Classification of Slamming Events in Irregular Waves Measured through Tow Tank Experiments

2021 ◽  
Author(s):  
Mark Shepheard ◽  
Carolyn Q. Judge ◽  
Christine M. Gilbert
Keyword(s):  
High Speed ◽  
Irregular Waves ◽  
Ride Quality ◽  
Singular Value Decomposition Method ◽  
Depth Analysis ◽  
Time Histories ◽  
Design Loads ◽  
Modeling And Experiments ◽  
Value Decomposition ◽  
Distinct Features

Slamming events are the source of critical design loads for small, high-speed craft. Categorization of slamming events can prove useful by identifying cases of interest for more in-depth analysis, such as high-fidelity modeling and experiments. Inspired by developments in facial recognition techniques, a quantitative method is proposed to sort slamming events using various experimental measurements. A singular value decomposition method on a matrix assembled of vectors of time-histories of rigid body motions recorded in free-to-heave-and-pitch tow tank experiments on a planing hull. While some of the categories identified in this work show distinct features in slamming accelerations consistent with previously identified categories, other categories have also been identified. These results can be used when evaluating ride quality, and design loads, and performing more in-depth studies on specific slamming categories.

Basic Studies of Flow-Instability Inception in Axial Compressors Using Eigenvalue Method

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Xiaohua Liu ◽  
Dakun Sun ◽  
Xiaofeng Sun
Keyword(s):  
High Speed ◽  
Flow Instability ◽  
Flow Perturbation ◽  
Axial Compressors ◽  
Singular Value Decomposition Method ◽  
Onset Point ◽  
Eigenvalue Method ◽  
Point Calculation ◽  
Basic Studies ◽  
Value Decomposition

This paper applies a theoretical model developed recently to calculate the flow-instability inception of an axial transonic single stage compressor. After several calculation methods are compared, the singular value decomposition method is adopted to solve the resultant eigenvalue problem in which the involved matrix is rather large due to multistage configuration. The onset point of flow instability is judged by the imaginary part of the resultant eigenvalue. The effect of flow compressibility on the stall onset point calculation for the transonic rotor is studied. It is shown that the compressibility of flow perturbation plays a major role in computing high speed compressor flow stability.

Experimental Investigation vs Numerical Simulation of the Dynamic Response of a Moored Floating Structure to Waves

2014 ◽  
Author(s):  
Daniele Dessi ◽  
Sara Siniscalchi Minna
Keyword(s):  
Dynamical Behavior ◽  
Irregular Waves ◽  
Mooring Line ◽  
Floating Structure ◽  
Mooring Lines ◽  
Wave Energy Converters ◽  
Time Histories ◽  
Actual Configuration ◽  
Proper Orthogonal ◽  
Dynamic Wave

A combined numerical/theoretical investigation of a moored floating structure response to incoming waves is presented. The floating structure consists of three bodies, equipped with fenders, joined by elastic cables. The system is also moored to the seabed with eight mooring lines. This corresponds to an actual configuration of a floating structure used as a multipurpose platform for hosting wind-turbines, aquaculture farms or wave-energy converters. The dynamic wave response is investigated with numerical simulations in regular and irregular waves, showing a good agreement with experiments in terms of time histories of pitch, heave and surge motions as well as of the mooring line forces. To highlight the dynamical behavior of this complex configuration, the proper orthogonal decomposition is used for extracting the principal modes by which the moored structure oscillates in waves giving further insights about the way waves excites the structure.

scholarly journals Distributed Singular Value Decomposition Method for Fast Data Processing in Recommendation Systems

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2284
Author(s):  
Krzysztof Przystupa ◽  
Mykola Beshley ◽  
Olena Hordiichuk-Bublivska ◽  
Marian Kyryk ◽  
Halyna Beshley ◽  
...  
Keyword(s):  
Distributed Systems ◽  
Singular Value Decomposition ◽  
Data Processing ◽  
Message Passing ◽  
Message Passing Interface ◽  
Recommendation Systems ◽  
Singular Value ◽  
Singular Value Decomposition Method ◽  
Value Decomposition ◽  
Svd Method

The problem of analyzing a big amount of user data to determine their preferences and, based on these data, to provide recommendations on new products is important. Depending on the correctness and timeliness of the recommendations, significant profits or losses can be obtained. The task of analyzing data on users of services of companies is carried out in special recommendation systems. However, with a large number of users, the data for processing become very big, which causes complexity in the work of recommendation systems. For efficient data analysis in commercial systems, the Singular Value Decomposition (SVD) method can perform intelligent analysis of information. With a large amount of processed information we proposed to use distributed systems. This approach allows reducing time of data processing and recommendations to users. For the experimental study, we implemented the distributed SVD method using Message Passing Interface, Hadoop and Spark technologies and obtained the results of reducing the time of data processing when using distributed systems compared to non-distributed ones.

An Experimental Investigation of the Auto-Ignition Properties of Two C5 Esters: Methyl Butanoate and Butyl Methanoate

2007 ◽  
Author(s):  
Stephen M. Walton ◽  
Carlos Perez ◽  
Margaret S. Wooldridge
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Combustion Engine ◽  
Low Temperature Combustion ◽  
Moderate Pressure ◽  
Molecular Weights ◽  
Auto Ignition ◽  
Methyl Butanoate ◽  
Temperature Combustion ◽  
Time Histories

Ignition studies of two small esters were performed using a rapid compression facility (RCF). The esters (methyl butanoate and butyl methanoate) were chosen to have matching molecular weights, and C:H:O ratios, while varying the lengths of the constituent alkyl chains. The effect of functional group size on ignition delay time was investigated using pressure time-histories and high speed digital imaging. The mixtures studied covered a range of conditions relevant to oxygenated fuels and fuel additives, including bio-derived fuels. Low temperature and moderate pressure conditions were selected for study due to their relevance to advanced low temperature combustion strategies, and internal combustion engine conditions. The results are discussed in terms of the reaction pathways affecting the ignition properties.

