A novel data processing method for sectional rail measurements to detect track irregularities in high-speed railways

2016 ◽  
Vol 232 (2) ◽  
pp. 435-444 ◽  
Author(s):  
Yangtenglong Li ◽  
Minyi Cen ◽  
Tonggang Zhang
Keyword(s):  
Measurement Errors ◽  
High Speed ◽  
Three Dimensional ◽  
Measurement Data ◽  
Data Processing Method ◽  
Novel Method ◽  
The Difference ◽  
Point Data ◽  
Sectional Measurement ◽  
Adjustment Equation

Static track inspection methods record the position and direction data through track surveys completed by trolleys that survey a track based on a track control network. The track inspection points must be measured in sections to decrease the likelihood of measurement errors. Certain track inspection points will be measured twice by adjacent stations, and different results will be obtained because of the measurement errors. To improve the regularity of the track, inspection point data from the sectional measurements must be processed, and differences in the results for the same inspection points must be eliminated. Therefore, this paper proposes a novel method referred to as the regularity for processing sectional measurement data (RPSMD) method, which overcomes the disadvantages of the currently available methods of processing inspection points via track-surveying trolleys and also improves the processing of nonoverlapping and overlapping inspection points. The adjustment criterion states that the difference value for the same adjusted overlapping points should be zero, and this criterion can be used to obtain the adjustment equation for each station. Using the adjustment equation, all station points can be corrected and the total regularity of the track points can be guaranteed. According to precisely measured ballastless tracks and their calculated three-dimensional coordinates, the RPSMD method and other available methods are verified by an experimentally designed precise mechanical device. The experimental results show that the accuracy of the nonoverlapping points adjusted by the RPSMD method is improved, and the accuracy is obviously higher than that obtained by the other available methods. Also, the accuracy of the RPSMD-adjusted overlapping points is much higher than that of the nonadjusted points.

All-Mach Number Density Based Flow Solver for OpenFOAM

2014 ◽  
Author(s):  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
High Speed ◽  
Guide Vane ◽  
Time Integration ◽  
Three Dimensional ◽  
Measurement Data ◽  
Test Cases ◽  
Ansys Fluent ◽  
Upwind Schemes ◽  
Time Stepping ◽  
Computational Performance

A density-based solver for turbomachinery application is developed based on the central-upwind schemes of Kurganov and Tadmor using the open source CFD-library OpenFOAM. Preconditioning of Weiss and Smith is utilized to extend the applicability down to the incompressibility limit. Implicit residual averaging, bulk viscosity damping and local time stepping are employed to speed up the simulations. A low-storage 4-stage Runge-Kutta scheme and dual time-stepping are used for time integration. The presented solver is compared with results from ANSYS Fluent 13.0 and measurement data. Three different test cases are conducted to analyze different flow conditions: The circular bump for low and high speed inviscid flows and computational performance assessment, the two-dimensional VKI turbine guide vane for viscous flows and the the three-dimensional DLR high speed centrifual compressor validating the performance for rotating turbo-machinery. All three test cases show a very good agreement between OpenFOAM and ANSYS Fluent.

scholarly journals Three-Dimensional Visualization of Myocardial Ischemia Based on the Standard Twelve-Lead Electrocardiogram

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Ying Ma ◽  
Yang Sheng ◽  
Tian Ruixia ◽  
Chen Xun
Keyword(s):  
Myocardial Ischemia ◽  
3D Visualization ◽  
Detection Threshold ◽  
Three Dimensional ◽  
Medical Knowledge ◽  
Color Pattern ◽  
Novel Method ◽  
The Difference ◽  
Pseudo Color ◽  
Electrocardiogram Ecg

A novel method was proposed for transforming the ischemic information in the 12-lead electrocardiogram (ECG) into the pseudo-color pattern displayed on a 3D heart model based on the projection of a ST injury vector in this study. The projection of the ST injury vector at a point on the heart surface was used for identifying the presence of myocardial ischemia by the difference between the projection value and the detection threshold. Supposing that myocardial ischemia was uniform and continuous, the location and range of myocardial ischemia could be accurately calculated and visually displayed in a color-encoding way. The diagnoses of the same patient were highly consistent (kappa coefficientk=0.9030) between the proposed method used by ordinary people lacking medical knowledge and the standard 12-lead ECG used by experienced cardiologists. In addition, the diagnostic accuracy of the proposed method was further confirmed by the coronary angiography. The results of this study provide a new way to promote the development of the 3D visualization of the standard 12-lead ECG, which has a great help for inexperienced doctors or ordinary family members in their diagnosis of patients with myocardial ischemia.

