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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Direct formulation of a 4-node hybrid shell element with rotational degrees of freedom

A simple 4-node assumed-stress hybrid quadrilateral shell element with rotational or 'drilling' degrees of freedom is formulated. The element formulation is based directly on a 4-node element rather than being derived from an 'internal' 8-node isoparametric element. The formulation is based on the principle of minimum complementary energy. The membrane part of the element has 12 degrees of freedom. The bending part of the element also has 12 degrees of freedom. The bending part of the element uses the Reissner-Mindlin plate theory which takes into account the transverse shear effects. Quadratic variations for both in-plane and out-of-plane displacement fields and linear variations for both in-plane and out-of-plane rotation fields are assumed along the edges of the element. The element passes the patch test, is nearly insensitive to mesh distortion, has no spurious modes, and is invariant with respect to node numbering.

Aminpour, Mohammad A.↗
NASA NTRS1992

An assumed-stress hybrid 4-node shell element with drilling degrees of freedom

An assumed-stress hybrid/mixed 4-node quadrilateral shell element is introduced that alleviates most of the deficiencies associated with such elements. The formulation of the element is based on the assumed-stress hybrid/mixed method using the Hellinger-Reissner variational principle. The membrane part of the element has 12 degrees of freedom including rotational or 'drilling' degrees of freedom at the nodes. The bending part of the element also has 12 degrees of freedom. The bending part of the element uses the Reissner-Mindlin plate theory which takes into account the transverse shear contributions. The element formulation is derived from an 8-node isoparametric element by expressing the midside displacement degrees of freedom in terms of displacement and rotational degrees of freedom at corner nodes. The element passes the patch test, is nearly insensitive to mesh distortion, does not 'lock', possesses the desirable invariance properties, has no hidden spurious modes, and for the majority of test cases used in this paper produces more accurate results than the other elements employed herein for comparison.

Aminpour, M. A.↗
NASA NTRS1993

Space station freedom resource nodes internal thermal control system

This paper presents an overview of the design and operation of the internal thermal control system (ITCS) developed for Space Station Freedom by the NASA-Johnson Space Center and McDonnell Douglas Aerospace to provide cooling for the resource nodes, airlock, and pressurized logistics modules. The ITCS collects, transports and rejects waste heat from these modules by a dual-loop, single-phase water cooling system. ITCS performance, cooling, and flow rate requirements are presented. An ITCS fluid schematic is shown and an overview of the current baseline system design and its operation is presented. Assembly sequence of the ITCS is explained as its configuration develops from Man Tended Capability (MTC), for which node 2 alone is cooled, to Permanently Manned Capability (PMC) where the airlock, a pressurized logistics module, and node 1 are cooled, in addition to node 2. A SINDA/FLUINT math model of the ITCS is described, and results of analyses for an MTC and a PMC case are shown and discussed.

Merhoff, Paul↗
NASA NTRS1997

A SPDS Node to Support the Systematic Interpretation of Cosmic Ray Data

The purpose of this project was to establish and maintain a Space Physics Data System (SPDS) node that supports the analysis and interpretation of current and future galactic cosmic ray (GCR) measurements by (1) providing on-line databases relevant to GCR propagation studies; (2) providing other on-line services, such as anonymous FTP access, mail list service and pointers to e-mail address books, to support the cosmic ray community; (3) providing a mechanism for those in the community who might wish to submit similar contributions for public access; (4) maintaining the node to assure that the databases remain current; and (5) investigating other possibilities, such as CD-ROM, for public dissemination of the data products. Shortly after the original grant to support these activities was established at Louisiana State University a detailed study of alternate choices for the node hardware was initiated. The chosen hardware was an Apple Workgroup Server 9150/120 consisting of a 120 MHz PowerPC 601 processor, 32 MB of memory, two I GB disks and one 2 GB disk. This hardware was ordered and installed and has been operating reliably ever since. A preliminary version of the database server was available during the first year effort and was used as part of the very successful SPDS demonstration during the Rome, Italy International Cosmic Ray Conference. For this server version we were able to establish the html and anonymous FTP server software, develop a Web page structure which can be easily modified to include new items, provide an on-line database of charge changing total cross sections, include the cross section prediction software of Silberberg & Tsao as well as Webber, Kish and Schrier for download access, and provide an on-line bibliography of the cross section measurement references by the Transport Collaboration. The preliminary version of this SPDS Cosmic Ray node was examined by members of the C&H SPDS committee and returned comments were used to refine the implementation.

