Global and local performance of prestressed girder bridges with positive moment continuity detail

Global as well as local behavior of prestressed girder bridges made continuous by adding continuity diaphragms with a recently proposed positive moment continuity detail were investigated in this study. The focus of the investigation is on the positive moment caused by temperature gradients, time dependent effects such as creep and shrinkage, and some live load positions, and on the force transfer mechanisms through the diaphragm. The study utilized different approaches including analytical models for temperature evaluations and finite element models for structural assessments. Field data from a bridge using the new detail were used to validate the developed models. The temperature field of the bridge at different times of the year was estimated using an analytical method. The computed temperature profiles, actual recorded temperatures at the bridge site, and AASHTO specified design gradients are presented and compared. Primary as well as secondary thermal stresses were calculated and restraint moment caused by temperature gradient was quantified. A 3-D finite element model capable of predicting the long term behavior of prestressed girder bridges is presented. A temperature independent creep model was adopted and calibrated using early age data. Construction sequence was considered in the analysis. The FE restraint moment predictions were compared to results obtained from other commonly used analytical method. A parametric study was conducted using the analytical method to investigate the creep coefficient values. Performance of the continuity detail under live load effects was investigated. A live load test was carried out at the bridge site using two loaded trucks. A full bridge 3-D finite element model was also developed and validated with the field data. The validated FE model was also used to investigate the efficiency of the continuity detail. A more detailed 3-D FE model that zooms in on the joint was also built accounting for critical behavioral aspects of the continuity details under service conditions. Contact between cast-in-place concrete and precast concrete, transfer length of prestressing strands, and actual 180º-hook hairpin bar detail were included in the detailed model. Force transfer mechanism, stress distribution and the effective gross moment of inertia at end of girder were investigated

Free-Surface Wall-Jet Flow at Moderate Reynolds Number as Applied to Slot and Blade Coating

The flow of a two-dimensional steady wall jet observed in the slot and blade coating processes has been examined theoretically near the channel exit. The Newtonian free surface jet emerges from a channel and deposits onto an infinite moving wall with an adverse or favorable pressure gradient applied inside the channel. The Reynolds number considered is within the moderate range, and fully developed Couette-Poisueille flow conditions are assumed to prevail far upstream inside the channel. The effects of inertia and pressure gradient on the velocity, the shape of the free surface, and the stress are emphasized. It is found that the jet always contracts near the channel exit regardless of the level of inertia and direction of the applied pressure gradient. An adverse pressure gradient provides thinner film thickness than a favorable one

Forecasting seasonal hydrologic response in major river basins.

Seasonal precipitation variation due to natural climate variation influences stream flow and the apparent frequency and severity of extreme hydrological conditions such as flood and drought. To study hydrologic response and understand the occurrence of extreme hydrological events, the relevant forcing variables must be identified. This study attempts to assess and quantify the historical occurrence and context of extreme hydrologic flow events and quantify the relation between relevant climate variables. Once identified, the flow data and climate variables are evaluated to identify the primary relationship indicators of hydrologic extreme event occurrence. Existing studies focus on developing basin-scale forecasting techniques based on climate anomalies in El Nino/La Nina episodes linked to global climate. Building on earlier work, the goal of this research is to quantify variations in historical river flows at seasonal temporal-scale, and regional to continental spatial-scale. The work identifies and quantifies runoff variability of major river basins and correlates flow with environmental forcing variables such as El Nino, La Nina, sunspot cycle. These variables are expected to be the primary external natural indicators of inter-annual and inter-seasonal patterns of regional precipitation and river flow. Relations between continental-scale hydrologic flows and external climate variables are evaluated through direct correlations in a seasonal context with environmental phenomenon such as sun spot numbers (SSN), Southern Oscillation Index (SOI), and Pacific Decadal Oscillation (PDO). Methods including stochastic time series analysis and artificial neural networks are developed to represent the seasonal variability evident in the historical records of river flows. River flows are categorized into low, average and high flow levels to evaluate and simulate flow variations under associated climate variable variations. Results demonstrated not any particular method is suited to represent scenarios leading to extreme flow conditions. For selected flow scenarios, the persistence model performance may be comparable to more complex multivariate approaches, and complex methods did not always improve flow estimation. Overall model performance indicates inclusion of river flows and forcing variables on average improve model extreme event forecasting skills. As a means to further refine the flow estimation, an ensemble forecast method is implemented to provide a likelihood-based indication of expected river flow magnitude and variability. Results indicate seasonal flow variations are well-captured in the ensemble range, therefore the ensemble approach can often prove efficient in estimating extreme river flow conditions. The discriminant prediction approach, a probabilistic measure to forecast streamflow, is also adopted to derive model performance. Results show the efficiency of the method in terms of representing uncertainties in the forecasts

