Search NASA⌕ Search

SEARCH · Search NASA

Results for “System Analysis Module”

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 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Development Status of the WetLab-2 Project: New Tools for On-orbit Real-time Quantitative Gene Expression.

The primary objective of NASA Ames Research Centers WetLab-2 Project is to place on the ISS a research platform to facilitate gene expression analysis via quantitative real-time PCR (qRT-PCR) of biological specimens grown or cultured on orbit. The WetLab-2 equipment will be capable of processing multiple sample types ranging from microbial cultures to animal tissues dissected on-orbit. In addition to the logistical benefits of in-situ sample processing and analysis, conducting qRT-PCR on-orbit eliminates the confounding effects on gene expression of reentry stresses and shock acting on live cells and organisms. The system can also validate terrestrial analyses of samples returned from ISS by providing quantitative on-orbit gene expression benchmarking prior to sample return. The ability to get on orbit data will provide investigators with the opportunity to adjust experimental parameters for subsequent trials based on the real-time data analysis without need for sample return and re-flight. Finally, WetLab-2 can be used for analysis of air, surface, water, and clinical samples to monitor environmental contaminants and crew health. The verification flight of the instrument is scheduled to launch on SpaceX-5 in Aug. 2014.Progress to date: The WetLab-2 project completed a thorough study of commercially available qRT-PCR systems and performed a downselect based on both scientific and engineering requirements. The selected instrument, the Cepheid SmartCycler, has advantages including modular design (16 independent PCR modules), low power consumption, and rapid ramp times. The SmartCycler has multiplex capabilities, assaying up to four genes of interest in each of the 16 modules. The WetLab-2 team is currently working with Cepheid to modify the unit for housing within an EXPRESS rack locker on the ISS. This will enable the downlink of data to the ground and provide uplink capabilities for programming, commanding, monitoring, and instrument maintenance. The project is currently designing a module that will lyse the cells and extract RNA of sufficient quality for use in qRT-PCR reactions while using a housekeeping gene to normalize RNA concentration and integrity. Current testing focuses on two promising commercial products and chemistries that allow for RNA extraction with minimal complexity and crew time.

quantitative PCR↗
NASA NTRS1972

Modular space station phase B extension preliminary system design. Volume 7: Ancillary studies

Sortie mission analysis and reduced payloads size impact studies are presented. In the sortie mission analysis, a modular space station oriented experiment program to be flown by the space shuttle during the period prior to space station IOC is discussed. Experiments are grouped into experiment packages. Mission payloads are derived by grouping experiment packages and by adding support subsystems and structure. The operational and subsystems analyses of these payloads are described. Requirements, concepts, and shuttle interfaces are integrated. The sortie module/station module commonality and a sortie laboratory concept are described. In the payloads size analysis, the effect on the modular space station concept of reduced diameter and reduced length of the shuttle cargo bay is discussed. Design concepts are presented for reduced sizes of 12 by 60 ft, 14 by 40 ft, and 12 by 40 ft. Comparisons of these concepts with the modular station (14 by 60 ft) are made to show the impact of payload size changes.

Jones, A. L.↗
NASA NTRS2018

NASA Pilot-Engaged Expert Response Using IBM Watson Technology: Prototype Evaluation of Knowledge Retrieval System

