Angle Measurement Method Research Articles

Micro-CT analysis of the internal acoustic meatus angles as a method of sex estimation in skeletal remains.

The aim of the present study was to verify the lateral angle method for sex estimation by using computed micro-tomography. Two measurements of the anterior lateral angle of the internal acoustic meatus were assessed. The performed analysis revealed that the mean angle at the level of transverse crest of the fundus of the internal acoustic meatus in adults is significantly greater in females (45.58° vs. 39.68°; p < 0.05). A 45° sectioning point was applied, and sex allocation using this measurement was correct in 81.81% of adult samples. In turn, when utilizing the measurement at the level of modiolus of the cochlea, we did not obtain a satisfactory result in sex classification (59.09%). In subadults (male and female samples), the anterior lateral angles were undifferentiated. Thus, the conducted micro-CT analysis shows that the anterior lateral angle measurement method can be used as a preliminary indication of sex in adult individuals.

Simultaneous Measurement of Absolute Distance and Angle Based on Dispersive Interferometry

We present a dispersive interferometry of optical frequency comb for simultaneous measuring absolute distance and angle. The reconfigured Michelson interferometer can emit two parallel measured beams and one reference beam. The three pulse beams interfere with each other, and the interference spectrum is sampled by a spectrometer. It is simultaneously modulated by the three optical path differences, which contains the information of absolute distance and angle and can be demodulated by a Fourier transform. By making an angle measurement comparison with a calibrated turntable, the proposed method shows that the obtained mutual agreement is better than 3 arcsec in the range of ± 5°. The commercial interferometer and autocollimator are used to verify the feasibility of the proposed method for precision distance and angle measurement.

Dynamic balancing of a two-plane rotor without phase angle measurement using the amplitude subtraction method

Two-plane balancing is required on a rotor where the length is greater than the diameter. Balancing such a rotor is tricky, since the effects of unbalanced forces on both of the planes need to be considered when determining the corrective action. This paper presents a method of dynamic balancing for a two-plane rotor without the need to measure the phase angle. The rotor is balanced by measuring vibration amplitudes at the support bearing of the rotor shaft. A new rotor balancing method of amplitude subtraction is used to calculate the balancing weights and their positions on the rotor. The advantages of this method over the phase angle measurement method are also discussed in the paper.

Study on a smart cross-polarization interference method to the polarized integration mono-pulse array radar

In order to effectively interfere with radar in the complex electronic countermeasure environment, this paper studies the cross-polarization interference method to the polarized integration mono-pulse array radar based on the radar antenna’s intrinsic property that it can receive the cross-polarization components. Firstly, the polarized integration mono-pulse angle measurement method of array radar is described. Then, the cross-polarization interference method for the polarized integration mono-pulse array radar is theoretically analysed, and it is proved mathematically that this interference method can bring the error term, leading to a decrease in measurement accuracy. Finally, a variant function of the singular function’s derivative is proposed to simulate the cross-polarization pattern of the sub-array. On this basis, the cross-polarization interference on the polarized array radar angle measurement performance is simulated, and the performance curve is obtained. The simulation results show that the cross-polarization interference can lead to a decrease in the angle measurement performance, and when the cross-polarization interference component is close to the echo co-polarization component, the interference effect is good. The power requirement for implementing the interference is low, so it is conveniently implemented in various confrontational situations. This provides an effective and easy-to-use smart radar polarization interference method for electronic countermeasures.

Validity and Reliability of the WIMUTM Inertial Device for the Assessment of Joint Angulations.

Range of motion measurement is fundamental in the physical examination and functional evaluation of different joints. WIMUTM is an inertial device that allows the analysis of joint motion easily in real time. This study had a two-fold goal: (i) to evaluate the validity of WIMUTM on the measurement of different angle positions, compared with a standard goniometer and 2D video-based motion analysis software; and (ii) to evaluate the use of WIMUTM in the assessment of angulations in a joint, specifically assessing the validity and reliability of WIMUTM on the measurement of ankle dorsiflexion, compared to a standard goniometer and Kinovea. The intraclass correlation coefficient and Pearson´s correlation coefficient (r) were performed to calculate the concurrent validity, and Bland-Altman plots were performed to analyze agreement between measures. For the analysis of reliability, both relative and absolute indices were used. The results showed excellent validity and reliability of WIMUTM in the assessment of angle positions and ankle dorsiflexion. The current findings conclude that WIMUTM is a valid and reliable instrument to measure angle and joint motions. In short, WIMUTM provides a new clinical and sportive method of angle measurement.

