Дисертації з теми "Mass-transmission"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Mass-transmission.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Mass-transmission".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Antony, Joseph M. "Transmission characteristics of the quadrupole mass spectrometer." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3027712/.
Повний текст джерелаАнотація:
Advances in miniature and portable quadrupole mass spectrometry (QMS) have resulted in smaller instruments but often with reduced sensitivity, and this can restrict the applicability of portable MS for in-field applications. Sensitivity is influenced by the three-dimensional (3D) fringe field effects on the ion transmission characteristics of the Quadrupole Mass Filter (QMF). There is a requirement for a greater understanding of these effects. Particularly, the influence of the gap from the ion source to QMF entrance (source gap) on fringe field length, and its effects on ion transmission, are significant and little explored. The work presented in this thesis analyses the influence of fringe fields on ion transmission using a recently developed 3D QMF simulation model. In conjunction with simulations, experiments were carried out, using a single filter quadrupole mass spectrometer, to examine transmission characteristics across a range of common gases. To achieve this, an approach originally proposed by Ehlert was enhanced with a novel method for calibrating absolute transmission curve. Experimental results are compared with the predictions of the simulation model, which is used to study the significance of the source gap on fringe field effects. The effects of axial velocity in the fringing field region at the QMF entrance are also numerically simulated for multiple ion trajectories. The analysis of fringe fields shows a complex pattern of ion acceptance based on the initial ion entry conditions. The effect on ion transmission of the initial phase angle at which the ion is injected into the QMF has been shown to be of less importance than was predicted by the two-dimensional (2D) QMF model. Experimental measurements confirm a peaked transmission curve and agree well with the predictions of simulations. Different methods for determining fringe field length are discussed. Further analysis demonstrates the influence of the physical source gap length on both the length and intensity of the fringe field at the QMF entrance, and thereby ion transmission characteristics. For the first time, it is shown that, the source gap can be tailored for optimal transmission at the mass range of interest. Axial velocity perturbations are visualised in the fringe field region for different source gaps. The results presented are of importance to those within industry and academia working on the design of miniature and portable QMS targeting specific applications. The use of portable MS in the detection and monitoring of volatile organohalogens is demonstrated as an important environmental application. The wider significance of this work is that it allows QMS transmission efficiency (and hence instrument sensitivity) to be maximised for given instrument parameters and/or analytes (m/z values).
2
McClelland, Elizabeth A. "Heat and mass transfer in an axisymmetric sudden expansion." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/16462.
Повний текст джерела
3
Burn, David Joseph. "The mass-proper cycles of Henricus Isaac : genesis, transmission, and authenticity." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:cc90b91f-1666-4a9b-8cdd-47627ac670b5.
Повний текст джерелаАнотація:
This study reassesses the relationship between the monumental collection of Henricus Isaac's mass-proper cycles published as the Choralis Constantinus and the composer's original massproper projects. The first section charts changing views of Isaac as a historical figure, from his time to ours. Following this, the second section pursues the implications of recent redatings of major Choralis sources with a detailed investigation of the transmission of the Choralis' s music from composer to print. This analysis suggests new views for the make-up of each of the projects known to have been compiled together in the print: the earlier theory of a Constance Common of Saints is dismissed, whilst a mass-ordinary that may have belonged to the Constance project is identified; it is suggested that Isaac's mass-propers for the Imperial court cannot easily be seen as a single project, and that some anonymous propercycles not found in the Choralis may be Isaac's and may have belonged to Imperial repertory. To shed further light on the original scopes of Isaac's mass-proper projects, the third section of this thesis investigates Isaac's non-Choralis mass-propers. Particular attention is given to the large collection of such items found in two related manuscripts from latersixteenth- century Augsburg. Examination of the context and function of these manuscripts suggests that the unica they preserve attributed to Isaac are spurious. On the other hand, consideration of the Choralis's transmission and the shape of Isaac's secure Imperial repertory suggests that some anonymous cycles in the manuscript WeimB A are Isaac's. The final part of this study re-examines the attributions and de-attributions made in the first two sections at a music-stylistic level. No conflicting evidence is found. On the contrary, all earlier suggestions are reinforced.
4
Francis, Nicholas Donald. "Heat and mass transfer in a semi-porous textile composite." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17085.
Повний текст джерела
5
Macedone, Jeffrey Harris. "Ion Transmission in the first vacuum stage of an Inductively Coupled Plasma Mass Spectrometer." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/274.
Повний текст джерелаАнотація:
The inductively coupled plasma mass spectrometer (ICP-MS) is the instrument of choice for trace and ultra-trace elemental analysis. However, the ICP-MS suffers from matrix effects. Matrix effects occur when instrument response varies as the composition of the sample matrix is changed. Matrix effects, or non-spectroscopic interferences, limit the accuracy of routine analysis. Identification of the sources of matrix effects provide a basis for reducing or eliminating them. As inaccuracies in the ICP-MS are more severe than those in the ICP atomic emission spectrometer, the problem may be due, at least in part, to the vacuum interface used to couple the plasma source and mass spectrometer. The research herein is a study of matrix effect sources in the first stage of the vacuum interface. This study utilized laser-induced fluorescence of atomic species to identify factors affecting analyte transport through the sampling orifice of the vacuum interface. Several non-idealities in the performance of the interface were found. (1) Operating conditions and sample compositions can negatively affect the efficiency with which ions are extracted through the vacuum interface coupling the plasma source to the mass spectrometer. (2) The sampling cone itself was found to suppress and narrow ion distributions in the plasma. (3) Changes in the degree of ionization were identified in the first vacuum stage. The evidence of recombination and state-changing collisions was observed in the first vacuum stage at lower power settings. Matrix effects occur in the first vacuum stage, the first step of the ion extraction process. This work shows that changes in ion transport through the first vacuum stage of the vacuum interface of an ICP-MS affect the overall performance of the instrument.
6
Eghbali, Davoud A. "Combined heat and mass transfer in gas-liquid two-phase systems." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17867.
Повний текст джерела
7
Williamson, Nicholas J. "Numerical modelling of heat and mass transfer and optimisation of a natural draft wet cooling tower." University of Sydney, 2007. http://hdl.handle.net/2123/4123.
Повний текст джерелаАнотація:
Doctor of PhilosophyThe main contribution of this work is to answer several important questions relating to natural draft wet cooling tower (NDWCT) modelling, design and optimisation. Specifically, the work aims to conduct a detailed analysis of the heat and mass transfer processes in a NDWCT, to determine how significant the radial non-uniformity of heat and mass transfer across a NDWCT is, what the underlying causes of the non-uniformity are and how these influence tower performance. Secondly, the work aims to determine what are the consequences of this non-uniformity for the traditional one dimensional design methods, which neglect any two-dimensional air flow or heat transfer effects. Finally, in the context of radial non-uniformity of heat and mass transfer, this work aims to determine the optimal arrangement of fill depth and water distribution across a NDWCT and to quantify the improvement in tower performance using this non-uniform distribution. To this end, an axisymmetric numerical model of a NDWCT has been developed. A study was conducted testing the influence of key design and operating parameters. The results show that in most cases the air flow is quite uniform across the tower due to the significant flow restriction through the fill and spray zone regions. There can be considerable radial non-uniformity of heat transfer and water outlet temperature in spite of this. This is largely due to the cooling load in the rain zone and the radial air flow there. High radial non-uniformity of heat transfer can be expected when the cooling load in the rain zone is high. Such a situation can arise with small droplet sizes, low fill depths, high water flow rates. The results show that the effect of tower inlet height on radial non-uniformity is surprisingly very small. Of the parameters considered the water mass flow rate and droplet size and droplet distribution in the rain zone have the most influence on radial noniv uniformity of heat transfer. The predictions of the axisymmetric numerical model have been compared with a one dimensional NDWCT model. The difference between the predictions of tower cooling range is very low, generally around 1-2%. This extraordinarily close comparison supports the assumptions of one dimensional flow and bulk averaged heat transfer implicit in these models. Under the range of parameters tested here the difference between the CFD models predictions and those of the one dimensional models remained fairly constant suggesting that there is no particular area where the flow/heat transfer becomes so skewed or non-uniform that the one dimensional model predictions begin to fail. An extended one dimensional model, with semi-two dimensional capability, has been developed for use with an evolutionary optimisation algorithm. The two dimensional characteristics are represented through a radial profile of the air enthalpy at the fill inlet which has been derived from the CFD results. The resulting optimal shape redistributes the fill volume from the tower centre to the outer regions near the tower inlet. The water flow rate is also increased here as expected, to balance the cooling load across the tower, making use of the cooler air near the inlet. The improvement has been shown to be very small however. The work demonstrates that, contrary to common belief, the potential improvement from multi-dimensional optimisation is actually quite small.
8
Macedone, Jeffrey Harris. "Ion transmission studies in the first vacuum stage of an inductively coupled plasma mass spectrometer /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd785.pdf.
Повний текст джерела
9
Munir, Shahid Uraiwan Kanungsukkasem. "Inpact mass media on the knowledge of HIV/AIDS transmission among ever married women of Pakistan /." Abstract, 2006. http://mulinet3.li.mahidol.ac.th/thesis/2549/cd393/4838765.pdf.
Повний текст джерела
10
Ali, Muhammad Atif Uraiwan Kanungsukkasem. "Association between mass media and HIV transmission knowledge of ever-married women in Pakistan : a formative study /." Abstract, 2007. http://mulinet3.li.mahidol.ac.th/thesis/2550/cd405/4938538.pdf.
Повний текст джерела
11
Khan, Md Mahfujul H. "Understanding Impact Load Wave Transmission Performance of Elastic Metamaterials." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479146177020136.
Повний текст джерела
12
Olanrewaju, Anuoluwapo Mary. "Analysis of boundary layer flow of nanofluid with the characteristics of heat and mass transfer." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2157.
