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1
Johansson, Lars. "SURFACE DRAG MODELING FOR MILLED SURFACES." Thesis, KTH, Mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204017.
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One of the governing sources of energy loss in a modern day jet engine is attributed to surfacedrag. This energy loss can be divided into friction loss and to surface geometry loss. Thefriction loss is the shear stress the fluid experience due to a no slip condition at the wall, whilethe surface geometry loss is due to pressure drop when the fuel passes an obstacle.The objective of this work is to study the drag coefficient of a plate for different types ofmilled tracks and for different kinds of flow conditions. The theories used to calculate thedrag coefficient are based on the momentum thickness theory including shear stress- andpressure integration. The computations were carried out with ANSYS CFX assuming a ShearStress Transport 𝑘 − 𝜔 turbulence model. The steady state flow conditions tested are varyingboundary layer thicknesses, milled track heights, milled track widths, Reynolds numbers overthe milled track height, Reynolds numbers over the plate length and free-stream angle ofattack. By knowing what affects the drag coefficient for different types of milled tracks, morepractical models can be developed making the prediction of surface drag inside the jet enginemore accurate.This report has resulted in a formula that predicts the drag coefficient for different types ofmilled surfaces. The formula is derived from the assumption that the CFD results on ANSYSCFX are correct. A physical test has not been made to verify those results, however this has tobe done to prove that this formula is valid.
2
Andrews, Marilyn Mockus 1958. "Characterization of the surface acidity of passivated iron particles by flow microcalorimetry." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276614.
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The characteristics of passivated iron particles have been examined with flow microcalorimetry to determine the acidic nature of the surface sites. The molar heat of adsorption of pyridine from hexane was measured with a FMC and a differential refractive index detector, at 23 and 40°C. The adsorption data were found to obey the assumptions of the Freundlich isotherm. The adsorption densities at different temperatures were used to calculate the isosteric heat of adsorption. The molar heat of adsorption of triethylamine from hexane was also measured and combined with the data for pyridine in order to calculate the Drago constants for the iron particles. A static adsorption method was used for the adsorption of pyridine from hexane onto the iron particles, for comparison with the dynamic method. The heat of wetting for the iron particles, with hexane, has also been measured. The iron particles were examined with X-ray diffraction. Mossbauer spectroscopy, XPS, SEM, TEM, and electrophoresis to characterize the surface layer. These techniques have revealed that the iron particles are coated with ferric oxide and this surface is amphoteric in aqueous solutions.
3
Yazicioglu, Refet Firat. "Surface Micromachined Capacitive Accelerometers Using Mems Technology." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1093475/index.pdf.
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Micromachined accelerometers have found large attention in recent years due
to their low-cost and small size. There are extensive studies with different
approaches to implement accelerometers with increased performance for a number of
military and industrial applications, such as guidance control of missiles, active
suspension control in automobiles, and various consumer electronics devices. This
thesis reports the development of various capacitive micromachined accelerometers
and various integrated CMOS readout circuits that can be hybrid-connected to
accelerometers to implement low-cost accelerometer systems.
Various micromachined accelerometer prototypes are designed and optimized
with the finite element (FEM) simulation program, COVENTORWARE, considering
a simple 3-mask surface micromachining process, where electroplated nickel is used
as the structural layer. There are 8 different accelerometer prototypes with a total of
65 different structures that are fabricated and tested. These accelerometer structures occupy areas ranging from 0.2 mm2 to 0.9 mm2 and provide sensitivities in the range
of 1-69 fF/g.
Various capacitive readout circuits for micromachined accelerometers are
designed and fabricated using the AMS 0.8 µm n-well CMOS process, including a single-ended and a fully-differential switched-capacitor readout circuits that can operate in both open-loop and close-loop. Using the same process, a buffer circuit with 2.26fF input capacitance is also implemented to be used with micromachined gyroscopes. A single-ended readout circuit is hybrid connected to a fabricated accelerometer to implement an open-loop accelerometer system, which occupies an area less than 1 cm2 and weighs less than 5 gr. The system operation is verified with various tests, which show that the system has a voltage sensitivity of 15.7 mV/g, a nonlinearity of 0.29 %, a noise floor of 487 Hz µ
g , and a bias instability of 13.9 mg, while dissipating less than 20 mW power from a 5 V supply. The system presented in this research is the first accelerometer system developed in Turkey, and this research is a part of the study to implement a national inertial measurement unit composed of low-cost micromachined accelerometers and gyroscopes.
4
Hossain, Mohammad Mokbul. "Plasma technology for deposition and surface modification." Berlin Logos, 2008. http://d-nb.info/993574106/04.
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Gunnarsson, Sarius Niklas. "Surface Technology for Optical and Electrical Connectors." Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63626.
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This thesis treats surface engineering with the purpose of improved quality of optical and electricalconnectors with a focus on electroplated and magnetron sputtered materials. In electroforming of tools formanufacturing optical connectors, the influence of ultrasonic agitation on intrinsic stresses and fillingproperties of electroplated Ni has been studied. It is established that the ultrasonic agitation at the substratesurface during deposition impacts the intrinsic stresses making it possible to increase deposition rate viacurrent density, with stress-free or low-stress levels in the Ni layers. Reduced variations of the intrinsicstress over the surface with the current density is a further important result. Filling of grooves byelectroplating of Ni using ultrasonic agitation is demonstrated. This is due to increasing mass transport ofspecies into the grooves compared to conventional pumped agitation. The enhanced filling propertiesmakes it possible to electroplate Ni in the bottom of high-aspect-ratio grooves. In order to industriallyimplement new nanocomposite coatings on electronic connectors, studies have been performed regardingthe thermal diffusion barrier properties against Cu for Ti-Si-C and Ti-Si-C-Ag nanocomposites, depositeddirectly onto Cu substrates or with sputtered Ni, Ti or electroplated Ni as an intermediate coating. Theapplication of an electroplated Ni diffusion barrier coating, hinders Cu from reaching the surface of thenanocomposites. Also, Ti-Si-C-Ag nanocomposite deposited on magnetron sputtered Ni or Ti on Cusubstrates hinder Cu from diffusing to the surface after annealing. The contact resistance of Ag-Pdtopcoated Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings in contact with hard gold is shown tocompete with hard gold in contact with itself, as electrical contact coatings at contact forces around 5 N.Ag-Pd topcoated Ti-Si-C-Ag-Pd in contact with hard gold is shown to have approximately the same contactresistance as hard gold in contact with hard gold at contact forces around 0.1 N, which here is in the 10 mΩrange, while Ti-Si-C-Ag nanocomposite coatings in contact with hard gold has a contact resistance that isup to 10 times higher. The overall contribution of this thesis can be summarised as a deeper knowledge andunderstanding of techniques and coatings, that help reduce cost and increase reliability of electronics.
6
Doherty, Kyle George. "Microplasma technology for influencing cell-surface interactions." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/18213/.
