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DOE OSTI2024

Identifying Meteorological Drivers for Errors in Modeled Winds along the Northern California Coast

Abstract An accurate wind resource dataset is required for assessing the potential energy yield of floating offshore wind farms that are expected along the California outer continental shelf. The National Renewable Energy Laboratory has developed and disseminated an updated wind resource dataset offshore of California, using the Weather Research and Forecasting Model, referred to as the CA20 dataset. As compared to buoy lidar measurements that have become available recently, the CA20 dataset showed significant positive biases for 100-m wind speeds along Northern California wind energy lease areas. To investigate the meteorological drivers for the model errors, we first consider two 1-yr simulations run with two different planetary boundary layer (PBL) parameterizations: the Mellor–Yamada–Nakanishi–Niino (MYNN) PBL scheme (the chosen configuration in the CA20 dataset) and the Yonsei University PBL scheme (which significantly reduces the bias in modeled winds). By comparing the 1-yr simulations to the concurrent lidar buoy observations, we find that errors are larger with the MYNN PBL scheme in warm seasons. We then dive deeper into the analysis by running simulations for short-term (3-day) case studies to evaluate the sensitivity of initial/boundary condition forcings on model results. By analyzing the short-term simulations, we find that during synoptic-scale northerly flows driven by the North Pacific high and inland thermal low, a coastal warm bias in the MYNN simulation is mainly responsible for the modeled wind speed bias by altering the boundary layer thermodynamics. The results of our analysis will help guide the creation of an updated version of the CA20 dataset.

17 WIND ENERGY↗

DOE OSTI2023

Evaluating the Interplay between Trajectory Segmentation and Mode Inference Error

Travel behavior changes are essential to transportation decarbonization. Travel diaries, consisting of sequences of trips between places, are typically used to instrument human travel behavior. However, these diaries are only as accurate as the underlying methods used to construct them. Travel diary algorithms have been a popular research topic since the advent of Global Positioning System tracking surveys. These algorithms have typically been validated using prompted recall of presegmented trips, thus disregarding the continuity of mode inference. Phone operating systems have adopted battery-conserving techniques, but the resulting data collection errors have not been studied extensively. We introduce a framework to evaluate the accuracy of trip length computations and mode inference by analyzing continuous mode-segmented trajectories for groups of trips. We then use the framework to identify the input data quality and the impact of postprocessing. Our primary inputs to this evaluation are MobilityNet, a public dataset containing information from three artificial timelines covering 15 different travel modes, and sample open-source travel diary creation algorithms from the OpenPATH project. Our framework concretely shows that the variance of the distance error drops from (0.217, 0.0848) to (o.011, 0.0407) (Android, iOS) after postprocessing. Similarly, the weighted F-scores for mode inference increase from (0.25, 0.29) to (0.60, 0.74) (iOS, Android) between random forest and geographic information system-based models. We hope that this standardized method will be adapted to evaluate other, potentially proprietary, travel diary algorithms. Finally, the results can be used to understand and improve the state of the art in the travel diary creation field.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2017

Simplified model of pinhole imaging for quantifying systematic errors in image shape

In this paper, we examine systematic errors in x-ray imaging by pinhole optics for quantifying uncertainties in the measurement of convergence and asymmetry in inertial confinement fusion implosions. We present a quantitative model for the total resolution of a pinhole optic with an imaging detector that more effectively describes the effect of diffraction than models that treat geometry and diffraction as independent. This model can be used to predict loss of shape detail due to imaging across the transition from geometric to diffractive optics. We find that fractional error in observable shapes is proportional to the total resolution element we present and inversely proportional to the length scale of the asymmetry being observed. Finally, we have experimentally validated our results by imaging a single object with differently sized pinholes and with different magnifications.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2019

Two-color pyrometry system to eliminate optical errors for spatially resolved measurements in flames

Two color (2C) pyrometry has long been used to measure flame temperature and soot concentration from radiative emission in flames. While 2C pyrometry is not an absolute measurement in non-axisymmetric flames (such as diesel spray combustion) it is a desirable diagnostic for semi-quantitative or qualitative measurements since it requires minimal optical access and can utilize high-speed imaging to attain exceptional temporal and spatial resolution. In this work, an improved optical configuration of 2C pyrometry is presented that 1) eliminates optical errors inherent in other designs, and 2) uses off-the-shelf optics and a single camera . In particular, this work analyzes the impact of parallax and path length differences on the 2C pyrometry measurement and exemplifies how the present design eliminates associated errors by design rather than in post-processing. Finally, the theoretical range of measurements were generated a priori and overlaid with experimental data to illustrate the dynamic range over which 2C pyrometry can determine the soot concentration and temperature in theory and in practice.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Towards a study protocol: A data-driven workflow to identify error sources in direct ink write mechatronics

