<p> With the increasing demand for data rate and transmission distance, the trend in fiber-optic communications is to build an ultra-high, long-haul transmission system. One of the challenges in this kind of systems comes from the fiber dispersion and dispersion slope. For the wide-band wavelength-division multiplexing (WDM) system or ultra-high bit rate optical time-division multiplexing (OTDM) system, the dispersion slope could be a serious problem to impair the system performance.</p> <p> Many studies have shown that the dispersion and dispersion slope affect the long-haul fiber transmission dramatically, especially for the high-capacity systems. Most of them recommend to totally compensate the dispersion and the dispersion slope simultaneously. And a lot of compensating techniques are proposed. However, it is not easy to realize the simultaneous compensation for the dispersion and dispersion slope in the practical systems. Therefore, the necessity of compensating the dispersion slope in wide-bandwidth systems should be verified.</p> <p> We focus on the study of ultra-high bit rate (160-Gb/s) single-channel fiber-optic transmission. The results show that the dispersion slope is not necessary for the dispersion-managed system when the optimal launch parameters are given. Then we present how to find out the optimum in fiber-optic systems and a novel optimizing technology, space mapping technology (SM) is introduced, which has been successfully applied to the electromagnetic area. An application of SM in optical systems is implemented. By using this smart optimization technique, lots of computational efforts for evaluating the fine model in optimization process are saved.</p> / Thesis / Master of Applied Science (MASc)

Air quality permits are required for the construction of all new surface mining operations. An air quality permit requires a surface mining operation to estimate the type and amount of pollutants the facility will produce. During surface mining the most common pollutant is particulate matter having an aerodynamic diameter less than 10 microns (PM10). The Industrial Source Complex (ISC3) model, created by the United States Environmental Protection Agency (U.S. EPA), is a model used for predicting dispersion of pollutants from industrial facilities, including surface mines and quarries. The use of this model is required when applying for a surface mining permit. However, the U.S. EPA and mining companies have repeatedly demonstrated that this model over-predicts the amount of PM10 dispersed by surface mining facilities, resulting in denied air quality permits. Past research has shown that haul trucks create the majority (80-90%) of PM10 emissions from surface mining operations. Therefore, this research concentrated on improving the ISC3 model by focusing on modeling PM10 emissions from mobile sources, specifically haul trucks at surface mining operations. Research into the ISC3 model showed that its original intended use was for facilities that emit pollutants via smoke stacks. The method used to improve the ISC3 model consisted of applying the dispersion equation used by the ISC3 model in a manner more representative of a moving haul truck. A new model called the Dynamic Component Program was developed to allow modeling of dust dispersion from haul trucks. To validate the Dynamic Component Program, field experiments were designed and conducted. These experiments measured PM10 from haul trucks at two different surface mining operations. The resulting analysis of the Dynamic Component Program, ISC3 model, and the actual field study results showed that the Dynamic Component Program was a 77% improvement over the ISC3 model overall. / Ph. D.

Mine haul road maintenance is traditionally done at scheduled intervals or after regular inspection. Both these methods can lead to unwarranted expenditure, either through over-maintaining the road, or failure to recognise significant deterioration, resulting in an increase in vehicle operating costs. Predictive maintenance management models for unpaved roads have been developed in recent years. These methods work well in a trivial environment where variables such as traffic volume can be predicted. However, many mining systems are too complex for such models to be effective. This work investigates the possibility of using haul truck response to aid haul road maintenance management. The approach adopted for the study was twofold: Firstly, can truck response data be used to recognise specific road defects, in terms of location, type and size? This is important since different defect types require different road maintenance strategies. Secondly, can road roughness be measured on a qualitative basis? With the emphasis on road defect reconstruction, a mathematical modelling approach was adopted. The truck was characterised in terms of its suspension and tyre properties. Dynamic truck response data was acquired during field measurements in which the vehicle was driven over defects of known dimensions. With these data sets available, mathematical modelling and simulation was possible. Quarter vehicle and seven degree of freedom vehicle models played a vital role in this work by laying a foundation in the use of haul truck response for the purpose of road defect reconstruction. A modelling methodology that is based on dynamic equilibrium of an independent front unsprung mass of the truck is proposed in which the vertical dynamic tyre force and eventually the road geometry is calculated. It is shown that defects can be reconstructed from measured truck response data with an accuracy sufficient to fulfil the requirements of defect recognition for road maintenance management purposes. Secondly, a preliminary investigation into the qualitative assessment of road condition via truck response measurements was conducted. The inherent response properties of the truck pertaining to road roughness measurement were studied and some correlation between measured suspension motion and road roughness measured with a high speed profilometer was found. / Dissertation (MEng (Mechanical))--University of Pretoria, 2005. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

