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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

Study on Robust Control for a Flexible Beam

Su, Wei-Chih 23 July 2003 (has links)
The purpose of this paper is to study the design of robust control for a flexible beam. First, the finite element method (FEM) is used to formulate the ordinary differential equations (ODEs) of the dynamic system of the beam model, and a controller is designed via the H-inf control theory. From the computer simulation results, the following conclusions could be drawn. 1. The developed controller is capable of precision positioning and tolerating external disturbance. 2. The robust stability for the system is assured. Furthermore, robust control of linear one-dimensional systems is extended here to two-dimensional systems. The finite difference method (FDM) is applied to partial differential equations (PDEs) to obtain the so-called Roesser discrete state-space model. We discussed the application of H¡Û control for two-dimensional systems and the design of H-inf controller is formulated into a convex optimization problem characterized by linear matrix inequalities (LMIs). Finally, the solutions of the LMIs are then used to construct a two-dimensional H¡Û controller.
22

The effect of of clerodane diterpenoid 16-hydroxycleroda-3,13-dien-15,16-olide on colorectal cancer cell lines

Chen, Chiu-Roung 15 July 2008 (has links)
Polyalthia longifolia is a lofty evergreen tree found in India and Sri Lanka. Today, P. longifolia var. pendula is in large-scale cultivation in south Taiwan as a landscape plant. A new compound, clerodane diterpenoid 16-hydroxycleroda-3,13-dien-15, 16 -olide¡]CD¡^, was isolated from the bark of Polyalthia longifolia var. pendula. The compound was shown with cell growth inhibitory property at first screen in KMU¡]Kaohsiung Medical University¡^. In our study, antiproliferative activity of CD on human colorectal adenocarcinoma cells¡]HT29 and HCT116¡^were tested and the inhibitory concertration of 50¢Mcell viability¡]IC50¡^is 5 £gg/ml¡]HCT116¡^ and 10 £gg/ml¡]HT29¡^determined by MTT(3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. The caspase 3 and PARP cleavage experiment results indicated that CD induced apoptosis is dose dependent manner. We found that CD induced sub-G1 accumulation and reactive oxygen species(ROS) release by flow cytometry analysis. Pretreatment of N-Acetyl-L-cystine(NAC), an antioxidant agent, can reverse the anti-proliferation effect by CD. We found that CD induced loss of mitochondria membrane potentiol¡]£G£Zm¡^. We also analysis differentially expressed proteins by 2-D electrophoresis and find drug response proteins, e.g. HSP10, Profilin-1, Peroxindoxin-1. RT-PCR and western blot was performed to confirm the protein expression changes. It is interesting to reveal the role of these proteins in the colorectal cancinogenesis and anti-tumor drug response.
23

Analysis of Sp1 associated transcription regulatory factors bound on TSG101 promoter by DAPA and two dimensional gel electrophoresis

LIN, I-Ju 25 August 2008 (has links)
TSG101 is a tumor susceptibility gene exhibits multiple biological functions, including the regulation of vesicular trafficking, transcription, cellular growth and differentiation. The intracellular steady-state level of TSG101 was shown to under stringent control in a narrow range. Either deprivation or overexpression of mouse tsg101 in NIH3T3 cells leads to neoplastic transformation and subsequent tumorigenic potential of the transformed cells. However, the detail mechanism for regulation of TSG101 gene promoter activity is not clear. Our results indicated TSG101 is a housekeeping gene and contains a TATA-less and Sp1 binding site promoter. Here, we demonstrate in vivo binding of Sp1 transcription factor on TSG101 promoter region by chromatin immunoprecipitation(ChIP). In addition, Sp1-associated transcription regulators were purified using DNA affinity precipitation assay (DAPA) method and subjected to two-dimensional gel electrophoresis and the subsequent MALDI-TOF analysis. Our results verify the biding of Sp1 transcription on the DAPA probe containing wildtype but not the mutant Sp1 biding sequence by subsequent western blotting. Our MALDI-TOF analysis of protein spots from two-dimensional gel did not reveal the binding of Sp1 protein, instead the identified a number of cellular proteins, such as U5 small nuclear RNP¡BATP-dependent DNA helicase 2 and actin of unknown significance.
24

