Dissertations / Theses on the topic 'Separation science'
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Hoettges, Kai F. "Miniaturisation in separation science : liquid-liquid separation on a chip." Thesis, University of Surrey, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252454.
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Clark, Jonathan Edward. "Unique Applications of Nanomaterials in Separation Science." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282335513.
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Nordborg, Anna. "Synthesis and modifications of materials for separation science." Doctoral thesis, Umeå : Department of Chemistry, Umeå University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1572.
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Zewe, Joseph William. "The Development of Novel Nanomaterials for Separation Science." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345485921.
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Houle, Michael E. "Weak separation of sets." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74229.
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Consider the following fundamental problem: given two sets R and G of objects positioned in d-dimensional Euclidean space, does there exist a surface of some specific type which separates the objects of R from the objects of G?Much attention has been given to this problem, for many classes of objects and separating surfaces. However, very few satisfactory alternatives exist when the objects are not separable by any of the surfaces of the chosen class. In this thesis, a new combinatorial measure of separability is proposed, based on the largest subset of the objects in $R cup G$ that may be separated using surfaces drawn from a certain class. The combinatorial and algorithmic questions arising from this weak separation measure are the main focus of the thesis. The strong relationship between the separable subsets of point sets and faces of hyperplane arrangements is investigated, and a variety of algorithms are presented for finding linear and spherical separators for point sets and sets of hyperspheres.
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Coughlin, Devin. "Type-Intertwined Separation Logic." Thesis, University of Colorado at Boulder, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3704668.
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Static program analysis can improve programmer productivity and software reliability by definitively ruling out entire classes of programmer mistakes. For mainstream imperative languages such as C, C++, and Java, static analysis about the heap---memory that is dynamically allocated at run time---is particularly challenging because heap memory acts as global, mutable state. This dissertation describes how to soundly combine two static analyses that each take vastly different approaches to reasoning about the heap: type systems and separation logic. Traditional type systems take an alias-agnostic, global view of the heap that affords both fast verification and light-weight annotation of invariants holding over the entire program. Separation logic, in contrast, provides an alias-aware, local view of the heap in which invariants can vary at each program point. In this work, I show how type systems and separation logic can be safely and efficiently combined. The result is type-intertwined separation logic, an analysis that applies traditional type-based reasoning to some regions of the program and separation logic to others---converting between analysis representations at region boundaries---and summarizes some portions of the heap with coarse type invariants and others with precise separation logic invariants. The key challenge that this dissertation addresses is the communication and preservation of heap invariants between analyses. I tackle this challenge with two core contributions. The first is type-consistent summarization and materialization, which enables type-intertwined separation logic to both leverage and selectively violate the global type invariant. This mechanism allows the analysis to efficiently and precisely verify invariants that hold almost everywhere. Second, I describe gated separating conjunction, a non-commutative strengthening of standard separating conjunction that expresses local dis-pointing relationships between sub-heaps. Gated separation enables local heap reasoning by permitting the separation logic to frame out portions of memory and prevent the type system from interfering with its contents---an operation that would be unsound in type-intertwined analysis with only standard separating conjunction. With these two contributions, type-intertwined separation logic combines the benefits of both type-like global reasoning and separation-logic-style local reasoning in a single analysis.
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Li, Yipeng. "Monaural Musical Sound Separation." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211994188.
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Sagar, Ambuj Daya. "Materials separation by dielectrophoresis." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14215.
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Newsome, Toni Elwell. "Development of Electrospun Nanomaterials and Their Applications in Separation Science." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1394798760.
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Beilke, Michael C. "The Development of Nanomaterials and "Green" Methods for Separation Science." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448475540.
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Emmott, John David. "Chromatographic separation of metals." Thesis, University of Central Lancashire, 2016. http://clok.uclan.ac.uk/16599/.
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In nuclear reprocessing, PUREX, a solvent extraction process, has long been the separation method employed for the separation of the bulk components of irradiated nuclear fuel (namely uranium and plutonium) from the fission products and other minor actinides produced during the fuel use. The uranium and plutonium constitutes approximately 96 % by mass of the irradiated fuel and for this to be removed, requires large volumes of extractant and equipment with large surface area contactors and therefore floor space requirements. The PUREX process has for nearly 60 years been the largely unchallenged separation technology for the reprocessing of irradiated fuel, for both nuclear weapon production and commercial nuclear power generation. The merits and ability of this process are unquestionable since it achieves the objectives of highly purified plutonium and uranium which both can be eventually recycled. Although well proven and predictable, the PUREX process is not without its challenges: the generation of significant quantities of highly active aqueous liquid containing fission products (FPs) and minor actinides (MAs), and the degradation of the solvent phase reagents and non-specific nature of the extractant TriButylPhosphate (TBP) may have contributed to only a fraction of the total annual output of irradiated fuel being reprocessed. Fission products are elements which are produced in a nuclear reactor and are the atomic fragments left after a large atomic nucleus (typically uranium-235) undergoes nuclear fission, splitting into two smaller nuclei, along with a few neutrons, the release of heat energy (kinetic energy of the nuclei), and gamma rays. Minor actinides such as neptunium, americium, curium, berkelium, californium, einsteinium, and fermium are the actinide elements in irradiated nuclear fuel other than uranium and plutonium; they are minor as they represent a very small proportion of actinides in comparison to U and Pu. This thesis explores the possibility of using a continuous chromatographic method to extract the lesser components of the irradiated fuel. One of the major problems with the use of chromatography as an industrial process is the expansion from the batch separations on the bench top to a continuous efficient process, capable of processing large volumes. This thesis, through existing concepts, will describe a proof of concept chromatographic separation of surrogates and isotopes of the components of irradiated fuels which can be readily scaled up to a continuous chromatographic separation. The project is a radical departure from PUREX and will offer many advantages over PUREX. It is based on the separation of FPs and MAs from uranium and plutonium isotopes using continuous chromatographic separation. This thesis assesses a number of commercial resins for their suitability for the proposed continuous chromatography reprocessing method. The experiments were all undertaken at elevated nitric acid concentrations and as such are describing interactions which are rarely required commercially and therefore seldom reported, with batch studies to assess separation factors between ions, uptake kinetics and isotherms over a range of nitric acid concentrations to more dynamic column breakthrough and eventually separations. The research demonstrates that a separation can be achieved at an elevated HNO3 concentration on a commercially available ion exchange resin.
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Long, Byron L. "Validity in a variant of separation logic." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3378369.
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Thesis (Ph.D.)--Indiana University, Dept. of Computer Science, 2009.Title from PDF t.p. (viewed on Jul 9, 2010). Source: Dissertation Abstracts International, Volume: 70-10, Section: B, page: 6348. Adviser: Daniel Leivant.
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Zhou, Yi. "Membrane-Based Gas Separation For Carbon Capture." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595254659184073.
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Paull, Brett. "Advancing the separation sciences through the delivery of new materials, technology and methodology." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1600.
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Separation science is a multi‐faceted discipline, underpinning almost all other fields of science and technology. Its scope encompasses fundamental and cutting edge processes and technologies, based upon exploitation of the physical distribution of chemical and biochemical species between solid, liquid or gaseous ‘phases’, facilitating their separation, purification, and analysis. Separation science plays a particularly pivotal element within the majority of modern analytical methods, methods which continue to support all manner of cutting edge scientific endeavour, including, for example, the current ‘‐Omics’ scientific revolution. As inferred above, separation science can of course vary considerably in physical form and scale, from micro‐extraction, to bench‐top chromatographic methods, to large scale industrial process isolation and preparative systems. However, in each and every case there exists several common factors governing success, perhaps the most significant of which is so‐called ‘phase selectivity’, or the fundamental chemical and biochemical interaction between a molecularly defined/controlled surface or phase, and the individual target or group of molecules.
