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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Three-Phase Modular Cascaded H-Bridge Multilevel Inverter with Individual MPPT for Grid-Connected Photovoltaic Systems

A three-phase modular cascaded H-bridge multilevel inverter for a grid-connected photovoltaic (PV) system is presented in this paper. To maximize the solar energy extraction of each PV string, an individual maximum power point tracking (MPPT) control scheme is applied, which allows the independent control of each dc-link voltage. PV mismatches may introduce unbalanced power supplied to the three-phase system. To solve this issue, a control scheme with modulation compensation is proposed. The three-phase modular cascaded multilevel inverter prototype has been built. Each H-bridge is connected to a 185 W solar panel. Simulation and experimental results are presented to validate the proposed ideas.

14 SOLAR ENERGY↗
DOE OSTI2014

Existing Whole-House Solutions Case Study: Cascade Apartments - Deep Energy Multifamily Retrofit

In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington, which resulted in annual energy cost savings of 22%, improved comfort and air quality for residents, and increased durability of the units. This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary Building America research questions: 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio of the retrofit package after considering utility window incentives and KCHA capital improvement funding.

BA-PIRC↗
DOE OSTI2015

Numerical Investigation of a Cascaded Longitudinal Space-Charge Amplifier at the Fermilab's Advanced Superconducting Test Accelerator

In a cascaded longitudinal space-charge amplifier (LSCA), initial density noise in a relativistic e-beam is amplified via the interplay of longitudinal space charge forces and properly located dispersive sections. This type of amplification process was shown to potentially result in large final density modulations [1] compatible with the production of broadband electromagnetic radiation. The technique was recently demonstrated in the optical domain [2]. In this paper we investigate, via numerical simulations, the performances of a cascaded LSCA beamline at the Fermilab’s Advanced Superconducting Test Accelerator (ASTA). We especially explore the properties of the produced broadband radiation. Our studies have been conducted with a grid-less three-dimensional space-charge algorithm.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Cascaded systems and methods for controlling energy use during a demand limiting period

A cascaded control system is configured to control power consumption of a building during a demand limiting period. The cascaded control system includes an energy use setpoint generator and a feedback controller. The energy use setpoint generator is configured to use energy pricing data and measurements of a variable condition within the building to generate an energy use setpoint during the demand limiting period. The feedback controller is configured to use a difference between the energy use setpoint and a measured energy use to generate a control signal for building equipment that operate to affect the variable condition within the building during the demand limiting period.

Wenzel, Michael J.↗
DOE OSTI2021

Exciton management in organic photovoltaic multi-donor energy cascades

Disclosed herein are organic photosensitive optoelectronic devices, such as organic photovoltaics, including a photoactive region, wherein the photoactive region contains an energy-cascading multilayer donor region. The energy-cascading multilayer donor region may drive exciton transfer from an anode to a dissociating interface while reducing exciton quenching, improving overlap with the solar spectrum, and minimizing polaron pair recombination, resulting in improved device performance.

Forrest, Stephen R.↗
DOE OSTI2021

Cascaded systems and methods for controlling energy use during a demand limiting period

A cascaded control system is configured to control power consumption of a building during a demand limiting period. The cascaded control system includes an energy use setpoint generator and a feedback controller. The energy use setpoint generator is configured to use energy pricing data and measurements of a variable condition within the building to generate an energy use setpoint during the demand limiting period. The feedback controller is configured to use a difference between the energy use setpoint and a measured energy use to generate a control signal for building equipment that operate to affect the variable condition within the building during the demand limiting period.

Wenzel, Michael J.↗
DOE OSTI2011

Erlotinib inhibits T-cell-mediated immune response via down-regulation of the c-Raf/ERK cascade and Akt signaling pathway

