Scanning Position Research Articles

AI-assisted automated workflow for real-time x-ray ptychography data analysis via federated resources

We present an end-to-end automated workflow that uses large-scale remote compute resources and an embedded GPU platform at the edge to enable AI/ML-accelerated real-time analysis of data collected for x-ray ptychography. Ptychography is a lensless method that is being used to image samples through a simultaneous numerical inversion of a large number of diffraction patterns from adjacent overlapping scan positions. This acquisition method can enable nanoscale imaging with x-rays and electrons, but this often requires very large experimental datasets and commensurately high turnaround times, which can limit experimental capabilities such as real-time experimental steering and low-latency monitoring. In this work, we introduce a software system that can automate ptychography data analysis tasks. We accelerate the data analysis pipeline by using a modified version of PtychoNN -- an ML-based approach to solve phase retrieval problem that shows two orders of magnitude speedup compared to traditional iterative methods. Further, our system coordinates and overlaps different data analysis tasks to minimize synchronization overhead between different stages of the workflow. We evaluate our workflow system with real-world experimental workloads from the 26ID beamline at Advanced Photon Source and ThetaGPU cluster at Argonne Leadership Computing Resources.

A METHOD FOR DETECTION OF DOORS IN BUILDING INDOOR POINT CLOUD THROUGH MULTI-LAYER THRESHOLDING AND HISTOGRAM ANALYSIS

Abstract. Indoor navigation is a critical service providing safe paths for humans in an emergency. Since doors connect different parts of a building, door detection is essential in creating a navigation map and walkable spaces. Considering the Manhattan World Assumption (MWA), this paper proposes a method for detecting doors that connect two scanned rooms. In contrast with most existing approaches, the proposed method requires neither trajectory nor scanning position. This method consists of two main steps. At first, with the help of multi-layer thresholding, a raster will be created from the point cloud that its Digital Numbers (DNs) correspond to the ceiling elevation. Then, this raster's pixels will be segmented based on their DNs, and those segments whose elevations are local minimums are chosen as door candidates. The second step extracts the part of the point cloud corresponding to each door candidate and analyses its coordinates components' histograms to decide whether there is a door or not. The proposed scheme has been tested on two different datasets and could accurately detect 91% of the inner doors. Although this method is designed to detect inner doors, it also detected 65% of marginal doors.

Phase Object Reconstruction for 4D-STEM using Deep Learning

Abstract In this study, we explore the possibility to use deep learning for the reconstruction of phase images from 4D scanning transmission electron microscopy (4D-STEM) data. The process can be divided into two main steps. First, the complex electron wave function is recovered for a convergent beam electron diffraction pattern (CBED) using a convolutional neural network (CNN). Subsequently, a corresponding patch of the phase object is recovered using the phase object approximation. Repeating this for each scan position in a 4D-STEM dataset and combining the patches by complex summation yields the full-phase object. Each patch is recovered from a kernel of 3×3 adjacent CBEDs only, which eliminates common, large memory requirements and enables live processing during an experiment. The machine learning pipeline, data generation, and the reconstruction algorithm are presented. We demonstrate that the CNN can retrieve phase information beyond the aperture angle, enabling super-resolution imaging. The image contrast formation is evaluated showing a dependence on the thickness and atomic column type. Columns containing light and heavy elements can be imaged simultaneously and are distinguishable. The combination of super-resolution, good noise robustness, and intuitive image contrast characteristics makes the approach unique among live imaging methods in 4D-STEM.

