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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

An expert system for a distributed real-time trainer

The problem addressed by this expert system concerns the expansion of capability of a Real Time Trainer for the Spacelab flight crew. As requirements for more models or fidelity are placed upon the system, expansion is necessary. The simulator can be expanded using a larger processor or by going to a distributed system and expand by adding additional processors. The distributed system is preferable because it is more economical and can be expanded in a more incremental manner. An expert system was developed to evaluate modeling and timing capability within a real time training simulator. The expert system is based upon a distributed configuration. Components of the modeled system are control tasks, network tasks, emulator tasks, processors, displays, and a network. The distributed module expert system (DMES) allows the configuring of processors, tasks, display use, keyboard use, and selection of alternate methods to update the data buffer. Modules can be defined with execution occurring in a specific processor on a network. The system consists of a knowledge front end editor to interactively generate or update the knowledge base, an inference engine, a display module, and a recording module.

Purinton, Steven C.↗
DOE OSTI2022

Oxyanion Surface Complexes Control the Kinetics and Pathway of Ferrihydrite Transformation to Goethite and Hematite

The rate and pathway of ferrihydrite (Fh) transformation at oxic conditions to more stable products is controlled largely by temperature, pH, and the presence of other ions in the system such as nitrate (NO 3 - ), sulfate (SO 4 2- ), and arsenate (AsO 4 3- ). Although the mechanism of Fh transformation and oxyanion complexation have been separately studied, the effect of surface complex type and strength on the rate and pathway remains only partly understood. We have developed a kinetic model that describes the effects of surface complex type and strength on Fh transformation to goethite (Gt) and hematite (Hm). Two sets of oxyanion-adsorbed Fh samples were prepared, nonbuffered and buffered, aged at 70 ± 1.5 °C, and then characterized using synchrotron X-ray scattering methods and wet chemical analysis. Kinetic modeling showed a significant decrease in the rate of Fh transformation for oxyanion surface complexes dominated by strong inner-sphere (SO 4 2- and AsO 4 3- ) versus weak outer-sphere (NO 3 - ) bonding and the control. The results also showed that the Fh transformation pathway is influenced by the type of surface complex such that with increasing strength of bonding, a smaller fraction of Gt forms compared with Hm. In conclusion, these findings are important for understanding and predicting the role of Fh in controlling the transport and fate of metal and metalloid oxyanions in natural and applied systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Electronic Structure of Double-Layer Epitaxial Graphene on SiC(0001) Modified by Gd Intercalation

In this work, we systematically study the effects of Gd adsorption and intercalation on the electronic band structure of double-layer epitaxial graphene on Si-terminated SiC(0001) by first-principles calculations. We show that Gd adsorption and intercalation exhibit strong effects on the coupling between the graphene layers and between the buffer layer and substrate. Different adsorption/intercalation geometries can result in very different electron band structures. The number of Dirac cones and the positions of the Dirac cones relative to the Fermi level can be effectively manipulated through controlling the Gd adsorption/intercalation geometries. Our calculations provide useful insights to guide the experimental design of graphene-based materials with desirable functionalities for applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Time-resolved cryogenic electron tomography for the study of transient cellular processes

Cryogenic electron tomography (cryo-ET) is the highest resolution imaging technique applicable to the life sciences, enabling sub-nanometer visualization of specimens preserved in their near native states. The rapid plunge freezing process used to prepare samples lends itself to time-resolved studies, which researchers have pursued for in vitro samples for decades. Here, we focus on developing a freezing apparatus for time-resolved studies in situ. The device mixes cellular samples with solution-phase stimulants before spraying them directly onto an electron microscopy grid that is transiting into cryogenic liquid ethane. By varying the flow rates of cell and stimulant solutions within the device, we can control the reaction time from tens of milliseconds to over a second prior to freezing. In a proof-of-principle demonstration, the freezing method is applied to a model bacterium, Caulobacter crescentus, mixed with an acidic buffer. Through cryo-ET we resolved structural changes throughout the cell, including surface-layer protein dissolution, outer membrane deformation, and cytosolic rearrangement, all within 1.5 seconds of reaction time. This new approach, Time-Resolved cryo-ET (TR-cryo-ET), enhances the capabilities of cryo-ET by incorporating a sub-second temporal axis and enables the visualization of induced structural changes at the molecular, organelle, or cellular level.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

A 30% reduction in switchgrass rhizome reserves did not decrease biomass yield

Abstract A long‐standing question in perennial grass breeding and physiology is whether yield improvement strategies could compromise winter survival. Since perennial grasses rely on stored carbohydrates for winter maintenance and spring regrowth, yield improvement strategies could reduce winter survival if they increase biomass and grain yields at the expense of carbon allocation to storage. Therefore, it is crucial to comprehend the dependence of regrowth on storage reserves. We experimentally depleted switchgrass ( Panicum virgatum L.) rhizome reserves by storing rhizomes for 2 weeks at 5°C (control treatment) and 25°C (reserve‐depleted treatment). During the storage period rhizome respiration was 5.3× higher at 25°C (0.010 μmol CO 2 g −1 min −1 at 5°C vs. 0.054 μmol CO 2 g −1 min −1 at 25°C; p < 0.0001) and the starch content was depleted by 30% by the end of storage. Surprisingly, reserve‐depleted switchgrass had 60% larger leaf area (LA; LA control = 149 cm 2 pot −1 vs. LA depleted = 239 cm 2 pot −1 ; p = 0.013) and produced ~40% more aboveground biomass than control plants (9.46 g pot −1 vs. 6.63 g pot −1 ; p = 0.112). In addition, reserve‐depleted switchgrass restored its rhizome starch reserves to pre‐storage levels. Switchgrass showed a large plasticity among its source‐sink components to buffer the imposed reserve depletion. It increased plant photosynthesis by increasing the photosynthetic leaf area while keeping photosynthesis constant on a leaf area basis and readjusted the timing and activity of sink organs. These results suggest that switchgrass, and potentially other perennial grasses, largely over‐invest in storage reserves. Therefore, current breeding strategies in perennial grasses aimed to extend the aboveground growing season should not compromise crop persistence. Our study also has implications on long‐term yield dynamics as it highlights sink limitations as potential driver of the yield decline commonly observed in perennial grasses 5+ years after cultivation.

Tejera‐Nieves, Mauricio↗
NASA NTRS1999

Design of the Wind Tunnel Model Communication Controller Board

The NASA Langley Research Center's Wind Tunnel Reinvestment project plans to shrink the existing data acquisition electronics to fit inside a wind tunnel model. Space limitations within a model necessitate a distributed system of Application Specific Integrated Circuits (ASICs) rather than a centralized system based on PC boards. This thesis will focus on the design of the prototype of the communication Controller board. A portion of the communication Controller board is to be used as the basis of an ASIC design. The communication Controller board will communicate between the internal model modules and the external data acquisition computer. This board is based around an Field Programmable Gate Array (FPGA), to allow for reconfigurability. In addition to the FPGA, this board contains buffer Random Access Memory (RAM), configuration memory (EEPROM), drivers for the communications ports, and passive components.

Wilson, William C.↗
DOE OSTI2023

Rapid Droplet Sampling Interface for Low-Volume, High-Throughput Mass Spectrometry Analysis

Here, we present a rapid droplet sampling interface (RDSI) electrospray ionization mass spectrometry (ESI-MS) system as a high-throughput, low-volume, noncontact, and minimal-carryover approach for characterization of liquids. Liquid characterization was achieved by combining droplet ejection with an open-face microflow capillary with a 2.5 μL/min continuous flow of carrier solvent. Through this implementation, single 0.3 nL droplets containing the analyte effectively mix with 4–8 nL of carrier solvent and create a combined electrospray plume. The carrier solvent continuously cleaned the system, eliminating carryover. A sampling rate of 5 Hz was achieved for droplets containing 1 μM propranolol or 5 μM leu-enkephalin with each droplet fully baseline-resolved (138 ± 32 ms baseline-to-baseline). Using a SCIEX API4000 mass spectrometer, a lower limit of quantification (LLOQ) of propranolol was 15 nM, corresponding to 1.16 fg of propranolol in the droplet, and was linear across 3 orders of magnitude. Further, quantitation could be achieved by adding an isotopically labeled internal standard, as done in conventional ESI. Signal transients were faster than the acquisition speed of the mass spectrometer, resulting in artificially high reproducibility of 15–30% RSD droplet-to-droplet. Analyte–solvent mixing ratios could be controlled by adjusting droplet positioning along the open-face capillary with an optimal position about 0.4 mm from the tip end. The range of analyte coverage was exemplified by measures of peptides and drugs in methanol, water, and buffer solutions. In a comparison to the Open Port Sampling Interface (OPSI) implemented on the same system, the RDSI had 78× greater sensitivity, 6× greater throughput and used significantly less carrier solvent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1981

The SMART MIL-STD-1553 bus adapter hardware manual

The SMART Multiplexer Interface Adapter, (SMIA) a complete system interface for message structure of the MIL-STD-1553, is described. It provides buffering and storage for transmitted and received data and handles all the necessary handshaking to interface between parallel 8-bit data bus and a MIL-STD serial bit stream. The bus adapter is configured as either a bus controller of a remote terminal interface. It is coupled directly to the multiplex bus, or stub coupled through an additional isolation transformer located at the connection point. Fault isolation resistors provide short circuit protection.