O preço atual do minério de ferro obrigou as empresas a reduzirem os custos operacionais na fase mina. O carregamento e transporte de materiais com utilização de escavadeiras e caminhões grande porte representam grande parcela do custo total, particularmente com pneus, diesel, manutenção e mão de obra. Metas de movimentação anual são divididas durante os meses e as condições climáticas podem influenciar na produtividade e desempenho dos equipamentos. O banco de dados da movimentação mensal está condicionado com a capacidade de cada caminhão. Cada frota possui o payload característico e este representa a capacidade de transporte, sendo o valor da massa transportada o único parâmetro extraído em cada ciclo, sem considerar o posicionamento do material sobre a caçamba dos equipamentos. Forças de cisalhamento e torção são aplicadas constantemente no chassi e pneus dos caminhões e, quando as cargas estão descentralizadas, potencializam estes eventos. O transporte de cargas descentralizadas agride os pneus diminuindo a vida útil causando danos como deslocamento da banda de rodagem e separação do flanco. Este trabalho teve como objetivo diminuir as ocorrências de cargas descentralizadas e os custos operacionais. Para incrementar o posicionamento do material sobre as caçambas, a telemetria foi a ferramenta utilizada. Análises de pressões de suspensões indicam o posicionamento das cargas e através desses valores foi criado um banco de dados. Este banco de dados pode indicar qual operador de carga precisa de reciclagem, contribuindo para a redução de cargas descentralizadas e custos, uma vez que cargas deste perfil sucateiam precocemente pneus e suspensões. O estudo foi realizado em Itabira, em uma mina de minério de ferro a céu aberto. A metodologia comprovou ser capaz diminuir as ocorrências de cargas descentralizadas assim como aumentar a vida útil de pneus. Uma possível economia foi apresentada para ano de 2014, período em que a média das horas trabalhadas de pneus ficou abaixo da meta aumentando os custos fase mina. / The actual iron ore price forces the companies to reduce costs in all production steps of the mining operation. Loading and hauling materials using shovel-truck system represents the highest mining costs, particularly tires, diesel, maintenance and workforce. Annual goals of materials movement are split by months were weather conditions can affect productivity and performance of the fleet. The data file of the monthly material movement is based on the scale of each truck. Every fleet has a payload and it represents the capacity of hauling, being the value of loading a unique input extracted in each duty cycle, without taking into account the position of the material over the truck’s dump. Shear forces and torsion are applied all time at the frames trucks and, when the truckloads are unbalanced, increases the forces over the frame and tires. Transport unbalanced truckloads into long distances attack the tires and decrease its end of life, causing damages like displacement of tread and flank separation. The objective of this study is to propose a methodology to decrease unbalanced truck loads reducing the mining costs. In this mission of incorporating a material position on the truck´s dump, the telemetry was taking into consideration. The analysis of the suspension pressures data values shows the truckloads positions and with this data was created a databank. This databank indicates that the operators need truck load training to reduce unbalanced loads and truck costs in the mining operation, since unbalanced loads leads to early tires and suspensions scrap. The case study was carried out at Itabira Iron Ore Mine Complex, Brazil. This methodology was able to reduce the number of unbalanced truck loads as well as the tires life was increased. An economic saving estimate is presented based on 2014 scrapped tires data bank, in this year the tires life cycle was underneath, burdening operational costs.

