Abstract Information and communications technology (ICT) companies face challenges in an unpredictable business environment, where demand-supply forecasting is not accurate enough. How to optimally manage product change process and demand-supply chain in this type of environment? Companies face pressures to simultaneously be efficient, responsive and innovative, i.e. to minimise costs, and shorten order delivery and product change periods. This thesis included three action research cycles within a real demand-supply chain of a significant international actor. Each action research cycle sought answers by going into one extreme of minimising costs, diminishing order delivery period, or shortening product change periods. In practice, these research cycles included the case company changing their business accordingly for each of these cases. Conducting required changes in the case company were economically significant trials. The results of this doctoral dissertation provide tips for global high tech companies. Large international companies typically have manufacturing sites in different parts of the world. According to the results, mental shift from local optimisation to a global one is required for efficient manufacturing operations. Companies have traditionally considered their strategy as a choice between minimising costs, quick delivery, and rapid product change. Also, companies have believed that one single strategy is adequate and applicable to all of their products. According to this thesis, different products may have a different strategy. This would allow companies to flexibly react to the needs of different customer groups, business environments, and different competitors. In addition, strategy can be changed relatively often, monthly, weekly, or even daily. Based on the results of this doctoral thesis, companies must harmonise their product portfolio globally, including all their sites. Once the same product version is at all sites, they can help each other from components supply viewpoint. Consequently, product changes can be taken through quicker. / Tiivistelmä Informaatio- ja kommunikaatioalan yritykset kohtaavat haasteita toimiessaan vaikeasti ennustettavassa liiketoimintaympäristössä, jossa tilaus-toimitusennusteet ovat epätarkkoja. Miten tällaisessa ympäristössä hallitaan optimaalisesti tuotemuutosprosessi ja tilaus-toimitusketju? Yrityksillä on paineita olla samanaikaisesti tehokkaita ja innovatiivisia: miten minimoida sekä kustannuksia että lyhentää toimitus- ja tuotemuutosaikoja. Tämä väitöskirja tehtiin toimintatutkimuksena merkittävän kansainvälisen yrityksen todellisessa tilaus-toimitusketjussa. Toimintatutkimus eteni vaiheittain kokeilemalla kolmea eri ääripäätä minimoimalla 1) kustannuksia, 2) toimitusaikoja ja 3) tuotemuutosaikoja. Käytännössä nämä ääripäät sisälsivät case-yrityksen liiketoiminnan muuttamista vastaavasti sisältäen taloudellisesti merkittäviä kokeiluja. Tämän väitöskirjan tulokset tarjoavat käytännön esimerkkejä globaaleille korkeanteknologian yrityksille. Suurilla kansainvälisillä yrityksillä on tyypillisesti valmistusyksiköitä eripuolilla maailmaa. Tämän tutkimuksen tulosten mukaan yritykset tarvitsevat asennemuutoksen paikallisesta optimoinnista globaaliin, jotta tuotanto toimisi tehokkaasti. Perinteisesti yritykset ovat ymmärtäneet strategian tarkoittavan valinnan tekemistä kustannusten minimoinnin, nopeiden toimitusaikojen tai nopeiden tuotemuutosten välillä. Yritykset ovat myös uskoneet, että yksi yrityskohtainen strategia kattaa kaikki yrityksen tuotteet. Tämän väitöskirjan tulosten mukaan yrityksen eri tuotteilla voi olla erilainen strategia. Tällainen ratkaisu mahdollistaa nopean reagoinnin muutoksiin asiakasryhmien tarpeissa, liiketoimintaympäristössä ja kilpailutilanteissa. Strategiaa voidaan myös muuttaa usein, kuukausittain, viikoittain tai jopa päivittäin. Tämän väitöskirjatutkimuksen tulosten mukaan, yritysten tulisi harmonisoida tuoteportfolionsa globaalisti kattaen kaikki tuotantolaitokset. Silloin kun yrityksen kaikissa valmistusyksiköissä valmistetaan samaa tuoteversiota, yksiköt voivat auttaa toisiaan komponenttien hankinnassa. Tuotemuutokset voidaan tällöin toteuttaa nopeammin.

