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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Buried Interfaces in Halide Perovskite Photovoltaics

Understanding the fundamental properties of buried interfaces in perovskite photovoltaics is of paramount importance to the enhancement of device efficiency and stability. Nevertheless, accessing buried interfaces poses a sizeable challenge because of their non-exposed feature. In this paper, the mystery of the buried interface in full device stacks is deciphered by combining advanced in situ spectroscopy techniques with a facile lift-off strategy. By establishing the microstructure-property relations, the basic losses at the contact interfaces are systematically presented, and it is found that the buried interface losses induced by both the sub-microscale extended imperfections and lead-halide inhomogeneities are major roadblocks toward improvement of device performance. The losses can be considerably mitigated by the use of a passivation-molecule-assisted microstructural reconstruction, which unlocks the full potential for improving device performance. The findings open a new avenue to understanding performance losses and thus the design of new passivation strategies to remove imperfections at the top surfaces and buried interfaces of perovskite photovoltaics, resulting in substantial enhancement in device performance.

36 MATERIALS SCIENCE↗
DOE OSTI2022

State-of-the-art and review of condensation heat transfer for small modular reactor passive safety: Experimental studies

Here this study focused on state-of-the-art and review of condensation heat transfer for small modular reactors (SMR). Nuclear reactors adopt passive containment cooling systems (PCCS) for accident mitigation, containment integrity, and primarily to maintain the last barrier for radioactive particle release to the environment during and beyond design-basis accidents. However, improving the effectiveness of the PCCS is more critical for the SMR than for commercial reactors to ensure higher safety margins and compactness. In the PCCS of SMR, due to its smaller size containment, the filmwise condensation (FWC) is dominant. Therefore, this study emphasized the FWC. Earlier condensation studies for the PCCS did not make SMR the primary focus, so a critical review for formulating the state-of-the-art was necessary. Part-1 of this study covered the review of physics phenomena, previous experimental studies with a brief overview of associated test facilities and empirical correlations. This study identified a research gap with the condensation test data scaling relations by using the information and findings of the previous PCCS studies and applied them to the SMR system.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS2011

RFI Mitigation and Detection for the SMAP Radar

The planned Soil Moisture Active Passive (SMAP) mission will use both active radar and passive radiometer instruments at L-Band to measure and monitor both soilmoisture and freeze/thaw state globally. The frequency band allocated for the SMAP radar is shared with the Global Navigation Satellite Systems and ground-basedradiolocation services. Signals from those users present significant sources of anthropogenic radio frequency interference (RFI) which contaminate the radarmeasurements. To mitigate RFI, the radar is designed with tunable operating frequency, which allows the center frequency to be tuned to avoid RFI. The filtering scheme in the receiver is configured to get a high level of RFI suppression. To meet the high accuracy measurement requirements, RFI detection and correction will be required during ground data processing. Some candidate algorithms have been evaluated, and they have been tested against simulated SMAP data derived from the PALSAR data.

Soil Moisture Active Passive (SMAP)↗
NASA NTRS2009

Overview of Materials International Space Station Experiment 7B

Materials International Space Station Experiment 7B (MISSE 7B) is the most recent in a series of experiments flown on the exterior of International Space Station for the purpose of determining the durability of materials and components in the space environment. A collaborative effort among the Department of Defense, the National Aeronautics and Space Administration, industry, and academia, MISSE 7B will be flying a number of NASA experiments designed to gain knowledge in the area of space environmental effects to mitigate risk for exploration missions. Consisting of trays called Passive Experiment Containers, the suitcase sized payload opens on hinges and allows active and passive experiments contained within to be exposed to the ram and wake or zenith and nadir directions in low Earth orbit, in essence, providing a test bed for atomic oxygen exposure, ultraviolet radiation exposure, charged particle radiation exposure, and thermal cycling. New for MISSE 7B is the ability to monitor experiments actively, with data sent back to Earth via International Space Station communications. NASA?s active and passive experiments cover a range of interest for the Agency. Materials relevant to the Constellation Program include: solar array materials, seal materials, and thermal protection system materials. Materials relevant to the Exploration Technology Development Program include: fabrics for spacesuits, materials for lunar dust mitigation, and new thermal control coatings. Sensors and components on MISSE 7B include: atomic oxygen fluence monitors, ultraviolet radiation sensors, and electro-optical components. In addition, fundamental space environmental durability science experiments are being flown to gather atomic oxygen erosion data and thin film polymer mechanical and optical property data relevant to lunar lander insulation and the James Web Space Telescope. This paper will present an overview of the NASA experiments to be flown on MISSE 7B, along with a summary of the thermal environment to be expected during the 1 yr mission scheduled for launch in 2009.

