The rapid growth of centralised social media platforms such as Twitter and Facebook has raised concerns about privacy and the concentration of power held by the companies behind these services. In response, decentralised social media platforms have emerged as alternatives, forming federations of various instances without a single owner. However, these decentralised platforms have faced challenges with centralisation, as users tend to gather on larger instances. This paper examines Mastodon, one of the most popular decentralised platforms, to explore whether its onboarding flow and website design can be modified to encourage less centralisation. The study maps Mastodon's onboarding flow and identifies potential modifications to mitigate centralisation. Additionally, a new design for the official website is proposed. User tests involving five participants were conducted to evaluate the effectiveness of these changes. The results indicate that modifying the design can influence users to choose smaller servers. One effective modification is randomising the order in which servers are presented, eliminating the advantage of larger servers. Another proposed change is to improve user awareness about how feeds and interactions on Mastodon spans servers, enabling users to interact beyond their own server and removing a motivation for choosing a larger one. But the impact of this information on user behaviour remains inconclusive in the user tests. Overall, this research suggests that through design modifications, Mastodon can encourage users to select smaller servers and foster a more decentralised social media environment. / Den snabba tillväxten av centraliserade sociala medieplattformar som Twitter och Facebook har väckt oro över personlig integritet och koncentrationen av makt hos företagen bakom dessa tjänster. Som svar har decentraliserade sociala medieplattformar dykt upp, där plattformen består av en federation av olika instanser utan en enda ägare. Dessa decentraliserade plattformar har dock stött på utmaningar med centralisering eftersom användare tenderar att samlas på större instanser. Den här rapporten undersöker Mastodon, en av de mest populära decentraliserade plattformarna, för att undersöka om dess onboardingflöde och designen av deras webbplats kan modifieras för att uppmuntra mindre centralisering. Studien kartlägger Mastodons nuvarande onboardingflöde och identifierar potentiella ändringar som kan mildra centraliseringen. Dessutom föreslås en ny design för den officiella webbplatsen. Användartester med fem deltagare genomfördes för att utvärdera effektiviteten av dessa förändringar. Resultaten indikerar att den modifierade designen kan påverka användare och få dem att välja mindre servrar. En effektiv förändring är att randomisera ordningen i vilken servrar presenteras, vilket eliminerar fördelen större servrar har i hur synliga de är. En annan föreslagen förändring är att förbättra användarnas medvetenhet om att flöden och interaktioner på Mastodon sträcker sig över servrar, vilket gör det möjligt för användare att interagera utanför sin egen server och tar bort ett av motiven användare har för att välja en större server. Vilken effekt det här har på användarnas beteende när det gäller deras val av server var dock oklart i användartesterna som utfördes. Sammantaget tyder denna undersökning på att Mastodon genom designändringar potentiellt kan uppmuntra användare att välja mindre servrar och främja en mer decentraliserad miljö för sociala media.

For a general J wheeled mobile platform capable of up to 3-Degrees-Of-Freedom (DOF) planar motion, there are up to 2J independent input parameters yet the output of the planar platform is specified with only three independent parameters. Currently, the motion synthesis for such platforms is done with a Jacobian based “pseudo” inverse that uses a rectangular matrix for Jacobian. However, a mobile platform is a parallel mechanism and has a more direct solution to the inverse kinematics problem. To this effect, we propose a physical methodology for kinematic modeling of multi-wheeled mobile platforms using Instant Centers (IC) to describe the kinematic state of all system points up to the kth order using a generalized algebraic formulation. This is achieved by using a series of ICs (velocity, acceleration, jerk, etc.) where each point in the system has a time state with its magnitude proportional to the radial distance of the point from the associated IC and at a constant angle relative to that radius. The use of IC’s for mobile platform kinematics is not new, however we present a completely generalized and extensive formulation that also treats the higher order kinematics. To the best of our knowledge, this is the first time the third and higher order ICs have been presented in the literature. The components of this research effort are: (i) extension of the theory of instantaneous invariants to the higher order motion by generalizing the theory to any order, (ii) studying some special case 1-DOF, 2-DOF motions to understand the physical nature of the higher order ICs, (iii) applying the results of (i) and (ii) to the motion synthesis of planar, wheeled mobile platforms by first categorizing them into four distinct categories, and (iv) studying the dynamic model of a representative mobile platform to emphasize the importance of wheel dynamics and traction parameters on the performance of the mobile platform. The IC based formulation presents a concise expression for a general order time state of a general point on the rigid body with the magnitude and direction separated and identified. We showed that the method based on instant centers provides a straightforward and yet physically intuitive way to synthesize a general kth order planar motion of mobile platforms. The study of special case 1-DOF/2-DOF motions emphasized the geometric nature of the higher order ICs and also helped understand the influence of instantaneous kinematic states (such as angular velocity _, angular acceleration, _, etc.) on the various ICs. The application of this theory to planar mobile platform allowed us to categorize the platforms based on their dexterity and to generalize the motion synthesis to some extent. The study of the dynamic model of a representative mobile platform showed us that the redundant inputs (2J inputs versus 3 outputs) in this case may be employed to sustain and manage the uncertainties and nonlinearities in the wheel ground interaction. / text