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Cataracts are the most common cause of preventable blindness worldwide. During cataract surgery a polymeric intraocular lens (IOL) is used to replace the cloudy natural lens. The most common post-operative complication is posterior capsule opacification (PCO). PCO is a wound healing response related to scarring, in which cellular changes disrupt the light path to the back of the eye through various processes, requiring a costly surgery to restore vision. The material of the IOL has been shown to affect PCO and it is hypothesised that the surface modification of IOL materials may be able to reduce the incidence of PCO. The use of plasmas established in the field of biomaterials modification and atmospheric pressure processes have significant benefits over the previous low pressure systems. In this work investigates the use of an atmospheric pressure plasma jet to modify the surface properties of polymeric materials, with the aim of developing a surface treatment method for use on IOLs. Materials and Methods The centre of polystyrene (PS) and poly(methyl methacrylate)(PMMA) surfaces were treated with an atmospheric pressure microplasma jet. The modification of surfaces was characterised by spatially resolved water contact angle, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). LECs were seeded onto surfaces and grown for 1-7 days. Cell attachment, growth and morphology were examined microscopically. The concentrations of some cytokines implicated in PCO (transforming growth factor-β2, basic fibroblast growth factor, interleukin-1, interleukin-6, and tumour necrosis factor-α) in culture medium were examined at specific time points. Tissue culture polystyrene and untreated materials served as controls. Atmospheric pressure plasma polymerisation of amine containing monomers using a plasma jet was also investigated. Results and Discussions The size of surface treatment could be tailored by altering flow rate and sample-nozzle distance. Surface treatment was due to an increase in surface oxygen content and plasma treatment did not cause a significant change in surface roughness. Plasma treatment increased the LEC adhesion to substrates. LECs were densely populated in the centre of treated materials and cells lacked the cobblestone morphology typical of epithelial cells. The secretion of inflammatory cytokines by LECs grown on plasma treated surfaces did not appear to be up-regulated in comparison to tissue culture polystyrene, however these results are preliminary. This work demonstrated that atmospheric pressure plasma polymerisation can be achieved using the plasma jet system to incorporate nitrogen functionalisation onto PS surfaces; however oxygen was also incorporated onto surfaces. Conclusions This work demonstrates that an atmospheric pressure microplasma jet can be used to modify surfaces in a spatially defined manner, without damaging the polymer surfaces. The increase in surface oxygen promotes cell adhesion which can be confined to an area <3mm. This treatment size is too large to be used to create different spatially defined treatments on IOL optics as the typical optic diameter is only 6mm. The large treatment size is possibly due to gas convection spreading reactive species across the surface of samples when the plasma jet reaches the surface. Plasma polymerisation could possibly be used to incorporate functional groups which promote LEC growth which maintains an epithelial morphology.
7
Hui, Ip Kee. "Analysis of surface mount technology solder joints." Thesis, Brunel University, 1996. http://bura.brunel.ac.uk/handle/2438/5380.
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The factors determining the quality of surface mount technology (SMT) solder joints are numerous, and complex. The exploration of these factors, and how they may affect the reliability and quality of the joints can only be achieved through continuous research. In this project, essential areas of SMT joints were selected for study and analysis, with the intention of providing additional design and process guidelines for the production of quality SMT joints. In the infrared reflow process, one of the common defect phenomena is the occurrence of tombstoning; that is after soldering only one end of the component is soldered while the other is lifted up, assuming a position like a tombstone. The initiation of tombstoning during reflow was analysed based on the forces acting on the component. A model was developed to predict the initiation of this phenomenon. The model shows that, under vibration-free conditions, the surface tension of the molten solder is the source of the force causing the initiation of tombstoning. The contact angle, which varies with the length of the printed circuit board solder land, has a significant effect on the value of the surface tension acting as a force pulling upward on the component. The model further shows that tombstoning initiation is due to the combined effects of the surface tension; the weight of the component; the dimensions of the component; the length of the solder underneath the component; and the length of the solder protruding from the end of the component. Selected components were used as examples for predicting the conditions of initiation, and these conditions were further substantiated by a series of experiments. Another area of study was a method which directly pulled the components off printed circuit boards and this was used as a means for testing the bond quality of surface mount technology leadless chip solder joints. Components D7243, CC1206, RC1206, RC121O, and CC1 812 were selected for this study. It was found that the ultimate tensile force which breaks a component off the printed circuit board has the potential to be used as a parameter for measuring the quality of the solder joint. The effect of solder thickness on the strength of a joint has also been investigated. The shape of joints soldered by two methods, wave soldering and infrared reflow, were compared. Joints at the two ends of a component produced by infrared reflow were found more uniform than the ones produced by wave soldering. A recommendation is made here for the wave soldering approach in achieving uniform solder joints. The effects of solder shape on the joint strength were further investigated by finite element analysis. A convex joint was found marginally more robust than a concave joint. Two aspects of the internal structure of SMT solder joints were investigated, void content and copper/tin intermetallic compounds. The voiding conditions of wave-soldered and infrared reflow joints were compared. No voids were found in all specimens that were produced by wave soldering. However, there were always voids inside joints produced by infrared reflow. Microhardness tests indicated that the hardness of compounds at the copper/solder interface of infrared reflowed joints is lower than that in the wave-soldered joints. It is considered that the lower hardness of the interfacial region of the infrared reflowed joints is due to the presence of voids. Scanning electron microscopy was used to study the formation of copper/tin intermetallic compounds for joints produced by infrared reflow. The results show that Cu 6 Sn5 was the only compound with a detectable thickness. Other compounds such as Cu3 Sn, were virtually not found at all. Aging of the joints at 100°C, shows that both the Cu 6Sn5 and the overall interfacial thickness grew with time. One of the important areas which had been overlooked previously and was studied in some details was the effects of solder paste exposure on the quality of solder paste. The characteristic changes of solder paste due to exposure were investigated in three areas, weight loss, tackiness, and rheology. The evaporation of low boiling point solvents was considered as the main contribution to the loss in the weight of the solder paste. The weight loss against exposure time was found to follow an exponential behaviour. A method was designed to evaluate the tackiness changes of solder paste due to exposure. It was found that the decay of tackiness against exposure time can be expressed by a power law. It is recommended that solder paste manufacturers should provide the necessary characteristic constants so as to enable the characteristics to be calculated after a specific exposure. The rheological changes of the solder paste as a result of exposure were also investigated. The implication on the printability of the solder paste due to these changes was studied and discussed.
8
Golding, Randy Dale. "Synthesis and application of alkyl dihydrochlorosilanes: A new approach to the surface modification of porous silica." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184427.
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Three alkyldihydrochlorosilanes were synthesized; ethyldihydrochlorosilane, octyldihydrochlorosilane and octadecyldihydrosilane. Ethyldihydrochlorosilane was produced by the reaction of ethylsilane with mercuric chloride and the other two chlorosilanes were produced by the reaction of the alkyl Grignard reagent with dichlorosilane. Each alkyldihydrochlorosilane was reacted with porous silica in an attempt to discover the extent of reaction or the highest surface concentration of bonded groups attainable. The reaction between these alkydihydrochlorosilanes and porous silica was compared to the reaction between silica and the analogous alkyldimethylchlorosilane. The rate of reaction of both type of chlorosilane was found to be essentially the same. The maximum surface concentration of bonded surface groups attainable by alkyldihydrochlorosilanes was found to be approximately 1.3 #moles/m² greater than that attainable by alkyldimethylchlorosilanes. This increased surface coverage seemed to depend very little on the chain length of the alkyl group and was attributed to the decrease in steric hindrance of the bonding silicon atom of the silane. Surface bound silyl hydrides could be oxidized selectively and sequentially to form silane silanols. Surface silanes also appeared to reduce chloroplatinic acid, but were not observed to add efficiently to olefins. The chromatographic properties of silica modified with alkyldihydrochlorosilanes were compared to those of equivalent silicas modified with alkyldimethylchlorosilanes and alkyltrichlorosilanes before and after the surface silanes were oxidized. Both normal and reversed-phase liquid chromatographic studies were conducted. In general, it was found that alkyldihydrochlorosilanes yielded the most polar modified silicas. This greater surface polarity was attributed to an increase in the activity of water in the near surface region of the bonded phase.
9
Lee, Chee-kwan. "Modelling of flexible surfaces using a point mass system /." [Hong Kong : University of Hong Kong], 1992. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13204889.
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Burton, Zachary Travis. "Surface characterization, adhesion, and friction properties of hydrophobic leaf surfaces and nanopatterned polymers for superhydrophobic surfaces." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1160489659.
