Search NASA⌕ Search

SEARCH · Search NASA

Results for “Load sharing”

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 271 records · Page 15

Cold Survivable Distributed Motor Controller (CSDMC)

This paper presents the results of NASA’s COLDTECH development entitled “Cold Survivable Distributed Motor Controller (CSDMC)”. This work addresses the need to lower the mass, power and volume of the motor control electronics and its associated cabling. Landed payload mass of ocean world missions typically requires a spacecraft launch mass of 7-10x the landed mass due to the required propellant to get the payload to the surface. Reduction of landed mass leads to cheaper, more frequent missions and/or increased science return. This work addresses this need by developing a distributed electronics architecture, which places control and power electronics near or at actuators and instruments. The outcome of this effort will result in a 10X reduction in harness mass, enabling a significant increase in science payload which then enables more capable sample acquisition, delivery and analysis systems on these missions. Placing the control and power conversion electronics at or near the actuators or instruments is the cornerstone of our distributed architecture. To do this, we developed the technology necessary to distribute the electronics and place them on a shared interface and power bus. This enables a significant reduction in cable mass along with its associated complexity. This allows spacecraft designers to take advantage of volume at the extremities that would normally not be utilized. In this paper we discuss the technologies and system design to achieve these goals in support of ocean world missions. These technologies include the development of our motor control modules, a point of load regulator and isolated converter modules along with the packaging technology necessary to allow our electronics to survive the extreme temperatures.

Stell, Chris↗

FAST User Guide

The Flow Analysis Software Toolkit, FAST, is a software environment for visualizing data. FAST is a collection of separate programs (modules) that run simultaneously and allow the user to examine the results of numerical and experimental simulations. The user can load data files, perform calculations on the data, visualize the results of these calculations, construct scenes of 3D graphical objects, and plot, animate and record the scenes. Computational Fluid Dynamics (CFD) visualization is the primary intended use of FAST, but FAST can also assist in the analysis of other types of data. FAST combines the capabilities of such programs as PLOT3D, RIP, SURF, and GAS into one environment with modules that share data. Sharing data between modules eliminates the drudgery of transferring data between programs. All the modules in the FAST environment have a consistent, highly interactive graphical user interface. Most commands are entered by pointing and'clicking. The modular construction of FAST makes it flexible and extensible. The environment can be custom configured and new modules can be developed and added as needed. The following modules have been developed for FAST: VIEWER, FILE IO, CALCULATOR, SURFER, TOPOLOGY, PLOTTER, TITLER, TRACER, ARCGRAPH, GQ, SURFERU, SHOTET, and ISOLEVU. A utility is also included to make the inclusion of user defined modules in the FAST environment easy. The VIEWER module is the central control for the FAST environment. From VIEWER, the user can-change object attributes, interactively position objects in three-dimensional space, define and save scenes, create animations, spawn new FAST modules, add additional view windows, and save and execute command scripts. The FAST User Guide uses text and FAST MAPS (graphical representations of the entire user interface) to guide the user through the use of FAST. Chapters include: Maps, Overview, Tips, Getting Started Tutorial, a separate chapter for each module, file formats, and system administration.

Walatka, Pamela P.↗

Collaborative Resource Allocation

Collaborative Resource Allocation Networking Environment (CRANE) Version 0.5 is a prototype created to prove the newest concept of using a distributed environment to schedule Deep Space Network (DSN) antenna times in a collaborative fashion. This program is for all space-flight and terrestrial science project users and DSN schedulers to perform scheduling activities and conflict resolution, both synchronously and asynchronously. Project schedulers can, for the first time, participate directly in scheduling their tracking times into the official DSN schedule, and negotiate directly with other projects in an integrated scheduling system. A master schedule covers long-range, mid-range, near-real-time, and real-time scheduling time frames all in one, rather than the current method of separate functions that are supported by different processes and tools. CRANE also provides private workspaces (both dynamic and static), data sharing, scenario management, user control, rapid messaging (based on Java Message Service), data/time synchronization, workflow management, notification (including emails), conflict checking, and a linkage to a schedule generation engine. The data structure with corresponding database design combines object trees with multiple associated mortal instances and relational database to provide unprecedented traceability and simplify the existing DSN XML schedule representation. These technologies are used to provide traceability, schedule negotiation, conflict resolution, and load forecasting from real-time operations to long-range loading analysis up to 20 years in the future. CRANE includes a database, a stored procedure layer, an agent-based middle tier, a Web service wrapper, a Windows Integrated Analysis Environment (IAE), a Java application, and a Web page interface.

