Traditional database management systems are designed for general purpose data handling, and fail to work efficiently with time-series data due to characteristics like high volume, rapid ingestion rates, and a focus on temporal relationships. However, what is a best solution is not a trivial question to answer. Hence, this thesis aims to analyze four different Database Management Systems (DBMS) to determine their suitability for managing time series data, with a specific focus on Internet of Things (IoT) applications. The DBMSs examined include PostgreSQL, TimescaleDB, ClickHouse, and InfluxDB. This thesis evaluates query performance across varying dataset sizes and time ranges, as well as the implementational complexity of each DBMS. The benchmarking results indicate that InfluxDB consistently delivers the best performance, though it involves higher implementational complexity and time consumption. ClickHouse emerges as a strong alternative with the second-best performance and the simplest implementation. The thesis also identifies potential biases in benchmarking tools and suggests that TimescaleDB's performance may have been affected by configuration errors. The findings provide significant insights into the performance metrics and implementation challenges of the selected DBMSs. Despite limitations in fully addressing the research questions, this thesis offers a valuable overview of the examined DBMSs in terms of performance and implementational complexity. These results should be considered alongside additional research when selecting a DBMS for time series data. / Traditionella databashanteringssystem är utformade för allmän datahantering och fungerar inte effektivt med tidsseriedata på grund av egenskaper som hög volym, snabba insättningshastigheter och fokus på tidsrelationer. Dock är frågan om vad som är den bästa lösningen inte trivial. Därför syftar denna avhandling till att analysera fyra olika databashanteringssystem (DBMS) för att fastställa deras lämplighet för att hantera tidsseriedata, med ett särskilt fokus på Internet of Things (IoT)-applikationer. De DBMS som undersöks inkluderar PostgreSQL, TimescaleDB, ClickHouse och InfluxDB. Denna avhandling utvärderar sökprestanda över varierande datamängder och tidsintervall, samt implementeringskomplexiteten för varje DBMS. Prestandaresultaten visar att InfluxDB konsekvent levererar den bästa prestandan, men med högre implementeringskomplexitet och tidsåtgång. ClickHouse framstår som ett starkt alternativ med näst bäst prestanda och är enklast att implementera. Studien identifierar också potentiella partiskhet i prestandaverktygen och antyder att TimescaleDB:s prestandaresultat kan ha påverkats av konfigurationsfel. Resultaten ger betydande insikter i prestandamått och implementeringsutmaningar för de utvalda DBMS. Trots begränsningarna i att fullt ut besvara forskningsfrågorna erbjuder studien en värdefull översikt. Dessa resultat bör beaktas tillsammans med ytterligare forskning vid val av ett DBMS för tidsseriedata.

本論文所探討的是利用智慧型行動裝置，如手機、平板電腦，以及未來可能大量普及的穿戴式眼鏡，打造一行動體驗行銷平台，並藉此平台設計一商業模式，使得消費者可以獲得四加一的體驗，包含：娛樂的、美學的、教育的、跳脫現實的，與參與的體驗。而商家在消費者參與遊戲的同時達到了吸客上門的目的，提高了能見度、傳達設計的訊息，同時也提高了購買意願。 此平台提供簡單易懂、自由創作的工具，只要利用智慧型行動裝置即可打造專屬的擴增實境行動服務。消費者可以建立自己所設計的故事與遊戲；商家也可以藉由平台設計遊戲應用軟體，將品牌精神、產品價值融入其中，藉以提高顧客關係，並達到行銷的目的。 / The objective of this study is to report a plan of an innovative business model on mobile devices. The business model is to provide a smart platform for businesses and individuals to conduct experience marketing. Applying the concept of gamification this platform can facilitate the design of the gaming applications and to attract a flow of users to visit the designated locations. This business model makes customers indulging in four plus one experiences including: entertainment, esthetic, educational, escapist, and engagement. The designers of the games can achieve the purpose of raising brand image, delivering key messages, and increasing visits. This platform provides simple and easy-to-understand tools. Users can build their own location-based game applications with augmented reality (AR) technology to enhance the experience of virtual/real challenges. Not only individuals can create their own games but also businesses can develop their own game applications embedded with brand spirit and product value to strengthen customer relationship.