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Lawson, Glenn E. "The effects of evaporation rate, solvent, and substrate on the surface segregation of block copolymers." Thesis, This resource online, 1985. http://scholar.lib.vt.edu/theses/available/etd-03042009-041008/.
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Nordström, Helena. "Fragment Based Drug Discovery with Surface Plasmon Resonance Technology." Doctoral thesis, Uppsala universitet, Biokemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209136.
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Fragment based drug discovery (FBDD) has been applied to two protease drug targets, MMP-12 and HIV-1 protease. The primary screening and characterization of hit fragments were performed with surface plasmon resonance -technology. Further evaluation of the interaction was done by inhibition studies and in one case with X-ray crystallography. The focus of the two projects was different. Many MMP inhibitors contain a strong zinc chelating group, hydroxamate, interacting with the catalytic zinc atom. This strategy may be the cause for the low specificity of MMP inhibitors. Using FBDD we found a fragment with an unusual strong affinity for MMP-12. An inhibition assay confirmed that it was an inhibitor but indicated a stoichiometry of 2:1. Crystallography data revealed that an adduct of the fragment was bound in the active site, with interactions both with the catalytic zinc and the S1’ pocket. This may present a new scaffold for MMP-12 inhibitors. For HIV-1 protease the focus was on identifying inhibitors not sensitive to current resistance mutations. A fragment library for screening with SPR-technology was designed and used for screening against wild type enzyme and three variants with resistance mutations. Many of the hits were promiscuous but a number of fragments with possible allosteric inhibition mechanism were identified. The temperature dependency of the dissociation rate and reported resistance mutations was studied with thermodynamics. A good, but not perfect correlation was found between resistance and both the dissociation data and the free energy for dissociation compared to data from wild type enzyme. However, the type of mutation also influenced the results. The flap mutation G48V displayed thermodynamic profiles not completely correlating with resistance. It was found that dissociation rate and thermodynamics may complement each other when studying resistance, but only one of them may not be enough.
13
Howe, Daniel S. "Electronics and Communication Technology for a Surface Stimulation Device." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1222456488.
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Lau, Chi Hian. "Chemical, electronic and electrochemical properties of diamond thin films." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:53a0886c-14ad-431a-975d-0ecca8fc8968.
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Diamond is of interest as an advanced functional material, since the extreme physical properties of diamond, suggests it is ideally suited to a range of new demanding applications. In this context, the thesis explores basic surface chemical properties of diamond thin films, along with electrochemical, electronic and electron emission processes involving this material. New experiments are reported concerning the nature of surface conductivity on diamond. Measurements clearly show that the conductivity only arises if a hydrogenated diamond surface is exposed to water vapour, in the presence of chemical species capable of acting as electron acceptors. The conduction properties of surface conductive diamond in aqueous solution are also studied, and the first detailed electrochemical investigations of this material are described. Comparative electrochemical studies of nanocrystalline and boron-doped diamond have been performed. Investigations of electrode stability, and the accessible "potential window" are described, as well as the behaviour of a range of 'redox' systems, including transition metal complexes, metal deposition/stripping, and bio-related organic species. Significant differences between the behaviour of nanodiamond and microcrystalline boron-doped material are observed. A range of surface chemical and threshold photoemission studies of diamond thin films are reported. The results indicate that quantum photoyields (QPYs) are insensitive to the diamond "quality", although the wavelength selectivity is dependent on it. The adsorption of oxygen strongly reduces the QPY, although this only occurs slowly in the presence of O2 because of a low reactive sticking probability. Much more rapid uptake of oxygen and consequent reduction of photoyield is observed in the presence of atomic O or electronically excited dioxygen O2*. The presence of alkali metals on the diamond surface increases the QPY, and reduces the sensitivity of the QPY to surface oxygen. Significant differences between the surface chemical properties of Li, and other adsorbed akali metals (K and Cs) are observed.
15
Li, Tukun. "Softgauges for surface texture." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/11357/.
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Surface texture plays an important role in the specification of a precision workpiece. However, the route of traceability for surface texture measurements is not well developed. One of the main technical obstacles is the lack of tools to check traceability of the software of surface measuring instruments and to estimate uncertainty contributed by the software. To this end, the concept of softgauges (i.e. software measurement standards) for surface texture has been introduced into the international standards. The presented thesis documents the realisation of softgauges for surface texture, which is a part of the National Measurement System in the UK. These standards, in the form of the reference dataset with reference results, have been developed by both simulation and experimental methods. The analysis of software uncertainty has been undertaken. These measurement standards have been used to verify both reference software(developed by the National Measurement Institutes) and commercial packages (developed by instrument manufacturers). In addition, the evaluation of the measurement uncertainty in workshop level has been carried on. These developed standards provided a novel route to demonstrate metrological traceability of most surface profile parameters. Currently, these standards are distributed via the internet by the National Measurement Laboratory (NPL) in the UK. These standards are also recognised by NIST in the USA and PTB in Germany, and these organisations would also provide a suitable vehicle to distribute of the results of this study.
16
Tang, Zuojian 1967. "Surface morphology of polyethylene blown films." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31072.
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The properties of blown polyethylene (PE) films depend on various factors, including crystallinity, morphology, and orientation, in addition to chemical composition. It has been shown that the optical properties are strongly influenced by surface morphology. In this project, we use non-contact atomic force microscopy (AFM) and polarized light microscopy (PLM) to visualize surface and bulk morphology. Various techniques, such as surface and line roughness, surface and line fractal dimension, pair-correlation function and nearest neighbor distance distribution function, are employed to quantify the description of morphology and to compare the morphological characteristics of a number of polyolefin films of commercial interest. A comprehensive quantitative analysis of surface topography has been performed. The co-monomer of the PE resins was found to play a significant role in the formation and the orientation of spherulite-like domains. The film cross-section microstructure has been evaluated qualitatively by using both AFM and PLM. However, quantitative analysis of bulk morphology cannot be obtained due to knife effects.
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Matthews, Thomas R. "Surface properties of poly(ethylene terephthalate) /." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1177515548.
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Thesis (M.S.Ch.E.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for The Masters of Science Degree in Chemical Engineering." Bibliography: leaves 76-77.
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Frantzen, Michelle E. Gunn. "Abatement of perfluorocompounds and chlorofluorocarbons using surface wave plasma technology." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4734.
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Application of surface wave plasma technology for effective abatement of
environmentally harmful gases such as perfluorocompounds and chlorofluorocarbons is
investigated. Perfluorocompounds (PFCs) are gases that contribute to forced global
warming and have been favored for wafer etch and chamber clean applications in the
semiconductor industry. Chlorofluorocarbons (CFCs) are ozone depleting gases that
were used as refrigerants for commercial and domestic condensers and air conditioners,
but current reserves still pose threats to environmental sustainability. Increased average
global temperatures and further destruction of the ozone layer have prompted proposal
of international initiatives such as the Montreal Protocols and the Kyoto Agreement to
curtail emissions of such fugitive gases into the environment. These have increased the
need for effective abatement technologies to control such emissions and include surface
wave plasma abatement, the subject of this dissertation. Surface wave plasmas are
considered high frequency non-equilibrium traveling wave discharges in contrast to the
more frequently used standing wave discharges. The use of surface wave plasmas have
the advantages of a variety of discharge vessel shapes, reproducibility of application, numerous operating conditions and large plasma volumes which ultimately produce low,
molecular weight byproducts that are associated with high effective electron
temperatures but low heavy particle temperatures. For these reasons, surface wave
plasma abatement technology was developed for the destruction and removal of PFCs
and CFCs.
