FDTD Simulation of an Open-Ended Metallized Ceramic Probe for Broadband High-Temperature Dielectric Properties Measurements

1994 ◽  
Vol 347 ◽  
Author(s):  
Shane Bringhurst ◽  
Magdy F. Iskander ◽  
Paul Gartside
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Microwave Sintering ◽  
Fdtd Method ◽  
Fdtd Simulation ◽  
Minimum Thickness ◽  
University Of Utah ◽  
Coaxial Probes ◽  
On Line ◽  
The University

ABSTRACTOpen-ended coaxial probes have been used in broadband dielectric properties measurements for several years. To aid in the ongoing numerical simulation and microwave sintering research at the University of Utah, we have found it necessary to make dielectric properties measurements up to temperatures as high as 1400 °C. The available cavity perturbation techniques were unsuitable in this application due to their relatively narrow band, and the available metal probes are also unsuitable due to the differential thermal expansions of the inner and outer conductors, which makes it difficult to carry out accurate and on-line calibration procedures for these probes.To help us achieve both broadband and high-temperature dielectric properties measurements, we have developed a new metallized ceramic coaxial probe. The detailed design of this probe is described and the metallization procedure is discussed.Also to optimize the design of the probe and in particular to increase the penetration of fields in samples under test and hence improve the probe sensitivity to variation in properties of a larger class of materials, and to determine the required minimum thickness of various samples to obtain accurate results, we modeled and simulated the probe performance using the Finite-Difference Time-Domain (FDTD) method. Results from the FDTD simulation are presented and some guidelines that may be used to optimize the design of the probe are discussed.

High Temperature Broadband Dielectric Properties Measurement Techniques

1992 ◽  
Vol 269 ◽  
Author(s):  
Octavio M. Andrade ◽  
Magdy F. Iskander ◽  
Shane Bringhurst
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Measurement Techniques ◽  
Frequency Range ◽  
University Of Utah ◽  
Microwave Characterization ◽  
Characterization Of Materials ◽  
The University

ABSTRACTThis paper discusses theoretical and practical aspects of the development and implementation of various measurement techniques for high-temperature broadband microwave characterization of materials at the University of Utah. Objectives include materials measurements in the frequency range from 45 MHz to 12 GHz and for temperatures as high as 1000°C.

Development Of A Multi-Grid Fdtd Code For Three-Dimensional Simulation Of Large Microwave Sintering Experiments

1996 ◽  
Vol 430 ◽  
Author(s):  
Mikel J White ◽  
Magdy F. Iskander ◽  
Hal D. Kimrey
Keyword(s):  
Microwave Sintering ◽  
Three Dimensional ◽  
Uniform Grid ◽  
Computer Memory ◽  
University Of Utah ◽  
Grid Codes ◽  
Dimensional Simulation ◽  
The University ◽  
Computer Resources ◽  
Difference Time

AbstractThe Finite-Difference Time-Domain (FDTD) code available at the University of Utah has been used to simulate sintering of ceramics in single and multimode cavities, and many useful results have been reported in literature [1–4]. More detailed and accurate results, specifically around and including the ceramic sample, are often desired to help evaluate the adequacy of the heating procedure. In electrically large multimode cavities, however, computer memory requirements limit the number of the mathematical cells, and the desired resolution is impractical to achieve due to limited computer resources. Therefore, an FDTD algorithm which incorporates multiple-grid regions with variable-grid sizes is required to adequately perform the desired simulations. In this paper we describe the development of a three-dimensional multi-grid FDTD code to help focus a large number of cells around the desired region. Test geometries were solved using a uniform-grid and the developed multi-grid code to help validate the results from the developed code. Results from these comparisons, as well as the results of comparisons between the developed FDTD code and other available variable-grid codes are presented. In addition, results from the simulation of realistic microwave sintering experiments showed improved resolution in critical sites inside the three-dimensional sintering cavity. With the validation of the FDTD code, simulations were performed for electrically large, multimode, microwave sintering cavities to fully demonstrate the advantages of the developed multi-grid FDTD code.

