Structural and operational optimisation : applications in energy systems

In this work mathematical programming models for structural and operational optimisation of energy systems are developed and applied to a selection of energy technology problems. The studied cases are taken from industrial processes and from large regional energy distribution systems. The models are based on Mixed Integer Linear Programming (MILP), Mixed Integer Non-Linear Programming (MINLP) and on a hybrid approach of a combination of Non-Linear Programming (NLP) and Genetic Algorithms (GA). The optimisation of the structure and operation of energy systems in urban regions is treated in the work. Firstly, distributed energy systems (DES) with different energy conversion units and annual variations of consumer heating and electricity demands are considered. Secondly, district cooling systems (DCS) with cooling demands for a large number of consumers are studied, with respect to a long term planning perspective regarding to given predictions of the consumer cooling demand development in a region. The work comprises also the development of applications for heat recovery systems (HRS), where paper machine dryer section HRS is taken as an illustrative example. The heat sources in these systems are moist air streams. Models are developed for different types of equipment price functions. The approach is based on partitioning of the overall temperature range of the system into a number of temperature intervals in order to take into account the strong nonlinearities due to condensation in the heat recovery exchangers. The influence of parameter variations on the solutions of heat recovery systems is analysed firstly by varying cost factors and secondly by varying process parameters. Point-optimal solutions by a fixed parameter approach are compared to robust solutions with given parameter variation ranges. In the work enhanced utilisation of excess heat in heat recovery systems with impingement drying, electricity generation with low grade excess heat and the use of absorption heat transformers to elevate a stream temperature above the excess heat temperature are also studied.

Lignoselluloosapohjaisten väkevähappohydrolysaattien jatkuvatoiminen kromatografinen fraktiointi

Työssä tutkittiin lignoselluloosapohjaisten väkevähappohydrolysaattien (monosakkaridit, rikki- ja etikkahppo) jatkuvatoimista kromatografista fraktiointia käyttäen Japan Organo SMB -prosessia. Adsorbenttinä toimi happomuotoinen (H+) vahva kationinvaihtohartsi. Panostoimista fraktiointia käytettiin vertailukohtana. Jatkuvatoimisen prosessin optimoinnilla saavutettiin monosakkaridien suurimmaksi tuottavuudeksi 283 mol/(m3 h) (panosprosessille 145 mol/(m3 h). JO-prosessilla saavutettiin korkeat rikki- ja etikkahapon saannot: 97,3 % ja 93,5 %. Monosakkaridisaanto jäi hieman alhaisemmaksi (61,7 %) johtuen monosakkaridi- ja rikkihappo-profiilien hankalasta erottamisesta. Ulostulo virtojen puhtaudet olivat korkeat: 89 % monosakkarideille, 89 % rikkihapolle ja 100 % etikkahapolle.

Etelä-Karjalan alueen yritysten jätevirrat ja jätteenkäsittelyn kannattavuus alueella

Diplomityön tavoitteena oli selvittää Etelä-Karjalan alueen yritysten jätevirtoja ja sekalaisen rakennusjätteen koostumusta. Jätevirtojen selvityksessä keskityttiin metsäteollisuuden, rakennusteollisuuden ja kaupan alan jätevirtoihin. Tarkoituksena oli selvittää mahdollisessa jätteenkäsittelylaitoksessa hyödynnettävien jätejakeiden määrät. Selvitettyjen tietojen perusteella arvioitiin erilaisten jätteenkäsittelyvaihtoehtojen kannattavuutta yritysnäkökul-masta Etelä-Karjalan alueella. Rakennusjätteen koostumusta tutkittiin lajittelemalla ja pun-nitsemalla sekalaisia rakennusjätekuormia jätejakeittain. Etelä-Karjalan alueen jätevirtoja selvitettiin muun muassa yrityshaastatteluin ja hyödyntämällä Lassila & Tikanoja Oyj:n tietokantaa. Sekalaisen rakennusjätteen lajittelututkimuksessa selvisi, että sekalaisissa rakennusjäte-kuormissa on lähes 50 m-% hyödynnettävissä olevia jätejakeita. Energiajaetta kuormissa oli yhteensä noin 34 m-% ja kaatopaikkajätettä noin 52 m-%. Kaupan alalta syntyy pää-sääntöisesti paljon pakkausmateriaaleista koostuvaa energiajaetta, kun taas metsäteollisuu-desta syntyy paljon erilaisia prosessijätteitä, joita ei voida hyödyntää työssä tutkituilla me-netelmillä. Lappeenrannan ja Imatran alueilla arvioidaan syntyvän energiajaetta metsäteol-lisuudesta, kaupan alalta ja rakennusteollisuudesta yhteensä noin 4 300 t, puujätettä noin 5 000 t ja sekalaista rakennusjätettä noin 11 700 t. Metsäteollisuuden, rakennusteollisuuden ja kaupan alan jätevirrat Etelä-Karjalassa eivät ole riittävät taloudellisesti kannattavan jätteenkäsittelylaitoksen perustamiseksi. Arvioinnissa huomioitiin laitoksen investointikustannukset sekä muut aiheutuvat kustannukset. Energiajakeen siirtokuormausasema todettiin kannattavaksi tilanteessa, jossa energiajae toimitettaisiin Etelä-Karjalan sijasta Lahteen tai Kouvolaan.

