Dissertations / Theses on the topic 'Long Cable'

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.
Includes bibliographical references (leaf 46).
In the design of a structure, one of the most difficult parameter to assess is how the initial condition of a structure will change with time. During its life span, a structure can be subjected to different loads, changes in geometric configuration and even changes in its mechanical properties. Among all factors that can affect the geometrical reconfiguration of a structure (i.e. settlements and overloads) creep is one of the most important given its inevitability and because of its persistent effects (normally estimated as ten thousand days). Due to the effect of creep, a structure tends to amplify its deformation under a given load condition over time, and the final deformation can even reach values five or six time grater than the initial ones. During the design, the fact that deformations grow with time can be a difficult condition especially for highly indeterminate structures like cable stayed bridges where the stresses are related to the geometric configuration of the structure itself. In concrete cable stayed bridges, in fact, the increase in the deformation of the deck and the pylons over time leads to a decrease in the initial tension in the stays with an obvious difficulty in the design phase of the structure. The first chapter of this thesis illustrates and explains one approximate method used to estimate the effect of creep on a concrete structure. The method proposed in this thesis is the "Age-Adjusted Effective Modulus Method". It was chosen among others because it is one of the most commonly used, and because it is highly accessible.
(cont.) In the second chapter, the Age-Adjusted Effective Modulus Method will be used in conjunction with the force method to study non homogeneous, indeterminate structure under the effect of creep. In this chapter a procedure will be introduced that enables the calculation of an initial value of the prestressing force in the stays that elides the effect of creep on tension. Bridge in Maine, USA (M.Eng Project. Alexander Otenti, Andrea Scotti, Richard Unruh III, 2004). The theory exposed in this thesis is a very powerful procedure that permits to simplification of the problem of creep in cable-stayed bridges, with easy calculations and with an iterative procedure.
by Andrea Scotti.
M.Eng.

This study investigates the static behavior and dynamic behavior of the Stonecutters Cable-Stayed Bridge, which is the third longest cable-stayed bridge in the world, when a group of 8 cables is damaged by corrosion. In this thesis, the reduction in cable cross-section area is used to simulate the corrosion level. The corroded cables are divided into 2 groups of 4 cables, arranged in symmetric and asymmetric distributions on both decks. A finite element bridge model was employed to perform the analysis. The validation of the model was established by comparing numerical results to the published results of the bridge. The model was then subjected to gravity load only to check the effects of corrosion level, the distance of the corroded cables and the distribution of the damaged cables on the decks’ deflection and cable stresses change. In the dynamic analysis, the natural frequencies and mode shapes were compared with a reference case with no corrosion-damaged cables. A recorded wind load was applied on the deck to investigate the time-history response of the mid-span in the horizontal, vertical and torsional directions, and of the tower top in the horizontal direction. Moreover, frequency analysis was performed on the time-history response, and coupled motions at certain frequencies were observed. Numerical results as the ones presented in this thesis can complement information gathered from non-destructive testing technology in detecting corrosion-damaged stay-cables in cable-stayed bridges.

The objective of this research is to identify and evaluate factors which may influence the long-term performance of the low voltage aerial bundled cable system erected within the boundaries of the South East Queensland Electricity Board's area of supply. Field inspections of a number of in-service installations were carried out which identified a range of problems relating to the corrosion of bolts and ABC conductor cores when erected in close proximity to surf beaches. The scope of the project was restricted to an investigation related to the ABC system's resistance to corrosion, its limits of electrical and mechanical performance, and the degradation of materials due to exposure to ultraviolet radiation. Abrasion and vibration in the ABC system was not envisaged to be a major factor in limiting the long-term performance of the system. The course of the research identified the major mechanism by which moisture and pollutants are permitted to enter conductor cores at insulation piercing connector sites. The testing program showed that insulation piercing connectors were unable to prevent the ventilation of air in the interstices within the stranded conductor core under the action of air pressure differentials being caused by increases and decreases of cable temperature. The research also showed that the XLPE insulation of the conductors can be damaged when the system is subjected to certain overload and short circuit conditions. A methodology has been developed which can define the mechanical limits of the XLPE insulation by the use of "kneeing curves". This allows a process to be used which will enable an appropriate size of low voltage fuse to be selected for protection of the insulation under overload and short circuit conditions. Photomicrographs of samples of XLPE insulation recovered from inservice applications show that some cable insulation has been manufactured with poor carbon black dispersion, but the degrading effects of ultraviolet radiation have not been determined. A number of conclusions and recommendations can be made as a result of this research which have the potential to significantly improve the long term performance of low voltage aerial bundled cable.

The conflicting demands connected from a side to the crossing of span always longer and from the other to the containment of the environmental impact of the structures set the necessity to critically re-examine the designing aspects that has brought to define the actual standards for the realization of long span cable bridges. In the case of fan-shaped scheme with "H" towers, the analysis of the statical behaviour of such structures through analytical approaches in closed form is currently founded on continuous models where the interaction between the girder and the cables is modeled through the Dischinger's tangent theory, that is through a first order approach in the displacements. In the case of non too long span, such approach allows to model in a satisfactory way the intrinsic non linear behaviour of such structures, connected to the presence of complexes structural elements as cables. On the other hand, when the spans become meaningful, the effects of interaction cable-girder can strongly be influenced by the high geometric non linearity in the behaviour of the cables "almost perpendicular" with respect to the weight force's direction, that is with respect to the forces's direction which act on the deck and therefore on the cables themselves. In this case, the sag effect with respect to the configuration of cable's chord is strong and, also holding valid the hypothesis of small displacements for the girder, the correct modeling of the behaviour of the whole structure has to bring in account the strong non linearity of the mechanical response of such structural elements. Starting from a "quasi-secant" model to describe the behaviour of the single cable, giving a second order approximation both with respect to the stress variation and to the apparent chord-strain one, the cable-girder interaction is modeled through a second order displacement approach able to take into account the finite variation of the cable's chord direction induced by the deformation of the stay-supported deck. In this way a closed-form formulation is obtained which, unlike classical secant model, does not need iterative procedures. Considering then a Eulero-Bernoulli model to describe the bending behaviour of the girder and a De Saint Venant model to decribe the torsional one, a refined continous model of the whole structure able to describe its statical behaviour has been developed. Moreover closed form solutions of the model, developed according to perturbative tecnique and valid under generic load acting on the bridge's deck, are proposed. The proposed results obtained from the present model and the comparisons effected confirm the best correspondence of the proposed approach in relationship to the behaviour attended of the structure, putting in evidence a prevailing truss behaviour of the bridge and the coupled nature of the bending and torsion of the girder, induced by the strong non linearity of the actions of cable-girder interaction.

The finite strip method (FSM) is a very efficient numerical method employed for performing the structural analysis of slender structures, such as cable-stayed bridges; the strip discretization of the model allows for the usage of a lower number of degrees of freedom, in comparison with the finite element method (FEM), while, as it will be discussed in the current research, the results obtained from both methods are in relatively good agreement. Moreover, to address the latest developments in the area of smart construction materials used for long-span bridges, the fiber reinforced polymer (FRP) composites were implemented for the bridge deck modeling, as part of a hybrid composite FRP cable-stayed bridge, and an extend laminate integrated finite strip method (LFSM) was applied for estimating the static structural performance of the hybrid composite FRP long-span cable-stayed bridge under several concentrated and uniformly distributed loadings. The free vibrations analysis was conducted for the Kap Shui Mun Cable-stayed Bridge model, and the natural frequencies were compared with the ones obtained from an FE model of the same bridge. One of the advantages of using the integrated finite strip method is that number of vibration modes, which can be included in the dynamic analysis when the effect of a sweeping sinus and a seismic loading are investigated when a conventional FE analysis would fail to converge. The outcomes of this research will set the stage for the hybrid long-span cable-stayed bridges modeling by the laminate integrated finite strip method (LFSM) which is more efficient and straightforward than the finite element analysis, for performing the static, free vibration, time domain, and frequency domain analyses.

Bridges play an important role as the backbone of a country’s road network system, since they have a major impact on a country’s industrial development. Therefore, a vast amount of public and private capital is invested into bridge construction. For this reason, bridges will continue to be constructed as long as they contribute to both the economic development and the industrial development of a country. Currently, bridges are evolving fast in terms of their size and roles on account of developments inrelevant techniques and the use of advanced computers and information technology (IT). However, bridge monitoring technologies have fallen behind these rapidly advancing bridge construction techniques. Bridge accidents can be directly linked to the indifference of society and slow developments in monitoring systems of the road network system. Consequently, a number of bridge collapse accidents have occurred either directly or indirectly as a result of a lapse in monitoring. These accidents are attributed mainly to construction-oriented policies and the public’s insensitivity to safety. The ultimate goal of the present study is to establish a global navigation satellite system (GNSS)-based bridge health monitoring system (BUMS). The study was implemented under the category of a structuralhealth monitoring (SHM) system. In addition, a variety of experiments were performed and algorithms were applied in the study in order to obtain a more reliable set of results and to achieve safer information delivery and operation of the system. The outcome is the realization of a new' paradigm of a BHMS, which outperforms its present counterpart.

