Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Electrical signals”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Methods and devices for non-invasive root phenotyping

The present disclosure provides for an electronic sensor for detecting a root of a plant in soil, the electronic sensor that includes a first conductor plate configured to be disposed in soil, a switch, a power supply, and signal extractor. The switch is electrically coupled to the first conductor plate and is configured to switch between a first mode and a second mode. The power supply is electrically coupled to the switch and is configured to provide an electrical charge to the first conductor plate in the first mode of the switch. The signal extractor is electrically coupled to the switch and is configured to extract a signal response at the first conductor plate in the second mode of the switch. The present disclosure further provides a second conductor plate configured to be disposed in soil adjacent to and substantially parallel to the first conductor plate. The second conductor plate is electrically coupled to ground.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Methods and devices for non-invasive root phenotyping

The present disclosure provides for an electronic sensor for detecting a root of a plant in soil, the electronic sensor that includes a first conductor plate configured to be disposed in soil, a switch, a power supply, and signal extractor. The switch is electrically coupled to the first conductor plate and is configured to switch between a first mode and a second mode. The power supply is electrically coupled to the switch and is configured to provide an electrical charge to the first conductor plate in the first mode of the switch. The signal extractor is electrically coupled to the switch and is configured to extract a signal response at the first conductor plate in the second mode of the switch. The present disclosure further provides a second conductor plate configured to be disposed in soil adjacent to and substantially parallel to the first conductor plate. The second conductor plate is electrically coupled to ground.

Benfey, Philip N.↗
DOE OSTI2023

Methods and devices for non-invasive root phenotyping

The present disclosure provides for an electronic sensor for detecting a root of a plant in soil, the electronic sensor that includes a first conductor plate configured to be disposed in soil, a switch, a power supply, and a signal extractor. The switch is electrically coupled to the first conductor plate and is configured to switch between a first mode and a second mode. The power supply is electrically coupled to the switch and is configured to provide an electrical charge to the first conductor plate in the first mode of the switch. The signal extractor is electrically coupled to the switch and is configured to extract a signal response at the first conductor plate in the second mode of the switch. The present disclosure further provides a second conductor plate configured to be disposed in soil adjacent to and substantially parallel to the first conductor plate. The second conductor plate is electrically coupled to ground.

Benfey, Philip↗
NASA NTRS1974

Self-protecting solid state isolated switch

Solid state switch has following capabilities: (1) Hybrid or IC from compatible with direct mounting on solar array substrate; (2) Continuous signal is not required to hold it in either on or off state; (3) Separate signal lines for on and off control; (4) Electrically isolated from input signals; and (5) Current surges will not cause switch failure.

Hoffman, A. C.↗
NASA NTRS1982

Lightning detection and ranging

A lightning detector and ranging (LDAR) system developed at the Kennedy Space Center and recently transferred to Wallops Island is described. The system detects pulsed VHF signals due to electrical discharges occurring in a thunderstorm by means of 56-75 MHz receivers located at the hub and at the tips of 8 km radial lines. Incoming signals are transmitted by wideband links to a central computing facility which processes the times of arrival, using two independent calculations to determine position in order to guard against false data. The results are plotted on a CRT display, and an example of a thunderstorm lightning strike detection near Kennedy Space Center is outlined. The LDAR correctly identified potential ground strike zones and additionally provided a high correlation between updrafts and ground strikes.

Lennon, C. L.↗
DOE OSTI2025

Occupant-Centric Demand Response for Thermostatically-Controlled Home Loads

Efficiently managing energy usage to balance supply and demand on the electric grid is crucial, especially with the widespread deployment of distributed variable renewable electricity generation. This paper introduces two duty-cycle control methods for heating systems, adjusting thermostat setpoints to limit and shift electricity demand. The control approaches employ innovative techniques, such as adaptive duty cycling, to prioritize household thermal comfort while reducing peak demand. These control methods can respond to signals from the electric grid, including demand targets and time-of-use tariffs, and were tested physically on an electric furnace and heat pump in a test home during winter conditions in 2021 and 2022. The results are given as average demand reductions and energy use impacts with respect to the average indoor-outdoor temperature difference during the control period. For heat pumps, demand limiting control reduced power by 18.5% and 23.3% for indoor-outdoor temperature differences of 30°F and 40°F. Preheating-based demand shifting achieved reductions of 34.8% and 33.2% for the same temperature differences. Electric furnace tests showed demand reductions of 33.8% and 25.3% for demand limiting, and 56.1% and 45.7% for preheating-based demand shifting. These findings highlight the potential for innovative control methods to enhance grid efficiency and reduce energy consumption.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

System and method to characterize and identify operating modes of electric loads

A system characterizes and identifies one of a plurality of different operating modes of a number of electric loads. The system includes a processor; a voltage sensor providing a voltage signal for one of the electric loads to the processor; a current sensor providing a current signal for the one electric load to the processor; and a routine executed by the processor and structured to characterize the different operating modes using steady state and voltage-current trajectory features determined from the voltage and current signals, and to identify a particular one of the different operating modes based on a plurality of operating mode membership functions of the steady state and voltage-current trajectory features.