Source record↗
NASA NTRS1998

A Novel Four-Node Quadrilateral Smoothing Element for Stress Enhancement and Error Estimation

A four-node, quadrilateral smoothing element is developed based upon a penalized-discrete-least-squares variational formulation. The smoothing methodology recovers C1-continuous stresses, thus enabling effective a posteriori error estimation and automatic adaptive mesh refinement. The element formulation is originated with a five-node macro-element configuration consisting of four triangular anisoparametric smoothing elements in a cross-diagonal pattern. This element pattern enables a convenient closed-form solution for the degrees of freedom of the interior node, resulting from enforcing explicitly a set of natural edge-wise penalty constraints. The degree-of-freedom reduction scheme leads to a very efficient formulation of a four-node quadrilateral smoothing element without any compromise in robustness and accuracy of the smoothing analysis. The application examples include stress recovery and error estimation in adaptive mesh refinement solutions for an elasticity problem and an aerospace structural component.

Tessler, A.↗
NASA NTRS2004

International Space Station (ISS) Node 1 Environmental Control and Life Support (ECLS) System Keep Out Zone On-Orbit Problems

The International Space Station (ISS) Environmental Control and Life Support (ECLS) system performance can be impacted by operations on ISS. This is especially important for the Temperature and Humidity Control (THC) and for the Fire Detection and Suppression (FDS) subsystems. It is also more important for Node 1 since it has become a convenient area for many crew tasks and for stowing hardware prior to Shuttle arrival. This paper will discuss the current requirements for ECLS keep out zones in Node 1; the issues with stowage in Node 1 during Increment 7 and how they impacted the keep out zone requirements; and the solution during Increment 7 and 8 for maintaining the keep out zones in Node 1.

Williams, David E.↗
NASA NTRS2008

International Space Station Environmental Control and Life Support Emergency Response Verification for Node 1

The International Space Station (ISS) Node 1 Environmental Control and Life Support (ECLS) System is comprised of five subsystems: Atmosphere Control and Supply (ACS), Atmosphere Revitalization (AR), Fire Detection and Suppression (FDS), Temperature and Humidity Control (THC), and Water Recovery and Management (WRM). This paper provides a summary of the Node 1 Emergency Response capability, which includes nominal and off-nominal FDS operation, off nominal ACS operation, and off-nominal THC operation. These subsystems provide the capability to help aid the crew members during an emergency cabin depressurization, a toxic spill, or a fire. The paper will also provide a discussion of the detailed Node 1 ECLS Element Verification methodologies for operation of the Node 1 Emergency Response hardware operations utilized during the Qualification phase.

Williams, David E.↗
NASA NTRS2000

Managing Complexity - Developing the Node Control Software For The International Space Station

On December 4th, 1998 at 3:36 AM STS-88 (the space shuttle Endeavor) was launched with the "Node 1 Unity Module" in its payload bay. After working on the Space Station program for a very long time, that launch was one of the most beautiful sights I had ever seen! As the Shuttle proceeded to rendezvous with the Russian American module know as Zarya, I returned to Houston quickly to start monitoring the activation of the software I had spent the last 3 years working on. The FGB module (also known as "Zarya"), was grappled by the shuttle robotic arm, and connected to the Unity module. Crewmembers then hooked up the power and data connections between Zarya and Unity. On December 7th, 1998 at 9:49 PM CST the Node Control Software was activated. On December 15th, 1998, the Node-l/Zarya "cornerstone" of the International Space Station was left on-orbit. The Node Control Software (NCS) is the first software flown by NASA for the International Space Station (ISS). The ISS Program is considered the most complex international engineering effort ever undertaken. At last count some 18 countries are active partners in this global venture. NCS has performed all of its intended functions on orbit, over 200 miles above us. I'll be describing how we built the NCS software.

