IRANIAN JOURNAL OF ELECTRICAL AND ELECTRONIC ENGINEERING
Year:2024 | Volume:20 | Issue:3|Papers Count:13

In this paper, a dual-active bridge converter based on the utilization of two transformers is presented. The principles of operation, switching strategy, and transmission power characteristics of the proposed converter under normal operation are discussed, comprehensively. Moreover, the RMS current of two transformers with different values of inductances of the inductors that are in series with the transformers; is discussed. The operation of the proposed dual active bridge (DAB) converter under the open-circuit failure of transformers is studied. In addition, the loss distribution of the proposed converter in different powers is investigated. The proposed dual-transformer-based dual-active bridge converter is compared with the presented converters. Finally, the proposed converter with a low-voltage side (VL= 300 V), the switching frequency of power MOSFETs (fs= 50 kHz), and an accurate model of the electric battery at a high-voltage side (VH= 450 V) are simulated to verify the way of charging and discharging the electrical battery with the proposed converter under normal and open-circuit fault of transformers.

In this paper, an innovative vertical bi-channel tunnel field effect transistor is presented that exploits line tunneling mechanism to achieve improved electrical performance. In this device, the source contains germanium, while the channel and drain regions consist of GaAs., which results in a type-II heterostructure with low resistance tunneling barrier. The source region is situated in a vertical position, enclosed by two sidewall channels that encompass a broad area of tunneling. Our proposed design effectively blocks the electric field that is originated from the drain at the tunneling junction, thereby conferring high immunity to drain induced barrier thinning effect. The device that has been suggested offers a significantly greater on-state current, a factor of 144, when compared to the traditional TFET and provides a subthreshold swing of 3mV/dec and an on/off current ratio of 9. 76×1010. According to statistical analysis, the design parameters of metal gate workfunction value and source doping concentration are crucial and have the potential to impact device performance. Therefore, selecting the appropriate combination of these parameters is essential. The proposed device serves as a foundation for the development of computing systems that are low in power and high in speed.

This study explores the use of distortion product otoacoustic emission (DPOAE) as a hearing screening modality for newborns and adults with hearing impairment. The goal is to improve cochlear response by developing digital filter characteristics to make it consistent for specialists to make accurate diagnoses. To accomplish this, the proposed system consists of a DPOAE ER-10C as stimulation and cochlear response probe, a digital signal processor, an oscilloscope, PC, and audio cables. Real-time distortion product frequency components were extracted using a signal processor of TMS320C6713. To validate the system, a senior medical physicist at Baghdad Medical City in Iraq conducted a study with five hearing-normal volunteers ages 38 and 55 at the center for hearing and communication. The results showed an ability to extract distortion product components in real-time implementation, with the superiority of shape parameters greater than 0.5. In addition, the quantization of filter coefficients was compared for both floating-point arithmetic and fixed-point arithmetic. Noisy environment-based noise reduction techniques have to be investigated by considering the implementation of robust digital signal processing techniques. Finally, the proposed system would contribute to advancements in hearing screening and treatment for those with hearing impairment.

Cardiovascular diseases (CVD) are today a major cause of death globally that is diagnosed by measurement and quantification of left ventricle (LV) wall motion (WM) abnormality of the heart. The aim of this study was to assess the utility of left ventricular (LV) entropy, a novel measure of disease derived from two-dimensional (2D) echocardiography images that assesses the probability distribution of pixel intensities in the LV. The purpose of this research is to develop the method of LV entropy to predict heart diseases. In this algorithm, a frame is usually chosen as the reference frame to extract the region of interest (ROI) around LV and then it is mapped to all images in a cardiac cycle. Then Shannon Entropy transform was applied to calculate the distribution of pixel intensities across the LV so we obtained entropy curves and compared them. The main idea is to find a motion estimation accuracy. The results obtained by our method are quantitatively evaluated to those obtained by an experienced echocardiographer visually on 22 normal cases and 19 myocardial infarction (MI) cases in apical four-chamber (A4C) view. The entropy of diastole in MI cases was 0.50 (0.29-0.58) while in normal cases was 0.75 (0.64-1.13). The entropy of systole in MI cases was 0.64 (0.26-1.04) while in normal cases was 0.81 (0.63-1.26). The percent change of entropy for diastole and systole between normal and MI cases are 33.3% and 20.2%. The results indicate that the LV entropy curves of MI cases have less changes than normal cases.

