Journal of Modeling and Simulation in Electrical and Electronics Engineering
Volume:1 Issue: 4, Autumn 2021

In this study, a feasible decoupling method is used for a binary-element closely spaced dual-band antenna array. The decoupling setup is used for array antenna element isolation. Decoupling and matching at two widely separated frequencies are accomplished by using a two-layer (level) network approach. Moreover, impedance matching is built into the decoupling network. The antenna array consists of two elements and works in dual-band (4.9-5.4 GHz and 2.2-3.1 GHz). This is considering that the elements of the antenna arrays are strongly coupled. A decoupling network is taken into account between the array elements and each element port. Thus the mutual coupling between the array elements is reduced well. It should be noted that other decupling methods cannot isolate and match the impedance simultaneously in the two bands. This technique has been applied to the desired array. The proposed structure is simulated with High-Frequency Structure Simulator (HFSS) software.

This study proposes a single and dual-band tunable and convertible perfect absorber in the infrared band, consisting of a dielectric layer and a metallic bottom film. Primarily a tunable single-frequency absorber in the infrared region had been introduced. Subsequently, with the change in geometric structure, the proposed structure can be converted from infrared single-band to visible double-band frequency. The numerical simulation results indicate that the absorption spectrum of the single-band resonator is tuned from 337.4 THz to 210.2 THz, 227.3 THz, and 297.7 THz by changing effective parameters: ring width, ring height, and dielectric height. Next, by the parametric study of the proposed absorber dimensions, the absorption rate is obtained 99% more at the designed frequencies; lastly, the dual-band absorption with an average performance of 99.98% in the visible spectrum. The proposed plasmonic absorber in this research has a variety of applications, including sensing, imaging, wavelength-selective thermal emission, photodetectors, and so on.

In this paper, we propose an underlay cognitive radio network that consists of several secondary users and one successive relaying-aided primary user. Two half-duplex relays operate as full-duplex relays in the successive relaying technique. To improve spectral efficiency, the primary user utilizes the successive relaying technique. Inter relay interference and inter-user interference are challenges of the proposed network. For eliminating these interferences, the interference alignment method is utilized. Also, two power allocation algorithms are proposed to maximize the sum rate of secondary users and the energy efficiency of the network. In both power allocation algorithms, satisfying the quality of service of the primary user is considered. The closed-form solutions of these algorithms are obtained. We use the fractional programming approach to solve energy efficiency optimization in two steps.

One of the attractive candidates for improving the performance of tunnel transistors is cylindrical structures due to their impressive electrostatic control of the gate. But the on-state current of tunnel transistors is still very low compared to MOSFETs. An alternative is to use core-shell nanotubes rather than nanowires. In this article, we present a core-shell TFET nanotube based on a heterogeneous germanium/silicon structure. In our proposed structure, an N+ pocket is employed to enhance the on-state current. A possible manufacturing method is also proposed that is fully compatible with CMOS  technology. The main parameters of this transistor are 97.85 μA / μm on-state current, Ion / Ioff ratio of 8.26×108, SSavg  mV/dec 21.15, and fT of 878.95 GHz.

Prostate cancer is one of the most common cancers in men. Prostate-Specific Antigen (PSA) is an important biomarker in the diagnosis of prostate cancer. In the present paper, an Ion-Sensitive Field-Effect Transistor (ISFET) is introduced, employing microfluidic technology to detect PSA antigens efficiently. PSA antigen is our analyte in this sensor. Due to the PSA antigen's acidity and sensor sensitivity to the hydrogen ions and pH index, absorbing the hydrogen ion by the OH receptor on the sensor surface modulates the drive current and the device's threshold voltage. The electroosmotic flow is induced inside the microchannel by applying a voltage to the electrodes on the walls of the microchannel. Consequently, turbulence in the fluid flow in the channel has occurred that effectively moves the intended analytes toward the sensor surface. The biosensor performance is investigated by the simulations carried on in COMSOL. Our simulation results indicate that the proposed structure facilitates rapid detection and measurement of PSA concentration.

Fuzzy logic can be arranged concerning practical experiences and blended with conventional control techniques. Even though it is not the replacement of conventional control methods in many cases, a fuzzy control system eases the implementation and design process. It has also been put in use in other matters like traffic control. Increasing vehicles and insufficiency of passages capacity have led to widespread traffic emergence. While it is very difficult to widen existing roads, optimizing traffic like control schemas is still possible. This paper assumes a common four-directional crossroad where vehicles can move in a bidirectional way from each direction. A Sugeno fuzzy logic set of rules is presented to regulate the timing schedule of green lights for the crossroad concerning the vehicle accumulation at each line.

DC Stray currents represent serious problems for any electrified railway system. This paper describes a complete simulation model for evaluating rail potential and stray current for the Tehran multi-train DC railway system based on different earthing systems. In the present paper, a complete analysis of the results is presented. The simulation results clearly indicate that earthing system arrangements and other parameters influence stray currents and rail potential. The simulation results show the performance of three ground system types: grounded, ungrounded, and diode-grounded systems on rail potential and stray current.