The Influence Factors of Wood Dielectric Constant

2012 ◽  
Vol 461 ◽  
pp. 779-782
Author(s):  
Xiang Ling Zhang ◽  
Ying Chun Cai ◽  
Qiao Fang Zhou ◽  
Jing Yao Zhao
Keyword(s):  
Dielectric Constant ◽  
Influence Factors ◽  
Longitudinal Direction ◽  
Tangential Direction ◽  
Dielectric Constants ◽  
Exponential Relationship ◽  
Change Trend ◽  
The Difference ◽  
The Relationship ◽  
Frequency Heating

Dielectric constants of Larix gmelinii were measured at 1.1 MHz to 25 MHz (near to frequency of high-frequency heating ), from oven-drying condition to 100％ moisture content, with longitudinal, radial and tangential directions measuring in the experiment. The results showed that: the relationship between MC and dielectric constant can be described as exponential relationship from MC=8% to the fiber saturation point (FSP), above FSP it is linear relationship. The dielectric constant showed decreasing trends when frequency raised. When f﹥10MHz change trend is slow. Permittivity across longitudinal direction is bigger than that across transverse direction，but the difference across tangential direction and that across radial direction is small.

B-O Bond Character and Microwave Dielectric Properties of (1-x)CaTiO3-xCa(Zn1/3Nb2/3)O3 Perovskite Ceramics

2009 ◽  
Vol 421-422 ◽  
pp. 69-72
Author(s):  
Jie Shen ◽  
Wen Chen ◽  
Jing Zhou ◽  
Jie Zhu ◽  
Qiong Lei
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Dielectric Materials ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Identical Result ◽  
Microwave Dielectric ◽  
Calculation Results ◽  
The Relationship

The relationship between the character of the B-site cation–oxygen bond and the microwave dielectric properties in perovskites dielectric materials was studied in this paper. The atomic net charge of CaTiO3 (CT) and Ca(Zn1/3Nb2/3)O3 (CZN) was calculated respectively. The calculating result implies that the covalency of B-O bonds in CZN is stronger than that in CT. This predicted that the dielectric constant and loss of the ceramics will decrease after CZN incorporated in CT. To confirme the prediction, (1-x)CT-xCZN microwave dielectric ceramics were prepared by solid state reaction method with ZnNb2O6 as precursor. The structure analysis in terms of tolerance factor gives an identical result as calculation. The microwave dielectric properties, such as dielectric constants, Q×f values and τf were studied as a function of composition. With x increasing from 0.2 to 0.8, the dielectric constant linearly decreases from 109 to 49.37, the Q×f value increases from 8,340 to 13,200 GHz, and τf decreases from 321 to -18 ppm/°C. The properties trends are consistent with the previous calculation results, and confirm the relationship between the character of B-O bond and dielectric properties.

scholarly journals Experimental Determination of TDR Calibration Relationship for Pyroclastic Ashes of Campania (Italy)

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3727 ◽  
Author(s):  
Giovanna Capparelli ◽  
Gennaro Spolverino ◽  
Roberto Greco
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Organic Matter Content ◽  
Free Water ◽  
Time Domain Reflectometry ◽  
Dielectric Constants ◽  
Phase System ◽  
Three Phase ◽  
The Relationship

Time domain reflectometry (TDR) is one of the most widely used techniques for indirect determination of soil volumetric water content (θ). TDR measures the relative dielectric constant (εr) which, in a three-phase system like the soil, depends on water, air, and solid matrix dielectric constants. Since dielectric constant of water is much larger than the other two, εr of bulk soil mainly depends on water content. In many cases, the application of TDR requires a specific calibration of the relationship θ(εr) to get quantitatively accurate estimates of soil water content. In fact, the relationship θ(εr) is influenced by various soil properties, such as clay content, organic matter content, bulk density, and aggregation. Numerous studies have shown that pyroclastic soils often exhibit a peculiar dielectric behavior. In Campania (Southern Italy) wide mountainous areas are covered by layered pyroclastic deposits of ashes (loamy sands) and pumices (sandy gravels), often involved in the triggering of landslides induced by rainwater infiltration. Reliable field measurements of water content of such soils are therefore important for the assessment of landslide risk. Hence, in this paper, the θ(εr) relationship has been experimentally determined on samples of typical pyroclastic soil of Campania, collected around Sarno, reconstituted with different porosities. The aim of the study is to identify specific calibration relationships for such soils based not only on empirical approaches. In this respect, a three-phase dielectric mixing model with a variable exponent is introduced, and the variable value of the exponent is related to the different dielectric properties of bond and free water within the soil pores.

