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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.
81

Degradation of Shear Performance of Beams due to Bond Deterioration and Longitudinal Bar Cutoffs

Masukawa, Junji 30 August 2012 (has links)
Experimental and analytical research has been conducted to investigate the degradation of shear performance of beams due to bond deterioration and longitudinal bar cutoffs. To achieve the controlled rate of bond degradation, the method of adjustment of the rib height by machining was adopted. Bond behaviour of the milled bars were measured in tension stiffening tests with internally installed strain gauges. Maximum bond stresses for the milled bars were reduced by up to 50% compared to those for normal deformed bar. The bond behaviour of the milled bars were compared with those of the bars subjected to accelerated corrosion. It was confirmed that the stripped bar had the possibility to simulate corroded bars to some extent. Based on the calculations of average tensile stresses in the cracked concrete for each specimen, appropriate tension stiffening factors for each type of bar were suggested and then verified with the 2-dimensional nonlinear finite element analysis program VecTor2. Next, eight simply supported beams were tested. In four of them half of the longitudinal bars were cut off near the supports. Various combinations of normal and machined reinforcing bars were selected for both longitudinal and transverse reinforcement. The predicted shear failure load for the cutoff beam based on the general method for shear design in CSA A23.3-04 was unconservatively estimated. Cutoffs of longitudinal reinforcement resulted in much more significant drops of shear resistance than did bond deterioration of reinforcement. The inclinations of diagonal cracks for the cutoff series were larger than those for the no-cutoff series due to significant concentrations of longitudinal strains near the cutoff locations. Finally modifications to the general shear design method in CSA A23.3-04 were proposed based on the results of VecTor2 analyses for the beam tests. It was found that the influence of bond deterioration on the shear strength of reinforced concrete member can be accounted for by adjusting the tension stiffening factor applied to the equation for β. With respect to bar cutoffs, its influence on shear strength can be expressed by the strain concentration factor applied to the equation for ε_x.
82

Profitability of butterfly trades in bond markets

Pal, Satyajit, Banking & Finance, Australian School of Business, UNSW January 2007 (has links)
The Efficient Market Hypothesis (EMH) has had significant impact on the theory and practice of investments. However technical trading rules have continued to be used by practioners and have been the focus of many academic studies which have focused on equity, foreign exchange and futures markets. The scarcity of research into technical trading models for fixed income markets is astonishing considering the significant size and consequent investor importance of fixed income markets relative to other financial markets and the extensive application of technical trading models by market participants. This is one of the few studies that develops a technical trading model applicable to fixed income markets. Black (1986) defined Efficient Markets as a market where deviations from fundamental values were short lived and small in magnitude. Fundamental asset values are hard to calculate, but we are able to identify fundamental values for a set of Government Bonds on the principle that yield relativities between such bonds are quite stable except for 'deliberate' changes in trading behaviour. We find that the deviations from fundamental value are short lived and small in magnitude. We exploit deviations from fundamental value by Butterfly Trading strategies; Normal Butterfly trades earning returns from movements in yield curve slope and curvature and Arbitrage Butterfly trades earning returns from yield curve curvature only. After considering transaction costs, we achieve annualised returns of 120bps from our Normal Butterfly trades and 72 bps from our Arbitrage Butterfly trades. Consistent with the risk-return relationship for financial instruments, we find that the returns and the volatility of returns for Normal Butterfly trades are higher than the returns and volatility of returns for Arbitrage Butterfly trades. Normal Butterfly trades are exposed to yield curve slope changes whereas Arbitrage Butterfly trades are not, resulting in higher risk and higher returns for Normal Butterfly trades. This finding is consistent with the results obtained by Fabozzi, Martellini and Priaulet (2005).
83

Der Bericht des Herzogs Ernst II. von Koburg über den Frankfurter Fürstentag 1863 ...

Dorien, Kurt, January 1910 (has links)
Inaug-diss.--Greifswald. / Lebenslauf.
84

An in vitro study of composite repair

Mohammed, Hesham January 2007 (has links)
Magister Scientiae - MSc / The aim of this study is to investigate the repair bond strength of composite resin following micromechanical and chemical means of retention in improving the repair of composite resin specimens.
85

The effects of dentine contamination on the shear bond strength of a self-etching adhesive and a nanocomposite

