Etude de Cavités Electromagnétiques Perturbées par un Diélectrique : Application aux Masers

1971 ◽  
Vol 49 (11) ◽  
pp. 1482-1492 ◽  
Author(s):  
M. Tessier ◽  
J. Vanier
Keyword(s):  
Frequency Shift ◽  
Quality Factor ◽  
Method Of Moments ◽  
Filling Factor ◽  
The Other ◽  
Microwave Cavities ◽  
Negative Frequency Shift ◽  
Theoretical Results

In certain types of masers it is common to use storage quartz bulbs in microwave cavities. We describe the effects of such bulbs on the field components, the frequency, the quality factor, and the filling factor. Two different methods are used to solve the problem: one of these methods is classical and exact and is based on the continuity of the field components and on the equations of separation; the other method used is the so called "method of moments". The two methods give essentially the same results. Experiments have been performed to verify the theoretical results. We have observed that the quartz storage bulb produces a slight negative frequency shift, a notable lowering of the quality factor and a very slight change in the filling factor; the perturbed mode appears as a superposition of other modes. It is concluded that to reduce the perturbation we must use extremely thin bulbs with walls very close to the cavity walls.

On the kinetics of Hadamard-type fractional differential systems

2020 ◽  
Vol 23 (2) ◽  
pp. 553-570 ◽  
Author(s):  
Li Ma
Keyword(s):  
Differential Operator ◽  
Numerical Simulations ◽  
Type Inequality ◽  
The Other ◽  
Differential Systems ◽  
Fractional Differential Systems ◽  
Fractional Differential Operator ◽  
Fractional Differential ◽  
Kinetics Of ◽  
Theoretical Results

AbstractThis paper is devoted to the investigation of the kinetics of Hadamard-type fractional differential systems (HTFDSs) in two aspects. On one hand, the nonexistence of non-trivial periodic solutions for general HTFDSs, which are considered in some functional spaces, is proved and the corresponding eigenfunction of Hadamard-type fractional differential operator is also discussed. On the other hand, by the generalized Gronwall-type inequality, we estimate the bound of the Lyapunov exponents for HTFDSs. In addition, numerical simulations are addressed to verify the obtained theoretical results.

STRONG AND WEAK FORMS OF THE METHOD OF MOMENTS AND THE COUPLED DIPOLE METHOD FOR SCATTERING OF TIME-HARMONIC ELECTROMAGNETIC FIELDS

1992 ◽  
Vol 03 (03) ◽  
pp. 583-603 ◽  
Author(s):  
AKHLESH LAKHTAKIA
Keyword(s):  
Electromagnetic Fields ◽  
Method Of Moments ◽  
Electromagnetic Scattering ◽  
Final Section ◽  
The Other ◽  
Numerical Techniques ◽  
Scattering Problems ◽  
Time Harmonic

Algorithms based on the method of moments (MOM) and the coupled dipole method (CDM) are commonly used to solve electromagnetic scattering problems. In this paper, the strong and the weak forms of both numerical techniques are derived for bianisotropic scatterers. The two techniques are shown to be fully equivalent to each other, thereby defusing claims of superiority often made for the charms of one technique over the other. In the final section, reductions of the algorithms for isotropic dielectric scatterers are explicitly given.

scholarly journals General Minimum Lower-Order Confounding Designs with Multi-Block Variables

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuna Zhao
Keyword(s):  
Lower Order ◽  
Treatment Effects ◽  
The Other ◽  
Construction Methods ◽  
Block Variables ◽  
Single Block ◽  
Theoretical Results

Blocking the inhomogeneous units of experiments into groups is an efficient way to reduce the influence of systematic sources on the estimations of treatment effects. In practice, there are two types of blocking problems. One considers only a single block variable and the other considers multi-block variables. The present paper considers the blocking problem of multi-block variables. Theoretical results and systematical construction methods of optimal blocked 2 n − m designs with N / 4 + 1 ≤ n ≤ 5 N / 16 are developed under the prevalent general minimum lower-order confounding (GMC) criterion, where N = 2 n − m .

scholarly journals Competitive Analysis for Online Leasing Problem with Compound Interest Rate

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Xingyu Yang ◽  
Weiguo Zhang ◽  
Weijun Xu ◽  
Yong Zhang
Keyword(s):  
Interest Rate ◽  
Competitive Analysis ◽  
The Other ◽  
Continuous Version ◽  
Numerical Examples ◽  
The Interest Rate ◽  
The One ◽  
Compound Interest ◽  
Theoretical Results ◽  
Deterministic Strategy

We introduce the compound interest rate into the continuous version of the online leasing problem and discuss the generalized model by competitive analysis. On the one hand, the optimal deterministic strategy and its competitive ratio are obtained; on the other hand, a nearly optimal randomized strategy is constructed and a lower bound for the randomized competitive ratios is proved by Yao's principle. With the help of numerical examples, the theoretical results show that the interest rate puts off the purchase date and diminishes the uncertainty involved in the decision making.

