Browsing by Department "Department of Electronics"

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An Arrangement to Locate and Identify People with Dual-Frequency Tags Providing Context-Related Information
(2012) Ropponen, Antti
School of Electrical Engineering | Doctoral dissertation (article-based)
The demographic dependency ratio is changing in the industrialized countries, because the proportion of senior citizens is growing. An electric sensor with intelligence (ELSI) system was developed to monitor and locate patients, which helps the caring personnel and upgrades the service. The system has been used in many care homes for the elderly in Finland and has proved its benefits for the patients and staff. The problem with the ELSI system was that it could not identify the people it located. Additionally, the alarm devices that were used were impractical. Hence a dual-band localization system was introduced to address these deficiencies. The dual-band system uses active tags that are located with an antenna matrix embedded into the ELSI floor. The tag communicates with the ELSI system using a ZigBee network. The tag also has a display, and thus it can be used to show short alarms. Furthermore, an outline of a more versatile alarm and information system is introduced, with a multifunctional name tag concept. The system introduced here was demonstrated with a pilot installation which consisted of the ELSI and the dual-band system. It was shown that the system can locate and identify people with an accuracy of 0.64 m ± 0.31 m (S.D.). The accuracy can even be improved if the data are combined with the ELSI localization information. It was also shown with measurements that the localization method can be considered to be robust, because the LF signal penetrates nearly all normal objects.
Detection of human movement by near field imaging : development of a novel method and applications
(2011) Rimminen, Henry
Aalto-yliopiston teknillinen korkeakoulu | Doctoral dissertation (article-based)
The proportion of senior citizens is increasing, which requires more resources in the care services. The effectiveness of these services is proposed to be increased by remote monitoring of senior citizens living at home or in nursing homes. The monitoring can be performed with various types of sensors, but the solution presented here incorporates most of the functionalities found in related work in one comprehensive system. The system that was developed uses electric field sensing to detect human presence and movement. Falls and the vital functions of a fallen person can also be extracted from the signals. The sensor arrangement consists of a matrix of thin planar electrodes under the floor surface, which makes the system completely undetectable and discreet. It is not disturbed by shading or darkness and does not require a lot of computing power. Computer vision does not enjoy these advantages. Furthermore, no devices need to be worn and no batteries need to be charged, as with systems based on transponders worn by the subject. If identification is required, the system developed in this work does not rule out the use of transponders. The impedances of the electrodes are measured using a tuned transformer and a phase-sensitive detector. A signal-to-noise ratio of 37 dB has been achieved with this structure. The mean positioning error when observing people who are walking is 21 cm. Multiple people can be discriminated with a 90% certainty if the distance between them is 78 cm. The sensitivity and specificity in fall detection have been found to be 91% and 91%, respectively. The cardiac activity and respiration are clearly visible when a person lies prone or supine on the floor. A capacitive radio frequency identification (RFID) tag in a shoe was developed for person identification. The system developed here has been installed in a large nursing home. The nurses have indicated their satisfaction in a comprehensive questionnaire, which was conducted by a representative of the nurses. Positive feedback has also been obtained from a senior person living alone and from his family members.
Development and analysis of road lighting : road surfaces and mesopic dimensioning
(2011) Ylinen, Anne-Mari
Sähkötekniikan korkeakoulu | Doctoral dissertation (article-based)
This work starts with a short introduction in which the energy consumption, proportion of different types of light sources, and procedures that have been introduced concerning energy saving in outdoor lighting are overviewed. It is followed by a historical review and research related to aspects of the topic referred to in this work: the luminance method used for photometric dimensioning of road lighting, road surface classification practises, and mesopic photometry. The work continues with a study of road surface reflection characteristics. Road surface reflection measurements were made to study the current state of the pavement materials used on Finnish roads. Pavement samples were extracted from roads and the reflection tables of the pavement samples were measured. The pavement materials used in Finland are somewhat dark and diffuse and the standard reflection tables give an adequate fit for the degree of specularity but not for the degree of lightness. The spectral reflection properties of various types and differently coloured pavement samples were studied. The results indicate that light sources that have a higher spectral light output in the longer wavelength region, such as high pressure sodium lamps, are more energy-efficient in terms of light reflected from the pavements compared to the ones with a high output in the short wavelength region. In addition, pavement materials made out of recycled materials and local limestone were studied. Light pavement materials reflect more light than darker pavement materials, and energy could be saved by increasing the spacing of the poles for the luminaires or reducing the power consumption of the luminaires. The work continues with a study of mesopic dimensioning in road lighting. The luminous efficacy of various types of luminaires and the use of mesopic dimensioning in road lighting design were studied. The study is followed by a case study where high pressure sodium lamp street lighting was changed to LED street lighting. The energy consumption of the installation was calculated and mesopic dimensioning was used. The results show that energy savings are possible when mesopic dimensioning is used by reducing the power consumption of the luminaire or by increasing the spacing of the poles for the luminaires. The work continues by studying the differences in using the standard r-tables and the measured r-tables of the pavement used in the road lightning design on Finnish roads. It was found that the R2 table should be used for road lighting design if the reflection property of the pavement is not known. The work is followed by a study of the use of light pavement materials and mesopic dimensioning. In this case the benefits of mesopic dimensioning are negligible when light pavement materials are used.
