Дисертації з теми "Isolation Systems"
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1
Mansour, Mohamed S. "Behavior Isolation in Enterprise Systems." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14613.
Повний текст джерелаАнотація:
A barrier to creating the platform-independent services envisioned by middleware-based development infrastructures is the level of performance robustness of the distributed applications created with them, in lieu of unpredictable variations in application behavior or in the resources available for satisfying user requests. Our goal is to improve the behavior locality of distributed applications and to prevent performance (mis-)behaviors from spilling across certain boundaries, since such spillage weakens behavior diagnoses and/or weakens or disables the effects of locally applied control or management methods. Toward these ends, we develop a novel software abstraction, termed {em isolation points} (I-points), which can be used to isolate application components or subsystems from each other.
The main contributions of this work are Isolation Points, which are software abstractions for monitoring and understanding dynamic runtime behaviors to better isolation application components hence creating more robust distributed applications. Two concrete artifacts using I-points also developed in this thesis are: I(solation)-RMI and I(solatoin)-Queue. I-RMI demonstrates the utility of isolation points in J2EE's RMI-IIOP domain. I(solation)-Queue applies isolation points to message passing systems.
2
Manarbek, Saruar. "Study of base isolation systems." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82820.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 55-56).
The primary objective of this investigation is to outline the relevant issues concerning the conceptual design of base isolated structures. A 90 feet high, 6 stories tall, moment steel frame structure with tension cross bracing is used to compare the response of both fixed base and base isolated schemes to severe earthquake excitations. Techniques for modeling the superstructure and the isolation system are also described. Elastic time-history analyses were carried out using comprehensive finite element structural analysis software package SAP200. Time history analysis was conducted for the 1940 El Centro earthquake. Response spectrum analysis was employed to investigate the effects of earthquake loading on the structure. In addition, the building lateral system was designed using the matrix stiffness calibration method and modal analysis was employed to compare the intended period of the structure with the results from computer simulations. Base isolation proves to be effective in reducing the induced inertia forces on a structure by increasing the effective period of oscillation. Keywords: Base Isolation, time history analysis, response spectrum analysis, matrix stiffness calibration method.
by Saruar Manarbek.
M.Eng.
3
Behrens, Diogo. "Error isolation in distributed systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-203428.
Повний текст джерелаАнотація:
In distributed systems, if a hardware fault corrupts the state of a process, this error might propagate as a corrupt message and contaminate other processes in the system, causing severe outages. Recently, state corruptions of this nature have been observed surprisingly often in large computer populations, e.g., in large-scale data centers. Moreover, since the resilience of processors is expected to decline in the near future, the likelihood of state corruptions will increase even further.
In this work, we argue that preventing the propagation of state corruption should be a first-class requirement for large-scale fault-tolerant distributed systems. In particular, we propose developers to target error isolation, the property in which each correct process ignores any corrupt message it receives.
Typically, a process cannot decide whether a received message is corrupt or not. Therefore, we introduce hardening as a class of principled approaches to implement error isolation in distributed systems. Hardening techniques are (semi-)automatic transformations that enforce that each process appends an evidence of good behavior in the form of error codes to all messages it sends. The techniques “virtualize” state corruptions into more benign failures such as crashes and message omissions: if a faulty process fails to detect its state corruption and abort, then hardening guarantees that any corrupt message the process sends has invalid error codes. Correct processes can then inspect received messages and drop them in case they are corrupt.
With this dissertation, we contribute theoretically and practically to the state of the art in fault-tolerant distributed systems. To show that hardening is possible, we design, formalize, and prove correct different hardening techniques that enable existing crash-tolerant designs to handle state corruption with minimal developer intervention. To show that hardening is practical, we implement and evaluate these techniques, analyzing their effect on the system performance and their ability to detect state corruptions in practice.
4
Biteus, Jonas. "Fault Isolation in Distributed Embedded Systems." Doctoral thesis, Linköping : Vehicular Systems, Department of Electrical Engineering, Linköpings universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8774.
Повний текст джерела
5
MATUTTI, ALBERTO CORONADO. "ENERGY FLOW IN VIBRATION ISOLATION SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1951@1.
Повний текст джерелаАнотація:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORSistemas de isolamento de vibrações são utilizados em uma grande variedade de aplicações (automóveis, edifícios, estruturas espaciais como aeronaves, satélites e em máquinas rotativas) para reduzir a transmissão de vibrações mecânicas geradas por equipamentos ou a eles transmitidas pela vizinhança. Um isolamento é obtido inserindo-se um componente mecânico (isolador) que desempenha o papel de vínculo entre o sub-sistema que contém a perturbação e o sub-sistema a ser isolado. Duas são as quantidades geralmente utilizadas para avaliar a efetividade de um sistema de isolamento: a transmissibilidade e a potência. Neste trabalho foi utilizada a potência, sendo esta uma metodologia mais geral que pode ser facilmente utilizada em sistemas complexos, mas que tem a desvantagem de ser de difícil avaliação experimental. Nesta tese, serão simulados numericamente vários sistemas de isolamento passivo por componentes rígidos ou flexíveis, os quais serão modelados por suas respectivas matrizes de mobilidade ou impedância. Estas matrizes serão obtidas por métodos analíticos ou numéricos dependendo da conveniência de cada caso específico. Os projetos tradicionais de sistemas de isolamento geralmente consideram uma excitação unidirecional e avaliam somente algumas componentes da resposta do sistema, isso devido as limitações impostas pelo conceito da transmisibilidde usados nesses projetos. Além disso, eles não dão a devida importância a alguns parâmetros essenciais de configuração geométrica do sistema (localização e ângulo de inclinação dos isoladores, localização dos apoios de base, etc.). No presente trabalho, será mostrada a relevância desses parâmetros mencionados anteriormente no processo de busca das configurações ótimas e também se verá como essas configurações são fortemente dependentes do tipo de excitação do sistema, para isso serão utilizadas combinações de excitações harmônicas multidirecionais.
Vibration isolation systems are used in a large variety of applications (automotive, buil- dings, spatial structures such as aircrafts, satellites and in rotating machines) in order to reduce the transmission of mechanical vibrations from the equipments toward the foun- ation or viceversa. An isolation is obtained inserting a mechanical component (isolator) that acts as a link between the source subsystem and the isolated subsystem. There are two quantities generally used to evaluate the e®ectiveness of a isolation system: the trans-missibility and the power transmitted. In this work, it has been used the power, being this the most generic methodology that can be easily used in complex systems, but it has the disadvantage of a di±cult experimental validation. In this thesis, it will be studied numerically several passive isolation systems with rigid or °exible components, these will be modeled by theirs mobility or impedance matrices. This matrices are achieved by analytical or numerical methods depending of the convenience in each case. Generally traditional projects of isolation systems consider a unidirectional excitation and evaluate only some components of the response system, this occurs for the limitations in the trans-missibility use. Moreover, they do not give an appropriate attention to some parameters of geometrical con¯guration of the system (location and angle inclination of the isolators, location of the base supports, etc.). Herein, it will be shown the relevance of this pa-rameters in the search process of optimal con¯gurations and it will be also see how they depend strongly on the kind of the system excitation, so it will be used some combinations of multidirectional harmonic excitations.
