Improved contact angle measurement in multiphase lattice Boltzmann

Contact angle is an essential parameter to characterize substrate wettability.The measurement of contact angle in experiment and simulation is a complex and time-consuming task.In this paper,an improved method of measuring contact angle in multiphase lattice Boltzmann simulations is proposed,which can accurately obtain the real-time contact angle at a low temperature and larger density ratio.The three-phase contact point is determined by an extrapolation,and its position is not affected by the local deformation of flow field in the three-phase contact region.A series of simulations confirms that the present method has high accuracy and gird-independence.The contact angle keeps an excellent linear relationship with the chemical potential of the surface,so that it is very convenient to specify the wettability of a surface.The real-time contact angle measurement enables us to obtain the dynamic contact angle hysteresis on chemically heterogeneous surface,while the mechanical analyses can be effectively implemented at the moving contact line.

A Combined Antenna Array Deployment with High Positioning Accuracy and Low Angular Measurement Error

In this paper,an antenna array composed of circular array and orthogonal linear array is proposed by using the design of long and short baseline“orthogonal linear array”and the circular array ambiguity resolution design of multi-group baseline clustering.The effectiveness of the antenna array in this paper is verified by sufficient simulation and experiment.After the system deviation correction work,it is found that in the L/S/C/X frequency bands,the ambiguity resolution probability is high,and the phase difference system error between each channel is basically the same.The angle measurement error is less than 0.5°,and the positioning error is less than 2.5 km.Notably,as the center frequency increases,calibration consistency improves,and the calibration frequency points become applicable over a wider frequency range.At a center frequency of 11.5 GHz,the calibration frequency point bandwidth extends to 1200 MHz.This combined antenna array deployment holds significant promise for a wide range of applications in contemporary wireless communication systems.

HIPPO artificial intelligence:Correlating automated radiographic femoroacetabular measurements with patient-reported outcomes in developmental hip dysplasia

BACKGROUND Hip dysplasia(HD)is characterized by insufficient acetabular coverage of the femoral head,leading to a predisposition for osteoarthritis.While radiographic measurements such as the lateral center edge angle(LCEA)and Tönnis angle are essential in evaluating HD severity,patient-reported outcome measures(PROMs)offer insights into the subjective health impact on patients.AIM To investigate the correlations between machine-learning automated and manual radiographic measurements of HD and PROMs with the hypothesis that artificial intelligence(AI)-generated HD measurements indicating less severe dysplasia correlate with better PROMs.METHODS Retrospective study evaluating 256 hips from 130 HD patients from a hip preservation clinic database.Manual and AI-derived radiographic measurements were collected and PROMs such as the Harris hip score(HHS),international hip outcome tool(iHOT-12),short form(SF)12(SF-12),and Visual Analogue Scale of the European Quality of Life Group survey were correlated using Spearman's rank-order correlation.RESULTS The median patient age was 28.6 years(range 15.7-62.3 years)with 82.3%of patients being women and 17.7%being men.The median interpretation time for manual readers and AI ranged between 4-12 minutes per patient and 31 seconds,respectively.Manual measurements exhibited weak correlations with HHS,including LCEA(r=0.18)and Tönnis angle(r=-0.24).AI-derived metrics showed similar weak correlations,with the most significant being Caput-Collum-Diaphyseal(CCD)with iHOT-12 at r=-0.25(P=0.042)and CCD with SF-12 at r=0.25(P=0.048).Other measured correlations were not significant(P>0.05).CONCLUSION This study suggests AI can aid in HD assessment,but weak PROM correlations highlight their continued importance in predicting subjective health and outcomes,complementing AI-derived measurements in HD management.

