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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Heat Exchangers Circuitry Optimization using Low-GWP Refrigerants in Reversible Heat Pump Applications

Tube-fin heat exchangers (TFHX) are widely used in heat pump applications. Circuitry optimization can improve system performance. Previous optimizations focus on improving component-level performance under a specific operating condition, i.e., the TFHX either works as a condenser or an evaporator. The optimal circuitry obtained under air conditioning (AC) mode cannot guarantee optimal performance when used in heat pump (HP) mode. This study implements a bi-objective formulation to achieve optimal system performance in both AC and HP modes. An integer permutation-based Genetic Algorithm is integrated with Heat Pump Design Model (HPDM) to perform heat pump optimization. Six refrigerants, i.e., R410A, R452B, R454B, R32, D2Y60 and L41a are investigated. Case studies show that optimal heat exchangers yield 2.1%-6.1% EER improvement under AC mode and 1.9%-8.5% COP improvement under HP mode. Use of this design approach can help assure a preferable performance of reversible heat pumps during both cooling and heating mode usage.

Li, Zhenning↗
DOE OSTI2022

Molecular dissection of the glutamine synthetase-GlnR nitrogen regulatory circuitry in Gram-positive bacteria

How bacteria sense and respond to nitrogen levels are central questions in microbial physiology. In Gram-positive bacteria, nitrogen homeostasis is controlled by an operon encoding glutamine synthetase (GS), a dodecameric machine that assimilates ammonium into glutamine, and the GlnR repressor. GlnR detects nitrogen excess indirectly by binding glutamine-feedback-inhibited-GS (FBI-GS), which activates its transcription-repression function. The molecular mechanisms behind this regulatory circuitry, however, are unknown. Here we describe biochemical and structural analyses of GS and FBI-GS-GlnR complexes from pathogenic and non-pathogenic Gram-positive bacteria. The structures show FBI-GS binds the GlnR C-terminal domain within its active-site cavity, juxtaposing two GlnR monomers to form a DNA-binding-competent GlnR dimer. The FBI-GS-GlnR interaction stabilizes the inactive GS conformation. Strikingly, this interaction also favors a remarkable dodecamer to tetradecamer transition in some GS, breaking the paradigm that all bacterial GS are dodecamers. These data thus unveil unique structural mechanisms of transcription and enzymatic regulation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Magnonic beam splitter: The building block of parallel magnonic circuitry

We demonstrate a magnonic beam splitter that works by inter-converting magnetostatic surface and backward-volume spin waves propagating in orthogonal sections of a T-shaped yttrium iron garnet structure. The inter-conversion is enabled by the overlap of the surface and volume spin wave bands. This overlap results from the demagnetising field induced along the transversely magnetised section(-s) of the structure and the quantization of the transverse wave number of the propagating spin waves (which are therefore better described as waveguide modes). In agreement with numerical micromagnetic simulations, our Brillouin light scattering imaging experiments reveal that, depending on the frequency, the incident fundamental waveguide magnonic modes may also be converted into higher order waveguide modes. The magnonic beam splitter demonstrated here is an important step towards the development of parallel logic circuitry of magnonics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Dissection of the molecular circuitry controlling virulence in Francisella tularensis

Francisella tularensis , the etiological agent of tularemia, is one of the most infectious bacteria known. Because of its extreme pathogenicity, F. tularensis is classified as a category A bioweapon by the US government. F. tularensis virulence stems from genes encoded on the Francisella pathogenicity island (FPI). An unusual set of Francisella regulators—the heteromeric macrophage growth locus protein A (MglA)–stringent starvation protein A (SspA) complex and the DNA-binding protein pathogenicity island gene regulator (PigR)—activates FPI transcription and thus is essential for virulence. Intriguingly, the second messenger, guanosine–tetraphosphate (ppGpp), which is produced during infection, is also involved in coordinating Francisella virulence; however, its role has been unclear. Here we identify MglA–SspA as a novel ppGpp-binding complex and describe structures of apo- and ppGpp-bound MglA–SspA. We demonstrate that MglA–SspA, which binds RNA polymerase (RNAP), also interacts with the C-terminal domain of PigR, thus anchoring the (MglA–SspA)–RNAP complex to the FPI promoter. Furthermore, we show that MglA–SspA must be bound to ppGpp to mediate high-affinity interactions with PigR. Thus, these studies unveil a novel pathway different from those described previously for regulation of transcription by ppGpp. The data also indicate that F. tularensis pathogenesis is controlled by a highly interconnected molecular circuitry in which the virulence machinery directly senses infection via a small molecule stress signal.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Radiation-Hardened Circuitry Using Mask-Programmable Analog Arrays: Report 3