Development and enhancement of road lighting principles
(2010) Ekrias, Aleksanteri
Aalto-yliopiston teknillinen korkeakoulu | Doctoral dissertation (article-based)
The work starts with a short introduction concerning the history of road lighting, outlining the trends and changes that have taken place in road lighting research during the past century. The introduction is followed by a review of trends, directions, and problems in current road lighting research and practice. The following part of the work introduces an advanced approach to road lighting measurements and calculations, based on the use of an imaging luminance photometer and the Road LumiMeter v2.0 computer program. The work sets out to investigate the variations in the characteristics of the quality of the road lighting at the same pilot locations in relation to the calculation methods used. In the work mesopic visual performance and the effects of the spectral transmittance of the vehicle windshield on the visibility conditions of the driver are also analysed. The work continues with road lighting measurements in various weather conditions in order to study the effects of snowy and wet road surface conditions on road lighting luminances. The results show that in Finland, snowy conditions offer very good opportunities to save electricity without adversely affecting either the safety of driving or the quality of road lighting. The following measurements set out to investigate the contribution of halogen and high-intensity discharge headlights to road lighting and whether this has a conflicting effect on the luminance contrasts of various targets located on the road or at the side of the road. The results indicate that, in general, the use of vehicle headlights in the presence of road lighting reduces the luminance contrasts of targets. The work continues with road lighting visibility experiments which study the visibility of achromatic and coloured targets in MH lamp and HPS lamp installations. The results show that colours have a major effect on target visibility if the road is illuminated with a light source with adequate colour rendering properties. Finally, pavement sample measurements are made to study the effects of aggregate lightness and aggregate colour on the reflectance properties of pavements. HPS lamps are found to be more effective than MH lamps in terms of light reflected from pavements.
Amperometric measurement of glutamate
(2013-06-10) Tujunen, Noora-Maria
Sähkötekniikan korkeakoulu | Master's thesis
Glutamaatti on yleisin hermovälittäjäaine nisäkkäiden keskushermostossa. Häiriöt sen säätelyssä on liitetty useisiin neurologisiin sairauksiin, kuten Alzheimerin tautiin, skitsofreniaan ja Parkinsonin tautiin. Näihin sairauksiin liittyvien oireiden lievittämiseen tai poistamiseen käytettävien menetelmien lisäksi tehokas hoitaminen vaatii myös glutamaatin ja muiden hermovälittäjäaineiden pitoisuuksien seuraamista aivoissa. Sähkökemiallisia menetelmiä on käytetty laajalti hermovälittäjäaineiden tunnistamisessa. Amperometriset bioanturit soveltuvat hyvin sähköisesti inaktiivisten hermovälittäjäaineiden, kuten glutamaatin ja asetyylikoliinin, havaitsemiseen. Tämä vaatii kuitenki spesifisten entsyymien immobilisointia elektrodin pinnalle. Tässä työssä tutkitti sekä itse valmistettujen että kaupallisten amperometristen bioanturien toimintaa in vitro olosuhteissa. Anturien rakenteelliseen tutkimiseen käytettiin optista mikroskopiaa ja pyyhkäisyelektronimikroskopiaa. Mittaukset suoritettiin sekoittamattomissa liuoksissa dekantterilasissa tai erikoisvalmisteisessa virtauskammiosysteemissä. Erilaisten glutamaatti- ja askorbiinihappokonsentraatioiden lisäksi myös lämpötilan vaikutus pyrittiin selvittämään. Kokeet osoittivat, että anturien vaste on korkeampi 37 °C:ssa kuin huoneenlämmössä. Lopputuloksista on lisäksi pääteltävissä, että toimintakykyisten pinnoituskerrosten kehittäminen amperometrisille bioantureille ei ole yksioikoista. Tämä johtuu haasteista valmistaa yhtenäinen pinnoite sekä pinnoitteen heikosta adheesiosta platinapintaan. Lisäksi kaupallisilla antureilla suoritettujen mittausten perusteella voidaan sanoa, että kehitystyössä kokeita suunniteltaessa on huomioitava onko käytettävä anturi optimoitu toimimaan in vivo vai in vitro-ympäristössä.
