Stability relationship for water droplet crystallization with the NASA Lewis icing spray

In order to produce small droplets for icing cloud simulation, high pressure air atomizing nozzles are used. For certain icing testing applications, median drop sizes as small as 5 mm are needed, which require air atomizing pressures greater than 3000 kPa. Isentropic expansion of the ambient temperature atomizing air to atmospheric pressure can result in air stream temperatures of -160 C which results in ice crystals forming in the cloud. To avoid such low temperatures, it is necessary to heat the air and water to high initial temperatures. An icing spray research program was conducted to map the temperatures below which ice crystals form. A soot slide technique was used to determine the presence of crystals in the spray

Gaming on the edge: using seams in ubicomp games

Outdoor multi-player games are an increasingly popular application area for ubiquitous computing, supporting experimentation both with new technologies and new user experiences. This paper presents an outdoor ubicomp game that exploits the gaps or seams that exist in complex computer systems. Treasure is designed so that players move in and out of areas of wireless network coverage, taking advantage not only of the connectivity within a wireless ‘hotspot’ but of the lack of connectivity outside it. More broadly, this paper discusses how the notion of seamful design can be a source of design ideas for ubicomp games

Classification with Asymmetric Label Noise: Consistency and Maximal Denoising

In many real-world classification problems, the labels of training examples are randomly corrupted. Most previous theoretical work on classification with label noise assumes that the two classes are separable, that the label noise is independent of the true class label, or that the noise proportions for each class are known. In this work, we give conditions that are necessary and sufficient for the true class-conditional distributions to be identifiable. These conditions are weaker than those analyzed previously, and allow for the classes to be nonseparable and the noise levels to be asymmetric and unknown. The conditions essentially state that a majority of the observed labels are correct and that the true class-conditional distributions are "mutually irreducible," a concept we introduce that limits the similarity of the two distributions. For any label noise problem, there is a unique pair of true class-conditional distributions satisfying the proposed conditions, and we argue that this pair corresponds in a certain sense to maximal denoising of the observed distributions. Our results are facilitated by a connection to "mixture proportion estimation," which is the problem of estimating the maximal proportion of one distribution that is present in another. We establish a novel rate of convergence result for mixture proportion estimation, and apply this to obtain consistency of a discrimination rule based on surrogate loss minimization. Experimental results on benchmark data and a nuclear particle classification problem demonstrate the efficacy of our approach

The 2014 International Planning Competition: Progress and Trends

We review the 2014 International Planning Competition (IPC-2014), the eighth in a series of competitions starting in 1998. IPC-2014 was held in three separate parts to assess state-of-the-art in three prominent areas of planning research: the deterministic (classical) part (IPCD), the learning part (IPCL), and the probabilistic part (IPPC). Each part evaluated planning systems in ways that pushed the edge of existing planner performance by introducing new challenges, novel tasks, or both. The competition surpassed again the number of competitors than its predecessor, highlighting the competition’s central role in shaping the landscape of ongoing developments in evaluating planning systems

The Contribution of Functional Brain Networks and Oscillations to the Development of Cognitive Control

Adolescence is a qualitatively unique period of development when cognitive control abilities are available but are unreliably engaged, which can lead to risk-taking behavior impacting survival. The specific neural mechanisms contributing to the maturation of cognitive control remain poorly understood. To address this issue, we employed functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) to study brain networks and oscillations underlying cognitive control development in both the resting state and during a cognitive flexibility task. In the first study, we found that the organization of brain networks was established prior to adolescence. However, a network of brain regions anchored in the anterior cingulate cortex (ACC) and anterior insula (aIns) significantly increased its influence over other brain networks via increased network integration during the resting state, resulting in faster correct responses on a cognitive control task. In the second study, we leveraged increased temporal resolution using MEG to further probe resting state connectivity changes with age. We found similar medial prefrontal regions became less coupled in their interactions with the rest of the brain, specifically in the theta band (5-9 Hz oscillations), and were related to developmental decreases in impulsivity. As such, these results suggest there are developmental increases in the flexibility of resting state connectivity, which may afford less effortful instantiation of cognitive control. The third study directly tested age-related changes in brain oscillations during a cognitive flexibility paradigm. We found evidence of strong induction of theta band oscillations in the ACC when task switching that scaled positively with average reaction time. Similar to our resting state MEG findings, we found that the prominence of ACC theta band rhythms decreased with development, suggesting that during cognitive flexibility, adolescents need to engage greater cognitive control to switch between cognitive demands compared to adults. Taken together, these results inform a model of adolescent development such that the specialization of medial prefrontal systems plays a primary role in developmental improvements in cognitive control as they strengthen their integration with other networks. Increased network integration affords these regions the ability to more flexibly engage other brain regions, supporting the maturation of cognitive control

High selectivity epoxidation of ethylene in chemical looping setup

We describe the remarkable performance of a new catalyst for the chemical looping (CL-) epoxidation of ethylene, performed at atmospheric pressure and without any promoters added to either the catalyst or the feed gas. To undertake the CL-epoxidation of ethylene, silver was used as the catalyst, supported on either the perovskite SrFeO3 or Ce-modified SrFeO3. Here, the oxygen for the reaction is supplied to the silver catalyst from the active solid support, not from the gas stream. When the support has been reduced and depleted of oxygen, it is regenerated in a separate step with air, which makes the process cyclic and closes a chemical loop. Thus, there is no need to co-feed gaseous oxygen along with the ethylene feed, an important improvement in safety. Two methods were used to synthesise Ce-modified materials, employing either (i) the mechanical mixing of powdered CeO2 and the solid precursors of the perovskite, or (ii) the impregnation of a solution of cerium nitrate into solid particles of SrFeO3. In both cases, the materials were calcined to produce a mixture of CeO2 and SrFeO3. Both CeO2-SrFeO3 materials surpassed the unmodified SrFeO3 for CL-epoxidation. For the CeO2-SrFeO3 prepared by mechanical mixing, the production of ethylene oxide was stable over 15 cycles, giving 60% selectivity at 10% conversion of C2H4. In contrast, the material prepared by impregnation gave up to 85% selectivity but only in the first cycle of reduction, with the performance degrading over subsequent cycles. The reported results are better than the 50% selectivity achieved for the classical epoxidation using pure silver as the catalyst and feeds of gaseous ethylene and oxygen, without reaction promoters