scholarly journals Correlation between Dielectric Loss and Partial Discharge of Oil-Pressboard Insulation

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 864
Author(s):  
Yan Li ◽  
Min Li ◽  
Jun Xie
Keyword(s):  
Dielectric Loss ◽  
Information Asymmetry ◽  
Partial Discharge ◽  
Testing Procedure ◽  
Statistical Parameters ◽  
Asymmetric Component ◽  
Status Assessment ◽  
Set Up ◽  
Variation Mechanism ◽  
Two Parameters

Dielectric loss tand and partial discharge (PD) are important indicators for status assessment of oil-pressboard insulation. The correlation characteristics between these two parameters has significance for understanding the material’s degradation and helps to eliminate the information asymmetry for diagnostics. In this paper, the symmetric experimental platform is set up to measure the dielectric loss tand and PD for oil-pressboard insulation following the designed testing procedure consisted of raised and rested voltages. Three sets of samples with different water content were tested. The variation mechanism of tand with voltage is explained by proposed equivalent circuit, which introduced an asymmetric component representing defect part. PDs are found to be symmetric in the sinusoidal voltage cycles and their statistical parameters are calculated. Besides, the correlation between dielectric loss difference from raised voltage to rested voltage and PD is researched. Strong correlation is observed between dielectric loss and PD, which offers degradation insight for oil-pressboard insulation and helps to eliminate information asymmetry for material status diagnostics.

scholarly journals Analysis of Errors in the Estimation of Impact Positions in Plate-Like Structure through the Triangulation Formula by Piezoelectric Sensors Monitoring

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3426 ◽  
Author(s):  
Eugenio Marino-Merlo ◽  
Andrea Bulletti ◽  
Pietro Giannelli ◽  
Marco Calzolai ◽  
Lorenzo Capineri
Keyword(s):  
Propagation Velocity ◽  
Lamb Waves ◽  
Correlation Method ◽  
Time Of Arrival ◽  
Impact Point ◽  
Laboratory Procedure ◽  
Impact Position ◽  
Set Up ◽  
Two Parameters ◽  
The Impact

The structural health monitoring (SHM) of critical structures is a complex task that involves the use of different sensors that are also aimed at the identification of the location of the impact point using ultrasonic sensors. For the evaluation of the impact position, reference is often made to the well-known triangulation method. This method requires the estimation of the differential time of arrival (DToA) and the group velocity of the Lamb waves propagating into a plate-like structure: the uncertainty of these two parameters is taken into consideration as main cause of localization error. The work proposes a simple laboratory procedure based on a set-up with a pair of sensors that are symmetrically placed with respect to the impact point, to estimate the uncertainty of the DToA and the propagation velocity estimates. According to a theoretical analysis of the error for the impact position, the experimental uncertainties of DToA and the propagation velocity are used to estimate the overall limit of the SHM system for the impact positioning. Because the error for the DToA estimate depends also on the adopted signal processing, three common methods are selected and compared: the threshold, the correlation method, and a likelihood algorithm. Finally, the analysis of the positioning error using multisensory configuration is reported as useful for the design of the SHM system.

scholarly journals QSAR-Co-X: An Open Source Toolkit for Multi-Target QSAR Modelling

2020 ◽  
Author(s):  
M. Natália Dias Soeiro Cordeiro ◽  
Amit Kumar Halder
Keyword(s):  
Open Source ◽  
Linear Models ◽  
Moving Average ◽  
Biological Data ◽  
Statistical Parameters ◽  
Computational Tools ◽  
Qsar Modelling ◽  
Qsar Models ◽  
Quantitative Structure Activity Relationships ◽  
Set Up

