Thesis (M.S.)--Ohio State University, 2007. / Includes bibliographical references (leaves 148-152). Available online via OhioLINK's ETD Center

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-04Bitstream added on 2014-06-13T19:55:28Z : No. of bitstreams: 1 barrosjunior_jfc_me_guara.pdf: 1817218 bytes, checksum: e69e6e1e02780c3a6051459aeafb5bfe (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Devido ao aumento da demanda no mercado de tubos de condução, houve a necessidade de um incremento na velocidade de soldagem na etapa interna, que possui uma defasagem em média de 10 pol./min em relação a etapa externa. Isto porque o processo trabalha com três arames na etapa interna pelo método de soldagem por arco submerso, enquanto o externo, com quatro arames. Como ação, a etapa interna foi aumentada para quatro arames a fim de equalizar a velocidade destas etapas. Porém, há a necessidade de se definir qual será a velocidade limite. Assim, neste estudo aplicado a tubos de condução, segundo a norma API 5L e grau X70, inicialmente, foi feita uma retirada de amostra de macrografia da solda para avaliar o alinhamento entre o cordão de solda interno e o externo e a sobreposição entre os cordões de solda. Posteriormente, foi realizada na porção da solda interna, os ensaios de dureza pelo método de Vickers e ensaio de impacto pelo método de Charpy, obtendo-se as curvas de transição. Com o auxilio do gráfico t 8/5 foram definidos os limites de velocidade de soldagem para aplicar na EPS (Especificação do Procedimento de Soldagem). Pode-se obter maior confiabilidade na decisão da variável velocidade de soldagem que irá contemplar na EPS e com menor quantidade de retirada de amostras, através dos limites e valores máximos e mínimos da dureza. Desta forma, a prática mostrou-se satisfatória e os resultados mostraram a faixa de velocidade para atender com segurança os limites de valores das propriedades mecânicas solicitados pela norma API 5L. / Due to increased in the demand for conduction pipes in the market, there has been a necessity to increase the welding speed in the internal phase, which has an average discrepancy of 10 inches / min when compared to the external phase. It happens because the process works with three wires in the internal step method following the submerged arc welding, while the external one uses four wires. As a consequence the internal step was increased to four wires in order to equalize the speed of these steps. There are need to define what the top speed limit is. Therefore this study is applied to conduction pipes, according to API 5L grade X70 and, at first, a sample was drawn from Macrographic solder to assess the alignment between the weld and the inside and the outside overlap between the weld. This was followed by the analyses of the inside portion of weld, the hardness test method for Vickers and impact test Charpy method, obtaining the curves of transition. With the help of graphic t 8 / 5 speed limits were set to apply to welding in WPS (Welding Procedure Specification). It is possible to achieve more reliability in the decision about variable welding speed that will include the WPS and the least amount of sampling through the limits and minimum and maximum hardness. Thus the practice was satisfactory and the results showed that the speed range meets the safety limits of values of the mechanical properties required by the standard API 5L.

This thesis is concerned with the modelling of electrical machines for use in variable-speed drives. Even when the structure of the model of the machine is known values have to be assigned to the parameters. In addition, it is usual for only some of the state variables to be measured, any others needed being estimated using the model. The present work is a study of methods of making on-line estimates of the model parameters, using a reduced number of measured states. To offer high level dynamic torque control the non-measured state variables must be indirectly estimated to a high degree of accuracy throughout the complete range of operating conditions. The state estimator is generally classified with respect to the degree of structural complexity. At one end of the spectrum the model is constructed with a very high level of complexity in order to describe fully the system during any operating conditions. Because of this structural accuracy, the model parameters can be fixed prior to running the machine under normal conditions. However, this scheme suffers from a high computational burden in the state estimation process, and requires sophisticated commissioning strategies in order to permit the complete identification of the relatively large parameter set. The alternative is to use a simpler model structure and update the parameters with sufficient speed on-line in order to compensate for the inherently larger structural error. In this thesis the latter method is considered and preferred, as it has a greater robustness to unforeseen system behaviour and is more compatible with existing control strategies. As a consequence of the simple estimator the identification scheme has to compensate for the considerable structural errors. To this end the strategy of full parameter set identification is described. Work has also been done, and is presented, concerning on-line parameter identification using genetic optimisation techniques, which are shown to be well suited to this type of problem. The first studies of modelling and parameter extraction were concerned with dc machines, for these were thought to be simpler to model and to understand. DC machines are also different, in that the simple model includes mechanical parameters, and so represents a more complete system than the models of the ac machine studied later. A number of standard, enhanced and novel parameter identification methods are analysed and implemented on a practical machine and drive test bench. Also included were state estimators, intended to permit speed-sensorless control; however, the limitations on the experimental rig, based as it was around a commercially available drive, meant that some of the testing had to be done by running the estimator off-line, using data recorded from actual runs as the input. The thesis is primarily concerned with the induction machine and specifically the parameters required to permit field and speed sensorless rotor field orientated vector control. Sufficient work was done to allow a preliminary experimental comparison of a number of algorithms. At this stage it appears that several of these could be developed into successful drives, the precise choice depending on the specific application.

