In recent years, extensive studies of many interesting aspects of online community dynamics promoted a better understanding of this area. One of the most challenging problems facing builders of online communities is the design of incentive mechanisms that can ensure user participation. However, running online community experiments in the real world is expensive, and requires a great deal of motivation from users. In this thesis two major approaches are explored: system dynamics modeling and agent-based modeling, to simulate the overall behaviours of participants in online communities. Although these models are developed by using two different methodologies, both of them can provide insights into the user motivation process, incentive mechanism evaluation and community development. The target online community for my study is called Comtella, which is used in several senior Computer Science classes in the Department of Computer Science, University of Saskatchewan. Simulation models for the Comtella online community have been developed and the simulation results are useful to provide future directions for incentive mechanism improvement.

In recent years, extensive studies of many interesting aspects of online community dynamics promoted a better understanding of this area. One of the most challenging problems facing builders of online communities is the design of incentive mechanisms that can ensure user participation. However, running online community experiments in the real world is expensive, and requires a great deal of motivation from users. In this thesis two major approaches are explored: system dynamics modeling and agent-based modeling, to simulate the overall behaviours of participants in online communities. Although these models are developed by using two different methodologies, both of them can provide insights into the user motivation process, incentive mechanism evaluation and community development. The target online community for my study is called Comtella, which is used in several senior Computer Science classes in the Department of Computer Science, University of Saskatchewan. Simulation models for the Comtella online community have been developed and the simulation results are useful to provide future directions for incentive mechanism improvement.

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Abstract National Health Insurance (NHI) has been implemented in Taiwan for nearly eight years; since then, over 96% of 23 million residents of Taiwan have benefited from this program, and 70% of them are satisfied. Recently, the growth rate of healthcare expenditure, however, has been phenomenally rapid, owing to the ageing population, the economic development, the expansion of health insurance, the increased supply of healthcare resources, and the innovation of medical technology. Under the circumstance that the bill of raising the insurance premium rate could not be passed by the legislative congress, the Bureau of NHI (BNHI) was forced to economize on expense to achieve the financial balance. Currently, the BNHI implements ¡§total amount control¡¨ to control the total medical claimed payments of each medical healthcare provider. Facing the increasing volume of documentary auditing, the BNHI has to make its efforts on how to improve its auditing efficiency. This is also one of the purposes of this thesis. This study aimed to establish a reasonable and fair auditing procedure of medical claim payment, termed ¡§medical claim payments auditing (MCPA) procedure¡¨. At the stage of professional auditing, adopted the ¡§MIL-STD-105E sampling plan¡¨ to select data for professional audit and used the auditing results as a payment criterion. To verify the adaptability of the MCPA procedure, the researcher used the data provided by the institutes of Kaohsiung and Pintong as simulation objects. Further, the estimated cost model was adopted to increase the possibility of using this procedure. The MCPA procedure consists of the following characteristics: 1) The number of sampling is much lower than that of the current system used by the NHI, thus the audit labor-force and time can be reduced significantly. 2) The incentive mechanism design encourages the healthcare providers to honestly apply their medical claim payments and avoids inappropriate healthcare services. 3) Adopting international standards of sampling technology makes the MCPA procedure trustworthy and simultaneously can reduce the implementing obstructs. Keywords: National Health Insurance; Sampling plan; Incentive mechanism design

With rapid development of information technologies, especially the Internet technology, people can communicate more flexibly via various media, in which knowledge can be also shared. In gaining knowledge through the Internet, either digital content retrieval or inter-personal interaction, learning activities conducted on the Web are getting popular. This research has two main objectives. One is to develop incentive mechanisms to enhance the quantity and quality of information shared through peer-to-peer (P2P) networks. The other objective is to implement and evaluate the proposed mechanisms for inquiry-based learning on P2P networks. The pricing-like incentive mechanism is embedded on each peer to determine the price to share a document, to issue a question, and respond to a question. Through experiments, this study evaluates the effects on mitigating the free-riding problems and exchanging information through the P2P network. The results show the effectiveness of the incentive mechanisms for inquiry-based learning on P2P networks.

