Reliability Analysis of Continuous Structural Systems

This study mainly deals with developing another approximate method for system reliability analysis and its applications to the continuous structures such as an assembly of stiffened cylindrical and rectangular sections used in Tension Leg Platform (TLP). Various methods developed for the structural system reliability analysis are reviewed The developed system reliability method, called herein the "Extended Incremental Load Method", is an extended approach of the conventional incremental load method. It has been developed in order to extend its applicability to the system reliability analysis of a structure under multiple loadings. It directly uses existing component strength formulae in the system analysis and more realistically takes account of the post-ultimate (post-failure) behaviour of a failed component when assessing the system reliability and ultimate strength. This is an important merit of the method over other methods. The method allows for load re-distribution during the development of elasto-plastic moments in large cross-sections under the action of axial and bending forces and in the presence of lateral hydrostatic and hydrodynamic pressure. The effects of shearing actions are ignored. A search is made for the most important failure modes to give the lowest system safety index. In the method the modified safety margin equation, which has been proposed to use existing strength formulae for principle components of a floating offshore structure, is employed in which the strength modelling parameter is treated as a basic random variable in system reliability analysis as well as component reliability analysis and the concept of the first-order second moment method is adopted to obtain the resistance coefficients and the loading coefficients in the safety margin equation. Details about deriving the safety margin equation by the proposed reliability method, calculation of the total load factor, the procedure of identifying the most important failure modes and flow vectors of principle component are described in the Appendices. Applications to discrete structures are demonstrated to show the validity of the proposed method. The method has been applied to the Hutton TLP and two variants, TLP-A and TLP-B, which are modified models of the Hutton TLP and of the design using TLP Rule Case Committee type loading and improved strength models, under the design environmental loading conditions. Components and systems safety indices of the models, Hutton TLP, TLP-A and TLP-B, are illustrated with three dimensional collapse mechanisms figures. Reserve and reserve strength characteristics are derived for the design as built and for more economical and efficient variations of the design. The TLP form is shown to possess high redundancy and systems safety. Sensitivity studies to changes in stochastic parameters of resistance and loading variables have been carried out. For this purpose the strength modelling parameter, yield stress and certain member sizes are selected as resistance variables, and effects of their mean values and/or coefficients of variation on the system, as well as on the component reliability index, have been investigated. The effects of mean bias and coefficient of variation of load effects, namely, static, quasi-static and dynamic component, on the the system as well as on the component reliability index have also been investigated. The results are discussed with regard to effects of various parameters on safety, with illustrating figures, from which the relative importance of random variables can be seen. As an another important resistance variable, the post-ultimate behaviour of failed components has been taken account of in system reliability assessment, which should be the most important resistance variable affecting the system reliability and the effective residual strength of a structure. Some case studies have been carried out with the simplified non-linear model which has a form of piecewise multi-state (more than two states) and is characterised by the post-ultimate slope and the residual strength. The results are illustrated in figures and tables and discussion made about its effects on the system reliability level. (Abstract shortened by ProQuest.)

Real-time Atomic-resolution Probing of Lithium Ion Intercalation in TiO2-Related Anodes using Transmission Electron Microscopy.

Nanostructured TiO2 polymorphs such as rutile and bronze have been considered for lithium ion battery (LIB) application due to their chemical stability and accessibility. Despite their promising performance as anodes and coating materials, understanding of lithium ion behaviors in TiO2-related systems is still controversial, since most studies have relied on bulk characterization techniques which do not present local changes in morphology. Here, we employed in-situ transmission electron microscopy (TEM) and high-resolution scanning TEM (HRSTEM) to perform nano-scale structural studies of TiO2-related anodes upon Li intercalation. The electrochemical study of a single-crystalline rutile TiO2 nanowire (NW) was conducted under high-resolution TEM aided by selected area electron diffraction. The result demonstrates the two-step lithiation accompanied by the highly anisotropic volumetric expansion and phase transformation. An in-depth study of lithiation in bronze TiO2 (TiO2-B) had been possible by the growth of a high-quality TiO2-B thin film templated by Ca-modified bronze phase, CaTi5O11 (Ca:TiO2-B). Various interfaces and defects in TiO2-B and Ca:TiO2-B thin films deposited on (100) and (110) SrTiO3 substrates were first studied under HRSTEM. High crystallinity of (001) TiO2-B on a Ca:TiO2-B template motivated us to perform lithiation on the structure under HRTEM. Revealed by high-resolution observation of electrochemical lithiation into TiO2-B, many defects were induced by strain relaxation upon Li-induced TiO2-B lattice expansion. In fact, depending on Li intercalation direction into the structure, either high-symmetry structural transformation or plain shears was generated. The observations were corroborated by post-mortem HRSTEM characterization and theoretical calculation. The capability of a TiO2 nanostructure as a coating material for a LIB anode was also investigated via potentiostatic lithiation of a rutile TiO2-coated Si NW. It was found that lithium intercalation into this NW occurred locally by having each segment achieving full lithiation throughout the Li migration pathway. The TiO2 coating also influenced final lithiated morphology of a coated Si (Li15Si4) to be different from that of an uncoated one. The results discussed in this thesis provide the in-depth knowledge on the Li ion dynamics in two TiO2 polymorphs. The application of in-situ high-resolution TEM technique can be expanded towards other polymorphs of various different structural forms.PhDMaterials Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113420/1/sjkkorea_1.pd

South Korean Men and the Military: The Influence of Conscription on the Political Behavior of South Korean Males

