Tesi sul tema "Scanning"
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1
Svahn, Stefan. "3D-scanning : Volymberäkning vid scanning av bergvägg". Thesis, Karlstads universitet, Institutionen för geografi, medier och kommunikation, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-33349.
Testo completoAbstract (sommario):
Scanning är ett verktyg som har utvecklats mycket och används mer och mer inom geodetisk mätning. Instrumenten har blivit mer pålitliga med högre kvalité på resultaten, därför är det viktigt att eliminera de problem som kan skada scanningens pålitlighet. Det problemet som ska undersökas och testas i det här examensarbetet uppstår när man till exempel scannar en bergvägg. Man vill få en så lik avbildning av bergväggen som möjligt för att sedan kunna göra volymberäkningar emot bergväggen. Avbildningen av bergväggen består av ett moln av punkter som tillsammans skapar en 3D-modell av bergväggen. Om det ska fyllas med betong emot bergväggen så måste man veta vilken volym betong det kommer gå åt, därför är det viktigt att modellen av bergväggen stämmer. Problemet är att modellen kan visa sig att vara fel beroende på hur man har scannat. Det är när bergväggen är så pass ojämn och att man inte kan scanna från alla vinklar som det uppstår så kallade skuggor i modellen, en hålighet i berget kan då i modellen istället vara fylld. Detta gör att det går åt mer volym när man ska fylla igen vilket kan bli dyrt för alla inblandade. För att testa detta ska flera olika metoder testas under arbetet, olika typer av instrument, täthet mellan punkter, olika infallsvinklar och manuell scanning. Det som är intressant att se är hur pass mycket metoderna skiljer sig mellan varandra och genom att jämföra dessa så kan man få fram ett resultat som visar vilken metod som är mest trovärdig. Arbetets resultat och analys finns att läsa senare i den här rapporten där man också får svar hur arbetet genomfördes och hur metoderna skilde sig emot varnadra.
2
Raspin, P. "Scanning business environments : an investigation into managerial scanning behaviour". Thesis, Cranfield University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401662.
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3
Niblock, Trevor. "Micro scanning probes". Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395357.
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4
Leane, Robert B. "Scanning tunnelling microscopy". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291716.
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5
Hyde, Neville. "Environmental scanning : the need for and overview of environmental scanning system". Thesis, Stellenbosch : University of Stellenbosch, 2000. http://hdl.handle.net/10019.1/4595.
Testo completoAbstract (sommario):
Thesis (MBA (Business Management))--University of Stellenbosch, 2000.ENGLISH ABSTRACT: Historically organisations have had the "luxury" of being able to anticipate future developments and respond to them in good time due to, firstly, the comparatively slow pace of change and, secondly, the past being a relatively good predictor of the future. The second half of the 20th Century bears witness to some of the most dramatic changes and developments experienced by mankind. Most notable of these were globalisation, de-regulation, the emergence of the information/knowledge economy and, perhaps most significant of all, the changes brought about by the Internet. The underlying assertion of this report is that, given the current, complex, dynamic and sometimes volatile nature of changes in the external environment, in order to ensure a sustainable competitive advantage, organisations will be forced to consider carefully the dynamics of the environment in which they operate and to build their plans around these dynamics. This report briefly traces the evolution of strategic planning to its current status prior to providing a detailed analysis of the nature of environmental scanning and its applicability to strategic planning. The report provides a theoretical rerview of environmental scanning and a discussion of some of the tools and techniques of environmental scanning. Within this context the report provides a brief indication of the extent of the practice of environmental scanning within the financial services sector of South Africa. The conclusion assesses the findings of the current state of the practice of environmental scanning against the theory, with the view to providing an insight into the extent to which environmental scanning is applied in South Africa. Possible future directions of research and development of the practice are also identified.
AFRIKAANSE OPSOMMING: Histories gesproke, het instansies oor die "luukse" beskik om toekomstige ontwikkelinge vooruit te kon waarneem en betyds op hulle te reageer, eerstens weens die betreklike stadige pas van verandering en tweedens, omdat die verlede 'n betreklike goeie voorspeller van die toekoms was. Die tweede helfte van die 20ste eeu getuig van sommige van die mees dramatiese veranderinge en ontwikkelinge wat deur die mens ondervind is. Die mees uitstaande was globalisering, deregulering, die verskyning van die inligting/kennis-ekonomie en, dalk die mees uitstaande van almal, die veranderinge wat deur die Internet teweeggebring is. Die onderliggende stelling van hierdie verslag is dat, gegewe die huidige, komplekse, dinamiese en soms onbestendige aard van veranderinge in die eksterne omgewing, om 'n mededingende voordeel te verseker, sal instansies geforseer word om die dinamika van die omgewing waarin hulle werk, versigtig te oorweeg en om hulle planne om hierdie dinamika te bou. Hierdie verslag speur kortliks die ewolusie na van strategiese beplanning tot sy huidige status gevolg deur 'n omvattende analise van die aard van omgewingsondersoeke en die toepaslikheid daarvan op strategiese beplanning. Die verslag voorsien 'n teoretiese oorsig tot omgewingsondersoeke en 'n bespreking van sommige van die instrumente en tegnieke van omgewingsondersoeke. Binne hierdie konteks voorsien die verslag 'n kort aanduiding van die omvang van die uitvoering van omgewingsondersoeke binne die finansiele dienstesektor van Suid-Afrika. Die slot som die bevindings op van die huidige toestand van die praktyk van omgewingsondersoeke volgens die teorie, met die oog op voorsiening van 'n insig in die mate waartoe omgewingsondersoeke in Suid-Afrika toegepas word. Moontlike toekomstige rigtings van navorsing en ontwikkeling van die praktyk word ook geidentifiseer.
6
Hyde, Neville, e Johan Burger. "Environmental scanning : the need for and overview of environmental scanning systems". Thesis, Stellenbosch : University of Stellenbosch, 2000. http://hdl.handle.net/10019.1/4656.
