Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “manifolds”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Sliding regimes on slow manifolds of systems with fast actuators

In this article the slow manifold of a system with actuator parasitics is used as a sliding surface on which a Variable Structure Controller recovers the qualitative properties of the reduced order, closed loop system obtained from an ideal actuator-based feedback controller design. Illustrative examples are presented, where (1) the simplicity of reduced order singular perturbation design methods; and (2) the robustness of Variable Structure sliding modes, are advantageously combined.

Sira-Ramirez, Hebertt↗
NASA NTRS1988

Flowfield visualization for SSME hot gas manifold

The objective of this research, as defined by NASA-Marshall Space Flight Center, was two-fold: (1) to numerically simulate viscous subsonic flow in a proposed elliptical two-duct version of the fuel side Hot Gas Manifold (HGM) for the Space Shuttle Main Engine (SSME), and (2) to provide analytical support for SSME related numerical computational experiments, being performed by the Computational Fluid Dynamics staff in the Aerophysics Division of the Structures and Dynamics Laboratory at NASA-MSFC. Numerical results of HGM were calculations to complement both water flow visualization experiments and air flow visualization experiments and air experiments in two-duct geometries performed at NASA-MSFC and Rocketdyne. In addition, code modification and improvement efforts were to strengthen the CFD capabilities of NASA-MSFC for producing reliable predictions of flow environments within the SSME.

Roger, Robert P.↗
NASA NTRS1990

LOX manifold tee analysis

A 4000 Hz vibration phenomena was observed during the test firings of several space shuttle main engines (SSME). Experimental studies of this phenomena suggest that the problem might be associated with vortex shedding from the vanes within the LOX tee manifold. The objective of this study was to determine the unsteady, 3-D flow associated with these vanes by computational methods to identify and better understand the 4000 Hz vibration phenomena. A flow solver, FDNS, for the turbulent conservation equations was validated for predicting high frequency vortex dynamics and used to predict 2-D and 3-D flows within the LOX tee. 4000 Hz excitation oscillations were predicted for some flows and the entire 3-D flow structure was predicted for LOX tee flow. The complexity of the flow was revealed by this analysis, and computational methods for predicting these high frequency oscillations in future engine systems were established.

Chen, Yen-Sen↗
NASA NTRS1992

Robotic Welding Of Injector Manifold

Brief report presents history, up through October 1990, of continuing efforts to convert from manual to robotic gas/tungsten arc welding in fabrication of main injector inlet manifold of main engine of Space Shuttle. Includes photographs of welding machinery, welds, and weld preparations. Of interest to engineers considering establishment of robotic-welding facilities.

Gilbert, Jeffrey L.↗
NASA NTRS1993

Generating Grids For Computing Flow In A Manifold

Establishing computer code modified to apply to complicated shapes. Grids for computing flows in manifold of complicated shape generated by use of modified version of geometry module of LWIND computer code. Code adaptable to other computations of flows in different geometries.

Anderson, Peter G.↗
NASA NTRS1998

On the Circulation Manifold for Two Adjacent Lifting Sections

The circulation functional relative to two adjacent lifting sections is studied for two cases. In the first case we consider two adjacent circles. The circulation is computed as a function of the displacement of the secondary circle along the axis joining the two centers and of the angle of attack of the secondary circle, The gradient of such functional is computed by deriving a set of elliptic functions with respect both to their argument and to their Period. In the second case studied, we considered a wing-flap configuration. The circulation is computed by some implicit mappings, whose differentials with respect to the variation of the geometrical configuration in the physical space are found by divided differences. Configurations giving rise to local maxima and minima in the circulation manifold are presented.

