Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “COMPETITION”

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 1,135 records · Page 63

Why Vascular Surgeons and Interventional Radiologists Collaborate or Compete: A Look at Endovascular Stent Placements

PurposeTo understand how cultural differences between vascular surgeons (VSs) and interventional radiologists (IRs) affect their clinical decision making and inter-specialty relationships.MethodsTwenty-four conversational interviews were conducted with IRs and VSs about their approaches to patient care, views of their specialty and others, and solutions to any expressed concerns. Interview transcripts were systematically analyzed to identify and compare key themes according to the constructivist grounded theory and content analysis using NVivo 10 software. These data were supplemented with a retrospective analysis of 3658 endovascular stent placements performed at a large medical academic center over 11 years. Aggregate counts were divided by provider specialty, and trends were assessed via correlation coefficients.ResultsEndovascular stent placements were relatively equally divided between IR and VS over 11 years with some variability from placements by cardiology. IRs tend to lay claim to treatments as masters of procedures, whereas VSs base their claims on being masters of the treated diseases, leading to collaboration in some practices and bitter competition in others. The level of perceived competition was most associated with specialists’ awareness of and appreciation for specialty-specific values rather than differences in practice structure/reimbursement.ConclusionsUnderstanding cultural differences between IRs and VSs is imperative for fostering better collaboration to grow shared territory rather than competing for the same slice of the pie.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Plant Root Exudates Increase Methane Emissions through Direct and Indirect Pathways

The largest natural source of CH4 to the atmosphere is wetlands, which produce 20% to 50% of total global emissions. Vascular plants play a key role regulating wetland CH4 emissions through multiple mechanisms. They often contain aerenchymatous tissues which act as a diffusive pathway for CH4 to travel from the anoxic soil to the atmosphere and for O2 to diffuse into the soil and enable methanotrophy. Plants also exude carbon from their roots which stimulates microbial activity and fuels methanogenesis. This study investigated these mechanisms in a laboratory experiment utilizing rootboxes containing either Carex aquatilis plants, silicone tubes that simulated aerenchymatous gas transfer, or only soil as a control. CH4 emissions were far greater from planted boxes than from control boxes or simulated plants, indicating that the physical transport pathway of aerenchyma was of little importance when not paired with other effects of plant biology. Plants were exposed to 13CO2 at two time-points and subsequent enrichment of root tissue, rhizosphere soil, and emitted CH4 was used in an isotope mixing model to determine the proportion of plant-derived versus soil-derived carbon supporting methanogenesis. Results showed that carbon exuded by plants was converted to CH4 but that plants also increased emission of soil-derived carbon relative to the other experimental treatments. This result signifies that plants and root exudates altered the soil chemical environment and microbial community such that microbial utilization of soil carbon was increased (e.g. microbial priming) and/or oxidation of soil-derived CH4 was decreased (e.g., by microbial competition for oxygen).

methane, wetlands, microbial priming, root exudate↗

Food security under high bioenergy demand toward long-term climate goals

Bioenergy is expected to play an important role in the achievement of stringent climate-change mitigation targets requiring the application of negative emissions technology. Using a multi-model framework, we assess the effects of high bioenergy demand on global food production, food security, and competition for agricultural land. Various scenarios simulate global bioenergy demands of 100, 200, 300, and 400 exajoules (EJ) by 2100, with and without a carbon price. Six global energy-economy-agriculture models contribute to this study, with different methodologies and technologies used for bioenergy supply and greenhouse-gas mitigation options for agriculture. We find that the large-scale use of bioenergy, if not implemented properly, would raise food prices and increase the number of people at risk of hunger in many areas of the world. For example, an increase in global bioenergy demand from 200 to 300 EJ causes a -11% to +40% change in food crop prices and decreases food consumption from -45 to -2 kcal person -1 day -1 , leading to an additional 0 to 25 million people at risk of hunger compared with the case of no bioenergy demand (90th percentile range across models). This risk does not rule out the intensive use of bioenergy but shows the importance of its careful implementation, potentially including regulations that protect cropland for food production or for the use of bioenergy feedstock on land that is not competitive with food production.

