Miracle-dz/UniFAR-FTUs huggingface dataset:
Mean-Squared Error Beamforming for Coherent Plane-Wave Compounding

The goal of this paper is to implement a new minimum mean-squared error (MMSE) beamformer for coherent plane-wave compounding. In ultrasound imaging, an beamformer, in the MMSE approach, is usually derived as a multiplication of the minimum variance distortionless response (MVDR) output and a scalar, which is approximated by the coherent factor (CF). Beside the spatial smoothing adopted for estimating the data covariance matrix in MVDR beamforming, this approximation could be another factor that potentially reduces performance of the MMSE. In this paper, we extend the spatial coherent approach that we developed previously for MVDR beamforming, and show how this scalar can be estimated through an array of MVDR outputs. Advances of the proposed MMSE are evaluated on datasets available on PICMUS website. The imaging results show it offers improvements, in terms of spatial and contrast resolution, over the corresponding MVDR and a combination of MVDR beamforming and CF in the literature.
Phase Dithered Modulation in Switched Mode Excitation for Improved Amplitude Control

Multi-level switched mode transmitters provide a simplified method of exciting ultrasound transducers compared to linear amplifiers. Excitation waveforms are created which switch between typically 3 or 5 high voltage supplies with high drive current. Previously, Harmonic Reduction Pulse Width Modulation (HRPWM) has shown how control of amplitude and instantaneous frequency or phase can be achieved. Arbitrary excitation can be achieved using Arbitrary Harmonic Reduction Pulse Width Modulation (AHRPWM). However, the synthesis of exact tones frequencies remains problematic, especially where high frequencies, low amplitudes, or integer divisions of the transmitter sampling frequency occur. This paper presents a method of improving the amplitude control of modulated waveforms through the application of phase dithering. The addition of random noise to phase during the calculation of the modulated waveforms has the benefit of disturbing periodicity which occurs where the synthesized frequency is an integer division of the sampling frequency. An experimental investigation demonstrates the improvement of amplitude control from 11% to 3% standard deviation for a 10 MHz switched waveform sampled at 80 MHz.
The Performance of Coded Modulation with Gallager Mapping in the Finite Length Regime

This paper investigates the capacity of coded modulation (CM) schemes with Gallager mapping based constellations in the finite length regime. We first present the channel capacity for M-ary modulations with a finite block-length. Then, we discuss the performance of Gallager mapping based constellation with probabilistic shaping. We show that at an asymptotic high signal-to-noise-ratio (SNR), the channel capacity of equiprobable constellations with a finite block-length can reach the capacity with infinite block-length while the channel capacity of nonequiprobable constellations can not approach the capacity in the infinite length regime. Finally, we discuss the channel capacity loss of non-equiprobable constellations in the finite length regime. At an asymptotic high SNR, the channel dispersion of nonequiprobable constellations equals to a positive constant, which causes the channel capacity loss for non-equiprobable constellations. We also derive an upper bound and a tight approximation of the asymptotic capacity loss (ACL) of the constellations in the finite length regime.
Impact of Solar Power and Load Demand Forecast Uncertainty on the Optimal Operation of Microgrid

Operation optimization of a microgrid is formulated based on the forecast of renewable energy resources and electricity demand. The forecast error will introduce uncertainties thereby affecting the accuracy and optimality of the solution. In this paper, the impact of this uncertainty is investigated as it receives little attention in the literature. First, an accurate forecasting model for solar irradiance and electricity demand using long short-term memory recurrent neural network and feedforward neural network is developed. To improve the forecasting accuracy, the k-means clustering algorithm is used to partition the datasets into a number of clusters. Second, MDSTool is used to simulate a one-year operation optimization of the microgrid using both the actual and forecasted data. MDSTool is a decision support tool that we developed in our previous work. We find that the forecast errors have a significant impact on the microgrid’s annual energy savings.
Resource Allocation for Energy Efficiency in NOMA Enhanced Small Cell Networks

In this paper, we consider a downlink non-orthogonal multiple access (NOMA) heterogeneous small cell networks (HSCN), where the macro base station (MBS) simultaneously communicate with multiple small cell base stations (SBS) through the wireless backhauls. The goal is to investigate an energy-efficient power, and bandwidth allocation scheme aiming at maximizing the EE of the small cells in downlink NOMA-HSCN constrained by the maximum transmit power and the minimum required data rate simultaneously. The optimization problem is non-convex due to the fractional objective function and non-convex constraints and is challenging to obtain an exact solution efficiently. To deal with the problem, the joint optimization is first decomposed into two subproblems. Then, an iterative algorithm to solve the power optimization subproblem is proposed with guaranteed convergence. Furthermore, a closed-form solution for the bandwidth allocation subproblem is derived. Finally, an iterative power and bandwidth allocation algorithm are proposed for NOMA-HSCN. Simulation results reveal the effectiveness of the proposed schemes in terms of energy efficiency (EE) as compared to the existing NOMA schemes and the conventional orthogonal multiple access (OMA) baseline schemes.
Driving Circuit Design for Electrostatic Ultrasonic Transmitter

