Density Dependence of High Temperature Dielectric Properties of Debased Alumina and the Effect of a High Loss Additive

1994 ◽  
Vol 347 ◽  
Author(s):  
N. G. Evans ◽  
M. G. Hamlyn
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Density Dependence ◽  
Measurement Technique ◽  
Process Technology ◽  
High Loss ◽  
Property Data ◽  
Powder Samples ◽  
Property Measurement

Research into microwave firing at Staffordshire University has been carried out since 1988 and dielectric property measurements have been used to help in developing process technology. The dielectric property measurement technique (cavity perturbation [1]) is that designed by Atomic Energy of Canada Ltd (A.E.C.L) [2]. The technique was chosen because of it's ability to analyse powder samples as well as solids. In order for dielectric property data to be of use in developing microwave processing, measurements have to be made on the starting materials of the process (i.e powders). When measurements are made on powders it is important to quote the bulk density at which the measurement was made since dielectric properties vary with density as well as frequency and temperature.

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 A Transmission-Based Dielectric Property Probe for Clinical Applications

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3484 ◽  
Author(s):  
Paul Meaney ◽  
Tomas Rydholm ◽  
Helena Brisby
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Measurement Technique ◽  
Clinical Applications ◽  
Clinical Implementation ◽  
Compact Spaces ◽  
Low Profile ◽  
Typical Range ◽  
Initial Results ◽  
Good Agreement

We have developed a transmission-based, open-ended coaxial dielectric probe that can be used in clinical situations and overcomes many of the limitations related to the typical reflection-based dielectric probes. The approach utilizes the low profile, open-ended coaxial cables enabling clinicians to still probe relatively compact spaces. The sensing depth can be extended to as large as 1.5 to 2 cm compared with the more typical range of 0.3 mm for conventional probes and is dramatically less affected by measurement technique variability including poor sample contact and cable bending. As a precursor to an actual clinical implementation, we study the technique in a range of homogeneous liquids with substantially varying dielectric properties. The initial results demonstrate good agreement between the transmission-based probe and commercial, reflection-based probes and pave the way for more substantial clinical implementation.

scholarly journals Development of a Cryogen-Free Compact 3 T Superconducting Magnet for an Electromagnetic Property Measurement System

2021 ◽  
Vol 11 (7) ◽  
pp. 3074
Author(s):  
Jae Young Jang ◽  
Myung Su Kim ◽  
Young Jin Hwang ◽  
Seunghyun Song ◽  
Yojong Choi ◽  
...  
Keyword(s):  
High Temperature ◽  
Measurement System ◽  
Electromagnetic Property ◽  
Superconducting Magnet ◽  
Optimized Design ◽  
Magnet System ◽  
Superconducting Tape ◽  
High Temperature Superconducting ◽  
Target Field ◽  
Property Measurement

A cryogen-free portable 3 T high-temperature superconducting magnet for an electromagnetic property measurement system has been developed to serve as a user facility at the Korea Basic Science Institute. The metallic insulation method was adopted to reduce the charging delay without sacrificing the self-protecting feature. A genetic-algorithm-aided optimized design was carried out to minimize the superconducting tape consumption while satisfying several design constraints. After the design, the compact high-temperature superconducting magnet composed of eight double-pancake coil modules was wound with high-temperature superconducting tape and stainless steel tape, and integrated with a two-stage cryo-cooler. The 3 T magnet was successfully cooled to approximately 20 K with a cryo-cooler and reached the target field of 3 T without any problems. Long-term measurements and a range of other tests were also implemented to verity the performance of the magnet. Test results demonstrated the feasibility of a cryogen-free portable high-temperature superconducting magnet system for electromagnetic property measurement experiments.

scholarly journals Mechanical and Dielectric Properties of Aligned Electrospun Fibers