The maximum length of an high voltage underground cable (HV UGC) cable is oftenconstrained by the criterion that the cable cannot have more than 50% reactivepower compensation. If this limit is exceeded the current in the circuit breaker maynot have a zero crossing after energization, which is referred to as the zero missingphenomenon. This is problematic if a fault occur shortly after energization. Inthe past 10 years, different methods have been proposed which would allow greaterreactive power compensation. These methods either prevent the zero missing phenomenon(preventive methods) or provide a way to open the circuit breaker if afault occurs (handling methods).A new 200 km, 220 kV line has been proposed in Iceland referred to as Sprengisandslína.One proposed option is to build it as an OHL-UGC-OHL line as the voltagecriteria is not fulfilled if Sprengisandslína is built as an UGC with a 50% reactivepower compensation. The aim of this thesis is to see whether the zero missing phenomenoncan be avoided by implementing countermeasures - this gives a preliminaryresults whether Sprengisandslína can be built as an UGC. In this thesis the four differentpreventive methods are analyzed with a transient study for Sprengisandslína:(1) Pre-insertion resistor, (2) simultaneous synchronized switching, (3) synchronizedswitching where the cable is energized before the shunt reactor, and (4) synchronizedswitching where the shunt reactor is energized before the cable.Preliminary steady state studies were performed to determine the minimum numberof shunt reactors needed to fulfill the voltage criteria. The results showed thatthe minimum number needed were three assuming they are all of equal size locatedevenly along the cable (one at each end and one in the middle). Additionally, it isnecessary to see whether the generators would become underexcited if the cable isiiienergized with 100% reactive power compensation as it can reduce the lifetime ofthe generators. The results showed that the generators did not become underexcited.The countermeasure of synchronized switching where the shunt reactor is energizedbefore the cable and the countermeasure of simultaneous synchronized switchingwere shown to eliminate the zero-missing phenomenon when the cable was energizedwith 100% reactive power compensation. Synchronized switching where theshunt reactor is energized before the cable was seen to have lower switching overvoltages,21% higher than the nominal value, and the lower inrush current of 2.38kA. However, the method of simultaneous synchronized switching is cheaper andthe switching overvoltages and inrush current were within an acceptable margin(switching overvoltages were 35:9% higher than the nominal value and the inrushcurrent was 4.01 kA).The results of the study indicate that Sprengisandslína can be energized as an UGCwith 100% reactive power compensation if either the countermeasure of simultaneoussynchronized switching or synchronized switching where the shunt reactor isenergized before the cable are used. However, a detailed frequency study must beperformed before either of the countermeasures can be recommended.
Högsta längden på en högspänning underjordisk kabel begränsas ofta av de kriteriersom kabeln inte kan ha mer än 50% reaktiv effektkompensation. Om denna gränsöverskrids kan strömmen i strömbrytaren inte ha noll genomgang efter aktivering,kallad noll saknad fenomen. Detta är problematiskt om ett fel inträffar strax efteraktivering. Under de senaste 10 åren har olika metoder föreslagits, vilket skullemöjliggöra större reaktiv effektkompensation. Dessa metoder hindrar antingen detnollbristande fenomenet (förebyggande metoder) eller ger ett sätt att öppna strömbrytarenom ett fel uppstår (hanteringsmetoder).En ny 200 km, 220 kV linje har föreslagits på Island kallad Sprengisandslína. Ettföreslaget alternativ för att den här linjen ska byggas är att bygga den som en OHLUGC-OHL-linje, eftersom spänningskriterierna inte är uppfyllda om Sprengisandslínaär byggt som en UGC med en 50% reaktiv effektkompensation. Syftet meddenna avhandling är att se huruvida det saknade fenomenet kan undvikas genomatt genomföra motåtgärder - detta ger ett preliminärt resultat om Sprengisandslínakan byggas som en UGC. I denna avhandling analyseras de fyra olika förebyggandemetoderna med en övergående studie för Sprengisandslína: (1) Förinsättningsresistor,(2) Synkroniserad samtidigkoppling, (3) Synkroniserad inkoppling där kabelnaktiveras före shuntreaktorn och (4) ) synkroniserad inkoppling där shuntreaktornaktiveras före kabeln.Preliminära steady state studier utförs för att bestämma det minsta antalet shuntreaktorersom behövs för att uppfylla spänningskriterierna. Resultaten visade att detminsta antalet som behövdes var tre förutsatt att de alla är lika stora som liggerjämnt längs kabeln (en i varje ände och en i mitten). Dessutom är det nödvändigtatt se om generatorer skulle bli underexiterad om kabeln är energiserad med 100%iiiivreaktiva effektkompensation eftersom det kan minska generatorns livslängd. Resultatenvisade att generatorer inte blev underexiterad.Motståndet för synkroniserad omkoppling där shuntreaktorn aktiveras före kabelnoch motmätningen av samtidig synkroniserad omkoppling visades för att elimineradet nollmissande fenomenet när kabeln aktiverades med 100% reaktiv effektkompensation.Synkroniserad omkoppling där shuntreaktorn aktiveras innan kabeln visadesig ha lägre omkopplingsvolymer, 21% högre än nominellt värde och den lägre inbrusningsströmmenpå 2,38 kA. Metoden för samtidig synkroniserad omkopplingär emellertid billigare och omkopplingsvolymen och inströmmen var inom en acceptabelmarginal (omkopplingsvolymer var 35; 9% högre än nominellt värde ochinströmningsströmmen var 4,01 kA).De resultaten av studien indikerar att Sprengisandslína kan energiseras som en UGCmed 100% reaktiv effektkompensation om antingen motspelet av samtidig synkroniseradomkoppling eller synkroniserad omkoppling där shuntreaktorn aktiveras innankabeln installeras. En detaljerad frekvensstudie måste dock utföras innan någon avmotåtgärderna kan rekommenderas.

The stress ribbon system has numerous advantages, that includes but are not limitedto: increasing overall stiffness, control deflections and reduction of materialsconsumption, which in turn, reduces the load and the cost. Nevertheless, its use isusually limited to bridges, in particular, pedestrian bridges; this can be attributedto the insufficient space that buildings’ usually have for end supports, or/and backstayedcables, that can accommodate the expected high pull-out forces occuring atthe cables’ ends. In this work, the roof of Västerås Travel Center, which will become one of the longestcable suspended roofs in the world, was chosen as a case study. The aim was toinvestigate the optimal technique to model the post-tensioned stress ribbon systemfor the roof structure using SAP2000, and to assess any possible reduction in thepull-out forces, deflections and concrete stresses. Subsequently, a conventional cablesuspended roof was simulated, using SAP2000, and compared to the post-tensionstress ribbon system in order to examine the potential of the latter. Moreover,the effects of temperature loads and support movements on the final design loadswere examined. Based on the study, a few practical recommendations concerningthe construction method and the iterative design process, required to meet thearchitectural geometrical demands, are stated by the authors. The results showed that the post-tensioned stress ribbon system reduces the concretestresses, overall deflections, and more importantly, reduces the pull-out forces by upto 16%, which substantially reduces the design forces for the support structures.The magnitude of these reductions was found to be highly correlated to the appliedprestressing force, making the size of the prestressing force a key factor in the design.
Konstruktioner med spännbandsystem bestående av bärande huvudkablar medpålagda plattor, ofta av betong, har många fördelar. Dessa fördelar inkluderarmen begränsas inte till ökad totalt styvhet, kontrollerade nedböjningar och reduceradmaterialförbrukning, vilket minskar lasten och kostnaden. Deras användningär dock vanligen begränsad till broar, särskilt gång- och cykelbroar, där det finnsutrymme för att förankra de höga utdragskrafterna från huvudkablarna. Motsvarandeutrymme finns sällan i byggnader. I det föreliggande arbetet har taket till Västerås Resecentrum valts ut som studieobjekt.Taket kommer att bli ett av väldens längsta kabelburna takkonstruktion.Syftet är att undersöka den optimala tekniken för att modellera ett efterspänt spännbandsystemför taket med hjälp av FE-programmet SAP2000 och att bedöma eventuellaminskningar på utdragskrafter, nedböjningar och betongspänningar. Däreftermodellerades en konventionell kabelburen takkonstruktion med SAP2000, och detjämfördes med det efterspända spännbandsystemet för att undersöka fördelarna avdet sistnämnda. Dessutom har effekten av temperaturlasten och upplagsrörelserundersökts på den slutliga modellen. Slutligen ges några praktiska rekommendationerom byggteknik och en iterativ dimensioneringsprocess som är nödvändig förarkitekturgestaltning och dess krav på geometri. Resultaten visar att det efterspända spännbandsystemet gav lägre betongspänningar,mindre totaltnedböjning, och ännu viktigare, mindre utdragskrafter. Krafterna minskade16%, vilket gav en minskning av konstruktionens horisontella upplagsreaktion.Storleken på reduktionen var direkt proportionell mot spännkraften, så förspänningär en nyckelfaktor vid dimensioneringen.

