3D) virtual objects and the stepwise phase changed reference wave are generated as digital holograms. The hologram sequences are obtained by the movement of the virtual objects and compressed by AVC and HEVC. The experimental results show that AVC and HEVC are efficient to compress PSDHS, with HEVC giving better performance. Good compression rate and reconstruction quality can be obtained with bitrate above 15000kbps.

  14. A coral-algal phase shift in Mesoamerica not driven by changes in herbivorous fish abundance.

    Directory of Open Access Journals (Sweden)

    Jesús Ernesto Arias-González

    Full Text Available Coral-algal phase shifts in which coral cover declines to low levels and is replaced by algae have often been documented on coral reefs worldwide. This has motivated coral reef management responses that include restriction and regulation of fishing, e.g. herbivorous fish species. However, there is evidence that eutrophication and sedimentation can be at least as important as a reduction in herbivory in causing phase shifts. These threats arise from coastal development leading to increased nutrient and sediment loads, which stimulate algal growth and negatively impact corals respectively. Here, we first present results of a dynamic process-based model demonstrating that in addition to overharvesting of herbivorous fish, bottom-up processes have the potential to precipitate coral-algal phase shifts on Mesoamerican reefs. We then provide an empirical example that exemplifies this on coral reefs off Mahahual in Mexico, where a shift from coral to algal dominance occurred over 14 years, during which there was little change in herbivore biomass but considerable development of tourist infrastructure. Our results indicate that coastal development can compromise the resilience of coral reefs and that watershed and coastal zone management together with the maintenance of functional levels of fish herbivory are critical for the persistence of coral reefs in Mesoamerica.

  15. A coral-algal phase shift in Mesoamerica not driven by changes in herbivorous fish abundance.

    Science.gov (United States)

    Arias-González, Jesús Ernesto; Fung, Tak; Seymour, Robert M; Garza-Pérez, Joaquín Rodrigo; Acosta-González, Gilberto; Bozec, Yves-Marie; Johnson, Craig R

    2017-01-01

    Coral-algal phase shifts in which coral cover declines to low levels and is replaced by algae have often been documented on coral reefs worldwide. This has motivated coral reef management responses that include restriction and regulation of fishing, e.g. herbivorous fish species. However, there is evidence that eutrophication and sedimentation can be at least as important as a reduction in herbivory in causing phase shifts. These threats arise from coastal development leading to increased nutrient and sediment loads, which stimulate algal growth and negatively impact corals respectively. Here, we first present results of a dynamic process-based model demonstrating that in addition to overharvesting of herbivorous fish, bottom-up processes have the potential to precipitate coral-algal phase shifts on Mesoamerican reefs. We then provide an empirical example that exemplifies this on coral reefs off Mahahual in Mexico, where a shift from coral to algal dominance occurred over 14 years, during which there was little change in herbivore biomass but considerable development of tourist infrastructure. Our results indicate that coastal development can compromise the resilience of coral reefs and that watershed and coastal zone management together with the maintenance of functional levels of fish herbivory are critical for the persistence of coral reefs in Mesoamerica.

  16. Impact of Signal-Conjugate Wavelength Shift on Optical Phase Conjugation-based Transmission of QAM Signals

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Lillieholm, Mads; Yankov, Metodi Plamenov

    2017-01-01

    The impact of signal-conjugate wavelength shift on nonlinearity compensation through optical phase conjugation is investigated for 64- and 256-QAM. Wavelength-shift independent achievable rate improvements between 0.2 and 0.3 bit/symbol are reported for shifts up to 30 nm in 500-km transmission....

  17. Altered circadian rhythm and metabolic gene profile in rats subjected to advanced light phase shifts.

    Directory of Open Access Journals (Sweden)

    Laura Herrero

    Full Text Available The circadian clock regulates metabolic homeostasis and its disruption predisposes to obesity and other metabolic diseases. However, the effect of phase shifts on metabolism is not completely understood. We examined whether alterations in the circadian rhythm caused by phase shifts induce metabolic changes in crucial genes that would predispose to obesity. Three-month-old rats were maintained on a standard diet under lighting conditions with chronic phase shifts consisting of advances, delays or advances plus delays. Serum leptin, insulin and glucose levels decreased only in rats subjected to advances. The expression of the clock gene Bmal 1 increased in the hypothalamus, white adipose tissue (WAT, brown adipose tissue (BAT and liver of the advanced group compared to control rats. The advanced group showed an increase in hypothalamic AgRP and NPY mRNA, and their lipid metabolism gene profile was altered in liver, WAT and BAT. WAT showed an increase in inflammation and ER stress and brown adipocytes suffered a brown-to-white transformation and decreased UCP-1 expression. Our results indicate that chronic phase advances lead to significant changes in neuropeptides, lipid metabolism, inflammation and ER stress gene profile in metabolically relevant tissues such as the hypothalamus, liver, WAT and BAT. This highlights a link between alteration of the circadian rhythm and metabolism at the transcriptional level.

  18. Carrier-separating demodulation of phase shifting self-mixing interferometry

    Science.gov (United States)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2017-03-01

    A carrier separating method associated with noise-elimination had been introduced into a sinusoidal phase-shifting self-mixing interferometer. The conventional sinusoidal phase shifting self-mixing interferometry was developed into a more competitive instrument with high computing efficiency and nanometer accuracy of λ / 100 in dynamical vibration measurement. The high slew rate electro-optic modulator induced a sinusoidal phase carrier with ultralow insertion loss in this paper. In order to extract phase-shift quickly and precisely, this paper employed the carrier-separating to directly generate quadrature signals without complicated frequency domain transforms. Moreover, most noises were evaluated and suppressed by a noise-elimination technology synthesizing empirical mode decomposition with wavelet transform. The overall laser system was described and inherent advantages such as high computational efficiency and decreased nonlinear errors of the established system were demonstrated. The experiment implemented on a high precision PZT (positioning accuracy was better than 1 nm) and compared with laser Doppler velocity meter. The good agreement of two instruments shown that the short-term resolution had improved from 10 nm to 1.5 nm in dynamic vibration measurement with reduced time expense. This was useful in precision measurement to improve the SMI with same sampling rate. The proposed signal processing was performed in pure time-domain requiring no preprocessing electronic circuits.

  19. Pixel-addressable phase calibration of spatial light modulators: a common-path phase-shifting interferometric microscopy approach

    Science.gov (United States)

    Xia, Jianpei; Chang, Chenliang; Chen, Zhaozhong; Zhu, Zheyuan; Zeng, Tingting; Liang, Pei-Ying; Ding, Jianping

    2017-12-01

    As spatial light modulators (SLMs) are becoming flexible and the preferred device for light steering, the SLM’s modulation calibration still remains challenging. No pixel-addressable measurement of the SLM has yet been practically implemented. We present a quantitative phase measurement and calibration method for a parallel aligned liquid crystal spatial light modulator (PAL-SLM) based on Pancharatnam phase-shifting interferometric microscopy. The pixel-wise phase of SLM can be detected from microscopic interference pattern formed from two orthogonally polarized light waves reflected off the PAL-SLM. The wave phase is modulated or non-modulated depending on its polarization direction parallel or orthogonal to the liquid crystal director. Owing to self-referencing common-path interferometric microscopic imaging, the proposed method is quite robust against environmental disturbance and enables a high-precision pixel-wise characterization of SLM.

  20. Technological research of differential phase shift keying receiver in the satellite-to-ground laser communication

    Science.gov (United States)

    Ma, Xiaoping; Sun, Jianfeng; Zhi, Yanan; Liu, Liren

    2012-10-01

    Laser communication links between satellite and ground remains a bottleneck problem that has not been solved in free space communication network now. Atmospheric disturbances have badly influenced the wave-front of signal light and destroyed the integrality of optical phase, so the bit error rate (BER) is increased at the receiving terminal in the space-to-ground laser communication. With conventional coherent reception, the contrast of coherent light increased dramatically, and transmission efficiency of Space to ground laser communication decreased. Receiving technology based on differential phase shift keying (DPSK) is proposed here to overcome the effects of atmosphere here. Differential phase shift keying without the integrality and compensation of the optical phases, is suited for high rate space to ground communication links due to its immunity of the wavefront of a beam passing atmosphere. A Mach-Zehnder delay interferometer is used for differential delay which is equal to the one bit period. The differential data information can be obtained from the optical phase changes. Differential phase modulation technique can be a promising optical receiving technology.

  1. Phase error compensation for a 3-D shape measurement system based on the phase-shifting method

    Science.gov (United States)

    Zhang, Song; Huang, Peisen S.

    2005-11-01

    This paper describes a novel phase error compensation method for reducing the measurement error caused by non-sinusoidal waveforms in the phase-shifting method. For 3D shape measurement systems using commercial video projectors, the non-sinusoidal nature of the projected fringe patterns as a result of the nonlinear gamma curve of the projectors causes significant phase measurement error and therefore shape measurement error. The proposed phase error compensation method is based on our finding that the phase error due to the non-sinusoidal waveform of the fringe patterns depends only on the nonlinearity of the projector's gamma curve. Therefore, if the projector's gamma curve is calibrated and the phase error due to the nonlinearity of the gamma curve is calculated, a look-up-table (LUT) that stores the phase error can be constructed for error compensation. Our experimental results demonstrate that by using the proposed method, the measurement error can be reduced by 10 times. In addition to phase error compensation, a similar method is also proposed to correct the nonsinusoidality of the fringe patterns for the purpose of generating a more accurate flat image of the object for texture mapping. While not relevant to applications in metrology, texture mapping is important for applications in computer vision and computer graphics.

  2. Study of key technology of ghost imaging via compressive sensing for a phase object based on phase-shifting digital holography

    International Nuclear Information System (INIS)

    Leihong, Zhang; Dong, Liang; Bei, Li; Zilan, Pan; Dawei, Zhang; Xiuhua, Ma

    2015-01-01

    In this article, the algorithm of compressing sensing is used to improve the imaging resolution and realize ghost imaging via compressive sensing for a phase object based on the theoretical analysis of the lensless Fourier imaging of the algorithm of ghost imaging based on phase-shifting digital holography. The algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography uses the bucket detector to measure the total light intensity of the interference and the four-step phase-shifting method is used to obtain the total light intensity of differential interference light. The experimental platform is built based on the software simulation, and the experimental results show that the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography can obtain the high-resolution phase distribution figure of the phase object. With the same sampling times, the phase clarity of the phase distribution figure obtained by the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography is higher than that obtained by the algorithm of ghost imaging based on phase-shift digital holography. In this article, this study further extends the application range of ghost imaging and obtains the phase distribution of the phase object. (letter)

  3. Self-correction of projector nonlinearity in phase-shifting fringe projection profilometry.

    Science.gov (United States)

    Lü, Fuxing; Xing, Shuo; Guo, Hongwei

    2017-09-01

    In phase-shifting fringe projection profilometry, the luminance nonlinearity of the used projector has been recognized as one of the most crucial factors decreasing the measurement accuracy. To solve this problem, this paper presents a self-correcting technique that allows us to suppress the effect of the projector nonlinearity in the absence of any calibration data regarding the projector intensities or regarding the phase errors. In its first step, the standard phase-shifting algorithm is used to recover the phases, as well as the background intensities and the modulations. Using these results enables normalizing the fringe patterns, for ridding them of the effects of the background and modulations. Second, we smooth the calculated phase map by use of a low-pass filter in order to remove the ripple-like phase errors induced by the projector nonlinearity. Third, we determine a polynomial representing the projector nonlinearity by fitting the curve of the normalized fringe intensities against the cosine values of the smoothed phases. Finally, we correct the phase errors using the curve just obtained. Doing these steps in an iterative way eventually results in a phase map and, further, a 3D shape with their artifacts induced by the projector nonlinearity suppressed significantly. Experimental results demonstrate that this technique offers some advantages over others. It does not require a prior calibration of the projector, thus being suitable for dealing with a time-variant nonlinearity; its pointwise operation protects the edges and details of the measurement results from being blurred; and it works well with very few fringe patterns and is efficient in image capturing.

  4. An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

    International Nuclear Information System (INIS)

    Park, S. J.; Hong, Y. J.; Kim, H. B.; Son, H. K.; Yu, B. K.

    2002-01-01

    The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance

  5. Wavelength modulation in a two-window common path interferometer for phase-shifting

    Science.gov (United States)

    Rivera-Ortega, Uriel

    2018-02-01

    A novel and simple method for phase-shifting under the scheme of a two-window 4 f common path interferometer configuration with a binary grating at the Fourier plane is proposed. The proposal is based on periodicity variations of the grating grooves in the frequency space, which is emulated in an experimental implementation by changing the wavelength of a tunable laser diode used as the light source. Because of the common path configuration, it is expected to diminish errors due to undesired vibrations and optical aberrations. The viability of the proposal will be sustained with simulated and experimental, which include phase-shifted interferograms and reconstructed wavefronts. Due to the characteristics of the proposed experimental setup, it can be easily replicated and automated.

  6. Terahertz filter with tailored passband using multiple phase shifted fiber Bragg gratings.

    Science.gov (United States)

    Zhou, Shu Fan; Reekie, Laurence; Chan, Hau Ping; Luk, Kwai Man; Chow, Yuk Tak

    2013-02-01

    Transmission filters for the terahertz domain having a shaped bandpass have been modeled and demonstrated. The filter designs were based on the desired filter type and bandwidth, and implemented by cascading quarter wave phase shifted fiber Bragg gratings written in Topas polymer subwavelength fiber. As an example, a 5-pole Chebyshev filter with <3 GHz bandwidth was designed and fabricated. Experimental and simulated results are in good agreement.

  7. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    Science.gov (United States)

    Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

    2018-03-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

  8. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    DEFF Research Database (Denmark)

    Min, Rui; Marques, Carlos; Bang, Ole

    2018-01-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...... periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured....

  9. Comments on some uncertainties in determination of π-π phase shifts

    International Nuclear Information System (INIS)

    MacNaughton, J.

    1992-01-01

    Some general remarks are made about the difficulties of phase shift analysis of πN→πN reactions, however the results of such analyses are now well established. Some comparison is made with more complicated final states. Many difficulties with one pion exchange studies are listed, many of which are well known. Polarization experiments are discussed very briefly, and some discussion is given of possible multichannel effects-diffractive dissociation in particular. Finally some dreams are listed. (author)

  10. Phase-Shift Cyclic-Delay Diversity for MIMO OFDM Systems

    Directory of Open Access Journals (Sweden)

    Young-Han Nam

    2010-01-01

    Full Text Available Phase-shift cyclic-delay diversity (PS CDD scheme and space-frequency-block-code (SFBC PS CDD are developed for multiple-input-multiple-output (MIMO orthogonal frequency division multiplexing (OFDM systems. The proposed PS CDD scheme preserves the diversity advantage of traditional CDD in uncorrelated multiantenna channels, and furthermore removes frequency-selective nulling problem of the traditional CDD in correlated multiantenna channels.

  11. Phase shifts and the second virial coefficient for a partially ionized hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Omarbakiyeva, Y.A. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); IETP, al-Farabi Kazakh National University, 96a Tole bi str., 050012 Almaty (Kazakhstan); Roepke, G. [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany); Ramazanov, T.S. [IETP, al-Farabi Kazakh National University, 96a Tole bi str., 050012 Almaty (Kazakhstan)

    2009-12-15

    The influence of the interaction of electrons with hydrogen atoms on the thermodynamical properties of dense plasmas is investigated using a virial expansion approach. The second virial coefficient for the electron-atom interaction is obtained from the Beth-Uhlenbeck formula. Elastic scattering phase shifts are calculated with the help of the phase function method for different polarization potential models. Results for the second virial coefficient are given that take into account both the bound state part and the scattering state contribution (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Bandpass transmission filters based on phase shifted fiber Bragg gratings in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Ortega, Beatriz; Min, Rui; Sáez-Rodri­guez, David

    2017-01-01

    In this contribution we report on the fabrication of novel bandpass transmission filters based on PS-FBGs in microstructured polymer fibers at telecom wavelengths. The phase mask technique is employed to fabricate several superimposed gratings with slight different periods in order to form Moir......é structures with a single or various π phase shifts along the device. Simulations and experimental results are included in order to demonstrate very narrowband transmission filters. Experimental characterization under strain and temperature variations is provided in a non-annealed fiber and time stability...... of the fabricated devices has been also measured under different pre-strain conditions....

  13. The exergy of a phase shift: Ecosystem functioning loss in seagrass meadows of the Mediterranean Sea

    Science.gov (United States)

    Montefalcone, Monica; Vassallo, Paolo; Gatti, Giulia; Parravicini, Valeriano; Paoli, Chiara; Morri, Carla; Bianchi, Carlo Nike

    2015-04-01

    Sustained functioning of ecosystems is predicted to depend upon the maintenance of their biodiversity, structure and integrity. The large consensus achieved in this regard, however, faces to the objective difficulty of finding appropriate metrics to measure ecosystem functioning. Here, we aim at evaluating functional consequence of the phase shift occurring in meadows of the Mediterranean seagrass Posidonia oceanica, a priority habitat that is undergoing regression in many coastal areas due to multiple human pressures. Structural degradation of the P. oceanica ecosystem, consequent to increasing coastal exploitation and climate change, may result in the progressive replacement of this seagrass by opportunistic macrophytes, either native or alien. Reviewing published information and our personal records, we measured changes in biological habitat provisioning, species richness and biomass associated to each of the alternative states characterizing the phase shift. Then, ecosystem functioning was assessed by computing the exergy associated to each state, exergy being a state variable that measures the ecosystem capacity to produce work. Phase shift was consistently shown to imply loss in habitat provision, species richness, and biomass; structural and compositional loss was parallelled by a reduction of exergy content, thus providing for the first time an objective and integrative measure of the loss of ecosystem functioning following the degradation of healthy seagrass meadows.

  14. All-optical simultaneous multichannel quadrature phase shift keying signal regeneration based on phase-sensitive amplification

    Science.gov (United States)

    Wang, Hongxiang; Wang, Qi; Bai, Lin; Ji, Yuefeng

    2018-01-01

    A scheme is proposed to realize the all-optical phase regeneration of four-channel quadrature phase shift keying (QPSK) signal based on phase-sensitive amplification. By utilizing conjugate pump and common pump in a highly nonlinear optical fiber, degenerate four-wave mixing process is observed, and QPSK signals are regenerated. The number of waves is reduced to decrease the cross talk caused by undesired nonlinear interaction during the coherent superposition process. In addition, to avoid the effect of overlapping frequency, frequency spans between pumps and signals are set to be nonintegral multiples. Optical signal-to-noise ratio improvement is validated by bit error rate measurements. Compared with single-channel regeneration, multichannel regeneration brings 0.4-dB OSNR penalty when the value of BER is 10-3, which shows the cross talk in regeneration process is negligible.

  15. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

    Science.gov (United States)

    Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A

    2016-02-26

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

  16. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  17. Balancing the electric mode by shifting with time of one-phase electric receiver load graphs

    Directory of Open Access Journals (Sweden)

    Леонід Борисович Терешкевич

    2017-07-01

    Full Text Available A method for balancing the electrical mode by shifting the load diagrams of single-phase electric receivers in time has been developed, that does not require additional capital investments for its implementation, does not affect the technological process and, in certain cases, does not reduce the products output. The method is believed, on the basis of the information on the load curves of single-phase electric receivers connected to one node of the electrical network, to evaluate the mode asymmetry in the supplying three-wire line with all possible relative temporal shifts of the graphs. The criterion for choosing the optimal variant is additional losses of active energy in the supply line due to the asymmetry of the mode. To do this, a set of negative sequence current matrices generated by electric receivers is formed, with the number of rows equal to the number of stages of the load curve, and the number of columns is the tripled number of single-phase power receivers. The total number of matrices is equal to the number of variants of shifts of graphs relative to any of the steps of one of them. The realized connection of electric receivers to the network is described in Boolean variables and is represented by a vector with the number of elements equal to three times the number of electric receivers. To estimate the effect of implementing any variant of the shifts, one can multiply the corresponding matrix of negative sequence currents by the connection vector, and to process the obtained result then. All work on the synthesis of matrices, calculations and selection of the optimal variant is algorithmized, which makes it possible to use information technologies for decision making. The effectiveness of the developed method is illustrated by a numerical example

  18. Phase manipulation of Goos–Hänchen shifts in a single-layer of graphene nanostructure under strong magnetic field

    Science.gov (United States)

    Solookinejad, Gh; Jabbari, M.; Panahi, M.; Ahmadi Sangachin, E.

    2017-11-01

    In this paper, we discuss the phase management of Goos–Hänchen (GH) shifts of a probe light through a cavity with a single-layer graphene nanostructure under a strong magnetic field. By using the quantum mechanical density matrix formalism we study the GH shifts of reflected and transmitted light beams. It is realized that negative or positive GH shifts can be achieved simultaneously by tuning some controllable parameters such as relative phase and the Rabi frequency of the applied fields. Moreover, the thickness effect of the cavity structure is considered as an effective parameter for adjusting the GH shifts of reflected and transmitted light beams. We find that by choosing suitable parameters, a maximum negative shift of 4.5 mm and positive shift of 5.4 mm are possible for GH shifts in reflected and transmitted light. Our proposed model may be useful for developing all-optical devices in the infrared region.

  19. Spectral phase shift and residual angular dispersion of an accousto-optic programme dispersive filter

    International Nuclear Information System (INIS)

    Boerzsoenyi, A.; Meroe, M.

    2010-01-01

    Complete text of publication follows. There is an increasing demand for active and precise dispersion control of ultrashort laser pulses. In chirped pulse amplification (CPA) laser systems, the dispersion of the optical elements of the laser has to be compensated at least to the fourth order to obtain high temporal contrast compressed pulses. Nowadays the most convenient device for active and programmable control of spectral phase and amplitude of broadband laser pulses is the acousto-optic programmable dispersive filter (AOPDF), claimed to be able to adjust the spectral phase up to the fourth order. Although it has been widely used, surprisingly enough there has been only a single, low resolution measurement reported on the accuracy of the induced spectral phase shift of the device. In our paper we report on the first systematic experiment aiming at the precise characterization of an AOPDF device. In the experiment the spectral phase shift of the AOPDF device was measured by spectrally and spatially resolved interferometry, which is especially powerful tool to determine small dispersion values with high accuracy. Besides the spectral phase dispersion, we measured both the propagation direction angular dispersion (PDAD) and the phase front angular dispersion (PhFAD). Although the two quantities are equal for plane waves, there may be noticeable difference for Gaussian pulses. PDAD was determined simply by focusing the beam on the slit of an imaging spectrograph, while PhFAD was measured by the use of an inverted Mach-Zehnder interferometer and an imaging spectrograph. In the measurements, the spectral phase shift and both types of angular dispersion have been recorded upon the systematic change of all the accessible functions of the acousto-optic programmable dispersive filter. The measured values of group delay dispersion (GDD) and third order dispersion (TOD) have been found to agree with the preset values within the error of the measurement (1 fs 2 and 10 fs 3

  20. Regional fringe analysis for improving depth measurement in phase-shifting fringe projection profilometry

    Science.gov (United States)

    Chien, Kuang-Che Chang; Tu, Han-Yen; Hsieh, Ching-Huang; Cheng, Chau-Jern; Chang, Chun-Yen

    2018-01-01

    This study proposes a regional fringe analysis (RFA) method to detect the regions of a target object in captured shifted images to improve depth measurement in phase-shifting fringe projection profilometry (PS-FPP). In the RFA method, region-based segmentation is exploited to segment the de-fringed image of a target object, and a multi-level fuzzy-based classification with five presented features is used to analyze and discriminate the regions of an object from the segmented regions, which were associated with explicit fringe information. Then, in the experiment, the performance of the proposed method is tested and evaluated on 26 test cases made of five types of materials. The qualitative and quantitative results demonstrate that the proposed RFA method can effectively detect the desired regions of an object to improve depth measurement in the PS-FPP system.

  1. Shifts and Splittings of the Hole Bands in the Nematic Phase of FeSe

    Science.gov (United States)

    Watson, Matthew D.; Haghighirad, Amir A.; Takita, Hitoshi; Mansuer, Wumiti; Iwasawa, Hideaki; Schwier, Eike F.; Ino, Akihiro; Hoesch, Moritz

    2017-05-01

    We report a high-resolution laser-based angle-resolved photoemission spectroscopy (laser-ARPES) study of single crystals of FeSe, focusing on the temperature-dependence of the hole-like bands around the Γ point. As the system cools through the tetragonal-orthorhombic "nematic" structural transition at 90 K, the splitting of the dxz/dyz bands is observed to increase by a magnitude of 13 meV. Moreover, the onset of a ˜10 meV downward shift of the dxy band is also observed at 90 K. These measurements provide clarity on the nature, magnitude and temperature-dependence of the band shifts at the Γ point in the nematic phase of FeSe.

  2. Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

    Science.gov (United States)

    Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-06-15

    Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

  3. Equivalence principle for quantum systems: dephasing and phase shift of free-falling particles

    Science.gov (United States)

    Anastopoulos, C.; Hu, B. L.

    2018-02-01

    We ask the question of how the (weak) equivalence principle established in classical gravitational physics should be reformulated and interpreted for massive quantum objects that may also have internal degrees of freedom (dof). This inquiry is necessary because even elementary concepts like a classical trajectory are not well defined in quantum physics—trajectories originating from quantum histories become viable entities only under stringent decoherence conditions. From this investigation we posit two logically and operationally distinct statements of the equivalence principle for quantum systems. Version A: the probability distribution of position for a free-falling particle is the same as the probability distribution of a free particle, modulo a mass-independent shift of its mean. Version B: any two particles with the same velocity wave-function behave identically in free fall, irrespective of their masses. Both statements apply to all quantum states, including those without a classical correspondence, and also for composite particles with quantum internal dof. We also investigate the consequences of the interaction between internal and external dof induced by free fall. For a class of initial states, we find dephasing occurs for the translational dof, namely, the suppression of the off-diagonal terms of the density matrix, in the position basis. We also find a gravitational phase shift in the reduced density matrix of the internal dof that does not depend on the particle’s mass. For classical states, the phase shift has a natural classical interpretation in terms of gravitational red-shift and special relativistic time-dilation.

  4. Two-level image authentication by two-step phase-shifting interferometry and compressive sensing

    Science.gov (United States)

    Zhang, Xue; Meng, Xiangfeng; Yin, Yongkai; Yang, Xiulun; Wang, Yurong; Li, Xianye; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2018-01-01

    A two-level image authentication method is proposed; the method is based on two-step phase-shifting interferometry, double random phase encoding, and compressive sensing (CS) theory, by which the certification image can be encoded into two interferograms. Through discrete wavelet transform (DWT), sparseness processing, Arnold transform, and data compression, two compressed signals can be generated and delivered to two different participants of the authentication system. Only the participant who possesses the first compressed signal attempts to pass the low-level authentication. The application of Orthogonal Match Pursuit CS algorithm reconstruction, inverse Arnold transform, inverse DWT, two-step phase-shifting wavefront reconstruction, and inverse Fresnel transform can result in the output of a remarkable peak in the central location of the nonlinear correlation coefficient distributions of the recovered image and the standard certification image. Then, the other participant, who possesses the second compressed signal, is authorized to carry out the high-level authentication. Therefore, both compressed signals are collected to reconstruct the original meaningful certification image with a high correlation coefficient. Theoretical analysis and numerical simulations verify the feasibility of the proposed method.

  5. Stress Analysis of an Edge-Cracked Plate by using Photoelastic Fringe Phase Shifting Method

    International Nuclear Information System (INIS)

    Baek, Tae Hyun; Kim, Myung Soo; Cho, Sung Ho

    2000-01-01

    The method of photoelasticity allows one to obtain principal stress differences and principal stress directions in a photoelastic model. In the classical approach, the photoelastic parameters are measured manually point by point. The previous methods require much time and skill in the identification and measurement of photoelastic data. Fringe phase shifting method has been recently developed and widely used to measure and analyze fringe data in photo-mechanics. This paper presents the test results of photoelastic fringe phase shifting technique for the stress analysis of a circular disk under compression and an edge-cracked plate subjected to tensile load. The technique used here requires four phase stepped photoelastic images obtained from a circular polariscope by rotating the analyzer at 0 .deg. ,45 .deg. ,90 .deg. ,and 135 .deg. . Experimental results are compared with those or FEM. Good agreement between the results can be observed. However, some error may be included if the technique is used to general direction which is not parallel to isoclinic fringe

  6. Detection of Cerebral Hemorrhage in Rabbits by Time-Difference Magnetic Inductive Phase Shift Spectroscopy

    Science.gov (United States)

    Pan, Wencai; Yan, Qingguang; Qin, Mingxin; Jin, Gui; Sun, Jian; Ning, Xu; Zhuang, Wei; Peng, Bin; Li, Gen

    2015-01-01

    Cerebral hemorrhage, a difficult issue in clinical practice, is often detected and studied with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). However, these expensive devices are not readily available in economically underdeveloped regions, and hence are unable to provide bedside and emergency on-site monitoring. The magnetic inductive phase shift (MIPS) is an emerging technology that may become a new tool to detect cerebral hemorrhage and to serve as an inexpensive partial substitute to medical imaging. In order to study a wider band of cerebral hemorrhage MIPS and to provide more useful information for measuring cerebral hemorrhage, we established a cerebral hemorrhage magnetic induction phase shift spectroscopy (MIPSS) detection system. Thirteen rabbits with five cerebral hemorrhage states were studied using a single coil-coil within a 1 MHz-200 MHz frequency range in linear sweep. A feature band (FB) with the highest detection sensitivity and the greatest stability was selected for further analysis and processing. In addition, a maximum conductivity cerebrospinal fluid (CSF) MRI was performed to verify and interpret the MIPSS result. The average phase shift change induced by a 3 ml injection of autologous blood under FB was -7.7503° ± 1.4204°, which was considerably larger than our previous work. Data analysis with a non-parametric statistical Friedman M test showed that in the FB, MIPSS could distinguish the five states of cerebral hemorrhage in rabbits, with a statistical significance of phemorrhage severity from a single set of measurements. The results illustrate that the MIPSS detection method is able to provide a new possibility for real-time monitoring and diagnosis of the severity of cerebral hemorrhage. PMID:26001112

  7. Effects of hard mask etch on final topography of advanced phase shift masks

    Science.gov (United States)

    Hortenbach, Olga; Rolff, Haiko; Lajn, Alexander; Baessler, Martin

    2017-07-01

    Continuous shrinking of the semiconductor device dimensions demands steady improvements of the lithographic resolution on wafer level. These requirements challenge the photomask industry to further improve the mask quality in all relevant printing characteristics. In this paper topography of the Phase Shift Masks (PSM) was investigated. Effects of hard mask etch on phase shift uniformity and mask absorber profile were studied. Design of experiments method (DoE) was used for the process optimization, whereas gas composition, bias power of the hard mask main etch and bias power of the over-etch were varied. In addition, influence of the over-etch time was examined at the end of the experiment. Absorber depth uniformity, sidewall angle (SWA), reactive ion etch lag (RIE lag) and through pitch (TP) dependence were analyzed. Measurements were performed by means of Atomic-force microscopy (AFM) using critical dimension (CD) mode with a boot-shaped tip. Scanning electron microscope (SEM) cross-section images were prepared to verify the profile quality. Finally CD analysis was performed to confirm the optimal etch conditions. Significant dependence of the absorber SWA on hard mask (HM) etch conditions was observed revealing an improvement potential for the mask absorber profile. It was found that hard mask etch can leave a depth footprint in the absorber layer. Thus, the etch depth uniformity of hard mask etch is crucial for achieving a uniform phase shift over the active mask area. The optimized hard mask etch process results in significantly improved mask topography without deterioration of tight CD specifications.

  8. Quadrature phase shift keying coherent state discrimination via a hybrid receiver

    DEFF Research Database (Denmark)

    Müller, C. R.; Castaneda, Mario A. Usuga; Wittmann, C.

    2012-01-01

    We propose and experimentally demonstrate a near-optimal discrimination scheme for the quadrature phase shift keying (QPSK) protocol. We show in theory that the performance of our hybrid scheme is superior to the standard scheme—heterodyne detection—for all signal amplitudes and underpin the pred...... the predictions with our experimental results. Furthermore, our scheme provides hitherto the best performance in the domain of highly attenuated signals. The discrimination is composed of a quadrature measurement, a conditional displacement and a threshold detector....

  9. Analysis of all-optical temporal integrator employing phased-shifted DFB-SOA.

    Science.gov (United States)

    Jia, Xin-Hong; Ji, Xiao-Ling; Xu, Cong; Wang, Zi-Nan; Zhang, Wei-Li

    2014-11-17

    All-optical temporal integrator using phase-shifted distributed-feedback semiconductor optical amplifier (DFB-SOA) is investigated. The influences of system parameters on its energy transmittance and integration error are explored in detail. The numerical analysis shows that, enhanced energy transmittance and integration time window can be simultaneously achieved by increased injected current in the vicinity of lasing threshold. We find that the range of input pulse-width with lower integration error is highly sensitive to the injected optical power, due to gain saturation and induced detuning deviation mechanism. The initial frequency detuning should also be carefully chosen to suppress the integration deviation with ideal waveform output.

  10. ππ-scattering in the quark confinement model. Phase shifts

    International Nuclear Information System (INIS)

    Efimov, G.V.; Ivanov, M.A.; Mashnik, S.G.

    1989-01-01

    The low-energy ππ-scattering is investigated in the Quark Confinement Model (QCM). The four-quark diagrams and the vector (ρ) and scalar (f 0 and ε) meson exchanges are taken into account. The scalar meson problem is discussed. The joint analysis of the decay f 0 →ππ width, s-wave lengths and phase shifts of the ππ-scattering indicates the existence of the broad scalar ε(700-800)-resonance with Γ ε→ππ ≥m ε . The obtained results are in satisfactory agreement with experimental data. 66 refs.; 13 figs.; 2 tabs

  11. The phase shift hypothesis for the circadian component of winter depression.

    Science.gov (United States)

    Lewy, Alfred J; Rough, Jennifer N; Songer, Jeannine B; Mishra, Neelam; Yuhas, Krista; Emens, Jonathan S

    2007-01-01

    The finding that bright light can suppress melatonin production led to the study of two situations, indeed, models, of light deprivation: totally blind people and winter depressives. The leading hypothesis for winter depression (seasonal affective disorder, or SAD) is the phase shift hypothesis (PSH). The PSH was recently established in a study in which SAD patients were given low-dose melatonin in the afternoon/evening to cause phase advances, or in the morning to cause phase delays, or placebo. The prototypical phase-delayed patient, as well as the smaller subgroup of phase-advanced patients, optimally responded to melatonin given at the correct time. Symptom severity improved as circadian misalignment was corrected. Circadian misalignment is best measured as the time interval between the dim light melatonin onset (DLMO) and mid-sleep. Using the operational definition of the plasma DLMO as the interpolated time when melatonin levels continuously rise above the threshold of 10 pg/mL, the average interval between DLMO and mid-sleep in healthy controls is 6 hours, which is associated with optimal mood in SAD patients.

  12. Reconfigurable optical differential phase-shift-keying pattern recognition based on incoherent photonic processing.

    Science.gov (United States)

    Malacarne, Antonio; Ashrafi, Reza; Park, Yongwoo; Azaña, José

    2011-11-01

    We propose and experimentally demonstrate asynchronous optical differential phase-shift-keying (DPSK) pattern recognition using a fully reconfigurable technique. The proposed method uses optical phase-to-bipolar intensity conversion through all-optical differentiation in conjunction with an incoherent time-spectrum convolution system where the pattern to be recognized is implemented directly in the spectral domain through optical amplitude-only linear filtering. Full reconfigurability in terms of bit rate, pattern sequence, and pattern length is achieved using electronically programmable optical filters. We demonstrate dynamically switching recognition of different 64 bit patterns in a continuous 12 Gb/s DPSK pseudorandom optical bit stream with contrast ratio up to 3.8 dB.

  13. Highly birefringent phase-shifted fiber Bragg gratings inscribed with femtosecond laser.

    Science.gov (United States)

    He, Jun; Wang, Yiping; Liao, Changrui; Wang, Qiaoni; Yang, Kaiming; Sun, Bing; Yin, Guolu; Liu, Shen; Zhou, Jiangtao; Zhao, Jing

    2015-05-01

    We demonstrate a highly birefringent phase-shifted fiber Bragg grating (PS-FBG) inscribed in H2-free fiber with a near-infrared femtosecond Gaussian laser beam and uniform phase mask. The PS-FBG was fabricated from an ordinary fiber Bragg grating (FBG) in a case in which overexposure was applied. The spectral evolution from FBG to FS-FBG was observed experimentally with a decrease in transmission loss at dip wavelength, blueshift of the dip wavelength, decrease in the cladding mode loss, and an increase in the insertion loss. A high birefringence was demonstrated experimentally with the existence of PS-FBG only in TM polarization. The formation of the PS-FBG may be due to a negative index change induced by the higher intensity in the center of the Gaussian laser beam.

  14. Intensity error correction for 3D shape measurement based on phase-shifting method

    Science.gov (United States)

    Chung, Tien-Tung; Shih, Meng-Hung

    2011-12-01

    3D shape measurement based on structured light system is a field of ongoing research for the past two decades. For 3D shape measurement using commercial projector and digital camera, the nonlinear gamma of the projector and the nonlinear response of the camera cause the captured fringes having both intensity and phase errors, and result in large measurement shape error. This paper presents a simple intensity error correction process for the phase-shifting method. First, a white flat board is projected with sinusoidal fringe patterns, and the intensity data is extracted from the captured image. The intensity data is fitted to an ideal sine curve. The difference between the captured curve and the fitted sine curve are used to establish an intensity look-up table (LUT). The LUT is then used to calibrate the intensities of measured object images for establishing 3D object shapes. Research results show that the measurement quality of the 3D shapes is significantly improved.

  15. Visualizing the phenomena of wave interference, phase-shifting and polarization by interactive computer simulations

    Science.gov (United States)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2015-09-01

    In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.

  16. Analytical study of nonlinear phase shift through stimulated Brillouin scattering in single mode fiber with the pump power recycling technique

    International Nuclear Information System (INIS)

    Al-Asadi, H A; Mahdi, M A; Bakar, A A A; Adikan, F R Mahamd

    2011-01-01

    We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5 km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30 mW

  17. Stimulated phase-shift acoustic nanodroplets enhance vancomycin efficacy against methicillin-resistant Staphylococcus aureus biofilms

    Directory of Open Access Journals (Sweden)

    Guo H

    2017-06-01

    Full Text Available Hao Guo,1 Ziming Wang,1 Quanyin Du,1 Pan Li,2 Zhigang Wang,2 Aimin Wang1 1Department of Orthopedics, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China; 2Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging, Second Affiliated Hospital of Chongqing Medical University, Chongqing, China Purpose: Bacterial biofilms on the surface of prostheses are becoming a rising concern in managing prosthetic joint infections. The inherent resistant features of biofilms render traditional antimicrobial therapy unproductive and revision surgery outcomes uncertain. This situation has prompted the exploration of novel antimicrobial strategies. The synergy of ultrasound microbubbles and vancomycin has been proposed as an efficient alternative for biofilm eradication. The purpose of this study was to evaluate the anti-biofilm effect of stimulated phase-shift acoustic nanodroplets (NDs combined with vancomycin.Materials and methods: We fabricated lipid phase-shift NDs with a core of liquid perfluoropentane. A new phase change mode for NDs incorporating an initial unfocused low-intensity pulsed ultrasound for 5 minutes and a subsequent incubation at 37°C into a 24-hour duration was developed. Methicillin-resistant Staphylococcus aureus (MRSA biofilms were incubated with vancomycin and NDs under the hybrid stimulation. Biofilm morphology following treatment was determined using confocal laser scanning microscopy and scanning electron microscopy. Resazurin assay was used to quantify bactericidal efficacy against MRSA biofilm bacteria.Results: NDs treated sequentially with ultrasound and heating at 37°C achieved gradual and substantial ND vaporization and cavitation in a successive process. NDs after stimulation were capable of generating stronger destruction on biofilm structure which was best characterized by residual circular arc margins and more dead bacteria. Furthermore, NDs

  18. Ultrahigh-frequency microwave phase shifts mediated by ultrafast dynamics in quantum-dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2010-01-01

    We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers.......We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers....

  19. Analysis of an effective optical filtering technique to enhance microwave phase shifts based on slow and fast light effects

    DEFF Research Database (Denmark)

    Chen, Yaohui; Öhman, Filip; Xue, Weiqi

    2008-01-01

    We theoretically analyze and interpret an effective mechanism, which employs optical filtering to enhance the microwave phase shift that can be achieved in semiconductor optical amplifiers based on slow and fast light effects.......We theoretically analyze and interpret an effective mechanism, which employs optical filtering to enhance the microwave phase shift that can be achieved in semiconductor optical amplifiers based on slow and fast light effects....

  20. Development of an i-line attenuated phase shift process for dual inlay interconnect lithography

    Science.gov (United States)

    Sturtevant, John L.; Ho, Benjamin C. P.; Geiszler, Vincent C.; Herrick, Matthew T.; King, Charles F.; Carter, Russell L.; Roman, Bernard J.; Litt, Lloyd C.; Smith, Brad; Strozewski, Kirk J.

    2000-06-01

    The transition from aluminum/oxide to copper/low-k dielectric interconnect technology involves a variety of fundamental changes in the back-end manufacturing process. The most attractive patterning strategy involves the use of a so-called dual inlay approach, which offers lower fabrication costs by the elimination of one inter-level dielectric (ILD) deposition and polish sequence per metal layer. In this paper, the lithographic challenges for dual inlay, including thin-film interference effect, resist bulk effect, and optical proximity effects are reviewed. The use of attenuated phase shift (aPSM) reticles for patterning vias and trenches was investigated, and shown to provide adequate process margin by optimizing the photoresist and exposure tool parameters. Our results indicate that using appropriately sized attenuated phase shift technique increases the photospeed considerably and simultaneously improves the common process window with sufficient sidelobe suppression margin. The cost of ownership tradeoffs between an attenuated PSM I-Line process and a DUV binary process are discussed.

  1. Full-field stress determination in photoelasticity with phase shifting technique

    Science.gov (United States)

    Guo, Enhai; Liu, Yonggang; Han, Yongsheng; Arola, Dwayne; Zhang, Dongsheng

    2018-04-01

    Photoelasticity is an effective method for evaluating the stress and its spatial variations within a stressed body. In the present study, a method to determine the stress distribution by means of phase shifting and a modified shear-difference is proposed. First, the orientation of the first principal stress and the retardation between the principal stresses are determined in the full-field through phase shifting. Then, through bicubic interpolation and derivation of a modified shear-difference method, the internal stress is calculated from the point with a free boundary along its normal direction. A method to reduce integration error in the shear difference scheme is proposed and compared to the existing methods; the integration error is reduced when using theoretical photoelastic parameters to calculate the stress component with the same points. Results show that when the value of Δx/Δy approaches one, the error is minimum, and although the interpolation error is inevitable, it has limited influence on the accuracy of the result. Finally, examples are presented for determining the stresses in a circular plate and ring subjected to diametric loading. Results show that the proposed approach provides a complete solution for determining the full-field stresses in photoelastic models.

  2. Phase-shifted fiber Bragg grating inscription by fusion splicing technique and femtosecond laser

    Science.gov (United States)

    Jiang, Yajun; Yuan, Yuan; Xu, Jian; Yang, Dexing; Li, Dong; Wang, Meirong; Zhao, Jianlin

    2016-11-01

    A new method for phase-shifted fiber Bragg grating (PS-FBG) inscription in single mode fiber by fusion splicing technique and femtosecond laser is presented. The PS-FBG is produced by exposing the fusion spliced fiber with femtosecond laser through a uniform phase mask. The transmission spectrum of the PS-FBG shows a nonlinear red shift during the inscription process, and two or three main dips can be observed due to the formation of one or two FBG-based Fabry-Pérot structures by controlling the exposure intensity and time of the laser. For a peak power density of 4.8×1013 W/cm2, the induced refractive index modulation can reach to 6.3×10-4 in the fiber without sensitization. The PS-FBG's temperature, strain and pressure characteristics are also experimentally studied. These PS-FBGs can be potentially used for multiple wavelength fiber lasers, filters and optical fiber sensors.

  3. Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology

    Directory of Open Access Journals (Sweden)

    Vasa Radonić

    2017-04-01

    Full Text Available In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor’s operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene–methanol mixture where various concentrations of toluene were analysed.

  4. Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology.

    Science.gov (United States)

    Radonić, Vasa; Birgermajer, Slobodan; Kitić, Goran

    2017-04-18

    In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG) sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor's operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG) structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM) 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene-methanol mixture where various concentrations of toluene were analysed.

  5. Phase shifts, herbivory, and the resilience of coral reefs to climate change.

    Science.gov (United States)

    Hughes, Terence P; Rodrigues, Maria J; Bellwood, David R; Ceccarelli, Daniela; Hoegh-Guldberg, Ove; McCook, Laurence; Moltschaniwskyj, Natalie; Pratchett, Morgan S; Steneck, Robert S; Willis, Bette

    2007-02-20

    Many coral reefs worldwide have undergone phase shifts to alternate, degraded assemblages because of the combined effects of over-fishing, declining water quality, and the direct and indirect impacts of climate change. Here, we experimentally manipulated the density of large herbivorous fishes to test their influence on the resilience of coral assemblages in the aftermath of regional-scale bleaching in 1998, the largest coral mortality event recorded to date. The experiment was undertaken on the Great Barrier Reef, within a no-fishing reserve where coral abundances and diversity had been sharply reduced by bleaching. In control areas, where fishes were abundant, algal abundance remained low, whereas coral cover almost doubled (to 20%) over a 3 year period, primarily because of recruitment of species that had been locally extirpated by bleaching. In contrast, exclusion of large herbivorous fishes caused a dramatic explosion of macroalgae, which suppressed the fecundity, recruitment, and survival of corals. Consequently, management of fish stocks is a key component in preventing phase shifts and managing reef resilience. Importantly, local stewardship of fishing effort is a tractable goal for conservation of reefs, and this local action can also provide some insurance against larger-scale disturbances such as mass bleaching, which are impractical to manage directly.

  6. Telecentric 3D profilometry based on phase-shifting fringe projection.

    Science.gov (United States)

    Li, Dong; Liu, Chunyang; Tian, Jindong

    2014-12-29

    Three dimensional shape measurement in the microscopic range becomes increasingly important with the development of micro manufacturing technology. Microscopic fringe projection techniques offer a fast, robust, and full-field measurement for field sizes from approximately 1 mm2 to several cm2. However, the depth of field is very small due to the imaging of non-telecentric microscope, which is often not sufficient to measure the complete depth of a 3D-object. And the calibration of phase-to-depth conversion is complicated which need a precision translation stage and a reference plane. In this paper, we propose a novel telecentric phase-shifting projected fringe profilometry for small and thick objects. Telecentric imaging extends the depth of field approximately to millimeter order, which is much larger than that of microscopy. To avoid the complicated phase-to-depth conversion in microscopic fringe projection, we develop a new system calibration method of camera and projector based on telecentric imaging model. Based on these, a 3D reconstruction of telecentric imaging is presented with stereovision aided by fringe phase maps. Experiments demonstrated the feasibility and high measurement accuracy of the proposed system for thick object.

