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At least 721 records · Page 40

Parabolic aircraft solidification experiments

A number of solidification experiments have been utilized throughout the Materials Processing in Space Program to provide an experimental environment which minimizes variables in solidification experiments. Two techniques of interest are directional solidification and isothermal casting. Because of the wide-spread use of these experimental techniques in space-based research, several MSAD experiments have been manifested for space flight. In addition to the microstructural analysis for interpretation of the experimental results from previous work with parabolic flights, it has become apparent that a better understanding of the phenomena occurring during solidification can be better understood if direct visualization of the solidification interface were possible. Our university has performed in several experimental studies such as this in recent years. The most recent was in visualizing the effect of convective flow phenomena on the KC-135 and prior to that were several successive contracts to perform directional solidification and isothermal casting experiments on the KC-135. Included in this work was the modification and utilization of the Convective Flow Analyzer (CFA), the Aircraft Isothermal Casting Furnace (ICF), and the Three-Zone Directional Solidification Furnace. These studies have contributed heavily to the mission of the Microgravity Science and Applications' Materials Science Program.

Workman, Gary L.↗

Glenn Heat Transfer Simulation and Solver Graphical User Interface: Development and Testing

In the Tui ine Branch of the Turbomachinery and Propulsion Systems Division, researching and developing efficient turbine aerothermodynamics technologies is the main objective. Creating effective turbines for jet engines is a process which, if based purely on physical experimental testing, would be extremely expensive. It is for this reason, and also for the reasons of speed and ease, that the Turbine Branch spends a large amount of effort working with simulations of turbines. Specifically, they focus their work on two main fields: Computational Field Dynamics (CFD), and Experimental data analysis. The experimental field involves comparing experimental results to simulated results, whereas the CFD field involves running these simulations. The simulations are applied to aerodynamics and heat transfer cases, for both steady and unsteady flow conditions. By and large this work is applied to the domain of flow and heat transfer in axial turbines. The main application used to run these heat flow simulations is GlennHT. This program, recently rewritten in FORTRAN 90, allows the user to input a job file which specifies all the necessary parameters needed to simulate flow through a user-defined grid. There are several other executables used as well, ranging in application from converting grid files to and from particular formats, to merging blocks in a connectivity file, to converting connectivity files to a GlennHT compatible format. All of these executables are run from the command line in a terminal; some of them have interactive prompts where the user must specify the files to be manipulated after the program starts, while others take all of their parameters from the command line. With this amount of variation comes a good deal of commands and formats to memorize, which can cause slower and less efficient work, as users may forget how to execute a certain program, or not remember the pathnames of the files they wish to use. Two years ago, steps were made to expedite this process with a graphical user interface (GUI) that combines the functionality of all the executables along with adding some new functionality, such as residuals graphing and boundary conditions creation. Upon my beginning here at Glenn, many parts of the GUI, which was developed in Java, were nonfunctional. There were also issues with cross-platforming, as systems in the branch were transitioning from Silicon Graphics (SGI) machines to Linux machines. My goals this summer are to finish the parts of the GUI that are not yet completed, fix parts that did not work correctly, expand the functionality to include other useful features, such as grid surface highlighting, and make the system compatible with both Linux and SGI. I will also be heavily testing the system and providing sufficient documentation on how to use the GUI, as no such documentation existed previously.