scholarly journals Application of microtomography and image analysis to the quantification of fragmentation in ceramics after impact loading

2017 ◽  
Vol 375 (2085) ◽  
pp. 20160166 ◽  
Author(s):  
Pascal Forquin ◽  
Edward Ando
Keyword(s):  
Silicon Carbide ◽  
High Speed ◽  
High Strain ◽  
Experimental Testing ◽  
Damage Model ◽  
Three Dimensional ◽  
The Difference ◽  
Carbide Ceramics ◽  
Fragmentation Patterns ◽  
Silicon Carbide Ceramics

Silicon carbide ceramics are widely used in personal body armour and protective solutions. However, during impact, an intense fragmentation develops in the ceramic tile due to high-strain-rate tensile loadings. In this work, microtomography equipment was used to analyse the fragmentation patterns of two silicon carbide grades subjected to edge-on impact (EOI) tests. The EOI experiments were conducted in two configurations. The so-called open configuration relies on the use of an ultra-high-speed camera to visualize the fragmentation process with an interframe time set to 1 µs. The so-called sarcophagus configuration consists in confining the target in a metallic casing to avoid any dispersion of fragments. The target is infiltrated after impact so the final damage pattern is entirely scanned using X-ray tomography and a microfocus source. Thereafter, a three-dimensional (3D) segmentation algorithm was tested and applied in order to separate fragments in 3D allowing a particle size distribution to be obtained. Significant differences between the two specimens of different SiC grades were noted. To explain such experimental results, numerical simulations were conducted considering the Denoual–Forquin–Hild anisotropic damage model. According to the calculations, the difference of crack pattern in EOI tests is related to the population of defects within the two ceramics. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

scholarly journals Algebraic Growth and Streak Formation in Shear Flows

1990 ◽  
Vol 43 (5S) ◽  
pp. S218-S218
Author(s):  
Marten T. Landahl
Keyword(s):  
Shear Flow ◽  
Velocity Component ◽  
High Speed ◽  
Shear Flows ◽  
Three Dimensional ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Algebraic Instability ◽  
Horizontal Pressure ◽  
The Difference

By examination of the long-term behavior of an initial three-dimensional and localized disturbance in an inflection-free shear flow a detailed study of the algebraic instability mechanism of an inviscid shear flow (Landahl, 1980) is carried out. It is shown that the vertical velocity component will tend to zero at least as fast as 1/t whereas, as a result of a nonzero liftup of the fluid elements, the streamwise disturbence velocity component will tend to a limiting finite value in a convected frame of reference. For an initial disturbence having a nonzero net vertical momentum along a streamline, the streamwise dimension of the disturbed region is found to grow indefinitely at a rate set by the difference between the maximum and minimum velocities in the parallel flow. The total kinetic energy of the disturbence therefore grows linearly in time through the formation of continuously elongating high-speed or low-speed regions. In these, internal shear layers are formed that intensify through the mechanism of spanwise stretching of the mean vorticity. The effect of a small viscosity is felt primarily in the shear layers so as to make them diffuse and eventually cause the disturbence to decay on a viscous time scale. For the streaky structures near a wall the horizontal pressure gradients are found to be small, making possible a simple approximate treatment of nonlinearty. Such an analysis suggests the possibility of the appearance of a rapid outflow event (“bursting”) from the wall that may occur at a finite time inversely proportional to the amplitude of the initial disturbance. On basis of the analysis presented it is proposed that algebraic growth is the primary mechanism for the formation of streaks in laminar and turbulent shear flows.

scholarly journals Recovery of the three-dimensional wind and sonic temperature data from a physically deformed sonic anemometer

2018 ◽  
Vol 11 (11) ◽  
pp. 5981-6002 ◽  
Author(s):  
Xinhua Zhou ◽  
Qinghua Yang ◽  
Xiaojie Zhen ◽  
Yubin Li ◽  
Guanghua Hao ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Sonic Anemometer ◽  
Three Dimensional ◽  
Cost Effective ◽  
Post Processing ◽  
Time Saving ◽  
Ultrasonic Signals ◽  
The Difference ◽  
Recovery Approach ◽  
Correct Data

