160 research outputs found

    A Generic Multibody Parachute Simulation Model

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    Flight simulation of dynamic atmospheric vehicles with parachute systems is a complex task that is not easily modeled in many simulation frameworks. In the past, the performance of vehicles with parachutes was analyzed by simulations dedicated to parachute operations and were generally not used for any other portion of the vehicle flight trajectory. This approach required multiple simulation resources to completely analyze the performance of the vehicle. Recently, improved software engineering practices and increased computational power have allowed a single simulation to model the entire flight profile of a vehicle employing a parachute

    Generic Spacecraft Model for Real-Time Simulation

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    Generic Spacecraft is the name of an evolving library of software that provides for simulation of a generic spacecraft that can orbit the Earth and land on the Moon (and, eventually, on Mars). This library is incorporated into the Langley Standard Realtime Simulation in C++ (LaSRS++) software framework. The generic-spacecraft simulation serves as a test bed for modeling spacecraft dynamics, propulsion, control systems, guidance, and displays. The Generic Spacecraft library supplements the LaSRS++ framework with an interface that facilitates the connection of new models into the LaSRS++ simulation by eliminating what would otherwise be the necessity of writing additional C++ classes to record data from the models and code to display values on graphical user interfaces (GUIs): The library includes routines for integrating new models into the LaSRS++ framework, identifying model inputs and outputs with full descriptions and units identified, recording data, and automatically generating graphical user interfaces (GUIs). The library is designed to be used in a manner similar to that of LaSRS++ software components for simulating vehicles other than the generic spacecraft. The user specifies (1) a spacecraft and individual models to be constructed and (2) connections between individual model inputs and outputs

    16.3 Are Visual Motion Perception and Detection of Animacy Critical to Higher-Order Social Cognitive Function in Schizophrenia?

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    Background The observation that individuals with schizophrenia tend to misinterpret subtle social cues is often attributed to deficit in Theory of Mind (ToM). While ToM is commonly assessed using videos portraying interaction between actors, recent work in vision science shows that stimuli with no innate animate features can also convey similar social information through motion alone. These simplified stimuli are advantageous for experimental purposes and may provide further insights into perceptual mechanisms supporting social cognitive function. The Social Attribution Task-Multiple Choice (SAT-MC), based on the classic Hieder and Simmel (1944) stimuli, tells a story using three geometric shapes moving about a centrally fixed figure, followed by questions about what the viewer observed. Although there are no explicit social cues, viewers typically detect actions suggestive of relationships between objects, their intentions, and emotions. This talk will present findings from three studies examining psychometric, functional, and neurophysiological aspects on SAT -MC performance in schizophrenia. Methods Study 1 examined psychometric properties of two forms of the SAT-MC in comparison to video-based social cognitive tests using human actors in 32 schizophrenia (SZ) and 30 substance use disorder (SUD) participants. Study 2 examined functional relationships of the SAT-MC and affect recognition (BLERT) performance across neurocognitive, metacognitive, ToM, and symptom domains in 72 adults with SZ. Study 3 is an in-progress investigation of neurophysiological mechanisms of social cognition using test versions adapted for EEG recording. Chronic SZ, clinical high-risk (CHR), and healthy age-matched community samples are being collected. Results SZ scored significantly lower than SUD on two versions of the SAT-MC, each classifying ~60% of SZ as impaired, compared with ~30% of SUD. The two SAT-MC forms demonstrated good test-retest and parallel form reliability, minimal practice effect, high internal consistency, similar patterns of correlation with social cognitive test performance, and compared favorably to social cognitive tests across psychometric features. When examining functional correlates of SAT -MC performance, impairment is found to co-occur with deficits in affect recognition in the majority of cases but relates uniquely to reductions in verbal memory and emotional intelligence measures. Finally, a preliminary analysis (n=8 SZ, n=2 CHR) of EEG collected during SAT-MC video presentation finds significant correlations (r=.66-.72) between occipito-parietal gamma desynchronization and task performance. Additional analyses find task-related EEG during SAT to be predictive of affect recognition (BLERT) and ToM (TASIT) performance, with correlates including alpha desynchronization in frontal, occipital, and temporal regions, and synchronization of temporal theta and occipital gamma (all r > .5). Conclusions SAT-MC performance is found to be reliable using different stimuli, related to affect recognition and ToM in three independent samples, and shows high diagnostic specificity in classifying SZ against a SUD sample. Functional correlates also involve encoding and emotional intelligence abilities tested outside the visual modality. Analysis of neural oscillatory activity related SAT-MC performance to visual and attention processes, as well as engagement of a broader social cognitive network applied to affect recognition and ToM tasks. Impairment in visual motion processing appears integral to schizophrenia pathophysiology and a critical factor influencing social cognitive abilities attributed to higher-order ToM ability

