MEASUREMENT SCIENCE REVIEW            Volume 23     

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       Measurement of Physical Quantities



Turgut Özseven, Zübeyir Şükrü Özkorucu:

Optimization of Support Vector Machines for Prediction of Parkinson’s Disease


As in all fields, technological developments have started to be used in the field of medical diagnosis, and computer-aided diagnosis systems have started to assist physicians in their diagnosis. The success of computer-aided diagnosis methods depends on the method used; dataset, pre-processing, post-processing, etc. differ according to the processes. In this study, parameter optimization of support vector machines was performed with four different methods currently used in the literature to assist the physician in diagnosis. The success of each method was tested on two different Parkinson's datasets and the results were compared within themselves and with the literature. According to the results obtained, the highest accuracy rates vary depending on the dataset and optimization method. While Improved Chaotic Particle Swarm Optimization achieved high success in the first dataset, Bat Algorithm achieved higher success in the other dataset. While the successful results obtained are better than some studies in the literature, they are at a level that can compete with some studies.



Siquan Zhang:

Investigation of Flux Transfer along Ferrite Core of Probe Coil for Eddy Current Nondestructive Evaluation


A probe coil with a T-core above a layered conductor with surface hole is investigated for magnetic flux transfer along the ferrite core and enhancement of eddy currents in conductor. The cylindrical coordinate system is adopted and an artificial boundary is added to the solution domain with radius b, and the general formula for calculating the impedance of the T-core coil is derived using the truncated region eigenfunction expansion (TREE) method. For four special cases with different probe configurations, coil impedance changes due to the layered conductor and defect are calculated with Mathematica software over a frequency change ranging from 100 Hz to 20 kHz. The analytical results are in good agreement with those obtained by the finite element method and experimental measurements. The results show that under the same lift-off height and excitation frequency, the impedance change caused by the conductor or defect in the coil of long core column is greater than that of the short core column coil. It indicates that the probe coil with a long core column can transfer magnetic flux to the conductor, thereby enhancing eddy currents in the conductor.



Kiril Demerdziev, Vladimir Dimchev:

Reactive Power and Energy Instrument’s Performance in Non-Sinusoidal Conditions Regarding Different Power Theories


It is important to conduct the examination of reactive power and energy instruments in normal operating conditions, due to their place in the regulated trade of electrical energy. The challenge arises when the normal operating conditions encompass non-sinusoidal voltages and currents, for two main reasons: the fact that the term reactive power/energy is not unambiguously defined in case of harmonically polluted environment and the fact that the measurement algorithm implemented in the meter is usually not explicitly presented by the producer. Different algorithms provide the same result in case of sinusoidal signals, while in case of harmonics the instrument’s performance may vary significantly, when different power theories are adopted. In the paper, a commercially available reactive energy electricity meter is tested with harmonically distorted voltage and current signals, and an analysis of its output is performed from the perspective of the implemented measuring algorithm, which is not known a priori. The tests encompass alteration of different waveform parameters and the instrument’s output is analyzed from the perspective of several reactive power theories. The conclusion of the analysis results in the meter’s performance feature illustration in correlation with different harmonic parameters and different reference conditions.



Mehmet Eren, Ramazan Gürsel Hoşbaş:

Testing the Performance of the Video Camera to Monitor the Vertical Movements of the Structure via a Specially Designed Steel Beam Apparatus


This article focuses on a specially designed steel beam testing apparatus to determine the dynamics of the structure using data obtained from different sensor systems. The analysis of these different sensor systems is performed by processing data recorded by the Global Navigation Satellite System (GNSS), vision based measurement (video camera), and accelerometer surveys. To perform this analysis, the accelerometer and GNSS receiver are installed at the steel beam’s mid-span position. The high-contrast artificial target attached to the accelerometer is recorded by a video camera to monitor the structural dynamics. Steel beam experiments show that it is compatible with the accelerometer, which is predicted as a reference sensor in detecting motion with an amplitude of 10 mm and above in the vertical direction with GNSS and determining the structural frequency by spectral analysis. On the other hand, we concluded that the video camera can be used to determine the structural dynamics in SHM because its results were compatible with the reference data even if the amplitude was too small.



Hao Yang, Yufeng Lai, Xuanqi Liu, Houshi Jiang, Jiansheng Yang:

Equivalence Ratio Modelling of Premixed Propane Flame by Multiple Linear Regression Using Flame Color and Spatial Characteristics


Equivalence ratio (Φ) is one of the most important parameters in combustion diagnostics. In previous studies, flame color characteristics have been widely applied to model the Φ of premixed hydrocarbon flames. The flame spatial characteristics also change with the varying Φ. In this paper, a high-speed color camera was employed to capture the premixed propane flame images under different Φ conditions (Φ = 0.93 to 1.53). Then, the relationship between the spatial characteristics and the Φ variation was investigated. The area and height of propane premixed flames perform a strong sensitive response to the Φ variation. Based on the research above, the Φ measurement models were constructed using color and spatial characteristics. A comparison was made between the color characteristics (Color-Φ) model and the color-spatial characteristics (Multi-dimensional-Φ) model. Both models were applied to a set of color images of a premixed propane flame, and the result indicates that the Multi-dimensional-Φ model performs with higher accuracy.



Bing-yi Miao, Xian-cheng Wang, Jun-hua Chen, Chu-hua Jiang, Meng-yao Qu:

A Novel Non-Contact Measurement Method of Ball Screw Thread Profile Detection Based on Machine Vision


The transmission accuracy of the ball screw depends on the processing quality of the thread profile. Traditional detection method of thread profile is complicated and inefficient. When shooting the thread profile of the ball screw in the normal section, the camera axis must be tilted to the lead angle, and adjustment errors are easily introduced from both the front view and the top view. When shooting in the axial section, the spiral lines block each other, so the actual thread profile cannot be captured for detection. In order to solve the above problems, a thread profile detection method is proposed: the theoretical equation of the ball screw thread profile in the axial section is derived based on the theoretical thread profile in the normal section, and the theoretical equation of the thread profile projection curve in the axial section is solved based on helix analysis, and the differential equation between them is obtained; then, the theoretical correction value of the thread profile projection curve is obtained by Linear Search to find the boundary value; the actual thread profile in both axial section and normal section is finally obtained with the theoretical correction value, which can support accurate measurement and detection of the key parameters of the thread profile. Experiments show that the proposed method can effectively improve the accuracy of the ball screw thread profile detection.




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