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At least 1,495 records · Page 83

Gauging nexus between topological and fracton phases

Coupled layer constructions are a valuable tool for capturing the universal properties of certain interacting quantum phases of matter in terms of the simpler data that characterizes the underlying layers. In the study of fracton phases, the X-Cube model in 3+1D can be realized via such a construction by starting with a stack of 2+1D Toric Codes and turning on a coupling which condenses a composite "particle-string" object. In a recent work [Phys. Rev. B 112, 125124 (2025)], we have demonstrated that in fact, the particle-string can be viewed as a symmetry defect of a topological 1-form symmetry. In this paper, we study the result of gauging this symmetry in depth. We unveil a rich gauging web relating the X-Cube model to symmetry protected topological (SPT) phases protected by a mix of subsystem and higher-form symmetries, subsystem symmetry fractionalization in the 3+1D Toric Code, and non-trivial extensions of topological symmetries by subsystem symmetries. Here, our work emphasizes the importance of topological symmetries in non-topological, geometric phases of matter.

Anyons↗

Knowledge Base for Distributed Spacecraft Mission Design Using the Trade-Space Analysis Tool for Constellations (TAT-C)

Opportunities for multi-point measurements, greater revisit frequency, failure robustness, and improved cost effectiveness motivate consideration of Distributed Spacecraft Missions (DSMs) for future Earth science missions. However, careful analysis is required to assess the distributed sensing capabilities of a constellation compared to more mature monolithic spacecraft while also considering other important dimensions such as cost and risk. The large combinatorial DSM design space limits existing mission analysis tools and exploration methods which emphasize monolithic design variables. The Trade-space Analysis Tool for Constellations (TAT-C) under development at Goddard seeks to enumerate and evaluate alternative mission architectures to minimize cost and maximize scientific return for pre-defined goals during pre-phase A analysis.Similar to other model-centric engineering efforts, efficient data management is a significant challenge for DSM mission analysis. In TAT-C, a Knowledge Base (KB) is envisioned as a cumulative central repository of information and meta-information about DSMs. Initial KB concepts store related data for reuse within or across mission analyses; however, over time, the KB is envisioned to be an important layer to coordinate actions of both human analysts and automated design agents to search a large design space for desirable mission alternatives. Preliminary KB research builds on a modern web technology stack to provide the following functionality: 1) storage of trade-space search requests which set requirements and constraints for DSM concepts, 2) storage of analysis results which quantify performance metrics for evaluated DSM concepts, 3) a RESTful application programming interface (API) for scripted access to data from TAT-C modules, 4) web-based graphical user interface (GUI) for manual access to underlying data, and 5) access control and management restrictions relevant to data protection and security. These efforts have culminated in a prototype KB used by the research team during TAT-C development to assess opportunities for future work.

Pattern Recognition↗

Fabrication and Performance Characterization of Electrospun Nanofibers for Terrestrial and Space Applications

Passive thermal control is vital in space, especially for extended missions involving cryogen storage needing protection from sunlight. This presentation covers the development of a thermal coating with wavelength-selective characteristics using polymeric materials that scatter sunlight with minimal absorption, resulting in high solar reflectance. Furthermore, these coatings allow emission in infrared wavelengths, making them suitable for deep-space missions requiring extended storage. The study chose polymer and surface morphology suitable as solar reflectors that are lightweight, compact, and easily manufacturable, focusing on different multilayered nanofibers made using polytetrafluoroethylene and polyethylene-oxide (PTFE-PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and silica (SiO2). To understand how these materials interact with sunlight, we analyze light propagation through several layers of electrospun nanofibers to determine spectral reflectance, absorptance, and transmittance by solving the Maxwell equations. The model is also compared with measurements of spectral reflectance and transmittance of the various electrospun nanofibers using spectrophotometers interfaced with integrating spheres in the ultraviolet, visible, near-infrared, and mid-infrared wavelengths. The presentation will also describe the design and analysis, fabrication of the nanofibers using electrospinning, and several experimental characterization techniques to determine suitability for space applications. The nanofibers are tested using various tools to determine their suitability for cryogenic applications in space. Lastly, the samples were tested under low vacuum conditions and exposing them to sunlight inside a vacuum chamber maintained at 300 K. Relative to the incoming solar flux (1000 W/m2), only 1% of the energy was absorbed under these operating conditions. With further optimization and testing under high vacuum cryogenic environments, the samples could demonstrate much lower absorption or higher reflection of incoming solar radiation, which can translate to low temperatures suitable for cryogen storage.