Kardamis, Joseph R.↗

3D Structured Grid Generation Codes for Turbomachinery

This report describes the research tasks during the past year. The research was mainly in the area of computational grid generation in support of CFD analyses of turbomachinery components. In addition to the grid generation work, a numerical simulation was obtained for the flow through a centrifugal gas compressor using an unstructured Navier-Stokes solver. Other tasks involved many different turbomachinery component analyses. These analyses were performed for NASA projects or for industrial applications. The work includes both centrifugal and axial machines, single and multiple blade rows, and steady and unsteady analyses. Over the past five years, a set of structured grid generation codes were developed that allow grids to be obtained fairly quickly for the large majority of configurations we encounter. These codes do not comprise a generalized grid generation package; they are noninteractive codes specifically designed for turbomachinery blade row geometries. But because of this limited scope, the codes are small, fast, and portable, and they can be run in the batch mode on small workstations. During the past year, these programs were used to generate computational grids were modified for a wide variety of configurations. In particular, the codes or wrote supplementary codes to improve our grid generation capabilities for multiple blade row configurations. This involves generating separate grids for each blade row, and then making them match and overlap by a few grid points at their common interface so that fluid properties are communicated across the interface. Unsteady rotor/stator analyses were performed for an axial turbine, a centrifugal compressor, and a centrifugal pump. Steady-state single-blade-row analyses were made for a study of blade sweep in transonic compressors. There was also cooperation on the application of an unstructured Navier-Stokes solver for turbomachinery flow simulations. In particular, the unstructured solver was used to analyze the flow through a centriftio compressor impeller.

Loellbach, James↗

Engineering and Scientific Applications: Using MatLab(Registered Trademark) for Data Processing and Visualization

MatLab(R) (MATrix LABoratory) is a numerical computation and simulation tool that is used by thousands Scientists and Engineers in many cou ntries. MatLab does purely numerical calculations, which can be used as a glorified calculator or interpreter programming language; its re al strength is in matrix manipulations. Computer algebra functionalities are achieved within the MatLab environment using "symbolic" toolbo x. This feature is similar to computer algebra programs, provided by Maple or Mathematica to calculate with mathematical equations using s ymbolic operations. MatLab in its interpreter programming language fo rm (command interface) is similar with well known programming languag es such as C/C++, support data structures and cell arrays to define c lasses in object oriented programming. As such, MatLab is equipped with most ofthe essential constructs of a higher programming language. M atLab is packaged with an editor and debugging functionality useful t o perform analysis of large MatLab programs and find errors. We belie ve there are many ways to approach real-world problems; prescribed methods to ensure foregoing solutions are incorporated in design and ana lysis of data processing and visualization can benefit engineers and scientist in gaining wider insight in actual implementation of their perspective experiments. This presentation will focus on data processing and visualizations aspects of engineering and scientific applicati ons. Specifically, it will discuss methods and techniques to perform intermediate-level data processing covering engineering and scientifi c problems. MatLab programming techniques including reading various data files formats to produce customized publication-quality graphics, importing engineering and/or scientific data, organizing data in tabu lar format, exporting data to be used by other software programs such as Microsoft Excel, data presentation and visualization will be discussed. The presentation will emphasize creating practIcal scripts (pro grams) that extend the basic features of MatLab TOPICS mclude (1) Ma trix and vector analysis and manipulations (2) Mathematical functions (3) Symbolic calculations & functions (4) Import/export data files (5) Program lOgic and flow control (6) Writing function and passing parameters (7) Test application programs

Sen, Syamal K.↗

OptiMX

OptiMX is a GUI-oriented program with principal aim to be an easy to use, yet comprehensive, interactive accelerator optics design and analysis tool. It was originally developed starting in the 1990s as an MS Windows centric application using the commercial Borland OWL framework. In the spring of 2014, a decision was made to port OptiM to Qt, a modern, portable and open framework. As much as possible, the original interface was preserved.While a significant amount of refactoring was required, the underlying physics has been for the most, left unchanged. The custom plots of the original application have been replaced with functional equivalents based on a stable and well-established library (qwt). With very few minor exceptions the new refactored OptiMX should be a drop-in replacement for the original OWL version.

