scholarly journals A Study on the Life Estimation and Cavity Surface Degradation Due to Partial Discharges in Spherical Cavities within Solid Polymeric Dielectrics Using a Simulation Based Approach

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 324
Author(s):  
Johnatan M. Rodríguez-Serna ◽  
Ricardo Albarracín-Sánchez
Keyword(s):  
Ultra Violet ◽  
Polymeric Materials ◽  
Damage Function ◽  
Point Of View ◽  
Partial Discharges ◽  
Cavity Surface ◽  
Simulation Based ◽  
Ageing Rate ◽  
Solid Dielectrics ◽  
Polymeric Solid

Partial Discharges (PD) in cavities are responsible for the greatest ageing rate in polymeric solid dielectrics due to chemical and physical deterioration mechanisms activated by the charge carriers, Ultra Violet (UV) radiation and local temperature rising during PDs activity. From the above, it is necessary to develop prognosis tools based on PDs measurements as diagnostic quantities in order to infer the time-to-breakdown, life, of solid dielectrics for improving the reliability of electrical assets, especially in current applications where they are subject to great electrical stresses in voltage frequency and magnitude. In this paper, the degradation in polymeric materials induced by PDs in cavities is briefly discussed from a phenomenological point of view, and then it is quantitatively evaluated using a simulation-based approach and a new proposed damage function. The time-to-breakdown calculated from simulations exhibits good agreement when compared with experimental measurements. Additionally, an analysis on the effect of the magnitude and frequency of the applied voltage on the degradation rate is also presented and the effectiveness of a degradation indicator, proposed by other authors, is evaluated under different stress conditions.

scholarly journals Numerical Simulation of Temperature and Pressure Changes due to Partial Discharges in Spherical Cavities Within Solid Dielectrics at Different Ageing Conditions

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4771 ◽  
Author(s):  
Johnatan M. Rodríguez-Serna ◽  
Ricardo Albarracín-Sánchez
Keyword(s):  
Dielectric Material ◽  
Surface Condition ◽  
Partial Discharges ◽  
Cavity Surface ◽  
Element Analysis ◽  
Finite Element Analysis Simulation ◽  
Insulation Systems ◽  
Temperature And Pressure ◽  
Solid Dielectrics ◽  
Pressure Changes

Partial Discharges (PD) behavior during ageing of the insulation systems exhibits variations that depend on changes in gas filling characteristics and surface condition. In this article, numerical simulations of temperature and pressure behavior in an air-filled spherical cavity within a homogenous solid dielectric material due to PD activity are presented. An Analytical-Finite Element Analysis simulation approach was implemented in MATLAB and results exhibit reasonable agreement with experimental measurements reported by other authors. Simulation results allow concluding that pressure changes are directly related to variations in the PD behavior. In addition, affectations to cavity surface due to temperature increments can be discarded.

Adjustable wetting of Liquid Flame Spray (LFS) TiO2-nanoparticle coated board: Batch-type versus roll-to-roll stimulation methods

2014 ◽  
Vol 29 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Mikko Tuominen ◽  
Hannu Teisala ◽  
Janne Haapanen ◽  
Mikko Aromaa ◽  
Jyrki M. Mäkelä ◽  
...  
Keyword(s):  
Argon Plasma ◽  
Ultra Violet ◽  
High Volume ◽  
Point Of View ◽  
Flame Spray ◽  
Ambient Conditions ◽  
Batch Type ◽  
Roll To Roll ◽  
Long Time ◽  
Liquid Flame Spray

Abstract Superhydrophobic nanoparticle coating was created on the surface of board using liquid flame spray (LFS). The LFS coating was carried out continuously in ambient conditions without any additional hydrophobization steps. The contact angle of water (CAW) of ZrO2, Al2O3 and TiO2 coating was adjusted reversibly from >150° down to ~10−20° using different stimulation methods. From industrial point of view, the controlled surface wetting has been in focus for a long time because it defines the liquid-solid contact area, and furthermore can enhance the mechanical and chemical bonding on the interface between the liquid and the solid. The used stimulation methods included batch-type methods: artificial daylight illumination and heat treatment and roll-to-roll methods: corona, argon plasma, IR (infra red)- and UV (ultra violet)-treatments. On the contrary to batch-type methods, the adjustment and switching of wetting was done only in seconds or fraction of seconds using roll-to-roll stimulation methods. This is significant in the converting processes of board since they are usually continuous, high volume operations. In addition, the creation of microfluidic patterns on the surface of TiO2 coated board using simple photomasking and surface stimulation was demonstrated. This provides new advantages and possibilities, especially in the field of intelligent printing. Limited durability and poor repellency against low surface tension liquids are presently the main limitations of LFS coatings.

