Design Rules for Laser‐Treated Icephobic Metallic Surfaces for Aeronautic Applications

Ice accretion on external aircraft surfaces due to the impact of supercooled water droplets can negatively affect the aerodynamic performance and reduce the operational capability and, therefore, must be prevented. Icephobic coatings capable of reducing the adhesion strength of ice to a surface represent a promising technology to support thermal or mechanical ice protection systems. Icephobicity is similar to hydrophobicity in several aspects and superhydrophobic surfaces embody a straightforward solution to the ice adhesion problem. Short/ultrashort pulsed laser surface treatments are proposed as a viable technology to generate superhydrophobic properties on metallic surfaces. However, it has not yet been verified whether such surfaces are generally icephobic under representative icing conditions. This study investigates the ice adhesion strength on Ti6Al4V, an alloy commonly used for aerospace components, textured by means of direct laser writing, direct laser interference patterning, and laser-induced periodic surface structures laser sources with pulse durations ranging from nano- to femtosecond regimes. A clear relation between the spatial period, the surface microstructure depth, and the ice adhesion strength under different icing conditions is investigated. From these observations, a set of design rules can be defined for superhydrophobic surfaces that are icephobic, too

LLNL Middle East and North Africa research database

The Lawrence Livermore National Laboratory (LLNL) Comprehensive Nuclear-Test-Ban Treaty Research and Development (CTBT R and D) program has made significant progress populating a comprehensive seismic research database (RDB) for seismic events and derived research products in the Middle East and North Africa (MENA). Our original ME/NA study region has enlarged and is now defined as an area including the Middle East, Africa, Europe, Southwest Asia, the Former Soviet Union and the Scandinavian/Arctic region. The LLNL RDB will facilitate calibration of all International Monitoring System (IMS) stations (primary and auxiliary) or their surrogates (if not yet installed) as well as a variety of gamma stations. The RDB provides not only a coherent framework in which to store and organize large volumes of collected seismic waveforms and associated event parameter information, but also provides an efficient data processing/research environment for deriving location and discrimination correction sur faces and capabilities. In order to accommodate large volumes of data from many sources with diverse formats the RDB is designed to be flexible and extensible in addition to maintaining detailed quality control information and associated metadata. Station parameters, instrument responses, phase pick information, and event bulletins were compiled and made available through the RDB. For seismic events in the MENA region occurring between 1976 and 1999, we have systematically assembled, quality checked and organized event waveforms; continuous seismic data from 1990 to present are archived for many stations. Currently, over 11,400 seismic events and 1.2 million waveforms are maintained in the RDB and made readily available to researchers. In addition to open sources of seismic data, we have established collaborative relationships with several ME/NA countries that have yielded additional ground truth and broadband waveform data essential for regional calibration and capability studies. Additional data and ground truth from other countries are also currently being sought. Research results, along with descriptive metadata are stored and organized within the LLNL RDB and prepared for delivery and integration into the Department of Energy (DOE) Knowledge Base (KB). Deliverables consist of primary data products (raw materials for calibration) and derived products (distilled from the organized raw seismological data). By combining travel-time observations, event characterization studies, and regional wave-propagation studies of the LLNL CTBT research team for ground truth events and regional events, we have assembled a library of ground truth information, event location correction surfaces, tomographic models and mine explosion histories required to support the ME/NA regionalization program. Corrections and parameters distilled from the LLNL RDB provide needed contributions to the KB for the MENA region and will enable the United States National Data Center (NDC) to effectively verify CTBT compliance. The LLNL portion of the DOE KB supports critical NDC pipeline functions in detection, location, feature extraction, discrimination, and analyst review in the Middle East and North Africa

Enhancing Seismic Calibration Research Through Software Automation and Scientific Information Management

The National Nuclear Security Administration (NNSA) Ground-Based Nuclear Explosion Monitoring Research and Engineering (GNEM R&E) Program at LLNL has made significant progress enhancing the process of deriving seismic calibrations and performing scientific integration, analysis, and information management with software automation tools. Several achievements in schema design, data visualization, synthesis, and analysis were completed this year. Our tool efforts address the problematic issues of very large datasets and varied formats encountered during seismic calibration research. As data volumes have increased, scientific information management issues such as data quality assessment, ontology mapping, and metadata collection that are essential for production and validation of derived calibrations have negatively impacted researchers abilities to produce products. New information management and analysis tools have resulted in demonstrated gains in efficiency of producing scientific data products and improved accuracy of derived seismic calibrations. Significant software engineering and development efforts have produced an object-oriented framework that provides database centric coordination between scientific tools, users, and data. Nearly a half billion parameters, signals, measurements, and metadata entries are all stored in a relational database accessed by an extensive object-oriented multi-technology software framework that includes elements of stored procedures, real-time transactional database triggers and constraints, as well as coupled Java and C++ software libraries to handle the information interchange and validation requirements. Significant resources were applied to schema design to enable recording of processing flow and metadata. A core capability is the ability to rapidly select and present subsets of related signals and measurements to the researchers for analysis and distillation both visually (JAVA GUI client applications) and in batch mode (instantiation of multi-threaded applications on clusters of processors). Development of efficient data exploitation methods has become increasingly important throughout academic and government seismic research communities to address multi-disciplinary large scale initiatives. Effective frameworks must also simultaneously provide the researcher with robust measurement and analysis tools that can handle and extract groups of events effectively and isolate the researcher from the now onerous task of database management and metadata collection necessary for validation and error analysis. Sufficient information management robustness is required to avoid loss of metadata that would lead to incorrect calibration results in addition to increasing the data management burden. Our specific automation methodology and tools improve the researchers ability to assemble quality-controlled research products for delivery into the NNSA Knowledge Base (KB). The software and scientific automation tasks also provide the robust foundation upon which synergistic and efficient development of, GNEM R&E Program, seismic calibration research may be built

