Planar Measurements Research Articles

Investigating the impact of end-capped acceptor alterations to dimethyl fluorene-based hole transporting material for perovskite solar cells

Hole-transporting materials (HTMs) could boost the proficiency of third generation-perovskite solar cells since they have ultrafast charge mobility that improves optoelectronic and photovoltaic attributes. Five new H-shaped molecules were sketched using thiophene bridged, end-capped acceptor alteration on a dimethyl fluorene core-based molecule. Planarity measurements, absorption spectra, frontier molecular orbitals (FMOs), excitation energy (Ex), density of states (DOS), molecular electrostatic potentials (MEPs), transition density matrix (TDM), exciton binding energy, interaction coefficient, hole-electron overlap, open circuit voltage, fill factor, and power conversion efficiency were analyzed via DFT/MPW1P9W1/6-31G (d,p) for evaluating performance of perovskite solar cells. All newly sketched molecules with an A-π-D-π-A skeleton exhibited outstanding optoelectronic properties, including broader absorbance (563–740 nm) in chlorobenzene, indicating better solution processing. Lower band gaps (2.08–2.72 eV) than reference (3.78 eV) indicated efficient electron density transfer. Increased open-circuit voltage (1.55–2.02 eV) along with lower reorganization energies of the electron (0.043249–0.122527 eV) and hole (0.108105–0.148322 eV) lead to effective charge transport capabilities. Higher dipole moments indicated suitable film fabrication. A higher fill factor (0.9166–0.9325) and power conversion efficiency (34.31–45.49 %) led to an improved performance. Concisely, all the newly sketched molecules showed redshifted absorbance, narrower band gaps, deeper HOMO energies, improved charge transfer, higher softness, and smaller hardness values when compared to ZR, which confirms their superiority as future dopant-free HTM for PSCs.

Increased lateral femoral condyle ratio measured by MRI is associated with higher risk of solitary meniscus injury.

Background: Past studies found that an increased lateral femoral condyle ratio is associated with anterior cruciate ligament injuries, but it is not clear if there is a link between MRI-measured lateral femoral condyle ratios and meniscal injuries. MRI provides a more accurate selection of measurement planes. Compared to X-rays, it further reduces data errors due to non-standard positions. Objective: To study the relationship between knee bone morphology and Solitary meniscal injuries by MRI. Methods: A total of 175 patients were included in this retrospective case-control study, including 54 cases of pure medial meniscus injury, 44 cases of pure lateral meniscus injury as the experimental group, and 77 control subjects. MRI images were used to measure the femoral notch width, femoral condylar width, femoral notch width index, lateral femoral condylar ratio (LFCR), posterior tibial slope, medial tibial plateau depth, and meniscus slope. In addition, carefully check for the presence of specific signs such as bone contusions and meniscal extrusions. Comparing the anatomical differences in multiple bone morphologies between the two groups, a stepwise forward multifactorial logistic analysis was used to identify the risk factors for Solitary meniscal injuries. Finally, ROC curves were used to determine the critical values and best predictors of risk factors. Results: MTS, LTS, and LFCR ended up as independent risk factors for meniscus injury. Among all risk factors, LFCR had the largest AUC of 0.781 (0.714-0.848) with a threshold of 72.75%. When combined with MTS (>3.63°), diagnostic performance improved with an AUC of 0.833 (0.774-0.892). Conclusion: Steep medial tibial plateau slope, steep lateral tibial plateau slope angle, and deep posterior lateral femoral condyles on MRI are independent risk factors for meniscal injuries. In patients with knee discomfort with the above imaging findings (X-ray, MRI), we should suspect and carefully evaluate the occurrence of meniscal injuries. It not only provides a theoretical basis to understand the mechanism of meniscus injury but also provides theoretical guidance for the prevention of meniscus injury and the development of intervention measures. Level of evidence III.

Improved planar near-field measurement based on data assimilation

The planar near-field measurement is widely used for antenna radiation testing because of its compact test space. However, due to the inevitable truncation error in the practical test, the measured radiation pattern of the antenna under test (AUT) is accurate only within certain confidence (angular) interval. In order to improve the measurement accuracy outside the confidence interval, this paper proposes an improved method of planar near-field measurement based on data assimilation. A reasonable mathematical model for the AUT radiation pattern is established so that the simulation data and the practical test data are fused with improved accuracy. The effectiveness of the proposed method for parameter selection has been verified experimentally, compared with the conventional method. In addition, the proposed method indicates a universal approach of complementing the measurement data with simulations or other data sources for improved accuracy.