Hihnakalanterin teräshihnan kunnonvalvonta
(2008) Kontto, Antti
Faculty of Electronics, Communications and Automation | Master's thesis
Tämän diplomityön päätavoite oli selvittää tekniikoita, joilla pystyttäisiin parantamaan hihnakalanterin teräshihnan kunnonvalvontaa nykyisestään. Eri tekniikoilla pyrittiin selvittämään teräshihnan pyörimistaajuus sekä havaitsemaan teräshihnaan syntyneet viat. Työssä testattiin eri tekniikoiden soveltuvuutta ongelmien ratkaisuun. Teräshihnan pyörimistaajuuden määrittämiseen käytettiin autokorrelaatiota, pyörrevirta-anturia sekä valokennoa. Teräshihnassa olevien vikojen havaitsemiseksi testattiin pyörrevirta-anturin sekä mikrofonin soveltuvuutta. Testattavia tekniikoita valittaessa valintakriteereinä pidettiin yksinkertaisuutta, alhaisia kustannuksia sekä käyttöön soveltuvia valmiita toteutuksia. Testit suoritettiin kaikille muille paitsi autokorrelaatiolle laboratorio-olosuhteissa tarkoitukseen suunnitellulla testilaitteella. Tämän lisäksi teräshihnan pyörimistaajuuden määritystä testattiin tuotantolaiteessa autokorrelaation ja pyörrevirta-anturin osalta. Testilaitteella sekä tuotantolaitteella saatujen tuloksien yhdistämisen jälkeen voidaan todeta, että teräshihnan pyörimistaajuuden määrittämiseen soveltuvat parhaiden autokorrelaatio sekä valokenno. Pyörrevirta-anturin toiminta oli vaaditulla tasolla testilaitteella tehdyissä testeissä, mutta tippuivat käyttökelvottomiksi tuotantolaitteella. Vian havainnointiin testilaitteella soveltui paremmin pyörrevirta-anturi herkkyytensä sekä tarkkuutensa johdosta. Myös mikrofoneilla päästiin hyviin tuloksiin, mutta sen herkkyys ei yltänyt pyörrevirta-anturin tasolle.
Improvement of osseointegration: Guiding cells with external factors including a novel surface microstructure and recognizing bacterial infections
(2013) Kaivosoja, Emilia
School of Electrical Engineering | Doctoral dissertation (article-based)
The aim of this study was to find methods that could potentially improve the osseointegration of an implant. The prerequisites for implant integration into bone are the adhesion of the osteoblastic cells and the ability of the progenitor cells (stem cells) to differentiate into bone cells on the surface of the implant. It was found that patterning with diamond-like carbon, Cr, Ta or Ti improved the cytocompatibility of Si substrates with osteoblastic cells and mesenchymal stem cells (MSC). The patterns affected the density of the cells, causing local cellular spots on the patterns initiating the clustering of the cells and the cell–cell contacts, which are considered necessary for osteogenesis. Indeed, patterning improved the osteogenic differentiation of MSCs compared to planar non-patterned surfaces. With three-dimensional surfaces, the aim was to promote tissue-like growth and activationof the cytoskeleton; many previous studies have shown that this improves osteogenesis. However, this work showed that activation of the cytoskeleton alone is not osteoinductive. The osteoblastic differentiation of MSCs on 20 μm high pillars was studied, and it was found that the cytoskeleton of the cells was highly activated, but that osteogenesis was not stimulated; in fact, it was suppressed. The likely reason for this behaviour was the failure of adequate osteoinductive cell–cell contacts. In addition to growth substrate variables, the fate of the stem cells is regulated by physicalforces and soluble factors. It was found that pulsed electromagnetic fields improved the viability of the MSCs, but that they had no significant effect on their osteogenic differentiation at the relatively low seeding density used here. In contrast, a prohormone (dehydroepiandrosterone, DHEA) improved osteogenesis at least in part due to an intracrine conversion of DHEA into a sex steroid (dihydrotestosterone), but also via some other as yet undefined mechanisms. In addition to the integration of implants with tissues via contact with other cells and extracellular matrix, another important factor regulating implant integration and the lifetime of the implant is the amount of contact it has with commensials and pathogenic microbes, in particular bacteria. Diagnostics of peri-implant infections is usually based on the bacterial culture, neutrophil infiltrates and other methods. Nonetheless, the current methods are not reliable enough. In the final part of this thesis, two methods that could potentially be utilised to diagnose implant infections were evaluated. It was found that time-of-flight secondary ion mass spectrometry is a potential tool for differentiating of acellular bacterial from eukaryotic footprints (i.e. extracellular polymeric substance and extracellular matrix produced by the respective cells) and may have potential for the post-hoc diagnosis of colonisation, biofilm formation and implant-related infections even in culture negative cases.
