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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.
461

Theory and Applications of Multiconductor Transmission Line Analysis for Shielded Sievenpiper and Related Structures

Elek, Francis 15 February 2011 (has links)
This thesis focuses on the analytical modeling of periodic structures which contain bands with multiple modes of propagation. The work is motivated by several structures which exhibit dual-mode propagation bands. Initially, transmission line models are focused on. Transmission line models of periodic structures have been used extensively in a wide variety of applications due to their simplicity and the ease with which one can physically interpret the resulting wave propagation effects. These models, however, are fundamentally limited, as they are only capable of capturing a single mode of propagation. In this work multiconductor transmission line theory, which is the multi-mode generalization of transmission line theory, is shown to be an effective and accurate technique for the analytical modeling of periodically loaded structures which support multiple modes of propagation. Many results from standard periodic transmission line analysis are extended and generalized in the multiconductor line analysis, providing a familiar intuitive model of the propagation phenomena. The shielded Sievenpiper structure, a periodic multilayered geometry, is analyzed in depth, and provides a canonical example of the developed analytical method. The shielded Sievenpiper structure exhibits several interesting properties which the multiconductor transmission line analysis accurately captures. It is shown that under a continuous change of geometrical parameters, the dispersion curves for the shielded structure are transformed from dual-mode to single-mode. The structure supports a stop-band characterized by complex modes, which appear as pairs of frequency varying complex conjugate propagation constants. These modes are shown to arise even though the structure is modeled as lossless. In addition to the periodic analysis, the scattering properties of finite cascades of such structures are analyzed and related to the dispersion curves generated from the periodic analysis. Excellent correspondence with full wave finite element method simulations is demonstrated. In conclusion, a physical application is presented: a compact unidirectional ring-slot antenna utilizing the shielded Sievenpiper structure is constructed and tested.
462

Discrete event modelling and Simulation of an Assembly Line at GKN Driveline Köping AB

Yesilgul, Mustafa, Nasser, Firas January 2013 (has links)
Today’s economic conditions force companies and organizations to work more effectively in their processes due to different reasons.  Especially; after the Second World War, owing to the changing business perception and strong competition between companies, new terms such as productivity, flexible systems, efficiency, and lean came into industrial engineering discipline. However, these kinds of terms also brought a new question. How are they reached?  At that point, discrete event simulation has been used as an effective method to give an answer to this question. From this perspective; this project focuses on discrete event simulation and its role in real industrial processes. The main interest of this paper is discrete event simulation, but in this study we also tried to give some detailed information about other types of simulations such as continuous and discrete rate. Basically, we can say that this paper consists of several parts. In the beginning of this paper, the reader can find some theoretical information about simulation itself and the requirements for implementing it on real processes. Secondly, we tried to explain different types of simulations and the reason why we used discrete event simulation instead of continuous or discrete rate in our case study. Furthermore, one of the main areas of this research is to inform the reader about how computer support is used as a simulation tool by today’s companies. To do this, a powerful software, Extendsim8, is described in detail.  The reader is able to find all the information about how to create discrete event models in this software. In case study part, we are able to find the results of the five months work that we did between February and June at GKNDriveline Köping AB in Sweden. In these five months, we had been busy with analyzing an assembly line, collecting data, creating a simulation model, discussion with workers and engineers and doing some tests such as validation & verification. In this part, the reader can find all the information about the production line and the simulation model. In conclusion, reader can find the results of the project at the end with the visualization of future state. As it will be discussed repeatedly in the paper, validation is one of the important steps in a simulation project. Therefore, in order to see the reliability of our simulation model, different calculations and tests were made. Last of all, some of results will be shown by graphs and tables in order to give better insight to reader.
463

Developing and characterizing a salmonid intestinal epithelial cell line for use in studies of inflammation in the fish gastrointestinal tract

