Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “controlled humidity”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A chamber design for closed ecological systems research

A single-plant growth chamber is described which is closed with respect to nutrient and gas flows, in order to serve as a tool in the investigation of control over biological systems. Such control procedures are essential for the use of biological components in the development of a closed ecological life support system (CELSS). The chamber's design consists of two concentric clear plastic cylinders equipped with aeroponic feed tubing, a supporting platform for the plant and a set of sensors that includes an anemometer, thermistors, pressure and strain gauges, and humidity sensors.

Schwartzkopf, H.↗
NASA NTRS1984

Flight evaluation of Spacelab 1 payload thermal/ECS interfaces

The Spacelab (SL-1) thermal/Environmental Control Systems (ECS) are discussed. Preflight analyses and flight data are compared in order to validate payload to Spacelab interfaces as well as corroborate modeling/analysis techniques. In doing so, a brief description of the Spacelab 1 payload configuration and the interactive Spacelab thermal/ECS systems are given. In particular, these interfaces address equipment cooling air, thermal and fluid conditions, humidity levels, both freon and water loop temperatures and load states, as well as passive radiant environment interfaces.

Ray, C. D.↗
NASA NTRS2021

Near-Global Variability of Stratospheric Water Vapor Observed by SAGE III/ISS

The Stratospheric Aerosol and Gas Experiment III instrument on the International Space Station (SAGE III/ISS) has been making high quality solar occultation measurements of stratospheric water vapor since June 2017. Here we evaluate the large-scale geophysical variability of the SAGE III/ISS water vapor measurements for the first 3 years of observations (2017–2020) as part of data validation for retrieval version 5.1 (v5.1). Detailed comparisons of SAGE III/ISS v5.1 with the Aura Microwave Limb Sounder (MLS) version 5 retrievals show overall excellent agreement in terms of seasonal mean structure and large-scale variability. SAGE III/ISS data capture the well-known seasonal variations in water vapor including the vertically propagating “tape recorder” in the tropics and lower stratospheric maxima linked to the NH summer monsoons. The high vertical resolution (∼2 km) measurements from SAGE III/ISS demonstrate contributions of the monsoons to the wet phase of “tape recorder” during the Northern Hemisphere (NH) summer. Interannual variations over the short data record are also consistent between SAGE III/ISS and MLS in the stratosphere between 16 and 30 km. We furthermore evaluate large-scale variations in relative humidity (RH) derived from the high vertical resolution SAGE III/ISS water vapor measurements, highlighting the detailed seasonal behavior and links to thermal structure near the tropical tropopause. Spatial distributions of RH at the cold point tropopause (CPT) show a close link between high RH and the minimum CPT temperature in both the NH winter and summer, consistent with temperature control of water vapor near the tropopause.

water vapor↗
NASA NTRS2011

The NASA Experience

Projects assigned to: (1) Testing, fixing, and procuring enclosure systems and components for Kennedy Ground Controls Systems at launch pad B. (2) Organizational spreadsheets for all subsystems involved in the project. (Procurement, parts lists, drawings, purchase requests, etc) (3) Resolve is a project devoted to the lunar rover that will sample lunar soil in an effort to remove the moister and separate the metal from the oxygen to produce drinkable water. I helped with the humidity environmental generator for the experiment (moister detector).

Ramos, Alberto↗
NASA NTRS1974

ERTS-1 data collection systems used to predict wheat disease severities

The author has identified the following significant results. The feasibility of using the data collection system on ERTS-1 to predict wheat leaf rust severity and resulting yield loss was tested. Ground-based data collection platforms (DCP'S), placed in two commercial wheat fields in Riley County, Kansas, transmitted to the satellite such meteorological information as maximum and minimum temperature, relative humidity, and hours of free moisture. Meteorological data received from the two DCP'S from April 23 to 29 were used to estimate the disease progress curve. Values from the curve were used to predict the percentage decrease in wheat yields resulting from leaf rust. Actual decrease in yield was obtained by applying a zinc and maneb spray (5.6 kg/ha) to control leaf rust, then comparing yields of the controlled (healthy) and the noncontrolled (rusted) areas. In each field a 9% decrease in yield was predicted by the DCP-derived data; actual decreases were 12% and 9%.