Evaluation of measurement uncertainty for a high-precision angle comparator with a vacuum preloaded structure

Angle measurement is widely used in various fields of science and technology. With the development of technology, the measurement uncertainty of angle metrology becomes more and more demanding. To achieve high-precision calibration of a high-precision angle comparator with a sub-arc-second level, a method of angle position error calibration and measurement uncertainty evaluation based on no material reference was established. Firstly, the structure of the angle comparator with a vacuum preloaded air bearing driven by an ultrasonic motor drive and the construction of the whole calibration system are briefly introduced. Then, the basic principle, algorithm and error separation principle of angle calibration based on the optical angle measurement method were studied, and the test process is introduced. Finally, the measurement results and error sources were analyzed, the measurement uncertainty model was established and the measurement uncertainty was evaluated. The experimental results show that the high-precision angle comparator with a vacuum preloaded structure has an angle position error of 0.12″ and a measurement uncertainty of 0.05″ (k = 2). Through many experiments, it is shown that the measurement system has a stable high-precision calibration capability with a sub-arc-second level for circular division artifacts.

Automatic Anterior Chamber Angle Measurement for Ultrasound Biomicroscopy Using Deep Learning.

To develop a software package for automated measuring of the trabecular-iris angle (TIA) using ultrasound biomicroscopy. Ultrasound biomicroscopy images were collected and the TIA was manually measured by specialists. Different models were used as the convolutional neural network for the automatic TIA measurement. The root-mean-squared error, explained variance, and mean absolute percentage error were used to evaluate the performance of these models. The interobserver reproducibility, coefficient of variation, and intraclass correlation coefficient were calculated to evaluate the consistency between the manual measured and the model predicted values. ResNet-18 had the best performance in root-mean-squared error, explained variance, and mean absolute percentage error among all 5 models. The average difference between the angles measured manually and by the model is -0.46±3.97 degrees for all eyes, -1.67±5.19 degrees for open angles, and 0.75±1.43 degrees for narrow angles. The coefficient of variation, intraclass correlation coefficient, and reproducibility of the total TIA measurements are 6.8%, 0.95, and 6.1 degrees for all angles; 6.4%, 0.99, and 7.7 degrees for open angles; and 8.8%, 0.93, and 4 degrees for narrow angles, respectively. Preliminary results show that this fully automated anterior chamber angle measurement method can achieve high accuracy and have good consistency with the manual measurement results, this has great significance for future clinical practice.

A New Optical Angle Measurement Method Based on Second Harmonic Generation with a Mode-Locked Femtosecond Laser

This paper proposes a new optical angle measurement method based on second harmonic generation with a mode-locked femtosecond laser source by taking use of the unique characteristic of high peak power and high-intensity electric field of the femtosecond laser pulses. The angle is measured from the second harmonic wave intensity, which is a function of the angle between the laser beam axis and the optic axis of a nonlinear crystal attached to the target of interest. It is found that the beta barium borate (BBO) crystal is suitable as the nonlinear crystal for this purpose through theoretical simulation. As the first step of research, an experimental demonstration is also carried out in such a way that a change of the second harmonic wave intensity due to the angular displacement of BBO crystal is measured to verify the feasibility of the proposed principle of the angle measurement method.

Comparison of two methods for subpubic angle measurement from reconstructed three-dimensional pelvic model

