scholarly journals Dimensional analysis of partial discharge initiated by a metallic particle adhering to the spacer surface in a gas-insulated system

2021 ◽  
Vol 6 (2) ◽  
pp. 91-100
Author(s):  
Firmansyah Nur Budiman ◽  
Ali Muhammad Rushdi
Keyword(s):  
Dimensional Analysis ◽  
Quantitative Information ◽  
Qualitative Reasoning ◽  
Partial Discharges ◽  
Sulphur Hexafluoride ◽  
Metallic Particles ◽  
Matrix Operations ◽  
Voltage Application ◽  
The Common ◽  
Pi Theorem

Partial discharges (PDs) constitute important phenomena in a Gas-Insulated System (GIS) that warrant recognition (and, subsequently, mitigation) as they are obvious symptoms of system degradation. This paper proposes the application of dimensional analysis, based on Buckingham pi theorem, for characterizing PDs provoked by the presence of metallic particles adhering to the spacer surface in a GIS employing SF6 (Sulphur hexafluoride). The ultimate goal of the analysis is to formulate the relationships that express three PD indicator quantities, namely current, charge, and energy, in terms of six independent quantities that collectively influence these indicators. These six quantities (henceforth referred to as the influencing, determining or affecting variables) include the level of applied voltage, the SF6 pressure, the length and position of the particle on the spacer, the duration of voltage application, and the gap between electrodes. To compute the pertinent dimensionless products, we implement three computational methods based on matrix operations. These three methods produce exactly the same dimensionless products, which are subsequently used for constructing the models depicting the relationships between each of the three PD dependent quantities and the common six determining variables. The models derived provide partial quantitative information and facilitate qualitative reasoning about the considered phenomenon.

A Framework for Building Behavioral Models for Design-Stage Failure Identification Using Dimensional Analysis

2010 ◽  
Author(s):  
Eric Coatane´a ◽  
Tuomas Ritola ◽  
Irem Y. Tumer ◽  
David Jensen
Keyword(s):  
Dimensional Analysis ◽  
Behavioral Model ◽  
Qualitative Reasoning ◽  
Design Stage ◽  
Critical Event ◽  
Behavioral Models ◽  
New Approach ◽  
Design Variables ◽  
Qualitative Physics ◽  
Failure Identification

In this paper, a design-stage failure identification framework is proposed using a modeling and simulation approach based on Dimensional Analysis and qualitative physics. The proposed framework is intended to provide a new approach to model the behavior in the Functional-Failure Identification and Propagation (FFIP) framework, which estimates potential faults and their propagation paths under critical event scenarios. The initial FFIP framework is based on combining hierarchical system models of functionality and configuration, with behavioral simulation and qualitative reasoning. This paper proposes to develop a behavioral model derived from information available at the configuration level. Specifically, the new behavioral model uses design variables, which are associated with units and quantities (i.e., Mass, Length, Time, etc…). The proposed framework continues the work to allow the analysis of functional failures and fault propagation at a highly abstract system concept level before any potentially high-cost design commitments are made. The main contribution in this paper consists of developing component behavioral models based on the combination of fundamental design variables used to describe components and their units or quantities, more precisely describing components’ behavior.

scholarly journals Characterization of venturi injector using dimensional analysis

2019 ◽  
Vol 23 (7) ◽  
pp. 484-491 ◽  
Author(s):  
Luiz R. Sobenko ◽  
José A. Frizzone ◽  
Antonio P. de Camargo ◽  
Ezequiel Saretta ◽  
Hermes S. da Rocha
Keyword(s):  
Dimensional Analysis ◽  
Flow Rate ◽  
Injection Rate ◽  
Operating Conditions ◽  
Functional Tests ◽  
Injection Flow Rate ◽  
Injection Flow ◽  
Hydraulic Conditions ◽  
Fluid Properties ◽  
Pi Theorem

ABSTRACT Venturi injectors are commonly employed for fertigation purposes in agriculture, in which they draw fertilizer from a tank into the irrigation pipeline. The knowledge of the amount of liquid injected by this device is used to ensure an adequate fertigation operation and management. The objectives of this research were (1) to carry out functional tests of Venturi injectors following requirements stated by ISO 15873; and (2) to model the injection rate using dimensional analysis by the Buckingham Pi theorem. Four models of Venturi injectors were submitted to functional tests using clean water as motive and injected fluid. A general model for predicting injection flow rate was proposed and validated. In this model, the injection flow rate depends on the fluid properties, operating hydraulic conditions and geometrical characteristics of the Venturi injector. Another model for estimating motive flow rate as a function of inlet pressure and differential pressure was adjusted and validated for each size of Venturi injector. Finally, an example of an application was presented. The Venturi injector size was selected to fulfill the requirements of the application and the operating conditions were estimated using the proposed models.

