Svjetlovodni senzor za mjerenje vibracija

Radom je obuhvaćen razvoj idejnog rješenja i prototipa svjetlovodnog senzora za mjerenje vibracija na osnovi zahtjeva iz projekta pod nazivom “Konstrukcija i izrada prototipa svjetlovodnog senzora za mjerenje vibracija za daljinski nadzor električnih strojeva velikih snaga” koji se provodi na Fakultetu elektrotehnike i računarstva (FER) u Zagrebu. U prvom dijelu rada prikazane su teorijske osnove iz područja optike te su napravljena dva analitička proračuna optičkih značajki senzora u svrhu određivanja maksimalne dozvoljene amplitude pomaka vibrirajuće membrane kao ulaznog podataka u proračun mehaničkih vibracija. Potvrda ispravnosti analitičkih optičkih proračuna dobivena je numeričkom simulacijom tog problema u komercijalnom računalnom programu ZEMAX (licenca FER). U sklopu rada razvijen je poseban programski kod u softverskom paketu MATLAB s ciljem optimizacije mehaničkih komponenti svjetlovodnog senzora. Kod se temelji na analitičkim matematičkim modelima, koji su također u okviru diplomskog rada detaljno razrađeni. Na osnovi podataka iz optičkog proračuna provjereni su načini vibriranja više izvedbi senzora korištenjem razvijenog koda te su preliminarno optimirane dimenzije senzora. Provjera rezultata dobivenih MATLAB kodom učinjena je usporedbom s rezultatima dinamičke analize metodom konačnih elemenata u softverskom paketu FEMAP / NASTRAN za različita idejna rješenja. Temeljem provedenih analiza određene su optimalne dimenzije mehaničkih dijelova senzora. Temeljem ukupnih dobivenih rezultata osmišljeno je konstrukcijsko rješenje te su propisani materijali i tehnologija izrade svih mehaničkih dijelova prototipa senzora uvažavajući ograničenja koja proizlaze iz područja primjene senzora te financijska ograničenja. U tekstu se nalazi detaljan opis konstrukcije uz priložene radioničke crteže. Prototip je izrađen tehnologijom 3D printanja i prikazan na kraju rada. Na samom kraju ispitan je utjecaj otpora okolnog zraka na vibracije membrane primjenom računalne dinamike fluida (CFD)

Postupak umjravanja pretvornika tlaka visokog razreda točnosti

U radu je prikazan postupak umjeravanja mjerila tlaka po preporuci DKD-R6-1 Guideline (Calibration of Pressure Gauges) s posebnim naglaskom na umjeravanje pretvornika tlaka visokog razreda točnosti po A tipu procedure umjeravanja. U sklopu rada provedeno je umjeravanje pretvornika tlaka (PDCR 2200 - 1939) indikacije do 350 bara na etalonskoj tlačnoj vagi ''Pressurements'' (TLVAG-08) u Laboratoriju za procesna mjerenja Fakulteta strojarstva i brodogradnje, a dobiveni rezultati obrađeni su u računalnom programu Excel. U uvodnom dijelu rada prikazan je općeniti postupak određivanja mjerne nesigurnosti ISO-GUM metodom te je, također u sklopu uvodnog dijela, riješen jedan općeniti primjer procjene mjerne nesigurnosti