Testo completoAbstract (sommario):
ENGLISH ABSTRACT: Historically organisations have had the "luxury" of being able to anticipate future developments and respond to them in good time due to, firstly, the comparatively slow pace of change and, secondly, the past being a relatively good predictor of the future. The second half of the 20th Century bears witness to some of the most dramatic changes and developments experienced by mankind. Most notable of these were globalisation,de-regulation, the emergence of the information/knowledge economy and, perhaps most significant of all, the changes brought about by the Internet. The underlying assertion of this report is that, given the current, complex, dynamic and sometimes volatile nature of changes in the external environment, in order to ensure a sustainable competitive advantage, organisations will be forced to consider carefully the dynamics of the environment in which they operate and to build their plans around these dynamics. This report briefly traces the evolution of strategic planning to its current status prior to providing a detailed analysis of the nature of environmental scanning and its applicability to strategic planning. The report provides a theoretical overview Qf environmental scanning and a discussion of some of the tools and techniques of environmental scanning. Within this context the report provides a brief indication of the extent of the practice of environmental scanning within the financial services sector of South Africa. The conclusion assesses the findings of the current state of the practice of environmental scanning against the theory, with the view to providing an insight into the extent to which environmental scanning is applied in South Africa Possible future directions of research and development of the practice are also identified.AFRIKAANSE OPSOMMING: Histories gesproke, het instansies oor die "luukse" beskik om toekomstige ontwikkelinge vooruit te kon waarneem en betyds op hulle te reageer, eerstens weens die betreklike stadige pas van verandering en tweedens, omdat die verlede 'n betreklike goeie voorspeller van die toekoms was. Die tweede helfte van die 20ste eeu getuig van sommige van die mees dramatiese veranderinge en ontwikkelinge wat deur die mens ondervind is. Die mees uitstaande was globalisering, deregulering, die verskyning van die inligting/kennis-ekonomie en, dalk die mees uitstaande van almal, die veranderinge wat deur die Internet teweeggebring is. Die onderliggende stelling van hierdie verslag is dat, gegewe die huidige, komplekse,dinamiese en soms onbestendige aard van veranderinge in die eksterne omgewing, om 'n mededingende voordeel te verseker, sal instansies geforseer word om die dinamika van die omgewing waarin hulle werk, versigtig te oorweeg en om hulle planne om hierdie dinamika te bou. Hierdie verslag speur kortliks die ewolusie na van strategiese beplanning tot sy huidige status gevolg deur 'n omvattende analise van die aard van omgewingsondersoeke en die toepaslikheid daarvan op strategiese beplanning. Die verslag voorsien 'n teoretiese oorsig tot omgewingsondersoeke en 'n bespreking van sommige van die instrurnente en tegnieke van omgewingsondersoeke. Binne hierdie konteks voorsien die verslag 'n kort aanduiding van die omvang van die uitvoering van omgewingsondersoeke binne die finansiele dienstesektor van Suid-Afrika. Die slot som die bevindings op van die huidige toestand van die praktyk van omgewingsondersoeke volgens die teorie, met die oog op voorsiening van 'n insig in die mate waartoe omgewingsondersoeke in Suid-Afrika toegepas word. Moontlike toekomstige rigtings van navorsing en ontwikkeling van die praktyk word ook geidentifiseer.
7
Weise, Thibaut. "Real-time 3D scanning". Konstanz Hartung-Gorre, 2009. http://d-nb.info/1000182894/04.
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8
Almqvist, Nils. "Scanning probe microscopy : Applications". Licentiate thesis, Luleå tekniska universitet, Materialvetenskap, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17980.
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9
Donnermeyer, Achim. "Scanning ion-conductance microscopy". [S.l.] : [s.n.], 2007. http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:de:hbz:361-11593.
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10
Davies, D. G. "Scanning electron acoustic microscopy". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304042.
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11
Møller, Christian Nicolai. "Scanning slit 3D displays". Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613824.
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12
Shen, Bing. "Multiple reflector scanning antennas". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40108.
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13
Descour, Michael Robert. "Non-scanning imaging spectrometry". Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186904.
Testo completoAbstract (sommario):
The objective of imaging spectrometry is to collect three-dimensional data about object space. Two of the three dimensions are spatial. The third dimension is spectral. Current techniques rely on some form of scanning, causing instruments to include moving components and/or to be capable of imaging only static or slowly changing scenes. An interpretation of the problem in terms of computed tomography leads to a system design which can fulfill the objective of imaging spectrometry without scanning. The imaging spectrometer assumes the frame-rate and integration-time properties of its imaging array. The raw data collected by such an instrument must be processed to yield temporally coincident spectral images of the scene. The computed tomography imaging spectrometer is therefore an example of indirect imaging. The three-dimensional frequency-space viewpoint and the associated central slice theorem form the theoretical basis for an understanding of this technique and its limitations. As described here, computed tomography imaging spectrometry belongs to the class of limited-view-angle problems. The spectrometer is treated as a discrete-to-discrete mapping and described accordingly by the linear imaging equation g = Hf + n. The M-element vector g represents the data collected by the spectrometer. The purpose of the instrument and the subsequent processing is the acquisition of the object cube f. In the discrete-to-discrete model, f is approximated as a vector of N independent elements. The vector n represents measurement-computing noise. The M-by-N matrix H embodies the imaging properties of the instrument. We have developed and implemented an experimental method of characterizing H. Such an approach yields a description of the imaging spectrometer which is more accurate than techniques that model the instrument and compute H. Inversion of the imaging equation to find an estimate of f has been best performed by the Expectation-Maximization algorithm. This approach is based on a Poisson likelihood law and therefore the assumption of quantum noise dominating the measurements g.
14
Harasaki, Akiko. "Improved vertical scanning interferometry". Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289148.
Testo completoAbstract (sommario):
Vertical scanning interferometers are routinely used for the measurement of optical fiber connectors. There are increasing needs for measurements of such items as machined surfaces, contact lenses, paint texture, cell structure, and integrated circuit devices, to name a few. These structures have too much depth, or are too rough, to measure with standard interferometry methods. Phase-measurement interferometry methods are limited to surfaces that do not have any discontinuities larger than one quarter of the operating wavelength. On the other hand, vertical scanning interferometers can be very effective, even though they have low height resolution compared to that of phase-measurement interferometers. Improving the height resolution of vertical scanning interferometers from the point of hardware improvement and signal processing has been one of the major research interests in the surface metrology area. This work provides a new algorithm, which called here "PSI on the Fly" technique, as a solution for improving height resolution of vertical scanning interferometers. This dissertation begins with a review of white-light interference microscopes. The height and lateral resolutions are derived based on scalar diffraction theory. Next, various well-established. algorithms for finding a topographic map of the small object surface are discussed. The work proceeds with a discussion of the phase change upon reflection and its influence on the coherence envelope. Then phase measurement interferometry methods are reviewed. The emphasis is in errors in phase measurement resulting from using a white light source instead of a monochromatic light source as in the usual case. The following chapter describes and examines an often-observed artifact of vertical-scanning interferometry when applied to step heights. The artifact is called "bat wings" because of its appearance. The physical cause of the "bat wings" artifact is discussed through a diffraction model. The next chapter proposes an improved vertical-scanning interferometry algorithm. The method, called here "PSI on the Fly" technique, has been developed by combining regular vertical-scanning interferometry and a monochromatic phase-shifting interferometry technique. The PSI on the Fly technique improves the surface height resolution of vertical scanning interferometry to that of a phase-shifting interferometry measurement. In addition to the resolution improvement, the algorithm also successfully removes the "bat wings" artifact.
