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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Development of technologies for welding interconnects to fifty-micron thick silicon solar cells

A program was conducted to develop technologies for welding interconnects to 50 microns thick, 2 by 2 cm solar cells. The cells were characterized with respect to electrical performance, cell thickness, silver contact thickness, contact waviness, bowing, and fracture strength. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Thermal shock tests (100 cycles from 100 C to -180 C) were performed on 16 cell coupons for each cell type without any weld joint failures or electrical degradation. Three 48 cell modules (one for each cell type) were assembled with 50 microns thick cells, frosted fused silica covers, silver clad Invar interconnectors, and Kapton substrates.

Patterson, R. E.↗
NASA NTRS1983

Manipulator interactive design with interconnected flexible elements

This paper describes the development of an analysis tool for the interactive design of control systems for manipulators and similar electro-mechanical systems amenable to representation as structures in a topological chain. The chain consists of a series of elastic bodies subject to small deformations and arbitrary displacements. The bodies are connected by hinges which permit kinematic constraints, control, or relative motion with six degrees of freedom. The equations of motion for the chain configuration are derived via Kane's method, extended for application to interconnected flexible bodies with time-varying boundary conditions. A corresponding set of modal coordinates has been selected. The motion equations are imbedded within a simulation that transforms the vector-dyadic equations into scalar form for numerical integration. The simulation also includes a linear, time-invariant controler specified in transfer function format and a set of sensors and actuators that interface between the structure and controller. The simulation is driven by an interactive set-up program resulting in an easy-to-use analysis tool.

Singh, R. P.↗
NASA NTRS1983

Welding interconnects to 50-micron silicon solar cells

A program was conducted to develop technologies for welding interconnects to 50-micron thick, 2 by 2 cm solar cells obtained from three suppliers. The cells were characterized with respect to electrical performance, cell thickness, silver contact thickness, contact waviness, bowing, and fracture strength. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Thermal shock tests (100 cycles from 100 deg to -180 deg C) were performed on 16-cell coupons for each cell type without any weld joint failures or electrical degradation. Three 48-cell modules (one for each cell type) were assembled with 50-micron thick cells, frosted fused silica covers, silver clad Invar interconnectors, and Kapton substrates.

Patterson, R. E.↗
NASA NTRS1985

Vector Lyapunov Functions for Stochastic Interconnected Systems

Theoretical paper presents set of sufficient conditions for asymptotic and exponential stability with probability 1 for class of stochastic interconnected systems. Theory applicable to complicated, large-scale mechanical or electrical systems, and, for several design problems, it reduces computational difficulty by relating stability criteria to fundamental structural features of system.

Boussalis, D.↗
NASA NTRS1984

Stuttgart Interconnection Network Project from PIX to NICS

The PIX follow-up project NICS is described. The purpose of PIX was access to X.25, the DATEX-P network of the Federal German Post Office. The development and implementation of higher protocols for levels 4-7 in the ISOSINN was the actual problem here. Results of the PIX project are given. NICS (Stuttgart Interconnection Network Project) is presented. International Protocols are reviewed. PAD service is described, which allows terminal access to DATEX-P network of the Federal German Post Office.

Source record↗
NASA NTRS1985

On the Interconnection of Incompatible Solid Finite Element Meshes Using Multipoint Constraints

Incompatible meshes, i.e., meshes that physically must have a common boundary, but do not necessarily have coincident grid points, can arise in the course of a finite element analysis. For example, two substructures may have been developed at different times for different purposes and it becomes necessary to interconnect the two models. A technique that uses only multipoint constraints, i.e., MPC cards (or MPCS cards in substructuring), is presented. Since the method uses only MPC's, the procedure may apply at any stage in an analysis; no prior planning or special data is necessary.