Characteristics of 2D Cylindrical Photonic Crystals Band Gap with Square Lattice

2013 ◽  
Vol 712-715 ◽  
pp. 302-305
Author(s):  
Zhao Xia Wu ◽  
Wen Chao Li ◽  
Er Dan Gu ◽  
Li Fu Wang
Keyword(s):  
Dielectric Constant ◽  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Fdtd Method ◽  
Dielectric Constants ◽  
Square Lattice ◽  
The Difference ◽  
Difference Time ◽  
Photonic Band

The structure of two-dimensional (2D) photonic crystals (PCs) with square lattice is proposed in this paper, and researches on characteristics of photonic band gap (PBG) are conducted using finite difference time domain (FDTD) method, then the effects of the dielectric constant and the radius of dielectric rods on band gap are analysed, dielectric rods in air (rods/air). The research results indicate that in the case of TE and TM polarization mode, the difference value of dielectric constant of medium and dielectric rods affects forming PBG.The band gap broadens with the difference value increasing. Whats more, the complete band gap (CBG) appears in range of large rods radius structure when dielectric constants of rods are smaller than that of medium.

Theoretical exploration of factors affecting dielectric constants of masson pine

Holzforschung ◽  
2004 ◽  
Vol 58 (4) ◽  
pp. 418-422 ◽  
Author(s):  
Z.-Q. Hou ◽  
Z. Chen ◽  
R.S. Wright
Keyword(s):  
Dielectric Constant ◽  
Moisture Content ◽  
Volume Fraction ◽  
Density Ratio ◽  
Longitudinal Direction ◽  
Pinus Massoniana ◽  
Dielectric Constants ◽  
Masson Pine ◽  
Factors Affecting ◽  
Ray Cells

AbstractA theoretical model to calculate the dielectric constant of masson pine (Pinus massoniana) in the longitudinal direction was developed by considering the effect of wood moisture content, density, ratio of earlywood to latewood, and the volume fraction of ray cells. The calculated results were used to explore the relationship between dielectric constant and moisture content, density, and other factors. The results indicated that the dielectric constant of masson pine increased with the moisture content. From 0% to 30% moisture content, the longitudinal dielectric constant increased more than 5 times from 2.3 to 13.3. In the range of density from 0.450 to 0.650 (g cm−3at 15% moisture content, the longitudinal dielectric constant increased from 7.7 to 10.0. However, the longitudinal dielectric constant decreased as the volume fraction of ray cells increased.

scholarly journals Tfet Biosensor Simulation and Analysis for Various Biomolecules

2021 ◽  
Author(s):  
P Vimala ◽  
Likith Krishna L ◽  
Sharma SS ◽  
Rakshanda Ainapur ◽  
Swetha RH
Keyword(s):  
Dielectric Constant ◽  
Energy Band Diagram ◽  
Drain Current ◽  
Dielectric Constants ◽  
Device Structure ◽  
Current Variation ◽  
Effect Transistor ◽  
The Difference ◽  
And Performance ◽  
Silvaco Atlas

Abstract This paper investigates the simulation and performance of Tunnel field effect transistor (TFET) with a nanocavity in it, which can be used for bio sensing application. The entire simulation is done using the tool Silvaco Atlas TCAD. This paper mainly aims in comparing the different parameters for few biomolecules which has different dielectric constant values, namely Streptavidin, Biotin, APTES, Cellulose and DNA. The device structure here consists of a nanocavity near the source end, which is used to place these biomolecules and hence observe the variation of the Drain current v/s Gate voltage characteristic graph, these biomolecules that are having unique dielectric constants are placed within this cavity and these graphs are observed. The energy band diagram of this device is obtained; on top of this various other parameters namely Surface Potential, Electric field are observed for the above-mentioned Biomolecules. The Length of the cavity of the biosensor is also varied to observe the difference, in addition to this Ion (ON current) variation is plotted for the change in the dielectric constant of the biomolecule.