    Techno-economic analysis of decentralized biomass processing depots

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    AbstractDecentralized biomass processing facilities, known as biomass depots, may be necessary to achieve feedstock cost, quantity, and quality required to grow the future U.S. bioeconomy. In this paper, we assess three distinct depot configurations for technical difference and economic performance. The depot designs were chosen to compare and contrast a suite of capabilities that a depot could perform ranging from conventional pelleting to sophisticated pretreatment technologies. Our economic analyses indicate that depot processing costs are likely to range from ∼US30toUS30 to US63 per dry metric tonne (Mg), depending upon the specific technology implemented and the energy consumption for processing equipment such as grinders and dryers. We conclude that the benefits of integrating depots into the overall biomass feedstock supply chain will outweigh depot processing costs and that incorporation of this technology should be aggressively pursued

    Pressure-Driven Valence Increase and Metallization in Kondo Insulator Ce3_3Bi4_4Pt3_3

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    We report the results of high pressure x-ray diffraction, x-ray absorption, and electrical transport measurements of Kondo insulator Ce3_3Bi4_4Pt3_3 up to 42 GPa, the highest pressure reached in the study of any Ce-based KI. We observe a smooth decrease in volume and movement toward intermediate Ce valence with pressure, both of which point to increased electron correlations. Despite this, temperature-dependent resistance data show the suppression of the interaction-driven ambient pressure insulating ground state. We also discuss potential ramifications of these results for the predicted topological KI state.Comment: 8 pages, 5 figure

    Hybrid Airship Multi-Role (HAMR) Anti-Submarine Warfare (ASW) mission capability

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    The Hybrid Airship Multi-Role (HAMR) Anti-Submarine Warfare (ASW) Mission Module project applies established systems engineering principles and processes to the design of an ASW payload module that examines the capability of the HAMR to perform persistent ASW mission support. Critical system functions and objectives are identified and are assigned appropriate quantitative metrics. Additionally, three alternative architectures are generated and evaluated using the appropriate metrics based on results from modeling using Naval Systems Simulation (NSS). Manning is considered as a key stakeholder parameter and is included as an evaluation concern. The alternatives are also compared through the examination of life cycle costs. The recommendation to the stakeholders based on the research and results is an unmanned ASW sensor platform that uses other ASW assets for prosecution.http://archive.org/details/hybridairshipmul109456935N

    L-Edge Spectroscopy of Dilute, Radiation-Sensitive Systems Using a Transition-Edge-Sensor Array

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    We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by conventional grating-based spectrometers. These results show that soft X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.Comment: 19 pages, 4 figure

    RCT of Web-based Personalized Normative Feedback for College Drinking Prevention: Are Typical Student Norms Good Enough?

