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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Quantifying CO 2 storage efficiency factors in hydrocarbon reservoirs. A detailed look at CO 2 Enhanced Oil Recovery

Carbon dioxide (CO 2 ) enhanced oil recovery (EOR) will likely be the primary means of geologic CO 2 storage during the early stages of commercial-scale carbon capture and storage (CCS) because of the inherent economic incentives as well as the abundant experience and demonstrated success in the United States, where CO 2 EOR has been employed since 1974. The work presented here estimates CO 2 storage efficiency factors in CO 2 EOR operations using a unique industry database of CO 2 EOR sites and 12 different reservoir simulation models. The simulation models encompass fluvial clastic and shallow shelf carbonate depositional environments for reservoir depths of 1219 and 2438 m (4000 and 8000 feet) and 7.6-, 20-, and 64-m (25-, 66-, and 209-foot)-thick pay zones. A novel statistical modeling technique incorporating the Michaelis–Menten function is used to generate empirical percentile estimates of CO 2 storage efficiency factors. West Texas San Andres dolomite water alternating gas (WAG) CO 2 flood performance data were used to derive P10, P50, and P90 CO 2 storage efficiency factors of 0.76, 1.28, and 1.74 Mscf/STB (stock tank barrel) of original oil in place. Median CO 2 storage efficiency factors from continuous CO 2 injection following conventional waterflood varied from 15% to 61% and 8% to 40% for fluvial clastic and shallow shelf carbonate simulation models, respectively, while those from WAG injection varied from 14% to 42% and 8% to 31%, respectively. Variation in the CO 2 storage efficiency factors was largely attributable to reservoir depth (a surrogate for reservoir pressure and temperature) and lithology (clastic versus carbonate). The results of this work provide practical information that can be used to quantify CO 2 storage resource estimates in oil reservoirs during CO 2 EOR operations (as opposed to storage following depletion) and the uncertainty associated with those estimates.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Prospective Coronary Heart Disease Screening in Asymptomatic Hodgkin Lymphoma Patients Using Coronary Computed Tomography Angiography: Results and Risk Factor Analysis

Purpose: To prospectively investigate the coronary artery status using coronary CT angiography (CCTA) in patients with Hodgkin lymphoma treated with combined modalities and mediastinal irradiation. Methods and Materials: All consecutive asymptomatic patients with Hodgkin lymphoma entered the study during follow-up, from August 2007 to May 2012. Coronary CT angiography was performed, and risk factors were recorded along with leukocyte telomere length (LTL) measurements. Results: One hundred seventy-nine patients entered the 5-year study. The median follow-up was 11.6 years (range, 2.1-40.2 years), and the median interval between treatment and the CCTA was 9.5 years (range, 0.5-40 years). Coronary artery abnormalities were demonstrated in 46 patients (26%). Coronary CT angiography abnormalities were detected in nearly 15% of the patients within the first 5 years after treatment. A significant increase (34%) occurred 10 years after treatment (P=.05). Stenoses were mostly nonostial. Severe stenoses were observed in 12 (6.7%) of the patients, entailing surgery with either angioplasty with stent placement or bypass grafting in 10 of them (5.5%). A multivariate analysis demonstrated that age at treatment, hypertension, and hypercholesterolemia, as well as radiation dose to the coronary artery origins, were prognostic factors. In the group of patients with LTL measurements, hypertension and LTL were the only independent risk factors. Conclusions: The findings suggest that CCTA can identify asymptomatic individuals at risk of acute coronary artery disease who might require either preventive or curative measures. Conventional risk factors and the radiation dose to coronary artery origins were independent prognostic factors. The prognostic value of LTL needs further investigation.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Risk Factors for Brain Metastases in Locally Advanced Non-Small Cell Lung Cancer With Definitive Chest Radiation