Results include final destruction and removal efficiencies (DREs) for
octafluorocyclobutane greater than 99.8%, dichlorodifluoromethane greater than
99.995% and trichlorofluoromethane greater than 99.999% using moderate applied
microwave powers of less than 2000 watts with the production of low molecular weight
byproducts, such as CO2, CO, HF and HCl, that prevent environmentally harmful
process emissions from entering the atmosphere. Characterizations of the initial and
final products were accomplished by the use of Fourier transform infrared spectroscopy
and quadrupole mass spectrometry to provide independent quantitative analyses of
plasma processes. In addition to these analytical methods, Global_Kin a kinetic model,
of plasma reactions were conducted and compared to all the experimental data
determined in order to facilitate understanding of the chemistry involved in the surface
wave plasma abatement applications studied. Basic plasma reaction mechanisms were
determined for the abatement of octafluorocyclobutane and dichlorodifluoromethane.
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Hau, Lap Wing. "Electrokinetically-driven liquid flows in microchannels using surface-chemistry technology /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20HAU.
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Lovelace, Edward C. "Smoother sailing ahead : integrating information technology into the surface Navy." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA285973.
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Thesis (M.S. in Information Technology Management) Naval Postgraduate School, September 1994.Thesis advisor(s): Patrick J. Parker, David R. Henderson. "September 1994." Bibliography: p. 63-66. Also available online.
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Kim, Taek. "Developments in gallium nitride vertical cavity surface emitting laser technology." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366793.
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Yu, Xinren. "Pavement Surface Distress Detection and Evaluation Using Image Processing Technology." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302032254.
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Jonsson, Patrik. "Surface Status Classification, Utilizing Image Sensor Technology and Computer Models." Doctoral thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-24828.
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There is a great need to develop systems that can continuously provide correct information about road surface status depending on the prevailing weather conditions. This will minimize accidents and optimize transportation. In this thesis different methods for the determination of the road surface status have been studied and analyzed, and suggestions of new technology are proposed. Information about the road surface status is obtained traditionally from various sensors mounted directly in the road surface. This information must then be analyzed to create automated warning systems for road users and road maintenance personnel. The purpose of this thesis is to investigate how existing technologies can be used to obtain a more accurate description of the current road conditions. Another purpose is also to investigate how existing technologies can be used to obtain a more accurate description of the current road conditions. Furthermore, the aim is to develop non-contact technologies able to determine and classify road conditions over a larger area, since there is no system available today that can identify differences in road surface status in the wheel tracks and between the wheel tracks. Literature studies have been carried out to find the latest state of the art research and technology, and the research work is mainly based on empirical studies. A large part of the research has involved planning and setting up laboratory experiments to test and verify hypotheses that have emerged from the literature studies. Initially a few traditional road-mounted sensors were analyzed regarding their ability to determine the road conditions and the impact on their measured values when the sensors were exposed to contamination agents such as glycol and oil. Furthermore, non-contact methods for determining the status of the road surface have been studied. Images from cameras working in the visible range, together data from the Swedish Transportation Administration road weather stations, have been used to develop computerized road status classification models that can distinguish between a dry, wet, icy and snowy surface. Field observations have also been performed to get the ground truth for developing these models. In order to improve the ability to accurately distinguish between different surface statuses, measurement systems involving sensors working in the Near-Infrared (NIR) range have been utilized. In this thesis a new imaging method for determining road conditions with NIR camera technology is developed and described. This method was tested in a field study performed during the winter 2013-2014 with successful results. The results show that some traditional sensors could be used even with future user-friendly de-icing chemicals. The findings from using visual camera systems and meteorological parameters to determine the road status showed that they provide previously unknown information about road conditions. It was discovered that certain road conditions such as black ice is not always detectable using this technology. Therefore, research was performed that utilized the NIR region where it proved to be possible to detect and distinguish different road conditions, such as black ice. NIR camera technology was introduced in the research since the aim of the thesis was to find a method that provides information on the status of the road over a larger area. The results show that if several images taken in different spectral bands are analyzed with the support of advanced computer models, it is possible to distinguish between a dry, wet, icy and snowy surface. This resulted in the development of a NIR camera system that can distinguish between different surface statuses. Finally, two of these prototype systems for road condition classification were evaluated. These systems were installed at E14 on both sides of the border between Sweden and Norway. The results of these field tests show that this new road status classification, based on NIR imaging spectral analysis, provides new information about the status of the road surface, compared to what can be obtained from existing measurement systems, particularly for detecting differences in and between the wheel tracks.
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Clough, A. R. "A study on the near-field interactions of ultrasonic surface waves with surface-breaking defects." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58643/.
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This thesis is concerned with the detection of surface-breaking defects, such as stress corrosion cracking, using an ultrasonic scanning approach in which a laser source and detector are scanned over the near-field of a defect. Large increases in the amplitude and frequency content of an incident ultrasonic wave are present when either the source or the detector is very close to the defect, leading to a phenomenon known as ultrasonic near-field enhancement. The extent of the ultrasonic enhancement varies with defect characteristics such as defect depth and angle to the surface. Ultrasonic enhancement is observed in both experiment and finite element simulations using Rayleigh waves for both scanning laser detection and scanning laser source methods. The near-field enhancement is shown to vary as a function of the angle of the defect to the horizontal for Rayleigh wave enhancements, allowing the positioning and characterisation of artificial angled defects that are similar to rolling contact fatigue defects in railtrack. The mechanisms behind the near-field enhancement of Rayleigh waves at angled defects are identified, and this aids in the understanding of the behaviour of ultrasound as it interacts with surface-breaking defects. Ultrasonic enhancements are also reported to be present in individual Lamb wave modes for interactions with artificial open-mouthed defects in thin plates, which are similar to the open end of stress corrosion defects. The mechanisms behind both the scanning laser detection and scanning laser source enhancements are identified and used to explain the variation in the enhancement as a function of increasing defect severity. Positioning of these defects is also achieved by identification of the enhancement location. Finally, the scanning laser technique is applied to real stress-driven defects, and both scanning approaches are shown to be capable of detecting partially-closed defects in a variety of sample geometries. The position, geometric alignment and an estimate of the defect depth are obtained for real defects in thin plates, pipework sections and in irregularly shaped engine components.
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Li, Hongchun. "A study on wear and surface roughness of work roll in cold rolling." School of Mechanical, Materials and Mechatronic Engineering - Faculty of Engineering, 2008. http://ro.uow.edu.au/theses/125.