15
Livadaru, Matilda Gabriela. "Low Cost Scanning Arrays". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3780.
Testo completoAbstract (sommario):
Over the past decades, phased arrays have played a significant role in the development of modern radar and communication systems. The availability of printed circuit technology and ease of integration with microwave components, as well as the development of low profile and low weight approaches, have also played an important role in their conformal adaptation. However, fabrication costs remain prohibitive for many emergent platforms, including 5G base stations and autonomous vehicles, when compared to a conventional mechanically steered passive array. Therefore, cost reductions in the fabrication and integration of modern phased arrays are essential to their adaptation for many upcoming commercial applications. Indeed, although phased array design methods are well-understood, even for wideband and wide-angle scanning applications, their fabrication is still based on high-cost, low-yield printed circuit technology. With this in mind, this dissertation focuses on a new planar aperture topology and low-cost techniques for phased array methodologies.
The first part of the thesis presents new fabrication advancements using commercially available multi-layered printed circuit technologies. We discuss methods for low cost fabrication while still maintaining performance and design constraints for planar array apertures. The second part of the dissertation presents a novel Integrated Planar Array (IPA) at S-Band and discusses dramatic cost reductions for multi-function radar applications. Performance and cost benefits are presented, and fabrication techniques to exploit an emerging class of high-speed digital laminates are discussed. These are compatible with high-volume, high-yield production, while reducing aperture cost by 75% when compared to conventional approaches.
Performance of a planar array employing a pin-fed dual-polarized antenna element with active VSWR
Overall, this dissertation addresses several manufacturing and performance challenges in realizing affordable planar phased arrays using low cost fabrication without performance compromise. As commercial interest in phased array technology is anticipated to grow, the proposed approaches for phased array design and fabrication will enable quick turnaround times for mainstream adoption.
16
Pan, Jingyi. "Confocal scanning laser tomography and scanning laser Doppler flowmetery in the rat eye". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ49422.pdf.
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17
Behan, Gavin Joseph. "Optical sectioning in the aberration-corrected scanning transmission and scanning confocal electron microscope". Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:10c7151c-ff1f-4f88-a783-9ad5cf4831ec.
Testo completoAbstract (sommario):
This thesis concerns the experimental application of the technique of optical sectioning in the aberration-corrected scanning transmission electron microscope (STEM). Another aim was to perform optical sectioning experiments on the still relatively new scanning confocal electron microscope (SCEM). To test the feasibility of this technique, experiments were performed on a variety of samples to measure the achievable depth response. Deconvolution methods were explored in an attempt to further improve the depth response. Finally, some of the first optical sectioning experiments were performed in the SCEM using both elastic and inelastically scattered electrons. The results showed a clear need to investigate confocal electron microscopy due to the missing cone problem for incoherent imaging in the STEM. This is particularly evident when imaging objects of greater width than the STEM probe. Confocal electron microscopy using inelastic electrons appeared to be a promising imaging mode for the future with this thesis consisting of early work in the field.
18
Rosolen, Grahame Craig. "The development of a combined scanning electron microscope and scanning tunnelling microscope for nanotechnology". Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241061.
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19
Persson, Angelica, e Amanda Lindewald. "Extraoral 3D-scanning - conformity between extraoral 3D scanning and clinical measurements of the face". Thesis, Malmö universitet, Odontologiska fakulteten (OD), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42624.
Testo completoAbstract (sommario):
Aim: To use the extraoral scanner 3D Sense in practice and compare the measurements on scanned material with conventional, direct clinical measurements. This is to evaluate if extraoral scanning can replace a clinical examination and extraoral 2D photography. Material & method: Fifteen adults at the Faculty of Odontology were recruited for the study. Five determined landmarks were marked in the faces of the subjects. Direct clinical measurements were performed between the landmarks of every subject and used as a reference. The subjects' faces were scanned and the same distances were measured in the scans. Differences in measurements of the two methods were conducted in a paired t-test. Intra- and inter operator differences were calculated for all distances. Intraclass correlations were used to describe to what extent subjects in the same group resemble each other. Results: Conformity of direct clinical measurements and measurements on scanned material varied between the mean difference of 0,22-5,13 mm. Intra- and inter operator ICC was overall excellent. Conclusion: The measurements between the landmarks pronasale (prn) and pogonion (pg) was the only distance with no statistical significant difference between the two methods. The 3D Sense shows decreasing conformity to clinical measurements with increasing distances. Inter operator ICC shows excellent values and measuring on scanned material can be regarded as a reproducible method. The results indicate clinical acceptance for use of 3D Sense for some purposes in odontology. 3D Sense has been validated in-vitro and analyzed in-vivo. The studies have established the 3D Sense’s adequacy in odontology.
20
Kulawik, Maria. "Low temperature scanning tunneling microscopy". Doctoral thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979718848.
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21
Lee, Su-Young. "Multi-channel scanning SQUID microscopy". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1490.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
22
Ding, Haifeng. "Spin-polarized scanning tunneling microscopy". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963217186.
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23
Djuričič, Dejana. "Biological scanning probe microscopy (SPM)". Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403609.
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24
Pinheiro, Lucidalva dos Santos. "Scanning probe microscopy of adsorbates". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320589.
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25
Eren, Gönen. "3D scanning of transparent objects". Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00584061.
Testo completoAbstract (sommario):
Many practical tasks in industry, such as automatic inspection or robot vision, often require scanning of three-dimensional shapes with non-contact techniques. However, transparent objects, such as those made of glass, still pose difficulties for classical scanning techniques. The reconstruction of surface geometry for transparent objects is complicated by the fact that light is transmitted through, refracted and in some cases reflected by the surface. Current approaches can only deal relatively well with sub-classes of objects. The algorithms are still very specific and not generally applicable. Furthermore, many techniques require considerable acquisition effort and careful calibration. This thesis proposes a new method of determining the surface shape of transparent objects. The method is based on local surface heating and thermal imaging. First, the surface of the object is heated with a laser source. A thermal image is acquired, and pixel coordinates of the heated point are calculated. Then, the 3D coordinates of the surface are computed using triangulation and the initial calibration of the system. The process is repeated by moving the transparent object to recover its surface shape. This method is called Scanning From Heating. Considering the laser beam as a point heating source and the surface of the object locally flat at the impact zone, the Scanning From Heating method is extended to obtain the surface normals of the object, in addition to the 3D world coordinates. A scanner prototype based on Scanning From Heating method has been developed during the thesis.
