3,766 research outputs found
Differences between a 3 dimensional probabilistic method of berthing structure design and the traditional method of a berthing structure design
No full textJetties are designed by the guidance of the deterministic standards. These standards are based on the standardized values of safety factors (semi-probabilistic) and use the load and the capacity of every element as a standard value. The interaction of every separate element as a part of a whole is not taken in to account. The use of deterministic standards can result in a design that is not economically optimal. A probabilistic approach gives a better insight in the occurrence of an unwanted events and leads to more insight of the optimizing of the structure. The “Lyondell jetty” in the Europort in Rotterdam is used as reference structure. This jetty is constructed in 1997 and is in use by a manufacturer of chemical derivatives for all kinds of synthetic products. It concerns a continues berthing structure founded on piles and is covered with fender wood, with a double deck jetty, that offers space to berth two large sea vessel and two smaller barges. The failure of the berthing structure is a conditional chance for functioning of the jetty. The berthing structure is submitted to further examination by means of a Monte Carlo simulation. Using the Monte Carlo simulation a measure of failure of an event is expressed in strength and resistance. In this study this event consists of reaching the yielding stress in the structure or the exceeding of a determined boundary of deformation during the berthing of a vessel. The energy loading is introduced with the equation of Saurin. The soil is modelled as a spring and meets the requirements of the Winkler model. In analysing the deformations of the structure the soil needs to have elasto-plastic characteristics (p-y curves that were developed by Reese). The actual structure that was designed with the Blum method, the design was recalculated, using help of p-y curves. This becomes the Kool model that is used for comparison with the results of the Monte Carlo simulation. In this thesis only the berthing of the mooring point 2 (large sea vessel) is considered. First the question if the developed 3 dimensional simulation technique is applicable answered and second whether the application of the model leads to differences in capacity. The soil model developed in Scia-engineer has the same behavior as in M-pile and the structure shows the expected behavior according the rules of mechanics. In the model relating to the energy load the variables of length, width, depth, mass, angle of berthing and the coordinates of impact are described as a stochastic. In the resistance of the structure the volume weight, internal angle of friction, cohesion, yielding stress and wall thickness of the tubular segments are described as a stochastic. From the results it appears that the loads occurs only very locally. Consequently there appears an over capacity in the reference design relating to the length of all the piles and the diameter of the piles. The five most loaded piles in the structure are checked due to the energy loading of the bow at Mooring Point 2. It appeared that the diameter of these piles can have a smaller fitted diameter. In length a reduction of 9% is found. A trend can be distinguished that indicates a large reduction of capacity in length over the whole structure. The critical variable in the design is the velocity of the vessel. The critical element in the structure is the berthing beam self. The sensitivity analysis of strength indicates that the chance of failure in strength can be diminished by the strengthening of the berthing beam and reducing the thickest wall thickness’s of the piles.Hydraulic EngineeringHydraulic EngineeringCivil Engineering and Geoscience
On-load Tap Changer Diagnosis on High-Voltage Power Transformers using Dynamic Resistance Measurements
No full textHigh-voltage transformers have tap changers to regulate the voltage in the high-voltage network when the load changes. Those tap changers are subject to different degradation mechanisms and need regular maintenance. Various defects, like contact degradation, often remain undetected and the probability of maintenance errors cannot be neglected. Preventive diagnosis of dynamic resistance can be used to determine the contact condition and to check the basic function of the tap changer. This can guarantee that the high-voltage transformer can be put back into operation safely after maintenance. In addition, the information obtained can be used for condition-based maintenance. The research of Jur Erbrink elaborates on the condition assessment of tap changers using dynamic resistance measurements. He describes in his thesis the different ways in which the measurements can be performed and how this influences the measurement results. In particular it was emphasized that the dynamic resistance measurements at a lower the test current are more sensitive for long term aging effects. It is also investigated which defects can be detected and how the results can be interpreted.High Voltage Technology and ManagementElectrical Engineering, Mathematics and Computer Scienc
Forensic Analysis of Levee Failures: The Breitenhagen Case
Get PDFForensic analysis of past failures is valuable to improve our understanding of levee behavior. In this article a new systematic approach of forensic analysis for levee failures is proposed and applied to the Breitenhagen levee breach that occurred along the river Saale in Germany in 2013. The purpose of this study is to identify the cause of the breach based on the proposed approach, even though limited data is available. Based on the information prior, during and after the breach of the levee, a slope stability model is developed for the entire event. First, results from this model are obtained based on the expected values of the uncertain parameters and the best estimates of the situation. Uncertainty of the model is included in the calculation subsequently by defining possible failure scenarios. The most likely failure scenarios are derived from the data and included into the model so that it is possible to eliminate or validate all possible causes by means of a sensitivity calculation. It is concluded that the levee breach is likely caused by locally weak soil conditions, unexpected high water pressures due to a connection between a pond and the aquifer and unexpected saturation of the levee. These conditions are associated with the occurrence of a previous breach at this location.Hydraulic Structures and Flood RiskGeo-engineerin
Public Programs at The New York Public Library.