Abstract Using Direct Ink Write (DIW) technology in a rapid and large-scale production requires reliable quality control for printed parts. Data streams generated during printing, such as print mechatronics, are massive and diverse which impedes extracting insights. In our study protocol approach, we developed a data-driven workflow to understand the behavior of sensor-measured X- and Y- axes positional errors with process parameters, such as print velocity and velocity control. We uncovered patterns showing that instantaneous changes in the velocity, when the build platform accelerates and decelerates, largely influence the positional errors, especially in the X- axis due to the hardware architecture. Since DIW systems share similar mechatronic inputs and outputs, our study protocol approach is broadly applicable and scalable across multiple systems. Graphical abstract

36 MATERIALS SCIENCE↗

DOE OSTI2017

Identifying and Correcting Timing Errors at Seismic Stations in and around Iran

A fundamental component of seismic research is the use of phase arrival times, which are central to event location, Earth model development, and phase identification, as well as derived products. Hence, the accuracy of arrival times is crucial. However, errors in the timing of seismic waveforms and the arrival times based on them may go unidentified by the end user, particularly when seismic data are shared between different organizations. Here, we present a method used to analyze travel-time residuals for stations in and around Iran to identify time periods that are likely to contain station timing problems. For the 14 stations with the strongest evidence of timing errors lasting one month or longer, timing corrections are proposed to address the problematic time periods. Finally, two additional stations are identified with incorrect locations in the International Registry of Seismograph Stations, and one is found to have erroneously reported arrival times in 2011.

58 GEOSCIENCES↗

DOE OSTI2023

Status of Error Correction Studies in Support of FFA@CEBAF

In pursuit of higher energy at the Continuous Electron Beam Accelerator Facility (CEBAF), the FFA@CEBAF energy upgrade study is considering the implementation of a novel technology to recirculate electron beam through the accelerating gradient of the machine more times. The technology in question is Fixed-Field Alternating-gradient (FFA) bending accelerator arcs: these arcs may replace the present highest energy electromagnetic (EM) arcs, and due to a much wider energy acceptance allow several more passes. The survey and beam error tolerance of the FFA arcs need to be well understood prior to commissioning, in addition to the limits of planned correction magnets and diagnostics. This work explores the current state of error tolerance and correction studies in FFA arcs at CEBAF.

Benesch, J.↗

DOE OSTI2024

FFA@CEBAF beam transport error and tolerance simulation studies

The Continuous Electron Beam Accelerator Facility (CEBAF) is a 12 GeV recirculating electron accelerator at the Thomas Jefferson National Accelerator Facility (JLAB). Major upgrades to the accelerator are being investigated which include a new 650 MeV injection beamline and state-of-the-art fixed-field alternating (FFA) gradient recirculation arcs. The upgrade will extend the energy of the electron beam to over 20 GeV. In this paper, we provide an error and tolerance simulation study of the amended beam optics transport of the existing accelerator tuned for 22 GeV operation. The study is conducted with the particle tracking codes elegant and Bmad in two parts. In the first part, we treat each section of the accelerator (electromagnetic arcs and linacs) modularly with ideal conditions at the beginning. The second part is a pseudo start-to-end (S2E) simulation with accumulated errors propagating from one beamline to the next.

Accelerator Physics↗

DOE OSTI2024

Error-correcting codes for fermionic quantum simulation

Utilizing the framework of \mathbb{Z}_2 ℤ 2 lattice gauge theories in the context of Pauli stabilizer codes, we present methodologies for simulating fermions via qubit systems on a two-dimensional square lattice. We investigate the symplectic automorphisms of the Pauli module over the Laurent polynomial ring. This enables us to systematically increase the code distances of stabilizer codes while fixing the rate between encoded logical fermions and physical qubits. We identify a family of stabilizer codes suitable for fermion simulation, achieving code distances of d=2,3,4,5,6,7, allowing correction of any \lfloor \frac{d-1}{2} \rfloor ⌊ d − 1 2 ⌋ -qubit error. In contrast to the traditional code concatenation approach, our method can increase the code distances without decreasing the (fermionic) code rate. In particular, we explicitly show all stabilizers and logical operators for codes with code distances of d=3,4,5. We provide syndromes for all Pauli errors and invent a syndrome-matching algorithm to compute code distances numerically.

Physics↗

DOE OSTI2013

Precomparator and postcomparator errors in monopulse.

Monopulse radar is a well-established technique for extracting accurate target location information in the presence of target scintillation. It relies on the comparison of at least two patterns being received simultaneously by the antenna. These two patterns are designed to differ in the direction in which we wish to obtain the target angle information. The two patterns are compared to each other through a standard method, typically by forming the ratio of the difference of the patterns to the sum of the patterns. The key to accurate angle information using monopulse is that the mapping function from the target angle to this ratio is well-behaved and well-known. Errors in the amplitude and phase of the signals prior and subsequent to the comparison operation affect the mapping function. The purpose of this report is to provide some intuition into these error effects upon the mapping function.