Aggregation Method of Multi-Criteria Evaluations in New and Renewable Energy Power Plants: A Case Study

2009 ◽  
Author(s):  
Jiang-Jiang Wang ◽  
Chun-Fa Zhang ◽  
You-Yin Jing
Keyword(s):  
Renewable Energy ◽  
Nuclear Power ◽  
Power Plants ◽  
Economic Cost ◽  
Evaluation Result ◽  
Singular Value Decomposition Method ◽  
Multi Criteria Evaluation ◽  
Potential Development ◽  
Value Decomposition ◽  
Grey Relational

The multi-criteria evaluation methods of complex systems such as the new and renewable technologies gradually spring up. The feasibility of energy power plants is evaluated and considered from many aspects, such as technology, economic cost and environment protection. However, the energy power plants’ ranking results in different methods or different weighs can be different. Accordingly, the sequencing results should be aggregated and analyzed, and then an integrated result should be given out. Aiming to get the specific evaluation result, 10 kinds of energy power plants, such as hydro, nuclear, wind, geothermal and biomass plants are considered and evaluated. The singular value decomposition method is employed to aggregate the evaluation results in grey relational method, PROMENTHEE II method, and other results from literature. The integrated evaluation result shows that the hydro and nuclear power plants are located on the first place and the renewable energy power plants have great potential development in the future.

Dynamic contraction and fatigue analysis in biceps brachii muscles using synchrosqueezed wavelet transform and singular value features

2021 ◽  
pp. 095441192110480
Author(s):  
Lakshmi M Hari ◽  
Gopinath Venugopal ◽  
Swaminathan Ramakrishnan
Keyword(s):  
Wavelet Transform ◽  
Biceps Brachii ◽  
Singular Value ◽  
Time Frequency ◽  
Singular Value Decomposition Method ◽  
Dynamic Contractions ◽  
Synchrosqueezed Wavelet Transform ◽  
Value Decomposition ◽  
Neuromuscular Conditions ◽  
Semg Signals

In this study, the dynamic contractions and the associated fatigue condition in biceps brachii muscle are analysed using Synchrosqueezed Wavelet Transform (SST) and singular value features of surface Electromyography (sEMG) signals. For this, the recorded signals are decomposed into time-frequency matrix using SST. Two analytic functions namely Morlet and Bump wavelets are utilised for the analysis. Singular Value Decomposition method is applied to this time-frequency matrix to derive the features such as Maximum Singular Value (MSV), Singular Value Entropy (SVEn) and Singular Value Energy (SVEr). The results show that both these wavelets are able to characterise nonstationary variations in sEMG signals during dynamic fatiguing contractions. Increase in values of MSV and SVEr with the progression of fatigue denotes the presence of nonstationarity in the sEMG signals. The lower values of SVEn with the progression of fatigue indicate the randomness in the signal. Thus, it appears that the proposed approach could be used to characterise dynamic muscle contractions under varied neuromuscular conditions.

scholarly journals Effect of the turning characteristics of underfloor wheel lathes on the evolution of wheel polygonisation

2018 ◽  
Vol 233 (5) ◽  
pp. 479-488 ◽  
Author(s):  
Dabin Cui ◽  
Boyang An ◽  
Paul Allen ◽  
Ruichen Wang ◽  
Ping Wang ◽  
...  
Keyword(s):  
Fourth Order ◽  
High Speed ◽  
Higher Order ◽  
Ride Quality ◽  
Sustained Use ◽  
High Speed Trains ◽  
Cut Quality ◽  
Multiple Unit ◽  
Component Failures

During both running and wheel cut operations, wheels of railway vehicles and the friction rollers that support and drive the wheelset on a typical wheel cut lathe are subject to wear and hence are likely to develop out-of-round characteristics after sustained use. The resulting out-of-round wheels can significantly affect the ride quality and can potentially increase the incidence of fatigue-related component failures due to the resulting higher intensity loading cycles. Furthermore, the corresponding out-of-round characteristics of the lathe's friction rollers will continue to degrade the subsequent cut quality of wheels. For the analysis of the out-of-round characteristics caused by an underfloor wheel lathe used for the high-speed trains in China, a mathematical model based on a typical electric multiple unit (EMU) vehicle's wheelsets and their interactions with the wheel lathe friction rollers was established. Factors influencing the cut quality of the wheels, including the number of cuts, eccentricity forms of the friction rollers and the longitudinal spacing of the two rollers, have been analysed. The results show that two cuts can effectively remove the higher order polygon on the wheel surface. The eccentricity and phase angle of the friction rollers have no influence on the cut quality of higher order polygons, whereas they are the primary cause for the fourth-order polygons. The severity of the fourth-order polygon depends on the level and the phase of the eccentricity of the friction rollers. The space of the two rollers can also significantly affect the cut quality. Obtaining the theoretical and practical value for the maintenance of polygonised wheels using the underfloor lathe is the main outcome of this study.

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