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The objective of this study is to improve our understanding of the evolution and tribological behaviour of work roll surfaces in cold rolling because surface deterioration affects the quality of products and the efficiency of production. The cost of rolls is almost 25% of the cost of cold steel production. An experimental Lateral Set-testing (LST) mini-mill was developed to make use of the Gleeble 3500 thermo-mechanical simulator functions to evaluate, for the first time, the roll material surface features, surface roughness, fast Fourier transform (FFT) and Power Spectral Density (PSD) of frequency distribution, after single and multi-pass rolling. A low carbon-steel was prepared for the paired disc and then experiments on disc-to-disc wear were carried out to test surface deterioration and friction. In the laboratory, material imitating an industrial roll was manufactured. One batch contained 4%Cr and another contained 4%Cr plus approximately 0.1% Ti. These materials were compared against each other in the LST and disc-to-disc experiments. Experiments considered a series of parameters, including strip reduction, speed, and lubrication, while the disc-to-disc experiments considered duration of wear, forward and backward slip and load amplitude. The surfaces of the LST roller and disc were evaluated by surface technologies such as Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), and surface profile-meters. Transmission Electron Microscope (TEM) and X-ray diffraction wear properties. Test results from the mini-mill reveal that dominant waviness of the surface roughness still exists on the surface after a single pass of rolling and a 30.5% reduction is a critical reduction level that has a significant influence on the density of power spectrum. A rougher work piece results in a larger power spectrum of the surface profile. It has found that the PSD altitude of the roller surface is significantly affected axially but is more sensitive to its original surface roughness circumferentially. It is distributed in an inverse order to the surface roughness in a high frequency domain. The addition of Ti alters surface deterioration. Lubrication has a significant effect on surfaces containing either 4Cr% or 4%Cr+Ti, affecting surface roughness of rollers containing 4%Cr more significantly. In the disc-to-disc tests, more material was removed in the first 60 minutes from the disc containing Ti than the disc containing only 4%Cr. In general, roll material with 4%Cr+Ti reveals to have better anti-abrasive properties than the roll with only 4%Cr, while lubrication significantly reduced the wear rate and amount of material removed from both materials. The speed of the disc influences the weight loss, ie, the higher the speed the greater the amount of material removed. The slip rate also affects roll wear and weight loss because as the speed increases, so do the slip and loss of weight. The coefficients of friction are between 0.35~0.75 when the contact was dry and 0.06~0.11 when lubrication was applied. Adhesive friction dominated the dry contact while a mixed lubrication regime features friction behaviour when emulsion lubrication was applied. A backward slip of 2% and a forward slip of 1.5% resulted in a different coefficient of friction in dry contact mode although the corresponding torques were similar. The torque and coefficient of friction are found to increase with disc speed in dry contact condition. Lubrication alters the friction of both materials. The coefficient of friction decreases with speed on the disc with added Ti but the effect of load is in the opposite trend, while the disc with 4%Cr was less influenced by speed. The coefficient of friction is more sensitive to load at higher speeds on the disc with 4%Cr than at slower speeds on the disc with Ti added. This indicates that the addition of Ti enhances the tribological behaviour of rollers because the disc with Ti additive is characterised by carbonitrades precipitated in a refined tempered martensitic matrix. Coarse carbides characterise the 4%Cr disc materials. Surface defects of the work rolls, including banding, spalling, marking and welding in a cold strip plant, were investigated. It was found that early failures principally resulted from operational factors and roll material off-specification micro-structure defects rather than wear. It is recommended that different grades materials of the roll and strip with different roughness and hardness to be tested and studied on the evolution and tribological behaviour of roll surfaces in the future.
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Li, Yong 1974. "The economic effects of surface transport deregulation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/34527.
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Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2002.Includes bibliographical references (p. 71-72).
Over the past two decades, the deregulation of surface transport at both national and international levels has gathered momentum, particularly within the United States and European Union. The structural and performance changes associated with transport deregulation generated substantial redistribution of wealth among carriers, labor, . shippers, -and final customers and dramatically altered the costs and organization of transportation services. Many of these consequences were anticipated in the debate over deregulation; others have emerged during the regulatory transition. In general, economic regulation has led to net social benefits. This thesis will discuss the origin of transportation regulation and the forces for regulatory reform. The effects of the removal of economic control are assessed. It also examines the issues emerging after the deregulation and possibility for re-regulation in an effort to enhance safety and reduce the environmental impact of surface transport.
by Yong Li.
S.M.
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Söderström, Andreas. "Memory Efficient Methods for Eulerian Free Surface Fluid Animation." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60852.
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This thesis focuses on improving and extending the available toolset for Eulerian, i.e. grid based, free surface fluid animation and level set based surface tracking in the context of computer graphics and visual effects. More specifically three novel methods are presented each aimed towards reducing the amount of computer memory required for producing high resolution animations of incompressible free surface fluids. Each method is primarily developed for, but not limited to, the popular Stable Fluids method. Eulerian free surface fluid animation has historically required a large amount of computer memory, especially when high resolution results are desired. This problem has recently been addressed through the development of dynamic computational grids like the Dynamic Tubular Grid (DT-Grid) for level set computations. However, when animating free surface fluids a large amount of tracker particles are often added to the level set geometry in order to provide more accurate tracking of fluid surfaces. As a result the particle level set (PLS) method typically requires two orders of magnitude more memory than a DT-Grid level set. In order to reduce the gap in memory requirement between the level set and the particles this thesis introduces a fast and efficient compression method for such tracker particles. This compression is optionally combined with a specialized external memory algorithm that allows particle and level set data to be efficiently streamed back and forth between primary memory and secondary storage devices such as hard disk drives. The particle compression scheme is able to reduce the size of a DT-Grid particle level set by more than 65% while only inducing a 5% penalty to performance. If combined with the external memory algorithm particle level sets of virtually any size and resolution can be used in free surface fluid animations. The induced performance penalty of the combined scheme depends on the performance of the external storage device, however when using a traditional hard disk drive a 70% increase in simulation time was measured. This thesis also presents a purely Eulerian alternative to the PLS method through the introduction of a dual resolution level set representation. The method replaces the tracker particles with a level set of higher resolution, thus significantly increasing surface tracking accuracy compared to the unaided level set. The scheme is able to produce high quality results using up to 94% less memory than a PLS. The core component of the method is the Spatially Adaptive Morphology (SAM) filter which connects the high resolution representation of the level set with the lower resolution fluid, thus providing plausable animation also for small and/or thin surface features. A sheet preserving extension to the SAM filter is also presented that is able to preserve thin sheets of fluid indefinitely if so desired. Although this method adds mass to the simulation it is highly useful for animating phenomena like splashes, fountains and waterfalls. The final method presented in this thesis concerns the efficient local animation of oceans and other very large free surface fluids.For such scenarios large amounts of memory and computation time can be saved by only computing accurate fluid physics in a local fluid region immediately surrounding a point of interest. The fluid outside this region can then be animated using less accurate but significantly faster and less memory demanding models. However, for this approach to be accurate the local fluid must be contained in such a way that it behaves as if still part of a larger fluid. This thesis enables the local simulation of a larger body of fluid by introducing three different non-reflective boundary conditions for free surface fluid animation using a modified Stable Fluids method. Two simple wave dampening boundaries are presented as well as a significantly more advanced wave absorbing boundary based on the Perfectly Matched Layer (PML) approach. All three boundaries are shown to be effective in preventing wave reflection given large enough boundary regions. However the PML boundary is significantly more efficient, typically absorbing waves at a fraction of the distance required by the other two methods.
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Zhang, Xieqiu. "Scanning tunneling microscopy study : from clean surface to surfaces adsorbed with atom/cluster or metallic island /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20ZHANG.
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Gruetzmann, Anna [Verfasser]. "Wireless ECG Sensor in Surface Acoustic Wave Transponder Technology / Anna Gruetzmann." München : Verlag Dr. Hut, 2010. http://d-nb.info/1009484524/34.
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De, Silva Eugene. "Intensified plasma assisted processing : a novel process in surface coating technology." Thesis, Manchester Metropolitan University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366231.
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Peng, Eileen X. (Eileen Xiao Fei) 1980. "A technical evaluation of a novel cell-surface cytokine detection technology." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17039.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003.Includes bibliographical references (leaves 65-67).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Hall thrusters have become a tempting alternative to traditional chemical propulsion systems due to the great mass savings they provide through high specific impulses. However, a major stumbling block to their widespread integration is uncertainty about the thruster plume's interaction with spacecraft components. While in-space data is difficult to collect, much experimental data from vacuum tank tests is readily available. Effectively taking advantage of this wealth requires understanding of the effects from imperfect ground test conditions. A previous plume model, Qasi3, has been upgraded to better simulate the vacuum tank environment primarily through improvements to the source model, the collision method, and the sputtering method. The code is now more accurate and provides insight into phenomena such as background pressure consequences. sputtering and sputtered material deposition.
by Eileen Peng.
M.Eng.
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Robertson, Andrew J. "Extended surface flow and heat transfer studies." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302219.