Abstract. A sonic anemometer reports three-dimensional (3-D) wind and sonic temperature (Ts) by measuring the time of ultrasonic signals transmitting along each of its three sonic paths, whose geometry of lengths and angles in the anemometer coordinate system was precisely determined through production calibrations and the geometry data were embedded into the sonic anemometer operating system (OS) for internal computations. If this geometry is deformed, although correctly measuring the time, the sonic anemometer continues to use its embedded geometry data for internal computations, resulting in incorrect output of 3-D wind and Ts data. However, if the geometry is remeasured (i.e., recalibrated) and to update the OS, the sonic anemometer can resume outputting correct data. In some cases, where immediate recalibration is not possible, a deformed sonic anemometer can be used because the ultrasonic signal-transmitting time is still correctly measured and the correct time can be used to recover the data through post processing. For example, in 2015, a sonic anemometer was geometrically deformed during transportation to Antarctica. Immediate deployment was critical, so the deformed sonic anemometer was used until a replacement arrived in 2016. Equations and algorithms were developed and implemented into the post-processing software to recover wind data with and without transducer-shadow correction and Ts data with crosswind correction. Post-processing used two geometric datasets, production calibration and recalibration, to recover the wind and Ts data from May 2015 to January 2016. The recovery reduced the difference of 9.60 to 8.93 ∘C between measured and calculated Ts to 0.81 to −0.45 ∘C, which is within the expected range, due to normal measurement errors. The recovered data were further processed to derive fluxes. As data reacquisition is time-consuming and expensive, this data-recovery approach is a cost-effective and time-saving option for similar cases. The equation development can be a reference for related topics.

A Fully Compressible Three Dimensional Inverse Design Method Applicable to Radial and Mixed Flow Turbomachines

1990 ◽  
Author(s):  
M. Zangeneh ◽  
W. R. Hawthrone
Keyword(s):  
High Speed ◽  
Design Method ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Inverse Design ◽  
Mixed Flow ◽  
Exact Approach ◽  
Time Marching ◽  
The Difference ◽  
Inverse Design Method

A fully three dimensional compressible inverse design method for the design of radial and mixed flow machines is described. In this method the distribution of the circumferentially averaged swirl velocity, or rV¯θ on the meridional geometry of the impeller is prescribed and the corresponding blade shape is computed iteratively. Two approaches are presented for solving the compressible flow problem. In the approximate approach, the pitchwise variation in density is neglected and as a result the algorithm is simple and efficient. In the exact approach, the velocities and density are computed throughout the three dimensional flow field by employing Fast Fourier Transform in the tangential direction. The results of the approximate and exact approach are compared for the case of a high speed (subsonic) radial-inflow turbine and it is shown that the difference between the blade shapes computed by the two methods is well within the manufacturing tolerances. The flow through the designed impeller is analysed by using three dimensional inviscid and viscous time marching programs and very good correlations between the specified and computed rV¯θ is obtained.

scholarly journals Measurement and Analysis of the Stepwise Curved Surface of Diffractive Optical Elements by a Constant Speed Confocal Probe

2019 ◽  
Vol 9 (11) ◽  
pp. 2229
Author(s):  
Linlin Zhu ◽  
Yuchu Dong ◽  
Zexiao Li ◽  
Xiaodong Zhang ◽  
Fengzhou Fang
Keyword(s):  
Surface Topography ◽  
Measurement Method ◽  
Three Dimensional ◽  
Measurement Data ◽  
Diffractive Optical Elements ◽  
Optical Elements ◽  
Data Processing Method ◽  
Ultra Precision ◽  
The Stability ◽  
Precision Motion

Diffractive optical elements (DOEs) play an important role in improving imaging quality and reducing system volume. The measurement of DOE surface topography is of great significance to the evaluation of DOE quality and the optimization of its manufacturing process. However, there are still some difficulties in measuring the large curvature and the large sag of curve-based DOEs. In this paper, considering the geometrical feature information and measurement problems of curve-based DOEs, a measurement method based on a confocal measurement principle for DOE measurement is proposed. The proposed measurement data processing method is verified by a high-precision motion axis system and the stability of an ultra-precision lathe. The results show that the proposed measurement method can reconstruct and accurately evaluate the three-dimensional surface topography of DOEs.

