Volume 74 (2023): Edizione 2 (April 2023)

Progress in the fibre optic technology spurred the development of optical fibre-based sensors. A successful fibre optics-based element for sensorial systems is fibre Bragg grating. It allows to read the measured value by the spectral shift of light, which is the variable with a good potential for accurate measurement. Various types of the interrogation of the light spectrum reflected from the measuring grating are discussed in this article and the work concentrates on the spectrum scanning that gives the good chances to diminish measuring errors by a proper choice of parameters. The focal point is the accuracy of establishing the correct value of the maximum reflectance wavelength. The significance of the noise in the photoelectric scanning signal for the measuring accuracy is analysed and the crucial factor is found in the minimizing the reflectance spectral width of the measuring grating and using the spectrum of the scanning light with the same or smaller spectral width. An important aspect is the relation of the maximal reflectance and the wavelength width of the measuring grating reflectance spectrum. The article also shows the potentiality of the apodized gratings for improving the scanning interrogation. A specific index apodization profile was analysed and its advantages are discussed.

Surface mounted permanent magnet synchronous motors can be found in several designs regarding configuration of magnets on the rotor. Finding the most optimal design in terms of the high efficiency and power factor, small cogging torque and material consumption along with good overloading capability could be a challenging task. This paper analyzes three different rotor designs of surface permanent magnet motors regarding their magnet shapes. All three motors have the same outer dimensions, output power, torque and the material properties. The comparison of all three models is performed and advantages and drawbacks of each model are pointed out. Four design variables are selected to be varied within prescribed limits for each motor model in order the best combination of number of conductors per slot, magnet thickness, the magnet length and shape to be fond, which result with the highest efficiency, small cogging torque and good overloading capability of the motor. The impact of each varied parameter on motor efficiency and cogging torque is presented. All three optimized model are compared and the most optimal model in terms of the above-mentioned characteristics is analyzed by finite element method (FEM) and with the Simulink. The model in Simulink allows motor transient characteristics to be obtained. The performed analysis is useful for determining the most optimal and cost-effective solution among presented three types of surface mounted permanent magnet motors in terms of the high efficiency and power factor, small cogging torque and material consumption.

Sixth generation (6G)-enabled internet of things (IoT) requires significant spectrum resources to deliver spectrum availability for massive IoT’s nodes. But the existing orthogonal multiple access limits the full utilization of limited spectrum resources. The non-orthogonal multiple access (NOMA) exploits the potential of power domain to improve the connectivity for 6G-enabled IoT. An efficient quality of service (QoS) aware power allocation approach is required to enhance the spectral efficiency and energy of NOMA based 6G-enabled IoT nodes. The multi-objective genetic algorithm (MOGA) is used to resolve the non-convex problem by considering the successive interference cancellation (SIC), QoS, and transmission power. Extensive experiments are drawn by using the Monte Carlo simulation to evaluate the significant improvement of the proposed model. Experimental results indicate that the proposed power allocation model provides good performance of the NOMA based IoT network.

Accurate detection of gas/odor requires highly selective gas sensor. However, the high-performance classification of gases/odors can be achieved using partial-selective gas sensors. Since 1980s, an array of broadly tuned (partial-selective) gas sensors have been used in several fields of science and engineering, and the resulting gas sensing systems (GSS) are popularly known as electronic noses (e-Noses). The combination of similar or different sensors in the array indirectly compensates for the requirement of high selectivity in GSS. Further, e-Nose’s performance inevitably depends on the salient features drawn from the initial responses of the gas sensor array (GSA). So obtained features are referred to as the responses of virtual sensors (VS). In this paper, we have proposed the three-input and three-output (TITO) technique to derive efficient virtual sensor responses (VSRs) which outperform its well-published peer technique. A GSA consisting of four elements is used to demonstrate the proposed technique. Our proposed technique augments the VSRs by four times compared to its peer. The efficacy of our proposed technique has been tested using nine fundamental classifiers, viz., linear support vector machine (100%), decision tree (97.5%), multi-layer perceptron neural network (100%), K-nearest neighbor (85%), logistic regression (100%), Gaussian process with radial basis function (95%), linear discriminant analysis (97.5%), random forest (100%), and AdaBoost (95%). Ten-fold cross-validation has been used to minimize the biasing impact of the intra- and inter-class variance. With the result, four classifiers successfully provide an accuracy of 100 percent. Hence, we have proposed and vindicated an efficient technique.