NASA Langley Research Center and IBM have been investigating the use of IBM Watson technology in aerospace research and development. One application of Watson technology is the Pilot-Engaged Expert Response (PEER) use case. The PEER system is envisioned as an in-cockpit advisor that will act as a source of situationally-relevant information for pilots and other flight crew members to assist in decision making about real-time events and situations that arise in the course of aircraft operations. PEER will make available vast stores of knowledge and information quickly and directly, putting important informational resources where they are needed most. IBM has worked with NASA to develop an architecture and articulate a roadmap for the development of the PEER system. That vision is built around Watson Discovery Advisor (WDA) software solution, derived from IBM's Jeopardy!-winning automatic question answering system. PEER makes use of WDA's sophisticated question-answering capabilities as its core, adding important User Interface components and other customizations for the cockpit environment, including communication with flight systems and other external data sources. The development plan for PEER includes four development stages, with the current project constituting the first phase. In this project, a prototype instance of PEER was successfully adapted to the aviation domain, enabling users to ask questions about aviation topics and receive useful and accurate answers to these questions. Major tasks accomplished include the development of procedures for domain adaptation through automatic lexicon extraction from domain glossaries; generation of question-answer training data which was used to train the system; and assessment of the effectiveness of domain adaptation, which showed a dramatic improvement in the ability of the PEER system to answer domain-relevant questions. In addition, the vision for the PEER system was pushed forward by the articulation of a plan for the automatic enhancement of question-answering with contextual information. This initial phase focused on two main goals: 1) the targeted domain adaptation of the underlying WDA system to the aviation domain; and, 2) the design of the software systems needed to leverage flight-contextual data. Domain adaptation of the WDA system proceeds via three main activities: Domain data ingestion, lexical customization and model training. A textual corpus consisting of 1,147 individual documents with more than 7.5 million words of text was ingested into the system and this served as the basis of all further development. A domain lexicon of over 3,500 aviation-domain terms was semi-automatically generated from domain documents and used to train the system. In addition, a set of over 500 question-answer (QA) pairs relevant to the PEER use case was developed; these were used to train and assess the system. These important first steps established the basis for the PEER system. In addition, steps were taken towards the integration of the PEER system into the cockpit environment with the development of a functional design for the Contextual Data Augmentation (CDA) subsystem. This subsystem brings to bear contextual data to improve system responses. It has three main submodules: the Contextual Data Collection module, the Contextual Data Selection module, and the Contextual QA Augmentation module. These modules form a processing pipeline that addresses the problems associated with automatically integrating information from external resources into the knowledge-retrieval mechanism.

Machine learning↗
NASA NTRS2020

Lessons Learned from Recent Space Flight Assessments

This paper highlights four space flight assessments, each with an important lesson. The first assessment points to the challenge of material substitution for weight saving. Space Shuttle’s external tank stringers were changed from Al 2024 to Al 2090 without comprehensive analysis. Lack of understanding the low Short-Transverse (S-T) strength associated with Al 2090 led to widespread cracking. The second assessment addresses the failure to understand that time-dependent relationships and loading interactions of multiple disciplines can lead to non-conservative results. An aerodynamic test article of the Orion Multi-Purpose Crew Vehicle (MPCV) Launch Abort System (LAS) was analyzed for worst-case single discipline loads, showing positive structural margins. When disciplines were combined with time dependent loading, the analysis resulted in negative margins. The third assessment highlights the pitfalls of putting blind trust in historical architecture. The MPCV re-entry heat shield adopted the Apollo design approach despite fundamental differences between the two designs (e.g., the underlying substructure design, material differences, scale, and geometry). Manufacturing resulted in cracking along seams of the cured MPCV heat shield and produced lower mechanical properties of the Avcoat witness panels. Subsequently, the design was changed to a block architecture, which introduced unperceived technical, cost, and schedule risk. The fourth assessment shows how the lack of a comprehensive investigation of design modifications and inappropriate Finite Element Analyses (FEA) can lead to trouble. A mass reduction campaign eliminated highly critical internal struts on the ISS Node-1 pressurized module based on inadequate and uncorrelated FEA. High strains were noted and ignored as a modeling aberration. A system level high fidelity FEA discovered large plastic strains in the gussets of all four radial ports. These findings initiated a full-scale test campaign, new test correlated assembly-level FEA, and significant design modifications.

James P Smith↗
DOE OSTI2025

Magnetic contribution of itinerant electrons to neutron diffraction in the topological antiferromagnet CeAlGe

We report a neutron diffraction study of the magnetic structure of CeAlGe, a candidate topological semimetal that hosts a noncollinear, multi-𝐤 magnetic phase. By measuring both low- and high-momentum-transfer magnetic Bragg peaks within a single experimental setup, we refine a magnetic structure model based solely on localized Ce moments. This model, which differs from that obtained using only high-𝑄 data, quantitatively reproduces the observed intensities, including the (000) zeroth-order magnetic satellites that are especially sensitive to subtle components of the modulation. While a contribution from itinerant electrons to the zeroth satellite cannot be definitively excluded, our analysis reveals no unambiguous evidence for such effects within experimental uncertainty. The refined magnetic structures exhibit topologically nontrivial winding patterns, derived from the fitted magnetic parameters, that support localized, particle-like spin textures with half-integer topological charges. These features provide a natural microscopic origin for the observed topological Hall effect, establishing CeAlGe as a model system where magnetism and topology are intimately linked.