An Investigation of Reliability of High Density Electronic Package-to-Board Interconnections from the Perspective of Solder Joint Metallurgy
(2010) Peng, Weiqun
School of Electrical Engineering | Doctoral dissertation (article-based)
The integration and miniaturization trend of the electronic packaging leads to much finer pitch of the device and package lead terminations. Several reliability concerns and issues that were previously not encountered are now surfacing. The objective of this thesis work is to investigate the reliability of the package-to-board interconnection from the perspective of solder joint metallurgy. It was carried out with several advanced packages such as CSP, WLCSP and leadless ceramic packages on organic laminate PWBs using tin-silver-copper based interconnection materials. The assemblies were subjected to several loading conditions and levels such as thermal, mechanical, and environmental stresses. As expected, the board level reliability (BLR) of electronic assemblies strongly depended on microstructure and morphology of the solder joints. Dispersion strengthening effect of the intermetallic compounds (IMCs), coarsening of the IMC particles, strain rate hardening, solder fatigue, and recrystallization of Sn grains in the highly stressed areas were observed. These were found to directly impact Pb-free solder joint reliability. Appropriate thermal aging can improve joint reliability up to 50% due to coarsening of the IMC particles. In addition, other factors such as dissolution of metals, interfacial reactions, IMC spalling, and cross interaction of surface materials on the two sides of the joints were also observed and discussed. The effects can be expressed as a series of interactive relationships: materials (pad surface materials and solder alloy composition) and/or soldering process lead to microstructure change in bulk solder and/or at interface, which in turn leads to joint reliability variation.
Kolmiakselisen kiihtyvyysanturin tuotantotestauksen optimointi
(2008) Laurén, Janne
Faculty of Electronics, Communications and Automation | Master's thesis
Digitaalisuus ja pieni koko ovat ovat tämän hetken avainsanat tekniikan alalla. Pysyäkseen mukana kovassa kilpailussa myös VTI Technologies Oy on kehittänyt uuden MEMS-tekniikalla valmistettavan digitaalisen kiihtyvyysanturin. Tämän työn tarkoituksena oli kehittää VTI:n uuden digitaalisen kiihtyvyysanturikomponentin testausta massatuotannon vaatimalle tasolle niin kustannustehokkuuden kuin laadun ja suorituskyvyn osalta. Kehitystarpeisiin sisältyi sekä testauksen nopeuttamista että sen tarkkuuden parantamista. Työn alussa esitellään testauksen kohteena oleva kiihtyvyysanturikomponentin ominaisuudet ja rakenne. Lisäksi käsitellään perusteet tuotteen valmistuksen eri vaiheista. Tämän jälkeen tutustutaan tuotantotestaukseen, sen tarkoitukseen ja vaatimuksiin. Lisäksi esitellään tuotantotestauksessa käytettävä testauslaitteisto. Loppuosassa esitetään varsinaisen työn menetelmät ja saavutukset. Parannuksissa kerrotaan millä tavoin tuotteen kalibroinnin tarkkuutta parannettiin kehittämällä kalibrointialgoritmeja. Lisäksi kerrotaan miten testauksessa suoritettavia mittauksia nopeutettiin kehittämällä testausohjelman toimintaa niin ylätasolla kuin datankäsittelyssäkin. Saavutetut tulokset olivat paremmat kuin alkuun osattiin kuvitella. Työn avulla saatiin huomattavasti sekä parannettua tarkkuutta että lyhennettyä testiaikaa, kun verrataan tuloksia alkuperäiseen testaukseen.
