Este trabalho mostra o desenvolvimento de um procedimento de ensaio para materiais de fricção a ser aplicado em um tribômetro, tendo como característica principal frenagem com velocidade constante e elevadas temperaturas envolvidas. Desenvolveu-se uma metodologia simples, com etapas e parâmetros definidos a partir das características principais do tribômetro utilizado e da temperatura limite desejada no final de cada frenagem. Ao todo, três etapas distintas formam a estrutura básica do procedimento de ensaio: assentamento, caracterização e etapas com altas temperaturas. Para determinação dos parâmetros preliminares de cada uma das etapas envolvidas, utilizou-se amostras de formulação semelhantes a pastilhas de freio de veículos e também amostras com número reduzido de componentes. Para provar a eficácia do método proposto, foram utilizados três materiais com formulações distintas, sendo dois com uma variedade maior de componentes e um notadamente mais simples. Na etapa de assentamento, observou-se a estabilização do coeficiente de atrito das amostras enquanto que nas etapas de caracterização, observou-se a recuperação do coeficiente de atrito entre as etapas de temperatura. Para os estágios de temperatura elevada realizados, foi possível verificar a diferença de comportamento dos materiais utilizados, sendo o coeficiente de atrito menor na primeira etapa de temperatura que na segunda. Entretanto, os resultados também indicaram que alguns dos parâmetros preliminares escolhidos para as etapas de assentamento e temperatura não se mostraram satisfatórios, implicando em mudanças para a versão final da metodologia de ensaio apresentada. / This work presents the development of a testing procedure to evaluate the fiction and wear of friction materials to be applied in a tribometer, with main characteristic braking with constant speed and high temperatures. It was developed a simple methodology, with steps and parameters defined from the main characteristics of the used tribometer and the final limit temperature desired at the end of each braking. Totally, three different stages form the basic structure of the testing procedure: bedding-in, characterization and stages with high temperature. To determinate de primary parameters of each stage, it was used samples with similar formulation as vehicles friction pads and also samples with reduced number of components. To prove the efficiency of the proposed methodology, were used three different friction materials, being two with a large variability of components and a simple one. The bedding-in and the characterization stages showed the stabilization and the recuperation of the friction coefficient of the samples, respectively. After each high temperature stages, it was possible to verify the difference of the used materials, being the friction coefficient lower in the first temperature stage than the second one. However, these results also showed that some chosen primary parameters for the bedding-in and high temperature stages were not satisfactory, implicating in changes to the final procedure version.

Este trabalho mostra o desenvolvimento de um procedimento de ensaio para materiais de fricção a ser aplicado em um tribômetro, tendo como característica principal frenagem com velocidade constante e elevadas temperaturas envolvidas. Desenvolveu-se uma metodologia simples, com etapas e parâmetros definidos a partir das características principais do tribômetro utilizado e da temperatura limite desejada no final de cada frenagem. Ao todo, três etapas distintas formam a estrutura básica do procedimento de ensaio: assentamento, caracterização e etapas com altas temperaturas. Para determinação dos parâmetros preliminares de cada uma das etapas envolvidas, utilizou-se amostras de formulação semelhantes a pastilhas de freio de veículos e também amostras com número reduzido de componentes. Para provar a eficácia do método proposto, foram utilizados três materiais com formulações distintas, sendo dois com uma variedade maior de componentes e um notadamente mais simples. Na etapa de assentamento, observou-se a estabilização do coeficiente de atrito das amostras enquanto que nas etapas de caracterização, observou-se a recuperação do coeficiente de atrito entre as etapas de temperatura. Para os estágios de temperatura elevada realizados, foi possível verificar a diferença de comportamento dos materiais utilizados, sendo o coeficiente de atrito menor na primeira etapa de temperatura que na segunda. Entretanto, os resultados também indicaram que alguns dos parâmetros preliminares escolhidos para as etapas de assentamento e temperatura não se mostraram satisfatórios, implicando em mudanças para a versão final da metodologia de ensaio apresentada. / This work presents the development of a testing procedure to evaluate the fiction and wear of friction materials to be applied in a tribometer, with main characteristic braking with constant speed and high temperatures. It was developed a simple methodology, with steps and parameters defined from the main characteristics of the used tribometer and the final limit temperature desired at the end of each braking. Totally, three different stages form the basic structure of the testing procedure: bedding-in, characterization and stages with high temperature. To determinate de primary parameters of each stage, it was used samples with similar formulation as vehicles friction pads and also samples with reduced number of components. To prove the efficiency of the proposed methodology, were used three different friction materials, being two with a large variability of components and a simple one. The bedding-in and the characterization stages showed the stabilization and the recuperation of the friction coefficient of the samples, respectively. After each high temperature stages, it was possible to verify the difference of the used materials, being the friction coefficient lower in the first temperature stage than the second one. However, these results also showed that some chosen primary parameters for the bedding-in and high temperature stages were not satisfactory, implicating in changes to the final procedure version.