Wood, Donald B.↗
NASA NTRS2011

International Space Station Environmental Control and Life Support System Acceptance Testing for Node 1 Temperature and Humidity Control Subsystem

The International Space Station (ISS) Node 1 Environmental Control and Life Support (ECLS) System is comprised of five subsystems: Atmosphere Control and Storage (ACS), Atmosphere Revitalization (AR), Fire Detection and Suppression (FDS), Temperature and Humidity Control (THC), and Water Recovery and Management (WRM). This paper will provide a summary of the Node 1 ECLS THC subsystem design and a detailed discussion of the ISS ECLS Acceptance Testing methodology utilized for this subsystem.The International Space Station (ISS) Node 1 Environmental Control and Life Support (ECLS) System is comprised of five subsystems: Atmosphere Control and Storage (ACS), Atmosphere Revitalization (AR), Fire Detection and Suppression (FDS), Temperature and Humidity Control (THC), and Water Recovery and Management (WRM). This paper will provide a summary of the Node 1 ECLS THC subsystem design and a detailed discussion of the ISS ECLS Acceptance Testing methodology utilized for this subsystem.

Williams, David E.↗
NASA NTRS2015

Underwater Multi-Node Radio Communication Solutions for Planetary Exploration

The exploration of the presumably life harboring subsurface ocean of Europa will provide scientists with extensive new knowledge in the search for extraterrestrial life. A highly miniaturized payload is required to penetrate a narrow passage through the thick ice crust covering Europa's surface. Underwater wireless communications may be the most viable means of communication for such exploratory missions, accounting for size and weight restrictions. This presents a challenge to achieve satisfactory data rates and a range that permits autonomous underwater vehicles (AUVs) to communicate within their region of operation, as well as with a surface lander or orbiter. This work presents thorough prototype experimentation on an underwater communication system established between several nodes using RF signals. During an eight-week internship experience at NASA's Ames Research Center in September-October 2014, our team developed a Europa exploration mission concept, built representative hardware, and carried out tests to assess the feasibility of key aspects of the concept. Experiments demonstrating the viability of RF communication underwater comprised inspecting the effect of depth and horizontal distance on signal strength as well as the optimum positioning of antennas. To test the system's performance, two submersibles were designed and built. A commercially available remotely operated vehicle (ROV) was also modified and used as a main communication node. The two submersibles were wirelessly connected and accommodated sensors capable of characterizing water properties and equipped with 2.4 GHz, 1 mW transceivers to communicate the measured data. The communication procedure is that the main communication node requests the collected data from the two submersibles when in range and receives it instantly through RF. This work models what may take place during an actual mission to Europa. The developed mission concept involved a hybrid communication system consisting of acoustic and RF signals to enhance the capability of the nodes to communicate over greater distances. The AUVs will need to avoid obstacles and maneuver around to collect data based on predefined algorithms. Thus, they will be provided with two positioning systems; the inertial navigation system, backed with an acoustic positioning system to mitigate drift. The AUVs divide the ocean into planes and explore along circular paths increasing in diameter with depth. Moreover, they make use of miniaturized sensors to map the surrounding environment. In this paper, the ROV and the submersibles are described, along with sections explaining the mechanism of communication and the testing procedures conducted to yield results.

Europa↗
NASA NTRS2016

Method and Circuit for Injecting a Precise Amount of Charge onto a Circuit Node

A method and circuit for injecting charge into a circuit node, comprising (a) resetting a capacitor's voltage through a first transistor; (b) after the resetting, pre-charging the capacitor through the first transistor; and (c) after the pre-charging, further charging the capacitor through a second transistor, wherein the second transistor is connected between the capacitor and a circuit node, and the further charging draws charge through the second transistor from the circuit node, thereby injecting charge into the circuit node.

Hancock, Bruce R.↗
NASA NTRS1974

Quantized vortices around wavefunction nodes. II

The expectation of quantized vortices around the nodes of wavefunctions is formulated in terms of Schroedinger quantum mechanics, and the derivation is shown to depend only on the requirement that the wavefunction be single-valued and continuous. The implications of circulation for the topology of the nodes are discussed, and consideration is given to the nodes and circulation of a smooth wavefunction in D dimensions and to the significance of exceptional nodal points. The theoretical results are illustrated by an example of an infinite field of regularly spaced vortices.