e-Learning is becoming an influential role as an economic method and a flexible mode of study in the institutions of higher education today which has a presence in an increasing number of college and university courses. e-Learning as system of systems is a dynamic and scalable environment. Within this environment, e-learning is still searching for a permanent, comfortable and serviceable position that is to be controlled, managed, flexible, accessible and continually up-to-date with the wider university structure. As most academic and business institutions and training centres around the world have adopted the e-learning concept and technology in order to create, deliver and manage their learning materials through the web, it has become the focus of investigation. However, management, monitoring and collaboration between these institutions and centres are limited. Existing technologies such as grid, web services and agents are promising better results. In this research a new architecture has been developed and adopted to make the e-learning environment more dynamic and scalable by dividing it into regional data grids which are managed and monitored by agents. Multi-agent technology has been applied to integrate each regional data grid with others in order to produce an architecture which is more scalable, reliable, and efficient. The result we refer to as Regionally Distributed Architecture for Dynamic e-Learning Environment (RDADeLE). Our RDADeLE architecture is an agent-based grid environment which is composed of components such as learners, staff, nodes, regional grids, grid services and Learning Objects (LOs). These components are built and organised as a multi-agent system (MAS) using the Java Agent Development (JADE) platform. The main role of the agents in our architecture is to control and monitor grid components in order to build an adaptable, extensible, and flexible grid-based e-learning system. Two techniques have been developed and adopted in the architecture to build LOs' information and grid services. The first technique is the XML-based Registries Technique (XRT). In this technique LOs' information is built using XML registries to be discovered by the learners. The registries are written in Dublin Core Metadata Initiative (DCMI) format. The second technique is the Registered-based Services Technique (RST). In this technique the services are grid services which are built using agents. The services are registered with the Directory Facilitator (DF) of a JADE platform in order to be discovered by all other components. All components of the RDADeLE system, including grid service, are built as a multi-agent system (MAS). Each regional grid in the first technique has only its own registry, whereas in the second technique the grid services of all regional grids have to be registered with the DF. We have evaluated the RDADeLE system guided by both techniques by building a simulation of the prototype. The prototype has a main interface which consists of the name of the system (RDADeLE) and a specification table which includes Number of Regional Grids, Number of Nodes, Maximum Number of Learners connected to each node, and Number of Grid Services to be filled by the administrator of the RDADeLE system in order to create the prototype. Using the RST technique shows that the RDADeLE system can be built with more regional grids with less memory consumption. Moreover, using the RST technique shows that more grid services can be registered in the RDADeLE system with a lower average search time and the search performance is increased compared with the XRT technique. Finally, using one or both techniques, the XRT or the RST, in the prototype does not affect the reliability of the RDADeLE system.

近年來，電子商務飛速發展，已取得長足進步。電子商務可以高效利用有限資源，加快商業週期循環，節省時間、降低成本、提高利潤和增強企業競爭力，並以傳統經營方式所無法比擬的優點受到全球關注。因此，電子商務給企業所帶來的影響是非常重要且值得探討。 在電子商務貿易模式中，信息的高效傳遞成為平台上賣方增強競爭力的重要手段。但是過去鮮少有研究以信號理論觀點，切入探討B2B交易平台上賣方信號對買方之吸引力，以及鮮少有研究探討其中是否有其他變數可能會增加或削弱兩者之間的關係。因此本研究旨在探討賣方採用的信號與買方聯繫賣方之可能性的關係，並以企業外部市場化發展程度因素作為干擾變數。 本文共蒐集167家中小企業信息作為研究對象，並以階層回歸作為分析方法，進一步釐清賣方所採用的信號與買方聯繫賣方之可能性之間的關係，並以企業外部市場化發展程度作為干擾變數，研究外部環境情況是否會強化賣方所採用的信號與買方聯繫賣方之可能性之間的關係，補充過去文獻鮮少探討之觀點。冀望本研究結果能為平台賣方之決策者在考慮如何運營，提供一些參考與建議。

Thesis (MA)--Stellenbosch University, 2015 / ENGLISH ABSTRACT : The use of technology in teaching is often seen as a deus ex machina. Teachers and parents are quick to identify that the best way to improve teaching is the implementation of technology, by means of a Blended Learning approach. However, little thought is given to the practical considerations of this statement. Reflection on whether the Blended Learning approach can be implemented in the already established teaching practice or whether this necessitates a complete change in teaching methods rarely happens. This study aims to determine whether the incorporation of certain aspects of Blended Learning into an already existing teaching methodology results in a significant change in learners’ German performance. Grade 8 beginner German learners took part in this study during the third term of 2014. Two groups were identified: an experimental group and a control group. The experimental group did all homework assignments on the available online learning platform, Moodle, while the control group did homework assignments in the conventional way – on paper. At the end of the third term, learners’ examination results were compared to the results of the examination of the second term. The changes in the results of the two groups were compared to determine whether one group manifested a significantly greater change in results than the other. The outcome of the study is that incorporating only elements of a Blended Learning approach into an already existing teaching system, while keeping the methods of instruction constant and only changing the medium of homework delivery, does not have a significant influence on learners’ performance in German. / AFRIKAANSE OPSOMMING : Geen Afrikaanse opsomming beskikbaar nie. / rs201508

