International Journal of Numerical Modelling-Electronic Networks Devices and Fields最新文献

This paper provides a compact, noncontiguous, high isolation, manifold triplexer operating from 25.8 to 49.5 GHz, a 62.95% wide fractional operating bandwidth. The triplexer is composed of three waveguide bandpass filters with Chebyshev responses. The initialization and loop optimization strategy of the triplexer are given. To eliminate undesired high-order mode transmission between common port and filters, ridged-waveguide topology, tuning screws, capacitive windows, and narrowing the wide edges of resonant cavities for the third filter are employed. The measured results and simulated ones are in good agreement. To our knowledge, this is the most broadband, high-power triplexer demonstrated to date.

This work proposes a novel mathematical model based on the Galerkin time-domain boundary element method for accurately calculating the lightning current distribution and lightning impulse response of the buried substation grounding grid, in a multi-layer horizontal layered soil model, by taking into account the soil ionization effect. To improve computational efficiency, the quasi-static complex image method and its closed form time-domain Green's function have been introduced into the model that has the ability to analytically calculate the mutual inductance coefficient between the branch currents of any two conductor segments and the mutual resistance coefficient between the leakage currents. The Galerkin time-domain boundary element method proposed in this work can simulate the transient lightning impulse response of a substation grounding grid buried in the multi-layer horizontal layered soil.

In order to solve the obvious nonlinear problem of temperature and complex structure of PCR instrument during nucleic acid amplification. In this paper, a new nucleic acid amplification device and temperature control algorithm were proposed. In the device, in order to improve the rise and fall rate and make the whole reaction device smaller and simpler, this paper uses a microfluidic chip for nucleic acid reaction. At the same time, in the warming and cooling module, the temperature is controlled by the semiconductor chilling plate, the air-cooled cooling device and the heat sink structure, which greatly improves the speed of nucleic acid amplification. In the algorithm, a hybrid algorithm is designed, using Particle Swarm Optimization (PSO) to optimize PID algorithm parameters, and then based on fuzzy theory, according to the temperature control requirements of nucleic acid amplification, fuzzy rules are analyzed and fuzzy reasoning is carried out, and then combined with PID to achieve rapid response and overshooting control of temperature control. Finally, the measurement noise is filtered by Kalman filter. Finally, COMSOL and MATLAB software are used to simulate and compare, and it is proved that the device has a certain heat dissipation effect in the process of nucleic acid amplification. This algorithm can improve the accuracy and robustness of the control system, improve the response speed, reduce the overshoot, shorten the adjustment time, and restrain the interference.

In this paper, an optimization technique based on the particle swarm optimization (PSO) algorithm is applied to the eXtreme gradient boosting (XGBoost) method for load modulated balanced amplifiers (LMBAs) modeling, taking into consideration both strong nonlinearity and memory effects. An overview of the basic principles of the proposed modeling technique is provided, as well as a detailed description of how the model is extracted. To improve the performance of the XGBoost model, the hyperparameters are optimized using the PSO algorithm. An in-house designed LMBA was used to perform experimental validation, which demonstrated that the new PSO-XGBoost model provided very efficient and extremely accurate predictions, especially in the case of strong nonlinearities. When compared to traditional Volterra models, canonical piecewise-linear based models, and standard XGBoost models, the proposed PSO-XGBoost model provides improved performance with reasonable complexity.

The main idea of this work is to present a numerical method based on Vieta-Fibonacci polynomials (VFPs) for finding approximate solutions of fractal-fractional (FF) pantograph differential equations and a system of differential equations. Although the presented scheme can be applied to any fractional integral, we focus on the Caputo, Atangana-Baleanu, and Caputo-Fabrizio integrals with due to their privileges. To carry out the method, first, we introduce FF integral operators in the Caputo, Atangana-Baleanu, and Caputo-Fabrizio senses. Then, by applying the Vieta-Fibonacci polynomials and their FF integral operators together with the collocation method, the problem becomes reduced to a system of algebraic equations that can be solved by Mathematical software. In the presented scheme, acceptable approximate solutions are achieved by employing only a few number of the basic functions. Moreover, the error analysis of the presented method is investigated. Finally, the accuracy of the presented method is examined through the numerical examples. The proposed scheme is implemented for some famous systems of FF differential equations, such as memristor, which is a fundamental circuit element so called universal charge-controlled mem-element, convective fluid motion in rotating cavity, and Lorenz chaotic system.

