Ba-DOPED ZnO MATERIALS: A DFT SIMULATION TO INVESTIGATE THE DOPING EFFECT ON FERROELECTRICITY

ZnO is a semiconductor material largely employed in the development of several electronic and optical devices due to its unique electronic, optical, piezo-, ferroelectric and structural properties. This study evaluates the properties of Ba-doped wurtzite-ZnO using quantum mechanical simulations based on the Density Functional Theory (DFT) allied to hybrid functional B3LYP. The Ba-doping caused increase in lattice parameters and slight distortions at the unit cell angle in a wurtzite structure. In addition, the doping process presented decrease in the band-gap (Eg) at low percentages suggesting band-gap engineering. For low doping amounts, the wavelength characteristic was observed in the visible range; whereas, for middle and high doping amounts, the wavelength belongs to the Ultraviolet range. The Ba atoms also influence the ferroelectric property, which is improved linearly with the doping amount, except for doping at 100% or wurtzite-BaO. The ferroelectric results indicate the ZnO:Ba is an strong option to replace perovskite materials in ferroelectric and flash-type memory devices.

A comparison of electricity spot prices simulation using ARMA-GARCH and mean-reverting models

The aim of this work is to compare two families of mathematical models for their respective capability to capture the statistical properties of real electricity spot market time series. The first model family is ARMA-GARCH models and the second model family is mean-reverting Ornstein-Uhlenbeck models. These two models have been applied to two price series of Nordic Nord Pool spot market for electricity namely to the System prices and to the DenmarkW prices. The parameters of both models were calibrated from the real time series. After carrying out simulation with optimal models from both families we conclude that neither ARMA-GARCH models, nor conventional mean-reverting Ornstein-Uhlenbeck models, even when calibrated optimally with real electricity spot market price or return series, capture the statistical characteristics of the real series. But in the case of less spiky behavior (System prices), the mean-reverting Ornstein-Uhlenbeck model could be seen to partially succeeded in this task.

Autosimulaattoripeleihin soveltuvan kaksiakselisen liikealustan kehittäminen

Työssä kehitettiin kohtuuhintainen ja suorituskyvyltään riittävä autosimulaattoripelikäyttöön soveltuva liikealusta. Työssä tutustuttiin aluksi markkinoilla oleviin liikealustaratkaisuihin. Työssä selvitettiin myös liikealustaa koskevia turvallisuusmääräyksiä. Kehittäminen alkoi liikealustan vaatimusten määrittelyllä ja kuormituksien simuloinnilla. Runkorakenteet mitoitettiin kestämään simuloituja rasituksia. Liikealustan toimilaitteet valittiin simulointitulosten perusteella. Työssä suunniteltiin myös liikealustan ohjausjärjestelmä. Mekaanisien osien ja voimansiirron mitoittamisen jälkeen suoritettiin osien yksityiskohtainen suunnittelu. Alihankkijat valmistivat osat ja ne koottiin Älykkäiden koneiden laboratoriossa. Järjestelmän kokoamisen jälkeen viritettiin säätäjät ja testattiin liikealustan toimivuutta. Kehitettyä liikealustaa on käytetty muutamissa tapahtumissa. Asetetut tavoitteet saavutettiin ja liikealusta soveltuu kokemuksien perusteella hyvin rata-autosimulaattoripelien kanssa käytettäväksi.

A risk infection simulation model for fusarium head blight of wheat

Fusarium Head Blight (FHB) is a disease of great concern in wheat (Triticum aestivum). Due to its relatively narrow susceptible phase and environmental dependence, the pathosystem is suitable for modeling. In the present work, a mechanistic model for estimating an infection index of FHB was developed. The model is process-based driven by rates, rules and coefficients for estimating the dynamics of flowering, airborne inoculum density and infection frequency. The latter is a function of temperature during an infection event (IE), which is defined based on a combination of daily records of precipitation and mean relative humidity. The daily infection index is the product of the daily proportion of susceptible tissue available, infection frequency and spore cloud density. The model was evaluated with an independent dataset of epidemics recorded in experimental plots (five years and three planting dates) at Passo Fundo, Brazil. Four models that use different factors were tested, and results showed all were able to explain variation for disease incidence and severity. A model that uses a correction factor for extending host susceptibility and daily spore cloud density to account for post-flowering infections was the most accurate explaining 93% of the variation in disease severity and 69% of disease incidence according to regression analysis.

Models and applications for risk assessment and prediction of Asian soybean rust epidemics

Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed.