[Truncated abstract] As a consequence of the increase in terrorist incidents, many comprehensive researches, both experimental and numerical modelling of structure and blast interaction, have been conducted to examine the behaviour of civilian structures under dynamic explosion and its impact. Nevertheless most of the works in literature are limited to response of simple structures such as masonry walls, reinforced concrete beams, columns and slabs. Although these studies can provide researchers and structural engineers a good fundamental knowledge regarding blast load effect, it is more likely for blast load to act upon entire structures in actual explosion events. The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damage. Therefore it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, bridges are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. This thesis focuses on the study of the response of a modern cable-stayed bridge under blast loadings. ... Firstly, analysis is conducted to examine the failure of four main components namely pier, tower, concrete back span and steel composite main span under close proximity dynamic impact of a 1000 kg TNT equivalent blast load. Secondly, based on such results, the remainder of the bridge structure is then tested by utilizing the loading condition specified in the US Department of Defence (DoD) guideline with the aim to investigate the possibility of bridge collapse after the damage of these components. It is found that failure of the vertical load bearing elements (i.e. pier and tower) will lead to catastrophic collapse of the bridge. Assuming that terrorist threat cannot be avoided, hence protective measures must be implemented into the bridge structure to reduce the damage induced by explosive blast impact and to prevent bridge from collapse. As such, a safe standoff distance is determined for both the pier and tower under the blast impact of 10000 kg TNT equivalent. This information would allow the bridge designer to identify the critical location for placing blast barriers for protection purpose. For the case of bridge deck explosion, carbon fibre reinforced polymer (CFRP) is employed to examine in respect of its effectiveness in strengthening the concrete structure against blast load. In this research, appropriate contact is employed for the numerical model to account for the epoxy resin layer between the CFRP and concrete. In addition, to ensure that the CFRP can perform to its full capacity, anchors are also considered in the numerical study to minimize the chance of debonding due to the weakening of the epoxy. The results reveal that although severe damage can still be seen for locations in close proximity to the explosive charge, the use of CFRP did reduce the dynamic response of the bridge deck as compared to the unprotected case scenario. Further investigation is also carried out to examine the change in damaged zone and global response through variation in CFRP thickness.

Terremotos recientes han demostrado la gran vulnerabilidad de algunos puentes ante movimiento fuerte. Los de tipo atirantado constituyen una tipología estructural muy atractiva, y que actualmente es empleada para muchos fines prácticos, por lo que es necesaria su protección sísmica. Entre las actuales estrategias de protección, el uso de dispositivos pasivos es la más robusta, económica y apropiada opción para mejorar el desempeño sísmico de estructuras, de entre los que destacan los sistemas de disipación de energía adicional como una buena alternativa. Debido a sus capacidades, fácil recambio y mantención, así como su buen comportamiento mecánico, los amortiguadores de fluidos viscosos son un excelente sistema de disipación de energía para proteger grandes estructuras contra eventos sísmicos intensos. Es por ello que el análisis, evaluación y comparación de la respuesta sísmica no lineal de puentes atirantados de hormigón, con y sin la incorporación de amortiguamiento viscoso suplementario, con el propósito de investigar su efectividad ante eventos sísmicos, es el principal objetivo de esta investigación aplicada.

Para alcanzar lo antes expuesto, se definieron previamente ocho modelos teóricos de puentes atirantados basados en los internacionalmente conocidos puentes de Walter [Walter, 1999], considerando variaciones del esquema de atirantamiento, nivel del tablero, tipo de tablero y espaciamiento de los cables. Como punto de partida para el análisis dinámico no lineal, se realizó un análisis estático no lineal para todos los casos. Luego, se llevó a cabo una caracterización dinámica de los puentes mediante un análisis modal. Como primera aproximación a la respuesta sísmica de los modelos, se ejecutó un análisis mediante espectros de respuesta para cada caso, con el propósito de comparar el comportamiento sísmico en función de las principales variaciones consideradas, y para seleccionar los dos modelos más representativos para ser analizados usando análisis no lineal paso-a-paso. En seguida, se analizaron las estructuras elegidas en el paso previo mediante uso de análisis temporal no lineal por integración directa, sin la consideración de amortiguamiento viscoso suplementario, y tomando en cuenta sismos de campo lejano y campo cercano. En este sentido, se aplicaron cinco eventos sísmicos artificiales para el análisis de campo lejano, y cinco eventos reales que incorporasen pulsos de velocidad de período largo para el análisis de campo cercano, según el Capítulo 3. Finalmente, el análisis de la ubicación óptima de los amortiguadores, un estudio paramétrico tendiente a seleccionar los parámetros óptimos de los mismos, y el análisis paso-a-paso no lineal considerando los amortiguadores viscosos definitivos, fueron investigados con la idea de comparar las respuestas en función de la naturaleza del evento sísmico y el tipo de atirantamiento de los cables, considerando los mismos eventos sísmicos antes expuestos.

Los resultados de la investigación muestran que la aplicación de amortiguamiento viscoso suplementario es una eficiente estrategia para incrementar el amortiguamiento de una estructura, absorbiendo una gran cantidad de la energía de entrada, y controlando la respuesta de estructuras de período largo, sobre todo en la dirección longitudinal, en donde se manifiestan las mayores respuestas. Más de un 55% de la energía de entrada puede ser disipada usando éstos dispositivos, los cuales resultan ser igualmente efectivos para sismos de campo lejano y campo cercano, con independencia del esquema de atirantamiento empleado, por lo que constituyen una excelente estrategia de protección pasiva. Debido a la gran no linealidad de éstas estructuras, el método del espectro de respuesta debe ser considerado sólo como primera aproximación al problema, y para propósitos comparativos. Para resultados más precisos, y para aplicaciones de diseño, el análisis no lineal paso-a-paso es siempre la mejor opción. Por otro lado, ésta investigación prueba el despreciable efecto del esquema de atirantamiento en la respuesta sísmica, así como el importante aumento de la respuesta cuando son tomados en cuenta los efectos tipo pulso de la directividad de la falla, característicos de sismos de fuente cercana.
Recent seismic events have demonstrated the vulnerability of some bridges under strong ground motions. Cable-stayed bridges are an attractive bridge typology currently used for many practical purposes, constituting important structural systems to be protected against earthquakes. Amongst the current seismic protection strategies, the use of passive devices is the most robust, economic and well-suited option to improve the seismic performance of structures, in which additional energy dissipation systems is good choice. Because of their capacities, easy replacement and maintenance, as well as their interesting mechanical properties, fluid viscous dampers could be an excellent additional energy dissipation system to protect large structural systems against strong earthquakes. For that reason, the analysis, assessment and comparison of the nonlinear seismic response of concrete cable-stayed bridges, with and without the incorporation of nonlinear fluid viscous dampers in order to investigate their effectiveness for seismic protection purposes, is the main objective of this applied research.

To reach the proposed objectives, firstly, eight theoretical cable-stayed bridge models based on the well-known Walter's Bridges [Walter, 1999] were defined; considering variations of the stay cable layout, deck level, deck type and stay spacing. As a starting point of the nonlinear dynamic analysis, a nonlinear static analysis was performed for all the cases. After that, the dynamic characterization of the models was carried out by means of a modal analysis. As a first approach of the seismic response of the bridges, response spectrum analysis was performed in order to compare the seismic behaviour as function of the main variations considered, and to select the two most representative bridges to be analyzed using nonlinear time history analysis. The following stage was the seismic analysis of the selected bridge models from the previous step, applying nonlinear direct integration time history analysis, without additional energy dissipation devices, and considering both far-fault and near-fault ground motions. In these sense, five artificially generated earthquake events were considered for the far-fault analysis, as long as five real earthquake events containing long-period velocity pulses were included for the near-fault analysis, according to Chapter 3. Finally, the analysis of the optimal layout of the dampers, a parametric study to select the optimal damper parameters and the nonlinear step-by-step analysis considering the incorporation of the definitive fluid viscous dampers were investigated in order to compare the seismic responses as a function of the earthquake nature and stay cable layout, taking into account the same earthquake events before mentioned.

Results of this investigation show that application of fluid viscous dampers as additional passive energy dissipation systems is a very efficient strategy to increase the damping of a structure, absorbing a significant amount of the seismic input energy, and controlling the seismic response of long-period structures, mainly in the longitudinal direction, where the main responses occur. More than 55% of the input energy can be dissipated with these devices, being equally efficient for far-fault and near-fault ground motions, independent on the stay cable layout, which constitutes a very promising strategy to protect cable-stayed bridges against earthquakes. Because of the highly nonlinear behaviour of those structures, response spectrum analysis must be considered only as first approach to the seismic response and for comparative purposes. For more accurate analysis results, and for design applications, nonlinear time-history analysis is a necessary choice. Likewise, it is demonstrated that the effect of the stay cable layout on the nonlinear seismic response of the bridges is not very important, as well as an important increase of the seismic response when forward rupture directivity pulse effects are considered, a characteristic of near-source ground motions.

