Dimensional Effects on the Measurement of Permittivity of Semiconducting Materials Used in High Voltage XLPE Cables

2008 ◽  
Vol 9 (1) ◽  
Author(s):  
Juan Juan Yang ◽  
Da Ming Zhang
Keyword(s):  
High Voltage ◽  
Partial Discharge ◽  
Semiconducting Materials ◽  
Dimensional Effect ◽  
Semiconducting Material ◽  
Dimensional Effects ◽  
Different Dimensions ◽  
The Difference ◽  
Materials Used ◽  
Set Up

The intrinsic permittivity, not apparent permittivity, of semiconducting layers of high voltage cross-linked polyethylene (XLPE) cables imposes a significant influence on the design of partial discharge detecting sensors. It has extremely high permittivity, resulting in a dimensional effect, an embodiment of the difference between the intrinsic permittivity and apparent or measurable permittivity. To investigate this dimensional effect in semiconducting material, a mathematical model is set up in this paper for a capacitor with two rectangular-shaped electrodes in parallel, between which is inserted a semi-conducting sample. First, the expression of the electric field in the semiconducting material is worked out theoretically. Then, the measurable or apparent complex permittivity is expressed as a function of intrinsic permittivity, dimensions of the sample and frequency. Next, five blocks with different dimensions are introduced to study the dimensional effect. The numerical analysis demonstrates that above 10 MHz, samples with different dimensions result in different apparent permittivity or measurable permittivity if experiments are carried out for the samples with the assumed dimensions. This implies that dimensional effects should be considered when accurate intrinsic permittivity of the semiconducting materials is needed.

Growth and yield of okra (Abelmoschus esculentus (L.) Moench) grown in the marginal upland area of Sta. Rita, Samar as influenced by different planting densities and mulching materials

2017 ◽  
pp. 44-54
Author(s):  
Zenaida Gonzaga ◽  
Warren Obeda ◽  
Ana Linda Gorme ◽  
Jessie Rom ◽  
Oscar Abrantes ◽  
...  
Keyword(s):  
Bare Soil ◽  
Abelmoschus Esculentus ◽  
Growth And Yield ◽  
Planting Density ◽  
Rice Hull ◽  
Plastic Mulch ◽  
Lady’S Finger ◽  
Materials Used ◽  
Set Up ◽  
A Minor

Okra or Lady’s finger, botanically known as Abelmoschus esculentus (L.) Moench, is a tropical and sub-tropical indigenous vegetable crop commonly grown for its fibrous, slimy, and nutritious fruits and consumed by all classes of population. It has also several medicinal and economic values. Despite its many uses and potential value, its importance is under estimated, under-utilized, and considered a minor crop and little attention was paid to its improvement. The study was conducted to evaluate the effects of different planting densities and mulching materials on the growth and yield of okra grown in slightly sloping area in the marginal uplands in Sta. Rita, Samar, Philippines. A split-plot experiment was set up with planting density as main plot and the different mulching materials as the sub-plot which were: unmulched or bare soil, rice straw, rice hull, hagonoy and plastic mulch. Planting density did not significantly affect the growth and yield of okra. Regardless ofthe mulching materials used, mulched plants were taller and yielded higher compared to unmulched plants. Moreover, the use of plastic mulch resulted to the highest total fruit yield. The results indicate the potential of mulching in increasing yield and thus profitability of okra production under marginal upland conditions.

scholarly journals The Pandemic and Changes in the Self-Perception of Teacher Digital Competences of Infant Grade Students: A Cross Sectional Study

2021 ◽  
Vol 18 (9) ◽  
pp. 4756
Author(s):  
Rosalía Romero-Tena ◽  
Carmen Llorente-Cejudo ◽  
María Puig-Gutiérrez ◽  
Raquel Barragán-Sánchez
Keyword(s):  
Intervention Group ◽  
Cross Sectional Study ◽  
Self Perception ◽  
Digital Competence ◽  
Cross Sectional ◽  
Self Perceptions ◽  
Group A ◽  
Different Dimensions ◽  
The Difference ◽  
Group B

