Online dimensional control of rolled steel profiles using projected fringes

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Mixed Fault Classification of Sensorless PMSM Drive in Dynamic Operations Based on External Stray Flux Sensors

This paper aims to classify local demagnetisation and inter-turn short-circuit (ITSC) on position sensorless permanent magnet synchronous motors (PMSM) in transient states based on external stray flux and learning classifier. Within the framework, four supervised machine learning tools were tested: ensemble decision tree (EDT), k-nearest neighbours (KNN), support vector machine (SVM), and feedforward neural network (FNN). All algorithms are trained on datasets from one operational profile but tested on other different operation profiles. Their input features or spectrograms are computed from resampled time-series data based on the estimated position of the rotor from one stray flux sensor through an optimisation problem. This eliminates the need for the position sensors, allowing for the fault classification of sensorless PMSM drives using only two external stray flux sensors alone. Both SVM and FNN algorithms could identify a single fault of the magnet defect with an accuracy higher than 95% in transient states. For mixed faults, the FNN-based algorithm could identify ITSC in parallel-strands stator winding and local partial demagnetisation with an accuracy of 87.1%.publishedVersio

Patenter som innovasjonsindikatorer : Komparativ analyse av 3 ulike bransjer i 4 nordiske land i perioden 1996 til 2005

Ved bruk av patentdatabasen USPTO (US Patent & Trademark Office) som inneholder samtlige amerikanske patenter og mønsterbeskyttelser, er det utført en analyse med formål å sammenligne patenteringsaktivitet i Norge, Danmark, Sverige og Finland for følgende tre bransjer: Kuldeteknikk, Offshoreteknikk, og Telekommunikasjon. Målet med denne undersøkelsen er en studie av: • Indikatorer for teknologisk utvikling og innovasjon. • Patenter benyttet som innovasjonsindikatorer. • Patenteringsaktivitet i tre ulike bransjer/patentklasser i fire forskjellige land. Fra analysen kan følgende oppsummeres: • Bruk av Patentstatistikk, ved å telle antall patenter, benyttes for å vurdere omfanget av patenteringen. Metoden gir imidlertid ikke det rette bildet av nyskapningsaktiviteten, da noen patenter aldri realiseres og andre benyttes kun for å blokkere for nye patenter. • Ved å normalisere antall registrerte patenter årlig med hensyn til de respektive lands innbyggere, viser resultatene at i land med større befolkningsgrunnlag patenteres mer. • Ved å se på dynamikken av denne prosessen globalt over tid, vil det gi et reelt bilde av de mekanismer som kan påvirke patenteringen (oppgang eller nedgang i bransjen). • Bruk av Patentstatistikk ved å telle antall siteringer: Både alder og antall patenter påvirker resultatene kraftig, og eldre patenter har normalt flere siteringer enn yngre patenter. • Ved å telle antall siteringer pr. patent fjernes koplingen (til en viss grad), men fortsatt er eldre patenter sitert oftere enn nyere patenter. • Ved å ”normalisere” antall siteringer pr. år antydes hvor viktige snittet av patentene er. Antallet siteringer avtar med tiden (som forventet). • Når antall nyere patenter øker vil det kompensere for redusert antall siteringer for disse patentene. Hvis WPC indikatoren synker, kan dette forklares med at antall nye patenter ikke øker så veldig. • RTCA – indikatoren benyttes for å få økt forståelse for landets spesialisering, og dette var meget fremtredende i denne analysen.• Lineær regresjonsanalyse benyttes for å vise snittet av antall siteringer av alle patenter, og kan gi svar på i hvilken grad det ene landets patenter siteres oftere enn patenter fra de øvrige land. Metoden gir også svar på om det ene landets patenter er ”bedre” enn det andre landets patenter. Videre trekkes følgende konklusjon: • Ved å knytte de analyserte bransjene mot de analyserte land ble følgende klart: I Norge er det olje- og gassbransjen med offshore utstyrsproduksjon som er størst, i Sverige og i Finland – telekommunikasjon og i Danmark - kuldeautomatikk

Mathematical modeling and parameters estimation of car crash using eigensystem realization algorithm and curve-fitting approaches

Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2013/262196 Open AccessAn eigensystem realization algorithm (ERA) approach for estimating the structural system matrices is proposed in this paper using the measurements of acceleration data available from the real crash test. A mathematical model that represents the real vehicle frontal crash scenario is presented. The model's structure is a double-spring-mass-damper system, whereby the front mass represents the vehicle-chassis and the rear mass represents the passenger compartment. The physical parameters of the model are estimated using curve-fitting approach, and the estimated state system matrices are estimated by using the ERA approach. The model is validated by comparing the results from the model with those from the real crash test