Purpose: We intended to identify risk factors that affect brain metastases (BM) in patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving definitive radiation therapy, which may guide the choice of selective prevention strategies. Methods and Materials: The characteristics of 346 patients with stage III NSCLC treated with thoracic radiation therapy from January 2008 to December 2010 in our institution were retrospectively reviewed. BM rates were analyzed by the Kaplan-Meier method. Multivariate Cox regression analysis was performed to determine independent risk factors for BM. Results: The median follow-up time was 48.3 months in surviving patients. A total of 74 patients (21.4%) experienced BM at the time of analysis, and for 40 (11.7%) of them, the brain was the first site of failure. The 1-year and 3-year brain metastasis rates were 15% and 28.1%, respectively. In univariate analysis, female sex, age ≤60 years, non-squamous cell carcinoma, T3-4, N3, >3 areas of lymph node metastasis, high lactate dehydrogenase and serum levels of tumor markers (CEA, NSE, CA125) before treatment were significantly associated with BM (P<.05). In multivariate analysis, age ≤60 years (P=.004, hazard ratio [HR] = 0.491), non-squamous cell carcinoma (P=.000, HR=3.726), NSE >18 ng/mL (P=.008, HR=1.968) and CA125 ≥ 35 U/mL (P=.002, HR=2.129) were independent risk factors for BM. For patients with 0, 1, 2, and 3 to 4 risk factors, the 3-year BM rates were 7.3%, 18.9%, 35.8%, and 70.3%, respectively (P<.001). Conclusions: Age ≤60 years, non-squamous cell carcinoma, serum NSE >18 ng/mL, and CA125 ≥ 35 U/mL were independent risk factors for brain metastasis. The possibilities of selectively using prophylactic cranial irradiation in higher-risk patients with LA-NSCLC should be further explored in the future.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Simple Factors Associated With Radiation-Induced Lung Toxicity After Stereotactic Body Radiation Therapy of the Thorax: A Pooled Analysis of 88 Studies

Purpose: To study the risk factors for radiation-induced lung toxicity (RILT) after stereotactic body radiation therapy (SBRT) of the thorax. Methods and Materials: Published studies on lung toxicity in patients with early-stage non–small cell lung cancer (NSCLC) or metastatic lung tumors treated with SBRT were pooled and analyzed. The primary endpoint was RILT, including pneumonitis and fibrosis. Data of RILT and risk factors were extracted from each study, and rates of grade 2 to 5 (G2+) and grade 3 to 5 (G3+) RILT were computed. Patient, tumor, and dosimetric factors were analyzed for their correlation with RILT. Results: Eighty-eight studies (7752 patients) that reported RILT incidence were eligible. The pooled rates of G2+ and G3+ RILT from all 88 studies were 9.1% (95% confidence interval [CI]: 7.15-11.4) and 1.8% (95% CI: 1.3-2.5), respectively. The median of median tumor sizes was 2.3 (range, 1.4-4.1) cm. Among the factors analyzed, older patient age (P=.044) and larger tumor size (the greatest diameter) were significantly correlated with higher rates of G2+ (P=.049) and G3+ RILT (P=.001). Patients with stage IA versus stage IB NSCLC had significantly lower risks of G2+ RILT (8.3% vs 17.1%, odds ratio = 0.43, 95% CI: 0.29-0.64, P<.0001). Among studies that provided detailed dosimetric data, the pooled analysis demonstrated a significantly higher mean lung dose (MLD) (P=.027) and V20 (P=.019) in patients with G2+ RILT than in those with grade 0 to 1 RILT. Conclusions: The overall rate of RILT is relatively low after thoracic SBRT. Older age and larger tumor size are significant adverse risk factors for RILT. Lung dosimetry, specifically lung V20 and MLD, also significantly affect RILT risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