Multiobjective Optimization-Based Terrestrial Laser Scanning Layout Planning for Landslide Monitoring

Terrestrial laser scanning (TLS) is an important means to monitor landslides, and the layout is the key to guarantee captured point clouds with a high quality and low cost. Nevertheless, TLS layout in landslide monitoring is currently determined by user’s subjective experience, and shows a poor performance in reliability and point accuracy. Therefore, we propose multi-objective optimization based TLS layout planning for landslide monitoring. Three-dimensional (3D) scanning simulation of candidate scan positions is first carried out. A multi-objective optimization problem (MOP) is then constructed according to requirements of landslide TLS monitoring in the coverage, cost, and point accuracy. Finally, the combination of an improved non-dominated sorting genetic algorithm Ⅱ (NSGA-II) and the Pareto-Edgeworth-Grierson (PEG) algorithm is introduced to solve the MOP and obtain the optimal layout. To test the proposed method, experiments were performed in two landslide sites in Wuhan, China. Results showed that the planned TLS layouts reached a trade-off among coverage, point accuracy, and the number of TLS scan positions. Comparison experiments based on simulation demonstrated that the constraints fused into NSGA-II dramatically improved the reliability of the planned TLS layout, and the proposed method improved the coverage and point accuracy by 11.62% and 1.52 times compared to the user’s experience. Real scanning demonstrated the proposed method improved the coverage by 10.48%, and reduced the deformation error by 0.78 mm~7.66 mm compared to the user’s experience. In summary, the proposed method is an efficient approach for TLS layout planning, which can improve the ability of landslide TLS monitoring.

Detection of subsurface defects in silicon carbide bulk materials with photothermal radiometry

<sec>With excellent physical, mechanical and processing properties, silicon carbide (SiC) has gradually become a preferred lightweight optical material for primary mirrors of large space optical systems. The subsurface defects generated during the preparation and processing procedures of SiC will affect the optical quality of the primary mirrors and the imaging performance of the corresponding optical systems employing the SiC primary mirror as well. In this work, photothermal radiation (PTR), a powerful nondestructive testing technique for detecting sub-surface defects of solid materials, is employed to characterize the subsurface defects of bulk SiC material for primary mirrors.</sec><sec>Theoretically, three-dimensional one-layer and three-layer PTR theoretical models are developed to describe the defect-free and defect regions of an SiC bulk material. By analyzing the frequency dependence of PTR phase of the SiC bulk material with different defect depths, an empirical formula for estimating the defect depth via a characteristic frequency (appearing at the minimum of the PTR phase-frequency curve) defined thermal diffusion length is proposed, and simulation results show reasonably good agreement between the estimated and simulated defect depths in a depth range of 0.05–0.50 mm. Experimentally, an SiC bulk sample with a subsurface defect region is tested by the PTR via position scanning and modulation frequency scanning to obtain the position and frequency dependent PTR amplitude and phase. From the spatial distributions of PTR amplitude and phase measured at different frequencies and the phase difference frequency curves of measurement positions in the defect region, the depth and shape of the defect region are estimated and found to be in good agreement with the actual shape of the defect region, which is destructively measured via a depth profiler. The experimental and calculated results demonstrate that the PTR is capable of detecting non-destructively the subsurface defects of SiC bulk material. In addition, for subsurface defects with relatively flat interface, the defect depth can be determined accurately by the developed empirical formula.</sec>

Scene point cloud understanding and reconstruction technologies in 3D space

Scene point cloud understanding and reconstruction technologies in 3D space

Terrestrial laser scanning for 3D mapping of an alpine ice cave.

Perennial ice deposits in caves are an underexplored component of the cryosphere preserving a largely untapped archive of long-term changes in landscape and climate whose existence is threatened by climate change. This study demonstrates how terrestrial laser scanning (TLS) can be used to fully and accurately (registration accuracy < 1 cm standard deviation of point differences) assess the geometry of an ice-bearing cave in the Eastern Alps (Tyrol, Austria). Three TLS campaigns and 255 scan positions were used to acquire point clouds with a high sampling density (2 cm average point spacing) in order to minimise shading effects and to assure a precise and highly resolved 3D documentation of the cave. A semi-automated registration and point cloud-processing approach adapted to the site-specific demands ensured a complete and error-minimised assessment of the cave's geometry serving as a solid basis for future quantifications of snow and ice content dynamics. Dominant cave surface structures were investigated by performing a multiscale principal component analysis (PCA) to identify a detailed and computationally efficient basis for future airflow modelling tasks.

Virtual-force-guided intraoperative ultrasound scanning with online lesion location prediction: A phantom study.

