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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The effects of evaporation rate, solvent, and substrate on the surface segregation of block copolymers

Lawson, Glenn E. 04 March 2009 (has links)
The surface chemistry of two systems of block copolymers was studied using angular dependent X-ray Photoelectron Spectroscopy poly(dimethyl (XPS). Surface concentration siloxane-b-sulfone)/polysulfone profiles of [PDMS/PSF] blends cast at several rates of solvent evaporation, and cast on several substrates were measured. Surface concentration profiles of poly(styrene-butadiene-styrene) poly(styrene-isoprene-styrene) [SIS] triblock [SBS] and copolymers cast at several rates of solvent evaporation, and cast from two different solvents were also measured. The concentration profile analyses were made using three different XPS quantification techniques. The PDMS/PSF systems were analyzed using the peak area ratio, and the SBS and SIS copolymers were analyzed using both the Cls shakeup to main ratio, and spectral measurements of the valence band. The results of this study indicate a variation in surface concentration as well as concentration gradient for different sample preparation routes. The variations can be explained by considering the rate of film formation (kinetics), polymer - solvent interactions, and polymer - substrate interactions. However, in both systems the lower surface energy copolymer block (siloxane block, or diene block) preferentially segregated to the surface for all of the sample preparation routes stUdied. / Master of Science
22

Effect of source water blending on iron and lead release : thermodynamic and statistical modeling

Tang, Zhijian 01 October 2003 (has links)
No description available.
23

On Visualizing Branched Surface: an Angle/Area Preserving Approach

Zhu, Lei 12 September 2004 (has links)
The techniques of surface deformation and mapping are useful tools for the visualization of medical surfaces, especially for highly undulated or branched surfaces. In this thesis, two algorithms are presented for flattened visualizations of multi-branched medical surfaces, such as vessels. The first algorithm is an angle preserving approach, which is based on conformal analysis. The mapping function is obtained by minimizing two Dirichlet functionals. On a triangulated representation of vessel surfaces, this algorithm can be implemented efficiently using a finite element method. The second algorithm adjusts the result from conformal mapping to produce a flattened representation of the original surface while preserving areas. It employs the theory of optimal mass transport via a gradient descent approach. A new class of image morphing algorithms is also considered based on the theory of optimal mass transport. The mass moving energy functional is revised by adding an intensity penalizing term, in order to reduce the undesired "fading" effects. It is a parameter free approach. This technique has been applied on several natural and medical images to generate in-between image sequences.
24

以技術分析市場時機的效果驗證

葉日武, YE, RI-WU Unknown Date (has links)
共一冊,約四萬字,分五章。第一章係概論,簡述研究動機、目的、方法、及各項基 本假設。第二章為技術分析簡介,說明技術分析的一般理念,以及各種技術分析的方 法。第三章是文獻探討,就國內外過去對技術分析所作的實證研究加以敘述。第四章 為本研究中各項技術分析方法的實證應用結果,包括單一方法研判及綜合研判的效果 。最後,在第五章彙總本研究的結論,並提出進一步研究的建議。
25

Interfacial Electrochemistry and Surface Characterization: Hydrogen Terminated Silicon, Electrolessly Deposited Palladium & Platinum on Pyrolyzed Photoresist Films and Electrodeposited Copper on Iridium

Chan, Raymond 12 1900 (has links)
Hydrogen terminated silicon surfaces play an important role in the integrated circuit (IC) industry. Ultra-pure water is extensively used for the cleaning and surface preparation of silicon surfaces. This work studies the effects of ultra-pure water on hydrogen passivated silicon surfaces in a short time frame of 120 minutes using fourier transform infrared spectroscopy – attenuated total reflection techniques. Varying conditions of ultra-pure water are used. This includes dissolved oxygen poor media after nitrogen bubbling and equilibration under nitrogen atmosphere, as well as metal contaminated solutions. Both microscopically rough and ideal monohydride terminated surfaces are examined. Hydrogen terminated silicon is also used as the sensing electrode for a potentiometric sensor for ultra-trace amounts of metal contaminants. Previous studies show the use of this potentiometric electrode sensor in hydrofluoric acid solution. This work is able to shows sensor function in ultra-pure water media without the need for further addition of hydrofluoric acid. This is considered a boon for the sensor due to the hazardous nature of hydrofluoric acid. Thin carbon films can be formed by spin coating photoresist onto silicon substrates and pyrolyzing at 1000 degrees C under reducing conditions. This work also shows that the electroless deposition of palladium and platinum may be accomplished in hydrofluoric acid solutions to attain palladium and platinum nanoparticles on a this film carbon surface for use as an electrode. Catalysis of these substrates is studied using hydrogen evolution in acidic media, cyclic voltammetry, and catalysis of formaldehyde. X-ray diffractometry (XRD) is used to ensure that there is little strain on palladium and platinum particles. Iridium is thought to be a prime candidate for investigation as a new generation copper diffusion barrier for the IC industry. Copper electrodeposition on iridium is studied to address the potential of iridium as a copper diffusion barrier. Copper electrodeposition is studied using a current-transient technique to obtain insight into the nucleation and growth mechanism. Copper on iridum was annealed up to 600 degrees C. X-ray photoelectron spectroscopy and XRD confirm that electrodeposited copper exists in a metallic state. XRD shows that copper exists in the characteristic face-centered cubic (111) form. XRD also confirms the stability of the copper-iridium interface with no new peaks after annealing, which is indicative that no interaction occurs. Scanning electron microscopy, and Scotch ® Tape peel tests confirm the uniformity and strength of copper on iridium even after annealing to 600 degrees C.
26

