1,040 research outputs found
Damage development in the adhesive zone and mortar of porous asphalt concrete
No full textThis research is focused on damage development in the adhesive zone and the mortar of porous asphalt concrete. The motive of this research is the loss of stone from the pavement surface, the so-called ravelling of noise reducing surface wearing courses. Ravelling is the dominant defect of porous asphalt resulting in huge costs of maintenance and resurfacing in the Netherlands. Ravelling is a mixture-associated problem and is directly related to the binding failure within the stone-to-stone contact regions. This research is thus towards a better understanding of the processes responsible for ravelling, i.e. cohesive failure in the mortar bridge and adhesive failure at the mortar/aggregate adhesive zone on the basis of meso-mechanics. An intensive experimental program was carried out on various adhesive zones and mortars at a meso-sale of millimetres. This program was designed based on a better understanding of stress/strain states in porous asphalt concrete under moving traffic loadings. The aim was to develop fatigue/damage models for the adhesive zone and mortar which allows life expectancy to be predicted. Tension and shear tests as well as tests in which tension and shear were combined were performed on the adhesive zones. Among these tests, uniaxial tension testing was conducted using Dynamic Mechanics Analyzer. Shear testing was performed using Dynamic Shear Rheometer. A test which combined tension and shear was specially designed. Various types of load signals were applied accounting for complex stress signals to which the adhesive zones are subjected in practice. A damage model based on a linear cumulative damage rule was used to explain the obtained test data. The proposed model is making use of the integration of an equivalent uniaxial tensile stress signal to compute the development of damage. To do this, an internal-friction theory was applied to translate any combination of shear and normal stresses into a simple equivalent uniaxial tensile stress. Model fit indicated that the predicted number of cycles to failure is in agreement with the measured data. A practical mortar fatigue model based on the dissipated energy concept was developed for the life predictions under complex multiaxial loadings. The fatigue model is based on the initial dissipated energy per cycle. Model parameters can be determined on the basis of commonly used fatigue tests. The proposed model gave very good results in explaining the laboratory fatigue data. By combining the mortar stress and strain signals provided by response calculations the dissipated energy per tyre passage can be calculated and the number of load repetitions to failure can be estimated using the mortar fatigue model. The developed fatigue/damage models were applied to explain the ravelling damage of four different porous asphalt mixtures used in a full-scale accelerated pavement testing (APT) experiment. Finite element simulations of the behaviour of these four mixtures were made. A 2D idealized model was used for practical reasons. The life expectancy predicted by this way was in good agreement with the results of full scale ravelling tests. The life time predictions as made explain the initiation of ravelling. In reality however maintenance will only be applied if ravelling has extended over a certain area and at a certain level of severity. To relate the computed life expectancy with the actual lifespan of porous asphalt or the maintenance moment, a ravelling development model was proposed. By combining this model with the initial ravelling damage obtained from the simulations, the moment for maintenance and resurfacing can be estimated for planning pavement preservation strategies. Finally, it was concluded that the meso-scale fatigue characterization of the adhesive zone and mortar is feasible. The developed adhesive zone damage model and mortar fatigue model together with the finite element model for the prediction of stress, strain and dissipated energy allow to arrive at a proper ranking in performance of porous asphalt mixtures. It has been shown that the developed models are very useful tools to design porous asphalt concrete with a better raveling resistance and a longer lifetime.Road and Railway EngineeringCivil Engineering and Geoscience
LOT, a meso scale mechanistic tool for Porous Asphalt mixture design; winter damage and LOT validation