Fox, G. L.↗
NASA NTRS1985

Demonstrated results of welded and soldered interconnections

Solar cell modules with welded and soldered interconnections were constructed using a flexible substrate material. These modules were thermally cycled between approx. 80 deg C at rates 100 cycles/day to demonstrate survivability under simulated low Earth orbit (LEO) temperature conditions. The modules, cycled in an inert atmosphere, show durability for 36,000 cycles.

Hart, R. E., Jr.↗
NASA NTRS1985

Selective broadcast interconnection - A novel scheme for fiber-optic local-area networks

A passive, unswitched scheme is introduced for directly interconnecting N stations, each of which has C transmitters and receivers. Implementations using fiber optics with spatial multiplexing and optionally wavelength multiplexing are discussed. This scheme utilizes the same resources as standard topologies with C parallel buses but outperforms them in two respects: (1) the aggregate throughput is proportional to C squared rather than to C; and (2) the power of each transmitter need reach only N/C, instead of N, receivers.

Marhic, M. E.↗
NASA NTRS1986

Global interconnectivity in the next two decades - A scenario

The present paper provides a description of a part of NASA's current long range plans, taking into account the development of hierarchal space switching centers and laser intersatellite links which can interconnect the globe. It is pointed out that a special objective involves the development of technology and satellite architecture for reducing the cost of an end-to-end voice message per minute from the present average value of around $.40 now realized by terrestrial telephone systems to less than $.10. The next decade of NASA communications activity (1985-1995) is discussed, giving attention to the Advanced Communications Technology Satellite ACTS (July 1984) which will test the technology of space switchboard and signal processing in space. The environment of the decade 1985-1995 is considered along with the roles of communications satellites, the hierarchies of terrestrial public switched networks, cost comparisons of terrestrial and space point-to-point links, and concomitant technology developments related to supercomputers.

Lovell, R.↗
NASA NTRS1985

NASA's communications programs for interconnectivity

The U.S. 'bent pipe' satellites will be joined in 1989 by the NASA ACTS satellite. The present paper provides a status report on the ACTS satellite program. The ACTS satellite and the mobile satellite systems will conduct flight tests with respect to onboard switching for both wide band and narrow band communications. The ACTS program, with the laser link, and the mobile satellite programs with the large antennas will contribute to the test of four new technologies. Attention is given to the ACTS communication systems, the ACTS spacecraft characteristics, the ACTS modes of operation, RF technologies, interconnectivity technologies, and large antenna technologies.

Lovell, R. R.↗
NASA NTRS1986

Holographic optical interconnects for VLSI

This paper introduces new applications and design trade-offs anticipated for free-space optical interconnections of VLSI chips. New implementation s of VLSI functions are described that use the capability of making optical inputs at any point on a chip and take advantage of greater flexibility in on-chip signal routing. These include n-port addressable memories, CPU clock phase distribution, hardware multipliers, and dynamic memory refresh, as well as enhanced testability. Fault tolerance and production yields may be improved by reprogramming the optical imaging system to circumvent defective elements. These attributes, as well as those related to performance alone, will affect the design methodology of future VLSI ICs. This paper focuses on identifying the design issues, their possible solutions, and their impact on VLSI design techniques and, finally, presents some preliminary measurements on various system components.

Bergman, L. A.↗
NASA NTRS1987

A survey and comparison of fault-tolerant multistage interconnection networks

Intrinsically fault-tolerant multistage interconnection networks (MINs) are surveyed, categorizing the MINs by the amount of hardware modifications they use to provide redundancy. The diversity of such MINs and the scope of fault-tolerance techniques are examined. A hypothetical MIN with ideal engineering characteristics is defined, and the surveyed MINs are compared to this standard.

Adams, George B., III↗
NASA NTRS1987

On the interconnection of dynamic processes in the lower thermosphere with meteorological phenomena in the tropostratosphere

Nowadays the atmosphere is considered a single dynamic system governed by inner and other factors, the separate layers (troposphere, strato-mesosphere, thermosphere) of which are in a state of interaction though they differ physically from one another in thermal stratification and energetic processes. Observational data of thermodynamic parameter connections in these layers height range are presented. The interconnection between the temperature field disturbances in the tropo-stratosphere and the dynamic regime in the lower thermosphere in winter and summer is defined as revealed by observational data.