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Chiu, William. "Processing of Supported Silica Membranes for Gas Separation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1349815421.
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Ratsameepakai, Waraporn. "Application of separation science and mass spectrometry to the analysis of fuels." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/392927/.
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Biodiesel has been used as alternative energy because of the shortage of petroleum fuel resources. Biodiesel is a mixture of fatty acid methyl esters (FAMEs) having different molecular structures with varying chain lengths, and levels of unsaturation. Electrochemistry-mass spectrometry (EC-MS) was used for investigation and monitoring oxidation products of FAMEs. Through direct coupling of this device to the electrospray ion source of the mass spectrometer typical oxidation products were observed in minutes compared to months/years for the auto-oxidation process. The efficiency of glassy carbon (GC) and magic diamond (MD) working electrodes was compared. Oxygenated species for methyl oleate (C18:1), methyl linoleate (C18:2) and methyl linolenate (C18:3) with up to +2(O), + 6(O), and + 9(O), (2.5 V, GC electrode) and +6(O), +8(O), and + 12(O) (3.0 V, MD electrode) respectively were observed. The potentials of oxidation increased in the order methyl esters of C18:3 < C18:2 < C18:1 for both MD and GC electrodes. The primary oxidation products, hydroperoxides-FAME, in the auto-oxidation of unsaturated FAMEs (C18:1, C18:2, C18:3) can undergo further oxidation to produces a numerous of volatile and non-volatile secondary oxidation products. The volatile oxidation products, e.g. 2,4-decadienal and methyl 9-oxo-nonanoate were observed in the gas chromatography-electron ionisation mass spectrometry (GC-EI MS) analyses whereas the less volatile species require electrospray ionisation (ESI) and chromatographic introduction of the samples. High performance liquid chromatography-electrospray ionisation mass spectrometry (HPLC-ESI MS), ultra-high performance liquid chromatography-electrospray ionisation mass spectrometry (UHPLC-ESI MS) and ultra-high performance supercritical fluid chromatography-electrospray ionisation mass spectrometry (UHPSFC-ESI MS) can be used for the separation of non-volatile species of the oxidation products. The elemental formula for these oxidised FAMEs were determined by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF MS) and infusion Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). The presence of oxygenated species up to 6 oxygen atoms of the ion at m/z 411.1999 [C19H32O8 + Na]+ with a 2.6 ppm error observed in positive ion ESI-FT-ICR MS. It expected as the hydroperoxy bis-cyclic peroxides from auto-oxidised methyl linolenate. Revision of the Energy Institute IP/585 reference method for quantitation of rapeseed methyl esters (RME) by GC-MS was required to afford quantitation of the short chain FAMEs in aviation turbine fuel (AVTUR) now appearing in certain geographic regions of the world. The revised method has delivered showed partial success and an improvement in qualitatively detecting and a positive move towards quantitation of the major components of coconut methyl ester (CME). HPLC and UHPLC coupled to MS offer alternative orthogonal approaches for analysis of these materials. The selective ionisation afforded by ESI affords ready detection of the FAMEs though the reversed-phase chromatography does not fully separate the FAME from the AVTUR fuel matrix, this would lead to matrix effects and ion suppression issues which could compromise any quantitative analysis. UHPSFC-MS provides a solution where the coconut methyl ester (CME) and rapeseed methyl ester (RME) are completely separated from the AVTUR whilst still delivering the benefits of the selective ionisation provided by the electrospray interface. Further supercritical fluid carbon dioxide (scCO2) is readily compatible with direct injection of the AVTUR fuel with the analytical benefits of supercritical fluid chromatography delivering base-line resolved peaks for all the FAMEs of interest in under 3 min.
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Yunus, Md Nurul Amziah. "Continuous dielectrophoretic separation of colloidal particles." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/79370/.
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Dielectrophoresis (DEP) is a technique that can be used to separate particle at microscale. It is of particular interest because it is a non-invasive, non-destructive and non-contact technique, which ensures that sample composition remains the same with only the particles being separated. On the microscale, DEP has been used to separate viable and non-viable cells, and cells with different dielectric properties, with the aid of a range of miniaturised, microfabricated devices. However, DEP at the nano-scale is a novel area and is still under research. Miniaturisation of devices in general has been an ongoing trend to improve the performance of analytical tools. In particular, processes for micro-device fabrication using dry film resist have been studied in order to reduce size, cost, sophisticated hardware usage and power consumption. This thesis presents an investigation into the novel design of dielectrophoretic particle separator, using rapid dry film resist methods to construct an integrated device. The development of analysis software for detecting particle movement in videos of experiments is presented, along with its use as a data analysis tool for determining particle position in the array. Characterisation measurements have been performed for a range of experimental parameters demonstrating the variability and behaviour of the device. Separation experiments were performed using test micron and submicron particles over a wide range of applied field frequencies, confirming the theoretical predictions and demonstrate the standard of separation efficiency. Preliminary investigations of other application of the device to larger particle and integrating micropump technology are also presented.
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Han, Yushen. "Score-informed musical source separation and reconstruction." Thesis, Indiana University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3609061.
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A systematic approach to retrieve individual parts in a monaural music recording with its score is introduced. We are interested in isolating the accompaniment part by removing the solo part from a recording of concerto music in which a solo instrument is accompanied by an orchestra. We require the music audio, the score, and optionally a sample library of individual notes played in isolation. Our approach is based on explicit knowledge of the musical audio at the semantic level (notes or chords) from an audio-score alignment. Such knowledge allows the spectrogram energy to be decomposed into note-based models that could be trained with the sample library. Our approach can be divided into: (1) "masking" to estimate a solo mask to remove the solo and (2) "reconstruction" to impute the missing harmonics of the orchestra notes that have been inevitably damaged in masking.
In "masking," we estimate a 2-dimensional binary mask to classify each time-frequency cell of the short-time Fourier Transform (STFT) spectrogram as either solo or accompaniment in STFT domain. We mainly employ an Expectation Maximization (EM) algorithm to decompose spectrogram magnitude into note-based models. In this process of "erasing" the soloist’s contribution to the mixture by applying the mask, the remaining orchestra is degraded. In "reconstruction," we propose a novel technique to repair such degradation. We use a state-space model for each note partial which is represented by a slowing-changing amplitude envelope and an "unwrapped" phase sequence. Such amplitude-phase representation can be computed by Kalman smoothing. It allows us to "transpose" intact partials of the orchestra part onto the degraded time-frequency region. Objective metrics and subjective listening are used on real and synthesized musical audio data for evaluation and parameter optimization.
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Sims, Elodie-Jane. "Pointer analysis and separation logic." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/506.
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Wang, Peidong. "Robust Automatic Speech Recognition By Integrating Speech Separation." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619099401042668.
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Patel, Krina. "Analysis of internal diesel injector deposit formation by separation science and mass spectrometry." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/411867/.