Parametric study of EEG sensitivity to phase noise during face processing

<b>Background: </b> The present paper examines the visual processing speed of complex objects, here faces, by mapping the relationship between object physical properties and single-trial brain responses. Measuring visual processing speed is challenging because uncontrolled physical differences that co-vary with object categories might affect brain measurements, thus biasing our speed estimates. Recently, we demonstrated that early event-related potential (ERP) differences between faces and objects are preserved even when images differ only in phase information, and amplitude spectra are equated across image categories. Here, we use a parametric design to study how early ERP to faces are shaped by phase information. Subjects performed a two-alternative force choice discrimination between two faces (Experiment 1) or textures (two control experiments). All stimuli had the same amplitude spectrum and were presented at 11 phase noise levels, varying from 0% to 100% in 10% increments, using a linear phase interpolation technique. Single-trial ERP data from each subject were analysed using a multiple linear regression model. <b>Results: </b> Our results show that sensitivity to phase noise in faces emerges progressively in a short time window between the P1 and the N170 ERP visual components. The sensitivity to phase noise starts at about 120–130 ms after stimulus onset and continues for another 25–40 ms. This result was robust both within and across subjects. A control experiment using pink noise textures, which had the same second-order statistics as the faces used in Experiment 1, demonstrated that the sensitivity to phase noise observed for faces cannot be explained by the presence of global image structure alone. A second control experiment used wavelet textures that were matched to the face stimuli in terms of second- and higher-order image statistics. Results from this experiment suggest that higher-order statistics of faces are necessary but not sufficient to obtain the sensitivity to phase noise function observed in response to faces. <b>Conclusion: </b> Our results constitute the first quantitative assessment of the time course of phase information processing by the human visual brain. We interpret our results in a framework that focuses on image statistics and single-trial analyses

SPE 1 Data Quicklook report

Abstract not provide

Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach

Background: In this study, we quantified age-related changes in the time-course of face processing by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our approach does not rely on peak measurements and can provide a more sensitive measure of processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded discrimination task between two faces. The phase spectrum of these faces was manipulated parametrically to create pictures that ranged between pure noise (0% phase information) and the undistorted signal (100% phase information), with five intermediate steps. Results: Behavioural 75% correct thresholds were on average lower, and maximum accuracy was higher, in younger than older observers. ERPs from each subject were entered into a single-trial general linear regression model to identify variations in neural activity statistically associated with changes in image structure. The earliest age-related ERP differences occurred in the time window of the N170. Older observers had a significantly stronger N170 in response to noise, but this age difference decreased with increasing phase information. Overall, manipulating image phase information had a greater effect on ERPs from younger observers, which was quantified using a hierarchical modelling approach. Importantly, visual activity was modulated by the same stimulus parameters in younger and older subjects. The fit of the model, indexed by R2, was computed at multiple post-stimulus time points. The time-course of the R2 function showed a significantly slower processing in older observers starting around 120 ms after stimulus onset. This age-related delay increased over time to reach a maximum around 190 ms, at which latency younger observers had around 50 ms time lead over older observers. Conclusion: Using a component-free ERP analysis that provides a precise timing of the visual system sensitivity to image structure, the current study demonstrates that older observers accumulate face information more slowly than younger subjects. Additionally, the N170 appears to be less face-sensitive in older observers

SPE2 Far-field Seismic Data Quicklook

The purpose of this report is to provide a brief overview of the far-field seismic data collected by the array of instruments (Figures 1 and 2) deployed by the Source Physics experiment for shots 1 (roughly 100 kg TNT equivalent at a depth of 60 m) and shot 2, (roughly 2000 kg TNT equivalent at a depth of 45 m). 'Far-field' is taken to refer to instruments in the zone of purely elastic response at distances of 100 m or greater. The primary focus is data from the main instrument array and hence data from other groups is not considered. Infrasound data is not addressed nor any remote sensing data. Data processing was done at LLNL in parallel with the effort at UNR. Raw reftek data was sent via hard disk from NsTec. Reftek data was converted to SEGY and then to SAC format. Data files were renamed according to station and channel information. Reftek logs were reviewed. These data have been reviewed for consistency with the UNR data on the server. The primary goal was quality check and a summary is provided in Tables 1 and 2