Dissertations / Theses on the topic 'Characterisation techniques'
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1
Gopinathan, Navin. "Development of catalyst characterisation techniques." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.571865.
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Standard catalyst characterisation techniques such as gas adsorption porosimetry and mercury porosimetry only account for some of the physical heterogeneity of the catalyst surface. They completely ignore the chemical heterogeneity present and in most cases consider pores present in the medium to be independent of each other. Thus, most results of characterisation (pore space descriptors such as BET surface area, BJH pore size distribution, mercury porosimetry surface area, etc.) are not accurate. This has been a major issue that remains to be resolved during the characterisation of fresh and coked catalysts. In this thesis, the use of a multi-component adsorption system is recommended as a step-change solution to this limitation. Two approaches are adopted. Firstly, integrated nitrogen-waternitrogen gas adsorption experiments are performed on fresh and coked catalysts. This established the significance of pore coupling by showing the presence of advanced adsorption. The method also helped to determine the location of coke deposits within catalysts and indicated that water vapour adsorption was a good probe to understand the sites responsible for coking. Secondly, coadsorption of immiscible liquids – cyclohexane and water – was performed on fresh and coked catalysts following which the displacement of cyclohexane by water was studied using NMR relaxometry and diffusometry. This novel approach takes the wettability of the surface into consideration, unlike the former methods. It is therefore a method that accounts for the chemical heterogeneity of the surface. It also helped determine the location of coke within catalysts. The different approaches are presented in the context of combustion of heavy oil in bitumen reservoirs, and the use of supercritical conditions that help to dissolve coke precursors in the isomerisation of 1-hexene. Thus, the solutions provided in this thesis are directions in which catalyst characterisation, especially distinguishing fresh and coked catalysts, and other porous materials, must be carried out.
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Fermann, Martin. "Characterisation techniques for special optical fibres." Thesis, University of Southampton, 1988. https://eprints.soton.ac.uk/404728/.
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Special optical fibres are introduced with the emphasis on rare-earth-doped fibres and fibres with crystal-like properties. Characterisation techniques for these types of fibre are discussed and several applications are described. In particular, optical time-domain reflectometry is used to demonstrate a distributed temperature sensor based on the temperature dependence of the absorption in rare-earth-doped fibres. Further, energy transfer between ytterbium and erbium is characterised and an erbium fibre laser sensitised with ytterbium is demonstrated. Finally, techniques for the creation of crystal-like properties in optical fibres are developed and second-order nonlinear phenomena in these fibres are analysed both experimentally and theoretically.
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Santerne, A., J. P. Beaulieu, Ayala B. Rojas, I. Boisse, E. Schlawin, J. M. Almenara, V. Batista, et al. "Spectroscopic characterisation of microlensing events." EDP SCIENCES S A, 2016. http://hdl.handle.net/10150/622445.
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The microlensing event OGLE-2011-BLG-0417 is an exceptionally bright lens binary that was predicted to present radial velocity variation at the level of several km s(-1). Pioneer radial velocity follow-up observations with the UVES spectrograph at the ESO-VLT of this system clearly ruled out the large radial velocity variation, leaving a discrepancy between the observation and the prediction. In this paper, we further characterise the microlensing system by analysing its spectral energy distribution (SED) derived using the UVES spectrum and new observations with the ARCoIRIS (CTIO) near-infrared spectrograph and the Keck adaptive optics instrument NIRC2 in the J, H, and Ks-bands. We determine the mass and distance of the stars independently from the microlensing modelling. We find that the SED is compatible with a giant star in the Galactic bulge and a foreground star with a mass of 0.94 +/- 0.09 M-circle dot at a distance of 1.07 +/- 0.24 kpc. We find that this foreground star is likely the lens. Its parameters are not compatible with the ones previously reported in the literature (0.52 +/- 0.04 M-circle dot at 0.95 +/- 0.06 kpc), based on the microlensing light curve. A thoughtful re-analysis of the microlensing event is mandatory to fully understand the reason of this new discrepancy. More importantly, this paper demonstrates that spectroscopic follow-up observations of microlensing events are possible and provide independent constraints on the parameters of the lens and source stars, hence breaking some degeneracies in the analysis. UV-to-NIR low-resolution spectrographs like X-shooter (ESO VLT) could substantially contribute to this follow-up efforts, with magnitude limits above all microlensing events detected so far.
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Pickering, Edmund Ian Marcus. "Mechanical characterisation of nanowires through resonance techniques." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/123008/1/Edmund_Pickering_Thesis.pdf.
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This thesis uses the mechanical resonance technique to investigate and characterise the mechanical behaviour of nanowires. While previous work has mainly focused on simple, uniform nanowires, this thesis extends the resonance technique to incorporate more complex morphologies. Specifically, tapered nanowires with surface effects and curved nanowires with irregular cross-sections were investigated through experiments and modelling. This works will aid in advancing the pace of nanowire development by extending the resonance technique to describe such nanowire morphologies.
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Tsiamis, Andreas. "Electrical test structures and measurement techniques for the characterisation of advanced photomasks." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4296.
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Existing photomask metrology is struggling to keep pace with the rapid reduction of IC dimensions as traditional measurement techniques are being stretched to their limits. This thesis examines the use of on-mask probable electrical test structures and measurement techniques to meet this challenge and to accurately characterise the imaging capabilities of advanced binary and phase-shifting chrome-on-quartz photomasks. On-mask, electrical and optical linewidth measurement techniques have highlighted that the use of more than one measurement method, complementing each other, can prove valuable when characterising an advanced photomask process. Industry standard optical metrology test patterns have been adapted for the direct electrical equivalent measurement and the structures used to characterise different feature arrangements fabricated on standard and advanced photomasks with proximity correction techniques. The electrical measurements were compared to measurements from an optical mask metrology and verification tool and a state-of-the-art CD-AFM system and the results have demonstrated the capability and strengths of the on-mask electrical measurement. For example, electrical and AFM measurements on submicron features agreed within 10nm of each other while optical measurements were offset by up to 90nm. Hence, electrical techniques can prove valuable in providing feedback to the large number of metrology tools already supporting photomask manufacture, which in turn will help to develop CD standards for maskmaking. Electrical test structures have also been designed to enable the characterisation of optical proximity correction to characterise right angled corners in conducting tracks using a prototype design for both on-mask and wafer characterisation. Measurement results from the on-mask structures have shown that the electrical technique is sensitive enough to detect the effect of OPC on inner corners and to identify any defects in the fabricated features. For example less than 10 (5%) change in the expected resistance data trends indicated a deformed OPC feature. Results from on-wafer structures have shown that the correction technique has an impact on the final printed features and the measured resistance can be used to characterise the effects of different levels of correction. Overall the structures have shown their capability to characterise this type of optical proximity correction on both mask and wafer level. Test structures have also been designed for the characterisation of the dimensional mismatch between closely spaced photomask features. A number of photomasks were fabricated with these structures and the results from electrical measurements have been analysed to obtain information about the capability of the mask making process. The electrical test structures have demonstrated the capability of measuring tool and process induced dimensional mismatches in the nanometer range on masks which would otherwise prove difficult with standard optical metrology techniques. For example, electrical measurements detected mismatches of less than 15nm on 500nm wide features.
