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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 505 records · Page 28

High Power W-Band/F-Band Schottky Diode Based Frequency Multipliers

A solid state device chip including diodes (generating a higher frequency output through frequency multiplication of the input frequency) and a novel on-chip power combining design. Together with the on-chip power combining, the chip has increased efficiency because the diodes' anodes, being micro-fabricated simultaneously on the same patch of a GaAs wafer under identical conditions, are very well balanced. The diodes' GaAs heterostructure and the overall chip geometry are designed to be optimized for high power operation. As a result of all these features, the device can generate record-setting power having a signal frequency in the F-band and W-band (30% conversion efficiency).

Siles Perez, Jose Vicente↗

Asynchronous Ballistic Reversible Fluxon Logic

In a previous study, we described a new abstract circuit model for reversible computation called Asynchronous Ballistic Reversible Computing (ABRC), in which localized information bearing pulses propagate ballistically along signal paths between stateful abstract devices, and elastically scatter off those devices serially, while updating the device state in a logically-reversible and deterministic fashion. The ABRC model has been shown to be capable of universal computation. In the research reported here, we begin exploring how the ABRC model might be realized in practice using single flux quantum (SFQ) solitons (fluxons) in superconducting Josephson junction (JJ) circuits. One natural family of realizations could utilize fluxon polarity to represent binary data in individual pulses propagating near-ballistically along discrete or continuous long Josephson junctions (LJJs) or microstrip passive transmission lines (PTLs), and utilize the flux charge (-1, 0, +1) of a JJ-containing superconducting loop with Φ 0 < I c L < 2Φ 0 to encode a ternary state variable internal to a device. A natural question then arises as to which of the definable abstract ABRC device functionalities using this data representation might be implementable using a JJ circuit that dissipates only a small fraction of the input fluxon energy. We discuss conservation rules and symmetries considered as constraints to be obeyed in these circuits, and begin the process of classifying the possible ABRC devices in this family having up to 3 bidirectional I/O terminals, and up to 3 internal states.

97 MATHEMATICS AND COMPUTING↗

Comparison between 1.7 kV SiC SJT and MOSFET Power Modules

Abstract— In this paper, a comprehensive evaluation work on 1.7 kV SiC Super Junction Transistor (SJT) power module and 1.7 kV SiC MOSFET power modules is presented. Both device static and dynamic performance is extracted and compared at wide device current range and temperature range. The data presented in this paper can be used as input for medium voltage power conversion system power transistor selection, gate drive design and system level thermal management design. Since the SiC SJT is a new power transistor with unique current driven mechanism. A dedicated section discusses the SiC SJT power module gate drive configuration and device false turn on suppress as well. In a summary, 1.7 kV SiC SJT shows superior on state conductivity, but similar switching performance compared to 1.7 kV SiC MOSFET power modules.

gate drive↗

Modular protein-oligonucleotide signal exchange

Abstract While many methods are available to measure the concentrations of proteins in solution, the development of a method to quantitatively report both increases and decreases in different protein concentrations in real-time using changes in the concentrations of other molecules, such as DNA outputs, has remained a challenge. Here, we present a biomolecular reaction process that reports the concentration of an input protein in situ as the concentration of an output DNA oligonucleotide strand. This method uses DNA oligonucleotide aptamers that bind either to a specific protein selectively or to a complementary DNA oligonucleotide reversibly using toehold-mediated DNA strand-displacement. It is possible to choose the sequence of output strand almost independent of the sensing protein. Using this strategy, we implemented four different exchange processes to report the concentrations of clinically relevant human α-thrombin and vascular endothelial growth factor using changes in concentrations of DNA oligonucleotide outputs. These exchange processes can operate in tandem such that the same or different output signals can indicate changes in concentration of distinct or identical input proteins. The simplicity of our approach suggests a pathway to build devices that can direct diverse output responses in response to changes in concentrations of specific proteins.

59 BASIC BIOLOGICAL SCIENCES↗

Interference of Spin Waves in Arrays of Microwaveguides Based on Yttrium-Iron Garnet Films

Effects of propagation and interference of spin waves in an eight-port magnonic structure in the form of a 2 × 2 array of microwaveguides based on yttrium-iron garnet films with microantennas placed at the waveguide ends are studied experimentally and numerically. It is shown that conditions for a constructive and destructive interference of spin waves, which is necessary for creating spin-wave logic devices, can be implemented at output transducers by changing the phase of input signals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

GEECS (Generalized Equipment and Experiment Control System)

GEECS (Generalized Equipment and Experiment Control System) monitors and controls equipment distributed across a network, performs experiments by scanning input variables, and collects and stores various types of data synchronously from devices. Examples of devices include cameras, motors and pressure gauges. GEEKS is based upon LabView graphical object oriented programming (GOOP), allowing for a modular and scalable framework. Data is published for subscription of an arbitrary number of variables over TCP. A secondary framework allows easy development of graphical user interfaces for a combined control of any available devices on the control system without the need of programming knowledge. This allows for rapid integration of GEECS into a wide variety of systems. A database interface provides for devise and process configuration while allowing the user to save large quantities of data to local or network drives.