Lebedev, ValeriA. [Joint Inst. for Nuclear Researc↗

Mechanisms of active control in cylindrical fuselage structures

This paper summarizes ongoing efforts to understand and exploit active control techniques for low frequency noise suppression in aerospace applications. Analytical models are utilized in an effort to understand the mechanisms that govern noise transmission into acoustic spaces enclosed by lightweight structures and to examine the results of experimental implementations of active control schemes. Emphasis is placed on attaining global noise reductions using a minimum number of actuators rather than localized control over many subregions. This program has demonstrated the effect of synchrophasing and interface modal filtering, in limiting the modal density within the acoustic space, and how strong reactive effects may occur in two dimensional geometries. Finally, the performance of active control systems utilizing acoustic and vibration actuators is evaluated. Suppressions of 10 to 30 dB are demonstrated in practice, and performance is discussed in relation to the physical mechanisms and parameters of the system.

Silcox, R. J.↗

The Application of Modeling and Simulation to the Behavioral Deficit of Autism

This abstract describes a research effort to apply technological advances in virtual reality simulation and computer-based games to create behavioral modification programs for individuals with Autism Spectrum Disorder (ASD). The research investigates virtual social skills training within a 3D game environment to diminish the impact of ASD social impairments and to increase learning capacity for optimal intellectual capability. Individuals with autism will encounter prototypical social contexts via computer interface and will interact with 3D avatars with predefined roles within a game-like environment. Incremental learning objectives will combine to form a collaborative social environment. A secondary goal of the effort is to begin the research and development of virtual reality exercises aimed at triggering the release of neurotransmitters to promote critical aspects of synaptic maturation at an early age to change the course of the disease.

Anton, John J.↗

Programmable Digital Controller

An existing three-channel analog servo loop controller has been redesigned for piezoelectric-transducer-based (PZT-based) etalon control applications to a digital servo loop controller. This change offers several improvements over the previous analog controller, including software control over proportional-integral-derivative (PID) parameters, inclusion of other data of interest such as temperature and pressure in the control laws, improved ability to compensate for PZT hysteresis and mechanical mount fluctuations, ability to provide pre-programmed scanning and stepping routines, improved user interface, expanded data acquisition, and reduced size, weight, and power.

Wassick, Gregory J.↗

Liquid/vapour phase separation in He-4 using electric fields

In space, a replacement must be found for gravity to physically control and, in certain instances, contain cryogenic liquids. A program has been started at the Jet Propulsion Laboratory to study the use of electric field generated forces to establish the required orienting effects. Measurements which show that it is possible to apply strong enough electric fields to a liquid/vapor interface of He-4 to obtain an orienting force comparable to gravity are presented. Our measurements span the temperature range 1.7-4.2 K and demonstrate the applicability of Pashen's law for maximum attainable field before breakdown occurs. Some advantages of the electric field separator as opposed to passive surface tension devices are identified.

Israelsson, U. E.↗

Tool for Statistical Analysis and Display of Landing Sites

MarsLS is a software tool for analyzing statistical dispersion of spacecraft-landing sites and displaying the results of its analyses. Originally intended for the Mars Explorer Rover (MER) mission, MarsLS is also applicable to landing sites on Earth and non-MER sites on Mars. MarsLS is a collection of interdependent MATLAB scripts that utilize the MATLAB graphical-user-interface software environment to display landing-site data (see figure) on calibrated image-maps of the Martian or other terrain. The landing-site data comprise latitude/longitude pairs generated by Monte Carlo runs of other computer programs that simulate entry, descent, and landing. Using these data, MarsLS can compute a landing-site ellipse a standard means of depicting the area within which the spacecraft can be expected to land with a given probability. MarsLS incorporates several features for the user s convenience, including capabilities for drawing lines and ellipses, overlaying kilometer or latitude/longitude grids, drawing and/or specifying lines and/or points, entering notes, defining and/or displaying polygons to indicate hazards or areas of interest, and evaluating hazardous and/or scientifically interesting areas. As part of such an evaluation, MarsLS can compute the probability of landing in a specified polygonal area.

