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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

A scheduling and resource management system for space applications

Every spacecraft, whether in orbit around the earth or an a deep space flight, has at its disposal limited amounts of the resources for it to accomplish its mission. Activity scheduling is currently a costly, human intensive task which requires a great deal of expertise. It belongs to a class of problems whose complexity increases exponentially with the number of operations. NASA has in the past accomplished this task by using a great deal of manpower, a large number of negotiating sessions, interminable bouts of phone tag, and mountains of paperwork. Lately the situation has improved with the introduction of automated scheduling techniques, but these to date still require expert involvement and fall short in some important ways. A prototype activity scheduler, MAESTRO, is introduced which is capable of meeting the needs of many NASA missions, eventually to include the Space Station. The approach to resource constrained scheduling is first discussed, then the intended domain for MAESTRO is described along with its design and current capabilities. A description of planned enhancements and revisions to the systems is also presented.

Britt, Daniel L.↗
NASA NTRS1982

Hybrid Position/Force Control of Robot Manipulators

In proposed method for task-oriented control of robot manipulator, position and force error signals for each task degree of freedom are used to calculate appropriate control parameters in task coordinates. Position and force error signals are transformed and summed to create drive signal for each actuator. New hybrid control technique does not require operator to supply complex transform matrices. Control trajectories are easily visualized in terms of task to be performed.

Raibert, M. H.↗
DOE OSTI2026

WM26 Paper Multi-Robot Collaboration for Hazardous Environments

Hazardous nuclear and industrial facilities are rarely designed for robots. Work in these domains demand precise manipulation and robust mobility in cluttered, constrained spaces where off-the-shelf platforms struggle and “one-size-fits-all” machines become costly and complex. Idaho National Laboratory (INL) is developing an autonomous, multi-robot inspection system that coordinates task-specific platforms rather than relying on a single omni-tool robot. An electric truck serves as a power and compute hub for a custom manipulator co-developed with Florida International University (FIU), a commercial mini crawler, a pan–tilt–zoom camera, and a Nexxis Argus LiDAR mapping system. Working in concert, these robots generate spatial, radiation, and temperature maps of the pit environments at the Hanford Waste Tank Farms. These systems will capture visual records and environmental telemetry to allow for analysis post inspection. The system architecture uses Robot Operating System 2 (ROS 2) for publish/subscribe integration, NVIDIA Isaac Sim and Unity for simulation and visualization, and algorithms such as NVBlox to fuse data into unified 3D overlays. This robot-agnostic approach reduces operator burden by enabling autonomy across heterogeneous platforms and lets each robot be used where it is strongest. Having autonomous functions means operators don’t have to fully control multiple different components. The ease of use could allow for more widespread adoption of advanced robotics at waste management sites that see continued use. By coordinating simpler, purpose-built mechanisms, the approach lowers design and manufacturing complexity, reduces capital risk in contaminated settings, and improves controllability for complex inspection and manipulation tasks. We present the architecture, early results, and lessons learned from building and deploying this coordinated multi-robot system, with the goal of accelerating safe, cost-effective adoption of advanced robotics at waste-management sites.

42 - ENGINEERING↗
NASA NTRS1990

Task-dependent color discrimination

When color video displays are used in time-critical applications (e.g., head-up displays, video control panels), the observer must discriminate among briefly presented targets seen within a complex spatial scene. Color-discrimination threshold are compared by using two tasks. In one task the observer makes color matches between two halves of a continuously displayed bipartite field. In a second task the observer detects a color target in a set of briefly presented objects. The data from both tasks are well summarized by ellipsoidal isosensitivity contours. The fitted ellipsoids differ both in their size, which indicates an absolute sensitivity difference, and orientation, which indicates a relative sensitivity difference.