Online measurement method for dimensions of disk parts based on machine vision.

Online measurement of disk part dimensions by the standard industrial camera features low cost, high efficiency and good universality, but the impact of projection distortion and end face chamfer on measurement is needed to overcome. Present work presents a measurement method to resolve above issues based on machine vision. To improve the measurement accuracy, lower end face of a disk part is determined as calibration plane and the upper end face is measurement plane. To reduce the impact of projection distortion and chamfer on measurement, the measurement points are reconstructed on the measurement plane by re-projection. Then, the inner and outer diameters of disk parts are measured by circle geometric fitting, and the thickness is calculated by the measurement plane position. The experimental results show that the method can online measure disk part dimensions just by a single image, and accuracy meets the requirements of universal grade disk parts.

Comparative study on the complex behaviour of flow fields in a transparent non-axisymmetric corotating system between two arm-insertion angles at two measurement planes in an enclosure

Comparative study on the complex behaviour of flow fields in a transparent non-axisymmetric corotating system between two arm-insertion angles at two measurement planes in an enclosure

Planar Near-Field Antenna Measurements with a Uniform Step Larger than Half-Wavelength

Planar Near-Field Antenna Measurements with a Uniform Step Larger than Half-Wavelength

Alveolar bone retention following treatment of dilacerated labial inversely impacted maxillary central incisors-a retrospective study.

The root of late-dental-age labial inversely impacted maxillary central incisors (LIIMCIs) typically develops to severe dilacerated morphology. Therefore, reliable posttreatment periodontal estimates of orthodontic treatment prognosis would be critical to the treatment value of impacted incisors. This study aims to analyze further changes in dimensions of the alveolar bone following the closed-eruption treatment of late-dental-age dilacerated LIIMCIs. Cone beam computed tomography (CBCT) scanning data of 16 patients with unilateral dilacerated late-dental-age LIIMCIs were collected, including the pretreatment (T1) and at the 2.23 ± 0.78 years follow-up stage (T2) respectively. Patients underwent closed-eruption treatments to bring the impacted incisor into the dental arch. Dolphin imaging software was used to measure alveolar bone height labially, palatally, and proximally to the site at T1 and T2, as well as alveolar bone thicknesses at 0, 2, 4, 6 and 8 mm below the initial measurement plane (IMP). The alveolar bone heights on the impacted and contralateral sides increased from T1 to T2 (p < 0.05). Alveolar bone growth on both sides had no significant difference. In T2, the mean values of labial and distal alveolar heights on the contralateral sides were greater than on the impacted sides (p < 0.05). The mean values of total alveolar bone thicknesses on the impacted sides in T1 were significantly smaller than those on the contralateral sides in IMP-0, 2, 4, 6, 8 (p < 0.05). The total thicknesses on the impacted sides in T2 increased and were significantly greater than on the contralateral sides (p < 0.05), except for the thickness in IMP-0. The closed-eruption treatment of dilacerated late-dental-age LIIMCIs results in no significant changes to alveolar bone height, except on the labial and distal sides, with increased alveolar bone thickness, suggesting that this approach may be viable first choice therapy for non-extraction orthodontic cases.

Fourier bases of a class of planar self-affine measures

Fourier bases of a class of planar self-affine measures

Classification and sizing of surface defects of pipelines based on the results of complex diagnostics by ultrasonic, eddy current and visual and measuring methods of nondestructive testing

The issues of classification and determination of parameters of surface operational defects according to the results of ultrasonic, eddy current and visual and measuring methods of nondestructive testing are considered. At the same time, the visual and measuring method was realized with the use of a television inspection camera equipped with a computer vision function and a laser triangulation sensor. The paper presents a dataset containing 5760 images of pipelines with and without pitting corrosion. A convolutional neural network (CNN) is presented, which has been applied to classify the images obtained from a TV inspection camera into images without corrosion and images with pitting corrosion. The paper presents a dataset containing 269 measurements of planar and volumetric surface defects. A model for surface defect sizing based on gradient boosting is presented. The paper develops an algorithm for classification and sizing of surface defects in complex diagnostics, in which the obtained models are applied, and determines the accuracy of this algorithm by the RMSE metric, which was calculated within the studying test data set and amounted to 0.011 mm.

