La résilience apparente du secteur financier haïtien face à la crise financière de 2007-2008 soulève de nombreuses questions quant à son degré réel d’immunité face au risque systémique et aux raisons fondamentales qui auraient pu expliquer ce phénomène. Leur apporter des éclairages, notamment à partir d’études empiriques, peut aider à mieux cerner les enjeux et la formulation d’une politique macro-prudentielle pour Haïti. De fait, Haïti est un pays à faible revenu disposant d'un système financier formel restreint. De ce point de vue, son exposition aux aléas de l’environnement financier international peut paraître relativement faible. Toutefois, on se demande comment protéger l’industrie bancaire – et, incidemment l’économie haïtienne – d’un risque de nature systémique, compte tenu en particulier de l’ampleur des transferts de liquidité par la diaspora et ceux en nature. On peut donc y voir une source supplémentaire de vulnérabilité en cas de récession appelant un changement de priorité chez ces pays donateurs aux dépens de l’équilibre financier global de cette petite économie de la zone Caraïbe. Dans cette perspective, le présent travail de thèse vise d’abord à déterminer les principaux facteurs de la résilience des banques haïtiennes à la crise financière de 2007-2008. Les interdépendances entre les cycles financiers haïtien et ceux de ses voisins nord-américains sont ainsi étudiées. Pour apprécier la dimension systémique du risque que fait peser l’activité des banques, l’analyse porte aussi sur les liens entre cycle de crédit et cycle d’activité en Haïti. Ensuite, des estimations sont réalisées pour quantifier l’impact de la variabilité de la conjoncture sur les performances des banques. Les enseignements tirés de ces analyses alimentent la réflexion sur l’élaboration d’un dispositif de surveillance macro-prudentielle en Haïti. Les résultats obtenus attestent du lien étroit entre le cycle financier haïtien et ceux des membres de l’accord de libre échange nord-américain. Ceci représente une source de risques exogènes pour le système financier haïtien. De plus, l’analyse de l’impact de la variabilité de l’environnement macroéconomique sur les performances financières des banques commerciales haïtiennes supportent l’hypothèse de la fragilité du secteur bancaire. La diversité des expériences de politique macroprudentielle invite à recommander une voie médiane, entre séparation totale et fusion complète des pouvoirs monétaires et de surveillance de l’industrie bancaire, compatible avec les contraintes auxquelles Haïti est soumise. Finalement, l’implémentation d’une direction de macroprudence et une liste de plusieurs recommandations d’ordre macroprudentiel ont été proposées. Ces propositions visent à répondre aux problématiques qui semblent mettre en lumière les limites des instruments de la politique monétaire. / The apparent resilience of the financial sector in Haiti towards the financial crisis of 2007-2008 raises many questions about the actual degree of resistance to systemic risk and the fundamental reasons that could explain this phenomenon. Providing insights, especially from empirical studies can help better understand the issues and the need for a strong macro -prudential policy in Haiti. In fact, Haiti is a low-income country with a limited formal financial system. From this point of view, its exposure to the unpredictable international financial environment may seem relatively low. However, one wonders how to protect the banking industry - and incidentally the Haitian economy – from a systemic risk, especially given the magnitude of the transfers of food and money from the Diaspora. It can therefore be seen as an additional source of vulnerability to recession resulting to a change of emphasis in the donor countries at the expense of overall financial equilibrium of this small economy in the Caribbean. The purpose of this thesis is to first identify the key factors of the resilience of Haitian banks to the financial crisis of 2007-2008. It also covers the interdependencies between Haitian financial cycles and those of its North American neighbors. To assess the systemic dimension of risk posed by the activities of banks, the analysis also focuses on the relationship between the credit cycle and the business cycle in Haiti. Second, estimates are made to quantify the impact of change in economic environment on the performance of banks. The lessons learned from these analyses feed the thought on the development of an efficient setup for macro-prudential regulation in Haiti. The results demonstrate the close relationship between the Haitian financial cycle and those members of the Agreement North American Free Trade Agreement. This is an exogenous source of risk for the Haitian financial system. In addition, the analysis of the impact of a change in the macroeconomic environment on the financial performance of the Haitian commercial banks strengthens the hypothesis of the banking system’s fragile state. The diversity of macro-prudential policy experiments lead me to recommend a compromise between total separation and complete fusion of monetary authorities and monitoring of the banking industry, consistent with the constraints that Haiti is facing. Finally, the implementation of a macro-prudential department as well as a list of several macro-prudential recommendations has been suggested. These proposals aim to address the issues that highlight the limits of the effectiveness of the monetary policy instruments.

