Critical comparison of Julius Kruttschnitt Mineral Research Centre (JKMRC) blast fragmentation models

Blast fragmentation can have a significant impact on the profitability of a mine. An optimum run of mine (ROM) size distribution is required to maximise the performance of downstream processes. If this fragmentation size distribution can be modelled and controlled, the operation will have made a significant advancement towards improving its performance. Blast fragmentation modelling is an important step in Mine to Mill™ optimisation. It allows the estimation of blast fragmentation distributions for a number of different rock mass, blast geometry, and explosive parameters. These distributions can then be modelled in downstream mining and milling processes to determine the optimum blast design. When a blast hole is detonated rock breakage occurs in two different stress regions - compressive and tensile. In the-first region, compressive stress waves form a 'crushed zone' directly adjacent to the blast hole. The second region, termed the 'cracked zone', occurs outside the crush one. The widely used Kuz-Ram model does not recognise these two blast regions. In the Kuz-Ram model the mean fragment size from the blast is approximated and is then used to estimate the remaining size distribution. Experience has shown that this model predicts the coarse end reasonably accurately, but it can significantly underestimate the amount of fines generated. As part of the Australian Mineral Industries Research Association (AMIRA) P483A Mine to Mill™ project, the Two-Component Model (TCM) and Crush Zone Model (CZM), developed by the Julius Kruttschnitt Mineral Research Centre (JKMRC), were compared and evaluated to measured ROM fragmentation distributions. An important criteria for this comparison was the variation of model results from measured ROM in the-fine to intermediate section (1-100 mm) of the fragmentation curve. This region of the distribution is important for Mine to Mill™ optimisation. The comparison of modelled and Split ROM fragmentation distributions has been conducted in harder ores (UCS greater than 80 MPa). Further work involves modelling softer ores. The comparisons will be continued with future site surveys to increase confidence in the comparison of the CZM and TCM to Split results. Stochastic fragmentation modelling will then be conducted to take into account variation of input parameters. A window of possible fragmentation distributions can be compared to those obtained by Split . Following this work, an improved fragmentation model will be developed in response to these findings.

A JOINT EXPERIMENTAL ANALYSIS OF INVESTOR BEHAVIOR IN IPO PRICING METHODS

This article jointly examines the differences of laboratory versions of the Dutch clock open auction, a sealed-bid auction to represent book building, and a two-stage sealed bid auction to proxy for the “competitive IPO”, a recent innovation used in a few European equity initial public offerings. We investigate pricing, seller allocation, and buyer welfare allocation efficiency and conclude that the book building emulation seems to be as price efficient as the Dutch auction, even after investor learning, whereas the competitive IPO is not price efficient, regardless of learning. The competitive IPO is the most seller allocative efficient method because it maximizes offer proceeds. The Dutch auction emerges as the most buyer welfare allocative efficient method. Underwriters are probably seeking pricing efficiency rather than seller or buyer welfare allocative efficiency and their discretionary pricing and allocation must be important since book building is prominent worldwide.

A questão do género em Moçambique: contributo para uma análise da sua problemática

