Angle Measurement Method Research Articles

An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation.

This paper proposes a new optical angle measurement method in the optical frequency domain based on second harmonic generation with a mode-locked femtosecond laser source by making use of the unique characteristic of the high peak power and wide spectral range of the femtosecond laser pulses. To get a wide measurable range of angle measurement, a theoretical calculation for several nonlinear optical crystals is performed. As a result, LiNbO3 crystal is employed in the proposed method. In the experiment, the validity of the use of a parabolic mirror is also demonstrated, where the chromatic aberration of the focusing beam caused the localization of second harmonic generation in our previous research. Moreover, an experimental demonstration is also carried out for the proposed angle measurement method. The measurable range of 10,000 arc-seconds is achieved.

Radiographic measurement of canine stifle joint angles using four different landmark methods

This study was conducted to compare angles physically set on the stifle joints of cadaveric limbs of dogs with the results by four different radiographic methods for stifle angle measurement. Thirteen pelvic limbs from various large breeds and skeletally-mature dogs were used. The stifles were fixed at four angles: 125°, 130°, 135° and 140°. Altogether 52 radiographs were done. Each stifle angle set on the cadaver limbs was radiographically measured using four sets of landmarks (the goniometric, long axis, eminence and kinematic methods). We found similarity between angles physically set on cadaver limbs and radiographically measured using the long axis method (P > 0.05). The goniometric method showed similarity in group of limbs with the stifle fixed at 140° (P > 0.05), and other measurements differed significantly (P < 0.05). Eminence and kinematic method measurements were different compared to the angle of fixation of the stifle on the cadaver (P < 0.05) but similar compared to each other (P > 0.05). The method of stifle joint angle measurement should be considered when comparing similar studies, and also in pre-operative measurements for some tibial osteotomies aimed at stabilizing the joint after cranial cruciate ligament rupture.

Numerical Analysis and Investigation on the Drawbending Springbackand Fracture

In this paper, the effect of process parameters on the drawing springbackand fracture mechanism of high strength steel in drawbending process was investigated. The fracture behaviour and fracture morphology were observed and analyzed using Scanning Electron Microscope (SEM). The process parameters studied in this paper includes drawing speed, roll radius, drawing force and roll radius. The springback angle measurement method for drawing springback was also introduced and applied. The conclusions were drawn from the results. The drawbending springback angle increases withthe increase of drawing velocity. The springbackdecreases with the increase of the round roll. The large bending angle leads to the large springback. The large tension force can decrease the springback angle. The springback increases with the increase of the drawing distance. The fracture with theplane angle of 60 indicates a shear fracture and thedominated brittleness mode, which is induced by a large radius against thickness value. The fracture vertical to straight side indicates the ductility tension fracture, which is induced by a small radius against thickness value.

Human Spinal Column Diagnostic Parameter Identification Using Geometrical Model of the Vertebral Body

Abstract A geometric model and related methods to easily define patient specific vertebral body models have been introduced in our previous studies. This paper proposes an angle measurement method that can be fully automated after the definition of the patient specific vertebral body model. A Principal Component Analysis based algorithm allowing the quick identification of the symmetry plane of the human spline is also developed and described. The clinical dataset used to analyse and validate the models and methods introduced consists of 39 patients’ lumbar section of the spinal column with 195 vertebrae. In terms of angle measurement the proposed geometric model and the measurement method is proven to be accurate enough for clinical diagnostics, the average mean value of the measurement error 0.15° and 0.75° comparing the measurements to the two reference datasets. The average standard deviation of the error was around 2.50° that is almost the same as the average standard deviation of the two reference datasets (2.34°).