Wireless communication systems utilize the wireless medium to perform over-the-air (OTA) data transfer. There are many factors that can impact the quality of wireless communications, such as medium imperfection, interfering environment, mismatch of transceivers, etc. To mitigate these problems and improve the quality of service (QoS), this research study is conducted on three important topics including synchronization techniques, impairment estimation theory and techniques, and interference alignment techniques. In this thesis, it firstly present a dual link algorithm to align and manage the interference of multiple-input and multiple-output (MIMO) networks. A field-programmable gate array (FPGA) prototype is designed for software defined radio (SDR) platforms. As one of the key components, a hardware efficient architecture is proposed for the implementation of singular value decomposition (SVD). Secondly, it proposes a maximum-likelihood (ML) based synchronization approach for carrier frequency synchronization for MIMO systems. The algorithm is also implemented on FPGA for real-time performance evaluation. Finally, as an exemplary study of machine learning techniques for wireless communications, a neural network (NN) based estimator is proposed to perform coarse frequency offset estimations for MIMO systems. The proposed NN based estimator can accommodate various channel models and the results show promising performance in terms of accuracy and estimation range. In summary, this thesis provides a comprehensive study on interference alignment, carrier synchronization, and impairment estimation using different approaches. Efficient hardware implementations for the key algorithms are also presented.

The thesis examines the ability to have synchronized playout of audio from multiple devices. The paths between the source of this audio and the output devices may be different. Our objective is to provide a generic low-cost solution, without the use of special hardware. The context of this work is internet telephony, but the work is also applicable to other settings. In internet telephony this synchronization not only contributes to the natural flow of conversation, but also maintains the spatial effect of the incoming audio streams, as well as the location awareness of the peers. We envisioned users of handheld devices might collectively utilize their personal devices to enable a shared spatial audio environment. In the simplest case two users each with monophonic terminals could provide stereo. Hence, the second part of this study addresses the practical issue of how such synchronization could be utilized in a internet telephony client to provide such multidevice playout. We utilized minisip, as an open-source Session Initiation Protocol (SIP) client supporting security, as the basic client. To realize the vision, we ported minisip to a Pocket PC environment. In the second part of this thesis we examine the process of porting preexisting code to such a new architecture, as well as how to map an existing human-computer interface to such a handheld device. The thesis shows that synchronization is possible and explores some of the implementation’s limitations. A clear result is the need to combine the results of several theses into the common trunk code - so as to combine the earlier RTCP work with this synchronization work and to provide the a human-computer interface which is suitable for many different handheld devices, ranging from Pocket PCs to SmartPhones. / Rapporten visar på möjligheten att synkronisera ljuduppspelning på multipla ljudenheter. Vägarna från ljudkllan till de olika högtalarna (utenheterna) kan skilja sig. Vårt mål är att tillhandahålla en generell lösning till en lågt kostnad, utan att behöva använda specialhårdvara. Området för detta arbete är internettelefoni, men arbetet är även tillämpbart inom andra områden. I fallet med internettelefoni så bidrar ljudsynkroniseringen inte enbart till det naturliga konversationsflödet, utan även till de rumsrelaterade aspekterna av de inkommande ljudströmmarna och samtalsparternas medvetenhet om sina geografiska positioner. Vi förutser att användare av mobila terminaler kan komma att använda sina terminaler tillsammans för att möjliggöra en gemensam ljudmiljö. I sitt enklaste utförande kan två monoenheter tillsammans skapa en ljudmiljö för stereo-ljud. Därför adresserar den andra delen av studien hur denna typ av ljudsynkronisering kan användas inom IP-telefoni för att möjliggöra synkroniserad uppspelning på flera enheter. Vi använde minisip, en klient för SIP byggd på öppen källkod och med säkerhetsstöd, som en grundläggande terminal. För att realisera vår vision så portade vi minisip till Pocket PC-miljön. I den andra delen av den här rapporten undersöker vi även processen för att portera existerande kod till en sådan arktitektur, och hur man överför existerande användargränssnitt till en handhållen terminal. Denna rapport visar att synkronisering är möjlig men visar samtidigt på en del av begränsningarna i implementationen. Ett tydligt resultat är behovet av att kombinera tidigare rapporters resultat – för att kombinera tidigare arbete inom RTCP med detta arbete inom synkronisering och för att tillhandahålla ett användargränssnitt lämpat för många olika handhållna terminaler, från Pocket PC-baserade till SmartPhone-baserade system.

