A Study of Multicast Performance in IEEE 802.11 Wireless Local Area Networks

Langattomat lähiverkot ovat yleistyneet ja monin paikoin niillä pyritään täysin korvaamaan perinteiset kaapeloidut verkot. Samalla verkoissa välitettävät palvelut monipuolistuvat. Etenkin interaktiivisten sisältöjen ja viiveriippuvaisten palvelujen välittämisessä korostuvat verkolle asettavat vaatimukset suorituskyvystä ja palveluntasosta. Radiotaajuuksilla tapahtuva tiedonsiirto on ongelmallista siirtomedian jaetun luonteen vuoksi. Käytettäessä ympärisäteileviä antenneja jokainen kantomatkan päässä oleva asema kuulee lähetyksen, vaikkei se olisi sille suunnattu. Tämä luo turvallisuusongelman, mutta lisäksi heikentää tehokkuutta, koska nykyisellä antenniteknologialla vain yksi asema kerrallaan voi lähettää häiriöttä kantoalueellaan. Täsmälähetykset yhden lähteen ja useiden kohteiden välillä luovat erillisiä siirtolinkkejä. Olisi luontevampaa luoda yksi lähetysvirta, johon useat vastaanottajat voivat kytkeytyä. Kaistan säästön vastapainona on tarve luoda ja ylläpitää näitä yhteyksiä. Käyttäjien liikkuvuuden ja siirtotien vaihtelevien ominaisuuksien vuoksi langattoman verkon rakenne ja rajat ovat epäselviä. Näihin haasteisiin on vastattava sekä protokolla- että sovellustasolla. Tässä tutkielmassa käydään ensin läpi IEEE 802.11 -standardin mukaisen langattoman verkon perusteet ja sen ominaisuuksiin liittyvät tyypilliset ongelmakohdat. Yleis- ja ryhmälähetyksiä tarkastellaan ensin perinteisessä IEEE 802.3 standardin mukaisessa langallisessa lähiverkossa ja selvitetään, miten vastaavat ominaisuudet toteutuvat IEEE 802.11 standardien mukaisissa langattomissa verkoissa. Käyttötapaustutkimuksissa keskitytään rajatussa ympäristössä tapahtuviin ryhmälähetyksiin. Erityisesti tutkitaan langattomien ryhmälähetysten käyttökelpoisuutta sekä langattoman ympäristön asettamia erityisvaatimuksia.

Helsinki hub – new traffic flows and business networks

This thesis is the Logistics Development Forum's assignment and the work dealing with the development of the Port of Helsinki as part of Helsinki hub. The Forum aims to develop logistics efficiency through public-private co-operation and development of the port is clearly dependent on both factors. Freight volumes in the Port of Helsinki are the biggest single factor in hub and, therefore, the role of the port of the entire hub development is strong. The aim is to look at how the port will develop as a result of changes in the foreign trade of Finland and the Northern European logistics trends in 25 years time period. Work includes the current state analysis and scenario work. The analyses are intended to find out, which trends are the most important in the port volume development. The change and effect of trends is examined through scenarios based on current state. Based on the work, the structure of Finnish export industry and international demand are in the key role in the port volume development. There is significant difference between demands of Finnish exporting products in different export markets and the development between the markets has different impacts on the port volumes by mass and cargo type. On the other hand, the Finnish economy is stuck in a prolonged recession and competition between ports has become a significant factor in the individual port's volume development. Ecological valuesand regulations have changed the competitive landscape and maritime transport emissions reductions has become an important competitive factor for short routes in the Baltic Sea, such as in the link between Helsinki and Tallinn.

