Search NASA⌕ Search

SEARCH · Search NASA

Results for “Performance analytics”

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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Analytical Review of Exploration Extravehicular Mobility Unit Heat Rejection Performance

The Primary Thermal Control Loop (PTCL) in the Exploration Extravehicular Mobility Unit (xEMU) uses a Spacesuit Water Membrane Evaporator (SWME) to provide cooling for the crew member and spacesuit avionics. A secondary emergency cooling system, the Auxiliary Thermal Control Loop (ATCL), also uses a smaller version of the SWME, called the Mini-ME, in the event of a failure in the primary system. These are integral to the comfort of the crew member (through heat rejection) during an Extravehicular Activity (EVA). This paper examines the effectiveness of the heat rejection of the PTCL and the ATCL during thermal vacuum testing and the absolute limit of heat rejection to maintain an approximately 10C outlet temperature. During this thermal vacuum test, the PTCL was taken from a heat input of 0W up to 900W, far past the design point, and the ATCL was tested from 0W to 300W. Testing showed that the PTCL and the ATCL can maintain crew member outlet temperature throughout an entire 8-hour thermally controlled EVA environment (hot and cold). The results and effectiveness of the test will be detailed throughout this paper for all EVAs (whether a full mapping profile or a standard continuous heat load).

PLSS↗
NASA NTRS2020

Machine Learning-Based Predictive Analytics for Aircraft Engine Conceptual Design

Big data and artificial intelligence/machine learning are transforming the global business environment. Data is now the most valuable asset for enterprises in every industry. Companies are using data-driven insights for competitive advantage. With that, the adoption of machine learning-based data analytics is rapidly taking hold across various industries, producing autonomous systems that support human decision-making. This work explored the application of machine learning to aircraft engine conceptual design. Supervised machine-learning algorithms for regression and classification were employed to study patterns in an existing, open-source database of production and research turbofan engines, and resulting in predictive analytics for use in predicting performance of new turbofan designs. Specifically, the author developed machine learning-based analytics to predict cruise thrust specific fuel consumption (TSFC) and core sizes of high-efficiency turbofan engines, using engine design parameters as the input. The predictive analytics were trained and deployed in Keras, an open-source neural networks application program interface (API) written in Python, with Google’s TensorFlow (an open source library for numerical computation) serving as the backend engine. The promising results of the predictive analytics show that machine-learning techniques merit further exploration for application in aircraft engine conceptual design.

deep-learning↗
NASA NTRS1994

ATAMM enhancement and multiprocessing performance evaluation

The algorithm to architecture mapping model (ATAAM) is a Petri net based model which provides a strategy for periodic execution of a class of real-time algorithms on multicomputer dataflow architecture. The execution of large-grained, decision-free algorithms on homogeneous processing elements is studied. The ATAAM provides an analytical basis for calculating performance bounds on throughput characteristics. Extension of the ATAMM as a strategy for cyclo-static scheduling provides for a truly distributed ATAMM multicomputer operating system. An ATAAM testbed consisting of a centralized graph manager and three processors is described using embedded firmware on 68HC11 microcontrollers.

Stoughton, John W.↗
NASA NTRS1973

Long life performance predictions of SiGe MHW-RTG.

Recent experimental investigations at JPL, Resalab and GGA are incorporated into an analytical model which predicts generator performance over long time periods. The important aging mechanisms considered are degradation in foil insulation conductivity due to reactions with Si sublimed from the hot shoe and SiO2 from the astroquartz layers; changes in hot shoe dimensions due to Si sublimation; changes in leg dimensions due to SiGe sublimation; baffling factors which are applied to the legs to correct the free sublimation model for various effects such as geometry, reactions with the astroquartz wrapping, and hot shoe Si generation; new bulk property changes due to dopant precipitation; and changes in radiation heat exchange due to gap streaming as leg material sublimes.