In ultrasound-guided minimally invasive surgery (MIS) of tumours, it is crucial to discover the optimal scanning plane (OSP) and organise the MIS scalpel work trajectory in this plane. The OSP can be altered and is challenging to track when the scalpel interacts with deformed tissues. Therefore, tracking the OSP becomes critical in MIS. In master-slave control, virtual force (VF) is used to assist the operator in completing the task. However, most literature assumes that the environment is sufficiently stable. No specific method focuses on tracking the OSP of the lesion within largely deformed tissues. This paper used the improved artificial potential field method to establish the VF that could guide the operator to track the OSP. When tissue deformation occurred, an artificial neural network (ANN) was used to predict the target position, guiding the operator to find the new OSP. An experimental robot platform was built to verify the proposed algorithm's effects. Experiments to track the OSP were performed on a phantom. The results showed that the presented method could reduce the trajectory redundancy of ultrasonic scanning, shorten the time of OSP discovery and tracking, and decrease the deviation between the ultrasonic scanning position and the OSP. This method has significance for the accurate localization and successful removal of tumours. Future work will focus on improving the adaptability of the proposed ANN prediction model in different phantoms.

Quantified Approach for Evaluation of Geometry Visibility of Optical-Based Process Monitoring System for Laser Powder Bed Fusion

The long-term sustainability of the Additive Manufacturing (AM) industry not only depends on the ability to produce parts with reproducible quality and properties to a large extent but also on the standardization of the production processes. In that regard, online process monitoring and detection of defective parts during production become inevitable. Optical-based process monitoring techniques are popular; however, most work has been mainly focused on capturing images of print abnormalities without taking other influencing factors, such as camera and part position, chamber illumination, and print geometry on the resolution of the captured images, into account. In this work, we present a scenario to evaluate and quantify the performance of an optical-based monitoring system in a Laser Powder Bed Fusion (LPBF) machine using the F1 score, considering factors such as scan vector orientation, part geometry (size) and position in a built chamber with a fixed camera position. The quantified results confirm that the F1 score can be used as a reliable means of evaluating the performance of optical-based monitoring systems in the LPBF process for the purposes of standardization. The biggest line width of the test artifact (1000 µm) had the highest F1 score range of 0.714–0.876 compared to the smallest (200 µm) with a 0.158–0.649 F1 score.

Transcriptional regulation of Satb1 in mouse trophoblast stem cells.

SATB homeobox proteins are important regulators of developmental gene expression. Among the stem cell lineages that emerge during early embryonic development, trophoblast stem (TS) cells exhibit robust SATB expression. Both SATB1 and SATB2 act to maintain the trophoblast stem-state. However, the molecular mechanisms that regulate TS-specific Satb expression are not yet known. We identified Satb1 variant 2 as the predominant transcript in trophoblasts. Histone marks, and RNA polymerase II occupancy in TS cells indicated an active state of the promoter. A novel cis-regulatory region with active histone marks was identified ∼21kbp upstream of the variant 2 promoter. CRISPR/Cas9 mediated disruption of this sequence decreased Satb1 expression in TS cells and chromosome conformation capture analysis confirmed looping of this distant regulatory region into the proximal promoter. Scanning position weight matrices across the enhancer predicted two ELF5 binding sites in close proximity to SATB1 sites, which were confirmed by chromatin immunoprecipitation. Knockdown of ELF5 downregulated Satb1 expression in TS cells and overexpression of ELF5 increased the enhancer-reporter activity. Interestingly, ELF5 interacts with SATB1 in TS cells, and the enhancer activity was upregulated following SATB overexpression. Our findings indicate that trophoblast-specific Satb1 expression is regulated by long-range chromatin looping of an enhancer that interacts with ELF5 and SATB proteins.

