The Hayes Coastal Engineering Laboratory is a new laboratory with two water basins: a 45.72-meters long, 3.66 meters wide and 3.06 meters deep Tow Tank with sediment pit for dredging and current flow studies, and a 36.58 meters long, 22.86 meters wide and 1.22 meters deep 3D Wave Basin for coastal wave studies. In order to assess the capabilities of the lab a series of tests were done in both tanks. Hydrodynamic tests in the Tow Tank using a Micro Acoustic Doppler Velociometer measured current flow in the tank and assessed the efficacy of different filters to stabilize flow patterns. A concrete dam structure installed near the reversed diffusers most effectively stabilized flow of all the configurations tested. Wave tests were conducted in the 3D Wave Basin with the newly-installed 48 paddle Rexroth wave generator at 0.5 and 1.0 meter water depths using wired and wireless capacitance wave gauges. These tests measured characteristics of the generated waves and reflection from the rubble-mound beach. In addition, initial testing of the Active Reflection Absorber (ARA) system was done. Correlating the wave data to the theoretical wave being produced showed that with water depth of 0.5 meters the 0.1 meter waves were well-formed, but the 0.2 meter waves showed energy loss and lower correlation. The results from one meter water depth wave tests showed good formation of 0.2 meter waves. In nearly all wave tests with pool buoys installed the waves were better formed with good correlation and a better fitting power spectrum. The beach reflection was within the expected value range, being ten percent and below for most tests. ARA, while operational, needs to be further tuned to find the settings that will increase its effectiveness.

The Hayes Coastal Engineering Laboratory is a new laboratory with two water basins: a 45.72-meters long, 3.66 meters wide and 3.06 meters deep Tow Tank with sediment pit for dredging and current flow studies, and a 36.58 meters long, 22.86 meters wide and 1.22 meters deep 3D Wave Basin for coastal wave studies. In order to assess the capabilities of the lab a series of tests were done in both tanks. Hydrodynamic tests in the Tow Tank using a Micro Acoustic Doppler Velociometer measured current flow in the tank and assessed the efficacy of different filters to stabilize flow patterns. A concrete dam structure installed near the reversed diffusers most effectively stabilized flow of all the configurations tested. Wave tests were conducted in the 3D Wave Basin with the newly-installed 48 paddle Rexroth wave generator at 0.5 and 1.0 meter water depths using wired and wireless capacitance wave gauges. These tests measured characteristics of the generated waves and reflection from the rubble-mound beach. In addition, initial testing of the Active Reflection Absorber (ARA) system was done. Correlating the wave data to the theoretical wave being produced showed that with water depth of 0.5 meters the 0.1 meter waves were well-formed, but the 0.2 meter waves showed energy loss and lower correlation. The results from one meter water depth wave tests showed good formation of 0.2 meter waves. In nearly all wave tests with pool buoys installed the waves were better formed with good correlation and a better fitting power spectrum. The beach reflection was within the expected value range, being ten percent and below for most tests. ARA, while operational, needs to be further tuned to find the settings that will increase its effectiveness.