3D Stripixel Detectors Simulation

Solid-state silicon detectors have replaced conventional ones in almost all recent high-energy physics experiments. Pixel silicon sensors don't have any alternative in the area near the interaction point because of their high resolution and fast operation speed. However, present detectors hardly withstand high radiation doses. Forthcoming upgrade of the LHC in 2014 requires development of a new generation of pixel detectors which will be able to operate under ten times increased luminosity. A planar fabrication technique has some physical limitations; an improvement of the radiation hardness will reduce sensitivity of a detector. In that case a 3D pixel detector seems to be the most promising device which can overcome these difficulties. The objective of this work was to model a structure of the 3D stripixel detector and to simulate electrical characteristics of the device. Silvaco Atlas software has been used for these purposes. The structures of single and double sided dual column detectors with active edges were described using special command language. Simulations of these detectors have shown that electric field inside an active area has more uniform distribution in comparison to the planar structure. A smaller interelectrode space leads to a stronger field and also decreases the collection time. This makes the new type of detectors more radiation resistant. Other discovered advantages are the lower full depletion voltage and increased charge collection efficiency. So the 3D stripixel detectors have demonstrated improved characteristics and will be a suitable replacement for the planar ones.

Integration und Vermittlung landeskundlicher Inhalte im Fremdsprachenunterricht

Tämän väitöskirjatyön aiheena on maantuntemuksellisten sisältöjen integrointi ja välittäminen vieraan kielen opetuksessa. Maantuntemuksellisilla sisällöillä tarkoitetaan vieraan kielen opetuksessa ei-kielellisiä sisältöjä, jotka ylittävät pelkän kielitiedon, kieliopin ja sanaston, välittämisen rajat. Tutkimuskirjallisuudessa näitä ei-kielellisiä sisältöjä nimitetään monin eri tavoin, esimerkiksi maantuntemukseksi (Landeskunde), sosiokulttuurisiksi tiedoiksi ja taidoiksi (soziokulturelles Wissen) tai yksinkertaisesti kulttuuriksi (Kultur). Väitöskirjatyö jakautuu teoreettiseen kehykseen (luvut 1–4), julkaistujen artikkeleiden tutkimusmetodien ja tuloksien käsittelyyn (luvut 5–6) sekä julkaistuihin artikkeleihin. Teoreettisen kehyksen ensisijaisia tutkimuskysymyksiä ovat, miten maantuntemuksellisten sisältöjen välittäminen konkretisoituu eri näkökulmista (opettajat, oppijat, oppimateriaalit) tarkasteltuna, miten kulttuurienvälinen maantuntemus ilmentyy vieraan kielen opetuksessa ja mitkä sisällöt ovat merkittäviä vieraan kielen opetuksessa. Metodisina lähestymistapoina tutkimuksessa on käytetty oppikirja-analyysiä, opetuksen tarkkailua sekä kyselytutkimuksia. Liitteenä oleville julkaistuille artikkeleille on yhteistä se, että jokainen niistä käsittelee jotakin erityistä maantuntemuksellisiin sisältöihin liittyvää aihetta empiriisestä näkökulmasta erityisesti saksan kielen opetuksen kannalta. Artikkelien tutkimusongelmia ovat kulttuuristen ja kielellisten sisältöjen yhdistäminen, kulttuurienvälisen viestinnän konkretisoituminen, kielellisen ja kulttuurisen variaation huomioiminen, stereotyyppien asema sekä sukupuolierojen merkitys vieraan kielen opetuksessa. Väitöskirjatyön teoreettisessa kehyksessä luodaan aluksi historiallinen katsaus maantuntemuksen asemaan vieraan kielen opetuksessa ja selvitetään tarkemmin erityisesti vieraan kielen didaktiikan uusimpien traditioiden, kuten konstruktivismin ja sosiokulttuurisen teorian, yhteyttä maantuntemuksen oppimiseen. Tässä yhteydessä käsitellään myös kulttuurienvälisen oppimisen traditiota ja maantuntemusta sen sovellusalueena. Tämän lisäksi selvitetään konkreettisia vieraan kielen opetuksessa ilmeneviä maantuntemukseen liittyviä didaktis-metodisia kysymyksiä, erityisesti opettajan roolia ja sitä, miten kulttuurienvälisen tradition mukainen maantuntemuksen välittäminen konkretisoituu yhtäältä yksittäisinä tehtävinä ja harjoituksina sekä toisaalta elektronisten viestimien