This thesis constitutes a general survey and a study of significant extensions to the usual conventional satellite radar altimetry. Historically radar altimeter has been configured to the measurement of mean sea level. It is well known that other statistics such as Significant Wave Height (SWH) and wind speed are in principle recoverable from the radar echo and these are currently of great interest. It has been the aim in this thesis to optimize such measurements, for a general meteorological application, with less interest shown in absolute measurement of sea level. Current technology makes possible a total Earth survey using a constellation of small satellites, covering the entire Earth sea surface with short revisit time. Such solutions necessitate less cost, lower power, and less precise attitude control than the scientific satellites used hitherto. The purpose of this thesis is to present a novel two mode radar altimeter for sea state monitoring. SWH is still measured by conventional high-resolution mode, which is not sensitive to off-nadir pointing. An additional novel low-resolution mode is proposed for wind speed measurement. By using this mode, wind speed measurement is much more robust to pointing error than by using conventional high-resolution mode. An improved wind speed measurement can be achieved by using a cost effective small satellite. Some considerable time was also spent on incorporating SAR (Synthetic Aperture Radar) into altimetry techniques to improve the signal to noise ratio. For sea state monitoring the improvements are relatively disappointing, although greater improvement are expected for ice sheet monitoring.

Road traffic accidents continue to be a public health problem and are a global issue due to the huge financial burden they place on families and society as a whole. Speed has been identified as a major contributor to the severity of traffic accidents and there is the need for better speed management if road traffic accidents are to be reduced. Over the years various measures have been implemented to manage vehicle speeds. The use of speed cameras and vehicle activated signs in recent times has contributed to the reduction of vehicle speeds to various extents. Speed cameras use punitive measures whereas vehicle activated signs do not so their use depends on various factors. Engineers, planners and decision makers responsible for determining the best place to mount a speed camera or vehicle activated sign along a road have based their decision on experience, site characteristics and available guidelines (Department for Transport, 2007; Department for Transport, 2006; Department for Transport, 2003). These decisions can be subjective and indications are that a more formal and directed approach aimed at bringing these available guidelines together in a model will be beneficial in making the right decision as to where to place a speed camera or vehicle activated sign is to be made. The use of optimisation techniques have been applied in other areas of research but this has been clearly absent in the Transport Safety sector. This research aims to contribute to speed reduction by developing a model to help decision makers determine the optimum location for a speed control device. In order to achieve this, the first study involved the development of an Empirical Bayes Negative Binomial regression accident prediction model to predict the number of fatal and serious accidents combined and the number of slight accidents. The accident prediction model that was used explored the effect of certain geometric and traffic characteristics on the effect of the severity of road traffic accident numbers on selected A-roads within the Nottinghamshire and Leicestershire regions of United Kingdom. On A-roads some model variables (n=10) were found to be statistically significant for slight accidents and (n=6) for fatal and serious accidents. The next study used the accident prediction model developed in two optimisation techniques to help predict the optimal location for speed cameras or vehicle activated signs. Pattern Search and Genetic Algorithms were the two main types of optimisation techniques utilised in this thesis. The results show that the two methods did produce similar results in some instances but different in others. Optimised results were compared to some existing sites with speed cameras some of the results obtained from the optimisation techniques used were within proximity of about 160m. A validation method was applied to the genetic algorithm and pattern search optimisation methods. The pattern search method was found to be more consistent than the genetic algorithm method. Genetic algorithm results produced slightly different results at validation in comparison with the initial results. T-test results show a significant difference in the function values for the validated genetic algorithm (M= 607649.34, SD= 1055520.75) and the validated pattern search function values (M= 2.06, SD= 1.17) under the condition t (79) = 5.15, p=0.000. There is a role that optimisation techniques can play in helping to determine the optimum location for a speed camera or vehicle activated sign based on a set of objectives and specified constraints. The research findings as a whole show that speed cameras and vehicle activated signs are an effective speed management tool. Their deployment however needs to be carefully considered by engineers, planners and decision makers so as to achieve the required level of effectiveness. The use of optimisation techniques which has been generally absent in the Transport Safety sector has been shown in this thesis to have the potential to contribute to improve speed management. There is however no doubt that this research will stimulate interest in this rather new but high potential area of Transport Safety.