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Ramble, David Gary. "Characterisation of bubbles in liquids using acoustic techniques." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390369.
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Cowey, Lisa. "Characterisation techniques and critical parameters for anisotropic superconductors." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314865.
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Hobson, David Mark. "Characterisation of rice grains using digital imaging techniques." Thesis, University of Kent, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509657.
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Boonkhao, Bundit. "On-line characterisation techniques for manufacture of nanomaterials." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540791.
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Schuller, Timothy Adam. "Gallium nitride sensor devices fabrication techniques and characterisation." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549688.
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A saccharide sensor was fabricated using an AlGaN/GaN heterostructure structure and a boronic-acid containing receptor. Parallel to this, photoelectrochemical (PEC) etching of Gallium Nitride (GaN) was employed both as a nanostructuring technique and as a method of rapid dislocation density enumeration. The device fabrication techniques necessary for the development of devices based on n-type GaN and its alloys were successfully implemented. A robust photolithographic mask capable of producing a variety of transistor and sensor structures was designed and fabricated. Surface Charge Lithography (SCL) was studied and implemented as a technique for the nanostructuring of n-type GaN. In contrast to previous work (where patterns with feature sizes down to 100nm were created¹), several shortcomings of the technique were noted and subsequently investigated: a failure to achieve the intended minimum feature size; elongation of features in the direction of FIB instrument rastering; and the loss of thin features perpendicular to the rastering direction. A pattern design scheme to overcome these shortcomings was proposed along with experimental improvements expected to alleviate such issues. A novel receptor molecule employing a phenylboronic acid (BAT) was synthesised and used to functionalise an AlGaN/GaN FET device, thereby creating an electronic saccharide sensor device. The response of the sensor to a panel of saccharides (fructose, galactose and glucose) was investigated, with the order of response confirming previous findings (decreasing from fructose to galactose to glucose). The device was found to have good stability prior to failure, indicating that this type of sensor device shows a great deal of potential for wider use. PEC etching was used as a technique for determining the dislocation density in two distinct GaN on sapphire structures with thick AlN buffer layers. The SRI sample (100nm of GaN with 500nm of AlN) had a dislocation density of 1.9±O.2xl0⁹cm-², while the SH2 sample (500nm of GaN with lOOnm of AIN) had approximately twice this density, at 3.8±O.2xl0⁹cm-². The differences are thought to primarily arise from the difference in AlN thickness.
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Watts, David Terence. "The characterisation of coals using image analysis techniques." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420359.
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Gardner, Michelle A. "Structural characterisation of porous carbons using scattering techniques." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282422.
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Darji, Rohit. "Characterisation of heterogeneous catalysts by electron-optical techniques." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627255.
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Davies, Stephen James. "Remote techniques for time-of-flight flaw characterisation." Thesis, University of Warwick, 1991. http://wrap.warwick.ac.uk/108293/.
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This thesis describes the investigations conducted into the characterisation of various defects within solids using laser - generation and interferometric detection of ultrasound. Laser - generated ultrasound has advantages over the more commonly used piezoelectric transducers in that it is a reproducible, wide bandwidth, non - contact source which, by using appropriate optics, can be focussed to a point or line source and easily scanned over a surface. Used in association with an interferometric detector enables the possibility of a remote inspection system which would be useful for some applications. The properties of such a system for the characterisation of both bulk and surface - breaking defects are ascertained. Part of the research project has been concerned with determining the properties of the ultrasound produced in various solids by different laser pulse profiles. The results obtained indicate that the risetime of the ultrasonic compression wave decreases with decreasing incident laser pulse risetime. However the mechanical and thermal properties of the irradiated solid also affects the risetime of the ultrasound. Modelling of the laser - solid interaction was undertaken to understand this phenomenon in more detail. The wide bandwidth nature of laser - generated ultrasound was used in the characterisation of bulk defects. This has involved determining, using an FFT algorithm, the phase change which occurs when laser - generated ultrasound is scattered from such defects. The aim of the investigation was to assess whether a particular type of defect has a unique phase change which will enable it to be classified. The experimental results obtained compared favourably with the results from theoretical modelling of ultrasonic scattering by defects. Finally the interaction of laser - generated Rayleigh ( surface ) waves with surface - breaking defects was considered. Various techniques for the characterisation of surface - breaking defects by analysis of data in the time and frequency domain were utilised. One such technique involved measurement of the Reflection and Transmission coefficients of various surface discontinuities. The phase change of the scattered Rayleigh wave was determined and compared to the theoretical data available. Also, a technique was established whereby certain features on the waveforms recorded on transmission of a Rayleigh wave through a surface - breaking defect could be used to determine the depth of the defect.
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Fisha, Phuti Cedric. "Characterisation of selected soil properties using remote sensing techniques." Thesis, University of Limpopo, 2019. http://hdl.handle.net/10386/2861.