No full textAmong the varied programs offered by the Library during the Spring, a series of lectures, Fables: From Aesop to La Fontaine, gets a page of recognition. The series is done by Marcel M. Gutwirth. It is meant to support and coincide with the Library's La Fontaine: The Power of Fables exhibition, co-curated by Paul LeClerc. The booklet features eight outstandingly-reproduced engravings by J.J. Grandville, including the cover engraving of the two high-society goats unable to pass through the doorway at the same time.Paul LeClerc
Kamloops, the hub
Get PDFPublished by the Kamloops Secondary Resource Centre with the co-operation of the Kamloops Secondary School Art and Commerce Department. Contains historic essays with the following chapter titles: Stkamlu-leps-mux - The People of the Confluence; Cumcloops; Fur Trading Days; The Old Saint - A Biography of Mr. Captian Saint Paul, Chief of the Shuswap Indians; Education comes to Kamloops; Principals of the Kamloops Schools 1886-1959. J.J. Morse was a former teacher.Not peer reviewedHistoric bookletCumcloop
Hindcasting of levee failures: Deterministic and probabilistic methods
No full textIn the last century, approximately 100,000 people lost their lives during a flood event and over 1.4 billion people were affected. As the population and economic activities grow in flood-prone areas and the frequencies and intensities of flood events increase due to climate change, damage due to flooding is expected to increase. To limit and control the potentially increased risks, in many locations flood defences, such as levees, are built and existing flood defences are reinforced. It is thus important to be able to properly estimate the reliability of these levees and to understand their potential failure mechanisms. In particular, there are significant uncertainties associated with the occurrence of geotechnical failure mechanisms such as slope instability and piping.The hindcasting of levee failures can provide valuable information about the factors and uncertainties that dominate levee performance and reliability. Systematic forensic engineering approaches to evaluate failed structures and methods of hindcasting have been developed in the field of structural engineering, but these are not well applicable to failed levees. This is mostly due to the scarcity of relevant information prior to, during or after the levee failure, which leaves multiple scenarios and alternative model choices possible to characterize the event.This thesis proposes and demonstrates methods for systematic analysis of levee failures at the individual section and system level. These methods of hindcasting are expected to contribute to the overall quality, repeatability, transferability, transparency and recognisability of the analysis of levee failures. In this thesis, existing approaches for evaluating structural failures have been adapted to analyse levee failures using both deterministic and probabilistic techniques. This thesis focuses on the levee failure mechanism of slope instability of the inner slope.Firstly a deterministic method is proposed which is applied to a slope failure. In this method, the uncertainties in possible causes and computational models are modelled by defining possible scenarios explaining the failure based on all the information available. The influence of the identified scenarios and possible alternatives in model choices are analysed through a sensitivity analysis. Results of the computations are confirmed or refuted by observation information of the failure such as the shape of the failure surface. To illustrate the method, it is applied to the levee failure near Breitenhagen (2013), in Germany in Chapter 2 of this dissertation. The levee near Breitenhagen is located at the intersection of the Saale and the Elbe and it failed due to instability of the slope at the polder side of the levee. Unexpected saturation of the levee, steep slope of the levee, and the influence of the tree roots were identified to cause of the levee failure by previous reports. However, in the present study, an old breach was found to be there (the first proxy was a pond likely caused by this old breach next to the levee; the old breach was later confirmed with archive research). This old breach and pond resulted in a scenario with low strength and high water pressures in both levee and the aquifer and was identified to be the most likely scenario explaining the failure. The results indicate that locally low values of shear strength (low values of pre-overburden pressure or cohesion) explain the failure. Other scenarios that were evaluated resulted in a situation that was not likely to fail or, resulted in a slip surface that differs from the observed failure surface.The deterministic method does not quantify uncertainties explicitly. That makes it difficult to uniquely identify the most likely scenario to explain the failure. Therefore the deterministic method is advanced by making it probabilistic and by including Bayesian techniques in Chapter 3. Thereby a better insight is provided into the relative likelihoods of the various scenarios explaining the failure. Failure observations (water level at failure, the shape of the slip surface, etc.) and a-priori levee information (soil layering, shear strength etc) are systematically taken into account to quantitatively identify the most likely scenario explaining the failure and the most representative model choices to most accurately characterise the failure. The Bayesian techniques are also used for updating the scenario and possible alternatives in model choices using the observations of the actual