Temperature dependence of dielectric properties of some wood species at low frequency range

2011 ◽  
Vol 1 (2) ◽  
pp. 73-76
Author(s):  
V.B. Marella ◽  
R. Jeevan Kumar ◽  
Adeel Ahmad
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Wood Species ◽  
Low Frequency ◽  
Tectona Grandis ◽  
Tangential Direction ◽  
Dielectric Constants ◽  
Effect Of Temperature ◽  
Dielectric Parameters

The effect of temperature on the dielectric properties of some wood species such as Kadam ( Haldina cordifolia), Teak (Tectona grandis L) and Sal tree (Shorea robusta)) wood were investigated at different frequencies from 100Hz to 1MHz along tangential direction. Dielectric constants and dielectric loss factors were measured at temperatures from 30o C to 120°C with variation of frequency showing increase in dielectric constant and dielectric loss with the increase of temperature. Dielectric properties on wood showed a strong relation dependence on the structures, water‐wood relations, frequency and temperature. A significant variation in dielectric parameters was observed with respect to each species. An abrupt increase in dielectric constant was observed when frequency was less than 1 kHz. The variation in activation energy is observed from one species to other.

Flexible Ceramic-Polymer Composite Substrates with Spatially Variable Dielectrics for Miniaturized RF Applications

2009 ◽  
Vol 1161 ◽  
Author(s):  
Zuhal Tasdemir ◽  
Gullu Kiziltas
Keyword(s):  
Dielectric Constant ◽  
Tape Casting ◽  
Composite Films ◽  
Spatial Arrangement ◽  
Ceramic Composites ◽  
Dielectric Constants ◽  
Novel Material ◽  
The Difference ◽  
High Dielectric ◽  
Tape Cast

AbstractThe goal of this research is to develop a process suitable for producing monolithic conformal substrates with a spatial arrangement of material cells according to a particular design creating novel material systems, useful for many multi- functional electronic and Radio Frequency devices. In this study, MCT ceramics (Mg-Ca-Ti-O systems) and organic binders (polymer solution) are mixed and fabricated as films through a process called tape casting to compromise between high dielectric constant and flexibility. Prior to optimizing the process, several characterization studies are carried out: Commercial spray dried MCT powders (Transtech Inc.) with dielectric constant k=70 and k=20 were analyzed as pressed and produced into tape cast films. Dielectric properties are then measured by an Agilent 16451B material analysis kit and their microscopic behavior is examined by scanning electron microscopy. Results show that flexible composite films show a maximum dielectric constant of ε∼22 unlike their powder pressed form with ε ∼16 but their loss behavior deteriorates when compared with their sintered form and a loss tangent factor of 0.001. The difference is attributed to the air content vs. polymer presence of the material in powder pressed form. Also, these substrates naturally are no longer flexible; hence studies are focused on their tape cast form. The potential of these dielectric shades to serve as candidate constituents for producing monolithic textured polymer-ceramic-composites with controllable loss is studied further. Four properties are of prime importance: tunability of dielectric constants to achieve miniaturization, flexibility via low temperature processing of polymers and loss controllability.

Comparison of In-the-Ear and Over-the-Ear Hearing Aid Fittings

1986 ◽  
Vol 51 (4) ◽  
pp. 362-369 ◽  
Author(s):  
Donna M. Risberg ◽  
Robyn M. Cox
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Comparative Evaluation ◽  
Speech Intelligibility ◽  
Hearing Aid ◽  
Hearing Aid Fitting ◽  
The Difference ◽  
Functional Gain ◽  
The Relationship

A custom in-the-ear (ITE) hearing aid fitting was compared to two over-the-ear (OTE) hearing aid fittings for each of 9 subjects with mild to moderately severe hearing losses. Speech intelligibility via the three instruments was compared using the Speech Intelligibility Rating (SIR) test. The relationship between functional gain and coupler gain was compared for the ITE and the higher rated OTE instruments. The difference in input received at the microphone locations of the two types of hearing aids was measured for 10 different subjects and compared to the functional gain data. It was concluded that (a) for persons with mild to moderately severe hearing losses, appropriately adjusted custom ITE fittings typically yield speech intelligibility that is equal to the better OTE fitting identified in a comparative evaluation; and (b) gain prescriptions for ITE hearing aids should be adjusted to account for the high-frequency emphasis associated with in-the-concha microphone placement.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

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