An experimental calibration method for digital Abbe refractometer

Calibration of powder diffraction experiments using area detectors is essential to extract high quality one-dimensional powder diffraction pattern. Precise calibration necessitates a sensible characterization of the Debye-Scherrer rings formed on the detector plane. An algorithm, designed and developed to automate this process, is described in this paper. All the parameters required for an experimental calibration are extracted using robust pattern recognition techniques. Several image preprocessing methods are employed, reducing the computational cost but retaining high signal quality. A modified version of a one-dimensional Hough transformation is used to determine the final parameters of the ellipses. After extraction, the parameters are optimized using nonlinear least squares fit. The presented algorithm is insensitive to image artefacts and was successfully applied to a large number of calibration images. The performance of the algorithm is demonstrated by the comparison of results obtained from the presented automatic calibration method and an existing manual method.

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Experimental Calibration of the Overlap Factor for the Pulsed Atmospheric Lidar by Employing a Collocated Scheimpflug Lidar

Remote Sensing ◽

10.3390/rs12071227 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1227

Author(s):

Liang Mei ◽

Teng Ma ◽

Zhen Zhang ◽

Ruonan Fei ◽

Kun Liu ◽

...

Keyword(s):

Calibration Method ◽

Mie Scattering ◽

Measurement Range ◽

Atmospheric Conditions ◽

Lidar System ◽

Experimental Calibration ◽

Near Surface ◽

System A ◽

Atmospheric Remote Sensing ◽

Overlap Factor

Lidar techniques have been widely employed for atmospheric remote sensing during past decades. However, an important drawback of the traditional atmospheric pulsed lidar technique is the large blind range, typically hundreds of meters, due to incomplete overlap between the transmitter and the receiver, etc. The large blind range prevents the successful retrieval of the near-ground aerosol profile, which is of great significance for both meteorological studies and environmental monitoring. In this work, we have demonstrated a new experimental approach to calibrate the overlap factor of the Mie-scattering pulsed lidar system by employing a collocated Scheimpflug lidar (SLidar) system. A calibration method of the overlap factor has been proposed and evaluated with lidar data measured in different ranges. The overlap factor, experimentally determined by the collocated SLidar system, has also been validated through horizontal comparison measurements. It has been found out that the median overlap factor evaluated by the proposed method agreed very well with the overlap factor obtained by the linear fitting approach with the assumption of homogeneous atmospheric conditions, and the discrepancy was generally less than 10%. Meanwhile, simultaneous measurements employing the SLidar system and the pulsed lidar system have been carried out to extend the measurement range of lidar techniques by gluing the lidar curves measured by the two systems. The profile of the aerosol extinction coefficient from the near surface at around 90 m up to 28 km can be well resolved in a slant measurement geometry during nighttime. This work has demonstrated a great potential of employing the SLidar technique for the calibration of the overlap factor and the extension of the measurement range for pulsed lidar techniques.

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On the Calibration of GNSS-Based Vehicle Speed Meters

Sensors ◽

10.3390/s20030591 ◽

2020 ◽

Vol 20 (3) ◽

pp. 591 ◽

Cited By ~ 2

Author(s):

Adolfo Martucci ◽

Giovanni Cerasuolo ◽

Orsola Petrella ◽

Marco Laracca

Keyword(s):