Este trabalho mostra o desenvolvimento de um procedimento de ensaio para materiais de fricção a ser aplicado em um tribômetro, tendo como característica principal frenagem com velocidade constante e elevadas temperaturas envolvidas. Desenvolveu-se uma metodologia simples, com etapas e parâmetros definidos a partir das características principais do tribômetro utilizado e da temperatura limite desejada no final de cada frenagem. Ao todo, três etapas distintas formam a estrutura básica do procedimento de ensaio: assentamento, caracterização e etapas com altas temperaturas. Para determinação dos parâmetros preliminares de cada uma das etapas envolvidas, utilizou-se amostras de formulação semelhantes a pastilhas de freio de veículos e também amostras com número reduzido de componentes. Para provar a eficácia do método proposto, foram utilizados três materiais com formulações distintas, sendo dois com uma variedade maior de componentes e um notadamente mais simples. Na etapa de assentamento, observou-se a estabilização do coeficiente de atrito das amostras enquanto que nas etapas de caracterização, observou-se a recuperação do coeficiente de atrito entre as etapas de temperatura. Para os estágios de temperatura elevada realizados, foi possível verificar a diferença de comportamento dos materiais utilizados, sendo o coeficiente de atrito menor na primeira etapa de temperatura que na segunda. Entretanto, os resultados também indicaram que alguns dos parâmetros preliminares escolhidos para as etapas de assentamento e temperatura não se mostraram satisfatórios, implicando em mudanças para a versão final da metodologia de ensaio apresentada. / This work presents the development of a testing procedure to evaluate the fiction and wear of friction materials to be applied in a tribometer, with main characteristic braking with constant speed and high temperatures. It was developed a simple methodology, with steps and parameters defined from the main characteristics of the used tribometer and the final limit temperature desired at the end of each braking. Totally, three different stages form the basic structure of the testing procedure: bedding-in, characterization and stages with high temperature. To determinate de primary parameters of each stage, it was used samples with similar formulation as vehicles friction pads and also samples with reduced number of components. To prove the efficiency of the proposed methodology, were used three different friction materials, being two with a large variability of components and a simple one. The bedding-in and the characterization stages showed the stabilization and the recuperation of the friction coefficient of the samples, respectively. After each high temperature stages, it was possible to verify the difference of the used materials, being the friction coefficient lower in the first temperature stage than the second one. However, these results also showed that some chosen primary parameters for the bedding-in and high temperature stages were not satisfactory, implicating in changes to the final procedure version.

No / Purpose: To develop a perimetric test strategy, Structure Estimation of Minimum Uncertainty (SEMU), that uses structural information to drive stimulus choices. Methods: Structure Estimation of Minimum Uncertainty uses retinal nerve fiber layer (RNFL) thickness data as measured by optical coherence tomography to predict perimetric sensitivity. This prediction is used to set suprathreshold levels that then alter a prior probability distribution of the final test output. Using computer simulation, we studied SEMU’s performance under three different patient error response conditions: No Error, Typical False Positive errors, and Extremely Unreliable patients. In experiment 1, SEMU was compared with an existing suprathreshold cum thresholding combination test procedure, Estimation of Minimum Uncertainty (EMU), on single visual field locations. We used these results to finalize SEMU parameters. In experiment 2, SEMU was compared with full threshold (FT) on 163 glaucomatous visual fields. Results: On individual locations, SEMU has similar accuracy to EMU, but is, on average, one presentation faster than EMU. For the typical false-positive error condition, SEMU has significantly lower error compared with FT (SEMU average 0.33 dB lower; p < 0.001) and the 90% measured sensitivity range for SEMU is also smaller than that for FT. For unreliable patients, however, FT has lower mean and SD of error. Structure Estimation of Minimum Uncertainty makes significantly fewer presentations than FT (1.08 presentation on average fewer in a typical false-positive condition; p < 0.001). Assuming that a location in the field is marked abnormal if it falls below the 5th percentile of normal, SEMU has a false-positive rate of less than 10% for all error conditions compared with FT’s rate of 20% or more. Conclusions: On average, simulations show that using RNFL information to guide stimulus placement in a perimetric test procedure maintains accuracy, improves precision, and decreases test duration for patients with less than 15% false-positive rates.