Erlotinib is a potent inhibitor of epidermal growth factor receptor tyrosine kinase and has been demonstrated to treat advanced or metastatic non-small cell lung cancer to prolong survival after failure of first-line or second-line chemotherapy. However, little is known about its effects on immune system. In the present study, we aimed to investigate the immunosuppressive activity of erlotinib on T lymphocytes both in vitro and in vivo, and further explore its potential molecular mechanism. Erlotinib exerted a significant inhibition on the T cell proliferation and activation induced by concanavalin A, anti-CD3 plus anti-CD28, staphylococcal enterotoxin B or phorbol myristate acetate respectively in a concentration-dependent manner and it also inhibited the secretion of the proinflammatory cytokines such as IL-2 and IFN-{gamma} of activated T cells. Further study showed that erlotinib caused G0/G1 arrest and suppressed the phosphorylations of c-Raf, ERK and Akt in activated T cells. Moreover, erlotinib significantly ameliorated picryl chloride-induced ear contact dermatitis in a dose-dependent manner in vivo. In summary, these findings suggest that erlotinib may cause the impairment of T-cell-mediated immune response both in vitro and in vivo through inhibiting T cell proliferation and activation, which is closely associated with its potent down-regulation of the c-Raf/ERK cascade and Akt signaling pathway. - Graphical abstract: Erlotinib may cause the impairment of T-cell-mediated immune response both in vitro and in vivo through inhibiting T cell proliferation and activation, which is closely associated with its potent down-regulation of the c-Raf/ERK cascade and Akt signaling pathway. Display Omitted

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

First and second order approximations to stage numbers in multicomponent enrichment cascades

This paper describes closed form, Taylor series approximations to the number product stages in a multicomponent enrichment cascade. Such closed form approximations are required when a symbolic, rather than a numeric, algorithm is used to compute the optimal cascade state. Both first and second order approximations were implemented. The first order solution was found to be grossly incorrect, having the wrong functional form over the entire domain. On the other hand, the second order solution shows excellent agreement with the 'true' solution over the domain of interest. An implementation of the symbolic, second order solver is available in the free and open source PyNE library. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Development and Testing of an Advanced Cascaded Thermoelectric Residential Heat Pump

Electricity-driven heat pumps using vapor compression cycle are an energy-efficient solution to replace fossil fuel burning and reduce greenhouse gas emissions for space heating in residential buildings. However, heating capacity and Coefficient of Performance (COP) of heat pumps degrade significantly with increasing temperature difference between ambient and indoor environments. Residents and building owners are hence reluctant to fully embrace electric heat pumps. The use of conventional all-electric heat pumps also causes concern for electric utilities due to an increased winter peak demand arising from the use of supplemental electric resistance heaters. Our research is an attempt to alleviate these concerns by designing and laboratory testing a thermoelectric (TE) heat pump cascaded with a vapor compression cycle to enhance heating capacity and COP. TE modules increase the subcooling in the refrigerant liquid of the vapor compression cycle to enlarge the evaporating capacity and works at an efficiency greater than a conventional electric resistance strip. This results in a simple, affordable, efficient and highly controllable solution to adequately meet space heating needs in dwellings. The laboratory testing of the 3-stage cascaded TE heat pump performed in this research has exhibited a higher heating capacity by above 15%, while maintaining a heating COP of 2.0-3.6 in the ambient temperature range of -18˚C to 8˚C (0˚F to 47 ˚F), which represents more than 60% of winter temperatures observed in US. If successfully commercialized, this technology can advance space-heating electrification by overcoming consumer cost barrier of heat pumps.

Shen, Bo↗
DOE OSTI2015

Frequency locking and monitoring based on Bi-directional terahertz radiation of a 3 rd -order distributed feedback quantum cascade laser

In this study, we have performed frequency locking of a dual, forward reverse emitting third-order distributed feedback quantum cascade laser (QCL) at 3.5 THz. By using both directions of THz emission in combination with two gas cells and two power detectors, we can for the first time perform frequency stabilization, while monitor the frequency locking quality independently. We also characterize how the use of a less sensitive pyroelectric detector can influence the quality of frequency locking, illustrating experimentally that the sensitivity of the detectors is crucial. Using both directions of terahertz (THz) radiation has a particular advantage for the application of a QCL as a local oscillator, where radiation from one side can be used for frequency/phase stabilization, leaving the other side to be fully utilized as a local oscillator to pump a mixer.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Distributed feedback interband cascade lasers with top grating and corrugated sidewalls