Abstract Quantitative structure activity relationships (QSAR) modelling is a well-known computational tool, often used in a wide variety of applications. Yet one of the major drawbacks of conventional QSAR modelling tools is that models are set up based on a limited number of experimental and/or theoretical conditions. To overcome this, the so-called multitasking or multi-target QSAR (mt-QSAR) approaches have emerged as new computational tools able to integrate diverse chemical and biological data into a single model equation, thus extending and improving the reliability of this type of modelling. We have developed QSAR-Co-X, an open source python−based toolkit (available to download at https://github.com/ncordeirfcup/QSAR-Co-X) for supporting mt-QSAR modelling following the Box-Jenkins moving average approach. The new toolkit embodies several functionalities for dataset selection and curation plus computation of descriptors, for setting up linear and non-linear models, as well as for a comprehensive results analysis. The workflow within this toolkit is guided by a cohort of multiple statistical parameters along with graphical outputs onwards assessing both the predictivity and the robustness of the derived mt-QSAR models. To monitor and demonstrate the functionalities of the designed toolkit, three case-studies pertaining to previously reported datasets are examined here. We believe that this new toolkit, along with our previously launched QSAR-Co code, will significantly contribute to make mt-QSAR modelling widely and routinely applicable.

scholarly journals A NEW HYBRID APPROACH IN THE CALIBRATION OF BOUSSINESQ-TYPE WAVE BREAKING MODELS

2018 ◽  
pp. 24
Author(s):  
Joaquín Moris ◽  
Patricio Catalán ◽  
Rodrigo Cienfuegos
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Numerical Models ◽  
Hybrid Approach ◽  
Boussinesq Equations ◽  
Water Levels ◽  
Statistical Parameters ◽  
Time Space ◽  
Forcing Mechanisms ◽  
Set Up

Wave breaking is one of the main forcing mechanisms in coastal hydrodynamics, driving mean water levels and currents. Understanding its behavior is key in the goal of improving our comprehension of coastal morphodynamics variations. One way to improve our understanding is through the use of numerical models, such as phase-resolving numerical models based on the Boussinesq equations (Kirby, 2016), which are modified to include breaking by the inclusion of a breaking criteria and a dissipation mechanism. Since there is not a universal law capable of characterizing the wave breaking, the existing models must be calibrated. Traditionally, this is done by adjusting wave height profiles and other free surface statistical parameters without explicitly considering the time-space location and duration of the breaking process. Consequently, it is possible to calibrate a model that accurately represents wave elevation statistics parameters, such as wave height and wave set-up; however, it might not necessarily represent the breaking location-duration and therefore, the forcing.

scholarly journals Extrasolar planet interactions

2007 ◽  
Vol 3 (S249) ◽  
pp. 469-478
Author(s):  
Rory Barnes ◽  
Richard Greenberg
Keyword(s):  
Planetary Systems ◽  
Equal Mass ◽  
Dynamical Instability ◽  
Hill Stability ◽  
Resonant Interactions ◽  
Stability And Instability ◽  
Different Types ◽  
Set Up ◽  
Type Of Stability ◽  
Two Parameters

AbstractThe dynamical interactions of planetary systems may be a clue to their formation histories. Therefore, the distribution of these interactions provides important constraints on models of planet formation. We focus on each system's apsidal motion and proximity to dynamical instability. Although only ∼25 multiple planet systems have been discovered to date, our analyses in these terms have revealed several important features of planetary interactions. 1) Many systems interact such that they are near the boundary between stability and instability. 2) Planets tend to form such that at least one planet's eccentricity periodically drops to near zero. 3) Mean-motion resonant pairs would be unstable if not for the resonance. 4) Scattering of approximately equal mass planets is unlikely to produce the observed distribution of apsidal behavior. 5) Resonant interactions may be identified through calculating a system's proximity to instability, regardless of knowledge of angles such as mean longitude and longitude of periastron (e.g. GJ 317 b and c are probably in a 4:1 resonance). These properties of planetary systems have been identified through calculation of two parameters that describe the interaction. The apsidal interaction can be quantified by determining how close a planet is to an apsidal separatrix (a boundary between qualitatively different types of apsidal oscillations, e.g. libration or circulation of the major axes). This value can be calculated through short numerical integrations. The proximity to instability can be measured by comparing the observed orbital elements to an analytic boundary that describes a type of stability known as Hill stability. We have set up a website dedicated to presenting the most up-to-date information on dynamical interactions: http://www.lpl.arizona.edu/~rory/research/xsp/dynamics.