  7. Linear q-nonuniform difference equations

    International Nuclear Information System (INIS)

    Bangerezako, Gaspard

    2010-01-01

    We introduce basic concepts of q-nonuniform differentiation and integration and study linear q-nonuniform difference equations and systems, as well as their application in q-nonuniform difference linear control systems. (author)

  8. Small-Signal Analysis of Single-Phase and Three-phase DC/AC and AC/DC PWM Converters with the Frequency-Shift Technique

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Aquila, A. Dell’; Liserre, Marco

    2004-01-01

    of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters......A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...

  9. Circadian phase, sleepiness, and light exposure assessment in night workers with and without shift work disorder.

    Science.gov (United States)

    Gumenyuk, Valentina; Roth, Thomas; Drake, Christopher L

    2012-08-01

    Most night workers are unable to adjust their circadian rhythms to the atypical hours of sleep and wake. Between 10% and 30% of shiftworkers report symptoms of excessive sleepiness and/or insomnia consistent with a diagnosis of shift work disorder (SWD). Difficulties in attaining appropriate shifts in circadian phase, in response to night work, may explain why some individuals develop SWD. In the present study, it was hypothesized that disturbances of sleep and wakefulness in shiftworkers are related to the degree of mismatch between their endogenous circadian rhythms and the night-work schedule of sleep during the day and wake activities at night. Five asymptomatic night workers (ANWs) (3 females; [mean ± SD] age: 39.2 ± 12.5 yrs; mean yrs on shift = 9.3) and five night workers meeting diagnostic criteria (International Classification of Sleep Disorders [ICSD]-2) for SWD (3 females; age: 35.6 ± 8.6 yrs; mean years on shift = 8.4) participated. All participants were admitted to the sleep center at 16:00 h, where they stayed in a dim light (individual melatonin profile. Objective sleepiness was assessed using the multiple sleep latency test (MSLT; 13 trials, 2-h intervals starting at 17:00 h). A Mann-Whitney U test was used for evaluation of differences between groups. The DLMO in ANW group was 04:42 ± 3.25 h, whereas in the SWD group it was 20:42 ± 2.21 h (z = 2.4; p groups, except the SWD group showed an earlier bedtime on off days from work relative to that in ANW group. The MSLT corresponding to night work time (01:00-09:00 h) was significantly shorter (3.6 ± .90 min: [M ± SEM]) in the SWD group compared with that in ANW group (6.8 ± .93 min). DLMO was significantly correlated with insomnia severity (r = -.68; p vs. 180 lux [M ± SD], respectively z = -1.7; p individuals with SWD maintain a circadian phase position similar to day workers, leading to a mismatch/conflict between their endogenous rhythms and their sleep-wake schedule.

  10. Optical path difference measurements with a two-step parallel phase shifting interferometer based on a modified Michelson configuration

    Science.gov (United States)

    Toto-Arellano, Noel Ivan; Serrano-Garcia, David I.; Rodriguez-Zurita, Gustavo

    2017-09-01

    We report an optical implementation of a parallel phase-shifting quasi-common path interferometer using two modified Michelson interferometers to generate two interferograms. By using a displaceable polarizer's array, placed on the image plane, we can obtain four phase-shifted interferograms in two captures. The system operates as a quasi-common path interferometer generating four beams, which are to interfere with alignment procedures on the mirrors of the Michelson configurations. The optical phase data are retrieved using the well-known four-step algorithms. To present the capabilities of the system, experimental results obtained from transparent structures are presented.

  11. Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift.

    Science.gov (United States)

    Ling, S D; Johnson, C R; Frusher, S D; Ridgway, K R

    2009-12-29

    A key consideration in assessing impacts of climate change is the possibility of synergistic effects with other human-induced stressors. In the ocean realm, climate change and overfishing pose two of the greatest challenges to the structure and functioning of marine ecosystems. In eastern Tasmania, temperate coastal waters are warming at approximately four times the global ocean warming average, representing the fastest rate of warming in the Southern Hemisphere. This has driven range extension of the ecologically important long-spined sea urchin (Centrostephanus rodgersii), which has now commenced catastrophic overgrazing of productive Tasmanian kelp beds leading to loss of biodiversity and important rocky reef ecosystem services. Coincident with the overgrazing is heavy fishing of reef-based predators including the spiny lobster Jasus edwardsii. By conducting experiments inside and outside Marine Protected Areas we show that fishing, by removing large predatory lobsters, has reduced the resilience of kelp beds against the climate-driven threat of the sea urchin and thus increased risk of catastrophic shift to widespread sea urchin barrens. This shows that interactions between multiple human-induced stressors can exacerbate nonlinear responses of ecosystems to climate change and limit the adaptive capacity of these systems. Management actions focused on reducing the risk of catastrophic phase shift in ecosystems are particularly urgent in the face of ongoing warming and unprecedented levels of predator removal from the world's oceans.

  12. Differential phase-shift keying and channel equalization in free space optical communication system

    Science.gov (United States)

    Zhang, Dai; Hao, Shiqi; Zhao, Qingsong; Wan, Xiongfeng; Xu, Chenlu

    2018-01-01

    We present the performance benefits of differential phase-shift keying (DPSK) modulation in eliminating influence from atmospheric turbulence, especially for coherent free space optical (FSO) communication with a high communication rate. Analytic expression of detected signal is derived, based on which, homodyne detection efficiency is calculated to indicate the performance of wavefront compensation. Considered laser pulses always suffer from atmospheric scattering effect by clouds, intersymbol interference (ISI) in high-speed FSO communication link is analyzed. Correspondingly, the channel equalization method of a binormalized modified constant modulus algorithm based on set-membership filtering (SM-BNMCMA) is proposed to solve the ISI problem. Finally, through the comparison with existing channel equalization methods, its performance benefits of both ISI elimination and convergence speed are verified. The research findings have theoretical significance in a high-speed FSO communication system.

  13. Quality investigation of surface mount technology using phase-shifting digital holography

    Science.gov (United States)

    Boonsri, Chantira; Buranasiri, Prathan

    2016-09-01

    Applying of a phase-shifting digital holography combined with compressive sensing to inspect the soldering quality of surface mount technology (SMT) which is a method for producing electronic circuits. In SMT, the components are mounted and connected with each other directly onto the surface of printed circuit boards (PCBs). By reconstructing the multidimensional images from a few samples of SMT, the results are solved by an optimization problem. In this paper, two problems have been concerned. The first one is to examine the devices and the soldering quality of connections between them, which are in micro-scaled. The second is to observe the effect of heat treatment of soldering material and devices on the surface mount board.

  14. Rapid yet accurate measurement of mass diffusion coefficients by phase shifting interferometer

    CERN Document Server

    Guo Zhi Xiong; Komiya, A

    1999-01-01

    The technique of using a phase-shifting interferometer is applied to the study of diffusion in transparent liquid mixtures. A quick method is proposed for determining the diffusion coefficient from the measurements of the location of fringes on a grey level picture. The measurement time is very short (within 100 s) and a very small transient diffusion field can be observed and recorded accurately with a rate of 30 frames per second. The measurement can be completed using less than 0.12 cc of solutions. The influence of gravity on the measurement of the diffusion coefficient is eliminated in the present method. Results on NaCl-water diffusion systems are presented and compared with the reference data. (author)

  15. Monitoring the thinning dynamics of soap films by phase shift interferometry. The case of perfluoropolyether surfactants.

    Science.gov (United States)

    Gambi, Cecilia M C; Vannoni, Maurizio; Sordini, Andrea; Molesini, Giuseppe

    2014-02-01

    An interferometric method to monitor the thinning process of vertical soap films from a water solution of surfactant materials is reported. Raw data maps of optical path difference introduced by the film are obtained by conventional phase shift interferometry. Off-line re-processing of such raw data taking into account the layered structure of soap films leads to an accurate measurement of the geometrical thickness. As an example of data acquisition and processing, the measuring chain is demonstrated on perfluoropolyether surfactants; the section profile of vertical films is monitored from drawing to black film state, and quantitative data on the dynamics of the thinning process are presented. The interferometric method proves effective to the task, and lends itself to further investigate the physical properties of soap films.

  16. Compact SOI optimized slot microring coupled phase-shifted Bragg grating resonator for sensing

    Science.gov (United States)

    Zhao, Chao Ying; Zhang, Lei; Zhang, Cheng Mei

    2018-05-01

    We propose a novel sensor structure composed of a slot microring and a phase-shifted sidewall Bragg gratings in a slot waveguide. We first present a theoretical analysis of transmission by using the transfer matrix. Then, the mode-field distributions of transmission spectrum obtained from 3D simulations based on FDTD method demonstrates that our sensor exhibit theoretical sensitivity of 297 . 13 nm / RIU, a minimum detection limit of 1 . 1 × 10-4 RIU, the maximum extinction ratio of 20 dB, the quality factor of 2 × 103 and a compact dimension-theoretical structure of 15 μm × 8 . 5 μm. Finally, the sensor's performance is simulated for NaCl solution.

  17. Application of ultrasound phase-shift analysis to authenticate wooden panel paintings.

    Science.gov (United States)

    Bravo, José M; Sánchez-Pérez, Juan V; Ferri, Marcelino; Redondo, Javier; Picó, Rubén

    2014-05-05

    Artworks are a valuable part of the World's cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated encoding system that enables authentication of the authorship of wooden panel paintings. The method has been evaluated in comparison with optical analysis and shows promising results. The proposed method provides an integrated fingerprint of the artwork, and could be used to enrich the cataloging and protection of artworks. Other advantages that make particularly attractive the proposed technique are its robustness and the use of low-cost sensors.

  18. Temperature measurement of an axisymmetric flame using phase shift holographic interferometry with fast Fourier transform

    Science.gov (United States)

    Tieng, S. M.; Lai, W. Z.

    Because of the importance of the temperature scalar measurements in combination diagonostics, application of phase shift holographic interferometry to temperature measurement of an axisymmetrically premixed flame was experimentally investigated. The test apparatus is an axisymmetric Bunsen burner. Propane of 99 percent purity is used as the gaseous fuel. A fast Fourier transform, a more efficient and accurate approach for Abel inversion, is used for reconstructed the axisymmetric temperature field from the interferometric data. The temperature distribution is compared with the thermocouple-measured values. The comparison shows that the proposed technique is satisfactory. The result errors are analyzed in detail. It is shown that this technique overcomes most of the earlier problems and limitations detrimental to the conventional holographic interferometry.

  19. Wave-mixing-induced transparency with zero phase shift in atomic vapors

    Science.gov (United States)

    Zhou, F.; Zhu, C. J.; Li, Y.

    2017-12-01

    We present a wave-mixing induced transparency that can lead to a hyper-Raman gain-clamping effect. This new type of transparency is originated from a dynamic gain cancellation effect in a multiphoton process where a highly efficient light field of new frequency is generated and amplified. We further show that this novel dynamic gain cancellation effect not only makes the medium transparent to a probe light field at appropriate frequency but also eliminates the probe field propagation phase shift. This gain-cancellation-based induced transparency holds for many potential applications on optical communication and may lead to effective suppression of parasitic Raman/hyper-Raman noise field generated in high intensity optical fiber transmissions.

  20. Comparison between phase shift derived and exactly calculated nucleon--nucleon interaction matrix elements

    International Nuclear Information System (INIS)

    Gregersen, A.W.

    1977-01-01

    A comparison is made between matrix elements calculated using the uncoupled channel Sussex approach to second order in DWBA and matrix elements calculated using a square well potential. The square well potential illustrated the problem of the determining parameter independence balanced with the concept of phase shift difference. The super-soft core potential was used to discuss the systematics of the Sussex approach as a function of angular momentum as well as the relation between Sussex generated and effective interaction matrix elements. In the uncoupled channels the original Sussex method of extracting effective interaction matrix elements was found to be satisfactory. In the coupled channels emphasis was placed upon the 3 S 1 -- 3 D 1 coupled channel matrix elements. Comparison is made between exactly calculated matrix elements, and matrix elements derived using an extended formulation of the coupled channel Sussex method. For simplicity the potential used is a nonseparable cut-off oscillator. The eigenphases of this potential can be made to approximate the realistic nucleon--nucleon phase shifts at low energies. By using the cut-off oscillator test potential, the original coupled channel Sussex method of determining parameter independence was shown to be incapable of accurately reproducing the exact cut-off oscillator matrix elements. The extended Sussex method was found to be accurate to within 10 percent. The extended method is based upon more general coupled channel DWBA and a noninfinite oscillator wave function solution to the cut-off oscillator auxiliary potential. A comparison is made in the coupled channels between matrix elements generated using the original Sussex method and the extended method. Tables of matrix elements generated using the original uncoupled channel Sussex method and the extended coupled channel Sussex method are presented for all necessary angular momentum channels

  1. Nonuniform sampling by quantiles.

    Science.gov (United States)

    Craft, D Levi; Sonstrom, Reilly E; Rovnyak, Virginia G; Rovnyak, David

    2018-02-13

    A flexible strategy for choosing samples nonuniformly from a Nyquist grid using the concept of statistical quantiles is presented for broad classes of NMR experimentation. Quantile-directed scheduling is intuitive and flexible for any weighting function, promotes reproducibility and seed independence, and is generalizable to multiple dimensions. In brief, weighting functions are divided into regions of equal probability, which define the samples to be acquired. Quantile scheduling therefore achieves close adherence to a probability distribution function, thereby minimizing gaps for any given degree of subsampling of the Nyquist grid. A characteristic of quantile scheduling is that one-dimensional, weighted NUS schedules are deterministic, however higher dimensional schedules are similar within a user-specified jittering parameter. To develop unweighted sampling, we investigated the minimum jitter needed to disrupt subharmonic tracts, and show that this criterion can be met in many cases by jittering within 25-50% of the subharmonic gap. For nD-NUS, three supplemental components to choosing samples by quantiles are proposed in this work: (i) forcing the corner samples to ensure sampling to specified maximum values in indirect evolution times, (ii) providing an option to triangular backfill sampling schedules to promote dense/uniform tracts at the beginning of signal evolution periods, and (iii) providing an option to force the edges of nD-NUS schedules to be identical to the 1D quantiles. Quantile-directed scheduling meets the diverse needs of current NUS experimentation, but can also be used for future NUS implementations such as off-grid NUS and more. A computer program implementing these principles (a.k.a. QSched) in 1D- and 2D-NUS is available under the general public license. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Nonuniform sampling by quantiles

    Science.gov (United States)

    Craft, D. Levi; Sonstrom, Reilly E.; Rovnyak, Virginia G.; Rovnyak, David

    2018-03-01

    A flexible strategy for choosing samples nonuniformly from a Nyquist grid using the concept of statistical quantiles is presented for broad classes of NMR experimentation. Quantile-directed scheduling is intuitive and flexible for any weighting function, promotes reproducibility and seed independence, and is generalizable to multiple dimensions. In brief, weighting functions are divided into regions of equal probability, which define the samples to be acquired. Quantile scheduling therefore achieves close adherence to a probability distribution function, thereby minimizing gaps for any given degree of subsampling of the Nyquist grid. A characteristic of quantile scheduling is that one-dimensional, weighted NUS schedules are deterministic, however higher dimensional schedules are similar within a user-specified jittering parameter. To develop unweighted sampling, we investigated the minimum jitter needed to disrupt subharmonic tracts, and show that this criterion can be met in many cases by jittering within 25-50% of the subharmonic gap. For nD-NUS, three supplemental components to choosing samples by quantiles are proposed in this work: (i) forcing the corner samples to ensure sampling to specified maximum values in indirect evolution times, (ii) providing an option to triangular backfill sampling schedules to promote dense/uniform tracts at the beginning of signal evolution periods, and (iii) providing an option to force the edges of nD-NUS schedules to be identical to the 1D quantiles. Quantile-directed scheduling meets the diverse needs of current NUS experimentation, but can also be used for future NUS implementations such as off-grid NUS and more. A computer program implementing these principles (a.k.a. QSched) in 1D- and 2D-NUS is available under the general public license.

  3. Simultaneous all-optical demultiplexing and regeneration based on self-phase and cross-phase modulation in a dispersion shifted fiber

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle

    2001-01-01

    Simultaneous demultiplexing and regeneration of 40-Gb/s optical time division multiplexed (OTDM) signal based on self-phase and cross-phase modulation in a dispersion shifted fiber is numerically and experimentally investigated. The optimal walkoff time between the control pulse and OTDM signal...

  4. Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier

    Directory of Open Access Journals (Sweden)

    Cheng-Tao Tsai

    2013-01-01

    Full Text Available This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR or a coupled current-doubler rectifier (CCDR is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications.

  5. Fast Scene Based Nonuniformity Correction with Minimal Temporal Latency

    Science.gov (United States)

    2006-09-01

    period of time. For example, the “Zenith camera” referenced in Elkins et al. can process 16 frames at a speed of 100 million frames per second (Mfps...derived to use whole shifts in - 42 - order to optimize for speed . The error introduced by uncertainty in the shifts is highly dependant on the...Sons, Inc. 1985. 3. Hayat, Majeed M; Ratliff, Bradley M; Tyo , J. Scott; Agi, Kamil. “Generalized Algebraic Scene-based Nonuniformity Correction

  6. Retrieval of Gap Fraction and Effective Plant Area Index from Phase-Shift Terrestrial Laser Scans

    Directory of Open Access Journals (Sweden)

    Pyare Pueschel

    2014-03-01

    Full Text Available The characterization of canopy structure is crucial for modeling eco-physiological processes. Two commonly used metrics for characterizing canopy structure are the gap fraction and the effective Plant Area Index (PAIe. Both have been successfully retrieved with terrestrial laser scanning. However, a systematic assessment of the influence of the laser scan properties on the retrieval of these metrics is still lacking. This study investigated the effects of resolution, measurement speed, and noise compression on the retrieval of gap fraction and PAIe from phase-shift FARO Photon 120 laser scans. We demonstrate that FARO’s noise compression yields gap fractions and PAIe that deviate significantly from those based on scans without noise compression and strongly overestimate Leaf Area Index (LAI estimates based on litter trap measurements. Scan resolution and measurement speed were also shown to impact gap fraction and PAIe, but this depended on leaf development phase, stand structure, and LAI calculation method. Nevertheless, PAIe estimates based on various scan parameter combinations without noise compression proved to be quite stable.

  7. Magnetic inductive phase shift: a new method to differentiate hemorrhagic stroke from ischemic stroke on rabbit.

    Science.gov (United States)

    Yan, Qingguang; Jin, Gui; Ma, Ke; Qin, Mingxin; Zhuang, Wei; Sun, Jian

    2017-05-30

    The major therapy for ischemic stroke is thrombolytic treatment, but severe consequences occur when this method is used to treat hemorrhagic stroke. Currently, computed tomography and magnetic resonance imaging are used to differentiate between two types of stroke, but these two methods are ineffective for pre-hospital care. We developed a new brain diagnostic device for rabbits based on electromagnetic induction to non-invasively differentiate two types of stroke. The device includes two coils and a phase difference measurement system that detects the magnetic inductive phase shift (MIPS) value to reflect the tissue's condition. The hemorrhage model was established through the injection of autologous blood into the internal capsule of a rabbit's brain. Ischemia was induced in the brain of a rabbit by bilateral carotid artery occlusion. Two types of animal models were measured with our device. The MIPS value gradually decreased with increasing injected blood and increased with ischemia time. The MIPS changes induced by the two types of strokes were exact opposites, and the absolute values of MIPS variation in the hemorrhagic and the ischemic groups were significantly larger than those of the normal control group (P stroke from hemorrhagic stroke on rabbit brain in a non-invasive, continuous, and bulk monitoring manner by using a simple and inexpensive apparatus.

  8. Surface modification of the MoSiON phase shift mask to reduce critical dimension variation

    Science.gov (United States)

    Choo, Hyeokseong; Seo, Dongwan; Lim, Sangwoo

    2013-10-01

    Phase shift masks (PSMs) were introduced to extend the limits of optical lithography. However, cleaning a MoSiON-based PSM pattern with an ammonium hydroxide/hydrogen peroxide mixture (APM), although efficient at cleaning the PSM pattern, etches the PSM layer, inducing changes in the phase angle and transmittance due to the introduction of variation of the critical dimension (CD). In this study, we investigated the effects of plasma treatment and furnace annealing on the etching of the MoSiON PSM in APM. In particular, we found that the etch behavior and surface chemical state after each treatment were correlated. We also compared variations in the CD between patterned PSM layers and blank masks. After O2 or N2 plasma treatment, the top surface of MoSiON had a thicker transition layer with an extreme increase in O, and a huge variation in CD was also observed after APM treatment. However, CD variation of the patterned MoSiON layer was minimal when the sample was first annealed in NH3 ambient gas and then subjected to APM treatment. This phenomenon may be related to an increase in the portion of the SiO2-like state at the top surface of the MoSiON PSM layer and its optimization without a change in the transition layer thickness.

  9. A new approach to estimating rainwater content by radar using propagation differential phase shift

    Science.gov (United States)

    Jameson, A. R.; Caylor, I. J.

    1994-01-01

    As microwaves propagate through rain, the rate of phase change with increasing distance is different depending upon whether the transmissions are polarized horizontally or vertically. This rate of change is the so-called specific propagation differential phase shift phi(sub DP). This paper demonstrates that at several frequencies and over a wide domain the ratio of phi(sub DP) to the rainwater content W is nearly linearly related to D(sub m), the mass-weighted mean drop size. An investigation of errors indicates that this new approach is likely to yield more accurate estimates of W than the other classical reflectivity factor Z, attenuation, or polarization techniques. The most accurate estimates of W are most likely at the highest frequency considered, 13.80 GHz. In lieu of such high-frequency measurements, these somewhat esoteric results are made more concrete through an analysis of 3-GHz radar measurements collected during the Convection and Precipitation Experiment in a tropical rainstorm in Florida. Among the principal advantages of using phi(sub DP) to measure rain are that an absolute calibration of the radar is no longer required and the estimates are decoupled from measurements of the radar reflectivity factor. Consequently, temporal and spatial structures of rain estimates do not simply mimic those of the reflectivity factor, as happens for classical estimation techniques using Z.

  10. Alternated phase-shift mask for 45nm node contact holes patterning

    Science.gov (United States)

    Cantu, Pietro; Capetti, Gianfranco; Catarisano, Chiara; D'Angelo, Fabrizio; Vaccaro, Alessandro

    2006-03-01

    Among other memory products FLASHes are becoming a technology driver in term of design rules aggressiveness for dense structures. Upcoming revisions of ITRS roadmap forecast 45nm technology node introduction for FLASHes one year ahead (2006) compared to DRAMs (2007). In this scenario the basic development of 45nm process requires patterned samples starting from the end of 2005. Waiting for hyper high NA ArF immersion tools availability, different RET solutions based on the existing lithography platforms have been evaluated with the aim to provide patterned samples for process modules development. Our paper is focused on 45nm node contact holes, certainly considered one of the most challenging layers in the technology assessment: various RET strategies will be briefly discussed and particular attention will be dedicated to alternating phase shift mask option. Strong PSM approach has been already proposed in the past as viable solution for 65nm node contact holes patterning using ArF tools; here we discuss problems related to its extension down to 45nm node (with dry equipments), in ultra low k I regime and close to the physical limit of 0.25 k I. The paper addresses main challenges related to the application of an alt PSM approach to a full chip FLASH design, suggesting possible solutions for assist features generation and phase assignment. Different strategies to compensate for the well known phase imbalance phenomena have been selected by using fully rigorous 3D optical simulations. Finally preliminary printing test will be shown. Lithography performances (Minimum resolution, Process window, contact profile) will be compared with conventional RET techniques.

  11. The Monte Carlo method as a tool for statistical characterisation of differential and additive phase shifting algorithms

    International Nuclear Information System (INIS)

    Miranda, M; Dorrio, B V; Blanco, J; Diz-Bugarin, J; Ribas, F

    2011-01-01

    Several metrological applications base their measurement principle in the phase sum or difference between two patterns, one original s(r,φ) and another modified t(r,φ+Δφ). Additive or differential phase shifting algorithms directly recover the sum 2φ+Δφ or the difference Δφ of phases without requiring prior calculation of the individual phases. These algorithms can be constructed, for example, from a suitable combination of known phase shifting algorithms. Little has been written on the design, analysis and error compensation of these new two-stage algorithms. Previously we have used computer simulation to study, in a linear approach or with a filter process in reciprocal space, the response of several families of them to the main error sources. In this work we present an error analysis that uses Monte Carlo simulation to achieve results in good agreement with those obtained with spatial and temporal methods.

  12. Stress analysis in the neighborhood around a hole in a tensile plate by photoelastic phase shifting method

    International Nuclear Information System (INIS)

    Lee, Chun Bae; Jung, Girl; Park, Tae Geun; Yang, Min Bok; Kim, Myung Soo; Baek, Tae Hyun

    2005-01-01

    This paper presents the experimental distributions of isochromatic fringes obtained in a quadrate plate which has a hole at its center. Isochromatic fringe are measured by the use of Tardy compensation method and phase shifting technique, and they are compared with those obtained from finite element method. Tardy compensation method is a conventional method and widely used but it is time-costing and inaccurate to obtain the movement of isoclinic fringe on a given point. Therefore, the 8-step phase shifting methodology is introduced and applied in this paper.

  13. A Modular Active Front-End Rectifier with Electronic Phase-Shifting for Harmonic Mitigation in Motor Drive Applications

    DEFF Research Database (Denmark)

    Zare, Firuz; Davari, Pooya; Blaabjerg, Frede

    2017-01-01

    In this paper, an electronic phase-shifting strategy has been optimized for a multi-parallel configuration of line-commutated rectifiers with a common dc-bus voltage used in motor drive application. This feature makes the performance of the system independent of the load profile and maximizes its...... harmonic reduction ability. In order to further reduce the generated low order harmonics, a dc-link current modulation scheme and its phase shift values of multi-drive systems have been optimized. Analysis, simulations and experiments have been carried out to verify the proposed method....

  14. Design of an optical temporal integrator based on a phase-shifted fiber Bragg grating in transmission.

    Science.gov (United States)

    Quoc Ngo, Nam

    2007-10-15

    We present a theoretical study of a new application of a simple pi-phase-shifted fiber Bragg grating (PSFBG) in transmission mode as a high-speed optical temporal integrator. The PSFBG consists of two concatenated identical uniform FBGs with a pi phase shift between them. When the reflectivities of the FBGs are extremely close to 100%, the transmissive PSFBG can perform the time integral of the complex envelope of an arbitrary input optical signal with high accuracy. As an example, the integrator is numerically shown to be able to convert an input Gaussian pulse into an optical step signal.

  15. Computational tool for phase-shift calculation in an interference pattern by fringe displacements based on a skeletonized image

    Science.gov (United States)

    Rivera-Ortega, Uriel; Pico-Gonzalez, Beatriz

    2016-01-01

    In this manuscript an algorithm based on a graphic user interface (GUI) designed in MATLAB for an automatic phase-shifting estimation between two digitalized interferograms is presented. The proposed algorithm finds the midpoint locus of the dark and bright interference fringes in two skeletonized fringe patterns and relates their displacements with the corresponding phase-shift. In order to demonstrate the usefulness of the proposed GUI, its application to simulated and experimental interference patterns will be shown. The viability of this GUI makes it a helpful and easy-to-use computational tool for educational or research purposes in optical phenomena for undergraduate or graduate studies in the field of physics.

  16. Phase-Space Reconstruction: a Path Towards the Next Generation of Nonlinear Differential Equation Based Models and Its Implications Towards Non-Uniform Sampling Theory

    Energy Technology Data Exchange (ETDEWEB)

    Charles R. Tolle; Mark Pengitore

    2009-08-01

    This paper explores the overlaps between the Control community’s work on System Identification (SysID) and the Physics, Mathematics, Chaos, and Complexity communities’ work on phase-space reconstruction via time-delay embedding. There are numerous overlaps between the goals of each community. Nevertheless, the Controls community can gain new insight as well as some new very powerful tools for SysID from the latest developments within the Physics, Mathematics, Chaos, and Complexity communities. These insights are gained via the work on phase-space reconstruction of non-linear dynamics. New methods for discovering non-linear differential based equations that evolved from embedding operations can shed new light on hybrid-systems theory, Nyquest-Shannon’s Theories, and network based control theory. This paper strives to guide the Controls community towards a closer inspection of the tools and additional insights being developed within the Physics, Mathematics, Chaos, and Complexity communities for discovery of system dynamics, the first step in control system development. The paper introduces the concepts of phase-space reconstruction via time-delay embedding (made famous byWhitney, Takens, and Sauer’s Thoreoms), intergrate-and-fire embedding, and non-linear differential equation discovery based on Perona’s method.

  17. Simultaneously frequency down-conversion, independent multichannel phase shifting and zero-IF receiving using a phase modulator in a sagnac loop and balanced detection

    Science.gov (United States)

    Zhu, Zihang; Zhao, Shanghong; Li, Xuan; Lin, Tao; Hu, Dapeng

    2018-03-01

    Photonic microwave frequency down-conversion with independent multichannel phase shifting and zero-intermediate frequency (IF) receiving is proposed and demonstrated by simulation. By combined use of a phase modulator (PM) in a sagnac loop and an optical bandpass filter (OBPF), orthogonal polarized carrier suppression single sideband (CS-SSB) signals are obtained. By adjusting the polarization controllers (PCs) to introduce the phase difference in the optical domain and using balanced detection to eliminate the direct current components, the phase of the generated IF signal can be arbitrarily tuned. Besides, the radio frequency (RF) vector signal can be also frequency down-converted to baseband directly by choosing two quadrature channels. In the simulation, high gain and continuously tunable phase shifts over the 360 degree range are verified. Furthermore, 2.5 Gbit/s RF vector signals centered at 10 GHz with different modulation formats are successfully demodulated.

  18. Phase shifts in binaural stimuli provide directional cues for sound localisation in the field cricket Gryllus bimaculatus.

    Science.gov (United States)

    Seagraves, Kelly M; Hedwig, Berthold

    2014-07-01

    The cricket's auditory system is a highly directional pressure difference receiver whose function is hypothesised to depend on phase relationships between the sound waves propagating through the auditory trachea that connects the left and right hearing organs. We tested this hypothesis by measuring the effect of experimentally constructed phase shifts in acoustic stimuli on phonotactic behavior of Gryllus bimaculatus, the oscillatory response patterns of the tympanic membrane, and the activity of the auditory afferents. The same artificial calling song was played simultaneously at the left and right sides of the cricket, but one sound pattern was shifted in phase by 90 deg (carrier frequencies between 3.6 and 5.4 kHz). All three levels of auditory processing are sensitive to experimentally induced acoustic phase shifts, and the response characteristics are dependent on the carrier frequency of the sound stimulus. At lower frequencies, crickets steered away from the sound leading in phase, while tympanic membrane vibrations and auditory afferent responses were smaller when the ipsilateral sound was leading. In contrast, opposite responses were observed at higher frequencies in all three levels of auditory processing. Minimal responses occurred near the carrier frequency of the cricket's calling song, suggesting a stability at this frequency. Our results indicate that crickets may use directional cues arising from phase shifts in acoustic signals for sound localisation, and that the response properties of pressure difference receivers may be analysed with phase-shifted sound stimuli to further our understanding of how insect auditory systems are adapted for directional processing. © 2014. Published by The Company of Biologists Ltd.

  19. Optical image encryption using chaos-based compressed sensing and phase-shifting interference in fractional wavelet domain

    Science.gov (United States)

    Liu, Qi; Wang, Ying; Wang, Jun; Wang, Qiong-Hua

    2018-02-01

    In this paper, a novel optical image encryption system combining compressed sensing with phase-shifting interference in fractional wavelet domain is proposed. To improve the encryption efficiency, the volume data of original image are decreased by compressed sensing. Then the compacted image is encoded through double random phase encoding in asymmetric fractional wavelet domain. In the encryption system, three pseudo-random sequences, generated by three-dimensional chaos map, are used as the measurement matrix of compressed sensing and two random-phase masks in the asymmetric fractional wavelet transform. It not only simplifies the keys to storage and transmission, but also enhances our cryptosystem nonlinearity to resist some common attacks. Further, holograms make our cryptosystem be immune to noises and occlusion attacks, which are obtained by two-step-only quadrature phase-shifting interference. And the compression and encryption can be achieved in the final result simultaneously. Numerical experiments have verified the security and validity of the proposed algorithm.

  20. Modulation analysis in spatial phase shifting electronic speckle pattern interferometry and application for automated data selection on biological specimens

    Science.gov (United States)

    Knoche, Sabine; Kemper, Björn; Wernicke, Günther; von Bally, Gert

    2007-02-01

    In electronic speckle pattern interferometry (ESPI), for a fast and objective analysis of measurement data which occur with a high repetition rate, an automated data processing is of particular advantage. For this reason, investigations were carried out to determine if the modulation of speckle interferograms can be applied as a quality parameter for the selection of suitable interferogram data for further evaluation e.g. phase unwrapping when spatial phase shifting (SPS) is performed. Six methods for determining the modulation of speckle interferograms are characterised and compared. The applicability of the speckle interferogram modulation as a parameter for mask generation in the unwrapping process of the phase difference is demonstrated by the evaluation of measurement data obtained from experiments with a spatial phase shifting endoscopic ESPI system on a technical surface and on a human gastrectomy specimen.

  1. Achieving High Absolute Accuracy for Group-Delay Measurements Using the Modulation Phase-Shift Technique

    Science.gov (United States)

    Dennis, T.; Williams, P. A.

    2005-11-01

    We have developed a modulation phase-shift (MPS) system for measuring relative group delay (RGD) in optical components with high absolute accuracy and simultaneously high temporal and wavelength resolution. Our 200-MHz system has a 3.2-pm wavelength resolution and has demonstrated a group-delay resolution of 0.072 ps for repeated measurements of an artifact based on a hydrogen-cyanide gas cell. The expanded uncertainty (2sigma) is +/-0.46 ps for a single spectral measurement (~ 3.4-pm steps) of a narrow 20-ps group-delay feature of the artifact. To our knowledge, this is the first time that the sources of measurement uncertainty for this technique have been described and quantified. A method for predicting the group delay of the gas-cell artifact from measured absorption spectra is described, and an uncertainty analysis for the prediction method is also presented. The implementation required to achieve results of the highest accuracy for both measurements and predictions is discussed.

  2. Interferometric interrogation of π-phase shifted fiber Bragg grating sensors

    Science.gov (United States)

    Srivastava, Deepa; Tiwari, Umesh; Das, Bhargab

    2018-03-01

    Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrates that high resolution weak dynamic strain measurement down to 4 pε /√{ Hz } is easily achievable. Preliminary experimental results are also presented as proof-of-concept of the proposed interrogation principle.

  3. A binary phase-shift keying receiver for the detection of attention to human speech.

    Science.gov (United States)

    Lopez-Gordo, M A; Pelayo, F

    2013-08-01

    Synthetic sounds, tone-beeps, vowels or syllables are typically used in the assessment of attention to auditory stimuli because they evoke a set of well-known event-related potentials, whose characteristics can be statistically contrasted. Such approach rules out the use of stimuli with non-predictable response, such as human speech. In this study we present a procedure based on the robust binary phase-shift keying (BPSK) receiver that permits the real-time detection of selective attention to human speeches in dichotic listening tasks. The goal was achieved by tagging the speeches with two barely-audible tags whose joined EEG response constitutes a reliable BPSK constellation, which can be detected by means of a BPSK receiver. The results confirmed the expected generation of the BPSK constellation by the human auditory system. Also, the bit-error rate and the information transmission rate achieved in the detection of attention fairly followed the expected curves and equations of the standard BPSK receiver. Actually, it was possible to detect attention as well as the estimation a priori of its accuracy based on the signal-to-noise ratio of the BPSK signals. This procedure, which permits the detection of the attention to human speeches, can be of interest for new potential applications, such as brain-computer interfaces, clinical assessment of the attention in real time or for entertainment.

  4. Phase shift PWM with double two-switch bridge for high power capacitor charging

    International Nuclear Information System (INIS)

    Karandikar, U.S.; Singh, Yashpal; Thakurta, A.C.

    2013-01-01

    Pulse power supply systems working at higher voltage and high repetition rate demands for higher power from capacitor chargers. Capacitor charging requirement become more challenging in such cases. In pulse power circuits, energy storage capacitor should be charged to its desired voltage before the next switching occurs. It is discharged within a small time, delivering large pulse power. A capacitor charger has to work with wide load variation repeatedly. Many schemes are used for this purpose. The proposed scheme aims at reducing stresses on switches by reducing peak current and their evils. A high voltage power supply is designed for capacitor charging. The proposed scheme is based on a Phase-Shifted PWM without using any extra component to achieve soft switching. Indirect constant average current capacitor charging is achieved with a simple control scheme. A double two-switch bridge is proposed to enhance reliability. Power supply has been developed to charge a capacitor of 50 μF to 2.5 kV at 25 Hz. (author)

  5. Real-time Noninvasive Monitoring of Intracranial Fluid Shifts During Dialysis Using Volumetric Integral Phase-Shift Spectroscopy (VIPS): A Proof-of-Concept Study.

    Science.gov (United States)

    Venkatasubba Rao, Chethan P; Bershad, Eric M; Calvillo, Eusebia; Maldonado, Nelson; Damani, Rahul; Mandayam, Sreedhar; Suarez, Jose I

    2018-02-01

    Cerebral edema, which is associated with increased intracranial fluid, is often a complication of many acute neurological conditions. There is currently no accepted method for real-time monitoring of intracranial fluid volume at the bedside. We evaluated a novel noninvasive technique called "Volumetric Integral Phase-shift Spectroscopy (VIPS)" for detecting intracranial fluid shifts during hemodialysis. Subjects receiving scheduled hemodialysis for end-stage renal disease and without a history of major neurological conditions were enrolled. VIPS monitoring was performed during hemodialysis. Serum osmolarity, electrolytes, and cognitive function with mini-mental state examination (MMSE) were assessed. Twenty-one monitoring sessions from 14 subjects (4 women), mean group age 50 (SD 12.6), were analyzed. The serum osmolarity decreased by a mean of 6.4 mOsm/L (SD 6.6) from pre- to post-dialysis and correlated with an increase in the VIPS edema index (E-Dex) of 9.7% (SD 12.9) (Pearson's correlation r = 0.46, p = 0.037). Of the individual determinants of serum osmolarity, changes in serum sodium level correlated best with the VIPS edema index (Pearson's correlation, r = 0.46, p = 0.034). MMSE scores did not change from pre- to post-dialysis. We detected an increase in the VIPS edema index during hemodialysis that correlated with decreased serum osmolarity, mainly reflected by changes in serum sodium suggesting shifts in intracranial fluids.

  6. Differentiation of osteoporotic and neoplastic vertebral fractures by chemical shift {l_brace}in-phase and out-of phase{r_brace} MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ragab, Yasser [Radiology Department, Faculty of Medicine, Cairo University (Egypt); Radiology Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail: yragab61@hotmail.com; Emad, Yasser [Rheumatology and Rehabilitation Department, Faculty of Medicine, Cairo University (Egypt); Rheumatology and Rehabilitation Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail: yasseremad68@yahoo.com; Gheita, Tamer [Rheumatology and Rehabilitation Department, Faculty of Medicine, Cairo University (Egypt)], E-mail: gheitamer@yahoo.com; Mansour, Maged [Oncology Department, Faculty of Medicine, Cairo University (Egypt); Oncology Department, Dr Erfan and Bagedo General Hospital (Saudi Arabia)], E-mail: magedmansour@yahoo.com; Abou-Zeid, A. [Public Health Department, Faculty of Medicine, Cairo University, Cairo (Egypt)], E-mail: alaabouzeid@yahoo.com; Ferrari, Serge [Division of Bone Diseases, Department of Rehabilitation and Geriatrics, and WHO, Collaborating Center for Osteoporosis Prevention, Geneva University Hospital (Switzerland)], E-mail: serge.ferrari@medecine.unige.ch; Rasker, Johannes J. [Rheumatologist University of Twente, Enschede (Netherlands)], E-mail: j.j.rasker@utwente.nl

    2009-10-15

    Objective: The objective of this study was to establish the cut-off value of the signal intensity drop on chemical shift magnetic resonance imaging (MRI) with appropriate sensitivity and specificity to differentiate osteoporotic from neoplastic wedging of the spine. Patients and methods: All patients with wedging of vertebral bodies were included consecutively between February 2006 and January 2007. A chemical shift MRI was performed and signal intensity after (in-phase and out-phase) images were obtained. A DXA was performed in all. Results: A total of 40 patients were included, 20 with osteoporotic wedging (group 1) and 20 neoplastic (group 2). They were 21 males and 19 females. Acute vertebral collapse was observed in 15 patients in group 1 and subacute collapse in another 5 patients, while in group 2, 11 patients showed acute collapse and 9 patients (45%) showed subacute vertebral collapse. On the chemical shift MRI a substantial reduction in signal intensity was found in all lesions in both groups. The proportional changes observed in signal intensity of bone marrow lesions on in-phase compared with out-of-phase images showed significant differences in both groups (P < 0.05). At a cut-off value of 35%, the observed sensitivity of out-of-phase images was 95%, specificity was 100%, positive predictive value was 100% and negative predictive value was 95.2%. Conclusion: A chemical shift MRI is useful in order to differentiate patients with vertebral collapse due to underlying osteoporosis or neoplastic process.

  7. Modified Two-core Phase-shifting Transformer Based on the Classical «Delta Connection» Scheme

    Directory of Open Access Journals (Sweden)

    Golub I.V.

    2016-04-01

    Full Text Available Nowadays, in joined power systems increases the role and significance of phase-shifting devices, which are used in the quality of FACTS-controllers (Flexible Alternative Current Transmission System, allowing solving various problems of modes management in a complex-closed inhomogeneous network. A modified version of the two-transformer circuit phase-adjusting device, built based on the classical single-transformer scheme «Delta Connection» has been studied in the paper. The proposed device’s topology differs from the classical of single-transformer one so that the control coil is supplied by a lower voltage than phase level, which in turn makes it possible to use it in high rated voltage networks. A mathematical model of the device, which describes the change of parameters of operation mode of phase-shifting transformer under the adjusting of the phase-shifting angle, has been provided. The achieved results can be used for comparative analysis when determining the technical and economic efficiency in the deal of further development of phase rotating devices of transformer type.

  8. A Double Phase-Shift Control Strategy for A Full-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Gong, Zheng

    2016-01-01

    In this paper, a double phase-shift control strategy is proposed for the full-bridge three-level (FBTL) DC/DC converter applied into DC distribution systems with the medium DC bus voltage. By utilizing the proposed control strategy, the voltage change rate dv/dt and voltage stress of the transfor...

  9. Design of all-optical high-order temporal integrators based on multiple-phase-shifted Bragg gratings.

    Science.gov (United States)

    Asghari, Mohammad H; Azaña, José

    2008-07-21

    In exact analogy with their electronic counterparts, photonic temporal integrators are fundamental building blocks for constructing all-optical circuits for ultrafast information processing and computing. In this work, we introduce a simple and general approach for realizing all-optical arbitrary-order temporal integrators. We demonstrate that the N(th) cumulative time integral of the complex field envelope of an input optical waveform can be obtained by simply propagating this waveform through a single uniform fiber/waveguide Bragg grating (BG) incorporating N pi-phase shifts along its axial profile. We derive here the design specifications of photonic integrators based on multiple-phase-shifted BGs. We show that the phase shifts in the BG structure can be arbitrarily located along the grating length provided that each uniform grating section (sections separated by the phase shifts) is sufficiently long so that its associated peak reflectivity reaches nearly 100%. The resulting designs are demonstrated by numerical simulations assuming all-fiber implementations. Our simulations show that the proposed approach can provide optical operation bandwidths in the tens-of-GHz regime using readily feasible photo-induced fiber BG structures.

  10. Using the phase shift to asymptotically characterize the dipolar mixed modes in post-main-sequence stars

    DEFF Research Database (Denmark)

    Jiang, C.; Christensen-Dalsgaard, J.; Cunha, M.

    2018-01-01

    Mixed modes have been extensively observed in post-main-sequence stars by the Kepler and CoRoT space missions. The mixture of the p and g modes can be measured by the dimensionless coefficient q, the so-called coupling strength factor. In this paper, we discuss the utility of the phase shifts θ f...

  11. High-order nonuniformly correlated beams

    Science.gov (United States)

    Wu, Dan; Wang, Fei; Cai, Yangjian

    2018-02-01

    We have introduced a class of partially coherent beams with spatially varying correlations named high-order nonuniformly correlated (HNUC) beams, as an extension of conventional nonuniformly correlated (NUC) beams. Such beams bring a new parameter (mode order) which is used to tailor the spatial coherence properties. The behavior of the spectral density of the HNUC beams on propagation has been investigated through numerical examples with the help of discrete model decomposition and fast Fourier transform (FFT) algorithm. Our results reveal that by selecting the mode order appropriately, the more sharpened intensity maxima can be achieved at a certain propagation distance compared to that of the NUC beams, and the lateral shift of the intensity maxima on propagation is closed related to the mode order. Furthermore, analytical expressions for the r.m.s width and the propagation factor of the HNUC beams on free-space propagation are derived by means of Wigner distribution function. The influence of initial beam parameters on the evolution of the r.m.s width and the propagation factor, and the relation between the r.m.s width and the occurring of the sharpened intensity maxima on propagation have been studied and discussed in detail.

  12. Phase shift from a coral to a corallimorph-dominated reef associated with a shipwreck on Palmyra atoll.

    Directory of Open Access Journals (Sweden)

    Thierry M Work

    Full Text Available Coral reefs can undergo relatively rapid changes in the dominant biota, a phenomenon referred to as phase shift. Various reasons have been proposed to explain this phenomenon including increased human disturbance, pollution, or changes in coral reef biota that serve a major ecological function such as depletion of grazers. However, pinpointing the actual factors potentially responsible can be problematic. Here we show a phase shift from coral to the corallimorpharian Rhodactis howesii associated with a long line vessel that wrecked in 1991 on an isolated atoll (Palmyra in the central Pacific Ocean. We documented high densities of R. howesii near the ship that progressively decreased with distance from the ship whereas R. howesii were rare to absent in other parts of the atoll. We also confirmed high densities of R. howesii around several buoys recently installed on the atoll in 2001. This is the first time that a phase shift on a coral reef has been unambiguously associated with man-made structures. This association was made, in part, because of the remoteness of Palmyra and its recent history of minimal human habitation or impact. Phase shifts can have long-term negative ramification for coral reefs, and eradication of organisms responsible for phase shifts in marine ecosystems can be difficult, particularly if such organisms cover a large area. The extensive R. howesii invasion and subsequent loss of coral reef habitat at Palmyra also highlights the importance of rapid removal of shipwrecks on corals reefs to mitigate the potential of reef overgrowth by invasives.