It is widely known that the textile industry is a large polluter and that fast fashion in particular has sustainability issues. Meanwhile, second-hand stores struggle to sell their products in Europe, leading to most clothes either being exported and/or landfilled. This issue is partially driven by costumers not knowing what performance they can expect from second-hand products. In this study, the water repellency of used hardshell jackets will be evaluated with the goal of proving that second-hand products still have enough performance for reuse. This implies that prolonging the lifetime of waterproof jackets is possible, which will reduce CO2 emissions. Various standards are evaluated and a new method, dubbed the stream impact test is defined, trialed and compared to results from the ISO 4920 spray test. In order to estimate the full potential of reusing jackets, the effects of rejuvenating used jackets, by washing the mand using water repellent spray, are also tested. The current standards for aging fabric used by the industry to prove the durability of water repellency will be evaluated using both the ISO 4920 spray test and the new stream impact test. The testing concludes that while the new method has certain issues, it does achieve it’s core objectives and provides a new perspective on the water repellency of new, used and rejuvenated fabrics. It also shows that, on average, rejuvenating jackets has a good effect on the water repellency of jackets and that. During the testing of used jackets with the stream impact method, jackets are found with water repellent properties between those of new fabric and very old fabric. This suggests that there are jackets with a lot of technical performance left that are discarded, which would be ideal for reuse and allowing the clothing industry to become more sustainable.

<p>Today, automated software testing has been implemented successfully in many systems, however there does still exist relatively unexplored areas as how automated testing can be implemented in a real-time embedded system. This problem has been the foundation for the work in this master thesis, to investigate the possibility to implement an automated software testing process for the testing of an embedded real-time system at IVU Traffic Technologies AG in Aachen, Germany.</p><p>The system that has been the test object is the on board system i.box.</p><p>This report contains the result of a literature study in order to present the foundation behind the solution to the problem of the thesis. Questions answered in the study are: when to automate, how to automate and which traps should one avoid when implementing an automated software testing process in an embedded system.</p><p>The process of automating the manual process has contained steps as constructing test cases for automated testing, analysing whether an existing tool should be used or a unique test system needs to be developed. The analysis, based on the requirements on the test system, the literature study and an investigation of available test tools, lead to the development of a new test tool. Due to limited devlopement time and characterstics of the i.box, the new tool was built based on post execution evaluation. The tool was therefore divided into two parts, a part that executed the test and a part that evaluated the result. By implementing an automated test tool it has been proved that it is possible to automate the test process at system test level in the i.box.</p>

Today, automated software testing has been implemented successfully in many systems, however there does still exist relatively unexplored areas as how automated testing can be implemented in a real-time embedded system. This problem has been the foundation for the work in this master thesis, to investigate the possibility to implement an automated software testing process for the testing of an embedded real-time system at IVU Traffic Technologies AG in Aachen, Germany. The system that has been the test object is the on board system i.box. This report contains the result of a literature study in order to present the foundation behind the solution to the problem of the thesis. Questions answered in the study are: when to automate, how to automate and which traps should one avoid when implementing an automated software testing process in an embedded system. The process of automating the manual process has contained steps as constructing test cases for automated testing, analysing whether an existing tool should be used or a unique test system needs to be developed. The analysis, based on the requirements on the test system, the literature study and an investigation of available test tools, lead to the development of a new test tool. Due to limited devlopement time and characterstics of the i.box, the new tool was built based on post execution evaluation. The tool was therefore divided into two parts, a part that executed the test and a part that evaluated the result. By implementing an automated test tool it has been proved that it is possible to automate the test process at system test level in the i.box.