In this paper, we report a driver circuit design for electrostatic-type of airborne ultrasound transmitter. The proposed circuit consists of a CMOS switch and an inductor to drive the capacitive load. In the experiment, the prototype system including the transducer achieved 37 % electro-acoustic energy conversion efficiency. Besides, we prototyped a phased array with the proposed circuit and evaluated the focusing performance.
RESOURCE ALLOCATION FOR MULTIUSER VIDEO STREAMING IN UAV RELAY NETWORKS

We all have encountered unsatisfactory video viewing experience with mobile devices in hot spot areas where a crowd of people are demanding video streaming simultaneously. One possible solution to relieve the problem is to use the unmanned aerial vehicle (UAV) as a relay to improve the quality-of-experience (QoE). In this paper, we focus on the allocation of bandwidth and transmission power for multiuser video streaming in UAV relay networks. Our goal is to maximize the total long-term QoE of users, which are determined by the freezing time and the bit rate of video. We employ the Lyapunov optimization theory to transform the original problem with long-term average form into the drift-plus-penalty problem. Considering the energy constraint of UAV, we propose a decentralized allocation scheme using alternative ascending clock auction to derive the optimal solution. Simulations are conducted to demonstrate the the superiority of the proposed method.
Harmonic Model and Propagation in Power System: A Review

Recent rapid interest in renewable energy generation, especially high penetration of grid-connected renewable energy system, is imposing new challenges to the harmonic model and propagation in power system. In practice, there is a potential risk of harmonic interaction resonance and harmonic propagation. It is of great importance to identify which kind of harmonic model and harmonic propagation are for further harmonic analysis. This review will help reader to understand the following important questions: How to model the harmonics generation from power converters? How to model the transportation of harmonics in power system? How the harmonic affect the power quality. It will provide a useful reference to researchers and engineers who concern about harmonic problems resulted from the grid-connected renewable energy systems.
Minimum Variance beamforming for closely spaced microbubbles

The Minimum Variance beamformer (MVB) is known to outperform the conventional Delay-and-Sum (DAS) beamformer in terms of lateral resolution. Super-resolution ultrasound imaging (SRI) relies on localising several microbubbles in each image, and thus the objective of this work is to assess how the distance between two scatterers can affect their apparent size or shape on the image by using the MVB. The MVB method was employed on simulated point scatter data with a 8 MHz (λ=192 μm) 128-element linear array probe. Two scatterers were placed in variable positions in three dimensions and closely spaced to each other. The lateral Full-Width-Half-Maximum (FWHM) was used for performance evaluation. It was found that the FWHM of each scatterer was affected by the presence of another, and decreased as the distance between two scatterers increased. Relative positioning in axial (0.1mm apart) or azimuthal (1 mm apart) positions provided a tilted scatterer appearance. As the MVB differentiates scatterers at closer distances compared to the DAS beamformer, it is concluded that a larger number of microbubbles can be counted using the former.
The Impact of Analog Front-end Filters on Ultrasound Harmonic Imaging

Ultrasound (US) harmonic imaging has shown advantages in better spatial resolution and contrast compared to classic fundamental imaging, but it suffers from more attenuation due to the increased frequency. To achieve more penetration, high dynamic range (DR) front-end electronics is required to receive the weak harmonic components. Typical US front-ends use a variable gain amplifier (VGA) to compensate part of the required DR, in order to avoid using a highly sensitive analog-to-digital converter (ADC). However, in harmonic imaging, the received signal amplitude is dominated by the fundamental component, thus the VGA is less efficient for these small harmonics. An analog front-end filter can be used before the VGA to mitigate this issue but this has an impact on spatial resolution by changing the dominant frequency component and spatial pulse length of the received signal. In this work, a combined acoustic-and-electronic model is made to understand the impact of the use of an analog front-end filter in US harmonic imaging applications in terms of imaging resolution, contrast, and hardware requirements.
Comparison of PI and PR Controllers with Adaptive Notch Filter for LCL Filtered Grid-Tie Converters under Weak Grid

Renewable energy sources such as solar and wind require power converters and harmonic filters for interconnection with the grid. Central to the operation of such systems is the controller, which ensures that the maximum possible power is transferred from the source to the grid. Of these controllers, the proportional-integral (PI) controller is the most commonly used, owing to its ease of implementation. This report therefore aims at comparing the operation of the PI controller with its stationary reference frame equivalent known as the proportional-resonant (PR) controller. Both controllers are implemented in the voltage oriented control scheme for a three phase converter connected to a weak grid through an LCL filter. The characteristics of the controllers are analysed and compared in both the time and frequency domains. Simulation results validate the performance of each controller.
Investigation of Flux Weakening Capability of an Unconventional 9-Phase PM Motor with Different Winding Configurations