Jaworske, Donald A.↗
NASA NTRS2010

Meeting Radiation Protection Requirements and Reducing Spacecraft Mass - A Multifunctional Materials Approach

Both crew and radio-sensitive systems, especially electronics must be protected from the effects of the space radiation environment. One method of mitigating this radiation exposure is to use passive-shielding materials. In previous vehicle designs such as the International Space Station (ISS), materials such as aluminum and polyethylene have been used as parasitic shielding to protect crew and electronics from exposure, but these designs add mass and decrease the amount of usable volume inside the vehicle. Thus, it is of interest to understand whether structural materials can also be designed to provide the radiation shielding capability needed for crew and electronics, while still providing weight savings and increased useable volume when compared against previous vehicle shielding designs. In this paper, we present calculations and analysis using the HZETRN (deterministic) and FLUKA (Monte Carlo) codes to investigate the radiation mitigation properties of these structural shielding materials, which includes graded-Z and composite materials. This work is also a follow-on to an earlier paper, that compared computational results for three radiation transport codes, HZETRN, HETC, and FLUKA, using the Feb. 1956 solar particle event (SPE) spectrum. In the following analysis, we consider the October 1989 Ground Level Enhanced (GLE) SPE as the input source term based on the Band function fitting method. Using HZETRN and FLUKA, parametric absorbed doses at the center of a hemispherical structure on the lunar surface are calculated for various thicknesses of graded-Z layups and an all-aluminum structure. HZETRN and FLUKA calculations are compared and are in reasonable (18% to 27%) agreement. Both codes are in agreement with respect to the predicted shielding material performance trends. The results from both HZETRN and FLUKA are analyzed and the radiation protection properties and potential weight savings of various materials and materials lay-ups are compared.

Atwell, William↗
NASA NTRS2006

Mitigation of Terrestrial Radar Interference in L-Band Spaceborne Microwave Radiometers

Terrestrial radars operating in the 1215-1400 MHz radio-location and navigation spectrum allocation are important for air traffic safety, homeland security, and national defense. For low-frequency observations of soil moisture and ocean salinity, Earth-observing microwave radiometers are allocated Earth- Exploration Satellite Service (EESS) spectrum for operating at 1400-1427 MHz. The proximity of powerful long-range radars to the passive allocation makes observing a challenge. Three aspects of mitigation to RFI are discussed in this paper: survivability, operability, and excisability (SOE). Modeling and simulations of NASA's Hydros and Aquarius radiometers were performed to examine the impacts of radar interference. The results are applied to the three aspects of mitigation SOE and the affects on the radiometer requirements are discussed.