RESUMO:O desenvolvimento entendido como um processo político, económico e social, visando uma melhoria constante do bem-estar de toda a população, requer a alocação e utilização de recursos para benefício social e económico da sociedade. Porém, em Moçambique, neste processo, o crescimento e progressão dos grupos sociais ainda é desigual, ocorrendo uma certa marginalização e menor participação nos processos de tomada de decisão, das mulheres e dos grupos desfavorecidos. O presente estudo, subordinado ao tema: “A Questão do Género em Moçambique: Contributo para uma análise da sua problemática”, procurou compreender a importância e o contributo das mulheres moçambicanas inseridas em diferentes áreas de desenvolvimento e o seu empoderamento. O estudo foi centrado nas diversas formas de luta e de intervenção contra a pobreza e a exclusão social. A metodologia do presente trabalho consistiu numa pesquisa empírica através da observação participante, onde foram feitas entrevistas, utilizando guiões pré-elaborados que permitiram recolher os perfis sociológicos das ONGs que trabalham directamente com as questões de género. Foram entrevistadas mulheres que ocupam lugares-chave nas instituições governamentais e algumas parlamentares. Foi igualmente consultada a documentação oficial bem como os dados estatísticos que abordam questões ligadas ao género. As observações feitas indicam-nos que a mulher em Moçambique busca gradualmente o seu espaço no desenvolvimento da sociedade, não se esgotando a sua participação apenas nos processos decisórios a nível governamental e das ONGs, antes estendendo-se ao associativismo nos mais diversos campos sociais. A mulher moçambicana participa hoje, individualmente ou organizada em grupo, em lutas e reivindicações colectivas, tendo crescido positivamente ao conseguir ultrapassar diversos obstáculos. A título de conclusão recomenda-se a inclusão de profissionais da área social nos programas de desenvolvimento. Seria uma forma de fortalecer os avanços já alcançados. A presença de assistentes sociais nos órgãos públicos e noutros sectores mais sensíveis, iria por certo permitir reduzir as preocupações dos que buscam estes serviços. ABSTRACT: The present study on the subject: “The Question of Gender in Mozambique: Development and Issues”, demand to understand the importance and contribution that non-governmental organizations provides on the effort of Mozambican woman in having in the society the space that on right belongs to her. The development understood as the economic, social, cultural and political process that aimed a continuous improvement of the population welfare, require the allocation and use of resources for social and economic benefit of society. However in many countries, as is the case of Mozambique, this process is the advancement of certain groups accompanied by the marginalization, exclusion and subordination of others, especially women. Despite improvement in education and combating poverty, access to education for women remains an unusual reality and poverty persists to affect much of Mozambican women, thus causing its social exclusion. On the other hand, although the law recognizes gender equality, women are still oppressed and often the only career that is destined is to be married, take care of the field and having children. However, several exceptions have occurred in which women have to take political positions and functions exclusively reserved to men before. Women's organizations and women leaders participating in favour of the defence of other women have been contributing to its success. UFUPISHO:Maendeleo, yanayosikiwa kama utaratibu wa jamii, ambao unalinga hali njema ya mustarehe wa watu wote wa nchi, yanahitaji toleo na utumizi wa vifaa kwa fadhili ya jamii na ya kiuchumi ya watu jamii. Walakini katika Mozambiki, mwendeleo unaotukia utaratibuni huu hauko sawa. Funzo hili la kuhusu jambo: “ Swali la jinsi ya kuwa kiume au kike Mozambiki: Maendeleo na Tatizo “, lilitafuta kufahamu muhimu na msaada wa wanawake wa Mozambiki katika maeneo mbalimbali ya maendeleo na ongezo la uwezo wao. Funzo lilifanywa juu ya namna nyingi za mapigano na uamuzi kwa kupingana na umaskini na ondoleo katika jamii. Taratibu ya funzo hili ilikuwa uchunguzi jarabati katika onyo la kushirika,ambamo yalifanywa mahojiano, yakitumia maongozi yaliyofanywa mbele ambayo yaliruhusu kujua tabia za elimujamii za “ONGs” ambazo zinafanya kazi juu ya maswali ya jinsi ya kuwa kiume au kike. Walihojiwa wanawake ambao wanamiliki kazi muhimu katika mashirika ya serikali na wanawake wa bunge. Zilichunguwa pia hati rasmi na takwimu zinazohusu maswali ya jinsi ya kuwa kiume au kike. Maonyo yaliyofanywa yanatuonyesha ya kwamba mwanamke katika Mozambika anatafuta kidogo kidogo nafasi yake maendeleoni ya watu jamii, asipojichosha tu kwa kushirika katika taratibu za kubezwa za serikali za “ONGs” na ushirikiano, ukijitanda kwa maeneo ya jamii makubwa zaidi. Mwanamke wa Mozambiki anashirika peke au kwa kundi, akiunganika mapiganoni na madaini ya pamoja, akigua na akiweza kupita vizuizi vingi. Inashauriwa kwamba kama namna ya kuimarisha maendeleo na kwa sababu mwanamke yuko katika sehemu nyingi za jamii, anaingia ndani ya sekta mbalimbali za ufundi kama kwa mfano msaidizi wa jamii. Kuwapo kwa msaidizi wa jamii katika mashirika ya umma na katika sekta nyingine mbalimbali kutaruhusu kumaliza shughuliko ya wale ambao wanatafuta kazi hizi.