Re-adjustments for MOM calculations of microstrip and stripline power dissipation

2020 ◽  
pp. 1-11
Author(s):  
Frederick Huang
Keyword(s):  
Magnetic Field ◽  
Method Of Moments ◽  
Current Density ◽  
Power Dissipation ◽  
Finite Thickness ◽  
The Other ◽  
Integration Limit ◽  
Large Current ◽  
Large Current Density ◽  
Parallel Strips

Abstract Microstrip and stripline losses in Method of Moments (MOM) calculations have an error arising from the large current density at the strip edges, characterized by an integration limit (W/2-d) in the equation for current density in thin strips (width W), where d is a fitting parameter. It depends primarily on the width of the MOM subsection on the edge of the strip. By comparing with the integration limit (W/2-Δ) for an actual strip with finite thickness, a correction factor is estimated. The equations incorporating d are confirmed by comparing with MOM calculations of isolated stripline, uniformly spaced parallel strips, striplines and microstrips close to ground planes, and with a strip in a uniform, externally applied magnetic field. The results are also consistent with measurements with copper. This makes the accuracy of the loss estimates commensurate with the excellence of the other aspects of MOM simulations.

Estimation of quality factor based on peak frequency-shift method and redatuming operator: Application in real data set

Geophysics ◽  
2017 ◽  
Vol 82 (1) ◽  
pp. N1-N12 ◽  
Author(s):  
Francisco de S. Oliveira ◽  
Jose J. S. de Figueiredo ◽  
Andrei G. Oliveira ◽  
Jörg Schleicher ◽  
Iury C. S. Araújo
Keyword(s):  
Frequency Shift ◽  
Quality Factor ◽  
Real Data ◽  
Peak Frequency ◽  
Accurate Estimation ◽  
Layer By Layer ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Energy Dissipated ◽  
Factor Estimation

Quality factor estimation and correction are necessary to compensate the seismic energy dissipated during acoustic-/elastic-wave propagation in the earth. In this process, known as [Formula: see text]-filtering in the realm of seismic processing, the main goal is to improve the resolution of the seismic signal, as well as to recover part of the energy dissipated by the anelastic attenuation. We have found a way to improve [Formula: see text]-factor estimation from seismic reflection data. Our methodology is based on the combination of the peak-frequency-shift (PFS) method and the redatuming operator. Our innovation is in the way we correct traveltimes when the medium consists of many layers. In other words, the correction of the traveltime table used in the PFS method is performed using the redatuming operator. This operation, performed iteratively, allows a more accurate estimation of the [Formula: see text] factor layer by layer. Applications to synthetic and real data (Viking Graben) reveal the feasibility of our analysis.

Integrity of Old Pipelines Buried in Petroleum Products Storage Terminals

2008 ◽  
Author(s):  
Mauro Y. Fujikawa ◽  
Eduardo O. de A. Silva ◽  
Reinaldo A. das Neves ◽  
Derci Donizeti Massitelli ◽  
Newton Orlando Abraha˜o ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
High Viscosity ◽  
Petroleum Products ◽  
The Other ◽  
Fuel Oil ◽  
Marine Fuel ◽  
Analysis Study ◽  
Theoretical Results