Magnetic coupling↗
DOE OSTI2020

A Pattern-Recognition-Based Ensemble Data Imputation Framework for Sensors from Building Energy Systems

Building operation data are important for monitoring, analysis, modeling, and control of building energy systems. However, missing data is one of the major data quality issues, making data imputation techniques become increasingly important. There are two key research gaps for missing sensor data imputation in buildings: the lack of customized and automated imputation methodology, and the difficulty of the validation of data imputation methods. In this paper, a framework is developed to address these two gaps. First, a validation data generation module is developed based on pattern recognition to create a validation dataset to quantify the performance of data imputation methods. Second, a pool of data imputation methods is tested under the validation dataset to find an optimal single imputation method for each sensor, which is termed as an ensemble method. The method can reflect the specific mechanism and randomness of missing data from each sensor. The effectiveness of the framework is demonstrated by 18 sensors from a real campus building. The overall accuracy of data imputation for those sensors improves by 18.2% on average compared with the best single data imputation method.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1972

Analysis of space tug operating techniques. Volume 2: Study results

The design requirements for space tug systems and cost analysis of the refurbishment phases are discussed. The vehicle is an integral propulsion stage using liquid hydrogen and liquid oxygen as propellants and is capable of operating either as a fully or a partially autonomous vehicle. Structural features are an integral liquid hydrogen tank, a liquid oxygen tank, a meteoroid shield, an aft conical docking and structural support ring, and a staged combustion main engine. The vehicle is constructed of major modules for ease of maintenance. Line drawings and block diagrams are included to explain the maintenance requirements for the subsystems.

Source record↗
NASA NTRS1986

Evaluation of active thermal control options for Space Station

An analysis of various Space Station (MSS) active thermal control systems options under consideration because of their potential low weight, efficiency and reliability is reported. The study addressed ordinary and diode-action body mounted radiators, thermal storage, the area and pumping power requirements for single-phase cooling of cold plates, and single-phase and two-phase active cooling loops. The base configuration considered was a core MSS formed by four habitable modules on which are mounted heat pipe radiators articulated to be always edge-on to the sun. A simulation was performed which accounted for the available heat sinks, several thermal loads and the heat rejection capability. No benefits were found with diode-action radiators if the solar absorption is 0.1 or less, although diode-action heat pipes will maintain a higher level of performance in the presence of coating degradation. Thermal storage becomes important only with radiator coating degradation. Water can be up to three times as efficient as Freon as a heat transfer medium. Finally, single-phase cooling offers a lower system mass than two-phase cooling if varying temperature heat loads can be accommodated.

Schuster, J. R.↗
NASA NTRS1989

Simulation and analysis of an intermediate frequency (IF) distribution system with applications for Space Station

Simulation and analysis results are described for a wideband fiber optic intermediate frequency distribution channel for a frequency division multiple access (FDMA) system where antenna equipment is remotely located from the signal processing equipment. The fiber optic distribution channel accommodates multiple signals received from a single antenna with differing power levels. Performance parameters addressed are intermodulation degradations, laser noise, and adjacent channel interference, as they impact the overall system design. Simulation results showed that the laser diode modulation level can be allowed to reach 100 percent without considerable degradation. The laser noise must be controlled as to provide a noise floor of less than -90 dBW/Hz. The fiber optic link increases the degradation due to power imbalance yet diminishes the effects of the transmit amplifier nonlinearity. Overall, optimal operation conditions can be found to yield a degradation level of about .1 dB caused by the fiber optic link.

Costello, Thomas A.↗
NASA NTRS1991

Development of a computer algorithm for the analysis of variable-frequency AC drives: Case studies included

The development of computer software for performance prediction and analysis of voltage-fed, variable-frequency AC drives for space power applications is discussed. The AC drives discussed include the pulse width modulated inverter (PWMI), a six-step inverter and the pulse density modulated inverter (PDMI), each individually connected to a wound-rotor induction motor. Various d-q transformation models of the induction motor are incorporated for user-selection of the most applicable model for the intended purpose. Simulation results of selected AC drives correlate satisfactorily with published results. Future additions to the algorithm are indicated. These improvements should enhance the applicability of the computer program to the design and analysis of space power systems.