Novel Method for Spatial Angle Measurement Based on Rotating Planar Laser Beams

Spatial angle measurement, especially the measurement of horizontal and vertical angle, is a basic method used for industrial large-scale coordinate measurement. As main equipments in use, both theodolites and laser trackers can provide very high accuracy for spatial angle measurement. However, their industrial applications are limited by low level of automation and poor parallelism. For the purpose of improving measurement efficiency, a lot of studies have been conducted and several alternative methods have been proposed. Unfortunately, all these means are either low precision or too expensive. In this paper, a novel method of spatial angle measurement based on two rotating planar laser beams is proposed and demonstrated. Photoelectric receivers placed on measured points are used to receive the rotating planner laser signals transmitted by laser transmitters. The scanning time intervals of laser planes were measured, and then measured point＇s horizontal/vertical angles can be calculated. Laser plane＇s angle parameters are utilized to establish the abstract geometric model of transmitter. Calculating formulas of receiver＇s horizontal/vertical angles have been derived. Measurement equations＇ solvability conditions and judgment method of imaginary solutions are also presented after analyzing. Proposed method for spatial angle measurement is experimentally verified through a platform consisting of one laser transmitter and one optical receiver. The transmitters used in new method are only responsible for providing rotating light plane signals carrying angle information. Receivers automatically measure scanning time of laser planes and upload data to the workstation to calculate horizontal angle and vertical angle. Simultaneous measurement of multiple receivers can be realized since there is no human intervention in measurement process .Spatial angle measurement result indicates that the repeatable accuracy of new method is better than 10＂. Proposed method can improve measurement＇s automation degree and speed while ensuring measurement accuracy.

Machine Vision Based Measurement of Dynamic Contact Angles in Microchannel Flows

When characterizing flows in miniaturized channels, the determination of the dynamic contact angle is important. By measuring the dynamic contact angle, the flow properties of the flowing liquid and the effect of material properties on the flow can be characterized. A machine vision based system to measure the contact angle of front or rear menisci of a moving liquid plug is described in this article. In this research, transparent flow channels fabricated on thermoplastic polymer and sealed with an adhesive tape are used. The transparency of the channels enables image based monitoring and measurement of flow variables, including the dynamic contact angle. It is shown that the dynamic angle can be measured from a liquid flow in a channel using the image based measurement system. An image processing algorithm has been developed in a MATLAB environment. Images are taken using a CCD camera and the channels are illuminated using a custom made ring light. Two fitting methods, a circle and two parabolas, are experimented and the results are compared in the measurement of the dynamic contact angles.

Non-contact angle measurement based on parallel multiplex laser feedback interferometry

We present a novel precise angle measurement scheme based on parallel multiplex laser feedback interferometry （PLFI）, which outputs two parallel laser beams and thus their displacement difference reflects the angle variation of the target. Due to its ultrahigh sensitivity to the feedback light, PLFI realizes the direct non-contact measurement of non- cooperative targets. Experimental results show that PLFI has an accuracy of 8＂ within a range of 1400＂. The yaw of a guide is also measured and the experimental results agree with those of the dual-frequency laser interferometer Agilent 5529A.

External-cavity birefringence feedback effects of microchip Nd:YAG laser and its application in angle measurement

External-cavity birefringence feedback effects of the microchip Nd：YAG laser are presented. When a birefringence element is placed in the external feedback cavity of the laser, two orthogonally polarized laser beams with a phase difference are output. The phase difference is twice as large as the phase retardation in the external cavity along the two orthogonal directions. The variable extra-cavity birefringence, caused by rotation of the external-cavity birefringenee element, results in tunable phase difference between the two orthogonally polarized beams. This means that the roll angle information has been translated to phase difference of two output laser beams. A theoretical analysis based on the Fabry-Perot cavity equivalent model and refractive index ellipsoid is presented, which is in good agreement with the experimental results. This phenomenon has potential applications for roll angle measurement.

Design of a titl angle measurement system based on ADXL345 sensor

The titl angle measurement system based on the ADXL345 of three-axis acceleration sensor is introduced, and the composition and working principle of the system are described. The MSP430F149 microcontroller of ultra-low power and high performance is adopted. Firstly, the voltage value which is proportional to the acceleration value is output by ADXL345 when the system is powered. Secondly, the voltage value is converted into the corresponding digital signal by AD converter of the sensor. Thirdly, the digital signal is transformed into the titl angle according to the arithmetic processing of the MSP430F149. Finally, the corresponding angle is displayed on the liquid crystal display （LCD） screen. Experimental results show that the design has high sensitivity and response speed compared with the conventional methods. It is suitable for practical engineering application because of simple structure, low cost and low power consumption.

