Bayesian Estimation of Noise

In mathematical modeling the estimation of the model parameters is one of the most common problems. The goal is to seek parameters that fit to the measurements as well as possible. There is always error in the measurements which implies uncertainty to the model estimates. In Bayesian statistics all the unknown quantities are presented as probability distributions. If there is knowledge about parameters beforehand, it can be formulated as a prior distribution. The Bays’ rule combines the prior and the measurements to posterior distribution. Mathematical models are typically nonlinear, to produce statistics for them requires efficient sampling algorithms. In this thesis both Metropolis-Hastings (MH), Adaptive Metropolis (AM) algorithms and Gibbs sampling are introduced. In the thesis different ways to present prior distributions are introduced. The main issue is in the measurement error estimation and how to obtain prior knowledge for variance or covariance. Variance and covariance sampling is combined with the algorithms above. The examples of the hyperprior models are applied to estimation of model parameters and error in an outlier case.

Modeling and Analysis of Noise and Interconnects for On-Chip Communication Link Design

This thesis considers modeling and analysis of noise and interconnects in onchip communication. Besides transistor count and speed, the capabilities of a modern design are often limited by on-chip communication links. These links typically consist of multiple interconnects that run parallel to each other for long distances between functional or memory blocks. Due to the scaling of technology, the interconnects have considerable electrical parasitics that affect their performance, power dissipation and signal integrity. Furthermore, because of electromagnetic coupling, the interconnects in the link need to be considered as an interacting group instead of as isolated signal paths. There is a need for accurate and computationally effective models in the early stages of the chip design process to assess or optimize issues affecting these interconnects. For this purpose, a set of analytical models is developed for on-chip data links in this thesis. First, a model is proposed for modeling crosstalk and intersymbol interference. The model takes into account the effects of inductance, initial states and bit sequences. Intersymbol interference is shown to affect crosstalk voltage and propagation delay depending on bus throughput and the amount of inductance. Next, a model is proposed for the switching current of a coupled bus. The model is combined with an existing model to evaluate power supply noise. The model is then applied to reduce both functional crosstalk and power supply noise caused by a bus as a trade-off with time. The proposed reduction method is shown to be effective in reducing long-range crosstalk noise. The effects of process variation on encoded signaling are then modeled. In encoded signaling, the input signals to a bus are encoded using additional signaling circuitry. The proposed model includes variation in both the signaling circuitry and in the wires to calculate the total delay variation of a bus. The model is applied to study level-encoded dual-rail and 1-of-4 signaling. In addition to regular voltage-mode and encoded voltage-mode signaling, current-mode signaling is a promising technique for global communication. A model for energy dissipation in RLC current-mode signaling is proposed in the thesis. The energy is derived separately for the driver, wire and receiver termination.

”AMERICAN ENVIRONMENTS”. Ympäristön merkitykset Don DeLillon romaanissa White Noise

Pro gradu -tutkielmani tavoitteena on analysoida ympäristön merkityksiä yhdysvaltalaiskirjailija Don DeLillon (1936-) romaanissa White Noise (1985). Lähestyn romaania ekokriittisen kirjallisuudentutkimuksen näkökulmasta ja kytken sen ekokriitikko Lawrence Buellin ajatukseen nk. ympäristöalitajunnasta. Analysoin DeLillon romaania myös yhteydessä filosofi Jean Baudrillardin ajatukseen postmodernin ajan länsimaisessa ja erityisesti amerikkalaisessa yhteiskunnassa vallalla olevasta simulaatioiden järjestelmästä. White Noise -romaanin todellisuus vastaa Baudrillardin ajatusta yhteiskunnasta, jossa representaatiot ja simulaatiot ovat korvanneet todellisuuden. Media, erityisesti televisio, tuottaa jatkuvasti kuvia ja simulaatioita, joiden kyllästämässä todellisuudessa aineellinen maailma ja luonto jäävät tavoittamattomiin. White Noise -romaanin henkilöiden yhteys aineelliseen ympäristöönsä ja luonnonilmiöihin on katkennut, sillä heidän arkensa pyörii pitkälti kuluttamisen ja televisionkatselun ympärillä. Romaanin todellisuudessa myös identiteetistä on tullut eräänlainen tuote, jonka jokainen voi rakentaa mieleisekseen kulutusvalinnoillaan. Identiteettiproblematiikan ohella myös kuolemalla on keskeinen asema tutkielmassani. White Noise -romaanin päähenkilö Jack Gladney kärsii paniikinomaisesta kuolemanpelosta, jota pyrkii torjumaan erilaisin keinoin siinä kuitenkaan onnistumatta. Tavoitteenani on osoittaa, että tämä piinaava pelko kuolemaa kohtaan on syntynyt simulaatioyhteiskunnan tuloksena. Vieraantuminen aineellisesta maailmasta ja luonnon prosesseista on johtanut vieraantumiseen ruumiista ja kuolemasta. Analysoin kuolemaa romaanissa eräänlaisena simulaatioiden maailman äärirajana, viimeisenä luonnollisena tapahtumana. White Noise -romaanin päähenkilö Jack Gladney ahdistuu kulutuskeskeisessä, simulaatioiden kyllästämässä elinympäristössään. Tulkitsen tämän ahdistuksen tarpeena tunnistaa tärkeä vuorovaikutussuhde yksilön ja hänen aineellisen ympäristönsä välillä. Jack ei ole vielä täysin sulautunut osaksi simulaatioiden maailmaa, vaan hän tiedostaa kytköksen itsensä ja aineellisen maailman välillä. Tämä romaanista implisiittisesti esiin nouseva tiedostamisen tunne korostaa ihmisen ja ympäristön sekä laajemmin kulttuurin ja luonnon välttämätöntä yhteyttä. DeLillon romaanista on löydettävissä ajatus ympäristöalitajunnasta, joka alleviivaa ympäristön ja luonnon merkitystä ihmiselle.

