Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 47 for “"dielectric loss"”.
-
Dielectric loss determination using perturbation
A dielectric filled cavity structure is currently being used to estimate the dielectric constant and loss factor over a wide range of frequencies of a dielectric material which fills the cavity structure [Saed, 1987]. A full field analysis is used to compute the effective complex permittivity of …
-
Simulation of Microwave Heating of Mullite Rods
… of the strong temperature dependence of the dielectric loss. The ability of a ceramic to absorb microwave energy, a measure of its dielectric loss, increases with temperature which makes the material more susceptible to thermal runaway. The purpose of this research is to develop a model that …
-
Numerical Simulation of Microwave Sintering of Zinc Oxide
… by the irregular temperature dependence of the dielectric properties of zinc oxide, particularly dielectric loss. Two thermocouple probes were used to measure the temperature response in a small cylindrical sample of zinc oxide packed in powder insulation, and heated in a microwave oven. In …
-
3-D temperature distributions in spot heating of a ceramic by a focused microwave source
… method. Using experimentally measured dielectric loss properties for alumina, the required electric field strengths to raise the temperature of a localized spot in a rectangular block to 1500K are presented. With the block moving on an insulating support, the results also show that …
-
A coupled electromagnetic and heat transfer finite-element model for simulating microwave processing of composite materials in a cylindrical resonant cavity
… generation in the process material is due to dielectric loss in the material and is related to the dielectric loss factor ofthe material, the processing frequency, and the magnitude of the electric field. The finite-element method was used to develop both the electromagnetic and heat transfer …
-
Dielectric Properties of lce
A laboratory study of the dielectric behaviour of single crystals of ice from a temperate glacier and ice cores from the Greenland ice cap is described. A field investigation of the properties of snow on Axel Heiberg Island (Arctic Canada) is discussed. The permittivity of ice in the HF and VHF …
-
Synthesis of Multifunctional One-dimensional and Two-dimensional Highly Conductive Nanomaterials for Charge Storage Applications
… (PMMA) to fabricate a high performance dielectric material. To improve the dielectric performance of the nanocomposites, a hybrid structure, containing AgNW and MnO2NW, was utilized to not only enhance the dielectric constant but also minimize the dielectric loss. The fabricated …
-
Optimization of Polymer-based Nanocomposites for High Energy Density Applications
… lightweight and compact high energy density dielectrics. This limitation in performance is due to the trade-off between dielectric constant and dielectric breakdown. Insulating polymers are of interest owing to their high inherent electrical resistance, low dielectric loss, flexibility, light …
-
Electromagnetic radiation calorimetry of thermoplastics, elastomers and composites systems
… Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and …
-
Attenuation of electromagnetic radiation by water droplets in the atmosphere
… frequency. (2) Absorption - it is found that the dielectric loss is much greater than the conductivity loss in the frequency range 10 M Hz. to 300 M Hz. The absorbed power is found to be much greater than the scattered power in the frequency range 10 M Hz. to 300 M Hz. Multiple scattering is …
-
The effects of crosslinking byproducts on the electrical properties of low density polyethylene
… byproducts on space charge formation, dielectric properties, dc conductivity as well as the ac breakdown strength. Percentage weight increases as well as the Fourier Transform Infrared (FTIR) spectrum were used to monitor the chemical level in the soaked samples. Despite high …
-
Fundamental experiments on the response of solutions, polymers, and modified polymeric materials to electromagnetic radiation
… divided into two sections. In the first section dielectric and magnetic properties were analyzed for a series of materials: bisphenol A solutions, a poly(amideimide), and polymers filled with either carbon black, iron particles, or aluminum flake. The second section deals with the influence of …
-
Experimental Verification for Microwave Processing of Materials in a Single Mode Rectangular Resonant Cavity
… due in part to the temperature dependence of the dielectric loss of many industrial materials such as ceramics and polymers. These materials absorb more microwave energy as they heat, creating uncontrollable heating, often called 'thermal runaway'. The focus of this research is to address this …
-
Large-Signal Characterization of Piezoelectric Resonators for Power Conversion
… data to more completely characterize the losses in piezoelectric resonators owing to both mechanical and dielectric effects. To account for mechanical losses, the variation in resonator quality factor is examined across a range of drive levels for multiple resonator sizes, frequencies, and …
-
Magnetic and Dielectric Properties of Cu3-xNixWO6 and Cu3W1-xMoxO6
… with the increasing concentration of Ni. The dielectric permittivity as a function of temperature and different frequency from1 kHz to 20 kHz for all samples, were investigated. A peak in dielectric loss ε'' appears between 150 K to 260 K in all samples of Cu3-xNixWO6. The peak position has a …
-
Ceramic dielectrics for high energy density capacity application
… electrical properties of titanium oxide (TiO₂) dielectrics for high energy density capacitor applications. The effects of aliovalent dopants on the dielectric properties of TiO₂ ceramics were investigated, aiming to further improve the desired dielectric properties especially at elevated …
-
Measuring Characteristic Shrinkage Variability Due to Metal Loading Effects in Low Temperature Co-Fired Ceramic Using Image Processing
… it comes to electronic packaging due to the low dielectric loss, reliability in extreme environments, and high breakdown voltage. Though the ceramic has a lot of benefits it is not widely used due to the high cost and complexities associated with manufacturing. One of these issues with …
-
Characterization of MnZn ferrite materials and finite element method for MnZn ferrite core loss calculations
… work presents the method of calculating the core loss in ferrite cores by using a linear and sinusoidal finite element solver based on the material property data (the complex permeability, the dielectric constant, and the AC conductivity) measured in the laboratory. Due to the lack of published …
-
Biofidelic Piezoresistive Sandwich Composites
… of silicone and CNT sheet, comprising two dielectric facesheets and a highly conductive core layer has added advantages of raising the dielectric permittivity and suppressing dielectric loss.</p> <p>In this thesis, a fabrication methodology was developed for a proprietary blend of two-part …
-
Ionic Mobility In Stuffed-Silica Minerals
Using a combination of dielectric spectroscopy and atomistic computer simulation techniques, the dynamical behaviour of loosely bound cations in the stuffed-silica minerals nepheline, yoshiokaite and ß-eucryptite has been investigated. The investigation has been extended to include the feldspar …
Page 1 of 3