Täytekappalekolonnin likaantumisen syyt ja likaantumisen vähentämisen menetelmiä

Lateksinvalmistusprosessin aikana syntyvää jätevettä käsitellään täytekappalekolonnissa siinä olevien haihtuvien orgaanisten yhdisteiden poistamiseksi. Käsittelyprosessin aikana jätevedessä oleva kiintoaine kiinnittyy täytekappaleiden pinnalle, lopulta tukkien ne. Täytekappaleiden vaihtotyö sekä likaantuneiden täytekappaleiden pesu aiheuttavat kustannuksia. Lainsäädäntö ja sopimus kunnallisen jäteveden käsittelyn kanssa vaativat, että haihtuvien yhdisteiden päästöt lasketaan tietyn tason alapuolelle. Työn ensimmäisenä tavoitteena oli tutkia lateksitehtaan jätevesivirtojen koostumusta massa- ja ainetaseiden avulla, erityisesti täytekappalekolonnia likaavan aineen osalta. Toisena tavoitteena oli löytää menetelmiä pidentää täytekappalekolonnin ajojaksoa nykyisestä. Kolmantena tavoitteena oli löytää tai kehittää esikäsittelymenetelmä likaavan aineen poistamiseksi ennen täytekappalekolonnia. Viimeisenä tavoitteena oli optimoida prosessin ajotapa, josta saavutettaisiin säästöjä vähentyneenä energiankulutuksena. Tutkimuksen perusteella täytekappalekolonni poistaa syntyvästä jätevedestä haihtuvia orgaanisia yhdisteitä 100 prosenttia sekä kemiallista hapenkulutusta 99,5 prosenttia. Täytekappalekolonnin ajojaksoa voidaan pidentää ennakoimalla kolonnin ylä- ja alapään paine-eron perusteella sen likaantumisastetta ja täytekappaleiden vaihtotarvetta. Tutkimuksen perusteella soveltuvia jäteveden esikäsittelymenetelmiä ovat dekantointi, jossa kuuden tunnin viipymällä poistetaan kiintoainetta sekä hallittu kiintoaineen saostus, jossa kymmenen minuutin viipymällä poistetaan sekä haihtuvia orgaanisia yhdisteitä, että kiintoainetta. Energiankulutusta voidaan optimoida vähentämällä höyryn virtausta täytekappalekolonniin erotustehokkuuden siitä kärsimättä.