Повний текст джерелаАнотація:
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011.Nanofluid, which was first discovered by the Argonne laboratory, is a nanotechnology- based heat transfer fluid. This fluid consists of particles which are suspended inside conventional heat transfer liquid or base fluid. The purpose of this suspension is for enhancing thermal conductivity and convective heat transfer performance of this base fluid. The name nanofluid came about as a result of the nanometer- sized particles of typical length scales 1-100nm which are stably suspended inside of the base fluids. These nanoparticles are of both physical and chemical classes and are also produced by either the physical process or the chemical process. Nanofluid has been discovered to be the best option towards accomplishing the enhancement of heat transfer through fluids in different unlimited conditions as well as reduction in the thermal resistance by heat transfer liquids. Various manufacturing industries and engineering processes such as transportation, electronics, food, medical, textile, oil and gas, chemical, drinks e.t.c, now aim at the use of this heat transfer enhancement fluid. Advantages such organisations can obtain from this fluid includes, reduced capital cost, reduction in size of heat transfer system and improvement of energy efficiencies. This research has been able to solve numerically, using Maple 12 which uses a fourth- fifth order Runge -kutta- Fehlberg algorithm alongside shooting method, a set of nonlinear coupled differential equations together with their boundary conditions, thereby modelling the heat and mass transfer characteristics of the boundary layer flow of the nanofluids. Important properties of these nanofluids which were considered are viscosity, thermal conductivity, density, specific heat and heat transfer coefficients and microstructures (particle shape, volume concentration, particle size, distribution of particle, component properties and matrixparticle interface). Basic fluid dynamics equations such as the continuity equation, linear momentum equation, energy equation and chemical species concentration equations have also been employed.
13
Jalil, Nawal Aswan Abdul. "Transmission of vibration through backrests and apparent mass of the back during whole-body fore-and-aft vibration." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427371.
Повний текст джерела
14
Hashi, Hassina Abdullahi. "Effectiveness of mass drug administration for reducing seasonal malaria transmission towards its elimination in hotspot areas in Zanzibar." Thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-326636.
Повний текст джерелаАнотація:
Background: Following the increase of international funding for implementation of the combined effective malaria control strategies for prevention, diagnosis and treatment in the past decades, a significant reduction with 30% of malaria attributed morbidity and mortality has been achieved. At present, declining transmission intensities, in areas of successful malaria control, have resulted in a relative increase of asymptomatic low parasite density infections that fall below the detection level of rapid diagnostic tests and microscopy. Mass drug administration (MDA) is a treatment of the entire population in a geographic area with antimalarial drugs irrespective of the presence of symptoms and without diagnostic testing, with the purpose of targeting asymptomatic malarial infections. Aim: The overall purpose of this study is to determine the effectiveness of two rounds of MDA for reducing malaria transmission on Unguja island in Zanzibar. Methods: A cluster-randomised controlled study with two arms was performed: an arm with two rounds of MDA, and a control arm without MDA. A total of 7941 field samples from the first MDA round and 9853 samples four months after the second round of MDA were screened. Two different sets of qPCRs, 18Sq-PCR and cytb-qPCR were used to detect the positivity of Plasmodium infection. The species were further identified using restriction fragment length polymorphism (RFLP). Results: Cytb-qPCR detected more positive samples compared to 18S-qPCR. The qPCR determined malaria prevalence six months after the second MDA round was 1.7%. P. falciparum was the predominant species accounting for 64.6% and 63.3% from first MDA round and four month after second round of MDA respectively. From the first MDA round, the prevalence of P. malariae and P. vivax was 15.4% with 0.6% respectively. The parasite prevalence in the second round of MDA was: 10.8 % in P. malariae, 7.2 % in P. ovale and 0.6 % in P. vivax. Conclusion: There is still a presence of asymptomatic low-density parasite carriers and the parasite prevalence remains relatively low in Zanzibar. MDA can be effective in low endemic settings when the goal is elimination.
15
Subramaniam, Vishwanath. "Computational analysis of binary-fluid heat and mass transfer in falling films and droplets." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26485.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Garimella, Srinivas; Committee Member: Fuller, Tom; Committee Member: Jeter, Sheldon; Committee Member: Lieuwen, Tim; Committee Member: Wepfer, William. Part of the SMARTech Electronic Thesis and Dissertation Collection.
16
Widaman, Jean. "The mass ordinary settings of Arnold de Lantins : a case study in the transmission of early fifteenth-century music /." Ann Arbor (Mich.) : UMI, 2006. http://catalogue.bnf.fr/ark:/12148/cb40063706f.
Повний текст джерела
17
Shao, Ming. "Modelling simultaneous heat and mass transfer in wood." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42073.
Повний текст джерелаАнотація:
The fundamental and quantitative study of heat and mass transfer processes in wood plays an important role for understanding many important production processes, such as wood drying and hot-pressing. It will help us improve the existing products and production techniques and develop new manufacturing technology. The most difficult aspect of the study is the complicated interactions of heat and mass transfer mechanisms. Extensive characterization of these physical processes using a strictly experimental approach is extremely difficult because of the excessively large number of variables that must be considered. However, mathematical modeling and numerical techniques serve as a powerful tool to help us understand the complicated physical processes.
The goal of this research is to model the simultaneous heat and mass transfer in wood. The specific objectives of this research are:
1) develop a computer simulation program, implementing an existing one-dimensional mathematical drying model, using a finite difference approach, to numerically evaluate the mathematical model.
2) study sensitivity of the heat and mass transfer model to determine the effects of wood physical properties and environmental conditions on the drying processes.Master of Science
18
Nagavarapu, Ananda Krishna. "Binary fluid heat and mass exchange at the microscale in internal and external ammonia-water absorption." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45777.
Повний текст джерелаАнотація:
Absorption space-conditioning systems are environmentally benign alternatives to vapor compression systems and have the capability of being driven by waste heat. However, a lack of practically feasible and economically viable compact heat and mass exchangers is a major limitation in the success of this technology. The viability of the absorption cycle depends upon the performance of the absorber, which experiences large heat and mass transfer resistances due to adverse temperature and concentration gradients during the phase change of the binary mixture working fluid, resulting in large overall component sizes. Understanding of the coupled heat and mass transfer during binary fluid mixture absorption at the microscales is critical for the miniaturization of these components, which will enable broad implementation of this technology.
The proposed study aims to achieve this by investigating ammonia-water absorption for two distinct flow configurations: external falling films and internal convective flows. For the falling-film absorption case, ammonia-water solution flows around an array of small diameter coolant tubes while absorbing vapor. This absorber is installed in a test facility comprising all components of a single-effect absorption chiller to provide realistic operating conditions at the absorber. Local temperature, pressure, and flow measurements will be taken over a wide range of operating conditions and analyzed to develop a heat and mass transfer model for falling-film ammonia-water absorption. A microscale convective flow absorber will also be investigated. This absorber consists of an array of parallel, aligned alternating shims with integral microscale features, enclosed between cover plates. These microscale features facilitate flow of various fluid streams and the associated heat and mass transfer. The use of microchannels induces high heat and mass transfer rates without any active or passive surface enhancement. The microscale absorber for small-scale applications will be evaluated over a wide range of operating conditions on a single-effect absorption heat pump breadboard test facility. The study will conclude with a comparison of the two flow configurations for absorption, with recommendations for their application in future miniaturization efforts
19
Erhard, Moritz Gérard [Verfasser], and G. [Akademischer Betreuer] Drexlin. "Influence of the magnetic field on the transmission characteristics and the neutrino mass systematic of the KATRIN experiment / Moritz Gérard Erhard ; Betreuer: G. Drexlin." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1124902902/34.
Повний текст джерела
20
Boomhower, Daniel F. "The Manuscript Transmission of J. S. Bach's Mass in B Minor (BWV 232) and the Development of the Concept of Textual Authority, 1750-1850." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1489155807416477.
Повний текст джерела
21
Srinivasan, Raghavan. "CFD Heat Transfer Simulation of the Human Upper Respiratory Tract for Oronasal Breathing Condition." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29310.
Повний текст джерелаАнотація:
In this thesis. a three dimensional heat transfer model of heated airflow through the upper human respiratory tract consisting of nasal, oral, trachea, and the first two generations of bronchi is developed using computational fluid dynamics simulation software. Various studies have been carried out in the literature investigating the heat and mass transfer characteristics in the upper human respiratory tract, and the study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage based on level of exposure. The model considered is for the simultaneous oronasal breathing during the inspiration phase with high volumetric flow rate of 90/liters minute and a surrounding air temperature of 100 degrees centigrade. The study of the heat and mass transfer, aerosol deposition and flow characteristics in the upper human respiratory tract using computational fluid mechanics simulation requires access to a two dimensional or three dimensional model for the human respiratory tract. Depicting an exact model is a complex task since it involves the prolonged use of imaging devices on the human body. Hence a three dimensional geometric representation of the human upper respiratory tract is developed consisting of nasal cavity, oral cavity, nasopharynx, pharynx, oropharynx, trachea and first two generations of the bronchi. The respiratory tract is modeled circular in cross-section and varying diameter for various portions as identified in this study. The dimensions are referenced from the literature herein. Based on the dimensions, a simplified model representing the human upper respiratory tract is generated.This model will be useful in studying the flow characteristics and could assist in treatment of injuries to the human respiratory tract as well as help optimize drug delivery mechanism and dosages. Also a methodology is proposed to measure the characteristic dimension of the human nasal and oral cavity at the inlet/outlet points which are classified as internal measurements.
22
Yasnou, Viktar. "Development and improvement of the experimental techniques for fluid examination." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209175.
Повний текст джерелаАнотація:
The aim of the thesis is the development and improvement of the experimental techniques for fluid examination. The thesis consists of two parts and both examine heat and mass transfer in liquids using the optical methods and thermal analysis. The first part deals with the measurement techniques for studying flow patterns and their stability in systems with gas/liquid interface, in particular, in a liquid bridge system. The second part is aimed at the improvement of the existing experimental techniques to study the heat/mass transfer in the mixtures with Soret effect, enclosed in a container.Part A is motivated by preparation of the experiment JEREMI (The Japanese-European Research Experiment on Marangoni Instability) to be performed on the International Space Station (ISS). One of the objectives of the experiment is the control of the threshold of an oscillatory flow in the liquid zone by the temperature and velocity of the ambient gas. The developed set-up for a liquid bridge allows to blow gas parallel to the interface at different temperatures and investigate the effects of viscous and thermal stresses on the stability of the flow. The present study reports on isothermal experiments with moving gas and non-isothermal experiments with motionless gas when the cooling of the interface occurs due to evaporation. The discussion concerning the experimental observations is based on two sources: an interface shape measured optically and the records on thermocouples giving an indication of how temperature and frequency evolve over time.
