A Study of Indicator Passage Error Correction Schemes

1991 ◽  
Vol 113 (3) ◽  
pp. 399-405
Author(s):  
B. G. Shiva Prasad ◽  
F. L. Heidrich
Keyword(s):  
Experimental Data ◽  
Error Correction ◽  
Time Domain ◽  
Prediction Accuracy ◽  
Method Of Characteristics ◽  
Measuring Transducer ◽  
Dynamic Effects ◽  
Pressure Time ◽  
Efficient Calculation ◽  
Frequency Domain Methods

The passage length between the cylinder and the measuring transducer is known to cause distortion of pressure time traces due to pulsations caused by dynamic effects. This paper attempts to arrive at a simple and efficient calculation scheme for correcting those distortions. Both time domain (method of characteristics approach) and frequency domain methods are evaluated to assess the importance of considering various effects for improving the prediction accuracy. The predictions from both methods are compared with experimental data as well as the results of Heidrich [6], who used simpler versions of these methods.

scholarly journals A Study of Developing a Prediction Equation of Electricity Energy Output via Photovoltaic Modules

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1503
Author(s):  
Minsu Kim ◽  
Hongmyeong Kim ◽  
Jae Hak Jung
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Air Temperature ◽  
Temperature Difference ◽  
Prediction Accuracy ◽  
Prediction Equation ◽  
Energy Output ◽  
Photovoltaic Modules ◽  
Mean Error ◽  
Pv Module

Various equations are being developed and applied to predict photovoltaic (PV) module generation. Currently, quite diverse methods for predicting module generation are available, with most equations showing accuracy with ≤5% error. However, the accuracy can be determined only when the module temperature and the value of irradiation that reaches the module surface are precisely known. The prediction accuracy of outdoor generation is actually extremely low, as the method for predicting outdoor module temperature has extremely low accuracy. The change in module temperature cannot be predicted accurately because of the real-time change of irradiation and air temperature outdoors. Calculations using conventional equations from other studies show a mean error of temperature difference of 4.23 °C. In this study, an equation was developed and verified that can predict the precise module temperature up to 1.64 °C, based on the experimental data obtained after installing an actual outdoor module.

scholarly journals A Hierarchical Bayes Error Correction Model to Explain Dynamic Effects of Price Changes

2006 ◽  
Vol 43 (3) ◽  
pp. 443-461 ◽  
Author(s):  
Dennis Fok ◽  
Csilla Horváth ◽  
Richard Paap ◽  
Philip Hans Franses
Keyword(s):  
Error Correction ◽  
Error Correction Model ◽  
Hierarchical Bayes ◽  
Dynamic Effects ◽  
Price Changes ◽  
Correction Model ◽  
Bayes Error

Analysis of Operating Deflection Shapes Based on Subspace Method

1997 ◽  
Author(s):  
Nobutaka Tsujiuchi ◽  
Yuichi Matsumura ◽  
Takayuki Koizumi
Keyword(s):  
Experimental Data ◽  
Time Domain ◽  
State Space Model ◽  
Measurement Data ◽  
Time Varying ◽  
Subspace Method ◽  
Identification Scheme ◽  
Space Model ◽  
Time Varying Systems ◽  
Frequency Components

Abstract In this paper, we propose the new method to identify the Operating Deflection Shapes (ODSs) from the measurement data of time domain. At first, we present the identification scheme of ODSs based on a state-space model. Then the scheme is extended to identify the ODSs adaptively for the time-varying systems by using the URV Decomposition (URVD). Proposed scheme is able to decompose the deformation of a structure under operating condition into the underlying superposition of well excited frequency components. This paper introduces the algorithm and shows the effectiveness of our proposed scheme applyed for both synthesized and experimental data.

Nonlinear Wave Crest Distribution on a Vertical Breakwater

2018 ◽  
Author(s):  
Valentina Laface ◽  
Giovanni Malara ◽  
Felice Arena ◽  
Ioannis A. Kougioumtzoglou ◽  
Alessandra Romolo
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Vertical Wall ◽  
Surface Elevation ◽  
Wave Crest ◽  
Height Distribution ◽  
Free Surface Elevation ◽  
Pressure Transducers ◽  
Pressure Time ◽  
Time Histories

The paper addresses the problem of deriving the nonlinear, up to the second order, crest wave height probability distribution in front of a vertical wall under the assumption of finite spectral bandwidth, finite water depth and long-crested waves. The distribution is derived by relying on the Quasi-Deterministic representation of the free surface elevation in front of the vertical wall. The theoretical results are compared against experimental data obtained by utilizing a compressive sensing algorithm for reconstructing the free surface elevation in front of the wall. The reconstruction is pursued by starting from recorded wave pressure time histories obtained by utilizing a row of pressure transducers located at various levels. The comparison shows that there is an excellent agreement between the proposed distribution and the experimental data and confirm the deviation of the crest height distribution from the Rayleigh one.

