Abstract Due to advances of technologies and growth of Internet usage, demand for larger and larger network capacity remains the major challenge for network operators. To meet the increasing demand, optical network has become the key technology in the current and next-generation Internet. In terms of network architecture, optical packet switching (OPS) is a promising up-star in achieving high efficiency just as the electronic counterpart. However, it is currently far reached because of the difficulty in making optical random access memory and ultra-high cost in making fast optical switches that can handle more than 10^9 packets per second. Optical burst switching (OBS), on the other hand, is a more achievable, economical alternative. In OBS networks, packets are aggregated into much larger sized bursts before entering the core network. It thus does not require fast optical switches. And by incorporating one-way delayed reservation scheme, OBS avoids using optical RAM. There have been many research activities toward OBS. However, for Internet with 90% of TCP traffic, the effect of packet aggregation introduced by OBS on TCP performance is still not well understood. Detti and Listanti derived a model for it and the model was verified in simulation [2]. Yet, we found many of the assumptions in their study are not realistic. The obtained result is therefore questionable. In this thesis, we relax their assumptions and design two new models accordingly in order to get deeper understanding on the effects of packet aggregation on TCP performance. From our simulation results, we conclude three affecting factors: burst assembly, assembly delay and assembler buffer size. Burst assembly shows positive effect, while the other two demonstrate negative effects, on TCP throughput.

We present a method for detecting and correcting poor coupling in an Ocean Bottom Seismic (OBS) experiment. The basic idea of our method is that the normal component (with respect to the seafloor) of particle velocity is continuous at the water-solid interface. A comparison of the normal component of particle velocity just above and below the seafloor allows us to assess poor coupling. In other words, our method for detecting poor coupling consists of analyzing vertical particle velocities measured just above and below the seafloor. The normal component of particle velocity above the water is measured using either a vertical receiver array or a vertical source array (dipole source), whereas the normal component of particle velocity below the water is directly measured in this OBS experiment. In general, the quantities recorded in the OBS experiment are vertical and horizontal components of particle velocity, but continuity of the boundary is based on the normal component of particle velocity being oriented perpendicularly to the seafloor. For a flat seafloor, the vertical component of particle velocity values just above and below the seafloor must be almost equal according to the continuity condition at the water-solid boundary. However, for a dipping seafloor this is not the case. We have established that we can differentiate a poor coupling effect from a dipping-seafloor effect by using the vertical component of particle velocity. We have tested our method on real (Eugene Island) data and synthetic (finite-difference) data. For finite-difference synthetics, we have used a grid spacing 0.25 meters to properly simulate the water-solid interface. By examining the uniformity (with respect to offset) of cross-correlation between the vertical component of particle velocity just above and below the seafloor, we were able to detect poor coupling and to differentiate it with any dipping effect at the seafloor. The energy of data just above and below the seafloor were also used for detecting poor coupling and for differentiating it from dipping-seafloor effect.

Nowadays, the hospital managers are facing increasing financial difficulties, because of the global budget policy from the national health institute. Patient-oriented services, good manner of the care providers, and the rapid response of the hospital to the medical environment are among the important factors for hospital survival. Therefore, many medical care providers had designed the clinical pathway for standardized medical treatment to control the medical costs, but they also allowed some extra-services for attracting and recruiting more patients. In this study, by way of participating management and job enrichment, we try to improve the quality and the patient satisfaction of the pelvic sonography provided by Obs/Gyn department. The study was proceeded in 2 ways. First, we designed a standardized obstetrical and gynecological sonography service pathway, which include a standard flow chart, customer encounter, and a checklist. Second, we measured the total service time duration, including those of pre-service consultation, actual sonography performing, and the post-service consultation. The measurements were performed before and after the application of the standardized sonography pathway. The measurement results were used to analyze and evaluate the validity and efficiency of the originally designed pathway. The study results demonstrate that after application of the sonography pathway, the total service time duration is reduced in Gyn sonography, but increased in Obs sonography. For Gyn sonography, the duration of pre-service consultation and post-service consultation were significantly reduced after application of standardized pathway. Further analysis revealed that thorough pre-service consultation not only made our patients more comfortable, but also reduced the post-service consultation time. However, the actual sonography performing time was increased, because of the adding of the standardized conversation. For obstetrical sonography, the duration of the actual sonography performing time was decreased, possibly due to the adding of standardized conversation, which answered most of the questions that the pregnant patients want to know about. In conclusion, by way of establishment and repeated reassessment/correction of the standardized sonography pathway, the quality of the sonography services can be greatly improved, and the patient¡¦s satisfaction can be even greater. The same experience can be applied to other fields. The quality of medical care can be more stable by the application of standardized clinical pathway. Besides, through the efforts of quality control, the medical cost can be limited, and the financial burden of the hospital and medical care providers can be reduced, making a double-win medical environment. Key Word: service pathways,total service, Obs/Gyn sonography