Los sistemas de aislamiento de vibraciones son utilizados en una gran variedad de aplicaciones (automóbiles, edificios, extructuras espaciales como aeronaves y en máquinas rotativas) para reducir la transmisión de vibraciones mecánicas generadas por los equipos. Se obtiene un aislamiento insertando un componente mecánico (aislante) que desempeña el papel de vínculo entre el subsistema que contiene la perturbación y el subsistema que se desea aislar. Generalmente son dos las cantidades utilizadas para evaluar la efectividad de un sistema de aislamiento: la transmisibilidad y la potencia. En este trabajo se utiliza la potencia, pués al ser una metodología más general, puede ser utilizada en sistemas complejos, pero tiene la desventaja de ser de díficil evaluación experimental. En esta tesis, serán simulados numéricamente varios sistemas de aislamiento pasivo por componentes rígidos o flexibles, que serán modelados por sus respectivas matrices de movilidad o impedancia. Estas matrices se obtendrán por métodos analíticos o numéricos según convenga. Los proyectos tradicionales de sistemas de aislamiento, debido a las limitaciones impuestas por el concepto de transmisibilidad utilizada, consideran una excitación unidireccional y evalúan solamente algunas componentes de la respuesta del sistema. Además de eso, ellos no dan la debida importancia a algunos parámetros escenciales de configuración geométrica del sistema (localización y ángulo de inclinación de los aislantes, localización de los apoyos de base, etc.). En este trabajo, se muestra la relevancia de los parámetros mencionados anteriormente en el proceso de búsqueda de las configuraciones óptimas y también se verá como esas configuraciones son fuertemente dependientes del tipo de exitación del sistema. Para esto se utilizaran combinaciones de exitaciones armónicas multidireccionales.
6
SOARES, EDSON JOSE. "ENERGY SPREAD IN VIBRATION ISOLATION SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26507@1.
Повний текст джерелаАнотація:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOMuitas indústrias usam em seus processos materiais viscoplásticos. Esses materiais possuem propriedades que dependem fortemente da temperatura. Não é incomum encontrar processos envolvendo escoamentos não isotérmicos de materiais viscoplásticos. Nesses casos, informações sobre a transferência de calor são extremamente necessárias para um bom atendimento e aperfeiçoamento das operações. Fluidos de perfuração são tipicamente suspensões aquosas, e, por consequência, de natureza viscoplástica.Tais fluidos devem possuir densidade correta para manter a integridade física dos poços e evitar a produção prematura de hidrocarbonetos. Além disso, suas propriedades reológicas devem garantir a capacidade de arraste das partículas de rocha geradas durante o processo de perfuração, com um mínimo de potência de bombeamento. Tais particularidades requerem fluidos com baixas viscosidades a altas taxas de cisalhamento, que ocorrem em regiões próximas à parede, e altas viscosidades quando as taxas de deformação são baixas, o que ocorre na vizinhança do cascalho. Materiais viscoplásticos apresentam este tipo de comportamento. Portanto, o sucesso do processo de extração do petróleo depende do conhecimento e controle das propriedades reológicas dos fluidos de perfuração, as quais são fortemente dependentes da temperatura. Por esse motivo, a determinação do campo de temperatura no fluido de perfuração em escoamento faz-se necessária ainda em nível de projeto, o que só é possível com o conhecimento dos coeficientes de troca de calor. Estuda-se neste trabalho o problema da transferência de calor na região de entrada de escoamentos laminares de fluidos viscoplásticos através de espaços anulares. O comportamento do material é representado pelo modelo do fluido Newtoniano generalizado, com a função viscosidade descrita pela equação de Herschel-Bulkley. As equações de conservação são resolvidas numericamente via o método de volumes finitos. Investigam-se os efeitos (no coeficiente de troca de calor) da tensão limite de escoamento, índice power-law, razão de aspecto e dos números adimensionais de Reynolds e Peclet. Dentre outras conclusões, mostra-se que o números de Nusselt é uma função muito fraca das propriedades reológicas, desviando-se muito pouco dos valores Newtonianos. Surpreendentemente, esta conclusão contrasta-se fortemente com o comportamento observando em escoamentos de materiais viscoplásticos através de tubos. Convém enfatizar a importância desse fato no que tange a projetos de processos.
There are many industries that use in their processes viscoplastic materials. These materials have properties that strongly depend on temperature. It is not uncommon to find processes involving the non-isothermal flow of viscoplastic materials. For these cases, heat transfer information is needed to allow reliable process designs. Drilling muds are typically aqueous suspensions and, consequently, viscoplastic in nature. They must have the correct density to provide the pressure needed for well integrity, and for avoiding premature production of hydrocarbons. Their rheological properties must be such as to aloe carrying the drill chips with a minimum of pumping power. This requires a highly shear-thinning rheological behavior. Also, the success of a well cementing operation depends to a great extent on the knowledge and control of cement rheological properties, which are also temperature dependent. In this work, heat transfer in the entrance-region flow of viscoplastic materials through annular spaces is analyzed. The flow is laminar, and the material is assumed to behave as a Generalized Newtonian fluid, with a Herschel-Bulkley viscosity function. The conservation equations are solved numerically via a finite volume method. The effect on heat transfer of yield stress, power-law exponent, aspect ratio and dimensionless Peclet and Reynolds numbers is investigated. Among other findings, it is shown that the Nusselt number is a rather weak function of the rheological properties, deviating very little from the Newtonian values. Surprisingly, this stands in strong contrast to the behavior observed for flows of viscoplastic materials through tubes. It is worth noting that this finding has important consequences in process design.
7
Ismail, Mohd. "Shock isolation systems incorporating Coulomb friction." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/348953/.
Повний текст джерелаАнотація:
This study investigates a novel approach to the problem of shock isolation. The questions considered are whether friction produces a better performance in terms of reduced response during a shock compared to viscous damping and a lower residual response after the shock. To gain physical insight, a single degree of freedom model with friction applied to the isolated mass is analysed. It serves as a benchmark to the performance of a two degree of freedom model where friction is applied to a secondary mass. The isolation system performance is then quantified. For the two degree of freedom system with an intermediate secondary spring which connects the primary and secondary mass, it is possible to obtain the reduction in the displacement response as good as the single degree of freedom system and at the same time smoother acceleration response compared to the single degree of freedom system. For the purpose of further improvement, a control strategy is introduced to switch on and off friction in both models depending on some response parameters and this is compared to the passive systems. This is the semi active control strategy where friction is changed within a cycle of vibration (discontinuous). The control strategy provides more displacement reduction to ensure the maximum displacement response is much smaller than the base input which cannot be obtained with the passive systems. The practical implementation and experimental validation is presented only for the first stage of the response during the shock. For the practical implementation of the switchable friction, an electromagnet is applied to separate the friction surfaces. Good agreement with the simple theoretical models for both passive and switchable systems is obtained. The reduced displacement and smooth acceleration response were obtained from the experiments with the system used to represent the two degree of freedom model. The issues and limitations in the practical implementation are identified and discussed.
8
Helal, Mohammad Rahat. "Efficient Isolation Enabled Role-Based Access Control for Database Systems." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501627843916302.
Повний текст джерела
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Bryant, H. Victoria. "Modeling atomicity and isolation in workflow systems." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400971431&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Повний текст джерела
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Yu, Dingli. "Fault diagnosis for industrial systems with emphasis on bilinear systems." Thesis, Coventry University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364163.
Повний текст джерела
11
Berba, Michail. "Research of passive low-frequency vibration isolation systems." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130524_145420-89585.
Повний текст джерелаАнотація:
In dissertation discuss about new created dynamic characteristics establishment
of low-frequency (0,7–50 Hz) vibrations isolation system. Presented theoretical
and experimental investigations.
Main goal of dissertation – is creation of dynamic parameters establishment
methods for low-frequency vibration isolation systems and stiff quasi-zero vibrations
isolation system, also investigate their dynamical characteristics and usage
possibilities. Investigation object – low-frequency vibrations isolation mechanical
systems and their dynamic characteristics establishment.
Wish to realize investigation goal, were solved those tasks: 1) In scientifically
literature investigates types of passive and active vibration isolation systems,
constructions, work principals and analyze; 2) Analyzed and theoretically
introduced mechanical conceptions of dynamic characteristics establishment
methods of the vibration isolation systems; 3) Created stiff quasi-zero vibration
isolation method and system based on zeroing of spring stiffness; 4) Done
experimental dynamic characteristics evaluations of optics tables with pneumatic
isolation and stiff quasi-zero vibration isolation systems; 5) Done vibration measurement
uncertainty and given results reliability evaluation.