54 ENVIRONMENTAL SCIENCES↗

What drives embodied carbon policy? A global perspective on adoption

Abstract Embodied carbon refers to the greenhouse gas emission associated with the lifecycle of buildings. Embodied carbon policies are critical for addressing the environmental impact of construction materials and advancing climate goals. Despite their importance, the adoption of embodied carbon policies has been limited globally, influenced by economic, environmental, institutional, and trade factors. This study employs structural equation modeling to analyze 37 countries, testing ten hypotheses across four categorical factors. The base model reveals the significant influence of environmental vulnerability and institutional frameworks on policy adoption, while robustness models confirm the critical role of trade dependencies and economic competitiveness in shaping national embodied carbon strategies. Findings underscore that countries with high climate vulnerability and strong institutional support are more likely to adopt embodied carbon policies. Conversely, trade-reliant nations face challenges balancing competitiveness and sustainability. Policy implications suggest the need for international collaboration to align trade policies with carbon reduction goals, targeted support for vulnerable nations, and the integration of embodied carbon considerations into existing climate frameworks. These results offer a roadmap for policymakers to design more effective and equitable embodied carbon policies, fostering global progress toward sustainable construction and decarbonization.

Hu, Ming (ORCID:0000000325831161)↗

Binding Studies of Isoxsuprine Hydrochloride to Calf Thymus DNA Using Multispectroscopic and Molecular Docking Techniques

In the present work, the interaction of Isoxsuprine (ISX) with Calf thymus DNA (ct-DNA) under physiological conditions (Tris–HCl buffer of pH 7.4) was investigated by using electronic absorption, circular dichroism, viscosity, electrochemical studies, fluorescence techniques, salt effect studies and computational studies. Competitive fluorimetric studies with Hoechst 33258 have shown that ISX exhibit the ability to displace the DNA-bound Hoechst 33258, indicating that it binds to ct-DNA in strong competition with Hoechst 33258 for the minor groove binding. Furthermore, the resulting data showed that ISX cannot displace methylene blue or acridine orange, which are the common intercalator molecules. The viscosity of ct-DNA solution was almost unchanged on addition of ISX and circular dichroism (CD) spectra of ct-DNA showed small changes in the presence of ISX which is in agreement with groove binding mode of interaction. Thus all above studies showed that the ISX drug binds to ct-DNA in a groove binding mode.The salt-effect studies showed the non-electrostatic nature of binding of ISX to ct-DNA. Moreover, molecular docking results support the above experimental data and suggest that ISX prefers to bind on the minor groove of ct-DNA.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Electron-Phonon Interaction in the Presence of Strong Coulomb Repulsion

We consider the Hubbard-Holstein model on a 2D tilted eight-site square lattice at quarter fillings having on-site (λ{sub 1}) and inter-site (λ{sub 2}) electron-phonon (EP) interactions and inter-site Coulomb repulsion (V ). Mobility of electrons decreases, and hence, localization of electrons is favored by λ{sub 1} as well as inter-site Coulomb repulsion in the non-interacting limit (U/t = 0.0). In the interacting case (U/t = 8.0), an initial delocalization effect observed due to the competition between on-site Coulomb repulsion and EP interaction λ{sub 1} though V favors localization. For smaller λ{sub 1}, the competition between λ{sub 2} and V increases the delocalization effect. As λ{sub 2} increases further, localization occurs. In the interacting case, localization occurs at much higher values of λ{sub 2} due to the additional delocalization effect of U. On-site (S0) and/or large bipolarons are formed with λ{sub 1} in the presence of V, and inter-site Coulomb repulsion effectively increases λ{sub 1}. Thus, V favors the formation of S0 bipolarons. However, the formation of S1 bipolarons is suppressed by inter-site Coulomb repulsion. An existence of critical λ{sub 2} = λ{sub 2c} is observed for the formation of on-site (S0) and neighboring-site (S1) bipolarons.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Effect of Tuning the Structure on the Optical and Magnetic Properties by Various Transition Metal Doping in ZnO/TM (TM = Fe, FeCo, Cr, and Mn) Thin Films

We have investigated in this work the physical, optical, electronic, and the magnetic behavior (Curie temperature, magnetic moment) of Zn.1-x.MxO (M = Fe 5%, Co 1%, Cr 5%, and Mn 5%), diluted magnetic semiconductors (DMSs). The samples were deposited on glass substrate by the spray pyrolysis technique, and the results of the x-ray diffraction (XRD) of the prepared substrates was used to prove the incorporation of the dopants into the ZnO lattice host; the ferromagnetic and the antiferromagnetic state competitions and their effects on the physical, magnetic, and optical properties, were investigated. The electronic structure and magnetic properties of transition metal (TM) defects, were investigated in detail, by using the Korringa–Kohn–Rostoker (KKR) method combined with the coherent potential approximation (CPA). As a result, doping by TM impurities induce the ferromagnetism with different competitions between the ferromagnetic and antiferromagnetic states, which affects the physical properties of the TM (Fe, Fe/Co, Cr, and Mn)-doped ZnO, with a Curie temperature closer to room-temperature ferromagnetic.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Water Footprints of Cassava- and Molasses-Based Ethanol Production in Thailand