Fibers ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Blesson Isaac ◽  
Robert M. Taylor ◽  
Kenneth Reifsnider
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Electrospun Nanofibers ◽  
Cold Drawing ◽  
General Interest ◽  
Electrospun Fibers ◽  
Energy Storage Devices ◽  
Electrospinning Technique ◽  
Specific Strength ◽  
Aligned Nanofibers

This review paper examines the current state-of-the-art in fabrication of aligned fibers via electrospinning techniques and the effects of these techniques on the mechanical and dielectric properties of electrospun fibers. Molecular orientation, system configuration to align fibers, and post-drawing treatment, like hot/cold drawing process, contribute to better specific strength and specific stiffness properties of nanofibers. The authors suggest that these improved, aligned nanofibers, when applied in composites, have better mechanical and dielectric properties for many structural and multifunctional applications, including advanced aerospace applications and energy storage devices. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement alone, but not both simultaneously. Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Even though the dielectric property of pure nanofiber mat may not be of general interest, the analysis of the combined effect of mechanical and dielectric properties is relevant to the present analysis of improved and aligned nanofibers. A plethora of nanofibers, in particular, polyacrylonitrile (PAN) electrospun nanofibers, are discussed for their mechanical and dielectric properties. In addition, other types of electrospun nanofibers are explored for their mechanical and dielectric properties. An exploratory study by the author demonstrates the relationship between mechanical and dielectric properties for specimens obtained from a rotating mandrel horizontal setup.

Bone permittivity and its effect on using ground-penetrating radar

Geophysics ◽  
2018 ◽  
Vol 83 (1) ◽  
pp. H1-H11
Author(s):  
Blair B. Schneider ◽  
Georgios Tsoflias ◽  
Don W. Steeples ◽  
Rolfe Mandel ◽  
Jack Hofman
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Ground Penetrating Radar ◽  
Relative Permittivity ◽  
Water Saturation ◽  
Mixing Models ◽  
Bone Properties ◽  
Animal Bone ◽  
Bone Minerals ◽  
Ground Penetrating

Ground-penetrating radar (GPR) is a powerful tool that is still being developed for archaeological investigations. We investigated the dielectric properties of mammoth bone and bone from modern bison, cow, deer, and elk as a proxy for applying GPR for detecting prehistoric animal remains. Sample dielectric properties (relative permittivity, loss factor, and loss-tangent values) were measured with an impedance analyzer over frequencies ranging from 10 MHz to 1 GHz. Bone-sample porosity, bulk density, water saturation, and volumetric water content of the specimens were also measured. The measured sample-relative permittivity values were then compared with modeled relative permittivity values using common dielectric-mixing models to determine which parameters control the best-fit predictions of relative permittivity of animal bone. We observe statistically significant dielectric-property differences among different animal fauna, as well as variation as a function of frequency. In addition, we determine that the relative permittivity values of 8–9 for similar minerals, such as apatite, are not suitable as a proxy for predicting animal bone properties. We estimate new relative permittivity values of 3–5 for dry animal bone minerals in the frequency range of 100–1000 MHz using these common dielectric-mixing models. We postulate that differences in bone microstructure contribute to dielectric-property variability.

Ferroelectric, piezoelectric, and dielectric properties of BiScO3-PbTiO3-Pb(Cd1/3Nb2/3)O3 ternary high temperature piezoelectric ceramics

2013 ◽  
Vol 114 (2) ◽  
pp. 027014 ◽  
Author(s):  
Tian-Long Zhao ◽  
Jianguo Chen ◽  
Chun-Ming Wang ◽  
Yang Yu ◽  
Shuxiang Dong
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Piezoelectric Ceramics

Dielectric Properties of Solid Solutions of BiFeO3 with Pb(Ti, Zr)O3 at High Temperature and High Frequency

1968 ◽  
Vol 39 (1) ◽  
pp. 70-74 ◽  
Author(s):  
Robert T. Smith ◽  
Gary D. Achenbach ◽  
Robert Gerson ◽  
W. J. James
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Solid Solutions ◽  
High Frequency
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