Without having a reaction time, the pandemic has caused an unprecedented transformation in universities around the world, leading to a revolution from structured models anchored in the conception of transmission of training towards a teaching approach-learning saved thanks to the incorporation of technology. This study aims to verify whether the pandemic situation has influenced the digital competence self-perception of students. Comparing two groups during the academic years 2019/2020 and 2020/2021, the instrument used is the questionnaire for digital competence “DigCompEdu Check-In” for future teachers. After the educational intervention, group A (before COVID-19) presented higher self-perceptions of competence than group B (during COVID-19); the pandemic situation caused by COVID-19 has negatively influenced students’ self-perception of their digital skills in the pretest in the different dimensions under study. Before receiving the training, the group that did not experience the pandemic enjoyed a higher self-perception of their competencies than the group that experienced the pandemic. The data obtained indicate that the difference exists, and that it is statistically significant, and may be a consequence of the clear relationship between self-perception and the way in which students face reality through their personal and subjective vision.

Experimental Investigation into Driver Behavior along Curved and Parallel Diverging Terminals of Exit Interchange Ramps

2021 ◽  
pp. 036119812199742
Author(s):  
Alberto Portera ◽  
Marco Bassani
Keyword(s):  
Design Stage ◽  
Lane Change ◽  
Age And Gender ◽  
Traffic Conditions ◽  
Current Design ◽  
The Difference ◽  
Safety Countermeasures ◽  
And Gender ◽  
Set Up ◽  
Curve Radius

Current design manuals provide guidance on how to design exit ramps to facilitate driving operations and minimize the incidence of crashes. They also suggest that interchanges should be built along straight roadway sections. These criteria may prove ineffective in situations where there is no alternative to terminals being located along curved motorway segments. The paper investigates driving behavior along parallel deceleration curved terminals, with attention paid to the difference in impact between terminals having a curvature which is the same sign as the motorway segment (i.e., continue design), and those having an opposite curvature (i.e., reverse design). A driving simulation study was set up to collect longitudinal and transversal driver behavioral data in response to experimental factor variations. Forty-eight drivers were stratified on the basis of age and gender, and asked to drive along three randomly assigned circuits with off-ramps obtained by combining experimental factors such as motorway mainline curve radius (2 values), terminal length (3), curve direction (2), and traffic conditions (2). The motorway radius was found to be significant for drivers’ preferred speed when approaching the terminal. Terminal length and traffic volume do not have a significant impact on either longitudinal or transversal driver outputs. However, the effect of curve direction was found to be significant, notably for reverse terminals which do not compel drivers to select appropriate speeds and lane change positions. This terminal type can give rise to critical driving situations that should be considered at the design stage to facilitate the adoption of appropriate safety countermeasures.

Study on the strength of glued laminated timber beams with round holes: difference in structural performance between homogeneous-grade and heterogeneous-grade timber

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Shigefumi Okamoto ◽  
Nobuhiko Akiyama ◽  
Yasuhiro Araki ◽  
Kenji Aoki ◽  
Masahiro Inayama
Keyword(s):  
Scots Pine ◽  
Maximum Shear Stress ◽  
Material Strength ◽  
Laminated Beams ◽  
Strength Grade ◽  
Glued Laminated Timber ◽  
The Difference ◽  
Materials Used ◽  
Beam Height ◽  
Timber Beams

AbstractVarious design codes and design proposals have been proposed for glued laminated timber beams with round holes, assuming that the entire beam is composed of homogeneous-grade timber. However, in Japan, glued laminated timber composed of homogeneous-grade timber is rarely used for beams. In this study, the difference in the load-bearing capacity of glued laminated beams composed of homogeneous-grade timber and heterogeneous-grade timber with round holes when fractured by cracking was investigated experimentally and analytically. The materials used in the tests were glued laminated beams composed of homogeneous-grade Scots pine timber with a strength grade of E105-F345 and heterogeneous-grade Scots pine timber with a strength grade of E105-F300. Experiments confirmed that although the glued laminated beams composed of heterogeneous-grade timber have a lower material strength in the lamina with holes, its resistance to fracturing due to cracks associated with the holes is almost the same as that of the glued laminated beams composed of homogeneous-grade timber. The stresses acting on the holes in the laminated timber with holes of less than half the beam height were lower in the glued laminated beams composed of heterogeneous-grade timber than in the glued laminated beams composed of homogeneous-grade timber. The ratio of the stresses was found to be approximately equal to the ratio of the maximum bending stress or the maximum shear stress acting on the inner layer lamina, as determined by Bernoulli–Euler theory.

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