This thesis evaluates the effects of compulsory military service in South Korea on the political behavior of men from a public policy standpoint. I take an institutional point of view on conscription, in that conscription forces the military to accept individuals with minimal screening. Given the distinct set of values embodied by the military, I hypothesize that the military would need a powerful, comprehensive, and fast program of indoctrination to re-socialize civilians into military uniform, trustable enough to be entrusted with a gun or a confidential document. Based on the existence of such a program and related academic literature, I go on to look at how a military attitude has political implications, especially for the security-environment of the Korean peninsula. Given the ideological nature of the inter-Korean conflict, the South Korean military was biased against the liberals, as liberals were most likely to generate policies supporting conciliatory and cooperative measures towards North Korea, like the removal of U.S. forces from South Korea and the repeal of the National Security Laws that outlaw discussion of communism. For an empirical evaluation, I pose the hypothesis that this political bias would manifest itself in the male public via the military’s indoctrinative program. With data from the Korean General Social Survey, the Public Opinion and Foreign Policy, and the South Korean General Election Panel Study, I have found that males respond acutely to specific security issues in favor or against according to the military’s point of view. However, the evidence for an overall bias on political parties generally was inconclusive. The uncertainty was mainly rooted in the fact that liberal parties have strategically avoided speaking out on specific policy issues during election

Shape design optimization of parametric flume sections.

This research presents a shape design analysis and optimization methodology for parametric surface flume sections. Flume sections or flow channels have been used widely in many areas such as water chutes in civil and agricultural engineering and water slides and bob sled tracks in the recreational and sports fields. Designing such a flow channel in a CAD environment can provide many advantages such as time and resource savings to the designer. In addition, optimizing such flow channels in a virtual environment is especially efficient.In this research, geometric modeling was addressed first. Two types of parametric surface flume section models were created: B-Spline-based flume sections and parametric CAD-based flume sections as used in water chutes or water slides. The B-Spline-based flume sections were based on the dimensions of fifteen flume sections, provided by a commercial water slide firm. These flume sections presented the basis for building up realistic flume section configurations. In addition, three different kinds of CAD-based flume sections were developed by the author. Sets of differential equations based on Lagrange's equations of motion were derived that describe the motion of an object traveling in the flow channel. These ordinary differential equations were solved using MathematicaRTM. Continuity requirements were derived from the equations of motion. An analytical shape design sensitivity analysis (DSA) methodology was developed and employed to support the optimization of the B-Spline-based and the CAD-based flume section models.Optimization of parametric surfaces is a reasonably new area. Although research has been done in this area, most of it has been focused on developing better parametric surfaces, i.e., surface fitting schemes. Here, the B-Spline-based models, based on bi-cubic B-Spline surfaces, were optimized first. The control point positions were used as design variables in the optimization. Using the B-Spline control points as design variables provides more flexibility and allows for local design changes. However, the fact that no CAD software provides the control points as design parameters significantly limits their usefulness in a real design environment. The CAD-based flume section models consisted of sets of key dimensions, which were again defined as design variables for optimization. Using dimensions as design variables provided an easy and realistic avenue for design changes. However, the limited number of dimensions also limits the flexibility of design changes in the CAD-based flume section models. (Abstract shortened by UMI.

The flavonoid luteolin prevents lipopolysaccharide-induced NF-kappaB signalling and gene expression by blocking IkappaB kinase activity in intestinal epithelial cells and bone-marrow derived dendritic cells

The nuclear factor (NF)-κB transcriptional system is a major effector pathway involved in inflammation and innate immune responses. The flavonoid luteolin is found in various herbal extracts and has shown anti-inflammatory properties. However, the mechanism of action and impact of luteolin on innate immunity is still unknown. We report that luteolin significantly blocks lipopolysaccharide (LPS)-induced IκB phosphorylation/degradation, NF-κB transcriptional activity and intercellular adhesion molecule-1 (ICAM-1) gene expression in rat IEC-18 cells. Using chromatin immunoprecipitation, we demonstrate that LPS-induced RelA recruitment to the ICAM-1 gene promoter is significantly reduced in luteolin-treated cells. Moreover, in vitro kinase assays show that luteolin directly inhibits LPS-induced IκB kinase (IKK) activity in IEC-18 cells. Using bone-marrow derived dendritic cells (BMDCs) isolated from interleukin (IL)-10−/− mice or from recently engineered transgenic mice expressing the enhanced green fluorescent protein (EGFP) under the transcriptional control of NF-κB cis-elements (cis-NF-κBEGFP), we found that luteolin blocks LPS-induced IκB phosphorylation and IKK activity, and decreases EGFP, IL-12 and tumour necrosis factor-α gene expression. Moreover, intraperitoneal administration of luteolin significantly inhibited LPS-induced EGFP expression in both peripheral blood mononuclear cells and splenocytes isolated from cis-NF-κBEGFP mice. These results indicate that luteolin blocks LPS-induced NF-κB signalling and proinflammatory gene expression in intestinal epithelial cells and dendritic cells. Modulation of innate immunity by natural plant products may represent an attractive strategy to prevent intestinal inflammation associated with dysregulated innate immune responses

The Effect of Personality Characteristics and Organizational Culture on Service Emotional Labor

This study analyzed data from 328 emotional workers to examine how personality traits and organizational culture affect emotional labor. Extraversion (CR value – 3.078, *** ρ < .001), agreeableness (CR value 2.135, * ρ < .05), and neuroticism (CR value 2.557, * ρ < .05) are significant in surface acts of emotional labor. The results showed that conscientiousness (CR value 1.761) and openness (CR value -0.55) were not significant. In internal behavior, extraversion (CR value 3.771, *** ρ < .001) and openness (CR value 3.216, ** ρ < 0.1) appeared significantly, while agreeableness (CR value -1.42) and conscientiousness (CR value 0.322)), neuroticism (CR value –0.324) was not significant