Lastuavien työstökeskusten elektroniikka
(2008) Ruohonen, Janne
Faculty of Electronics, Communications and Automation | Master's thesis
Työn tarkoituksena oli selvittää nykyaikaisissa työstökeskuksissa ja sorveissa käytettävää elektroniikkaa sekä niiden ohjausta ja ohjelmointia. Tarkoituksena oli myös kartoittaa kyselytutkimuksen avulla eri valmistajien koneiden välisiä eroja sekä seikkoja, jotka vaikuttavat koneiden hankintaan. Työstökeskus on laite, jonka avulla erilaisista aihioista voidaan lastuavalla työstöllä poistaa materiaalia ja tehdä näin erimuotoisia kappaleita. Työstökeskuksen tärkeimmät sähköiset osat ovat karamoottori, pöytää liikuttavat servomoottorit sekä moottoreiden ohjauselektroniikka. Lisäksi työstökeskuksissa on oltava jonkinlainen ohjauspaneeli käyttöliittymällä, jotta laitetta voidaan käyttää. Numeerisesti ohjatut työstökeskukset ja sorvit toimivat nopeasti ja tarkasti ennalta tehdyn ohjelmakoodin mukaisesti. Ohjelmakoodia voidaan kirjoittaa joko suoraan käsin tai koodia voidaan luoda tietokoneohjelmien avulla, valmiiksi piirretyistä kuvista. Eri valmistajien koneissa on hieman erilaisia ratkaisuja käyttöliittymän ja ohjelmoinnin suhteen, mutta perusajatukseltaan kaikki koneet ovat hyvinkin samanlaisia. Tutkimuksessa keskityttiin lähinnä Haas-, Fanuc- sekä Mazak-merkkisiin työstökoneohjauksiin. Fanuc valmistaa myös pelkkiä ohjauksia, Haas sekä Mazak valmistavat koneita omilla ohjauksillaan eivätkä myy muille konevalmistajille ohjauksia. Tulosten perusteella voidaan todeta, että Fanuc- ja Haas-merkkisten koneiden ohjaus on melko lähellä toisiaan. Näihin koneisiin käyvät ohjelmat sekä koneiden käyttäminen ovat tutkimuksen mukaan lähellä toisiaan. Mazak erottuu käyttöliittymällään kahdesta muusta jonkin verran.
LED lighting combined with solar panels in developing countries
(2011) Amogpai, Ater
Sähkötekniikan korkeakoulu | Doctoral dissertation (article-based)
The aim of the work was to find out the functionality of LED lighting combined with solar panels in developing countries and to find out the availability of solar energy in different geographical locations. Another aim of the work was to understand the advantages and disadvantages of photovoltaic systems and the optimum combination of PV systems for lighting. Measurements of photovoltaic systems combined with LEDs and fluorescent lighting were conducted in an office building in Finland. Measurements in a one-room house in Sudan using LEDs and fluorescent and incandescent lamps were also conducted. The costs analysis comparing photovoltaics and diesel generators in Sudan are discussed. The results showed that in Finnish conditions photovoltaic systems may be combined with AC power sources and DC rectifiers. However, in Sudanese conditions, where solar radiation is available all the year round, photovoltaic systems can be used without inverters. LED lighting combined with solar panels was found to be suitable for lighting in developing countries. Photovoltaic systems have shown high potential for electricity generation in Sudan.
LED-kasvivalaisin
(2008) Anttila, Toni
Faculty of Electronics, Communications and Automation | Master's thesis
LED-teknologian käyttö kasvihuonevalaistuksessa tulee lisääntymään. LED-valaistuksen etuja ovat mahdollisuudet energian säästöön, kasvatustilan vähentäminen ja mahdollisuudet kontrolloida kasvien kasvua. Tulevaisuudessa erityisvalaistuksen määrä kasvien kasvatuksessa tulee lisääntymään. Tässä työssä suunniteltiin ja rakennettiin LED-kasvivalaisin. Työssä käytiin läpi teoreettinen pohja kasvivalotukselle ja esiteltiin suunnittelun ja rakentamisen eri vaiheet ongelmineen ja erityispiirteineen. Lopuksi mittaustulokset. Huolimatta valittujen komponenttien heikosta laadusta valaisimet saatiin valmiiksi ja ne toimivat lähes suunnitelmien mukaisesti. Valaisimet asennetaan Teknillisen Korkeakoulun valaistusyksikön ja Helsingin yliopiston Sovelletun biologian laitoksen LEDFlowers-tutkimusprojektin käyttöön Viikin kasvihuoneelle.
Life cycle assessment of light sources – Case studies and review of the analyses
(2013) Tähkämö, Leena
School of Electrical Engineering | Doctoral dissertation (monograph)
Lighting is a major global consumer of electricity and undergoing drastic changes due to legislative and voluntary measures. Widely-used conventional light sources, such as incandescent lamps and high pressure mercury lamps, are banned from the European Union market. The number of light sources on the market is expanding especially regarding the LED lamps and luminaires. These major changes in the lighting sector create a need for evaluating the environmental performance of light sources, especially as the changes are justified by the environmental aspects, such as energy consumption. The life cycle assessment method is standardized on a general level, but no established rules exist for conducting a life cycle assessment of light sources in detail. In most cases, it is impossible to directly compare the results of different assessments. Because of the major changes in the lighting market, it is useful to assess the environmental impacts of various light sources in similar methods. The work addresses this problem by presenting two models, a simple and an extensive one, for conducting the life cycle assessment of light sources rapidly and in a transparent, comparative way. The models are developed on the basis of four case studies presented in the work and a review to the life cycle assessment found in the literature. Both models are simplified, and they recommend the key parameters of the life cycle assessment: functional unit, stages of the life cycle, environmental impacts, and energy source in use stage. Four case studies were conducted in the work: two life cycle assessments of a fluorescent lamp luminaire and an LED downlight luminaire, one life cycle cost analysis of street lighting luminaires, and one analysis combining both life cycle assessment and life cycle cost analysis of non-directional lamps. The case studies and the review of the previous life cycle assessments concluded similar findings despite the differences in the methods, scopes and evaluated light sources. The main conclusion of the life cycle assessments was the clear dominance of the use stage energy consumption. The environmental impacts of the use were found to be sensitive to the life of the light source and the used energy source. The dominance of the use stage was the clearest in light sources of low luminous efficacy and low manufacturing efforts and when using high-emission energy sources. The manufacturing was usually the second significant cause for average environmental impacts. The importance of the manufacturing is estimated to increase by a more detailed assessment of the manufacturing processes. The average environmental impacts of other life cycle stages, such as transport and end-of-life, were found practically negligible, but possibly notable in a certain environmental impact category.