Caputo, R. S.↗
NASA NTRS1975

Application of active control technology to aircraft ride smoothing

Prototype Ride Smoothing System (RSSs) were synthesized for flight testing aboard the National Aeronautics and Space Administration General Purpose Airborne Simulator (GPAS). The systems were designed to meet comprehensive criteria including passenger comfort and aircraft handling qualities considerations. System performance estimates based on analytic expressions were compared to estimates derived from digital calculations. The effect of RSSs on pilot workload during ILS approach in turbulence was examined in a fixed-base simulator. A limited number of flights were conducted to verify predicted RSS performance. Results of these experiments indicate that RSSs reduce pilot workload and increase passenger comfort while maintaining handling qualities.

Jacobson, I. D.↗
NASA NTRS1976

Nozzle designs with pitch precursor ablatives

Recent developments in carbon phenolic ablatives for solid rocket motor nozzles have yielded a pitch precursor carbon fiber offering significant raw material availability and cost saving advantages as compared to conventional rayon precursor material. This paper discusses the results of an experimental program conducted to assess the thermal performance and characterize the thermal properties of pitch precursor carbon phenolic ablatives. The end result of this program is the complete thermal characterization of pitch fabric, pitch mat, hybrid pitch/rayon fabric and pitch mat molding compound. With these properties determined an analytic capability now exists for predicting the thermal performance of these materials in rocket nozzle liner applications. Further planned efforts to verify material performance and analytical prediction procedures through actual rocket motor firings are also discussed.

Blevins, H. R.↗
NASA NTRS1975

Performance analysis of wideband data and television channels

Several aspects are discussed of space shuttle communications, including the return link (shuttle-to-ground) relayed through a satellite repeater (TDRS). The repeater exhibits nonlinear amplification and an amplitude-dependent phase shift. Models were developed for various link configurations, and computer simulation programs based on these models are described. Certain analytical results on system performance were also obtained. For the system parameters assumed, the results indicate approximately 1 db degradation relative to a link employing a linear repeater. While this degradation is dependent upon the repeater, filter bandwidths, and modulation parameters used, the programs can accommodate changes to any of these quantities. Thus the programs can be applied to determine the performance with any given set of parameters, or used as an aid in link design.

Geist, J. M.↗
NASA NTRS1976

Cube corner retroreflector test and analysis

Cube corner retroreflectors with nominal dihedral angles of 90 deg 0 min 1.5 sec were fabricated, tested, and analyzed to determine the return energy in the annular ring of the far field diffraction pattern required by the Laser Geodynamic Satellite. Performance was assessed for variations in the dihedral angles, optical surfaces, and thermal environment. Despite relatively high independent axial and radial sensitivities, the changes caused by the anticipated thermal environment were found to be negligible; however, there were substantial variations between the analytical predictions and measured performance.-

Zurasky, J. L.↗
NASA NTRSDate not supplied

Aviary: An Open-Source Multidisciplinary Design, Analysis, and Optimization Tool for Modeling Aircraft With Analytic Gradients

Demands on aircraft design methods in recent years have begun to require increasingly higher amounts of coupling between disciplines and have also begun to require optimization in order to satisfy competing objectives involving large numbers of parameters that define unconventional configurations. These expanding requirements have amplified a need for new and improved aircraft design, analysis, and optimization codes that are capable of performing coupled design exploiting analytic gradients where possible. Aviary is a multidisciplinary design optimization and analysis framework which allows for tightly coupled simultaneous aircraft and subsystem design using analytic gradients. Aviary has employed the methods of two legacy aircraft analysis tools to provide native analytically differentiated calculations for five different disciplines, and it also has the ability to couple in external discipline analysis tools, whether or not those tools can provide analytic gradients. Preliminary examples and modeling efforts have shown Aviary’s ability to effectively model novel concepts and explore large and non-intuitive design spaces. Finally, a multi-level user interface in Aviary creates an easy entry point for users with any level of multidisciplinary design, analysis, and optimization experience.