BackgroundSex estimation using the subpubic angle of the pelvis is highly accurate for identification of unknown skeletonized remains. This study compared two methods for measuring the subpubic angle from reconstructed three-dimensional (3D) pelvic models. The aims were to quantify the differences in the subpubic angle measurement by Checkpoint (Method 1) and MeshLab + OnScreenProtractor (Method 2), to determine the 95% limits of agreement and to identify any measurement bias. Multislice computed tomography (MSCT) scans of 85 individuals were used in this study. The MSCT scans were performed on a Siemens SOMATOM Sensation 64 scanner (Siemens Germany Ltd.). Segmentation of the MSCT scans was performed using 3D Slicer to reconstruct 3D pelvic models. Subpubic angle was measured on Checkpoint using four landmarks (Method 1), and with OnScreenProtractor on MeshLab (Method 2).ResultsThe intraclass correlation coefficient (ICC) showed a high correlation between repeated measurements in both methods. Subpubic angle measurements by Method 1 and Method 2 were significantly different (p < 0.05). Method 2 (M = 82.2°, SD = 13.5°), consistently showed a larger subpubic angle measurement than Method 1 (M = 77.3°, SD = 12.3°) (consistent bias). More than 95% of the differences (82/85) between Checkpoint and MeshLab fell within the 95% limits of agreement (− 1.4° and 11.4°).ConclusionCheckpoint and MeshLab displayed significantly different subpubic angle measurement on a 3D pelvic model, but within the 95% limits of agreement. The MeshLab tended to give a larger measurement (5°), across the magnitude of the subpubic angle. The decision to use the two methods interchangeably depended on the clinical judgment of the observer.

The angle adjustment method of the cleaning end effector for the surface of rocket tank based on machine vision

According to the actual engineering needs, the angle adjustment method of cleaning end effector for the surface of rocket tank was studied. In this paper, the PID control model was established to adjust the angle. Through the image processing algorithm, the angle between the robot cleaning end plane and the rocket tank surface was measured. Taking the angle as the controlt arget, the angle θ measured by the visual real-time is used as the feedback information, and the PI algorithm is used as the angle adjustment method. The experimental platform for angle measurement is built. After experimental verification, the method of angle measurement based on machine vision can meet the actual demand and the angle adjustment method is feasible, which is of great significance for realizing the cleaning automation of rocket tanks. This method can greatly improve the cleaning efficiency for the rocket tank surface.

The Preparation and Properties of Multilayer Cu-MTa2O5 Composite Coatings on Ti6Al4V for Biomedical Applications.

For the enhancement of the anticorrosion and antibacterial performance of the biomedical alloy Ti6Al4V, a novel Cu incorporated multilayer Ta2O5ceramic composite coating Cu-Ta2O5/Ta2O5/Ta2O5-TiO2/TiO2/Ti (coating codeCu-MTa2O5) was developed by radio frequency (RF) and direct current (DC) reactive magnetron sputtering. Meanwhile, to better display the multilayer Ta2O5 coating mentioned above, a monolayer Ta2O5 ceramic coating was deposited onto the surface of Ti6Al4V alloy as a reference. The surface morphology, microstructure, phase constituents, and elemental states of the coating were evaluated by atomic force microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. The adhesion strength, wettability, anticorrosion and antibacterial properties of the coating were examined by a scratch tester, contact angle measurement, electrochemical workstations, and plate counting method, respectively. The results showed that the deposited coatings were amorphous and hydrophobic. Cu doped into the Ta2O5 coating existed as CuO and Cu2O. A Ta2O5-TiO2/TiO2/Ti multi-interlayer massively enhanced the adhesion strength of the coating, which was 2.9 times stronger than that of the monolayer Ta2O5coating. The multilayer Cu-MTa2O5 coating revealed a higher corrosion potential and smaller corrosion current density as compared to the uncoated Ti6Al4V, indicating the better anticorrosion performance of Ti6Al4V. Moreover, a 99.8% antibacterial effect of Cu-MTa2O5 coated against Staphylococcus aureuswas obtained.

Research on dynamic angle measurement method based on electro-optical servo platform

Aiming at the measurement problem of high cost and low precision in dynamic angle, an electro-optical measurement method based on non-cooperative target vision tracking is presented. By using electro-optical servo platform mounted on the measured object to carry the camera and the laser rangefinder for the real time tracking and distance measurement of the non-cooperative target, the dynamic angle value is calculated according to the conversion relationship between the high precision angle of measurement of the servo system and the distance of the non-cooperative target. A dynamic angle measuring device is developed, and its precision calibration and error analysis are carried out. Using the high precision manual displacement table to simulate the measured dynamic angle to experiment, the feasibility of the measuring method is verified. The experimental results show that the measured angle error is 0.09° within the range of 11.082 m.