Gelatin as an additive in bio-based barrier films

The main objective of the present study was to verify the approach on starch-gelatin blending for the paperboard coating formulations with enhanced barrier and mechanical properties. Based on that, another objective was to find out, how the approach will function with wood-based polysaccharides (CMC, EHEC and HPC) by analyzing their barrier properties and convertibility. The last objective was to find out, if pigments can be used in the composition of polysaccharide-protein blends without causing any negative effect on stated properties. The whole process chain of the barrier coating development was studied in the research. The methodology applied included pilot-scale coating and converting trials for the evaluation of mechanical properties of obtained coatings, namely their exposure to cracking with the loss of barrier properties. The results obtained indicated that the combination of starch with gelatin, in fact, improves the grease barrier properties and flexibility of starch-based coatings, thereby confirming the offered approach. The similar results were obtained for CMC, exhibited elevated barrier properties and surface coverage, proving that the approach also functions with wood-based polysaccharides. The introduction of equal amounts of talc gave various effects at different gelatin dosages on barrier properties of wood-based polysaccharides. Mainly, the elevation of grease barrier properties was observed. The convertibility of talc-filled coatings was not sufficient.

Characterization Of Process Efficiency Improvement In Laser Additive Manufacturing

Laser additive manufacturing (LAM), known also as 3D printing, has gained a lot of interest in past recent years within various industries, such as medical and aerospace industries. LAM enables fabrication of complex 3D geometries by melting metal powder layer by layer with laser beam. Research in laser additive manufacturing has been focused in development of new materials and new applications in past 10 years. Since this technology is on cutting edge, efficiency of manufacturing process is in center role of research of this industry. Aim of this thesis is to characterize methods for process efficiency improvements in laser additive manufacturing. The aim is also to clarify the effect of process parameters to the stability of the process and in microstructure of manufactured pieces. Experimental tests of this thesis were made with various process parameters and their effect on build pieces has been studied, when additive manufacturing was performed with a modified research machine representing EOSINT M-series and with EOS EOSINT M280. Material used was stainless steel 17-4 PH. Also, some of the methods for process efficiency improvements were tested. Literature review of this thesis presents basics of laser additive manufacturing, methods for improve the process efficiency and laser beam – material- interaction. It was observed that there are only few public studies about process efficiency of laser additive manufacturing of stainless steel. According to literature, it is possible to improve process efficiency with higher power lasers and thicker layer thicknesses. The process efficiency improvement is possible if the effect of process parameter changes in manufactured pieces is known. According to experiments carried out in this thesis, it was concluded that process parameters have major role in single track formation in laser additive manufacturing. Rough estimation equations were created to describe the effect of input parameters to output parameters. The experimental results showed that the WDA (width-depth-area of cross-sections of single track) is correlating exponentially with energy density input. The energy density input is combination of the input parameters of laser power, laser beam spot diameter and scan speed. The use of skin-core technique enables improvement of process efficiency as the core of the part is manufactured with higher laser power and thicker layer thickness and the skin with lower laser power and thinner layer thickness in order to maintain high resolution. In this technique the interface between skin and core must have overlapping in order to achieve full dense parts. It was also noticed in this thesis that keyhole can be formed in LAM process. It was noticed that the threshold intensity value of 106 W/cm2 was exceeded during the tests. This means that in these tests the keyhole formation was possible.

