Science.gov

Sample records for quadratures

  1. Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

    DOEpatents

    Buchenauer, C. Jerald

    1984-01-01

    The quadrature phase angle .phi.(t) of a pair of quadrature signals S.sub.1 (t) and S.sub.2 (t) is digitally encoded on a real time basis by a quadrature digitizer for fractional .phi.(t) rotational excursions and by a quadrature up/down counter for full .phi.(t) rotations. The pair of quadrature signals are of the form S.sub.1 (t)=k(t) sin .phi.(t) and S.sub.2 (t)=k(t) cos .phi.(t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle .phi.(t).

  2. Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

    DOEpatents

    Buchenauer, C.J.

    1981-09-23

    The quadrature phase angle phi (t) of a pair of quadrature signals S/sub 1/(t) and S/sub 2/(t) is digitally encoded on a real time basis by a quadrature digitizer for fractional phi (t) rotational excursions and by a quadrature up/down counter for full phi (t) rotations. The pair of quadrature signals are of the form S/sub 1/(t) = k(t) sin phi (t) and S/sub 2/(t) = k(t) cos phi (t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle phi (t).

  3. Quadrature wavelength scanning interferometry.

    PubMed

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-07-10

    A novel method to double the measurement range of wavelength scanning interferometery (WSI) is described. In WSI the measured optical path difference (OPD) is affected by a sign ambiguity, that is, from an interference signal it is not possible to distinguish whether the OPD is positive or negative. The sign ambiguity can be resolved by measuring an interference signal in quadrature. A method to obtain a quadrature interference signal for WSI is described, and a theoretical analysis of the advantages is reported. Simulations of the advantages of the technique and of signal errors due to nonideal quadrature are discussed. The analysis and simulation are supported by experimental measurements to show the improved performances. PMID:27409307

  4. Quadrature, Interpolation and Observability

    NASA Technical Reports Server (NTRS)

    Hodges, Lucille McDaniel

    1997-01-01

    Methods of interpolation and quadrature have been used for over 300 years. Improvements in the techniques have been made by many, most notably by Gauss, whose technique applied to polynomials is referred to as Gaussian Quadrature. Stieltjes extended Gauss's method to certain non-polynomial functions as early as 1884. Conditions that guarantee the existence of quadrature formulas for certain collections of functions were studied by Tchebycheff, and his work was extended by others. Today, a class of functions which satisfies these conditions is called a Tchebycheff System. This thesis contains the definition of a Tchebycheff System, along with the theorems, proofs, and definitions necessary to guarantee the existence of quadrature formulas for such systems. Solutions of discretely observable linear control systems are of particular interest, and observability with respect to a given output function is defined. The output function is written as a linear combination of a collection of orthonormal functions. Orthonormal functions are defined, and their properties are discussed. The technique for evaluating the coefficients in the output function involves evaluating the definite integral of functions which can be shown to form a Tchebycheff system. Therefore, quadrature formulas for these integrals exist, and in many cases are known. The technique given is useful in cases where the method of direct calculation is unstable. The condition number of a matrix is defined and shown to be an indication of the the degree to which perturbations in data affect the accuracy of the solution. In special cases, the number of data points required for direct calculation is the same as the number required by the method presented in this thesis. But the method is shown to require more data points in other cases. A lower bound for the number of data points required is given.

  5. Digital quadrature phase detection

    DOEpatents

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  6. Digital quadrature phase detection

    DOEpatents

    Smith, James A.; Johnson, John A.

    1992-01-01

    A system for detecting the phase of a frequency of phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2.pi. when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2.pi. when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention.

  7. Optimized quadrature surface coil designs

    PubMed Central

    Kumar, Ananda; Bottomley, Paul A.

    2008-01-01

    Background Quadrature surface MRI/MRS detectors comprised of circular loop and figure-8 or butterfly-shaped coils offer improved signal-to-noise-ratios (SNR) compared to single surface coils, and reduced power and specific absorption rates (SAR) when used for MRI excitation. While the radius of the optimum loop coil for performing MRI at depth d in a sample is known, the optimum geometry for figure-8 and butterfly coils is not. Materials and methods The geometries of figure-8 and square butterfly detector coils that deliver the optimum SNR are determined numerically by the electromagnetic method of moments. Figure-8 and loop detectors are then combined to create SNR-optimized quadrature detectors whose theoretical and experimental SNR performance are compared with a novel quadrature detector comprised of a strip and a loop, and with two overlapped loops optimized for the same depth at 3 T. The quadrature detection efficiency and local SAR during transmission for the three quadrature configurations are analyzed and compared. Results The SNR-optimized figure-8 detector has loop radius r8 ∼ 0.6d, so r8/r0 ∼ 1.3 in an optimized quadrature detector at 3 T. The optimized butterfly coil has side length ∼ d and crossover angle of ≥ 150° at the center. Conclusions These new design rules for figure-8 and butterfly coils optimize their performance as linear and quadrature detectors. PMID:18057975

  8. Length Scales in Bayesian Automatic Adaptive Quadrature

    NASA Astrophysics Data System (ADS)

    Adam, Gh.; Adam, S.

    2016-02-01

    Two conceptual developments in the Bayesian automatic adaptive quadrature approach to the numerical solution of one-dimensional Riemann integrals [Gh. Adam, S. Adam, Springer LNCS 7125, 1-16 (2012)] are reported. First, it is shown that the numerical quadrature which avoids the overcomputing and minimizes the hidden floating point loss of precision asks for the consideration of three classes of integration domain lengths endowed with specific quadrature sums: microscopic (trapezoidal rule), mesoscopic (Simpson rule), and macroscopic (quadrature sums of high algebraic degrees of precision). Second, sensitive diagnostic tools for the Bayesian inference on macroscopic ranges, coming from the use of Clenshaw-Curtis quadrature, are derived.

  9. Error Analysis of Quadrature Rules. Classroom Notes

    ERIC Educational Resources Information Center

    Glaister, P.

    2004-01-01

    Approaches to the determination of the error in numerical quadrature rules are discussed and compared. This article considers the problem of the determination of errors in numerical quadrature rules, taking Simpson's rule as the principal example. It suggests an approach based on truncation error analysis of numerical schemes for differential…

  10. Gaussian quadrature for multiple orthogonal polynomials

    NASA Astrophysics Data System (ADS)

    Coussement, Jonathan; van Assche, Walter

    2005-06-01

    We study multiple orthogonal polynomials of type I and type II, which have orthogonality conditions with respect to r measures. These polynomials are connected by their recurrence relation of order r+1. First we show a relation with the eigenvalue problem of a banded lower Hessenberg matrix Ln, containing the recurrence coefficients. As a consequence, we easily find that the multiple orthogonal polynomials of type I and type II satisfy a generalized Christoffel-Darboux identity. Furthermore, we explain the notion of multiple Gaussian quadrature (for proper multi-indices), which is an extension of the theory of Gaussian quadrature for orthogonal polynomials and was introduced by Borges. In particular, we show that the quadrature points and quadrature weights can be expressed in terms of the eigenvalue problem of Ln.

  11. Calculates Angular Quadrature Weights and Cosines.

    1988-02-18

    DSNQUAD calculates the angular quadrature weights and cosines for use in CCC-254/ANISN-ORNL. The subroutines in DSNQUAD were lifted from the XSDRN-PM code, which is supplied with the CCC-475/ SCALIAS-77 package.

  12. Angular quadratures for improved transport computations

    SciTech Connect

    Abu-Shumays, I.K.

    1999-07-22

    This paper introduces new octant-range, composite-type Gauss and mid-point rule angular quadrature formulas for neutron and photon transport computations. A generalization to octant-range quadratures is also introduced in order to allow for discontinuities at material interfaces for two- and three-dimensional transport problems which can be modeled with 60-degree triangular or hexagonal mesh subdivisions in the x-y plane.

  13. Past and Future SOHO-Ulysses Quadratures

    NASA Technical Reports Server (NTRS)

    Suess, Steven; Poletto, G.

    2006-01-01

    With the launch of SOHO, it again became possible to carry out quadrature observations. In comparison with earlier observations, the new capabilities of coronal spectroscopy with UVCS and in situ ionization state and composition with Ulysses/SWICS enabled new types of studies. Results from two studies serve as examples: (i) The acceleration profile of wind from small coronal holes. (ii) A high-coronal reconnecting current sheet as the source of high ionization state Fe in a CME at Ulysses. Generally quadrature observations last only for a few days, when Ulysses is within ca. 5 degrees of the limb. This means luck is required for the phenomenon of interest to lie along the radial direction to Ulysses. However, when Ulysses is at high southern latitude in winter 2007 and high northern latitude in winter 2008, there will be unusually favorable configurations for quadrature observations with SOHO and corresponding bracketing limb observations from STEREO A/B. Specifically, Ulysses will be within 5 degrees of the limb from December 2006 to May 2007 and within 10 degrees of the limb from December 2007 to May 2008. These long-lasting quadratures and bracketing STEREO A/B observations overcome the limitations inherent in the short observation intervals of typical quadratures. Furthermore, ionization and charge state measurements like those on Ulysses will also be made on STEREO and these will be essential for identification of CME ejecta - one of the prime objectives for STEREO.

  14. Quadrature formulae for problems in mechanics

    NASA Astrophysics Data System (ADS)

    Milovanović, Gradimir V.; Igić, Tomislav; Tončev, Novica

    2012-09-01

    The fast progress in recent years in symbolic computation and variable-precision arithmetic provide a possibility for generating the recursion coefficients in the three-term recurrence relation for orthogonal polynomials with respect to several nonclassical weight functions, as well as the construction of the corresponding quadrature rules of Gaussian type. Such quadratures are very important in many applications in engineering (fracture mechanics, damage mechanics, etc.), as well as in other computational and applied sciences. The boundary element method (BEM), finite element method (FEM), methods for solving integral equations, etc. very often require the numerical evaluation of one dimensional or multiple integrals with singular or near singular integrands with a high precision. In this paper we give some improvements of quadrature rules of Gaussian type with logarithmic and/or algebraic singularities. A numerical examples is included.

  15. Summation Paths in Clenshaw-Curtis Quadrature

    NASA Astrophysics Data System (ADS)

    Adam, S.; Adam, Gh.

    2016-02-01

    Two topics concerning the use of Clenshaw-Curtis quadrature within the Bayesian automatic adaptive quadrature approach to the numerical solution of Riemann integrals are considered. First, it is found that the efficient floating point computation of the coefficients of the Chebyshev series expansion of the integrand is to be done within a mathematical structure consisting of the union of coefficient families ordered into complete binary trees. Second, the scrutiny of the decay rates of the involved even and odd rank Chebyshev expansion coefficients with the increase of their rank labels enables the definition of Bayesian decision paths for the advancement to the numerical output.

  16. Composite Gauss-Legendre Quadrature with Error Control

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2011-01-01

    We describe composite Gauss-Legendre quadrature for determining definite integrals, including a means of controlling the approximation error. We compare the form and performance of the algorithm with standard Newton-Cotes quadrature. (Contains 1 table.)

  17. Error Bounds for Quadrature Methods Involving Lower Order Derivatives

    ERIC Educational Resources Information Center

    Engelbrecht, Johann; Fedotov, Igor; Fedotova, Tanya; Harding, Ansie

    2003-01-01

    Quadrature methods for approximating the definite integral of a function f(t) over an interval [a,b] are in common use. Examples of such methods are the Newton-Cotes formulas (midpoint, trapezoidal and Simpson methods etc.) and the Gauss-Legendre quadrature rules, to name two types of quadrature. Error bounds for these approximations involve…

  18. Uniform positive-weight quadratures for discrete ordinate transport calculations

    SciTech Connect

    Carew, J.F.; Zamonsky, G.

    1999-02-01

    Mechanical quadratures that allow systematic improvement and solution convergence are derived for application of the discrete ordinates method to the Boltzmann transport equation. the quadrature directions are arranged on n latitudinal levels, are uniformly distributed over the unit sphere, and have positive weights. Both a uniform and equal-weight quadrature set UE{sub n} and a uniform and Gauss-weight quadrature set UG{sub n} are derived. These quadratures have the advantage over the standard level-symmetric LQ{sub n} quadrature sets in that the weights are positive for all orders, and the solution may be systematically converged by increasing the order of the quadrature set. As the order of the quadrature is increased the points approach a uniform continuous distribution on the unit sphere and the quadrature is invariant with respect to spatial rotations. The numerical integrals converge for continuous functions as the order of the quadrature is increased. Numerical calculations were performed to evaluate the application of the UE{sub n} quadrature set. Comparisons of the exact moments and those calculated using the UE{sub n} quadrature set demonstrate that the moment integrals are performed accurately except for distributions that are very sharply peaked along the direction of the polar axis. A series of DORT transport calculations of the >1-Mev neutron flux for a typical reactor core/pressure vessel geometry were also carried out. These calculations employed the UE{sub n} (n = 6, 10, 12, 18, and 24) quadratures and indicate that the UE{sub n} solutions have converged to within {approximately}0.5%. The UE{sub 24} solutions were also found to be more accurate than the calculations performed with the S{sub 16} level-symmetric quadratures.

  19. Multisite EPR Oximetry from Multiple Quadrature Harmonics

    PubMed Central

    Ahmad, R.; Som, S.; Johnson, D.H.; Zweier, J.L.; Kuppusamy, P.; Potter, L.C.

    2011-01-01

    Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3 fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. PMID:22154283

  20. Optically controlled quadrature coupler on silicon substrate

    NASA Astrophysics Data System (ADS)

    Bhadauria, Avanish; Sharma, Sonia; Sonania, Shikha; Akhtar, Jamil

    2016-03-01

    In this paper, we have proposed and studied an optically controlled quadrature coupler fabricated on silicon substrate. The optically controlled quadrature coupler can be realized by terminating its coupled or through ports by optically induced load. Simulation and experimental results show that by varying optical intensity, we can control the phase and amplitude of output RF signal and can realize optically controlled reflection type attenuator, reflection type phase-shifter and ultrafast switches. The new kind of proposed device can be useful for ultra-fast signal processing and modulation schemes in high speed communication especially in QPSK modulation. The optical control has several advantages over conventional techniques such as MEMS and other semiconductor switching, which have several inherent disadvantages and limitations like low response time, low power handling capacity, device parasitic and non-linearity.

  1. Comparison of two Galerkin quadrature methods

    SciTech Connect

    Morel, J. E.; Warsa, J. S.; Franke, B. C.; Prinja, A. K.

    2013-07-01

    We compare two methods for generating Galerkin quadrature for problems with highly forward-peaked scattering. In Method 1, the standard Sn method is used to generate the moment-to-discrete matrix and the discrete-to-moment is generated by inverting the moment-to-discrete matrix. In Method 2, which we introduce here, the standard Sn method is used to generate the discrete-to-moment matrix and the moment-to-discrete matrix is generated by inverting the discrete-to-moment matrix. Method 1 has the advantage that it preserves both N eigenvalues and N eigenvectors (in a pointwise sense) of the scattering operator with an N-point quadrature. Method 2 has the advantage that it generates consistent angular moment equations from the corresponding S{sub N} equations while preserving N eigenvalues of the scattering operator with an N-point quadrature. Our computational results indicate that these two methods are quite comparable for the test problem considered. (authors)

  2. A brief survey of extrapolation quadrature.

    SciTech Connect

    Lyness, J. N.; Mathematics and Computer Science

    2000-07-01

    This is a short precis of a presentation on some of the recent advances in the area of extrapolation quadrature given at David Elliott's 65th birthday conference in Hobart in February 1997. Since the dawn of mathematics, historians and others have found many isolated instances of extrapolation being used in numerical calculation. However, the first serious proponent seems to have been Richardson (1923). His technique, also known as the 'deferred approach to the limit,' can be applied to the numerical evaluation of any quantity L, which can be defined as a limit as h approaches zero of an approximation L(h) when this L(h) has an expansion of the form L(h) = L + a{sub 1}h + a{sub 2}h{sup 2} + {hor_ellipsis} + a{sub r}h{sup r} + O(h{sup r+1}). In other words, the discretization error L(h) - L has a power series expansion in the parameter (usually a step length) h. Richardson suggested his technique particularly for large calculations. Richardson's technique comprised evaluating several relatively poor approximations based on different moderate values of h, and then extrapolating these values to obtain an approximately for L(0). This was proposed as an alternative to using a single, much smaller, value of h. During the subsequent 25 years, Richardson's approach was consistently ignored or misunderstood in environments where the analysis was available and, where in retrospect, the method would have been powerful, But, in the second half of the twentieth century, Richardson's idea has been widely exploited in several numerical areas. Many expansions that can be used for extrapolation have been discovered, some of which are displayed here. In the discipline of numerical quadrature, this body of theory is sometimes referred to as extrapolation quadrature. This theory has several aspects. The first, dealt with in this talk, is the establishment of the expansion. But also of significant importance are equations relating to is use: in particular, selecting which values of h

  3. The May 1997 SOHO-Ulysses Quadrature

    NASA Technical Reports Server (NTRS)

    Suess, Steven T.; Poletto, G.; Romoli, M.; Neugebauer, M.; Goldstein, B. E.; Simnett, G.

    2000-01-01

    We present results from the May 1997 SOHO-Ulysses quadrature, near sunspot minimum. Ulysses was at 5.1 AU, 100 north of the solar equator, and off the east limb. It was, by chance, also at the very northern edge of the streamer belt. Nevertheless, SWOOPS detected only slow, relatively smooth wind and there was no direct evidence of fast wind from the northern polar coronal hole or of mixing with fast wind. LASCO images show that the streamer belt at 10 N was narrow and sharp at the beginning and end of the two week observation interval, but broadened in the middle. A corresponding change in density, but not flow speed, occurred at Ulysses. Coronal densities derived from UVCS show that physical parameters in the lower corona are closely related to those in the solar wind, both over quiet intervals and in transient events on the limb. One small transient observed by both LASCO and UVCS is analyzed in detail.

  4. Power flow control using quadrature boosters

    NASA Astrophysics Data System (ADS)

    Sadanandan, Sandeep N.

    A power system that can be controlled within security constraints would be an advantage to power planners and real-time operators. Controlling flows can lessen reliability issues such as thermal limit violations, power stability problems, and/or voltage stability conditions. Control of flows can also mitigate market issues by reducing congestion on some lines and rerouting power to less loaded lines or onto preferable paths. In the traditional control of power flows, phase shifters are often used. More advanced methods include using Flexible AC Transmission System (FACTS) Controllers. Some examples include Thyristor Controlled Series Capacitors, Synchronous Series Static Compensators, and Unified Power Flow Controllers. Quadrature Boosters (QBs) have similar structures to phase-shifters, but allow for higher voltage magnitude during real power flow control. In comparison with other FACTS controllers QBs are not as complex and not as expensive. The present study proposes to use QBs to control power flows on a power system. With the inclusion of QBs, real power flows can be controlled to desired scheduled values. In this thesis, the linearized power flow equations used for power flow analysis were modified for the control problem. This included modifying the Jacobian matrix, the power error vector, and calculating the voltage injected by the quadrature booster for the scheduled real power flow. Two scenarios were examined using the proposed power flow control method. First, the power flow in a line in a 5-bus system was modified with a QB using the method developed in this thesis. Simulation was carried out using Matlab. Second, the method was applied to a 30-bus system and then to a 118-bus system using several QBs. In all the cases, the calculated values of the QB voltages led to desired power flows in the designated line.

  5. A Comparison of three high-precision quadrature schemes

    SciTech Connect

    Bailey, David H.; Li, Xiaoye S.

    2003-07-01

    The authors have implemented three numerical quadrature schemes, using the new Arbitrary Precision (ARPREC) software package, with the objective of seeking a completely ''automatic'' arbitrary precision quadrature facility, namely one that does not rely on a priori information of the function to be integrated. Such a facility is required, for example, to permit the experimental identification of definite integrals based on their numerical values. The performance and accuracy of these three quadrature schemes are compared using a suite of 15 integrals, ranging from continuous, well-behaved functions on finite intervals to functions with vertical derivatives and integrable singularities at endpoints, as well as several integrals on an infinite interval.

  6. Two integrator loop quadrature oscillators: A review

    PubMed Central

    Soliman, Ahmed M.

    2012-01-01

    A review of the two integrator loop oscillator circuits providing two quadrature sinusoidal output voltages is given. All the circuits considered employ the minimum number of capacitors namely two except one circuit which uses three capacitors. The circuits considered are classified to four different classes. The first class includes floating capacitors and floating resistors and the active building blocks realizing these circuits are the Op Amp or the OTRA. The second class employs grounded capacitors and includes floating resistors and the active building blocks realizing these circuits are the DCVC or the unity gain cells or the CFOA. The third class employs grounded capacitors and grounded resistors and the active building blocks realizing these circuits are the CCII. The fourth class employs grounded capacitors and no resistors and the active building blocks realizing these circuits are the TA. Transformation methods showing the generation of different classes from each other is given in details and this is one of the main objectives of this paper. PMID:25685396

  7. Algorithm 699 - A new representation of Patterson's quadrature formulae

    NASA Technical Reports Server (NTRS)

    Krogh, Fred T.; Van Snyder, W.

    1991-01-01

    A method is presented to reduce the number of coefficients necessary to represent Patterson's quadrature formulae. It also reduces the amount of storage necessary for storing function values, and produces slightly smaller error in evaluating the formulae.

  8. Experimental study of quadrature spring rate at tuned dry gyro

    NASA Astrophysics Data System (ADS)

    Hayakawa, Yoshiaki; Murayama, Naoshi

    A survey result on the mechanism of quadrature spring rate occurring at the tuned dry gyro is given. It is noted that the quadrature spring rate is a damping torque. This damping torque is similar to the spring reaction torque generated by the flexure displacement angles and drives the gyro rotor back to a balanced position. In order to investigate the mechanism of damping occurring at the gyro rotor, the relation between surrounding gas pressure and damping factor under gyro nonoperating was measured. Furthermore, the drag torque acting on the gyro rotor was measured by the back EMF method at different surrounding gas pressure. As a result of these testings, it was found out that the quadrature spring rate was generated by gas movement of the flexure around and drag forces due to bearing loss and windage loss, and the mechanism and magnitude of each damping torque which are contributor to the quadrature spring rate were extracted separately.

  9. Quadrature mixture LO suppression via DSW DAC noise dither

    DOEpatents

    Dubbert, Dale F.; Dudley, Peter A.

    2007-08-21

    A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage. A calibration technique can be employed to calculate both the quadrature correction vectors and the LO-nulling DC offsets using the radar built-in test capability.

  10. The Fall 2000 and Fall 2001 SOHO-Ulysses Quadratures

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.

    2000-01-01

    SOHO-Ulysses quadrature occurs when the SOHO-Sun-Ulysses included angle is 90 degrees. It is only at such times that the same plasma leaving the Sun in the direction of Ulysses can first be remotely analyzed with SOHO instruments and then later be sampled in situ by Ulysses instruments. The quadratures in December 2000 and 2001 are of special significance because Ulysses will be near the south and north heliographic poles, respectively, and the solar cycle will be near sunspot maximum. Quadrature geometry is sometimes confusing and observations are influenced by solar rotation. The Fall 2000 and 2001 quadratures are more complex than usual because Ulysses is not in a true polar orbit and the orbital speed of Ulysses about the Sun is becoming comparable to the speed of SOHO about the Sun. In 2000 Ulysses will always be slightly behind the pole but will appear to hang over the pole for over two months because it is moving around the Sun in the same direction as SOHO. In 20001, Ulysses will be slightly in front of the pole so that its footpoint will be directly observable. Detailed plots will be shown of the relative positions of SOHO and Ulysses will their relative positions. In neither case is true quadrature actually achieved, but this works to the observers advantage in 2001.

  11. The Fall 2000 and Fall 2001 SOHO-Ulysses Quadratures

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    SOHO-Ulysses quadrature occurs when the SOHO-Sun-Ulysses included angle is 90 degrees. It is only at such times that the same plasma leaving the Sun in the direction of Ulysses can first be remotely analyzed with SOHO instruments and then later be sampled in situ by Ulysses instruments. The quadratures in December 2000 and 2001 are of special significance because Ulysses will be near the south and north heliographic poles, respectively, and the solar cycle will be near sunspot maximum. Quadrature geometry is sometimes confusing and observations are influenced by solar rotation. The Fall 2000 and 2001 quadratures are more complex than usual because Ulysses is not in a true polar orbit and the orbital speed of Ulysses about the Sun is becoming comparable to the speed of SOHO about the Sun. In 2000 Ulysses will always be slightly behind the pole but will appear to hang over the pole for over two months because it is moving around the Sun in the same direction as SOHO. In 2001 Ulysses will be slightly in front of the pole so that its footpoint will be directly observable. Detailed plots will be shown of the relative positions of SOHO and Ulysses will their relative positions. In neither case is true quadrature actually achieved, but this works to the observers advantage in 2001.

  12. Kinetic Plasma Simulation Using a Quadrature-based Moment Method

    NASA Astrophysics Data System (ADS)

    Larson, David J.

    2008-11-01

    The recently developed quadrature-based moment method [Desjardins, Fox, and Villedieu, J. Comp. Phys. 227 (2008)] is an interesting alternative to standard Lagrangian particle simulations. The two-node quadrature formulation allows multiple flow velocities within a cell, thus correctly representing crossing particle trajectories and lower-order velocity moments without resorting to Lagrangian methods. Instead of following many particles per cell, the Eulerian transport equations are solved for selected moments of the kinetic equation. The moments are then inverted to obtain a discrete representation of the velocity distribution function. Potential advantages include reduced computational cost, elimination of statistical noise, and a simpler treatment of collisional effects. We present results obtained using the quadrature-based moment method applied to the Vlasov equation in simple one-dimensional electrostatic plasma simulations. In addition we explore the use of the moment inversion process in modeling collisional processes within the Complex Particle Kinetics framework.

  13. Discrete Ordinate Quadrature Selection for Reactor-based Eigenvalue Problems

    SciTech Connect

    Jarrell, Joshua J; Evans, Thomas M; Davidson, Gregory G

    2013-01-01

    In this paper we analyze the effect of various quadrature sets on the eigenvalues of several reactor-based problems, including a two-dimensional (2D) fuel pin, a 2D lattice of fuel pins, and a three-dimensional (3D) reactor core problem. While many quadrature sets have been applied to neutral particle discrete ordinate transport calculations, the Level Symmetric (LS) and the Gauss-Chebyshev product (GC) sets are the most widely used in production-level reactor simulations. Other quadrature sets, such as Quadruple Range (QR) sets, have been shown to be more accurate in shielding applications. In this paper, we compare the LS, GC, QR, and the recently developed linear-discontinuous finite element (LDFE) sets, as well as give a brief overview of other proposed quadrature sets. We show that, for a given number of angles, the QR sets are more accurate than the LS and GC in all types of reactor problems analyzed (2D and 3D). We also show that the LDFE sets are more accurate than the LS and GC sets for these problems. We conclude that, for problems where tens to hundreds of quadrature points (directions) per octant are appropriate, QR sets should regularly be used because they have similar integration properties as the LS and GC sets, have no noticeable impact on the speed of convergence of the solution when compared with other quadrature sets, and yield more accurate results. We note that, for very high-order scattering problems, the QR sets exactly integrate fewer angular flux moments over the unit sphere than the GC sets. The effects of those inexact integrations have yet to be analyzed. We also note that the LDFE sets only exactly integrate the zeroth and first angular flux moments. Pin power comparisons and analyses are not included in this paper and are left for future work.

  14. Offset quadrature communications with decision-feedback carrier synchronization

    NASA Technical Reports Server (NTRS)

    Simon, M. K.; Smith, J. G.

    1974-01-01

    In order to accommodate a quadrature amplitude-shift-keyed (QASK) signal, Simon and Smith (1974) have modified the decision-feedback loop which tracks a quadrature phase-shift-keyed (QPSK). In the investigation reported approaches are considered to modify the loops in such a way that offset QASK signals can be tracked, giving attention to the special case of an offset QPSK. The development of the stochastic integro-differential equation of operation for a decision-feedback offset QASK loop is discussed along with the probability density function of the phase error process.

  15. Vibration analysis of structural elements using differential quadrature method.

    PubMed

    Nassar, Mohamed; Matbuly, Mohamed S; Ragb, Ola

    2013-01-01

    The method of differential quadrature is employed to analyze the free vibration of a cracked cantilever beam resting on elastic foundation. The beam is made of a functionally graded material and rests on a Winkler-Pasternak foundation. The crack action is simulated by a line spring model. Also, the differential quadrature method with a geometric mapping are applied to study the free vibration of irregular plates. The obtained results agreed with the previous studies in the literature. Further, a parametric study is introduced to investigate the effects of geometric and elastic characteristics of the problem on the natural frequencies.

  16. Applying Quadrature Rules with Multiple Nodes to Solving Integral Equations

    SciTech Connect

    Hashemiparast, S. M.; Avazpour, L.

    2008-09-01

    There are many procedures for the numerical solution of Fredholm integral equations. The main idea in these procedures is accuracy of the solution. In this paper, we use Gaussian quadrature with multiple nodes to improve the solution of these integral equations. The application of this method is illustrated via some examples, the related tables are given at the end.

  17. Archimedes Quadrature of the Parabola: A Mechanical View

    ERIC Educational Resources Information Center

    Oster, Thomas J.

    2006-01-01

    In his famous quadrature of the parabola, Archimedes found the area of the region bounded by a parabola and a chord. His method was to fill the region with infinitely many triangles each of whose area he could calculate. In his solution, he stated, without proof, three preliminary propositions about parabolas that were known in his time, but are…

  18. Trapezoidal rule quadrature algorithms for MIMD distributed memory computers

    SciTech Connect

    Lyness, J.N.; Plowman, S.E.

    1994-08-01

    An approach to multi-dimensional quadrature, designed to exploit parallel architectures, is described. This involves transforming the integral in such a way that an accurate result is given by the trapezoidal rule; and by evaluating the resulting sum in a manner which may be efficiently implemented on parallel architectures. This approach is to be implemented in the Liverpool NAG transputer library.

  19. Wave-Based Inversion & Imaging for the Optical Quadrature Microscope

    SciTech Connect

    Lehman, S K

    2005-10-27

    The Center for Subsurface Sensing & Imaging System's (CenSSIS) Optical Quadrature Microscope (OQM) is a narrow band visible light microscope capable of measuring both amplitude and phase of a scattered field. We develop a diffraction tomography, that is, wave-based, scattered field inversion and imaging algorithm, for reconstructing the refractive index of the scattering object.

  20. From Lobatto Quadrature to the Euler Constant "e"

    ERIC Educational Resources Information Center

    Khattri, Sanjay Kumar

    2010-01-01

    Based on the Lobatto quadrature, we develop several new closed form approximations to the mathematical constant "e." For validating effectiveness of our approximations, a comparison of our results to the existing approximations is also presented. Another objective of our work is to inspire students to formulate other better approximations by using…

  1. Giant violations of classical inequalities through conditional homodyne detection of the quadrature amplitudes of light

    PubMed

    Carmichael; Castro-Beltran; Foster; Orozco

    2000-08-28

    Conditional homodyne detection is proposed as an extension of the intensity correlation technique introduced by Hanbury-Brown and Twiss [Nature (London) 177, 27 (1956)]. It detects giant quadrature amplitude fluctuations for weakly squeezed light, violating a classical bound by orders of magnitude. Fluctuations of both quadrature amplitudes are anomalously large. The squeezed quadrature also exhibits an anomalous phase. PMID:10970631

  2. Coherent detection of frequency-hopped quadrature modulations in the presence of jamming. II - QPR Class I modulation. [Quadrature Partial Response

    NASA Technical Reports Server (NTRS)

    Simon, M. K.

    1981-01-01

    This paper considers the performance of quadrature partial response (QPR) in the presence of jamming. Although a QPR system employs a single sample detector in its receiver, while quadrature amplitude shift keying (or quadrature phase shift keying) requires a matched-filter type of receiver, it is shown that the coherent detection performances of the two in the presence of the intentional jammer have definite similarities.

  3. Extraction of quadrature phase information from multiple pulse NMR signals

    NASA Technical Reports Server (NTRS)

    Rhim, W.-K.; Burum, D. P.; Vaughan, R. W.

    1976-01-01

    A multiple pulse sequence (8-pulse sequence) used for high-resolution solid state NMR is analyzed with regard to the information available from each of the four wide sampling windows. It is demonstrated that full quadrature phase information can be obtained using only a single phase detector and that, for the commonly encountered situation where the spectral width is much less than the folding frequency, the signals from the various windows can be combined easily using standard complex Fourier transform software. An improvement in the signal-to-noise ratio equal to the square root of 3 is obtained over either standard single or quadrature phase detection schemes. Procedures for correcting spectral distortions are presented.

  4. MQD--multiplex-quadrature detection in multi-dimensional NMR.

    PubMed

    Schlagnitweit, Judith; Horničáková, Michaela; Zuckerstätter, Gerhard; Müller, Norbert

    2012-01-16

    With multiplex-quadrature detection (MQD) the tasks of coherence selection and quadrature separation in N-dimensional heteronuclear NMR experiments are merged. Thus the number of acquisitions required to achieve a desired resolution in the indirect dimensions is significantly reduced. The minimum number of transients per indirect data point, which have to be combined to give pure-phase spectra, is thus decreased by a factor (3/4)(N-1). This reduction is achieved without adjustable parameters. We demonstrate the advantage by MQD 3D HNCO and HCCH-TOCSY spectra affording the same resolution and the same per-scan sensitivity as standard phase-cycled ones, but obtained in only 56 % of the usual time and by resolution improvements achieved in the same amount of time. PMID:22095747

  5. Solar Wind Characteristics from SOHO-Sun-Ulysses Quadrature Observations

    NASA Technical Reports Server (NTRS)

    Poletto, Giannina; Suess, Steve T.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Over the past few years, we have been running SOHO (Solar and Heliospheric Observatory)-Sun-Ulysses quadrature campaigns, aimed at comparing the plasma properties at coronal altitudes with plasma properties at interplanetary distances. Coronal plasma has been observed by SOHO experiments: mainly, we used LASCO (Large Angle and Spectrometric Coronagraph Experiment) data to understand the overall coronal configuration at the time of quadratures and analyzed SUMER (Solar Ultraviolet Measurements of Emitted Radiation), CDS (Coronal Diagnostic Spectrometer) and UVCS (Ultraviolet Coronagraph Spectrometer) data to derive its physical characteristics. At interplanetary distances, SWICS (Solar Wind Ion Composition Spectrometer) and SWOOPS (Solar Wind Observation over the Poles of the Sun) aboard Ulysses provided us with interplanetary plasma data. Here we report on results from some of the campaigns. We notice that, depending on the geometry of the quadrature, i.e. on whether the radial to Ulysses traverses the corona at high or low latitudes, we are able to study different kinds of solar wind. In particular, a comparison between low-latitude and high-latitude wind, allowed us to provide evidence for differences in the acceleration of polar, fast plasma and equatorial, slow plasma: the latter occurring at higher levels and through a more extended region than fast wind. These properties are shared by both the proton and heavy ions outflows. Quadrature observations may provide useful information also on coronal vs. in situ elemental composition. To this end, we analyzed spectra taken in the corona, at altitudes ranging between approx. 1.02 and 2.2 solar radii, and derived the abundances of a number of ions, including oxygen and iron. Values of the O/Fe ratio, at coronal levels, have been compared with measurements of this ratio made by SWICS at interplanetary distances. Our results are compared with previous findings and predictions from modeling efforts.

  6. Optimized quantum nondemolition measurement of a field quadrature

    NASA Astrophysics Data System (ADS)

    Paris, Matteo G.

    2002-01-01

    We suggest an interferometric scheme assisted by squeezing and linear feedback to realize the whole class of field-quadrature quantum nondemolition measurements, from Von Neumann projective measurement to a fully nondestructive noninformative one. In our setup, the signal under investigation is mixed with a squeezed probe in an interferometer and, at the output, one of the two modes is revealed through homodyne detection. The second beam is then amplitude-modulated according to the outcome of the measurement, and finally squeezed according to the transmittivity of the interferometer. Using strongly squeezed or antisqueezed probes respectively, one achieves either a projective measurement, i.e., homodyne statistics arbitrarily close to the intrinsic quadrature distribution of the signal, and conditional outputs approaching the corresponding eigenstates, or a fully nondestructive one, characterized by an almost uniform homodyne statistics, and by an output state arbitrarily close to the input signal. By varying the squeezing between these two extremes, or simply by tuning the internal phase shift of the interferometer, the whole set of intermediate cases may also be obtained. In particular, an optimal quantum nondemolition measurement of quadrature may be achieved, which minimizes the information gain versus state disturbance tradeoff.

  7. Discrete ordinates with new quadrature sets and modified source conditions

    SciTech Connect

    Ganguly, K.; Allen, E.J., Victory, H.D. Jr. )

    1989-01-01

    A major shortcoming of the discrete ordinates method with the Gauss-Legendre quadrature set is that when the number of secondaries per primary c and the order of approximation N are not too large, all the (N + 1)v (the flux being of the form exp({minus}x/v)) lie in ({minus}1,1). It is known, however, that the largest v{sub j} corresponding to the asymptotic flux is greater than unity. The Legendre polynomial used for obtaining the quadrature set is orthogonal with respect to weight unity in the range ({minus}1,1). However, the Case and Zweifel eigenfunctions derived from the exact solution of one-speed transport theory are orthogonal with respect to a complicated weight function w({mu}) and {mu} in the half-range and full-range cases, respectively. In this paper, the authors have used a set of orthogonal polynomials with respect to w ({mu}) to develop quadrature sets to be used in the discrete ordinates calculation.

  8. Statistical Quadrature Evolution for Continuous-Variable Quantum Key Distribution

    NASA Astrophysics Data System (ADS)

    Gyongyosi, Laszlo; Imre, Sandor

    2016-05-01

    We propose a statistical quadrature evolution (SQE) method for multicarrier continuous-variable quantum key distribution (CVQKD). A multicarrier CVQKD protocol utilizes Gaussian subcarrier quantum continuous variables (CV) for information transmission. The SQE framework provides a minimal error estimate of the quadratures of the CV quantum states from the discrete, measured noisy subcarrier variables. We define a method for the statistical modeling and processing of noisy Gaussian subcarrier quadratures. We introduce the terms statistical secret key rate and statistical private classical information, which quantities are derived purely by the statistical functions of our method. We prove the secret key rate formulas for a multiple access multicarrier CVQKD. The framework can be established in an arbitrary CVQKD protocol and measurement setting, and are implementable by standard low-complexity statistical functions, which is particularly convenient for an experimental CVQKD scenario. This work was partially supported by the GOP-1.1.1-11-2012-0092 project sponsored by the EU and European Structural Fund, by the Hungarian Scientific Research Fund - OTKA K-112125, and by the COST Action MP1006.

  9. Quadrature two-dimensional correlation spectroscopy (Q-2DCOS)

    NASA Astrophysics Data System (ADS)

    Noda, Isao

    2016-11-01

    Quadrature 2D correlation spectroscopy (Q-2DCOS) is introduced. The technique incorporates the effect of the perturbation into the traditional 2DCOS analysis by building a multivariate model, merging the information of the perturbation variable and spectral responses. By employing factors which are 90° out of phase with each other, pertinent coincidental and sequential spectral intensity variations are adequately captured for the subsequent 2D correlation analysis. Almost complete replication of the original 2DCOS results based on such a simple rank 2 model of experimental spectra suggests that only the dominant spectral intensity variation patterns in combination with its quadrature counterpart seems to be utilized in 2DCOS analysis. Using the linear perturbation variable itself as the basis for generating the primary score vector is equivalent to the least squares fitting of a quadratic polynomial with spectral intensity variations. Q-2DCOS analysis may be displayed in terms of a graphical plot on a phase plane in the vector space, so that coincidental and sequential matching of the patterns of spectral intensity variations is represented simply by the phase angle difference between two vectors. Q-2DCOS analysis is closely related to other established ideas and practices in the 2D correlation spectroscopy field, such as dynamic 2D IR dichroism, PCA 2D, quadrature orthogonal signal correction (Q-OSC), and perturbation correlation moving window (PCMW) analyses.

  10. Testing the Empirical Shock Arrival Model Using Quadrature Observations

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Xie, H.; Yashiro, S.

    2013-01-01

    The empirical shock arrival (ESA) model was developed based on quadrature data from Helios (in situ) and P-78 (remote sensing) to predict the Sun-Earth travel time of coronal mass ejections (CMEs). The ESA model requires earthward CME speed as input, which is not directly measurable from coronagraphs along the Sun-Earth line. The Solar Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory (SOHO) were in quadrature during 20102012, so the speeds of Earth-directed CMEs were observed with minimal projection effects. We identified a set of 20 full halo CMEs in the field of view of SOHO that were also observed in quadrature by STEREO. We used the earthward speed from STEREO measurements as input to the ESA model and compared the resulting travel times with the observed ones from L1 monitors. We find that the model predicts the CME travel time within about 7.3 h, which is similar to the predictions by the ENLIL model. We also find that CME-CME and CME-coronal hole interaction can lead to large deviations from model predictions.

  11. Advanced quadratures and periodic boundary conditions in parallel 3D S{sub n} transport

    SciTech Connect

    Manalo, K.; Yi, C.; Huang, M.; Sjoden, G.

    2013-07-01

    Significant updates in numerical quadratures have warranted investigation with 3D Sn discrete ordinates transport. We show new applications of quadrature departing from level symmetric (S{sub 2}o). investigating 3 recently developed quadratures: Even-Odd (EO), Linear-Discontinuous Finite Element - Surface Area (LDFE-SA), and the non-symmetric Icosahedral Quadrature (IC). We discuss implementation changes to 3D Sn codes (applied to Hybrid MOC-Sn TITAN and 3D parallel PENTRAN) that can be performed to accommodate Icosahedral Quadrature, as this quadrature is not 90-degree rotation invariant. In particular, as demonstrated using PENTRAN, the properties of Icosahedral Quadrature are suitable for trivial application using periodic BCs versus that of reflective BCs. In addition to implementing periodic BCs for 3D Sn PENTRAN, we implemented a technique termed 'angular re-sweep' which properly conditions periodic BCs for outer eigenvalue iterative loop convergence. As demonstrated by two simple transport problems (3-group fixed source and 3-group reflected/periodic eigenvalue pin cell), we remark that all of the quadratures we investigated are generally superior to level symmetric quadrature, with Icosahedral Quadrature performing the most efficiently for problems tested. (authors)

  12. Noise-cancelling quadrature magnetic position, speed and direction sensor

    DOEpatents

    Preston, Mark A.; King, Robert D.

    1996-01-01

    An array of three magnetic sensors in a single package is employed with a single bias magnet for sensing shaft position, speed and direction of a motor in a high magnetic noise environment. Two of the three magnetic sensors are situated in an anti-phase relationship (i.e., 180.degree. out-of-phase) with respect to the relationship between the other of the two sensors and magnetically salient target, and the third magnetic sensor is situated between the anti-phase sensors. The result is quadrature sensing with noise immunity for accurate relative position, speed and direction measurements.

  13. M-link multiplexing over the quadrature communications channel

    NASA Astrophysics Data System (ADS)

    Gagliardi, R.

    1984-09-01

    The possibility of multiplexing more than two independent, unsynchronized data streams on a quadrature carrier channel is investigated theoretically. It is found that by using linear (or near linear) combinations of basis carriers, no increase in overall bandwidth occurs as more channels are added, increasing the overall system throughput. Symbol decoding with banks of independent bit integrators after phase coherent demodulation was investigated, and degradation and bit error probabilities were computed. The results indicate that significant degradations occur even with relatively few added channels, but bandwidth savings and the simple encoder and decoder circuitry may prove a cost-efficient tradeoff in bandwidth restricted systems.

  14. Solvability of a Lie algebra of vector fields implies their integrability by quadratures

    NASA Astrophysics Data System (ADS)

    Cariñena, J. F.; Falceto, F.; Grabowski, J.

    2016-10-01

    We present a substantial generalisation of a classical result by Lie on integrability by quadratures. Namely, we prove that all vector fields in a finite-dimensional transitive and solvable Lie algebra of vector fields on a manifold can be integrated by quadratures.

  15. The Nature of the Nodes, Weights and Degree of Precision in Gaussian Quadrature Rules

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2011-01-01

    We present a comprehensive proof of the theorem that relates the weights and nodes of a Gaussian quadrature rule to its degree of precision. This level of detail is often absent in modern texts on numerical analysis. We show that the degree of precision is maximal, and that the approximation error in Gaussian quadrature is minimal, in a…

  16. Quadrature phase interferometer for high resolution force spectroscopy

    SciTech Connect

    Paolino, Pierdomenico; Aguilar Sandoval, Felipe A.; Bellon, Ludovic

    2013-09-15

    In this article, we present a deflection measurement setup for Atomic Force Microscopy (AFM). It is based on a quadrature phase differential interferometer: we measure the optical path difference between a laser beam reflecting above the cantilever tip and a reference beam reflecting on the static base of the sensor. A design with very low environmental susceptibility and another allowing calibrated measurements on a wide spectral range are described. Both enable a very high resolution (down to 2.5×10{sup −15} m/√(Hz)), illustrated by thermal noise measurements on AFM cantilevers. They present an excellent long-term stability and a constant sensitivity independent of the optical phase of the interferometer. A quick review shows that our precision is equaling or out-performing the best results reported in the literature, but for a much larger deflection range, up to a few μm.

  17. Quadrature component analysis of interferograms with random phase shifts

    NASA Astrophysics Data System (ADS)

    Xu, Jiancheng; Chen, Zhao

    2014-08-01

    Quadrature component analysis (QCA) is an effective method for analyzing the interferograms if the phase shifts are uniformly distributed in the [0, 2π] range. However, it is hard to meet this requirement in practical applications, so a parameter named the non-orthogonal degree (NOD) is proposed to indicate the degree when the phase shifts are not well distributed. We analyze the relation between the parameter of NOD and the accuracy of the QCA algorithm by numerical simulation. By using the parameter of NOD, the relation between the distribution of the phase shift and the accuracy of the QCA algorithm is obtained. The relation is discussed and verified by numerical simulations and experiments.

  18. Terahertz single-shot quadrature phase-shifting interferometry.

    PubMed

    Földesy, Péter

    2012-10-01

    A single-shot quadrature phase-shifting interferometry architecture is presented that is applicable to antenna coupled detector technologies. The method is based on orthogonally polarized object and reference beams and on linear and circular polarization sensitive antennas in space-division multiplexing. The technique can be adapted to two-, three-, and four-step and Gabor holography recordings. It is also demonstrated that the space-division multiplexing does not necessarily cause sparse sampling. A sub-THz detector array is presented containing multiple on-chip antennas and FET plasma wave detectors implemented in a 90 nm complementary metal-oxide semiconductor technology. As an example, two-step phase-shifting reconstruction results are given at 360 GHz. PMID:23027273

  19. Quadrature formula for evaluating left bounded Hadamard type hypersingular integrals

    NASA Astrophysics Data System (ADS)

    Bichi, Sirajo Lawan; Eshkuvatov, Z. K.; Nik Long, N. M. A.; Okhunov, Abdurahim

    2014-12-01

    Left semi-bounded Hadamard type Hypersingular integral (HSI) of the form H(h,x) = 1/π √{1+x/1-x }∫-1 **1√{1-t/1+t }h(t)/(t-x)2 dt,x∈(-1.1), Where h(t) is a smooth function is considered. The automatic quadrature scheme (AQS) is constructed by approximating the density function h(t) by the truncated Chebyshev polynomials of the fourth kind. Numerical results revealed that the proposed AQS is highly accurate when h(t) is choosing to be the polynomial and rational functions. The results are in line with the theoretical findings.

  20. Harmonic Golay coded excitation based on harmonic quadrature demodulation method.

    PubMed

    Kim, Sang-Min; Song, Jae-Hee; Song, Tai-Kyong

    2008-01-01

    Harmonic coded excitation techniques have been used to increase SNR of harmonic imaging with limited peak voltage. Harmonic Golay coded excitation, in particular, generates each scan line using four transmit-receive cycles, unlike conventional Golay coded excitation method, thus resulting in low frame rates. In this paper we propose a method of increasing the frame rate of said method without impacting the image quality. The proposed method performs two transmit-receive cycles using QPSK code to ensure that the harmonic components of incoming signals are Golay coded and uses harmonic quadrature demodulation to extract compressed second harmonic component only. The proposed method has been validated through mathematical analysis and MATLAB simulation, and has been verified to yield a limited error of -52.08dB compared to the ideal case. Therefore, the proposed method doubles the frame rate compared to the existing harmonic Golay coded excitation method without significantly deteriorating the image quality.

  1. Residual Distribution Schemes for Conservation Laws Via Adaptive Quadrature

    NASA Technical Reports Server (NTRS)

    Barth, Timothy; Abgrall, Remi; Biegel, Bryan (Technical Monitor)

    2000-01-01

    This paper considers a family of nonconservative numerical discretizations for conservation laws which retains the correct weak solution behavior in the limit of mesh refinement whenever sufficient order numerical quadrature is used. Our analysis of 2-D discretizations in nonconservative form follows the 1-D analysis of Hou and Le Floch. For a specific family of nonconservative discretizations, it is shown under mild assumptions that the error arising from non-conservation is strictly smaller than the discretization error in the scheme. In the limit of mesh refinement under the same assumptions, solutions are shown to satisfy an entropy inequality. Using results from this analysis, a variant of the "N" (Narrow) residual distribution scheme of van der Weide and Deconinck is developed for first-order systems of conservation laws. The modified form of the N-scheme supplants the usual exact single-state mean-value linearization of flux divergence, typically used for the Euler equations of gasdynamics, by an equivalent integral form on simplex interiors. This integral form is then numerically approximated using an adaptive quadrature procedure. This renders the scheme nonconservative in the sense described earlier so that correct weak solutions are still obtained in the limit of mesh refinement. Consequently, we then show that the modified form of the N-scheme can be easily applied to general (non-simplicial) element shapes and general systems of first-order conservation laws equipped with an entropy inequality where exact mean-value linearization of the flux divergence is not readily obtained, e.g. magnetohydrodynamics, the Euler equations with certain forms of chemistry, etc. Numerical examples of subsonic, transonic and supersonic flows containing discontinuities together with multi-level mesh refinement are provided to verify the analysis.

  2. Adaptive quadrature-polybinary detection in super-Nyquist WDM systems.

    PubMed

    Chen, Sai; Xie, Chongjin; Zhang, Jie

    2015-03-23

    We propose an adaptive detection technique in super-Nyquist wavelength-division-multiplexed (WDM) polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) systems, where a QPSK signal is digitally converted to a quadrature n-level polybinary signal followed by a MLSE detector at the receiver, and study the performance of quadrature-duobinary and quadrature four-level polybinary signals using this detection technique. We change the level of the quadrature-polybinary modulation at the coherent receiver according to the channel spacing of a super-Nyquist system. Numerical studies show that the best performance can be achieved by choosing different modulation levels at the receiver in adaption to the channel spacing. In the experiment, we demonstrate the transmission of 3-channel 112-Gbit/s PDM-QPSK signals at a 20-GHz channel spacing, which is detected as a quadrature four-level polybinary signal, with performance comparable to PDM 16-ary quadrature-amplitude modulation (16QAM) at the same bit rate.

  3. Multidimensional Hermite-Gaussian quadrature formulae and their application to nonlinear estimation

    NASA Technical Reports Server (NTRS)

    Mcreynolds, S. R.

    1975-01-01

    A simplified technique is proposed for calculating multidimensional Hermite-Gaussian quadratures that involves taking the square root of a matrix by the Cholesky algorithm rather than computation of the eigenvectors of the matrix. Ways of reducing the dimension, number, and order of the quadratures are set forth. If the function f(x) under the integral sign is not well approximated by a low-order algebraic expression, the order of the quadrature may be reduced by factoring f(x) into an expression that is nearly algebraic and one that is Gaussian.

  4. Programs for computing abscissas and weights for classical and nonclassical Gaussian quadrature formulas

    NASA Technical Reports Server (NTRS)

    Desmarais, R. N.

    1975-01-01

    Computer programs for computing Gaussian quadrature abscissas and weights are described. For the classical case the programs use Laguerre iteration to compute abscissas as zeros of orthogonal polynomials. The polynomials are evaluated from known recursion coefficients. The nonclassical case is handled similarly except that the recursion coefficients are computed by numerical integration. A sample problem, with input and output, is presented to illustrate the use of the programs. It computes the quadrature abscissas and weights associated with the weight function over the interval (0,1) for quadrature orders from 16 to 96 in increments of 8.

  5. Quadrature methods for periodic singular and weakly singular Fredholm integral equations

    NASA Technical Reports Server (NTRS)

    Sidi, Avram; Israeli, Moshe

    1988-01-01

    High-accuracy numerical quadrature methods for integrals of singular periodic functions are proposed. These methods are based on the appropriate Euler-Maclaurin expansions of trapezoidal rule approximations and their extrapolations. They are subsequently used to obtain accurate quadrature methods for the solution of singular and weakly singular Fredholm integral equations. Throughout the development the periodic nature of the problem plays a crucial role. Such periodic equations are used in the solution of planar elliptic boundary value problems such as those that arise in elasticity, potential theory, conformal mapping, and free surface flows. The use of the quadrature methods is demonstrated with numerical examples.

  6. Modulator-free quadrature amplitude modulation signal synthesis

    PubMed Central

    Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O’Carroll, John; Phelan, Richard; Richardson, David J.; Slavík, Radan

    2014-01-01

    The ability to generate high-speed on–off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5 Gbit s−1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on–off-keyed 10 Gbit s−1 systems and is absolutely prohibitive for today’s (>)100 Gbit s−1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions. PMID:25523757

  7. A Quadrature Free Discontinuous Galerkin Conservative Level Set Scheme

    NASA Astrophysics Data System (ADS)

    Czajkowski, Mark; Desjardins, Olivier

    2010-11-01

    In an effort to improve the scalability and accuracy of the Accurate Conservative Level Set (ACLS) scheme [Desjardins et al., J COMPUT PHYS 227 (2008)], a scheme based on the quadrature free discontinuous Galerkin (DG) methodology has been developed. ACLS relies on a hyperbolic tangent level set function that is transported and reinitialized using conservative schemes in order to alleviate mass conservation issues known to plague level set methods. DG allows for an arbitrarily high order representation of the interface by using a basis of high order polynomials while only using data from the faces of neighboring cells. The small stencil allows DG to have excellent parallel scalability. The diffusion term present in the conservative reinitialization equation is handled using local DG method [Cockburn et al., SIAM J NUMER ANAL 39, (2001)] while the normals are computed from a limited form of the level set function in order to avoid spurious oscillations. The resulting scheme is shown to be both robust, accurate, and highly scalable, making it a method of choice for large-scale simulations of multiphase flows with complex interfacial topology.

  8. Modeling of optical quadrature microscopy for imaging mouse embryos

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; DiMarzio, Charles A.