Dissertation contents introduction, three parts, general conclusion of the results,
used literature and list of author’s themes published dissertations, three
attachments.
In introduction part discuss about investigation problems... [to full text]Disertacijoje nagrinėjamas naujai sukurtų mechaninių pasyviųjų žemojo (0,7–50 Hz) dažnio virpesių izoliavimo sistemų dinaminių charakteristikų nustatymas. Pateikiami teoriniai ir eksperimentiniai tyrimai. Pagrindinis disertacijos tikslas – sukurti mechaninių pasyviųjų žemojo dažnio virpesių izoliavimo sistemų dinaminių parametrų nustatymo metodiką ir kvazinulinio standžio virpesių izoliavimo sistemą, ištirti dinamines jų charakteristikas ir naudojimo galimybes. Tyrimų objektas – žemojo dažnio pasyviosios virpesių izoliavimo mechaninės sistemos ir jų dinaminių charakteristik nustatymas. Siekiant įgyvendinti tyrimų tikslą, išspręsti šie uždaviniai: 1) atlikta mokslinės literatūros apie pasyviųjų ir aktyviųjų virpesių izoliavimo sistemų tipus, konstrukcijas, veikimo principus analizė; 2) išanalizuoti ir pagrįsti mechaninių pasyviųjų virpesių izoliavimo sistemų dinaminių charakteristikų nustatymo metodai; 3) sukurtas kvazinulinio standžio virpesių izoliavimo metodas ir sistema, pagrįsta spyruoklių standžio įnulinimu; 4) atliktas optinių stalų su pneumatiniais izoliatoriais ir kvazinulinio standžio virpesių izoliavimo sistemos eksperimentinis dinaminių charakteristikų įvertinimas; 5) atliktas virpesių matavimo neapibr ėžties ir gautų rezultatų patikimumo įvertinimas. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai, trys priedai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo... [toliau žr. visą tekstą]
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FernaÌndez, Mariano. "Failure detection and isolation in decentralised multisensor systems." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260155.
Повний текст джерела
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Wan, Abdul Aziz Wan Mohd Yusof Rahiman. "Fault detection and isolation : application to pipeline systems." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498676.
Повний текст джерелаАнотація:
In this thesis, the development on Fault Detection and Isolation (FDI) and its application on the nonlinear pipeline based on an observer design techniques are presented. The main focus is to perform the analysis on pipeline systems characteristics and then, systematic approaches are designed for leak diagnosis system based on transient response. In order to monitor the transient response,three different types of observer designs are introduced in this work together with different aspects of leakage are discussed. Each of the presented observer design methods significantly reduce the required time for leak detection and location. A model is developed on the basis of motion and continuity equations for the single pipeline systems. These equations are derived from fluid transient flow through a cylindrical pipe. The systems are, then, measured by transient flow and pressure measuring devices at two signals point in the beginning and the end of pipeline. The research, devoted primarily to continuous monitoring of the flowrate and pressure that are performed along the pipeline systems. The steady-state analysis technique is verified using simulation via FDI procedure. Presented methods are derived using knowledge from different research fields such as mathematical modelling, systematic inspection and monitoring techhniques. The structure of this thesis is set out in a systematic way so that each of the derived techniques is presented in an individual chapter, which can be read separately.
14
Ananthaganeshan, Kanapathipillai Arunachalam. "Stability and performance of active vibration isolation systems." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273915.
Повний текст джерела
15
Zhang, Ze. "Fault detection and isolation for linear dynamic systems." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9086.
Повний текст джерелаАнотація:
As modern control systems and engineering processes become increasingly more complex and integrated, the consequences of system failures and faults can be disastrous environmentally and economically. This thesis considers the fault detection and isolation (FDI) problem for linear time-invariant (LTI) systems subject to faults, disturbances and model uncertainties. Firstly, a novel on-line approach to the robust FDI problem for linear discrete-time systems is proposed by using input/output measurement analysis over a finite estimation horizon. Upper and lower bounds on the fault signal are computed at each sampling instant so that a fault is detected and isolated when its upper bound is smaller than zero or its lower bound is larger than zero. Moreover, a subsequent-state-estimation technique, together with an estimation horizon update procedure are given to allow the on-line FDI process to be repeated in a moving horizon scheme. Secondly, an optimal solution to theH−/H∞ fault detection (FD) problem is given for linear time-invariant systems subject to faults, disturbances and model uncertainties by using an observer-based approach. A new performance index is developed to capture both fault detection and disturbance rejection requirements which is particularly suitable for handling model uncertainties. A class of optimal solutions to the problem is then given in the form of simple linear matrix inequalities (LMI) with two degrees of freedom. By appropriately choosing these degrees of freedom, fault isolation can also be achieved. Thirdly, in order to improve the FD performance and remove restrictive rank assumptions, routinely made in the literature, observer-based FD problems are investigated at a single frequency and over a finite frequency range, respectively. An optimal solution is derived such that, at a given frequency, the static observer generates a residual signal which minimizes the sensitivity of the residual to disturbances while maintaining a minimum level of sensitivity to faults. Then, an initial investigation is carried out for the FD problem over a finite frequency range. A solution is derived in the form of an LMI optimization by using the generalized KYP lemma followed by a linearization procedure. Conditions under which this solution is optimal are also derived. Fully worked out numerical examples, mostly from the literature, are given to illustrate the effectiveness of all the proposed schemes.
16
Selhammer, Anders. "Probabilistic Fault Isolation in Embedded Systems Using Prior Knowledge of the System." Thesis, KTH, Reglerteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105881.
Повний текст джерелаАнотація:
Nowadays truck engines are controlled by an embedded control system which is a specially designed computer system. It is important that the embedded system is robust against possible faults that could appear when driving the vehicle since faults may cause the vehicle to stop unintended or even worse, crash. To prevent this tests in the system are designed to detect faults and further isolate the faulty behaviors for components. After the isolation fault tolerant control software is used to control the engine in the presence of the faults until the faults have been attended to by a mechanic. In this thesis an application of a probabilistic isolation method that ranks possible faults on their likeliness is presented. The method uses a Bayesian approach for the probability computations based on prior knowledge for ranking the faults in order to improve the result. The probabilistic isolation method is analyzed to show how the isolation performs and how the isolation differs when changing different parameters for the isolation such as test sensitivities and prior knowledge. Different solutions for problems that appear due to different circumstances are also described and evaluated. The solutions handle cases such as limited RAM and execution time, multiple faults and incomplete observations. The result shows a good performance for the probabilistic isolation method and the different solutions. However the method still needs further developments in order to achieve adequate trust for an implementation in vehicles. Future work is proposed and should include further improvements in the isolation of multiple faults.
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Cheng, Luwei, and 程芦伟. "Network performance isolation for virtual machines." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47753183.
Повний текст джерелаАнотація:
Cloud computing is a new computing paradigm that aims to transform computing
services into a utility, just as providing electricity in a “pay-as-you-go”
manner. Data centers are increasingly adopting virtualization technology for the
purpose of server consolidation, flexible resource management and better fault
tolerance. Virtualization-based cloud services host networked applications in virtual
machines (VMs), with each VM provided the desired amount of resources
using resource isolation mechanisms.
Effective network performance isolation is fundamental to data centers, which
offers significant benefit of performance predictability for applications. This research
is application-driven. We study how network performance isolation can be
achieved for latency-sensitive cloud applications. For media streaming applications,
network performance isolation means both predicable network bandwidth
and low-jittered network latency. The current resource sharing methods for VMs
mainly focus on resource proportional share, whereas ignore the fact that I/O latency
in VM-hosted platforms is mostly related to resource provisioning rate. The
resource isolation with only quantitative promise does not sufficiently guarantee
performance isolation. Even the VM is allocated with adequate resources such as
CPU time and network bandwidth, problems such as network jitter (variation in
packet delays) can still happen if the resources are provisioned at inappropriate
moments. So in order to achieve performance isolation, the problem is not only
how many/much resources each VM gets, but more importantly whether the resources are provisioned in a timely manner. How to guarantee both requirements
to be achieved in resource allocation is challenging.