[ES] En los últimos años, se han desarrollado numerosos tipos de recubrimientos superficiales frente a la corrosión basados especialmente en aleaciones de cinc-aluminio-magnesio (conocidas como aleaciones "ZM"), como alternativas a los recubrimientos tradicionales basados en cinc (conocidos como "Z"), con el fin de mejorar sus características técnicas y reducir su coste. Los fabricantes de estos nuevos tratamientos reivindican una mayor resistencia a la corrosión, basándose en ensayos de corrosión acelerada y ensayos de campo, estos últimos de muy pocos años de duración. La presente tesis, tiene como principal objetivo la estructuración y análisis de toda la información existente en el actual estado de la técnica, y en particular, el estudio de los ensayos de campo existentes para corroborar su resistencia a la corrosión en distintos tipos de ambientes y a partir de ello, proponer un modelo matemático que facilite su cálculo a largo plazo. Se presenta una revisión del estado de la técnica de recubrimientos metálicos basados en aleaciones ZM, que cubre su evolución en el tiempo, las diferentes calidades y designaciones existentes en el mercado, su estructura y composición, normas internacionales que los regulan y una detallada investigación sobre ensayos de campo en localizaciones de todo el mundo, habiéndose encontrado ensayos de una duración máxima de 6 años. A partir del análisis de estos ensayos de campo, se propone una Metodología para verificar el rendimiento y la evolución de la función corrosión-tiempo, en los diferentes ambientes de exposición, categorizados a través de la norma internacional ISO 9223 (ISO, 2012), que los denomina "categorías de corrosividad", y que abarcan desde C1 (muy bajo) hasta CX (extremo). Este análisis ha clasificado todos los resultados de los ensayos por material, categoría de corrosividad y evolución a lo largo del tiempo. De esta forma, cada categoría de corrosividad ha sido investigada en profundidad, mediante un análisis estadístico, poniendo especial énfasis en la corrosión anual, medida como pérdida de masa (µm / año), la función corrosión-tiempo y su ajuste a un determinado comportamiento. Se han analizado asimismo los recubrimientos Z con el fin de poder comparar ambas alternativas y corroborar la hipótesis de partida, cuyo supuesto principal es la mayor resistencia a la corrosión de las aleaciones ZM frente a los recubrimientos Z. Este análisis ha sido el punto de entrada, para establecer un modelo matemático que determine el rendimiento de la corrosión a largo plazo, con el fin de proporcionar a los profesionales de proyectos en la ingeniería, una herramienta que permita estimar la resistencia a la corrosión y la optimización del coste de una instalación cuando se utilizan diferentes tipos de materiales. El compendio de todo este análisis se ha reflejado en el apartado de Resultados y comentarios. La referida metodología, se ha aplicado a un caso de estudio para mostrar cómo seleccionar la calidad del recubrimiento y su espesor óptimo, así como un cálculo de costes, con el objetivo de garantizar los requisitos de un determinado proyecto, en términos de resistencia a la corrosión y coste. Las conclusiones finales ponen de manifiesto que existen algunas ventajas de las aleaciones ZM frente a recubrimientos Z, principalmente en lo que respecta a la resistencia a la corrosión, al haber encontrado relaciones que pueden duplicar y triplicar su rendimiento, en los períodos para los que hay datos disponibles. Del mismo modo, se han encontrado algunas desventajas, que deben investigarse más a fondo en futuros trabajos de investigación, para dar continuidad a esta tesis. Por ejemplo, la limitación de estos recubrimientos para lograr grandes espesores, la limitada duración de los ensayos de campo, el rendimiento en partes específicas de los componentes (cortes, embuticiones, doblados, soldaduras...), etc.
[CA] En els últims anys, s'han desenvolupat nombrosos tipus de recobriments superficials enfront de la corrosió basats especialment en aliatges de zinc-alumini-magnesi (conegudes com a aliatges "ZM"), com a alternatives als recobriments tradicionals basats en zinc (coneguts com a "Z"), amb la finalitat de millorar les seues característiques tècniques i reduir el seu cost. Els fabricants d'aquests nous tractaments reivindiquen una major resistència a la corrosió, basant-se en assajos de corrosió accelerada i assajos de camp, aquests últims de molt pocs anys de duració. La present tesi, té com a principal objectiu l'estructuració i anàlisi de tota la informació existent en l'actual estat de la tècnica, i en particular, l'estudi dels assajos de camp existents per a corroborar la seua resistència a la corrosió en diferents tipus d'ambients i a partir d'això, proposar un model matemàtic que facilite el seu càlcul a llarg termini. Es presenta una revisió de l'estat de la tècnica de recobriments metàl·lics basats en aliatges ZM, que cobreix la seua evolució en el temps, les diferents qualitats i designacions existents en el mercat, la seua estructura i composició, normes internacionals que els regulen i una detallada investigació sobre assajos de camp en localitzacions de tot el món, havent-se trobat assajos d'una duració màxima de 6 anys. A partir de l'anàlisi d'aquests assajos de camp, es proposa una metodologia per a verificar el rendiment i l'evolució de la funció corrosió-temps, en els diferents ambients d'exposició, categoritzats a través de la norma internacional ISO 9223 (ISO, 2012), que els denomina "categories de corrosivitat", i que abasten des de C1 (molt baix) fins a CX (extrem). Aquesta anàlisi ha classificat tots els resultats dels assajos per material, categoria de corrosivitat i evolució al llarg del temps. D'aquesta manera, cada categoria de corrosivitat ha sigut investigada en profunditat, mitjançant una anàlisi estadística, posant especial èmfasi en la corrosió anual, mesura com a pèrdua de massa (µm / any), la funció corrosió-temps i el seu ajust a un determinat comportament. S'han analitzat així mateix els recobriments Z amb la finalitat de poder comparar totes dues alternatives i corroborar la hipòtesi de partida, el supòsit principal de la qual és la major resistència a la corrosió dels aliatges ZM enfront dels recobriments Z. Aquesta anàlisi ha sigut el punt d'entrada, per a establir un model matemàtic que determine el rendiment de la corrosió a llarg termini, amb la finalitat de proporcionar als professionals de projectes en l'enginyeria, una eina que permeta estimar la resistència a la corrosió i l'optimització del cost d'una instal·lació quan s'utilitzen diferents tipus de materials. El compendi de tota aquesta anàlisi s'ha reflectit en l'apartat de Resultats i comentaris. La referida metodologia, s'ha aplicat a un cas d'estudi per a mostrar com seleccionar la qualitat del recobriment i la seua grossària òptima, així com un càlcul de costos, amb l'objectiu de garantir els requisits d'un determinat projecte, en termes de resistència a la corrosió i cost. Les conclusions finals posen de manifest que existeixen alguns avantatges dels aliatges ZM enfront de recobriments Z, principalment pel que fa a la resistència a la corrosió, en haver trobat relacions que poden duplicar i triplicar el seu rendiment, en els períodes per als quals hi ha dades disponibles. De la mateixa manera, s'han trobat alguns desavantatges, que han d'investigar-se més a fons en futurs treballs de recerca, per a donar continuïtat a aquesta tesi. Per exemple, la limitació d'aquests recobriments per a aconseguir grans grossàries, la limitada duració dels assajos de camp, el rendiment en parts específiques dels components (talls, embuticions, doblegats, soldadures...), etc.
[EN] In recent years, numerous types of surface corrosion coatings, based especially on zinc-aluminium-magnesium alloys (known as "ZM" alloys), have been developed as alternatives to traditional zinc-based coatings (known as "Z"), to improve its technical characteristics and reduce its cost. The manufacturers of these new treatments claim greater resistance to corrosion, based on accelerated corrosion tests and field tests, the latter lasting only a few years. The main objective of this thesis is the structuring and analysis of all the existing information in the current state of the art, and in particular, the study of the existing field tests to corroborate their resistance to corrosion in different types of environments and based on this, propose a mathematical model that facilitates its long-term calculation. A review of the state of the art of metal coatings based on ZM alloys is presented, which covers their evolution over time, the different qualities and designations existing in the market, their structure and composition, international standards that regulate them and a detailed research on field tests in different locations around the world, having found tests of a maximum duration of 6 years. From the analysis of these field tests, a methodology is proposed to verify the performance and evolution of the corrosion-time function in the different exposure environments, categorized through the international standard ISO 9223 (ISO, 2012), which calls them "corrosivity classes", and which range is from C1 (very low) to CX (extreme). This analysis has classified all the test results by material, corrosivity class and evolution over time. In this way, each corrosivity class has been investigated in depth, through statistical analysis, with special emphasis on annual corrosion, measured as mass loss (µm / year), the corrosion-time function and its adjustment to a certain behaviour. The Z coatings have also been analysed to be able to compare both alternatives and corroborate the main hypothesis, whose main assumption is the greater resistance to corrosion of ZM alloys compared to Z coatings. This analysis has been the entry point to establish a mathematical model that determines the long-term corrosion performance, to provide project engineering professionals, with a tool to estimate the corrosion resistance and optimize the cost of an installation when different types of materials are used. The summary of all this analysis has been reflected in the Results and discussion section. The referred methodology has been applied to a case study to show how to select the quality of the coating and its optimal thickness, as well as a cost calculation, in order to guarantee the requirements of a specific project, in terms of resistance to corrosion and cost. The final conclusions show that there are some advantages of ZM alloys over Z coatings, mainly with regard to corrosion resistance, having found relationships that can double and triple their performance, in the periods for which there are data available. In the same way, some disadvantages have been found, which must be investigated further in future research works, to give continuity to this thesis. For example, the limitation of these coatings to achieve large thicknesses, the limited duration of field tests, the performance of specific parts of the components (cuts, embossments, bends, welds ...), etc.
Chenoll Mora, E. (2021). Analysis of metallic coatings based in zinc-aluminium-magnesium alloys, in terms of performance and long-term corrosion. Case study: Electrical cable trays selection in project design [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/167418
TESIS

