Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Multiple”

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 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

PET Imaging Study of S1PR1 Expression in a Rat Model of Multiple Sclerosis

Upregulation of sphingosine-1-phosphate receptor 1 (S1PR1) expression in multiple sclerosis (MS) lesions is associated with neuroinflammatory response. This study investigated the correlation between neuroinflammation and S1PR1 expression in the spinal cord of an experimental autoimmune encephalomyelitis (EAE) rat model of MS, using the S1PR1 positron emission tomography (PET) radiotracer [11C]TZ3321. MicroPET imaging studies of [11C]TZ3321 were performed to measure uptake of [11C]TZ3321 in the spinal cord of EAE rats. Immunohistochemical staining was performed to confirm the overexpression of S1PR1 and other inflammatory biomarkers. MicroPET imaging demonstrated a 20–30 % increase in [11C]TZ3321 uptake in the lumbar spinal cord of EAE rats versus sham controls at 35–60 min post injection. The increased uptake of [11C]TZ3321 was correlated with the overexpression of S1PR1 in the lumbar spinal cord of EAE rats that was confirmed by immunohistochemical staining. Upregulated S1PR1 expression was associated with glial cell activation and immune cell infiltration. MicroPET imaging modality with a specific radioligand [11C]TZ3321 is able to assess the expression of S1PR1 in EAE rat lumbar spinal cord. This may provide a new approach to the assessment of neuroinflammatory response in MS and other inflammatory diseases.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Effect of oxidation on the release of multiple metals from industrially polluted sediments and synchrotron-based evidence of Cu–S dynamic association

Disposal operations for industrially polluted sediments are usually accompanied by disturbance and resuspension, which can induce metal remobilization and secondary pollution. Evaluating the risk of metal release under various redox conditions is fundamental for predicting contaminant mobilization and guiding remediation measures. An abandoned oxidation pond, Yanjia Lake, China, was selected as a typical industrially polluted site. Re-suspension experiments were carried out by mixing polluted sediments with lake water under oxic or anoxic conditions, then investigating the effect of oxidation conditions on the release of multiple metals. Metal concentrations and aqueous chemistry in the overlying water were monitored. Synchrotron-based methods, including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were used to characterize oxidation states and coordination conditions of metals in sediments. The release of metals, including Cr, Co, Ni, Cu, Zn, Se, Mo, Sn, Cd, and Pb, was enhanced under oxic vs. anoxic conditions. The XANES analysis revealed that elevated Cr and Zn concentrations under oxic conditions likely resulted from the oxidation of Cr(III) and oxidizing dissolution of ZnS, respectively. K-edge Cu XANES, S XANES, and Cu EXAFS analyses reconstructed the Cu–S association, indicating that S-related oxidation promoted Cu release and Cu–O partly replaced Cu–S in the sediment after a 7-day oxic treatment. The release of most metals was promoted under oxic conditions, resulting from the oxidation of sulfides and metals as indicated by aqueous and synchrotron-based evidence. The risk of secondary pollution is greatly enhanced under oxic conditions, which suggests that measures should be taken to minimize the redox disturbance during sediment remediation. This information can guide the management of sediments in Yanjia Lake and other contaminated sites with similar properties.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows

Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu 6 Sn 5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu 6 Sn 5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu 6 Sn 5 observed, while in the melt spun alloy, Cu 6 Sn 5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu 6 Sn 5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. As a result, the reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu 6 Sn 5 was maintained for both alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effects of Multiple Rejuvenation Cycles on Mechanical Properties and Microstructure of IN-738 Superalloy

The scope of this work is to show the effects of multiple applications of a rejuvenation treatment studied for IN-738 on both the microstructure and the mechanical properties of the creep-damaged superalloy and to check the recovery obtained after one and two rejuvenation cycles through creep and tensile tests, whose results will be compared with the performance of the virgin material. This work will show that this rejuvenation treatment is able to recover the microstructure of creep-damaged specimens after one and two applications and that the mechanical properties of the rejuvenated alloy are very similar to the virgin material even after two rejuvenation cycles.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Residual Stress Distribution and Microstructure of a Multiple Laser-Peened Near-Alpha Titanium Alloy