Exit times for some processes with normally distributed noise

Denna avhandling handlar om metoder för att hitta begränsningar för det asymptotiska beteendet hos en förväntad uthoppstid från ett område omkring en xpunkt för processer som har normalfördelad störning. I huvudsak behandlas olika typer av autoregressiva processer. Fyra olika metoder används. En metod som använder principen för stora avvikelser samt en metod som jämför uthoppstiden med en återkomsttid ger övre begränsningar för den förväntade uthoppstiden. En martingalmetod och en metod för normalfördelade stokastiska variabler ger undre begränsningar. Metoderna har alla både förtjänster och nackdelar. Genom att kombinera de olika metoderna får man de bästa resultaten. Vi får fram gränsvärdet för det asymptotiska beteendet hos en uthoppstid för den multivariata autoregressiva processen, samt motsvarande gränsvärde för den univariata autoregressiva processen av ordning n.

Fabrication additive ou Impression 3D. Aperçus sur une variation terminographique

Materiaalia lisäävä valmistus eli 3D-tulostus on valmistusmenetelmä, jossa kappale tehdään 3D-mallin pohjalta materiaalikerroksia lisäämällä, käyttäen useita tekniikoita ja materiaaleja. Menetelmää sovelletaan useilla teollisuuden aloilla. Lisääviä valmistustekniikoita on kehitetty 1990-luvun alkupuolelta lähtien, ja ne monipuolistuvat jatkuvasti. Tässä pro gradu -tutkielmassa tutkitaan sovellusalan terminologian kehitystä vertailevilla menetelmillä ja luodaan kolmikielinen sanasto alan asiantuntijoille, joita edustaa Suomessa FIRPA ry. Sanaston kielet ovat englanti, ranska ja suomi. Terminologian tutkimus on perinteisesti keskittynyt sanastotyöhön ja käsiteanalyysiin, sen sijaan termihistorian tutkimus on ollut vähäisempää. Tässä työssä on tehty vertailevaa termitutkimusta sekä sanastotyön että termihistorian näkökulmista. Vertailutasoja ovat termien merkityksen muuttuminen, vertailu pivot-kielen suhteen ja kielikohtaisten ominaisuuksien tarkastelu termien muotoutumisessa. Tutkittavia asioita ovat sanastokäsitteiden väliset suhteet, synonyymien, varianttien ja uudissanojen moninaisuus, ja termien yleiskielistyminen. Samalla pohditaan muita termien muuttumiseen vaikuttavia syita. Tärkeimpänä lähteenä käytetään Wohlersin vuosiraportteja, jotka kuvaavat kattavasti koko teollisuudenalaa. Koska englannin pivot-vaikutus on voimakasta teknisillä aloilla, omankielisen terminologian kehittyminen vaatii tietoista terminologiatyötä ja aktiivista omankielisten termien käyttöä. Terminologian vakiintumista voidaan arvioida termivarianttien ja uudissanojen määristä, sekä termien yleiskielistymisestä. Terminologia muuttuu jatkuvasti toimialan kehittyessä ja vaatii säännöllistä päivittämistä. Termihistorian tunteminen tukee sanastotyön termivalintoja. Alan asiantuntijat ovat vastuussa omasta terminologiastaan, ja heidän aktiivisuutensa on tärkeää sen kehittämisessä. Toteutettu sanasto on tämän pro gradu -tutkielman liitteenä ja se julkaistaan myös FIRPA ry:n Internet-sivustolla. Suomenkielinen osio sanastosta on ensimmäinen laaja suomeksi julkaistu materiaalia lisäävän valmistuksen sanasto.

Energy and raw material consumption analysis of powder bed fusion: case study: CNC machining and laser additive manufacturing

