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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 289 records · Page 16
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NASA NTRS2000

Model Checking JAVA Programs Using Java Pathfinder

This paper describes a translator called JAVA PATHFINDER from JAVA to PROMELA, the "programming language" of the SPIN model checker. The purpose is to establish a framework for verification and debugging of JAVA programs based on model checking. This work should be seen in a broader attempt to make formal methods applicable "in the loop" of programming within NASA's areas such as space, aviation, and robotics. Our main goal is to create automated formal methods such that programmers themselves can apply these in their daily work (in the loop) without the need for specialists to manually reformulate a program into a different notation in order to analyze the program. This work is a continuation of an effort to formally verify, using SPIN, a multi-threaded operating system programmed in Lisp for the Deep-Space 1 spacecraft, and of previous work in applying existing model checkers and theorem provers to real applications.

Havelund, Klaus↗
NASA NTRS2003

Requirements Development for the NASA Advanced Engineering Environment (AEE)

The requirements development process for the Advanced Engineering Environment (AEE) is presented. This environment has been developed to allow NASA to perform independent analysis and design of space transportation architectures and technologies. Given the highly collaborative and distributed nature of AEE, a variety of organizations are involved in the development, operations and management of the system. Furthermore, there are additional organizations involved representing external customers and stakeholders. Thorough coordination and effective communication is essential to translate desired expectations of the system into requirements. Functional, verifiable requirements for this (and indeed any) system are necessary to fulfill several roles. Requirements serve as a contractual tool, configuration management tool, and as an engineering tool, sometimes simultaneously. The role of requirements as an engineering tool is particularly important because a stable set of requirements for a system provides a common framework of system scope and characterization among team members. Furthermore, the requirements provide the basis for checking completion of system elements and form the basis for system verification. Requirements are at the core of systems engineering. The AEE Project has undertaken a thorough process to translate the desires and expectations of external customers and stakeholders into functional system-level requirements that are captured with sufficient rigor to allow development planning, resource allocation and system-level design, development, implementation and verification. These requirements are maintained in an integrated, relational database that provides traceability to governing Program requirements and also to verification methods and subsystem-level requirements.

Rogers, Eric↗
NASA NTRS1991

Experimental verification of a new laminar airfoil: A project for the graduate program in aeronautics

Two reports on student activities to determine the properties of a new laminar airfoil which were delivered at a conference on soaring technology are presented. The papers discuss a wind tunnel investigation and analysis of the SM701 airfoil and verification of the SM701 airfoil aerodynamic charcteristics utilizing theoretical techniques. The papers are based on a combination of analytical design, hands-on model fabrication, wind tunnel calibration and testing, data acquisition and analysis, and comparison of test results and theory.

Nicks, Oran W.↗
NASA NTRS2004

Jet Noise Reduction

The Acoustics Branch is responsible for reducing noise levels for jet and fan components on aircraft engines. To do this, data must be measured and calibrated accurately to ensure validity of test results. This noise reduction is accomplished by modifications to hardware such as jet nozzles, and by the use of other experimental hardware such as fluidic chevrons, elliptic cores, and fluidic shields. To insure validity of data calibration, a variety of software is used. This software adjusts the sound amplitude and frequency to be consistent with data taken on another day. Both the software and the hardware help make noise reduction possible. work properly. These software programs were designed to make corrections for atmosphere, shear, attenuation, electronic, and background noise. All data can be converted to a one-foot lossless condition, using the proper software corrections, making a reading independent of weather and distance. Also, data can be transformed from model scale to full scale for noise predictions of a real flight. Other programs included calculations of Over All Sound Pressure Level (OASPL), Effective Perceived Noise Level (EPNL). OASPL is the integration of sound with respect to frequency, and EPNL is weighted for a human s response to different sound frequencies and integrated with respect to time. With the proper software correction, data taken in the NATR are useful in determining ways to reduce noise. display any difference between two or more data files. Using this program and graphs of the data, the actual and predicted data can be compared. This software was tested on data collected at the Aero Acoustic Propulsion Laboratory (AAPL) using a variety of window types and overlaps. Similarly, short scripts were written to test each individual program in the software suite for verification. Each graph displays both the original points and the adjusted points connected with lines. During this summer, data points were taken during a live experiment at the AAPL to measure Nozzle Acoustic Test Rig (NATR) background noise levels. Six condenser microphones were placed in strategic locations around the dome and the inlet tunnel to measure different noise sources. From the control room the jet was monitored with the help of video cameras and other sensors. The data points were recorded, reduced, and plotted, and will be used to plan future modifications to the NATR. The primary goal to create data reduction test programs and provide verification was completed. As a result of the internship, I learned C/C++, UNIX/LINUX, Excel, and acoustic data processing methods. I also recorded data at the AAPL, then processed and plotted it. These data would be useful to compare against existing data. In addition, I adjusted software to work on the Mac OSX platform. And I used the available training resources.

