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Dissertations / Theses on the topic 'Fiber-optic cable'
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Dorfman, David S., and Frank A. III Strom. "An optimization model for fiber-optic cable installation aboard naval vessels." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34657.
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Approved for public release; distribution is unlimitedThe purpose of this thesis is to develop a cost-optimization model that will help reduce the installation cost of fiber-optic cable onboard new construction naval vessels. The data used to develop the optimization models were collected from visits to naval shipyards and interviews with both fiber-optic cable engineers and installation experts at shipyards, as well as MIL-PRF 85045F and cable manufacturers specification sheets. The information compiled from these sources was used to develop a cable measure of effectiveness that could be inputted into simulation software. Simulations were run to examine the effect of cable quality, quantity, and labor rate in order to select the best fiber-optic cable for installation based on cost risk. Depending on the specifics of a fiber-optic cable run, cable choice can vary, but in general the cable with the highest quality results in a lower risk of cost overruns and is the most cost effective choice over the long run. Program managers and shipyards can easily implement the models developed in this thesis into their current practices for fiber-optic cable procurement and installation aboard U.S. naval vessels.
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Peill, Nicola Joy Hoffmann Michael R. Hoffmann Michael R. "Fiber-optic bundled array cable reactors for heterogeneous photocatalysis and waste stream remediation /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01142008-082303.
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TURNER, WILLIAM C. "ON IMPLEMENTATION OF REMOTELY OPERATED UNMANNED TELEMETRY TRACKING SYSTEMS WITH FIBER OPTIC CABLE." International Foundation for Telemetering, 1991. http://hdl.handle.net/10150/612123.
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International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe high cost of real estate in countries with expanding populations, coupled with the long range capability of modern weapon systems has resulted in the need to expand test ranges to remote desert areas or areas over sea water. In order to preclude the cost of duplicating existing test centers, and the high cost of manually operating ground tracking stations, the requirement for unmanned remotely controlled telemetry tracking systems has emerged. Until recently, implementation of such systems has been trivial because the microwave link had sufficient bandwidth. However, with the advent of multi-TM bands, encrypted T.V. video and dual-polarization diversity requirements, implementation of unmanned remote stations has become cumbersome, expensive and less reliable. For instance, a pair of dedicated computers are now required to remotely control as many as eight receivers and four diversity combiners. This paper analyzes the advantages, limitations and feasibility of remotely controlling a wide-band antenna/pedestal with the restriction that all frequency downconverters, receivers, and combiners be located at the test center where they can be manually controlled and monitored, and more readily maintained. A comparison is made between the use of coaxial cable and fiber-optic cable as short-haul (0.25 to 25 kilometers) RF transmission media.
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Grannis, Betsy M. "Impacts of Mobile Fishing Gear and a Buried Fiber-Optic Cable on Soft-Sediment Benthic Community Structure." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/GrannisBM2005.pdf.
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Nenadovic, Mateja. "The Effects of Bottom-Tending Mobile Fishing Gear and Fiber-Optic Cable Burial on Soft-Sediment Benthic Community Structure." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/NenadovicM2009a.pdf.
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Rumplík, Martin. "Návrh optické sítě pro spojení bytových domů v Kojetíně." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2011. http://www.nusl.cz/ntk/nusl-223154.
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The subject of this diploma's thesis is to create a design of a fiber optic network, which will allow an access to broadband internet connection for households living in blocks of flats in Kojetín. For this purpose the best technologies will be compared by analysis and the new network topology will be designed. The investor is a civic association Cyrilek.net that provides a wireless internet at this area. The best solution will be selected on the basis of financial and technical analysis and the investment will be calculated including its return. This innovation not only give people a really fast internet connection, but also the possibility of other services such as IPTV or VoIP.
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Plodková, Zuzana. "Posouzení spolehlivosti procesu balení optických kabelů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443156.
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The diploma thesis deals with the assessment of the reliability of processes at the packaging center in the company CommScope Czech Republic s.r.o. The first part of the work is research about options for quality management using ISO 9000 standards, but also TQM approaches. At the same time, methods and analytical techniques are discussed, which will be further used in the practical part of this thesis. The following section introduces CommScope Inc. and its main product - optical fiber. The practical part contains an introduction to the packaging center and its processes, it also describes the analysis of the reliability of the original state and proposals for corrective measures that were designed within the Kaizen event. The rest of the work is then devoted to the implementation of the proposed changes and their economic assessment. Finally, an evaluation of the methods used, the results achieved and other recommendations are given.
