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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

An investigation into the axial capacity of eccentrically loaded concrete filled double skin tube columns

Koen, Johan Alexander 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Concrete filled double skin tube (CFDST) columns is a new method of column construction. CFDST columns consists of two steel hollow sections, one inside the other, concentrically aligned. The cross-sections of the two hollow sections does not have to be the same shape. Concrete is cast in between the two hollow sections resulting in a CFDST. This study only considers CFDST columns constructed with circular steel hollow sections. The advantages of CFDST construction include: ● The inner and outer steel hollow sections replaces the traditional steel reinforcement that would be used in a normal reinforced concrete column. This reduces the construction time since there is no need to construct a reinforcing cage. ● The steel hollow sections acts as a stay in place formwork, eliminating the need for traditional formwork. This also reduces construction time. ● The steel hollow sections confine the concrete, making it more ductile and increasing its yield strength. The objective of this study is to identify methods that can predict the axial capacity of eccentrically loaded circular CFDST columns. Methods chosen for the investigation are: 1. Finite element model (FEM). A model was developed to predict the behaviour of eccentrically loaded CFDST columns. The FE model uses a concrete material model proposed in literature for stub columns. The aim was to determine whether the material model is suited for this application. 2. The failure load of CFDST columns under concentric loading was calculated using a model obtained in literature. These capacities were compared to the experimental test results of eccentrically loaded CFDST columns to establish a correlation. This study found that the concrete material model used does not adequately capture the behaviour resulting in the axial response of the column being too stiff. The difference between the eccentrically loaded experimental test results and the calculated concentrically loaded capacity showed a clear trend that could be used to predict the capacity of eccentrically loaded CFDST columns. / AFRIKAANSE OPSOMMING: Beton-gevulde dubbel laag pyp (BGDLP) kolomme is ‘n nuwe metode van kolom konstruksie. BGDLP kolomme bestaan uit twee staal pyp snitte, die een binne die ander geplaas met hul middelpunte opgelyn, die dwarssnit van die twee pype hoef nie dieselfde vorm te wees nie. Beton word dan in die wand tussen die twee pyp snitte gegiet. Die resultaat is ‘n hol beton snit. Hierdie studie handel slegs oor BGDLP kolomme wat met ronde pyp snitte verwaardig is. Die volgende voordele kan aan BGDLP toegeken word: ● Die binne en buite staalpype vervang die tradisionele staal bewapening was in normale bewapende-beton gebruik sou word. Dus verminder dit die tyd wat dit sal neem om die kolom op te rig. ● Die staalpypsnitte is ook permanente vormwerk. Dit doen dus weg met die gebruik van normale bekisting, wat ook konstruksie tyd spaar. ● Die buite-staalpypsnit bekamp die uitsetting van die beton onder las. Hierdie bekamping veroorsaak dat die beton se gedrag meer daktiel is en ‘n hoër falings spanning kan bereik. Die doel van die studie is om metodes te identifiseer wat gebruik kan word om die aksiale kapasiteit onder eksentriese laste van BGDLP kolomme te bepaal. Twee metodes was gekies: 1. Eindige element model. ‘n Model was ontwikkel om die gedrag van BGDLP kolomme te voorspel. Die mikpunt was om te bepaal of ‘n beton materiaal gedrag model vanuit die literatuur gebruik kan word om BGDLP kolomme te modelleer. 2. Die swiglas van BGDLP kolomme onder konsentriese belasting was bereken vanaf vergelykings uit die literatuur. Hierdie swiglaste was vergelyk met die eksperimentele toets resultate vir eksentriese belaste BGDLP kolomme om ‘n korrelasie te vind. Hierdie studie het bewys dat die beton materiaal model uit die literatuur kan nie gebruik word om die swiglaste van BGDLP kolomme te bepaal nie. Die model het die gedrag te styf gemodelleer. Die verskil tussen die berekende konsentriese belaste swiglas en die eksperimentele resultate van eksentriese BGDLP kolomme was voorspelbaar en kan gebruik word om die swiglas van eksentriese belaste BGDLP kolomme te voorspel.
352