Mittauselektroniikan komponenttilevyjen valmistukselle asetettavat vaatimukset
(2008) Kurki, Pekka
Faculty of Electronics, Communications and Automation | Master's thesis
Kun yritykset tilaavat komponenttilevyjen valmistusta alihankkijoilta, eräs merkittävä osa valmistussopimusta on valmistusvaatimusten asettaminen. Tässä työssä käsiteltiin kysymystä siitä, minkälaisia valmistusvaatimuksia mittauselektroniikkalaitteiden komponenttilevyjen valmistukselle kannattaa asettaa, miten vaatimusten asettaminen tulee suorittaa ja miten vaatimusten toteutumista voidaan valvoa. Asiaa tutkittiin perehtymällä komponenttilevyjen valmistuksen vaiheisiin ja niihin liittyviin standardeihin sekä menetelmiin, mihin viittaamalla vaatimuksia voidaan esittää. Vaatimusten toteutumisen valvontaa varten perehdyttiin erilaisiin tarkastus- ja testausmenetelmiin. Työn tuloksena syntyi valmistusvaatimusdokumentti, joka voidaan asettaa liitteeksi tilaussopimuksiin. Lisäksi annettiin ohjeita ja esimerkkejä, joiden perusteella komponenttilevyjen suunnittelija voi valita levylle sopivat valmistusvaatimukset. Komponenttilevyjen valmistusvaatimusten asettaminen osoittautui hyvin suoraviivaiseksi tehtäväksi. Se voidaan suorittaa standardeihin viittaamalla ja kirjaamalla ylös muita asioita joita komponenttilevyjä tilaava yritys alihankkijalta haluaa. Puhtausvaatimusten asettaminen osoittautui kuitenkin mutkikkaaksi, koska yhtä oikeaa kaikille levyille riittävää puhtauden tasoa ei ole. Vaatimuksia asetettaessa tulee myös huomioida, että eri levyille asetettavat vaatimukset poikkeavat toisistaan.
A mobile recording system and an acquisition control method for average event-related potential measurements
(2012) Paukkunen, Antti
School of Electrical Engineering | Doctoral dissertation (article-based)
Event-related potentials (ERPs) are a result of the activity elicited in the brain during the performance of a cognitive task. They can be studied by using an EEG, and are used to investigate the brain functions related to the processing of sensory data, and memory. The technique is flexible, and affordable, and has various potential diagnostic applications. The clinical feasibility, however, is limited due to the low measurement reliability. In addition, performance of the tests could be enhanced if the recording devices were more robust. The current study presents two ways of improving the performance of ERP measurements. The first deals with the improvement of the efficiency of the recording procedure and the second, with the optimization of the recording system design for clinical use. In addition, the discussion on improving the measurement reliability is contributed to by conducting a study with mismatch negativity (MMN) to determine the relationship between the measurement error and the test-retest reliability. To improve the recording procedure, an acquisition control method is suggested which helps optimize the amount of data recorded in terms of its concurrent quality. It allows optimization of the recording time and control of the measurement error, which reduces subject discomfort and improves measurement repeatability. In the MMN study conducted, the effect varied, depending on the parameterization, and whether the deviant responses were studied separately or as a profile. It was, however, generally significant, and repeatability was estimated to keep improving until the error level went below 10% of the peak amplitude. Second, a mobile ERP recording system design with an integrated audio stimulation unit is presented. It is easy to apply, and capable of performing online data analysis. It is also tolerant of external interference because of its compact size, close proximity to the measured target, and the average grounding arrangement it uses. This kind of design allows fluent performance of the measurements in applications where the target activity is well-defined, which is important in an attempt to allow clinical use to be made of them. Together with the application of the algorithm developed, it provides easy access to ERPs and makes the investigations efficient, and less inconvenient.