Relay protection in active distribution networks

Increasingly growing share of distributed generation in the whole electrical power system’s generating system is currently a worldwide tendency, driven by several factors, encircling mainly difficulties in refinement of megalopolises’ distribution networks and its maintenance; widening environmental concerns adding to both energy efficiency approaches and installation of renewable sources based generation, inherently distributed; increased power quality and reliability needs; progress in IT field, making implementable harmonization of needs and interests of different-energy-type generators and consumers. At this stage, the volume, formed by system-interconnected distributed generation facilities, have reached the level of causing broad impact toward system operation under emergency and post-emergency conditions in several EU countries, thus previously implementable approach of their preliminary tripping in case of a fault, preventing generating equipment damage and disoperation of relay protection and automation, is not applicable any more. Adding to the preceding, withstand capability and transient electromechanical stability of generating technologies, interconnecting in proximity of load nodes, enhanced significantly since the moment Low Voltage Ride-Through regulations, followed by techniques, were introduced in Grid Codes. Both aspects leads to relay protection and auto-reclosing operation in presence of distributed generation generally connected after grid planning and construction phases. This paper proposes solutions to the emerging need to ensure correct operation of the equipment in question with least possible grid refinements, distinctively for every type of distributed generation technology achieved its technical maturity to date and network’s protection. New generating technologies are equivalented from the perspective of representation in calculation of initial steady-state short-circuit current used to dimension current-sensing relay protection, and widely adopted short-circuit calculation practices, as IEC 60909 and VDE 0102. The phenomenon of unintentional islanding, influencing auto-reclosing, is addressed, and protection schemes used to eliminate an sustained island are listed and characterized by reliability and implementation related factors, whereas also forming a crucial aspect of realization of the proposed protection operation relieving measures.

Benefits of a low-cost one-phase current distortion detection device in appliance supply in low-voltage residential networks

In this bachelor’s thesis are examined the benefits of current distortion detection device application in customer premises low voltage networks. The purpose of this study was to find out if there are benefits for measuring current distortion in low-voltage residential networks. Concluding into who can benefit from measuring the power quality. The research focuses on benefits based on the standardization in Europe and United States of America. In this research, were also given examples of appliances in which current distortion detection device could be used. Along with possible illustration of user interface for the device. The research was conducted as an analysis of the benefits of current distortion detection device in residential low voltage networks. The research was based on literature review. The study was divided to three sections. The first explain the reasons for benefitting from usage of the device and the second portrays the low-cost device, which could detect one-phase current distortion, in theory. The last section discuss of the benefits of usage of current distortion detection device while focusing on the beneficiaries. Based on the result of this research, there are benefits from usage to the current distortion detection device. The main benefitting party of the current distortion detection device was found to be manufactures, as they are held responsible of limiting the current distortion on behalf of consumers. Manufactures could adjust equipment to respond better to the distortion by having access to on-going current distortion in network. The other benefitting party are system operators, who would better locate distortion issues in low-voltage residential network to start prevention of long-term problems caused by current distortion early on.

Pretraining Convolutional Neural Networks for Visual Recognition

Convolutional Neural Networks (CNN) have become the state-of-the-art methods on many large scale visual recognition tasks. For a lot of practical applications, CNN architectures have a restrictive requirement: A huge amount of labeled data are needed for training. The idea of generative pretraining is to obtain initial weights of the network by training the network in a completely unsupervised way and then fine-tune the weights for the task at hand using supervised learning. In this thesis, a general introduction to Deep Neural Networks and algorithms are given and these methods are applied to classification tasks of handwritten digits and natural images for developing unsupervised feature learning. The goal of this thesis is to find out if the effect of pretraining is damped by recent practical advances in optimization and regularization of CNN. The experimental results show that pretraining is still a substantial regularizer, however, not a necessary step in training Convolutional Neural Networks with rectified activations. On handwritten digits, the proposed pretraining model achieved a classification accuracy comparable to the state-of-the-art methods.

The role of diaspora networks in opportunity exploitation by ethnic entrepreneurs in Finland

The thesis explores the role of diaspora network in opportunity exploitation by ethnic entrepreneurs in Finland. The purpose of this study is to how ethnic entrepreneurs in Finland can exploit diaspora networks and how significant support of these networks in comparison with governmental and other official institutional support. Increased mobility of the global population and number of immigrants all around the world contribute into interest of academics to this topic. At the same time, in comparison with other European countries for Finland this phenomenon is new. However, increasing number of immigrants add to academic interest to this topic. The theoretical background of this thesis consists of the collection of studies done on diaspora networks and ethnic entrepreneurs as internationally as in Finland. The concept of cooperation between diaspora and ethnic entrepreneurs describes how diaspora can support ethnic entrepreneur and emphasize importance of diaspora ties for business. At the end of the theoretical section theoretical a special grid was proposed as summary of the academic literature review. The empirical research for this study is based on the interviews with five ethnic entrepreneurs in Finland. Empirical data was analyzed and compared with the similar studies done internationally. During the interviews analyses were stressed aspects of the significance of governmental and other official institutional support. During the interviews analyses were stressed aspects of the significance of the governmental and other official institutional support. According to the main findings diaspora can play positive and in some cases crucial role in the business of ethnic entrepreneurs in Finland. Moreover, diaspora can be a facilitator of internationalization of ethnic entrepreneurs. At the same time, there are several factors which might increase or decrease role of diaspora. The ways of the utilization of diaspora network were combined in the empirical grid. The study enhance understanding of the challenges of ethnic entrepreneurs and provides certain recommendations for the policy makers, ethnic entrepreneurs and managers of official institutions involved in cooperation with ethnic entrepreneurs