Kankam, M. David↗
NASA NTRS1995

Heart rate and respiratory rhythm dynamics on ascent to high altitude

OBJECTIVE--To investigate the alterations in autonomic control of heart rate at high altitude and to test the hypothesis that hypoxaemic stress during exposure to high altitude induces non-linear, periodic heart rate oscillations, similar to those seen in heart failure and the sleep apnoea syndrome. SUBJECTS--11 healthy subjects aged 24-64. MAIN OUTCOME MEASURES--24 hour ambulatory electrocardiogram records obtained at baseline (1524 m) and at 4700 m. Simultaneous heart rate and respiratory dynamics during 2.5 hours of sleep by fast Fourier transform analysis of beat to beat heart rate and of an electrocardiographically derived respiration signal. RESULTS--All subjects had resting hypoxaemia at high altitude, with an average oxyhaemoglobin saturation of 81% (5%). There was no significant change in mean heart rate, but low frequency (0.01-0.05 Hz) spectral power was increased (P < 0.01) at high altitude. Time series analysis showed a complex range of non-linear sinus rhythm dynamics. Striking low frequency (0.04-0.06 Hz) heart rate oscillations were observed during sleep in eight subjects at high altitude. Analysis of the electrocardiographically derived respiration signal indicated that these heart rate oscillations correlated with low frequency respiratory oscillations. CONCLUSIONS--These data suggest (a) that increased low frequency power during high altitude exposure is not simply attributable to increased sympathetic modulation of heart rate, but relates to distinctive cardiopulmonary oscillations at approximately 0.05 Hz and (b) that the emergence of periodic heart rate oscillations at high altitude is consistent with an unstable cardiopulmonary control system that may develop on acute exposure to hypoxaemic stress.

Non-NASA Center↗
NASA NTRS2009

Astronaut Thermal Exposure: Re-Entry After Low Earth Orbit Rescue Mission

The STS-125 mission, launched May 11, 2009, is the final servicing mission to the Hubble Space Telescope. The repair mission's EVA tasks are described, including: installing a new wide field camera; installing the Cosmic Origins Spectrograph; repairing the Space Telescope Imaging Spectrograph; installing a new outer blanket layer; adding a Soft Capture and Rendezvous System for eventual controlled deorbit in about 2014; replacing the 'A' side Science Instrument Command and Data Handling module; repairing the Advanced Camera for surveys; and, replacing the rate sensor unit gyroscopes, fine guidance sensors and 3 batteries. Additionally, the Shuttle crew cabin thermal environment is described. A CFD model of per person CO2 demonstrates a discrepancy between crew breathing volume and general mid-deck levels of CO2. A follow-on CFD analysis of the mid-deck temperature distribution is provided. Procedural and engineering mitigation plans are presented to counteract thermal exposure upon reentry to the Earth atmosphere. Some of the procedures include: full cold soak the night prior to deorbit; modifying deck stowage to reduce interference with air flow; and early securing of avionics post-landing to reduce cabin thermal load prior to hatch opening. Engineering mitigation activities include modifying the location of the aft starboard ICUs, eliminating the X3 stack and eliminating ICU exhaust air directed onto astronauts; improved engineering data of ICU performance; and, verifying the adequacy of mid-deck temperature control using CFD models in addition to lumped parameter models. Post-mitigation CFD models of mid-deck temperature profiles and distribution are provided.

