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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
381

A Projectile Subsystem in a Flight Simulation System

Hodson, Robert F. 01 January 1985 (has links) (PDF)
An overview of a flight simulation system is presented with a discussion of the system components and the interaction between functional units. The functions of each unit in the visual system are described. Specifically, the projectile subsystem portion of the visual system is presented in detail. A projectile subsystem executive structure is presented with capability of controlling projectile activation and deletion. Mathematical models for missiles with linear projected impact and proportional guidance are discussed. Ballistic projectile models with and without wind and drag considerations are developed. The mathematical equations for position and attitude calculations are given. Design considerations and implementation of algorithms are also presented with other system design trade-offs.
382

Synthetic Jet Actuator for Active Flow Control

Abdou, Sherif 11 1900 (has links)
A long aspect ratio synthetic jet is produced through an axial slit along part of the length of a cylinder. The jet is excited acoustically by a pair of loudspeakers mounted at the cylinder terminations. The study compares between the performance of two different slits with aspect ratios of 273 and 773. The comparison is based on the spanwise distribution of the mean jet velocity and phase between the jet velocity fluctuations and the excitation signal. Three different frequencies and amplitudes are used to excite the speakers covering the range of frequencies used in the control application. For both cases studied the mean centerline velocity of the jet increases with increasing the amplitude of the exciting signal, but decreases with increasing its frequency. Moreover, velocity deficits of up to 30% are evident as the midspan of the cylinder is approached from either end. Similar trends are also observed for the centerline phase distributions of the velocity fluctuations, with deficits of up to 130°. However, it is observed that for the long slit case the deficits in both the velocity and phase distributions are much larger than those for the short one. The synthetic jet is then mounted in the upstream cylinder of a tandem cylinder arrangement to be used as a control actuator for controlling the vibrations of the downstream cylinder. A simple feedback control mechanism is used at a Reynolds number of about 6.3x104. This Reynolds number corresponds to the case' where the downstream cylinder’s response is dominated with two frequency components, one at the resonance frequency of the cylinder, which is excited by broadband turbulence in the flow, and the other at the vortex shedding frequency. Both slits studied for the characterization experiments are used to compare their performance as control actuators. Both jets produce comparable reductions in the vibration of the downstream cylinder. A reduction of about 20% in the total RMS amplitude of the vibrations signal is achieved. This amounts to a reduction of about 50% in the resonant peak and an average value of about 40% in the vortex shedding peak. The optimal values of gain and time lag of the controller are then used to investigate the effect of the jet on the flow. It is found that the short slit jet produced an effect that was traced up to 1.875 diameters downstream, while the effect of the long slit jet dropped dramatically very close to the upstream cylinder. / Thesis / Master of Applied Science (MASc)
383

GenoCAD: linguistic approaches to synthetic biology

Cai, Yizhi 07 May 2010 (has links)
Synthetic biology is an emerging interdisciplinary research field, which leverages the maturation of DNA synthesis technologies. By introducing engineering principles to synthetic biological systems design, synthetic biology shows great potential to shed new lights on biology and benefit human beings. Computer assisted design (CAD) tools will play an important role in the rational design of synthetic genetic systems. This dissertation presents the first CAD tool for synthetic biology — GenoCAD, a linguistic-based web application. By viewing DNA sequences as a language, we developed the first syntactic model to design and verify synthetic genetic constructs. Then we conducted a careful curation of the terminal set in the grammar - the first comprehensive analysis of the Registry of standard biological parts. The implementation and major features of GenoCAD are discussed, and in particular we showed how to develop a domain-specific grammar for BioBrick-based construct design and make GenoCAD a useful tool for the iGEM students. Finally, we went beyond the syntactic level to explore the semantics of synthetic DNA sequences: by associating attributes with biological parts and coupling semantic actions with grammar rules, we developed the first semantic models to relate the genotype to the phenotype of synthetic genetic constructs. The theories and techniques presented in this dissertation, along with the informative results presented, will serve as a foundation for the future developments of GenoCAD. / Ph. D.
384