multidisciplinary↗
NASA NTRS1981

Comments on the Leimanis solution of self-excited rigid body

An attempt is made to apply the solutions contained in a book by Leimanis (1965), which includes the Bodewadt solution, to the performance assessment of the Galileo spacecraft during spin up and spin down maneuvers. Because the Galileo is not precisely symmetric, however, the Bodewadt solution fails to achieve the desired accuracy for useful analysis. It is noted that in the case of the Leimanis solution, the analytic results are incorrect for theoretical reasons. In order to remedy this situation, analytic solutions are developed which satisfy the criterion of high accuracy and provide a useful analytic tool for the performance assessment and maneuver analysis of the Galileo spacecraft and many similar near symmetric spinning spacecraft. Simulation results suggest the relative accuracies of the Bodewadt solution and the author's solution, while the restricted regions of validity of the Leimanis solution are clearly indicated.

Longuski, J. M.↗
NASA NTRS1992

Advanced information processing system: The Army fault tolerant architecture conceptual study. Volume 2: Army fault tolerant architecture design and analysis

Described here is the Army Fault Tolerant Architecture (AFTA) hardware architecture and components and the operating system. The architectural and operational theory of the AFTA Fault Tolerant Data Bus is discussed. The test and maintenance strategy developed for use in fielded AFTA installations is presented. An approach to be used in reducing the probability of AFTA failure due to common mode faults is described. Analytical models for AFTA performance, reliability, availability, life cycle cost, weight, power, and volume are developed. An approach is presented for using VHSIC Hardware Description Language (VHDL) to describe and design AFTA's developmental hardware. A plan is described for verifying and validating key AFTA concepts during the Dem/Val phase. Analytical models and partial mission requirements are used to generate AFTA configurations for the TF/TA/NOE and Ground Vehicle missions.

Harper, R. E.↗
NASA NTRS1995

Space Life-Support Engineering Program

This report covers the seventeen months of work performed under an extended one year NASA University Grant awarded to Iowa State University to perform research on topics relating to the development of closed-loop long-term life support systems with the initial principal focus on space water management. In the first phase of the program, investigators from chemistry and chemical engineering with demonstrated expertise in systems analysis, thermodynamics, analytical chemistry and instrumentation, performed research and development in two major related areas; the development of low-cost, accurate, and durable sensors for trace chemical and biological species, and the development of unsteady-state simulation packages for use in the development and optimization of control systems for life support systems. In the second year of the program, emphasis was redirected towards concentrating on the development of dynamic simulation techniques and software and on performing a thermodynamic systems analysis, centered on availability or energy analysis, in an effort to begin optimizing the systems needed for water purification. The third year of the program, the subject of this report, was devoted to the analysis of the water balance for the interaction between humans and the life support system during space flight and exercise, to analysis of the cardiopulmonary systems of humans during space flight, and to analysis of entropy production during operation of the air recovery system during space flight.

Seagrave, Richard C.↗
NASA NTRS2014

Preparing Earth Data Scientists for 'The Sexiest Job of the 21st Century'

What Exactly do Earth Data Scientists do, and What do They Need to Know, to do It? There is not one simple answer, but there are many complex answers. Data Science, and data analytics, are new and nebulas, and takes on different characteristics depending on: The subject matter being analyzed, the maturity of the research, and whether the employed subject specific analytics is descriptive, diagnostic, discoveritive, predictive, or prescriptive, in nature. In addition, in a, thus far, business driven paradigm shift, university curriculums teaching data analytics pertaining to Earth science have, as a whole, lagged behind, andor have varied in approach.This presentation attempts to breakdown and identify the many activities that Earth Data Scientists, as a profession, encounter, as well as provide case studies of specific Earth Data Scientist and data analytics efforts. I will also address the educational preparation, that best equips future Earth Data Scientists, needed to further Earth science heterogeneous data research and applications analysis. The goal of this presentation is to describe the actual need for Earth Data Scientists and the practical skills to perform Earth science data analytics, thus hoping to initiate discussion addressing a baseline set of needed expertise for educating future Earth Data Scientists.

data analytics↗
NASA NTRS1971

Combustion stabilization with acoustic cavities.

