Points to be considered in thermogravimetry

Continuous thermogravimetry is a common method to test materials in gaseous corrosive environments at high temperatures and to elucidate kinetics and mechanisms of high temperature corrosion. Recommendations how to conduct thermogravimetric tests are collected here, points to be considered including sample size and form, surface preparation, reaction chamber, starting procedure, sensitive measurements, gas supply and dosing. This study is meant as a starting foundation for establishing guidelines in high temperature corrosion research.     

The control of acid mine drainage with Wetlands

The recent increases in environmental legislation, especially in the USA have meant that there is a need on behalf of the mining companies for more judicious operational planning and more thorough restoration techniques in order to reduce costs and prevent violation of the strictly enforced regulations. Water pollution is probably the greatest problem and many less enlightened operators, especially for example, in surface coal milling in Pennsylvania, have been forced into liquidation after having been unable to meet the severe restrictions on Acid Mine Drainage (AMD). The problems of AMD are also inherent in most forms of metalliferous and coal mining and also in some types of aggregate quarrying. As excavations go deeper in search of ever diminishing reserves then they are more likely to encounter groundwater which can become polluted if insufficient care is not taken. It is to be expected that the laws will also become more severe than they are at present in Europe and methods of treatment of AMD will need to be developed that are more efficient than the costly chemical methods currently used. Research by the author and others into the source of AMD pollution and its treatment with engineered wetlands and other operational methods are discussed in the paper. The methods have- the distinct benefit that they are cheap to install, are cost effective over a long period with the minimum of supervision and are environmentally acceptable to the planning and regulatory authorities.     

Computer Simulation of Structural Aspects of Enantioselective Heterogeneous Catalysis and the Prospects for Direct Calculation of Selectivity

We review simulation work on the structure of enantioselective heterogeneous catalysts and the ability of this work to qualitatively rationalize the sense of the selectivity observed. Kinetic models are then presented to show how the quantitative enantioselectivity depends on energetic differences in the reaction pathways for the two enantiomers during adsorption and surface reaction. In the light of these calculations, the reliability of direct calculation of ee is discussed.     

Influence of cerium implantation on the nucleation and growth of corrosion products on alloy 800H in a mixed sulphidizing/oxidizing environment

The influence of implantation of cerium on the corrosion behavior of an 32Ni-20Cr austenitic steel, Alloy 800H, in a simulated coal-gasification atmosphere has been examined at 700°C. The composition and microstructure of the corrosion products formed after exposure periods between 1 min and 200 h were examined with a range of surface-analytical techniques. The corrosion mechanism of Alloy 800H was characterized as a mixture of oxidation and sulphidation, primarily of Cr and Fe. The oxides provided protection against catastrophic sulphidation. Cerium implantation reduced the corrosive attack, providing the dose was sufficient. The corrosion was more uniform and the products had a higher Cr/Fe ratio compared to those on the unimplanted alloy. It is proposed that these changes resulted from the formation of a more protective and more stable oxide layer, due to the rapid formation of ceria particles, specifically hindering the formation of the less-stable oxides and sulphides.     

Microwave densification of electrophoretically infiltrated silicon carbide composite

A new method to fabricate SiC composites by microwave heating SiC preforms is described. Preforms were produced by electrophoretically infiltrating SiC fibre (Nicalon) preforms with SiC powder. Samples were heated to 1600°C in a matter of minutes and held at temperature for 5 min to minimize fibre degradation. To achieve densification, heated preforms required the application of a uniform load. Bulk densities increased from ∼ 0.8 gcm-3 for the as-infiltrated preforms to over 1.9 gcm-3 for microwave-heated samples with a small applied load of ∼13 kPa. Microstructural analysis revealed the presence of some pores and cracks in the matrix; however, large areas of dense SiC matrix material are apparent. This revised version was published online in November 2006 with corrections to the Cover Date.     

Planning,Law, and Property Rights: A US–European Cross-national Contemplation

Globalization today encompasses multinational dialogues on the appropriate role for planning in mediating relationships between individual and community, state and citizen, government and market, and people and property. Yet confusion persists as speakers from one country attempt to convey concepts different from what listeners from another country hear. This paper provides a cross-national contemplation on the sources of that confusion, comparing the USA to Western Continental Europe, primarily Germany. Americans and Europeans engage fundamentally different worldviews in promoting progress while reconciling harms, stemming from different philosophical traditions that can be broadly characterized as a Millian versus a Hegelian liberalism, respectively.     

Long-term validated simulation of a building integrated photovoltaic system

Electrical and thermal simulations of a building integrated photovoltaic system were undertaken with a transient system simulation program using real field input weather data. Predicted results were compared with actual measured data. A site dependent global-diffuse correlation is proposed. The best-tilted surface radiation model for estimating insolation on the inclined surface was selected by statistical tests. To predict the module temperature, a linear correlation equation is developed which relates the temperature difference between module and ambient to insolation. Different combinations of tilted surface radiation model, global-diffuse correlation model and predicted module temperature were used to carry out the simulation and corresponding simulated results compared with the measured data to determine the best combination which gave the least error. Results show that modification of global-diffuse correlation and module temperature prediction improved the overall accuracy of the simulation model. The monthly error between measured and predicted PV output was lied below 16%. Over the period of simulation, the monthly average error between measured and predicted PV output was estimated to be 6.79% whereas, the monthly average error between measured and predicted inverter output was 4.74%.     

Effect of glass thickness on the thermal performance of evacuated glazing

Flat evacuated glazing consists of two plane glass panes separated by a narrow internal evacuated space. Separation in the space is maintained by an array of support pillars typically 0.32 mm in diameter and 0.12 mm high arranged on a regular square grid with an inter-pillar separation of up to 40 mm. A detailed three-dimensional finite volume model has been employed to determine the variation of thermal performance of an evacuated glazing as a function of glass pane thickness. It was predicted that for evacuated glazing of dimensions of 0.3 m by 0.3 m and 0.5 m by 0.5 m, reducing glass pane thickness gave improved thermal performance. For evacuated glazings with dimensions of 1 m by 1 m, the opposite was predicted.