Chieloka Ibekwe↗

Assembly of CMS Endcap MIP Timing Detector Module at FNAL

The High-Luminosity LHC (HL-LHC) will enable a more detailed exploration of new phenomena thanks to an anticipated increase in collisions where pileup is expected to reach approximately 200 simultaneous interactions. Many CMS systems will be significantly upgraded to prepare for this new era, including the MIP Timing Detector (MTD) project. The MTD is designed to mitigate the effect of pileup and is set to provide a timestamp accurate to 30 ~ 40 picoseconds for every event, ensuring sustained detector performance at HL-LHC. The MTD is divided into two sections, Barrel Timing Layer (BTL) and Endcap Timing Layer (ETL) which utilize different sensor and ASIC technologies due to the difference in active surfaces, irradiation conditions, and installation schedules. The ETL, composed of two double-sided disks, employs the Low Gain Avalanche Detector (LGAD) sensor and the Endcap Timing Readout Chip (ETROC). More than 8,000 modules, each consisting of four LGAD sensors and ETROCs are required for the ETL detector. These modules will be assembled using an automated robotic gantry that guarantees precise placement at a level of 10 micrometers. In addition, the full assembly of ETL modules includes film application with the jig, wire-bonding, encapsulation with the automated dispensing robot for protecting the wire-bonding, and film curing with a vacuum oven. This talk reports on the successfully completed throughput test with mockup components using the gantry and the successful assembly of real functional modules for beam tests at CERN and FNAL, including the first official ETL module.

Apresyan, Artur↗

Explosion Detection using Transfer Learning via YAMNet [Poster]

The acoustic data of explosions and noise collected on smartphones were fed to the YAMNet model to obtain the scores of each class. The data was split 60/20/20 for training, validation, and testing. A single-layered neural network was trained using the computed scores to predict if the data was an explosion or noise. The trained model was then combined with the YAMNet model. The combined model was tested with the ESC-50 dataset to investigate overall accuracy and class based false positive rates.

98 - NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL↗

Optical and other property changes of M-50 bearing steel surfaces for different lubricants and additive prior to scuffing

An ester lubricant base oil containing one or more standard additives to protect against wear, corrosion, and oxidation was used in an experimental ball/plate elastohydrodynamic contact under load and speed conditions such as to induce scuffing failure in short times. Both the ball and the plate were of identically treated M-50 steel. After various periods of operating time the wear track on the plate was examined with an interference microscope of plus or minus 30 A depth resolution and sometimes also with a scanning ellipsometer and an Auger spectrometer. The optically deduced surface profiles varied with wavelength, indicating the presence of surface coatings, which were confirmed by the other instruments. As scuffing was approached, a thin (approximately A) oxide layer and a carbide layer formed in the wear track in particular when tricresylphosphate antiwear additive was present in the lubricant. The rates of the formation of these layers and their reactivity toward dilute alcholic HCl depended strongly on the lubricant and additives. Based on these results suggestions for improved formulations and a test method for bearing reliability could be proposed.

Lauer, J. L.↗

Optical and other properties changes of M-50 bearing steel surfaces for different lubricants and additives prior to scuffing

An ester lubricant base oil containing one or more standard additives to protect against wear, corrosion, and oxidation was used in an experimental ball/plate elastohydrodynamic contact under load and speed conditions such as to induce scuffing failure in short times. Both the ball and the plate were of identically treated M-50 steel. After various periods of operating time the wear track on the plate was examined with an interference microscope of plus or minus 30 A depth resolution and sometimes also with a scanning ellipsometer and an Auger spectrometer. The optically deduced surface profiles varied with wavelength, indicating the presence of surface coatings, which were confirmed by the other instruments. As scuffing was approached, a thin (approximately A) oxide layer and a carbide layer formed in the wear track in particular when tricresylphosphate antiwear additive was present in the lubricant. The rates of the formation of these layers and their reactivity toward dilute alcoholic HCl depended strongly on the lubricant and additives. Based on these results suggestions for improved formulations and a test method for bearing reliability could be proposed.