On the Application of Frequency-Domain Methods to Multistage Turbomachinery

2015 ◽  
Author(s):  
Laura Junge ◽  
Graham Ashcroft ◽  
Peter Jeschke ◽  
Christian Frey
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Harmonic Balance ◽  
Axial Compressor ◽  
Harmonic Balance Method ◽  
Nonlinear Frequency ◽  
Solution Quality ◽  
Multi Stage ◽  
Frequency Domain Methods ◽  
Blade Row

Due to the relative motion between adjacent blade rows the aerodynamic flow fields within turbomachinery are normally dominated by deterministic, periodic phenomena. In the numerical simulation of such unsteady flows (nonlinear) frequency-domain methods are therefore attractive as they are capable of fully exploiting the given spatial and temporal periodicity, as well as capturing or modelling flow nonlinearity. Central to the efficiency and accuracy of such frequency-domain methods is the selection of the frequencies and the circumferential modes to be resolved in simulations. Whilst trivial in the context of the simulation of a single compressor- or turbine-stage, the choice of solution modes becomes substantially more involved in multi-stage configurations. In this work the importance of mode scattering, in the context of the unsteady aerodynamic field, is investigated and quantified. It is shown that scattered modes can substantially impact the unsteady flow field and are essential for the accurate modelling of wake propagation within multistage configurations. Furthermore, an iterative approach is outlined, based on the spectral analysis of the circumferential modes at the interfaces between blade rows, to identify the dominant solution modes that should be resolved in the adjacent blade row. To demonstrate the importance of mode scattering and validate the approach for their identification the unsteady blade row interaction within a 4.5 stage axial compressor is computed using both the harmonic balance method and, based on a full annulus midspan simulation, a time-domain method. Through the inclusion of scattered modes it is shown that the solution quality of the harmonic balance results is comparable to that of the nonlinear time-domain simulation.

A Benchmark Study on Crushing and Cutting of Plated Structures

1997 ◽  
Vol 41 (02) ◽  
pp. 147-160
Author(s):  
Jeom Kee Paik ◽  
Tomasz Wierzbicki
Keyword(s):  
Experimental Data ◽  
Closed Form ◽  
Dynamic Effects ◽  
Crushing Strength ◽  
Closed Form Solutions ◽  
Cutting Resistance ◽  
Benchmark Study ◽  
Stiffened Structures ◽  
The Mean

A benchmark study on several closed-form solutions for the mean crushing strength and the cutting resistance of plated structures during collision or grounding is carried out by comparing theoretical solutions with experimental data. Based on expressions which have been derived for unstiffened structures, an extension of the methods is proposed for longitudinally and/or transversely stiffened structures. Dynamic effects on the crushing and cutting response are discussed, and applicability of the quasistatic formulations to analyze the crushing and cutting damage of the structure in the dynamic situations is investigated.

Analysis for Scattering of Non-homogeneous Medium by Time Domain Volume Shooting and Bouncing Rays

2021 ◽  
Vol 36 (3) ◽  
pp. 245-251
Author(s):  
Jun Li ◽  
Huaguang Bao ◽  
Dazhi Ding
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
High Efficiency ◽  
Homogeneous Medium ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Transient Electromagnetic ◽  
Frequency Domain Methods ◽  
Scattered Fields

In order to evaluate scattering from hypersonic vehicles covered with the plasma efficiently, time domain volume shooting and bouncing rays (TDVSBR) is first introduced in this paper. The new method is applied to solve the transient electromagnetic scattering from complex targets, which combines with non-homogeneous dielectric and perfect electric conducting (PEC) bodies. To simplify the problem, objects are discretized into tetrahedrons with different electromagnetic parameters. Then the reflection and transmission coefficients can be obtained by using theory of electromagnetic waves propagation in lossy medium. After that, we simulate the reflection and transmission of rays in different media. At last, the scattered fields or radiation are solved by the last exiting ray from the target. Compared with frequency-domain methods, time-domain methods can obtain the wideband RCS efficiently. Several numerical results are given to demonstrate the high efficiency and accuracy of this proposed scheme.

Determining Usefulness of Machine Learning in Materials Discovery Using Simulated Research Landscapes

2021 ◽  
Author(s):  
Marcos del Cueto ◽  
Alessandro Troisi
Keyword(s):  
Machine Learning ◽  
Experimental Data ◽  
Data Acquisition ◽  
Prediction Accuracy ◽  
New Materials

When existing experimental data are combined with machine learning (ML) to predict the performance of new materials, the data acquisition bias determines ML usefulness and the prediction accuracy. In this...

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