Poirson, Allen B.↗
NASA NTRS1999

Alternative Architectures for Distributed Cooperative Problem-Solving in the National Airspace System

The air traffic management system in the United States is an example of a distributed problem solving system. It has elements of both cooperative and competitive problem-solving. This system includes complex organizations such as Airline Operations Centers (AOCs), the FAA Air Traffic Control Systems Command Center (ATCSCC), and traffic management units (TMUs) at enroute centers and TRACONs, all of which have a major focus on strategic decision-making. It also includes individuals concerned more with tactical decisions (such as air traffic controllers and pilots). The architecture for this system has evolved over time to rely heavily on the distribution of tasks and control authority in order to keep cognitive complexity manageable for any one individual operator, and to provide redundancy (both human and technological) to serve as a safety net to catch the slips or mistakes that any one person or entity might make. Currently, major changes are being considered for this architecture, especially with respect to the locus of control, in an effort to improve efficiency and safety. This paper uses a series of case studies to help evaluate some of these changes from the perspective of system complexity, and to point out possible alternative approaches that might be taken to improve system performance. The paper illustrates the need to maintain a clear understanding of what is required to assure a high level of performance when alternative system architectures and decompositions are developed.

Smith, Phillip J.↗
DOE OSTI2019

Design of an experimental facility with a unit cell test section for studies of the lower plenum in prismatic high temperature gas reactors

A proposed design for a Generation IV reactor is the very-high temperature reactor (VHTR), which employs helium as the primary coolant. Although many advantages exist with this design, a number of challenges remain. One such area of concern is the turbulent mixing of non-isothermal flows in the lower plenum, where an array of coolant jets collectively mix and traverse around a series of structural support posts before exiting the core. Neighboring jets in the lower plenum could experience temperature differences as high as 300–400 K, causing potential hot streaking in the support posts. Additional problems could occur further downstream if the level of non-uniformity in the temperatures is too high (e.g, inducing thermal stresses on gas turbine blades). Therefore, it is important that adequate tools exist to predict the turbulent mixing within the VHTR lower plenum. This task remains difficult to achieve due to the complex geometry and flow physics that dictate the mixing. Various modeling approaches can only be assessed using data acquired from a carefully designed experimental facility. This paper presents details of such a facility, where high-fidelity measurements can be acquired for a scaled portion of the lower plenum defined herein as a ‘‘unit cell”, which consists of a hexagonal array of jets whose flow is directed into a test section with support posts positioned between neighboring jets, and subjected to a crossflow. Through adjusting velocity and temperature conditions at the jet inlets, different locations within the lower plenum can be experimentally simulated. System response quantities (SRQs) include both temperature and velocity measurements, captured via multiple thermocouples embedded in each post, and particle image velocimetry (PIV), respectively. These SRQs provide assessment metrics for both the momentum and energy models present in current computational solvers, and therefore the experimental facility is a valuable source for validation data. Another benefit is a more comprehensive understanding of the thermal-hydraulic loading conditions and flow physics present in the VHTR lower plenum.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Decoding the protein–ligand interactions using parallel graph neural networks

Abstract Protein–ligand interactions (PLIs) are essential for biochemical functionality and their identification is crucial for estimating biophysical properties for rational therapeutic design. Currently, experimental characterization of these properties is the most accurate method, however, this is very time-consuming and labor-intensive. A number of computational methods have been developed in this context but most of the existing PLI prediction heavily depends on 2D protein sequence data. Here, we present a novel parallel graph neural network (GNN) to integrate knowledge representation and reasoning for PLI prediction to perform deep learning guided by expert knowledge and informed by 3D structural data. We develop two distinct GNN architectures: $$\hbox {GNN}_{\mathrm{F}}$$ GNN F is the base implementation that employs distinct featurization to enhance domain-awareness, while $$\hbox {GNN}_{\mathrm{P}}$$ GNN P is a novel implementation that can predict with no prior knowledge of the intermolecular interactions. The comprehensive evaluation demonstrated that GNN can successfully capture the binary interactions between ligand and protein’s 3D structure with 0.979 test accuracy for $$\hbox {GNN}_{\mathrm{F}}$$ GNN F and 0.958 for $$\hbox {GNN}_{\mathrm{P}}$$ GNN P for predicting activity of a protein–ligand complex. These models are further adapted for regression tasks to predict experimental binding affinities and $$\hbox {pIC}_{\mathrm{50}}$$ pIC 50 crucial for compound’s potency and efficacy. We achieve a Pearson correlation coefficient of 0.66 and 0.65 on experimental affinity and 0.50 and 0.51 on $$\hbox {pIC}_{\mathrm{50}}$$ pIC 50 with $$\hbox {GNN}_{\mathrm{F}}$$ GNN F and $$\hbox {GNN}_{\mathrm{P}}$$ GNN P , respectively, outperforming similar 2D sequence based models. Our method can serve as an interpretable and explainable artificial intelligence (AI) tool for predicted activity, potency, and biophysical properties of lead candidates. To this end, we show the utility of $$\hbox {GNN}_{\mathrm{P}}$$ GNN P on SARS-Cov-2 protein targets by screening a large compound library and comparing the prediction with the experimentally measured data.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Toward Quantifying Vulnerabilities in Critical Infrastructure Systems