Wang, Yeou-Fang↗

Initial operating capability for the hypercluster parallel-processing test bed

The NASA Lewis Research Center is investigating the benefits of parallel processing to applications in computational fluid and structural mechanics. To aid this investigation, NASA Lewis is developing the Hypercluster, a multi-architecture, parallel-processing test bed. The initial operating capability (IOC) being developed for the Hypercluster is described. The IOC will provide a user with a programming/operating environment that is interactive, responsive, and easy to use. The IOC effort includes the development of the Hypercluster Operating System (HYCLOPS). HYCLOPS runs in conjunction with a vendor-supplied disk operating system on a Front-End Processor (FEP) to provide interactive, run-time operations such as program loading, execution, memory editing, and data retrieval. Run-time libraries, that augment the FEP FORTRAN libraries, are being developed to support parallel and vector processing on the Hypercluster. Special utilities are being provided to enable passage of information about application programs and their mapping to the operating system. Communications between the FEP and the Hypercluster are being handled by dedicated processors, each running a Message-Passing Kernel, (MPK). A shared-memory interface allows rapid data exchange between HYCLOPS and the communications processors. Input/output handlers are built into the HYCLOPS-MPK interface, eliminating the need for the user to supply separate I/O support programs on the FEP.

Cole, Gary L.↗

Mars Exploration Rover APXS Results from Matijevic Hill

Correlation analysis of APXS results on the eastern slope rocks indicate that the Matijevic Hill rocks are overall compositionally distinct from the Shoemaker Formation rocks [6]. Compared to the Shoemaker impactites, Matijevic Hill rocks are higher in Al, Si, and Ni, and lower in Ti, Fe, and Zn. No significant variation is evident in the APXS analyses that indicate the presence of a smectite or other phyllosilicate, as opposed to basaltic rocks. However, APXS data cannot in themselves rule out phyllosilicates. If indeed this material contains smectite, as seen from orbit, it implies that the rock has been isochemically altered to create the phyllosilicate content. The Cl content of the Cape York rocks is relatively high, and whereas the S/Cl ratio in the Burns Formation is 4x higher than in soil, in the Cape York rocks it is lower than in soil. These trends indicate that the alteration processes and types of aqueous salt loads were different between Cape York and Meridiani. In addition, significant deviations from the Martian Mn/Fe ratio are observed in Whitewater Lake coatings and the altered Grasford/Deadwood rocks (Fig. 3). These variations indicate that the redox/pH conditions during alteration of the Shoemaker Formation rocks and the Matijevic Hill rocks were similar, but that the Deadwood/Grasberg unit may have undergone alteration under different conditions, possibly at a later time. The Matijevic Hill outcrops appear to share a common genetic origin. It is not yet clear whether both the Shoemaker impactites and Matijevic Hill rocks are related to the formation of Endeavour Crater, or whether the Matijevic Hill suite represents a prior episode of Martian impact or volcanism. Opportunity continues to investigate both hypotheses.

Cohen, B. A.↗

LaRC local area networks to support distributed computing

The Langley Research Center's (LaRC) Local Area Network (LAN) effort is discussed. LaRC initiated the development of a LAN to support a growing distributed computing environment at the Center. The purpose of the network is to provide an improved capability (over inteactive and RJE terminal access) for sharing multivendor computer resources. Specifically, the network will provide a data highway for the transfer of files between mainframe computers, minicomputers, work stations, and personal computers. An important influence on the overall network design was the vital need of LaRC researchers to efficiently utilize the large CDC mainframe computers in the central scientific computing facility. Although there was a steady migration from a centralized to a distributed computing environment at LaRC in recent years, the work load on the central resources increased. Major emphasis in the network design was on communication with the central resources within the distributed environment. The network to be implemented will allow researchers to utilize the central resources, distributed minicomputers, work stations, and personal computers to obtain the proper level of computing power to efficiently perform their jobs.