26
Davis, Robert Patrick. "Nanolithography using scanning tunnel microscopy". Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318840.
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27
Puygranier, B. A. F. "The photon scanning tunnelling microscope". Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368568.
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28
Page, Ashley M. "Multifunctional scanning ion conductance microscopy". Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/99668/.
Testo completoAbstract (sommario):
Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has historically been used for the topographical imaging of soft samples. This thesis demonstrates the development of SICM into a multifunctional tool, capable of providing a host of additional information about both biological and inert samples, whilst maintaining the structural mapping capability for which it is usually employed. Two approaches are taken to extend the functionality of SICM: (i) designing sophisticated potential, and positional, control functions that are then used with traditional single-channel nanopipettes; and (ii) incorporating an ion conductance channel into a multi-barrelled probe. In the single-channel setup, a pulsed-potential profile allows the extraction of surface charge density on extended substrates, and a ramped-potential profile permits spatially resolved mapping of redox reactions on an electrode substrate. When integrated into a more complex probe, SICM is used to study molecular uptake at cellular surfaces, and to print Cu microstructures on a Au substrate. While this thesis is primarily concerned with technique development, the studies herein have broad applications in cell biology, pharmaceuticals, materials science and beyond. In addition to developing imaging modes that allow the extraction of functional information at a surface, this thesis also contributes to the fundamental understanding of the SICM system. Finite element method simulations are performed alongside experimental studies, in order to fully understand the contributions of the pipette geometry, ion current rectification, and pipette-surface interactions on the measured ionic current. The theoretical treatment herein provides a foundation upon which future multifunctional SICM regimes could be designed, extending the scope of this increasingly powerful technique.
29
Venkatachalam, Vivek. "Simulating scanning tunneling microscope measurements". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36116.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (leaf 25).
One of the largest problems in scanning tunneling microscopy design is noise control. It is the burden of the designer to determine if money should be used to build a floating room for vibration isolation or for top-of-the-line preamplifiers that can be placed at low temperatures. This thesis presents a simulation of the STM measurement chain, from tunneling tip to computer control. The goal is to see how noise at different stages of the measurement chain affect the output of spectroscopy (density of states) measurements. Specifically, we look at how spectroscopy measurements depend on the temperature of the sample, the density of states in the sample and tip, the shakiness of the tip, the noise present in the current preamplifier, and several other settings. Chapter 1 describes STM spectroscopy measurement, Chapter 2 explains how it is simulated, and Chapter 3 finally looks at the results of various simulations.
by Vivek Venkatachalam.
S.B.
30
Mueller-Falcke, Clemens T. (Clemens Tobias). "Switchable stiffness scanning microscope probe". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32349.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 77-80).
Atomic Force Microscopy (AFM) has rapidly gained widespread utilization as an imaging device and micro/nano-manipulator during recent years. This thesis investigates the new concept of a dual stiffness scanning probe with respect to biological applications and determines the resulting requirements for the scanning of soft bio samples, such as low-pressure contact. On this basis, an in-plane AFM probe that is specifically tailored to the needs of biological applications is developed. It features a variable stiffness, which makes the stiffness of the probe adjustable to the surface hardness of the sample, and a very low overall stiffness, which is needed in order to achieve high resolution imaging. The switchable stiffness probe allows the scanning of biological samples with varying surface hardness without changing probes during scanning, and therefore prevents a loss of positional information, as is unavoidable with conventional devices. For the integration of the components into a MEMS device, the conventional cantilever-type design of AFM probes has been abandoned in favor of an in-plane design. The new design has an advantage in that it facilitates a high-density array of AFM probes and allows for easy surface micromachining of the integrated device. It also enables the future integration of micro-fluidic channels for reagent delivery and nanopipetting. For the scanning of nano-scale trenches and grooves, a multi-walled carbon nanotube, embedded in a nanopellet, is planned as a high-aspect-ratio tip. The variable stiffness is accomplished in a mechanical way by engaging or disengaging auxiliary beams to the compliant beam structure by means of electrostatically actuated clutches.
(cont.) For actuation, an electrostatic combdrive is considered to move the probe tip up and down. The vertical displacement of the tip can be measured by a capacitive sensor, which can easily be integrated into the system. A scaled-up proof-of-concept model is manufactured with surface-micromachining processes. The clutch performance is successfully tested and the dual stiffness concept is verified by measuring the stiffness of the device with the clutches engaged and disengaged.
by Clemens T. Mueller-Falcke.
S.M.
31
Chang, Jeremy T. "Fast scanning two-photon microscopy". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61148.
Testo completoAbstract (sommario):
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 45-46).
Fast scanning two-photon microscopy coupled with the use light activated ion channels provides the basis for fast imaging and stimulation in the characterization of in vivo neural networks. A two-photon microscope capable of fast scanning using acousto-optic deflectors was designed and implemented. The software controller was expanded so that random access scan in three dimensions could be handled, so that algorithms that can identify neurons from images acquired using the two-photon microscope can be developed. Finally the localization of optogenetic Channelrhodopsin-2 channel to the neuron cell body was tested using a ChR2-MBD construct.
by Jeremy T Chang.
M.Eng.
32
Xu, Ying. "A metrological scanning force microscope". Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/73129/.