Part B is related to ground-based studies in course of preparation and realization of the microgravity experiment DCMIX (Diffusion Coefficient in MIXtures). DCMIX project is a series of experiments aimed at measuring of the Soret coefficients in liquid mixtures on the ISS which involves a wide international group of scientists. Two experiments have been recently completed and the third one is under preparation In the course of this thesis all the aspects of the previously existing set-up for measurements of the Soret (thermal diffusion) and diffusion coefficients in binary mixtures were studied, uncertainties were identified and improvements were done to obtain reliable results. The final design has been validated by measuring coefficients in three binary benchmark mixtures and water-isopropanol. The obtained results agree well with literature data.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
23
Fearn, Sarah. "A SIMS based bevel-image technique for the analysis of semiconductor materials." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312125.
Повний текст джерела
24
Beaulieu, Patricia. "Flammability Characteristics at Heat Fluxes up to 200 kW/m2 and The Effect of Oxygen on Flame Heat Flux." Digital WPI, 2005. https://digitalcommons.wpi.edu/etd-dissertations/427.
Повний текст джерелаАнотація:
"This dissertation documents two interrelated studies that were conducted to more fundamentally understand the scalability of flame heat flux. The first study used an applied heat flux in the bench scale horizontal orientation which simulates a large scale flame heat flux. The second study used enhanced ambient oxygen to actually increase the bench scale flame heat flux itself. Understanding the scalability of flame heat flux more fully will allow better ignition and combustion models to be developed as well as improved test methods. The key aspect of the first study was the use of real scale applied heat flux up to 200 kW/m2. An unexpected non-linear trend is observed in the typical plotting methods currently used in fire protection engineering for ignition and mass loss flux data for several materials tested. This non-linearity is a true material response. This study shows that viewing ignition as an inert material process is inaccurate at predicting the surface temperature at higher heat fluxes and suggests that decomposition kinetics at the surface and possibly even in-depth may need to be included in an analysis of the process of ignition. This study also shows that viewing burning strictly as a surface process where the decomposition kinetics is lumped into the heat of gasification may be inaccurate and the energy balance is too simplified to represent the physics occurring. The key aspect of the second study was direct experimental measurements of flame heat flux back to the burning surface for 20.9 to 40 % ambient oxygen concentrations. The total flame heat flux in enhanced ambient oxygen does not simulate large scale flame heat flux in the horizontal orientation. The vertical orientation shows that enhanced ambient oxygen increases the flame heat flux more significantly and also increases the measured flame spread velocity."
25
Psimas, Michael J. "Experimental and numerical investigation of heat and mass transfer due to pulse combustor jet impingement." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33863.
Повний текст джерелаАнотація:
Under certain circumstances pulse combustors have been shown to improve both heat transfer and drying rate when compared to steady flow impingement. Despite this potential, there have been few investigations into the use of pulse combustor driven impingement jets for industrial drying applications. The research presented here utilized experimental and numerical techniques to study the heat transfer characteristics of these types of oscillating jets when impinging on solid surfaces and the heat and mass transfer when drying porous media. The numerical methods were extensively validated using laboratory heat flux and drying data, as well as correlations from literature. As a result, the numerical techniques and methods that were developed and employed in this work were found to be well suited for the current application. It was found that the pulsating flows yielded elevated heat and mass transfer compared to similar steady flow jets. However, the numerical simulations were used to analyze not just the heat flux or drying, but also the details of the fluid flow in the impingement zone that resulted in said heat and mass transport. It was found that the key mechanisms of the enhanced transfer were the vortices produced by the oscillating flow. The characteristics of these vortices such as the size, strength, location, duration, and temperature, determined the extent of the improvement. The effects of five parameters were studied: the velocity amplitude ratio, oscillation frequency, the time-averaged bulk fluid velocity at the tailpipe exit, the hydraulic diameter of the tailpipe, and the impingement surface velocity. Analysis of the resulting fluid flow revealed three distinct flow types as characterized by the vortices in the impingement zone, each with unique heat transfer characteristics. These flow types were: a single strong vortex that dissipated before the start of the next oscillation cycle, a single persistent vortex that remained relatively strong at the end of the cycle, and a strong primary vortex coupled with a short-lived, weaker secondary vortex. It was found that the range over which each flow type was observed could be classified into distinct flow regimes. The secondary vortex and persistent vortex regimes were found to enhance heat transfer. Subsequently, transition criteria dividing these regimes were formed based on dimensionless parameters. The critical dimensionless parameters appeared to be the Strouhal number, a modified Strouhal number, the Reynolds number, the velocity amplitude ratio, and the H/Dh ratio. Further study would be required to determine if these parameters offer similar significance for other configurations.
26
Singla, Minni [Verfasser], Peter [Akademischer Betreuer] Senger, and Joachim [Akademischer Betreuer] Stroth. "The Silicon Tracking System of the CBM experiment at FAIR : development of microstrip sensors and signal transmission lines for a low-mass, low-noise system / Minni Singla. Gutachter: Peter Senger ; Joachim Stroth." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2014. http://d-nb.info/1048091422/34.
Повний текст джерела
27
De, Luca Anthony. "Redistribution atomique de contaminants métalliques aux interfaces des structures des technologies CMOS." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4302/document.
Повний текст джерелаАнотація:
Au cours de ces travaux de thèse, nous avons étudié la redistribution atomique de contaminantsmétalliques dans le silicium et au voisinage d'une interface SiO2/Si. Pour mener à bien cetteétude, trois techniques de caractérisation complémentaires ont été utilisées (TEM,APT,SIMS).Nous avons dans un premier temps étudié la diffusion ainsi que la ségrégation d'équilibre de contaminants à une interface SiO2/Si, et plus particulièrement, la diffusion du W et du Mo. Le Wprésente une cinétique de diffusion extrêmement lente. Les caractérisations réalisées par TEM et APT nous ont permis de discuter les profils de concentrations mesurés par SIMS et nous ont guidés dans le choix du modèle de diffusion proposé. L'étude de la diffusion du Mo révéle que cette espèce présente une limite de solubilité faible dans le silicium et une forte interaction avec des défauts d'irradiation, provoquant sa précipitation.Dans un second volet, nous nous sommes intéressés à l'effet d'une interface mobile, lors d'une réaction, sur la redistribution atomique des contaminants proches de cette interface. Nous avons ainsiréalisé une étude comparative des comportements du Fe et W lors de procédés d'oxydation.Le tungstène précipite dans le volume et est progressivement rejeté par l'oxydation. Le ferprécipite à l'interface SiO2/Si, provoquant un effet de masquage dont nous avons montré qu'il étaitresponsable de la formation de défauts pyramidaux d'interface, caractéristiques d'une contaminationen fer du silicium. Le procédé de germano-siliciuration de nickel, réalisé à basses températures a également été investigué. Cette réaction provoque le rejet 3D du germanium à l'interface NiSiGe/SiGeDuring this thesis work, we studied the atomic redistribution of metallic contaminantsin silicon and near a SiO2/Si interface. To conduct this study, we used three complementary characterisation techniques : transmission electron microscopy (TEM), atomic probe tomography (APT) and secondary ion mass spectrometry (SIMS).We first studied the diffusion and equilibrium segregation of various contaminants at a SiO2/Si interface, and more particularly, the diffusion of W and Mo. W exhibits a very slow diffusion kinetic.Physico-chemical characterizations performed by TEM and APT allowed discussing the concentrationprofiles obtained by SIMS leading to the diffusion model that we proposed. The study of Mo diffusionrevealed that this specy exhibits a low solubility limit in silicon and strongly interacts with irradiation-induced defects, leading to its precipitation.In a second phase, we studied the effect of a mobile interface, during a reaction, on the atomic redistribution of contaminants near this interface. We performed a comparative study of the behaviourof Fe and W during oxidation processes. W precipitates in the silicon substrate and is progressivelyrejected (snowplow) by the oxidation. Fe preferentially precipitates at the SiO2/Si interface. Theseprecipitates mask a part of the silicon substrate and thus hinder its oxidation, leading to the formation of characteristics pyramidal-shaped defects at the interface. Low temperature nickel germano-silicide formation have also been investigated. This reaction leads to the 3D snowplow of germanium atoms at the NiSiGe/SiGe interface
28
Ropelato, Karolline. "Transferencia de calor e massa em colunas de destilação a vacuo : uma abordagem Euleriana-Lagrangeana." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266395.
Повний текст джерелаАнотація:
Orientadores: Milton Mori, Washington de Oliveira GeraldelliTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-12T14:06:37Z (GMT). No. of bitstreams: 1 Ropelato_Karolline_D.pdf: 2250629 bytes, checksum: 15568f3eff580c49e2a6e20cc69a4f04 (MD5) Previous issue date: 2008
Resumo: A compreensão dos fenômenos existentes em equipamentos industriais é de extrema importância para o seu projeto e otimização. O uso de colunas de destilação é conhecido antes mesmo do século XX. Desde o seu surgimento até os tempos atuais, significativos avanços ocorreram. A literatura apresenta diversos trabalhos considerando o estudo de colunas de destilação com pratos ou recheios. No entanto, pouca atenção tem sido dada para colunas com vazios. O presente trabalho apresenta uma metodologia para o estudo da transferência de calor e massa em colunas de destilação com distribuidores do tipo sprays em processos de destilação, considerando uma abordagem Euleriana-Lagrangeana. Neste tipo de abordagem, as gotas são modeladas individualmente a partir de trajetórias na fase contínua. O modelo k-e ?foi empregado para predizer o comportamento da fase vapor. O equilíbrio termodinâmico é modelado considerando a lei de Raoult. Utilizando conjuntamente conhecimentos de Termodinâmica, Processos de Separação (destilação) e de Fluidodinâmica Computacional (CFD), um modelo matemático é proposto. A aplicação das escalas características de tempo como metodologia de análise e compreensão dos resultados é proposta.