Electrical energy analysis in nine countries of Europe, with focus on wind power and other renewable energy sources

Ghanian, Nariman, Farhang Esfahani, William Mohammad, Hassan, Muhammad Touqeer Ul January 2015 (has links)
This thesis has been written for the Bachelor degree in Electrical Engineering held at Blekinge Tekniska Högskola Karlskrona, Sweden. The basis of this thesis is a statistical analysis of the electrical energy situation with emphasis on contribution of wind power and other renewable energy in electricity production in the European area and key countries.   The main parameters, which considered in this thesis are electricity production and consumption, installed capacity trends and also the operation of renewable sources, especially wind power in gross electricity generation. Meanwhile, the whole date and materials are based on real values and investigated from the latest publications of governments and energy agencies of European union and key countries.   The target of European renewable energy is that the member countries must achieve at least 20 percent of final energy consumption from renewable energy by 2020. Germany, United Kingdom, Spain and France and Portugal are members of the highest consumers of electricity in the Europe and still the main source of electrical production in these countries are fossil fuels, the main challenge is that they should start to shutting down the traditional power plant and improve the infrastructure for installing the renewable electrical capacity instead.   According to the statistics, many of the European countries such as United Kingdom, Germany, Spain, Denmark and Sweden have started up to use the renewable energy to produce the electrical energy, but their governments have special keen eye for investment in the wind energy sector. Wind power grew sharply during the past decades in Europe and becoming vital every coming day in comparison to other renewable energy, since the low cost of electricity can be granted through a small investment and relies on the wind blowing compared to the conventional electricity generation sources. The diagrams demonstrate the wind power has a main portion to producing the electrical energy and every year a considerable amount of installed capacity is added to the total electrical grid.   In addition, the expansion of renewable energy  to achieve the high percent of electrical production requires  the improvement of  infrastructure such as ecological research and high coordination between different organizations. Also, the electrical generation cannot be constant, and in winter the overall consumption and demand for electricity increases all over Europe. The exploitation of some renewable sources such as solar and wind power for electrical production can have fluctuation due to the weather condition and wind speed, which can affect the overall generation to the electrical grid.   Therefore, the balancing of several renewable sources in different seasons,  needs the unique power management for reliable electrical production. In this trend, Norway is a successful country in Europe that uses over 90 percent of  renewable sources for total electrical generation. The thesis has covered these challenges and how they are overcoming these issues.
353

Spetsbärförmåga hos betongpålar slagna i friktionsjord

Elvin, Lena, Dangré, Markus January 2004 (has links)
<p>The purpose of this study was to build a database for point-bearing piles in dense noncohesive soil, predominantly moraine. Further, the database was analysed and areas with difficult geotechnical conditions was identified.</p><p>The database includes for point-bearing piles driven to refusal in moraine. Piles with mainly shaft friction have been excluded. Only concrete piles have been included. Geographically the database covers almost all geotechnical conditions of Sweden. The total amount of piling projects is 110 and the total amount of piles is 600.</p><p>For contractors, foundation work is usually connected with a lot of uncertainty and risk, concerning the estimating of time and cost. During the design stage of foundation construction the database can be a useful tool to estimate suitable loads on the piles.</p><p>The data was analysed further with different statistical method. Possible reasons for low bearing capacity, in some projects, have also been investigated.</p> / <p>Syftet med examensarbetet är att upprätta en databas över spetsburna pålar fastslagna i friktionsjord och morän. Vidare skall databasen analyseras för att hitta styrande parametrar samt även hitta områden med problematisk geoteknik.</p><p>Databasen omfattar spetsburna pålar som stoppslås i friktionsjord. Pålar som i huvudsak är mantelburna har uteslutits. Endast betongpålar har tagits med. Geografiskt omfattar databasen i stort sett hela Sverige. Totalt innehåller databasen 110 projekt med sammanlagt över 600 pålar.</p><p>För entreprenörer i byggbranschen är grundläggningsarbetet ofta förknippat med ekonomiska risker och osäkerhet gällande omfattning och tidsåtgång. Vid dimensionering av grundläggningsarbeten kan databasen vara till stor hjälp för att bestämma lämpliga lastnivåer. Mängden slagningsarbete och risken för bortslagna pålar kan lättare uppskattas.</p><p>Först analyserades olika påltyper utan ytterligare urvalskriterier. Vikten av att filtrera informationen blev då tydlig, eftersom resultatet blev svårtolkat och inga markanta samband kunde urskiljas. Med databasen som grund har materialet vidare analyserats med hjälp av statistiska metoder. Orsaken till låga bärförmågor vid ett urval av projekt har även kartlagts.</p>
354