Testo completoAbstract (sommario):
In last decade, there has been a tremendous progress in scanning probe microscopies, some of which have achieved atomic resolution. However, there still exist some problems which have to be solved before the instrument can be used as a metrological measurement tool. The object of the project introduced in this thesis was to develop a scanning force microscope of metrological capability with the aim of making significant improvement in scanning force microscopy from the viewpoint of instrumentation. A capacitance based force probe has been studied theoretically and experimentally with the main concern being its dynamic properties, characterized by squeeze air film damping, which are believed to have direct effects on the fidelity of measurement. The optimization of design is investigated so as to achieve the results of both high displacement sensitivity and force sensitivity. An x-y scanning stage has been designed and built, which consists of a two axis linear flexure system of motion amplifying mode machined from a single aluminium alloy block. The stage is driven by two piezo actuators with two capacitance sensors monitoring the actual position of the platform to form a closed loop control system. The design strategy is introduced and the performances and characteristics of two commonly used types of flexure translation mechanisms, leaf spring and notch hinge spring system, are analyzed. The finite element analysis method is employed in the analysis and design of translation mechanism. Finally, a metrological scanning force microscope has been constructed, combining a constant force probe system, an x-y scanning stage and a 3D coarse positioning mechanism into a metrological system. The performance of the instrument system has been systematically evaluated and its measuring capability investigated on the. specimens of various properties and features. The results from this first prototype of the instrument demonstrated a subnanometer resolution with comparable stability and repeatability in all three axes.
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Eves, Brian John. "Scanning probe energy loss spectroscopy". Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251871.
Testo completo
34
Gunér, Gustaf. "Receipt Scanning Using Deep Learning". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279697.
Testo completoAbstract (sommario):
Employees often make purchases on behalf of the companies that they are working for. These purchases must be reported manually, either by the employees themselves or by sending the receipts to the company‘s accountant. In both cases, parts of the receipts are transcribed manually. This process is time-consuming and poses a risk that the human factor causes transcription errors, which can lead to ambiguities in the company‘s financial statements. A fully-automatic receipt scanner, which from a photograph of a receipt can extract metadata (e.g. total price, VAT, and individual item names) would solve many of these problems. Not only would it make the reporting process more efficient, which would reduce costs and save time, but the correctness of the data could be increased too. In this report, the possibilities of using Deep Learning (DL) as an approach to receipt scanning are evaluated, in comparison to a heuristic Computer Vision (CV) solution. Both approaches detect the receipt in a photograph, preprocess the original photograph based on the location information and extract the text from it using Optical Character Recognition (OCR). The approaches were evaluated based on the accuracy of the predicted receipt locations and the accuracy of the extracted texts. The results show that the Deep Learning approach achieved significantly better results than the heuristic approach, in both tasks. In the generic test set, which combined all test instances, the Deep Learning approach achieved 31.1 percentage points higher average Intersection over Union (IoU), 23.4 percentage points lower average Character Error Rate (CER) and 17.5 percentage points lower average Word Error Rate (WER).Anställda på företag gör ofta utlägg för inköp. Dessa inköp måste rapporteras manuellt, antingen av varje enskild anställd eller genom att skicka kvittona till företagets revisor och låta denna person göra det. I båda fallen transkriberas delar av kvitton manuellt. Denna process är tidskrävande och utgör en risk för att den mänskliga faktorn orsakar fel i avskrivningen, vilket kan leda till tvetydigheter i företagets finansiella redovisningar. En helautomatisk kvittoscanner, som från ett foto av ett kvitto kan extrahera ut metadata (t.ex. totalpris, moms och individuella objektnamn) skulle lösa många av dessa problem. Utöver att lösningen skulle göra rapporteringsprocessen mer effektiv, vilket skulle mins- ka kostnader och spara tid, skulle även korrektheten i datan kunna förbättras. I denna rapport utvärderas möjligheterna att använda djupinlärning som metod för att scanna kvitton, i jämförelse med en heuristisk metod baserad på dator-seende. Båda metoderna detekterar kvittot i bilden, förbehandlar originalfotot baserat på kvittots platsinformation och extraherar sedan texten med hjälp av optisk teckenigenkänning. Metoderna utvärderades baserat på noggrannheten i de förutspådda platserna för kvittona och noggrannheten i de extraherade texterna. Resultaten visar att djupinlärningsmetoden uppnådde avsevärt bättre resultat än den heuristiska metoden, i båda avseendena. I den generiska testuppsättningen, som inkluderade samtliga testinstanser, uppnådde djupinlärningsmetoden 31.1 procentenheter högre genomsnittlig Intersection over Uni- on (IoU), 23.4 procentenheter lägre genomsnittlig Character Error Rate (CER) och 17.5 procentenheter lägre genomsnittlig Word Error Rate (WER).
35
Vo, Huy Nhu. "High-resolution Optical Scanning Holography". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/32527.
Testo completoAbstract (sommario):
Optical scanning holography, which was proposed by Poon[1], is a fascinating technology to record holographic information. The technique is applied in the operation of scanning holographic microscopy to record the entire three-dimensional volume of a biological specimen in the form of a hologram. With the data captured, a digital reconstruction or decoding is used to reconstruct the hologram of that such specimen. An accurate reconstruction of the recorded data provides with an in-depth analysis in the area where random noise and other imperfection effects may occur. In this thesis, three different approaches of reconstruction process are presented to provide in high-resolution a comparison between theoretical and experimental reconstruction a hologram of fluorescent beads. The first approach is to use only the experimental pinhole hologram recorded to correlate with the hologram of the object to give the reconstruction of the section. The second approach is to use the propagated pinhole hologram to reconstruct at an arbitrary depth. Finally, the third approach is to reconstruct without using the experimental pinhole hologram but with diffraction theory. Comparing these results in high-resolution gives us analysis of the reconstruction noise due to optical aberration.Master of Science
36
Sharples, Steve David. "All-optical scanning acoustic microscope". Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/10164/.
Testo completoAbstract (sommario):
In this thesis a new instrument, the all-optical scanning acoustic microscope (O-SAM) is presented, it is a non contact scanning acoustic microscope (SAM) which uses lasers to both generate and detect surface acoustics waves (SAWs) The non contact nature of the O-SAM overcomes some difficulties associated with conventional SAMs because of the couplant and surface contact involved. This O-SAM also overcomes many of the problems associated with conventional laser ultrasound systems including those of sample damage and ablation, low signal to noise ratio and slow data acquisition. Furthermore, the instrument is adaptive enabling it to compensate to acoustic aberrations that can occur as a result of material microstructure. We believe this is a most significant feature that will greatly enhance its range of applications. This thesis examines some of the key technological developments required to develop the O-SAM, including the use of tailored optical generation pattern realised through the use of a spatial light modulator (SLM) and the development of a novel high speed analogue data acquisition system. This thesis presents the design and construction of the instrument and demonstrates its imaging capability on engineering materials using SAWs at 82 and 164MHz although the instrument is potentially capable of imaging at much higher frequencies. Images are presented on ceramic, steel and aluminium samples which demonstrate a range of contrast mechanisms and measurement techniques, including the interaction of the material with Rayleigh waves and Lamb modes for the purpose of defect detection and characterisation, and measurement of local variations in residual surface stress, changes in coating thickness, and plate thickness.