Ton, T. T.↗
NASA NTRS1990

Software For Numerically Controlled Machining

APT (Automatically Programmable Tools) system represents an adaptation, with enhancements, of public-domain version of APT IV/SSX8 to DEC VAX-11/780 computer for use by Engineering Services Division of NASA Goddard Space Flight Center. Enhancements include super pocket feature, which allows concave polygon pockets. Recent modifications include expansion of sizes of arrays and buffers to accommodate larger part programs, insertion of user-friendly error messages, and correction of programming errors that affect POCKET command and some of sculptured-surface commands (notably SSURF and SCURV). Consists of four components: translator, execution complex, subroutine library, and CL editor. Written in FORTRAN 77.

Premo, D. A.↗
DOE OSTI2024

In‐Situ Product Removal for the Enzymatic Depolymerization of Poly(ethylene terephthalate) via a Membrane Reactor

Poly(ethylene terephthalate) (PET) is a common single-use plastic and a major contributor to plastic waste. PET upcycling through enzymatic depolymerization has drawn significant interests, but lack of robust enzymes in acidic environments remains a challenge. This study investigates in-situ product removal (ISPR) of protons and monomers from enzymatic PET depolymerization via a membrane reactor, focusing on the ICCG variant of leaf branch compost cutinase. More than two-fold improvements in overall PET depolymerization and terephthalic acid yields were achieved employing ISPR for an initial PET loading of 10 mgPET ml buffer −1 . The benefit of ISPR was reduced for a lower initial loading of 1 mgPET ml buffer −1 due to decreased need for pH stabilization of the enzyme-containing solutions. A back-of-envelop analysis suggests that at a modest dilution ratio, ISPR could help achieve savings on caustic base solutions used for pH control in a bioreactor. Our study provides valuable insights for future ISPR developments for enzymatic PET depolymerization, addressing the pressing need for more sustainable solutions towards plastic recycling and environmental conservation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1983

A transceiver module of the Mu radar

The transceiver (TR) module of a middle and upper atmospheric radar is described. The TR module used in the radar is mainly composed of two units: a mixer (MIX unit) and a power amplifier (PA unit). The former generates the RF wave for transmission and converts the received echo to the IF signal. A 41.5-MHz local signal fed to mixers passes through a digitally controlled 8-bit phase shifter which can change its value up to 1,000 times in a second, so that the MU radar has the ability to steer its antenna direction quickly and flexibly. The MIX unit also contains a buffer amplifier and a gate for the transmitting signal and preamplifier for the received one whose noise figure is less than 5 dB. The PA unit amplifies the RF signal supplied from the MIX unit up to 63.7 dBm (2350 W), and feeds it to the crossed Yagi antenna.

Kato, S.↗
NASA NTRS1989

Human serum albumin crystals and method of preparation

Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies.

Carter, Daniel C.↗
NASA NTRS1990

RF/optical interference design for optical intersatellite links

A design approach for the RF/optical link interface for a data relay satellite is described. The flexibility of forward and return links in future data acquisition satellites in handling varying missions and data rates to 1 Gbit/s is considered. Attention is focused on requirements for the NASA Tracking and Data Acquisition System. System components are described including the return link multiplexer, the return link transmultiplexer, the forward link multiplexer, the forward link demultiplexer, and the frontside/backside switch. Ping-pong buffers, which provide rate buffering for each input data stream, are discussed and justification bits, which handle variations due to Doppler shift and local oscillator variation, are considered. The time-division multiplexed streams consist of a unique synchronization word for frame synchronization, and control words associated with each data burst to identify the presence or absence of a justification bit. Redundant data paths are described for both forward and return data streams.

Garlow, Ronald K.↗
NASA NTRS2000

Continuous Processing With Mars Gases

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO2 from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2. This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO2 capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous Supply Of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde↗
NASA NTRS2001

Continuous Processing with Mars Gases

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO, from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2, This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO, capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous supply of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde↗
DOE OSTI2024

Calibration of V-Notch and Compound Weirs for Subsurface Drainage Water Level Control Structures

Highlights Accurate discharge estimation is important when evaluating edge-of-field conservation practices. V-notch weir equations were developed for three sizes of subsurface drainage water level control structures. Compound weir equations were developed for subsurface drainage water level control structures. The compound weir equation accurately estimates discharge for flows within and overtopping the V-notch. Abstract.Numerous edge-of-field conservation practices use subsurface drainage water level control structures to monitor water levels and estimate discharge. In a control structure, procedures for calculating discharge when flow depth (head) exceeds the V-notch depth and overflows in the rectangular portion of the compound weir (CW) are ambiguous. In this study, we developed calibration equations for V-notch weirs in Agri Drain inline water level control structures of different sizes for flows within the V-notch and overtopping flow events. The discharge equation for overtopping events (Q CW , L s -1 ) was determined as: Q CW = a 1 (h b1 -h 1 b1 )+a 2 (W e -W v )h 1 b2 , where h and h 1 are heads above vertex/bottom and top of V-notch (cm), respectively, W is the effective crest width of rectangular weir (cm), W v is the top width of V-notch (cm), a 1 and b 1 are parameters for V-notch weir obtained by calibration, and a 2 and b 2 are calibration parameters for rectangular weir obtained from literature. Results were compared with a weir equation available in the literature (Q V+R ), which combines a V-notch equation with a head equal to V-depth and a rectangular weir equation for flow above V-depth. Discharge at overflow was estimated with high accuracy with Q CW, whereas Q V+R underestimated discharge (e.g., PBIAS of 0.67% vs. 17.82% for a 15.2 cm structure). An example using Q V+R resulted in a 14% lower annual estimation of nitrate-N load diverted to a saturated buffer than Q CW due to underestimation of drainage discharge during overflow events. Results suggest that the developed equation (Q CW ) accurately estimates discharge and will thus improve the estimated N load compared to Q V+R . Keywords: Compound weir, Flow monitoring, Subsurface drainage, V-notch weir, Water level control structure, Weir calibration.

Agriculture↗
DOE OSTI2020

Evaluation of Ammonia Discharge into PUREX Crib 216-A-37-1 and Nitrogen Species Fate in the Subsurface

Based on published data, this report identifies potential fate and transport mechanisms for the ammonium hydroxide condensate that was discharged to 216-A-37-1 Crib from Hanford fuel rod decladding before PUREX dissolution and separation operations. Crib 216-A-37-1 received 377 million liters of alkaline condensate discharged from March 1977 through April 1989. The following major processes were identified as controlling the ammonia (NH 3 ) fate and transport: 1. Liquid migration rates through the vadose zone 2. NH 3 microbial oxidation to nitrite and nitrate 3. Ammonia species [NH4 + , NH 3 (aq)] sorption to sediments 4. NH3 precipitation reactions after pH buffering occurs in sediments The travel time through the vadose zone was estimated to be 2.5 to 9 months during periods of high subsurface discharge rates. These travel times are based on tritium migration through the vadose zone, a co-contaminant also discharged to the 216-A-37-1 crib.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Nanostructured ZnO-Based Electrochemical Sensor with Anionic Surfactant for the Electroanalysis of Trimethoprim

In this research, detection of trimethoprim (TMP) was carried out using a nanostructured zinc oxide nanoparticle-modified carbon paste electrode (ZnO/CPE) with an anionic surfactant and sodium dodecyl sulphate (SDS) with the help of voltametric techniques. The electrochemical nature of TMP was studied in 0.2 M pH 3.0 phosphate-buffer solution (PBS). The developed electrode displayed the highest peak current compared to nascent CPE. Effects of variation in different parameters, such as pH, immersion time, scan rate, and concentration, were investigated. The electrode process of TMP was irreversible and diffusion controlled with two electrons transferred. The effective concentration range (8.0 × 10 -7 M–1.0 × 10 -5 M) of TMP was obtained by varying the concentration with a lower limit of detection obtained to be 2.58 × 10 -8 M. In addition, this approach was effectively employed in the detection of TMP in pharmaceutical dosages and samples of urine with the excellent recovery data, suggesting the potency of the developed electrode in clinical and pharmaceutical sample analysis.

36 MATERIALS SCIENCE↗