The work described in this thesis tested the feasibility of using a towed array of hydrophones to: 1. localise sources of underwater acoustic noise radiated by the towvessel, 2. determine the absolute amplitudes of these sources, and 3. determine the resulting far-field acoustic signature of the tow-vessel. The concept was for the towvessel to carry out a U-turn manoeuvre so as to bring the acoustic section of the array into a location suitable for beamforming along the length of the tow-vessel. All three of the above were shown to be feasible using both simulated and field data, although no independent field measurements were available to fully evaluate the accuracy of the far-field acoustic signature determinations. A computer program was written to simulate the acoustic signals received by moving hydrophones. This program had the ability to model a variety of acoustic sources and to deal with realistic acoustic propagation conditions, including shallow water propagation with significant bottom interactions. The latter was accomplished using both ray and wave methods and it was found that, for simple fluid half-space seabeds, a modified ray method gave results that were virtually identical to those obtained with a full wave method, even at very low frequencies, and with a substantial saving in execution time. A field experiment was carried out during which a tug towing a 60-hydrophone array carried out a series of U-turn manoeuvres. The signals received by the array included noise radiated by the tow-vessel, signals from acoustic tracking beacons mounted on the tow-vessel, and transient signals generated by imploding sources deployed from a second vessel. / Algorithms were developed to obtain snapshots of the vertical plane and horizontal plane shapes of the array from the transient data and to use range data derived from the tracking beacon signals to track the hydrophones in the horizontal plane. The latter was complicated by a high proportion of dropouts and outliers in the range data caused by the directionality of the hydrophones at the high frequencies emitted by the beacons. Despite this, excellent tracking performance was obtained. Matched field inversion was used to determine the vertical plane array shapes at times when no transient signals were available, and to provide information about the geoacoustic properties of the seabed. There was very good agreement between the inversion results and array shapes determined using transient signals. During trial manoeuvres the array was moving rapidly relative to the vessel and changing shape. A number of different array-processing algorithms were developed to provide source localisation and amplitude estimates in this situation: a timedomain beamformer; two frequency-domain, data independent beamformers; an adaptive frequency-domain beamformer; and an array processor based on a regularised least-squares inversion. The relative performance of each of these algorithms was assessed using simulated and field data. Data from three different manoeuvres were processed and in each case a calibrated source was localised to within 1 m of its known position at the source's fundamental frequency of 112 Hz. / Localisation was also successful in most instances at 336 Hz, 560 Hz and 784 Hz, although with somewhat reduced accuracy due to lower signal to noise ratios. Localisation results for vessel noise sources were also consistent with the positions of the corresponding items of machinery. The estimated levels of the calibrated source obtained during the three manoeuvres were all within 4.1 dB of the calibrated value, and varied by only 1.3 dB between manoeuvres. Results at the higher frequencies had larger errors, with a maximum variation of 3.8 dB between serials, and a maximum deviation from the calibrated value of 6.8 dB. An algorithm was also developed to predict the far-field signature of the tow-vessel from the measured data and results were produced. This algorithm performed well with simulated data but no independent measurements were available to compare with the field results.

This study investigates the structures of flow field in the mouth of Kao-Ping River, southwest Taiwan. The data used in this study are collected from several cruises of field observations using research vessel OR3 and fishing boats. Instruments deployed include bmADCP, sbADCP, towADCP, Aquadopp, CTD, XR420 and Seacat37. Spatial and temporal variations of flow, sea level, temperature and salinity data are sampled. The collected data are analyzed through harmonic analysis, low-pass filter and FFT. Results from previously study showed that cold water flowed eastward into the canyon during flood, and westward out of the canyon during ebb. This study shows that the canyon head is not the channel for bottom layer water to climb up into the shallow bank or the river (perhaps the bottom water climb up over shelf at the turning of the canyon 5 km offshore). The summaries are: (1)Water mass are moving around dominated by the oscillation M2 tidal current. There are 3 hours lag between sea level and flow. Maximum out canyon flow found at the peak of flood, while in canyon flow found at the low water. (2)The coastal surface water flows southeast during flood, and goes to northwest during ebb. (3)Tide current is the primary dynamic in the Kaoping River.During flood, lower temperature and higher salinity seawater is up river. During ebb, higher temperature and lower salinity is down the river. Amplitude of tidal current decreases with depth (likely due to bottom friction) at river mouth depth of 3 meters.

Thesis (M.S. in Management)--Naval Postgraduate School, December 2002. / Thesis advisor(s): David F. Matthews, Keebom Kang. Includes bibliographical references (p. 113-116). Also available online.

High-performance fibres such as carbon, glass and kevlar are very promising for aerospace applications because of their high strength, stiffness, impact damage and excellent fatigue life. The high cost of the prepreg materials such as pre-impregnated fibre tape/tow and fabrics, and limitations of existing manufacturing processes are a big challenge for the aerospace industry to meet increasing performance demands. Their benefits can only be achieved by using low cost materials and manufacturing methods. In the past three or four decades, there have been substantial technological developments, which are governed by the new materials and their associated manufacturing techniques. The production of carbon fibre is slow and capital intensive, therefore, carbon manufactures produce higher tow counts (number of filaments) to increase production through-put in order to reduce its cost. In other words, 12k carbon tow is much cheaper than 6k or 3k carbon tow. In many applications finer tows are desirable. In this thesis, a fully automated laser feedback tow splitting line has been developed to split higher tow counts (12k spool) into smaller tow counts (split into 6k spools) in order to produce low cost material. The quality of the split tows has been evaluated by recording the data online during the splitting process. The recorded data was later analysed by statistical tools. A four axis modular gantry robotic system has been developed at the University of Manchester in order to deposit dry fibres in a completely flexible manner. To facilitate robotic preforming, an end-effector and mould have been designed and developed in this research. The tow placement program was written in the CoDeSys software which is then uploaded into the motion controller to perform specific motions. The cross-ply laminates have been manufactured by the proposed robotic system using split 6k (produced by the tow splitting process) and original 12k carbon tows. Mechanical test of both composites (12k and split 6k) are presented. A tufting process has been developed and conducted by the robotic system in order to manufacture 3D preforms. The tufted composite was compared with 3D woven and stitched 2D broadcloth in terms of the tensile and interlaminar shear strength properties. X-ray tomography has been conducted to investigate preform geometrical variations of manufactured composites. In addition, preforming cost models have been developed for robotic fibre placement and 3D weaving.