Distributed feedback (DFB) interband cascade lasers (ICL) with a 1st order top surface grating were designed and fabricated. Partially-corrugated sidewalls were implemented to suppress high order lateral modes. The DFB ICLs have 4 mm long and 4.5 μm wide ridge waveguides, and are mounted epi-up on AlN submounts. We demonstrated a continuous-wave (CW) DFB ICL, from a first wafer which has a large detuning of gain peak from the DFB wavelength, with a side mode suppression ratio of 30 dB. With proper matching of grating feedback and gain peak wavelength for the second wafer, a DFB ICL was demonstrated with a maximum CW output power and maximum wall plug efficiency reaching 42 mW and 2 %, respectively, at 25°C. The lasing wavelengths of both lasers are around 3.3 μm at 25°C.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Two-step narrow ridge cascade diode lasers emitting near $2~\mu$ m

Nearly diffraction limited GaSb-based type-I quantum well cascade diode lasers emitting in the spectral region 1.95-2 μm were designed and fabricated. Two-step 5.5-μm-wide shallow and 14-μm-wide deep etched ridge waveguide design yielded devices generating stable single lobe beams with 250 mW of continuous wave output power at 20 °C. Quantum well radiative recombination current contributes about 13% to laser threshold as estimated from true spontaneous emission and modal gain analysis. Here, recombination at etched sidewalls of the 14-μmwide deep ridges controls about 30% of the threshold.

42 ENGINEERING↗
DOE OSTI2015

Oregon Cascades Play Fairway Analysis: Raster Datasets and Models

This submission includes maps of the spatial distribution of basaltic, and felsic rocks in the Oregon Cascades. It also includes a final Play Fairway Analysis (PFA) model, with the heat and permeability composite risk segments (CRS) supplied separately. Metadata for each raster dataset can be found within the zip files, in the TIF images

15 GEOTHERMAL ENERGY↗
NASA NTRS1951

Secondary flows in annular cascades and effects on flow in inlet guide vanes

Qualitative discussion is presented of the general nature of secondary flows in stationary annular cascades with thin wall boundary layers and radial design variation of circulation. Deviations from ideal mean outlet flows (based on blade-element performance) exist in potential-flow region of vanes because of conditions imposed by end-wall boundaries, displacement of wall boundary layers toward blade suction surfaces, and irrotationality requirement. As a consequence of existence of nonuniform radial flow across blade spacing, it may not generally be possible to obtain an arbitrarily specified design variation of the turning angle along the radial height of a blade row. Quantitative turning angle corrections due to effects of secondary flows in axial-flow compressor inlet guide vanes were obtained from induced deflections of a superimposed vortex system in conjunction with an empirically determined correlation factor.

CASCADES, EXPERIMENT↗
DOE OSTI2023

Reconfigurable Cascaded Thermal Neuristors for Neuromorphic Computing

While the complementary metal-oxide semiconductor (CMOS) technology is the mainstream for the hardware implementation of neural networks, an alternative route is explored based on a new class of spiking oscillators called “thermal neuristors”, which operate and interact solely via thermal processes. Utilizing the insulator-to-metal transition (IMT) in vanadium dioxide, a wide variety of reconfigurable electrical dynamics mirroring biological neurons is demonstrated. Notably, inhibitory functionality is achieved just in a single oxide device, and cascaded information flow is realized exclusively through thermal interactions. To elucidate the underlying mechanisms of the neuristors, a detailed theoretical model is developed, which accurately reflects the experimental results. In conclusion, this study establishes the foundation for scalable and energy-efficient thermal neural networks, fostering progress in brain-inspired computing.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Nonorthogonal Cascade Catalysis in Multicompartment Micelles

Multicompartment micelles (MCMs) containing acid and base sites in discrete domains are prepared from poly(norbornene)-based amphiphilic bottlebrush copolymers in aqueous media. Here, the acid and base sites are localized in different compartments of the micelle, enabling the nonorthogonal reaction sequence: deacetalization – Knoevenagel condensation – Michael addition of acetals to 2-amino chromene derivatives. Computational simulations using dissipative particle dynamics (DPD) elucidated the bottlebrush composition required to effectively site-isolate the nonorthogonal catalysts. This contribution presents MCMs as a new class of nanostructures for one-pot multistep nonorthogonal cascade catalysis, laying the groundwork for the isolation of three or more incompatible catalysts to synthesize value-added compounds in a single reaction vessel, in water.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