Lauer, J. L.↗

Water Vapor Corrosion in EBC Constituent Materials

Environmental Barrier Coating (EBC) materials are sought after to protect ceramic matrix composites (CMC) in high temperature turbine engines. CMCs are particularly susceptible to degradation from oxidation, Ca-Al-Mg-Silicate (CMAS), and water vapor during high temperature operation which necessitates the use of EBCs. However, the work presented here focuses on water vapor induced recession in EBC constituent materials. For example, in the presence of water vapor, silica will react to form Si(OH)4 (g) which will eventually corrode the material away. To investigate the recession rate in EBC constituent materials under high temperature water vapor conditions, thermal gravimetric analysis (TGA) is employed. The degradation process can then be modeled through a simple boundary layer expression. Ultimately, comparisons are made between various single- and poly-crystalline materials (e.g. TiO2, SiO2) against those found in literature.

coating↗

Bio-inspired Surface Structures to Mitigate Interfacial Particle Adhesion and Erosion - A Review

Lunar dust known as regolith is a huge challenge for lunar exploration missions. Formed over millennia by a complex process involving impacts of meteoroids and micrometeoroids on the lunar surface, lunar dust is porous, highly abrasive with sharp jagged edges, chemically reactive, electrostatically charged and sometimes magnetic. The chemical composition and thickness of the dust layer also varies in different regions of the lunar surface. From samples obtained by previous lunar missions, the average particle size is below 100 microns. This dust has the tendency to strongly adhere to any exposed surfaces, and often degrades the material functionality to eventually cause failure. Any material on the lunar surface is also subject to harsh temperature cycles ranging from -178 ̊C to + 123 ̊C and extreme ultraviolet radiation. While on the lunar surface, different classes of materials would be required for different applications. Advanced materials have been and will be used throughout the lunar lander, habitat, and mission equipment. Examples include: polymeric materials for astronaut protective clothing; metals and ceramics for the lunar lander legs and habitats, and excavating equipment; and semiconductors for solar panels and on-board electronics. In all these applications, the surfaces of the materials are expected or understood to be exposed to the extreme lunar environment condition that includes the regolith dust. During the Apollo missions, the dust clung to and abraded the astronaut’s suits, degraded seals, optics, clogged sensors and reduced performance of thermal radiators. The lunar dust adheres to the surface by various mechanisms, which include electrostatic and Coulombic interactions, Van-der-Waals forces, magnetic forces, mechanical interlocking, chemical bonding and donor-acceptor interactions. There are three primary strategies for developing technologies to minimize the lunar dust adhesion: active, passive and a combination of active and passive. In the active approach, an external energy is needed to prevent or remove particles from collecting on the surface. Mechanically powered brushes and electrodynamic dust screens are two examples. In the passive approach, no external power is needed, and the material surface properties are able to mitigate dust adhesion. A well-known example of this strategy is the low work function coatings for non-stick surfaces. In most cases a combination of active and passive methods might be needed to optimally manage the lunar regolith. The passive method is significantly more attractive as it does not require any external power or an additional control subsystem. These approaches optimize the mission payload and reduce risk. Surface modification to minimize the dust adhesion is thus very important to lunar missions. Here, naturally evolved surface structures might provide guidance for solutions. There are several factors that have to be considered for minimizing particle adhesion to a surface. These include the substrate material properties, surface topography, chemistry, and the characteristics of the adhering particles. When engineering a surface, the substrate material chosen would be dependent on the needs of the application. Tailoring the surface microstructure or chemistry opens up more possibilities for its optimal utilization

