scholarly journals Intensity Calibration in the Presence of a Disturbing Effect Dependent on Wavelength

1994 ◽  
Vol 161 ◽  
pp. 314-316
Author(s):  
P. Kotrč
Keyword(s):  
Photographic Plate ◽  
Light Conditions ◽  
Light Detector ◽  
Calibration Process ◽  
Image Structure ◽  
Factors Influencing ◽  
Calibration Methods ◽  
Flat Field ◽  
Astronomical Images ◽  
Ccd Detectors

Conversion of light detector signals to intensity values is one of the most important factors influencing precision of spectroscopic observations. Most of the classical light detectors used in astronomical practice are more or less nonlinear. As the photoemulsion has long been the most widespread nonlinear light detector, many improvements in the calibration methods concerned its nonlinearity. In addition to it, there are other substantial sources of inaccuracy in the calibration process of real astronomical images and spectrograms. They are mostly related to real light conditions in telescopes and spectrographs, as well as to the wavelength dependent sensitivity of light detectors. Some of these factors can be taken into account and involved in the calibration process. Similar effects are considered when a flat-field is evaluated for CCD detectors or when image structure varies over a photographic plate.

scholarly journals A Nonlinear Calibration Method Based on Sinusoidal Excitation and DFT Transformation for High-Precision Power Analyzers

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Wenjian Zhou ◽  
Sheng Yang ◽  
Li Wang ◽  
Hanmin Sheng ◽  
Yang Deng
Keyword(s):  
High Precision ◽  
Interpolation Method ◽  
Spline Interpolation ◽  
Calibration Method ◽  
Calibration Error ◽  
Initial Moment ◽  
Calibration Process ◽  
Calibration Methods ◽  
Nonlinear Calibration ◽  
Sinusoidal Excitation

For most high-precision power analyzers, the measurement accuracy may be affected due to the nonlinear relationship between the input and output signal. Therefore, calibration before measurement is important to ensure accuracy. However, the traditional calibration methods usually have complicated structures, cumbersome calibration process, and difficult selection of calibration points, which is not suitable for situations with many measurement points. To solve these issues, a nonlinear calibration method based on sinusoidal excitation and DFT transformation is proposed in this paper. By obtaining the effective value data of the current sinusoidal excitation from the calibration source, the accurate calibration process can be done, and the calibration efficiency can be improved effectively. Firstly, through Fourier transform, the phase value at the initial moment of the fundamental frequency is calculated. Then, the mapping relationship between the sampling value and the theoretical calculation value is established according to the obtained theoretical discrete expression, and a cubic spline interpolation method is used to further reduce the calibration error. Simulations and experiments show that the calibration method presented in this paper achieves high calibration accuracy, and the results are compensation value after calibration with a deviation of ± 3 × 10 − 4 .

scholarly journals On-Site Calibration Method for Line-Structured Light Sensor-Based Railway Wheel Size Measurement System

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6717
Author(s):  
Yunfeng Ran ◽  
Qixin He ◽  
Qibo Feng ◽  
Jianying Cui
Keyword(s):  
Structured Light ◽  
Field Tests ◽  
Calibration Method ◽  
Field Application ◽  
Calibration Error ◽  
Epipolar Constraint ◽  
Calibration Process ◽  
Calibration Methods ◽  
Calibration Accuracy ◽  
Calibration Time

Line-structured light has been widely used in the field of railway measurement, owing to its high capability of anti-interference, fast scanning speed and high accuracy. Traditional calibration methods of line-structured light sensors have the disadvantages of long calibration time and complicated calibration process, which is not suitable for railway field application. In this paper, a fast calibration method based on a self-developed calibration device was proposed. Compared with traditional methods, the calibration process is simplified and the calibration time is greatly shortened. This method does not need to extract light strips; thus, the influence of ambient light on the measurement is reduced. In addition, the calibration error resulting from the misalignment was corrected by epipolar constraint, and the calibration accuracy was improved. Calibration experiments in laboratory and field tests were conducted to verify the effectiveness of this method, and the results showed that the proposed method can achieve a better calibration accuracy compared to a traditional calibration method based on Zhang’s method.

Factors influencing glassiness in lettuce.