Kenny, Patrick↗
NASA NTRS2007

Revisiting Training and Verification Process Implementation for Risk Reduction on New Missions at NASA Jet Propulsion Laboratory

In 2003 we proposed an effort to develop a core program of standardized training and verification practices and standards against which the implementation of these practices could be measured. The purpose was to provide another means of risk reduction for deep space missions to preclude the likelihood of a repeat of the tragedies of the 1998 Mars missions. We identified six areas where the application of standards and standardization would benefit the overall readiness process for flight projects at JPL. These are Individual Training, Team Training, Interface and Procedure Development, Personnel Certification, Interface and procedure Verification, and Operations Readiness Testing. In this paper we will discuss the progress that has been made in the tasks of developing the proposed infrastructure in each of these areas. Specifically we will address the Position Training and Certification Standards that are now available for each operational position found on our Flight Operations Teams (FOT). We will also discuss the MGSS Baseline Flight Operations Team Training Plan which can be tailored for each new flight project at JPL. As these tasks have been progressing, the climate and emphasis for Training and for V and V at JPL has changed, and we have learned about the expansion, growth, and limitations in the roles of traditional positions at JPL such as the Project's Training Engineer, V and V Engineer, and Operations Engineer. The need to keep a tight rein on budgets has led to a merging and/or reduction in these positions which pose challenges to individual capacities and capabilities. We examine the evolution of these processes and the roles involved while taking a look at the impact or potential impact of our proposed training related infrastructure tasks. As we conclude our examination of the changes taking place for new flight projects, we see that the importance of proceeding with our proposed tasks and adapting them to the changing climate remains an important element in reducing the risk in the challenging business of space exploration.

verifications↗
NASA NTRS1971

Digital autopilots: Design considerations and simulator evaluations

The development of a digital autopilot program for a transport aircraft and the evaluation of that system's performance on a transport aircraft simulator is discussed. The digital autopilot includes three axis attitude stabilization, automatic throttle control and flight path guidance functions with emphasis on the mode progression from descent into the terminal area through automatic landing. The study effort involved a sequence of tasks starting with the definition of detailed system block diagrams of control laws followed by a flow charting and programming phase and concluding with performance verification using the transport aircraft simulation. The autopilot control laws were programmed in FORTRAN 4 in order to isolate the design process from requirements peculiar to an individual computer.

Osder, S.↗
NASA NTRS1991

PISCES: A Tool for Predicting Software Testability

Before a program can fail, a software fault must be executed, that execution must alter the data state, and the incorrect data state must propagate to a state that results directly in an incorrect output. This paper describes a tool called PISCES (developed by Reliable Software Technologies Corporation) for predicting the probability that faults in a particular program location will accomplish all three of these steps causing program failure. PISCES is a tool that is used during software verification and validation to predict a program's testability.

Voas, Jeffrey M.↗
NASA NTRS2021

Europa Clipper Payload Verification and Validation: Early Architecture and Implementation

NASA’s Europa Clipper mission will investigate the Jovian icy moon Europa with a sophisticated payload consisting of a suite of nine instruments. Clipper’s observations will help provide answers to a broad range of scientific objectives related to Europa’s habitability. As the project proceeds through Phase C, we are building confidence in the system’s ability to achieve these science goals by implementing a rigorous payload verification and validation (V&V) program. This paper details the planned structure and implementation of the Europa Clipper payload V&V program as it exists leading up to the project critical design review (CDR), before the bulk of instrument- or payload- level V&V activities have begun. We first explain the context for payload V&V on Europa Clipper, including its interfaces with other parts of the project system. We then describe the taxonomy of V&V concepts and their interrelationships, followed by a discussion on how this framework allows us to codify interfaces, processes, and ideas that are key to a successful V&V program. We focus on key aspects of the planning phases of V&V, especially establishing a complete set of verification items and accurately mapping them into appropriate verification activities. The second half of the paper describes the logistics of implementing this framework onto our actual payload system, including the processes and tools we use to manage and communicate agreements, changes, and risks across the project. We conclude with a reflection on the unique drivers and challenges of the V&V program concept development so far and the work that is planned for phase D implementation.