The effects of material treatments on the surface properties of polymeric biomaterials

Vase, Ajoy January 2007 (has links)
This work examines the chemical and physical effects of a material treatment process on the biopolymers PEEK, POM-h, POM-c, PTFE and UHMWPE. The polymers are analyzed physically and chemically using atomic force microscopy, profilometry, scanning electron microscopy, optical microscopy, contact angle measurement, FT infra-red spectroscopy and energy dispersive X-ray spectrometry. PEEK is found to be the most suitable polymer and FT Infra-red spectroscopy an informative analytic tool.
27

The Effects of Material Treatments on the Surface Properties of Polymeric Biomaterials

Vase, Ajoy 01 May 2007 (has links)
This work examines the chemical and physical effects of a material treatment process on the biopolymers PEEK, POM-h, POM-c, PTFE and UHMWPE. The polymers are analyzed physically and chemically using atomic force microscopy, profilometry, scanning electron microscopy, optical microscopy, contact angle measurement, FT infra-red spectroscopy and energy dispersive X-ray spectrometry. PEEK is found to be the most suitable polymer and FT Infra-red spectroscopy an informative analytic tool.
28

Analýza interní komunikace a využití nástrojů ICT pro komunikaci v konkrétní organizaci / Analysis of internal communication and utilization of ICT for communication in a specific organization

Jeništová, Tereza January 2017 (has links)
The purpose of this thesis is to analyze internal communication in a specific company and propose possible improvements. Such proposal is based on surveys and interviews with company owner. Theoretical part includes definition of internal communication, its effect on company´s functioning process and factors that influence it. Mentioned are also different communication instruments, mainly ICT instruments that can be effectively used for company´s internal communication. Practical part applies acquired findings on a specific situation in a specific company. Aim of this research is to analyze current situation of internal communication, determine its weaknesses and propose possible solutions of their removal.
29

29. Sächsische Fachtagung Umformtechnik

28 November 2023 (has links)
Unter dem Titel „Neue Wege in der Umformtechnik“ werden am 27. und 28.11.2023 anlässlich der 29. Sächsischen Fachtagen für Umformtechnik Vertreter aus Industrie und Forschung Ihre Entwicklungen und Forschungsarbeiten im Bereich der Umformtechnik in Dresden vorstellen. Die Professur Formgebende Fertigungsverfahren der Technischen Universität Dresden lädt dazu alle interessierten Fachbesucher in das Maritim Hotel & Internationales Congress Center Dresden nahe der Altstadt ein.
30

Probing the influence of bimetallic composition on the Pd/Au catalysed synthesis of vinyl acetate monomer

Haire, Andrew Richard January 2010 (has links)
Scanning Tunnelling Microscopy (STM) was utilised together with the high resolution depth-profiling capabilities of Medium Energy Ion Scattering (MEIS), a technique traditionally associated with single crystal substrates, to probe the mean size and depth dependent composition profile of bimetallic PdAu nanoparticles on planar oxide surfaces as functions of the starting composition and annealing temperature. In order to fit composition profiles to experimental MEIS data, a new analysis tool has been designed that models the particles as flat-topped structures with a hexagonal base which can be divided into a number of shells, each shell corresponding to a particular ion pathlength inside the material. The reliability of this method will be discussed in detail. Fitting results show that the surface layers are always significantly enriched in Au compared to the bulk alloy composition. By comparing MEIS data for clean surfaces data for modified surfaces it was found that Pd generally segregates towards the particle surface on adsorption of acetic acid. The interaction of potassium acetate with Au/Pd{111} alloy surfaces of varying composition has been investigated using Temperature Programmed Desorption (TPD) and Reflection Absorption Infra Red Spectroscopy (RAIRS). At lower coverage, potassium acetate reacts reversibly with the surface to form CO and carbonate. Formation of surface acetate is observed on Pd-rich surfaces only. At higher coverage, acetate is the major surface species formed on all samples examined.

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