Os estudos de Governança de Cadeias Globais de Valor (CGVs) analisaram um grande espectro indústrias nos últimos 20 anos, mas a pesquisa de CGV em indústrias de bens de informação ainda é limitado. Cartões de crédito, sistemas operacionais, jogos digitais e aplicativos móveis são exemplos de indústrias que possuem provedores de plataforma, que mediam as interações entre fornecedores e consumidores. Nos últimos anos, o desenvolvimento de plataformas digitais em indústrias tradicionais possibilitou movimentos disruptivos conhecidos como uberização.Os relacionamentos em plataformas são desenhados para serem multilaterais e possuírem efeitos de rede para atrair um maior volume de participantes, o que muda a natureza da coordenação em relação às cadeias tradicionais baseadas em relacionamentos bilaterais sucessivos. Do ponto de vista normativo, as plataformas são baseadas convenção de projetos, típica do \"novo espírito do capitalismo\", cuja lógica de justificação ainda não incorporada no referencial de governança de CGVs. Este trabalho propõe governança por plataforma como um novo tipo de governança, conciliando as abordagens de coordenação e de normatização. A indústria de jogos digitais foi escolhida por ter simultaneamente características de plataforma tecnológica e de distribuição, enfatizadas respectivamente na literatura sobre plataformas industriais e multilaterais. Métodos mistos foram utilizados para a pesquisa em três países (Coreia do Sul, Finlândia e Brasil): questionários aplicados a 235 desenvolvedores de jogos digitais, 73 entrevistas com desenvolvedores, publishers e gestores públicos, e 6 entrevistas com representantes de plataformas, além de pesquisa documental sobre a indústria global. A análise confirmou a importância dos efeitos de rede e que a governança por plataformas possui simultaneamente características de governança presentes em tipos já estabelecidos na literatura e também características distintivas, tanto nos aspectos de coordenação como nos aspectos normativos. Confirmou ainda a aderência da convenção de projetos para compreender este tipo de governança. / Global Value Chain (GVC) Governance studies analyzed a great spectrum of industries last 20 years, but GVC research on information goods industries and the impact of the internet on GVC coordination and normalization is limited.Credit Cards, Operational Systems, Digital Games and Mobile Applications are some classic examples of industries that have platform providers, which mediate suppliers and consumers\' interactions. In recent years, the development of digital platforms in traditional industries possible disruptive movements, known as uberization. Relationships platforms are designed to be multilateral and have network effects to attract a greater volume of participants, which changes the nature of coordination in relation to traditional chains based in successive bilateral relationships. From a normative point of view, the platforms are based on the project convention, typical of the \"new spirit of capitalism\", which justification logic not yet incorporated into the GVCs governance framework. This work proposes governance through platform as a new type of governance and combining the approaches of coordination and standardization. The digital games industry was chosen because both have technology platform characteristics and distribution, respectively emphasized in the literature on industrial and multilateral platforms. Mixed methods were used for research in three countries (South Korea, Finland and Brazil): questionnaires given to 235 developers of digital games, 73 interviews with developers, publishers and public managers, and 6 interviews with representatives of platforms and research documentary on the global industry. The analysis confirmed the importance of network effects and that the governance platform has simultaneously governance characteristics present in types already established in the literature and distinctive characteristicsin both the coordination aspects as the normative aspects. It also confirmed the adherence to the project convention to understand this type of governance.

Torpedo-shaped anchors serve as foundations for risers and floating structures in the deep-water marine environment. Such cone-tipped, cylindrical steel pipes, ballasted with concrete and scrap metal, penetrate the seabed by the kinetic energy they acquire during free fall. Estimation of the embedment depth is a crucial part of the design process in that the pull-out capacity is strongly dependent on the strength of the surrounding soil. This dissertation presents the development of a procedure based on a computational fluid dynamics (CFD) model for the prediction of the embedment depth of torpedo anchors. By means of a representation of the soil as a viscous fluid, the CFD model leads not only to the resisting forces on the anchor but the distributions of pressure and shear in the soil as well. These distributions are then imported in another computational tool for finite-element (FE) analysis of coupled deformation and fluid flow in porous media for further simulations of reconsolidation of the soil next to the anchor and, ultimately, short-term and long-term capacity estimation. This dissertation presents CFD results for torpedo-anchor installation in soil, comparisons with experimental data and, finally, results from FE analysis of soil reconsolidation and anchor pull-out. / text

