Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “reversible process”

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 307 records · Page 17

An empirical investigation of organic software product lines

Abstract Software product line engineering is a best practice for managing reuse in families of software systems that is increasingly being applied to novel and emerging domains. In this work we investigate the use of software product line engineering in one of these new domains, synthetic biology. In synthetic biology living organisms are programmed to perform new functions or improve existing functions. These programs are designed and constructed using small building blocks made out of DNA. We conjecture that there are families of products that consist of common and variable DNA parts, and we can leverage product line engineering to help synthetic biologists build, evolve, and reuse DNA parts. In this paper we perform an investigation of domain engineering that leverages an open-source repository of more than 45,000 reusable DNA parts. We show the feasibility of these new types of product line models by identifying features and related artifacts in up to 93.5% of products, and that there is indeed both commonality and variability. We then construct feature models for four commonly engineered functions leading to product lines ranging from 10 to 7.5 × 10 20 products. In a case study we demonstrate how we can use the feature models to help guide new experimentation in aspects of application engineering. Finally, in an empirical study we demonstrate the effectiveness and efficiency of automated reverse engineering on both complete and incomplete sets of products. In the process of these studies, we highlight key challenges and uncovered limitations of existing SPL techniques and tools which provide a roadmap for making SPL engineering applicable to new and emerging domains.

97 MATHEMATICS AND COMPUTING↗

Kinetic and modeling studies of the mechanism of the dehydrogenation of Mg(BH 4 ) 2 to Mg(B 3 H 8 ) 2

Since its discovery over 15 years ago, the reversible dehydrogenation of Mg(BH 4 ) 2 to Mg(B 3 H 8 ) 2 has remained one of the more intriguing hydrogen-cycling systems. While the mechanism of this reaction has been the subject of a good deal of speculation and computational studies, prior to this work it had not been probed through kinetic studies. Previous reports of the dehydrogenation of Mg(BH 4 ) 2 to Mg(B 3 H 8 ) 2 have not included kinetic studies. The present studies have shown that the dehydrogenation of Mg(BH 4 ) 2 to Mg(B 3 H 8 ) 2 is suppressed by hydrogen pressure indicating that the rate-limiting step in this process involves hydrogen elimination. Computational modeling of kinetic data obtained from monitoring the hydrogen elimination from Mg(BH 4 ) 2 to Mg(B 3 H 8 ) 2 under static vacuum over a range of temperatures supports that the dehydrogenation occurs through a reversible three-step process in which the elimination of hydrogen from the [B 3 H 10 ] − intermediate is rate limiting. A mechanism involving the low energy transfer of neighboring BH3 groups is proposed to account for the formation of [B 3 H 8 ] − at relatively low temperatures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

TEA of a Unique Two-Pathways Process for Post-Combustion CO 2 Capture

A unique two-Pathways process using aqueous sodium glycinate for CO 2 capture from a split flue gas stream emitted from 600 MWe post-combustion coal power plant was developed in Aspen Plus v.10. The split gas flow rate used was 44.75 ton/h and contained 0.0023 mol% SO 2 and 13.33 mol% CO 2 . The process includes a washing unit, a CO 2 absorption unit, a reverse osmosis unit, and a solvent regeneration unit or an ultrafiltration unit. The washing unit uses deionized water to completely remove SO 2 and the CO 2 absorption unit uses SGS to capture at least 90 mol% of the CO 2 in the split flue gas stream. Upon CO 2 and SGS reactions, the resulting liquid products exhibit phase-separation into CO 2 -lean phase and CO 2 -rich phase, allow two distinct pathways. Pathway (i) is to regenerate mostly the CO 2 -rich phase, collect the released CO 2 , and compress it for sequestration purposes. Pathway (ii) is to send the liquid stream from the CO 2 absorption unit to the ultrafiltration unit to separate the solid nanomaterials. The hydraulics and mass transfer characteristics in the washing and CO 2 absorption units were obtained; and techno-economic analysis (TEA) for Pathways (i) and (ii), including Capital Expenditure (CAPEX), Operating Expenditure (OPEX), and Levelized Cost of CO 2 Captured (LCOC), were calculated and compared. The simulation results revealed that the CAPEX, OPEX, and LCOC for Pathway (i) were ($\$12,039,251$), (261 dollar/h), and (54.01 dollar/ton-CO 2 captured), respectively, and those for Pathway (ii) were ($\$5,908,000$), (237.2 dollar/h), and (39.90 dollar/ton-CO 2 captured), respectively. Moreover, in Pathway (ii), 8.19 ton/h of CO 2 were captured to produce 15.62 ton/h NaHCO 3 nanomaterials, which were sold to offset the overall process cost. The LCOC values indicate that Pathway (ii) is more cost-effective than Pathway (i) because LCOC values for Pathway (ii) are much lower than those for Pathway (i).COC values for Pathway (ii) are much lower than those for Pathway (i).