Gonsalves, Anthony↗

Finite element modeling of nanoscale-enabled microinductors for power electronics

Here, this paper focuses on the finite element modeling of toroidal microinductors, employing first-of-its-kind nanocomposite magnetic core material and superparamagnetic iron nanoparticles covalently cross-linked in an epoxy network. Energy loss mechanisms in existing inductor core materials are covered as well as discussions on how this novel core material eliminates them providing a path toward realizing these low form factor devices. Designs for both a 2 μH output and a 500 nH input microinductor are created via the model for a high-performance buck converter. Both modeled inductors have 50 wire turns, less than 1 cm 3 form factors, less than 1 Ω AC resistance, and quality factors, Q’s, of 27 at 1 MHz. In addition, the output microinductor is calculated to have an average output power of 7 W and a power density of 3.9 kW/in 3 by modeling with the 1st generation iron nanocomposite core material.

36 MATERIALS SCIENCE↗

Bench Testing Results for the Electrical PCM-Assisted Thermal Heating System (ePATHS)

Bench testing of the Electrical PCM-Assisted Thermal Heating System (ePATHS) was completed at the Building Technologies Research and Integration Center (BTRIC) at the Oak Ridge National Laboratory (ORNL). The ePATHS is a thermal energy storage device designed to reduce the energy required from the battery for cabin heating of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs). ORNL s testing of the ePATHS assessed three main aspects of operation of the device: 1.ePATHS charging evaluation: measure the time to charge and the energy input needed to fully charge the PCM for a range of different ambient conditions. 2.ePATHS Discharge Evaluations: measure the energy provided by the PCM HX, both during mode 1 and mode 2 operation, and confirm the cabin heating duration that can be provided by the ePATHS. This is the primary evaluation to validate the system performance, and an array of multiple ambient conditions and operating scenarios were tested. 3.Evaluation of Thermal Losses from the ePATHS during Cold Soak: this test will evaluate the performance of the insulation system for the ePATHS. The charged ePATHS undergoes a long-term soak in cold ambient temperature conditions, and the heat losses will be evaluated to validate that the performance meets the maximum energy loss requirement.

33 ADVANCED PROPULSION SYSTEMS↗

Real-Time Operating System/360

RTOS has a cost savings advantage for real-time applications, such as those with random inputs requiring a flexible data routing facility, display systems simplified by a device independent interface language, and complex applications needing added storage protection and data queuing.

Hoffman, R. L.↗

Techniques associated with thermal-vacuum testing of the OAO-C heat pipes

The mechanical problems associated with testing the two high-heat load pipes are discussed. One of these pipes was tested three times before being accepted. The first test resulted in the discovery of non-condensable hydrogen gas, which prevented the pipe from functioning properly. The second test was a repeat of the first, to see if all the gas had been removed. The third test was to see if any changes had occurred to the pipe as a result of saddle modifications. Saddle modifications were necessary because the epoxy binding agent between the saddles and the pipe had decomposed during the testing. The test problems discussed deal with the specially designed heat-removal devices, the mobile tilt table, the table position indicator, and the heat input mechanisms, all of which were necessary to conduct a high-heat load, thermal-vacuum test. The final results showed that the techniques used were adequate for thermal-vacuum testing of heat pipes.

Marshburn, J. P.↗

Techniques associated with thermal-vacuum testing of the OAO C heat pipes

The mechanical problems associated with the testing of two heat pipes installed in the OAO C spacecraft are described. The test problems discussed concern the specially designed heat removal devices, the mobile tilt table, the table position indicator, and the heat input machanisms. It was determined that the techniques used were adequate for thermal-vacuum testing of heat pipes.

Marshburn, J. P.↗

Derivation of a tangent function using an integrated circuit four-quadrant multiplier

A tangent function generator is provided which utilizes input signals proportionate to the sine and cosine of a given angle. The equipment accomplishes a trigonometric manipulation which forms an output signal substantially independent of the input reference voltage but proportional to the tangent of the angle. The device uses a multiplier and operational amplifier.