Development of a Single-Stage Modulator for Comprehensive Two-Dimensional Gas Chromatography (GC × GC)

McNeish, Christopher January 2011 (has links)
The ability to effectively analyze particulate matter (PM2.5) in air is becoming increasingly pertinent. Allen Goldstein of the University of California in Berkeley is studying the semi-volatile fraction of organic compounds in PM2.5 through the use of the thermal desorption aerosol gas chromatograph (TAG) system. However, as conventional GC does not provide adequate separation power, the development of comprehensive two-dimensional gas chromatography (GC × GC) was required. GC × GC works more effectively by utilizing a modulator that periodically traps and focuses analytes from a primary column onto a secondary column. This allows for the primary and secondary columns to separate the analytes based on two different properties. This report focuses on the continuing study and enhancement of a modulator designed by Ognjen Panić during his Masters project. Improving and testing the robustness of this dual stage modulator was originally the focus of this project. However, this study led to the development of a single stage modulator. In addition to that, the effect of modulator characteristics such as length of the restriction, total length of the modulator and wall thickness on the modulator performance were studied. A robustness test of the single stage modulator was also completed. Experiments conducted tested the characteristics of the new modulator to ensure it performed effectively and would satisfy the requirements of the TAG system. A study comparing the sensitivity of conventional gas chromatography and GC × GC was also preformed. The sensitivity of GC × GC was on average an order of magnitude better than that of 1D GC.
25

An investigation into the effect of lateral hillslope inputs on floodplain hydraulic model predictions

Charlton, Rosemary Anne January 1995 (has links)
In recent years there has been a growing interest in the contemporary floodplain environment which has come from a number of fields including civil engineering, hydrology, geomorphology and ecology. A major advance in civil engineering has been the development of two-dimensional hydraulic models capable of a high degree of spatial representation. These models were originally developed for engineering applications although recent developments, such as their application to longer reach lengths, mean that these models are very powerful predictive tools with potential for application in many different fields. Two-dimensional floodplain hydraulic models can be viewed as a platform for further development through the incorporation of additional components to represent specific processes. For the case of the application of these models in hydrology, whilst the models provide a good representation of floodplain processes in a hydraulic context, catchment hydrology is essentially treated as a black box. The only input to the system is the upstream input hydrograph (occasionally rainfall over the floodplain surface and tributary inflows are included) and output only occurs at the downstream boundary. The floodplain is assumed to be impermeable and any input from the hillslopes bordering the reach is ignored. This investigation examines the significance of contributions to the floodplain from the hillslopes bordering the reach. In order to do this, the zero flux boundary condition at the hillslope-floodplain interface is relaxed. A two-dimensional floodplain inundation model, RMA-2, is set up for a 14 km reach of the River Culm in Devon. A distributed hillslope hydrology model, VSAS3 is set up for a section of the hillslopes bordering the reach. This model is coupled to RMA-2 using a simple external coupling mechanism whereby water produced by VSAS3 is applied to elements along the edge of the RMA- 2 finite element mesh. A sensitivity analysis is carried out using this coupled scheme to identify some of the range of hillslope environments which may contribute a significant volume of lateral inflow to the floodplain. Five key hillslope parameters are selected and altered over a range of values. It has been shown that hillslope inflows can have a significant effect on the predictions made by RMA-2, both in terms of changes to the predicted output hydrograph and localised changes in depth and inundation extent. It has also been shown that the timing of the hillslope inflow peak relative to the arrival of the floodwave from upstream is of great importance. The addition of inflows has also been found to affect the calibration of the floodplain inundation model.
26

Eradication of Multidrug- Resistant Bacteria using Biomolecule-encapsulated Two-dimensional Materials