As the recent accident at Fukushima Daiichi so vividly demonstrated, telerobotic technologies capable of withstanding high radiation environments need to be readily available to enable operations, repair, and recovery under severe accident scenarios when human entry is extremely dangerous or not possible. Telerobotic technologies that enable remote operation in high dose rate environments have undergone revolutionary improvement over the past few decades. However, much of this technology cannot be employed in nuclear power environments because of the radiation sensitivity of the electronics and the organic insulator materials currently in use. This is a report of the activities involving Task 3 of the Nuclear Energy Enabling Technologies (NEET) 2 project Radiation Hardened Circuitry Using Mask-Programmable Analog Arrays. Evaluation of the performance of the system for both pre- and post-irradiation as well as operation at elevated temperature will be performed. Detailed performance of the system will be documented to ensure the design meets requirements prior to any extended evaluation. A suite of tests will be developed which will allow evaluation before and after irradiation and during temperature. Selection of the radiation exposure facilities will be determined in the early phase of the project. Radiation exposure will consist of total integrated dose (TID) up to 200 kRad or above with several intermediate doses during test. Dose rates will be in various ranges determined by the facility that will be used with a target of 30 kRad/hr. Many samples of the pre-commercial devices to be used will have been tested in previous projects to doses of at least 300 kRad and temperatures up to 125C. The complete systems will therefore be tested for performance at intermediate doses. Extended temperature testing will be performed up to the limit of the commercial sensors. The test suite performed at each test point will consist of operational testing of the three basic measurement functions plus electronic functional testing (power dissipation, voltage offset changes, noise variations, etc.). This suite will be developed as part of this task.

42 ENGINEERING↗
DOE OSTI2014

Radiation-Hardened Circuitry Using Mask-Programmable Analog Arrays (September 2014 Milestone Report)

This is a report of the activities involving Task 2 of the NEET 2 project Radiation Hardened Circuitry Using Mask-Programmable Analog Arrays. Using the analog blocks available in our currently pre-configured Via-Configured Array (VCA), we will perform a detailed schematic design of our system to include the signal-processing blocks for temperature, radiation and pressure. Control and data acquisition will be implemented with the Spartan-6 Field-Programmable Gate Array (FPGA) as well as wired serial communications with a remote computer to be used with this project. In addition, batteries and associated voltage regulators will be selected for powering the system. Fabrication may include a polyimide, printed circuit board (PCB) for improved radiation and temperature tolerance. The PCB will go through a layout process by one of the organizations we utilize for this function and be fabricated by another external vendor. Population of the system board will be performed using one of our in-house technicians or an outside vendor we commonly use. Five prototype systems (sensors, electronics board, battery power supply, and personal computer (PC) serial communications port) will be constructed to support the testing objectives of this work. Quality assurance will be performed at each step by both the submitters and the vendors.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Radiation-Hardened Circuitry Using Mask-Programmable Analog Arrays. Final Report

As the recent accident at Fukushima Daiichi so vividly demonstrated, telerobotic technologies capable of withstanding high radiation environments need to be readily available to enable operations, repair, and recovery under severe accident scenarios where human entry is extremely dangerous or not possible. Telerobotic technologies that enable remote operation in high dose rate environments have undergone revolutionary improvement over the past few decades. However, much of this technology cannot be employed in nuclear power environments due the radiation sensitivity of the electronics and the organic insulator materials currently in use. This is the final report of the activities involving the NEET 2 project Radiation Hardened Circuitry Using Mask-Programmable Analog Arrays. We present a detailed functional block diagram of the proposed data acquisition system, the thought process leading to technical decisions, the implemented system, and the tested results from the systems. This system will be capable of monitoring at least three parameters of importance to nuclear reactor monitoring: temperature, radiation level, and pressure.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Circuitry Design for ChIMES AC Drive Coil

This paper describes the technical aspects for development of the function generator and power amplifier components of the AC Drive coil on the ChIMES sensor. This will significantly aid in miniaturization of the entire sensor system. This paper only documents the two components mentioned, however with the design specifications laid out here, the rest of the circuitry can be miniaturized and made to be compatible with these components more easily than could be done previously.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1965

Use of tear ring permits repair of sealed module circuitry

Improved packaging technique for modular electronic circuitry utilizes a tear ring which may be removed for repair and resealed. The tear ring is put over the container and header to which the electronic circuit assembly has been attached.

Source record↗
NASA NTRS1966

Rugged microelectronic module package supports circuitry on heat sink

Rugged module package for thin film hybrid microcircuits incorporated a rigid, thermally conductive support structure, which serves as a heat sink, and a lead wire block in which T-shaped electrical connectors are potted. It protects the circuitry from shock and vibration loads, dissipates internal heat, and simplifies electrical connections between adjacent modules.

Johnson, A. L.↗
NASA NTRS1966

Logic circuitry used to automatically test shielded cables

Automatic cable tester checks multiple shielded conductors assembly cable connections. The tester uses logic circuitry to sequentially test all conductors and their shields to reveal any connection error in a GO-NO GO test.

Dibb, G.↗