Radio Proper Motions of Wolf-Rayet Stars

We present the analysis of observations taken from the Very Large Array archive of six Wolf-Rayet stars with radio emission, with the purpose of determining their proper motions. Typically, these observations cover periods of 10 to 20 years. To verify the method, we included WR 140 in the sample, finding that the proper motions determined by us are a few times more accurate than and consistent within noise with those of Hipparcos. The other five WR stars were not studied by Hipparcos and we report their proper motions for the first time. The proper motions for WR 145a = Cyg X-3 are consistent with the source being stationary with respect to its local standard of rest and suggest that the black hole in this binary system formed by direct collapse of a massive star, without expulsion of a supernova remnant.Comment: 12 pages, 7 figure

Comparison of Spatial Visualization Skills in Courses with Either Graphics or Solid Modeling Content

This paper presents a comparison made between visualization skills in a group of students that take a course with graphics topics, and those that take a course with solid modeling. The graphics course (2D) is in the context of manual drafting and a drafting software, while the solid modeling course (3D) in based on the utilization of concepts and software for solid modeling. The objective pursued is to identify any possible benefit, from the point of view of improved spatial visualization skills, from either of these two approaches. The visualization aptitude of the students was measured by administering the standard PSVT:R test before and after the respective topics were covered. This evaluation was done at two different academic institutions, with each one of the institutions using either a graphics or a solid modeling approach. Results from this study have relevance when defining course content, particularly with the current trend of including 2D and 3D topics in one single course. The result of the comparison indicates that although there are numeric differences between the two groups, particularly with standard deviations, they are not statistically significant to make a claim about the visualization skills of courses with 2D or 3D approach

Rigid-plastic finite element analysis of some metal forming processes

Imperial Users onl

Optimizing Wedding Venue Selection Process Using Integer Programming

Choosing the right wedding venue can be extremely difficult for the unsuspecting engaged couple. There is a myriad of variables that must be taken into account prior to the illustrious wedding date; these variables include the option for a reception, the location, and food requirements, to name a few. Consequently, the typical couple seems to spend multiple months researching and visiting many wedding spaces. However, even though months go into planning, it still is not a guarantee that all variables are accounted for. Furthermore, without a wedding planner, these couples may second-guess their chosen site due to seemingly arduous issues with their venue. Even when a wedding planner is available, their services can be extremely expensive, and this still does not guarantee the perfect wedding; these issues add a layer of difficulty to the wedding planning process—due to the differing values of couples. This project aims to use a mathematical framework to model and generalize the wedding venue selection process. The resulting model can be used to model the venue selection process in the future and help the planning process become more efficient and repeatable. The model follows numerous constraints in order to maximize the utility gained by the author and his fiancé. This model is implemented on the IBM ILOG CPLEX Optimization Studio. The results from this model provide an optimal wedding venue and the number of guests that should be invited

Quantum coherence, correlated noise and Parrondo games

We discuss the effect of correlated noise on the robustness of quantum coherent phenomena. First we consider a simple, toy model to illustrate the effect of such correlations on the decoherence process. Then we show how decoherence rates can be suppressed using a Parrondo-like effect. Finally, we report the results of many-body calculations in which an experimentally-measurable quantum coherence phenomenon is significantly enhanced by non-Markovian dynamics arising from the noise source.Comment: 8 page