Optimization of structures on the basis of fracture mechanics and reliability criteria

Systematic summary of factors which are involved in optimization of given structural configuration is part of report resulting from study of analysis of objective function. Predicted reliability of performance of finished structure is sharply dependent upon results of coupon tests. Optimization analysis developed by study also involves expected cost of proof testing

Analytical procedure for estimating reliability of randomly excited structures

Analysis considers statistical variation of material strength and interactions between catastrophic and failure fatigue modes. Procedure employs concepts of fracture mechanics and extreme point processes associated with stationary narrow-band random vibrations

Optimum pressure vessel design based on fracture mechanics and reliability criteria

Optimization design methods for spacecraft structural systems and subsystem

Does binding of synesthetic color to the evoking grapheme require attention?

The official published version can be accessed from the link below.The neural mechanisms involved in binding features such as shape and color are a matter of some debate. Does accurate binding rely on spatial attention functions of the parietal lobe or can it occur without attentional input? One extraordinary phenomenon that may shed light on this question is that of chromatic-graphemic synesthesia, a rare condition in which letter shapes evoke color perceptions. A popular suggestion is that synesthesia results from cross-activation between different functional regions (e.g., between shape and color areas of the ventral pathway). Under such conditions binding may not require parietal involvement and could occur preattentively. We tested this hypothesis in two synesthetes who perceived grayscale letters and digits in color. We found no evidence for preattentive binding using a visual search paradigm in which the target was a synesthetic inducer. In another experiment involving color judgments, we show that the congruency of target color and the synesthetic color of irrelevant digits modulates performance more when the digits are included within the attended region of space. We propose that the mechanisms giving rise to this type of synesthesia appear to follow at least some principles of normal binding, and even synesthetic binding seems to require attention.This work has been supported by a Veterans Administration Senior Research Career Scientist Award and NINDS grant #MH62331 to LCR and the Elizabeth Roboz Einstein fellowship in Neuroscience and Human Development to NS

Optimization of space antenna structures

Spacecraft antenna concepts, structural types, and material

Evidence for Interlayer Electronic Coupling in Multilayer Epitaxial Graphene from Polarization Dependent Coherently Controlled Photocurrent Generation

Most experimental studies to date of multilayer epitaxial graphene on C-face SiC have indicated that the electronic states of different layers are decoupled as a consequence of rotational stacking. We have measured the third order nonlinear tensor in epitaxial graphene as a novel approach to probe interlayer electronic coupling, by studying THz emission from coherently controlled photocurrents as a function of the optical pump and THz beam polarizations. We find that the polarization dependence of the coherently controlled THz emission expected from perfectly uncoupled layers, i.e. a single graphene sheet, is not observed. We hypothesize that the observed angular dependence arises from weak coupling between the layers; a model calculation of the angular dependence treating the multilayer structure as a stack of independent bilayers with variable interlayer coupling qualitatively reproduces the polarization dependence, providing evidence for coupling.Comment: submitted to Nano Letter

Computationally Efficient Reinforcement Learning: Targeted Exploration leveraging simple Rules

Reinforcement Learning (RL) generally suffers from poor sample complexity, mostly due to the need to exhaustively explore the state-action space to find well-performing policies. On the other hand, we postulate that expert knowledge of the system often allows us to design simple rules we expect good policies to follow at all times. In this work, we hence propose a simple yet effective modification of continuous actor-critic frameworks to incorporate such rules and avoid regions of the state-action space that are known to be suboptimal, thereby significantly accelerating the convergence of RL agents. Concretely, we saturate the actions chosen by the agent if they do not comply with our intuition and, critically, modify the gradient update step of the policy to ensure the learning process is not affected by the saturation step. On a room temperature control case study, it allows agents to converge to well-performing policies up to 6-7x faster than classical agents without computational overhead and while retaining good final performance.Comment: Submitted to CDC 202

Microscopic correlation between chemical and electronic states in epitaxial graphene on SiC(000-1)

We present energy filtered electron emission spectromicroscopy with spatial and wave-vector resolution on few layer epitaxial graphene on SiC$(000-1) grown by furnace annealing. Low energy electron microscopy shows that more than 80% of the sample is covered by 2-3 graphene layers. C1s spectromicroscopy provides an independent measurement of the graphene thickness distribution map. The work function, measured by photoelectron emission microscopy (PEEM), varies across the surface from 4.34 to 4.50eV according to both the graphene thickness and the graphene-SiC interface chemical state. At least two SiC surface chemical states (i.e., two different SiC surface structures) are present at the graphene/SiC interface. Charge transfer occurs at each graphene/SiC interface. K-space PEEM gives 3D maps of the k_|| pi - pi* band dispersion in micron scale regions show that the Dirac point shifts as a function of graphene thickness. Novel Bragg diffraction of the Dirac cones via the superlattice formed by the commensurately rotated graphene sheets is observed. The experiments underline the importance of lateral and spectroscopic resolution on the scale of future electronic devices in order to precisely characterize the transport properties and band alignments

‘It will be hard because I will have to learn lots of English’: Experiences of education for children newly arrived in Australia

“This is an Accepted Manuscript of an article published by Taylor & Francis in [International Journal of Qualitative Studies in Education,] on [01 Jan 2015], available online: http:// www.tandfonline.com/10.1080/09518398.2015.1023232.”Educational experiences during childhood are critically important for development, but migrant children often experience unique challenges. To ameliorate these, extra training in English language - such as provided by the Intensive English language program in South Australia (IELP) - is frequently offered to children taking on English as an additional language (EAL). The present study aimed to examine the experience of transition into mainstream classes for children in the IELP, particularly in relation to their overall wellbeing. As such, the study utilised interviews conducted with newly arrived children in Australia aged five to 13 who were enrolled in an IELP, with interviews conducted both pre and post transition into mainstream primary school classes. The findings indicate that most children felt anxious prior to transition, especially regarding speaking English, but were less concerned about this once entering their new class. Making friends was considered to be difficult, but easier when there were children with whom they were familiar from other contexts, or if there was another child in the class with a shared cultural or linguistic background