A fast marching algorithm for the factored eikonal equation

The eikonal equation is instrumental in many applications in several fields ranging from computer vision to geoscience. This equation can be efficiently solved using the iterative Fast Sweeping (FS) methods and the direct Fast Marching (FM) methods. However, when used for a point source, the original eikonal equation is known to yield inaccurate numerical solutions, because of a singularity at the source. In this case, the factored eikonal equation is often preferred, and is known to yield a more accurate numerical solution. One application that requires the solution of the eikonal equation for point sources is travel time tomography. This inverse problem may be formulated using the eikonal equation as a forward problem. While this problem has been solved using FS in the past, the more recent choice for applying it involves FM methods because of the efficiency in which sensitivities can be obtained using them. However, while several FS methods are available for solving the factored equation, the FM method is available only for the original eikonal equation. In this paper we develop a Fast Marching algorithm for the factored eikonal equation, using both first and second order finite-difference schemes. Our algorithm follows the same lines as the original FM algorithm and requires the same computational effort. In addition, we show how to obtain sensitivities using this FM method and apply travel time tomography, formulated as an inverse factored eikonal equation. Numerical results in two and three dimensions show that our algorithm solves the factored eikonal equation efficiently, and demonstrate the achieved accuracy for computing the travel time. We also demonstrate a recovery of a 2D and 3D heterogeneous medium by travel time tomography using the eikonal equation for forward modeling and inversion by Gauss–Newton.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Clean and Convenient Tessellations for Number Counting Jastrow Factors

We introduce a basis of counting functions that, by cleanly tessellating three-dimensional space, allows real space number counting Jastrow factors to be straightforwardly applied to general molecular situations. Here, by exerting direct control over electron populations in local regions of space and encoding pairwise correlations between these populations, these Jastrow factors allow even very simple reference wave functions to adopt nodal surfaces well suited to many strongly correlated settings. Being trivially compatible with traditional Jastrow factors and diffusion Monte Carlo and having the same cubic per-sample cost scaling as a single determinant trial function, these Jastrow factors thus offer a powerful new route to the simultaneous capture of weak and strong electron correlation effects in a wide variety of molecular and materials settings. In multiple strongly correlated molecular examples, we show that even when paired with the simplest possible single determinant reference, these Jastrow factors allow quantum Monte Carlo to out-perform coupled cluster theory and approach the accuracy of traditional multireference methods.

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

A new method to construct a horizontal resolution-dependent wind speed adjustment factor for tropical cyclones in global climate model simulations

A new method to construct a horizontal resolution-dependent wind speed adjustment factor for evaluating tropical cyclones (TCs) in global climate models (GCMs) is presented here. In contrast to the previous studies that used idealized axisymmetric wind fields, this study analyzes 48 hours of 10-second surface wind fields from 1-km TC simulations. The adjustment factor is derived from filtering the simulated TC wind fields onto various horizontal grid spacings typical of those used in GCMs. The new adjustment factor leads to TCs with greater intensity than the existing adjustment factors for horizontal grid spacings smaller than 30 km. This difference is attributed to more realistic wind fields in the TC simulations that contain highly asymmetric, localized patches of higher wind speeds instead of axisymmetric wind fields. Applying the new adjustment factor to select GCM simulations suggests the common interpretation of low-intensity bias in GCM-simulated TCs might be slightly exaggerated.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

All-dielectric metasurface analogue of electromagnetically induced transparency [High Quality Factor Fano-Resonant All-Dielectric Metamaterials]

Fano-resonant plasmonic metamaterials and nanostructures have become a major focus of the nanophotonics fields over the past several years due their ability to produce high quality factor (Q-factor) resonances. The origin of such resonances is the interference between a broad and narrow resonance, ultimately allowing suppression of radiative damping. However, Fano-resonant plasmonic structures still suffer non-radiative damping due to Ohmic loss, ultimately limiting the achievable Q-factors to values less than ~10. Here, we report experimental demonstration of Fano-resonant silicon-based metamaterials that have a response that mimics the electromagnetically induced transparency (EIT) found in atomic systems. Due to extremely low absorption loss, a record-high quality factor (Q-factor) of 306 was experimentally observed. Furthermore, the unit cell of the metamaterial was designed with a feed-gap which results in strong local field enhancement in the surrounding medium resulting in strong light-matter interaction. This allows the metamaterial to serve as a refractive index sensor with a figure-of-merit (FOM) of 101, far exceeding the performance of previously demonstrated localized surface plasmon resonance sensors.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor

Low-dimensional materials have recently attracted much interest as thermoelectric materials because of their charge carrier confinement leading to thermoelectric performance enhancement. Carbon nanotubes are promising candidates because of their one-dimensionality in addition to their unique advantages such as flexibility and light weight. However, preserving the large power factor of individual carbon nanotubes in macroscopic assemblies has been challenging, primarily due to poor sample morphology and a lack of proper Fermi energy tuning. Here, we report an ultrahigh value of power factor (14± 5 mW m -1 K -2 ) for macroscopic weavable fibers of aligned carbon nanotubes with ultrahigh electrical and thermal conductivity. The observed giant power factor originates from the ultrahigh electrical conductivity achieved through excellent sample morphology, combined with an enhanced Seebeck coefficient through Fermi energy tuning. We fabricate a textile thermoelectric generator based on these carbon nanotube fibers, which demonstrates high thermoelectric performance, weavability, and scalability. The giant power factor we observe make these fibers strong candidates for the emerging field of thermoelectric active cooling, which requires a large thermoelectric power factor and a large thermal conductivity at the same time.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Quantum Annealing for Prime Factorization

We have developed a framework to convert an arbitrary integer factorization problem to an executable Ising model by first writing it as an optimization function then transforming the k-bit coupling (k ≥ 3) terms to quadratic terms using ancillary variables. Our resource-efficient method uses O (log 2 ( N )) binary variables (qubits) for finding the factors of an integer N. We present how to factorize 15, 143, 59989, and 376289 using 4, 12, 59, and 94 logical qubits, respectively. This method was tested using the D-Wave 2000Q for finding an embedding and determining the prime factors for a given composite number. The method is general and could be used to factor larger integers as the number of available qubits increases, or combined with other ad hoc methods to achieve better performances for specific numbers.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Structure of the human factor VIII C2 domain in complex with the 3E6 inhibitory antibody

Blood coagulation factor VIII is a glycoprotein cofactor that is essential for the intrinsic pathway of the blood coagulation cascade. Inhibitory antibodies arise either spontaneously or in response to therapeutic infusion of functional factor VIII into hemophilia A patients, many of which are specific to the factor VIII C2 domain. The immune response is largely parsed into “classical” and “non-classical” inhibitory antibodies, which bind to opposing faces cooperatively. In this study, the 2.61 Å resolution structure of the C2 domain in complex with the antigen-binding fragment of the 3E6 classical inhibitory antibody is reported. The binding interface is largely conserved when aligned with the previously determined structure of the C2 domain in complex with two antibodies simultaneously. Further inspection of the B factors for the C2 domain in various X-ray crystal structures indicates that 3E6 antibody binding decreases the thermal motion behavior of surface loops in the C2 domain on the opposing face, thereby suggesting that cooperative antibody binding is a dynamic effect. Furthermore, understanding the structural nature of the immune response to factor VIII following hemophilia A treatment will help lead to the development of better therapeutic reagents.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Optimization of the Jastrow factor using the random-phase approximation and a similarity-transformed Hamiltonian: Application to band-structure calculation for some semiconductors and insulators

Based on the random-phase approximation and the transcorrelated (TC) method, we optimize the Jastrow factor together with one-electron orbitals in the Slater determinant in the correlated wave function with a new scheme for periodic systems. The TC method is one of the promising wave function theories for first-principles electronic structure calculation, where the many-body wave function is approximated as a product of a Slater determinant and a Jastrow factor, and the Hamiltonian is similarity-transformed by the Jastrow factor. Using this similarity-transformed Hamiltonian, we can optimize the one-electron orbitals without evaluating 3N-dimensional integrations for the N-electron system. In contrast, optimization of the Jastrow factor within the framework of the TC method is computationally much more expensive and has not been performed for solid-state calculations before. In this study, we also benefit from the similarity-transformation in optimizing the Jastrow factor. Our optimization scheme is tested in applications to some solids from narrow-gap semiconductors to wide-gap insulators, and it is verified that the band gap of a wide-gap insulator and the lattice constants of some solids are improved by this optimization with reasonable computational cost.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Bioaccumulation factor of {sup 137}Cs in some marine biotas from West Bangka Indonesia