Abstract: The understanding of fluid dynamic phenomena in industrial equipments are extremely important for new projects and their optimization. Distillation columns are being used even before the XX century. Since that time many advances have happened. The literature presents different studies as far as plates or packed columns are concerned, but few attention have been done in empty section. The present study shows a methodology to study the heat and mass transfer in empty sections of distillation columns considering the Eulerian-Lagrangian approach. The Lagrangian tracking for the liquid droplets was used to predict spray distribution. The model takes into account the influence of the liquid flow within the vapor phase flow. The k-e turbulence model was applied to predict the vapor behavior. The thermodynamic equilibrium considered the Raoult's Law. Considering the different areas as thermodynamics, Separation Process (distillation) and the Computational Fluid Dynamics (CFD), a mathematical model is proposed. The time scales methodology is important as a feature to analyze and understanding the results.
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
29
Mitra, Biswajit. "Supercritical gas cooling and condensation of refrigerant R410A at near-critical pressures." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06142005-232427/.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Garimella, Srinivas, Committee Chair ; Ghiaasiaan, S. Mostafa, Committee Member ; Graham, Samuel, Committee Member ; Breedveld, Victor, Committee Member ; Fuller,Tom, Committee Member.
30
Малахов, Дмитро Сергійович. "Зміцнення поверхні сплаву АМг6 комбінованою високоенергетичною обробкою". Master's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/41423.
Повний текст джерелаАнотація:
Об’єкт дослідження – фізико-хімічні процеси, які відбуваються внаслідок електроіскрового легування титаном, вольфрамом, міддю та ультразвуковою ударною обробкою поверхні алюмінієвого сплаву АМг6. Мета роботи – синтез композиційних покриттів на поверхні сплаву АМг6 електроіскровим легуванням Ti, W та Сu з подальшою ультразвуковою ударною обробкою. Методи дослідження – мікродюрометричний, рентгеноструктурний та мікрорентгеноспектральний аналіз, просвічувальна електронна мікроскопія, а також випробування на корозійну стійкість. Практичне значення – одержані в роботі наукові результати представляють практичний інтерес для машинобудування та авіаційної галузі. Результати досліджень – запропоновано ефективний спосіб зміцнення поверхневого шару алюмінієвого сплаву АМг6 за допомогою комбінованої обробки – ЕІЛ та УЗУО. Електроіскрове легування сприяє зміцненню поверхні за рахунок утворення в приповерхневому шарі товщиною до 25 мкм інтерметалідних фаз – Al3Ti, Al18Ti2Mg3, Al12W, Al5W, Аl2Cu та Al6Mg4Cu. Ультразвукова ударна обробка обумовлює диспергування субзеренної/зеренної структури, підвищує твердість на 70-80 % та сприяє інтенсифікації масопереносу легуючого елементу. Результатом комбінованої обробки є підвищення мікротвердості (до 3,5 разів) та корозійної стійкості поверхневих шарів сплаву АМг6 у порівнянні з вихідним станомThe object of research - physico-chemical processes that occur as a result of electrospark doping with titanium, tungsten, copper and ultrasonic shock treatment of the surface of the aluminum alloy AMg6. The purpose of the work is the synthesis of composite coatings on the surface of AMg6 alloy by electrospark doping of Ti, W or Cu with subsequent ultrasonic shock treatment. Research methods - microdiurometric, X-ray structural and micro-X-ray spectral analysis, transmission electron microscopy, as well as tests for corrosion resistance. Practical significance - the scientific results obtained in this work are of practical interest for the mechanical engineering and aviation industries. Research results - an effective way to strengthen the surface layer of aluminum alloy AMg6 using a combine processing - EDA and UIT. Electrospark doping helps to strengthen the surface due to the formation of intermetallic phases - Al3Ti, Al18Ti2Mg3, Al12W, Al5W, Al2Cu and Al6Mg4Cu in the near-surface layer up to 25 μm thick. Ultrasonic shock treatment determines the dispersion of the subgrain / grain structure, increases the hardness by 70-80 % and enhances the mass transfer of the alloying element. The result of the combined treatment is an increase in microhardness (up to 3.5 times) and corrosion resistance of the surface layers of the AMg6 alloy compared to the initial state.
31
Малахов, Дмитро Сергійович. "Зміцнення поверхні сплаву АМг6 електроіскровим легуванням Cu та ультразвуковою ударною обробкою". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/29191.
Повний текст джерелаАнотація:
Об’єкт дослідження – фізико-хімічні процеси, які відбуваються внасідок електроіскрового легування міддю та ультразвукової ударної обробки поверхні алюмінієвого сплаву АМг6.
Мета роботи – синтез композиційних покриттів на поверхні сплаву АМг6 електроіскровим легуванням Сu з подальшою ультразвуковою ударною обробкою.
Методи дослідження – мікродюрометричний, рентгеноструктурний та мікрорентгеноспектральний аналіз, просвічувальна електронна мікроскопія, а також випробування на корозійну стійкість.
Практичне значення – одержані в роботі наукові результати представляють практичний інтерес для машинобудування та авіаційної галузі.
Результати досліджень – запропоновано ефективний спосіб зміцнення поверхневого шару алюмінієвого сплаву АМг6 за допомогою комбінованоїобробки – ЕІЛ та УЗУО. Електроіскрове легування мідним електродом сприяє зміцненню поверхні за рахунок утворення в приповерхневому шарі товщиною до 25 мкм інтерметалідних фаз – Аl2Cu та Al6Mg4Cu. Ультразвукова ударна обробка обумовлює диспергування субзеренної/зеренної структури, підвищує твердість на 70-80% та сприяє інтенсифікації масопереносу легуючого елементу. Результатом комбінованої обробки є підвищення мікротвердості (в 3,5 рази) та корозійної стійкості поверхневих шарів сплаву АМг6 у порівнянні з вихідним станом.The object of research is the physical and chemical processes that take place near the electrosurgical doping of copper and ultrasonic shock treatment of the surface of aluminium alloy AMg6. The purpose of the work is the synthesis of composite coatings on the surface of AMg alloy by the electrospray doping of Cu followed by ultrasonic shock treatment. Methods of research - microdyrometric, X-ray and micro-ray diffraction analysis, transdermal electron microscopy, as well as corrosion resistance tests. Practical significance - the scientific results obtained in the work are of practical interest to the mechanical engineering and aviation industry. The results of the research - an effective way to strengthen the surface layer of aluminium alloy AMg6 with the help of combined processing - EIL and UIT. Electrospray doping with copper electrode helps to strengthen the surface due to the formation in the near-surface layer up to 25 microns of intermetallic phases - Al2Cu and Al6Mg4Cu. Ultrasonic shock treatment causes the dispersion of the sub-grains / grain structure, increases the hardness by 70-80 % and promotes the intensification of the mass transfer of the alloying element. The result of the combined treatment is an increase in microhardness (3,5 times) and corrosion resistance of the surface layers of AMg6 alloy as compared to the initial state.
32
Chavy, Agathe Corinne. "Influence de l'environnement sur le cycle de transmission de la leishmaniose cutanée en Guyane, à multi-échelle spatiale Ecological niche modelling for predicting the risk of cutaneous leishmaniasis in the Neotropical moist forest biome Identification of French Guiana sand flies using MALDI-TOF mass spectrometry with a new mass spectra library « Regional scale ecological drivers of sandfly communities in French Guiana." Thesis, Guyane, 2019. http://www.theses.fr/2019YANE0013.
Повний текст джерелаАнотація:
Les cycles de transmission des maladies zoonotiques et les facteurs qui les influencent sont difficiles à déterminer, particulièrement lorsqu’ils sont dus à des agents pathogènes généralistes dépendant de plusieurs espèces hôtes et vectrices pour être transmis. De plus, perturbations anthropiques et changements climatiques exercent de fortes pressions sur les systèmes hôtes-pathogène-vecteurs pouvant modifier les cycles de transmission. Une approche globale à différentes échelles spatiales est alors nécessaire pour caractériser et quantifier l’importance relative de ses facteurs. Cette approche a été utilisée pour étudier l’écologie du cycle de transmission de la leishmaniose cutanée (LC) en Guyane, une maladie vectorielle sylvatique avec de multiples hôtes et vecteurs. Ce cycle, soumis à des pressions anthropiques grandissantes, a vu sa dynamique se modifier, ce qui a entrainé une augmentation du risque de transmission aux populations humaines. Dans cette thèse, nous avons étudié l’influence des facteurs environnementaux, climatiques et anthropiques, à l’échelle globale du biome amazonien et régionale de la Guyane sur la distribution des cas humains de LC, en utilisant des modèles de niches écologiques. Puis, grâce à l’utilisation du séquençage à haut débit et d’outils probabilistes, nous avons observé la réponse des communautés de vecteurs à une échelle régionale dans des sites forestiers soumis à différents degrés de perturbation. Enfin, nous avons contribué à l’amélioration de la gamme d’outils disponibles pour l’identification des phlébotomes en utilisant le MALDI-TOF MS. Cette thèse a permis d’améliorer les connaissances générales du cycle de la LC en GuyaneFor many zoonotic diseases, transmission cycles remain difficult to determine, especially when they are due to generalist pathogens that can rely on several host and vector species to be transmitted. In addition, anthropogenic disturbances and climate change have strong impacts on ecosystems and can alter pathogen transmission cycles. Characterization and quantification of the relative importance of factors influencing host-pathogen-vector systems is then central for a global approach aiming to understand pathogen dynamics at different spatial scales. This approach has been used to study the ecology of the transmission cycle of cutaneous leishmaniasis (CL) in French Guiana. This vector-born disease, mainly sylvatic and including multiple hosts and vectors, is influenced by strong anthropic pressures that modified the dynamics of the cycle and led to an increase in the risk of transmission to human populations. In this work, we first explored the influence of environmental, climatic and anthropic factors on the distribution of human cases of CL at the global scale of the Amazonian biome and at the regional scale of French Guiana, using ecological niche modelling, allowing building risk maps. Then we observed the responses of communities of sandflies and known vectors at the regional scale in forest sites facing different disturbance levels. This work was made possible using a metabarcoding approach with high throughput sequencing. Last, we contributed to the improvement of the range of tools available for the identification of sandflies using the MALDI-TOF MS. This thesis contributed to the improvement of the general knowledge of the CL cycle in French Guiana
33
Laroche, Maureen. "Application d'outils innovants de génomique et protéomique à l'entomologie médicale." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0665.