January 2019 (has links)
abstract: The increasing pervasiveness of infections caused by multidrug-resistant bacteria (MDR) is a major global health issue that has been further exacerbated by the dearth of antibiotics developed over the past 40 years. Drug-resistant bacteria have led to significant morbidity and mortality, and ever-increasing antibiotic resistance threatens to reverse many of the medical advances enabled by antibiotics over the last 40 years. The traditional strategy for combating these superbugs involves the development of new antibiotics. Yet, only two new classes of antibiotics have been introduced to the clinic over the past two decades, and both failed to combat broad spectrum gram-negative bacteria. This situation demands alternative strategies to combat drug-resistant superbugs. Herein, these dissertation reports the development of potent antibacterials based on biomolecule-encapsulated two-dimensional inorganic materials, which combat multidrug-resistant bacteria using alternative mechanisms of strong physical interactions with bacterial cell membrane. These systems successfully eliminate all members of the ‘Superbugs’ set of pathogenic bacteria, which are known for developing antibiotic resistance, providing an alternative to the limited ‘one bug-one drug’ approach that is conventionally used. Furthermore, these systems demonstrate a multimodal antibacterial killing mechanism that induces outer membrane destabilization, unregulated ion movement across the membranes, induction of oxidative stress, and finally apoptotic-like cell death. In addition, a peptide-encapsulation of the two-dimensional material successfully eliminated biofilms and persisters at micromolar concentrations. Overall, these novel systems have great potential as next-generation antimicrobial agents for eradication of broad spectrum multidrug-resistant bacteria. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019
27

Transport and Confinement in Bilayer Chiral Borophene

Albuhairan, Hassan 30 June 2021 (has links)
We employ a four-band continuum model to study the transport and confinement in an n-p-n junction in bilayer chiral borophene for both the identical- and oppositechirality configurations. The conditions for transport and confinement are elucidated in terms of the pseudospin. We study the transmission and reflection probabilities, conductances, and bound states. We demonstrate the existence of topological states in a domain wall between domains of opposite-chirality bilayer chiral borophene with reversed layer stacking. We find that changing the interlayer bias modifies the conductance of the identical-chirality configuration but not that of the opposite-chirality configuration, and that it induces a layer localization of the bound and topological states. Our findings suggest paths towards utilization of the layer degree of freedom in bilayer chiral borophene in future electronic devices.
28

Proteomic Analysis Of Listeria Monocytogenes

Mujahid, Sana 15 December 2007 (has links)
Listeria monocytogenes is a deadly, Gram-positive foodborne pathogen that is ubiquitous in the environment. The bacterium expresses a number of virulence and stress adaptation proteins that support its pathogenic capabilities. Two-dimensional gel electrophoresis (2-DE) was used to map L. monocytogenes surface proteins, which play a central role in virulence, and to examine protein expression by L. monocytogenes grown on ready-to-eat meat, an important source of Listeria infections. A novel method for solubilization of surface proteins from L. monocytogenes for 2-DE was developed. Additionally, the unique proteome expressed by L. monocytogenes grown on a meat matrix was uncovered. The developed solubilization method will facilitate efforts to identify and routinely compare surface proteins of Listeria by 2-DE. Furthermore, the 2-DE database of proteins expressed by L. monocytogenes grown on a meat matrix will allow further understanding of the interactions of Listeria with its food environment that influence its ability to cause disease.
29

A study of a two-dimensional electron system in the variable-range hopping regime

Hu, Xuelong January 1994 (has links)
No description available.
30

Calculating Geodesics on Surfaces

Burazin, Andrijana 04 1900 (has links)
<P> In this thesis, we mainly study geodesics on various two dimensional surfaces. All the background material needed throughout the thesis is provided, including an explanation of the theory of geodesics. We will calculate geodesics using two numerical methods: Euler's method and Runge-Kutta method of fourth order. Using Maple, we will test the accuracy of the numerical methods on a test case surface, the Poincare half plane. Later, we proceed to investigate several interesting surfaces by numerically calculating geodesics. From the investigated surfaces, we will draw similarities between the human cerebral cortex and certain surfaces. The human cerebral cortex is the most intensely studied part of the brain and it is believe that their exists a relation between the function and structure of the cortex. Geodesic analysis can possibly be an essential tool in better understanding the cortical surface as it is in many disciplines of science to understand the nature of physical based problems. </P> / Thesis / Master of Science (MSc)

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