Wawrzyniak, Geoffrey↗

Java Programming Language

The Java seminar covers the fundamentals of Java programming language. No prior programming experience is required for participation in the seminar. The first part of the seminar covers introductory concepts in Java programming including data types (integer, character, ..), operators, functions and constants, casts, input, output, control flow, scope, conditional statements, and arrays. Furthermore, introduction to Object-Oriented programming in Java, relationships between classes, using packages, constructors, private data and methods, final instance fields, static fields and methods, and overloading are explained. The second part of the seminar covers extending classes, inheritance hierarchies, polymorphism, dynamic binding, abstract classes, protected access. The seminar conclude by introducing interfaces, properties of interfaces, interfaces and abstract classes, interfaces and cailbacks, basics of event handling, user interface components with swing, applet basics, converting applications to applets, the applet HTML tags and attributes, exceptions and debugging.

Shaykhian, Gholam Ali↗

Fiber Optic Experience with the Smart Actuation System on the F-18 Systems Research Aircraft

High bandwidth, immunity to electromagnetic interference, and potential weight savings have led to the development of fiber optic technology for future aerospace vehicle systems. This technology has been incorporated in a new smart actuator as the primary communication interface. The use of fiber optics simplified system integration and significantly reduced wire count. Flight test results showed that fiber optics could be used in aircraft systems and identified critical areas of development of fly-by-light technology. This paper documents the fiber optic experience gained as a result of this program, and identifies general design considerations that could be used in a variety of specific applications of fiber optic technology. Environmental sensitivities of fiber optic system components that significantly contribute to optical power variation are discussed. Although a calibration procedure successfully minimized the effect of fiber optic sensitivities, more standardized calibration methods are needed to ensure system operation and reliability in future aerospace vehicle systems.

Zavala, Eddie↗

Real-Time Payload Control and Monitoring on the World Wide Web

World Wide Web (W3) technologies such as the Hypertext Transfer Protocol (HTTP) and the Java object-oriented programming environment offer a powerful, yet relatively inexpensive, framework for distributed application software development. This paper describes the design of a real-time payload control and monitoring system that was developed with W3 technologies at NASA Ames Research Center. Based on Java Development Toolkit (JDK) 1.1, the system uses an event-driven "publish and subscribe" approach to inter-process communication and graphical user-interface construction. A C Language Integrated Production System (CLIPS) compatible inference engine provides the back-end intelligent data processing capability, while Oracle Relational Database Management System (RDBMS) provides the data management function. Preliminary evaluation shows acceptable performance for some classes of payloads, with Java's portability and multimedia support identified as the most significant benefit.

Sun, Charles↗

The development of a program analysis environment for Ada: Reverse engineering tools for Ada

The Graphical Representations of Algorithms, Structures, and Processes for Ada (GRASP/Ada) has successfully created and prototyped a new algorithm level graphical representation for Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and thus improve reliability and reduce costs. The emphasis was on the automatic generation of the CSD from Ada source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada source code. In Phase 1 of the GRASP/Ada project, the CSD graphical constructs were created and applied manually to several small Ada programs. A prototype (Version 1) was designed and implemented using FLEX and BISON running under the Virtual Memory System (VMS) on a VAX 11-780. In Phase 2, the prototype was improved and ported to the Sun 4 platform under UNIX. A user interface was designed and partially implemented. The prototype was applied successfully to numerous Ada programs ranging in size from several hundred to several thousand lines of source code. In Phase 3 of the project, the prototype was prepared for limited distribution (GRASP/Ada Version 3.0) to facilitate evaluation. The user interface was extensively reworked. The current prototype provides the capability for the user to generate CSD from Ada source code in a reverse engineering mode with a level of flexibility suitable for practical application.

