Next generation data centres are expected to support both advance resource reservation and on-demand access, but the system performance for such a computing environment has not been well-investigated. A reservation request is characterized by a start time, duration, and resource requirement. Discrete event simulation is used to study the performance characteristics of reservation systems. The basic strategy is to accept a request if resources are available and reject the request otherwise. The performance metrics considered are resource utilization and blocking probability. Results showing the impact of input parameters on these performance metrics are presented. It is found that the resource utilization is quite low. Two strategies that can be used to improve the performance for advance reservation are evaluated. The first strategy allows the start time to be delayed up to some maximum value, while the second allows the possibility of non-uniform resource allocation over the duration of the reservation. Simulation results showing the performance improvements of these two strategies are presented. Resources not used by advance reservation are used to support on-demand access. The performance metrics of interest is the mean response time. Simulation results showing the impact of resource availability and its variation over time on the mean response time are presented. These results provide valuable insights into the performance of systems with time-varying processing capacity. They can also be used to develop guidelines for the non-uniform resource allocation strategy for advance reservation in case the reserved resources are used for interactive access.

Next generation data centres are expected to support both advance resource reservation and on-demand access, but the system performance for such a computing environment has not been well-investigated. A reservation request is characterized by a start time, duration, and resource requirement. Discrete event simulation is used to study the performance characteristics of reservation systems. The basic strategy is to accept a request if resources are available and reject the request otherwise. The performance metrics considered are resource utilization and blocking probability. Results showing the impact of input parameters on these performance metrics are presented. It is found that the resource utilization is quite low. Two strategies that can be used to improve the performance for advance reservation are evaluated. The first strategy allows the start time to be delayed up to some maximum value, while the second allows the possibility of non-uniform resource allocation over the duration of the reservation. Simulation results showing the performance improvements of these two strategies are presented. Resources not used by advance reservation are used to support on-demand access. The performance metrics of interest is the mean response time. Simulation results showing the impact of resource availability and its variation over time on the mean response time are presented. These results provide valuable insights into the performance of systems with time-varying processing capacity. They can also be used to develop guidelines for the non-uniform resource allocation strategy for advance reservation in case the reserved resources are used for interactive access.

This thesis considers the use of the tone reservation (TR) technique in orthogonal frequency division multiplexing (OFDM) systems. The nonlinear distortion is usually introduces by the high power amplifiers (HPA) used in wireless communications systems. It orders to reduce the inter-modulation distortion (IMD) in OFDM systems. In addition to the original peak-to-average power ratio (PAPR)-reduction criterion, we propose signal-to-distortion plus noise power ratio (SDNR) criterion and distortion power plus inverse of signal power (DIS) criterion. Based on these criteria, the cross-entropy (CE) algorithm is introduced to determine desired values of the peak reduction carriers (PRCs) to improve the bit error rate (BER) of nonlinearly distorted. Computational complexity is always the major concern of PAPR technique. Therefore, the real-valued PRCs and the modified transform decomposition (MTD) method are introduced here to dramatically decrease complexity of inverse fast Fourier transform (IFFT) operation with slightly performance loss. The simulation results show that the proposed criteria provide a better BER performance and a lower computational complexity.

No description available.

No description available.