Most engineering systems are highly nonlinear in nature and thus one could not develop efficient mathematical models for these systems. Artificial neural networks, which are used in estimation, filtering, identification and control in technical literature, are considered as universal modeling and functional approximation tools. Unfortunately, developing a well trained monolithic type neural network (with many free parameters/weights) is known to be a daunting task since the process of loading a specific pattern (functional relationship) onto a generic neural network is proven to be a NP-complete problem. It implies that if training is conducted on a deterministic computer, the time required for training process grows exponentially with increasing size of the free parameter space (and the training data in correlation). As an alternative modeling technique for nonlinear dynamic systems
this thesis proposed a general methodology for structured neural network topologies and their corresponding applications are realized. The main idea behind this (rather classic) divide-and-conquer approach is to employ a priori information on the process to divide the problem into its fundamental components. Hence, a number of smaller neural networks could be designed to tackle with these elementary mapping problems. Then, all these networks are combined to yield a tailored structured neural network for the purpose of modeling the dynamic system under study accurately. Finally, implementations of the devised networks are taken into consideration and the efficiency of the proposed methodology is tested on four different types of mechanical systems.

To meet the economic, social and infrastructure needs of the community for safe and efficient transportation systems, long span bridges have been built throughout the world. Long span bridges are one of the most challenging kinds of structures in civil engineering. The cable-stayed bridges are of great interest mainly as an alternative and a more economic solution than the one of suspension bridges. In addition, the fiber reinforced polymer (FRP) composites are, nowadays, successfully used for constructing modern bridges, where the significant weight saving provides additional benefits. Because of the great flexibility, modern long-span cable-stayed bridges are usually very susceptible to dynamic loads especially to the earthquake and strong winds. Therefore, the earthquake-resistant and wind-resistant designs become one of key issues for successful construction of bridges. The objective of the present research is to develop a very efficient spline finite strip technique, for modelling and analysis of both conventional and hybrid FRP cable-stayed bridges. The study falls into the categories of bending, free vibration, seismic, and aerodynamic flutter analysis. The spline finite strip method (SFSM) is one of the most efficient numerical methods for structural analysis of bridges, reducing the time required for estimating the structural response without affecting the degree of accuracy. In the finite strip method, the degrees of freedom could be significantly reduced due to the semi-analytical nature of this method. However, the previous versions of SFSM are not able to model the entire bridge system. For that reason, the structural interactions between different structural components of the bridge could not be handled. In addition, the vibrations and displacements of the towers and cables could not be investigated. In the present formulation, all these obstacles have been eliminated. Moreover, the proposed finite strip technique is very efficient and accurate due to the drastic reduction in the formulation time, simplicity of data preparation, rapid rate convergence of the results, and the semi-analytical nature. Last but not least, and for the first time, a fully finite strip solution is extended to the area of wind engineering. Using the spline finite strip discretization, the aerodynamic stiffness and mass properties of the long-span cable-stayed bridge are derived. The aerodynamic properties along with the structural properties of long-span plates and bridges are formulated in the aerodynamic equation of motion and are used to analyze the flutter problem. The accuracy and efficiency of the proposed advanced finite strip method is verified against the finite element and field measurement results. The results demonstrate that this methodology and the associated computer code can accurately predict the dynamic and aerodynamic responses of the conventional and FRP long-span cable-stayed bridge systems. The outcome of the present research will lead to a comprehensive structural analysis of bridges in the framework of the proposed discretization which is more efficient and straightforward than the finite element analysis.

Dans cette thèse sont analysés les problèmes liés à la CEM qui peuvent se produire dans un réseau électrique industriel de grandes dimensions, prenant en compte les harmoniques introduits dans le système par le découpage des convertisseurs de puissance. Les harmoniques ont été étudiés dans la bande de fréquence entre DC et quelques dizaines de MHz.Pour modéliser la propagation des harmoniques de découpage dans les longs câbles électriques, une méthode de simulation précise et de bas coût computationnel a été proposée. Cette méthode est adaptée pour simuler le comportement des signaux parasite dans les câblages longs présents dans les réseaux industriels, des bâtiments ou autre, et peut être utile pour le dimensionnement de ces réseaux, en vue du développement de méthodes de protection contre des dysfonctionnements et dommages qui peuvent être causés par des phénomènes d'interférence électromagnétique
This work analyses the EMI problems that may arise in the large electric networks on industrial plants, taking into account the switching harmonics injected in these systems by power converters. The harmonics were studied in the frequency band from DC up to a few tens of MHz.To model the propagation of the switching harmonics in long electric cables, an accurate and computationally efficient simulation method is proposed. It is fit to simulate the behavior of medium frequency parasitic signals in large cabling networks, e.g. on industrial plants, buildings, and others. This method can be useful in the designing of such systems, contributing to the development of protection measures against dysfunction or damage that may be caused by EMI phenomena in the network

In questo lavoro sperimentale ed innovativo è stata effettuata una valutazione dell’effetto provocato dall’applicazione di sovratensioni ripetute (“Long TOVs), su provini di polietilene reticolato (XLPE) dello spessore di 0.15mm. Tale Long TOV è stata definita dal CIGRÉ Joint Working Group (JWG) B4/B1/C.4.73, basandosi su sovratensioni registrate nella configurazione bipolare rigida per la trasmissione dell’energia elettrica HVDC. In particolare quando un polo è soggetto a un guasto, il polo sano è soggetto a questa sovratensione che persiste centinaia di millisecondi. I test sono stati svolti modificando le condizioni di invecchiamento come l’intensità del campo elettrico nominale e la durata dell’applicazione delle ripetute forme d’onda Long TOV. La parte immaginaria della costante diellettrica complessa ε”, è stata valutata attraverso una spettroscopia dielettrica sia su provini non invecchiati, sia sui provini invecchiati alle diverse condizioni di invecchiamento. Dopo di chè sono state svolte anche misure sulla spettroscopia infrarossa per valutare la presenza di molecole polari sulla superficie dei provini di XLPE, caratteristiche delle reazioni di ossidazione sintomo di invecchiamento. I test hanno dimostrato che i campioni sono sensibili all’applicazione ripetuta delle Long TOV, in particolare si è notato un picco di valori di ε” attorno alle frequenze di 100 ÷ 103 Hz. Inoltre, questi picchi dipendono dalle condizioni di invecchiamento (durata dell'applicazione e ampiezza del campo elettrico) poiché l'ampiezza dei picchi e la frequenza a cui appaiono variano in funzione di queste due variabili. Per trarre conclusion concrete, un maggior numero di test dev’essere effettuato a differenti condizioni di invecchiamento, in maniera tale da avere una panoramica completa sull’effetto dell’applicazione delle Long TOVs, sui provini di XLPE.

