Measurement Science Review

A High-Performance Method Based on Features Fusion of EEG Brain Signal and MRI-Imaging Data for Epilepsy Classification

Fatma Demirezen Yağmur, Ahmet Sertbaş — Thu, 07 Mar 2024 00:00:00 +0000

A 1-dimensional (1D) and 2-dimensional (2D) biomedical signal analysis based on the Discrete Cosine Transform (DCT) feature extraction method was performed to diagnose epilepsy disorders with high accuracy. For this purpose, Electroencephalogram (EEG) data were used for 1D signal analysis and Magnetic Resonance Imaging (MRI) data were used for 2D signal analysis. The feature vectors were obtained by applying 1D DCT together with statistical methods such as mean, variance, standard deviation, kurtosis, and skewness for EEG data and by applying 2D DCT together with the statistical method of mean for MRI data. The most useful features were selected by applying Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), Forward Selection and Backward Selection methods to the obtained feature vectors. Using EEG stand-alone features, MRI stand-alone features and EEG-MRI fused features, the classification of healthy and epileptic subjects was performed in the form of two clusters. The result of epilepsy classification in this work is 96% success of 1D EEG data by using the features selected by the PCA method, 94% success of 2D MRI data using the selected features by applying the Forward Method, 100% classification accuracy of 1D EEG and 2D MRI datasets by LDA method using the obtained fused features . The article shows that the fused features of EEG-MRI can be used very effectively for the diagnosis of epilepsy.

Measurement Approach to Evaluation of Ultra-Low-Voltage Amplifier ASICs

Thu, 07 Mar 2024 00:00:00 +0000

This article presents measurement circuitry and a test board developed for experimental evaluation of prototype chip samples of Fully Differential Difference Amplifier (FDDA). The device under test (DUT) is an ultra low-voltage, high performance integrated FDDA designed and fabricated in 130 nm CMOS technology. The measurement circuits were implemented on the test board along with the fabricated FDDA chip to evaluate its main parameters and properties. In this work, we focus on evaluation of the following parameters: the input offset voltage, the common-mode rejection ratio, and the power supply rejection ratio. The test board was developed and verified. The test board error was measured to be 38.73 mV. The offset voltage of the FDDA was −0.66 mV. The measured FDDA gain and gain bandwidth are 48 dB and 550 kHz, respectively. Besides the measurement board, a graphical user interface was developed to simplify the control of device under test during measurements.

Analysis of Coupled Vibration Characteristics of Linear-Angular and Parameter Identification

Bo Tang, Jiangen Yang, Wei Chen, Xu Ming — Thu, 07 Mar 2024 00:00:00 +0000

A steady-state sinusoidal and distortion-free excitation source is very important to the accuracy and consistency of the calibration parameters of MEMS inertial sensors. In order to solve the problem that the current MEMS inertial measurement unit(IMU) calibration device is unable to reproduce the spatial motion of linear and angular vibration coupling, the research topics on the coupling vibration characteristics and parameters identification for an electromagnetic linear-angular vibration exciter are proposed. This research paper used Ampere's Law and Lorentz Force to establish the analytical expressions of electromagnetic force and electromagnetic torque of the electromagnetic linear-angular vibration exciter. Then, the main purpose of this paper is to establish single-axis and coupled vibration electromechanical analogy models containing mechanical parameters based on the admittance-type electromechanical analogy principle, and the parameter identification model is also obtained by combining the impedance formula with the additional mass method. Finally, the validity of the coupling vibration characteristics and parameter identification model are verified by the frequency response simulation and the additional mass method, and the relative error of each parameter identification is within 5% in this paper.

Design of Calibration System for Multi-Channel Thermostatic Metal Bath

Hua Zhuo, Yan Xu, Weihu Zhou, Feng Li, Yikun Zhao — Thu, 07 Mar 2024 00:00:00 +0000

The use of the thermostatic metal bath is becoming more and more extensive and the requirements for its precision and reliability are also increasing. To meet the needs of the metal bath calibration, a 12-channel thermostatic metal bath temperature field calibration system based on a four-wire PT100 has been designed. The system design includes a front-end temperature measurement component, which consists of a four-wire PT100 and a thermostatic block, and a signal processing component, which consists of a bidirectional constant current source excitation unit, a signal conditioning unit and a high-precision acquisition unit. The STM32f407 is used as the main control chip, and the analog channel selector is used for 12-channel selection. The constant current source is used for signal excitation, the proportional method is used to measure the PT100 resistance, and an acquisition circuit with a high-precision 32-bit ADS1263 analog-to-digital converter is used to amplify, filter and convert the analog signal. After piecewise linear fitting and system calibration, the temperature measurement accuracy can reach 0.4 mK, which meets the calibration requirements of the thermostatic metal bath.

Optimization of Component Assembly in Automotive Industry

Thu, 07 Mar 2024 00:00:00 +0000

This article is devoted to the positioning of glued parts by robots in the process of manufacturing automotive headlights, with the possibility of generalization to the mutual positioning of any 3D object. The authors focused on the description of the mathematical method that leads to the optimization of the robot arm setting and ensures the closest contact of the glued parts. The contact surfaces of the two joined parts are, in the ideal case, identical in shape and their optimal alignment is considered to best align the position of the nominal points on the base part with the position of the control (measured) points on the part manipulated by the robot.

Comparison of Low-Cost GNSS Receivers for Time Transfer using Zero-Length Baseline

Marek Doršic — Thu, 07 Mar 2024 00:00:00 +0000

A comparison between low-cost single-frequency and dual-frequency Global Navigation Satellite System (GNSS) receiver timing modules is presented, focusing on their suitability for time transfer applications. The study uses a zero-length baseline measurement approach to assess their performance and highlights the advantages of dual-frequency receivers. The clock comparison residuals between these lowcost devices and a reference receiver are analyzed. In particular, it is shown that the use of averages longer than 200 s can effectively mitigate the quantization error inherent in pulse per second outputs of the timing modules. The results showcase sub-nanosecond time deviation instabilities between the reference receiver and the dual-frequency timing module. In contrast, the single-frequency module exhibits time deviations of 3.3 ns at a one-day averaging interval. This research provides insights into the selection and utilization of GNSS timing modules for time transfer applications, where such modules can serve as attractive, cost-effective alternatives for applications requiring moderate accuracy.