To improve the whole characteristic of the LDO, a low quiescent current structure of high voltage LDO with self-regulation impedance buffer and bandgap amplifier is presented in this paper. With the bandgap amplifier proposed, the function of voltage reference and error amplifier can be achieved simultaneously, which can efficiently reduce the consumption. The load capacitor can be as small as 0.47µF by using the self-regulation impedance buffer and current buffer compensation scheme. The LDO has been implemented in a 0.18 µm process with die size 0.03 mm² . Without the load, the consumption quiescent current of the LDO is 1 µA. Experimental result shows that the overshoot and undershoot of line transient response are less than 30 mV/V. The load regulation is about 0.1A, and line regulation is about 0.07 mV/V at no load condition.

This paper presents the optimal design of the permanent magnet brushless DC (BLDC) motor for electromobility propulsion applications. Two BLDC machines were analyzed: (a) – exterior rotor machine, and (b) – interior rotor machines The optimization of both motors structures was executed by the Taguchi method. The device structure was described by three design variables. The functional parameter (efficiency) and the economic parameter (total mass of the permanent magnets) were included in the objective function. The BLDC motors have been modelled using a finite element method (FEM). Finally, the functional parameters for both motor constructions were compared. The selected results of the calculations were presented and discussed.

High-speed and high-frequency PCB interconnect solutions with the slightest discontinuities in the physical geometry along the microstrip transmission line can significantly degrade the integrity of the signal being transferred. This paper presents an analysis of SMT component pads and their impact on the successive transmission line impedance. During 0805, 1206 and 2512 package size SMT component pad discontinuity evaluations it was spotted, that the increasing deviation from target impedance affects the microstrip impedance segment following the discontinuity. A 25 Ω impedance offset at the SMT pad reduces the line impedance afterwards by up to 7 Ω. A 37 Ω impedance offset results in a microstrip impedance reduction by up to 15 Ω, whereas a 45 Ω impedance change leads to a reduction of successive segment impedance by up to 30 Ω. This effect is also present in multiple evenly-spaced discontinuities. But a single reference plane cut-out, which is twice as wide as the SMT component discontinuity, substantially improves the overall impedance of the transmission line, including the successive line segment impedance drop.

Nowadays, 3D eddy current nondestructive characterization of crack and corrosion defects while using ECA remains an industrial challenge because the obtained image permits to determine only the 2D defect shape. Consequently, this article is devoted to determine directly the crack length and width by eddy current images through sensor array. Afterwards, we extract the maximal impedance amplitude to estimate the crack depth while using the deterministic algorithm that we have recently developed. In fact, the obtained results have demonstrated the effectiveness and the reliability of the proposed method.

In order to clarify the distribution law of the radiation optical field of the gas insulated switchgear disconnector defect and determine the detection range of partial discharge optical sensor, the optical model of the gas insulated switchgear disconnector based on the uniform geometrical theory of diffraction theory is established based on ray tracing method, and the distribution of the radiation light field is calculated when partial discharge occurs at the key positions such as the basin insulator, shield, and support insulator barrel. Based on the maximum irradiance, average irradiance and attenuation characteristics on the shell interface, the distribution law is further analysed, and based on this, the optimal location of the ultraviolet detector is proposed.

A compact dual-mode bandpass filter with independently tunable second passband is proposed based on modified V shaped resonators. By switching the pin diodes at each end of the studied resonators, the second passband is independently tuned without affecting the first passband. A prototype of the dual-mode bandpass filter with a dual-passband of 2.54 GHz and 3.36 GHz or a single passband of 2.54 GHz is designed and verified experimentally.