Yang, Yi↗
NASA NTRS1997

Rapid systemic up-regulation of genes after heat-wounding and electrical stimulation

When one leaf of a tomato plant is electrically-stimulated or heat-wounded, proteinase inhibitor genes are rapidly up-regulated in distant leaves. The identity of the systemic wound signal(s) is not yet known, but major candidates include hormones transmitted via the phloem or the xylem, the electrically-stimulated self-propagating electrical signal in the phloem (the action potential, AP), or the heat-wound-induced surge in hydraulic pressure in the xylem evoking a local change in membrane potential in adjacent living cells (the variation potential, VP). In order to discriminate between these signals we have adopted two approaches. The first approach involves applying stimuli that evoke known signals and determining whether these signals have similar effects on the "model" transcripts for proteinase inhibitors (pin) and calmodulin (cal). Here we show that a heat wound almost invariably evokes a VP, while an electrical stimulation occasionally evokes an AP, and both of these signals induce accumulation of transcripts encoding proteinase inhibitors. The second approach involves identifying the array of genes turned on by heat-wounding. To this end, we have constructed a subtractive library for heat-wounded tissue, isolated over 800 putatively up-regulated clones, and shown that all but two of the fifty that we have analyzed by Northern hybridization are, indeed, up-regulated. Here we show the early kinetics of up-regulation of three of these transcripts in the terminal (4th) leaf in response to heat-wounding the 3rd leaf, about 5 cm away. Even though these transcripts show somewhat different time courses of induction, with one peaking at 30 min, another at 15 min, and another at 5 min after flaming of a distant leaf, they all exhibit a similar pattern, i.e., a transient period of transcript accumulation preceding a period of transcript decrease, followed by a second period of transcript accumulation.

NASA Discipline Plant Biology↗
DOE OSTI2022

Extremum-Seeking-Based Ultra-local Model Predictive Control and Its Application to Electric Motor Speed Regulation

Electric vehicle (EV) market is rapidly expanding. As a critical component of EV, an electric motor needs to accurately follow a reference speed signal while respecting the electrical current constraint for safety. Those requirements are usually formulated as a model predictive control (MPC) problem. However, the performance of traditional model-based MPC depends on the accuracy of the system model, which may not always be guaranteed in reality. Therefore, we utilize a data-driven, model-free predictive control strategy, called ultra-local MPC (ULMPC), to control the speed of an electric motor. To further enhance the control performance of ULMPC, we employ the extremum-seeking control (ESC) to tune the control gain of the ULMPC online. Simulation and hardware experiments demonstrate the enhancement of the extremum-seeking-based ULMPC over a constant-gain ULMPC.

Zhou, Yujing↗
NASA NTRS1991

Airborne observations of electric fields around growing and decaying cumulus clouds

Airborne electric field data were gathered in an atmospheric electrification study near Cape Canaveral, FL. A Learjet 36A was instrumented with eight electric field meters (mills) and five different particle probes. The local electric field enhancements at each field mill site were determined under lab conditions and verified using in-flight data. The overdetermined system of eight equations (one for each field mill) was solved using a weighted least squares algorithm to compute the magnitude and direction of the ambient electric field. The signal processing system allowed the measured data to be expressed in terms of earth coordinates, regardless of the attitude of the aircraft. Thus, it was possible to take maximum advantage of the Learjet's speed and maneuverability in studying the electric field structure in the vicinity of the clouds. Data gathered while circling just outside the boundary of a growing cumulus cloud show a nonsymmetric pattern of electric field strength. Field intensity grew rapidly over a period of less than 10 minutes. The observed direction of the ambient electric field vector can be explained by an ascending motion of the charge centers of a classic tripole model of a thunderstorm.

Giori, K. L.↗
DOE OSTI2024

Fault-tolerant grid frequency measurement algorithm during transients

A system determines the frequency of grid signals corresponding to an electrical grid in real time. The system includes a transient detector that monitors a grid signal from a voltage meter or a current meter connected to the electrical grid. The system produces, in real time and at a sampling rate, a deviation signal indicative of a periodicity of the monitored grid signal. The system determines, over one or more cycles of the monitored grid signal, a measurement signal corresponding to the deviation signal. The system determines a frequency signal that corresponds a frequency estimation of the monitored signal by applying a frequency estimation when values of the measurement signal are less than a deviation threshold and maintaining the frequency signal at a constant value when values of the measured signal equal or exceeds the deviation threshold.

Zhan, Lingwei↗
NASA NTRS1990

Observation of an antenna-plasma instability

This paper investigates the conditions leading to, and the causes of, the phenomenon observed during a rocket flight (to 585-km altitude) of an occasionally occurring narrow-band signal on an electric antenna whose frequency was found to vary as the rocket turned. The amplitude also varied by a factor larger than can be explained by variable coupling to the plasma; maximum oscillation amplitude occurred when the antenna was aligned with the earth's magnetic field. A tentative explanation of this phenomenon is given, suggesting that the signals on the antenna were caused by an interacton of the flowing plasma with sheath waves around the antenna.