In order to achieve energy savings for belt conveyor system, speed control provides one of the best solutions. Most of the traditional belt conveyors used in the industries are based on constant speed for all operational times. Due to the need and advancements in technology, Variable Frequency Drives (VFD) are employed in industries for a number of processes. Passive Speed Control was previously suggested for the proper utilization of VFD to make belt conveyor systems more power e- cient with increased life expectancy and reduced environmental eects including the noise reduction caused by constant speed of operation. Due to certain conditions and nature of operation of belt conveyor systems, it is not desirable to use Passive Speed control where feeding rate is random. Due to the extreme non-linearity of the random feeding rate, an Active speed control for VFD is desired which adjusts belt speed according to the material loading. In this thesis an Active Speed control for VFD is proposed that can achieve energy and cost ecient solutions for belt conveyor systems as well as avoiding half-lled belt operations. The aim of this thesis work is primarily to determine reliability and validity of Active Speed Control in terms of power savings. Besides achieving power savings, it is also necessary to check the economic feasibility. A detailed study is performed on the feasibility of Active Speed Control for random feeding rate according to industrial requirements. Due to the random and non-linearity of the material loading on the belt conveyor systems, a fuzzy logic algorithm is developed using the DIN 22101 model. The developed model achieves Active Speed Control based on the feeding rate and thereby optimizes the belt speed as required. This model also overcomes the risks of material spillage, overloading and sudden jerks caused due to unpredicted rise and fall during loading. The model conserves 20- 23% of the total power utilized compared to the conventional conveyor systems in use. However it is noticed that the peak power of conventional conveyor belt systems is up to 16% less compared to the proposed model. If implemented in dierent industries, based on the operational time and total consumption of electricity, the proposed Active speed control system is expected to achieve economic savings up to 10-12 % .

The purposes of the present study were to determine which aspects of processing speed are affected in Attention-Deficit/Hyperactivity Disorder (ADHD) and which cognitive and motoric skills predict processing speed performance. Results indicated that children with ADHD performed slower than controls on perceptual and visual-motor speed measures (Symbol Search and Coding) but not on reaction time or cognitive speed measures (Simple Reaction Time and Decision Speed). Those with ADHD-PI were particularly affected. Verbal working memory predicted Symbol Search, Coding and Decision Speed performance, while graphomotor speed predicted Coding, and fine motor dexterity predicted Decision Speed. Thus, children with ADHD may struggle on tasks with greater perceptual and visual-motor demands, which may be related to the inattention dimension. Furthermore, this study provides further evidence for the relationship between working memory and processing speed, especially central executive involvement in processing speed. Other theoretical and clinical implications are discussed for classroom and clinic interventions.

AN ABSTRACT OF THE THESIS OF ROHIT JOGINEEDI, for the Master of Science degree in Mechanical Engineering and Processes, presented on 11/06/2017, at Southern Illinois University Carbondale. TITLE: DEVELOPMENT OF COMPARATIVE WEAR TEST FOR ASTM G75 STANDARD MAJOR PROFESSOR: Dr. Peter Filip Industries related to tribology field invest huge amounts in testing products they handle. Most of their budget goes into running tests on corresponding friction, wear or lubrication testing instruments. These tests are observed to be consuming more time with an increase in operational costs. This gained importance among industries for developing economical testing methods designed to run on one or more machines to study tribological conditions. As friction and wear are system properties, change in system variables like distance, velocity, time and area can have notable impact on those properties. This paper discusses about various approaches to develop comparative test on sub scale testers for ASTM G75 standard. Scaling Laws of Physics and comparison of wear mode are two approaches used in this paper to justify the comparative test developed for ASTM G75 on a bench top tester developed by Bruker. Results from the ASTM G75 standard and the UMT are compared and concluded that scaling strategies cannot be used to replicate the standard test methods on sub scale testers but comparison of wear mode could help. This proposed comparative test for ASTM G75 is observed to have lower operational costs thereby decreasing the amount of investment on testing friction or wear products in an industry.