Hirschfelder, J. O.↗
NASA NTRS1986

A Stirling engine analysis method based upon moving gas nodes

A Lagrangian nodal analysis method for Stirling engines (SEs) is described, validated, and applied to a conventional SE and an isothermalized SE (with fins in the hot and cold spaces). The analysis employs a constant-mass gas node (which moves with respect to the solid nodes during each time step) instead of the fixed gas nodes of Eulerian analysis. The isothermalized SE is found to have efficiency only slightly greater than that of a conventional SE.

Martini, W. R.↗
NASA NTRS1989

Strut-node joint conjugates for the assembly of semi-permanent or reusable truss structures

When strut and node components are used for truss construction an assembly problem occurs if a strut must be fitted between nodes whose separation distance is either closer or farther than the design intended. This condition is the result of normal dimensional variations that occur in any manufacturing process. In such circumstances two actions would permit continued assembly: change the effective strut length, and move the nodes. Assuming continued assembly is the most attractive alternative, attention is focused on accomplishing these actions as part of the assembly process.

Brewer, W. V.↗
NASA NTRS1989

20 kHz, 25 kVA node power transformer

The electrical and mechanical design information and the electrical and thermal testing performed on the 440-208-V rms, 20-kHz, 25-kVa prototype node transformer are summarized. The calculated efficiency of the node transformer is 99.3 percent based on core loss and copper loss test data, and its maximum calculated load regulation is 0.7 percent. The node transformer has a weight of 19.7 lb and has a power density of 0.8 lb/kW. The hot-spot temperature rise is estimated to be 33 C above the cold plate mounting base. This proof-of-concept transformer design is a viable candidate for the space station Freedom application.

Hussey, S.↗
NASA NTRS1990

Spaceport aurora: An orbiting transportation node

With recent announcements of the development of permanently staffed facilities on the Moon and Mars, the national space plan is in need of an infrastructure system for transportation and maintenance. A project team at the University of Houston College of Architecture and the Sasakawa International Center for Space Architecture, recently examined components for a low Earth orbit (LEO) transportation node that supports a lunar build-up scenario. Areas of investigation included identifying transportation node functions, identifying existing space systems and subsystems, analyzing variable orbits, determining logistics strategies for maintenance, and investigating assured crew return systems. The information resulted in a requirements definition document, from which the team then addressed conceptual designs for a LEO transportation node. The primary design drivers included: orbital stability, maximizing human performance and safety, vehicle maintainability, and modularity within existing space infrastructure. For orbital stability, the power tower configuration provides a gravity gradient stabilized facility and serves as the backbone for the various facility components. To maximize human performance, human comfort is stressed through zoning of living and working activities, maintaining a consistent local vertical orientation, providing crew interaction and viewing areas and providing crew return vehicles. Vehicle maintainability is accomplished through dual hangars, dual work cupolas, work modules, telerobotics and a fuel depot. Modularity is incorporated using Space Station Freedom module diameter, Space Station Freedom standard racks, and interchangeable interior partitions. It is intended that the final design be flexible and adaptable to provide a facility prototype that can service multiple mission profiles using modular space systems.

Source record↗
NASA NTRS1991

Space Station resource node flow field analysis

An analysis of the flow field within the Space Station Freedom resource node with operational intermodule ventilation and temperature/humidity control ventilation systems has been conducted. The INS3D code, an incompressible, steady-state Navier-Stokes solver has been used to assess the design of the ventilation system via quantification of the level of fluid mixing and identification of 'dead air' regions and short-circuit ventilation. Numerical results indicate significant short-circuit ventilation in the forward and midsections of the node and insufficient fluid mixing is found to exist in the aft node section. These results as well as results from a solution grid dependence study are presented.

Kania, Lee↗
NASA NTRS1992

An assessment of four-noded plate finite elements based on a generalized third-order theory

Plate finite elements based on the generalized third-order theory of Reddy and the first-order shear deformation theory are analyzed and compared on the basis of thick and thin plate modeling behavior, distortion sensitivity, overall accuracy, reliability, and efficiency. In particular, several four-noded Reddy-type elements and the nine-noded Lagrangian and heterosis (Mindlin-type) plate elements are analyzed to assess their behavior in bending, vibration, and stability of isotropic and laminated composite plates. A four-noded Reddy-type element is identified which is free of all spurious stiffness and zero energy modes, computationally efficient, and suitable for use in any general-purpose finite element program.

Averill, R. C.↗