  13. Fast Method of Recovering Reference-Wave Intensity in Two-Step-Only Quadrature Phase-Shifting Holography

    Directory of Open Access Journals (Sweden)

    Wen-Jing Zhou

    2017-10-01

    Full Text Available We present a simple yet effective method, without the need for any additional recording of intensity maps or tremendous iterative computations, to recover reference-wave intensity resulting from the complex hologram acquired by quadrature phase-shifting holography. This is achieved by utilizing a certain area of interest in the complex hologram. We select a particular area in the complex hologram where there is negligible diffraction from the test sample to estimate the reference-wave intensity. The calculated intensity value allows us to extract exact phase distribution of the object in the context of two-step-only quadrature phase-shifting holography (TSO-PSH without the zeroth-order beam and the twin image noise on the reconstruction plane. Computer simulation and experimental results have been performed to verify the effectiveness and feasibility of our proposed method.

  14. Impact of Switching Harmonics on Capacitor Cells Balancing in Phase-Shifted PWM-Based Cascaded H-Bridge STATCOM

    DEFF Research Database (Denmark)

    Behrouzian, Ehsan; Bongiorno, Massimo; Teodorescu, Remus

    2017-01-01

    The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation. The case of high- and low-switching frequency for the converter cells is investi......The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation. The case of high- and low-switching frequency for the converter cells...... is investigated and the interaction between voltage and current harmonics is analyzed. It is shown that in both cases, this interaction results in an uneven power distribution among the cells in the same phase leg, leading to drifting of the dc-capacitor voltages and thereby the need for proper stabilization...

  15. Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

    Science.gov (United States)

    Gonzalez, Cesar A.; Valencia, Jose A.; Mora, Alfredo; Gonzalez, Fernando; Velasco, Beatriz; Porras, Martin A.; Salgado, Javier; Polo, Salvador M.; Hevia-Montiel, Nidiyare; Cordero, Sergio; Rubinsky, Boris

    2013-01-01

    Motivated by the need of poor and rural Mexico, where the population has limited access to advanced medical technology and services, we have developed a new paradigm for medical diagnostic based on the technology of “Volumetric Electromagnetic Phase Shift Spectroscopy” (VEPS), as an inexpensive partial substitute to medical imaging. VEPS, can detect changes in tissue properties inside the body through non-contact, multi-frequency electromagnetic measurements from the exterior of the body, and thereby provide rapid and inexpensive diagnostics in a way that is amenable for use in economically disadvantaged parts of the world. We describe the technology and report results from a limited pilot study with 46 healthy volunteers and eight patients with CT radiology confirmed brain edema and brain hematoma. Data analysis with a non-parametric statistical Mann-Whitney U test, shows that in the frequency range of from 26 MHz to 39 MHz, VEPS can distinguish non-invasively and without contact, with a statistical significance of p<0.05, between healthy subjects and those with a medical conditions in the brain. In the frequency range of between 153 MHz to 166 MHz it can distinguish with a statistical significance of p<0.05 between subjects with brain edema and those with a hematoma in the brain. A classifier build from measurements in these two frequency ranges can provide instantaneous diagnostic of the medical condition of the brain of a patient, from a single set of measurements. While this is a small-scale pilot study, it illustrates the potential of VEPS to change the paradigm of medical diagnostic of brain injury through a VEPS classifier-based technology. Obviously substantially larger-scale studies are needed to verify and expand on the findings in this small pilot study. PMID:23691001

  16. 3D velocity measurement by a single camera using Doppler phase-shifting holography

    International Nuclear Information System (INIS)

    Ninomiya, Nao; Kubo, Yamato; Barada, Daisuke; Kiire, Tomohiro

    2016-01-01

    In order to understand the details of the flow field in micro- and nano-fluidic devices, it is necessary to measure the 3D velocities under a microscopy. Thus, there is a strong need for the development of a new measuring technique for 3D velocity by a single camera. One solution is the use of holography, but it is well known that the accuracy in the depth direction is very poor for the commonly used in-line holography. At present, the Doppler phase-shifting holography is used for the 3D measurement of an object. This method extracts the signal of a fixed frequency caused by the Doppler beat between the object light and the reference light. It can measure the 3D shape precisely. Here, the frequency of the Doppler beat is determined by the velocity difference between the object light and the reference light. This implies that the velocity of an object can be calculated by the Doppler frequency. In this study, a Japanese 5 yen coin was traversed at a constant speed and its holography has been observed by a high-speed camera. By extracting only the first order diffraction signal at the Doppler frequency, a precise measurement of the shape and the position of a 5 yen coin has been achieved. At the same time, the longitudinal velocity of a 5 yen coin can be measured by the Doppler frequency. Furthermore, the lateral velocities are obtained by particle image velocimetry (PIV) method. A 5 yen coin has been traversed at different angles and its shapes and the 3D velocities have been measured accurately. This method can be applied to the particle flows in the micro- or nano-devices, and the 3D velocities will be measured under microscopes. (paper)

  17. Phase Balancing by Means of Electric Vehicles Single-Phase Connection Shifting in a Low Voltage Danish Grid

    DEFF Research Database (Denmark)

    Lico, Pasqualino; Marinelli, Mattia; Knezovic, Katarina

    2015-01-01

    In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise...... stations are equipped with single-phase converters. According to the designed control strategy, the charging spot can select the phase to be used for the charge. The selection is done according to a phase voltage measurement....

  18. Studies in A-scan echoencephalography: evaluation of a proposed two phase shift

    Directory of Open Access Journals (Sweden)

    Helio Lemmi

    1969-09-01

    Full Text Available A series of 440 patients studied by echoencephalography is reported. Rather than dividing the patients in the classic two groups of less than 3 mm and more than 3 mm deviation of the midline, the patients in this study were divided into three groups, correlating the degree of midline shift to the presence of intracranial pathology. Group I, showing 0 to 2.5 mm shift proves to be normal with a "miss" rate of only 10%. Group II, showing 2.5 to 3.5 mm shift is regarded as a borderline group with an incidence of significant intracranial pathology of 46%, clearly indicating the need for further evaluation. Group III, demonstrating greater than 3.5 mm shift from the midline, is designated with confidence as abnormal, with a yield of significant intracranial pathology of 100% in this study.

  19. Testing of cavity attenuation phase shift technology for siting near-road NO2 monitors.

    Science.gov (United States)

    2015-07-01

    Recent research has identified the public health importance of air pollution exposures : near busy roadways. As a result, EPA significantly revised its NO2 air quality standard in 2010. : The current regulatory focus has shifted from assessment of lo...

  20. Contact-less magneto-elastic torsional sensor based on phase-shift measurements

    International Nuclear Information System (INIS)

    Buchenau, D; Schmidt, G; Eckert, S

    2014-01-01

    We report on the development of a contact-less measurement technique for torsional shear stress τ in ferromagnetic axles or hollow shafts, based on the magneto-elastic effect. In general, two different measuring principles for ferromagnetic materials can be realized, based on: the evaluation of the change of magnetic polarization influenced by shear stress ΔJ(τ) or the change of the magnetic susceptibility Δχ A (τ). The comprehension of the magnetic polarization or the magnetic susceptibility in a sensor concept requires an external magnetic field. Alternating magnetic fields were used as shear stress can disturb not only the amplitude but also the phase distribution of the applied magnetic field. As a result of a torsional moment acting on an axle or hollow shaft, an angle of twist η appears, which is constant over the length of the twisted object. This angle of twist can be understood as a shift of infinitesimal thin cross-sections in which the whole length of the axle is separated. Besides the macroscopic deformation effect, shear forces also affect the Weiss-domains in the micro-scale of the ferromagnetic material. The effects in the micro-scale are the base of the magneto-elastic effect. The combination of the deformation effect in the macro-scale and the deformation of the Weiss-domains in the micro-scale leads to a sophisticated measurement principle for torsional stress in axles or hollow shafts. Magneto-sensitive detectors along or around the measurement object open up the possibility for a contact-less detection of torsional stress in ferromagnetic materials. Besides a strong measuring signal, free from electromagnetic interference, the introduced contact-less measurement principle offers different advantages, like independence from compression strength, nominal tensile stress, impact load, ferromagnetic hysteresis effects and independence of the temperature-dependent electrical conductivity of the axle or hollow shaft. The characteristics of such

  1. New generalized phase shift approach to solve the Helmholtz acoustic wave equation

    Science.gov (United States)

    Abeykoon, Sameera K. (Nee Rajapakshe)

    2008-10-01

    We have developed and given some proof of concept applications of a new method of solving the Helmholtz wave equation in order to facilitate the exploration of oil and gas. The approach is based on a new way to generalize the "one-way" wave equation, and to impose correct boundary conditions. The full two-way nature of the Helmholtz equation is considered, but converted into a pseudo "one-way" form with a generalized phase shift structure for propagation in the depth z. Two coupled first order partial differential equations in the depth variable z are obtained from the Helmholtz wave equation. Our approach makes use of very simple, standard ideas from differential equations and early ideas on the non-iterative solution of the Lippmann-Schwinger equation in quantum scattering. In addition, a judicious choice of operator splitting is introduced to ensure that only explicit solution techniques are required. This avoids the need for numerical matrix inversions. The initial conditions are more challenging due to the need to ensure that the solution satisfies proper boundary conditions associated with the waves traveling in two directions. This difficulty is resolved by solving the Lippmann-Schwinger integral equation in an explicit, non-iterative fashion. It is solved by essentially "factoring out" the physical boundary conditions, thereby converting the inhomogeneous Lippmann-Schwinger integral equation of the second kind into a Volterra integral equation of the second kind. Due to the special structure of the kernel, which is a consequence of the causal nature of the Green's function in the Lippmann-Schwinger equation, this turns out to be extremely efficient. The coupled first order differential equations will be solved using the "modified Cayley method" developed in Kouri's group some years ago. The Feshbach projection operator technique is used for constructing a solution that is stable with respect to "evanescent" or "non-propagating" waves. This method is

  2. The renormalised π NN coupling constant and the P-wave phase shifts in the cloudy bag model

    International Nuclear Information System (INIS)

    Pearce, B.C.; Afnan, I.R.

    1986-02-01

    Most applications of the cloudy bag model to π N scattering involve unitarising the bare diagrams arising from the Lagrangian by iterating in a Lippmann-Schwinger equation. However analyses of the renormalisation of the coupling constant proceed by iterating the Lagrangian to a given order in the bare coupling constant. These two different approaches means there is an inconsistency between the calculation of phase shifts and the calculation of renormalisation. A remedy to this problem is presented that has the added advantage of improving the fit to the phase shifts in the P 11 channel. This is achieved by using physical values of the coupling constant in the crossed diagram which reduces the repulsion rather than adds attraction. This approach can be justified by examining equations for the π π N system that incorporate three-body unitarity

  3. High-quality phase-shifted Bragg grating sensor inscribed with only one laser pulse in a polymer optical fiber

    DEFF Research Database (Denmark)

    Marques, C. A. F.; Pospori, A.; Pereira, L.

    2017-01-01

    We present the first phase-shifted polymer optical fiber Bragg grating sensor inscribed with only one KrF laser pulse. The phase shift defect was created directly during the grating inscription process by placing a very narrow blocking aperture, in the center of the UV beam. One laser pulse...... with a duration of 15 ns and energy 6.3 mJ is adequate to introduce a refractive index change of 0.69×10−4 in the fiber core. The high-quality produced Bragg grating structure rejects 16.3 dB transmitted power, thus providing 97.6% reflectivity, which is well suited for photonic applications. The transmission...

  4. Broadband tunable bandpass filters using phase shifted vertical side wall grating in a submicrometer silicon-on-insulator waveguide.

    Science.gov (United States)

    Prabhathan, P; Murukeshan, V M; Jing, Zhang; Ramana, Pamidighantam V

    2009-10-10

    We propose the silicon-on-insulator (SOI) based, phase shifted vertical side wall grating as a resonant transmission filter suitable for dense wavelength division multiplexing (DWDM) communication channels with 100 GHz channel spacing. The gratings are designed and numerically simulated to obtain a minimum loss in the resonant cavity by adjusting the grating parameters so that a high transmittivity can be achieved for the resonant transmission. The resonant grating, which is designed to operate in the DWDM International Telecommunication Union (ITU) grid C band of optical communication, has a high free spectral range of 51.7 nm and a narrow band resonant transmission. The wavelength selectivity of the filter is improved through a coupled cavity configuration by applying two phase shifts to the gratings. The observed channel band width and channel isolation of the resonant transmission filter are good and in agreement with the ITU specifications.

  5. Deep-turbulence wavefront sensing using digital holography in the on-axis phase shifting recording geometry

    Science.gov (United States)

    Thornton, Douglas E.; Spencer, Mark F.; Perram, Glen P.

    2017-09-01

    The effects of deep turbulence in long-range imaging applications presents unique challenges to properly measure and correct for aberrations incurred along the atmospheric path. In practice, digital holography can detect the path-integrated wavefront distortions caused by deep turbulence, and di erent recording geometries offer different benefits depending on the application of interest. Previous studies have evaluated the performance of the off-axis image and pupil plane recording geometries for deep-turbulence sensing. This study models digital holography in the on-axis phase shifting recording geometry using wave optics simulations. In particular, the analysis models spherical-wave propagation through varying deep-turbulence conditions to estimate the complex optical field, and performance is evaluated by calculating the field-estimated Strehl ratio and RMS wavefront error. Altogether, the results show that digital holography in the on-axis phase shifting recording geometry is an effective wavefront-sensing method in the presence of deep turbulence.

  6. Using the phase shift to asymptotically characterize the dipolar mixed modes in post-main-sequence stars

    Science.gov (United States)

    Jiang, C.; Christensen-Dalsgaard, J.; Cunha, M.

    2018-03-01

    Mixed modes have been extensively observed in post-main-sequence stars by the Kepler and CoRoT space missions. The mixture of the p and g modes can be measured by the dimensionless coefficient q, the so-called coupling strength factor. In this paper, we discuss the utility of the phase shifts θ from the eigenvalue condition for mixed modes as a tool to characterize dipolar mixed modes from the theoretical as well as the practical point of view. Unlike the coupling strength, whose variation in a given star is very small over the relevant frequency range, the phase shifts vary significantly for different modes. The analysis in terms of θ can also provide a better understanding of the pressure and gravity radial order for a given mixed mode. Observed frequencies of the Kepler red-giant star KIC 3744043 are used to test the method. The results are very promising.

  7. Design of high-order all-optical temporal differentiators based on multiple-phase-shifted fiber Bragg gratings.

    Science.gov (United States)

    Kulishov, Mykola; Azaña, José

    2007-05-14

    A simple and general approach for designing practical all-optical (all-fiber) arbitrary-order time differentiators is introduced here for the first time. Specifically, we demonstrate that the Nth time derivative of an input optical waveform can be obtained by reflection of this waveform in a single uniform fiber Bragg grating (FBG) incorporating N &pi-phase shifts properly located along its grating profile. The general design procedure of an arbitrary-order optical time differentiator based on a multiple-phase-shifted FBG is described and numerically demonstrated for up to fourth-order time differentiation. Our simulations show that the proposed approach can provide optical operation bandwidths in the tens-of-GHz regime using readily feasible FBG structures.

  8. Experimental study of entanglement evolution in the presence of bit-flip and phase-shift noises

    Science.gov (United States)

    Liu, Xia; Cao, Lian-Zhen; Zhao, Jia-Qiang; Yang, Yang; Lu, Huai-Xin

    2017-10-01

    Because of its important role both in fundamental theory and applications in quantum information, evolution of entanglement in a quantum system under decoherence has attracted wide attention in recent years. In this paper, we experimentally generate a high-fidelity maximum entangled two-qubit state and present an experimental study of the decoherence properties of entangled pair of qubits at collective (non-collective) bit-flip and phase-shift noises. The results shown that entanglement decreasing depends on the type of the noises (collective or non-collective and bit-flip or phase-shift) and the number of qubits which are subject to the noise. When two qubits are depolarized passing through non-collective noisy channel, the decay rate is larger than that depicted for the collective noise. When two qubits passing through depolarized noisy channel, the decay rate is larger than that depicted for one qubit.

  9. Short-coherence in-line phase-shifting infrared digital holographic microscopy for measurement of internal structure in silicon

    Science.gov (United States)

    Xi, Teli; Dou, Jiazhen; Di, Jianglei; Li, Ying; Zhang, Jiwei; Ma, Chaojie; Zhao, Jianlin

    2017-06-01

    Short-coherence in-line phase-shifting digital holographic microscopy based on Michelson interferometer is proposed to measure internal structure in silicon. In the configuration, a short-coherence infrared laser is used as the light source in order to avoid the interference formed by the reference wave and the reflected wave from the front surface of specimen. At the same time, in-line phase-shifting configuration is introduced to overcome the problem of poor resolution and large pixel size of the infrared camera and improve the space bandwidth product of the system. A specimen with staircase structure is measured by using the proposed configuration and the 3D shape distribution are given to verify the effectiveness and accuracy of the method.

  10. Validity of the relativistic phase shift model for the extrinsic spin Hall effect in dilute metal alloys.

    Science.gov (United States)

    Johansson, A; Herschbach, C; Fedorov, D V; Gradhand, M; Mertig, I

    2014-07-09

    Recently, a generalized relativistic phase shift model was proposed (Fedorovet al 2013 Phys. Rev. B 88 085116) for the description of the skew-scattering contribution to the spin Hall effect caused by impurities. Here, we inspect this model by means of a systematic comparison with the results of first-principles calculations performed for several metallic host systems with different substitutional impurities. It is found that for its proper application, the differences between impurity and host phase shifts should be used as input parameters. Generally, the model provides good qualitative agreement with ab initio results for hosts with a free-electron-like Fermi surface and a relatively weak spin-orbit coupling, but fails otherwise.

  11. Rayleigh noise mitigation in DWDM LR-PONs using carrier suppressed subcarrier-amplitude modulated phase shift keying.

    Science.gov (United States)

    Chow, C W; Talli, G; Ellis, A D; Townsend, P D

    2008-02-04

    We demonstrate a novel Rayleigh interferometric noise mitigation scheme for applications in carrier-distributed dense wavelength division multiplexed (DWDM) passive optical networks at 10 Gbit/s using carrier suppressed subcarrier-amplitude modulated phase shift keying modulation. The required optical signal to Rayleigh noise ratio is reduced by 12 dB, while achieving excellent tolerance to dispersion, subcarrier frequency and drive amplitude variations.

  12. Differential-phase-shift quantum key distribution experiment using fast physical random bit generator with chaotic semiconductor lasers.

    Science.gov (United States)

    Honjo, Toshimori; Uchida, Atsushi; Amano, Kazuya; Hirano, Kunihito; Someya, Hiroyuki; Okumura, Haruka; Yoshimura, Kazuyuki; Davis, Peter; Tokura, Yasuhiro

    2009-05-25

    A high speed physical random bit generator is applied for the first time to a gigahertz clocked quantum key distribution system. Random phase-modulation in a differential-phase-shift quantum key distribution (DPS-QKD) system is performed using a 1-Gbps random bit signal which is generated by a physical random bit generator with chaotic semiconductor lasers. Stable operation is demonstrated for over one hour, and sifted keys are successfully generated at a rate of 9.0 kbps with a quantum bit error rate of 3.2% after 25-km fiber transmission.

  13. Electrical system using phase-shifted carrier signals and related operating methods

    Science.gov (United States)

    Welchko, Brian A; Campbell, Jeremy B

    2012-09-18

    An automotive drive system and methods for making the same are provided. The system includes a three-phase motor and an inverter module. The three-phase motor includes a first set of windings each having a first magnetic polarity; and a second set of windings each having a second magnetic polarity that is opposite the first magnetic polarity. The first set of windings being electrically isolated from the second set of windings. The inverter module includes a first set of phase legs and a second set of phase legs. Each one of the first set of phase legs is coupled to a corresponding phase of the first set of windings, and each one of the second set of phase legs is coupled to a corresponding phase of the second set of windings.

  14. Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves

    Science.gov (United States)

    Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, J. Bernard; Wygant, J. R.; Kletzing, C. A.

    2017-02-01

    We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ˜450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (˜50 to 150 keV) across the estimated resonant energy (˜104 keV) is ˜360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift-resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave-particle interaction in the magnetosphere.

  15. Performance comparison of 0/π- and ± π/2-phase-shifted superstructured Fiber Bragg grating en/decoder.

    Science.gov (United States)

    Dai, Bo; Gao, Zhensen; Wang, Xu; Kataoka, Nobuyuki; Wada, Naoya

    2011-06-20

    We compare the performances of the 0/π-phase-shifted SSFBG (0/π-SSFBG) and the ± π/2-phase-shifted SSFBG (± π/2-SSFBG) en/decoders in the three aspects: the security, coding and system performances. In terms of the security performance, we evaluate the security performance by the investigation on the encoded waveform of both encoders. We also propose and demonstrate the code extraction technique for the ± π/2-SSFBG encoder when input pulse has large pulse width. Then, we analyze the coding performance of these two kinds of en/decoders by the calculation of autocorrelation and cross-correlation with sets of 31-chip, 63-chip and 127-chip Gold codes. Furthermore, we propose and demonstrate the hybrid use of both en/decoders. To demonstrate the performance of both en/decoders and the hybrid use in the different systems, we employ four 31-chip 640 Gchip/s 0/π-SSFBG and ± π/2-SSFBG en/decoders in the 4-user 10 Gbps/user on-off keying and differential phase-shift keying OCDMA systems.

  16. Velocity encoding with the slice select refocusing gradient for faster imaging and reduced chemical shift-induced phase errors.

    Science.gov (United States)

    Middione, Matthew J; Thompson, Richard B; Ennis, Daniel B

    2014-06-01

    To investigate a novel phase-contrast MRI velocity-encoding technique for faster imaging and reduced chemical shift-induced phase errors. Velocity encoding with the slice select refocusing gradient achieves the target gradient moment by time shifting the refocusing gradient, which enables the use of the minimum in-phase echo time (TE) for faster imaging and reduced chemical shift-induced phase errors. Net forward flow was compared in 10 healthy subjects (N = 10) within the ascending aorta (aAo), main pulmonary artery (PA), and right/left pulmonary arteries (RPA/LPA) using conventional flow compensated and flow encoded (401 Hz/px and TE = 3.08 ms) and slice select refocused gradient velocity encoding (814 Hz/px and TE = 2.46 ms) at 3 T. Improved net forward flow agreement was measured across all vessels for slice select refocused gradient compared to flow compensated and flow encoded: aAo vs. PA (1.7% ± 1.9% vs. 5.8% ± 2.8%, P = 0.002), aAo vs. RPA + LPA (2.1% ± 1.7% vs. 6.0% ± 4.3%, P = 0.03), and PA vs. RPA + LPA (2.9% ± 2.1% vs. 6.1% ± 6.3%, P = 0.04), while increasing temporal resolution (35%) and signal-to-noise ratio (33%). Slice select refocused gradient phase-contrast MRI with a high receiver bandwidth and minimum in-phase TE provides more accurate and less variable flow measurements through the reduction of chemical shift-induced phase errors and a reduced TE/repetition time, which can be used to increase the temporal/spatial resolution and/or reduce breath hold durations. Copyright © 2013 Wiley Periodicals, Inc.

  17. The effect of the condensed-phase environment on the vibrational frequency shift of a hydrogen molecule inside clathrate hydrates.

    Science.gov (United States)

    Powers, Anna; Scribano, Yohann; Lauvergnat, David; Mebe, Elsy; Benoit, David M; Bačić, Zlatko

    2018-04-14

    We report a theoretical study of the frequency shift (redshift) of the stretching fundamental transition of an H 2 molecule confined inside the small dodecahedral cage of the structure II clathrate hydrate and its dependence on the condensed-phase environment. In order to determine how much the hydrate water molecules beyond the confining small cage contribute to the vibrational frequency shift, quantum five-dimensional (5D) calculations of the coupled translation-rotation eigenstates are performed for H 2 in the v=0 and v=1 vibrational states inside spherical clathrate hydrate domains of increasing radius and a growing number of water molecules, ranging from 20 for the isolated small cage to over 1900. In these calculations, both H 2 and the water domains are treated as rigid. The 5D intermolecular potential energy surface (PES) of H 2 inside a hydrate domain is assumed to be pairwise additive. The H 2 -H 2 O pair interaction, represented by the 5D (rigid monomer) PES that depends on the vibrational state of H 2 , v=0 or v=1, is derived from the high-quality ab initio full-dimensional (9D) PES of the H 2 -H 2 O complex [P. Valiron et al., J. Chem. Phys. 129, 134306 (2008)]. The H 2 vibrational frequency shift calculated for the largest clathrate domain considered, which mimics the condensed-phase environment, is about 10% larger in magnitude than that obtained by taking into account only the small cage. The calculated splittings of the translational fundamental of H 2 change very little with the domain size, unlike the H 2 j = 1 rotational splittings that decrease significantly as the domain size increases. The changes in both the vibrational frequency shift and the j = 1 rotational splitting due to the condensed-phase effects arise predominantly from the H 2 O molecules in the first three complete hydration shells around H 2 .

  18. Pion-pion phase shifts from two loop chiral perturbation theory

    International Nuclear Information System (INIS)

    Borges, J. Sa; Barbosa, J. Soares; Tonasse, M.

    1999-01-01

    We present a two parameters fit of low energy P-wave shifts, using the recent published results of pion-pion scattering amplitudes from chiral perturbation theory, including two loops contributions. We show that, once given the P-wave, the isospin zero S-waves is in good agreement with experimental data. (author)

  19. Cryptosystem based on two-step phase-shifting interferometry and the RSA public-key encryption algorithm

    Science.gov (United States)

    Meng, X. F.; Peng, X.; Cai, L. Z.; Li, A. M.; Gao, Z.; Wang, Y. R.

    2009-08-01

    A hybrid cryptosystem is proposed, in which one image is encrypted to two interferograms with the aid of double random-phase encoding (DRPE) and two-step phase-shifting interferometry (2-PSI), then three pairs of public-private keys are utilized to encode and decode the session keys (geometrical parameters, the second random-phase mask) and interferograms. In the stage of decryption, the ciphered image can be decrypted by wavefront reconstruction, inverse Fresnel diffraction, and real amplitude normalization. This approach can successfully solve the problem of key management and dispatch, resulting in increased security strength. The feasibility of the proposed cryptosystem and its robustness against some types of attack are verified and analyzed by computer simulations.

  20. The role of competition in the phase shift to dominance of the zoanthid Palythoa cf. variabilis on coral reefs.

    Science.gov (United States)

    Cruz, Igor Cristino Silva; Meira, Verena Henschen; de Kikuchi, Ruy Kenji Papa; Creed, Joel Christopher

    2016-04-01

    Phase shift phenomena are becoming increasingly common. However, they are also opportunities to better understand how communities are structured. In Southwest Atlantic coral reefs, a shift to the zoanthid Palythoa cf. variabilis dominance has been described. To test if competition drove this process, we carried out a manipulative experiment with three coral species. To estimate the natural frequency of encounters we assess the relationship between the proportion of encounters and this zoanthids coverage. The contact causes necrosis in 78% of coral colonies (6.47 ± SD 7.92 cm(2)) in 118 days. We found a logarithmic relationship between the proportion of these encounters and the cover of P. cf. variabilis, where 5.5% coverage of this zoanthid is enough to put 50% of coral colonies in contact, increasing their partial mortality. We demonstrate that zoanthid coverage increase followed by coral mortality increase will reduce coral cover and that competition drives the phase shift process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. High speed all-optical PRBS generation using binary phase shift keyed signal based on QD-SOA

    Science.gov (United States)

    Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2014-09-01

    A scheme to generate return-to-zero on-off keying (RZ-OOK) high speed all-optical pseudo random bit sequence (PRBS) using binary phase shift keyed (BPSK) signal based on quantum-dot semiconductor optical amplifiers (QD-SOA) has been designed and studied. The PRBS is generated by a linear feedback shift register (LFSR) composed of all-optical logic XOR and AND gates. The XOR gate is composed of a pair of QD SOA Mach-Zehnder interferometers, which can generate BSPK signal to realize all-optical logic XOR gate. Results show that this scheme can mitigate the patterning effects and increase the operation speed to ~250Gb/s.

  2. Tunable sensitivity phase detection of transmitted-type dual-channel guided-mode resonance sensor based on phase-shift interferometry.

    Science.gov (United States)

    Kuo, Wen-Kai; Syu, Siang-He; Lin, Peng-Zhi; Yu, Hsin Her

    2016-02-01

    This paper reports on a transmitted-type dual-channel guided-mode resonance (GMR) sensor system that uses phase-shifting interferometry (PSI) to achieve tunable phase detection sensitivity. Five interference images are captured for the PSI phase calculation within ∼15  s by using a liquid crystal retarder and a USB web camera. The GMR sensor structure is formed by a nanoimprinting process, and the dual-channel sensor device structure for molding is fabricated using a 3D printer. By changing the rotation angle of the analyzer in front of the camera in the PSI system, the sensor detection sensitivity can be tuned. The proposed system may achieve high throughput as well as high sensitivity. The experimental results show that an optimal detection sensitivity of 6.82×10(-4)  RIU can be achieved.

  3. STRUCTURED LIGHT BASED 3D SCANNING FOR SPECULAR SURFACE BY THE COMBINATION OF GRAY CODE AND PHASE SHIFTING

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2016-06-01

    Full Text Available Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i A complete setup of the structured light based 3D scanning system; (ii A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the

  4. Observations of a quasi-coherent fluctuation mode in the KT-5C tokamak during -90 deg. phase shift feedback

    International Nuclear Information System (INIS)

    Zhai Kan; Wen Yizhi; Yu Changxuan; Liu Wandong; Wan Shude; Zhuang Ge; Yu Wen; Xu Zhizhan

    1997-01-01

    A new fluctuation phenomenon is observed through Langmuir probe measurements at the edge plasma in the KT-5C tokamak by applying a -90 deg. phase shift feedback. Using a two point correlation technique, it is found that this fluctuation mode has a longer poloidal wavelength and a definite frequency when compared with the usual edge turbulence. It is also found through bispectral analysis that this mode is a spontaneously excited quasi-coherent mode, which has almost no contribution to the cross-field particle flux. (author)

  5. First and second-order corrections to the eikonal phase shifts for the interactions of two deformed nuclei

    International Nuclear Information System (INIS)

    Metawei, Z.

    2000-01-01

    We present the first and second - order corrections to the eikonal phase shifts for the interactions of two deformed nuclei. The elastic scattering differential cross-section has been calculated for both the interactions of I2 C- 12 C system (at energies 1016, 1449 and 2400 MeV) and 16 O- 12 C system (at energy 1503 MeV). The calculated results corrections seems to improve the agreement with the experimental data.The deflection function, the S-matrix,the near-side and the far-side decompositions of the scattering amplitude has been calculated using the same corrections

  6. On the Pais-Treiman method to measure ππ phase shifts in Ke4 decays

    International Nuclear Information System (INIS)

    Colangelo, G.; Knecht, M.; Stern, J.

    1994-01-01

    Theoretical uncertainties of the method of Pais and Treiman to measure the ππ phase shifts in K e4 decays are estimated. It has been found that they are very small, below 1%. Newly planned experiments like KLOE at DAΦNE, will hopefully be able to reduce the errors sizeably enough to decide between the theoretical alternatives. In view of this improvement on the experimental side, it is worth to check what kind of uncertainties affect the Pais-Treiman method from the theoretical point of view. (authors). 12 refs., 1 fig

  7. All-optical Hilbert transformer based on a single phase-shifted fiber Bragg grating: design and analysis.

    Science.gov (United States)

    Asghari, Mohammad H; Azaña, José

    2009-02-01

    A simple all-fiber design for implementing an all-optical temporal Hilbert transformer is proposed and numerically demonstrated. We show that an all-optical Hilbert transformer can be implemented using a uniform-period fiber Bragg grating (FBG) with a properly designed amplitude-only grating apodization profile incorporating a single pi phase shift in the middle of the grating length. All-optical Hilbert transformers capable of processing arbitrary optical waveforms with bandwidths up to a few hundreds of gigahertz can be implemented using feasible FBGs.

  8. Nucleon-nucleon scattering phase shifts. [Resonance, 0 to 800 MeV, review

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, R.

    1978-01-01

    Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the /sup 1/D/sub 2/ and /sup 3/F/sub 3/ states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references.

  9. Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

    International Nuclear Information System (INIS)

    Prosnitz, D.; Scharlemann, E.T.; Sheaffer, M.K.

    1991-10-01

    Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by π radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple arguments

  10. A New Method for Parameterization of Phase Shift and Backscattering Amplitude

    NARCIS (Netherlands)

    Koningsberger, D.C.; Vaarkamp, M.; Linders, J.C.

    1995-01-01

    Parameterization of phase and backscattering amplitude with cubic splines is described. Using these cubic spline, the analytical partial derivatives of the plane wave EXAFS function can be calculated. The use of analytical partial derivatives decreases the CPU time needed for a refinement by over

  11. Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs.

    Science.gov (United States)

    Kriegisch, Nina; Reeves, Simon; Johnson, Craig R; Ling, Scott D

    2016-01-01

    Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) was manipulated over 12 months to estimate (1) the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2) the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia. In parallel, the role of one of the 'bottom-up' drivers of ecosystem structure was examined by (3) manipulating local nutrient levels and thus attempting to alter primary production on the experimental reefs. It was found that densities of 8 or more urchins m-2 (≥ 427 g m-2 biomass) lead to complete overgrazing of kelp beds while kelp bed recovery occurred when densities were reduced to ≤ 4 urchins m-2 (≤ 213 g m-2 biomass). This experiment provided further insight into the dynamics of transition between urchin barrens and kelp beds by exploring possible tipping-points which in this system can be found between 4 and 8 urchins m-2 (213 and 427 g m-2 respectively). Local enhancement of nutrient loading did not change the urchin density required for overgrazing or kelp bed recovery, as algal growth was not affected by nutrient enhancement.

  12. PV Power-Generation System with a Phase-Shift PWM Technique for High Step-Up Voltage Applications

    Directory of Open Access Journals (Sweden)

    Cheng-Tao Tsai

    2012-01-01

    Full Text Available A PV power-generation system with a phase-shift pulse-width modulation (PWM technique for high step-up voltage applications is proposed. The proposed power-generation system consists of two stages. In the input stage, all power switches of the full-bridge converter with phase-shift technique can be operated with zero-current switching (ZCS at turn-on or turn-off transition. Hence, the switching losses of the power switches can be reduced. Then, in the DC output stage, a voltage-doubler circuit is used to boost a high dc-link bus voltage. To supply a utility power, a dc/ac inverter is connected to induce a sinusoidal source. In order to draw a maximum power from PV arrays source, a microcontroller is incorporated with the perturbation and observation method to implement maximum power point tracking (MPPT algorithm and power regulating scheme. In this study, a full load power of 300 W prototype has been built. Experimental results are presented to verify the performance and feasibility of the proposed PV power-generation system.

  13. Catastrophic shifts in ecosystems: spatial early warnings and management procedures (Inspired in the physics of phase transitions)

    International Nuclear Information System (INIS)

    Ecosystems are complex systems which can respond to gradual changes of their conditions by a sudden shift to a contrasting regime or alternative stable state (ASS). Predicting such critical points before they are reached is extremely difficult and providing early warnings is fundamental to design management protocols for ecosystems. Here we study different spatial versions of popular ecological models which are known to exhibit ASS. The spatial heterogeneity is introduced by a local parameter varying from cell to cell in a regular lattice. Transport of biomass among cells occurs by simple diffusion. We investigate whether different quantities from statistical mechanics -like the variance, the two-point correlation function and the patchiness-may serve as early warnings of catastrophic phase transitions between the ASS. In particular, we find that the patch-size distribution follows a power law when the system is close to the catastrophic transition. We also provide links between spatial and temporal indicators and analyze how the interplay between diffusion and spatial heterogeneity may affect the earliness of each of the observables. Finally, we comment on similarities and differences between these catastrophic shifts and paradigmatic thermodynamic phase transitions like the liquid-vapor change of state for a fluid like water.

  14. Ovariectomy influences the circadian rhythm of locomotor activity and the photic phase shifts in the volcano mouse.

    Science.gov (United States)

    Juárez-Tapia, Cinthia; Miranda-Anaya, Manuel

    2017-12-01

    Recently, the relationship between the circadian system and female reproduction has been of great interest; ovarian hormones can modify the amount and distribution of daily activity differently in rodent species. The volcano mouse Neotomodon alstoni is a species in which it is possible to study the circadian rhythm of locomotion, and it offers comparative information about the influence of ovaries on the circadian system. In this study, we used infrared crossings to compare free movement in intact and sham-operated or ovariectomized mice. We analyzed behavioral and endocrine changes related to the estrous cycle and locomotor circadian rhythm in free-running mice and photic phase shifting. Evidence shows that intact mice present a scalloped pattern of daily activity during the estrous cycle. In constant darkness, the ovariectomy reduces the total amount of activity, shortens the free-running circadian period of locomotion and increases photic phase shifts during the early subjective night. During entrainment, the ovariectomized mice increased the amplitude of total activity during the scotophase, and delay the time of activity onset. These results suggest that ovarian hormones in N. alstoni modulate the circadian rhythm of locomotor activity in a species-specific manner. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. 3D phase-shifting fringe projection system on the basis of a tailored free-form mirror.

    Science.gov (United States)

    Zwick, Susanne; Heist, Stefan; Steinkopf, Ralf; Huber, Sandra; Krause, Sylvio; Bräuer-Burchardt, Christian; Kühmstedt, Peter; Notni, Gunther

    2013-05-10

    Phase-shifting fringe projection is an effective method to perform 3D shape measurements. Conventionally, fringe projection systems utilize a digital projector that images fringes into the measurement plane. The performance of such systems is limited to the visible spectral range, as most projectors experience technical limitations in UV or IR spectral ranges. However, for certain applications these spectral ranges are of special interest. We present a wideband fringe projector that has been developed on the basis of a picture generating beamshaping mirror. This mirror generates a sinusoidal fringe pattern in the measurement plane without any additional optical elements. Phase shifting is realized without any mechanical movement by a multichip LED. As the system is based on a single mirror, it is wavelength-independent in a wide spectral range and therefore applicable in UV and IR spectral ranges. We present the design and a realized setup of this fringe projection system and the characterization of the generated intensity distribution. Experimental results of 3D shape measurements are presented.

  16. On the nonexistence of degenerate phase-shift discrete solitons in a dNLS nonlocal lattice

    Science.gov (United States)

    Penati, T.; Sansottera, M.; Paleari, S.; Koukouloyannis, V.; Kevrekidis, P. G.

    2018-05-01

    We consider a one-dimensional discrete nonlinear Schrödinger (dNLS) model featuring interactions beyond nearest neighbors. We are interested in the existence (or nonexistence) of phase-shift discrete solitons, which correspond to four-site vortex solutions in the standard two-dimensional dNLS model (square lattice), of which this is a simpler variant. Due to the specific choice of lengths of the inter-site interactions, the vortex configurations considered present a degeneracy which causes the standard continuation techniques to be non-applicable. In the present one-dimensional case, the existence of a conserved quantity for the soliton profile (the so-called density current), together with a perturbative construction, leads to the nonexistence of any phase-shift discrete soliton which is at least C2 with respect to the small coupling ɛ, in the limit of vanishing ɛ. If we assume the solution to be only C0 in the same limit of ɛ, nonexistence is instead proved by studying the bifurcation equation of a Lyapunov-Schmidt reduction, expanded to suitably high orders. Specifically, we produce a nonexistence criterion whose efficiency we reveal in the cases of partial and full degeneracy of approximate solutions obtained via a leading order expansion.

  17. Comparison Between DNS Data and Resolvent Model Prediction of Opposition Control with a Phase Shift Between Sensor and Actuator

    Science.gov (United States)

    Toedtli, Simon; Luhar, Mitul; McKeon, Beverley

    2017-11-01

    In a recent study, Luhar et al. analyzed the opposition control scheme within the resolvent analysis framework and demonstrated that their low-order model is able to qualitatively reproduce results from previous direct numerical simulation (DNS) studies. The model further predicts that introducing a phase shift between the sensor measurement and the actuator response strongly affects the attainable drag reduction and has the potential to improve the control effectiveness. The present study validates these predictions by means of a parametric DNS study and demonstrates that the response of the full nonlinear system to opposition control with various phase shifts between sensor and actuator very closely follows the low-order model. The good agreement between model prediction and DNS demonstrates for the first time the predictive capabilities of the resolvent analysis framework and suggests that it is a suitable low-order model to systematically design and optimize flow control schemes. This work is made possible by the Air Force Office of Scientific Research through AFOSR Grant Number FA 9550-16-1-0361.

  18. Battery Internal Temperature Estimation for LiFePO4 Battery Based on Impedance Phase Shift under Operating Conditions

    Directory of Open Access Journals (Sweden)

    Jiangong Zhu

    2017-01-01

    Full Text Available An impedance-based temperature estimation method is investigated considering the electrochemical non-equilibrium with short-term relaxation time for facilitating the vehicular application. Generally, sufficient relaxation time is required for battery electrochemical equilibrium before the impedance measurement. A detailed experiment is performed to investigate the regularity of the battery impedance in short-term relaxation time after switch-off current excitation, which indicates that the impedance can be measured and also has systematical decrement with the relaxation time growth. Based on the discussion of impedance variation in electrochemical perspective, as well as the monotonic relationship between impedance phase shift and battery internal temperature in the electrochemical equilibrium state, an exponential equation that accounts for both measured phase shift and relaxation time is established to correct the measuring deviation caused by electrochemical non-equilibrium. Then, a multivariate linear equation coupled with ambient temperature is derived considering the temperature gradients between the active part and battery surface. Equations stated above are all identified with the embedded thermocouple experimentally. In conclusion, the temperature estimation method can be a valuable alternative for temperature monitoring during cell operating, and serve the functionality as an efficient implementation in battery thermal management system for electric vehicles (EVs and hybrid electric vehicles (HEVs.

  19. Catastrophic shifts in ecosystems: spatial early warnings and management procedures (Inspired in the physics of phase transitions)

    Energy Technology Data Exchange (ETDEWEB)

    Fort, H [Complex Systems Group, Instituto de Fisica, Facultad de Ciencias, Universidad de la Republica, Igua 4225, 11400 Montevideo (Uruguay); Mazzeo, N [Depto. de EcologIa, Facultad de Ciencias, Universidad de la Republica, Igua 4225, 11400 Montevideo (Uruguay); Scheffer, M; Nes, E van, E-mail: hugo@fisica.edu.u [Wageningen Agricultural University, Aquatic Ecology and Water Quality Management Group, PO Box 47, 6700 AA Wageningen (Netherlands)

    2010-09-01

    Ecosystems are complex systems which can respond to gradual changes of their conditions by a sudden shift to a contrasting regime or alternative stable state (ASS). Predicting such critical points before they are reached is extremely difficult and providing early warnings is fundamental to design management protocols for ecosystems. Here we study different spatial versions of popular ecological models which are known to exhibit ASS. The spatial heterogeneity is introduced by a local parameter varying from cell to cell in a regular lattice. Transport of biomass among cells occurs by simple diffusion. We investigate whether different quantities from statistical mechanics -like the variance, the two-point correlation function and the patchiness-may serve as early warnings of catastrophic phase transitions between the ASS. In particular, we find that the patch-size distribution follows a power law when the system is close to the catastrophic transition. We also provide links between spatial and temporal indicators and analyze how the interplay between diffusion and spatial heterogeneity may affect the earliness of each of the observables. Finally, we comment on similarities and differences between these catastrophic shifts and paradigmatic thermodynamic phase transitions like the liquid-vapor change of state for a fluid like water.

  20. Optimized fringe patterns based on dual-frequency phase-shift technology in fringe projection profilometry

    Science.gov (United States)

    Yu, Hao; Lin, Liangzhao; Li, Xiaoying; Lu, Xiaoxu; Zhong, Liyun; Liu, Shengde

    2017-09-01

    A look-up table (LUT) method for solving the problem of phase unwrapping is presented. Considering the effect of noise on the unwrapping process, a concept called "tolerance" is advanced, and an associated algorithm called the "equipartition of tolerance" algorithm is proposed. The proposed algorithm eliminates the need for a high signal-to-noise ratio while retaining the LUT method's advantages of extended measurement range and high precision. Further, it improves the tolerance of the LUT method and enables reconstruction of discontinuous objects. In simulations and experiments conducted, the proposed algorithm successfully unwrapped the absolute phase of a slope model and a three-step model. The proposed algorithm is significantly more accurate and has better stability and sensitivity than the heterodyne algorithm.

  1. A 16-channel reconfigurable OCDMA/DWDM system using continuous phase-shift SSFBGs

    OpenAIRE

    Chun, Tian; Zhang, Zhaowei; Ibsen, M.; Petropoulos, P.; Richardson, D.J.

    2007-01-01

    We demonstrate a reconfigurable 16-channel optical code-division multiple access (OCDMA)/dense wavelength division multiplexing (DWDM) system (4 OCDMA times 4 DWDM times 625 Mb/s) based on novel 31-chip, 40 Gchip/s quaternary phase coding gratings operating at a channel spacing of just 50 GHz. The system performance is studied for cases of both fixed and code-reconfigurable decoders. Error-free performance is achieved in both cases and for all 16 channels.