Kellogg, P. J.↗
NASA NTRS1977

Electric prototype power processor for a 30cm ion thruster

An electrical prototype power processor unit was designed, fabricated and tested with a 30 cm mercury ion engine for primary space propulsion. The power processor unit used the thyristor series resonant inverter as the basic power stage for the high power beam and discharge supplies. A transistorized series resonant inverter processed the remaining power for the low power outputs. The power processor included a digital interface unit to process all input commands and internal telemetry signals so that electric propulsion systems could be operated with a central computer system. The electrical prototype unit included design improvement in the power components such as thyristors, transistors, filters and resonant capacitors, and power transformers and inductors in order to reduce component weight, to minimize losses, and to control the component temperature rise. A design analysis for the electrical prototype is also presented on the component weight, losses, part count and reliability estimate. The electrical prototype was tested in a thermal vacuum environment. Integration tests were performed with a 30 cm ion engine and demonstrated operational compatibility. Electromagnetic interference data was also recorded on the design to provide information for spacecraft integration.

Biess, J. J.↗
NASA NTRS1994

Electrical characterization of a Space Station Freedom alpha utility transfer assembly

Electrical power, command signals and data are transferred across the Space Station Freedom solar alpha rotary joint by roll rings, which are incorporated within the Utility Transfer Assembly (UTA) designed and manufactured by Honeywell Space Systems Operations. A developmental Model of the UTA was tested at the NASA Lewis Research Center using the Power Management and Distribution DC test bed. The objectives of these tests were to obtain data for calibrating system models and to support final design of qualification and flight units. This testing marked the first time the UTA was operated at high power levels and exposed to electrical conditions similar to that which it will encounter on the actual Space Station. Satisfactory UTA system performance was demonstrated within the scope of this testing.

Yenni, Edward J.↗
DOE OSTI2022

Dual-Color Optical Recording of Bioelectric Potentials by Polymer Electrochromism

Optical recording based on voltage-sensitive fluorescent reporters allows for spatial flexibility of measuring from desired cells, but photobleaching and phototoxicity of the fluorescent labels often limit their sensitivity and recording duration. Voltage-dependent optical absorption, rather than fluorescence, of electrochromic materials, would overcome these limitations to achieve long-term optical recording of bioelectrical signals. Electrochromic materials such as PEDOT:PSS possess the property that an applied voltage can either increase or decrease the light absorption depending on the wavelength. In this work, we harness this anticorrelated light absorption at two different wavelengths to significantly improve the signal detection. With dual-color detection, electrical activity from cells produces signals of opposite polarity, while artifacts, mechanical motions, and technical noises are uncorrelated or positively correlated. Using this technique, we are able to optically record cardiac action potentials with a high signal-to-noise ratio, 10 kHz sampling rate, >15 min recording duration, and no time-dependent degradation of the signal. Furthermore, we can reliably perform multiple recording sessions from the same culture for over 25 days.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2018

RFID-Enabled Angular Position Sensing System

An angular position sensing system includes a first support with ring-shaped elements disposed thereon and spaced apart from one another in a curvilinear arrangement. Each ring-shaped element includes an electrically-conductive ring and an RFID integrated circuit electrically coupled to its electrically-conductive ring. A second support has an antenna coupled thereto that defines an electrically-conductive path commensurate in size and shape to at least a portion of the electrically-conductive ring. An interrogator transmits a signal to the antenna wherein electric current is generated along the antenna's electrically-conductive path and electromagnetic energy emanates from the antenna. Any ring-shaped element and its RFID integrated circuit energized by the electromagnetic energy generates in response a data transmission for receipt by the interrogator. A processor coupled to the interrogator derives information related to an angular position of one of the first support and second support using the data transmission.

Fink, Patrick W.↗
DOE OSTI2025

Electrical Detection of Spin-Hall-Induced Auto-oscillations in Lithium Aluminate Ferrite Thin Films

Ferrimagnetic insulators with ultralow damping are of great interest for their potential applications in energy-efficient computing devices. Here, we report the direct electrical detection of magnetic auto-oscillations in unpatterned ultralow damping ferrimagnetic insulator epitaxial Li 0.5 Al 0.5 Fe 2 O 4 thin films, driven by a current in a proximal Pt nanowire. Auto-oscillations occur for only one current polarity, consistent with the spin-Hall effect inducing the oscillation state. Micromagnetic modeling shows good agreement with the experimental frequency and field dispersions, showing only one dominant oscillation mode, in contrast to the multiple modes typically observed in transition-metal nanowire-type spin-Hall nanooscillators. This study illustrates a new material system for neuromorphic computing and magnonics, a simple material platform with the direct-current generation of high-frequency (~10 GHz) signals and their electrical detection.

36 MATERIALS SCIENCE↗