Helical angle measurement of worm by a coordinate measuring machine and its uncertainty evaluation

The purpose of the study concerns the measurement of worm's helical angle by a coordinate measurement machine in the ambient industrial environment. The novel measurement method and sampling strategy were described firstly. This method used the coordinate measurement machine to measure both of the worm gear's left and right surfaces. The worm surface was reconstructed based on the measured data of all the sampling points. Then a middle cylinder was established to truncate the fitted worm surfaces, and the truncated spiral lines were straightened to calculate the helical angle. The measurement uncertainty of worm's helical angle was evaluated by taking the difference of calculated helical angles along the truncated spiral lines on both the left and right side surfaces of the worm. Twenty-four measurement experiments show that the maximum measurement error of the proposed method is 0.105, and the measurement error ratios are all less than 3.5%. The result means that the measurement method can realize the precision measurement of worm's helical angle and can be employed in the generally industrial application.

Design of the Rotation Angle Measurement System for the Atmospheric Dispersion Corrector (ADC)

In order to measure the rotation angle error of the worm and gear mechanisms in the atmospheric dispersion corrector( ADC),a novel measurement system based on the autocollimator is designed in this paper.Based on the position relations between the shaft and spot converged by rays of autocollimator,the rotation angle can be calculated quickly and conveniently using a brief algorithm. An optical wedge is introduced to the measurement system for suppressing the awful measuring error caused by the axial wobbly error. The measurement system can measure the shaft rotation angle at any rotation position,which is the novel usage of the two-dimensional autocollimator. Its optical layout is very simple. Only an optical wedge and two plane mirrors are needed besides the autocollimator. The measurement accuracy of the proposed method is less than±0.5 arcmin. In the measurement of two worms and gears mechanisms in ADC,the rotation angle error are±0.05° and ±0.07° respectively,which all satisfies the design demand( ±0.1°). The proposed measurement system can be also suits for some engineering fields.

STUDY ON MONOPULSE ANGLE MEASUREMENT METHOD BASED ON VIRTUAL POLARIZATION MATCHING

A monopulse angle measurement method for polarization array radar is studied in this paper.The receiving signal model is established and then a monopulse angle measurement method based on virtual polarization matching is proposed.To analyze the estimation performance,the Cramer-Rao Lower Bound(CRLB)of angle estimation is derived.Both theoretical analysis and simulation show that:firstly,the proposed method is superior to the traditional angle measurement methods based on the single polarization.Secondly,the performance of the new method is unrelated to the echo polarization.Thirdly,angle estimation of this method is asymptotically optimal.The results show that this method has great potential to be used in polarization array radar.

Reliability of a Novel Cobb Protractor for Measuring the Cobb Angle of Radiograph in Scoliosis

Objective To introduce a novel Cobb protractor and assess its reliability and rapidity for measuring Cobb angle in scoliosis patients. Methods The novel Cobb protractor had two endplate markers. A measurement was performed just to align the two markers to each endplate of the curve. The Cobb angle on the posteroanterior radiographs of 24 patients clinically diagnosed with adolescent idiopathic scoliosis was measured by three orthopedic surgeons with both standard Cobb method and the new technique, and the time of measurement was recorded. Intraclass correlation coefficients(ICCs) were calculated to assess the reliability of the new method. Results The time for a measurement with the new tool was approximately 10 seconds less than the time that used to finish a measurement with the standard method(P<0.05). The overall mean Cobb angle for the major curve of the 24 patients was 47.8°. The mean overall intraobserver and interobserver ICC was 0.971 and 0.971 for the Cobb method group, while the overall intraobserver ICC and the interobserver was 0.985 and 0.979 for the new tool group. Conclusions The novel Cobb protractor could perform quick measurement and measure almost all forms of radiographs. The Cobb protractor might be an ideal instrument to measure the Cobb angle.