The New Zealand forest industry produces a diverse range of log grades and sorts to meet domestic and export market demands and to maximise returns to the forest grower. An implication for the supply chain is the number of log grades and sorts a harvesting operation is expected to produce from one species, radiata pine (Pinus radiata). The number of log grades and sorts can impact on landing size and layout requirements, value recovery, log-making complexity, machine utilisation and quality control requirements. A study was conducted to investigate if the number of log sorts affects mechanised log processing productivity and value recovery. This would determine if any gross value gains derived from producing a higher number of sorts are offset by losses in log processing productivity. Two landing-based mechanised log processors at cable yarder harvesting operations were studied using different cutting scenarios producing five, nine, twelve and fifteen log sorts. The study collected data from over 26 hours of mechanised processing which included the processing of 578 stems at an average piece size of approximately 1.6 m³. Machine utilisation results showed processors spending 84% of total time on productive tasks and that 49% of total time was spent on the primary productive tasks of log processing. Quadratic regressions were used to model log processing productivity trends which showed piece size and cutting scenario as significant predictor variables (p-value <0.01). There was a significant difference between cutting scenario with five log sorts and the cutting scenarios with twelve and fifteen log sorts (p-values <0.05), as well as a significant difference between the nine and fifteen log sort cutting scenarios (p-value <0.01). There was not enough evidence to suggest productivity was different between cutting scenarios producing five and nine log sorts. Based on this analysis, it was likely that the null hypothesis that the number of log sorts does not affect log processing productivity should be rejected. At a piece size of 2 m³, the productivity model estimated processing productivity was 10% higher producing nine log sorts compared to producing fifteen log sorts. A linear regression model showed a strong relationship between gross value recovery, piece size and cutting scenario (p-value <0.01). Gross value recovery increased as the number of log sorts increased. A significant model suggested it is likely null hypothesis 2, that the number of log sorts does not affect gross value recovery, should be rejected. There were only some differences in variances between cutting scenarios which were statistically significant. Both the average results and regression estimates showed the five log sort cutting scenario recovering 94% of the value of the cutting scenario with fifteen log sorts. Incremental gains in value recovery as the number of log sorts increased were marginal, which appeared to be due to log prices for many major log grades trading in a close range in relation to historic price trends. Regression trends for productivity and gross value recovery indicated that the most optimal cutting scenario, in terms of processing value outturn per productive machine hour, was the cutting scenario producing nine log sorts. This suggests that declines in processor productivity offset gains in gross value recovery when producing twelve and fifteen log sorts. Market sensitivity analysis suggested that differentials in log prices impact on the number of log sorts which optimise the value outturn per productive machine hour from log processing.

In questo studio è stato utilizzato un osservatorio video cablato (OBSEA, www.obsea.es) per il monitoraggio dei ritmi stagionale e annuali della composizione della comunità ittica costiera (20 m) nel Mediterraneo occidentale, in prossimità di una struttura artificiale. Nell’arco di 3 anni (2012-2014) è stata scattata una foto ogni 30 minuti utilizzando una videocamera ad alta risoluzione. Sono state inoltre registrate due importanti variabili ambientali che modulano il comportamento dei pesci: la temperatura dell'acqua e il fotoperiodo. In ogni foto è stato determinato il numero di individui di 6 specie appartenenti alla famiglia degli Sparidi: Dentex dentex, Diplodus sargus, Diplodus vulgaris, Diplodus puntazzo, Diplodus annularis, Diplodus cervinus. La ritmicità delle serie temporali è stata studiata utilizzando il linguaggio di computazione R attraverso uno dei suoi pacchetti aggiuntivi, RAIN. Inoltre, per evidenziare eventuali correlazioni tra le variabili scelte e le specie prese in esame sono state effettuate analisi di correlazione utilizzando il coefficiente per ranghi di Spearman. I risultati indicano che le specie D. dentex, D. sargus, D. annulars, D. vulgaris presentano una ritmicità annuale nella loro abbondanza presso la barriera artificiale. Dall’analisi di correlazione per ranghi di Spearman è stato osservato che la specie D. dentex presenta una correlazione positiva con entrambe le variabili ambientali. Le specie D. sargus e D. vulgaris presentano una correlazione positiva con la temperatura dell’acqua e nessuna correlazione con il fotoperiodo. Il D. annularis presenta una correlazione negativa con entrambe le variabili. Le specie D. puntazzo e D. cervinus non presentano nessuna correlazione con entrambe le variabili. La piattaforma OBSEA ha permesso di eseguire uno studio completo ed ha evidenziato le differenze ecologiche delle specie prese in esame, senza creare perturbazioni associate al campionamento.

Non-Destructive Testing of industrial components carries vital importance, both financially and safety-wise. Among all Non-Destructive techniques, Long Range Ultrasonic Testing utilizing the guided wave phenomena is a young technology proven to be commercially valid. Owing to its well-documented analytical models, Ultrasonic Guided Waves has been successfully applied to cylindrical and plate-like structures. Its applications to complex structures such as multi-wire cables are fairly immature, mainly due to the high complexity of wave propagation. Research performed by the author approaches the long range inspection of overhead transmission line cables using ultrasonic guided waves. Existing studies focusing on guided wave application on power cables are extremely limited in inspection range, which dramatically degrades its chances of commercialization. This thesis consists of three main chapters, all of which approaches different problems associated with the inspection of power cables. In the first chapter, a thorough analysis of wave propagation in ACSR (most widely used power cable) cables is conducted. It is shown that high frequency guided waves, by concentrating the energy on the surface layers, can travel much further in the form of fundamental longitudinal wave mode, than previous studies have shown. Defect detection studies proved the system’s capability of detecting defects which introduce either increase or decrease in cross sectional area of the cable. Results of the chapter indicate the detectability of defects as small as 4.5% of the cross sectional area through a 26.5 meter long cable without any post-processing. In the second chapter, several algorithms are proposed to increase the inspection range and signal quality. Well-documented wavelet-denoising algorithm is optimized for power cables and up to 24% signal-to-noise ratio improvement is achieved. By introducing an attenuation correction framework, a theoretical inspection range of 75 meters is presented. A new framework combining dispersion compensation and attenuation correction is proposed and verified, which shows an inspection range of 130 meters and SNR improvement up to 8 dBs. Last chapter addresses the accurate localization of structural defects. Having proven the optimum excitation and related wave propagation in ACSR cables, a system having a more complex wave propagation characteristics is studied. A new algorithm combining pulse compression using Maximal Length Sequences and dispersion compensation is applied to multi-modal signals obtained from a solid aluminum rod. The algorithm proved to be able to improve signal quality and extract an accurate location for defects. Maximal Length Sequences are compared to chirp signals in terms of SNR improvement and localization, which produced favourable results for MLS in terms of localization and for chirp in terms of SNR improvement.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
The central theme of investigation for this paper is the Brazilian low-budget film industry. As a sample for analysis, we selected a group of seven feature films (A ?ltima estrada da praia, Castanha, Dromed?rio no Asfalto, Sobre sete ondas verdes Espumantes, Morro do C?u, Menos que Nada and O Liberdade), produced in Rio Grande do Sul and commercially released between 2011 and 2015. The study considers the low-budget film industry to encompass feature films with a maximum cost of BRL 1 million. This sample was stipulated based on the budget ranges covered by public policies for film-industry development, specifically the public notice for Low-Budget Feature Films from the Ministry of Culture's Audiovisual Secretariat. The paper sought to unveil the specific production and circulation methods for low-budget films, especially those covered by the scope of analysis. In this process, we began with a theoretical contextualization based on the investments from studies on the cultural economy, the film-making economy and the Brazilian film industry, while also mapping public policies for the development of the industry and market data that allowed us to outline the panorama in which the low-budget film industry of Rio Grande do Sul is inserted. For the study of selected films, we employed on-site, semi-structured interviews with the producers, which provided us with access to production records for the films and significant information in understanding the practice of low-budget film-making within a regional context. In this analysis we noted that, among other characteristics, the low-budget film industry of Rio Grande do Sul is punctuated by the use of smaller and similar teams in accord with the production unit, the professional character of the producers, the majority of whom originate or are still academically linked to higher education audiovisual programs; by the flexibility in work relationships and by capturing resources in stages, with the greatest difficulties faced in the finalization phase.
Esta tese tem como linha de investiga??o central o cinema de baixo or?amento brasileiro. Como recorte para a an?lise, selecionamos sete longas-metragens (A ?ltima estrada da praia, Castanha, Dromed?rio no Asfalto, Sobre sete ondas verdes espumantes, Morro do C?u, Menos que Nada e O Liberdade) realizados no Rio Grande do Sul e lan?ados comercialmente entre 2011 e 2015. A pesquisa entende como cinema de baixo or?amento os filmes de longa-metragem com custo m?ximo de R$ 1 milh?o. Esse recorte foi estipulado a partir de faixas or?ament?rias abrangidas por pol?ticas p?blicas de fomento ao cinema, em especial o edital para Longas de Baixo Or?amento da Secretaria do Audiovisual do Minist?rio da Cultura (Minc). O trabalho procura entender quais os modos de produ??o e circula??o espec?ficos dos filmes de baixo or?amento, em especial aqueles apreendidos pelo corpus da an?lise. Nesse processo, partimos de uma contextualiza??o te?rica baseada nos aportes dos estudos de economia da cultura, da economia do cinema e do cinema brasileiro, assim como de mapeamentos de pol?ticas p?blicas de fomento ao setor e dados mercadol?gicos que nos permitiram elaborar o panorama no qual est? inserido o cinema de baixo or?amento do Rio Grande do Sul. Para o estudo dos filmes selecionados, utilizamos entrevistas presenciais semi-estruturadas com os realizadores, as quais nos permitiram acessar as mem?rias de produ??o dos filmes e informa??es significativas para a compreens?o da pr?tica do cinema de baixo or?amento em um contexto regional. Identificamos, nessa an?lise, que o cinema ?B.O.? sul-rio-grandense ? marcado, entre outras caracter?sticas, pela utiliza??o de equipes enxutas e similares de acordo com o n?cleo de produ??o, pelo car?ter profissional dos realizadores, a maioria oriunda ou ainda vinculada academicamente aos cursos superiores da ?rea audiovisual; pela flexibiliza??o das rela??es de trabalho e pela capta??o de recursos em etapas, com maior dificuldade concentrada na fase da finaliza??o.