No full textBy assignment of the Centre for Transport and Navigation (DVS) of the Dutch Ministry of Transport, Public Works and Water Management the Delft University of Technology developed LOT. LOT is a Lifetime Optimisation Tool for Porous Asphalt, PA, based on meso scale structural modelling. LOT sees an asphalt mixture as a structure and computes stress and strain throughout that structure as a function of mixture component behaviour, mixture geometry, and mixture loading. This paper discusses the validation of LOT on the basis of full scale ravelling test. Further validation is achieved by analysis of winter damage which developed in PA during the Dutch 2008/2009 winter. For this analysis LOT simulations considering Long Term Aged (LTA) PA at temperatures of -10° to +20°C were made. The paper comes to the conclusion that meso scale mechanical models allow ravelling performance based mechanistic design of high performance PA mixtures.Geoscience & EngineeringCivil Engineering and Geoscience
Tiragatso ya itlhagiso ya aetlhare se se okeditsweng ka kgetsi mo bothateng jwa popo ya metato ya dipeipi tsa oli
No full textGo na le mathata a mantsi a ditshwetso tsa tiriso tse di welang mo mathateng a a mo setlhopheng sa kelelo ya kgokagano le palo e kgolo ya dikai tsa tiragatso tse di ka bonwang mo dikgaolong jaaka tsa neeletsanyokgakala, thwalo, boenjineri, saense ya dikhomphutara jalo le jalo. Mo pampiring e, kgonagalo ya go tlhagisa mmotlele wa kelelo ya kgokagano o o leng mmotlele wa kgokagano ya setlhare mme morago re e rarabolole ka go dirisa itlhagiso ya setlhare se se okeditsweng ka kgetsi ka go e batlisisa. Go bapisa le go tlhwatlhwafatsa thekeniki e e tlhagisiwang, thuto ya nnete e e totobetseng e e dirilweng (bothata jwa popo ya motato wa dipeipi tsa oli) e tlhophilwe go tswa mo dikwalong gore e dirisiwe go nna motheo wa porojeke e ya patlisiso. Ka go latela pono ya bothata jwa popo ya metato ya dipeipi, tlhabololo ya sekao sa setlhare se se okeditsweng ka kgetsi se tlaa tlhagisiwa. Tiragatso ya mokgwa o mo bothateng jwa popo ya metato ya dipeipi tsa oli e tlaa tlhagisiwa morago. Maduo a a bonwang a tlaa tlhagisiwa mme a bontsha gore go na le boleng jwa go ka dirisa itlhagiso ya setlhare se se okeditsweng ka kgetsi go ka rarabolola tse dingwe tsa mathata a kelelo ya dikgokagano.There are many practical decision problems that fall in the category of network flow problems and numerous examples of applications can be found in areas such as telecommunication, logistics, engineering and computer science. In this paper, the feasibility of representing a network flow model as a tree network model and subsequently solving it using an extended tree knapsack approach is investigated. To compare and validate the proposed technique, a specific case study (an oil pipeline design problem) was chosen from the literature that can be used as a basis for the paper. Following on an overview of the pipeline design problem, the extended tree knapsack model is developed. The application of this approach to the oil pipeline design problem is then presented. Results indicate that it is feasible to apply an extended tree knapsack approach to solve certain network flow problems
Parsons' Structural-Functional Theory of Law-A Socio-Legal Analysis and Critical Evaluation
No full text本論文首述社會學與人類學中的功能理論，介紹墨頓顯性的與隱性的功能說，再簡介帕森思的生平、著作與學說主旨。接著描寫帕氏社會體系論中四大主要功能：適應、目標達致、整合與類型保持。法律作為社會總體系的次級體系，其主要的功能重在社會控制與社會整合。是故本文的重點在討論作為社會操控機制的法律之特徵，以及法律怎樣運用制裁、管轄、正當性與解釋的手段，配合法律的專業化來達到穩定社會總體系之目的。稍後，本文討論帕氏對契約、雇傭與財產權的剖析。最後，覆述帕氏法律社會學的大旨，評估其得失，以及後人在結構功能論以及體系論方面之發揮，以補充帕氏未竟與未逮之理論大業。This essay deals firstly with the evolution of functionalism in sociology and anthropology. It then treats Merton's distinction between the manifest and latent functions. Subsequently, the focus of the article is on Parsons' theory of social system. Having discussed his career, major writings and essential theoretical contributions, the author dwells on Parsons' four functional imperatives and their relevance to the law as one of the social subsystems. According to him, the law as a mechanism of social control operates in a free and open society in terms of sanction, jurisdiction, legitimation and interpretation with the aid of the legal profession. In addition, Parsons' discussion of contract, employment and property right is highly enlightening and deserves a brief mention. Finally, the treatise critically evaluates Parsons' socio-legal model and supplements it with theoretical modifications and expansions by recent scholars, such as H. Bredemeier, N. Luhmann, G. Teubner and A. Podgorecki
Carbonization and Regeneration of Mo/ZSM-5 Catalysts for Methane Dehydroaromatization
No full text<p>The character of carbonaceous deposits formed during methane dehydroaromatization reaction in the presence of Mo/ZSM-5 catalysts was studied by differential thermal analysis. The dependence of the concentration and condensation degree (C/H ratio) of the carbonaceous deposits on the catalyst synthesis conditions (Mo content = 1-10%, Si/Al ratio in the initial H-ZSM-5 = 17-45) and reaction conditions (feed flow rate = 405-1620 h<sup>-1</sup>, methane concentration = 90-98%, reaction temperature = 720-780 °C) was investigated. The oxidative treatment conditions of carbonized Mo/ZSM-5 catalysts providing stable operation of the catalysts under multiple reaction-oxidative treatment cycles were selected.</p></jats:p
Kua Hiri Mai Te Rā - A journey of self identification for the descendants of Ngāti Rāhiri ki Taranaki