The Voice over IP (VoIP) technology has become prevalent today due to its lower cost than traditional telephony and its ability to support new value-added services. Additionally, the increasing availability of wireless internet access has led to research studies examining the combination of wireless network access with voice over IP. With the widespread availability of advanced mobile phones and Pocket PCs, the need for VoIP applications on these mobile platforms is tangible. To enable this, we need to evaluate the current wireless access technologies to see if they can support the necessary traffic and implement software to offer these VoIP services to users. In order to easily implement an IP-based service on GSM technology, we should use the GPRS service provided by the GSM operators. In this thesis, we evaluate Voice over IP service over GPRS in terms of feasibility and quality. Following this we ported a locally developed VoIP program to a Pocket PC (with GSM SIM-card support) which runs Microsoft’s Windows Mobile in order to provide suitable software as needed to offer the service from such a portable device. / VoIP tekniken har blivit en rådande teknik numera på grund av dess lägre kostnader och mervärdestjänster som erbjuds jämfört med traditional telefoni. Samtidigt som tendensen mot mer tillgänglig trådlöst internet har underlättat och därmed driver mera studier inom dessa områden. Den allt mer utbredda användningen av avancerade mobiltelefoner och handdatorer numera har lett till ökat behov av att använda VoIP tekniken för dessa mobila utrustningar är alltmer kännbar. För att möjliggöra användadet av VoIP tekniken så behöver vi först och främst utvärdera dagens existerande teknologier för att stödja iden och för det andra måste vi kunna implementera en mjukvara vilket kan erbjuda olika typer av tjänster för slutanvändaren. För att kunna använda en IP-baserad tjänst på GSM teknologin så måste vi använda oss utan GPRS tjänster som tillhandahålls av GSM opratörer. I detta examens arbete kommer vi att utvärdera VoIP tjänster på GPRS när det gäller kvalitet och möjligheter. Därefter kommer vi att Portning en VoIP mjukvara till en handdator (utrustad med GSM sim-kort) vilket har windows Mobile operativsystemet som erbjuder en rad olika tjänster.

