616 research outputs found
There is so much you can learn from another culture
No full textJenny de Boer was recently awarded the Delft University Fund’s ‘Marina van Damme’ grant for talented female TU Delft alumni. She intends to spend the \u809,000 prize on a Master’s programme in cultural anthropology
Musketry : the Anglo-Boer War experience
Get PDFCITATION: Ellis, J. 2000. Musketry : the Anglo-Boer War experience. Historia, Historia, 45(2).The original publication is available at https://upjournals.up.ac.zaThe conflict between the Zuid-Afrikaanse Republic (ZAR) and Great Britain was not the first experience the British had of Boer tactics and musketry. The British had the opportunity to study the military system and approach to warfare as practised by the Boers for almost a hundred years. Still, they suffered severe losses against a "lesser" enemy who understood better the employment of the new smokeless magazine rifles. In order to understand the imbalance in the effectiveness of British and Boer firepower, the background of both the British and Boer soldiers opposing each other on the battlefields of southern Africa is illustrated. In doing so the author draws a comparison between the British soldier and his Boer opponent.Publisher's versio
Design strategy structural concrete in 3D focusing on uniform force results and sequential analysis
No full textIntroduction (chapter 1) In analysis software models the infrastructural constructions are often reduced to geometrical linear and surface models (plane stress and shell models). The selection of a model much depends on the speed of the analysis process and the total processing time. The increased computer power has boosted the visualisation of pre-designs since the end of the nineties. The multi-disciplinary nature of a (pre-)design has also placed more focus on the Building Information Model (BIM). This concept may be regarded as a continuation of the product models of the eighties. Modelling of structures (chapter 2) Our aim is to (re)use the geometrical data from the visualisation software, presented as solid models, in the design software. We also want other (even non-technical) disciplines to gain an insight into the structural designs. This makes the use of solid models in the analysis software obvious, especially in the case of structural concrete designs that have more volume if compared to steel designs. In steel we express thickness in millimetres, whereas in concrete these quickly become centimetres. As far as overall processing time is concerned, the analysis of solid models (total analysis time including time for input and output) is no longer a problem for the current computers. However, the analysis software generally does not connect with the structural design in concrete, especially when it comes to calculating the amount of reinforcement. After all, solid models present the stresses, strains and deflections as the result of an analysis, whereas the calculation of the amount of reinforcement is based on forces and moments. Transparent results for the differences in analysis models (chapters 3, 4 and 5) In the first part of this PhD research we have developed a procedure to obtain forces and moments from the solid models. The forces and moments are calculated and presented on reference lines or reference planes by integrating stresses along heights or widths of a section. These reference lines and reference planes may be compared to the ‘old’ system lines or system planes of the linear and surface models. This means that there is full transparency(uniformity) in the results regarding the possible analysis models. The same procedure is suitable for geometrical orthotropic models such as structures. In the past the box structures in the analysis process were mostly calculated using orthotropic surface models due to the desired reduction of the overall processing time of the analysis itself. The results of the 3D geometrical surface models and reference planes in this study may be compared to the results based on the ‘old’ orthotropic analysis models. At the result level the analysis models are now transparent. The course of stresses and/or strains has now been made more clear. This especially applies to structural areas that cannot be related directly to pure bending, but which are still disturbed areas. This is therefore an important step towards improved acceptance of solid models in structural design. The speed of the computer and the developments in the field of internal equation solutions in analysis software have produced so much gain in time in recent years that the overall processing time has become minimal. Although the analysis time of a solid model will still remain longer than with other models, the time required to schematise a structure has been reduced. The schematisations are necessary in linear and surface models, while still leading to a number of limitations for the result. The improved clarity and the possible checks on the design mean that the quality of the analysis model has strongly improved. This may lead to a reduction of the overall failure cost in construction, estimated