The Use of Explosive Forming for Fastening and Joining Structural and Pressure Components

Explosive expansion of tubes into tubesheets has been used for over 20 years in the fabrication and repair of shell and tube heat exchangers. The use of explosives to perform these expansions has offered several distinct advantages over other methods. First, the process is fast and economical and can be performed with minimal training of personnel. Secondly, explosive forming does not cause the deleterious metallurgical effects which often result from other forming operations. In addition, the process can be performed remotely without the need for sophisticated handling equipment. The expansion of tubes into tubesheets is only one of many possible fastening and joining applications for which explosive forming can be used to achieve highly successful results. The explosive forming process and where it has been used are described. In addition, some possible adaptations to other joining applications are identified and discussed

Limit cycles of a perceptron

An artificial neural network can be used to generate a series of numbers. A boolean perceptron generates bit sequences with a periodic structure. The corresponding spectrum of cycle lengths is investigated analytically and numerically; it has similarities with properties of rational numbers.Comment: LaTeX and 4 postscript pages of figure

Justice and the Convention on Biological Diversity

Benefit sharing as envisaged by the 1992 Convention on Biological Diversity (CBD) is a relatively new idea in international law. Within the context of non-human biological resources, it aims to guarantee the conservation of biodiversity and its sustainable use by ensuring that its custodians are adequately rewarded for its preservation. Prior to the adoption of the CBD, access to biological resources was frequently regarded as a free-for-all. Bioprospectors were able to take resources out of their natural habitat and develop commercial products without sharing benefits with states or local communities. This paper asks how CBD-style benefit-sharing fits into debates of justice. It is argued that the CBD is an example of a set of social rules designed to increase social utility. It is also argued that a common heritage of humankind principle with inbuilt benefit-sharing mechanisms would be preferable to assigning bureaucratic property rights to non-human biological resources. However, as long as the international economic order is characterized by serious distributive injustices, as reflected in the enormous poverty-related death toll in developing countries, any morally acceptable means toward redressing the balance in favor of the disadvantaged has to be welcomed. By legislating for a system of justice-in-exchange covering nonhuman biological resources in preference to a free-for-all situation, the CBD provides a small step forward in redressing the distributive justice balance. It therefore presents just legislation sensitive to the international relations context in the 21st century