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Nedoma, Jakub. "Vliv samonosného optického kabelu na mechaniku venkovního vedení VN." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442472.
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This thesis is focused on assessing the impact of retrofitting dielectric All Dielectric Self-Supporting Cable (ADSS) to existing MV overhead line. This type of optical cable is a means of future strengthening of the communication infrastructure of the distribution network. However, its mechanical properties are significantly different from the properties ACSR cable, due to which its installation can be problematic in terms of meeting the requirements of the PNE 33 3301 standard. In practical part, this work deals with the design of the ADSS installation on the existing MV line and the determination of its impact based on the assessment of the results of this design.
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Chittenden, Albert-Bruce. "Extending OWns to include protection functionality." Diss., University of Pretoria, 2005. http://hdl.handle.net/2263/23796.
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The objective of this dissertation is to enhance the functionality of an existing simulation package that is used to simulate fiber optic networks. These enhancements include the capability to simulate protection mechanisms following link failure, which is a necessity in real-world optical networks to ensure the continued flow of information following a failure in a part of the network. The capability for network traffic to choose from additional paths is also an addition to the software. The enhanced, as well as the original simulation software, are open source: this allows anyone to freely modify and improve the source code to suit his or her requirements. This dissertation will focus on mesh-based optical network topologies, which are commonly found in regional optical backbone networks, but which are also increasingly found in metropolitan areas. The regional networks all make use of wavelength division multiplexing (WDM), which consists of putting multiple different wavelengths of light on the same physical fiber. A single fiber breakage will therefore disrupt multiple fiber-optic connections. A fiber-optic network designer has to satisfy various conflicting requirements when designing a network: it must satisfy current and predicted future traffic requirements, it must be immune to equipment failure, but it must also be as inexpensive as possible. The network designer therefore has to evaluate different topologies and scenarios, and a good network simulator will provide invaluable assistance in finding an optimal solution. Protection and restoration need to be looked at in conjunction with routing and wavelength assignment (RWA), to ensure that resources in a network are used at maximum efficiency. Connection restoration time will also be looked at: this should be minimised to ensure minimal network downtime and ensuing loss of revenue. The chosen alternate connection path should also be as short as possible to minimise use of resources and maximise the carrying capacity of the network. Blocking probability (the inability to establish a connection due to a congested network) is a crucial factor and is also investigated. The topologies investigated in this dissertation consist of various mesh based real-world regional WDM fiber-optic networks. The impact of various link failures, the addition of additional alternate paths, as well as the effect of a protection mechanism on these topologies are also investigated. The proposed goals were all successfully achieved. The capability of simulating single as well as multiple link failures was introduced to the simulation package. The blocking probability of various network topologies was compared to each other in the presence of link failures. Success was also achieved in the introduction of a third alternate path to the simulation package.Dissertation (MEng(Electronic))--University of Pretoria, 2005.
Electrical, Electronic and Computer Engineering
unrestricted
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Ee, Chai Chuan. "The feasibility study of implementing a fiber optic local area network in software metrics laboratory in Ingersoll 158." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FEe.pdf.
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Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2004.Thesis advisor(s): Norman F. Schneidewind. Includes bibliographical references (p. 51). Also available online.
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Adelman, Daniel. "Remnant inventory systems." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/25620.
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Perera, Janaka P. "A low-cost man-portable free-space optics communication device for Ethernet applications." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FPerera.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2004.Thesis advisor(s): Gamani Karunasiri, Xiaoping Yun. Includes bibliographical references (p. 47-50). Also available online.
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Kennedy, Christopher. "Properties of High Energy Laser Light Transmission through Large Core Optical Cables." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5797.