This research project aimed at evaluating four internationally accepted leachate extraction tests to determine their applicability on sewage sludge samples. Furthermore, the present analytical method to determine the leachable fraction of sludge for compliance to South African sludge legislation was evaluated. Leaching tests are done on sludge samples to determine element mobility. This is important since land application of sewage sludge is an accepted and regulated sludge management practice. A literature survey was done to evaluate the mobility over time of metals originating from sludge-amended soils. Mobility is initially due to the organic content of the soil and after organic matter decomposition, it is dependant on the inorganic content. Mobile metals in sludge-amended soil can cause potential environmental risks like groundwater contamination and metal accumulation in soil. Metal accumulation can further lead to increased plant uptake of metals. To determine the partitioning or fractionation of metals found in sludge-amended soil, selective sequential extractions and single extractions can be used. Since South African sludge legislation specifies a single extraction procedure, four were selected for comparative studies. The selected procedures were the USA Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) the Australian Standard Bottle leaching Test (AS 4439.3) the Nederlands Normalisatie-Insitiuut availability test (NEN 7341) and the Deutches Institut für Normung water leachability test (DIN 38 414-S4). A variation of the TCLP is specified for use in South Africa. Three sewage sludge sample lots were collected. The first consisted of 24 sub-samples that were collected from 24 different wastewater treatment works on the East Rand. Both leachable (TCLP) and total (aqua regia) extraction was done on these samples for Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Zn, Se, B and Fe. A relationship between the leachable and total extractions was found for Co and Pb but could not be tested by literature values due to a variation in the sample preparation. The TCLP leachates were also analysed by Atomic Absorption and Inductively Coupled Plasma techniques to compare the applicability of the two. It was found that both techniques are acceptable for leachate analysis. The second sample lot collected from a single wastewater treatment plant was used to determine the leachable effect of the difference between the South African adapted TCLP and the USA EPA procedure as well as the NEN procedure. The EPA specifies all samples be extracted on an “as is” basis while the South African adaptation specifies dry samples. It was found that no element was comparative between dry and wet sample for both extraction procedures. It was observed that wet extractions yield generally higher values than dry extractions. A third sample lot was collected two months after the second sample lot at the same wastewater treatment works. It was used to compare the four extraction procedures. From this it was found that the DIN yielded the highest results for the specified elements. This procedure could not be recommended since the experimental difficulties and the duration of the test make it an unsuitable regulatory compliance tests protocol. / Dissertation (MSc (Environmental Technology))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

No description available.

A uniplanar balun that transforms unbalanced coplanar waveguide (CPW) to balanced coplanar strip line (CPS) is characterised through simulation and measurement. By illustrating the effect of many of the critical design parameters, the operation of this balun is discussed and a set of design criteria is defined. The parameter study discusses the size and shape of the radial open, the type and length of the CPW taper and the thickness and type of the bond wires. Newly developed etched bond wires are implemented to provide better manufacturing repeatability and reliability. A complete balun testing procedure is developed and described, consisting of three separate tests. The balun is tested in the normal back-to-back configuration, as a terminated single balun, and the magnitude and phase imbalance is also determined by using a three-port test circuit connected to the balun. The advantages of implementing this full test procedure, and thus fully characterising the balun under test, are emphasised throughout. Results obtained by using this procedure show that the basic balun works well over the full operating band, except for the phase imbalance, which is usable but not optimal. A simple technique to correct the phase imbalance of the balun is introduced, and validated through measurements of the balun connected to the three-port test circuit. As a final validation the balun is connected as feed for an etched dipole antenna for which good impedance matching and pattern results are shown. AFRIKAANS : ’n Enkelvlak balon (BALans-na-ONbalans) wat van ongebalanseerde enkelvlak golfgeleier (CPW) na gebalanseerde enkelvlak strooklyn (CPS) transformeer, word gekarakteriseer deur simulasie en metings. Deur die effek van baie van die kritiese ontwerpsparameters te demonstreer, word die werking van die balon bespreek en ’n stel ontwerpskriteria opgestel. Die parameter studie bespreek die radiale ope struktuur se vorm en grote, die tipe en lengte van die CPW transformator and die dikte en tipe van die konneksie drade. Nuut ontwikkelde geëtste konneksie drade word geïmplementeer om beter vervaardigingsherhaalbaarheid en betroubaarheid te verseker. ’n Volledige balon toetsprosedure word ontwikkel en beskryf en bestaan uit drie aparte toetse. Die balon word getoets in die normale rug-aan-rug konfigurasie, as ’n enkel getermineerde balon en die grote asook fase van die wanbalans word bepaal deur die gebruik van ’n drie-poort toetsbaan wat aan die balon gekoppel word. Die voordele verbonde daaraan om hierdie volledige toetsprosedure toe te pas, en daardeur die balon volledig te karakteriseer, word deurlopend beklemtoon. Die resultate wat hierdie prosedure oplewer wys dat die basiese balon goed werk oor die volledige frekwensieband, behalwe vir die fase-wanbalans parameter, wat bruikbaar, maar nie ideaal is nie. ’n Eenvoudige tegniek om die fase-wanbalans van die balon te korrigeer word bekend gestel en getoets deur die drie-poort toetsbaan weer te gebruik. As ’n finale validasie word die balon aan ’n geëtste dipool gekoppel word, waarvan goeie impedansie aanpassings en patrone gewys word. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted