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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Development of a Liquid Bridge Model for Particle Agglomeration and Defluidization in Plastic Pyrolysis

Molten plastic that forms during the pyrolysis of plastic or municipal solid waste feedstock can lead to particle agglomeration. A liquid bridge model is developed in MFiX-DEM and validated against a cold flow experiment with glass beads coated with silicone oil. The liquid bridge model is then extended to support an evolving liquid layer thickness for pyrolysis applications. The extended model is used to study the sensitivity of the pyrolysis reactor to solids holdup, flow conditions, and plastic properties.

Banerjee, Subhodeep↗
DOE OSTI2025

Bridging multimodal microscopy for advanced characterization on nuclear fuel using machine learning

Uranium dioxide (UO 2 ), widely used as driver fuel in light water reactors, experiences microstructure and property change by nuclear fission reactions. This paper bridges the characterization of fresh UO 2 fuel at different length scales, serving as a baseline for future post irradiation examination of irradiated UO 2 fuel. To characterize the microstructural change of nuclear fuel, modern approaches cover a wide range of length scales through different characterization techniques, such as mm scale for Synchrotron-based X-ray computed tomography (SXCT) and microscale for focused ion beam (FIB) and scanning electron microscopy (SEM). It is challenging to bridge the data and knowledge of the same sample in different length scales. This paper proposed a deep learning framework leveraging transfer learning to detect microstructural defects, trained from a sparse FIB, SEM, and SXCT images. The proposed model achieved superior performance in defect segmentation on multiscale microscopic data compared to four of the latest deep learning models.

36 MATERIALS SCIENCE↗
NASA NTRS1968

Precision bolometer bridge

Prototype precision bolometer calibration bridge is manually balanced device for indicating dc bias and balance with either dc or ac power. An external galvanometer is used with the bridge for null indication, and the circuitry monitors voltage and current simultaneously without adapters in testing 100 and 200 ohm thin film bolometers.

White, D. R.↗
NASA NTRS1969

Ratio matching of half-bridge weldable strain gages, computer program

Computer program reduces the unbalance of weldable half-bridge strain gage installations. The program calculates the two resistance ratios of each half-bridge gage, outputting a table of gages ranked according to resistance ratio. The tabulation forms a convenient record of gage characteristics.

Anderson, K. F.↗
NASA NTRS1972

Diode-quad bridge for reactive transducers and FM discriminators

Diode-quad bridge circuit was developed for use with pressure-sensitive capacitive transducers, liquid-level measuring devices, proximity deflection sensors, and inductive displacement sensors. It may also be used as FM discriminator and as universal impedance bridge.

Harrison, D. R.↗
NASA NTRS1973

Temperature control system with a pulse width modulated bridge

A temperature control system, which includes a modified wheatstone bridge with a resistive-capacitive (RC) circuit in one leg of the bridge, is disclosed. The RC circuit includes a resistor which provides an effective resistance as a function of its absolute resistance and the on-time to off-time ratio of pulses supplied to a switch connected across it. A sawtooth voltage is produced across the RC circuit. The voltage is compared with the voltage across a temperature sensor with heat being applied during each pulse period portion when the sawtooth voltage exceeds the voltage across the temperature sensor.

Heyser, R. C.↗
NASA NTRS1973

Dynamic analysis of a long span, cable-stayed freeway bridge using NASTRAN

The dynamic analysis for earthquake- and wind-induced response of a long span, cable-stayed freeway bridge by NASTRAN in conjunction with post-processors is described. Details of the structural modeling, the input data generation, and numerical results are given. The influence of the dynamic analysis on the bridge design is traced from the project initiation to the development of a successful earthquake and wind resistant configuration.

Salus, W. L.↗
NASA NTRS1975

Strain-gage bridge calibration and flight loads measurements on a low-aspect-ratio thin wing

Strain-gage bridges were used to make in-flight measurements of bending moment, shear, and torque loads on a low-aspect-ratio, thin, swept wing having a full depth honeycomb sandwich type structure. Standard regression analysis techniques were employed in the calibration of the strain bridges. Comparison of the measured loads with theoretical loads are included.

Peele, E. L.↗
NASA NTRS1976

Flight loads measurements obtained from calibrated strain-gage bridges mounted externally on the skin of a low-aspect-ratio wing

Flight-test measurements of wingloads (shear, bending moment, and torque) were obtained by means of strain-gage bridges mounted on the exterior surface of a low-aspect-ratio, thin, swept wing which had a structural skin, full-depth honeycomb core, sandwich construction. Details concerning the strain-gage bridges, the calibration procedures used, and the flight-test results are presented along with some pressure measurements and theoretical calculations for comparison purposes.