Kinetics of Adhesion Staphylococcus aureus on Glass in the Presence of Sodium Lauryl Sulfate

AbstractBacterial contamination of surfaces is a natural and spontaneous process that often results in the formation of biofilms. The extracellular matrix of biofilm is mostly composed of proteins, polysaccharides, and extracellular DNA and is responsible for the strong persistent ability of biofilm in the food industry. Despite cleaning and disinfection processes, persistent bacteria cause a major problem in food processing environments. Synthetic surfactants, mainly anionic surface‐active agent, are commonly used as detergents, foaming agents, wetting agents, emulsifiers, and dispersants. Their tendency to adsorb to surfaces and interfaces and modify their surface tension, is considered among their main properties. They also have the ability to attach to bioactive macromolecules such as proteins, peptides, and DNA causing cell membrane damage. In order to estimate the adhesion kinetic and proliferation of pathogenic bacteria Staphylococcus aureus, the surface of glass was coated with anionic surfactant Sodium Lauryl Sulfate (SLS). Moreover, SLS was added in suspension with the culture medium. The physicochemical properties of the material were calculated using the contact angle measurement method and bacterial hydrophobicity using the microbial adhesion to hydrocarbons (MATH) test. The obtained results showed that the number of adhering cells increased gradually as a function of time. However, changing the surface properties of the glass and S. aureus has affected the rate of adherent cells with time as well as their organization. SLS inhibited the attachment of cells, whether it is added with the microbial suspension or at the surface of the support. Generally, the present article points to a relationship between the microbial adhesion, the surface chemistry of the solid material and the bacteria, and the suspension properties.

A New Method for Velocity Ambiguity Resolution and Angle Estimation of LFMCW Vehicle Radar

Linear frequency modulated continuous wave (LFMCW) vehicle radars usually adopts multiple input multiple output (MIMO) virtual aperture angle measurement method. Traditional methods split velocity ambiguity resolution and angle estimation in two frames for further processing, causing the reduction of radar data rate. In this paper, a new method is proposed to solve this problem. This method uses the Time division multiplexing (TDM) approach to transmit and process sawtooth signals with different slope. Only one frame signal is needed for the velocity ambiguity resolution and angle estimation by using phase compensation. Simulation and theoretical analysis show that the proposed method can reduce signal processing time and improve radar data rate, with high angle measurement accuracy obtained simultaneously.

Enhanced Washburn Method (EWM): A comparative study for the contact angle measurement of powders

Washburn Method (WM) as a typical contact angle measurement (θ) method can be used for assessment of powder wettability (especially representative particle size range for flotation separation). However, as an indirect method, WM has several limitations. This investigation is going to introduce an Enhanced Washburn Method (EWM), which fills the gap of those WM obstacles, and can be applied for the meaningful indirect θ measurement of powders. For such a purpose, the wettability of quartz powders (d80: 62 μm) was measured in the absence and in the presence of the cationic surfactant Flotigam®EDA at pH 10. EWM by using pre-conditioning of hydrophobized particles via unblock capillaries measured the θ of powders in different conditions. Statistical evaluations indicated that EWM could quite accurately measure θ of the hydrophobized powders, where there is a significant coefficient of determination (R2 above 0.96) between EWM outcomes and other examined direct θ measurement methods (the captive bubble and sessile drop methods).

Parallel beam generation method for a high-precision roll angle measurement with a long working distance.

A novel measurement system for a high-precision roll angle measurement of long working distance on the basis of two parallel beams in association with two detectors is presented. The measurement system consists of a light source part and a detecting part. The light source part uses transmission grating and a plane mirror to produce a pair of high-precision parallel beams. The nonparallelism of the dual beam caused by the installation error can be compressed to ensure the measurement system achieves high-precision measurement and long working distance. The effectiveness of the measurement system and proposed methods are demonstrated by a series of experiments. The resolution of 0.5'' and measurement accuracy of 1.1'' can be obtained by the set-up measurement system.