Kanemasu, E. T.↗
NASA NTRS1984

Methods for assessing the structural reliability of brittle materials

Failure from contact-induced surface flaws is considered along with controlled indentation flaws for construction of toughness and fatigue master maps, fatigue properties of ceramics with natural and controlled flaws, and a statistical analysis of size and stress state effects on the strength of an alumina ceramic. Attention is also given to dynamic and static fatigue of a machinable glass ceramic, the effect of multiregion crack growth on proof testing, and a fracture mechanics analysis of defect sizes. Other topics explored are related to the effect of temperature and humidity on delayed failure of optical glass fibers, subthreshold indentation flaws in the study of fatigue properties of ultrahigh-strength glass, the lifetime prediction for hot-pressed silicon nitride at high temperatures, static fatigue in high-performance ceramics, and requirements for flexure testing of brittle materials.

Freiman, S. W.↗
NASA NTRS2026

The Significance of Water Vapor Isotopes in Improving Weather Prediction

Water vapor isotopes carry the integrated history of evaporation, condensation, mixing, and transport. Although previous studies have shown potential to improve forecasts under controlled conditions, real-world applications have been limited by systematic biases in both models and satellite retrievals arising from sparse measurements in the free troposphere. Here we assimilate mid‑tropospheric δD retrievals (peak sensitivity ~4.2 km) from the Infrared Atmospheric Sounding Interferometer into the Isotope‑incorporated Global Spectral Model and evaluate the added value beyond co‑assimilated temperature and specific humidity with identical spatial and temporal coverage. Assimilating δD improves 0–120 h forecasts of wind, temperature, specific humidity, and geopotential height, with the largest gains in the midlatitudes; heavy‑precipitation skill also increases for thresholds >3 mm per 6 h. Demonstrated in a coarse‑resolution configuration with limited observations, the results indicate that isotopic information strengthens transport tracking and hydrological constraints, motivating evaluation in operational high‑resolution forecasting systems.

Hydrology↗
NASA NTRS1996

Biomass accumulation in hydroponically grown sweetpotato in a controlled environment: a preliminary study

In the development of a plant growth model, the assumptions made and the general equations representing an understanding of plant growth are gradually refined as more information is acquired through experimentation. One such experiment that contributed to sweetpotato model development consisted of measuring biomass accumulation of sweetpotato grown in hydroponic culture in a plant growth chamber. Plants were started from fifteen centimeter long 'TU-82-155' sweetpotato vine cuttings spaced 25 cm apart in each of 18 rectangular growing channels (0.15 by 0.15 by 1.2m) in a system designed to use the nutrient film technique (NFT). Each channel contained four plants. The 3.5m by 5.2m plant growth chamber environmental parameters included an 18h photoperiod, 500 micromoles m-2 s-1 of photosynthetic photon flux (PPF), and a diurnal light/dark temperature of 28 degrees C/22 degrees C. The relative humidity was 80 +/- 5% and the CO2 partial pressure was ambient (350 ppm). The nutrient solution contained in 30L reservoirs was a modified half Hoagland's solution with a 1:2.4 N:K ratio and a pH of 6.2. Solution replenishment occurred when the electrical conductivity (EC) level dropped below 1050. Plants were harvested at 15 days after planting (DAP) and weekly thereafter until day 134. By 57 DAP, stems and fibrous roots had acquired 90% of their total dry biomass, while leaves had reached 84% of their maximum dry biomass. Beginning at 64 DAP dry biomass accumulation in the storage roots dominated the increase in dry biomass for the plants. Dry weight of storage roots at 120 DAP was 165 g/plant or 1.1 kg/m2. Resulting growth curves were consistent with the physiological processes occurring in the plant. Results from this study will be incorporated in a plant growth model for use in conjunction with controlled life support systems for long-term manned space missions.