    2008-02-01

    Optical quadrature microscopy (OQM) has been shown to provide the optical path difference through a mouse embryo, and has led to a novel method to count the total number of cells further into development than current non-toxic imaging techniques used in the clinic. The cell counting method has the potential to provide an additional quantitative viability marker for blastocyst transfer during in vitro fertilization. OQM uses a 633 nm laser within a modified Mach-Zehnder interferometer configuration to measure the amplitude and phase of the signal beam that travels through the embryo. Four cameras preceded by multiple beamsplitters record the four interferograms that are used within a reconstruction algorithm to produce an image of the complex electric field amplitude. Here we present a model for the electric field through the primary optical components in the imaging configuration and the reconstruction algorithm to calculate the signal to noise ratio when imaging mouse embryos. The model includes magnitude and phase errors in the individual reference and sample paths, fixed pattern noise, and noise within the laser and detectors. This analysis provides the foundation for determining the imaging limitations of OQM and the basis to optimize the cell counting method in order to introduce additional quantitative viability markers.

  9. Radiation transport modeling using extended quadrature method of moments

    SciTech Connect

    Vikas, V.; Hauck, C.D.; Wang, Z.J.; Fox, R.O.

    2013-08-01

    The radiative transfer equation describes the propagation of radiation through a material medium. While it provides a highly accurate description of the radiation field, the large phase space on which the equation is defined makes it numerically challenging. As a consequence, significant effort has gone into the development of accurate approximation methods. Recently, an extended quadrature method of moments (EQMOM) has been developed to solve univariate population balance equations, which also have a large phase space and thus face similar computational challenges. The distinct advantage of the EQMOM approach over other moment methods is that it generates moment equations that are consistent with a positive phase space density and has a moment inversion algorithm that is fast and efficient. The goal of the current paper is to present the EQMOM method in the context of radiation transport, to discuss advantages and disadvantages, and to demonstrate its performance on a set of standard one-dimensional benchmark problems that encompass optically thin, thick, and transition regimes. Special attention is given in the implementation to the issue of realizability—that is, consistency with a positive phase space density. Numerical results in one dimension are promising and lay the foundation for extending the same framework to multiple dimensions.

  10. Quantitative phase imaging using grating-based quadrature phase interferometer

    NASA Astrophysics Data System (ADS)

    Wu, Jigang; Yaqoob, Zahid; Heng, Xin; Cui, Xiquan; Yang, Changhuei

    2007-02-01

    In this paper, we report the use of holographic gratings, which act as the free-space equivalent of the 3x3 fiber-optic coupler, to perform full field phase imaging. By recording two harmonically-related gratings in the same holographic plate, we are able to obtain nontrivial phase shift between different output ports of the gratings-based Mach-Zehnder interferometer. The phase difference can be adjusted by changing the relative phase of the recording beams when recording the hologram. We have built a Mach-Zehnder interferometer using harmonically-related holographic gratings with 600 and 1200 lines/mm spacing. Two CCD cameras at the output ports of the gratings-based Mach-Zehnder interferometer are used to record the full-field quadrature interferograms, which are subsequently processed to reconstruct the phase image. The imaging system has ~12X magnification with ~420μmx315μm field-of-view. To demonstrate the capability of our system, we have successfully performed phase imaging of a pure phase object and a paramecium caudatum.

  11. Electronically Tunable Differential Integrator: Linear Voltage Controlled Quadrature Oscillator.

    PubMed

    Nandi, Rabindranath; Pattanayak, Sandhya; Venkateswaran, Palaniandavar; Das, Sagarika

    2015-01-01

    A new electronically tunable differential integrator (ETDI) and its extension to voltage controlled quadrature oscillator (VCQO) design with linear tuning law are proposed; the active building block is a composite current feedback amplifier with recent multiplication mode current conveyor (MMCC) element. Recently utilization of two different kinds of active devices to form a composite building block is being considered since it yields a superior functional element suitable for improved quality circuit design. The integrator time constant (τ) and the oscillation frequency (ω o ) are tunable by the control voltage (V) of the MMCC block. Analysis indicates negligible phase error (θ e ) for the integrator and low active ω o -sensitivity relative to the device parasitic capacitances. Satisfactory experimental verifications on electronic tunability of some wave shaping applications by the integrator and a double-integrator feedback loop (DIFL) based sinusoid oscillator with linear f o variation range of 60 KHz~1.8 MHz at low THD of 2.1% are verified by both simulation and hardware tests. PMID:27347537

  12. Modulator-free quadrature amplitude modulation signal synthesis

    NASA Astrophysics Data System (ADS)

    Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O'Carroll, John; Phelan, Richard; Richardson, David J.; Slavík, Radan

    2014-12-01

    The ability to generate high-speed on-off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5 Gbit s-1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on-off-keyed 10 Gbit s-1 systems and is absolutely prohibitive for today’s (>)100 Gbit s-1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions.

  13. Homodyne laser interferometer involving minimal quadrature phase error to obtain subnanometer nonlinearity.

    PubMed

    Cui, Junning; He, Zhangqiang; Jiu, Yuanwei; Tan, Jiubin; Sun, Tao

    2016-09-01

    The demand for minimal cyclic nonlinearity error in laser interferometry is increasing as a result of advanced scientific research projects. Research shows that the quadrature phase error is the main effect that introduces cyclic nonlinearity error, and polarization-mixing cross talk during beam splitting is the main error source that causes the quadrature phase error. In this paper, a new homodyne quadrature laser interferometer configuration based on nonpolarization beam splitting and balanced interference between two circularly polarized laser beams is proposed. Theoretical modeling indicates that the polarization-mixing cross talk is elaborately avoided through nonpolarizing and Wollaston beam splitting, with a minimum number of quadrature phase error sources involved. Experimental results show that the cyclic nonlinearity error of the interferometer is up to 0.6 nm (peak-to-valley value) without any correction and can be further suppressed to 0.2 nm with a simple gain and offset correction method. PMID:27607285

  14. Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods.

    PubMed

    Cao, Huiliang; Li, Hongsheng; Kou, Zhiwei; Shi, Yunbo; Tang, Jun; Ma, Zongmin; Shen, Chong; Liu, Jun

    2016-01-01

    This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses' quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups' output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability. PMID:26751455

  15. A fast method of numerical quadrature for p-version finite element matrices

    NASA Technical Reports Server (NTRS)

    Hinnant, Howard E.

    1993-01-01

    A new technique of numerical quadrature especially suited for p-version finite element matrices is presented. This new technique separates the integrand into two parts, and numerically operates on each part separately. The objective of this scheme is to minimize the computational cost of integrating the entire element matrix as opposed to minimizing the cost of integrating a single function. The efficiency of the new technique is compared with Gaussian quadrature and found to take a small fraction of the computational effort.

  16. Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods.

    PubMed

    Cao, Huiliang; Li, Hongsheng; Kou, Zhiwei; Shi, Yunbo; Tang, Jun; Ma, Zongmin; Shen, Chong; Liu, Jun

    2016-01-07

    This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses' quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups' output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability.

  17. Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods

    PubMed Central

    Cao, Huiliang; Li, Hongsheng; Kou, Zhiwei; Shi, Yunbo; Tang, Jun; Ma, Zongmin; Shen, Chong; Liu, Jun

    2016-01-01

    This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses’ quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups’ output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability. PMID:26751455

  18. Directional dual-tree complex wavelet packet transforms for processing quadrature signals.

    PubMed

    Serbes, Gorkem; Gulcur, Halil Ozcan; Aydin, Nizamettin

    2016-03-01

    Quadrature signals containing in-phase and quadrature-phase components are used in many signal processing applications in every field of science and engineering. Specifically, Doppler ultrasound systems used to evaluate cardiovascular disorders noninvasively also result in quadrature format signals. In order to obtain directional blood flow information, the quadrature outputs have to be preprocessed using methods such as asymmetrical and symmetrical phasing filter techniques. These resultant directional signals can be employed in order to detect asymptomatic embolic signals caused by small emboli, which are indicators of a possible future stroke, in the cerebral circulation. Various transform-based methods such as Fourier and wavelet were frequently used in processing embolic signals. However, most of the times, the Fourier and discrete wavelet transforms are not appropriate for the analysis of embolic signals due to their non-stationary time-frequency behavior. Alternatively, discrete wavelet packet transform can perform an adaptive decomposition of the time-frequency axis. In this study, directional discrete wavelet packet transforms, which have the ability to map directional information while processing quadrature signals and have less computational complexity than the existing wavelet packet-based methods, are introduced. The performances of proposed methods are examined in detail by using single-frequency, synthetic narrow-band, and embolic quadrature signals.

  19. Extended Gaussian quadratures for functions with an end-point singularity of logarithmic type

    NASA Astrophysics Data System (ADS)

    Pachucki, K.; Puchalski, M.; Yerokhin, V. A.

    2014-11-01

    The extended Gaussian quadrature rules are shown to be an efficient tool for numerical integration of wide class of functions with singularities of logarithmic type. The quadratures are exact for the functions pol1n-1(x)+lnx pol2n-1(x), where pol1n-1(x) and pol2n-1(x) are two arbitrary polynomials of degree n-1 and n is the order of the quadrature formula. We present an implementation of numerical algorithm that calculates the nodes and the weights of the quadrature formulas, provide a Fortran code for numerical integration, and test the performance of different kinds of Gaussian quadratures for functions with logarithmic singularities. Catalogue identifier: AETP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AETP_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2535 No. of bytes in distributed program, including test data, etc.: 39 963 Distribution format: tar.gz Programming language: Mathematica, Fortran. Computer: PCs or higher performance computers. Operating system: Linux, Windows, MacOS. RAM: Kilobytes. Classification: 4.11. Nature of problem: Quadrature formulas for numerical integration, effective for a wide class of functions with end-point singularities of logarithmic type. Solution method: The method of solution is based on the algorithm developed in Ref. [1] with some modifications. Running time: Milliseconds to minutes. J. Ma, V. Rokhlin, S. Wandzura, Generalized Gaussian quadrature rules for systems of arbitrary functions, Soc. Indust. Appl. Math. J. Numer. Anal. 33 (3) (1996) 971-996.

  20. The generation of arbitrary order, non-classical, Gauss-type quadrature for transport applications

    SciTech Connect

    Spence, Peter J.

    2015-09-01

    A method is presented, based upon the Stieltjes method (1884), for the determination of non-classical Gauss-type quadrature rules, and the associated sets of abscissae and weights. The method is then used to generate a number of quadrature sets, to arbitrary order, which are primarily aimed at deterministic transport calculations. The quadrature rules and sets detailed include arbitrary order reproductions of those presented by Abu-Shumays in [4,8] (known as the QR sets, but labelled QRA here), in addition to a number of new rules and associated sets; these are generated in a similar way, and we label them the QRS quadrature sets. The method presented here shifts the inherent difficulty (encountered by Abu-Shumays) associated with solving the non-linear moment equations, particular to the required quadrature rule, to one of the determination of non-classical weight functions and the subsequent calculation of various associated inner products. Once a quadrature rule has been written in a standard form, with an associated weight function having been identified, the calculation of the required inner products is achieved using specific variable transformations, in addition to the use of rapid, highly accurate quadrature suited to this purpose. The associated non-classical Gauss quadrature sets can then be determined, and this can be done to any order very rapidly. In this paper, instead of listing weights and abscissae for the different quadrature sets detailed (of which there are a number), the MATLAB code written to generate them is included as Appendix D. The accuracy and efficacy (in a transport setting) of the quadrature sets presented is not tested in this paper (although the accuracy of the QRA quadrature sets has been studied in [12,13]), but comparisons to tabulated results listed in [8] are made. When comparisons are made with one of the azimuthal QRA sets detailed in [8], the inherent difficulty in the method of generation, used there, becomes apparent

  1. Design and application of quadrature compensation patterns in bulk silicon micro-gyroscopes.

    PubMed

    Ni, Yunfang; Li, Hongsheng; Huang, Libin

    2014-01-01

    This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. The compensation principle was described first. In the mechanical design, four types of basic structure units were presented to obtain the basic compensation function. A novel layout design was proposed to eliminate the additional disturbing static forces and torques. Parameter optimization was carried out to maximize the available compensation capability in a limited layout area. Two types of voltage loading methods were presented. Their influences on the sense mode dynamics were analyzed. The proposed design was applied on a dual-mass silicon micro-gyroscope developed in our laboratory. The theoretical compensation capability of a quadrature equivalent angular rate no more than 412 °/s was designed. In experiments, an actual quadrature equivalent angular rate of 357 °/s was compensated successfully. The actual compensation voltages were a little larger than the theoretical ones. The correctness of the design and the theoretical analyses was verified. They can be commonly used in planar linear vibratory silicon micro-gyroscopes for quadrature compensation purpose. PMID:25356646

  2. Design and Application of Quadrature Compensation Patterns in Bulk Silicon Micro-Gyroscopes

    PubMed Central

    Ni, Yunfang; Li, Hongsheng; Huang, Libin

    2014-01-01

    This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. The compensation principle was described first. In the mechanical design, four types of basic structure units were presented to obtain the basic compensation function. A novel layout design was proposed to eliminate the additional disturbing static forces and torques. Parameter optimization was carried out to maximize the available compensation capability in a limited layout area. Two types of voltage loading methods were presented. Their influences on the sense mode dynamics were analyzed. The proposed design was applied on a dual-mass silicon micro-gyroscope developed in our laboratory. The theoretical compensation capability of a quadrature equivalent angular rate no more than 412 °/s was designed. In experiments, an actual quadrature equivalent angular rate of 357 °/s was compensated successfully. The actual compensation voltages were a little larger than the theoretical ones. The correctness of the design and the theoretical analyses was verified. They can be commonly used in planar linear vibratory silicon micro-gyroscopes for quadrature compensation purpose. PMID:25356646

  3. Surmounting intrinsic quantum-measurement uncertainties in Gaussian-state tomography with quadrature squeezing

    PubMed Central

    Řeháček, Jaroslav; Teo, Yong Siah; Hradil, Zdeněk; Wallentowitz, Sascha

    2015-01-01

    We reveal that quadrature squeezing can result in significantly better quantum-estimation performance with quantum heterodyne detection (of H. P. Yuen and J. H. Shapiro) as compared to quantum homodyne detection for Gaussian states, which touches an important aspect in the foundational understanding of these two schemes. Taking single-mode Gaussian states as examples, we show analytically that the competition between the errors incurred during tomogram processing in homodyne detection and the Arthurs-Kelly uncertainties arising from simultaneous incompatible quadrature measurements in heterodyne detection can often lead to the latter giving more accurate estimates. This observation is also partly a manifestation of a fundamental relationship between the respective data uncertainties for the two schemes. In this sense, quadrature squeezing can be used to overcome intrinsic quantum-measurement uncertainties in heterodyne detection. PMID:26195198

  4. Low-Latitude Solar Wind During the Fall 1998 SOHO-Ulysses Quadrature

    NASA Technical Reports Server (NTRS)

    Poletto, G.; Suess, S. T.; Biesecker, D. A.; Esser, R.; Gloeckler, G.; Ko, Y.-K.; Zurbuchen, T. H.

    2002-01-01

    Solar and Heliospheric Observatory (SOH0)-Ulysses quadratures occur when the SOHO-Sun-Ulysses-included angle is 90 deg. These offer the opportunity to directly compare properties of plasma parcels, observed by SOHO [Dorningo et al.] in the low corona, with properties of the same parcels measured, in due time, in situ, by Ulysses [ Wenzel et al]. We refer the reader to Suess et al. for an extended discussion of SOHO-Ulysses quadrature geometry. Here it suffices to recall that there are two quadratures per year, as SOHO makes its one-year revolution around the Sun. This, because SOHO is at the L1 Lagrangian point, in essentially the same place as the Earth, while Ulysses is in a near-polar -5-year solar orbit with a perihelion of 1.34 AU and aphelion of 5.4 AU.

  5. Generation of pure electrical quadrature amplitude modulation with photonic vector modulator.

    PubMed

    Corral, Juan L; Sambaraju, Rakesh; Piqueras, Miguel A; Polo, Valentín

    2008-06-15

    A photonic vector modulator architecture for generating pure quadrature amplitude modulation (QAM) signals is presented. An electrical quadrature-modulated signal at microwave-millimeter-wave frequencies is generated from its corresponding baseband in-phase (I) and quadrature (Q) components. In the proposed scheme, no electrical devices apart from the electrical tone oscillator are needed in the generation process. In addition, the purity of the generated signal is increased, and the hardware requirements are reduced when compared with previously proposed architectures so a highly compact low-cost architecture can be implemented. A pure 1.25 Gbit/s 4-QAM signal has been experimentally generated at a 42 GHz carrier frequency.

  6. Quadrature rules for finite element approximations of 1D nonlocal problems

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoping; Gunzburger, Max; Ju, Lili

    2016-04-01

    It is well known that calculations of the entries of the stiffness matrix in the finite element approximations of nonlocal diffusion and mechanics models are often very time-consuming due to the double integration process over the domain and the singularities of the nonlocal kernel functions. In this paper, we propose some effective and accurate quadrature rules for computing these double integrals for one-dimensional nonlocal problems; in particular, for problems with highly singular kernels, the corresponding inner integrals can be first evaluated exactly in our method, and the outer one then will be approximated by some popular quadrature rules. With these quadrature rules, the assembly of the stiffness matrix in the finite element method for the nonlocal problems becomes similar to that for the classical partial differential equations and is thus quite efficient.

  7. Vibration Analysis of Beams Using the Generalized Differential Quadrature Rule and Domain Decomposition

    NASA Astrophysics Data System (ADS)

    LIU, G. R.; WU, T. Y.

    2001-09-01

    This study dealt with domain decomposition in the recently proposed generalized differential quadrature rule. In detail, the authors concentrated on the free vibration of multispan and stepped Euler beams, and beams carrying an intermediate or end concentrated mass. Since compatibility conditions should be implemented in a strong form at the junction of the subdomains concerned, the FEM techniques used for internal moments and shear forces must not be used. Compatibility conditions and their differential quadrature expressions were explicitly formulated. A peculiar phenomenon was found in differential quadrature applications that equal-length subdomains gave more accurate results than unequal-length ones using the same number of subdomain grids. Various examples were presented and very accurate results have been obtained.

  8. Discrete variable representation in electronic structure theory: quadrature grids for least-squares tensor hypercontraction.

    PubMed

    Parrish, Robert M; Hohenstein, Edward G; Martínez, Todd J; Sherrill, C David

    2013-05-21

    We investigate the application of molecular quadratures obtained from either standard Becke-type grids or discrete variable representation (DVR) techniques to the recently developed least-squares tensor hypercontraction (LS-THC) representation of the electron repulsion integral (ERI) tensor. LS-THC uses least-squares fitting to renormalize a two-sided pseudospectral decomposition of the ERI, over a physical-space quadrature grid. While this procedure is technically applicable with any choice of grid, the best efficiency is obtained when the quadrature is tuned to accurately reproduce the overlap metric for quadratic products of the primary orbital basis. Properly selected Becke DFT grids can roughly attain this property. Additionally, we provide algorithms for adopting the DVR techniques of the dynamics community to produce two different classes of grids which approximately attain this property. The simplest algorithm is radial discrete variable representation (R-DVR), which diagonalizes the finite auxiliary-basis representation of the radial coordinate for each atom, and then combines Lebedev-Laikov spherical quadratures and Becke atomic partitioning to produce the full molecular quadrature grid. The other algorithm is full discrete variable representation (F-DVR), which uses approximate simultaneous diagonalization of the finite auxiliary-basis representation of the full position operator to produce non-direct-product quadrature grids. The qualitative features of all three grid classes are discussed, and then the relative efficiencies of these grids are compared in the context of LS-THC-DF-MP2. Coarse Becke grids are found to give essentially the same accuracy and efficiency as R-DVR grids; however, the latter are built from explicit knowledge of the basis set and may guide future development of atom-centered grids. F-DVR is found to provide reasonable accuracy with markedly fewer points than either Becke or R-DVR schemes.

  9. Discrete variable representation in electronic structure theory: quadrature grids for least-squares tensor hypercontraction.

    PubMed

    Parrish, Robert M; Hohenstein, Edward G; Martínez, Todd J; Sherrill, C David

    2013-05-21

    We investigate the application of molecular quadratures obtained from either standard Becke-type grids or discrete variable representation (DVR) techniques to the recently developed least-squares tensor hypercontraction (LS-THC) representation of the electron repulsion integral (ERI) tensor. LS-THC uses least-squares fitting to renormalize a two-sided pseudospectral decomposition of the ERI, over a physical-space quadrature grid. While this procedure is technically applicable with any choice of grid, the best efficiency is obtained when the quadrature is tuned to accurately reproduce the overlap metric for quadratic products of the primary orbital basis. Properly selected Becke DFT grids can roughly attain this property. Additionally, we provide algorithms for adopting the DVR techniques of the dynamics community to produce two different classes of grids which approximately attain this property. The simplest algorithm is radial discrete variable representation (R-DVR), which diagonalizes the finite auxiliary-basis representation of the radial coordinate for each atom, and then combines Lebedev-Laikov spherical quadratures and Becke atomic partitioning to produce the full molecular quadrature grid. The other algorithm is full discrete variable representation (F-DVR), which uses approximate simultaneous diagonalization of the finite auxiliary-basis representation of the full position operator to produce non-direct-product quadrature grids. The qualitative features of all three grid classes are discussed, and then the relative efficiencies of these grids are compared in the context of LS-THC-DF-MP2. Coarse Becke grids are found to give essentially the same accuracy and efficiency as R-DVR grids; however, the latter are built from explicit knowledge of the basis set and may guide future development of atom-centered grids. F-DVR is found to provide reasonable accuracy with markedly fewer points than either Becke or R-DVR schemes. PMID:23697409

  10. Discrete variable representation in electronic structure theory: Quadrature grids for least-squares tensor hypercontraction

    NASA Astrophysics Data System (ADS)

    Parrish, Robert M.; Hohenstein, Edward G.; Martínez, Todd J.; Sherrill, C. David

    2013-05-01

    We investigate the application of molecular quadratures obtained from either standard Becke-type grids or discrete variable representation (DVR) techniques to the recently developed least-squares tensor hypercontraction (LS-THC) representation of the electron repulsion integral (ERI) tensor. LS-THC uses least-squares fitting to renormalize a two-sided pseudospectral decomposition of the ERI, over a physical-space quadrature grid. While this procedure is technically applicable with any choice of grid, the best efficiency is obtained when the quadrature is tuned to accurately reproduce the overlap metric for quadratic products of the primary orbital basis. Properly selected Becke DFT grids can roughly attain this property. Additionally, we provide algorithms for adopting the DVR techniques of the dynamics community to produce two different classes of grids which approximately attain this property. The simplest algorithm is radial discrete variable representation (R-DVR), which diagonalizes the finite auxiliary-basis representation of the radial coordinate for each atom, and then combines Lebedev-Laikov spherical quadratures and Becke atomic partitioning to produce the full molecular quadrature grid. The other algorithm is full discrete variable representation (F-DVR), which uses approximate simultaneous diagonalization of the finite auxiliary-basis representation of the full position operator to produce non-direct-product quadrature grids. The qualitative features of all three grid classes are discussed, and then the relative efficiencies of these grids are compared in the context of LS-THC-DF-MP2. Coarse Becke grids are found to give essentially the same accuracy and efficiency as R-DVR grids; however, the latter are built from explicit knowledge of the basis set and may guide future development of atom-centered grids. F-DVR is found to provide reasonable accuracy with markedly fewer points than either Becke or R-DVR schemes.

  11. Evaluation of quadrature-phase-shift-keying signal characteristics in W-band radio-over-fiber transmission using direct in-phase/quadrature-phase conversion technique

    NASA Astrophysics Data System (ADS)

    Suzuki, Meisaku; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki

    2016-02-01

    The effects of in-phase/quadrature-phase (IQ) imbalances are evaluated with a direct IQ down-converter in the W-band (75-110 GHz). The IQ imbalance of the converter is measured within a range of +/-10 degrees in an intermediate frequency of DC-26.5 GHz. 1-8-G-baud quadrature phase-shift keying (QPSK) signals are transmitted successfully with observed bit error rates within a forward error correction limit of 2×10-3 using radio over fiber (RoF) techniques. The direct down-conversion technique is applicable to next-generation high-speed wireless access communication systems in the millimeter-wave band.

  12. Performance of staggered quadrature modulations over nonlinear satellite channels with uplink noise and intersymbol interference

    NASA Technical Reports Server (NTRS)

    Simon, M. K.; Divsalar, D.; Omura, J. K.

    1982-01-01

    In this paper, the performance of staggered quadrature modulations over nonlinear satellite channels is analyzed. The effects of uplink noise and intersymbol interference caused by transmitter filtering are included. The approach taken employs computational techniques based on moments of the interference. The expressions for the system bit error rate are derived for a general transponder model characterized by AM-AM and AM-PM conversion characteristics. Specific numerical results are presented for a hard-limited satellite repeater using staggered quadrature overlapped raised cosine (SQORC) and minimum-shift-keying (MSK) modulations.

  13. Reduced computational cost, totally symmetric angular quadrature sets for discrete ordinates radiation transport. Master`s thesis

    SciTech Connect

    Oder, J.M.

    1997-12-01

    Several new quadrature sets for use in the discrete ordinates method of solving the Boltzmann neutral particle transport equation are derived. These symmetric quadratures extend the traditional symmetric quadratures by allowing ordinates perpendicular to one or two of the coordinate axes. Comparable accuracy with fewer required ordinates is obtained. Quadratures up to seventh order are presented. The validity and efficiency of the quadratures is then tested and compared with the Sn level symmetric quadratures relative to a Monte Carlo benchmark solution. The criteria for comparison include current through the surface, scalar flux at the surface, volume average scalar flux, and time required for convergence. Appreciable computational cost was saved when used in an unstructured tetrahedral cell code using highly accurate characteristic methods. However, no appreciable savings in computation time was found using the new quadratures compared with traditional Sn methods on a regular Cartesian mesh using the standard diamond difference method. These quadratures are recommended for use in three-dimensional calculations on an unstructured mesh.

  14. Feasibility of heart rate variability measurement from quadrature Doppler radar using arctangent demodulation with DC offset compensation.

    PubMed

    Massagram, Wansuree; Hafner, Noah M; Park, Byung-Kwan; Lubecke, Victor M; Host-Madsen, Anders; Boric-Lubecke, Olga

    2007-01-01

    This paper describes the experimental results of the beat-to-beat interval measurement from a quadrature Doppler radar system utilizing arctangent demodulation with DC offset compensation techniques. The comparison in SDNN and in RMSDD of both signals demonstrates the potential of using quadrature Doppler radar for HRV analysis.

  15. Saturation dependence of the quadrature conductivity of oil-bearing sands

    NASA Astrophysics Data System (ADS)

    Schmutz, M.; Blondel, A.; Revil, A.

    2012-02-01

    We have investigated the complex conductivity of oil-bearing sands with six distinct oil types including sunflower oil, silicone oil, gum rosin, paraffin, engine oil, and an industrial oil of complex composition. In all these experiments, the oil was the non-wetting phase. The in-phase (real) conductivity follows a power law relationship with the saturation (also known as the second Archie's law) but with a saturation exponent n raging from 1.1 to 3.1. In most experiments, the quadrature conductivity follows also a power law relationship with the water saturation but with a power law exponent p can be either positive or negative. For some samples, the quadrature conductivity first increases with saturation and then decreases indicating that two processes compete in controlling the quadrature conductivity. One is related to the insulating nature of the oil phase and a second could be associated with the surface area of the oil / water interface. The quadrature conductivity seems to be influenced not only by the value of the saturation exponent n (according to the Vinegar and Waxman model, p = n - 1), but also by the surface area between the oil phase and the water phase especially for very water-repellent oil having a fractal oil-water interface.

  16. Accurate cell counts in live mouse embryos using optical quadrature and differential interference contrast microscopy

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; Newmark, Judith A.; Zhao, Bing; Warner, Carol M.; DiMarzio, Charles A.

    2006-02-01

    Present imaging techniques used in in vitro fertilization (IVF) clinics are unable to produce accurate cell counts in developing embryos past the eight-cell stage. We have developed a method that has produced accurate cell counts in live mouse embryos ranging from 13-25 cells by combining Differential Interference Contrast (DIC) and Optical Quadrature Microscopy. Optical Quadrature Microscopy is an interferometric imaging modality that measures the amplitude and phase of the signal beam that travels through the embryo. The phase is transformed into an image of optical path length difference, which is used to determine the maximum optical path length deviation of a single cell. DIC microscopy gives distinct cell boundaries for cells within the focal plane when other cells do not lie in the path to the objective. Fitting an ellipse to the boundary of a single cell in the DIC image and combining it with the maximum optical path length deviation of a single cell creates an ellipsoidal model cell of optical path length deviation. Subtracting the model cell from the Optical Quadrature image will either show the optical path length deviation of the culture medium or reveal another cell underneath. Once all the boundaries are used in the DIC image, the subtracted Optical Quadrature image is analyzed to determine the cell boundaries of the remaining cells. The final cell count is produced when no more cells can be subtracted. We have produced exact cell counts on 5 samples, which have been validated by Epi-Fluorescence images of Hoechst stained nuclei.

  17. Numerical Quadrature and Operator Splitting in Finite Element Methods for Cardiac Electrophysiology

    PubMed Central

    Krishnamoorthi, Shankarjee; Sarkar, Mainak; Klug, William S.

    2015-01-01

    SUMMARY We examine carefully the numerical accuracy and computational efficiency of alternative formulations of the finite-element solution procedure for the mono-domain equations of cardiac electrophysiology (EP), focusing on the interaction of spatial quadrature implementations with operator splitting, examining both nodal and Gauss quadrature methods, and implementations that mix nodal storage of state variables with Gauss quadrature. We evaluate the performance of all possible combinations of “lumped” approximations of consistent capacitance and mass matrices. Most generally we find that quadrature schemes and lumped approximations that produce decoupled nodal ionic equations allow for the greatest computational efficiency, this being afforded through the use of asynchronous adaptive time-stepping of the ionic state-variable ODEs. We identify two lumped approximation schemes that exhibit superior accuracy, rivaling that of the most expensive variationally consistent implementations. Finally we illustrate some of the physiological consequences of discretization error in EP simulation relevant to cardiac arrhythmia and fibrillation. These results suggest caution with the use of semi-automated free-form tetrahedral and hexahedral meshing algorithms available in most commercially available meshing software, which produce non-uniform meshes having a large distribution of element sizes. PMID:23873868

  18. Light-controlled resistors provide quadrature signal rejection for high-gain servo systems

    NASA Technical Reports Server (NTRS)

    Mc Cauley, D. D.

    1967-01-01

    Servo amplifier feedback system, in which the phase sensitive detection, low pass filtering, and multiplication functions required for quadrature rejection, are preformed by light-controlled photoresistors, eliminates complex circuitry. System increases gain, improves signal-to-noise ratio, and eliminates the necessity for compensation.

  19. Exact Integrations of Polynomials and Symmetric Quadrature Formulas over Arbitrary Polyhedral Grids

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1997-01-01

    This paper is concerned with two important elements in the high-order accurate spatial discretization of finite volume equations over arbitrary grids. One element is the integration of basis functions over arbitrary domains, which is used in expressing various spatial integrals in terms of discrete unknowns. The other consists of quadrature approximations to those integrals. Only polynomial basis functions applied to polyhedral and polygonal grids are treated here. Non-triangular polygonal faces are subdivided into a union of planar triangular facets, and the resulting triangulated polyhedron is subdivided into a union of tetrahedra. The straight line segment, triangle, and tetrahedron are thus the fundamental shapes that are the building blocks for all integrations and quadrature approximations. Integrals of products up to the fifth order are derived in a unified manner for the three fundamental shapes in terms of the position vectors of vertices. Results are given both in terms of tensor products and products of Cartesian coordinates. The exact polynomial integrals are used to obtain symmetric quadrature approximations of any degree of precision up to five for arbitrary integrals over the three fundamental domains. Using a coordinate-free formulation, simple and rational procedures are developed to derive virtually all quadrature formulas, including some previously unpublished. Four symmetry groups of quadrature points are introduced to derive Gauss formulas, while their limiting forms are used to derive Lobatto formulas. Representative Gauss and Lobatto formulas are tabulated. The relative efficiency of their application to polyhedral and polygonal grids is detailed. The extension to higher degrees of precision is discussed.

  20. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging.

    PubMed

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-02-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than -35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla. PMID:24649430

  1. Numerical quadrature methods for integrals of singular periodic functions and their application to singular and weakly singular integral equations

    NASA Technical Reports Server (NTRS)

    Sidi, A.; Israeli, M.

    1986-01-01

    High accuracy numerical quadrature methods for integrals of singular periodic functions are proposed. These methods are based on the appropriate Euler-Maclaurin expansions of trapezoidal rule approximations and their extrapolations. They are used to obtain accurate quadrature methods for the solution of singular and weakly singular Fredholm integral equations. Such periodic equations are used in the solution of planar elliptic boundary value problems, elasticity, potential theory, conformal mapping, boundary element methods, free surface flows, etc. The use of the quadrature methods is demonstrated with numerical examples.

  2. Unstructured finite element-based digital image correlation with enhanced management of quadrature and lens distortions

    NASA Astrophysics Data System (ADS)

    Pierré, J.-E.; Passieux, J.-C.; Périé, J.-N.; Bugarin, F.; Robert, L.

    2016-02-01

    Like subset-based methods, the very first finite element versions of digital image correlation were closely related to the regular structure of images, as they were based on regular quadrilateral elements corresponding to an integer number of pixels. The use of unstructured meshes, to exploit the full potential of FE-DIC in structural mechanics, is now widespread. Most of the time, the formulation, the quadrature and the definition of the region of interest still rely on the pixels grid. In this paper, a formulation in the physical coordinate system and not in the image frame is proposed for 2D digital image correlation. In addition to a more precise definition of the region of interest, it allows the use of a more accurate quadrature rule. It is also shown that lens distortions can be successfully taken into account directly with such a formalism.

  3. Diffusion-synthetic acceleration given anisotropic scattering, general quadratures, and multidimensions

    SciTech Connect

    Adams, M.L. ); Wareing, T.A. )

    1993-01-01

    We study diffusion-synthetic acceleration (DSA) for within-group scattering iterations in discrete ordinates calculations. We consider analytic (not spatially discretized) equations in Cartesian coordinates with linearly anisotropic scattering. We place no restrictions on the discrete ordinates quadrature set. We assume an infinite homogeneous medium. Our main results are as follows: 1. DSA is unstable in two dimensions (2D) and three dimensions (3D), given forward-peaked scattering. It can be stabilized by taking extra transport sweeps each iteration. 2. Standard DSA is unstable, given any quadrature set that does not correctly integrate linear functions of angle. 3. Relative to one dimension (ID), DSA's performance is degraded in 2D and 3D.

  4. Solution of stochastic media transport problems using a numerical quadrature-based method

    SciTech Connect

    Pautz, S. D.; Franke, B. C.; Prinja, A. K.; Olson, A. J.

    2013-07-01

    We present a new conceptual framework for analyzing transport problems in random media. We decompose such problems into stratified subproblems according to the number of material pseudo-interfaces within realizations. For a given subproblem we assign pseudo-interface locations in each realization according to product quadrature rules, which allows us to deterministically generate a fixed number of realizations. Quadrature integration of the solutions of these realizations thus approximately solves each subproblem; the weighted superposition of solutions of the subproblems approximately solves the general stochastic media transport problem. We revisit some benchmark problems to determine the accuracy and efficiency of this approach in comparison to randomly generated realizations. We find that this method is very accurate and fast when the number of pseudo-interfaces in a problem is generally low, but that these advantages quickly degrade as the number of pseudo-interfaces increases. (authors)

  5. On the implementation of a modified Sag-Szekeres quadrature method

    SciTech Connect

    Lyness, J.N.; Delves, L.M.

    1997-07-01

    The authors describe a modified Sag-Szekeres multidimensional quadrature algorithm and discuss its implementation as a general-purpose library procedure on serial and parallel architectures. Examples illustrate its effectiveness for both smooth and singular integrands. The procedure has been implemented as a parallel library routine, running on transputer-based systems, as part of Esprit project P2528: Supernode II; (see Plowman (1992)). This routine is scheduled to appear in the quadrature section of the Liverpool-NAG Transputer Software Library. The authors give here some results obtained using this routine, to demonstrate the rapid convergence obtained with both smooth and singular integrands, and to demonstrate the routine`s effectiveness on a parallel NIMD architecture.

  6. Analysis of V-cycle multigrid algorithms for forms defined by numerical quadrature

    SciTech Connect

    Bramble, J.H. . Dept. of Mathematics); Goldstein, C.I.; Pasciak, J.E. . Applied Mathematics Dept.)

    1994-05-01

    The authors describe and analyze certain V-cycle multigrid algorithms with forms defined by numerical quadrature applied to the approximation of symmetric second-order elliptic boundary value problems. This approach can be used for the efficient solution of finite element systems resulting from numerical quadrature as well as systems arising from finite difference discretizations. The results are based on a regularity free theory and hence apply to meshes with local grid refinement as well as the quasi-uniform case. It is shown that uniform (independent of the number of levels) convergence rates often hold for appropriately defined V-cycle algorithms with as few as one smoothing per grid. These results hold even on applications without full elliptic regularity, e.g., a domain in R[sup 2] with a crack.

  7. Tools for detecting entanglement between different degrees of freedom in quadrature squeezed cylindrically polarized modes

    NASA Astrophysics Data System (ADS)

    Gabriel, C.; Aiello, A.; Berg-Johansen, S.; Marquardt, Ch.; Leuchs, G.

    2012-07-01

    Quadrature squeezed cylindrically polarized modes contain entanglement not only in the polarization and spatial electric field variables but also between these two degrees of freedom [C. Gabriel et al., Phys. Rev. Lett. 106, 060502 (2011)]. In this paper we present tools to generate and detect this entanglement. Experimentally we demonstrate the generation of quadrature squeezing in cylindrically polarized modes by mode transforming a squeezed Gaussian mode. Specifically, -1.2 dB ± 0.1 dB of amplitude squeezing are achieved in the radially and azimuthally polarized mode. Furthermore, theoretically it is shown how the entanglement contained within these modes can be measured and how strong the quantum correlations are, depending on the measurement scheme.

  8. Noncritical quadrature squeezing in two-transverse-mode optical parametric oscillators

    SciTech Connect

    Navarrete-Benlloch, Carlos; Roldan, Eugenio; Valcarcel, German J. de; Romanelli, Alejandro

    2010-04-15

    In this article we explore the quantum properties of a degenerate optical parametric oscillator when it is tuned to the first family of transverse modes at the down-converted frequency. Recently we found [C. Navarrete-Benlloch et al., Phys. Rev. Lett. 100, 203601 (2008)] that above threshold a TEM{sub 10} mode following a random rotation in the transverse plane emerges in this system (we denote it as the bright mode), breaking thus its rotational invariance. Then, owing to the mode orientation being undetermined, we showed that the phase quadrature of the transverse mode orthogonal to this one (denoted as the dark mode) is perfectly squeezed at any pump level and without an increase in the fluctuations on its amplitude quadrature (which seems to contradict the uncertainty principle). In this article we go further in the study of this system and analyze some important features not considered previously. First we show that the apparent violation of the uncertainty principle is just that -'apparent' - as the conjugate pair of the squeezed quadrature is not another quadrature but the orientation of the bright mode (which is completely undetermined in the long term). We also study a homodyne scheme in which the local oscillator is not perfectly matched to the dark mode, as this could be impossible in real experiments due to the random rotation of the mode, showing that even in this case large levels of noise reduction can be obtained (also including the experimentally unavoidable phase fluctuations). Finally, we show that neither the adiabatic elimination of the pump variables nor the linearization of the quantum equations are responsible for the remarkable properties of the dark mode (which we prove analytically and through numerical simulations, respectively), which were simplifying assumptions used in Navarrete-Benlloch et al. [Phys. Rev. Lett. 100, 203601 (2008)]. These studies show that the production of noncritically squeezed light through spontaneous rotational

  9. Quadrature conductivity: A quantitative indicator of bacterial abundance in porous media

    SciTech Connect

    Chi Zhang; Andre Revil; Yoshiko Fujita; Junko Munakata-Marr; George Redden

    2014-09-01

    ABSTRACT The abundance and growth stages of bacteria in subsurface porous media affect the concentrations and distributions of charged species within the solid-solution interfaces. Therefore, spectral induced polarization (SIP) measurements can be used to monitor changes in bacterial biomass and growth stage. Our goal was to gain a better understanding of the SIP response of bacteria present in a porous material. Bacterial cell surfaces possess an electric double layer and therefore become polarized in an electric field. We performed SIP measurements over the frequency range of 0.1–1 kHz on cell suspensions alone and cell suspensions mixed with sand at four pore water conductivities. We used Zymomonas mobilis at four different cell densities (in- cluding the background). The quadrature conductivity spectra exhibited two peaks, one around 0.05–0.10 Hz and the other around 1–10 Hz. Because SIP measurements on bacterial suspensions are typically made at frequencies greater than 1 Hz, these peaks have not been previously reported. In the bac-terial suspensions in growth medium, the quadrature conduc-tivity at peak I was linearly proportional to the density of the bacteria. For the case of the suspensions mixed with sands, we observed that peak II presented a smaller increase in the quadrature conductivity with the cell density. A comparison of the experiments with and without sand grains illustrated the effect of the porous medium on the overall quadrature con- ductivity response (decrease in the amplitude and shift of the peaks to the lower frequencies). Our results indicate that for a given porous medium, time-lapse SIP has potential for mon- itoring changes in bacterial abundance within porous media.

  10. 2.5-D/3-D resistivity modelling in anisotropic media using Gaussian quadrature grids

    NASA Astrophysics Data System (ADS)

    Zhou, Bing; Greenhalgh, Mark; Greenhalgh, S. A.

    2009-01-01

    We present a new numerical scheme for 2.5-D/3-D direct current resistivity modelling in heterogeneous, anisotropic media. This method, named the `Gaussian quadrature grid' (GQG) method, cooperatively combines the solution of the Variational Principle of the partial differential equation, Gaussian quadrature abscissae and local cardinal functions so that it has the main advantages of the spectral element method. The formulation shows that the GQG method is a modification of the spectral element method but does not employ the constant elements or require the mesh generator to match the Earth's surface. This makes it much easier to deal with geological models having a 2-D/3-D complex topography than using traditional numerical methods. The GQG technique can achieve a similar convergence rate to the spectral element method. We show it transforms the 2.5-D/3-D resistivity modelling problem into a sparse and symmetric linear equation system that can be solved by an iterative or matrix inversion method. Comparison with analytic solutions for homogeneous isotropic and anisotropic models shows that the error depends on the Gaussian quadrature order (abscissa number) and the subdomain size. The higher the order or the smaller the subdomain size that is employed, the more accurate are the results obtained. Several other synthetic examples, both homogeneous and inhomogeneous, incorporating sloping, undulating and severe topography, are presented and found to yield results comparable to finite element solutions involving a dense mesh.

  11. Quadrature rules for weakly singular, strongly singular, and hypersingular integrals in boundary integral equation methods

    NASA Astrophysics Data System (ADS)

    Tsalamengas, John L.

    2015-12-01

    We present n-point Gauss-Gegenbauer quadrature rules for weakly singular, strongly singular, and hypersingular integrals that arise in integral equation formulations of potential problems in domains with edges and corners. The rules are tailored to weight functions with algebraic endpoint singularities related to the geometrical singularities of the domain. Each rule has two different expressions involving Legendre functions and hypergeometric functions, respectively. Numerical examples amply demonstrate the accuracy and stability of the proposed algorithms. Application to the solution of a singular integral equation is exemplified.

  12. Exponential characteristic spatial quadrature for discrete ordinates radiation transport on an unstructured grid of triangular cells

    SciTech Connect

    Mathews, K.A.; Brennan, C.R.

    1995-12-31

    The exponential characteristic method is one of a family of nonlinear spatial quadratures which are positive and at least second order accurate. The authors initially developed the method in slab geometry, where it gave accurate results for deep penetration problems using coarse meshes. Characteristic methods are restricted to Cartesian geometries, so they next tested it with rectangular cells, where it was again a strong performer. Here the authors extend the method to unstructured grids of arbitrarily shaped and oriented triangles and report on its performance.

  13. Computational signal-to-noise ratio analysis for optical quadrature microscopy.

    PubMed

    Warger, William C; DiMarzio, Charles A

    2009-02-16

    Optical quadrature microscopy (OQM) was invented in 1997 to reconstruct a full-field image of quantitative phase, and has been used to count the number of cells in live mouse embryos. Here we present a thorough SNR analysis that incorporates noise terms for fluctuations in the laser, aberrations within the individual paths of the Mach-Zehnder interferometer, and imperfections within the beamsplitters and CCD cameras to create a model for the resultant phase measurements. The current RMS error of the OQM phase images has been calculated to be 0.08 radians from substituting images from the instrumentation into the model.

  14. A Synthetic Quadrature Phase Detector/Demodulator for Fourier Transform Transform Spectrometers

    NASA Technical Reports Server (NTRS)

    Campbell, Joel

    2008-01-01

    A method is developed to demodulate (velocity correct) Fourier transform spectrometer (FTS) data that is taken with an analog to digital converter that digitizes equally spaced in time. This method makes it possible to use simple low cost, high resolution audio digitizers to record high quality data without the need for an event timer or quadrature laser hardware, and makes it possible to use a metrology laser of any wavelength. The reduced parts count and simplicity implementation makes it an attractive alternative in space based applications when compared to previous methods such as the Brault algorithm.

  15. Solitary wave simulations of Complex Modified Korteweg-de Vries Equation using differential quadrature method

    NASA Astrophysics Data System (ADS)

    Korkmaz, Alper; Dağ, İdris

    2009-09-01

    Complex Modified Korteweg-deVries Equation is solved numerically using differential quadrature method based on cosine expansion. Three test problems, motion of single solitary wave, interaction of solitary waves and wave generation, are simulated. The accuracy of the method is measured via the discrete root mean square error norm L, maximum error norm L for the motion of single solitary wave since it has an analytical solution. A rate of convergency analysis for motion of single solitary wave containing both real and imaginary parts is also given. Lowest three conserved quantities are computed for all test problems. A comparison with some earlier works is given.

  16. Optimization of quadrature signal processing for laser interferometers for demanding applications

    NASA Astrophysics Data System (ADS)

    PodŻorny, Tomasz; Budzyń, Grzegorz; Tkaczyk, Jakub

    2016-06-01

    Presented paper performs an analysis of quadrature signal processing algorithms for high demanding laser interferometry applications. Careful signal processing is required to minimize nonlinearities which come from optical path and components' imperfections, and reduce overall instrumental error. Paper focuses on algebraic fits, because implementation for real time systems was a main requirement. The most demanding applications are stationary measurements where the position slightly fluctuates in the range below one fringe period. Therefore, analysis was performed for samples that were spread along a few milliradians of a full circle.

  17. Ixaru's extended frequency dependent quadrature rules for slater integrals: Parallel computation issues

    NASA Astrophysics Data System (ADS)

    Scott, N. S.; Scott, M. P.; Jézéquel, F.

    2012-09-01

    We describe recent progress of an ongoing research programme aimed at producing computational science software that can exploit high performance architectures in the atomic physics application domain. We examine the computational bottleneck of matrix construction in a suite of two-dimensional R-matrix propagation programs, 2DRMP, that are aimed at creating virtual electron collision experiments on HPC architectures. We build on Ixaru's extended frequency dependent quadrature rules (EFDQR) for Slater integrals and examine the challenge of constructing Hamiltonian matrices in parallel across an m-processor compute node in a block cyclic distribution for subsequent diagonalization by ScaLAPACK.

  18. Extremal states for photon number and quadratures as gauges for nonclassicality

    NASA Astrophysics Data System (ADS)

    Hradil, Z.; Řeháček, J.; de la Hoz, P.; Leuchs, G.; Sánchez-Soto, L. L.

    2015-04-01

    Rotated quadratures carry the phase-dependent information of the electromagnetic field, so they are somehow conjugate to the photon number. We analyze this noncanonical pair, finding an exact uncertainty relation, as well as a couple of weaker inequalities obtained by relaxing some restrictions of the problem. We also find the intelligent states saturating that relation and complete their characterization by considering extra constraints on the second-order moments of the variables involved. Using these moments, we construct performance measures tailored to diagnose photon-added and Schrödinger-cat-like states, among others.

  19. Low-Latitude Solar Wind During the Fall 1998 SOHO-Ulysses Quadrature

    NASA Technical Reports Server (NTRS)

    Poletto, G.; Suess, Steven T.; Biesecker, D.; Esser, R.; Gloeckler, G.; Zurbuchen, T.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The Fall 1998 SOlar-Heliospheric Observatory (SOHO) - Ulysses quadrature occurred when Ulysses was at 5.2 AU, 17.4 deg South of the equator, and off the West line of the Sun. SOHO coronal observations, at heliocentric distances of a few solar radii, showed that the line through the solar center and Ulysses crossed, over the first days of observations, a dark, weakly emitting area and through the northern edge of a streamer complex during the second half of the quadrature campaign. Ulysses in situ observations showed this transition to correspond to a decrease from higher speed wind typical of coronal hole flow to low speed wind. Physical parameters (density, temperature, flow speed) of the low latitude coronal plasma sampled over the campaign are determined using constraints from what is the same plasma measured later in situ and simulating the intensities of the Hydrogen Lyman-alpha and OVI 1032 and 1037 Angstrom lines, measured by the Ultra Violet Coronagraph Spectrometer (UVCS) on SOHO. The densities, temperatures and outflow speed are compared with the same characteristic flow parameters for high-latitude fast wind streams and typical slow solar wind.

  20. A quadrature based method of moments for nonlinear Fokker-Planck equations

    NASA Astrophysics Data System (ADS)

    Otten, Dustin L.; Vedula, Prakash

    2011-09-01

    Fokker-Planck equations which are nonlinear with respect to their probability densities and occur in many nonequilibrium systems relevant to mean field interaction models, plasmas, fermions and bosons can be challenging to solve numerically. To address some underlying challenges, we propose the application of the direct quadrature based method of moments (DQMOM) for efficient and accurate determination of transient (and stationary) solutions of nonlinear Fokker-Planck equations (NLFPEs). In DQMOM, probability density (or other distribution) functions are represented using a finite collection of Dirac delta functions, characterized by quadrature weights and locations (or abscissas) that are determined based on constraints due to evolution of generalized moments. Three particular examples of nonlinear Fokker-Planck equations considered in this paper include descriptions of: (i) the Shimizu-Yamada model, (ii) the Desai-Zwanzig model (both of which have been developed as models of muscular contraction) and (iii) fermions and bosons. Results based on DQMOM, for the transient and stationary solutions of the nonlinear Fokker-Planck equations, have been found to be in good agreement with other available analytical and numerical approaches. It is also shown that approximate reconstruction of the underlying probability density function from moments obtained from DQMOM can be satisfactorily achieved using a maximum entropy method.

  1. Evaluation of angular quadrature and spatial differencing schemes for discrete ordinates method in rectangular furnaces

    SciTech Connect

    Selcuk, N.; Kayakol, N.

    1996-11-01

    Effects of order of approximation (S{sub 2} and S{sub 4}), angular quadrature (S{sub n} and S{sub n}{prime}) and spatial differencing (diamond and variable-weight) schemes, on the predictive accuracy of discrete ordinates method were investigated by predicting the distributions of radiative flux density and source term of a rectangular enclosure problem and comparing the results with exact solutions produced previously. The enclosure problem is based on data reported earlier on a large-scale experimental furnace with steep temperature gradients. It is a black-walled enclosure containing an absorbing-emitting medium of constant properties. Comparisons show that better agreement is obtained in radiative energy source terms than in flux densities and that the order of approximation plays a more significant role than angular quadrature and spatial differencing schemes in the accuracy of predicted radiative flux densities and radiative energy source terms. Only slight improvements are obtained when S{sub n} and variable-weight differencing schemes are employed.

  2. Exponential characteristics spatial quadrature for discrete ordinates radiation transport in slab geometry

    SciTech Connect

    Mathews, K.; Sjoden, G.; Minor, B. )

    1994-09-01

    The exponential characteristic spatial quadrature for discrete ordinates neutral particle transport in slab geometry is derived and compared with current methods. It is similar to the linear characteristic (or, in slab geometry, the linear nodal) quadrature but differs by assuming an exponential distribution of the scattering source within each cell, S(x) = a exp(bx), whose parameters are root-solved to match the known (from the previous iteration) average and first moment of the source over the cell. Like the linear adaptive method, the exponential characteristic method is positive and nonlinear but more accurate and more readily extended to other cell shapes. The nonlinearity has not interfered with convergence. The authors introduce the exponential moment functions,'' a generalization of the functions used by Walters in the linear nodal method, and use them to avoid numerical ill-conditioning. The method exhibits O([Delta]x[sup 4]) truncation error on fine enough meshes; the error is insensitive to mesh size for coarse meshes. In a shielding problem, it is accurate to 10% using 16-mfp-thick cells; conventional methods err by 8 to 15 orders of magnitude. The exponential characteristic method is computationally more costly per cell than current methods but can be accurate with very thick cells, leading to increased computational efficiency on appropriate problems.

  3. First CFOA-based explicit-current-output quadrature sinusoidal oscillators using grounded capacitors

    NASA Astrophysics Data System (ADS)

    Lahiri, Abhirup; Jaikla, Winai; Siripruchyanun, Montree

    2013-02-01

    To date, no current-feedback operational amplifier (CFOA)-based sinusoidal oscillator has been reported which provides all the following features simultaneously: (i) current-mode quadrature sinusoidal oscillator providing two explicit-current-outputs (ECOs) from high output impedance terminals, (ii) employing no more than three CFOA ICs and six passive components, which include two grounded capacitors, (iii) offers independent tuning of the condition of oscillation (CO) via a resistor and (iv) provides tunability of the ratio of amplitudes of the generated quadrature ECOs via a separate resistor. To the best of authors' knowledge, this article reports first CFOA-based QOs in current-mode (i.e. providing two ECO signals). Experimental results using AD844 CFOA ICs from Analog Devices have been included to verify the workability of the proposed oscillator circuits. An example automatic gain control (AGC) loop to regulate the oscillation amplitude and control the THD has also been used and verified using SPICE simulations using the AD844 macro-model.

  4. A dual-band quadrature VCO with gain proportional to oscillation frequency

    NASA Astrophysics Data System (ADS)

    Wenrui, Zhu; Haigang, Yang; Tongqiang, Gao; Hui, Zhang

    2013-08-01

    This paper presents a novel dual-band quadrature voltage controlled oscillator (VCO) with the gain proportional to the oscillation frequency. Frequency synthesizers with this VCO can reduce the bandwidth fluctuation over all the frequency ranges without compensation or calibration. Besides the original switched capacitor array, an extra switched varactor array is adopted for the implementation of the proposed VCO. The tuning technique of changing the values of the capacitor and varactor at the same ratio is also derived. For verification purposes, a 2.5 G/3.5 G dual-band quadrature VCO is fabricated in a 0.13 μm CMOS process for WiMAX applications. Measurement results show that the VCO gain is closely proportional to the oscillation frequency with ±16% variation over the entire frequency range. The phase noise is -138.15 dBc/Hz at 10 MHz from the 2.5 GHz carrier and -137.44 dBc/Hz at 10 MHz from the 3.5 GHz carrier.