Nos últimos anos, tem-se presenciado um contínuo aumento na demanda por transporte de carga ferroviário no Brasil, o que tem se refletido em maior volume de projetos para expansão ou revitalização da malha existente no país. Diante deste quadro atual, torna-se essencial que o profissional envolvido com a elaboração de projetos da via permanente tenha em mãos informações atualizadas a respeito da variedade de componentes da grade ferroviária existente no mercado, a fim de que os projetos atendam plenamente às necessidades do cliente. Assim sendo, o presente trabalho tem como principal objetivo pesquisar e analisar os tipos de componentes existentes no mercado usados na composição da grade ferroviária (trilhos, dormentes e fixações), com foco principal naqueles que podem ser aplicados às ferrovias de transporte de carga. Primeiramente, a partir de pesquisa em material bibliográfico nacional e internacional, serão descritos os principais aspectos técnicos que devem ser considerados no processo de avaliação destes componentes, tendo como base os parâmetros de projeto da via estabelecidos previamente de acordo com as exigências da operação de carga, tais como: carga por eixo, velocidade de operação, rampa máxima, etc. Em seguida, serão apresentados os tipos de trilhos, dormentes (madeira, concreto monobloco e bi-bloco, aço e plástico) e fixações (rígidas e elásticas) existentes atualmente no mercado e suas características de desempenho e condições de uso estabelecidas pelos respectivos fabricantes. Os dados obtidos nas duas etapas descritas anteriormente serão analisados e confrontados, de forma que seja possível explicitar as relações de interdependência que existem entre os diferentes tipos de componentes. Ao final do trabalho, será apresentado um modelo de fluxograma que reúne os dados de entrada para o projeto da ferrovia de transporte de carga, as diretrizes técnicas que devem ser atendidas em seu projeto e, por fim, os tipos de componentes da grade ferroviária que podem ser empregados de acordo com o caso estudado. Com isso, espera-se que o produto final gerado possa ser uma ferramenta útil na etapa de concepção de novos projetos ferroviários, visto que apresentará de maneira clara e objetiva um conjunto de informações bastante abrangente e atualizado a respeito dos critérios técnicos e das opções de componentes disponíveis no mercado, fornecendo uma orientação inicial consistente ao profissional envolvido sobre os materiais que podem ser aplicados à via em estudo. / Over the last years, a continuous increase on demand for railroad heavy haul transport has been witnessed in Brazil, reflecting in bigger volume of projects for expansion or improvement of the existing lines in the country. With this current situation, it becomes essential that the professional involved with the elaboration of projects of the permanent way should have information brought up to date regarding the variety of components of the existing railroad materials in the market, so that the projects take care of fully to the necessities of the customer. Thus being, the present work has as main objective to search and to analyze the types of existing components in the market used in the composition of the railroad superstructure (rails, ties and fastenings), with main focus in that which can be applied to the heavy haul railways. First, from research in national and international bibliographical material, the main aspects related to the performance that must be considered in the process of evaluation of these components will be describes, having as base the design parameters of the way established previously in accordance with the requirements of the load operation, such as: position for axle, speed of operation, maximum slope, and others. After that, the types of rails, ties (wood ties, monoblock and bi-block concrete ties, steel ties and plastic ties) and fastenings (rigid and elastic) currently available in the market and its characteristics of performance and conditions of use will be presented, according to the information provided by the its respective manufacturers. All the reports showed in the two previous described stages will be analyzed and compared, so that is possible to highlight the interdependence relations that exist between the different types of components. At the end of the work, a flowchart model which gathers the input data about the heavy haul railroad, the performance guidelines that should be followed and the types of components of the railroad superstructure that can be used in accordance to the studied case, will be presented. With that, it is expected that the produced flowchart could be a useful tool in the stage of design of a new railroad, once it will present in a clear and objective way an embracing and up-to-date set of information regarding the performance criteria and the options of components available in the market, supplying a consistent initial orientation to the designer about the materials that could be applied to the railway.

Long haulage of heavy-duty trucks weighing over 15-ton stands for nearly 50% of the fuelconsumption among trucks, making them the most fuel consuming category. This indicatesthe potential benefits in improving the fuel efficiency for said category. Hybridization is onepossible solution.Hybrid vehicles are vehicles with two or more power sources in the powertrain. Differentpowertrain configurations, hybridization levels and hybrid concepts are best suitedfor different applications. With prices for fossil fuels constantly rising hybridization is animportant technology to improve fuel efficiency.Different variations of configurations and concepts enables many choices when decidingon a hybrid driveline. A simulation tool for efficiently comparing various hybrid drivelineswould be a great asset when deciding on a configuration for a certain vehicle application. Forthis thesis the application in focus is the previously mentioned category, a heavy duty longhauler weighing 36-ton.The modeling approach used for the simulation tool is called quasistatic modeling or"backward modeling". This name comes from, based on a chosen drive cycle, the resistingforces which act on the vehicle can statically be calculated at each step from the velocityprofile. The required power to drive along the drive cycle can then be calculated backwardswithin the powertrain resulting in a fuel consumption for the combustion engine. For thisthe free QSS-toolbox for Matlab Simulink has been used as a base and modified when needed.The configuration chosen to be implemented is a parallel electric hybrid and was chosenfor its good characteristics for the type of driving highways provide. For this configurationtwo types of controllers are used, one being an Equivalent Consumption Minimization Strategycontroller and the other a simple, rule based heuristic controller.The results for both controllers show small benefits with hybridization of the longhauler compared with the conventional which in the long run would make bigger differencebecause of the large consumption in whole. A sensitivity analysis was also done showingthat improving conventional vehicle parameters can be as beneficial as hybridization.

