scholarly journals Investigating the Influence of Different Types of Nanoparticles on Thermal and Dielectric Properties of Insulation in Converter Transformer

10.5772/67432 ◽  
2017 ◽  
Author(s):  
Boxue Du
Keyword(s):  
Dielectric Properties ◽  
Different Types

Influence of various multilayer LTCC systems on dielectric properties’ stability in GHz frequency range

2016 ◽  
Vol 33 (3) ◽  
pp. 136-140 ◽  
Author(s):  
Tibor Rovensky ◽  
Alena Pietrikova ◽  
Igor Vehec ◽  
Martin Kmec
Keyword(s):  
Dielectric Properties ◽  
Design Methodology ◽  
Middle Layer ◽  
Ring Resonators ◽  
Frequency Range ◽  
Content Type ◽  
Different Types ◽  
Good Repeatability ◽  
Microstrip Ring ◽  
Multilayer Substrate

Purpose The purpose of this paper is to create multilayer substrate (composite) from various low temperature co-fired ceramic (LTCC) substrates by their mutual combinations and to analyse influence of these multilayer substrates on dielectric properties in GHz frequency range. Design/methodology/approach GreenTape 951, GreenTape 9K7 and Murata LFC were used to create compound multilayer substrates that include three layers: middle layer is from Murata LFC, and both upper and bottom layers are either from GreenTape 951 or GreenTape 9K7. Shrinkage in all x-, y- and z-axes of all substrates including multilayer substrates were analysed, and influence of different shrinkage on dielectric properties was examined by microstrip ring resonators applied on all mentioned of substrates. Findings The middle layer of Murata LFC has significant influence on shrinkage value of composites which has a good repeatability and minimalizes problems with design of multilayer LTCC devices. Impact of middle layer from Murata LFC on dielectric constant is not significant, but on the other hand Q factor (loss tangent) of these composites is increased according to inhomogeneity between single LTCC layers, especially at frequency around 6 GHz. Originality/value The novelty of this work lies in creating multilayers systems from different types of LTCC substrates to find combination with the most suitable physical and dielectric properties for various purposes in GHz range applications.

scholarly journals Finite-element analysis of microwave scattering from a three-dimensional human head model for brain stroke detection

2018 ◽  
Vol 5 (7) ◽  
pp. 180319
Author(s):  
Awais Munawar Qureshi ◽  
Zartasha Mustansar ◽  
Samah Mustafa
Keyword(s):  
Finite Element ◽  
Dielectric Properties ◽  
Electric Field ◽  
Three Dimensional ◽  
Human Head ◽  
Head Model ◽  
Different Types ◽  
Brain Stroke ◽  
Human Head Model ◽  
Brain Stroke Detection

In this paper, a detailed analysis of microwave (MW) scattering from a three-dimensional (3D) anthropomorphic human head model is presented. It is the first time that the finite-element method (FEM) has been deployed to study the MW scattering phenomenon of a 3D realistic head model for brain stroke detection. A major contribution of this paper is to add anatomically more realistic details to the human head model compared with the literature available to date. Using the MRI database, a 3D numerical head model was developed and segmented into 21 different types through a novel tissue-mapping scheme and a mixed-model approach. The heterogeneous and frequency-dispersive dielectric properties were assigned to brain tissues using the same mapping technique. To mimic the simulation set-up, an eight-elements antenna array around the head model was designed using dipole antennae. Two types of brain stroke (haemorrhagic and ischaemic) at various locations inside the head model were then analysed for possible detection and classification. The transmitted and backscattered signals were calculated by finding out the solution of the Helmholtz wave equation in the frequency domain using the FEM. FE mesh convergence analysis for electric field values and comparison between different types of iterative solver were also performed to obtain error-free results in minimal computational time. At the end, specific absorption rate analysis was conducted to examine the ionization effects of MW signals to a 3D human head model. Through computer simulations, it is foreseen that MW imaging may efficiently be exploited to locate and differentiate two types of brain stroke by detecting abnormal tissues’ dielectric properties. A significant contrast between electric field values of the normal and stroke-affected brain tissues was observed at the stroke location. This is a step towards generating MW scattering information for the development of an efficient image reconstruction algorithm.