Abstract The present dissertation deals with initial synchronization in Code Division Multiple Access (CDMA) networks. In the first part of this thesis an extensive and up-to-date review of the literature is presented. The basic theory of code acquisition as well as different techniques and structures used to achieve the initial synchronization are discussed. A survey of the most common theoretical approaches allowing performance characterization of the acquisition process is included. The effect of noise, interference, carrier Doppler, multipath propagation, fading and data modulation on system performance are reviewed. Advanced code acquisition approaches exploiting interference suppression techniques and multiple antennas are also described. A summary of the results obtained within the area of code acquisition in CDMA networks is also embraced by this thesis. The distinctive assumption is to consider the actual variable effect of multiple access interference on the delay-domain search process, instead of the usual constant approximation. Three directions of research are followed. Models for code acquisition in quasi-synchronous and asynchronous CDMA networks are first developed and analysed. Closed-form expressions for the main performance figures of the acquisition process are derived and analysed. Results show a strong dependence of the mean acquisition time with the nature of the multiple access interference. In the second area of research the previous results are extended to consider code acquisition with a multi-branch (Rake) receiver in a multipath channel. A generic model for Rake receiver code acquisition is considered and developed, in which the synchronization takes place in two phases. The first detected path is allocated to the first finger during the initial synchronization phase, whereas the remaining fingers are successively allocated to other available paths in the postinitial synchronization phase. Performance measures for this acquisition process are also derived and analysed. Finally, based on the use of an antenna array and beamforming techniques, conventional delay-domain code acquisition is extended to the angular domain, resulting in a two-dimensional (delay-angle) search. This technique is found to be feasible, outperforming the synchronization approach exploiting a single-antenna. It is found that there exists an optimal number of antennas that minimises the mean acquisition time. Two-dimensional code acquisition is studied in a variety of scenarios, including single and multipath channels, fixed and fading channels, and with uniform and nonuniform spatial distributions of interference. Different two-dimensional search strategies are studied. A clear dependence of acquisition performance with the search strategy and the particular distribution of interference is pointed out. The performance of two-dimensional code acquisition is found to be seriously deteriorated by the presence of spatially nonuniform interference. Schemes based on search strategy and adaptive detector structures are considered and analysed to combat the performance degradation in the mentioned case. A comparative study of code acquisition exploiting multiple antennas is also presented.

Moderne Experimente in der Kurzzeitphysik erfordern eine hochpräzise Synchronisation der beteiligten Strahlungsquellen, um dynamische Prozesse und atomare Strukturen aufzulösen. Die Komplexität und räumliche Ausdehnung einer linearbeschleuniger-getriebenen Strahlungsquelle wie ELBE verlangt nach neuen Konzepten, um die anspruchsvollen Anforderungen zu erfüllen. Kernbestandteile der vorliegenden Arbeit sind die Konzeption, der Aufbau und die Inbetriebnahme eines gepulsten optischen Synchronisationssystems zur Verteilung eines Phasenreferenzsignals. Dieses System bildet eine wesentliche Grundvoraussetzung für wissenschaftliche Experimente mit einer Auflösung im Bereich von wenigen zehn Femtosekunden. Darüber hinaus wurde der Prototyp eines Ankunftszeitmonitors am ELBE-Beschleuniger entwickelt und charakterisiert. Mit diesem Diagnoseelement wurden erstmals Messungen der Elektronenpulsankunftszeit mit einer Auflösung von wenigen Femtosekunden am ELBE-Strahl möglich. Die implementierte Datenanalyse erlaubt einzelpulsaufgelöste Messzyklen mit bisher unerreichter spektraler Bandbreite am kontinuierlichen (CW) Elektronenstrahl. Ferner wurde eine Methode zur Datenerfassung entwickelt, die unter Verwendung der Lockin-Technik besonders rauscharme Messungen hervorbringen kann. Abschließend wurde der ELBE-Beschleuniger hinsichtlich Ankunftszeit und Energiestabilität umfassend untersucht. Dabei wurden die erweiterten Möglichkeiten, die ELBE als CW-Beschleuniger bietet, ausgeschöpft. Der Fokus lag besonders auf der spektralen Analyse der Störungen bei verschiedenen Kompressionszuständen der Elektronenpulse. Diese methodische Untersuchung wurde sowohl für den thermionischen Injektor als auch für die supraleitende Fotoelektronenquelle durchgeführt. Die präsentierten Messergebnisse ermöglichen ein erweitertes Verständnis für die wirkenden Störmechanismen während der Elektronenpulspropagation und stellen den Ausgangspunkt für systematische Verbesserungen der Strahlqualität dar. Ein beschriebener Grundlagenversuch belegt, wie der ELBE-Elektronenstrahl in Zukunft aktiv stabilisiert werden kann, um die erforderliche Zeitauflösung zu erreichen. Intrinsische Strahlinstabilitäten können dadurch signifikant reduziert werden.