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Modern high pressure fuel injection equipment (FIE) has been developed to comply with stricter emission regulations and control of fossil fuel consumption in the petrochemical industry. This incorporates smaller diameter injection holes to promote atomisation and operation at higher pressures and temperatures. These new systems are more susceptible to internal diesel injector deposits (IDID) formation which can deteriorate engine performance causing a range of operational problems such as injector failure and filter blocking, leading to increased fuel usage and emission issues. The objectives of the project are to investigate the causes of IDID and develop analytical methods for possible deposit precursor species. A number of approaches where undertaken to investigate deposit formation. The solvency of fuel was investigated to determine if the fuels ability to dissolve particulates has an effect on deposit formation. A 10 peak data reduction model was developed to allow for quick and easy qualitative analysis of data and determination of aliphatic and aromatic components present in fuel. It was seen that injector and filter deposit samples showed greater amounts of high mass aliphatic content. A UHPSFC-MS screening method was also developed to identify steryl glucosides, the presence of SGs in biodiesel has been implicated in deposit formation as they show limited solubility. Tandem MS experiments were also explored to identify fragmentation patterns and aid in structure elucidation. Surface analysis was investigated to analyse the metal injector surfaces to characterise components that may be present in deposits. DART-MS and SEM-EDX were both explored for this. From the SEM-EDX data, three distinct regions were seen and a vast difference in topology was observed in the non-deposited region, a transitional region and deposited region. These different approaches worked well to give an overall understanding of the deposit formation issue and the complexity of the problem.
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Maiko, Khumo Gwendoline. "Multidimensional separation of complex polymers according to microstructure." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86227.
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Thesis (PhD)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Complex polymer systems have multiple distributions with regard to molecular parameters such as molar mass, functionality, chemical composition, molecular architecture and microstructure. These distributions affect the properties of the polymers making it necessary to develop separation methods to be able to correlate structure to property. A single onedimensional chromatographic method is usually not sufficient to separate these complex polymers with respect to all the distributions. Hence, multidimensional liquid chromatography is necessary for the complete analysis of complex polymers using two or more chromatographic techniques before detection. In this work, two novel liquid chromatographic methods were developed to separate complex polymers according to microstructure. Comprehensive two-dimensional liquid chromatography (LC x LC) was carried out to observe the correlation between microstructure and molar mass. The separation according to microstructure was coupled to NMR (LC-NMR) to observe, identify and quantify the different microstructural components during chromatographic elution. The first chromatographic method separated hydrogenated and deuterated polystyrene homopolymers with respect to the isotope effect. For the LC x LC experiments, liquid chromatography at critical conditions (LCCC) was employed as the first dimension separating according to the isotope effect and size exclusion chromatography (SEC) as the second dimension separating according to molar mass. The LC x LC results of the blends showed that there was an improvement in isotopic separation with an increase in molar mass. The LCNMR coupling using both 1H and 2H NMR detection allowed for the identification of low molar mass blend components which were not sufficiently separated by liquid chromatography. The second chromatographic method separated stereoregular poly(methyl methacrylate)s (PMMAs) with respect to tacticity. The LC x LC experiments of stereoregular PMMAs utilised solvent gradient liquid chromatography as the first dimension to separate according to tacticity and size exclusion chromatography (SEC) as the second dimension to separate according to molar mass. The LC x LC results showed a change in the triad composition with elution of the stereoregular PMMAs with a slight influence of molar mass. The LC-NMR coupling allowed the observation of the triad composition during chromatographic elution.
AFRIKAANSE OPSOMMING: Komplekse polimeriese sisteme het meervoudige verspreidings ten opsigte van molekulêre parameters, soos byvoorbeeld, molêre massa, funksionaliteit, chemiese samestelling, molekulêre argitektuur en mikrostruktuur. Hierdie verspreidings beïnvloed die eienskappe van die polimere en dus is dit nodig om skeidingsmetodes te ontwikkel ten einde polimeerstruktuur met polimeereienskappe te kan korreleer. ‘n Enkele een-dimensionele chromatografiese metode is gewoonlik nie voldoende om hierdie komplekse polimere te skei met betrekking tot al die verspreidings nie. Multidimensionele vloeistofchromatografie, met die insluiting van twee of meer chromatografiese tegnieke, is dus nodig om polimere te skei voor waarneming kan plaasvind. Twee nuwe chromatografiese metodes is ontwikkel om komplekse polimere volgens mikrostruktuur te skei. Twee-dimensionele vloeistofchromatografie (LC x LC) is uitgevoer ten einde die korrelasie tussen mikrostruktuur en molêre massa te ondersoek. Daarna is die skeiding wat op mikrostruktuur gebasseer is, gekoppel aan KMR (LC-KMR) om die verskillende mikrostrukturele komponente gedurende chromatografiese eluering waar te neem, te identifiseer en te kwantifiseer. Die eerste chromatografiese metode het die gehidrogeneerde en gedeutereerde polistireen geskei met betrekking tot die isotoopeffek. Hier het die LC x LC skeiding bestaan uit vloeistofchromatografie onder kritiese kondisies (LCCC) as die eerste dimensie, wat skeiding bewerkstellig het gebasseer op die isotoopeffek, en grootte-uitsluitingschromatografie (SEC) as die tweede dimensie, wat skeiding bewerkstellig het gebasseer op die molêre massa. Die LC x LC resultate van die vermengings het ‘n verbetering in isotopiese skeiding met ‘n toename in molêre massa getoon. Deur gebruik te maak van die LC-KMR koppeling, waar beide 1H en 2H KMR waarneming gebruik is, was dit moontlik om die lae-molêre-massakomponente van vermengings wat nie volledig d.m.v. LC geskei kon word nie, te identifiseer. Die tweede chromatografiese metode het stereoreëlmatige polimetielmetakrilate (PMMAs) m.b.t. taktisiteit geskei. Die LC x LC skeiding van stereoreëlmatige PMMAs het bestaan uit oplosmiddel -gradiënt-LC as eerste dimensie om volgens taktisiteit te skei, en SEC as tweede dimensie om volgens molêre massa te skei. Die LC x LC resultate het ‘n molêre massa afhanklikheid van stereoreëlmatige PMMAs op taktisiteit getoon. Die LC-KMR koppeling het dit moontlik gemaak om die triade-samestelling gedurende chromatografiese eluering waar te neem.
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Joakim, Valberg. "Document Separation in Digital Mailrooms." Thesis, Linköpings universitet, Artificiell intelligens och integrerad datorsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122406.
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The growing mail volumes for businesses worldwide is one reason why theyare increasingly turning to digital mailrooms. A digital mailroom automaticallymanages the incoming mails, and a vital technology to its success isdocument classication. A problem with digital mailrooms and the documentclassication is separating the input stream of pages into documents.This thesis investigates existing classication theory and applies it to createan algorithm which solves the document separation problem. This algorithmis evaluated and compared against an existing algorithmic solution, over adataset containing real invoices.
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Bow, Hansen Chang. "Characterization of nanofilter arrays for small molecule separation." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37934.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 59-60).
Experimental studies were performed to evaluate methods of improving separation resolution and speed in microfabricated nanofilter arrays. Experiment parameters investigated include electric field strength, nanofilter geometry, and buffer concentration. DNA polymers of size 25-1000 base pairs were the subject of our study. We concluded that increasing electric field strength resulted in inferior separation for larger DNA polymers (400-1000 bp). Additionally, we quantified the improvement in resolution of smaller nanofilter pores and lower buffer concentration. A theoretical model based on Macrotransport Theory was developed to estimate average species velocity and peak dispersion.
by Hansen Chang Bow.