Radionuclides may be released from nuclear facilities to the marine environment. Concentrations of radionuclides within marine biotic systems can be influenced by a number of factors, including the type of biota, its source, the radionuclide, and specific characteristics of the sampled specimens and the marine environment (salinity, etc.). The bioconcentration factor for a marine organism is the ratio of the concentration of a radionuclide in that organism to the concentration found in its marine water environment - under conditions of equilibrium. Information on the bioaccumulation of Cs-137 in marine organisms is required to risk assessment evaluates the potential risks to human health. Bioaccumulation of Cs was investigated in marine biota from west Bangka such as Marine cat fish (Arius thalassinus), Baramundi (Lates calcarifer), Mackerel (Scomberomorus commerson), Striped eel catfish (Plotosus lineatus), eel tailed fish (Euristhmus microceps), Yellowtail fusilier (Caesio erythrogaster), Coastal crab (Scylla sp), White shrimp (Penaeus merguiensis) and marine bivalve mollusk (Anadara granosa). Muscle of these marine biota, sediments and water were assayed for Cs-137 by HPGe gamma spectrometer. The bioaccumulation factor for fishes were calculated by ratio of concentration Cs-137 in muscle biota to the its concentration in water. The bioaccumulation factor for mollusks were calculates by ratio of concentration Cs-137 in muscle biota to the its concentration in sediments. The bioaccumulation factor were range 4.99 to 136.34.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Verification of maximum radial power peaking factor due to insertion of FPM-LEU target in the core of RSG-GAS reactor

Verification of Maximum Radial Power Peaking Factor due to insertion of FPM-LEU target in the core of RSG-GAS Reactor. Radial Power Peaking Factor in RSG-GAS Reactor is a very important parameter for the safety of RSG-GAS reactor during operation. Data of radial power peaking factor due to the insertion of Fission Product Molybdenum with Low Enriched Uranium (FPM-LEU) was reported by PRSG to BAPETEN through the Safety Analysis Report RSG-GAS for FPM-LEU target irradiation. In order to support the evaluation of the Safety Analysis Report incorporated in the submission, the assessment unit of BAPETEN is carrying out independent assessment in order to verify safety related parameters in the SAR including neutronic aspect. The work includes verification to the maximum radial power peaking factor change due to the insertion of FPM-LEU target in RSG-GAS Reactor by computational method using MCNP5and ORIGEN2. From the results of calculations, the new maximum value of the radial power peaking factor due to the insertion of FPM-LEU target is 1.27. The results of calculations in this study showed a smaller value than 1.4 the limit allowed in the SAR.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

Mechanism and influencing factors on critical pulse width of oil-immersed polymer insulators under short pulses