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Sophian, Ali. "Characterisation of surface and sub-surface discontinuities in metals using pulsed eddy current sensors." Thesis, University of Huddersfield, 2003. http://eprints.hud.ac.uk/id/eprint/6916/.
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Due primarily to today's rigorous safety standards the focus of non-destructive testing (NDT) has shifted from flaw detection to quantitative NIDT, where characterisation of flaws is the objective. This means information such as the type of flaw and its size is desired. The Pulsed Eddy Current (PEC) technique has been acknowledged as one of the potential contenders for providing this additional functionality, due to the potential richness of the information that it provides. The parameters mainly used to obtain information about the detected flaws are the signal's peak height and arrival time. However, it has been recognised that these features are not sufficient for defect classification. In this research, based on a comprehensive literature survey, the design of PEC systems and the interpretation of PEC signals, mainly for flaw classification, are studied. A PEC system consisting of both hardware and software components has been designed and constructed to facilitate the research work on PEC signal interpretation. After a comparative study of several magnetic sensing devices, probes using Hall device magnetic sensors have also been constructed. Some aspects related to probe design, such as coil dimensions and the use of ferrite core and shielding have also been studied. A new interpretation technique that uses the whole part of PEC responses and is able to produce more features has been proposed. The technique uses Principal Component Analysis (PCA) and Wavelet Transforms, and attempts to find the best features for discrimination from extracted time and frequency domain data. The simultaneous use of both temporal and spectral data is a logically promising extension to the use of time domain only with the signal-peak-based technique. Experiments show that the new 1 technique is promising as it performs significantly better than the conventional technique using peak value and peak time of PEC signals in the classification of flaws. A hierarchical structure for defect classification and quantification has been presented. Experiments in the project have also shown that the signal-peak-based technique cannot be used for flaw detection and characterisation in steels, both with and without magnetisation. The new proposed technique has shown to have potential for this purpose when magnetisation is used. The new technique proposed in the report has been successfully used for ferromagnetic and non-ferromagnetic materials. It has also been demonstrated that the new proposed technique performs better in dynamic behaviour tests, which shows its better potential for on-line dynamic NDT inspection which is required in many industrial applications. In addition to testing calibrated samples with different discontinuities, a study case using an aircraft lap joint sample from industry has further supported the statement regarding the potential of the new technique.
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Bhave, Aniket. "A leaded and lead-free solder paste evaluation screening procedure." Diss., Online access via UMI:, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1425610.
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Naseer, Shahid Mohammad. "Shaping surface acoustic waves for cardiac tissue engineering." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7740/.
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The heart is a non-regenerating organ that gradually suffers a loss of cardiac cells and functionality. Given the scarcity of organ donors and complications in existing medical implantation solutions, it is desired to engineer a three-dimensional architecture to successfully control the cardiac cells in vitro and yield true myocardial structures similar to native heart. This thesis investigates the synthesis of a biocompatible gelatin methacrylate hydrogel to promote growth of cardiac cells using biotechnology methodology: surface acoustic waves, to create cell sheets. Firstly, the synthesis of a photo-crosslinkable gelatin methacrylate (GelMA) hydrogel was investigated with different degree of methacrylation concentration. The porous matrix of the hydrogel should be biocompatible, allow cell-cell interaction and promote cell adhesion for growth through the porous network of matrix. The rheological properties, such as polymer concentration, ultraviolet exposure time, viscosity, elasticity and swelling characteristics of the hydrogel were investigated. In tissue engineering hydrogels have been used for embedding cells to mimic native microenvironments while controlling the mechanical properties. Gelatin methacrylate hydrogels have the advantage of allowing such control of mechanical properties in addition to easy compatibility with Lab-on-a-chip methodologies. Secondly in this thesis, standing surface acoustic waves were used to control the degree of movement of cells in the hydrogel and produce three-dimensional engineered scaffolds to investigate in-vitro studies of cardiac muscle electrophysiology and cardiac tissue engineering therapies for myocardial infarction. The acoustic waves were characterized on a piezoelectric substrate, lithium niobate that was micro-fabricated with slanted-finger interdigitated transducers for to generate waves at multiple wavelengths. This characterization successfully created three-dimensional micro-patterning of cells in the constructs through means of one- and two-dimensional non-invasive forces. The micro-patterning was controlled by tuning different input frequencies that allowed manipulation of the cells spatially without any pre- treatment of cells, hydrogel or substrate. This resulted in a synchronous heartbeat being produced in the hydrogel construct. To complement these mechanical forces, work in dielectrophoresis was conducted centred on a method to pattern micro-particles. Although manipulation of particles were shown, difficulties were encountered concerning the close proximity of particles and hydrogel to the microfabricated electrode arrays, dependence on conductivity of hydrogel and difficult manoeuvrability of scaffold from the surface of electrodes precluded measurements on cardiac cells. In addition, COMSOL Multiphysics software was used to investigate the mechanical and electrical forces theoretically acting on the cells. Thirdly, in this thesis the cardiac electrophysiology was investigated using immunostaining techniques to visualize the growth of sarcomeres and gap junctions that promote cell-cell interaction and excitation-contraction of heart muscles. The physiological response of beating of co-cultured cardiomyocytes and cardiac fibroblasts was observed in a synchronous and simultaneous manner closely mimicking the native cardiac impulses. Further investigations were carried out by mechanically stimulating the cells in the three-dimensional hydrogel using standing surface acoustic waves and comparing with traditional two-dimensional flat surface coated with fibronectin. The electrophysiological responses of the cells under the effect of the mechanical stimulations yielded a higher magnitude of contractility, action potential and calcium transient.
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Bathawab, Fatma Mirfat. "Engineering surface mobility to direct stem cell fate." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8110/.
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Since the first contact and fusion of an egg and sperm and throughout development, a cell lives a life of constant communication with its environment. Cells interact with the external environment via a layer of proteins and respond to not only biochemical cues but also physical properties including stiffness and topography of adjacent surfaces. However, even though polymeric biomaterials have been described as one of the cornerstones of tissue engineering, the effect of an intrinsic polymer property known as mobility on cell behaviour is poorly characterised. Mobility is a physical property of polymers inversely proportional to the glass transition temperature (Tg); the temperature at which polymers undergo a transition between a rubbery viscous state to a glassy brittle solid. Therefore, films of four poly(alkyl acrylates) with similar surface chemistry but different glass transition temperatures achieved by varying branch chain lengths (1, 2, 4 or 6 methyl groups) were used in this work to investigate the role of polymer mobility on cell behaviour. I verified using atomic force microscopy the similarity in topography and stiffness between the four substrate surfaces and ascertained that fibronectin molecules adsorb in a globular conformation on the polymer with the shortest side chain (1 methyl group) compared with a more extended conformation on the rest of the polymers. My study of the fibronectin coatings using fluorescence recovery after photobleaching (FRAP) on the different polymer surfaces suggested that the mobility of the polymer substrate is translated to the interfacial protein layer. This interesting finding highlighted a possible pathway for cells cultured on fibronectin coated polymer surfaces to detect the underlying polymer mobility via the fibronectin coating. The interaction of cells with surfaces occurs via membrane proteins which interact with specific structural sites within extracellular matrix proteins; these include the cell binding site (RGD: Arginine Glycine Aspartic acid amino acid motif) and the Synergy site (PHSRN: Proline Histidine Serine Asparagine amino acid motif). My ELISA analyses indicated a higher exposure of these important cell-binding sites on the more extended fibronectin compared with the globular one however, this did not correlate to the mobility of polymers or the mobility of the fibronectin layer. This was also the case for myogenic cell differentiation, which was indiscriminately higher on polymers with extended fibronectin, however, cytoskeletal contractility was found to play an essential role in the myogenic differentiation of cells on these polymers in a mobility dependent manner. We then sought to understand the role of 21 mobility in modulating osteogenic differentiation of human MSCs in the presence and absence of stimulation with BMP-2. The Fibronectin network-forming polymer with the lowest mobility (side chain of 2 methyl groups) induced the highest expression of osteogenic markers in the absence of BMP-2 stimulation. My mechanistic studies using specific inhibitors also revealed that the Erk1/2 pathway was required for this increase in osteogenic markers, while contractility, unlike in myogenesis produced only minimal effects on osteogenic differentiation. In this set of polymers, mobility increases with side chain length, while all the polymers with more than one methyl group in their side chain induced the independent formation fibronectin networks upon adsorption. The polymer with two methyl groups in its side chain is characterised with the lowest mobility among the three fibrillogenesis - inducing polymers, and the highest expression of osteogenic markers in the absence of BMP-2. In the presence of BMP-2, smad phosphorylation was also higher on this polymer suggesting a combined synergistic effect towards osteogenic differentiation provided by the simultaneous activation of the Erk1/2 pathway and high phosphorylation of smad1/5/8. My observations suggest that fibronectin fibrils coating a polymer with low mobility may be most suited for osteogenic differentiation of hMSCs by simultaneously exposing cell-binding sites to a higher degree. Thus, inducing Erk1/2 signalling and presenting BMP-2 in a manner that stimulates the highest phosphorylation of smad1/5/8 hence achieving a stronger synergistic effect on the overall expression of osteogenic markers. The findings from this work strongly support previous studies suggesting that polymer mobility is a subtle change in the substrate with significant downstream biological significance and is crucial to understand to improve the application of polymeric biomaterials.
