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State-of-the-art onboard spacecraft avionics use SpaceWire networks to interconnect payload data-handling sub-systems. This includes high data-rate sensors and instruments, processing units, and memory devices. SpaceWire is an interconnection network composed of nodes and routers connected by bi-directional, point-to-point, high-speed, serial-data communication links. SpaceWire is established as one of the main data-handling protocols and is being used on many ESA, NASA and JAXA spacecraft. SpaceWire is very successful for being fast, flexible and simple to use and implement. However it does not implement Quality of Service mechanisms, which aim to provide guarantees in terms of reliability and timely delivery to data generated by network clients. Quality of Service is increasingly being deployed in commercial ground technologies and its availability for space applications, which requires high reliability and performance, is of high interest for the space community. This thesis researches how Quality of Service can be provided to existing SpaceWire networks. Existing solutions for ground-based technologies cannot be directly used because of the constraints imposed by the limitations of space-qualified electronics. Due to these limitations SpaceWire uses wormhole routing which has many benefits but makes it more challenging to obtain timing guarantees and to achieve a deterministic behaviour. These challenges are addressed in this work with a careful analysis of existing Quality of Service techniques and the implementation of a novel set of protocols specifically designed for SpaceWire networks. These new protocols target specific use cases and utilise different mechanisms to achieve the required reliability, timely delivery and determinism. Traditional and novel techniques are deployed for first time in SpaceWire networks. In particular, segmentation, acknowledgements, retry, time-division multiplexing an cross-layer techniques are considered, analysed, implemented and evaluated with extensive prototyping efforts. SpaceWire provides high-rate data transfers but the next generation of payload instruments are going to require multi-gigabit capabilities. SpaceFibre is a new onboard networking technology under development which aims to satisfy these new requirements, keeping compatibility with SpaceWire user-applications. As a new standard, SpaceFibre offers the opportunity to implement Quality of Service techniques without the limitations imposed by the SpaceWire standard. The last part of this thesis focuses on the specification of the SpaceFibre standard in order to provide the Quality of Service required by next generation of space applications. This work includes analytical studies, software simulations, and hardware prototyping of new concepts which are the basis of the Quality of Service mechanisms defined in the new SpaceFibre standard. Therefore, a critical contribution is made to the definition and evaluation of a novel Quality of Service solution which provides high reliability, bandwidth reservation, priority and deterministic delivery to SpaceFibre links.

The main aim of my master thesis was to get acquainted with the implementation of quality-of-service support methods in UMTS 3G mobile network and the evaluation of these methods in a simulation environment with main interest in the characteristic features of the traffic classes. The impact of the QoS methods available on different service types were verified in the OPNET Modeler simulation environment. I examined mainly the potentials of the model to support the required quality parameters for the connections. The models of typical network applications, available in real UMTS networks, together with two examples of mobile networks, operating voice and video services in combination with standard data services, were defined in this simulation environment. My work also contains the detailed description of configuration parameters fundamental for correct behavior of the simulation models. The simulation also shows the case, when the transport service is rejected due to the lack of network resources. The key parameters of the model are also described and their effect on the service quality with and without QoS control are compared in separate scenarios. Finally, I investigated the effect of mobility of the end stations on the communication process, especially on the duration of a file transmission.

Student Number : 9812990V - MSc project report - School of Electrical Engineering - Faculty of Engineering and the Built Environment / The NGN is a multi-service network which inter-works with the Public Switched Telephone Network (PSTN), the voice network and the data network provided by Internet. Through network independent APIs such as OSA-Parlay, the NGN slowly migrates and converges Telecoms and IT networks, voice and Internet, into a common packet infrastructure. The OSA/Parlay group defines a softswitch architecture which provides network independent APIs or SCFs that enable cross network application development The Parlay softswitch provides connectivity to underlying transport networks for application providers. The standard specifies the interaction between application providers and the softswitch. However, the standard does not specify an interface to regulate the interaction between service providers and the consumer/end user domain. This means that applications housed in the service provider domain have no defined interfaces to manage service delivery to the consumer domain. For most service providers, the lack of a non-standardized API set impedes efforts to decrease application creation and deployment time. This research investigates the design and implementation of a standard consumer interface which can be used by application providers within an OSA/Parlay system to deliver service content to end users. The main objectives with regard to the functionality provided by the interface include the integration of facilities which will assist application providers to manage end user access and authentication (to enable users to establish a secure context for service usage), subscription (to handle the subscription life cycle), and service usage management (to enable the initiation and termination of services). The TINA-Consortium (TINA-C) has developed a service architecture to support the creation and provisioning of services in the NGN. The TINA architecture offers a comprehensive set of concepts and principles that can be used in the design of NGN services. The architecture consists of a set of reusable and interoperable service components encapsulating a rich and well defined set of APIs aimed at supporting the interaction between application providers and consumers. TINA’s session concepts, information structures, interfaces and service components can be used to support the design of a consumer premises end user interface for OSA/Parlay. This research also aims to explore the feasibility of using the TINA API within an OSA/Parlay system to support consumer domain service delivery. In order to implement the consumer interface for Parlay applications, the ability of the TINA service architecture to provide Access and Authentication management; Subscription and Profile management; and Service Usage management was investigated. The report documents the design and implementation of an OSA/Parlay consumer interface utilizing TINA service components and interfaces.

