Volume 70 (2019): Issue 6 (December 2019)

We describee some possible options for implementation of the Discrete multiwavelet transform (DMWT) of an image by using filter banks. DMWT can be implemented by two channel bank of vector filters which are made by cross-connected scalar filters. The properties of DGHM, CL, BiHermite and SA4 multiwavelets are here analyzed, and compression analysis for output normalization of DMWT is performed. A procedure is design of equivalent replacing of 2 channel multifilters bank by 4 channel bank of single scalar filters. Finally, we deal with a possible reduction and combinations of subbands and suggest their use.

This paper proposes a novel local descriptor evaluated from the Finite Element Analysis for human action recognition. This local descriptor represents the distinctive human poses in the form of the stiffness matrix. This stiffness matrix gives the information of motion as well as shape change of the human body while performing an action. Initially, the human body is represented in the silhouette form. Most prominent points of the silhouette are then selected. This silhouette is discretized into several finite small triangle faces (elements) where the prominent points of the boundaries are the vertices of the triangles. The stiffness matrix of each triangle is then calculated. The feature vector representing the action video frame is constructed by combining all stiffness matrices of all possible triangles. These feature vectors are given to the Radial Basis Function-Support Vector Machine (RBF-SVM) classifier. The proposed method shows its superiority over other existing state-of-the-art methods on the challenging datasets Weizmann, KTH, Ballet, and IXMAS.

Dynamic equivalent (DE) is an important process of multi-area interconnected power systems. It allows to perform stability assessment of a specific area (area of interest) at minimum cost. This study is intended to investigate the dynamic equivalent of two relatively large power systems. The fourth-order model of synchronous generators with a simplified excitation system is used as equivalent to the group of generators in the external system. To improve the accuracy of the estimated model, the identification is carried in two stages. First, using the global search Sine Cosine Algorithm (SCA) to find a starting set values, then this set is used as starting point for the fine-tuning made through the Pattern Search (PS) algorithm. To increase the reliability of the model’s parameters, two disturbances are used to avoid the identification based on a specific event. The developed program is applied on two standard power systems, namely, the New England (NE) system and the Northeast Power Coordinating Council (NPCC) system. Simulation results confirm the ability of the optimized model to preserve the main dynamic properties of the original system with accuracy.

Series linear voltage regulators are integrated circuits commonly used to make adjustable voltage sources. When used with potentiometers, these regulators are able to give adjustable voltage at the output. Memristor is a new nonlinear circuit element which came out in the last decade. It is able to provide electronically adjustable resistance. If a memristor is fed with a voltage over the threshold and it is not under saturation, its resistance also called memristance is dependent on the integration of its current, also called memristor charge. Memristor shows promise for different types and lots of digital and analog applications. In this paper, memristor-based series voltage regulator topologies are suggested and they are examined using parameters and simulations. Some design criteria have been given for the memristor-based series voltage regulators.

A simplified sensorless speed control of permanent magnet synchronous motor (PMSM) using model reference adaptive system (MRAS) is presented. The MRAS is designed and incorporated in a complete closed loop PMSM control system fed by a three-phase inverter that utilizes a simplified hysteresis current control (HCC) to generate gating signals. Accurate rotor position, being essential in PMSM control, is estimated using MRAS rather encoders and resolvers which are explicit position sensors thereby eliminating the drawbacks of the traditional speed sensors in drive systems. The performance of this model is compared with an existing model that utilizes encoders and resolvers. Superior performance was obtained from this new model with MRAS. After initial starting transients, it is observed that the rotor speed for the model with MRAS settled to steady state at 0.10 seconds as against the model with speed sensor which attained steady state at 0.31 seconds. Torque response follows the same pattern to return to the load torque of 11Nm at steady state after starting. After speed reversal, the model with MRAS restored to steady state to track the negative speed command at 0.44 seconds. This is a superior performance compared to the model with speed sensor which settled at 0.60 seconds after speed reversal. The results have clearly shown the superiority of sensorless MRAS over traditional drive models with speed sensors. The software used for this research is MATLAB/Simulink 2017 model.

This paper presents the design of a low-power and low-noise CMOS photo-transduction circuit. We propose to use the new technique of composite transistors for noise reduction of photoreceptor in the subthreshold by exploiting the small size effects of CMOS transistors. Several power and noise optimizations, design requirements, and performance limitations relating to the CMOS photoreceptor are presented. This new structure with composite transistors ensures low noise and low power consumption. The CMOS photoreceptor, implemented in a 130 nm standard CMOS technology with a 1.2 V supply voltage, achieves a noise floor of 2μV/⎷Hz within the frequency range from 1 Hz to 10 kHz. The current consumption of the CMOS photoreceptor is 541 nA. This paper shows the need for the design of phototransduction circuit at low voltage, low noise and how these constraints are reflected in the design of CMOS vision sensor.

Previous experimental studies show that the performance of IEEE 802.11 wireless LANs can be significantly degraded when obstructing moving objects and humans are present in the service area of wireless LANs. We propose the efficient MAC protocol based on the multipolling method to mitigate the interference from obstructing objects.

In this paper, a new non-contact method for detection of impact damage in carbon fibre-reinforced polymer composites with a complementary split-ring resonator sensor is proposed. The resonance frequency is evaluated as an indicator of the presence of damage. The resonator is made on a printed circuit board, and in the experimental setup it is positioned close to the area of interest. Electromagnetic models are built, and from the resonant responses the appropriate frequency range used for the test is determined. The active sensing element in the resonator is found from the analysis of the magnetic field distribution. The parametric study performed shows that a larger frequency change occurs for a wider impacted region, which is of great use for practical applications. The proposed method is validated by the experimental results, where a frequency shift of 65 MHz was observed for a 0.36 mm deep dent.

Ferroresonance is a nonlinear phenomenon that damages the undesired, destructive system for energy transmission lines. The formation and development of this overvoltage ferroresonance phenomenon is an important research topic as a mysterious event in energy power systems. In this study, Seyit Omer-Iklar energy transmission line from Turkey’s electrical transmission networks was modelled using real parameters. Ferroresonance scenario was created on the model. The energy transmission system with the scenario is set to a simulation time of 4 seconds. The first two seconds are set to normal. By cutting off the transmission line in the 2nd sec., the system is provided with ferroresonance drift. According to the data obtained therefrom, spectrograms, instantaneous amplitude, instantaneous frequency and instantaneous phase were conducted. The analyses have made clear that the instantaneous frequency amplitude defined the system’s ferroresonance moment very well.

The paper deals with the problem to obtain robust PID controller design procedure to linear time invariant descriptor uncertain polytopic systems using descriptor system stability theory and H₂ criterion approach in the form of quadratic cost function. In the frame of Lyapunov function, H₂ quadratic cost function and Bellman-Lyapunov equation the obtained designed novel procedure guarantees the robust properties of closed-loop system with parameter dependent quadratic stability/quadratic stability. In the obtained design procedure, the designer could use controller with different structure like as P, PI, PID, PI-D. For PI-D controllers D-part feedback the designer could choose any available output/state derivative variables of real systems. The effectiveness of the obtained results is demonstrated on the randomly generated examples.