failure (if present) such as the shape of the slip surface. To illustrate the method, it is also applied to the levee failure near Breitenhagen (2013) in Germany. Similar to the deterministic method, the old breach resulting in a scenario with locally weak soil and aquifer connection is found to be the most likely scenario. Further, the Limit equilibrium using Spencer’s approach and undrained soil response is identified to be the most representative model choices. The shear strength ratio is identified as the 6 most dominant contributor to the failure. Compared to the “deterministic method” introduced in chapter 2, the probabilistic method adds the possibility to quantitatively substantiate the identification of the most likely scenario explaining the failure as well as the most representative model choices.Both methods of hindcasting have had little application and validation. Therefore both methods have been applied to a large-scale levee failure experiment. The levee of the Leendert de Boerpolder, in the Netherlands, was brought to failure under controlled circumstances. As a result, very detailed information is available. The levee was brought to failure by gradually lowering the water level in an excavated ditch at the polder side of the levee. Since the water level drawdown is known at the time of failure, this information is used to validate the outcome of both methods of hindcasting. The available levee information was used in two steps. In the first instance, only basic information was used in the hindcasting. In the second step, the geometry of the observed slip surface is also included. The probabilistic method using Bayesian techniques required some adjustment, to account for the survival of previous load phases during a stepwise increase of the load. Both methods of hindcasting identified the same water level drawdown at the moment of failure, but different model choices. In addition, the identified water level drawdown is confirmed by the observed water level drawdown at the time of the failure, i.e. 1.6 m.Finally, this thesis introduces a method to quantify the influence of deviating conditions on the failure rate of a levee by looking at failures on a system level. The annual failure rate of a levee section is assessed based on information from historical floods. The return period of past events is also taken into account. The presence of deviating conditions at failed and survived levee sections is analysed based on satellite observations. Bayesian techniques and likelihood ratios are used to update the average failure rate as a function of the presence of a deviation. The river system of Sachsen-Anhalt, Germany, is used as a case study. It experienced severe floods with many levee failures in the years 2002 and 2013 resulting in the failure of 41 levee sections due to internal erosion, instability or overflow. It is found that the presence of geological deviations has a significant influence on the observed failure rate and that the failure rate increases with the magnitude of the hydraulic loading. The results show that in the case of the occurrence of a visually identifiable geological deviation in the subsurface, the updated failure rate of a section is about 14 times high than when there is no visually identifiable deviation. The presence of other deviations, such as bushes or trees, or permanent water near the levee also results in a somewhat higher failure rate (20–30% higher) than the calculated average annual failure rate. It is also discussed how the expected number of failures in a system during a high water event with a certain magnitude can be estimated. The results of this research can be used to further optimize soil investigations, calibrate the results of more advanced reliability analyses, and complement risk assessments. The method offers opportunities in particular in environments where little data is available.Overall, the methods and insights developed in this thesis can contribute to a better understanding of the performance and reliability of flood defence systems.Hydraulic Structures and Flood Ris
PHB metabolism and N-removal in sequencing batch granular sludge reactors
No full textApplied Science
Kamloops, the hub
No full textPublished by the Kamloops Secondary Resource Centre with the co-operation of the Kamloops Secondary School Art and Commerce Department. Contains historic essays with the following chapter titles: Stkamlu-leps-mux - The People of the Confluence; Cumcloops; Fur Trading Days; The Old Saint - A Biography of Mr. Captian Saint Paul, Chief of the Shuswap Indians; Education comes to Kamloops; Principals of the Kamloops Schools 1886-1959. J.J. Morse was a former teacher.Not peer reviewedHistoric bookletCumcloop
Eddies and currents: A review of Upstream, anyone? A critical reply to J.J. Fellows’ Downstream of the experts, by Raphael Sassower
No full textJill Fellows responds to Raphael Sassower's review 'Upstream, anyone? A critical reply to J.J. Fellows’ Downstream of the Experts.'Final article published
WILLIAM KENRICK, "PREFACE TO ELOISA BY J.J. ROUSSEAU" (1761)
No full textELOISA : BY J.J. ROUSSEAU, PREFACE By the Translator [William Kenrick], 4 vols. London : Griffiths, Becket and De Hondt, 1761. Read the French translation Download the bilingual version of the text (pdf) William Kenrick (1729/30-1779) was a typical eighteenth-century hackwriter. He is the author of verse satires and plays (some of which were successful), he was a contributor to and editor of several periodicals, he gave public lectures on Shakespeare, he is the author of a dictionary of the E..
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