This thesis systematically analyzes the causes of unpredictable network latency
in VM-hosted platforms, with both technical discussion and experimental
illustration. We identify that the varied network latency is jointly caused by
VMM CPU scheduler and network traffic shaper, and then address the problem
in these two parts. In our solutions, we consider the design goals of resource
provisioning rate and resource proportionality as two orthogonal dimensions. In
the hypervisor, a proportional share CPU scheduler with soft real-time support
is proposed to guarantee predictable scheduling delay; in network traffic shaper,
we introduce the concept of smooth window to smooth packet delay and apply
closed-loop feedback control to maintain network bandwidth consumption.
The solutions are implemented in Xen 4.1.0 and Linux 2.6.32.13, which are
both the latest versions when this research was conducted. Extensive experiments
have been carried out using both real-life applications and low-level benchmarks.
Testing results show that the proposed solutions can effectively guarantee network
performance isolation, by achieving both predefined network bandwidth and low-jittered
network latency.published_or_final_version
Computer Science
Master
Master of Philosophy
18
Kline, Paul A. "Fault detection and isolation for integrated navigation systems using the global positioning system." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183731476.
Повний текст джерела
19
Thurén, Mårten. "Fault Isolation By Manifold Learning." Thesis, Linköping University, Vehicular Systems, 1985. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57547.
Повний текст джерелаАнотація:
This thesis investigates the possibility of improving black box fault diagnosis by a process called manifold learning, which simply stated is a way of finding patterns in recorded sensor data. The idea is that there is more information in the data than is exploited when using simple classification algorithms such as k-Nearest Neighbor and Support Vector Machines, and that this additional information can be found by using manifold learning methods. To test the idea of using manifold learning, data from two different fault diagnosis scenarios is used: A Scania truck engine and an electrical system called Adapt. Two linear and one non-linear manifold learning methods are used: Principal Component Analysis and Linear Discriminant Analysis (linear) and Laplacian Eigenmaps (non-linear).Some improvements are achieved given certain conditions on the diagnosis scenarios. The improvements for different methods correspond to the systems in which they are achieved in terms of linearity. The positive results for the relatively linear electrical system are achieved mainly by the linear methods Principal Component Analysis and Linear Discriminant Analysis and the positive results for the non-linear Scania system are achieved by the non-linear method Laplacian Eigenmaps.The results for scenarios without these special conditions are not improved however, and it is uncertain wether the improvements in special condition scenarios are due to gained information or to the nature of the cases themselves.
20
Cornell, Axel. "Probabilistic Fault Isolation in Embedded Systems Using Training Data." Thesis, KTH, Reglerteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105874.
Повний текст джерелаАнотація:
In the heavy vehicle industry customers, laws and increasingly complex processes demand methods of supervising every aspect of a truck. Fault isolation systems are introduced to do just that. In order to assure a sustainable development new types of isolation systems are investigated to substitute the consistency based isolation systems of today. In this thesis an application of a probabilistic isolation method that ranks possible faults on their likeliness of being a fault in the process is implemented and evaluated as a possible future replacement of today's system. This method bases the isolation on training data collected from measurements on the process and observation of the process. The probabilistic isolation method is evaluated on hos it performs under different circumstances such as the effort of different amounts of training data and how well it performs if the tests and observations of the process are of varying quality. Solution to several problems that arise when this method is implemented are also investigated such as how the system handles cases where several faults occur at the same time, what happens if there are missing data in the observations of the system and how to solve problems that involve execution times which is important in embedded systems. The results that are derived show that this probabilistic isolation system performs well on the process as it is today and that this is a good substitute when developing for future processes. There is however a need for further development of the system such as improved isolation when there are several faults present in the process and questions on how to collect and store the training data still remain to be answered. A full scale implement would allow for better comparison with the current system and give more information on runtime and storage problems.
21
Hill, K. E. "The utility of ring springs in seismic isolation systems." Thesis, University of Canterbury. Mechanical Engineering, 1995. http://hdl.handle.net/10092/7923.
Повний текст джерелаАнотація:
Ring springs are frictional devices consisting of inner and outer ring elements assembled to form a spring stack. External load applied to the spring produces sliding action across mating ring interfaces. Large amounts of energy, as much as 60-70% of the total cycle energy, may be absorbed in overcoming frictional forces.
This thesis details the characteristics and dynamic behaviour of ring spring systems and describes the design and testing of a seismic isolation system that uses ring springs.
Initially the characteristics and fundamental dynamic behaviour of single-degree-of-freedom mass/ring spring systems are studied. This study uses a model based upon the non-linear force/deflection characteristics of the ring spring. A prototype ring spring cartridge that enables dynamic inputs to be applied to a ring spring was then designed and subjected to short duration shock excitation. Experimental results are compared with those given by computer simulation and are seen to be in good agreement.
Ring springs have been identified as suitable devices for use in earthquake-resistant structures. A particularly attractive candidate for use of ring springs is in protecting columnar structures during earthquakes. To enable further study, a pivotal rocking seismic isolation system was developed. So that computational analyses of these systems could be undertaken, the ring spring model has been incorporated within the computer program RUAUMOKO. Dynamic analyses using RUAUMOKO show that pivotal rocking isolation systems can significantly reduce structural loads during short period type earthquakes.
Subsequently, a pivotal rocking seismic isolation system was designed and manufactured. Shaker table tests were then carried out on the rocking system for a range of earthquake inputs. The experimental results show that for columnar structures with fundamental periods in the range of dominant spectral accelerations, structural loads can be significantly reduced during short period type earthquakes. Experimental results compare well with those given by computer simulation, thus confirming the effectiveness of the isolation system.
The work outlined in this thesis has established a basis from which further research can be undertaken. The pivotal rocking seismic isolation system developed has potential application to protecting a wide range of columnar structures during short period type earthquakes.
22
Liu, Y. "Fault detection and isolation for wind turbine dynamic systems." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8524/.
Повний текст джерелаАнотація:
This work presents two fault detection and isolation (FDI) approaches for wind turbine systems (WTS). Firstly, a non-linear mathematical model for wind turbine (WT) dynamics is developed. Based on the developed WTS mathematical model, a robust fault detection observer is designed to estimate system faults, so as to generate residuals. The observer is designed to be robust to system disturbance and sensitive to system faults. A WT blade pitch system fault, a drive-train system gearbox fault and three sensor faults are simulated to the nominal system model, and the designed observer is then to detect these faults when the system is subjected to disturbance. The simulation results showed that the simulated faults are successfully detected. In addition, a neural network (NN) method is proposed for WTS fault detection and isolation. Two radial basis function (RBF) networks are employed in this method. The first NN is used to generate the residual from system input/output data. A second NN is used as a classifier to isolate the faults. The classifier is trained to achieve the following target: the output are all “0”s for no fault case; while the output is “1” if the corresponding fault occurs. The performance of the developed neural network FDI method was evaluated using the simulated three sensor faults. The simulation results demonstrated these faults are successfully detected and isolated by the NN classifier.
23
Rensen, Elena Ilka. "Isolation and characterization of hyperthermophilic archaeal virus-host systems." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066652.