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Laser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica glass. Waveguide theory predicts that light traveling through a bend will form whispering-gallery modes that propagate through total internal reflection bounces along the inside of the outer edge of the bend. This is critical since in these locations the energy density of the light will increase significantly, raising the potential of laser damage, nonlinear effects, and transmission losses. This loss is especially problematic when two 90[degree] bends going in opposite directions are in close proximity to each other, forming an 'S-bend'. Light that is grouped along the outer edge going through the first bend will enter the second bend at a sharper angle which causes much high transmission losses and raises the possibility of failure. Models using R-Soft BeamProp and Zemax were developed to study transmission losses, investigate light interactions at critical areas, and predict under which conditions laser damage would occur. BeamProp presents a clearer view of the modal distribution of light within the core of the fiber and is used to analyze how a plane wave with a Gaussian intensity distribution excites the fiber modes. Zemax provides a tool to perform non-sequential ray tracing through the fiber cable and stray light analysis within the core and once the light exits the fiber. Intensity distributions of the cross sectional area of the fiber shows the whispering gallery modes forming as the light propagates around bends and disburses as it propagates afterwards. It was discovered using R-Soft that if the separation distance between bends in an S-bend is approximately 3 mm there exists a condition where maximum transmission occurs. For 365 μm diameter core fiber it was calculated that the difference in output power could be as high as 150%. This was initially completely unexpected; however ray tracing using Zemax was able to verify that this distance allows the light to transition so that it enters the 2nd bend at the optimal angle to enter the whispering gallery mode. Experiments were performed that validated the models' predictions and images were captured clearly showing the spatial distribution shift of the light within the core of the fiber. Experiments were performed to verify light grouping together to form whispering gallery modes as predicted by Zemax. Microscope images were taken as a function of distance from various bends to observe the periodic nature in which the laser light fills up the fiber. Additionally, a configuration was setup to examine stimulated Brillioun scattering and determine the onset of laser damage in the fiber. Fibers were tested as a function of bend radius and number of shots and recommendations for future systems were made. Lastly, mechanical failure tests were performed to determine the relationship between stress placed on the fiber through bending and fiber lifetime in a static environment. This allowed a minimum safe bend radius to be calculated for a 30 year lifetime that agreed with previous calculated values.M.S.
Masters
Optics and Photonics
Optics and Photonics
Optics
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Lafarguette, Romain. "Comment la Technologie Façonne les Marchés Financiers : l’Exemple du Marché des Changes." Thesis, Paris, EHESS, 2017. http://www.theses.fr/2017EHES0042.
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Cette thèse de doctorat est composée de trois chapitres traitant de l’impact des innovations technologiques sur les marchés financiers, prenant comme cas d’étude le marché des changes. Le premier chapitre analyse l’impact des innovations technologiques sur la géographie du marché des changes. Il utilise la connexion des pays au réseau sous-marin des câbles à fibre optique comme mesure de choc technologique exogène. Les estimations montrent que l’introduction des câbles à fibre optique a contribué à concentrer la répartition des activités de trading dans quelques grandes places financières au détriment de toutes les autres. Le deuxième chapitre s’intéresse à l’impact de la technologie sur la réaction des marchés des changes à de nouvelles informations macroéconomiques et financières. Il estime que le développement des technologies de l’information et de la communication permet de réduire la volatilité sur les marchés des changes de façon significative. Enfin, le troisième chapitre montre que le trading à grande vitesse contribue à atténuer les réactions de marché aux chocs macroéconomiques exogènes. Une explication possible, qui s’appuie sur un modèle théorique, est que le trading à grande vitesse augmente la dispersion des cotations de change, qui en retour accroît le temps nécessaire pour les traders pour traiter l’information contenue dans les cotations, rendant de fait le marché moins réactif à de nouvelles informations macroéconomiques et financières. Cette thèse de doctorat propose une nouvelle façon de penser et de mesurer l’impact du progrès technologique sur les marchés financiers. La première contribution est d’utiliser le réseau sous-marin des câbles à fibre optique comme choc technologique exogène et de mesurer son impact sur la géographie des marchés des changes et la volatilité. La seconde contribution est de montrer le lien entre trading à grande vitesse, dispersion des cotations et efficience des marchés, en utilisant l’entropie des cotations comme mesure du temps nécessaire pour traiter l’information contenue dans les prix et en comprendre l’impact sur l’efficience de marchéThis PhD dissertation is a collection of three essays on how technology has been shaping financial markets, using as a case study the foreign exchange market. The first chapter investigates the impact of technological innovations on the geography of the foreign exchange market. It uses as a proxy for exogeneous technological changes the connection of countries to submarine fiber-optic cables. The estimates of this chapter suggest that technology contributes to concentrating foreign exchange trading in an handful of financial centers. The second chapter studies the impact of technology on the reaction of foreign exchange markets to macroeconomic announcements. It shows that the development of Information and Communication Technologies dampens foreign exchange markets volatility. Finally, the third chapter shows that fast trading dampens market reaction to new macroeconomic information. One possible explanation, based on a theoretical model, is that fast traders increase the dispersion in exchange rate quotes, i.e. the time traders need to process new information about market prices; in turn, entropy dampens the market’s reaction to macro news. This PhD dissertation provides a new way to measure and conceptualize technological progress with regards to financial markets. The first contribution is to treat the network of submarine fiber optic cables as an exogenous technological shock to investigate the impact of technology on the geography of foreign exchange trading and on volatility. The second contribution is to show that patterns in the distribution of quotes matters in the context of fast trading. The concept of entropy in exchange rate quotes is used to characterize how fast information diffuses on financial markets and thereby to assess the implications of fast trading on market efficiency
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Hatzidakis, Fokion. "Multichannel data transmission through a fiber optic cable." Thesis, 1987. http://hdl.handle.net/10945/22375.