Zannetti, Luca↗
NASA NTRS2003

Use of Invariant Manifolds for Transfers Between Three-Body Systems

The Lunar L1 and L2 libration points have been proposed as gateways granting inexpensive access to interplanetary space. To date, only individual solutions to the transfer between three-body systems have been found. The methodology to solve the problem for arbitrary three-body systems and entire families of orbits does not exist. This paper presents the initial approaches to solve the general problem for single and multiple impulse transfers. Two different methods of representing and storing 7-dimensional invariant manifold data are presented. Some particular solutions are presented for the transfer problem, though the emphasis is on developing methodology for solving the general problem.

Beckman, Mark↗
NASA NTRS2004

Representations of Invariant Manifolds for Applications in Three-Body Systems

The Lunar L1 and L2 libration points have been proposed as gateways granting inexpensive access to interplanetary space. To date, only individual solutions to the transfer between three-body systems have been found. The methodology to solve the problem for arbitrary three-body systems and entire families of orbits is currently being studied. This paper presents an initial approach to solve the general problem for single and multiple impulse transfers. Two different methods of representing and storing the invariant manifold data are presented. Some particular solutions are presented for two types of transfer problems, though the emphasis is on developing the methodology for solving the general problem.

Howell, K.↗
NASA NTRS2016

Decision Manifold Approximation for Physics-Based Simulations

With the recent surge of success in big-data driven deep learning problems, many of these frameworks focus on the notion of architecture design and utilizing massive databases. However, in some scenarios massive sets of data may be difficult, and in some cases infeasible, to acquire. In this paper we discuss a trajectory-based framework that quickly learns the underlying decision manifold of binary simulation classifications while judiciously selecting exploratory target states to minimize the number of required simulations. Furthermore, we draw particular attention to the simulation prediction application idealized to the case where failures in simulations can be predicted and avoided, providing machine intelligence to novice analysts. We demonstrate this framework in various forms of simulations and discuss its efficacy.

Wong, Jay Ming↗
DOE OSTI2025

Compressing Vision Transformers in Geospatial Transfer Learning with Manifold-Constrained Optimization

Deploying geospatial foundation models on resource-constrained edge devices demands compact architectures that maintain high downstream performance. However, their large parameter counts and the accuracy loss often induced by compression limit practical adoption.In this work, we leverage manifold-constrained optimization framework DLRT to compress large vision transformer–based geospatial foundation models during transfer learning. By enforcing structured low-dimensional parameterizations aligned with downstream objectives, this approach achieves strong compression while preserving task-specific accuracy. We show that the method outperforms of-the-shelf low-rank methods as LoRA. Experiments on diverse geospatial benchmarks confirm substantial parameter reduction with minimal accuracy loss, enabling high-performing, on-device geospatial models.

Snyder, Thomas [Yale University]↗
NASA NTRS1997

Halo Orbit Generation Using the Center Manifold

In recent years, halo orbits around the Sun-Earth Lagrange points, L1 and L2, have become extremely opular for NASA missions due to the ideal observation environment and low launch energy.

periodic↗
NASA NTRSDate not supplied

Sample Processor for Life on Icy Worlds (SPLIce): Monolithic Manifold-Based System to Recover, Prepare, and Deliver Samples and Standards to Instrumentation Suites for Ocean World Life-Search Missions

A claim of life detection on one of the solar system’s icy ocean worlds would necessitate extraordinarily convincing evidence. Limited energy availability in the oceans of such bodies as Europa and Enceladus argues for microbes as most probable among possible life forms, but evidence of their existence in the surface layers of an icy moon or in a frozen plume ejected into space could take various forms, pointing to instrumentation suites as a preferred means to detect diverse molecular and morphological life indicators. Multiple disparate categories of positive detections could provide truly convincing evidence from samples that may be only a few micro-liters. SPLIce’s Foundation. Teams led by NASA’s Ames Research Center have developed and operated numerous small, live-biology and astrobiology science payloads in space over two decades. Since 2016, we have adapted and augmented their biological sample-handling systems to create compact, robust search-for-life fluidic processors designed to function after a decade or more in transit, in environments with very little gravity and lots of radiation: up to 100’s of kilorads.

Instrumentation suite↗