S.M.
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Bronson, James. "An exploration of complex matrix factorization as a tool for single-channel musical source separation." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121548.
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Since the introduction of non-negative matrix factorization (NMF) as a tool for single-channel musical source separation (SC-MSS) in the early part of the 21st century, it has steadily increased both in practicality and popularity, and continues to be a major area of focus within the signal processing community. It is acknowledged in the literature, however, that the fundamental assumption of the mixture model for the spectral representation of the acoustic sources, to which NMF is applied, violates the true nature of the superposition of acoustic signals by disregarding the phase relationship between overlapping sources. It is also recognized that NMF-based source separation procedures require additional post-processing, in order to reincorporate the phase information back into the spectral representation of the sources, once the factorization is complete. This thesis explores Complex Matrix Factorization (CMF), a recently proposed variant of NMF, which incorporates the phase information of the acoustic sources into the matrix factorization framework, allowing for the development of source separation procedures founded on a mixture model rooted in the complex-spectrum domain (in which the superposition of overlapping sources is preserved). CMF has the additional benefit of integrating the estimation of the phase of the constituent sources directly into the factorization algorithm, eliminating the need for post-factorization phase estimation. Three experiments were conducted, investigating the behaviour of CMF, as it compares to NMF, when applied to simple test mixtures constructed from overlapping acoustic instruments. The main contribution of this thesis is the development of a physically motivated phase-based constraint, which restricts the relation between the phase parameter estimates over time. The CMF-based separation procedure, armed with this novel phase constraint, is demonstrated to offer promising results when employed as a tool for SC-MSS on the simple acoustic test case considered.Depuis l'introduction de la factorisation en matrices non-négatives (NMF) en tant qu'outil pour la séparation de sources musicales monophoniques (SC-MSS) au début du 21e siècle, son utilité et sa popularité ont augmenté de façon régulière et elle continue d'être un grand domaine d'intérêt au sein de la communauté de traitement du signal. Cependant, il est reconnu dans la littérature sur le sujet que l'hypothèse fondamentale du modèle de mélange pour la représentation spectrale de la source acoustique, à laquelle la NMF est appliquée, enfreint la véritable nature de la superposition des signaux acoustiques en ignorant la combinaison de phase entre sources superposées. Il est aussi reconnu que les procédures de type NMF pour la séparation de sources nécessitent des procédures de post-traitement additionnelles pour réintégrer l'information de phase à la représentation spectrale des sources une fois la factorisation complétée. Cette thèse explore la factorisation de matrices complexes (CMF), une variante de la NMF récemment proposée qui intègre l'information de phase des sources acoustiques dans le cadre de la factorisation de matrices. Ceci permet le développement de procédures de séparation de sources fondées sur un modèle de mixage ancré dans le domaine des spectres complexes (dans lequel le mélange de sources qui se superposent est préservée). La CMF apporte aussi l'avantage d'intégrer l'estimation de la phase des sources constituantes directement à l'algorithme de factorisation, ce qui élimine le besoin d'estimation de phase a posteriori. Trois expériences ont été réalisées afin d'étudier le comportement de la CMF comparé à la NMF lorsqu'appliqué à des mélanges simples fait à partir d'instruments acoustiques qui se superposent. La principale contribution de cette thèse est la formalisation d'une contrainte de phase, fondée sur des propriétés physiques, qui impose des liens entre ses estimations au court du temps. Nous montrons que l'algorithme de la CMF, armée de cette nouvelle contrainte de phase, donne des résultats prometteurs lorsqu'il est utilisé sur des signaux acoustiques simples dans le cadre de la SC-MSS.
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Lee, Chia-Hua. "Development of biomimetic microfluidic adhesive substrates for cell separation." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/88374.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Cell separation is important in medical, biological research, clinical therapy, diagnostics and many other areas. The conventional methods of cell sorting have limited applications due to sophisticated equipment settings, high costs, or time-intensive and labor-intensive processing steps. Inspired from natural cell sorting system-cell rolling, a novel microfluidic device design was proposed for point-of-care and point-of-use applications. It relies on interaction of cells with biomimetic adhesive substrates comprising multiple inclined, asymmetric bands of weak adhesive molecules. Such device design allows continuous sorting of cells without irreversible capture of cells. To realize such device, comprehensive studies of how cells settle onto the substrate, how cells capture by the substrate, the effect of substrate parameters on separation potential, and selection of adhesion molecules are needed to optimize device performance. In this thesis, first, how the cells settle and how they are captured by the receptors were studied using HL60 cells as a model leukocyte cell line and P-selectin as a model receptor. Settling distance of HL60 cells under different shear stresses inside microfluidic channels was identified from the study of convection velocity of cells at different position along the channel. The results show that settling distance increases with increasing shear stress. Cell capture was then quantified by characterizing how far settled HL60 cells travelled before they were captured by P-selectin molecules, defined as the attachment distance. Cumulative probabilities of attachment distance of cells at different shear stresses revealed that increasing shear stress results in exponential increase of the attachment distance of cells by receptor molecules. An empirical model was developed to predict capture probability by an inclined receptor band and the prediction value was verified by experimental data from a device. Second, a patterning method involving microcontact printing was developed to create biomimetic adhesive substrates comprising multiple inclined receptor bands of P-selectin molecules. The patterned substrates were then used to study how transport of HL60 cells can be controlled by the substrate parameters including pattern inclination angle with respect to shear flow direction, shear stress magnitude, and P-selectin incubation concentration. The effects of substrate parameters were quantified in terms of the edge tracking length, lateral displacement, and the rolling velocity. The edge inclination angle was identified as the strongest modulator of edge tracking length on a single band for captured cells. To study optimization of the device design, experimental data of cell settling, cell attachment, and edge tracking length were integrated into a model to predict device performance including device capture efficiency and total lateral displacement. General guidelines for microfluidic device design were established based on the results from the model: smaller band width, edge angle of 15-20°, and lower shear stress. Finally, to develop new specific receptor-ligand systems, M13 pVIII and pIll phage libraries were used for selecting peptides with affinity to CD4 proteins. Screened phage from pVIII library was immobilized on the gold surface and capture efficiency of CD4+ cells were characterized. The interaction between selectin phage and CD4+ cells were demonstrated to be CD4-dependent. Moreover, the selected phage from pIII library and the corresponding synthetic peptides were demonstrated to exhibit specificity to CD4 proteins. In summary, this thesis focuses on development of biomimetic adhesive substrates for microfluidic devices involving transient interactions between the cells and the receptor-patterned substrates. How cells flow and get captured by patterned biomimetic substrates inside the microfluidic channels, how substrates parameters affect cell rolling trajectories and device performance, and how to identify new receptor-ligand systems were discussed in this thesis. This study has led to realization of a microfluidic device for separating neutrophils from blood. This microfluidic system provides continuous sorting without irreversible capture of cells, and is believed to be an effective method that can potentially be used in many point-of-care applications. Keywords: microfluidics, cell separation, cell rolling, selectin, biopanning, M13
by Chia-Hua Lee.
Ph. D.
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Osborne, Zoe Ann. "Nucleation kinetics of phase separation in a sodium silicate glass." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/284320.