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Chen, Guo Hsiang, and 陳國祥. "The safety study of the fiber optic cable works." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/88286751053733671614.
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碩士國立雲林科技大學
環境與安全工程系碩士班
94
ABSTRACT With the extremely superior transmission characteristic, the optical fiber cable already widespread application and substitutes for the traditional copper in the correspondence transmission gradually, this study is expected to determine the result of understanding degree of the project personnel to their work content and try to figure out the more safety and ideal way in construction of the optical fiber communications. The most important motive in this article are the unexpected disaster or damage prevention correspond with occupational safety and health management and approach to build a safer environment for the workers. On hand of the investigation in safety and health cognition of the operating personnel, we used the questionnaire survey method and completed 243 questionnaires that based on sampling the worker who are the personnel in mainly 7 domestic telecommunication cooperation, include their basic information, safety and health custom and manner, personal protect equipment, and cognition of safety and health. The study knows the following result: (1) The enterprise has the faultless plan in work content with the safety equipment, but has not provided the optical fiber cable worker with the security lecture or training. (2)The staff don’t bear in mind the correct concept about guardian so they reluctant to wear protect equipments. (3)The operators are apt to pay less attention of the safety for low dangerous level of working environment.(4)The senior staff is likely to be lack of recognition. Therefore, we suggest enterprise should carry out on-job training program as well as the regulation so as to avoid any physical injury.
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Liu, Chu-Yan, and 劉郡晏. "The Study of Cable-Stayed Bridges Using Ambient Cable Vibration Measurements from Fiber Optic Sensors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/78296840868242063627.
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碩士雲林科技大學
營建工程系碩士班
96
Primary force-transmitting members of the whole cable-stayed bridge , it can directly reflecting the dynamic characteristics and health condition of the total bridge system. vibration measurements site easy and maneuverability so usually to used Ambient cable vibration measurements , but it can’t using to long-time measurements. So we are using the optical fiber sensors to measurements cable-stayed bridges vibration. It has single point joint two or more sensor , we measurement Chi-Lue Cable-Stayed Bridges with velocity sensor to prove optical sensor can used to measurements Cable-Stayed Bridges. So we go to Ma-Zu Cable-Stayed Bridges measurement single tendon , find different phenomenon with Chi-Lue Cable-Stayed Bridges , Single tendon we can see two different frequency , another one same the velocity sensors , it’s whole cable frequency. Another one is single tendon’s frequency. We used SAP2000 software analysis find the result can prove the measurements phenomenon. Prove before measurements new discovery.
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Li, Meng-Hua, and 李孟樺. "Research on Fiber-Optic Cable of Manufacturing Process Prediction and Optimization Models." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/04245779305007390897.
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Miller, Stuart Robert. "Dynamic programming based approach to scheduling in the fiber optic cable industry." 2003. http://www.lib.ncsu.edu/theses/available/etd-05142003-011628/unrestricted/etd.pdf.
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Peill, Nicola Joy. "Fiber-optic bundled array cable reactors for heterogeneous photocatalysis and waste stream remediation." Thesis, 1997. https://thesis.library.caltech.edu/175/1/Peill_nj_1997.pdf.