Effect of filament length on the flow field of a rotationally oscillating cylinder with an attached filament

Experimental studies are conducted to examine the effect of filament length on the flow field and forces in the flow past a rotationally oscillating cylinder with an attached filament. The diagnostics are flow visualization through planar laser-induced fluorescence technique and characterization of the velocity and vorticity field using planar particle image velocimetry measurements. The streamwise force is estimated through control volume analysis, using an improved expression, described in Sunil et al., J. Fluid Mech. 930, A3 (2022). With an increase in the filament length, the wake structure transitions from a Kármán wake to a reverse Bénard–Kármán wake and subsequently to an asymmetric wake. This happens at a Strouhal number of StA = 0.25 and 0.6, respectively. The transition from a Kármán wake to a reverse Kármán wake precedes the drag-to-thrust transition. Thrust generation is observed to be a function of both the cylinder forcing parameters and the filament length. Shorter filaments (L/D = 0.5 and 1) produce drag, whereas longer filaments (L/D = 2, 3, and 4) produce thrust at FR≥ 2.5. Normalized values of circulation scale well with the filament length, L, and the filament tip velocity, VTE, in the case of longer filaments. The effect of filament length on vortex dynamics and thrust generation is examined through a time evolution of the instantaneous vorticity, velocity, and kinetic energy data. Maximum momentum and kinetic energy content is observed in the flow field near the instants when the vortices are shed in the wake.

High-resolution turbofan intake flow characterization by automated stereoscopic-PIV in an industrial wind tunnel environment

Unsteady inlet flow distortion can influence the stability and performance of any propulsion system, in particular for more novel, short and slim intakes of future aero-engine configurations. As such, the requirement for measurement methods able to provide high spatial resolution data is important to aid the understanding of these flow fields. This work presents flow field characterisations at a crossflow plane within a short aeroengine intake using stereoscopic particle image velocimetry (SPIV). A series of tests were conducted across a range of crosswind and high angle of attack conditions for a representative short and slim aspirated intake configuration at two operating points in terms of mass flow rate. The velocity maps were measured at a crossflow plane within the intake at an axial position L/D = 0.058 from where a fan is expected to be installed. The diameter of the measurement plane was 250 mm, and the final spatial resolution of the velocity fields had a vector pitch of 1.5 mm which is at least two orders of magnitude richer than conventional pressure-based distortion measurements. The work demonstrates the ability to perform robust non-intrusive flow measurements within modern intake systems in an industrial wind tunnel environment across a wide range of operating conditions; hence, it is suggested that SPIV can potentially become part of standard industrial testing. The results provide rich datasets that can notably improve our understanding of unsteady distortions and influence the design of novel, closely coupled engine-intake systems.

Comparison of Rapid Arc and Intensity Modulated Radiotherapy in a True Beam Linear Accelerator for 6 MV: Application of AAPM TG‐119 tests in treatment planning and quality assurance

AbstractObjectiveWe developed rapid arc (RA) and intensity‐modulated radiotherapy (IMRT) plans based on the American Association of Physicists in Medicine Task Group‐119 (AAPM TG‐119) proposals and compared the planning and quality assurance results.Materials and MethodsTwo treatment plans were used for each study patient: one using 7–9 IMRT fields and the other using the two full‐arc RA methods. Plan optimization and dose calculations were performed using 6 MV photons and EclipseTM with the anisotropic analytical algorithm (AAA). Task group (TG)‐119 described the planning objectives used to evaluate the treatment plans generated for this study. Point dose, planar fluence measurement, and trajectory log file analysis are used for quality assurance.ResultsThe conformity index (CI) for treatment plans varied between 0.76–0.91 when using IMRT and 0.75–0.93 when using RA. The homogeneity index (HI) was approximately 0.10–0.24 (IMRT) and 0.07–0.23 (RA). The ratio of the total number of monitor units required for IMRT to that required for RA was between 0.87 and 2.14. The treatment log files exhibited higher gamma passing with RA than with IMRT.ConclusionRA plans were more effective than IMRT plans in achieving the test goals. Point dose measurements and electronic portal imaging device (EPID)‐based planar fluence measurements showed statistically insignificant differences between the IMRT and RA plan quality assurance (QA) results. However, the trajectory log file analysis exhibited better gamma‐passing results for RA than for IMRT.