Gillis, David B.↗
DOE OSTI2023

Thermal Hydraulic Modeling of an Advanced Nuclear Reactor using open-source MOOSE tools

The aim of this study is to develop model of a small High Temperature Gas cooled Reactor (HTGR) including the balance of plant. This microreactor produces electricity using the thermal power of the nuclear reaction. This work utilizes the MOOSE Multiphysics simulation tools, which are mainly developed at Idaho National Laboratory (INL, Idaho, United States of America). Its thermal-hydraulics and Heat conduction Modules are used to study the fluids behavior in the primary loop and power conversion system and their interactions with the heating structures. More specifically, one verifies that the temperatures, pressures and mass flow rates of the fluids in both loops are consistent and that, at the same time, all the power transfers occur as expected. Moreover, the various mechanical components characteristics (turbine, compressor, pump) are adapted to the reactor operating conditions. This first analysis is conducted using simplified and one-dimensional model for the core. Ultimately, the obtained results are used to build a higher fidelity core model. This step aims to verify that the initial simplified simulation is consistent with the three-dimensional core modeling. In addition, the calculated material temperatures are checked. This study provides a fairly complete model of the thermal hydraulic phenomena for a particular design of High Temperature Gas cooled Reactor.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1998

Simultaneous amplification of terahertz difference frequencies by an injection-seeded semiconductor laser amplifier at 850 nm

Two-frequency operation of an 850 nm semiconductor optical amplifier was achieved by simultaneously injection seeding it with two diode lasers. The two frequencies could be independently amplified without strong interference when they were separated by more than 10 GHz, and the spectral purity was preserved by the amplification process. At frequency differences below 10 GHz, unbalanced two-frequency output was observed, which can be explained by a two-mode interaction driven by the refractive index modulation at the beat frequency. The laser system is suitable for the difference-frequency generation of coherent terahertz radiation in ultra-fast photoconductors or nonlinear optical media.

NASA Discipline Exobiology↗
DOE OSTI2019

Optimal Variable Switching Frequency Scheme to Reduce Loss of Single-Phase Grid-Connected Inverter With Unipolar and Bipolar PWM

Reducing the power loss of a converter without increasing its volume or cost in hardware has always been a much sought-after but challenging goal. This article proposes a comprehensive variable switching frequency (VSF) scheme to improve the overall system efficiency while still meeting a given total harmonic distortion (THD) requirement without any hardware changes, achieved only by changes to the controller. In this article, it is analyzed that for the H-bridge inverter, the inductor copper loss and the switch conduction loss are independent of the switching frequency (SF), while the device switching loss and the inductor core loss are functions of the SF. This article aims at weighting the combined switching loss and inductor core loss for both the unipolar and bipolar modulation techniques, with the constraint on the output THD, which, for fixed passive components, is a function of inductor ripple current that in turn depends on the SF. An optimal VSF scheme is devised through rigorous mathematical analysis of the output ripple component and the SF-dependent losses. In each switching cycle, the inductor ripple current is predicted with the circuit parameters, such as duty cycle, switching period, inductance, and dc voltage, and by implementing the VSF scheme, the current ripple is optimally varied such as to satisfy the THD requirement while reducing the SF-dependent losses. A generalized method to design VSF schemes for any topology and specifications is also presented, which would help future users in designing the VSF controller. A 1-kW H-bridge inverter using SiC MOSFETs and powdered iron/ferrite core has been built to validate the theoretical analysis. Both constant SF (CSF) scheme (200 kHz) and optimal VSF scheme with simple controller modification have been implemented in the experimental prototype using DSP TMS320f28335. Compared with the CSF scheme, the optimal VSF scheme shows a significant improvement in the system efficiency at rated power from 94.7%...

conduction loss↗
DOE OSTI2020

Evaluating Energy Efficiency Opportunities from Connected and Automated Vehicle Deployments Coupled with Shared Mobility in California