Modern society is increasingly dependent on the stability of a complex system of interdependent infrastructure sectors. Vulnerability in critical infrastructures (CIs) is defined as a measure of system susceptibility to threat scenarios. Quantifying vulnerability in CIs has not been adequately addressed in the literature. This paper presents ongoing research on how the authors model CIs as network-based models and propose a set of metrics to quantify vulnerability in CI systems. The size and complexity of the CIs make this a challenging task. These metrics could be used for planning and efficient decision-making during extreme events.

Devineni, Pravallika↗
DOE OSTI2024

Optimization and Evaluation of Energy Savings for Connected and Autonomous Off-Road Vehicles

Off-road vehicles, such as wheel loaders, excavators, and harvesters, are extensively utilized across a wide range of industries, including construction, agriculture, and mining. These machines have become indispensable in supporting the day-to-day operational needs of a nation, playing a critical role in various sectors' infrastructure and productivity. However, despite their utility, off-road vehicles are significant consumers of fossil fuels, resulting in substantial emissions that contribute to environmental degradation. This highlights the pressing need for research and technological advancements aimed at improving their energy efficiency and reducing their carbon footprint. There are, however, two primary challenges that must be addressed to achieve these goals. First, off-road vehicles typically perform both driving and working tasks simultaneously, which introduces a high level of complexity into their overall dynamic systems. Analysis the interactions between these functions is challenging. Second, research into off-road vehicles is inherently interdisciplinary, demanding expertise across several domains such as fluid power systems, vehicle dynamics, control theory, optimization techniques, and real-world implementation. Recognizing these challenges, we proposed the project titled "Optimization and Evaluation of Energy Savings for Connected and Autonomous Off-Road Vehicles" as a comprehensive solution to enhance fuel efficiency while simultaneously improving productivity. This project specifically focuses on autonomous off-road vehicles, with particular attention to wheel loaders, and seeks to develop novel methods to optimize energy consumption without sacrificing operational performance. The project integrates real-time control algorithms, vehicle dynamics modeling, and co-optimization of powertrain system and vehicle system to achieve these goals. Our optimization strategy dynamically co-optimizes critical parameters at both the powertrain and vehicle levels, including vehicle speed, working tool movements, powertrain dynamics, and engine operations in real-time. To streamline this optimization process, we developed a vehicle model that captures the key dynamics while significantly enhancing computational efficiency. This allows the system to intelligently minimize fuel consumption, all while maintaining or even improving productivity through real-time calculations during various off-road operations. To validate the effectiveness of this energy optimization method, we introduced a state-of-the-art Hardware-in-the-Loop (HIL) testbed. This reconfigurable testbed seamlessly integrates the actual engine with virtual models of the wheel loader's subsystems, allowing for accurate emulation of real-world operational loads and environments. By simulating these conditions, the HIL testbed enables us to evaluate the wheel loader’s performance under diverse working scenarios, ensuring the developed solution is applicable in real-world operations. This testbed proved to be instrumental in validating the optimization algorithms and demonstrating the system's practical effectiveness. During the evaluation and testing phase, we employed the HIL testbed to rigorously assess the energy savings and productivity improvements generated by the optimized system. The results were highly encouraging, revealing that the automated wheel loader achieved over 30% fuel savings compared to traditional, human-operated cycles, with comparable or even enhanced levels of productivity. The insights gained from this HIL-based testing provided critical validation of our approach and highlighted the potential for deploying these optimized autonomous technologies in real-world off-road vehicles.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1971

ALSEP data management.

