This paper presents a method of correcting the effects caused by refraction phenomena in an optical measurement system. The correction algorithm proposed can be applied in many different photogrammetric applications affected by these effects. To validate this algorithm, a foot sole optical measurement system that uses several cameras to build a mesh of a foot sole has been used. This measurement system has six cameras that are protected by a safety glass that separates the cameras from the foot to be measured. The safety glass produces an air-glass-air interface that causes the refraction phenomena, producing deformations in the images. Due to the deformations it is impossible to obtain reliable metric information of the images captured using the measurement system. The developed correction algorithm is based on a grid layout and associated polynomials and makes it possible to correct the deformations and extract accurate metric information.
In the article a non-uniformity correction method is presented which allows to compensate for the influence of detector’s temperature drift. For this purpose, dependency between output signal value and the temperature of the detector array was investigated. Additionally the influence of the temperature on the Offset and Gain coefficients was measured. Presented method utilizes estimated dependency between output signal of detectors and their temperature. In the presented method, the shutter is used for establishing signal reference. Thermoelectric cooler is used for changing the temperature of the detector array.
In the second part of the article, the history of standardization programmes concerning the names of physiographic objects is discussed. The basis of the standardization programme currently followed by the Commission on Names of Localities and Physiographic Objects is described. The paper also presents the criteria of linguistic correctness adopted by the previous standardization commissions as well as by the present one. Issues of linguistic correctness of geographical names with dialectal properties and of names borrowed from minority languages are discussed. Attention is paid to some structural discrepancies in the approaches to the issue of correctness taken by the Commission on Names of Localities and Physiographic Objects and by local authorities.
When conducting geodetic and gravimetric measurements, there is a problem of projecting them to the reference surface. Since the gravitational field is inhomogeneous under the real conditions, the problem arises of determining the corrections to the measured values of gravitational acceleration in order to use the obtained data for the subsequent solutions of projection problems. Currently, the solution to this problem is performed using a Bouguer reduction, which requires information about the internal structure of the upper layer of the earth’s surface, topography, etc. The purpose of this study is to develop a methodological approach that would allow to determine the reduction (projection) corrections for gravitational acceleration on technogenic and geodynamic polygons without using data about the distribution of surface layer density and topography. The research process is based on the use of mathematical analysis methods and a wide range of experimental geodetic and gravimetric measurements. In the course of the performed researches, an algorithm was obtained and a practical implementation of the determination of the corrections in the measured values of gravitational acceleration on the basis of geodetic and gravimetric measurements was carried out at the certain geodynamic polygon in order to bring all corrections to one level surface.
A high pressure resonator transducer (0 to 100 MPa) devised by the author has been described. The elastic element of the converter consists of a cylinder with an offset arranged axis hole. Quartz resonators were used for the measurement of deformations of the pipe. Based upon the results of the transducer testing, a new algorithmic method for the minimizalizsation of the temperature error, that eliminates the need for a temperature gauge has been worked out.
Despite the large number of studies conducted on teachers’ oral corrective feedback, the findings of these studies have been mainly limited to cognitive orientations rooted in experimental designs and the verbal discourse of the teacher as the main object of inquiry. Considering teachers’ affective concerns regarding their corrective feedback and the shift from negative psychology to positive psychology in the field of second/foreign language teaching as well as the entirety of the teacher’s corrective repertoire, in this case study, we aimed to explore the enjoyment building capacity of a teacher’s multimodal corrective feedback in a university general English course. We video-recorded the teacher’s multimodal corrective feedback including verbal and nonverbal semiotic resources like gesture, gaze, and posture while observing the learners’ emotional experiences for eight sessions. We also conducted stimulated recall interviews with some learners and collected their written journals about the experiences of enjoyment with regard to the teacher’s multimodal corrective feedback scenarios. The teacher’s multimodal corrective feedback was analyzed through systemic functional multimodal discourse analysis (SF-MDA) and the content of the interview transcripts as well as the written journals were qualitatively analyzed. The findings indicated that the teacher’s inherent multimodality in his corrective feedback broadened the main dimensions of enjoyment by raising the learners’ attention to their errors, heightening their focus on the correct form, and increasing the salience of his corrective feedback. Further arguments regarding the findings are discussed.
Correctional staff is particularly exposed to occupational stress which in turn can have a negative impact on their job performance. This study attempted to analyse the role of personality, organizational factors, and stress coping strategies in shaping job satisfaction. 163 correctional staff members who were being trained at the Central Training Centre of Correctional Services in Kalisz, Poland, participated in the study. The following tools were used: The Bochum Inventory of Personal Work Features (BIP), the Multiphasic Inventory for Measuring Coping (COPE), and the Satisfaction with Job Scale (SSP).
Staff working directly with inmates scored the lowest in terms of job satisfaction. Social sensibility is a predictor of job satisfaction among each study subgroup and each correctional department and correctional staff as a whole. Correlates of job satisfaction among correctional officers were: Active coping with stressful situations and Seeking social support for emotional and instrumental reasons.