Multi-stage evolution of a sub-aerial volcanic ridge over the last 1.3 Myr: S. Jorge Island, Azores Triple Junction

New K/Ar dating and geochemical analyses have been carried out on the WNW-ESE elongated oceanic island of S. Jorge to reconstruct the volcanic evolution of a linear ridge developed close to the Azores triple junction. We show that S. Jorge sub-aerial construction encompasses the last 1.3 Myr, a time interval far much longer than previously reported. The early development of the ridge involved a sub-aerial building phase exposed in the southeast end of the island and now constrained between 1.32 +/- 0.02 and 1.21 +/- 0.02 Ma. Basic lavas from this older stage are alkaline and enriched in incompatible elements, reflecting partial melting of an enriched mantle source. At least three differentiation cycles from alkaline basalts to mugearites are documented within this stage. The successive episodes of magma rising, storage and evolution suggest an intermittent reopening of the magma feeding system, possibly due to recurrent tensional or trans-tensional tectonic events. Present data show a gap in sub-aerial volcanism before a second main ongoing building phase starting at about 750 ka. Sub-aerial construction of the S. Jorge ridge migrated progressively towards the west, but involved several overlapping volcanic episodes constrained along the main WNW-ESE structural axis of the island. Malic magmas erupted during the second phase have been also generated by partial melting of an enriched mantle source. Trace element data suggest, however, variable and lower degrees of partial melting of a shallower mantle domain, which is interpreted as an increasing control of lithospheric deformation on the genesis and extraction of primitive melts during the last 750 kyr. The multi-stage development of the S. Jorge volcanic ridge over the last 1.3 Myr has most likely been greatly influenced by regional tectonics, controlled by deformation along the diffuse boundary between the Nubian and the Eurasian plates, and the increasing effect of sea-floor spreading at the Mid-Atlantic Ridge.

An heuristic approach for optimal location of gas supply units in transportation system

The best places to locate the Gas Supply Units (GSUs) on a natural gas systems and their optimal allocation to loads are the key factors to organize an efficient upstream gas infrastructure. The number of GSUs and their optimal location in a gas network is a decision problem that can be formulated as a linear programming problem. Our emphasis is on the formulation and use of a suitable location model, reflecting real-world operations and constraints of a natural gas system. This paper presents a heuristic model, based on lagrangean approach, developed for finding the optimal GSUs location on a natural gas network, minimizing expenses and maximizing throughput and security of supply.The location model is applied to the Iberian high pressure natural gas network, a system modelised with 65 demand nodes. These nodes are linked by physical and virtual pipelines – road trucks with gas in liquefied form. The location model result shows the best places to locate, with the optimal demand allocation and the most economical gas transport mode: by pipeline or by road truck.

Transmission price simulator in a liberalized electricity market

This paper presents a software tool (SIM_CMTP) that solves congestion situations and evaluates the taxes to be paid to the transmission system by market agents. SIM_CMTP provides users with a set of alternative methods for cost allocation and enables the definition of specific rules, according to each market and/or situation needs. With these characteristics, SIM_CMTP can be used as an operation aid for Transmission System Operator (TSO) or Independent System Operator (ISO). Due to its openness, it can also be used as a decision-making support tool for evaluating different options of market rules in competitive market environment, guarantying the economic sustainability of the transmission system.

Dissolução redutiva de minério de ferro por Acidithiobacillus ferrooxidans para a recuperação de metais de interesse econômico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O Sistema custeio baseado em atividades e a melhor afetação dos recursos

Orientada pela Prof. Doutora Cláudia Lopes

Avaliação da qualidade do ar interior e estudos CFD em espaços do ISEP

Mestrado em Engenharia Química. Ramo Tecnologias de Protecção Ambiental.

Valorização de subprodutos da vinha e do vinho: impacto do tempo e métodos de preservação nas suas características