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Thesis (M. Sc. (Soil Science)) --University of Limpopo, 2019Many conventional laboratory methods are used to characterise spatial and temporal variation of soil properties in order to understand soil quality for different purposes. Currently there is a high demand for accurate soil information by land users. Therefore there is a need to develop a rapid, inexpensive, non-destructive and accurate technique that could compensate or replace conventional laboratory methodologies. Remote sensing has the potential to serve as an alternative approach to characterise soil properties due to its advantages over conventional laboratory methods such as it is rapid, non-destructive and it has low cost. The objectives of this study were to: (i) evaluate the ability of proximal soil sensing to characterise soil properties namely organic matter, soil moisture content, macronutrients, soil texture, cation exchange capacity (CEC), and pH. (ii) Identify bands of relevance from proximal soil sensing (300-2400 nm) that can provide acceptable reflectance variation for different levels of selected soil properties. (iii) Evaluate the performance of models developed from multispectral space-borne image in characterising selected soil properties. In this study spectroradiometer (proximal sensor) and worldview 2 satellite images (space-borne) were the two remote sensing techniques used to collect information about soil at Syferkuil experimental farm of the University of Limpopo. Visible and near infrared spectral data of 98 soil samples were collected at the study site using Analytical spectral device (ASD) field spectroradiometer. Spectral reflectance from spectroradiometer and those extracted from worldview 2 satellite image were used to develop prediction models of selected soil properties using Partial least square regression (PLSR). Bands of relevance were also identified from PLSR models developed from spectral data acquired by spectroradiometer. The results showed that estimation accuracy of PLSR models developed using spectral data from proximal soil sensing were excellent (Category A) for clay, sand, soil organic matter (SOM), and soil moisture content, while good prediction accuracy (Category B) was observed for other soil properties such as silt, ammonium, nitrate, active acidity (pHw), calcium, magnesium, phosphorus, potassium, sulphur, CEC, and reserve acidity (pHKCl). Then, relevant bands which contributed greatly in the prediction of these soil attributes were selected from the electromagnetic spectrum, the range was from 451 nm to 2400 nm. These bands fall within visible, shortwave infrared and near-infrared x regions of electromagnetic spectrum. In addition all selected soil properties were approximately quantitatively estimated using spectral data from satellite image. Based on the results obtained it can be concluded that proximal soil sensing has the ability to predict selected soil properties with various accuracies and it can be used as an alternative technique to characterise soil properties of South African soils. Soil predicting models developed from proximal soil sensing data also showed that there are bands of relevance within spectral range of 451 nm to 2400 nm. However more work is required for space-borne sensing before it can be used as one of the soil characterisation methods since its prediction accuracy was low as compared to that of hyperspectral proximal soil sensing. Keywords: Space-borne sensing; proximal soil sensing; soil characterisation.
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McLoughlin, Sean Diego. "The characterisation of archaeological glasses using advanced analysis techniques." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/8272.
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Romans, James Alexander. "Multivariate Calibration Techniques for Spectroscopic Characterisation of Crude Oils." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506561.
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McAlister, John J. "Characterisation of basaltic weathering products by modern analytical techniques." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329424.
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Davies, Antony. "Characterisation and parameter extraction techniques for GaAs MESFET devices." Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241552.
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Daniels, Howard Robert. "Novel characterisation techniques for carbonaceous materials in the FEGTEM." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399632.
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Thring, Claire B. "Enhanced EMAT techniques for the characterisation of hidden defects." Thesis, University of Warwick, 2019. http://wrap.warwick.ac.uk/114456/.
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There is an industrial drive for the improved detection of sub-mm sized sur¬face breaking defects using non-destructive evaluation (NDE) methods [1]. Electromagnetic acoustic transducers (EMATs) are a non-contact NDE technique that utilise the generation and detection of Ultrasound using primarily Lorentz force mechanisms [2]. They are relatively safe and inexpensive, however, they suffer from low generation efficiency. The precise industrial drive for this work is improved ultrasonic crack detection of surface defects hidden by a thin metallic paint coating. The majority of standard ultrasonic techniques are not applicable as they require direct contact to the sample surface. Laser techniques, while non-contact, are still impeded by the coating, and eddy current techniques are difficult to implement due to interference from the metallic coating. EMATs are applicable, however their low generation efficiency limits the minimum defect that can be detected. This work presents improved resolution surface wave EMATs using geometric focusing for the detection of sub-mm sized surface breaking defects. Three main design types have been presented: a pseudo-pulse-echo focused meander-line EMAT, a pitch-catch focused racetrack EMAT and a pitch-catch focused linear EMAT. The first two designs have been fully characterised, finding the relations between coil geometry, focal point location and size, and the optimum operation frequencies [3, 4, 5]. Both designs have been used to size the lengths of a set of drilled calibration defects to accuracies of 10.5 and 10.4 mm respectively, and the pitch-catch design has been used to create a calibration curve for defect depth measurements. In addition, both designs have been used to map a pair of real surface breaking cracks in an aluminium billet sample to sub-mm resolution. The pitch-catch design has been used to detect a set of mm-size real thermal fatigue cracks in steel through a 40 - 60 ktm thick metallic paint coating. A four-coil EMAT design based on the pitch-catch focused racetrack EMAT has been built and demonstrated to detect surface breaking defects regardless of their surface orientation. Finally, the meander-line, racetrack, and linear coil design types have been compared based on their signal strength and their performance at lift-off from a sample surface. The meander-line designs have the strongest signal to noise ratios (SNR), with over 40 dB found when in contact with the sample, but the largest SNR loss with increased lift-off, reducing to 0 dB by 0.3 mm lift-off. The linear designs have the weakest SNRs, under 30 dB when in direct contact, but the smallest SNR loss with increased lift-off, dropping to 0 dB by around 1 mm, depending on the frequency of operation. This makes the linear coil designs optimal for situations requiring higher lift-off. Lower frequency designs are shown to perform better with increased lift-off regardless of the coil design, however, lower frequencies have less spatial resolution capabilities. A proposed linear-meander-line phased EMAT design is presented to generated 1 MHz signals but with the improved lift-off capabilities of the linear designs. This proves that surface wave EMATs can be optimised for surface wave detection of sub-mm defects through a metallic paint coating. While pseudo-pulse-echo focused meander-line EMATs are already in exsitence, there was previously no published work on their capabilities and full charaterisation. The other focused designs presented here are new designs in the field.
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Daley, T. E. "Advanced characterisation of catalytic materials using synchrotron radiation techniques." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1468758/.
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Heterogeneous catalysis is a large and important field of research, and is especially of interest to the project sponsors Johnson Matthey (JM). This EngD project focused on studying catalytic materials of interest to JM in order to investigate the metal support interaction and determine the effects of various reaction conditions. The key techniques used in this work are synchrotron radiation based, such as X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) as well as combinations of techniques. A variety of catalytic materials have been investigated using synchrotron X-ray techniques and conventional laboratory analytical techniques. Understanding these processes will allow for the tailoring of catalyst design and modification of support materials that will lead to improved and more efficient catalytic materials in the future. Supported platinum group metals were studied during reduction using in situ XAS. The materials were prepared through sequential deposition on an alumina support of first the platinum group metal then a ceria layer; this additional layer of ceria was deposited to cover the metal particles, limiting movement and gas transfer processes. The effect of the MSI on the reduction of Pd nanoparticles supported on a variety of inorganic materials in order to determine the structure of metal particles was also explored using in situ XAS. A combination of the LIII- and K-edge analysis was utilised to provide a better understanding of metal support interaction and the changes in the electronic structure for supported Pd nanoparticles. Other materials investigated include zinc oxide nanoparticles, which are important for a variety of applications due to their semi-conductor properties. Additionally AuCu bimetallic clusters were investigated in situ during reduction, calcination and during the catalytic oxidation of propene. The use of XAS allowed for the probing of the extent of the metal alloying and the effect on the propene catalysis.