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Neubeck, Soeren. "Scanning probe investigations on graphene". Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/scanning-probe-investigations-on-graphene(e0838733-8f13-4221-ad55-124e3757ba15).html.
Testo completoAbstract (sommario):
In this thesis, scanning probe microscopy experiments on graphene and chemically modified graphene crystals are discussed. Since its discovery in 2004, graphene has not only impressed researchers and industry because it is a crystal that is only one atom thick, butalso because of its electronic transport properties. However, a major challenge remaining is the task to introduce an energy gap in graphene. One way to open an energy gap in pristine graphene is its confinement to nanometre sizes. To this end, methods were developed to fabricate such nanostructures out of graphene. Here, the atomic force microscope (AFM) based technique of local anodic oxidation was applied to selectively oxidise graphene. Using this technique, graphene nanostructures as small as 20~nm have been fabricated. A graphene quantum dot (QD) created with this technique was measured at low temperatures. It showed quantum Coulomb blockade behaviour, with an energy gap of 10 meV. Furthermore, the transport behaviour of these nanostructures was also investigated under ambient conditions.Scanning gate microscopy measurements carried out on a graphene quantum point contact (QPC) demonstrated the possibility to locally influence the charge carrier concentration in the QPC, and thus alter the resistance of the device. These experiments additionally prove the usefulness of local anodic oxidation to create graphene nanostructures. Equally tempting as opening a gap in graphene and studying the resulting transport properties is the prospect of studying the influence of the edges terminating a graphene crystal on its transport properties. To that end, reliable methods for obtaining the crystallographic orientation of a given edge are needed. While most techniques require either elaborated sample fabrication or modelling, it is shown here how atomically resolved scanning tunnelling microscopy (STM) imaging together with Raman spectroscopy can be used to determine the crystallographic direction of graphene edges without doubt. An alternative way of creating an energy gap in graphene is its modification with atomic hydrogen. Atomic force microscopy was first used to measure the topography of hydrogenated graphene crystals. It is further shown, how the amount of adsorbed hydrogen could be decreased using AFM. The changes induced in the hydrogenated graphene samples in this way have been further corroborated by Raman spectroscopy and low temperature transport experiments, establishing AFM as a method to engineer the resistance of hydrogenated graphene.
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Svedberger, Johan, e Jonas Andersson. "Laser scanning in manufacturing industries : The potential and usability of laser scanning for industrial applications". Thesis, KTH, Industriell produktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134954.
Testo completoAbstract (sommario):
Making mistakes or discovering errors too late in the factory layout process is very costly. Unfortunately, the layouts aren’t always accurate or updated which creates a degree of uncertainty when it comes to installation of new equipment and rebuilding facilities. It also leads to a lot of waste in movement when employees has to go out in production to perform measurements, take pictures and take notes in order to remember important details to avoid errors. Lasers in land and engineering surveying instruments have been widely used for the last 30 years. A natural development has been to add a scanning mechanism to a total station that were already equipped with laser rangefinders and angular encoders, allowing automated measurement and location of thousands of nonspecific points. The automobile industry has begun to see the potential of laser scanning, mainly because of the development of the software handling the scan results, the point clouds. Scania, in collaboration with the FFI research project at the Royal Institute of Technology (KTH), therefore wanted to investigate how the new possibilities of 3D laser scanning can facilitate the development and maintenance of production systems and how it could be implemented in the current factory design process. By scanning three locations at Scania related to machining, assembly and aftermarket service the usability of the results has been investigated with the software Faro Scene and Bentley Pointools V8i. The results of the study showed that the laser scanning technology can generate several possibilities for manufacturing industries. The technology can be profitable and the modern point cloud software and applications could support the work of the layout design process greatly. Three main application areasfound: Visualization & communication: The point cloud is an excellent information carrier and can easily be used as a visualization aid for meetings or simply to refreshing memories of a location. It also provides the possibility to view and examine a location remotely. Gather information: The measuring possibilities are immense, allowing single point and distance measurements without the concern of interfering with objects. The method can to some extent replace the current approach in measuring buildings and floor flatness. Simulation & verification: Software can perform advanced simulations and verifications of existing and future layouts, models and installations. Parts of the point cloud can be colorized, hidden, removed, duplicated or transformed. Existing 2D layout drawings or 3D models can be attached and verified relative the point cloud. The attached objects can be simulated with clash collision or differencing. Keywords: 3D Laser Scanning, TLS, CAD, Point Cloud, Factory Layout, Faro Scene, Bentley Pointools V8i, FactoryDesign Process, Factory Scanning Process.
39
Wang, Lin. "Carrier profiling of ZnO nanowire structures by scanning capacitance microscopy and scanning spreading resistance microscopy". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI031/document.