Повний текст джерелаАнотація:
Les maladies transmises par les arthropodes vecteurs sont responsables de centaines de milliers de cas d’infections humaines et de décès chaque année à travers le monde. Ces maladies, causées par des bactéries, virus ou parasites, parfois émergents ou réémergents, sont parfois peu connues ou sous-estimées. Les arthropodes peuvent être utilisés comme outil de suivi épidémiologique des micro-organismes qui leur sont associés et dont certains pourront être transmis à des hôtes vertébrés. L’identification des arthropodes reste cruciale dans les enquêtes entomologiques.Nous avons pu ainsi détecter de potentielles nouvelles bactéries dans les tiques de Tahiti et les triatomes de Guyane.Nous avons exploré le microbiote salivaire de près de mille moustiques de 3 pays différents par métagénomique 16S. Nous avons ainsi détecté un large nombre de bactéries pathogènes opportunistes mais aussi un très grand nombre de génotypes correspondant probablement à des espèces et genres bactériens nouveaux. Enfin notre axe majeur a été le développement de l’utilisation de la spectrométrie de masse MALDI-TOF en entomologie médicale. Pour pallier les limites des méthodes de référence d’identification des arthropodes existantes, nous avons validé l’utilisation de cet outil pour l’identification des moustiques (collectés sur terrain en Australie) et de puces (Espagne, Corse, Algérie). Nous avons également mis au point son utilisation pour l’identification de nouvelles familles d’arthropodes, comme les punaises de lits et les triatomes. Nous avons pu mettre en évidence, la capacité de la spectrométrie de masse MALDI-TOF pour différencier les anophèles infectés ou non par des plasmodiesVector-borne diseases are responsible for hundreds of thousands of cases of human infections and deaths each year worldwide. Generally, little is known about these diseases, caused by bacteria, viruses or parasites, sometimes emerging or re-emerging. Arthropods can be used as a tool for epidemiological monitoring of their associated microorganisms, some of which being able to be transmitted to vertebrate hosts. The identification of arthropods remains crucial in entomological investigations.We were able to detect potential new bacteria in ticks from Tahiti and triatomines in French Guiana.We explored the salivary microbiota of nearly a thousand mosquitoes from 3 different countries by 16S rRNA metagenomics. We have thus detected a large number of opportunistic pathogenic bacteria but also a very large number of genotypes probably corresponding to new bacterial species and genera. Finally, our major focus has been the development of the use of MALDI-TOF mass spectrometry in medical entomology. To overcome the limitations of existing arthropod identification reference methods, we validated the use of this tool for the identification of mosquitoes (collected in the field in Australia) and fleas (Spain, Corsica, Algeria). We have also developed its use for the identification of new families of arthropods, such as bed bugs (Cimicidae) and triatomines (Reduviidae). We were able to highlight the capacity of MALDI-TOF mass spectrometry to differentiate between anopheles infected or not by malaria parasites
34
Jones, Christina Michele. "Applications and challenges in mass spectrometry-based untargeted metabolomics." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54830.
Повний текст джерелаАнотація:
Metabolomics is the methodical scientific study of biochemical processes associated with the metabolome—which comprises the entire collection of metabolites in any biological entity. Metabolome changes occur as a result of modifications in the genome and proteome, and are, therefore, directly related to cellular phenotype. Thus, metabolomic analysis is capable of providing a snapshot of cellular physiology. Untargeted metabolomics is an impartial, all-inclusive approach for detecting as many metabolites as possible without a priori knowledge of their identity. Hence, it is a valuable exploratory tool capable of providing extensive chemical information for discovery and hypothesis-generation regarding biochemical processes. A history of metabolomics and advances in the field corresponding to improved analytical technologies are described in Chapter 1 of this dissertation. Additionally, Chapter 1 introduces the analytical workflows involved in untargeted metabolomics research to provide a foundation for Chapters 2 – 5.
Part I of this dissertation which encompasses Chapters 2 – 3 describes the utilization of mass spectrometry (MS)-based untargeted metabolomic analysis to acquire new insight into cancer detection. There is a knowledge deficit regarding the biochemical processes of the origin and proliferative molecular mechanisms of many types of cancer which has also led to a shortage of sensitive and specific biomarkers. Chapter 2 describes the development of an in vitro diagnostic multivariate index assay (IVDMIA) for prostate cancer (PCa) prediction based on ultra performance liquid chromatography-mass spectrometry (UPLC-MS) metabolic profiling of blood serum samples from 64 PCa patients and 50 healthy individuals. A panel of 40 metabolic spectral features was found to be differential with 92.1% sensitivity, 94.3% specificity, and 93.0% accuracy. The performance of the IVDMIA was higher than the prevalent prostate-specific antigen blood test, thus, highlighting that a combination of multiple discriminant features yields higher predictive power for PCa detection than the univariate analysis of a single marker. Chapter 3 describes two approaches that were taken to investigate metabolic patterns for early detection of ovarian cancer (OC). First, Dicer-Pten double knockout (DKO) mice that phenocopy many of the features of metastatic high-grade serous carcinoma (HGSC) observed in women were studied. Using UPLC-MS, serum samples from 14 early-stage tumor DKO mice and 11 controls were analyzed. Iterative multivariate classification selected 18 metabolites that, when considered as a panel, yielded 100% accuracy, sensitivity, and specificity for early-stage HGSC detection. In the second approach, serum metabolic phenotypes of an early-stage OC pilot patient cohort were characterized. Serum samples were collected from 24 early-stage OC patients and 40 healthy women, and subsequently analyzed using UPLC-MS. Multivariate statistical analysis employing support vector machine learning methods and recursive feature elimination selected a panel of metabolites that differentiated between age-matched samples with 100% cross-validated accuracy, sensitivity, and specificity. This small pilot study demonstrated that metabolic phenotypes may be useful for detecting early-stage OC and, thus, supports conducting larger, more comprehensive studies.
Many challenges exist in the field of untargeted metabolomics.
Part II of this dissertation which encompasses Chapters 4 – 5 focuses on two specific challenges. While metabolomic data may be used to generate hypothesis concerning biological processes, determining causal relationships within metabolic networks with only metabolomic data is impractical. Proteins play major roles in these networks; therefore, pairing metabolomic information with that acquired from proteomics gives a more comprehensive snapshot of perturbations to metabolic pathways. Chapter 4 describes the integration of MS- and NMR-based metabolomics with proteomics analyses to investigate the role of chemically mediated ecological interactions between Karenia brevis and two diatom competitors, Asterionellopsis glacialis and Thalassiosira pseudonana. This integrated systems biology approach showed that K. brevis allelopathy distinctively perturbed the metabolisms of these two competitors. A. glacialis had a more robust metabolic response to K. brevis allelopathy which may be a result of its repeated exposure to K. brevis blooms in the Gulf of Mexico. However, K. brevis allelopathy disrupted energy metabolism and obstructed cellular protection mechanisms including altering cell membrane components, inhibiting osmoregulation, and increasing oxidative stress in T. pseudonana. This work represents the first instance of metabolites and proteins measured simultaneously to understand the effects of allelopathy or in fact any form of competition.
Chromatography is traditionally coupled to MS for untargeted metabolomics studies. While coupling chromatography to MS greatly enhances metabolome analysis due to the orthogonality of the techniques, the lengthy analysis times pose challenges for large metabolomics studies. Consequently, there is still a need for developing higher throughput MS approaches. A rapid metabolic fingerprinting method that utilizes a new transmission mode direct analysis in real time (TM-DART) ambient sampling technique is presented in Chapter 5. The optimization of TM-DART parameters directly affecting metabolite desorption and ionization, such as sample position and ionizing gas desorption temperature, was critical in achieving high sensitivity and detecting a broad mass range of metabolites. In terms of reproducibility, TM-DART compared favorably with traditional probe mode DART analysis, with coefficients of variation as low as 16%. TM-DART MS proved to be a powerful analytical technique for rapid metabolome analysis of human blood sera and was adapted for exhaled breath condensate (EBC) analysis. To determine the feasibility of utilizing TM-DART for metabolomics investigations, TM-DART was interfaced with traveling wave ion mobility spectrometry (TWIMS) time-of-flight (TOF) MS for the analysis of EBC samples from cystic fibrosis patients and healthy controls. TM-DART-TWIMS-TOF MS was able to successfully detect cystic fibrosis in this small sample cohort, thereby, demonstrating it can be employed for probing metabolome changes.
Finally, in Chapter 6, a perspective on the presented work is provided along with goals on which future studies may focus.
35
Xu, Mingtian, and 許明田. "Multiscale transport of mass, momentum and energy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B3124497X.
Повний текст джерела
36
Kirkconnell, Carl Scott. "Numerical analysis of the mass flow and thermal behavior in high-frequency pulse tubes." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16434.
Повний текст джерела
37
Li, Qi. "Transmission loss of vehicle seals." Licentiate thesis, Stockholm : Farkost och flyg, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9792.
Повний текст джерела
38
Gans, Luiz Henrique Accorsi. "Modelo de predição para o crescimento de hidratos em paredes de tubulações." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/1884.
Повний текст джерелаАнотація:
CAPESNa indústria do petróleo existe um grande interesse no entendimento dos fenômenos de formação de hidratos já que eles podem danificar a tubulação, colocar vidas em risco e diminuir a produção de óleo e gás pelo bloqueio da linha. Ou seja, conhecer os fenômenos associados à formação de hidratos reflete diretamente no custo operacional da indústria petrolífera. Diversos grupos de pesquisa já propuseram diferentes modelos para predizer o crescimento de hidratos na interface líquido-gás e na parede das tubulações de produção de petróleo em águas profundas. Entretanto, os modelos baseados unicamente na transferência de calor não foram adequados para explicar os dados experimentais pois os consumos de água e gás não eram considerados. Assim, esta dissertação tem como objetivo desenvolver um modelo, matemático e numérico, que permita prever o crescimento dos hidratos de metano e de dióxido de carbono na parede da tubulação por meio das equações de conservação de massa e energia de forma acoplada. Como nenhuma solução analítica é possível, foi utilizado o método numérico dos volumes finitos com o esquema totalmente implícito. A verificação da implementação computacional foi realizada utilizando um modelo de dissociação de hidratos existente na literatura. A partir dos resultados numéricos, foi avaliado como as condições termodinâmicas, a porosidade e a condutividade térmica do hidrato, o diâmetro da tubulação e a disponibilidade de gás influenciam na taxa de crescimento de hidrato. Como principais resultados, verificou-se que a porosidade e a disponibilidade de gás representaram grande importância no cálculo da taxa de crescimento da camada de hidrato.