Peer-to-Peer (P2P) technology is a kind of decentralized framework which is applied to file sharing and video streaming in Internet predominantly. However, there are some problems, like free-riding, fairness, unexpected fluctuation, in P2P systems. Especially, without free riding controlling, many users stop contributing data and only want to receive data. To avoid these problems, a credit-based incentive mechanism using sneak, public-key cryptography and multi-source technique is proposed to make peers in system have no choice but to share data. In the proposed incentive mechanism, the concept of credit is employed. If a peer can contribute more bandwidth for sharing stream, it is arranged closer to video server, to get more credit in return, have less packet loss risk and receive better stream quality. Free-rider is a peer who denies contributing or contributes less resource than it registers to the system. In the proposed mechanism, free-riders are judged by the credits of each peer. In order to prevent illegal behaviors, the public-key cryptography is used for differentiating real and fake credit, also used for tracing credits. Experimental results show that when 90% peers are zero uploading peers, using the proposed mechanism can reduce 85% of zero uploading peers. When 90% peers are cheating peers, adopting the proposed mechanism can reduce 94% of cheating peers. System utility is usually about 100%. Maximum number of hops to video server is about five to six which is much smaller than without using the proposed mechanism, about 40 hops. The loads in managing system topology and delivering sub-streams are reduced. Besides, the resource of the system is used effectively.

Cette thèse aborde le problème de la surcharge des réseaux des données des opérateurs mobiles. La croissance des abonnements au haut débit mobile engendre aujourd'hui de nombreux goulots d'étranglement dans ces réseaux. Plus particulièrement, la disponibilité de la bande passante sur les stations de bases est de plus en plus réduite. Pour faire face à cette problématique, les opérateurs mobiles essaient de décharger le trafic des données de leurs infrastructures en déployant des réseaux de substitution à petites cellules, tels que les femtocells ou réseaux WiFi publics. Ces réseaux restent néanmoins très localisés et ne résolvent donc que très partiellement le problème. Ainsi, plus récemment, nous voyons l'émergence des réseaux opportunistes qui visent à transmettent les données en ne se basant que sur les dispositifs mobiles, c-à-d, de dispositif à dispositif. Cette thèse vise à évaluer la faisabilité de décharger le trafic de données mobile à l'aide des hotspots WiFi en étendant leur champs de couverture par l'utilisation des réseaux opportunistes. Pour ce faire, cette thèse propose un cadre pour le déchargement (offloading) de données de façon opportuniste et un mécanisme d'incitation pour encourager la coopération des utilisateurs des dispositifs mobiles. Dans une première partie de cette thèse, nous avons tracé la couverture 3G et WiFi à travers plusieurs lignes de bus à Paris afin d'évaluer la façon dont les utilisateurs et les opérateurs mobiles peuvent bénéficier des réseaux WiFi existants pour le déchargement des données. Nos résultats indiquent que les points d'accès WiFi déployés par les fournisseurs de service Internet peuvent décharger une partie non négligeable du trafic de données, cependant des restrictions telles que le temps de l'association et le processus d'authentification peuvent diminuer la quantité de données transmises. Dans une tentative d'offrir une nouvelle approche pour le déchargement mobile, nous proposons dans un second temps un cadre décisionnel multi-critères, appelé OppLite, pour décharger les données des réseaux de mobiles 3G grâce à des communications dispositif à dispositif opportunistes. Nous avons montré par des simulations qu'un tel déchargement mobile opportuniste peut étendre la couverture et l'efficacité des réseaux cellulaires, permettant un déchargement pouvant aller jusqu'à 36% des données dans certains scénarios. L'efficacité du déchargement mobile par les réseaux opportunistes dépend principalement de la tolérance au délai par l'application et de la coopération des utilisateurs mobiles. Le déchargement opportuniste dépend de la volonté de l'utilisateur d'offrir ses ressources aux autres. Nous avons donc proposé, dans un troisième temps, un mécanisme d'incitation, appelé MINEIRO, qui calcul un rang de réputation basée sur la source des messages reçus par les nœuds intermédiaires. MINEIRO permet à des réseaux composés d'un pourcentage important, allant jusqu'à 60%, de nœuds avec un comportement égoïste sans dégradation des performances dans un scénario de mobilité aléatoire. Au delà de ce pourcentage, MINEIRO permet maintenir un taux de livraison et des délais de livraison constants / This thesis addresses the overload problem of the Wireless Internet service Providers' (WISP) network. The growth of mobile broadband subscription has been leading several bottlenecks to WISPs, such as, bandwidth availability and resource sharing of over a single cellular cell. WISPs can move off data traffic from its infrastructure by deploying small cells, such as femtocells, to public WiFi networks or, more recently, to device-to-device opportunistic networks. This work evaluates the feasibility to offload mobile data traffic using WiFi hotspots, proposes a framework to opportunistic data offloading and an incentive mechanism to encourage users cooperation. We mapped 3G and WiFi coverage through several bus routes in Paris in order to evaluate how users and WISPs can benefit from the existing infrastructure. Our results indicate that the deployed WISPs access points can offload part of the data traffic, however restrictions such as association time and the authentication process may reduce the amount of offloaded data. We propose a multi-criteria decision-making framework, called OppLite, to offload data from 3G networks using opportunistic device-to-device communications. Trace-driven simulations showed that opportunistic mobile offloading can expand coverage and network efficiency, offloading up to 36% of data in certain scenarios. Thus, the effectiveness of opportunistic mobile offloading depends mainly of the delay tolerance of the applications and whether the user cooperates. Since opportunistic offloading depends on the user's willingness to offer his/her resources to others, we propose a message-based incentive mechanism that builds a reputation rank based on the source of messages received by the forwarding nodes, called MINEIRO. The network supports up to 60% of nodes with selfish behavior without performance degradation in a random mobility scenario. After this threshold, MINEIRO kept the delivery rate and the delay constant. Meanwhile, in a scenario with social-based mobility, selfish behavior degrades the network performance quickly