Riddle, E. P.↗

Aids to School Bus Design

Navistar International Transportation Corporation, Chicago, IL, used three separate NASA-developed technologies in the design and testing of their 3000 Series Bus Chassis which was developed expressly for school bus applications. For structural analysis, they used the MSC/NASTRAN program which mathematically analyzes a design and predicts how it will hold up under stress. They also used the SPATE 9000 system for non-contact measurement of stress, load transfer mechanisms, detection of hidden flaws, and monitoring structural changes during fatigue testing. SPATE 9000 was based on infrared stress measurement technology developed by Langley Research Center. They also employed the Wyle Ride Quality Meter, which was developed by Langley to aid in passenger aircraft design by providing an accurate measurement of ride vibration and sound level. These numbers translate into a subjective discomfort level index. These technologies contribute to the company's 45-48 percent share of the school bus chassis market.

Source record↗

Evaluation of the constant pressure panel method (CPM) for unsteady air loads prediction

This paper evaluates the capability of the constant pressure panel method (CPM) code to predict unsteady aerodynamic pressures, lift and moment distributions, and generalized forces for general wing-body configurations in supersonic flow. Stability derivatives are computed and correlated for the X-29 and an Oblique Wing Research Aircraft, and a flutter analysis is carried out for a wing wind tunnel test example. Most results are shown to correlate well with test or published data. Although the emphasis of this paper is on evaluation, an improvement in the CPM code's handling of intersecting lifting surfaces is briefly discussed. An attractive feature of the CPM code is that it shares the basic data requirements and computational arrangements of the doublet lattice method. A unified code to predict unsteady subsonic or supersonic airloads is therefore possible.

Appa, Kari↗

Next Steps Toward Understanding Human Habitation of Space: Environmental Impacts and Mechanisms

Entry into low earth orbit and beyond causes profound shifts in environmental conditions that have the potential to influence human productivity, long term health, and even survival. We now have evidence that microgravity, radiation and/or confinement in space can lead to demonstrably detrimental changes in the cardiovascular (e.g. vessel function, orthostatic intolerance), musculoskeletal (muscle atrophy, bone loss) and nervous (eye, neurovestibular) systems of astronauts. Because of both the limited number of astronauts who have flown (especially females) and the high degree of individual variability in the human population, important unanswered questions about responses to the space environment remain: What are the sex differences with respect to specific physiological systems? Are the responses age-dependent and/or reversible after return to Earth? Do observed detrimental changes that resemble accelerated aging progress continuously over time or plateau? What are the mechanisms of the biological responses? Answering these important questions certainly demands a multi-pronged approach, and the study of multicellular model organisms (such as rodents and flies) already has provided opportunities for exploring those questions in some detail. Recent long duration spaceflight experiments with rodents show that mice in space provide a mammalian model that uniquely combines the influence of reduced gravitational loading with increased physical activity. In addition, multiple investigators have shown that ground-based models that simulate aspects of spaceflight (including rodent hind limb unloading to mimic weightlessness and exposure to ionizing radiation), cause various transient and persistent detrimental consequences in multiple physiological systems. In general, we have found that adverse skeletal effects of simulated weightlessness and space radiation when combined, can be quantitatively, if not qualitatively, different from the influence of each environmental factor alone implying at least some shared underlying mechanisms. Thus, both ground based and spaceflight research utilizing model organisms provide the opportunity to better understand environmental factors and biological mechanisms that contribute to human health and survival in space.

skeleton↗

Crystallographic and general use programs for the XDS Sigma 5 computer

Programs in basic FORTRAN 4 are described, which fall into three catagories: (1) interactive programs to be executed under time sharing (BTM); (2) non interactive programs which are executed in batch processing mode (BPM); and (3) large non interactive programs which require more memory than is available in the normal BPM/BTM operating system and must be run overnight on a special system called XRAY which releases about 45,000 words of memory to the user. Programs in catagories (1) and (2) are stored as FORTRAN source files in the account FSNYDER. Programs in catagory (3) are stored in the XRAY system as load modules. The type of file in account FSNYDER is identified by the first two letters in the name.