  5. Achromatic registration of quadrature components of the optical spectrum in spectral domain optical coherence tomography

    SciTech Connect

    Shilyagin, P A; Gelikonov, G V; Gelikonov, V M; Moiseev, A A; Terpelov, D A

    2014-07-31

    We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase shift achromatism over a wide spectral range is achieved by using in the delay lines the individual elements with different dispersion characteristics. The ranges of admissible adjustment parameters of the achromatised delay line are estimated for exact and inexact conformity of the geometric characteristics of its components to those calculated. A possibility of simultaneous recording of the close-to-quadrature spectral components with a single linear photodetector element is experimentally confirmed. The suppression of the artefact mirror peak in the OCT-signal by an additional 9 dB relative to the level of its suppression is experimentally achieved when the air delay line is used. Two-dimensional images of the surface positioned at an angle to the axis of the probe beam are obtained with the correction of the 'mirror' artefact while maintaining the dynamic range of the image. (laser biophotonics)

  6. Methods to Prescribe Particle Motion to Minimize Quadrature Error in Meshfree Methods

    NASA Astrophysics Data System (ADS)

    Templeton, Jeremy; Erickson, Lindsay; Morris, Karla; Poliakoff, David

    2015-11-01

    Meshfree methods are an attractive approach for simulating material systems undergoing large-scale deformation, such as spray break up, free surface flows, and droplets. Particles, which can be easily moved, are used as nodes and/or quadrature points rather than a relying on a fixed mesh. Most methods move particles according to the local fluid velocity that allows for the convection terms in the Navier-Stokes equations to be easily accounted for. However, this is a trade-off against numerical accuracy as the flow can often move particles to configurations with high quadrature error, and artificial compressibility is often required to prevent particles from forming undesirable regions of high and low concentrations. In this work, we consider the other side of the trade-off: moving particles based on reducing numerical error. Methods derived from molecular dynamics show that particles can be moved to minimize a surrogate for the solution error, resulting in substantially more accurate simulations at a fixed cost. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  7. Suppressing the mechanical quadrature error of a quartz double-H gyroscope through laser trimming

    NASA Astrophysics Data System (ADS)

    Zhao, Ke; Feng, Li-Hui; Wang, Qian-Qian; Liu, Ming-Zhi; Wang, Ben-Guo; Cui, Fang; Sun, Yu-Nan

    2013-11-01

    In this paper, we introduce a z-axis quartz gyroscope using a double-H tuning fork, which has a high sensitivity. However, it also causes a large mechanical quadrature error. The laser trimming method is used to suppress this error at quartz level. The trimming law is obtained through the finite element method (FEM). A femtosecond laser processing system is used to trim the gold balancing masses on the beams, and experimental results are basically consistent with the simulated ones. The mechanical quadrature error is suppressed by 96%, from 26.3° s-1 to 1.1° s-1. Nonlinearity changes from 1.48% to 0.30%, angular random walk (ARW) is reduced from 2.19° h-1/2 to 1.42° h-1/2, and bias instability is improved by a factor of 7.7, from 197.6° h-1 to 25.4° h-1.

  8. Application of Quadrature Methods for Re-Weighting in Lattice QCD

    SciTech Connect

    Abdou Abdel-Rehim, William Detmold, Kostas Orginos

    2011-12-01

    Re-weighting is a useful tool that has been employed in Lattice QCD in different contexts including, tuning the strange quark mass, approaching the light quark mass regime, and simulating electromagnetic fields on top of QCD gauge configurations. In case of re-weighting the sea quark mass, the re-weighting factor is given by the ratio of the determinants of two Dirac operators D{sub a} and D{sub b}. A popular approach for computing this ratio is to use a pseudofermion representation of the determinant of the composite operator {Omega} = D{sub a}(D{sub b}{sup {dagger}}D{sub b}){sup -1} D{sub a}{sup {dagger}}. Here, we study using quadrature methods together with noise vectors to compute the ratio of determinants. We show that, with quadrature methods each determinant can be computed separately using the operators {Omega}{sub a} = D{sub a}{sup {dagger}}D{sub a} and {Omega}{sub b} = D{sub b}{sup {dagger}} D{sub b}. We also discuss using bootstrap re-sampling to remove the bias from the determinant estimator.

  9. Using a Non-Product Quadrature Grid to Compute the Vibrational Spectrum of C2H4

    NASA Astrophysics Data System (ADS)

    Avila, Gustavo; Carrington, Tucker Carrington, Jr.

    2011-06-01

    We present an accurate 12-D basis set calculation of the lowest 100 energy levels of the C2H4 molecule. A Smolyak non-product quadrature grid, a pruned product basis set, and the Lanczos algorithm are used. This scheme allows one to reduce the size of the basis set by almost 7 orders of magnitude (from 9× 1012 to 1.3× 106) and the size of the quadrature grid by almost 6 orders of magnitude (from 5.6× 1013 to 1.52 × 108). Basis pruning and the nonproduct quadrature grid therefore enable us to solve a problem, numerically exactly, that would be impossible without these tools.

  10. Real-Time Quadrature Measurement of a Single-Photon Wave Packet with Continuous Temporal-Mode Matching

    NASA Astrophysics Data System (ADS)

    Ogawa, Hisashi; Ohdan, Hideaki; Miyata, Kazunori; Taguchi, Masahiro; Makino, Kenzo; Yonezawa, Hidehiro; Yoshikawa, Jun-ichi; Furusawa, Akira

    2016-06-01

    Real-time controls based on quantum measurements are powerful tools for various quantum protocols. However, their experimental realization has been limited by mode mismatch between the temporal mode of quadrature measurement and that heralded by photon detection. Here, we demonstrate real-time quadrature measurement of a single-photon wave packet induced by photon detection by utilizing continuous temporal-mode matching between homodyne detection and an exponentially rising temporal mode. Single photons in exponentially rising modes are also expected to be useful resources for interactions with other quantum systems.

  11. Real-Time Quadrature Measurement of a Single-Photon Wave Packet with Continuous Temporal-Mode Matching.

    PubMed

    Ogawa, Hisashi; Ohdan, Hideaki; Miyata, Kazunori; Taguchi, Masahiro; Makino, Kenzo; Yonezawa, Hidehiro; Yoshikawa, Jun-Ichi; Furusawa, Akira

    2016-06-10

    Real-time controls based on quantum measurements are powerful tools for various quantum protocols. However, their experimental realization has been limited by mode mismatch between the temporal mode of quadrature measurement and that heralded by photon detection. Here, we demonstrate real-time quadrature measurement of a single-photon wave packet induced by photon detection by utilizing continuous temporal-mode matching between homodyne detection and an exponentially rising temporal mode. Single photons in exponentially rising modes are also expected to be useful resources for interactions with other quantum systems.

  12. Numerical Study of Two-Dimensional Reaction-Diffusion Brusselator System by Differential Quadrature Method

    NASA Astrophysics Data System (ADS)

    Mittal, R. C.; Jiwari, Ram

    2011-01-01

    In this paper, a rapid, convergent and accurate differential quadrature method (DQM) is employed for numerical study of a two-dimensional reaction-diffusion Brusselator system. In the Brusselator system the reaction terms arise from the mathematical modeling of chemical systems such as in enzymatic reactions, and in plasma and laser physics in multiple coupling between modes. By employing DQM, accurate results can be obtained using fewer grid points in spatial domain for a large value of T = 50. We also found that Chebyshev-Gauss-Lobatto grid points give excellent results in comparison to other grid points such as uniform grid points. Three examples are solved to illustrate the accuracy and efficiency of the DQM. Convergence and stability of the method is also examined.

  13. Stress fields around two pores in an elastic body: exact quadrature domain solutions

    PubMed Central

    Crowdy, Darren

    2015-01-01

    Analytical solutions are given for the stress fields, in both compression and far-field shear, in a two-dimensional elastic body containing two interacting non-circular pores. The two complex potentials governing the solutions are found by using a conformal mapping from a pre-image annulus with those potentials expressed in terms of the Schottky–Klein prime function for the annulus. Solutions for a three-parameter family of elastic bodies with two equal symmetric pores are presented and the compressibility of a special family of pore pairs is studied in detail. The methodology extends to two unequal pores. The importance for boundary value problems of plane elasticity of a special class of planar domains known as quadrature domains is also elucidated. This observation provides the route to generalization of the mathematical approach here to finding analytical solutions for the stress fields in bodies containing any finite number of pores. PMID:26339198

  14. Spherical-earth gravity and magnetic anomaly modeling by Gauss-Legendre quadrature integration

    NASA Technical Reports Server (NTRS)

    Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J.

    1981-01-01

    Gauss-Legendre quadrature integration is used to calculate the anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical earth. The procedure involves representation of the anomalous source as a distribution of equivalent point gravity poles or point magnetic dipoles. The distribution of equivalent point sources is determined directly from the volume limits of the anomalous body. The variable limits of integration for an arbitrarily shaped body are obtained from interpolations performed on a set of body points which approximate the body's surface envelope. The versatility of the method is shown by its ability to treat physical property variations within the source volume as well as variable magnetic fields over the source and observation surface. Examples are provided which illustrate the capabilities of the technique, including a preliminary modeling of potential field signatures for the Mississippi embayment crustal structure at 450 km.

  15. Instrument Reflections and Scene Amplitude Modulation in a Polychromatic Microwave Quadrature Interferometer

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Jones, Jonathan E.; Chavers, Greg

    2003-01-01

    A polychromatic microwave quadrature interferometer has been characterized using several laboratory plasmas. Reflections between the transmitter and the receiver have been observed, and the effects of including reflection terms in the data reduction equation have been examined. An error analysis which includes the reflections, modulation of the scene beam amplitude by the plasma, and simultaneous measurements at two frequencies has been applied to the empirical database, and the results are summarized. For reflection amplitudes around 1096, the reflection terms were found to reduce the calculated error bars for electron density measurements by about a factor of 2. The impact of amplitude modulation is also quantified. In the complete analysis, the mean error bar for high- density measurements is 7.596, and the mean phase shift error for low-density measurements is 1.2". .

  16. Atom-assisted quadrature squeezing of a mechanical oscillator inside a dispersive cavity

    NASA Astrophysics Data System (ADS)

    Chauhan, Anil Kumar; Biswas, Asoka

    2016-08-01

    We present a hybrid optomechanical scheme to achieve dynamical squeezing of position quadrature of a mesoscopic mechanical oscillator, that can be externally controlled by classical fields. A membrane-in-the-middle setup is employed, in which an atom in Λ configuration is considered to be trapped on either side of the membrane inside the cavity. We show that a considerable amount of squeezing (beyond the 3-dB limit) can be achieved and maintained at a transient time scale that is not affected by the spontaneous emission of the atom. Squeezing depends upon the initial preparation of atomic states. Further, a strong effective coupling (larger than the relevant decay rates) between the atom and the oscillator can be attained by using large control fields that pump the atom and the cavity. The effects of cavity decay and the phononic bath on squeezing are studied. The results are supported by the detailed analytical calculations.

  17. Reconfigurable microwave photonic in-phase and quadrature detector for frequency agile radar.

    PubMed

    Emami, Hossein; Sarkhosh, Niusha

    2014-06-01

    A microwave photonic in-phase and quadrature detector is conceived and practically demonstrated. The detector has the ability to become electronically reconfigured to operate at any frequency over a wide range. This makes it an excellent candidate for frequency agile radars and other electronic warfare systems based on frequency hopping. The detector exhibits a very low amplitude and phase imbalance, which removes the need for any imbalance compensation technique. The system is designed based on the transversal filtering concept and reconfigurability is achieved via wavelength control in a dispersive fiber. The system operation was demonstrated over a frequency range of 3.5-35 GHz, with a maximum of -32 dB amplitude imbalance.

  18. Open half-volume quadrature transverse electromagnetic coil for high-field magnetic resonance imaging.

    PubMed

    Peshkovsky, A S; Kennan, R P; Fabry, M E; Avdievich, N I

    2005-04-01

    A half-volume quadrature head transverse electromagnetic (TEM) coil has been constructed for 4 T imaging applications. This coil produces a sufficiently large homogeneous B(1) field region for the use as a volume coil. It provides superior transmission efficiency, resulting in significantly lower power deposition, as well as greater sensitivity and improved patient comfort and accessibility compared with conventional full-volume coils. Additionally, this coil suppresses the RF penetration artifact that distorts the RF magnetic field profile and alters the intensity in high-field images recorded with linear surface and volume coils. These advantages make it possible to apply this device as an efficient transmit/receive coil for high-field imaging with a restricted field of view.

  19. Parallel-quadrature phase-shifting digital holographic microscopy using polarization beam splitter

    PubMed Central

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, DVGLN

    2012-01-01

    We present a digital holography microscopy technique based on parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography. PMID:23109732

  20. Parallel-quadrature phase-shifting digital holographic microscopy using polarization beam splitter.

    PubMed

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, Dvgln

    2012-11-01

    We present a digital holography microscopy technique based on parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography.

  1. New quadrature approach based on operational matrix for solving a class of fractional variational problems

    NASA Astrophysics Data System (ADS)

    Ezz-Eldien, S. S.

    2016-07-01

    This manuscript presents a new numerical approach to approximate the solution of a class of fractional variational problems. The presented approach is consisting of using the shifted Legendre orthonormal polynomials as basis functions of the operational matrix of fractional derivatives (described in the Caputo sense) and that of fractional integrals (described in the sense of Riemann-Liouville) with the help of the Legendre-Gauss quadrature formula together with the Lagrange multipliers method for converting such fractional variational problems into easier problems that consist of solving an algebraic system in the unknown coefficients. The convergence of the proposed method is analyzed. Finally, in order to demonstrate the accuracy of the present method, some test problems are introduced with their approximate solutions and comparisons with other numerical approaches.

  2. Multi-component and residual strain field characterization using a quadrature phase shifted EFPI

    SciTech Connect

    Jones, M.E.; Bhatia, V.; Murphy, K.A.; Claus, R.O.; Grace, J.L.; Poland, S.; Tran, T.A.; Greene, J.A.

    1994-12-31

    Fabry-Perot interferometers have been used in fiber optic sensor applications to measure various relative strain and environmental effects in materials and structures. Industrial, commercial, and military applications have all been demonstrated. In this paper the authors present the ability to make absolute measurements using an absolute extrinsic Fabry-Perot interferometer (AEFPI). Performance is demonstrated with a measurement rate of 2 {micro}m/sec. A modified EFPI sensor that is able to distinguish between axial strain and the other strain states is also presented. The quadrature phase shifted extrinsic Fabry-Perot interferometer (QPS/EFPI) takes advantage of two input fibers whose transfer function curves are displaced by one quarter of a complete fringe, thus allowing determination of strain magnitude and direction. A variety of applications are described demonstrating the diverse scope and effectiveness of the EFPI sensors. These applications could benefit from the additional measurement capabilities of the aforementioned sensor designs.

  3. Propagation influences on the performance of a reduced bandwidth quadrature phase shift keyed digital radio system

    NASA Astrophysics Data System (ADS)

    Doble, J. E.

    1984-10-01

    British Telecom is running a field trial of a spectrally efficient (4.2 bits/Hz) reduced bandwidth quadrature phase shift keyed digital radio system for the lower 6 GHz and 4 GHz bands in a part of the UK that is subject to above average multipath activity. Some of the observations made during a two-year period are described together with the improvements made to the antennas and the methods likely to be used in predicting system performance in other locations. The current method of predicting multipath fading is examined and found wanting in its application to digital system planning. An alternative is put forward and an example of its use is given.

  4. An efficient nonclassical quadrature for the calculation of nonresonant nuclear fusion reaction rate coefficients from cross section data

    NASA Astrophysics Data System (ADS)

    Shizgal, Bernie D.

    2016-08-01

    Nonclassical quadratures based on a new set of half-range polynomials, Tn(x) , orthogonal with respect to w(x) =e - x - b /√{ x } for x ∈ [ 0 , ∞) are employed in the efficient calculation of the nuclear fusion reaction rate coefficients from cross section data. The parameter b = B /√{kB T } in the weight function is temperature dependent and B is the Gamow factor. The polynomials Tn(x) satisfy a three term recurrence relation defined by two sets of recurrence coefficients, αn and βn. These recurrence coefficients define in turn the tridiagonal Jacobi matrix whose eigenvalues are the quadrature points and the weights are calculated from the first components of the eigenfunctions. For nonresonant nuclear reactions for which the astrophysical function can be expressed as a lower order polynomial in the relative energy, the convergence of the thermal average of the reactive cross section with this nonclassical quadrature is extremely rapid requiring in many cases 2-4 quadrature points. The results are compared with other libraries of nuclear reaction rate coefficient data reported in the literature.

  5. Optimizing MRI signal-to-noise ratio for quadrature unmatched RF coils: two preamplifiers are better than one.

    PubMed

    Sorgenfrei, B L; Edelstein, W A

    1996-07-01

    Using separate preamplifiers for the two outputs of a quadrature receive coil (and then combining the preamplifier outputs in a quadrature hybrid) provides a better signal-to-noise ratio (SNR) than is obtained by directly combining the quadrature outputs in a hybrid followed by a single preamplifier. The advantage of the two-preamplifier configuration increases when the body coil impedance changes and is no longer matched to 50 ohms. Using 0.4 dB noise figure preamplifiers, theory predicts 1.53, 0.42, 0, 0.42, and 1.53 dB SNR advantage of the two-preamplifier configuration over the one-preamplifier arrangement at body coil impedances of 12.5, 25, 50, 100, and 200 ohms, respectively. Experimental hot/cold resistor noise figure measurements indicate 2.86, 0.65, 0.36, 0.83, and 1.40 dB noise figure advantage for the two preamplifier configuration relative to the one-preamplifier configuration at those impedances. Empirical gains larger than theoretically calculated are attributable to insertion losses of various circuit elements, such as the quadrature hybrid, for the one-preamplifier configuration.

  6. Simultaneous quadrature detection of suppressed-carrier weak-coherent-states using a homodyne optical Costas loop receiver

    NASA Astrophysics Data System (ADS)

    López, J. A.; García, E.; Mendieta, F. J.; Arvizu, A.; Gallion, Phillipe

    2011-08-01

    Weak coherent states (WCS) are being extensively employed in quantum communications and cryptography at telecommunications wavelengths. For these low-photon-number applications, simultaneous field quadrature measurements are frequently required, such as in the detection of multilevel modulations in the communications scenario or in cryptographic applications employing continuous variables. For this task multiport balanced homodyne detection (BHD) structures are employed, based on the splitting of the received field into its (non-commutating) in-phase (I) and quadrature (Q) components and their separate beating with a local oscillator (LO) in two BHD. This allows the simultaneous measurements of the 2 quadratures at the price of an additional noise due to the vacuum fields that leak via the unused ports. These schemes require the proper optical phase synchronization between the LO and the incoming field, which constitutes a challenge for WCS reception, especially for suppressed carrier modulations that are required for power economy. For this task, a Costas loop is implemented for low photon number WCS, with the design of an optimum feedback scheme considering the phase diffusion of WCS generated by semiconductor lasers. We implemented an optical Costas loop at 1550 nm based on polarization splitting of the laser field to detect I and Q quadratures simultaneously. We present results on the performance in phase error and bit error rate and compare with corresponding quantum limit.

  7. Zero-IF and near-zero-IF quadrature demodulators with high tolerance to I-Q imbalance

    NASA Astrophysics Data System (ADS)

    Gu, Jian

    2002-08-01

    This paper deals with quadrature demodulators used for Zero Intermediate Frequency (ZIF) and Near Zero Intermediate frequency (NZIF) receivers. ZIF and NZIF receivers are more sensitive to circuitry mismatch, which causes I-Q imbalance. With IQ-Balancing (IQB) technology, any adverse effect of frequency-dependent I-Q imbalance can be removed and quadrature receivers can have high tolerance to the I-Q imbalance. The paper first provides detailed description of the IQB technology for a simple I-Q network. Then the paper shows that any I-Q operations (ideal or non-ideal) can be described by an I-Q network and that the I-Q network can be described by a set of 2-by-2 matrixes, each of which defines the imbalance condition at a given frequency. As a result, the IQB technology can be applied to the I-Q network to remove any adverse effect. The paper then explains how the IQB technology can be used with a quadrature demodulator for ZIF/NZIF receivers for any modulation schemes. Finally, two application examples are included to show how the proposed quadrature demodulator can make ZIF/NZIF receivers have much higher tolerance to I-Q imbalance. System simulation results are provided for a ZIF receiver for OFDM signals and a NZIF receiver for GMSK signals.

  8. Exponential characteristic spatial quadrature for discrete ordinates radiation transport with rectangular cells

    SciTech Connect

    Minor, B.; Mathews, K.

    1995-07-01

    The exponential characteristic (EC) spatial quadrature for discrete ordinates neutral particle transport previously introduced in slab geometry is extended here to x-y geometry with rectangular cells. The method is derived and compared with current methods. It is similar to the linear characteristic (LC) quadrature (a linear-linear moments method) but differs by assuming an exponential distribution of the scattering source within each cell, S(x) = a exp(bx + cy), whose parameters are rootsolved to match the known (from the previous iteration) spatial average and first moments of the source over the cell. Similarly, EC assumes exponential distributions of flux along cell edges through which particles enter the cell, with parameters chosen to match the average and first moments of flux, as passed from the adjacent, upstream cells (or as determined by boundary conditions). Like the linear adaptive (LA) method, EC is positive and nonlinear. It is more accurate than LA and does not require subdivision of cells. The nonlinearity has not interfered with convergence. The exponential moment functions, which were introduced with the slab geometry method, are extended to arbitrary dimensions (numbers of arguments) and used to avoid numerical ill conditioning. As in slab geometry, the method approaches O({Delta}x{sup 4}) global truncation error on fine-enough meshes, while the error is insensitive to mesh size for coarse meshes. Performance of the method is compared with that of the step characteristic, LC, linear nodal, step adaptive, and LA schemes. The EC method is a strong performer with scattering ratios ranging from 0 to 0.9 (the range tested), particularly so for lower scattering ratios. As in slab geometry, EC is computationally more costly per cell than current methods but can be accurate with very thick cells, leading to increased computational efficiency on appropriate problems.

  9. Dual-mass vibratory rate gyroscope with suppressed translational acceleration response and quadrature-error correction capability

    NASA Technical Reports Server (NTRS)

    Clark, William A. (Inventor); Juneau, Thor N. (Inventor); Lemkin, Mark A. (Inventor); Roessig, Allen W. (Inventor)

    2001-01-01

    A microfabricated vibratory rate gyroscope to measure rotation includes two proof-masses mounted in a suspension system anchored to a substrate. The suspension has two principal modes of compliance, one of which is driven into oscillation. The driven oscillation combined with rotation of the substrate about an axis perpendicular to the substrate results in Coriolis acceleration along the other mode of compliance, the sense-mode. The sense-mode is designed to respond to Coriolis accelerationwhile suppressing the response to translational acceleration. This is accomplished using one or more rigid levers connecting the two proof-masses. The lever allows the proof-masses to move in opposite directions in response to Coriolis acceleration. The invention includes a means for canceling errors, termed quadrature error, due to imperfections in implementation of the sensor. Quadrature-error cancellation utilizes electrostatic forces to cancel out undesired sense-axis motion in phase with drive-mode position.

  10. Photonic vector signal generation employing a novel optical direct-detection in-phase/quadrature-phase upconversion.

    PubMed

    Jiang, Wen-Jr; Lin, Chun-Ting; Ho, Chung-hung; Wei, Chia-Chien; Shih, Po-Tsung; Chen, Jason Jyehong; Chi, Sien

    2010-12-01

    This work demonstrates the feasibility of the generation of an RF direct-detection vector signal using optical in-phase/quadrature-phase (I/Q) upconversion. The advantage of the proposed transmitter is that no electrical mixer is needed to generate the RF signal. Therefore, I/Q data of RF signals are processed at baseband at the transmitter, which is independent of the carrier frequency of the generated RF signal. A 10 Gb/s 16 quadrature amplitude modulation signal is experimentally demonstrated. Following transmission over a 50 km single-mode fiber, the power penalty is negligible. Moreover, I/Q imbalance of the proposed transmitter is studied and compensated by digital signal processing, which is both numerically and experimentally verified.

  11. New formalism for two-photon quantum optics. I - Quadrature phases and squeezed states. II - Mathematical foundation and compact notation

    NASA Technical Reports Server (NTRS)

    Caves, C. M.; Schumaker, B. L.

    1985-01-01

    A new formalism for analyzing two-photon devices, such as parametric amplifiers and phase-conjugate mirrors, is proposed in part I, focusing on the properties and the significance of the quadrature-phase amplitudes and two-mode squeezed states. Time-stationary quasi-probability noise is also detailed for the case of Gaussian noise, and uncertainty principles for the quadrature-phase amplitudes are outlined, as well as some important properties of the two-mode states. Part II establishes a mathematical foundation for the formalism, with introduction of a vector notation for compact representation of two-mode properties. Fundamental unitary operators and special quantum states are also examined with an emphasis on the two-mode squeezed states. The results are applied to a previously studied degenerate limit (epsilon = 0).

  12. Algorithm for the Time-Propagation of the Radial Diffusion Equation Based on a Gaussian Quadrature.

    PubMed

    Gillespie, Dirk

    2015-01-01

    The numerical integration of the time-dependent spherically-symmetric radial diffusion equation from a point source is considered. The flux through the source can vary in time, possibly stochastically based on the concentration produced by the source itself. Fick's one-dimensional diffusion equation is integrated over a time interval by considering a source term and a propagation term. The source term adds new particles during the time interval, while the propagation term diffuses the concentration profile of the previous time step. The integral in the propagation term is evaluated numerically using a combination of a new diffusion-specific Gaussian quadrature and interpolation on a diffusion-specific grid. This attempts to balance accuracy with the least number of points for both integration and interpolation. The theory can also be extended to include a simple reaction-diffusion equation in the limit of high buffer concentrations. The method is unconditionally stable. In fact, not only does it converge for any time step Δt, the method offers one advantage over other methods because Δt can be arbitrarily large; it is solely defined by the timescale on which the flux source turns on and off.

  13. A Quadrature-Free Conservative Level Set RKDG for Simulating Atomization

    NASA Astrophysics Data System (ADS)

    Jibben, Zechariah; Herrmann, Marcus

    2012-11-01

    We present an arbitrary high-order, quadrature-free, Runge-Kutta discontinuous Galerkin (RKDG) method for the solution of the conservative level set equation (Olsson et al., 2007), used for capturing phase interfaces in atomizing multiphase flows. Special care is taken to maintain high-order accuracy in the reinitialization equation, using appropriate slope limiters when necessary and a shared basis across cell interfaces for the diffusive flux. For efficiency, we implement the method in the context of the dual narrow band overset mesh approach of the Refined Level Set Grid method (Herrmann, 2008). The accuracy, consistency, and convergence of the resulting method is demonstrated using the method of manufactured solutions (MMS) and several standard test cases, including Zalesak's disk and columns and spheres in prescribed deformation fields. Using MMS, we demonstrate k + 1 order spatial convergence for k-th order orthonormal Legendre polynomial basis functions. We furthermore show several orders of magnitude improvement in shape and volume errors over traditional WENO based distance function level set methods, and k - 1 order spatial convergence of interfacial curvature using direct neighbor cells only. Supported by Stanford's 2012 CTR Summer Program and NSF grant CBET-1054272.

  14. Recursive, in-place algorithm for the hexagonal orthogonal oriented quadrature image pyramid

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.

    1989-01-01

    Pyramid image transforms have proven useful in image coding and pattern recognition. The hexagonal orthogonal oriented quadrature image pyramid (HOP), transforms an image into a set of orthogonal, oriented, odd and even bandpass subimages. It operates on a hexagonal input lattice and employs seven kernels, each of which occupies a neighborhood consisting of a point and a hexagon of six nearest neighbors. The kernels consist of one lowpass and six bandpass kernels that are orthogonal, self-similar, and localized in space, spatial frequency, orientation, and phase. The kernels are first applied to the image samples to create the first level of the pyramid, then to the lowpass coefficients to create the next level. The resulting pyramid is a compact, efficient image code. Here, a recursive, in-place algorithm for computation of the HOP transform is described. The transform may be regarded as a depth-first traversal of a tree structure. It is shown that the algorithm requires a number of operations that is on the order of the number of pixels.

  15. Security of the differential-quadrature-phase-shift quantum key distribution

    NASA Astrophysics Data System (ADS)

    Kawakami, Shun; Sasaki, Toshihiko; Koashi, Masato

    2016-08-01

    One of the simplest methods for implementing quantum key distribution over fiber-optic communication is the Bennett-Brassard 1984 protocol with phase encoding (PE-BB84 protocol), in which the sender uses phase modulation over double pulses from a laser and the receiver uses a passive delayed interferometer. Using essentially the same setup and by regarding a train of many pulses as a single block, one can carry out the so-called differential-quadrature-phase-shift (DQPS) protocol, which is a variant of differential-phase-shift (DPS) protocols. Here we prove the security of the DQPS protocol based on an adaptation of proof techniques for the BB84 protocol, which inherits the advantages arising from the simplicity of the protocol, such as accommodating the use of threshold detectors and simple off-line calibration methods for the light source. We show that the secure key rate of the DQPS protocol in the proof is eight-thirds as high as the rate of the PE-BB84 protocol.

  16. Digital services using quadrature amplitude modulation (QAM) over CATV analog DWDM system

    NASA Astrophysics Data System (ADS)

    Yeh, JengRong; Selker, Mark D.; Trail, J.; Piehler, David; Levi, Israel

    2000-04-01

    Dense Wavelength Division Multiplexing (DWDM) has recently gained great popularity as it provides a cost effective way to increase the transmission capacity of the existing fiber cable plant. For a long time, Dense WDM was exclusively used for baseband digital applications, predominantly in terrestrial long haul networks and in some cases in metropolitan and enterprise networks. Recently, the performance of DWDM components and frequency-stabilized lasers has substantially improved while the costs have down significantly. This makes a variety of new optical network architectures economically viable. The first commercial 8- wavelength DWDM system designed for Hybrid Fiber Coax networks was reported in 1998. This type of DWDM system utilizes Sub-Carrier Multiplexing (SCM) of Quadrature Amplitude Modulated (QAM) signals to transport IP data digital video broadcast and Video on Demand on ITU grid lightwave carriers. The ability of DWDM to provide scalable transmission capacity in the optical layer with SCM granularity is now considered by many to be the most promising technology for future transport and distribution of broadband multimedia services.

  17. Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature Doppler radar sensor.

    PubMed

    Hu, Wei; Zhao, Zhangyan; Wang, Yunfeng; Zhang, Haiying; Lin, Fujiang

    2014-03-01

    The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%. PMID:24235293

  18. Balancing a retroreflector to minimize rotation errors using a pendulum and quadrature interferometer.

    PubMed

    Niebauer, T M; Constantino, A; Billson, R; Hankla, A; Nelson, P G

    2015-06-20

    A corner-cube retroreflector has the property that the optical path length for a reflected laser beam is insensitive to rotations about a mathematical point called its optical center (OC). This property is exploited in ballistic absolute gravity meters in which a proof mass containing a corner-cube retroreflector is dropped in a vacuum, and its position is accurately determined with a laser interferometer. In order to avoid vertical position errors when the proof mass rotates during free fall, it is important to collocate its center of mass (COM) with the OC of the retroreflector. This is commonly done using a mechanical scale-based balancing procedure, which has limited accuracy due to the difficulty in finding the exact position of the COM and the OC. This paper describes a novel way to achieve the collocation by incorporating the proof mass into a pendulum and using a quadrature interferometer to interrogate its apparent translation in its twist mode. The mismatch between the COM and OC generates a signal in a quiet part of the spectrum where no mechanical resonance exists. This allows us to tune the position of the COM relative to the OC to an accuracy of about 1 μm in all three axes. This provides a way to directly demonstrate that a rotation of the proof mass by several degrees causes an apparent translation in the direction of the laser beam of less than 1 nm. This technique allows an order of magnitude improvement over traditional methods of balancing.

  19. Accurate phase measurements for thick spherical objects using optical quadrature microscopy

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; DiMarzio, Charles A.

    2009-02-01

    In vitro fertilization (IVF) procedures have resulted in the birth of over three million babies since 1978. Yet the live birth rate in the United States was only 34% in 2005, with 32% of the successful pregnancies resulting in multiple births. These multiple pregnancies were directly attributed to the transfer of multiple embryos to increase the probability that a single, healthy embryo was included. Current viability markers used for IVF, such as the cell number, symmetry, size, and fragmentation, are analyzed qualitatively with differential interference contrast (DIC) microscopy. However, this method is not ideal for quantitative measures beyond the 8-cell stage of development because the cells overlap and obstruct the view within and below the cluster of cells. We have developed the phase-subtraction cell-counting method that uses the combination of DIC and optical quadrature microscopy (OQM) to count the number of cells accurately in live mouse embryos beyond the 8-cell stage. We have also created a preliminary analysis to measure the cell symmetry, size, and fragmentation quantitatively by analyzing the relative dry mass from the OQM image in conjunction with the phase-subtraction count. In this paper, we will discuss the characterization of OQM with respect to measuring the phase accurately for spherical samples that are much larger than the depth of field. Once fully characterized and verified with human embryos, this methodology could provide the means for a more accurate method to score embryo viability.

  20. Real-space quadrature: A convenient, efficient representation for multipole expansions

    SciTech Connect

    Rogers, David M.

    2015-02-21

    Multipoles are central to the theory and modeling of polarizable and nonpolarizable molecular electrostatics. This has made a representation in terms of point charges a highly sought after goal, since rotation of multipoles is a bottleneck in molecular dynamics implementations. All known point charge representations are orders of magnitude less efficient than spherical harmonics due to either using too many fixed charge locations or due to nonlinear fitting of fewer charge locations. We present the first complete solution to this problem—completely replacing spherical harmonic basis functions by a dramatically simpler set of weights associated to fixed, discrete points on a sphere. This representation is shown to be space optimal. It reduces the spherical harmonic decomposition of Poisson’s operator to pairwise summations over the point set. As a corollary, we also shows exact quadrature-based formulas for contraction over trace-free supersymmetric 3D tensors. Moreover, multiplication of spherical harmonic basis functions translates to a direct product in this representation.

  1. Noncontact accurate measurement of cardiopulmonary activity using a compact quadrature Doppler radar sensor.

    PubMed

    Hu, Wei; Zhao, Zhangyan; Wang, Yunfeng; Zhang, Haiying; Lin, Fujiang

    2014-03-01

    The designed sensor enables accurate reconstruction of chest-wall movement caused by cardiopulmonary activities, and the algorithm enables estimation of respiration, heartbeat rate, and some indicators of heart rate variability (HRV). In particular, quadrature receiver and arctangent demodulation with calibration are introduced for high linearity representation of chest displacement; 24-bit ADCs with oversampling are adopted for radar baseband acquisition to achieve a high signal resolution; continuous-wavelet filter and ensemble empirical mode decomposition (EEMD) based algorithm are applied for cardio/pulmonary signal recovery and separation so that accurate beat-to-beat interval can be acquired in time domain for HRV analysis. In addition, the wireless sensor is realized and integrated on a printed circuit board compactly. The developed sensor system is successfully tested on both simulated target and human subjects. In simulated target experiments, the baseband signal-to-noise ratio (SNR) is 73.27 dB, high enough for heartbeat detection. The demodulated signal has 0.35% mean squared error, indicating high demodulation linearity. In human subject experiments, the relative error of extracted beat-to-beat intervals ranges from 2.53% to 4.83% compared with electrocardiography (ECG) R-R peak intervals. The sensor provides an accurate analysis for heart rate with the accuracy of 100% for p = 2% and higher than 97% for p = 1%.

  2. An efficient quadrature for 2.5D boundary element calculations

    NASA Astrophysics Data System (ADS)

    Kasess, Christian H.; Kreuzer, Wolfgang; Waubke, Holger

    2016-11-01

    In recent years, the boundary element method has become a widely used tool for calculating the mitigation effects of noise barriers. However, since for large structures calculations in 3D become very inefficient, most of the standard implementations are only in 2D. This means that the noise source is implicitly assumed to be given by a coherent line source, which is not realistic in most cases. By using a Fourier transform with respect to a spatial coordinate along the length of the structure it is possible to reduce the 3D problem to several 2D problems with distinct wavenumbers which allows the simulation of more realistic noise sources and which is typically referred to as 2.5D BEM. To that end, it is necessary to numerically calculate a Fourier-like integral over all the 2D solutions. In this work, an efficient way to calculate this integral is given building on existing approaches using Clenshaw-Curtis-Filon quadrature and demodulation combined with an adaptive order-selection scheme. As BEM calculations are costly, the main focus of the method introduced lies on avoiding too many of these calculations. The efficiency of the method is illustrated using two different examples: a reflecting cylinder and an L-shaped noise barrier.

  3. SOHO-Ulysses Coordinated Studies During the Two Extended Quadratures and the Radial Alignment of 2007-2008

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.

    2007-01-01

    During quadrature, plasma seen on the limb of the Sun, along the radi al direction to Ulysses, by SOHO or STEREO can be sampled in situ as lt later passes Ulysses. A figure shows a coronagraph image, the rad ial towards Ulysses at 58 deg. S. and the SOHO/UVCS slit positions d uring one set of observations. A CME subsequently occurred and passed Ulysses (at 3/4 AU) 15 days later.

  4. Combining optical quadrature and differential interference contrast to facilitate embryonic cell counting with fluorescence imaging for confirmation

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; Newmark, Judith A.; Chang, ChihChing; Brooks, Dana H.; Warner, Carol M.; DiMarzio, Charles A.

    2005-03-01

    The Multifunctional Staring Mode Microscope was developed to permit three modes of imaging for cell counting in mouse embryos: Optical Quadrature, Differential Interference Contrast (DIC), and Fluorescence Imaging. The Optical Quadrature Microscope, consisting of a modified Mach-Zender Interferometer, uses a 632.8 nm laser to measure the amplitude and phase of the signal beam that travels through the embryo. Four cameras, preceded by multiple beamsplitters, are used to read the four interferograms, which are then combined to produce an image of the complex electric field amplitude. The phase of the complex amplitude is then unwrapped using a 2-D phase unwrap algorithm and images of optical path length are produced. To combine the additional modes of DIC and Fluorescence Imaging with the Optical Quadrature Microscope, a 632.8 nm narrow bandpass beamsplitter was placed at the output of the microscope. This allows the laser light to continue through the Mach-Zender while all other wavelengths are reflected at 90 degrees to another camera. This was effective in combining the three modes as the fluorescence wavelength for the Hoechst stain is well below the bandpass window of the beamsplitter. Both live and fixed samples have been successfully imaged in all three modes. Accuracy in cell counting was achieved by using the DIC image for detecting cell boundaries and the Optical Quadrature image for phase mapping to determine where cells overlap. The final results were verified by Hoechst fluorescence imaging to count the individual nuclei. Algorithms are currently being refined so larger cell counts can be done more efficiently.

  5. Numerical performance of AOR methods in solving first order composite closed Newton-Cotes quadrature algebraic equations

    NASA Astrophysics Data System (ADS)

    Muthuvalu, Mohana Sundaram; Aruchunan, Elayaraja; Koh, Wei Sin; Akhir, Mohd Kamalrulzaman Md; Sulaiman, Jumat; Karim, Samsul Ariffin Abdul

    2014-07-01

    In this paper, the application of the Accelerated Over-Relaxation (AOR) iterative method is extended to solve first order composite closed Newton-Cotes quadrature (1-CCNC) algebraic equations arising from second kind linear Fredholm integral equations. The formulation and implementation of the method are also discussed. In addition, numerical results by solving several test problems are included and compared with the conventional iterative methods.

  6. Differential Quadrature and RAYLEIGH RITZ Methods to Determine the Fundamental Frequencies of Simply Supported Rectangular Plates with Linearly Varying Thickness

    NASA Astrophysics Data System (ADS)

    Kukreti, A. R.; Farsa, J.; Bert, C. W.

    1996-01-01

    In this paper, differential quadrature and Rayleigh-Ritz methods are presented for computation of the fundamental frequency of simply supported, homogeneous, isotropic, thin rectangular plates with the thickness tapering linearly in one direction. The complete analytical formulation and solution procedure is presented for both methods. Results obtained by these two methods are compared with available results in the literature and by the finite element method. Effects of the level of discretization, aspect and taper ratios are also presented.

  7. Amplitude and Transverse Quadrature Component Squeezing of Coherent Light in High Q Cavity by Injection of Atoms of Two-Photon Transition

    NASA Technical Reports Server (NTRS)

    Cao, Chang-Qi

    1996-01-01

    The amplitude and transverse quadrature component squeezing of coherent light in high Q cavity by injection of atoms of two-photon transition are studied. The Golubev-Sokolov master equation and generating function approach are utilized to derive the exact variances of photon number and of transverse quadrature component as function of t. The correlation functions and power spectrums of photon number noise and of output photon current noise are also investigated.

  8. The 2011 February 15 Coronal Mass Ejection: Reconciling SOHO and STEREO Observations in Quadrature

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2011-01-01

    The Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO observed a fast halo coronal mass ejection on 2011 February 15. The STEREO spacecraft were in quadrature with SOHO (STEREO-A ahead of Earth by 87 degrees and STEREO-B 94 degrees behind Earth), enabling CME measurement using the three spacecraft. The sky-plane speed measured by SOHO/LASCO is closely related to the expansion speed of the CME, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (V(sub exp) ) and radial speed (V(sub rad)) derived previously from geometrical considerations (Gopalswamy et al. 2009): = V(sub rad) = 1/2 (1 + cot w) V(sub exp), where w is the half width of the CME. We can also measure the Earthward speed of the CME directly from the STEREO measurements. The travel time to Earth predicted from the Earthward speed using the Empirical Shock Arrival model is approximately 12 hours shorter than the actual travel time obtained from in situ measurements at Ll. The primary reason for this discrepancy seems to be the interaction with the two preceding CMEs that slowed down the CME in question. The CME interaction is also confirmed from the radio enhancement observed by Wind/WAVES and STEREO WAVES experiments.

  9. Improving the Accuracy of Quadrature Method Solutions of Fredholm Integral Equations That Arise from Nonlinear Two-Point Boundary Value Problems

    NASA Technical Reports Server (NTRS)

    Sidi, Avram; Pennline, James A.

    1999-01-01

    In this paper we are concerned with high-accuracy quadrature method solutions of nonlinear Fredholm integral equations of the form y(x) = r(x) + definite integral of g(x, t)F(t,y(t))dt with limits between 0 and 1,0 less than or equal to x les than or equal to 1, where the kernel function g(x,t) is continuous, but its partial derivatives have finite jump discontinuities across x = t. Such integral equations arise, e.g., when one applied Green's function techniques to nonlinear two-point boundary value problems of the form y "(x) =f(x,y(x)), 0 less than or equal to x less than or equal to 1, with y(0) = y(sub 0) and y(l) = y(sub l), or other linear boundary conditions. A quadrature method that is especially suitable and that has been employed for such equations is one based on the trepezoidal rule that has a low accuracy. By analyzing the corresponding Euler-Maclaurin expansion, we derive suitable correction terms that we add to the trapezoidal rule, thus obtaining new numerical quadrature formulas of arbitrarily high accuracy that we also use in defining quadrature methods for the integral equations above. We prove an existence and uniqueness theorem for the quadrature method solutions, and show that their accuracy is the same as that of the underlying quadrature formula. The solution of the nonlinear systems resulting from the quadrature methods is achieved through successive approximations whose convergence is also proved. The results are demonstrated with numerical examples.

  10. Improving the Accuracy of Quadrature Method Solutions of Fredholm Integral Equations that Arise from Nonlinear Two-Point Boundary Value Problems

    NASA Technical Reports Server (NTRS)

    Sidi, Avram; Pennline, James A.

    1999-01-01

    In this paper we are concerned with high-accuracy quadrature method solutions of nonlinear Fredholm integral equations of the form y(x) = r(x) + integral(0 to 1) g(x,t) F(t, y(t)) dt, 0 less than or equal to x less than or equal to 1, where the kernel function g(x,t) is continuous, but its partial derivatives have finite jump discontinuities across x = t. Such integrals equations arise, e.g., when one applies Green's function techniques to nonlinear two-point boundary value problems of the form U''(x) = f(x,y(x)), 0 less than or equal to x less than or equal to 1, with y(0) = y(sub 0) and g(l) = y(sub 1), or other linear boundary conditions. A quadrature method that is especially suitable and that has been employed for such equations is one based on the trapezoidal rule that has a low accuracy. By analyzing the corresponding Euler-Maclaurin expansion, we derive suitable correction terms that we add to the trapezoidal thus obtaining new numerical quadrature formulas of arbitrarily high accuracy that we also use in defining quadrature methods for the integral equations above. We prove an existence and uniqueness theorem for the quadrature method solutions, and show that their accuracy is the same as that of the underlying quadrature formula. The solution of the nonlinear systems resulting from the quadrature methods is achieved through successive approximations whose convergence is also proved. The results are demonstrated with numerical examples.

  11. SOHO-Ulysses Coordinated Studies During the Two Extended Quadratures and the Alignment of 2007-2008

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Poletto, G.

    2007-01-01

    During SOHO-Sun-Ulysses quadratures the geometry of the configuration makes it possible to sample "in situ" the plasma parcels that are remotely observed in the corona. Although the quadrature position occurs at a well defined instant in time, we typically take data while Ulysses is within +/- 5 degrees of the limb, with the understanding that plasma sampled by Ulysses over this time interval can all be traced to its source in the corona. The relative positions of SOHO and Ulysses in winter 2007 (19 Dec 2006-28 May 2007) are unusual: the SOHO-Sun-Ulysses included angle is always between 85 and 95 degrees - the quadrature lasts for 5 months! This provides an opportunity for extended observations of specific observing objectives. In addition, in summer 2007, Ulysses (at 1.34 AU) is in near-radial alignment with Earth/ACE/Wind and SOHO, allowing us to analyze radial gradients and propagation in the solar wind and inner heliosphere. Our own quadrature campaigns rely heavily on LASCO and UVCS coronal observations: LASCO giving the overall context above 2 solar radii while the UVCS spectrograph acquired data from - 1.5 to, typically, 4-5 solar radii. In the past, coronal parameters have been derived from data acquired by these two experiments and compared with "in situ" data of Ulysses' SWOOPS and SWICS. Data from other experiments like EIT, CDS, SUMER, Sac Peak Fe XIV maps, magnetic field maps from the Wilcox solar magnetograph, MLSO, from MDI, and from the Ulysses magnetograph experiment have been, and will be, used to complement LASCO/UVCS/SWOOPS and SWICS data. We anticipate that observations by ACE/WIND/STEREO/Hinode and other missions will be relevant as well. During the IHY campaigns, Ulysses will be 52-80 degrees south in winter 2007, near sunspot minimum. Hence, our own scientific objective will be to sample high speed wind or regions of transition between slow and fast wind. This might be a very interesting situation - not met in previous quadratures - allowing

  12. Long-Term Quadrature Light Variability in Early Type Interacting Binary Systems

    NASA Astrophysics Data System (ADS)

    Peters, Geraldine J.; Wilson, R. E.; Vaccaro, T. R.

    2014-01-01

    Four years of Kepler observations have revealed a phenomenon in the light curves of short-period Algol-type eclipsing binaries that has never been reported from ground-based photometry. These systems display unequal brightness at their quadrature phases that numerically reverses over a time scale of about 100-400 days. We call these systems L/T (leading hemisphere/ trailing hemisphere) variables. Twenty-one such systems have so far been identified in the Kepler database and at least three classes of L/T behavior have been identified. The prototype is WX Draconis (A8V + K0IV, P=1.80 d) which shows L/ T light variations of 2-3%. The primary is a delta Scuti star with a dominant pulsation period of 41 m. The Kepler light curves are being analyzed with the 2013 version of the Wilson-Devinney (WD) program that includes major improvements in modeling star spots (i.e. spot motions due to drift and stellar rotation and spot growth and decay). Preliminary analysis of the WX Dra data suggests that the L/T variability can be fit with either an accretion hot spot on the primary (T = 2.3 T_phot) that jumps in longitude or a magnetic cool spotted region on the secondary. If the latter model is correct the dark region must occupy at least 20% of the surface of the facing hemisphere of the secondary if it is completely black, or a larger area if not completely black. In both hot and cool spot scenarios magnetic fields must play a role in the activity. Echelle spectra were recently secured with the KPNO 4-m telescope to determine the mass ratios of the L/T systems and their spectral types. This information will allow us to assess whether the hot or cool spot model explains the L/T activity. Progress toward this goal will be presented. Support from NASA grants NNX11AC78G and NNX12AE44G and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

  13. Large eddy simulations of coal jet flame ignition using the direct quadrature method of moments

    NASA Astrophysics Data System (ADS)

    Pedel, Julien

    The Direct Quadrature Method of Moments (DQMOM) was implemented in the Large Eddy Simulation (LES) tool ARCHES to model coal particles. LES coupled with DQMOM was first applied to nonreacting particle-laden turbulent jets. Simulation results were compared to experimental data and accurately modeled a wide range of particle behaviors, such as particle jet waviness, spreading, break up, particle clustering and segregation, in different configurations. Simulations also accurately predicted the mean axial velocity along the centerline for both the gas phase and the solid phase, thus demonstrating the validity of the approach to model particles in turbulent flows. LES was then applied to the prediction of pulverized coal flame ignition. The stability of an oxy-coal flame as a function of changing primary gas composition (CO2 and O2) was first investigated. Flame stability was measured using optical measurements of the flame standoff distance in a 40 kW pilot facility. Large Eddy Simulations (LES) of the facility provided valuable insight into the experimentally observed data and the importance of factors such as heterogeneous reactions, radiation or wall temperature. The effects of three parameters on the flame stand-off distance were studied and simulation predictions were compared to experimental data using the data collaboration method. An additional validation study of the ARCHES LES tool was then performed on an air-fired pulverized coal jet flame ignited by a preheated gas flow. The simulation results were compared qualitatively and quantitatively to experimental observations for different inlet stoichiometric ratios. LES simulations were able to capture the various combustion regimes observed during flame ignition and to accurately model the flame stand-off distance sensitivity to the stoichiometric ratio. Gas temperature and coal burnout predictions were also examined and showed good agreement with experimental data. Overall, this research shows that high

  14. Quasi-Periodic Long-Term Quadrature Light Variability in Early Type Interacting Binary Systems

    NASA Astrophysics Data System (ADS)

    Peters, Geraldine Joan

    2015-08-01

    Four years of Kepler observations have revealed a class of Algol-type binaries in which the relative brightness of the quadrature light varies from > 1 to <1 on a time scale of about 100-400 days. The behavior pattern is quasi-periodic. We call these systems L/T (leading hemisphere/ trailing hemisphere) variables. Although L/T inequality in eclipsing binaries has been noted from ground-based photometry by several observers since the early 1950s, the regular or quasi-regular switching between maxima is new. Twenty L/T systems have so far been found in the Kepler database and at least three classes of L/T behavior have been identified. In this presentation I will give an update on the L/T phenomenon gleaned from the Kepler and K2 databases. The Kepler and K2 light curves are being analyzed with the 2015 version of the Wilson-Devinney (WD) program that includes major improvements in modeling star spots (i.e. spot motions due to drift and stellar rotation and spot growth and decay). The prototype L/T variable is WX Draconis (A8V + K0IV, P=1.80 d) which shows L/ T light variations of 2-3%. The primary is a delta Scuti star with a dominant pulsation period of 41 m. Preliminary analysis of the WX Dra data suggests that the L/T variability can be fit with either an accretion hot spot on the primary (T = 2.3 Tphot) that jumps in longitude or a magnetic cool spotted region on the secondary. If the latter model is correct the dark region must occupy at least 20% of the surface of the facing hemisphere of the secondary if it is completely black, or a larger area if not completely black. In both hot and cool spot scenarios magnetic fields must play a role in the activity. Support from NASA grants NNX11AC78G and NNX12AE44G and USC’s Women in Science and Engineering (WiSE) program is greatly appreciated.

  15. I/Q reversal phenomena in 4-phase modified Costas Loops. [in-phase and quadrature outputs of unbalanced QPSK

    NASA Technical Reports Server (NTRS)

    Weinberg, A.

    1985-01-01

    A method for predicting the occurrence of I/Q reversals in unbalanced QPSK 4-phase modified Costas Loops is discussed. Potential causes for the reversal of in-phase and quadrature outputs of the unbalanced QPSK demodulator during acquisition and tracking are studied. The design of the unbalance QPSK demodulator and loop characteristics are described. The effect of an anomalous condition during a transient interval or demod/remod operation on data source output is examined. Filtering and hard-limiting effects, and the demodulator loop S-curve stability during tracking are evaluated.

  16. Quadrature RF Coil for In Vivo Brain MRI of a Macaque Monkey in a Stereotaxic Head Frame

    PubMed Central

    ROOPNARIANE, COLIN A.; RYU, YEUN-CHUL; TOFIGHI, MOHAMMAD-REZA; MILLER, PATTI A.; OH, SUKHOON; WANG, JIANLI; PARK, BU SIK; ANSEL, LUKAS; LIEU, CHRISTOPHER A.; SUBRAMANIAN, THYAGARAJAN; YANG, QING X.; COLLINS, CHRISTOPHER M.

    2012-01-01

    We present a quadrature volume coil designed for brain imaging of a macaque monkey fixed in a sphinx position (facing down the bore) within a stereotactic frame at 3 T, where the position of the monkey and presence of the frame preclude use of existing coils. Requirements include the ability to position and remove the coil without disturbing the position of the monkey in the frame. A saddle coil and a solenoid were combined on a modified cylindrical former and connected in quadrature as to produce a homogeneous circularly polarized field throughout the brain. To allow the loops of the saddle coil to encompass the ear posts, partial disassembly and reassembly were facilitated by embedding pin and socket contacts into separate pieces of the former. Coil design included simulation of the electromagnetic fields for the coil containing a 3D model of a monkey’s head. The resulting coil produced adequate homogeneity and signal-to-noise ratio throughout the brain. PMID:22611340

  17. Exponential-characteristic spatial quadrature for discrete-ordinates neutral-particle transport in slab geometry. Master's thesis

    SciTech Connect

    Sjoden, G.E.

    1992-03-01

    A new discrete ordinates spatial quadrature scheme is presented for solving neutral particle transport problems. This new scheme, called the exponential characteristic method, is developed here in slab geometry with isotropic scattering. This method uses a characteristic integration of the Boltzmann transport equation with an exponential function as the assumed from of the source distribution, continuous across each spatial cell. The exponential source function is constructed to globally conserve zeroth and first spatial source moments and is non-negative. Characteristic integration ensures non-negative fluxes and flux moments. Numerical testing indicates that convergence of the exponential characteristic scheme is fourth order in the limit of vanishingly thin cells. Highly accurate solutions to optically thick problems can result using this scheme with very coarse meshes. Comparing accuracy and computational cost with existing spatial quadrature schemes (diamond difference, linear discontinuous, linear characteristic, linear adaptive, etc.), the exponential characteristic scheme typically performed best. This scheme is expected to be expandable to two dimensions in a straight forward manner. Due to the high accuracies achievable using coarse meshes, this scheme may allow researchers to obtain solutions to transport problems once thought too large or too difficult to be adequately solved conventional computer systems.

  18. Adaptive Square-Root Cubature-Quadrature Kalman Particle Filter for satellite attitude determination using vector observations

    NASA Astrophysics Data System (ADS)

    Kiani, Maryam; Pourtakdoust, Seid H.

    2014-12-01

    A novel algorithm is presented in this study for estimation of spacecraft's attitudes and angular rates from vector observations. In this regard, a new cubature-quadrature particle filter (CQPF) is initially developed that uses the Square-Root Cubature-Quadrature Kalman Filter (SR-CQKF) to generate the importance proposal distribution. The developed CQPF scheme avoids the basic limitation of particle filter (PF) with regards to counting the new measurements. Subsequently, CQPF is enhanced to adjust the sample size at every time step utilizing the idea of confidence intervals, thus improving the efficiency and accuracy of the newly proposed adaptive CQPF (ACQPF). In addition, application of the q-method for filter initialization has intensified the computation burden as well. The current study also applies ACQPF to the problem of attitude estimation of a low Earth orbit (LEO) satellite. For this purpose, the undertaken satellite is equipped with a three-axis magnetometer (TAM) as well as a sun sensor pack that provide noisy geomagnetic field data and Sun direction measurements, respectively. The results and performance of the proposed filter are investigated and compared with those of the extended Kalman filter (EKF) and the standard particle filter (PF) utilizing a Monte Carlo simulation. The comparison demonstrates the viability and the accuracy of the proposed nonlinear estimator.

  19. A new 16-ary modulation for super-Nyquist-WDM systems: Dual-polarized quadrature duoquaternary (DP-QDQ) modulation

    NASA Astrophysics Data System (ADS)

    Chang, Chun; Huang, Benxiong; Xu, Zhengguang; Li, Bin

    2015-12-01

    A partial-response-pulse-shaped 16-ary quadrature amplitude modulation (16QAM) format called quadrature duoquaternary (QDQ) modulation, which can achieve higher spectral efficiency than Nyquist-pulse-shaped 16QAM and realize super-Nyquist wavelength-division-multiplexing (WDM) transmission, is proposed. The dual-polarized QDQ (DP-QDQ) modulation principle and coherent reception based on digital signal processing (DSP) are presented. The performance of the DP-QDQ scheme is investigated in 32-GBaud super-Nyquist-WDM systems by simulation. The simulation results show that DP-QDQ has only a 1.3 dB optical-signal-to-noise-ratio (OSNR) penalty for the 28-GHz-spaced 5-channel super-Nyquist-WDM case relative to the single-channel case. Compared with Nyquist-pulse-shaped 16QAM, DP-QDQ not only has a higher spectral efficiency, but also a lower sensitivity to sampling time error and a better dispersion tolerance. The 28-GHz-spaced 5-channel super-Nyquist-WDM DP-QDQ system can successfully implement 1520-km transmission at the forward-error-correction (FEC) bit-error-rate (BER) requirements.

  20. Planar quadrature RF transceiver design using common-mode differential-mode (CMDM) transmission line method for 7T MR imaging.

    PubMed

    Li, Ye; Yu, Baiying; Pang, Yong; Vigneron, Daniel B; Zhang, Xiaoliang

    2013-01-01

    The use of quadrature RF magnetic fields has been demonstrated to be an efficient method to reduce transmit power and to increase the signal-to-noise (SNR) in magnetic resonance (MR) imaging. The goal of this project was to develop a new method using the common-mode and differential-mode (CMDM) technique for compact, planar, distributed-element quadrature transmit/receive resonators for MR signal excitation and detection and to investigate its performance for MR imaging, particularly, at ultrahigh magnetic fields. A prototype resonator based on CMDM method implemented by using microstrip transmission line was designed and fabricated for 7T imaging. Both the common mode (CM) and the differential mode (DM) of the resonator were tuned and matched at 298MHz independently. Numerical electromagnetic simulation was performed to verify the orthogonal B1 field direction of the two modes of the CMDM resonator. Both workbench tests and MR imaging experiments were carried out to evaluate the performance. The intrinsic decoupling between the two modes of the CMDM resonator was demonstrated by the bench test, showing a better than -36 dB transmission coefficient between the two modes at resonance frequency. The MR images acquired by using each mode and the images combined in quadrature showed that the CM and DM of the proposed resonator provided similar B1 coverage and achieved SNR improvement in the entire region of interest. The simulation and experimental results demonstrate that the proposed CMDM method with distributed-element transmission line technique is a feasible and efficient technique for planar quadrature RF coil design at ultrahigh fields, providing intrinsic decoupling between two quadrature channels and high frequency capability. Due to its simple and compact geometry and easy implementation of decoupling methods, the CMDM quadrature resonator can possibly be a good candidate for design blocks in multichannel RF coil arrays.

  1. Experimental investigation of 84-Gb/s and 112-Gb/s polarization-switched quadrature phase-shift keying signals.

    PubMed

    Fischer, Johannes Karl; Molle, Lutz; Nölle, Markus; Gross, Dirk-Daniel; Schmidt-Langhorst, Carsten; Schubert, Colja

    2011-12-12

    We experimentally investigate 28-GBd (84-Gb/s) and 37.3-GBd (112-Gb/s) polarization-switched quadrature phase-shift keying (PS-QPSK) signals. In single-channel transmission experiments over up to 12500 km ultra large effective area fiber, we compare their performance to that of polarization-division multiplexing quadrature phase-shift keying (PDM-QPSK) signals at the same bit rates. The experimental results show that PS-QPSK not only benefits from its better sensitivity but also offers an increased tolerance to intra-channel nonlinearities. PMID:22274086

  2. Multi-spatial-mode single-beam quadrature squeezed states of light from four-wave mixing in hot rubidium vapor.

    PubMed

    Corzo, Neil; Marino, Alberto M; Jones, Kevin M; Lett, Paul D

    2011-10-24

    We present experimental results on the generation of multi-spatial-mode, single-beam, quadrature squeezed light using four-wave mixing in hot Rb vapor. Squeezing and phase-sensitive deamplification are observed over a range of powers and detunings near the (85)Rb D1 atomic transition. We observe -3 dB of vacuum quadrature squeezing, comparable to the best single-spatial mode results previously reported using atomic vapors, however, produced here in multiple spatial modes. We confirm that the squeezing is present in more than one transverse mode by studying the spatial distribution of the noise properties of the field.

  3. Experimental investigation of 84-Gb/s and 112-Gb/s polarization-switched quadrature phase-shift keying signals.

    PubMed

    Fischer, Johannes Karl; Molle, Lutz; Nölle, Markus; Gross, Dirk-Daniel; Schmidt-Langhorst, Carsten; Schubert, Colja

    2011-12-12

    We experimentally investigate 28-GBd (84-Gb/s) and 37.3-GBd (112-Gb/s) polarization-switched quadrature phase-shift keying (PS-QPSK) signals. In single-channel transmission experiments over up to 12500 km ultra large effective area fiber, we compare their performance to that of polarization-division multiplexing quadrature phase-shift keying (PDM-QPSK) signals at the same bit rates. The experimental results show that PS-QPSK not only benefits from its better sensitivity but also offers an increased tolerance to intra-channel nonlinearities.

  4. Wide and Narrow CMEs and Their Source Explosions Observed at the Spring 2003 SOHO-Sun-Ulysses Quadrature

    NASA Technical Reports Server (NTRS)

    Suess, Steven; Corti, G.; Poletto, G.; Sterling, A.; Moore, R.

    2006-01-01

    At the time of the spring 2003 Ulysses-SOHO-Sun quadrature, Ulysses was off the East limb of the Sun at 14.5 degrees north latitude and 4.91 AU. LASCO/C2 images show small transient events that originated from near the limb on May 25, 26 and 27 in the north-east quadrant, along with a large Coronal Mass Ejection (CME) that originated from an active region near disk center on May 26. Ulysses data bear clear signatures of the large CME, specifically including an enhanced abundance of highly ionized Fe. SOHO/UVCS spectra at 1.75 solar radii, near the radial direction to Ulysses, give no evidence of emission from high temperature lines, even for the large CME: instead, for the small events, occasional transient high emission in cool lines was observed, such as the CIII 977 Angstrom line usually absent at coronal levels. Each of these events lasted ca. 1 hour or less and never affected lines from ions forming above ca. 106K. Compact eruptions in Helium 304 Angstrom EIT images, related to the small UVCS transients, were observed at the limb of the Sun over the same period. At least one of these surge events produced a narrow CME observed in LASCO/C2. Most probably all these events are compact magnetic explosions (surges/jets, from around a small island of included polarity) which ejected cool material from lower levels. Ulysses data have been analyzed to find evidence of the cool, narrow CME events, but none or little was found. This puzzling scenario, where events seen by UVCS have no in situ counterparts and vice versa, can be partially explained once the region where the large CME originated is recognized as being at the center of the solar disk so that the CME material was actually much further from the Sun than the 1.7 Rsun height of the UVCS slit off the limb. Conversely, the narrow events may simply have missed Ulysses or been too brief for reliable signatures in composition and ionization state. A basic feature demonstrated by these observations is that large

  5. Ultrasonic study of adhesive bond quality at a steel-to-rubber interface by using quadrature phase detection techniques

    NASA Technical Reports Server (NTRS)

    Smith, A. C.; Yang, H.

    1989-01-01

    The quadrature phase detection technique was used to simultaneously monitor the phase and amplitude of a toneburst signal normally reflected from an adhesively bonded steel-to-rubber interface. The measured phase was found to show a positive shift for all bonded samples with respect to the disbonded state - the phase shift being larger for samples with weaker bonds, as manifested by smaller values of applied tensile loads at failure. A model calculation, which incorporates the concept of interfacial strength into the usual problem of wave propagation in multilayered media, was used to deduce a bond-quality parameter from an experimentally measured phase shift. This bond-quality parameter was found to be correlated with the tensile strength of the adhesive bonds at failure loads.

  6. Exponential characteristic spatial quadrature for discrete ordinates neutral particle transport in two-dimensional cartesian coordinates. Doctoral thesis

    SciTech Connect

    Minor, B.M.

    1993-09-01

    The exponential characteristic spatial quadrature for discrete ordinates neutral particle transport with rectangular cells is developed. Numerical problems arising in the derivation required the development of exponential moment functions. These functions are used to remove indeterminant forms which can cause catastrophic cancellations. The EC method is positive and nonlinear. It conserves particles and satisfies first moment balance. Comparisons of the EC method's performance to other methods in optically thin and thick spatial cells were performed. For optically thin cells, the EC method was shown to converge to the correct answer, with third order truncation error in the thin cell limit. In deep penetration problems, the EC method attained its highest computational efficiencies compared to the other methods. For all the deep penetration problems examined, the number of spatial cells required by the EC method to attain a desired accuracy was less than the other methods.... Mathematics functions, Nuclear radiation, Nuclear engineering, Radiation attenuation, Radiation shielding, Transport theory, Radiation transport.

  7. Complex linear minimum mean-squared-error equalization of spatially quadrature-amplitude-modulated signals in holographic data storage

    NASA Astrophysics Data System (ADS)

    Sato, Takanori; Kanno, Kazutaka; Bunsen, Masatoshi

    2016-09-01

    We applied complex linear minimum mean-squared-error equalization to spatially quadrature-amplitude-modulated signals in holographic data storage (HDS). The equalization technique can improve dispersion in constellation outputs due to intersymbol interference. We confirm the effectiveness of the equalization technique in numerical simulations and basic optical experiments. Our numerical results have shown that intersymbol interference of a retrieved signal in a HDS system can be improved by using the equalization technique. In our experiments, a mean squared error (MSE), which indicates the deviation from an ideal signal, has been used for quantitatively evaluating the dispersion of equalized signals. Our equalization technique has been able to improve the MSE. However, symbols in the equalized signal have remained inseparable. To further improve the MSE and make the symbols separable, reducing errors in repeated measurements is our future task.

  8. Two-wavelength quadrature multipoint detection of partial discharge in power transformers using fiber Fabry-Perot acoustic sensors

    NASA Astrophysics Data System (ADS)

    Dong, Bo; Han, Ming; Wang, Anbo

    2012-06-01

    A reliable and low-cost two-wavelength quadrature interrogating method has been developed to demodulate optical signals from diaphragm-based Fabry-Perot interferometric fiber optic sensors for multipoint partial discharge detection in power transformers. Commercial available fused-silica parts (a wafer, a fiber ferrule, and a mating sleeve) and a cleaved optical single mode fiber were bonded together to form an extrinsic Fabry-Perot acoustic sensor. Two lasers with center wavelengths separated by a quarter of the period of sensor interference fringes were used to probe acousticwave- induced diaphragm vibration. A coarse wavelength-division multiplexing (CWDM) add/drop multiplexer was used to separate the reflected two wavelengths before two photo detectors. Optical couplers were used to distribute mixed laser light to each sensor-detector module for multiplexing purpose. Sensor structure, detection system design and experiment results are presented.

  9. Quadrature Rotating-Frame Gradient Fields for Ultra-Low FieldNuclear Magnetic Resonance and Imaging

    SciTech Connect

    Bouchard, Louis-Serge

    2005-12-30

    Magnetic resonance imaging (MRI) in very low fields isfundamentally limited by untruncated concomitant gradients which causesevere distortions in image acquisition and volume selection if thegradient fields are strong compared to the static field. In this paper,it is shown that gradient fields oscillating in quadrature can be usedfor spatial encoding in low fields and provide substantial improvementsover conventional encoding methods using static gradients. In particular,cases where the gradient field is comparable to or higher than theexternal field, Gmax/B0>1, are examined. It is shown thatundistorted slice selection and image encoding is possible because ofsmaller geometric phase errors introduced during cyclic motions of theHamiltonian. In the low field limit (Gmax/B_0 ->infinity) sliceselection is achieved with a combination of soft pulse segments and acoherent train of hard pulses to average out concomitant fields over thefast scale of the rf Hamiltonian.

  10. Performance analysis of a swept-source optical coherence tomography system with a quadrature interferometer and optical amplification

    NASA Astrophysics Data System (ADS)

    Mao, Youxin; Flueraru, Costel; Chang, Shoude; Popescu, Dan P.; Sowa, Michael G.

    2011-05-01

    A performance analysis of signal to noise ratio for an optical coherence tomography system with quadrature detection and a semiconductor optical amplifier in the sample arm is discussed. The results are compared and discussed in relation to a conventional OCT system (without optical amplification). An increase of the signal to noise ratio up to 14 dB at a depth of 0.5 mm is obtained compared to the system without the optical amplifier. Overall, an improvement was demonstrated for signal coming from deeper regions within the samples. Arterial plaque from a myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbit is visualized and characterized using this system. Improvement of signal to noise ratio increases the penetration depth possible for OCT images, from 1 mm to 2 mm within the vessel wall of an artery. Preliminary results show that vulnerable plaque with fibrous cap, macrophage accumulations and calcification in the arterial tissue are measurable with this OCT system.

  11. An efficient approach to study the pulsatile blood flow in femoral and coronary arteries by Differential Quadrature Method

    NASA Astrophysics Data System (ADS)

    Ghasemi, Seiyed E.; Hatami, M.; Hatami, J.; Sahebi, S. A. R.; Ganji, D. D.

    2016-02-01

    In this paper, flow analysis for a non-Newtonian third grade blood in coronary and femoral arteries is simulated numerically. Blood is considered as the third grade non-Newtonian fluid under periodic body acceleration motion and pulsatile pressure gradient. Differential Quadrature Method (DQM) and Crank Nicholson Method (CNM) are used to solve the Partial Differential Equation (PDE) governing equation by which a good agreement between them was observed in the results. The influences of some physical parameters such as amplitude, lead angle and body acceleration frequency on non-dimensional velocity and profiles are considered. For instance, the results show that increasing the amplitude, Ag, and reducing the lead angle of body acceleration, ϕ, make higher velocity profiles in the center line of both arteries.

  12. An analytic method to account for drag in the Vinti satellite theory. [computer program using quadrature algorithm

    NASA Technical Reports Server (NTRS)

    Watson, J. S.; Mistretta, G. D.; Bonavito, N. L.

    1975-01-01

    A quadrature algorithm is presented which employs analytical expressions for the variations of satellite orbital elements caused by air drag. The Hamiltonian is formally preserved and the Jacobi constants of the motion are advanced with time through the variational equations. The atmospheric density profile is written as a fitted exponential function of the eccentric anomaly, which adheres to tabulated data at all altitudes and simultaneously reduces the variational equations to definite integrals with closed form evaluations, whose limits are in terms of the eccentric anomaly. Results are given for two intense air drag satellites and indicate that the satellite ephemerides produced by this method in conjunction with the Vinti program are of very high accuracy.

  13. Quadrature laser interferometer for in-line thickness measurement of glass panels using a current modulation technique.

    PubMed

    Kim, Jong-Ahn; Kang, Chu-Shik; Eom, Tae Bong; Jin, Jonghan; Suh, Ho Suhng; Kim, Jae Wan

    2014-07-10

    A thickness measurement system is proposed for in-line inspection of thickness variation of flat glass panels. Multi-reflection on the surfaces of glass panel generates an interference signal whose phase is proportional to the thickness of the glass panel. For accurate and stable calculation of the phase value, we obtain quadrature interference signals using a current modulation technique. The proposed system can measure a thickness profile with high speed and nanometric resolution, and obtain higher accuracy through real-time nonlinear error compensation. The thickness profile, measured by a transmissive-type experimental setup, coincided with a comparative result obtained using a contact-type thickness measurement system within the range of ±40  nm. The standard deviations of the measured thickness profiles and their waviness components were less than 3 nm with a scanning speed of 300  mm/s.

  14. Validity of Using Two Numerical Analysis Techniques To Estimate Item and Ability Parameters via MMLE: Gauss-Hermite Quadrature Formula and Mislevy's Histogram Solution.

    ERIC Educational Resources Information Center

    Seong, Tae-Je

    The similarity of item and ability parameter estimations was investigated using two numerical analysis techniques via marginal maximum likelihood estimation (MMLE) with a large simulated data set (n=1,000 examinees) and changing the number of quadrature points. MMLE estimation uses a numerical analysis technique to integrate examinees' abilities…

  15. Relationship Between the Expansion Speed and Radial Speed of CMEs Confirmed Using Quadrature Observations from SOHO and STEREO

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Makela, Pertti; Yashiro, Seiji

    2011-01-01

    It is difficult to measure the true speed of Earth-directed CMEs from a coronagraph along the Sun-Earth line because of the occulting disk. However, the expansion speed (the speed with which the CME appears to spread in the sky plane) can be measured by such coronagraph. In order to convert the expansion speed to radial speed (which is important for space weather applications) one can use empirical relationship between the two that assumes an average width for all CMEs. If we have the width information from quadrature observations, we can confirm the relationship between expansion and radial speeds derived by Gopalswamy et al. (2009, CEAB, 33, 115,2009). The STEREO spacecraft were in quadrature with SOHO (STEREO-A ahead of Earth by 87 and STEREO-B 94 behind Earth) on 2011 February 15, when a fast Earth-directed CME occurred. The CME was observed as a halo by the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The sky-plane speed was measured by SOHO/LASCO as the expansion speed, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp ) and radial speed (Vrad ) derived previously from geometrical considerations (Gopalswamy et al. 2009): Vrad = 1/2 (1 + cot w) Vexp, where w is the half width of the CME. STEREO-B images of the CME, we found that CME had a full width of 75 degrees, so w = 37.5 degrees. This gives the relation as Vrad = 1.15 Vexp. From LASCO observations, we measured Vexp = 897 km/s, so we get the radial speed as 1033 km/s. Direct measurement of radial speed from STEREO gives 945 km/s (STEREO-A) and 1057 km/s (STEREO-B). These numbers are different only by 2.3% and 8.5% (for STEREO-A and STEREO-B, respectively) from the computed value.

  16. Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

    NASA Technical Reports Server (NTRS)

    Wang, C.-W.; Stark, W.

    2005-01-01

    This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

  17. High-resolution coherence domain reflectometry using 1.55 μm supercontinuum source and quadrature spectral detection

    NASA Astrophysics Data System (ADS)

    Smith, Elwyn; Wada, Naoya; Chujo, Wataru; Sampson, David D.

    2002-06-01

    High-power ultra-broadband sources such as a supercontinuum are very attractive in optical coherence tomography (OCT) and optical coherence-domain reflectometry (OCDR) due to their very high resolution potential. However, the large and extensive coherence-function sidelobes typical of such sources preclude their use in conventional OCDR and OCT systems. In addition, device or sample dispersion over such broad bandwidths may also significantly limit the achievable performance. Here we describe a novel experiment using a supercontinuum source with a static Michelson interferometer to perform OCDR at 1.55micrometers . Quadrature spectral detection is used to maximize the scanning range and to allow direct compensation for both the undesirable spectral shape of the source and for the dispersion in the system. Such a non-scanning-interferometer approach is an interesting possible alternative for very broadband, ultra-high resolution OCT systems. We demonstrate that an otherwise obscured small reflection next to a large reflection can be revealed by appropriately weighting the data to reshape the supercontinuum spectrum and compensate for dispersion. Significant reduction of the supercontinuum coherence function sidelobes is achieved, and a resolution in air of 7micrometers (FWHM) is obtained, or less than 5micrometers in media of refractive index 1.45.

  18. Quadrature--based moment closures for non--equilibrium flows: hard--spheres collisions and approach to equilibrium

    NASA Astrophysics Data System (ADS)

    Icardi, Matteo; Asinari, Pietro; Marchisio, Daniele; Izquierdo, Salvador; Fox, Rodney

    2011-11-01

    Recently the Quadrature Method of Moments (QMOM) has been extended to solve several kinetic equations, in particular for gas-particle flows and rarefied gases. This method is usually coupled with simplified linear models for particle collisions. In this work QMOM is tested as a closure for the dynamics of high-order moments with a more realistic collision model namely the hard-spheres model in the Homogeneous Isotropic Boltzmann Equation. The behavior of QMOM far away and approaching the equilibrium is studied. Results are compared to other techniques such as the Lattice-Boltzmann (LBM) and the Grad's expansion (GM) methods. Comparison with a more accurate and computationally expensive model, based on the Discrete Velocity Method (DVM), is also carried out. Our results show that QMOM describes very well the evolution when it is far away from equilibrium, without the drawbacks of the GM and LBM or the computational costs of DVM but it is not able to accurately reproduce the equilibrium and the dynamics close to it. Corrections to cure this behavior are proposed and tested.

  19. Quadrature-based moment closures for non-equilibrium flows: Hard-sphere collisions and approach to equilibrium

    NASA Astrophysics Data System (ADS)

    Icardi, M.; Asinari, P.; Marchisio, D. L.; Izquierdo, S.; Fox, R. O.

    2012-08-01

    Recently the Quadrature Method of Moments (QMOM) has been extended to solve several kinetic equations, in particular for gas-particle flows and rarefied gases in which the non-equilibrium effects can be important. In this work QMOM is tested as a closure for the dynamics of the Homogeneous Isotropic Boltzmann Equation (HIBE) with a realistic description for particle collisions, namely the hard-sphere model. The behaviour of QMOM far away and approaching the equilibrium is studied. Results are compared to other techniques such as the Grad's moment method (GM) and the off-Lattice Boltzmann Method (oLBM). Comparison with a more accurate and computationally expensive approach, based on the Discrete Velocity Method (DVM), is also carried out. Our results show that QMOM describes very well the evolution when it is far away from equilibrium, without the drawbacks of the GM and oLBM or the computational costs of DVM, but it is not able to accurately reproduce equilibrium and the dynamics close to it. Static and dynamic corrections to cure this behaviour are here proposed and tested.

  20. 0.8-5.2GHz Broad-Band SiGe-MMIC Quadrature Mixer for Software Defined Radio Receiver

    NASA Astrophysics Data System (ADS)

    Murakami, Keishi; Suematsu, Noriharu; Tsutsumi, Koji; Kanazawa, Gakushi; Sekine, Tomotsugu; Kubo, Hiroshi; Isota, Yoji

    For the next generation wireless terminals used in the software defined radio (SDR), multi-band / multi-mode transceivers and their MMIC are required which cover the wide RF frequency range from several hundreds MHz up to several GHz. In this paper, 0.8-5.2GHz broad-band SiGe-MMIC quadrature mixer (Q-MIX) for multi-band / multi-mode direct conversion receiver has been developed. By using a static type frequency divider as a 90 degrees local (LO) power divider, measured error vector magnitude (EVM) of less than 3.1% can be achieved in the cases of 0.8/2.1GHz W-CDMA and 5.2GHz wireless Local Area Network (LAN) (IEEE 802.11a) reception. This Q-MIX also shows broad-band characteristic for base-band signal and is applicable for 4G cellular. By using fabricated Q-MIX, a multi-band / multi-mode (1.9GHz (3rd generation cellular (W-CDMA)) / 5.2GHz (4th generation cellular (Multi-Carrier (MC)-CDMA))) receiver has been developed and it has firstly demonstrated the successful reception of motion picture via W-CDMA and MC-CDMA.

  1. Tensor Green's function evaluation in arbitrarily anisotropic, layered media using complex-plane Gauss-Laguerre quadrature.

    PubMed

    Sainath, Kamalesh; Teixeira, Fernando L

    2014-05-01

    We discuss the application of complex-plane Gauss-Laguerre quadrature (CGLQ) to efficiently evaluate two-dimensional Fourier integrals arising as the solution to electromagnetic fields radiated by elementary dipole antennas embedded within planar-layered media exhibiting arbitrary material parameters. More specifically, we apply CGLQ to the long-standing problem of rapidly and efficiently evaluating the semi-infinite length "tails" of the Fourier integral path while simultaneously and robustly guaranteeing absolute, exponential convergence of the field solution despite diversity in the doubly anisotropic layer parameters, source type (i.e., electric or equivalent magnetic dipole), source orientation, observed field type (magnetic or electric), (nonzero) frequency, and (nonzero) source-observer separation geometry. The proposed algorithm exhibits robustness despite unique challenges arising for the fast evaluation of such two-dimensional integrals. Herein we develop the mathematical treatment to rigorously evaluate the tail integrals using CGLQ, as well as discuss and address the specific issues posed to the CGLQ method when anisotropic, layered media are present. To empirically demonstrate the CGLQ algorithm's computational efficiency, versatility, and accuracy, we perform a convergence analysis along with two case studies related to modeling of electromagnetic resistivity tools employed in geophysical prospection of layered, anisotropic Earth media and validating the ability of isoimpedance substrates to enhance the radiation performance of planar antennas placed in close proximity to metallic ground planes.

  2. Bounds and Simulation Results of 32-ary and 64-ary Quadrature Amplitude Modulation for Broadband-ISDN via Satellite

    NASA Technical Reports Server (NTRS)

    Kifle, Muli; Vanderaar, Mark

    1994-01-01

    Union bounds and Monte Carlo simulation Bit-Error-Rate (BER) performance results are presented for various 32-ary and 64-ary Quadrature Amplitude Modulation (QAM) schemes. Filtered and unfiltered modulation formats are compared for the best packing arrangement in peak power limited systems. It is verified that circular constellations which populate as many symbols as possible at the peak magnitude offer the best performance. For example: a 32-ary QAM scheme based on concentric circles offers about 1.05 dB better peak power improvement at a BER of 10(exp -6) over the scheme optimized for average power using triangular symbol packing. This peak power improvement increases to 1.25 dB for comparable 64-ary QAM schemes. This work serves as a precursor to determine the feasibility of a combined modem/codec that can accommodate Broadband Integrated Services Digital Network (B-ISDN) at a rate of 155.52 Mbps through typical transponder bandwidths of 36 MHz and 54 MHz.

  3. A hybrid layerwise and differential quadrature method for in-plane free vibration of laminated thick circular arches

    NASA Astrophysics Data System (ADS)

    Malekzadeh, P.; Setoodeh, A. R.; Barmshouri, E.

    2008-08-01

    An accurate and efficient solution procedure based on the two-dimensional elasticity theory for free vibration of arbitrary laminated thick circular deep arches with some combinations of classical boundary conditions is introduced. In order to accurately represent the variation of strain across the thickness, the layerwise theory is used to approximate the displacement components in the radial direction. Employing Hamilton's principle, the discretized form of the equations of motion and the related boundary conditions in the radial direction are obtained. The resulting governing equations are then discretized using the differential quadrature method (DQM). After performing the convergence studies, new results for laminated arches with different set of boundary conditions are developed. Additionally, different values of the arch parameters such as opening angle, thickness-to-length and orthotropy ratios are considered. In all cases, comparisons with the results obtained using the finite element software 'ABAQUS' and also with those of the first- and higher-order shear deformation theories available in the literature are performed. Close agreements, especially with those of ABAQUS, are achieved.

  4. A Quadrature-Based Tunable Radio-Frequency Sensor for the Detection and Analysis of Aqueous Solutions.

    PubMed

    Cui, Yan; He, Yuxi; Wang, Pingshan

    2014-07-01

    A highly tunable and sensitive radio-frequency (RF) sensor is presented for the measurement of aqueous-solution dielectric properties. Two quadrature hybrids are utilized to achieve destructive interference that eliminates the probing signals at both measurement ports. As a result, weak signals of material-under-test (MUT) are elevated for high sensitivity detections at different frequencies. The sensor is demonstrated through measuring 2-propanol-water solution permittivity at 0.01 mole fraction concentration level from ~4 GHz to ~12 GHz. De-ionized water and methanol-water solution are used to calibrate the sensor for quantitative MUT analysis through our proposed model. Micro-meter coplanar waveguides (CPW) are fabricated as RF sensing electrodes. A polydimethylsiloxane (PDMS) microfluidic channel is employed to introduce 250 nL liquid, of which ~1 nL is effectively the MUT. The permittivity and the relaxation time of 2-propanol-water solution are obtained. Compared with our power divider based sensors, the differential reflection coefficients in this work provide additional information that complements the transmission coefficient methods.

  5. Optical channel de-aggregation of quadrature-phase-shift-keying and eight-phase-shift-keying data using mapping onto constellation axes.

    PubMed

    Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Almaiman, Ahmed; Cao, Yinwen; Chitgarha, Mohammad Reza; Paraschis, Loukas; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Touch, Joseph D; Willner, Alan E

    2015-11-01

    An eight-phase-shift-keying signal is experimentally de-aggregated onto two four-pulse amplitude modulation signals using nonlinear processes in optical elements. Quadrature-phase-shift-keying signals are similarly de-multiplexed into two binary phase shift keying signals by mapping the data points onto the constellation axes. De-multiplexing performance is evaluated as a function of the optical signal-to-noise ratio of the incoming signals. The effect of phase noise is also studied.

  6. Evaluating the potential for quantitative monitoring of in situ chemical oxidation of aqueous-phase TCE using in-phase and quadrature electrical conductivity

    NASA Astrophysics Data System (ADS)

    Hort, R. D.; Revil, A.; Munakata-Marr, J.; Mao, D.

    2015-07-01

    Electrical resistivity measurements can potentially be used to remotely monitor fate and transport of ionic oxidants such as permanganate (MnO4-) during in situ chemical oxidation (ISCO) of contaminants like trichloroethene (TCE). Time-lapse two-dimensional bulk conductivity and induced polarization surveys conducted during a sand tank ISCO simulation demonstrated that MnO4- plume movement could be monitored in a qualitative manner using bulk conductivity tomograms, although chargeability was below sensitivity limits. We also examined changes to in-phase and quadrature electrical conductivity resulting from ion injection, MnO2 and Cl- production, and pH change during TCE and humate oxidation by MnO4- in homogeneous aqueous solutions and saturated porous media samples. Data from the homogeneous samples demonstrated that inversion of the sand tank resistivity data using a common Tikhonov regularization approach was insufficient to recover an accurate conductivity distribution within the tank. While changes to in-phase conductivity could be successfully modeled, quadrature conductivity values could not be directly related to TCE oxidation product or MnO4- concentrations at frequencies consistent with field induced polarization surveys, limiting the utility of quadrature conductivity for monitoring ISCO.

  7. QUADRATURE OBSERVATIONS OF WAVE AND NON-WAVE COMPONENTS AND THEIR DECOUPLING IN AN EXTREME-ULTRAVIOLET WAVE EVENT

    SciTech Connect

    Dai, Y.; Ding, M. D.; Chen, P. F.; Zhang, J.

    2012-11-01

    We report quadrature observations of an extreme-ultraviolet (EUV) wave event on 2011 January 27 obtained by the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory, and the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Two components are revealed in the EUV wave event. A primary front is launched with an initial speed of {approx}440 km s{sup -1}. It appears that significant emission enhancement occurs in the hotter channel while deep emission reduction occurs in the cooler channel. When the primary front encounters a large coronal loop system and slows down, a secondary, much fainter, front emanates from the primary front with a relatively higher starting speed of {approx}550 km s{sup -1}. Afterward, the two fronts propagate independently with increasing separation. The primary front finally stops at a magnetic separatrix, while the secondary front travels farther until it fades out. In addition, upon the arrival of the secondary front, transverse oscillations of a prominence are triggered. We suggest that the two components are of different natures. The primary front belongs to a non-wave coronal mass ejection (CME) component, which can be reasonably explained with the field-line stretching model. The multi-temperature behavior may be caused by considerable heating due to nonlinear adiabatic compression on the CME frontal loop. As for the secondary front, it is most likely a linear fast-mode magnetohydrodynamic wave that propagates through a medium of the typical coronal temperature. X-ray and radio data provide us with complementary evidence in support of the above scenario.

  8. Demonstration of high-speed quadrature phase shift keying vector signal generation employing a single Mach-Zehnder modulator with phase precoding technology

    NASA Astrophysics Data System (ADS)

    Wang, Yanyi; Li, Xinying; Yu, Jianjun

    2016-01-01

    We numerically and experimentally investigate high-speed quadrature phase shift keying (QPSK) vector signal generation based on a single Mach-Zehnder intensity modulator employing a precoding technique. We experimentally demonstrate 16-Gbaud QPSK vector signal generation at 16-GHz carrier adopting optical carrier suppression with precoding technique, and it is the highest baud rate generated by this technology. The 16-Gbaud QPSK modulated vector signal is delivered over a 20-km large effective area fiber or 2-km single-mode fiber with a bit-error-rate less than the hard-decision forward-error-correction threshold of 3.8×10-3.

  9. Eight-state trellis-coded optical modulation with signal constellations of four-dimensional M-ary quadrature-amplitude modulation.

    PubMed

    Ishimura, Shota; Kikuchi, Kazuro

    2015-03-01

    We apply the eight-state trellis-coded modulation (TCM) using signal constellations of four-dimensional M-ary quadrature-amplitude modulation (4D-MQAM) to optical communication systems for the first time to our knowledge. In the TCM scheme, the free distance of the trellis diagram is equal to the minimum distance between constellation points in partitioned subsets, which enlarges the coding gain effectively. In fact, its asymptotic power efficiency is 3-dB larger than that of the set-partitioned 4D-MQAM (SP-4D-MQAM) format, while their spectral efficiencies are the same. Such theoretical predictions are confirmed through computer simulations on eight-state TCM with constellations of 4D-4QAM (i.e., 4D quadrature phase-shift keying: 4D-QPSK) and 4D-16QAM. In particular, eight-state TCM with 4D-QPSK constellations is practically important because of its simple encoder structure, relatively low computational cost, and high coding gain against dual-polarization QPSK (DP-QPSK) and SP-4D-QPSK. Through measurements of its bit-error rate (BER) performance, we confirm that the coding gain against DP-QPSK is about 3 dB at BER=10(-3).

  10. 1D Current Source Density (CSD) Estimation in Inverse Theory: A Unified Framework for Higher-Order Spectral Regularization of Quadrature and Expansion-Type CSD Methods.

    PubMed

    Kropf, Pascal; Shmuel, Amir

    2016-07-01

    Estimation of current source density (CSD) from the low-frequency part of extracellular electric potential recordings is an unstable linear inverse problem. To make the estimation possible in an experimental setting where recordings are contaminated with noise, it is necessary to stabilize the inversion. Here we present a unified framework for zero- and higher-order singular-value-decomposition (SVD)-based spectral regularization of 1D (linear) CSD estimation from local field potentials. The framework is based on two general approaches commonly employed for solving inverse problems: quadrature and basis function expansion. We first show that both inverse CSD (iCSD) and kernel CSD (kCSD) fall into the category of basis function expansion methods. We then use these general categories to introduce two new estimation methods, quadrature CSD (qCSD), based on discretizing the CSD integral equation with a chosen quadrature rule, and representer CSD (rCSD), an even-determined basis function expansion method that uses the problem's data kernels (representers) as basis functions. To determine the best candidate methods to use in the analysis of experimental data, we compared the different methods on simulations under three regularization schemes (Tikhonov, tSVD, and dSVD), three regularization parameter selection methods (NCP, L-curve, and GCV), and seven different a priori spatial smoothness constraints on the CSD distribution. This resulted in a comparison of 531 estimation schemes. We evaluated the estimation schemes according to their source reconstruction accuracy by testing them using different simulated noise levels, lateral source diameters, and CSD depth profiles. We found that ranking schemes according to the average error over all tested conditions results in a reproducible ranking, where the top schemes are found to perform well in the majority of tested conditions. However, there is no single best estimation scheme that outperforms all others under all tested

  11. 1D Current Source Density (CSD) Estimation in Inverse Theory: A Unified Framework for Higher-Order Spectral Regularization of Quadrature and Expansion-Type CSD Methods.

    PubMed

    Kropf, Pascal; Shmuel, Amir

    2016-07-01

    Estimation of current source density (CSD) from the low-frequency part of extracellular electric potential recordings is an unstable linear inverse problem. To make the estimation possible in an experimental setting where recordings are contaminated with noise, it is necessary to stabilize the inversion. Here we present a unified framework for zero- and higher-order singular-value-decomposition (SVD)-based spectral regularization of 1D (linear) CSD estimation from local field potentials. The framework is based on two general approaches commonly employed for solving inverse problems: quadrature and basis function expansion. We first show that both inverse CSD (iCSD) and kernel CSD (kCSD) fall into the category of basis function expansion methods. We then use these general categories to introduce two new estimation methods, quadrature CSD (qCSD), based on discretizing the CSD integral equation with a chosen quadrature rule, and representer CSD (rCSD), an even-determined basis function expansion method that uses the problem's data kernels (representers) as basis functions. To determine the best candidate methods to use in the analysis of experimental data, we compared the different methods on simulations under three regularization schemes (Tikhonov, tSVD, and dSVD), three regularization parameter selection methods (NCP, L-curve, and GCV), and seven different a priori spatial smoothness constraints on the CSD distribution. This resulted in a comparison of 531 estimation schemes. We evaluated the estimation schemes according to their source reconstruction accuracy by testing them using different simulated noise levels, lateral source diameters, and CSD depth profiles. We found that ranking schemes according to the average error over all tested conditions results in a reproducible ranking, where the top schemes are found to perform well in the majority of tested conditions. However, there is no single best estimation scheme that outperforms all others under all tested

  12. Computing a numerical solution of two dimensional non-linear Schrödinger equation on complexly shaped domains by RBF based differential quadrature method

    NASA Astrophysics Data System (ADS)

    Golbabai, Ahmad; Nikpour, Ahmad

    2016-10-01

    In this paper, two-dimensional Schrödinger equations are solved by differential quadrature method. Key point in this method is the determination of the weight coefficients for approximation of spatial derivatives. Multiquadric (MQ) radial basis function is applied as test functions to compute these weight coefficients. Unlike traditional DQ methods, which were originally defined on meshes of node points, the RBFDQ method requires no mesh-connectivity information and allows straightforward implementation in an unstructured nodes. Moreover, the calculation of coefficients using MQ function includes a shape parameter c. A new variable shape parameter is introduced and its effect on the accuracy and stability of the method is studied. We perform an analysis for the dispersion error and different internal parameters of the algorithm are studied in order to examine the behavior of this error. Numerical examples show that MQDQ method can efficiently approximate problems in complexly shaped domains.

  13. Hybrid polarization-division-multiplexed quadrature phase-shift keying and multi-pulse pulse position modulation for free space optical communication

    NASA Astrophysics Data System (ADS)

    Shi, Wenxiao; Wu, Pengxia; Liu, Wei

    2015-01-01

    A new hybrid modulation scheme (PDM-QPSK-MPPM) for free space optical (FSO) communication is proposed in this paper, which is based on the combination of polarization-division-multiplexed quadrature phase-shift keying (PDM-QPSK) and multi-pulse pulse position modulation (MPPM). We describe the transmitter and receiver block diagram and the decoding scheme of proposed scheme, and derive the formulary expressions for symbol-error rate (SER) and upper bound of bit-error rate (BER) in Gamma-Gamma turbulence channel. Performance evaluations and comparisons are implemented through detailed analysis. The numerical results indicate that, under turbulence channel with average power constraint, the proposed hybrid PDM-QPSK-MPPM always offer better BER performance and SER performance than ordinary BPSK and MPPM. In addition, the proposed scheme offers higher bandwidth-utilization efficiency than conventional modulation formats.

  14. Miniaturized silicon photonic integrated swept source OCT receiver with dual polarization, dual balanced, in-phase and quadrature detection (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Zhao; Lee, Hsiang-Chieh; Chen, Long; Vermeulen, Diedrik; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2016-03-01

    Miniaturization and cost reduction of OCT systems are important for enabling many new clinical applications as well as accelerating the development of existing applications. Silicon photonics is an important low-cost, high-volume, multi-functional platform for integrated optics because it can benefit from existing semiconductor fabrication techniques to integrate many advanced optical functions onto a single microchip. We present a miniaturized silicon photonic integrated swept source OCT receiver, measuring 3×4mm2, with advanced functionalities including dual polarization, dual balanced, in-phase and quadrature detection, essentially enabling the detection of the full vector field (amplitude, phase, and polarization) of the optical signal. With this integrated receiver, we demonstrate full-range OCT for complex conjugate artifact suppression, polarization diversity detection for removing polarization fading artifact, and polarization sensitive OCT for tissue birefringence imaging. The silicon photonic integrated receiver is a key advance towards developing a miniaturized, multi-functional swept source OCT system.

  15. Lagrange interpolation and modified cubic B-spline differential quadrature methods for solving hyperbolic partial differential equations with Dirichlet and Neumann boundary conditions

    NASA Astrophysics Data System (ADS)

    Jiwari, Ram

    2015-08-01

    In this article, the author proposed two differential quadrature methods to find the approximate solution of one and two dimensional hyperbolic partial differential equations with Dirichlet and Neumann's boundary conditions. The methods are based on Lagrange interpolation and modified cubic B-splines respectively. The proposed methods reduced the hyperbolic problem into a system of second order ordinary differential equations in time variable. Then, the obtained system is changed into a system of first order ordinary differential equations and finally, SSP-RK3 scheme is used to solve the obtained system. The well known hyperbolic equations such as telegraph, Klein-Gordon, sine-Gordon, Dissipative non-linear wave, and Vander Pol type non-linear wave equations are solved to check the accuracy and efficiency of the proposed methods. The numerical results are shown in L∞ , RMS andL2 errors form.

  16. Silicon photonic integrated circuit swept-source optical coherence tomography receiver with dual polarization, dual balanced, in-phase and quadrature detection

    PubMed Central

    Wang, Zhao; Lee, Hsiang-Chieh; Vermeulen, Diedrik; Chen, Long; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2015-01-01

    Optical coherence tomography (OCT) is a widely used three-dimensional (3D) optical imaging method with many biomedical and non-medical applications. Miniaturization, cost reduction, and increased functionality of OCT systems will be critical for future emerging clinical applications. We present a silicon photonic integrated circuit swept-source OCT (SS-OCT) coherent receiver with dual polarization, dual balanced, in-phase and quadrature (IQ) detection. We demonstrate multiple functional capabilities of IQ polarization resolved detection including: complex-conjugate suppressed full-range OCT, polarization diversity detection, and polarization-sensitive OCT. To our knowledge, this is the first demonstration of a silicon photonic integrated receiver for OCT. The integrated coherent receiver provides a miniaturized, low-cost solution for SS-OCT, and is also a key step towards a fully integrated high speed SS-OCT system with good performance and multi-functional capabilities. With further performance improvement and cost reduction, photonic integrated technology promises to greatly increase penetration of OCT systems in existing applications and enable new applications. PMID:26203382

  17. Gauss-Jacobi quadratures for weakly, strongly, hyper- and nearly-singular integrals in boundary integral equation methods for domains with sharp edges and corners

    NASA Astrophysics Data System (ADS)

    Tsalamengas, John L.

    2016-11-01

    We present Gauss-Jacobi quadrature rules in terms of hypergeometric functions for the discretization of weakly singular, strongly singular, hypersingular, and nearly singular integrals that arise in integral equation formulations of potential problems for domains with sharp edges and corners. The rules are tailored to weight functions with algebraic endpoint singularities of a fairly general form, thus allowing one to easily incorporate a wide class of domains into the analysis. Numerical examples illustrate the accuracy and stability of the proposed algorithms; it is shown that the same level of high accuracy can be achieved for any choice of the external variable. The usefulness of the method is exemplified by application to the solution of a singular integral equation that arises in time-harmonic electromagnetic scattering by either closed or open perfectly conducting cylindrical objects with edges and corners, such as polygon cylinders and bent strips. Some practical aspects concerning the role of nearby singularities in achieving a highly accurate solution of singular integral equations are, also, discussed.

  18. Silicon photonic integrated circuit swept-source optical coherence tomography receiver with dual polarization, dual balanced, in-phase and quadrature detection.

    PubMed

    Wang, Zhao; Lee, Hsiang-Chieh; Vermeulen, Diedrik; Chen, Long; Nielsen, Torben; Park, Seo Yeon; Ghaemi, Allan; Swanson, Eric; Doerr, Chris; Fujimoto, James

    2015-07-01

    Optical coherence tomography (OCT) is a widely used three-dimensional (3D) optical imaging method with many biomedical and non-medical applications. Miniaturization, cost reduction, and increased functionality of OCT systems will be critical for future emerging clinical applications. We present a silicon photonic integrated circuit swept-source OCT (SS-OCT) coherent receiver with dual polarization, dual balanced, in-phase and quadrature (IQ) detection. We demonstrate multiple functional capabilities of IQ polarization resolved detection including: complex-conjugate suppressed full-range OCT, polarization diversity detection, and polarization-sensitive OCT. To our knowledge, this is the first demonstration of a silicon photonic integrated receiver for OCT. The integrated coherent receiver provides a miniaturized, low-cost solution for SS-OCT, and is also a key step towards a fully integrated high speed SS-OCT system with good performance and multi-functional capabilities. With further performance improvement and cost reduction, photonic integrated technology promises to greatly increase penetration of OCT systems in existing applications and enable new applications.

  19. Gauss-Legendre quadrature method used to evaluate the spatio-temporal intensity of ultrashort pulses in the focal region of lenses.

    PubMed

    García-Martínez, L; Rosete-Aguilar, M; Garduño-Mejia, J

    2012-01-20

    We analyze the spatio-temporal intensity of sub-20 femtosecond pulses with a carrier wavelength of 810 nm along the optical axis of low numerical aperture achromatic and apochromatic doublets designed in the IR region by using the scalar diffraction theory. The diffraction integral is solved by expanding the wave number around the carrier frequency of the pulse in a Taylor series up to third order, and then the integral over the frequencies is solved by using the Gauss-Legendre quadrature method. The numerical errors in this method are negligible by taking 96 nodes and the computational time is reduced by 95% compared to the integration method by rectangles. We will show that the third-order group velocity dispersion (GVD) is not negligible for 10 fs pulses at 810 nm propagating through the low numerical aperture doublets, and its effect is more important than the propagation time difference (PTD). This last effect, however, is also significant. For sub-20 femtosecond pulses, these two effects make the use of a pulse shaper necessary to correct for second and higher-order GVD terms and also the use of apochromatic optics to correct the PTD effect. The design of an apochromatic doublet is presented in this paper and the spatio-temporal intensity of the pulse at the focal region of this doublet is compared to that given by the achromatic doublet.

  20. Representation of solutions to the problem of the motion of a heavy rigid body in the Kovalevskaya case in terms of Weierstrass \\zeta- and \\wp-functions and nonintegrability of the Hess case by quadratures

    NASA Astrophysics Data System (ADS)

    Belyaev, A. V.

    2016-07-01

    A method for the representation of Delaunay's solutions and some other particular solutions to the problem of the motion of a heavy rigid body in the Kovalevskaya case in terms of the Weierstrass \\zeta- and \\wp-functions is put forward. The Hess case in the problem of the motion of a heavy rigid body is shown to be nonintegrable by quadratures. Bibliography: 24 titles.

  1. 2  ×  2 multiple-input multiple-output optical-wireless integration system based on optical independent-sideband modulation enabled by an in-phase/quadrature modulator.

    PubMed

    Li, Xinying; Yu, Jianjun

    2016-07-01

    We propose a novel and simple 2×2 multiple-input multiple-output (MIMO) optical-wireless integration system, in which optical independent-sideband modulation enabled by an in-phase/quadrature (I/Q) modulator, instead of optical polarization multiplexing, is used to assist the simultaneous generation of two wireless millimeter-wave (mm-wave) signals. Software-based digital signal processing is used to generate the driving signal for the I/Q modulator, the output of which is two independent single-sideband optical vector signals located at two sides of a large central optical carrier. Based on our proposed 2×2 MIMO optical-wireless integration system, we experimentally demonstrate the simultaneous generation and 2×2 MIMO wireless delivery of two independent 40-GHz quadrature-phase-shift-keying (QPSK) wireless mm-wave signals. Each 40-GHz QPSK wireless mm-wave signal can carry up to 4-Gbaud transmitter data with a bit-error ratio less than the hard-decision forward-error-correction threshold of 3.8×10-3.

  2. A Low-Cost 16 Quadrature Amplitude Modulation Direct-Detection-Orthogonal Frequency-Division Multiplexing Radio-over-Fiber System Using Low-Cost Direct-Modulation Laser to Generate Optical mm-Wave

    NASA Astrophysics Data System (ADS)

    Nguyen, HoangViet

    2015-07-01

    This article demonstrates a novel scheme to generate 16 quadrature amplitude modulation orthogonal frequency-division multiplexing signals for radio-over-fiber systems using a low-cost direct-modulation laser to generate an optical millimeter-wave. Mathematical analysis of that system is also investigated. The fiber Bragg grating is employed because the repetitive frequency of the radio frequency source and the bandwidth of the optical modulator are largely reduced, and the architecture of the radio-over-fiber system is simpler. Because no expensive broadband external modulator is used, the overall system is considered a low-cost solution. The simple structure and low cost of the radio-over-fiber system is attractive for the future cost-effective systems.

  3. Comparisons between the 35 mm Quadrature Surface Resonator at 300 K and the 40 mm High-Temperature Superconducting Surface Resonator at 77 K in a 3T MRI Imager

    PubMed Central

    Song, Manli; Chen, Jyh-Horng; Chen, Ji; Lin, In-Tsang

    2015-01-01

    This study attempts to compare the signal-to-noise ratio (SNR) of the 40 mm High-Temperature Superconducting (HTS) surface resonator at 77 K and the 35 mm commercial quadrature (QD) surface resonator at 300 K in a 3 Tesla (T) MRI imager. To aquire images for the comparison, we implemented a phantom experiment using the 40 mm diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) HTS surface resonator, the 35 mm commercial QD surface resonator and the 40 mm professionally-made copper surface resonator. The HTS surface resonator at 77 K provided a 1.43-fold SNR gain over the QD surface resonator at 300 K and provided a 3.84-fold SNR gain over the professionally-made copper surface resonator at 300 K on phantom images. The results agree with the predictions, and the difference between the predicted SNR gains and measured SNR gains is 1%. Although the geometry of the HTS surface resonator is different from the QD surface resonator, its SNR is still higher. The results demonstrate that a higher image quality can be obtained with the HTS surface resonator at 77 K. With the HTS surface resonator, the SNR can be improved, suggesting that the HTS surface resonator is a potentially helpful diagnostic tool for MRI imaging in various applications. PMID:25812124

  4. Numerical quadrature for slab geometry transport algorithms

    SciTech Connect

    Hennart, J.P.; Valle, E. del

    1995-12-31

    In recent papers, a generalized nodal finite element formalism has been presented for virtually all known linear finite difference approximations to the discrete ordinates equations in slab geometry. For a particular angular directions {mu}, the neutron flux {Phi} is approximated by a piecewise function Oh, which over each space interval can be polynomial or quasipolynomial. Here we shall restrict ourselves to the polynomial case. Over each space interval, {Phi} is a polynomial of degree k, interpolating parameters given by in the continuous and discontinuous cases, respectively. The angular flux at the left and right ends and the k`th Legendre moment of {Phi} over the cell considered are represented as.

  5. An orthogonal oriented quadrature hexagonal image pyramid

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Ahumada, Albert J., Jr.

    1987-01-01

    An image pyramid has been developed with basis functions that are orthogonal, self-similar, and localized in space, spatial frequency, orientation, and phase. The pyramid operates on a hexagonal sample lattice. The set of seven basis functions consist of three even high-pass kernels, three odd high-pass kernels, and one low-pass kernel. The three even kernels are identified when rotated by 60 or 120 deg, and likewise for the odd. The seven basis functions occupy a point and a hexagon of six nearest neighbors on a hexagonal sample lattice. At the lowest level of the pyramid, the input lattice is the image sample lattice. At each higher level, the input lattice is provided by the low-pass coefficients computed at the previous level. At each level, the output is subsampled in such a way as to yield a new hexagonal lattice with a spacing sq rt 7 larger than the previous level, so that the number of coefficients is reduced by a factor of 7 at each level. The relationship between this image code and the processing architecture of the primate visual cortex is discussed.

  6. Hollow vortices, capillary water waves and double quadrature domains

    NASA Astrophysics Data System (ADS)

    Crowdy, Darren G.; Roenby, Johan

    2014-06-01

    Two new classes of analytical solutions for hollow vortex equilibria are presented. One class involves a central hollow vortex, comprising a constant pressure region having non-zero circulation, surrounded by an n-polygonal array of point vortices with n\\geqslant 2. The solutions generalize the non-rotating polygonal point vortex configurations of Morikawa and Swenson (1971 Phys. Fluids 14 1058-73) to the case where the point vortex at the centre of the polygon is replaced by a hollow vortex. The results of Morikawa and Swenson would suggest that all equilibria for n\

  7. Fidelity between Gaussian mixed states with quantum state quadrature variances

    NASA Astrophysics Data System (ADS)

    Hai-Long, Zhang; Chun, Zhou; Jian-Hong, Shi; Wan-Su, Bao

    2016-04-01

    In this paper, from the original definition of fidelity in a pure state, we first give a well-defined expansion fidelity between two Gaussian mixed states. It is related to the variances of output and input states in quantum information processing. It is convenient to quantify the quantum teleportation (quantum clone) experiment since the variances of the input (output) state are measurable. Furthermore, we also give a conclusion that the fidelity of a pure input state is smaller than the fidelity of a mixed input state in the same quantum information processing. Project supported by the National Basic Research Program of China (Grant No. 2013CB338002) and the Foundation of Science and Technology on Information Assurance Laboratory (Grant No. KJ-14-001).

  8. Fidelity between Gaussian mixed states with quantum state quadrature variances

    NASA Astrophysics Data System (ADS)

    Hai-Long, Zhang; Chun, Zhou; Jian-Hong, Shi; Wan-Su, Bao

    2016-04-01

    In this paper, from the original definition of fidelity in a pure state, we first give a well-defined expansion fidelity between two Gaussian mixed states. It is related to the variances of output and input states in quantum information processing. It is convenient to quantify the quantum teleportation (quantum clone) experiment since the variances of the input (output) state are measurable. Furthermore, we also give a conclusion that the fidelity of a pure input state is smaller than the fidelity of a mixed input state in the same quantum information processing. Project supported by the National Basic Research Program of China (Grant No. 2013CB338002) and the Foundation of Science and Technology on Information Assurance Laboratory (Grant No. KJ-14-001).

  9. Radio frequency path characterization for wide band quadrature amplitude modulation

    SciTech Connect

    Bracht, R.

    1998-12-31

    Remote, high speed, high explosive wave front monitoring requires very high bandwidth telemetry to allow transmission of diagnostic data before the explosion destroys the sensor system itself. The main motivation for this study is that no known existing implementation of this sort has been applied to realistic weapons environments. These facts have prompted the research and gathering of data that can be used to extrapolate towards finding the best modulation method for this application. In addition to research of similar existing analysis and testing operations, data was recently captured from a Joint Test Assembly (JTA) Air Launched Cruise Missile (ALCM) flight.

  10. Quadrature Moments Method for the Simulation of Turbulent Reactive Flows

    NASA Technical Reports Server (NTRS)

    Raman, Venkatramanan; Pitsch, Heinz; Fox, Rodney O.

    2003-01-01

    A sub-filter model for reactive flows, namely the DQMOM model, was formulated for Large Eddy Simulation (LES) using the filtered mass density function. Transport equations required to determine the location and size of the delta-peaks were then formulated for a 2-peak decomposition of the FDF. The DQMOM scheme was implemented in an existing structured-grid LES solver. Simulations of scalar shear layer using an experimental configuration showed that the first and second moments of both reactive and inert scalars are in good agreement with a conventional Lagrangian scheme that evolves the same FDF. Comparisons with LES simulations performed using laminar chemistry assumption for the reactive scalar show that the new method provides vast improvements at minimal computational cost. Currently, the DQMOM model is being implemented for use with the progress variable/mixture fraction model of Pierce. Comparisons with experimental results and LES simulations using a single-environment for the progress-variable are planned. Future studies will aim at understanding the effect of increase in environments on predictions.

  11. Atomic-position resolution by quadrature-field measurement

    NASA Astrophysics Data System (ADS)

    Storey, Pippa; Collett, Matthew; Walls, Daniel

    1993-01-01

    An atom passing through a standing light field imparts a position-dependent phase shift to the field. By making a phase-sensitive measurement of the field, it is possible to resolve the atom's position to much less than the wavelength of the light. The field measurement results in the creation of virtual slits, and diffraction and interference phenomena may be observed. The phase measurements give welcher Weg information and enable ``quantum-eraser'' experiments to be realized.

  12. A novel sample based quadrature phase shift keying demodulator.

    PubMed

    Mohamed Moubark, Asraf; Ali, Sawal Hamid Md

    2014-01-01

    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10(-6), whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.

  13. A Novel Sample Based Quadrature Phase Shift Keying Demodulator

    PubMed Central

    Ali, Sawal Hamid Md

    2014-01-01

    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10−6, whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator. PMID:25197687

  14. Pulsed laser interferometry with sub-picometer resolution using quadrature detection.

    PubMed

    Shao, Lei; Gorman, Jason J

    2016-07-25

    Femtosecond pulsed laser interferometry has important applications in measuring picometer-level displacements on sub-nanosecond time scales. In this paper, we experimentally examine its achievable displacement resolution, as well as the relationship between the laser's optical spectrum and the interferometer's effective wavelength. The resulting broadband displacement noise and noise floor of the pulsed laser Michelson interferometer are equivalent to that achieved with a stabilized continuous wave HeNe laser, where values of 1.01 nm RMS and 27.75 fm/√Hz have been demonstrated. It is also shown that a single effective wavelength can accurately describe the fringes of the pulsed laser interferometer but the effective wavelength value can only be determined from the optical spectrum under certain conditions. These results will be used for time-resolved displacement metrology with picosecond temporal resolution in the future. PMID:27464192

  15. A computational approach for hypersonic nonequilibrium radiation utilizing space partition algorithm and Gauss quadrature

    SciTech Connect

    Shang, J.S.; Andrienko, D.A.; Huang, P.G.; Surzhikov, S.T.

    2014-06-01

    An efficient computational capability for nonequilibrium radiation simulation via the ray tracing technique has been accomplished. The radiative rate equation is iteratively coupled with the aerodynamic conservation laws including nonequilibrium chemical and chemical–physical kinetic models. The spectral properties along tracing rays are determined by a space partition algorithm of the nearest neighbor search process, and the numerical accuracy is further enhanced by a local resolution refinement using the Gauss–Lobatto polynomial. The interdisciplinary governing equations are solved by an implicit delta formulation through the diminishing residual approach. The axisymmetric radiating flow fields over the reentry RAM-CII probe have been simulated and verified with flight data and previous solutions by traditional methods. A computational efficiency gain nearly forty times is realized over that of the existing simulation procedures.

  16. The 2011 February 15 Coronal Mass Ejection: Reconciling SOHO and STEREO Observations in Quadrature

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Yashiro, S.; Makela, P.; Kaiser, M. L.

    2011-05-01

    The Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO observed a fast halo coronal mass ejection on 2011 February 15. The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth by 87 deg and STEREO-B 94 deg behind Earth), enabling CME measurement using the three spacecraft. The sky-plane speed measured by SOHO/LASCO is closely related to the expansion speed of the CME, while the radial speed was measured by STEREO-A and STEREO-B. In addition, STEREO-A and STEREO-B images measured the width of the CME, which is unknown from Earth view. From the SOHO and STEREO measurements, we confirm the relationship between the expansion speed (Vexp) and radial speed (Vrad) derived previously from geometrical considerations (Gopalswamy et al. 2009): = Vrad = ½ (1 + cot w) Vexp, where w is the half width of the CME. We can also measure the Earthward speed of the CME directly from the STEREO measurements. The travel time to Earth predicted from the Earthward speed using the Empirical Shock Arrival model is 12 hours shorter than the actual travel time obtained from in situ measurements at L1. The primary reason for this discrepancy seems to be the interaction with the two preceding CMEs that slowed down the CME in question. The CME interaction is also confirmed from the radio enhancement observed by Wind/WAVES and STEREO WAVES experiments.

  17. Spherical-earth Gravity and Magnetic Anomaly Modeling by Gauss-legendre Quadrature Integration

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (Principal Investigator)

    1981-01-01

    The anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical Earth for an arbitrary body represented by an equivalent point source distribution of gravity poles or magnetic dipoles were calculated. The distribution of equivalent point sources was determined directly from the coordinate limits of the source volume. Variable integration limits for an arbitrarily shaped body are derived from interpolation of points which approximate the body's surface envelope. The versatility of the method is enhanced by the ability to treat physical property variations within the source volume and to consider variable magnetic fields over the source and observation surface. A number of examples verify and illustrate the capabilities of the technique, including preliminary modeling of potential field signatures for Mississippi embayment crustal structure at satellite elevations.

  18. Atom-assisted quadrature squeezing of a mechanical oscillator inside a dispersive cavity

    NASA Astrophysics Data System (ADS)

    Biswas, Asoka; Chauhan, Anil Kumar

    2016-05-01

    Measurement of position of a mesoscopic harmonic oscillator below standard quantum limit in cavity optomechanics has seen a growing interest in recent times. If the oscillator is suspended inside the cavity (with both the mirrors fixed) at a position where the cavity frequency becomes extremum (a membrane-in-the-middle setup), large squeezing can be achieved by conditional measurement of thermal photons; however the cavity decay degrades such squeezing. Here we propose an atom-cavity-oscillator hybrid scheme, in which the effect of cavity decay is eliminated via dispersive coupling of the cavity mode. The atom in Λ configuration is considered to be trapped on either side of the membrane inside the cavity. We show that a considerable amount of squeezing (far beyond the 3 dB limit) can be achieved that is not affected by spontaneous emission of the atom. The squeezing depends upon the initial preparation of the atomic states. Further, the external classical fields, that drive the atomic transition and the cavity mode, control the degree of squeezing and can also lead to a strong effective atom-oscillator coupling. Effect of thermal phonon bath on squeezing is studied in terms of the squeezing spectrum. The results are supported by the detailed analytical calculations.

  19. Recent developments in Bayesian inference of tokamak plasma equilibria and high-dimensional stochastic quadratures

    NASA Astrophysics Data System (ADS)

    von Nessi, G. T.; Hole, M. J.; The MAST Team

    2014-11-01

    We present recent results and technical breakthroughs for the Bayesian inference of tokamak equilibria using force-balance as a prior constraint. Issues surrounding model parameter representation and posterior analysis are discussed and addressed. These points motivate the recent advancements embodied in the Bayesian Equilibrium Analysis and Simulation Tool (BEAST) software being presently utilized to study equilibria on the Mega-Ampere Spherical Tokamak (MAST) experiment in the UK (von Nessi et al 2012 J. Phys. A 46 185501). State-of-the-art results of using BEAST to study MAST equilibria are reviewed, with recent code advancements being systematically presented though out the manuscript.

  20. Quadrature amplitude modulation (QAM) using binary-driven coupling-modulated rings

    NASA Astrophysics Data System (ADS)

    Karimelahi, Samira; Sheikholeslami, Ali

    2016-05-01

    We propose and fully analyze a compact structure for DAC-free pure optical QAM modulation. The proposed structure is the first ring resonator-based DAC-free QAM modulator reported in the literature, to the best of our knowledge. The device consists of two segmented add-drop Mach Zehnder interferometer-assisted ring modulators (MZIARM) in an IQ configuration. The proposed architecture is investigated based on the parameters from SOI technology where various key design considerations are discussed. We have included the loss in the MZI arms in our analysis of phase and amplitude modulation using MZIARM for the first time and show that the imbalanced loss results in a phase error. The output level linearity is also studied for both QAM-16 and QAM-64 not only based on optimizing RF segment lengths but also by optimizing the number of segments. In QAM-16, linearity among levels is achievable with two segments while in QAM-64 an additional segment may be required.

  1. Advances in Disentangling Age, Cohort, and Time Effects: No Quadrature of the Circle, but a Help

    ERIC Educational Resources Information Center

    Masche, J. Gowert; van Dulmen, Manfred H. M.

    2004-01-01

    Based on Schaie's (1965) general developmental model, various data-driven and theory-based approaches to the exploration and disentangling of age, cohort, and time effects on human behavior have emerged. This paper presents and discusses an advancement of data-driven interpretations that stresses parsimony when interpreting the results of…

  2. Coarse-grained computation for particle coagulation and sintering processes by linking Quadrature Method of Moments with Monte-Carlo

    SciTech Connect

    Zou Yu; Kavousanakis, Michail E.; Kevrekidis, Ioannis G.; Fox, Rodney O.

    2010-07-20

    The study of particle coagulation and sintering processes is important in a variety of research studies ranging from cell fusion and dust motion to aerosol formation applications. These processes are traditionally simulated using either Monte-Carlo methods or integro-differential equations for particle number density functions. In this paper, we present a computational technique for cases where we believe that accurate closed evolution equations for a finite number of moments of the density function exist in principle, but are not explicitly available. The so-called equation-free computational framework is then employed to numerically obtain the solution of these unavailable closed moment equations by exploiting (through intelligent design of computational experiments) the corresponding fine-scale (here, Monte-Carlo) simulation. We illustrate the use of this method by accelerating the computation of evolving moments of uni- and bivariate particle coagulation and sintering through short simulation bursts of a constant-number Monte-Carlo scheme.

  3. High-order time-stepping for nonlinear PDEs through rapid estimation of block Gaussian quadrature nodes

    NASA Astrophysics Data System (ADS)

    Lambers, James V.

    2016-06-01

    The stiffness of systems of ODEs that arise from spatial discretization of PDEs causes difficulties for both explicit and implicit time-stepping methods. Krylov Subspace Spectral (KSS) methods present a balance between the efficiency of explicit methods and the stability of implicit methods by computing each Fourier coefficient from an individualized approximation of the solution operator of the PDE. While KSS methods are explicit methods that exhibit a high order of accuracy and stability similar to that of implicit methods, their efficiency needs to be improved. Here, a detailed asymptotic study is performed in order to rapidly estimate all nodes, thus drastically reducing computational expense without sacrificing accuracy. Extension to PDEs on a disk, through expansions built on Legendre polynomials, is also discussed. Exponential propagation iterative (EPI) methods provide an efficient approach to the solution of large stiff nonlinear systems of ODE, compared to standard integrators. However, the bulk of the computational effort in these methods is due to products of matrix functions and vectors, which can become very costly at high resolution due to an increase in the number of Krylov projection steps needed to maintain accuracy. In this talk, it is proposed to modify EPI methods by using KSS methods, instead of standard Krylov projection methods, to compute products of matrix functions and vectors. Numerical experiments demonstrate that this modification causes the number of Krylov projection steps to become bounded independently of the grid size, thus dramatically improving efficiency and scalability. It is also demonstrated that the convergence of Krylov projection can be significantly accelerated, without noticeable loss of accuracy, through filtering techniques, thus improving performance and scalability even further.

  4. Liquid crystal free energy relaxation by a theoretically informed Monte Carlo method using a finite element quadrature approach.

    PubMed

    Armas-Pérez, Julio C; Hernández-Ortiz, Juan P; de Pablo, Juan J

    2015-12-28

    A theoretically informed Monte Carlo method is proposed for Monte Carlo simulation of liquid crystals on the basis of theoretical representations in terms of coarse-grained free energy functionals. The free energy functional is described in the framework of the Landau-de Gennes formalism. A piecewise finite element discretization is used to approximate the alignment field, thereby providing an excellent geometrical representation of curved interfaces and accurate integration of the free energy. The method is suitable for situations where the free energy functional includes highly non-linear terms, including chirality or high-order deformation modes. The validity of the method is established by comparing the results of Monte Carlo simulations to traditional Ginzburg-Landau minimizations of the free energy using a finite difference scheme, and its usefulness is demonstrated in the context of simulations of chiral liquid crystal droplets with and without nanoparticle inclusions.

  5. Long-Distance Continuous-Variable Quantum Key Distribution with Scalar Reconciliation and Gaussian Adaptive Multicarrier Quadrature Division

    NASA Astrophysics Data System (ADS)

    Gyongyosi, Laszlo; Imre, Sandor

    2014-03-01

    The two-way Continuous-Variable Quantum Key Distribution (CVQKD) systems allow higher key rates and improved transmission distances over standard telecommunication networks in comparison to the one-way CVQKD protocols. To exploit the real potential of two-way CVQKD systems a robust reconciliation technique is needed. It is currently unavailable, which makes it impossible to reach the real performance of a two-way CVQKD system. We propose an efficient logical layer-based reconciliation method for two-way CVQKD to extract binary information from correlated Gaussian variables. We demonstrate that by operating on the raw-data level, the noise of the quantum channel can be corrected in the scalar space and the reconciliation can be extended to arbitrary high dimensions. The results allow to significantly improve the currently available key rates and transmission distances of two-way CVQKD. We show that by exploiting the proposed adaptive multicarrier modulation scheme, two-way CVQKD can be extended to a range of 160 km over optical fiber with improved tolerable loss and excess noise. The proposed scalar reconciliation can also be applied in one-way systems as well, and can be extended for multiuser communication.

  6. Cascade photonic integrated circuit architecture for electro-optic in-phase quadrature/single sideband modulation or frequency conversion.

    PubMed

    Hasan, Mehedi; Hall, Trevor

    2015-11-01

    A photonic integrated circuit architecture for implementing frequency upconversion is proposed. The circuit consists of a 1×2 splitter and 2×1 combiner interconnected by two stages of differentially driven phase modulators having 2×2 multimode interference coupler between the stages. A transfer matrix approach is used to model the operation of the architecture. The predictions of the model are validated by simulations performed using an industry standard software tool. The intrinsic conversion efficiency of the proposed design is improved by 6 dB over the alternative functionally equivalent circuit based on dual parallel Mach-Zehnder modulators known in the prior art. A two-tone analysis is presented to study the linearity of the proposed circuit, and a comparison is provided over the alternative. The proposed circuit is suitable for integration in any platform that offers linear electro-optic phase modulation such as LiNbO(3), silicon, III-V, or hybrid technology.

  7. Coherent detection of frequency-hopped quadrature modulations in the presence of jamming. I - QPSK and QASK modulations

    NASA Technical Reports Server (NTRS)

    Simon, M. K.; Polydoros, A.

    1981-01-01

    This paper examines the performance of coherent QPSK and QASK systems combined with FH or FH/PN spread spectrum techniques in the presence of partial-band multitone or noise jamming. The worst-case jammer and worst-case performance are determined as functions of the signal-to-background noise ratio (SNR) and signal-to-jammer power ratio (SJR). Asymptotic results for high SNR are shown to have a linear dependence between the jammer's optimal power allocation and the system error probability performance.

  8. Estimating Parameters in the Generalized Graded Unfolding Model: Sensitivity to the Prior Distribution Assumption and the Number of Quadrature Points Used.

    ERIC Educational Resources Information Center

    Roberts, James S.; Donoghue, John R.; Laughlin, James E.

    The generalized graded unfolding model (J. Roberts, J. Donoghue, and J. Laughlin, 1998, 1999) is an item response theory model designed to unfold polytomous responses. The model is based on a proximity relation that postulates higher levels of expected agreement with a given statement to the extent that a respondent is located close to the…

  9. Numerical integration of analytic functions

    NASA Astrophysics Data System (ADS)

    Milovanović, Gradimir V.; Tošić, Dobrilo ð.; Albijanić, Miloljub

    2012-09-01

    A weighted generalized N-point Birkhoff-Young quadrature of interpolatory type for numerical integration of analytic functions is considered. Special cases of such quadratures with respect to the generalized Gegenbauer weight function are derived.

  10. Comparison of numerical techniques for the evaluation of the Doppler broadening functions psi(x,theta) and chi(x,theta)

    NASA Technical Reports Server (NTRS)

    Canright, R. B., Jr.; Semler, T. T.

    1972-01-01

    Several approximations to the Doppler broadening functions psi(x, theta) and chi(x, theta) are compared with respect to accuracy and speed of evaluation. A technique, due to A. M. Turning (1943), is shown to be at least as accurate as direct numerical quadrature and somewhat faster than Gaussian quadrature. FORTRAN 4 listings are included.

  11. Harmonic demodulation of nonstationary shot noise.

    PubMed

    Gray, M B; Stevenson, A J; Bachor, H A; McClelland, D E

    1993-05-15

    We report on experimental demodulation of nonstationary shot noise, which is associated with strongly modulated light. For sinusoidal modulation and demodulation, measurements confirm theoretical predictions of 1.8-dB excess noise in the modulation quadrature and 3-dB noise reduction in the opposite quadrature, relative to the standard quantum limit. Demodulation with a third harmonic produces noise correlated with that which is due to the fundamental. Reducing excess noise by 0.8 dB in the modulation quadrature, by combining the fundamental and third harmonics in a 2:1 ratio, is shown to be feasible. PMID:19802263

  12. Quantum Nondemolition Measurement of a Nonclassical State of a Massive Object

    PubMed Central

    Lecocq, F.; Clark, J. B.; Simmonds, R.W.; Aumentado, J.; Teufel, J. D.

    2016-01-01

    By coupling a macroscopic mechanical oscillator to two microwave cavities, we simultaneously prepare and monitor a nonclassical steady state of mechanical motion. In each cavity, correlated radiation pressure forces induced by two coherent drives engineer the coupling between the quadratures of light and motion. We, first, demonstrate the ability to perform a continuous quantum nondemolition measurement of a single mechanical quadrature at a rate that exceeds the mechanical decoherence rate, while avoiding measurement backaction by more than 13 dB. Second, we apply this measurement technique to independently verify the preparation of a squeezed state in the mechanical oscillator, resolving quadrature fluctuations 20% below the quantum noise. PMID:27057422

  13. An improvement in the numerical integration procedure used in the NASA Marshall engineering thermosphere model

    NASA Technical Reports Server (NTRS)

    Hickey, Michael Philip

    1988-01-01

    A proposed replacement scheme for the integration of the barometric and diffusion equations in the NASA Marshall Engineering Thermosphere (MET) model is presented. This proposed integration scheme is based on Gaussian Quadrature. Extensive numerical testing reveals it to be faster, more accurate and more reliable than the present integration scheme (a modified form of Simpson's Rule) used in the MET model. Numerous graphical examples are provided, along with a listing of a modified form of the MET model in which subroutine INTEGRATE (using Simpson's Rule) is replaced by subroutine GAUSS (which uses Gaussian Quadrature). It is recommended that the Gaussian Quadrature integration scheme, as used here, be used in the MET model.

  14. Low distortion automatic phase control circuit

    NASA Technical Reports Server (NTRS)

    Hauge, G.; Pederson, C. W.

    1972-01-01

    Circuit for generation and demodulation of quadrature double side band signals in frequency division multiplexing system is described. Circuit is designed to produce low distortion automatic phase control. Illustration of circuit and components is included.

  15. Discrete elements method of neutral particle transport

    SciTech Connect

    Mathews, K.A.

    1983-01-01

    A new discrete elements (L/sub N/) transport method is derived and compared to the discrete ordinates S/sub N/ method, theoretically and by numerical experimentation. The discrete elements method is more accurate than discrete ordinates and strongly ameliorates ray effects for the practical problems studied. The discrete elements method is shown to be more cost effective, in terms of execution time with comparable storage to attain the same accuracy, for a one-dimensional test case using linear characteristic spatial quadrature. In a two-dimensional test case, a vacuum duct in a shield, L/sub N/ is more consistently convergent toward a Monte Carlo benchmark solution than S/sub N/, using step characteristic spatial quadrature. An analysis of the interaction of angular and spatial quadrature in xy-geometry indicates the desirability of using linear characteristic spatial quadrature with the L/sub N/ method.

  16. Integrals of the Ising Class

    SciTech Connect

    Bailey, David H.; Borwein, Jonathan M.; Crandall, Richard E.

    2006-06-01

    From an experimental-mathematical perspective we analyze"Ising-class" integrals. Our experimental results involvedextreme-precision, multidimensional quadrature on intricate integrands;thus, highly parallel computation was required.

  17. Quantum frequency up-conversion of continuous variable entangled states

    SciTech Connect

    Liu, Wenyuan; Wang, Ning; Li, Zongyang; Li, Yongmin

    2015-12-07

    We demonstrate experimentally quantum frequency up-conversion of a continuous variable entangled optical field via sum-frequency-generation process. The two-color entangled state initially entangled at 806 and 1518 nm with an amplitude quadrature difference squeezing of 3.2 dB and phase quadrature sum squeezing of 3.1 dB is converted to a new entangled state at 530 and 1518 nm with the amplitude quadrature difference squeezing of 1.7 dB and phase quadrature sum squeezing of 1.8 dB. Our implementation enables the observation of entanglement between two light fields spanning approximately 1.5 octaves in optical frequency. The presented scheme is robust to the excess amplitude and phase noises of the pump field, making it a practical building block for quantum information processing and communication networks.

  18. Asronomical refraction: Computational methods for all zenith angles

    NASA Technical Reports Server (NTRS)

    Auer, L. H.; Standish, E. M.

    2000-01-01

    It is shown that the problem of computing astronomical refraction for any value of the zenith angle may be reduced to a simple, nonsingular, numerical quadrature when the proper choice is made for the independent variable of integration.

  19. Comparisons of Remote And In-situ CME Features

    NASA Astrophysics Data System (ADS)

    Reinard, Alysha; Mulligan, T.; Lynch, B.

    2011-05-01

    We present a comparison of remote and in-situ CME ejecta using data from the Ulysses and SOHO missions. Quadrature occurs when two spacecraft form a 90 degree angle with the Sun. Quadrature studies allow the comparison of visible features of limb CMEs and and in-situ ICME properties. We investigate several events, including so-called "cannibal" CMEs, and compare the relationship between CME morphology and in-situ structures such as magnetic field, composition, and plasma properties.

  20. Discrete ordinates methods in xy geometry with spatially varying angular discretization

    SciTech Connect

    Bal, G.; Warin, X.

    1997-10-01

    The efficiency of a new quadrature rule adapted to the numerical resolution of a neutron transport problem in xy geometry is presented based on the use of the discrete ordinates method for the angular variable. The purpose of introducing this quadrature rule is to couple two different angular discretizations used on two nonoverlapping subdomains, which is useful for performing local refinement. This coupling and some numerical results of source problems are presented.

  1. On the discrete-ordinates method via Case`s solution

    SciTech Connect

    Ganguly, K.; Allen, E.J.; Coskun, E.; Nielsen, S.

    1993-07-01

    In this paper, we have used Case`s analysis of the neutron transport equation to obtain a new set of quadrature coefficients for the discrete-ordinates method. We perform the transport calculations by this set of quadratures, dependent on the medium. We also use the orthogonality relations in the discrete case to derive the full-range formulation of the half-range problem. This solution can, be profitably used in the new discrete-ordinates method.

  2. An improved technique for determining reflection from semi-infinite atmospheres with linearly anisotropic phase functions. [radiative transfer

    NASA Technical Reports Server (NTRS)

    Fricke, C. L.

    1975-01-01

    A solution to the problem of reflection from a semi-infinite atmosphere is presented, based upon Chandrasekhar's H-function method for linearly anisotropic phase functions. A modification to the Gauss quadrature formula which gives about the same accuracy with 10 points as the conventional Gauss quadrature does with 100 points was developed. A computer program achieving this solution is described and results are presented for several illustrative cases.

  3. Updated version of the DOT 4 one- and two-dimensional neutron/photon transport code

    SciTech Connect

    Rhoades, W.A.; Childs, R.L.

    1982-07-01

    DOT 4 is designed to allow very large transport problems to be solved on a wide range of computers and memory arrangements. Unusual flexibilty in both space-mesh and directional-quadrature specification is allowed. For example, the radial mesh in an R-Z problem can vary with axial position. The directional quadrature can vary with both space and energy group. Several features improve performance on both deep penetration and criticality problems. The program has been checked and used extensively.

  4. The multiparty coherent channel and its implementation with linear optics.

    PubMed

    He, Guangqiang; Liu, Taizhi; Tao, Xin

    2013-08-26

    The continuous-variable coherent (conat) channel is a useful resource for coherent communication, supporting coherent teleportation and coherent superdense coding. We extend the conat channel to multiparty conditions by proposing definitions on multiparty position-quadrature and momentum-quadrature conat channel. We additionally provide two methods to implement this channel using linear optics. One method is the multiparty version of coherent communication assisted by entanglement and classical communication (CCAECC). The other is multiparty coherent superdense coding. PMID:24105527

  5. Research on numerical algorithms for large space structures

    NASA Technical Reports Server (NTRS)

    Denman, E. D.

    1981-01-01

    Numerical algorithms for analysis and design of large space structures are investigated. The sign algorithm and its application to decoupling of differential equations are presented. The generalized sign algorithm is given and its application to several problems discussed. The Laplace transforms of matrix functions and the diagonalization procedure for a finite element equation are discussed. The diagonalization of matrix polynomials is considered. The quadrature method and Laplace transforms is discussed and the identification of linear systems by the quadrature method investigated.

  6. Description of arbitrary shaped beams in elliptical cylinder coordinates, by using a plane wave spectrum approach

    NASA Astrophysics Data System (ADS)

    Gouesbet, Gérard; Mees, Loic; Gréhan, Gérard; Ren, Kuan Fang

    1999-03-01

    The description of arbitrary shaped beams in elliptical cylinder coordinates is presented by using a plane wave spectrum approach. It is demonstrated and exemplified that this approach is equivalent to a formally more rigorous approach in terms of distributions. Beam shape coefficients are evaluated by using quadratures. The behavior of these quadratures is discussed in the case of a first-order Davis beam which does not exactly satisfy Maxwell's equations.

  7. Coherent communication with continuous quantum variables

    SciTech Connect

    Wilde, Mark M.; Krovi, Hari; Brun, Todd A.

    2007-06-15

    The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding.

  8. Digital GPS-Signal Processor With P-Code/No-P-Code Option

    NASA Technical Reports Server (NTRS)

    Thomas, J. Brooks; Srinivasan, Jeffrey M.

    1994-01-01

    Size, power, and cost reduced by exploiting commonality. Digital signal processor for Global Positioning System (GPS) receiver set to operate in "code" mode when P code known, or in "codeless" mode when P code not known. In codeless mode, processor performs full-quadrature processing, resulting in signal-to-noise ratio (SNR) 6 dB greater than SNR's of processors not performing at full quadrature.

  9. Mechanical Coupling Error Suppression Technology for an Improved Decoupled Dual-Mass Micro-Gyroscope.

    PubMed

    Yang, Bo; Wang, Xingjun; Deng, Yunpeng; Hu, Di

    2016-04-08

    This paper presents technology for the suppression of the mechanical coupling errors for an improved decoupled dual-mass micro-gyroscope (DDMG). The improved micro-gyroscope structure decreases the moment arm of the drive decoupled torque, which benefits the suppression of the non-ideal decoupled error. Quadrature correction electrodes are added to eliminate the residual quadrature error. The structure principle and the quadrature error suppression means of the DDMG are described in detail. ANSYS software is used to simulate the micro-gyroscope structure to verify the mechanical coupling error suppression effect. Compared with the former structure, simulation results demonstrate that the rotational displacements of the sense frame in the improved structure are substantially suppressed in the drive mode. The improved DDMG structure chip is fabricated by the deep dry silicon on glass (DDSOG) process. The feedback control circuits with quadrature control loops are designed to suppress the residual mechanical coupling error. Finally, the system performance of the DDMG prototype is tested. Compared with the former DDMG, the quadrature error in the improved dual-mass micro-gyroscope is decreased 9.66-fold, and the offset error is decreased 6.36-fold. Compared with the open loop sense, the feedback control circuits with quadrature control loop decrease the bias drift by 20.59-fold and the scale factor non-linearity by 2.81-fold in the ±400°/s range.

  10. Mechanical Coupling Error Suppression Technology for an Improved Decoupled Dual-Mass Micro-Gyroscope.

    PubMed

    Yang, Bo; Wang, Xingjun; Deng, Yunpeng; Hu, Di

    2016-01-01

    This paper presents technology for the suppression of the mechanical coupling errors for an improved decoupled dual-mass micro-gyroscope (DDMG). The improved micro-gyroscope structure decreases the moment arm of the drive decoupled torque, which benefits the suppression of the non-ideal decoupled error. Quadrature correction electrodes are added to eliminate the residual quadrature error. The structure principle and the quadrature error suppression means of the DDMG are described in detail. ANSYS software is used to simulate the micro-gyroscope structure to verify the mechanical coupling error suppression effect. Compared with the former structure, simulation results demonstrate that the rotational displacements of the sense frame in the improved structure are substantially suppressed in the drive mode. The improved DDMG structure chip is fabricated by the deep dry silicon on glass (DDSOG) process. The feedback control circuits with quadrature control loops are designed to suppress the residual mechanical coupling error. Finally, the system performance of the DDMG prototype is tested. Compared with the former DDMG, the quadrature error in the improved dual-mass micro-gyroscope is decreased 9.66-fold, and the offset error is decreased 6.36-fold. Compared with the open loop sense, the feedback control circuits with quadrature control loop decrease the bias drift by 20.59-fold and the scale factor non-linearity by 2.81-fold in the ±400°/s range. PMID:27070616

  11. Development of the Adaptive Collision Source (ACS) method for discrete ordinates

    SciTech Connect

    Walters, W.; Haghighat, A.

    2013-07-01

    We have developed a new collision source method to solve the Linear Boltzmann Equation (LBE) more efficiently by adaptation of the angular quadrature order. The angular adaptation method is unique in that the flux from each scattering source iteration is obtained, with potentially a different quadrature order. Traditionally, the flux from every iteration is combined, with the same quadrature applied to the combined flux. Since the scattering process tends to distribute the radiation more evenly over angles (i.e., make it more isotropic), the quadrature requirements generally decrease with each iteration. This allows for an optimal use of processing power, by using a high order quadrature for the first few iterations that need it, before shifting to lower order quadratures for the remaining iterations. This is essentially an extension of the first collision source method, and we call it the adaptive collision source method (ACS). The ACS methodology has been implemented in the TITAN discrete ordinates code, and has shown a relative speedup of 1.5-2.5 on a test problem, for the same desired level of accuracy. (authors)

  12. Mechanical Coupling Error Suppression Technology for an Improved Decoupled Dual-Mass Micro-Gyroscope

    PubMed Central

    Yang, Bo; Wang, Xingjun; Deng, Yunpeng; Hu, Di

    2016-01-01

    This paper presents technology for the suppression of the mechanical coupling errors for an improved decoupled dual-mass micro-gyroscope (DDMG). The improved micro-gyroscope structure decreases the moment arm of the drive decoupled torque, which benefits the suppression of the non-ideal decoupled error. Quadrature correction electrodes are added to eliminate the residual quadrature error. The structure principle and the quadrature error suppression means of the DDMG are described in detail. ANSYS software is used to simulate the micro-gyroscope structure to verify the mechanical coupling error suppression effect. Compared with the former structure, simulation results demonstrate that the rotational displacements of the sense frame in the improved structure are substantially suppressed in the drive mode. The improved DDMG structure chip is fabricated by the deep dry silicon on glass (DDSOG) process. The feedback control circuits with quadrature control loops are designed to suppress the residual mechanical coupling error. Finally, the system performance of the DDMG prototype is tested. Compared with the former DDMG, the quadrature error in the improved dual-mass micro-gyroscope is decreased 9.66-fold, and the offset error is decreased 6.36-fold. Compared with the open loop sense, the feedback control circuits with quadrature control loop decrease the bias drift by 20.59-fold and the scale factor non-linearity by 2.81-fold in the ±400°/s range. PMID:27070616

  13. Characterization of high order spatial discretizations and lumping techniques for discontinuous finite element SN transport

    SciTech Connect

    Maginot, P. G.; Ragusa, J. C.; Morel, J. E.

    2013-07-01

    We examine several possible methods of mass matrix lumping for discontinuous finite element discrete ordinates transport using a Lagrange interpolatory polynomial trial space. Though positive outflow angular flux is guaranteed with traditional mass matrix lumping in a purely absorbing 1-D slab cell for the linear discontinuous approximation, we show that when used with higher degree interpolatory polynomial trial spaces, traditional lumping does yield strictly positive outflows and does not increase in accuracy with an increase in trial space polynomial degree. As an alternative, we examine methods which are 'self-lumping'. Self-lumping methods yield diagonal mass matrices by using numerical quadrature restricted to the Lagrange interpolatory points. Using equally-spaced interpolatory points, self-lumping is achieved through the use of closed Newton-Cotes formulas, resulting in strictly positive outflows in pure absorbers for odd power polynomials in 1-D slab geometry. By changing interpolatory points from the traditional equally-spaced points to the quadrature points of the Gauss-Legendre or Lobatto-Gauss-Legendre quadratures, it is possible to generate solution representations with a diagonal mass matrix and a strictly positive outflow for any degree polynomial solution representation in a pure absorber medium in 1-D slab geometry. Further, there is no inherent limit to local truncation error order of accuracy when using interpolatory points that correspond to the quadrature points of high order accuracy numerical quadrature schemes. (authors)

  14. Discrete elements method of neutral particle transport. Doctoral thesis

    SciTech Connect

    Mathews, K.A.

    1983-10-01

    A new 'discrete elements' (LN) transport method is derived and compared to the discrete ordinates SN method, theoretically and by numerical experimentation. The discrete elements method is more accurate than discrete ordinates and strongly ameliorates ray effects for the practical problems studied. The discrete elements method is shown to be more cost effective in terms of execution time with comparable storage to attain the same accuracy, for a one-dimensional test case using linear characteristic spatial quadrature. In a two-dimensional test case, a vacuum duct in a shield, LN is more consistently convergent toward a Monte Carlo benchmark solution than SN, using step characteristic spatial quadrature. An analysis of the interaction of angular and spatial quadrature in xy-geometry indicates the desirability of using linear characteristic spatial quadrature with the LN method. The discrete elements method is based on discretizing the Boltzmann equation over a set of elements of angle. The zeroth and first angular moments of the directional flux, over each element, are estimated by numerical quadrature and yield a flux-weighted average streaming direction for the element. (Data for this estimation are fluxes in fixed directions calculated as in SN.)

  15. Bimodal score distributions and the Myers-Briggs Type Indicator: fact or artifact?

    PubMed

    Bess, Tammy L; Harvey, Robert J

    2002-02-01

    We examined Myers-Briggs Type Indicator (MBTI) score distributions computed using item response theory (IRT) to assess the generalizability of earlier bimodality reports that have been cited in support of the "type" versus "trait" view of personality. Using the BILOG IRT program to score a sample of approximately 12,000 individuals who participated in leadership development programs, theta score distributions for the 4 dimensions of the MBTI computed using 10 (the BILOG default) versus 50 quadrature points were compared. Results indicated that past reports of bimodality were artifacts caused by BILOG's default use of a small number of quadrature points; when larger numbers of points were used, score distributions became strongly center-weighted. Although our findings are not supportive of the "type"-based hypothesis, the extremely high correlations between theta scores (rs > .996) suggest that no practical differences would be expected as a function of the number-of-quadrature-points decision. PMID:11936208

  16. Ka-Band SiGe Receiver Front-End MMIC for Transponder Applications

    NASA Technical Reports Server (NTRS)

    Venkatesan, Jaikrishna; Mysoor, Narayan R.; Hashemi, Hassein; Aflatouni, Firooz

    2010-01-01

    A fully integrated, front-end Ka-band monolithic microwave integrated circuit (MMIC) was developed that houses an LNA (low noise amplifier) stage, a down-conversion stage, and output buffer amplifiers. The MMIC design employs a two-step quadrature down-conversion architecture, illustrated in the figure, which results in improved quality of the down-converted IF quadrature signals. This is due to the improved sensitivity of this architecture to amplitude and phase mismatches in the quadrature down-conversion process. Current sharing results in reduced power consumption, while 3D-coupled inductors reduce the chip area. Improved noise figure is expected over previous SiGe-based, frontend designs

  17. Fourth-Order Method for Numerical Integration of Age- and Size-Structured Population Models

    SciTech Connect

    Iannelli, M; Kostova, T; Milner, F A

    2008-01-08

    In many applications of age- and size-structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Because quadratures can be designed with any order of accuracy, one can obtain numerical approximations of the solutions with very fast convergence. In this article, we present a general framework and a specific example of a fourth-order method based on composite Newton-Cotes quadratures for a size-structured population model.

  18. A sublinear-scaling approach to density-functional-theory analysis of crystal defects

    NASA Astrophysics Data System (ADS)

    Ponga, M.; Bhattacharya, K.; Ortiz, M.

    2016-10-01

    We develop a sublinear-scaling method, referred to as MacroDFT, for the study of crystal defects using ab-initio Density Functional Theory (DFT). The sublinear scaling is achieved using a combination of the Linear Scaling Spectral Gauss Quadrature method (LSSGQ) and a Coarse-Graining approach (CG) based on the quasi-continuum method. LSSGQ reformulates DFT and evaluates the electron density without computing individual orbitals. This direct evaluation is possible by recourse to Gaussian quadrature over the spectrum of the linearized Hamiltonian operator. Furthermore, the nodes and weights of the quadrature can be computed independently for each point in the domain. This property is exploited in CG, where fields of interest are computed at selected nodes and interpolated elsewhere. In this paper, we present the MacroDFT method, its parallel implementation and an assessment of convergence and performance by means of test cases concerned with point defects in magnesium.

  19. Non-classical radiation emission by a coherent conductor

    NASA Astrophysics Data System (ADS)

    Forgues, Jean-Charles; Gasse, Gabriel; Lupien, Christian; Reulet, Bertrand

    2016-08-01

    We report experimental evidence that the microwave electromagnetic field generated by a normal conductor, here a tunnel junction placed at ultra-low temperature, can be non-classical. By measuring the quadratures of the electromagnetic field at one or two frequencies in the GHz range, we demonstrate the existence of squeezing as well as entanglement in such radiation. In one experiment, we observe that the variance of one quadrature of the photo-assisted noise generated by the junction goes below its vacuum level. In the second experiment, we demonstrate the existence of correlations between the quadratures taken at two frequencies, which can be stronger than allowed by classical mechanics, proving that the radiation at those two frequencies are entangled.

  20. Waveform Synthesizer For Imaging And Ranging Applications

    DOEpatents

    DUDLEY, PETER A.; [et al

    2004-11-30

    Frequency dependent corrections are provided for quadrature imbalance. An operational procedure filters imbalance effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of quadrature imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  1. Data acquisition system for Doppler radar vital-sign monitor.

    PubMed

    Vergara, Alexander M; Lubecke, Victor M

    2007-01-01

    Automatic gain control (AGC) units increase the dynamic range of a system to compensate for the limited dynamic range of analog to digital converters. This problem is compounded in wireless systems in which large changes in signal strength are effects of a changing environment. These issues are evident in the direct-conversion Doppler radar vital-sign monitor. Utilizing microwave radar signals reflecting off a human subject, a two-channel quadrature receiver can detect periodic movement resulting from cardio-pulmonary activity. The quadrature signal is analyzed using an arctangent demodulation that extracts vital phase information. A data acquisition (DAQ) system is proposed to deal with issues inherent in arctangent demodulation of a quadrature radar signal.

  2. Optimal Signal Filtration in Optical Sensors with Natural Squeezing of Vacuum Noises

    NASA Technical Reports Server (NTRS)

    Gusev, A. V.; Kulagin, V. V.

    1996-01-01

    The structure of optimal receiver is discussed for optical sensor measuring a small displacement of probe mass. Due to nonlinear interaction of the field and the mirror, a reflected wave is in squeezed state (natural squeezing), two quadratures of which are correlated and therefore one can increase signal-to-noise ratio and overcome the SQL. A measurement procedure realizing such correlation processing of two quadratures is clarified. The required combination of quadratures can be produced via mixing of pump field reflected from the mirror with local oscillator phase modulated field in duel-detector homodyne scheme. Such measurement procedure could be useful not only for resonant bar gravitational detector but for laser longbase interferometric detectors as well.

  3. Non-Product Smolyak Grids for Computing Spectra: how and Why?

    NASA Astrophysics Data System (ADS)

    Avila, Gustavo; Carrington, Tucker Carrington, Jr.

    2011-06-01

    Spectra are computed by solving the time-independent Schrödinger equation. If the number of atoms in a molecule is greater than about 4 the dimensionality of the Schrödinger equation makes solution very difficult. Standard discretization strategies for large dimensional systems D≥ 9 yield matrices and vectors that are too large for modern computers. This is the so-called "curse of dimensionality". Both the basis size and quadrature grid size are problems. Several ingenious schemes have been developed in the last decades to reduce the basis size. We have focused on reducing the size of the quadrature grid. The Smolyak algorithm allows one to create non-product quadrature grids with structure. Because of the structure they can be used with pruned product basis sets and the Lanczos algorithm to compute spectra. In this talk we shall explain the nature of these grids and why they are useful for computing spectra.

  4. Polarization quantum properties in a type-II optical parametric oscillator below threshold

    SciTech Connect

    Zambrini, Roberta; Miguel, Maxi San; Gatti, Alessandra; Lugiato, Luigi

    2003-12-01

    We study the far-field spatial distribution of the quantum fluctuations in the transverse profile of the output light beam generated by a type-II optical parametric oscillator below threshold, including the effects of transverse walk-off. We study how quadrature field correlations depend on the polarization. We find spatial Einstein-Podolsky-Rosen entanglement in quadrature-polarization components. For the far-field points not affected by walk-off there is almost complete noise suppression in the proper quadratures difference of any orthogonal polarization components. We show the entanglement of the state of symmetric, intense, or macroscopic, spatial light modes. We also investigate nonclassical polarization properties in terms of the Stokes operators. We find perfect correlations in all Stokes parameters measured in opposite far-field points in the direction orthogonal to the walk-off, while locally the field is unpolarized and we find no polarization squeezing.

  5. Flexible digital modulation and coding synthesis for satellite communications

    NASA Technical Reports Server (NTRS)

    Vanderaar, Mark; Budinger, James; Hoerig, Craig; Tague, John

    1991-01-01

    An architecture and a hardware prototype of a flexible trellis modem/codec (FTMC) transmitter are presented. The theory of operation is built upon a pragmatic approach to trellis-coded modulation that emphasizes power and spectral efficiency. The system incorporates programmable modulation formats, variations of trellis-coding, digital baseband pulse-shaping, and digital channel precompensation. The modulation formats examined include (uncoded and coded) binary phase shift keying (BPSK), quatenary phase shift keying (QPSK), octal phase shift keying (8PSK), 16-ary quadrature amplitude modulation (16-QAM), and quadrature quadrature phase shift keying (Q squared PSK) at programmable rates up to 20 megabits per second (Mbps). The FTMC is part of the developing test bed to quantify modulation and coding concepts.

  6. QPSK-to-2×BPSK wavelength and modulation format conversion through phase-sensitive four-wave mixing in a highly nonlinear optical fiber.

    PubMed

    Da Ros, Francesco; Dalgaard, Kjeld; Lei, Lei; Xu, Jing; Peucheret, Christophe

    2013-11-18

    A phase-sensitive four-wave mixing (FWM) scheme enabling the simultaneous conversion of the two orthogonal quadratures of an optical signal to different wavelengths is demonstrated for the first time under dynamic operation using a highly nonlinear optical fiber (HNLF) as the nonlinear medium. The scheme is first optimized with respect to the power levels and phases of the four phase-coherent pumps. The successful modulation and wavelength conversion of the two complex quadratures of a quadrature phase-shift keying (QPSK) signal to two binary phase-shift keying (BPSK) signals is then demonstrated experimentally with no power penalty at a bit-error-ratio (BER) of 10(-9) compared to direct interferometric demodulation of the QPSK signal.

  7. Low-loss high-speed silicon IQ modulator for QPSK/DQPSK in C and L bands.

    PubMed

    Goi, Kazuhiro; Oka, Akira; Kusaka, Hiroyuki; Terada, Yoshihiro; Ogawa, Kensuke; Liow, Tsung-Yang; Tu, Xiaoguang; Lo, Guo-Qiang; Kwong, Dim-Lee

    2014-05-01

    A low-loss high-speed silicon in-phase (I) quadrature (Q) modulator is designed, fabricated and characterized. The fabricated IQ modulator has a low passive optical loss of 9 dB in C and L bands. Using the modulator, differential quadrature phase-shift keying (DQPSK) transmission at 44.6 Gb/s with differential detection is confirmed with an optical signal-to-noise ratio (OSNR) of 16.3 dB for a bit error rate (BER) of 10(-3) and a dispersion tolerance of -96 to 107 ps/nm. Moreover, in digital coherent detection, quadrature phase-shift keying (QPSK) up to 64 Gb/s are achieved with an OSNR of 11.6-11.8 dB for a BER of 10(-2) at 1530, 1550, and 1610 nm.

  8. Design considerations for a monolithic, GaAs, dual-mode, QPSK/QASK, high-throughput rate transceiver. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Kot, R. A.; Oliver, J. D.; Wilson, S. G.

    1984-01-01

    A monolithic, GaAs, dual mode, quadrature amplitude shift keying and quadrature phase shift keying transceiver with one and two billion bits per second data rate is being considered to achieve a low power, small and ultra high speed communication system for satellite as well as terrestrial purposes. Recent GaAs integrated circuit achievements are surveyed and their constituent device types are evaluated. Design considerations, on an elemental level, of the entire modem are further included for monolithic realization with practical fabrication techniques. Numerous device types, with practical monolithic compatability, are used in the design of functional blocks with sufficient performances for realization of the transceiver.

  9. A radial basis function Galerkin method for inhomogeneous nonlocal diffusion

    DOE PAGES

    Lehoucq, Richard B.; Rowe, Stephen T.

    2016-02-01

    We introduce a discretization for a nonlocal diffusion problem using a localized basis of radial basis functions. The stiffness matrix entries are assembled by a special quadrature routine unique to the localized basis. Combining the quadrature method with the localized basis produces a well-conditioned, sparse, symmetric positive definite stiffness matrix. We demonstrate that both the continuum and discrete problems are well-posed and present numerical results for the convergence behavior of the radial basis function method. As a result, we explore approximating the solution to anisotropic differential equations by solving anisotropic nonlocal integral equations using the radial basis function method.

  10. Calculation of the response of cylindrical targets to collimated beams of particles using one-dimensional adjoint transport techniques. [LMFBR

    SciTech Connect

    Dupree, S. A.

    1980-06-01

    The use of adjoint techniques to determine the interaction of externally incident collimated beams of particles with cylindrical targets is a convenient means of examining a class of problems important in radiation transport studies. The theory relevant to such applications is derived, and a simple example involving a fissioning target is discussed. Results from both discrete ordinates and Monte Carlo transport-code calculations are presented, and comparisons are made with results obtained from forward calculations. The accuracy of the discrete ordinates adjoint results depends on the order of angular quadrature used in the calculation. Reasonable accuracy by using EQN quadratures can be expected from order S/sub 16/ or higher.

  11. New Multithreaded Hybrid CPU/GPU Approach to Hartree-Fock.

    PubMed

    Asadchev, Andrey; Gordon, Mark S

    2012-11-13

    In this article, a new multithreaded Hartree-Fock CPU/GPU method is presented which utilizes automatically generated code and modern C++ techniques to achieve a significant improvement in memory usage and computer time. In particular, the newly implemented Rys Quadrature and Fock Matrix algorithms, implemented as a stand-alone C++ library, with C and Fortran bindings, provides up to 40% improvement over the traditional Fortran Rys Quadrature. The C++ GPU HF code provides approximately a factor of 17.5 improvement over the corresponding C++ CPU code.

  12. Recovering the spectrum of a narrow-band process from syncopated samples

    NASA Technical Reports Server (NTRS)

    Milenkovic, P. H.

    1979-01-01

    A nonuniform sampling strategy, phase quadrature sampling, in which a process of bandwith B is sampled at rate B in each of two channels where the two channels are pi/2 out of phase at frequency B is described. Phase quadrature sampling is a special case of sampling, where the phase between channels is fixed but arbitrary. A simple method for recovering the spectrum of the input process from syncopated samples is derived. The derivation indicates what values of phase between channels result in lossless sampling.

  13. Squeezing of Quantum Noise of Motion in a Micromechanical Resonator.

    PubMed

    Pirkkalainen, J-M; Damskägg, E; Brandt, M; Massel, F; Sillanpää, M A

    2015-12-11

    A pair of conjugate observables, such as the quadrature amplitudes of harmonic motion, have fundamental fluctuations that are bound by the Heisenberg uncertainty relation. However, in a squeezed quantum state, fluctuations of a quantity can be reduced below the standard quantum limit, at the cost of increased fluctuations of the conjugate variable. Here we prepare a nearly macroscopic moving body, realized as a micromechanical resonator, in a squeezed quantum state. We obtain squeezing of one quadrature amplitude 1.1±0.4  dB below the standard quantum limit, thus achieving a long-standing goal of obtaining motional squeezing in a macroscopic object. PMID:26705631

  14. A Heterogeneous Medium Analytical Benchmark

    SciTech Connect

    Ganapol, B.D.

    1999-09-27

    A benchmark, called benchmark BLUE, has been developed for one-group neutral particle (neutron or photon) transport in a one-dimensional sub-critical heterogeneous plane parallel medium with surface illumination. General anisotropic scattering is accommodated through the Green's Function Method (GFM). Numerical Fourier transform inversion is used to generate the required Green's functions which are kernels to coupled integral equations that give the exiting angular fluxes. The interior scalar flux is then obtained through quadrature. A compound iterative procedure for quadrature order and slab surface source convergence provides highly accurate benchmark qualities (4- to 5- places of accuracy) results.

  15. Optical communication with two-photon coherent states. III - Quantum measurements realizable with photoemissive detectors

    NASA Technical Reports Server (NTRS)

    Yuen, H. P.; Shapiro, J. H.

    1980-01-01

    Homodyne detection is shown to achieve the same signal-to-noise ratio as the quantum field quadrature measurement, thus providing a receiver which realizes linear modulation TCS performance gain. The full equivalence of homodyne detection and single-quadrature field measurement is established. A heterodyne configuration which uses a TCS image-band oscillator in addition to the usual coherent state local oscillator is studied. Results are obtained by means of a representation theorem which shows that photoemissive detection realizes the photon flux density measurement.

  16. New Multithreaded Hybrid CPU/GPU Approach to Hartree-Fock.

    PubMed

    Asadchev, Andrey; Gordon, Mark S

    2012-11-13

    In this article, a new multithreaded Hartree-Fock CPU/GPU method is presented which utilizes automatically generated code and modern C++ techniques to achieve a significant improvement in memory usage and computer time. In particular, the newly implemented Rys Quadrature and Fock Matrix algorithms, implemented as a stand-alone C++ library, with C and Fortran bindings, provides up to 40% improvement over the traditional Fortran Rys Quadrature. The C++ GPU HF code provides approximately a factor of 17.5 improvement over the corresponding C++ CPU code. PMID:26605582

  17. Quantum Backaction Evading Measurement of Collective Mechanical Modes

    NASA Astrophysics Data System (ADS)

    Ockeloen-Korppi, C. F.; Damskägg, E.; Pirkkalainen, J.-M.; Clerk, A. A.; Woolley, M. J.; Sillanpää, M. A.

    2016-09-01

    The standard quantum limit constrains the precision of an oscillator position measurement. It arises from a balance between the imprecision and the quantum backaction of the measurement. However, a measurement of only a single quadrature of the oscillator can evade the backaction and be made with arbitrary precision. Here we demonstrate quantum backaction evading measurements of a collective quadrature of two mechanical oscillators, both coupled to a common microwave cavity. The work allows for quantum state tomography of two mechanical oscillators, and provides a foundation for macroscopic mechanical entanglement and force sensing beyond conventional quantum limits.

  18. Noncommutative q -photon-added coherent states

    NASA Astrophysics Data System (ADS)

    Dey, Sanjib; Hussin, Véronique

    2016-05-01

    We construct the photon-added coherent states of a noncommutative harmonic oscillator associated to a q -deformed oscillator algebra. Various nonclassical properties of the corresponding system are explored, first, by studying two different types of higher-order quadrature squeezing, namely, the Hillery type and the Hong-Mandel type, and second, by testing the sub-Poissonian nature of photon statistics in higher order with the help of the correlation function and the Mandel parameter. Also, we compare the behavior of different types of quadrature and photon number squeezing of our system with those of the ordinary harmonic oscillator by considering the same set of parameters.

  19. Einstein-Podolsky-Rosen Correlations via Dissociation of a Molecular Bose-Einstein Condensate

    SciTech Connect

    Kheruntsyan, K.V.; Drummond, P.D.; Olsen, M.K.

    2005-10-07

    Recent experimental measurements of atomic intensity correlations through atom shot noise suggest that atomic quadrature phase correlations may soon be measured with a similar precision. We propose a test of local realism with mesoscopic numbers of massive particles based on such measurements. Using dissociation of a Bose-Einstein condensate of diatomic molecules into bosonic atoms, we demonstrate that strongly entangled atomic beams may be produced which possess Einstein-Podolsky-Rosen (EPR) correlations in field quadratures in direct analogy to the position and momentum correlations originally considered by EPR.

  20. Acquisition Performances Of QPSK Carrier-Tracking Loops

    NASA Technical Reports Server (NTRS)

    Hinedi, Sami M.; Shah, Biren N.