Numerical Simulation and Experimental Validation of RF Drying

1996 ◽  
Vol 430 ◽  
Author(s):  
S. Bringhurst ◽  
M. J White ◽  
M. F. Iskander
Keyword(s):  
Microwave Sintering ◽  
Fdtd Method ◽  
Fdtd Simulation ◽  
Ceramic Ware ◽  
Rf Heating ◽  
Simulation Results ◽  
Effective Use ◽  
Difference Time ◽  
Experimental Effort ◽  
Fiber Optic Temperature

AbstractThe Finite-Difference Time-Domain (FDTD) method has been used by our group to simulate a wide variety of Radio Frequency (RF) and induction-drying processes and realistic, microwave-sintering experiments. Many results were presented and some guidelines towards the effective use of the microwave and RF heating technologies of ceramic ware were developed.In this paper we describe an experimental effort which was used to validate the FDTD simulation results. Specifically an experimental RF dryer, Thermax Model No. T3GB operating at 25 MHz, was used to dry ceramic ware of various materials, sizes, and shapes and the temperature distribution pattern was monitored using six fiber-optic temperature probes. The measured heating patterns were then compared with the FDTD simulation results. Many of the guidelines developed using the numerical simulations were confirmed experimentally.Results from various comparisons between simulation and experimental data will be presented. Additional results from the simulation efforts illustrating possible procedures for improving the efficiency and the uniformity of RF drying will also be described

High Temperature Dielectric Measurements on Ceramics

1992 ◽  
Vol 269 ◽  
Author(s):  
M Aral ◽  
J G P Binner ◽  
G E Carr ◽  
T E Cross
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Alternative Energy ◽  
Elevated Temperatures ◽  
Microwave Dielectric Properties ◽  
Microwave Frequency ◽  
Dielectric Measurements ◽  
Microwave Dielectric ◽  
The University ◽  
Processing Group

ABSTRACTThe use of microwave frequency radiation as an alternative energy source for processing materials is currently receiving considerable worldwide attention. The ability of a material to extract energy from the microwave field depends upon its dielectric properties, however these change as the material heats. There is, therefore, a need for obtaining measurements of the microwave dielectric properties at elevated temperatures. This paper outlines some of the current work on high temperature dielectric measurements which is in progress at the University of Nottingham as part of the Materials and Microwave Processing Group initiative and some results on engineering ceramics are presented.

scholarly journals An On-Line System for High Temperature Dielectric Property Measurement of Microwave-Assisted Sintering Materials

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 665 ◽  
Author(s):  
Li Wu ◽  
Yi Zhang ◽  
Fengxia Wang ◽  
Weiquan Ma ◽  
Tian Xie ◽  
...  
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
High Temperatures ◽  
Dielectric Measurement ◽  
Line System ◽  
Microwave Assisted ◽  
On Line ◽  
Property Measurement ◽  
Properties Of Materials

Microwave-assisted sintering materials have been proven to deliver improvements in the mechanical and physicochemical properties of the materials, compared with conventional sintering methods. Accurate values of dielectric properties of materials under high temperatures are essential for microwave-assisted sintering. In view of this, this paper, proposes an on-line system to measure the high temperature dielectric properties of materials under microwave processing at a frequency of 2450 MHz. A custom-designed ridge waveguide is utilized, where samples are heated and measured simultaneously. An artificial neural network (ANN) trained with the corresponding simulation data is integrated into this system to reverse the permittivity of the measured materials. This whole system is tested at room temperature with different materials. Accuracies of measuring dielectric property with an error lower than 9% with respect to theoretical data have been achieved even for high loss media. The functionality of the dielectric measurement system has also been demonstrated by heating and measuring Macor and Duran ceramic glass samples up to 800 °C. All the preliminary experiments prove the feasibility of this system. It provides another method for dielectric property measurement and improves the understanding of the mechanism between microwave and media under high temperatures, which is helpful for optimizing the microwave-assisted sintering of materials.

