Double Quadrature Research Articles

OFDM With Double Quadrature Signed Index Shift Keying

OFDM With Double Quadrature Signed Index Shift Keying

Numerical convergence of the family of flux-continuous schemes with variable quadrature (qu1,qu2) for single phase flow in porous media

Finite-volume schemes, which honor pressure and flux-continuity conditions, is developed using double quadrature (qu1,qu2), referred as double family scheme. The scheme is applicable to solve the elliptic pressure equation used in reservoir simulation. Schemes are applicable on both regular cartesian and unstructured triangular meshes. The scheme is defined over a control-volume distributed formulation. The scheme can be applied to both diagonal and full permeability tensor elliptic pressure equation with discontinuous coefficients. The scheme removes the first order errors, which are introduced by standard reservoir simulation schemes when applied to full tensor flow. The scheme is quantified with help of a quadrature rule. When the scheme is applied to highly heterogeneous and anisotropic porous media it does not honor maximum principle resulting in unstable solution with oscillatory behavior. The numerical solution is termed non-monotonicity for high anisotropy ratios with results showing oscillations in the numerical pressure solution. In this paper a double (qu1,qu2) quadrature flux continuous schemes is presented, which with specific choice of quadrature (qu1,qu2) helps in improved stability of the numerical solutions. Numerical convergence of the scheme is also demonstrated with help of a number of numerical test cases and schemes impact on monotonicity behavior is also demonstrated with numerical examples.

100G silicon optical modulator automatic bias control technology based on nonlinear effect compensation and thermal crosstalk effect compensation

The nonlinear effect and the thermal crosstalk effect are two major characteristics of silicon optical modulators that are different from LiNbO3 modulators. This paper proposes a new automatic bias control method of a 100G double polarization quadrature phase shift keying silicon optical modulator, including automatic bias control technology of the nonlinear effect compensation method and the thermal crosstalk effect compensation method. The experimental results show that the method can establish the linear relationship between the bias voltage and the phase of a silicon optical modulator. This new technology is proved to be feasible and practical by experiments.

Application of the Array Scanning Method in Periodic Structures with Large Periods

The problem of aperiodic excitation of periodic structures with periods larger than a half-wavelength is revisited. A large number of antennas and other electromagnetic wave propagation problems fall within this category. Because of overlapping branch cuts, the conventional path deformation techniques employed in application of the array scanning method for this type of problem fail when the period is larger than a half-wavelength. A new method based on the subdivision of the integration path and using the double exponential quadrature formula is introduced to alleviate this problem and apply the array scanning method to structures with an arbitrary spatial period. To demonstrate the application of the new method and to validate the results, reflection and transmission coefficients of a frequency selective surface excited by a single electric dipole are calculated. Near fields of the frequency selective surface with aperiodic excitation are obtained and compared with those of a commercial electromagnetic simulator. The proposed method, similar to the path deformation technique, which is applicable to small periods, shows considerable advantage in terms of computational time and memory requirement.

The Dirichlet and Neumann and Dirichlet-to-Neumann problems in quadrature, double quadrature, and non-quadrature domains

We demonstrate that solving the classical problems mentioned in the title on quadrature domains when the given boundary data is rational is as simple as the method of partial fractions. A by-product of our considerations will be a simple proof that the Dirichlet-to-Neumann map on a double quadrature domain sends rational functions on the boundary to rational functions on the boundary. The results extend to more general domains if rational functions are replaced by the class of functions on the boundary that extend meromorphically to the double.

Double-Quadrature UWB Receiver for Wide-Range Localization Applications With Sub-cm Ranging Precision

The interest of industry for localization technologies is growing, because of their ability to allow a wide variety of applications. Among the different technologies, UWB is known to potentially offer the best precision. This paper presents a fully integrated low-power UWB impulse radio receiver dedicated to communication and ranging applications. The new architecture based on double quadrature is used to reach sub-cm ranging precision while limiting the speed requirements and complexity of ADC and digital signal processing. Much attention has been paid to rejecting the out-of-band signals which could degrade receiver performance while fully exploiting the available spectrum in the [3-5 GHz] band. The 5.8-mm2 0.13- μm CMOS receiver consumes 50 mW at 50-Mb/s maximum data rate. It shows -95-dBm sensitivity at 1 Mb/s and 2.5-mm maximum ranging error at 10 m.

Benchmark results for the critical slab and sphere problem in one-speed neutron transport theory

In this paper benchmark numerical results for the one-speed criticality problem with isotropic scattering for the slab and sphere are reported. The Fredholm integral equations of the second kind based on the Case eigenfunction formalism are numerically solved by Neumann iterations with the Double Exponential quadrature.