企業轉型是許多傳統企業必經的過程，往哪個方向去轉型，往往取決於企業經營者的決定，而像此篇研究所探討的A公司，所屬的產業是傳統營造與建築產業，A公司在經營的42年也因為大環境的改變，而歷經了二次轉型，經由不斷的改變商業模式，以維持企業的競爭優勢。在轉型的過程中，從原本的營造業跨足到建設業做產業價值鏈上的整合，Ａ公司在台灣的營造與建設產業上，已站穩自己的腳步。 但面臨了整體大環境不佳的情況之下，營造與建設產業市場開始緩慢的在萎縮，此時不論是向上向下整合，對於Ａ公司無法出現立即性的效益。而也在此時平台議題興起，許多傳統企業紛紛轉向平台經營。 當平台模式的出現，帶給了許多傳統產業價值鏈的破壞，例如：Uber 的出現，徹底的顛覆計程車產業原有的商業模式，但即便是運用平台的概念，與顧客接觸的渠道依然沒有改變，消費者還是跟以往的方式一樣搭程計程車。實體的銷售渠道在某些傳統產業中，還是佔了很重要的角色。這也讓傳統產業在轉型的過程中，比起從無到有的企業，來得更具有優勢。 此研究希望可以了解，傳統產業轉型平台時，是否已擁有特定的核心能耐，並與平台所需擁有的能力具有高度配適度、而這樣子的企業是否更適合去轉型成平台。除此之外，也進一步的研究，當傳統產業轉型時，該以何種方式進入平台，才可確保在新舊業務上有更好的協同效果。 / Enterprise transformation is a process that most traditional companies have to face. The type of transformation is usually decided by the person who operates the company. The traditional industry of Company A as discussed in this article is Building and Construction. Because of the changing environment, Company A has gone through Enterprise transformations 2 times by changing its business model to maintain competitive advantage in its 42 years running of business. During the transformation process, Company A has branched out its business from Building to Construction to integrate the value chain. Company A has a firm status in the Building and Construction industry. However, facing with an unsatisfactory overall business environment and the shrinking market of Building and Construction, Company A couldn’t make instant profit by neither forward nor backward integration. Meanwhile, the rise of the platforms forced enterprises to change the original business model of many traditional businesses. The presence of platform is undoubtedly a shock to traditional value chain. Take Uber for example, it has changed the business model of Taxi. Although Uber is based on the concept of the platform, it has not change the way to serve customers by providing transportation service. In some traditional industries, substantial sale channel still plays an important role and has more advantages than those virtual channels. This study aims to find whether the core competence of the traditional enterprise is correlated to the ability of running a platform, and whether such enterprise is better-off if transform to run through platform. Moreover, this study also seeks to find that by which way an enterprise use the platform when they set out to transform could create synergy in existing and new businesses.

