152 research outputs found

    High Frequency Ethernet Cabling Analysis and Optimization

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    This thesis provides analytical and forensic tools for data cabling, with particular focus on Ethernet cabling to assist designers and those involved in deployments in analyzing cable performance and the reasons behind the actual performance obtained. The need for higher bandwidth to accommodate increasing demand for multimedia services and data centers network infrastructure led to the formation of IEEE P802.3bq to create standards for 40GBASE-T over twisted pair cables. The 40GBASE-T is expected to offer bandwidth of up to 2000MHz over a maximum channel length of 30m. The research investigated means of predicting key performance parameters in Ethernet cabling standardization using the 40GBASE-T as an example. The performance parameters prediction method provided is equally applicable to ongoing and future high data rate Ethernet cabling standardization such as the 2.5/5GBASE-T and 50/100GBASE-T. Another problem in the Ethernet networking world is the availability of counterfeit and non-standards compliant twisted pair cables in the market. The significant amount of communications cables in the market containing copper clad aluminum cable or other non-standards compliant conductors disguised as Category 6 cables can pose serious problems to companies’ networks, the contractors or the installers. This is in view of the growing demand for internet of things (IOT) services that makes it imperative to have a reliable Ethernet driven communication network to support the required infrastructure. This thesis therefore, provides techniques that can be used to evaluate cables key performance parameters using the Feature Selective Validation method and the Kolmogorov-Smirnov (KS) test. The technique can help engineers avoid subjective judgement and make objective decisions in the selection of cables. The research provided a technique that can be used to reverse engineer impedance profile from the return loss measurement of Ethernet cables using genetic algorithms. The method can be applied in situations where time domain tests are inaccessible or only simple (magnitude) tests in the frequency domain are available and there is the need for impedance profiles of cables to evaluate their performance or physical integrity before or after installation. The method can also be useful where only simple (magnitude) tests are the only historical data available for the cables and facilities for time domain reflectometry measurements are inaccessible. This research also presented a method of evaluating and predicting NEXT in unshielded twisted pair (UTP) using Category 6 cables as an example. The results obtained from the evaluation were used to provide crosstalk parameters for fast NEXT prediction in Category 6 (UTP) cables. The research used the measured NEXT of three Category 6 (UTP) cables from different manufacturers for evaluation and validation. The evaluation and modeling method can thus be useful to engineers investigating NEXT in the design of data communication systems

    East Lancashire Research 2007

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    Impacto del aprendizaje basado en proyectos en las competencias de redes y comunicaciones I en estudiantes de ingeniería, Lima 2020

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    La presente investigación de titulo “Impacto del aprendizaje basado en proyectos en las competencias de redes y comunicaciones I en estudiantes de Ingeniería, Lima 2020”, se elaboró con el objetivo de determinar el impacto del aprendizaje basado en proyectos en las competencias de redes y comunicaciones I, en estudiantes de Ingeniería, Lima 2020. El estudio fue de tipo aplicada, diseño cuasiexperimental, se trabajó con una población finita conformada por 39 estudiantes del VI ciclo de Ingeniería, se aplicó una prueba objetiva para medir el impacto del aprendizaje basado en proyectos en las competencias de redes y comunicaciones I, validado por 5 especialistas; tres metodológos y dos temáticos. Los resultados de la investigación determinaron la relación estadísticamente significativa del aprendizaje basado en proyecto y las competencias de redes y comunicaciones I en estudiantes de Ingeniería, Lima 2020, con valores en el pretest de Z=- ,498 mayor a -1,96 (punto crítico) y nivel de significancia p-valor=0,618 mayor que α=0,05 (p>α) y luego con valores en el postest de Z= - 4,488 menor a -1,96 (punto crítico) y nivel de significancia p-valor=0,000 menor que α=0,05 (p<α), por lo cual el aprendizaje basado en proyectos impacta positiva y significativamente en las competencias de redes y comunicaciones I, en estudiantes de Ingeniería, Lima 2020, comprobando la hipótesis alterna y rechazando la hipótesis nula. conocimientos para solucionar problemas de diseño de red de área local, implementación de la convergencia de la red, administración de redes Teniendo la conclusión que la aplicación de la metodología aprendizaje basado en proyectos ha demostrado que causo un impacto positivo y significativo en las competencias de redes y comunicaciones I

