Robust Containment Queries over Trimmed NURBS Surfaces via Generalized Winding Numbers
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Computer science↗
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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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Data from: Coupled machine learning-ecosystem ensemble models substantially improve predictions of nitrous oxide (N 2 O) fluxes from US croplands
Nitrous oxide (N₂O) is a potent and persistent greenhouse gas, with rising atmospheric concentrations driven in part by inefficient use of synthetic nitrogen (N) fertilizers in agriculture. Predicting soil N₂O emissions is challenging due to high spatial and temporal variability arising from complex soil biogeochemical processes. Process-based ecosystem models and standalone machine learning (ML) approaches without extensive site-specific calibration often miss high emission episodes. Here, we show how an Ensemble Modeling System (EMS) based on outputs from an ensemble of ecosystem models coupled to an ensemble of ML models can improve predictions and understanding of N2O fluxes from US cropland. Trained and validated on approximately 12,000 N2O chamber measurements at 17 U.S. Midwest sites (six crops, 35 management practices), the EMS accurately predicted daily fluxes of N2O at both training (R² = 0.84, RMSE = 16.4 g N ha⁻¹ d⁻¹) and held-out testing sites (R² = 0.84, RMSE = 6.2 g N ha⁻¹ d⁻¹). Analyses identified six dominant N₂O drivers: soil organic carbon (SOC), NH₄⁺, NO₃⁻, water-filled pore space (WFPS), soil temperature, and biomass production. Wet, warm soils produced large N₂O peaks only with sufficient SOC and mineral N; in low-SOC soils, fluxes remained low. Incorporating these drivers into process-based models might significantly improve their predictive capacity. The EMS demonstrates a strong potential to predict N₂O fluxes at unseen sites, enabling more reliable regional inventories, improved gap-filling where measurements are sparse, and enhanced understanding of mechanisms to advance targeted mitigation strategies in food, feed, and bioenergy crops.
agricultural sciences↗
Computing methods in optimization problems - Gradient methods for the optimization of dynamic system parameters by hybrid computation
Gradient methods for optimization of dynamic system parameters by hybrid computation
HYBRID COMPUTER↗
Review of boundary-layer studies carried out at the Computational Center of Moscow State University
Review of numerical computations for boundary layer problems
COMPUTATION↗
Astrodynamics, guidance and control review, number 1
Summary of studies on guidance techniques and control equipment, spacecraft computers, and mathematical methods for optimal control of spacecraft and launch vehicles
Source record↗
Identification in automatic control systems
Automatic control system identification with respect to optimality criteria, mathematical models, computing techniques and input signals
Balakrishnan, A. V.↗
An automatic guidance concept for VTOL aircraft
V/STOL aircraft automatic flight control, guidance and navigation by onboard computer, discussing mathematical model and simulation results
Bryson, A. E., Jr.↗
Theoretical and applied mathematics: A compilation
Compilation of papers on applications of mathematics and computer programs for industry related problems
Source record↗
Advanced study of video signal processing in low signal to noise environments
A generalized mathematical and computer model of the revised Apollo television system was developed and used to determine spectral compatibility with the overall Apollo communication system. In particular the effects of the change to commercial television format from slow-scan black and white on the principal telemetering subcarriers was analyzed. Experimental data was obtained from MSC telemetry division confirming the analytical results.
Garden, F.↗
Advances in engineering science, volume 2
Papers are presented dealing with structural dynamics; structural synthesis; and the nonlinear analysis of structures, structural members, and composite structures and materials. Applications of mathematics and computer science are included.
Source record↗
JPL basic research review
Current status, projected goals, and results of 49 research and advanced development programs at the Jet Propulsion Laboratory are reported in abstract form. Areas of investigation include: aerodynamics and fluid mechanics, applied mathematics and computer sciences, environment protection, materials science, propulsion, electric and solar power, guidance and navigation, communication and information sciences, general physics, and chemistry.
