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  • 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.
331

Practical Wired Digital Communications Link Analysis

Schmelzer, Raymond Matthew 10 August 2016 (has links)
This thesis deals with the analysis of a Wired High Speed Serial Data Link (PAM2) which is commonly used throughout the data-communications and tele-communications industry. The goal of this study is to build a scalable simulation tool using Matlab that ultimately uses Receiver Bit Error Ratio (BER) as the metric for data link health. This study is also designed to aid in link specification development. The Matlab and theoretical development is broken up into three sections being Transmitter (TX), Channel (Hs) and Receiver (RX). Realistic noise impairments can be added to each section along the signal path creating signal stresses commonly seen in data center applications. The TX function is designed to create random and periodic timing jitter, voltage noise and deterministic pre-distortion filtering effects. For the channel response s-parameters are used as the model result for many commonly seen channel loss and reflection scenarios. The RX model uses signal to noise ratio and vertical eye margin to determine the equalized link BER. The study results show many tradeoffs between noises, RX Equalizer, RX gain and RX BER. The simulation results also reveal that there is no closed form solution for converging the modern closed-eye PAM2 detector.
332

Lntp : the implementation and performance of a new local area network transport protocol

Robinson, James Beresford January 1987 (has links)
In the past it has been convenient to adopt existing long haul network (LHN) protocols for use in local area networks (LANs). However, due to the different operating parameters that exist between these two types of networks, it is not possible for a LHN protocol to fully exploit the characteristics of a LAN. Thus, the need arises for a protocol designed specifically for use in a LAN environment. LNTP is one such transport level protocol. It was designed for exclusive use in LANs, and thus does not incorporate those features which are not relevant to a LAN environment. The result of this is a simpler and more efficient protocol. As well, LNTP employs a novel deferred flow control strategy which minimizes the time that a transmitting process will be blocked. This thesis examines the implementation of LNTP in the 4.2 BSD UNIX operating system. Various measurements are taken, and LNTP's performance is compared to that of TCP/IP, a LHN protocol which is often used in LAN environments. Several formulas are developed to determine the optimum values for various LNTP parameters, and these theoretical results are compared to the experimentally observed values. We conclude that LNTP does indeed outperform TCP/IP. However, due to the overhead of the non-LNTP specific protocol layers, this improvement is not as great as it might be. Nonetheless, LNTP proves itself to be a viable replacement for TCP/IP. / Science, Faculty of / Computer Science, Department of / Graduate
333

Priority CSMA schemes for integrated voice and data transmission

Ching, Kai-Sang January 1988 (has links)
Priority schemes employing the inherent properties of carrier-sense multiple-access (CSMA) schemes are investigated and then applied to the integrated transmission of voice and data. A priority scheme composed of 1-persistent and non-persistent CSMA protocols is proposed. The throughput and delay characteristics of this protocol are evaluated by mathematical analysis and simulation, respectively. The approach of throughput analysis is further extended to another more general case, p-persistent CSMA with two persistency factors, the throughput performance of which had not been analyzed before. Simulations are carried out to study the delay characteristics of this protocol. After careful consideration of the features of the priority schemes studied, two protocols are proposed for integrated voice and data transmission. While their ultimate purpose is for integrated services, they have different application. One of them is applied to local area network; the other is suitable for packet radio network. The distinctive features of the former are simplicity and flexibility. The latter is different from other studies in that collision detection is not required, and that it has small mean and variance of voice packet delay. Performance characteristics of both of these protocols are examined by simulations under various system parameter values. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate
334

A Machine Learning based High-Speed State Estimator for Partially Observed Electric Transmission Systems

January 2020 (has links)
abstract: The accurate monitoring of the bulk transmission system of the electric power grid by sensors, such as Remote Terminal Units (RTUs) and Phasor Measurement Units (PMUs), is essential for maintaining the reliability of the modern power system. One of the primary objectives of power system monitoring is the identification of the snapshots of the system at regular intervals by performing state estimation using the available measurements from the sensors. The process of state estimation corresponds to the estimation of the complex voltages at all buses of the system. PMU measurements play an important role in this regard, because of the time-synchronized nature of these measurements as well as the faster rates at which they are produced. However, a model-based linear state estimator created using PMU-only data requires complete observability of the system by PMUs for its continuous functioning. The conventional model-based techniques also make certain assumptions in the modeling of the physical system, such as the constant values of the line parameters. The measurement error models in the conventional state estimators are also assumed to follow a Gaussian distribution. In this research, a data mining technique using Deep Neural Networks (DNNs) is proposed for performing a high-speed, time-synchronized state estimation of the transmission system of the power system. The proposed technique uses historical data to identify the correlation between the measurements and the system states as opposed to directly using the physical model of the system. Therefore, the highlight of the proposed technique is its ability to provide an accurate, fast, time-synchronized estimate of the system states even in the absence of complete system observability by PMUs. The state estimator is formulated for the IEEE 118-bus system and its reliable performance is demonstrated in the presence of redundant observability, complete observability, and incomplete observability. The robustness of the state estimator is also demonstrated by performing the estimation in presence of Non-Gaussian measurement errors and varying line parameters. The consistency of the DNN state estimator is demonstrated by performing state estimation for an entire day. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020
335