Nature-inspired systems exploiting porous media for multiphase flows

Umashankar, Viverjita 06 May 2020 (has links)
This thesis studies multi-phase flows within two different types of porous nature-inspired material systems: multi-layered feathers and synthetic trees. (1) How multilayered feathers enhance underwater superhydrophobicity. Inspired by ducks, here we demonstrate that air pockets can withstand up to five times more hydrostatic pressure when using stacked layers of synthetic feathers instead of a single layer. The mechanism for the multi-layered enhancement is the more tortuous pathway required for water impalement, which serves to pressurize the air pockets enclosed in the pores. We study this air compression effect using a probabilistic model, in which we quantify the tortuous pathway in stacked feather layers in terms of filled volume fraction of the pores. Our findings suggest that multi-layered coatings could enable robust underwater superhydrophobicity. (2) Oil-Water separation using synthetic trees. In the world's tallest trees, water evaporating from leaves generates enough suction to lift water over 100 m high. Transpiration can similarly be attained in synthetic trees by coupling nanoporous leaves" with conduits mimicking xylem capillaries. Here, we demonstrate that by adding filters to the free ends of the xylem conduits, the hydraulic load generated by transpiration can be used for oil-water separation. The working principle is illustrated using the pressure balance equation for the synthetic tree. / Master of Science / Nature abounds in complex systems and fascinating phenomena that have inspired us, from the way we live to the things we create. The engineering profession is no exception to being inspired by nature. In fact, engineers have created revolutinary robots inspired by animals. The work in this theis draws inspiration from the water-repellant property (superhydrophobicity) of duck feathers and the transpiration process in plants. In the first study, we created 'synthetic feathers' to study how layers of duck feathers are able to sustain superhydrophobicity under water. We discovered the 'layer-effect' that explains enhanced underwater superhydrophobicity. Surfaces covered in such multi-layered feather-like porous structures are potentially useful for reducing drag in underwater applications. In the second study, we develop a 'synthetic tree' that captures the main attributes of the transpiration mechanism in plants. We show that the 'pull' generated by transpiration can be used for oil-water separation. This macroscopic synthetic tree can be useful in cleaning oil spills.
385

Surface Displayed SNAP as a New Reporter  in Synthetic Biology

Scott, Felicia Yi Xia 10 July 2015 (has links)
The field of synthetic biology has leveraged engineering tools such as molecular cloning to create new biological components, networks, and processes. While many of these components and networks have been deployed in the cytosol, there is a shortage of systems that utilize the surface of the cell. In order to address this shortcoming, we have created a synthetic, surface-displayed substrate anchor for bacteria. This approach allows us to engineer surface-based synthetic biological systems as a complement to existing intracellular approaches. We leveraged the tools of synthetic biology to display a catalytically active enzyme that covalently bonds itself to benzylguanine (BG) groups. We created a fusion protein allowing us to place human O6-alkylguanine DNA alkyltransferase (hAGT), also known as SNAP, on the surface of a bacterial cell. Initially, we used this synthetic component as a tool for spatially segregating orthogonal synthetic gene outputs by visualizing an extracellular synthetic green fluorescent reporter, SNAP-Cell® 505-Star, simultaneously with an intracellular red fluorescent protein, mCherry. Moreover, we have shown that our construct enables cells to selectively bond to BG-conjugated magnetic beads. As a result, we have demonstrated that surface displayed SNAP facilitates engineering a direct channel between intracellular gene expression and extracellular material capture. In the near future, we believe this magnetic capture can be expanded as a sortable reporter for synthetic biology as a direct extension of this work. Moreover, our work serves as an enabling technology, paving the way for extracellular synthetic biological systems that may coexist orthogonally to intracellular processes. / Master of Science
386

Digital Architecture for a Computer Based Imaging System

McIntosh, John Osborn 01 January 1979 (has links) (PDF)
There is a great need for a graphic simulation system used as a training device to take the place of actual flying. A good system will greatly reduce the cost of training men as well as cut down on casualties. Several systems have been tried and are now in use. Among them are two that are worthy of more study. These are the CCTV or model board and the digital systems. Both have several disadvantages that create a need for a new system. One such system is an optically based digitally processes system that combines the best features of two previous systems. This system uses charge-coupled-device memories that are digitally accessed by a microcomputer based system. The information from the CCD's is then processed and calculations are performed on it to transform it into a form that can be displayed on a cockpit-like screen. The system also allows for interaction between the pilot and itself.
387

Friction, wear and lubrication of a poly(2-hydroxyethyl methacrylate) hydrogel

Freeman, Mark E. 18 September 2008 (has links)
Poly(2-hydroxyethyl) methacrylate, (polyHEMA), hydrogels are synthesized for tribological study to investigate their potential for use as synthetic articular cartilage. A four factor, two level designed experiment was performed to evaluate friction and wear of polyHEMA. Tests were carried out using a friction and wear test device developed for biotribology research. The geometry consisted of a ball on flat; 6mm stainless steel ball and flat polyHEMA discs. Test factors were load, lubrication, hydration and material crosslink density. Linear oscillating sliding contact tests were performed on each polyHEMA disc for approximately 30 minutes per test. Friction coefficients found ranged from 0.05 to 1.7. Linear wear measured ranged from 0.02 mm to 1.32 mm. / Master of Science
388

Protein Bioseparation using Synthetic Membranes: Enhancement of Selectivity and Throughput