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Gupta, Barun Shankar. "Development of a coating technology for wood plastic composites." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/b_gupta_082806.pdf.
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Roberts, David E. Peltonen Jeffry M. Ozeck David J. "Baseline assessment of information technology contracts funded by Commander, Naval Surface Forces." Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/MBAPR/2010/Mar/10Mar%5FRoberts%5FMBA.pdf.
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"Submitted in partial fulfillment of the requirements for the degree of Master of Business Administration from the Naval Postgraduate School, March 2010."Advisor(s): Cook, Glenn. ; Simon, Cary. "March 2010." "MBA Professional report"--Cover. Description based on title screen as viewed on May 18, 2010. Author(s) subject terms: Information Technology, Baseline Assessment, Commander, Naval Surface Forces, CNSF Includes bibliographical references (p. 91-92). Also available in print.
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Rosli, M. H. "Surface defect characterisation using non-contact ultrasound." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/59439/.
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Electromagnetic acoustic transducers (EMATs) have been used as a non-contact ultrasound approach for detecting and characterising surface defects in aluminium bars and billet. The characterisation was made from understanding the interaction of broadband Rayleigh surface waves with surface crack growing normal or inclined to the sample surface, based on rolling contact fatigue (RCF) cracks in rail tracks. The interaction with normal cracks have been previously reported. For inclined cracks, mode conversion of Rayleigh waves to Lamb-like waves occur in the wedge section formed by the crack, resulting in strong and prominent enhancement in the signal detected. This is confirmed by finite element analysis (FEA) models and Lamb waves arrival times calculation. Signal enhancement from the interaction creates features in B-scan images, and they have been used for initial crack classifications. Then, a number of analyses were performed to estimate the crack inclination, and accurately determine the crack vertical depth. A feature extraction and image classification program based on genetic programming have been developed (through a collaboration work) to perform automated classification on the B-scans. The program produces more than 90% accuracy using the experimental data set. The viability of EMATs to detect and fully characterise narrow cracks have been investigated through experiments using laser interferometer and comparison with EMATs measurements. The results confirmed that narrow cracks can be detected with EMATs, with initial classification (in B-scans) to normal/inclined. However, the depth sizing may not be accurate, and suggestion for better designs of EMATs have been made. FEA models have been used to study the interaction of the Rayleigh waves with branched cracks. Interesting results are observed in terms of Rayleigh waves reflections, which helps to determine the presence of a branch on RCF-like cracks. A method has been proposed for calculating the length of the branch, following a number of analyses.
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Atefi, Ehsan. "Aqueous Biphasic 3D Cell Culture Micro-Technology." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1443112692.
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Lamar, Andrew. "Bounding surface plasticity theory with backstress decomposition and material memory." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/15857.
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Hassan, Mothana A. "Surface profile measurement using spatially dispersed short coherence interferometry." Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/28343/.
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Modern manufacturing processes require better quality control of the manufactured products at a faster rate, for achieving good throughput. This is increasing the need for process-oriented precision metrology capable of providing faster inspection and yielding valuable feedback to the manufacturing system for quality control of the manufactured products. Over the past twenty years optical sensors have emerged as a preferred method for the measurement applications in manufacturing automation, owing to some inherent advantages, such as high speed, high resolution, non-contact operation, and low cost. Improved online optical sensors for surface measurement would enable incorporating measuring systems into production processes and machines, improving the production performance and the quality of products, which is highly desired in many high/ultraprecision manufacturing applications. This thesis presents a novel spatially dispersed short coherence interferometry (SDSCI) sensor system for online surface measurement applications on the nanoscale. The SDSCI sensor system uses a low-cost broadband super-luminescent diode (SLD) with an emission bandwidth of 25 nm. Two measurement methods, phase shifting interferometry and Fourier transform for surface profile measurements, have been investigated in this study. The metrology sensor system incorporated the Michelson interferometer configuration with an optical probe in the measurement arm, while the reference arm had a mirror with a piezo-electric transducer. The technique involves surface scanning by spatially dispersing the broadband light using a reflective grating and a scan lens, and recording the resulting interferogram by using a high-speed spectrometer. The first measurement method involved investigations of implementation of phase shifting interferometry and the Carré algorithm for phase retrieval from the measured phase-shifted interferograms for profile measurements. Standard diamond turned multi-stepped and NPL artefact samples with 550-nm and 100-nm-high steps, respectively, were measured and confirmed the capability of the measurement sensor. The measurement speed of this technique was limited by the spectrometer speed and by the piezo-electric transducer movement. The optimised system has a measurement time of 1s. The second method was then investigated based on the Fourier transform profilometry technique for further increasing the measurement speed of the sensor device, as it required a single-shot interferogram, alleviating the need of any phase shifting. With increased measurement speed, this technique further reduced the problem of environmental noise inherent to all interferometer-based systems. Similar artefacts were measured by using this technique for evaluating its applicability for surface profile measurements. Once the sensor system was optimised and calibrated, the resulting open-space system could be further miniaturised into a compact sensor system by using optical fibres with a remote probe connected via a fibre link for use in embedded metrology applications. This method will be very beneficial in online inspection of samples in rollto-roll manufacturing processes, where the measurand is constantly moving. An example of such a measurement challenge is detection of defects on vapour barrier films formed by depositing an aluminium oxide layer several tens of nanometres thick on a flexible polymer substrate. Effective detection and characterisation of defects in this layer requires a single-shot approach with nanometre-scale vertical resolution.
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Barnett, David L. "EVALUATION OF FIRE-FIGHTING HELMET SURFACE TECHNOLOGY FOR HIGH RADIANT HEAT APPLICATIONS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/305.