scholarly journals A method to reduce ambiguities of qualitative reasoning for conceptual design applications

2013 ◽  
Vol 27 (1) ◽  
pp. 19-35
Author(s):  
Valentina D'Amelio ◽  
Magdalena K. Chmarra ◽  
Tetsuo Tomiyama
Keyword(s):  
Qualitative Methods ◽  
Conceptual Design ◽  
Software Tool ◽  
Quantitative Information ◽  
Qualitative Reasoning ◽  
Interaction Method ◽  
Research Results ◽  
Practical Applications ◽  
New Feature ◽  
Knowledge Intensive

AbstractQualitative reasoning can generate ambiguous behaviors due to the lack of quantitative information. Despite many different research results focusing on ambiguities reduction, fundamentally it is impossible to totally remove ambiguities with only qualitative methods and to guarantee the consistency of results. This prevents the wide use of qualitative reasoning techniques in practical situations, particularly in conceptual design, where qualitative reasoning is considered intrinsically useful. To improve this situation, this paper initially investigates the origin of ambiguities in qualitative reasoning. Then it proposes a method based on intelligent interventions of the user who is able to detect ambiguities, to prioritize interventions on these ambiguities, and to reduce ambiguities based on the least commitment strategy. This interaction method breaks through the limit of qualitative reasoning in practical applications to conceptual design. The method was implemented as a new feature in a software tool called the Knowledge Intensive Engineering Framework in order to be tested and used for a printer design.

Improving seismic image using the common-horizon panel

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. S449-S458
Author(s):  
Lu Liu
Keyword(s):  
Time Lag ◽  
Velocity Model ◽  
Migration Velocity ◽  
Quantitative Information ◽  
Time Shift ◽  
Velocity Models ◽  
Seismic Image ◽  
The Common ◽  
Seismic Images ◽  
Zero Time

Generating high-quality seismic images requires accurate velocity models. However, velocity errors are predictably brought into the models. To mitigate the influences of velocity errors, we have used the common-horizon panel (CHP) for migration velocity analysis. CHP provides quantitative information to adjust mispositioned interfaces or correct deformed wavefields, which leads to improved image quality. It is generated by extrapolating seismic gathers to a selected target horizon and applying the time-shift imaging condition. Compared with the commonly used common-image gathers, the events in CHPs are more trackable because geologic interfaces are typically continuous in space. For a correct velocity model, the panel indicates a flat event at zero time lag, whereas in the case of an erroneous velocity model, the event becomes kinematically oscillating. This distinguishing difference provides a practical criterion to verify whether the migration velocity model is correct and to estimate the velocity or wavefield errors based on how much the event deviates from zero time lag. Tests on synthetic and field data sets have shown that the seismic images are improved by using the proposed CHP technique.

scholarly journals Performance Evaluation and Dimensional Analysis of Multistage Helicoaxial Pump for Two-Phase Flow

2019 ◽  
Vol 4 (3) ◽  
pp. 22 ◽  
Author(s):  
Patil ◽  
Gudigopuram ◽  
Ayyildiz ◽  
Delgado ◽  
Morrison
Keyword(s):  
Dimensional Analysis ◽  
Two Phase Flow ◽  
Power Input ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Phase Flow ◽  
Two Phase ◽  
Fluid Properties ◽  
The Common ◽  
Phase Fluid

A four stage helicoaxial pump was tested under varying operating conditions. A range of inlet pressures, rotational speeds (3000, 3600 rpm), and gas void fractures (GVFs) were considered for two fluid viscosities. The head developed and power input to run the pump were recorded. Head, power input and efficiency decrease as the GVF increases with best efficiency point (BEP) moving towards lower flow rate conditions. Dimensional analysis was conducted to evaluate the applicability of current affinity laws to the two-phase flow performance of the pump under consideration. Dimensionless head coefficient and power coefficients were defined for two-phase flow, considering the homogeneity in the two-phase fluid properties. Deviations in the two-phase affinity coefficients from the common law curve increases with GVF. To bridge this gap, a new correlation is proposed with a revised flow coefficient that allows all the head coefficient data to collapse on a single line with a greater degree of accuracy.

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