The uncontrollable angles (UAs) in direct torque control (DTC) algorithm is an important issue through which the effects of voltage vectors (VEs) on the magnetic flux and the torque are accurately determined. In this paper, a unique analysis of UAs is performed at different operating conditions, including parameters variations in two different strategies: Direct torque and stator flux control (DTC_SC) and (DTC_RC). Values of Those angles were accurately determined for wide speed, stator and rotor variations, and load changes. In addition, a detailed numerical comparison was performed in terms of these angles in the two strategies mentioned above for each operating condition. The comprehensive comparison showed the superiority of the DTC_RC strategy over its DTC_SC counterpart, being the maximum values of UAs in DTC_RC were 8°, 33°, and 21° versus 15°, 45°, and 38° in DTC_RC strategy for the following operations: Variable speed with variable stator resistance, variable speed with variable stator and rotor resistances, variable speed with variable load, respectively. MATLAB/Simulink results of the contributed analysis and comparisons were accomplished and validated. In addition, DS1103-based experimental tests supported and verified the theoretical analysis.

Medium-speed wind generators in the MW-range with high-temperature superconducting excitation winding are analyzed by means of non-linear 2D and 3D FEM models. Besides an inverter-based sinusoidal stator current feeding, a grid connection via a diode rectifier is analyzed by using coupled FEM and circuit simulations. The newly proposed modeling techniques are used to determine the excitation requirement for speed-variable, unity power factor operation at constant stator voltage, as required for a diode rectifier feeding of the stator winding. 2D FEM models in the H-A-formulation are developed and used for the calculation of the hysteresis loss in the superconducting field winding at stationary operation as well as for an investigation of field current variations in the HTS field winding. The major modeling challenges consist in very long settling times of voltage-fed models, several strong model non-linearities and high requirements on the spatial discretization. Approaches for overcoming these difficulties with reasonable computational efficiency are proposed.

The compact model plays a pivotal role as a critical link between device fabrication and circuit design. While conventional compact model theories and techniques are generally mature, the intricate physical mechanisms of gallium nitride (GaN) high-electron mobility transistors (HEMTs) pose challenges due to their strong non-linearity in high-power radio frequency (RF) applications. This complexity hinders achieving the required precision for applications using traditional modeling methods. Therefore, the development of physics-based compact modeling techniques becomes crucial for a deeper understanding of the intricate features of GaN HEMTs. This paper explores the advancements and the current state-of-the-art in physics-based compact models. The comprehensive review covers both intrinsic core models and real-device effects models. Core models are presented with a focus on fundamental concepts, development overviews, and applications. Additionally, the real-device effects models are introduced, encompassing advanced characterization techniques and modeling methodologies. Furthermore, the paper outlines future trends in physics-based compact modeling, providing valuable insights for individuals engaged in transistor compact modeling work.

In this article, a field-plated and recessed gate III-Nitride Nano-HEMT developed on β-Ga₂O₃ substrate is proposed and investigated for various performance characteristics over different temperatures. The 2DEG (Two Dimensional Electron Gas) dependence on temperature is critical for commercial utilization of GaN-based HEMTs (high electron mobility transistors). Here, the temperature influence on 2DEG for proposed HEMT over the range of 300–400 K has been investigated. The results demonstrate that the 2DEG density of proposed HEMT reduces as temperature increases. It has been observed that phonon scattering results in a sharp decline in the mobility of 2DEG as temperature increases, which causes the electric field to decrease. It also exhibited that the cut-off frequency decreased over the temperature changes from 300 to 400 K due to diminution in electron mobility. This research aims to contribute an extensive overview of proposed III-Nitride Nano-HEMT designed on a lattice-matched substrate of β-Ga₂O₃ to foster future research on the latest developments in this field.

This paper presents a new circuit approach to realize a capacitance multiplier circuit with positive and negative multiplication factors. Based on this approach, two new implementations of positive and negative grounded capacitance multiplier (GCM) circuits are proposed, which utilize only one current follower differential input transconductance amplifier (CFDITA), in conjunction with only one resistor and one virtually grounded capacitor. The presented GCM circuits can enhance a low capacitance value to a very high value (used in low frequency applications), up to 9202 times its original value. An important aspect of the proposed circuits involves designing a lossy parallel inductor circuit by interchanging the passive elements (RC:CR transformation) with each other. The obtained value of the capacitance and inductance can be controlled independently and electronically through the transconductance of CFDITA. The practical usability of the suggested circuits as first and second order filters is discussed. The functionality of the proposed GCM circuits is validated using CMOS CFDITA implemented with 180 nm TSMC technology parameters. Experimental verification of the proposed circuits and application examples is reinforced through the utilization of CFDITA implemented with readily available ICs AD844 and LM13700. These outcomes emphasize the dependability of the suggested circuits.