The Thai government has been promoting renewable energy as well as stimulating the consumption of its products. Replacing transport fuels with bioethanol will require substantial amounts of water and enhance water competition locally. This study shows that the water footprint (WF) of molasses-based ethanol is less than that of cassava-based ethanol. The WF of molasses-based ethanol is estimated to be in the range of 1,510-1,990 L water/L ethanol, while that of cassava-based ethanol is estimated at 2,300-2,820 L water/L ethanol. Approximately 99% of the water in each of these WFs is used to cultivate crops. Ethanol production requires not only substantial amounts of water but also government interventions because it is not cost competitive. In Thailand, the government has exploited several strategies to lower ethanol prices such as oil tax exemptions for consumers, cost compensation for ethanol producers, and crop price assurances for farmers. For the renewable energy policy to succeed in the long run, the government may want to consider promoting molasses-based ethanol production as well as irrigation system improvements and sugarcane yield-enhancing practices, since molasses-based ethanol is more favorable than cassava-based ethanol in terms of its water consumption, chemical fertilizer use, and production costs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Persistent and transient cost efficiency—an application to the Swiss hydropower sector

Electricity prices on the European market have decreased significantly over the past few years, resulting in a deterioration of Swiss hydropower firms’ competitiveness and profitability. One option to improve the sector’s competitiveness is to increase cost efficiency. The goal of this study is to quantify the level of persistent and transient cost efficiency of individual firms by applying the generalized true random effects (GTRE) model introduced by Colombi et al. (Journal of Productivity Analysis 42(2): 123–136, 2014) and Filippini and Greene (Journal of Productivity Analysis 45(2): 187–196, 2016). Applying this newly developed GTRE model to a total cost function, the level of cost efficiency of 65 Swiss hydropower firms is analyzed for the period between 2000 and 2013. A true random effects specification is estimated as a benchmark for the transient level of cost efficiency. The results show the presence of both transient as well as persistent cost inefficiencies. The GTREM predicts the aggregate level of cost inefficiency to amount to 21.8% (8.0% transient, 13.8% persistent) on average between 2000 and 2013. These two components differ in interpretation and implication. From an individual firm’s perspective, the two types of cost inefficiencies might require a firm’s management to respond with different improvement strategies. The existing level of persistent inefficiency could prevent the hydropower firms from adjusting their production processes to new market environments. From a regulatory point of view, the results of this study could be used in the scope and determination of the amount of financial support given to struggling firms.

13 HYDRO ENERGY↗

Adversarial Ensemble Modeling of Multi-modal Mechanical Properties for Iron-Based Alloys

Mechanical properties of alloys are controlled by their microstructure; and microstructure evolution is controlled by internal and external stressors. Chemical complexity during the alloy processing may result in heterogeneity and observation of multimodal performance patterns. Thus, to ensure the desired performance of stressed components it is important to understand the origin and mechanisms of such behavior. Adversarial ensemble modeling was introduced here to explain multimodal mechanical properties of the iron-based alloys. The modeling results showed that the areas of a single mechanism predominance were contiguous across the alloy compositions clustered by similarity, with sharp and persistent boundaries separating the single-mechanism domains. The marginal compositions resulted in increased competition between the adversarial models but only led to the multimodal behavior when the competing models diverged. Transparency of the clustering method allowed explicit interpretation of the chemistries leading to such competition. The adversarial ensemble was interpreted through transition from ductile to brittle microstructure.

36 MATERIALS SCIENCE↗

Techno-Economic Evaluation of Cellulosic Ethanol Production Based on Pilot Biorefinery Data: a Case Study of Sweet Sorghum Bagasse Processed via L+SScF

Replacing fossil fuels with renewable fuels derived from lignocellulosic biomass can contribute to the mitigation of global warming and the economic development of rural communities. This will require lignocellulosic biofuels to become price competitive with fossil fuels. Techno-economic analyses can provide insights into which parts of the biofuel production process need to be optimized to reduce cost or energy use. Here, we used data obtained from a pilot biorefinery to model a commercial-scale biorefinery that processes lignocellulosic biomass to ethanol, with a focus on the minimum ethanol selling price (MESP). The process utilizes a phosphoric acid-catalyzed pre-treatment of sweet sorghum bagasse followed by liquefaction and simultaneous saccharification and co-fermentation (L+SScF) of hexose and pentose sugars by an engineered Escherichia coli strain. After validating a techno-economic model developed with the SuperPro Designer software for the conversion of sugarcane bagasse to ethanol by comparing it to a published Aspen Plus model, six different scenarios were modeled for sweet sorghum bagasse Under the most optimistic scenario, the ethanol can be produced at a cost close to the energy-equivalent price of gasoline. Aside from an increase in the price of gasoline, the gap between ethanol and gasoline prices could also be bridged by either a decrease in the cost of cellulolytic enzymes or development of value-added products from lignin.