碩士
國立高雄大學
土木與環境工程學系碩士班
107
The cable-stayed bridge structure system is fixed to the pylon through one end of the cable, and the other connects with the deck to pull up the deck. If the cable is damaged, the structurl safety of the cable-stayed bridge may be affected. It may led to the bridge collapse in serious. Therefore, this study analyzed the long-term monitoring data of Kao Ping Hsi Cable-Stayed Bridge and then estimated the cable frequency and forces. The structure system of a cable-stayed bridge is to fix the pylon through one end of the cable and is to connect the other end with the deck, as to pull up the bridge structure. If one of the cables got broken, it would affect the structural safety of the bridge structure, and in the worst case the bridge would collapse. This study first collected the monitoring data of Kao Ping Hsi Cable-Stayed Bridge dated from December 2017 to November 2018. The data were then analyzed using Fourier transform and the obtained frequencies were used to estimate the cable forces. The result of the analysis was finally used to set up a warning system, which helps check if the cables need repairing or replacing.

碩士
中原大學
土木工程研究所
93
A finite element computation procedure for static and dynamic analysis of 2-D and 3-D long-span cable-stayed bridge under action of seismic loads is presented in the study. The Three Span Twin Tower Symmetric Cable-Stayed Bridge is taken as example. The system equation of cable-stayed bridges including the nonlinearities due to beam-column, cable sag and large displacement effects are considered. First of all, the initial shape of cabled-stayed bridge is determined by using shape iteration technique. Based on the initial shape the deflection, natural frequencies and modes and dynamic responses seismic action are determined. The numerical results show that the vibration of girder appears in the form of anti-symmetry under horizontal X seismic excitation. The mid point of girder has no displacement. After considering the large displacement effect, the non-linear effect is comparatively obvious. The vibration of girder appears in the form of symmetry under vertical seismic excitation.

碩士
中華大學
土木工程學系碩士班
93
Cable-stayed bridges have large deformation because of smaller stiffness, therefore, geometrical and material nonlinear analysis of flexible cables are token into account in this study. Cable-stayed bridges are traditionally constructed with steel cables. However, steel cable always has corrosion problems. As carbon fiber composite cable possesses the anti-corrosion merit, it becomes an important issue to investigate the possibility of using carbon fiber composite cable instead of steel cable. In this paper, the analytical models of long-span cable-stayed bridges with carbon fiber composite cable and steel cable are established, and the analytical results are examined. There are two models established in this paper, one is for analyzing the structural behaviors of the long-span cable-stayed bridges under dead load and live load, the other is for those under wind load. In addition, the influence of cable to the structural behaviors of the long-span cable-stayed bridges is examined as well. The numerical results have shown that, the axial stiffness of carbon fiber composite cable is less than that of steel cable, due to the elastic modulus of carbon fiber composite cable less than that of steel cable. The results have also shown that after using carbon fiber composite cable, the moment and the vertical displacement of main girder, as well as the moment and the horrizontal displacement of tower have increased. However, the tensile force of cable and the axial force of main girder and tower have decreased. In addition, the static instability under wind load becomes significant while using carbon fiber composite cable, and the ultimate load-bearing capacity had increased. This research demonstrated that using carbon fiber composite cable instead of steel cable is an acceptable choice.

碩士
中原大學
電機工程研究所
95
This thesis in to steady the ground fault current and voltage appeared on grounding system and cable shielding conductor with may produce hazard on personnel and cables for the large plant with long cable interconnections to cable connection station (CCS) ﹒The single-phase-ground faults with respect to the fault locations of main transformer, switchyard and CCS are analyzed by using electromagnetic transient program/alternative transient program(EMTP/ATP) and considering transient state and steady state of ground fault﹒The circuit model constructed by EMTP/ATP will take the ground grids of generation unit, switchyard and CCS into account﹒The cross bonding and surge arresters installed in the cable cover protection unit (CCPU) for cable shielding conductors are considered in the model﹒All the analysis will aim to the main transformer neutral points with solid grounded and with arresters Based on the analysis results of fault currents injected into ground grids , a soft were package called CDEGS is used to analyze the characteristics of grounding system including ground potential rise(GPR) , touch voltage , step voltage and electromagnetic field distributed on the ground surface﹒The affections of these characteristics on personnel and equipments are evaluated﹒The study results had shown that danger touch voltage will appear on fault points and cable shielding conductor﹒Several kV and kA of cable shielding conductor voltages and currents will be arrised ﹒Thus , cable shielding conductors with defect connection may induce large hazard due to their high voltages and currents﹒

碩士
長庚大學
電機工程研究所
93
This paper introduces the transients over voltage analysis of a long distance cable fed transformer system with the EMTP-RV and ATPDraw. First, the transient over voltage behaviors and the insulation coordination of power system are induced. Then, an industrial power system with a long distance cable fed transformer is built for transient over voltage analysis. The EMTP-RV and ATPDraw is employed for simulation. Several possibly occurred cases regarding transient over voltage phenomena are chosen for simulations and evaluations. Finally, the capacitance of the cable is neglected for additional simulations and comparisons.

碩士
中原大學
土木工程研究所
93
Early of the Twentith century, suspended bridge is the main type of the bridges such as Golden Gate bridge in 1937. With the computer development, cable-stayed bridges are on the upgrade after the world war Ⅱ. People have some demands about environment, economics, esthetics, and comfort, besides security. Because the cable-stayed bridge fit in with the conditions, it becomes one of the main types of the bridges. For cable-stayed bridges, the first course is the influence of the flutter, the buffeting, and the vortex shedding in cable-stayed bridge’s design and analysis. This article is composed with wind tunnel test of a cable-stayed bridge designed for the Taipei metropolitan area(include section model test and full model test) and the result of the formulas for wind velocity of flutter, buffeting, and vortex shedding. With the development and the progress of the bridge engineering technique, the span of the bridge is getting longer. The influence of the wind-force is an important factor that can't be ignored in long-span bridges design.

碩士
中原大學
電機工程研究所
93
This work regards the characteristics of grounding system during steady state grounding fault on the multi-unit large plant with long cable connection to system. The ground potential rises (GPR), touch voltages, step voltages and electromagnetic fields caused by grounding fault are first analyzed by the software “CDEGS”, and the current and voltage distributions on the shielding conductors of cable are studied. In the thesis, the worst fault current is analyzed by sequence network where the ground grids of generator unit and switch yard and cable shielding conductors are considered. The study results had shown that the ground fault current will increase with the number of main transformer with neutral grounded directly. This will increase the hazards in the switch yard ground grid. The effects of capacitances of the cable on steady state ground fault current can be neglected. This study provides useful data for planning the improvement strategies of large plant ground system.

碩士
中原大學
電機工程研究所
93
The switching surge characteristics in a large plant with long cable connection are more serious than other conventional plant due to large capacitances in the cables. Both power system and grounding system suffered from switching surge, the latter produces various electromagnetic phenomena including ground potential rise(GPR), step and touch voltages, and magnetic field distributions. This thesis analyzes these phenomena and assesses their affections on personnel and equipments in the plant. The electromagnetic transient program(EMTP) is used for analyzing the switching surge currents and voltages on the various important grounding points, and then a software namely “Current distribution electromagnetic grounding and soil structure”(CDEGS) is used for analyzing the electromagnetic phenomena distributions. Both the EMTP model and CDEGS model are constructed where the grounding scheme and various parameters are detail defined ,Further more, the switch operation modes, different neutral grounding conditions of main transformer, unit connect types and the residual voltage in cable inner conductor are taken into considerations for the analysis of switching surge currents and voltage ,and various electromagnetic distributions on the ground grids. The results of analysis and assessments have shown that bad switching surge characteristics of grounding system due to long cable are found. This will lead to adverse effects on the safeties of personnel and equipments in the plant . The study had also provided some useful data of some phenomena for improving the switching surge characteristics of grounding system in the plant.

