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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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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Reducing V&V Cost of Flight Critical Systems: Myth or Reality?

This paper presents an overview of NASA research program on the V&V of flight critical systems. Five years ago, NASA started an effort to reduce the cost and possibly increase the effectiveness of V&V for flight critical systems. It is the right time to take a look back and realize what progress has been made. This paper describes our overall approach and the tools introduced to address different phases of the software lifecycle. For example, we have improved testing by developing a statistical learning approach tor defining test cases. The tool automatically identifies possible unsafe conditions by analyzing outliers in output data; using an iterative learning process, it can then generate more test cases that represent potentially unsafe regions of operation. At the code level, we have developed and made available as open source a static analyzer for C and C++ programs called IKOS. We have shown that IKOS is very precise in the analysis of embedded C programs (very few false positives) and a bit less for regular C and C++ code. At the design level, in collaboration with our NRA partners, we have developed a suite of analysis tools for Simulink models. The analysis is done in a compositional framework for scalability.

Brat, Guillaume P.↗
NASA NTRS2010

Converting a C-130 Hercules into a Compound Helicopter: A Conceptual Design Study

This study presents the performance and weight changes for a Compound C-130 as compared to the Baseline C-130H Hercules, using NDARC as the primary analysis tool. First, the C-130H was modeled within NDARC, from which performance at various conditions and a parametric weight statement were generated. Then, the C-130H NDARC file was modified to represent the Compound C-130, which was then put through the same performance analysis as the C-130H. A parametric weight statement was also calculated for the Compound C-130, which allowed for comparison to the C-130H. As part of the modeling of the Compound C-130, a Rotor Design Spreadsheet was created that would allow the direct calculation of the weight of the main rotors being added. Using composite materials led to considerable weight savings for both the rotor system and the hub weights. These weight savings are reflected in the NDARC Technology Factors which were determined to be 0.71 and 0.5 for the rotor blades and the hub/hinge system, respectively. Such Technology Factors suggest that using composites for other components could drastically lighten the Operating Empty Weight of the aircraft. The weight statements show the weights for each of the components on each aircraft. It is quite evident that the Compound C-130 has a higher Operating Empty Weight due to the addition of the two main rotors and a drive system to connect each engine group on the wing tips. Upon further analysis, the main weight driver is the drive system. While the main rotor/hub/hinge weight increase is to be expected, the weight increase due to the transmission drive and gear boxes are cause for concern. Unless a method can be found of reducing the weight of the drive system, the weight penalty makes the Compound a C-130 an inefficient aircraft in terms of payload/fuel capacity. Possible solutions are either off-loading some of the power requirements through the drive system or using composite materials in the construction of the drive system. The performance of the Compound C-130 versus the C-130H shows a clear need for more powerful engines than are currently present on the C-130H. This would also adversely affect the Operating Empty Weight since a larger power plant requires more weight. However, one advantage that the Compound C-130 presents is the ability to hover and operate at low speeds in Helicopter Mode. While the C-130H is unable to travel at speeds lower than its stall speed, the Compound C-130 is able to hover using the main rotors. Thus, the Compound C-130 is able to operate independent of runways, let alone the condition of the nearest runway. Ultimately, the Compound C-130 is an effective aircraft in theaters requiring VTOL aircraft due to geographical considerations in terms or performance. Unfortunately, the weight penalty associated with converting the C-130H to a Compound C-130 suggests that further work in the area of the drive systems is required.

Kottapalli, Anjaney P.↗
NASA NTRS1990

Space transfer concepts and analysis for exploration missions

The progress and results are summarized for mission/system requirements database; mission analysis; GN and C (Guidance, Navigation, and Control), aeroheating, Mars landing; radiation protection; aerobrake mass analysis; Shuttle-Z, TMIS (Trans-Mars Injection Stage); Long Duration Habitat Trade Study; evolutionary lunar and Mars options; NTR (Nuclear Thermal Rocket); NEP (Nuclear Electric Propulsion) update; SEP (Solar Electric Propulsion) update; orbital and space-based requirements; technology; piloted rover; programmatic task; and evolutionary and innovative architecture.