scholarly journals Plant size, nutrient composition and biomass productivity of oats and faba bean in intercropping, and the effect of controlling Rhopalosiphum padi (Hom., Aphididae) on these properties

1990 ◽  
Vol 62 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Juha Helenius
Keyword(s):  
Faba Bean ◽  
Field Experiments ◽  
Rhopalosiphum Padi ◽  
Relative Yield ◽  
Biomass Productivity ◽  
Plant Size ◽  
Damage Function ◽  
Point Of View ◽  
Daily Maximum ◽  
Replacement Series

Effects of mixed intercropping on plant size, content of mineral nutrients and biomass yields were examined in three field experiments in Southern Finland in 1983—1985. The stand types were monocrops and replacement series of mixtures with 2/3 and 1/3 or 1/3 and 2/3 of oats (Avena sativa) and faba bean (Vicia faba), respectively. In one of the experiments control of R. padi, by means of deltamethrin sprayings, was an additional experimental factor having two levels. The height of stems or the above ground biomass of oats either were not affected or were increased by crop diversification. Bean plants remained smaller in the mixtures than in the monocrop. In plant size, there was a significant interaction between stand type and the effect of aphicide spraying: Oat benefitted most from being grown in the mixture containing most bean, and there was an indication (not statistically significant) that in these mixtures bean had proportionately higher weight loss. This result was interpreted as giving some support to the hypothesis of interspecific compensation between oats and bean against aphid damage to oats. In oats, the content of N, P, K, Ca, and Mg all decreased from the stage of inflorescence emergence to the stage of the onset of milk development. Mixed cropping increased the content in oats of all these nutrients except Ca. At the same time, contents of P and K in bean were decreased. The changes in growth form and composition in oats induced by intercropping are discussed from the point of view of host plant relationship and damage function of the aphid pest. In terms of relative yield total (RYT), there was no overyielding in the dry matter, and in one case only was there overyielding in the nitrogen. During the period of population growth of R. padi, the daily maximum temperatures within the canopy were higher in the mixtures than in the monocrop of oats.

scholarly journals Internal donors on supported Ziegler Natta catalysts for isotactic polypropylene: a brief tutorial review

2021 ◽  
Vol 28 (10) ◽  
Author(s):  
Bharat R. Paghadar ◽  
J. B. Sainani ◽  
Samith K. M. ◽  
Poornima Bhagavath
Keyword(s):  
Polymeric Materials ◽  
Detailed Comparison ◽  
Short Review ◽  
Point Of View ◽  
Polymer Science ◽  
Cross Combination ◽  
Polymer Properties ◽  
Technical Advances ◽  
Catalyst Systems ◽  
New Applications

AbstractThe scientific and technical advances in the field of polymer science has been abundant in recent years. Amongst the various polymeric materials available in market, synthesis of polyolefins has been in the forefront since decades. A major challenge in this domain remains in attaining stereoregular polyolefins especially polypropylene (PP) and significant efforts were carried out by synthesizing various internal donors (ID) aiding the catalysts involved in producing them. This short review gives an overview of i) various generations of Ziegler–Natta (ZN) catalyst systems ii) general classes of ID that has been demonstrated by the researchers over the past decades iii) their influence on PP isotacticity and polymer properties. The coordination modes of different donor classes on supported ZN system and comparative study especially between phthalate and diether ID classes were also addressed here. This review also presents the studies carried out on phthalate catalyst structure analysis, detailed comparison study on phthalate and diether IDs in terms of PP isotacticity, regioselectivity, hydrogen response, and also their cross combination study and competitive behavior. Further a brief description on other structurally varied IDs like malonates, maleates, silyl diol esters, bifunctional donors, multi ether donors demonstrated for isotactic PP were also presented. Studies conducted on compatibility of incorporation of two different classes of IDs on a single supported ZN system for the fundamental understanding of the catalyst behavior; and also on how mixed donor approach enables in tuning the catalyst for polymer properties were also presented. This review also provides an opportunity to the young minds and the basic researchers from academic point of view by and large to create new polymeric materials with useful properties or modify the existing materials for new applications by incorporating new IDs for further improvisation of the stereo regularity in obtaining the polymers. Graphic Abstract

scholarly journals Radiation in the Optical and UHF Range Emitted by Partial Discharges