Benchmarking the Resilience of Organisations

Stephenson, Amy Victoria January 2010 (has links)
Our world is more technologically advanced and interdependent, risks are increasingly shared across local, regional and national boundaries and we are more culturally diverse than ever before. As a result, communities are increasingly confronted with emergencies and crises which challenge their social and economic stability. To be resilient, communities rely on services and employment provided by organisations, to enable them to plan for, respond to, and recover from emergencies and crises. However organisational and community resilience are two sides of the same coin; if organisations are not prepared to respond to emergencies and crises, communities too are not prepared. Resilient organisations are also better poised to develop competitive advantage. However despite the potential business and performance rewards of becoming more resilient, organisations struggle to prioritise resilience and to allocate resources to resilience, which could be put to more immediate use. To enable organisations to invest in their resilience, the business case for resilience must be better than the case for new equipment or new staff. This thesis develops a methodology and survey tool for measuring and benchmarking organisational resilience. Previous qualitative case study research is reviewed and operationalised as a resilience measurement tool. The tool is tested on a random sample of Auckland organisations and factor analysis is used to further develop the instrument. The resilience benchmarking methodology is designed to guide organisations’ use of the resilience measurement tool and its incorporation into business-as-usual continuous improvement. Significant contributions of this thesis include a new model of organisational resilience, the resilience measurement tool, and the resilience benchmarking methodology. Together these outputs translate the concept of resilience for organisations and provide information on resilience strengths and weaknesses that enable them to proactively address their resilience and to develop a business case for resilience investment.
355

Environmental Capacity of Local Streets with Street Treatments

Leckie, Andrew Francis January 2012 (has links)
“I want my street to be like an extension to my driveway, where the kids can play safely and where the traffic does not bother us,” said one resident. Another said that she “likes traffic... We live in a city.” This gives an idea of the broad range of opinions and views that exist on traffic. Traffic in local streets in a concern for residential amenity. There is always conflict between the residential amenity and traffic access functions of local streets. There is much debate on what a true local road is. The concept of environmental capacity was developed to identify a suitable maximum traffic volume on local streets, without overly adversely affecting residents. It was first introduced by Buchanan and Appleyard in separate research in the 1960s. Both men settled on thresholds of 2,000-3,000 vehicles per day. Chesterman, in 2009, carried out a study in Christchurch, surveying residents on four local streets with varying traffic volumes. He found residents living on busier streets felt that their streets were busier, noisier and less safe. There was also an increasing trend for these residents to have their houses turned away from the street and they tended to have less personal involvement with their neighbours. He found that perhaps a more suitable environmental capacity estimate was between 1,500 and 2,000 vehicles per day. This study looked at further Christchurch streets, this time with street treatments, such as street calming and tree plantings, aiming to find an environmental capacity for these streets as well as seeing whether the street treatments affected the perceived environmental capacity. As well as reinforcing most of the conclusions found by Chesterman, a higher environmental capacity of around 2,000 vehicles per day was found for the surveyed streets. This suggests that indeed, street treatments such as those used in the surveyed streets can increase the environmental capacity, which has implications for local councils who want to maintain road traffic carrying capabilities without having unsatisfied residents.
356