Kawano, Atsushi January 2009 (has links)
An intestinal cell line from rainbow trout, Oncorhynchus mykiss, was developed and challenged against several bioactive components. Primary cultures initiated from the distal segment produced the cell line, RTgutGC. RTgutGC showed optimal growth in L15 supplemented with 10-20% fetal bovine serum (FBS) at room temperature. RTgutGC has undergone over 100 passages and stained minimally for β-galactosidase, suggesting this to be an immortal cell line. Late passage cultures gave a consistent polygonal morphology with distinct borders. RTgutGC stained positive for alkaline phosphatase (AP) under certain culture conditions, hence may produce intestinal-specific alkaline phosphatase (IAP). Lipopolysaccharide (LPS) was used as a model microbial endotoxin for determining the sensitivity of the cells to a natural ligand in the gastrointestinal tract (GIT). Exposure of LPS was compared between RTgutGC and two mammalian intestinal cell lines (HT-29 and Caco-2). LPS induced cell death in RTgutGC, potentially through an alternative pathway seen in higher vertebrate response. Cytotoxicity of LPS against RTgutGC, seeded at normal density, was reduced in the presence of glutamine compared to L15 alone (t test, p≤ 0.05). RTgutGC seeded at a super density, where AP was strongly expressed, also showed less toxicity towards LPS. Two isoforms of tumor necrosis factor alpha (TNF-α) transcripts were up-regulated after LPS treatment in RTgutGC. Six rainbow trout cell lines, including RTgutGC, showed constitutive transcript expression of several immune-related genes: Major Histocompatibility (MH) class II α and ß. When MH activity was examined at the protein level, the cell lines showed constitutive expression of MH class I proteins, but not for MH class II molecules. RTS11, a rainbow trout spleen monocyte/ macrophage-like cell line, was the only line to express all MH transcripts and proteins. The utility of the anti-rainbow trout MH protein sera was demonstrated by exposing RTgutGC to poly IC. After a 3 day treatment, RTgutGC showed up-regulation of β2m protein expression. Thus, the cellular and immunological responses in fish intestinal cells can be modeled using the methods presented in this study.
464

The overhead line sag dependence on weather parameters and line current

Lindberg, Elisabeth January 2011 (has links)
As the demand for energy increases, as well as the demand for renewable energy, Vattenfall, as network owner, receives many requests to connect new wind power to the grid. The limiting factor for how much wind power that can be connected to the grid is in this case the maximum current capacity of the overhead lines that is based on a line temperature limit. The temperature limit is set to ensure a safety distance between the lines and the ground. This master thesis project is a part of a research project at Vattenfall Research and Development that is examining the possibilities of increasing the allowed current on overhead lines in order to be able to connect more wind power to the existing network. Measured data from two overhead lines in southern Sweden is analyzed and the internal relations between the measured parameters are examined. The measured parameters are overhead line sag, line temperature, ambient temperature, solar radiation, wind speed and line current. The results indicate that there is a big load margin that could be utilized to increase the maximum current as long as further work could show that low winds at line height correlates with low wind at nacelle height. The results show that the sag versus line temperature is approximately linear within the measured temperature range. This means that a real-time-monitoring system measuring the line temperature should give adequate knowledge of the line position to ensure the safety distance. A model for the line temperature as a function of insolation, current, ambient temperature and wind speed has been estimated for one of the lines. Simulations show that a sudden increase in current at a worst-case scenario would give the operators about ten minutes to react before the line reaches the temperature limit.
465

Developing and characterizing a salmonid intestinal epithelial cell line for use in studies of inflammation in the fish gastrointestinal tract