An Investigation of the Effect of Cascade Area Ratios on Transonic Compressor Performance

1996 ◽  
Vol 118 (4) ◽  
pp. 760-770 ◽  
Author(s):  
A. R. Wadia ◽  
W. W. Copenhaver
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Area Ratio ◽  
Peak Efficiency ◽  
Trailing Edge ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wide Range ◽  
Compressor Performance ◽  
The Difference

Transonic compressor rotor performance is highly sensitive to variations in cascade area ratios. This paper reports on the design, experimental evaluation, and three-dimensional viscous analysis of four low-aspect-ratio transonic rotors that demonstrate the effects of cascade throat area, internal contraction, and trailing edge effective camber on compressor performance. The cascade throat area study revealed that tight throat margins result in increased high-speed efficiency with lower part-speed performance. Stall line was also improved slightly over a wide range of speeds with a lower throat-to-upstream capture area ratio. Higher internal contraction, expressed as throat-to-mouth area ratio, also results in increased design point peak efficiency, but again costs performance at the lower speeds. Reducing the trailing edge effective camber, expressed as throat-to-exit area ratio, results in an improvement in peak efficiency level without significantly lowering the stall line. Among all four rotors, the best high-speed efficiency was obtained by the rotor with a tight throat margin and highest internal contraction, but its efficiency was the lowest at part speed. The best compromise between high-speed and part-speed efficiency was achieved by the rotor with a large throat and a lower trailing edge effective camber. The difference in the shock structure and the shock boundary layer interaction of the four blade was analyzed using a three-dimensional viscous code. The analytical results are used to supplement the data and provide further insight into the detailed physics of the flow field.

scholarly journals System for 3D Visualization of Flaws for Eddy Current Inspection

10.14311/818 ◽  
2006 ◽  
Vol 46 (2) ◽  
Author(s):  
A. Dočekal ◽  
M. Kreidl ◽  
R. Šmíd
Keyword(s):  
Eddy Current ◽  
3D Visualization ◽  
Three Dimensional ◽  
Single Frequency ◽  
Scanning System ◽  
Data Processing Method ◽  
Eddy Current Inspection ◽  
Novel Method ◽  
The Fourier Transform ◽  
Automated Scanning

This paper presents a novel method for 3D visualization of flaws detected during Eddy Current (EC) inspection. The EC data was acquired using an automated scanning system equipped with precise eddy current probe positioning. The method was tested on a single frequency instrument with an absolute probe. The EC inspection procedure is implemented statically by registering the operating point of the instrument at each equidistant point on a tested object.The paper describes a data processing method based on the Fourier transform enabling 3D visualization of flaws. This three-dimensional image of the result of a scan enables the position of flaws to be determined, and the size and bevel (angle to the surface) of each detected flaw to be estimated. This research investigated flaws rising from the surface of the tested object, and flaw depth was not evaluated in this work. This method of visualization is simple to implement and is currently targeted for application in EC scanning devices. 

Nano-Micro Geometric Modeling Using Microscopic Image

2012 ◽  
Vol 523-524 ◽  
pp. 345-349 ◽  
Author(s):  
Shin Usuki ◽  
Kenjiro Takai Miura
Keyword(s):  
Geometric Modeling ◽  
High Speed ◽  
Large Scale ◽  
Early Stage ◽  
Three Dimensional ◽  
Measurement Data ◽  
Stage Of Development ◽  
Three Dimensional Measurement ◽  
Micro Features ◽  
Effective Use

In recent years, there are a lot of active researches on nano-micro manufacturing and metrology, since not only industrial fields but also medical fields require higher accuracy with respect to miniaturizing size of the target. However, we cannot make an effective use of three dimensional measurement data for the nano-micro design and manufacturing due to a wide variety of instruments, resolutions, and noises. In fact, the nano-micro geometric modeling is at an early stage of development in spite of its importance for the next generation. In order to find a solution to this problem, we propose to combine the multi-resolution processing with the microscopic images for high speed and non-destructive geometric modeling as well as for the homogeneous modeling from micro features to macro ones. This research includes measurement data tiling between different instruments, high resolution optical microscopic imaging, focus judgment of three dimensional microscopic data, and large scale point crowd processing. These built models are potentially applied to in-line inspections and numerical simulations. Therefore, the nano-micro geometric modeling contribute to further developments of ultra precise manufacturing and the biotechnology.

Sign in / Sign up

Export Citation Format

Share Document