By envisioning that the future broadband access networks have to support many bandwidth consuming applications, such as VoIP, IPTV, VoD, and HDTV, the integration of WiMAX and EPON networks have been taken as one of the most promising network architecture due to numerous advantages in terms of cost-effectiveness, massive-bandwidth provisioning, Ethernet-based technology, reliable transmissions, and QoS guarantee. Under the EPON-WiMAX integration, the development of a scheduling algorithm that could be channel-aware and queue-aware will be a great plus on top of the numerous merits and flexibility in such an integrated architecture. In this thesis, a novel two-level scheduling algorithm for the uplink transmission are proposed by using the principle of proportional fairness for the transmissions from SSs over the WiMAX channels, while a centralized algorithm at the OLT for the EPON uplink from different WiMAX-ONUs. The scheduler at the OLT receives a Report message from each WiMAX-ONU, which contains the average channel condition per cell, queues length, and head-of-line (HOL) delay for rtPS traffic. The EPON data frame is then scheduled based on these Report messages. Numerical results show that the proposed scheme could satisfy the end-to-end real-time QoS requirements. In addition, the centralized scheduler at the OLT can achieve high throughput in presence of traffic load variation.

By envisioning that the future broadband access networks have to support many bandwidth consuming applications, such as VoIP, IPTV, VoD, and HDTV, the integration of WiMAX and EPON networks have been taken as one of the most promising network architecture due to numerous advantages in terms of cost-effectiveness, massive-bandwidth provisioning, Ethernet-based technology, reliable transmissions, and QoS guarantee. Under the EPON-WiMAX integration, the development of a scheduling algorithm that could be channel-aware and queue-aware will be a great plus on top of the numerous merits and flexibility in such an integrated architecture. In this thesis, a novel two-level scheduling algorithm for the uplink transmission are proposed by using the principle of proportional fairness for the transmissions from SSs over the WiMAX channels, while a centralized algorithm at the OLT for the EPON uplink from different WiMAX-ONUs. The scheduler at the OLT receives a Report message from each WiMAX-ONU, which contains the average channel condition per cell, queues length, and head-of-line (HOL) delay for rtPS traffic. The EPON data frame is then scheduled based on these Report messages. Numerical results show that the proposed scheme could satisfy the end-to-end real-time QoS requirements. In addition, the centralized scheduler at the OLT can achieve high throughput in presence of traffic load variation.

Orientador: Osvair Vidal Trevisan / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-12T18:20:10Z (GMT). No. of bitstreams: 1 Marques_JoaoBoscoDias_M.pdf: 2275485 bytes, checksum: 7008d88db0703cad4c59a10ca5e7b368 (MD5) Previous issue date: 2008 / Resumo: Este trabalho disserta sobre a análise de teste transitório de produção e de crescimento de pressão em poço vertical sob condição de escoamento bifásico de óleo e gás. Os resultados obtidos são o fator de película e pontos das curvas das permeabilidades efetivas ao óleo e ao gás em função da saturação de óleo. A permeabilidade efetiva em função da saturação do óleo é obtida da combinação da permeabilidade efetiva em função da pressão de teste de poço com a solução de uma equação diferencial ordinária que relaciona a saturação do óleo com a pressão. Um dos métodos, denominado método p2, é desenvolvido a partir da representação da curva da função de pseudopressão, kro/(µoBo) versus a pressão de teste, por meio de duas linhas retas. O problema físico analisado consiste de um reservatório homogêneo operando a partir da pressão de bolha, água conata imóvel e efeitos de capilaridade e de gravidade desprezíveis. Os dados para validação dos métodos são obtidos com testes de poços realizados em modelos de reservatórios preparados num simulador comercial. O método p2 utiliza basicamente pontos e inclinações de retas de curvas típicas, construídas com dados de teste de poço, para determinar o fator de película e as curvas das permeabilidades efetivas aos fluidos. As curvas obtidas pelo método p2 são comparadas com as obtidas por outro método, chamado de método de determinação in situ / Abstract: This thesis provides an analysis of drawdown and buildup tests from vertical well under solution gas-drive conditions. The results obtained include the skin factor and the points of the effective permeability curves for the oil and gas as a function of oil saturation. The effective permeability as a function of oil saturation is the result of a combination of the effective permeability as a function of wellbore pressure and the solution of an ordinary differential equation which relates oil saturation to the pressure. One of the methods, named square-pressure method, is developed using two straight lines to approximate the curve of the pseudo-pressure function, kro/(µoBo) versus the wellbore pressure. The physical problem consists of a homogeneous reservoir operating from bubble-point pressure with immobile connate water, neglecting the capillarity and gravity effects. The data for the validation of the methods was obtained using well tests reservoirs models built in a commercial simulator. The p2 method basically utilizes the points and the straight lines slope of typical curves built from well test data to determinate the effective permeability curves and the skin factor. Then, the results of these curves are compared to those obtained with another method, named in situ determination method / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