No full textPrior to the arrival of Pakehā to the shores of Aotearoa, Māori retained and transmitted their histories, genealogies and protocols orally through such mediums as song and chant. The intracacies of the information held was such that every aspect of the Māori culture had its assigned expert whose job was to both retain and pass on their area of expertise. The settlement of Pakehā saw a change in how information was stored and disseminated, with a number of ethnographers, surveyors and historians recording accounts given to them from various Māori sources in written form. The main motivation for this at the time was to secure the information and cultural practises of a people who were deemed to be a dying race.
The implication that Māori were close to extinction was in vain, as many resisted against the gradual assimilation of Aotearoa (New Zealand) by the new foreign immigrants. The subsequent annexation of Aotearoa under British colonial rule eventually led to war against Māori, as Māori attempted to protect and retain both their lands and their identity. The result of the war led to a great loss of Māori lands, lives, and most importantly – identity.
Within Taranaki the Ngāti Rāhiri Hapū fought many generations for the right to stand unified as a people. Although they can be regarded as a small coastal hapū entity, they are at the forefront of maintaining and asserting their rangatiratanga status within today’s society. At the centre of the proclamation of rights and entitlement within their ancestral lands, questions have been raised that, for a number of generations, had baffled the likes of Elsdon Best and S. Percy Smith, as many sought to find answers regarding the true origins of Ngāti Rāhiri.
The impetus in undertaking this research is to ascertain who this prominent ancestor Rāhiri is from both a Ngā Puhi and Taranaki perspective, and investigate how these combined histories assist in the assertion of self by the Ngāti Rāhiri ki Taranaki people. By undertaking a critical review and analysis of literature, court minute records, hapū documents, proverbs, histories and knowledge from tribal elders pertaining to Rāhiri, this researcher will endeavour to provide and present relevant information and evidence, in a cohesive format, to show the close ancestral ties and affiliations between the two peoples. Furthermore, it is hoped that the research findings presented within this body of work may provide a significant contribution to the descendants of the Ngāti Rāhiri ki Taranaki Hapū, as they continue to assert their mana and rangatiratanga through the knowledge and understanding of self, when posed with the question - Ko wai a Ngāti Rāhiri
Disaster Response for Effective Mapping and Wayfinding
No full textThe research focuses on guiding the affected population towards a safe location in a disaster area by utilizing their self-help capacity with prevalent mobile technology. In contrast to the traditional centralized information management systems for disaster response, this research proposes a decen- tralized computer-supported management system in which affected people can lead themselves to safety and simultaneously serve as field sensors that share information about the disaster situation. A literature study together with contextual inquiries (field observations) were first conducted to analyse and identify existing problematic areas in order to envision a feasible, efficient and effective system. Based on literature from the field of disaster sociology and humanitarian operation experience, it was clear that the affected people in a disaster are not simply helpless victims; instead, they consist of capable human beings who tend to act rationally and proactively in a united and helpful manner. In times of collective stress, they are even able to creatively use whatever means of technology are at hand. This group forms the majority of the population that is affected by a disaster. They are distributed over the disaster area and witness the disaster first hand. As a result, these individuals form a massive potential resource for collecting first hand knowledge about the disaster. Field observations indicated that tailored mobile navigation support is lacking. Likewise, situation map-map- ping support has appeared to be limited, fragmented, and funnelled to one “plotter”. The literature and field observations showed that there is a need for (1) navigation support of the affected people, (2) collaborative map-making support, and (3) the integration of these support functions into one informa- tion system to establish a harmonized, effective, and safe, disaster response. As part of the research, prototypes of these two support functions and the integrated system were developed and tested in both controlled environments and out in the field. Major disaster events can significantly change an area, render earlier geo- graphical data obsolete, and make damaged infrastructure hazardous to