Testo completoAbstract (sommario):
Ce travail de thèse porte sur l'application des techniques Scanning Capacitance Microscopy (SCM) et Scanning Spreading Resistance Microscopy (SSRM) pour la caractérisation électrique de nanofils de ZnO avec l'objectif d'en déterminer le dopage par profilage des porteurs libres suite à des essais de dopage de type p. Afin de pouvoir utiliser un référentiel planaire nécessaire à ces mesures par sonde locale, un procédé de remplissage par dip-coating et de polissage a été spécialement développé sur des champs de nanofils quasi-verticaux. De plus, dans le but de parvenir à un étalonnage des mesures SCM et SSRM, nous avons conçu et fait fabriquer des échantillons étalons de dopage de type n, contenant des niveaux de Ga en escalier de densité variable de 2×10^17 à 3×10^20 cm^-3. Les mesures sur des coupes transversales de ces deux de structures multicouches ont permis, pour la première fois sur ZnO d'établir un étalonnage des mesures SCM et SSRM et de déterminer le dopage intrinsèque électriquement actif de couches 2D nanométriques, résultat difficilement atteignable par d'autres techniques d'analyse. Des résultats inattendus de concentration résiduelle de porteur de l'ordre de 2×10^18 et 3×10^18 cm^-3 ont été trouvés sur les nanofils de ZnO crus par MOCVD et par CBD respectivement. Outre la caractérisation électrique microscopique des nanofils par SCM et SSRM, des techniques macroscopiques classiques ont été utilisées pour caractériser des assemblées importantes de nanofils de ZnO. L'origine de la difference entre les résultats de deux genres de technique a été discutée. Nous avons aussi étudié les effets des dopages ex-situ par diffusion du phosphore (procédé SOD) et des dopages in situ par incorporation d'antimoine (Sb) pendant la croissance MOCVD. Les résultats majeurs sont obtenus pour l'antimoine, en utilisant des couches ZnO: Sb 2D et des nanofils cœur-coquille ZnO/ZnO: Sb, ou l'hypothèse d'une compensation partielle du dopage n résiduel par un centre accepteur créé par le dopage Sb semble pouvoir être établie raisonnablementBased on atomic force microscope (AFM), scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) have demonstrated high efficiency for two dimensional (2D) electrical characterizations of Si semiconductors at nanoscale and then have been extensively employed in Si-based structures/devices before being extended to the study of some other semiconductor materials. However, ZnO, a representative of the third generation semiconductor material, being considered a promising candidate for future devices in many areas, especially in opto-electronic area, has rarely been addressed. Recently, extensive research interests have been attracted by ZnO NWs for future devices such as LED, UV laser and sensor. Therefore, a good understanding of electrical properties of the NWs is in need. In this context, this thesis work is dedicated to the 2D electrical characterization of ZnO NWs with the focus of carrier profiling on this kind of nanostructure in the effort of their p-type doping. For this purpose, a planarization process has been developed for the NWs structure in order to obtain an appropriate sample surface and perform SCM/SSRM measurements on the top of the NWs. For quantitative analysis, Ga doped ZnO multilayer staircase structures were developed serving as calibration samples. Finally, residual carrier concentrations inside the CBD and MOCVD grown ZnO NWs are determined to be around 3×10^18 cm^-3 and 2×10^18 cm^-3, respectively. The results from SCM/SSRM characterization have been compared with that from macroscopic C-V measurements on collective ZnO NWs and the differences are discussed. In addition to carrier profiling on NWs structure, applications of SCM/SSRM on some other ZnO-based nanostructures are also investigated including ZnO:Sb films, ZnO/ZnO:Sb core-shell NWs structure, ZnO/ZnMgO core-multishell coaxial heterostructures
40
Walton, John Moorcroft. "The acquisition, analysis and processing of Scanning Auger Microscopy (SAM) and Scanning Tunneling Microscopy (STM) data". Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387184.
Testo completo
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Martin, Geoffrey Clive. "Virtual Scanning Electron Microscope : a web-based teaching and training solution for the Scanning Electron Microscope". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611878.
Testo completo
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Strubhar, Andrew J. Hines Edward R. "Environmental scanning in physical therapy education". Normal, Ill. Illinois State University, 2000. http://wwwlib.umi.com/cr/ilstu/fullcit?p9995670.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Illinois State University, 2000.Title from title page screen, viewed May 2, 2006. Dissertation Committee: Edward R. Hines (chair), Patricia H. Klass, James C. Palmer, Mohamed Nur-Awaleh. Includes bibliographical references (leaves 133-145) and abstract. Also available in print.
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Moon, Jong Seok. "Next generation of multifunctional scanning probes". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42935.
Testo completoAbstract (sommario):
The goal of this thesis was the advanced design, fabrication, and application of
combined atomic force microscopy - scanning electrochemical microscopy (AFMSECM)
probes for high-resolution topographical and electrochemical imaging.
The first part of the thesis describes innovative approaches for the optimization of
AFM-SECM probe fabrication with recessed frame electrodes. For this purpose,
commercial silicon nitride AFM cantilevers were modified using optimized critical
fabrication processes including improved metallization for the deposition of the electrode
layer, and novel insulation strategies for ensuring localized electrochemical signals. As a
novel approach for the insulation of AFM-SECM probes, sandwiched layers of PECVD
SixNy and SiO2, and plasma-deposited PFE films were applied and tested. Using
sandwiched PECVD SixNy and SiO2 layers, AFM-SECM probes providing straight
(unbent) cantilevers along with excellent insulation characteristics facilitating the
functionality of the integrated electrode were reproducibly obtained. Alternatively, PFE
thin films were tested according to their utility for serving as a mechanically flexible
insulating layer for AFM-SECM probes. The electrochemical characterization of PFEinsulated
AFM-SECM probes revealed excellent insulating properties at an insulation
thickness of only approx. 400 nm. Finally, AFM-SECM cantilevers prepared via both
insulation strategies were successfully tested during AFM-SECM imaging experiments.
In the second part of this thesis, disk-shaped nanoelectrodes were for the first time
integrated into AFM probes for enabling high-resolution AFM-SECM measurements.
Disk electrodes with an electrode radius < 100 nm were realized, which provides a
significantly improved lateral resolution for SECM experiments performed in
synchronicity with AFM imaging. Furthermore, the developed fabrication scheme
enables producing AFM-SECM probes with integrated disk nanoelectrodes at
significantly reduced time and cost based on a highly reproducible semi-batch fabrication
process providing bifunctional probes at a wafer scale. The development of a detailed
processing strategy was accompanied by extensive simulation results for developing a
fundamental understanding on the electrochemical properties of AFM-SECM probes with
nanoscale electrodes, and for optimizing the associated processing parameters. Thus
fabricated probes were electrochemically characterized, and their performance was
demonstrated via bifunctional imaging at model samples.
The third part of this thesis describes the development and characterization of the
first AFM tip-integrated potentiometric sensors based on solid-state electrodes with submicrometer
dimensions enabling laterally resolved pH imaging. Antimony and iridium
oxides were applied as the pH sensitive electrode material, and have been integrated into
the AFM probes via conventional microfabrication strategies. The pH response of such
AFM tip-integrated integrated pH microsensors was tested for both material systems, and
first studies were performed demonstrating localized pH measurements at a model system.
44
Couceiro, José. "Wood shrinkage in CT-scanning analysis". Licentiate thesis, Luleå tekniska universitet, Träteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-129.