1986 ◽  
Vol 34 (1) ◽  
pp. 57-65
Author(s):  
R.H.M. Maaswinkel ◽  
G.W.H. Welles
Keyword(s):  
Salt Concentration ◽  
Soil Compaction ◽  
Specific Effect ◽  
Nitrogen Supply ◽  
Cultivar Differences ◽  
Light Conditions ◽  
Physiological Disorder ◽  
Factors Influencing ◽  
Nutrient Film Technique ◽  
Positive Effect

Glassiness, a physiological disorder occurring in greenhouses between November and February under low natural light conditions, is probably due to an imbalance between water uptake and transpiration. Eight greenhouse experiments were carried out during winter. Experiments with soil-grown plants showed that soil compaction and nitrogen supply were negatively correlated with the amount of glassiness whereas the amount of nightly outgoing radiation (from inside the greenhouse) was positively correlated with glassiness. Studies using the nutrient film technique showed that the positive effect of nitrogen was probably due to higher salt concentration rather than a specific effect of NO3-. Clear cultivar differences were observed with Dalida, Mistra and Rolinda showing less glassiness than Renate, Amanda Plus and Decisco. High soil compaction, high plant temperature, tolerant cultivars and higher total salt concentration could all be used to reduce glassiness. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals COMPARISON STUDY OF VERTICAL CYLINDER TANK DIAMETER MEASUREMENT BETWEEN STRAPPING AND OPTICAL METHOD

2020 ◽  
Vol 5 (3) ◽  
pp. 231-238
Author(s):  
Vera Firmansyah ◽  
Purwanto Nugroho ◽  
Herfin Yienda Prihensa ◽  
Azis Muslim
Keyword(s):  
Optical Method ◽  
Low Cost ◽  
Vertical Cylinder ◽  
Fuel Oil ◽  
Diameter Measurement ◽  
Calibration Process ◽  
Calibration Methods ◽  
Storage Area ◽  
Liquid Natural Gas ◽  
Tank Diameter

Vertical Cylinder Tank is used as a storage area or as a measuring tool. Liquids are used in the form of Fuel oil, Liquid Natural Gas, vegetable liquids, and other chemical liquids. The tank calibration results are in the form of a volume per height table that is used as a reference by Automatic Tank Gauging. There are two tank calibration methods, namely: the strapping method and the optical method. The process of measuring the inside or outside diameter of the tank becomes very important in the tank calibration process—the measurement of tank diameter by the strapping method using steel meters manually. At the same time, the optical method uses theodolite or total station. For tank diameters ≤ 5 m, the strapping method has smaller diameter measurement results with a difference of 0.7% compared to the optical method. In further research, a prototype can be developed that can accelerate the calibration process using the strapping method (for example, a vertical track measuring robot) or a low-cost prototype theodolite

Investigation of Factors Influencing Calibration Accuracy of Camera

2013 ◽  
Vol 712-715 ◽  
pp. 2331-2335
Author(s):  
Jian Hua Wang ◽  
Yu Ping Wu ◽  
Zhao Yang
Keyword(s):  
Camera Calibration ◽  
Control Point ◽  
Calibration Method ◽  
Manufacturing Error ◽  
Manufacturing Tolerance ◽  
Factors Influencing ◽  
Calibration Methods ◽  
Machine Vision Application ◽  
Calibration Accuracy ◽  
Vision Application

Camera calibration is the basis of vision-based 3D measurement. While many calibration methods have been proposed, the problem encountered in the practice of camera calibration is how to get accurate calibration parameters, which is seldom involved in references. This paper is focused on investigation of main factors influencing calibration accuracy, including manufacturing error of calibration rig, extracting error of control point and their combination. Based on the popular calibration method, simulation experiments are conducted at different error level, and the results show that the extracting error of control point has greater effect on calibration accuracy than manufacturing error of calibration rig. The manufacturing tolerance of calibration rig and extracting tolerance of control point is suggested to satisfy usual machine vision application.

Computational Intelligence Nonmodel-Based Calibration Approach for Internal Combustion Engines

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
He Ma ◽  
Ziyang Li ◽  
Mohammad Tayarani ◽  
Guoxiang Lu ◽  
Hongming Xu ◽  
...  
Keyword(s):  
Computational Intelligence ◽  
Internal Combustion Engines ◽  
Test Bench ◽  
Internal Combustion ◽  
Calibration Process ◽  
Engine Calibration ◽  
Engine Model ◽  
Model Based ◽  
Calibration Methods ◽  
Calibration Approach