Error analysis of precision measurement with monocular vision

To systematically study the measurement error of the calibration coefficient method when the camera’s optical axis is not perpendicular to the measurement plane, this paper first discusses the principle of error measurement with 2D imaging model, and then derives the distribution relationship of physical points corresponding to evenly distributed pixels in the pixel coordinate system based on the projection transformation matrix of the vision system. Theoretical analysis reveals an equivariance series in the expression of physical point intervals. Considering rotational symmetry of the coordinate axis, this paper analyzes the geometric relationship when the calibration plane rotates around the axis and derives the mathematical expression for dimensional measurement. Finally, an experimental platform with both industrial and telecentric lenses is proposed and designed. Experimental results demonstrate that the measurement results of the expression derived in this paper are consistent with the traditional coordinate transformation method and the maximum deviation of the measurement is less than 0.06 mm, validating the theoretical analysis presented in this paper and providing theoretical guidance for subsequent practical application.

Model Verification and Experimental Study of The Turbomachinery Wake Flow Field Reconstruction

Abstract A clear understanding of the turbomachinery wake flow field is one of the key problems in developing turbomachinery aerodynamics. The theoretical model of helical vortices is established in cylindrical coordinates (r,θ,z), and the model corresponds to the experimental scheme, which verifies the feasibility of reconstructing flow field by interpolation in r-z plane under different θ. This model shows that theta should not exceed 20 degrees in order to reconstruct the flow field more accurately. Taking rotors as the representative of the turbomachinery, Particle image velocimetry (PIV) is used to measure the velocity field in the rotor wake. Interpolating reconstruction of spacing between different measurement planes, the reconstruction results are relative to the theory, which plane spacing should be less than 20 deg. Using the vorticity weighted average method to calculate the central position of the vortex core, the wandering motion of the tip vortex is obtained. On this basis, a correct conditional average algorithm is proposed to eliminate this effect. Through the analysis method of the circulation, it is proved that the point where the second derivative of the circulation with respect to the radius is 0 corresponds to the radius of the vortex core, and the evolution law of the growth of the vortex core radius is proportional to the square root of the vortex ages. The results provide a reliable experimental method for the quantitative study of the spatio-temporal evolution of complex vortex structures in the three-dimensional flow of turbomachinery wakes.

Position measurement technology of boom-type roadheader based on binocular vision

Positioning of underground mining equipment in coal mines is a primary challenge in the intelligent development of tunnel excavation. Accurate and reliable position measurement plays a crucial role in improving excavation efficiency. However, the stability and accuracy of traditional measurement methods are difficult to guarantee due to factors such as vibration, magnetic interference, and the absence of GPS signals in coal mine environments. To address the problem of unstable measurement of the boom-type roadheader‘s position, this paper proposes a binocular vision-based measurement technique that utilizes four light spots as characteristic points. By processing the target images captured by the binocular camera and combining the minimum bounding rectangle and ellipse fitting of the spot regions, the method successfully obtains the four light spot characteristics. Subsequently, precise matching and stereo distance measurement of the target in the left and right images enable the determination of the boom-type roadheader’s posi-tion information. A positioning platform based on binocular vision is built and experimentally evaluated. The results demonstrate that this method can achieve accurate spot extraction and stable measurement of the machine’s position, even in complex backgrounds such as mixed lighting and low illumination. The planar measurement errors within a distance range of 50 m are all within ±25 mm, which basically meets the required construction precision for tunnel excavation.

A Comprehensive Review of Optical Systems for Soot Volume Fraction Measurements in Co-Flow Laminar Flames: Laser-Induced Incandescence (LII) and Laser Extinction Method (LEM)

ABSTRACT Laser-Induced Incandescence (LII) has been widely acknowledged as a highly effective method for measuring soot in co-flow laminar flames. Conversely, quantitative assessments of soot volume fraction (SVF) are achievable through the Laser Extinction Method (LEM). This comprehensive review centers on the optical systems and experimental parameter configurations employed in LII and LEM measurements. Subsequently, several pivotal parameters specific to LII and LEM, such as laser fluence and detection wavelength, are individually discussed. Furthermore, this review showcases current experimental arrangements utilized for LEM measurements. In addition, recommendations are provided for the execution of planar LII and LEM measurements. Lastly, a summarized analysis and discussion pertain to an optical system capable of jointly measuring LII and LEM.