Cross, James H., II↗

Parabolic Flight Investigation for Advanced Exercise Concept Hardware Hybrid Ultimate Lifting Kit (HULK)

Long-duration space flight poses many hazards to the health of the crew. Among those hazards is the physiological deconditioning of the musculoskeletal and cardiovascular systems due to prolonged exposure to microgravity. To combat this erosion of physical condition space flight may take on the crew, the Human Research Program (HRP) is charged with developing Advanced Exercise Concepts to maintain astronaut health and fitness during long-term missions, while keeping device mass, power, and volume to a minimum. The goal of this effort is to preserve the physical capability of the crew to perform mission critical tasks in transit and during planetary surface operations. The HULK is a pneumatic-based exercise system, which provides both resistive and aerobic modes to protect against human deconditioning in microgravity. Its design targeted the International Space Station (ISS) Advanced Resistive Exercise Device (ARED) high level performance characteristics and provides up to 600 foot pounds resitive loading with the capability to allow for eccentric to concentric (E:C) ratios of higher than 1:1 through a DC motor assist component. The device's rowing mode allows for high cadence aerobic activity. The HULK parabolic flight campaign, conducted through the NASA Flight Opportunities Program at Ellington Field, resulted in the creation of device specific data sets including low fidelity motion capture, accelerometry and both inline and ground reaction forces. These data provide a critical link in understanding how to vibration isolate the device in both ISS and space transit applications. Secondarily, the study of human exercise and associated body kinematics in microgravity allows for more complete understanding of human to machine interface designs to allow for maximum functionality of the device in microgravity.

countermeasures↗

Programmable Phase Selection between Altermagnetic and Noncentrosymmetric Polymorphs of MnTe on InP via Molecular Beam Epitaxy

Phase selecting nearly degenerate crystalline polymorphs during epitaxial growth can be challenging yet critical to targeting physical properties for specific applications. Here, we establish how phase selectivity of altermagnetic and noncentrosymmetric polymorphs of MnTe can be programmed by subtle changes to the surface of lattice-matched InP substrates in molecular beam epitaxy growth. Bulk altermagnetic MnTe is thermodynamically stable in the hexagonal NiAs-structure and is synthesized here on the polar (111)A surface (In-terminated) of InP, while the noncentrosymmetric, cubic ZnS-structure with wide band gap (>3 eV), which epitaxially matches III–V materials, is stabilized on the (111)B surface (P-terminated). Electron microscopy, X-ray photoemission spectroscopy, and reflection high-energy electron diffraction indicate that phase selection is triggered at the interface and proceeds along the growing surface. First-principles calculations suggest that interfacial termination and strain have a significant effect on the interfacial energy; stabilizing the NiAs polymorph on the In-terminated surface and the ZnS structure on the P-terminated surface. Here, selectively grown, high-quality, phase pure films of both MnTe polymorphs will enable our understanding of the novel properties of these materials, thereby facilitating their use in new applications ranging from spintronics to microelectronic devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Ground Operations Aerospace Language (GOAL). Volume 3: Data bank

The GOAL (Ground Operations Aerospace Language) test programming language was developed for use in ground checkout operations in a space vehicle launch environment. To insure compatibility with a maximum number of applications, a systematic and error-free method of referencing command/response (analog and digital) hardware measurements is a principle feature of the language. Central to the concept of requiring the test language to be independent of launch complex equipment and terminology is that of addressing measurements via symbolic names that have meaning directly in the hardware units being tested. To form the link from test program through test system interfaces to the units being tested the concept of a data bank has been introduced. The data bank is actually a large cross-reference table that provides pertinent hardware data such as interface unit addresses, data bus routings, or any other system values required to locate and access measurements.

Source record↗

A simple element for multilayer beams in NASTRAN thermal stress analysis

In the application of NASTRAN, structural members are usually represented by bar elements with multipoint constraint cards to enforce the interface conditions. While this is a very powerful method in principle, it was found that in practice the process for specification of constraints became tedious and error prone, unless the geometry was simple and the number of grid points low. An alternative approach was found within the framework of the NASTRAN program. This approach made use of the idea that a thermal distortion in a multilayer beam may be similar to a homogeneous beam with a thermal gradient across the cross section. The exact mathematical derivation for the equivalent beam, and all the necessary formulae for the equivalent parameters in NASTRAN analysis are presented. Some numerical examples illustrate the simplicity and ease of this approach for finite element analysis.

Chen, W. T.↗