to amount to 7-12% of the total building sum. Sequential analysis (chapter 6) The second part of this PhD research deals with the consistent checking of a (pre-)design. In practice, the checks on the designs of concrete structures are done on the basis of regulations, including safety factors. Earlier, there was only a single general structural safety factor, but this has now been split up into partial safety factors for both the material and the load. In concrete structures the checks mainly take place in various cross sections. When checking the cross section, the designer can start from cracked concrete, but not when determining the course of the forces of the entire structure. This is not consistent. A crack pattern leads to a redistribution of forces, and by allowing a crack pattern to a limited extent and by using partial safety factors, the safety of the entire structure is still guaranteed. The fully non-linear analyses that include the integral crack pattern may then be applied to demonstrate the safety. The regulations indicate how such a check should take place, but this is not an accepted procedure in current engineering practice. It is also not mandatory. A fully non-linear analysis of a structure is time-consuming, and is considered to be a highly specialist analysis. Also, it is not guaranteed in advance that it leads to the saving of costs. Perhaps this non-linear analysis process should be used for the assessment of the integral life cycle cost rather just the building cost. The assessment of safety and risk has become increasingly important in the design of a structure. That is why it is desirable in the analysis to assess the actual stresses in steel and concrete during the serviceability limit state of a structure in connection with the chance that it will occur. The eventual cracked state must be analysed using a non-linear analysis up to the serviceability limit state. This still causes practical problems. Although the crack pattern is still limited in this state, it may interfere to the extent that the non-linear process does not reach this desired load level through the instability of the software. This is often caused by the redistribution of forces or stresses. To obtain a stable analysis process we have developed a calculating method that will supply a robust redistribution of forces and moments. This method also serves to check the ultimate limit state of a structure. This defines the aim of the second part of this PhD research. We have selected a quasi nonlinear method, consisting of a series of linear elastic calculations. We call this a sequential analysis. The solution routine should remain robust throughout the crack pattern, allowing redistribution by the crack pattern. Through iterative reduction of the material properties (stiffness and tensile strength) of concrete within an always robust linear analysis, this method can be used for an entire structure. The total processing time can be estimated after one iteration. Up to the level of the ultimate limit state a maximum of 60 iterations is needed, 4 iterations per load increment. This has reduced the processing time from days to hours. Verification and validation of sequential method (chapters 7, 8 and 9) The sequential method has been tested against three experiments conducted in Toronto, Canada, that were also subjected to a fully non-linear analysis. The results are equal for both the experiments and the fully non-linear analysis. The crack widths can be determined directly from the analyses and be compared to the admissible values. Sensitivity assessments in analyses of the same experiments indicate how the partial safety factors are influenced. Sensitivity analyses (chapter 10) The real results from this analysis form the basis of a safety assessment through partial safety factors or a probabilistic analysis, resulting in the probability of a fault or failure. If the design does not comply with the required level, it can be adjusted. In this manner the design chain has been closed in the sense that a check has taken place on the basis of consistent results in a closed analysis process. The assumption is that through a regulation specific aspects are covered by partial safety factors. This assumption has gained more ground as a result of this research. Also, the integral method offers possibilities for optimisations in the design of concrete structures. This closed analysis process has created the possibility to start an automated design process. The acceptance of the new process is also in line with the present focus on integral design costs based on life cycle, environment and durability. Apart from the design of new structures, the tool developed here is also very suitable for the assessment of the condition of existing structures. Important in this respect are changes in the material properties or in the load. On the basis of the archived geometry and the reinforcement that is present we can now quickly assess the influence on the safety factors.Design & ConstructionCivil Engineering and Geoscience
COL F.F. PIENAAR'S BOER WAR DIARY (PART I)
