An accurate method for determining the Q factor of a resonant cavity

1968 ◽  
Vol 46 (12) ◽  
pp. 1413-1417 ◽  
Author(s):  
I. R. Dagg ◽  
A. M. Mue ◽  
G. E. Reesor
Keyword(s):  
Rectangular Cross Section ◽  
Resonant Cavity ◽  
Accurate Method ◽  
Precise Determination ◽  
Q Factor ◽  
Average Temperature ◽  
Wave Measurements ◽  
X Band ◽  
Better Than

A method for the very precise determination of the Q factor of a resonant cavity has been developed. It is based on careful standing-wave measurements taken on a slotted line in front of the cavity over a range of frequencies about the resonant frequency. It is necessary to choose and maintain the frequency to within one or two parts in 109 and to hold the average temperature of the cavity constant to better than 0.001 °C. A large number of readings are taken and the data are processed on an electronic computer. The method has been tested on a reflection-type cavity of rectangular cross section designed for operation in the X band. Reproducibility to within 0.1% has been achieved on successive determinations of Q.

Contactless Mass Determination of Arbitrarily Shaped Objects by Microwave Resonator Measurements

1994 ◽  
Vol 347 ◽  
Author(s):  
Andrzej W. Kraszewski ◽  
Stuart O. Nelson
Keyword(s):  
Uncertainty Analysis ◽  
Resonant Cavity ◽  
Microwave Resonator ◽  
Mass Determination ◽  
Microwave Resonant Cavity ◽  
Dielectric Objects ◽  
Better Than

ABSTRACTThe basis is presented for using a microwave resonant cavity as an effective “contactless balance”, providing information about the mass of dielectric objects inserted into the cavity. An uncertainty analysis presented in the paper confirms that the mass of small dielectric objects can be determined by this technique with an accuracy better than 4%.

scholarly journals A complete study of the precision of the concentric MacLaurin spheroid method to calculate Jupiter’s gravitational moments

2018 ◽  
Vol 609 ◽  
pp. A97 ◽  
Author(s):  
F. Debras ◽  
G. Chabrier
Keyword(s):  
Accurate Method ◽  
Precise Determination ◽  
Observational Constraints ◽  
Perturbative Method ◽  
Density Relationship ◽  
Complete Study ◽  
Fluid Body ◽  
Physical Quantities ◽  
Juno Mission

A few years ago, Hubbard (2012, ApJ, 756, L15; 2013, ApJ, 768, 43) presented an elegant, non-perturbative method, called concentric MacLaurin spheroid (CMS), to calculate with very high accuracy the gravitational moments of a rotating fluid body following a barotropic pressure-density relationship. Having such an accurate method is of great importance for taking full advantage of the Juno mission, and its extremely precise determination of Jupiter gravitational moments, to better constrain the internal structure of the planet. Recently, several authors have applied this method to the Juno mission with 512 spheroids linearly spaced in altitude. We demonstrate in this paper that such calculations lead to errors larger than Juno’s error bars, invalidating the aforederived Jupiter models at the level required by Juno’s precision. We show that, in order to fulfill Juno’s observational constraints, at least 1500 spheroids must be used with a cubic, square or exponential repartition, the most reliable solutions. When using a realistic equation of state instead of a polytrope, we highlight the necessity to properly describe the outermost layers to derive an accurate boundary condition, excluding in particular a zero pressure outer condition. Providing all these constraints are fulfilled, the CMS method can indeed be used to derive Jupiter models within Juno’s present observational constraints. However, we show that the treatment of the outermost layers leads to irreducible errors in the calculation of the gravitational moments and thus on the inferred physical quantities for the planet. We have quantified these errors and evaluated the maximum precision that can be reached with the CMS method in the present and future exploitation of Juno’s data.