Orthogonality of inductosyn angle-measuring system error and error-separating technology

Round inductosyn is widely used in inertial navigation test equipment, and its accuracy has significant effect on the general accuracy of the equipment. Four main errors of round inductosyn,i.e. the first-order long-period (360°) harmonic error, the second-order long-period harmonic error, the first-order short-period harmonic error and the second-order short-period harmonic error, are described, and the orthogonality of these four kinds of errors is studied. An error separating technology is proposed to separate these four kinds of errors, and in the process of separating the short-period harmonic errors, the arrangement in the order of decimal part of the angle pitch number can be omitted. The effectiveness of the technology proposed is proved through measuring and adjusting the angular errors.

Determination of Total Vector Error of the Phasor Measurement Unit (PMU) Using the Phase Angle Error of a Constant Amplitude Voltage Signal

This paper investigates the effect of the Phase Angle Error of a Constant Amplitude Voltage signal in determining the Total Vector Error (TVE) of the Phasor Measurement Unit (PMU) using MATLAB/Simulink. The phase angle error is measured as a function of time in microseconds at four points on the IEEE 14-bus system. When the 1 pps Global Positioning System (GPS) signal to the PMU is lost, sampling of voltage signals on the power grid is done at different rates as it is a function of time. The relationship between the PMU measured signal phase angle and the sampling rate is established by injecting a constant amplitude signal at two different points on the grid. In the simulation, 64 cycles per second is used as the reference while 24 cycles per second is used to represent the fault condition. Results show that a change in the sampling rate from 64 bps to 24 bps in the PMUs resulted in phase angle error in the voltage signals measured by the PMU at four VI Measurement points. The phase angle error measurement that was determined as a time function was used to determine the TVE. Results show that (TVE) was more than 1% in all the cases.

Coordinate unification method of high-precision composite measurement in two dimensions

Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from one or more sensors. Because of the problem that standard ball is deficient as a standard artifact in the coordinate unification of high-precision composite measurement in two dimensions （2D） , a new method is proposed in this paper which uses angle gauge blocks as standard artifacts to achieve coordinate unification between the image sensor and the tactile probe. By comparing the standard ball with the angle gauge block as a standard artifact, theoretical analysis and experimental results are given to prove that it is more precise and more convenient to use angle gauge blocks as standard artifacts to achieve coordinate unification of high-precision composite measurement in two dimensions.

Clinical Effect of Tip-Edge plus Appliance in Children with Angle Ⅱ1 Malocclusion

The effects of Tip-Edge plus appliance in the treatment of Angle Ⅱ1 malocclusion and the mechanism were investigated. Fifty-two Angle Ⅱ1 children, aged from 12.3-14.2 years, with mandibu- lar retrusion in permanent dentition were selected and treated with Tip-Edge plus appliance. Lateral cephalometric films taken before and after treatment were analyzed. The arithmetic mean and standard deviation were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change. Results showed that the average treatment time was 16 months. Normal overjet and overbite were established with retroclination of upper incisors and proclination of lower incisors. U1-NA was decreased by 15.4° （P〈0.01）. ANB and Y axial angle were decreased significantly （P〈0.05） Soft tissue measurements showed that FCA and UL-E were decreased dramatically （P〈0.05）, and LL-E was increased significantly （P〈0.05）. Remarkable soft tissue change was noted after the treatment and convex facial profile changed to the straight profile. In conclusion, Tip-Edge plus technique can quickly and efficiently correct anterior bite and lateral outlook.