  2. Redox homeostasis and reactive oxygen species scavengers shift during ontogenetic phase changes in apple.

    Science.gov (United States)

    Du, Zhen; Jia, Xiao Lin; Wang, Yi; Wu, Ting; Han, Zhen Hai; Zhang, Xin Zhong

    2015-07-01

    The change from juvenile to adult phase is a universal phenomenon in perennial plants such as apple. To validate the changes in hydrogen peroxide (H2O2) levels and scavenging during ontogenesis in apple seedlings, the H2O2 contents, its scavenging capacity, and the expression of related genes, as well as miR156 levels, were measured in leaf samples from different nodes in seedlings of 'Zisai Pearl' (Malus asiatica)×'Red Fuji' (M. domestica). Then in vitro shoots were treated with redox modulating chemicals to verify the response of miR156 to redox alteration. The expression of miR156 decreased gradually during ontogenesis, indicating a progressive loss of juvenility. During the phase changes, H2O2 and ascorbate contents, the ratio of ascorbate to dehydroascorbate, the ascorbate peroxidase, catalase and glutathione reductase activities, and the expressions of some MdGR and MdAPX gene family members increased remarkably. However, the glutathione content and glutathione to glutathione disulfide ratio declined. In chemicals treated in vitro shoots, the changes in miR156 levels were coordinated with GSH contents and GSH/GSSG ratio but not H2O2 contents. Conclusively, the relative reductive thiol redox status is critical for the maintenance of juvenility and the reductive ascorbate redox environment was elevated and sustained during the reproductive phase. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Simulated body temperature rhythms reveal the phase-shifting behavior and plasticity of mammalian circadian oscillators

    Science.gov (United States)

    Saini, Camille; Morf, Jörg; Stratmann, Markus; Gos, Pascal; Schibler, Ueli

    2012-01-01

    The circadian pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus maintains phase coherence in peripheral cells through metabolic, neuronal, and humoral signaling pathways. Here, we investigated the role of daily body temperature fluctuations as possible systemic cues in the resetting of peripheral oscillators. Using precise temperature devices in conjunction with real-time monitoring of the bioluminescence produced by circadian luciferase reporter genes, we showed that simulated body temperature cycles of mice and even humans, with daily temperature differences of only 3°C and 1°C, respectively, could gradually synchronize circadian gene expression in cultured fibroblasts. The time required for establishing the new steady-state phase depended on the reporter gene, but after a few days, the expression of each gene oscillated with a precise phase relative to that of the temperature cycles. Smooth temperature oscillations with a very small amplitude could synchronize fibroblast clocks over a wide temperature range, and such temperature rhythms were also capable of entraining gene expression cycles to periods significantly longer or shorter than 24 h. As revealed by genetic loss-of-function experiments, heat-shock factor 1 (HSF1), but not HSF2, was required for the efficient synchronization of fibroblast oscillators to simulated body temperature cycles. PMID:22379191

  4. Simulated body temperature rhythms reveal the phase-shifting behavior and plasticity of mammalian circadian oscillators.

    Science.gov (United States)

    Saini, Camille; Morf, Jörg; Stratmann, Markus; Gos, Pascal; Schibler, Ueli

    2012-03-15

    The circadian pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus maintains phase coherence in peripheral cells through metabolic, neuronal, and humoral signaling pathways. Here, we investigated the role of daily body temperature fluctuations as possible systemic cues in the resetting of peripheral oscillators. Using precise temperature devices in conjunction with real-time monitoring of the bioluminescence produced by circadian luciferase reporter genes, we showed that simulated body temperature cycles of mice and even humans, with daily temperature differences of only 3°C and 1°C, respectively, could gradually synchronize circadian gene expression in cultured fibroblasts. The time required for establishing the new steady-state phase depended on the reporter gene, but after a few days, the expression of each gene oscillated with a precise phase relative to that of the temperature cycles. Smooth temperature oscillations with a very small amplitude could synchronize fibroblast clocks over a wide temperature range, and such temperature rhythms were also capable of entraining gene expression cycles to periods significantly longer or shorter than 24 h. As revealed by genetic loss-of-function experiments, heat-shock factor 1 (HSF1), but not HSF2, was required for the efficient synchronization of fibroblast oscillators to simulated body temperature cycles.

  5. Warm Water Bath Stimulates Phase-Shifts of the Peripheral Circadian Clocks in PER2::LUCIFERASE Mouse

    Science.gov (United States)

    Kuriki, Daisuke; Haraguchi, Atsushi; Shibata, Shigenobu

    2014-01-01

    Circadian clocks in the peripheral tissues of mice are known to be entrained by pulse stimuli such as restricted feeding, novel wheel running, and several other agents. However, there are no reports on high temperature pulse-mediated entrainment on the phase-shift of peripheral clocks in vivo. Here we show that temperature treatment of mice for two days at 41°C, instead of 37°C, for 1–2 h during the inactive period, using a temperature controlled water bath stimulated phase-advance of peripheral clocks in the kidney, liver, and submandibular gland of PER2::LUCIFERASE mice. On the other hand, treatment for 2 days at 35°C ambient room temperature for 2 h did not cause a phase-advance. Maintenance of mice at 41°C in a water bath, sustained the core body temperature at 40–41°C. However, the use of 37°C water bath or the 35°C ambient room temperature elevated the core body temperature to 38.5°C, suggesting that at least a core body temperature of 40–41°C is necessary to cause phase-advance under light-dark cycle conditions. The temperature pulse stimulation at 41°C, instead of 37°C water bath for 2 h led to the elevated expression of Per1 and Hsp70 in the peripheral tissue of mice. In summary, the present study demonstrates that transient high temperature pulse using water bath during daytime causes phase-advance in mouse peripheral clocks in vivo. The present results suggest that hot water bath may affect the phase of peripheral clocks. PMID:24933288

  6. 3D mouse shape reconstruction based on phase-shifting algorithm for fluorescence molecular tomography imaging system.

    Science.gov (United States)

    Zhao, Yue; Zhu, Dianwen; Baikejiang, Reheman; Li, Changqing

    2015-11-10

    This work introduces a fast, low-cost, robust method based on fringe pattern and phase shifting to obtain three-dimensional (3D) mouse surface geometry for fluorescence molecular tomography (FMT) imaging. We used two pico projector/webcam pairs to project and capture fringe patterns from different views. We first calibrated the pico projectors and the webcams to obtain their system parameters. Each pico projector/webcam pair had its own coordinate system. We used a cylindrical calibration bar to calculate the transformation matrix between these two coordinate systems. After that, the pico projectors projected nine fringe patterns with a phase-shifting step of 2π/9 onto the surface of a mouse-shaped phantom. The deformed fringe patterns were captured by the corresponding webcam respectively, and then were used to construct two phase maps, which were further converted to two 3D surfaces composed of scattered points. The two 3D point clouds were further merged into one with the transformation matrix. The surface extraction process took less than 30 seconds. Finally, we applied the Digiwarp method to warp a standard Digimouse into the measured surface. The proposed method can reconstruct the surface of a mouse-sized object with an accuracy of 0.5 mm, which we believe is sufficient to obtain a finite element mesh for FMT imaging. We performed an FMT experiment using a mouse-shaped phantom with one embedded fluorescence capillary target. With the warped finite element mesh, we successfully reconstructed the target, which validated our surface extraction approach.

  7. Absolute determination of zero-energy phase shifts for multiparticle single-channel scattering: Generalized Levinson theorem

    International Nuclear Information System (INIS)

    Rosenberg, L.; Spruch, L.

    1996-01-01

    Levinson close-quote s theorem relates the zero-energy phase shift δ for potential scattering in a given partial wave l, by a spherically symmetric potential that falls off sufficiently rapidly, to the number of bound states of that l supported by the potential. An extension of this theorem is presented that applies to single-channel scattering by a compound system initially in its ground state. As suggested by Swan [Proc. R. Soc. London Ser. A 228, 10 (1955)], the extended theorem differs from that derived for potential scattering; even in the absence of composite bound states δ may differ from zero as a consequence of the Pauli principle. The derivation given here is based on the introduction of a continuous auxiliary open-quote open-quote length phase close-quote close-quote η, defined modulo π for l=0 by expressing the scattering length as A=acotη, where a is a characteristic length of the target. Application of the minimum principle for the scattering length determines the branch of the cotangent curve on which η lies and, by relating η to δ, an absolute determination of δ is made. The theorem is applicable, in principle, to single-channel scattering in any partial wave for e ± -atom and nucleon-nucleus systems. In addition to a knowledge of the number of composite bound states, information (which can be rather incomplete) concerning the structure of the target ground-state wave function is required for an explicit, absolute, determination of the phase shift δ. As for Levinson close-quote s original theorem for potential scattering, no additional information concerning the scattering wave function or scattering dynamics is required. copyright 1996 The American Physical Society

  8. Correction of susceptibility-induced GRE phase shift for accurate PRFS thermometry proximal to cryoablation iceball.

    Science.gov (United States)

    Kickhefel, Antje; Weiss, Clifford; Roland, Joerg; Gross, Patrick; Schick, Fritz; Salomir, Rares

    2012-02-01

    The susceptibility contrast between frozen and unfrozen tissue disturbs the local magnetic field in the proximity of the ice-ball during cryotherapy. This effect should be corrected for in real time to allow PRFS-based monitoring of near-zero temperatures during intervention. Susceptibility artifacts were corrected post-processing, using a rapid numerical algorithm. The difference in bulk magnetic susceptibility between frozen and non-frozen tissue was approximated to be uniform over the ice-ball volume and was determined from the isothermal principle applied to the phase-transition frontier of compartments. Subsequently, the magnetic perturbation field was calculated rapidly in 3D using a Fourier-convolution. Experimental studies were performed for two scenarios: tissue defrosting in a water bath and induction of an ice-ball by a MR-compatible cryogenic probe. The susceptibility artifacts yielded PRFS temperature errors as high as 10-12°C proximal to the ice-ball, positive or negative depending on the relative orientation of the position vector from the B(o) direction. These effects were fully corrected for to within the noise range. The susceptibility-corrected PRFS temperature values were consistent with the phase-transition isothermal condition, irrespective of the local orientation of the position vector. By implementing on-line the post processing algorithm, PRFS MRT may be used as a safety tool for non-invasive and accurate monitoring of near-zero temperatures during MR-guided clinical cryotherapy.

  9. Coral-macroalgal phase shifts or reef resilience: links with diversity and functional roles of herbivorous fishes on the Great Barrier Reef

    Science.gov (United States)

    Cheal, A. J.; MacNeil, M. Aaron; Cripps, E.; Emslie, M. J.; Jonker, M.; Schaffelke, B.; Sweatman, H.

    2010-12-01

    Changes from coral to macroalgal dominance following disturbances to corals symbolize the global degradation of coral reefs. The development of effective conservation measures depends on understanding the causes of such phase shifts. The prevailing view that coral-macroalgal phase shifts commonly occur due to insufficient grazing by fishes is based on correlation with overfishing and inferences from models and small-scale experiments rather than on long-term quantitative field studies of fish communities at affected and resilient sites. Consequently, the specific characteristics of herbivorous fish communities that most promote reef resilience under natural conditions are not known, though this information is critical for identifying vulnerable ecosystems. In this study, 11 years of field surveys recorded the development of the most persistent coral-macroalgal phase shift (>7 years) yet observed on Australia’s Great Barrier Reef (GBR). This shift followed extensive coral mortality caused by thermal stress (coral bleaching) and damaging storms. Comparisons with two similar reefs that suffered similar disturbances but recovered relatively rapidly demonstrated that the phase shift occurred despite high abundances of one herbivore functional group (scraping/excavating parrotfishes: Labridae). However, the shift was strongly associated with low fish herbivore diversity and low abundances of algal browsers (predominantly Siganidae) and grazers/detritivores (Acanthuridae), suggesting that one or more of these factors underpin reef resilience and so deserve particular protection. Herbivorous fishes are not harvested on the GBR, and the phase shift was not enhanced by unusually high nutrient levels. This shows that unexploited populations of herbivorous fishes cannot ensure reef resilience even under benign conditions and suggests that reefs could lose resilience under relatively low fishing pressure. Predictions of more severe and widespread coral mortality due to global

  10. Molecular dynamics with phase-shift-based electronic stopping for calibration of ion implantation profiles in crystalline silicon

    International Nuclear Information System (INIS)

    Chan, H.Y.; Nordlund, K.; Gossmann, H.-J.L.; Harris, M.; Montgomery, N.J.; Mulcahy, C.P.A.; Biswas, S.; Srinivasan, M.P.; Benistant, F.; Ng, C.M.; Chan, Lap

    2006-01-01

    Prediction of the final dopant positions after ion implantation has always been strongly influenced by the choice of stopping models. A molecular dynamics (MD) method is used in this work; the nuclear stopping is treated by accurate pair potentials calculated by density functional theory (DFT). The slowing down due to collisions with electrons will be described by both a non-local semi-empirical model and a local model based on Fermi level phase shift factors. Comparisons with experimental data using both models show that a local pair-specific electronic stopping model is essential in accurately predicting range profiles for any element even at low implant energies where nuclear effects are dominant

  11. New high statistics measurement of $K_{e4}$ decay form factors and $\\pi \\pi$ scattering phase shifts

    CERN Document Server

    Batley, J Richard; Kalmus, George Ernest; Lazzeroni, C; Munday, D J; Slater, M W; Wotton, S A; Arcidiacono, R; Bocquet, G; Cabibbo, Nicola; Ceccucci, A; Cundy, Donald C; Falaleev, V; Fidecaro, Maria; Gatignon, L; Gonidec, A; Kubischta, Werner; Norton, A; Maier, A; Patel, M; Peters, A; Balev, S; Frabetti, P L; Goudzovski, E; Khristov, P Z; Kekelidze, V; Kozhuharov, V; Litov, L; Madigozhin, D T; Marinova, E; Molokanova, N; Polenkevich, I; Potrebenikov, Yu; Stoynev, S; Zinchenko, A; Monnier, E; Swallow, E; Winston, R; Rubin, P; Walker, A; Baldini, W; Cotta-Ramusino, A; Dalpiaz, P; Damiani, C; Fiorini, M; Gianoli, A; Martini, M; Petrucci, F; Savrié, M; Scarpa, M; Wahle, H; Bizzeti, A; Calvetti, M; Celeghini, E; Iacopini, E; Lenti, M; Martelli, F; Ruggiero, G; Veltri, M; Behler, M; Eppard, K; Kleinknecht, K; Marouelli, P; Masetti, L; Moosbrugger, U; Morales-Morales, C; Renk, B; Wache, M; Wanke, R; Winhart, A; Coward, D; Dabrowski, A; Fonseca-Martin, T; Shieh, M; Szleper, M; Velasco, M; Wood, M D; Anzivino, Giuseppina; Cenci, P; Imbergamo, E; Nappi, A; Pepé, M; Petrucci, M C; Piccini, M; Raggi, M; Valdata-Nappi, M; Cerri, C; Collazuol, G; Costantini, F; Di Lella, L; Doble, N; Fantechi, R; Fiorini, L; Giudici, S; Lamanna, G; Mannelli, I; Michetti, A; Pierazzini, G; Sozzi, M; Bloch-Devaux, B; Cheshkov, C; Chèze, J B; De Beer, M; Derré, J; Marel, Gérard; Mazzucato, E; Peyaud, B; Vallage, B; Holder, M; Ziolkowski, M; Bifani, S; Biino, C; Cartiglia, N; Clemencic, M; Goy-Lopez, S; Marchetto, F; Dibon, Heinz; Jeitler, Manfred; Markytan, Manfred; Mikulec, I; Neuhofer, G; Widhalm, L

    2008-01-01

    We report results from a new measurement of the K_{e4} decay K^{+-} -> \\pi^+ \\pi^- e^{+-} v by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F, G, H) and pi pi scattering phase shift delta00-delta11 have been measured using a model-independent method and their variation with the pi pi mass has been investigated. Thanks to a sizeable acceptance at large pi pi mass, a low background and a very good resolution, an improved accuracy (+- 0.006 stat +- 0.002 syst), a factor two better than in the previous measurement, is reached when extracting the pi pi scattering length a00.

  12. Quark-diquark approximation of the three-quark structure of a nucleon and the NN phase shifts

    International Nuclear Information System (INIS)

    Efimov, G.V.; Ivanov, M.A.

    1988-01-01

    The quark-diquark approximations of the three-quark structure of a nucleon are considered in the framework of the quark confinement model (QCM) based on definite concepts of the hadronization and quark confinement. The static nucleon characteristics (magnetic moments, ratio G A /G V and strong meson-nucleon coupling constants) are calculated. The behaviour of the electromagnetic and strong nucleon form factors is obtained at the low energy (0≤0 2 =-q 2 2 , where q is a transfer momentum). The one-boson exchange potential is constructed and the NN-phase-shifts are computed. Our results are compared with experiment and the Bonn potential model. 45 refs.; 7 figs.; 3 tabs

  13. Influence of Camera Setting on Vehicle-to-Vehicle VLC Employing Undersampled Phase Shift On-Off Keying

    Directory of Open Access Journals (Sweden)

    S. Vitek

    2017-12-01

    Full Text Available This paper focuses on the performance analysis of a camera based vehicle-to-vehicle visible light communication system employing undersampled phase shift on-off keying modulation under interference scenario. Two Nissan Qashqai front lights with daylight running light emitting diodes based lamps are used for communications. The bit error rate (BER performance of the proposed system is experimentally measured for a transmission span up to 24m focusing mostly on the side interference due to reflections. Based on experimental data we demonstrate reduction of the system performance due to the side reflection and illumination of the detector by other light sources which has to taken into account during further data processing. We provide with further statistics for particular shuter speed and transmitter power setting and discus BER improvement especially to meet FEC via the method of adaptive region of interest.

  14. Impedance self-matching ultra-narrow linewidth fiber resonator by use of a tunable π-phase-shifted FBG.

    Science.gov (United States)

    Jing, Mingyong; Yu, Bo; Hu, Jianyong; Hou, Huifang; Zhang, Guofeng; Xiao, Liantuan; Jia, Suotang

    2017-05-15

    In this paper, we present a novel ultra-narrow linewidth fiber resonator formed by a tunable polarization maintaining (PM) π-phase-shifted fiber Bragg grating and a PM uniform fiber Bragg grating with a certain length of PM single mode fiber patch cable between them. Theoretical prediction shows that this resonator has ultra-narrow linewidth resonant peaks and is easy to realize impedance matching. We experimentally obtain 3 MHz narrow linewidth impedance matched resonant peak in a 7.3 m ultra-long passive fiber cavity. The impedance self-matching characteristic of this resonator also makes itself particularly suitable for use in ultra-sensitive sensors, ultra-narrow band rejection optical filters and fiber lasers applications.

  15. Voltage-Balancing Method for Modular Multilevel Converters Under Phase-Shifted Carrier-Based Pulsewidth Modulation

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2015-01-01

    The modular multilevel converter (MMC) becomes attractive for medium- or high-power applications because of the advantages of high modularity, availability, and power quality. One of the technical challenges associated with an MMC is the balancing of the capacitors' voltages. In this paper......, a voltage-balancing control method is proposed for the MMC under phase-shifted carrier-based pulsewidth modulation. The proposed voltage-balancing method uses the linearization method for pulse sorting without arm current measurement, which can control the capacitor charge transfer to balance the capacitor....../EMTDC are conducted, and a downscale MMC prototype is also tested with the proposed method. The study results show the effectiveness of the proposed voltage-balancing method....

  16. Vibration of nonuniform carbon nanotube with attached mass via nonlocal Timoshenko beam theory

    International Nuclear Information System (INIS)

    Tang, Hai Li; Shen, Zhi Bin; Li, Dao Kui

    2014-01-01

    This paper studies the vibrational behavior of nonuniform single-walled carbon nanotube (SWCNT) carrying a nanoparticle. A nonuniform cantilever beam with a concentrated mass at the free end is analyzed according to the nonlocal Timoshenko beam theory. A governing equation of a nonuniform SWCNT with attached mass is established. The transfer function method incorporating with the perturbation method is utilized to obtain the resonant frequencies of a vibrating nonlocal cantilever-mass system. The effects of the nonlocal parameter, taper ratio and attached mass on the natural frequencies and frequency shifts are discussed. Obtained results indicate that the sensitivity of the frequency shifts on the attached mass increases when the length-to-diameter ratio decreases. Tapered SWCNT possesses higher fundamental frequencies if the taper ratio becomes larger.

  17. Characterisation of the maternal response to chronic phase shifts during gestation in the rat: implications for fetal metabolic programming.

    Directory of Open Access Journals (Sweden)

    Tamara J Varcoe

    Full Text Available Disrupting maternal circadian rhythms through exposure to chronic phase shifts of the photoperiod has lifelong consequences for the metabolic homeostasis of the fetus, such that offspring develop increased adiposity, hyperinsulinaemia and poor glucose and insulin tolerance. In an attempt to determine the mechanisms by which these poor metabolic outcomes arise, we investigated the impact of chronic phase shifts (CPS on maternal and fetal hormonal, metabolic and circadian rhythms. We assessed weight gain and food consumption of dams exposed to either CPS or control lighting conditions throughout gestation. At day 20, dams were assessed for plasma hormone and metabolite concentrations and glucose and insulin tolerance. Additionally, the expression of a range of circadian and metabolic genes was assessed in maternal, placental and fetal tissue. Control and CPS dams consumed the same amount of food, yet CPS dams gained 70% less weight during the first week of gestation. At day 20, CPS dams had reduced retroperitoneal fat pad weight (-15%, and time-of-day dependent decreases in liver weight, whereas fetal and placental weight was not affected. Melatonin secretion was not altered, yet the timing of corticosterone, leptin, glucose, insulin, free fatty acids, triglycerides and cholesterol concentrations were profoundly disrupted. The expression of gluconeogenic and circadian clock genes in maternal and fetal liver became either arrhythmic or were in antiphase to the controls. These results demonstrate that disruptions of the photoperiod can severely disrupt normal circadian profiles of plasma hormones and metabolites, as well as gene expression in maternal and fetal tissues. Disruptions in the timing of food consumption and the downstream metabolic processes required to utilise that food, may lead to reduced efficiency of growth such that maternal weight gain is reduced during early embryonic development. It is these perturbations that may contribute to

  18. Characterisation of the maternal response to chronic phase shifts during gestation in the rat: implications for fetal metabolic programming.

    Science.gov (United States)

    Varcoe, Tamara J; Boden, Michael J; Voultsios, Athena; Salkeld, Mark D; Rattanatray, Leewen; Kennaway, David J

    2013-01-01

    Disrupting maternal circadian rhythms through exposure to chronic phase shifts of the photoperiod has lifelong consequences for the metabolic homeostasis of the fetus, such that offspring develop increased adiposity, hyperinsulinaemia and poor glucose and insulin tolerance. In an attempt to determine the mechanisms by which these poor metabolic outcomes arise, we investigated the impact of chronic phase shifts (CPS) on maternal and fetal hormonal, metabolic and circadian rhythms. We assessed weight gain and food consumption of dams exposed to either CPS or control lighting conditions throughout gestation. At day 20, dams were assessed for plasma hormone and metabolite concentrations and glucose and insulin tolerance. Additionally, the expression of a range of circadian and metabolic genes was assessed in maternal, placental and fetal tissue. Control and CPS dams consumed the same amount of food, yet CPS dams gained 70% less weight during the first week of gestation. At day 20, CPS dams had reduced retroperitoneal fat pad weight (-15%), and time-of-day dependent decreases in liver weight, whereas fetal and placental weight was not affected. Melatonin secretion was not altered, yet the timing of corticosterone, leptin, glucose, insulin, free fatty acids, triglycerides and cholesterol concentrations were profoundly disrupted. The expression of gluconeogenic and circadian clock genes in maternal and fetal liver became either arrhythmic or were in antiphase to the controls. These results demonstrate that disruptions of the photoperiod can severely disrupt normal circadian profiles of plasma hormones and metabolites, as well as gene expression in maternal and fetal tissues. Disruptions in the timing of food consumption and the downstream metabolic processes required to utilise that food, may lead to reduced efficiency of growth such that maternal weight gain is reduced during early embryonic development. It is these perturbations that may contribute to the programming of

  19. Circadian phase-shifting effects of a laboratory environment: a clinical trial with bright and dim light

    Directory of Open Access Journals (Sweden)

    Elliott Jeffrey A

    2005-09-01

    Full Text Available Abstract Background Our aims were to examine the influence of different bright light schedules on mood, sleep, and circadian organization in older adults (n = 60, ages 60–79 years with insomnia and/or depression, contrasting with responses of young, healthy controls (n = 30, ages 20–40 years. Methods Volunteers were assessed for one week in their home environments. Urine was collected over two 24-hour periods to establish baseline acrophase of 6-sulphatoxymelatonin (aMT6s excretion. Immediately following home recording, volunteers spent five nights and four days in the laboratory. Sleep periods were fixed at eight hours in darkness, consistent with the volunteers' usual sleep periods. Volunteers were randomly assigned to one of three light treatments (four hours per day within the wake period: (A two hours of 3,000 lux at 1–3 hours and 13–15 hours after arising; (B four hours of 3,000 lux at 6–10 hours after arising; (C four hours of dim placebo light at 6–10 hours after arising. Lighting was 50 lux during the remainder of wakefulness. The resulting aMT6s acrophase was determined during the final 30 hours in the laboratory. Results Neither mood nor total melatonin excretion differed significantly by treatment. For the three light treatments, significant and similar phase-response plots were found, indicating that the shift in aMT6s acrophase was dependent upon the circadian time of treatment. The changes in circadian timing were not significantly correlated to changes in sleep or mood. Conclusion The trial failed to demonstrate photoperiodic effects. The results suggest that even low levels of illumination and/or fixed timing of behavior had significant phase-shifting effects.

  20. Haldane model under nonuniform strain

    Science.gov (United States)

    Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.

    2017-10-01

    We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.

  1. Electrical system for pulse-width modulated control of a power inverter using phase-shifted carrier signals and related operating methods

    Science.gov (United States)

    Welchko, Brian A [Torrance, CA

    2012-02-14

    Systems and methods are provided for pulse-width modulated control of power inverter using phase-shifted carrier signals. An electrical system comprises an energy source and a motor. The motor has a first set of windings and a second set of windings, which are electrically isolated from each other. An inverter module is coupled between the energy source and the motor and comprises a first set of phase legs coupled to the first set of windings and a second set of phase legs coupled to the second set of windings. A controller is coupled to the inverter module and is configured to achieve a desired power flow between the energy source and the motor by modulating the first set of phase legs using a first carrier signal and modulating the second set of phase legs using a second carrier signal. The second carrier signal is phase-shifted relative to the first carrier signal.

  2. High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors.

    Science.gov (United States)

    March, Carmen; García, José V; Sánchez, Ángel; Arnau, Antonio; Jiménez, Yolanda; García, Pablo; Manclús, Juan J; Montoya, Ángel

    2015-03-15

    In spite of being widely used for in liquid biosensing applications, sensitivity improvement of conventional (5-20MHz) quartz crystal microbalance (QCM) sensors remains an unsolved challenging task. With the help of a new electronic characterization approach based on phase change measurements at a constant fixed frequency, a highly sensitive and versatile high fundamental frequency (HFF) QCM immunosensor has successfully been developed and tested for its use in pesticide (carbaryl and thiabendazole) analysis. The analytical performance of several immunosensors was compared in competitive immunoassays taking carbaryl insecticide as the model analyte. The highest sensitivity was exhibited by the 100MHz HFF-QCM carbaryl immunosensor. When results were compared with those reported for 9MHz QCM, analytical parameters clearly showed an improvement of one order of magnitude for sensitivity (estimated as the I50 value) and two orders of magnitude for the limit of detection (LOD): 30μgl(-1) vs 0.66μgL(-1)I50 value and 11μgL(-1) vs 0.14μgL(-1) LOD, for 9 and 100MHz, respectively. For the fungicide thiabendazole, I50 value was roughly the same as that previously reported for SPR under the same biochemical conditions, whereas LOD improved by a factor of 2. The analytical performance achieved by high frequency QCM immunosensors surpassed those of conventional QCM and SPR, closely approaching the most sensitive ELISAs. The developed 100MHz QCM immunosensor strongly improves sensitivity in biosensing, and therefore can be considered as a very promising new analytical tool for in liquid applications where highly sensitive detection is required. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. All-optical sensitive phase shifting based on nonlinear out-of-plane coupling through 1-D slab photonic crystal with a layer of graphene.

    Science.gov (United States)

    Asadi, Reza; Ouyang, Zhengbiao; Yu, Quanqiang; Ruan, Shuangchen

    2014-06-16

    We realize all-optical sensitive phase shifting based on nonlinear out-of-plane coupling to a slab waveguide through Fano resonance of a slab 1-D photonic crystal (PhC). We use a graphene layer as the nonlinear material and change its refractive index by the input light intensity through Kerr nonlinear effect to obtain a shift in the Fano resonance frequency. The Fano resonance and self-focusing effect lead to light-intensity enhancement on the graphene in the PhC, reinforcing the nonlinear effect of refractive index in the graphene. Through finite-difference time-domain simulation, we demonstrate that the phase changing sensitivity obtained can be 4 orders higher than that by a single graphene under the same input light intensity. Moreover the threshold pump intensity for all-optical sensitive phase shifting in the coupled light to the waveguide is as low as ~4 MW per square centimeter. The results are applicable in micro optical integrated circuits for phase shifters, phase modulators, power limiters, and phase logic elements for optical computation, digital phase shift keying in communication systems, and non-contact sensitive signal detectors.

  4. Wafer-based aberration metrology for lithographic systems using overlay measurements on targets imaged from phase-shift gratings.

    Science.gov (United States)

    van Haver, Sven; Coene, Wim M J; D'havé, Koen; Geypen, Niels; van Adrichem, Paul; de Winter, Laurens; Janssen, Augustus J E M; Cheng, Shaunee

    2014-04-20

    In this paper, a new methodology is presented to derive the aberration state of a lithographic projection system from wafer metrology data. For this purpose, new types of phase-shift gratings (PSGs) are introduced, with special features that give rise to a simple linear relation between the PSG image displacement and the phase aberration function of the imaging system. By using the PSGs as the top grating in a diffraction-based overlay stack, their displacement can be measured as an overlay error using a standard wafer metrology tool. In this way, the overlay error can be used as a measurand based on which the phase aberration function in the exit pupil of the lithographic system can be reconstructed. In practice, the overlay error is measured for a set of different PSG targets, after which this information serves as input to a least-squares optimization problem that, upon solving, provides estimates for the Zernike coefficients describing the aberration state of the lithographic system. In addition to a detailed method description, this paper also deals with the additional complications that arise when the method is implemented experimentally and this leads to a number of model refinements and a required calibration step. Finally, the overall performance of the method is assessed through a number of experiments in which the aberration state of the lithographic system is intentionally detuned and subsequently estimated by the new method. These experiments show a remarkably good agreement, with an error smaller than 5  mλ, among the requested aberrations, the aberrations measured by the on-tool aberration sensor, and the results of the new wafer-based method.

  5. Quantitative MR thermometry based on phase-drift correction PRF shift method at 0.35 T.

    Science.gov (United States)

    Chen, Yuping; Ge, Mengke; Ali, Rizwan; Jiang, Hejun; Huang, Xiaoyan; Qiu, Bensheng

    2018-04-10

    Noninvasive magnetic resonance thermometry (MRT) at low-field using proton resonance frequency shift (PRFS) is a promising technique for monitoring ablation temperature, since low-field MR scanners with open-configuration are more suitable for interventional procedures than closed systems. In this study, phase-drift correction PRFS with first-order polynomial fitting method was proposed to investigate the feasibility and accuracy of quantitative MR thermography during hyperthermia procedures in a 0.35 T open MR scanner. Unheated phantom and ex vivo porcine liver experiments were performed to evaluate the optimal polynomial order for phase-drift correction PRFS. The temperature estimation approach was tested in brain temperature experiments of three healthy volunteers at room temperature, and in ex vivo porcine liver microwave ablation experiments. The output power of the microwave generator was set at 40 W for 330 s. In the unheated experiments, the temperature root mean square error (RMSE) in the inner region of interest was calculated to assess the best-fitting order for polynomial fit. For ablation experiments, relative temperature difference profile measured by the phase-drift correction PRFS was compared with the temperature changes recorded by fiber optic temperature probe around the microwave ablation antenna within the target thermal region. The phase-drift correction PRFS using first-order polynomial fitting could achieve the smallest temperature RMSE in unheated phantom, ex vivo porcine liver and in vivo human brain experiments. In the ex vivo porcine liver microwave ablation procedure, the temperature error between MRT and fiber optic probe of all but six temperature points were less than 2 °C. Overall, the RMSE of all temperature points was 1.49 °C. Both in vivo and ex vivo experiments showed that MR thermometry based on the phase-drift correction PRFS with first-order polynomial fitting could be applied to monitor temperature changes during

  6. Selective pharmacological blockade of the 5-HT7 receptor attenuates light and 8-OH-DPAT induced phase shifts of mouse circadian wheel running activity

    Directory of Open Access Journals (Sweden)

    Jonathan eShelton

    2015-01-01

    Full Text Available Recent reports have illustrated a reciprocal relationship between circadian rhythm disruption and mood disorders. The 5-HT7 receptor may provide a crucial link between the two sides of this equation since the receptor plays a critical role in sleep, depression, and circadian rhythm regulation. To further define the role of the 5-HT7 receptor as a potential pharmacotherapy to correct circadian rhythm disruptions, the current study utilized the selective 5-HT7 antagonist JNJ-18038683 (10 mg/kg in three different circadian paradigms. While JNJ-18038683 was ineffective at phase shifting the onset of wheel running activity in mice when administered at different circadian time (CT points across the circadian cycle, pretreatment with JNJ-18038683 blocked non-photic phase advance (CT6 induced by the 5-HT1A/7 receptor agonist 8-OH-DPAT (3 mg/kg. Since light induced phase shifts in mammals are partially mediated via the modulation of the serotonergic system, we determined if JNJ-18038683 altered phase shifts induced by a light pulse at times known to phase delay (CT15 or advance (CT22 wheel running activity in free running mice. Light exposure resulted in a robust shift in the onset of activity in vehicle treated animals at both times tested. Administration of JNJ-18038683 significantly attenuated the light-induced phase delay and completely blocked the phase advance. The current study demonstrates that pharmacological blockade of the 5-HT7 receptor by JNJ-18038683 blunts both non-photic and photic phase shifts of circadian wheel running activity in mice. These findings highlight the importance of the 5-HT7 receptor in modulating circadian rhythms. Due to the opposite modulating effects of light resetting between diurnal and nocturnal species, pharmacotherapy targeting the 5-HT7 receptor in conjunction with bright light therapy may prove therapeutically beneficial by correcting the desynchronization of internal rhythms observed in depressed individuals.

  7. Combined passive acoustic mapping and magnetic resonance thermometry for monitoring phase-shift nanoemulsion enhanced focused ultrasound therapy

    Science.gov (United States)

    Crake, Calum; Meral, F. Can; Burgess, Mark T.; Papademetriou, Iason T.; McDannold, Nathan J.; Porter, Tyrone M.

    2017-08-01

    Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure. Here, we employed phase-shift nanoemulsions (PSNE) embedded in tissue phantoms to promote cavitation and hence temperature rise induced by FUS. In addition, we incorporated passive acoustic mapping (PAM) alongside simultaneous MR thermometry in order to visualize both acoustic emissions and temperature rise, within the bore of a full scale clinical MRI scanner. Focal cavitation of PSNE could be resolved using PAM and resulted in accelerated heating and increased the maximum elevated temperature measured via MR thermometry compared to experiments without nanoemulsions. Over time, the simultaneously acquired acoustic and temperature maps show translation of the focus of activity towards the FUS transducer, and the magnitude of the increase in cavitation and focal shift both increased with nanoemulsion concentration. PAM results were well correlated with MRI thermometry and demonstrated greater sensitivity, with the ability to detect cavitation before enhanced heating was observed. The results suggest that PSNE could be beneficial for enhancement of thermal focused ultrasound therapies and that PAM could be a critical tool for monitoring this process.

  8. Combined passive acoustic mapping and magnetic resonance thermometry for monitoring phase-shift nanoemulsion enhanced focused ultrasound therapy.

    Science.gov (United States)

    Crake, Calum; Meral, F Can; Burgess, Mark T; Papademetriou, Iason T; McDannold, Nathan J; Porter, Tyrone M

    2017-07-13

    Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure. Here, we employed phase-shift nanoemulsions (PSNE) embedded in tissue phantoms to promote cavitation and hence temperature rise induced by FUS. In addition, we incorporated passive acoustic mapping (PAM) alongside simultaneous MR thermometry in order to visualize both acoustic emissions and temperature rise, within the bore of a full scale clinical MRI scanner. Focal cavitation of PSNE could be resolved using PAM and resulted in accelerated heating and increased the maximum elevated temperature measured via MR thermometry compared to experiments without nanoemulsions. Over time, the simultaneously acquired acoustic and temperature maps show translation of the focus of activity towards the FUS transducer, and the magnitude of the increase in cavitation and focal shift both increased with nanoemulsion concentration. PAM results were well correlated with MRI thermometry and demonstrated greater sensitivity, with the ability to detect cavitation before enhanced heating was observed. The results suggest that PSNE could be beneficial for enhancement of thermal focused ultrasound therapies and that PAM could be a critical tool for monitoring this process.

  9. Realization of practical attenuated phase-shift mask with high-transmission KrF excimer laser exposure

    Science.gov (United States)

    Toyama, Nobuhito; Miyashita, Hiroyuki; Morikawa, Yasutaka; Fujita, Hiroshi; Iwase, Kazuya; Mohri, Hiroshi; Hayashi, Naoya; Sano, Hisatake

    1999-12-01

    A 17% transmittance embedded attenuated phase shift mask (ESPM) has been prepared and evaluated in terms of its optical printability of 180 nm to 150 nm hole features at KrF excimer laser light. A 6% transmission ESPM has also been evaluated for comparison. Contact hole features on test reticles were written by a laser writer with the laser proximity correction (LPC). The following effects of the LPC were found: (1) The mask CD is controlled within plus or minus 20 nm from the target for both dense and isolated features. (2) The CD was shifted over -20 nm for isolated eatures. (3) An improvement in CD linearity was observed where the CD error was kept within 10 to 70 nm even when the feature size and pitch were varied. A similarity in the results by Aerial Image Measurement Software (AIMS) and the optical simulator was found especially for isolated features, and this allows us to use the optical simulator instead of AIMS for evaluating the optical properties of EPSMs in some cases. By the Log-slopes of the optical intensity profiles of 180 nm contact hole features, we found that the high transmission EPSM has better Log-slope especially for isolated features. This means that the manufacturability of 180 nm contact holes will be achieved by using the high transmission EPSM. By similar evaluation we found that good manufacturability of 150 nm contact holes will be more difficult to achieve even by using the high transmission EPSM. The variation of CD-focus curves was analyzed for isolated contact hole features using AIMS data. The high transmission EPSM improves the exposure latitude for 180 nm features even with only 20 nm 4x resizing and also for 150 nm features but cannot improve the focus latitude. The Mask Error Factor (MEF) is evaluated by using the optical simulation. It is found to range in 1.1 - 1.5.

  10. Study of ac loss in Bi-2223/Ag tape under the simultaneous action of ac transport current and ac magnetic field shifted in phase

    International Nuclear Information System (INIS)

    Vojenciak, M; Souc, J; Ceballos, J M; Goemoery, F; Klincok, B; Pardo, E; Grilli, F

    2006-01-01

    Investigation of ac loss under the simultaneous action of the transport ac current and the external ac magnetic field is of prime importance for the reliable prediction of dissipation in electric power devices such as motors/generators, transformers and transmission cables. An experimental rig allowing us to perform ac loss measurements in such conditions, on short (10 cm) tape samples of high-temperature superconductor Bi-2223/Ag, was designed and tested. Both the electromagnetic and thermal methods were incorporated, allowing us to combine the better sensitivity of the former and the higher reliability of the latter. Our main aim was to see how the ac loss depends on the phase shift between the transport current and the external magnetic field. Such a shift could have different values in various applications. While in a transformer winding, the maximum phase shift at full load will probably not exceed a few degrees, in a three phase transmission cable in tri-axial configuration it is around 120 0 . Therefore, we explored the whole range of phase shifts from 0 to 360 0 . Surprisingly, the maxima of dissipation did not coincide with zero shift as expected from qualitative considerations

  11. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function

    OpenAIRE

    Servin, Manuel; Padilla, Moises; Garnica, Guillermo

    2016-01-01

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength PSA (DW-PSA) is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesi...

  12. A Multi-Pulse Front-End Rectifier System with Electronic Phase-Shifting for Harmonic Mitigation in Motor Drive Applications

    DEFF Research Database (Denmark)

    Zare, Firuz; Davari, Pooya; Blaabjerg, Frede

    2016-01-01

    In this paper, an electronic phase-shifting strategy has been optimized for a multi-parallel configuration of line-commutated rectifiers with a common dc-bus voltage used in motor drive application. This feature makes the performance of the system independent of the load profile and maximizes its...... harmonic reduction ability. To further reduce the generated low order harmonics, a dc-link current modulation scheme and its phase shift values of multi-drive systems have been optimized. Analysis and simulations have been carried out to verify the proposed method....

  13. Atom-wave diffraction between the Raman-Nath and the Bragg regime: Effective Rabi frequency, losses, and phase shifts

    International Nuclear Information System (INIS)

    Mueller, Holger; Chiow Shengwey; Chu, Steven

    2008-01-01

    We present an analytic theory of the diffraction of (matter) waves by a lattice in the 'quasi-Bragg' regime, by which we mean the transition region between the long-interaction Bragg and 'channeling' regimes and the short-interaction Raman-Nath regime. The Schroedinger equation is solved by adiabatic expansion, using the conventional adiabatic approximation as a starting point, and reinserting the result into the Schroedinger equation to yield a second-order correction. Closed expressions for arbitrary pulse shapes and diffraction orders are obtained and the losses of the population to output states otherwise forbidden by the Bragg condition are derived. We consider the phase shift due to couplings of the desired output to these states that depends on the interaction strength and duration and show how these can be kept negligible by a choice of smooth (e.g., Gaussian) envelope functions even in situations that substantially violate the adiabaticity condition. We also give an efficient method for calculating the effective Rabi frequency (which is related to the eigenvalues of Mathieu functions) in the quasi-Bragg regime

  14. Accumulation of Phase-Shift Nanoemulsions to Enhance MR-Guided Ultrasound-Mediated Tumor Ablation In Vivo

    Directory of Open Access Journals (Sweden)

    Jonathan A. Kopechek

    2013-01-01

    Full Text Available Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU is being explored as a non-invasive technology to treat solid tumors. However, the clinical use of HIFU for tumor ablation applications is currently limited by the long treatment times required. Phase-shift nanoemulsions (PSNE, consisting of liquid perfluorocarbon droplets that can be vaporized into microbubbles, are being developed to accelerate HIFU-mediated heating. The purpose of this study was to examine accumulation of PSNE in intramuscular rabbit tumors in vivo. MR images were acquired before and after intravenous injection of gadolinium-containing PSNE. MR signal enhancement was observed in rabbit tumors up to six hours after injection, indicating that PSNE accumulated in the tumors. In addition, PSNE vaporization was detected in the tumor with B-mode ultrasound imaging, and MR thermometry measurements indicated that PSNE accelerated the rate of HIFU-mediated heating. These results suggest that PSNE could dramatically improve the efficiency and clinical feasibility of MRgHIFU.

  15. Design considerations in projection phase-shift moiré topography based on theoretical analysis of fringe formation.

    Science.gov (United States)

    Buytaert, Jan A N; Dirckx, Joris J J

    2007-07-01

    Moiré topography is a well-established optical technique to measure the shape of three-dimensional surfaces, based on the geometric interference between an optical grid and its image deformed by an object surface. The technique produces fringes that represent contours of equal height, and from the recordings of several phase-shifted topograms surface height coordinates can be calculated. To perform these calculations, it is assumed that object height variation is small in comparison with the measurement setup dimensions, and this approximation leads to systematic errors in measurement accuracy. We present the mathematical description of the fringe formation process in projection moiré topography, and on the basis of these equations we establish the relation between setup geometry and upper limits of the systematic measurement errors. We derive the equations that determine design specifications needed to reduce the effects of approximations to be below the measurement resolution of the setup. It is shown that setup geometry should be adapted to the gray-scale measurement resolution of the imaging system. We show that, using an iterative correction from one fringe order to the next, measurement accuracy can be maintained over the entire object depth.

  16. Multi-bit wavelength coding phase-shift-keying optical steganography based on amplified spontaneous emission noise

    Science.gov (United States)

    Wang, Cheng; Wang, Hongxiang; Ji, Yuefeng

    2018-01-01

    In this paper, a multi-bit wavelength coding phase-shift-keying (PSK) optical steganography method is proposed based on amplified spontaneous emission noise and wavelength selection switch. In this scheme, the assignment codes and the delay length differences provide a large two-dimensional key space. A 2-bit wavelength coding PSK system is simulated to show the efficiency of our proposed method. The simulated results demonstrate that the stealth signal after encoded and modulated is well-hidden in both time and spectral domains, under the public channel and noise existing in the system. Besides, even the principle of this scheme and the existence of stealth channel are known to the eavesdropper, the probability of recovering the stealth data is less than 0.02 if the key is unknown. Thus it can protect the security of stealth channel more effectively. Furthermore, the stealth channel will results in 0.48 dB power penalty to the public channel at 1 × 10-9 bit error rate, and the public channel will have no influence on the receiving of the stealth channel.

  17. Information-theoretic security proof of differential-phase-shift quantum key distribution protocol based on complementarity

    Science.gov (United States)

    Mizutani, Akihiro; Sasaki, Toshihiko; Kato, Go; Takeuchi, Yuki; Tamaki, Kiyoshi

    2018-01-01

    We prove the information-theoretic security of the differential-phase-shift (DPS) quantum key distribution (QKD) protocol in the asymptotic regime based on the complementarity approach (arXiv:0704.3661 (2007)). Our security proof provides a slightly better key generation rate compared to the one derived in the previous security proof in (arXiv:1208.1995 (2012)) that is based on the Shor-Preskill approach (Shor and Preskill 2000 Phys. Rev. Lett. 85 441). This improvement is obtained because the complementarity approach can employ more detailed information on Alice’s sending state in estimating the leaked information to an eavesdropper. Moreover, we remove the necessity of the numerical calculation that was needed in the previous analysis to estimate the leaked information. This leads to an advantage that our security proof enables us to evaluate the security of the DPS protocol with any block size. This paper highlights one of the fundamental differences between the Shor-Preskill and the complementarity approaches.

  18. Covariant spectator theory of $np$ scattering:\\\\ Phase shifts obtained from precision fits to data below 350 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Franz Gross; Alfred Stadler

    2008-02-11

    Using the covariant spectator theory (CST), we present two one boson exchange kernels that have been successfully adjusted to fit the 2007 world $np$ data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a chi2/N = 1.06. The other model (designated WJC-2) has only 15 parameters and fits with a chi2/N = 1.12. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire data base, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 data base is presented.

  19. Phase advancing human circadian rhythms with morning bright light, afternoon melatonin, and gradually shifted sleep: can we reduce morning bright-light duration?