Tyrimo objektas – Kamšos botaninio – zoologinio draustinio teritorijoje sutinkami medžiojamieji žvėrys (graužikai, kiškiažvėriai, plėšrieji, porakanopiniai) ir paukščiai (antiniai, vištiniai, tilvikiniai, varniniai). Darbo tikslas – įvertinti Kamšos botaninio – zoologinio draustinio medžiojamosios faunos būklę. Siekiant darbo tikslo buvo iškelti tokie uždaviniai: 1) nustatyti draustinio medžiojamosios faunos rūšinę sudėtį, atskirų rūšių gausą bei tankį; 2) nustatyti plėšrūnų ir aukų santykį bei jo atitikimą ekologiniam santykiui; 3) įvertinti elninių žvėrių žiemos ganyklų būklę; 4) nustatyti draustinio teritorijoje perinčių, galinčių perėti bei sutinkamų tik migracijų metu medžiojamųjų paukš����������ių rūšinę sudėtį. Tyrimo metodai – Lietuvos ir užsienio autorių mokslinės literatūros analizė bei sintezė, duomenų grupavimas, statistiniai metodai, grafinis vaizdavimas, Ch. Aldous'o metodas, Pojarkovo metodas, R. McCain'o metodas. Tyrimo laikotarpis apima 2005 -2007 metus. Išstudijavus lietuvių ir užsienio autorių mokslinius veikalus bei periodinę literatūrą apie medžiojamosios faunos elgseną įtakojančius veiksnius, elninių žvėrių gausa, tankis žiemos ganyklose, bendras tankis, pasiskirstymas teritorijoje žiemą nustatyta žiemos ekskrementų krūvelių apskaitos metodu, R. McCain'o metodu. Elninių žvėrių žiemos ganyklų būklė įvertinta Ch. Aldous'o metodu. Bebrų šeimos vidutinio dydžio koeficientas nustatytas pagal medžių ir krūmų graužimų kiekį Pojarkovo metodu. / Object of research – hunted animals (gnawers, hare-type animals, predators, double-hoofed animals) and wildfowl (duck-type, gallinaceous, scolopacidae (sandpiper-type), crow-type) met in the territory of wadding botanical – zoological reservation. Purpose of the Paper – evaluate the state of hunted fauna in the wadding botanical – zoological reservation. Achieving the purpose the following goals were raised: 1) to determine the varietal composition, abundance and density of certain species of the hunted fauna in the reservation; 2) to determine the ratio between predators and preys, and its conformity with ecological ratio; 3) to evaluate the state of winter pastures of cervine animals; 4) to determine the varietal composition of brooding, able to brood and only in the time of migration met wildfowl. Methods of research – analysis and synthesis of Lithuanian and foreign scientific literature, data grouping, statistical methods, graphical presentation, Ch. Aldous method, Pojarkov method, R. McCain method. The research period is the years 2005 – 2007. After studying scientific works of Lithuanian and foreign authors and periodic literature about the factors influencing the behaviour of hunted fauna, the abundance of cervine animals, density in winter pastures, general density, distribution in the territory in winter were determined by the method of winter-time excrement heaps record, R. McCain method. The state of winter pastures of cervine animals was determined by the Ch... [to full text]

In the final master’s dissertation analysis on current 15below communication platform PASNGR. In addition to this there is a short analysis done on each of PASNGR components to find out usage possibilities. Furthermore, the platform is dependant on Reservation Systems, so analysis on them is done as well, including processes and data. The goal of this dissertation is to create a mobile app integrated into PASNGR. For this reason integration analysis is done, by reviewing components, data and functions. After analysis is done, Business Process Model is created to represent the workflow of the app, including internal processes and interaction with PASNGR. Furthermore a review of mobile application technologies is done, including common tools used in development. By doing this there is the best solution for current 15below developers’ environment found. The solution would mean the least resources to be used to develop the app. Finally a prototype of the mobile application is created, to show the possibilities. The app works on Android and iOS platforms, gives an ability for user to download itineraries and store for offline usage, an ability to scan a barcode at the airport straight from the app, give post flight experience feedback for the airline, receive schedule change notifications and accept them. / Baigiamajame magistro darbe atliekama kompanijos „15below“ naudojamos avialinijų komunikacijos su keleiviais platformos „PASNGR“ analizė. Atskirai atliekama trumpa kiekvieno „PASNGR“ modulio apžvalga įvertinant taikymo galimybes. Be to, kadangi platforma yra priklausoma nuo globaliųjų paskirstymo sistemų, apžvelgiamos ir jos apimant procesus, bei naudojamus duomenis. Darbe yra numatomas sukurti mobiliosios aplikacijos prototipas surištas su „PASNGR“ platforma. Tam tikslui yra atliekama integracijos analizė, apžvelgiant komponentus, duomenis ir funkcijas. Galiausiai yra sukuriamas veiklos proceso modelis atvaizduojantis mobiliosios aplikacijos prototipo veikimo principus, bei interakciją su platforma „PASNGR“. Darbo eigoje apžvelgiamos mobiliųjų aplikacijų technologijos, bei įrankiai joms kurti. Taip parenkamas priimtiniausias spendimas esamai kompanijos „15below“ programuotojų aplinkai ir lemiantis minimalias sąnaudas. Galiausiai sukuriamas mobiliosios aplikacijos prototipas veikiantis Android ir iOS platformose, gebantis atsisiųsti elektroninius bilietus į mobilųjį įrenginį ir jame išsaugoti naudojimui neprisijungus prie interneto, leidžiantis naudotojui skenuoti brūkšninį kodą oro uoste, po skrydžio pateikti nuomonę apie gautas avialinijų paslaugas, priimti pranešimus apie skrydžių pakeitimus, bei leisti juos patvirtinti.