Numerical simulations for reliability assessment of lead-free solder interconnections in BGA packages
(2011) Li, Jue
Sähkötekniikan korkeakoulu | Doctoral dissertation (article-based)
This work presents the results of computer-aided numerical simulations for the reliability assessment of lead-free solder interconnections in BGA packages. The finite element and Monte Carlo methods were employed for the macroscale structural and the mesoscale microstructural simulations, respectively. The major reliability tests for electronic component boards, i.e. thermal cycling, power cycling and drop impact tests, were simulated via the finite element method. The results provide a feasible tool for a better understanding of the observed failure modes in the reliability tests. The lifetime predictions based on the simulation results are helpful for the lifetime estimations of the BGA packages. The temperature effects on the drop impact reliability of the BGA packages were successfully elucidated by the finite element numerical experiments. In addition, a new algorithm was developed in order to predict dynamic recrystallization in solder interconnections during thermal cycling. The approach was realized by combining the Potts model based Monte Carlo method and the finite element method. The correlation between real time and Monte Carlo simulation time was established with the help of the in situ test results. Recrystallization with the presence of intermetallic particles in the solder matrix was simulated by introducing the energy amplification factors in the particle-affected deformation regions. The present algorithm predicted both the incubation period of the recrystallization as well as the growth tendency of the recrystallized regions in a way consistent with the experimental findings.
Ohjelmakirjaston hyödyntäminen automaatiojärjestelmässä
(2008) Kääriäinen, Jarkko
Faculty of Electronics, Communications and Automation | Master's thesis
Tässä diplomityössä työssä tarkastellaan automaatiosovelluksen rakennetta ja elinkaarta ja tutustutaan logiikkaohjelmointiin liittyvään standardiin IEC 61131. Lisäksi tutustutaan sovelluksen laatuun vaikuttaviin seikkoihin. Työssä tutkitaan, kuinka ohjelmointia voidaan tehostaa kirjastoja käyttämällä ja mitä vaatimuksia se asettaa ohjelmoinnille. Työssä kartoitetaan kahden PLC-kehitysympäristön, Step 7:n ja Unity Pro:n, ominaisuuksia ja luodaan näihin ympäristöihin yhtenäiset ohjelmakirjastot sekä nimeämiskäytäntö ohjelmoinnissa käytettäville symboleille.
Perceptions of lighting, perceived restorativeness, preference and fear in outdoor spaces
(2013) Nikunen, Heli
School of Electrical Engineering | Doctoral dissertation (article-based)
This thesis considers outdoor lighting as a fundamental factor affecting environmental experiences after dark. It explores the restorative potential of outdoor lighting within the framework provided by attention restoration theory (ART). Also, perceived safety and preference variables are included in the research work. These factors may have a major effect on outdoor space use after dark and on the level of satisfaction with the neighbourhood in which a person lives. The modern way of living calls for a capacity for long and intense periods of concentration, the ability to direct attention. However, this mental effort is susceptible to fatigue and a restorative period is needed before a person can be effective again. Thus, the need for restoration may be considerable during the evening, and public lighting environments should promote opportunities for restoration. This thesis explores how the perception of different lighting attributes is connected with the perception of restorative potential. The research method was based on subjective assessments of simulated environments as well as field assessments. The results were obtained by applying quantitative analysis methods to the assessment data. In studies III and IV, the quantitative data was supplemented with qualitative data obtained from free responses. Both hypothesis testing with ANOVA and linear regression were used for quantitative data analysis. The main finding is that the perceived quality of the lighting environment correlates with perceptions about the potential for restoration, thus providing a new framework for lighting research. The results indicate that perceived restorativeness is positively connected with the perception of such lighting attributes as the focus of light on natural scene contents and the perception of a pleasant colour quality, whereas the connection may be negative when the light is focused on urban scene contents. The results also indicate that perceptions of safe and a pleasant lighting environment are connected with the perception of a pleasant colour quality. Also, changes in the focus of the lighting affected preferences and feelings of safety, so that when the light was focused on natural scene contents, the preferences and perceptions of safety were higher, whereas they were lower when the light was focused on parking lots and roads. Thus, the results suggest putting more weight on the quality of lighting.