The proposed research presents a two-port compact Multiple Input Multiple Output (MIMO) antenna for Ultra-Wide Band (UWB) applications. The designed antenna has two identical radiators and has an overall dimension of 20 × 44. 1 × 1. 6mm3 on a FR4 substrate. The designed antenna is fed by a 50-microstrip line. Extended F-shaped stubs are introduced in the shared ground plane of the proposed antenna to produce high isolation between the MIMO antenna elements. Extended F-shaped stubs are introduced in the ground plane to produce multiple resonance and high isolation between the radiating elements. The antenna offers good impedance matching in the UWB band. The proposed antenna has lower isolation <-25 dB and Envelope Correlation Coefficient (ECC) < 0. 015 from 3. 1 to 10. 6 GHz. Antenna parameters are evaluated in term of return loss, ECC, Diversity Gain (DG), gain, Total active reflection coefficient (TRAC) radiation pattern and isolation. The proposed antenna is tested and fabricated. However, obtained results are good agreement which make suitable for UWB wearable applications.

Nonvolatile computing have been shown to be effective in the face of the sudden power outage for wireless sensor networks, Internet-of-Things applications, data converters, and emerging energy-harvesting circuits. It also plays a significant role in power-gating to minimize the leakage power for improving the energy efficiency. However, using on-chip backup module for D flip–flop has a bottleneck, and result in an increase in total power consumption, occupied area, and reduced calculation speed. Furthermore, the backup module needs external control signals, which increases the complexity of the circuit. This paper proposes a novel nonvolatile flip-flop with simultaneous data backup capability, which uses NCFET ferroelectric transistor to fundamentally advance the non-volatile computing paradigm. Proposed NVFF exhibits 0.8% faster and 5.0% smaller energy than previous works, while uniquely providing Radiation-Hardened feature.

The Recent development of 2-DOF electrical machines leads to increasing need for 2-DOF position sensors. Using a planar sensor instead of two linear ones decreases the complexity, and cost of the employed drive. Therefore, in this paper a new slotless configuration is proposed for the planar resolver, that simplifies the manufacturing of the sensor. Then, the optimal combination of the stator/mover number of coils is determined based on the proposed analytical model. Finally, to reduce the number of integrated parts of the proposed resolver, a new configuration with skewed coils is proposed. The success of the developed model and the presented configuration is validated using three-dimensional finite element analysis.

Directed Acyclic Graphs stand as one of the prevailing approaches for representing causal relationships within a set of variables. With observational or interventional data, certain undirected edges within a causal DAG can be oriented. Performing intervention can be done in two different settings, passive and active. Here, we prove that an optimal intervention set can be obtained based on the minimum vertex cover of a graph. We propose an algorithm that efficiently identifies such an optimal intervention set for chordal graphs within polynomial time. Performing intervention on this optimal set recovers all the undirected edges in graph G, regardless of the underlying ground truth DAG. Furthermore, we present an algorithm for evaluating the performance of passive algorithms. This evaluation provides insights into how many intervention steps of a specific algorithm are required to recover all edges in the causal graph for any possible underlying ground truth in the equivalence class. Experimental findings underscore that the number of nodes in the optimal intervention set increases with growing the number of nodes in a graph, where the edge density is fixed, and also increases with the rising edge density in a graph with a fixed number of nodes.

Cardiovascular arrhythmia is indeed one of the most prevalent cardiac issues globally. In this paper, the primary objective was to develop and evaluate an automated classification system. This system utilizes a comprehensive database of electro-cardiogram (ECG) data, with a particular focus on improving the detection of minority arrhythmia classes. In this study, the focus was on investigating the performance of three different supervised machine learning models in the context of arrhythmia detection. These models included Support Vector Machine (SVM), Logistic Regression (LR) and Random Forest (RF). An analysis was conducted using real inter-patient electrocardiogram (ECG) records, which is a more realistic scenario in a clinical environment where ECG data comes from various patients. The study evaluated the models’ performances based on four important metrics: accuracy, precision, recall, and f1-score. After thorough experimentation, the results highlighted that the Random Forest (RF) classifier outperformed the other methods in all of the metrics used in the experiments. This classifier achieved an impressive accuracy of 0. 94, indicating its effectiveness in accurately detecting arrhythmia in diverse ECG signals collected from different patients.