    Science.gov (United States)

    Crowley, Stephanie J; Eastman, Charmane I

    2015-02-01

    Efficient treatments to phase-advance human circadian rhythms are needed to attenuate circadian misalignment and the associated negative health outcomes that accompany early-morning shift work, early school start times, jet lag, and delayed sleep phase disorder. This study compared three morning bright-light exposure patterns from a single light box (to mimic home treatment) in combination with afternoon melatonin. Fifty adults (27 males) aged 25.9 ± 5.1 years participated. Sleep/dark was advanced 1 h/day for three treatment days. Participants took 0.5 mg of melatonin 5 h before the baseline bedtime on treatment day 1, and an hour earlier each treatment day. They were exposed to one of three bright-light (~5000 lux) patterns upon waking each morning: four 30-min exposures separated by 30 min of room light (2-h group), four 15-min exposures separated by 45 min of room light (1-h group), and one 30-min exposure (0.5-h group). Dim-light melatonin onsets (DLMOs) before and after treatment determined the phase advance. Compared to the 2-h group (phase shift = 2.4 ± 0.8 h), smaller phase-advance shifts were seen in the 1-h (1.7 ± 0.7 h) and 0.5-h (1.8 ± 0.8 h) groups. The 2-h pattern produced the largest phase advance; however, the single 30-min bright-light exposure was as effective as 1 h of bright light spread over 3.25 h, and it produced 75% of the phase shift observed with 2 h of bright light. A 30-min morning bright-light exposure with afternoon melatonin is an efficient treatment to phase-advance human circadian rhythms. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Phase advancing human circadian rhythms with morning bright light, afternoon melatonin, and gradually shifted sleep: can we reduce morning bright light duration?

    Science.gov (United States)

    Crowley, Stephanie J.; Eastman, Charmane I.

    2015-01-01

    OBJECTIVE Efficient treatments to phase advance human circadian rhythms are needed to attenuate circadian misalignment and the associated negative health outcomes that accompany early morning shift work, early school start times, jet lag, and delayed sleep phase disorder. This study compared three morning bright light exposure patterns from a single light box (to mimic home treatment) in combination with afternoon melatonin. METHODS Fifty adults (27 males) aged 25.9±5.1 years participated. Sleep/dark was advanced 1 hour/day for 3 treatment days. Participants took 0.5 mg melatonin 5 hours before baseline bedtime on treatment day 1, and an hour earlier each treatment day. They were exposed to one of three bright light (~5000 lux) patterns upon waking each morning: four 30-minute exposures separated by 30 minutes of room light (2 h group); four 15-minute exposures separated by 45 minutes of room light (1 h group), and one 30-minute exposure (0.5 h group). Dim light melatonin onsets (DLMOs) before and after treatment determined the phase advance. RESULTS Compared to the 2 h group (phase shift=2.4±0.8 h), smaller phase advance shifts were seen in the 1 h (1.7±0.7 h) and 0.5 h (1.8±0.8 h) groups. The 2-hour pattern produced the largest phase advance; however, the single 30-minute bright light exposure was as effective as 1 hour of bright light spread over 3.25 h, and produced 75% of the phase shift observed with 2 hours of bright light. CONCLUSIONS A 30-minute morning bright light exposure with afternoon melatonin is an efficient treatment to phase advance human circadian rhythms. PMID:25620199

  1. Cumulative-Phase-Alteration of Galactic-Light Passing Through the Cosmic-Microwave-Background: A New Mechanism for Some Observed Spectral-Shifts

    Directory of Open Access Journals (Sweden)

    Tank H. K.

    2012-07-01

    Full Text Available Currently, whole of the measured “cosmological-red-shift ” is interpreted as due to the “metric-expansion-of-space”; so for the required “closer -density” of the universe, we need twenty times more mass-energy than the visible baryonic-matter contained in the universe. This paper proposes a new mechanism, which can account for good per- centage of the red-shift in the extra-galactic-light, greatly reducing the requirement of dark matter-energy. Also, this mechanism can cause a new kin d of blue-shift reported here, and their observational evidences. These spectral-s hifts are proposed to result due to cumulative phase-alteration of extra-galactic-light b ecause of vector-addition of: (i electric-field of extra-galactic-light and (ii that of the cosmic-microwave-background (CMB. Since the center-frequency of CMB is much lower than extra-galactic-light, the cumulative-phase-alteration results in red -shift, observed as an additional contribu- tor to the measured “cosmological red-shift”; and since the center-frequency of CMB is higher than the radio-frequency-signals used to measure velocity of space-probes like: Pioneer-10, Pioneer-11, Galileo and Ulysses, the cum ulative-phase-alteration re- sulted in blue-shift, leading to the interpretation of deceleration of these space-probes. While the galactic-light experiences the red-shift, and th e ranging-signals of the space- probes experience blue -shift, they are comparable in magnitude, providing a supportive- evidence for the new mechanism proposed here. More confirmative-experiments for this new mechanism are also proposed.

  2. A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

    Directory of Open Access Journals (Sweden)

    Wenzheng Xu

    2017-10-01

    Full Text Available Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS and Zero Voltage Switching (ZVS in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.

  3. 80-Gb/s wavelength conversion based on cross-phase modulation in high-nonlinearity dispersion-shifted fiber and optical filtering

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle

    2001-01-01

    Using cross-phase modulation in a 1-km high-nonlinearity dispersion-shifted fiber with subsequent filtering by a tunable optical filter, 80-Gb/s pulsewidth maintained wavelength conversion is realized. Penalty-free transmission over 80-km conventional single-mode fiber and 12-km dispersion...

  4. Electrostatic ion-cyclotron waves in a nonuniform magnetic field

    International Nuclear Information System (INIS)

    Cartier, S.L.; D'Angelo, N.; Merlino, R.L.

    1985-01-01

    The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f> or approx. =f/sub c/i, where f/sub c/i is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism

  5. Dynamic measurements in non-uniform flows

    Science.gov (United States)

    Ershov, A. P.

    2017-12-01

    The response of gauges registering the flow velocity and pressure in highly non-uniform media (for example, a powder under shock compression or powdered low-density explosive) is simulated. The modeling employs an acoustic approach. Against the average level of the signal, the fluctuations generated by the heterogeneity of the medium are observed which may distort the results completely. For reliable measurements, gauges larger than the characteristic scale of the medium non-uniformity are required. Under this condition, electromagnetic flow measurements and the velocity interferometer system for any reflector (VISAR) produce quite similar flow velocity profiles with small level of noise.

  6. Cavitation-enhanced MR-guided focused ultrasound ablation of rabbit tumors in vivo using phase shift nanoemulsions

    Science.gov (United States)

    Kopechek, Jonathan A.; Park, Eun-Joo; Zhang, Yong-Zhi; Vykhodtseva, Natalia I.; McDannold, Nathan J.; Porter, Tyrone M.

    2014-07-01

    Advanced tumors are often inoperable due to their size and proximity to critical vascular structures. High intensity focused ultrasound (HIFU) has been developed to non-invasively thermally ablate inoperable solid tumors. However, the clinical feasibility of HIFU ablation therapy has been limited by the long treatment times (on the order of hours) and high acoustic intensities required. Studies have shown that inertial cavitation can enhance HIFU-mediated heating by generating broadband acoustic emissions that increase tissue absorption and accelerate HIFU-induced heating. Unfortunately, initiating inertial cavitation in tumors requires high intensities and can be unpredictable. To address this need, phase-shift nanoemulsions (PSNE) have been developed. PSNE consist of lipid-coated liquid perfluorocarbon droplets that are less than 200 nm in diameter, thereby allowing passive accumulation in tumors through leaky tumor vasculature. PSNE can be vaporized into microbubbles in tumors in order to nucleate cavitation activity and enhance HIFU-mediated heating. In this study, MR-guided HIFU treatments were performed on intramuscular rabbit VX2 tumors in vivo to assess the effect of vaporized PSNE on acoustic cavitation and HIFU-mediated heating. HIFU pulses were delivered for 30 s using a 1.5 MHz, MR-compatible transducer, and cavitation emissions were recorded with a 650 kHz ring hydrophone while temperature was monitored using MR thermometry. Cavitation emissions were significantly higher (P W of acoustic power was 46 ± 22% with PSNE injection. The results indicate that PSNE nucleates cavitation which correlates with enhanced HIFU-mediated heating in tumors. This suggests that PSNE could potentially be used to reduce the time and/or acoustic intensity required for HIFU-mediated heating, thereby increasing the feasibility and clinical efficacy of HIFU thermal ablation therapy.

  7. Image phase shift invariance based cloud motion displacement vector calculation method for ultra-short-term solar PV power forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fei; Zhen, Zhao; Liu, Chun; Mi, Zengqiang; Hodge, Bri-Mathias; Shafie-khah, Miadreza; Catalão, João P. S.

    2018-02-01

    Irradiance received on the earth's surface is the main factor that affects the output power of solar PV plants, and is chiefly determined by the cloud distribution seen in a ground-based sky image at the corresponding moment in time. It is the foundation for those linear extrapolation-based ultra-short-term solar PV power forecasting approaches to obtain the cloud distribution in future sky images from the accurate calculation of cloud motion displacement vectors (CMDVs) by using historical sky images. Theoretically, the CMDV can be obtained from the coordinate of the peak pulse calculated from a Fourier phase correlation theory (FPCT) method through the frequency domain information of sky images. The peak pulse is significant and unique only when the cloud deformation between two consecutive sky images is slight enough, which is likely possible for a very short time interval (such as 1?min or shorter) with common changes in the speed of cloud. Sometimes, there will be more than one pulse with similar values when the deformation of the clouds between two consecutive sky images is comparatively obvious under fast changing cloud speeds. This would probably lead to significant errors if the CMDVs were still only obtained from the single coordinate of the peak value pulse. However, the deformation estimation of clouds between two images and its influence on FPCT-based CMDV calculations are terrifically complex and difficult because the motion of clouds is complicated to describe and model. Therefore, to improve the accuracy and reliability under these circumstances in a simple manner, an image-phase-shift-invariance (IPSI) based CMDV calculation method using FPCT is proposed for minute time scale solar power forecasting. First, multiple different CMDVs are calculated from the corresponding consecutive images pairs obtained through different synchronous rotation angles compared to the original images by using the FPCT method. Second, the final CMDV is generated

  8. The importance of channel non-uniformity in riverine ecosystems

    Science.gov (United States)

    Pasternack, G. B.

    2007-12-01

    A key aspect of the hierarchical controls on riverine ecosystems that has been undervalued in both river science and restoration is the role of channel non-uniformity. As the water depth to bed grain size ratio decreases, channel non-uniformity takes over as a dominant control on hydraulic, geomorphic, and ecologic processes in rivers. As a case in point, the degree of channel degradation and habitat loss that ensues after dams are built may be directly related to maintenance of channel non-uniformity. The study reported here evaluated channel change at different spatial (submeter to km) and temporal (seasonal to interdecadal) scales in a regulated, but still dynamic, gravel-cobble river. The objectives were to (1) determine the cause of the persistence of riffles and pools even as the channel incised more than 10 m over 70 years and (2) evaluate the linkage between channel change and anadromous fish habitat in such a dynamic setting. The study area was the top 10.5 km of the Yuba River below Englebright Dam. Although this dam has blocked bedload transport into the reach for 65 years causing significant channel incision, a residual of 17.7 million m3 of sediment remains in the study reach due to historical hydraulic mining for gold. The approach used was to combine the knowledge gained at multiple scales using different methods, including historical aerial photo analysis, channel DEM analysis and differencing, 2D hydrodynamic modeling, hydraulic geometry analysis, fish observations, process-based hydrogeomorphic monitoring, and sediment transport experiments. These diverse methods revealed an array of mechanisms contributing to channel change and habitat rejuvenation, most notable including flow-convergence routing responsible for maintaining riffles and pools over a range of flows. Anadromous fish were observed to shift their pattern of habitat utilization in response to channel change in predictable ways. The primary lesson for river management is that more

  9. Stone Stability in Non-uniform Flow

    NARCIS (Netherlands)

    Hoan, N.T.; Stive, M.J.F.; Booij, R.; Hofland, B.; Verhagen, H.J.

    2011-01-01

    This paper presents the results of an experimental study on stone stability under nonuniform turbulent flow, in particular expanding flow. Detailed measurements of both flow and turbulence and the bed stability are described. Than various manners of quantifying the hydraulic loads exerted on the

  10. Stone Stability under Stationary Nonuniform Flows

    NARCIS (Netherlands)

    Steenstra, Remco; Hofland, B.; Paarlberg, Andries; Smale, Alfons; Huthoff, Fredrik; Uijttewaal, W.S.J.

    2016-01-01

    A stability parameter for rock in bed protections under nonuniform stationary flow is derived. The influence of the mean flow velocity, turbulence, and mean acceleration of the flow are included explicitly in the parameter. The relatively new notion of explicitly incorporating the mean acceleration

  11. Radar Doppler Processing with Nonuniform Sampling.

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-01

    Conventional signal processing to estimate radar Doppler frequency often assumes uniform pulse/sample spacing. This is for the convenience of t he processing. More recent performance enhancements in processor capability allow optimally processing nonuniform pulse/sample spacing, thereby overcoming some of the baggage that attends uniform sampling, such as Doppler ambiguity and SNR losses due to sidelobe control measures.

  12. Non-uniform tube representation of proteins

    DEFF Research Database (Denmark)

    Hansen, Mikael Sonne

    might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X...

  13. SU-E-T-410: Fringe Stability and Phase Shift Measurements in a Michelson Interferometer for Optical Calorimetry

    International Nuclear Information System (INIS)

    Flores-Martinez, E; Malin, M; DeWerd, L

    2014-01-01

    Purpose: To identify the variables limiting the resolution of a Michelson interferometer used to measure phase shifts (PS) in water as part of a radiometric calorimeter. Methods: We investigated the output stability of a He-Ne laser and a laser diode. The short and long term stability of the fringe pattern in a Michelson interferometer was tested with different types of lasers, thermal insulation arrangements, damping systems and optical mounts to optimize system performance. PS were induced by electrically heating water in a 1 cm quartz cuvette located in one of the interferometer arms. The PS was calculated from fringe intensity changes and compared to a calculated PS using thermocouple-measured temperature changes in the water. Results: The intensity of the laser diode is more stable, but the gas laser’s profile is more suitable for fringe analysis and has better temporal coherence. The laser requires a warm-up time of 4 hours before its output is stabilized (SNR>95). The fringe’s stability strongly depends on the thermal insulation. When the interferometer is exposed to ambient temperature swings of 0.7 K, it is not possible to stabilize the fringe pattern. Enclosing the system in a 2.5 cm-thick Styrofoam box improves the SNR, but further insulation will be needed to increase the SNR above 50. High frequency noise is significantly reduced by damping the system.Inducing a temperature rise in water, starting at 299 K, the average temperature increase for a 2π PS is 0.29 ± 0.02 K and the proportionality constant is -21.1 ± 0.8 radians/K. This is 5.8% lower than the calculated value using the thermocouple. Conclusion: Interferometric PS measurements of temperature may provide an alternative to thermistors for water calorimetry. The resolution of the current prototype is limited by ambient temperature stability. Calculated and measured thermally-induced PS in water agreed to within 5.8%

  14. Experimental research on the influence of system parameters on the composition shift for zeotropic mixture (isobutane/pentane) in a system occurring phase change

    International Nuclear Information System (INIS)

    Bao, Junjiang; Zhao, Li

    2016-01-01

    Highlights: • The influence of system parameters on the composition shift for zeotropic mixture is studied. • Zeotropic mixture isobutane/pentane is selected as the working fluids. • Circulating composition and charge have the inverse proportion relationship. • The relationship between circulating composition and charge composition is linear. - Abstract: Zeotropic mixture can improve the performance of the thermodynamic cycle ascribed to the better temperature match during the heat transfer process with the characteristics of temperature glide during evaporation and condensing processes. Another characteristic of zeotropic mixture is composition shift. Composition shift means that the circulating composition and charge composition is different and is mainly caused by the two-phase hold-up and different solubility in lubricating oil. The existence of composition shift will affect the design and operation of thermodynamic system. The previous study gave little information about the influence of system parameters on the composition shift in a system occurring phase change. This paper mainly discuss the influence of system parameters on the composition shift for zeotropic mixture in a system occurring phase change as well as the validation of the linear relationship between the circulating composition and the charge composition and the inverse proportion relationship between the circulating composition and the charge mass found based on our previous theory study (Zhao and Bao, 2014). With isobutane and pentane as the research object, the impact of the key system parameters (hot water temperature, mass flow rate of hot water, feed pump frequency, cold water temperature and evaporator length) on composition shift are experimentally carried out. The results show that when the hot water temperature, mass flow rate of hot water and evaporator length increase and cold water temperature decreases, circulating composition will increase. For feed pump frequency, when

  15. Calculations of recombination rates for cold 4He atoms from atom-dimer phase shifts and determination of universal scaling functions

    International Nuclear Information System (INIS)

    Shepard, J. R.

    2007-01-01

    Three-body recombination rates for cold 4 He are calculated with a method which exploits the simple relationship between the imaginary part of the atom-dimer elastic scattering phase shift and the S-matrix for recombination. The elastic phase shifts are computed above breakup threshold by solving a three-body Faddeev equation in momentum space with inputs based on a variety of modern atom-atom potentials. Recombination coefficients for the HFD-B3-FCII potential agree very well with the only previously published results. Since the elastic scattering and recombination processes for 4 He are governed by 'Efimov physics', they depend on universal functions of a scaling variable. The computed recombination coefficients for potentials other than HFD-B3-FCII make it possible to determine these universal functions

  16. Instruction sequence based non-uniform complexity classes

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2013-01-01

    We present an approach to non-uniform complexity in which single-pass instruction sequences play a key part, and answer various questions that arise from this approach. We introduce several kinds of non-uniform complexity classes. One kind includes a counterpart of the well-known non-uniform

  17. Results from a model system of superconducting solenoids and phase shifting bridge for pulsed power studies for proposed tokamak EF coils

    International Nuclear Information System (INIS)

    Fuja, R.E.; Kustom, R.L.; Smith, R.P.

    1977-01-01

    A matched pair of superconducting solenoids and a phase-shifting bridge circuit has been constructed to study energy storage and transfer for application to tokamak EF coils. The intrinsically stable solenoids, each with 4 H self-inductance, incorporate sufficient cooling to allow charging at several hundred volts, corresponding to B approximately equal 1 T/sec. The three-phase inductor-convertor capacitive bridge network operating at up to 150 V rms transfers energy reversibly and at controllable rates from the storage coil to the load coil

  18. Nonuniform transformation field analysis of multiphase elasto viscoplastic materials: application to MOX fuels

    International Nuclear Information System (INIS)

    Roussette, S.

    2005-05-01

    The description of the overall behavior of nonlinear materials with nonlinear dissipative phases requires an infinity of internal variables. An approximate model involving only a finite number of internal variables, Nonuniform Transformation Field Analysis, is obtained by considering a decomposition of these variables on a finite set of nonuniform transformation fields, called plastic modes. The method is initially developed for incompressible elasto viscoplastic materials. Karhunen-Loeve expansion is proposed to optimize the plastic modes. Then the method is extended to porous elasto viscoplastic materials. Finally the transformation field analysis, developed by Dvorak, is applied to nuclear fuels MOX. This method enables to make sensitivity studies to determine the role of some microstructural parameters on the fuel behaviour. Moreover the adequacy of the nonuniform method for fuels MOX is shown, the final objective being to be able to apply the model to the MOX in 3D. (author)

  19. Vortices in nonuniform upper-hybrid field

    International Nuclear Information System (INIS)

    Davydova, T.A.; Vranjes, J.

    1992-01-01

    The equations describing the interaction of an upper-hybrid pump wave with small low-frequency density perturbations are discussed under assumption that the pump is spatially nonuniform. The conditions for the modulational instability are investigated. Instead of a dispersion relation, describing the growth of perturbations in the case of an uniform pump, in our case of nonuniform pump a differential equation is obtained and from its eigenvalues are found the instability criteria. Taking into account the slow-frequency self-interaction terms some localized solutions similar to dipole vortices are found, but described by analytic functions in all space. It is shown that their characteristic size and speed are determined by the pump intensity and its spatial structure. (au)

  20. Non-uniform tube representation of proteins

    DEFF Research Database (Denmark)

    Hansen, Mikael Sonne

    Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better capture the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....

  1. Simulations of beam emittance growth from the collectiverelaxation of space-charge nonuniformities

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Steven M.; Grote, David P.; Davidson, Ronald C.

    2004-05-01

    Beams injected into a linear focusing channel typically have some degree of space-charge nonuniformity. For unbunched beams with high space-charge intensity propagating in linear focusing channels, Debye screening of self-field interactions tends to make the transverse density profile flat. An injected particle distribution with a large systematic charge nonuniformity will generally be far from an equilibrium of the focusing channel and the initial condition will launch a broad spectrum of collective modes. These modes can phase-mix and experience nonlinear interactions which result in an effective relaxation to a more thermal-equilibrium-like distribution characterized by a uniform density profile. This relaxation transfers self-field energy from the initial space-charge nonuniformity to the local particle temperature, thereby increasing beam phase space area (emittance growth). Here they employ two-dimensional electrostatic particle in cell (PIC) simulations to investigate the effects of initial transverse space-charge nonuniformities on the equality of beams with high space-charge intensity propagating in a continuous focusing channel. Results are compared to theoretical bounds of emittance growth developed in previous studies. Consistent with earlier theory, it is found that a high degree of initial distribution nonuniformity can be tolerated with only modest emittance growth and that beam control can be maintained. The simulations also provide information on the rate of relaxation and characteristic levels of fluctuations in the relaxed states. This research suggests that a surprising degree of initial space-charge nonuniformity can be tolerated in practical intense beam experiments.

  2. Design of a fully-fiber multi-chord interferometer and a new phase-shift demodulation method for field-reversed configuration

    Science.gov (United States)

    Fang, Dongfan; Sun, Qizhi; Zhao, Xiaoming; Jia, Yuesong

    2014-05-01

    A 633 nm laser interferometer has been designed based on a novel concept, which, without the acousto-optic modulator or the demodulator circuit, adopts the fibers to connect all elements except photodetectors and oscilloscope in this system to make it more compact, portable, and efficient. The noteworthy feature is to mathematically compare the two divided interference signals, which have the same phase-shift caused by the electron density but possess the different initial phase and low angular frequencies. It is possible to read the plasma density directly on the oscilloscope by our original mathematic demodulation method without a camera. Based on the Abel inversion algorithm, the radial electron density profiles versus time can be obtained by using the multi-chord system. The designed measurable phase shift ranges from 0 to 2π rad corresponding to the maximum line integral of electron density less than 3.5 × 1017 cm-2, and the phase accuracy is about 0.017 rad corresponding to the line integral of electron density accuracy of 1 × 1015 cm-2. After the construction of eight-chord interferometer, it will provide the detailed time resolved information of the spatial distribution of the electron density in the field-reversed configuration (FRC) plasma target produced by the "Yingguang-1" programmed-discharge device, which is being constructed in the Key Laboratory of Pulsed Power, China Academy of Engineering Physics.

  3. Design of a fully-fiber multi-chord interferometer and a new phase-shift demodulation method for field-reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Dongfan, E-mail: fangdongfan1208@126.com; Sun, Qizhi; Zhao, Xiaoming; Jia, Yuesong [Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAEP, P. O. Box 919-108, Mianyang, Sichuan 621999 (China)

    2014-05-15

    A 633 nm laser interferometer has been designed based on a novel concept, which, without the acousto-optic modulator or the demodulator circuit, adopts the fibers to connect all elements except photodetectors and oscilloscope in this system to make it more compact, portable, and efficient. The noteworthy feature is to mathematically compare the two divided interference signals, which have the same phase-shift caused by the electron density but possess the different initial phase and low angular frequencies. It is possible to read the plasma density directly on the oscilloscope by our original mathematic demodulation method without a camera. Based on the Abel inversion algorithm, the radial electron density profiles versus time can be obtained by using the multi-chord system. The designed measurable phase shift ranges from 0 to 2π rad corresponding to the maximum line integral of electron density less than 3.5 × 10{sup 17} cm{sup −2}, and the phase accuracy is about 0.017 rad corresponding to the line integral of electron density accuracy of 1 × 10{sup 15} cm{sup −2}. After the construction of eight-chord interferometer, it will provide the detailed time resolved information of the spatial distribution of the electron density in the field-reversed configuration (FRC) plasma target produced by the “Yingguang-1” programmed-discharge device, which is being constructed in the Key Laboratory of Pulsed Power, China Academy of Engineering Physics.

  4. Tilt Angle and the Temperature Shifts Calculated as a Function of Concentration for the AC* Phase Transition in a Binary Mixture of Liquid Crystals

    Science.gov (United States)

    Yurtseven, H.; Kurt, M.

    We study here the tilt angle and the temperature shifts as a function of concentration for the AC* phase transition in a binary mixture, using our mean field model with the biquadratic P2θ2 coupling — and also with the bilinear Pθ and P2θ2 couplings. By expanding the free energy in terms of the tilt angle and polarization, the tilt angle and the temperature shift are evaluated by using the coefficients given in the free energy expansion. By employing a concentration-dependent coefficient, the tilt angle and the temperature shift are calculated as a function of concentration of 10.O.4 for the SmAC* transition in a binary mixture of C7 and 10.O.4. Our calculated values of the tilt angle and the temperature shifts decrease as the concentration of 10.O.4 increases, as confirmed experimentally for the AC* transition in this binary mixture. This indicates that our mean field models studied here are satisfactory to explain the observed behavior of the AC* transition of the binary mixture of C7 and 10.O.4.

  5. Amplitude reduction and phase shifts of melatonin, cortisol and other circadian rhythms after a gradual advance of sleep and light exposure in humans.

    Science.gov (United States)

    Dijk, Derk-Jan; Duffy, Jeanne F; Silva, Edward J; Shanahan, Theresa L; Boivin, Diane B; Czeisler, Charles A

    2012-01-01

    The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep-wake cycle has not been fully characterized. We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days) and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity 'room' light (∼90-150 lux) or moderate light supplemented with bright light (∼10,000 lux) for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h). Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17-94%) and after bright light by 52% (range 12-84%), as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness. Alterations in the timing of the sleep-wake cycle and associated bright or moderate light exposure can lead to changes in phase and reduction of circadian amplitude which are consistent across multiple variables but differ between individuals. These data have implications for our understanding of circadian organization and the negative health outcomes associated with shift-work, jet-lag and exposure to artificial light.

  6. Interpretation of UV radiometric measurements of spectrally non-uniform sources

    International Nuclear Information System (INIS)

    Murphy, P.J.; Gardner, D.G.

    1988-01-01

    Narrow bandpass UV radiometers are used in a variety of high-temperature measurement applications. Significant systematic errors, in the form of an apparent wavelength shift in the system response curve, may be introduced when interpreting data obtained from spectrally nonuniform sources. Theoretical calculations, using transmission curves from commercially available narrow bandpass filters, show that the apparent shift in the system spectral response is a function of temperature for a blackbody source. A brief comparison between the theoretical analysis and experimentaal data is presented

  7. A tuning method for nonuniform traveling-wave accelerating structures

    International Nuclear Information System (INIS)

    Gong Cunkui; Zheng Shuxin; Shao Jiahang; Jia Xiaoyu; Chen Huaibi

    2013-01-01

    The tuning method of uniform traveling-wave structures based on non-resonant perturbation field distribution measurement has been widely used in tuning both constant-impedance and constant-gradient structures. In this paper, the method of tuning nonuniform structures is proposed on the basis of the above theory. The internal reflection coefficient of each cell is obtained from analyzing the normalized voltage distribution. A numerical simulation of tuning process according to the coupled cavity chain theory has been done and the result shows each cell is in right phase advance after tuning. The method will be used in the tuning of a disk-loaded traveling-wave structure being developed at the Accelerator Laboratory, Tsinghua University. (authors)

  8. Vibration and Dynamic Response Control of Nonuniform Composite Rotating Blades

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available This paper addresses the free vibration, dynamic response, and the active control of composite rotating pretwisted blades modeled as nonuniform thin-walled beams, fixed at the hub at a setting angle, and incorporating piezoelectrically induced damping capabilities. In this sense, a distributed piezoelectric actuator system activated through the application of an out-of-phase electrical current is used to suppress the dynamic response of the rotating beam subjected to a Heaviside pulse. The blade model incorporates nonclassical effects such as transverse shear, secondary warping, and rotary inertias, and includes the centrifugal and Coriolis force fields. A velocity feedback control law relating the piezoelectrically induced bending moment at the beam tip with appropriately selected kinematical response quantities is used, and the beneficial effects of its implementation upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.

  9. Fabrication of π phase-shifted fiber Bragg grating and its application in narrow linewidth 1.5 μm Er-doped fiber lasers

    Science.gov (United States)

    Sun, Junjie; Wang, Zefeng; Wang, Meng; Xi, Xiaoming; Cao, Jianqiu; Gu, Xijia; Chen, Jinbao

    2018-01-01

    Using a π phase-shifted fiber Bragg grating (PSFBG) as narrow band filtering component is an important method for narrow linewidth fiber lasers, which have lots of applications in fiber sensors, optical communication, coherent detection and combination. In this paper, we design and fabricate two π PSFBGs by π phase-shifted phase mask. A narrow linewidth 1.5 μm Er-doped fiber ring laser employing one of the two π PSFBGs is set up, and the characteristics of the laser power and spectrum are investigated experimentally. A maximum laser power about 2.22 W at 1549.5 nm with linewidth ∼1 GHz is achieved, and the maximum slope efficiency is 35.8%. To the best of our knowledge, it is the highest power for GHz-level C-band fiber lasers. Further, high-efficient, high-power, single-longitudinal-mode fiber lasers could be achieved by optimizing the π PSFBG and the structure of the cavity.

  10. All-optical encryption/decryption for nonreturn-to-zero differential phase-shift keying signals using four-wave mixing in semiconductor optical amplifier

    Science.gov (United States)

    Yang, Xuelin; Zhou, Peng; Hu, Xiaonan; Hu, Weisheng

    2015-04-01

    By experiment we demonstrate an all-optical encryption/decryption scheme for nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signals at 10 Gbit/s using all-optical exclusive-OR (XOR) logic. The key bit stream is performed by a pseudorandom bit stream. The all-optical XOR logic is achieved by nondegenerate four-wave mixing (FWM) in a semiconductor optical amplifier (SOA), which allows high data rate operation and asymmetric optical powers of the two input bit streams. The gain dynamics and pattern effect associated with the SOA carrier lifetime are alleviated due to the constant envelope of the NRZ-DPSK signals.

  11. Phage exposure causes dynamic shifts in the expression states of specific phase-variable genes of Campylobacter jejuni

    DEFF Research Database (Denmark)

    Aidley, Jack; Holst Sørensen, Martine C.; Bayliss, Christopher D.

    2017-01-01

    Phase variation (PV) creates phenotypic heterogeneity at high frequencies and in a reversible manner. This phenomenon allows bacteria to adapt to a variety of different environments and selective pressures. In Campylobacter jejuni this reversible adaptive process is mediated by mutations in homop......Phase variation (PV) creates phenotypic heterogeneity at high frequencies and in a reversible manner. This phenomenon allows bacteria to adapt to a variety of different environments and selective pressures. In Campylobacter jejuni this reversible adaptive process is mediated by mutations...... in homopolymeric G/C tracts. Many C. jejuni-specific phages are dependent on phase-variable surface structures for successful infection. We previously identified the capsular polysaccharide (CPS) moiety, MeOPN-GalfNAc, as a receptor for phage F336 and showed that phase-variable expression of the transferase...... for this CPS modification, cj1421, and two other phase-variable CPS genes generated phage resistance in C. jejuni. Here we investigate the population dynamics of C. jejuni NCTC11168 when exposed to phage F336 in vitro using a newly described method - the 28-locus-CJ11168 PV analysis. Dynamic switching...

  12. Phage exposure causes dynamic shifts in the expression states of specific phase-variable genes of Campylobacter jejuni

    DEFF Research Database (Denmark)

    Aidley, Jack; Holst Sørensen, Martine C.; Bayliss, Christopher D.

    2017-01-01

    was observed in the ON/OFF states of three phase-variable CPS genes, cj1421, cj1422 and cj1426, during phage F336 exposure, with the dominant phage-resistant phasotype differing between cultures. Although loss of the phage receptor was predominately observed, several other PV events also led to phage...... resistance, a phenomenon that increases the chance of phage-resistant subpopulations being present in any growing culture. No other PV genes were affected and exposure to phage F336 resulted in a highly specific response, only selecting for phase variants of cj1421, cj1422 and cj1426. In summary, C. jejuni...

  13. The non-uniformity of fossil preservation.

    Science.gov (United States)

    Holland, Steven M

    2016-07-19

    The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades.This article is part of the themed issue 'Dating species divergences using rocks and clocks'. © 2016 The Author(s).

  14. Pulsing blue light through closed eyelids: effects on acute melatonin suppression and phase shifting of dim light melatonin onset

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2014-12-01

    Full Text Available Mariana G Figueiro, Barbara Plitnick, Mark S Rea Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA Abstract: Circadian rhythm disturbances parallel the increased prevalence of sleep disorders in older adults. Light therapies that specifically target regulation of the circadian system in principle could be used to treat sleep disorders in this population. Current recommendations for light treatment require the patients to sit in front of a bright light box for at least 1 hour daily, perhaps limiting their willingness to comply. Light applied through closed eyelids during sleep might not only be efficacious for changing circadian phase but also lead to better compliance because patients would receive light treatment while sleeping. Reported here are the results of two studies investigating the impact of a train of 480 nm (blue light pulses presented to the retina through closed eyelids on melatonin suppression (laboratory study and on delaying circadian phase (field study. Both studies employed a sleep mask that provided narrowband blue light pulses of 2-second duration every 30 seconds from arrays of light-emitting diodes. The results of the laboratory study demonstrated that the blue light pulses significantly suppressed melatonin by an amount similar to that previously shown in the same protocol at half the frequency (ie, one 2-second pulse every minute for 1 hour. The results of the field study demonstrated that blue light pulses given early in the sleep episode significantly delayed circadian phase in older adults; these results are the first to demonstrate the efficacy and practicality of light treatment by a sleep mask aimed at adjusting circadian phase in a home setting. Keywords: circadian phase, dim light melatonin onset, light through closed eyelids, blue light, sleep

  15. Long term variability of the annual hydrological regime and sensitivity to temperature phase shifts in Saxony/Germany

    Directory of Open Access Journals (Sweden)

    M. Renner

    2011-06-01

    Full Text Available Recently, climatological studies report observational evidence of changes in the timing of the seasons, such as earlier timing of the annual cycle of surface temperature, earlier snow melt and earlier onset of the phenological spring season. Also hydrological studies report earlier timing and changes in monthly streamflows. From a water resources management perspective, there is a need to quantitatively describe the variability in the timing of hydrological regimes and to understand how climatic changes control the seasonal water budget of river basins.

    Here, the timing of hydrological regimes from 1930–2009 was investigated in a network of 27 river gauges in Saxony/Germany through a timing measure derived by harmonic function approximation of annual periods of runoff ratio series. The timing measure proofed to be robust and equally applicable to both mainly pluvial river basins and snow melt dominated regimes.

    We found that the timing of runoff ratio is highly variable, but markedly coherent across the basins analysed. Differences in average timing are largely explained by basin elevation. Also the magnitude of low frequent changes in the seasonal timing of streamflow and the sensitivity to the changes in the timing of temperature increase with basin elevation. This sensitivity is in turn related to snow storage and release, whereby snow cover dynamics in late winter explain a large part of the low- and high-frequency variability.

    A trend analysis based on cumulative anomalies revealed a common structural break around the year 1988. While the timing of temperature shifted earlier by 4 days, accompanied by a temperature increase of 1 K, the timing of runoff ratio within higher basins shifted towards occurring earlier about 1 to 3 weeks. This accelerated and distinct change indicates, that impacts of climate change on the water cycle may be strongest in higher, snow melt dominated basins.

  16. A stability criterion for HNFDE with non-uniform delays

    International Nuclear Information System (INIS)

    Liu Xingwen; Zhong Shouming; Zhang Fengli

    2005-01-01

    Stability of functional differential equations (FDE) is an increasingly important problem in both science and engineering. Delays, whether uniform or non-uniform, play an important role in the dynamics of a system. Since non-uniform delay is more general and less focused than uniform delay, this paper concentrates on the stability of high-order neutral functional differential equations (HNFDE) with non-uniform delay, and proposes a sufficient condition for it. This result may be widely helpful, thanks to the frequent emergence of a HNFDE with non-uniform delay in various fields. Its effectiveness is illustrated by some examples

  17. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function.

    Science.gov (United States)

    Servin, Manuel; Padilla, Moises; Garnica, Guillermo

    2016-05-02

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength (DW) PSA is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesis herein presented may be used for interferometric contouring of discontinuous industrial objects. Also DW-PSA may be useful for DW shop-testing of deep free-form aspheres. As shown here, using the FTF-based synthesis one may easily find explicit DW-PSA formulae optimized for high signal-to-noise and high detuning robustness. To this date, no general synthesis and analysis for temporal DW-PSAs has been given; only ad hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae for their spectra, their signal-to-noise, their detuning and harmonic robustness has been given. Here for the first time a fully general procedure for designing DW-PSAs (or triple-wavelengths PSAs) with desire spectrum, signal-to-noise ratio and detuning robustness is given. We finally generalize DW-PSA to higher number of wavelength temporal PSAs.

  18. Application of the finite-element method and the eigenmode expansion method to investigate the periodic and spectral characteristic of discrete phase-shift fiber Bragg grating

    Science.gov (United States)

    He, Yue-Jing; Hung, Wei-Chih; Syu, Cheng-Jyun

    2017-12-01

    The finite-element method (FEM) and eigenmode expansion method (EEM) were adopted to analyze the guided modes and spectrum of phase-shift fiber Bragg grating at five phase-shift degrees (including zero, 1/4π, 1/2π, 3/4π, and π). In previous studies on optical fiber grating, conventional coupled-mode theory was crucial. This theory contains abstruse knowledge about physics and complex computational processes, and thus is challenging for users. Therefore, a numerical simulation method was coupled with a simple and rigorous design procedure to help beginners and users to overcome difficulty in entering the field; in addition, graphical simulation results were presented. To reduce the difference between the simulated context and the actual context, a perfectly matched layer and perfectly reflecting boundary were added to the FEM and the EEM. When the FEM was used for grid cutting, the object meshing method and the boundary meshing method proposed in this study were used to effectively enhance computational accuracy and substantially reduce the time required for simulation. In summary, users can use the simulation results in this study to easily and rapidly design an optical fiber communication system and optical sensors with spectral characteristics.

  19. The effect of brain hematoma location on volumetric inductive phase shift spectroscopy of the brain with circular and magnetron sensor coils: a numerical simulation study

    International Nuclear Information System (INIS)

    Rojas, R; González, C A; Rubinsky, B

    2008-01-01

    This numerical simulation study addressed the effects of the location of a discrete brain hematoma on the volumetric inductive phase shift of the brain measured with an induction circular sensor coil and an induction magnetron sensor coil. The theoretical study simulates the brain cavity as a circular sphere transversely centered with respect to the circular and magnetron sensor coils. As a case study for the effects of hematoma location, we employed similar size simulated spherical hematomas placed at three different positions from the center of the brain outward. A three-dimensional finite element analysis of the field equations in the frequency range from 100 kHz to 100 MHz revealed a substantial effect of hematoma location on the ability of both the circular and magnetron sensors to detect the hematomas. In particular it was found that there are frequencies, which may be related to resonance, at which the occurrence of the hematomas has no effect on the volumetric inductive phase shift of the brain. Furthermore it was found that the relative sensitivity of circular and magnetron sensor coils with respect to the occurrence of hematoma varies with the location of the hematoma

  20. The threshold behaviour of scattering phase shifts in singular potentials; Das Schwellenverhalten von Streuphasen in singulaeren Potentialen

    Energy Technology Data Exchange (ETDEWEB)

    Arnecke, Florian

    2009-01-19

    In this thesis we have studied the threshold behaviour od scattering phases in attactive, singular potentials proportional to -1/r{sup {alpha}}, {alpha}>2, in two and three dimensions. Total absorption on the surface was described by incoming boundary condition in form of WKB waves, so that the scattering phase {delta}(k) is because of the particle loss a complex quantity and the S matrix no longer unitary. As application example we use the scattering behaviour of ultracold atoms on an absorbing sphere. The parameters were so chosen that they correspond to those of metastable helium (2{sup 3}S) atoms respectively sodium atoms in the ground state and a radius of the sphere of 200 respectively 2000 a. u. The final chapter presents a survey about the scattering on a circularly symmetric potential in two dimensions.

  1. A reconfigurable microwave photonic filter with flexible tunability using a multi-wavelength laser and a multi-channel phase-shifted fiber Bragg grating

    Science.gov (United States)

    Shi, Nuannuan; Hao, Tengfei; Li, Wei; Zhu, Ninghua; Li, Ming

    2018-01-01

    We propose a photonic scheme to realize a reconfigurable microwave photonic filter (MPF) with flexible tunability using a multi-wavelength laser (MWL) and a multi-channel phase-shifted fiber Bragg grating (PS-FBG). The proposed MPF is capable of performing reconfigurability including single bandpass filter, two independently bandpass filter and a flat-top bandpass filter. The performance such as the central frequency and the bandwidth of passband is tuned by controlling the wavelengths of the MWL. In the MPF, The light waves from a MWL are sent to a phase modulator (PM) to generate the phase-modulated optical signals. By applying a multi-channel PS-FBG, which has a series of narrow notches in the reflection spectrum with the free spectral range (FSR) of 0.8 nm, the +1st sidebands are removed in the notches and the phased-modulated signals are converted to the intensity-modulated signals without beating signals generation between each two optical carriers. The proposed MPF is also experimentally verified. The 3-dB bandwidth of the MPF is broadened from 35 MHz to 135 MHz and the magnitude deviation of the top from the MPF is less than 0.2 dB within the frequency tunable range from 1 GHz to 5 GHz.

  2. Impact of frequency modulation ratio on capacitor cells balancing in phase-shifted PWM based chain-link STATCOM

    DEFF Research Database (Denmark)

    Behrouzian, Ehsan; Bongiorno, Massimo; Teodorescu, Remus

    2014-01-01

    that any deviation from the ideal conditions lead to undesired harmonics, which will impact the charge of the dc capacitors. It is also shown that for low switching frequencies, cells voltage sideband harmonics interact with baseband harmonics of the current and causes extra source of unbalance. In order...... distribution among cells of the same phase leg, thus contributing to the capacitors balancing. Theoretical conclusions are validated through PSCAD simulation results....

  3. Analysis of the origins of content non-uniformity in high-shear wet granulation.

    Science.gov (United States)

    Oka, Sarang; Smrčka, David; Kataria, Anjali; Emady, Heather; Muzzio, Fernando; Štěpánek, František; Ramachandran, Rohit

    2017-08-07

    In this study, the origins of granule content non-uniformity in the high-shear wet granulation of a model two-component pharmaceutical blend were investigated. Using acetaminophen as the active pharmaceutical ingredient (API) and microcrystalline cellulose as the excipient, the distribution of the API across the granule size classes was measured for a range of conditions that differed in the duration of the initial dry mixing stage, the overall composition of the blend and the wet massing time. The coarse granule fractions were found to be systematically sub-potent, while the fines were enriched in the API. The extent of content non-uniformity was found to be dependent on two factors - powder segregation during dry mixing and redistribution of the API between the granule size fractions during the wet massing phase. The latter was demonstrated in an experiment where the excipient was pre-granulated, the API was added later and wet massed. The content non-uniformity in this case was comparable to that obtained when both components were present in the granulator from the beginning. With increasing wet massing time, the extent of content non-uniformity decreased, indicating that longer wet massing times might be a solution for systems with a natural tendency for component segregation. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans

    Science.gov (United States)

    Dijk, Derk-Jan; Duffy, Jeanne F.; Silva, Edward J.; Shanahan, Theresa L.; Boivin, Diane B.; Czeisler, Charles A.

    2012-01-01

    Background The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep-wake cycle has not been fully characterized. Methodology/Principal Findings We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days) and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity ‘room’ light (∼90–150 lux) or moderate light supplemented with bright light (∼10,000 lux) for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h). Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17–94%) and after bright light by 52% (range 12–84%), as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness. Conclusions/Significance Alterations in the timing of the sleep-wake cycle and associated bright or moderate light exposure can lead to changes in phase and reduction of circadian amplitude which are consistent across multiple variables but differ between individuals. These data have implications for our understanding of circadian organization and the negative health outcomes associated with shift-work, jet

  5. Amplitude reduction and phase shifts of melatonin, cortisol and other circadian rhythms after a gradual advance of sleep and light exposure in humans.

    Directory of Open Access Journals (Sweden)

    Derk-Jan Dijk

    Full Text Available BACKGROUND: The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep-wake cycle has not been fully characterized. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity 'room' light (∼90-150 lux or moderate light supplemented with bright light (∼10,000 lux for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h. Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54% (17-94% and after bright light by 52% (range 12-84%, as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness. CONCLUSIONS/SIGNIFICANCE: Alterations in the timing of the sleep-wake cycle and associated bright or moderate light exposure can lead to changes in phase and reduction of circadian amplitude which are consistent across multiple variables but differ between individuals. These data have implications for our understanding of circadian organization and the negative health outcomes associated with shift

  6. A train of blue light pulses delivered through closed eyelids suppresses melatonin and phase shifts the human circadian system

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2013-10-01

    Full Text Available Mariana G Figueiro, Andrew Bierman, Mark S ReaLighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USAAbstract: A model of circadian phototransduction was published in 2005 to predict the spectral sensitivity of the human circadian system to narrow-band and polychromatic light sources by combining responses to light from the spectral-opponent “blue” versus “yellow” cone bipolar pathway with direct responses to light by the intrinsically photosensitive retinal ganglion cells. In the model, depolarizing “blue” responses, but not hyperpolarizing “yellow” responses, from the “blue” versus “yellow” pathway are combined with the intrinsically photosensitive retinal ganglion cell responses. Intrinsically photosensitive retinal ganglion cell neurons are known to be much slower to respond to light than the cone pathway, so an implication of the model is that periodic flashes of “blue” light, but not “yellow” light, would be effective for stimulating the circadian system. A within-subjects study was designed to test the implications of the model regarding retinal exposures to brief flashes of light. The study was also aimed at broadening the foundation for clinical treatment of circadian sleep disorders by delivering flashing light through closed eyelids while people were asleep. In addition to a dark control night, the eyelids of 16 subjects were exposed to three light-stimulus conditions in the phase delay portion of the phase response curve while they were asleep: (1 2-second flashes of 111 W/m2 of blue (λmax ≈ 480 nm light once every minute for 1 hour, (2 131 W/m2 of green (λmax ≈ 527 nm light, continuously on for 1 hour, and (3 2-second flashes of the same green light once every minute for 1 hour. Inferential statistics showed that the blue flash light-stimulus condition significantly delayed circadian phase and significantly suppressed nocturnal melatonin. The results of this study further our

  7. Study of the Micro-Nonuniformity of the Plastic Deformation of Steel

    Science.gov (United States)

    Chechulin, B. B.

    1957-01-01

    The plastic flow during deformation of real polycrystalline metals has specific characteristics which distinguish the plastic deformation of metals from the deformation of ordinary isotropic bodies. One of these characteristics is the marked micro-nonuniformity of the plastic deformation of metals. P.O. Pashkov demonstrated the presence of a considerable micro-nonuniformity of the plastic deformation of coarse-grained steel wit medium or low carbon content. Analogous results in the case of tension of coarse-grained aluminum were obtained by W. Boas, who paid particular attention to the role of the grain boundaries in plastic flow. The nonuniformit of the plastic deformation in microvolumes was also recorded by T.N. Gudkova and others, on the alloy KhN80T. N.F. Lashko pointed out the nonuniformity of the plastic deformation for a series of pure polycrystalline metals and one-phase alloys. In his later reports, P.O. Pashkov arrives at he conclusion that the nonuniformity of the distribution of the deformation along the individual grains has a significant effect on the strength and plastic characteristics of polycrystalline metals in the process of plastic flow. However, until now there has not existed any systematic investigation of the general rules of the microscopic nonuniformit of plastic deformation even though the real polycrystalline metals are extremely simple with regard to structure. In the present report, an attempt is made to study the micrononuniformity of the flow of polycrystalline metals by the method of statistical analysis of the variation of the frequency diagrams of the nonuniformity of the grains in the process of plastic deformation.

  8. Analysis for reflection peaks of multiple-phase-shift based sampled fiber Bragg gratings and application in high channel-count filter design.

    Science.gov (United States)

    Wen, Kun Hua; Yan, Lian Shan; Pan, Wei; Luo, Bin; Zou, Xi Hua; Ye, Jia; Ma, Ya Nan

    2009-10-10

    An analytical expression for calculating the reflection-peak wavelengths (RPWs) of a uniform sampled fiber Bragg grating (SFBG) with the multiple-phase-shift (MPS) technique is derived through Fourier transform of the index modulation. The new expression can accurately depict the RPWs incorporating various parameters such as the duty cycle and the DC index change. The effectiveness of the derived expression is further confirmed by comparing the RPWs estimated from the expression with the simulated reflective spectra using the piecewise uniform method. And the reflective spectrum has been well optimized by introducing the Gaussian apodization function to suppress the sidelobes without any wavelength shift on the RPWs. Then, a high-channel-count comb filter based on MPS is proposed by cascading two or more SFBGs with different Bragg periods but with the same RPWs. Noticeably, the RPWs of the new structured SFBG can also be accurately calculated through the expression. Furthermore, the number of spectral channels can be controlled by choosing gratings with specified difference Bragg periods.

  9. Mössbauer study of local environment effects in the ordered Fe 70Al 30 Invar alloy: Temperature dependence of isomer shift in the spin-glass phase

    Science.gov (United States)

    Delyagin, N. N.; Erzinkyan, A. L.; Parfenova, V. P.; Rozantsev, I. N.

    2011-12-01

    The systematic studies of the magnetic hyperfine field distribution for 57Fe in the spin-glass (SG) phase of the ordered Fe70Al30 Invar alloy have been performed using Mössbauer spectroscopy technique in the temperature range from 5 to 80 K. Particular emphasis has been placed on the low-field component of the distribution, which is considered as corresponding to the Fe sites in the SG magnetic configurations. The main result is the observation of the pronounced temperature dependence of isomer shift for several atomic SG configurations. The temperature behavior of the local electron density is strongly correlated to the Invar properties of the Fe70Al30 alloy. We argue that the observed temperature dependence of the isomer shift due to a local volume effect. The temperature range, for which the pronounced decrease in atomic volume is observed, coincides with the range of the existence of the Invar effect. The influence of the competition between opposite in sign exchange interactions on the Invar properties is discussed.

  10. An in-building network based on community access television integration with quadrature phase-shift keying orthogonal frequency-division multiplexing

    International Nuclear Information System (INIS)

    Chen, Chia-Yi; Lin, Ying-Pyng; Lu, Hai-Han; Wu, Po-Yi; Lin, Huang-Chang; Wu, Hsiao-Wen

    2012-01-01

    An in-building network based on cable television (CATV) integration with quadrature phase-shift keying (QPSK) orthogonal frequency-division multiplexing (OFDM) transport over a combination of single-mode fibers (SMF) and perfluorinated graded-index plastic optical fibers (GI-POF) is proposed and experimentally demonstrated. In this system, a 1558.5 nm optical signal is directly transmitted along two fiber spans (20 km SMF + 25 m GI-POF). An optimum guard band is carefully established to ensure that no very substantial signal interference is induced between the CATV and QPSK OFDM bands. Error free transmission with sufficiently low bit error rate values was achieved for 1.25 Gbps/771.5 MHz QPSK OFDM signals; also, acceptable carrier-to-noise ratio, composite second-order, and composite triple-beat performances were obtained for CATV signals. This proposed network is significant because it is economical and convenient to install. (paper)

  11. The single-particle density of states, bound states, phase-shift flip, and a resonance in the presence of an Aharonov-Bohm potential

    International Nuclear Information System (INIS)

    Moroz, A.

    1994-01-01

    Both the nonrelativistic scattering and the spectrum in the presence of the Aharonov-Bohm potential are analyzed, and the single-particle density of states for different self-adjoint extensions is calculated, which is shown to be a symmetric and periodic function of the flux depending only on the distance from the nearest integer. The Aharonov-Casher theorem on the number of zero modes is corrected for the singular field configuration. The Hall resistivity is calculated in the dilute vortex limit. The magnetic moment coupling and not the spin is shown to be the primary source for the phase-shift flip that may occur even in its absence. The total energy of the system consisting of particles and field is discussed. (author) 65 refs.; 5 figs.; 1 tab

  12. (n,d) elastic differential cross section at 2.48 and 3.28 MeV and related phase shift analyses

    International Nuclear Information System (INIS)

    Chatelain, P.; Onel, Y.; Viennet, R.; Weber, J.

    1978-01-01

    In the case of (n,d) scattering, at energies of a few MeV, the elastic differential scattering cross sections are not well determined, especially beyond costhetasub(CM) = -0.8 and the number of data points is rather scarce. This lack of experimental data causes great difficulty to perform a phase shift analysis even in the simple case when partial waves up to lsub(max) = 2 are included as free parameters in the parametrization of the scattering amplitude. We have therefore, in the framework of our study of the (n,d) scattering, measured this cross section at 2.48 and 3.28 MeV with special emphasize on large scattering angles. (orig./WL) [de

  13. An NPC/H-bridge modular photovoltaic grid connected inverter with new-phase shifted PWM technique

    Energy Technology Data Exchange (ETDEWEB)

    Wanjekeche, T.; Nicolae, D.V.; Jimoh, A.A. [Tshwane Univ. of Technology, Pretoria (South Africa). Dept. of Electrical Engineering

    2010-08-13

    The commonly used topologies for converting direct current power generated by solar panels to high quality alternating current power at the interface to the grid are the high- frequency and line frequency voltage source grid interface system. These topologies utilize transformers which come with negative features such as increase in cost, size and weight of the whole inverter. In addition, the efficiency and reliability of the system is reduced. A novel option for inverters is the multilevel concept as it is based on low frequency switching and provides voltage or current of low sharing between the power semiconductors. The key topologies which have been suggested for multilevel converters are diode clamped or neutral point clamped (NPC); capacitor clamped of flying capacitors (FC); and cascaded H-bridge inverters with separate direct current sources. The cascaded H-bridge converter demonstrates superior qualities among the multilevel converter topologies as a result of its modularity and flexibility. This paper investigated the operating principle of a cascaded NPC/H-bridge inverter for photovoltaic-grid application. The superior characteristics of the model were analyzed using the state space techniques and double Fourier principle. A new and improved phase sifted PWM technique was proposed and its performance was compared. The main system configuration, mathematical modeling, and simulation model were presented. The state space equation showed that the model has 8 different operating modes which can be utilized to realize 5 level voltages per cell. 13 refs., 1 tab., 6 figs.

  14. Shifts in the fluorescence lifetime of EGFP during bacterial phagocytosis measured by phase-sensitive flow cytometry

    Science.gov (United States)

    Li, Wenyan; Houston, Kevin D.; Houston, Jessica P.

    2017-01-01

    Phase-sensitive flow cytometry (PSFC) is a technique in which fluorescence excited state decay times are measured as fluorescently labeled cells rapidly transit a finely focused, frequency-modulated laser beam. With PSFC the fluorescence lifetime is taken as a cytometric parameter to differentiate intracellular events that are challenging to distinguish with standard flow cytometry. For example PSFC can report changes in protein conformation, expression, interactions, and movement, as well as differences in intracellular microenvironments. This contribution focuses on the latter case by taking PSFC measurements of macrophage cells when inoculated with enhanced green fluorescent protein (EGFP)-expressing E. coli. During progressive internalization of EGFP-E. coli, fluorescence lifetimes were acquired and compared to control groups. It was hypothesized that fluorescence lifetimes would correlate well with phagocytosis because phagosomes become acidified and the average fluorescence lifetime of EGFP is known to be affected by pH. We confirmed that average EGFP lifetimes consistently decreased (3 to 2 ns) with inoculation time. The broad significance of this work is the demonstration of how high-throughput fluorescence lifetime measurements correlate well to changes that are not easily tracked by intensity-only cytometry, which is affected by heterogeneous protein expression, cell-to-cell differences in phagosome formation, and number of bacterium engulfed.

  15. New high statistics measurement of Ke4 decay form factors and ππ scattering phase shifts TH1"-->

    Science.gov (United States)

    Batley, J. R.; Culling, A. J.; Kalmus, G.; Lazzeroni, C.; Munday, D. J.; Slater, M. W.; Wotton, S. A.; Arcidiacono, R.; Bocquet, G.; Cabibbo, N.; Ceccucci, A.; Cundy, D.; Falaleev, V.; Fidecaro, M.; Gatignon, L.; Gonidec, A.; Kubischta, W.; Norton, A.; Maier, A.; Patel, M.; Peters, A.; Balev, S.; Frabetti, P. L.; Goudzovski, E.; Hristov, P.; Kekelidze, V.; Kozhuharov, V.; Litov, L.; Madigozhin, D.; Marinova, E.; Molokanova, N.; Polenkevich, I.; Potrebenikov, Y.; Stoynev, S.; Zinchenko, A.; Monnier, E.; Swallow, E.; Winston, R.; Rubin, P.; Walker, A.; Baldini, W.; Cotta Ramusino, A.; Dalpiaz, P.; Damiani, C.; Fiorini, M.; Gianoli, A.; Martini, M.; Petrucci, F.; Savrié, M.; Scarpa, M.; Wahl, H.; Bizzeti, A.; Calvetti, M.; Celeghini, E.; Iacopini, E.; Lenti, M.; Martelli, F.; Ruggiero, G.; Veltri, M.; Behler, M.; Eppard, K.; Kleinknecht, K.; Marouelli, P.; Masetti, L.; Moosbrugger, U.; Morales Morales, C.; Renk, B.; Wache, M.; Wanke, R.; Winhart, A.; Coward, D.; Dabrowski, A.; Fonseca Martin, T.; Shieh, M.; Szleper, M.; Velasco, M.; Wood, M. D.; Anzivino, G.; Cenci, P.; Imbergamo, E.; Nappi, A.; Pepe, M.; Petrucci, M. C.; Piccini, M.; Raggi, M.; Valdata-Nappi, M.; Cerri, C.; Collazuol, G.; Costantini, F.; Dilella, L.; Doble, N.; Fantechi, R.; Fiorini, L.; Giudici, S.; Lamanna, G.; Mannelli, I.; Michetti, A.; Pierazzini, G.; Sozzi, M.; Bloch-Devaux, B.; Cheshkov, C.; Chèze, J. B.; de Beer, M.; Derré, J.; Marel, G.; Mazzucato, E.; Peyaud, B.; Vallage, B.; Holder, M.; Ziolkowski, M.; Bifani, S.; Biino, C.; Cartiglia, N.; Clemencic, M.; Goy Lopez, S.; Marchetto, F.; Dibon, H.; Jeitler, M.; Markytan, M.; Mikulec, I.; Neuhofer, G.; Widhalm, L.

    2008-04-01

    We report results from a new measurement of the Ke4 decay K±→π+π-e±ν by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670 000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F,G,H) and ππ phase difference (δ=δs-δp) have been measured in ten independent bins of the ππ mass spectrum to investigate their variation. A sizeable acceptance at large ππ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the ππ scattering lengths a0 0 and a0 2. Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (a0 0,a0 2): a0 0=0.233±0.016stat±0.007syst,a0 2=-0.0471±0.011stat±0.004syst. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory.

  16. Comparing Time-Of and Phase-Shift the Survey of the Royal Pantheon in the Basilica of San Isidoro (LEÓN)

    Science.gov (United States)

    San José Alonso, J. I.; Martínez Rubio, J.; Fernández Martín, J. J.; García Fernández, J.

    2011-09-01

    The appearance of the Terrestrial Laser Scanners or 3D Scanners in Heritage recording has been relatively recent and it is submitted to a constant evolution determined mainly by the big technological advance in fields like Optics, Signal Processing, Electronics and Computer Science. As they have become popular so suddenly, it is essential to study the behavior of these evolving devices in a variety of scenarios to support an accurate assessment of their capabilities. Until two years ago, TOF (time-of-flight) and PS (phase-shift) technologies could hardly be considered side by side comparable, at least under equal terms and requirements. The first enables much longer ranges, while the latter dominated the short distances producing more accurate data with very high acquisition rates. Today, in a sort of convergent career, the scope of phase-shift technology has grown to near 200 meters and the time-of-flight team have been increasing their speed to figures as 100,000 points per second. In this article we expose the results of the comparison between the data delivered by two scanners based on the two related technologies that categorize today's both long and medium-range scanners. The two have been opposed face to face in the survey of the so called "the Sistine Chapel of the Spanish Romanesque" during the same day, and under the same environmental conditions, using equivalent capture settings. But now that as we noted these technologies can fight in the same arena, can we claim to be able to produce similar results whatever which one we choose? The answer is "no" or a "conditioned yes" at least. Let's leave numbers and nominal specifications behind and see what else makes them behave so differently.

  17. COMPARING TIME-OF-FLIGHT AND PHASE-SHIFT. THE SURVEY OF THE ROYAL PANTHEON IN THE BASILICA OF SAN ISIDORO (LEÓN

    Directory of Open Access Journals (Sweden)

    J. I. San José Alonso

    2012-09-01

    Full Text Available The appearance of the Terrestrial Laser Scanners or 3D Scanners in Heritage recording has been relatively recent and it is submitted to a constant evolution determined mainly by the big technological advance in fields like Optics, Signal Processing, Electronics and Computer Science. As they have become popular so suddenly, it is essential to study the behavior of these evolving devices in a variety of scenarios to support an accurate assessment of their capabilities. Until two years ago, TOF (time-of-flight and PS (phase-shift technologies could hardly be considered side by side comparable, at least under equal terms and requirements. The first enables much longer ranges, while the latter dominated the short distances producing more accurate data with very high acquisition rates. Today, in a sort of convergent career, the scope of phase-shift technology has grown to near 200 meters and the time-of-flight team have been increasing their speed to figures as 100,000 points per second. In this article we expose the results of the comparison between the data delivered by two scanners based on the two related technologies that categorize today's both long and medium-range scanners. The two have been opposed face to face in the survey of the so called "the Sistine Chapel of the Spanish Romanesque" during the same day, and under the same environmental conditions, using equivalent capture settings. But now that as we noted these technologies can fight in the same arena, can we claim to be able to produce similar results whatever which one we choose? The answer is "no" or a "conditioned yes" at least. Let’s leave numbers and nominal specifications behind and see what else makes them behave so differently.

  18. Direct deposition of gas phase generated aerosol gold nanoparticles into biological fluids--corona formation and particle size shifts.

    Directory of Open Access Journals (Sweden)

    Christian R Svensson

    Full Text Available An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity to a large extent may determine the nanoparticle effects and possible translocation to other organs.

  19. Direct Deposition of Gas Phase Generated Aerosol Gold Nanoparticles into Biological Fluids - Corona Formation and Particle Size Shifts

    Science.gov (United States)

    Svensson, Christian R.; Messing, Maria E.; Lundqvist, Martin; Schollin, Alexander; Deppert, Knut; Pagels, Joakim H.; Rissler, Jenny; Cedervall, Tommy

    2013-01-01

    An ongoing discussion whether traditional toxicological methods are sufficient to evaluate the risks associated with nanoparticle inhalation has led to the emergence of Air-Liquid interface toxicology. As a step in this process, this study explores the evolution of particle characteristics as they move from the airborne state into physiological solution. Airborne gold nanoparticles (AuNP) are generated using an evaporation-condensation technique. Spherical and agglomerate AuNPs are deposited into physiological solutions of increasing biological complexity. The AuNP size is characterized in air as mobility diameter and in liquid as hydrodynamic diameter. AuNP:Protein aggregation in physiological solutions is determined using dynamic light scattering, particle tracking analysis, and UV absorption spectroscopy. AuNPs deposited into homocysteine buffer form large gold-aggregates. Spherical AuNPs deposited in solutions of albumin were trapped at the Air-Liquid interface but was readily suspended in the solutions with a size close to that of the airborne particles, indicating that AuNP:Protein complex formation is promoted. Deposition into serum and lung fluid resulted in larger complexes, reflecting the formation of a more complex protein corona. UV absorption spectroscopy indicated no further aggregation of the AuNPs after deposition in solution. The corona of the deposited AuNPs shows differences compared to AuNPs generated in suspension. Deposition of AuNPs from the aerosol phase into biological fluids offers a method to study the protein corona formed, upon inhalation and deposition in the lungs in a more realistic way compared to particle liquid suspensions. This is important since the protein corona together with key particle properties (e.g. size, shape and surface reactivity) to a large extent may determine the nanoparticle effects and possible translocation to other organs. PMID:24086363

  20. Genetic shifts in methicillin-resistant Staphylococcus aureus epidemic clones and toxin gene profiles in Japan: comparative analysis among pre-epidemic, epidemic and post-epidemic phases.

    Science.gov (United States)

    Osaka, Shunsuke; Okuzumi, Katsuko; Koide, Shota; Tamai, Kiyoko; Sato, Tomoaki; Tanimoto, Koichi; Tomita, Haruyoshi; Suzuki, Masahiro; Nagano, Yukiko; Shibayama, Keigo; Arakawa, Yoshichika; Nagano, Noriyuki

    2018-03-01

    The decline in methicillin-resistant Staphylococcus aureus (MRSA) isolation rates has become a general observation worldwide, including Japan. We hypothesized that some genetic shift in MRSA might cause this phenomenon, and therefore we investigated the genetic profiles among MRSA clinical isolates obtained from three different epidemic phases in Japan. A total of 353 MRSA isolates were selected from 202 medical facilities in 1990 (pre-epidemic phase), 2004 (epidemic phase) and 2016 (post-epidemic phase). Molecular typing was performed by PCR detection of 22 genes using the polymerase chain reaction (PCR)-based ORF typing (POT) system, including an additional eight genes including small genomic islets and seven toxin genes. Isolates with a POT1 of score 93, identified as presumed clonal complex (pCC)5-staphylococcal cassette chromosome mec (SCCmec) type II including ST5-SCCmec type II New York/Japan clone, represented the major epidemic MRSA lineage in 1990 and 2004. In 2016, however, a marked decrease in isolates with a POT1 score of 93, along with changes in the epidemiology of toxin genes carried, was noted, where the carriers of tst genes including the tst-sec combination were markedly reduced, and those possessing the seb gene alone were markedly increased. Rather, isolates with a POT1 score of 106, including pCC1 or pCC8 among the isolates with SCCmec type IV, which often links to community-associated MRSA, were predominant. Interestingly, the pCC1 and pCC8 lineages were related to sea and tst-sec carriage, respectively. Over time, a transition in MRSA genetic profiles from a POT1 score of 93 in 1990 and 2004 to 106 in 2014 was found in Japan.

  1. Effects of astigmatism on spectra and polarization of aberrant electromagnetic nonuniformly correlated beams in turbulent ocean.

    Science.gov (United States)

    Tang, Miaomiao; Zhao, Daomu

    2014-12-01

    Analytical formulas are derived, for the cross spectral density matrix of electromagnetic nonuniformly correlated (EMUNC) beams, with astigmatic aberration propagating through oceanic turbulence. We investigate the effects of astigmatism on the spectral density, and the spectral degree of polarization, in great detail. It can be seen that, unlike for an aberration-free case, the lateral shifted intensity maximum (of an astigmatic EMUNC beam) does not return back to the on-axis position, after propagating at sufficiently large distances in the turbulence. Furthermore, in the far-zone, the deviation of its maximum value (from the optical axis) gradually increases, in accordance with growing propagation distance.

  2. Bridge density functional approximation for non-uniform hard core repulsive Yukawa fluid

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2008-01-01

    In this work, a bridge density functional approximation (BDFA) (J. Chem. Phys. 112, 8079 (2000)) for a non-uniform hard-sphere fluid is extended to a non-uniform hard-core repulsive Yukawa (HCRY) fluid. It is found that the choice of a bulk bridge functional approximation is crucial for both a uniform HCRY fluid and a non-uniform HCRY fluid. A new bridge functional approximation is proposed, which can accurately predict the radial distribution function of the bulk HCRY fluid. With the new bridge functional approximation and its associated bulk second order direct correlation function as input, the BDFA can be used to well calculate the density profile of the HCRY fluid subjected to the influence of varying external fields, and the theoretical predictions are in good agreement with the corresponding simulation data. The calculated results indicate that the present BDFA captures quantitatively the phenomena such as the coexistence of solid-like high density phase and low density gas phase, and the adsorption properties of the HCRY fluid, which qualitatively differ from those of the fluids combining both hard-core repulsion and an attractive tail. (condensed matter: structure, thermal and mechanical properties)

  3. Flexural Free Vibrations of Multistep Nonuniform Beams

    Directory of Open Access Journals (Sweden)

    Guojin Tan

    2016-01-01

    Full Text Available This paper presents an exact approach to investigate the flexural free vibrations of multistep nonuniform beams. Firstly, one-step beam with moment of inertia and mass per unit length varying as I(x=α11+βxr+4 and m(x=α21+βxr was studied. By using appropriate transformations, the differential equation for flexural free vibration of one-step beam with variable cross section is reduced to a four-order differential equation with constant coefficients. According to different types of roots for the characteristic equation of four-order differential equation with constant coefficients, two kinds of modal shape functions are obtained, and the general solutions for flexural free vibration of one-step beam with variable cross section are presented. An exact approach to solve the natural frequencies and modal shapes of multistep beam with variable cross section is presented by using transfer matrix method, the exact general solutions of one-step beam, and iterative method. Numerical examples reveal that the calculated frequencies and modal shapes are in good agreement with the finite element method (FEM, which demonstrates the solutions of present method are exact ones.

  4. Long GRBs sources population non-uniformity

    Science.gov (United States)

    Arkhangelskaja, Irene

    Long GRBs observed in the very wide energy band. It is possible to separate two subsets of GRBs with high energy component (E > 500 MeV) presence. First type events energy spectra in low and high energy intervals are similar (as for GRB 021008) and described by Band, power law or broken power law models look like to usual bursts without emission in tens MeV region. For example, Band spectrum of GRB080916C covering 6 orders of magnitude. Second ones contain new additional high energy spectral component (for example, GRB 050525B and GRB 090902B). Both types of GRBs observed since CGRO mission beginning. The low energy precursors existence are typical for all types bursts. Both types of bursts temporal profiles can be similar in the various energy regions during some events or different in other cases. The absence of hard to soft evolution in low energy band and (or) presence of high energy precursors for some events are the special features of second class of GRBs by the results of preliminary data analysis and this facts gives opportunities to suppose differences between these two GRBs subsets sources. Also the results of long GRB redshifts distribution analysis have shown its shape contradiction to uniform population objects one for our Metagalaxy to both total and various redshifts definition methods GRBs sources samples. These evidences allow making preliminary conclusion about non-uniformity of long GRBs sources population.

  5. Vortex convection in nonuniform compressible flow

    Science.gov (United States)

    Szumowski, A. P.; Meier, G. E. A.

    1988-03-01

    Vortex convection in longitudinally nonuniform transonic flow fields was studied. Vortices moving in moderately accelerated flow are distinct in the subsonic and supersonic range. Due to the acceleration, the vortices of the Karman street separate continuously one from another. They form a series of periodically shedding individual vortices. The density distribution of the accelerated vortices stays circular. Vortices in subsonic stream (behind the shock wave in the divergent part of the Laval nozzle) impinging on an obstacle (in this case on the regulating valve) cause shock fronts which move upstream. In a subsonic stream flowing out from the convergent nozzle, the primary vortices inside the stream significantly perturb its boundaries and induce secondary vortices (at the boundaries). Flow patterns in a duct with a sudden enlargement of cross section are influenced by the vortices convected in the flow too. However, the observed perturbations of these patterns are relatively weak. The unsteady behaviour of the free stream is not only the effect of the vortex convection but also of the unsteady interactions with the boundaries, i.e., the adjusting valve and the test-section walls. However, the effect of the vortex convection is the stronger.

  6. Minimum nonuniform graph partitioning with unrelated weights

    Science.gov (United States)

    Makarychev, K. S.; Makarychev, Yu S.

    2017-12-01

    We give a bi-criteria approximation algorithm for the Minimum Nonuniform Graph Partitioning problem, recently introduced by Krauthgamer, Naor, Schwartz and Talwar. In this problem, we are given a graph G=(V,E) and k numbers ρ_1,\\dots, ρ_k. The goal is to partition V into k disjoint sets (bins) P_1,\\dots, P_k satisfying \\vert P_i\\vert≤ ρi \\vert V\\vert for all i, so as to minimize the number of edges cut by the partition. Our bi-criteria algorithm gives an O(\\sqrt{log \\vert V\\vert log k}) approximation for the objective function in general graphs and an O(1) approximation in graphs excluding a fixed minor. The approximate solution satisfies the relaxed capacity constraints \\vert P_i\\vert ≤ (5+ \\varepsilon)ρi \\vert V\\vert. This algorithm is an improvement upon the O(log \\vert V\\vert)-approximation algorithm by Krauthgamer, Naor, Schwartz and Talwar. We extend our results to the case of 'unrelated weights' and to the case of 'unrelated d-dimensional weights'. A preliminary version of this work was presented at the 41st International Colloquium on Automata, Languages and Programming (ICALP 2014). Bibliography: 7 titles.

  7. Shifting Attention

    Science.gov (United States)

    Ingram, Jenni

    2014-01-01

    This article examines the shifts in attention and focus as one teacher introduces and explains an image that represents the processes involved in a numeric problem that his students have been working on. This paper takes a micro-analytic approach to examine how the focus of attention shifts through what the teacher and students do and say in the…

  8. Coronal heating by Alfven waves dissipation in compressible nonuniform media

    International Nuclear Information System (INIS)

    Malara, Francesco; Primavera, Leonardo; Veltri, Pierluigi

    1996-01-01

    The possibility to produce small scales and then to efficiently dissipate energy has been studied by Malara et al. [1992b] in the case of MHD disturbances propagating in an weakly dissipative incompressible and inhomogeneous medium, for a strictly 2D geometry. We extend this work to include both compressibility and the third component for vector quantities. Numerical simulations show that, when an Alfven wave propagates in a compressible nonuniform medium, the two dynamical effects responsible for the small scales formation in the incompressible case are still at work: energy pinching and phase-mixing. These effects give rise to the formation of compressible perturbations (fast and slow waves or a static entropy wave). Some of these compressive fluctuations are subject to the steepening of the wave front and become shock waves, which are extremely efficient in dissipating their energy, their dissipation being independent of the Reynolds number. Rough estimates of the typical times the various dynamical processes take to produce small scales show that these times are consistent with those required to dissipate inside the solar corona the energy of Alfven waves of photospheric origin

  9. Non-uniform sampling of NMR relaxation data

    DEFF Research Database (Denmark)

    Schwarz-Linnet, Troels; Teilum, Kaare

    2016-01-01

    The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors...... of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition...... in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of (15)N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance...

  10. Formation of vortex chains in a nonuniform magnetized electron plasma

    International Nuclear Information System (INIS)

    Shukla, P.K.; Srinivas, J.; Murtaza, G.; Saleem, H.

    1994-01-01

    It is shown that the equations governing the dynamics of weakly interacting medium-frequency electrostatic waves in a nonuniform magnetoplasma with a fixed ion background can have localized vortex chain solutions

  11. Pattern of diffusion-limited aggregation on nonuniform substrate

    CERN Document Server

    Ouyang Wen Ze; Zou Xian Wu; Jin Zhun Zhi

    2003-01-01

    Pattern of diffusion-limited aggregation (DLA) on nonuniform substrate was investigated by computer simulations. The nonuniform substrates are represented by Leath percolations with the probability p. p stands for the degree of nonuniformity and takes values in the range p sub c<=p<=1, where p sub c is the threshold of percolation. The DLA cluster grows up on the Leath percolation substrate. The patterns of the DLA clusters appear asymmetrical and nonuniform, and the branches are relative few for the case p is close to p sub c. In addition, the pattern depends on the shape of substrate. As p increases from p sub c to 1, cluster changes to pure DLA gradually. Correspondingly, the fractal dimension increases from 1.46 to 1.68. Also, the random walks on Leath percolations through the range p sub c<=p<=1 were examined. Our simulations show the Honda-Toyoki-Matsushita relation is still reasonable for fractional dimensional systems.

  12. Dielectrophoresis device and method having nonuniform arrays for manipulating particles

    Science.gov (United States)

    Cummings, Eric B.; Fintschenko, Yolanda; Simmons, Blake A.

    2012-09-04

    Microfluidic devices according to embodiments of the present invention include an inlet port, an outlet port, and a channel or chamber having a non-uniform array of insulating features on one or more surfaces. Electrodes are provided for generation of a spatially non-uniform electric field across the array. A voltage source, which may be an A.C. and/or a D.C. voltage source may be coupled to the electrodes for the generation of the electric field.

  13. The timing of the human circadian clock is accurately represented by the core body temperature rhythm following phase shifts to a three-cycle light stimulus near the critical zone

    Science.gov (United States)

    Jewett, M. E.; Duffy, J. F.; Czeisler, C. A.

    2000-01-01

    A double-stimulus experiment was conducted to evaluate the phase of the underlying circadian clock following light-induced phase shifts of the human circadian system. Circadian phase was assayed by constant routine from the rhythm in core body temperature before and after a three-cycle bright-light stimulus applied near the estimated minimum of the core body temperature rhythm. An identical, consecutive three-cycle light stimulus was then applied, and phase was reassessed. Phase shifts to these consecutive stimuli were no different from those obtained in a previous study following light stimuli applied under steady-state conditions over a range of circadian phases similar to those at which the consecutive stimuli were applied. These data suggest that circadian phase shifts of the core body temperature rhythm in response to a three-cycle stimulus occur within 24 h following the end of the 3-day light stimulus and that this poststimulus temperature rhythm accurately reflects the timing of the underlying circadian clock.

  14. Compensation for nonuniform attenuation in SPECT brain imaging

    International Nuclear Information System (INIS)

    Glick, S.J.; King, M.A.; Pan, T.S.; Soares, E.J.

    1996-01-01

    Accurate compensation for photon attenuation is needed to perform quantitative brain single-photon-emission computed tomographic (SPECT) imaging. Bellini's attenuation-compensation method has been used with a nonuniform attenuation map to account for the nonuniform attenuation properties of the head. Simulation studies using a three-dimensional (3-D) digitized anthropomorphic brain phantom were conducted to compare quantitative accuracy of reconstructions obtained with the nonuniform Bellini method to that obtained with the Chang method and to iterative reconstruction using maximum-likelihood expectation maximization (ML-EM). Using the Chang method and assuming the head to be a uniform attenuator gave reconstructions with an average bias of approximately 6-8%, whereas using the Bellini or the iterative ML-EM method with a nonuniform attenuation map gave an average bias of approximately 1%. The computation time required to implement nonuniform attenuation compensation with the Bellini algorithm is approximately equivalent to the time required to perform one iteration of ML-EM. Thus, using the Bellini method with a nonuniform attenuation map provides accurate compensation for photon attenuation within the head, and the method can be implemented in computation times suitable for routine clinical use

  15. cGMP-dependent protein kinase II modulates mPer1 and mPer2 gene induction and influences phase shifts of the circadian clock.

    Science.gov (United States)

    Oster, Henrik; Werner, Claudia; Magnone, Maria Chiara; Mayser, Helmut; Feil, Robert; Seeliger, Mathias W; Hofmann, Franz; Albrecht, Urs

    2003-04-29

    In mammals, the master circadian clock that drives many biochemical, physiological, and behavioral rhythms is located in the suprachiasmatic nuclei (SCN) of the hypothalamus. Generation and maintenance of circadian rhythmicity rely on complex interlocked transcriptional/translational feedback loops involving a set of clock genes. Among the molecular components driving the mammalian circadian clock are the Period 1 and 2 (mPer1 and mPer2) genes. Because the periodicity of the clock is not exactly 24 hr, it has to be adjusted periodically. The major stimulus for adjustment (resetting) of the clock is nocturnal light. It evokes activation of signaling pathways in the SCN that ultimately lead to expression of mPer1 and mPer2 genes conveying adjustment of the clock. We show that mice deficient in cGMP-dependent protein kinase II (cGKII, also known as PKGII), despite regular retinal function, are defective in resetting the circadian clock, as assessed by changes in the onset of wheel running activity after a light pulse. At the molecular level, light induction of mPer2 in the SCN is strongly reduced in the early period of the night, whereas mPer1 induction is elevated in cGKII-deficient mice. Additionally, we show that light induction of cfos and light-dependent phosphorylation of CREB at serine 133 are not affected in these animals. cGKII plays a role in the clock-resetting mechanism. In particular, the ability to delay clock phase is affected in cGKII-deficient mice. It seems that the signaling pathway involving cGKII influences in an opposite manner the light-induced induction of mPer1 and mPer2 genes and thereby influences the direction of a phase shift of the circadian clock.

  16. Abdominal aorta: characterisation of blood flow and measurement of its regional distribution by cine magnetic resonance phase-shift velocity mapping

    Energy Technology Data Exchange (ETDEWEB)

    Amanuma, M. [Dept. of Radiology, Saitama Medical School (Japan); Mohiaddin, R.H. [Magnetic Resonance Unit, Royal Brompton Hospital, London (United Kingdom); Hasegawa, M. [Dept. of Radiology, Saitama Medical School (Japan); Heshiki, A. [Dept. of Radiology, Saitama Medical School (Japan); Longmore, D.B. [Magnetic Resonance Unit, Royal Brompton Hospital, London (United Kingdom)

    1992-12-01

    Magnetic resonance phase-shift-induced velocity mapping is a powerful technique for measuring in vivo blood velocity and flow non-invasively. Using this method we examined dimensions, distensibility, blood flow and its regional distribution in the abdominal aorta in 10 normal volunteers. Data were acquired at three levels of the descending aorta. Thirty percent reduction in diastolic cross sectional area was observed in the caudal direction between these levels. Total blood flow (ml/min) in the abdominal aorta at the three sites was 4094{+-}1600, 2339{+-}910 and 1602{+-}549 respectively. Flows in the coeliac trunk, superior mesenteric artery and renal arteries were also calculated. The net flow in the abdominal aorta above the coeliac trunk was persistently forward, while there was considerable backflow (13% of total instantaneous flow) below the renal arteries during early diastole. Magnetic resonance imaging is a non-invasive technique for quantitative assessment of blood flow in the abdominal aorta and its main branches. (orig.)

  17. Intercomparison of a Cavity Attenuated Phase Shift-based extinction monitor (CAPS PMex with an integrating nephelometer and a filter-based absorption monitor

    Directory of Open Access Journals (Sweden)

    A. Petzold

    2013-05-01

    Full Text Available An evaluation of the Cavity Attenuated Phase Shift particle light extinction monitor (CAPS PMex using a combination of a 3-wavelength Integrating Nephelometer (NEPH and a 3-wavelength filter-based Particle Soot Absorption Photometer (PSAP was carried out using both laboratory-generated test particles and ambient aerosols. An accurate determination of a fixed pathlength correction for the CAPS PMex was made by comparing extinction measurements using monodisperse PSL spheres in combination with Mie scattering calculations to account for the presence of PSL conglomerates. These studies yielded a linear instrument response over the investigated dynamical range from 20 to 450 Mm−1 (10−6 m−1 with a linear correlation coefficient of R2 > 0.98. The adjustment factor was determined to be 1.05 times that previously reported. Correlating CAPS extinction to extinction measured by the NEPH + PSAP combination using laboratory-generated polydisperse mixtures of purely scattering ammonium sulfate and highly absorbing black carbon provided a linear regression line with slope m = 1.00 (R2 = 0.994 for single-scattering albedo values (λ = 630 nm ranging from 0.35 (black carbon to 1.00 (ammonium sulfate. For ambient aerosol, light extinction measured by CAPS was highly correlated (R2 = 0.995 to extinction measured by the NEPH + PSAP combination with slope m = 0.95.

  18. A Novel Choice Procedure of Magnetic Component Values for Phase Shifted Full Bridge Converters with a Variable Dead-Time Control Method

    Directory of Open Access Journals (Sweden)

    Lei Zhao

    2015-09-01

    Full Text Available Magnetic components are important parts of the phase shifted full bridge (PSFB converter. During the dead-time of switches located in the same leg, the converter can achieve zero-voltage-switching (ZVS by using the energies stored in magnetic components to discharge or charge the output capacitances of switches. Dead-time is usually calculated under a given set of pre-defined load condition which results in that the available energies are insufficient and ZVS capability is lost at light loads. In this paper, the PSFB converter is controlled by variable dead-time method and thus full advantage can be taken of the energies stored in magnetic components. Considering that dead-time has a great effect on ZVS, the relationship between available energies and magnetic component values is formulated by analyzing the equivalent circuits during dead-time intervals. Magnetic component values are chosen based on such relationship. The proposed choice procedure can make the available energies greater than the required energies for ZVS operation over a wide range of load conditions. Moreover, the burst mode control is adopted in order to reduce the standby power loss. Experimental results coincide with the theoretical analysis. The proposed method is a simple and practical solution to extend the ZVS range.

  19. Combination of a fast white-light interferometer with a phase shifting interferometric line sensor for form measurements of precision components

    Science.gov (United States)

    Laubach, Sören; Ehret, Gerd; Riebling, Jörg; Lehmann, Peter

    2017-06-01

    By means of an interferometric line sensor system, the form of a specimen can be measured by stitching several overlapping circular subapertures to form one 3D topography. This concept is very flexible and can be adapted to many different specimen geometries. The sensor is based on a Michelson interferometer configuration that consists of a rapidly oscillating reference mirror in combination with a high-speed line-scan camera. Due to the overlapping areas, movement errors of the scan axes can be corrected. In order to automatically adjust the line sensor in such a way that it is perpendicular to the measurement surface at a fixed working distance, a white-light interferometer was included in the line-based form-measuring system. By means of a fast white-light scan, the optimum angle of the sensor (with respect to the surface of the specimen) is determined in advance, before scanning the specimen using the line-based sinusoidal phase shifting interferometer. This produces accurate measurement results and makes it possible to also measure non-rotational specimens. In this paper, the setup of the line-based form-measuring system is introduced and the measurement strategy of the sensor adjustment using an additional white-light interferometer is presented. Furthermore, the traceability chain of the system and the main error influences are discussed. Examples of form measurement results are shown.

  20. Automated cell tracking and analysis in phase-contrast videos (iTrack4U: development of Java software based on combined mean-shift processes.

    Directory of Open Access Journals (Sweden)

    Fabrice P Cordelières

    Full Text Available Cell migration is a key biological process with a role in both physiological and pathological conditions. Locomotion of cells during embryonic development is essential for their correct positioning in the organism; immune cells have to migrate and circulate in response to injury. Failure of cells to migrate or an inappropriate acquisition of migratory capacities can result in severe defects such as altered pigmentation, skull and limb abnormalities during development, and defective wound repair, immunosuppression or tumor dissemination. The ability to accurately analyze and quantify cell migration is important for our understanding of development, homeostasis and disease. In vitro cell tracking experiments, using primary or established cell cultures, are often used to study migration as cells can quickly and easily be genetically or chemically manipulated. Images of the cells are acquired at regular time intervals over several hours using microscopes equipped with CCD camera. The locations (x,y,t of each cell on the recorded sequence of frames then need to be tracked. Manual computer-assisted tracking is the traditional method for analyzing the migratory behavior of cells. However, this processing is extremely tedious and time-consuming. Most existing tracking algorithms require experience in programming languages that are unfamiliar to most biologists. We therefore developed an automated cell tracking program, written in Java, which uses a mean-shift algorithm and ImageJ as a library. iTrack4U is a user-friendly software. Compared to manual tracking, it saves considerable amount of time to generate and analyze the variables characterizing cell migration, since they are automatically computed with iTrack4U. Another major interest of iTrack4U is the standardization and the lack of inter-experimenter differences. Finally, iTrack4U is adapted for phase contrast and fluorescent cells.

  1. Automated cell tracking and analysis in phase-contrast videos (iTrack4U): development of Java software based on combined mean-shift processes.

    Science.gov (United States)

    Cordelières, Fabrice P; Petit, Valérie; Kumasaka, Mayuko; Debeir, Olivier; Letort, Véronique; Gallagher, Stuart J; Larue, Lionel

    2013-01-01

    Cell migration is a key biological process with a role in both physiological and pathological conditions. Locomotion of cells during embryonic development is essential for their correct positioning in the organism; immune cells have to migrate and circulate in response to injury. Failure of cells to migrate or an inappropriate acquisition of migratory capacities can result in severe defects such as altered pigmentation, skull and limb abnormalities during development, and defective wound repair, immunosuppression or tumor dissemination. The ability to accurately analyze and quantify cell migration is important for our understanding of development, homeostasis and disease. In vitro cell tracking experiments, using primary or established cell cultures, are often used to study migration as cells can quickly and easily be genetically or chemically manipulated. Images of the cells are acquired at regular time intervals over several hours using microscopes equipped with CCD camera. The locations (x,y,t) of each cell on the recorded sequence of frames then need to be tracked. Manual computer-assisted tracking is the traditional method for analyzing the migratory behavior of cells. However, this processing is extremely tedious and time-consuming. Most existing tracking algorithms require experience in programming languages that are unfamiliar to most biologists. We therefore developed an automated cell tracking program, written in Java, which uses a mean-shift algorithm and ImageJ as a library. iTrack4U is a user-friendly software. Compared to manual tracking, it saves considerable amount of time to generate and analyze the variables characterizing cell migration, since they are automatically computed with iTrack4U. Another major interest of iTrack4U is the standardization and the lack of inter-experimenter differences. Finally, iTrack4U is adapted for phase contrast and fluorescent cells.

  2. Determining temperature distribution in tissue in the focal plane of the high (>100 W/cm(2)) intensity focused ultrasound beam using phase shift of ultrasound echoes.

    Science.gov (United States)

    Karwat, Piotr; Kujawska, Tamara; Lewin, Peter A; Secomski, Wojciech; Gambin, Barbara; Litniewski, Jerzy

    2016-02-01

    In therapeutic applications of High Intensity Focused Ultrasound (HIFU) the guidance of the HIFU beam and especially its focal plane is of crucial importance. This guidance is needed to appropriately target the focal plane and hence the whole focal volume inside the tumor tissue prior to thermo-ablative treatment and beginning of tissue necrosis. This is currently done using Magnetic Resonance Imaging that is relatively expensive. In this study an ultrasound method, which calculates the variations of speed of sound in the locally heated tissue volume by analyzing the phase shifts of echo-signals received by an ultrasound scanner from this very volume is presented. To improve spatial resolution of B-mode imaging and minimize the uncertainty of temperature estimation the acoustic signals were transmitted and received by 8 MHz linear phased array employing Synthetic Transmit Aperture (STA) technique. Initially, the validity of the algorithm developed was verified experimentally in a tissue-mimicking phantom heated from 20.6 to 48.6 °C. Subsequently, the method was tested using a pork loin sample heated locally by a 2 MHz pulsed HIFU beam with focal intensity ISATA of 129 W/cm(2). The temperature calibration of 2D maps of changes in the sound velocity induced by heating was performed by comparison of the algorithm-determined changes in the sound velocity with the temperatures measured by thermocouples located in the heated tissue volume. The method developed enabled ultrasound temperature imaging of the heated tissue volume from the very inception of heating with the contrast-to-noise ratio of 3.5-12 dB in the temperature range 21-56 °C. Concurrently performed, conventional B-mode imaging revealed CNR close to zero dB until the temperature reached 50 °C causing necrosis. The data presented suggest that the proposed method could offer an alternative to MRI-guided temperature imaging for prediction of the location and extent of the thermal lesion prior to applying the

  3. Tough Shift

    DEFF Research Database (Denmark)

    Brewer, Robert S.; Verdezoto, Nervo; Holst, Thomas

    2015-01-01

    people to change their behavior at home. Leveraging prior research on encouraging reductions in residential energy use through game play, we introduce ShareBuddy: a casual mobile game intended to encourage players not only to reduce, but also to shift their electricity use. We conducted two field studies...... real-world resource use into a game....

  4. Study of response nonuniformity for the LHCb calorimeter module and the prototype of the CBM calorimeter module

    International Nuclear Information System (INIS)

    Korolko, I. E.; Prokudin, M. S.

    2009-01-01

    A spatial nonuniformity of the response to high-energy muons is studied in the modules of the LHCb electromagnetic calorimeter and the prototype of the calorimeter module with lead plates and scintillator tiles 0.5 mm thick. The nonuniformity of the response of the inner LHCb modules to 50-GeV electrons is also measured. Software is developed for a thorough simulation of light collection in scintillator plates of a shashlik calorimeter. A model is elaborated to describe light transmission from the initial scintillation to the wavelength-shifting fiber with a subsequent reradiation and propagation of light over the fiber to the photodetector. The results of the simulation are in good agreement with data.

  5. Resonant-state expansion of light propagation in nonuniform waveguides

    Science.gov (United States)

    Lobanov, S. V.; Zoriniants, G.; Langbein, W.; Muljarov, E. A.

    2017-05-01

    A rigorous approach for precise and efficient calculation of light propagation along nonuniform waveguides is presented. Resonant states of a uniform waveguide, which satisfy outgoing-wave boundary conditions, form a natural basis for expansion of the local electromagnetic field. Using such an expansion at fixed frequency, we convert the wave equation for light propagation in a nonuniform waveguide into an ordinary second-order matrix differential equation for the expansion coefficients depending on the coordinate along the waveguide. We illustrate the method on several examples of nonuniform planar waveguides and evaluate its efficiency compared to the aperiodic Fourier modal method and the finite element method, showing improvements of one to four orders of magnitude. A similar improvement can be expected also for applications in other fields of physics showing wave phenomena, such as acoustics and quantum mechanics.