Piepmeier, Jeffrey R.↗
NASA NTRS2004

New Hydrophilic, Composite Membranes for Air Removal from Water Coolant Systems

Liquid coolants are commonly used as thermal transport media to increase efficiency and flexibility in aerospace vehicle design. The introduction of gas bubbles into the coolant can have negative consequences, including: loss of centrifugal pump prime, irregular sensor readings, and blockage of coolant flow to remote systems. One solution to mitigate these problems is the development of a passive gas removal device, or gas trap, installed in the flight cooling system. In this study, a new hydrophilic, composite membrane has been developed for passage of the coolant fluid and retention of gas bubbles. The trapped bubbles are subsequently vented from the system by a thin, hydrophobic, microporous membrane. The original design for this work employed a homogeneous membrane that was susceptible to fouling and pore plugging. Spare gas traps of this variety have degraded during storage, and recreation of the membranes has been complicated due to problems with polymer duplication and property variations in the final membranes. In this work, replacements have been developed based on deposition of a hydrophilic polymer on the bore-side of a porous polyethylene (PE) tube. The tube provides excellent chemical and mechanical stability, and the hydrophilic layer provides retention of gas bubbles. Preliminary results have shown that intimate contact is required between the deposited layer and the substrate to overcome material differences. This has been accomplished by presoaking the membrane tube in the solvent to raise its surface energy. Polymer solutions of various concentrations have been used to promote penetration of the polymer layer into the porous substrate and to control separation layer thickness. The resulting composite membranes have shown repeatable decrease in nitrogen permeability, which is indicative of a decrease in membrane pore size. Studies with water permeation have yielded similar results. We have observed some swelling of the added polymer layer, which causes a slight decrease in membrane pore size, and should result in improved bubble retention. Preliminary studies have also been performed on gas retention in flowing systems. Initial results have been promising, with negligible gas permeation for the coated membranes compared to 100% gas permeation in the uncoated tube.

Ritchie, Stephen M. C.↗
NASA NTRS2015

On Hilbert-Huang Transform Based Synthesis of a Signal Contaminated by Radio Frequency Interference or Fringes

Norden E. Huang et al. had proposed and published the Hilbert-Huang Transform (HHT) concept correspondently in 1996, 1998. The HHT is a novel method for adaptive spectral analysis of non-linear and non-stationary signals. The HHT comprises two components: - the Huang Empirical Mode Decomposition (EMD), resulting in an adaptive data-derived basis of Intrinsic Mode functions (IMFs), and the Hilbert Spectral Analysis (HSA1) based on the Hilbert Transform for 1-dimension (1D) applied to the EMD IMF's outcome. Although paper describes the HHT concept in great depth, it does not contain all needed methodology to implement the HHT computer code. In 2004, Semion Kizhner and Karin Blank implemented the reference digital HHT real-time data processing system for 1D (HHT-DPS Version 1.4). The case for 2-Dimension (2D) (HHT2) proved to be difficult due to the computational complexity of EMD for 2D (EMD2) and absence of a suitable Hilbert Transform for 2D spectral analysis (HSA2). The real-time EMD2 and HSA2 comprise the real-time HHT2. Kizhner completed the real-time EMD2 and the HSA2 reference digital implementations respectively in 2013 & 2014. Still, the HHT2 outcome synthesis remains an active research area. This paper presents the initial concepts and preliminary results of HHT2-based synthesis and its application to processing of signals contaminated by Radio-Frequency Interference (RFI), as well as optical systems' fringe detection and mitigation at design stage. The Soil Moisture Active Passive (SMAP mission (SMAP) carries a radiometer instrument that measures Earth soil moisture at L1 frequency (1.4 GHz polarimetric - H, V, 3rd and 4th Stokes parameters). There is abundant RFI at L1 and because soil moisture is a strategic parameter, it is important to be able to recover the RFI-contaminated measurement samples (15% of telemetry). State-of-the-art only allows RFI detection and removes RFI-contaminated measurements. The HHT-based analysis and synthesis facilitates recovery of measurements contaminated by all kinds of RFI, including jamming [7-8]. The fringes are inherent in optical systems and multi-layer complex contour expensive coatings are employed to remove the unwanted fringes. HHT2-based analysis allows test image decomposition to analyze and detect fringes, and HHT2-based synthesis of useful image.