Source record↗
NASA NTRS1996

User's Manual for the Naval Interactive Data Analysis System-Climatologies (NIDAS-C), Version 2.0

This technical note provides the user's manual for the NIDAS-C system developed for the naval oceanographic office. NIDAS-C operates using numerous oceanographic data categories stored in an installed version of the Naval Environmental Operational Nowcast System (NEONS), a relational database management system (rdbms) which employs the ORACLE proprietary rdbms engine. Data management, configuration, and control functions for the supporting rdbms are performed externally. NIDAS-C stores and retrieves data to/from the rdbms but exercises no direct internal control over the rdbms or its configuration. Data is also ingested into the rdbms, for use by NIDAS-C, by external data acquisition processes. The data categories employed by NIDAS-C are as follows: Bathymetry - ocean depth at

USER M ANUALS↗
NASA NTRS2009

Flightspeed Integral Image Analysis Toolkit

The Flightspeed Integral Image Analysis Toolkit (FIIAT) is a C library that provides image analysis functions in a single, portable package. It provides basic low-level filtering, texture analysis, and subwindow descriptor for applications dealing with image interpretation and object recognition. Designed with spaceflight in mind, it addresses: Ease of integration (minimal external dependencies) Fast, real-time operation using integer arithmetic where possible (useful for platforms lacking a dedicated floatingpoint processor) Written entirely in C (easily modified) Mostly static memory allocation 8-bit image data The basic goal of the FIIAT library is to compute meaningful numerical descriptors for images or rectangular image regions. These n-vectors can then be used directly for novelty detection or pattern recognition, or as a feature space for higher-level pattern recognition tasks. The library provides routines for leveraging training data to derive descriptors that are most useful for a specific data set. Its runtime algorithms exploit a structure known as the "integral image." This is a caching method that permits fast summation of values within rectangular regions of an image. This integral frame facilitates a wide range of fast image-processing functions. This toolkit has applicability to a wide range of autonomous image analysis tasks in the space-flight domain, including novelty detection, object and scene classification, target detection for autonomous instrument placement, and science analysis of geomorphology. It makes real-time texture and pattern recognition possible for platforms with severe computational restraints. The software provides an order of magnitude speed increase over alternative software libraries currently in use by the research community. FIIAT can commercially support intelligent video cameras used in intelligent surveillance. It is also useful for object recognition by robots or other autonomous vehicles

Thompson, David R.↗
NASA NTRS1988

Overview of the Shuttle Imaging Radar (SIR-C)

The Shuttle Imaging Radar-C (SIR-C) experiment will provide increased capability over Seasat and the two previous Shuttle Imaging Radars by acquiring digital images simultaneously at two microwave frequencies (L- and C-band) with multiple signal polarizations (HH, VV, HV, VH). The SIR-C is a dual bandwidth system so that investigators can choose a high or low resolution mode (20 and 10 MHz, respectively). An X-band SAR with VV polarization will be flown with SIR-C, resulting in a three-frequency capability. The SIR-C prototype data will be acquired using an airborne imaging radar to test designs that will be implemented on SIR-C, to develop the overall calibration strategy for SIR-C, and to develop data analysis tools for SIR-C data.

Evans, D.↗
NASA NTRS1989

Preliminary design of the Shuttle-C avionics recovery system

The analysis done in developing a recovery system for the Shuttle-C cargo vehicle is presented. This recovery system is comprised of a reentry capsule which houses the vehicles avionics. The avionics are contained in a single package which is extracted from the capsule by the parachute recovery system. The Shuttle-C will be able to satisfy NASA's design and mission requirements. Included, is an analysis of the structural, thermal protection, and parachute recovery systems. A discussion of the merits of the proposed system is also included.

Brookfield, Morgan↗