Thesis--Copenhagen. / Summary in English. Bibliography: p. 384-401.

Double-enveloping reducer is widely used in the industry due to its high transmission torque and high accuracy. The screw theory and the rigid-body transformation method are introduced and applied in this thesis to the determination of the worm surface. The equation of the worm surface is derived by the two methods based on different geometries of cutting tools (conical cutter and fly cutter). According to the Standards of American Gear Manufacturers Association (AGMA6030 C-87), the size and the shape of the cutters can be determined to conform the worm offset surface. Moreover, a measuring system is set up with a CMM (coordinate measuring machine) to measure and record the center point of the touch probe when it contacts with the surface of the double-enveloping worm. Finally, comparisons of measured results with different theoretical worm offset surfaces obtained from two types of cutting tools are made in this study. Geometric errors of the measured worm offset surface shows that the worm used in this thesis was machined by cutters with a conical form.

Worms have caused significant destruction over the last few years. Network security elements such as firewalls, IDS, etc have been ineffective against worms. Some worms are so fast that a manual intervention is not possible. This brings in the need for a stronger security architecture which can automatically react to stop worm propagation. The method has to be signature independent so that it can stop new worms. In this thesis, an automated defense system (ADS) is developed to automate defense against worms and contain the worm to a level where manual intervention is possible. This is accomplished with a two level architecture with feedback at each level. The inner loop is based on control system theory and uses the properties of PID (proportional, integral and differential controller). The outer loop works at the network level and stops the worm to reach its spread saturation point. In our lab setup, we verified that with only inner loop active the worm was delayed, and with both loops active we were able to restrict the propagation to 10% of the targeted hosts. One concern for deployment of a worm containment mechanism was degradation of throughput for legitimate traffic. We found that with proper intelligent algorithm we can minimize the degradation to an acceptable level.

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The work presented in this thesis consists of an investigation into the development of the female reproductive system of the human blood fluke Schistosoma mansoni. Worms were examined both under the light and electron microscopes, at all ages from 20 to 70 days post-infection. An investigation was also carried out into the various factors which affect the rate of development of the reproductive system. The development of the female system as a whole, as observed under the light microscope, is examined in Chapter 1, with a detailed examination of the ultrastructural development of each individual section of the system as observed using the electron microscope being presented in the succeeding chapters. Several factors were found to have an effect on the development of the female worms. These were the age of the worms themselves, the sex-ratio of the population as a whole and the population size. However, only the first two factors were found to effect the sexual development, the population size only affecting the overall size of the worms. The ultrastructure of the various components of the female reproductive system was observed at ages ranging from 20 to 70 days post-infection and the method of development of each component has been described as far as possible.

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