Testo completoAbstract (sommario):
Computed tomography (CT) can be used to study wood-water interactions in differentways, such as by determining wood moisture content (MC). The determination of MCrequires two CT images: one at the unknown moisture distribution and a second one ata known reference MC level, usually oven-dry MC. The two scans are then compared.If the goal is to determine the MC in local regions, when studying moisture gradients forinstance, wood shrinkage must be taken into account during the data processing of theimages. The anisotropy of wood shrinkage creates an obstacle, however, since theshrinkage is not uniform throughout the wood specimen. The objective of this thesis was to determine the shrinkage in wood in each pixel of aCT image. The work explores two different methods that estimate from CT images, thelocal shrinkage of a wood specimen between two different MC levels. The first methoddetermines shrinkage for each pixel using digital image correlation (DIC) and isembedded in a wider method to estimate the MC, which is the parameter verifiedagainst a reference. It involves several steps in different pieces of software, making ittime-consuming and creating many sources of possible experimental errors. The MCdetermined by this method showed a strong correlation with the gravimetricallymeasured MC, showing an R2 of 0.93 and the linear regression model predicted MCwith a RMSE of 1.4 MC percentage points. The second method uses the displacement information generated from the spatialalignment of the CT images in order to compute wood shrinkage in the radial andtangential directions. All the required steps are combined into a single computeralgorithm, which reduces the sources of error and facilitates the process. The RMSEbetween this method and the determination of shrinkage measured in the CT imagesusing CAD has shown acceptable small differences. Both methods have proved to be useful tools to deal with shrinkage in different ways byusing CT images. In one case MC was successfully estimated, being the shrinkagecalculation a necessary step in the process, and in the other case the radial and tangentialshrinkages were successfully estimated for each pixel. Nevertheless, the difficulty incomparing the shrinkage coefficient calculated for local regions with a reference valuesuggest that more research must be carried out in order to be able to draw reliableconclusions.
45
Ge, Yunfei. "Quantitative measurement using scanning thermal microscopy". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7474/.
Testo completoAbstract (sommario):
This thesis reports on the development of quantitative measurement using micromachined scanning thermal microscopy (SThM) probes. These thermal probes employ a resistive element at their end, which can be used in passive or active modes. With the help of a review of SThM, the current issues and potentials associated with this technique are revealed. As a consequence of this understanding, several experimental and theoretical methods are discussed, which expand our understanding of these probes. The whole thesis can be summarized into three parts, one focusing on the thermal probe, one on probe-sample thermal interactions, and the third on heat transfer within the sample. In the first part, a series of experiments are demonstrated, aimed at characterizing the probe in its electrical and thermal properties, benefiting advanced probe design, and laying a fundamental base for quantifying the temperature of the probe. The second part focuses on two artifacts observed during the thermal scans – one induced by topography and the other by air conduction. Correspondingly, two devices, probing these artifacts, are developed. A topography-free sample, utilizing a pattern transfer technique, minimises topography-related artifacts that limited the reliability of SThM data; a controlled temperature ‘Johnson noise device’, with multiple-heater design, offers a uniform, accurate, temperature distribution. Analyzing results of scan from these samples provides data for studying the thermal interactions within the probe and the tip-sample interface. In the final part, the observation is presented that quantification of measurements depends not only on an accurate measurement tool, but also on a deep understanding of the heat transfer within the sample resulting from the nanoscopic contact. It is believed that work in this thesis contributes to SThM gaining wider application in the scientific community.
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Gustafsson, Alexander. "Theoretical modeling of scanning tunneling microscopy". Doctoral thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-69012.
Testo completoAbstract (sommario):
The main body of this thesis describes how to calculate scanning tunneling microscopy (STM) images from first-principles methods. The theory is based on localized orbital density functional theory (DFT), whose limitations for large-vacuum STM models are resolved by propagating localized-basis wave functions close to the surface into the vacuum region in real space. A finite difference approximation is used to define the vacuum Hamiltonian, from which accurate vacuum wave functions are calculated using equations based on standard single-particle Green’s function techniques, and ultimately used to compute the conductance. By averaging over the lateral reciprocal space, the theory is compared to a series of high-quality experiments in the low- bias limit, concerning copper surfaces with adsorbed carbon monoxide (CO) species and adsorbate atoms, scanned by pure and CO-functionalized copper tips. The theory compares well to the experiments, and allows for further insights into the elastic tunneling regime. A second significant project in this thesis concerns first-principles calculations of a simple chemical reaction of a hydroxyl (oxygen-deuterium) monomer adsorbed on a copper surface. The reaction mechanism is provided by tunneling electrons that, via a finite electron-vibration coupling, trigger the deuterium atom to flip between two nearly identical configurational states along a frustrated rotational motion. The theory suggests that the reaction primarily occurs via nuclear tunneling for the deuterium atom through the estimated reaction barrier, and that over-barrier ladder climbing processes are unlikely.
47
Blackham, Ian George. "Scanning tunneling microscopy of electrode surfaces". Thesis, University of Oxford, 1992. https://ora.ox.ac.uk/objects/uuid:f9d27595-1177-406f-89a2-1448ac654dd3.
Testo completoAbstract (sommario):
A scanning tunneling microscope (STM) suitable for the in-situ study of electrode surfaces under electrochemical control has been developed. The system consists of commercially available software and feedback electronics, with a custom-built stage and electrochemical control. The stage incorporates an automatic coarse approach mechanism for ease of operation. Gold single crystal spheres (SCS) and gold on mica thin films have been studied as surfaces potentially suitable for samples in in-situ electrochemical STM experiments. Characteristic features of each surface have been identified. High resolution in-situ STM imaging of the electro-oxidation of a gold surface in a sulphuric acid electrolyte has been achieved. Surface rearrangement at potentials positive of the double layer region has been observed and correlated with cyclic voltammetry. As yet unexplained features resulting from biasing the surface at potentials negative of the double layer region are reported. In phosphate electrolyte, bulk surface oxide formation and the surface resulting from reduction of the oxide have been imaged. Some aspects of the direct electrochemistry of cytochrome c at 4,4' dithiodipyridine (SSBPY) modified gold electrodes have been investigated. In-situ FTIR showed the potential dependent orientation of adsorbed thiopyridine species, while ex-situ and in-situ STM studies showed a novel surface pitting process to be active. It is hypothesised the STM experiment itself induces the process to take place. Features attributable to cytochrome c molecules have been observed. Rearrangement of gold on mica surfaces, on exposure to certain aqueous solutions has been observed and the process is attributed to the interaction of the solutions with the original surface structure present.
48
Yee, Shannon. "Design of a scanning tunneling microscope". Connect to resource, 2007. http://hdl.handle.net/1811/25190.
Testo completoAbstract (sommario):
Thesis (Honors)--Ohio State University, 2007.Title from first page of PDF file. Document formatted into pages: contains 110 p.; also includes graphics. Includes bibliographical references (p. 108-110). Available online via Ohio State University's Knowledge Bank.
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Heard, P. J. "Applications of scanning ion beam lithography". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372653.
Testo completo
50
Liou, Je-Wen. "Scanning probe microscopy of photosynthetic membranes". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398112.
Testo completo