Snyder, R. L.↗

SWIRP (Submm-Wave and Long Wave InfraRed Polarimeter); Development and Characterization of a Sub-Mm Polarimeter for Ice Cloud Investigations

A major source of uncertainty in climate models is the presence, shape and distribution of ice particles in the uppermost layers of the clouds. The effects of this component are poorly constrained, turning ice particles into an almost-free variable in many climate models.NASA-GSFC is developing a new instrument aimed at measuring the size and shape of ice particles. The instrument consists of two sub-mm polarimeters (at 220 and 670 GHz) coupled with a long-wave infrared polarimeter at 10 micron. Each polarimeter has identical V-pol and H-pol channels; the axes of polarization are defined geometrically by the orientation of the waveguide elements, and the purity has been measured in the lab. The instrument is configured as a conical scanner, suitable for deployment as a payload on a small satellite or on a high-altitude sub-orbital platform. From a 400 km orbit, the instrument has a 3dB spatial resolution of 20 (10) km at 220 (670) GHz and a swath of 600 km over 180 degrees of view.The BAPTA (Bearing And Power Transfer Assembly) carries heritage from the SSMIS design, now in its 22nd year of on-orbit operation, but with a much reduced SWaP (Size Weight and Power) footprint, suitable for a small satellite.The main components of the instrument have been fabricated and are undergoing final testing prior to their integration as a single unit. The sub-mm channels have dedicated secondary reflectors which illuminate a shared primary reflector. The receiving units are placed behind the focal point of the optical arrangement, so that all beams equally illuminate the primary reflector and are almost co-located on the ground (within a single 220 GHz footprint). Primary and secondary beam patterns have been measured and verified to match the as-designed expectations. A Zytex (TM) window is deployed to protect the secondary reflectors and the feed horns from debris and other contaminants, and to reduce the heat load from the active (hot) IR calibration unit. The insertion loss of Zytex has been measured and is accounted in the calibration equation of the sub-mm channels.The radiometric performance of the sub-mm receivers has been characterized in the lab and under operational conditions of temperature and pressure.This paper discusses the design constraints on the sub-mm components, details of the scientific goals and their flowdown, and describes the characterization of the polarimeters. Options to optimize the layout and distribution of the masses within the assembly, with the goal of making the instrument even more compact and fully-compatible with cubesat-class satellites will be presented.

De Amici, G.↗

Journal of Gravitational Physiology, Volume 12, Number 1

The following topics were covered: System Specificity in Responsiveness to Intermittent -Gx Gravitation during Simulated Microgravity in Rats; A Brief Overview of Animal Hypergravity Studies; Neurovestibular Adaptation to Short Radius Centrifugation; Effect of Artificial Gravity with Exercise Load by Using Short-Arm Centrifuge with Bicycle Ergometer as a Countermeasure Against Disused Osteoporosis; Perception of Body Vertical in Microgravity during Parabolic Flight; Virtual Environment a Behavioral and Countermeasure Tool for Assisted Gesture in Weightlessness: Experiments during Parabolic Flight; Artificial Gravity: Physiological Perspectives for Long-Term Space Exploration; Comparison of the Effects of DL-threo-Beta-Benzyloxyaspartate on the Glutamate Release from Synaptosomes before and after Exposure of Rats to Artificial Gravity; Do Perception and Postrotatory Vestibulo-Ocular Reflex Share the Same Gravity Reference?; Vestibular Adaptation to Changing Gravity Levels and the Orientation of Listing's Plane; Compound Mechanism Hypothesis on +Gz - Induced Brain Injury and Dysfunction of Learning and Memory; Environmental Challenge Impairs Prefrontal Brain Functions; Effect of 6-Days of Support Withdrawal on Characteristics of Balance Function; Hypergravity-Induced Changes of Neuronal Activities in CA1 Region of Rat Hippocampus; Audiological Findings in Antiorthostatic Position Modelling Microgravitation; Investigating Human Cognitive Performance during Spaceflight; The Relevance of the Minimization of Torque Exchange with the Environment in Weightlessness is Confirmed by Asimulation Study; Characteristics of the Eyes Pursuit Function during Readaptation to Terrestrial Gravity after Prolonged Flights Aboard the International Space Station; Comparison of Cognitive Performance Tests for Promethazine Pharmacodynamics in Human Subjects; Structural Reappraisal of Dendritic Tree of Cerebellar Purkinje Cell for Novel Functional Modeling of Elementary Sensorimotor Adaptive Processes; Orpheus 0 G or Ear in Microgravity to Establish Symptoms Concomittant of Inner and Middle Ear and Osteoporosis in Microgravity; Understanding Visual Perception in the Perspective of Gravity; Cortical Regions Associated with Orthostatic Stress in Conscious Humans; Restoration of Central Blood Volume: Application of a Simple Concept and Simple Device to Counteract Cardiovascular Instability in Syncope and Hemorrhage; WISE-2005: Integrative Cardiovascular Responses with LBNP during 60-Day Bed Rest in Women; Intracranial Pressure Increases during Weightlessness. A Parabolic Flights Study; Lower Limb & Portal Veins Echography for Predicting Risk of Thrombosis during a 90-D Bed Rest; Calf Tissue Liquid Stowage and Muscular and Deep Vein Distension in Orthostatic Tests after a 90-Day Head Down Bed Rest; Morphology of Brain Vessels in the Tail Suspended Rats Exposed to Intermittent 2 G; Alterations in Vasoreactivity of Femoral Artery Induced by Hindlimb Unweighting are Related to the Changes of Contractile Protein in Rats; and Respiratory Sinus Arrhythmia: A Marker of Decreased Parasympathetic Modulation after Short Duration.