The Role Of Social Networks In New Venture Internationalization: Case Of Russian And Finnish Firms

The purpose of current master thesis research is to investigate the role of social networks in internationalization of Russian and Finnish firms. Literature review of existing empirical researches on the topic is conducted in order to identify the gap, which is fulfilled by empirical research of 4 Russian and 1 Finnish firm that have established international operations no later than 8 years since their foundation. In-depth semi-structured interviews have shown that business network has been an influencing factor in firms’ internationalization and that even if social network is not the driver of internationalization, it becomes important when a company has established international presence and is working on its enlargement. The study has both theoretical and practical contribution by contributing to research of Russian and Finnish firms’ internationalization and by showing examples of successful foreign market entry of companies from different industries. General practical implication of current thesis is that it shows the efficient ways of entrepreneurs’ social network usage in business development in international scope.

Managing Finnish-Russian Business Relationships and Networks During Conflicts

This thesis examines management of business relationships during conflicts. The context of this study is the international political conflict which started in 2013 and is still affecting international trade relations in 2016. More specifically, this study researches the effects of the conflict in Finnish-Russian trade. The research aim is to identify the implications of a political conflict in the Finnish-Russian business relationships and networks. Furthermore, the study will explore how does a company adapt or overcome the challenges and barriers posed by the international business environment. This research combines relevant theories in management of business relationships and networks in order to review the research data through a critical research frame. The theoretical frameworks are different structures of business relationship development processes, various stages of interaction, and characteristics and functions of business relationships. Moreover, this study will examine the effect of interdependency, commitment and trust in trade relations. Also, what are the important exchange processes and how do these processes affect business relationship and overall performance of joint business operations. Qualitative single case study method was used in this research. Case company was a Finnish multinational company. To understand the changes, the data was collected and analysed through process research approach by pattern-matching and drawing temporal bracketing over two different periods of time, first period in years 2011-2013 and second period in years 2014-2016. Empirical data was collected through a semi-structured interview and additional data was collected from internal and external secondary data sources. The findings of the study confirmed the relationship between trade and conflict. However, the effects are not significant for a company in grocery retail industry which has had earlier experience in Russia and has managed its business relationships and operations effectively. Macroeconomic factors affect companies operating in foreign dynamic markets and in order to sustain changes and to adapt, companies should invest in their business relationships. Trust-based relationships and a higher level of commitment allow companies to have more efficient and beneficial outcomes before and during uncertainty. Furthermore, well-maintained and coordinated business relationships provide the ability to adapt and overcome challenges during uncertainty. Such relationships have information, financial and social exchange processes which allow the partnering firms to have successful business relationship management in dynamic market environments.

On the edge : exploring homeless women's social networks

This thesis aims to uncover the ways that previously homeless women in the Niagara region are able (or unable) to rely on friends, family and service providers in times of crisis (homelessness and poverty). Eleven women were interviewed and their experiences indicate that social networks cannot take the place of comprehensive and inclusive social policy. Time and time again, their stories showed that they were left negotiating the detritus of neo-liberal policies.