Biofuel↗

Global stability of a diffusive and delayed virus infection model with general incidence function and adaptive immune response

In this paper, the dynamical behaviors for a five-dimensional virus infection model with diffusion and two delays which describes the interactions of antibody, cytotoxic T-lymphocyte (CTL) immune responses and a general incidence function are investigated. The reproduction numbers for virus infection, antibody immune response, CTL immune response, CTL immune competition and antibody immune competition, respectively, are calculated. By using the Lyapunov functionals and linearization methods, the threshold conditions on the global stability of the equilibria for infection-free, immune-free, antibody response, CTL response and antibody and CTL responses, respectively, are established if the space is assumed as homogeneous. When the space is inhomogeneous, the effects of diffusion, intracellular delay and production delay are obtained by the numerical simulations.

97 MATHEMATICS AND COMPUTING↗

Communities in energy transition: exploring best practices and decision support tools to provide equitable outcomes

Abstract The U.S. coal industry has been in a state of decline for the past decade, a trend ushered by flat electricity demand, increased regulatory pressure, and market competition from cost-competitive clean energy sources. The receding economic viability of the coal industry has been acutely felt by the communities with immediate economic ties to coal-fired generation. With the energy transition underway, the question of how to engage communities as stakeholders in the decision-making process and address their needs through an equitable and just transition remains unresolved. To that end, this paper explores the economic, environmental, and social challenges presented by the energy transition at the community level, highlighting four case studies from transitioning coal-dependent communities across the United States to ultimately identify best practices in coal plant decommissioning processes. This paper weaves these community-identified best practices into two support tools—a decommissioning checklist and a redevelopment decision-making framework—that can be used to engage communities in the power plant retirement decision, the site reclamation phase, and eventual redevelopment of the site and revitalization of the surrounding community.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Chapter 6: TEA and LCA of Bio-Based Polyurethanes

For bio-based polyurethane (PU) to replace its conventional petroleum-based counterpart, it must be cost-competitive while providing a positive environmental benefit. Techno-economic analysis (TEA) and life cycle assessment (LCA) provide tools to quantify the economic and environmental viability of bio-based PU and to identify key drivers. Here we describe TEA and LCA methodologies for assessing bio-based PU, including an example case study for producing a flexible PU foam. This process has the potential to be cost-competitive with traditional PU based on a published study using a linseed oil proxy feedstock. Bio-based PU also demonstrates environmental advantages in some categories considered but faces challenges in others compared to petroleum-based PU. Further TEA and LCA beyond the case study may enable assessment for alternative product and process variations that are possible for bio-based PU.

bio-based polyurethane↗

The mechanisms of ductile rupture

One of the most confounding controversies in the ductile fracture community is the large discrepancy between predicted and experimentally observed strain-to-failure values during shear-dominant loading. Currently presented solutions focus on better accounting for how the deviatoric stress state influences void growth or on measuring strain at the microscale rather than the macroscale. While these approaches are useful, they do not address a significant aspect of the problem: the only rupture micromechanisms that are generally considered are void nucleation, growth, and coalescence (for tensile-dominated loading), and shear-localization and void coalescence (for shear-dominated loading). Current phenomenological models have thus focused on predicting the competition between these mechanisms based on the stress state and the strain-hardening capacity of the material. However, in the present study, we demonstrate that there are at least five other failure mechanisms. Because these have long been ignored, little is known about how all seven mechanisms interact with one another or the factors that control their competition. These questions are addressed by characterizing the fracture process in three high-purity face-centered cubic (FCC) metals of medium-to-high stacking fault energy: copper, nickel, and aluminum. These data demonstrate that, for a given stress state and material, several mechanisms frequently work together in a sequential manner to cause fracture. The selection of a failure mechanism is significantly affected by the plasticity-induced microstructural evolution that occurs before tearing begins, which can create or eliminate sites for void nucleation. At the macroscale, failure mechanisms that do not involve cracking or pore growth were observed to facilitate subsequent void growth and coalescence processes. Even though the focus of this study is on damage accumulation in pure metals, these results are also applicable to understanding failure in engineering alloys.

