Continuation methods for approximate large scale object sequencing

Machine Learning - We propose a set of highly scalable algorithms for the combinatorial data analysis problem of seriating similarity matrices. Seriation consists of finding a permutation of data...     

Production of hydrogen for fuel cells by reformation of biomass-derived ethanol

The reformation of biomass-derived ethanol to a hydrogen-rich gas stream suitable for feeding fuel cells is investigated as an efficient and environmentally friendly process for the production of electricity for mobile and stationary applications. Steam reforming of ethanol is investigated over Ni catalysts supported on La₂O₃, Al₂O₃, YSZ and MgO. The influence of several parameters on the catalytic activity and selectivity is examined including reaction temperature, water-to-ethanol ratio and space velocity. Results reveal that the Ni/La₂O₃ catalyst exhibits high activity and selectivity toward hydrogen production and, most important, long term stability for steam reforming of ethanol. The enhanced stability of this catalyst may be due to scavenging of coke deposition on the Ni surface by lanthanum oxycarbonate species which exist on top of the Ni particles under reaction conditions.     

Effective visualization of complex vascular structures using a non-parametric vessel detection method

The effective visualization of vascular structures is critical for diagnosis, surgical planning as well as treatment evaluation. In recent work, we have developed an algorithm for vessel detection that examines the intensity profile around each voxel in an angiographic image and determines the likelihood that any given voxel belongs to a vessel; we term this the "vesselness coefficient" of the voxel. Our results show that our algorithm works particularly well for visualizing branch points in vessels. Compared to standard Hessian based techniques, which are fine-tuned to identify long cylindrical structures, our technique identifies branches and connections with other vessels. Using our computed vesselness coefficient, we explore a set of techniques for visualizing vasculature. Visualizing vessels is particularly challenging because not only is their position in space important for clinicians but it is also important to be able to resolve their spatial relationship. We applied visualization techniques that provide shape cues as well as depth cues to allow the viewer to differentiate between vessels that are closer from those that are farther. We use our computed vesselness coefficient to effectively visualize vasculature in both clinical neurovascular x-ray computed tomography based angiography images, as well as images from three different animal studies. We conducted a formal user evaluation of our visualization techniques with the help of radiologists, surgeons, and other expert users. Results indicate that experts preferred distance color blending and tone shading for conveying depth over standard visualization techniques.     

Production of hydrogen for fuel cells by steam reforming of ethanol over supported noble metal catalysts

The catalytic performance of supported noble metal catalysts for the steam reforming (SR) of ethanol has been investigated in the temperature range of 600–850 °C with respect to the nature of the active metallic phase (Rh, Ru, Pt, Pd), the nature of the support (Al₂O₃, MgO, TiO₂) and the metal loading (0–5 wt.%). It is found that for low-loaded catalysts, Rh is significantly more active and selective toward hydrogen formation compared to Ru, Pt and Pd, which show a similar behavior. The catalytic performance of Rh and, particularly, Ru is significantly improved with increasing metal loading, leading to higher ethanol conversions and hydrogen selectivities at given reaction temperatures. The catalytic activity and selectivity of high-loaded Ru catalysts is comparable to that of Rh and, therefore, ruthenium was further investigated as a less costly alternative. It was found that, under certain reaction conditions, the 5% Ru/Al₂O₃ catalyst is able to completely convert ethanol with selectivities toward hydrogen above 95%, the only byproduct being methane. Long-term tests conducted under severe conditions showed that the catalyst is acceptably stable and could be a good candidate for the production of hydrogen by steam reforming of ethanol for fuel cell applications.     

Ballistic Transport in Classical and Quantum Integrable Systems

In this essay, we first sketch the development of ideas on the extraordinary dynamics of integrable classical nonlinear and quantum many body Hamiltonians. In particular, we comment on the state of mathematical techniques available for analyzing their thermodynamic and dynamic properties.Then, we discuss the unconventional finite temperature transport of integrable systems using as example the classical Toda chain and the toy model of a quantum particle interacting with a fermionic bath in one dimension; we focus on the singular long time asymptotic of current-current correlations, we introduce the notion of the Drude weight and we emphasize the role played by conservation laws in establishing the ballistic character of transport in these systems.     

Computer user training and attitudes: a study of business undergraduates

For many users, the first real encounter with a computer occurs when taking an introductory course to computers at a college. To the extent that these training courses impact user understanding and motivation, they are important determinants of the user attitudes towards computers and merit serious assessment. Using 327 business undergraduates at two universities in the US, this paper reports on the reactions of students to computers and computer-related tasks before and after an introductory course to computers. Responses to a 20-item scale were analysed to examine the pattern of attitude change experienced by students in their training course. Factor analysis revealed five constructs for describing patterns of computer user attitude: negative reaction to computers; positive reaction to computers; reaction to computers for children education; reaction to computer-mediated services; and reaction to computer games. Four factors show significant change in mean scores after the training courses. The attitudes changed for males more than females, indicating improvement in attitudes. The respondents' attitude to computer-mediated services remained unchanged. While the directions of changes indicate an overall improvement in respondents' reactions, many attitudes did not change significantly after having taken the training courses. This may be due to the content or the format of these courses.     

Effect of Electronic Properties of Catalysts for the Oxidative Coupling of Methane on Their Selectivity and Activity

The oxidative coupling of methane (OCM) to higher hydrocarbons may eventually become an interesting alternative for the chemical utilization of natural gas. Extensive studies have been conducted since the works of Keller and Bhasin [l] and of Hinsen and Baerns [2].     

Heat transport limitations and reaction scheme of partial oxidation of methane to synthesis gas over supported rhodium catalysts

The partial oxidation of methane to synthesis gas over supported Rh catalysts is investigated, paying particular attention to removing heat transport limitations and identifying the reaction conditions within the kinetic-controlling regime. The results obtained suggest that the reaction follows the sequence of total oxidation to CO₂ and H₂O, followed by reforming reactions to synthesis gas.     

Shape from interaction

We present “shape from interaction” (SfI), an approach to the problem of acquiring 3D representations of rigid objects through observing the activity of a human who handles a tool. SfI relies on the fact that two rigid objects cannot share the same physical space. The 3D reconstruction of the unknown object is achieved by tracking the known 3D tool and by carving out the space it occupies as a function of time. Due to this indirection, SfI reconstructs rigid objects regardless of their material and appearance properties and proves particularly useful for the cases of textureless, transparent, translucent, refractive and specular objects for which there exists no practical vision-based 3D reconstruction method. Additionally, object concavities that are not directly observable can also be reconstructed. The 3D tracking of the tool is formulated as an optimization problem that is solved based on visual input acquired by a multicamera system. Experimental results from a prototype implementation of SfI support qualitatively and quantitatively the effectiveness of the proposed approach.     

Physiological effects of "hypnotic suggestions': A critical review of recent research (1960-64).

Recent studies are reviewed which were concerned with the effectiveness of suggestions given under "hypnosis" and "waking" experimental treatments in alleviating allergies, ichthyosis, myopia, and other conditions and in eliciting deafness, blindness, hallucinations, analgesia, cardiac acceleration and deceleration, emotional responses, urine secretion to sham water ingestion, narcotic-like drug effects, and other phenomena. The review indicates that a wide variety of physiological functions can be influenced by suggestions administered under either hypnosis or waking experimental treatments, and direct and indirect suggestions to show the particular physiological manifestations are crucial variables in producing the effects. (3 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)