Analyzing TLS Scan Distribution and Point Density for the Estimation of Forest Stand Structural Parameters

In recent decades, the feasibility of using terrestrial laser scanning (TLS) in forest inventories was investigated as a replacement for time-consuming traditional field measurements. However, the optimal acquisition of point clouds requires the definition of the minimum point density, as well as the sensor positions within the plot. This paper analyzes the effect of (i) the number and distribution of scans, and (ii) the point density on the estimation of seven forest parameters: above-ground biomass, basal area, canopy base height, dominant height, stocking density, quadratic mean diameter, and stand density index. For this purpose, 31 combinations of TLS scan positions, from a single scan in the center of the plot to nine scans, were analyzed in 28 circular plots in a Mediterranean forest. Afterwards, multiple linear regression models using height metrics extracted from the TLS point clouds were generated for each combination. In order to study the influence of terrain slope on the estimation of forest parameters, the analysis was performed by using all the plots and by creating two categories of plots according to their terrain slope (slight or steep). Results indicate that the use of multiple scans improves the estimation of forest parameters compared to using a single one, although using more than three to five scans does not necessarily improves the accuracy. Moreover, it is also shown that lower accuracies are obtained in plots with steep slope. In addition, it was observed that each forest parameter has a strategic distribution depending on the field of view of the TLS. Regarding the point density analysis, the use of 1% to 0.1% (≈136 points·m−2) of the initial point cloud density (≈37,240.86 points·m−2) generates an R2adj difference of less than 0.01. These findings are useful for planning more efficient forest inventories, reducing acquisition and processing time as well as costs.

Rates of cortical thinning in Alzheimer’s disease signature regions: pathological influences and cognitive consequences in members of the 1946 British birth cohort

AbstractBackgroundConsistent patterns of reduced cortical thickness (so‐called signature regions) have been identified in early Alzheimer’s disease (AD), including in the pre‐dementia stages, but studies investigating the pathological underpinnings and cognitive consequences of longitudinal changes in these regions have been limited.Method337 cognitively normal participants (mean [SD] age 70.5 [0.6] years) underwent 18F‐florbetapir amyloid‐ß PET, volumetric MRI, and cognitive assessment as part of Insight 46, a sub‐study of the 1946 British birth cohort (Table 1 for characteristics). Baseline and follow‐up T1‐weighted MRI (mean [SD] interval 2.4 [0.2] years) were processed using Freesurfer’s longitudinal stream (v.7.1.0) and cortical thickness was derived in two AD signatures (Table 2 footnote for details). Linear regression was used to test whether rates of change in AD signature cortical thickness were influenced by baseline amyloid‐ß deposition (positive/negative status or continuous SUVR) or white matter hyperintensity volume (WMHV; a marker of presumed cerebrovascular disease), and whether they were related to longitudinal cognitive change as measured using the Preclinical Alzheimer Cognitive Composite (PACC). Covariates included sex, age at baseline scan, childhood cognition, educational attainment, and socioeconomic position. Interaction terms were added to test whether associations with longitudinal cognitive change differed by baseline amyloid‐ß status.ResultHigher baseline WMHV was associated with faster rates of cortical thinning in AD signature regions, but baseline amyloid‐ß status and SUVR were not (Table 2; Figure 1). There were differential effects of rates of change in AD signature cortical thickness by baseline amyloid‐ß status, whereby greater rates of AD signature cortical thinning predicted faster rates of PACC decline in amyloid‐ß positive participants only (Table 3; Figure 2).ConclusionCortical thinning in AD signature regions may arise via non‐amyloid‐ß pathways in cognitively normal elderly. However, the presence of amyloid‐ß may make individuals more susceptible to the effects of faster rates of cortical thinning in these regions (or vice versa) since these factors interact to influence rates of cognitive decline. These findings provide insight into processes that might underlie progression to dementia in later life and have implications for the utility of AD signature cortical thickness as a biomarker in the preclinical phase of AD.

Bridge Non-Destructive Measurements Using a Laser Scanning during Acceptance Testing: Case Study.