Development of packaging cell lines for rescuing BAV2 viral vectors

The construction of adenovirus vectors for cloning and foreign gene expression requires packaging cell lines that can complement missing viral functions caused by sequence deletions and/or replacement with foreign DNA sequences. In this study, packaging cell lines were designed to provide in trans the missing bovine adenovirus functions, so that recombinant viruses could be generated. Fetal bovine kidney and lUng cells, acquired at the trimester term from a pregnant cow, were tranfected with both digested wild type BAV2 genomic DNA and pCMV-EI. The plasmid pCMV-EI was specifically constructed to express El of BAV2 under the control of the cytomegalovirus enhancer/promoter (CMV). Selection for "true" transformants by continuous passaging showed no success in isolating immortalised cells, since the cells underwent crisis resulting in complete cell death. Moreover, selection for G418 resistance, using the same cells, also did not result in the isolation of an immortalised cell line and the same culture-collapse event was observed. The lack of success in establishing an immortalised cell line from fetal tissue prompted us to transfect a pre-established cell line. We began by transfecting MDBK (Mardin-Dardy bovine kidney) cells with pCMV-El-neo, which contain the bacterial selectable marker neo gene. A series of MDBK-derived cell lines, that constitutively express bovine adenoviral (BAV) early region 1 (El), were then isolated. Cells selected for resistance to the drug G418 were isolated collectively for full characterisation to assess their suitability as packaging cell lines. Individual colonies were isolated by limiting dilution and further tested for El expression and efficiency of DNA uptake. Two cell lines, L-23 and L-24, out of 48 generated foci tested positive for £1 expression using Northern Blot analysis. DNA uptake studies, using both lipofectamine and calcium phosphate methods, were performed to compare these cells, their parental MDBK cells, 8 and the unrelated human 293 cells as a benchmark. The results revealed that the new MDBKderived clones were no more efficient than MDBK cells in the transient expression of transfected DNA and that they were inferior to 293 cells, when using lacZ as the reporter gene. In view of the inherently poor transfection efficiency of MDBK cells and their derivatives, a number of other bovine cells were investigated for their potential as packaging cells. The cell line CCL40 was chosen for its high efficiency in DNA uptake and subsequently transfected with the plasmid vector pCMV El-neo. By selection with the drug G418, two cell lines were isolated, ProCell 1 and ProCell 2. These cell lines were tested for El expression, permissivity to BAV2 and DNA uptake efficiency, revealing a DNA uptake efficiency of 37 % , comparable to that of CCL40. Attempts to rescue BAV2 mutants carrying the lacZ gene in place of £1 or £3 were carried out by co-transfecting wild type viral DNA with either the plasmid pdlElE-Z (which contains BAV2 sequences from 0% to 40.4% with the lacZ gene in place of the £1 region from 1.1% to 8.25%) or with the plasmid pdlE3-5-Z (which contains BAV2 sequences from 64.8% to 100% with the lacZ gene in place of the E3 region from 75.8% to 81.4%). These cotransfections did not result in the generation of a viral mutant. The lack of mutant generation was thought to be caused by the relative inefficiency ofDNA uptake. Consequently, cosBAV2, a cosmid vector carrying the BAV2 genome, was modified to carry the neo reporter gene in place of the £3 region from 75.8% to 81.4%. The use of a single cosmid vector earring the whole genome would eliminate the need for homologous recombination in order to generate a viral vector. Unfortunately, the transfection of cosBAV2- neo also did not result in the generation of a viral mutant. This may have been caused by the size of the £3 deletion, where excess sequences that are essential to the virus' survival might have been deleted. As an extension to this study, the spontaneous E3 deletion, accidently discovered in our viral stock, could be used as site of foreign gene insertion.

Niagara alternative food projects : networks, discourses and nature /

This thesis undertakes an exploration of the nature of alternative food projects in Niagara. A review of various theoretical approaches to the study of food and agriculture, suggests that actor-network theory offers the most useful lens through which to understand these projects. In particular, actor-network theory facilitates non-dualistic theorisations of power and scale and a commitment to the inclusion of non-humans in the 'social' sciences. The research is based on 19 in-depth interviews with actors involved in various urban and rural projects including community supported agriculture, community gardens, chefs using local seasonal food, a winery that grows organically, the good food box, a value-added small business, and organic producers. The analysis consists of four themes. The first analytical section pays special attention to the prominence of agri-tourism in Niagara, and examines the ways in which the projects in the sample interact with agri-tourist networks. In the second section the discussion focuses on the discourses and practices of resistance among Niagara alternative food actors. The participants' interviews suggest there are more discourses of resistance toward agri-tourist than toward dominant food networks. The third section questions commodity chain theorisations of alternative food projects. In particular, this section shows how the inclusion of non-human actors in an analysis confounds conceptualisations of 'short' and 'local' chains. The final analytical section assesses relations of power in Niagara alternative food projects. Three important conclusions arise from this research. First, Niagara alternative food projects cannot be conceptualised as operating at the 'local' scale. Broadening the scope of analysis to include non-human actors, it becomes apparent that these projects actually draw on a variety of extra-local actors. They are at once local and global. Second, the projects in this sample are simultaneously part of alternative, dominant and agri-tourist networks. While Niagara alternative food projects do perform many of the roles characteristic of alternative food systems, they are also involved in practices of development, business, and class distinction. Thus, alternative food networks should not be understood as separate from and in direct opposition to dominant food networks. Despite the second conclusion, this research determines that Niagara alternative food projects have made significant strides in the reworking of power. The projects represented in this thesis do engage in resistant practices and are associated with increased levels ofjustice.