Methods for estimating productivity and costs, and dependent equipment selection process, have needed to be increasingly reliable. Estimated productivity and costs must be as accurate as possible in reflecting actual productivity and costs experienced by mining operations to accommodate the long-term trend for diminishing commodity prices, For loading and hauling equipment operating in open pit mines, some of the interrelated estimating criteria have been investigated for better understanding; and, consequently, more reliable estimates of production and costs, also more effective equipment selection process. Analysis recognizes many of the interrelated criteria as random variables that can most effectively be reviewed, analyzed and compared in terms of statistical mathematical parameters. Emphasized throughout is the need for management of the cyclical loading and hauling system using conventional shovels/excavators/loaders and mining trucks to sustain an acceptable “rhythm” for best practice productivity and most-competitive unit-production costs. Outcomes of the research include an understanding that variability of attributes needs to be contained within acceptable limits. Attributes investigated include truck payloads, bucket loads, loader cycle time, truck loading time and truck cycle time. Selection of “ultra-class” mining trucks (≥ 290 -tonne payload) and suitable loading equipment is for specialist mining applications only. Where local operating environment and cost factors favourably supplement diminishing cost-benefits of truck scale, ultra-class trucks may be justified. Bigger is not always better – only where bigger can be shown to be better by reasons in addition to the modest cost benefits of ultra-class equipment. Truck over-loading may, to a moderate degree, increase productivity, but only at increased unit cost. / From a unit-cost perspective it is better to under-load than overload mining trucks. Where unit production cost is more important than absolute productivity, under-trucking is favoured compared with over-trucking loading equipment. Bunching of mining trucks manifests as a queuing effect – a loss of effective truck hours. To offset the queuing effect, required productivity needs to be adjusted to anticipate “bunching inefficiency”. The “basic number of trucks” delivered by deterministic estimating must provide for bunching inefficiency before application of simulation applications or stochastic analysis is used to determine the necessary number of trucks in the fleet. In difficult digging conditions it is more important to retain truck operating rhythm than to focus on achieving target payload by indiscriminately adding loader passes. Where trucks are waiting to load, operational tempo should be restored by sacrificing one or more passes. Trucks should preferably be loaded by not more than the nominal (modal) number plus one pass. The research has: • Identified and investigated attributes that affect the dispersion of truck payloads, bucket loads, bucket-cycle time, loading time and truck-cycle time. • The outcomes of the research indicate a need to correlate drilling and blasting quality control and truck payload dispersion. Further research can be expected to determine the interrelationship between accuracy of drilling and blasting attributes including accuracy of hole location and direction. • Preliminary investigations indicate a relationship between drill-and-blast attributes through blasting quality control to bucket design, dimensions and shape; also discharge characteristics that affect bucket cycle time that needs further research.

Tracking studies conducted by the Australian Tourist Commission (ATC) over the last decade have revealed that Australia has a high ranking as a desired destination among US residents. However prior to the peaked effect of the Olympics, this desire had not translated into increasing numbers of visitor arrivals from the US. As travel to Australia from the US is time consuming and involves extremes of physical distance, it would be to Australia's advantage to understand better the dimensions and ramifications of long haul travel with regard to destination choice. This thesis has two objectives: to assess the extent to which a destination being a long haul from its target market affects the choice of this destination; and to consider the marketing implications of the above with a focus on the selection of Australia, as compared to competitive destinations, by the US holiday market. Data were collected from two samples: the West Coast of the US and the East Coast of Australia. The instrument for the US sample collected information on the respondents' choice set structure, attribute importance in selecting a long haul destination, perceptions of the long haul destinations of Australia and Italy, and sociodemographics. The instrument for the Australian sample collected information on the respondents' choice set structure, attribute importance for both long haul and short haul destination selection, perceptions of the long haul destination of the US and the short haul destination of New Zealand, and sociodemographics. This data were then used to test nine hypotheses designed to give insight into the research objectives. The results indicate that tourists place differing degrees of importance on attributes of a long haul destination as compared to a short haul destination for a vacation. It also demonstrates that tourists' perceptions of the distance to destinations are often highly inaccurate and that this inaccuracy is related neither to actual distance nor choice set placement. The cognitive distance is however directly related to perceptions of cost of travelling to the destination. A conundrum was also established in that the distance to Australia was overestimated and related positively with the choice of the destination. Yet at the same time the overestimation led to increasing perceptions of cost, travel time and risk, which indirectly had a negative impact on the choice of the destination. This far-off allure was not evident for the equidistant competitor, Italy, where the cognitive distance was underestimated. It was also found US respondent's place differing importance on the attributes they seek in a long haul destination as compared to the Australian respondents. Notably, the US market places a significantly higher importance on distance, even though their estimation of the distance between Australia and the US did not differ from the Australian estimate. Marketing implications for Australia as a long haul destination were then considered with an emphasis on redefining vacation distances in tourists' minds without relinquishing the far-off allure. The relationship between cognitive distance and perceptions of cost and time in comparison to competitors were driving the need for redefining distance. Emphasis was placed on delivering information to tourists during their decision process when their involvement and information processing was highest. Direction was also given for future research that would be useful for travel marketers in gaining additional insight into their long haul target markets.