    1992-01-01

    Report presents comparative study of acquisition performances of several types of carrier-signal-tracking loops for reception of quadrature phase-shift keying (QPSK) signals. Loops classified into three types: maximum a-posteriori, (MAP) estimation loop, Costas cross-over loop, and generalized Costas loop. Mathematical models developed. In-phase and quadrature signals generated numerically and processed according to loop algorithms. Results show though MAP loop produces smallest squaring loss at all signal-to-noise ratios, others sometimes exhibit shorter acquisition time and greater probability of acquisition.

  1. Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

    NASA Astrophysics Data System (ADS)

    Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

    2016-02-01

    We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

  2. Simplified coherent receiver with heterodyne detection of eight-channel 50 Gb/s PDM-QPSK WDM signal after 1040 km SMF-28 transmission.

    PubMed

    Zhang, Junwen; Dong, Ze; Yu, Jianjun; Chi, Nan; Tao, Li; Li, Xinying; Shao, Yufeng

    2012-10-01

    We propose and experimentally demonstrate a simplified coherent receiver based on heterodyne detection with only two balanced photodetectors and two analog-to-digital converters. The polarization diversity hybrid can be simplified relative to the conventional one. The detected intermediate frequency signals are first downconverted to baseband with inphase and quadrature separation. Using this scheme, we successfully demonstrated the eight-channel 50 Gb/s polarization division multiplexed quadrature phase shift keying WDM signal with heterodyne detection based on digital signal processing over 1040 km single-mode fiber 28 with erbium-doped fiber amplifier only amplification.

  3. Optical performance monitoring of QPSK data channels by use of neural networks trained with parameters derived from asynchronous constellation diagrams.

    PubMed

    Jargon, Jeffrey A; Wu, Xiaoxia; Choi, Hyeon Yeong; Chung, Yun C; Willner, Alan E

    2010-03-01

    We demonstrate a technique for performance monitoring of quadrature phase-shift keying data channels by simultaneously identifying optical signal-to-noise ratio (OSNR), chromatic dispersion (CD), and polarization-mode dispersion (PMD) using neural networks trained with parameters derived from asynchronous constellation diagrams. A correlation coefficient of 0.987 is reported for a set of testing data from a 40 Gbps return-to-zero, quadrature phase-shift keying (RZ-QPSK) system. The root-mean-square (RMS) errors are 0.77 dB for OSNR, 18.71 ps/nm for CD, and 1.17 ps for DGD.

  4. Transmission and reception of Quad-Carrier QPSK-OFDM signal with blind equalization and overhead-free operation.

    PubMed

    Li, Fan; Zhang, Junwen; Cao, Zizheng; Yu, Jianjun; Li, Xinying; Chen, Lin; Xia, Yan; Chen, Yufei

    2013-12-16

    Quad-Carrier Quadrature Phase Shift Keyed orthogonal frequency division multiplexing (QPSK-OFDM) signal transmission and reception is successfully demonstrated with blind equalization like a 25-ary quadrature amplitude modulation (25-QAM) signal with cascaded multi-modulus algorithm (CMMA) equalization. The phase recovery can be realized with simple Viterbi algorithm and the frequency offset estimation (FOE) should be done with 25-QAM signal before 4-point fast Fourier transform (FFT). 48-Gbit/s Quad-Carrier QPSK-OFDM signal is successfully transmitted over 80-km SMF-28 without penalty.

  5. Blind equalization for dual-polarization two-subcarrier coherent QPSK-OFDM signals.

    PubMed

    Li, Fan; Zhang, Junwen; Yu, Jianjun; Li, Xinying

    2014-01-15

    Dual-polarization two-subcarrier coherent optical orthogonal frequency division multiplexing (CO-OFDM) transmission and reception is successfully demonstrated with blind equalization. A two-subcarrier quadrature phase shift keyed OFDM (QPSK-OFDM) signal can be equalized as a 9-ary quadrature amplitude modulation signal in the time domain with the cascaded multimodulus algorithm equalization method. The nonlinear effect resistance and transmission distance can be enhanced compared with the traditional CO-OFDM transmission system based on frequency equalization with training sequence.

  6. The second Hamiltonian structure for a special case of the Lotka-Volterra equations

    NASA Astrophysics Data System (ADS)

    Bibik, Yu. V.

    2007-08-01

    A special case of the Lotka-Volterra equations is considered for which it is possible to find the second Hamiltonian structure that is complementary to the known one. The form of the new Hamiltonian makes it possible to solve the equations by quadratures, which is the main feature of the case under examination. As a consequence, the period can also be represented by quadratures. In terms of the new variables, the equations of motion admit a mechanical analogy with the oscillations of a mass on a nonlinear spring.

  7. On sampling band-pass signals

    NASA Technical Reports Server (NTRS)

    Sadr, R.; Shahshahani, M.

    1989-01-01

    Four techniques for uniform sampling of band-bass signals are examined. The in-phase and quadrature components of the band-pass signal are computed in terms of the samples of the original band-pass signal. The relative implementation merits of these techniques are discussed with reference to the Deep Space Network (DSN).

  8. Characterization of collective Gaussian attacks and security of coherent-state quantum cryptography.

    PubMed

    Pirandola, Stefano; Braunstein, Samuel L; Lloyd, Seth

    2008-11-14

    We provide a simple description of the most general collective Gaussian attack in continuous-variable quantum cryptography. In the scenario of such general attacks, we analyze the asymptotic secret-key rates which are achievable with coherent states, joint measurements of the quadratures and one-way classical communication.

  9. Optimal cloning for finite distributions of coherent states

    SciTech Connect

    Cochrane, P.T.; Ralph, T.C.; Dolinska, A.

    2004-04-01

    We derive optimal cloning limits for finite Gaussian distributions of coherent states and describe techniques for achieving them. We discuss the relation of these limits to state estimation and the no-cloning limit in teleportation. A qualitatively different cloning limit is derived for a single-quadrature Gaussian quantum cloner.

  10. Hypermedia as a Means for Learning and for Thinking about Learning.

    ERIC Educational Resources Information Center

    Bottino, Rosa M.; Cutugno, Paola; Furinghetti, Fulvia

    This paper reports on a project aimed at designing, implementing, and evaluating a hypermedia system, IPER-3, facing the three classical problems in the history of mathematics (i.e., trisection of the angle, quadrature of the circle, and duplication of the cube). The goal of the project is to study the opportunities offered by this kind of…

  11. How Can Multivariate Item Response Theory Be Used in Reporting of Susbcores? Research Report. ETS RR-10-09

    ERIC Educational Resources Information Center

    Haberman, Shelby J.; Sinharay, Sandip

    2010-01-01

    Recently, there has been increasing interest in reporting diagnostic scores. This paper examines reporting of subscores using multidimensional item response theory (MIRT) models. An MIRT model is fitted using a stabilized Newton-Raphson algorithm (Haberman, 1974, 1988) with adaptive Gauss-Hermite quadrature (Haberman, von Davier, & Lee, 2008). A…

  12. Experimental investigation of nonlinear noise in long-haul 100-Gb/s DP-QPSK communication systems using real-time DSP

    NASA Astrophysics Data System (ADS)

    Gurkin, N. V.; Mikhailov, V.; Nanii, O. E.; Novikov, A. G.; Treshchikov, V. N.; Ubaydullaev, R. R.

    2014-09-01

    Nonlinear noise in 100-Gb/s dual-polarization quadrature phase shift keying transmission has been investigated using a straight-line test bed. The optimal signal power and OSNR margin have been measured in up to 4000 km of G.652-fiber. The results have a good agreement with previously reported models.

  13. Photonic DPASK/QAM signal generation at microwave/millimeter-wave band based on an electro-optic phase modulator.

    PubMed

    Zhang, Ye; Xu, Kun; Zhu, Ran; Li, Jianqiang; Wu, Jian; Hong, Xiaobin; Lin, Jintong

    2008-10-15

    We have proposed and experimentally demonstrated two novel photonic architectures to generate differential-phase amplitude-shift keying and circular quadrature amplitude modulation signals at microwave/millimeter-wave band based on an electro-optic phase modulator. In our proposed schemes, the electronic driven circuits were greatly simplified by employing the photonic vector modulation technique.

  14. Circumstances for Pluto-Charon mutual events in 1989

    NASA Technical Reports Server (NTRS)

    Tholen, David J.; Buie, Marc W.

    1988-01-01

    Circumstances for 90 Pluto-Charon mutual events occurring during the 1989 opposition are presented. It is found that the deepest and longest events will occur near postopposition quadrature in early August. Two new stars are selected as comparison stars for events occurring before opposition in 1989, and it is noted that the 1988 comparison stars should be used for events occurring after opposition.

  15. Quantum cryptography without switching.

    PubMed

    Weedbrook, Christian; Lance, Andrew M; Bowen, Warwick P; Symul, Thomas; Ralph, Timothy C; Lam, Ping Koy

    2004-10-22

    We propose a new coherent state quantum key distribution protocol that eliminates the need to randomly switch between measurement bases. This protocol provides significantly higher secret key rates with increased bandwidths than previous schemes that only make single quadrature measurements. It also offers the further advantage of simplicity compared to all previous protocols which, to date, have relied on switching.

  16. Characterization of collective Gaussian attacks and security of coherent-state quantum cryptography.

    PubMed

    Pirandola, Stefano; Braunstein, Samuel L; Lloyd, Seth

    2008-11-14

    We provide a simple description of the most general collective Gaussian attack in continuous-variable quantum cryptography. In the scenario of such general attacks, we analyze the asymptotic secret-key rates which are achievable with coherent states, joint measurements of the quadratures and one-way classical communication. PMID:19113324

  17. Nonnegative Anisotropic Group Cross Sections: A Hybrid Monte Carlo-Discrete Elements-Discrete Ordinates Approach

    SciTech Connect

    DelGrande, J. Mark; Mathews, Kirk A.

    2001-09-15

    Conventional discrete ordinates transport calculations often produce negative fluxes due to unphysical negative scattering cross sections and/or as artifacts of spatial differencing schemes such as diamond difference. Inherently nonnegative spatial methods, such as the nonlinear, exponential characteristic spatial quadrature, eliminate negative fluxes while providing excellent accuracy, presuming the group-to-group, ordinate-to-ordinate cross sections are all nonnegative. A hybrid approach is introduced in which the flow from spatial cell to spatial cell uses discrete ordinates spatial quadratures, while anisotropic scattering of flux from one energy-angle bin (energy group and discrete element of solid angle) to another such bin is modeled using a Monte Carlo simulation to evaluate the bin-to-bin cross sections. The directional elements tile the sphere of directions; the ordinates for the spatial quadrature are at the centroids of the elements. The method is developed and contrasted with previous schemes for positive cross sections. An algorithm for evaluating the Monte Carlo (MC)-discrete elements (MC-DE) cross sections is described, and some test cases are presented. Transport calculations using MC-DE cross sections are compared with calculations using conventional cross sections and with MCNP calculations. In this testing, the new method is about as accurate as the conventional approach, and often is more accurate. The exponential characteristic spatial quadrature, using the MC-DE cross sections, is shown to provide useful results where linear characteristic and spherical harmonics provide negative scalar fluxes in every cell in a region.

  18. PENTRAN Modeling for Design and Optimization of the Spherical-Shell Transmission Experiments

    SciTech Connect

    Kucukboyaci, Vefa; Haghighat, Alireza; Adams, James M.; Carlson, Allan D.; Grimes, Steven M.; Massey, Thomas N.

    2001-06-17

    The development of PENTRAN models and new methodologies for accurate and efficient simulations for the design and analysis of time-of-flight (TOF) experiments is discussed. The experimental setup measures the transmission of accelerator-generated neutrons (E > 1 MeV) through spherical iron shells using the TOF spectroscopy. The TOF facility includes a collimator, a thick wall with a hole, a TOF tunnel, and a detector placed {approx}620 cm from the neutron source. The goal of the experiment is to correlate the measured spectrum to different types of interactions, such as the total nonelastic-scattering cross section and its various components. The development of several 3-D PENTRAN models and the effectiveness of new quadrature sets are discussed. Initial calculations by means of the developed 3-D discrete ordinates model of the TOF experimental setup using the PENTRAN code with the S{sub 20} level-symmetric quadrature resulted in inaccurate solutions due to ray effects. To overcome this difficulty, new quadrature sets with local refinement capability were used. These new quadrature sets allowed more accurate, yet efficient, calculations. This study indicated that for the TOF model the P{sub n}-T{sub n} (Chebyshev) set with ordinate-splitting yields accurate results in a relatively short time.

  19. L/sub 2/-error estimates for the discrete ordinates method for three-dimensional neutron transport

    SciTech Connect

    Asadzadeh, M.

    1988-02-01

    We prove L/sub 2/-error estimates for the discrete ordinates method for the angular discretization of the three-dimensional neutron transport equation. The analysis is for monoenergetic three-dimensional transport of neutrons in a homogeneous uniform media and isotropic scattering is assumed. A special quadrature rule with relatively uniformly distributed discrete directions is considered.

  20. Performance of the Adaptive Collision Source (ACS) Method for Discrete Ordinates in Parallel Environments

    NASA Astrophysics Data System (ADS)

    Walters, William J.; Haghighat, Alireza

    2014-06-01

    A new collision source method has been developed to solve the Linear Boltzmann Equation (LBE) more efficiently by adaptation of the angular quadrature order. The angular adaptation method is unique in that the flux from each scattering source iteration is obtained separately, with potentially a different quadrature order. This allows for an optimal use of processing power, by using a high order quadrature for the first few iterations that need it, before shifting to lower order quadratures for the remaining iterations. This is essentially an extension of the first collision source method, and we call it the adaptive collision source method (ACS). The ACS methodolog y has been implemented in the TITAN discrete ordinates code, and has shown a speedup of 2-3 on a test problem, with very little loss of accuracy (within a provided adaptive tolerance). Further, the code has been extended to work in parallel environments by angular decomposition. Although the method requires increased parallel communication, tests have shown excellent scalability, with parallel fractions of up to 99%.

  1. A Lagrange-type projector on the real line

    NASA Astrophysics Data System (ADS)

    Mastroianni, G.; Notarangelo, I.

    2010-01-01

    We introduce an interpolation process based on some of the zeros of the m th generalized Freud polynomial. Convergence results and error estimates are given. In particular we show that, in some important function spaces, the interpolating polynomial behaves like the best approximation. Moreover the stability and the convergence of some quadrature rules are proved.

  2. Eigenchannel decomposition for continuous-variable quantum key distribution

    NASA Astrophysics Data System (ADS)

    Gyongyosi, L.; Imre, S.

    2015-03-01

    We develop a singular layer transmission model for continuous-variable quantum key distribution (CVQKD). In CVQKD, the transmit information is carried by continuous-variable (CV) quantum states, particularly by Gaussian random distributed position and momentum quadratures. The reliable transmission of the quadrature components over a noisy link is a cornerstone of CVQKD protocols. The proposed singular layer uses the singular value decomposition of the Gaussian quantum channel, which yields an additional degree of freedom for the phase space transmission. This additional degree of freedom can further be exploited in a multiple-access scenario. The singular layer defines the eigenchannels of the Gaussian physical link, which can be used for the simultaneous reliable transmission of multiple user data streams. We demonstrate the results through the adaptive multicarrier quadrature division-multiuser quadrature allocation (AMQD-MQA) CVQKD multiple-access scheme. We define the singular model of AMQD-MQA and characterize the properties of the eigenchannel interference. The singular layer transmission provides improved simultaneous transmission rates for the users with unconditional security in a multiple-access scenario, particularly in crucial low signal-to-noise ratio regimes.

  3. Hyperon-hyperon interaction based on quark-model baryon-baryon interactions

    NASA Astrophysics Data System (ADS)

    Fukukawa, Kenji

    2014-04-01

    Energy-independent nonlocal Gaussian potential based on the quark-model baryon-baryon interaction is derived by using the Gauss-Legendre quadrature and the Bargmann algebra. The reliability of this potential is examined with respect to the NN, YN and YY phase shifts. This potential reproduces the phase shifts predicted by quark-model baryon-baryon interaction fss2.

  4. Full complex spectrum simultaneous obtaining SD-OCT

    NASA Astrophysics Data System (ADS)

    Gelikonov, Grigory V.; Gelikonov, Valentin M.; Shilyagin, Pavel A.

    2011-03-01

    An efficient technique of simultaneous obtaining of quadrature spectral components of interference signal in spectrometer-based OCT is proposed. The components are obtained in air-spaced non-polarization interferometer by partition of reference beam onto two parts and using an achromatic phase shifter. Several setups of phase sifter are described and compared.

  5. WIRELESS MINE-WIDE TELECOMMUNICATIONS TECHNOLOGY

    SciTech Connect

    Zvi H. Meiksin

    2003-01-01

    We added data transmission to the through-the-earth communications system using quadrature synchronous detection. The results are adequate for computer-to-computer communication as well as for sensor data transmission. We added a feature to the in-mine communications system that allows a person to call an individual, rather than broadcasting, by dialing an identification number before speaking.

  6. Atomic homodyne detection of continuous-variable entangled twin-atom states.

    PubMed

    Gross, C; Strobel, H; Nicklas, E; Zibold, T; Bar-Gill, N; Kurizki, G; Oberthaler, M K

    2011-12-01

    Historically, the completeness of quantum theory has been questioned using the concept of bipartite continuous-variable entanglement. The non-classical correlations (entanglement) between the two subsystems imply that the observables of one subsystem are determined by the measurement choice on the other, regardless of the distance between the subsystems. Nowadays, continuous-variable entanglement is regarded as an essential resource, allowing for quantum enhanced measurement resolution, the realization of quantum teleportation and quantum memories, or the demonstration of the Einstein-Podolsky-Rosen paradox. These applications rely on techniques to manipulate and detect coherences of quantum fields, the quadratures. Whereas in optics coherent homodyne detection of quadratures is a standard technique, for massive particles a corresponding method was missing. Here we report the realization of an atomic analogue to homodyne detection for the measurement of matter-wave quadratures. The application of this technique to a quantum state produced by spin-changing collisions in a Bose-Einstein condensate reveals continuous-variable entanglement, as well as the twin-atom character of the state. Our results provide a rare example of continuous-variable entanglement of massive particles. The direct detection of atomic quadratures has applications not only in experimental quantum atom optics, but also for the measurement of fields in many-body systems of massive particles. PMID:22139418

  7. Carrier recovery techniques on satellite mobile channels

    NASA Technical Reports Server (NTRS)

    Vucetic, B.; Du, J.

    1990-01-01

    An analytical method and a stored channel model were used to evaluate error performance of uncoded quadrature phase shift keying (QPSK) and M-ary phase shift keying (MPSK) trellis coded modulation (TCM) over shadowed satellite mobile channels in the presence of phase jitter for various carrier recovery techniques.

  8. Interferometer for the measurement of plasma density

    DOEpatents

    Jacobson, Abram R.

    1980-01-01

    An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

  9. Nonlinear fiber gyroscope for quantum metrology

    NASA Astrophysics Data System (ADS)

    Luis, Alfredo; Morales, Irene; Rivas, Ángel

    2016-07-01

    We examine the performance of a nonlinear fiber gyroscope for improved signal detection beating the quantum limits of its linear counterparts. The performance is examined when the nonlinear gyroscope is illuminated by practical field states, such as coherent and quadrature squeezed states. This is compared with the case of more ideal probes such as photon-number states.

  10. On the very accurate numerical evaluation of the Generalized Fermi-Dirac Integrals

    NASA Astrophysics Data System (ADS)

    Mohankumar, N.; Natarajan, A.

    2016-10-01

    We indicate a new and a very accurate algorithm for the evaluation of the Generalized Fermi-Dirac Integral with a relative error less than 10-20. The method involves Double Exponential, Trapezoidal and Gauss-Legendre quadratures. For the residue correction of the Gauss-Legendre scheme, a simple and precise continued fraction algorithm is used.

  11. Linearity optimization in a class of analog phase modulators

    NASA Technical Reports Server (NTRS)

    Hearn, C. P.

    1985-01-01

    This paper examines the ultimate modulating linearity attainable with a phase modulation technique based on the linear addition of quadrature phase carrier signals which have been multiplied by precisely defined nonlinear transformations of the modulating signal. Optimum gain coefficients are derived and plotted to permit implementation of analog phase modulators capable of exceptionally good linearity of phase deviations as large as 5 radians.

  12. Lord-Wingersky Algorithm Version 2.0 for Hierarchical Item Factor Models with Applications in Test Scoring, Scale Alignment, and Model Fit Testing. CRESST Report 830

    ERIC Educational Resources Information Center

    Cai, Li

    2013-01-01

    Lord and Wingersky's (1984) recursive algorithm for creating summed score based likelihoods and posteriors has a proven track record in unidimensional item response theory (IRT) applications. Extending the recursive algorithm to handle multidimensionality is relatively simple, especially with fixed quadrature because the recursions can be defined…

  13. Optical Field-Strength Polarization of Two-Mode Single-Photon States

    ERIC Educational Resources Information Center

    Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…

  14. Closed Form Expressions for an Integral Involving the Coulomb Potential

    NASA Astrophysics Data System (ADS)

    Mcisaac, K.; Gottschalk, J. E.; Maslen, E. N.

    1986-12-01

    Expressions for an integral related to the Coulomb potential are given. The expressions are in terms of logarithms and polynomials or logarithms and sums of Legendre polynomials. Identities relating an infinite sum of Legendre polynomials to a finite sum of Legendre polynomials can be deduced. This expression can be used in the domain to t → 1, z → 1 where quadrature fails.

  15. Performance Analysis of Different Modulation Formats in Optical Communication

    NASA Astrophysics Data System (ADS)

    Singh, Kulwinder; Singh, Maninder; Bhatia, Kamaljit Singh; Ryait, Hardeep Singh

    2016-06-01

    In this paper, we demonstrated the variation of different parameters with quadrature amplitude modulation (QAM) and differential phase shift key (DPSK) sequence generator, which generates modulated signals, in data transmission for communication and analysed that how the difference of these sequence generators effect its resonant frequency (RF) value, eye diagram and electrical constellation representation of the system.

  16. Collocation and Galerkin Time-Stepping Methods

    NASA Technical Reports Server (NTRS)

    Huynh, H. T.

    2011-01-01

    We study the numerical solutions of ordinary differential equations by one-step methods where the solution at tn is known and that at t(sub n+1) is to be calculated. The approaches employed are collocation, continuous Galerkin (CG) and discontinuous Galerkin (DG). Relations among these three approaches are established. A quadrature formula using s evaluation points is employed for the Galerkin formulations. We show that with such a quadrature, the CG method is identical to the collocation method using quadrature points as collocation points. Furthermore, if the quadrature formula is the right Radau one (including t(sub n+1)), then the DG and CG methods also become identical, and they reduce to the Radau IIA collocation method. In addition, we present a generalization of DG that yields a method identical to CG and collocation with arbitrary collocation points. Thus, the collocation, CG, and generalized DG methods are equivalent, and the latter two methods can be formulated using the differential instead of integral equation. Finally, all schemes discussed can be cast as s-stage implicit Runge-Kutta methods.

  17. QPSK loop lock detection in the advanced receiver

    NASA Technical Reports Server (NTRS)

    Mileant, A.; Hinedi, S.

    1990-01-01

    The Advanced Receiver (ARX 2) currently being developed uses a Costas crossover loop to acquire and track the phase of an incoming quadrature phase-shift-keyed (QPSK) signal. The performance is described for the QPSK lock detector to be implemented, taking into account the phase jitter in the tracking loop. Simulations are used to verify the results of the analysis.

  18. Simple baseband synchronization scheme for tamed frequency modulation

    NASA Astrophysics Data System (ADS)

    Bellini, S.

    1994-03-01

    A novel carrier and clock synchronization scheme for tamed frequency modulation is presented. It requires one complex sample per bit, like the digital Costas loop for offset in-phase and quadrature modulations, and is based on processing baseband samples of the phase of the received signal. The performance of the synchronizer is assessed by S-curves and simulated acquisition trajectories.

  19. QPSK loop lock detection in the advanced receiver

    NASA Astrophysics Data System (ADS)

    Mileant, A.; Hinedi, S.

    1990-05-01

    The Advanced Receiver (ARX 2) currently being developed uses a Costas crossover loop to acquire and track the phase of an incoming quadrature phase-shift-keyed (QPSK) signal. The performance is described for the QPSK lock detector to be implemented, taking into account the phase jitter in the tracking loop. Simulations are used to verify the results of the analysis.

  20. Toward a Reduced-Wire Readout System for Ultrasound Imaging

    PubMed Central

    Lim, Jaemyung; Arkan, Evren F.; Degertekin, F. Levent; Ghovanloo, Maysam

    2015-01-01

    We present a system-on-a-chip (SoC) for use in high-frequency capacitive micromachined ultrasonic transducer (CMUT) imaging systems. This SoC consists of trans-impedance amplifiers (TIA), delay locked loop (DLL) based clock multiplier, quadrature sampler, and pulse width modulator (PWM). The SoC down converts RF echo signal to baseband by quadrature sampling which facilitates modulation. To send data through a 1.6 m wire in the catheter which has limited bandwidth and is vulnerable to noise, the SoC creates a pseudo-digital PWM signal which can be used for back telemetry or wireless readout of the RF data. In this implementation, using a 0.35-μm std. CMOS process, the TIA and single-to-differential (STD) converter had 45 MHz bandwidth, the quadrature sampler had 10.1 dB conversion gain, and the PWM had 5-bit ENoB. Preliminary results verified front-end functionality, and the power consumption of a TIA, STD, quadrature sampler, PWM, and clock multiplier was 26 mW from a 3 V supply. PMID:25571135

  1. Analysis of synchronous digital-modulation schemes for satellite communication

    NASA Technical Reports Server (NTRS)

    Takhar, G. S.; Gupta, S. C.

    1975-01-01

    The multipath communication channel for space communications is modeled as a multiplicative channel. This paper discusses the effects of multiplicative channel processes on the symbol error rate for quadrature modulation (QM) digital modulation schemes. An expression for the upper bound on the probability of error is derived and numerically evaluated. The results are compared with those obtained for additive channels.

  2. Nonclassicality in phase-number uncertainty relations

    SciTech Connect

    Matia-Hernando, Paloma; Luis, Alfredo

    2011-12-15

    We show that there are nonclassical states with lesser joint fluctuations of phase and number than any classical state. This is rather paradoxical since one would expect classical coherent states to be always of minimum uncertainty. The same result is obtained when we replace phase by a phase-dependent field quadrature. Number and phase uncertainties are assessed using variance and Holevo relation.

  3. Operator Factorization and the Solution of Second-Order Linear Ordinary Differential Equations

    ERIC Educational Resources Information Center

    Robin, W.

    2007-01-01

    The theory and application of second-order linear ordinary differential equations is reviewed from the standpoint of the operator factorization approach to the solution of ordinary differential equations (ODE). Using the operator factorization approach, the general second-order linear ODE is solved, exactly, in quadratures and the resulting…

  4. Discriminator Aids Phase-Lock Acquisition

    NASA Technical Reports Server (NTRS)

    Carson, L. M.; Krasin, F. E.

    1985-01-01

    Voltage-controlled oscillator in suppressed-carrier detector acquire carrier frequency and phase quickly with help of frequency-discriminator arrangement. To obtain discriminator function, filter bandwidth in quadrature (Q) leg of detector is widened with respect to bandwidth of filter in inphase (l) leg.

  5. 112-Gb/s monolithic PDM-QPSK modulator in silicon.

    PubMed

    Dong, Po; Xie, Chongjin; Chen, Long; Buhl, Lawrence L; Chen, Young-Kai

    2012-12-10

    We present a monolithic dual-polarization quadrature phase-shift keying (QPSK) modulator based on a silicon photonic integrated circuit (PIC). This PIC consists of four high-speed silicon modulators, a polarization rotator, and a polarization beam combiner. A 112-Gb/s polarization-division-multiplexed (PDM) QPSK modulation is successfully demonstrated.

  6. QPSK 3R regenerator using a phase sensitive amplifier.

    PubMed

    Perentos, A; Fabbri, S; Sorokina, M; Phillips, I D; Turitsyn, S K; Ellis, A D; Sygletos, S

    2016-07-25

    A black box phase sensitive amplifier based 3R regeneration scheme is proposed for non-return to zero quadrature phase shift keyed formatted signals. Performance improvements of more than 2 dB are achieved at the presence of input phase distortion.

  7. Multiple bit differential detection of offset QPSK

    NASA Technical Reports Server (NTRS)

    Simon, M.

    2003-01-01

    Analogous to multiple symbol differential detection of quadrature phase-shift-keying, a multiple bit differential detection scheme is described for offset QPSK that also exhibits continuous improvement in performance with increasing observation interval. Being derived from maximum-likelihood (ML) considerations, the proposed scheme is purported to be the most power efficient scheme for such a modulation and detection method.

  8. Rectangular QPSK for generation of optical eight-ary phase-shift keying.

    PubMed

    Lu, Guo-Wei; Sakamoto, Takahide; Kawanishi, Tetsuya

    2011-09-12

    Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.

  9. Separation of variables for some systems with a fourth-order integral of motion

    NASA Astrophysics Data System (ADS)

    Grigoryev, Yu. A.; Khudobakhshov, V. A.; Tsiganov, A. V.

    2013-12-01

    We construct separation variables for Yehia's integrable deformations of the Kovalevskaya top and the Chaplygin system on a sphere. In the general case, the corresponding quadratures are given by the Abel-Jacobi map on a two-dimensional submanifold of the Jacobian of a genus-three algebraic curve, which is not hyperelliptic.

  10. Predicting permeability from the characteristic relaxation time and intrinsic formation factor of complex conductivity spectra

    NASA Astrophysics Data System (ADS)

    Revil, A.; Binley, A.; Mejus, L.; Kessouri, P.

    2015-08-01

    Low-frequency quadrature conductivity spectra of siliclastic materials exhibit typically a characteristic relaxation time, which either corresponds to the peak frequency of the phase or the quadrature conductivity or a typical corner frequency, at which the quadrature conductivity starts to decrease rapidly toward lower frequencies. This characteristic relaxation time can be combined with the (intrinsic) formation factor and a diffusion coefficient to predict the permeability to flow of porous materials at saturation. The intrinsic formation factor can either be determined at several salinities using an electrical conductivity model or at a single salinity using a relationship between the surface and quadrature conductivities. The diffusion coefficient entering into the relationship between the permeability, the characteristic relaxation time, and the formation factor takes only two distinct values for isothermal conditions. For pure silica, the diffusion coefficient of cations, like sodium or potassium, in the Stern layer is equal to the diffusion coefficient of these ions in the bulk pore water, indicating weak sorption of these couterions. For clayey materials and clean sands and sandstones whose surface have been exposed to alumina (possibly iron), the diffusion coefficient of the cations in the Stern layer appears to be 350 times smaller than the diffusion coefficient of the same cations in the pore water. These values are consistent with the values of the ionic mobilities used to determine the amplitude of the low and high-frequency quadrature conductivities and surface conductivity. The database used to test the model comprises a total of 202 samples. Our analysis reveals that permeability prediction with the proposed model is usually within an order of magnitude from the measured value above 0.1 mD. We also discuss the relationship between the different time constants that have been considered in previous works as characteristic relaxation time, including

  11. Accuracy analysis of high-order lattice Boltzmann models for rarefied gas flows

    NASA Astrophysics Data System (ADS)

    Meng, Jianping; Zhang, Yonghao

    2011-02-01

    In this work, we have theoretically analyzed and numerically evaluated the accuracy of high-order lattice Boltzmann (LB) models for capturing non-equilibrium effects in rarefied gas flows. In the incompressible limit, the LB equation is shown to be able to reduce to the linearized Bhatnagar-Gross-Krook (BGK) equation. Therefore, when the same Gauss-Hermite quadrature is used, LB method closely resembles the discrete velocity method (DVM). In addition, the order of Hermite expansion for the equilibrium distribution function is found not to be directly correlated with the approximation order in terms of the Knudsen number to the BGK equation for incompressible flows. Meanwhile, we have numerically evaluated the LB models for a standing-shear-wave problem, which is designed specifically for assessing model accuracy by excluding the influence of gas molecule/surface interactions at wall boundaries. The numerical simulation results confirm that the high-order terms in the discrete equilibrium distribution function play a negligible role in capturing non-equilibrium effect for low-speed flows. By contrast, appropriate Gauss-Hermite quadrature has the most significant effect on whether LB models can describe the essential flow physics of rarefied gas accurately. Our simulation results, where the effect of wall/gas interactions is excluded, can lead to conclusion on the LB modeling capability that the models with higher-order quadratures provide more accurate results. For the same order Gauss-Hermite quadrature, the exact abscissae will also modestly influence numerical accuracy. Using the same Gauss-Hermite quadrature, the numerical results of both LB and DVM methods are in excellent agreement for flows across a broad range of the Knudsen numbers, which confirms that the LB simulation is similar to the DVM process. Therefore, LB method can offer flexible models suitable for simulating continuum flows at the Navier-Stokes level and rarefied gas flows at the linearized

  12. Cross-Spectra Over the Sea from Observations and Mesoscale Modelling

    NASA Astrophysics Data System (ADS)

    Vincent, C. L.; Larsén, X. G.; Larsen, S. E.; Sørensen, P.

    2013-02-01

    Cospectra and quadrature spectra are calculated for six pairs of tall offshore measurement masts near the Horns Rev I wind farm in the Danish North Sea and the Nysted wind farm in the Baltic sea. The mast-pairs are separated from one another by horizontal distances of 2.13-12.4 km. Cospectra and quadrature spectra for the two sites are classified in terms of the angle between the mean wind direction and the line connecting each pair of masts. The frequency axes of the spectra are normalized to remove the effect of mean wind speed and separation distance. Results indicate a larger contribution to the quadrature spectrum for flow from the sea than for flow from the land, and the patterns in the spectra are clearer and better defined for Horns Rev I (which has a long uninterrupted sea-fetch from the west) than for Nysted (which is surrounded by a more complicated coastline). The analysis is replicated based on 3-month simulations using the weather research and forecasting (WRF) numerical model with a horizontal grid spacing of 2 km. For the sea-fetch directions, good agreement in spectral properties between the model and observations is found. Analytical expressions based on the properties of the cross-correlation function and an exponentially decaying coherence function are fitted to the normalized cospectra and quadrature spectra. The expressions are shown to be a good fit to the spectra calculated from the WRF simulations and to the observed spectra for directions with a long sea-fetch, which suggests that to a good approximation, the average cospectra and quadrature spectra over the sea can be written as functions of frequency, mean wind speed, separation distance and the angle between the wind direction and the orientation of the masts.

  13. Performance Analysis for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Tholhath, S.; Tiong, T. C.

    2015-04-01

    Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configurations are considered. This paper has outlined various estimation techniques to increase the throughput of the LTE network by simulating the estimation techniques with various parameters in the LTE downlink mode 4 (spatial multiplexing). Three techniques i.e. channel estimation technique, estimation of channel models and MIMO receiver algorithm are simulated to provide the ideal LTE wireless communication system.

  14. Adaptive Modulation and Coding for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Hadi, S. S.; Tiong, T. C.

    2015-04-01

    Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configuration is studied. With channel station information feedback from the mobile receiver to the base station transmitter, adaptive modulation and coding can be applied to adapt to the mobile wireless channels condition to increase spectral efficiencies without increasing bit error rate in noisy channels. In High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS), AMC can be used to choose modulation types and forward error correction (FEC) coding rate.

  15. Accurate solution of the Dirac equation on Lagrange meshes.

    PubMed

    Baye, Daniel; Filippin, Livio; Godefroid, Michel

    2014-04-01

    The Lagrange-mesh method is an approximate variational method taking the form of equations on a grid because of the use of a Gauss quadrature approximation. With a basis of Lagrange functions involving associated Laguerre polynomials related to the Gauss quadrature, the method is applied to the Dirac equation. The potential may possess a 1/r singularity. For hydrogenic atoms, numerically exact energies and wave functions are obtained with small numbers n+1 of mesh points, where n is the principal quantum number. Numerically exact mean values of powers -2 to 3 of the radial coordinate r can also be obtained with n+2 mesh points. For the Yukawa potential, a 15-digit agreement with benchmark energies of the literature is obtained with 50 or fewer mesh points.

  16. Cryptographie quantique à variables continues

    NASA Astrophysics Data System (ADS)

    Bencheikh, K.; Jankovic, A.; Symul, T.; Levenson, J. A.

    2002-06-01

    Nous avons élaboré un protocole de cryptographie quantique qui permet de générer et de distribuer une clé secrète aléatoire. Le protocole repose sur l'utilisation de paires de champs électromagnétiques dont les quadratures présentent des corrélations quantiques de type Einstein-Podolsky-Rosen. Les fluctuations quantiques instantanése constituent les bits aléatoires de la clé secrète, et la dégradation irréversible des corrélations quantiques des quadratures causée par une tierce personne permet de la détecter et de garantir la sécurité d'échange.

  17. Feedback-Enhanced Parametric Squeezing of Mechanical Motion

    NASA Astrophysics Data System (ADS)

    Vinante, A.; Falferi, P.

    2013-11-01

    We present a single-quadrature feedback scheme able to overcome the conventional 3 dB limit on parametric squeezing. The method is experimentally demonstrated in a micromechanical system based on a cantilever with a magnetic tip. The cantilever is detected at low temperature by a SQUID susceptometer, while parametric pumping is obtained by modulating the magnetic field gradient at twice the cantilever frequency. A maximum squeezing of 11.5 dB and 11.3 dB is observed, respectively, in the response to a sinusoidal test signal and in the thermomechanical noise. So far, the maximum squeezing factor is limited only by the maximum achievable parametric modulation. The proposed technique might be used to squeeze one quadrature of a mechanical resonator below the quantum noise level, even without the need for a quantum limited detector.

  18. Low Scaling Algorithms for the Random Phase Approximation: Imaginary Time and Laplace Transformations.

    PubMed

    Kaltak, Merzuk; Klimeš, Jiří; Kresse, Georg

    2014-06-10

    In this paper, we determine efficient imaginary frequency and imaginary time grids for second-order Møller-Plesset (MP) perturbation theory. The least-squares and Minimax quadratures are compared for periodic systems, finding that the Minimax quadrature performs slightly better for the considered materials. We show that the imaginary frequency grids developed for second order also perform well for the correlation energy in the direct random phase approximation. Furthermore, we show that the polarizabilities on the imaginary time axis can be Fourier-transformed to the imaginary frequency domain, since the time and frequency Minimax grids are dual to each other. The same duality is observed for the least-squares grids. The transformation from imaginary time to imaginary frequency allows one to reduce the time complexity to cubic (in system size), so that random phase approximation (RPA) correlation energies become accessible for large systems.

  19. Motion detector and analyzer

    DOEpatents

    Unruh, W.P.

    1987-03-23

    Method and apparatus are provided for deriving positive and negative Doppler spectrum to enable analysis of objects in motion, and particularly, objects having rotary motion. First and second returned radar signals are mixed with internal signals to obtain an in-phase process signal and a quadrature process signal. A broad-band phase shifter shifts the quadrature signal through 90/degree/ relative to the in-phase signal over a predetermined frequency range. A pair of signals is output from the broad-band phase shifter which are then combined to provide a first side band signal which is functionally related to a negative Doppler shift spectrum. The distinct positive and negative Doppler spectra may then be analyzed for the motion characteristics of the object being examined.

  20. An increase in the transmission efficiency of an RF fiber-optic line using the working point of an external modulator

    NASA Astrophysics Data System (ADS)

    Petrov, A. N.; Tronev, A. V.; Lebedev, V. V.; Il'ichev, I. V.; Velichko, E. N.; Shamrai, A. V.

    2015-05-01

    A method to increase the transmission efficiency of an analog fiber-optic line using a shift of the working point of an external modulator toward minimum transmission is proposed. The method is based on an increase in the signal contrast owing to the suppression of the constant component and the application of an erbium-fiber amplifier in the near-saturation mode. An increase in the transmission (up to 5 dB) in comparison with the transmission corresponding to the quadrature working point is demonstrated. An increase in the nonlinear distortion factor due to the shift of the modulator from the quadrature working point is analyzed. An increase in the nonlinear distortions under the conditions for the maximum transmission is no greater than 0.5%. A theoretical model is developed to describe the experimental effects. The theoretical results are in good agreement with the experimental data.

  1. On Accuracy Order of Fourier Coefficients Computation for Periodic Signal Processing Models

    NASA Astrophysics Data System (ADS)

    Korytov, I. V.; Golosov, S. E.

    2016-08-01

    The article is devoted to construction piecewise constant functions for modelling periodic signal. The aim of the paper is to suggest a way to avoid discontinuity at points where waveform values are obtained. One solution is to introduce shifted step function whose middle points within its partial intervals coincide with points of observation. This means that large oscillations of Fourier partial sums move to new jump discontinuities where waveform values are not obtained. Furthermore, any step function chosen to model periodic continuous waveform determines a way to calculate Fourier coefficients. In this case, the technique is certainly a weighted rectangular quadrature rule. Here, the weight is either unit or trigonometric. Another effect of the solution consists in following. The shifted function leads to application midpoint quadrature rules for computing Fourier coefficients. As a result the formula for zero coefficient transforms into trapezoid rule. In the same time, the formulas for other coefficients remain of rectangular type.

  2. Non-contact displacement estimation using Doppler radar.

    PubMed

    Gao, Xiaomeng; Singh, Aditya; Yavari, Ehsan; Lubecke, Victor; Boric-Lubecke, Olga

    2012-01-01

    Non-contact Doppler radar has been used extensively for detection of physiological motion. Most of the results published to date have been focused on estimation of the physiological rates, such as respiratory rate and heart rate, with CW and modulated waveforms in various settings. Accurate assessment of chest displacement may take this type of monitoring to the new level, by enabling the estimation of associated cardiopulmonary volumes, and possibly pulse pressure. To obtain absolute chest displacement with highest precision, full nonlinear phase demodulation of the quadrature radar outputs must be performed. The accuracy of this type of demodulation is limited by the drifting received RF power, varying dc offset, and channel quadrature imbalance. In this paper we demonstrate that if relatively large motion is used to calibrate the system, smaller motion displacement may be acquired with the accuracy on the order of 30 µm. PMID:23366212

  3. A fast conservative spectral solver for the nonlinear Boltzmann collision operator

    SciTech Connect

    Gamba, Irene M.; Haack, Jeffrey R.; Hu, Jingwei

    2014-12-09

    We present a conservative spectral method for the fully nonlinear Boltzmann collision operator based on the weighted convolution structure in Fourier space developed by Gamba and Tharkabhushnanam. This method can simulate a broad class of collisions, including both elastic and inelastic collisions as well as angularly dependent cross sections in which grazing collisions play a major role. The extension presented in this paper consists of factorizing the convolution weight on quadrature points by exploiting the symmetric nature of the particle interaction law, which reduces the computational cost and memory requirements of the method to O(M{sup 2}N{sup 4}logN) from the O(N{sup 6}) complexity of the original spectral method, where N is the number of velocity grid points in each velocity dimension and M is the number of quadrature points in the factorization, which can be taken to be much smaller than N. We present preliminary numerical results.

  4. Improved discrete ordinates calculations for an approximate model of neutral particle transport in ducts

    SciTech Connect

    Garcia, R.D.M.; Ono, S.

    1999-09-01

    An improved implementation of the discrete ordinates method for computing neutral particle transport in ducts is presented. The considered one-dimensional model makes use of two basic functions to represent the transverse and azimuthal dependencies of the particle angular flux in the duct. It is shown that if the problem is decomposed into uncollided and collided problems prior to using the discrete ordinates approximation, the number of ordinates necessary to achieve a desired degree of accuracy in the solution can be greatly reduced, especially for long ducts with significant wall absorption. Further savings in computer time can be attained by employing a composite quadrature based on a (nonstandard) half-range quadrature that can be generated in an effective and efficient way with one of the classical methods in the constructive theory of orthogonal polynomials.

  5. On the equivalence between the discrete ordinates and the spherical harmonics methods in radiative transfer

    SciTech Connect

    Barichello, L.B.; Siewert, C.E.

    1998-09-01

    In this work concerning steady-state radiative-transfer calculations in plane-parallel media, the equivalence between the discrete ordinates method and the spherical harmonics method is proved. More specifically, it is shown that for standard radiative-transfer problems without the imposed restriction of azimuthal symmetry the two methods yield identical results for the radiation intensity when the quadrature scheme for the discrete ordinates method is defined by the zeros of the associated Legendre functions and when generalized Mark boundary conditions are used to define the spherical harmonics solution. It is also shown that, with these choices for a quadrature scheme and for the boundary conditions, the two methods can be formulated so as to require the same computational effort. Finally a justification for using the generalized Mark boundary conditions in the spherical harmonics solution is given.

  6. Boltzmann-Fokker-Planck calculations using standard discrete-ordinates codes

    SciTech Connect

    Morel, J.E.

    1987-01-01

    The Boltzmann-Fokker-Planck (BFP) equation can be used to describe both neutral and charged-particle transport. Over the past several years, the author and several collaborators have developed methods for representing Fokker-Planck operators with standard multigroup-Legendre cross-section data. When these data are input to a standard S/sub n/ code such as ONETRAN, the code actually solves the Boltzmann-Fokker-Planck equation rather than the Boltzmann equation. This is achieved wihout any modification to the S/sub n/ codes. Because BFP calculations can be more demanding from a numerical viewpoint than standard neutronics calculations, we have found it useful to implement new quadrature methods ad convergence acceleration methods in the standard discrete-ordinates code, ONETRAN. We discuss our BFP cross-section representation techniques, our improved quadrature and acceleration techniques, and present results from BFP coupled electron-photon transport calculations performed with ONETRAN. 19 refs., 7 figs.

  7. Development of a discrete ordinates code system for unstructured meshes of tetrahedral cells, with serial and parallel implementations

    SciTech Connect

    Miller, R.L.

    1998-11-01

    A numerically stable, accurate, and robust form of the exponential characteristic (EC) method, used to solve the time-independent linearized Boltzmann Transport Equation, is derived using direct affine coordinate transformations on unstructured meshes of tetrahedra. This quadrature, as well as the linear characteristic (LC) spatial quadrature, is implemented in the transport code, called TETRAN. This code solves multi-group neutral particle transport problems with anisotropic scattering and was parallelized using High Performance Fortran and angular domain decomposition. A new, parallel algorithm for updating the scattering source is introduced. The EC source and inflow flux coefficients are efficiently evaluated using Broyden`s rootsolver, started with special approximations developed here. TETRAN showed robustness, stability and accuracy on a variety of challenging test problems. Parallel speed-up was observed as the number of processors was increased using an IBM SP computer system.

  8. Moment-Preserving SN Discretizations for the One-Dimensional Fokker-Planck Equation

    SciTech Connect

    Warsa, James S.; Prinja, Anil K.

    2012-06-14

    The Fokker-Planck equation: (1) Describes the transport and interactions of charged particles, (2) Many small-angle scattering collisions, (3) Asymptotic limit of the Boltzmann equation (Pomraning, 1992), and (4) The Boltzmann collision operator becomes the angular Laplacian. SN angular discretization: (1) Angular flux is collocated at the SN quadrature points, (2) The second-order derivatives in the Laplacian term must be discretized, and (3) Weighted finite-difference method preserves zeroth and first moments (Morel, 1985). Moment-preserving methods: (1) Collocate the Fokker-Planck operator at the SN quadrature points, (2) Develop several related and/or equivalent methods, and (3) Motivated by discretizations for the angular derivative appearing in the transport equation in one-dimensional spherical coordinates.

  9. A code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check codes

    NASA Astrophysics Data System (ADS)

    Bai, Cheng-lin; Cheng, Zhi-hui

    2016-09-01

    In order to further improve the carrier synchronization estimation range and accuracy at low signal-to-noise ratio ( SNR), this paper proposes a code-aided carrier synchronization algorithm based on improved nonbinary low-density parity-check (NB-LDPC) codes to study the polarization-division-multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system performance in the cases of quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) modes. The simulation results indicate that this algorithm can enlarge frequency and phase offset estimation ranges and enhance accuracy of the system greatly, and the bit error rate ( BER) performance of the system is improved effectively compared with that of the system employing traditional NB-LDPC code-aided carrier synchronization algorithm.

  10. Symbol rate identification for auxiliary amplitude modulation optical signal

    NASA Astrophysics Data System (ADS)

    Wei, Junyu; Dong, Zhi; Huang, Zhiping; Zhang, Yimeng

    2016-09-01

    In this paper, we creatively propose and demonstrate a method for symbol rate identification (SRI) of auxiliary amplitude modulation (AAM) optical signal based on asynchronous delay-tap sampling (ADTS) and average magnitude difference function (AMDF). The method can accurately estimate symbol rate and has large transmission impairments tolerance. Furthermore, it can be realized in the digital signal processor (DSP) with low logical resources because of multiplication-free. In order to improve the accuracy of SRI, the peak to valley ratio (PTVR) of AMDF is introduced into our method for blind chromatic dispersion (CD) compensation. The results of the numerical simulations show that the overall maximum SRI error is smaller 0.079% for return-to-zero (RZ) on-off keying (OOK), RZ differential phase-shift keying (DPSK), RZ differential quadrature phase-shift keying (DQPSK) and RZ 16-ary quadrature amplitude modulation (QAM) with 50% duty cycles.

  11. A full-duplex optical access system with hybrid 64/16/4QAM-OFDM downlink

    NASA Astrophysics Data System (ADS)

    He, Chao; Tan, Ze-fu; Shao, Yu-feng; Cai, Li; Pu, He-sheng; Zhu, Yun-le; Huang, Si-si; Liu, Yu

    2016-09-01

    A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation (64/16/4QAM) orthogonal frequency division multiplexing (OFDM) optical signal is for downstream transmission and non-return-to-zero (NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase (I/Q) modulation based on Mach-Zehnder modulator (MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio ( BER) less than hardware decision forward error correction (HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber (SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several subchannels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication.

  12. Storage and conversion of quantum-statistical properties of light in resonant quantum memory on a tripod atomic configuration

    NASA Astrophysics Data System (ADS)

    Losev, A. S.; Tikhonov, K. S.; Golubeva, T. Yu; Golubev, Yu M.

    2016-10-01

    We have considered theoretically the feasibility of broadband quantum memory based on the resonant tripod-type atomic configuration. In this case, the writing of a signal field is carried out simultaneously into two channels, and characterized by an excitation of two spin waves of the atomic ensemble. With simultaneous read out from both channels, quantum properties of the original signal are mapped onto the retrieval pulse no worse than in the case of memory based on a Λ-type atomic configuration. At the same time new possibilities are opened up for the manipulation of quantum states associated with sequential reading out (and/or sequential writing) of signal pulses. For example, a pulse in the squeezed state is converted into two partially entangled pulses with partially squeezed quadratures. Alternatively, two independent signal pulses with orthogonally squeezed quadratures can be converted into two entangled pulses.

  13. State-constrained booster trajectory solutions via finite elements and shooting

    NASA Technical Reports Server (NTRS)

    Bless, Robert R.; Hodges, Dewey H.; Seywald, Hans

    1993-01-01

    This paper presents an extension of a FEM formulation based on variational principles. A general formulation for handling internal boundary conditions and discontinuities in the state equations is presented, and the general formulation is modified for optimal control problems subject to state-variable inequality constraints. Solutions which only touch the state constraint and solutions which have a boundary arc of finite length are considered. Suitable shape and test functions are chosen for a FEM discretization. All element quadrature (equivalent to one-point Gaussian quadrature over each element) may be done in closed form. The final form of the algebraic equations is then derived. A simple state-constrained problem is solved. Then, for a practical application of the use of the FEM formulation, a launch vehicle subject to a dynamic pressure constraint (a first-order state inequality constraint) is solved. The results presented for the launch-vehicle trajectory have some interesting features, including a touch-point solution.

  14. Two-color continuous-variable quantum entanglement in a singly resonant optical parametric oscillator

    SciTech Connect

    Cuozzo, Domenico; Oppo, Gian-Luca

    2011-10-15

    We apply the input-output theory of optical cavities to formulate a quantum treatment of a continuous-wave singly resonant optical parametric oscillator. This case is mainly relevant to highly nondegenerate signal and idler modes. We show that both intensity and quadrature squeezing are present and that the maximum noise reduction below the standard quantum limit is the same at the signal and idler frequencies as in the doubly resonant case. As the threshold of oscillation is approached, however, the intensity-difference and quadrature spectra display a progressive line narrowing which is absent in the balanced doubly resonant case. By use of the separability criterion for continuous variables, the signal-idler state is found to be entangled over wide ranges of the parameters. We show that attainable levels of squeezing and entanglement make singly resonant configurations ideal candidates for two-color quantum information processes, because of their ease of tuning in experimental realizations.

  15. Communication: An efficient algorithm for evaluating the Breit and spin-spin coupling integrals

    NASA Astrophysics Data System (ADS)

    Shiozaki, Toru

    2013-03-01

    We present an efficient algorithm for evaluating a class of two-electron integrals of the form {r}_{12}⊗ {r}_{12}/r_{12}^n over one-electron Gaussian basis functions. The full Breit interaction in four-component relativistic theories beyond the Gaunt term is such an operator with n = 3. Another example is the direct spin-spin coupling term in the quasi-relativistic Breit-Pauli Hamiltonian (n = 5). These integrals have been conventionally evaluated by expensive derivative techniques. Our algorithm is based on tailored Gaussian quadrature, similar to the Rys quadrature for electron repulsion integrals (ERIs), and can utilize the so-called horizontal recurrence relation to reduce the computational cost. The CPU time for computing all six Cartesian components of the Breit or spin-spin coupling integrals is found to be only 3 to 4 times that of the ERI evaluation.

  16. Communication: An efficient algorithm for evaluating the Breit and spin-spin coupling integrals.

    PubMed

    Shiozaki, Toru

    2013-03-21

    We present an efficient algorithm for evaluating a class of two-electron integrals of the form r12⊗r12/r12(n) over one-electron Gaussian basis functions. The full Breit interaction in four-component relativistic theories beyond the Gaunt term is such an operator with n = 3. Another example is the direct spin-spin coupling term in the quasi-relativistic Breit-Pauli Hamiltonian (n = 5). These integrals have been conventionally evaluated by expensive derivative techniques. Our algorithm is based on tailored Gaussian quadrature, similar to the Rys quadrature for electron repulsion integrals (ERIs), and can utilize the so-called horizontal recurrence relation to reduce the computational cost. The CPU time for computing all six Cartesian components of the Breit or spin-spin coupling integrals is found to be only 3 to 4 times that of the ERI evaluation. PMID:23534619

  17. Speeding up DFT: A faster method for integrating band energy in SCF cycles

    NASA Astrophysics Data System (ADS)

    Burbidge, Matthew M.; Jorgensen, Jeremy J.; Rosenbrock, Conrad W.; Thomas, Derek C.; Hess, Bret C.; Forcade, Rodney W.; Curtarolo, Stefano; Hart, Gus L. W.

    2015-03-01

    Typically in SCF cycles, a ``rectangle rule'' is used on uniformly spaced points (Monk Pack meshes)1 to integrate the band energy. The use of rectangles is motivated by their fast convergence when used on the fully occupied bands of semiconductors. Unfortunately integration with rectangles is extremely inefficient for metals. This motivates the use of gauss quadrature (or other higher order methods) for integrating the band energy. As we show, however, even in the case of semiconductors where the rectangle convergence is extremely efficient, higher order methods are still more efficient. The savings in semiconductors alone are sufficient to motivate the implementation of a higher order method in current DFT codes. Even though higher order quadrature methods were discussed immediately following the original Monkhorst and Pack1 paper, we revisit the issue in light of modern DFT calculations. MMB acknowledges support by NSF (DMR-0908753). JJJ, CWR, DCT, RWF, SC, GLWH was supported by ONR (MURI N00014-13-1-0635).

