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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 325 records · Page 18

Integration, Validation, and Application of a PV Snow Coverage Model in SAM

Due to the increasing deployment of PV systems in snowy climates, there is significant interest in a method capable of estimating PV losses resulting from snow coverage that has been verified for a wide variety of system designs and locations. A scattering of independent snow coverage models have been developed over the last 15 years; however, there has been very little effort spent on verifying these models beyond the system design and location on which they were based. Moreover, none of the major PV modeling software products have incorporated any of these models into their workflow. In response to this deficiency, we have integrated the methodology of the snow model developed in the paper by Marion et al. [1] into the National Renewable Energy Laboratory's (NREL) System Advisor Model (SAM). In this work we describe how the snow model is implemented in SAM and discuss our demonstration of the model's effectiveness at reducing error in annual estimations for two PV arrays. Following this, we use this new functionality in conjunction with a long term historical dataset to estimate average snow losses across the United States for a typical PV system design. The open availability of the snow loss estimation capability in SAM to the PV modeling community, coupled with our results of the nation-wide study, will better equip the industry to accurately estimate PV energy production in areas affected by snowfall.

14 SOLAR ENERGY↗

Particle integrity, sampling, and application of a DNA-tagged tracer for aerosol transport studies

Aerosols are an ever-present part of our daily environment and have extensive effects on both human and environmental health. Particles in the inhalable range (1-10 μm diameter) are of particular concern because their deposition in the lung can lead to a variety of illnesses including allergic reactions, viral or bacterial infections, and cancer. Understanding the transport of inhalable aerosols across both short and long distances is necessary to predict human exposures to aerosols. To assess the transport of hazardous aerosols, surrogate tracer particles are required to measure their transport through occupied spaces. These tracer particles must not only possess similar transport characteristics to those of interest but also be easily distinguished from the background at low levels and survive the environmental conditions of the testing environment. A previously-developed DNA-tagged particle (DNATrax), composed of food-grade sugar and a DNA oligonucleotide as a “barcode” label, shows promise as a new aerosol tracer. Herein, the use of DNATrax material is validated for use in both indoor and outdoor environments. Utilizing passive samplers made of materials commonly found in indoor environments followed by quantitative polymerase chain reaction (qPCR) assay for endpoint particle detection, particles detection was achieved up to 90 m from the aerosolization location and across shorter distances with high spatial resolution. The unique DNA label and PCR assay specificity were leveraged to perform multiple simultaneous experiments. This allowed the assessment of experimental reproducibility, a rare occurrence among aerosol field tests. To transition to outdoor testing, the solid material provides some protection of the DNA label when exposed to ultraviolet (UV) radiation, with 60% of the DNA remaining intact after 60 minutes under a germicidal lamp and the rate of degradation declining with irradiation time. Additionally, exposure of the DNATrax material using formulations of two different food-grade sugars (maltodextrin and erythritol) to humidity as high as 66% had no significant effect on the DNA label’s degradation or the particle’s aerodynamic diameter, confirming particle stability under such conditions. In summary, confirmation of the DNATrax particles’ size and label integrity under variable conditions combined with experiment multiplexing and high resolution sampling provides a powerful experimental design for modeling aerosol transport through occupied indoor and outdoor locations.

54 ENVIRONMENTAL SCIENCES↗

On DESTINY Science Instrument Electrical and Electronics Subsystem Framework

Future space missions are going to require large focal planes with many sensing arrays and hundreds of millions of pixels all read out at high data rates'' . This will place unique demands on the electrical and electronics (EE) subsystem design and it will be critically important to have high technology readiness level (TRL) EE concepts ready to support such missions. One such omission is the Joint Dark Energy Mission (JDEM) charged with making precise measurements of the expansion rate of the universe to reveal vital clues about the nature of dark energy - a hypothetical form of energy that permeates all of space and tends to increase the rate of the expansion. One of three JDEM concept studies - the Dark Energy Space Telescope (DESTINY) was conducted in 2008 at the NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. This paper presents the EE subsystem framework, which evolved from the DESTINY science instrument study. It describes the main challenges and implementation concepts related to the design of an EE subsystem featuring multiple focal planes populated with dozens of large arrays and millions of pixels. The focal planes are passively cooled to cryogenic temperatures (below 140 K). The sensor mosaic is controlled by a large number of Readout Integrated Circuits and Application Specific Integrated Circuits - the ROICs/ASICs in near proximity to their sensor focal planes. The ASICs, in turn, are serviced by a set of "warm" EE subsystem boxes performing Field Programmable Gate Array (FPGA) based digital signal processing (DSP) computations of complex algorithms, such as sampling-up-the-ramp algorithm (SUTR), over large volumes of fast data streams. The SUTR boxes are supported by the Instrument Control/Command and Data Handling box (ICDH Primary and Backup boxes) for lossless data compression, command and low volume telemetry handling, power conversion and for communications with the spacecraft. The paper outlines how the JDEM DESTINY concept instrument EE subsystem can be built now, a design; which is generally U.S. Government work not protected by U.S. copyright IEEEAC paper # 1429. Version 4. Updated October 19, 2009 applicable to a wide variety of missions using large focal planes with lar ge mosaics of sensors.

Kizhner, Semion↗

Examining CCS deployment potential in China via application of an integrated CCS cost curve

Cost curves focusing on CO2 transport and storage have been previously published and used to help establish the large potential for CCS technologies to deploy in China. This paper examines the results from recent work to incorporate the costs of CO2 capture and compression within integrated cost curves that better reflect the complete costs and therefore possible value of CCS. Results show that significant potential exists for large-scale deployment of CCS at costs less than $70/tCO2. Mapping of the cost curve results confirms that the majority of existing CO2 point sources may be able to utilize CCS technologies, and that - except for many sources in southern China - onshore storage capacity appears accessible and sufficient for decades of large-scale deployment.

Carbon dioxide capture and storage↗

A Review of the Multiple-Readout Concept and Its Application in an Integrally Active Calorimeter

A comprehensive multi-jet physics program is anticipated for experiments at future colliders. Key physics processes necessitate detectors that can distinguish signals from W and Z bosons and the Higgs boson. Typical examples include channels with or pairs and processes involving new physics in those cases where neutral particles must be disentangled from charged ones due to the presence of W or Z bosons in their final states. Such a physics program demands calorimetric energy resolution at or beyond the limits of traditional calorimetric techniques. Multiple-readout calorimetry, which aims to reduce fluctuations in energy measurements of hadronic showers, is a promising approach. The first part of this article reviews dual- and triple-readout calorimetry within a mathematical framework describing the underlying compensating mechanism. The second part proposes a potential implementation using an integrally active and total absorption detector. This model serves as the basis for several Monte Carlo studies, illustrating how the response of a multiple-readout calorimeter depends on construction parameters. Among the layouts considered, one configuration operating in triple-readout mode shows the potential to achieve an energy resolution approaching .

47 OTHER INSTRUMENTATION↗

Numerical integration and Riemann-Stieltjes sums.

Numerical integration based on definition of Riemann integral, describing application to nonlinear integral equations of isotropic scattering of radiation in plane parallel atmosphere

RIEMANN INTEGRAL↗

Application of boundary integral method to elastic analysis of V-notched beams

A semidirect boundary integral method, using Airy's stress function and its derivatives in Green's boundary integral formula, is used to obtain an accurate numerical solution for elastic stress and strain fields in V-notched beams in pure bending. The proper choice of nodal spacing on the boundary is shown to be necessary to achieve an accurate stress field in the vicinity of the tip of the notch. Excellent agreement is obtained with the results of the collocation method of solution.

Rzasnicki, W.↗