Connected and Automated Vehicles (CAVs) can be considered to be a disruptive transportation technology, with the potential to significantly improve overall transportation system efficiency; however, CAVs may increase induce vehicle miles traveled (VMT) and bring on greater energy consumption. Further, shared mobility is another disruptive transportation event that is reshaping our travel patterns. The primary goal of this project was to extensively collect data from vehicles and associated infrastructure equipped with CAV technologies from both real-world experiments and simulation studies mainly deployed in California, and develop a comprehensive framework for evaluating energy efficiency opportunities from large-scale (e.g., statewide) introduction of CAVs and a wide deployment of shared mobility systems in a variety of scenarios. To quantify the combined impact of CAV and shared mobility on travel behavior, traffic performance, and energy efficiency, a unique mesoscopic simulation-based model was developed for mobility and energy efficiency evaluation considering these disruptive transportation technologies. As a complement to existing studies on nationwide evaluation of CAVs’ energy impacts, this project was focused on data collection efforts and CAV applications under congested traffic environments that are frequently experienced on a massive scale across the major metropolitan areas in California. Extensive real-world data collection supplemented with simulation studies were conducted to cover a variety of CAV and shared mobility scenarios, particularly on scenarios less-explored in the existing research. Another key component of this project was to consider the interaction between different CAV technologies and shared mobility models, and the compound effect on energy efficiency. A comprehensive modeling suite was developed to quantify the impact of new mobility technologies on travel behavior and traffic performance. The developed modeling framework includes an energy intensity module, mode choice module and activity generation module that are integrated into an agent-based BEAM simulation platform to perform impact analysis based on a variety of scenarios. In addition, the RouteE model has been upgraded to incorporate the impact of CAVs on traffic flow, VMT and energy intensity, using micro-simulation data collected from both freeways and urban arterials. A novel fundamental influencing factor (FIF) mode choice model was developed to link CAV and shared mobility components with travel behaviors, and adapted into the BEAM-centered model framework. A statewide energy inventory was constructed under various CAV technology deployment scenarios by incorporating datasets and models for predicting vehicle market share and vehicle usage, which are tightly associated with the penetration of shared mobility systems. Based applying this modeling suite to a calibrated network in Riverside California, it was found that cooperative automated driving in general will improve mobility, but automated vehicles, even when deployed in a shared autonomous fleet, will likely bring an increase of VMT (up to 36%) due to mode shifts and deadheading. Ride-hailing vehicles typically have better energy efficiency and a higher share of electric vehicles, which helps offset the negative impact from VMT increases when estimating the system-level energy consumption. In general, simulation results show a 6% increase in energy consumption for the scenarios with an increasing shift to ride-hailing modes. The statewide analysis based on the National Household Travel Survey (NHTS) sample data is consistent with the findings from the Riverside network and validate the developed clustering-prediction modeling methodology. The outcomes from this project will help close the knowledge gap on recognizing the potential performance and energy impacts of a broad deployment of CAV and shared mobility technologies across a wide range of roadway infrastructure with varying levels of congestion. Results from this project: 1) will support policymakers in steering CAV development and deployment towards an energy favorable direction; 2) reduce uncertainties in estimating energy saving opportunities from new mobility technologies and services; 3) increase the confidence of CAV technology investors both on the infrastructure side (i.e., transportation agencies) and on the vehicle side (i.e., OEMs); and 4) expedite the deployment of energy-efficient CAV and shared mobility applications.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Understanding interfacial chemistry of positive bias high-voltage degradation in photovoltaic modules

Photovoltaic module degradation from a high system voltage is a prevalent degradation mode in the field, where the enabling degradation mechanisms are inherently dependent on the voltage bias polarity of the installed system. In this study, the effects of positive bias on module performance are confirmed and the underlying chemical degradation processes are more thoroughly investigated to reveal different degradation pathways from those previously reported in negative bias studies. When cells are under +1000 V stress, crystalline silicon mini-modules with poly(ethylene-co-vinyl acetate) (EVA) encapsulant demonstrated a significant photocurrent loss due to EVA discoloration and delamination from increased chemical reactivity at the front-side EVA/cell metallization interface. Brown discoloration of the EVA encapsulant near the cell gridlines is linked to an electrochemical reaction at the Ag gridlines under hot and humid conditions (85 °C, 85% relative humidity). Chemical compositional analysis using X-ray photoelectron spectroscopy (XPS) confirmed that the discoloration is attributed to the formation of silver sulfide (Ag 2 S) and/or silver oxide (Ag 2 O) species at the EVA/Ag gridline interface. The subsequent migration of Ag ions from the cell gridlines into the bulk of the EVA was evident from XPS depth profiling and optical microscopy. However, the Ag signal was not detected at the EVA/glass interface, inferring limited ionic transport through the nominally 0.45 mm thick encapsulant. For the samples studied herein, the sulfur is believed by the process of elimination to come from the ambient air, diffusing into the module through the permeable polymer backsheet.

14 SOLAR ENERGY↗