  18. Non-contact displacement estimation using Doppler radar.

    PubMed

    Gao, Xiaomeng; Singh, Aditya; Yavari, Ehsan; Lubecke, Victor; Boric-Lubecke, Olga

    2012-01-01

    Non-contact Doppler radar has been used extensively for detection of physiological motion. Most of the results published to date have been focused on estimation of the physiological rates, such as respiratory rate and heart rate, with CW and modulated waveforms in various settings. Accurate assessment of chest displacement may take this type of monitoring to the new level, by enabling the estimation of associated cardiopulmonary volumes, and possibly pulse pressure. To obtain absolute chest displacement with highest precision, full nonlinear phase demodulation of the quadrature radar outputs must be performed. The accuracy of this type of demodulation is limited by the drifting received RF power, varying dc offset, and channel quadrature imbalance. In this paper we demonstrate that if relatively large motion is used to calibrate the system, smaller motion displacement may be acquired with the accuracy on the order of 30 µm.

  19. 50 Gbit/s real-time test environment for integrated photonic DQPSK receivers

    NASA Astrophysics Data System (ADS)

    Föhn, T.; Fischer, C.; Berroth, M.

    2014-11-01

    In this paper an FPGA-based test system for high-speed transmission experiments with integrated photonic receivers is presented. Pseudorandom binary sequences are generated inside the FPGA and encoded as either differential quadrature phase shift keying (DQPSK) or quadrature phase shift keying (QPSK) signals. The DQPSK encoder uses a 64-fold parallel-prefix-layers architecture for real-time operation which allows for a maximum internal encoder data rate of 64 Gbit/s. Two-fold parallel data streams of I and Q signals suitable for driving an optical IQ-modulator can be transmitted and received by four 12.5 Gbit/s transceivers. Integrated bit error testers are used to determine bit error rates in real-time.

  20. Third and fourth virial coefficients for hard disks in narrow channels

    NASA Astrophysics Data System (ADS)

    Mon, K. K.

    2014-06-01

    The third (B3) and fourth (B4) virial coefficients of hard disks in narrow channels have been evaluated accurately by Gaussian quadrature for a range of channel widths (2Rp), Rp < ({√{3}} + 2)/4= 0.9330... (in units of the hard disk diameter). These widths correspond to the important regime of fluids in single file formations with only nearest-neighbor interactions. Accurate results are obtained by using N-point Gaussian quadrature and extrapolating to the infinite N limits. Since not much is known about these B3 and B4, our new results should provide guidance for exact calculations of the virial coefficients and benchmarks for other numerical methods.

  1. Multistep and Multistage Boundary Integral Methods for the Wave Equation

    NASA Astrophysics Data System (ADS)

    Banjai, Lehel

    2009-09-01

    We describe how time-discretized wave equation in a homogeneous medium can be solved by boundary integral methods. The time discretization can be a multistep, Runge-Kutta, or a more general multistep-multistage method. The resulting convolutional system of boundary integral equations falls in the family of convolution quadratures of Ch. Lubich. In this work our aim is to discuss a new technique for efficiently solving the discrete convolutional system and to present large scale 3D numerical experiments with a wide range of time-discretizations that have up to now not appeared in print. One of the conclusions is that Runge-Kutta methods are often the method of choice even at low accuracy; yet, in connection with hyperbolic problems BDF (backward difference formulas) have been predominant in the literature on convolution quadrature.

  2. Phase Noise-Tolerant Synchronous QPSK/BPSK Baseband-Type Intradyne Receiver Concept With Feedforward Carrier Recovery

    NASA Astrophysics Data System (ADS)

    Noé, Reinhold

    2005-02-01

    Quadrature phase-shift keying (QPSK) is attractive to increase transmission lengths and capacity, especially when it is combined with polarization division multiplex. Baseband processing at the symbol rate allows to keep the required electronic bandwidth low. So far, external cavity lasers seemed to be indispensable for such transmission systems due to linewidth requirements. We propose a feedforward carrier recovery scheme based on regenerative intradyne frequency dividers, i.e., the well-known regenerative frequency divider is extended to process baseband in-phase and quadrature (I and Q) signals. An IF linewidth tolerance of up to 0.001 times the QPSK symbol rate is predicted,2 decades more than for an optical phase locked loop with a realistic loop delay. This means that commercially available DFB lasers shall suffice for synchronous optical QPSK/BPSK transmission.

  3. Accurate and efficient Nyström volume integral equation method for the Maxwell equations for multiple 3-D scatterers

    NASA Astrophysics Data System (ADS)

    Chen, Duan; Cai, Wei; Zinser, Brian; Cho, Min Hyung

    2016-09-01

    In this paper, we develop an accurate and efficient Nyström volume integral equation (VIE) method for the Maxwell equations for a large number of 3-D scatterers. The Cauchy Principal Values that arise from the VIE are computed accurately using a finite size exclusion volume together with explicit correction integrals consisting of removable singularities. Also, the hyper-singular integrals are computed using interpolated quadrature formulae with tensor-product quadrature nodes for cubes, spheres and cylinders, that are frequently encountered in the design of meta-materials. The resulting Nyström VIE method is shown to have high accuracy with a small number of collocation points and demonstrates p-convergence for computing the electromagnetic scattering of these objects. Numerical calculations of multiple scatterers of cubic, spherical, and cylindrical shapes validate the efficiency and accuracy of the proposed method.

  4. New canonic lossy inductor using a single CDBA and its application

    NASA Astrophysics Data System (ADS)

    Pathak, J. K.; Singh, A. K.; Senani, R.

    2016-01-01

    A new lossy inductor (parallel R-L type) using single current differencing buffered amplifier (CDBA) is presented, which employs only two resistors and a grounded capacitor. The proposed lossy inductor is shown to be useful in realizing an oscillator circuit, which provides quadrature voltage outputs using only two CDBAs, three resistors and two grounded capacitors and offers independent control on condition of oscillation and frequency of oscillation up to a frequency of 61 MHz. Detailed non-ideal analysis including single-pole model for voltage and current gain has also been carried out. SPICE simulation results and experimental results based upon the CDBA constructed from commercially available IC AD844 have been included which confirm the practical workability of the proposed lossy inductor and quadrature oscillator circuit.

  5. Saturation-free numerical scheme for computing the flow past a lattice of airfoils and the determination of separation points in a viscous fluid

    NASA Astrophysics Data System (ADS)

    Petrov, A. G.

    2011-07-01

    A numerical method for computing the potential flow past a lattice of airfoils is described. The problem is reduced to a linear integrodifferential equation on the lattice contour, which is then approximated by a linear system of equations with the help of specially derived quadrature formulas. The quadrature formulas exhibit exponential convergence in the number of points on an airfoil and have a simple analytical form. Due to its fast convergence and high accuracy, the method can be used to directly optimize the airfoils as based on any given integral characteristics. The shear stress distribution and the separation points are determined from the velocity distribution at the airfoil boundary calculated by solving the boundary layer equations. The method proposed is free of laborious grid generation procedures and does not involve difficulties associated with numerical viscosity at high Reynolds numbers.

  6. Detection of phase-diffused weak-coherent-states using an optical Costas loop

    NASA Astrophysics Data System (ADS)

    Lopez Leyva, Josue A.; Mondragón, Arturo Arvizu; García, Edith; Mendieta, Francisco J.; Guzman, Eduardo Alvarez; Gallion, Philippe

    2012-10-01

    We describe a homodyne optical Costas loop receiver intended to detect weak coherent states with diffused phase and suppressed carrier phase modulation. In order to get the information contained in the quadrature components of the optical field, we implement an 8-port receiver operating at 1550 nm, based on the manipulation of the state of polarization of both the local oscillator and the data signal. Employing binary phase-shift keying, we make measurements in the time and frequency domain of the quantum noise and bit error rate using an optimum loop filter, and compare the performance of our receiver against the standard quantum limit for the simultaneous quadrature detection, considering both ideal conditions and the overall efficiency of our set up.

  7. Acoustic velocity measurement by means of Laser Doppler Velocimetry: Development of an Extended Kalman Filter and validation in free-field measurement

    NASA Astrophysics Data System (ADS)

    Le Duff, Alain; Plantier, Guy; Valière, Jean C.; Gazengel, Bruno

    2016-03-01

    A signal processing technique, based on the use of an Extended Kalman Filter, has been developed to measure sound fields by means of Laser Doppler Velocimetry in weak flow. This method allows for the parametric estimation of both the acoustic particle and flow velocity for a forced sine-wave excitation where the acoustic frequency is known. The measurements are performed from the in-phase and the quadrature components of the Doppler downshifted signal thanks to an analog quadrature demodulation technique. Then, the estimated performance is illustrated by means of Monte-Carlo simulations obtained from synthesized signals and compared with asymptotic and analytical forms for the Cramer-Rao Bounds. Results allow the validity domain of the method to be defined and show the availability for free-field measurements in a large range. Finally, an application based on real data obtained in free field is presented.

  8. White light-emitting diode based wireless orthogonal frequency division multiplexing link with improved transmission capacity using Bayesian compressive sensing

    NASA Astrophysics Data System (ADS)

    Won, Yong-Yuk; Seo, Dong-Sun; Yoon, Sang Min

    2016-04-01

    We propose a technique that improves the channel capacity of an optical wireless orthogonal frequency division multiplexing (OFDM) transmission, which employs a visible light-emitting diode. An OFDM waveform encoded by quadrature phase shift keying (QPSK) or 16-quadrature amplitude modulation is compressed and then transformed into a sparse waveform using a proposed advanced systematic sampling. At the optical wireless receiver, the original waveform is recovered by L1-minimization based on a Bayesian compressive sensing. Our experimental results show the significant increase in the channel capacity from 31.12 to 51.87 Mbit/s at forward error correction limit (i.e., error vector magnitude of 32%) in case of QPSK symbols.

  9. Advances in Optical Fiber-Based Faraday Rotation Diagnostics

    SciTech Connect

    White, A D; McHale, G B; Goerz, D A

    2009-07-27

    In the past two years, we have used optical fiber-based Faraday Rotation Diagnostics (FRDs) to measure pulsed currents on several dozen capacitively driven and explosively driven pulsed power experiments. We have made simplifications to the necessary hardware for quadrature-encoded polarization analysis, including development of an all-fiber analysis scheme. We have developed a numerical model that is useful for predicting and quantifying deviations from the ideal diagnostic response. We have developed a method of analyzing quadrature-encoded FRD data that is simple to perform and offers numerous advantages over several existing methods. When comparison has been possible, we have seen good agreement with our FRDs and other current sensors.

  10. Unsteady two dimensional airloads acting on oscillating thin airfoils in subsonic ventilated wind tunnels

    NASA Technical Reports Server (NTRS)

    Fromme, J.; Golberg, M.

    1978-01-01

    The numerical calculation of unsteady two dimensional airloads which act upon thin airfoils in subsonic ventilated wind tunnels was studied. Neglecting certain quadrature errors, Bland's collocation method is rigorously proved to converge to the mathematically exact solution of Bland's integral equation, and a three way equivalence was established between collocation, Galerkin's method and least squares whenever the collocation points are chosen to be the nodes of the quadrature rule used for Galerkin's method. A computer program displayed convergence with respect to the number of pressure basis functions employed, and agreement with known special cases was demonstrated. Results are obtained for the combined effects of wind tunnel wall ventilation and wind tunnel depth to airfoil chord ratio, and for acoustic resonance between the airfoil and wind tunnel walls. A boundary condition is proposed for permeable walls through which mass flow rate is proportional to pressure jump.

  11. q -deformed noncommutative cat states and their nonclassical properties

    NASA Astrophysics Data System (ADS)

    Dey, Sanjib

    2015-02-01

    We study several classical-like properties of q -deformed nonlinear coherent states as well as nonclassical behaviors of q -deformed version of the Schrödinger cat states in noncommutative space. Coherent states in q -deformed space are found to be minimum uncertainty states together with the squeezed photon distributions unlike the ordinary systems, where the photon distributions are always Poissonian. Several advantages of utilizing cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the q -deformed parameter has been utilized to improve the squeezing of the quadrature beyond the ordinary case. Most importantly, the parameter provides an extra degree of freedom by which we achieve both quadrature squeezed and number squeezed cat states at the same time in a single system, which is impossible to achieve from ordinary cat states.

  12. Application of TITAN for Simulation of Particle Streaming in a Duct

    NASA Astrophysics Data System (ADS)

    Royston, Katherine; Haghighat, Alireza; Yi, Ce

    2016-02-01

    The TITAN hybrid deterministic transport code is applied to the simulation of particle streaming in a nuclear power plant duct. A simple model is used consisting of a concrete duct emerging from the pressure vessel with an isotropic surface source with a U-235 fission spectrum located at the pressure vessel end. Multiple methods of simulating the duct using the TITAN code are considered to demonstrate the flexibility of the code and the advantages of TITAN's algorithms. These methods include a discrete ordinates (SN) calculation, a characteristics method calculation, and the use of a fictitious quadrature set with simplified ray-tracing. The TITAN code's results are compared with MCNP5 solutions. While all TITAN solutions are obtained in a shorter computation time than the MCNP5 solution, the TITAN solution with the fictitious quadrature set shows the largest speedup.

  13. A fast high-order method to calculate wakefield forces in an electron beam

    SciTech Connect

    Qiang, Ji; Mitchell, Chad; Ryne, Robert D.

    2012-03-22

    In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an O(Nlog(N)) computational cost, where N is the number of grid points. Using the Simpson quadrature rule with an accuracy of O(h4), where h is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force. I. INTRODUCTION

  14. Differentially coherent detection of QASK for frequency-hopping systems. I - Performance in the presence of a Gaussian noise environment

    NASA Technical Reports Server (NTRS)

    Simon, M. K.; Huth, G. K.; Polydoros, A.

    1982-01-01

    Bandwidth-conserving modulation techniques, which trade average power for bandwidth in a favorable exchange, have recently found widespread application in digital radio and satellite communication systems. Quadrature amplitude-shift-keying (QASK) is a particular type of the considered techniques. QASK makes use of multilevel signals to amplitude modulate the in-phase and quadrature components of a carrier. Frequency hopping (FH) is used to protect a conventional communication system from radio frequency interference (RFI) or jamming. Differentially coherent detection provides a possible solution to the effect of phase discontinuities introduced by FH. The application of such a detection technique to QASK signals is discussed. A receiver structure is proposed and its symbol error probability performance for an additive white Gaussian noise (AWGN) background is investigated.

  15. Robust 9-QAM digital recovery for spectrum shaped coherent QPSK signal.

    PubMed

    Huang, Bo; Zhang, Junwen; Yu, Jianjun; Dong, Ze; Li, Xinying; Ou, Haiyan; Chi, Nan; Liu, Wen

    2013-03-25

    We propose 9-ary quadrature amplitude modulation (9-QAM) data recovery for polarization multiplexing-quadrature phase shift keying (PM-QPSK) signal in presence of strong filtering to approach Nyquist bandwidth. The decision-directed least radius distance (DD-LRD) algorithm for blind equalization is used for 9-QAM recovery and intersymbol interference (ISI) compression. It shows the robustness under strong filtering to recover 9-QAM signal rather than QPSK. We demonstrate 112 Gb/s spectrum shaped PM-QPSK signal by wavelength selective switch (WSS) in a 25-GHz channel spacing Nyquist wavelength division multiplexing (NWDM). The final equalized signal is detected by maximum likelihood sequence decision (MLSD) for data bit-error-ratio (BER) measurement. Optical signal-to-noise ratio (OSNR) tolerance is improved by 0.5 dB at a BER of 1x10(-3) compared to constant modulus algorithm (CMA) plus post-filter algorithm.

  16. Transmission of mixed 260-Gb/s PDM-16QAM and 130-Gb/s PDM-QPSK over 960-km and 4160-km dispersion-managed SSMF spans.

    PubMed

    Xie, Chongjin; Raybon, Gregory

    2012-12-10

    We transmit a mix of 260-Gb/s polarization-division-multiplexed 16-ary quadrature-amplitude modulation (PDM-16QAM) and 130-Gb/s polarization-division-multiplexed quadrature-phase-shift-keying (PDM-QPSK) channels at a 50-GHz channel spacing in a dispersion-managed (DM) system with standard single-mode-fiber (SSMF) spans. We study the impact of pulse shaping, time interleaving of polarizations and maximum likelihood (ML) detection techniques on the performance of the system. We show that the pulse shaping and ML detection can increase the transmission distances of the PDM-16QAM channels and PDM-QPSK channels by 50% and 10%, respectively. With 20% overhead hard-decision forward-error-correction (FEC) coding, we successfully transmit the 260-Gb/s PDM-16QAM and 130-Gb/s PDM-QPSK channels over 960-km and 4,160-km, respectively, in the DM system.

  17. Third and fourth virial coefficients for hard disks in narrow channels.

    PubMed

    Mon, K K

    2014-06-28

    The third (B3) and fourth (B4) virial coefficients of hard disks in narrow channels have been evaluated accurately by Gaussian quadrature for a range of channel widths (2Rp), Rp < (√3 + 2)/4 = 0.9930... (in units of the hard disk diameter). These widths correspond to the important regime of fluids in single file formations with only nearest-neighbor interactions. Accurate results are obtained by using N-point Gaussian quadrature and extrapolating to the infinite N limits. Since not much is known about these B3 and B4, our new results should provide guidance for exact calculations of the virial coefficients and benchmarks for other numerical methods. PMID:24985651

  18. Copernicus spectra of beta Lyrae. [in far UV

    NASA Technical Reports Server (NTRS)

    Hack, M.; Hutchings, J. B.; Kondo, Y.; Mccluskey, G. E.; Plavec, M.; Polidan, R. S.

    1974-01-01

    The observations reported were made in August and September 1973. The principal data were scans in the low resolution mode at phases nearly coincident with the two light minima. Shorter scans were obtained at the two quadrature phases. The data show that the secondary component of beta Lyrae is a hotter object than the visible B8 star. The velocity amplitude of the lines suggests that the secondary is the more massive object, by a factor of several times.

  19. Exponential Monte Carlo Convergence on a Homogeneous Right Parallelepiped Using the Reduced Source Method with Legendre Expansion

    SciTech Connect

    Favorite, J.A.

    1999-09-01

    In previous work, exponential convergence of Monte Carlo solutions using the reduced source method with Legendre expansion has been achieved only in one-dimensional rod and slab geometries. In this paper, the method is applied to three-dimensional (right parallelepiped) problems, with resulting evidence suggesting success. As implemented in this paper, the method approximates an angular integral of the flux with a discrete-ordinates numerical quadrature. It is possible that this approximation introduces an inconsistency that must be addressed.

  20. Detecting Eve in communication with continuous-variable Einstein-Podolsky-Rosen correlations

    SciTech Connect

    Messikh, A.

    2007-03-15

    We study the validity of the entanglement parameter introduced in a recent publication by Guangqiang et al. [Phys. Rev. A 73, 012314 (2006)] for detecting Eve, the eavesdropper. We have found that Eve can be detected using this parameter only if Alice establishes a quantum correlation between the Einstein-Podolsky-Rosen (EPR) pair. This quantum correlation is related to the possibility of an apparent violation of the Heisenberg inequality for the quadrature components of the EPR pair.

  1. Method and apparatus for determining shaliness and oil saturations in earth formations using induced polarization in the frequency domain

    SciTech Connect

    Vinegar, H.J.; Waxman, M.H.

    1982-11-16

    An apparatus is disclosed for borehole measurements of the induced polarization of earth formations. The apparatus consists of an induced polarization logger capable of measuring both in-phase and quadrature conductivities in the frequency domain. A method is described which uses these measurements to determine cation exchange capacity per unit pore volume, Qv, brine conductivity, Cw, and oil and water saturations, So and Sw, in shaly sands.

  2. Induced polarization of shaly sands - The effect of clay counterion type

    SciTech Connect

    Vinegar, H.J.; Waxman, M.H.

    1984-01-01

    The effects of clay counterion type on complex conductivities of shaly sands were studied for the Na/sup +/, Li/sup +/, K/sup +/, Ca/sup ++/ and (C/sub 2/H/sub 5/)/sub 4/N/sup +/ ions. The results are treated in terms of the Waxman-Smits in-phase conductivity equation and a new relation describing the quadrature conductivity. Topics considered include polarization, geochemistry, calculation methods, ionic conductivity, and reservoir rock.

  3. A Curved, Elastostatic Boundary Element for Plane Anisotropic Structures

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S.; Klang, Eric C.

    2001-01-01

    The plane-stress equations of linear elasticity are used in conjunction with those of the boundary element method to develop a novel curved, quadratic boundary element applicable to structures composed of anisotropic materials in a state of plane stress or plane strain. The curved boundary element is developed to solve two-dimensional, elastostatic problems of arbitrary shape, connectivity, and material type. As a result of the anisotropy, complex variables are employed in the fundamental solution derivations for a concentrated unit-magnitude force in an infinite elastic anisotropic medium. Once known, the fundamental solutions are evaluated numerically by using the known displacement and traction boundary values in an integral formulation with Gaussian quadrature. All the integral equations of the boundary element method are evaluated using one of two methods: either regular Gaussian quadrature or a combination of regular and logarithmic Gaussian quadrature. The regular Gaussian quadrature is used to evaluate most of the integrals along the boundary, and the combined scheme is employed for integrals that are singular. Individual element contributions are assembled into the global matrices of the standard boundary element method, manipulated to form a system of linear equations, and the resulting system is solved. The interior displacements and stresses are found through a separate set of auxiliary equations that are derived using an Airy-type stress function in terms of complex variables. The capabilities and accuracy of this method are demonstrated for a laminated-composite plate with a central, elliptical cutout that is subjected to uniform tension along one of the straight edges of the plate. Comparison of the boundary element results for this problem with corresponding results from an analytical model show a difference of less than 1%.

  4. Minimizing inter-channel cross-phase modulation with optical phase conjugation in asymmetric fibre links.

    PubMed

    Hesketh, Graham D; Petropoulos, Periklis

    2016-09-01

    Using analytic and numerical modelling of fibre transmission systems that employ optical phase conjugation (OPC), we show inter-channel cross-phase modulation depends on the integrated square error between nonlinear profiles before and after OPC and that arranging amplifiers and tuning power levels is crucial to minimizing noise. We derive modulation transparent formulas for phase noise and optimal power settings. Examples are shown for 16 and 64 quadrature amplitude modulation. PMID:27607633

  5. Generalization of continuous-variable quantum cloning with linear optics

    NASA Astrophysics Data System (ADS)

    Zhai, Zehui; Guo, Juan; Gao, Jiangrui

    2006-05-01

    We propose an asymmetric quantum cloning scheme. Based on the proposal and experiment by Andersen [Phys. Rev. Lett. 94, 240503 (2005)], we generalize it to two asymmetric cases: quantum cloning with asymmetry between output clones and between quadrature variables. These optical implementations also employ linear elements and homodyne detection only. Finally, we also compare the utility of symmetric and asymmetric cloning in an analysis of a squeezed-state quantum key distribution protocol and find that the asymmetric one is more advantageous.

  6. Phase-shifting interferometry based on principal component analysis.

    PubMed

    Vargas, J; Quiroga, J Antonio; Belenguer, T

    2011-04-15

    An asynchronous phase-shifting method based on principal component analysis (PCA) is presented. No restrictions about the background, modulation, and phase shifts are necessary. The presented method is very fast and needs very low computational requirements, so it can be used with very large images and/or very large image sets. The method is based on obtaining two quadrature signals by the PCA algorithm. We have applied the proposed method to simulated and experimental interferograms, obtaining satisfactory results.

  7. High-order integral equations for electromagnetic problems in layered media with applications in biology and solar cells

    NASA Astrophysics Data System (ADS)

    Zinser, Brian

    We present two distinct mathematical models where high-order integral equations are applied to electromagnetic problems. The first problem is to find the electric potential in and around ion channels and Janus particles. The second problem is to find the electromagnetic scattering caused by a set of simple geometric objects. In biology, we consider two types of inhomogeneities: the first one is a simple model of an ion channel which consists of a finite height cylindrical cavity embedded in a layered electrolytes/membrane environment, and the second one is a Janus particle made of two different semi-spherical dielectric materials. A boundary element method (BEM) for the Poisson-Boltzmann equation based on Muller's hyper-singular second kind integral equation formulation is used to accurately compute electrostatic potentials. The proposed BEM gives O(1) condition numbers and we show that the second order basis converges faster and is more accurate than the first order basis. For solar cells, we develop a Nystrom volume integral equation (VIE) method for calculating the electromagnetic scattering according to the Maxwell equations. The Cauchy principal values (CPVs) that arise from the VIE are computed using a finite size exclusion volume with explicit correction integrals. Outside the exclusion, the hyper-singular integrals are computed using an interpolated quadrature formulae with tensor-product quadrature nodes. We considered cubes, rectangles, cylinders, spheres, and ellipsoids. As the new quadrature weights are pre-calculated and tabulated, the integrals are calculated efficiently at runtime. Simulations with many scatterers demonstrate the efficiency of the interpolated quadrature formulae. We also demonstrate that the resulting VIE has high accuracy and p-convergence.

  8. Coherent Communications, Imaging and Targeting

    SciTech Connect

    Stappaerts, E; Baker, K; Gavel, D; Wilks, S; Olivier, S; Brase, J; Olivier, S; Brase, J

    2003-10-03

    Laboratory and field demonstration results obtained as part of the DARPA-sponsored Coherent Communications, Imaging and Targeting (CCIT) program are reviewed. The CCIT concept uses a Phase Conjugation Engine based on a quadrature receiver array, a hologram processor and a spatial light modulator (SLM) for high-speed, digital beam control. Progress on the enabling MEMS SLM, being developed by a consortium consisting of LLNL, academic institutions and small businesses, is presented.

  9. Nonintegrability of density perturbations in the Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Stachowiak, Tomasz; Szydłowski, Marek; Maciejewski, Andrzej J.

    2006-03-01

    We investigate the evolution equation of linear density perturbations in the Friedmann-Robertson-Walker universe with matter, radiation and the cosmological constant. The concept of solvability by quadratures is defined and used to prove that there are no "closed form" solutions except for the known Chernin, Heath, Meszaros and simple degenerate ones. The analysis is performed applying Kovacic's algorithm. The possibility of the existence of other, more general solutions involving special functions is also investigated.

  10. Sampling Downconverter For Radio-Frequency Signals

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.; Rayhrer, B.; Young, L. E.

    1990-01-01

    Phase and delay errors reduced greatly. Proposed GaAs integrated-circuit for receiver of radio signals at gigahertz frequencies samples incoming signal in phase and in quadrature, digitizes it, and down-converts it to baseband in single step. Incorporates both digital and analog components in design offering improved stability, versatility, and sampling bandwidth. Eliminates need for several components found in conventional analog designs, including mixers, postmixer filters, and 90 degree phase shifter.

  11. Monolithic InP receiver chip with a 90° hybrid and 56 GHz balanced photodiodes.

    PubMed

    Runge, Patrick; Schubert, Stefan; Seeger, Angela; Janiak, Klemens; Stephan, Jens; Trommer, Dirk; Domburg, Patrick; Nielsen, Mads Lønstrup

    2012-12-10

    We demonstrate a monolithically integrated quadrature coherent receiver photonic integrated circuit on an InP substrate with a 90° optical hybrid and two balanced 56 GHz pin-photodetectors on chip level and as a packaged device. The presented devices enable the use of 56/64 Gbaud dual polarisation 16-QAM signals either in the C-band or the L-band. PMID:23262859

  12. Spacecraft-to-Earth Communications for Juno and Mars Science Laboratory Critical Events

    NASA Technical Reports Server (NTRS)

    Soriano, Melissa; Finley, Susan; Jongeling, Andre; Fort, David; Goodhart, Charles; Rogstad, David; Navarro, Robert

    2012-01-01

    Deep Space communications typically utilize closed loop receivers and Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK). Critical spacecraft events include orbit insertion and entry, descent, and landing.---Low gain antennas--> low signal -to-noise-ratio.---High dynamics such as parachute deployment or spin --> Doppler shift. During critical events, open loop receivers and Multiple Frequency Shift Keying (MFSK) used. Entry, Descent, Landing (EDL) Data Analysis (EDA) system detects tones in real-time.

  13. Case studies on the development of ScaLAPACK and the NAG numerical PVM library

    SciTech Connect

    Dongarra, J.J. |; Hammarling, S. |; Petitet, A.

    1996-12-31

    In this paper we look at the development of ScaLAPACK, a software library for dense and banded numerical linear algebra, and the NAG Numerical PVM Library, which includes software for dense and sparse linear algebra, quadrature, optimization and random number generation. Both libraries are aimed at distributed memory machines, including networks of workstations. The paper concentrates on the underlying design and the testing of the libraries.

  14. Equivalent Circuit Modeling of Hysteresis Motors

    SciTech Connect

    Nitao, J J; Scharlemann, E T; Kirkendall, B A

    2009-08-31

    We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates, amenable to circuit or digital simulation. 'Hunting' is an oscillatory phenomenon often observed in hysteresis motors. While several works have attempted to model the phenomenon with some partial success, we present a new complete model that predicts hunting from first principles.

  15. Excess-noise-enhanced photon-pair generation in unstable resonators.

    PubMed

    Lamprecht, Claus; Ritsch, Helmut

    2002-05-01

    We investigate a degenerate optical parametric device with a transversely finite unstable cavity configuration operated below threshold. Using an approximate quantum description in terms of a biorthogonal set of effective cavity-matched modes and their adjoint modes, we predict an intracavity field intensity enhancement by the Petermann excess-noise factor, K . This enhancement is accompanied by a reduction of photon bunching and quadrature squeezing. PMID:18007923

  16. FWM-based wavelength conversion of 40 Gbaud PSK signals in a silicon germanium waveguide.

    PubMed

    Ettabib, Mohamed A; Hammani, Kamal; Parmigiani, Francesca; Jones, Liam; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris; Brun, Mickael; Labeye, Pierre; Nicoletti, Sergio; Petropoulos, Periklis

    2013-07-15

    We demonstrate four wave mixing (FWM) based wavelength conversion of 40 Gbaud differential phase shift keyed (DPSK) and quadrature phase shift keyed (QPSK) signals in a 2.5 cm long silicon germanium waveguide. For a 290 mW pump power, bit error ratio (BER) measurements show approximately a 2-dB power penalty in both cases of DPSK (measured at a BER of 10(-9)) and QPSK (at a BER of 10(-3)) signals that we examined.

  17. One-way quantum computing in the optical frequency comb.

    PubMed

    Menicucci, Nicolas C; Flammia, Steven T; Pfister, Olivier

    2008-09-26

    One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO.

  18. Robust and intelligent bearing estimation

    DOEpatents

    Claassen, John P.

    2000-01-01

    A method of bearing estimation comprising quadrature digital filtering of event observations, constructing a plurality of observation matrices each centered on a time-frequency interval, determining for each observation matrix a parameter such as degree of polarization, linearity of particle motion, degree of dyadicy, or signal-to-noise ratio, choosing observation matrices most likely to produce a set of best available bearing estimates, and estimating a bearing for each observation matrix of the chosen set.

  19. Programmable rate modem utilizing digital signal processing techniques

    NASA Technical Reports Server (NTRS)

    Naveh, Arad

    1992-01-01

    The need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) modulation is discussed. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. The design trade-offs in each portion of the modulator and demodulator subsystem are outlined.

  20. Microgravity acoustic mixing for particle cloud combustors

    NASA Technical Reports Server (NTRS)

    Pla, Frederic; Rubinstein, Robert I.

    1990-01-01

    Experimental and theoretical investigations of acoustic mixing procedures designed to uniformly distribute fuel particles in a combustion tube for application in the proposed Particle Cloud Combustion Experiment (PCCE) are described. Two acoustic mixing methods are investigated: mixing in a cylindrical tube using high frequency spinning modes generated by suitably phased, or quadrature speakers, and acoustic premixing in a sphere. Quadrature mixing leads to rapid circumferential circulation of the powder around the tube. Good mixing is observed in the circulating regions. However, because axial inhomogeneities are necessarily present in the acoustic field, this circulation does not extend throughout the tube. Simultaneous operation of the quadrature-speaker set and the axial-speaker was observed to produce considerably enhanced mixing compared to operation of the quadrature-speaker set alone. Mixing experiments using both types of speakers were free of the longitudinal powder drift observed using axial-speakers alone. Vigorous powder mixing was obtained in the sphere for many normal modes: however, in no case was the powder observed to fill the sphere entirely. Theoretical analysis indicated that mixing under steady conditions cannot fill more than a hemisphere except under very unusual conditions. Premixing in a hemisphere may be satisfactory; otherwise, complete mixing in microgravity might be possible by operating the speaker in short bursts. A general conclusion is that acoustic transients are more likely to produce good mixing than steady state conditions. The reason is that in steady conditions, flow structures like nodal planes are possible and often even unavoidable. These tend to separate the mixing region into cells across which powder cannot be transferred. In contrast, transients not only are free of such structures, they also have the characteristics, desirable for mixing, of randomness and disorder. This conclusion is corroborated by mixing

  1. Estimates of the trace of the inverse of a symmetric matrix using the modified Chebyshev algorithm

    NASA Astrophysics Data System (ADS)

    Meurant, Gérard

    2009-07-01

    In this paper we study how to compute an estimate of the trace of the inverse of a symmetric matrix by using Gauss quadrature and the modified Chebyshev algorithm. As auxiliary polynomials we use the shifted Chebyshev polynomials. Since this can be too costly in computer storage for large matrices we also propose to compute the modified moments with a stochastic approach due to Hutchinson (Commun Stat Simul 18:1059-1076, 1989).

  2. TDG - Uncertainty in a design of tuned dry gyro

    NASA Astrophysics Data System (ADS)

    Hayakawa, Yoshiaki; Nibe, Hitoshi

    Measurements were made of the day-to-day stability and temperature coefficient of G-insensitive drift for tuned dry gyros (TDG), in-phase spring rate, quadrature spring rate, and the offset angle consisting of G-insensitive drift. It was found that the governing parameter for instabiity or uncertainty of TDG G-insensitive drift was mainly dependent on the offset angle variation. This conclusion will help to introduce more accuracy in TDG design and fabrication.

  3. Relativistic Three-Nucleon Calculations within the Bethe-Salpeter Approach

    NASA Astrophysics Data System (ADS)

    Bondarenko, S. G.; Burov, V. V.; Yurev, S. A.

    2016-02-01

    The relativistic properties of the three-nucleon system are investigated using the Faddeev equations within the Bethe-Salpeter approach. The nucleon-nucleon interaction is chosen in a separable form. The Gauss quadrature method is used to calculate the integrals. The system of the integral equations is solved by an iterative method. The binding energy and the partial-wave amplitudes (1S0 and 3S1) of the triton are found.

  4. Computational strategies and improvements in the linear algebraic variational approach to rearrangement scattering

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Mladenovic, Mirjana; Zhao, Meishan; Truhlar, Donald G.; Sun, Yan

    1988-01-01

    The computational steps in calculating quantum mechanical reactive scattering amplitudes by the L2 generalized Newton variational principle are discussed with emphasis on computational strategies and recent improvements that make the calculations more efficient. Special emphasis is placed on quadrature techniques, storage management strategies, use of symmetry, and boundary conditions. It is concluded that an efficient implementation of these procedures provides a powerful algorithm for the accurate solution of the Schroedinger equation for rearrangements.

  5. Synchronization techniques for all digital 16-ary QAM receivers operating over land mobile satellite links

    NASA Technical Reports Server (NTRS)

    Fines, P.; Aghvami, A. H.

    1990-01-01

    The performance of a low bit rate (64 Kb/s) all digital 16-ary Differentially Encoded Quadrature Amplitude Modulation (16-DEQAM) demodulator operating over a mobile satellite channel, is considered. The synchronization and detection techniques employed to overcome the Rician channel impairments, are described. The acquisition and steady state performance of this modem, are evaluated by computer simulation over AWGN and RICIAN channels. The results verify the suitability of the 16-DEQAM transmission over slowly faded and/or mildly faded channels.

  6. Discrete mathematical model of wave diffraction on pre-fractal impedance strips. TM mode case

    NASA Astrophysics Data System (ADS)

    Nesvit, K. V.

    2013-10-01

    In this paper a transverse magnetic (TM) wave diffraction problem on pre-fractal impedance strips is considered. The overall aim of this work is to develop a discrete mathematical model of the boundary integral equations (IEs) with the help of special quadrature formulas with the nodes in the zeros of Chebyshev polynomials and to perform a numerical experiments with the help of an efficient discrete singularities method (DSM).

  7. False lock performance in polarity-type Costas receivers in the presence of periodic data patterns

    NASA Astrophysics Data System (ADS)

    Wang, James June-Ming; Lai, Dennis Teng-Tsun; Heng, Veronica Siang-Gek; Godfrey, Robert D.

    The authors address the false-lock performance of receivers which use polarity-type Costas loops for the carrier recovery of unbalanced quadrature phase-shift keyed (QPSK), asynchronous QPSK or binary PSK (BPSK) signals in the presence of periodic data patterns. The potential false-lock frequencies are first identified. Expressions for both true-lock and false-lock components are also derived, thereby allowing numerical evaluation of various key parameters for cases of practical interest.

  8. False lock performance in polarity-type Costas receivers in the presence of periodic data patterns

    NASA Technical Reports Server (NTRS)

    Wang, James June-Ming; Lai, Dennis Teng-Tsun; Heng, Veronica Siang-Gek; Godfrey, Robert D.

    1987-01-01

    The authors address the false-lock performance of receivers which use polarity-type Costas loops for the carrier recovery of unbalanced quadrature phase-shift keyed (QPSK), asynchronous QPSK or binary PSK (BPSK) signals in the presence of periodic data patterns. The potential false-lock frequencies are first identified. Expressions for both true-lock and false-lock components are also derived, thereby allowing numerical evaluation of various key parameters for cases of practical interest.

  9. An approach to optimal guidance of an advanced launch vehicle concept

    NASA Technical Reports Server (NTRS)

    Leung, Martin S.; Calise, Anthony J.

    1990-01-01

    An approximate solution for the maximum payload trajectory of a two-stage launch vehicle using a regular perturbation technique is presented. A zero-order solution for a two-stage vehicle based on a flat-earth approximation and negligible atmospheric effects is obtained in closed form. High-order correction terms are obtained from the solution of nonhomogeneous, first-order linear differential equations by quadrature. This promises the capability for an onboard optimal guidance law implementation.

  10. Stochastic Wireless Channel Modeling, Estimation and Identification from Measurements

    SciTech Connect

    Olama, Mohammed M; Djouadi, Seddik M; Li, Yanyan

    2008-07-01

    This paper is concerned with stochastic modeling of wireless fading channels, parameter estimation, and system identification from measurement data. Wireless channels are represented by stochastic state-space form, whose parameters and state variables are estimated using the expectation maximization algorithm and Kalman filtering, respectively. The latter are carried out solely from received signal measurements. These algorithms estimate the channel inphase and quadrature components and identify the channel parameters recursively. The proposed algorithm is tested using measurement data, and the results are presented.

  11. Multipartite entanglement for continuous variables: A quantum teleportation network

    PubMed

    van Loock P; Braunstein

    2000-04-10

    We show that one single-mode squeezed state distributed among N parties using linear optics suffices to produce a truly N-partite entangled state for any nonzero squeezing and arbitrarily many parties. From this N-partite entangled state, via quadrature measurements of N-2 modes, bipartite entanglement between any two of the N parties can be "distilled," which enables quantum teleportation with an experimentally determinable fidelity better than could be achieved in any classical scheme.

  12. The origin of non-classical effects in a one-dimensional superposition of coherent states

    NASA Technical Reports Server (NTRS)

    Buzek, V.; Knight, P. L.; Barranco, A. Vidiella

    1992-01-01

    We investigate the nature of the quantum fluctuations in a light field created by the superposition of coherent fields. We give a physical explanation (in terms of Wigner functions and phase-space interference) why the 1-D superposition of coherent states in the direction of the x-quadrature leads to the squeezing of fluctuations in the y-direction, and show that such a superposition can generate the squeezed vacuum and squeezed coherent states.

  13. Single-grid spectral collocation for the Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Bernardi, Christine; Canuto, Claudio; Maday, Yvon; Metivet, Brigitte

    1988-01-01

    The aim of the paper is to study a collocation spectral method to approximate the Navier-Stokes equations: only one grid is used, which is built from the nodes of a Gauss-Lobatto quadrature formula, either of Legendre or of Chebyshev type. The convergence is proven for the Stokes problem provided with inhomogeneous Dirichlet conditions, then thoroughly analyzed for the Navier-Stokes equations. The practical implementation algorithm is presented, together with numerical results.

  14. A mathematical model for the doubly-fed wound rotor generator, part 2

    NASA Technical Reports Server (NTRS)

    Brady, F. J.

    1984-01-01

    A mathematical analysis of a doubly-fed wound rotor generator is presented. The constraints of constant stator voltage and frequency to the circuit equations were applied and expressions for the currents and voltages in the machine obtained. The derived variables are redefined as direct and quadrature components. In addition, the apparent (complex) power for both the rotor and the stator are derived in terms of these redefined components.

  15. A mathematical model for the doubly-fed wound rotor generator. II

    NASA Technical Reports Server (NTRS)

    Brady, F. J.

    1986-01-01

    A mathematical analysis of a doubly-fed wound rotor generator is presented. The constraints of constant stator voltage and frequency to the circuit equations were applied and expressions for the currents and voltages in the machine obtained. The derived variables are redefined as direct and quadrature components. In addition, the apparent (complex) power for both the rotor and the stator are derived in terms of these redefined components.

  16. Mixing in the Amazon estuary

    NASA Astrophysics Data System (ADS)

    Bezerra, M. O.

    2010-05-01

    The research area of this work is located at the estuary of the Amazon River (Brazil), near the river mouth. The results of air movement analysis on the surface atmospheric circulation over the Mouth of the Amazonas River, salinity and temperature measures as well as measurements of currents, carried out along a longitudinal section in the navigation canal region of the Northern Bar of the Amazon River (Barra Norte do Rio Amazonas) in June 2006, during the river flood season in the quadrature tide. The dynamics effects affect hydrodynamic,meteorological and hydrographical parameters at the river mouth. The conclusion drawn include that: a) the saline wedge-type stratification can be detected approximately 100km away from the mouth of the Amazon River during the end of the rainy season in the quadrature tide; b) probably, at the Amazon estuary the quadrature entrainment processes are dominant and they are the ones responsible for increased salinity detected in the surface layer, whereas turbulence scattering mixing is not so important. c) The large flow of fresh water from the Amazon River at the end of the rainy season implies the displacement of the saline front position over the internal Amazon continental platform, and d) The tidal wave shows a positive asymmetry in the canal, with floods lasting less than in the ebb tide. This asymmetry decreases towards the ocean, eventually becoming reversed in the presence of a saline wedge. The speeds, however, have a negative asymmetry, with more intense ebb tides, due to the river flow and is more evident by the existence of quadrature tides.

  17. Stationary Boundary Points for a Laplacian Growth Problem in Higher Dimensions

    NASA Astrophysics Data System (ADS)

    Gardiner, Stephen J.; Sjödin, Tomas

    2014-08-01

    It is known that corners of interior angle less than π/2 in the boundary of a plane domain are initially stationary for Hele-Shaw flow arising from an arbitrary injection point inside the domain. This paper establishes the corresponding result for Laplacian growth of domains in higher dimensions. The problem is treated in terms of evolving families of quadrature domains for subharmonic functions.

  18. Reconfigurable orbital angular momentum and polarization manipulation of 100 Gbit/s QPSK data channels.

    PubMed

    Willner, Moshe J; Huang, Hao; Ahmed, Nisar; Xie, Guodong; Ren, Yongxiong; Yan, Yan; Lavery, Martin P J; Padgett, Miles J; Tur, Moshe; Willner, Alan E

    2013-12-15

    We demonstrate reconfigurable orbital angular momentum (OAM) and polarization manipulation of OAM- and polarization-multiplexed 100 Gbit/s quadrature phase shift keying (QPSK) data channels. Each data channel's OAM value and its polarization state can be arbitrarily changed by taking advantage of the unique wavefront profile of OAM beams using liquid crystal on silicon-based spatial light modulators. The manipulation operation introduces a power penalty of <1 dB for 100 Gbit/s QPSK signals.

  19. Comparison of 80 × 112-Gb/s PDM-QPSK system performance over large effective area fiber and standard SMF with Raman amplification.

    PubMed

    Jiang, Xin; Zhu, Benyuan

    2014-05-19

    We experimentally investigate the transmission performance of 80 × 112-Gb/s polarization-division-multiplexed quadrature phase shift keying (PDM-QPSK) signals over large effective area fiber and standard single mode fiber (SSMF) links with Raman amplification. The large effective area fiber offers higher optimum launch power and longer reach than SSMF. The maximum reach of 5200-km is obtained using large effective area fiber. The Gaussian noise (GN) model is explored to fit with experimental data for optimum power.

  20. Monolithic InP receiver chip with a 90° hybrid and 56 GHz balanced photodiodes.

    PubMed

    Runge, Patrick; Schubert, Stefan; Seeger, Angela; Janiak, Klemens; Stephan, Jens; Trommer, Dirk; Domburg, Patrick; Nielsen, Mads Lønstrup

    2012-12-10

    We demonstrate a monolithically integrated quadrature coherent receiver photonic integrated circuit on an InP substrate with a 90° optical hybrid and two balanced 56 GHz pin-photodetectors on chip level and as a packaged device. The presented devices enable the use of 56/64 Gbaud dual polarisation 16-QAM signals either in the C-band or the L-band.

  1. Joint modelling of longitudinal and survival data: incorporating delayed entry and an assessment of model misspecification.

    PubMed

    Crowther, Michael J; Andersson, Therese M-L; Lambert, Paul C; Abrams, Keith R; Humphreys, Keith

    2016-03-30

    A now common goal in medical research is to investigate the inter-relationships between a repeatedly measured biomarker, measured with error, and the time to an event of interest. This form of question can be tackled with a joint longitudinal-survival model, with the most common approach combining a longitudinal mixed effects model with a proportional hazards survival model, where the models are linked through shared random effects. In this article, we look at incorporating delayed entry (left truncation), which has received relatively little attention. The extension to delayed entry requires a second set of numerical integration, beyond that required in a standard joint model. We therefore implement two sets of fully adaptive Gauss-Hermite quadrature with nested Gauss-Kronrod quadrature (to allow time-dependent association structures), conducted simultaneously, to evaluate the likelihood. We evaluate fully adaptive quadrature compared with previously proposed non-adaptive quadrature through a simulation study, showing substantial improvements, both in terms of minimising bias and reducing computation time. We further investigate, through simulation, the consequences of misspecifying the longitudinal trajectory and its impact on estimates of association. Our scenarios showed the current value association structure to be very robust, compared with the rate of change that we found to be highly sensitive showing that assuming a simpler trend when the truth is more complex can lead to substantial bias. With emphasis on flexible parametric approaches, we generalise previous models by proposing the use of polynomials or splines to capture the longitudinal trend and restricted cubic splines to model the baseline log hazard function. The methods are illustrated on a dataset of breast cancer patients, modelling mammographic density jointly with survival, where we show how to incorporate density measurements prior to the at-risk period, to make use of all the available

  2. An Efficient Numerical Approach for Nonlinear Fokker-Planck equations

    NASA Astrophysics Data System (ADS)

    Otten, Dustin; Vedula, Prakash

    2009-03-01

    Fokker-Planck equations which are nonlinear with respect to their probability densities that occur in many nonequilibrium systems relevant to mean field interaction models, plasmas, classical fermions and bosons can be challenging to solve numerically. To address some underlying challenges in obtaining numerical solutions, we propose a quadrature based moment method for efficient and accurate determination of transient (and stationary) solutions of nonlinear Fokker-Planck equations. In this approach the distribution function is represented as a collection of Dirac delta functions with corresponding quadrature weights and locations, that are in turn determined from constraints based on evolution of generalized moments. Properties of the distribution function can be obtained by solution of transport equations for quadrature weights and locations. We will apply this computational approach to study a wide range of problems, including the Desai-Zwanzig Model (for nonlinear muscular contraction) and multivariate nonlinear Fokker-Planck equations describing classical fermions and bosons, and will also demonstrate good agreement with results obtained from Monte Carlo and other standard numerical methods.

  3. On point estimation of the abnormality of a Mahalanobis index

    PubMed Central

    Elfadaly, Fadlalla G.; Garthwaite, Paul H.; Crawford, John R.

    2016-01-01

    Mahalanobis distance may be used as a measure of the disparity between an individual’s profile of scores and the average profile of a population of controls. The degree to which the individual’s profile is unusual can then be equated to the proportion of the population who would have a larger Mahalanobis distance than the individual. Several estimators of this proportion are examined. These include plug-in maximum likelihood estimators, medians, the posterior mean from a Bayesian probability matching prior, an estimator derived from a Taylor expansion, and two forms of polynomial approximation, one based on Bernstein polynomial and one on a quadrature method. Simulations show that some estimators, including the commonly-used plug-in maximum likelihood estimators, can have substantial bias for small or moderate sample sizes. The polynomial approximations yield estimators that have low bias, with the quadrature method marginally to be preferred over Bernstein polynomials. However, the polynomial estimators sometimes yield infeasible estimates that are outside the 0–1 range. While none of the estimators are perfectly unbiased, the median estimators match their definition; in simulations their estimates of the proportion have a median error close to zero. The standard median estimator can give unrealistically small estimates (including 0) and an adjustment is proposed that ensures estimates are always credible. This latter estimator has much to recommend it when unbiasedness is not of paramount importance, while the quadrature method is recommended when bias is the dominant issue. PMID:27375307

  4. Simplified signal processing for impedance spectroscopy with spectrally sparse sequences

    NASA Astrophysics Data System (ADS)

    Annus, P.; Land, R.; Reidla, M.; Ojarand, J.; Mughal, Y.; Min, M.

    2013-04-01

    Classical method for measurement of the electrical bio-impedance involves excitation with sinusoidal waveform. Sinusoidal excitation at fixed frequency points enables wide variety of signal processing options, most general of them being Fourier transform. Multiplication with two quadrature waveforms at desired frequency could be easily accomplished both in analogue and in digital domains, even simplest quadrature square waves can be considered, which reduces signal processing task in analogue domain to synchronous switching followed by low pass filter, and in digital domain requires only additions. So called spectrally sparse excitation sequences (SSS), which have been recently introduced into bio-impedance measurement domain, are very reasonable choice when simultaneous multifrequency excitation is required. They have many good properties, such as ease of generation and good crest factor compared to similar multisinusoids. Typically, the usage of discrete or fast Fourier transform in signal processing step is considered so far. Usage of simplified methods nevertheless would reduce computational burden, and enable simpler, less costly and less energy hungry signal processing platforms. Accuracy of the measurement with SSS excitation when using different waveforms for quadrature demodulation will be compared in order to evaluate the feasibility of the simplified signal processing. Sigma delta modulated sinusoid (binary signal) is considered to be a good alternative for a synchronous demodulation.

  5. Wide band low phase noise QVCO based on superharmonic injection locking

    NASA Astrophysics Data System (ADS)

    Yalan, Xu; Jinguang, Jiang; Jianghua, Liu

    2016-01-01

    A wide band, injection-coupled LC quadrature voltage control oscillator is presented. In the proposed circuit, two oscillators are injection locked by coupling their second-order harmonics in anti-phase, forcing the outputs of two oscillators into a quadrature phase state. As the common-mode point sampling the second harmonic frequency, flicker noise of the tail current is suppressed, the phase noise is reduced. The proposed design accomplishes a wide tuning frequency range by a combination of using a 5-bit switch capacitor array (SCA) for discrete tuning in addition to linearly varying AMOS varactors for continuous tuning. The proposed design has been fabricated and verified in a 0.18 μm TSMC CMOS technology process. The measurement indicates that the quadrature voltage controlled oscillator has a 41.7% tuning range from 3.53 to 5.39 GHz. The measured phase noise is 127.98 dBc/Hz at 1 MHz offset at a 1.8 V supply voltage with a power consumption of 12 mW at a carrier frequency of 4.85 GHz. Project supporteded by the National Natural Science Foundation of China (No. 41274047) and the Guangdong Province Science and Technology Program (No. 2013B090500049).

  6. Parallel-Processing Equalizers for Multi-Gbps Communications

    NASA Technical Reports Server (NTRS)

    Gray, Andrew; Ghuman, Parminder; Hoy, Scott; Satorius, Edgar H.

    2004-01-01

    Architectures have been proposed for the design of frequency-domain least-mean-square complex equalizers that would be integral parts of parallel- processing digital receivers of multi-gigahertz radio signals and other quadrature-phase-shift-keying (QPSK) or 16-quadrature-amplitude-modulation (16-QAM) of data signals at rates of multiple gigabits per second. Equalizers as used here denotes receiver subsystems that compensate for distortions in the phase and frequency responses of the broad-band radio-frequency channels typically used to convey such signals. The proposed architectures are suitable for realization in very-large-scale integrated (VLSI) circuitry and, in particular, complementary metal oxide semiconductor (CMOS) application- specific integrated circuits (ASICs) operating at frequencies lower than modulation symbol rates. A digital receiver of the type to which the proposed architecture applies (see Figure 1) would include an analog-to-digital converter (A/D) operating at a rate, fs, of 4 samples per symbol period. To obtain the high speed necessary for sampling, the A/D and a 1:16 demultiplexer immediately following it would be constructed as GaAs integrated circuits. The parallel-processing circuitry downstream of the demultiplexer, including a demodulator followed by an equalizer, would operate at a rate of only fs/16 (in other words, at 1/4 of the symbol rate). The output from the equalizer would be four parallel streams of in-phase (I) and quadrature (Q) samples.

  7. Compensation of spectral and RF errors in swept-source OCT for high extinction complex demodulation.

    PubMed

    Siddiqui, Meena; Tozburun, Serhat; Zhang, Ellen Ziyi; Vakoc, Benjamin J

    2015-03-01

    We provide a framework for compensating errors within passive optical quadrature demodulation circuits used in swept-source optical coherence tomography (OCT). Quadrature demodulation allows for detection of both the real and imaginary components of an interference fringe, and this information separates signals from positive and negative depth spaces. To achieve a high extinction (∼60 dB) between these positive and negative signals, the demodulation error must be less than 0.1% in amplitude and phase. It is difficult to construct a system that achieves this low error across the wide spectral and RF bandwidths of high-speed swept-source systems. In a prior work, post-processing methods for removing residual spectral errors were described. Here, we identify the importance of a second class of errors originating in the RF domain, and present a comprehensive framework for compensating both spectral and RF errors. Using this framework, extinctions >60 dB are demonstrated. A stability analysis shows that calibration parameters associated with RF errors are accurate for many days, while those associated with spectral errors must be updated prior to each imaging session. Empirical procedures to derive both RF and spectral calibration parameters simultaneously and to update spectral calibration parameters are presented. These algorithms provide the basis for using passive optical quadrature demodulation circuits with high speed and wide-bandwidth swept-source OCT systems.