Get PDFIn 1902, Filip Pienaar, a young Boer officer in exile at the Monastery of Tomar in Portugal, recorded his Boer war experiences. These were published by Methuen in 1902, under the title With Steyn and De Wet, The book was banned one month after publication, The author, Lt Col F.F. Pienaar, later joined the Union Defence Force, served in the German South West Africa Campaign and later became South Africa's first ambassador to Portugal in 1939, from where he also conducted correspondence with his cousin General Dan Pienaar. As a son-in-law of the late F.F. Pienaar, it is my privilege to reproduce part of his Boer War experiences. Pienaar's account is one of the first books on the Boer War and covers several eye-witness accounts at that time.</p
Gone with the shining things
No full textIncludes bibliographical references.The lure of gold in the great reefs of Johannesburg near the end of the 19th century not only attracted the famous mining barons such as Cecil John Rhodes, Alfred Beit and Barney Barnato: working men also came from far and wide to feed their families with their labour. Among them was my great-grandfather, the miner from the Isle of Man, William Cogeen. He arrived via the tin mines of Cornwall and the silver mines of Colorado, and was among those Uitlanders who flocked in those early days to the Transvaal as skilled artisans - wheelwrights, farriers, bricklayers and, especially, experienced hard-rock miners. It was their labour, as well as of black tribesmen from all over southern Africa, that laid the financial foundation for what became the rich city of Johannesburg. It was also their influx that was the excuse that precipitated the Anglo-Boer War. His wife and daughters joined him in what was still a rough boom town, and they stayed on, until forced to flee as refugees from Johannesburg at the start of the war in 1899. Intrigued by the stories my mother and grandmother told me as a child, I began to research my family’s history and travelled to the Isle of Man, Cornwall and Colorado to trace their origins - and my own. This is the remarkable story of what happened to an ordinary working-class family who lived in extraordinary times, and my journey in their footsteps
The analysis of lipophilic marine toxins : development of an alternative method
No full textLipophilic marine toxins are produced by certain algae species and can accumulate in filter feeding shellfish such as mussels, scallops and oysters. Consumption of contaminated shellfish can lead to severe intoxications such as diarrhea, abdominal cramps and vomiting. Methods described in European Union (EU) legislation to test for the presence of these toxins are based on a mouse or rat bioassay. These assays are unethical and have a poor sensitivity and selectivity. The aim of this thesis is to develop an alternative method based on liquid chromatography - tandem mass spectrometry (LC-MS/MS) for the quantitative analysis of lipophilic marine toxins. LC-MS/MS methods described in literature for the determination of lipophilic marine toxins used an acidic chromatographic system. Under acidic conditions peak shape and separation of a number of toxins preferably analyzed in electrospray ionization negative (ESI–) and positive (ESI+) were poor. A LC-MS/MS method with alkaline chromatographic conditions in which we were able to analyze 28 different toxins in a single analysis in separated retention time windows operating in either ESI– or ESI+ was developed. Furthermore, a clean up procedure based on solid phase extraction (SPE) was developed to reduce the amount of matrix effects (ion suppression and enhancement). A combination of SPE clean up and alkaline chromatographic conditions resulted in reduced matrix effects for all matrices tested (mussel, scallop and oyster). The developed SPE & LC-MS/MS method was in-house validated at regulatory limits based on EU Commission Decision 2002/657/EC. With respect to accuracy, repeatability, reproducibility, decision limit, specificity and ruggedness the method performed well. The method also performed excellently in view of possible new limits that are four- to five-fold lower than current limits for some toxins. Finally a screening method based on LC orbitrap MS was developed for 85 marine toxins of which most are not stated in EU legislation. The screening used in-house developed software which made it possible to reduce the complex data files and screen for a large number of toxins within seconds. This thesis will contribute to the replacement of the animal assays that are still prescribed in EU legislation for the determination of lipophilic marine toxins in shellfish. </p
Transport van granulair bodemmateriaal: Een onderzoek naar transport bij lage hydraulische belasting