Full textAbstract:
This study was undertaken with the goal of comparing the calculated nucleation rate for phase separation with experimental measurements for a simple glass system. The magnitude and the temperature dependence of the nucleation rate for a sodium silicate glass composition in the binodal regime was calculated. These calculations used a minimum of assumptions in order to determine the limits on certain thermodynamic variables, chiefly surface energy. Many of the values used in these calculations were determined from growth and coarsening measurements made on this system. Nucleation rates, as well as growth and coarsening rates, were then measured in this system for this comparison to theory. It was found that the free energy of mixing models are unable to predict nucleation behavior at temperatures near the immiscibility boundary. In addition, these models predict that the nucleating composition lies outside of the binodal. Although the values measured for the activation energy correspond well to those in the literature, their incorporation into the nucleation expression does not correct for the temperature behavior of the free energy of mixing. It is also unlikely that a temperature dependent surface energy term could account for the poor predictive nature of classical nucleation theory at small undercoolings.
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KULKARNI, AMIT S. "REACTION INDUCED PHASE-SEPARATION CONTROLLED BY MOLECULAR TOPOLOGY." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1108001435.
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Mueller, Amy 1980. "Iterative blind separation of Gaussian data of unknown order." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28457.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 125-126).
A method for blind separation of noisy jointly Gaussian multivariate signals X is presented, where X = AP + N, X is an observed set of vectors, A is the mixing matrix, P is the unknown signal matrix, and N is white noise. The objective is to estimate all matrices on the right-hand side when even their dimensions (the system order) are unknown. The algorithms developed are extensions of the Iterative Order and Noise (ION) estimation algorithm [10]. Improvements made within the iterative structure of ION to better estimate the order and noise yield ION'. The addition of a second-order blind identification algorithm (SOBI, [4]) subsequently yields ONA, which fully characterizes a data set by estimating the (O)rder, (N)oise, and mixing matrix (A). Metrics are developed to evaluate the performance of these algorithms, and their applicability is discussed. Optimum algorithm constants for ION' and ONA are derived, and their range of applicability is outlined. The algorithms are evaluated through application to three types of data: (1) simulated Gaussian data which spans the problem space, (2) a set of non-Gaussian factory data with 577 variables, and (3) a hyperspectral image with 224 channels. The ONA algorithm is extended to 2D (spatial) hyperspectral problems by exploiting spatial rather than time correlation. ONA produces a full characterization of the data with high signal-to-noise ratios for most unknown parameters in the Gaussian case, though the jointly Gaussian P is shown to be most difficult to retrieve. In all three cases, ONA reduces the noise in the data, identifies small sets of highly correlated variables, and unmixes latent signals. The spatial ONA identifies surface features in the hyperspectral image and retrieves sources
(cont.) significantly more independent than those retrieved by PCA. Further exploration of the applicability of these algorithms to other types of data and further algorithmic improvement is recommended.
by Amy Mueller.
M.Eng.
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Zhao, Yan. "Droplet microfluidics for biomolecule separation and detection." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/379292/.
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Droplet microfluidics is a new approach for chemical and biological analysis. Discrete nano-litre droplets ensure chemical reactions occur quickly without cross-talk, allowing samples to be processed without dispersion. Droplet microfluidics is effectively a digital sample processing platform enabling sample droplets to be handled in a continuous serial format. This thesis describes a method for in situ compartmentalization of biological and chemical samples after separation using Slipchip technology. Isoelectric focusing (IEF) was used to separate biomolecules within the Slipchip. The device was used to compartmentalise the IEF separated samples into micro-droplets. This approach solves the compartmentalization challenge faced by current IEF systems. The digitised sample droplets can be collected serially or in parallel. In serial collection, droplets are collected in tubing that maintains their spatial sequence. For parallel collection, droplets are collected with a multi-pipette. Separated samples were assayed by gel electrophoresis on an Agilent Bioanalyzer. Separated samples were also postprocessed on-chip by mixing with pH indicator droplets for calibration of droplet pH. Such continuous-flow/micro-droplet conversion methods have the potential of hyphenating different separation techniques for performing advanced analysis of complex samples. One disadvantage with droplet microfluidics is the very small dimensions of the sample meaning that classical absorption assays are difficult. Therefore, a high sensitivity absorption-based optical method called Cavity Ring Down Spectroscopy (CRDS) was developed and evaluated. The integration of CRDS with microfluidic devices was explored. Microfabricated cylindrical lenses were used to increase the light coupling efficiency within a chip, but results showed that light losses in the system were too high to enable the effective use of CRDS for analysis.
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Park, Edward S. 1974. "Microfabricated magnetophoretic focusing systems for the separation of submicrometer particles." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32268.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references.
Magnetic separation is an actively researched field due to its broad applicability to the mineral, chemical, and biological industries. The objective of this work was to design, fabricate, and test systems to study magnetophoresis of particles in suspension. To achieve this goal, two system concepts were developed: an Alternating Field System and a Flow System. Both systems consisted of permanent magnets and miniaturized devices (separation chips), which integrated microfluidic channels with ferromagnetic core elements. The systems produced "sawtooth" magnetic fields that were combined with a long-range magnetic field or pressure- driven flow to bring about migration, focusing and trapping of nonmagnetic particles suspended in ferrofluid. A potential application of such systems is high-resolution, size-based separation of DNA, cellular organelles, viruses, and other like-sized biological entities. The systems were designed using finite element analysis and fabricated using IC/MEMS microfabrication techniques. The fabrication process for the separation chips realized a microfluidic channel and electroplating molds in a single layer of SU-8 photoresist on a glass substrate. Nickel core elements were electroplated into the molds, and a PDMS cover substrate was attached using a novel technique involving contact bond and heat cycling. The systems were tested via experiments using optical fluorescence methods to observe the concentration profiles of polydisperse suspensions of polystyrene beads.
(cont.) Alternating Field System involved simple migration under a long-range magnetic field, focusing under a sawtooth magnetic field, and attempted separation by combining the long-range and sawtooth fields. The most significant findings of the trials were the significant effect of particle- particle interactions and high sensitivity to the core design of the chip. The Flow System trials combined a sawtooth field with flow. The trials demonstrated size-based trapping of particles, where 840 nm beads were trapped earlier along a separation channel, while 510 nm beads were trapped further along. Moreover, the location along the channel at which particles of a given size were trapped was shown to be a function of flow rate. Size-based trapping in magnetic potential wells, as well as flow rate tuning, could form the basis of a high-resolution particle separation system.
by Edward S. Park.
S.M.
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Jacob, Silva Paulo H. "Curvature driven phase separation in mixed ligand coated gold nanoparticles." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35065.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (leaves 31-33).
Monolayer-coated gold nanoparticles have been the subject of extensive studies in fields ranging from physics to medicine. The properties of these nanomaterials such as solubility and surface energy are often attributed solely to the chemical functionalities of the ligand head-groups. However, the morphology of these monomolecular layers on gold nanoparticles plays as important of a role as the surface chemistry. Intriguing phase-separation phenomena have been observed for mixed self-assembled monolayers (SAM) of octanethiol (OT) and mercaptopropionic acid (MPA) on the surface of gold nanoparticles. These ordered structures are studied here through scanning tunneling microscope (STM) images, as a function of the gold core diameter, which is a measure of the particle's curvature. The packing of OT homoligand nanoparticles is found to have a head-group spacing of 0.54 nm, which differs from that on flat gold (111) surfaces, 0.5 nm. The OT:MPA heteroligand nanoparticles are observed to phase-separate into ordered ribbon-like domains, with spacings that depend on the nanoparticle diameter. A geometric framework that includes a continuous and crystallographic description is established to best describe the observed behaviors.
by Paulo H. Jacob Silva.