  6. Microwave interaction with nonuniform hydrogen gas in carbon nanotubes

    International Nuclear Information System (INIS)

    Babaei, S.; Babaei, Sh.

    2009-01-01

    In this paper we study the reflection, absorption, and transmission of microwave from nonuniform hydrogen gas in carbon nanotubes, grown by iron-catalyzed high-pressure carbon monoxide disproportionate (HiPco) process. A discussion on the effect of various hydrogen gas parameters on the reflected power, absorbed power, and transmitted power is presented. The nonuniform hydrogen gas slab is modeled by a series of subslabs. The overall number density profile across the whole slab follows a parabolic function. The total reflected, absorbed, and transmitted powers are then deduced and their functional dependence on the number density, collision frequency, and angle of propagation is studied

  7. Non-uniformity of hot plastic strain of stainless steels with austenitic-ferritic structure

    International Nuclear Information System (INIS)

    Laricheva, L.P.; Peretyat'ko, V.N.; Rostovtsev, A.N.; Levius, A.M.

    1987-01-01

    Non-uniformity of hot strain of stainless steels of various alloying was investigated. Steels with austenite and δ-ferrite structure of two classes were chosen for investigation: 08Kh18N10T steel of austenitic class and 08Kh21N5T steel of austenitic-ferritic class. Tests were conducted for samples subjected to preliminary thermal treatment: heating up to 1250 deg C, holding during 0.5 h, cooling in water. The heat treatment enabled to produce large grains of austenite and δ-ferrite (about 30 μm) in 08Kh21N5T steel, and sufficient amount of δ-ferrite (up to 50%) in 08Kh18N10T steel. It is shown that hot strain of austenitic-ferritic steels is non-uniform. δ-ferrite strain is more pronounced as compared to austenite. The ratio of mean δ-ferrite strain to the mean austenite strain grows with increase of the degree of general steel strain and temperature. The ratio of mean phase strains in 08Kh18N10T steel is higher as compared to 08Kh21N5T steel, general strain and temperature being equal. Temperature effect on the ratio of δ-ferrite and austenite strains is more pronounced for 08Kh18N10T steel. It is explaind by the value of ratios of phase strain resistance and temperature effect on them

  8. Use of extremity insulation during whole body hyperthermia to reduce temperature nonuniformity

    International Nuclear Information System (INIS)

    Thrall, D.E.; Page, R.L.

    1987-01-01

    The author previously documented during whole body hyperthermia in dogs using a radiant heating device that temperature at superficial sites, including tibial bone marrow, falls below systemic arterial temperature during the plateau phase of heating. This may be due to direct heat loss to the environment. Sites where temperature is lower than systemic arterial temperature during the plateau phase may become sanctuary sites where tumor deposits are spared because they do not receive the prescribed thermal dose. In an attempt to decrease temperature nonuniformity and increase thermal dose delivered to such superficial sites, extremity insulation has been employed during whole body hyperthermia in dogs. The author measured temperature at cutaneous and subcutaneous sites and within tibial bone marrow in insulated and noninsulated extremities of dogs undergoing whole body hyperthermia in the radiant heating device. The author found that extremity insulation is effective in reducing extremity temperature nonuniformity. Specific results are presented. Extremity insulation may be necessary during whole body hyperthermia to assure that extremity tumor deposits receive a thermal dose similar to that prescribed for the entire body

  9. Shape Preserving Interpolatory Subdivision Schemes for Nonuniform Data

    NARCIS (Netherlands)

    Kuijt, F.; van Damme, Rudolf M.J.

    2002-01-01

    This article is concerned with a class of shape preserving four-point subdivision schemes which are stationary and which interpolate nonuniform univariate data {(xi, fi)}. These data are functional data, i.e., xi≠xj if i≠j. Subdivision for the strictly monotone x-values is performed by a subdivision

  10. Capacitated Vehicle Routing with Non-Uniform Speeds

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Molinaro, Marco; Nagarajan, Viswanath

    2011-01-01

    The capacitated vehicle routing problem (CVRP) [21] involves distributing (identical) items from a depot to a set of demand locations in the shortest possible time, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform...

  11. Field nonuniformity correction for quantitative analysis of digitized mammograms

    International Nuclear Information System (INIS)

    Pawluczyk, Olga; Yaffe, Martin J.

    2001-01-01

    Several factors, including the heel effect, variation in distance from the x-ray source to points in the image and path obliquity contribute to the signal nonuniformity of mammograms. To best use digitized mammograms for quantitative image analysis, these field non-uniformities must be corrected. An empirically based correction method, which uses a bowl-shaped calibration phantom, has been developed. Due to the annular spherical shape of the phantom, its attenuation is constant over the entire image. Remaining nonuniformities are due only to the heel and inverse square effects as well as the variable path through the beam filter, compression plate and image receptor. In logarithmic space, a normalized image of the phantom can be added to mammograms to correct for these effects. Then, an analytical correction for path obliquity in the breast can be applied to the images. It was found that the correction causes the errors associated with field nonuniformity to be reduced from 14% to 2% for a 4 cm block of material corresponding to a combination of 50% fibroglandular and 50% fatty breast tissue. A repeatability study has been conducted to show that in regions as far as 20 cm away from the chest wall, variations due to imaging conditions and phantom alignment contribute to <2% of overall corrected signal

  12. Josephson flux-flow oscillators in nonuniform microwave fields

    DEFF Research Database (Denmark)

    Salerno, Mario; Samuelsen, Mogens Rugholm

    2000-01-01

    We present a simple theory for Josephson flux-flow oscillators in the presence of nonuniform microwave fields. In particular we derive an analytical expression for the I-V characteristic of the oscillator from which we show that satellite steps are spaced around the main flux-flow resonance by only...

  13. Prediction of bed level variations in nonuniform sediment bed channel

    Indian Academy of Sciences (India)

    B R Andharia

    2018-04-12

    Apr 12, 2018 ... have been undertaken for measurements of bed and water levels in an aggrading channel due to overloading of nonuniform sediments ..... 2.4 Thickness of active bed layer. The mixing zone of sediment remaining in contact with the flow is referred as active layer (ABL). The thickness and particle size ...

  14. Absolute parametric instability in a nonuniform plane plasma ...

    Indian Academy of Sciences (India)

    The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is considered.

  15. Absolute parametric instability in a nonuniform plane plasma ...

    Indian Academy of Sciences (India)

    Abstract. The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is ...

  16. Instruction sequences and non-uniform complexity theory

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2008-01-01

    We develop theory concerning non-uniform complexity in a setting in which the notion of single-pass instruction sequence considered in program algebra is the central notion. We define counterparts of the complexity classes P/poly and NP/poly and formulate a counterpart of the complexity theoretic

  17. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; hide

    2017-01-01

    Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid

  18. Moessbauer study of local environment effects in the ordered Fe{sub 70}Al{sub 30} Invar alloy: Temperature dependence of isomer shift in the spin-glass phase

    Energy Technology Data Exchange (ETDEWEB)

    Delyagin, N.N., E-mail: delyagin@srd.sinp.msu.ru [Institute of Nuclear Physics, Moscow State University, 119991 Moscow (Russian Federation); Erzinkyan, A.L.; Parfenova, V.P.; Rozantsev, I.N. [Institute of Nuclear Physics, Moscow State University, 119991 Moscow (Russian Federation)

    2011-12-15

    The systematic studies of the magnetic hyperfine field distribution for {sup 57}Fe in the spin-glass (SG) phase of the ordered Fe{sub 70}Al{sub 30} Invar alloy have been performed using Moessbauer spectroscopy technique in the temperature range from 5 to 80 K. Particular emphasis has been placed on the low-field component of the distribution, which is considered as corresponding to the Fe sites in the SG magnetic configurations. The main result is the observation of the pronounced temperature dependence of isomer shift for several atomic SG configurations. The temperature behavior of the local electron density is strongly correlated to the Invar properties of the Fe{sub 70}Al{sub 30} alloy. We argue that the observed temperature dependence of the isomer shift due to a local volume effect. The temperature range, for which the pronounced decrease in atomic volume is observed, coincides with the range of the existence of the Invar effect. The influence of the competition between opposite in sign exchange interactions on the Invar properties is discussed. - Highlights: > Spin-glass phase of the ordered Fe{sub 70}Al{sub 30} Invar alloy has been investigated using Moessbauer spectroscopy technique. > Main result is the observation of the pronounced temperature dependence of isomer shifts for several atomic configurations. > Observed temperature dependencies due to a local volume effect. > Temperature variations of the isomer shifts are strongly correlated to the Invar properties of the Fe{sub 70}Al{sub 30} alloys.

  19. Shifting Blame?

    DEFF Research Database (Denmark)

    Garofalo, Orsola; Rott, Christina

    2017-01-01

    either the decision maker or a spokesperson communicates the decided allocation to recipients, who then determine whether to punish either of them. We find that receivers punish both the decision maker and the spokesperson more often, and more heavily, for unfair allocations communicated...... by the spokesperson if there is room for shifting blame. The increased punishment results from the messenger’s style of delivery: spokespersons are more likely than decision makers to express emotional regret instead of rational need. Receivers seem to punish the former style of communication because they view...

  20. Non-uniformity of Clinical Head, Head and Neck, and Body Coils in Magnetic Resonance Imaging (MRI

    Directory of Open Access Journals (Sweden)

    Mahmood Nazarpoor

    2014-11-01

    Full Text Available Introduction Signal intensity uniformity in a magnetic resonance (MR image indicates how well the MR imaging (MRI system represents an object. One of the major sources of image non-uniformity in high-field MRI scanners is inhomogeneity of radio-frequency coil. The aim of this study was to investigate non-uniformity in head, head and neck, and body coils and compare the obtained results to determine the best clinical coil for future clinical application. Materials and Methods A phantom was designed to investigate the non-uniformity of coils. All evaluations were carried out using a 1.5 T clinical MRI scanner. T1-weighted inversion recovery sequence (linear phase encoding and turbo fast low angle shot (TurboFLASH images were used to find non-uniformity in the clinical coils. For testing the uniformity of coils, signal intensity profiles in parts of the coronal image of phantom were measured over X and Y axes. Results The results showed that body coil was the most uniform coil of all; in addition, the head and neck coil was more uniform than the head coil. The results also indicated that signal-to-noise ratio (SNR of the head and neck coil was higher than the head and body coils. Moreover, SNR of the head coil was higher than that of the body coil. Conclusion In order to accurately find or apply an image signal intensity for measuring organ blood flow or perfusion, coil non-uniformity corrections are required.

  1. Shape Shifting

    DEFF Research Database (Denmark)

    Gottlieb, Stefan; Hundebøl, Jesper; Larsen, Casper Schultz

    2009-01-01

    In this paper we are concerned with the specific effects of a 3D building model produced and reproduced in the planning and construction phases on a particular construction project. We contrast these effects with the policy intentions expressed within a state funded, public initiative that aims...... to promote so-called ‘digital construction' in Denmark. One of the main objectives of this initiative is to ensure better coordination between the different phases of the building project through the application of 3D Building Information Models (BIM). The intentions are to improve the construction phase...... by providing pervasive on-site planning and logistics, where the 3D building model combined with process-data developed and maintained by the individual contractor should facilitate the production of detailed step-by-step production planning in the form of ‘production cards'. The empirical findings from...

  2. Nonuniform transformation field analysis of multiphase elasto viscoplastic materials: application to MOX fuels; Analyse par champs de transformation de materiaux elastoviscoplastiques multiphases: application aux combustibles MOX

    Energy Technology Data Exchange (ETDEWEB)

    Roussette, S

    2005-05-15

    The description of the overall behavior of nonlinear materials with nonlinear dissipative phases requires an infinity of internal variables. An approximate model involving only a finite number of internal variables, Nonuniform Transformation Field Analysis, is obtained by considering a decomposition of these variables on a finite set of nonuniform transformation fields, called plastic modes. The method is initially developed for incompressible elasto viscoplastic materials. Karhunen-Loeve expansion is proposed to optimize the plastic modes. Then the method is extended to porous elasto viscoplastic materials. Finally the transformation field analysis, developed by Dvorak, is applied to nuclear fuels MOX. This method enables to make sensitivity studies to determine the role of some microstructural parameters on the fuel behaviour. Moreover the adequacy of the nonuniform method for fuels MOX is shown, the final objective being to be able to apply the model to the MOX in 3D. (author)

  3. Shifting Sugars and Shifting Paradigms

    Science.gov (United States)

    Siegal, Mark L.

    2015-01-01

    No organism lives in a constant environment. Based on classical studies in molecular biology, many have viewed microbes as following strict rules for shifting their metabolic activities when prevailing conditions change. For example, students learn that the bacterium Escherichia coli makes proteins for digesting lactose only when lactose is available and glucose, a better sugar, is not. However, recent studies, including three PLOS Biology papers examining sugar utilization in the budding yeast Saccharomyces cerevisiae, show that considerable heterogeneity in response to complex environments exists within and between populations. These results join similar recent results in other organisms that suggest that microbial populations anticipate predictable environmental changes and hedge their bets against unpredictable ones. The classical view therefore represents but one special case in a range of evolutionary adaptations to environmental changes that all organisms face. PMID:25688600

  4. Shifting sugars and shifting paradigms.

    Directory of Open Access Journals (Sweden)

    Mark L Siegal

    2015-02-01

    Full Text Available No organism lives in a constant environment. Based on classical studies in molecular biology, many have viewed microbes as following strict rules for shifting their metabolic activities when prevailing conditions change. For example, students learn that the bacterium Escherichia coli makes proteins for digesting lactose only when lactose is available and glucose, a better sugar, is not. However, recent studies, including three PLOS Biology papers examining sugar utilization in the budding yeast Saccharomyces cerevisiae, show that considerable heterogeneity in response to complex environments exists within and between populations. These results join similar recent results in other organisms that suggest that microbial populations anticipate predictable environmental changes and hedge their bets against unpredictable ones. The classical view therefore represents but one special case in a range of evolutionary adaptations to environmental changes that all organisms face.

  5. Energy Cascade from Internal Modes in Non-uniformly Stratified Fluid through Excitation of Superharmonic Disturbances

    Science.gov (United States)

    Sutherland, B. R.

    2016-02-01

    It is well established that two-dimensional internal plane waves and modes in uniformly stratified fluid efficiently transfer energy to smaller scale waves and ultimately turbulent mixing through parametric subharmonic instability (PSI). The numerical simulations of MacKinnon & Winters (GRL 2005) predicted PSI should act efficiently to disrupt the internal tide. However, while in situ observations showed the presence of PSI, it was not found to be appreciable. One reason for the discrepancy between simulations and observations is that the former examined an internal mode in uniformly stratified fluid whereas, in reality, the internal tide exists in non-uniform stratification and is manifest as sinusoidal oscillations of the thermocline. Through theory supported by numerical simulations, it is shown that internal modes in non-uniform stratification immediately excite superharmonics, not subharmonic disturbances. These have double the horizontal wavenumber and double the frequency of the parent mode and hence move with the same horizontal phase speed of the parent mode. As the disturbances grow in amplitude, however, they interact with the parent mode generating small-scale vertically propagating internal waves within the strongly stratified layer. The occurrence of PSI over very long times can occur, as in the simulations of Hazewinkel and Winters (JPO 2011). However, a comprehensive understanding of the energy cascade from the internal tide to small scales must consider the evolution of excited superharmonic disturbances.

  6. Parametric instability of a nonuniform plasma near a linear focus

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipenko, V.I.; Budnikov, V.N.; Gusakov, E.Z.; Romanchuk, I.A.; Simonchik, L.V.

    1985-02-01

    Parametric instability l ..-->.. l'+s resulting in anomalous reflection of oblique Langmuir waves in a two-dimensionally nonuniform plasma is studied experimentally and theoretically. The experimental results confirm the theoretical prediction that for low input powers, the instability consists in the spatial amplification of ion-sound noise. The scattered signal is found to rise abruptly for spatial gains s> or approx. =10/sup 4/ because the threshold for absolute instability l ..-->.. l'+s is approached. The absolute instability saturates due to depletion of the pump wave, which is almost completely reflected. A mechanism for the generation of cascade parametric turbulence spectra is identified which is specific to nonuniform plasmas.

  7. Magnetostatic interactions in cylindrical nanostructures with non-uniform magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, O.J. [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Perez, L.M. [Departamento de Fisica y Matematica Aplicada, Universidad de Navarra, 31080 Pamplona (Spain); Laroze, D., E-mail: david.laroze@gmail.com [Max Planck Institute for Polymer Research, D 55021 Mainz (Germany); Instituto de Alta Investigacion, Universidad de Tarapaca, Casilla 7D, Arica (Chile); Altbir, D. [Departamento de Fisica and Center for the Development of Nanoscience and Nanotechnology, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago (Chile)

    2012-05-15

    Cylindrical magnetic nanostructures, like nanowires or nanotubes, should be used for the new generation of magnetic devices. Therefore, the investigation of inter-element interaction is an intense area of research. In this paper we investigated cylindrical nanostructures with non-uniform magnetization field. We focus on particles with a periodic magnetization function and using Fourier series we reduced the problem to a single integral expression. Analytical expressions for both, the self and the interaction magnetostatic energy, are given. These expressions are used to analyze multisegmented tubes, as a function of the number of segments and the distance between particles. - Highlights: Black-Right-Pointing-Pointer Magnetic cylindrical nanoparticles like nanowires or nanotubes. Black-Right-Pointing-Pointer Magnetostatic interaction between particles. Black-Right-Pointing-Pointer Non-uniform magnetization states.

  8. Measurement of reactivity effect caused by nonuniform fuel distribution

    International Nuclear Information System (INIS)

    Yamane, Yoshihiro; Hirano, Yasushi; Yasui, Hazime; Nishina, Kojiro; Shiroya, Seiji

    1991-01-01

    A reactivity effect due to a spatial variation of nuclear fuel concentration is an important problem in a reprocessing plant. To estimate this reactivity effect theoretically, the ''Goertzel's necessary condition, and th Fuel Importance'' theory have been proposed. In order to verify these theories, we have performed systematic measurements of reactivity effect due to the nonuniformity in the fuel distribution within the Kyoto University Critical Assembly. Neutron flux distribution and Fuel Importance distribution were also determined. A nonuniform assembly whose fuel concentration in the center region was 40% higher than the uniform one was found to have an excess reactivity of 0.3%Δk/k, with the same total uranium mass for which the uniform assembly was just critical. Moreover, its spatial distribution of thermal neutron flux and of Fuel Importance were more flat than those of the uniform assembly, as expected by the Goertzel's condition and the Fuel Importance theory. (Author)

  9. Object tracking under nonuniform illumination with adaptive correlation filtering

    Science.gov (United States)

    Picos, Kenia; Díaz-Ramírez, Víctor H.; Kober, Vitaly

    2013-09-01

    A real-time system for illumination-invariant object tracking is proposed. The system is able to estimate at high-rate the position of a moving target in an input scene when is corrupted by the presence of a high cluttering background and nonuniform illumination. The position of the target is estimated with the help of a filter bank of space-variant correlation filters. The filters in the bank, adapt their parameters according to the local statistical parameters of the observed scene in a small region centered at coordinates of a predicted position for the target in each frame. The prediction is carried out by exploiting information of present and past frames, and by using a dynamic motion model of the target in a two-dimensional plane. Computer simulation results obtained with the proposed system are presented and discussed in terms of tracking accuracy, computational complexity, and tolerance to nonuniform illumination.

  10. Phase shift of oscillatory magnetoresistance in a double-cross thin film structure of La0.3Pr0.4Ca0.3MnO3 via strain-engineered elongation of electronic domains

    Science.gov (United States)

    Alagoz, H. S.; Prasad, B.; Jeon, J.; Blamire, M. G.; Chow, K. H.; Jung, J.

    2018-02-01

    The subtle balance between the competing electronic phases in manganites due to complex interplay between spin, charge, and orbital degrees of freedom could allow one to modify the properties of electronically phase separated systems. In this paper, we show that the phase shift in the oscillatory magnetoresistance ρ (θ ) can be modified by engineering strain driven elongation of electronic domains in La0.3Pr0.4Ca0.3MnO3 (LPCMO) thin films. Strain-driven elongation of magnetic domains can produce different percolation paths and hence different anisotropic magnetoresistance responses. This tunability provides a unique control that is unattainable in conventional 3 d ferromagnetic metals and alloys.

  11. Using Nonuniform Fiber to Generate Slow Light via SBS

    Directory of Open Access Journals (Sweden)

    Wenhai Li

    2008-01-01

    Full Text Available The data pulse delay based on slow light induced by stimulated Brillouin scattering (SBS in a nonuniform dispersion decreasing fiber (DDF is demonstrated experimentally, and the distortions of data pulses at different beat frequencies are studied. We found that a delay exceeding a pulse width can be achieved at particular beat frequency, and the DDF has larger delay versus gain slope coefficient with much better output pulse quality than single-mode fiber.

  12. The gauge theory of dislocations: A nonuniformly moving screw dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, Markus, E-mail: lazar@fkp.tu-darmstadt.d [Emmy Noether Research Group, Department of Physics, Darmstadt University of Technology, Hochschulstr. 6, D-64289 Darmstadt (Germany); Department of Physics, Michigan Technological University, Houghton, MI 49931 (United States)

    2010-07-05

    We investigate the nonuniform motion of a straight screw dislocation in infinite media in the framework of the translational gauge theory of dislocations. The equations of motion are derived for an arbitrarily moving screw dislocation. The fields of the elastic velocity, elastic distortion, dislocation density and dislocation current surrounding the arbitrarily moving screw dislocation are derived explicitly in the form of integral representations. We calculate the radiation fields and the fields depending on the dislocation velocities.

  13. A Grobman-Hartman theorem for nonuniformly hyperbolic dynamics

    Science.gov (United States)

    Barreira, Luis; Valls, Claudia

    We establish a version of the Grobman-Hartman theorem in Banach spaces for nonuniformly hyperbolic dynamics. We also consider the case of sequences of maps, which corresponds to a nonautonomous dynamics with discrete time. More precisely, we consider sequences of Lipschitz maps A+f such that the linear parts A admit a nonuniform exponential dichotomy, and we establish the existence of a unique sequence of topological conjugacies between the maps A+f and A. Furthermore, we show that the conjugacies are Hölder continuous, with Hölder exponent determined by the ratios of Lyapunov exponents with the same sign. To the best of our knowledge this statement appeared nowhere before in the published literature, even in the particular case of uniform exponential dichotomies, although some experts claim that it is well known in this case. We are also interested in the dependence of the conjugacies on the perturbations f: we show that it is Hölder continuous, with the same Hölder exponent as the one for the conjugacies. We emphasize that the additional work required to consider the case of nonuniform exponential dichotomies is substantial. In particular, we need to consider several additional Lyapunov norms.

  14. NOTE ON TRAVEL TIME SHIFTS DUE TO AMPLITUDE MODULATION IN TIME-DISTANCE HELIOSEISMOLOGY MEASUREMENTS

    International Nuclear Information System (INIS)

    Nigam, R.; Kosovichev, A. G.

    2010-01-01

    Correct interpretation of acoustic travel times measured by time-distance helioseismology is essential to get an accurate understanding of the solar properties that are inferred from them. It has long been observed that sunspots suppress p-mode amplitude, but its implications on travel times have not been fully investigated so far. It has been found in test measurements using a 'masking' procedure, in which the solar Doppler signal in a localized quiet region of the Sun is artificially suppressed by a spatial function, and using numerical simulations that the amplitude modulations in combination with the phase-speed filtering may cause systematic shifts of acoustic travel times. To understand the properties of this procedure, we derive an analytical expression for the cross-covariance of a signal that has been modulated locally by a spatial function that has azimuthal symmetry and then filtered by a phase-speed filter typically used in time-distance helioseismology. Comparing this expression to the Gabor wavelet fitting formula without this effect, we find that there is a shift in the travel times that is introduced by the amplitude modulation. The analytical model presented in this paper can be useful also for interpretation of travel time measurements for the non-uniform distribution of oscillation amplitude due to observational effects.

  15. Stable phase-shift despite quasi-rhythmic movements: a CPG-driven dynamic model of active tactile exploration in an insect

    Directory of Open Access Journals (Sweden)

    Nalin eHarischandra

    2015-08-01

    Full Text Available An essential component of autonomous and flexible behaviour in animals is active exploration of the environment, allowing for perception-guided planning and control of actions. An important sensory system involved is active touch. Here, we introduce a general modelling framework of Central Pattern Generators (CPGs for movement generation in active tactile exploration behaviour. The CPG consists of two network levels: (i phase-coupled Hopf oscillators for rhythm generation, and (ii pattern formation networks for capturing the frequency and phase characteristics of individual joint oscillations. The model captured the natural, quasi-rhythmic joint kinematics as observed in coordinated antennal movements of walking stick insects. Moreover, it successfully produced tactile exploration behaviour on a three-dimensional skeletal model of the insect antennal system with physically realistic parameters. The effect of proprioceptor ablations could be simulated by changing the amplitude and offset parameters of the joint oscillators, only. As in the animal, the movement of both antennal joints was coupled with a stable phase difference, despite the quasi-rhythmicity of the joint angle time courses. We found that the phase-lead of the distal scape-pedicel joint relative to the proximal head-scape joint was essential for producing the natural tactile exploration behaviour and, thus, for tactile efficiency. For realistic movement patterns, the phase-lead could vary within a limited range of 10 to 30 degrees only. Tests with artificial movement patterns strongly suggest that this phase sensitivity is not a matter of the frequency composition of the natural movement pattern. Based on our modelling results, we propose that a constant phase difference is coded into the CPG of the antennal motor system and that proprioceptors are acting locally to regulate the joint movement amplitude.

  16. Non-uniform interhemispheric temperature trends over the past 550 years

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, Richard P. [Landcare Research, PO Box 40, Lincoln (New Zealand); Lincoln University, Bio-Protection Research Centre, PO Box 84, Lincoln (New Zealand); Fenwick, Pavla; Palmer, Jonathan G. [Gondwana Tree-ring Laboratory, PO Box 14, Canterbury (New Zealand); McGlone, Matt S. [Landcare Research, PO Box 40, Lincoln (New Zealand); Turney, Chris S.M. [University of Exeter, School of Geography, Exeter (United Kingdom)

    2010-12-15

    The warming trend over the last century in the northern hemisphere (NH) was interrupted by cooling from ad 1940 to 1975, a period during which the southern hemisphere experienced pronounced warming. The cause of these departures from steady warming at multidecadal timescales are unclear; the prevailing explanation is that they are driven by non-uniformity in external forcings but recent models suggest internal climate drivers may play a key role. Paleoclimate datasets can help provide a long-term perspective. Here we use tree-rings to reconstruct New Zealand mean annual temperature over the last 550 years and demonstrate that this has frequently cycled out-of-phase with NH mean annual temperature at a periodicity of around 30-60 years. Hence, observed multidecadal fluctuations around the recent warming trend have precedents in the past, strongly implicating natural climate variation as their cause. We consider the implications of these changes in understanding and modelling future climate change. (orig.)

  17. Charged particle and photon acceleration by wakefield plasma waves in non-uniform plasmas

    International Nuclear Information System (INIS)

    Bulanov, S.V.; Kirsanov, V.I.; Sakharov, A.S.; Pegoraro, F.

    1993-01-01

    We discuss the acceleration of charged particles and the upshift of the frequency of short wave packets of laser radiation. The acceleration and the upshift are caused by wake plasma waves excited by a strong laser pulse in a non-uniform plasma. We show that unlimited acceleration of charged particles is possible for specific spatial dependencies of the plasma density. In this unlimited acceleration regime, particles have a fixed phase relationship with respect to the plasma wave, while their energy increases with time. When the wave breaking limit is approached and surpassed, the efficiency of the acceleration of the charged particles and of the frequency upshift of the photons can be increased significantly. (author) 3 refs

  18. Characteristics of radiation syndromes caused by nonuniform irradiation

    International Nuclear Information System (INIS)

    Avetisov, G.M.; Darenskaya, N.G.; Zajtseva, R.N.

    1975-01-01

    The quantitative characteristics of the development of hemopoietic, intestinal and oral syndromes were studied on male rats subjected to uniform, general non-uniform and partial (head, adbomen, anterior and posterior abdomen sections, and hind part of body) X-raying (180-250 kV, 60-200 R/min). The hemopoietic syndrome resulted in death at uniform irradiation intensities of 400-700R; with screening of the abdominal cavity, irradiation was increased to 850 R. The dosages for intestinal and oral syndromes at partial irradiation of the abdominal cavity and head were equal to 1,150-1,500 and 1,400-1,800 R, respectively

  19. Non-Uniform Compressive Strength of Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Nøkkentved, Alexandros; Lundsgaard-Larsen, Christian; Berggreen, Carl Christian

    2005-01-01

    debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing...... of applying a controlled non-uniform compressive load to the test panels requires a strong focus on the development of a suitable testrig. This is done by the extensive use of product development methods. The experimental results based on full-scale testing of 10 GFRP/foam core panels with prefabricated...

  20. A non-uniform expansion mechanical safety model of the stent.

    Science.gov (United States)

    Yang, J; Huang, N; Du, Q

    2009-01-01

    Stents have a serial unstable structure that readily leads to non-uniform expansion. Non-uniform expansion in turn creates a stent safety problem. We explain how a stent may be simplified to a serial unstable structure, and present a method to calculate the non-uniform expansion of the stent on the basis of the serial unstable structure. We propose a safety criterion based on the expansion displacement instead of the strain, and explain that the parameter Rd, the ratio of the maximum displacement of the elements to normal displacement, is meaningful to assess the safety level of the stent. We also examine how laser cutting influences non-uniform expansion. The examples illustrate how to calculate the parameter Rd to assess non-uniform expansion of the stent, and demonstrate how the laser cutting offset and strengthening coefficient of the material influence the stent expansion behaviour. The methods are valuable for assessing stent safety due to non-uniform expansion.

  1. Light beam diffraction on inhomogeneous holographic photonic PDLC structures under the influence of spatially non-uniform electric field

    Science.gov (United States)

    Semkin, A. O.; Sharangovich, S. N.

    2016-08-01

    In this work the theoretical model of two-dimensional Bragg diffraction of quasimonochromatic light beams on amplitude- and phase- inhomogeneous holographic photonic PDLC structures under the impact of spatially non-uniform electric field is proposed. The selfconsistent solutions for the light diffraction on PDLC structure with uniform amplitude and quasi-quadratic profiles are obtained for the case of influence of linearly varying electric field. The possibility to compensate the PDLC structure response inhomogeneity by the impact of non-unifrom external field is shown.

  2. Laterally excited flexible tanks with nonuniform density liquid

    International Nuclear Information System (INIS)

    Tang, Yu

    1996-01-01

    A study of the dynamic responses of flexible tanks containing nonuniform liquid under horizontal base excitations is presented. The system considered is an upright, circular cylindrical tank filled with an incompressible and inviscid liquid in which the density increases with the liquid depth. Only the impulsive components of response are considered in this study since the convective components can be computed by considering the tank to be rigid. It is shown in this study that for tanks with height-to-radius ratios between 0.3 and 1.2, the response quantities may be estimated utilizing the rigid tank solutions. Also, it is found that the pressure distribution along the tank wall is not sensitive to the detailed distribution function of the liquid density, and that the base shear and moments for the tank with nonuniform liquid can be estimated conservatively by assuming that the tank is filled with an equivalent uniform liquid density that preserves the total liquid weight. Finally, a simple equation for evaluating the fundamental natural frequency of the system is proposed

  3. Electrostatic adhesion of multiple non-uniformly charged dielectric particles

    Science.gov (United States)

    Kemp, B. A.; Whitney, J. G.

    2013-01-01

    Charged particle adhesion measurements can be as much as one order of magnitude higher than theoretical calculations. This discrepancy has ignited a debate as to the nature of the physics occurring with microscopic particle adhesion. Attempts to bring calculations closer to measured results have produced models that include multiple particle interactions, dielectric polarization, and non-uniform charge. Individually, each of these models can only produce a 2× to 5× enhancement in predicted adhesion force over simple Coulombic attraction. In this correspondence, an analytical model of electrostatic particle forces is developed, which allows for independent assignment of dielectric constant and non-uniform surface charge distribution to an arbitrary number of particles. Because the model can include an image plane, it is ideal for electrostatic adhesion calculations. Application to a monolayer of printed toner particles predicts nearly an order of magnitude increase in adhesion force over Coulombic attraction. These results are the first analytical results to place predictions of charged particle adhesion on the same order of magnitude with measurements.

  4. Adaptive enhancement for nonuniform illumination images via nonlinear mapping

    Science.gov (United States)

    Wang, Yanfang; Huang, Qian; Hu, Jing

    2017-09-01

    Nonuniform illumination images suffer from degenerated details because of underexposure, overexposure, or a combination of both. To improve the visual quality of color images, underexposure regions should be lightened, whereas overexposure areas need to be dimmed properly. However, discriminating between underexposure and overexposure is troublesome. Compared with traditional methods that produce a fixed demarcation value throughout an image, the proposed demarcation changes as local luminance varies, thus is suitable for manipulating complicated illumination. Based on this locally adaptive demarcation, a nonlinear modification is applied to image luminance. Further, with the modified luminance, we propose a nonlinear process to reconstruct a luminance-enhanced color image. For every pixel, this nonlinear process takes the luminance change and the original chromaticity into account, thus trying to avoid exaggerated colors at dark areas and depressed colors at highly bright regions. Finally, to improve image contrast, a local and image-dependent exponential technique is designed and applied to the RGB channels of the obtained color image. Experimental results demonstrate that our method produces good contrast and vivid color for both nonuniform illumination images and images with normal illumination.

  5. A novel boundary element method for nonuniform neutron diffusion problems

    International Nuclear Information System (INIS)

    Itagaki, Masafumi; Nisiyama, Shusuke; Tomioka, Satoshi; Enoto, Takeaki

    1999-01-01

    An advanced boundary element formulation has been proposed to solve the neutron diffusion equation (NDE) for a 'nonuniform' system. The continuous spatial distribution of a nuclear constant is assumed to be described using a polynomial function. Part of the constant term in the polynomial is left on the left-hand-side of the NDE, while the reminding is added to the fission source term on the right-hand-side to create a fictitious source. When the neutron flux is also expanded using a polynomial, the boundary integral equation corresponding to the NDE contains a domain integral related to the polynomial source. This domain integral is transformed into an infinite series of boundary integrals, by repeated application of the particular solution for a Poisson-type equation with the polynomial source. In two-dimensional, one-group test calculations for rectangular domains, the orthogonality of Legendre polynomials was used to determine the polynomial expansion coefficients. The results show good agreement with those obtained from finite difference computations in which the nonuniformity was approximated by a large number of material regions. (author)

  6. Absorption and impedance boundary conditions for phased geometrical-acoustics methods

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2012-01-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, both absorption coefficients and surface impedances of the boundary surfaces can be used, but no guideline has been...... developed on which boundary condition produces accurate results. In this study, various boundary conditions in terms of normal, random, and field incidence absorption coefficients and normal incidence surface impedance are used in a phased beam tracing model, and the simulated results are validated...... with boundary element solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. Effects of the neglect of reflection phase shift are also investigated. It is concluded that the impedance, random incidence, and field incidence absorption boundary conditions produce...

  7. An efficient IMPES-based, shifting matrix algorithm to simulate two-phase, immiscible flow in porous media with application to CO 2 sequestration in the subsurface

    KAUST Repository

    Salama, Amgad

    2012-01-01

    The flow of two or more immiscible fluids in porous media is ubiquitous particularly in oil industry. This includes secondary and tertiary oil recovery, CO2 sequestration, etc. Accurate predictions of the development of these processes are important in estimating the benefits, e.g., in the form of increased oil extraction, when using certain technology. However, this accurate prediction depends to a large extent on two things; the first is related to our ability to correctly characterize the reservoir with all its complexities and the second depends on our ability to develop robust techniques that solve the governing equations efficiently and accurately. In this work, we introduce a new robust and efficient numerical technique to solving the governing conservation laws which govern the movement of two immiscible fluids in the subsurface. This work will be applied to the problem of CO2 sequestration in deep saline aquifer; however, it can also be extended to incorporate more cases. The traditional solution algorithms to this problem are based on discretizing the governing laws on a generic cell and then proceed to the other cells within loops. Therefore, it is expected that, calling and iterating these loops several times can take significant amount of CPU time. Furthermore, if this process is done using programming languages which require repeated interpretation each time a loop is called like Matlab, Python or the like, extremely longer time is expected particularly for larger systems. In this new algorithm, the solution is done for all the nodes at once and not within loops. The solution methodology involves manipulating all the variables as column vectors. Then using shifting matrices, these vectors are sifted in such a way that subtracting relevant vectors produces the corresponding difference algorithm. It has been found that this technique significantly reduces the amount of CPU times compared with traditional technique implemented within the framework of

  8. Improved production of polygalacturonate lyase by combining a pH and online methanol control strategy in a two-stage induction phase with a shift in the transition phase.

    Science.gov (United States)

    Qureshi, Muhammad Salman; Zhang, Dongxu; Du, Guocheng; Chen, Jian

    2010-04-01

    Polygalacturonate lyase is a kind of enzyme that is abundantly used in the textile industry for cotton scouring. Previously, we reconstructed the polygalacturonate lyase gene in Pichia pastoris for the expression of this enzyme. To enhance the production of polygalacturonate lyase (PGL), a combined strategy was formulated by combining online methanol control and two-stage pH control strategies. For the two-stage pH control strategy during the growth phase, the pH was controlled at 5.5, and in the induction phase different pH levels were investigated for the optimum enzyme production. During the online methanol control strategy, the different levels of methanol (v/v) were investigated for the best enzyme production at pH 5.5. These two strategies were combined together for enhanced PGL productivity, and the induction phase was divided into two stages in which methanol concentrations were maintained at different levels online. The transition phase was introduced during the induction phase instead of introducing it after the growth phase. The two-stage combination strategy was formulated on the bases of methanol consumption of cells, optimal pH, cell viability and the production of polygalacturonate lyase by P. pastoris. By using this strategy, the production was doubled compared with common conditions, and the highest polygalacturonate lyase activity reached 1,631 U/ml. This strategy proved to be very useful for the enhancement of polygalacturonate lyase production by achieving higher cell viability, alcohol oxidase activity and phosphate-related compounds of the cells during the induction phase.

  9. Electron Beam Dose Distribution in the Presence of Non-Uniform Magnetic Field

    Directory of Open Access Journals (Sweden)

    Mohamad Javad Tahmasebi-Birgani

    2014-04-01

    Full Text Available Introduction Magnetic fields are capable of altering the trajectory of electron beams andcan be used in radiation therapy.Theaim of this study was to produce regions with dose enhancement and reduction in the medium. Materials and Methods The NdFeB permanent magnets were arranged on the electron applicator in several configurations. Then, after the passage of the electron beams (9 and 15 MeV Varian 2100C/D through the non-uniform magnetic field, the Percentage Depth Dose(PDDs on central axis and dose profiles in three depths for each energy were measured in a 3D water phantom. Results For all magnet arrangements and for two different energies, the surface dose increment and shift in depth of maximum dose (dmax were observed. In addition, the pattern of dose distribution in buildup region was changed. Measurement of dose profile showed dose localization and spreading in some other regions. Conclusion The results of this study confirms that using magnetic field can alter the dose deposition patterns and as a result can produce dose enhancement as well as dose reduction in the medium using high-energy electron beams. These effects provide dose distribution with arbitrary shapes for use in radiation therapy.

  10. Regional paleofire regimes affected by non-uniform climate, vegetation and human drivers.

    Science.gov (United States)

    Blarquez, Olivier; Ali, Adam A; Girardin, Martin P; Grondin, Pierre; Fréchette, Bianca; Bergeron, Yves; Hély, Christelle

    2015-09-02

    Climate, vegetation and humans act on biomass burning at different spatial and temporal scales. In this study, we used a dense network of sedimentary charcoal records from eastern Canada to reconstruct regional biomass burning history over the last 7000 years at the scale of four potential vegetation types: open coniferous forest/tundra, boreal coniferous forest, boreal mixedwood forest and temperate forest. The biomass burning trajectories were compared with regional climate trends reconstructed from general circulation models, tree biomass reconstructed from pollen series, and human population densities. We found that non-uniform climate, vegetation and human drivers acted on regional biomass burning history. In the open coniferous forest/tundra and dense coniferous forest, the regional biomass burning was primarily shaped by gradual establishment of less climate-conducive burning conditions over 5000 years. In the mixed boreal forest an increasing relative proportion of flammable conifers in landscapes since 2000 BP contributed to maintaining biomass burning constant despite climatic conditions less favourable to fires. In the temperate forest, biomass burning was uncoupled with climatic conditions and the main driver was seemingly vegetation until European colonization, i.e. 300 BP. Tree biomass and thus fuel accumulation modulated fire activity, an indication that biomass burning is fuel-dependent and notably upon long-term co-dominance shifts between conifers and broadleaf trees.

  11. Equilibrium configurations of the conducting liquid surface in a nonuniform electric field

    Science.gov (United States)

    Zubarev, N. M.; Zubareva, O. V.

    2011-01-01

    Possible equilibrium configurations of the free surface of a conducting liquid deformed by a nonuniform external electric field are investigated. The liquid rests on an electrode that has the shape of a dihedral angle formed by two intersecting equipotential half-planes (conducting wedge). It is assumed that the problem has plane symmetry: the surface is invariant under shift along the edge of the dihedral angle. A one-parametric family of exact solutions for the shape of the surface is found in which the opening angle of the region above the wedge serves as a parameter. The solutions are valid when the pressure difference between the inside and outside of the liquid is zero. For an arbitrary pressure difference, approximate solutions to the problem are constructed and it is demonstrated the approximation error is small. It is found that, when the potential difference exceeds a certain threshold value, equilibrium solutions are absent. In this case, the region occupied by the liquid disintegrates, the disintegration scenario depending on the opening angle.

  12. Non-uniform plastic deformation of micron scale objects

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    Significant increases in apparent flow strength are observed when non-uniform plastic deformation of metals occurs at the scale ranging from roughly one to ten microns. Several basic plane strain problems are analyzed numerically in this paper based on a new formulation of strain gradient...... that are not captured by conventional plasticity theory. These include the role of material length parameters in establishing the size dependence of strength and the elevation of resistance to plastic flow resulting from constraint on plastic flow at boundaries. Details of the finite element method employed...... in the numerical analysis of the higher order gradient theory will be discussed and related to prior formulations having some of the same features....

  13. Non-uniform plastic deformation of micron scale objects

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    Significant increases in apparent flow strength are observed when non-uniform plastic deformation of metals occurs at the scale ranging from roughly one to ten microns. Several basic plane strain problems are analyzed numerically in this paper based on a new formulation of strain gradient...... plasticity. The problems are the tangential and normal loading of a finite rectangular block of material bonded to rigid platens and having traction-free ends, and the normal loading of a half-space by a flat, rigid punch. The solutions illustrate fundamental features of plasticity at the micron scale...... that are not captured by conventional plasticity theory. These include the role of material length parameters in establishing the size dependence of strength and the elevation of resistance to plastic flow resulting from constraint on plastic flow at boundaries. Details of the finite element method employed...

  14. Vacuum polarisation in some static nonuniform magnetic fields

    International Nuclear Information System (INIS)

    Calucci, G.

    1995-11-01

    Vacuum polarisation in QED in presence of some configurations of external magnetic fields is investigated. The configuration considered correspond to fields is investigated. The configuration considered correspond to fields lying in a plane and without sources. The motion of a Dirac electron in this field configuration is studied and arguments are found to conclude that the lowest level gives the most important contribution. The result is that the main effect is not very different from the uniform case, the possibilities of calculating the corrections due to the uniformity is explicitly shown. A typical effect of nonuniformity of the field shows out in the refractivity of the field shows out in the refractivity of the vacuum

  15. Non-Uniform Heat Transfer in Thermal Regenerators

    DEFF Research Database (Denmark)

    Jensen, Jesper Buch

    , a numerical model, which simulates a single-blow operation in a parallel-plate regenerator, was developed and used to model the heat transfer under various conditions. In addition to the modeling of the heat transfer, a series of experiments on passive regenerators with non-uniform, but precisely controlled......, geometries was performed. The objective of performing these experiments was in part to eval- uate the direct applicability of the model, which only simulates one half of the regenerator cycle, to a practical situation where the regenerator is running con- tinuously by comparing the results gained......, and decreasing the plate spacing beoynd a certain point can even hurt the performance. Inter-channel heat transfer effects - or thermal cross-talk - have also been in- vestigated and the results show that not only the size of the plate spacings, but also their mutual order, can affect the heat transfer...

  16. Leveraging Non-Uniform Resources for Parallel Query Processing

    DEFF Research Database (Denmark)

    Mayr, Tobias; Bonnet, Philippe; Gehrke, Johannes

    2003-01-01

    Modular clusters are now composed of non- uniform nodes with different CPUs, disks or network cards so that customers can adapt the cluster configuration to the changing technologies and to their changing needs. This challenges dataflow parallelism as the primary load balancing technique...... of existing parallel database systems. We show in this paper that dataflow parallelism alone is ill suited for modular clusters because running the same operation on different subsets of the data can not fully utilize non-uniform hardware resources. We propose and evaluate new load balancing techniques...... that confirms the feasibility and effectiveness of the new techniques in a parallel execution engine prototype based on the open-source DBMS Predator....

  17. Novel application of chemical shift gradient echo in- and opposed-phase sequences in 3 T MRI for the detection of H-MRS visible lipids and grading of glioma.

    Science.gov (United States)

    Ramli, Norlisah; Khairy, Azua Mohd; Seow, Pohchoo; Tan, Li Kuo; Wong, Jeannie Hsiu Ding; Ganesan, Dharmendra; Rahmat, Kartini

    2016-07-01

    We evaluated the feasibility of using chemical shift gradient-echo (GE) in- and opposed-phase (IOP) imaging to grade glioma. A phantom study was performed to investigate the correlation of (1)H MRS-visible lipids with the signal loss ratio (SLR) obtained using IOP imaging. A cross-sectional study approved by the institutional review board was carried out in 22 patients with different glioma grades. The patients underwent scanning using IOP imaging and single-voxel spectroscopy (SVS) using 3T MRI. The brain spectra acquisitions from solid and cystic components were obtained and correlated with the SLR for different grades. The phantom study showed a positive linear correlation between lipid quantification at 0.9 parts per million (ppm) and 1.3 ppm with SLR (r = 0.79-0.99, p classification probabilities for grade II (SII = 1), grade III (SIII = 0.50) and grade IV (SIV = 0.89). The results underscore the lipid quantification differences in grades of glioma and provide a more comprehensive characterization by using SLR in chemical shift GE IOP imaging. SLR in IOP sequence demonstrates good performance in glioma grading. • Strong correlation was seen between lipid concentration and SLR obtained using IOP • IOP sequence demonstrates significant differences in signal loss within the glioma grades • SLR at solid tumour portions was the best measure for differentiation • This sequence is applicable in a research capacity for glioma staging armamentarium.