The study of the clathrate-hydrate formation processes in pipelines is very important to the oil and gas industry because these structures can stop production and it represents a safety risk due to the pressure build-up in the pipelines. Several research groups have proposed different models to predict how a hydrate film grows. However, the models based only on heat transfer could not explain satisfactorily the experimental data because the water and gas consumption were disregarded. So, in order to predict the hydrate growth phenomenon in tube wall, the current work presents a mathematical and numerical model for the coupled mass and energy balance problem for CO2 and CH4 hydrates. As a result of the coupling equations, no analytical solution is possible. So, a computational algorithm has been proposed based on the finite volume method and fully implicit scheme. The verification of the code was conducted through a dissociation model which has been presented by the literature. Although, its validation was not possible since no experimental data is currently available. The hydrate growth rate was evaluated by studying the influence of the thermodynamic conditions, the hydrate porosity and thermal conductivity, the pipe diameter and the gas availability. As a result, it has been noticed that the hydrate porosity and the gas availability had great influence in the hydrate growth rate.
39
Xiang, Maiqi. "Aerosol sampling and characterization technique using TEM porous grids." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2611.
Повний текст джерелаАнотація:
La caractérisation et l’analyse des particules nano/micromètriques solides en suspension dans l’air ont récemment reçu une attention considérable. Le prélèvement représentatif des particules à analyser est une exigence fondamentale. L’échantillonneur d’aérosols récemment développé appelé Mini Particle Sampler (MPS), qui est équipé d’une grille poreuse de Transmission Electron Microscopy (TEM), rend l’échantillonnage de particules possible. Cependant, l’exploitation des résultats de ce système d’échantillonnage est encore à l’étape précoce. Cette thèse améliore et quantifie le système d’échantillonnage MPS. En outre, une nouvelle méthode de caractérisation de la masse de polluants est développée sur la base du système d’échantillonnage optimisé. L’efficacité d’échantillonnage des particules dont le diamètre de mobilité varie de 5à 100 nm est principalement étudiée. Selon l’analyse de sensibilité des paramètres dans l’ensemble de la configuration effectuée par la méthode Taguchi, la concentration en sel de l’atomiseur, la polarité à haute tension dans Differential Mobility Analyzer (DMA), la méthode d’évaluation de l’efficacité d’échantillonnage, la température d’échantillonnage, et la porosité de la grille TEM affectent le moins possible l’efficacité de collection. L apetite taille des pores du filtre, le débit élevé et les particules plus denses augmentent l’efficacité de collection des particules, qui sont les principaux paramètres. Basé sur l’étude des mécanismes de filtration des grilles TEM et la comparaison des modèles théoriques disponibles, une méthode d’analyse expérimentale de l’efficacité de collection combinée à la modélisation théorique est développée en considérant l’applicabilité du modèle. En utilisant cette méthode, les effets des principaux paramètres mentionnés ci-dessus sont comparés entre les expériences et les théories. La technologie d’échantillonnage est optimisée et l’efficacité minimale de collecte peut atteindre 40% en ajustant les paramètres du système d’échantillonnage. De plus, selon les méthodes de Monte-Carlo, les incertitudes sur l’efficacité de collection à partir des données mesurées et des modèles sont généralement inférieures à 1% et à 9%, respectivement. La plupart des données d’efficacité de collection mesurées sont couvertes par la plage d’incertitude d’efficience simulée par les modèles. L’analyse de sensibilité basée sur la variance de Sobol montre que la taille des pores et le débit de prélèvement contribuent de manière significative aux incertitudes et nécessitent un contrôle pour améliorer la précision de l’efficacité. En outre, le facteur de correction de Cunningham est également un paramètre de sensibilité. Sur la base du développement ci-dessus du système d’échantillonnage MPS, une méthode quantitative est proposée pour caractériser la concentration de masse élémentaire des particules micrométriques en suspension dans l’air par échantillonnage de particules etTEM - Energy Dispersive X-ray Spectroscopy (EDS). Le principe est de collecter les particules en suspension dans l’air sur une grille TEM, puis d’y ajouter une certaine masse de particules de référence, et de déterminer les pourcentages relatifs de tous les éléments (particules de référence et particules inconnues) via EDS. Indépendamment de la condition d’échantillonnage, la collecte quantitative et homogène des particules monodispersées RbCl, CsCl et NaCl sur la grille TEM a pu être réalisée. Pour toutes les conditions testées, lors du dépôt de divers types de particules en suspension quantifiées sur une grille TEM, les écarts absolus entre les pourcentages de masse des éléments théoriques et les rapports expérimentaux mesurés par EDS restent inférieurs à 10%, qui confirme que la méthode proposée pourrait être utilisée pour la caractérisation massique d’éléments dans un aérosol inconnu. Le RbCl a été préféré comme référence depuis sa rareté dans les particules aéroportées habituelles et sa faible toxicitéCharacterization and analysis of airborne solid nano/micrometric particles have received considerable attention. The representative collection of particles to be analyzed is a fundamental requirement. The recently developed aerosol sampler called Mini Particle Sampler (MPS), which is equipped with a porous Transmission Electron Microscopy (TEM) grid, renders particle sampling convenient. However, the research for this useful sampling system is still in the initial stage. The thesis improves and quantifies the MPS sampling system. Besides, a new method of pollutant mass characterization is developed based on the optimizedsampling system. The sampling efficiency of the sampling system for particles with mobility diameters ranging from 5 to 100 nm is mainly investigated. According to the sensitivity analysis tof the parameters in the whole setup carried out by the Taguchi method, salt concentration of the atomizer, high-voltage polarity in the Differential Mobility Analyzer (DMA), sampling efficiency assessment method, sampling temperature, and porosity of the porous TEM gridminimally affect the collection efficiency. Small filter pore size, high flowrate, and denserparticles promote particle capturing, which are the main parameters. Based on the investigation of the filtration mechanisms of TEM grids and the comparison of available theoretical models, a method for experimental collection efficiency analysis combined with theoretical modeling is developed by considering the model’s applicability. Using this method, the effects of the main parameters mentioned above are compared between experiments andtheories. The sampling technology is optimized and the minimum collection efficiency isup to 40% by adjusting the parameter settings of the sampling system. In addition, accordingto the Monte-Carlo methods, sampling efficiency uncertainties from measured data andtheoretical models are generally less than 1% and 9%, respectively. Most sampling efficienciesmeasured data are covered by the efficiency uncertainty range simulated by models.Sobol variance-based sensitivity analysis shows that pore size and flowrate contribute significantly to the uncertainties, and require control to improve the efficiency precision. Besides, Cunningham correction factor is also a sensitivity parameter. Based on the above development of the MPS sampling system, a quantitative method is proposed to characterize the elemental mass concentration of airborne nano/micrometric particles via particle sampling and TEM - Energy Dispersive X-ray Spectroscopy (EDS). The principle is to collect airborne particles on a TEM grid, then add a certain mass of reference particles on it, and determine the relative percentages of all elements (reference and unknown particles) via EDS. Regardless of the sampling condition, the quantitative and homogeneously collection of monodisperse RbCl, CsCl, NaCl particles on the TEM grid could be achieved. For all the tested conditions, when depositing divers kinds of quantified airborne particles on one TEM grid, the absolute deviations between theoretical element mass percentages and experimental ratios measured by EDS remain lower than 10%, which confirms that the proposed method could be used for mass characterization of elements in an unknown aerosol. RbCl has been preferred as a reference since its rarity in usual airborne particles and having a low toxicity. The developed method has been used for characterizing aerosol released by the friction between serial pad and braking disc. The mass concentration of Fe in the braking aerosol is calculated as 0.105 μg/L using this method, which is consistent with the concentration range estimated from the data of Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS)
40
Alizadeh, Arash. "Étude de sorption, de transfert de matière et chaleur pendant la polymérisation de l'éthylène en phase gaz dans un procédé en mode condensée." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01066378.
Повний текст джерелаАнотація:
La polymérisation de l'éthylène en phase gaz en présence d'un système catalytique supporté en réacteurs à lit fluidisés reste le procédé le plus utilisé pour la production de polyéthylène à basse densité linéaire. De plus, dans le cas du polyéthylène à haute densité, celui-ci représente également une part non négligeable des plants de production à travers le monde. Le procédé en phase gaz offre de nombreux avantages dont un coût d'exploitations inférieures et une flexibilité supérieure en termes de production des différents types de polymères comparé aux autres procédés conventionnels. Cependant, au regard de la nature exothermique de la réaction de polymérisation, la vitesse de la production du polymère dans ces réacteurs est limitée par la vitesse à laquelle la chaleur produite par la réaction peut être évacuée. Si le réacteur ne permet pas l'évacuation de cette chaleur, l'augmentation de la vitesse de production résulterait en une croissance dramatique de la température au sein du réacteur et, par conséquent, à la fusion et l'agglomération du polymère, et finalement à l'arrêt du réacteur. Dans ce cas, dans le but d'avoir une vitesse de production plus importante, il est possible d'utiliser le réacteur susnommé en tant que mode d'opération condensé. Dans le cas de ce mode d'opération, le flux d'alimentation de la phase gaz du réacteur contient non seulement de l'éthylène, de l'azote, de l'hydrogène, et éventuellement un comonomère, mais également un agent condensant inerte (ACI) tels que le pentane ou l'hexane. Dans cette configuration, le flux d'alimentation est en partie liquéfié dans un échangeur de chaleur externe en le refroidissant sous le point de rosée du gaz. Par vaporisation de la phase liquide dans le réacteur, une quantité plus importante de chaleur peut être retirée de l'environnement du réacteur grâce à la chaleur latente associée à la vaporisation. Cela permet d'obtenir un rendement plus élevé de l'espace pour ce réacteur et par conséquent une vitesse de production supérieure
41
Narayanan, Shankar. "Gas assisted thin-film evaporation from confined spaces." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42780.