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NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
Application of semiconductor photocatalysis in a fixed-bed fiber-optic bundled array cable reactor (OFR) for the purification of contaminated water is investigated in this thesis. An optical fiber cable is employed as a means of light transmission and distribution to solid-supported TiO2. The system is designed for remote delivery of light to the photocatalyst, to allow for measurement of light fluxes for direct determination of quantum yields and for reuse of the reactor to test various coatings and light input angles, and to minimize possible heat build-up and delamination problems.
Experiments are carried out to determine the operational factors affecting the chemical efficiency of the OFR system. The uniformity and extent of light propagation down the fiber, the degree of light absorption by the TiO2 coating, the fiber diameter, the input light intensity, and the ability of the chemical substrates to diffuse into the TiO2 coating are determined to be important parameters. In addition, a TiO2 coating that minimizes the interfacial surface area of the quartz core and TiO2 particles and operation with incident irradiation angles near 90° enhance light propagation down the fibers. Relative quantum efficiencies in the OFR are found to be comparable to slurry-phase photochemical reaction systems.
The OFR is shown to effectively degrade several model chemical contaminants such as pentachlorophenol (PCP), 4-chlorophenol (4CP), dichloroacetate (DCA), and oxalate (OX) under varying reaction conditions. Relatively high quantum efficiencies of [...] = 0.010, 0.015, 0.08, and 0.17, respectively, and complete mineralization to CO2, H2O and HCl are observed.
When iron(III)-doped quantum-sized (Q) TiO2 (Fe/Q-TiO2) is used as a photocatalytic coating, the extent of linear light transmission in a single fiber is doubled relative to Degussa P25. However, the Fe/Q-TiO2 coating is found to have inferior light absorption properties and chemical reactivity leading to lower relative quantum efficiencies.
A concentrating, solar powered prototype OFR is designed and tested. Photoefficiencies with sunlight were comparable to that achieved with a Xe-arc source. Lower light intensity-to-photocatalytic surface area ratios result in increased relative quantum efficiencies.
A mathematical model of a fiber-optic bundled array reactor system is developed using Langmuir-Hinshelwood kinetics and compared to experimental data. A global quantum efficiency, [...], is defined and used as a model fitting parameter. It incorporates reaction parameters such as the absorbed light intensity, the intrinsic rate constant, and the effects of other adsorbed reactants and reaction intermediates. An empirical term to describe the radiation field within the coated fiber is derived and normalized by the coating photocatalyst particle concentration to account for the inverse relationship between the absorbed light intensity and the reaction quantum efficiency. The [...] is determined to be independent of the absorbed light intensity and calculated values are in excellent agreement with experimental values.
An analysis of conventional and advanced remediation technologies is performed (Appendix). The chemistry and engineering behind advanced oxidation systems is reviewed, and a means of technical evaluation and comparison is presented. The "electrical energy per order," or EEO is defined as the electrical energy required to reduce the concentration of a given pollutant by one order of magnitude in 1000 gal of water. The EEO can be used to compare the efficacy of remediation technologies with other AOT's and conventional systems for a particular cleanup application.
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Cheng, Kuang-Yu, and 鄭光佑. "Application responded surface method combined with genetic algorithm model building fiber-optic cable manufacturing process optimization study." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19699407774087635045.
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碩士國立勤益科技大學
工業工程與管理系
99
The development of optical fiber communication is mainly used to replace copper to increase communication capacity and distance, so the use of fiber with copper as necessary, to adapt to a variety of harsh environments. Without the protection of the fiber, not only fragile easily damaged and does not apply to the general lines of construction methods, it is necessary to protect the optical collection and add a variety of coating layer made of "fiber". The skin contraction rate of fiber optic cable manufacturing, normally used to define the key quality is good or bad. Product life cycle has progressed rapidly and manufacturing technology, the rapid changes in product quality and process improvement have become the industry competition the primary issue, and with trial and error and past experience or technical manuals, selected processing parameters, not only difficult to control the processing quality, also spent a lot of time and cost invisibly. Therefore, the requirements of manufacturing efficiency and processing quality, to examine in advance the results of predictive models to master processing, and processing parameters to solve the optimization problem are indeed necessary. In this study, the use of Six Sigma approach to improving the step DMAIC five stages to cross-border optical connection giant fiber processing process of empirical research, build cable jacket shrinkage improvement in process capability and predictable process optimization models, research methods combined with response surface methodology, genetic algorithms and statistical process control; using Six Sigma techniques to identify cable jacket shrinkage process critical factor (Key Factors) with standard range, by response surface methodology of the experimental configuration, and then apply response surface methodology (Respond Surface Method), referred to as the main factor to assess their future RSM, presented within the standard of quality characteristics, to identify process parameters combinations in the RSM analysis module in the standard of the best parameter combination to the simultaneous analysis was the best technology, but when the results of the analysis the total expected value of D is not ideal, this study attempts to further optimize by genetic algorithms as a search module, the genetic algorithm process, to the maximum fitness can search for the best processing parameters of fiber-optic cable, for practical enhance the quality of planning and decision-making reference to a reference basis.