Development of 3D top coal caving angle model for fully mechanized extra-thick coal seam mining

During high-intensity,fully mechanized mining of extra-thick coal seam,the top coal would cave to a certain 3D form.Based on the data collected during drilling,a 3D model of top coal caving surface space was established to determine the relationship between the location of the stope roof and the caving surface,enabling the mathematical computation of the top caving angle(φ).The drilling method was employed to measure the top caving angle on two extra-thick fully mechanized coal caving faces under the conditions of three geological structures,namely,no geological structure,igneous rock structure,and fault structure.The results show that the value of top caving angle could be accurately estimated on-site with the 9-parameter 3D top coal caving surface model built with the drilling method.This method is a novel on-site measurement that can be easily applied.Our findings reveal that the characteristics of the coal-rock in the two mining faces are different;yet their caving angles follow the ruleφ_(igneous rock structure)<φ_(no geological structure)<φ_(fault structure).Finally,through the data fitting with two indexes(the top coal uniaxial compressive strength and the top caving angle),it is found that the relationship between the two indexes satisfies an exponential decay function.

TEST METHOD FOR SINGLE INTERIOR RIGHT ANGLE IN A CORNER CUBE PRISM

A new test method for single interior right angle in a corner cube prism is presented. Some key points and parameters are analyzed and derived. The advantage of this method is concluded by comparing with some current conventional methods.

Optimization of the forearm angle for arm wrestling using multi-camera stereo digital image correlation: A preliminary study

This study analyzes the function of different muscles during arm wrestling and proposes a method to analyze the optimal forearm angle for professional arm wrestlers.We built a professional arm-wrestling platform to measure the shape and deformation of the skin at the biceps brachii of a volunteer in vivo during arm wrestling.We observed the banding phenomenon of arm skin strain during muscle contraction and developed a model to evaluate the moment provided by the biceps brachii.According to this model,the strain field of the area of interest on the skin was measured,and the forearm angles most favorable and unfavorable to the work of the biceps brachii were analyzed.This study demonstrates the considerable potential of applying DIC and its extension method to the in vivo measurement of human skin and facilitates the use of the in vivo measurement of skin deformation in various sports in the future.

AngleⅡ类错牙合畸形患者牙弓宽度的测量分析

目的:比较分析AngleⅡ类错牙合畸形患者牙弓宽度及其牙弓形态特点。方法:选择AngleⅡ1类错牙合畸形患者(平均年龄15.6岁)、AngleⅡ2类错牙合畸形患者(平均年龄15.8岁)和对照组AngleⅠ类轻度错牙合畸形患者(平均年龄16.2岁)的原始模型各40副,测量每副模型的上下尖牙、第一前磨牙、第二前磨牙、第一磨牙之间的距离,计算上、下颌对应牙弓宽度差;对各组各项牙弓宽度和牙弓宽度差进行t检验。结果:AngleⅡ1类错牙合畸形患者上颌牙弓宽度较AngleⅠ类轻度错牙合畸形患者狭窄,但差异无显著性(P>0.05),AngleⅡ1类错牙合畸形患者下颌牙弓宽度与AngleⅠ类轻度错牙合畸形患者无显著差异(P>0.05);AngleⅡ2类错牙合畸形患者上颌中、后牙弓宽度和下颌牙弓宽度较AngleⅠ类轻度错牙合畸形患者的牙弓宽度窄,差异有显著性(P<0.05);AngleⅡ1类错牙合畸形患者下颌牙弓宽度比AngleⅡ2类错牙合畸形患者下颌牙弓宽大,差异有显著性(P<0.05);AngleⅡ1类错牙合畸形患者上下颌宽度差小于AngleⅠ类轻度错牙合畸形患者,尖牙、第二前磨牙处差异有显著性(P<0.05);AngleⅡ2类错牙合畸形患者上下颌牙弓宽度差与AngleⅠ类轻度错牙合畸形患者无显著差异(P>0.05);AngleⅡ1类错牙合畸形患者上下颌牙宽度差比AngleⅡ2类错牙合畸形患者小,尖牙处宽度差差异有显著性(P<0.05)。结论:AngleⅡ1、AngleⅡ2错牙合畸形患者上颌牙弓以及AngleⅡ2错牙合畸形患者下颌牙弓宽度发育均有不足,治疗中可适当进行扩弓。