36 MATERIALS SCIENCE↗

Nuclear properties for astrophysical and radioactive-ion-beam applications (II)

We tabulate the ground-state odd-proton and odd-neutron spins and parities, proton and neutron pairing gaps, one- and two-neutron separation energies, quantities related to β-delayed one- and two-neutron emission probabilities, average energy and average number of emitted neutrons, β-decay energy release and half-life with respect to Gamow–Teller decay with a phenomenological treatment of first-forbidden decays, one- and two-proton separation energies, and α-decay energy release and half-life for 9318 nuclei ranging from {sup 16}O to {sup 339}136 and extending from the proton drip line to the neutron drip line. This paper is a new and improved version of Atomic Data And Nuclear Data Tables [66 131 (1997)]. The starting point of our present work is the new study (FRDM(2012)) of nuclear ground-state masses and deformations based on the finite-range droplet model and folded-Yukawa single-particle potential published in a previous issue of Atomic Data And Nuclear Data Tables [109–110, 1 (2016)]. The β-delayed neutron-emission probabilities and Gamow–Teller β-decay rates are obtained from a quasi-particle random-phase approximation with single-particle levels and wave functions at the calculated nuclear ground-state shapes as input quantities. A development since 1997 is we now use a Hauser–Feshbach approach to account for (n, γ) competition and treat first-forbidden decay in a phenomenological approach.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Assessment of Algal Farm Designs Using a Dynamic Modular Approach

The notion of renewable energy provides an important mechanism for diversifying an energy portfolio, which ultimately would have numerous benefits including increased energy resilience, reduction of foreign energy supplies, reduced GHG emissions, development of a green energy sector that contributes to economic growth, and providing a sustainable energy supply. The conversion of autotrophic algae to liquid transportation fuels is the basis of several decades of research to competitively bring energy-scale production into reality; however, many challenges still remain for making algal biofuels economically viable. Addressing current challenges associated with algal production systems, in part, requires the ability to assess spatial and temporal variability, rapidly evaluate alternative algal production system designs, and perform large-scale assessments considering multiple scenarios for thousands of potential sites. We introduce the Algae Logistics Model (ALM) which helps to address these challenges. The flexible nature of the ALM architecture allows the model to: 1) interface with external biomass production and resource assessment models, as well as other relevant datasets including those with spatiotemporal granularity; 2) interchange design processes to enable operational and economic assessments of multiple design configurations, including the integration of current and new innovative technologies; and 3) conduct trade-off analysis to help understand the site-specific techno-economic trade-offs and inform technology decisions. This study uses the ALM to investigate a baseline open-pond production system determined by model harmonization efforts conducted by the U.S. Department of Energy. Six sites in the U.S. southern-tier were sub-selected and assessed using daily site-specific algae biomass productivity data to determine the economic viability of large-scale open-pond systems. Results show that costs can vary significantly depending on location and biomass productivity and that integration of novel dewatering equipment, order of operations, and equipment scaling can also have significant impacts on economics.

09 BIOMASS FUELS↗

An integrated assessment of location-dependent scaling for microalgae biofuel production facilities

Successful development of a large-scale microalgae-based biofuels industry requires comprehensive analysis and understanding of the feedstock supply chain—from facility siting and design through processing and upgrading of the feedstock to a fuel product. The evolution from pilot-scale production facilities to energy-scale operations presents many multi-disciplinary challenges, including a sustainable supply of water and nutrients, operational and infrastructure logistics, and economic competitiveness with petroleum-based fuels. These challenges are partially addressed by applying the Integrated Assessment Framework (IAF) – an integrated multi-scale modeling, analysis, and data management suite – to address key issues in developing and operating an open-pond microalgae production facility. This is done by analyzing how variability and uncertainty over space and through time affect feedstock production rates, and determining the site-specific “optimum” facility scale to minimize capital and operational expenses. This approach explicitly and systematically assesses the interdependence of biofuel production potential, associated resource requirements, and production system design trade-offs. To provide a baseline analysis, the IAF was applied in this paper to a set of sites in the southeastern U.S. with the potential to cumulatively produce 5 billion gallons per year. Finally, the results indicate costs can be reduced by scaling downstream processing capabilities to fit site-specific growing conditions, available and economically viable resources, and specific microalgal strains.

09 BIOMASS FUELS↗