978 resultados para Tin mines and mining


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Scientific community' is common currency in the study of science, largely due to Kuhn's use of the term in his highly influential book The Structure of Scientific Revolutions. As this article explains, however, 'scientific community' was not of Kuhn's coining. It was hinted at by Peirce, and expressly designated by Royce. On a few occasions Fleck affirmed a scientific community, while Polanyi studied it in some detail. The article concludes by comparing these thinkers' 'communitarian' interpretations of science.

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Damping behaviours of the open cell microcellular pure Al foams fabricated by sintering and dissolution process with the relative density of 0·31-0·42 and the pore size of 112-325 μm were investigated. The damping characterisation was conducted on a multifunction internal friction apparatus. The internal friction (IF) was measured at frequencies of 1·0, 3·0 and 6·0 Hz over the temperature range of 298-725 K. The measured IF shows that the open cell pure Al foam has a damping capacity that is enhanced in comparison with pure Al. At a lower temperature (∼400 K), the IF of the open cell pure Al foams increases with decreasing relative density, with decreasing pore size and with increasing frequency. The IF peak was found at the temperature range of 433-593 K in the IF curves. It is clear that the IF peak is relaxational type and the activation energy associated with the IF peak is about 1·60 ± 0·02 eV. Defect effects can be used to interpret the damping mechanisms.

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The microstructure evolution during hot deformation of a 23Cr-5Ni-3Mo duplex stainless steel was investigated in torsion. The presence of a soft δ ferrite phase in the vicinity of austenite caused strain partitioning, with accommodation of more strain in the δ ferrite. Furthermore, owing to the limited number of austenite/austenite grain boundaries, the kinetics of dynamic recrystallisation (DRX) in austenite was very slow. The first DRX grains in the austenite phase formed at a strain beyond the peak and proceeded to <15% of the microstructure at the rupture strain of the sample. On the other hand, the microstructure evolution in δ ferrite started by formation of low angle grain boundaries at low strains and the density of these boundaries increased with increasing strain. There was clear evidence of continuous dynamic recrystallisation in this phase at strains beyond the peak. However, in the δ ferrite phase at high strains, most grains consisted of δ/δ and δ/γ boundaries.

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The dynamic adjustment of ferrite grains formed during 'dynamic strain induced transformation (DSIT)' is an important feature of this mechanism that has not been addressed previously. A novel experimental method was applied to follow the effect of deformation at different stages on ferrite formed initially through DSIT. It is shown that while the continuous dynamic recrystallisation (CDRX) appears to be an acceptable mechanism for re-refinement of coarser grain size (i.e. dα>2dDSIT), it cannot explain the steady state grain size for finer ferrite grains (i.e. dα<2dDSIT). Other potential mechanisms involved in this phenomenon are examined.

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This paper proposes a conceptual matrix model with algorithms for biological data processing. The required elements for constructing a matrix model are discussed. The representative matrix-based methods and algorithms which have potentials in biological data processing are presented / proposed. Some application cases of the model in biological data processing are studied, which show the applicability of this model in various kinds of biological data processing. This conceptual model established a framework within which biological data processing and mining could be conducted. The model is also heuristic to other applications.

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Transformation of the mineral law system as part of the new political  dispensation in South Africa has long been foreseen. Subsequent to a Green and White Paper, as policy documents, the Department of Minerals and Energy published a Mineral Development Draft 8il12000 for public comment. This eventually culminated in the acceptance by Parliament of the Minerals and Petroleum Resources Development Act 28 of 2002, which came into operation on 1 May 2004. The Act will transform thE! mineral law system and the mining industry in" general. In this article the phaSing-out by the Act of the historical notion of 'mineral right' is examined. It is argue..d that the Act will lead to an exodus of the notion of mineral rights and will replace It with less secure prospecting rights and mining rights which, albeit real in nature, will depend on compliance with provisions of the Act and the exercise of discre.Von by the Minister.

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The Mineral and Petroleum Resources Development Act 28 of 2002 has created new categories of rights to "minerals" that may be granted to applicants by the Minister of Minerals and Energy. In this article the nature of these rights will be examined. The legislature has labelled prospecting rights and mining rights to minerals as limited real rights in the MPRD Act. The remaining rights to minerals are not labelled. Provision is made for registration or recording rights in the revived Mining Titles Registration Act 16 of 1967 (as amended). Registered rights are claimed to constitute a limited real right binding against third parties. Discrepancies and contradictions regarding the nature of rights to minerals are created by the two statutes. It is concluded that only upon clarification of the provisions of the two sister statutes, would the nature of rights to minerals be more evident. The proposed amendment of section 5(1) of the MPRD Act would be in line with property doctrine based upon the common law and is to be welcomed.

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A “neighbour” separated by 6,000 km of Pacific, Mexico is by far New Zealand’s largest trading partner in Latin America and its 15th largest overall. With two-way trade worth NZ$584 million in 2002, many Mexicans grow up on New Zealand milk powder and baby formula. Not only is Mexico’s population of 100 million a huge potential economic partner in its own right, through its network of free trade agreements, Mexico has preferential access to 860 million consumers in 32 countries covering sixty percent of the world’s GDP.

