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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Optimization of Microelectronic Devices for Sensor Applications

The NASA/JPL goal to reduce payload in future space missions while increasing mission capability demands miniaturization of active and passive sensors, analytical instruments and communication systems among others. Currently, typical system requirements include the detection of particular spectral lines, associated data processing, and communication of the acquired data to other systems. Advances in lithography and deposition methods result in more advanced devices for space application, while the sub-micron resolution currently available opens a vast design space. Though an experimental exploration of this widening design space-searching for optimized performance by repeated fabrication efforts-is unfeasible, it does motivate the development of reliable software design tools. These tools necessitate models based on fundamental physics and mathematics of the device to accurately model effects such as diffraction and scattering in opto-electronic devices, or bandstructure and scattering in heterostructure devices. The software tools must have convenient turn-around times and interfaces that allow effective usage. The first issue is addressed by the application of high-performance computers and the second by the development of graphical user interfaces driven by properly developed data structures. These tools can then be integrated into an optimization environment, and with the available memory capacity and computational speed of high performance parallel platforms, simulation of optimized components can proceed. In this paper, specific applications of the electromagnetic modeling of infrared filtering, as well as heterostructure device design will be presented using genetic algorithm global optimization methods.

Cwik, Tom↗
NASA NTRS1989

The use of vestibular models for design and evaluation of flight simulator motion

Quantitative models for the dynamics of the human vestibular system are applied to the design and evaluation of flight simulator platform motion. An optimal simulator motion control algorithm is generated to minimize the vector difference between perceived spatial orientation estimated in flight and in simulation. The motion controller has been implemented on the Vertical Motion Simulator at NASA Ames Research Center and evaluated experimentally through measurement of pilot performance and subjective rating during VTOL aircraft simulation. In general, pilot performance in a longitudinal tracking task (formation flight) did not appear to be sensitive to variations in platform motion condition as long as motion was present. However, pilot assessment of motion fidelity by means of a rating scale designed for this purpose, were sensitive to motion controller design. Platform motion generated with the optimal motion controller was found to be generally equivalent to that generated by conventional linear crossfeed washout. The vestibular models are used to evaluate the motion fidelity of transport category aircraft (Boeing 727) simulation in a pilot performance and simulator acceptability study at the Man-Vehicle Systems Research Facility at NASA Ames Research Center. Eighteen airline pilots, currently flying B-727, were given a series of flight scenarios in the simulator under various conditions of simulator motion. The scenarios were chosen to reflect the flight maneuvers that these pilots might expect to be given during a routine pilot proficiency check. Pilot performance and subjective rating of simulator fidelity was relatively insensitive to the motion condition, despite large differences in the amplitude of motion provided. This lack of sensitivity may be explained by means of the vestibular models, which predict little difference in the modeled motion sensations of the pilots when different motion conditions are imposed.

Bussolari, Steven R.↗
NASA NTRS1981

Structural requirements and technology needs of geostationary platforms

To identify structural requirements and technology needs of the geostationary platforms, two design alternatives are analyzed with respect to utilities accommodation, interface, and strength and stiffness requirements. Alternative 1 is comprised of 6,800 kg (15,000 lb) platform modules, each delivered to low earth orbit (LEO) with an attached orbit transfer vehicle (OTV) in a single Shuttle flight, deployed, and transferred to a geostationary constellation of platforms. Alternative 2 is made up of 16,800 kg (37,000 lb) platform modules, each delivered to LEO, deployed, mated to a 2 stage OTV (delivered to LEO in two additional Shuttle flights) and transferred to GEO for docking with other modules to form a single large platform. The top candidates for deployable structure elements are the expandable truss beam and the Astromast. The beam, fabricated of graphite/epoxy with a designed coefficient of thermal expansion of zero, provides good packaging density and high strength and stiffness per unit weight. The Astromast provides the best packaging density, but lacks the strength and stiffness required for the platform payloads. A graphite/epoxy mast with the Astromast packaging density is an advancement in technology needed for optimizing the geostationary platform designs.