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Angel-Smith, Sarah Jane. "Characterisation of diesel injector deposits using advanced analytical techniques." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50745/.
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Internal diesel injector deposits (IDIDs) have become a prolific issue in the last decade, increased number of incidences have occurred since the introduction of ultra-low sulfur diesel and biodiesel. The IDIDs have caused concerns for customers such as injector systems misfiring or blocking, increased emissions and fuel consumption. Interest into the origins of the deposits has steadily grown, with identified possible causes including contaminants, degraded additives, or thermal and pressure stresses of the engine. Most examples in previous studies only provide surface analysis of IDIDs, however, the surface only provides a relatively small part of the story. In order to understand how an IDID has formed the history needs to be explained, to do this the lower layers of the IDID need to be analysed. Outcomes of this research include the first example of focused ion beam and secondary ion mass spectrometry being used in combination to analyse IDIDs and clearly shows different chemical layers, demonstrating that these deposits are made up of multiple complex chemistries. Raman spectroscopy can provide graphitic content information for IDIDs giving evidence of formation however, a method to remove fluorescence from carbonaceous structures was first devised and validated in order to allow this to be performed. The jet fuel thermal oxidation test (JFTOT) has been proven to be an effective method of replicating deposits on comparison with IDIDs from failed field engines, and key chemistries have been identified for B20 biodiesel and ultra-low sulfur diesel (ULSD). This work has used existing analytical methods to understand IDIDs and found novel insights that have not been previously observed in the literature.
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Pandey, Lopa M. S. "Liner characterisation and leak detection using electrical resistivity techniques." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2018. https://ro.ecu.edu.au/theses/2159.
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The resistivity of soil ranges from 7-15 Ωm for Leachate #1 to 20-50 Ωm for Leachate #2. The resistivity decreases with an increase in the proximity to the leak point. Furthermore, the resistivity values obtained with water were nearly 10 times the values observed with landfill leachate as the leaching liquid. Based on the resistivity profiles of soil as observed at different time intervals, the method is found to be effective in determining leakages in the liner.
The test results have also been presented for the leakage of Bayer liquor obtained from aluminium manufacturing company in Western Australia. The resistivity values were found to range from 1 to 3 Ωm. A similar trend in the resistivity values was found with distance/depth for Bayer liquor contamination as observed with other leachates. Therefore, the installation of this innovative detection system below the liners in the aluminium industry can enable the effective monitoring of the lining systems and in case of failures, to take timely action for hazard mitigation.
Finally, based on the leak detection test results, empirical correlations and analytical modelling have been developed and presented for the relationship between resistivity, leakage duration and distance/depth. These can be used to predict the velocity of flow of leachate at any point within a liner base soil specimen. A numerical model for the seepage analysis of the leak detection test has been developed using the SEEP/W software. The flow velocity obtained from this model has then been used in conjunction with the new correlations to generate resistivity profiles for any specific soil type and leachate, in the leak detection test. Any other suitable seepage analysis software (e.g. GGU-SEEP, GGU-SS-FLOW2D, GGU-SSFLOW3D, etc.) can be used by practicing engineers to predict resistivity, and therefore, to design a suitable lining system for waste containment facilities.
This research work is particularly useful in generating awareness about the state of landfilling and will help various environmental protection agencies in making informed decisions for the development of rules and regulations to govern landfills. It is demonstrated that this system can be used to effectively detect and locate the liner leaks by simulating the field condition. The newly developed innovative diagnostic technique can be useful in designing the monitoring systems for waste storage and handling facilities, subbase contamination detection, liner leak detection, development and placement of sensors, soil and corrosion studies and so on, in Australia as well as worldwide.
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Jackson, Stephen Philip. "Cloning and characterisation of the RNA8 gene of Saccharomyces cerevisiae." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/15100.
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Forsström, Dan. "Novel techniques for characterisation of the oxidative stability of polyamides." Doctoral thesis, KTH, Polymer Technology, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2823.
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Forsström, Dan. "Novel techniques for characterisation of the oxidative stability of polyamides /." Stockholm : Tekniska högsk, 1999. http://www.lib.kth.se/abs99/fors0611.pdf.
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Ponnampalam, Dino R. "The development of analytical techniques for the characterisation of nanotubes." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493114.
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A linear aerosol time-of-flight mass spectrometer has been built to analyse carbon nanotubes. An aerodynamic lens system allows an aerosol-particle beam of controlled dimension and divergence to be formed.
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Menzies, Alan Robert. "Characterisation of gum arabic using physical, chemical and immunochemical techniques." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357114.
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Macey, Shaun Richard. "Optical fibre characterisation with particular reference to computer modelling techniques." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305620.
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Grydaki, Nikoletta. "Microbial characterisation of bioaerosols from indoor environments using molecular techniques." Thesis, University of Essex, 2017. http://repository.essex.ac.uk/23077/.
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Nowadays, the quality of air in the indoor environment is of increasing concern as it is estimated that the majority of people in developed countries spend about 85% of their time in various indoor micro-environments. The biological fraction of airborne particulate matter has become of increasing interest owing to the potential allergenic and pathogenic nature of airborne micro-organisms. Biological aerosols are ubiquitous and abundant in the air we breathe in the built environment and despite the recognition of the importance of bioaerosol exposure on human health, relatively little is known about the microbial agents in indoor air and there are still critical gaps in our understanding of the airborne microbial communities. Molecular biology methods demonstrate a great potential for improving our comprehension of the significance of the indoor aerosol microbial load in the context of human exposure, providing in-depth characterisation of microbial communities. However, the number of bioaerosol studies which have applied culture-independent techniques is still limited and the data on the airborne microbial particles in indoor environments remain scant and need to be further examined. The aim of the present study is to investigate the microbial abundance and diversity of bioaerosols in various different types of indoor environments using molecular techniques. Several research questions are being addressed by application of high throughput next generation sequencing technology, providing insights into the aerosol microbiome in micro-environments where people spend considerable amount of their time on a daily basis, including educational, residential and transportation settings. The results of this project provide novel information on a previously largely unexplored microbiome which could improve and expand our comprehension of the specific characteristics of bioaerosols in the indoor environment. Moreover, the data generated by this study could make a significant contribution to improving air quality by facilitating the development of methods for bioaerosol exposure monitoring.