A Low-Voltage High-Gain Quadrature Up-Conversion 5 GHz CMOS RF Mixer

A low-voltage quadrature up-conversion CMOS mixer for 5-GHz wireless communication applications is designed with a TSMC 0.18-µm process. The fold-switching technique is used to implement the low-voltage double balanced quadrature mixer. A miniature lumped-element microwave broadband rat-race hybrid and RLC shift network are used for the local oscillator and the intermediate frequency port design, respectively. The measured results demonstrate that the mixer can reach a high conversion gain, a low noise figure (NF), and a high linearity. The mixer exhibits improvement in noise, conversion gain, and image rejection. The mixer shows a conversion gain of 16dB, a noise figure of 12.8dB, an image rejection of 45dB, while dissipating 15.5mW for an operating voltage at 1V.

Spatial moments of a kinetically sorbing solute plume in a heterogeneous aquifer

Steady water flow takes place in a heterogeneous aquifer of a three‐dimensional random stationary log conductivity of anisotropic, axisymmetric co variance. The latter has different vertical and horizontal integral scales of anisotropy ratio e. The mean flow is uniform in the horizontal plane. A solute plume of constant concentration is injected instantaneously in the formation. The plume is characterized by the expected values of its spatial moments: mass, centroid coordinates, and tensor of second spatial moment. Under ergodic conditions, assumed to prevail, the one‐realization spatial moments are approximately equal to their ensemble means. By adopting a first‐order approximation in the log conductivity variance and with neglect of pore‐scale dispersion, the spatial moments of a plume of a conservative solute were evaluated in the past as functions of the transport time or distance from the input zone (Dagan, 1988) by a Lagrangian approach. The moments were expressed in terms of a quadrature that had to be evaluated numerically. The present study generalizes these results to a reactive solute which undergoes kinetically controlled sorption, according to a linear relationship. The reaction depends on two coefficients: a reaction time tr and an equilibrium partition coefficient Kd, which are assumed to be constant. The solution of the transport problem is obtained by the Lagrangian approach, generalizing the one applied previously to conservative solutes. In the latter case, solute particles follow those of the fluid, whereas a wake of solute is left behind in the case of sorption. The zero‐order spatial moment, the plume mass, the first‐order approximation, and the centroid coordinates are determined in an analytical form. They depend only on the mean velocity and on the reaction coefficients. The second‐order longitudinal moment, characterizing dispersion with respect to the centroid, is made up from terms depending only on the reaction and on an interactive term which depends also on heterogeneity. The latter is effectively derived by a double quadrature as well as by an analytical approximate expression, presented here for the first time. The transverse spatial moments contain only interaction terms. The third spatial moment, characterizing the asymmetry of the plume, is also evaluated. Simple asymptotic results are presented for the cases of (1) large transport time reaction time ratio, resulting in retardation, (2) large transport time heterogeneity characteristic time ratio, for which the longitudinal transport of the conservative solute is “Fickian,” and (3) the joint limit, resulting also in a “Fickian” regime.

Perturbation Theory for Charged-Particle Transport in One Dimension

Perturbation theory, when applied to charged-particle transport, generates a series solution that requires a double quadrature per term. The continuity of higher-order terms leads to numerical evaluation of the series. The high rate of convergence of the series makes the method a practical tool for charged-particle transport problems. The coupling of the neutron component in the case of proton transport in tissue does not greatly alter the rate of convergence. The method holds promise for a practical high-energy proton transport theory.

Total Illumination in a Diffraction Image Containing Spherical Aberration*

The total illumination (or encircled energy) in a diffraction image containing spherical aberration is studied for various amounts of third- and fifth-order aberration. The Zernike polynomials are used to represent spherical aberration. The evaluation of the total illumination was done numerically, using double Gauss quadrature and 49 quadrature points. Contour maps of the total illumination were constructed and compared with the aberration-free case examined previously by E. Wolf.

The Influence of Blast Characteristics on the Final Deformation of Circular Cylindrical Shells

Abstract The final maximum deformation of a reinforced circular cylindrical shell caused by a briefly applied, intense loading is considered. The maximum deformation is obtained in a form which requires a double quadrature of the pressure where the limits of the integration are determined from side conditions. Attempts are made to find a simple analytic approximation, but the attempts are unsuccessful for loads of practical importance. A straightforward graphical-numerical method of solution is devised. Several examples are considered in support of the conclusions. The shell is assumed to be infinitely long, so that end effects may be neglected. The load is assumed to be applied to the entire shell simultaneously. The shell is assumed a perfect cylinder, and the reinforcements are taken as rigid. Finally, the shell is assumed to be made of an ideal rigid-plastic material which satisfies a certain simplified yield condition and the associated flow rule.

Table of Coefficients for Double Quadrature Without Difference, for Integrating Second Order Differential Equations

Table of Coefficients for Double Quadrature Without Difference, for Integrating Second Order Differential Equations