20 FOSSIL-FUELED POWER PLANTS↗

Rupture Dynamics Simulations of Shallow Crustal Earthquakes on Reverse Slip Faults

The main goal of this study was to perform dynamic rupture simulations in order constrain the characterization of kinematic rupture models implemented in techniques for simulating strong ground motion for crustal earthquakes. First, we investigated the rupture process of the 2008 Iwate-Miyagi Nairiku earthquake by developing a dynamic rupture model on a reverse fault using a trial-and-error technique that produced a slip distribution and near-fault ground motion that matched the recorded ones. The simulations were performed in the frequency range 0-2 Hz, using a 3D staggered grid finite-difference method and a linear slip weakening friction law. Constrained by the observed slip distribution and consistent with dynamic rupture models, the derived kinematic rupture model of the Iwate-Miyagi Nairiku earthquake contains areas with relatively large slip rate, representing strong motion generation areas, set against lower amplitude heterogeneous background slip, and a relatively low slip rate in the weak zone of the top-most crust (upper 3km). Second, we performed rupture dynamics modeling to constrain shallow slip characterization in rupture models for strike-slip crustal earthquakes. The objective was to establish general rules about the characterization of slip rate function and slip at shallow depths and in the strong motion generation areas (SMGAs). The simulations of spontaneous rupture were performed in the frequency range 0-2.0Hz, using a 3D staggered-grid finite-difference method and a layer over half-space 1D crustal velocity model with a minimum shear-wave velocity of 2.8 km/s. In order to account for changes in material ductility and reduction of stress drop, observed in the shallow crust (upper 3-5 km), and the transition from ductile state to brittle state in the upper seismogenic zone, in our stress models we included a shallow weak zone (<4km). In this zone the stress drop was set to zero at the free surface and gradually increased with depth, while the slip weakening distance was set to 75 cm at the free surface and decreased to 50 cm at the base of the weak zone. As in the case of reverse faulting during the Iwate-Miyagi Nairiku earthquake, from these computations we found a systematic change in the shape of the slip-rate function, from Kostrov-type in the deeper part of the fault to a more symmetric cosine-type in the upper few kilometers, near the free-surface. Moreover, the average slip duration in the weak zone, with respect to slip duration in the deeper parts of the fault, increases by at most a factor of 1.5. We found a systematic and gradual change in the shape of the slip-rate function from Kostrov-type in the asperity areas (SMGAs), to more symmetric cosine-type in the upper few km near the free-surface, on the long period motion generation area (LMGA). The effective rise time in the LMGA, with respect to that in the SMGAs, increases by at most a factor of 2. Effective rise time is the time difference between the time at which the slip rate drops to a level that is equal to 25% of its peak and the onset time of the signal. In addition, the slip in the LMGA located above the SMGAs is almost the same as the one in the SMGAs, and about 1.5 times larger than the average slip.

58 GEOSCIENCES↗

Investigation of the structure, filler interaction and degradation of disulfide elastomers made by Reversible Radical Recombination Polymerization (R3P)