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Klimczyk, Piotr. "Novel techniques for characterisation and control of magnetostriction in G.O.S.S." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/44515/.
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The magnetostriction of the core laminations is one of the primary causes of transformer acoustic noise. The magnetostriction of grain oriented silicon steel is extremely sensitive to compressive stress applied along its rolling direction which increases the magnitude of magnetostriction drastically. A measurement system using piezoelectric accelerometers has been built and optimised for magnetostriction measurements under stress within the range of 10 MPa to -10 MPa. This system was used for characterisation of wide range of samples which were prepared and processed under different thermal and mechanical conditions. In this study the influence of factors such as strip thickness, coating stress, annealing under tension, cutting stress and rotational magnetisation on the magnetostriction of silicon steel under stress were investigated. It was observed that the increase of strip thickness leads to the decrease of the magnetostatic energy and therefore a reduction in the volume of closure domains in the stress patterns leading to magnetostriction under stress increasing in proportion with the thickness. Also a gradual increase in coating weight resulted in an effective increase of tensile stress introduced to the surface of the steel which was evaluated by analysis of the stress shift of the magnetostriction curve. An investigation of sample cutting techniques showed that the water jet cutting introduced an advantageous tensile stress along the cut edge in the RD of the steel. Measurement of the pk-pk magnetostriction under rotational magnetisation was shown to be significantly higher than due to uniaxial magnetisation under high compression. The acquired data was used to develop a new prediction model based on the Boltzmann function capable of evaluating the influence of those factors on magnetostriction in GO steel. The final model was able to accurately describe the effect of all studied aspects being present during the production of the steel and affecting the magnetostriction sensitivity of the final material.
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Rodrigues, Paula Alexandra Pinto. "Archaeological roman glasses: comparative characterisation by non-destructive analytical techniques." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6145.
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Meor, Zulkifli Meor Mohd Faisal. "Characterisation of oxy-fuel flames using laser based diagnostics techniques." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45360.
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Oxygen enhanced oxy-fuel laminar and turbulent flame structure in a co-flow non-premixed jet burner are investigated. The measurement of intermediate species such as hydroxyl (OH) and formaldehyde (CH2O) and temperature are the focus of this work. The species concentrations were measured using planar laser induced fluorescence (PLIF) and the temperature using Rayleigh scattering. ‘Traditional Rayleigh’ requires a constant Rayleigh cross-section throughout the combustion process. This is impossible in high temperature oxy-fuel flames due to thermal decomposition. Derived temperature from Rayleigh signals is hence prone to inaccuracy. A direct comparison of measured and numerically-calculated Rayleigh signals can eliminate this error. Numerical Rayleigh signals are relatively easily calculated with knowledge of temperature and species concentration. The feasibility of adopting this procedure to validate the numerical model was investigated in laminar and turbulent flames. Sensitivity studies including radiation models, chemical kinetics mechanisms and the Soret effect were performed in laminar flames. Another Rayleigh technique, polarised/ depolarised Rayleigh was employed in a joint temperature, OH and CH2O measurement. The effect of varying O2 and jet Reynolds number on the flame structure was investigated. The applicability of determining heat release rate (HRR) using the product of [OH]x[CH2O] was also determined. [OH]x[CH2O] and HRR showed good spatial correlation in the main oxidation zone, but underestimated HRR in the secondary oxidation zone. Finally, analysis of thermal diffusion structures using high resolution polarised/ depolarised Rayleigh was performed. The analysis revealed the thickness of the diffusion layer is proportional to the temperature, axial location and O2 concentration. Increase of Reynolds number, however, reduces layer thickness. In summary, this work has used a suite of optical diagnostics to make the first structural survey of high temperature oxy-fuel flames, starting with overall flame shape through macroscopic localised extinction to microscopic thermal diffusion.
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Banfield, Beulah. "Human serum albumin characterisation and binding studies by spectroscopic techniques." Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/human-serum-albumin-characterisation-and-binding-studies-by-spectroscopic-techniques(1cae0d90-d540-46c9-8169-3b8ab2249acb).html.
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Human Serum Albumin (HSA) is a plasma protein of great significance with an ability to bind numerous endogenous and exogenous ligands, having a single polypeptide chain of 585 amino acids constructed in three domains of relatively equal size. Although HSA's existence has been known for many years, its characterisation and ability to bind ligands still remain enigmatic. Only in 1992 was the crystal structure of HSA reported (Carter and Ho, 1992). Effective crystallisation and the determination of meaningful crystallographic data and structure had proven difficult. The 1992 report concerned HSA crystals grown using zero gravity conditions. The objective of this project is the characterisation of recombinant and native HSA using Ultraviolet (UV) & circular dichroism spectroscopy (CD) and involved HSA conformational changes, which altered the ability to bind or off-load ligands. Changing environment, together with the use of characteristic "marker ligands," influences binding to provide a handle that can be utilised and monitored. This enables the assignment of binding sites and the study of perturbating conditions. Changing conditions such as pH, temperature, ionic strength and solvents in the presence and absence of ligands were employed to extract further information on this elusive protein. Fragments of recombinant HSA were also used (namely domain I and domain I + II) under identical conditions as the whole protein in order to help elucidate and assign binding sites.
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McDermott, Emma. "Characterisation of the osteoclast ruffled border using advanced imaging techniques." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236980.
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The osteoclast ruffled border is a highly convoluted, complex membrane that is necessary for bone resorption. It is thought to form following mass lysosomal fusion with the boneapposing plasma membrane and vesicular trafficking is vital for its formation and function. The aim of this PhD was to better understand the ultrastructure, formation and function of the ruffled border using TEM and advanced imaging techniques. Ruffled border reformation following calcitonin treatment was visualised and the stages of ruffled border formation were described. Ruffled borders in healthy and osteopetrotic osteoclasts were also imaged by TEM and characterised using a morphological grading system. The key findings of this thesis are as follows: (1) vacuoles, not lysosomes, are the primary contributors of membrane to the ruffled border and the membrane projections of the ruffled border form passively as a consequence of channel formation, not actively by membrane folding, (2) extracellular vesicles are located, and appear to be released, at the ruffled border. Various functional aspects of the ruffled border were also investigated. Vesicles near the ruffled border were identified and characterised by immunoelectron microscopy based on their content and morphology. We found no morphological defects in ruffled borders in mice deficient in Plekhm1. In osteoclasts derived from patients with a SNX10 mutation, we found that while the cells retained the capacity to form well-developed ruffled borders, they did so less often than healthy control osteoclasts. Importantly, we observed that even in a population of healthy osteoclasts, ruffled border morphology is highly heterogeneous because they are at different stages in the resorption cycle. In conclusion, the data in this thesis provide novel findings, previously unseen details regarding how resorbing osteoclasts interact with the bone surface, and have revealed unique insights into ruffled border morphology, formation and the vesicles with which it interacts.