Повний текст джерелаАнотація:
Les virus infectant les archées présentent des morphotypes inhabituels et des génomes extrêmement divers. Leur isolation a permis de développer nos connaissances sur la diversité de la virosphère et demeure une piste de recherche primordiale. Durant ma thèse, j’ai isolé et caractérisé de nouveaux virus d'archées et étudié les interactions virus-hôte dans un système modèle bien établi. Des cultures d'enrichissement et des analyses bioinformatiques nous ont permis de décrire de nouveaux virus de crénarchées hyperthermophiles infectant les espèces du genre Pyrobaculum et ainsi de mieux comprendre la diversité architecturale des virus filamenteux. De plus, un provirus a été identifié chez P. oguniense et l’étude de sa réplication a révélé par microscopie électronique des nanostructures pyramidales à la surface des cellules ressemblant à des structures connues de sortie des virions chez des virus de crénarchées. Deux études de protéomique nous ont fourni un aperçu de la dynamique du protéome de Sulfolobus islandicus : l’analyse du protéome de cellules de S. islandicus non infectées a révélé de nombreuses modifications post-traductionnelles, et l’analyse de la régulation des protéines dans des cellules de S. islandicus infectées par le virus SIRV2 a révélé 136 protéines de l'hôte présentant une régulation temporelle significative. L’analyse structurale de SIRV2 a permis d'étudier la résistance des virus crénarchées à des conditions extrêmes et a révélé pour la première fois que la forme A de l'ADN est biologiquement pertinente. Ces résultats ont contribué au développement des connaissances sur la diversité de la virosphère et sur l'évolution des virus d'archéesViruses infecting Archaea display unusual morphotypes and highly diverse genomes. Several virus-host systems have emerged enabling the detailed characterization of virus-host interplay in archaea. However, isolation of new archaeal viruses proved to be instrumental for expanding the knowledge on the diversity of the Earth’s virosphere. Therefore, I have focused on two major lines of research: isolation of new archaeal viruses and characterization of the virus-host interactions in a well-established model system. A new Pyrobaculum virus with a unique architecture among DNA viruses was described, expanding our knowledge on the diversity of architectural solutions explored by filamentous viruses. Furthermore, attempts to trigger the replication of a provirus in P. oguninese led to the development of six-fold pyramidal nanostructures on the cell surface, resembling known virion egress structures of archeal viruses. Finally, I focused on the interplay between Sulfolobus islandicus and the rod-shaped virus SIRV2. Two proteomic studies yielded insights into the dynamics and posttranslational modifications (PTMs) of the Sulfolobus proteome. Sulfolobus proteins were found to carry a high degree of PTMs on functionally diverse proteins. The global analysis of the regulation of viral and host proteins in SIRV2-infected S. islandicus cells yielded insights the temporal regulation of host and virus proteins. Structural studies on SIRV2 virion have resulted in the first ever description of A-form DNA being a biologically relevant form of DNA. Together, these results contribute to the knowledge on the diversity of the extant virosphere, and the biology and evolution of archaeal viruses
24
Akad, Osman Eyup 1958. "Coordination and isolation of faults on power distribution systems." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277965.
Повний текст джерелаАнотація:
Faults on power distribution systems can be prevented quickly and reliably by using solid-state devices to coordinate the optimum functioning and operation of the distribution system. This thesis describes specific systems and circuits designed for this purpose. Some parts employed in the isolation of faults are: sensors, quadrature amplitude modulators, fiber optic cables, programmable logic controllers, generators, band pass filters and silicon controlled rectifiers. Design information and test data are presented.
25
Midéus, Gustav, and Chavez Antonio Morales. "RISC-V Thread Isolation : Using Zephyr RTOS." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279100.
Повний текст джерелаАнотація:
Many embedded systems lack a memory management unit (MMU) and thus often also lack protection of memory. This causes these systems to be less robust since the operating system (OS), processes, and threads are no longer isolated from each other. This is also a potential security issue and with the number of embedded systems rapidly increasing as a result of the rise of Internet of things (IoT), vulnerabilities like this could become a major problem. However, with a recent update to the RISC-V processor architecture, a possibility to isolate regions of memory without an MMU was introduced. This study aims to identify problems and possibilities of implementing such memory protection with RISC-V. Based on a study of literature and documentation on memory protection and the RISC-V architecture, a prototype was designed and implemented to determine potential problems and evaluate performance in terms of execution time and memory cost. The developed prototype showed aworking implementation of memory protection for the memory regions with RISC-V. The evaluation of the prototype demonstrated an increase in context switch execution time and memory usage. The results indicate that the implemented memory protection comes with an increased cost in performance with a constant factor and a small memory overhead. Therefore, it is recommended that implementations that wish to implement memory protection with RISC-V on smaller embedded systems where time and memory may be crucial takes the overhead in consideration. Further research and testing is needed to identify optimizations that could improve the performance as well as discover security flaws.Många inbyggda system saknar en enhet för minneshantering (s.k. MMU) och saknar därför oftast minnesskydd. Detta leder till att dessa system blir mindre robusta eftersom operativsystemet, processer och trådar inte längre är isolerade från varandra. Detta är också en säkerhetsbrist och med antalet inbyggda system som snabbt ökar på grund av tillväxten av Internet of things (IoT), så kan sårbarheter som denna bli ett stort problem. Med en nyligen introducerad uppdatering av RISC-Vprocessor arkitekturen, så introducerades en möjlighet till att isolera minne utan hjälp av en MMU. Denna studie syftar till att identifiera problem och möjligheter av att implementera sådant minneskydd med RISC-V. Baserat på en studie av litteratur och dokumentation om minnesskydd och RISC-V arkitekturen designades och implementerades en prototyp för att hjälpa till att fastställa problem och möjligheter samt göra en utvärdering med avseende på prestanda- och minneskostnader. Den utvecklade prototypen visade en fungerande implementering av minneskydd för minnesregioner med RISC-V. Utvärderingen av prototypen visade en ökad exekveringstid för kontextbyten och ökad minnesanvändning. Resultaten indikerar att det implementerade minneskyddet kommer med en ökad kostnad i prestanda med en konstant faktor och en liten omkostnad i minne. Därför rekommenderas att implementeringar som vill implementera minneskydd med RISC-V på mindre inbyggda system där tid och minne kan vara avgörande tar hänsyn till omkostnaderna. Ytterligare studier och tester behövs för att identifiera optimeringar som kan förbättra prestandan och upptäcka säkerhetsbrister.
26
Rowell, Corbett Ray. "Mobile device antenna design & isolation technologies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50533897.
Повний текст джерелаАнотація:
Mobile device antenna design and isolation technologies are thoroughly investigated in this thesis. The antenna design parameters for mobile devices are quantified using practical restraints by analyzing almost 60 mobile handsets and the effect of materials, human tissue, manufacturing, and antenna type/placement on antenna design and then mapped into Wheeler-space that correlates the spherical wave modes with the antenna performance.
The isolation technologies with mutual coupling anti-resonances are unified by a single performance parameter to distinguish them from the more traditional isolation technologies. This unifying performance parameter is the group delay between two antennas where high group delay indicates the presence of a bandstop filter in the form of either a PCB or an antenna modification. This thesis analyzes both PCB and antenna modifications with high group-delay and demonstrates these types of antennas can be placed in close proximity without affecting other performance parameters. It is also shown that both the PCB and antenna modifications contain two isolation methods where each isolation method is a mirror complement of the other method.
Some antenna geometries can also increase the mutual coupling in order to improve the antenna performance using a phenomena called over-coupling. These over-coupled antenna systems can result in lower SAR for the cellular antennas and decreased array sizes for NFC/RFID/wireless-power antennas, resulting in better performance of antennas inside mobile devices.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
27
Sonti, Niharika. "A Unified Method for Detecting and Isolating Process Faults and Sensor Faults in Nonlinear Systems." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1292763603.
Повний текст джерела
28
Lawesson, Dan. "Towards Behavioral Model Fault Isolation for Object Oriented Control Systems." Licentiate thesis, Linköping University, Linköping University, TCSLAB - Theoretical Computer Science Laboratory, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5734.