Kawano, Atsushi January 2009 (has links)
An intestinal cell line from rainbow trout, Oncorhynchus mykiss, was developed and challenged against several bioactive components. Primary cultures initiated from the distal segment produced the cell line, RTgutGC. RTgutGC showed optimal growth in L15 supplemented with 10-20% fetal bovine serum (FBS) at room temperature. RTgutGC has undergone over 100 passages and stained minimally for β-galactosidase, suggesting this to be an immortal cell line. Late passage cultures gave a consistent polygonal morphology with distinct borders. RTgutGC stained positive for alkaline phosphatase (AP) under certain culture conditions, hence may produce intestinal-specific alkaline phosphatase (IAP). Lipopolysaccharide (LPS) was used as a model microbial endotoxin for determining the sensitivity of the cells to a natural ligand in the gastrointestinal tract (GIT). Exposure of LPS was compared between RTgutGC and two mammalian intestinal cell lines (HT-29 and Caco-2). LPS induced cell death in RTgutGC, potentially through an alternative pathway seen in higher vertebrate response. Cytotoxicity of LPS against RTgutGC, seeded at normal density, was reduced in the presence of glutamine compared to L15 alone (t test, p≤ 0.05). RTgutGC seeded at a super density, where AP was strongly expressed, also showed less toxicity towards LPS. Two isoforms of tumor necrosis factor alpha (TNF-α) transcripts were up-regulated after LPS treatment in RTgutGC. Six rainbow trout cell lines, including RTgutGC, showed constitutive transcript expression of several immune-related genes: Major Histocompatibility (MH) class II α and ß. When MH activity was examined at the protein level, the cell lines showed constitutive expression of MH class I proteins, but not for MH class II molecules. RTS11, a rainbow trout spleen monocyte/ macrophage-like cell line, was the only line to express all MH transcripts and proteins. The utility of the anti-rainbow trout MH protein sera was demonstrated by exposing RTgutGC to poly IC. After a 3 day treatment, RTgutGC showed up-regulation of β2m protein expression. Thus, the cellular and immunological responses in fish intestinal cells can be modeled using the methods presented in this study.
466

Generating Graphical User Interfaces for Software Product Lines: A Constraint-based Approach

Müller, Johannes 12 March 2012 (has links) (PDF)
Due to a high competitive pressure on the global software market, in many areas the software industry is moving from hand crafting to semi-automatic or automatic software construction based on Software Product Lines (SPL). Techniques to automate the construction of software products from SPLs are widely available. These can handle variability in source code artifacts but they are inappropriate to handle variability in Graphical User Interfaces (GUIs). The main reason is that they are not designed to handle such fine grained configurations as they are required to configure GUI frameworks or toolkits. To nevertheless employ them in GUI generation tasks is complex and time consuming. However, in the Human Computer Interaction (HCI) community approaches to develop GUIs in a model-based manner and with constraint-based techniques are worked on that help automate the construction of GUIs. Therefore, the main hypothesis of the proposed research is that constraint-based GUIs techniques are a well suited basis for reducing the customization effort of generated GUIs of SPLs. The paper proposes a research plan to employ these new HCI techniques in generating GUIs for SPLs.
467

PI Control of Gene Expression in Tumorous Cell Lines

Mendonca, Rouella J. 16 January 2010 (has links)
Recent experiments are bringing to the fore more and more information about the effects of different treatments on the gene expression of different genes. The results obtained from these experiments show that some definite trends are observed in different genes in the Human Embryonic Kidney and Human Colon Adenocarcinoma Grade II cell lines. The difference in the gene expressions of the two cell lines motivates the problem in this thesis. The thesis provided intervention methods to make the colon cancer cell line genes behave more like their Human Embryonic Kidney cell line counterparts. Two methods of intervention were introduced. The first method was the simpler on-off control intervention while the second method used a more advanced proportional integral control to meet the goal. A comparison of these two intervention methods showed the clear implementational advantages of proportional integral control over on-off control.
468

Nondestructive Testing of Overhead Transmission Lines: Numerical and Experimental Investigation

Kulkarni, Salil Subhash 2009 December 1900 (has links)
Overhead transmission lines are periodically inspected using both on-ground and helicopter-aided visual inspection. Factors including sun glare, cloud cover, close proximity to power lines and the rapidly changing visual circumstances make airborne inspection of power lines a particularly hazardous task. In this research, a finite element model is developed that can be used to create the theoretical dispersion curves of an overhead transmission line. The complex geometry of the overhead transmission line is the primary reason for absence of a theoretical solution to get the analytical dispersion curves. The numerical results are then verified with experimental tests using a non-contact and broadband laser detection technique. The methodology developed in this study can be further extended to a continuous monitoring system and be applied to other cable monitoring applications, such as bridge cable monitoring, which would otherwise put human inspectors at risk.
469