Honey bees utilize their circadian rhythms to accurately predict the time of day. This ability allows foragers to remember the specific timing of food availability and its location for several days. Previous studies have provided strong evidence toward light/dark cycles being the primary Zeitgeber for honey bees. Work in our laboratory described large individual variation in the endogenous period length of honey bee foragers from the same colony and differences in the endogenous rhythms under different constant temperatures. In this study, we further this work by examining the temperature inside the honey bee colony. By placing temperature and light data loggers at different locations inside the colony we measured temperature at various locations within the colony. We observed significant oscillations of the temperature inside the hive, that show seasonal patterns. We then simulated the observed temperature oscillations in the laboratory and found that using the temperature cycle as a Zeitgeber, foragers present large individual differences in the phase of locomotor rhythms for temperature. Moreover, foragers successfully synchronize their locomotor rhythms to these simulated temperature cycles. Advancing the cycle by six hours, resulting in changes in the phase of activity in some foragers in the assay. The results are shown in this study highlight the importance of temperature as a potential Zeitgeber in the field. Future studies will examine the possible functional and evolutionary role of the observed phase differences of circadian rhythms.

The Bluetooth wireless transmission standard provides a low-power data link between electronic devices over relatively short ranges. These links, also known as piconets, transmit using frequency hopping spread spectrum (FHSS) to send information over the air. As more applications for Bluetooth technology become available, the number of Bluetooth devices will continue to increase. With this increase in use, there will be a decrease in performance that can be attributed to Bluetooth "inter-piconet" interference. To date, very little has been published on the subject of inter-piconet interference. Previous studies have derived mean packet error rates for an increase in the number of piconets present. To come up with the mean rate, many papers make the assumption that the probability of a Bluetooth device hopping to a channel is random. However, making this assumption does not explain what happens in real time. This research gives some insight into what really happens when multiple piconets are interfering in real time. Bluetooth devices actually use a frequency hopping algorithm to determine the hopping sequence. This algorithm has been implemented in software to test various aspects of inter-piconet interference. Previous studies have shown that synchronizing the clocks among neighboring piconets will result in an increase in performance. This study shows that there are cases where synchronization alone will not provide sufficient improvement. Experimental testing has been conducted to validate some of the simulated results. Adjacent channel interference was observed during experimentation. This contradicts previous research, which has assumed that adjacent channel interference is insignificant. / Master of Science

Recent increases in hard fault rates in modern chip multi-processors have led to a variety of approaches to try and save manufacturing yield. Among these are: fine-grain fault tolerance (such as error correction coding, redundant cache lines, and redundant functional units), and large-grain fault tolerance (such as disabling of faulty cores, adding extra cores, and core salvaging techniques). This paper considers the case of core salvaging techniques and the heterogeneous per- formance introduced when these techniques have some salvaged and some non-faulty cores. It proposes a hypervisor-based hardware thread scheduler, triggered by detection of spin locks and thread imbalance, that mitigates the loss of throughput resulting from this het- erogeneity. Specifically, a new algorithm, called Most ProgressMade algorithm, reduces the number of synchronization locks held on a salvaged core and balances the time each thread in an application spends running on that core. For some benchmarks, the results show as much as a 2.68x increase in performance over a salvaged chip multi-processor without this technique.

One consequence of the increasing number of small satellite missions is an increasing demand for high data rate downlinks. As the satellites transmit at high data rates, ground-side receivers need to demodulate the transmitted data as quickly as possible. While application specific hardware can be designed, software defined radio solutions for ground stations are attractive for their flexibility, adaptability, and portability. Another industry trend is the increasing use of Graphics Processing Units (GPUs) in general-purpose processing. By performing many operations simultaneously, GPUs are capable of accelerating processing when given a problem that can be implemented in a parallel manner. Furthermore, once a parallel algorithm is implemented, further speedups are possible by increasing hardware resources without need for any revision in the algorithm. This project combines the above ideas by implementing a software defined radio algorithm to quickly demodulate high-speed data on a GPU. It demonstrates the viability of the GPU in software defined radio applications and particularly in the area of fast demodulation.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18040号 / 理博第3918号 / 新制||理||1566(附属図書館) / 30898 / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 國府 寛司, 教授 加藤 毅, 准教授 浅岡 正幸 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18991号 / 工博第4033号 / 新制||工||1621(附属図書館) / 31942 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 土居 伸二, 教授 小林 哲生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM