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Results for “State Estimation”

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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Multi-state residential transaction estimates of solar photovoltaic system premiums

We report that as of the second quarter of 2016 more than 1.1 million solar photovoltaic (PV) homes exist in the US. Capturing the value these PV systems add to home sales is therefore important. Our study enhances the PV-home-valuation literature by analyzing 22,822 home sales, of which 3951 have PV, and which span eight states during 2002–2013. We also, for the first time, compare premiums with contributory value estimates derived from the present value of saved energy costs (income approach) and, separately, the replacement cost of systems at the time of sale (cost approach) to examine market signals. We find home buyers are consistently willing to pay PV home premiums across various states, housing and PV markets, and home types; average premiums equate to approximately $4/W or $15,000 for an average-sized 3.6-kW PV system. We find that a replacement cost net of state and federal incentives is a better proxy for premiums than gross installed costs, and that the income approach is a good signal if it accounts for tiered volumetric retail rates. Finally, other results include detailed premium analyses for PV home sub-populations.

14 SOLAR ENERGY↗
DOE OSTI2014

A Phenomenological Model of Bulk Force in a Li-Ion Battery Pack and Its Application to State of Charge Estimation

A phenomenological model of the bulk force exerted by a lithium ion cell during various charge, discharge, and temperature operating conditions is developed. The measured and modeled force resembles the carbon expansion behavior associated with the phase changes during intercalation, as there are ranges of state of charge (SOC) with a gradual force increase and ranges of SOC with very small change in force. The model includes the influence of temperature on the observed force capturing the underlying thermal expansion phenomena. Moreover the model is capable of describing the changes in force during thermal transients, when internal battery heating due to high C-rates or rapid changes in the ambient temperature, which create a mismatch in the temperature of the cell and the holding fixture. It is finally shown that the bulk force model can be very useful for a more accurate and robust SOC estimation based on fusing information from voltage and force (or pressure) measurements. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email oa@electrochem.org. All rights reserved.

Mohan, S↗
NASA NTRSDate not supplied

Remote Guidance of a Mothership-Daughtership Formation for Asteroid Exploration

This work presents an application of Model Predictive Control to maintain long-term stability for a three-satellite formation around the asteroid Apophis via remote guidance. The mothership and two daughterships perform tomographic characterization with a bistatic radar. The mothership estimates the states of all three spacecraft and determines the necessary control to maintain the desired antipodal daughtership states. An Extended Kalman Filter estimates the mothership states. A Batch Least Squares algorithm estimates the daughtership states and performs maneuver reconstruction for the mothership-administered thrust commands under thruster and gravitational uncertainty. The formulation maintains the antipodal angle with growing instability amidst these uncertainties.

Guidance↗
DOE OSTI2019

Bond Wire Damage Detection and State of Health Estimation of a 1200V, 900A Dual Pack IGBT Power Module using the RL-Equivalent Circuit

Electrical and environmental stresses are the two dominant contributors in aging and failure of power semiconductor devices. Insulated gate bipolar junction transistors (IGBTs) and metal-oxide semiconductor field effect transistors (MOSFETs) are two most commonly used switching devices in power converter circuits. A significant portion of research effort is given in inventing innovative methods to estimate the degradation and fatigue in these devices. Until today, no other existing techniques can determine the number of lifted bond wires and their locations in a live IGBT module, although this information is extremely helpful to understand the overall state of health of an IGBT power module. In this paper, we have proposed a reflectometry-based technique to overcome this hurdle. The RL-equivalent circuit to represent a bond wire has been developed for the device under test and simulated in CST Studio Suite to measure the reflection amplitudes. Experimental results were obtained using a prototype reflectometry hardware, and both the simulation and experimental results have been compared. These results prove that with these two sets of measurements, it is possible to locate the aged device inside a module and detect the number of bond wire lift-offs associated to that device.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2018

Bulk force in a battery pack and its application to state of charge estimation

There is disclosed an electrical device including a battery pack, a pressure sensor for measuring a volume change of the battery pack, a voltage sensor in electrical communication with a positive terminal and a negative terminal of the battery pack, a temperature sensor positioned in a cell of the battery pack, and a battery management system. The battery management system includes a controller in electrical communication with the pressure sensor, the voltage sensor, and the temperature sensor, the controller being configured to execute a program stored in the controller to determine a state of charge percentage of the battery pack based on a pressure reading from the pressure sensor, a terminal voltage reading from the voltage sensor, and a temperature reading from the temperature sensor.