the affected people. In order to minimize public exposure to such dangerous conditions, which prevail in disaster areas, the affected people need to be guided to a safer location. Thus, a navigation system that provides sufficient and flexible guidance given the altered environment in the disaster area is critical in these situations. The first study was a field experiment, tested a handheld navigation solu- tion that pointed toward the direction of a destination and elementary navi- gational cues. The results suggested that a rudimentary navigation cue in the form of an arrow was sufficient to guide an individual towards a specific destination. Moreover, additional navigation cues such as the distance or the time to a destination gave additional support by making it easier for a person to follow the guidance. However, in order to provide adequate navigational support, an up-to-date presentation of the post-disaster situation is desirable. Especially as a map is usually needed to represent complex situations. For example, during the field observations of USAR.nl in the Czech Republic, the rescuers sketched and updated a map (drawn on the wall) with a spray can to represent the rescue situation and their activity outcomes over time. The command post was informed about the situation however by audio (tel- ephone) communication. In a disaster with widespread damage, the disaster situation needs to be rapidly assessed. However, the traditional centralized mechanism of gathering this kind of information is regarded as inefficient and can result in an inaccurate and outdated situation map. These ineffi- ciencies stem from: (1) the use of an unsuitable communication modality to relay spatial information (e.g. audio), (2) limited emergency resources that collect this kind of information, and (3) the hierarchical and chain report- ing structure in the organization of the map-making process. To overcome these inefficiencies, this research also focuses on a distributed approach that utilizes the affected people for collecting situation data in the field and using additional modalities of communication. This led to the second study, which investigated the construction of a shared situation map using a collaborative mechanism. This study was conducted in a controlled laboratory environment. The first results demonstrated that if the contribution from each individual is not balanced then collaborative map-making can result in a joint map that is worse than the underlying in- dividual maps. Based on this result, a method of explicitly showing confi- dence information was prototyped in the subsequent experiment. The results showed that the quantity and quality of the information in the collaborative maps was better than the individual maps. It was concluded that a visual shared map can complement the auditory communication during situation map-making and that explicitly rating objects and events in the map with a confidence level significantly enhanced the discussion process. Finally, the third empirical study was an extensive controlled field study where Delft was converted into a disaster playground. Several participants played simultaneously different roles (the affected people and the operator) located at multiple locations (in the field and in the information center) while using multiple devices (mobile phone, desktop computer) and applications (mobile client, server, and simulation). The aim of this study was to compare the proposed system with the traditional centralized system. The result of this study demonstrated that the proposed system was superior in (1) guiding the affected people safely to their destination, (2) helping operators in achiev- ing a higher situational awareness, and (3) lowering operator workload. To conclude, this research proposes a participatory distributed mechanism which involves the affected people to improve the disaster response. The system harvests the capabilities of the affected people as distributed active sensors for assessing disaster situations. In this way, they can help them- selves to safety while helping to rapidly construct a clear image of the dis- aster without burdening the already overwhelmed rescue services. The study showed that this mechanism might reduce the workload of the disaster re- sponders and may improve the effectiveness of the disaster response process. With better situational awareness of the disaster area, humanitarian aid and rescue activities can be conducted more effectively and victims can be saved faster than before. Thus, the proposed system in this thesis can form the foundation of an efficient next generation disaster response system.MediamaticsElectrical Engineering, Mathematics and Computer Scienc
Fabrikage Butanon-2
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
Exciton and charge carrier dynamics in semiconductor nanorods and nanoplatelets
No full textChemE/Chemical EngineeringApplied Science
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