Evaluation of Generation Capacity Adequacy using System Dynamics

Syed Jalal, Thahirah binti January 2013 (has links)
Most power market structures have been developed and implemented without being tested, causing major problems such as shortages and blackouts. The main cause for these problems is the inability of some markets to provide adequate stimulus for new generation investments. The installed generation capacity goes through boom and bust cycles, exposing consumers to potential shortages during long bust periods. With the realisation that the power market has a strong interaction with generation investment, a System Dynamics (SD) model is developed to study how the market interacts with generation expansion. The SD model also allows for market structures and policies to be evaluated before being implemented. It can be an important tool in ensuring that generation expansion is done optimally without the expense of energy security. New Zealand’s generation capacity is no exception to the boom and bust trend. Since the commencement of the New Zealand Energy Market (NZEM) in October 1996, energy shortages occurred in the winters of 2001, 2003 and 2008. As a case study, an SD model is developed to study the NZEM. The results show that under some forecasted scenarios, New Zealand is susceptible to future energy shortages due to boom and bust cycles in the generation capacity.
357

Ribotas pakaltinamumas ir jo reikšmė / Diminished capacity and its importance

Stankus, Marius 25 November 2010 (has links)
Darbe nagrinėjamas riboto pakaltinamumo institutas Lietuvos Respublikos baudžiamojoje teisėje: jo istorinė raida, atsiradimo ypatumai, turinys bei reikšmė, taip pat nustatymo klausimai bei problemos. Kadangi šis institutas pakankamai platus ir apima ne vien jo turinį sudarančius kriterijus ir jų požymius, tačiau ir apibrėžia asmenų baudžiamąją atsakomybę bei numato galimybę taikyti baudžiamojo poveikio ar medicinos prievartos priemones, apsiribota tyrinėjamo objekto nagrinėjimu Lietuvos baudžiamojoje teisėje, trumpai apžvelgiant kitose valstybėse įtvirtintus panašius institutus. Ypatingas dėmesys darbe skiriamas riboto pakaltinamumo turinį sudarančių medicininio ir juridinio kriterijų atskleidimui, jų nustatymo ypatumams ir būdams, aptariami dažniausiai pasitaikantys psichikos sutrikimai, lemiantys minėtų kriterijų nustatymą. Be to, nagrinėjamas riboto pakaltinamumo ir amžiaus santykis, socialinio nebrandumo priskyrimas riboto pakaltinamumo medicininiam kriterijui, atskirai aptariamos afekto ir pogimdyvinė psichofiziologinė būsenos, jų santykis su ribotu pakaltinamumu bei Lietuvos Respublikos baudžiamajame kodekse įtvirtintos, su minėtomis būsenomis siejamos nusikalstamos veikos. Lietuvos baudžiamojoje teisėje riboto pakaltinamumo institutas pakankamai „jaunas,“ todėl jo taikymo praktika vis dar formuojasi. Remiantis Lietuvos teismų praktika, darbe stengtasi iškelti minėto instituto taikyme bei reglamentavime pastebėtas problemas, pasiūlyti jų sprendimo variantus. / This article analyses diminished capacity in Lithuanian penal law: its historical development, peculiarities of instilment, its content, its importance, also questions of its evaluation and occurring problems. Whereas the institution of diminished capacity is quite wide, it includes not only its content, content’s criteria ant their features, but it also determines criminal liability of an individual, foresees the application of punitive and forced medical measures, therefore in this article diminished capacity is analyzed within limits of Lithuanian penal law, with brief overlook of similar institutions implemented in penal law of other countries. Special attention is paid to the medical and juridical criteria of the content of diminished capacity, the disclosure of their content, peculiarities and means of their evaluation. Due to that most common mental affections that determine the measurement of above-mentioned criteria are discussed. Moreover the relation of age and diminished capacity and attribution of social immaturity to the medical criterion are researched. Apart of all mentioned above, diminished capacity relations with the state of affect and special postnatal state of women is analyzed likewise crimes associated with aforesaid states are also scrutinized. The institution of diminished capacity in Lithuanian penal law is quite „young“ therefore its practice of its implementation is still shaped. Also, according to the practise of Lithuanian courts, the main... [to full text]
358