    Probabilistic risk assessment of electrical substations

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    This thesis is concerned with the development of probabilistic risk assessment for substation earthing systems. A number of key parameters have been studied in detail which led to the development of a new approach that incorporates the recommendations of applicable standards and uses historical system fault data to take account of the probabilistic nature of load, protection systems and grid characteristics. In this work, an in-depth appraisal of existing standards has led to the development of safety-limit surfaces that can be used to quantify the benefits/disadvantages of particular earthing standards. The investigation has revealed that there are substantial differences between the recommended values of tolerable voltages attributed to a combination of factors: (i) difference in assumed tolerable body current (ii) differences in the parameters of the electrocution circuit (iii) differences in the predicted touch voltage and (iv) differences in the assumed worst-case shock location. The electricity industry, like other industries, is looking to reduce risk to minimum feasible while maintaining costs of mitigation within acceptable limits. Therefore, a more rigorous and comprehensive procedure of probabilistic risk assessment of the earthing systems is required. In order to achieve this, a detailed analysis of all parameters was undertaken in this work using more representative accidental circuits and parameters extracted from historical system fault data, provided by the collaborating transmission companies. These parameters were modelled and integrated into the proposed probabilistic risk assessment process. Work within this investigation on improving accuracy of calculation of heart fibrillation has led to the development of a probability surface of ventricular fibrillation and a computerised process that determines an accurate probability for a given body current and shock duration. This procedure takes into consideration the body current path and eliminates reading errors or assumptions that could result into conservative or optimistic conclusions. The above fundamental investigations on parameters affecting the overall risk were implemented in a new computerised risk assessment procedure CRAFTS suitable for transmission systems. CRAFTS allows a probabilistic risk assessment of the system under investigation. The application integrates the recent developments in the latest standard IEC 60479-1 and the developed probability surface of ventricular fibrillation. A case study performed on a typical grid has shown that the developed program is very useful when applying sensitivity analysis of the various parameters of the system and accidental circuit. The proposed full probabilistic risk assessment method incorporates the earthing system simulation results performed by specialised software, namely CDEGS, making it possible to simulate different electrocution scenarios throughout the substation instead of assuming a 'worst case scenario' and exposure to maximum possible voltages. Overall, the research in this thesis, offers an integrated solution of probabilistic risk assessment of earthing systems in aid of sound cost/benefit analysis and decision making.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Underwater Vehicles

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    For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties

    Contribution to the study of the vulnerability of critical systems to Intentional Electromagnetic Interference (IEMI)

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    The progress of high power electromagnetic (HPEM) sources during the late 1990s raised the concern in the electromagnetic compatibility (EMC) community that they could be deployed for criminal purposes to interfere with the operation of modern electronic systems. It is well established that sufficiently intense electromagnetic fields can cause upset or damage in electronic systems and therefore, can affect almost every critical infrastructure (CI) that is based on information and communication technologies (ICT). This field of study was initially known as electromagnetic terrorism, but was changed to the more encompassing term of intentional electromagnetic interference (IEMI). This thesis is a contribution to the assessment techniques of the vulnerability of CIs against IEMI. In order to quantify their impact, the electromagnetic environment created by IEMI sources needs to be characterized, the susceptible components and subsystems of the CIs should be identified, and the expected disturbances have to be evaluated. We present a qualitative methodology to carry out the so-called IEMI audit of a facility. Given the complexity of the problem, it was decided that the vulnerability of an infrastructure should be evaluated in a qualitative manner by regarding the consequences of interrupting the normal provision of a service, the probability of occurrence of an IEMI attack, and the preparedness of the infrastructure to withstand an attack. An updated survey and classification of potential IEMI sources that were collected from a large number of scientific publications is presented. The sources have been classified according to their electromagnetic environment, their transportability, technological development, and cost level. The expected disturbances due to a high frequency illumination of representative cabling systems inside an office were studied through measurements performed using a plastic raceway containing several types of cables found in commercial buildings. The tests revealed that at low and intermediate frequencies, low voltage power cables are more susceptible compared to telephone or network cables. At high frequencies, the coupling is dominated by connector apertures and discontinuities and load unbalance. The applicability of the TL theory in evaluating differential mode signals in two-wire lines floating above a ground plane was studied through comparisons with full-wave simulations. The results showed that the validity of the TL theory is conditioned upon an electrically short distance between the differential wires, regardless of the distances above the ground plane. TL theory is also used to assess the effect of conductive and dielectric losses in the dispersion of injected IEMI signals along power and communication cables as a function of the propagation length. A TL model of the low voltage power cabling of the plastic raceway was developed and in order to validate the models, the numerical results were compared against measurements obtained using frequency and time domain techniques. General considerations and guidelines for the application of the TL theory for evaluating the overall transfer impedance of complex cable assemblies are given. The obtained simulation results were found to be in good agreement with the experimental data up to frequencies of about 500 MHz. Finally, an improved model for estimating the transfer impedance of a two-layer braided shield is also proposed and validated using experimental data