Spacecraft Electronics Equipment↗
NASA NTRS2018

Modeling the Risk of U.S. Offshore Oil & Gas Exploration-Well Drilling, Commercial Nuclear Plants, and Human Spaceflight

Probabilistic Risk Assessment (PRA) has been applied in different industries for many years. Each industry and technology area presents varying challenges and priorities, and the risk models therefore need to be somewhat different. This paper compares aspects of risk modeling of offshore drilling, nuclear plant operation, and human spaceflight. Risk models in all three technology areas have certain high-level similarities: (1) they employ redundancy and diversity in their means to prevent or mitigate risk, including a mix of active and passive systems designed to respond to off-normal evolutions; (2) they are affected by human reliability; (3) their models require consideration of coupling between scenario structure and scenario phenomenology. But in examining the models in more detail, one sees important differences in methodology and emphasis. For purposes of comparison, this paper discusses aspects of a risk model of an offshore drilling operation in the U.S. Gulf of Mexico, focusing on where such a development differs in important ways from models of commercial U.S. nuclear plants and models developed for human spaceflight.

Boyer, Roger L.↗
NASA NTRS2021

Random vibration, exported vibration, and passive isolation testing of the Ricor K508N cryocooler

The Ricor K508N is a rotary Stirling Cryocooler whose predecessor, the K508, has extensive flight heritage. The K508N has significant potential as a low-cost option for CubeSat infrared electro-optical payload applications. This paper will explore the work done by the ATA project on the exported vibration characterization of a set of standard K508N cryocoolers (35 atm) and the implementation and performance comparison of several passive vibration isolation and damping technologies to help mitigate the jitter effect of COTS cryocoolers. Kistler Force dynamometers and accelerometers were used to measure the K508N’s body and cold tip Multicomponent Exported Forces and Torques (EFT). Wire rope and Pyrolytic Graphite Sheet thermal straps are used as vibration isolation technologies. The K508N also underwent sine sweep resonant and peak profile testing as well as random vibration testing to GEVS launch loads in a NanoRacks soft stow configuration.

Mok, M↗
NASA NTRS2006

Self-Passivating Lithium/Solid Electrolyte/Iodine Cells

Robust lithium/solid electrolyte/iodine electrochemical cells that offer significant advantages over commercial lithium/ iodine cells have been developed. At room temperature, these cells can be discharged at current densities 10 to 30 times those of commercial lithium/iodine cells. Moreover, from room temperature up to 80 C, the maximum discharge-current densities of these cells exceed those of all other solid-electrolyte-based cells. A cell of this type includes a metallic lithium anode in contact with a commercial flexible solid electrolyte film that, in turn, is in contact with an iodine/ graphite cathode. The solid electrolyte (the chemical composition of which has not been reported) offers the high ionic conductivity needed for high cell performance. However, the solid electrolyte exhibits an undesirable chemical reactivity to lithium that, if not mitigated, would render the solid electrolyte unsuitable for use in a lithium cell. In this cell, such mitigation is affected by the formation of a thin passivating layer of lithium iodide at the anode/electrolyte interface. Test cells of this type were fabricated from iodine/graphite cathode pellets, free-standing solid-electrolyte films, and lithium-foil anodes. The cathode mixtures were made by grinding together blends of nominally 10 weight percent graphite and 90 weight percent iodine. The cathode mixtures were then pressed into pellets at 36 kpsi (248 MPa) and inserted into coin-shaped stainless-steel cell cases that were coated with graphite paste to minimize corrosion. The solid-electrolyte film material was stamped to form circular pieces to fit in the coin cell cases, inserted in the cases, and pressed against the cathode pellets with polyethylene gaskets. Lithium-foil anodes were placed directly onto the electrolyte films. The layers described thus far were pressed and held together by stainless- steel shims, wave springs, and coin cell caps. The assembled cells were then crimped to form hermetic seals. It was found that the solid electrolyte films became discolored within seconds after they were placed in contact with the cathodes - a result of facile diffusion of iodine through the solid electrolyte material (see figure).

