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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Effects of soiling and weathering on the albedo of building envelope materials: Lessons learned from natural exposure in two European cities and tuning of a laboratory simulation practice

Chemical and physical stress, weathering, organic and inorganic matter deposition, and microbial growth over time, or “aging”, affect the optical-radiative performance of building envelope materials. Natural exposure helps to quantify these effects, but it usually requires several years. Further, the contribution of the different degradation agents cannot be isolated, and results from different campaigns cannot be easily compared because of the variability in the boundary conditions producing aging. Here in this paper we present an adaptation of the protocol implemented by ASTM as D7897-18 “Standard Practice for Laboratory Soiling and Weathering of Roofing Materials to Simulate Effects of Natural Exposure on Solar Reflectance and Thermal Emittance”. The aim is to reproduce in the laboratory the changes in albedo (solar reflectance) and thermal emittance experienced by building envelope materials in European urban areas rather than in the United States. We tuned the spraying duration and weathering cycles, and we compared the UV–vis–NIR reflectances of naturally-aged specimens (48 months in Rome and Milan) of roofing and wall finish materials to those exposed to laboratory weathering and soiling. Excluding those materials that show early physical-chemical degradation, the mean absolute deviation between natural and laboratory exposure of roofing products is equal to 0.027 in albedo. This is a lower value than the differences between two natural exposure campaigns at the same site. We clearly defined the limits of application of the protocol, providing an appraisal of the repeatability of natural aging. Moreover, we identified possible improvements in the methodology to conduct both natural and laboratory exposure.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Riders’ perceptions towards transit bus electrification: Evidence from Salt Lake City, Utah

While battery electric buses (BEBs) can lead to energy savings and reduced emissions, BEB adoption is developing slowly. Although BEBs offer quieter operations, better acceleration, and no smell of diesel or gas fumes, little focus has been placed on the user’s perspective. Here, this study investigates bus riders’ preferences toward BEBs. To achieve these objectives, a survey was designed and administered to solicit riders’ typical travel behaviors and patterns as well as preferences and opinions about BEBs’ performance in terms of emissions and noise. Statistical analysis showed that several factors influence rider perceptions towards transit bus electrification that include trip purpose, attitudes towards environmental issues and environmental impacts of BEBs, and certain non-instrumental ride factors such as ride comfort and social image. A better understanding of the importance of electrification to transit riders can help transit service providers adjust their marketing decisions and their systemwide operations to accommodate preferences towards BEBs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Converting the organic fraction of solid waste from the city of Abu Dhabi to valuable products via dark fermentation – Economic and energy assessment

Graphical abstract: Display Omitted - Highlights: • The cost and energy demand for dark fermentation using OFMSW were established. • Dark fermentation using OFMSW can produce a carbon source for bioprocesses of about 330 USD/t{sub COD}. • A maximum purification cost of VFAs from dark fermentation using OFMSW was established to 15 USD/m{sup 3}. • Replacing fossil fuel based products by dark fermentation will probably lead to net energy savings. - Abstract: Landfilling the organic fraction of municipal solid waste (OFMSW) leads to greenhouse gas emissions and loss of valuable resources. Sustainable and cost efficient solutions need to be developed to solve this problem. This study evaluates the feasibility of using dark fermentation (DF) to convert the OFMSW to volatile fatty acids (VFAs), fertilizer and H{sub 2}. The VFAs in the DF effluent can be used directly as substrate for subsequent bioprocesses or purified from the effluent for industrial use. DF of the OFMSW in Abu Dhabi will be economically sustainable once VFA purification can be accomplished on large scale for less than 15 USD/m{sup 3}{sub effluent}. With a VFA minimum selling price of 330 USD/t{sub COD}, DF provides a competitive carbon source to sugar. Furthermore, DF is likely to use less energy than conventional processes that produce VFAs, fertilizer and H{sub 2}. This makes DF of OFMSW a promising waste treatment technology and biorefinery platform.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Estimating Carbon Dioxide Emissions in Two California Cities Using Bayesian Inversion and Satellite Measurements

NASA's Orbiting Carbon Observatories (OCO-2 and OCO-3) provide measurements of column-averaged carbon dioxide concentrations (XCO 2 ) with sufficient spatial resolution and precision to constrain bottom-up estimates of CO 2 fluxes at regional scales. We use Bayesian inversion methods assimilating satellite retrievals to improve estimates of CO 2 fluxes in the South Coast Air Basin (SoCAB) which surrounds Los Angeles, and in the San Francisco Bay Area Air Basin (SFBA). We study 2020 to understand the impact of the COVID-19 lockdowns and an active wildfire season. Our results indicated that a 50% (30%) reduction in CO 2 emissions relative to 2015 during the COVID-19 lockdown period was consistent with OCO measurements for SFBA (SoCAB). We find that posterior wildfire emissions differed significantly from the prior at the scale of individual wildfires, though with large uncertainties, and that wildfire emissions in SFBA are significant, attributing 72% of the region's CO 2 emissions during August 2020 to wildfires.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Quantifying Movement Motivations, Demand, and Inflow-Outflow Dynamics in Four Cities (New York, Chicago, Austin, and San Diego) During COVID-19