Bickel, Douglas Lloyd↗

DOE OSTI2015

Detecting Soft Errors in Stencil based Computations

Given the growing emphasis on system resilience, it is important to develop software-level error detectors that help trap hardware-level faults with reasonable accuracy while minimizing false alarms as well as the performance overhead introduced. We present a technique that approaches this idea by taking stencil computations as our target, and synthesizing detectors based on machine learning. In particular, we employ linear regression to generate computationally inexpensive models which form the basis for error detection. Our technique has been incorporated into a new open-source library called SORREL. In addition to reporting encouraging experimental results, we demonstrate techniques that help reduce the size of training data. We also discuss the efficacy of various detectors synthesized, as well as our future plans.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2017

Error Analysis of CM Data Products Sources of Uncertainty

This goal of this project is to address the current inability to assess the overall error and uncertainty of data products developed and distributed by DOE’s Consequence Management (CM) Program. This is a widely recognized shortfall, the resolution of which would provide a great deal of value and defensibility to the analysis results, data products, and the decision making process that follows this work. A global approach to this problem is necessary because multiple sources of error and uncertainty contribute to the ultimate production of CM data products. Therefore, this project will require collaboration with subject matter experts across a wide range of FRMAC skill sets in order to quantify the types of uncertainty that each area of the CM process might contain and to understand how variations in these uncertainty sources contribute to the aggregated uncertainty present in CM data products. The ultimate goal of this project is to quantify the confidence level of CM products to ensure that appropriate public and worker protections decisions are supported by defensible analysis.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2018

The Alignment Error Estimates of Magnet and Girder

The alignment tolerances from physics group are set as ± 30 micron (±1σ) for magnets in common girders and ± 100 micron (±1σ) for girders when they are positioned in tunnel. Though, physics group don’t want any components be misaligned out of that boundary. This article will present all the possible error sources and give an overall error estimate of those two key processes. The measures that ensure no components fall out of the boundary will be illustrated as well.

42 ENGINEERING↗

DOE OSTI2014

Addressing Model Form Error for Time-Dependent Conservation Equations

Model form error of the type considered here is error due to an approximate or incorrect representation of physics by a computational model. Typical approaches to adjust a model based on observed differences between experiment and prediction are to calibrate the model parameters utilizing the observed discrepancies and to develop parameterized additive corrections to the model output. These approaches are generally not suitable if significant physics is missing from the model and the desired quantities of interest for an application are different than those used for calibration. The approach developed here is to build a corrected surrogate solver through a multi- step process: 1) Sampled simulation results are used to develop a surrogate computational solver that maintains the overall conservative principles of the unmodified governing equations, 2) the surrogate solver is applied to candidate linear and non-linear corrector terms to develop corrections that are consistent with the original conservative principles, 3) constant multipliers on the these terms are calibrated using the experimental observations, and 4) the resulting surrogate solver is used to predict application response for the quantity of interest. This approach and several other calibration-based approaches were applied to an example problem based on the diffusive Burgers' equation. While all the approaches provided some model correction when the measure/calibration quantity was the same as that for an application, only the present approach was able to adequately correct the CompSim results when the prediction quantity was different from the calibration quantity.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2013

The alignment error estimates of magnet and girder

36 MATERIALS SCIENCE↗

DOE OSTI2019

Beam Dynamics Study of PIP-II Superconducting Linac in the Presece of Misalignment Errors

The Proton Improvement Plan (PIP)-II is a proposed high intensity proton facility being developed at the Fermilab. The PIP-II is primarily based on construction of a new superconducting radio frequency (SRF) linear accelerator (linac) that would deliver an average beam current of 2mA with output energy up to 800 MeV. The linac performance is mainly determined by beam sensitivity against various component errors. These errors trigger not only emittance dilution but also a beam loss in worst cases. This paper discusses effects of component misalignments on the beam and presents alignment budget for the PIP-II SRF linac.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

Error Study of FlecSim Using the Method of Manufactured Solutions [Slides]

Error was calculated using exact solution chosen with the method of manufactured solutions. Hydrodynamics match expected order of accuracy for spatial error within 1.5% for all variables tested. Radiation transport matches expected order of temporal accuracy within 0.5% for all variables tested.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

The Single Event Error (SEE) test and analysis of the CMS Endcap Timing Layer readout chip

The ETROC2, the first full size and full functionality prototype chip for the CMS Endcap Timing Layer readout, is strategically designed to meet the SEE immunity requirements of detector operation with the low power constraint. The triplicated periphery and pixel I2C configuration registers are designed with self-correction feature. The pixel readout control is centralized in the global readout and fully triplicated. The pixel readout is not triplicated, instead protected with power-efficient one-bit correction Hamming code. The TMR protection of the on-pixel threshold calibration can be turned off allowing the detection of the beam spot during the beam test by checking the bit-flips of the internal memory cells. In the initial proton beam test in January 2024, the chip readout process did not hang throughout the tests. The Hamming code correction strategy works because the error corrected TDC data were observed in the data frames. The error-injection simulation is performed to analy ze the small number of bit-flips in the configuration registers. We also performed SEE testing with a heavy ion beam in April and the data analysis is ongoing. The detailed design on the SEE immunity and the testing as well as simulation results will be presented, including follow-up SEE testing results in May and June 2024.

Gong, Datao↗