This work aims to present the results obtained from the experience gained through the accomplishment of the inspection with the ultrasonic umbilical pig in a non-piggable internal pipe buried in the Transpetro Storage Terminal in Sa˜o Caetano do Sul, in Sa˜o Paulo, Brazil. The pipeline considered in this work is a line for marine fuel oil, which, because of its high viscosity, must be heated in order to flow. The oil is heated in the terminal by the steam produced in boilers. The heat transfer may occur in a heat exchanger or inside the storage tank, and the pipeline referred is thermally isolated. So that the line could be inspected, it was divided in two parts, one upstream of the pumps (suction), which is a 12-inch line, and the other downstream of the same pumps (discharge), which is a 14-inch line. This work has been developed by Transpetro’s Pipeline Operation, Maintenance, Inspection and Safety Departments together, since the planning phase, passing by the job execution and getting to the conclusion. To begin with, the operational liberation of the line had to be agreed between all the departments involved with the PIG inspection, which were mentioned before, and Transpetro’s Logistics Department. Once the PIG passage was scheduled, an initial cleaning had to be performed by the Operation Activity. Since this line is non-piggable, the installation of adaptations was necessary. After that, the passage of cleaning PIGs was possible, and the line sections could be enabled. The next step was the inspection of the pipeline with umbilical ultrasonic PIGs. After the passage of these PIGs, the adaptations had to be removed and the pipeline had to be conditioned for the operational return. After this part of the inspection was finished, the verification of the results issued was necessary. Once the theoretical results were available, ditches were opened for correlation inspection and temporary repairs in the most critical points for the operation were applied. The last part of the work consists in an analysis study of technical and economical viability for rehabilitation of the lines.

Numerical Simulation of Inclined Injection of Polydisperse Polykinetic Spray in a Crossflow Using Quadrature Method of Moments

2014 ◽  
Author(s):  
Sudeepta Mondal ◽  
Achintya Mukhopadhyay
Keyword(s):  
Method Of Moments ◽  
Gas Turbines ◽  
Carrier Phase ◽  
Liquid Fuel ◽  
The Other ◽  
Quadrature Method ◽  
Vertical Injection ◽  
Quadrature Method Of Moments ◽  
Scramjet Combustors ◽  
Vertical Size

Liquid fuel is introduced as spray into a gaseous crossflow in many combustion applications like afterburners in gas turbines, ramjet and scramjet combustors. The transport phenomenon of a polydisperse polykinetic spray injected with an inclination in a crossflow has been analysed using Quadrature Method of Moments. Providing an inclination angle to the spray has been accompanied with a more or less uniform distribution of particles, unlike a distinct segregation of larger and smaller diameter particles as observed in the case of vertical injection. The upstream inclined injection in the crossflow yielded a region of stagnation of particles, irrespective of their sizes. This region corresponds to the location where the spray particles equilibrate with the crossflow, whereby they lose their momentum and are swept away by the carrier phase. The downstream injection, on the other hand, showed distinct horizontal and vertical size-based segregation along with regions of accumulation of particles.

scholarly journals Analysis of a Two-Level Algorithm for HDG Methods for Diffusion Problems

2016 ◽  
Vol 19 (5) ◽  
pp. 1435-1460 ◽  
Author(s):  
Binjie Li ◽  
Xiaoping Xie ◽  
Shiquan Zhang
Keyword(s):  
Convergence Rate ◽  
Numerical Experiments ◽  
Sharp Estimate ◽  
Model Problem ◽  
The Other ◽  
Extended Version ◽  
Weak Galerkin ◽  
Hybridizable Discontinuous Galerkin ◽  
Theoretical Results ◽  
Diffusion Problems

AbstractThis paper analyzes an abstract two-level algorithm for hybridizable discontinuous Galerkin (HDG) methods in a unified fashion. We use an extended version of the Xu-Zikatanov (X-Z) identity to derive a sharp estimate of the convergence rate of the algorithm, and show that the theoretical results also are applied to weak Galerkin (WG) methods. The main features of our analysis are twofold: one is that we only need the minimal regularity of the model problem; the other is that we do not require the triangulations to be quasi-uniform. Numerical experiments are provided to confirm the theoretical results.

Rectilinear low-frequency shear of homogeneously aligned nematic liquid crystals

1993 ◽  
Vol 441 (1913) ◽  
pp. 559-573 ◽  
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Theoretical Analysis ◽  
Low Frequency ◽  
The Other ◽  
Critical Amplitude ◽  
Linear Shear ◽  
Theoretical Results ◽  
Good Agreement

A thin film of nematic liquid crystal (ZLI 1085) is sandwiched between two horizontally mounted glass blocks, whose faces have been treated to align the molecules of the liquid parallel to the plane of the blocks. By moving one block relative to the other in its own plane, the liquid crystal is subjected to an oscillatory linear shear. Above a certain frequency-dependent amplitude, mechanical Williams domains of alternating bright and dark stripes are observed perpendicular to the direction of shear. A theoretical analysis of this phenomenon is carried out to provide predictions for both the thickness of the stripes and the critical amplitude as a function of frequency. Good agreement is found between the experimental and theoretical results.

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