Angle measurement method based on speckle affected laser self-mixing interference signal

Due to the speckle effect in the laser self-mixing interference (SMI), the signal amplitude will fluctuate greatly, which will affect the measurement accuracy and range. The angle measurement method based on speckle affected SMI signal is presented. The high frequency and low frequency noises in SMI signal can be filtered out simultaneously by variable mode decomposition. The envelope of SMI signal is calculated by Hilbert transform and the envelope signal is used to normalize the speckle affected SMI signal. The angle is calculated indirectly according to displacement measurement results obtained by fringe counting method. The experimental results show that the relative error of angle is ±2% with the angle measurement range of 1°.

Effects of swelling-clay and surface roughness on the wettability of transitional shale

Wettability in unconventional reservoirs is poorly understood. However, it plays a fundamental role in fluid-rock interactions, and an understanding of wetting behavior is essential for capillary seal assessments and hydrocarbon reserve estimation and recovery in clay-rich reservoirs. In this study, the wetting behavior of transitional Shanxi-Taiyuan shale from the southern North China basin was examined via the contact angle (CA) and spontaneous imbibition (SI) measurement methods. Under water-air-shale conditions, water-wet and neutral-wet behaviors were observed, whereas neutral-wet and oil-wet behaviors were observed under water-oil-shale conditions (Young's equation was used to convert the water-air-shale system to the water-oil-shale system). When the CA method was used, the shale was shown to be hydrophobic, whereas when the SI test was used, the shale was observed to be hydrophilic. The water-air CAs are negatively correlated with the total organic content (TOC), carbonate and clay mineral contents (excluding those of illite). Furthermore, iron-containing compounds, such as pyrite and siderite, were shown to decrease the water wetness. A linear negative correlation was found between the surface roughness and the CA value. The relationship between these parameters can be used to predict the CAs at different surface roughness values for a given sample. The contradictory wetting behaviors between the results of SI and CA methods can be explained by: (i) differences between the CAs formed under water-air-shale conditions and those formed under hydrocarbon-brine-shale conditions; (ii) differences in the surface roughness, which is dependent on the texture and mineralogy of the shale sample; and (iii) clay swelling after water sorption and the formation of microfractures due to water–rock interactions.

TMJ Disc Displacement Angle Analysis in MRI: A New Proposal

Objective: To evaluate the co relation of clinical symptoms and MRI findings of TMJ in symptomatic Temporomandibular Dysfunction (TMD) patients. Material and Method: MRI TMJ scan of 25 patients were evaluated. The subjects had clinical evidence of reciprocal TMJ clicking or restricted mouth opening. This study determined the variability of temporomandibular joint (TMJ) disk position in antero-posterior aspect of the joint using magnetic resonance imaging (MRI). Disk position was evaluated on MRI by measuring the angle formed by a line through the middle of the condyle and tangential to the posterior-most aspect of the disk. Joint effusion was checked using T2 weighted image sequence. Thickness of superior and inferior head of lateral pterygoid muscle was measured. These MRI findings were then correlated statistically to clinical findings. Results: Out of 50 TMJ's (25 patients); 40% had biconcave shape (no deformity), 16% cases showed lengthened disc, 12% cases showed a flattened disc, 12% cases showed thick posterior band. Varying degrees of disc displacement was associated with disc shape deformity. Increased thickness of Inferior head of lateral Pterygoid had statistically strong association with pain. Conclusion: A strong positive co relation was seen between the clinical and MRI findings in symptomatic TMD patients. Further using this, a new Disc Displacement angle measurement method and classification of disc shape was proposed for better disc evaluation.

Angle measurement technology based on magnetization vector for narrow space applications

With the wide application of laser in the field of skin plastic surgery, micro laser galvanometer scanner has made great progress in this field with its portability. However, the measurement method used to measure the deflection angle of laser galvanometer in the narrow space of scanner with high precision remains to be studied. In this paper, an angle measurement method based on magnetic field is proposed, and the effect of the shapes of permanent magnets (PMs) on the measurement is studied by theoretical and experimental study under the condition that the maximum available space for the PMs is a 10 mm side cube. An angle measuring experimental device is set up, and the contrast experiment is carried out with different PMs which are the same as simulation. The experimental results show that cylindrical PM is more suitable than other PMs, which is consistent with the simulation results, and the maximum nonlinearity error is 0.562%. This method has the advantages of small volume, non-contact measurement, small moment of inertia, good dynamic response and no external excitation for the PMs, so it has a broad application prospect in micro laser galvanometer scanner.