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Du, Liangfen. "Characterisation of air-borne sound sources using surface coupling techniques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI028/document.
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La thèse se base sur la recherche des possibilités de caractérisation du son aérien de sources sonores arbitraires. A cette fin, une approche particulière est étudiée à l’endroit où la caractérisation de la source est faite via une surface d’interface qui enveloppe totalement ou partiellement la source physique. Deux descripteurs qui dépendent de la fréquence sont definis au travers d’une telle surface: la pression sonore bloquée et l’impédance de la source. Le précédent représente la pression sonore créée par le système d’exploitation source qui agit sur la surface enveloppante quand elle est rendue immobile. Cette dernière représente le rapport des amplitudes de réponse de pression et les amplitudes de vitesse d’excitation normales au travers de la surface. La surface enveloppante définit un volume d’air qui contient la source physique appelée l’espace source. Les deux descripteurs définis sur l’espace source, la pression bloquée et l’impédance de la source sont montrés comme étant intrinsèques à la source, c’est-à-dire indépendants de l’espace acoustique environnant. Une fois définis, ces descripteurs permettent de trouver la pression sonore et la vitesse particulaire normale à la surface de l’interface quand l’espace source est couplé à un espace récepteur arbitraire, c’est-à-dire une pièce. Cela permet alors la prédiction du son dans l’espace récepteur. Les conditions de couplage nécessitent que l’espace récepteur soit caractérisé en utilisant la même surface enveloppante telle que l’espace source. En acceptant de garder à l’esprit la simplicité de la mesure, la surface enveloppante a été conçue vu qu’elle comporte une ou plusieurs surfaces rectangulaires planes. Le défi de la recherche était alors d’obtenir une impédance significative de la surface au travers de la surface plane rectangulaire (continue) ainsi que celle de la pression bloquée compatible avec la formulation de l’impédance. Cela a conduit à une décomposition dans l’espace de la pression sonore et de la vitesse des particules au sein du nombre fini des composants, chacun défini par une amplitude complexe et une distribution dans l’espace particulière. De cette façon, la pression bloquée se réduit à un vecteur d’amplitude de pression complexe, tandis que l’impédance devient une matrice de pression et des rapports d’amplitudes complexes de la vitesse de défauts de de décompositions ont été recherchés dans le détail: la méthode harmonique de surface et la méthode du patch. Le premier se rapproche de la pression de surface et de la vitesse normale par des combinaisons de fonctions de surface trigonométriques en 2D tandis que ce dernier partage la surface en petites parcelles et intervient sur chaque parcelle de façon discrète en utilisant les valeurs moyennes du patchThe thesis investigates possibilities of air-borne sound characterisation of arbitrary sound sources. To this end a particular approach is studied where the source characterisation is done via an interface surface which fully or partially envelopes the physical source. Two frequency dependent descriptors are defined across such a surface: the blocked sound pressure and the source impedance. The former represents the sound pressure created by the operating source which acts on the enveloping surface when this is made immobile. The latter represents the ratio of pressure response amplitudes and normal velocity excitation amplitudes across the surface. The enveloping surface defines an air volume containing the physical source, called the source space. The two source descriptors defined on the source space, the blocked pressure and the source impedance, are shown to be intrinsic to the source, i.e. independent of the surrounding acoustical space. Once defined, these descriptors allow one to find the sound pressure and normal particle velocity at the interface surface when the source space is coupled to an arbitrary receiver space, i.e. a room. This in turn allows for sound prediction in the receiver space. The coupling conditions require that the receiver space is characterised using the same enveloping surface as the source space. Bearing the measurement simplicity in mind, the enveloping surface has been conceived as consisting of one or several rectangular plane surfaces. The research challenge was then to obtain meaningful surface impedance across a (continuous) rectangular plane surface as well as the blocked pressure compatible with impedance formulation. This has led to a spatial decomposition of sound pressure and particle velocity into finite number of components, each defined by a complex amplitude and a particular spatial distribution. In this way the blocked pressure reduces to a vector of complex pressure amplitudes while the impedance becomes a matrix of pressure and velocity complex amplitude ratios. Two decomposition methods have been investigated in detail: the surface harmonic method and the patch method. The former approximates the surface pressure and normal velocity by combinations of 2D trigonometric surface functions while the latter splits the surface into small patches and treats each patch in a discrete way, using patch-averaged values
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Muñoz, Arancón Alberto. "New techniques for the characterisation of single reeds in playing conditions." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1031/document.
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Ce travail porte sur la caractérisation d'anches simples utilisées pour la clarinette ou le saxophone. Sachant que les musiciens perçoivent des différences importantes dans la qualité des anches de caractéristiques identiques (même marque, coupe et force), cette thèse propose des nouveaux outils pour la caractérisation des anches en situation de jeu.Un bec instrumenté utilisant des capteurs embarqués est développé de façon à mesurer le déplacement de l'anche et la différence de pression de part et d’autre de l'anche. À partir de ces signaux, il est possible d'estimer des paramètres d'anche associés à différents modèles physiques. Les résultats obtenus montrent que la complexité du modèle décrivant le comportement de l'anche doit augmenter avec la nuance de jeu. Le bec instrumenté est utilisé dans une campagne de mesures comportant 7 musiciens et 20 anches, et permet de quantifier la variabilité des résultats due aux musiciens. Des tests subjectifs sont réalisés avec ces mêmes musiciens, et montrent que les différences entre les anches se réduisent à une seule dimension (facilité de jeu ou timbre). Les corrélations entre les descripteurs subjectifs et les paramètres objectifs mesurés sont étudiées afin de mieux comprendre les différences perçues entre les anches, permettant le développement d'un modèle prédictif de la qualité des anches.De façon à éviter la variabilité produite par le musicien, une bouche artificielle aspirante est développée. La comparaison des mesures réalisées par la bouche artificielle et par un musicien permet d'identifier la plage de fonctionnement optimale où la bouche artificielle imite au mieux le jeu du musicienThis work deals with the characterisation of single cane reeds used for clarinet or saxophone. Musicians perceive important differences of quality between reeds of the same brand, cut and strength. This thesis proposes new tools for reed characterisation in playing conditions.An instrumented mouthpiece is developed to enable the measurement of reed displacement and pressure difference on both sides of the reed using embedded sensors. From these signals, it is possible to estimate reed parameters of different physical models. Results reveal that the complexity of the physical model describing the reed behaviour must increase with the dynamic level.The instrumented mouthpiece is used in a measurement campaign involving 7 players and 20 reeds, quantifying the variability of the results due the musicians. Subjective tests conducted with these musicians show that reeds can be mainly described by one dimension (ease of playing or timbre). The correlations between the subjective descriptors and the measured objective parameters are studied to better understand the perceived differences between reeds, developing a predictive model of reed quality.In order to avoid the variability of the musician, an aspirating artificial mouth is developed. It uses the instrumented mouthpiece and it can be played by a musician or artificially. The comparison of the measurements made in both cases allows for the identification of the optimal working range in which the artificial mouth best reproduces the musician's playing according to intonation and playing level
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Scaife, S. J. "The characterisation of porous carbons using computer modelling and experimental techniques." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310862.
