• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2022
  • 519
  • 135
  • 117
  • 62
  • 48
  • 47
  • 47
  • 47
  • 47
  • 47
  • 45
  • 24
  • 22
  • 19
  • Tagged with
  • 3320
  • 1086
  • 717
  • 710
  • 626
  • 618
  • 441
  • 342
  • 317
  • 315
  • 287
  • 278
  • 272
  • 251
  • 233
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
471

An algebraic approach of optical performance monitoring in all-optical networks.

January 2005 (has links)
Ho Siu Ting. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 84-87). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Drivers for performance monitoring --- p.1 / Chapter 1.2 --- Migration of performance monitoring --- p.1 / Chapter 1.3 --- OPM categories --- p.3 / Chapter 1.4 --- Review on OSNR monitoring --- p.6 / Chapter 1.4.1 --- Polarization approach --- p.6 / Chapter 1.4.1.1 --- Polarization extinction --- p.6 / Chapter 1.4.1.2 --- Degree-of-polarization (DOP) analysis --- p.7 / Chapter 1.4.2 --- Interferometric approach --- p.7 / Chapter 1.4.3 --- RF spectral analysis approach --- p.8 / Chapter 1.5 --- Review on PMD monitoring --- p.8 / Chapter 1.5.1 --- DOP approach --- p.8 / Chapter 1.5.2 --- RF spectral analysis approach --- p.9 / Chapter 1.5.3 --- Arrival time measurement approach --- p.9 / Chapter 1.6 --- Objective of the thesis --- p.9 / Chapter 1.7 --- Linear expressions of optical impairments --- p.10 / Chapter Chapter 2 --- Monitoring of Linearly Accumulated Impairments in Unidirectional Links and Nodes --- p.12 / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Problem formulation --- p.12 / Chapter 2.3 --- Probing scheme --- p.19 / Chapter 2.3.1 --- Two-link-connected networks --- p.19 / Chapter 2.3.1.1 --- Ring network --- p.20 / Chapter 2.3.1.2 --- General two-link-connected network --- p.25 / Chapter 2.3.2 --- Tree networks --- p.28 / Chapter 2.3.3 --- Networks with bridges --- p.33 / Chapter 2.3.4 --- Illustrative example --- p.36 / Chapter 2.4 --- Single-fault localization --- p.42 / Chapter 2.5 --- Conclusion --- p.43 / Chapter Chapter 3 --- Monitoring of Linearly Accumulated Impairments in Directional Links --- p.45 / Chapter 3.1 --- Introduction --- p.45 / Chapter 3.2 --- Problem formulation --- p.45 / Chapter 3.3 --- Feasibility analysis --- p.48 / Chapter 3.4 --- Probing scheme --- p.50 / Chapter 3.4.1 --- Two-link-connected networks --- p.50 / Chapter 3.4.1.1 --- Probing scheme with only one monitoring module --- p.50 / Chapter 3.4.1.2 --- Optimal location --- p.51 / Chapter 3.4.2 --- Tree networks --- p.56 / Chapter 3.4.3 --- Networks with bridges --- p.57 / Chapter 3.4.4 --- Illustrative example --- p.58 / Chapter 3.5 --- Reliability and fault localization --- p.64 / Chapter 3.5.1 --- Fth-order probing scheme --- p.64 / Chapter 3.5.2 --- Locations of monitoring modules for Fth-order probing scheme --- p.67 / Chapter 3.5.3 --- Fault localization in Fth-ordcr probing scheme --- p.68 / Chapter 3.6 --- Conclusion --- p.69 / Chapter Chapter 4 --- Other Models --- p.70 / Chapter 4.1 --- Introduction --- p.70 / Chapter 4.2 --- Models --- p.70 / Chapter 4.3 --- Probing scheme for El --- p.71 / Chapter 4.4 --- "Necessary locations of monitoring modules for EN2, EN3 and EN4" --- p.72 / Chapter 4.5 --- Conclusion --- p.79 / Chapter Chapter 5 --- Summary and Future Works --- p.81 / Chapter 5.1 --- Summary of the thesis --- p.81 / Chapter 5.2 --- Future works --- p.83 / Bibliography --- p.84 / Appendix - List of publications --- p.88
472

On transmission impairments in optical systems: investigation, suppression and monitoring. / CUHK electronic theses & dissertations collection

January 2005 (has links)
Lu Guowei. / "January 2005." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
473

Optical switch architectures based on conjugate networks. / CUHK electronic theses & dissertations collection

