scholarly journals Computationally Efficient Estimation of the Electric-Field Maximums for the MFT Insulation Coordination

2019 ◽  
Author(s):  
Marko Mogorovic ◽  
Drazen Dujic
Keyword(s):  
Electric Field ◽  
Efficient Estimation ◽  
Computationally Efficient ◽  
Insulation Coordination

scholarly journals The Electrical Behaviour of a Medium Voltage Polymer Insulator with Deposited Moss Layer on the Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 6409-6414
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Point Of View ◽  
Electrical Behaviour ◽  
Medium Voltage ◽  
High Frequency Structure Simulator ◽  
Polymer Insulator ◽  
Risk Areas ◽  
Proper Design ◽  
Insulation Coordination

This paper presents a study on the voltage and electric fields behaviours of a 10kV polymer insulator with moss deposited under dry (air) condition. The aim of this study is considering on the electrical behaviour of insulator by having a surface layer of moss on it that can change the withstand voltage of insulators. It should be mentioned that these moss layers are commonly crated in the jungles especially in the tropical countries. To study on the above mentioned case, simulations were carried out using ANSYS High Frequency Structure Simulator (HFSS). The simulation insulator modelling includes the computerized evaluation of voltage and electric field distribution at three different locations for both clean and moss contaminated insulators. Noted that the electric field and also voltage profiles at different parts of insulators has been determined using applied simulated model. The moss contamination polymer insulator displayed a discontinuous distribution of the electric field compared to the clean insulator and their voltage distribution decreased with distances from the source. The results indicated that electric field along the insulator surface were greatly affected by hydrophobicity characteristic of the polymer. Therefore, the surrounding air of the moss contaminated insulator was prone to initiate a flashover. This study can be helpful for designing the distribution lines especially in high risk areas to set a proper design from the point of view of insulation coordination.

scholarly journals Conditional Analysis for Mixed Covariates, with Application to Feed Intake of Lactating Sows

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
S. Y. Park ◽  
C. Li ◽  
S. M. Mendoza Benavides ◽  
E. van Heugten ◽  
A. M. Staicu
Keyword(s):  
Feed Intake ◽  
Dynamic Change ◽  
Estimation Algorithm ◽  
Joint Estimation ◽  
Efficient Estimation ◽  
Specific Information ◽  
Computationally Efficient ◽  
Modeling Framework ◽  
Lactating Sows ◽  
Information Vector

We propose a novel modeling framework to study the effect of covariates of various types on the conditional distribution of the response. The methodology accommodates flexible model structure, allows for joint estimation of the quantiles at all levels, and provides a computationally efficient estimation algorithm. Extensive numerical investigation confirms good performance of the proposed method. The methodology is motivated by and applied to a lactating sow study, where the primary interest is to understand how the dynamic change of minute-by-minute temperature in the farrowing rooms within a day (functional covariate) is associated with low quantiles of feed intake of lactating sows, while accounting for other sow-specific information (vector covariate).

scholarly journals The Implementation of an Explicit Charging and Discharge Lightning Scheme within the WRF-ARW Model: Benchmark Simulations of a Continental Squall Line, a Tropical Cyclone, and a Winter Storm

2013 ◽  
Vol 141 (7) ◽  
pp. 2390-2415 ◽  
Author(s):  
Alexandre O. Fierro ◽  
Edward R. Mansell ◽  
Donald R. MacGorman ◽  
Conrad L. Ziegler
Keyword(s):  
Electric Field ◽  
Wrf Model ◽  
Squall Line ◽  
Discharge Process ◽  
Computationally Efficient ◽  
Winter Storm ◽  
Breakdown Threshold ◽  
Convective Systems ◽  
Grid Points ◽  
Total Lightning

AbstractThis work describes the recent implementation of explicit lightning physics within the Weather Research and Forecasting (WRF) Model. Charging of hydrometeors consists of five distinct noninductive parameterizations, polarization of cloud water, and the exchange of charge during collisional mass transfer. The three components of the ambient electric field are explicitly solved for via the computationally efficient multigrid elliptic solver. The discharge process employs concepts adapted from two well-documented bulk lightning models, whereby charge reduction is imposed within a prescribed volume centered at grid points characterized by electric field magnitudes exceeding a given breakdown threshold.This lightning model was evaluated through benchmark convection-allowing (3 km) model simulations of three contrasting convective systems: a continental squall line, a major hurricane (Rita 2005), and a winter storm. The areal coverage and magnitude of the simulated hourly flash origin density (FOD) for the continental squall line are qualitatively comparable to that of the total lightning data observations from Earth Networks Total Lightning Network (ENTLN). In agreement with the ENTLN observations, no FOD are simulated for the winter storm case. The simulated spatial FOD pattern of the hurricane and the eyewall gross charge structure were both in reasonable agreement with observations. The simulated FOD for all three cases were also evaluated against those obtained with the recently developed McCaul diagnostic lightning prediction schemes and exhibited overall good qualitative agreement with each other for Rita and the continental squall line.

Modeling of Supercritical Co2 Shell-and-Tube Heat Exchangers Under Extreme Conditions. Part 2: Heat Exchanger Model

2022 ◽  
Author(s):  
Akshay Bharadwaj Krishna ◽  
Kaiyuan Jin ◽  
Portnovo Ayyaswamy ◽  
Ivan Catton ◽  
Timothy S. Fisher
Keyword(s):  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Critical Role ◽  
Computation Time ◽  
Efficient Estimation ◽  
Working Fluid ◽  
Computationally Efficient ◽  
Thermal Cycles

Abstract Heat exchangers play a critical role in supercritical CO2 Brayton cycles by providing necessary waste heat recovery. Supercritical CO2 thermal cycles potentially achieve higher energy density and thermal efficiency operating at elevated temperatures and pressures. Accurate and computationally efficient estimation of heat exchanger performance metrics at these conditions is important for the design and optimization of sCO2 systems and thermal cycles. In this paper (Part II), a computationally efficient and accurate numerical model is developed to predict the performance of STHXs. Highly accurate correlations reported in Part I of this study are utilized to improve the accuracy of performance predictions, and the concept of volume averaging is used to abstract the geometry and reduce computation time. The numerical model is validated by comparison with CFD simulations and provides high accuracy and significantly lower computation time compared to existing numerical models. A preliminary optimization study is conducted and the advantage of using supercritical CO2 as a working fluid for energy systems is demonstrated.

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