Fakhrutdinova, A. N.↗
NASA NTRS1987

CMOS detector cells for holographic optical interconnects in microcircuits

This paper reports on the characterization of CMOS detectors for holographic optical interconnects in micro circuits. A VLSI temporal response system has been built, which has high-magnification viewing capabilities to facilitate the identification of the sample area under investigation. An isolated photodiode and load circuit has been characterized to determine responsivity, response time, and light spot positioning effects. The threshold of optical gate cells incorporating the above detectors and a transistor inverter stage to couple to other circuitry has been determined. The rise time and fall time of the optical gate cells have also been determined experimentally. The results were compared with the results of SPICE simulation, and show satisfactory agreement. The time delay of optical gate cell output was thus determined to be 70 ns at 10 microW light input. Threshold power was 0.5 microW light input.

Wu, W. H.↗
NASA NTRS1989

Healing Voids In Interconnections In Integrated Circuits

Unusual heat treatment heals voids in aluminum interconnections on integrated circuits (IC's). Treatment consists of heating IC to temperature between 200 degrees C and 400 degrees C, holding it at that temperature, and then plunging IC immediately into liquid nitrogen. Typical holding time at evaluated temperature is 30 minutes.

Cuddihy, Edward F.↗
NASA NTRS1988

Optical Backplane Interconnect Technology (OBIT)

We describe and analyze a novel approach to implementing an Optical Backplane Interconnect Technology (OBIT) that is capable of optically connecting any row of a 32x32 backplane array to any row of a second 32x32 array. Each backplane array is formed monolithically on a wafer. The technology is based on the use of Grating Surface Emitting (GSE) waveguides formed on a wafer containing quantum-well and separate confinement waveguide layers. These layers are used for transverse guiding, gain, modulation, detection, and for the formation of wavelength tunable distributed-Bragg reflector lasers. The required surface structures are formed photolithographically. The GSE waveguides act as efficient antennae that radiate light at angles selected by tuning the wavelength of the lasers. The same waveguides may be used as the receiving antennae when the array is used in the receiving mode. Thus, wavelength tuning is used to direct each row of the transmitting array to the desired row of the receiving array. In summary: The optical backplane array will have the following characteristics: Any row of a 32x32 GSE array may be optically connected to any row of a second 32x32 array. Only one switch decision is required to switch 32 parallel connections to any one of 32 positions. Each monolithic array can be used as both transmitter and receiver by switching the bias on the quantum-well switch-detectors. Separate transmitting and receiving structures could be provided for duplex operation. For a bit error rate of 10 sup 9 at 100-MHz data rate, a required laser power of 12 mW is calculated based on an estimated total optical loss of 40 dB.

Hammer, J. M.↗
NASA NTRS1988

Model reduction in the simulation of interconnected flexible bodies

Given the control system specifications for a system of interconnected rigid and flexible bodies, methods now exist for determining the system modes that do not interact 'strongly' with the controller. Once these important system modes are known, there still remains the problem of determining the modes of individual bodies that should be retained, since, in the final analysis, it is the modal information at the component level that must be fed into any multibody simulation code. Systematic identification of these component modes is achieved through a two-phase matrix diagonalization process starting with judiciously chosen submatrices of the system modal matrix.

Eke, Fidelis O.↗
NASA NTRS1988

Optical interconnection techniques for Hypercube

Direct free-space optical interconnection techniques are described for the Hypercube concurrent processor machine using a holographic optical element. Computational requirements and optical constraints on implementation are briefly summarized with regard to topology, power consumption, and available technologies. A hybrid lens/HOE approach is described that can support an eight-dimensional cube of 256 nodes.

Johnston, A. R.↗