Nine million measurements a day are transmitted from each functional ALSEP on the moon and continuously collected on earth for use in long-term scientific analysis. Periodically, this massive flow of intricate data is examined on a real-time basis to evaluate ALSEP performance and to study the need for new commands to any of the ALSEP systems. A worldwide complex of facilities and personnel has the challenging task of efficient and timely data processing and dissemination. This paper describes facility characteristics and support activities and details certain constraints imposed on ALSEP hardware design by data handling requirements. The highlights of the first two years of lunar data management are reviewed.

Murtaugh, C. R.↗
NASA NTRS1972

The systematic evolution of a NASA software technology, Appendix C

A long range program is described whose ultimate purpose is to make possible the production of software in NASA within predictable schedule and budget constraints and with major characteristics such as size, run-time, and correctness predictable within reasonable tolerances. As part of the program a pilot NASA computer center will be chosen to apply software development and management techniques systematically and determine a set which is effective. The techniques will be developed by a Technology Group, which will guide the pilot project and be responsible for its success. The application of the technology will involve a sequence of NASA programming tasks graduated from simpler ones at first to complex systems in late phases of the project. The evaluation of the technology will be made by monitoring the operation of the software at the users' installations. In this way a coherent discipline for software design, production maintenance, and management will be evolved.

Deregt, M. P.↗
NASA NTRS1975

Handbook for preparation of work breakdown structures

Guidelines are presented for development of work breakdown structures (WBS) for NASA programs, projects, and contracts. The WBS were developed by starting with the end objective required and successively subdividing it into manageable components in terms of size and complexity, such as program, project, system, subsystems, components, tasks, subtasks, and work elements.

Source record↗
NASA NTRS1979

Advanced teleoperators

Advanced teleoperators are discussed, with emphasis on the remote manipulation system designed to perform such actions as grasping, orienting, moving, placing, and inserting objects. Geometrical performance dimensions are considered, indicating that a manipulator is limited to three-orders-of-magnitude ratio of workspace extension to positioning accuracy. The control system is examined, showing that a manipulative task requires coordination of several joints, with the relationship between the task definers and the joint variables given by complex trigonometrical transformations. Control modes developed in the last 30 years are noted, including program controlled industrial 'robots' which can endlessly repeat a fixed sequence of motions without operator intervention, and the sensor-referenced/computer-controlled mode manipulators. Advanced proximity sensor systems are taken into account, with emphasis on the applications of the force-torque and slip models. The proximity sensor system for the shuttle-size manipulator is described.

Bejczy, A. K.↗
NASA NTRS1988

System analysis in rotorcraft design: The past decade

Rapid advances in the technology of electronic digital computers and the need for an integrated synthesis approach in developing future rotorcraft programs has led to increased emphasis on system analysis techniques in rotorcraft design. The task in systems analysis is to deal with complex, interdependent, and conflicting requirements in a structured manner so rational and objective decisions can be made. Whether the results are wisdom or rubbish depends upon the validity and sometimes more importantly, the consistency of the inputs, the correctness of the analysis, and a sensible choice of measures of effectiveness to draw conclusions. In rotorcraft design this means combining design requirements, technology assessment, sensitivity analysis and reviews techniques currently in use by NASA and Army organizations in developing research programs and vehicle specifications for rotorcraft. These procedures span simple graphical approaches to comprehensive analysis on large mainframe computers. Examples of recent applications to military and civil missions are highlighted.