January 2007 (has links)
Firstly, for a optical switch that suffers from the intrinsic crosstalk problem when two optical signals cross at the same switch element, active connections must be node-disjoint in the switching network to avoid crosstalk. Applying a sequence of decomposition and merge operations, called crosstalk-free conjugate transformation, on each switch element to tackle this problem, the network resulting from this transformation is called crosstalk-free conjugate network. By using the numbering schemes of networks, we prove that if the route assignments in the original network are link-disjoint, their corresponding ones in the conjugate network would be node-disjoint. Thus, traditional nonblocking switching networks can be transformed into crosstalk-free optical switches in a routine manner. / Furthermore, we show that crosstalk-free or wavelength interleaving multicast switches can also be obtained from existing nonblocking multicast switches via the same crosstalk-free or wavelength-interleaving conjugate transformation in a straightforward manner, respectively. / On the other hand, high speed and easy integrated arrayed waveguide gratings (AWGs) and tunable wavelength converters (TWCs) are promising optical devices to construct wavelength division multiplexing (WDM) optical switches. In order to practically realize a WDM switch, the core research issue is how to provide wavelength-interleaving connections throughout the entire switch network of these optical devices. In this way, the topological transformation consisting of decomposition and merge operations can convert nonblocking space-division networks into wavelength-interleaving conjugate networks. The principle of this transformation relies on the parallel characters of internal contentions of space switches and wavelength interferences of WDM switches. We show that any nonblocking route assignments in the original space-division network can be mapped into the conjugate network and become wavelength interleaving under this topological transformation. / The emerging all optical network (AON) calls for the realization of high speed (user data rates from 10 Mbps to 10 Gbps), high capacity (∼NTbps) transparent optical network. One of the major obstacles of AON is the deployment of high-speed optical switching systems that can switch optical signals at the rate of several terabits per second. In all optical switches constructed by different optical devices, the crosstalk or wavelength interference may happen when any two optical signals cross at a single optical device or when two signals carried by the same wavelength in a single link, respectively. In the past serval decades, the nonblocking electronic switching networks have been widely studied and a mature theory has been erected. In this thesis, we propose an easy-to-implement conjugate transformation applied to the traditional nonblocking switching networks in two opposite manners to tackle these two problems, respectively. / Deng Yun. / "January 2007." / Adviser: Tony Tong Lee. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6176. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 101-108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
474

The Cost of Sharing Information in a Social World

Ramachandran, Arthi January 2017 (has links)
With the increasing prevalence of large scale online social networks, the field has evolved from studying small scale networks and interactions to massive ones that encompass huge fractions of the world’s population. While many methods focus on techniques at scale applied to a single domain, methods that apply techniques across multiple domains are becoming increasingly important. These methods rely on understanding the complex relationships in the data. In the context of social networks, the big data available allows us to better model and analyze the flow of information within the network. The first part of this thesis discusses methods to more effectively learn and predict in a social network by leveraging information across multiple domains and types of data. We document a method to identify users from their access to content in a network and their click behavior. Even on a macro level, click behavior is often hard to obtain. We describe a technique to predict click behavior using other public information about the social network. Communication within a network inevitably has some bias that can be attributed to individual preferences and quality as well as the underlying structure of the network. The second part of the thesis characterizes the structural bias in a network by modeling the underlying information flow as a commodity of trade.
475

Real-time network traffic classification.

January 2008 (has links)
Wong, Chi Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 78-80). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview on traffic classification algorithms --- p.2 / Chapter 1.1.1 --- Port based approach --- p.2 / Chapter 1.1.2 --- Payload based approach --- p.2 / Chapter 1.1.3 --- Transport layer information based approach --- p.3 / Chapter 1.2 --- Operating model of traffic classification algorithms --- p.3 / Chapter 1.3 --- Previous related works --- p.4 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Network topology and traffic capturing model --- p.5 / Chapter 2.2 --- Proposed Scheme --- p.6 / Chapter 2.3 --- Analysis on different categories --- p.9 / Chapter 3 --- Objectives --- p.11 / Chapter 3.1 --- Computing Power and Memory --- p.11 / Chapter 3.1.1 --- A rough analysis on the complexity --- p.12 / Chapter 3.2 --- Experiments on the complexity --- p.13 / Chapter 3.2.1 --- Operating Model : batch processing --- p.16 / Chapter 4 --- Computing Power and Memory : parallel processing --- p.22 / Chapter 4.1 --- Goals --- p.22 / Chapter 4.2 --- Parallel processing --- p.23 / Chapter 4.3 --- System Architecture --- p.24 / Chapter 4.4 --- Advantage --- p.26 / Chapter 4.5 --- Practical adjustment --- p.29 / Chapter 4.6 --- The alternative System Architecture --- p.30 / Chapter 5 --- Operating Model : from batch processing to online --- p.34 / Chapter 5.1 --- Goals --- p.34 / Chapter 5.2 --- Proposed model --- p.35 / Chapter 5.3 --- Delay comparasion --- p.35 / Chapter 5.4 --- Performance and accuracy issue --- p.38 / Chapter 5.5 --- Trade off between delay and accuracy --- p.43 / Chapter 6 --- Evaluation --- p.46 / Chapter 6.1 --- Final Prototype --- p.46 / Chapter 6.2 --- Online processing --- p.48 / Chapter 7 --- Others --- p.55 / Chapter 7.1 --- Special cases for network topology --- p.55 / Chapter 7.2 --- Further optimizations for BLINC --- p.56 / Chapter 7.3 --- Study on port-based approach --- p.66 / Chapter 7.4 --- Study on the information used in different algorithms --- p.70 / Chapter 7.5 --- Future works --- p.76 / Chapter 8 --- Conclusion --- p.77 / Bibliography --- p.78
476