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Ireland, Terry G. "Precipitation techniques and characterisation of rare earth element doped phosphor materials." Thesis, University of Greenwich, 2008. http://gala.gre.ac.uk/6195/.
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The work in this thesis had two main aims. The first aim was to study the use of a number of precipitation methods to control the size and morphology of precursor phosphor materials for potential applications in a new generation of high definition and field emission displays. The morphological and luminescent characteristics of these precursor phosphor materials were studied after they were annealed to form their respective luminescent oxides using electron microscopy and light measuring techniques. The first set of experiments presented describes the development of a range of spherical submicron europium-doped yttrium oxide phosphor particles and their optimisation for use in the aforementioned applications. A homogeneous precipitation technique exploiting a hydrothermal decomposition of urea that provides hydroxycarbonate phosphor precursor ligands is at the centre of this work. In the presence of rare earth element nitrates the hydroxycarbonate ligands form spherical phosphor precursor particles that after annealing yield the luminescent oxides. This is followed by the presentation of a novel synthetic method using a micellar phase of rare earth element chlorides, after annealing, yielding europium-doped yttrium oxide. This method produces a variety of morphologies with crystallites as small as a few nanometres and up to hundreds of nanometres. Next is described a new precipitation method using ammonia and carbon dioxide gases that are introduced in a controlled manner into a solution of rare earth element chlorides at room temperature. Rare earth element hydroxycarbonates rapidly precipitate upon supersaturation, yielding a range of morphologies and particles sizes. The second aim of the thesis was to prepare a novel range of three-dimensional photonic band gap materials composed of conventional phosphor materials.
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Witting, Tobias. "New techniques for the characterisation of femto- and attosecond light pulses." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542994.
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Menachery, Anoop. "Devices and techniques for the dielectrophoretic characterisation and manipulation of cells." Thesis, Bangor University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502746.
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Gualandi, Adriano <1987>. "Spatial and temporal characterisation of ground deformation recorded by geodetic techniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7093/.
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A critical point in the analysis of ground displacements time series is the development of data driven methods that allow the different sources that generate the observed displacements to be discerned and characterised. A widely used multivariate statistical technique is the Principal Component Analysis (PCA), which allows reducing the dimensionality of the data space maintaining most of the variance of the dataset explained. Anyway, PCA does not perform well in finding the solution to the so-called Blind Source Separation (BSS) problem, i.e. in recovering and separating the original sources that generated the observed data. This is mainly due to the assumptions on which PCA relies: it looks for a new Euclidean space where the projected data are uncorrelated. The Independent Component Analysis (ICA) is a popular technique adopted to approach this problem. However, the independence condition is not easy to impose, and it is often necessary to introduce some approximations. To work around this problem, I use a variational bayesian ICA (vbICA) method, which models the probability density function (pdf) of each source signal using a mix of Gaussian distributions. This technique allows for more flexibility in the description of the pdf of the sources, giving a more reliable estimate of them. Here I present the application of the vbICA technique to GPS position time series. First, I use vbICA on synthetic data that simulate a seismic cycle (interseismic + coseismic + postseismic + seasonal + noise) and a volcanic source, and I study the ability of the algorithm to recover the original (known) sources of deformation. Secondly, I apply vbICA to different tectonically active scenarios, such as the 2009 L'Aquila (central Italy) earthquake, the 2012 Emilia (northern Italy) seismic sequence, and the 2006 Guerrero (Mexico) Slow Slip Event (SSE).
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Hussein, Salah A.-R. Ahmed. "Characterisation of planar defects in solids using ultrasonic pulse echo techniques." Thesis, City University London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389705.
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Cafferty, Stephen. "Characterisation of automotive shock absorbers using time and frequency domain techniques." Thesis, University of Manchester, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538689.
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Peacock, Joanne. "The surface characterisation of pharmaceutical mini-tablets using thermal probe techniques." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/51330/.
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This thesis assesses the ability of a range of novel thermo-analytical techniques to determine the spatial distribution of components across the surface of pharmaceutical mini-tablets. Such information is of use in formulation development, as the surface is the point at which a solid dosage form comes into contact with the environment, and where drug stability and excipient functionality are critical. Mini-tablets provide a good model system for surface characterisation, as they have much higher surface area to volume ratios than conventionally sized tablets. Five excipients and two drugs, as powders and after compaction, were individually characterised by the following techniques: scanning electron microscopy (SEM), variable temperature infrared spectroscopy (VT-IR), differential scanning calorimetry (DSC), atomic force microscopy (AFM), micro-thermal analysis (micro-TA), nano-thermal analysis (nano-TA) and transition temperature microscopy (TTM). Compacts of mixed systems were tested using AFM, micro-TA, nano-TA and TTM, building up the complexity to 4-component systems for excipient-only mixtures and 5-component systems for drug-loaded mixtures. Micro-TA, nano-TA and TTM were able to detect each component in all of the multi-component compacts, but AFM could not differentiate between them in complex systems. The study was then repeated on realistic mini-tablet formulations, confirming these initial results. Additionally, Raman microspectroscopy was performed on the mini-tablets as a corroborative technique, this method being based on a different physical phenomenon. In conclusion, the thermal probe techniques (micro-TA, nano-TA and TTM) were shown to be sufficiently discriminating to allow the spatial mapping of components across the surface of realistic mini-tablet formulations. Hence, these techniques could be used alongside spectroscopic techniques in the analysis of complex surfaces. However, some serious issues with the automated analysis and data display functions in the TTM software were identified, which could lead to misinterpretation of the results. Potential corrective measures were suggested to alleviate these concerns and improve experimental reliability.
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Lowis, Christopher R. "In-duct measurement techniques for the characterisation of broadband aeroengine noise." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/52074/.
