Is 1 + 1 = 2 ? Results of 3D model experiments on piled embankments

Most design models for basal reinforced piled embankments design the geosynthetic reinforcement (GR) as a single biaxial layer. In practice, however, the required strength and stiffness is frequently divided into two ore more GR layers with or without a layer of granular material in between. This paper compares three geogrid-systems : (1) one GR layer consisting of one biaxial geogrid and a (2) one GR layer consisting of two uniaxial geogrids installed directly upon each other and (3) two geogrids with a fill layer in between. Five model tests have been carried out to study the differences between these three systems. This test series has been presented earlier by Van Eekelen et al. 2012a. The present paper presents part of the results. It was shown that the behaviour of the first two systems is the same: the GR stiffness of the biaxial geogrid is apparently the same as the summed stiffness in each direction of the two uniaxial grids. It was also shown that the application of a fill layer between the two GR layers results in a slightly more linear dependency of the net load on the fill aan in the end of the tests, in slightly more arching. However, the differences are very small. The GR stiffness, for example, has much more influence than whether or not a fill layer has been applied between the two GR layers. It is therefore concluded that the stiffness and strength of two or more GR layers can be summed, thus 1 + 1 = 2 indeed

Scenarios for the Dutch gas distribution infrastructure in 2050

In the Netherlands 98 percent of the households are connected to the gas grid. Th is grid, aging, will need investments. What are its system requirements in the future? No consensus exists on that question. Th erefore, it is diffi cult to determine what to invest in. To help solve this problem, we have developed four scenarios for the Dutch gas distribution infrastructure in 2050. A structured scenario development process was used taking a number of existing scenarios as a starting point. Th e key forces that form the basis of our scenarios are the willingness and ability to reduce green-house gases and the perceived resource scarcity. Next to these, we have included forces that shape the scenarios, namely projected energy demand, available sources of supply, technological developments and institutional developments. Th e energy demand and the available sources of energy were quantifi ed for each scenario. We have determined what the impact will be on the geographical scope of the grid, the type and mix of gases that are transported, and the function of the distribution grid in the larger energy system. We argue that these scenarios may help in dealing with the investment dilemma. Th ey can be used to detail the possible functions of the gas distribution system in the Netherlands in 2050

Distributionally robust views on queues and related stochastic models

This dissertation explores distribution-free methods for stochastic models. Traditional approaches operate on the premise of complete knowledge about the probability distributions of the underlying random variables that govern these models. In contrast, this work adopts a distribution-free perspective, assuming only partial knowledge of these distributions, often limited to generalized moment information. Distributionally robust analysis seeks to determine the worst-case model performance. It involves optimization over a set of probability distributions that comply with this partial information, a task tantamount to solving a semiinfinite linear program. To address such an optimization problem, a solution approach based on the concept of weak duality is used. Through the proposed weak-duality argument, distribution-free bounds are derived for a wide range of stochastic models. Further, these bounds are applied to various distributionally robust stochastic programs and used to analyze extremal queueing models—central themes in applied probability and mathematical optimization

Trading in Target Stocks Before Takeover Announcements: An Analysis of Stock and Option Markets

In this study we examine both informed trading and contraire trading preceding takeover announcements on US target firms. Our findings suggest that both informed trading and contraire trading exists within the period preceding takeover announcements on both the stock and option markets as evident through abnormal returns and trading volumes. In regard to contraire trading, this study investigates possible explanations for its existence including liquidity clustering, falsely informed trading and deliberate contraire trading. The results find that bid-ask spreads actually increase over the pre-announcement period indicating that liquidity clustering is an unlikely explanation. However, through analysis of an unbiased sample of rumoured target firms, deliberate contraire trading appears both a profitable and more likely explanation for contraire trading than falsely informed trading.Informed Trading; Contraire Trading; Market Efficiency; Event Study

Information Leakage and Informed Trading Around Unscheduled Earnings Annoucnements

While there has been much judicial discussion regarding the competency of Australia’s continuous disclosure regime with reference to contemporaneous international standards, there has to date been limited empirical analysis of the Australian system’s effectiveness in preventing selective disclosure and information leakage. This paper presents an empirical study of information content and trading behaviour around unscheduled earnings announcements – comprising of profit upgrades, profit warnings and neutral trading statements – made by ASX-listed companies during 2004. The contention is that informed trading impacts on the stock returns and trading volumes of listed entities, and hence abnormal returns or trading volumes observed prior to an announcement provide evidence of information leakage. The paper models a range of factors that potentially influence firm disclosure practices and contribute to the level information asymmetry in the market during the pre-announcement period. Previous research has investigated the influence of firm size and information content in contributing to information leakage. This study further considers the variables of firm growth, capital structure and industry group.INFORMATION LEAKAGE, UNSCHEDULED ANNOUNCEMENTS, DOWNGRADES

Distributionally robust views on queues and related stochastic models

This dissertation explores distribution-free methods for stochastic models. Traditional approaches operate on the premise of complete knowledge about the probability distributions of the underlying random variables that govern these models. In contrast, this work adopts a distribution-free perspective, assuming only partial knowledge of these distributions, often limited to generalized moment information. Distributionally robust analysis seeks to determine the worst-case model performance. It involves optimization over a set of probability distributions that comply with this partial information, a task tantamount to solving a semiinfinite linear program. To address such an optimization problem, a solution approach based on the concept of weak duality is used. Through the proposed weak-duality argument, distribution-free bounds are derived for a wide range of stochastic models. Further, these bounds are applied to various distributionally robust stochastic programs and used to analyze extremal queueing models—central themes in applied probability and mathematical optimization