ESSAYS ON THE IMPACT OF REGULATORY CHANGES

In the first essay, we study the information content of Form 4 filings under the stricter disclosure regulations introduced by the Sarbanes-Oxley Act (SOX) of 2002, by examining the abnormal returns around the filing date. Our results show that for both the purchase and sale samples, the information content of the filings has improved significantly between the pre- and post- SOX periods. We also find that progressive regulatory changes and the increased uncertainty in the market in recent years as a result of the credit crunch in 2008 have made insider transactions more informative. Our results also show that the rank of the insider (CEO, CFO, etc.) has the most influence in explaining the abnormal returns. Finally, in cross-sectional tests, we find that the information content of the filings is stronger for firms with more information asymmetry. Overall, we report that the more timely filing requirement introduced by SOX has been beneficial for investors, particularly for firms with higher levels of information asymmetry. In the second essay, we examine the effects of the Sarbanes-Oxley Act (SOX) of 2002 on the short and long-run performance of corporate acquisitions. Using a large sample of tender offers between 1996 and 2009, we find that the proportion of value maximizing acquisitions increased after the passage of SOX. The price run-up and the intensity of insider trading prior to the announcement in the target firms have substantially decreased after the Act. Using industry and matched firm portfolios, we also find that both the operating performance and buy-and-hold abnormal returns over the three and five year post-acquisition period improved significantly after SOX. In the final essay, we examine the effects of Ontario Bill-198 (CSOX-2003), the strictest corporate law in Canada. Despite some drawbacks, we find the Act has added significant value contrary to many practitioners’ beliefs. Using a large sample of Canadian tender offers between 1996 and 2009, we find that both target and acquirer shareholders experience higher abnormal returns closer to announcement dates in the post CSOX period. Using industry adjusted portfolio, we also find that the long term post-acquisition operating performances for the acquiring firms have significantly improved in the post-Act period. Overall, our results suggest that CSOX has an incremental positive impact on Canadian acquisition activity

Gestor documental para una compañía farmacéutica basado en Microsoft SharePoint

Un gestor documental basado en las tecnologías de Microsoft puede resultar útil para la colaboración y compartición de información con los compañeros de trabajo. El objetivo de este proyecto es la creación de un espacio documental para el departamento de compliance de una compañía del sector farmacéutico. Para ello, se desarrollará una plataforma web que permitirá a los responsables de diferentes áreas la publicación y distribución de la documentación oficial de la organización con el fin de notificar a los usuarios implicados su lectura obligatoria. Por tanto, deberá quedar una constancia de la lectura reglamentaria de los documentos por parte de los involucrados ante una auditoría.A document manager based on Microsoft technologies can be useful for collaboration and information sharing with co-workers. The goal of this project is the creation of a documentary space for the compliance department of a company in the pharmaceutical sector. For this, a web platform will be developed that will allow those responsible for different areas to publish and distribute the official documentation of the organization in order to notify the users involved of its compulsory reading. Therefore, there must be a record of the mandatory reading of the documents by those involved before an audit

Future Panorama of Bangladesh Garments Concerning SWOT Scrutiny

Bangladesh faces significant constraints in this regard of global apparel sector and hence it is not possible to establish strong backward linkages overnight. Therefore, to retain competitiveness in the global market, Bangladesh has to think of other alternatives. This enhancement takes time, but it ensures the long-term sustainability of a firm like apparel industry. In contrast, improving only “competitive performance” and not “capability” may not be sufficient to ensure the long-term development of the apparel industry of Bangladesh. This study addresses the competitiveness issue from two broader dimensions: facade stage and unfathomable stage competitiveness. More advanced scenarios resulting from the further development of the domestic textile, garment and infrastructure sectors will contribute to further improvement of both unfathomable and facade stage competitiveness of the Bangladesh RMG industry. Key words: SWOT, Competitiveness, RMG, Sustainability, Industrial Advancement and Scrutiny

UNDERSTANDING COMMUNICATION NETWORK COHESIVENESS DURING ORGANIZATIONAL CRISIS: EFFECTS OF CLIQUE AND TRANSITIVITY

Various terms such as organizational mortality, organizational death, bankruptcy, decline, retrenchment and failure have been used in the literature to characterize different forms and facets of organizational crisis. Communication network studies have typically focused on nodes (individuals or organizations), relationships between those nodes, and subsequent affects of these relationships upon the network as a whole. Email networks in contemporary organizations are fairly representative of the underlying communications networks. We show that changes in communication networks and its associated group cohesiveness have implications for studying organizational crisis. In this paper, we analyze the changing communication network structure at Enron Corporation during the period of its crisis (2000-2001). Our goal was to understand how communication patterns and structure were affected by organizational crisis. Drawing on communication network crisis and group cohesiveness theory, we tested several propositions using the Enron email corpus: (1) Number of cliques increases, and (2) Communication network becomes increasingly transitive as organizations experience crisis. The results of the tests and their implications are discussed in this paper