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"A Novel Methodology To Classify The ADSS Cable Ranking." Master's thesis, 2011. http://hdl.handle.net/2286/R.I.9426.
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abstract: All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used over these ADSS cables. These dampers are installed near the armor rods, where the presence of leakage current and dry band activity is more. The effect of dampers on dry band activity is investigated by conducting experiments on ADSS cable and dampers. Observations made from the experiments suggest that the hydrophobicity of the cable and damper play a key role in stabilizing dry band arcs. Hydrophobic-ity of the samples have been compared. The importance of hydrophobicity of the samples is further illustrated with the help of simulation results. The results indi-cate that the electric field increases at the edges of water strip. The dry band arc-ing phenomenon could thus be correlated to the hydrophobicity of the outer sur-face of cable and damper.Dissertation/Thesis
M.S. Electrical Engineering 2011
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Sayde, Chadi. "Improving soil water determination in spatially variable field using fiber optic technology and Bayesian decision theory." Thesis, 2012. http://hdl.handle.net/1957/28778.
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Achieving and maintaining sustainability in irrigated agriculture production in the era of rapidly increasing stress on our natural resources require, among other essential actions, optimum control and management of the applied water. Thus, a significant upgrade of the currently available soil water monitoring technologies is needed. The primary goal of this work was to reduce the uncertainties of spatially variable soil water in the field. Two approaches are suggested: 1) The Bayesian decision model that implicitly accounts for spatial variability at minimal cost based on limited field data, and 2) The Actively Heated Fiber Optic (AHFO) method that explicitly accounts for spatial variability with high sampling density at relatively low cost per measurement point.
The Bayesian decision model uses an algorithm to integrate information embodied in independent estimates of soil water depletion to derive a posterior estimation of soil
water status that has the potential to reduce the risk of costly errors in irrigation scheduling decisions. The sources of information are obtained from an ET based water balance model, soil water measurements, and expert opinion. The algorithm was tested in a numerical example based on a field experiment where soil water depletion measurements were made at 43 sites in an agricultural field under center pivot irrigation. The results showed that the estimates of the average soil water depletion in the field obtained from the posterior distributions of soil water depletion proved to outperform simple averaging of n soil water depletion measurements, up to n = 35 measurements. For n< 3, the model also provided a 39% average reduction in risk of error derived from non-representative measurements.
The AHFO method observes the heating and cooling of a buried fiber optic (FO) cable through the course of a pulse application of energy as monitored by a distributed temperature sensing (DTS) system to reveal soil water content simultaneously at sub-meter scale along the FO cable that can potentially exceeds kilometers in length. A new and simple interpretation of heat data that takes advantage of the characteristics of FO temperature measurements is presented. The results demonstrate the feasibility of AHFO method application to obtain <0.05 m³m⁻³ error distributed measurements of soil water content under laboratory controlled conditions. The AHFO method was then tested under field conditions using 750 m of FO cables buried at 30, 60, and 90 cm depths in agricultural field. The calibration curve relating soil water content to the thermal response of the soil to a heat pulse was developed in the lab. It was successively applied to the 30 and 60 cm depths cables, while the 90 cm depth cable
illustrated the challenges of soil heterogeneity for this technique. The method was used to map with high spatial (1m) and temporal (1hr) resolution the spatial variability of soil water content and fluxes induced by the non-uniformity of water application at the surface.Graduation date: 2012