Fuller, Charles A.↗

Application of a dedicated micro-processor for automatic data acquisition of load strain and acoustic-emission data

This paper describes an automatic system for acquisition, logging and analysis of stress, strain and acoustic emission data. The complete system is a combination of several standard items of equipment and a newly developed intelligent data logger which has the capability to send data directly to a large scale computer for reduction and plotting. The data logging and all interfacing with peripheral equipment are accomplished using digital electronics. The heart of the system is a four-bit microprocessor and digital cassette tape unit. The system, which is controlled by instructions from a cathode ray tube terminal, has the capability to transmit data from the cassette unit to a large computer via a time sharing option. Typical results are presented for acoustic emission count rate and total count curves superimposed on stress-strain diagrams for boron/epoxy advanced composites.

Wilson, G. H.↗

The KALI multi-arm robot programming and control environment

The KALI distributed robot programming and control environment is described within the context of its use in the Jet Propulsion Laboratory (JPL) telerobot project. The purpose of KALI is to provide a flexible robot programming and control environment for coordinated multi-arm robots. Flexibility, both in hardware configuration and software, is desired so that it can be easily modified to test various concepts in robot programming and control, e.g., multi-arm control, force control, sensor integration, teleoperation, and shared control. In the programming environment, user programs written in the C programming language describe trajectories for multiple coordinated manipulators with the aid of KALI function libraries. A system of multiple coordinated manipulators is considered within the programming environment as one motion system. The user plans the trajectory of one controlled Cartesian frame associated with a motion system and describes the positions of the manipulators with respect to that frame. Smooth Cartesian trajectories are achieved through a blending of successive path segments. The manipulator and load dynamics are considered during trajectory generation so that given interface force limits are not exceeded.

Backes, Paul↗

NASA Environmentally Responsible Aviation High Overall Pressure Ratio Compressor Research Pre-Test CFD

This paper describes a collaborative and cost-shared approach to reducing fuel burn under the NASA Environmentally Responsible Aviation project. NASA and General Electric (GE) Aviation are working together aa an integrated team to obtain compressor aerodynamic data that is mutually beneficial to both NASA and GE Aviation. The objective of the High OPR Compressor Task is to test a single stage then two stages of an advanced GE core compressor using state-of-the-art research instrumentation to investigate the loss mechanisms and interaction effects of embedded transonic highly-loaded compressor stages. This paper presents preliminary results from NASA's in-house multistage computational code, APNASA, in preparation for this advanced transonic compressor rig test.

Celestina, Mark L.↗

The use of carboranes as oxidation inhibitors for carbon-carbon composites

Carbon-carbon composites have many beneficial properties for use in aerospace applications, including their high specific strength and modulus at elevated temperatures. However, they share with all carbon based substances a strong tendency to burn when heated in air. In order to exploit their good qualities, it is necessary to slow or prevent their oxidation during use. Molecular inhibiters offer protection with the advantage of being able to form a homogeneous solution with the resin. Since boron oxides are known to provide the desired kind of protection, molecular compounds based on boron seem reasonable candidates to test as inhibitors. Performance tests indicated that carboranes are excellent materials for obtaining high uniform loadings of boron inhibitors in glassy carbon materials and thus reducing their rates of oxidation. Further, there is evidence that the use of substituted derivatives could provide more complete and thorough forms of protection.