Research on electrical performance of differential pair design in package substrate

Huang, Chih-yi 18 July 2007 (has links)
Differential signaling is suitable for high speed signal transmission due to lower noise induction and higher common-mode noise rejection compared to its single-ended signaling counterpart. However, for a high performance differential transmission-line pair, excellent symmetry and appropriate design for substrate layer stack-up is necessary. Especially for a practical IC package substrate, differential transmission-line pair is inevitable for asymmetry because of considering the locations of IC pads and solderballs. Furthermore, different differential transmission-line pair architectures are also demanded in consideration of limited substrate floorplan space and substrate layer stack-up structures. In this thesis, several differential pairs have been implemented on the conventional 4-layer laminate package substrate. The consequent high frequency performances are measured using vector network analyzer and then compared by converting into mixed-mode S-parameters.
470

Role of the Differentiation-Associated Intracellular Glutathione Contents and Oxidative Stress Status on the Regulation of Erythropoietin Gene Expression in Human Hepatocellular Carcinoma cell lines.

Lo, Wei-Ching 09 July 2002 (has links)
Erythropoietin (EPO) is produced in the kidney and in fetal liver in response to hypoxia as well as to CoCl2. The EPO protein and mRNA can be induced in response to both stimuli in the human hepatoma cell (HCC) lines Hep 3B and Hep G2. An oxygen sensing mechanism in which a ligand dependent conformational change in the heme protein produces H2O2 in respone to either hypoxia or Cobalt has been demonstrated. However, an intriguing question can be raised as to why some HCC sublines, such as Hep G2 and Hep 3B are capable of expressing EPO gene, whereas in other HCC sublines, such as J5 and SK-Hep-I are completely devoid of the ability to express EPO gene. Along this line, does ¡§differentiation status¡¨ of these HCC cells play a pivotal role in regulating the expression of EPO gene? Next in line, how a differentiation-associated upregulation of g-glutemylcysteine synthetase (g-GCS), which tightly regulating the biosynthesis of endogenous glutathione(GSH) can modulate the expression of EPO. The objective of this research project was designed to address all these questions. Reported herein are several lines of evidence to demonstrate that endogenous GSH contents do play a pivotal role in the control and regulation of the expression of EPO gene. Firstly, using a group of five HCC lines with varying degrees of differentiation as the experimental model, we demonstrated that the endogenous GSH contents of these HCC cells were differentially upregulated depending on the degree of differentiation with an order of abundance being Hep G2> Hep 3B> J5> Mahlavu> SK-Hep-I. Coincidently, we also found that g-GCS heavy subunit activities as well as its mRNA correlated precisely with this order. Among these HCC cell lines tested, only two well-differentiated sublines, Hep G2 and Hep 3B expressed EPO gene implying that the latter process was dependent upon GSH and suggested a notion that a threshold level might be required for its optimal reactivation. Secondly, to further obtain the evidence to substantiate this possible role of GSH, we then supplemented to the cell culture media with an excessive quantity of nonlethal N-acetylcysteine for the purpose of reinforcing the endogenous GSH biosynthesis. Interestingly, we found that this manipulation could revert the reactivation of EPO gene in cell lines, such as J5 and SK-Hep-I, in which their EPO gene expressions were ortherwise shut down under a normal circumstance. Finally, we were able to demonstrated using RT-PCR and western blotting that the expression of EPO gene was reverted in GCS30, a SK-Hep-I subline that was permanently transfected with g-GCSh and is capable of overly expressing endogenous GSH. Taken together, we demonstrated herein for the first time that, besides hypoxia and CoCl2, endogenous GSH contents can also act as a positive regulator for the expression of EPO gene. The underlying mechanism of how GSH exerts its action in the regulation of EPO expression awaits further clarification.

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