Dynamic balancing of two-plane rotor without phase angle measurement using amplitude subtraction method

Two-plane balancing is required for a rotor whose length is greater than its diameter. Balancing such a rotor is tricky, since the effects of unbalanced forces on both the planes need to be considered in determining the corrective action. This article presents a method of dynamic balancing of a two-plane rotor without the need to measure the phase angle. The rotor is balanced by measuring vibration amplitudes at the support bearing of the rotor shaft. A new rotor balancing method of amplitude subtraction is used to calculate the balancing weights and their positions on the rotor. The advantages of this method over the phase angle measurement method are also discussed in the article.

Electrospun Nanofibers: Preparation, Characterization and Atmospheric Fog Capturing Capabilities

This study was aimed at enhancing the capability of electrospun nanofiber mats to convert atmospheric fog into fresh water effectively. The demand for clean water has been increasing worldwide, and this problem can be addressed economically by utilizing new technologies. It is known that atmospheric fresh water found on the earth is about 0.03 % of the total global fresh water, which is more than enough to meet the demand for fresh water in many locations. Although desalination may produce a significant quantity of fresh water, it is a fairly costly, energy-intensive, and time-consuming process. In this research, the electrospinning method was used to fabricate superhydrophilic polyacrylonitrile (PAN) and polyvinyl chloride (PVC) nanofiber mats incorporated with hydrophilic polymers of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and chitosan at various direct current (DC) voltages, pump speeds, and tip-to-collector distances, in order to evaluate their capability of capturing fresh water from atmospheric fog. Fourier transform infrared (FTIR) and Raman spectroscopy were used to characterize the chemical structures of the nanofibers, while scanning electron microscopy (SEM) and water contact angle measurement methods were used to determine the morphology and surface hydrophobicity, respectively, of the produced nanofibers. At higher concentrations of PVP, PEG, and chitosan (e.g., 16 and 32 wt%), most of the electrospun nanofibers were superhydrophilic, with water contact angle values less than 5° in 0.5 seconds. Humidifier and humidity test chamber results indicated that superhydrophilic nanofibers could absorb up to 69 % of their weight in a shorter period of time. This scalable process can be extended to capturing a larger quantity of fresh water from the atmosphere.

Modeling and inverse control of a compliant single-tendon-sheath artificial tendon actuator with bending angle compensation

Artificial tendon is a kind of bionic actuation system capable of imitating the transmission characteristics of skeleton tendon. This paper presents a new compliant single-tendon-sheath artificial tendon actuator inspired by Hill-type muscle model. The proposed artificial tendon can perform variable compliance properties with two linear springs applying onto the tendon-sheath element. Detailed development and modeling of the actuation system is given, and transmission characteristics are analyzed and validated via simulations and experiments. Then, a bending angle measurement method is developed to compensate the variation of tendon-sheath configuration during transmission process. A model-based inverse control strategy with bending angle compensation is developed for displacement and force control without distal feedback. Trajectory tracking experiments are conducted to verify the effectiveness of the proposed control strategy. Experimental results indicate that the control errors of displacement and force control without distal feedback could be limited within 7.07% and 13.62%, respectively.

Convolutional network-based method for wall-climbing robot direction angle measurement

PurposeIn the past several decades, considerable research has been dedicated to the development of mobile systems that can traverse vertical surfaces. For the control of the climbing robot, high-precision sensing of the climbing robot’s heading angle during movement is very important. This paper aims to propose a vision-based scheme for the 2D direction angle detection of wall-climbing robots.Design/methodology/approachFirst, the authors proposed a method based on image geometric transformation to transform a camera image into a front view image of the wall, as the position and direction angle of the robot can be detected from the transformed image to eliminate the need for calibration of the camera’s internal and external parameters. Second, the AngleNet model is proposed to detect the 2D direction angle of the wall-climbing robot. Third, a training sample expansion strategy is proposed, which greatly decreased the workload of annotating training samples for AngleNet.FindingsThe single image processing time of AngleNet on the GPU is only 1.7 ms, which satisfies the demands of real-time processing. The mean and maximum error of predicted direction angle on the 556 samples of the test set are 1.1° and 3.8°, respectively.Originality/valueThis research offers an effective method for measuring the climbing robot’s direction angle in a complex outdoor environment. Combined with position detection, it can provide high-precision position and direction angle measurement information for the motion control of the climbing robot.