As an information intensive industry and as one of the most progressive industries in information technology adoption, travel and tourism provides an ideal context in which to investigate how new technologies such as interactive television challenge our understanding of media and media use. This research looks at how interactive television can be used by consumers and how it may be best applied by marketers in international holiday travel. Using the UK international traveller market to Western Australia as case in point, this research had three main research goals: 1) to understand how travellers use information sources with a focus on interactive television; 2) how an individual’s previous interactive media and travel experiences may pre-dispose them to using interactive television; and 3) to better understand why individuals interact and what impact the interaction has on the promotional effort. A travel ad and a travel show segment were used to explore these with impulse (brochure request) and telescopic (destination video) interactive opportunities. The treatments were deployed over a video-on-demand platform in greater London and participants took part in their homes via their televisions and a self administered questionnaire. This research has furthered the use of the multi-dimensional grid in understanding information sources in relationship to one another and updated the landscape with modern information sources such as television, teletext, the Internet and interactive television. Findings from this area of investigation suggest that current interactive television offerings cater better to short-haul destinations and although it currently plays a minor role, interactive television has the potential to significantly contribute to travellers’ long-haul holiday planning process. The finding that individuals understand interactive television through their experience with teletext rather than the Internet and are more likely to use interactive television if they are thorough and experienced planners supports the theory of knowledge transference. However, most importantly, if an individual has a positive experience with interactive television they will interact again in the future. Contributions were also made to a better understanding of the interactive television user and the use of interactive television applications to the travel and tourism industry in particular. Exploration of the differences between the Impulse and Telescopic approaches to interactivity highlighted that while interactivity generally enhances the promotional effort each approach has its own strategic applications.

The research work disclosed in this publication is partially funded by the Strategic Educational Pathways Scholarship Scheme (Malta). The scholarship is part-financed by the European Union – European Social Fund under Programme II – Cohesion Policy 2007-2013. / This dissertation documents a compressor preliminary design study conducted by the author in fulfilment of his MSc thesis requirements. The compressor is intended for a new development engine within the 20Klbf thrust category, planned to be used on a short-haul aircraft, namely the ERJ-190. A market research suggests that there exists a definite opportunity for a commercially profitable engine within this thrust class. Furthermore, the proposed new engine is projected to outperform current production engines on critical issues such as fuel efficiency and operability. By and large, the objectives of this work have been achieved and a compressor design and layout is suggested, which matched or exceeded all the initial requirements. The quality of the results from this study are thought to be of sufficient detail to allow a further, more detailed development study to resolve some subtle pending issues. It is expected that, some compressor stages may have to be altered slightly during detailed design to augment their performance and ease of manufacture and assembly. Throughout this study, the importance of the compressor design figure of merits, pertaining to a short haul engine, has been outlined and their interaction on the design process is well documented. Furthermore, some rather unorthodox objectives such as compressor performance retention and reliability have been discussed. The author approached these subjects in an innovative way due to the limited non-proprietary knowledge available on these issues, especially considering their implications within preliminary design. Furthermore, the author developed and tested a new preliminary turbomachinery design code, named Turbodev, which can be used as an aid in future compressor design endeveours. Turbodev can handle most types of compressor layouts and generates an overall aerodynamic assessment of the turbomachinery performance. In conclusion; this documentation and the associated literature review aim to provide the reader with an overview of the work done and yield a better understanding of the decisions that face any design bureau when developing a new or modified engine component.