The critical pulse width (τ{sub c}) is a pulse width at which the surface flashover threshold (E{sub f}) is equal to the bulk breakdown threshold (E{sub BD}) for liquid-polymer composite insulation systems, which is discovered by Zhao et al. [Annual Report Conference on Electrical Insulation and Dielectric Phenomena (IEEE Dielectrics and Electrical Insulation Society, Shenzhen, China, 2013), Vol. 2, pp. 854–857]. In this paper, the mechanism of τ{sub c} is interpreted in perspective of the threshold and the time delay (t{sub d}) of surface flashover and bulk breakdown, respectively. It is found that two changes appear as the pulse width decreases which are responsible for the existence of τ{sub c}: (1) E{sub BD} is lower than E{sub f}; (2) t{sub d} of bulk breakdown is shorter than t{sub d} of surface flashover. In addition, factors which have influences on τ{sub c} are investigated, such as the dielectric type, the insulation length, the dielectric thickness, the dielectrics configuration, the pulse number, and the liquid purity. These influences of factors are generalized as three types if τ{sub c} is expected to increase: (1) factors causing E{sub BD} to decrease, such as increasing the pulse number or employing a dielectric of lower E{sub BD}; (2) factors causing E{sub f} to increase, such as complicating the insulator's configuration or increasing the liquid purity; (3) factors causing E{sub BD} and E{sub f} to increase together, but E{sub f} increases faster than E{sub BD}, such as decreasing the dielectric thickness or the insulation length. With the data in references, all the three cases are verified experimentally. In the end, a general method based on τ{sub c} for solid insulation design is presented and the significance of τ{sub c} on solid insulation design and on solid demolition are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Prime factorization using magnonic holographic devices

Determining the prime factors of a given number $N$ is a problem that requires super-polynomial time for conventional digital computers. A polynomial-time algorithm was invented by Shor for quantum computers. In this paper, we present experimental data that demonstrate prime factorization using spin-wave interference but without quantum entanglement. Prime factorization includes three major steps. First, a general-type computer calculates the sequence of numbers m k mod($N$), where $N$ is the number to be factorized, m is a randomly chosen positive integer, and k = 1, 2, 3, 4, 5, 6…. Next, the period of the calculated sequence $r$ is determined by exploiting spin-wave interference. Finally, the general-type computer determines the primes based on the obtained $r$. The experiment for period finding was conducted on a six-terminal Y 3 Fe 2 (FeO 4 ) 3 device. We chose number 15 for testing and determined its primes using a sequence of measurements. The obtained experimental data for a micrometer-sized prototype aimed to demonstrate the benefits of using spin-wave devices to solve complex computational problems. Scalability is one of the major strengths inherent in this type of wave-based device, which may provide a route to nanometer-sized logic circuits. We discuss the physical and technological limitations of this approach, which define the maximum size of N and the computational speed. Although this classical approach cannot compete with the quantum algorithm in terms of efficiency, magnonic holographic devices can potentially be used as complementary logic units aimed at speeding up prime factorization for classical computers.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Spectral dispersion of the linewidth enhancement factor and four wave mixing conversion efficiency of an InAs/GaAs multimode quantum dot laser

The spectral dependence of the linewidth enhancement factor (αH-factor) of a multimode InAs/GaAs quantum dot laser is analyzed. Amplified spontaneous and high-frequency modulation methods are used to experimentally retrieve the αH-factor of each longitudinal mode below and above the threshold. A dispersion of the αH-factor is unlocked across the entire optical spectrum, which is further illustrated in the context of four wave mixing experiments. The results show that the induced conversion efficiency is increased at lasing wavelengths where the linewidth enhancement is lower. These results highlight the importance of carefully monitoring the linewidth enhancement factor in quantum dot lasers especially for frequency combs and mode-locking applications in future optical communication systems.

Ding, Shihao (ORCID:0000000346416944)↗
DOE OSTI2022

Self-organized magnetic equilibria in tokamak plasmas with very low edge safety factor

Tokamak plasmas often exhibit self-organizing behavior in which internal modes shape the toroidal current density profile, a common example being the sawtooth instability. However, such behavior has not been studied in detail for edge safety factor below 2 due to disruptive kink instabilities that typically prevent operation in this regime. Now, steady tokamak plasmas with an edge safety factor down to 0.8 have been created in the Madison Symmetric Torus, where disruptions are prevented due to a thick, conductive wall and a feedback power supply that sustains the plasma current. Internal measurements and nonlinear magnetohydrodynamic modeling reveal a family of safety factor profiles with a central value clamped near unity as the edge safety factor decreases, indicating current profile broadening through a relaxation process. Furthermore, as the safety factor decreases, the magnetic fluctuations become irregular, and the electron energy confinement time decreases.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