Source record↗
Hydraulic dynamic analysis
Computer program mathematically describes complete hydraulic systems to study their dynamic performance. Program employs subroutines that simulate components of hydraulic system, which are then controlled by main program. Program is useful to engineers working with detailed performance results of aircraft, spacecraft, or similar hydraulic systems.
Gale, R. L.↗
Development of flat-plate solar collectors for the heating and cooling of buildings: Executive summary
An efficient, low cost, flat-plate solar collector was developed. Computer aided mathematical models of the heat process in the collector were used in defining absorber panel configuration; determining insulation thickness; and in selecting the number, spacing, and material of the covers. Prototypes were built and performance tested. Data from simulated operation of the collector are compared with predicted loads from a number of locations to determine the degree of solar utilization.
Source record↗
Continuum modeling of three-dimensional truss-like space structures
A mathematical and computational analysis capability has been developed for calculating the effective mechanical properties of three-dimensional periodic truss-like structures. Two models are studied in detail. The first, called the octetruss model, is a three-dimensional extension of a two-dimensional model, and the second is a cubic model. Symmetry considerations are employed as a first step to show that the specific octetruss model has four independent constants and that the cubic model has two. The actual values of these constants are determined by averaging the contributions of each rod element to the overall structure stiffness. The individual rod member contribution to the overall stiffness is obtained by a three-dimensional coordinate transformation. The analysis shows that the effective three-dimensional elastic properties of both models are relatively close to each other.
Nayfeh, A. H.↗
Platform motion for fighter simulations
The reported investigation is concerned with aspects of 'realistic' cue generation and evaluation. 'Realistic' cues are defined to mean cues that are representative of an aircraft, that are of sufficient magnitude to be sensed, that are in the proper direction arriving at the proper time, and yet that are within the presentation capabilities of the washout/synergistic platform system. Attention is given to the aircraft mathematical model, computer implementation, cockpit hardware, visual display, the motion system, vertical acceleration, longitudinal acceleration and pitch rate, and lateral acceleration and roll rate. The motion cues for fighter aircraft produced by Langley nonlinear adaptive washout/synergistic motion base system are found to be unacceptable in the roll axis representation. However, a method for producing potentially realistic roll cues is identified.
Parrish, R. V.↗
Geometric model and analysis of rod-like large space structures
The application of geometrical schemes to large sphere antenna reflectors was investigated. The purpose of these studies is to determine the shape and size of flat segmented surfaces which approximate general shells of revolution and in particular spherical and paraboloidal reflective surfaces. The extensive mathematical and computational geometry analyses of the reflector resulted in the development of a general purpose computer program. This program is capable of generating the complete design parameters of the dish and can meet stringent accuracy requirements. The computer program also includes a graphical self contained subroutine which graphically displays the required design.
Nayfeh, A. H.↗
Geometric modeling and analysis of large latticed surfaces
The application of geometrical schemes, similar to geodesic domes, to large spherical antenna reflectors was investigated. The shape and size of flat segmented latticed surfaces which approximate general shells of revolution, and in particular spherical and paraboloidal reflective surfaces, were determined. The extensive mathematical and computational geometric analyses of the reflector resulted in the development of a general purpose computer program capable of generating the complete design parameters of the dish. The program also includes a graphical self contained subroutine for graphic display of the required design.
Nayfeh, A. H.↗
The 1980 summer research fellowship program
The problem of incorporating visual input into robot systems is described. The photochemistry of the stratosphere, particularly possible permutations of the ozone layer, is discussed. Photoelectrochemical properties of metal thio-hypodiphosphates are investigated. Extreme eigenvalues are computed by the Lancqos approach. The rotational Raman spectra of the molecular atmosphere is studied. A computer operated mathematical symbolic manipulation system is described. Preparation of polycrystalline semiconductor electrodes of tungsten and molybdenum dichalcogenides is received.
Darden, G. C.↗