Over the past 20 years, with the increase in the complexity of engines, and the combinatorial explosion of engine variables space, the engine calibration process has become more complex, costly, and time consuming. As a result, an efficient and economic approach is desired. For this purpose, many engine calibration methods are under development in original equipment manufacturers and universities. The state-of-the-art model-based steady-state design of experiments (DOE) technique is mature and is used widely. However, it is very difficult to further reduce the measurement time. Additionally, the increasingly high requirements of engine model accuracy and robust testing process with high data quality by high-quality testing facility also constrain the further development of model-based DOE engine calibration. This paper introduces a new computational intelligence approach to calibrate internal combustion engine without the need for an engine model. The strength Pareto evolutionary algorithm 2 (SPEA2) is applied to this automatic engine calibration process. In order to implement the approach on a V6 gasoline direct injection (GDI) engine test bench, a simulink real-time based embedded system was developed and implemented to engine electronic control unit (ECU) through rapid control prototyping (RCP) and external ECU bypass technology. Experimental validations prove that the developed engine calibration approach is capable of automatically finding the optimal engine variable set which can provide the best fuel consumption and particulate matter (PM) emissions, with good accuracy and high efficiency. The introduced engine calibration approach does not rely on either the engine model or the massive test bench experimental data. It has great potential to improve the engine calibration process for industries.

scholarly journals A laboratory-based Laue X-ray diffraction system for enhanced imaging range and surface grain mapping

2015 ◽  
Vol 48 (4) ◽  
pp. 1342-1345 ◽  
Author(s):  
William Whitley ◽  
Chris Stock ◽  
Andrew D. Huxley
Keyword(s):  
Single Crystals ◽  
Photographic Plate ◽  
Polycrystalline Sample ◽  
Limited Range ◽  
X Ray Diffraction ◽  
Large Area ◽  
X Ray ◽  
Diffraction Patterns ◽  
Processing Techniques ◽  
Ccd Detectors

Although CCD X-ray detectors can be faster to use, their large-area versions can be much more expensive than similarly sized photographic plate detectors. When indexing X-ray diffraction patterns, large-area detectors can prove very advantageous as they provide more spots, which makes fitting an orientation easier. On the other hand, when looking for single crystals in a polycrystalline sample, the speed of CCD detectors is more useful. A new setup is described here which overcomes some of the limitations of limited-range CCD detectors to make them more useful for indexing, whilst at the same time making it much quicker to find single crystals within a larger polycrystalline structure. This was done by combining a CCD detector with a six-axis goniometer, allowing the compilation of images from different angles into a wide-angled image. Automated scans along the sample were coupled with image processing techniques to produce grain maps, which can then be used to provide a strategy to extract single crystals from a polycrystal.

scholarly journals Long-focus CCD astrometry of planetary satellites

1996 ◽  
Vol 172 ◽  
pp. 373-388
Author(s):  
D. Pascu
Keyword(s):  
Photographic Plate ◽  
Tangent Plane ◽  
Satellite Observations ◽  
Recent History ◽  
Future Directions ◽  
Planetary Satellites ◽  
History Of ◽  
Ccd Detectors ◽  
The Impact

CCD detectors are rapidly replacing the photographic plate and photomultiplier in satellite observations used for orbital improvement. This includes both phenomena timings as well as tangent plane astrometry. In most cases this change has been for the better, but in some areas there has been no gain – even a loss. We will review this change in terms of the recent history of satellite observations. The impact of the CCD will be discussed in terms of its applications, and the increase in precision it affords. Finally, a few things will be said about future directions, especially about spin-off applications.

scholarly journals The Factors Influencing Seasonal Dynamics and Spatial Distribution of Stable Fly Stomoxys calcitrans (Diptera, Muscidae) within Stables

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 142 ◽  
Author(s):  
Marek Semelbauer ◽  
Barbara Mangová ◽  
Marek Barta ◽  
Milan Kozánek
Keyword(s):  
Spatial Distribution ◽  
Stable Fly ◽  
Seasonal Activity ◽  
Light Conditions ◽  
Air Humidity ◽  
Stable Flies ◽  
Factors Influencing ◽  
Relative Air Humidity ◽  
Flight Season ◽  
Positive Effect

The biology of the stable fly is fairly well known, but factors influencing the distribution of adult stable flies within stables are still inadequately investigated. The four experimental stables were located in south western Slovakia. Within each stable, five sticky traps were localized along the stable, and the flies were weekly counted during the flight season of years 2015–2017. Seasonal activity and stable fly abundance in relation to temperature, rainfall, light conditions, relative air humidity, and cows per stable were evaluated. The seasonal activity of the stable fly shows one large peak at the end of summer and a second smaller peak just before the end of the flight season. The spatial distribution of stable flies was unique for each stable. All of the environmental variables had significant and mostly positive effect on stable fly abundance. The strongest and most positive effect on stable fly counts was temperature and rainfall five weeks prior to collecting session. Within the stable, cow number, air humidity, and light conditions are the strongest candidates to influence their distribution.

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