Laser peening without coating (LPwC) was performed on a Ti-2.5 Cu alloy with multiple passes (1, 3 and 5), using a Nd:YAG laser (1064 nm) at a constant overlap rate of 70% and power density of 6.7 GW cm{sup −2}. Hardness and residual stress profiles indicated thermal softening near the surface (< 100 μm) and bulk softening due to adiabatic heating. Maximum hardness (235 HV at 500 μm) and maximum residual stress (− 890 MPa at 100 μm) were observed for LPwC with 1 pass. Surface roughness and surface 3-D topography imaging showed that the surface roughness increased with the increase in the number of passes. XRD results indicated no significant β phases. However, peak shifts, broadening and asymmetry were observed and interpreted based on dislocation activity. Microstructures indicated no melting or resolidification or refinement of grains at the surface. Twin density was found to increase with the increase in the number of passes.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Multiple Local Repairs on Microstructure and Mechanical Properties of T24 Steel Welded Joint

The effect of multiple local repairs on the microstructure and mechanical properties of the T24 steel welded joints was studied. T24 steel tubes were butt-welded by the GTAW method. Peripheral welded joints were made in four locations of the tube. In order to simulate the repair procedure, the welds were cut off from the root and the first local repair was performed. Other two local repairs were carried out in the same way. After each local repair, the microstructure and mechanical properties of the joints were evaluated. The results of the mechanical tests demonstrate that only two local repairs can be performed on the T24 steel peripheral welded joint. After the third local repair, impact energy of the welded joint was lower than required value, which is attributed to the coarser martensite and the coarser carbide precipitates formed in the heat-affected zone, compared with the weld metal.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of ABCB1 polymorphisms on the pharmacokinetics and toxicity of lenalidomide in patients with multiple myeloma

Individual diversity in plasma concentrations of lenalidomide occurs despite dosage modifications based on creatinine clearance (CCr), which can lead to unexpected toxicity. We have previously identified a cutoff value of area under the concentration–time curve (AUC{sub 0–24}) for lenalidomide to avoid severe toxicity. Here, we investigated the association between ABCB1 polymorphisms and pharmacokinetics of lenalidomide in patients with multiple myeloma (MM) treated with lenalidomide and dexamethasone. Plasma concentrations of lenalidomide were analyzed using liquid chromatography–tandem mass spectrometry. Genotyping for ABCB1 1236C>T, 2677G>A/T, and 3435C>T polymorphisms was performed, and the effects of ABCB1 polymorphisms on AUC{sub 0–24} for lenalidomide were compared in 36 patients with MM who were administered lenalidomide according to the drug label based on CCr. Genotyping analysis showed that although there were no differences in AUC{sub 0–24} in 1236C>T and 2677G>A/T polymorphisms. AUC{sub 0–24} was significantly higher in patients with the T allele of 3435C>T (n = 15) than in those without (n = 21) (median 6324.6 ng h/mL vs. 2857.4 ng h/mL, p = 0.028). The AUC{sub 0–24} value exceeded the aforementioned cutoff value in 95% of the patients with the T allele of 3435C>T but in 60% with C/C genotype (p = 0.013). Multivariate logistic analysis confirmed the significance of T allele of ABCB1 3435C>T as a factor due to which the AUC{sub 0–24} cutoff value was exceeded (hazard ratio of 15.0, p = 0.019). We show that lenalidomide pharmacokinetics is influenced by the ABCB1 3435C>T polymorphism, which could be useful to individualize dosage design and reduce unexpected toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Heterogeneities at multiple length scales in 2D layered materials: From localized defects and dopants to mesoscopic heterostructures