Biomass↗
NASA NTRS1995

Quantitative analysis of volatile organic compounds using ion mobility spectra and cascade correlation neural networks

Ion Mobility Spectrometry (IMS) is a powerful technique for trace organic analysis in the gas phase. Quantitative measurements are difficult, because IMS has a limited linear range. Factors that may affect the instrument response are pressure, temperature, and humidity. Nonlinear calibration methods, such as neural networks, may be ideally suited for IMS. Neural networks have the capability of modeling complex systems. Many neural networks suffer from long training times and overfitting. Cascade correlation neural networks train at very fast rates. They also build their own topology, that is a number of layers and number of units in each layer. By controlling the decay parameter in training neural networks, reproducible and general models may be obtained.

Harrington, Peter DEB.↗
NASA NTRS2023

Developing a Hybrid Space Suit Simulator as a Research Tool for Assessing Extravehicular Activity Relevant Workload

Suited testing time is limited and hard to come by, expensive, and requires a whole team to operate and monitor the suit; however, pressurized spacesuits are not always necessary for initial developmental efforts or assessment of informatics. The Human Physiology, Performance, Protection & Operations Laboratory (H-3PO) at NASA Johnson Space Center (JSC) is developing a Hybrid Space Suit Simulator (HS3) to support characterization of human performance during planetary surface exploration analogs. The primary goal of HS3 is to create a low cost, modular, and unpressurized suit simulator for use as a research tool which provides relevant physical and cognitive workload approximations with EVA-like immersion during planetary extravehicular activity (EVA) simulations. HS3 consists of a soft suit, communication, thermal control, gloves, boots, helmet, and integrated bioinformatics/sensors. The modular design of HS3 allows it to be modified to support test objectives as needed. HS3 enables H-3PO and NASA to complete critical human health and performance testing to address open risks and knowledge gaps in a timely, repeatable, and controlled manner. Four engineering runs were completed with HS3 as a baseline for capability. General workload was assessed while traversing on a passive treadmill and conducting geology tasks. Liquid cooling temperature, suit temperature, and metabolic rates were collected during one extended three-hour engineering run. For the duration of the engineering run the suit temperature was 26.6 ± 1.58 °C while suit humidity was 53.7 ± 5.11 %. Helmet temperature was higher than suit temperature at 27.8 ± 1.58 °C. Helmet humidity was lower than average suit humidity at 50.12 ± 11.3 °C. The liquid cooling temperature remained stable at 22.4 ± 1.62 °C. Resting metabolic rate was 597 ± 88 BTU/hr while metabolic rate increased during traverse tasks at 1500 ± 319 BTU/hr and geology tasks at 921 ± 129 BTU/hr. Following the engineering runs, a characterization study will be conducted. The subjects will perform EVA-like scenarios in both a shirtsleeve only and donned HS3, consisting of EVA task circuit focused on traversing, geological rock sampling, and task board manipulation. The characterization study will provide data capability for implementing HS3 in analog EVA testing environments.

Monica Hew↗
NASA NTRS1976

Studies of the exhaust products from solid propellant rocket motors

This study was undertaken to determine the feasibility of conducting environmental chamber tests on the physical processes which occur when a solid rocket motor exhaust mixes with the ambient atmosphere. Of particular interest was the interaction between hydrogen chloride, aluminum oxide, and water vapor. The program consisted of three phases: (1) building a small rocket motor and using it to provide the exhaust species in a controlled environment; (2) evaluating instruments used to detect and measure HCl concentrations and if possible determining whether the HCl existed in the gaseous state or as an acid aerosol; (3) monitoring a series of 6.4-percent scale space shuttle motor tests and comparing the results to the environmental chamber studies. Eighteen firings were conducted in an environmental chamber with the initial ambient relative humidity set at values from 29 to 100 percent. Two additional firings were made in a large shed, and four were made on an open concrete apron. Six test firings at MSFC were monitored, and the ground level concentrations are reported. Evidence is presented which shows that the larger Al2O3 (5 to 50 micrometers) particles from the rocket motor can act as condensation nuclei. Under appropriate ambient conditions where there is sufficient water vapor this results in the formation of an acid aerosol. Droplets of this acid were detected both in the environmental chamber and in the scaled shuttle engine tests.