An experimental and analytical study has been performed to develop the technology necessary for effective use of acoustic cavities to suppress acoustic modes of combustion instability. An unbaffled variation of the LM ascent engine has been made dynamically stable with acoustic cavities only; five different cavity configurations were found sufficient to produce dynamic stability. An analytical model was developed to calculate the damping contributed by the cavity. Further, subscale tests were made to determine the nonlinear acoustic impedance of these cavities.

Oberg, C. L.↗
NASA NTRS1978

Effect of thermal barrier coatings on the performance of steam and water-cooled gas turbine/steam turbine combined cycle system

An analytical study was made of the performance of air, steam, and water-cooled gas-turbine/steam turbine combined-cycle systems with and without thermal-barrier coatings. For steam cooling, thermal barrier coatings permit an increase in the turbine inlet temperature from 1205 C (2200 F), resulting in an efficiency improvement of 1.9 percentage points. The maximum specific power improvement with thermal barriers is 32.4 percent, when the turbine inlet temperature is increased from 1425 C (2600 F) to 1675 C (3050 F) and the airfoil temperature is kept the same. For water cooling, the maximum efficiency improvement is 2.2 percentage points at a turbine inlet temperature of 1683 C (3062 F) and the maximum specific power improvement is 36.6 percent by increasing the turbine inlet temperature from 1425 C (2600 F) to 1730 C (3150 F) and keeping the airfoil temperatures the same. These improvements are greater than that obtained with combined cycles using air cooling at a turbine inlet temperature of 1205 C (2200 F). The large temperature differences across the thermal barriers at these high temperatures, however, indicate that thermal stresses may present obstacles to the use of coatings at high turbine inlet temperatures.

Nainiger, J. J.↗
NASA NTRS1986

Summary of AH-1G flight vibration data for validation of coupled rotor-fuselage analyses

Under a NASA research program designated DAMVIBS (Design Analysis Methods for VIBrationS), four U. S. helicopter industry participants (Bell Helicopter, Boeing Vertol, McDonnell Douglas Helicopter, and Sikorsky Aircraft) are to apply existing analytical methods for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. Bell Helicopter, as the manufacturer of the AH-1G, was asked to provide pertinent rotor data and to collect the OLS flight vibration data needed to perform the correlations. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM) developed by Bell which has been extensively documented and correlated with ground vibration tests.The AH-1G FEM was provided to each of the participants for use in their coupled rotor-fuselage analyses. This report describes the AH-1G OLS flight test program and provides the flight conditions and measured vibration data to be used by each participant in their correlation effort. In addition, the mechanical, structural, inertial and aerodynamic data for the AH-1G two-bladed teetering main rotor system are presented. Furthermore, modifications to the NASTRAN FEM of the fuselage structure that are necessary to make it compatible with the OLS test article are described. The AH-1G OLS flight test data was found to be well documented and provide a sound basis for evaluating currently existing analysis methods used for calculation of coupled rotor-fuselage vibrations.

Dompka, R. V.↗
NASA NTRSDate not supplied

Hopping with an Adaptive Hop Probability Distribution

Monotonic Basin Hopping (MBH) is a stochastic global search technique that may be used to design complex interplanetary trajectories. Previous research on MBH empirically demonstrated that a bi-polar Pareto distribution is an effective way to generate search “hops.” However, no analytical foundation exists to explain this performance. In this work we provide the beginning of that analytical foundation and also introduce a new variant of MBH that uses an adaptive probability distribution to generate the hops. The technique is demonstrated on historical interplanetary trajectory design problems.

A C Englander↗