On-Line Measurement of Dynamic Tilt Angle by Compensating Gyroscope Drift Error

In real-time movement controlling systems, it is essential to deploy a suitable sensor to measure tilt angle on-line. When the tilt angle is bigger than the preset threshold, the remedial operation should be made timely. This paper proposes an on-line dynamic tilt angle measurement method by compensating gyroscope drift error. First, gyroscope is selected as a measuring unit because it can overcome the interference of external forces to measure dynamic angular speed. Second, an improved least squares support vector machine (LSSVM) is proposed for gyroscope drift-error compensation. The vector base learning method is used to reduce those less important support vectors, and the sparsity of LSSVM can be changed by adjusting the value of $\theta $ . Third, the quantum-behaved particle swarm optimization algorithm is introduced as the optimization method to optimize regularization parameter C and kernel parameter $\gamma $ of LSSVM model because it has good optimization result and fast convergence speed. Fourth, the experiment platform and implementation process are illustrated in detail. Finally, the corresponding experimental results demonstrate that the proposed methodology could measure the dynamic tilt angle accurately.

Evaluation of a computer-aided method for measuring the Cobb angle on chest X-rays

ObjectivesTo automatically measure the Cobb angle and diagnose scoliosis on chest X-rays, a computer-aided method was proposed and the reliability and accuracy were evaluated.MethodsTwo Mask R-CNN models as the core of a computer-aided method were used to separately detect and segment the spine and all vertebral bodies on chest X-rays, and the Cobb angle of the spinal curve was measured from the output of the Mask R-CNN models. To evaluate the reliability and accuracy of the computer-aided method, the Cobb angles on 248 chest X-rays from lung cancer screening were measured automatically using a computer-aided method, and two experienced radiologists used a manual method to separately measure Cobb angles on the aforementioned chest X-rays.ResultsFor manual measurement of the Cobb angle on chest X-rays, the intraclass correlation coefficients (ICC) of intra- and inter-observer reliability analysis was 0.941 and 0.887, respectively, and the mean absolute differences were < 3.5°. The ICC between the computer-aided and manual methods for Cobb angle measurement was 0.854, and the mean absolute difference was 3.32°. These results indicated that the computer-aided method had good reliability for Cobb angle measurement on chest X-rays. Using the mean value of Cobb angles in manual measurements > 10° as a reference standard for scoliosis, the computer-aided method achieved a high level of sensitivity (89.59%) and a relatively low level of specificity (70.37%) for diagnosing scoliosis on chest X-rays.ConclusionThe computer-aided method has potential for automatic Cobb angle measurement and scoliosis diagnosis on chest X-rays.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Wettability analysis method for assessing the effect of chemical pretreatment on brown coal biosolubilization by Gordonia alkanivorans S7

Coal wettability is of considerable importance for determining the efficiency of the solubilization process. In principle, hydrophobic coal structure should be modified for effective contact with microorganisms in the coal biosolubilization process. The paper considers the image analysis method for determining the contact angle of chemically pretreated coal, where the measurement surface is prepared by pressing coal powder into tablets. Due to sessile drop asymmetry resulting from the heterogeneity of the substrate, liquid-solid contact angles are evaluated along a three-phase contact line. The source of a three-dimensional drop image is a scan obtained with an infrared light beam from an optical coherence tomography device. The effect of coal pretreatment on biosolubilization by Gordonia alkanivorans S7 was investigated with the use of the method. To emphasize the relationship between coal wettability (hydrophilicity or hydrophobicity) and the possibility of coal liquefaction, Fourier Transform Infrared (FT-IR) spectroscopic analyses were performed. Data obtained from infrared spectra showed changes in coal structure and confirmed a positive influence of nitric acid on coal biosolubilization. Due to a high liquefaction degree, it is possible to implement the process of lignite biosolubilization by G. alkanivorans S7 on a larger scale. The contact angle measurement method can be successfully applied in the selection of methods for the chemical and biological conversion of coal in various technological processes.

Monopulse SAR angle measurement based on total variation and monotonic iterative algorithm

Synthetic aperture radar (SAR) monopulse angle measurement is an adequate method of target angle measurement in low signal-to-clutter and noise ratio. However, there is a contradiction between the instantaneous angle measurement and the SAR coherent accumulation. In this study, the authors use the total variation method to solve the above problem, and propose the monotone iterative method to enhance the efficiency of the total variation method, which is verified in the simulation.