välityksellä. Teoreettisen kehyksen ytimen muodostaa maantuntemuksellisten aiheiden valintaan ja merkittävyyteen liittyvä tutkimuskirjallisuuden pohjalta tehtävä pohdinta. Vieraan kielen opetuksessa kieliopilliset sisällöt opetetaan pääosin vakiintuneessa järjestyksessä, mutta maantuntemuksellisten sisältöjen opettamisessa ja oppimisessa ei ole säännönmukaisuuksia. Yhteenvetona esitetään teesejä, joiden tarkoituksena on antaa ehdotuksia, suosituksia ja didaktisia neuvoja maantuntemuksen opetukseen ja oppimiseen. Väitöskirjatyössä paneudutaan vaikeuksiin määritellä maantuntemuksen oppimisen kannalta merkittävät aiheet erityisesti saksan kielen opetusta silmällä pitäen. Arkipäivän kulttuurin käsittelyn tärkeyteen käytännön opetuksessa viittaavat oppikirjojen aihepiirit, opettajien ja opiskelijoiden käsitykset sekä Eurooppalaisen viitekehyksen suositukset. Tutkimuksessa selvitettiin tarkemmin myös aihepiirien valintaa kohderyhmän mukaan ja kartoitettiin oppijoiden käsityksiä maantuntemuksellisista sisällöistä ja heidän näihin kohdistuvia toiveitaan. Kyselytulosten mukaan aikuisten oppijoiden mieliin jäivät saksan kielen oppitunnilla erityisesti sellaiset kulttuuriin liittyvät asiat, jotka oppijat kokivat autenttisiksi tai jotka herättivät tunnilla keskustelua ja olivat kohdekulttuurissa erilaisia kuin omassa kulttuurissa. Tutkimuksessa selvitettiin myös kulttuurienvälisen oppimisen aspekteja vieraan kielen opetuksessa ja oppimateriaaleissa, erityisesti ”oman” ja ”vieraan” kulttuurin kokemisesta ja niiden vastakkainasettelusta. Näyttää siltä, että kulttuurienvälisen oppimisen mahdollisuudet tutkimissani saksan kielen oppikirjoissa rajoittuvat siihen, että oppijoille tarjotaan mahdollisuus eläytyä kohdekulttuurin arkeen oppikirjojen henkilöiden kautta ja että oppijoita kehotetaan kertomaan omasta kulttuuristaan. Tutkimuksessa pohditaan myös tarkemmin, voivatko sähköiset oppimateriaalit ja internet johtaa takaisin faktoihin keskittyvään maantuntemuksen oppimiseen. Virtuaaliset oppimisympäristöt, esimerkiksi oppikirjojen internetsivustot, antavat kaikesta huolimatta uusia mahdollisuuksia tutkivaan oppimiseen. Tällaisia ovat esimerkiksi ”minitutkimustehtävät” ja sellaiset harjoitustyypit, jotka eivät oppikirjoissa ole mahdollisia, kuten virtuaaliset kaupunkikierrokset. Opettajien ja oppimateriaalien laatijoiden pitäisi suunnitella sellaisia tehtäviä ja harjoituksia, jotka antavat riittävästi mahdollisuuksia myös kulttuurienväliselle pohdinnalle. Oppijan oma ja kohdekulttuuri voidaan opetuksessa nostaa samanaikaisesti esille esimerkiksi käsittelemällä kielellisiä ja kulttuurisia variaatioita. Tutkimustulosten mukaan kulttuurienvälisen oppimisen traditionkin aikana maantuntemusta välitetään yhä perinteisellä tavalla faktatietoihin painottuen, eli käytännössä kieltenopetusta ohjaa vielä edelleenkin hyvin perinteinen käsitys kielestä ja kielitaidosta. Kielten opettajien koulutuksessa olisi huomioitava se, että opettajien tulisi olla kokonaisvaltaisia kulttuurin asiantuntijoita, eli myös historia, yhteiskunta, politiikka ja myös ”arkipäiväisen elämän” tuntemus ovat tärkeitä opettajan ammattitaidossa.

Induction Motor Drive Energy Efficiency - Simulation and Analysis

A coupled system simulator, based on analytical circuit equations and a finite element method (FEM) model of the motor has been developed and it is used to analyse a frequency-converterfed industrial squirrel-cage induction motor. Two control systems that emulate the behaviour of commercial direct-torque-controlled (DTC) and vector-controlled industrial frequency converters have been studied, implemented in the simulation software and verified by extensive laboratory tests. Numerous factors that affect the operation of a variable speed drive (VSD) and its energy efficiency have been investigated, and their significance in the simulation of the VSD results has been studied. The dependency of the frequency converter, induction motor and system losses on the switching frequency is investigated by simulations and measurements at different speeds for both the vector control and the DTC. Intensive laboratory measurements have been carried out to verify the simulation results.