Owing to the recent proliferation of inventory works on roads and railways, bridge acceptance tests have increased exponentially. These tests' results are often misinterpreted owing to the use of various measuring equipment types, rendering integrated interpretation problematic. It is also problematic that adjusting the measurement method is difficult when the structure's response to load is uncertain. Therefore, it is important to observe the largest possible range of possible deformations. For this reason, the present study suggests a novel approach to bridge non-destructive measurements using a laser scanner during acceptance testing. The main advantage of our method is the ability it affords to observe all points of the structure during testing, an ability that is extremely important is the absence of unambiguous data regarding the bridge's condition. To significantly increase the scanning accuracy (up to 0.5 mm), measurements from a limited number of linear sensors are used (whose accuracy is up to 0.1 mm). To achieve optimal accuracy, we performed the following steps: first, we adapted the precision requirements to the numerical project. For this purpose, we used potentiometric sensors to measure linear deformations. Next, we performed laser scanning measurements from two scan positions. Finally, we filtered the data for the selected cross-section and modelled the points into polynomial deflection. The performed tests confirmed that the structure's response was as predicted by the FEM model, and the object was approved for use. Our future tests will be based on the selection of a structure with minimal measurement errors, and the results will be compared using a total station, ensuring the highest possible quality of service, which can be repeated in simple steps. As study objects, we presented two items: the first without proper calibration on a linear sensor and the second using linear sensors to present the highest possible accuracy of our experiment.

Direct Assimilation of Chinese FY-3E Microwave Temperature Sounder-3 Radiances in the CMA-GFS: An Initial Study

FengYun-3E (FY-3E), the fifth satellite in China’s second-generation polar-orbiting satellite FY-3 series, was launched on 5 July 2021. FY-3E carries a third-generation microwave temperature sounder (MWTS-3). For the first time, this study demonstrates that MWTS-3 radiances data assimilation can improve the China Meteorological Administration Global Forecast System (CMA-GFS). By establishing a cloud detection module based on the retrieval results of the new channels of MWTS-3, a quality control module according to the error characteristics of MWTS-3 data, and a bias correction module considering the scanning position of satellite and weather systems, the effective assimilation of MWTS-3 data in the CMA-GFS has been realized. Through one-month cycling experiments of assimilation and forecasts, the error characteristics and assimilation effects of MWTS-3 data are carefully evaluated. The results show that the observation errors in MWTS-3 data are similar to those in advanced technology microwave sounder (ATMS) data within the same frequency channel, are slightly larger than those in the advanced microwave-sounding unit-A (AMSU-A) data, and are much better than those in the MWTS-2 data. The validation of the assimilation and prediction results demonstrate the positive contribution of MWTS-3 data assimilation, which can remarkably reduce the analysis errors in the Northern and Southern Hemispheres. Specifically, the error growth on the upper layer of the model is obviously suppressed. When all other operational satellite observations are included, the assimilation of MWTS-3 data has a neutral or slightly positive contribution to the analysis and forecast results, and the improvement is mainly found in the Southern Hemisphere. The relevant evaluation results indicate that the MWTS-3 data assimilation has good application prospects for operation.

Performance of the correlated painting based on the mechanical structure of the anticorrelated painting scheme

The China Spallation Neutron Source (CSNS) accelerator consists of an 80 MeV ${H}^{\ensuremath{-}}$ Linac and a 1.6-GeV rapid cycling synchrotron (RCS). The painting scheme is one of the most important factors for the control of low beam loss at high beam power. In the painting injection of the CSNS/RCS, position scanning is used in both horizontal and vertical planes, and the anticorrelated painting is the design scheme. By using the anticorrelated painting, the beam power has successfully reached 50 kW. However, some problems have been found in the higher power beam commissioning, for instance, too large beam size after painting, nonuniform beam distribution, large transverse coupling effect, and so on, resulting in additional beam loss and making it difficult to satisfy the requirements of a high-power user mode. In order to solve these problems, flexibility in the CSNS design has been exploited to implement the correlated painting by using the rising current curve of the pulse power supply. The effectiveness of the new method has been verified in the simulation and beam commissioning, which can well control the full beam emittance and improve the beam distribution. By using the new method, the beam power on the target has successfully risen from 50 kW to the design value of 100 kW. Under the mechanical structure of the anticorrelated painting scheme where the position scanning is used in both horizontal and vertical planes, the correlated painting has been successfully achieved by using the rising current curve.