Bugga, Ratnakumar↗
DOE OSTI2021

Guidance for Monitoring Passive Groundwater Remedies Over Extended Time Scales

Passive remediation can be appropriate where natural processes and actions such as institutional controls mitigate exposure to contaminated groundwater, achieving remedial action objectives and protectiveness of human health and the environment. Monitored natural attenuation (MNA) is a prevalent passive remediation strategy supported by a regulatory framework and monitoring design guidance. However, long-term passive remedies are usually selected in combination with at least one active remedy, such as source removal, in situ treatment, or pump-and-treat, functioning as a complementary method for achieving remediation objectives and meeting the applicable statutory and regulatory requirements. However, MNA and existing monitoring guidance primarily target situations where the remedial action objectives are met within a few decades. When time scales for passive remediation extend to many decades (50 years or more), a corresponding change in monitoring strategy is needed to adapt to the extended time scale. This document provides guidance for implementing an extended-scale monitoring (ESM) approach appropriate for long-duration passive remediation. Extended-scale is defined in this document with respect to time (i.e., a long duration of remediation) and a large enough physical scale such that downstream receptors will not be impacted within the remediation timeframe. ESM applies to slow-moving groundwater contaminant plumes and emphasizes monitoring primarily for potential exposure pathways. For this approach, the primary monitoring objective is to demonstrate that the plume diminishes before reaching the receptor zone or point of compliance and/or a receptor does not receive concentrations above the compliance limit. While the overall objectives of protecting human health and the environment are the same as for plumes where remediation can occur over a shorter time period, the time scales between decisions are longer and the dynamics of plume evolution are slower. To this end, a scenario-based strategy is described for different plume and source conditions, defining a containment and receptor zones. The containment zone is the area where the risk of exposure to groundwater contamination can be mitigated (e.g., through institutional controls) during the remediation time period. The receptor zone is defined as the area where exposure to groundwater contamination cannot be mitigated and compliance concentration standards must be met. Within the containment zone, slow plume migration may occur, leading to concentrations that exceed compliance standards. However, where distance to the receptor zone is large relative to plume migration and attenuation rate, this approach can be protective of the receptor zone. Selection of a long-duration passive remedy needs to be based on sufficient understanding of contaminant sources, hydrogeology, and contaminant plumes. A strong technical basis, supported by predictive analysis, is recommended to substantiate that contamination is expected to stay within the containment zone during the active remediation and attainment phase of the remedy, and diminish to meet compliance standards within the extended timeframe prior to reaching the receptor zone (e.g., many decades or even centuries). The ESM approach is based on verification of plume behavior and not on detailed plume dynamics. Monitoring is conducted to confirm expected behavior with an emphasis on exposure pathways to verify that plumes remain contained in areas where the protectiveness objectives can be met. ESM should not be adopted if there is significant risk of the plume extending beyond the containment zone. Given the slow movement within the containment zone, less frequent sampling is required relative to approaches used for conventional-scale remediation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

IDENTIFICATION OF ADSORBA TION OF ADSORBATE FT-IR BANDS USING IN-SI -IR BANDS USING IN-SITU TECHNIQUES: Pd SPECIATION AND ADSORPTION CHEMISTRY OF Pd-ZEOLITES FOR PASSIVE NOx ADSORPTION