垂直性社群平台將定位聚焦在特定主題，匯聚對特定主題有興趣的人。由於 使用者在不分眾社群平台與分眾社群平台之間，表現出多棲的行為。在Facebook崛起後的台灣社群平台市場，分眾是進入社群平台市場的機會點。然而，對平台企業而言，成功經營的關鍵挑戰是能夠以平台創造的價值建立收益流。因此本研究探討以下問題： 一、 垂直性社群平台如何獲取價值？ 二、 影響垂直性社群平台營收模式發展方向的關鍵因素為何？ 三、 驅動垂直性社群平台營收持續成長的關鍵策略為何？ 為回答上述三大問題，本研究採取多個案研究法，針對三家個案平台依序分 析其營收模式的建立、主要營收驅動力的作用過程、營收成長策略。從分析結果，本研究得到以下的結論： 一、 垂直性社群平台獲取價值的方式主要有兩種型態：其一是藉由掌握對大量 高同質性「社群成員邊」及「外部的資訊搜尋者邊」購買決策的影響力，吸引以此群人為目標客群的廠商，並與廠商在新市場進入策略或行銷或銷售等面向合作。其二是藉由對目標客群偏好需求的瞭解，推出實體商品。 二、 社群成員的特質是影響垂直性社群平台營收模式發展方向的關鍵因素。 三、 社群成員成長策略是驅動垂直性社群平台營收持續成長的關鍵。 / The position of a vertical social networking platform focuses on a specific topic, and members of the vertical social networking are interested in this specific topic. Due to multi-homing behavior of users between social networking platforms which focus on specific topics and social networking platforms which do not focus on specific topics, after the growing of Facebook in Taiwan, focusing a specific group gives platform-based companies opportunities to enter the social networking platform market. However, what the biggest challenges in running a successful platform is to establish revenue streams by the value that the platform creates. The present study tries to answer the following three questions: 1. How does a vertical social networking platform capture value？ 2. What are the key factors that affect the development direction of revenue model for a vertical social networking platform？ 3. What are the key strategies a vertical social networking platform use to drive revenue growth？ By analyzing the platform value capture mechanisms, this study concludes that: 1. Vertical social networking platforms capture value by two way mainly: first, on the basis of influence on consumer decision-making, vertical social networking platforms attract firms to cooperate on market entry strategies or marketing. Second, vertical social networking platforms could launch physical products based on understanding needs and preferences of users. 2. The common characteristic of the community members is the key factor that affects the development direction of revenue model for a vertical social networking platform. 3. The community member growth strategy is the key to drive community platform revenue growth.

The times when malware was mostly written by curious teenagers are long gone. Nowadays, threats come from criminals, competitors, and government agencies. Some of them are very skilled and very targeted in their attacks. At the same time, our devices – for instance mobile phones and TVs – have become more complex, connected, and open for the execution of third-party software. Operating systems should separate untrusted software from confidential data and critical services. But their vulnerabilities often allow malware to break the separation and isolation they are designed to provide. To strengthen protection of select assets, security research has started to create complementary machinery such as security hypervisors and separation kernels, whose sole task is separation and isolation. The reduced size of these solutions allows for thorough inspection, both manual and automated. In some cases, formal methods are applied to create mathematical proofs on the security of these systems. The actual isolation solutions themselves are carefully analyzed and included software is often even verified on binary level. The role of other software and hardware for the overall system security has received less attention so far. The subject of this thesis is to shed light on these aspects, mainly on (i) unprivileged third-party code and its ability to influence security, (ii) peripheral devices with direct access to memory, and (iii) boot code and how we can selectively enable and disable isolation services without compromising security. The papers included in this thesis are both design and verification oriented, however, with an emphasis on the analysis of instruction set architectures. With the help of a theorem prover, we implemented various types of machinery for the automated information flow analysis of several processor architectures. The analysis is guaranteed to be both sound and accurate. / Förr skrevs skadlig mjukvara mest av nyfikna tonåringar. Idag är våra datorer under ständig hot från statliga organisationer, kriminella grupper, och kanske till och med våra affärskonkurrenter. Vissa besitter stor kompetens och kan utföra fokuserade attacker. Samtidigt har tekniken runtomkring oss (såsom mobiltelefoner och tv-apparater) blivit mer komplex, uppkopplad och öppen för att exekvera mjukvara från tredje part. Operativsystem borde egentligen isolera känslig data och kritiska tjänster från mjukvara som inte är trovärdig. Men deras sårbarheter gör det oftast möjligt för skadlig mjukvara att ta sig förbi operativsystemens säkerhetsmekanismer. Detta har lett till utveckling av kompletterande verktyg vars enda funktion är att förbättra isolering av utvalda känsliga resurser. Speciella virtualiseringsmjukvaror och separationskärnor är exempel på sådana verktyg. Eftersom sådana lösningar kan utvecklas med relativt liten källkod, är det möjligt att analysera dem noggrant, både manuellt och automatiskt. I några fall används formella metoder för att generera matematiska bevis på att systemet är säkert. Själva isoleringsmjukvaran är oftast utförligt verifierad, ibland till och med på assemblernivå. Dock så har andra komponenters påverkan på systemets säkerhet hittills fått mindre uppmärksamhet, både när det gäller hårdvara och annan mjukvara. Den här avhandlingen försöker belysa dessa aspekter, huvudsakligen (i) oprivilegierad kod från tredje part och hur den kan påverka säkerheten, (ii) periferienheter med direkt tillgång till minnet och (iii) startkoden, samt hur man kan aktivera och deaktivera isolationstjänster på ett säkert sätt utan att starta om systemet. Avhandlingen är baserad på sex tidigare publikationer som handlar om både design- och verifikationsaspekter, men mest om säkerhetsanalys av instruktionsuppsättningar. Baserat på en teorembevisare har vi utvecklat olika verktyg för den automatiska informationsflödesanalysen av processorer. Vi har använt dessa verktyg för att tydliggöra vilka register oprivilegierad mjukvara har tillgång till på ARM- och MIPS-maskiner. Denna analys är garanterad att vara både korrekt och precis. Så vitt vi vet är vi de första som har publicerat en lösning för automatisk analys och bevis av informationsflödesegenskaper i standardinstruktionsuppsättningar. / <p>QC 20160919</p> / PROSPER / HASPOC