The growing number of applications of composite materials in aerospace and naval structures along with advancements in manufacturing technologies demand continuous innovations in the design of composite structures. In the traditional design of composite laminates, fiber orientation angles are constant for each layer and are usually limited to 0, 90, and ±45 degrees. To fully benefit from the directional properties of composite laminates, such limitations have to be removed. The concept of variable-stiffness laminates allows the stiffness properties to vary spatially over the laminate. Through tailoring of fiber orientations and laminate thickness spatially in an optimal fashion, mechanical properties of a part can be improved. In this thesis, the optimal design of variable-stiffness fiber-reinforced composite laminates is studied using an emerging numerical engineering optimization scheme based on the cellular automata paradigm. A cellular automaton (CA) based design scheme uses local update rules for both field variables (displacements) and design variables (lay-up configuration and laminate density measure) in an iterative fashion to convergence to an optimal design. In the present work, the displacements are updated based on the principle of local equilibrium and the design variables are updated according to the optimality criteria for minimum compliance design. A closed form displacement update rule for constant thickness isotropic continua is derived, while for the general anisotropic continua with variable thickness a numeric update rule is used. Combined lay-up and topology design of variable-stiffness flat laminates is performed under the action of in-plane loads and bending loads. An optimality criteria based formulation is used to obtain local design rules for minimum compliance design subject to a volume constraint. It is shown that the design rule splits into a two step application. In the first step an optimal lay-up configuration is computed and in the second step the density measure is obtained. The spatial lay-up design problem is formulated using both fiber angles and lamination parameters as design variables. A weighted average formulation is used to handle multiple load case designs. Numerical studies investigate the performance of the proposed design methodology. The optimal lay-up configuration is independent of the lattice density with more details emerging as the density is increased. Moreover, combined topology and lay-up designs are free of checkerboard patterns. The lay-up design problem is also solved using lamination parameters instead of the fiber orientation angles. The use of lamination parameters has two key features: first, the convexity of the minimization problem guarantees a global minimum; second, for both in-plane and bending problems it limits the number of design variables to four regardless of the actual number of layers, thereby simplifying the optimization task. Moreover, it improves the convergence rate of the iterative design scheme as compared to using fiber angles as design variables. Design parametrization using lamination parameters provides a theoretically better design, however, manufacturability of the designs is not certain. The cases of general, balanced symmetric, and balanced symmetric with equal thickness layers are studied separately. The feasible domain for laminates with equal thickness layers is presented for an increasing number of layers. A restricted problem is proposed that maintains the convexity of the design space for laminates with equal thickness layers. A recursive formulation for computing fiber angles for this case is also presented. On the computational side of the effort, a parallel version of the present CA formulation is implemented on message passing multiprocessor clusters. A standard parallel implementation does not converge for an increased number of processors. Detailed analysis revealed that the convergence problem is due to a Jacobi type iteration scheme, and a pure Gauss-Seidel type iteration through a pipeline implementation completely resolved the convergence problem. Timing results giving the speedup for the pipeline implementation were obtained for up to 260 processors. This work was supported by Grant NAG-1-01105 from NASA Langley Research Center. Special thanks to our project monitor Dr. Damodar R. Ambur for his technical guidance. / Ph. D.