Like New Zealand, Mexico is a “New World” country open to new ideas and innovation. Also like New Zealand, Mexico is known internationally for economic reforms that have created two outward-looking, world-trading, and competitive economies. During the last 50 years, the Mexican economy has shifted away from the once dominant sectors of agriculture and mining toward more industrial activities, especially in the major urban centres of Mexico City, Monterrey, Guadalajara, and other regional centres, where entrepreneurs are concentrated. With this shift, a new class of entrepreneurs arose with the support of the government.

One of those regional centres is the State of Sinaloa, with its capital city, Culiacán. Spearheaded by a visionary government and personified by the Secretary of Economic Development, Heriberto Felix Guerra. Secretary Felix is himself restaurant entrepreneur who owns a growing chain of “concept food” restaurants in the region.

It is no accident that when New Zealand Prime Minister Helen Clark visited Mexican President Vicente Fox Quesada on 15 November 2001, one of the topics of conversation was the fact that very day their two countries had been benchmarked as two of the world’s most entrepreneurial countries in the Global Entrepreneurship Monitor 2001 survey.

More germane, both countries have low-aspiration entrepreneurs who generate low levels of wealth and have low potential for growth. Both are dominated by micro-businesses that do not have high-value-added components and are not investment-ready and pre-qualified for risk capita.

This leads to the question, what can New Zealanders learn from the experience of Mexican entrepreneurship?

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A simple series of test was developed to highlight and compare the difference between the static strain induced transformation (SSIT) and the dynamic strain induced transformation (DSIT) mechanism in grain refinement and also to investigate the origin of the difference between the two mechanisms. The results showed that while the SSIT sets up a two-dimensional impingement among the ferrite grains, it cannot avoid their coarsening (normal growth). However, the DSIT forms a group of grains with a three-dimensional impingement which does not coarsen and maintains their fine size throughout the transformation, thereby, reduces the final average grain size.

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Water management is a matter of global concern. To underpin sound management of water scarcity and quality issues requires high quality, consistent, understandable and credible information. In a world first, accounting and water industry experts in Australia have developed a system of water accounting as an accounting sub-discipline, analogous to financial accounting to guide national and intra-national decision-making. With a conceptual framework and a Preliminary Australian Water Accounting Standard in place, Australia’s approach is being evaluated internationally within the water and mining industries. Its fate as a discipline will depend upon regulatory politics as well as the intellectual and practical rigour of the system and the rate of its adoption. In this paper, we explore the application to water accounting of regulatory theories that have been valuable to gaining an understanding of financial accounting standards development. We predict the international path of the water accounting a sub-discipline of accounting, as an outcome of political forces.

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Based on the behaviour of the superplastic deformation of metallic glasses and Pilling’s model, a diffusion bonding model suitable for metallic glasses is proposed in the present study. In the current model, the diffusion bonding processes consists of two stages: one is the plastic deformation stage and the other is the void shrinkage stage, in which, the atom diffusion and superplastic deformation are responsible for the void shrinkage. Applying this model to the diffusion bonding of a Zr based metallic glass, the predicted bonding time is in good agreement with the experimental result. A map for determining the bonding temperature and time to achieve high quality bonding in a Zr based metallic glass is suggested.

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This paper explores first-day returns on infrastructure entity initial public offerings (IPOs) in Australia from 1996 to 2007. While a good deal has been written on the first-day returns of industrial and mining company IPOs and Real Estate Investment Trust IPOs, first-day returns of infrastructure entity IPOs have yet to be reported in the literature. The study uses ordinary least squares regression analysis to identify factors that might influence the percentage first-day returns theoretically available to investing subscribers and factors that might influence the aggregate amount of money left to subscribers by issuers. The study finds that first-day returns, on average, are not significantly different from zero. There is evidence, however, that suggests higher dividend yields and higher percentage direct costs of capital raising influence these first-day returns. The study also finds that infrastructure entity IPOs that seek to raise more equity capital leave less money on the table for subscribing investors.

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The microstructure-property relationship in conventional high strength low alloy (HSLA) steel was evaluated using data obtained from transmission electron microscopy (TEM) and atom probe tomography (APT). Atom probe tomography allowed the characterisation of fine TiC particles with average radius of 3±1·2 nm that were not observed by TEM. The increase in the yield strength of steel due to the presence of fine precipitates was calculated to be 128 MPa.

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Differential privacy is a strong definition for protecting individual privacy in data releasing and mining. However, it is a rigid definition introducing a large amount of noise to the original dataset, which significantly decreases the quality of data mining results. Recently, how to design a suitable data releasing algorithm for data mining purpose is a hot research area. In this paper, we propose a differential private data releasing algorithm for decision tree construction. The proposed algorithm provides a non-interactive data releasing method through which miner can obtain the complete dataset for data mining purpose. With a given privacy budget, the proposed algorithm generalizes the original dataset, and then specializes it in a differential privacy constrain to construct decision trees. As the designed novel scheme selection operation can fully utilize the allocated privacy budget, the data set released by the proposed algorithm can yield better decision tree models than other method. Experimental results demonstrate that the proposed algorithm outperforms existing methods for private decision tree construction.