A High Accuracy Positioning Method for Single Base Station in Indoor Emergency Environment

Objectives In recent years, the demand of indoor and outdoor emergency location service is growing rapidly. Affected by indoor space environment, signal types, sensor performance and other factors, the existing positioning methods of single signal source, single sensor source, integrated navigation, fusion positioning are not perfect in accuracy, stability, reliability, rapidity and other aspects. The main objective of this study is to propose a high precision wireless location method for single base station in emergency positioning environment. Methods A method of angle measurement with high precision was proposed to eliminate redundant phase caused by modulated signal and sequential sampling. Firstly, a circular antenna array was constructed which sampling received signal on one channel by switching the dual polarized antenna array element in turn, and on the second channel by comparison antenna. Then, the echo signal mathematical model of dual channel antenna was established. Finally, the super-resolution angle estimation algorithm of Capon spectral and polarization decoupling was given for multipath indoor environment. In order to reduce the computational complexity of four-dimensional search, the steering vector was rewritten by hardard product, and target angle estimation was obtained by solving the minimum eigenvalue to minimize the cost function. Results From the comparison results of array phases between single channel and dual channel, it can be seen that the proposed two channel antenna has better phase stability. Experimental results on several fixed location points demonstrate that the root mean square(RMS) positioning error in X direction and Z direction is better than 0.5 m. Both static and dynamic tests show that the influence of source signal phase and frequency synchronization error to switch-antenna array can be effectively eliminated. Conclusions The proposed method can achieve two-dimensional accurate localization with a single base station, which has wider application than the single channel switch-antenna array and is easy to rapid deployment in emergency positioning environment.

A High Precision Rotating Line Detection Method for the Rotation Angle Measurement Based on Machine Vision

The accuracy of the rotation angle measurement method based on machine vision with the line as the reference target is limited by line detection accuracy. The Line Segment Detector (LSD) method is a high precision and effective method, but there are detected false lines and discontinuous lines when the LSD method is actually used to detect the rotating lines in the images. In this paper, we adjust three parts of the LSD method: image scaling, gradient magnitude threshold, and aligned points density threshold to detect lines accurately. The high precision detection of the rotating line is obtained by our adjusted method. Besides, the rotation angle measurement accuracy with the lines detected by our adjusted LSD reaches the measurement error level of arcseconds, which proves its effective performance.

Validity and Reliability of Electronic Head Posture Instrument for Measurement of Cranio-Horizontal Angle, Craniovertebral Angle and Sagittal Shoulder Angle

Background: Forward head posture (FHP) means that the head is in an anterior position in relation to the postural line and it is considered to coexist with hyperextension of upper cervical spine, flattening of lower cervical spine, rounding of the upper back and elevation and protraction of the shoulders. Because of associated problems, assessment of head posture has become increasingly important in clinical practices in evaluating and designing treatment regimens. For clinical diagnosis, angle measurements have been utilized as information for evaluating physical characteristics, determining the effects of rehabilitation and preventing injury induced by physical activity. There are various software’s available for measuring angles, one of them being Surgimap. In recent years, angle measurements using Electronic head posture instrument (EHPI) have been clinically researched as new angle measurement methods for the forward head posture apart from photographic measurement methods. Thus, this study evaluated the validity and reliability of the EHPI in measuring Head posture angles with Surgimap photograhic method in young healthy subjects. Methodology: Ethical approval for the study was granted and cross sectional observational study was conducted for validity and reliability at outpatient department. After written consent the subjects were made to understand the purpose of the study. Craniovertebral angle, Cranio-horizontal angle and Sagittal shoulder angle was measured using Electronic Head Posture Instrument and Photographic Method through Surgimap software. The research constituted of three researchers and intra rater reliability, inter rater reliability and validity was analyzed. Results: Data analysis was done using SPSS 20.0 version and the statistical significance level was set at p<0.05. Intra rater reliability was found to be CHA=0. 95, CVA=0.92 and SSA=0.96, Inter rater reliability was found to be CHA= 0.98, CVA= 0.90 and SSA= 0.78. Correlation between different angles was found as CHA=0.95, CVA=0.79 and SSA=0.62. Conclusion: EHPI is a valid and reliable tool in clinically assessing and evaluating CHA, CVA and SSA