In the distribution network of a large retailer, shipments can either be transported by the retailer's own trucks or outsourced to third-party logistics (3PL) companies. In the former case, shipments are consolidated and transported from their origins through an intermediate facility, namely a crossdock. At a crossdock, shipments are unloaded, sorted, re-consolidated, loaded and transported to their destinations. The consolidation process offers economies of scale that reduce the transportation costs. At the same time, it increases travel distances and incurs handling costs at a crossdock. For this reason, consolidation is uneconomic for a shipment in which origin and destination are located close to one other, especially through a distant crossdock. It is cheaper to outsource transportation of such a shipment to 3PL companies. This shipping decision raises a series of questions. Should a shipment be consolidated through a crossdock or outsourced to 3PL companies? How do facility locations, the operational cost of a crossdock and mode of shipments influence the shipping decision? Can the robustness and potential growth of a crossdock be measured? How does outsourcing affect the robustness and potential growth of a crossdock? We formulate a strategic model of a retailer's distribution network as an economic trade-off between consolidated shipments through a crossdock and outsourced shipments to 3PL companies. We study the locus of facility locations where the costs of a consolidated shipment and an outsourced shipment are equal and discover that the trade-off can be modeled by classical geometric curves, particularly an ellipse, a hyperbola, a limacon and a Cartesian oval. These curves can be developed into a preliminary routing and locating tool. We also observe interesting connections between the single hub crossdocking network and other fields of geometric study, such as Voronoi diagrams and geometric inversion. In addition, the area bounded by these curves represents the likelihood in which a particular shipment is consolidated through a crossdock. We expand this concept to multiple vendor-store pairs and suggest an index that measures robustness and potential growth of a particular crossdock. This asymptotic-probability index explains economic driving factors of consolidation and outsourcing. Although the derivation of the index is limited by the dimension and spatial distribution of facilities, its numerical value can be determined by a computer simulation. Therefore, we use Monte Carlo simulation to compute the proposed index to explain the outsourcing and the interaction between TL threshold0.1 and mode of shipments. The analysis and computer simulation suggest that outsourcing may cause an adverse effect in a single hub crossdocking network, resulting in the abrupt reduction of consolidated shipments in the network. Furthermore, we propose transportation planning to alleviate this effect and compare them to the optimal allocation. The routing and locating application of the model is illustrated using the Home Depot distribution network. Our model predicts 5.5% and additional 1.0% savings in transportation cost by re-allocation of shipments and re-location of crossdocks, respectively. The empirical study shows that the adverse effect of outsourcing can be eliminated by limiting the number of crossdocks used by each store.