scholarly journals Randall's ESL Cyber Listening Lab

2002 ◽  
Vol 1 ◽  
pp. 5
Author(s):  
Rafael Seiz Ortiz
Keyword(s):  
Listening Comprehension ◽  
English Language ◽  
University Of Utah ◽  
Java Programming ◽  
Comprehension Skills ◽  
On Line ◽  
Video And Audio ◽  
English Language Institute ◽  
The University ◽  
Audio Video

<p>Interactive on-line activities to practise and reinforce listening comprehension skills in the English language in diverse formats and study styles. On-line since 1998, the Cyber Listening Lab makes use of Java programming language, and requires video and audio playing software (for example, Real Audio/Video, Divace, Windows Media Player). Plugins, software and files in general are easy to access and download.</p><p>The site is developed and maintained by Randall S. Davis, from the English Language Institute at the University of Utah (USA), and sponsored by Divace Learning Solutions.</p>

Fdtd Simulations And Analysis Of Thin Sample Dielectric Properties Measurements Using Coaxial Probes

1996 ◽  
Vol 430 ◽  
Author(s):  
S. Bringhurst ◽  
M. F. Iskander ◽  
M. J White
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Frequency Band ◽  
Protective Layer ◽  
Alumina Tube ◽  
Nickel Plating ◽  
Thin Sample ◽  
Coaxial Probes ◽  
Fdtd Simulations ◽  
Complete Frequency

AbstractA metallized ceramic probe has been designed for high temperature broadband dielectric properties measurements. The probe was fabricated out of an alumina tube and rod as the outer and inner conductors respectively. The alumina was metallized with a 3 mil layer of moly-manganese and then covered with a 0.5 mil protective layer of nickel plating. The probe has been used to make complex dielectric properties measurements over the complete frequency band from 500 MHz to 3 GHz, and for temperatures as high as 1000 °C.

TEM study of boron additions to cobalt aluminide

1988 ◽  
Vol 46 ◽  
pp. 546-547
Author(s):  
Gerald B. Feldewerth
Keyword(s):  
High Temperature ◽  
Turbine Engines ◽  
Major Drawback ◽  
University Of Missouri ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Wide Range ◽  
Ordered Alloys ◽  
The University ◽  
Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

A Local Area Network for Medical Research; Planning, Realization and Experience

1991 ◽  
Vol 30 (01) ◽  
pp. 53-64 ◽  
Author(s):  
R. Schosser ◽  
C. Weiss ◽  
K. Messmer
Keyword(s):  
Medical Research ◽  
Word Processing ◽  
Local Area Network ◽  
Local Area ◽  
Area Network ◽  
Test Installation ◽  
Cost Performance ◽  
The Public ◽  
On Line ◽  
The University

This report focusses on the planning and realization of an interdisciplinary local area network (LAN) for medical research at the University of Heidelberg. After a detailed requirements analysis, several networks were evaluated by means of a test installation, and a cost-performance analysis was carried out. At present, the LAN connects 45 (IBM-compatible) PCs, several heterogeneous mainframes (IBM, DEC and Siemens) and provides access to the public X.25 network and to wide-area networks for research (EARN, BITNET). The network supports application software that is frequently needed in medical research (word processing, statistics, graphics, literature databases and services, etc.). Compliance with existing “official” (e.g., IEEE 802.3) and “de facto” standards (e.g., PostScript) was considered to be extremely important for the selection of both hardware and software. Customized programs were developed to improve access control, user interface and on-line help. Wide acceptance of the LAN was achieved through extensive education and maintenance facilities, e.g., teaching courses, customized manuals and a hotline service. Since requirements of clinical routine differ substantially from medical research needs, two separate networks (with a gateway in between) are proposed as a solution to optimally satisfy the users’ demands.

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