7,864 research outputs found

    The Assessment of Teaching Practice : What criteria should we choose?

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    For a number of years now, the practical element of pre-service teacher education has been taken in primary and secondary schools under the guidance of members of the school staff, and tutors from the college or university department of education. The tutor may also be called upon to give an assessment of the student\u27s ability to teach. Despite various attempts to break away from assessments by grading, the fact remains that the majority of student-teachers practise are assessed this way. The recurrent problem, then, is on what criteria should the assessment be based

    Towards optimized suppression of dephasing in systems subject to pulse timing constraints

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    We investigate the effectiveness of different dynamical decoupling protocols for storage of a single qubit in the presence of a purely dephasing bosonic bath, with emphasis on comparing quantum coherence preservation under uniform vs. non-uniform delay times between pulses. In the limit of instantaneous bit-flip pulses, this is accomplished by establishing a new representation of the controlled qubit evolution, where the resulting decoherence behaviour is directly expressed in terms of the free evolution. Simple analytical expressions are given to approximate the long- and short- term coherence behaviour for both ohmic and supra-ohmic environments. We focus on systems with physical constraints on achievable time delays, with emphasis on pure dephasing of excitonic qubits in quantum dots. Our analysis shows that little advantage of high-level decoupling schemes based on concatenated or optimal design is to be expected if operational constraints prevent pulses to be applied sufficiently fast. In such constrained scenarios, we demonstrate how simple modifications of repeated periodic echo protocols can offer significantly improved coherence preservation in realistic parameter regimes.Comment: 13 figures,1 tabl

    Numerical investigation of high and low pressure tube hydroforming

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    Hydroforming is one option to reduce vehicle weight while increasing component stiffness and rigidity. This typically involves using a fluid to form a component with high internal pressure. Tube hydroforming has gained increasing interest in the automotive and aerospace industries because of its many advantages such as part consolidation, good quality of the formed part etc. The main advantage is that the uniform pressure can be transferred to whole part at the same time. In low pressure hydroforming, the internal pressure is significantly and the hydroformed section length of line stays almost the same as the circumference of the blank tube. This paper details the comparison between high and low pressure hydroforming. It is shown that the internal pressure and holding force required for low pressure hydroforming process is much less than that of high pressure. Also stress and thickness distribution are more uniform and the process is highly suitable for the forming of advanced high strength steels.<br /

    An investigation of complex shapes during low pressure tube hydroforming

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    Hollow structures made of Advanced High Strength Steel (AHSS) are increasingly used in the automobile industry for crash and structural components. Generally high pressure hydroforming is used to form these tabular parts, which is a costly manufacturing process due to the high pressure equipment and large tonnage presses required. A new process termed low pressure hydroforming, where a pressurized tube is crushed between two dies, represents a more cost effective alternative due to the lower pressures and die closing forces required.In this study the low pressure tube hydroforming of one simple and two different complex hollow shapes is investigated. The complexities of the pat1S compared to simple shapes are critically studied and the die filling conditions are investigated and discussed. FUl1hennore the thickness distributions over the circumference of the part during forming are analyzed.<br /

    Influence of trust in institutions on public acceptance of nuclear power from a historical context across nuclear countries

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    Several studies have tried to determine what is behind peoples’ attitudes to different energy sources and their overall rather negative opinion on nuclear power. The issue of public perception of nuclear power has been going on for decades. Recently it gained even greater interest thanks to the support of the UK governmental nuclear industrial strategy to promote and support nuclear growth. Nuclear power is negatively influenced by events from the past such as nuclear accidents and connection of nuclear power with cold war and the use of nuclear bombs. As one of many other factors, the level of trust in authorities is perceived to influence the opposition or support for nuclear power. This study aims at analyzing data on trust in four main institutions (government, businesses, media and non-governmental organizations) from a historical perspective in several nuclear countries and finding evidence for relationship between trust in authorities and support for nuclear power. Structural Equation Modelling and Multiple Regression Analysis have been used to analyze data Structural Equation modelling requires a large sample set to provide meaningful results, therefore performance can deteriorate when sample size reduces. Hence, Multiple Regression analysis has been carried out. Results from Multiple Regression analysis did not prove that the trust in institutions is significant predictor of support for nuclear power. Although around 55% of variance in support for nuclear was explained by trust institutions in UK as well as in USA case. Large sample size is required to authenticate model and obtain more robust results. It is likely that Multiple Regression analysis will be used for future data analyses when more data will be available

    Nuclear symmetry energy and its density slope at normal density extracted from global nucleon optical potentials

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    Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy Esym(ρ)_{sym}(\rho) and its density slope L(ρ)L(\rho) at normal density ρ0\rho_0 are completely determined by the global nucleon optical potentials that can be extracted directly from nucleon-nucleus scatterings, (p,n) charge exchange reactions and single-particle energy levels of bound states. Adopting a value of m/m=0.7m^*/m=0.7 for the nucleon effective k-mass in symmetric nuclear matter at ρ0\rho_0 and averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of Esym(ρ0)=31.3E_{sym}(\rho_0)=31.3 MeV and L(ρ0)=52.7L(\rho_0)=52.7 MeV are simultaneously obtained. Uncertainties involved in the estimates are discussed.Comment: 4 pages including 2 figure

    Multi-scale modelling of DP590 steel

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    Dual Phase (DP) steel one of the Advanced High Strength Steels (AHSS) has a two phase microstructure where soft and hard phase acts together to offer a high strength composite effect. The high strength, however, must be balanced with ductility so that complex parts and designs can be manufactured from AHSS sheets. However, during forming certain grades of DP steel a sudden crack can occur without any intimation of necking. Thus, due to this abnormal forming behaviour, is difficult to accurately predict because most classical modelling approaches are not designed for such micro-structurally heterogeneous materials. These modelling approaches are generally based on an average representation of the material behaviour in a continuum mechanics formulation. This works for materials that are homogenous, or at least could be assumed to be homogenous at scales lower than the naked eye can see. However, for a material like AHSS, the microstructure plays a significant role in dictating the mechanical behaviour at the macro-scale. This paper studies the multi-scale modelling ofDP590 steel. It is found that the sufficient accuracy can be achieved from multi-scale modelling while comparing with the experiments.<br /

    The Assessment of Teaching Practice : What criteria should we choose?

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    For a number of years now, the practical element of pre-service teacher education has been taken in primary and secondary schools under the guidance of members of the school staff, and tutors from the college or university department of education. The tutor may also be called upon to give an assessment of the student\u27s ability to teach. Despite various attempts to break away from assessments by grading, the fact remains that the majority of student-teachers practise are assessed this way. The recurrent problem, then, is on what criteria should the assessment be based

    長崎函館滞在記1859-1860

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