  8. A Slow Streamer Blowout at the Sun and Ulysses

    NASA Technical Reports Server (NTRS)

    Seuss, S. T.; Bemporad, A.; Poletto, G.

    2004-01-01

    On 10 June 2000 a streamer on the southeast limb slowly disappeared from LASCO/C2 over approximately 10 hours. A small CME was reported in C2. A substantial interplanetary CME (ICME) was later detected at Ulysses, which was at quadrature with the Sun and SOHO at the time. This detection illustrates the properties of an ICME for a known solar source and demonstrates that the identification can be done even beyond 3 AU. Slow streamer blowouts such as this have long been known but are little studied. We report on the SOHO observation of a coronal mass ejection (CME) on the solar limb and the subsequent in situ detection at Ulysses, which was near quadrature at the time, above the location of the CME. SOHO-Ulysses quadrature was 13 June, when Ulysses was 3.36 AU from the Sun and 58.2 degrees south of the equator off the east limb. The slow streamer blowout was on 10 June, when the SOHO-Sun-Ulysses angle was 87 degrees.

  9. Short and independent characteristic methods for discrete ordinates radiation transport with two-dimensional and three-dimensional regular Cartesian meshes

    NASA Astrophysics Data System (ADS)

    Suriano, Mark Allen

    2001-07-01

    Accurate, reliable, and robust discrete neutral particle radiation transport codes are needed in order to perform realistic 3D engineering calculations. Current neutron transport codes use low order spatial quadratures that are inaccurate unless a highly refined spatial mesh is used. In this work various higher order characteristic spatial quadratures are derived, implemented, and tested. Regular meshes of rectangular (2D) and of rectangular parallelepiped (boxoid) cells are supported. Short characteristic (linear characteristic [LC] and exponential characteristic [EC]) methods are compared with the corresponding independent characteristic (ILC and IEC) methods. The latter readily provide for plane parallel implementation. All transport results were benchmarked against Monte Carlo calculations. The diamond difference (DD) method was also tested and compared to the characteristic spatial quadratures. IEC and EC were found to be robust, reliable, and accurate for thin, intermediate, and optically thick cells. LC was robust, reliable, and accurate for cells of thin to intermediate (approximately 2 mean free paths) optical thickness. ILC was not pursued in 3D due to its anticipated excessive computational cost. DD was unreliable (as expected) over the range of test problems. We conclude that IEC and EC are apt methods for a wide range of problems, and provide the ability to perform realistic engineering calculations on coarse cells given nonnegative group-to-group, ordinate-to-ordinate cross section data.

  10. Why are the P{sub n} and S{sub n} Methods Equivalent

    SciTech Connect

    Cullen, D E

    2001-09-19

    The author assumes that the reader is familiar with the Spherical harmonics, Pn, method and the discrete ordinates, S{sub n}, method; for a derivation of the equations used in these methods. I will only discuss the Boltzmann equation in one dimension, and the Sn method using Gaussian quadrature. I will do this merely to simplify the following discussion; once you understand the concepts presented here you can easily extend the conclusions to more general situations. Why are the spherical harmonics P{sub n} and discrete ordinate S{sub n} methods, or more correctly the P{sub n} and S{sub n+1} methods, equivalent, e.g., P{sub 3} is equivalent to S{sub 4}? When the S{sub n} method uses a Gaussian quadrature most textbooks will tell you that both methods are equivalent to assuming that the angular flux can be represented by a Legendre polynomial expansion of order n. Most textbooks are wrong [1]. We know that the S{sub n} method constrains the ''particles'' to travel in discrete directions; when Gaussian quadrature is used these discrete directions correspond to the zeros of the Legendre polynomial P{sub n+1}({mu}). What is not immediately obvious is that the P{sub n} method constrains the ''particles'' in exactly the same way. That is why the two methods are equivalent. The author discusses this in terms of physics and mathematics.

  11. Mathematical and Computational Tools for Predictive Simulation of Complex Coupled Systems under Uncertainty

    SciTech Connect

    Ghanem, Roger

    2013-03-25

    Methods and algorithms are developed to enable the accurate analysis of problems that exhibit interacting physical processes with uncertainties. These uncertainties can pertain either to each of the physical processes or to the manner in which they depend on each others. These problems are cast within a polynomial chaos framework and their solution then involves either solving a large system of algebraic equations or a high dimensional numerical quadrature. In both cases, the curse of dimensionality is manifested. Procedures are developed for the efficient evaluation of the resulting linear equations that advantage of the block sparse structure of these equations, resulting in a block recursive Schur complement construction. In addition, embedded quadratures are constructed that permit the evaluation of very high-dimensional integrals using low-dimensional quadratures adapted to particular quantities of interest. The low-dimensional integration is carried out in a transformed measure space in which the quantity of interest is low-dimensional. Finally, a procedure is also developed to discover a low-dimensional manifold, embedded in the initial high-dimensional one, in which scalar quantities of interest exist. This approach permits the functional expression of the reduced space in terms of the original space, thus permitting cross-scale sensitivity analysis.

  12. Compensation of spectral and RF errors in swept-source OCT for high extinction complex demodulation

    PubMed Central

    Siddiqui, Meena; Tozburun, Serhat; Zhang, Ellen Ziyi; Vakoc, Benjamin J.

    2015-01-01

    We provide a framework for compensating errors within passive optical quadrature demodulation circuits used in swept-source optical coherence tomography (OCT). Quadrature demodulation allows for detection of both the real and imaginary components of an interference fringe, and this information separates signals from positive and negative depth spaces. To achieve a high extinction (∼60 dB) between these positive and negative signals, the demodulation error must be less than 0.1% in amplitude and phase. It is difficult to construct a system that achieves this low error across the wide spectral and RF bandwidths of high-speed swept-source systems. In a prior work, post-processing methods for removing residual spectral errors were described. Here, we identify the importance of a second class of errors originating in the RF domain, and present a comprehensive framework for compensating both spectral and RF errors. Using this framework, extinctions >60 dB are demonstrated. A stability analysis shows that calibration parameters associated with RF errors are accurate for many days, while those associated with spectral errors must be updated prior to each imaging session. Empirical procedures to derive both RF and spectral calibration parameters simultaneously and to update spectral calibration parameters are presented. These algorithms provide the basis for using passive optical quadrature demodulation circuits with high speed and wide-bandwidth swept-source OCT systems. PMID:25836784

  13. P-code enhanced method for processing encrypted GPS signals without knowledge of the encryption code

    NASA Technical Reports Server (NTRS)

    Meehan, Thomas K. (Inventor); Thomas, Jr., Jess Brooks (Inventor); Young, Lawrence E. (Inventor)

    2000-01-01

    In the preferred embodiment, an encrypted GPS signal is down-converted from RF to baseband to generate two quadrature components for each RF signal (L1 and L2). Separately and independently for each RF signal and each quadrature component, the four down-converted signals are counter-rotated with a respective model phase, correlated with a respective model P code, and then successively summed and dumped over presum intervals substantially coincident with chips of the respective encryption code. Without knowledge of the encryption-code signs, the effect of encryption-code sign flips is then substantially reduced by selected combinations of the resulting presums between associated quadrature components for each RF signal, separately and independently for the L1 and L2 signals. The resulting combined presums are then summed and dumped over longer intervals and further processed to extract amplitude, phase and delay for each RF signal. Precision of the resulting phase and delay values is approximately four times better than that obtained from straight cross-correlation of L1 and L2. This improved method provides the following options: separate and independent tracking of the L1-Y and L2-Y channels; separate and independent measurement of amplitude, phase and delay L1-Y channel; and removal of the half-cycle ambiguity in L1-Y and L2-Y carrier phase.

  14. Analog filtering of large solvent signals for improved dynamic range in high-resolution NMR.

    PubMed

    Redfield, A G; Kunz, S D

    1998-01-01

    The large solvent signal from samples in H2O solvent still challenges the dynamic range capability of any spectrometer. The solvent signal can be largely removed with a pair of simple resistor-capacitor (RC) high-pass filters when the solvent frequency is set at center band (zero frequency) using quadrature detection, with RC approximately 0.5 ms. However, an approximately 0.5-ms transient remains at initial time, which we reduce fourfold for a short time only, just before the A/D converter, by means of a variable-gain amplifier, and later restore with software. This modification can result in a nearly fourfold increase in dynamic range. When we converted to a frequency-shifted mode (A. G. Redfield and S. D. Kunz, 1994, J. Magn. Reson. A 108, 234-237) we replaced the RC high-pass filter with a quadrature feedback notch filter tuned to the solvent frequency (5.06 kHz). This filter is an example of a class of two-input/two-output filters which maintain the spectral integrity (image-free character) of quadrature signals. Digital filters of the same type are also considered briefly. We discuss the implications of these ideas for spectrometer input design, including schemes for elimination of radiation damping, and effects of probe bandwidth on extreme oversampling. PMID:9469905

  15. RF System Modeling for the CEBAF Energy Upgrade

    SciTech Connect

    Tomasz Plawski, J. Hovater

    2009-05-01

    An RF system model, based on MATLAB/SIMULINK, has been developed for analyzing the basic characteristics of the low level RF (LLRF) control system being designed for the CEBAF 12 GeV Energy Upgrade. In our model, a typical passband cavity representation is simplified to in-phase and quadrature (I&Q) components. Lorentz Force and microphonic detuning are incorporated as a new quadrature carrier frequency (frequency modulation). Beam is also represented as in-phase and quadrature components and superpositioned with the cavity field vector. Signals pass through two low pass filters, where the cutoff frequency is equal to half of the cavity bandwidth, then they are demodulated using the same detuning frequency. Because only baseband I&Q signals are calculated, the simulation process is very fast when compared to other controller-cavity models. During the design process we successfully analyzed gain requirements vs. field stability for different superconducting cavity microphonic backgrounds and Lorentz Force coefficients. Moreover, we were able to evaluate different types of a LLRF system’s control algorithm: GDR (Generator Driven Resonator) and SEL (Self Excited Loop) [1] as well as klystron power requirements for different cavities and beam loads.

  16. An optimal scheme for numerical evaluation of Eshelby tensors and its implementation in a MATLAB package for simulating the motion of viscous ellipsoids in slow flows

    NASA Astrophysics Data System (ADS)

    Qu, Mengmeng; Jiang, Dazhi; Lu, Lucy X.

    2016-11-01

    To address the multiscale deformation and fabric development in Earth's ductile lithosphere, micromechanics-based self-consistent homogenization is commonly used to obtain macroscale rheological properties from properties of constituent elements. The homogenization is heavily based on the solution of an Eshelby viscous inclusion in a linear viscous medium and the extension of the solution to nonlinear viscous materials. The homogenization requires repeated numerical evaluation of Eshelby tensors for constituent elements and becomes ever more computationally challenging as the elements are deformed to more elongate or flattened shapes. In this paper, we develop an optimal scheme for evaluating Eshelby tensors, using a combination of a product Gaussian quadrature and the Lebedev quadrature. We first establish, through numerical experiments, an empirical relationship between the inclusion shape and the computational time it takes to evaluate its Eshelby tensors. We then use the relationship to develop an optimal scheme for selecting the most efficient quadrature to obtain the Eshelby tensors. The optimal scheme is applicable to general homogenizations. In this paper, it is implemented in a MATLAB package for investigating the evolution of solitary rigid or deformable inclusions and the development of shape preferred orientations in multi-inclusion systems during deformation. The MATLAB package, upgrading an earlier effort written in MathCad, can be downloaded online.

  17. Whole-procedure clinical accuracy of Gamma Knife treatments of large lesions

    SciTech Connect

    Ma Lijun; Chuang, Cynthia; Descovich, Martina; Petti, Paula; Smith, Vernon; Verhey, Lynn

    2008-11-15

    The mechanical accuracy of Gamma Knife radiosurgery based on single-isocenter measurement has been established to within 0.3 mm. However, the full delivery accuracy for Gamma Knife treatments of large lesions has only been estimated via the quadrature-sum analysis. In this study, the authors directly measured the whole-procedure accuracy for Gamma Knife treatments of large lesions to examine the validity of such estimation. The measurements were conducted on a head-phantom simulating the whole treatment procedure that included frame placement, computed tomography imaging, treatment planning, and treatment delivery. The results of the measurements were compared with the dose calculations from the treatment planning system. Average agreements of 0.1-1.6 mm for the isodose lines ranging from 25% to 90% of the maximum dose were found despite potentially large contributing uncertainties such as 3-mm imaging resolution, 2-mm dose grid size, 1-mm frame registration, multi-isocenter deliveries, etc. The results of our measurements were found to be significantly smaller (>50%) than the calculated value based on the quadrature-sum analysis. In conclusion, Gamma Knife treatments of large lesions can be delivered much more accurately than predicted from the quadrature-sum analysis of major sources of uncertainties from each step of the delivery chain.

  18. Fast simulation of Gaussian-mode scattering for precision interferometry

    NASA Astrophysics Data System (ADS)

    Brown, D.; Smith, R. J. E.; Freise, A.

    2016-02-01

    Understanding how laser light scatters from realistic mirror surfaces is crucial for the design, commissioning and operation of precision interferometers, such as the current and next generation of gravitational-wave detectors. Numerical simulations are indispensable tools for this task but their utility can in practice be limited by the computational cost of describing the scattering process. In this paper we present an efficient method to significantly reduce the computational cost of optical simulations that incorporate scattering. This is accomplished by constructing a near optimal representation of the complex, multi-parameter 2D overlap integrals that describe the scattering process (referred to as a reduced order quadrature). We demonstrate our technique by simulating a near-unstable Fabry-Perot cavity and its control signals using similar optics to those installed in one of the LIGO gravitational-wave detectors. We show that using reduced order quadrature reduces the computational time of the numerical simulation from days to minutes (a speed-up of ≈ 2750× ) while incurring negligible errors. This significantly increases the feasibility of modelling interferometers with realistic imperfections to overcome current limits in state-of-the-art optical systems. While we focus on the Hermite-Gaussian basis for describing the scattering of the optical fields, our method is generic and could be applied with any suitable basis. An implementation of this reduced order quadrature method is provided in the open source interferometer simulation software Finesse.

  19. Force to rebalance control of HRG and suppression of its errors on the basis of FPGA.

    PubMed

    Wang, Xu; Wu, Wenqi; Luo, Bing; Fang, Zhen; Li, Yun; Jiang, Qingan

    2011-01-01

    A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability.

  20. Analog filtering of large solvent signals for improved dynamic range in high-resolution NMR.

    PubMed

    Redfield, A G; Kunz, S D

    1998-01-01

    The large solvent signal from samples in H2O solvent still challenges the dynamic range capability of any spectrometer. The solvent signal can be largely removed with a pair of simple resistor-capacitor (RC) high-pass filters when the solvent frequency is set at center band (zero frequency) using quadrature detection, with RC approximately 0.5 ms. However, an approximately 0.5-ms transient remains at initial time, which we reduce fourfold for a short time only, just before the A/D converter, by means of a variable-gain amplifier, and later restore with software. This modification can result in a nearly fourfold increase in dynamic range. When we converted to a frequency-shifted mode (A. G. Redfield and S. D. Kunz, 1994, J. Magn. Reson. A 108, 234-237) we replaced the RC high-pass filter with a quadrature feedback notch filter tuned to the solvent frequency (5.06 kHz). This filter is an example of a class of two-input/two-output filters which maintain the spectral integrity (image-free character) of quadrature signals. Digital filters of the same type are also considered briefly. We discuss the implications of these ideas for spectrometer input design, including schemes for elimination of radiation damping, and effects of probe bandwidth on extreme oversampling.

  1. A New Representative for Small-Body Gravity Estimation

    NASA Technical Reports Server (NTRS)

    Jones, Brandon A.; Beylkin, Gregory; Born, George H.; Provence, Robert S.

    2010-01-01

    One of the options proposed in the 2009 Review of the U. S. Human Spaceflight Plans Committee calls for the consideration of robotic and human missions to asteroids. Beginning in 2000, the NEAR Shoemaker spacecraft inserted into orbit about the asteroid 433 Eros, and studied it for a year before landing. The Hayabusa satellite journeyed to 25143 Itokawa, and operated in a proximity of the asteroid for several months before landing to collect a return sample. Additionally, the DAWN satellite, which was launched in 2007, will explore the dwarf-planet Ceres and the asteroid 4 Vesta in the next three years. These are just several examples of current interests in exploring asteroids. In this paper, we explore an alternative for estimating the gravity field of a small body using observations of an orbiting satellite. Our approach uses two new mathematical tools, the quadratures (on a sphere) invariant under the icosahedral group, and a multiresolution representation of the gravity potential. With the near optimal quadratures on the sphere, we minimize the number of parameters needed to recover a function. Also, instead of estimating the coefficients of the spherical harmonics, the new quadratures allow us to estimate directly the values of the gravity field since they offer an analogue of the Lagrange-type interpolation.

  2. Force to Rebalance Control of HRG and Suppression of Its Errors on the Basis of FPGA

    PubMed Central

    Wang, Xu; Wu, Wenqi; Luo, Bing; Fang, Zhen; Li, Yun; Jiang, Qingan

    2011-01-01

    A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability. PMID:22247692

  3. Lord-Wingersky Algorithm Version 2.0 for Hierarchical Item Factor Models with Applications in Test Scoring, Scale Alignment, and Model Fit Testing

    PubMed Central

    Cai, Li

    2014-01-01

    Lord and Wingersky’s (1984) recursive algorithm for creating summed score based likelihoods and posteriors has a proven track record in unidimensional item response theory (IRT) applications. Extending the recursive algorithm to handle multidimensionality is relatively simple, especially with fixed quadrature because the recursions can be defined on a grid formed by direct products of quadrature points. However, the increase in computational burden remains exponential in the number of dimensions, making the implementation of the recursive algorithm cumbersome for truly high dimensional models. In this paper, a dimension reduction method that is specific to the Lord-Wingersky recursions is developed. This method can take advantage of the restrictions implied by hierarchical item factor models, e.g., the bifactor model, the testlet model, or the two-tier model, such that a version of the Lord-Wingersky recursive algorithm can operate on a dramatically reduced set of quadrature points. For instance, in a bifactor model, the dimension of integration is always equal to 2, regardless of the number of factors. The new algorithm not only provides an effective mechanism to produce summed score to IRT scaled score translation tables properly adjusted for residual dependence, but leads to new applications in test scoring, linking, and model fit checking as well. Simulated and empirical examples are used to illustrate the new applications. PMID:25233839

  4. Lord-Wingersky Algorithm Version 2.0 for Hierarchical Item Factor Models with Applications in Test Scoring, Scale Alignment, and Model Fit Testing.

    PubMed

    Cai, Li

    2015-06-01

    Lord and Wingersky's (Appl Psychol Meas 8:453-461, 1984) recursive algorithm for creating summed score based likelihoods and posteriors has a proven track record in unidimensional item response theory (IRT) applications. Extending the recursive algorithm to handle multidimensionality is relatively simple, especially with fixed quadrature because the recursions can be defined on a grid formed by direct products of quadrature points. However, the increase in computational burden remains exponential in the number of dimensions, making the implementation of the recursive algorithm cumbersome for truly high-dimensional models. In this paper, a dimension reduction method that is specific to the Lord-Wingersky recursions is developed. This method can take advantage of the restrictions implied by hierarchical item factor models, e.g., the bifactor model, the testlet model, or the two-tier model, such that a version of the Lord-Wingersky recursive algorithm can operate on a dramatically reduced set of quadrature points. For instance, in a bifactor model, the dimension of integration is always equal to 2, regardless of the number of factors. The new algorithm not only provides an effective mechanism to produce summed score to IRT scaled score translation tables properly adjusted for residual dependence, but leads to new applications in test scoring, linking, and model fit checking as well. Simulated and empirical examples are used to illustrate the new applications.

  5. Quantum security in homodyne reception using weak coherent states

    NASA Astrophysics Data System (ADS)

    García, E.; López, J. A.; Mendieta, F. J.; Arvizu, A.

    2011-09-01

    We present an experimental 8-port Balanced Homodyne Detector at 1550 nm wavelength, operating in free space, implemented with polarization devices to produce a circularly polarized local oscillator, splitting its In-Phase and Quadrature components to beat separately with the weak coherent incoming signal. This allows the simultaneous measurements of the 2 quadratures at the price of an additional noise due to the vacuum fields that leak via the unused ports, resulting in a modified Husimi function for joint probability distribution for the quadrature components. These schemes require the proper optical phase synchronization between the local oscillator and the incoming field, which constitutes a challenge for weak coherent state reception. To achieve this we designed and implemented an optical Costas loop; the feedback loop (especially the loop filter) which is a result of the optimal design has an impact on the mutual information between transmitter and receiver, being this parameter a condition to generate the cryptographic key. We present experimental and theoretical results on the performance of the mutual information between the transmitter and the receiver due the phase error for different photon numbers.

  6. Semiconductor converters/inverters for photovoltaic power supply

    NASA Astrophysics Data System (ADS)

    Longrigg, P.

    The two generic types of DC to AC inverters are discussed, considering inherent problems and prospects for solution. A current source converter uses reference current from the AC utility line to chop the DC into AC using four thyristors as switches. Difficulties exist in that DC current contains lagging quadrature currents and are harmonics rich. Solutions are indicated in the form of tuned filters for controlling harmonics and a static VAR generator for the quadrature demand, except that solving the quadrature problem reintroduces further harmonics. In the voltage-sourced converter, which performs much like a synchronous generator, harmonics are also present and can be eliminated with pulse-width modulation. However, at lower powers, switching accelerates beyond attainable switching speed levels. Finally, a current-fed, force commutated converter is described which commutates ahead of the AC voltage; it may need special filters or buffers in addition to harmonics filters. Further studies are recommended in areas of cost reductions, interface overvoltage protection, harmonics, source stability, safety and code requirements, and utility system protection, all pertinent to photovoltaic power conditioning. Circuitry diagrams and AC V-I graphs are provided.

  7. Initial post-buckling of variable-stiffness curved panels

    NASA Astrophysics Data System (ADS)

    White, S. C.; Raju, G.; Weaver, P. M.

    2014-11-01

    Variable-stiffness shells are curved composite structures in which the fibre-reinforcement follow curvilinear paths in space. Having a wider design space than traditional composite shells, they have the potential to improve a wide variety of weight-critical structures. In this paper, a new method for computing the initial post-buckling response of variable-stiffness cylindrical panels is presented, based on the differential quadrature method. Integro-differential governing and boundary equations governing the problem, derived with Koiter's theory (Koiter, 1945), are solved using a mixed generalised differential quadrature (GDQ) and integral quadrature (GIQ) approach. The post-buckling behaviour is determined on the basis of a quadratic expansion of the displacement fields. Orthogonality of the mode-shapes in the expansion series is ensured by a novel use of the Moore-Penrose generalised matrix inverse for solving the GDQ-GIQ equations. The new formulation is validated against benchmark analytical post-buckling results for constant stiffness plates and shells, and compared with non-linear finite-element (FE) analysis for variable-stiffness shells. Stability estimates are found to be in good agreement with incremental FE results in the vicinity of the buckling load, requiring only a fraction of the number of variables used by the current method.

  8. Optical 8QAM and 8PSK synthesis by cascading arbitrary 2QAM with squared QPSK.

    PubMed

    Lu, Guo-Wei; Mendinueta, José Manuel Delgado; Sakamoto, Takahide; Wada, Naoya; Kawanishi, Tetsuya

    2015-08-10

    In dynamic optical networking scenarios, it is desirable that the optical transmitter chooses the most suitable modulation format in order to achieve optimal transmission performance. Owing to the ability of switching among different modulation formats, flexible optical transmitters based on reconfigurable optical devices are becoming a key component for the implementation of future flexible optical networks. In this paper, we experimentally demonstrate a flexible 8-ary transmitter to achieve adaptive switching between 8-ary phase-shift keying (8PSK) and circular 8-ary quadrature-amplitude modulation (8QAM) through reconfiguration of two cascaded in-phase/quadrature (IQ) modulators with different driving signals and biasing conditions. An arbitrary binary quadrature-amplitude modulation (2QAM) with constant or non-constant amplitude is proposed and experimentally demonstrated using an IQ modulator. Then, optical 8PSK or 8QAM modulation formats are successfully synthesized when a standard squared QPSK modulator is cascaded with a constant-amplitude or non-constant-amplitude 2QAM, respectively.

  9. On the consistency between nearest-neighbor peridynamic discretizations and discretized classical elasticity models

    DOE PAGES

    Seleson, Pablo; Du, Qiang; Parks, Michael L.

    2016-08-16

    The peridynamic theory of solid mechanics is a nonlocal reformulation of the classical continuum mechanics theory. At the continuum level, it has been demonstrated that classical (local) elasticity is a special case of peridynamics. Such a connection between these theories has not been extensively explored at the discrete level. This paper investigates the consistency between nearest-neighbor discretizations of linear elastic peridynamic models and finite difference discretizations of the Navier–Cauchy equation of classical elasticity. While nearest-neighbor discretizations in peridynamics have been numerically observed to present grid-dependent crack paths or spurious microcracks, this paper focuses on a different, analytical aspect of suchmore » discretizations. We demonstrate that, even in the absence of cracks, such discretizations may be problematic unless a proper selection of weights is used. Specifically, we demonstrate that using the standard meshfree approach in peridynamics, nearest-neighbor discretizations do not reduce, in general, to discretizations of corresponding classical models. We study nodal-based quadratures for the discretization of peridynamic models, and we derive quadrature weights that result in consistency between nearest-neighbor discretizations of peridynamic models and discretized classical models. The quadrature weights that lead to such consistency are, however, model-/discretization-dependent. We motivate the choice of those quadrature weights through a quadratic approximation of displacement fields. The stability of nearest-neighbor peridynamic schemes is demonstrated through a Fourier mode analysis. Finally, an approach based on a normalization of peridynamic constitutive constants at the discrete level is explored. This approach results in the desired consistency for one-dimensional models, but does not work in higher dimensions. The results of the work presented in this paper suggest that even though nearest

  10. Effective conductivity and permittivity of unsaturated porous materials in the frequency range 1 mHz-1GHz.

    PubMed

    Revil, A

    2013-01-01

    A model combining low-frequency complex conductivity and high-frequency permittivity is developed in the frequency range from 1 mHz to 1 GHz. The low-frequency conductivity depends on pore water and surface conductivities. Surface conductivity is controlled by the electrical diffuse layer, the outer component of the electrical double layer coating the surface of the minerals. The frequency dependence of the effective quadrature conductivity shows three domains. Below a critical frequency fp , which depends on the dynamic pore throat size Λ, the quadrature conductivity is frequency dependent. Between fp and a second critical frequency fd , the quadrature conductivity is generally well described by a plateau when clay minerals are present in the material. Clay-free porous materials with a narrow grain size distribution are described by a Cole-Cole model. The characteristic frequency fd controls the transition between double layer polarization and the effect of the high-frequency permittivity of the material. The Maxwell-Wagner polarization is found to be relatively negligible. For a broad range of frequencies below 1 MHz, the effective permittivity exhibits a strong dependence with the cation exchange capacity and the specific surface area. At high frequency, above the critical frequency fd , the effective permittivity reaches a high-frequency asymptotic limit that is controlled by the two Archie's exponents m and n like the low-frequency electrical conductivity. The unified model is compared with various data sets from the literature and is able to explain fairly well a broad number of observations with a very small number of textural and electrochemical parameters. It could be therefore used to interpret induced polarization, induction-based electromagnetic methods, and ground penetrating radar data to characterize the vadose zone.

  11. Effective conductivity and permittivity of unsaturated porous materials in the frequency range 1 mHz–1GHz

    PubMed Central

    Revil, A

    2013-01-01

    A model combining low-frequency complex conductivity and high-frequency permittivity is developed in the frequency range from 1 mHz to 1 GHz. The low-frequency conductivity depends on pore water and surface conductivities. Surface conductivity is controlled by the electrical diffuse layer, the outer component of the electrical double layer coating the surface of the minerals. The frequency dependence of the effective quadrature conductivity shows three domains. Below a critical frequency fp, which depends on the dynamic pore throat size Λ, the quadrature conductivity is frequency dependent. Between fp and a second critical frequency fd, the quadrature conductivity is generally well described by a plateau when clay minerals are present in the material. Clay-free porous materials with a narrow grain size distribution are described by a Cole-Cole model. The characteristic frequency fd controls the transition between double layer polarization and the effect of the high-frequency permittivity of the material. The Maxwell-Wagner polarization is found to be relatively negligible. For a broad range of frequencies below 1 MHz, the effective permittivity exhibits a strong dependence with the cation exchange capacity and the specific surface area. At high frequency, above the critical frequency fd, the effective permittivity reaches a high-frequency asymptotic limit that is controlled by the two Archie's exponents m and n like the low-frequency electrical conductivity. The unified model is compared with various data sets from the literature and is able to explain fairly well a broad number of observations with a very small number of textural and electrochemical parameters. It could be therefore used to interpret induced polarization, induction-based electromagnetic methods, and ground penetrating radar data to characterize the vadose zone. PMID:23576823

  12. Dosimetric modeling of the microselectron high-dose rate 192Ir source by the multigroup discrete ordinates method.

    PubMed

    Daskalov, G M; Baker, R S; Rogers, D W; Williamson, J F

    2000-10-01

    The DANTSYS multigroup discrete ordinates computer code is applied to quantitatively estimate the absorbed dose rate distributions in the vicinity of a microSelectron 192Ir high-dose-rate (HDR) source in two-dimensional cylindrical R-Z geometry. The source is modeled in a cylindrical water phantom of diameter 20 cm and height 20 cm. The results are also used for evaluation of the Task Group 43 (TG-43) dosimetric quantities. The DANTSYS accuracy is estimated by direct comparisons with corresponding Monte Carlo results. Our 210-group photon cross section library developed previously, together with angular quadratures consisting of 36 (S16) to 210 (S40) directions and associated weights per octant, are used in the DANTSYS simulations. Strong ray effects are observed but are significantly mitigated through the use of DANTSYS's stochastic ray-tracing first collision source algorithm. The DANTSYS simulations closely approximate Monte Carlo estimates of both direct dose calculations and TG-43 dosimetric quantities. The discrepancies with S20 angular quadrature (55 directions and weights per octant) or higher are shown to be less than +/- 5% (about 2.5 standard deviations of Monte Carlo calculations) everywhere except for limited regions along the Z axis of rotational symmetry, where technical limitations in the DANTSYS first collision source implementation makes adequate suppression of ray effects difficult to achieve. The efficiency of DANTSYS simulations is compared with that of the EGS4 Monte Carlo code. It is demonstrated that even with the 210-group cross section library, DANTSYS achieves two-fold efficiency gains using the the S20 quadrature set. The potential of discrete ordinates method for further efficiency improvements is also discussed. PMID:11099199

  13. Exponential Monte Carlo convergence of a three-dimensional discrete ordinates solution

    SciTech Connect

    Favorite, J.A.; Lichtenstein, H.

    1999-07-01

    Recent work on obtaining exponential convergence for three-dimensional solutions to the spatially and angularly continuous monoenergetic transport equation with isotropic scattering using the reduced source method was promising. The method, however, used two separate estimates of the scalar flux, a Legendre expansion (in the spatial variables) and a quadrature of the angular flux. This introduced an inconsistency that may have led to some convergence problems. To remove this inconsistency and provide a fairer test of the combined reduced source/Monte Carlo method, the method was applied to estimate the coefficients of a Legendre expansion of the solution of the discrete ordinates equations. In this case, no supplementary approximations were required. The method was tested on a homogeneous three-dimensional slab of dimensions 1 x 10{sup 6} x 10{sup 6} cm and material parameters {Sigma}{sub t} = 1 and {Sigma}{sub s} = 0.5. The external source of Eq. (2) was S{sub m}(r{sub s}) = S{sub m}(0,y,z) = {mu}{sub m}, {mu}{sub m} {gt} 0. Figure 1 shows the results of the solution of the S{sub 8} equations using a standard quadrature set, 560,000 particles per stage (except the zeroth, in which only 80,000 particles were used), and Legendre expansions of order 10 in each direction with no Legendre product terms in Eq. (5). For this simple problem, Fig. 1 clearly shows exponential convergence of four different residuals and of two estimates of the known source. The difference between two Monte Carlo scalar fluxes (volume midpoint and volume average) and those estimated by THREE-DANT (Ref. 5) using the same S{sub s} quadrature set are shown for verification. For this problem, convergence was achieved after ten adaptive stages in 75.1 min.

  14. Selecting the kernel in a peridynamic formulation: A study for transient heat diffusion

    NASA Astrophysics Data System (ADS)

    Chen, Ziguang; Bobaru, Florin

    2015-12-01

    The kernel in a peridynamic diffusion model represents the detailed interaction between points inside the nonlocal region around each material point. Several versions of the kernel function have been proposed. Although solutions associated with different kernels may all converge, under the appropriate discretization scheme, to the classical model when the horizon goes to zero, their convergence behavior varies. In this paper, we focus on the particular one-point Gauss quadrature method of spatial discretization of the peridynamic diffusion model and study the convergence properties of different kernels with respect to convergence to the classical, local, model for transient heat transfer equation in 1D, where exact representation of geometry is available. The one-point Gauss quadrature is the preferred method for discretizing peridynamic models because it leads to a meshfree model, well suited for problems with damage and fracture. We show the equivalency of two definitions for the peridynamic heat flux. We explain an apparent paradox and discuss a common pitfall in numerical approximations of nonlocal models and their convergence to local models. We also analyze the influence of two ways of imposing boundary conditions and that of the "skin effect" on the solution. We explain an interesting behavior of the peridynamic solutions for different horizon sizes, the crossing of m-convergence curves at the classical solution value that happens for one of the ways of implementing the classical boundary conditions. The results presented here provide practical guidance in selecting the appropriate peridynamic kernel that makes the one-point Gauss quadrature an "asymptotically compatible" scheme. These results are directly applicable to any diffusion-type model, including mass diffusion problems.

  15. Quad-Chip Double-Balanced Frequency Tripler

    NASA Technical Reports Server (NTRS)

    Lin, Robert H.; Ward, John S.; Bruneau, Peter J.; Mehdi, Imran; Thomas, Bertrand C.; Maestrini, Alain

    2010-01-01

    Solid-state frequency multipliers are used to produce tunable broadband sources at millimeter and submillimeter wavelengths. The maximum power produced by a single chip is limited by the electrical breakdown of the semiconductor and by the thermal management properties of the chip. The solution is to split the drive power to a frequency tripler using waveguides to divide the power among four chips, then recombine the output power from the four chips back into a single waveguide. To achieve this, a waveguide branchline quadrature hybrid coupler splits a 100-GHz input signal into two paths with a 90 relative phase shift. These two paths are split again by a pair of waveguide Y-junctions. The signals from the four outputs of the Y-junctions are tripled in frequency using balanced Schottky diode frequency triplers before being recombined with another pair of Y-junctions. A final waveguide branchline quadrature hybrid coupler completes the combination. Using four chips instead of one enables using four-times higher power input, and produces a nearly four-fold power output as compared to using a single chip. The phase shifts introduced by the quadrature hybrid couplers provide isolation for the input and output waveguides, effectively eliminating standing waves between it and surrounding components. This is accomplished without introducing the high losses and expense of ferrite isolators. A practical use of this technology is to drive local oscillators as was demonstrated around 300 GHz for a heterodyne spectrometer operating in the 2-3-THz band. Heterodyne spectroscopy in this frequency band is especially valuable for astrophysics due to the presence of a very large number of molecular spectral lines. Besides high-resolution radar and spectrographic screening applications, this technology could also be useful for laboratory spectroscopy.

  16. Milne, a routine for the numerical solution of Milne's problem

    NASA Astrophysics Data System (ADS)

    Rawat, Ajay; Mohankumar, N.

    2010-11-01

    The routine Milne provides accurate numerical values for the classical Milne's problem of neutron transport for the planar one speed and isotropic scattering case. The solution is based on the Case eigen-function formalism. The relevant X functions are evaluated accurately by the Double Exponential quadrature. The calculated quantities are the extrapolation distance and the scalar and the angular fluxes. Also, the H function needed in astrophysical calculations is evaluated as a byproduct. Program summaryProgram title: Milne Catalogue identifier: AEGS_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 701 No. of bytes in distributed program, including test data, etc.: 6845 Distribution format: tar.gz Programming language: Fortran 77 Computer: PC under Linux or Windows Operating system: Ubuntu 8.04 (Kernel version 2.6.24-16-generic), Windows-XP Classification: 4.11, 21.1, 21.2 Nature of problem: The X functions are integral expressions. The convergence of these regular and Cauchy Principal Value integrals are impaired by the singularities of the integrand in the complex plane. The DE quadrature scheme tackles these singularities in a robust manner compared to the standard Gauss quadrature. Running time: The test included in the distribution takes a few seconds to run.

  17. Space-time decomposition of global Sea Surface Temperature variability using Multichannel Empirical Orthogonal Teleconnection analysis

    NASA Astrophysics Data System (ADS)

    Parmentier, B.; Neeti, N.; Eastman, R.

    2011-12-01

    With earth observation data, one of the primary concerns is the discovery of recurrent patterns over time. For example, the ENSO phenomenon is a major climatological pattern of global significance. As a spatial/two-dimensional extension of Singular Spectrum Analysis (SSA), Multichannel Singular Spectrum Analysis (MSSA) seeks to uncover the temporal evolution of recurrent space-time patterns within a specified time frame (known as the embedding dimension) by a method of spectral decomposition equivalent to Extended Principal Components Analysis. However, it suffers from the same limitations as PCA with regard to the propensity to develop components that are mixtures of multiple dominant patterns. In this paper we introduce a novel procedure we call Multichannel Empirical Orthogonal Teleconnection (MEOT) analysis as a simple extension of the logic of Empirical Orthogonal Teleconnections (EOT). A global sea surface temperature dataset spanning the 1982-2007 time period is utilized to explore the similarities and differences between MSSA and MEOT. The techniques are applied with a 13 month embedding dimension to extract spatio-temporal patterns that exhibit clear basis vectors in quadrature. Findings indicate that MEOT is capable of detecting more patterns in quadrature than MSSA. MEOT identifies three climate events as quadratures corresponding to the El Niño Southern Oscillation (ENSO), the Atlantic Meridional Mode (AMM) and the Atlantic Niño/ Tropical Southern Atlantic (TSA) mode. All of these climate events have phase change within a year. MSSA in contrast, only identified the ENSO event. Moreover, since MEOT does not suffer from a bi-orthogonality constraint, it is capable of extracting fewer mixed modes of variability than MSSA. Thus, results suggest a better identification and representation of individual climate events by the MEOT method.

  18. Computing traveltime and amplitude sensitivity kernels in finite-frequency tomography

    NASA Astrophysics Data System (ADS)

    Tian, Yue; Montelli, Raffaella; Nolet, Guust; Dahlen, F. A.

    2007-10-01

    The efficient computation of finite-frequency traveltime and amplitude sensitivity kernels for velocity and attenuation perturbations in global seismic tomography poses problems both of numerical precision and of validity of the paraxial approximation used. We investigate these aspects, using a local model parameterization in the form of a tetrahedral grid with linear interpolation in between grid nodes. The matrix coefficients of the linear inverse problem involve a volume integral of the product of the finite-frequency kernel with the basis functions that represent the linear interpolation. We use local and global tests as well as analytical expressions to test the numerical precision of the frequency and spatial quadrature. There is a trade-off between narrowing the bandpass filter and quadrature accuracy and efficiency. Using a minimum step size of 10 km for S waves and 30 km for SS waves, relative errors in the quadrature are of the order of 1% for direct waves such as S, and a few percent for SS waves, which are below data uncertainties in delay time or amplitude anomaly observations in global seismology. Larger errors may occur wherever the sensitivity extends over a large volume and the paraxial approximation breaks down at large distance from the ray. This is especially noticeable for minimax phases such as SS waves with periods >20 s, when kernels become hyperbolic near the reflection point and appreciable sensitivity extends over thousands of km. Errors becomes intolerable at epicentral distance near the antipode when sensitivity extends over all azimuths in the mantle. Effects of such errors may become noticeable at epicentral distances > 140°. We conclude that the paraxial approximation offers an efficient method for computing the matrix system for finite-frequency inversions in global tomography, though care should be taken near reflection points, and alternative methods are needed to compute sensitivity near the antipode.

  19. a Distributed Gaussian Discrete Variable Representation

    NASA Astrophysics Data System (ADS)

    Karabulut, Hasan

    In this work a discrete variable representation (DVR) is constructed from a distributed Gaussian basis (DGB). A DGB is a finite or infinite chain of uniformly distributed Gaussians g_{n}(x) = e^{-c^2(x/d-n)^2} where n takes integer values. There are three main parts of this thesis. In the first part (Chapter III) the finite chain distributed Gaussian DVR (Finite Chain DG-DVR) is derived. In order to accomplish this, the distributed Gaussian orthogonal polynomials are introduced. The connection of these polynomials to Stieltjes-Wigert polynomials is shown. The recurrence relation for these orthogonal polynomials is derived. Tested recipes are given to calculate the quadrature points and weights and to construct the corresponding Lagrange functions which are analogs of Lagrange interpolation polynomials. The symmetries of quadrature points, weights, and Lagrange functions are derived. Limit cases ctoinfty and cto 0 are studied. In the second part (Chapter IV)the infinite chain limit DG-DVR is derived from a limit of the finite chain DG-DVR. The quadrature points and weights and the Lagrange functions are found in this limit and kinetic energy operator is constructed. It is shown that in the limit c to 0 the infinite chain DG-DVR reduces to Colbert and Miller's DVR. A discussion of ability of a distributed Gaussian basis to represent an arbitrary function is given. The results of this treatment yield a possible explanation of surprising accuracy of Colbert-Miller DVR. In the third part construction of the DG-DVR is given when one point is chosen arbitrarily. Some interesting identities and integral representations for the b _{n} and sigma_ {n} coefficients that are introduced in the second part are found.

  20. Interferometric Sensor of Wavelength Detuning Using a Liquid Crystalline Polymer Waveplate.

    PubMed

    Wierzba, Paweł

    2016-01-01

    Operation of a polarization interferometer for measurement of the wavelength changes of a tunable semiconductor laser was investigated. A λ/8 waveplate made from liquid crystalline polymer is placed in one of interferometers' arms in order to generate two output signals in quadrature. Wavelength was measured with resolution of 2 pm in the wavelength range 628-635 nm. Drift of the interferometer, measured in the period of 500 s, was 8 nm, which corresponded to the change in the wavelength of 1.3 pm. If needed, wavelength-dependent Heydemann correction can be used to expand the range of operation of such interferometer. PMID:27171082

  1. Non-Periodic Finite-Element Formulation of Orbital-Free Density Functional Theory

    SciTech Connect

    Gavini, V; Knap, J; Bhattacharya, K; Ortiz, M

    2006-10-06

    We propose an approach to perform orbital-free density functional theory calculations in a non-periodic setting using the finite-element method. We consider this a step towards constructing a seamless multi-scale approach for studying defects like vacancies, dislocations and cracks that require quantum mechanical resolution at the core and are sensitive to long range continuum stresses. In this paper, we describe a local real space variational formulation for orbital-free density functional theory, including the electrostatic terms and prove existence results. We prove the convergence of the finite-element approximation including numerical quadratures for our variational formulation. Finally, we demonstrate our method using examples.

  2. Singularity Preserving Numerical Methods for Boundary Integral Equations

    NASA Technical Reports Server (NTRS)

    Kaneko, Hideaki (Principal Investigator)

    1996-01-01

    In the past twelve months (May 8, 1995 - May 8, 1996), under the cooperative agreement with Division of Multidisciplinary Optimization at NASA Langley, we have accomplished the following five projects: a note on the finite element method with singular basis functions; numerical quadrature for weakly singular integrals; superconvergence of degenerate kernel method; superconvergence of the iterated collocation method for Hammersteion equations; and singularity preserving Galerkin method for Hammerstein equations with logarithmic kernel. This final report consists of five papers describing these projects. Each project is preceeded by a brief abstract.

  3. A study of methods to predict and measure the transmission of sound through the walls of light aircraft. Integration of certain singular boundary element integrals for applications in linear acoustics

    NASA Technical Reports Server (NTRS)

    Zimmerle, D.; Bernhard, R. J.

    1985-01-01

    An alternative method for performing singular boundary element integrals for applications in linear acoustics is discussed. The method separates the integral of the characteristic solution into a singular and nonsingular part. The singular portion is integrated with a combination of analytic and numerical techniques while the nonsingular portion is integrated with standard Gaussian quadrature. The method may be generalized to many types of subparametric elements. The integrals over elements containing the root node are considered, and the characteristic solution for linear acoustic problems are examined. The method may be generalized to most characteristic solutions.

  4. Lie symmetry and integrability of ordinary differential equations

    NASA Astrophysics Data System (ADS)

    Zhdanov, R. Z.

    1998-12-01

    Combining a Lie algebraic approach that is due to Wei and Norman [J. Math. Phys. 4, 475 (1963)] and the ideas suggested by Drach [Compt. Rend. 168, 337 (1919)], we have constructed several classes of systems of linear ordinary differential equations that are integrable by quadratures. Their integrability is ensured by integrability of the corresponding stationary cubic Schrödinger, KdV, and Harry-Dym equations. Next, we obtain a hierarchy of integrable reductions of the Dirac equation of an electron moving in the external field. Their integrability is shown to be in correspondence with integrability of the stationary mKdV hierarchy.

  5. Entangled State Representation for Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Ma, Shan-Jun; Lu, Hai-Liang; Fan, Hong-Yi

    2008-08-01

    We introduce the entangled state representation to describe the four-wave mixing. We find that the four-wave mixing operator, which engenders the correct input-output field transformation, has a natural representation in the entangled state representation. In this way, we see that the four-wave mixing process not only involves squeezing but also is an entanglement process. This analysis brings convenience to the calculation of quadrature-amplitude measurement for the output state of four-wave mixing process.

  6. Evaluation of 3D radio-frequency electromagnetic fields for any matching and coupling conditions by the use of basis functions

    NASA Astrophysics Data System (ADS)

    Tiberi, Gianluigi; Fontana, Nunzia; Monorchio, Agostino; Stara, Riccardo; Retico, Alessandra; Tosetti, Michela

    2015-12-01

    A procedure for evaluating radio-frequency electromagnetic fields in anatomical human models for any matching and coupling conditions is introduced. The procedure resorts to the extraction of basis functions: such basis functions, which represent the fields produced by each individual port without any residual coupling, are derived through an algebraic procedure which uses the S parameter matrix and the fields calculated in one (only) full-wave simulation. The basis functions are then used as building-blocks for calculating the fields for any other S parameter matrix. The proposed approach can be used both for volume coil driven in quadrature and for parallel transmission configuration.

  7. Combined GMSK Communications and PN Ranging

    NASA Technical Reports Server (NTRS)

    Orr, Richard; Divsalar, Dariush

    2008-01-01

    A document discusses a method by which GMSK (Gaussian minimum shift keying) modulation and a pseudonoise (PN) ranging signal may be combined. By isolating the in-phase and quadrature components after carrier lock, and extracting their low-pass and band-pass filtered components, there is enough information available to both demodulate data and track the PN signal. The proposed combined GMSK communications and PN ranging is one potential approach to address emerging requirements for simultaneous high data rate communications from and tracking of vehicles in deep space or at the Moon.

  8. High-speed horizontal-path atmospheric turbulence correction using a large actuator-number MEMS spatial light modulator in an interferometric phase conjugation engine

    SciTech Connect

    Baker, K; Stappaerts, E; Gavel, D; Wilks, S; Tucker, J; Silva, D; Olsen, J; Olivier, S; Young, P; Kartz, M; Flath, L; Kruelivitch, P; Crawford, J; Azucena, O

    2004-03-04

    Atmospheric propagation results for a high-speed, large-actuator-number, adaptive optics system are presented. The system uses a MEMS-based spatial light modulator correction device with 1024 actuators. Tests over a 1.35 km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large actuator number MEMS-based spatial light modulators to replace conventional deformable mirrors.

  9. Simultaneous detection of 10-Gbit/s QPSK × 2-ch. Fourier-encoded synchronous OCDM signals with digital coherent receiver.

    PubMed

    Okamura, Yasuhiro; Iijima, Osamu; Shimizu, Satoshi; Wada, Naoya; Hanawa, Masanori

    2013-02-11

    We experimentally demonstrate the simultaneous detection of 10-Gbit/s quadrature phase shift keying (QPSK) × 2-channel Fourier-encoded synchronous optical code division multiplexing (FE-SOCDM) signals using a digital coherent receiver, for the first time. First, we analytically verify that simultaneous detection can be achieved with an N-point discrete Fourier transform (DFT) using digital signal processing (DSP) because the N-channel Fourier encoding corresponds to an N × N inverse DFT, then the operation is experimentally confirmed. Simultaneous detection of 10-Gbit/s QPSK × 2-channel FE-SOCDM signals is evaluated. The proposed scheme dramatically expands the capability of OCDM systems.

  10. High-Rate Wireless Airborne Network Demonstration (HiWAND) Flight Test Results

    NASA Technical Reports Server (NTRS)

    Franz, Russell

    2007-01-01

    An increasing number of flight research and airborne science experiments now contain network-ready systems that could benefit from a high-rate bidirectional air-to-ground network link. A prototype system, the High-Rate Wireless Airborne Network Demonstration, was developed from commercial off-the-shelf components while leveraging the existing telemetry infrastructure on the Western Aeronautical Test Range. This approach resulted in a cost-effective, long-range, line-of-sight network link over the S and the L frequency bands using both frequency modulation and shaped-offset quadrature phase-shift keying modulation. This paper discusses system configuration and the flight test results.

  11. Hybrid polarity SAR architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. Keith

    2009-05-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs, reviews the associated advantages, formalizes conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  12. Hybrid-Polarity SAR Architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. K.; Freeman, A.

    2009-04-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper reviews those advantages,summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs including conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  13. Sqeezing generated by a nonlinear master equation and by amplifying-dissipative Hamiltonians

    NASA Technical Reports Server (NTRS)

    Dodonov, V. V.; Marchiolli, M. A.; Mizrahi, Solomon S.; Moussa, M. H. Y.

    1994-01-01

    In the first part of this contribution we show that the master equation derived from the generalized version of the nonlinear Doebner-Goldin equation leads to the squeezing of one of the quadratures. In the second part we consider two familiar Hamiltonians, the Bateman- Caldirola-Kanai and the optical parametric oscillator; going back to their classical Lagrangian form we introduce a stochastic force and a dissipative factor. From this new Lagrangian we obtain a modified Hamiltonian that treats adequately the simultaneous amplification and dissipation phenomena, presenting squeezing, too.

  14. High-Rate Wireless Airborne Network Demonstration (HiWAND) Flight Test Results

    NASA Technical Reports Server (NTRS)

    Franz, Russell

    2008-01-01

    An increasing number of flight research and airborne science experiments now contain network-ready systems that could benefit from a high-rate bidirectional air-to-ground network link. A prototype system, the High-Rate Wireless Airborne Network Demonstration, was developed from commercial off-the-shelf components while leveraging the existing telemetry infrastructure on the Western Aeronautical Test Range. This approach resulted in a cost-effective, long-range, line-of-sight network link over the S and the L frequency bands using both frequency modulation and shaped-offset quadrature phase-shift keying modulation. This report discusses system configuration and the flight test results.

  15. Spatial resolution enhancement of fiber-optic scanning white-light interferometer by use of a Vernier principle.

    PubMed

    Sun, Changsen; Zhao, Yang; Tennant, Adam; Ansari, Farhad

    2003-08-01

    A Vernier principle is employed to improve the spatial resolution of a fiber-optic white-light interferometer to the accuracy of 0.2 microm. The Vernier principle is implemented by combination of interference fringes itself and a virtual fringe that is generated by means of software tracing the scanning mirror. Two rulers are read with respect to each other. This design is insensitive to intensity fluctuation of the interference fringe. The applications, submicrometer estimation for the quadrature-locking selection and the tolerance of the relative measurement, demonstrate its effectiveness.

  16. Integrated low power digital gyro control electronics

    NASA Technical Reports Server (NTRS)

    M'Closkey, Robert (Inventor); Challoner, A. Dorian (Inventor); Grayver, Eugene (Inventor); Hayworth, Ken J. (Inventor)

    2005-01-01

    Embodiments of the invention generally encompass a digital, application specific integrated circuit (ASIC) has been designed to perform excitation of a selected mode within a vibratory rate gyroscope, damping, or force-rebalance, of other modes within the sensor, and signal demodulation of the in-phase and quadrature components of the signal containing the angular rate information. The ASIC filters dedicated to each channel may be individually programmed to accommodate different rate sensor designs/technology or variations within the same class of sensors. The ASIC architecture employs a low-power design, making the ASIC, particularly suitable for use in power-sensitive applications.

  17. An approximate atmospheric guidance law for aeroassisted plane change maneuvers

    NASA Astrophysics Data System (ADS)

    Speyer, Jason L.; Crues, Edwin Z.

    An approximate optimal guidance law for the aeroassisted plane change problem is presented which is based upon an expansion of the Hamilton-Jacobi-Bellman equation with respect to the small parameter of Breakwell et al. (1985). The present law maximizes the final velocity of the reentry vehicle while meeting terminal constraints on altitude, flight path angle, and heading angle. The integrable zeroth-order solution found when the small parameter is set to zero corresponds to a solution of the problem where the aerodynamic forces dominate the inertial forces. Higher order solutions in the expansion are obtained from the solution of linear partial differential equations requiring only quadrature integration.

  18. Practical limitation for continuous-variable quantum cryptography using coherent States.

    PubMed

    Namiki, Ryo; Hirano, Takuya

    2004-03-19

    In this Letter, first, we investigate the security of a continuous-variable quantum cryptographic scheme with a postselection process against individual beam splitting attack. It is shown that the scheme can be secure in the presence of the transmission loss owing to the postselection. Second, we provide a loss limit for continuous-variable quantum cryptography using coherent states taking into account excess Gaussian noise on quadrature distribution. Since the excess noise is reduced by the loss mechanism, a realistic intercept-resend attack which makes a Gaussian mixture of coherent states gives a loss limit in the presence of any excess Gaussian noise.

  19. Generalization of continuous-variable quantum cloning with linear optics

    SciTech Connect

    Zhai Zehui; Guo Juan; Gao Jiangrui

    2006-05-15

    We propose an asymmetric quantum cloning scheme. Based on the proposal and experiment by Andersen et al. [Phys. Rev. Lett. 94, 240503 (2005)], we generalize it to two asymmetric cases: quantum cloning with asymmetry between output clones and between quadrature variables. These optical implementations also employ linear elements and homodyne detection only. Finally, we also compare the utility of symmetric and asymmetric cloning in an analysis of a squeezed-state quantum key distribution protocol and find that the asymmetric one is more advantageous.

  20. Entanglement of mixed macroscopic superpositions: An entangling-power study

    SciTech Connect

    Paternostro, M.; Kim, M. S.; Jeong, H.

    2006-01-15

    We investigate entanglement properties of a recently introduced class of macroscopic quantum superpositions in two-mode mixed states. One of the tools we use in order to infer the entanglement in this non-Gaussian class of states is the power to entangle a qubit system. Our study reveals features which are hidden in a standard approach to entanglement investigation based on the uncertainty principle of the quadrature variables. We briefly describe the experimental setup corresponding to our theoretical scenario and a suitable modification of the protocol which makes our proposal realizable within the current experimental capabilities.