  18. Restoration of non-uniform exposure motion blurred image

    Science.gov (United States)

    Luo, Yuanhong; Xu, Tingfa; Wang, Ningming; Liu, Feng

    2014-11-01

    Restoring motion-blurred image is the key technologies in the opto-electronic detection system. The imaging sensors such as CCD and infrared imaging sensor, which are mounted on the motion platforms, quickly move together with the platforms of high speed. As a result, the images become blur. The image degradation will cause great trouble for the succeeding jobs such as objects detection, target recognition and tracking. So the motion-blurred images must be restoration before detecting motion targets in the subsequent images. On the demand of the real weapon task, in order to deal with targets in the complex background, this dissertation uses the new theories in the field of image processing and computer vision to research the new technology of motion deblurring and motion detection. The principle content is as follows: 1) When the prior knowledge about degradation function is unknown, the uniform motion blurred images are restored. At first, the blur parameters, including the motion blur extent and direction of PSF(point spread function), are estimated individually in domain of logarithmic frequency. The direction of PSF is calculated by extracting the central light line of the spectrum, and the extent is computed by minimizing the correction between the fourier spectrum of the blurred image and a detecting function. Moreover, in order to remove the strip in the deblurred image, windows technique is employed in the algorithm, which makes the deblurred image clear. 2) According to the principle of infrared image non-uniform exposure, a new restoration model for infrared blurred images is developed. The fitting of infrared image non-uniform exposure curve is performed by experiment data. The blurred images are restored by the fitting curve.

  19. THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Line, Michael R. [NASA Ames Research Center, Moffet Field, CA 94035 (United States); Parmentier, Vivien, E-mail: mrline@ucsc.edu [Department of Astronomy and Astrophysics, University of California–Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2016-03-20

    We model the impact of nonuniform cloud cover on transit transmission spectra. Patchy clouds exist in nearly every solar system atmosphere, brown dwarfs, and transiting exoplanets. Our major findings suggest that fractional cloud coverage can exactly mimic high mean molecular weight atmospheres and vice versa over certain wavelength regions, in particular, over the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) bandpass (1.1–1.7 μm). We also find that patchy cloud coverage exhibits a signature that is different from uniform global clouds. Furthermore, we explain analytically why the “patchy cloud-high mean molecular weight” degeneracy exists. We also explore the degeneracy of nonuniform cloud coverage in atmospheric retrievals on both synthetic and real planets. We find from retrievals on a synthetic solar composition hot Jupiter with patchy clouds and a cloud-free high mean molecular weight warm Neptune that both cloud-free high mean molecular weight atmospheres and partially cloudy atmospheres can explain the data equally well. Another key finding is that the HST WFC3 transit transmission spectra of two well-observed objects, the hot Jupiter HD 189733b and the warm Neptune HAT-P-11b, can be explained well by solar composition atmospheres with patchy clouds without the need to invoke high mean molecular weight or global clouds. The degeneracy between high molecular weight and solar composition partially cloudy atmospheres can be broken by observing the molecular Rayleigh scattering differences between the two. Furthermore, the signature of partially cloudy limbs also appears as a ∼100 ppm residual in the ingress and egress of the transit light curves, provided that the transit timing is known to seconds.

  20. Analyte preconcentration in nanofluidic channels with nonuniform zeta potential

    Science.gov (United States)

    Eden, A.; McCallum, C.; Storey, B. D.; Pennathur, S.; Meinhart, C. D.

    2017-12-01

    It is well known that charged analytes in the presence of nonuniform electric fields concentrate at locations where the relevant driving forces balance, and a wide range of ionic stacking and focusing methods are commonly employed to leverage these physical mechanisms in order to improve signal levels in biosensing applications. In particular, nanofluidic channels with spatially varying conductivity distributions have been shown to provide increased preconcentration of charged analytes due to the existence of a finite electric double layer (EDL), in which electrostatic attraction and repulsion from charged surfaces produce nonuniform transverse ion distributions. In this work, we use numerical simulations to show that one can achieve greater levels of sample accumulation by using field-effect control via wall-embedded electrodes to tailor the surface potential heterogeneity in a nanochannel with overlapped EDLs. In addition to previously demonstrated stacking and focusing mechanisms, we find that the coupling between two-dimensional ion distributions and the axial electric field under overlapped EDL conditions can generate an ion concentration polarization interface in the middle of the channel. Under an applied electric field, this interface can be used to concentrate sample ions between two stationary regions of different surface potential and charge density. Our numerical model uses the Poisson-Nernst-Planck system of equations coupled with the Stokes equation to demonstrate the phenomenon, and we discuss in detail the driving forces behind the predicted sample enhancement. The numerical velocity and salt concentration profiles exhibit good agreement with analytical results from a simplified one-dimensional area-averaged model for several limiting cases, and we show predicted amplification ratios of up to 105.

  1. THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA

    International Nuclear Information System (INIS)

    Line, Michael R.; Parmentier, Vivien

    2016-01-01

    We model the impact of nonuniform cloud cover on transit transmission spectra. Patchy clouds exist in nearly every solar system atmosphere, brown dwarfs, and transiting exoplanets. Our major findings suggest that fractional cloud coverage can exactly mimic high mean molecular weight atmospheres and vice versa over certain wavelength regions, in particular, over the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) bandpass (1.1–1.7 μm). We also find that patchy cloud coverage exhibits a signature that is different from uniform global clouds. Furthermore, we explain analytically why the “patchy cloud-high mean molecular weight” degeneracy exists. We also explore the degeneracy of nonuniform cloud coverage in atmospheric retrievals on both synthetic and real planets. We find from retrievals on a synthetic solar composition hot Jupiter with patchy clouds and a cloud-free high mean molecular weight warm Neptune that both cloud-free high mean molecular weight atmospheres and partially cloudy atmospheres can explain the data equally well. Another key finding is that the HST WFC3 transit transmission spectra of two well-observed objects, the hot Jupiter HD 189733b and the warm Neptune HAT-P-11b, can be explained well by solar composition atmospheres with patchy clouds without the need to invoke high mean molecular weight or global clouds. The degeneracy between high molecular weight and solar composition partially cloudy atmospheres can be broken by observing the molecular Rayleigh scattering differences between the two. Furthermore, the signature of partially cloudy limbs also appears as a ∼100 ppm residual in the ingress and egress of the transit light curves, provided that the transit timing is known to seconds

  2. Dietary supplementation with essence of chicken enhances daily oscillations in plasma glucocorticoid levels and behavioral adaptation to the phase-shifted environmental light–dark cycle in mice

    Directory of Open Access Journals (Sweden)

    Adila Dilixiati

    2017-08-01

    Full Text Available Maintenance of circadian rhythms is essential to many aspects of human health, including metabolism and neurological and psychiatric well-being. Chronic disruption of circadian clock function is implicated in increasing the risk of metabolic syndrome, cardiovascular events and development of cancers. However, there are little approaches to reinforce the function of circadian clock for prevention of these diseases. Essence of Chicken (EC is a nutritional supplement that is traditionally made by extracting water soluble substances derived from cooking the whole chicken. In this study, we found that dietary supplementation with EC enhanced circadian oscillation of glucocorticoid secretion in mice, and this was accompanied by enhancement of circadian oscillation in the adrenal expression of steroidogenic acute regulatory (StAR protein that mediates the rate-limiting step of glucocorticoid synthesis. Furthermore, EC facilitated re-entrainment of behavioral rhythm in mice when phase of the light–dark cycle was suddenly advanced. These results suggest that intake of EC has enhancement effect on circadian clock function in mice, which may contribute to sustain health and also offer new preventive strategies against circadian-related diseases.

  3. Experimental study of the reaction π-p → π0π0n at 2.01 GeV/c. Its use in a simultaneous phase shift analysis of the ππ channels

    International Nuclear Information System (INIS)

    David, Marc.

    1979-09-01

    We report results on π + π - → π 0 π 0 total and differential cross sections from threshold to 1.1 GeV ππ mass. These results have been obtained from a high-statistics experiment studying the reaction π - p → π 0 π 0 n at 2.01 GeV/c incident π - momentum with the Chew-Low extrapolation method. The π 0 's have been detected and their momenta analyzed in a large-gap cylindrical spark chamber placed in a magnetic field. The results show three salient features: 1) a large I = 0 production with sigmasub(tot) (π + π - → π 0 π 0 ) approaching the S-wave unitary limit in the 550-750 MeV ππ mass region, without any narrow structure; 2) a slow fall of sigma sub(tot) (π + π - → π 0 π 0 ) in the region of 750-950 MeV ππ mass. This feature is not predicted by the 'down' solution for the I = 0 S-wave ππ phase shift which has been reported recently; 3) The presence of D wave effects above 850 MeV as indicated by our extrapolated angular distributions. We have used the preceding results in an energy independent phase shift analysis of the 4 measurable ππ scattering channels. This analysis covers the energy range from threshold to 1200 MeV ππ mass. A unique solution is obtained which gives information on the S 0 scattering length (a 0 = 0.50 + - 0.09) and on epsilon 0 (710MeV) and S 0 * (974 MeV) structures [fr

  4. Design and cold flow test of a scramjet nozzle with nonuniform inflow

    Science.gov (United States)

    Mo, Jianwei; Xu, Jinglei; Quan, Zhibin; Yu, Kaikai; Lv, Zheng

    2015-03-01

    Dramatic differences in lift and pitching moment of a scramjet nozzle are inevitably produced when its inlet is nonuniform. A rotational method of characteristics computer program which takes into account the non-uniform inflow effects has been developed for designing asymmetric scramjet nozzles. Typical design cases with a given non-uniform Mach number profile and the corresponding mass-weighted average uniform Mach number profile were developed. Then, three-dimensional computational fluid dynamics analyses and cold flow experimental measurements were conducted to quantify performance improvement of the nozzle with the non-uniform design. Both the computation and experiment results indicate that the nozzle design with the non-uniform Mach number profile always exhibit better performance than the design with the uniform Mach number profile, particularly for lift and pitching moment. Compared with the nozzle design with uniform inflow, the improvement of axial thrust coefficient in the nozzle design with non-uniform inflow is approximately 1.75% at the design point, with a nozzle pressure ratio of 35. Moreover, the benefits on lift and pitching moment coefficients of the nozzle design with non-uniform inflow are approximately 6.51% and 6.35% at the design point, respectively. These results confirm that considering non-uniform distribution of the entrance flow parameters of a scramjet nozzle is necessary.

  5. Radio-frequency properties of stacked long Josephson junctions with nonuniform bias current distribution

    DEFF Research Database (Denmark)

    Filatrella, G; Pedersen, Niels Falsig

    1999-01-01

    We have numerically investigated the behavior of stacks of long Josephson junctions considering a nonuniform bias profile. In the presence of a microwave field the nonuniform bias, which favors the formation of fluxons, can give rise to a change of the sequence of radio-frequency induced steps...

  6. Parallel processing and non-uniform grids in global air quality modeling

    NARCIS (Netherlands)

    Berkvens, P.J.F.; Bochev, Mikhail A.

    2002-01-01

    A large-scale global air quality model, running efficiently on a single vector processor, is enhanced to make more realistic and more long-term simulations feasible. Two strategies are combined: non-uniform grids and parallel processing. The communication through the hierarchy of non-uniform grids

  7. Stochastic electromagnetic plane-wave pulse with non-uniform correlation distribution

    International Nuclear Information System (INIS)

    Ding, Chaoliang; Cai, Yangjian; Zhang, Yongtao; Wang, Haixia; Zhao, Zhiguo; Pan, Liuzhan

    2013-01-01

    Stochastic electromagnetic plane-wave (SEPW) pulse with non-uniform correlation distribution is introduced. The realizability condition for such pulse is derived. It is found that the evolution properties of the intensity and the degree of polarization of an SEPW pulse with non-uniform correlation distribution in dispersive media are much different from those of an SEPW pulse with uniform correlation distribution.

  8. Wastewater diffusive dilution and sedimentation of the fine contaminated particles for nonuniform flow in open channels

    Directory of Open Access Journals (Sweden)

    Lyapin Anton

    2018-01-01

    Full Text Available The influence of non-uniformity on mass transfer processes in open channels have been investigated under the action of urbanization factors. The study is related to the urgent problem of environmental degradation of water objects in urbanized areas. It is known that the water quality in the water objects depends on the manner in which the contaminants spread how they mix with the river water and diluted by it. The main results of the study consist of recommendations to incorporate non-uniformity factor to the calculation of diffusion dilution of wastewater and prediction of river processes. So the effect of the flow non-uniformity on the diffusion model of pollutants dilution and diffusion coefficient have been investigated. Formulas for the concentration profiles calculating and the average concentration of fine particulate matter in nonuniform gradually varied flow were presented. The deposition length of suspended contaminants were received, based on the hydraulic resistance laws of nonuniform gradually varied flow.

  9. Non-uniformity calibration for MWIR polarization imagery obtained with integrated microgrid polarimeters

    Science.gov (United States)

    Liu, Hai-Zheng; Shi, Ze-Lin; Feng, Bin; Hui, Bin; Zhao, Yao-Hong

    2016-03-01

    Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30 40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.

  10. Influence of nonuniformity of the submerged perforated sheet on steam demand leveling on the evaporation surface of a VVER steam generator

    Science.gov (United States)

    Blinkov, V. N.; Elkin, I. V.; Emelianov, D. A.; Melikhov, V. I.; Melikhov, O. I.; Nerovnov, A. A.; Nikonov, S. M.; Parfenov, Y. V.

    2016-01-01

    The results of a calculation and experimental research of the influence of nonuniformity of the submerged perforated sheet on steam demand leveling on the evaporation surface are published in the current article. A short description of the PGV test facility and a measuring system whose test section is a transverse "cut" of an actual PGV-1000 steam generator with the internals is presented. The methods of experimental starts are explained and instrumentations are described. A uniformly perforated sheet with the flow section of 5.7% and a nonuniformly perforated sheet with the flow section of 4.3% on the cold half and 8.1% on the hot half were used in the experiments. The system pressure was approximately 7 MPa, the inlet steam flow rate was varied between 4.23 and 7.94 t/h, i.e., the steam velocity on the evaporation surface was 0.15-0.29 m/s. The experimental results were analyzed with (1) the engineering method based on estimating the flow rates of steam on hot and cold half by the experimental values of the pressure drop on submerged list and (2) the STEG code, which was developed for three-dimensional mathematical modeling of the two-phase thermohydraulics in the heat exchanger volume and upgraded. It was established that changing the perforation from a uniform to a nonuniform one increases the residual nonuniformity coefficient, which characterizes the flow of steam from the hot side to the cold side under the sheet. However, the steam separation becomes worse because of a high local residual nonuniformity coefficients near the border of two plates with different perforation levels.

  11. Stowage Planning in Multiple Ports with Shifting Fee Minimization

    Directory of Open Access Journals (Sweden)

    E. Zhang

    2018-01-01

    Full Text Available This paper studies the problem of stowage planning within a vessel bay in a multiple port transportation route, aiming at minimizing the total container shifting fee. Since the access to containers is in the top-to-bottom order for each stack, reshuffle operations occur when a target container to be unloaded at its destination port is not stowed on the top of a stack at the time. Each container shift via a quay crane induces one unit of shifting fee that depends on the charge policy of the local container port. Previous studies assume that each container shift consumes a uniform cost in all ports and thus focus on minimizing the total number of shifts or the turnaround time of the vessel. Motivated by the observation that different ports are of nonuniform fee for each container shift, we propose a mixed integer programming (MIP model for the problem to produce an optimal stowage planning with minimum total shifting fee in this work. Moreover, as the considered problem is NP-hard due to the NP-hardness of its counterpart with uniform unit shifting fee, we propose an improved genetic algorithm to solve the problem. The efficiency of the proposed algorithm is demonstrated via numerical experiments.

  12. Special training of shift personnel

    International Nuclear Information System (INIS)

    Martin, H.D.

    1981-01-01

    The first step of on-the-job training is practical observation phase in an operating Nuclear Plant, where the participants are assigned to shift work. The simulator training for operating personnel, for key personnel and, to some extent, also for maintenance personnel and specialists give the practical feeling for Nuclear Power Plant behaviour during normal and abnormal conditions. During the commissioning phase of the own Nuclear Power Plant, which is the most important practical training, the participants are integrated into the commissioning staff and assisted during their process of practical learning by special instructors. The preparation for the licensing exams is vitally important for shift personnel and special courses are provided after the first non-nuclear trial operation of the plant. Personnel training also includes performance of programmes and material for retraining, training of instructors and assistance in building up special training programmes and material as well as training centers. (orig./RW)

  13. Contour propagation using non-uniform cubic B-splines for lung tumor delineation in 4D-CT.

    Science.gov (United States)

    Liu, Yongchuan; Jin, Renchao; Chen, Mi; Song, Enmin; Xu, Xiangyang; Zhang, Sheng; Hung, Chih-Cheng

    2016-12-01

    Accurate target delineation is a critical step in radiotherapy. In this study, a robust contour propagation method is proposed to help physicians delineate lung tumors in four-dimensional computer tomography (4D-CT) images efficiently and accurately. The proposed method starts with manually delineated contours on the reference phase. Each contour is fitted by a non-uniform cubic B-spline curve, and its deformation on the target phase is achieved by moving its control vertexes such that the intensity similarity between the two contours is maximized. Since contour is usually the boundary of lesion or tissue which may deform quite differently from the tissues outside the boundary, the proposed method treats each contour as a deformable entity, a non-uniform cubic B-spline curve, and focuses on the registration of contour entity instead of the entire image to avoid the deformation of contour to be smoothed by its surrounding tissues, meanwhile to greatly reduce the time consumption while keeping the accuracy of the contour propagation. Eighteen 4D-CT cases with 444 gross tumor volume (GTV) contours manually delineated slice by slice on the maximal inhale and exhale phases are used to verify the proposed method. The Jaccard similarity coefficient (JSC) between the propagated GTV and the manually delineated GTV is 0.885 ± 0.026, and the Hausdorff distance (HD) is [Formula: see text] mm. In addition, the time for propagating GTV to all the phases is 3.67 ± 3.41 minutes. The results are better than fast adaptive stochastic gradient descent (FASGD) B-spline method, 3D+t B-spline method and diffeomorphic Demons method. The proposed method is useful to help physicians delineate target volumes efficiently and accurately.

  14. Correcting circular non-uniform illumination of Sundanese lontar images

    Science.gov (United States)

    Hadi, S.; Suryani, M.; Paulus, E.; Supriatna, A. K.

    2017-10-01

    This paper presents the method for enhancing quality of degraded images which is essential for information automatic extraction from the digitized ancient manuscript known as lontar. The degraded lontar images have circular non-uniform illumination characteristics that are represented by more brightness on inner center of images and darker in the outer ellipse-like area of the images. The purpose of enhanced image processing is to leveling the distribution of pixels so the images have similar characteristics. The proposed method is developed based on DEWA Framework, a novel and optimized method for object detection, combined with background subtraction technique, which is implemented in several color spaces. Background images are estimated using morphological mathematics with specific type and size of structuring element. This estimation process has to be done due to the unavailability of exact background image captured during image acquisition step. Theoretical foundations of the proposed method along with experimental results are reported in this paper. The proposed method has been tested on 12 Sundanese lontar images which shows this approach is different and unique from most of the existing methods in this field of study. Experiment demonstrated the successful results of the method which is represented by displaying profile characteristics of each images on row 128.

  15. Evaluation of nonuniform field exposures with coupling factors.

    Science.gov (United States)

    Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; De Santis, Valerio; Onishi, Teruo

    2015-10-21

    In this study, the safety compliance for nonuniform field exposures is discussed using coupling factor concepts. The coupling factor, which is defined in the International Electrotechnical Commission 62311 standard, is extended to consider the effects of harmonics and also to apply to the specific absorption rate (for frequencies up to 30 MHz). The proposed compliance procedure is applied to and demonstrated for a prototype wireless power transfer (WPT) system with induction coupling operating at the fundamental frequency in 140 kHz band. First, measurements confirm that the perturbation of the external magnetic field strength and S11 parameter of a one-loop antenna by a human-equivalent phantom are sufficiently small, suggesting the applicability of the magneto-quasi-static approximation to frequencies up to 30 MHz. Then, the frequency characteristics of the coupling factor are derived for the WPT system. For the prototype system that is not optimized for commercial usage, the maximum allowable transmitting power is relaxed by a factor of 23 with the proposed procedure. The contribution of the harmonics decreased the allowable transmitting power by 39%, indicating their importance for safety compliance.

  16. The Influence of nonuniform activity distribution on cellular dosimetry

    International Nuclear Information System (INIS)

    Naling, Song; Yuan, Tian; Liangan, Zhang; Guangfu, Dai

    2008-01-01

    S value is an important parameter in determination of absorbed dose in nuclear medicine and radiobiology. The distribution of radioactivity shows significant influence on the S value especially in microdosimetry. In present work, a semi Monte Carlo Model is developed to calculate the microdosimetric cellular S value for different micro-distributions of radioactivity, i.e. uniform, linear increase, linear decrease, exponential increase, exponential decrease and centroid distribution. Emission of alpha particles is simulated by Monte Carlo model and the energy imparted to the target volume is calculated by the analytical Continuous Slowing Down Approximation (CSDA) model and the spline interpolation of range-energy relationship. We calculate tables of S values for 213 Po and 210 Po with various dimensions and most important with various possible micro-distributions of radioactivity, such as linear increase, linear decrease, exponential increase and exponential decrease. Then we compare the S values from cell to cell of uniform distribution with the Hamacher's results to test the feasibility of our model. S values of some nonuniform micro-distributions are compared to the corresponding data of the uniform distribution. The possible sources of these differences are theoretical analyzed. (author)

  17. Vertex function representation in non-uniform frequency grids

    Science.gov (United States)

    Tam, Ka-Ming; Yang, Shuxiang; Moreno, Juana; Jarrell, Mark

    2014-03-01

    The proper computer representation of many-body vertex functions is a central issue in computational many body methods such as the parquet formalism, a self-consistent two-particle field theory. Despite the great effort over the past two decades, its application is very limited. This is predominately due to two crucial factors - the stability of the iteration and the size of the memory allocation for the vertices. We previously demonstrated that the stability problem can be alleviated by explicitly restoring the crossing symmetry, making simulations beyond weak coupling for the Hubbard model feasible. The next step for the practical applications of the parquet formalism is to compress the memory required to represent the vertex. In this talk, we first demonstrate the problem of perturbation theory off the Matsubara frequency grids. This problem is avoided by working on the so-called decimation grids, which are non-uniform grids on Matsubara frequency. We then use this scheme in the parquet method, for solving an Anderson impurity problem. The results show substantial improvement compared to using the same number of uniform frequency grids. This may represent a crucial step towards practical applications of the parquet formalism for large clusters.

  18. Fluting Modes in Transversely Nonuniform Solar Flux Tubes

    Science.gov (United States)

    Soler, Roberto

    2017-12-01

    Magnetohydrodynamic waves of different types are frequently observed in magnetic flux tubes of the solar atmosphere and are often modeled using simple models. In the standard flux tube model made of a straight uniform tube with an abrupt boundary, transverse wave modes are classified according to their azimuthal wavenumber, m. Sausage (m = 0) and kink (m = 1) modes produce pulsations of the cross section and transverse oscillations of tube axis, respectively. Both sausage and kink modes have been observed in the solar atmosphere. Fluting (m≥slant 2) modes produce perturbations that are essentially confined around the boundary of the tube, I.e., they have a strong surface-like character. Unlike sausage and kink modes, the detection of fluting modes remains elusive. Here we show that the inclusion of transverse inhomogeneity in the flux tube model dramatically affects the properties of fluting modes. Even in a thin tube, kink and fluting modes are no longer degenerate in frequency when the tube has a smooth boundary. In addition, fluting modes become heavily damped by resonant absorption in a timescale shorter than the oscillation period. The perturbations loose their global shape and their distinctive surface-like appearance. As a consequence of that, we argue that nonuniform flux tubes with smooth boundaries may not be able to support fluting-like perturbations as coherent, global modes.

  19. Non-uniform dose distributions in cranial radiation therapy

    Science.gov (United States)

    Bender, Edward T.

    Radiation treatments are often delivered to patients with brain metastases. For those patients who receive radiation to the entire brain, there is a risk of long-term neuro-cognitive side effects, which may be due to damage to the hippocampus. In clinical MRI and CT scans it can be difficult to identify the hippocampus, but once identified it can be partially spared from radiation dose. Using deformable image registration we demonstrate a semi-automatic technique for obtaining an estimated location of this structure in a clinical MRI or CT scan. Deformable image registration is a useful tool in other areas such as adaptive radiotherapy, where the radiation oncology team monitors patients during the course of treatment and adjusts the radiation treatments if necessary when the patient anatomy changes. Deformable image registration is used in this setting, but there is a considerable level of uncertainty. This work represents one of many possible approaches at investigating the nature of these uncertainties utilizing consistency metrics. We will show that metrics such as the inverse consistency error correlate with actual registration uncertainties. Specifically relating to brain metastases, this work investigates where in the brain metastases are likely to form, and how the primary cancer site is related. We will show that the cerebellum is at high risk for metastases and that non-uniform dose distributions may be advantageous when delivering prophylactic cranial irradiation for patients with small cell lung cancer in complete remission.

  20. Alternative methods for evaluation of non-uniformity in nuclear medicine images

    International Nuclear Information System (INIS)

    Rasaneh, S.; Rajabi, H.; Hajizadeh, E.

    2005-01-01

    Non-uniformity test is the most essential in daily quality control procedures of nuclear medicine equipment's. However, the calculation of non-uniformity is hindered due to high level of noise in nuclear medicine data. Non-uniformity may be considered as a type of systematic error while noise is certainly a random error. The present methods of uniformity evaluation are not able to distinguish between systematic and random error and therefore produce incorrect results when noise is significant. In the present study, two hypothetical methods have been tested for evaluation of non-uniformity in nuclear medicine images. Materials and Methods: Using the Monte Carlo method, uniform and non-uniform flood images of different matrix sizes and different counts were generated. The uniformity of the images was calculated using the conventional method and proposed methods. The results were compared with the known non-uniformity data of simulated images. Results: It was observed that the value of integral uniformity never went below the recommended values except in small matrix size of high counts (more than 80 millions counts). The differential uniformity was quite insensitive to the degree of non-uniformity in large matrix size. Matrix size of 64*64 was only found to be suitable for the calculation of differential uniformity. It was observed that in uniform images, a small amount of non-uniformity changes the p-value of Kolmogorov-Smirnov test and noise amplitude of fast fourier transformation test significantly while the conventional methods failed to detect the nonuniformity. Conclusion: The conventional methods do not distinguish noise, which is always present in the data and occasional non-uniformity at low count density. In a uniform intact flood image, the difference between maximum and minimum pixel count (the value of integral uniformity) is much more than the recommended values for non-uniformity. After filtration of image, this difference decreases, but remains high

  1. OpenShift Workshop

    CERN Multimedia

    CERN. Geneva; Rodriguez Peon, Alberto

    2017-01-01

    Workshop to introduce developers to the OpenShift platform available at CERN. Several use cases will be shown, including deploying an existing application into OpenShift. We expect attendees to realize about OpenShift features and general architecture of the service.

  2. Phase-shift focus monitoring techniques

    Science.gov (United States)

    McQuillan, Matthew; Roberts, Bill

    2006-03-01

    Depth of focus (DOF) has become a victim of its mathematical relationship with Numerical Aperture (NA). While NA is being increased towards one to maximize scanner resolution capabilities, DOF is being minimized because of its inverse relationship with NA. Moore's law continues to drive the semiconductor industry towards smaller and smaller devices the need for high NA to resolve these shrinking devices will continue to consume the usable depth of focus (UDOF). Due to the shrinking UDOF a demand has been created for a feature or technology that will give engineers the capability to monitor scanner focus. Developing and implementation of various focus monitoring techniques have been used to prevent undetected tool focus excursions. Two overlay techniques to monitor ArF Scanner focus have been evaluated; our evaluation results will be presented here.

  3. Wind Shift Detection Model, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — On a daily basis, airport managers manually analyze current and future weather conditions to determine whether their facility will be negatively impacted. While not...

  4. Nonuniformities of electrical resistivity in undoped 6H-SiC wafers

    International Nuclear Information System (INIS)

    Li, Q.; Polyakov, A.Y.; Skowronski, M.; Sanchez, E.K.; Loboda, M.J.; Fanton, M.A.; Bogart, T.; Gamble, R.D.

    2005-01-01

    Chemical elemental analysis, temperature-dependent Hall measurements, deep-level transient spectroscopy, and contactless resistivity mapping were performed on undoped semi-insulating (SI) and lightly nitrogen-doped conducting 6H-SiC crystals grown by physical vapor transport (PVT). Resistivity maps of commercial semi-insulating SiC wafers revealed resistivity variations across the wafers between one and two orders of magnitude. Two major types of variations were identified. First is the U-shape distribution with low resistivity in the center and high in the periphery of the wafer. The second type had an inverted U-shape distribution. Secondary-ion-mass spectrometry measurements of the distribution of nitrogen concentration along the growth axis and across the wafers sliced from different locations of lightly nitrogen-doped 6H-SiC boules were conducted. The measured nitrogen concentration gradually decreased along the growth direction and from the center to the periphery of the wafers. This change gives rise to the U-like distribution of resistivity in wafers of undoped SI-SiC. The concentrations of deep electron traps exhibited similar dependence. Compensation of nitrogen donors by these traps can result in the inverted U-like distribution of resistivity. Possible reasons for the observed nonuniformities include formation of a (0001) facet in PVT growth coupled with orientation-dependent nitrogen incorporation, systematic changes of the gas phase composition, and increase of the deposition temperature during boule growth

  5. Compact Elliptically Tapered Slot Antenna with Non-uniform Corrugations for Ultra-wideband Applications

    Directory of Open Access Journals (Sweden)

    F. G. Zhu

    2013-04-01

    Full Text Available A small size elliptically tapered slot antenna (ETSA fed by coplanar waveguide (CPW for ultra-wideband (UWB applications is proposed. It is printed on an FR4 substrate and occupies a size of 37×34×0.8 mm^3. A pair of quarter circular shapes is etched on the radiator to reduce the size. To overcome the limitation of uniform corrugation, non-uniform corrugation is utilized to reduce the cross-polarization level. A parametric study is carried out to investigate the effects of circular cut and corrugations. In order to validate the design, a prototype is fabricated and measured. Both simulated and measured results confirm that the proposed antenna achieves a good performance of a reflection coefficient below -10 dB from 3.1 GHz to 10.6 GHz, including a maximum antenna gain of 8.1dBi, directional patterns in the end-fire direction, low cross-polarization level below -20 dB and linear phase response. The antenna is promising for applications in UWB impulse radar imaging.

  6. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    Science.gov (United States)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  7. Liquid jets injected into non-uniform crossflow

    Science.gov (United States)

    Tambe, Samir

    An experimental study has been conducted with liquid jets injected transversely into a crossflow to study the effect of non-uniformities in the crossflow velocity distribution to the jet behavior. Two different non-uniform crossflows were created during this work, a shear-laden crossflow and a swirling crossflow. The shear-laden crossflow was generated by merging two independent, co-directional, parallel airstreams creating a shear mixing layer at the interface between them. The crossflow exhibited a quasi-linear velocity gradient across the height of the test chamber. By varying the velocities of the two airstreams, the sense and the slope of the crossflow velocity gradient could be changed. Particle Image Velocimetry (PIV) studies were conducted to characterize the crossflow. The parameter, UR, is defined as the ratio of the velocities of the two streams and governs the velocity gradient. A positive velocity gradient was observed for UR > 1 and a negative velocity gradient for UR atomization of 0.5 mm diameter water jets injected into this crossflow. The crossflow velocity gradient was observed to have a significant effect on jet penetration as well as the post breakup spray. For high UR (> 1), jet penetration increased and the Sauter Mean Diameter (SMD) distribution became more uniform. For low UR (atomization were observed. The second crossflow tested was a swirling flow generated using in-house designed axial swirlers. Three swirlers were used, with vane exit angles of 30°, 45° and 60°. Laser Doppler Velocimetry (LDV) was used to study the crossflow velocities. The axial (Ux) and the tangential (Utheta) components of the crossflow velocity were observed to decrease with increasing radial distance away from the centerbody. The flow angle of the crossflow was smaller than the vane exit angle, with the difference increasing with the vane exit angle. Water jets were injected from a 0.5 mm diameter orifice located on a cylindrical centerbody. Multi-plane PIV

  8. Test of critical heat flux with non-uniform axial power shapes in rectangle narrow channel

    International Nuclear Information System (INIS)

    Xiong Wanyu; Wang Fei; Xiao Zejun; Lu Donghua

    2007-01-01

    Critical heat flux for axial non-uniform heat flux distribution in rectangle narrow channel was studied in this report. During the test, electric heating were adopted, and the axial direction power loaded were truncation cosine distribution. The de-ionized water was heated. The test result indicated that CHF with non-uniform axial heat flux distribution was lower than CHF with uniform axial heat flux distribution. A correction factor was used to analyze the test data. The semi-empirical relation of correction factor of CHF with axial non-uniform heat flux distribution had been obtained. Comparing to the existing correction factor models, it revealed that the proposed semi-empirical relation predictive CHF with axial non-uniform heat flux distribution in rectangle narrow channel was most accurate. (authors)

  9. Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

    Science.gov (United States)

    Bhat K, Srivatsa; Ganguli, Ranjan

    2018-02-01

    In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

  10. Analysis of Quantum Effects in Non-Uniformly Doped MOS Structures

    National Research Council Canada - National Science Library

    Fiegna, Claudio

    1997-01-01

    This paper presents results from the self-consistent solution of Schrodinger and Poisson equations obtained in one-dimensional non-uniformly doped MOS structures suitable for the fabrication of very short transistors...

  11. The magnetostriction in a superconductor-magnet system under non-uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xueyi; Jiang, Lang; Wu, Hao [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, Lanzhou University, Lanzhou, Gansu 730000 (China); Gao, Zhiwen, E-mail: gaozhw@lzu.edu.cn [Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

    2017-03-15

    Highlights: • We studied firstly magnetostriction in HTS under non-uniform magnetic field. • The superconductors may be homogeneous and nonhomogeneous. • The magnetostrictions response of the HTS is sensitive to the critical current density and amplitude of the applied magnetic field. • The magnetostriction of nonhomogeneous HTS is larger than that of homogeneous HTS. - Abstract: This paper describes a numerical model to examine the magnetostriction of bulk high-temperature superconductor (HTS) under non-uniform magnetic field in conjunction with finite element analysis. Through this model, the magnetostriction of homogeneous and nonhomogeneous HTS can be implemented under non-uniform magnetic field. Further, the effects of critical current density, applied field frequency and amplitude are also considered. The computational study can provide a fundamental mechanistic understanding the effects of non-uniform magnetic field on magnetostriction of HTS.

  12. Influence of adhesive non-uniformity on zero offset of micro accelerometer

    Science.gov (United States)

    Zhou, Wu; Li, Fei; Yu, Huijun; Qu, Hao; Hao, Rui; Wang, Dong; Sun, Sheng; Peng, Bei

    2017-12-01

    Adhesive attaching is a common method used in the packaging of high accurate MEMS devices. A full understanding of the effects of adhesive on device performance, therefore, plays a significant role in MEMS design because the thermal stress formed in packaging process highly depends on the shape, size, amount, properties and layout of the die attach adhesive. This paper investigates intensively the influence of adhesive nonuniformity in the sensitive direction of microaccelerometers on the distribution of thermal stress during the variation of environment temperature. The thermal stress will induce a movement of anchors and lead to nonzero voltage output of microaccelerometer. The influence of the adhesive with different levels of nonuniformity k on zero voltage output is investigated and the results show that the adhesive nonuniformity significantly influences the zero offset of the sensors, and the maximum one can reach 8.6 mV when nonuniformity factor is 0.975.

  13. Local full-wave energy in nonuniform plasmas

    International Nuclear Information System (INIS)

    Smithe, D.N.

    1988-10-01

    The subject of local wave energy in plasmas is treated via quasilinear theory from the dual perspectives of the action-angle formalism and gyrokinetics analysis. This work presents an extension to all orders in the gyroradius of the self-consistent wave-propagation/quasilinear-absorption problem using gyrokinetics. Questions of when and under what conditions local energy should be of definite sign are best answered using the action-angle formalism. An important result is that the ''dielectric operators'' of the linearized wave equation and of the local energy are not the same, a fact which is obscured when the eikonal or WKB assumption is invoked. Even though the two dielectrics are very different in character (one operates linearly on electric field for the plasma current, the other operates quadratically for the energy), it is demonstrated that they are nevertheless related by a simple mathematical statement. This study was originally motivated by concern and lively discussion over the questions of local energy for rf-heating of plasmas, where in certain instances, full-wave effects such as refraction, strong absorption, and mode conversion are of primary importance. Fundamentally, the rf-absorption must equate with the energy moment of the quasilinear term to achieve a correct energy balance. This fact governs the derivation (as opposed to postulation) of the local absorption. The troublesome ''kinetic flux'' may then be chosen (it is not unique) to satisfy a wave-energy balance relation with the Poynting flux and local absorption. It is shown that at least one such choice reduces asymptotically to the Stix form away from nonuniformities, thereby demonstrating energy conservation to all orders in Larmor radius. 25 refs

  14. Effect of fuel-air-ratio nonuniformity on emissions of nitrogen oxides

    Science.gov (United States)

    Lyons, V. J.

    1981-01-01

    The inlet fuel-air ratio nonuniformity is studied to deterine how nitrogen oxide (NOx) emissions are affected. An increase in NOx emissions with increased fuel-air ratio nonuniformity for average equivalence ratios less than 0.7 and a decrease in NOx emissions for average equivalence ratios near stoichiometric is predicted. The degree of uniformityy of fuel-air ratio profiles that is necessary to achieve NOx emissions goals for actual engines that use lean, premixed, prevaporized combustion systems is determined.

  15. Nonuniform grid implicit spatial finite difference method for acoustic wave modeling in tilted transversely isotropic media

    KAUST Repository

    Chu, Chunlei

    2012-01-01

    Discrete earth models are commonly represented by uniform structured grids. In order to ensure accurate numerical description of all wave components propagating through these uniform grids, the grid size must be determined by the slowest velocity of the entire model. Consequently, high velocity areas are always oversampled, which inevitably increases the computational cost. A practical solution to this problem is to use nonuniform grids. We propose a nonuniform grid implicit spatial finite difference method which utilizes nonuniform grids to obtain high efficiency and relies on implicit operators to achieve high accuracy. We present a simple way of deriving implicit finite difference operators of arbitrary stencil widths on general nonuniform grids for the first and second derivatives and, as a demonstration example, apply these operators to the pseudo-acoustic wave equation in tilted transversely isotropic (TTI) media. We propose an efficient gridding algorithm that can be used to convert uniformly sampled models onto vertically nonuniform grids. We use a 2D TTI salt model to demonstrate its effectiveness and show that the nonuniform grid implicit spatial finite difference method can produce highly accurate seismic modeling results with enhanced efficiency, compared to uniform grid explicit finite difference implementations. © 2011 Elsevier B.V.

  16. A Single-Chip 64-Channel Ultrasound RX-Beamformer Including Analog Front-End and an LUT for Non-Uniform ADC-Sample-Clock Generation.

    Science.gov (United States)

    Kim, Yoon-Jee; Cho, Sung-Eun; Um, Ji-Yong; Chae, Min-Kyun; Bang, Jihoon; Song, Jongkeun; Jeon, Taeho; Kim, Byungsub; Sim, Jae-Yoon; Park, Hong-June

    2017-02-01

    A 64-channel RX digital beamformer was implemented in a single chip for 3-D ultrasound medical imaging using 2-D phased-array transducers. The RX beamformer chip includes 64 analog front-end branches including 64 non-uniform sampling ADCs, a FIFO/Adder, and an on-chip look-up table (LUT). The LUT stores the information on the rising edge timing of the non-uniform ADC sampling clocks. To include the LUT inside the beamformer chip, the LUT size was reduced by around 240 times by approximating an ADC-sample-time profile w.r.t. focal points (FP) along a scanline (SL) for a channel into a piece-wise linear form. The maximum error between the approximated and accurate sample times of ADC is eight times the sample time resolution (Ts) that is 1/32 of the ultrasound signal period in this work. The non-uniform sampling reduces the FIFO size required for digital beamforming by around 20 times. By applying a 9-dot image from Field-II program and 2-D ultrasound phantom images to the fabricated RX beamformer chip, the original images were successfully reconstructed from the measured output. The chip in a 0.13-um CMOS occupies 30.25 [Formula: see text] and consumes 605 mW.

  17. Implementing OpenShift

    CERN Document Server

    Miller, Adam

    2013-01-01

    A standard tutorial-based approach to using OpenShift and deploying custom or pre-built web applications to the OpenShift Online cloud.This book is for software developers and DevOps alike who are interested in learning how to use the OpenShift Platform-as-a-Service for developing and deploying applications, how the environment works on the back end, and how to deploy their very own open source Platform-as-a-Service based on the upstream OpenShift Origin project.

  18. Stable and efficient retrospective 4D-MRI using non-uniformly distributed quasi-random numbers

    Science.gov (United States)

    Breuer, Kathrin; Meyer, Cord B.; Breuer, Felix A.; Richter, Anne; Exner, Florian; Weng, Andreas M.; Ströhle, Serge; Polat, Bülent; Jakob, Peter M.; Sauer, Otto A.; Flentje, Michael; Weick, Stefan

    2018-04-01

    The purpose of this work is the development of a robust and reliable three-dimensional (3D) Cartesian imaging technique for fast and flexible retrospective 4D abdominal MRI during free breathing. To this end, a non-uniform quasi random (NU-QR) reordering of the phase encoding (k y –k z ) lines was incorporated into 3D Cartesian acquisition. The proposed sampling scheme allocates more phase encoding points near the k-space origin while reducing the sampling density in the outer part of the k-space. Respiratory self-gating in combination with SPIRiT-reconstruction is used for the reconstruction of abdominal data sets in different respiratory phases (4D-MRI). Six volunteers and three patients were examined at 1.5 T during free breathing. Additionally, data sets with conventional two-dimensional (2D) linear and 2D quasi random phase encoding order were acquired for the volunteers for comparison. A quantitative evaluation of image quality versus scan times (from 70 s to 626 s) for the given sampling schemes was obtained by calculating the normalized mutual information (NMI) for all volunteers. Motion estimation was accomplished by calculating the maximum derivative of a signal intensity profile of a transition (e.g. tumor or diaphragm). The 2D non-uniform quasi-random distribution of phase encoding lines in Cartesian 3D MRI yields more efficient undersampling patterns for parallel imaging compared to conventional uniform quasi-random and linear sampling. Median NMI values of NU-QR sampling are the highest for all scan times. Therefore, within the same scan time 4D imaging could be performed with improved image quality. The proposed method allows for the reconstruction of motion artifact reduced 4D data sets with isotropic spatial resolution of 2.1  ×  2.1  ×  2.1 mm3 in a short scan time, e.g. 10 respiratory phases in only 3 min. Cranio-caudal tumor displacements between 23 and 46 mm could be observed. NU-QR sampling enables for stable 4D

  19. Darwin-Lagrangian analysis for the interaction of a point charge and a magnet: considerations related to the controversy regarding the Aharonov-Bohm and Aharonov-Casher phase shifts

    International Nuclear Information System (INIS)

    Boyer, Timothy H

    2006-01-01

    The classical electromagnetic interaction of a point charge and a magnet is discussed by first calculating the interaction of a point charge with a simple model magnetic moment and then suggesting a multiparticle limit. The Darwin-Lagrangian is used to analyse the electromagnetic behaviour of the model magnetic moment (composed of two oppositely charged particles of different masses in an initially circular Coulomb orbit) interacting with a passing point charge. Considerations of force, energy, momentum and centre of energy are treated through second order in 1/c. The changing magnetic moment is found to put a force back on a passing charge; this force is of order 1/c 2 and depends upon the magnitude of the magnetic moment. The limit of a many-particle magnet arranged as a toroid is discussed. It is suggested that in the multiparticle limit, the electric fields of the passing charge are screened out of the body of the magnet while the magnetic fields of the passing charge penetrate into the body of the magnet. This is consistent with our understanding of the penetration of electromagnetic velocity fields into ohmic conductors. The proposed multiparticle limit is consistent with the conservation laws for energy and momentum, as well as constant motion of the centre of energy, and Newton's third law for the net Lorentz forces on the magnet and on the point charge. The work corresponds to a classical electromagnetic analysis of the interaction which is basic to understanding the controversy over the Aharonov-Bohm and Aharonov-Casher phase shifts and represents a refutation of the suggestions of Aharonov, Pearle and Vaidman

  20. Outer region scaling using the freestream velocity for nonuniform open channel flow over gravel

    Science.gov (United States)

    Stewart, Robert L.; Fox, James F.

    2017-06-01

    The theoretical basis for outer region scaling using the freestream velocity for nonuniform open channel flows over gravel is derived and tested for the first time. Owing to the gradual expansion of the flow within the nonuniform case presented, it is hypothesized that the flow can be defined as an equilibrium turbulent boundary layer using the asymptotic invariance principle. The hypothesis is supported using similarity analysis to derive a solution, followed by further testing with experimental datasets. For the latter, 38 newly collected experimental velocity profiles across three nonuniform flows over gravel in a hydraulic flume are tested as are 43 velocity profiles previously published in seven peer-reviewed journal papers that focused on fluid mechanics of nonuniform open channel over gravel. The findings support the nonuniform flows as equilibrium defined by the asymptotic invariance principle, which is reflective of the consistency of the turbulent structure's form and function within the expanding flow. However, roughness impacts the flow structure when comparing across the published experimental datasets. As a secondary objective, we show how previously published mixed scales can be used to assist with freestream velocity scaling of the velocity deficit and thus empirically account for the roughness effects that extend into the outer region of the flow. One broader finding of this study is providing the theoretical context to relax the use of the elusive friction velocity when scaling nonuniform flows in gravel bed rivers; and instead to apply the freestream velocity. A second broader finding highlighted by our results is that scaling of nonuniform flow in gravel bed rivers is still not fully resolved theoretically since mixed scaling relies to some degree on empiricism. As researchers resolve the form and function of macroturbulence in the outer region, we hope to see the closing of this research gap.