Stone, G. R.↗
NASA NTRS2024

Envisioning an Optimal Network of Space-Based Lasers for Orbital Debris Remediation

The rapid increase in resident space objects, including satellites and orbital debris, poses a significant threat to the safety and sustainability of space missions. This paper explores orbital debris remediation using a network of collaborative space-based lasers, leveraging laser ablation for momentum transfer on debris. A novel delta-v vector analysis framework quantifies the e↵ects of multiple simultaneous laser-to-debris (L2D) engagements by using vector composition of the imparted delta-v vectors. The paper introduces the Concurrent LocationScheduling Problem (CLSP), which optimizes the placement of laser platforms and the scheduling of L2D engagements to maximize debris remediation capacity. Due to the computational complexity of the CLSP, it is decomposed into two sequential subproblems: (1) optimal laser platform locations are determined using the Maximal Covering Location Problem, and (2) a novel integer linear programming-based approach schedules L2D engagements within the network configuration to maximize remediation capacity. Computational experiments are conducted to evaluate the proposed framework’s e↵ectiveness under various mission scenarios, demonstrating key network functions such as collaborative nudging, deorbiting, and just-in-time collision avoidance. A sensitivity analysis further examines how varying the number and distribution of laser platforms a↵ects debris remediation capacity, providing insights into optimizing the performance of space-based laser networks.

David O Williams Rogers↗
NASA NTRS2003

The Promise of Macromolecular Crystallization in Micro-fluidic Chips

Micro-fluidics, or lab on a chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bio-analytical and microscale bio-preparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require equilibrating macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a micro-fluidics platform. More complex optimization methods, where crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a micro-fluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation of crystals as they are grown.

vanderWoerd, Mark↗
NASA NTRS2012

Optimizing Flight Control Software With an Application Platform

Flight controllers in NASA s mission control centers work day and night to ensure that missions succeed and crews are safe. The IT goals of NASA mission control centers are similar to those of most businesses: to evolve IT infrastructure from basic to dynamic. This paper describes Mission Control Technologies (MCT), an application platform that is powering mission control today and is designed to meet the needs of future NASA control centers. MCT is an extensible platform that provides GUI components and a runtime environment. The platform enables NASA s IT goals through its use of lightweight interfaces and configurable components, which promote standardization and incorporate useful solution patterns. The MCT architecture positions mission control centers to reach the goal of dynamic IT, leading to lower cost of ownership, and treating software as a strategic investment.

Smith, Irene Skupniewicz↗
NASA NTRS1975

Data resolution versus forestry classification and modeling

This paper examines the effects on timber stand computer classification accuracies caused by changes in the resolution of remotely sensed multispectral data. This investigation is valuable, especially for determining optimal sensor and platform designs. Theoretical justification and experimental verification support the finding that classification accuracies for low resolution data could be better than the accuracies for data with higher resolution. The increase in accuracy is constructed as due to the reduction of scene inhomogeneity at lower resolution. The computer classification scheme was a maximum likelihood classifier.

Kan, E. P.↗
NASA NTRS1978

Imaging of X-ray aurorae from Spacelab

The Atmospheric X-ray Emission Telescope (AXET) is designed to image and measure the spatial, temporal, and spectral distributions of X-ray aurorae produced in the upper atmosphere by precipitating energetic electrons. The bremsstrahlung-produced X radiation penetrates to stratospheric depths where it can modify ozone, conductivity, and other critical atmospheric parameters. Remote sensing of this radiation from topside will provide vital data on solar-terrestrial relationships and mechanisms that could help trigger tropospheric response to solar activity. The X rays also provide direct information concerning the dynamics of radiation-belt processes within the magnetosphere. AXET is designed to detect sources up to 50 keV and to image them below 25 keV by means of directionally sensitive proportional counters with passive collimators. It will be mounted in the Space Shuttle on a single fixed platform designed to optimize viewing conditions for the anticipated orbits and aspects of early Spacelab missions.

Goldberg, R. A.↗
NASA NTRS1982

Structures: Propulsion interactions and requirements

The dynamics of the interaction of space structures and their propellant systems are outlined. Optimization for a platform type of space structure is discussed. Static and transient loads, propellant accelerations, tolerances, attitude control, and distributed thrust are considered.