Os polifenóis constituem um grupo biologicamente relevante de compostos naturais, que têm gerado um crescente interesse por parte dos consumidores e das indústrias alimentar, farmacêutica e de cosméticos. Os compostos fenólicos exibem uma vasta gama de propriedades fisiológicas, tais como anti-alérgica, anti-aterogénica, anti-inflamatória, anti-microbiana, antioxidante, anti-trombótica, possuindo efeitos cardio-protetores e vasodilatadores. Por conseguinte, o interesse na obtenção deste compostos ativos de uma forma fácil, barata e rápida tem vindo a aumentar. Uma das fontes de polifenóis são os subprodutos agrícolas, tais como os produtos derivados do vinho e/ou processamento de uvas. As folhas, os caules e os resíduos obtidos durante o processo de produção do vinho têm sido subutilizados, apesar de representarem uma boa fonte de compostos antioxidantes e bioativos. Portugal é um dos mais importantes países produtores de vinho, onde todos os anos são geradas várias toneladas de subprodutos associados a esta indústria. A extração, caracterização, quantificação e avaliação da atividade antioxidante de compostos bioativos extraídos destes subprodutos são, pois, tarefas importantes a fim de avaliar o potencial de utilização destes produtos como novas fontes de compostos antioxidantes. O objetivo deste trabalho foi quantificar e avaliar os teores de polifenóis de extratos preparados a partir de folhas e caules de videira, e bagaço, engaço e grainha de uva. Os parâmetros experimentais da extração foram otimizados, incluindo a proporção de solvente de extração (água/etanol), a temperatura e o tempo de extração. A quantificação dos polifenóis (como fenóis totais e flavonoides) foi efetuada por espetrofotometria de UV/Vis. Verificou-se que a melhor razão de solventes extratores foi de 50/50 (v/v) em água/etanol para todos os subprodutos estudados. No caso dos subprodutos folhas e caules, as condições ideais de extração foram obtidas quando se usou uma temperatura de 40ºC e um tempo de extração de 30 min. Para o bagaço, a temperatura ideal foi de 55ºC durante 5 min. Para o engaço e grainha a utilização de uma temperatura de 40ºC durante 5 min e 30 min, respetivamente, revelou-se o ideal para se obter os compostos. Com este trabalho conclui-se que os subprodutos da vinha e do vinho efetivamente possuem compostos de elevado valor e com capacidade antioxidante.

Robótica móvel: sistema de condução autónoma

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo Automação e Electrónica Industrial

Simultaneous distillation–extraction of high-value volatile compounds from Cistus ladanifer L.

The present paper describes a procedure to isolate volatiles from rock-rose (Cistus ladanifer L.) using simultaneous distillation–extraction (SDE). High-value volatile compounds (HVVC) were selected and the influence of the extraction conditions investigated. The effect of the solvent nature and extraction time on SDE efficiency was studied. The best performance was achieved with pentane in 1 h operation. The extraction efficiencies ranged from 65% to 85% and the repeatability varied between 4% and 6% (as a CV%). The C. ladanifer SDE extracts were analysed by headspace solid phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The HS-SPME sampling conditions such as fiber coating, temperature, ionic strength and exposure time were optimized. The best results were achieved with an 85 µm polyacrylate fiber for a 60 min headspace extraction at 40ºC with 20% (w/v) of NaCl. For optimized conditions the recovery was in average higher than 90% for all compounds and the intermediate precision ranged from 4 to 9% (as CV %). The volatiles α-pinene (22.2 mg g−1 of extract), 2,2,6-trimethylcyclohexanone (6.1 mg g−1 of extract), borneol (3.0 mg g−1 of extract) and bornyl acetate (3.9 mg g−1 of extract) were identified in the SDE extracts obtained from the fresh plant material.

Quantifying the channel quality for interference-aware wireless sensor networks

Reliability of communications is key to expand application domains for sensor networks. SinceWireless Sensor Networks (WSN) operate in the license-free Industrial Scientific and Medical (ISM) bands and hence share the spectrum with other wireless technologies, addressing interference is an important challenge. In order to minimize its effect, nodes can dynamically adapt radio resources provided information about current spectrum usage is available. We present a new channel quality metric, based on availability of the channel over time, which meaningfully quantifies spectrum usage. We discuss the optimum scanning time for capturing the channel condition while maintaining energy-efficiency. Using data collected from a number of Wi-Fi networks operating in a library building, we show that our metric has strong correlation with the Packet Reception Rate (PRR). This suggests that quantifying interference in the channel can help in adapting resources for better reliability. We present a discussion of the usage of our metric for various resource allocation and adaptation strategies.

Liderança transformacional/transacional: que impacto no cinismo organizacional?

Dissertação apresentada à Escola Superior de Comunicação Social como parte dos requisitos para obtenção de grau de mestre em Gestão Estratégica das Relações Públicas.

Coding mode decision algorithm for binary descriptor coding

In visual sensor networks, local feature descriptors can be computed at the sensing nodes, which work collaboratively on the data obtained to make an efficient visual analysis. In fact, with a minimal amount of computational effort, the detection and extraction of local features, such as binary descriptors, can provide a reliable and compact image representation. In this paper, it is proposed to extract and code binary descriptors to meet the energy and bandwidth constraints at each sensing node. The major contribution is a binary descriptor coding technique that exploits the correlation using two different coding modes: Intra, which exploits the correlation between the elements that compose a descriptor; and Inter, which exploits the correlation between descriptors of the same image. The experimental results show bitrate savings up to 35% without any impact in the performance efficiency of the image retrieval task. © 2014 EURASIP.