The COVID-19 pandemic has impacted a wide range of human activities, from food delivery habits to major moving and travel decisions. Results indicate multiple pandemic-related factors have influenced millions of relocation decisions by Americans (e.g., health risk, financial pressures, more space, and employment), and there are various positive economic and social outcomes of this influence (e.g., remote work and education), enabling more affordable living and opportunity. This paper addresses COVID-19 impacts on mobility, especially involving permanent relocations. Survey design and data analysis with U-Haul targeted customers in Austin, New York, San Diego, and Chicago to understand mobility, new moving dynamics, and motivations.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
DOE OSTI2015

Estimation of missing values in solar radiation data using piecewise interpolation methods: Case study at Penang city

The solar radiation values have been composed by automatic weather station using the device that namely pyranometer. The device is functions to records all the radiation values that have been dispersed, and these data are very useful for it experimental works and solar device’s development. In addition, for modeling and designing on solar radiation system application is needed for complete data observation. Unfortunately, lack for obtained the complete solar radiation data frequently occur due to several technical problems, which mainly contributed by monitoring device. Into encountering this matter, estimation missing values in an effort to substitute absent values with imputed data. This paper aimed to evaluate several piecewise interpolation techniques likes linear, splines, cubic, and nearest neighbor into dealing missing values in hourly solar radiation data. Then, proposed an extendable work into investigating the potential used of cubic Bezier technique and cubic Said-ball method as estimator tools. As result, methods for cubic Bezier and Said-ball perform the best compare to another piecewise imputation technique.

14 SOLAR ENERGY↗
DOE OSTI2015

Rubble masonry response under cyclic actions: The experience of L’Aquila city (Italy)

Several methods of analysis are available in engineering practice to study old masonry constructions. Two commonly used approaches in the field of seismic engineering are global and local analyses. Despite several years of research in this field, the various methodologies suffer from a lack of comprehensive experimental validation. This is mainly due to the difficulty in simulating the many different kinds of masonry and, accordingly, the non-linear response under horizontal actions. This issue can be addressed by examining the local response of isolated panels under monotonic and/or alternate actions. Different testing methodologies are commonly used to identify the local response of old masonry. These range from simplified pull-out tests to sophisticated in-plane monotonic tests. However, there is a lack of both knowledge and critical comparison between experimental validations and numerical simulations. This is mainly due to the difficulties in implementing irregular settings within both simplified and advanced numerical analyses. Similarly, the simulation of degradation effects within laboratory tests is difficult with respect to old masonry in-situ boundary conditions. Numerical models, particularly on rubble masonry, are commonly simplified. They are mainly based on a kinematic chain of rigid blocks able to perform different “modes of damage” of structures subjected to horizontal actions. This paper presents an innovative methodology for testing; its aim is to identify a simplified model for out-of-plane response of rubbleworks with respect to the experimental evidence. The case study of L’Aquila district is discussed.

58 GEOSCIENCES↗
DOE OSTI2013

Ancient light from young cosmic cities: Physical and observational signatures of galaxy proto-clusters

A growing number of galaxy clusters at z = 1-2 is being discovered as part of deep optical, IR, X-ray, and Sunyaev-Zel'dovich effect surveys. For a complete picture of cluster formation, however, it is important that we also start probing the much earlier epoch, between redshifts of about 2 and 7, during which these clusters and their galaxies first began to form. Because the study of these so-called proto-clusters is currently quite limited by small number statistics, widely varying selection techniques, and many assumptions, we have performed a large systematic study of cluster formation utilizing cosmological simulations. We use the Millennium Simulations to track the evolution of dark matter and galaxies in about 3000 clusters from the earliest times to z = 0. We define an effective radius R{sub e} for proto-clusters and characterize their growth in size and mass with cosmic time. We show that the progenitor regions of galaxy clusters (ranging in mass from ∼10{sup 14} to a few times 10{sup 15} M {sub ☉}) can already be identified in galaxy surveys at very early times (at least up to z ∼ 5), provided that the galaxy overdensities are measured on a sufficiently large scale (R{sub e} ∼ 5-10 Mpc comoving) and with sufficient statistics. We present the overdensities in matter, dark matter halos, and galaxies as functions of present-day cluster mass, redshift, bias, and window size that can be used to interpret the wide range of structures found in real surveys. We also derive the probability that a structure having a galaxy overdensity δ{sub gal}, defined by a set of observational selection criteria, is indeed a proto-cluster, and we show how their z = 0 masses can already be estimated long before virialization. We present overdensity profiles as a function of radius, and we further show how the projected surface overdensities of proto-clusters decrease as the uncertainties in redshift measurements increase. We provide a table of proto-cluster candidates selected from the literature and discuss their properties in light of our simulation predictions. This paper provides the general framework that will allow us to extend the study of cluster formation out to much higher redshifts using the large number of proto-clusters that are expected to be discovered in, e.g., the upcoming HETDEX and Hyper Suprime-Cam surveys.

79 ASTRONOMY AND ASTROPHYSICS↗