Walking outdoors requires one to deal with a wide range of visual and cognitive perturbations, i.e., multiple object tracking and making timely decisions while ignoring irrelevant information, etc. Using dual-task gait paradigm, the purpose of this thesis was to evaluate the age effects of different types of visuospatial cognitive tasks, i.e. designed cognitive game tasks and commercial computer games on gait and cognitive performances in older adults as compared to the younger adults. A standardized dual-task assessment approach, i.e. objectively evaluating both gait and cognitive performances simultaneously, has potential to be the screening tool to detect gait and cognitive impairments in early stages. Further, evaluating the training value of commercial computer games by comparing them with the designed cognitive games with objective outcome measures will help in developing multimodal dual-task intervention platform to treat and prevent age-related physical and cognitive impairments. / October 2016

As societies become increasingly connected thanks to advancing technologies and the Internet in particular, individuals and organizations (i.e. agents hereafter) engage in innumerable interaction and face constantly the possibilities thereof. Such unprecedented connectivity offers opportunities through which social and economic benefits are realised and disseminated. Nonetheless, risky and damaging interaction abound. To promote beneficial relationships and to deter adverse outcomes, agents adopt different means and resources. This thesis focuses on reputation as a crucial mechanism for promoting positive interaction, and examines the topic from game-theoretic perspective using computational methods. First, we investigate the design of reputation systems by incorporating economic incentives into algorithm design. Focusing on ubiquitous user-generated ratings on the Internet, we propose a truthful reputation mechanism that not only enforces honest reporting from individual raters but also takes into account their personal preferences. The mechanism is constructed using a blend of Bayesian Truth Serum and SimRank algorithms, both specifically adapted for our use case of online ratings. We show that the resulting mechanism is Bayesian incentive compatible and is computable in polynomial time. In addition, the mechanism is shown to be resistant to common manipulations on the Internet such as uniform fake ratings and targeted collusions. Lastly, we discuss detailed considerations for implementing the mechanism in practice. Second, we investigate experimentally the relative importance of reputational and social knowledge in sustaining cooperation in dynamic networks. In our experiments, U.S-based subjects play a repeated game where, in each round, an endogenous network is formed among a group of 13 players and each player chooses a cooperative or non-cooperative action that applies to all her connections. We vary the availability of reputational and social knowledge to subjects in 4 treatments. At the aggregate level, we find that reputational knowledge is of first-order importance for supporting cooperation, while social knowledge plays a complementary role only when reputational knowledge is available. Further community-level analysis reveals that reputational knowledge leads to the emergence of highly cooperative hubs, and a dense and cluster network, while social knowledge enhances cooperation by forming a large, dense and clustered community of cooperators who exclude outsiders through link removals and link refusals. At the individual level, reputational knowledge proves essential for the emergence of network structural characteristics that are associated with cooperative actions. In contrast, in treatments without reputational information, none of the network metrics is predicative of subjects' choices of action. Furthermore, we present UbiquityLab, a pioneering online platform for conducting real-time interactive experiments for game-theoretic studies. UbiquityLab supports both synchronous and asynchronous game models, and allows for complex and customisable interaction between subjects. It offers both back-end and front-end infrastructure with a modularised design to enable rapid development and streamlined operation. For in- stance, in synchronous mode, all per-stage and inter-stage logic are fully encapsulated by a thin server-side module, while a suite of client-side components eases the creation of game interface. The platform features a robust messaging protocol, such that player connection and game states are restored automatically upon networking errors and dropped out subjects are seamlessly substituted by customisable program players. Online experiments enjoy clear advantages over lab equivalents as they benefit from low operation cost, efficient execution, large and diverse subject pools, etc. UbiquityLab aims to promote online experiments as an emerging research methodology in experimental economics by bringing its benefits to other researchers.