Eckstrom, C. V.↗
NASA NTRS1976

Germanium-overcoated niobium Dayem bridges

Overcoating constriction microbridges with semiconducting germanium provides additional thermal conductivity at liquid-helium temperatures to reduce the effects of self-heating in these Josephson junctions. Microwave-induced steps were observed in the I-V characteristics of an overcoated Dayem bridge fabricated in a 15-nm-thick niobium film; at least 20 steps could be counted at 4.2 K. No steps were observed in the I-V characteristics of the bridge prior to overcoating. In addition, the germanium overcoat can protect against electrical disturbances at room temperature.

Holdeman, L. B.↗
NASA NTRS1984

Convective thermocapillary instabilities in liquid bridges

A steady shear flow is generated in an axisymmetric liquid bridge surrounded by a passive gas through the imposition of a temperature gradient along the bridge and the driving of the motion by thermocapillarity. This dynamic state is susceptible to convective instabilities, which can lead to propagating hydrothermal waves that feed on the underlying temperature gradients. The convective instabilities of axisymmetric return flow are presently given as functions of the liquid's Prandtl number and the surface Biot number of the interface.

Xu, J.-J.↗
NASA NTRS1985

Split-cross-bridge resistor for testing for proper fabrication of integrated circuits

An electrical testing structure and method is described whereby a test structure is fabricated on a large scale integrated circuit wafer along with the circuit components and has a van der Pauw cross resistor in conjunction with a bridge resistor and a split bridge resistor, the latter having two channels each a line width wide, corresponding to the line width of the wafer circuit components, and with the two channels separated by a space equal to the line spacing of the wafer circuit components. The testing structure has associated voltage and current contact pads arranged in a two by four array for conveniently passing currents through the test structure and measuring voltages at appropriate points to calculate the sheet resistance, line width, line spacing, and line pitch of the circuit components on the wafer electrically.

Buehler, M. G.↗
NASA NTRS1986

Loads calibrations of strain gage bridges on the DAST project Aeroelastic Research Wing (ARW-2)

Results from and details of the procedure used to calibrate strain gage bridges for measurements of wing structural loads, shear (V), bending moment (M), and torque (T), at three semispan stations on both the left and right semispans of the ARW-2 wing are presented. The ARW-2 wing has a reference area of 35 square feet, a span of 19 feet, an aspect ratio of 10.3, a midchord line sweepback angle of 25 degrees, and a taper ratio of 0.4. The ARW-2 wing was fabricated using aluminum spars and ribs covered with a fiberglass/honeycomb sandwich skin material. All strain gage bridges are mounted along with an estimate of their accuracy by means of a comparison of computed loads versus actual loads for three simulated flight conditions.

Eckstrom, C. V.↗
NASA NTRS1987

Design and implementation of the ESL compact range underhung bridge crane

As the indoor compact range technology has continued to increase, the need to handle larger and heavier targets has also increased. This need for target lifting and handling prompted the feasibility study of the use of an underhung bridge crane to be installed in the ESL (ElectroScience Laboratory, Ohio State University) compact range. This report documents both the design of the underhung bridge crane that was installed and the implementation of the design in the actual installation of the crane.

Shamansky, H. T.↗
NASA NTRS1990

Balanced bridge feedback control system

In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.

Lurie, Boris J.↗
NASA NTRS1991

Longitudinal splitting in epoxy and K-polymer composites - Shear lag analysis including the effect of fiber bridging

The shear-lag model used previously by Nairn (1988) to derive a fracture mechanics analysis of longitudinal splitting in double-edge notched unidirectional composites was used to investigate the effect of fibers bridging across the longitudinal split in these composites. Using the new analysis, the longitudinal splitting fracture toughness, G(Lc), was determined for Hercules AS4/3501-6 graphite/epoxy laminates and for K-polymer based laminates containing Magnamite IM-6 as the graphite reinforcing fiber. Results show that the inclusion of the fiber bridging in the fracture analysis significantly affects the reported fracture toughness.

Nairn, John A.↗
NASA NTRS1992

Surface tension and buoyancy-driven flow in a non-isothermal liquid bridge

The Navier-Stokes-Boussinesq equations governing the transport of momentum, mass and heat in a nonisothermal liquid bridge with a temperature-dependent surface tension are solved using a vorticity-stream-function formulation together with a nonorthogonal coordinate transformation. The equations are discretized using a pseudo-unsteady semi-implicit finite difference scheme and are solved by the ADI method. A Picard-type iteration is adopted which consists of inner and outer iterative processes. The outer iteration is used to update the shape of the free surface. Two schemes have been used for the outer iteration; both use the force balance normal to the free surface as the distinguished boundary condition. The first scheme involves successive approximation by the direct solution of the distinguished boundary condition. The second scheme uses the artificial force imbalance between the fluid pressure, viscous and capillary forces at the free surface which arises when the boundary condition for force balance normal to the surface is not satisfied. This artificial imbalance is then used to change the surface shape until the distinguished boundary condition is satisfied. These schemes have been used to examine a variety of model liquid bridge situations including purely thermocapillary-driven flow situations and mixed thermocapillary- and bouyancy-driven flow.

Zhang, Yiqiang↗