S.B.
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Ransom, Sara L. (Sara Louise) 1976. "Investigation of phase separation in GaInAsSb using transmission electron microscopy." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50484.
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Romero, Macias Cristina. "Image understanding for automatic human and machine separation." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8640.
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The research presented in this thesis aims to extend the capabilities of human interaction proofs in order to improve security in web applications and services. The research focuses on developing a more robust and efficient Completely Automated Public Turing test to tell Computers and Human Apart (CAPTCHA) to increase the gap between human recognition and machine recognition. Two main novel approaches are presented, each one of them targeting a different area of human and machine recognition: a character recognition test, and an image recognition test. Along with the novel approaches, a categorisation for the available CAPTCHA methods is also introduced. The character recognition CAPTCHA is based on the creation of depth perception by using shadows to represent characters. The characters are created by the imaginary shadows produced by a light source, using as a basis the gestalt principle that human beings can perceive whole forms instead of just a collection of simple lines and curves. This approach was developed in two stages: firstly, two dimensional characters, and secondly three-dimensional character models. The image recognition CAPTCHA is based on the creation of cartoons out of faces. The faces used belong to people in the entertainment business, politicians, and sportsmen. The principal basis of this approach is that face perception is a cognitive process that humans perform easily and with a high rate of success. The process involves the use of face morphing techniques to distort the faces into cartoons, allowing the resulting image to be more robust against machine recognition. Exhaustive tests on both approaches using OCR software, SIFT image recognition, and face recognition software show an improvement in human recognition rate, whilst preventing robots break through the tests.
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Chokalingam, Kumar. "Poly (Allylamine Hydrochloride) and Poly (Acrylic Acid) Multilayers for Gas Separation." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1187019230.
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Han, Kun. "Supervised Speech Separation And Processing." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407865723.
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Kringle, Amy. "Separation and Characterization of Reconstituted Skim Milk Powder Treated with Mineral Chelators." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1556.
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The proteins found in milk are largely important in the functionality of many dairy products and dairy processes. The casein micelle system in milk is a complex and highly studied system. The micelle is thought to be a sponge like structure containing four caseins, αs1, αs2, β, and κ casein, and bound together with colloidal calcium phosphate. When a chelating agent such as a citrate, phosphate, or polyphosphate are added to milk systems, the CCP is bound to the chelator and removed from the micelle. It has been shown through past research that the use of calcium chelating agents disrupts the calcium phosphate equilibrium and allows for the dissociation of the casein micelle and release of the individual caseins. Once the caseins are disrupted from micellar form and in solution, it may be possible to separate out different casein streams for functional usage in dairy products using common separation techniques.
This thesis project seeks to evaluate the feasibility of separating milk treated with calcium chelators using various separation techniques to evaluate the individual casein fractions of this disrupted system. Four separation methods (ultracentrifugation, membrane filtration, heat coagulation, and coagulation based on pH) were employed to separate out the caseins based on selected properties, specifically density, molecular weight, and solubility. In ultracentrifugation, three speeds were tested, the heat coagulation study tested two temperatures, and pH based coagulation tested four different pHs to determine their impact on overall protein levels and individual casein yields. Skim milk powder was reconstituted and chelator was added at 1, 50, or 100 mEq/L treatment level. These samples were then separated using aforementioned techniques, and the supernatant or permeate was analyzed for total protein content, individual casein composition, turbidity, and mean particle size.
Analysis of centrifugal separation studies shows the interaction between chelator type, chelator level, and centrifugation speed had a significant impact on the amount of protein released from the casein micelle (p
Coagulation trials based on pH were also shown to have a significant interaction between chelator type, chelator level, and sample pH effecting the protein levels and casein composition (p
Membrane filtration showed low protein yields in permeate, however trisodium citrate 100 mEq was still shown to have significantly higher permeate % protein levels (p
The use of heat based coagulation as an individual casein separation technique for chelated samples is not recommended, as the casein micelle system itself is extremely heat stable, and the use of calcium chelators only increases the heat stability further. Because of the increased heat stability, no coagulum was formed in samples upon heating, and therefore, no separation and analysis could be done.
Improving our knowledge of pretreatment of milk prior to separation and the effectiveness of different separation methods on chelated milk products may result in information leading to the ability to separate out milk fractions that provide unique or improved properties for product applications.
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Ciucci, Sara, Yan Ge, Claudio Durán, Alessandra Palladini, Víctor Jiménez-Jiménez, Luisa María Martínez-Sánchez, Yutin Wang, et al. "Enlightening discriminative network functional modules behind Principal Component Analysis separation in differential-omic science studies." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-226961.
Full textAbstract:
Omic science is rapidly growing and one of the most employed techniques to explore differential patterns in omic datasets is principal component analysis (PCA). However, a method to enlighten the network of omic features that mostly contribute to the sample separation obtained by PCA is missing. An alternative is to build correlation networks between univariately-selected significant omic features, but this neglects the multivariate unsupervised feature compression responsible for the PCA sample segregation. Biologists and medical researchers often prefer effective methods that offer an immediate interpretation to complicated algorithms that in principle promise an improvement but in practice are difficult to be applied and interpreted. Here we present PC-corr: a simple algorithm that associates to any PCA segregation a discriminative network of features. Such network can be inspected in search of functional modules useful in the definition of combinatorial and multiscale biomarkers from multifaceted omic data in systems and precision biomedicine. We offer proofs of PC-corr efficacy on lipidomic, metagenomic, developmental genomic, population genetic, cancer promoteromic and cancer stem-cell mechanomic data. Finally, PC-corr is a general functional network inference approach that can be easily adopted for big data exploration in computer science and analysis of complex systems in physics.
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Hoffman, Elizabeth N. Barsoum M. W. "Carbide derived carbon from MAX-phases and their separation applications /." Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1120.
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Hussain, Abid. "Dielectric properties and microwave assisted separation of eggshell and membrane." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67033.
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Eggshell and membranes which are largely disposed of as waste are a reserve of many bioactive compounds with high economic and monetary value which can be extracted by the efficient separation of eggshell and membrane. Hence, this study concentrates on finding a suitable method for separating the eggshell from membrane. First, the effect of microwave treatment on separation of eggshell and membrane was investigated. The response of a material to electromagnetic radiation depends upon its dielectric properties; therefore, the study of the dielectric properties of eggshell and membrane was carried out in the range of 200 MHz to 20 GHz and in the temperature range of 25 0C to 100 0C. Also, the possibility of using this technique for detection of protein denaturation in egg membrane and shell was investigated. In the second part of the study, the effectiveness of microwave treatment on separation of eggshell and membrane was analyzed in terms of reduction in total energy required to separate the eggshell and membrane and was termed as bond energy. For all microwave treatments, three factors with three levels each were considered. Microwave treatment of eggs significantly reduced the bond energy between eggshell and membrane. A Model for calculating the bond energy between the eggshell and membrane for all microwave treatments was established.Généralement rejetées, les coquilles et membranes d'œuf représentent une importante réserve de composés bioactifs ayant une grande valeur économique et pécuniare, cette étude se concentre donc sur le problème de trower une méthode appropriée pour séparer la coquille de la membrane. Premièrement, notre étude évalua l'effet d'un traitement aux micro-ondes sur l'aise de séparation de la membrane de la coquille. Comme la réaction d'un matériel aux rayonnements électromagnétiques dépend de ses propriétés diélectriques, les propriétés diélectriques de coquilles et membranes furent donc indépendamment évaluées dans une gamme de frequencies de 200 MHz à 20GHz, en combinaison avec des températures variant de 25°C à 100°C. De plus, la possibilité d'utiliser cette technique pour détecter la dénaturation des protéines membranaires fut évaluée. En second lieu, l'efficacité du traitement aux micro-ondes à faciliter la séparation de la membrane de la coquille fut éprouvée en fonction de la réduction en énergie necessaire à cette séparation, soit l'énergie de liaison. Pour l'ensemble des traitements aux micro-ondes, trois facteurs à trois niveaux chacun furent évalués. Le traitement aux micro-ondes réduisit de façon significative l'énergie de liaison entre la membrane et la coquille. Un modèle fut développé permettant le calcul de l'énergie de liaison entre membrane et coquille, sous les divers traitements aux micro-ondes et selon les différents facteurs.