Dawbarn, R.↗
NASA NTRS1992

Hydrotropism in pea roots in a porous-tube water delivery system

Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity.

NASA Program CELSS↗
NASA NTRS2012

The Potential for Hosted Payloads at NASA

The 2010 National Space Policy encourages federal agencies to actively explore the use of inventive, nontraditional arrangements for acquiring commercial space goods and services to meet United States Government requirements, including...hosting government capabilities on commercial spacecraft. NASA's Science Mission Directorate has taken an important step towards this goal by adding an option for hosted payload responses to its recent Announcement of Opportunity (AO) for Earth Venture-2 missions. Since NASA selects a significant portion of its science missions through a competitive process, it is useful to understand the implications that this process has on the feasibility of successfully proposing a commercially hosted payload mission. This paper describes some of the impediments associated with proposing a hosted payload mission to NASA, and offers suggestions on how these impediments might be addressed. Commercially hosted payloads provide a novel way to serve the needs of the science and technology demonstration communities at a fraction of the cost of a traditional Geostationary Earth Orbit (GEO) mission. The commercial communications industry launches over 20 satellites to GEO each year. By exercising this repeatable commercial paradigm of privately financed access to space with proven vendors, NASA can achieve science goals at a significantly lower cost than the current dedicated spacecraft and launch vehicle approach affords. Commercial hosting could open up a new realm of opportunities for NASA science missions to make measurements from GEO. This paper also briefly describes two GEO missions recommended by the National Academies of Science Earth Science Decadal Survey, the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission and the Precipitation and All-weather Temperature and Humidity (PATH) mission. Hosted payload missions recently selected for implementation by the Office of the Chief Technologist are also discussed. Finally, there are technical differences specific to hosted payloads and the GEO environment that must be considered when planning and developing a hosted payload mission. This paper addresses some of payload accommodation differences from the typical NASA LEO mission, including spacecraft interfaces, attitude control and knowledge, communications, data handling, mission operations, ground systems, and the thermal, radiation, and electromagnetic environment. The paper also discusses technical and programmatic differences such as limits to NASA's involvement with commercial quality assurance processes to conform to the commercial schedule and minimizing the price that makes hosted payloads an attractive option.

Andraschko, Mark↗
NASA NTRS2018

Characterization of Sorbents for Controlling Ammonia in Spacecraft Cabin Air

The trace contaminant control system (TCCS) utilizes packed beds of Barnebey-Sutcliffe (B-S) Type 3032 to remove ammonia from ISS (International Space Station) cabin air. BS Type 3032, an acid-impregnated activated carbon, is no longer produced and must be replaced. The adsorptive capacities of Calgon Carbon Ammonasorb II and Molecular Products Chemsorb® 1425 for ammonia were measured using moist (40% RH (Relative Humidity)) spacecraft simulated gas streams. These candidate replacement sorbents had 66% greater ammonia removal capacities at low (5 ppm) ammonia concentrations than B-S Type 3032.