Application of Genetic Algorithm on Parameter Optimization of Three Vehicle Crash Scenarios

This paper focuses on the development of mathematical models for vehicle frontal crashes. The models under consideration are threefold: a vehicle into barrier, vehicle-occupant and vehicle to vehicle frontal crashes. The first model is represented as a simple spring-mass-damper and the second case consists of a double-spring-mass-damper system, whereby the front mass and the rear mass represent the vehicle chassis and the occupant, respectively. The third model consists of a collision of two vehicles represented by two masses moving in opposite directions. The springs and dampers in the models are nonlinear piecewise functions of displacements and velocities respectively. More specifically, a genetic algorithm (GA) approach is proposed for estimating the parameters of vehicles front structure and restraint system for vehicle-occupant model. Finally, using the existing test-data, it is shown that the obtained models can accurately reproduce the real crash test data

Oil whip-induced wear in journal bearings

Published version of an article in the journal: International Journal of Advanced Manufacturing Technology. Also available from the publisher at: http://dx.doi.org/10.1007/s00170-014-5805-8This paper investigates the effect of oil whirl and oil whip in fluid film radial bearings due to possible metallic contact. The degree of metallic contact and thereby wear and tear between rotating shafts and bearing bushes is assessed by measuring electric currents through the oil film. The current as well as the voltage varied in accordance with the contact ratio between the shaft and bush in the fluid film radial bearing. The gauge signal thus indicates the degree of metallic contact based on the thickness of the oil film in the load zone. Some experimental results are provided to illustrate that at low normalised loads involving oil whirl and oil whip, no electric current is detected, while high levels of electric current are registered at high load levels when no oil whirl or oil whip occurred. It is therefore concluded that at low loads, oil whirl and oil whip have little influence on wear and tear in a journal bearing

Analyse av utviklingsprosessen ved en typisk norsk lystbåtprodusent

Rapporten beskriver kartlegging av produktutviklingsprosessen ved en bedrift lokalisert på Sørlandet, GrimstadBåt AS (GB). Dette er et fiktivt navn på en båtprodusent lokalisert på sørlandet og rapporten baserer seg på intervjuer med bedriftens nøkkelpersoner i produktutviklingsprosessen. Det faglige grunnlaget er nedfelt i UNIC-prosjektets manual [1,2]. Rapporten vektlegger flaskehalser i utviklingsprosessen og at GB ikke legger tilstrekkelig vekt på den effektivisering av produksjon og produktutvikling (PU) som skjer hos konkurrentene Rapporten beskriver bedriften og en analyse av bedriftens produktutviklingsstrategi

Signal analysis and performance evaluation of a vehicle crash test with a fixed safety barrier based on Haar wavelets

This paper deals with the wavelet-based performance analysis of the safety barrier for use in a full-scale test. The test involves a vehicle, a Ford Fiesta, which strikes the safety barrier at a prescribed angle and speed. The vehicle speed before the collision was measured. Vehicle accelerations in three directions at the center of gravity were measured during the collision. The yaw rate was measured with a gyro meter. Using normal speed and high-speed video cameras, the behavior of the safety barrier and the test vehicle during the collision was recorded. Based upon the results obtained, the tested safety barrier has proved to satisfy the requirements for an impact severity level. By taking into account the Haar wavelets, the property of integral operational matrix is utilized to find an algebraic representation form for calculate of wavelet coefficients of acceleration signals. It is shown that Haar wavelets can construct the acceleration signals well

Investigation of vehicle crash modeling techniques: theory and application

Creating a mathematical model of a vehicle crash is a task which involves considerations and analysis of different areas which need to be addressed because of the mathematical complexity of a crash event representation. Therefore, to simplify the analysis and enhance the modeling process, in this work, a brief overview of different vehicle crash modeling methodologies is proposed. The acceleration of a colliding vehicle is measured in its center of gravity—this crash pulse contains detailed information about vehicle behavior throughout a collision. A virtual model of a collision scenario is established in order to provide an additional data set further used to evaluate a suggested approach. Three different approaches are discussed here: lumped parameter modeling of viscoelastic systems, data-based approach taking advantage of neural networks and autoregressive models and wavelet-based method of signal reconstruction. The comparative analysis between each method’s outcomes is performed and reliability of the proposed methodologies and tools is evaluated