Different chest HRCT scan protocols change the extent of ground glass opacities

BackgroundGround glass opacity (GGO) is the main HRCT feature representing alveolitis in systemic sclerosis-associated interstitial lung disease (SSc-ILD), but may also represent other conditions such as atelectasis or edema. It is unclear how much this is affected by the HRCT scan protocol used. We aimed to compare the performance of three different HRCT protocols to evaluate the degree of SSc-ILD related changes.MethodsEleven patients with SSc underwent chest HRCT scan by three different protocols: First, a supine scan after lying down for 15 minutes, then two scans in alternating order: A prone position scan, and a supine position scan after performing 10 deep breaths using a positive expiratory pressure (PEP) device. The HRCT scans were evaluated by the Warrick score system for ILD-related findings.ResultsThe three HRCT protocols were compared and resulted in different mean (95% CI) Warrick scores: 9.4 (5.3–13.4) in supine after rest; 7.5 (95% CI 3.8–11.1) in prone and 7.6 (95% CI 4.2–11.1) in supine after PEP. When comparing supine after rest to prone and supine after PEP, the latter two scans had a significantly lower score (p = 0.001 for both comparisons). In all cases, only sub-scores for ground glass opacities differed, while sub-scores for fibrosis-related changes did not change.ConclusionsDifferent HRCT scan protocols significantly altered the Warrick severity score for SSc-ILD findings, primarily because of changes in ground glass opacities. These differences may be clinically meaningful.

Adaptive point-scan imaging beyond the frame rate–resolution limit with scene-reactive scan trajectories

Point-scanned imaging modalities such as optical coherence tomography (OCT) are subject to frame rate limits governed by the image resolution, sampling rate, and scanner dynamics. For scenes with dynamic features on static backgrounds, adaptive scanning escapes these limits by visiting scan positions only as needed. We implemented adaptive scanning using a probabilistic approach that balanced re-imaging of known dynamic positions with exploration for undiscovered ones. We evaluated our approach in model systems that simulated multitarget tracking and ophthalmic surgery using a swept-source OCT system. We demonstrated frame rate speedups in excess of 5 × without degradation in image quality, a performance that would have otherwise required a significantly faster source.

GSOR11 Presentation Time: 9:55 AM: 3D Printing Enhanced GYN Brachytherapy: From Novice to Expert in One Print with the TARGIT-FX

<h3>Purpose</h3> It is well established in cervical brachytherapy that the addition of interstitial (IS) needles to intra-cavitary (IC) applicators can significantly enhance dosimetry by improving target coverage without increasing normal tissues doses. Accurate placement of interstitial needles requires significant technical skill and imaging guidance proficiency, thereby limiting the benefits to a subset of practitioners and patients. Available commercial combined IC/IS applicators restrict the available needle positions to often unsatisfactory locations for optimized dosimetry. We have developed and further improved our supplemental templates that attach to the tandem applicator and guides needles to optimized positions for different tumor topologies. This new TARGIT-FX (Tandem Anchored Radially Guiding Interstitial Template - Flexible eXtended) is 3D printed from biologically compatible materials, can be steam sterilized and provides multiple degrees of flexibility to simplify and facilitate interstitial needle insertion. <h3>Materials/Methods</h3> Our previously described IS needle guide (TARGIT), which facilitates placement of complementary needles in a tandem and ovoid implant, was redesigned with the purported goal of added flexibility and ease of use. The tandem attached small template was extended all the way to the vaginal introitus to allow needle insertion from outside the patient. The number of needle position options increased from four to nine to better cover a wider range of clinical situations: three paired width options ((2.0, 1.5 and 1.25 cm width) at the level of point A and three individual posterior locations (figure, insert E). The new design has been used clinically for 14 different patient implants During the procedure, the tandem is first inserted (Figure 1A), the TARGIT-FX is then slid over in position and secured over the tandem (Fig. 1B-C); after the ovoids are placed, needles can be inserted from outside the patient in the selected locations as clinically required (Fig. 1 D). Figure 1E show all the needle potential positions. The procedure time and relevant dosimetric parameters were tracked, as well as usability. <h3>Results</h3> The procedure time with the TARGIT-FX was decreased to 24 min from a benchmark of 29 min with the older TARGIT design (average over 68 implants). The V100% remained similar with 92.2% as compared to the 90.2% TARGIT benchmark, while organs at risk remained within constraints. The main goals of flexibility were achieved as follows: the larger number of needle positions enabled greater customization and live changes during the procedure based on the patient anatomy as visualized on live transrectal ultrasound. The ease of use, in particular the ability to reliably insert and position needles from outside the patient, enabled our medical residents under supervision to confidently perform the entire combined IS/IC implants and even first fraction implants. In addition, the new design enabled in one particular case the addition of a needle after the initial procedure, following the planning CT, as the needle could be inserted from outside with the patient lying on the CT table in scanning position. The reliability and consistency of needle placement with the new design may further increase speed since ultrasound imaging during the procedure may be reduced or omitted. <h3>Conclusion</h3> The 3D printed TARGIT-FX enables simple, fast and reliable interstitial needle insertion for combined tandem and ovoid and IS implants. The flexibility of the design enables new or less experienced users to improve the degrees of freedom and dosimetry of their combined IC/IS implants.