Fibre-optic sensor for vibrations measurement

Radom je obuhvaćen razvoj idejnog rješenja i prototipa svjetlovodnog senzora za mjerenje vibracija na osnovi zahtjeva iz projekta pod nazivom “Konstrukcija i izrada prototipa svjetlovodnog senzora za mjerenje vibracija za daljinski nadzor električnih strojeva velikih snaga” koji se provodi na Fakultetu elektrotehnike i računarstva (FER) u Zagrebu. U prvom dijelu rada prikazane su teorijske osnove iz područja optike te su napravljena dva analitička proračuna optičkih značajki senzora u svrhu određivanja maksimalne dozvoljene amplitude pomaka vibrirajuće membrane kao ulaznog podataka u proračun mehaničkih vibracija. Potvrda ispravnosti analitičkih optičkih proračuna dobivena je numeričkom simulacijom tog problema u komercijalnom računalnom programu ZEMAX (licenca FER). U sklopu rada razvijen je poseban programski kod u softverskom paketu MATLAB s ciljem optimizacije mehaničkih komponenti svjetlovodnog senzora. Kod se temelji na analitičkim matematičkim modelima, koji su također u okviru diplomskog rada detaljno razrađeni. Na osnovi podataka iz optičkog proračuna provjereni su načini vibriranja više izvedbi senzora korištenjem razvijenog koda te su preliminarno optimirane dimenzije senzora. Provjera rezultata dobivenih MATLAB kodom učinjena je usporedbom s rezultatima dinamičke analize metodom konačnih elemenata u softverskom paketu FEMAP / NASTRAN za različita idejna rješenja. Temeljem provedenih analiza određene su optimalne dimenzije mehaničkih dijelova senzora. Temeljem ukupnih dobivenih rezultata osmišljeno je konstrukcijsko rješenje te su propisani materijali i tehnologija izrade svih mehaničkih dijelova prototipa senzora uvažavajući ograničenja koja proizlaze iz područja primjene senzora te financijska ograničenja. U tekstu se nalazi detaljan opis konstrukcije uz priložene radioničke crteže. Prototip je izrađen tehnologijom 3D printanja i prikazan na kraju rada. Na samom kraju ispitan je utjecaj otpora okolnog zraka na vibracije membrane primjenom računalne dinamike fluida (CFD).This thesis deals with the conceptual design and prototype development of a fiber optic sensor for measuring vibrations. The requests and working conditions for this sensor are given in a project which is being carried out at the Faculty of Electrical Engineering and Computing (FER) in Zagreb, named “Designing and production of a fiber optic sensor for measuring vibrations in remote monitoring of high-powered electrical machinery”. First part of the thesis shows theoretical basis of optical measurements and also consists of analytical calculations of sensor’s optical characteristics in order to determine the maximal allowable amplitude of membrane’s vibrations. The computed amplitude is then used as input data in further calculations of mechanical vibrations. In addition, numerical simulations of the problem carried out in commercial software package ZEMAX (licensed to FER) were used to confirm the accuracy of optical analytical calculations. As part of the thesis, a specific program code was developed in MATLAB software package in order to optimize the mechanical components of fiber optic sensor. The developed program code is based on analytical mathematical models, which are also elaborated within this thesis. Using the program code, various implementations of sensor and their different vibrating modes were examined on the basis of optical calculations data. Additionally, preliminary dimensions of the sensor were established at this stage. For several different conceptual designs, control of results obtained by the MATLAB code was done by comparing them with results of dynamic finite element analysis in FEMAP / NASTRAN software package. In regard to conducted analysis, optimal dimensions of sensor’s mechanical parts were determined. A structural solution for the sensor was designed according to overall results. Materials and production technologies for all of prototype sensor’s mechanical parts were defined by taking into account financial constraints and the constraints arising from sensor’s area of application. The paper contains a detailed description of the design and the accompanying manufacturing sheets and drawings. The prototype was made using 3D printing technology and its images can be seen in penultimate chapter of this paper. Finally, effect of drag (from the surrounding air) on vibrations of the membrane was investigated using computational fluid dynamics (CFD)

Ship resistance when operating in floating ice floes: a combined CFD&DEM approach

Whilst climate change is transforming the Arctic into a navigable ocean where small ice floes are floating on the sea surface, the effect of such ice conditions on ship performance has yet to be understood. The present work combines a set of numerical methods to simulate the ship-wave-ice interaction in such ice conditions. Particularly, Computational Fluid Dynamics is applied to provide fluid solutions for the floes and it is incorporated with the Discrete Element Method to govern ice motions and account for ship-ice/ice-ice collisions, by which, the proposed approach innovatively includes wave effects in the interaction. In addition, this work introduces two algorithms that can implement computational models with natural ice-floe fields, which takes randomness into consideration thus achieving high-fidelity modelling of the problem. Following validation against experiments, the model is shown accurate in predicting the ice-floe resistance of a ship, and then a series of simulations are performed to investigate how the resistance is influenced by ship speed, ice concentration, ice thickness and floe diameter. This paper presents a useful approach that can provide power estimates for Arctic shipping and has the potential to facilitate other polar engineering purposes.Comment: 26 pages 18 figures, submitted journal pape

