CAL production: Strategies and tactics

There is a world-wide hunger for CAL material. It is born of the same causes as the thirst for open and distance learning. Funding agencies and administrations at all levels from individual institutions to national governments want to believe that these technologies can solve their problems. This is evidenced by reports from and discussions with relevant authorities as far apart as Scandinavia, Central Africa and South East Asia. A worrying feature is the number of occasions when the focus of the discussions is on the translation or conversion of existing CAL or the coordination of CAL production by other agencies. This is understandable in terms of the scale of the need and the limited resources available to education. but who funds the producers?The paper looks at the strategy adopted in Scotland for the production of CAL material for schools. It reports on proposals for the Further Education Sector and takes the Scottish Action Plan for modular courses as a basis for estimating the costs of CAL on a national scale.Individuals and institutions cannot wait for such schemes to be implemented and the contributors to the conference show the breadth and depth of commitment to CAL throughout the world. Even so the investment of effort is such as to demand team activity. For the average teacher, conventional CAL is still too demanding of time, even given the improvements in authoring languages and software tools. The paper suggests that the growing use of commercial packages as content free software allows individuals to make limited but useful contributions within their own cumcular framework, integrating the computer into the learning process.Neither the strategic nor the tactical approaches will solve all our problems, and the extent to which we cooperate is a key factor. Some proposals for improving this sharing are offered.     

Mathematical aspects of qualitative reasoning

Variations of interval arithmetic are developed in order to formalize the qualitative calculi used in ENVISION, Qualitative Process Theory, and QSIM. Properties such as completeness and soundness of these methods are analysed. The qualitative calculi are shown to be complete, but not sound. This means that these qualitative reasoning methods might predict spurious states of systems. Furthermore, their results are sensitive to transformations applied to the underlying equations.     

Data processing system for the management of experiments on electrochemical generators

This paper describes a data acquisition and test monitoring system designed to manage electrochemical tests of secondary batteries and of their cathodic materials. The software developed allows various protocols for galvanostatic cycling as a function of time or of voltage, as well as for charge-discharge steps associated with relaxation periods. The software package has been used on a time-sharing mini-computer. Thus, while data collection is in progress, one can examine graphically in real time the voltage evolution and the relaxation kinetics of the material under study.     

Catalytic activity of aluminium form of Y-type zeolites for the Claus reaction

Y-type zeolites modified with aluminium and activated at temperature below 470 K has bee found to be an effective catalyst for the Claus reaction. The activity of this modified form is higher than that of NaY pretreated under the same conditions. The basic OH groups are believed to be active centers involved in the catalytic process. Removal of these groups by means of high-temperature treatment or fluorination of the sample brings about a considerable decrease in the catalytic activity.     

Power system self-excitation online security assessment

Power system online security assessment is a significant new approach for power system operation. A new pattern-recognition-based application for power system security assessment is described. Here, the method is applied to the power system self-excitation operating problem. The security function used has the learning capacity to adapt to different network configurations and to new load and generation schedules. This paper relates to online security assessment and the corrective actions required. The system under study is the northern collector system for Manitoba Hydro, where self-excitation is a serious operating problem.     

The electrochemical performance of melt-spun C14-Laves type TiZr-based alloy

The main objective of the present work is to study the effect of rapid solidification on the electrochemical performance of Zr-based Laves type alloy with a nominal composition Ti₁₂Zr_21.5V₁₀Cr_7.5Mn_8.1Co₈Ni_32.2Al_0.4Sn_0.3. The samples were prepared from the as-cast arc melted buttons by melt spinning at different copper wheel rotation speeds of 5, 16.5, 33, and 100 Hz, which are equivalent to linear speeds of 6.3, 21, 41, and 62.8 m s⁻¹ respectively using a cooling wheel with a diameter of 20 cm. The phase composition and morphology of the ribbons were analyzed by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructural changes of the ribbons induced by the variations in the wheel rotation speed were found to be closely related to the electrochemical performances. High discharge capacities exceeding 400 mAh∙g⁻¹ were achieved for the melt spun samples during the measurements at low current densities. Furthermore, melt spun casting performed at the highest wheel rotation speed of 100 Hz resulted in the best rate performance of the alloy. As this alloy has the smallest crystallite size, this resulted in the shortest H atoms diffusion distances, and thus increased the efficient H diffusion rate and improved the electrochemical performance.     

Children's blood lead and exposure to lead in household dust and water — a basis for an environmental standard for lead in dust

Good quantitative evidence on the role of lead in household dust as a source of exposure to children has been lacking. A study of 495 children in Edinburgh, Scotland shows a significant relationship between lead in dust vacuumed from the floors of the children's homes and their blood lead levels. A multiple regression analysis incorporating drinking water and household dust estimates that a 1,000 μg g⁻¹ increase in dust lead concentration would increase blood lead by 1.9 μg dl⁻¹, for a child with the median population blood lead of 10.1 μg dl⁻¹. Dust lead concentration is a more useful predictor of blood lead than lead loading. The sanding or blow-lamp stripping of old paint is found to be an important source of the higher household dust lead concentrations. Finally, the dust lead-blood lead relationship is used to derive a standard for lead in house dust, as no such standard exists for this exposure route.     

Unidirectional wavelength filtering characteristics of the two-dimensional triangular-lattice photonic crystal structures with elliptical defects

The unidirectional wavelength filtering characters of the two-dimensional triangular-lattice photonic crystal structures consisting of two waveguides and an elliptic defect are theoretically studied by the finite-difference time-domain method. Through designing the coupling regions between the elliptical defect and the adjacent waveguides, the unidirectional wavelength filtering is achieved owing to the modes’ match and mismatch between the elliptical defect and waveguides, which converts the incident fundamental even-symmetric modes to the higher order odd modes. Based on the abundant defective modes with different symmetries supported by the elliptical defect, this kind of wavelength filters can allow the unidirectional light propagation with inverse forward directions, and the bidirectional propagation through the same structure at different wavelengths.     

Investigating the effects of microstructure on the wear mechanisms in lamellar cast irons via microscratch tests

This work investigates the effects of microstructure on the wear mechanisms in lamellar cast irons using a microscratch test. Various applied loads and indenter geometries were utilised. The results indicate that the surface damage depends on the indenter geometry, the penetration depth, the orientation and the depth of the graphite flakes. Increasing the applied load and the attack angle increases the friction coefficient, the tangential force and its fluctuation. Beyond a certain load, the friction coefficient remains nearly constant. The proposed schemes explain the role played by both the matrix and graphite in the wear process.