The aim of this dissertation was the design, implementation and performance evaluation of a Recursive Least Squares (RLS), lattice based, adaptive, multidimensional, decision feedback equaliser (DFE) for the spectrally efficient four-dimensional digital modulation technique, re¬ferred to as Quadrature-Quadrature Phase-Shift Keying, Q2pSK. Q2PSK constitutes a relatively new modulation technique, and the application of adaptive equalisation to this technique has not yet been considered in the open literature. This dissertation represents an in depth study into the Q2PSK modulation technique, as well as the optimal implementation, in simulation, of such a modem to aid the inclusion of the adap¬tive lattice DFE, for application to high speed mobile digital communication over the V /UHF channel in the presence of multi path propagation. Specific aspects of synchronization applicable to this modem platform are also addressed. An in depth study was also conducted into the realisation of a V /UHF channel simulation, capable of producing a Ricean and/or Rayleigh fad¬ing multipath propagation environment for the evaluation of the modem platform and adaptive equaliser structure. The theoretical analysis of the effect of multi path on a Q2PSK signal led to the correct design of the adaptive lattice structure, as well as the correct interfacing of the equaliser to the receiver platform. The performance of the proposed synchronisation strategies, in tandem with the equalisation technique were evaluated for several static, as well as fading multipath channels. The simulation results obtained show the equaliser operates correctly, and can give large performance gains over the static matched filter (matched to the transmitted waveform) implementation of the modem platform. Several simulations were specifically designed to highlight the performance limitations of the adaptive equalisation technique. / Dissertation (MEng (Digital Communication))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

In the past decade or so, significant advances were made in the field of Future Internet Architecture (FIA) design. Undoubtedly, the size of Future Internet will increase tremendously, and so will the complexity of its users’ behaviors. This advancement means most of future Internet applications and services can only achieve and demonstrate full potential on a large-scale basis. The development of network testbeds that can validate key design decisions and expose operational issues at scale is essential to FIA research. In conjunction with the development and advancement of FIA, cyber-infrastructure testbeds have also achieved remarkable progress. For meaningful network studies, it is indispensable to utilize cyber-infrastructure testbeds appropriately in order to obtain accurate experiment results. That said, existing current network experimentation is intrinsically deficient. The existing testbeds do not offer scalability, flexibility, and realism at the same time. This dissertation aims to construct a hybrid system of conducting at-scale network studies and experiments by exploiting the distributed computing ability of current testbeds. First, this work presents a synchronization of parallel discrete event simulation that offers the simulation with transparent scalability and performance on various high-end computing platforms. The parallel simulator that we implement is configured so that it can self-adapt for the performance while running on supercomputers with disparate architectures. The simulator could be used to handle models of different sizes, varying modeling details, and different complexity levels. Second, this works addresses the issue of researching network design and implementation realistically at scale, through the use of distributed cyber-infrastructure testbeds. An existing symbiotic approach is applied to integrate emulation with simulation so that they can overcome the limitations of physical setup. The symbiotic method is used to improve the capabilities of a specific emulator, Mininet. In this case, Mininet can be used to run applications directly on the virtual machines and software switches, with network connectivity represented by detailed simulation at scale. We also propose a method for using the symbiotic approach to coordinate separate Mininet instances, each representing a different set of the overlapping network flows. This approach provides a significant improvement to the scalability of the network experiments.

No description available.