Monje, Oscar↗
NASA NTRS2020

LaRC SmartLab Apps For Instrument Control and Data Processing: Laboratory Environment Monitor

The LaRC SmartLab applications are a series of software tools to greatly enhance researcher efficiency by streamlining and automating workflows. Python scripts and applications are increasingly being used in scientific workflows, including for instrument control and data processing. Interactive Python scripting environments such as JupyterLab provide powerful tools for using Python. In some use cases, the development of standalone applications with dedicated graphical user interfaces can enhance the utility of the code and open it up to more users, including non-programmers. Here, we describe a Python based application for communicating with, and displaying data from, iTHX Temperature, Humidity, and Dew Point probes. We discuss the set up and use of the application as well as its implementation. We also highlight the use of Simulated probes to enable users and developers to familiarize with or debug the application, even when they do not have access to the physical hardware in the laboratory.

LaRC SmartLab↗
NASA NTRS1999

Adsorption processes in spacecraft environmental control and life support systems

The environmental control and life support system on a spacecraft maintains a safe and comfortable environment in which the crew can live and work by supplying oxygen and water and by removing carbon dioxide, water vapor, and trace contaminants from cabin air. Although open-loop systems have been used successfully in the past for short-duration missions, the economics of current and future long-duration missions in space will make nearly complete recycling of air and water imperative. A variety of operations will be necessary to achieve the goal of nearly complete recycling. These include separation and reduction of carbon dioxide, removal of trace gas-phase contaminants, recovery and purification of humidity condensate, purification and polishing of wastewater streams, and others. Several of these can be performed totally or in part by adsorption processes. These processes are good candidates to perform separations and purifications in space due to their gravity independence, high reliability, relative high energy efficiency, design flexibility, technological maturity, and regenerative nature. For these reasons, adsorption has historically played a key role in life support on U.S. and Russian piloted spacecraft. Among the life support applications that can be achieved through use of adsorption technology are removal of trace contaminants and carbon dioxide from cabin air and recovery of potable water from waste streams. In each of these cases adsorption technology has been selected for use onboard the International Space Station. The requirements, science, and hardware for these applications are discussed. Human space exploration may eventually lead to construction of planetary habitats. These habitats may provide additional opportunities for use of adsorption processes, such as control of greenhouse gas composition, and may have different resources available to them, such as gases present in the planetary atmosphere. Separation and purification processes based on adsorption can be expected to continue to fulfill environmental control and life support needs on future missions.

Review, Tutorial↗
NASA NTRS1981

Meteorological lidar developments

A research program on remote optical measurements of humidity and temperature is summarized, and new results are given of such measurements as well as new data on the near IR absorption spectrum of H2O. The basic atmospheric technique is differential absorption lidar (DIAL) using narrow band, tunable dye lasers. Approximate wavelengths are 720, 820, 940 nm (H2O) and 690, 760 nm (O2; temperature). The requisite absorption line strengths and widths are measured in a controlled environment by means of grating spectroscopy and tunable lasers. Prospects for routine lidar meteorology, even from airplane and satellite platforms, appear excellent in several important applications; the conditions and the optical properties of the atmosphere can be obtained remotely by these means.

Wilkerson, T. D.↗
NASA NTRS2001

Ice Nucleation in Deep Convection

The processes controlling production of ice crystals in deep, rapidly ascending convective columns are poorly understood due to the difficulties involved with either modeling or in situ sampling of these violent clouds. A large number of ice crystals are no doubt generated when droplets freeze at about -40 C. However, at higher levels, these crystals are likely depleted due to precipitation and detrainment. As the ice surface area decreases, the relative humidity can increase well above ice saturation, resulting in bursts of ice nucleation. We will present simulations of these processes using a large-eddy simulation model with detailed microphysics. Size bins are included for aerosols, liquid droplets, ice crystals, and mixed-phase (ice/liquid) hydrometers. Microphysical processes simulated include droplet activation, freezing, melting, homogeneous freezing of sulfate aerosols, and heterogeneous ice nucleation. We are focusing on the importance of ice nucleation events in the upper part of the cloud at temperatures below -40 C. We will show that the ultimate evolution of the cloud in this region (and the anvil produced by the convection) is sensitive to these ice nucleation events, and hence to the composition of upper tropospheric aerosols that get entrained into the convective column.

Jensen, Eric↗