Повний текст джерелаАнотація:
A novel cooling mechanism based on evaporation of thin liquid films is presented for thermal management of confined heat sources, such as microprocessor hotspots. The underlying idea involves utilization of thin nanoporous membranes for maintaining microscopically thin liquid films by capillary action, while providing a pathway for the vapor generated due to evaporation at the liquid-vapor interface. The vapor generated by evaporation is continuously removed by using a dry sweeping gas keeping the membrane outlet dry. This thesis presents a detailed theoretical, computational and experimental investigation of the heat and mass transfer mechanisms that result in dissipating heat.
Performance analysis of this cooling mechanism demonstrates heat fluxes over 600W/cm2 for sufficiently thin membrane and film thicknesses (~1-5µm) and by using air jet impingement for advection of vapor from the membrane surface. Based on the results from this performance analysis, a monolithic micro-fluidic device is designed and fabricated incorporating micro and nanoscale features. This MEMS/NEMS device serves multiple functionalities of hotspot simulation, temperature sensing, and evaporative cooling. Subsequent experimental investigations using this microfluidic device demonstrate heat fluxes in excess of 600W/cm2 at 90 C using water as the evaporating coolant.
In order to further enhance the device performance, a comprehensive theoretical and computational analysis of heat and mass transfer at micro and nanoscales is carried out. Since the coolant is confined using a nanoporous membrane, a detailed study of evaporation inside a nanoscale cylindrical pore is performed. The continuum analysis of water confined within a cylindrical nanopore determines the effect of electrostatic interaction and Van der Waals forces in addition to capillarity on the interfacial transport characteristics during evaporation. The detailed analysis demonstrates that the effective thermal resistance offered by the interface is negligible in comparison to the thermal resistance due to the thin film and vapor advection. In order to determine the factors limiting the performance of the MEMS device on a micro-scale, a device-level detailed computational analysis of heat and mass transfer is carried out, which is supported by experimental investigation. Identifying the contribution of various simultaneously occurring cooling mechanisms at different operating conditions, this analysis proposes utilization of hydrophilic membranes for maintaining very thin liquid films and further enhancement in vapor advection at the membrane outlet to achieve higher heat fluxes.
42
Літвін, Роман Григорович. "Покращання експлуатаційних властивостей трансмісії автомобіля застосуванням двомасового маховика". Diss., Національний університет "Львівська політехніка", 2020. https://ena.lpnu.ua/handle/ntb/56117.
Повний текст джерела
43
Ross, Victor B. "Using rapid environmental assessment to improve the hazard prediction and assessment capability for weapons of mass destruction." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FRoss%5FMETOC.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, December 2003.Thesis advisor(s): Carlyle Wash, Neil Rowe. Includes bibliographical references (p. 47-48). Also available online.
44
Feraud, Géraldine. "Molécules et nanoparticules aromatiques du milieu interstellaire : production et caractérisation au laboratoire." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00889634.
Повний текст джерелаАнотація:
Ce travail de thèse traite d'expériences d'astrophysique de laboratoire sur des matériaux aromatiques, étudiés pour la plupart dans des conditions proches de celles rencontrées dans les milieux interstellaire et circumstellaire, comprenant rayons cosmiques et irradiations UV. Ces dernières sont à l'origine de bandes d'émission dans l'infrarouge moyen, dont les porteurs supposés sont principalement les Hydrocarbures Aromatiques Polycycliques (PAHs) et les nanoparticules aromatiques. Un nouveau spectromètre, FIREFLY (Fluorescence in the InfraRed from Excited FLYing molecules), contenant une réplique des filtres circulaires variables à bord de l'instrument ISOCAM du satellite ISO, a été mis au point et caractérisé au cours de cette thèse. Cet instrument a permis de mesurer la désexcitation infrarouge dans la région des modes d'élongations CH (3.3 µm, soit 3000 cm-1) des dérivés du benzène et du naphtalène à température ambiante, suite à l'absorption d'un photon UV. Ceci montre, avec l'appui de la modélisation, que la spectroscopie d'émission IR est un outil puissant permettant de comprendre les effets d'anharmonicité liés à l'énergie interne, l'isomérisation voire même la dynamique intramoléculaire non-adiabatique, au travers de la spectroscopie d'excitation de fluorescence infrarouge (une nouvelle technique). Ce travail est préliminaire à la future mesure de fluorescence infrarouge de nanoparticules aromatiques en phase gazeuse et à basse température produites par une flamme basse pression, dans le but de comparer les spectres de laboratoire avec les observations astrophysiques. Le dépôt d'énergie par les rayons cosmiques a été étudié grâce à une autre expérience, l'irradiation ionique d'analogues de poussières interstellaires et circumstellaires (suies produites par la flamme basse pression), mettant en évidence une réorganisation chimique. Les suies sont caractérisées par différents diagnostics complémentaires tels que la Microscopie Electronique en Transmission à Haute Résolution et les spectroscopies infrarouge à Transformée de Fourier et Raman. L'ensemble des informations tirées permet de mieux cerner la nanostructuration des analogues et ainsi mieux identifier les différentes signatures spectrales astrophysiques (interprétation de la bande à 7.7 µm comme une bande de défauts). Grâce à ces expériences, nous espérons améliorer notre compréhension de la structure, croissance et évolution de la poussière, d'un point de vue astrophysique.
45
Popoola, Oludélé Olusègun. "Amorphisation et précipitation superficielles induites par implantation ionique dans les alliages NiTi équiatomiques : application aux propriétés tribologiques." Poitiers, 1988. http://www.theses.fr/1988POIT2292.
Повний текст джерелаАнотація:
Mise en evidence par microscopie electronique en transmission, spectrometrie sims et photoelectron d'une amorphisation superficielle et de la formation de fins precipites cristallins tin::(x) dans le cas d'une implantation, d'azote. Influence de la temperature et de la dose d'ion sur l'epaisseur de la couche. Correlation entre la microstructure d'implantation et les proprietes tribologiques. Le coefficient de frottement se trouve reduit et la resistance a l'usure se trouve amelioree de facon durable. L'initiation et la propagation des processus de degradation sont ainsi ralenties
46
Löffler, Markus. "Nanomanipulation and In-situ Transport Measurements on Carbon Nanotubes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-33242.
Повний текст джерелаАнотація:
With the advent of microelectronics and micromechanical systems, the benefits of miniaturized technology became evident. With the discovery of carbon nanotubes by Iijima in 1991, a material has been found that offers superior porperties such as high tensile strength, excellent electrical and heat conductivity while being lightweight, flexible and tunable by the specific atomic arrangement in its structure. The first part of this thesis deals with a new synthesis approach, which combines the known routes of chemical vapour deposition and laser ablation. The results concerning diameter and yield fit well within an established model for the nucleation and growth of carbon nanotubes and extend it by considering a larger parameter space. Furthermore, conventional laser ablation has been used to synthesize C-13 augmented carbon nanotubes, whose diameters depend among the usual synthesis parameters also on the C-13 content, an influence which is in line with the changed thermal conductivities of isotope mixtures. Manipulation of carbon nanotubes inside a transmission electron microscope forms the second part of this thesis. With the help of an in-situ nanomanipulator, several experiments involving the mechanical and electrical properties of carbon nanotubes have been performed. Two-probe resistances of individual nanotubes have been measured and the observation of individual shell failures allowed for the determination of current limits per carbon shell. With the help of electrical current, a nanotube was modified in its electrical characteristics by reshaping its structure. By application of DC-currents or square current pulses, the filling of iron- or cementite-filled multi-wall carbon nanotubes has been found to move in a polarity-defined direction guided by the nanotube walls. Depending on the current, nanotube shape, and composition of the filling different regimes of material transport have been identified, including the reworking of the inner nanotube shells. The application of a high driving current leads to a complete reworking of the host nanotube and the current-induced growth of carbonaceous nanostructures of changed morphology. Utilizing the obtained results, a transport mechanism involving momentum transfer from the electron wind to the filling atoms and a solid filling core during transport is developed and discussed. Finally, measurements of mechanical properties using electrically induced resonant or non-resonant vibrations inside the transmission electron microscope have been observed and important mechanical parameters have been determined with the help of a modified Euler-Bernoulli-beam approachMit dem Aufkommen von Mikroelektronik und mikromechanischen Systemen wurden die Vorteile miniaturisierter Geräte augenscheinlich. Mit der Entdeckung von Kohlenstoff-Nanoröhren durch Iijima 1991 wurde ein Material gefunden, welches überlegene Eigenschaften wie hohe Festigkeit, exzellente elektrische und Wärmeleitfähigkeit zeigt, während es zeitgleich leicht und flexibel ist. Diese Eigentschaften können durch eine Änderung der spezifischen atomaren Anordnung in der Nanoröhrenhülle beeinflusst werden. Der erste Teil dieser Dissertationsschrift behandelt einen neuartigen Syntheseansatz, welche die bekannten Syntheserouten der chemischen Gasphasenabscheidung und Laserablation kombiniert. Die Ergebnisse bezüglich des Durchmessers und der Ausbeute lassen sich gut mit einem etablierten Modell der Nukleation und des Wachstums von Kohlenstoff-Nanoröhren beschreiben - sie erweitern es, indem sie einen größeren Parameterraum berücksichtigen. Des Weiteren wurde konventionelle Laserablation benutzt, um C-13 angereicherte Kohlenstoff-Nanoröhren herzustellen, deren Durchmesser nicht nur von den üblichen Parametern, sondern auch vom C-13 Anteil abhängt. Diese Abhängigkeit geht mit der veränderten thermischen Leitfähigkeit von Isotopenmischungen einher. Die Manipulation von Kohlenstoff-Nanoröhren in einem Transmission-Elektronenmikroskop formt den zweiten Teil der Dissertationschrift. Mit Hilfe eines in-situ Manipulators wurden vielfältige Experimente durchgeführt, um die mechanischen und elektrischen Eigenschaften der Kohlenstoff-Nanoröhren zu bestimmen. Zweipunktmessungen des Widerstands einzelner Nanoröhren und die Beobachtung des Versagens einzelner Kohlenstoffschichten erlaubte die Bestimmung der Stromtragfähigkeit einzelner Hüllen. Mit Hilfe eines elektrischen Stromes konnte eine Nanoröhre durch die veränderung der Struktur in ihren elektrischen Eigenschaften verändert werden. Unter Verwendung dauerhaften oder gepulsten Gleichstroms konnte die Eisen- oder Zementit-Füllung der Kohlenstoff-Nanoröhren in eine polaritätsabhängige Richtung bewegt werden. Die Füllung wurde dabei durch die Wände der Nanoröhre geführt. Abhängig von Strom, Form der Nanoröhre und Zusammensetzung der Füllung ließen sich verschiedene Bereiche des Materialtransports identifizieren, u.a. das Umarbeiten einiger innerer Kohlenstoffschichten. Ein hoher Strom hingegen bewirkt eine Umarbeitung der kompletten Nanoröhre und strominduziertes Wachstum von Kohlenstoff-Nanostrukturen mit veränderter Morphologie. Mit Hilfe der gewonnenen Resultate wurde ein Transportmodell entwickelt, welches den Impulstransfer von Elektronen an Füllungsatome sowie einen festen Füllungskern während des Transports diskutiert. Messungen der mechanischen Eigenschaften, welche mit Hilfe von resonanter oder nicht-resonanter elektrischer Anregung von Schwingungen im Transmissions-Elektronenmikroskop durchgeführt wurden bilden den Abschluss der Arbeit. Durch die Beobachtungen konnten mit einem modifizierten Euler-Bernoulli-Balkenmodell wichtige mechanische Eigenschaften bestimmt werden
47
Anxionnaz, Françoise. "Microstructure et composition chimique de composites sic/si : :(3)n::(4)." Paris 6, 1987. http://www.theses.fr/1987PA066141.