To meet increasingly stringent automotive emissions standards, further improvements in catalytic converter design are necessary. Current automotive catalyst systems are effective at eliminating emission of nitrogen oxides (NOx) once the catalyst reaches operational temperature (~200 °C). NOx emitted at lower catalyst temperatures now comprises most of the NOx released during a typical test cycle. Referred to as “the cold start problem” this issue has come to the forefront of automotive catalyst development, as mitigating these emissions is necessary to further reduce automotive emissions. Passive NOx adsorbers present an appealing solution to the cold start problem, these being a class of materials that chemisorb exhaust components such as NOx, carbon monoxide (CO) and hydrocarbons at near-ambient temperatures, and then desorb these compounds once the downstream catalyst has reached operational temperature. An effective passive NOx adsorber must have several properties: high NOx adsorption at near-ambient temperatures, near-complete NOx desorption at temperatures within the operational range, high thermal stability, and resistance to automotive exhaust components at high temperatures. The potential environmental impact of such a system is substantial, as NOx emissions currently result in the formation of millions of tons of smog and acid rain each year. Pd-exchanged zeolites have shown promise for deployment as Passive NOx adsorbers, though much remains to be understood about their adsorption chemistry and deactivation. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) provides a convenient probe of adsorbed species, most automotive exhaust components possessing IR-active chemical bonds. By examining the evolution of IR bands under various pretreatments and adsorbates, the overall Pd-speciation and adsorptive zeolite sites of each material can be characterized, and the identities of IR bands can be deduced. In this work, microreactor-MS analysis of the adsorption and desorption behavior of these materials was also examined, these results being coupled with in-situ DRIFTS temperature programmed desorption (TPD) to correlate desorption events with specific adsorbed species. A pair of zeolite frameworks of similar Si/Al ratio but differing pore size were examined, Beta zeolite (BEA) and Chabazite (CHA) representing a medium- and small-pore framework, respectively. The effect of Pd-loading on BEA was examined, as well as the various deactivation pathways and active sites of each material.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRSDate not supplied

Advancements in Lunar Dust Mitigation and Leveraging the Contamination Control Community

Lunar Dust Contamination: As we get closer to putting landers, rovers, payloads, and astronauts on the Moon, dust mitigation is becoming more critical than ever. To address the many challenges of dust mitigation on the surface, engineers and scientists are looking at various technologies that may have relevance for the contamination control community. This includes active, passive, architectural, and operational solutions. There have been advances in coatings for dust mitigation at NASA and through commercial partnerships (see Wiesner, Wohl, et al). There have been advancements to previous solutions as well as novel solutions to address dust mitigation on the surface and on-orbit. There have been several efforts to better understand the effectiveness of various terrestrial and dust mitigation solutions with much of this data published in recent years. In the area of dust mitigation, dust contamination or infiltration refers to the impingement or contact of planetary dust with items not normally dusty and whose operation may therefore be compromised. Recent Advancements in Dust Mitigation: Dust mitigation strategies are becoming more common for hardware heading to the Moon, with most major programs implementing lunar dust contamination requirements for human health and equipment. In the last couple of years, NASA has created more guidance to assist hardware developers with dust mitigation. This includes NASA-STD-1008 (Classifications and Requirements for Testing Systems and Hardware to be Exposed to Dust in Planetary) and NASA TP 20220018746 (Lunar Dust Mitigation Guide and Reference). Several projects are testing hardware in relevant dusty environments to understand their tolerance to lunar dust. There has been a significant increase in the amount of testing with lunar simulants, with the NASA Simulant Advisory Committee serving a resource for NASA and our partners. There are new solutions for detecting and monitoring the dust internally and externally. Learning from the contamination control community: In addition to sharing potentially relevant solutions at the workshop, the dust mitigation community is also interested in learning from the contamination control community on ways to address lunar dust. For instance, a major aspect of managing the dust is monitoring and detection. This is critical for understanding when maintenance is needed and to inform future missions. Another challenge of working with lunar dust is quantifying and characterizing the smallest of particles. There are also challenges in modeling lunar dust and its behavior. The dust mitigation community can also leverage lessons learned from the planetary protection community.

dust mitagation↗
DOE OSTI2025

Phase II Field Demonstration at Lansing Smith Generating Plant, Southport, Florida (Final Report)

