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Applications of chiral selectors and replaceable supports for capillary electrophoretic separationsWickramanayake, Priyanga, s3028858@student.rmit.edu.au January 2007 (has links)
The popularity of capillary electrophoresis (CE) as a separation technique has been established over the years. CE offers the advantages of high resolution, high separation efficiency, fast approaches of method development, a range of operational modes and low consumption of reagents. The strategy employed here for the development of chromatographic separations involved the utilization of experimental designs, multi-linear regression and response surface methodology to build empirical models that related the chromatographic quality to the factors influencing the separation. Separation of Nitrofuran antibiotics (NFAs) and their metabolites (NFMs) by using micellar electrokinetic capillary chromatography was successfully completed. The best conditions found to give optimum resolution from the optimization study was pH 9.0, 80 mM SDC concentration, 16 kV with running buffer consisting of 20 mM borate and 20 mM phosphate concentration using a 73 cm x 75 Ým column, resulting in completely resolved NFAs and NFMs within 16 min. It is interesting that all the compounds can be reliably separated with the one mixture, and single CE condition. Whilst all antibiotics have shorter migration time than their respective derivatised metabolites, as a group apart from nitrofurantoin the antibiotics elute before the metabolites. The analytical figures of merit for CE analysis exhibited excellent reproducibility of absolute and relative migration times, and acceptable reproducibility of relative response areas. Successful separation of metabolite derivatives was achieved when the developed method was applied to a spiked prawn sample. The chiral separation of Triadimenol was successfully completed using micellar electrokinetic capillary chromatography. The best conditions found to give optimum resolution from the optimisation study were pH 6.0, 20% methanol, 50 mM SDS concentration, 18 kV with running buffer consisting of 20 mM borate and 20 mM phosphate concentration using a 64.5 cm x 50 Ým column, resulted in baseline resolution of all Triadimenol isomers within 18 min. The optimised separation conditions were applied to a blank grape sample and to a spiked grape sample. No peaks were observed in the blank grape sample whereas the spiked grape sample had two diastereoismer peaks with poor detection sensitivity. Increase in detection sensitivity is necessary to determine the possibility of resolution of all the isomers of Triadimenol, in the spiked grape sample and the blank. Online preconcentration techniques were attempted to for Triadimenol isomer separation. When using online preconcentration technique of sweeping, a 30-fold increase in detection sensitivity of Triadimenol was observed compared to MEKC mode. However enantiomer separation was not possible with sulfated-£]-CD chiral selector. The best conditions were found to be pH 2.5, 50 mM SDS concentration, -20 kV with running buffer consisting of 20 mM phosphate concentration, using a 64.5 cm x 50 Ým column, resulting in diastereoisomer separation within 8 min. Final stage of the project was to create stationary phase beds in capillaries and micro-channels that could be removed and re-created, thus providing a fresh stationary phase. The replaceable stationary phase (RSP) can be used as an operating mode of CE/CEC. Preparation of reversible stationary phase (RSP) inside the capillary column was successfully performed using low methoxy pectin (LMP). LMP renders a capability of reversible thermogelation. Electroosmotic flow (EOF) and sufficient hydrophobicity of LMP gel allow separation of analyates. The porosity of LMP RSP was adequate to support EOF. Successful separation with good reproducibility of areas and migration times was obtained for Caffeine, Aspartame, Benzoic acid, Saccharine (CABS) mixture and NFAs. After performing continuous analyses, the aging of RSP was observed. Temperature was the ¡¥switch¡¦, which applied to remove aged RSP. RSP was recreated for further analysis of analytes. RSP was UV transparent, capable of handling various analytes and diff erent buffer electrolytes including aqueous-organic solvents.
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Seismic Performance of Steel Moment-resisting Frames with Nonlinear Replaceable LinksShen, Yunlu 14 July 2009 (has links)
This thesis presents the development and the seismic performance evaluation of steel MRFs with nonlinear replaceable links. Although existing MRFs can provide life safety during a design level earthquake, they are expected to sustain significant damage at the locations of flexural yielding fuses in the beams. The design of the fuse is also interlinked with the design of the beam, often resulting in over-design. These drawbacks can be mitigated by introducing replaceable links at the locations of expected inelastic action.
