Every day data communication networks carry more and more information, which sometimes is very important and needs to be delivered in time. To achieve that, data transfer networks must meet quality requirements that are formed in SLA contracts between clients and service providers. Supplied data transfer link’s quality is described by worldwide defined quality metrics, which include: one way delay, IP delay variation, link loss and round trip time. In order to measure these metrics, special software was created during projects “QoS monitoring system” first phase. This paper continues the project and explores available tuning methods for created software including time synchronization and mobility problems in order to provide better accuracy with higher mobility. New system topology and time offset correction using measurement packets were proposed during the analysis part. Possible system improvements were put to test in order to evaluate the efficiency during the experiment.

The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications. The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications. In response to the above challenges, this thesis addresses the dependence of WAMC applications on the underlying ICT systems. Specifically, two of the WAMC system data quality attributes, latency and completeness, are examined together with their effects on a typical WAMC application, PMU-based wide-area damping systems. The outcomes of this research include quantified results in the form of PMU communication delays and data frame losses, and probability distributions that can model the PMU communication delays. Moreover, design requirements are determined for the wide-area damping systems, and three different delay-robust designs for this WAMC application are validated based on the above results. Finally, a virtual PMU is developed to perform power system and communication network co-simulations. The results reported by this thesis offer a prospect for better predictions of the performance of the supporting ICT systems in terms of PMU data latency and completeness. These results can be further used to design and optimize the WAMC applications and their underlying ICT systems in an integrated manner. This thesis also contributes a systematic approach to design the wide-area damping system considering the PMU data latency and completeness. Finally, the developed virtual PMU, as part of a co-simulation platform, provides a means to investigate the dependence of WAMC applications on the capabilities of the underlying ICT systems in a cost-efficient manner. / <p>QC 20131015</p>

Paskutiniu metu duomenų centrai teikia skirtingas tinklo, informacijos talpinimo, terminalinių serverių ir kitas paslaugas. Paslaugų kokybė priklauso ne tik nuo specifikuojamų SLA parametrų, bet ir nuo vartotojo poreikių. Taigi buvo sudaryta duomenų centrų paslaugų įvertinimo metodika, skirta palyginti paslaugų kokybę tiek vartotojams, tiek ir paslaugų teikėjams. Siūloma taikyti serverių bei tinklo sujungimų rezervacijas, norint užtikrinti aukštą paslaugų pateikiamumą. Dvi populiariausios duomenų centrų paslaugos buvo ištirtos: „thin-client“ (terminalinių serverių) architektūra, ir Web paslaugos. Web paslaugos kokybės įvertinimo bandymai buvo atlikti, norint parodyti, kad WRT kokybės parametras yra labiau informatyvus nei įprasti duomenų perdavimo tinklo parametrai. „Thin-client“ architektūros analizė parodė, kad ji gali būti naudojama LAN ir WAN tinkluose, ir gali būti labai ekonomiškai naudinga. Tinklo ir serverių resursų stebėjimas turi būti vykdomas, norint teikti aukštos kokybės paslaugas - taigi duomenų centrų paslaugų teikėjai privalo naudoti reikiamą aparatūrinę ir programinę įrangą periodiškiems matavimams atlikti, bei saugoti ir apdoroti gautus rezultatus. / Nowadays datacenters provide different network, hosting, terminal desktop and other services, and it has become very important to be able to evaluate the quality of these services. SLA (Service Level Agreement) metrics define the quality of service, but it also depends on the needs of the particular user. So the evaluation methodology was created in order to compare the quality of services, both: for the user, and for the datacenter service provider. A service provider has to implement the server architecture with network connection and server redundancy in order to assure high service availability. Two most popular datacenter services were analyzed: “thin-client” architecture and web services. The web service quality evaluation experiments have been made to show that web oriented performance metric "Web Response Time" (WRT) is more informative for web service quality assurance, comparing to the traditional latency and loss metrics in the network environment. “Thin-client” architecture analysis show that it can be used both in LAN and WAN networks, and it can be economically useful to outsource IT systems to datacenters by using this technology. Network and server resource performance monitoring has to be done in order to supply high quality services - so datacenter service providers have to use monitoring hardware and software to make periodical measurements and collect, store and process the results.