Nous nous proposons de modéliser différents types de mécanismes d'incitation salariale, de déterminer les conditions de leur mise en place et d'analyser leurs effets sur les efforts des salariés, la performance des firmes et le surplus collectif. Ces effets sont étudiés dans des cadres statique et dynamique. Les deux premiers chapitres (2 et 3) s'insèrent dans un cadre d'analyse statique. Dans les trois derniers chapitres (4, 5 et 6), nous intégrons une dimension temporelle dans l'analyse se passant dans un cadre dynamique. Dans le chapitre 2, nous analysons les déterminants de l'actionnariat salarié et évaluons son impact sur le bien être des différents agents économiques. Nous prouvons théoriquement et empiriquement, l'importance de considérer conjointement la désutilité à l'effort des salariés et la taille de l'entreprise pour expliquer l'actionnariat salarié. Nous montrons également que les entreprises assez larges vont distribuer à l'équilibre des parts de capital sous-optimales à leurs salariés. Nous comparons dans le chapitre 3, du point de vue des différents agents économiques, deux scénarios de partage du profit: un premier où la part de profit résulte d'une négociation et un second où cette part est fixée unilatéralement par les capitalistes. Nous montrons que les capitalistes peuvent préférer la négociation alors qu'il est possible pour les salariés de préférer une fixation unilatérale. Nous justifions également la nécessité d'une intervention de l'Etat, les intérêts des deux capitalistes et du planificateur social n'étant jamais convergents. / We aim at modeling various incentive mechanisms, determining the conditions of their implementation and analyzing their effects on employees’ efforts, the firm’s performance and the social welfare. These effects are studied in static and dynamic frameworks. The first two chapters (2 and 3) are parts of the static analysis. In the last three chapters (4, 5 and 6), we take into account a temporal dimension. In the chapter 2, we analyze the factors which determine the employee ownership implementation and estimate its impact on agents’ welfare. We prove the importance to consider jointly the effort disutility and size in the explanation of employee ownership implementation. We also show that large firms are going to distribute sub-optimal capital shares to their employees. We compare in the chapter 3, from the viewpoint of the various economic agents, two scenarios of profit sharing: the first one where the part of profit results from a negotiation and the second where this part is unilaterally fixed by capitalists. We show that those shareholders may prefer bargaining while it is possible for the employees to prefer a unilateral fixing of profit shares. We also justify the necessity of a regulator’s intervention as the interests of both capitalists and social planner never converge. The chapter 4 examines the optimal strategy of divesting actions by the large shareholder in an infinite horizon game where divesting shares allows an increase in the company’s value through its incentive effect on the managers’ efforts.