Calibration Method ◽

Satellite System ◽

Wide Field ◽

Vehicle Speed ◽

Experimental Calibration ◽

International Laboratory Accreditation Cooperation ◽

Technical Requirements ◽

Measurement Results ◽

On The Road ◽

Global Navigation Satellite

Thanks to their metrological characteristics (accuracy, dimensions, synchronization capability, easy interfacing, and so on), in the last few years, the GNSS (Global Navigation Satellite System) based speed instruments are often used in a wide field of application. The traceability of the measurement results achieved by the GNSS instrument should be made by means of calibration procedures in compliance with the ISO/IEC 17025 standard and ILAC (International Laboratory Accreditation Cooperation) policy on the traceability of measurement results. In this context, some calibration methodologies have been proposed in the literature or used by some calibration centers. In a speed range from 1 to 300 km/h, an analysis on the suitability of the experimental calibration method (based on a couple of photocells placed on the road at a certain distance) for the GNSS speed measurement systems is presented in this paper. An analysis of the measurement setup has allowed for the recognition of both all the uncertainty contributions and defines the variability range of their values. After the formulation of the relationships between the uncertainty contributions and the total calibration uncertainty due to the calibration method, the sensitivity analysis has been made. The analyzed measurement setup, even if considering a careful choice of both instrumentations and methodologies, is suitable for the calibration of high accuracy GNSS based instruments only considering distances between the photocells sufficiently large and for speed values lower than 200 km/h. In any case, the proposed analysis can be a useful tool to allow for the choices on the measurement setup to reach the desired trade-off between calibration costs and compliance with technical requirements and also the calibration of instrumentation different by GNSS.

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Experimental Calibration Method to Validate Flame Front Propagation Data Produced by Virtual Engine Model (VEM) Computation

Volume 4: Fatigue and Fracture, Heat Transfer, Internal Combustion Engines, Manufacturing, and Technology and Society ◽

10.1115/esda2006-95217 ◽

2006 ◽

Author(s):

M. Pontoppidan ◽

G. Bella ◽

C. Fabrizi ◽

S. Ubertini

Keyword(s):

Flame Front ◽

Research Work ◽

Front Propagation ◽

Calibration Method ◽

Experimental Calibration ◽

Engine Simulation ◽

Engine Model ◽

Simulation Techniques ◽

Propagation Function ◽

True Color

The main objective of the present paper is to describe the research work accomplished to develop a combined experimental/numerical calibration method, which has the capability to validate combustion models embedded in an advanced 3-D numerical engine simulation tool. The first part of the paper describes the background for the necessity to use 3-D numerical simulation techniques as well as the basic setup requirements for both the virtual engine model and the real engine experimental support. The paper continues with a description of the method used to derive a 3-D flame front propagation function from direct true-color combustion visualizations. Finally a validation of the suggested method is presented by comparing the obtained results with those produced by an independent thermodynamic computation approach.

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Numerical simulation methodology for mode II delamination of quasi-isotropic quasi-homogeneous composite laminates

Journal of Composite Materials ◽

10.1177/0021998317695414 ◽

2017 ◽

Vol 51 (28) ◽

pp. 3955-3968 ◽

Cited By ~ 11

Author(s):

Mahzan Johar ◽

Haris Ahmad Israr ◽

Kean Ong Low ◽

King Jye Wong

Keyword(s):

Numerical Simulation ◽

Composite Laminates ◽

Cohesive Zone Model ◽

Mesh Size ◽

Calibration Method ◽

Mode Ii ◽

Zone Model ◽

Interface Shear ◽

Experimental Calibration ◽

Delamination Behavior

This work proposed a methodology to obtain the lamina and interface properties using minimal experimental works. Studies were limited to mode II delamination behavior of three quasi-isotropic quasi-homogeneous woven glass/polyester composites. It was found that the fracture toughness of 0//0, 0//45, and 45//45 laminates calculated using experimental calibration method were 0.91 N/m, 0.94 N/m, and 0.51 N/m, respectively. In addition, fiber twisting and shear cusps were observed on the delaminated surfaces of 45°-ply. Subsequently, a methodology was proposed to obtain the lamina properties for the numerical simulation without performing any additional experiment. An approach to account for the shear nonlinearity of the composite laminate due to the existence of 0°-ply was also presented. Finally, it was proposed that for reliable numerical modeling using cohesive zone model, the following parameters were recommended: penalty stiffness = 3 × 106 MPa/mm, interface shear strength = 65 MPa, mesh size = 0.5 mm, and viscosity parameter = 1 × 10−3.

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