Повний текст джерелаАнотація:
We use a system model expressed in a subset of the Unified Modeling Language to perform fault isolation in large object oriented control systems. Due to the severity of the failures considered and the safety critical nature of the system we cannot perform fault isolation online. Thus, we perform post mortem fault isolation which has implications in terms of the information available; the temporal order in the error log can not be trusted. In our previous work we have used a structural model for fault isolation. In this thesis we provide a formal framework and a prototype implementation of an approach taking benefit of a behavioral model. This gives opportunities to perform more sophisticated reasoning at the cost of a more detailed system model. We use a model-checker to reason about causal dependencies among the events of the modeled system. The model-checker performs reasoning about temporal dependencies among the events in the system model and the scenario at hand, allowing for conclusions about the causal relation between the events of the scenario. This knowledge can then be transferred to the corresponding fault in the system, allowing us to pinpoint the cause of a system failure among a set of potential causes.
Report code: LiU-Tek-Lic-2000:59.
29
Alrowaie, Feras A. "Fault isolation and alarm design in non-linear stochastic systems." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52010.
Повний текст джерелаАнотація:
In this project, first we propose a novel model-based algorithm for fault detection and isolation (FDI) in stochastic non-linear systems. The algorithm is established based on parameter estimation by monitoring any changes in the behaviour of the process and identifying the faulty model using a bank of particle filters running in parallel with the process model. The particle filters are used to generate a sequence of hidden states, which are then used in a log-likelihood ratio to detect and isolate the faults. The newly developed scheme is demonstrated through implementation in two highly non-linear case studies. Finally, the effectiveness and robustness of the proposed diagnostic algorithm are illustrated by comparing the results obtained by applying the algorithm to the multi-unit chemical reactor system using other FDI techniques, based on EKF and UKF state estimators.
Second, we propose an approach based on particle filter algorithm to isolate actuator
and sensor faults in stochastic non-linear and non-Gaussian systems. The proposed FDI approach is based on a state estimation approach using a general observer scheme (GOS), whereby a bank of particle filters is used to generate a set of residuals, each sensitive to all but one fault. The faults are then isolated by monitoring the behaviour of the residuals where the residuals of the faulty sensors or actuators behave differently than the faultless residuals. The approach is demonstrated through implementing two highly non-linear case studies.
Non-linear stochastic systems pose two important challenges for designing alarms : (1) measurements are not necessarily Gaussian distributed and (2) measurements are correlated - in particular, for closed-loop systems. We therefore present an algorithm for designing alarms based on delay timers and deadband techniques for such systems, with unknown and known models. In the case of unknown models, our approach is based on Monte Carlo simulations. In the case of known models, it makes use of a probability density function approximation algorithm called particle filtering. The alarm design algorithm is illustrated through two simulation examples. We show that the proposed alarm design is effective in detecting the fault, even though the measurements are non-Gaussian.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
30
Han, Mengyu. "Application of Base Isolation Systems to Reinforced Concrete Frame Buildings." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35722.
Повний текст джерелаАнотація:
Seismic isolation systems are widely used to protect reinforced concrete (RC) structures against the effects of strong ground motions. After a magnitude 6.6 earthquake, the outpatient building of Lushan People’s hospital in China remained in good condition due to the seismic isolation technology, while the non-isolated older outpatient building nearby experienced major damage. The building provides a good opportunity to study and assess the contribution of isolation systems to seismic performance of RC structures. In the current research project, the isolated outpatient building was modelled and analyzed using computer software SAP2000. The post-yield behaviour of the structure was modelled by assigning multi-linear plastic links to frame objects. The rubber isolators were represented by rubber isolator link elements, assigned as a single joint element between the ground and the superstructure. The isolated structure was subjected to four earthquake records with increasing intensity. The performances of the isolated structure were compared with those of the fixed-base structures in terms of lateral inter-storey drifts, peak absolute floor accelerations, and residual drifts. The laminated rubber bearings, the high damping isolation devices, composed of rubber bearings and viscous dampers, and the hybrid isolation system of rubber bearings and friction pendulum bearings were analysed. The effectiveness of the three base isolation systems considered in enhancing structural performance was investigated. The results show the level of improvement attained in seismic response by each system. They also illustrate that the rubber bearings coupled with friction pendulum bearings produce the best drift control without causing excessive horizontal displacements at the base level and without adversely affecting floor accelerations.
31
Lawesson, Dan. "Towards behavioral model fault isolation for object oriented control systems /." Linköping : Univ, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5734.
Повний текст джерела
32
Mori, Atsushi. "Investigation of the behaviour of seismic isolation systems for bridges." Thesis, University of Canterbury. Department of Civil Engineering, 1993. http://hdl.handle.net/10092/2455.
Повний текст джерелаАнотація:
The thesis is concerned with the experimental and analytical investigations into the behaviour of
laminated elastomeric and lead-rubber bearings as seismic isolation bearings for bridges.
Seismic isolation as a seismic design option has become popular over the past decade. During last
several years, Japan, Italy and the U.S.A. have been making great progress following the great
contribution of New Zealand in this area. Despite new developments in seismic isolation systems, the
New Zealand lead-rubber bearings (LRB) still lead with their reputation for reliable performance. The
design methods for lead-rubber bearings applied for both bridges and buildings are provided in each of
these countries but with differences to allow for variations in codes and design applications. However
the basic concepts of these design methods are similar and are partially based on empirical
backgrounds.
Acknowledging the above status, the experimental and analytical investigations into the lead-rubber
and laminated elastomeric bridge bearings were carried out under compression, shear and rotation
loading states. A maximum bearing compressive strain of about 6% was reached in the compression
tests. In the shear tests, a maximum bearing shear strain of 200% was reached in the load-deflection
response and the lead-rubber bearings showed almost the same shear stiffness as the elastomeric
bearings after yield of the lead. The rotation tests were performed over the limitations stipulated in the
current design codes showing a constant linear stiffness independent of the axial load levels on the
bearings. The analytical investigation using the finite element method indicated that the steel shims in
the bearings might exceed the yield point somewhere between 100% and 150% bearing shear stains,
The shear strains in the rubber due to different types of loading calculated by the existing code
relationships, and which are usually the governing factor for the bearing design, were not in reasonable
agreement with the analytically obtained values except under compression. The relationships for
predicting load-deflection response of the bearings used in the bearing design methods always gave
excessive values when compared with the experimentally and analytically obtained values.
Based on the findings in the experimental and analytical work, several recommendations for the design
of seismic isolation bridge bearings are presented. Moreover, the dynamic response analysis for
bridges incorporating seismic isolation systems is carried out under different seismic excitations to
confirm the benefits of the seismic isolation systems. As a consequence, for continuous multi-span
long bridges the benefits due to seismic isolation in terms of reducing member forces in the bridge and
keeping the dynamic behaviour of bridge piers uniform regardless of travelling velocities of the
seismic wave are greater when compared with those for standard bridge structures.
33
Krishnaswami, Vasanth. "Model based fault detection and isolation in nonlinear dynamic systems /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794218232319.
Повний текст джерела
34
Astolfi, Giacomo. "Data-based design of fault detection and isolation (FDI) systems." Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242719.
Повний текст джерелаАнотація:
Lo scopo di questa tesi è la presentazione di un innovativo sistema di Fault Detection e Isolation (FDI) basato su un approccio data-driven. La scelta di utilizzare un approccio data-based è stata dettata dal fatto che, molto spesso, in applicazioni industriali, modelli dinamici del processo non sono disponibili o non sono particolarmente utili per scopi diagnostici.
L’innovativo sistema FDI proposto combina le seguenti metodologie: Principal Component Analysis (PCA), Cluster Analysis e Pattern Recognition.
Il risultato è quello che l’autore ha definito Fuzzy Fault Classifier (FFC). La combinazione delle tre tecniche sopracitate permette di rilevare ed isolare automaticamente guasti singoli e guasti multipli. Questo sistema è stato altresì arricchito dall’uso di soglie adattative la cui progettazione si è inspirata a degli schemi classici proposti in letteratura; l’apporto innovativo è stato quello di identificare alcuni parametri incogniti attraverso un approccio basato sull’uso dell’analisi spettrale dei segnali di ingresso.
