A eutectic salt high temperature phase change material: Thermal stability and corrosion of SS316 with respect to thermal cycling

Thermal energy storage (TES) is a critical component in a concentrated solar power (CSP) plant since it is able to provide dispatchability and increase the capacity factor of the plant. Recently the Brayton power cycle using supercritical carbon dioxide (s-CO2) has attracted considerable attention as it allows a higher thermal to electric power conversion efficiency compared to the conventional Rankine cycle using subcritical steam. However, no commercial TES has yet been developed for integration with a s-CO2 based plant. One reason is the lack of a suitable storage material. This work explores the use of a eutectic NaCl-Na2CO3 salt as a reliable high temperature phase change material (PCM). The PCM has been thermally cycled up to 1000 times. Its thermophysical properties have been measured before and after it has been subjected to the thermal cycling and its corrosion behavior has been investigated. This eutectic salt shows good thermal stability without degradation after cycling 1000 times between 600 and 650 °C. The corrosion rate on stainless steel 316 (SS316) increases linearly up to 350 cycles, and thereafter it stabilizes at 70 mg/cm2

Electrophysiological Correlates of Visual Singleton Detection

Identifying a fixed-feature singleton that pops out from an otherwise uniform array of distractors elicits an event-related potential (ERP) component called the N2pc over the posterior scalp. The N2pc has been used to track attention with millisecond accuracy, inform theories of visual selection, and test for specific attention deficits in clinical populations, yet it is still unclear what neuro-cognitive process gives rise to the component. One hypothesis is that the N2pc reflects a spatial filtering process that suppresses irrelevant distractors. In support of this hypothesis, Luck and Hillyard (1994) showed that the N2pc is eliminated when the features of the target and distractors switch unpredictably across trials so that participants cannot prepare to filter out irrelevant items. The present study aimed to replicate Luck and Hillyard’s singleton detection experiment, but with modifications to enhance the N2pc signal and to gain statistical power. We show that orientation singletons do, in fact, elicit the N2pc as well as an earlier-onsetting and longer-lasting singleton detection positivity (SDP) over the occipital scalp when the target and distractor orientations swap randomly across trials. We conclude that spatial filtering might not play a major role in the generation of the N2pc and that the selection processes required to search for fixed-feature targets (in feature-search mode) are also engaged in the detection of variable-feature singletons (in singleton-detection mode)

Isolating the Neural Substrates of Visually Guided Attention Orienting in Humans

The neural processes that enable healthy humans to orient attention to sudden visual events are poorly understood because they are tightly intertwined with purely sensory processes. Here we isolated visually guided orienting activity from sensory activity using event-related potentials (ERPs). By recording ERPs to a lateral stimulus and comparing waveforms obtained under conditions of attention and inattention, we identified an early positive deflection over the ipsilateral visual cortex that was associated with the covert orienting of visual attention to the stimulus. Across five experiments with male and female adults participants, this ipsilateral visual orienting activity (VOA) could be distinguished from purely sensory-evoked activity and from other top-down spatial attention effects. The VOA was linked with behavioral measures of orienting, being significantly larger when the stimulus was detected rapidly than when it was detected more slowly, and its presence was independent of saccadic eye movements towards the targets. The VOA appears to be a specific neural index of the visually guided orienting of attention to a stimulus that appears abruptly in an otherwise uncluttered visual field

Corrosion of AISI316 as containment material for latent heat thermal energy storage systems based on carbonates

Considerable effort has been devoted to the characterization of thermal properties of the different types of materials that can be used as thermal energy storage (TES) media, but scarce literature exists concerning the materials to manufacture the tanks that can be used to contain these storage media. One of the main concerns when selecting the most suitable material for these tanks is its resistance to corrosion due to molten salts that constitute the TES system. Dynamic gravimetric analysis is a newly proposed method for the study of corrosion on metals, which optimizes the standard procedure described by ASTM G1-03. The new technique avoids the direct handling of samples, so more accurate values can be obtained. In this work, the resistance to corrosion of AISI 316 stainless steel samples in contact with commercial grade molten salts of the Li2CO3-Na2CO3-K2CO3 system, at 600 °C for different exposure times, has been determined by using this new methodology. The results show that the initial corrosion rate is lower at higher amounts of lithium carbonate present in the molten salts mixture

Protecting the skies: GNSS-less aircraft navigation with terrestrial cellular signals of opportunity

This paper shows how to protect our skies from harmful radio frequency interference (RFI) to global navigation satellite system (GNSS) signals, by offering terrestrial cellular signals of opportunity (SOPs) as a viable aircraft navigation system backup. An extensive flight campaign was conducted by the Autonomous Systems Perception, Intelligence, and Navigation (ASPIN) Laboratory in collaboration with the United States Air Force (USAF) to study the potential of cellular SOPs for high-altitude aircraft navigation. A multitude of flight trajectories and altitudes were exercised in the flight campaign in two different regions in Southern California, USA: (i) rural and (ii) semi-urban. Samples of the ambient downlink cellular SOPs were recorded, which were fed to ASPIN Laboratory's MATRIX (Multichannel Adaptive TRansceiver Information eXtractor) software-defined receiver (SDR), which produced carrier phase measurements from these samples. These measurements were fused with altimeter data via an extended Kalman filter (EKF) to estimate the aircraft's trajectory. This paper shows for the first time that at altitudes as high as about 11,000 ft above ground level (AGL), more than 100 cellular long-term evolution (LTE) eNodeBs can be reliable tracked, many of which were more than 100 km away, with carrier-to-noise ratio (C/N0) exceeding 40 dB-Hz. The paper shows pseudorange and Doppler tracking results from cellular eNodeBs along with the C/N0 and number of tracked eNodeBs over the two regions, while performing ascending, descending, and grid maneuvers. In addition, the paper shows navigation results in the semi-urban and rural regions, showing a position root mean-squared error of 9.86 m and 10.37, respectively, over trajectories of 42.23 km and 56.56 km, respectively, while exploiting an average of about 19 and 10 eNodeBs, respectively.This work was supported in part by the Office of Naval Research (ONR) under Grant N00014-19-1-2511 and Grant N00014-19-1-2613, in part by the National Science Foundation (NSF) under Grant 2240512, in part by the U.S. Department of Transportation (USDOT) under Grant 69A3552047138 for the CARMEN University Transportation Center (UTC), and in part by the Air Force Office of Scientific Research (AFOSR) under Grant FA9550-22-1-0476. This work was also supported in part by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. SAND2022-13901

Evaluation of the 2010 Toyota Prius Hybrid Synergy Drive System

Subsystems of the 2010 Toyota Prius hybrid electric vehicle (HEV) were studied and tested as part of an intensive benchmarking effort carried out to produce detailed information concerning the current state of nondomestic alternative vehicle technologies. Feedback provided by benchmarking efforts is particularly useful to partners of the Vehicle Technologies collaborative research program as it is essential in establishing reasonable yet challenging programmatic goals which facilitate development of competitive technologies. The competitive nature set forth by the Vehicle Technologies Program (VTP) not only promotes energy independence and economic stability, it also advocates the advancement of alternative vehicle technologies in an overall global perspective. These technologies greatly facilitate the potential to reduce dependency on depleting natural resources and mitigate harmful impacts of transportation upon the environment