Two-dimensional (2D) materials hold great promise for applications in optoelectronics, quantum information science, and energy conversion due to their remarkable properties imbued by their physical characteristics. Although heterogeneities in their intrinsic structure are the major challenges limiting their synthesis and predictable properties, they also provide a pathway to controllably tune the properties and broaden the potential of 2D materials. Heterogeneities that can be tailored, including defects, dopants, strain, edges, and layer stackings offer transformative opportunities in heterogeneous 2D materials through the introduction of novel properties for technological applications. This article provides a review of recent progress in studying heterogeneities in 2D materials. The review uses examples from our work to develop a strategy to understand the heterogeneities across multiple length scales to link the effect of heterogeneity at the nanoscale with the macroscale properties of 2D materials. We describe specific types of heterogeneities and explore novel synthesis and processing methods for their controlled production with example of the potential impact and applications enabled by their intriguing properties. Finally, we provide a perspective on how to extend the range of tunable properties through further engineering the heterogeneities in 2D materials.

2D materials↗
DOE OSTI2018

Asynchronously parallel optimization solver for finding multiple minima

This paper proposes and analyzes an asynchronously parallel optimization algorithm for finding multiple, high-quality minima of nonlinear optimization problems. Our multistart algorithm considers all previously evaluated points when determining where to start or continue a local optimization run. Theoretical results show that, under certain assumptions, the algorithm almost surely starts a finite number of local optimization runs and identifies, or has a single local optimization run converging to, every minimum. The algorithm is applicable to general optimization settings, but our numerical results focus on the case when derivatives are unavailable. In numerical tests, a PYTHON implementation of the algorithm is shown to yield good approximations of many minima (including a global minimum), and this ability scales well with additional resources. Our implementation’s time to solution is shown also to scale well even when the time to evaluate the function evaluation is highly variable.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Investigating the age distribution of fracture discharge using multiple environmental tracers, Bedrichov Tunnel, Czech Republic

We investigated the transit time distribution (TTD) of discharge collected from fractures in the Bedrichov Tunnel, Czech Republic, using lumped parameter models and multiple environmental tracers. We then utilize time series of δ 18 O, δ 2 H and 3 H along with CFC measurements from individual fractures in the Bedrichov Tunnel of the Czech Republic to investigate the TTD, and the uncertainty in estimated mean travel time in several fracture networks of varying length and discharge. We also compare several TTDs, including the dispersion distribution, the exponential distribution, and a developed TTD which includes the effects of matrix diffusion. The effect of seasonal recharge is explored by comparing several seasonal weighting functions to derive the historical recharge concentration. We identify best fit mean ages for each TTD by minimizing the error-weighted, multi-tracer χ2 residual for each seasonal weighting function. We use this methodology to test the ability of each TTD and seasonal input function to fit the observed tracer concentrations, and the effect of choosing different TTD and seasonal recharge functions on the mean age estimation. We find that the estimated mean transit time is a function of both the assumed TTD and seasonal weighting function. Best fits as measured by the χ2 value were achieved for the dispersion model using the seasonal input function developed here for two of the three modeled sites, while at the third site, equally good fits were achieved with the exponential model and the dispersion model and our seasonal input function. The average mean transit time for all TTDs and seasonal input functions converged to similar values at each location. The sensitivity of the estimated mean transit time to the seasonal weighting function was equal to that of the TTD. These results indicated that understanding seasonality of recharge is at least as important as the uncertainty in the flow path distribution in fracture networks and that unique identification of the TTD and mean transit time is difficult given the uncertainty in the recharge function. But, the mean transit time appears to be relatively robust to the structural model uncertainty. The results presented here should be applicable to other studies using environmental tracers to constrain flow and transport properties in fractured rock systems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

High-performance n-Type Polymers Based on Multiple Electron-withdrawing Groups Decorated ( E )-1,2-Di(thiophen-2-yl)ethene Building Blocks