Os estudos de Governança de Cadeias Globais de Valor (CGVs) analisaram um grande espectro indústrias nos últimos 20 anos, mas a pesquisa de CGV em indústrias de bens de informação ainda é limitado. Cartões de crédito, sistemas operacionais, jogos digitais e aplicativos móveis são exemplos de indústrias que possuem provedores de plataforma, que mediam as interações entre fornecedores e consumidores. Nos últimos anos, o desenvolvimento de plataformas digitais em indústrias tradicionais possibilitou movimentos disruptivos conhecidos como uberização.Os relacionamentos em plataformas são desenhados para serem multilaterais e possuírem efeitos de rede para atrair um maior volume de participantes, o que muda a natureza da coordenação em relação às cadeias tradicionais baseadas em relacionamentos bilaterais sucessivos. Do ponto de vista normativo, as plataformas são baseadas convenção de projetos, típica do \"novo espírito do capitalismo\", cuja lógica de justificação ainda não incorporada no referencial de governança de CGVs. Este trabalho propõe governança por plataforma como um novo tipo de governança, conciliando as abordagens de coordenação e de normatização. A indústria de jogos digitais foi escolhida por ter simultaneamente características de plataforma tecnológica e de distribuição, enfatizadas respectivamente na literatura sobre plataformas industriais e multilaterais. Métodos mistos foram utilizados para a pesquisa em três países (Coreia do Sul, Finlândia e Brasil): questionários aplicados a 235 desenvolvedores de jogos digitais, 73 entrevistas com desenvolvedores, publishers e gestores públicos, e 6 entrevistas com representantes de plataformas, além de pesquisa documental sobre a indústria global. A análise confirmou a importância dos efeitos de rede e que a governança por plataformas possui simultaneamente características de governança presentes em tipos já estabelecidos na literatura e também características distintivas, tanto nos aspectos de coordenação como nos aspectos normativos. Confirmou ainda a aderência da convenção de projetos para compreender este tipo de governança. / Global Value Chain (GVC) Governance studies analyzed a great spectrum of industries last 20 years, but GVC research on information goods industries and the impact of the internet on GVC coordination and normalization is limited.Credit Cards, Operational Systems, Digital Games and Mobile Applications are some classic examples of industries that have platform providers, which mediate suppliers and consumers\' interactions. In recent years, the development of digital platforms in traditional industries possible disruptive movements, known as uberization. Relationships platforms are designed to be multilateral and have network effects to attract a greater volume of participants, which changes the nature of coordination in relation to traditional chains based in successive bilateral relationships. From a normative point of view, the platforms are based on the project convention, typical of the \"new spirit of capitalism\", which justification logic not yet incorporated into the GVCs governance framework. This work proposes governance through platform as a new type of governance and combining the approaches of coordination and standardization. The digital games industry was chosen because both have technology platform characteristics and distribution, respectively emphasized in the literature on industrial and multilateral platforms. Mixed methods were used for research in three countries (South Korea, Finland and Brazil): questionnaires given to 235 developers of digital games, 73 interviews with developers, publishers and public managers, and 6 interviews with representatives of platforms and research documentary on the global industry. The analysis confirmed the importance of network effects and that the governance platform has simultaneously governance characteristics present in types already established in the literature and distinctive characteristicsin both the coordination aspects as the normative aspects. It also confirmed the adherence to the project convention to understand this type of governance.

The rising trend of over consumption has led to threatening environmental consequences. A solution to this would be collaborative consumption, as it promotes environmentally friendly sharing behaviors. Collaborative consumption can be enabled with digital tools, such as digital sharing platforms. The purpose of this study is to generate knowledge about how digital sharing platforms can be successfully established in order to build a good foundation for collaborative consumption. This qualitative research, influenced by grounded theory as a method, aims to explore the question “what are the barriers for establishing a digital sharing platform?”. Based on related research and by investigating a digital sharing platform called Umigo, we conducted six semi-structured interviews based on three technological frames and identified multiple barriers. With this research we make two main contributions. Our first contribution is that digital sharing platforms are unique in comparison to other platform types and should therefore be studied further. We also found an overview of the barriers that could prevent the successful establishment of digital sharing platforms.

While we are already used to see more than 1,000 cores within a single machine, the next processing platforms for database engines will be heterogeneous with built-in GPU-style processors as well as specialized FPGAs or chips with domain-specific instruction sets. Moreover, the traditional volatile as well as the upcoming non-volatile RAM with capacities in the 100s of TBytes per machine will provide great opportunities for storage engines but also call for radical changes on the architecture of such systems. Finally, the emergence of economically affordable, high-speed/low-latency interconnects as a basis for rack-scale computing is questioning long-standing folklore algorithmic assumptions but will certainly play an important role in the big picture of building modern data management platforms. In this talk, we will try to classify and review existing approaches from a performance, robustness, as well as energy efficiency perspective and pinpoint interesting starting points for further research activities.