Per risolvere il cruciale problema della scelta delle Componenti Principali nella PCA, è stato presentato un nuovo metodo basato sul noto test statistico ANOVA (ANalysis Of VAriance); tale metodologia è stata confrontata con altri approcci ed i suoi benefici possono essere valutati.
Il sistema FDI descritto è stato testato per valutare le capacità di identificazione e di isolamento dei guasti singoli e multipli, assieme ai principali gusti di processo, dei seguenti processi reali: Compressore Centrifugo Multistadio e Unmanned Surface Vehicle (USV).
La bontà e l'efficienza del sistema FDI possono essere apprezzate valutando i risultati ottenuti. Essi confermano la capacità del sistema in termini di individuazione ed isolamento dei guasti ed inoltre, vista la sua caratteristica data-based, la possibilità di estenderne l'uso ad altri processi. L'unico requisito è la presenza di misure affidabili delle principali grandezze di processo.The objective of this research is to propose a Fault Detection and Isolation (FDI) system based on data-driven approach. The choice of approaching the fault diagnosis problem with a model-free methodology rather than a model-based approach was motivated by the fact that in some particular applications dynamic models are not available or not appropriate for fault detection and isolation purposes. The proposed innovative FDI system combines Principal Component Analysis (PCA), Cluster Analysis and Pattern Recognition technique: the result is the so called Fuzzy Faults Classifier (FFC). The combination of these techniques allows to automatically detect and isolate single and multiple faults and allow to overcome the growth of the complexity in the analysis of process faults that typically involve many variables. The research also proposes the use of the adaptive thresholds: the thresholds scheme follows a classical structure proposed in literature but the parameters used on it have been computed by an innovative approach based on the spectral analysis of the process inputs. The main task of PCA, i.e. the choice of the Principal Component retained in the model, has been accomplished by a new method, based on the statistical test ANOVA (ANalysis Of VAriance) and a comparison with other criteria present in literature has been made. The FDI system has been tested for the detection and the isolation of single and multiple faults as well as process faults of two particular systems: Multishaft Centrifugal Compressor and Unmanned Surface Vehicle (USV). The goodness and the efficiency of the proposed Fault Detection and Isolation system can be appreciate by the inspection of the results obtained in the real process. The results confirm the ability of the system in terms of fault detection and fault isolation and the possibility to extend its use to different real process. The only requirement is the presence of good measurement concerning the main process variables.
35
Lombardo, Pierpaolo. "Fully Integrated Data and Power Transfer Systems with Galvanic Isolation." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3943.
Повний текст джерелаАнотація:
My principal activity was focused on the design of galvanically isolated integrated systems as a part of a research project at the RF ADC by exploiting STMicroelectronics technology platforms providing on chip galvanic isolation. This technology was previously addressed to the implementation of isolated data transfer and it is currently used for mass production. In this context, the principal purpose of my work was the investigation on a fully integrated dc-dc power converter with half-duplex data communications providing on chip galvanic isolation in silicon technologies. This research is mainly interested in increasing the level of integration for the next generation of power converters with data transfer and several other applications requiring galvanic isolation. Autonomous sensors and/or control circuits, typically require a few tens of Mbps for data communication and an output power from tens to hundreds of mW. In this context, fully integrated interfaces can provide several advantages, including higher reliability, lower PCB area, lower system complexity and lower costs, especially if only silicon technology is exploited.
36
Do, Van Long. "Sequential detection and isolation of cyber-physical attacks on SCADA systems." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0032/document.
Повний текст джерелаАнотація:
Cette thèse s’inscrit dans le cadre du projet « SCALA » financé par l’ANR à travers le programme ANR-11-SECU-0005. Son objectif consiste à surveiller des systèmes de contrôle et d’acquisition de données (SCADA) contre des attaques cyber-physiques. Il s'agit de résoudre un problème de détection-localisation séquentielle de signaux transitoires dans des systèmes stochastiques et dynamiques en présence d'états inconnus et de bruits aléatoires. La solution proposée s'appuie sur une approche par redondance analytique composée de deux étapes : la génération de résidus, puis leur évaluation. Les résidus sont générés de deux façons distinctes, avec le filtre de Kalman ou par projection sur l’espace de parité. Ils sont ensuite évalués par des méthodes d’analyse séquentielle de rupture selon de nouveaux critères d’optimalité adaptés à la surveillance des systèmes à sécurité critique. Il s'agit donc de minimiser la pire probabilité de détection manquée sous la contrainte de niveaux acceptables pour la pire probabilité de fausse alarme et la pire probabilité de fausse localisation. Pour la tâche de détection, le problème d’optimisation est résolu dans deux cas : les paramètres du signal transitoire sont complètement connus ou seulement partiellement connus. Les propriétés statistiques des tests sous-optimaux obtenus sont analysées. Des résultats préliminaires pour la tâche de localisation sont également proposés. Les algorithmes développés sont appliqués à la détection et à la localisation d'actes malveillants dans un réseau d’eau potableThis PhD thesis is registered in the framework of the project “SCALA” which received financial support through the program ANR-11-SECU-0005. Its ultimate objective involves the on-line monitoring of Supervisory Control And Data Acquisition (SCADA) systems against cyber-physical attacks. The problem is formulated as the sequential detection and isolation of transient signals in stochastic-dynamical systems in the presence of unknown system states and random noises. It is solved by using the analytical redundancy approach consisting of two steps: residual generation and residual evaluation. The residuals are firstly generated by both Kalman filter and parity space approaches. They are then evaluated by using sequential analysis techniques taking into account certain criteria of optimality. However, these classical criteria are not adequate for the surveillance of safety-critical infrastructures. For such applications, it is suggested to minimize the worst-case probability of missed detection subject to acceptable levels on the worst-case probability of false alarm and false isolation. For the detection task, the optimization problem is formulated and solved in both scenarios: exactly and partially known parameters. The sub-optimal tests are obtained and their statistical properties are investigated. Preliminary results for the isolation task are also obtained. The proposed algorithms are applied to the detection and isolation of malicious attacks on a simple SCADA water network
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Cormier, Roger. "Isolation of concurrent faults in sensors and actuators in control systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ46290.pdf.
Повний текст джерела
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Mazars, Emmanuel Francis Marie. "Robust fault detection and isolation for linear time-invariant dynamic systems." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437363.
Повний текст джерела
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Widener, Christopher. "Fault isolation in power electronic based distribution systems without circuit breakers." Thesis, The Florida State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1559659.
Повний текст джерелаАнотація:
In the Future Renewable Electric Energy Distribution and Management (FREEDM) system, solid state Fault Isolation Devices (FIDs) are used to react to signals from a fault detection and location system to isolate faulted sections of a fault current limited power electronics based 12.47 kV distribution system. They accomplish this by interrupting fault currents, which in the FREEDM system are limited by Solid State Transformers (SST). However, as was expected, due to its silicon transistor technology, the developed FID prototype demonstrated rather high on-state losses during its operation. Therefore, it is necessary to perform comparison studies with alternative methods of sectionalizing faulted parts of the FREEDM grid. To respond to this need, a system study has been undertaken to explore an alternative fault isolation strategy, which instead of allowing fault currents to remain in the system uses the abilities of the SSTs to completely turn off fault currents. Once this turn-off has been accomplished, regular mechanical disconnects isolate the faulted section and the system is reenergized. Behavioral 3-phase PSCAD average-value SST models have been developed and are used in a representative model of the FREEDM Green Hub to demonstrate how this strategy would operate. Simulation data is presented that shows how the SSTs would react to fault situations, remove fault currents, and reenergize the system. The characteristic example system was constructed and parameterized allowing for sensitivity analyses to be performed. A comparison is made with the fault-current-breaking FID method of fault isolation currently in use and it is discussed how the presented approach can be used to evaluate future FREEDM fault isolation strategies.
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Lavallee, Phillip M. (Phillip Michael). "Applications of force actuators and variable stiffness systems with base isolation." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43881.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.Includes bibliographical references (p. 77-78).