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Protective helmets used by fire-fighters must be designed to minimize the amount of heat transferred to the users head while providing durability, comfort, and affordable costs. This thesis highlights the evaluation of new helmet technology specifically tailored to high radiant heat environments to advance the state-of-the-art in head protection for this application. The research focused on the assessment of the outer shells of helmets and the properties of the surfaces. The development included the evaluation of radiation heat transfer, in a laboratory environment, to various helmet shell surface constructions. Industry standards were considered, and critiqued. Experiments were designed to isolate critical design variables for measurement and evaluation. Custom, purpose-built laboratory apparatus for testing helmets were designed, explained and utilized in the testing of specimens. Additionally, market demands for firefighting helmets were explored. Helmet durability was specifically addressed with abrasion criteria established and the reflectivity effects of the abraded surfaces evaluated. Resulting from this study, new surface technologies were identified for possible development in future helmet designs. Various surface materials, finishes, and coatings were compared and contrasted to current industry state-of-the-art equipment. The knowledge discovered further advanced modern head protection science in aim of increased safety and performance of fire-fighting personnel.
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Huang, Pi-wen, and 黃碧雯. "Surface Mount Technology In Schedule Problem." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/62640614803898176076.
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碩士元智大學
工業工程與管理學系
85
In electroics industry, there is a need to boost production efficiency and enhance The capability of the printed circuit board ,i.e. to install more components and to cut down the installation path 。And , by cutting down cost the production means to increase more profit。 The capability to develop surface mount component is well-established in Taiwan . however , the capabilities of production process and management techniques need to of further improved。In the thesis , Group Technology is applied for classifying each mounting head. And The precedence constrained branch and Bound technique is applied to analysis the complexities of the problem。Then , a heuristic procedure , based on depth-first search and Beam search method is develop to solve the problem。It is concluded that, according to the result of experiments ,this algorithm is applicable to the industry mounting system and could be extended to other similar manufactory problem。
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Mathews, Joshua Benjamin. "Micro-probe for physical and chemical surface analysis /." 2001. http://www.library.umaine.edu/theses/theses.asp?Cmd=abstract&ID=CHE2001-001.
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吳蕙芬. "Repair Process Improvement—Surface Mount Technology Line." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/21100059705174055549.
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碩士國立清華大學
工業工程與工程管理學系碩士在職專班
100
The study proposed a process improvement analysis on fail module from SMT (Surface Mount Technology) production line. This paper examines the three major factors comprising the process improvement, repair cost analysis and repair age determination. The first part is the process improvement by fail parts, how to categorize the fail units by different failure mode, and apply the test raw data of CARD test to improve the first repair ratio and reduce the repair cycle time as well. The second parts is to analysis the linkage of repair time and its repair cost, collect the prime cost of rework single module and the increasing rework cost along with repair times, then compare the total cost with its selling price to examine current repair times. The third part is to find out the optimal repair age for single module by the way of decision tress, with its analysis result and it can determine the optima repair age by collecting production record over six months which cover the repair age , amount of rework, repair yield , test yield and repair cost . This proposal provides (1) the way to improve repair yield and reduce the amount of un-rework lots by real case。(2) the way to determine the optima repair age for engineer reference.
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Shishkin, Dimitri V. "Development of icejet-based surface processing technology." Thesis, 2002. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2002-087.
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Shivapooja, Phanindhar. "Active Surface Deformation Technology for Management of Marine Biofouling." Diss., 2016. http://hdl.handle.net/10161/12813.
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Biofouling, the accumulation of biomolecules, cells, organisms and their deposits on submerged and implanted surfaces, is a ubiquitous problem across various human endeavors including maritime operations, medicine, food industries and biotechnology. Since several decades, there have been substantial research efforts towards developing various types of antifouling and fouling release approaches to control bioaccumulation on man-made surfaces. In this work we hypothesized, investigated and developed dynamic change of the surface area and topology of elastomers as a general approach for biofouling management. Further, we combined dynamic surface deformation of elastomers with other existing antifouling and fouling-release approaches to develop multifunctional, pro-active biofouling control strategies.
This research work was focused on developing fundamental, new and environment-friendly approaches for biofouling management with emphasis on marine model systems and applications, but which also provided fundamental insights into the control of infectious biofilms on biomedical devices. We used different methods (mechanical stretching, electrical-actuation and pneumatic-actuation) to generate dynamic deformation of elastomer surfaces. Our initial studies showed that dynamic surface deformation methods are effective in detaching laboratory grown bacterial biofilms and barnacles. Further systematic studies revealed that a threshold critical surface strain is required to debond a biofilm from the surface, and this critical strain is dependent on the biofilm mechanical properties including adhesion energy, thickness and modulus. To test the dynamic surface deformation approach in natural environment, we conducted field studies (at Beaufort, NC) in natural seawater using pneumatic-actuation of silicone elastomer. The field studies also confirmed that a critical substrate strain is needed to detach natural biofilm accumulated in seawater. Additionally, the results from the field studies suggested that substrate modulus also affect the critical strain needed to debond biofilms. To sum up, both the laboratory and the field studies proved that dynamic surface deformation approach can effectively detach various biofilms and barnacles, and therefore offers a non-toxic and environmental friendly approach for biofouling management.
Deformable elastomer systems used in our studies are easy to fabricate and can be used as complementary approach for existing commercial strategies for biofouling control. To this end, we aimed towards developed proactive multifunctional surfaces and proposed two different approaches: (i) modification of elastomers with antifouling polymers to produce multifunctional, and (ii) incorporation of silicone-oil additives into the elastomer to enhance fouling-release performance.
In approach (i), we modified poly(vinylmethylsiloxane) elastomer surfaces with zwitterionic polymers using thiol-ene click chemistry and controlled free radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionalities. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. In approach (ii), we incorporated silicone-oil additives in deformable elastomer and studied synergistic effect of silicone-oils and surface strain on barnacle detachment. We hypothesized that incorporation of silicone-oil additive reduces the amount of surface strain needed to detach barnacles. Our experimental results supported the above hypothesis and suggested that surface-action of silicone-oils plays a major role in decreasing the strain needed to detach barnacles. Further, we also examined the effect of change in substrate modulus and showed that stiffer substrates require lower amount of strain to detach barnacles.
In summary, this study shows that (1) dynamic surface deformation can be used as an effective, environmental friendly approach for biofouling control (2) stretchable elastomer surfaces modified with anti-fouling polymers provides a pro-active, dual-mode approach for biofouling control, and (3) incorporation of silicone-oils additives into stretchable elastomers improves the fouling-release performance of dynamic surface deformation technology. Dynamic surface deformation by itself and as a supplementary approach can be utilized biofouling management in biomedical, industrial and marine applications.
Dissertation
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Zhang, Zhiyong. "Analysis of some biosensor models with surface effects." Phd thesis, 2009. http://hdl.handle.net/10048/668.
Full textAbstract:
Thesis (Ph. D.)--University of Alberta, 2009.Title from pdf file main screen (viewed on Dec. 22, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Applied Mathematics, Department of Mathematical and Statistical Sciences, University of Alberta." Includes bibliographical references.
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Shih-Ping, Yang, and 楊士平. "Component Placement Sequence Strategies in Surface Mount Technology." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/08171262278744458764.
Full textAbstract:
碩士開南管理學院
航運與物流管理系碩士班
93
The surface mount technology (SMT) is the technology for making the printed circuit board to mount the surface mount component on the printed circuit board and composes a complete circuit finally. The automatically mount machine operation is the bottleneck of surface mount technology in general. To balance the production operation and reduce operation time, it must consider the interaction influence between all equipments when setting the component placement sequence. The component sequence is maped out by following the past experience or historical material in general. This research analyzes the operation characteristics focus on the base of MSH-3 high speed mount machine. Categorizing the component placement operation as “component placement sequence on printed circuit board” and “component material position assignment on material trough”, this research construct a minimum waiting delay time model for component placement. For solving better component placement sequence promptly and simply, this research develops some strategies to find approximate solution. In view of the improvement rate, there is near 60% saving on test case, it reveals that the solving strategies of this research can promote the component placement operation efficiency.