Four full-scale beam-to-column subassemblages with two link types were tested under cyclic loading: i) double channels with bolted web connections, ii) W-sections with bolted end plate connections. The experiments demonstrated that MRFs with replaceable links can provide strength and ductility equivalent to existing MRFs. Finite element models were then developed to capture the observed experimental responses, including local buckling, bolt slipping, and bolt bearing. Finally, preliminary design guidelines were proposed.
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Seismic Performance of Steel Moment-resisting Frames with Nonlinear Replaceable LinksShen, Yunlu 14 July 2009 (has links)
This thesis presents the development and the seismic performance evaluation of steel MRFs with nonlinear replaceable links. Although existing MRFs can provide life safety during a design level earthquake, they are expected to sustain significant damage at the locations of flexural yielding fuses in the beams. The design of the fuse is also interlinked with the design of the beam, often resulting in over-design. These drawbacks can be mitigated by introducing replaceable links at the locations of expected inelastic action.
Four full-scale beam-to-column subassemblages with two link types were tested under cyclic loading: i) double channels with bolted web connections, ii) W-sections with bolted end plate connections. The experiments demonstrated that MRFs with replaceable links can provide strength and ductility equivalent to existing MRFs. Finite element models were then developed to capture the observed experimental responses, including local buckling, bolt slipping, and bolt bearing. Finally, preliminary design guidelines were proposed.
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Vanová korba pro dvounápravový traktorový návěs / Dump body for twoaxles tractor semitrailerPrášek, Ondřej January 2009 (has links)
Graduation work discusses a design of the tube body of the tractor semi-trailer enabling double-sided tilting. The aim was a conceptual proposal of the semi-trailer body and a strength calculation with Finite Element Method on my own. A part of the work is also design documentation. The work puts major requirement on the simplest mechanical design. The body is a part of the replaceable system of the trailer body by ZDT Company and it is designed for a universal carriage unit MEGA 20.
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Design and Testing of a Replaceable Connection for Steel Concentrically Braced FramesStevens, Daniel January 2017 (has links)
There is increasing demand, from both engineers and their clients, for structures that can be rapidly returned to occupancy following an earthquake, while also maintaining or reducing initial costs. One possible way towards this goal is to ensure that seismic damage occurs only within elements that can be removed and replaced following a damaging earthquake. For concentrically braced frames that use hollow structural sections, the current design practice requires field welding of the brace to the gusset in a way that causes the brace to buckle out-of-plane. In the event of a damaging earthquake, the out-of-plane brace buckling may damage both the gusset plate and also any adjacent exterior cladding. The plate cannot be easily replaced, resulting in expensive and time-consuming repairs, and the damaged cladding could endanger the lives of people evacuating the building and of other pedestrians.
Through multiple design iterations, a new steel concentrically braced frame connection type was developed that can be bolted into place and that confines damage to replaceable components. The proposed connection is expected to result in reduced erection costs and be easier to repair following a major earthquake. Moreover, the new connection causes buckling to occur in-plane, preventing dangerous damage to the cladding.
Large scale experimental testing on two variations of the new connection was performed. The cyclic, uniaxial testing of a brace with the new connection demonstrated the connection’s ability to behave in a desirable manner, with tensile yielding, brace buckling and connection rotation occurring during the expected drift levels associated with earthquake loading. A nonlinear finite element model of a brace with the new connection was developed and discussed. The finite element model was able to replicate the results of the experiment and will allow for further research and development of the new connection. The new connection shows promise as a replaceable connection for the seismic design of concentrically braced frames. / Thesis / Master of Applied Science (MASc) / Earthquakes can cause major, devastating damage to city structures. The cost of repairs and the time needed to make those repairs can be crippling, to the point where it is easier to tear down the structures than properly repair them. Designers and engineers need improved ways to design these structures to be more easily repaired, without driving up the initial cost of the structure.
This research developed, tested and modelled a new, replaceable connection for earthquake resistant braces. The new connection is easier to install, easier to replace and provides added safety when compared to traditional designs.
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A Probing System with Replaceable Tips for Three Dimensional Nano-MetrologyMrinalini, R Sri Muthu January 2017 (has links) (PDF)
With increase in the number of three dimensional (3-D) nanometer-scale objects that are being either fabricated or studied, there is a need to accurately characterize their geometry. While the Atomic force microscope (AFM) is a versatile tool for performing nano-metrology, it suffers from issues of poor accessibility of 3-D features and inability to measure 3-D forces that limit its applicability in 3-D nano-metrology. This thesis investigates the design and development of a novel probing system based on AFM that improves accessibility and enables direct measurement of 3-D forces acting on the AFM tip.