Laser absorption tomography based on unstructured meshing

Laser absorption tomography is an imaging technique used to monitor gas flow and combustion processes. The measurement plane is typically discretized using square pixels in which the flow field is assumed to be uniform. This approach can introduce large discretization errors compared to a finite element mesh with linear interpolation, especially when the domain has an irregular and non-rectangular boundary. In this work, we assess the influence of triangular mesh and quadrilateral mesh schemes on reconstruction accuracy. Our theoretical analysis and numerical studies demonstrate that linear interpolation yields superior performance compared to the conventional uniform-pixel method, and the error can be reduced from 0.250 to 0.097 and 0.160 to 0.105 for triangular and quadrilateral meshes, respectively. Non-body-fitted mesh can increase error by 70 % –99 % . The experiment also proves the superiority of body-fitted meshes with linear interpolation. Moreover, triangular mesh exhibits better noise immunity than quadrilateral mesh. The reconstruction quality appears to be insensitive to the mesh quality for the quadrilateral mesh.

Validation of Filtered Rayleigh Scattering Optical Rake Measurement Techniques in Turbomachinery Applications and Boundary Layers

Abstract Filtered Rayleigh scattering (FRS) is a non-intrusive, laser-based optical technique for measuring three-component velocity, static temperature, and static density with high spatial resolution and low uncertainty. FRS can be used to derive total values as well as turbomachinery efficiencies. The Virginia Tech team has been developing this seedless technique for simultaneous planar (or line) measurements to overcome the limitations associated with seed-based laser measurement techniques such as laser Doppler velocimetry (LDV), particle image velocimetry (PIV), and Doppler global velocimetry (DGV) as well as limitations with physical probe rakes such as blockage and wake production. This technique is especially attractive in flow cases or environments where the aforementioned seed-based laser measurement techniques are limited or not possible. A combination of specially designed boundary layer total pressure probe rake measurements, FRS optical rake measurements, and computational fluid dynamics (CFD) results in the inlet of a Honeywell TFE731-2 turbofan are presented. Results show that all three techniques (FRS, probe, and CFD) match within approximately 2% root-mean-square error (RMSE). Inlet efficiency was derived and found to be within 2.3% difference for all three techniques.

Automatic biometry of fetal brain MRIs using deep and machine learning techniques

Linear biometric measurements on magnetic resonance images are important for the assessment of fetal brain development, which is expert knowledge dependent and laborious. This study aims to construct a segmentation-based method for automatic two-dimensional biometric measurements of fetal brain on magnetic resonance images that provides a fast and accurate measurement of fetal brain. A total of 268 volumes (5360 images) magnetic resonance images of normal fetuses were included. The automatic method involves two steps. First, the fetal brain was segmented into four parts with a deep segmentation network: cerebrum, cerebellum, and left and right lateral ventricles. Second, the measurement plane was determined, and the corresponding biometric parameters were calculated according to clinical guidelines, including cerebral biparietal diameter (CBPD), transverse cerebellar diameter (TCD), left and right atrial diameter (LAD/RAD). Pearson correlation coefficient and Bland–Altman plots were used to assess the correlation and agreement between computer-predicted values and manual measurements. Mean differences were used to evaluate the errors quantitatively. Analysis of fetal cerebral growth based on the automatic measurements was also displayed. The experiment results show that correlation coefficients for CBPD, TCD, LAD and RAD were as follows: 0.977, 0.990, 0.817, 0.719, mean differences were − 2.405 mm, − 0.008 mm, − 0.33 mm, − 0.213 mm, respectively. The correlation between the errors and gestational age was not statistically significant (p values were 0.2595, 0.0510, 0.1995, and 0.0609, respectively). The proposed automatic method for linear measurements on fetal brain MRI achieves excellent performance, which is expected to be applied in clinical practice and be helpful for prenatal diagnosis and clinical work efficiency improvement.

Investigation of the wake region behind a hemispherical turret via laser Rayleigh scattering.

Planar and volumetric density measurements in the wake region behind a mounted hemispherical turret are obtained using laser Rayleigh scattering. The measurements are conducted in a Mach 2 wind tunnel facility at the Kirtland Air Force Base. Quantitative measurements of density and contour plots with lines of constant density are computed, thus enabling visualization of the turret wake's fluid dynamics. A new, to the best of our knowledge, laser diagnostic methodology and configuration for capturing laser images is also presented. This methodology enables further suppression of background light scattering. Multi-dimensional single-shot and time-average measurements are recorded at multiple axial locations behind the turret. The images acquired reveal turbulent regions of the wake flow, and a discussion of the observed phenomena is presented.