碩士
中原大學
土木工程研究所
93
Abstract Long-span cable-stayed bridge is a very important trend of technological development of modern bridge. Cable-stayed bridge composed of three major components which are deck, pylon and cable. The anchorage design of the pylon is the key part of the design of cable-stayed bridge. The design principle focuses on the determinate design force with simple structural model to make the replacement of cables and construction feasible. The stress concentration phenomena of the anchorage zone could be very complicated and significant, therefore, prestressed steel bars are used to resist the cable force. In this paper, the numerical analysis of the anchorage zone of the cable-stayed bridge designed for Taipei metropolitan area is carried out by ANSYS 8.1, the analysis software of FEM. The goal is make sure the safety of the anchorage zone of the cable-stayed bridge. Key words: cable-stayed bridge; concrete pylon; stress analysis

碩士
淡江大學
國際貿易學系國際企業學碩士班
93
Nowadays, cable television hardware suppliers in Taiwan are facing factors of limited growth of subscription, technology progress, digitalized challenges, impacts from cross-competitions and tendency to cooperate for multimedia industry. Consequently, cooperation relationship is gradually built up with parties in industry in order to raise competitive advantages. It lacks of long-term cooperation relationship studies in academic research for cable television industry. Therefore, this thesis is based on the vertical cooperation between domestic cable television hardware suppliers and cable television system operators to analyze the factors that influence long-term cooperation relationship between organizations, relationship quality effects toward to the long-term relationship, role position of switching barrier in cooperation relationship and factors that composed relationship quality. This thesis is a case study of cable television hardware suppliers in Taiwan. We analyzed 62 effective surveys, in order to understand how variable evaluation for relationship quality and switching barrier influences long-term cooperation relationship. Conclusions are as followings: 1.Customer satisfaction and switching cost are major factors that influence long-term cooperation relationship development between organizations. 2.Customer satisfaction is the major factor of relationship quality that influences persistency of the long-term cooperation relationship. 3.Due to the characteristics of CATV industry, switching barrier and long-term cooperation relationship respond to the significant positive phase level as result in switching barrier. 4.Essentials that compose relationship quality are trust, relationship commitment and customer satisfaction. However, customer satisfaction is the most important and influences mostly to the relationship quality.

碩士
國立高雄應用科技大學
電機工程系博碩士班
104
In recent years, in order to enhance the electricity quality and to reduce the people’s contend, transmission line is designed with underground approach for urban area and science parks. Since the voltage level of cable become larger and severed transient behavior seriously affect system reliability, the underground cable is necessary from EHV substation to EHV substation. Once cable is striking by switching impulse and its transient is travelling along cable; the damage will seriously affect the operation and life time of cable. In order to increase the cable operating life time, the explore and analysis of switching transient is required. This thesis applies the EMTP/ATP software tool to establish the equivalent circuit model to simulate the behavior of circuit breaker switching transient for underground cable. A 10 km Kaokang-Wuchia section of Kaokang-Wuchia-Kaohsiung loop built in 2014 is selected for computer simulation examined the correlation between switching transient and cable characteristics to justify the effectiveness of the proposed method.The simulations results can be used as reference for design of underground cable of Taipower. Moreover, the proposed method will apply to other transmission line to enhance the electricity quality and reliability.

碩士
國立交通大學
電子工程系所
94
Cable discharge event (CDE) has been the main cause which damages the Ethernet interface. The transmission line pulsing (TLP) system has been the most important method to observe the electric characteristics of the device under human-body-model (HBM) ESD stress. To understand the physical characteristics and CDE robustness of protection device in the wafer level, the long-pulse transmission line pulsing (LP-TLP) system has been set up and used to simulate the influence of CDE on the Ethernet integrated circuits and to measure and analyze the secondary breakdown characteristics of the CDE protection devices. Furthermore, the measured results by using the LP-TLP system are compared with those by using the traditional 100-ns TLP system. The experimental results have shown that the CDE robustness of NMOS and PMOS devices in deep-submicron CMOS technology is much worse than their HBM ESD robustness.

碩士
中原大學
電機工程研究所
94
Abstract In the large plant with long cables interconnection between generator units and switchyard , large current and high voltage will appear on the cable shielding conductors and grounding system during ground fault on switchyard. Form which the cable and equipment may be damaged even hurt personnel. In this thesis , typical plant with the above problems is studied , The circuit model based on electromagnetic transient program/alternative transient program (EMTPATP) is constructed and analyzed for ground fault on the switchyard at transient state and steady state . The ground grids of switchyard and generator units , the phase conductor and shielding conductors of cable and the main transformer of generation unit are all considered in the modal . In which , the cable shielding conductor with cross-transposition-connection and grounded by arrester in the cable-cover-protection unit (CCPU) are detailly considered in the model . The grounded types of neutral points of mantransformers of generator unit and starting transformer include solid-grounded and arrester-grounded type which are considered is the analysis of ground fault . The transient state and steady state currents and voltages distributed on the cable shielding conductors and the grounding points of cable shielding conductors and transformer neutral point on the ground grids can be obtained from the simulation by ATP . Finally , the affections of ground fault on the cable and grounding system are evaluated lased on the simulation results. In which , the damages on the connections and CCPU arresters of cable shielding conductor are surveied and the electromagnetic characteristics of ground grids are further analyzed by a software package, namely, “current distribution electromagnetic grounding and soil structure analysis”(CDEGS). From which ,we can obtain the electromagnetic the distribution of ground potential rises (GPR) , touch voltage ,step voltage and electromagnetic field on the ground surface of ground grids of switchyard and generate unit . Based on the electromagnetic characteristics , their affections on personnel and equipment are assessed . In the whole ,the study results have shown that the personnel and equipments will be danger at switchyard and touch to cable may shielding conductor during ground fault , and the cable may be damaged by large current with several kA and high voltage kV on the shielding conductors if their connection parts are not treated well.

This study contributes to the search for metrical order in the 90,000 extant long lines of the late fourteenth-century Middle English Alliterative Revival. Using the 'Gawain'-poet's 'Patience' and 'Cleanness', it refutes nineteenth- and twentieth-century scholars who mistook rhythmic liveliness for metrical disorganization and additionally corrects troubling missteps that scholars have taken over the last five years. 'Chapter One: Tame the "Gabble of Weaker Syllables"' rehearses the traditional, but mistaken view that long lines are barely patterned at all. It explains the widely-accepted methods for determining which syllables are metrically stressed and which are not: Give metrical stress to the syllables that in everyday Middle English were probably accented. 'Chapter Two: An Environment for Demotion in the B-Verse' introduces the relatively stringent metrical template of the b-verse as a foil for the different kind of meter at work in the a-verse. 'Chapter Three: Rhythmic Consistency in the Middle English Alliterative Long Line' examines the structure of the a-verse and considers the viability of verses with more than the normal two beats. An empirical investigation considers whether rhythmic consistency in the long line depends on three-beat a-verses. 'Chapter Four: Dynamic "Unmetre" and the Proscription against Three Sequential Iambs' posits an explanation for the unusual distributions of metrically unstressed syllables in the long line and finds that the 'Gawain'-poet's rhythms avoid the even alternation of beats and offbeats with uncanny precision. 'Chapter Five: Metrical Promotion, Linguistic Promotion, and False Extra-Long Dips' takes the rest of the dissertation as a foundation for explaining rhythmically puzzling a-verses. A-verses that seem to have excessively long sequences of offbeats and other a-verses that infringe on b-verse meter prove amenable to adjustment through metrical promotion. 'Conclusion: Metrical Regions in the Long Line' synthesizes the findings of the previous chapters in a survey of metrical tension in the long line. It additionally articulates the key theme of the dissertation: Contrary to traditional assumptions, Middle English alliterative long lines have variable, instead of consistent, numbers of beats and highly regulated, instead of liberally variable, arrangements of metrically unstressed syllables.
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In this work, the inverter is considered the source for HF parasitic effects and therefore thoroughly investigated and modeled. Also, more complex simulation models for cable and motor are developed and analyzed, together with their parameterization methods. A good compromise between model complexity and parameterization simplicity is followed. Next, all individual parts are connected together in an overall simulation model, to reflect the HF phenomena from inverter to motor. The investigated simulation models are verified with measurements at a real setup, a process that allows the iterative improvement of the simulation models. Finally, methods for reduction of overvoltage and common-mode ground current, regarding the improvement of inverter control and the use of inverter-output / motor-input filters are investigated using the complete simulation model and the measurements at the real setup. In the last part of the presented work, an unconventional converter topology is investigated for application with long cables, namely the Quasi-Resonant (QR) DC-link converter. Two major objectives are followed: the main issue here is the motor-friendly characteristic, leading to significant improvement of the motor operation; the secondary objective is to achieve a good efficiency compared to hard-switched converters with inverter-output filters. Finally, both objectives are validated with measurement results.

碩士
國立臺北科技大學
電機工程系所
102
This thesis is to study the protection zone planning of distance relays for long submarine cables of large offshore wind farm. A case study based on Tai-Peng submarine cables of Peng-Hu offshore wind farm with type-C double-fed induction wind generators is presented. A software package namely PSS/E is used for the modeling and simulation. Three protection zones are defined for submarine cable distance relays and the three phase short circuit (3ΦSC) fault characteristics of different protection zones are simulated under different wind farm operation situations. The availabilities of distance relays are surveyed including to find the defects of conventional planning and to proposed improved planning of protection zones. The study results show that the conventional quadrilateral distance relay can not provide sufficient protection for long submarine cables because of neglecting the effects of cable capacitances and the variations of wind farm operation. Therefore, a novel quadrilateral protection zone for distance relay is panned considering the effects of cable capacitances and the variations of wind farm operation. The availabilities of proposed planning had been certified by PSS/E simulation, which is also a good reference for the planning of long cable protection coordination.