Multi-source fiber-optic ultrasound transmitters for angle-measurement of thin medical devices

We propose an angle-measurement method involving ultrasound imaging of a transmitter for a thin medical devices used in minimally invasive surgery. We fabricated a fiber-optic ultrasound transmitter with multiple ultrasound sources for angle-measurement. The angles can be measured by an image of multiple ultrasound sources. To form ultrasound sources not only at the tip but also in the middle of an optical fiber, gap structures are formed by connecting fibers with adhesive that contains micrometer-sized particles to scatter light. A portion of the propagating laser light is taken out at the connected point by light scattering and converted to an ultrasound pulse. We fabricated a two-source transmitter and confirmed that they have the patterns in an ultrasound image. We conducted angle-measurement with our two-source ultrasound transmitter and a one-dimensional array probe. The error of measurement was less than 2° and 10° for polar and azimuth angles, respectively.

Design and experimental study of the biorthogonal linkage laser self-mixing angle sensor

In order to make up the defects of low-resolution and narrow measurement range ubiquitous in the current angle-measurement method, a biorthogonal linkage laser self-mixing angle sensor is designed for the micro-radian angular measurement over the full-circle range by taking the Acrylonitrile–butadiene–styrene resin as the material and adopting the 3D printing technology. The experimental results are in excellent agreement with the theoretical values, of which implies that the tool is capable of measuring the angle with effectively and accurately. Furthermore, the deviation degree between the measured and actual angle, and the experimental error are further investigated and discussed. As a result, this self-mixing angle sensor can greatly improve the angle measurement accuracy and reduce the experimental error rate. In the case of different rotating angles of 250 and 500 μrad, which corresponding to the angular resolution is better than 29.53 μrad and the relative error can be smaller than 3.18×10−4 %.

Trochlear dysplasia influences patellotrochlear index when measuring patella alta