Smart devices have become one of the fundamental communication and computing devices in people's everyday lives over the past decade. Their various sensors and wireless connectivity have paved the way for a new application area called mobile crowdsensing where sensing services are provided by using the sensor outputs collected from smart devices. A mobile crowdsensing system's service quality heavily depends on the participation of smart device users who probably expect to be compensated in return for their participation. Therefore, mobile crowdsensing applications need incentive mechanisms to motivate such people into participating. In this thesis, we first defined a reverse auction based incentive mechanism for a representative mobile crowdsensing system. Then, we integrated the Vickrey-Clarke- Groves mechanism into the initial incentive mechanism so as to investigate whether truthful bidding would become the dominant strategy in the resulting incentive mechanism. We demonstrated by theoretical analysis that overbidding was the dominant strategy in the base incentive mechanism, whereas truthful bidding was the dominant strategy in the derived incentive mechanism when the VCG mechanism was applicable. Finally, we conducted simulations of both incentive mechanisms in order to measure the fairness of service prices and the fairness of cumulative participant earnings using Jain's fairness index. We observed that both the fairness of service prices and the fairness of cumulative participant earnings were generally better in the derived incentive mechanism when the VCG mechanism was applied. We also found that at least 70% of service requests had fair prices, while between 5% and 85% of participants had fair cumulative earnings in both incentive mechanisms.

市場失靈往往是政府介入干預的主要理由，一般常見的干預方法為正向的誘因激勵與負向的懲罰手段。就農地而言，因其所能提供的生態或環境的功能係屬公共財性質，具有無排他性、無敵對性、聯合消費的性質，市場上缺乏私人主動提供農地環境效益的經濟誘因，使得政府基於全民福祉之理由而介入農地保護，以提升外部效益。又為防患於未然，乃訂定管制規則予以規範違規使用行為，以降低外部成本。台灣的農地管理兼採補貼給付、賦稅減免與使用管制之政策措施，其實施經年究竟有無缺失？如何加以改進？適逢台灣主管當局刻正研擬國土計畫法（草案）且需要檢視之際，益發突顯本文研究此課題之重要性。 新古典經濟學者主張以課稅的方式消弭外部成本、以給予補貼的方式鼓勵外部效益的產生；新制度經濟學者主張透過界定財產權，經由利害關係人協商，最後達到社會整體最適生產水準，兩者各有所長，於實際適用時尚須截長補短綜合考量。本文從上述理論基礎切入，採用文獻分析法與焦點人物訪談法來檢討現行農地管理機制不足之處。基於損益均衡的補貼理念，我們意圖將正向誘因、使用市場機制引進農地管理機制中，並改進以往偏重於農地違規使用負向處罰的管理方式，以期健全農地管理，落實農業永續發展目標。 關鍵字：農地管理、誘因機制、公共財、外部性 / Market failure is often the main reason of government intervention. Generally, intervention methods always include positive incentive measures and passive punishment means. From viewpoint of farmland, it serves as biological and environmental functions with the character of public goods, which possesses features of non-exclusion, non-rival and jointly-consume. However, there is lack of economic incentives to provide environmental benefits of farmland by private market, government intervene shall be needed in farmland protection on basis of entire people welfare. Besides, the land use control regulations shall be stipulated to reduce external cost. In Taiwan, incentive programs include incentive payments, tax exemption or reduction and land use control mechanism. Do these programs manipulate efficiently? If not, how to improve them in the future? Discussion of these issues shall play an important role while the draft of National Territory Planning Act is drawn up by the Planning Authority and more examinations are necessary in Taiwan. Neoclassical economists suggest that external costs can be prevented by taxation, and external benefits shall be encouraged by offering subsidy. Neo-institutional economists argue that the problem can be solved through defining property rights, and stakeholders shall negotiate with one another to achieve optimum of social production. This article bases on exploring those theories and takes positive and negative factors into account in practice. The main research methods are literature review and focal person interview to investigate insufficiency of current incentive mechanism in farmland management. Based on concept of benefit-cost equilibrium, we intend to provide positive incentives, and include market approach into incentive mechanism of farmland management and improve passive way of punishing illegal farmland use. Through formulation of these incentive tools, farmland management mechanism shall be established soundly so as to achieve the goals of agricultural sustainable development. Keywords：Farmland Management, Incentive Mechanism, Public Goods, Externality