Phonocardiography: Development of a clinical system and its application to screening for paediatric heart murmurs
(2012) Lukkarinen, Sakari
School of Electrical Engineering | Doctoral dissertation (article-based)
Screening for heart murmurs in children is an area of healthcare in which significant gains can be made in terms of efficiency. Due to diagnostic uncertainties in primary healthcare, heart murmurs, most of which are innocent, are the most common reason for referrals to a paediatric cardiologist. The phonocardiographic system, updated with current technology, could provide the additional information necessary to screen for heart murmurs in children reliably. In this thesis a prototype of a phonocardiographic system for non-cardiologist use was developed and its applicability to screening for heart murmurs in children was evaluated. A special feature of the system was the combined phonospectrographic view that could be used to analyse the features of the heart sounds and murmurs. The system was used to collect two independent heart sound databases in cooperation with Helsinki University Hospital and Lund University Hospital. Experienced paediatric cardiologists examined the children and analysed their heart sounds. The timing, duration, and frequency contents of heart sounds and murmurs were extracted from the sound signals. Statistical analysis was used to find the most significant features for screening between pathological and physiological cases. The system was capable of recording, displaying and replaying common heart murmurs in children. The characteristics of the heart murmurs in children were illustrated in phonospectrograms. The timing and quality of the cardiovascular sound events were measured from the graphical presentations. With the use of time interval and spectral analysis as well as a stepwise regression analysis model, all significant cardiac defects were correctly classified as pathological. In phonospectrographic analysis of heart murmurs in children, a sensitivity of 90% and specificity of 92% in screening for pathological heart murmurs were achieved. The digital phonocardiographic system for screening for heart murmurs in children can be implemented rather simply using an electronic stethoscope and a personal computer. The enhanced phonospectrographic presentation of the heart sounds and murmurs provides more information than traditional auscultation or phonocardiography alone. Simple features extracted from the phonospectrogram may significantly improve the diagnostic quality of primary healthcare in screening for heart murmurs in children and thus lead to more efficient use of personnel and technical resources in the whole healthcare system.
Raajanpidennyshoidon kokonaiskustannusten arviointi
(2013-08-26) Gröhn, Erika
Sähkötekniikan korkeakoulu | Master's thesis
Alaraajojen pituuseron vaikutukset alaraajojen, lantion ja selkärangan fysiologiaan sekä yleisesti elämänlaatuun ovat pitkään olleet lisääntyvän mielenkiinnon kohteena. Pituuseroja voidaan hoitaa raajan pidennysleikkauksella, jossa lyhyemmän jalan reisi- tai sääriluuhun tehdään keinotekoinen murtuma ja luun päitä vedetään hitaasti ja hallitusti erilleen tarkoitukseen suunnitellulla pidennyslaitteella. Näiden pidennyslaitteiden päätyyppejä ovat kehon ulkoiset hoitolaitteet sekä täysin implantoitavat, luuydinnaulaukseen perustuvat laitteet. Kehon ulkoisiin hoitolaitteisiin liittyvät komplikaatiot ovat heikentäneet laitteen houkuttelevuutta sen edullisesta hankintahinnasta huolimatta. Luuydinnauloilla puolestaan kallis hankintahinta on hidastanut laitteiden yleistymistä, vaikka komplikaatiotaajuuden on todettu olevan alhaisempi. Laitteen hankintakustannus on kuitenkin vain osa raajanpidennyshoidon kokonaiskustannuksia, joita alhaisempi komplikaatiotaajuus voisi merkittävästi pienentää. Tämän diplomityön tavoitteena on selvittää, ovatko raajanpidennyshoidon täysin implantoitavia laitteita käyttävät hoitomenetelmät kokonaiskustannuksiltaan edullisempia kuin ulkoisia hoitolaitteita käyttävät menetelmät. Kokonaiskustannusten laskennassa otetaan huomioon hoitoprosessiin normaalisti kuuluvien kustannusten lisäksi komplikaatioista aiheutuvat kustannukset sekä potilaiden työkyvyttömyydestä aiheutuvat kustannukset. Tutkimushypoteesina on luuydinnaulojen alhaisempi komplikaatiotaajuus ja nopeampi kuntoutuminen, joka tuottaa alhaisemmat hoidon kokonaiskustannukset. Diplomityötä varten kerättiin 40 raajanpidennyspotilaan potilasasiakirja-aineisto, jonka perusteella muodostettiin malli kokonaiskustannusten laskemiseksi. Tutkitun potilasaineiston luuydinnaulapotilailla kokonaiskustannukset olivat pienemmät kuin ulkoisilla hoitolaitteilla hoidetuilla potilailla. Myös komplikaatiokustannusten osuus kokonaiskustannuksista oli luuydinnaulapotilailla pienempi. Jatkossa tutkimukseen tulee sisällyttää suurempi potilasaineisto, jotta tuloksista saadaan luotettavampia. Tässä työssä muodostettua kustannusmallia voidaan soveltaa myös suurempaan potilasaineistoon.