In this paper we report the synthesis and analysis of cyclic polydisulfides, their redox depolymerization as well as their interaction with carbon black. Cyclic poly(3,6-dioxa-1,8-octanedithiol)s (pDODT) were synthesized by Reversible Radical Recombination Polymerization (R3P). R3P is a scalable “green” polymerization process using triethylamine (TEA), H 2 O 2 and air for the polymerization of dithiol monomers. pDODTs were synthesized in 5 and 20 g batches. The effect of peroxide concentration (3, 5, 10, 20, 30%) was investigated. It was found that the molecular weights increased exponentially with increasing peroxide concentrations. At 30% peroxide concentration pDODTs with M n up to 400,000 g/mol and polydispersity of 2 were obtained. 700 and 800 MHz NMR were used for investigating the chemical structure of the polymers. The absence of thiol end group signals in polymers made with > 10wt % H 2 O 2 and M n < 100,000 g/mol, including a sample of a fractionated polymer with starting Mn = 600,000 g/mol, verified cyclic structures. Dithiothreitol reduced the polymers to monomer and a small percentage of oligomers. Carbon black was shown to increase the moduli of high molecular weight pDODTs. Swelling tests in chloroform showed that polymers made with 20 and 30w% peroxide swelled 14 and 10 times of their starting weight without dissolving, indicating chemical interaction between the polymers and carbon black. In conclusion, further analysis of these interesting elastomers, available at the 20 g scale, is in progress.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Reversible (De)Intercalation of Hydrated Zn 2+ in Mg 2+ -Stabilized V 2 O 5 Nanobelts with High Areal Capacity

The rechargeable aqueous zinc ion battery (ZIB) is regarded as one of the most promising candidates for large-scale energy storage applications due to its low-cost and eco-friendly properties. However, the development of a suitable cathode operating with high areal capacity and uncovering the relevant reaction mechanisms remain challenging. Herein, the application of Mg 0.26 V 2 O 5 ∙0.73H 2 O (MVO) nanobelts as a ZIB cathode is demonstrated. In situ FT-IR reveals the shift of OH stretching from 3350 cm -1 to 3200 cm -1 , corresponding to the hydration shell of Zn 2+ , while in situ Raman suggests the interlayer charges creening effect, which would boost the intercalation of hydrated Zn 2+ . Density function theory reveals that the hydrated Zn 2+ can lower the Coulombic repulsion at the electrode-electrolyte interface and circumvents the desolvation penalty of hydrated Zn 2+ during the (de)intercalation process. Additionally, excellent structure stability and large interlayer spacing guarantee the highly reversible (de)intercalation of hydrated Zn 2+ . Therefore, the MVO nanobelts exhibit a high areal capacity of 2.12 mAh cm -2 at 0.05 A g -1 , outstanding cycling stability of 2500 cycles at 10 A g -1 with a mass loading of 5 mg cm -2 . Finally, it is believed that the use of hydrated intercalation charge carriers will boost further studies in other multivalent rechargeable batteries.

25 ENERGY STORAGE↗

Reassembled nanoprecipitates resisting radiation

Outstanding resistance to destructive radiation damage in structural alloys is realized by ultra-high-density reversible nanoprecipitate inclusions, and the improvement is attributed to the reordering process of low-misfit superlattices in highly supersaturated matrices.

36 MATERIALS SCIENCE↗

Local structure and distortions of mixed methane-carbon dioxide hydrates

A vast source of methane is found in gas hydrate deposits, which form naturally dispersed throughout ocean sediments and arctic permafrost. Methane may be obtained from hydrates by exchange with hydrocarbon byproduct carbon dioxide. It is imperative for the development of safe methane extraction and carbon dioxide sequestration to understand how methane and carbon dioxide co-occupy the same hydrate structure. Pair distribution functions (PDFs) provide atomic-scale structural insight into intermolecular interactions in methane and carbon dioxide hydrates. We present experimental neutron PDFs of methane, carbon dioxide and mixed methane-carbon dioxide hydrates at 10 K analyzed with complementing classical molecular dynamics simulations and Reverse Monte Carlo fitting. Mixed hydrate, which forms during the exchange process, is more locally disordered than methane or carbon dioxide hydrates. The behavior of mixed gas species cannot be interpolated from properties of pure compounds, and PDF measurements provide important understanding of how the guest composition impacts overall order in the hydrate structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Transpiration-powered desalination water bottle

Inspired by mangrove trees, we present a theoretical design and analysis of a portable desalinating water bottle powered by transpiration. The bottle includes an annular fin for absorbing solar heat, which is used to boost the evaporation rate of water from the interior synthetic leaf. This synthetic leaf comprises a nanoporous film deposited atop a supporting micromesh. Water evaporating from the leaf generates a highly negative Laplace pressure, which pulls the overlying source water across an upstream reverse osmosis membrane. Evaporated water is re-condensed in the bottom of the bottle for collection. The benefit of our hybrid approach to desalination is that reverse osmosis is spontaneously enabled by transpiration, while the thermal evaporation process is enhanced by heat localization and made more durable by pre-filtering the salt. Finally, we estimate that a 9.4 cm diameter bottle, with a 10 cm wide annular fin, could harvest about a liter of fresh water per day from ocean water.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