Lunar Dust↗

Heatshield for Extreme Entry Environment Technology (HEEET) Development Status

The Heat shield for Extreme Entry Environment Technology (HEEET) Project is a NASA STMD and SMD co-funded effort. The goal is to develop and mission infuse a new ablative Thermal Protection System that can withstand extreme entry. It is targeted to support NASAs high priority missions, as defined in the latest decadal survey, to destinations such as Venus and Saturn in-situ robotic science missions. Entry into these planetary atmospheres results in extreme heating. The entry peak heat-flux and associated pressure are estimated to be between one and two orders of magnitude higher than those experienced by Mars Science Laboratory or Lunar return missions. In the recent New Frontiers community announcement NASA has indicated that it is considering providing an increase to the PI managed mission cost (PIMMC) for investigations utilizing the Heat Shield for Extreme Entry Environment Technology (HEEET) and in addition, NASA is considering limiting the risk assessment to only their accommodation on the spacecraft and the mission environment. The HEEET ablative TPS utilizes 3D weaving technology to manufacture a dual layer material architecture. The 3-D weaving allows for flat panels to be woven. The dual layer consists of a top layer designed to withstand the extreme external environment while the inner or insulating layer by design, is designed to achieve low thermal conductivity, and it keeps the heat from conducting towards the structure underneath. Both arc jet testing combined with material properties have been used to develop thermal response models that allows for comparison of performance with heritage carbon phenolic. A 50 mass efficiency is achieved by the dual layer construct compared to carbon phenolic for a broad range of missions both to Saturn and Venus. The 3-D woven flat preforms are molded to achieve the shape as they are compliant and then resin infusion with curing forms a rigid panels. These panels are then bonded on to the aeroshell structure. Gaps exist between the panels and these gaps have to be filled with seams. The seam material then has to be bonded on to adjacent panels and also to the structure. The heat-shield assembly is shown in Figure 1. One of the significant challenges we have overcome recently is the design, development and testing of the seam. HEEET material development and the seam concept development have utilized some of the unique test capabilities available in the US. The various test facilities utilized in thermal testing along with the entry environment for Saturn and Venus missions are shown in Figure 2. The HEEET project is currently in its 3rd year of a four-year development. Figure 3 illustrates the key accomplishments to date and the challenges yet to be overcome before the technology is ready for mission infusion. This proposed presentation will cover both progress that has been made in the HEEET project and also the challenges to be overcome that is highlighted in Figure 3. Objective of the HEEET project is to mature the system in time to support the next New Frontiers opportunity and we believe we are well along the way to mission infuse HEEET.

Thermal Protection System↗

Multiscale Modeling of Ablation and Pyrolysis in PICA-Like materials

During atmospheric entry of planetary probes, the thermal protection system (TIPS) of the probe is exposed to high temperatures under low pressures. In these conditions, carbonous fibrous TIPS materials may undergo oxidation leading to mass loss and wall recession called ablation. This work aims to improve the understanding of material/environment interactions through a study of the coupling between oxygen transport in the Knudsen regime, heterogeneous oxidation of carbon, and surface recession. A 3D Random Walk Monte Carlo simulation tool is used for this study. The fibrous architecture of a model material, consisting of high porosity random array of carbon fibers, is numerically represented on a 3D Cartesian grid. Mass transport in the Knudsen regime from the boundary layer to the surface, and inside this porous material is simulated by random walk. A reaction probability is used to simulate the heterogeneous oxidation reaction. The surface recession of the fibers is followed by front tracking using a simplified marching cube approach. The output data of the simulations are ablation velocity and dynamic evolution of the material porosity. A parametric study is carried out to analyze the material behavior as a function of Knudsen number for the porous media (length of the mean free path compared to the mean pore diameter) and the intrinsic reactivity of the carbon fibers. The model is applied to Stardust mission reentry conditions and explains the unexpected behavior of the TIPS material that underwent mass loss in volume.

Lachaud, Jean↗

Investigation of thermal protection systems effects on viscid and inviscid flow fields for manned entry systems

Procedures and methods for predicting aerothermodynamic heating to delta orbiter shuttle vehicles were reviewed. A number of approximate methods were found to be adequate for large scale parameter studies, but are considered inadequate for final design calculations. It is recommended that final design calculations be based on a computer code which accounts for nonequilibrium chemistry, streamline spreading, entropy swallowing, and turbulence. It is further recommended that this code be developed with the intent that it can be directly coupled with an exact inviscid flow field calculation when the latter becomes available. A nonsimilar, equilibrium chemistry computer code (BLIMP) was used to evaluate the effects of entropy swallowing, turbulence, and various three dimensional approximations. These solutions were compared with available wind tunnel data. It was found study that, for wind tunnel conditions, the effect of entropy swallowing and three dimensionality are small for laminar boundary layers but entropy swallowing causes a significant increase in turbulent heat transfer. However, it is noted that even small effects (say, 10-20%) may be important for the shuttle reusability concept.