How Can Ceramic Small-Medium Enterprises Access to Finance in China?

2010 ◽  
Vol 177 ◽  
pp. 427-429
Author(s):  
Rong Hui Hua ◽  
Li Wei Zhou
Keyword(s):  
Information Asymmetry ◽  
Social Service ◽  
External Environment ◽  
Credit System ◽  
Access To Finance ◽  
Set Up ◽  
Market Preference ◽  
Small Medium Enterprises ◽  
Medium Enterprises ◽  
Finance Department

It is necessary to discover the factors that block small-medium enterprises (SMEs) do financing successful. The paper describes market preference, credit system and social service which affect company doing finance by external environment. Moreover, information asymmetry and weak social service make SMEs do finance hard. The paper gives some suggestions such as set up a new finance department in the company, perfect credit system and social service.

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.

The influence of void configuration in statistical parameters of partial discharge signals

2013 ◽  
Author(s):  
Euler C. T. Macedo ◽  
Juan M. Mauricio Villanueva ◽  
Edson C. Guedes ◽  
Raimundo C. S. Freire ◽  
J. M. R. de Souza Neto ◽  
...  
Keyword(s):  
Partial Discharge ◽  
Statistical Parameters

Experimental Modal Analysis of a Half-Scale Model Twin-Engine Aircraft Rear Fuselage Engine Mount Support Frame

2017 ◽  
Author(s):  
Diego A. Chamberlain ◽  
Chris K. Mechefske
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Testing Procedure ◽  
Modal Testing ◽  
Scale Model ◽  
Mode Shapes ◽  
Component Testing ◽  
Fitting Procedures ◽  
Engine Mount ◽  
Set Up

Experimental modal testing using an impact hammer is a commonly used method for obtaining the modal parameters of any structure for which the vibrational behavior is of interest. Natural frequencies and associated mode shapes of the structure can be extracted directly from measured FRFs (Frequency Response Functions) through various curve fitting procedures. This paper provides an overview of the modal testing conducted on an aerospace component. Testing set-up, experimental equipment and the methodology employed are all described in detail. Further validation of the testing procedure was done by ensuring that the experimental results satisfy the requirements of repeatability, reciprocity and linearity. The relevant ISO standard has been referenced and important concepts to modal analysis are expanded upon. Recorded natural frequencies, coherence and a description of the observed mode shapes are presented along with notable trends.

scholarly journals Response of Different Machine Foundation Shapes Resting on Dry Sand to Dynamic Loading

2020 ◽  
Vol 27 (2) ◽  
pp. 29-39
Author(s):  
Khalid W. Abdul Kaream ◽  
Mohammed Y. Fattah ◽  
Zeyad S. M. Khaled
Keyword(s):  
Dynamic Loading ◽  
Pressure Sensors ◽  
Shaft Encoder ◽  
Supporting Soil ◽  
Different Depths ◽  
Dry Sand ◽  
Set Up ◽  
Two Parameters ◽  
College Of Engineering ◽  
Flexible Pressure Sensors

In this paper, the effect of footing shape resting on dry sand when subjected to machine dynamic loading is experimentally investigated. A laboratory set-up was prepared to simulate the case at different operating frequencies. Nine models were tested to examine the effects of the combinations of two parameters, including different frequencies of (0.5, 1, and 2 Hz) and different footing shapes (circular, square and rectangular). The tests were conducted under a load amplitude of (0.25 ton) using sand with medium and dense relative densities corresponding to (R.D. = 50% and 80%) having unit weights of (17.04 and 17.96 kN/m3) respectively. A shaft encoder and a vibration meter were used to measure the strain and amplitude displacement, while the stress in the soil at different depths was measured using flexible pressure sensors. It was found that the shape of footing has a considerable influence on the bearing capacity of the supporting soil under dynamic loading. For instance, the strain of dry sand under a circular footing was nearly (41%) higher, the amplitude displacement was nearly (17%) higher, and stress was nearly (12%) higher than square and rectangular footings, under the same conditions. @2019 TJES, College of Engineering, Tikrit University

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