A session layer for the X.400 message handling system

Van der Westhuizen, Eugene Daniel January 1990 (has links)
Bibliography: pages 233-235. / The CCITT X.400 Message Handling System resides in the Application Layer of the seven-layer Reference Model for Open Systems Interconnection. It bypasses the services of the Presentation Layer completely to interact directly with the Session Layer. The objectives of this thesis are to show how the general Session Layer may be tailored to be minimally conformant to the requirements of X. 400; to produce a formal specification of this session layer; and to show how this session layer may be implemented on a real system. The session services required by X. 400 are those of the Halfduplex, Minor Synchronization, Exceptions and Activity Management functional units of the CCITT X.215 Session Service Definition. These services, and particularly their use by X.400, are described in detail. State tables describing these services are derived from the general session service state tables. Those elements of the CCITT X. 225 Session Protocol Specification which are required to provide only those services required by X. 400 are described in detail. State tables describing this session protocol are derived from the general session protocol state tables. A formal specification of the session layer for X.400 is presented using the Formal Description Technique Estelle. This specification includes a complete session entity, which characterizes the entire session layer for X.400. A session entity for supporting X.400 is partially implemented and interfaced to an existing X.400 product on a real system. Only the Session Connection Establishment Phase of the session protocol is implemented to illustrate the technique whereby the entire session protocol may be implemented. This implementation uses the C programming language in the UNIX operating system environment.
336

PC-based bit error rate analyser for a 2 Mbps data link

Bayley, Gwain 22 November 2016 (has links)
No description available.
337

Efficient Support for Application-Specific Video Adaptation

Huang, Jie 01 January 2006 (has links)
As video applications become more diverse, video must be adapted in different ways to meet the requirements of different applications when there are insufficient resources. In this dissertation, we address two sorts of requirements that cannot be addressed by existing video adaptation technologies: (i) accommodating large variations in resolution and (ii) collecting video effectively in a multi-hop sensor network. In addition, we also address requirements for implementing video adaptation in a sensor network. Accommodating large variation in resolution is required by the existence of display devices with widely disparate screen sizes. Existing resolution adaptation technologies usually aim at adapting video between two resolutions. We examine the limitations of these technologies that prevent them from supporting a large number of resolutions efficiently. We propose several hybrid schemes and study their performance. Among these hybrid schemes, Bonneville, a framework that combines multiple encodings with limited scalability, can make good trade-offs when organizing compressed video to support a wide range of resolutions. Video collection in a sensor network requires adapting video in a multi-hop storeand- forward network and with multiple video sources. This task cannot be supported effectively by existing adaptation technologies, which are designed for real-time streaming applications from a single source over IP-style end-to-end connections. We propose to adapt video in the network instead of at the network edge. We also propose a framework, Steens, to compose adaptation mechanisms on multiple nodes. We design two signaling protocols in Steens to coordinate multiple nodes. Our simulations show that in-network adaptation can use buffer space on intermediate nodes for adaptation and achieve better video quality than conventional network-edge adaptation. Our simulations also show that explicit collaboration among multiple nodes through signaling can improve video quality, waste less bandwidth, and maintain bandwidth-sharing fairness. The implementation of video adaptation in a sensor network requires system support for programmability, retaskability, and high performance. We propose Cascades, a component-based framework, to provide the required support. A prototype implementation of Steens in this framework shows that the performance overhead is less than 5% compared to a hard-coded C implementation.
338

Discrete fiber Raman amplifiers for agile all-photonic networks

Gest, Johann. January 2007 (has links)
No description available.
339

Development and use of a miniature ultrasonic pulser receiver

Nguyen, San Boi. January 2008 (has links)
No description available.
340

A prototype investigation of a multi-GHz multi-channel analog transient recorder /

Kohnen, William. January 1986 (has links)
No description available.

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