In this paper, two different winding configurations and phase angle displacements of an unconventional nine-phase permanent magnet (PM) motor have been investigated in terms of flux weakening capabilities. The focus has been on a 117-slot 36-pole unbalanced and asymmetric winding motor since these motors have certain benefits. In addition, it is not possible to create a balanced winding structure for this motor due to the selected slot-pole combination. Performance of the designed motors have been verified experimentally and flux weakening capabilities have been investigated using 2 Dimensional finite element analysis (2D FEA) and test results. It is shown that the flux weakening capabilities of the proposed 9-phase PM motors with two winding options yield similar results compared to a conventional balanced multi-phase PM motors.
Cellular-Level Structure Imaging with Micro-optical Coherence Tomography $\mathbf{(\mu OCT)}$ for Kidney Disease Diagnosis

Chronic kidney disease (CKD) is one of the public health threats around the world, which may cause serious health problems like cardiovascular disease, kidney failure, or even more serious as premature death. Although CKD usually could be managed by general internists, such a way of treatment can be applied only when significant symptoms appear, which is very slow. It has also been reported that CKD could be characterized by means of glomeruli, and classified by the stages of disease severity for early treatment. However, due to lack of reliable method to detect the cellular-level microstructures for disease severity characterization, the diagnosis is troublesome, and thus, the treatments might be delayed while the best treatment time could be missed. For early detection of CKD, it is imperative to develop reliable tools to detect and characterize the disease at an early stage with minimal or noninvasiveness. For this research, the micro-optical coherence tomography $\mathbf{(\mu OCT)}$ was assessment it feasibility as a cellular-level structure imaging tool in kidney disease diagnosis at an early stage. Specifically, by measuring the number of glomeruli within a volumetric kidney tissue, a new diagnostic criteria is also established. Imaging results of the kidney specimens as compared their corresponding histology show that the cellular-level glomeruli structures could be identified clearly, and as a basic functional unit of kidney, it could be utilized as a reliable parameter to access the severity of the CKD.
Negative Resistance Feedback Oscillator Design for Internet Over TV (IOTV) Application

The aim of this research is to design a down frequency converter to shift WiFi frequency (2.45 GHz) into 720 MHz which is suitable for transmission of internet data over TV band white spaces. In this paper a 1.73 GHz negative resistance oscillator has been designed and simulated. This oscillator is used as a part of down frequency converter.
A 13-Level Hybrid Multilevel Inverter Topology by Combining ANPC and Improved H-Bridge

The research on multilevel inverter has created a milestone due to its wide application areas starting from industries to smart grid systems. Due to the increase of power demands, the importance of inverters increases in the microgrids and standalone systems. This paper presents a single phase hybrid cascaded structure of active neutral point clamped converter with modified H-bridge multilevel inverter. The five level active neutral point clamped converter is cascaded with nine level modified H-bridge to generate 13 level output voltage. This combinational structure reduces some source count by maintaining higher voltage levels. The mathematical analysis is provided with the simulation and experimental results for validation of the topology. The symmetrical source configuration is implemented for the voltage level generation. The series combination of resistive - inductive is considered in the load side. This structure is well suited for the PV applications where the inverter structure can be cascaded for increased power level.
Robust H∞ Filtering for Networked Control Systems with Random Delays and Packet Dropout via Delta Operator

This paper is concerned with the problem of H∞ filtering for uncertain delta operator systems with random delays and packet dropout. The discussed networked control systems are modeled as parameter uncertain systems with stochastic packet dropout, and the random delays are described by a Markov stochastic process. Sufficient conditions for the asymptotical stability of filtering error systems with H∞ performance are proposed by Lyapunov functional approach in delta domain. The parameterization expression of the designed filter is obtained in terms of linear matrix inequalities. A numerical example shows the effectiveness of the presented method.
Zero-Current Switching Impedance-Source DC-DC Converter

This paper presents a novel soft-switching technique for the galvanically isolated impedance-source full-bridge DC-DC converters. It allows reducing the turn off losses of the inverter switches, which otherwise represent a significant portion of the total power loss in such converters. Zero-current switching is achieved by the introduction of the additional energy return interval provided by the secondary side switches in addition to conventional synchronous rectification. This operation allows to redistribute the transformer current from one pair of switches to another, thus decreasing the current in the switch pair to be turned off. The paper presents the generalized operation principle corroborated with the simulation and experimental verification of the proposed modulation method.
Adaptive Control Method to Manage SOC for Energy Storage in DC Electric Railways

Incorporating energy storage systems (ESSs) into electric railways has been shown to be advantageous for energy saving and power quality enhancement. For DC railways, the connection method of the ESS to the track may impose restrictions on charging and discharging the ESS to control the state of charge (SOC). Without management of the SOC, the ESS is shown in this study to reach minimum or maximum limits, reducing its effectiveness due to unavailability. Whilst it is possible to oversize the capacity of ESS, this incurs increased costs and requires more physical space. The main objective of this study is to propose and validate a control algorithm that prevents the ESS from reaching the maximum or minimum SOC limits whilst maintaining the benefits of the system. The main concept of the proposed control method is to dynamically update the voltage and current setpoints of the ESS to manage its SOC. The control algorithm is implemented in the MATLAB software and the simulation results are validated against experimental results, using a track emulator and supercapacitor. The findings demonstrate that, with appropriate dynamic charge/discharge control, the SOC levels can be adequately managed and no external load or source is required.
Gear Collision Reduction of Geared In-Wheel-Motor by Effective Use of Load-Side Encoder

Requirement of large motor torque with limited mounting space for In-wheel-motors (IWMs) expects a geared drivetrain, but the vibration and noise caused by gear collision deteriorates ride comfort. In our previous study, our research group proposed to apply joint torque control using motor-side encoders and additional load-side encoders to geared IWMs and the effectiveness is validated. However, in point of space and costs, the effect of mounting load-side encoders should be investigated carefully. In this paper, joint torque control using both motor-side and load-side encoders is compared with joint torque control using only motor-side encoders. Simulations and experiments demonstrate that load-side encoders make it possible to design controller without vehicle parameters and to reduce the impact of collision sufficiently.
Web-based Editor for Signal Interpretation Models

A web-based editor for Signal Interpretation Models (SIM) is presented in this paper. SIM is a modeling formalism specifically created to specify the occurrence of events based on signals variation. This formalism goal is not only to specify but also to support the validation and implementation of signals interpreters. These signals can be system input signals (environment signals) or system internal signals. The created web-based editor uses Asynchronous JavaScript and XML (AJAX) principles and runs at standard browsers. It supports the creation/edition of graphical SIM models, which are saved in XML files. The XML format and the well defined execution semantics of the SIM formalism, enable the integration of SIM with other tools. This means that the created models can be used as inputs in tools, such as automatic code generators, to create simulation or execution code (namely JavaScript, C, and VHDL). To illustrate the application of the developed editor, the model of a system that detects temperature sensor faults is presented. The created edition tool prototype is currently available at http://gres.uninova. pt/SIM-Tools/.
Stabilization characteristics of user load equipped with electric spring for various types of line impedance

In the last years, Renewable Energy Sources (RESs) have increasingly contributed to the power delivered by the grid. Despite the environmental benefits made by RESs, their unpredictable power production is responsible of variations in the voltage of the distribution lines that can be disruptive for the functioning of the supplied loads. Electric Spring (ES) is a device that faces such an issue by stabilizing the supply voltage of the critical load of a user in a simple but effective way. This paper is concerned with the stabilization characteristics of a user load supplied by a low-voltage distribution line and equipped with a reactive power-operated ES. After working out an ES model that facilitates the analysis of an ES-equipped user load, its stabilization characteristics are found for three types of line impedance, namely pure resistive, pure inductive and resistive-inductive. Comparison of the resultant characteristics shows the different performance of the ES-equipped user load under various types of line impedance.
A Review of Management Architectures and Balancing Strategies in Smart Batteries

Battery management systems (BMSs) play a critical role to ensure the safety and extend the lifetime of the Lithium-ion batteries. In the conventional BMSs, there are some disadvantages such as low scalability and insufficient flexibility. In order to enhance these performances and further increase their reliability, the smart batteries are proposed. The smart batteries are the cell-level BMSs, which are built by the integrated cell modules connected in series. Each integrated cell module can monitor its own states, control the bypass circuit, and can communicate with the master controller, thus they are also called smart cells. This paper presents the state-of-the-art of management architectures, communication implementations, bypass circuits, and bypass decision strategies in the smart batteries. Four different existing smart batteries are compared. According to the comparison, future trends of the smart batteries are provided.
A Novel Node-Level Rumor Propagation Model with Recommendation Mechanism

Nowadays, online social media have become an integral part of people daily life. To provide high-quality contents, a variety of recommender systems have been applied to social platforms. On the framework of epidemic theory, in this paper we present a novel node-level rumor propagation model that takes into account the influence of recommender systems. With the proposed model, we perform a series of numerical simulations to investigate the dynamics of rumor propagation. The result shows that with a recommendation mechanism rumors can fast spread through a social network. Also, we examine the effects of some factors in the proposed model. This paper provides theoretical insight into the influence of recommender systems on rumor propagation.