Galloway, Thomas L.↗
NASA NTRS1988

Model of Jovian F region ionosphere

To date, seven electron density profiles of the Jovian ionosphere have been furnished by the radio occultation experiments aboard the Pioneer and Voyager space probes. The data correspond to various localities (latitudes and longitudes) and times (dawn and dusk) and phases of sunspot cycle (high and low). This renders comparative studies difficult. Nevertheless, the possibility of existence of diurnal variation, equatorial anomaly, and auroral particle precipitation in the Jovian ionosphere have been put forth. The grand magnitude and depth of the equatorial anomaly, in particular, is a matter of great interest and speculation. Correct interpretations of the data and the physical processes in the complex Jovian atmospheric environment will remain a major task for the Aeronomer for decades to come. Model studies of a Jovian ionosphere created by solar EUV radiation and subjected to model ExB drifts showed that equatorial anomaly similar to that in the terrestrial ionosphere can indeed be produced in the Jovian ionosphere. However, owing to the difference in size and rotation period of the two planets and the ionic compositions, much larger drift velocities are required to produce a comparable anomaly in the Jovian atmosphere.

Tan, A.↗
NASA NTRS1987

Trends in Space Station telemetry applications

Spacecraft telemetry systems have evolved from simple hardware devices to complex computer applications performing data acquisition and formatting tasks. This paper reviews the role of spacecraft computers in performing telemetry functions and examines computer-based telemetry systems being considered for use on the NASA Space Station.

Muratore, John F.↗
NASA NTRS1992

Importance of numerosity and distribution of articulations within the digits, wrists, and arms of telemanipulators confronted with dextrous assembly tasks

This study was conducted to evaluate the impact of successive exclusion of degrees-of-freedom within digits (thumb and index finger) and wrist when performing tasks demanding varying degrees of end effector kinematic complexity. The analysis was performed by successive constraining articulations in the fingers (thumb and index) and wrists or human subjects via splints, and then timing performance of part movement, positioning, and assembly operations requiring different levels of kinematic freedom. Analysis of performance times showed that transferring degrees-of-freedom, or articulations, from the digits to the wrist and arm had little or no material affect upon manipulation performance times if wrist and arm kinematics were unrestricted. If wrist and arm kinematics are not constrained and are of high-quality, our findings show that transferring kinematic freedom from the digits to the wrist and arms or remote end effectors offers limited or no consequence in terms of remote assembly operations. The importance of such findings, in terms of development and implementation of commercially attractive telemanipulators, is discussed.

Wiker, Steven F.↗
NASA NTRS1992

A domain-specific design architecture for composite material design and aircraft part redesign

Advanced composites have been targeted as a 'leapfrog' technology that would provide a unique global competitive position for U.S. industry. Composites are unique in the requirements for an integrated approach to designing, manufacturing, and marketing of products developed utilizing the new materials of construction. Numerous studies extending across the entire economic spectrum of the United States from aerospace to military to durable goods have identified composites as a 'key' technology. In general there have been two approaches to composite construction: build models of a given composite materials, then determine characteristics of the material via numerical simulation and empirical testing; and experience-directed construction of fabrication plans for building composites with given properties. The first route sets a goal to capture basic understanding of a device (the composite) by use of a rigorous mathematical model; the second attempts to capture the expertise about the process of fabricating a composite (to date) at a surface level typically expressed in a rule based system. From an AI perspective, these two research lines are attacking distinctly different problems, and both tracks have current limitations. The mathematical modeling approach has yielded a wealth of data but a large number of simplifying assumptions are needed to make numerical simulation tractable. Likewise, although surface level expertise about how to build a particular composite may yield important results, recent trends in the KBS area are towards augmenting surface level problem solving with deeper level knowledge. Many of the relative advantages of composites, e.g., the strength:weight ratio, is most prominent when the entire component is designed as a unitary piece. The bottleneck in undertaking such unitary design lies in the difficulty of the re-design task. Designing the fabrication protocols for a complex-shaped, thick section composite are currently very difficult. It is in fact this difficulty that our research will address.

Punch, W. F., III↗