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The focus of this thesis is the measurement of broadband fan noise, which due to reductions in tonal and jet noise, is now the dominant source at approach, and a major contributor at takeo. This thesis proposes three new in-duct measurement techniques for the characterisation and measurement of broadband fan noise. A complete characterisation of broadband noise involves determining the sources of sound, their location, and the sound eld they generate. The rst new in-duct measurement technique uses inverse methods to determine the noise source strengths on a ducted fan. The novel aspect of this technique is that it allows source strengths to be determined both in the rotating (or rotor-bound) reference frame and stationary (stator-bound) reference frame. The second technique is the development of an in-duct, rotating focus beamformer that allows beamforming in both rotating and stationary reference frames using an in-duct microphone array. The ability of the beamformer to determine the strengths of the rotor-based and stator-based sources is demonstrated using numerical simulations, with particular emphasis on the determination of the relative contributions of the rotor and the stator to overall broadband noise. The third measurement technique is designed to allow radiated directivity patterns to be predicted from in-duct measurements. This technique allows the prediction of radiated directivity from hollow no-ow ducts, fan inlets and annular exhaust ducts from in-duct measurements. The technique is also validated using experimental data acquired from a no-ow duct rig. Finally, an in-situ phase calibration method for in-duct axial arrays is proposed. This technique allows the rapid calibration of microphone arrays used in the three measurement techniques presented in the thesis. The technique is validated using experimental data.
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Hultén, Leo, and Philip Jansson. "Investigation and Evaluation of Metal Powder Characterization Techniques : Currently available at the KTH Department of Material Science and Engineering." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231469.
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The KTH Department of Materials Science and Engineering has lacked powder metallurgy research for many years, and as this field is constantly gaining in importance, such research needs to be reestablished. This requires the department to be able to accurately and efficiently characterize the properties of a powder, such as size distribution and composition, and in the short term, this needs to be done using non-specialized equipment. This project aimed to assess the availability and usefulness of both traditional and novel characterization methods by way of trial characterization experiments as well as a literature review. The experiments resulted in some data about three sample powders, as well as the conclusions that size distribution could be effectively characterized by automatized image analysis, composition could be characterized using Energy Dispersive X-ray Spectroscopy and that sample preparation was key to good results. It was concluded that the department could conceivably evaluate the most important properties, but that sampling and sample preparation routines need to be established to ensure efficient characterization and representative data.Materialinstitutionen på Kungliga Tekniska högskolan har i många år helt saknat pulvermetallurgiforskning och eftersom detta fält ständigt blir mer relevant behöver denna forskning återetableras. Detta kräver att institutionen med tillräcklig noggrannhet och effektivitet kan bestämma egenskaper hos ett pulver, såsom storleksfördelning och sammansättning, och på kort sikt behöver detta ske med ickespecialiserad utrustning. I detta projekt har tillgänglighet och användbarhet hos både traditionella och innovativa analysmetoder utvärderats med hjälp av experimentell karaktärisering av pulver samt en litteraturstudie. Experimenten gav data om de tre undersökta pulvren och resulterade även i slutsatsen att storleksfördelning kunde bestämmas med automatiserad bildanalys, att samansättning kunde bestämmas med Energi Dispersiv Röntgen Spektroskopi och att provpreparering äravgörande för bra resultat. Av detta följer att institutionen rimligtvis kan bestämma de viktigaste egenskaperna hos ett pulver, men att rutiner för provtagning och provpreparering behöver etableras för att säkerställa effektiv analys och representativ data.
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Chadha, Marcus J. "Novel techniques for the characterisation of exopolysaccharides secreted by lactic acid bacteria." Thesis, University of Huddersfield, 2009. http://eprints.hud.ac.uk/id/eprint/8749/.
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This project investigated the structures and physical characteristics of exopolysaccharides (EPSs) secreted by lactic acid bacteria. The structure of a novel exopolysaccharide (EPS) produced by Lactobacillus acidophilus 5e2 has been characterised. Analysis of the anomeric region of the H-NMR showed that the repeating oligosaccharide contained seven monosaccharides. GC-MS showed the structure to consist of D-glucose, D-galactose and D-N-acetyl-glucosamine in a molar ratio of 3:3:1. The linkage analysis showed that there were two terminal, three di-linked and two tri-linked monosaccharides, and in collaboration with data generated from a series of D-NMR experiments, an overall structure was determined. The weight-average molecular weight (Mw) of the EPS secreted by Lactobacillus acidophilus 5e2 when grown in skimmed milk was monitored during extended fermentation times. During the exponential growth phase, the increase in Mw closely followed the increase in yield of EPS. Under the fermentation conditions applied in this study, few if any new polysaccharide chains were formed during this growth phase despite a twenty five-fold increase in the cell count; almost the entire increase in yield can be accounted for by an increase in chain length. These results suggested that synthesis of new EPS chains is switched off during the exponential and stationary phase of fermentation. The increase in yield observed in this period is a consequence of the bacteria's ability to extend existing chains right up to the mid-stationary phase. These results raise questions about the factors that control EPS production and chain length. Depolymerisation techniques have been shown to reduce the Mw of the polysaccharide in a controlled manner. The H-NMR results have shown that the physical methods, constant pressure and ultrasonic disruption break the EPS randomly through the repeating oligosaccharide unit; polydispersity data suggests that the breakages were occurring midchain. A change to the peaks in the anomeric region of the H-NMR spectrum showed that depolymerisation, by acid hydrolysis, was chemically modifying the EPS structure. The approximate intrinsic viscosities of the EPS produced by Lactobacillus acidophilus 5e2 were determined to range between 0.6–2.0 dL g-1 for the Mw range of 1.59x105 – 4.78x105 g mol-1. A capillary zone electrophoresis method was developed to determine the monosaccharide composition of two EPS samples. The method successfully determined D-glucose and Dgalactose, but a peak for D-N-acetyl-glucosamine was not seen. The method was sensitive compared to current techniques, but not as low as using a HP-AEC-PAD. A novel method using LC-MS was developed for the linkage analysis of EPSs. Methylation, hydrolysis and reductive amination were used to derivatise the polysaccharide, and the fragmentation patterns were examined to determine the different linkage positions. Due to undesirable further fragmentation the method could not unequivocally differentiate between the different linkage positions, but the method was capable of resolving the monosaccharides residues with different linkage positions, at approximately the correct relative ratio.
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Dunin-Borkowski, Rafal Edward. "Fresnel and high resolution techniques for the characterisation of ultrathin semiconductor layers." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338135.
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