High-Performance/-Precision/-Z(HPPZ) Scintillator Grids via Advanced Electrochemistry. Phase I – Project # 20210572MFR- Mid year review [Slides]

Scintillation grids with improved imaging resolution in time and space, are required for future mission needs at various facilities (pRad user station, LANSCE, DARHT, Scorpius etc). Current technologies use inorganic crystal scintillators, which are positioned within a high-Z scintillator septa. Dense and high-Z materials are optimal for gamma-ray detection making them promising candidates for development of high -performance/-precision/-Z (HPPZ) scintillator grids. The current resolution of standard chemical etching and fabrication processes of high-Z materials is very low, leading to undesired undercutting and ultimately reducing crystal performance efficiency. Goals are to: Perform initial feasibility studies with the aim of producing complex parts for applications with difficult-to-process high-Z material; Use of pulse and pulse-reverse electrochemical methods on additive approaches to produce high-precision Au and Re scintillator grids at a small scale; and, Follow up in Phase II with the delivery of a large-scale scintillator grid of the best material candidate with unprecedented properties for LANL needs determined in Phase I.

36 MATERIALS SCIENCE↗

Efficient, reliable and cost-effective reversible solid oxide cell technology for hydrogen and electricity production

This report summarizes the work performed by University of California San Diego (UCSD) – OxEon Energy LLC (OxEon) for the U. S. Department of Energy/National Energy Technology Laboratory (DOE/NETL) under Cooperative Agreement DE-FE0031940 entitled “Efficient, Reliable and Cost Effective Reversible Solid Oxide Cell Technology for Hydrogen and Electricity Production”. This reversible solid oxide cell (RSOC) technology has two main novel elements: (i) a compact and low-cost stack architecture that consists of multi-cell cell modules in electrical parallel and series connections and (ii) high performance and fuel-flexible reversible cells with electrodes or all components made by sputtering deposition process for efficient operation in both fuel cell (power generation) and electrolysis (hydrogen production) modes.

30 DIRECT ENERGY CONVERSION↗

New 26 P( p, γ ) 27 S Thermonuclear Reaction Rate and Its Astrophysical Implications in the rp -process

Accurate nuclear reaction rates for 26 P(p, γ) 27 S are pivotal for a comprehensive understanding of the rp-process nucleosynthesis path in the region of proton-rich sulfur and phosphorus isotopes. However, large uncertainties still exist in the current rate of 26 P(p, γ) 27 S because of the lack of nuclear mass and energy level structure information for 27 S. We reevaluate this reaction rate using the experimentally constrained 27 S mass, together with the shell model predicted level structure. It is found that the 26 P(p, γ) 27 S reaction rate is dominated by a direct capture reaction mechanism despite the presence of three resonances at E = 1.104, 1.597, and 1.777 MeV above the proton threshold in 27 S. The new rate is overall smaller than the other previous rates from the Hauser–Feshbach statistical model by at least 1 order of magnitude in the temperature range of X-ray burst interest. In addition, we consistently update the photodisintegration rate using the new 27 S mass. The influence of new rates of forward and reverse reaction in the abundances of isotopes produced in the rp-process is explored by postprocessing nucleosynthesis calculations. The final abundance ratio of 27 S/ 26 P obtained using the new rates is only 10% of that from the old rate. The abundance flow calculations show that the reaction path 26 P(p, γ) 27 S(β + ,ν) 27 P is not as important as previously thought for producing 27 P. The adoption of the new reaction rates for 26 P(p, γ) 27 S only reduces the final production of aluminum by 7.1% and has no discernible impact on the yield of other elements.

79 ASTRONOMY AND ASTROPHYSICS↗

Evolution of Oxygen Ligands upon Large Redox Swings of Li 3 IrO 4

The limits of intercalation electrochemistry continue to be tested in the quest for ever increasing gains in the storage capability of Li-ion cathodes. The subsequent push for multi-electron reactivity has led to the recognition of the extremely versatile role of oxide ligands in charge compensation when there is a large redox swing. Li 3 IrO 4 is a unique model of such activity because it can reversibly cycle between Li 1 IrO 4 and Li 4.7 IrO 4 . In this study, X-ray spectroscopy, magnetic measurements and computational simulations uncover the evolution of O states in the different steps, compared to the involvement of Ir. While the process between Li 1 IrO 4 and Li 3 IrO 4 is dominated by the unconventional lattice oxygen redox, the process between Li 3 IrO 4 and Li 4.7 IrO 4 involves a conventional change of the formal oxidation state of Ir, which affects O due to the high covalency. The O states of Li 3 IrO 4 exhibit a very high reversibility after the whole 3.7-electron process, completely restoring the pristine state.

25 ENERGY STORAGE↗

Light controlled reversible Michael addition of cysteine: a new tool for dynamic site-specific labeling of proteins

Cysteine-based Michael addition is a widely employed strategy for covalent conjugation of proteins, peptides, and drugs. The covalent reaction is irreversible in most cases, leading to a lack of control over the process. Utilizing spectroscopic analyses along with X-ray crystallographic studies, we demonstrate Michael addition of an engineered cysteine residue in human Cellular Retinol Binding Protein II (hCRBPII) with a coumarin analog that creates a non-fluorescent complex. UV-illumination reverses the conjugation, yielding a fluorescent species, presumably through a retro-Michael process. Furthermore, this series of events can be repeated between a bound and non-bound form of the cysteine reversibly, resulting in the ON–OFF control of fluorescence. The details of the mechanism of photoswitching was illuminated by recapitulation of the process in light irradiated single crystals, confirming the mechanism at atomic resolution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Cigeo Design Options, Risks and Opportunities Management: A Continuous Project Management Goal - 20015

Andra is currently completing the detailed engineering phase of the stepwise design development of Cigeo, the French HLW and IL-LLW Deep Geological Repository. If licensed in the coming years, Cigeo's progressive construction, industrial operation and closure will last over more than a century. Such a duration, associated with the requirements in terms of reversibility, lead to the choice of an incremental design that allows, for next operator generations, to integrate improvements derived from scientific and technical progress as well as from experience feedback from its operation. This incremental design approach, associated with a permanent risks and opportunities management process, will continue after licensing of Cigeo as a tool for the governance of the reversibility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Boosting the Low-Temperature Performance of Graphite Anodes by Creating an Electrochemically Active Interface

Graphite is the major anode material used in commercial lithium-ion batteries (LIBs). However, the sluggish ion-transfer kinetics associated with graphite anodes significantly restrict the operation of LIBs over a wide temperature. This is primarily due to their low reversible capacity and the substantial overpotential exhibited under low-temperature conditions. To address this limitation, we demonstrate herein an approach that involves grafting an electrochemically active lithium benzenesulfonate layer onto a graphite surface through a typical reduction reaction of diazonium cations, followed by ion exchange process. This surface modification reduces the charge transfer resistance of graphite anodes, leading to an excellent reversible capacity of ~150 mAh g –1 at low-temperatures (-20 °C, 0.1C). Electrochemical impedance spectroscopy indicates that both desolvation of the lithium ions outside the graphite, and lithium diffusion within the solid electrolyte interphase and graphite lattice are two crucial rate-limiting steps during the Li (de)lithiation, with the latter dominating during the low-temperature operation. In conclusion, these findings demonstrate a facile method for enhancing the low-temperature performance of graphite through surface modification and provide valuable insights into fundamental understandings that can guide the future design of better -low-temperature graphite anodes.

25 ENERGY STORAGE↗

Low-temperature synthesis process of making MgzMxOy, where M is Mn, V or Fe, for manufacture of electrode materials for group II cation-based batteries

Preparation, characterization, and an electrochemical study of Mg 0.1 V 2 O 5 prepared by a novel sol-gel method with no high-temperature post-processing are disclosed. Cyclic voltammetry showed the material to be quasi-reversible, with improved kinetics in an acetonitrile-, relative to a carbonate-, based electrolyte. Galvanostatic test data under a C/10 discharge showed a delivered capacity >250 mAh/g over several cycles. Based on these results, a magnesium anode battery, as disclosed, would yield an average operating voltage ˜3.2 Volts with an energy density ˜800 mWh/g for the cathode material, making the newly synthesized material a viable cathode material for secondary magnesium batteries.

25 ENERGY STORAGE↗