Stefanopoulou, Anna G.↗
DOE OSTI2014

Evaluating the Accuracy and Precision of Multiple Abundance Estimators Using State-Space Models: A Case Study for a Threatened Population of Chinook Salmon in Johnson Creek, Idaho

Abstract Over the last century, Chinook Salmon Oncorhynchus tshawytscha populations in the Pacific Northwest have experienced dramatic declines, leading to many of them being listed as threatened under the Endangered Species Act. The abundance of these threatened populations relative to the thresholds for delisting remains the primary metric for assessing recovery, yet determining the true population abundances from multiple survey types with unknown levels of accuracy and precision remains difficult. The abundance of the spring–summer Chinook Salmon population in Johnson Creek, Idaho, has been measured using a mark–recapture survey and three different redd count surveys (RCSs) that vary temporally and spatially. Using a state-space model, we determined the accuracy and precision of each survey type by decoupling the observation error of the survey from the process error describing the annual variability in the true population abundance. We then extended the results of the model to determine the risk of managers’ incorrectly delisting the population (a type I error) or incorrectly keeping it listed (a type II error). Finally, we show that salmon managers with data-limited populations (primarily those with only single-pass index RCSs) might use the results of our risk analysis to determine whether expanding survey efforts to minimize management risks is appropriate when they are confronted with dwindling financial resources. For example, we determined that although both the multiple-pass extended RCS (CV = 0.06) and mark–recapture surveys (CV = 0.14) provide unbiased estimates of salmon abundance in Johnson Creek, the mark–recapture study can have annual costs that are 30–100 times greater. Managers may determine that directing research funds toward acquiring information unique to weir-based mark–recapture surveys (i.e., migration timing, good genetics samples, etc.) may not be justified for all populations. Received October 7, 2013; accepted March 5, 2014

Chasco, Brandon E.↗
NASA NTRS1994

Deformation across the western United States: A local estimate of Pacific-North America transform deformation

We obtain a locally based estimate of Pacific-North America relative motion and an uncertainly in this estimate by integrating deformation rate along three different paths leading west across southwestern North America from east of the Rio Grande Rift to near the continental escarpment. Data are primarily Quatenary geologic slip rates estimates, and resulting deformation determinations therefore are 'instantaneous' in a geologic sense but 'long term' with respect to earthquake cycles. We deduce a rate of motion of the Pacific plane relative to North America that is 48 +/- 2 mm/yr, a rate indistinguishable from that predicted by the global kinematics models RM2 and NUVEL-1; however, we obtain an orientation that is 5-9 deg counterclockwise of these models. A more westerly motion of the Pacific plate, with respect to North America, is calculated from all three paths. The relatively westerly motion of the Pacific plate is accomodated by deformation in the North American continent that includes slip on relatively counterclockwise-oriented strike-slip faults (including the San Andreas fault), whic is especially relevant in and south of the Transverse Ranges, and a margin-normal component of net extension across the continent, which is especially relevant north of the Transverse Ranges. Deformation of the SW United States occurs in regionally coherent domains within the style of deformation is approximately uniform.

Humphreys, Eugene D.↗
DOE OSTI2018

Combined Mini-Cylex & Disk Acceleration Tests in Type K Copper

In this work, we combined the miniature cylinder expansion test (Mini-Cylex), with the Disk Acceleration Test (DAX) using Type K copper, Picatinny Liquid Explosive, and photonic Doppler velocimetry. We estimated the CJ state using plate reverberation methods at the test cap. We extracted velocities at 2, 7, and 10 volume expansions to fit Jones-Wilkins-Lee Equation of State and estimated Gurney velocity at the tube wall. The test also provides an additional method to estimate reaction products Hugoniot through knowledge of the copper test cap. Our experiments and simulations are within expected uncertainty. Lastly, the test and the analysis effectively reduce costs while keeping or increasing fidelity.

42 ENGINEERING↗