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THE use of liquid oxygen as an oxidizer for various fuels in liquid rocket propellent systems is not new. Professor Goddard used liquid oxygen in his rocket experiments and the well known German V‐2 rockets used this material as an oxidizer. However, its effect on non‐metallic materials ordinarily used in rocket systems was not investigated until recent years. This investigation was prompted by phenomena which had been experienced by rocket engine and rocket aircraft manufacturers and by suppliers of the material. It was observed that when some organic materials came in intimate contact with liquid oxygen they became prone to detonation when subjected to certain impact energies. This was undoubtedly due to the formation of unstable organo‐peroxide compounds which when impacted released high levels of energy resulting in an explosion. Specifically, when liquid oxygen was accidently spilled on asphalt and inadvertently stepped on, the asphalt would often explode. Also, leather gaskets immersed in liquid oxygen and subjected to surge impact detonated with disastrous effects.

In the paper the optimization procedure of a direct current motor with a hybrid excitation has been presented. The excitation system consists of a shunt field winding disposed around field pole and permanent magnet, both acting in parallel. The field distribution in motor for various magnet and field pole dimensions has been determined using finite element method. The flux linkage with the armature winding has been computed. Demagnetizing effect of armature current was taken into account. The optimal permanent magnet and the field pole dimensions, ensuring minimum total cost of purchase and work during assumed period of time were calculated. Motor characteristics e.g. rated torque, rated current, speed regulation limit were used as constraints. In worked up algorithm and computer program Carroll internal penalty function method was used. Some basic suggestions tor design of optimal hybrid excited dc motors with parallel permanent magnet and electromagnetic excitation are given.

I‐V characteristics of GaAs n‐i‐n structures are calculated by considering impact ionization of carriers. Impact ionization at reverse‐biased n‐i junction becomes a cause of steep current rise when an acceptor density in the i‐layer is high. It is shown that an optimum acceptor density exists to keep a good isolation. Photoconduction transients of GaAs n‐i‐n structures are also simulated, and are shown to be strongly affected by existence of n‐i junctions.

In the course of development of human communities towards industrially advanced societies of today, there have been changes not only in economic conditions in the majority of fields of human activity but also in the ways of providing for food, which went hand in hand with changes in living conditions. Large‐scale industrial production has brought about major changes in the way of life of the population. The development of industrial agglomerations results in a growing number of city dwellers, most of whom have no chance of producing foodstuffs of their own in kind. The distance between residential and industrial areas has been growing, the number of employed women has risen considerably. These are but a few factors affecting the way of boarding, particularly in households.

The Air Navigation regulations require that the certification of an aircraft before flight shall be made, in respect of the airframe, by an aircraft engineer licensed in Category “A” and in respect of the engines by an aircraft engineer licensed in Category “C”.

Argues in this wideranging paper that the legitimacy of international law depends on the principle that pacts should be respected, reviewing the issues of self‐preservation, proportionality and human rights in relation to this. Focuses on the economic war against terrorism by the USA preeminently, as expressed in the PATRIOT Act and the International Emergency Economic Powers Act and the Anti‐Terrorism and Effective Death Penalty Act. Concludes that the Patriot Act and the Homeland Security Act give the Executive branch of government extraordinary and warlike powers: but wars have an end whereas terrorism does not. Looks at the role of the US Federal courts in the context of national security, proportionality and human rights concerns, and finds them deficient; reports specific cases concerning Iranian resistance movements and their status as regards terrorism, and the Bajkajian, Austin and Alexander cases as regards proportionality.

Economic effects are only one aspect of the total impact of tourism. For example, the development of a tourist industry in a particular country has varying repurcussions on the long term socio‐cultural, environmental and ecological development of the local community as a whole. This article examines the main non‐economic aspects of tourism in Greece.

12,2 Millionen Bundesbürger sind über 60 Jahre alt. Im Jahre 2000 werden es bereits 14 Millionen sein. Kein Wunder also, dass die Senioren für viele Wirtschaftszweige immer interessanter werden. Dies gilt auch für die Tourismusbranche, die mit der wachsenden Reisefreude der älteren Generation rechnen kann. Im vorliegenden Beitrag werden ausgewählte Ergebnisse einer Studie wiedergegeben, die das Institut für Freizeit‐ und Tourismusberatung aus Ettlingen Anfang des Jahres gemacht hatte.

At the January meeting of the American Library Association in Washington, DC, IBM equipment and products led the field against Apple and other microcomputer brands. Predictions that the IBM PC would become the de facto standard library computer have clearly been fulfilled. It now appears that more powerful IBM products——such as the AT——and a host of peripherals will shortly become commonplace library equipment.

This second part of a companion paper seeks to extend the theory proposed to apply the hierarchy of fuzzy formal language to cope with the three major phenomenon of life: replication, control and shuffling of genetic information.

In order to cope with the proposal, three new classes of FFG are proposed: replicating grammars: to formalize properties and consequences of DNA duplication; self‐controlled grammars: to provide the tools to control the grammar ambiguity and to improve adaptability, and recombinant grammars: to formalize properties and consequences of the sexual reproduction to life evolution. Considering all these facts, FFG are proposed as the key instrument to formalize the basic properties of the chemical transactions supporting life.

The formalism of the model provides a new way to analyze and interpret the findings of the different genome sequencing projects.

The theoretical framework developed here provides a new perspective of understanding the code of life and evolution.