    Highly redundant and fault tolerant actuator system: control, condition monitoring and experimental validation

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    This thesis is concerned with developing a control and condition monitoring system for a class of fault tolerant actuators with high levels of redundancy. The High Redundancy Actuator (HRA) is a concept inspired by biomimetics that aims to provide fault tolerance using relatively large numbers of actuation elements which are assembled in parallel and series configurations to form a single actuator. Each actuation element provides a small contribution to the overall force and displacement of the system. Since the capability of each actuation element is small, the effect of faults within the individual element of the overall system is also small. Hence, the HRA will gracefully degrade instead of going from fully functional to total failure in the presence of faults. Previous research on HRA using electromechanical technology has focused on a relatively low number of actuation elements (i.e. 4 elements), which were controlled with multiple loop control methods. The objective of this thesis is to expand upon this, by considering an HRA with a larger number of actuation elements (i.e. 12 elements). First, a mathematical model of a general n-by-m HRA is derived from first principles. This method can be used to represent any size of electromechanical HRA with actuation elements arranged in a matrix form. Then, a mathematical model of a 4-by-3 HRA is obtained from the general n-by-m model and verified experimentally using the HRA test rig. This actuator model is then used as a foundation for the controller design and condition monitoring development. For control design, two classical and control method-based controllers are compared with an H_infinity approach. The objective for the control design is to make the HRA track a position demand signal in both health and faulty conditions. For the classical PI controller design, the first approach uses twelve local controllers (1 per actuator) and the second uses only a single global controller. For the H_infinity control design, a mixed sensitivity functions is used to obtain good tracking performance and robustness to modelling uncertainties. Both of these methods demonstrate good tracking performance, with a slower response in the presence of faults. As expected, the H_infinity control method's robustness to modelling uncertainties, results in a smaller performance degradation in the presence of faults, compared with the classical designs. Unlike previous work, the thesis also makes a novel contribution to the condition monitoring of HRA. The proposed algorithm does not require the use of multiple sensors. The condition monitoring scheme is based on least-squares parameter estimation and fuzzy logic inference. The least-squares parameter estimation estimates the physical parameters of the electromechanical actuator based on input-output data collected from real-time experiments, while the fuzzy logic inference determines the health condition of the actuator based on the estimated physical parameters. Hence, overall, a new approach to both control and monitoring of an HRA is proposed and demonstrated on a twelve elements HRA test rig

    An Adaptive Resonance Theory Neural Network (ART NN)-based fault diagnosis system: A Case Study of gas turbine system in Resak Development Platform

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    The project introduces a case study of a real gas turbine system in Resak Development Platform. There are two main objectives of this project. The first objective is aimed to achieve an online fault diagnosis model using Adaptive Resonance Theorem (ART) as a considered option to avoid potential faults happen during plant system and process. The second objective is focused on a solution to improve the maintenance plan for the gas turbine system to be more economical yet still maintaining its safety level

    Prediction of combustion induced vibration in rocket motors

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    Issued as Program plan, Monthly progress report 1-11, and Final report, Project no. E-16-61

    The doctoral research abstracts. Vol:7 2015 / Institute of Graduate Studies, UiTM

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    Foreword: The Seventh Issue of The Doctoral Research Abstracts captures the novelty of 65 doctorates receiving their scrolls in UiTM’s 82nd Convocation in the field of Science and Technology, Business and Administration, and Social Science and Humanities. To the recipients I would like to say that you have most certainly done UiTM proud by journeying through the scholastic path with its endless challenges and impediments, and persevering right till the very end. This convocation should not be regarded as the end of your highest scholarly achievement and contribution to the body of knowledge but rather as the beginning of embarking into high impact innovative research for the community and country from knowledge gained during this academic journey. As alumni of UiTM, we will always hold you dear to our hearts. A new ‘handshake’ is about to take place between you and UiTM as joint collaborators in future research undertakings. I envisioned a strong research pact between you as our alumni and UiTM in breaking the frontier of knowledge through research. I wish you all the best in your endeavour and may I offer my congratulations to all the graduands. ‘UiTM sentiasa dihati ku’ / Tan Sri Dato’ Sri Prof Ir Dr Sahol Hamid Abu Bakar , FASc, PEng Vice Chancellor Universiti Teknologi MAR
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