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    Objectives Personalized normative feedback (PNF) interventions are generally effective at correcting normative misperceptions and reducing risky alcohol consumption among college students. However, research has yet to establish what level of reference group specificity is most efficacious in delivering PNF. This study compared the efficacy of a web-based PNF intervention employing eight increasingly-specific reference groups against a Web-BASICS intervention and a repeated-assessment control in reducing risky drinking and associated consequences. Method Participants were 1663 heavy drinking Caucasian and Asian undergraduates at two universities. The referent for web-based PNF was either the typical same-campus student, or a same-campus student at one (either gender, race, or Greek-affiliation), or a combination of two (e.g., gender and race), or all three levels of specificity (i.e., gender, race, and Greek-affiliation). Hypotheses were tested using quasi-Poisson generalized linear models fit by generalized estimating equations. Results The PNF intervention participants showed modest reductions in all four outcomes (average total drinks, peak drinking, drinking days, and drinking consequences) compared to control participants. No significant differences in drinking outcomes were found between the PNF group as a whole and the Web-BASICS group. Among the eight PNF conditions, participants receiving typical student PNF demonstrated greater reductions in all four outcomes compared to those receiving PNF for more specific reference groups. Perceived drinking norms and discrepancies between individual behavior and actual norms mediated the efficacy of the intervention. Conclusions Findings suggest a web-based PNF intervention using the typical student referent offers a parsimonious approach to reducing problematic alcohol use outcomes among college students

    RCT of web-based personalized normative feedback for college drinking prevention: Are typical student norms good enough?

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    Objectives: Personalized normative feedback (PNF) interventions are generally effective at correcting normative misperceptions and reducing risky alcohol consumption among college students. However, research has yet to establish what level of reference group specificity is most efficacious in delivering PNF. This study compared the efficacy of a web-based PNF intervention employing eight increasingly-specific reference groups against a Web-BASICS intervention and a repeated-assessment control in reducing risky drinking and associated consequences. Method: Participants were 1663 heavy drinking Caucasian and Asian undergraduates at two universities. The referent for web-based PNF was either the typical same-campus student, or a same-campus student at one (either gender, race, or Greek-affiliation), or a combination of two (e.g., gender and race), or all three levels of specificity (i.e., gender, race, and Greek-affiliation). Hypotheses were tested using quasi-Poisson generalized linear models fit by generalized estimating equations. Results: The PNF intervention participants showed modest reductions in all four outcomes (average total drinks, peak drinking, drinking days, and drinking consequences) compared to control participants. No significant differences in drinking outcomes were found between the PNF group as a whole and the Web-BASICS group. Among the eight PNF conditions, participants receiving typical student PNF demonstrated greater reductions in all four outcomes compared to those receiving PNF for more specific reference groups. Perceived drinking norms and discrepancies between individual behavior and actual norms mediated the efficacy of the intervention. Conclusions: Findings suggest a web-based PNF intervention using the typical student referent offers a parsimonious approach to reducing problematic alcohol use outcomes among college students

    Cyclical browning in a subtropical lake inferred from diatom records

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    Changing climate and land use activity are altering inputs of colored dissolved organic carbon (cDOC) into lakes. Increased cDOC reduces water transparency (browning) and changes lake physicochemistry, with biological consequences. Identifying the drivers and effects of changing cDOC inputs is critical for mitigating the consequences of climate change on lake ecosystems through adaptive watershed management. This study focused on determining the drivers of lake browning by evaluating shifts in diatom assemblages in subtropical, oligotrophic Lake Annie (FL, United States), which is known to experience climate-driven oscillations in transparency associated with watershed inputs of cDOC. We combined long-term limnological monitoring data and paleolimnological techniques to determine how diatoms respond to changes in cDOC and to infer past cDOC fluctuations relative to records of past climate and land use changes in the watershed. Diatom assemblage composition in a 14-year phytoplankton dataset was strongly correlated with cDOC-driven transparency fluctuations. Likewise, diatom assemblages in the upper 35 cm of the sediment core, which corresponded to a 35-year lake monitoring record, were also strongly related to past water transparency, yielding a strong transfer function (paleo model, R2 = 0.72). When the model was applied to the diatom record from a 166-cm sediment core, diatom-inferred transparency and rates of nutrient input showed that localized ditching in the 1930s enhanced the effect of climate oscillations on water transparency, intensifying cyclical browning thereafter. Integration of long-term monitoring and paleoecological data provided valuable insights into the history of the aquatic ecosystem, enabling implementation of adaptive management strategies to contend with a changing climate
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