No full textVloeistofmechanica van de TU Delft. De experimenten zijn uitgevoerd onder gelijke condities als bij de onderzoeken van Paintal (1969) en De Boer (1998). Bij de onderzoeken is dezelfde bodemopbouw, hetzelfde bodemmateriaal en dezelfde aanleg van het testbed gebruikt. De meettechnieken waren bij de onderzoeken verschillend, maar hadden als uitgangspunt dezelfde definitie van transport: het volume bodemmateriaal dat door een raai verplaatst per eenheid van breedte en per tijdseenheid. De experimenten die in dit onderzoek zijn uitgevoerd leveren informatie op over de oorzaken van de verschillen tussen de resultaten van onderzoeken van Paintal (1969) en De Boer (1998). De resultaten van de experimenten van dit onderzoek leiden tot de volgende coclusies over de invloedsfactoren: - De vorm van het bodemmateriaal heeft geen invloed op het transport bij de hydraulische belastingen en het bodemmateriaal die in dit onderzoek zijn toegepast. - Gedurende een meting verandert de hoeveelheid transport in de tijd, er treedt een rijpingsproces op. Het bed stelt zich in op de belasting waardoor geleidelijk het transport daalt tot een constante waarde. Bij de experimenten van dit onderzoek was in 90% van de gevallen het transport tijdens het rijpingsproces één tot zes keer hoger dan na het rijpingsproces. De resultaten van de verschillende onderzoeken zijn vervolgens vergeleken. Dit heeft geleid tot de volgende conclusies: - De mobiliteitsparameter is in het onderzoek van Paintal (1969) en het onderzoek van De Boer (1998) verschillend gedefinieerd. De hydraulische belasting op het bodemmateriaal is in de mobiliteitsparameter verwerkt met de bodemschuifspanning ( b). De schuifspanning die door de stroming op de bodem wordt uitgeoefend is afhankelijk van de ruwheid van de bodem. Deze ruwheid kan vervolgens worden gesplitst in de ruwheid van het bodemmateriaal en de ruwheid van de vorm van het bed. Bij het onderzoek van Paintal is alleen de schuifspanning in de mobiliteitsparameter verwerkt die afhankelijk is van de ruwheid van het bodemmateriaal. Bij het onderzoek van De Boer is de schuifspanning in de mobiliteitsparameter verwerkt van de bodem. Het verschil in transport kan worden verminderd door dezelfde schuifspanning te verwerken in de mobiliteitsparameter. - De transportparameter is in het onderzoek van Paintal (1969) en het onderzoek van De Boer (1998) gelijk gedefinieerd: het volume bodemmateriaal dat door een raai verplaatst per eenheid van breedte en eenheid van tijd. Bij het onderzoek van De Boer wordt echter het transport onderschat door het transport te meten over bijna de gehele breedte van de goot. De experimenten zijn bij het onderzoek van De Boer uitgevoerd in een smalle kantelgoot (B/h=2). De invloed van de wanden op de stroming is niet te verwaarlozen; de snelheid van de stroming is bij de wanden lager dan in de as van de goot. Het transport van bodemmateriaal is sterk afhankelijk van de snelheid van de stroming. De mobiliteitsparameter wordt in het onderzoek gerelateerd aan het snelheidsprofiel in de as van de goot; hierdoor wordt minder transport gemeten dan representatief is bij de mobiliteitsparameter. Dit leidt tot de volgende hoofdconclusie: De verschillen tussen de resultaten van de onderzoeken van Paintal (1969) en De Boer (1998) zijn te verklaren met de verschillen in meettechnieken en definities. De resultaten van het onderzoek van De Boer onderschatten het transport en kunnen hierdoor niet worden gebruikt om het transport van bodemmateriaal te voorspellen. Met de resultaten van de onderzoeken van Paintal en Forschelen (1999) kan het transport van bodemmateriaal wel worden voorspeld. De resultaten van de onderzoeken van Paintal en van Forschelen verschillen afhankelijk van de gebruikte definitie van de mobiliteitsparameter. Bij een mobiliteitsparameter gerelateerd aan de bodemschuifspanning komen de resultaten van de onderzoeken van Paintal en van Forschelen overeen. Bij een mobiliteitsparameter gerelateerd aan de korrelschuifspanning (schuifspanning gerelateerd aan de ruwheid van de korrels) komen de resultaten niet overeen; het transport van volume bodemmateriaal is factor twee tot vijf lager bij metingen van het onderzoek van Paintal ten opzichte van de metingen van het onderzoek van Forschelen.Hydraulic EngineeringCivil Engineering and Geoscience
Erratum: An algorithm-based topographical biomaterials library to instruct cell fate (Proceedings of the National Academy of Sciences of the United States of America (2011) 108, 40 (16565-16570) DOI: 10.1073/pnas.1109861108)
Get PDFAPPLIED BIOLOGICAL SCIENCES Correction for “An algorithm-based topographical biomaterials library to instruct cell fate,” by Hemant V. Unadkat, Marc Hulsman, Kamiel Cornelissen, Bernke J. Papenburg, Roman K. Truckenmüller, Gerhard F. Post, Marc Uetz, Marcel J. T. Reinders, Dimitrios Stamatialis, Clemens A. van Blitterswijk, and Jan de Boer, which appeared in issue 40, October 4, 2011, of Proc Natl Acad Sci USA (108:16565–16570; first published September 26, 2011; 10.1073/pnas.1109861108). The authors note that Anne E. Carpenter and Matthias Wessling should be added to the author list between Roman K. Truckenmüller and Gerhard F. Post. Anne E. Carpenter should be credited with analyzing data. Matthias Wessling should be credited with designing research. The corrected author and affiliation lines, and author contributions appear below. The online version has been corrected
Model-Based Testing of Environmental Conformance of Components
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