Srivastava, Priyanka↗
NASA NTRS1989

Precision segmented reflector, figure verification sensor

The Precision Segmented Reflector (PSR) program currently under way at the Jet Propulsion Laboratory is a test bed and technology demonstration program designed to develop and study the structural and material technologies required for lightweight, precision segmented reflectors. A Figure Verification Sensor (FVS) which is designed to monitor the active control system of the segments is described, a best fit surface is defined, and an image or wavefront quality of the assembled array of reflecting panels is assessed

Manhart, Paul K.↗
NASA NTRS1989

Coolant side heat transfer with rotation. Task 3 report: Application of computational fluid dynamics

An experimental and analytical program was conducted to investigate heat transfer and pressure losses in rotating multipass passages with configurations and dimensions typical of modern turbine blades. The objective of this program is the development and verification of improved analysis methods that will form the basis for a design system that will produce turbine components with improved durability. As part of this overall program, a technique is developed for computational fluid dynamics. The specific objectives were to: select a baseline CFD computer code, assess the limitations of the baseline code, modify the baseline code for rotational effects, verify the modified code against benchmark experiments in the literature, and to identify shortcomings in the code as revealed by the verification. The Pratt and Whitney 3D-TEACH CFD code was selected as the vehicle for this program. The code was modified to account for rotating internal flows, and these modifications were evaluated for flow characteristics of those expected in the application. Results can make a useful contribution to blade internal cooling.

Kopper, F. C.↗
NASA NTRS2007

Modeling of Compressible Flow with Friction and Heat Transfer Using the Generalized Fluid System Simulation Program (GFSSP)

The present paper describes the verification and validation of a quasi one-dimensional pressure based finite volume algorithm, implemented in Generalized Fluid System Simulation Program (GFSSP), for predicting compressible flow with friction, heat transfer and area change. The numerical predictions were compared with two classical solutions of compressible flow, i.e. Fanno and Rayleigh flow. Fanno flow provides an analytical solution of compressible flow in a long slender pipe where incoming subsonic flow can be choked due to friction. On the other hand, Raleigh flow provides analytical solution of frictionless compressible flow with heat transfer where incoming subsonic flow can be choked at the outlet boundary with heat addition to the control volume. Nonuniform grid distribution improves the accuracy of numerical prediction. A benchmark numerical solution of compressible flow in a converging-diverging nozzle with friction and heat transfer has been developed to verify GFSSP's numerical predictions. The numerical predictions compare favorably in all cases.

Bandyopadhyay, Alak↗
NASA NTRS1974

An integral equation formulation for predicting radiation patterns of a space shuttle annular slot antenna

An integral equation formulation is applied to predict pitch- and roll-plane radiation patterns of a thin VHF/UHF (very high frequency/ultra high frequency) annular slot communications antenna operating at several locations in the nose region of the space shuttle orbiter. Digital computer programs used to compute radiation patterns are given and the use of the programs is illustrated. Experimental verification of computed patterns is given from measurements made on 1/35-scale models of the orbiter.

Jones, J. E.↗
NASA NTRS1976

Timeline Analysis Program (TLA-1)

The Timeline Analysis Program (TLA-1) was described. This program is a crew workload analysis computer program that was developed and expanded from previous workload analysis programs, and is designed to be used on the NASA terminal controlled vehicle program. The following information is described: derivation of the input data, processing of the data, and form of the output data. Eight scenarios that were created, programmed, and analyzed as verification of this model were also described.

Miller, K. H.↗
NASA NTRS1973

On a basic model of circulatory, fluid, and electrolyte regulation in the human system based upon the model of Guyton

A detailed description of Guyton's model and modifications are provided. Also included are descriptions of several typical experiments which the model can simulate to illustrate the model's general utility. A discussion of the problems associated with the interfacing of the model to other models such as respiratory and thermal regulation models which is prime importance since these stimuli are not present in the current model is also included. A user's guide for the operation of the model on the Xerox Sigma 3 computer is provided and two programs are described. A verification plan and procedure for performing experiments is also presented.

White, R. J.↗
NASA NTRS1979

Hydrogen chloride partitioning in a Titan III exhaust cloud diluted with ambient air

Measurements and analysis are presented of the partitioning of HCl between hydrochloric acid aerosol and gaseous HCl in a Titan III exhaust cloud, as the cloud is diluted with humid ambient air. Partitioning was determined by measuring the gaseous HCl concentration with a recently developed airborne Gas Filter Correlation detector and simultaneously with a chemiluminescence detector which measures total HCl. Although equilibrium predictions for HCl aerosol formation indicated that no HCl aerosol should exist in the exhaust cloud for the meteorological conditions of this launch, the measurements indicated significant HCl aerosol formation. These measurements will provide verification for advanced modeling programs now under development.

Sebacher, D. I.↗
NASA NTRS1982

The astronomical data base and retrieval system at NASA

More than 250 machine-readable catalogs of stars and extended celestial objects are now available at the NASA/Goddard Space Flight Center (GSFC) as the result of over a decade of catalog acquisition, verification and documentation. Retrieval programs are described which permit the user to obtain from a remote terminal bibliographical listings for stars; to find all celestial objects from a given list that are within a defined angular separation from each object in another list; to plot celestial objects on overlays for sky survey plate areas; and to search selected catalogs for objects by criteria of position, identification number, magnitude or spectral type.

Mead, J. M.↗
NASA NTRS1987

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

Clarke, Clifton A.↗