A study of predicitive capacity and working memory in mild Alzheimer's disease and normal controls using saccadic eye movements

Ruthirakuhan, MYURI 22 May 2013 (has links)
Alzheimer’s disease (AD) is a neurodegenerative disorder with no existing cure. Since cognitive control influences saccade behaviour, saccades provide a valuable tool when studying cognitive changes in healthy and pathological aging. This thesis aims to evaluate differences in predictive capacity and working memory between cognitively normal older adults (NC) and mild AD patients using customized saccade paradigms and a battery of neuropsychological tests. In the predictive paradigm, we hypothesize that AD participants would display a decreased level of prediction, predictive capacity and learning capacity. In the memory-guided paradigm, we hypothesize that AD participants would have a decreased ability to maintain fixation and capacity to retain information and reproduce it correctly. Overall, we found that in the predictive paradigm, NC displayed a greater degree of prediction than AD participants. However, both groups had an optimal level of prediction at intermediate inter-stimulus intervals (ISI) (750 and 1000 ms). As ISI increased, both groups, although more so in AD, elicited a greater proportion of SRTs below -200 ms and -400 ms. This may suggest that as ISI increased, participants switched from a predictive to an anticipatory/guessing strategy. At an ISI of 500 ms, NC’s learning capacity was greater than AD participants. Cognitive scores of neuropsychological tests did not correlate with learning capacity in NC. However, learning capacity in AD participants was positively correlated with working memory capacity and attentional control. The memory-guided paradigm revealed AD participants completed less viable trials, less correct trials, and had more combined directional and timing errors than NC. Cognitive correlations showed that NC’s working memory capacity positively correlated with the frequency of correct trials, whilst negatively correlating with saccade errors. Since AD participants completed 10% of viable trials correctly, the task may have been too difficult for AD participants to comprehend, rendering correlations invalid. These findings suggest that although the predictive paradigm does not solely assess for prediction, it may provide a measure to cognitively differentiate NC from AD patients, and detect AD severity. Since the memory-guided paradigm may be too difficult for AD participants, it may provide a better indicator of cognitive changes associated with healthy aging. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-05-21 18:54:19.492
359

The role of local economic development in building capacity and growth for small, medium and micro enterprises in Sedibeng District Municipality / Mavi Sintu

Mavi, Sintu January 2012 (has links)
South Africa as a developing country experienced high levels of poverty and unemployment. These levels emanate from skills gap and low literacy rate in the townships populated by low income households. To an extent some households lacked access to participate in the economic sector, resulting from fragmented policies and apartheid regime. The lack of participation among the households placed pressure on government. These problems forced the state to provide social protection (grants). Such allowances are expensive especially where there are fewer opportunities for employment activities. The promotion of entrepreneurship and small business remains an important priority of the government of South Africa. The South African government is acknowledged for its commitments to ensure that small businesses progressively contribute to growth and performance of the South African economy. Globally, numerous policy legislative frameworks have been developed to support the SMMEs. This study aimed to discover the support given to the SMMEs by the South African government. In particular, the study is situated within the SMMEs in the SDM. The hypothesis for this study is premised on the fact that SMME`s can contribute immensely to job creation. The outcomes of this argument relies on the provisions based on a conducive environment which can enable the SMME`s to thrive. This statement was validated by means of literature review, interviews and site visits. This study found that the SMMEs are indeed the cornerstone of job creation and for sustainable livelihoods. LED programmes can create more jobs through the SMME sector. Literature worldwide confirms that the SMMEs are vital in creating employment opportunities. This research also confirmed that this is possible only if the environment in which SMMEs operate in is favourable for the SMMEs to prosper. In this regard many policy documents were developed to emphasize the stance of government to develop, grow and capacitate SMMEs in South Africa. It is indeed true that the LED can be used to grow and capacitate SMMEs in South Africa. Despite the progress being made on the development of the SMMEs, few issues need to be taken care off. The municipality indicated that there are no monitoring procedures in place which make it difficult to measure the infectiveness of their interventions and they further pointed out that they are working on the matter. The measurement of these milestones is not properly recorded to inform future generations. It is suggested that more research should be emphasised on the SMME sector, especially being the mandate of the municipality. / Thesis (M. Development and Management (Public Management and Government))--North-West University, Vaal Triangle Campus, 2013
360

