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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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Biomass and pigment production for Arthrospira platensis via semi-continuous cultivation in photobioreactors: Temperature effects
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Hydrothermal liquefaction of biomass: Developments from batch to continuous process
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Investigation of a submerged membrane reactor for continuous biomass hydrolysis
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Continuous hydrodeoxygenation of lignin to jet-range aromatic hydrocarbons
Sustainable aviation fuel (SAF) is essential to decrease the carbon footprint of the aviation industry. Although many strategies have been developed to provide the branched, aliphatic components of SAF, few viable strategies have been demonstrated to supply the aromatic and cycloalkane fraction of SAF at the necessary scale from bio-based feedstocks. Lignin is the largest natural source of renewable aromatic compounds, yet major challenges in deoxygenation have prevented its use as a feedstock for SAF. Here we report a continuous, two-stage catalytic process using molybdenum carbide to deoxygenate lignin from poplar into aromatic hydrocarbons with 87.5% selectivity towards aromatic hydrocarbons at 86% of the theoretical carbon recovery. This work demonstrates an effective approach to convert lignin into aromatic SAF blendstocks.
Pilot-Scale Continuous Plug-Flow Hydrothermal Liquefaction of Food Waste for Biocrude Production
Pilot-scale hydrothermal liquefaction (HTL) of biowaste is a critical step toward commercialization of the HTL technology. Despite many HTL studies conducted with wet biomass, including food waste, few were performed with a pilot-scale continuous plug-flow reactor (PFR), with the biocrude yield and quality analysis based on dewatering (ASTM D2892 Annex X1). This paper describes the development and performance evaluation of a mobile pilot-scale HTL continuous PFR, with a processing capacity of 60 L/h of wet feedstock and 6 L/h of biocrude production. The reactor system was designed for reaction conditions of up to 325 °C and 17.25 MPa. The reactor has a volume of 28.88 L with an additional counterflow heat exchanger volume of 18.07 L. Two types of food wastes, from a food processing plant and grocery store, were processed at 280 °C for 30 min, producing biocrude oil yields of 52.19 and 47.06 wt %, energy recoveries of 68.17 and 70.77%, and carbon recoveries of 66.91 and 64.78%, respectively. Furthermore, due to its high feedstock capacity and reaction volume, large amounts of biocrude oil and post-HTL wastewater (PHW) were obtained from this pilot-scale reactor to allow downstream research on upgrading biocrude oil for transportation fuel as well as PHW treatment and nutrient recovery.
Nonadiabatic Dynamics in a Continuous Circularly Polarized Laser Field with Floquet Phase-Space Surface Hopping
Non-adiabatic chemical reactions involving continuous circularly polarized light (cw CPL) have not attracted as much attention as dynamics in unpolarized/linearly polarized light. However, including circularly (in contrast to linearly) polarized light allows one to effectively introduce a complex-valued time-dependent Hamiltonian, which offers a new path for control or exploration through the introduction of Berry forces. Here, we investigate several inexpensive semiclassical approaches for modeling such nonadiabatic dynamics in the presence of a time-dependent complex-valued Hamiltonian, beginning with a straightforward instantaneous adiabatic fewest-switches surface hopping (IA-FSSH) approach (where the electronic states depend on position and time), continuing to a standard Floquet fewest switches surface hopping (F-FSSH) approach (where the electronic states depend on position and frequency), and ending with an exotic Floquet phase-space surface hopping (F-PSSH) approach (wherethe electronic states depend on position, frequency, and momentum). Using a set of model systems with time-dependent complex-valued Hamiltonians, we show that the Floquet phase- space adiabats are the optimal choice of basis as far as accounting for Berry phase effects and delivering accuracy. Furthermore, the F-PSSH algorithm sets the stage for modeling nonadiabatic dynamics under strong externally pumped circular polarization in the future.
Development and Scale-up of Continuous Electrocatalytic Hydrogenation of Functionalized Nitro arenes, Nitriles and Unsaturated Aldehydes
Electrolysis reactors based on the filter-press architecture of redox flow batteries have proven to be effective and scalable towards the production of commercially relevant, pharmaceutical quantities of anilines (>500 kg/year) from halogen-, hydroxyl-, and carbonyl-substituted nitroarenes. Turbulent flow through the carbon felts on which the catalysts were supported facilitated scaling towards production levels because it conferred on the reactors scale-independent, plug flow-like residence time distributions and high mass transfer coefficients. Equipping the cells with micro-reference electrodes made it possible to transfer reaction conditions first developed in batch systems to the continuous flow reactors. The catalysts prepared by incipient wetness impregnation of metal salts into lightly oxidized carbon felt supports were readily generalizable.
Continuous flash sublimation of inorganic halide perovskites: overcoming rate and continuity limitations of vapor deposition
Continuous Flash Sublimation (CFS) is a vapor deposition technique that shows commercially relevant deposition rates, is amenable to continuous operation, and exceeds previously reported efficiencies for the same material class.
Analysis of continuously rotating quadrupole focusing channels using generalized Courant-Snyder theory
By extending the recently developed generalized Courant-Snyder theory for coupled transverse beam dynamics, we have constructed the Gaussian beam distribution and its projections with arbitrary mode emittance ratios. The new formulation has been applied to a continuously rotating quadrupole focusing channel because the basic properties of this channel are known theoretically and could also be investigated experimentally in a compact setup such as the linear Paul trap configuration. The new formulation retains a remarkably similar mathematical structure to the original Courant-Snyder theory, and thus, provides a powerful theoretical tool to investigate coupled transverse beam dynamics in general and more complex linear focusing channels.
Compact CH 4 sensor system based on a continuous-wave, low power consumption, room temperature interband cascade laser
A tunable diode laser absorption spectroscopy-based methane sensor, employing a dense-pattern multi-pass gas cell and a 3.3 µm, CW, DFB, room temperature interband cascade laser (ICL), is reported. The optical integration based on an advanced folded optical path design and an efficient ICL control system with appropriate electrical power management resulted in a CH 4 sensor with a small footprint (32 x 20 x 17 cm 3 ) and low-power consumption (6 W). Polynomial and least-squares fit algorithms are employed to remove the baseline of the spectral scan and retrieve CH 4 concentrations, respectively. An Allan-Werle deviation analysis shows that the measurement precision can reach 1.4 ppb for a 60 s averaging time. Continuous measurements covering a seven-day period were performed to demonstrate the stability and robustness of the reported CH 4 sensor system.
Continuously tunable uniaxial strain control of van der Waals heterostructure devices
Uniaxial strain has been widely used as a powerful tool for investigating and controlling the properties of quantum materials. However, existing strain techniques have so far mostly been limited to use with bulk crystals. Although recent progress has been made in extending the application of strain to two-dimensional van der Waals (vdW) heterostructures, these techniques have been limited to optical characterization and extremely simple electrical device geometries. Here, we report a piezoelectric-based in situ uniaxial strain technique enabling simultaneous electrical transport and optical spectroscopy characterization of dual-gated vdW heterostructure devices. Critically, our technique remains compatible with vdW heterostructure devices of arbitrary complexity fabricated on conventional silicon/silicon dioxide wafer substrates. We demonstrate a large and continuously tunable strain of up to –0.15% at millikelvin temperatures, with larger strain values also likely achievable. We quantify the strain transmission from the silicon wafer to the vdW heterostructure, and further demonstrate the ability of strain to modify the electronic properties of twisted bilayer graphene. Our technique provides a highly versatile new method for exploring the effect of uniaxial strain on both the electrical and optical properties of vdW heterostructures and can be easily extended to include additional characterization techniques.
Performance of a continuously rotating half-wave plate on the POLARBEAR telescope
A continuously rotating half-wave plate (CRHWP) is a promising tool to improve the sensitivity to large angular scales in cosmic microwave background (CMB) polarization measurements. With a CRHWP, single detectors can measure three of the Stokes parameters, I, Q and U, thereby avoiding the set of systematic errors that can be introduced by mismatches in the properties of orthogonal detector pairs. We focus on the implementation of CRHWPs in large aperture telescopes (i.e. the primary mirror is larger than the current maximum half-wave plate diameter of ~0.5 m), where the CRHWP can be placed between the primary mirror and focal plane. In this configuration, one needs to address the intensity to polarization (I→P) leakage of the optics, which becomes a source of 1/f noise and also causes differential gain systematics that arise from CMB temperature fluctuations. In this paper, we present the performance of a CRHWP installed in the {\scshape Polarbear} experiment, which employs a Gregorian telescope with a 2.5 m primary illumination pattern. The CRHWP is placed near the prime focus between the primary and secondary mirrors. We find that the I→P leakage is larger than the expectation from the physical properties of our primary mirror, resulting in a 1/f knee of 100 mHz. The excess leakage could be due to imperfections in the detector system, i.e. detector non-linearity in the responsivity and time-constant. We demonstrate, however, that by subtracting the leakage correlated with the intensity signal, the 1/f noise knee frequency is reduced to 32 mHz (ℓ ~ 39 for our scan strategy), which is very promising to probe the primordial B-mode signal. We also discuss methods for further noise subtraction in future projects where the precise temperature control of instrumental components and the leakage reduction will play a key role.
A Radiation Weather Station: Development of a Continuous Monitoring System for the Collection, Analysis, and Display of Environmental Radiation Data
Due to heightened fear surrounding the possibility of future terrorism involving nuclear weapons and radiological dispersive devices, compounded by nonroutine nuclear power plant releases such as from emergencies or accidents, interest in contamination levels of environmental radiation has spiked. This project sought to develop a continuously operational radiation-monitoring system, with graphically visualized data easily accessible to the public. Because this continuing project is housed at a university facility, it bears no connection to perceived political or commercial interests, generally increasing the credibility of the endeavor. Outdoor weather and radiation parameters were gathered by sensors installed on the rooftop of a two-story building. A display and cloud service website was used to project the live data in an understandable format. A correlation was observed between weather and visibly heightened levels of gamma radiation. Furthermore, the goal of this paper is to share and highlight the overall hardware selection and the unique software challenges encountered when developing a robust collection and analysis system, along with the challenges of displaying meteorological and radiological data in a clear and concise fashion.
Systems and methods that use harmonic drives for converting reciprocating axial motion to continuous rotary motion, helical drives for converting reciprocating rotary motion to reciprocating axial motion and combinations thereof for converting reciprocating rotary motion to continuous rotary motion
A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations.
Systems and methods that use harmonic drives for converting reciprocating axial motion to continuous rotary motion, helical drives for converting reciprocating rotary motion to reciprocating axial motion and combinations thereof for converting reciprocating rotary motion to continuous rotary motion
A harmonic drive assembly and fluid-powered linear motors with both axial pistons are rotary piston arrangements incorporating the harmonic drive assembly are disclosed. The motors may be used in downhole drilling applications, but the drive assembly and/or motors may be used in other applications. The assembly, motors and methods use advanced harmonic drives, advanced helical drives, and combinations thereof with 1) motors with axial pistons and reciprocating linear rings to convert reciprocative axial motion to continuous rotary motion, and 2) motors with rotary pistons and reciprocating linear rings to rectify reciprocative rotary motion to continual rotary motion to improve performance over prior configurations. Axial pistons provide a robust simple solution for generating rotation; Rotational pistons provide increased torque generation as the torque generated is proportional to motor length. Since downhole drills are long, a high-torque motor can be produced using this method.