Pengelley, C. D.↗
NASA NTRS1986

A high resolution spectrometer for EUV/FUV wavelengths

The most efficient of the various configurations considered for a high-resolution spaceborne spectrometer for point-source astronomy in the 400-1200-A wavelength region which will fit within an envelope defined by the projected Spartan space platform is a multiple Rowland circle spectrograph, with each of four toroidal gratings respectively intercepting a fraction of the primary mirror beam. Each spectrometer can accept a rather slowly diverging beam, reducing grating aberrations, without further efficiency loss due to additional reflections or magnification. The line densities, detector size, pixel size, etc., of the detector for this instrument are dependent on the drift rate of the space platform; a design optimized for an uncorrected 4-arcsec drift is presented.

Hurwitz, Mark↗
NASA NTRS1990

Use of nonlinear design optimization techniques in the comparison of battery discharger topologies for the space platform

A detailed comparison of a boost converter, a voltage-fed, autotransformer converter, and a multimodule boost converter, designed specifically for the space platform battery discharger, is performed. Computer-based nonlinear optimization techniques are used to facilitate an objective comparison. The multimodule boost converter is shown to be the optimum topology at all efficiencies. The margin is greatest at 97 percent efficiency. The multimodule, multiphase boost converter combines the advantages of high efficiency, light weight, and ample margin on the component stresses, thus ensuring high reliability.

Sable, Dan M.↗
NASA NTRS1991

Optimal control/structure integrated design of a flexible space platform with articulated appendages

A complete set of closed form symbolic equations are developed for a 2-D model of a system comprised of a flexible platform with articulated appendages. The system considered has a flexible two link manipulator, with joint compliance, at one end of the flexible platform and an articulated antenna on the other end. The model is formulated using a Lagrangian approach which incorporates homogeneous transformation matrices, similar to those typically seen in the robotics literature, for the kinematic representation. The integrated control/structure design strategy considered emphasizes rapid system response and minimal structural weight. Constraints are included to keep antenna pointing error to a minimum, and at the same time achieve accurate end point positioning of the manipulator with minimal oscillations.

Kelkar, Atul G.↗
NASA NTRS2001

Pre-Hardware Optimization of Spacecraft Image Processing Software Algorithms and Hardware Implementation

Spacecraft telemetry rates have steadily increased over the last decade presenting a problem for real-time processing by ground facilities. This paper proposes a solution to a related problem for the Geostationary Operational Environmental Spacecraft (GOES-8) image processing application. Although large super-computer facilities are the obvious heritage solution, they are very costly, making it imperative to seek a feasible alternative engineering solution at a fraction of the cost. The solution is based on a Personal Computer (PC) platform and synergy of optimized software algorithms and re-configurable computing hardware technologies, such as Field Programmable Gate Arrays (FPGA) and Digital Signal Processing (DSP). It has been shown in [1] and [2] that this configuration can provide superior inexpensive performance for a chosen application on the ground station or on-board a spacecraft. However, since this technology is still maturing, intensive pre-hardware steps are necessary to achieve the benefits of hardware implementation. This paper describes these steps for the GOES-8 application, a software project developed using Interactive Data Language (IDL) (Trademark of Research Systems, Inc.) on a Workstation/UNIX platform. The solution involves converting the application to a PC/Windows/RC platform, selected mainly by the availability of low cost, adaptable high-speed RC hardware. In order for the hybrid system to run, the IDL software was modified to account for platform differences. It was interesting to examine the gains and losses in performance on the new platform, as well as unexpected observations before implementing hardware. After substantial pre-hardware optimization steps, the necessity of hardware implementation for bottleneck code in the PC environment became evident and solvable beginning with the methodology described in [1], [2], and implementing a novel methodology for this specific application [6]. The PC-RC interface bandwidth problem for the class of applications with moderate input-output data rates but large intermediate multi-thread data streams has been addressed and mitigated. This opens a new class of satellite image processing applications for bottleneck problems solution using RC technologies. The issue of a science algorithm level of abstraction necessary for RC hardware implementation is also described. Selected Matlab functions already implemented in hardware were investigated for their direct applicability to the GOES-8 application with the intent to create a library of Matlab and IDL RC functions for ongoing work. A complete class of spacecraft image processing applications using embedded re-configurable computing technology to meet real-time requirements, including performance results and comparison with the existing system, is described in this paper.