Infrastructure sharing and access to broadband: the role of policy and regulation

Magagane, Mankakane Violet 07 June 2013 (has links)
Dissertation submitted to the faculty of Commerce, Law and Management, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Management in ICT PR / ABSTRACT Infrastructure sharing is seen an opportunity to reduce the costs of deploying infrastructure and of gearing investment towards underserviced areas. It has since emerged that there is duplication and concentration of infrastructure in urban areas and limited infrastructure in many parts of the country. This complicates the sharing of infrastructure and the effectiveness of the infrastructure sharing instruments on essential facilities, facilities leasing and interconnection regulations in granting access to a wide range of services such as voice and broadband. The purpose of this study is to explore policy and regulatory instruments in infrastructure sharing and access to broadband. The study took into account the literature on policy and regulation and infrastructure sharing, the industry views and considered the trends in infrastructure sharing and the provision of ubiquitous networks to underserviced areas. The study found that network infrastructure sharing has the potential of providing the rapid development of access infrastructure capable of handling high bandwidth requirements suitable for an information society.
477

A computer communications system

Janne, Kim W January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
478

Some problems in queueing theory

Coyle, Andrew James. January 1989 (has links) (PDF)
Bibliography: leaves 147-152.
479

Robust control and state estimation via limited capacity communication networks

Malyavej, Veerachai, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 2006 (has links)
Telecommunication networks become major parts in modern complex control systems recently. They provide many advantages over conventional point-to-point connections, such as the simplification on installation and maintenance with comparatively low cost and the nature requirement of wireless communication in remote control systems. In practice, limited resource networks are shared by multiple controllers, sensors and actuators, and they may need to serve some other information unrelated to control purpose. Consequently, the control system design in networked control systems should be revised by taking communication constraints, for example, finite precision data, time delay and noise in transmission, into account. This thesis studies the robust control and state estimation of uncertain systems, when feedback information is sent via limited capacity communication channels. It focuses on the problem of finite precision data due to the communication constraints. The proposed schemes are based on the robust set-valued state estimation and the optimal control techniques. A state estimation problem of linear uncertain system is studied first. In this problem, we propose an algorithm called coder-decoder for uncertain systems. The coder encodes the observed output into a finite-length codeword and sends it to the decoder that generates the estimated state based on the received codeword. As an illustration, we apply the results in state estimation problem to a precision missile guidance problem using sensor fusion. In this problem, the information obtained from remote sensors is transmitted through limited capacity communication networks to the guided missile. Next, we study a stabilization problem of linear uncertain systems with state feedback. In this problem, the coder-controller scheme is developed to asymptotically stabilize the uncertain systems via limited capacity communication channels. The coder encodes the full state variable into a finite-length codeword and sends it to the controller that drives the system state to the origin. To achieve the asymptotic stability, we use a dynamic quantizer so that quantization noise converges to zero. The results in both state estimation and stabilization problems can handle the problem of finite data rate communication networks in control systems.
480

An Inquiry Into PBNM System Performance Required For Massive Scale Telecommunication Applications

January 2006 (has links)
PBNM systems have been proposed as a feasible techology for managing massive scale applications including telecommunication service management. What is not known is how this class of system performs under carrier-scale traffic loads. This research investigates this open question and concludes, subject to the considerations herein, this technology can provide services to large scale applications. An in depth examination of several inferencing algorithms is made using experimental methods. The inferencing operation has been implicated as the major source of performance problems in rule based systems and we examine this. Moreover, these algorithms are of central importance to current and future context-aware, pervasive, mobile services. A novel algorithm, JukeBox, is proposed that is a correct, general and pure bindspace conjunctive match algorithm. It is compared to the current state of the art algorithm - Rete. We find that Rete is the superior algorithm when implemented using the hashed-equality variant. We also conclude that IO is an important cause of PBNM system performace limitations and is perhaps of more significance than the implicated inferencing operations. However, inferencing can be a bottleneck to performance and we document the factors associated with this. We describe a generally useful policy system benchmarking procedure that provides a visible, repeatable and measurable process for establishing a policy server's service rate characteristics. The service rate statistics, namely (mu) and (sigma), establish the limitations to policy system throughput. Combined with the offered traffic load to the server, using the statistic (lambda), we can provide a complete characterisation of system performance using the Pollaczek-Khinchine function. This characterisation allows us to make simple design and dimensioning heuristics that can be used to rate the policy system as a whole.

Page generated in 0.0914 seconds