Petrus Montanus as a Phonetician and a Theoretician

1988 ◽  
Vol 15 (1-2) ◽  
pp. 85-108 ◽  
Author(s):  
Jos L. M. Hulsker
Keyword(s):  
Spoken Language ◽  
Precise Determination ◽  
The Other ◽  
Speech Sounds ◽  
Object A ◽  
Complete Survey ◽  
Simon Stevin ◽  
Better Than

Summary Petrus Montanus’ (1594/95–1638) book on phonetics, De Spreeckonst (1635), which was intended to apply to all languages, could have been an epoch-making standardwork on phonetics, if it had been read and studied more widely. Although he characterized Spreeckonst as a difficult theory he intended it to be an easy textbook. However, Montanus’ terminology made the book almost unreadable. In the first section special attention is paid to Montanus’ idea that all aspects of his object of inquiry (i.e. the spoken language) had to be characterized as aptly and precisely as possible, after having examined the object (a). Next, (in section 2), an attempt is made to clarify Montanus’ opinion that the precise determination of objects (actually, the result of his scientifc inquiry) should function as a perfect didactic tool for his readers (b). Through names’ the reader could learn to produce speech sounds even better than by simply practising their production. Indeed, Spreeckonst was meant to be both a theory and a practical handbook. This can be explained by pointing out the two functions names had: they were instruments of knowledge (a) and instruments of learning (b). As shown in section 3 Montanus was directly influenced by Simon Stevin (1548–1620) with regard to (b). In section 4 it is shown that, in essence, the first idea (a) can be traced back to Socrates’ ideas on names, as Plato had Socrates defend them in his Cratylus. The other idea (b) can be traced back to Cratylos’ ideas on names, which were unfolded and discussed in the same work. Section 5 analyses the sorts of names Montanus actually used. A complete survey of the names of Montanus’ distinctions of speech sounds is presented in this section. In the concluding section (6) an indication is made of the astonishing results of Montanus’ analyses of spoken language.

scholarly journals Determination of the anisotropic elasticity tensor by mechanical spectroscopy

2021 ◽  
Author(s):  
Thomas Obermayer ◽  
Christian Krempaszky ◽  
Ewald Werner
Keyword(s):  
Base Alloy ◽  
Rectangular Cross Section ◽  
Optimization Method ◽  
Anisotropic Elasticity ◽  
Elasticity Tensor ◽  
Precise Determination ◽  
The Finite Element Method ◽  
Mechanical Spectroscopy ◽  
Nickel Base

AbstractA method is proposed to identify the fully anisotropic elasticity tensor by applying the impulse excitation technique. A specially designed batch of several differently oriented bar-shaped specimens with rectangular cross section is analyzed with respect to the eigenfrequencies of their fundamental flexural and torsional modes. Estimations based on the equations for the calculation of the isotropic Young’s modulus and the shear modulus from the ASTM standard allow a first approximation of the elasticity tensor from a selected subset of the measured eigenfrequencies. Subsequently, a more precise determination of the elasticity tensor is achieved by a numerical modal analysis using the finite element method. In this course, a Newton–Raphson optimization method is applied to solve the inverse problem. The proposed approach is demonstrated on a batch of specimen fabricated from the nickel-base alloy IN718 by selective laser melting.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Usefulness of Foundry Tooling Materials in Microwave Heating Process

2013 ◽  
Vol 58 (3) ◽  
pp. 919-922 ◽  
Author(s):  
K. Granat ◽  
B. Opyd ◽  
D. Nowak ◽  
M. Stachowicz ◽  
G. Jaworski
Keyword(s):  
Electromagnetic Field ◽  
Microwave Heating ◽  
Loss Factor ◽  
Perturbation Technique ◽  
Resonant Cavity ◽  
Precise Determination ◽  
Heating Process ◽  
Basic Criterion ◽  
Measurement Results ◽  
Heating Technology

Abstract The paper describes preliminary examinations on establishing usefulness criteria of foundry tooling materials in the microwave heating technology. Presented are measurement results of permittivity and loss tangent that determine behaviour of the materials in electromagnetic field. The measurements were carried-out in a waveguide resonant cavity that permits precise determination the above-mentioned parameters by perturbation technique. Examined were five different materials designed for use in foundry tooling. Determined was the loss factor that permits evaluating usefulness of materials in microwave heating technology. It was demonstrated that the selected plastics meet the basic criterion that is transparency for electromagnetic radiation.

PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

2010 ◽  
Vol 46 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Yang MENG ◽  
Lin GU ◽  
Wenzheng ZHANG
Keyword(s):  
Precise Determination ◽  
Interface Orientation
Sign in / Sign up

Export Citation Format

Share Document