Two approaches are investigated to address the issue of poor accessibility. The first is to develop a novel system that enables in-situ replacement and reuse of specialized AFM tips that improve accessibility, and the second is to design a special AFM tip that can actively re-orient about two independent axes.
In order to perform in-situ tip replacement, a liquid meniscus based micro-gripper is developed and integrated on to a conventional AFM probe. The stiffness of the gripper is analyzed and shown to be adequately high along all three axes for AFM imaging to be performed. Tip replacement and re-use are both experimentally demonstrated by employing a novel tip-exchange station. The replaced tips are employed to show artifact-free AFM imaging of a standard calibration grating in both tapping-mode and contact-mode.
To actively re-orient a conventional tip, a novel magnetically-actuated micro-scale ball-and-socket joint is integrated onto an AFM probe. The quasi-static behavior of the joint is experimentally characterized, and the ability of the tip to independently re-orient about two axes is demonstrated. The achieved range is about +/- 90 degrees about both X- and Y-axes.
In order to realize the potential of the proposed probes for 3-D nano-metrology, an AFM is developed in-house that possesses the capability to make direct measurement of 3-D forces. Optimization of the measurement system to achieve identical sensitivities and resolution along all three axes is studied. Subsequently, the necessary electronics for measurement, actuation and control are developed. All the subsystems are experimentally calibrated and integrated. The overall AFM is shown to have a resolution of about 0.2 nm when operated in tapping-mode. The developed AFM is employed to showcase the following applications: characterization of the coefficient of kinetic friction of Muscovite mica, force controlled nano-scribing on polymethyl methacrylate (PMMA) and tapping-mode imaging of a calibration grating with the developed re-orientable AFM probe. Finally, the unique ability of the re-orientable AFM probe to control its tip-orientation is employed to develop a nanometer-scale coordinate measurement machine (CMM). The developed nano-CMM is shown to access the vertical wall of a sample and obtain its topography.
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Velkoobjemová nástavba pro nosič výměnných nástaveb pro agrotahač 6 x 6 / Large volume carrier body for swap bodies for agri truck 6 x 6Tůma, Martin January 2015 (has links)
This diploma thesis deals with proposal large volume carrier body for swap bodies with volume 60 m3. In beginning the thesis includes background research part. In the middle part describes the design of conception body. Work in the last part contains the strength calculations using the finite element method. Strength checks consider especially deformation and strain analysis in different load angle states. Part of the thesis is also design documentation. Work is created in co-operation with company ZDT Ltd.
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Návrh aplikační cisterny pro nosič výměnných nástaveb MEGA 33 / The application tanker for the trailer MEGA 33Koukal, Vojtěch January 2017 (has links)
This diploma thesis deals with conceptual design of application tanker for swap carrier MEGA 33. The first part of the thesis is focused on filling and emptying process possibilities, material alternatives used for the tankers manufacturing and evaluation of tankers with similar construction solution. The main part of this thesis describes conceptual design of tanker carrier. On the basis of this concept the stress analysis using finite element method has been completed. This thesis also includes relevant drawing documentation.
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Volba optimálního nástroje pro vybranou technologii obrábění / Selection of an optimal tool for the selected machining technologyPodstata, Jan January 2020 (has links)
This thesis compares the properties of four types of replaceable cutting tool inserts from different suppliers during milling. The comparative factors are cutting force, material loss of the insert and the roughness of the resulting surface. The thesis is divided into two parts - a comprehensive overview of the current state of knowledge and an experiment. The first part analyzes the load, the possibility of its measurement, surface treatment of tools, milling cutters and replaceable inserts. The experiment took the form of measuring the load during face milling, measuring the surface roughness of the machined material and measuring the material loss of the inserts on an optical strain gauge. The replaceable cutting tool inserts were compared based on the performed measurements.
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3D FDM tiskárna s výměnnou tiskovou hlavou / 3D FDM printer with a replaceable print headČuma, Zdeněk January 2021 (has links)
The aim of the work is to design and manufacture a mechanism for setting up and clamping the replaceable head of a 3D FDM printer. The first part of the thesis deals with 3D printing in general, the second part describes the FDM method. Part three is devoted to the selection and construction of a suitable 3D printer, the fourth part to the actual design of the head attachment. In the fifth part, a technical and economic evaluation is carried out.
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