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Reyes, González Noel I. (Noel Iván). "Pulsed field separation of biomolecules in a nanofluidic filter array." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37076.
Full textAbstract:
Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006."February 3, 2006."
Includes bibliographical references (leaf 42).
In this work, pulsed electric fields are introduced as a means to enhance separation efficiency of biomolecules in a nanofluidic filter array channel. Separation under pulsed fields was tested using PBR322 DNA, Lambda Hind III DNA, and a sample containing three SDS denatured proteins. Pulsed fields are divided into long pulse and short pulse regimes, depending on how long the duration of the higher electric field pulse is compared to the average trapping time of a molecule in a single nanofluidic filter. It was found that under long pulse fields, the separation selectivity cannot be enhanced since the difference in velocity between two different molecules will always be a weighted average of the velocity at the high and low field levels of the pulsed field. On the other hand, application of pulsed fields in the short pulse regime yielded more promising results. After the pulse duration became comparable to the average trapping time of migrating molecules, the average velocity of molecules decreased with a reduction in the pulse duration. Certain bands within a sample were slowed down more than others by appropriately choosing the pulse duration, therefore resulting in increased selectivity and higher separation efficiency.
(cont.) For PBR322 DNA, separation resolution of up to 2.54 was obtained in under 15 minutes when the pulse duration was decreased down to 5ms. Novel experiments are proposed to achieve separation through band selective elution and bidirectional transport. A probabilistic model based on the binomial distribution is also proposed as a method to estimate the average velocity of molecules in the short pulse regime.
by Noel I. Reyes González.
M.Eng.and S.B.
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Herring, Keith 1981. "Blind separation of noisy multivariate data using second-order statistics." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30173.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (leaves 81-83).
A second-order method for blind source separation of noisy instantaneous linear mixtures is presented and analyzed for the case where the signal order k and noise covariance GG-H are unknown. Only a data set X of dimension n > k and of sample size m is observed, where X = AP + GW. The quality of separation depends on source-observation ratio k/n, the degree of spectral diversity, and the second-order non-stationarity of the underlying sources. The algorithm estimates the Second-Order separation transform A, the signal Order, and Noise, and is therefore referred to as SOON. SOON iteratively estimates: 1) k using a scree metric, and 2) the values of AP, G, and W using the Expectation-Maximization (EM) algorithm, where W is white noise and G is diagonal. The final step estimates A and the set of k underlying sources P using a variant of the joint diagonalization method, where P has k independent unit-variance elements. Tests using simulated Auto Regressive (AR) gaussian data show that SOON improves the quality of source separation in comparison to the standard second-order separation algorithms, i.e., Second-Order Blind Identification (SOBI) [3] and Second-Order Non-Stationary (SONS) blind identification [4]. The sensitivity in performance of SONS and SOON to several algorithmic parameters is also displayed in these experiments. To reduce sensitivities in the pre-whitening step of these algorithms, a heuristic is proposed by this thesis for whitening the data set; it is shown to improve separation performance. Additionally the application of blind source separation techniques to remote sensing data is discussed.
(cont.) Analysis of remote sensing data collected by the AVIRIS multichannel visible/infrared imaging instrument shows that SOON reveals physically significant dynamics within the data not found by the traditional methods of Principal Component Analysis (PCA) and Noise Adjusted Principal Component Analysis (NAPCA).
by Keith Herring.
S.M.
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Huang, Ying-zong. "Model-code separation architectures for compression based on message-passing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97802.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-142) and index.
Data is compressible by presuming a priori knowledge known as a data model, and applying an appropriate encoding to produce a shorter description. The two aspects of compression data modeling and coding - however are not always conceived as distinct, nor implemented as such in compression systems, leading to difficulties of an architectural nature. For example, how would one make improvements upon a data model whose specific form has been standardized into the encoding and decoding processes? How would one design coding for new types of data such as in biology and finance, without creating a new system in each case? How would one compress data that has been encrypted when the conventional encoder requires data-in-the-clear to extract redundancy? And how would mobile acquisition devices obtain good compression with lightweight encoders? These and many other challenges can be tackled by an alternative compression architecture. This work contributes a complete "model-code separation" system architecture for compression, based on a core set of iterative message-passing algorithms over graphical models representing the modeling and coding aspects of compression. Systems following this architecture resolve the challenges posed by current systems, and stand to benefit further from future advances in the understanding of data and the algorithms that process them. In the main portion of this thesis, the lossless compression of binary sources is examined. Examples are compressed under the proposed architecture and compared against some of the best systems today and to theoretical limits. They show that the flexibility of model-code separation does not incur a performance penalty. Indeed, the compression performance of such systems is competitive with and sometimes superior to existing solutions. The architecture is further extended to diverse situations of practical interest, such as mismatched and partially known models, different data and code alphabets, and lossy compression. In the process, insights into model uncertainty and universality, data representation and alphabet translation, and model-quantizer separation and low-complexity quantizer design are revealed. In many ways, the proposed architecture is uniquely suitable for understanding and tackling these problems. Throughout, a discourse is maintained over architectural and complexity issues, with a view toward practical implementability. Of interest to system designers, issues such as rate selection, doping, and code selection are addressed, and a method similar to EXIT-chart analysis is developed for evaluating when compression is possible. Suggestions for system interfaces and algorithmic factorization are distilled, and examples showing compression with realistic data and tasks are given to complete the description of a system architecture accessible to broader adoption. Ultimately, this work develops one architecturally principled approach toward flexible, modular, and extensible compression system design, with practical benefits. More broadly, it represents the beginning of many directions for promising research at the intersection of data compression, information theory, machine learning, coding, and random algorithms.
by Ying-zong Huang.
Ph. D.
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McCleese, Christopher. "Femtosecond Time-Resolved Spectroscopy Studies of Interfacial Charge Separation Processes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case149182204612303.
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Park, Mansoo Ph D. Massachusetts Institute of Technology. "Design of bulk nanocrystalline tungsten alloys via nano-phase separation sintering." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98166.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 96-100).