Petty, John T.↗

Estimating lithospheric properties at Atla Regio, Venus

Magellan spehrical harmonic gravity and topography models are used to estimate lithospheric properties at Alta Regio, Venus, a proposed hotspot with dynamic support from mantle plume(s). Global spherical harmonic and local representations of the gravity field share common properties in the Atla region interms of their spectral behavior over a wavelength band from approximately 2100 to approximately 700 km. The estimated free-air admittance spectrum displays a rather featureless long-wavelength portion followed by a sharp rise at wavelengths shorter than about 1000 km. This sharp rise requires significant flexural support of short-wavelength structures. The Bouguer coherence also displays a sharp drop in this wavelength band, indicating a finite flexural rigidity of the lithosphere. A simple model for lithospheric loading from above and below is introduced (D. W. Forsyth, 1985) with four parameters: f, the ratio of bottom loading to top loading; z(sub m), crustal thickness; z(sub l) depth to bottom loading source; and T(sub e) elastic lithosphere thickness. A dual-mode compensation model is introduced in which the shorter wavelengths (lambda approximately less than 1000 km) might be explained best by a predominance of top loading by the large shield volcanoes Maat Mons, Ozza Mons, and Sapas Mons, and the longer wavelengths (lambda approximately greater than 1500 km) might be explained best by a deep depth of compensation, possibly representing bottom loading by a dynamic source. A Monte Carlo inversion technique is introduced to thoroughly search out the four-space of the model parameters and to examine parameter correlation in the solutions. Venus either is a considerabe deficient in heat sources relative to Earth, or the thermal lithosphere is overthickened in response to an earlier episode of significant heat loss from the planet.

Phillips, Roger J.↗

Flight Performance and Stability of Space Launch System Core Stage Thrust Vector Control

The Space Launch System (SLS) Core Stage (CS) Thrust Vector Control (TVC) system is comprised of eight mechanical feedback Shuttle heritage Type III TVC actuators and four RS-25 engines, each attached to a Shuttle heritage gimbal block/bearing. The Core Stage TVC shares vehicle control authority with the SLS 5-segment Solid Rocket Boosters (SRBs) during boost phase flight, and is the sole means of vehicle flight control during in exoatmospheric flight following SRB separation. TVC responses during Green Run Hot Fire (GRHF) testing revealed that the TVC did not meet its performance specifications. Step and frequency responses exhibited unexpected departures from prior laboratory data and modeled behavior. Post-test analysis determined that the characteristics of the structure and gimbal friction are significantly influenced by the thrust-loaded conditions, and the command avionics exhibited a small but important gain nonlinearity. Using the available test data, the design team augmented the flight control TVC models to bound the observed results and include the additional fidelity needed for vehicle flight control analysis so as to build sufficient rationale for flight certification. Prior to the Green Run tests, “simplex” linear models typically used for flight control analysis did not include gimbal friction and other nonlinearities owing to long-standing assumptions that these effects were negligible in the Shuttle Orbiter TVC system. Following the Green Run findings, simulation analysis of the flight dynamics in the time and frequency domain revealed the propensity for a flight control limit cycle oscillation (LCO) if friction and structural compliances fell near the edges of test-predicted bounds. While the “most probable” models did not predict an in-flight LCO, the SLS Program conservatively proceeded with a system-wide evaluation and ultimate acceptance of the possibility for a small amplitude, low-frequency TVC LCO in flight. A final validation of the extensive test and modeling effort occurred when the first flight of SLS successfully demonstrated the fully integrated performance of the vehicle’s TVC system This paper is the final installment in a seven-paper series surveying the design, engineering, test validation, and flight performance of the Core Stage Thrust Vector Control system. In this paper, the development of flight rationale in light of the TVC responses observed in Green Run is discussed, along with a review of the flight telemetry illustrating the correlation of the preflight predictions with the observed performance.

John H. Wall↗