Cycling in Germany- and also in many countries in Europe and all over the world-has become more relevant in recent years especially due to the corona pandemic. People have been afraid using public transport and tend to use individual means of transport more intensive. Many cities across Europe supported cycling and pop-up cycle lanes were marked on streets with yellow lines in order to give cyclists more space for safe and comfortable riding. Cities like Brussels, Vienna or Berlin implemented these kinds of ''unconventional' infrastructure in 2020 during tbe first Corona lockdowns. Though, evaluations have shown that the use of these pop-up lanes led to increasing numbers of users on these tracks, these tracks were marked only on a marginal share of the streets in contrast to the whole cycling network of a city. Other indicators depicting that cycling is advancing are the numbers of sales and the increased willingness to pay for a new bicycle. In Germany, the average price over all sold bicycles in 2021 was about €1,400 EUR. Compared to 2019 (€929 per bike) this is an increase ofabout 50%. This increase of sales numbers of e-bikes explains this increase. In 2021 about two million e-bikes were sold in Germany in contrast to 2. 7 million conventional bikes. The overall market value of sold bicycles in Germany was 6.56 billion euros which is an increase by 60% in comparison to 2011. Nevertheless, a recent Germany-wide survey with over 11,000 participants shows that 91 % of tbe cyclists feel unsafe in Gennan traffic. 69% state that the keeping too little distance between other traffic participants is one of the reasons that people feel unsafe in traffic. The survey also reveals that the feeling of safety would increase by building more bicycle infrastructure (81%) and a clear separation between motorized and nonmotorized traffic (62%). [from Introduction]

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

This thesis presents a wide tuning, low phase noise CMOS integer-N frequency synthesizer with 1.8V power supply. The frequency synthesizer is designed using the TSMC 0.18£gm CMOS 1P6M technology. The proposed frequency synthesizer consists of a phase-frequency detector, a charge pump, a low-pass loop filter, a voltage control oscillator, an auto-band selection (ABS), an optimum-band selection (OBS), and a pulse-swallow divider. In system design, we present the new architecture for voltage-controlled oscillator with switched capacitors technique with a lowered VCO gain (KVCO) to achieve wide tuning range and low phase noise in order to cover the desired operating frequency bands and to accommodate process, voltage, and temperature (PVT) variations. The ABS accomplishes the efficient search for a VCO discrete tuning curve among a group of frequency sub-bands. It is apparent to reduce the calibration time by adopting the binary search algorithm to select the calibration word. However, the variation of Kvco across different channels can still be large after the execution of ABS. There might be many sub-bands covering the desired frequency. Hence the sub-band which is selected by ABS could not be an optimum choice for the minimum Kvco variation. The OBS is proposed to implement an algorithm in order to find the optimum solution which has the minimum Kvco variation and covers the desired frequency. The Kvco variation is quantified by OBS and using this value to adjust the charge pump current. Therefore, Loop bandwidth and stability were maintained across the operating range by using optimum-band selection(OBS) and a programmable charge pump.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-03-20T22:19:55Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_PredicaoFalhasRedes.pdf: 2224854 bytes, checksum: b43ccaab6ffbeb4bd1e246c5fa8a2d2e (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-04-02T12:31:14Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_PredicaoFalhasRedes.pdf: 2224854 bytes, checksum: b43ccaab6ffbeb4bd1e246c5fa8a2d2e (MD5) / Made available in DSpace on 2013-04-02T12:31:14Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_PredicaoFalhasRedes.pdf: 2224854 bytes, checksum: b43ccaab6ffbeb4bd1e246c5fa8a2d2e (MD5) Previous issue date: 2013 / Este trabalho apresenta uma proposta para predição de falhas em rede de grade OBS com plano de controle GMPLS que auxilia as aplicações em ambientes de colaboração, como exemplo a E-Science. Os agentes de monitoração de tráfego, denominado DQMA-Fuzzy, verificam parâmetros relacionados à QoS e às imperfeições nos enlaces ópticos. Por apresentar uma solução mais rápida e facilmente implementável, foi desenvolvido um sistema baseado em lógica Fuzzy para dar mais robustez às decisões dos agentes. Simulações no NS-2 (Network Simulator – 2) demonstram que a proposta minimiza bloqueios na rede e balanceia o uso dos recursos da grade, garantindo níveis de serviços bem definidos, auxiliando na engenharia de tráfego e na predição de falhas. / This paper presents a proposal for predict failures in OBS grid network with GMPLS to assist applications in collaborative environments, like E-Science. Agents monitoring traffic (DQMA-Fuzzy) for related QoS parameters and others related to imperfections in optical links. A system based on fuzzy logic has been developed to give more robustness and flexibility in decision-making agents, because it presents a solution faster and easily implementable. NS-2 (Network Simulator – 2) simulations show that the proposed DQMA-Fuzzy is able to minimize blockages and balancing the use of grid resources, ensuring well-defined service levels, assisting in traffic engineering and fault prediction.