Bartlett, E. P.↗

A Privacy-Preserving Strategy for the Trust Layer of the Energy Grid of Things Distributed Energy Resource Management System

Emergent from the shadows of the traditional grid flaws, the Smart Grid (SG) idea was born and led by government mandates toward cleaner energy production. The SG represents the next generation of electricity distribution systems that subsume recent technological innovations. It uses digital communication between its components and entities to attain more automation, self-sufficiency, and reliability. Unfortunately, this relatively new concept is not flawless; the intrinsic reliance on increased digital communication spreads open attack paths for adversaries. Therefore, finding solutions that address information exchange vulnerabilities has become imperative. The Energy Grid of Things (EGoT) is Portland State University’s (PSU’s) implementation of a Distributed Energy Resource Management System (DERMS). The EGoT DERMS requires access to customers’ information to achieve operational objectives. The system’s access to customers’ information needs to be restricted such that it does not violate customers’ privacy. Applying privacy protection models such as K-anonymity to EGoT DERMS sub-components safeguards that privacy. This thesis work proposes a strategy to ensure communication in the EGoT DERMS is privacy-preserving and secure. Specifically, it provides an approach to applying the Mondrian Algorithm to ensure data within the system excludes Personally Identifiable Information (PII) and provides means for securing the communication according to industry standards (IEEE 2030.5). Results suggest that the generalization hierarchy derived for the EGoT DERMS exhibits an Identical Generalization Hierarchy structure. Guarantees of sameness manifested in the test feeder topology would not hold in real-world scenarios. This thesis work proposes a strategy to ensure communication in the EGoT DERMS is privacy-preserving and secure. Specifically, it provides an approach to applying the Mondrian Algorithm to ensure data within the system excludes Personally Identifiable Information (PII) and provides means for securing the communication according to industry standards (IEEE 2030.5). Results suggest that the generalization hierarchy derived for the EGoT DERMS exhibits an Identical Generalization Hierarchy structure. Guarantees of sameness manifested in the test feeder topology would not hold in real-world scenarios.

Alsiad, Mohammed↗

Tuning Molecular Interactions between Peptoids and Substrates to Achieve Surface-Agnostic Coating

Achieving programmable and robust coatings that maintain functionality while adhering to various surface types with molecular-level tunability and programmable features remains challenging. In this study, we develop adaptable and stable surface-agnostic coatings (SACs) based on crystalline peptoid membranes by tuning interpeptoid and peptoid-substrate interactions. We utilize two complementary methods: (1) surfaceinduced assembly, where peptoid membranes form directly on substrates, and (2) depositing preformed peptoid crystalline membranes via an aqueous layer-by-layer (LbL) assembly technique. These strategies are applied to substrates with diverse surface chemistries and topographies, including mica, highly ordered pyrolytic graphite (HOPG), MoS 2 , sapphire, and porous membranes like porous alumina and polysulfide. Atomic force microscopy confirms the formation of peptoid coatings and reveals differences in assembly behavior across surfaces. Moisture vapor transport measurements serve as a proof-of-concept test for membrane continuity and tunable permeance. Together, these findings demonstrate the adaptability and programmability of peptoid-based SACs, enabling rational coating design on surfaces with diverse chemical and topographical features. Furthermore, this work opens pathways for using peptoid membranes as programmable surface modifiers in functional interfaces, protective coatings, and membrane platforms.

biomimetic polymers↗

Deliberate Motion Analytics Fused Radar and Video Test Results Deployed Beyond the Perimeter Fence in a High Noise Environment

Security systems that protect the nation’s critical facilities must be capable of detecting physical intrusions in all weather conditions. Intrusion detection sensors in a perimeter with a high nuisance alarm rate (NAR) significantly undermine detection performance and degrade security system effectiveness. This research demonstrated a fused sensor system that can differentiate foliage and weather-induced nuisance alarms from those caused by intruders, providing reliable detection within a two-fence perimeter or beyond the fence. A key element of this work is the creation and application of a “deliberate motion algorithm” that fuses alarm data from radar and video analytics to create video motion detection fused radar system. The two-layer architecture of the algorithm uses machine learning, multi-hypothesis tracking, and Dynamic Bayes Nets to differentiate intruder alarms from weather induced alarms.