Context represents any knowledge obtained from Wireless Sensor Networks (WSNs) about the object being monitored (such as time and location of the sensed events). Time and location are important constituents of context as the information about the events sensed in WSNs is comprehensive when it includes spatio-temporal knowledge. In this thesis, we first concentrate on the development of a suite of lightweight algorithms on temporal event ordering and time synchronization as well as localization for WSNs. Then, we propose an energy-efficient clustering routing protocol for WSNs that is used for message delivery in the former algorithm. The two problems - temporal event ordering and synchronization - are dealt with together as both are concerned with preserving temporal relationships of events in WSNs. The messages needed for synchronization are piggybacked onto the messages exchanged in underlying algorithms. The synchronization algorithm is tailored to the clustered topology in order to reduce the overhead of keeping WSNs synchronized. The proposed localization algorithm has an objective of lowering the overhead of DV-hop based algorithms by reducing the number of floods in the initial position estimation phase. It also randomizes iterative refinement phase to overcome the synchronicity of DV-hop based algorithms. The position estimates with higher confidences are emphasized to reduce the impact of erroneous estimates on the neighbouring nodes. The proposed clustering routing protocol is used for message delivery in the proposed temporal algorithm. Nearest neighbour nodes are employed for inter-cluster communication. The algorithm provides Quality of Service by forwarding high priority messages via the paths with the least cost. The algorithm is also extended for multiple Sink scenario. The suite of algorithms proposed in this thesis provides the necessary tool for providing spatio-temporal context for context-aware WSNs. The algorithms are lightweight as they aim at satisfying WSN's requirements primarily in terms of energy-efficiency, low latency and fault tolerance. This makes them suitable for emergency response applications and ubiquitous computing.

Cette thèse porte sur la résolution de problèmes de transport qui intègrent des contraintes temporelles considérant les fenêtres de temps, la synchronisation des visites et l’équilibrage des services. Ces problèmes trouvent plusieurs applications dans le monde réel.L’objectif de nos recherches est l’élaboration de nouvelles méthodes de résolution pour les problèmes considérés en examinant leur performance avec une étude comparative par rapport aux différentes approches de la littérature. Deux variantes sont traitées. Le premier cas étudie le Problème de Tournées de Véhicules avec Fenêtres de Temps (VRPTW). Nous proposons de nouveaux prétraitements et bornes inférieures pour déterminer le nombre de véhicules nécessaires en s’inspirant de travaux menés en ordonnancement (raisonnement énergétique) et d’autres problèmes combinatoires comme la clique maximum et les problèmes de bin-packing. Nous présentons également un algorithme d’optimisation par essaim particulaire qui traite de la minimisation du nombre de véhicules puis de celle du temps de trajet total. Le deuxième cas étudie le Problème de Tournées de Véhicules avec des Fenêtres de Temps et des Visites Synchronisées (VRPTWSyn). Nous proposons plusieurs méthodes basées sur des approches heuristiques et des formulations linéaires avec l’incorporation d’inégalités valides pour tenir compte de la contrainte de synchronisation. / This dissertation focuses on vehicle routing problems, one of the major academic problems in logistics. We address NP-Hard problems that model some realworld situations particularly those with different temporal constraints including time windows, visit synchronization and service balance.The aim of this research is to develop new algorithms for the considered problems,investigate their performance and compare them with the literature approaches.Two cases are carried out. The first case studies the Vehicle Routing Problem with Time Windows (VRPTW). We propose new lower bound methods for the number of vehicles. Then we present a Particle Swarm Optimization algorithm dealing with the Solomon objective. The second case studies the VehicleRouting Problem with Time Windows and Synchronized Visits (VRPTWsyn).Both exact methods and heuristics are proposed and compared to the literature approaches.

Goal of this master thesis is to analyze existing algorithms for ensuring consistency in real-time synchronization of vector graphics between server and multiple clients, testing them, describe main differences and selection of the best for this purpose. The theoretical part is devoted to realtime comunication over HTTP, to WebSockets, to concurrency algorithms and to basics of application architecture. The practical part describes the technology used in this thesis, as well as actual application design a its implementation. The result of this thesis is an overview of concurrency algorithms, the choise of technology for real-time communication between server and multiple clients and implementation of selected technologies and algorithms in Node.js application.

The topic of this paper is creation of new ServiceNow development tool. ServiceNow is cloud based IT service support management tool. It is widely customizable, mainly by creating scripts. The problem is that scripts are created via web browser, which is not very user friendly. The main goal of this paper is to design better solution for creating scripts in ServiceNow and implement it for selected integrated development environment - Eclipse. Created development tool should support these operations - checking out scripts from ServiceNow to local workspace, editing them in special editor, updating them to newest version and committing them back to ServiceNow with check that work of some other developer is not overwritten. The main contribution of this paper is created ServiceNow development tool that provides better user experience than existing solutions. This paper is only start of development. It will continue in the future.