本研究主要是欲從1980年代福利國家危機所發展出來的因應對策“福利多元化”的理念出發，依此理念所發展出來的「少年福利多元化」的政策主張，來探討我國少年福利在福利多元化政策上的施行現況、成效與困境。因此，對於目前建構少年福利服務網絡的少年福利各相關服務組織，包括政府單位、及民間社會福利機構，在服務網絡上如何進行協調聯繫，及服務項目整合的情形，即瞭解目前少年服務機構的服務提供、與少年服務網絡聯繫建構現況，並藉由探討歸納少年服務網絡建構的影響因素，以尋求最佳少年服務網絡模式的建立。 因此，本研究的研究架構，主要有3個概念即：少年福利各相關服務組織特性—組織進行協調聯繫，與服務整合現況—建構最佳少年服務網絡。而在研究方法的採取上，則主要是採質化的研究方法，並以文獻探討法，及質的訪談法2者相輔。文獻探討的部分主要是包括：整體少年福利施行現況，及高雄市少年福利相關文獻資料的蒐集。而質的訪談法部分，則是兼採開放式與封閉式的訪談型式來深入探討蒐集資料。另外，在訪談對象的選取，則是先採立意取樣的方式，選取資料最多、經驗最豐富的青少年福利服務中心，作為基礎，再由訪談的青少年福利服務中心，以滾雪球的方式確定有少年業務聯繫關係的民間社會福利機構對象。最後再針對這些民間社會福利機構，進行約談訪問。 本研究的研究發現則主要有以下幾點： 1.資源不足，服務提供有限：不論是針對一般青少年的休閒娛樂服務方面，亦或是不幸少年的寄養、與安置服務上，各少年服務機構皆無法完全配合少年的服務需求來提供服務。 2.人力不足，經費編列有限：不論是政府單位、青少年福利服務中心，亦或是民間社會福利機構，皆是普遍會存在的服務機構問題，且受訪的機構服務工作者皆反應機構目前在人力上有呈現不足、缺乏的困境，多數機構的社工員必須身兼數職，工作負擔很重。 3.資源尋求，促進服務聯繫：研究發現：促進服務機構進行少年服務協調聯繫的主要動機，不論是在政府單位，亦或是民間社會福利機構彼此間，促進其進行服務聯繫的動機，不外乎以資源相互尋求、與相互支援為主。 4.個案整合，機構合作無間：在高雄市少年服務網絡的建構中，主管機關社會局在建立少年服務資源網絡上，除與其所屬的青少年福利服務中心相互聯繫外，在少年服務的提供上亦多以公辦民營、協助補助、個案委託、方案委託等方式，交由民間機構來辦理少年福利服務，尤其在公設民營、與委託業務上更是蓬勃。另外，在機構所進行服務整合的項目，則是以少年個案整合為主。 5.本位主義，網絡建構難題：不論是青少年福利服務中心，亦或是民間社會福利機構的工作者皆反應，在機構間的協調聯繫成效方面，皆有遇到與教育機構、單位溝通協調困難的問題，而主要的原因則是專業機構本位主義所致。 6.定位不明，認知未達共識：服務機構工作者反應政府社政單位在與民間社會福利機構，進行委辦、承辦、協辦等不同業務時，經常由於彼此間對相互的角色、定位的認知不同，而產生協調上的問題。 7.網絡建構，默契須再培養：雖然目前整個少年服務網絡在建構上，各專業服務機構彼此間在聯繫的動機、及整合情形，皆有助於整個少年服務網絡體系的建構與維繫，但彼此間在少年服務工作的團隊默契上，仍須再培養。 8.資源競爭，機構相互排擠：少年福利的民間資源不足，使得少年在老人、婦女、兒童等弱勢族群中，又是更為弱勢的一群。且機構工作者表示：在資源缺乏下，同性質的服務機構彼此間會相互競爭資源、相互排擠，如此使得小型、新成立的服務機構，難以生存的現象。 最後在研究限制方面，則有2部分，即：研究方法的限制，與研究時間、人力的限制。研究方法的限制，則是包括：文獻研究法、與質的訪談法等2種資料蒐集方法的缺點，也就是在研究方法上的限制。而在研究時間、與人力的限制方面，則為研究範圍上的限制、及訪談對象數量上的限制等此2部分，為本研究的研究方面的限制。

The dissertation investigates the form of network governance in the context of U.S. homeless service networks (namely continuum of care programs; CoCs). This research examines CoC homeless service networks by applying the institutional collective action (ICA) perspectives to understand the forms of network governance as a reflection of network context. The ICA perspective has been applied to understand the rational behavior of network members for the network governance form to mitigate the collective action problems. The ICA perspective helps understand why network members accept specific governance structures with their expectation to maximize the benefits and minimize the costs and uncertainty in their process of collaboration. This dissertation uses the data of CoC networks and point in time data from the U.S. Department of Housing and Urban Development in 2019 and Census. The data developed for this study offers the homeless incidences, geographical characteristics, and governance structure based on the contact information. For an in-depth understanding, interview by CoC leaders was integrated. This dissertation consists of four essays about 1) Literature review on network governance and the theoretical argument in the ICA framework, 2) Background and network governance of the U.S. homeless service networks, 3) Factors affecting the choice of network administrative organization (NAO) form, and 4) Interviews by the representatives of CoC networks. The findings inform us of the governance structure for the effective service provisions and coordination of actions of network members and about why and how network organizations choose a form of network governance.

This dissertation examines the factors and combinations of factors that affect the performance of continuum of care homeless service networks, applying the configurational approach of contingency theory to data sets drawn from federal sources. The study accepts the two key assumptions from the theory: (1) that there are multiple paths to high performance and (2) key conditions have a joint influence on network performance. The data analysis in this study has two parts. The first employs OLS regression to examine the causal relationship between independent variables and the performance of permanent supportive housing (PSH) programs. This study also applies fuzzy set qualitative comparative analysis (fsQCA) to identify multiple combinations of factors that influence the performance of PSH programs. The results identify key factors and multiple combinations of factors that lead to high and low network performance. Federal CoC funding emerges as a core condition for high and low performance, but all relevant conditions can be critical factors depending on how they interact with other relevant conditions. This analysis helps expand the utility of existing contingency theory by using it to explain the dynamic interactions between factors in the context of public service networks. Ultimately, this dissertation confirms that fsQCA can be a useful method for evaluating the performance of public service networks and helping them provide more services more effectively.