Kizhner, Semion↗
NASA NTRS1989

Optimized orbits for the constellation of Space Station polar platforms

The orbital configuration of the Eos polar-platform constellation is examined to determine if baseline orbital parameters are appropriately specified to meet the mission task of measuring global oceanic mesoscale variability. Using the Nyquist sampling theorem, spatial and temporal measurement requirements are first established for the constellation. Based upon these requirements, the optimum solution indicates that a total of five spacecraft equipped with nadir-pointing altimeters, or two multibeam-equipped platforms, would be required to meet the mesoscale mapping task. Additional analyses were performed on both one- and and two-platform configurations as well as the complete four-platform Eos constellation. The results of these calculations show that the preferred scenario would be to equip all four Eos polar platforms with multibeam altimeters.

Chase, Robert↗
NASA NTRS2004

Understanding the Cray X1 System

This paper helps the reader understand the characteristics of the Cray X1 vector supercomputer system, and provides hints and information to enable the reader to port codes to the system. It provides a comparison between the basic performance of the X1 platform and other platforms that are available at NASA Ames Research Center. A set of codes, solving the Laplacian equation with different parallel paradigms, is used to understand some features of the X1 compiler. An example code from the NAS Parallel Benchmarks is used to demonstrate performance optimization on the X1 platform.

Cheung, Samson↗
NASA NTRS2002

Pre-Hardware Optimization of Spacecraft Image Processing Algorithms and Hardware Implementation

Spacecraft telemetry rates and telemetry product complexity have steadily increased over the last decade presenting a problem for real-time processing by ground facilities. This paper proposes a solution to a related problem for the Geostationary Operational Environmental Spacecraft (GOES-8) image data processing and color picture generation application. Although large super-computer facilities are the obvious heritage solution, they are very costly, making it imperative to seek a feasible alternative engineering solution at a fraction of the cost. The proposed solution is based on a Personal Computer (PC) platform and synergy of optimized software algorithms, and reconfigurable computing hardware (RC) technologies, such as Field Programmable Gate Arrays (FPGA) and Digital Signal Processors (DSP). It has been shown that this approach can provide superior inexpensive performance for a chosen application on the ground station or on-board a spacecraft.

Kizhner, Semion↗
NASA NTRS1991

Branch strategies - Modeling and optimization

The authors provide a common platform for modeling different schemes for reducing the branch-delay penalty in pipelined processors as well as evaluating the associated increased instruction bandwidth. Their objective is twofold: to develop a model for different approaches to the branch problem and to help select an optimal strategy after taking into account additional i-traffic generated by branch strategies. The model presented provides a flexible tool for comparing different branch strategies in terms of the reduction it offers in average branch delay and also in terms of the associated cost of wasted instruction fetches. This additional criterion turns out to be a valuable consideration in choosing between two strategies that perform almost equally. More importantly, it provides a better insight into the expected overall system performance. Simple compiler-support-based low-implementation-cost strategies can be very effective under certain conditions. An active branch prediction scheme based on loop buffers can be as competitive as a branch-target-buffer based strategy.

Dubey, Pradeep K.↗
NASA NTRS2002

Time-Dependent Simulations of Turbopump Flows

Unsteady flow simulations for RLV (Reusable Launch Vehicles) 2nd Generation baseline turbopump for one and half impeller rotations have been completed by using a 34.3 Million grid points model. MLP (Multi-Level Parallelism) shared memory parallelism has been implemented in INS3D, and benchmarked. Code optimization for cash based platforms will be completed by the end of September 2001. Moving boundary capability is obtained by using DCF module. Scripting capability from CAD (computer aided design) geometry to solution has been developed. Data compression is applied to reduce data size in post processing. Fluid/Structure coupling has been initiated.

Kiris, Cetin↗