Using obstacle analysis to identify contingency requirements on an unpiloted aerial vehicle

This paper describes the use of Obstacle Analysis to identify anomaly handling requirements for a safety-critical, autonomous system. The software requirements for the system evolved during operations due to an on-going effort to increase the autonomous system’s robustness. The resulting increase in autonomy also increased system complexity. This investigation used Obstacle Analysis to identify and to reason incrementally about new requirements for handling failures and other anomalous events. Results reported in the paper show that Obstacle Analysis complemented standard safety-analysis techniques in identifying undesirable behaviors and ways to resolve them. The step-by-step use of Obstacle Analysis identified potential side effects and missing monitoring and control requirements. Adding an Availability Indicator and feature-interaction patterns proved useful for the analysis of obstacle resolutions. The paper discusses the consequences of these results in terms of the adoption of Obstacle Analysis to analyze anomaly handling requirements in evolving systems.     

Mesh segmentation using feature point and core extraction

Mesh segmentation has become a necessary ingredient in many applications in computer graphics. This paper proposes a novel hierarchical mesh segmentation algorithm, which is based on new methods for prominent feature point and core extraction. The algorithm has several benefits. First, it is invariant both to the pose of the model and to different proportions between the model’s components. Second, it produces correct hierarchical segmentations of meshes, both in the coarse levels of the hierarchy and in the fine levels, where tiny segments are extracted. Finally, the boundaries between the segments go along the natural seams of the models.     

Oxidation of organic pollutants in aqueous solutions by nanosized copper oxide catalysts

The catalytic activity of copper oxide nanoparticles was investigated for the removal of organic pollutants in aqueous solutions, using hydrogen peroxide as an oxidant. Complete degradation of both alachlor and phenanthrene was achieved after 20 min. The kinetics of the reaction was found to be pseudo-first-order with respect to the pollutant. The influence on the reaction kinetics of different catalyst samples, consisting of the same material but of different origin and different particle properties, was examined. The effects of several factors such as irradiation, oxidant concentration, ionic strength and pH on the reaction were also investigated. The catalysis is not photo-induced and can be performed without UV–vis irradiation. In particular, an optimal oxidant concentration was determined for the studied system. The presence of salts was found to inhibit the alachlor degradation rate. The addition of high concentrations of oxidant or salt results in pseudo-zero-order kinetics. However, NaCl at very high concentrations (>1 M) was found to cause a dramatic increase in reaction rate. The catalysis is efficient over a wide range of pH values.     

Stereoselective Total Synthesis of (±)-Ptilocaulin and its 7-Epimer. A Strategy Based On the Use of an Intramolecular Nitrile Oxide Olefin Cycloaddition (INOC) Reaction

A stereoselective total synthesis of (±)-ptilocaulin 1 , an antimicrobial anticancer agent as well as of its 7-epimer 23 is described. The strategy involves an aldol condensation of the dilithio dianion of the Z-aldoxime ( 13 ) with a ketone 6 to produce 11 and the stereospecific intramolecular cycloaddition of the nitrile oxide 5 , generated in situ from 11. The resulting isoxazoline 4 was converted to hydroxy ketone 3 which serves as a starting point for introduction of the fourth stereocenter at C-7. Lithium in ethylamine reduction of 3 produces stereospecifically the 7β-methyl compound which leads to ptilocaulin 1 , while catalytic hydrogenation of 3 introduces the 7α-methyl substituent and finally 7-epiptilocaulin 23. H- and C NMR analysis permits differentiation between isomers of intermediates. When, in the last step of the synthesis of 1 or 23 from 19 or 22 and guanidine, a higher temperature (>130 °C) was applied, an interesting disproportionation to aminopyrimidine 25 or 28 and cyclic guanidine 24 or 27 was observed.     

Paper craft models from meshes

This paper introduces an algorithm for segmenting a mesh into developable approximations. The algorithm can be used in various applications in CAD and computer graphics. This paper focuses on paper crafting and demonstrates that the algorithm generates approximations that are developable, easy to cut, and can be glued together. It is also shown that the error between the given model and the paper model is small.     

Synchronization characteristics of controllable oscillators

This paper considers the problem of synchronizing a controllable oscillator with some external frequency and determines the conditions for synchronization. The requirements are determined analytically and the results are applied to several examples in various fields.     

Can a one-day conference change female high school students' perception of electrical engineering?

This short paper focuses on an annual one-day conference that aims at exposing female high school students, who excel in mathematics, to the discipline of Electrical Engineering (EE). The findings presented in this short paper reinforce observations previously published at length in IEEE Transactions on Education.     

Salt‐Controlled Selectivity in “on Water” and “in Water” Passerini‐Type Multicomponent Reactions

We have demonstrated that simple sodium salts can completely reverse the product ratios of the Passerini reaction in aqueous media. Furthermore, the use of the “salting‐in” salt and a small excess of the nucleophile gives significantly higher yields than the use of the saturated solution of the nucleophile alone.     

Emulsions stabilization by lactoferrin nano-particles under in vitro digestion conditions

In recent years there has been a spur of interest in the utilization of nano and micro-particles to fabricate novel food-grade Pickering emulsions. Aligned with increased interest and efforts to promote health through food, this study aimed to extend the understanding of Pickering emulsions stabilized by lactoferrin (LF) nano-particles in respect to their stability and responsiveness to physiological conditions of the human mouth and stomach. Analytical centrifugation revealed that LF nano-particles did not alter mean droplet size of coarse emulsions but significantly (p < 0.05) reduced creaming rates by an order of magnitude. In fine emulsions produced through high pressure homogenization, the use of nano-particles increased mean droplet sizes. This resulted in noted (p < 0.05) differences in stability with emulsions stabilized by LF nano-particles and alginate showing poorest stability. Concomitantly, the use of i-carrageenan and LF nano-particles yielded emulsions with the most reduced creaming (<1 μm/s), even compared to emulsions stabilized by native LF. Interestingly, the use of alginate and i-carrageenan with LF nano-particles also altered emulsion stability to artificial saliva and modulated emulsion behavior under gastric conditions, which was linked to reduced rate of LF gastric proteolysis. Overall, this work establishes a new possibility to incorporate LF in emulsions and demonstrates how LF nano-particles could be harnessed to modulate emulsion destabilization and breakdown in the mouth and stomach.