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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Characterizing Interference in a Wave-Powered Buoy

Oceanographic measurement buoys are power constrained by the capacity of their batteries and the available solar power. Many buoys are in locations with abundant wave energy, but wave energy converters are not being used to power them. One reason wave energy converters may not have not been developed for wave measurement buoys is that many buoys measure waves by precisely following the wave motion. Wave energy converters may inhibit this wave-following ability by altering a buoy's response to incoming waves. In this report, we present the results of field tests that measured the extent to which buoy motion was changed by modifications to the buoy for wave energy harvesting. The motion of the buoy was significantly modified by the addition of the hardware components necessary for harvesting wave energy. The ratio of the mass of the wave energy converter to the mass of the buoy was high for the system tested, which strongly affected buoy motion. A lower value for this ratio would decrease the effect of the wave energy converter on the motion of the buoy, thereby decreasing the impact on the buoy's ability to measure waves but also decreasing the power production capabilities. Therefore, the use of wave energy converters to power wave measurement buoys may be feasible for large buoys that measure low-frequency waves and have low power requirements.

16 TIDAL AND WAVE POWER↗
DOE OSTI2024

Unconventional Wells Interference: Supervised Machine Learning for Detecting Fracture Hits

The primary objective of the study was development of a machine learning (ML)-based workflow for fracture hit (“frac hit”) detection and monitoring using shale oil-field data such as drilling surveys, production history (oil and produced water), pressure, and fracking start time and duration records. The ML method takes advantage of long short-term memory (LSTM) and multilayer perceptron (MLP) neural networks to identify the frac hits due to hydraulic communication between the fracking child well(s) and the producing parent well(s) within the same pad (intra-pad interaction) and/or on different pads (inter-pad interaction). It utilizes time series of pressure and production data from within a pad and from adjacent pads. The workflow can capture time variable features of frac hits when the model architecture is deep and wide enough, with enough trainable parameters for deep learning and feature extraction, as demonstrated in this paper by using training and testing subsets of the field data from selected neighboring pads with over a couple of hundred wells. The study was focused on frac-hit interaction among paired wells and demonstrated that the ML model, once trained, can predict the frac-hit probability.

58 GEOSCIENCES↗
DOE OSTI2024

Modeling Competing Line-broadening Mechanisms in Neutron Star Atmospheres: Interference between Motional Stark and Ion Broadening

Neutron star surfaces have extremely high magnetic fields. In the atmosphere, the broadening of spectral lines will be substantial from the dense plasma as well as from the magnetic field. One broadening mechanism of note is due to the motional Stark effect (MSE)—an additional electric field that arises from the motion of the atom in the magnetic field. However, approximate formulae are often used to construct atmosphere models, and the MSE is assumed to be the dominant line-broadening mechanism even in ions. Detailed pressure-broadening models in these extreme magnetic fields are now currently being developed. In these more detailed models, it was suggested that the MSE may not be as large as previously predicted. If correct, this hypothesis implies that neutron star line widths might be dominated by pressure broadening rather than by motional Stark broadening. We find that, in the absence of plasma perturbations, for typical magnetic fields (B = 10 12 G), mid-Z elements, such as oxygen, have motional Stark widths of order 1 eV for transitions between dipole-allowed transitions from the ground state, though higher temperatures and transitions to higher-energy states are expected to have more broadening. The MSE also breaks down selection rules, giving rise to forbidden transitions, which have much larger widths. When plasma perturbations are included, we find that the plasma perturbation and motional Stark processes are not independent and, as a result, the spectral lines become narrow in a nontrivial way and display harmonics of the ion cyclotron frequency.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2012

Design of a New Collimation System to Prevent Interference between X-ray Machines and Radiation Portal Monitors

Researchers at Oak Ridge National Laboratory (ORNL) developed a new collimation system that allows radiation portal monitors (RPMs) installed near x-ray machines to operate with a negligible false-positive alarm rate. RPMs are usually installed as far as possible from x-ray machines because false alarms are triggered by escaping x-rays; however, constraints at the installation site sometimes make it necessary that RPMs be installed near x-ray machines. Such RPMs are often plagued by high alarm rates resulting from the simultaneous operation of the RPMs and x-ray machines. Limitations on pedestrian flow, x-ray machine orientation, and RPM location often preclude a simple solution for lowering the alarm rate. Adding additional collimation to the x-ray machines to stop the x-rays at the source can reduce the alarm rate without interfering with site operations or adversely affecting the minimum detectable quantity of material (MDQ). A collimation design has been verified by measurements conducted at a RPM installation site and is applicable to all new and existing RPM installations near x-ray machines.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Electromagnetic interference filter for automotive electrical systems

A filter for an automotive electrical system includes a substrate having first and second conductive members. First and second input terminals are mounted to the substrate. The first input terminal is electrically connected to the first conductive member, and the second input terminal is electrically connected to the second conductive member. A plurality of capacitors are mounted to the substrate. Each of the capacitors is electrically connected to at least one of the first and second conductive members. First and second power connectors are mounted to the substrate. The first power connector is electrically connected to the first conductive member, and the second power connector is electrically connected to the second conductive member. A common mode choke is coupled to the substrate and arranged such that the common mode choke extends around at least a portion of the substrate and the first and second conductive members.

24 POWER TRANSMISSION AND DISTRIBUTION↗