Kanani, Dharmeshkumar M. January 2007 (has links)
Cost-effective large-scale protein bioseparation will be the key issue for the biopharmaceutical industry in the coming years. Conventional protein purification techniques are severely limited in the sense that they give either good selectivity of separation at the cost of throughput or vice versa. Synthetic membrane based bioseparation techniques such as high-resolution ultrafiltration and membrane chromatography have the potential to combine high-throughput with high selectivity. This thesis focuses on approaches for obtaining both selectivity and throughput in membrane based protein bioseparation processes. Obtaining high selectivity is one of the main objectives in high-resolution ultrafiltration. This thesis reports a novel approach for flexibly manipulating the selectivity of protein separation using a dual-facilitating agent. In this study it has been shown for the first time that the selectivity of separation can be altered as desired, i.e. if required, the selectivity can be reversed and thereby smaller proteins can be retained and larger proteins can be made to permeate by using a dual-facilitating agent. The results are explained in terms of protein-protein electrostatic interactions and Donnan effect. This novel approach is expected to significantly increase the flexibility of carrying out high-resolution ultrafiltration. Membrane chromatography is based on the use of stacks of microporous synthetic membranes as chromatographic media. Due to lower binding capacities of commercial membranes in comparison to conventional beads for packed bed chromatography, the commercial success of membrane chromatography is largely limited to the flow-through applications. The study on membrane chromatography addresses the performances of new types of high-capacity macroporous gel-filled membranes for ion-exchange chromatography of proteins. This work demonstrates the suitability of using one of these novel membranes for fractionation of plasma proteins. Membrane fouling reduces product throughput and is considered a major problem in pressure driven membrane processes such as microfiltration and ultrafiltration. This thesis reports some significant contributions in the area of membrane fouling. A novel yet conceptually simple approach for modeling flux decline in constant pressure ultrafiltration, which takes into account the interplay between flux, concentration polarization and membrane fouling is discussed. Conventional fouling models account for the effects of concentration polarization and membrane fouling in a simple additive way. The basic hypothesis in the model discussed here is that flux decline in constant pressure ultrafiltration is self-attenuating in nature. This new approach is expected to be very useful in deciding the start-up conditions in membrane processes. Despite widespread use of in-line microfiltration for sterilization of therapeutic proteins prior to formulation, there has been no systematic study on fouling in such processes. Part of the fouling work in this thesis examines how resistance to filtration increases during in-line microfiltration of concentrated protein solution and the mechanism of protein fouling. It assesses the severity of fouling in terms of apparent reversible fouling and irreversible fouling. Traditional methods to measure the protein fouling resistances of membranes are time consuming and expensive. This thesis reports three protocols to compare the performance of microfiltration membranes for protein filtration. The first protocol, which is based on accelerated fouling in the dead end mode using pulsed injection technique is rapid, simple, and cost effective and gives valuable information about membrane performance. The remaining two protocols are based on the critical flux concept. / Thesis / Doctor of Philosophy (PhD)
389

Fundamental properties of Synthetic O-D Generation Formulations and Solutions

Paramahamsan, Harinarayan 17 February 1999 (has links)
Origin-Destination (O-D) matrices are required in order to model traffic routing behavior in networks. Direct techniques for collecting O-D information from home and roadside interviews have historically been utilized to estimate O-D tables. However, these techniques are not only very costly, labor intensive, and disruptive to trip makers, but traditionally also do not capture traffic peaking behavior, which is often required for traffic operational purposes. Consequently, more cost-effective indirect or synthetic O-D estimation techniques have been developed, and continue to be developed. They utilize readily available traffic volume counts to estimate the most likely O-D tables that may have generated the observed link counts. This thesis describes the basic formulations that have been proposed to formulate and solve the static O-D problem synthetically using link flow observations based on Maximum Entropy techniques. As is the case with many mathematical solutions to engineering problems, a number of simplifying assumptions have been made in order to solve the synthetic O-D problem. Unfortunately, the descriptions of these simplifying assumptions are often not fully described in the literature, and in some cases, these assumptions are not mentioned at all. Furthermore, the literature fails to systematically demonstrate what impact these assumptions have on the final O-D table estimate. Therefore, this thesis utilizes simple hypothetical networks to; 1. Demonstrate and compare the two main types of synthetic O-D formulations, namely the trip and volume based formulations. 2. Track the O-D estimation procedure from its initial formulation to its final formulation, demonstrating all significant assumptions that have been made and the implications of these assumptions on the final solution. 3. Demonstrate to what extent the final O-D estimation formulation remains valid when these assumptions are invoked. 4. Test the applicability of some packages which implement the various formulations and solution techniques that are available. / Master of Science
390

Alternatives to [4+1] carbocyclic annulations

Dossett, David Lawrence January 1986 (has links)
6-Carboethoxybicyclo [3.3.0] oct-6-en-2-one has been prepared by the intramolecular [4+1] cyclopentene annulation method. This compound and its precursor, 6-vinyl-6-carboethoxybicyclo[3.1.0]hexan-2-one were attained as the necessary standards for the investigation of the course of intramolecular Michael addition-alkylation sequence of l-phenylsulfonyl-6-carboethoxyocta-5,7-dien-2-one. / M.S.

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