47 OTHER INSTRUMENTATION↗

Arc-jet test and analysis of Orbiter TPS inter-tile heating in high pressure gradient flow

During entry of the Space Shuttle Orbiter, the convective heating within inter-tile gaps of the Thermal Protection System (TPS) material produces elevated tile sidewall temperatures in regions of high surface pressure gradient. Arc-jet tests have been conducted recently to obtain a measure of the gap heating down the TPS tile sidewalls at test conditions representative of Orbiter flight environments. The object of this paper is to present the gap heating correlations that were developed from a thermal analysis for 3-D curved and flat TPS tile segments. Predictions of gap sidewall temperature were obtained within 30 F of test data on both Wing Glove and Double Wedge models. Derived heating ratios were obtained for a range of test conditions (pressure, pressure gradient, enthalpy, boundary layer thickness, gap width, surface temperature, etc.). The results of the study, which showed that heating ratios varied with the pressure gradient times the square root of the surface pressure, are being used to provide an assessment of gap filler requirements on Orbiter forward fuselage/chine and wing glove regions.

Rochelle, W. C.↗

SiC and Si3N4 Recession Due to SiO2 Scale Volatility Under Combustor Conditions

SiC and Si3N4 materials were tested under various turbine engine combustion environments, chosen to represent either conventional fuel-lean or fuel-rich mixtures proposed for high speed aircraft. Representative CVD, sintered, and composite materials were evaluated in both furnace and high pressure burner rig exposure. While protective SiO2 scales form in all cases, evidence is presented to support paralinear growth kinetics, i.e. parabolic growth moderated simultaneously by linear volatilization. The volatility rate is dependent on temperature, moisture content, system pressure, and gas velocity. The burner tests were used to map SiO2 volatility (and SiC recession) over a range of temperature, pressure, and velocity. The functional dependency of material recession (volatility) that emerged followed the form: exp(-QIRT) * P(exp x) * v(exp y). These empirical relations were compared to rates predicted from the thermodynamics of volatile SiO and SiO(sub x)H(sub Y) reaction products and a kinetic model of diffusion through a moving, boundary layer. For typical combustion conditions, recession of 0.2 to 2 micron/h is predicted at 1200- 1400C, far in excess of acceptable long term limits.

Smialek, James L.↗

Modeling of the Ablation of Fibrous Materials in the Knudsen Regime

During atmospheric entry of planetary probes, the thermal protection system (TPS) of the probe is exposed to high temperatures under low pressures. In these conditions, carbonous TPS materials undergo gasification in the Knudsen regime leading to mass loss and wall recession called ablation. This work aims to improve the understanding of materiaVenvironment interactions through a study of the coupling between carbon dioxide transport in the Knudsen regime, heterogeneous oxidation of carbon, and sutface recession. A 3D Monte-Carlo simulation tool is used for this study. The fibrous architecture of the materiils, consisting of high porosity random array of carbon fibers, is numerically reproduced on a 3D Cartesian grid. Mass transport in the Knudsen regime from the boundary layer to the surface, and inside this porous material is simulated by random walk. A reaction probability is used to simulate the heterogeneous oxidation reaction. The surface recession is followed by front tracking using a simplified marching cube approach. The output data of the simulations are ablation velocity and dynamic evolution of the material porosity. A parametric study is carried out to analyze the material behavior as a function of Knudsen number for the porous media (length of the mean free path compared to the mean pore diameter) and the intrinsic reactivity of the carbon fibers. The results enable extrapolation of laboratory experimental data to actual entry conditions.

Lachaud, J.↗