The popularization of Internet has turned the telecom world upside down over the last two decades. Network operators, vendors and service providers are being challenged to adapt themselves to Internet requirements in a way to properly serve the huge number of demanding users (residential and business). The Internet (data-oriented network) is supported by an IP packet-switched architecture on top of a circuit-switched, optical-based architecture (voice-oriented network), which results in a complex and rather costly infrastructure to the transport of IP traffic (the dominant traffic nowadays). In such a way, a simple and IP-adapted network architecture is desired. From the transport network perspective, both Generalized Multi-Protocol Label Switching (GMPLS) and Optical Burst Switching (OBS) technologies are part of the set of solutions to progress towards an IP-over-WDM architecture, providing intelligence in the control and management of resources (i.e. GMPLS) as well as a good network resource access and usage (i.e. OBS). The GMPLS framework is the key enabler to orchestrate a unified optical network control and thus reduce network operational expenses (OPEX), while increasing operator's revenues. Simultaneously, the OBS technology is one of the well positioned switching technologies to realize the envisioned IP-over-WDM network architecture, leveraging on the statistical multiplexing of data plane resources to enable sub-wavelength in optical networks. Despite of the GMPLS principle of unified control, little effort has been put on extending it to incorporate the OBS technology and many open questions still remain. From the IP network perspective, the Internet is facing scalability issues as enormous quantities of service instances and devices must be managed. Nowadays, it is believed that the current Internet features and mechanisms cannot cope with the size and dynamics of the Future Internet. Compact Routing is one of the main breakthrough paradigms on the design of a routing system scalable with the Future Internet requirements. It intends to address the fundamental limits of current stretch-1 shortest-path routing in terms of RT scalability (aiming at sub-linear growth). Although "static" compact routing works fine, scaling logarithmically on the number of nodes even in scale-free graphs such as Internet, it does not handle dynamic graphs. Moreover, as multimedia content/services proliferate, the multicast is again under the spotlight as bandwidth efficiency and low RT sizes are desired. However, it makes the problem even worse as more routing entries should be maintained. In a nutshell, the main objective of this thesis in to contribute with fully detailed solutions dealing both with i) GMPLS-OBS control interoperability (Part I), fostering unified control over multiple switching domains and reduce redundancy in IP transport. The proposed solution overcomes every interoperability technology-specific issue as well as it offers (absolute) QoS guarantees overcoming OBS performance issues by making use of the GMPLS traffic-engineering (TE) features. Keys extensions to the GMPLS protocol standards are equally approached; and ii) new compact routing scheme for multicast scenarios, in order to overcome the Future Internet inter-domain routing system scalability problem (Part II). In such a way, the first known name-independent (i.e. topology unaware) compact multicast routing algorithm is proposed. On the other hand, the AnyTraffic Labeled concept is also introduced saving on forwarding entries by sharing a single forwarding entry to unicast and multicast traffic type. Exhaustive simulation campaigns are run in both cases in order to assess the reliability and feasible of the proposals.

