This work introduces a low phase-noise (PN) wideband voltage-controlled-oscillator (VCO) by proposing five ports transformer in 0.18-μm CMOS technology. The proposed VCO uses five ports transformer and operates in the low band when all the pMOS-nMOS cross-coupled VCO components are activated, whereas this VCO operates in the high band using only part of the transformer, and an nMOS cross-coupled core. The transformer is designed using the top metal layer (M6) and the first inductor is meander line U-shaped center tap inductor, while the second inductor consists of two shunted octagonal loops to increase the quality (Q-) factor compared with using a single-loop inductor. The wideband switched transformer VCO achieves a measured frequency tuning range (FTR) of 16.4-17.1 GHz with a PN of -113.3 dBc/Hz at 1-MHz offset, and from 17 to 17.9 GHz

Automatic detection and counting of vehicles in a video is a challenging task and has become a key application area of traffic monitoring and management. In this paper, an efficient real-time approach for the detection and counting of moving vehicles is presented based on YOLOv2 and features point motion analysis. The work is based on synchronous vehicle features detection and tracking to achieve accurate counting results. The proposed strategy works in two phases; the first one is vehicle detection and the second is the counting of moving vehicles. Different convolutional neural networks including pixel by pixel classification networks and regression networks are investigated to improve the detection and counting decisions. For initial object detection, we have utilized state-of-the-art faster deep learning object detection algorithm YOLOv2 before refining them using K-means clustering and KLT tracker. 

Voltage source multilevel inverters (MLI) is widely utilized in medium and high-power applications due to their advantages. Here, an 11-level, asymmetrical multilevel inverter topology is proposed. The topology utilizes four unidirectional switches, three bidirectional switches along with two dc sources. The proposed configuration of switches and the concept of the dc-link capacitor is utilized to generate eleven level output voltage. The reduced number of components such as power switches and DC sources, lower control complexity due to capacitors' self-balancing nature, and low total standing voltage (TSV) are the critical features of the proposed topology. Moreover, a reliability assessment of the topology shows that the topology has a high mean time to fault (MTTF), which makes it robust and reliable. Matlab/Simulink environment is used to develop a simulation model of the proposed topology, while PLECS is used for the thermal modelling and analysis of the converter. A prototype is developed and tested in the laboratory to validate the performance for different loading conditions. The proposed topology can be cascaded to produce the ‘n’ number of levels. The critical comparison of the proposed topology shows that the proposed circuit has advantages over other compared topologies.

This article presents the application of model predictive control (MPC) in high-performance drives. A wide variety of machines have been considered: Induction machines, synchronous machines, linear motors, switched reluctance motors, and multiphase machines. The control of these machines has been done by introducing minor and easy-to-understand modifications to the basic predictive control concept, showing the high flexibility and simplicity of the strategy. The second part of the article is dedicated to the performance comparison of MPC with classical control techniques such as field-oriented control and direct torque control. The comparison considers the dynamic behavior of the drive and steady-state performance metrics, such as inverter losses, current distortion in the motor, and acoustic noise. The main conclusion is that MPC is very competitive concerning classic control methods by reducing the inverter losses and the current distortion with comparable acoustic noise.

The application of model predictive control in electrical drives has been studied extensively in the past decade. This article presents what the authors consider the most relevant contributions published in the last years, mainly focusing on three relevant issues: weighting factor calculation when multiple objectives are utilized in the cost function, current/torque harmonic distortion optimization when the power converter switching frequency is reduced, and robustness improvement under parameters uncertainties. Therefore, this article aims to enable readers to have a more precise overview while facilitating their future research work in this exciting area.

This experimental study aims to explore the Lagrangian nature of fluid transport downstream of a bileaflet mechanical aortic valve under different malfunction scenarios that might be encountered clinically. Time-resolved planar particle image velocimetry measurements are performed to extract instantaneous velocity fields downstream of the bileaflet mechanical valve implanted in an elastic aortic model. The results show an increase in particle residence time with the severity of malfunction. This is attributed to the expansion of the recirculation regions downstream of the valve. The time-evolution of Lagrangian coherent structures over one cardiac cycle (using finite-time Lyapunov exponent fields) shows the effect of valve dysfunction on the material transport and its barriers inside the aorta. The unbalanced flow through the dysfunctional leaflets leads to a significant redistribution of the LCS, thus the fluid transport along the ascending aorta. Moreover, a new technique for the evaluation of the highest accumulated shear stresses is applied along the Lagrangian trajectory of particles being released from the extracted Lagrangian coherent structures where the highest stretching occurs. Finally, the induced non-laminar flow behavior by the valve dysfunction is analyzed using the time-frequency spectra of velocity signals at selected points in the ascending aorta.

Purpose—Mitral regurgitation (MR) is the second most common valve disease in industrialized countries. Despite its high prevalence, little is known about its impact on the flow dynamics in the left ventricle (LV). Because of the interdependence between valvular function and hemodynamics in the heart chambers, an exploration of the dynamics in the LV could lead to a diagnosis of MR. This in vitro study aimed to develop an advanced left heart simulator capable of reproducing several conditions of MR and to evaluate their impact on the LV flow dynamics in terms of flow structures and viscous energy dissipation (VED). Methods—A simulator, previously developed to test mechanical and biological valves, was upgraded with an original anatomically-shaped mitral valve made from a hydrogel. The valve can be used in healthy or pathological configurations. The nature and severity of the disease was controlled by applying specific strain to the chordae. In this study, in addition to a healthy condition, two different severities of MR were investigated: moderate MR and severe MR. Planar time-resolved particle image velocimetry measurements were performed in order to evaluate the velocity field in the LV and the VED induced by each condition. Results—Our results showed that MR led to flow disturbances in the LV that were characterized by an increase in mitral inflow velocity and by elevated values of VED. Interestingly VED increased in proportion to the severity of MR and with a dissipation predominating during systole. Conclusion—Considering these results, the introduction of new parameters based on LV VED could provide crucial information regarding the coupling between the mitral valve and the LV and allow for better stratification of patients with MR.

A high-power Y-junction circulator is proposed for radar applications in the Ku-band (12–18 GHz). The design consists of two identical circulators combined using power splitters at all ports. The overall circulator network achieves 20-dB isolation level and return loss over the Ku-band with a peak power level of 14 kW. An internally matched divider is used at one port of the overall system to eliminate the cavity resonances produced by the practical asymmetries between the two circulators. The asymmetry problem is analyzed in detail to understand the consequences of these practical variations fully. Experimental validation is done by a fabricated prototype and shows a good agreement between the simulated and the measured results with differences in the range of ±2 dB.

Despite the availability of in vivo, instantaneous, and three-dimensional intracardiac flow data, their clinical analysis from a Lagrangian perspective remains limited due to their high computational cost. As an example, identifying Lagrangian coherent structures (LCS) in cardiac flows is not routinely performed in clinical settings despite their ability to identify mixing and stagnation regions along with locations of elevated shear stresses. Here, we explore a recently developed approach, “Lagrangian descriptors”, which quantifies the finite time Euclidean arc-length of Lagrangian trajectories released from a grid of initial positions. Through the evaluated arc-lengths of a set of trajectories, signatures of the LCS (computed from the same initial condition) are captured. Notably, the Lagrangian descriptor approach extracts the LCS within the flow at least five times faster than the common geometrical approach (i.e., using finite-time Lyapunov exponents). In this work, we apply, for the first time, the Lagrangian descriptors approach to in vivo 4D-MRI velocity fields inside left ventricles. The results show the ability of this approach to rapidly reveal the LCS within the left ventricle and how their organization can be altered under healthy and pathological conditions.