Integration of the Food Waste Disposer Unit to the Existing Sewage System

Among the numerous approaches to food waste treatment, the food waste disposers method (FWDs), as a newcomer, has become slowly accepted by the general public owing to the worries about its impact on the existing sewage system. This paper aims to justify the role of FWDs in the process of urbanization in order to better prepare a city to take good care of the construction of its infrastructure and the solid waste treatment. Both the literatures and the case study help to confirm that FWDs has no negative effects on the wastewater treatment plant and it is also environmental friendly by reducing the greenhouse gas emissions. In the case study, the Lappeenranta waste water treatment plant has been selected in order to figure out the possible changes to a WWTP following the integration of FWDs: the observation shows only minor changes take place in a WWTP, in case of 25% application, like BOD up 7%, TSS up 6% and wastewater flowrate up 6%, an additional sludge production of 200 tons per year and the extra yield of methane up to 10000m3 per year; however, when the utilization rate of FWD is over 75%, BOD, TSS, and wastewater flowrate will experience more significant changes, thus exerting much pressure on the existing WWTP. FWDs can only be used in residential areas or cities equipped with consummate drainage network within the service sphere of WWTP, therefore, the relevant authority or government department should regulate the installation frequency of FWDs, while promoting the accessory application of FWDs. In the meanwhile, WWTP should improve their treatment process in order to expand their capacity for sludge treatment so as to stay in line with the future development of urban waste management.

CFD Simulation of Two-phase and Three-phase Flows in Internal-loop Airlift

Airlift reactors are pneumatically agitated reactors that have been widely used in chemical, petrochemical, and bioprocess industries, such as fermentation and wastewater treatment. Computational Fluid Dynamics (CFD) has become more popular approach for design, scale-up and performance evaluation of such reactors. In the present work numerical simulations for internal-loop airlift reactors were performed using the transient Eulerian model with CFD package, ANSYS Fluent 12.1. The turbulence in the liquid phase is described using κ- ε the model. Global hydrodynamic parameters like gas holdup, gas velocity and liquid velocity have been investigated for a range of superficial gas velocities, both with 2D and 3D simulations. Moreover, the study of geometry and scale influence on the reactor have been considered. The results suggest that both, geometry and scale have significant effects on the hydrodynamic parameters, which may have substantial effects on the reactor performance. Grid refinement and time-step size effect have been discussed. Numerical calculations with gas-liquid-solid three-phase flow system have been carried out to investigate the effect of solid loading, solid particle size and solid density on the hydrodynamic characteristics of internal loop airlift reactor with different superficial gas velocities. It was observed that averaged gas holdup is significantly decreased with increasing slurry concentration. Simulations show that the riser gas holdup decreases with increase in solid particle diameter. In addition, it was found that the averaged solid holdup increases in the riser section with the increase of solid density. These produced results reveal that CFD have excellent potential to simulate two-phase and three-phase flow system.

Simulation of hydrogen peroxide direct synthesis in a microreactor

A set of models in Aspen plus was built to simulate the direct synthesis process of hydrogen peroxide in a micro-reactor system. This process model can be used to carry out material balance calculation under various experimental conditions. Three thermodynamic property methods were compared by calculating gas solubility and Uniquac-RK method was finally selected for process model. Two different operation modes with corresponding operation conditions were proposed as the starting point of future experiments. Simulations for these two modes were carried out to get the information of material streams. Moreover, some hydrodynamic parameters such as gas/liquid superficial velocity, gas holdup were also calculated with improved process model. These parameters proved the proposed experimental conditions reasonable to some extent. The influence of operation conditions including temperature, pressure and circulation ratio was analyzed for the first operation mode, where pure oxygen was fed into dissolving tank and hydrogen-carbon dioxide mixture was fed into microreactor directly. The preferred operation conditions for the system are low temperature (2°C) and high pressure (30 bar) in dissolving tank. High circulation ratio might be good in the sense that more oxygen could be dissolved and fed into reactor for reactions, but meanwhile hydrodynamics of microreactor should be considered. Furthermore, more operation conditions of reactor gas/liquid feeds in both of two operation modes were proposed to provide guidance for future experiment design and corresponding hydrodynamic parameters were also calculated. Finally, safety issue was considered from thermodynamic point of view and there is no explosion danger at given experimental plan since the released reaction heat will not cause solvent vaporization inside the microchannels. The improvement of process model still needs further study based on the future experimental results.