Safety study of hydrogen peroxide direct synthesis

Kandidaatintyön johdantokappaleessa esitellään vetyperoksidi ja mihin sitä käytetään teollisuudessa. Työssä vertaillaan antrakinoniprosessia ja suoraa prosessia sekä selvitetään nykyisin enemmän vetyperoksidituotantoon käytetyn antrakinoniprosessin ongelmakohdat ja osoitetaan, miksi suora synteesi vetyperoksidin tuotannossa olisi parempi vaihtoehto. Kandidaatintyön käsittelee suurilta osin turvallisuusongelmia, joita esiintyy suoran synteesin yhteydessä. Kirjallisuudesta on etsitty ratkaisuja näihin ongelmiin, kuten membraaniprosessin käyttöä räjähdysvaaran välttämiseksi. Pienemmän reaktorin eli ns. mikroreaktorin käyttö tuo mukanaan monia etuja vetyperoksidin tuotantoon. Tällöin prosessi on turvallisempi ja sitä on helpompi hallita. Mikroreaktorissa voidaan käyttää korkeampia lämpötiloja ja paineita kuin makroreaktorilla ilman, että räjähdysvaara prosessissa kasvaisi. Mikroreaktorin sisällä olevat mikrokanavat luovat turvallisen ympäristön synteesille. Aspen plus – simulointiohjelmalla mallinnettiin ja simulointiin suoran prosessin kriittisiä virtoja mikroreaktorissa. Tarkoituksena oli löytää virrat, joissa kulkee mahdollisesti räjähtävä kaasuseos. Kaasumaiset prosessivirrat ovat kriittisimmät vetyperoksidin suorassa synteesissä, koska ne aiheuttavat todennäköisemmin räjähdyksen kuin nestemäiset prosessivirrat. Kaikkein eniten prosessiturvallisuutta uhkaavat ainevirrat ennen ja jälkeen mikroreaktoria.

Ecosystem architecture design: endogenous and exogenous structural properties

The aim of this dissertation is to bridge and synthesize the different streams of literature addressing ecosystem architecture through a multiple‐lens perspective. In addition, the structural properties of and processes to design and manage the architecture will be examined. With this approach, the oft‐neglected actor‐structure duality is addressed and both the position and structure, and action and process are under scrutiny. Further, the developed framework and empirical evidence offer valuable insights on how firms collectively create value and individually appropriate value. The dissertation is divided into two parts. The first part comprises a literature review, as well as the conclusions of the whole study, and the second part includes six research publications. The dissertation is based on three different reasoning logics: abduction, induction and deduction; related qualitative and quantitative methodologies are utilized in the empirical examination of the phenomenon in the information and communication technology industry. The results suggest firstly that there are endogenous and exogenous structural properties of the ecosystem architecture. Out of these, the former ones can be more easily influenced by a particular actor whereas the latter ones are taken more or less for granted. Secondly, the exogenous ecosystem design properties influence the value creation potential of the ecosystem whereas the endogenous ecosystem design properties influence the value appropriation potential of a particular actor in the ecosystem. Thirdly, the study suggests that there is a relationship between endogenous and exogenous structural properties in that the endogenous properties can be leveraged to create and reconfigure the exogenous properties whereas the exogenous properties prose opportunities and restrictions on the use of endogenous properties. In addition, the study suggests that there are different emergent and engineered processes to design and manage ecosystem architecture and to influence both the endogenous and exogenous structural properties of ecosystem architecture. This study makes three main contributions. First, on the conceptual level, it brings coherence and direction to the fast growing body of literature on novel inter‐organizational arrangements, such as ecosystems. It does this by bridging and synthetizing three different streams of literature, namely the boundary, design and orchestration conception. Secondly, it sets out a framework that enhances our understanding of the structural properties of ecosystem architecture; of the processes to design and manage ecosystem architecture; and of their influence on the value creation potential of the ecosystem and the value capture potential of a particular firm. Thirdly, it offers empirical evidence of the structural properties and processes.

Drop Size Measurements in a Laboratory Scale Venturi Scrubber

Venturi scrubbers are high efficiency gas cleaners in which suspended particles are removed from gas streams by droplets formed by liquid atomisation, usually in the venturi throat. The size of the droplets formed is of fundamental importance to the performance of the equipment, both in terms of pressure drop and collection efficiency. In this study, drop sizes in a cylindrical laboratory scale venturi scrubber were measured using a laser diffraction technique. Gas velocity and liquid to gas ratios varied from 50 to 90 m/s and 0.5 to 2.0 l/m3, respectively. Water was inserted as perpendicular jets at the beginning of the throat. Measurements were performed at three positions: two located along the throat, and the last one at the end of the diffuser. The data presented here are a typical example of pneumatic atomisation and can be relevant to other industrial applications such as combustion and engine technology. Finally, results are compared to available correlations and the validity of these equations is discussed.

The Influence of Network Competence on Internationalization of SMEs

This study focuses on the relationship between organizational network competence and the internationalization process of small- and medium sized enterprises (SMEs). Over recent decades, the global business environment has become increasingly conducive to internationalization of small firms. A central facilitating factor in the process has been the emergence of networked business relationships between internationalizing firms. Research on SME internationalization has found that certain types of structures and dynamics of business networks allow SMEs access to the resources they need to enter foreign markets. This consequently means that their internationalization often becomes to depend on the networks they are embedded in. However, research so far has mostly ignored the possibility that the organizational ability to develop and manage business network relationships, network competence, may be a major underlying factor in determining how well SMEs can leverage their network relationships to enter foreign markets and consequently may determine in large part how successful their internationalization process turns out to be. This study aims to respond to those gaps, by empirically examining how the development of network competence in internationalizing SMEs influences the internationalization outcomes that they can expect, and how such network competence is conceptualized and developed. Using a mixed methods approach, survey data collected from 298 Finnish SMEs across five industry sectors is first used to examine how levels of network competence are related to internationalization propensity of SMEs and their subsequent international performance, growth and profitability as internationally operating firms. In order to illustrate in more detail the ways in which network competence is conceptualized and how it develops during the internationalization process of an SME, qualitative data from internationally operating Finnish SMEs are used. Longitudinal interview data of an internationalizing Finnish SME is accompanied by data gathered through a series of semistructured interviews of Finnish and Russian managers involved in mutual business relationship dyads. Structurally, this thesis examines the research issue as an article-based dissertation, consisting of five journal and conference publications. Three of these publications are based on the quantitative data, and the remaining two apply the qualitative interview data. The results find several aspects where network competence has a positive influence on the success of internationalizing SMEs, how it develops and what it entails conceptually in this context. Quantitatively, the level of network competence is found to have a positive relationship to various internationalization outcomes, including the propensity of SMEs to enter foreign markets and on their subsequent international performance, their growth and their profitability. Additionally, the positive relationship is divided between the relationship-specific and cross-relational dimension of network competence, in that the influence of the former is relevant for the propensity to internationalize, while the latter is for the growth and profitability of the already internationalized SMEs. Qualitatively, the results suggest, firstly, that the development process of network competence does not necessarily precede the start of the internationalization process, but may occur through a gradual learning process alongside it. And secondly, the results also imply that the conceptualization of network competence by Finnish managers of internationally operating Finnish SMEs is structurally distinct from that of their culturally distinct partner managers in Russia. This study contributes to the literature on SME internationalization in several ways. Firstly, it introduces operationalized organizational competencies to the literature on internationalization of SMEs, which has so far mainly examined the influence of business networking on the internationalization process without having such an organizational viewpoint. Furthermore, this study provides a multi-level analysis of the determinants of successful SME internationalization, by examining various strategic and performance outcomes across the process. These results also contribute to the literature on organizational strategy of internationalizing SMEs, by clarifying how different dimensions of business networking may be optimal in different phases of the internationalization process. Conceptually, the results of this study contribute to the literature on competence development and SME internationalization, by illustrating how the development process of network competence may occur during internationalization process. Thus, they also contribute to the discussion on how SMEs are able to influence the dynamics and structures of their business networks over time. Finally, this study contributes to the literature on the role of culture in the internationalization process, by implying that the cultural background of the manager of the SME may determine whether business networking and network competence is seen as an organizational-level or an individual level capability. The study also includes some additional contributions to the literature on dynamic capabilities in strategic management, and on that of strategic business networks. These include further clarifying the exact nature and tangibility of dynamic capabilities, and being one of the first studies to introduce constructs from both dynamic capabilities and business network literature to the field of international entrepreneurship. And finally, the study also has some contribution on the two streams of literature, in illustrating how both dyadic and network-level capabilities may be relevant, depending on the current strategic goals and market position of the firm. Keywords: network competence, internationalizatio

Hydrometallurgical recovery of valuable metals from secondary raw materials

Wastes and side streams in the mining industry and different anthropogenic wastes often contain valuable metals in such concentrations their recovery may be economically viable. These raw materials are collectively called secondary raw materials. The recovery of metals from these materials is also environmentally favorable, since many of the metals, for example heavy metals, are hazardous to the environment. This has been noticed in legislative bodies, and strict regulations for handling both mining and anthropogenic wastes have been developed, mainly in the last decade. In the mining and metallurgy industry, important secondary raw materials include, for example, steelmaking dusts (recoverable metals e.g. Zn and Mo), zinc plant residues (Ag, Au, Ga, Ge, In) and waste slurry from Bayer process alumina production (Ga, REE, Ti, V). From anthropogenic wastes, waste electrical and electronic equipment (WEEE), among them LCD screens and fluorescent lamps, are clearly the most important from a metals recovery point of view. Metals that are commonly recovered from WEEE include, for example, Ag, Au, Cu, Pd and Pt. In LCD screens indium, and in fluorescent lamps, REEs, are possible target metals. Hydrometallurgical processing routes are highly suitable for the treatment of complex and/or low grade raw materials, as secondary raw materials often are. These solid or liquid raw materials often contain large amounts of base metals, for example. Thus, in order to recover valuable metals, with small concentrations, highly selective separation methods, such as hydrometallurgical routes, are needed. In addition, hydrometallurgical processes are also seen as more environmental friendly, and they have lower energy consumption, when compared to pyrometallurgical processes. In this thesis, solvent extraction and ion exchange are the most important hydrometallurgical separation methods studied. Solvent extraction is a mainstream unit operation in the metallurgical industry for all kinds of metals, but for ion exchange, practical applications are not as widespread. However, ion exchange is known to be particularly suitable for dilute feed solutions and complex separation tasks, which makes it a viable option, especially for processing secondary raw materials. Recovering valuable metals was studied with five different raw materials, which included liquid and solid side streams from metallurgical industries and WEEE. Recovery of high purity (99.7%) In, from LCD screens, was achieved by leaching with H2SO4, extracting In and Sn to D2EHPA, and selectively stripping In to HCl. In was also concentrated in the solvent extraction stage from 44 mg/L to 6.5 g/L. Ge was recovered as a side product from two different base metal process liquors with Nmethylglucamine functional chelating ion exchange resin (IRA-743). Based on equilibrium and dynamic modeling, a mechanism for this moderately complex adsorption process was suggested. Eu and Y were leached with high yields (91 and 83%) by 2 M H2SO4 from a fluorescent lamp precipitate of waste treatment plant. The waste also contained significant amounts of other REEs such as Gd and Tb, but these were not leached with common mineral acids in ambient conditions. Zn was selectively leached over Fe from steelmaking dusts with a controlled acidic leaching method, in which the pH did not go below, but was held close as possible to, 3. Mo was also present in the other studied dust, and was leached with pure water more effectively than with the acidic methods. Good yield and selectivity in the solvent extraction of Zn was achieved by D2EHPA. However, Fe needs to be eliminated in advance, either by the controlled leaching method or, for example, by precipitation. 100% Pure Mo/Cr product was achieved with quaternary ammonium salt (Aliquat 336) directly from the water leachate, without pH adjustment (pH 13.7). A Mo/Cr mixture was also obtained from H2SO4 leachates with hydroxyoxime LIX 84-I and trioctylamine (TOA), but the purities were 70% at most. However with Aliquat 336, again an over 99% pure mixture was obtained. High selectivity for Mo over Cr was not achieved with any of the studied reagents. Ag-NaCl solution was purified from divalent impurity metals by aminomethylphosphonium functional Lewatit TP-260 ion exchange resin. A novel preconditioning method, named controlled partial neutralization, with conjugate bases of weak organic acids, was used to control the pH in the column to avoid capacity losses or precipitations. Counter-current SMB was shown to be a better process configuration than either batch column operation or the cross-current operation conventionally used in the metallurgical industry. The raw materials used in this thesis were also evaluated from an economic point of view, and the precipitate from a waste fluorescent lamp treatment process was clearly shown to be the most promising.

Building organizational creativity – a multitheory and multilevel approach for understanding and stimulating organizational creativity

Organizational creativity is increasingly important for organizations aiming to survive and thrive in complex and unexpectedly changing environments. It is precondition of innovation and a driver of an organization’s performance success. Whereas innovation research increasingly promotes high-involvement and participatory innovation, the models of organizational creativity are still mainly based on an individual-creativity view. Likewise, the definitions of organizational creativity and innovation are somewhat equal, and they are used as interchangeable constructs, while on the other hand they are seen as different constructs. Creativity is seen as generation of novel and useful ideas, whereas innovation is seen as the implementation of these ideas. The research streams of innovation and organizational creativity seem to be advancing somewhat separately, although together they could provide many synergy advantages. Thereby, this study addresses three main research gaps. First, as the knowledge and knowing is being increasingly expertized and distributed in organizations, the conceptualization of organizational creativity needs to face that perspective, rather than relying on the individual-creativity view. Thus, the conceptualization of organizational creativity needs clarification, especially as an organizational-level phenomenon (i.e., creativity by an organization). Second, approaches to consciously build organizational creativity to increase the capacity of an organization to demonstrate novelty in its knowledgeable actions are rare. The current creativity techniques are mainly based on individual-creativity views, and they mainly focus on the occasional problem-solving cases among a limited number of individuals, whereas, the development of collective creativity and creativity by the organization lacks approaches. Third, in terms of organizational creativity as a collective phenomenon, the engagement, contributions, and participation of organizational members into activities of common meaning creation are more important than the individualcreativity skills. Therefore, the development approaches to foster creativity as social, emerging, embodied, and collective creativity are needed to complement the current creativity techniques. To address these gaps, the study takes a multiparadigm perspective to face the following three objectives. The first objective of this study is to clarify and extend the conceptualization of organizational creativity. The second is to study the development of organizational creativity. The third is to explore how an improvisational theater based approach fosters organizational creativity. The study consists of two parts comprising the introductory part (part I) and six publications (part II). Each publication addresses the research questions of the thesis through detailed subquestions. The study makes three main contributions to the research of organizational creativity. First, it contributes toward the conceptualization of organizational creativity by extending the current view of organizational creativity. This study views organizational creativity as a multilevel construct constituting both of individual and collective (group and organizational) creativity. In contrast to current views of organizational creativity, this study bases on organizational (collective) knowledge that is based on and demonstrated through the knowledgeable actions of an organization as a whole. The study defines organizational creativity as an overall ability of an organization to demonstrate novelty in its knowledgeable actions (through what it does and how it does what it does).Second, this study contributes toward the development of organizational creativity as multi-level phenomena, introducing developmental approaches that face two or more of these levels simultaneously. More specifically, the study presents the cross-level approaches to building organizational creativity, by using an approach based in improvisational theater and considering assessment of organizational renewal capability. Third, the study contributes on development of organizational creativity using an improvisational theater based approach as twofold meaning. First, it fosters individual and collective creativity simultaneously and builds space for creativity to occur. Second, it models collective and distributed creativity processes, thereby, contributing to the conceptualization of organizational creativity.

Kuljetusvirtojen yhdistely kannattavaksi kuljetussuoritteeksi maatalouteen liittyvissä tuoteryhmissä

Diplomityön tavoitteena on arvioida kuljetusvirtojen yhdistämisen kannattavuutta. Kannattavuuden arvioimiseksi määritetään kuljetusvirtojen yhdistämisestä syntyneiden kuljetusreittien hinnat, jotka perustuvat reitillä käytettävien ajoneuvojen kuljetuskustannuksiin. Työssä kuvataan reitin hinnan määrittämiseksi rakennetun hinnoittelutyökalun ominaisuuksia ja käyttöä. Kova kilpailu ja huomattava kuljetuskustannusten osuus kaikista logistiikkakustannuksista haastavat yritykset kehittämään toimituspalveluistaan yhä tehokkaampia. Jotta niin asiakkaiden, toimittajien kuin kuljetusyritystenkin tarpeet voidaan mahdollisimman hyvin huomioida, on ensisijaisesti tarkasteltava yrityksen omaa toimintaa ja sen kehittymisvalmiuksia kuljetusten hallinnassa. Kuljetuskustannusten muodostumisen havainnollistamiseksi työssä perehdytään raskaan kuljetuskaluston kustannuslaskelmiin eri tekijöineen. Perusteluja kuljetusten yhdistämisen kannattavuudelle haetaan yritysmaailmassa jo toteutetuista esimerkeistä ja kuljetusten yhdistämisen rajoituksista. Kuljetusvirtojen yhdistelyn avulla yrityksen on mahdollista tehostaa logistisia palveluitaan kuljetusten osalta. Taulukkolaskentapohjainen työkalu auttaa tyhjänä ajettavien reittiosuuksien minimoinnissa. Tyhjänä ajon vähentymisen vaikutus näkyy kuljetuskustannusten alenemisena, jonka hyötyjä voidaan pitkällä aikavälillä jakaa useamman sidosryhmän kesken.

Video transcoding in a distributed cloud computing environment

Video transcoding refers to the process of converting a digital video from one format into another format. It is a compute-intensive operation. Therefore, transcoding of a large number of simultaneous video streams requires a large amount of computing resources. Moreover, to handle di erent load conditions in a cost-e cient manner, the video transcoding service should be dynamically scalable. Infrastructure as a Service Clouds currently offer computing resources, such as virtual machines, under the pay-per-use business model. Thus the IaaS Clouds can be leveraged to provide a coste cient, dynamically scalable video transcoding service. To use computing resources e ciently in a cloud computing environment, cost-e cient virtual machine provisioning is required to avoid overutilization and under-utilization of virtual machines. This thesis presents proactive virtual machine resource allocation and de-allocation algorithms for video transcoding in cloud computing. Since users' requests for videos may change at di erent times, a check is required to see if the current computing resources are adequate for the video requests. Therefore, the work on admission control is also provided. In addition to admission control, temporal resolution reduction is used to avoid jitters in a video. Furthermore, in a cloud computing environment such as Amazon EC2, the computing resources are more expensive as compared with the storage resources. Therefore, to avoid repetition of transcoding operations, a transcoded video needs to be stored for a certain time. To store all videos for the same amount of time is also not cost-e cient because popular transcoded videos have high access rate while unpopular transcoded videos are rarely accessed. This thesis provides a cost-e cient computation and storage trade-o strategy, which stores videos in the video repository as long as it is cost-e cient to store them. This thesis also proposes video segmentation strategies for bit rate reduction and spatial resolution reduction video transcoding. The evaluation of proposed strategies is performed using a message passing interface based video transcoder, which uses a coarse-grain parallel processing approach where video is segmented at group of pictures level.

Twitch-palvelun katsomiseen tarkoitetun Windows Store -sovelluksen toteutus

Tämä työ kertoo Twitch.tv-palvelun videolähetyksien katsomiseen tarkoitetun sovelluksen kehittämisestä. Sovellus on tarkoitettu tablet-laitteille, jotka käyttävät Windows 8 -käyttöjärjestelmää. Tarkoituksena on mahdollistaa palvelun käyttäminen ilman selainta suoraan Windows App Store -sovelluksen kautta. Toteutuksessa keskitytään tutkimaan Microsoftin työkaluja ohjelmistonkehitykseen Windowsille, Twitch:n tarjoaman rajapinnan käyttöä ja käyttömahdollisuuksia. Työssä kerrotaan näiden työkalujen rajoittuneisuudesta ja tästä aiheutuvista ongelmista edellä kuvattua sovellusta kehittäessä. Ohjelmistossa panostetaan käytettävyyteen erityisesti tablet-laitteen näkökulmasta, käyttöliittymän suunnittelussa otetaan huomioon yhtenevä ulkonäkö ja Metro UI:n tyyli.

Mobiilialan Start-up -yrityksen jakelukanavan valinta

Diplomityössä tutkitaan mobiilisovellusten keskitettyjä jakelukanavia Start-up – yritysten näkökulmasta. Työssä selvitetään, mitkä tekijät vaikuttavat Start-up – yrityksen jakelukanavan valintaan ja millä perusteilla valinta tehdään. Työn tuloksena saatiin 318 sovelluskehittäjän arvio kymmeneen valintakriteeriin. Merkittävin yksittäinen tekijä Start-up –yrityksille on laitekannan koko. Lisäksi Start-up –yritykset arvostavat muita enemmän sovellusten löydettävyyttä, odotettuja tulovirtoja ja omaa asiantuntemustansa. Mielipiteet Start-up –yritysten kesken jakaa kuitenkin valittu jakelukanava. Suurin yksittäinen päätöskriteeri on markkinatutkimus, yksin tai yhdessä media- ja lehdistötietojen kanssa.