Recent developments have occurred that limit the effectiveness of conventional strength-based structural design. First, there has been a trend towards designing more flexible structures that require increased emphasis on structural motion and serviceability. Next, motion has become more important for the design of new facilities that house very sensitive manufacturing and operating equipment. This equipment can only operate properly under extremely low movement conditions. Third, advances in material science and engineering have led to developing materials with significantly increased strengths, but the stiffness of these materials have not increased at the same rate. Motion parameters control the design for these high-strength materials. Finally, recent earthquake responses have shown that repair costs from structural damage due to inelastic deformation that was much greater than anticipated. This has led to a trend in reducing the reliance on inelastic deformation in the structure to dissipate energy, and designing control of the response with other energy dissipation and absorption devices. Motion-based design is more effective to address the developments mentioned above. To control the motion of civil structures from earthquake excitations, base isolation systems have become more common to uncouple the structure from the ground. Base isolation reduces the lateral stiffness of the bottom floor to allow large movement of the structure as a rigid body for earthquake excitations. For lower service loads such as wind, the lateral stiffness of the isolation bearings is insufficient to prevent the structure from large movement and uplift. Variable stiffness systems have been used to adjust lateral stiffness based on the size of the load experienced.
(cont.) This thesis proposes using force actuators to increase and decrease lateral stiffness by clipping and unclipping horizontal members when the ground acceleration reaches preset threshold limits. When clipped, the structure responds as a conventional strength-based designed structure. When unclipped, the structure responds as a base isolated structure. After an event is complete, the actuators re-clip and the structure is prepared for the next event.
by Phillip M. Lavallee.
M.Eng.
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Maleki, Sepehr. "A geometric approach to fault detection and isolation in multidimensional systems." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/379271/.
Повний текст джерелаАнотація:
In this thesis the problem of fault detection and isolation for two subclasses of multidimensional systems, i.e., 3-D systems and repetitive processes is investigated by extending the geometric approach and notions of input containing conditioned invariants developed and introduced for standard 1-D linear systems to be applicable in multidimensional systems. The problem is investigated by designing an asymptotic observer that asymptotically reconstructs the system state. In case of a failure, the observer continues to reconstruct the state normally, however, the system produces a wrong state resulting in deviation of the system state from the estimated state in the observer. Comparing the magnitude of this deviation against a predefined threshold indicates whether a failure has occurred in the system or not. The fault detection and isolation problem for the aforementioned systems is formulated in a geometric language and necessary and sufficient conditions are developed for the solvability of this problem, and constructive methods to design observers that uniquely can isolate the failure by exploiting the subspaces that the error lies onto. Finally, the efficiency of the developed technique is examined by using examples for each system.
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Fiore, Vincenzo. "Fully integrated systems with on-chip galvanic isolation in silicon technology." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3866.
Повний текст джерелаАнотація:
In this work the investigation on fully integrated systems providing on-chip galvanic isolation is presented, which exploits a silicon technology by STMicroelectronics.
This research is mainly motivated by the higher level of integration that is demanded to the next generation of power converters and general applications featuring galvanic isolation. State-of the art implementations rely on complex post-processed passive devices to implement isolated power transfer within multi-die system in packages.
In this work, two silicon implementations are mainly discussed, i.e. a step-up power transfer system and the ASK data receivers of a data/power transfer system. They achieve up to 980 mW output power with 29.6% efficiency and up to 40 Mbps with 5% modulation index, respectively, thus showing enhanced performance with respect to the state-of-the-art. Each system requires only two silicon chips to implement both galvanic isolation and power transfer, thus achieving the highest possible level of integration for a pure silicon technology.
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Bernabe, Gisbert Jose Maria. "SUPPORTING MULTIPLE ISOLATION LEVELS IN REPLICATED ENVIRONMENTS." Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/36535.
Повний текст джерелаАнотація:
La replicación de bases de datos aporta fiabilidad y escalabilidad aunque hacerlo
de forma transparente no es una tarea sencilla. Una base de datos replicada es
transparente si puede reemplazar a una base de datos centralizada tradicional sin
que sea necesario adaptar el resto de componentes del sistema. La transparencia
en bases de datos replicadas puede obtenerse siempre que (a) la gestión de la
replicación quede totalmente oculta a dichos componentes y (b) se ofrezca la
misma funcionalidad que en una base de datos tradicional.
Para mejorar el rendimiento general del sistema, los gestores de bases de datos
centralizadas actuales permiten ejecutar de forma concurrente transacciones
bajo distintos niveles de aislamiento. Por ejemplo, la especificación del benchmark
TPC-C permite la ejecución de algunas transacciones con niveles de aislamiento
débiles. No obstante, este soporte todavía no está disponible en los
protocolos de replicación. En esta tesis mostramos cómo estos protocolos pueden
ser extendidos para permitir la ejecución de transacciones con distintos niveles
de aislamiento.Bernabe Gisbert, JM. (2014). SUPPORTING MULTIPLE ISOLATION LEVELS IN REPLICATED ENVIRONMENTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36535
TESIS
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Durant, Brian R. "Optimal design of nonlinear shock isolation for large, locally nonlinear structural systems." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA360098.
Повний текст джерелаАнотація:
Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, December 1998."December 1998." Thesis advisor(s): Joshua H. Gordis. Includes bibliographical references (p. 85). Also available online.
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Mok, Hing-tung. "Online fault detection and isolation of nonlinear systems based on neurofuzzy networks." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39794064.
Повний текст джерела
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Mok, Hing-tung, and 莫興東. "Online fault detection and isolation of nonlinear systems based on neurofuzzy networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39794064.
Повний текст джерела
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Dueñas, Osorio Leonardo Augusto 1976. "Optimization of base isolation systems using low-cost bearings and frictional devices." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84275.
Повний текст джерелаАнотація:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Vita.
Includes bibliographical references (leaves 52-53).
by Leonardo Augusto Dueñas Osorio.
M.Eng.
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Behrens, Diogo, Marco Serafini, Sergei Arnautov, Flavio Junqueira, and Christof Fetzer. "Scalable error isolation for distributed systems: modeling, correctness proofs, and additional experiments." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-203622.
Повний текст джерела
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Md, Kamal Mahanijah. "Intelligent fault detection and isolation for proton exchange membrane fuel cell systems." Thesis, Liverpool John Moores University, 2014. http://researchonline.ljmu.ac.uk/4574/.
Повний текст джерелаАнотація:
This work presents a new approach for detecting and isolating faults in nonlinear processes using independent neural network models. In this approach, an independent neural network is used to model the proton exchange membrane fuel cell nonlinear systems using a multi-input multi-output structure. This research proposed the use of radial basis function network and multilayer perceptron network to perform fault detection. After training, the neural network models can give accurate prediction of the system outputs, based on the system inputs. Using the residual generation concept developed in the model-based diagnosis, the difference between the actual and estimated outputs are used as residuals to detect faults. When the magnitude of these residuals exceed a predefined threshold, it is likely that the system is faulty. In order to isolate faults in the system, a second neural network is used to examine features in the residual. A specific feature would correspond to a specific fault. Based on features extracted and classification principles, the second neural network can isolate faults reliably and correctly. The developed method is applied to a benchmark simulation model of the proton exchange membrane fuel cell stacks developed at Michigan University. One component fault, one actuator fault and three sensor faults were simulated on the benchmark model. The simulation results show that the developed approach is able to detect and isolate the faults to a fault size of ±10% of nominal values. These results are promising and indicate the potential of the method to be applied to the real world of fuel cell stacks for dynamic monitoring and reliable operations.
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Behrens, Diogo, Marco Serafini, Sergei Arnautov, Flavio Junqueira, and Christof Fetzer. "Scalable error isolation for distributed systems: modeling, correctness proofs, and additional experiments." Technische Universität Dresden, 2015. https://tud.qucosa.de/id/qucosa%3A29539.
Повний текст джерела