The aim of this paper is to compare the efficiency of various outlier correction methods for ECG signal processing in biometric applications. The main idea is to correct anomalies in various segments of ECG waveform rather than skipping a corrupted ECG heartbeat in order to achieve better statistics. Experiments were performed using a self-collected Lviv Biometric Dataset. This database contains over 1400 records for 95 unique persons. The baseline identification accuracy without any correction is around 86%. After applying the outlier correction the results were improved up to 98% for autoencoder based algorithms and up to 97.1% for sliding Euclidean window. Adding outlier correction stage in the biometric identification process results in increased processing time (up to 20%), however, it is not critical in the most use-cases.
This paper addresses the issue of obtaining maximum likelihood estimates of parameters for structural VAR models with a mixture of distributions. Hence the problem does not have a closed form solution, numerical optimization procedures need to be used. A Monte Carlo experiment is designed to compare the performance of four maximization algorithms and two estimation strategies. It is shown that the EM algorithm outperforms the general maximization algorithms such as BFGS, NEWTON and BHHH. Moreover, simplification of the problem introduced in the two steps quasi ML method does not worsen small sample properties of the estimators and therefore may be recommended in the empirical analysis.
The aim of the study is to discuss the relationship of the crude oil price, speculative activity and fundamental factors. An empirical study was conducted with a VEC model. Two cointegrating vectors were identified. The first vector represents the speculative activity. We argue that the number of short non-commercial positions increases with the crude oil stock and price, decreases with the higher number of long non-commercial positions. A positive trend of crude oil prices may be a signal for traders outside the industry to invest in the oil market, especially as access to information could be limited for them. The second vector represents the crude oil price under the fundamental approach. The results support the hypothesis that the crude oil price is dependent on futures trading. The higher is a number of commercial long positions, the greater is the pressure on crude oil price to increase.
The main topic of this study is the experimental measurement and mathematical modelling of global gas hold-up and bubble size distribution in an aerated stirred vessel using the population balance method. The air-water system consisted of a mixing tank of diameter T = 0.29 m, which was equipped with a six-bladed Rushton turbine. Calculations were performed with CFD software CFX 14.5. Turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the homogeneous MUSIG method with 24 bubble size groups. To achieve a better prediction of the turbulent quantities, simulations were performed with much finer meshes than those that have been adopted so far for bubble size distribution modelling. Several different drag coefficient correlations were implemented in the solver, and their influence on the results was studied. Turbulent drag correction to reduce the bubble slip velocity proved to be essential to achieve agreement of the simulated gas distribution with experiments. To model the disintegration of bubbles, the widely adopted breakup model by Luo & Svendsen was used. However, its applicability was questioned.
The paper presents definitions and relative measures of the system sensitivity and sensitivity of its errors. The model of a real system and model of an ideal measuring system were introduced. It allows to determine the errors of the system. The paper presents also how to use the error sensitivity analysis carried out on the models of the measuring system to the correction of the nonlinearity error of its static characteristic. The corrective function is determined as a relation between the input variable of the tested system and its chosen parameter. The use of the proposed method has been presented on the example of a phase angle modulator. The obtained results have been compared with the results of analytic calculations. The idea of a phase angle modulator is also presented.
This paper presents two methods for evaluation of the effective wavenumber of nearly-Gaussian beams in laser interferometers that can be used for determination of a so called diffraction correction in absolute gravimeters. The first method, that can be simply used in situ, is an empirical procedure based on the evaluation of the variability of g measurements against the amount of light limited by an iris diaphragm and transmitted to a photodetector. However, precision of this method depends on the beam quality similarly as in the case of the conventional method based on measurement of a beam width. The second method, that is more complex, is based on beam profiling in various distances and on calculation of the effective wavenumber using the second spatial derivative of a non-ideal beam field envelope. The measurement results achieved by both methods are presented on an example of two absolute gravimeters and the determined diffraction corrections are compared with the results obtained by measurements of beam width. Agreement of methods within about 1 mGal have been obtained with average diffraction corrections slightly exceeding +2 mGal for three FG5(X) gravimeter configurations.
References
[1]Monchalin, J.P., Kelly, M.J., Thomas, J.E., Kurnit, N.A., Szöke, A., Zernike, F., Lee, P.H., Javan, A.(1981). Accurate laser wavelength measurement with a precision two-beam scanning Michelson in-terferometer.Appl Opt., 20(5), 736–57.
[2]Sasso, C.P., Massa, E., and Mana, G. (2016). Diffraction effects in length measurements by laserinterferometry.Optics Express, 24(6), 6522–6531. DOI: 10.1364/OE.24.006522
[3]Niebauer, T.M., Sasagawa, G.S., Faller, J.E., Hilt, R., Klopping, F. (1995). A new generation of abso-lute gravimeters.Metrologia, 32, 159–180.
[4]vanWestrum, D., Niebauer, T.M. (2003). The diffraction correction for absolute gravimeters.Metrologia, 40, 258–263.
[5]Robertsson, L. (2007). On the diffraction correction in absolute gravimetry.Metrologia, 44, 35–39.