A limited set of Processing Element (PE) pairs in a parallel computer cover the internal communications of scalable parallel programs. We take advantage of this property using the concept of Sparse Flat Neighborhood Networks (Sparse FNNs). Sparse FNNs are network designs that provide single-switch latency and full wire bandwidth for each specified PE pair, despite using relatively few network interfaces per PE and switches that have far fewer ports than there are PEs. This dissertation discusses the design problem, runtime support, and working prototype (KASY0) for Sparse FNNs. KASY0 not only demonstrated the claimed properties, but also set world records for its price/performance and performance on a specific application. Parallel supercomputers execute many portions of an application simultaneously. For scalable programs, the more PEs the system has, the greater the potential speedup. Portions executing on different PEs may be able to work independently for short periods, but the performance desired might not be achieved due to delays in communication between PEs. The set of PE pairs that will communicate often is both predictable and small relative to the number of possible PE pairings. This sparseness property can be exploited in the design and implementation of networks for massively parallel supercomputers. The sparseness of communicating pairs is rooted in the fact that each of the human-designed communication patterns commonly used in parallel programs has the property that the number of communicating pairs grows relatively slowly as the number of PEs is increased. Additionally, the number of pairs in the union of all communication patterns used in a suite of parallel programs grows surprisingly slowly due to pair synergy: the same pair often appears in multiple communication patterns. Detailed analysis of communication patterns clearly shows that the number of PE pairs actually communicating is very sparse, although the structure of the sparseness can be complex.

An open queueing network model (QNM) is proposed for wormhole-routed hypercubes with finite buffers and deterministic routing subject to a compound Poisson arrival process (CPP) with geometrically distributed batches or, equivalently, a generalised exponential (GE) interarrival time distribution. The GE/G/1/K queue and appropriate GE-type flow formulae are adopted, as cost-effective building blocks, in a queue-by-queue decomposition of the entire network. Consequently, analytic expressions for the channel holding time, buffering delay, contention blocking and mean message latency are determined. The validity of the analytic approximations is demonstrated against results obtained through simulation experiments. Moreover, it is shown that the wormholerouted hypercubes suffer progressive performance degradation with increasing traffic variability (burstiness).

A relationship between overweight and excessive daytime sleepiness (EDS) has been suggested in the adult population, and to a limited extent in the pediatric population. Daytime sleepiness can interfere with various components of daytime function. In light of the increase in the rates of pediatric overweight and obesity, the aim of this study was to investigate the relationship between weight and EDS in a pediatric population. Using a retrospective approach, data collected in a pediatric sleep clinic was analyzed. Objective measures of EDS were correlated with age, gender, body mass index percentile, and overnight sleep test recording variables. In males and in all children under the age of 13 years old, EDS was more common in those weighing above the normal range, EDS was present particularly during mid-morning hours. Additionally, weight above the normal range correlated with evidence of EDS after adjusting for measures of sleep pathologies.

A relationship between overweight and excessive daytime sleepiness (EDS) has been suggested in the adult population, and to a limited extent in the pediatric population. Daytime sleepiness can interfere with various components of daytime function. In light of the increase in the rates of pediatric overweight and obesity, the aim of this study was to investigate the relationship between weight and EDS in a pediatric population. Using a retrospective approach, data collected in a pediatric sleep clinic was analyzed. Objective measures of EDS were correlated with age, gender, body mass index percentile, and overnight sleep test recording variables. In males and in all children under the age of 13 years old, EDS was more common in those weighing above the normal range, EDS was present particularly during mid-morning hours. Additionally, weight above the normal range correlated with evidence of EDS after adjusting for measures of sleep pathologies.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-150).

Thesis (Ph. D.)--University of Oklahoma. / Includes bibliographical references.