Cette thèse se place dans le cadre de services web en dépassant leur description pour considérer leur structuration en réseaux (réseaux d'interaction et réseaux de similitude). Nous proposons des méthodes basées sur les motifs, la modélisation probabiliste et l'analyse des concepts formels, pour améliorer la qualité des services découverts. Trois contributions sont alors proposées: découverte de services diversifiés, recommandation de services et cohérence des communautés de services détectées. Nous structurons d'abord les services sous forme de réseaux. Afin de diversifier les résultats de la découverte, nous proposons une méthode probabiliste qui se base à la fois sur la pertinence, la diversité et la densité des services. Dans le cas de requêtes complexes, nous exploitons le réseau d'interaction de services construit et la notion de diversité dans les graphes pour identifier les services web qui sont susceptibles d'être composables. Nous proposons également un système de recommandation hybride basé sur le contenu et le filtrage collaboratif. L'originalité de la méthode proposée vient de la combinaison des modèles thématiques et les motifs fréquents pour capturer la sémantique commune maximale d'un ensemble de services. Enfin, au lieu de ne traiter que des services individuels, nous considérons aussi un ensemble de services regroupés sous forme de communautés de services pour la recommandation. Nous proposons dans ce contexte, une méthode qui combine la sémantique et la topologie dans les réseaux afin d'évaluer la qualité et la cohérence sémantique des communautés détectées, et classer également les algorithmes de détection de communautés. / As a part of this thesis, we exceed the description of web services to consider their structure as networks (i.e. similarity and interaction web service networks). We propose methods based on patterns, topic models and formal concept analysis, to improve the quality of discovered services. Three contributions are then proposed: (1) diversified services discovery, (2) services recommendation and (3) consistency of detected communities. Firstly, we propose modeling the space of web services through networks. To discover the diversified services corresponding to a given query, we propose a probabilistic method to diversify the discovery results based on relevancy, diversity and service density. In case of complex requests, it is necessary to combine multiple web services to fulfill this kind of requests. In this regard, we use the interaction web service network and the diversity notion in graphs to identify all possible services compositions. We also propose a new hybrid recommendation system based on both content and collaborative filtering. Its originality comes from the combination of probabilistic topic models and pattern mining to capture the maximal common semantic of a set of services. Finally, instead of processing individual services, we consider a set of services grouped into service communities for the recommendation. We propose in this context, a new method combining both topology and semantics to evaluate the quality and the semantic consistency of detected communities, and also rank the detection communities algorithms.

Scalable and accurate analysis of networks is essential to a wide variety of existing and emerging network systems. Specifically, network measurement and analysis helps to understand networks, improve existing services, and enable new data-mining applications. To support various services and applications in large-scale networks, network analytics must address the following challenges: (i) how to conduct scalable analysis in networks with a large number of nodes and links, (ii) how to flexibly accommodate various objectives from different administrative tasks, (iii) and how to cope with the dynamic changes in the networks. This dissertation presents novel path analysis schemes that effectively address the above challenges in analyzing pair-wise relationships among networked entities. In doing so, we make the following three major contributions to large-scale IP networks, social networks, and application service networks. For IP networks, we propose an accurate and flexible framework for path property monitoring. Analyzing the performance side of paths between pairs of nodes, our framework incorporates approaches that perform exact reconstruction of path properties as well as approximate reconstruction. Our framework is highly scalable to design measurement experiments that span thousands of routers and end hosts. It is also flexible to accommodate a variety of design requirements. For social networks, we present scalable and accurate graph embedding schemes. Aimed at analyzing the pair-wise relationships of social network users, we present three dimensionality reduction schemes leveraging matrix factorization, count-min sketch, and graph clustering paired with spectral graph embedding. As concrete applications showing the practical value of our schemes, we apply them to the important social analysis tasks of proximity estimation, missing link inference, and link prediction. The results clearly demonstrate the accuracy, scalability, and flexibility of our schemes for analyzing social networks with millions of nodes and tens of millions of links. For application service networks, we provide a proactive service quality assessment scheme. Analyzing the relationship between the satisfaction level of subscribers of an IPTV service and network performance indicators, our proposed scheme proactively (i.e., detect issues before IPTV subscribers complain) assesses user-perceived service quality using performance metrics collected from the network. From our evaluation using network data collected from a commercial IPTV service provider, we show that our scheme is able to predict 60% of the service problems that are complained by customers with only 0.1% of false positives. / text