This paper introduces a floating flux-controlled meminductor emulator, implemented using two voltage differencing differential difference amplifier (VDDDA) along with a memristor and capacitor. Grounded and floating configurations are simulated with TSMC 0.18 µm level-49 BSIM3 CMOS process parameters in LTspice, showcasing the performance of the proposed circuits. The circuit features electronic tunability, allowing for the adjustment of nonlinear flux through the tuning of bias voltage. Simulation results validate the frequency-dependent current-flux dynamics of the proposed meminductor emulator. The simulation results, which involve frequency-dependent pinched hysteresis loops, transient analysis, non-volatility, and Monte Carlo analysis of the proposed meminductor, affirm the functionality and adequacy of the proposed design. A Chua’s oscillator is realized using proposed VDDDA-based meminductor as non-linear element.

The overall performance of any integrated circuit is defined by its proper memory design, as it is a mandatory and major block which requires more area and power. The prime interest of this article is to design a memory structure which is tolerant to variations in CNFET (Carbon nanotube field effect transistor) parameters like pitch, diameter and number of CNT tubes, and also offer low power and high speed of operation. In this context, CNFET based stacked SRAM (Static random access memory) design is proposed to attain the above mentioned criteria. Concept of stack effect is utilized in the cross coupled inverter section of the memory structure to attain low power. The power, speed and energy analysis for the proposed structure is done, and compared with the conventional structures to justify the proposed memory cell performance. HSPICE simulation results has confirmed that the proposed structure offers about 34%, 54% and 95% power saving in hold mode, read mode and write mode respectively. In speed and energy point of view it provides about 97% read delay, 92% write delay and 98% energy savings than the conventional memory structures. These results make it clear that the proposed SRAM is suitable for the 5G networks where circuit speed, power and energy consumption are the major concern.

A novel architecture is proposed in the present paper for detection and monitoring of air pollution at real-time condition following industrial standard, embedded with gas sensors which are able to identify both organic as well as inorganic hazardous contents. A vis-à-vis comparative analysis is carried out with existing literature highlighting cons of most referred circuits, both in component, system and power consumption levels, and a generalized drawback is reported citing their inefficacy for real-time data collection and accuracy level. Detailed review is reported based on qualitative assessments also, and henceforth, justifies the significance of the proposed design; where not only higher ranges of detection are possible, however is also associated with lower power consumption (26.41% and 10.71% respectively compared to the two latest circuits) and finer detection of dust particles even at extremely low concentration. The architecture will help to implicate precautionary steps at real-time condition for controlling the harmful effect in Society.

This paper investigates the dynamics of mmWave at the free space-human skin interface. The four Fresnel equations tailored for parallel and perpendicular polarizations, are employed in the analysis. The research reveals that for human tissue with relative permittivities (18.99, 15.51, 13.35, 11.69, 10.40) and conductivities (22.48, 27.09, 29.76, 31.79, 33.38) S/m, when exposed to 5G mmWave frequencies (24, 30, 35, 40, 45) GHz, respectively, exhibits Brewster angles of (79º, 78º, 77º, 76º, 75º), respectively. Additionally, it is shown that Brewster angles exist between 60º and 80º which aligns with existing literature using Gabriel’s skin model. To further validate obtained results, use is made of the results of the Gabriel’s skin model at (40, 60, 80, 100) GHz with the respective permittivities and conductivities, to generate new power reflection coefficients for the parallel and perpendicular polarizations for the sake of comparative analysis. First, comparisons of the curves for the Gabriel’s skin model reported in the literature with this work, show fairly good agreements. Second, the Brewster angles of (78º, 76º, 74º, 73º) obtained from this work, for the respective frequencies compare favorably with (75º, 74º, 70º, 69º) extracted from Gabriel’s skin model curves reported in the literature, with all values falling within the expected range of 60º to 80º.