The performance of n-type conjugated polymers lags far behind that of p-type polymers, which significantly restricts the development of organic electronics. The (E)-1,2-di(thiophen-2-yl)ethene (TVT) unit, owing to its unique advantages, has been widely applied in the design of p-type polymer semiconductors. Previous studies have demonstrated that introducing electron-withdrawing groups can lower the frontier orbital energy levels of polymers and enhance electron injection/transporting capabilities. Based on this, we proposed incorporating multiple electronwithdrawing groups, such as amide groups, fluorine atoms, and cyano groups, into the polymer backbones of TVT-based polymer to facilitate the electron transport. Here, we successfully designed and synthesized the polymers TVTDA-4FTVT and TVTDA-2F2CNTVT. Both polymers exhibited low frontier orbital energy levels. Due to its significantly higher crystallization tendency and favorable intermolecular packing structure, the organic field-effect transistor (OFET) device based on TVTDA-4FTVT demonstrated an electron mobility one order of magnitude higher than that of TVTDA-2F2CNTVT. TVTDA-4FTVT showed the highest electron mobility of 0.87 cm 2 ·V −1 ·s −1 , while TVTDA-2F2CNTVT exhibited the highest electron mobility of 0.049 cm 2 ·V −1 ·s −1 . Owing to its deeper lowest unoccupied molecular orbital (LUMO) level, the OFET devices based on TVTDA-2F2CNTVT showed good air stability after being placed in a natural environment for 15 d.

36 MATERIALS SCIENCE↗
DOE OSTI2018

An (R, S)-norm fuzzy information measure with its applications in multiple-attribute decision-making

In this paper, we introduce a quantity measure which is called (R, S)-norm entropy and discuss some of its major properties with Shannon’s and other entropies in the literature. Based on this (R, S)-norm entropy, we have proposed a new (R, S)-norm fuzzy information measure and discussed its validity and properties. Further, we have given its comparison with other fuzzy information measures to prove its effectiveness. Attribute weights play an important role in multiple-attribute decision-making problems. In the present communication, two methods of determining the attribute weights are introduced. First is the case when the information regarding attribute weights is incompletely known or completely unknown and second is when we have partial information about attribute weights. For the first case, the extension of ordinary entropy weight method is used to calculate attribute weights and minimum entropy principle method based on solving a linear programming model is used in the second case. Finally, two methods are explained through numerical examples.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Oxidation mechanism in a refractory multiple-principal-element alloy at high temperature

Refractory multiple-principal-element alloys (RMPEAs) are promising structural materials to enable increased power efficiency in high-temperature oxidation environments, but the oxidation behavior and microstructures of the oxides, especially at the beginning of the oxidation, have received limited attention. Here, the oxidation mechanism in an equimolar W-Mo-Ta-Nb-V was investigated at 1300 °C and compared with the equimolar W-Mo-Ta-Nb alloy without V. The oxide scale on WMoTaNbV after 1 min exposure is shown to be composed of a degradation layer at the interface of the alloy/oxide, an initial oxide transition layer, followed by the main phase aggregate oxide layer, and an outermost oxide layer. At the early stage of oxidation, the absorption of oxygen by the RMPEA substrate forms a solid solution. Vanadium accelerates the initial degradation process as it forms VO. The initial oxidation-induced degradation of RMPEA follows a sequence governed by the free energy change accompanied by local element segregation. Liquid V-Mo oxides aggregate in the intermediate oxide layer. The inward growth of the oxide scale is controlled by the local composition changes, the orientation of the substrate, the crystal structure, and physical properties such as melting points of the oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Langevin equation with multiplicative white noise: Transformation of diffusion processes into the Wiener process in different prescriptions