Soni, Vishani January 2017 (has links)
This research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Dentistry. School of Oral Health Science, Faculty of Health Sciences, University of the Witwatersrand, South Africa Johannesburg, 2017 / Purpose: Resin restorative materials have improved over the years. A major obstacle to the acquisition of acceptable bond strength of bonding agents is the presence of contaminated dentine cavity preparations. The purpose of this study was to investigate the effects of oral contaminants such as blood, saliva and a disinfectant contamination on the shear bond strength of a nanocomposite on a self-etching adhesive system. Materials and Methods: Thirty-six caries free premolar teeth were extracted and placed in a disinfectant solution containing 0.5 % Chloramine T solution, and then randomly distributed into four groups. Each tooth was then placed into a stainless steel ring supported by clear self-curing acrylic. They were thereafter immersed into a saline solution of 37 ̊C - 37.5 ̊C in an incubator for 24 hours. The enamel surfaces of the premolars were then ground with a Pro-trim 1725 Hertz grinder using 600 grit silicon carbide fine grinding paper to expose the dentine surface of each tooth. The sample was then re-immersed in the saline solution and incubated at 37°C - 37.5°C. The teeth were then arranged into the four groups: Group 1 (control group); Group 2 (human blood contamination at 5 seconds); Group 3 (human saliva contamination at 5 seconds) and Group 4 (chlorine dioxide contamination at 5 seconds). A self-etching adhesive bonding system (Scotchbond universal™) and Filtek supreme XTE composite was applied to the exposed dentine surface. Samples were randomised and then sheared using an Instron testing machine to determine their bond strengths. The fractured components of each sample were measured, compared and further examined under a stereo microscope to determine the modes of failure. The data were analysed using a one-way analysis of variance (ANOVA) and the level of significance was set at a p-value of less than 0.05. Results: A significant difference was found in the shear bond strength between the control (group 1) and the blood contaminated group (group 2) (p-value of 0.00064). The chlorine dioxide group (group 4) that had no effect on shear bond strength to dentine (p-value of 0.55). Adhesive failures (between bonding agent and dentine) were predominant in group 2 and to a lesser extent in group 3. Most group 4 samples had cohesive fractures (within the dentine). Conclusion: The bond strength to dentine using a self-etching adhesive was reduced when contaminated with blood. Group 2 samples (blood) caused significantly greater bonding failure as compared to all the other groups. Chlorine dioxide solution is a powerful disinfectant and does not affect the bonding to dentine. The null hypothesis statement, which stated that there was no difference in the shear strength between any of the conditions, was thus rejected. Further studies on the application of chlorine dioxide as a disinfectant on cavity preparations need to be considered given the surprising positive results of chlorine dioxide group. / MT2018
86

The Sulphur Nitrogen Bond 1. Lewis Acid Adducts of Tetrasulphur Tetranitride 2. Reaction of Sulphur with dl-α-Methylbenzylamine

Chan, Cheong Hoi 10 1900 (has links)
<p> Adducts of aluminum chloride and aluminum bromide with tetrasulphur tetranitride have been prepared and characterized. The reaction of trimethylaluminum and triethylaluminum with tetrasulphur tetranitride has been studied. The reaction of sulphur with α-methylbenzylamine has been investigated, and the reaction mechanism proposed by Sasaki for benzylamine reacting with sulphur has been found to be consistent with the data, provided certain limitations are imposed. </p> / Thesis / Master of Science (MSc)
87

Understanding the mother-infant bond

Milne, Elizabeth J.M., Johnson, Sally E., Waters, Gillian M., Small, Neil A. 09 1900 (has links)
No / Abridged version of article Milne E, Johnson SE, Waters GM et al (2018) The mother-infant bond: a systematic review of research that includes mothers’ subjective experience of the relationship. Community Practitioner. Accepted for publication.
88

Svolatelné dluhopisy, využití a oceňování / Callable bonds and its use and valution

Ledvina, Jan January 2011 (has links)
Callable bond is a type of bond which allows an issuer to redeem its bonds prior to maturity for specified price. Such a type of bond is very rare in Czech Republic. This scarcity is caused by undeveloped domestic bond market and also by domestic investors being conservative, preferring guaranteed income. Callable bond does not offer such certainty in cash flow. Therefore the aim of this diploma thesis is to provide a complex view on callable bonds, which is hitherto absent in Czech literature. This thesis starts with introduction of the general terms related to callable bonds. In the subsequent chapter, various uses of callable bonds follow. The third part analyses the biggest callable bond market in the world -- the US callable bond market -- and characterizes every particular sector of the market. The last part of the thesis deals with callable bonds' valuation and its advanced analytical measures that are constructed in connection with valuation models.
89

Legitimizing Disclosures in an Anomic Environment: An Examining of Citigroup's $13 Billion Euro-Bond Short Sale

Fiorentino, Angelica 01 January 2007 (has links)
On August 2, 2004, Citigroup traders based in the UK sold short more than $13 billion worth of government bonds only to buy them back seconds later at a profit of about $18.2 million dollars. This strategy was carefully planned, the consequences acknowledged by key participants, and it was profitable to the serious detriment of other market participants. The event is ethically questionable because it violates the spirit of European regulation. The purpose of this study is to investigate disclosures made by and about Citigroup surrounding a regulatory investigation into this short-sale within the contexts of legitimacy and institutional anomie theories.
90

Green Debt Financing : Examining Investors’ Reactions to Green Bond Announcements in Europe

Hussmann, Lena, Simonsson, Filip January 2022 (has links)
This paper examines what effects announcements of green bond issuances have on publicly traded firms’ stock prices in Europe. Signalling theory is used in line with suggestions from previous research to investigate potential abnormal returns. Using a dataset of 432 green bond issuances from 165 unique publicly traded firms on European stock exchanges, we conduct an event study around the announcement day [0,1] estimating abnormal returns using the market model. To further investigate determinants of abnormal returns we conduct a multiple linear regression analysis. We document no statistic or economic significant effect in our full sample. Only first-time issuances of green bonds have a significant abnormal return of 0,74% in the period after announcement but show no significant results on the announcement date. Green bonds being a credible signal of environmental commitment thus has inconclusive support in our study and equity investors seem largely indifferent to firm’s green bond announcements.

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