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4334 ◽  
Author(s):  
Michał Kozioł ◽  
Łukasz Nagi ◽  
Michał Kunicki ◽  
Ireneusz Urbaniec
Keyword(s):  
Electromagnetic Waves ◽  
Electrical Power ◽  
Partial Discharges ◽  
Radio Waves ◽  
Insulation Systems ◽  
Surface Discharges ◽  
High Voltage Insulation ◽  
Solid Dielectrics ◽  
Electrode Systems ◽  
Optical Spectrophotometry

This paper presents the results of analysis of a solid dielectric’s influence on the phenomena associated with the signals emitted by surface partial discharges. Three types of electrode systems were tested, in which solid dielectrics made of pressboard, Teflon, and glass were used. The emission of such signals as radio waves in the Ultra high frequency (UHF) range and optical radiation was analyzed. The measurements were carried out in the insulation systems most commonly used in electrical power equipment, i.e., mineral oil and air. UHF and optical spectrophotometry methods were used to register the emitted signals. The obtained results indicate that the type of material from which the dielectric solid is made may have a potential impact on some ranges of emitted electromagnetic waves during the surface electrical discharges. The research topic undertaken is important in issues associated with high-voltage insulation systems and in particular with surface discharges, which are often the cause of their damage.

Prediction of Relative Motion and Probability of Contact Between FPSO and Shuttle Tanker in Tandem Offloading Operation

2002 ◽  
Author(s):  
Haibo Chen ◽  
Torgeir Moan ◽  
Sverre Haver ◽  
Kjell Larsen
Keyword(s):  
North Sea ◽  
Extreme Values ◽  
Simulation Models ◽  
Point Of View ◽  
Simulation Code ◽  
The North ◽  
Simulation Based ◽  
The North Sea ◽  
Sensitivity Studies ◽  
Tandem Offloading

Tandem offloading safety between FPSO and shuttle tanker is under concern. A few collisions between the two vessels have happened in the North Sea in recent years. In these incidents, excessive relative motions (termed as surging and yawing in this paper) between FPSO and tanker are identified as “failure prone situations” which have contributed to the initiation of most collision incidents. To quantitatively assess the probability of surging and yawing events, and more importantly, to effectively reduce their occurrence in tandem offloading operation, we present a simulation-based approach in this paper, which is carried out by a state-of-the-art time-domain simulation code SIMO. The SIMO simulation models are setup and calibrated for a typical North Sea purpose-built FPSO and a DP shuttle tanker. This 2-vessel system motion in tandem offloading is simulated. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models. This gives out probabilities of surging and yawing events. Sensitivity studies are performed to analyze contributions from various technical and operational factors. Measures to minimize the occurrence of surging and yawing from design and operational point of view are proposed.

UV-Irradiation Effects on Interfacial Strength between Thin Ceramic Film and Polymer Substrate

2005 ◽  
Vol 297-300 ◽  
pp. 2284-2289 ◽  
Author(s):  
Masaki Omiya ◽  
Hirotsugu Inoue ◽  
Kikuo Kishimoto ◽  
Masaaki Yanaka ◽  
Noritaka Ihashi
Keyword(s):  
Adhesion Strength ◽  
Uv Irradiation ◽  
Interfacial Adhesion ◽  
Interfacial Strength ◽  
Ultra Violet ◽  
Peel Test ◽  
Polymeric Materials ◽  
Polymer Substrate ◽  
Ceramic Films ◽  
Interfacial Adhesion Strength

This aim of this study is to investigate the effect of UV (Ultra Violet ray) irradiation on the interfacial adhesion strength between thin ceramic films and polymer substrate. Electric conductive films based on polymer substrates have attracted attention for use in flexible optoelectronic devices. It is well known that the mechanical properties of polymeric materials are degraded by UV irradiation. Therefore, it is considered that the UV irradiation also affects the interfacial adhesion strength between ceramic coating and polymer substrate. The interfacial adhesion strength was measured by Multi-stages peel test. The results show that the interfacial strength decreases with UV irradiation. However, if a filter layer is installed between ceramic and polymer substrate, the degradation ratio becomes small.

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