Fibre-optic sensor for vibrations measurement

Radom je obuhvaćen razvoj idejnog rješenja i prototipa svjetlovodnog senzora za mjerenje vibracija na osnovi zahtjeva iz projekta pod nazivom “Konstrukcija i izrada prototipa svjetlovodnog senzora za mjerenje vibracija za daljinski nadzor električnih strojeva velikih snaga” koji se provodi na Fakultetu elektrotehnike i računarstva (FER) u Zagrebu. U prvom dijelu rada prikazane su teorijske osnove iz područja optike te su napravljena dva analitička proračuna optičkih značajki senzora u svrhu određivanja maksimalne dozvoljene amplitude pomaka vibrirajuće membrane kao ulaznog podataka u proračun mehaničkih vibracija. Potvrda ispravnosti analitičkih optičkih proračuna dobivena je numeričkom simulacijom tog problema u komercijalnom računalnom programu ZEMAX (licenca FER). U sklopu rada razvijen je poseban programski kod u softverskom paketu MATLAB s ciljem optimizacije mehaničkih komponenti svjetlovodnog senzora. Kod se temelji na analitičkim matematičkim modelima, koji su također u okviru diplomskog rada detaljno razrađeni. Na osnovi podataka iz optičkog proračuna provjereni su načini vibriranja više izvedbi senzora korištenjem razvijenog koda te su preliminarno optimirane dimenzije senzora. Provjera rezultata dobivenih MATLAB kodom učinjena je usporedbom s rezultatima dinamičke analize metodom konačnih elemenata u softverskom paketu FEMAP / NASTRAN za različita idejna rješenja. Temeljem provedenih analiza određene su optimalne dimenzije mehaničkih dijelova senzora. Temeljem ukupnih dobivenih rezultata osmišljeno je konstrukcijsko rješenje te su propisani materijali i tehnologija izrade svih mehaničkih dijelova prototipa senzora uvažavajući ograničenja koja proizlaze iz područja primjene senzora te financijska ograničenja. U tekstu se nalazi detaljan opis konstrukcije uz priložene radioničke crteže. Prototip je izrađen tehnologijom 3D printanja i prikazan na kraju rada. Na samom kraju ispitan je utjecaj otpora okolnog zraka na vibracije membrane primjenom računalne dinamike fluida (CFD).This thesis deals with the conceptual design and prototype development of a fiber optic sensor for measuring vibrations. The requests and working conditions for this sensor are given in a project which is being carried out at the Faculty of Electrical Engineering and Computing (FER) in Zagreb, named “Designing and production of a fiber optic sensor for measuring vibrations in remote monitoring of high-powered electrical machinery”. First part of the thesis shows theoretical basis of optical measurements and also consists of analytical calculations of sensor’s optical characteristics in order to determine the maximal allowable amplitude of membrane’s vibrations. The computed amplitude is then used as input data in further calculations of mechanical vibrations. In addition, numerical simulations of the problem carried out in commercial software package ZEMAX (licensed to FER) were used to confirm the accuracy of optical analytical calculations. As part of the thesis, a specific program code was developed in MATLAB software package in order to optimize the mechanical components of fiber optic sensor. The developed program code is based on analytical mathematical models, which are also elaborated within this thesis. Using the program code, various implementations of sensor and their different vibrating modes were examined on the basis of optical calculations data. Additionally, preliminary dimensions of the sensor were established at this stage. For several different conceptual designs, control of results obtained by the MATLAB code was done by comparing them with results of dynamic finite element analysis in FEMAP / NASTRAN software package. In regard to conducted analysis, optimal dimensions of sensor’s mechanical parts were determined. A structural solution for the sensor was designed according to overall results. Materials and production technologies for all of prototype sensor’s mechanical parts were defined by taking into account financial constraints and the constraints arising from sensor’s area of application. The paper contains a detailed description of the design and the accompanying manufacturing sheets and drawings. The prototype was made using 3D printing technology and its images can be seen in penultimate chapter of this paper. Finally, effect of drag (from the surrounding air) on vibrations of the membrane was investigated using computational fluid dynamics (CFD)

Negative-Inertia Converters: Devices Manifesting Negative Mass and Negative Moment of Inertia

Negative inertia is an unusual and counter-intuitive property of matter, extensively investigated in some of the most exotic branches of physics and engineering at both macroscopic and microscopic levels. Such an exotic property promises a wide range of applications, from Alcubierre drive to acoustic wave manipulation. Here, a novel approach to the realization of negative inertia and the concept of negative-inertia converters are introduced for both translational and rotational motion. The proposed devices, capable of exhibiting negative mass and negative moment of inertia, base their operational principle on actuating the loading inertia, concealed within the housing of the device, synchronously with the displacement of the housing itself. Negative-inertia converters share many similarities with negative-impedance converters, including their proneness to instability. Thus, an equivalent circuit model of the proposed devices is developed and simulated in lossless and lossy environments. Friction, unavoidable in every practical system, is found to be the main cause of instability. The derived closed-form stability condition suggests that the effective inertia of a system containing a negative-inertia converter must remain positive to ensure the stability. Despite this limitation, negative-inertia converters may become the key elements in applications requiring reduction of an object’s inertia

New tools to generate realistic ice floe fields for computational models

Global warming has extensively transformed Arctic sea ice from continuous level ice coverage to unconsolidated ice floe fields. Whilst the ice floes have a mixture of different sizes and their locations are randomly distributed, contemporary computational models lack effective methods to generate floe fields with such a natural pattern. This work introduces two original tools that can generate realistic ice floe fields for computational models. They are a sequential generator that sequentially handles ice floes one by one, and a genetic generator based upon a genetic algorithm. Demonstration of the tools is given, presenting samples of generating various shapes of floes and arbitrary mixtures of different shapes. Furthermore, an example is provided that combines the generated floe field with computational work modelling a ship transiting in ice floes. In addition, the source code of the tools is sharable with the public

Design of synchronous reluctance generator with dual stator windings and anisotropic rotor with flux barriers

Appropriate design of synchronous reluctance machine with dual stator winding and anisotropic rotor with flux barriers in generator operation mode is investigated. Finite element analysis is employed in order to determine the machine performance. Two different designs for synchronous reluctance generator with dual stator windings and the same anisotropic rotor with flux barrier are presented

Impact of saturation modelling on the losses of electric drive controlled by QFT

The aim of this paper is to present the impact of magnetic nonlinearities and saturation on the losses of an electric drive controlled by Quantitative Feedback Theory. For exact analysis of losses three magnetically different types of series wound DC motor dynamic models are presented and used in this work. As its main contribution this study shows that the modelling of magnetic nonlinearities improves control synthesis of electrical drive, which is reflected in lower energy consumption. For the purpose of control design of series wound DC motor Quantitative Feedback Theory was used