Objectives:Patella alta is a risk factor for patellar instability and its recurrence after treatment. The patellotrochlear index (PTI) is a measurement used to quantify patella alta, describing patellar engagement in the trochlea through an index of trochlear overlap with patellar articular surface based on sagittal imaging. Values less than 20% have been reported to indicate patella alta, yet this measurement has primarily been described in normal knees. Trochlear dysplasia is also a common risk factor in patellar instability and can affect the length of the trochlea. Therefore the purpose of this study was to compare PTI measurements in knees with and without trochlear dysplasia, and to describe its relationship with trochlear length.Methods:Knees with trochlear dysplasia (defined by trochlear depth<4mm) based on CT imaging were identified from a series of knees with symptomatic patellar instability and compared to age- and gender matched asymptomatic controls. Measurements of patellar height including PTI and Caton Deschamps Index (CDI) were performed, as well as additional measurements of trochlear dysplasia including lateral trochlear inclination [LTI] and sulcus angle [SA]. Trochlear length was quantified using a previously described method of trochlear center-edge angle (TCEA) measurement, an angle between the posterior femoral cortical line with its intersection with Blumensaat’s line to the most proximal margin of the trochlea, with a smaller angle indicating more proximal extension of the trochlea. TCEA was measured at the central, medial, and lateral trochlea. Measurements were compared between dysplastic and control groups using t-test. Linear and multivariate regression analyses were performed to assess the relationship between PTI and measurements of trochlear dysplasia.Results:21 knees with trochlear dysplasia (13 female and 8 male) were included in this study, and were compared with 21 age- and gender-matched controls. In the dysplastic group, trochlear depth (TD) was 0.7+/-2.4mm vs 6.8+/-2.5mm (p<0.001) in the control group, SA was 154.2+/-11.5 degrees vs 134.0+/-8.3 degrees (p<0.001), and LTI was 12.1+/-6.2 vs 23.7+/-4.4 degrees (p<0.001) . Despite CDI being greater in the symptomatic group (1.19+/-0.23 vs 1.06+/-0.19, p=0.053), PTI was greater (with more overlap) in the symptomatic group (34.92+/-15.23% vs 25.43+/-21.55%, p=0.076). In the symptomatic group, the trochlear groove extended more proximally at the central (TCEA 58.4 degrees vs 68.6 degrees, p<0.001) and medial aspects (68.9 degrees vs 77.9 degrees, p<0.001). In dysplastic knees, PTI demonstrated a weak negative correlation with TCEA (R=-0.40) and with LTI (R=-0.45).Conclusion:In this study, knees with trochlear dysplasia had a PTI of 35% vs 25% in the control group, indicating greater patellar engagement despite having greater measurements of patella alta based on CDI (1.19 vs 1.06). PTI correlated with increased proximal extension of the trochlea which may account for the greater patellofemoral overlap. As abnormal trochlear length can associated with supratrochlear spurs, greater values on PTI may not necessarily indicate functional patellofemoral engagement. Further studies are needed to identify the functional relationship between trochlear length and patella alta.

In vitro evaluation of Zeolite-nHA blended PCL/PLA nanofibers for dental tissue engineering

This study aimed to investigate the potential of a composite poly(lactic acid)/polycaprolactone (PLA/PCL) blend electrospun nanofiber containing both nano-hydroxyapatite (nHA) and zeolite for promoting the proliferation of human dental pulp-derived stem cells (hDPSCs) with possible application in dental tissue engineering. For this purpose, nHA and Zeolite were synthesized via the hydrothermal method and their morphological features and crystals properties were studied by FE-SEM and X-ray diffraction, respectively. PCL-PLA/nHA/zeolite nanofibers were fabricated via electrospinning and characterized through FT-IR and water contact angle measurement methods. Then, the viability and adhesion of hDPSCs on the fibers were investigated by MTT assay and FE-SEM, respectively. The results showed that the viability of hDPSCs on the PCL-PLA/Zeolite scaffolds was significantly improved after 1, 7 and 14 days of culturing and maximum enhancing on the cell viability was detected after 3 days on PCL-PLA/nHA scaffolds (P ≤ 0.001). After 7 and 14 days of incubation, cell growth on the scaffolds containing both nHA and Zeolite was better than the nanofibers which were loaded with nHA alone. Briefly, these results revealed that Zeolite-loaded nanofiber is the most suitable scaffold for bone and tooth tissue engineering applications. More studies are required to investigate the efficiency of zeolite-based nanofibrous scaffolds for the development of artificial scaffolds for dental tissue regeneration.

Research on the multi-longitudinal mode laser self-mixing static angle-measurement system using a right-angle prism

Abstract A static absolute angle measurement method using a right-angle prism as the angle-sensing device is developed for measuring the deflection angle by means of the multi-longitudinal mode laser self-mixing sensor. In the experiment, a laser diode operating at multiple excitation longitudinal modes is exploited as the optical source for deflection angle measurement. The measured self-mixing waveforms are in accordance with the simulated waveforms, of which demonstrate that the multi-longitudinal mode laser self-mixing sensor is available for measuring the deflection angle. Meanwhile, the angle-measurement range of the self-mixing sensing system is as many as ±6.00° corresponding to 0.20° angular resolution. Furthermore, both of the absolute angle measurement error and the linear correlation of the measured angle and the actual angle are further analyzed and investigated.