Improving dielectric properties and thermal conductivity of polymer composites with CaCu3Ti4O12 and β-SiC hybrid fillers

2015 ◽  
Vol 08 (03) ◽  
pp. 1540011 ◽  
Author(s):  
Xin Ouyang ◽  
Peng Cao ◽  
Weijun Zhang ◽  
Zhaohui Huang ◽  
Wei Gao
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Response ◽  
Interfacial Polarization ◽  
Melt Blending ◽  
Hybrid Fillers ◽  
Different Types ◽  
Thermally Conductive ◽  
Sic Whiskers

In this paper, we report a series of homogeneous polymeric composites with enhanced dielectric properties and thermal conductivity. The composites were constituted of polyvinylidene fluorides (PVDFs) matrix and CaCu 3 Ti 4 O 12 (CCTO) monolithic or CCTO/β- SiC hybrid fillers, and prepared by simple melt blending and hot moulding technique. The influence of different types of fillers and their composition on the dielectric response and thermal conductivity of the obtained composites was studied. Results show that hybrid loading is preferred and a reasonable combination of thermal conductivity (0.80 W⋅m-1⋅K-1), dielectric constant (∼50) and dielectric loss (∼0.07) at 103 Hz was achieved in the PVDF composite containing 40 vol.% CCTO and 10 vol.% β- SiC . The strong dipolar and interfacial polarization derived from the fillers are responsible for the enhancement of the dielectric constant, while the formation of thermally conductive networks/chains by β- SiC whiskers contributes to the improved thermal conductivity.

scholarly journals Influence of magnetic nanoparticles on dielectric properties of Shell oil transformer oil

2021 ◽  
Vol 24 (02) ◽  
pp. 154-159
Author(s):  
O.V. Kovalchuk ◽  
◽  
O.B. Nesterenko ◽  
V.Yo. Kotovskyi ◽  
I.P. Studenyak ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Low Frequency ◽  
Transformer Oil ◽  
Magnetic Impurities ◽  
Different Types

The influence of two types of nano-impurities MF1 and MF2 on the dielectric properties of Shell oil transformer oil at the temperature 293 K has been studied. It has been shown that these magnetic impurities have no significant effect on the dielectric permittivity value of Shell oil, but more significantly increase its conductivity, in so doing, the impurity MF1 increases the conductivity of transformer oil 4 times larger than the impurity MF2. It has been ascertained that the low-frequency dielectric relaxation appearing in the studied samples can be described by the Cole–Cole equation. The parameters of this relaxation process and the influence of different types of magnetic impurities on them have been estimated.

Theory of Dielectric Properties of Heterogeneous Substances Applied to Water in a Paint Film

CORROSION ◽  
1985 ◽  
Vol 41 (2) ◽  
pp. 69-75 ◽  
Author(s):  
S. A. Lindqvist
Keyword(s):  
Dielectric Properties ◽  
Linseed Oil ◽  
Steel Substrate ◽  
Paint Film ◽  
Poor Correlation ◽  
Empirical Expression ◽  
Practical Applications ◽  
Different Types ◽  
Red Lead ◽  
The Difference

Abstract The water content of 12 paints on steel substrate, exposed to 0.1M sodium chloride at 25 C for 24 h, was calculated from impedance measurements and compared with gravimetric determinations. Brasher's empirical expression was compared with five mixture formulas derived from the theory of dielectric properties of heterogeneous substances by Boettcher, Bruggeman, Looyenga, Wagner, and Rayleigh. The 12 paints were based on two grades of red lead and iron oxide in epoxy, chlorinated rubber, alkyd, and linseed oil binders. The significance of the results for cyclic wet/dry paint tests according to (1) the difference between the water absorption and desorption rates of a single paint and (2) the testing of different types of paints in the same cycle test program are exemplified. A possible explanation is given for the poor correlation often found between the results of cyclic wet/dry tests and those obtained in practical applications.

The extinction time of a general birth and death process with catastrophes

1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell
Keyword(s):  
Laplace Transform ◽  
Size Distribution ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Death Process ◽  
Extinction Time ◽  
Birth And Death Process ◽  
Different Types ◽  
The Laplace Transform ◽  
Necessary And Sufficient

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.

Differentiating between different forms of moral obligations

2020 ◽  
Vol 43 ◽  
Author(s):  
Rajen A. Anderson ◽  
Benjamin C. Ruisch ◽  
David A. Pizarro
Keyword(s):  
Moral Character ◽  
Moral Obligations ◽  
Different Types

Abstract We argue that Tomasello's account overlooks important psychological distinctions between how humans judge different types of moral obligations, such as prescriptive obligations (i.e., what one should do) and proscriptive obligations (i.e., what one should not do). Specifically, evaluating these different types of obligations rests on different psychological inputs and has distinct downstream consequences for judgments of moral character.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

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