Bregman, B. J.↗

Tests and evaluation of multihundred watt thermoelectric generators at JPL

The multihundred watt (MHW) thermoelectric generator, based on silicon-germanium thermoelectric technology, delivers a nominal power output of 150 watts with an efficiency of about 6%. The two Voyager space probes each use three such generators assembled in tandem on a boom. A total of seven MHW type thermoelectric generators were tested at JPL in support of the Voyager project. The tests consisted of: (1) parametric evaluation of the electrical characteristics of the devices over a wide range of output voltage for different values of input power, different operating ambients (air, vacuum), and different internal environments (argon, helium, xenon, mixture of these gases, and vacuum) at different pressures to allow evaluation of the influences of both gas and pressure on the performance of the generator; (2) tests to determine the transient behavior of the generators; and (3) operation of the generator in conjunction with the Voyager spacecraft.

Rouklove, P.↗

An interactive computer program for sizing spacecraft momentum storage devices

An interactive computer program was developed which computes the sizing requirements for nongimbled reaction wheels, control moment gyros (CMG), and dual momentum control devices (DMCD) used in Earth-orbiting spacecraft. The program accepts as inputs the spacecraft's environmental disturbance torques, rotational inertias, maneuver rates, and orbital data. From these inputs, wheel weights are calculated for a range of radii and rotational speeds. The shape of the momentum wheel may be chosen to be either a hoop, solid cylinder, or annular cylinder. The program provides graphic output illustrating the trade-off potential between the weight, radius, and wheel speed. A number of the intermediate calculations such as the X-, Y-, and Z-axis total momentum, the momentum absorption requirements for reaction wheels, CMG's, DMCD's, and basic orbit analysis information are also provided as program output.

Wilcox, F. J., Jr.↗

A method for non-contact drop charge measurement

A new approach for detecting point type of charge has been developed. This system is based on the principle of reciprocal motion of a grounded conductor near a point charge. The current induced through such a process can then be used to determine the static field strength of the point charge, hence the quantity of the charge. Experiments were done to understand the characteristics of this new device. Test case indicates that the results are in good agreement with the theoretical prediction. This device shows extremely good linearity with respect to the strength of the input static field. The resolution of the system is better than 10 V/m, which is about two orders of magnitude in sensitivity higher than other types of field measuring apparatus. The high sensitivity of this system makes it possible to conduct charged drop experiments under microgravity conditions.

Lin, K. C.↗

Photon detection with parallel asynchronous processing

An approach to photon detection with a parallel asynchronous signal processor is described. The visible or IR photon-detection capability of the silicon p(+)-n-n(+) detectors and the parallel asynchronous processing are addressed separately. This approach would permit an independent analog processing channel to be dedicated to every pixel. A laminar architecture consisting of a stack of planar arrays of the devices would form a 2D array processor with a 2D array of inputs located directly behind a focal-plane detector array. A 2D image data stream would propagate in neuronlike asynchronous pulse-coded form through the laminar processor. Such systems can integrate image acquisition and image processing. Acquisition and processing would be performed concurrently as in natural vision systems. The possibility of multispectral image processing is addressed.

Coon, D. D.↗

Computerized atmospheric trace contaminant control simulation for manned spacecraft

Buildup of atmospheric trace contaminants in enclosed volumes such as a spacecraft may lead to potentially serious health problems for the crew members. For this reason, active control methods must be implemented to minimize the concentration of atmospheric contaminants to levels that are considered safe for prolonged, continuous exposure. Designing hardware to accomplish this has traditionally required extensive testing to characterize and select appropriate control technologies. Data collected since the Apollo project can now be used in a computerized performance simulation to predict the performance and life of contamination control hardware to allow for initial technology screening, performance prediction, and operations and contingency studies to determine the most suitable hardware approach before specific design and testing activities begin. The program, written in FORTRAN 77, provides contaminant removal rate, total mass removed, and per pass efficiency for each control device for discrete time intervals. In addition, projected cabin concentration is provided. Input and output data are manipulated using commercial spreadsheet and data graphing software. These results can then be used in analyzing hardware design parameters such as sizing and flow rate, overall process performance and program economics. Test performance may also be predicted to aid test design.

Perry, J. L.↗

Growth of thin films of organic nonlinear optical materials by vapor growth processes - An overview and examination of shortfalls

Research on the growth of second- and third-order nonlinear optical (NLO) organic thin film by vapor deposition is reviewed. Particular attention is given to the experimental methods for growing thin films of p-chlorophenylurea, diacetylenes, and phthalocyanines; characteristics of the resulting films; and approaches for advancing thin film technology. It is concluded that the growth of NLO thin films by vapor processes is a promising method for the fabrication of planar waveguides for nonlinear optical devices. Two innovative approaches are proposed including a method of controlling the input beam frequency to maximize nonlinear effects in thin films and single crystals, and the alternate approach to the molecular design of organic NLO materials by increasing the transition dipole moment between ground and excited states of the molecule.

Frazier, D. O.↗