abstract: The market for high speed camera chips, or image sensors, has experienced rapid growth over the past decades owing to its broad application space in security, biomedical equipment, and mobile devices. CMOS (complementary metal-oxide-semiconductor) technology has significantly improved the performance of the high speed camera chip by enabling the monolithic integration of pixel circuits and on-chip analog-to-digital conversion. However, for low light intensity applications, many CMOS image sensors have a sub-optimum dynamic range, particularly in high speed operation. Thus the requirements for a sensor to have a high frame rate and high fill factor is attracting more attention. Another drawback for the high speed camera chip is its high power demands due to its high operating frequency. Therefore, a CMOS image sensor with high frame rate, high fill factor, high voltage range and low power is difficult to realize. This thesis presents the design of pixel circuit, the pixel array and column readout chain for a high speed camera chip. An integrated PN (positive-negative) junction photodiode and an accompanying ten transistor pixel circuit are implemented using a 0.18 µm CMOS technology. Multiple methods are applied to minimize the subthreshold currents, which is critical for low light detection. A layout sharing technique is used to increase the fill factor to 64.63%. Four programmable gain amplifiers (PGAs) and 10-bit pipeline analog-to-digital converters (ADCs) are added to complete on-chip analog to digital conversion. The simulation results of extracted circuit indicate ENOB (effective number of bits) is greater than 8 bits with FoM (figures of merit) =0.789. The minimum detectable voltage level is determined to be 470μV based on noise analysis. The total power consumption of PGA and ADC is 8.2mW for each conversion. The whole camera chip reaches 10508 frames per second (fps) at full resolution with 3.1mm x 3.4mm area. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

The concept of reciprocal acoustical travel-time measurements as a means of determining path-averaged currents is well established. We have designed an instrument to exploit this principle in studies of the boundary layer just beneath the arctic ice cover. Such measurements are of interest both because of the opportunity provided for comparison with the more commonly acquired point measurements and because of a particular configuration allowing determination of average vorticity, which cannot be achieved with the traditional approach; in addition, their unprecedented sensitivity allows detection of phenomena not observable with traditional sensors. The acoustical instrument was deployed during the spring of 1989 in the sub-ice boundary layer of the Eastern Arctic in order to measure turbulence, path-averaged horizontal current, and relative vorticity. A triangular acoustic array of side 200 m was used to obtain reciprocal transmission measurements at 132 kHz, at 8, 10 and 20 m beneath an ice floe. Pseudo-random coding and real-time signal processing provided precise acoustic travel time and amplitude for each reciprocal path. Mean current along each acoustic path is proportional to travel time difference between reciprocal transmissions. Horizontal velocity normal to the acoustic paths is measured using scintillation drift. The instrument measures horizontal circulation and average vorticity relative to the ice, at length scales characteristic of high frequency internal waves in the region. The rms noise level of the measurements is less than 0.1 mm/s for velocity measurements and 0.01 for vorticity, averaged over one minute. Except near the mechanical resonance frequency of the moorings, the measurement accuracy is limited by multipath interference. Path-averaged horizontal velocity is compared to point measurements and marked differences are observed due to local anomalies of the flow field. The integral measurement of current is particularly sensitive to the passage of internal waves that have wavelengths longer than the horizontal separation of the transducers. A comparison of horizontal velocity at two depths in the boundary layer shows good coherence at internal wave frequencies and some attenuation as the ice is approached. Relative vorticity at internal wave length scales is dominated by horizontal shear caused by flow interaction with ice topography and not by planetary vorticity. Reciprocal acoustical travel time measurements over paths of several hundred meters can be used to probe the statistical behaviour of turbulent velocity fine structure in the ocean. For homogenous isotropic flows, and for long measuring baselines, an analytic expression relating line-averaged and point measurements of velocity is derived. Anisotropic and inhomogeneous flows are also considered. Correction formulas for the spatial and temporal variability of advection velocity along the measuring baseline are obtained. Practical limitations are established, and experimental data from the arctic boundary layer beneath ice is compared with the theory. A new remote sensing technique for measuring turbulent kinetic energy dissipation rate is suggested. / Graduate