Laser additive manufacturing (LAM), known also as 3D printing, is a powder bed fusion (PBF) type of additive manufacturing (AM) technology used to manufacture metal parts layer by layer by assist of laser beam. The development of the technology from building just prototype parts to functional parts is due to design flexibility. And also possibility to manufacture tailored and optimised components in terms of performance and strength to weight ratio of final parts. The study of energy and raw material consumption in LAM is essential as it might facilitate the adoption and usage of the technique in manufacturing industries. The objective this thesis was find the impact of LAM on environmental and economic aspects and to conduct life cycle inventory of CNC machining and LAM in terms of energy and raw material consumption at production phases. Literature overview in this thesis include sustainability issues in manufacturing industries with focus on environmental and economic aspects. Also life cycle assessment and its applicability in manufacturing industry were studied. UPLCI-CO2PE! Initiative was identified as mostly applied exiting methodology to conduct LCI analysis in discrete manufacturing process like LAM. Many of the reviewed literature had focused to PBF of polymeric material and only few had considered metallic materials. The studies that had included metallic materials had only measured input and output energy or materials of the process and compared to different AM systems without comparing to any competitive process. Neither did any include effect of process variation when building metallic parts with LAM. Experimental testing were carried out to make dissimilar samples with CNC machining and LAM in this thesis. Test samples were designed to include part complexity and weight reductions. PUMA 2500Y lathe machine was used in the CNC machining whereas a modified research machine representing EOSINT M-series was used for the LAM. The raw material used for making the test pieces were stainless steel 316L bar (CNC machined parts) and stainless steel 316L powder (LAM built parts). An analysis of power, time, and the energy consumed in each of the manufacturing processes on production phase showed that LAM utilises more energy than CNC machining. The high energy consumption was as result of duration of production. Energy consumption profiles in CNC machining showed fluctuations with high and low power ranges. LAM energy usage within specific mode (standby, heating, process, sawing) remained relatively constant through the production. CNC machining was limited in terms of manufacturing freedom as it was not possible to manufacture all the designed sample by machining. And the one which was possible was aided with large amount of material removed as waste. Planning phase in LAM was shorter than in CNC machining as the latter required many preparation steps. Specific energy consumption (SEC) were estimated in LAM based on the practical results and assumed platform utilisation. The estimated platform utilisation showed SEC could reduce when more parts were placed in one build than it was in with the empirical results in this thesis (six parts).

Metal additive manufacturing of internal flow channels with powder bed fusion processes

This thesis studies the advantages, disadvantages and possibilities of additive manufacturing in making components with internal flow channels. These include hydraulic components, components with cooling channels and heat exchangers. Processes studied in this work are selective laser sintering and selective laser melting of metallic materials. The basic principles of processes and parameters involved in the process are presented and different possibilities of internal channel manufacturing and flow improvement are introduced

Characterization of design of a product for additive manufacturing

The purpose of conducting this thesis is to gather around information about additive manufacturing and to design a product to be additively manufactured. The specific manufacturing method dealt with in this thesis, is powder bed fusion of metals. Therefore when mentioning additive manufacturing in this thesis, it is referred to powder bed fusion of metals. The literature review focuses on the principle of powder bed fusion, the general process chain in additive manufacturing, design rules for additive manufacturing. Examples of success stories in additive manufacturing and reasons for selecting parts to be manufactured with additive manufacturing are also explained in literature review. This knowledge is demanded to understand the experimental part of the thesis. The experimental part of the thesis is divided into two parts. Part A concentrates on finding proper geometry for building self-supporting pipes and proper parameters for support structures of them. Part B of the experimental part concentrates on a case study of designing a product for additive manufacturing. As a result of experimental part A, the design process of self-supporting pipes, results of visual analysis and results of 3D scanning are presented. As a result of experimental part B the design process of the product is presented and compared to the original model.

Monitoring Directed Energy Deposition Processes in Additive Manufacturing

The purpose of this study is to find out how laser based Directed Energy Deposition processes can benefit from different types of monitoring. DED is a type of additive manufacturing process, where parts are manufactured in layers by using metallic powder or metallic wire. DED processes can be used to manufacture parts that are not possible to manufacture with conventional manufacturing processes, when adding new geometries to existing parts or when wanting to minimize the scrap material that would result from machining the part. The aim of this study is to find out why laser based DED-processes are monitored, how they are monitored and what devices are used for monitoring. This study has been done in the form of a literature review. During the manufacturing process, the DED-process is highly sensitive to different disturbances such as fluctuations in laser absorption, powder feed rate, temperature, humidity or the reflectivity of the melt pool. These fluctuations can cause fluctuations in the size of the melt pool or its temperature. The variations in the size of the melt pool have an effect on the thickness of individual layers, which have a direct impact on the final surface quality and dimensional accuracy of the parts. By collecting data from these fluctuations and adjusting the laser power in real-time, the size of the melt pool and its temperature can be kept within a specified range that leads to significant improvements in the manufacturing quality. The main areas of monitoring can be divided into the monitoring of the powder feed rate, the temperature of the melt pool, the height of the melt pool and the geometry of the melt pool. Monitoring the powder feed rate is important when depositing different material compositions. Monitoring the temperature of the melt pool can give information about the microstructure and mechanical properties of the part. Monitoring the height and the geometry of the melt pool is an important factor in achieving the desired dimensional accuracy of the part. By combining multiple different monitoring devices, the amount of fluctuations that can be controlled will be increased. In addition, by combining additive manufacturing with machining, the benefits of both processes could be utilized.