Повний текст джерелаАнотація:
On etudie par microscopie (meb, met, eels, edx) et par analyse par sonde ionique (sims) les composites prepares par impregnation de fibres de sic par depot chimique en phase vapeur de si::(3)n::(4) ou sic. On etudie l'influence du substrat sur la microstructure des depots, puis on caracterise la microstructure et la composition chimique de fibres elementaires de sic revetues par cvd de c et de sic. L'analyse des fibres revetues et tout particulierement de l'interface fibre/matrice montre la complementarite des methodes eels et sims pour caracteriser les composites a fibres longues
48
Blais, Catherine. "Rôle et métabolisme des ecdystéroïdes au niveau des disques imaginaux alaires de Pieris brassicae L. (Lepidoptère)." Paris 6, 1986. http://www.theses.fr/1986PA066217.
Повний текст джерелаАнотація:
Les disques imaginaux alaires de larves âgées et de prénymphes de Pieris brassicae (Lépidoptère) se différencient in vitro en présence d'ecdysone (0,2-4 mu m) ou de 20-hydroxyecdysone (0,2 mu m). Ces hormones sont métabolisées par les tissus imaginaux (organes entiers, homogénats ou fractions subcellulaires); les réactions intéressent trois positions de la molécule d'ecdysone: les carbones c-26 (26-hydroxylation et formation d'acides ecdysonoïques), c-20 (20-hydroxylation) et c-3 (formation réversible de dérivés 3-déhydro). Les systèmes enzymatiques responsables des réactions d'oxydation en c-20 (microsomal) et d'oxydo-réduction en c-3 (cytosolique) ont été caractérisés chez les chrysalides. Cette étude soulève le problème de la signification physiologique de ce métabolisme des ecdystéroïdes (inactivation et/ou transformation en métabolites actifs biologiquement) dans les disques imaginaux, organes-cibles des hormones
49
Flyktman, Stefan, and Jan Johansson. "Tillverkningsmetoders påverkan på en transmissions vikt och tillverkningskostnad." Thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-15540.
Повний текст джерелаАнотація:
Volvo Powertrain, VPT, i Köping tillverkar idag växellådor för tunga fordon. Till medeltunga fordon köper Volvo växellådor från bland annat underleverantören ZF. Volvo vill undersöka scenariot att ta fram AMT - växellådor för medeltunga fordon. I-shift modellen AT2412, som är dimensionerad för en max belastning på 2400 Nm och anpassad för tunga lastbilar, skulle kunna fungera även i medeltunga fordon men är då överdimensionerad och onödigt tung. Med tanke på kommande utvecklingsprojekt behöver Volvo öka sin kunskap hur val av tillverkningsmetoder påverkar vikt och tillverkningskostnader. Det behövs för att öka förståelsen för hur olika prioriteringar ska göras med avseende på vikt och tillverkningskostnader. Examensarbetets syfte var att ge denna förståelse för hur olika tillverkningsprocesser påverkar en transmissions utformning med avseende på mått och vikt utifrån ett givet momentområde. Målet med examensarbetet var att påvisa samband mellan valet av tillverkningsmetoder för enskilda artiklar och hur mycket det kan påverka den kompletta transmissionens vikt samt tillverkningskostnad. Arbetet var avgränsat till att analysera modifierade kugghjul i baslådan. Första delen av arbetet bestod av att dimensionera nya kugghjul anpassade för max belastning på 1600 Nm, detta utifrån samma produktionsupplägg som för befintliga kugghjul som återfinns i bland annat AT2412. Den andra delen bestod av att ta fram faktorer för hur olika tillverkningsmetoder påverkar dimensioneringen och för varje enskilt kugghjul beräkna vikt och tillverkningskostnad då åtta kombinationer av tillverkningsmetoder används. Avslutningsvis gjordes en summering för att visa vilka varianter som ger en optimal växellåda utifrån minimal vikt respektive minimal tillverkningskostnad. Resultatet visar att valet av tillverkningsmetoder leder till att vikten på kugghjulen kan reduceras mer eller mindre. Generellt visar beräkningarna att kugghjul som slipas, kulpenas och manganfosfateras får lägst vikt och blir dyrast att producera. Lägsta tillverkningskostnad uppnås genom att vissa tillverkningsprocesser som kulpening och manganfosfatering utesluts men detta måste då kompenseras med ökad kuggbredd vilket leder till högre vikt. Om VPT väljer att ta fram en ny variant av I-shift där kugghjulen är dimensionerade för 1600Nm så kan växellådan göras 6-11 kg lättare och tillverkningskostnaderna för kugghjulen kan minska med ca 10 procent.Volvo Powertrain, VPT, in Köping currently manufactures transmissions for heavy-duty vehicles. For medium-duty vehicles Volvo purchase transmissions from their parts supplier ZF. Volvo wants to investigate the scenario to develop AMT - gearboxes for medium-duty vehicles. The I-shift model AT2412, which is designed for a maximum load of 2400 Nm and adapted for heavy-duty vehicles, would be able to function even in the medium-duty vehicles, but would be oversized and excessively heavy. In view of future development Volvo need to increase their knowledge in how the choices of manufacturing methods affect the mass and the manufacturing costs. They need to increase the understanding to make the optimal priorities with respect to mass and manufacturing costs. This study aimed to provide this understanding of how different processes affect a transmission design with respect to mass and measures from a given torque range. The aim of the study was to demonstrate the influence of the choice of production methods for individual items and how much it can affect the complete transmission's mass and manufacturing cost. The work was limited to analyzing the modified gears in the base unit. The first part of the work consisted of designing new gears designed for a maximum load of 1600 Nm, based on the same list of operations as the existing gears, which are found in AT2412. The second part consisted of revealing the factors for the different processes affecting the design regarding to fatigue and structural strength. For eight combinations of manufacturing processes the mass and manufacturing cost was calculated for each gear. Finally, a summary was made to show which combination of manufacturing methods that would give the optimum transmission based on minimum mass and minimum manufacturing cost. The results show that the choice of production methods leads to more or less reduction of mass of the gears. Generally, the calculations show that the gear that is ground, shootpeened and manganese phosphated get the lowest mass and become the most expensive to produce. On the other hand, lower manufacturing cost can be achieved by excluding certain manufacturing operations as shootpeening and manganese phosphate, but this must be compensated by increased facewidth of the gear, leading to increased mass. If VPT decide to develop a new variant of the I-shift in which the gears are designed for 1600Nm then the gearbox can be 6-11 kg lighter and the manufacturing costs of the gears can be reduced by about 10 percent.
50
Ruau, Olivier. "Applications de la microspectroscopie IRTF en modes transmission et réflexion spéculaire à la caractérisation chimique des matières organiques." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL146N.
Повний текст джерелаАнотація:
Le couplage d'un spectromètre infrarouge et d'un microscope permet d'utiliser les potentialités de la spectroscopie IR à l'échelle microscopique. La microspectroscopie IR a été testée en géochimie organique afin de résoudre les problèmes liés à l'étude de la matière organique. En transmission, l'utilisation d'une enclume à fenêtres de diamant a permis de simplifier le protocole de préparation des échantillons et a conduit à des spectres de qualité très supérieure à ceux issus de l'analyse sur pastilles de KBr. Parallèlement un protocole de préparation des composés solubles (résines et asphaltènes) a été mis au point. Ainsi, la microspectroscopie IRTF en mode transmission a pu être utilisée pour la mise en évidence des mécanismes de transformation de la matière organique au cours de la maturation. En exploration pétrolière, la microspectroscopie IRTF en mode réflexion spéculaire se révèle particulièrement adaptée pour le contrôle chimique in situ des vitrinites. Les résultats montrent que le pouvoir réflecteur de la vitrinite utilisé dans les modèles mathématiques pour reconstruire l'histoire des bassins, peut être influencé par d'autres phénomènes que la maturation. Il a été mis en évidence que l'oxydation du matériel organique ou l'origine botanique des vitrinites sont des facteurs qui perturbent l'interprétation du pouvoir réflecteur en tant que paramètre de maturité. La versatilité de la microspectroscopie IRTF ainsi que la qualité des renseignements qu'elle fournit ont permis de démontrer ses potentialités dans le domaine de la géochimie organique