The Final Technical Report: Field Test Design and Pressure Management Strategies for Phase II Field Demonstration of Optimal Pressure Control, Plume Management, and Produced Water Strategies presents the culmination of multi-year efforts under the U.S. Department of Energy’s Brine Extraction and Storage Test (BEST) program, led by EPRI in partnership with Gulf Power at the Plant Smith site near Panama City, Florida. The project was designed to evaluate and demonstrate the technical feasibility of managing subsurface pressures and fluid movement associated with large-scale CO₂ injection, using low-salinity water as a proxy fluid. Through a combination of field injection testing, reservoir modeling, and optimization studies, the research team developed and refined active and passive brine extraction strategies aimed at controlling injection-induced pressure buildup, mitigating risks of fault activation, and managing plume migration. The field demonstration incorporated a new injection well (TIW-2), a new monitoring/extraction well (TEMW-A), and an existing well (TIW-1) repurposed for passive pressure relief. Complementary geophysical monitoring was designed to track plume development and evaluate the effectiveness of pressure management strategies. The report details the integrated workflow encompassing wellfield development, regulatory permitting, model calibration, and survey design. It includes a comprehensive electromagnetic (EM) modeling and inversion study used to develop a cost-effective, time-lapse geophysical monitoring plan capable of imaging the evolving low-salinity plume within the highly saline Lower Tuscaloosa formation. Reservoir simulation results guided the design of the 17-month injection program and the timing of active extraction to maintain formation pressures below a hypothetical fault reactivation threshold. Supporting analyses evaluated potential injectivity risks related to clay fines migration and geochemical incompatibility, identifying practical mitigation measures such as salinity and pH control. The final design recommends a series of crosswell EM surveys—conducted before, during, and after injection—as the most effective and economical approach for plume imaging, supplemented by continuous downhole pressure and flow monitoring. Collectively, the study provides a field-ready framework for cost-effective pressure management and monitoring in support of future CO₂ storage projects.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS2003

Passive Isolators for use on the International Space Station

The value of the International Space Station (ISS) as a premier microgravity environment is currently at risk due to structure-borne vibration. The vibration sources are varied and include crew activities such as exercising or simply moving from module to module, and electro- mechanical equipment such as fans and pumps. Given such potential degradation of usable microgravity, anything that can be done to dampen vibration on-orbit will significantly benefit microgravity users. Most vibration isolation schemes, both active and passive, have proven to be expensive - both operationally and from the cost of integrating isolation systems into primary/secondary structural interfaces (e.g., the ISS module/rack interface). Recently, passively absorptive materials have been tested at the bolt interfaces between the operating equipment and support structure (secondary/tertiary structural interfaces). The results indicate that these materials may prove cost-effective in mitigating the vibrational problems of the ISS. We report herein tests of passive absorbers placed at the interface of a vibration-inducing component: the Development Distillation Assembly, a subassembly of the Urine Processing Assembly, which is a rotating centrifuge and cylinder assembly attached to a mounting plate. Passive isolators were installed between this mounting plate and its support shelf. Three materials were tested: BISCO HT-800, Sorbothane 30 and Sorbothane 50, plus a control test with a hard shim. In addition, four distinct combinations of the HT-800 and Sorbothane 50 were tested. Results show a significant (three orders of magnitude) reduction of transmitted energy, as measured in power spectral density (PSD), using the isolation materials. It is noted, however, that passive materials cannot prevent the transmission of very strong forces or absorb the total energy induced from structural resonances.

Houston, Janice↗
DOE OSTI2020

Guidance for Monitoring Passive Groundwater Remedies Over Extended Time Scales

Passive remediation can be appropriate where natural processes and actions such as institutional controls mitigate exposure to contaminated groundwater, achieving remedial action objectives and protectiveness of human health and the environment. Monitored natural attenuation (MNA) is a prevalent passive remediation strategy supported by a regulatory framework and monitoring design guidance. MNA can also be used after active remediation has been completed (e.g., pump-and-treat) as a polishing step to reach ultimate remedial action objectives. However, MNA and existing monitoring guidance primarily target situations where the remedial action objectives are met within a few decades. When timescales for passive remediation extend to many decades, a corresponding change in monitoring strategy is needed to adapt to the extended time scale. This document provides guidance for implementing an extended-scale monitoring (ESM) approach appropriate for long-duration passive remediation. Extended-scale is defined in this document with respect to time (i.e., a long duration of remediation) and a large enough physical scale such that receptors will not be impacted within the remediation timeframe.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