User Interfaces for Complex Engineering Software: Application of Virtual Reality

IT systems for engineers are becoming more numerous and complex and will further proliferate in the future. It is infeasible to expect users to be trained to work with a plethora of systems, especially as many of them will only see occasional use. Therefore, in the near future, systems will need user interfaces that allow intuitive access and usage. This paper examines a new style of user interface based on virtual reality.     

A comparative analysis of methods for pruning decision trees

In this paper, we address the problem of retrospectively pruning decision trees induced from data, according to a top-down approach. This problem has received considerable attention in the areas of pattern recognition and machine learning, and many distinct methods have been proposed in literature. We make a comparative study of six well-known pruning methods with the aim of understanding their theoretical foundations, their computational complexity, and the strengths and weaknesses of their formulation. Comments on the characteristics of each method are empirically supported. In particular, a wide experimentation performed on several data sets leads us to opposite conclusions on the predictive accuracy of simplified trees from some drawn in the literature. We attribute this divergence to differences in experimental designs. Finally, we prove and make use of a property of the reduced error pruning method to obtain an objective evaluation of the tendency to overprune/underprune observed in each method     

Localized dissection of the abdominal aorta. Diagnosis and surgical treatment

Abdominal aortic dissection is a rare pathology. As far as we are concerned, only 59 cases have been reported in the English literature. In the last two years, two cases were treated at our Institution. Both were males, over 70 years of age. They were evaluated with ultrasonography, angiography (1 case) and Magnetic Resonance Imaging which showed localised dissection of the abdominal aorta with aneurysmal dilatation. They underwent surgical treatment with good results. At 1 and 2 years from operation both patients are alive and well. A postoperative ultrasonography didn't show any residual dissection.     

Resonant Quantum Phenomena for an rf-SQUID: Moderate Underdamped and Extreme Underdamped Limit

We study the resonant quantum behaviour of a macroscopic superconducting system interacting with an external field. First we consider the resonant tunneling assisted by microwave frequency in the moderate underdamped quantum regime. Then we consider the resonant process in the extreme underdamped limit. In both regimes we have investigated a small frequency range, where resonant phenomena take place. The transition probability W from the left to the right potential well has been numerically calculated for an rf-SQUID as function of the external flux φ _x for both regimes. Results indicate that, in a proper frequency and φ _x range, the transition probability W can present two or three resonant peaks, depending on the damping regime.