China’s import cross-border e-commerce (CICBEC) business model differs from other online shopping business models in both the participators and transaction processes. Government as an important participator has greatly promoted the healthy and rapid development of this business model. As a vital topic in all kinds of businesses, customer trust is also a core research topic in online shopping. Many scholars have studied customer trust in traditional online shopping while few of them focused on cross-border online shopping, let alone the CICBEC business model. The government is a new participator, whose contribution on customer trust is not clear. Also, other known variables’ influences on customer trust are still worthy of discussion. This research aims to address existing research gap by contributing to Lee and Turban (2001)’s Customer Trust in Internet Shopping (CTIS) Model and constructing a new customer trust model. A number of influencing factors of customer trust were defined and tested in this research. It shows that influencing factors from four participators, the e-retailers, e- commerce platforms, government and third-parties, have a significant correlation with customer trust. The final results show that order fulfillment, government actions, e-retailer reputation, information quality, e-commerce platform security and e-commerce platform reputation have significant influences on customer trust.

The objective of this PhD research was the development of novel 3D interactive medical platforms for medical image analysis, simulation and visualisation, with a focus on oncology images to support clinicians in managing the increasing amount of data provided by several medical image modalities. DoctorEye and Automatic Tumour Detector platforms were developed through constant interaction and feedback from expert clinicians, integrating a number of innovations in algorithms and methods, concerning image handling, segmentation, annotation, visualisation and plug-in technologies. DoctorEye is already being used in a related tumour modelling EC project (ContraCancrum) and offers several robust algorithms and tools for fast annotation, 3D visualisation and measurements to assist the clinician in better understanding the pathology of the brain area and define the treatment. It is free to use upon request and offers a user friendly environment for clinicians as it simplifies the implementation of complex algorithms and methods. It integrates a sophisticated, simple-to-use plug-in technology allowing researchers to add algorithms and methods (e.g. tumour growth and simulation algorithms for improving therapy planning) and interactively check the results. Apart from diagnostic and research purposes, it supports clinical training as it allows an expert clinician to evaluate a clinical delineation by different clinical users. The Automatic Tumour Detector focuses on abdominal images, which are more complex than those of the brain. It supports full automatic 3D detection of kidney pathology in real-time as well as 3D advanced visualisation and measurements. This is achieved through an innovative method implementing Templates. They contain rules and parameters for the Automatic Recognition Framework defined interactively by engineers based on clinicians’ 3D Golden Standard models. The Templates enable the automatic detection of kidneys and their possible abnormalities (tumours, stones and cysts). The system also supports the transmission of these Templates to another expert for a second opinion. Future versions of the proposed platforms could integrate even more sophisticated algorithms and tools and offer fully computer-aided identification of a variety of other organs and their dysfunctions.

<p>What role do state party organizations play in twenty-first century American politics? What is the nature of the relationship between the state and national party organizations in contemporary elections? These questions frame the three studies presented in this dissertation. More specifically, I examine the organizational development of the state party organizations and the strategic interactions and connections between the state and national party organizations in contemporary elections. </p><p>In the first empirical chapter, I argue that the Internet Age represents a significant transitional period for state party organizations. Using data collected from surveys of state party leaders, this chapter reevaluates and updates existing theories of party organizational strength and demonstrates the importance of new indicators of party technological capacity to our understanding of party organizational development in the early twenty-first century. In the second chapter, I ask whether the national parties utilize different strategies in deciding how to allocate resources to state parties through fund transfers and through the 50-state-strategy party-building programs that both the Democratic and Republican National Committees advertised during the 2010 elections. Analyzing data collected from my 2011 state party survey and party-fund-transfer data collected from the Federal Election Commission, I find that the national parties considered a combination of state and national electoral concerns in directing assistance to the state parties through their 50-state strategies, as opposed to the strict battleground-state strategy that explains party fund transfers. In my last chapter, I examine the relationships between platforms issued by Democratic and Republican state and national parties and the strategic considerations that explain why state platforms vary in their degree of similarity to the national platform. I analyze an extensive platform dataset, using cluster analysis and document similarity measures to compare platform content across the 1952 to 2014 period. The analysis shows that, as a group, Democratic and Republican state platforms exhibit greater intra-party homogeneity and inter-party heterogeneity starting in the early 1990s, and state-national platform similarity is higher in states that are key players in presidential elections, among other factors. Together, these three studies demonstrate the significance of the state party organizations and the state-national party partnership in contemporary politics.</p> / Dissertation