Evaluation and prediction method of automotive electronic accelerator pedal based on support vector regression

In the process of automobile electronic accelerator pedal development, it is a critical and challenging issue to evaluate the rationality and comfort of the design of an automotive electronic accelerator pedal. Many factors influence the comfort of the accelerator pedal, such as the spatial layout, dynamic characteristics, and matching characteristics of the accelerator pedal and vehicle motion. Since comfort evaluation requires a lot of manpower and material resources, this paper proposes a prediction model based on support vector machine regression algorithm (SVR) for comprehensive evaluation of Chinese passenger car pedals. It uses the known evaluation results to predict the unknown evaluated accelerator pedal parameters to achieve a more efficient and accurate assessment of electronic accelerator pedal design. Firstly, the article performs pedal position scans, pedal static, and road tests to give criteria, limitations, and recommended design ranges for pedal operation. Then, the vehicle performance was predicted and evaluated using a support vector machine prediction model and back propagation (BP) neural network prediction model for comparison. The correlation coefficient for the prediction results of the SVR model was 0.9024 with a mean square error was 0.00195. The correlation coefficient for the BP neural network model prediction result was 0.8694 with a mean square error of 0.00582. Finally, the simulation results were analyzed, and the results showed that support vector regression outperformed the neural network in predicting the validity and reliability of pedal design and performance evaluation, and can facilitate automotive pedal design and development.

Internal calibration for opportunistic computed tomography muscle density analysis.

Muscle weakness can lead to reduced physical function and quality of life. Computed tomography (CT) can be used to assess muscle health through measures of muscle cross-sectional area and density loss associated with fat infiltration. However, there are limited opportunities to measure muscle density in clinically acquired CT scans because a density calibration phantom, allowing for the conversion of CT Hounsfield units into density, is typically not included within the field-of-view. For bone density analysis, internal density calibration methods use regions of interest within the scan field-of-view to derive the relationship between Hounsfield units and bone density, but these methods have yet to be adapted for muscle density analysis. The objective of this study was to design and validate a CT internal calibration method for muscle density analysis. We CT scanned 10 bovine muscle samples using two scan protocols and five scan positions within the scanner bore. The scans were calibrated using internal calibration and a reference phantom. We tested combinations of internal calibration regions of interest (e.g., air, blood, bone, muscle, adipose). We found that the internal calibration method using two regions of interest, air and adipose or blood, yielded accurate muscle density values (< 1% error) when compared with the reference phantom. The muscle density values derived from the internal and reference phantom calibration methods were highly correlated (R2 > 0.99). The coefficient of variation for muscle density across two scan protocols and five scan positions was significantly lower for internal calibration (mean = 0.33%) than for Hounsfield units (mean = 6.52%). There was no difference between coefficient of variation for the internal calibration and reference phantom methods. We have developed an internal calibration method to produce accurate and reliable muscle density measures from opportunistic computed tomography images without the need for calibration phantoms.