Sorption of Ni and Eu to granitic rocks and minerals

Sameh, Ebong F. January 2011 (has links)
The work presented in this thesis is divided into two parts. The first part is the sorption of Ni and Eu to granitic materials, and cation exchange capacity measurements for powdered and intact samples. The second part is method development on autoradiography. In the first part, static batch sorption experiments were carried out to study the relative sorption properties of different granitic rocks and minerals. Experimental data were described using non-electrostatic correction models such as the Langmuir, Freundlich and Linear models. Sorption data obtained for sorption in a constant pH environment and variable metal concentration were used to test the Component Additive Model (CAM). Sorption test studies carried out using energy dispersive X-ray microanalysis were used to map the sorption of Eu on an intact sample. The results showed the CAM was applicable for Ni sorption to BG but that it was not applicable for Eu sorption to any of the granitic rocks studied. The sorption data fitted the CAM in the following order; BG (1) > GA (0.7) > RG (0.5) > GG (0.2), GrG (0.2) for Ni sorption and RG (0.7) > BG (0.4) > GA (0.2), GG (0.2), GrG (0.2) for Eu sorption to the different granitic rocks. Values in brackets represent the ratio of Rd-predicted/Rd-calculated. Results from the application of the CAM showed it was not possible to predict the Rd of the bulk sample from the component minerals. Desorption studies at constant pH were analysed by calculating the hysteresis H. The results showed that the higher the Rd the higher the hysteresis. Surface complexation using JChess Geochemical Code was used to obtain surface complexation parameters for the metal-solid complex for sorption in variable pH and constant metal concentration. Experimental data were described by the mass action law to obtained proton stoichiometry at which the sorption edge is defined. Results showed the presence of NaCl decreased the sorption of Ni, and increased the sorption of Eu. Sorption kinetics experiments in different carbonate complexing environments were carried out to study the effect of carbonate on Eu sorption capacity and rate of sorption. Data were fitted to first and second order kinetic models to investigate the sorption rates. Results showed the sorption to be fast initially before reaching a steady state after more than 200 hours of equilibration. Kinetic data confirmed the low sorption capacity observed for quartz. Data obtained for sorption in a mixed radionuclide system were modelled using the Linear model and the surface complexation model. The surface complexation constants are correlated to the Rd values obtained from the linear sorption isotherms. Modelling the results using Rdmix and Rdsing showed that sorption was suppressed in a mixed system, with no effect observed for sorption to feldspar in single and mixed systems. Cation exchange capacity (CEC) measurements were undertaken to deduce a correlation between the CEC of powdered rock samples and intact sample using rock beakers developed from the British Geological Survey by applying the Bascomb method in which the pH was buffered to pH 8.1. Normalising the results using the surface area showed that the CEC of the rock beakers was 6 orders of magnitude greater than that of the powdered sample. In the second part, a method for differentiating two or more radionuclides using storage phosphor imaging plates coupled with the Storm Scanner system was tested. Initial results showed that it is possible to differentiate one radionuclide from another in a mixed system using different levels of shielding.

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