Transport Control Protocol (TCP) is the dominant protocol in modern communication networks, in which the issues of reliability, flow, and congestion control must be handled efficiently. This thesis studies the impact of the next-generation bufferless optical burst-switched (OBS) networks on the performance of TCP congestion-control implementations (i.e., dropping-based, explicit-notification-based, and delay-based). The burst contention phenomenon caused by the buffer-less nature of OBS occurs randomly and has a negative impact on dropping-based TCP since it causes a false indication of network congestion that leads to improper reaction on a burst drop event. In this thesis we study the impact of these random burst losses on dropping-based TCP throughput. We introduce a novel congestion control scheme for TCP over OBS networks, called Statistical Additive Increase Multiplicative Decrease (SAIMD). SAIMD maintains and analyzes a number of previous round trip times (RTTs) at the TCP senders in order to identify the confidence with which a packet-loss event is due to network congestion. The confidence is derived by positioning short-term RTT in the spectrum of long-term historical RTTs. The derived confidence corresponding to the packet loss is then taken in to account by the policy developed for TCP congestion-window adjustment. For explicit-notification TCP, we propose a new TCP implementation over OBS networks, called TCP with Explicit Burst Loss Contention Notification (TCP-BCL). We examine the throughput performance of a number of representative TCP implementations over OBS networks, and analyze the TCP performance degradation due to the misinterpretation of timeout and packet-loss events. We also demonstrate that the proposed TCP-BCL scheme can counter the negative effect of OBS burst losses and is superior to conventional TCP architectures in OBS networks. For delay-based TCP, we observe that this type of TCP implementation cannot detect network congestion when deployed over typical OBS networks since RTT fluctuations are minor. Also, delay-based TCP can suffer from falsely detecting network congestion when the underlying OBS network provides burst retransmission and/or deflection. Due to the fact that burst retransmission and deflection schemes introduce additional delays for bursts that are retransmitted or deflected, TCP cannot determine whether this sudden delay is due to network congestion or simply to burst recovery at the OBS layer. In this thesis we study the behaviour of delay-based TCP Vegas over OBS networks, and propose a version of threshold-based TCP Vegas that is suitable for the characteristics of OBS networks. The threshold-based TCP Vegas is able to distinguish increases in packet delay due to network congestion from burst contention at low traffic loads. The evolution of OBS technology is highly coupled with its ability to support upper-layer applications. Without fully understanding the burst transmission behaviour and the associated impact on the TCP congestion-control mechanism, it will be difficult to exploit the advantages of OBS networks fully.

Transport Control Protocol (TCP) is the dominant protocol in modern communication networks, in which the issues of reliability, flow, and congestion control must be handled efficiently. This thesis studies the impact of the next-generation bufferless optical burst-switched (OBS) networks on the performance of TCP congestion-control implementations (i.e., dropping-based, explicit-notification-based, and delay-based). The burst contention phenomenon caused by the buffer-less nature of OBS occurs randomly and has a negative impact on dropping-based TCP since it causes a false indication of network congestion that leads to improper reaction on a burst drop event. In this thesis we study the impact of these random burst losses on dropping-based TCP throughput. We introduce a novel congestion control scheme for TCP over OBS networks, called Statistical Additive Increase Multiplicative Decrease (SAIMD). SAIMD maintains and analyzes a number of previous round trip times (RTTs) at the TCP senders in order to identify the confidence with which a packet-loss event is due to network congestion. The confidence is derived by positioning short-term RTT in the spectrum of long-term historical RTTs. The derived confidence corresponding to the packet loss is then taken in to account by the policy developed for TCP congestion-window adjustment. For explicit-notification TCP, we propose a new TCP implementation over OBS networks, called TCP with Explicit Burst Loss Contention Notification (TCP-BCL). We examine the throughput performance of a number of representative TCP implementations over OBS networks, and analyze the TCP performance degradation due to the misinterpretation of timeout and packet-loss events. We also demonstrate that the proposed TCP-BCL scheme can counter the negative effect of OBS burst losses and is superior to conventional TCP architectures in OBS networks. For delay-based TCP, we observe that this type of TCP implementation cannot detect network congestion when deployed over typical OBS networks since RTT fluctuations are minor. Also, delay-based TCP can suffer from falsely detecting network congestion when the underlying OBS network provides burst retransmission and/or deflection. Due to the fact that burst retransmission and deflection schemes introduce additional delays for bursts that are retransmitted or deflected, TCP cannot determine whether this sudden delay is due to network congestion or simply to burst recovery at the OBS layer. In this thesis we study the behaviour of delay-based TCP Vegas over OBS networks, and propose a version of threshold-based TCP Vegas that is suitable for the characteristics of OBS networks. The threshold-based TCP Vegas is able to distinguish increases in packet delay due to network congestion from burst contention at low traffic loads. The evolution of OBS technology is highly coupled with its ability to support upper-layer applications. Without fully understanding the burst transmission behaviour and the associated impact on the TCP congestion-control mechanism, it will be difficult to exploit the advantages of OBS networks fully.