Biochemical and histological investigations of viral localisation in the hypersensitive reaction of Phaselous vulgaris L. var Pinto to tobacco mosaic virus infection

STOBBS, Lorne,W ABSTRACT Biochemical and Histological Investigations of viral localisation in the hypersensitive reaction of Phaseolus vulgaris L. var Pinto to tobacco mosaic virus infection. The infection of Phaseolus vulgaris L. var Pinto with tobacco mosaic virus (TMV) results in the production of distinct necrotic lesions confining the virus to restricted areas of the leaf surface. Biochemical and histological changes in the leaf tissue as a result of infection have been described. Trace accumulations of fluorescent metabolites, detected prior to lesion expression represent metabolites produced, by the cell in response to virus infection. These substances, are considered to undergo oxidation and in diffusing into adjacent cells, react with cellular constituents causing the death of these cells. Such cellular necrosis in advance of infection effectively limits virus spread. Chromatographic studies on extracts from TMV infected Pinto bean leaf tissue suggests that a number of extra-fluorescent metabolites produced on lesion'expression represent end products of phenolic oxidation r,eactionsoccurring earlier in these cells. Inhibition of phenolic oxidation by ascorbate infiltration or elevated temperature treatment resulted in the absence of extra-fluorescent metabolites and the continued movement of virus in the absence of necrosis. Further studies with i ascorbate infiltration indicated that irreversible necrotic events were determined as early as 12 tci 18 hrs after viral inoculation. Histochemical tests indicated that callose formation was initiated at this time, and occurred in response to necrotisation. Inhibition of necrosis by either ascorbate infiltration or elevated temp8rature treatment resulted in the absence of callose deposition. Scanning electron'micrographs of infected tissue revealed severe epidermal and palisade cell damage. Histochemical tests indicated extensive callose formation in cells bordering the lesion, and suggested the role of callose iTh the blockage of intercellular connections limiting virus movement. The significance of these cellular changes is discussed. ii

'What ever happened to breakdancing?' : transnational b-boy/b-girl networks, underground video magazines and imagined affinities

In 1997, Paul Gilroy was able to write: "I have been asking myself, whatever happened to breakdancing" (21), a form of vernacular dance associated with urban youth that emerged in the 1970s. However, in the last decade, breakdancing has experienced a massive renaissance in movies (You Got Served), commercials ("Gotta Have My Pops!") and documentaries (the acclaimed Freshest Kids). In this thesis, 1 explore the historical development of global b-boy/bgirl culture through a qualitative study involving dancers and their modes of communication. Widespread circulation of breakdancing images peaked in the mid-1980s, and subsequently b-boy/b-girl culture largely disappeared from the mediated landscape. The dance did not reemerge into the mainstream of North American popular culture until the late 1990s. 1 argue that the development of major transnational networks between b-boys and b-girls during the 1990s was a key factor in the return of 'b-boying/b-girling' (known formerly as breakdancing). Street dancers toured, traveled and competed internationally throughout this decade. They also began to create 'underground' video documentaries and travel video 'magazines.' These video artefacts circulated extensively around the globe through alternative distribution channels (including the backpacks of traveling dancers). 1 argue that underground video artefacts helped to produce 'imagined affinities' between dancers in various nations. Imagined affinities are identifications expressed by a cultural producer who shares an embodied activity with other practitioners through either mediated texts or travels through new places. These 'imagined affinities' helped to sustain b-boy/b-girl culture by generating visual/audio representations of popularity for the dance movement across geographical regions.

Particle swarm optimization for two-connected networks with bounded rings

The Two-Connected Network with Bounded Ring (2CNBR) problem is a network design problem addressing the connection of servers to create a survivable network with limited redirections in the event of failures. Particle Swarm Optimization (PSO) is a stochastic population-based optimization technique modeled on the social behaviour of flocking birds or schooling fish. This thesis applies PSO to the 2CNBR problem. As PSO is originally designed to handle a continuous solution space, modification of the algorithm was necessary in order to adapt it for such a highly constrained discrete combinatorial optimization problem. Presented are an indirect transcription scheme for applying PSO to such discrete optimization problems and an oscillating mechanism for averting stagnation.