An accelerated sintering method called 'nano-phase separation sintering' is developed, with specific applicability to nanostructured tungsten alloys. Nanocrystalline tungsten alloys containing minority additions of chromium are produced by high-energy ball milling and then consolidated. Such alloys exhibit the onset of sintering at a very low temperature around 950 °C and a very rapid rate of densification. The mechanism of this accelerated sintering is established through understanding the role of nano-scale, solid second phase precipitation during the sintering cycle, as analyzed by thermomechanical analysis, electron microscopy and x-ray diffraction. In addition, control experiments are used to establish that the accelerated sintering is apparently accomplished from the combination of two features of the powders: (i) nanocrystallinity and (ii) alloy supersaturation. In addition to accelerating sintering, the incorporation of alloying elements and second phases are also beneficial for mitigating grain growth during a thermal cycle, so nanophase separation sintering is thus naturally appropriate to the production of fine-grained bulk materials. Sintered compacts achieved through nano-phase separation sintering display 10~30 times smaller grain sizes at comparable densities than those produced by conventional accelerated sintering methods such as solid-state activated sintering and liquid phase sintering. The thermodynamic features and conditions for nano-phase separation sintering are further explored based on the binary phase diagram in order to generalize the concept to other alloy systems. After presenting a series of proposed alloy design rules, the consolidation of chromium with an addition of nickel is accelerated. Prospects of the technique for the development of full density bulk products in more complex alloy systems are also discussed.
by Mansoo Park.
Ph. D.
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Kharechko, Andriy. "Linear and ellipsoidal pattern separation : theoretical aspects and experimental analysis." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/195011/.
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This thesis deals with a pattern classification problem, which geometrically implies data separation in some Euclidean feature space. The task is to infer a classifier (a separating surface) from a set or sequence of observations. This classifier would later be used to discern observations of different types. In this work, the classification problem is viewed from the perspective of the optimization theory: we suggest an optimization problem for the learning model and adapt optimization algorithms for this problem to solve the learning problem. The aim of this research is twofold, so this thesis can be split into two self-contained parts because it deals with two different type of classifiers each in a different learning setting. The first part deals with linear classification in the online learning setting and includes analysis of existing polynomial-time algorithms: the ellipsoid algorithm and the perceptron rescaling algorithm. We establish that they are based on different types of the same space dilation technique, and derive the parametric version of the latter algorithm, which allows to improve its complexity bound and exploit some extra information about the problem. We also interpret some results from the information-based complexity theory to the optimization model to suggest tight lower bounds on the learning complexity of this family of problems. To conclude this study, we experimentally test both algorithms on the positive semidefinite constraint satisfaction problem. Numerical results confirm our conjectures on the behaviour of the algorithms when the dimension of the problem grows. In the second part, we shift our focus from linear to ellipsoidal classifiers, which form a subset of second-order decision surfaces, and tackle a pattern separation problem with two concentric ellipsoids where the inner encloses one class (which is normally our class of interest, if we have one) and the outer excludes inputs of the other class(es). The classification problem leads to semidefinite program, which allows us to harness the efficient interior-point algorithms for solving it. This part includes analysis of the maximal separation ratio algorithm
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Mears, Paula Faye. "Managing Access during Employee Separation using Blockchain Technology." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703324/.
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On-boarding refers to bringing in an employee to a company and granting access to new hires. However, a person may go through different stages of employment, hold different jobs by the same employer and have different levels of information access during the employment duration. A shared services organization may have either limited or wide-spread access within certain groups. Off-boarding implies the removal of access of information or physical devices such as keys, computers or mobile devices when the employee leaves. Off-boarding is the management of the separation an employee from an institution. Many organizations use different steps that constitute the off-boarding process. Incomplete tracking of an employee's access is a security risk and can lead to unintended exposure of company information and assets.
Blockchain technology combines blocks of information together using a cryptographic algorithm based on the existing previous block and is verified by the peers in the blockchain network. This process creates an immutable record of employee system access providing an audit trail of access for any point in time to ensure that all access permissions can be removed once employment ends. This project proposes using blockchain technology to consolidate information across disparate groups, and to automate access removal to improve the employee off-boarding process.
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Bock, Christopher Paul. "Particle separation through Taylor-Couette flow and dielectrophoretic trapping." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4625.
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As the world population approaches seven billion, a greater strain is put on the resources necessary to sustain life. One of the most basic and essential resources is water and while two thirds of the earth is covered by water, the majority is either salt water (oceans and seas) or it is too contaminated to drink. The purpose of this project is to develop a portable device capable of testing whether a specific source of water (i.e. lake, river, well ...) is potable. There are numerous filtration techniques that can remove contaminants and make even the dirtiest water clean enough for consumption but they are for the most part, very time consuming and immobile processes. The device is not a means of water purification but rather focuses on determining the content of the water and whether it is safe. Particles within the water are separated and trapped using a combination of a Taylor Couette fluid flow system and Dielectrophoretic electrodes. This paper explores Taylor Couette flow in a large gap and low aspect ratio system through theory and experimentation with early stage prototypes. Different inner cylinder radii, 2.12cm, 1.665cm and 1.075cm, were tested at different speeds approaching, at and passing the critical Taylor number, 3825, 4713 and 6923 respectively for each cylinder. Dielectrophoretic (DEP) electrodes were designed, fabricated, coated and tested using latex beads to determine the method of integrating them within the fluid flow system. Taylor Couette theory, in terms of the formation of vortices within the large gap, small aspect ratio system, was not validated during testing. The flow pattern generated was more akin to a chaotic circular Couette flow but still served to move the particles toward the outer wall. Fully integrated tests were run with limited success.; Recommendations were made to pursue both circular Couette flow as the basis for particle separation and dimensional changes in the setup to allow for the formation of Taylor vortices by increasing the radius ratio but still allowing for a larger volume of fluid.ID: 028916599; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 108-109).
M.S.M.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Miniature Engineering Systems
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Kewley, Adam. "The synthesis and separation properties of organic cage compounds." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2010659/.
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Microporous materials play an important role in a variety of industrial and domestic applications. While a diverse range of microporous materials have been identified, this thesis focuses on porous organic cages (POCs) because they have received much attention as synthetically tunable, solution processable, microporous materials. After introducing the latest developments in POC synthesis and the general application of microporous materials as selective sorbents, this thesis presents three developments in organic cage chemistry: a high-throughput workflow for the discovery of POCs, which yielded a novel organic cage compound; the measurement of selective adsorption by POCs, wherein the first instance of chiral selectivity by a POC was recorded; and the first instance of applying POCs as stationary phases for gas chromatography, which produced columns that separate racemic mixtures, alkylaromatic isomers, and alkane isomers. Chapter 2, discovering novel organic cages, presents attempts to use high-throughput and in-silico techniques to accelerate the discovery of novel organic cages. These methods were utilised to isolate a novel organic cage, CCX-S, which is characterised and discussed. Chapter 3, organic cages as selective sorbents, presents the development of approaches for measuring selective adsorption. These methods were used to identify the first reported instance of enantioselective adsorption by an organic cage. Further measurements to explain this separation behavior are also presented. Chapter 4, chromatographic separations with organic cages, presents one method of practically leveraging the presented separation behavior. In Chapter 4, the coating of capillary columns with CC3 is presented. These columns were used to successfully perform gas chromatographic separations, the first recorded instance of using a POC to do so. The columns were further improved by modifying the coating method and using prefabricated CC3 nanoparticles. This modification enabled difficult separations to be performed using the column; for example, the separation of hexane’s five isomers.
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Morin, Sandrine. "A combined numerical and experimental study of aerofoil separation bubbles." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/47094/.
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