A Langevin equation with multiplicative white noise and its corresponding Fokker-Planck equation are considered in this work. From the Fokker-Planck equation a transformation into the Wiener process is provided for different orders of prescription in discretization rule for the stochastic integrals. A few applications are also discussed. - Highlights: Black-Right-Pointing-Pointer Fokker-Planck equation corresponding to the Langevin equation with mul- tiplicative white noise is presented. Black-Right-Pointing-Pointer Transformation of diffusion processes into the Wiener process in different prescriptions is provided. Black-Right-Pointing-Pointer The prescription parameter is associated with the growth rate for a Gompertz-type model.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Study of the all orders multiplicative renormalizability of a local confining quark action in the Landau gauge

The inverse of the Faddeev–Popov operator plays a pivotal role within the Gribov–Zwanziger approach to the quantization of Euclidean Yang–Mills theories in Landau gauge. Following a recent proposal (Capri et al., 2014), we show that the inverse of the Faddeev–Popov operator can be consistently coupled to quark fields. Such a coupling gives rise to a local action while reproducing the behaviour of the quark propagator observed in lattice numerical simulations in the non-perturbative infrared region. By using the algebraic renormalization framework, we prove that the aforementioned local action is multiplicatively renormalizable to all orders.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Effective field theories for superconducting systems with multiple Fermi surfaces

In this work we investigate the description of superconducting systems with multiple Fermi surfaces. For the case of one Fermi surface we re-obtain the result that the superconductor is more precisely described as a topological state of matter. Studying the case of more than one Fermi surface, we obtain the effective theory describing a time reversal symmetric topological superconductor. These results are obtained by employing a general procedure to construct effective low energy actions describing states of electromagnetic systems interacting with charges and defects. The procedure consists in taking into account the proliferation or dilution of these charges and defects and its consequences for the low energy description of the electromagnetic response of the system. We find that the main ingredient entering the low energy characterization of the system with more than one Fermi surface is a non-conservation of the canonical supercurrent triggered by particular vortex configurations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Multiple stable states and Dicke phase transition for two atoms in an optical cavity

We study in the present paper the multiple stable states of two different atoms in a single-mode quantum cavity by means of variational method. Eigenenergies and eigenstates are obtained analytically in the optical coherent state of cavity field. The ground state displays the known Dicke phase transition from the normal to superradiant phases at the critical value of atom–field coupling. The rich phase diagrams including the stable excited states are presented respectively for two atoms with different level spaces and atom–field couplings. By adjusting the ratios of two-atom couplings or level spaces, one atom can be in the normally populated state, while the other is in the inversely populated state. We also observe the stimulated radiation from the inversely populated state. Particularly, the normal and stimulated radiations are interchangeable respectively for two atoms. Moreover, the maximally entangled state can be generated with two identical atoms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Distributed biomass supply chain cost optimization to evaluate multiple feedstocks for a biorefinery

Conventional practices of siting all biomass preprocessing operations at the biorefinery is widely believed to be the most cost-effective solution for feedstock supply because of economies of scale. Yet, biomass preprocessing operations could be decentralized by moving the preprocessing operations to distributed biomass preprocessing centers, also known as “depots” located near biomass sources. We present a comparative case study with multiple biomass resources to analyze biorefinery feedstock supply logistics designs having distributed depots and a primary depot co-located with the biorefinery. A mixed-integer linear programming model was developed to simultaneously optimize feedstock sourcing decisions, and optimal preprocessing depot locations and size, utilizing biomass resources from agricultural residue, energy and municipal solid waste to meet carbohydrate specifications and feedstock demand for a biochemical conversion process. Findings from a case study in the US showed that a biorefinery could increase its feedstock supply draw area and supply volume by 57.3%, 177.4% respectively without increasing the feedstock delivered cost by adopting distributed depot-in the feedstock supply chain design. A distributed-depot-based supply chain can be more economical by selecting optimal mix of biomass resource, optimal siting and depot scales during feedstock supply chain design. The results from this study indicate that a biorefinery can utilize dynamic blending to meet the feedstock quality specifications as well as larger supply radius in the distributed depot-based supply chain design to access more available biomass to handle potential feedstock supply uncertainty.

09 BIOMASS FUELS↗