Microscopic simulation of pigment coating consolidation

The control of coating layer properties is becoming increasingly important as a result of an emerging demand for novel coated paper-based products and an increasing popularity of new coating application methods. The governing mechanisms of microstructure formation dynamics during consolidation and drying are nevertheless, still poorly understood. Some of the difficulties encountered by experimental methods can be overcome by the utilisation of numerical modelling and simulation-based studies of the consolidation process. The objective of this study was to improve the fundamental understanding of pigment coating consolidation and structure formation mechanisms taking place on the microscopic level. Furthermore, it is aimed to relate the impact of process and suspension properties to the microstructure of the coating layer. A mathematical model based on a modified Stokesian dynamics particle simulation technique was developed and applied in several studies of consolidation-related phenomena. The model includes particle-particle and particle-boundary hydrodynamics, colloidal interactions, Born repulsion, and a steric repulsion model. The Brownian motion and a free surface model were incorporated to enable the specific investigation of consolidation and drying. Filter cake stability was simulated in various particle systems, and subjected to a range of base substrate absorption rates and system temperatures. The stability of the filter cake was primarily affected by the absorption rate and size of particles. Temperature was also shown to have an influence. The consolidation of polydisperse systems, with varying wet coating thicknesses, was studied using imposed pilot trial and model-based drying conditions. The results show that drying methods have a clear influence on the microstructure development, on small particle distributions in the coating layer and also on the mobility of particles during consolidation. It is concluded that colloidal properties can significantly impact coating layer shrinkage as well as the internal solids concentration profile. Visualisations of particle system development in time and comparison of systems at different conditions are useful in illustrating coating layer structure formation mechanisms. The results aid in understanding the underlying mechanisms of pigment coating layer consolidation. Guidance is given regarding the relationship between coating process conditions and internal coating slurry properties and their effects on the microstructure of the coating.

Tutorials for MeVEA Simulation Software

The objective of the thesis was to create three tutorials for MeVEA Simulation Software to instruct the new users to the modeling methodology used in the MeVEA Simulation Software. MeVEA Simulation Software is a real-time simulation software based on multibody dynamics. The simulation software is designed to create simulation models of complete mechatronical system. The thesis begins with a more detail description of the MeVEA Simulation Software and its components. The thesis presents the three simulation models and written theory of the steps of model creation. The first tutorial introduces the basic features which are used in most simulation models. The basic features include bodies, constrains, forces, basic hydraulics and motors. The second tutorial introduces the power transmission components, tyres and user input definitions for the different components in power transmission systems. The third tutorial introduces the definitions of two different types of collisions and collision graphics used in MeVEA Simulation Software.

Adherence and perceptions regarding simulation training in undergraduate health Sciences

BACKGROUND: Simulation techniques are spreading rapidly in medicine. Suc h resources are increasingly concentrated in Simulation Laboratories. The MSRP-USP is structuring such a laboratory and is interested in the prevalence of individual initiatives that could be centralized there. The MSRP-USP currently has five full-curriculum courses in the health sciences: Medicine, Speech Therapy, Physical Therapy, Nutrition, and Occupational Therapy, all consisting of core disciplines. GOAL: To determine the prevalence of simulation techniques in the regular courses at MSRP-USP. METHODS: Coordinators of disciplines in the various courses were interviewed using a specifically designed semi-structured questionnaire, and all the collected data were stored in a dedicated database. The disciplines were grouped according to whether they used (GI) or did not use (GII) simulation resources. RESULTS AND DISCUSSION: 256 disciplines were analyzed, of which only 18.3% used simulation techniques, varying according to course: Medicine (24.7.3%), Occupational Therapy (23.0%), Nutrition (15.9%), Physical Therapy (9.8%), and Speech Therapy (9.1%). Computer simulation programs predominated (42.5%) in all five courses. The resources were provided mainly by MSRP-USP (56.3%), with additional funding coming from other sources based on individual initiatives. The same pattern was observed for maintenance. There was great interest in centralizing the resources in the new Simulation Laboratory in order to facilitate maintenance, but there was concern about training and access to the material. CONCLUSIONS: 1) The MSRP-USP simulation resources show low complexity and are mainly limited to computer programs; 2) Use of simulation varies according to course, and is most prevalent in Medicine; 3) Resources are scattered across several locations, and their acquisition and maintenance depend on individual initiatives rather than central coordination or curricular guidelines

Teoretiskt om invandrares integration

Kirjallisuusarvostelu