Ultra-wideband (UWB) technologies with higher data rates and lower transmission power over shorter ranges, have enabled a new set of applications in Wireless Personal Area Networks (WPANs). For example, UWB can offer data rates 50 to 500 times higher than the current WPAN technologies such as Bluetooth. This property makes UWB a primary candidate for indoor high-speed multimedia applications such as whole-house Internet Protocol Television (IPTV) and Personal Video Recorder (PVR). Lower power emission brings less interference to other devices, and larger bandwidth makes UWB less affected by interference from others, which are very attractive attributes in a household environment. However, the effective and efficient utilization of such high data rate wireless channel represents a new challenge to WPAN Media Access Control (MAC), especially for high quality video streaming applications. To meet the minimum bandwidth and maximum delay requirement for Quality-of-Service (QoS) guarantee, high-definition IPTV and PVR services usually need to reserve a certain amount of channel time for exclusive access in a dynamic manner, since the number of video flows may change over time in a piconet. WiMedia Alliances MAC protocols for UWB-based WPANs have become an international standard. The Distributed Reservation Protocol (DRP) is part of this standard that reserves the wireless channel on a slot-by-slot basis for different flows. However, not much work has been done on DRP reservation algorithms and their performance. In this research, we propose, analyze and evaluate two application-aware reservation algorithms. One algorithm allocates time slots based on the first-fit idea whereas the other takes one step further by doing a best-fit reservation according to the maximum tolerable delay bound. Our proposed algorithms try to find the best possible time slots for any requests with respect to the existing reservations in the piconet and those arriving later. With these algorithms, devices in the same piconet that have data to transmit can negotiate and reserve time slots based on their traffic specification and QoS requirement while following WiMedia MAC reservation policies. We analyze the reservation algorithms and policies with a tiered overflow model, and evaluate their performance with Network Simulator (NS-2 ) and an MPEG-4 video traffic generator. We further discuss the ways of improving video streaming quality and system resource utilization in UWB networks.

Low-cost carriers and escalading fuel costs are placing increased pressure on US legacy carriers to reposition traditional revenue management techniques towards more customer-centric approaches. In this context, recent critiques of revenue management models question the validity of assumptions used to describe passenger cancellation and no-show behavior. Since forecasts of cancellation and no-shows are used to determine overbooking levels, i.e, authorization levels in excess of capacity, concerns related to possible missed revenue opportunities are justifiable. The goal of this research is to explore the impact of time-to-event forecasts of cancellations on airlines' revenue streams. To determine the intensity of the cancellation process, a discrete time proportional odds (DTPO) model with a prospective time scale was estimated for a sample of tickets provided by the Airline Reporting Corporation. Empirical results based on 2004 data from eight domestic US markets indicate that the intensity of the cancellation process is strongly influenced both by the time from ticket purchase and the time before flight departure, as well as several other covariates, including departure day of week, market, and group size. In order to assess potential revenue benefits associated with the DTPO formulation, a modified simulation experiment of a "single-resource capacity control" was designed. Simulation results indicate that time-to-event cancellation forecasts can generate revenue gains up to 2%. Overall, this research provides new insights into the transitional properties associated with the cancellation process, which will help airlines to improve their overbooking strategies.

Typescript. Includes vita and abstract. Includes bibliographical references (leaves 391-413). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.